Dissertations / Theses on the topic 'Transport delays'

Delays is a big factor when considering taking the public transportation or taking your own car. If delays were more predictable, more people would take the bus instead. This thesis results can be used to further develop more robust systems for predicting delays, thus, more people using the public transportation systems. This was done in collaboration with Hogia. Hogia is a company in Sweden that have their own solutions for calculating delays within public transportation. This thesis investigates if predictions using Machine Learning can improve Hogia’s predictions on bus delays. Python and various libraries are used for training and testing the Machine Learning model. The data available for this study was gathered and provided by Hogia. Raw data were analyzed and preprocessed to create and find features in it, and then used to train a Random Forest Regressor. The model’s predictions are analyzed with various measurements and then compared against their current solution, as well as the actual delays. The result of this study looks promising since only a small dataset of 30 days was used. Also, it gives an understanding of what features that can be of value when training a model. Even though the model’s predictions were in some cases far off compared to Hogia’s current solution due to outliers in the data, this study can be used for further research of utilizing Machine Learning for predicting delays.

The railway simulation software solutions available today are increasingly used for other purposes than they initially have been created for. These software products aimed at first to recreate the operations on a normal railroad network, with often a schedule allowing for minor delays. However, nowadays light rail as well as underground railway networks, which are highly congested and have high passenger exchange within the cities, are also simulated. Although these systems do have the same basic functionality as the full railway, there are effects that sometimes can’t be represented easily with the existing software solutions. One of these effects is the dynamic delay build up at the stations during peak-hour traffic: a vehicle that is already delayed will get more people at the next station, making the passenger exchange longer, and therefore accumulating delays. This often leads to the widely known effect of bunching, where several vehicles follow each other closely. This master thesis will show a method to implement the effect of dynamic dwell time delays on high frequency, high passenger frequentation systems in an existing microscopic railway simulation. The application of this effect is based on the analysis of the red lines of the Stockholm Tunnelbana system simulated with the OpenTrack software during a case study. There, the results show clearly that the effect of a dynamically growing delay can be achieved with the implemented method

The European Commission has foreseen a modal share of 30% by 2030 for rail freight transport. To achieve this increase in the modal share, enhanced reliability of rail freight services is required. Optimal functioning of shunting yards is one of the areas that can improve this reliability. Shunting yards are large areas allocated to reassemble freight trains for dispatching to new destinations. Their productivity has a direct impact on the overall performance of a rail freight network. Therefore, analysing and modelling of departure deviations from shunting yards are required to enhance the interactions between shunting yards and the network; this thesis contributes to this gap. Paper I investigates the probability and temporal distribution of departure deviations using a large data set comprising 250,000 departures over seven years from two main shunting yards (Malmö and Hallsberg) in Sweden. The probability distribution of departure deviations is found comparing four main distributions including the exponential, the log-normal, the gamma, and the Weibull according to the maximum likelihood estimates and the results of the Anderson-Darling goodness of fit test.  The log-normal and the gamma are shown the best fits for departure deviations: the former on delays, and the latter on early departures. In the temporal delay distribution, the weekly and monthly, but not yearly delayed departures are positively correlated with the network usage. However, for hourly delayed departures, a shunting yard involved with international traffic does not show any correlation between delayed departures and the network usage, whereas a domestic shunting yard shows a significant negative correlation between these two parameters.  The findings obtained from this thesis contribute to a better understanding of departure deviations from shunting yards, and can be applied in enhancing the operations and capacity utilization of shunting yards in future models. Papers II and III analyse the relationship between congestion in the arrival yard and departure delays using the same data set as paper I.  According to previous research, congestion plays an important role in shunting yard delays. With defining congestion as the number of arriving trains before departure time, paper II analyses this relationship limiting the arrivals and departures between the two shunting yards considering varying time periods before departure,whereas Paper III elaborates the analysis by defining congestion level in a fixed period of time before departure time including all arrivals and departures. Considering the data set used in the analysis, the results show that there is no significant relationship between the congestion in the arrival yard and departure delays of trains. It is possible that congestion may not impact the departure delays of trains, but it may impact the departure delays of wagons due to missed wagon connection or increasing wagon idle time, which can be explored with the availability of wagon connection data.  Additionally, future elaboration of congestion definition, covering congestion at the shunting yard level, may lead to further improved analyses.
Europeiska kommissionen har förutspått en markansandel på 30% framtill 2030 för järnvägstransporter av gods. För att uppnå denna ökning krävsökad tillförlitlighet hos järnvägstransporttjänster. Rangergodsbangårdars optimalafunktion är ett av de områden som kan förbättra denna tillförlitlighet.Rangergodsbangårdar stora områden som är avsedda för att koppla ihopgodståg för sändning till nya destinationer. Deras produktivitet har en direktinverkan på järnvägsnätets totala prestanda. Därför krävs analys och modelleringav avvikelser från dessa noder för att förbättra interaktionen mellanrangergodsbangårdar och järnvägsnätet. I papper I undersöks sannolikheten och den tidsmässiga fördelningen avavvikelser med hjälp av en stor datamängd som omfattar 250 000 avgångaröver sju år från två rangergodsbangårdar (Malmö och Hallsberg) i Sverige.Sannolikhetsdistributioner av avvikelser jämförs med fyra huvuddistributioner,exponentiell, log-normal, gamma och Weibull enligt de maximalasannolikhetsuppskattningarna och resultaten av Anderson-Darling godhetav passningstest. Log-normal och gamma visar sig passa bäst för avvikelser:den förstnämnda vid förseningar och den senare vid tidiga avgångar. I dentidsmässiga fördröjningsfördelningen är de veckovisa och månatliga men inteårliga försenade avgångarna positivt korrelerade med järnvägsnätets nyttjandegrad.För försenade avgångar per timme visar dock en rangergodsbangårdsom är inblandad i internationell trafik ingen korrelation mellan försenadeavgångar och järnvägsnätets nyttjandegrad, medan en inhemsk rangergodsbangårdvisaren signifikant negativ korrelation mellan dessa två parametrar.Resultaten från denna avhandling bidrar till en bättre förståelse av avvikelserfrån rangergodsbangårdar och kan användas för att förbättra drift och kapacitetsutnyttjandeav rangergodsbangårdar växelplatser i framtida modeller. Papper II och III analyserar förhållandet mellan trängsel i ankomstgårdenoch avgångsförseningar med hjälp av samma datamängd som i papperI. Enligt tidigare analyser spelar trängsel en viktig roll vid förseningar förrangergodsbangårdar. Trängsel definieras som antalet ankommande tåg föreavgångstid och papper II analyserar detta förhållande som begränsar ankomsteroch avgångar mellan de två rangergodsbangårdar med beaktande av olikatidsperioder före avgång, medan papper III utvecklar analysen genom attdefiniera trängselnivån under en fast tidsperiod före avgångstid inklusive allaankomster och avgångar. Med tanke på datamängden som användes i analysenvisar resultaten att det inte finns något signifikant samband mellan trängselni ankomstgården och tågens förseningar. Det är möjligt att trängsel kanskeinte påverkar tågens avgångsfördröjningar, men det kan påverka vagnarnasavgångsfördröjningar på grund av missad vagnanslutning eller öka vagnenstomgångstid, vilket kan undersökas med vid tillgång av vagnanslutningsdata.Dessutom kan framtida vidareutveckling av definitionen av trängsel som påen detaljerad nivå täcker rangergodsbangårdars alla delar, leda till ytterligareförbättrade analyser.

QC 20201105

Shift2Rail
FR8HUB

Dans le cadre de cette thèse, nous traitons le problème de flow-shop à deux machines avec temps de transport où l’objectif consiste à minimiser le temps de complétion maximal. Dans un premier temps, nous nous sommes intéressés à la modélisation de ce problème. Nous avons proposé plusieurs programmes linéaires en nombres entiers. En particulier, nous avons introduit une formulation linéaire basée sur une généralisation non triviale du modèle d’affectation pour le cas où les durées des opérations sur une même machine sont identiques. Dans un deuxième temps, nous avons élargi la portée de ces formulations mathématiques pour développer plusieurs bornes inférieures et un algorithme exact basé sur la méthode de coupe et branchement (Branch-and-Cut). En effet, un ensemble d’inégalités valides a été considéré afin d’améliorer la relaxation linéaire de ces programmes et d’accélérer leur convergence. Ces inégalités sont basées sur la proposition de nouvelles règles de dominance et l’identification de sous-instances faciles à résoudre. L’identification de ces sous-instances revient à déterminer les cliques maximales dans un graphe d’intervalles. En plus des inégalités valides, la méthode exacte proposée inclut la considération d’une méthode heuristique et d’une procédure visant à élaguer les nœuds. Enfin, nous avons proposé un algorithme par séparation et évaluation (Branch-and-Bound) pour lequel, nous avons introduit des règles de dominance et une méthode heuristique basée sur la recherche locale. Nos expérimentations montrent l’efficacité de nos approches qui dominent celles de la littérature. Ces expérimentations ont été conduites sur plusieurs classes d’instances qui incluent celles de la littérature, ainsi que des nouvelles classes d’instances où les algorithmes de la littérature se sont montrés peu efficaces
In this thesis, we study the two-machine flow-shop problem with time delays in order to minimize the makespan. First, we propose a set of Mixed Integer Programming (MIP) formulations for the problem. In particular, we introduce a new compact mathematical formulation for the case where operations are identical per machine. The proposed mathematical formulations are then used to develop lower bounds and a branch-and-cut method. A set of valid inequalities is proposed in order to improve the linear relaxation of the MIPs. These inequalities are based on proposing new dominance rules and computing optimal solutions of polynomial-time-solvable sub-instances. These sub-instances are extracted by computing all maximal cliques on a particular Interval graph. In addition to the valid inequalities, the branch-and-cut method includes the consideration of a heuristic method and a node pruning procedure. Finally, we propose a branch-and-bound method. For which, we introduce a local search-based heuristic and dominance rules. Experiments were conducted on a variety of classes of instances including both literature and new proposed ones. These experiments show the efficiency of our approaches that outperform the leading methods published in the research literature

This master’s thesis describes the development of a model of the catalystsystem aiming at control by an MPC. A well functioning model, which is suitable in control purpose, is important while emission legislation become more and more hard to fulfill for the car manufacturers. Much research has been done in the field of physical modeling of the system, but in this work a linear adaptive time discrete ARX-model is developed and validated.

The systems tendency to change its dynamic during usage implies that the model must be adaptive. The developed model proved to be well functioning and shows promising conditions for the MPC design. The system and the model are analyzed in the time- and frequency domains and the model is both implemented and validated in a Saab 9-5.

The work has been performed both at Saab Automobile Powertrain AB in Södertälje and in Vehicular Systems Dept. of Electrical Engineering at Linköpings University.

Linköpings kommun har i senaste trafikstrategin från 2010 antagit målet att år 2030 ska var femte resa i kommunen ske med kollektivtrafik. För att nå målet behöver kollektivtrafikens attraktionskraft öka. För att ta fram exempel på hur detta kan göras genomfördes examensarbetet med syftet att ”analysera hur korsningen mellan Brokindsleden och Söderleden i Linköping kan förändras för att minska fördröjningen för kollektivtrafik år 2030”. Analysen genomfördes med hjälp av mikrosimuleringsprogrammet PTV Vissim. I en simuleringsstudie jämfördes fyra olika scenarier. NU0 och NU1 som beskriver nuläget utan och med kollektivtrafiksprioritet. Jämförelsealternativet, JA, bygger på en trafikprognos för 2030 och i utredningsalternativet, UA, förändras JA för att minska kollektivtrafikens fördröjning. Den kollektivtrafiksprioritering som används idag beräknades i genomsnitt minska fördröjningen med fem procent per buss motsvarande tre sekunder. Denna minskning är dock inte signifikant. Om korsningen inte förändras till 2030 beräknades fördröjningen för kollektivtrafiken öka med 87 procent. Den övriga trafiken kommer att få en ökning med 45 procent. Utifrån dessa resultat gjordes flera förändringar i simuleringsmodellen, bland annat infördes prioritet för alla bussar och kollektivtrafikskörfält på Brokindsleden. Med förändringarna minskade fördröjningen för buss med 78 procent. Den övriga trafiken påverkas också positivt med en minskning på elva procent, nästan tio sekunder per fordon. Utifrån detta drogs slutsatsen att en förändring med de förslagna åtgärderna mycket väl kan vara alla trafikanter till nytta.

Hosts in the peer-to-peer networks need to communicate to each other directly, but majority of nodes in the Internet are private nodes, that is they are behind Network Address Translators(NAT), and cannot be reached directly like a public node. Therefore, NAT traversal techniques are required to enable nodes to make end-to-end connections. These techniques seems to be more effective over UDP transport compared to TCP. However, standard UDP lacks some useful features, such as reliability and in-order delivery of packets. It also does not have congestion control mechanism to prevent congestion in the links. In this protocol, named RABAT, we are going to present a transport library over UDP for peer-to-peer applications that provides a delay-based congestion control mechanism and also in-order delivery of packets. Our congestion control mechanism is derived from LEDBAT draft [8] and reliability implementation is based on standard TCP. RABAT provides both intra- and inter-protocol fairness, which in case of the latter is back-off to TCP. The protocol also enables users to change priority of the running transports at runtime. To the best of our knowledge, this is the first open-source implementation of LEDBAT in java.

University of Central Florida College of Engineering Thesis
Real-time, man-in-the-loop simulators are important tools for operator training as well as human performance research. Simulator implementation using digital computers offers many important advantages but may also cause problems. One of the most significant and troublesome artifacts of digital computer simulation is the presence of transport delays in the operator/vehicle control loop. Transport delays have been shown to destabilize the system, resulting in poorer control of the simulated vehicle. They may also contribute to an increased likelihood of simulator sickness in human operators. Therefore, it is desirable to be able to quantify simulator transport delays and to compensate the system in such a way that delay effects on operator performance and well-being are minimized. The research presented in this dissertation involved the measurement of simulator transport delay using two different methods: a time-domain approach involving the detection of a response to a simulated step control input, and a frequency-domain approach involving the measurement of phase shift from a simulated sinusoidal input. Algorithmic compensators (digital filters) were developed to provide phase lead to counteract the system transport delay. Two compensators designed using approaches previously described in the literature canceled out delay reasonably well; however, a new compensator design developed by the author provided more nearly ideal phase performance without introducing unwanted side effects such as visual jitter. The transport delay measurement and compensation techniques were applied to a low-cost, real-time interactive automobile driving simulator developed at the University of Central Florida. The investigations using both measurement techniques revealed that a substantial amount of delay was present in the system. The three delay compensators implemented in the simulator were found (by reapplication of the frequency-domain or steady-state delay measurement technique) to operate approximately as designed. Finally, a driver-in-the-loop experiment was conducted to assess the effect of delay compensation on driver/vehicle performance. While the small size of the experiment allowed no definite conclusions to be drawn regarding the efficacy of compensation, trends in the data were generally indicative of better performance with compensation.
Ph.D.
Doctorate;
Department of Electrical and Computer Engineering
Engineering
Electrical and Computer Engineering
178
xi, 178 leaves, bound : ill. ; 28 cm.

Mobile Ad hoc NETworks (MANETs) aim at making communication between mobile nodes feasible without any infrastructure support. Sparse MANETs fall into the class of Delay Tolerant Networks which are intermittently connected networks and where there is no contemporaneous end-to-end path at any given time. We first, propose a new reliable transport scheme for DTNs based on the use of ACKnowledgments and random linear coding. We model the evolution of the network under our scheme using a fluid-limit approach. We optimize our scheme to obtain mean file transfer times on certain optimal parameters obtained through differential evolution approach. Secondly, we propose and study a novel and enhanced ACK to improve reliable transport for DTNs covering both unicast and multicast flows. We make use of random linear coding at relays so that packets can reach the destination faster. We obtain reliability based on the use of so-called Global Selective ACKnowledgment. We obtain significant improvement through G-SACKs and coding at relays. Finally, we tackle the problem of estimating file-spread in DTNs with direct delivery and epidemic routing. We estimate and track the degree of spread of a message in the network. We provide analytical basis to our estimation framework alongwith insights validated with simulations. We observe that the deterministic fluid model can indeed be a good predictor with a large of nodes. Moreover, we use Kalman filter and Minimum- Mean-Squared-Error (MMSE) to track the spreading process and find that Kalman filter provides more accurate results as compared to MMSE

Les réseaux mobiles Ad hoc (MANETs) visent à permettent à des noeuds mobiles de communiquer sans aucun support d'infrastructure. Les MANETs dispersés entrent dans la catégorie des réseaux tolérants aux délais (DTN), qui sont des réseaux connectés par intermittence et où il n'y a aucun chemin de bout-en-bout persistant à n'importe quel temps donné. Nous proposons, d'abord, un nouveau protocole de transport fiable pour les DTNs basé sur l'utilisation d'accusés de réception ainsi que le codage linéaire aléatoire. Nous modélisons l'évolution du réseau conformément à notre plan en utilisant l'approche fluide. Nous obtenons le temps de transfert d'un fichier en fonction de certains paramètres optimaux obtenus par l'approche d'évolution différentielle. Deuxièmement, Nous proposons ainsi et étudions un nouveau mécanisme d'ACK augmenté, pour améliorer le transport fiable pour les DTNs, pour les cas unicast et multicast. Nous nous servons du codage linéaire aléatoire aux relais pour que les paquets puissent atteindre la destination plus rapidement. Nous obtenons la fiabilité basée sur l'utilisation Global Sélective ACKnowledgement. Enfin, nous abordons le problème de l'estimation de propagation des fichiers dans les DTNs avec livraison directe et le routage épidémique. Nous estimons et suivons le degré de propagation d'un message dans le réseau. Nous fournissons la base analytique à notre cadre d'évaluation avec des aperçus validés en se basant sur des simulations. En plus, nous utilisons le filtre de Kalman et Minimum- Mean-Squared Error (MMSE) pour suivre le processus de propagation et trouvons que le filtre de Kalman fournit des résultats plus précis par rapport à MMSE
Mobile Ad hoc NETworks (MANETs) aim at making communication between mobile nodes feasible without any infrastructure support. Sparse MANETs fall into the class of Delay Tolerant Networks which are intermittently connected networks and where there is no contemporaneous end-to-end path at any given time. We first, propose a new reliable transport scheme for DTNs based on the use of ACKnowledgments and random linear coding. We model the evolution of the network under our scheme using a fluid-limit approach. We optimize our scheme to obtain mean file transfer times on certain optimal parameters obtained through differential evolution approach. Secondly, we propose and study a novel and enhanced ACK to improve reliable transport for DTNs covering both unicast and multicast flows. We make use of random linear coding at relays so that packets can reach the destination faster. We obtain reliability based on the use of so-called Global Selective ACKnowledgment. We obtain significant improvement through G-SACKs and coding at relays. Finally, we tackle the problem of estimating file-spread in DTNs with direct delivery and epidemic routing. We estimate and track the degree of spread of a message in the network. We provide analytical basis to our estimation framework alongwith insights validated with simulations. We observe that the deterministic fluid model can indeed be a good predictor with a large of nodes. Moreover, we use Kalman filter and Minimum- Mean-Squared-Error (MMSE) to track the spreading process and find that Kalman filter provides more accurate results as compared to MMSE

Les réseaux mobiles Ad hoc (MANETs) visent à permettent à des noeuds mobiles de communiquer sans aucun support d'infrastructure. Les MANETs dispersés entrent dans la catégorie des réseaux tolérants aux délais (DTN), qui sont des réseaux connectés par intermittence et où il n'y a aucun chemin de bout-en-bout persistant à n'importe quel temps donné. Nous proposons, d'abord, un nouveau protocole de transport fiable pour les DTNs basé sur l'utilisation d'accusés de réception ainsi que le codage linéaire aléatoire. Nous modélisons l'évolution du réseau conformément à notre plan en utilisant l'approche fluide. Nous obtenons le temps de transfert d'un fichier en fonction de certains paramètres optimaux obtenus par l'approche d'évolution différentielle. Deuxièmement, Nous proposons ainsi et étudions un nouveau mécanisme d'ACK augmenté, pour améliorer le transport fiable pour les DTNs, pour les cas unicast et multicast. Nous nous servons du codage linéaire aléatoire aux relais pour que les paquets puissent atteindre la destination plus rapidement. Nous obtenons la fiabilité basée sur l'utilisation Global Sélective ACKnowledgement. Enfin, nous abordons le problème de l'estimation de propagation des fichiers dans les DTNs avec livraison directe et le routage épidémique. Nous estimons et suivons le degré de propagation d'un message dans le réseau. Nous fournissons la base analytique à notre cadre d'évaluation avec des aperçus validés en se basant sur des simulations. En plus, nous utilisons le filtre de Kalman et Minimum- Mean-Squared Error (MMSE) pour suivre le processus de propagation et trouvons que le filtre de Kalman fournit des résultats plus précis par rapport à MMSE
Mobile Ad hoc NETworks (MANETs) aim at making communication between mobile nodes feasible without any infrastructure support. Sparse MANETs fall into the class of Delay Tolerant Networks which are intermittently connected networks and where there is no contemporaneous end-to-end path at any given time. We first, propose a new reliable transport scheme for DTNs based on the use of ACKnowledgments and random linear coding. We model the evolution of the network under our scheme using a fluid-limit approach. We optimize our scheme to obtain mean file transfer times on certain optimal parameters obtained through differential evolution approach. Secondly, we propose and study a novel and enhanced ACK to improve reliable transport for DTNs covering both unicast and multicast flows. We make use of random linear coding at relays so that packets can reach the destination faster. We obtain reliability based on the use of so-called Global Selective ACKnowledgment. We obtain significant improvement through G-SACKs and coding at relays. Finally, we tackle the problem of estimating file-spread in DTNs with direct delivery and epidemic routing. We estimate and track the degree of spread of a message in the network. We provide analytical basis to our estimation framework alongwith insights validated with simulations. We observe that the deterministic fluid model can indeed be a good predictor with a large of nodes. Moreover, we use Kalman filter and Minimum- Mean-Squared-Error (MMSE) to track the spreading process and find that Kalman filter provides more accurate results as compared to MMSE

Cette thèse propose des algorithmes pour estimer la vitesse et la direction du vent pour des éoliennes et des parcs éoliens.Tout d'abord, nous proposons des méthodes basées sur les données pour estimer la vitesse effective du rotor (REWS) sans nécessiter la connaissance de certains paramètres physiques de l'éolienne, qui pourraient être inconnus de l'opérateur. Nous fournissons deux méthodes basées sur les données, l'une basée sur la régression par processus gaussien et l'autre combinant la régression par processus gaussien avec un observateur grand gain.Ensuite, en nous basant sur cette estimation locale de la REWS, au niveau d'une éolinenne, nous abordons la question de l'estimation du vent en écoulement libre au niveau du parc éolien.Nous commençons par nous concentrer sur l'estimation de la vitesse du vent, pour une direction du vent connue. Pour un parc éolien de géométrie simple, nous démontrons qu'une mesure locale de la vitesse perturbée par la présence des éoliennes peut être utilisée pour estimer la vitesse du vent en écoulement libre. Nous fondons notre méthodologie d'estimation sur une modélisation simplifiée de l'effet de sillage qui consiste en des équations aux dérivées partielles hyperboliques du premier ordre en cascade, et dont la vitesse de transport est la vitesse du vent en écoulement libre. Nous proposons d'utiliser une solution analytique de ces équations, impliquant des retards de transport, pour effectuer une estimation de la mesure locale et mettre à jour l'estimation de la vitesse du vent en écoulement libre. Nous démontrons formellement la convergence de cette estimation et illustrons numériquement l'efficacité de cette méthode.Enfin, nous passons à une configuration plus générale où à la fois la vitesse et la direction du vent en écoulement libre sont inconnues. Nous proposons d'utiliser une modélisation bidimensionelle du sillage et de nous appuyer sur une méthode basée sur l'optimisation. Le problème d'identification que nous formulons se révèle être particulièrement difficile en raison de l'apparition de retards de transport, mais nous montrons comment contourner cette difficulté en considérant une valeur moyenne de l'historique de la vitesse du vent en écoulement libre. Des résultats de simulation obtenus avec le simulateur FAST.Farm illustrent l'intérêt de la méthode proposée
This thesis designs algorithms to estimate the wind speed and direction for wind turbines and wind farms.First, we propose data-based methods to estimate the Rotor Effective Wind Speed (REWS) for a single turbine without prior knowledge of certain physical parameters of the turbine that might be unknown to an operator.We provide two data-based methods, based respectively on Gaussian Process Regression (GPR) and on an combination of GPR with high-gain observers.Second, grounding on this REWS estimation at the local level of one turbine, we address the question of estimating the free-flow wind at the level of a wind farm.We start by focusing on wind speed estimation, for a given known wind direction. For a wind farm with a simple geometry, we prove that a local speed measurement disturbed by the presence of the turbines can be used to estimate the free-flow wind speed. We ground our estimation methodology on a simplified wake model, which consists of first-order hyperbolic partial differential equations, the transport speed of which is the free-flow wind speed. We propose to use an analytical solution of these equations, involving transport delays, to perform an estimate of the local measurement and to update the free-flow wind speed estimate. We formally prove the convergence of this estimate and numerically illustrate the efficiency of this method.Finally, we move to a more general setup where both the free-flow wind speed and direction are unknown. We propose to use a two-dimensional wake model and to rely on an optimization-based method. This identification problem reveals to be particularly challenging due to the appearance of transport delays, but we illustrate how to circumvent this issue by considering an average value of the free flow wind speed history. Simulation results obtained with the simulator FAST.Farm illustrate the interest of the proposed method

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada
In many test ranges, it is often required to acquire a number of telemetry streams and to process the data simultaneously. Frequently, the streams have different delay characteristics, requiring temporal alignment before the processing step. It is desired to have the capability to align these streams so that the events in each stream are coincident in time. Terawave Communications has developed technology to perform temporal alignment for a number of streams automatically. Additionally, the algorithm performs the delay compensation independent of the source data rate of each stream. Terawave will present the algorithm and share the results of their testing in a test installation.

The media industry has during the last decade migrated services from dedicated medianetworks to more shared resources and lately also the public internet and public data centers. Inorder to cater for such transition, several protocols have been designed to meet the demand forhigh-quality media transport over lossy infrastructure, protocols such as SRT and RIST. Thepurpose of Reliable Internet Stream Transport (RIST) and Secure Reliable Transport (SRT) is tohave all vendors of broadcasting equipment support an interoperable way of communication. Thelack of interoperability locks consumers into one particular vendor’s family of products - most oftenthis equipment only supports a proprietary technology. Interoperability creates a more competitivemarket space which benefits consumers and gives vendors an incentive to be more innovative intheir solutions. The purpose of this thesis is to assess the performance of these protocols by comparing theirperformance to a proprietary solution (named ÖÖÖ in this thesis and seen as an establishedsolution in the industry). The challenge is to test these protocols in a lab environment, but have theresults represent real-world use. For this, a large subset of samples is needed along with samplesmeasured over a long period. This sampling was made possible by writing a script which automatesthe sampling process. The results indicate that the versions of RIST and SRT tested in this thesis to some extentcompare well to the selected established protocol (ÖÖÖ). In many scenarios, SRT even did muchbetter, mainly when a line with a single feed was tested. For instance, when the network suffered a2% drop rate and utilized retransmission SRT performed the best and was the only protocol whichhad some samples where no packets were dropped during one hour of measurements. Whenrunning all three protocols at the same time, SRT also did the best in a network with up to 12% droprate. The results in this thesis should give a broadcaster an idea of which of these protocols willfulfill their requirements in a broadcast application.
I mediabranschen finns det en efterfrågan på utrustning som har inslag av interoperabilitet.Anledningen till detta är att någon som köper produkter från en viss återförsäljare inte vill låsas in idenna återförsäljares ”ekosystem” i flera år framöver. Då en studio sällan uppgraderar hela sinproduktionskedja på samma gång ger interoperabilitet möjligheten att köpa utrustning från andraåterförsäljare när man ska uppgradera något i produktionslinan. Detta leder till en merkonkurrenskraftig marknad samt ger incentiv till nya innovativa lösningar. Detta examensarbete går ut på att utvärdera lösningar som tagits fram för att främjainteroperabilitet och jämföra dem med en existerande proprietärlösning. Reliable Internet StreamTransport (RIST) och Secure Reliable Transport (SRT) är två protokoll som tagits fram för just dettasyfte. Utmaningen med att utvärdera dessa protokoll är att i en labbmiljö få resultat som reflekteraranvändandet av protokollen i verkligheten. Detta har gjorts med hjälp av ett program som tagitsfram i detta examensarbete. Med detta program har testandet kunnat automatiseras. Resultaten i detta examensarbete visar potential hos båda RIST och SRT. SRT är i vissascenarion till och med bättre än den proprietära lösningen. Protokollen visar något buggigtbeteende i vissa instanser, såsom att i vissa fal sluta fungera och inte kunna återgå till normalfunktion utan manuell interaktion. Allt som allt är dock protokollen i de flesta fallen testade i dettaexamensarbete ett godtyckligt alternativ till den jämförda proprietära lösningen.

A Networked Control System (NCS) is a feedback-driven control system wherein the control loops are closed through a real-time network. Control and feedback signals in an NCS are exchanged among the system’s components in the form of information packets via the network. Nowadays, wireless technologies such as IEEE802.11 are being introduced to modern NCSs as they offer better scalability, larger bandwidth and lower costs. However, this type of network is not designed for NCSs because it introduces a large amount of dropped data, and unpredictable and long transmission latencies due to the characteristics of wireless channels, which are not acceptable for real-time control systems. Real-time control is a class of time-critical application which requires lossless data transmission, small and deterministic delays and jitter. For a real-time control system, network-introduced problems may degrade the system’s performance significantly or even cause system instability. It is therefore important to develop solutions to satisfy real-time requirements in terms of delays, jitter and data losses, and guarantee high levels of performance for time-critical communications in Wireless Networked Control Systems (WNCSs). To improve or even guarantee real-time performance in wireless control systems, this thesis presents several network layout strategies and a new transport layer protocol. Firstly, real-time performances in regard to data transmission delays and reliability of IEEE 802.11b-based UDP/IP NCSs are evaluated through simulations. After analysis of the simulation results, some network layout strategies are presented to achieve relatively small and deterministic network-introduced latencies and reduce data loss rates. These are effective in providing better network performance without performance degradation of other services. After the investigation into the layout strategies, the thesis presents a new transport protocol which is more effcient than UDP and TCP for guaranteeing reliable and time-critical communications in WNCSs. From the networking perspective, introducing appropriate communication schemes, modifying existing network protocols and devising new protocols, have been the most effective and popular ways to improve or even guarantee real-time performance to a certain extent. Most previously proposed schemes and protocols were designed for real-time multimedia communication and they are not suitable for real-time control systems. Therefore, devising a new network protocol that is able to satisfy real-time requirements in WNCSs is the main objective of this research project. The Conditional Retransmission Enabled Transport Protocol (CRETP) is a new network protocol presented in this thesis. Retransmitting unacknowledged data packets is effective in compensating for data losses. However, every data packet in realtime control systems has a deadline and data is assumed invalid or even harmful when its deadline expires. CRETP performs data retransmission only in the case that data is still valid, which guarantees data timeliness and saves memory and network resources. A trade-off between delivery reliability, transmission latency and network resources can be achieved by the conditional retransmission mechanism. Evaluation of protocol performance was conducted through extensive simulations. Comparative studies between CRETP, UDP and TCP were also performed. These results showed that CRETP significantly: 1). improved reliability of communication, 2). guaranteed validity of received data, 3). reduced transmission latency to an acceptable value, and 4). made delays relatively deterministic and predictable. Furthermore, CRETP achieved the best overall performance in comparative studies which makes it the most suitable transport protocol among the three for real-time communications in a WNCS.

This work presents a contribution to the study of control of dead-time systems. Within this context, it is presented a literature review covering from the Smith predictor until its recent variations. For the state space representation dead-time is normally dealt under the discrete-time perspective, where it is included as state augmentation. In the first case, this work proposes a novel control structure with simple tuning rules, able to deal with single input and output systems that presents multiple delays due to multiple internal paths. However, the design method allows the proposed structure to be readily applied for the single delay case. The study is extended for the state space representation, where it is presented a modification to a predictor recently presented in literature, in order to use it as a predictor-observer within the state space representation. In this case, all the matrices involved in the observer have the same order as those of the plant, i. e., there is no need of the state augmentation to deal with dead-time. Hence, the well known techniques for the optimal and robust control may be applied for multivariable delayed systems. Besides, an alternative way of tuning for the LQG control, based on the T-polynomial approach, is proposed. In this case, the technique may be applied for both the delay free systems and dead-time systems. The latter by applying the modified predictor mentioned earlier in the observer structure. Additionally, it is also proposed a new predictor structure, based on the CARIMA model with T-polynomial, for dead-time systems. This work is full of examples throughout the text which are suitable for both the control strategies studied herein and the proposed ones, applicable for stable, unstable or integrating systems, as well as multivariable systems. Case studies for laboratories plants validate the effectiveness of the discussed methods.
Este trabalho apresenta uma contribuiÃÃo ao estudo de controle de sistemas dinÃmicos que exibem atraso de transporte. Nesse contexto, apresenta-se uma revisÃo bibliogrÃfica que traz desde o surgimento do preditor de Smith atà algumas de suas variaÃÃes mais recentes. Na representaÃÃo baseada em espaÃo de estados à comum que se tenha a abordagem em tempo discreto, em que o atraso de transporte à normalmente incluÃdo atravÃs do aumento da ordem do estado. No primeiro caso, este trabalho traz a proposta de uma nova estrutura de controle, de sintonia simplificada, capaz de lidar com sistemas de entrada e saÃda Ãnicas, mas que apresentam mÃltiplos atrasos em caminhos diversificados internamente. A metodologia considerada, entretanto, permite que a estrutura proposta possa ser facilmente aplicada a sistemas com atraso simples. O estudo à ampliado para a representaÃÃo em espaÃo de estados no tempo discreto, em que apresenta-se uma abordagem que leva à adaptaÃÃo de um preditor proposto recentemente na literatura para atuar como observador de estados. Neste caso, tem-se a vantagem de que todas as matrizes envolvidas tem a mesma ordem daquelas que descrevem o sistema, ou seja, nÃo hà aumento da ordem do estado. Assim, as tÃcnicas conhecidas de controle robusto e Ãtimo para a representaÃÃo em espaÃo de estados podem ser aplicadas a sistemas com mÃltiplas entradas e saÃdas. Apresenta-se ainda uma forma alternativa de sintonia do controle LQG, baseada no polinÃmio-T. Neste caso, a sintonia proposta pode ser aplicada tanto para sistemas sem atraso de transporte quanto para aqueles com atraso quando se considera a adaptaÃÃo da estrutura do preditor no observador de estados. AlÃm disso, este trabalho apresenta ainda a proposta de um novo preditor cuja estrutura à baseada no modelo CARIMA com polinÃmio-T, aplicado a sistemas com atraso de transporte. O trabalho à repleto de exemplos em que aplicam-se tanto as estratÃgias de controle estudadas quanto as propostas, a sistemas estÃveis, instÃveis ou integradores em malha aberta, bem como a sistemas multivariÃveis. Estudos de caso aplicados a plantas de laboratÃrio comprovam a eficiÃncia dos mÃtodos discutidos.

Rapid and deep transport of solutes in soils can potentially pollute groundwater resources. Field estimates of solute leaching depth based on randomized sampling provide extremely variable field average estimates that confound the treatment effects of the leaching study with the high spatial variation of soil hydraulic properties. The purpose of this study was to investigate the spatial scale of variation of solute (Bromide) leaching depth, and apply this scale of variation to study the leaching depth of Bromide as a function of a sinusoidal application of transport causing factors, i.e., rainfall amount, intensity and application time delay. Solute leaching depth varied over different spatial scales. The deepest leaching was observed on plots where the Br center of mass ranged from 19-30 cm depth. Deep leaching occurred with large quantities of low intensity precipitations (5.5 to 6 cm/day) and short time delays (≤ 17 hours), respectively. The hydraulic gradient presented cyclic variation at 8 m wavelength across the 10-30cm depth compartment. Spectral analysis indicated that spatial variation of the leaching depth was mainly affected by precipitation amount and intensity and only a small portion of the leaching depth variation was caused by time delay. Cross-spectral analysis identified common cyclic variation between the Br leaching depth and precipitation amount, intensity and time delay over 32, 32 and 8 m wavelengths, respectively. Simulated Br concentration over depth and horizontal distance and soil water matric potential ψm were in good agreement with experimental observations, the latter revealing a satisfactory Br and water mass balance.

Deploying wireless networks in networked control systems (NCSs) has become more and more popular during the last few years. As a typical type of real-time control systems, an NCS is sensitive to long and nondeterministic time delay and packet losses. However, the nature of the wireless channel has the potential to degrade the performance of NCS networks in many aspects, particularly in time delay and packet losses. Transport layer protocols could play an important role in providing both reliable and fast transmission service to fulfill NCS’s real-time transmission requirements. Unfortunately, none of the existing transport protocols, including the Transport Control Protocol (TCP) and the User Datagram Protocol (UDP), was designed for real-time control applications. Moreover, periodic data and sporadic data are two types of real-time data traffic with different priorities in an NCS. Due to the lack of support for prioritized transmission service, the real-time performance for periodic and sporadic data in an NCS network is often degraded significantly, particularly under congested network conditions. To address these problems, a new transport layer protocol called Reliable Real-Time Transport Protocol (RRTTP) is proposed in this thesis. As a UDP-based protocol, RRTTP inherits UDP’s simplicity and fast transmission features. To improve the reliability, a retransmission and an acknowledgement mechanism are designed in RRTTP to compensate for packet losses. They are able to avoid unnecessary retransmission of the out-of-date packets in NCSs, and collisions are unlikely to happen, and small transmission delay can be achieved. Moreover, a prioritized transmission mechanism is also designed in RRTTP to improve the real-time performance of NCS networks under congested traffic conditions. Furthermore, the proposed RRTTP is implemented in the Network Simulator 2 for comprehensive simulations. The simulation results demonstrate that RRTTP outperforms TCP and UDP in terms of real-time transmissions in an NCS over wireless networks.

Le delta du Rhône (Méditerranée) connaît une dégradation de son littoral depuis plusieurs décennies. Un modèle numérique de de transport hydro-sédimentaire à haute résolution () a été appliqué à cette zone pour la première fois, afin de comprendre les processus à l'origine de la mauvaise redistribution des sédiments. Une attention particulière a été accordée aux événements de tempête et de crue, principaux moteurs morphologiques. Différents scénarios de houle et de débit ont été testés permettant de faire ressortir le rôle de l'aléa couplé sur l'équilibre morpho-sédimentaire qui contrôle la dynamique de la barre d’embouchure, les apports sédimentaires du fleuve vers les plages et le large et les processus de wave blocking et d’hydraulic groyne effect. Le transfert entre le lobe et les plages se fait par l’intermédiaire de zones de relais situées sur les flancs des levées subaquatiques. Enfin, le rôle de la morphologie sur les courants a été abordé en simulant des événements réellement observés sur une morphologie de 1955. Ces sorties montrent que la proximité de la barre d’embouchure à la côte, sa profondeur et l’absence de flèche sableuse à l’exutoire du fleuve favorisaient la libération de sédiments en mer. En même temps, les courants plus importants dans le chenal permettaient des apports sédimentaires plus importants et une meilleure alimentation des plages qu’aujourd’hui.Ce travail de thèse fait ressortir l’importance de l’organisation de l’aléa couplé (tempête et crue) sur le transport sédimentaire et potentiellement la morphologie de l’embouchure en jouant sur le rapport de force entre les dynamiques fluviales et marines
The coastline of the Rhône delta (Mediterranean Sea, south of France) is in degradation since several decades. A numerical high-resolution hydrosedimentary modelling (Delft3D) was applied for the first time to this area, in order to understand the processes that control the poor redistribution of sediments. A particular attention was paid to storm and flood events that are the main morphological forcings. Different wave and river flow conditions have been tested, showing the coupled hazard induces a morphosedimentary equilibrium which controls the dynamic of the mouth-bar, sediment inputs from a flood to the sea and the processes of wave blocking and hydraulic groyne effect. Sediment transfer to the beaches is controlled by waves but fed by the riverine sediment. The transfer between the lobe and the adjacent coastlines is discontinuous in time, with zone of temporary deposition (zone relais) located on the flanks of the underwater levees. Finally, the role of the morphology on currents was studied by simulating events effectively observed on a reconstructed bathymetric grid of 1955. These scenarios highlight that the shorter distance from mouth-bar to the coast, its depth and the absence of sandy mouth spit at the outlet favoured the transfer of riverine sediments to the open sea. At the same time, stronger currents in the channel permitted higher sedimentary inputs and improved the feeding of the beaches compared to nowadays.This work demonstrates the importance of the organization of coupled hazard (storm and flood) on sediment transport on a deltaic area and potentially the morphology of the mouth based on the equilibrium between river and marine dynamics

Com o desenvolvimento e disseminação dos protocolos de rede, o surgimento dos chips de ASIC e queda dos preços do silício (estes dois últimos fatores possibilitando com que os sensores e atuadores pudessem ser equipados com interfaces de rede e com isso se tornarem nós independentes em uma rede de controle em tempo real), viabilizaram o desenvolvimento dos sistemas de controle em rede que hoje em dia vêm sendo amplamente utilizados. Juntamente com o aparecimento dos sistemas de controle em rede, novos problemas surgiram sendo um deles o atraso de transporte nas comunicações dos sensores/atuadores/controladores e as conseqüências relacionadas a este fator. Este trabalho tem por objetivo contextualizar sistemas de controle em rede no que concerne novas metodologias de sistemas de controle, escalonamento e apresentar as influências causadas pela comunicação em redes Foundation Fieldbus no desempenho de sistemas de controle.
The development and dissemination of network protocols, the arising of ASIC chip and price drops in silicon (these two last factors allow sensors and actuators be equipped with network interfaces and thus become independent nodes in a real-time control network), make the development of Networked Control Systems possible, which became widely used. New issues - such as an increase in the communication delay among distributed sensors, controller, and actuators have to be handled by designers when developing networked control systems in order to ensure that stability and other usual control performance requirements are met. In this work, the timing behavior of a networked control developed using a Foundation Fieldbus-based network is studied and in particular the impact that communication parameters as jitter, macrocycle, and message scheduling have on control performance metrics like overshoot and settling time are evaluated both theoretically as well as experimentally.

Cette thèse se compose de trois articles autonomes, dont chacun correspond à un chapitre. Le premier chapitre, écrit conjointement avec Estelle Malavolti, étudie la conception optimale du contrat de réduction des retards signé entre un ANSP et une compagnie aérienne monopoliste. Dans la conception du contrat, nous considérons principalement le problème d’antisélection. En outre, nous effectuons une analyse comparatif-statique pour étudier les effets de la norme de sécurité et de la fréquence de vol sur les contrats optimaux. A la fin, nous utilisons des exemples numériques pour étudier le cas où un ANSP maximisant son bien-être doit utiliser des fonds publics pour fournir le service. Le deuxième chapitre étudie le double rôle des retards de congestion et de la différenciation horizontale des produits dans le choix du réseau aérien. Je trouve que, premièrement, en raison de l’inclusion des retards de congestion, la compagnie aérienne peut choisir le réseau point à point lorsque la désutilité des services avec une escale, engendrée par le temps supplémentaire du voyage, est relativement faible. Deuxièmement, sans tenir compte des investissements fixes de la compagnie aérienne dans le développement d’un aéroport de hub, le réseau 2-hub dominera les trois autres structures de réseau aussi longtemps que cela sera possible, car il implique la différenciation horizontale des produits sur plus de marchés que les trois autres structures de réseau. Le troisième chapitre, écrit conjointement avec Wanjun Yao et Shigeyuki Hamori, trouve empiriquement que l’efficacité de l’allocation des terres plus élevée améliore la productivité des terres moyenne de 29,1% et la plus grande taille de la ferme opérationnelle moyenne réduit la productivité des terres moyenne de 9,2%, ce qui implique que la commercialisation des terres agricoles en Chine améliore finalement la productivité des terres moyenne de 19,9%
This thesis consists of three self-contained papers, each of which corresponds to one chapter. The first chapter, jointly written with Estelle Malavolti, studies the optimal design of delay reduction contract signed between an ANSP and a monopoly airline. In the contract design, we mainly consider the adverse selection problem. Moreover, we conduct comparative-static analysis to study the effects of safety standard and flight frequency on optimal contracts. Besides, we use numerical examples to study when a welfare-maximizing ANSP has to use public funds to provide the service. The second chapter investigates the dual roles of congestion delays and horizontal product differentiation in airline network choice. I find that, first, because of the inclusion of congestion delays, the airline may choose the point-to-point network even when the extra travel time disutility of one-stop services is relatively low. Second, without considering the airline's fixed investments of developing a hub airport, the 2-hub network will dominate the three other network structures as long as it is feasible, as it involves the horizontal product differentiation in more markets than the three other network structures. The third chapter, jointly written with Wanjun Yao and Shigeyuki Hamori, empirically finds that the higher land allocation efficiency improves the average land productivity by 29.1% and the larger average operational farm size reduces the average land productivity by 9.2%, implying that the agricultural land marketization in China finally improves the average land productivity by 19.9%

La movilidad del transporte en España, en el modo ferroviario de ancho ibérico convencional, ha registrado entre los años 1975 y 2009 un aumento de 130 millones de kms‐tren en el año 1975 a 180 millones de kms‐tren en el año 2009, incluidos el transporte de viajeros y el de mercancías. En el servicio de viajeros, el público exige cada vez mayor rapidez de transporte y comodidad para reducir la duración de los viajes, valorando especialmente el elevado nivel actual de la seguridad ferroviaria y en el servicio de mercancías, además de la seguridad por el valor de las mercancías, el cumplimiento del plazo de transporte, origen ‐ destino, de gran importancia para las empresas. El aumento de recorridos en millones de kms‐tren mencionado ha ido acompañado de un aumento de la velocidad máxima, que ha pasado de 120 km/h en 1975 a 160 km/h en 2009, sucesivamente. Por lo tanto ha aumentado también el riesgo, elevando así el reto para conseguir una disminución de los accidentes. La experiencia en la historia del ferrocarril y muy especialmente en el periodo que se analiza en este estudio 1975‐2009, constata que la seguridad en esta modalidad de transporte esta muy relacionada con factores tan importantes como la infraestructura de la vía, la superestructura, los sistemas de gestión, el material y el factor humano, lo que induce al autor a establecer la hipótesis de una correlación entre estos elementos y el nivel de seguridad. El autor de este trabajo, profesional ferroviario que ha desempeñado responsabilidades ejecutivas y directivas, siempre en línea, en la Red Ferroviaria de Interés General Española, y entre ellas la gestión del mantenimiento del material, explotación, investigación de causas de accidentes y su prevención, estima poseer la formación y experiencia suficiente, para estudiar y analizar si los avances tecnológicos y operativos están detrás (o son la causa) de la evolución positiva registrada, como consta en las aportaciones realizadas a lo largo de la vida profesional, recogidas en la bibliografía de la tesis. El objeto del estudio es establecer la correlación que pueda existir entre la notable reducción de accidentes registrados en la Red Ferroviaria de Interés General, en el período, 1975‐2009 y las aplicaciones tecnológicas realizadas al objeto de identificar cuáles han tenido un impacto mayor, en la mejora de la seguridad. El interés de este conocimiento de nivel elevado basado en la experiencia de RENFE y en un periodo de 35 años, no solo es académico ya que la seguridad requiere un esfuerzo continuado y porque el nivel elevado de seguridad alcanzado por RENFE y la mayoría de Operadores Ferroviarios Europeos, no se ha alcanzado por otros Operadores. Los accidentes recientes en la estación de Once, próxima a Buenos Aires y la de Chalupki en Polonia, indican que todavía queda mucho por hacer y entendemos, que las conclusiones objetivas de este trabajo serán de extraordinaria utilidad para aquellos otros Operadores que a diferencia de RENFE, tienen todavía mucho que realizar en el campo de la seguridad.
The transport mobility in Spain , in the Iberian gauge rail so conventional, recorded between 1975 and 2009 an increase of 130 million kms- train in 1975 to 180 million train kms- 2009, including passenger transport and freight. In passenger service, the public demands rapidly growing transport and comfort to reduce travel time, especially valuing the present high level of railway safety and freight service, and security for the value of goods, transport term compliance, origin - destination of great importance for companies. The increase of route million train kms- mentioned has been accompanied by an increase in speed, which has grown from 120 km / h in 1975 to 160 km / h in 2009, on. Thus the risk has also increased , raising the challenge to achieve a decrease in accidents. Experience in railroad history and especially in the period analyzed in this study 1975-2009 , notes that security in this mode of transport is closely related to important factors such as road infrastructure, the superstructure, the management systems, the material and the human factor, which induces the author to establish the hypothesis of a correlation between these elements and the security level . The author of this work, has played professional railway executive and managerial responsibilities, always online, in General Interest Railway Network Spanish, and management including maintenance of equipment, operation, investigation of causes of accidents and their prevention, estimated to have sufficient training and experience, to study and analyze whether technological and operational advances are behind (or are the cause ) of the positive developments, as reflected in the contributions made throughout professional life, reported in the literature of the thesis. The purpose of the study is to establish the correlation that may exist between the significant reduction in accidents in the General Interest Railway Network in the period 1975-2009 and technological applications performed in order to identify which have had a major impact on improved security. The interest of this high level knowledge based on the experience of RENFE and over a period of 35 years, not only is academic since security requires sustained effort and because the high level of safety attained by RENFE and most Railway Operators Europe has not been achieved by other operators. Recent Accidents Eleven station near Buenos Aires and the Chalupki in Poland, indicate that there is still much to do and understand, that the factual findings of this study will be extremely useful for those other operators RENFE unlike, still have much to do in the field of security.

Avui dia un considerable nombre d’infraestructures del transport aeri tenen problemes de congestió. Aquesta situació es veu empitjorada amb l’increment de trànsit existent i amb la seva densitat deguda al sistema de hub i spoke utilitzat per les companyies aèries. Aquesta congestió es veu agreujada puntualment per disminucions de capacitat per causes com la meteorologia. Per mitigar aquests desequilibris, normalment són implementades mesures de gestió del flux de transit aeri (ATFM), sent el retard a l’aeroport d’origen una de les més utilitzades. Assignant retard previ a l’enlairament, el trànsit d’arribada és repartit durant un interval de temps superior i les arribades es distribueixen. Malgrat això, la predicció de quan aquestes reduccions de capacitat es solucionaran una tasca dificultosa. Això comporta que es defineixin regulacions que són més llargues del necessari i per tant, porta a la realització de retard innecessari i al desaprofitament de capacitat. La definició de trajectòries precises ofereix noves oportunitats per gestionar aquests desequilibris. Una tècnica prometedora és la utilització de variacions de velocitat durant el creuer. Generalment, es considera que volar més lent que la velocitat de màxim abast (MRC) no és eficient. En aquesta tesis es presenta una nova aproximació. Quan les aerolínies planifiquen els seus vols, consideren el cost del temps junt amb el del combustible. Per tant, és habitual seleccionar velocitats més ràpides que MRC. Així és possible volar més lent de la velocitat de MRC tot mantenint el mateix consum inicialment planificat. Aquest retard realitzat a l’aire pot ser considerat a la fase pre-tàctica per dividir el retard assignat a un vol en retard a terra i retard a l’aire durant el creuer. Amb aquesta estratègia, el retard és absorbit de manera gradual durant el vol fent servir el mateix combustible que inicialment planificat. Si la regulació es cancel•la abans del que estava planificat inicialment, els vols que estan a l’aire es troben en una situació més favorable per tal de recuperar part del retard. La present tesis es centra en l’estudi d’aquest concepte. En primer lloc, s’ha realitzat un estudi de la relació entre el combustible utilitzat i el temps de vol quan es modifica la velocitat nominal de creuer. A continuació, s’ha definit i analitzat el retard que pot ser realitzat sense incorre en un consum extra de combustible en l’absència i en la presencia de vent. També s’ha considerat i analitza la influència de triar un nivell de vol diferent del planificat inicialment i la utilització de combustible extra per tal d’obtenir major quantitat de retard. Els resultats mostren que per vols de curt i mitja distància, la quantitat de retard realitzable és d’entorn a 5 minuts, aquesta quantitat augmenta a uns 25 minuts per vols de llarg recorregut. El nivell de vol s’ha identificat com un dels paràmetres principals que afecten a la quantitat de retard que pot ser absorbit a l’aire. A continuació es presenta l’aplicació de la tècnica a regulacions d’ATFM realistes, i particularment a ground delay programs (GDP). Per tal de mostrar resultats que siguin significatius, els GDPs implementats en 2006 en el espai aeri nord-americà han sigut analitzats. Han sigut detalladament estudiats escenaris als aeroports de San Francisco, Newark i Chicago. Aquests tres aeroports van ser els que van declarar més GDPs durant el 2006 i per la seva situació geogràfica presenten trànsits amb diferents característiques. Per tal de considerar el trànsit s’ha utilitzat dades de la Federal Aviation Administration i característiques aerodinàmiques i de consum realistes provinents d’Airbus. Finalment, la tesis presenta l’efecte d’utilitzar radis d’exempció en els programes de regulació de trànsit i l’ ús de polítiques de priorització de vols diferents a la utilitzada actualment (ration-byschedule). Per concloure, s’ha realitzat una breu discussió sobre l’impacte d’aquesta estratègia en la gestió del trànsit aeri.
Nowadays, many air transport infrastructures suffer from congestion. This situation is worsened by a continuous increase in traffic, and, traffic density due to hub and spoke systems. Weather is one of the main causes which leads to punctual capacity reduction. To mitigate these imbalances, air traffic flow management (ATFM) initiatives are usually undertaken, ground delay at the origin airport being one of the main ones used. By assigning delay on ground at the departure airport, the arrival traffic is spread out and the arrivals are metered at the congested infrastructure. However, forecasting when these capacity drops will be solved is usually a difficult task. This leads to unnecessarily long regulations, and therefore to the realisation of unnecessary delay and an underuse of the capacity of the infrastructures.The implementation of precise four dimension trajectories, envisaged in the near future, presents new opportunities for dealing with these capacity demand imbalances. In this context, a promising technique is the use of speed variation during the cruise. Generally, it is considered that flying slower than the maximum range speed (MRC) is neither efficient nor desirable. In this dissertation a new approach is presented. When airlines plan their flights, they consider the cost of time along with the cost of fuel. It is therefore common practice to select speeds that are faster than MRC.Thus, it is possible to fly slower than MRC while maintaining fuel consumption as initially planned. This airborne delay can be considered at a pre-tactical phase to divide the assigned air traffic flow management delay between ground and airborne delay. With this strategy, the delay is absorbed gradually during the flight using the same fuel as initially planned, but with the advantage that, if the regulation is cancelled before planned, the flights which are already airborne are in a better position to recover part of their assigned delay.This dissertation focuses on the study of this concept. Firstly, a study of the trade-off existing between fuel consumption and flight time, when modifying the nominal cruise speed, is presented. Secondly, the airborne delay that can be realised without incurring extra fuel consumption is defined and assessed in the absence and presence of wind. The influence of selecting a different flight level than initially planned, and the use of extra fuel consumption to obtain higher delay, are also considered and analysed. Results show that for short and mid-range flights around 5 minutes of airborne delay can be realised, while for longer flights this value increases up to around 25 minutes. The flight level is identified as one of the main parameters which affect the amount of airborne delay realisable.Then, the application of the suggested cruise speed reduction on realistic ATFM initiatives, and, in particular, on ground delay programs (GDP) in the United States, is presented. In order to obtain significant results, the GDPs implemented in North American airspace during 2006 are analysed. Scenarios for San Francisco International, Newark Liberty International and Chicago O'Hare International are studied in detail, as these airports were the ones where the most GDPs were implemented in 2006. In addition, due to their location, they present different traffic behaviours. In order to consider the traffic, Federal Aviation Administration data and the aerodynamics and fuel consumption characteristic form Airbus are used.Finally, the use of radius of exemption in the GPDs and the use of ration policies different from the operative ration-by-schedule, are also analysed. To conclude, a brief discussion about the impact of this speed reduction strategy on the air traffic management is presented.
Hoy en día un número considerable de infraestructuras del transporte aéreo tienen problemas de congestión. Esta situación se ve empeorada por el incremento de tráfico existente y por su densidad producida por el sistema de hub y spoke utilizado por las compañías aéreas. Esta congestión se ve agravada puntualmente por disminuciones de capacidad debidas a causas como la meteorología. Para mitigar estos desequilibrios, normalmente se implementan medidas de gestión del tráfico aéreo (ATFM), siendo el retraso en el aeropuerto de origen una de las más utilizadas. Asignando retraso en tierra previo al despegue, el tráfico de llegada se distribuye durante un intervalo mayor de tiempo y se controlan las llegadas. Pese a esto, la predicción de cuando estas reducciones de capacidad se solventarán es generalmente una tarea compleja. Por esto, se suelen definir regulaciones durante un periodo de tiempo superior al necesario, comportando la asignación y realización de retraso innecesario y el desaprovechamiento de las infraestructuras. La definición de trayectorias precisas permite nuevas oportunidades para gestionar estos desequilibrios. Una técnica prometedora es el uso de variaciones de velocidad durante el crucero. Suele considerarse que volar más lento que la velocidad de máximo alcance (MRC) no es eficiente. En esta tesis se presenta una nueva aproximación. Cuando las aerolíneas planifican sus vuelos consideran el coste del tiempo junto con el del combustible. Por consiguiente, es una práctica habitual seleccionar velocidades mas rápidas que MRC. Así es posible volar mas lento que la velocidad de MRC manteniendo el mismo consumo que el inicialmente planificado. Este retraso realizable en el aire puede ser considerado en la fase pre-táctica para dividir el retraso asignado entre retraso en tierra y retraso durante el crucero. Con esta estrategia, el retraso es absorbido de manera gradual durante todo el vuelo utilizando el mismo combustible que el planificado inicialmente por la compañía. Esta estrategia presenta la ventaja de que los vuelos que están en el aire se encuentran en una situación mas favorable para recuperar parte del retraso que tenían asignado si la regulación se cancela. En primer lugar se ha realizado un estudio de la relación existente entre el combustible usado y el tiempo de vuelo cuando la velocidad de crucero es modificada. A continuación, se ha definido y analizado el retraso que se puede realizar sin repercutir en el consumo en la ausencia y en la presencia de viento. También se ha considerado la influencia de elegir un nivel de vuelo diferente al planificado y el uso de combustible extra para incrementar el retraso. Los resultados muestran que para vuelos de corto y medio alcance, la cantidad de retraso es de en torno a 5 minutos, esta cantidad aumenta a unos 25 minutos para vuelos de largo recorrido. El nivel de vuelo se ha identificado como uno de los parámetros principales que afectan a la cantidad de retraso que puede ser absorbido. Seguidamente se presenta la aplicación de esta técnica en regulaciones de ATFM realistas, y en particular de ground delay programs (GDP). Con el objetivo de mostrar resultados significativos, los GDPs definidos en 2006 en el espacio aéreo norteamericano han sido analizados. Han sido estudiados en detalle escenarios en los aeropuertos de San Francico, Newark y Chicago. Estos tres aeropuertos fueron los aeropuertos que implementaron m´as GDPs en 2006 y por su situación geográfica presentan tráficos con diferentes características. Para considerar el tráfico se han utilizado datos de la Federal Aviation Administration y características aerodinámicas y de consumo provenientes de Airbus. Finalmente, se presenta el efecto de usar radios de exención en los GDPs y el uso de políticas de priorización de vuelos diferentes a la utilizada actualmente (ration-by-schedule). Para concluir se ha realizado una breve discusión sobre el impacto de esta estrategia en la gestión del tráfico aéreo.

Manned missions carried out in the last decades were either close to Earth or short missions. In contrast, Space Agencies future plans include manned exploration missions to asteroids, the Moon and finally Mars. The expected mission durations rise significantly and the greater distance from Earth makes a resupply or rescue mission almost impossible. These future plans make it necessary to develop a new Environmental Control and Life Support System (ECLSS), which ensures the survival of the astronauts for such missions. These frame conditions will impose a high degree of closure and a high reliability for the ECLSS. In this thesis, firstly, the different ECLSS technology/component options are presented, and its suitability for a long duration human spaceflight is analyzed. From all technologies the most promising, regenerative systems for atmosphere, water and waste management are selected in order to examine them as part of a complete ECLSS. Different approaches to evaluate the reliability of complex systems are analyzed. Since the failure of a component within the system does not necessarily lead a failure of the entire ECLSS, as the system is able to compensate for some failures, the Stochastic Dynamic Discrete Simulation (SDDS) method is selected. To carry out an SDDS, a robust and adaptable ECLSS model simulation is required. A new software is developed, based on the simulation tool Environment for Life-Support Systems Simulation and Analysis (ELISSA) from the Institute of Space Systems - University of Stuttgart. As a result of a stochastic simulation a list of failure times is obtained, which can be treated using the Maximum Likelihood Estimation (for parametric models) or the Kaplan-Meier method (for non-parametric models), to define the reliability of the system. The input data required to apply the SDDS are the reliabilities of each possible component of the ECLSS. The reliability of each component is defined by the failure rate or its parts. It can be seen, that the use of redundancies (spare parts) is essential for long duration missions, as the reliability of the system without them after 60 days is lower than 50%. The analysis of all components, including their spare parts, is carried out with the Multi-Opbjective Optimization Problem to achieve a high reliability with the lowest possible mass. Both methodologies, SDDS and MOOP have been implemented creating the user-friendly new software RELISSA. Finally, as an example, RELISSA is used to analyze a manned Mars mission. With this analysis, technologies currently in use (on board ISS) are compared with new technologies (currently under development), with the potential to reduce the system mass. The results clearly show that the new technologies can significantly reduce the mass of the system, for results of similar reliability. With these results, the need of development efforts of ECLSS technologies for manned missions beyond Low Earth Orbit is corroborated.
Les missions tripulades realitzades en les últimes dècades, van ser missions properes a la Terra o de curta durada. Per contra, els plans futurs de les Agències Espacials inclouen missions d'exploració tripulades a asteroides, la Lluna o Mart. La durada esperada d'aquestes missions s'incrementa significament i la major distància de la Terra fa que una missió d’abastiment o rescat sigui pràcticament impossible. Aquests futurs plans fan necessari el desenvolupament d'un nou Sistema de Control Ambiental i Suport a la Vida (ECLSS - Environmental Control and Life Support System), que asseguri la supervivència dels astronautes per a aquestes missions . Aquestes condicions imposen un alt nivell de tancament del sistema i una alta fiabilitat per al ECLSS. En aquesta tesi, es presenten les diferents opcions tecnològiques, components i s’analitza la seva viabilitat per a missions tripulades de llarga durada. De totes les tecnologies, se seleccionen els sistemes regeneratius més prometedors per a la gestió de l’atmosfera, l'aigua i els residus, per tal d'analitzar-los com a part de l'ECLSS. S'analitzen diferents mètodes per tal d'avaluar la fiabilitat de sistemes complexos . Com que la fallada d'un component del sistema no implica necessàriament una fallada de tot l'ECLSS, ja que el sistema és capaç de compensar algunes fallades, se selecciona el mètode de simulació dinàmica- estocàstica (SDDS - Stochastic Dynamic Discrete Simulation). Per a dur a terme l'SDDS, es necessita un model de simulació ECLSS robust i adaptable. Es desenvolupa un nou software, basat en l'eina de Simulació de l'Institut de Sistemes Espacials - Universitat de Stuttgart, Environm ent for Life-Support Systems Simulation and Analysis (ELISSA). Com a resultat de la simulació estocàstica, s'obté una llista de temps de fallada, a partir de la qual, amb el mètode de Màxima Versemblança (per a models paramètrics ) o de Kaplan-Meier (per a models no paramètrics ) es defineix la fiabilitat del sistema. Les dades d'entrada necessàries per aplicar l'SDDS són les fiabilitats de cada un dels possibles com ponents de l'ECLSS. La fiabilitat de cada component es defineix a partir de la taxa de fallada de les seves parts. Es pot observar que l'ús de redundàncies (peces de recanvi) és essencial per a missions de llarga durada, ja que la fiabilitat del sistema sense recanvis disminueix més del 50% passats 60 dies. L'anàlisi de tots els components, incloent-hi les peces de recanvi, es realitza a partir del problema d'optimització d'objectius múltiples (MOOP - Multi-Opbjective Optimization Problem ), per tal d'obtenir una altra fiabilitat amb la menor massa possible. Les dues metodologies , SDDS i MOOP, s'han implementat creant un nou software, user-friendly, RELISSA. Finalment, com exemple, s'ha utilitzar RELISSA per analitzar una missió tripulada a Mart. Amb aquesta anàlisi es comparen tecnologies actualment en ús (a l'Estació Espacial Internacional) i noves tecnologies (actualment en desenvolupament) amb el potencial de reduir la massa del sistema. Els resultats mostren clarament que les noves tecnologies poden reduir significament la massa dels sistema, per a resultats similars de fiabilitat. Amb aquests resultats, es corrobora la necessitat de dedicar esforços de desenvolupament en tecnologies ECLSS per a missions tripulades més enllà de l'òrbita baixa terrestre (LEO - Low Earth Orbit).

Transport is one of the basic needs of a functioning society. Unfortunately, transport also pollutes our cities and release greenhouses gases. Driverless technology is a technology predicted to disrupt the future transport system, and perhaps change how we travel from private cars to shared vehicles. This study focuses on the aspect of privately owned versus shared driverless vehicles, to create more knowledge of how the future transport system will look. A utility-based demand model is used to find the demand for private and shared transport when driverless vehicles are available. The utility of different transport options is estimated by looking at earlier studies about the performance of driverless cars, driverless buses and shared driverless taxis, which is used as input for the utility model. The results indicate that driverless technology will not be a catalyst that makes transport go from private to shared. While driverless buses can improve public transport, and shared driverless taxis outcompete current taxis, driverless technology will also improve private vehicles. The results in this study imply that the sustainability improvements earlier reports have predicted with a high use of shared driverless transportation might not materialise unless efforts are done to increase use of shared transportation.
Transport är ett av de grundläggande behoven för ett välfungerande samhälle. På samma gång släpper transporter ut både växthusgaser och skadliga partiklar. Självkörande teknik är något som förväntas revolutionera framtidens transportsystem, förhoppningen är att de ska förändra hur folk reser från privata bilar till delade transporter. Denna studie fokuserar på den förhoppningen. Kommer framtidens transporter ske i privata självkörande fordon eller delade självkörande fordon och vad i sin tur betyder det för framtidens transportsystem? Med en nyttobaserad efterfråge- och bilinnehavsmodell modelleras efterfrågan av självkörande delade taxis, självkörande bussar och självkörande privatbilar. Resultaten indikerar att självkörande teknik inte nödvändigtvis kommer vara en katalysator som får människor att sluta äga och använda privatbilar. Självkörande bussar kan göra kollektivtrafiken bättre, och självkörande delade taxibilar kommer troligtvis användas mer än dagens taxis. Men självkörande privatbilar kommer också ha många fördelar, och de som äger dem kommer dessutom troligtvis köra längre sträckor än dagens bilister. Resultatet av denna rapport indikerar därför att de stora förväntningarna som finns på självkörande teknik gällande delade transporter kan vara felaktiga, om inte andra åtgärder också görs för att öka delning. Att delningen inte ökar gör också att de hållbarhetsförbättringar som vissa tidigare rapporter förutspått inte nödvändigtvis kommer ske.

The thesis analyses the effect of an increase in speed on energy consumption, pollutant emissions and railway operating costs. Besides focusing on the direct consequences of speed variation, the analysis also considers the effects of the shift from the conventional railway system to the high-speed system. This change from one system to another is a far-reaching one, as speed is just one of many highly influential parameters that undergo substantial alterations (characteristics of the trains, curve radii, gradients, speed profile, signalling, etc.). Each of the two focal points of the study is given a certain methodological autonomy through the inclusion of its own state of the art (which is presented as the problem is discussed and analysed) and its specific development and modelling. The common aspects are tackled in a preliminary conceptual chapter on high speed and its economic and social effects, and are simultaneously illustrated with reference to example cases. The final sections are devoted to conclusions, future lines of research, and the bibliography. A down-top methodology is used for the analysis in question, based on the events or physical inducers that produce the consumptions and costs. The most suitable indicators for measuring and comparing are determined and analysed in detail, the expounded methodology allowing the indicators to be extracted ¿one by one¿, which not only facilitates selection of the most appropriate indicator in each case, but also makes it possible to analyse in greater detail the reasons for the differences. Among the conclusions, perhaps the most important concerns the enormous variability of the railway¿s energy consumption results, even within each system, due to the differences in train sizes and architectures, propulsion systems, path and utilization coefficients, emission factors, etc. As regards operating costs, the variability of the results is lower, although it is still considerable and also greater than in other modes of transport. On changing from the conventional system to the high-speed system, the consumption and emission differences between electric traction trains are not great. This study shows that, on average, consumptions and emissions are slightly lower in the high-speed system, although the extremely wide range of values means that all kinds of results can be found. In the case of diesel traction, consumptions, and especially emissions, are much higher than those of electric traction at any speed. Emissions in the improved conventional system (using representative values in the calculation) are 11.5% higher than those of the high-speed system, while those of the conventional system with electric traction and diesel traction are 53.3% and 4.2 times higher, respectively. An increase in rail speed has a very significant effect on the whole corridor (taking all modes of transport into consideration).
La tesis pretende analizar el efecto del incremento de la velocidad en el consumo de la energía y en las emisiones de productos contaminantes, así como en los costes de explotación del ferrocarril. No se trata de analizar únicamente el efecto directo de la variación de la velocidad sobre los consumos y sobre los costes, sino también (en ambos campos) el efecto derivado de pasar del sistema ferroviario convencional al sistema de alta velocidad (en las dos versiones de éste que se definirán posteriormente). Ello es relevante por cuanto al pasar de uno a otro sistema, además de un salto importante en la velocidad, cambian muchos otros parámetros muy influyentes (características de los trenes, radios de curva, pendientes, perfil de velocidades, señalización, etc.) El análisis se realizará, por lo tanto, considerando el efecto conjunto de todos los elementos que componen el sistema de alta velocidad (en cada una de sus dos versiones) pero también se aislará el efecto del incremento de la velocidad (manteniendo todos los demás factores constantes). Para ello es necesario realizar unas reflexiones generales sobre la alta velocidad en el ferrocarril y sus aportaciones de valor. Son múltiples los efectos técnicos y económicos que conlleva la variación de la velocidad y la transición del sistema ferroviario convencional al de alta velocidad. De todos ellos, aquí solo se abordarán dos efectos relacionados entre si y que tienen en común que han sido poco estudiados de forma sistemática: 1) el consumo de energía y las emisiones asociadas a la circulación de los trenes; y 2) los costes de explotación. Dadas las características peculiares de cada uno de los dos estudios se les dota de una cierta autonomía metodológica, al incluir su propio estado del arte (que se presenta al ir razonando sobre el análisis del problema y desarrollo del modelo), su desarrollo y modelado específico. Las partes comunes a los dos problemas se abordan en el capítulo conceptual sobre la alta velocidad y sus efectos económicos y sociales; y en el capítulo de aplicación a los casos-ejemplo, que se hace de forma conjunta. Se concluye con sendos capítulos de conclusiones e identificación de futuras líneas de investigación, y con la bibliografía. En un anejo se incluye una terminología específica que ayudará al lector a familiarizarse con ciertas palabras o acrónimos que son empleados en el ambiente ferroviario en el que tienen un significado diferente del que reciben en otros. Es conveniente mencionar que el autor ha dedicado buena parte de su labor investigadora en los últimos años a estos dos temas (consumo de energía y emisiones; y costes de explotación del ferrocarril en general y de alta velocidad en particular). Ello le ha permitido producir una abundante documentación en forma de artículos, libros, capítulos de libros, ponencias en congresos, etc. En la presente tesis se utilizan estos materiales, pero se añaden dos valores fundamentales: la puesta al día de los datos y de las ideas, y (sobre todo) la sistematización y ordenación de las reflexiones contenidas en todos aquellos trabajos. Además se analizan comparativamente –como novedad- los dos sistemas de alta velocidad: el que emplea líneas nuevas con velocidades máximas por encima de los 250 kilómetros por hora, y el que utiliza líneas mejoradas con velocidades del orden de 200 a 220 kilómetros por hora. En cada uno de los dos campos fundamentales de estudio (energía y emisiones, y costes de explotación) se incluye –como se ha indicado- el análisis específico del estado del arte, con especial referencia a otros trabajos previos del autor en los que pueden encontrarse los temas explicados con mayor extensión y detalle. El estado del arte se irá presentando, para mayor simplicidad expositiva, a medida que en cada caso se vaya avanzando en el análisis del problema o en el planteamiento del modelo.

Talking about race cars' aerodynamics, effects that the exhaust system has on the latter can not be ignored. In the past years, engineers take advantage of these high-energy flows which have turned to be the key point in many car competitions. The purpose of this thesis is to identify a methodology for the fluid dynamic simulation of the exhaust gases, in cross-flow configuration, aimed to predict the effect on the car's aerodynamic load through the application of Delayed Detached Eddy Simulations (DDES). Furthermore, it wants to evaluate the differences, in terms of loads and fluid structures, between this model and the Reynolds-averaged Navier–Stokes Eddy Viscosity Model (RANS-EVM). The car considered for the study is the Dallara P217 built by Dallara to compete in the 2017 World Endurance Championship (WEC). The basic hypothesis in DDES modelling is the linearization of the vehicle-exhaust system. The flows inside the exhaust pipes (Sub-Model Simulation) and the external flows outside the car (Full-Model Simulation) were therefore independently simulated. The Full-Model simulation models the exhaust flows through the use of a velocity inlet condition; the data necessary for the definition of this boundary condition are the results coming from the Sub-Model simulation.

Cette thèse s’est construite autour du fait établi que la zone d’embouchure a joué un rôle central dans le développement du delta du Danube et de l’hypothèse selon laquelle les embouchures, étant des pourvoyeurs pour la côte en sédiments et en eau douce, sont essentielles à la compréhension des côtes sous influence d’embouchures. Cette thèse est basée sur des données de terrain, notamment des levés bathymétriques, des mesures de débit fluvial et de décharge sédimentaire, des données de vagues, vents et courants, ainsi que des profils topographiques et des images satellites. Une grande partie de cette thèse est consacrée à l’utilisation de Mike 21/3 by DHI (Danish Hydraulic Institute), un modèle couplant hydrodynamique et vagues. Les résultats montrent une réponse linéaire dans les changements bathymétriques en relation avec l’influence des inondations et des tempêtes, ces changements peuvent être prédits par un index innondation/tempète basé sur le débit fluvial, la décharge sédimentaire et la hauteur des vagues (R^2=0.84). Des simulations de modélisation exploratoire sont développée pour une gamme complète de conditions. La déflexion du jet est prédit en fonction de l’équilibre entre débit fluvial et courant longshore, ainsi le jet sortant est dévié (ou non-dévié) quand le courant longshore est dominant (ou dominé) sur le débit fluvial. Finalement, la thèse esquisse un schéma préliminaire du transport sédimentaire sur le lobe deltaïque de l’embouchure St. Gheorghe et décrit les actions nécessaires pour envisager au complet le système de transport sédimentaire, indispensable à une gestion réussie de cette côte deltaïque
This thesis started from the observation that river mouths play a central role in the development of the Danube Delta and from an intuition that river mouths, as suppliers of sediment and water to coastal areas are quintesential in understanding river-influenced coasts. The present thesis is based on field data which comprises bathymetric surveys, measured river water and solid discharges, wave and wind data, ADCP data, topographic profiles, satellite imagery. Also, a big part of the thesis is dedicated to using the Mike 21/3 by DHI (Danish Hydraulic Institute), a coupled hydrodynamic and wave model.Results show a linear response in bathymetric change in relation to the relative influence of floods and storms and that change can be predicted by a Flood/Storm index based on river water or sediment discharge and wave height proxies (R^2=0.84). Furthermore, the analysis is extended using exploratory modelling to a full range of conditions. Jet deflection is predicted by a balance of river jet discharge and longshore current discharge, such that the jet is deflected (undeflected) when the longshore current is much higher (much lower) than the river jet, and a ~45* deflection is predicted when the discharge of jet equals the discharge of the longshore current.Finally, the thesis sketches a preliminary scheme for the sediment transport at the wave-influenced Sf. Gheorghe lobe, taking into account the known sources and sinks, based on bathymetric measurements and numerical modelling results; and outlines the actions needed to envisage a full sediment transport scheme which is needed for a successful management of the deltaic coast

La implementació dels sistemes de transport intel·ligent (ITS) ha possibilitat disposar de gran quantitat de dades de trànsit en temps real, utilitzant les actuals infrastructures en la xarxa viària que ens permeten recollir informació on-line. Mesures de flux de trànsit, velocitats o ocupació proporcionats pels detectors son un exemple. Com utilitzar les dades de trànsit en temps real, així com les dades històriques, per realitzar una predicció a curt termini és encara un problema obert als investigadors. El problema de la predicció del trànsit a curt termini és determinar l'evolució del flux del trànsit o, de forma equivalent, l'estat de la xarxa. La possibilitat de realitzar una predicció dinàmica de l'estat de la xarxa és essencial per la gestió del trànsit i centres d'informació de trànsit, permetent l'aplicació de polítiques de control o gestió per prevenir les congestions, i evitar el problemes que es deriven quan aquesta congestió ja és present.Els sistemes avançats de gestió de trànsit (ATMS) i sistemes avançats d'informació de trànsit (ATIS) han de considerar en temps real períodes de temps on ni la demanda ni el flux de trànsit son constants ni homogenis. La demanda i el flux tenen un comportament dinàmic, és a dir, son dependents del temps. El concepte de gestió de trànsit, com es defineix en Barceló (1991), té un sentit més ampli que el clàssic concepte de control de trànsit, ja que realitza accions sobre el temps, incloent el control sobre l'espai, com per exemple la redistribució dels fluxos amb accions de "rerouting" proposant rutes alternatives. Com a conseqüència la gestió de trànsit requereix una modelització dinàmica que representi la variació del flux a través del temps. Totes les propostes de sistemes avançats de trànsit i sistemes de control basats en les tecnologies telemàtiques estan d'acord amb la importància de la predicció a curt termini de l'evolució del flux de trànsit, que és equivalent a tenir una predicció a curt termini de l'estat de la xarxa viària per gestionar correctament el trànsit, disseminació de la informació als usuaris, etc. Algunes arquitectures de sistemes han estat proposades i avaluades en projectes Europeus en els darrers anys. Malauradament els resultats obtinguts en aquests projectes no es poden extrapolar o aplicar a estructures urbanes complexes. Altres propostes més adequades a estructures més complexes han estat desenvolupades, com per exemple les referenciades en Cascetta (1993) i Barceló (1997), però aquests models no son massa apropiats en aplicacions totalment dinàmiques i això ens ha portat a explorar altres direccions per cercar un model de predicció adequat. Davant les prometedores capacitats de les xarxes neuronals com a eines útils en la predicció, (Baldi i Hornik, 1995), vàrem decidir explorar aquesta alternativa. Aquest plantejament, basat en l'obtenció de dades de detecció reals combinat amb les matrius OD històriques, determina la predicció a curt termini de la matriu OD, definida per períodes. Aquesta matriu obtinguda com a resultat, pot ser utilitzada com a dada d'entrada en el simulador microscòpic de trànsit i obtenir l'evolució dels fluxos de trànsit, i com a conseqüència, la predicció de l'estat de la xarxa.Considerant aquesta visió dinàmica de la demanda, podem considerar cada element de la matriu O/D com una sèrie temporal, i per tant la predicció d'una matriu OD consisteix en realitzar la predicció de cada component de la matriu, és a dir, la predicció simultània de diverses sèries temporals multivariants. Solucions a aquest problema basades en mètodes de predicció clàssics, com per exemple Box-Jenkins o filtres de Kalman, han estat proposat per diversos autors (Davis, 1993; Davis et al., 1994; Van der Ziipp i Hamerslag, 1996), i aquestes propostes donen bons resultats en infrastructures lineals, com podria ser el cas d'autopistes, però en el cas de xarxes amb una estructura més complexa, com podria ser un xarxa urbana, no està clar si proporcionen resultats acceptables, encara que en alguns del més prometedors casos, (Davis,1994), la càrrega computacional necessària posa en dubte el seu ús en aplicacions en temps real de xarxes d'una mida considerable, fent necessari la cerca d'altres mètodes.Les xarxes neuronals apareixen com a candidates naturals per un model de predicció, amb el valor afegit de la seva estructura fàcilment paral·lelitzable que en el cas d'un sistema en temps real és una característica a tenir en compte. Una altra raó per pensar en la utilització de les xarxes neuronals son els resultats reportats per en Chakraborty (1992) en l'anàlisi de sèries temporals multivariant utilitzant xarxes neuronals, o d'en Weigend (1992) en l'avaluació de les capacitats predictives comparades amb altres models clàssics.La predicció dinàmica de l'estat de la xarxa en termes de predicció de la matriu OD utilitzant Xarxes Neuronals té un inconvenient: la quantitat de dades necessàries per un correcte aprenentatge. El treball de recerca realitzat en aquesta tesis proposa solventar aquest desavantatge particionant la xarxa neuronal amb grups de parells OD "independents" segons la identificació de camins més utilitzats.La predicció a curt termini desemboca d'aquesta forma cap al crític problema de l'Assignació Dinàmica de Trànsit (DTA), que en aquesta tesis és resolta amb una heurística basada en la microsimulació. El treball de recerca planteja un dels aspectes més crítics de la simulació dinàmica de xarxes viàries, anomenat heurística d'assignació dinàmica, amb la consideració dels models de selecció de rutes, i la metodologia de la validació, un aspecte important per determinar el grau de validació i significació dels resultats de simulació. Aquest treball està estructurat en dues parts, la primera ens dóna una visió global de com les principals funcionalitats han estat implementades en el simulador microscòpic AIMSUN, (AIMSUN 2002), i una segona part dedicada a parlar en detall de la heurística dissenyada i determinar una guia en la calibració/validació dels seus paràmetres. Un cop el model de simulació està validat i calibrat, llavors és utilitzat per realitzar el DTA on els seus resultats ens permeten identificar els camins més utilitzats per llavors determinar la partició dels parells OD i així la definició de les xarxes neuronals per la realitzar la predicció.
The implementation of Intelligent Transport Systems (ITS) has made vast quantities of real-time traffic data available, by making use of current road network infrastructure that enables information to be gathered on-line. Detectors that measure traffic flow, speed and occupancy are an example. How to use real-time traffic data, as well as historical data, to provide short-term traffic prediction, remains an open problem for researchers. The problem of short-term traffic prediction involves determining the evolution of traffic flows or, equivalently, of the network state. The ability to predict the network state dynamically is essential in traffic management and for traffic information centres particularly, since it enables them to apply traffic control and traffic management policies to prevent traffic congestion rather than dealing with traffic problems after congestion has already occurred. Advanced traffic management systems (ATMS) and advanced traffic information systems (ATIS) must consider, in real time, short time intervals in which neither demand nor flows are constant and homogenous. Demand and flow behave dynamically, that is, they are both time-dependent. The concept of traffic management, as defined by Barceló (1991), is broader than the classic concept of traffic control, because it takes action over time, including control over space, such as, for instance, redistributing flows by rerouting, that is, by proposing alternatives routes. Therefore, traffic management applications require dynamic modelling that shows flow variation over time.All proposals for advanced traffic management and control systems that are based on telematic technologies agree on the importance of short-term prediction of traffic flow evolution, which is equivalent to the short-term prediction of the network state, for correct decision-making in traffic management, information dissemination to users, etc. Several system architectures have been proposed and evaluated in European projects in recent years. Although the achievements of these projects cannot be applied or extrapolated to complex urban structures, other models that are more suited to complex networks have been developed, by Cascetta (1993) and Barceló (1997), for example. Unfortunately, these models do not appear to be appropriate for full dynamic applications, and so we had to look elsewhere in our search for a suitable prediction model. The promising features of neural networks, which make them suitable for use as predictive tools (Baldi and Hornik, 1995), encouraged us to explore this approach. The approach, which is based on real-time detector measurements combined with historical OD matrices, involves determining a short-term forecast of a sliced OD matrix. The forecast OD matrix could be used as input for a microscopic traffic simulator such as AIMSUN; thus the evolution of traffic flows and, as a consequence, the forecast network state could be obtained.According to this dynamic vision of demand, we can consider each of the OD matrix's components as a time series. Therefore, forecasting an OD matrix consists in performing the forecast for each component in the matrix, that is, in simultaneously forecasting many multivariate time series. Solutions to this problem that are based on classic forecasting methods, such as Box-Jenkins or Kalman filtering, have been proposed by several authors (Davis, 1993; Davis et al., 1994; Van der Ziipp and Hamerslag, 1996). The approaches proposed provide relatively good results for linear infrastructures, such as motorways, although it remains unclear whether they would provide reliable results in the case of more complex networks, such as urban networks. In some of the most promising cases (Davis, 1994), however, the computational task required practically invalidates their use in real-time applications in large-scale networks and makes it advisable to look for other methods. Neural networks appear to be natural candidates for forecasting models, particularly if their easily parallelisable structure is taken into account, and high computational speed is required to achieve a system's objectives. Further reasons to consider a neural network approach are the results reported by Chakraborty (1992) for multivariate time series analysis using neural networks and by Weigend (1992) in his evaluation of their predictive capabilities compared to other classic models.The dynamic prediction of the network state in terms of the OD matrix by means of neural networks has one main drawback: the amount of data required for the proper training of the neural network. This thesis proposes solving this handicap by partitioning the neural network in terms of clusters of independent or almost independent OD pairs. This technique allows an original neural network of a large size to be split into a set of smaller neural networks that are easier to train. Before the clustering problem can be solved, however, the paths that are most likely to be used between each OD pair must be identified.Short-term forecasting leads, in this way, to the critical problem of dynamic traffic assignment, which is solved in this thesis by a microsimulation-based heuristic. In the thesis, some of the most critical aspects of the dynamic simulation of road networks are discussed, namely heuristic dynamic assignment, implied route choice models and the validation methodology, a key issue in determining the degree of validity and significance of the simulation results. The work is divided into two parts: the first provides an overview of how the main features of microscopic simulation were implemented in the microscopic simulator AIMSUN (AIMSUN 2002) and the second is a detailed discussion of heuristic dynamic assignment and sets guidelines for calibrating and validating dynamic traffic assignment parameters. The calibrated and validated simulation model is then used to conduct a dynamic traffic assignment, whose output identifies the paths that are most likely to be used, which will be clustered in subsets that connect the OD pairs and will define the neural networks for the forecast.

La implementació dels sistemes de transport intel·ligent (ITS) ha possibilitat disposar de gran quantitat de dades de trànsit en temps real, utilitzant les actuals infrastructures en la xarxa viària que ens permeten recollir informació on-line. Mesures de flux de trànsit, velocitats o ocupació proporcionats pels detectors son un exemple. Com utilitzar les dades de trànsit en temps real, així com les dades històriques, per realitzar una predicció a curt termini és encara un problema obert als investigadors. El problema de la predicció del trànsit a curt termini és determinar l'evolució del flux del trànsit o, de forma equivalent, l'estat de la xarxa. La possibilitat de realitzar una predicció dinàmica de l'estat de la xarxa és essencial per la gestió del trànsit i centres d'informació de trànsit, permetent l'aplicació de polítiques de control o gestió per prevenir les congestions, i evitar el problemes que es deriven quan aquesta congestió ja és present.
Els sistemes avançats de gestió de trànsit (ATMS) i sistemes avançats d'informació de trànsit (ATIS) han de considerar en temps real períodes de temps on ni la demanda ni el flux de trànsit son constants ni homogenis. La demanda i el flux tenen un comportament dinàmic, és a dir, son dependents del temps. El concepte de gestió de trànsit, com es defineix en Barceló (1991), té un sentit més ampli que el clàssic concepte de control de trànsit, ja que realitza accions sobre el temps, incloent el control sobre l'espai, com per exemple la redistribució dels fluxos amb accions de "rerouting" proposant rutes alternatives. Com a conseqüència la gestió de trànsit requereix una modelització dinàmica que representi la variació del flux a través del temps.
Totes les propostes de sistemes avançats de trànsit i sistemes de control basats en les tecnologies telemàtiques estan d'acord amb la importància de la predicció a curt termini de l'evolució del flux de trànsit, que és equivalent a tenir una predicció a curt termini de l'estat de la xarxa viària per gestionar correctament el trànsit, disseminació de la informació als usuaris, etc. Algunes arquitectures de sistemes han estat proposades i avaluades en projectes Europeus en els darrers anys. Malauradament els resultats obtinguts en aquests projectes no es poden extrapolar o aplicar a estructures urbanes complexes. Altres propostes més adequades a estructures més complexes han estat desenvolupades, com per exemple les referenciades en Cascetta (1993) i Barceló (1997), però aquests models no son massa apropiats en aplicacions totalment dinàmiques i això ens ha portat a explorar altres direccions per cercar un model de predicció adequat. Davant les prometedores capacitats de les xarxes neuronals com a eines útils en la predicció, (Baldi i Hornik, 1995), vàrem decidir explorar aquesta alternativa. Aquest plantejament, basat en l'obtenció de dades de detecció reals combinat amb les matrius OD històriques, determina la predicció a curt termini de la matriu OD, definida per períodes. Aquesta matriu obtinguda com a resultat, pot ser utilitzada com a dada d'entrada en el simulador microscòpic de trànsit i obtenir l'evolució dels fluxos de trànsit, i com a conseqüència, la predicció de l'estat de la xarxa.
Considerant aquesta visió dinàmica de la demanda, podem considerar cada element de la matriu O/D com una sèrie temporal, i per tant la predicció d'una matriu OD consisteix en realitzar la predicció de cada component de la matriu, és a dir, la predicció simultània de diverses sèries temporals multivariants. Solucions a aquest problema basades en mètodes de predicció clàssics, com per exemple Box-Jenkins o filtres de Kalman, han estat proposat per diversos autors (Davis, 1993; Davis et al., 1994; Van der Ziipp i Hamerslag, 1996), i aquestes propostes donen bons resultats en infrastructures lineals, com podria ser el cas d'autopistes, però en el cas de xarxes amb una estructura més complexa, com podria ser un xarxa urbana, no està clar si proporcionen resultats acceptables, encara que en alguns del més prometedors casos, (Davis,1994), la càrrega computacional necessària posa en dubte el seu ús en aplicacions en temps real de xarxes d'una mida considerable, fent necessari la cerca d'altres mètodes.
Les xarxes neuronals apareixen com a candidates naturals per un model de predicció, amb el valor afegit de la seva estructura fàcilment paral·lelitzable que en el cas d'un sistema en temps real és una característica a tenir en compte. Una altra raó per pensar en la utilització de les xarxes neuronals son els resultats reportats per en Chakraborty (1992) en l'anàlisi de sèries temporals multivariant utilitzant xarxes neuronals, o d'en Weigend (1992) en l'avaluació de les capacitats predictives comparades amb altres models clàssics.
La predicció dinàmica de l'estat de la xarxa en termes de predicció de la matriu OD utilitzant Xarxes Neuronals té un inconvenient: la quantitat de dades necessàries per un correcte aprenentatge. El treball de recerca realitzat en aquesta tesis proposa solventar aquest desavantatge particionant la xarxa neuronal amb grups de parells OD "independents" segons la identificació de camins més utilitzats.
La predicció a curt termini desemboca d'aquesta forma cap al crític problema de l'Assignació Dinàmica de Trànsit (DTA), que en aquesta tesis és resolta amb una heurística basada en la microsimulació. El treball de recerca planteja un dels aspectes més crítics de la simulació dinàmica de xarxes viàries, anomenat heurística d'assignació dinàmica, amb la consideració dels models de selecció de rutes, i la metodologia de la validació, un aspecte important per determinar el grau de validació i significació dels resultats de simulació. Aquest treball està estructurat en dues parts, la primera ens dóna una visió global de com les principals funcionalitats han estat implementades en el simulador microscòpic AIMSUN, (AIMSUN 2002), i una segona part dedicada a parlar en detall de la heurística dissenyada i determinar una guia en la calibració/validació dels seus paràmetres. Un cop el model de simulació està validat i calibrat, llavors és utilitzat per realitzar el DTA on els seus resultats ens permeten identificar els camins més utilitzats per llavors determinar la partició dels parells OD i així la definició de les xarxes neuronals per la realitzar la predicció.
The implementation of Intelligent Transport Systems (ITS) has made vast quantities of real-time traffic data available, by making use of current road network infrastructure that enables information to be gathered on-line. Detectors that measure traffic flow, speed and occupancy are an example. How to use real-time traffic data, as well as historical data, to provide short-term traffic prediction, remains an open problem for researchers. The problem of short-term traffic prediction involves determining the evolution of traffic flows or, equivalently, of the network state. The ability to predict the network state dynamically is essential in traffic management and for traffic information centres particularly, since it enables them to apply traffic control and traffic management policies to prevent traffic congestion rather than dealing with traffic problems after congestion has already occurred.
Advanced traffic management systems (ATMS) and advanced traffic information systems (ATIS) must consider, in real time, short time intervals in which neither demand nor flows are constant and homogenous. Demand and flow behave dynamically, that is, they are both time-dependent. The concept of traffic management, as defined by Barceló (1991), is broader than the classic concept of traffic control, because it takes action over time, including control over space, such as, for instance, redistributing flows by rerouting, that is, by proposing alternatives routes. Therefore, traffic management applications require dynamic modelling that shows flow variation over time.
All proposals for advanced traffic management and control systems that are based on telematic technologies agree on the importance of short-term prediction of traffic flow evolution, which is equivalent to the short-term prediction of the network state, for correct decision-making in traffic management, information dissemination to users, etc. Several system architectures have been proposed and evaluated in European projects in recent years. Although the achievements of these projects cannot be applied or extrapolated to complex urban structures, other models that are more suited to complex networks have been developed, by Cascetta (1993) and Barceló (1997), for example. Unfortunately, these models do not appear to be appropriate for full dynamic applications, and so we had to look elsewhere in our search for a suitable prediction model. The promising features of neural networks, which make them suitable for use as predictive tools (Baldi and Hornik, 1995), encouraged us to explore this approach. The approach, which is based on real-time detector measurements combined with historical OD matrices, involves determining a short-term forecast of a sliced OD matrix. The forecast OD matrix could be used as input for a microscopic traffic simulator such as AIMSUN; thus the evolution of traffic flows and, as a consequence, the forecast network state could be obtained.
According to this dynamic vision of demand, we can consider each of the OD matrix's components as a time series. Therefore, forecasting an OD matrix consists in performing the forecast for each component in the matrix, that is, in simultaneously forecasting many multivariate time series. Solutions to this problem that are based on classic forecasting methods, such as Box-Jenkins or Kalman filtering, have been proposed by several authors (Davis, 1993; Davis et al., 1994; Van der Ziipp and Hamerslag, 1996). The approaches proposed provide relatively good results for linear infrastructures, such as motorways, although it remains unclear whether they would provide reliable results in the case of more complex networks, such as urban networks. In some of the most promising cases (Davis, 1994), however, the computational task required practically invalidates their use in real-time applications in large-scale networks and makes it advisable to look for other methods.
Neural networks appear to be natural candidates for forecasting models, particularly if their easily parallelisable structure is taken into account, and high computational speed is required to achieve a system's objectives. Further reasons to consider a neural network approach are the results reported by Chakraborty (1992) for multivariate time series analysis using neural networks and by Weigend (1992) in his evaluation of their predictive capabilities compared to other classic models.
The dynamic prediction of the network state in terms of the OD matrix by means of neural networks has one main drawback: the amount of data required for the proper training of the neural network. This thesis proposes solving this handicap by partitioning the neural network in terms of clusters of independent or almost independent OD pairs. This technique allows an original neural network of a large size to be split into a set of smaller neural networks that are easier to train. Before the clustering problem can be solved, however, the paths that are most likely to be used between each OD pair must be identified.
Short-term forecasting leads, in this way, to the critical problem of dynamic traffic assignment, which is solved in this thesis by a microsimulation-based heuristic. In the thesis, some of the most critical aspects of the dynamic simulation of road networks are discussed, namely heuristic dynamic assignment, implied route choice models and the validation methodology, a key issue in determining the degree of validity and significance of the simulation results. The work is divided into two parts: the first provides an overview of how the main features of microscopic simulation were implemented in the microscopic simulator AIMSUN (AIMSUN 2002) and the second is a detailed discussion of heuristic dynamic assignment and sets guidelines for calibrating and validating dynamic traffic assignment parameters. The calibrated and validated simulation model is then used to conduct a dynamic traffic assignment, whose output identifies the paths that are most likely to be used, which will be clustered in subsets that connect the OD pairs and will define the neural networks for the forecast.

In this study the patterns of sediment transport and deposition in the channels and receiving basin of a crevasse splay in the modern Mississippi River delta are examined, with emphasis on the development of a distributary mouth bar. Simultaneous hydroacoustic and optical measurements on the mouth bar show that the bar conforms to the progradational stage of an existing conceptual model of mouth bar development. This is confirmed by cores dated using Beryllium-7, which provides a record of the deposition on the bar over a 90-day period. Stratigraphic data from cores obtained on the bar are used to extend the conceptual model to account for variable riverine inputs. A numerical model, developed and validated using field data is capable of representing the fundamental sedimentary processes responsible for mouth bar progradation. These results will be of interest to coastal geologists, engineers and coastal managers alike.

Bicycles are one of the most efficient way to travel within short-distance trips due to its relatively low maintenance and operation costs (Gao, Liu, & Feng, 2012). Besides to their efficiency, bicycles provide more flexibility for their parking and its ease of use. With the increasing transportation demand in major cities, transportation authorities will encourage to use the bicycle more. However, accommodating bicycles would require physical road geometry modifications such as introducing dedicated bicycle-lanes. Cycling appears to be a sustainable form of transportation across virous countries in Europe, as a result the authorities are planning and implementing upgrades to make the transportation system safer, convenient and sustainable which is necessary to encourage more people to use bicycles as a form of transportation. This thesis is a case study which examines current traffic conditions on a bus stop at Långholmsgatan in the city of Stockholm, Sweden and evaluates the effects of different designs for bicycles and buses. At this bus stop in Långholmsgatan, the bicycle lane is located to the right of the traffic road and to the left of the bus stop in the upstream direction. Buses need to cross the bicycle lane in order to arrive and departure the bus stop. Consequently, a conflict will also be created between bicycles and buses that are crossing the bicycle lane. In this thesis, an alternative design is evaluated in which buses and bicycles are separated from each other. However, this will result in a new conflict between bicycles and pedestrians. These two designs are evaluated in terms of travel time and delay and the analysis was done using micro-simulation software VISSIM. The study shows that the current design at the bus stop of Långholmsgatan should be preferred over the alternative design when considering travel time and delay for bicycles. If buses should be considered, the alternative design should be preferred over the current design.

Les technologies réseau qui font fonctionner Internet ont beaucoup évolué depuis ses débuts, mais il y a un aspect de la performance des réseaux qui a peu évolué : la latence. En 25 ans, le débit disponible en couche physique a augmenté de 5 ordres de grandeur, tandis que la latence s'est à peine améliorée d'un ordre de grandeur. La latence est en effet limitée par des contraintes physiques fortes comme la vitesse de la lumière.Cette évolution différenciée du débit et de la latence a un impact important sur la conception des protocoles et leur performance, et notamment sur les protocoles de transport comme TCP. En particulier, cette évolution est indirectement responsable du phénomène de "Bufferbloat" qui remplit les tampons des routeurs et exacerbe encore davantage le problème de la latence. De plus, les utilisateurs sont de plus en plus demandeurs d'applications très réactives. En conséquence, il est nécessaire d'introduire des nouvelles techniques pour réduire la latence ressentie par les utilisateurs.Le but de cette thèse est de réduire la latence ressentie en utilisant des mécanismes de bout en bout, par opposition aux mécanismes d'infrastructure réseau. Deux mécanismes de bout en bout sont proposés. Le premier consiste à multiplexer plusieurs messages ou flux de données dans une unique connexion persistante. Cela permet de mesurer plus finement les conditions du réseau (latence, pertes de paquet) et de mieux s'y adapter, par exemple avec de meilleures retransmissions. J'ai appliqué cette technique à DNS et je montre que la latence de bout en bout est grandement améliorée en cas de perte de paquet. Cependant, en utilisant un protocole comme TCP, il peut se produire un phénomène de blocage en ligne qui dégrade les performances. Il est possible d'utiliser QUIC ou SCTP pour s'affranchir de ce problème.Le second mécanisme proposé consiste à exploiter plusieurs chemins, par exemple du Wi-Fi, une connexion filaire, et de la 4G. L'idée est d'utiliser les chemins de faible latence pour transporter le trafic sensible en priorité, tandis que le reste du trafic peut profiter de la capacité combinée des différents chemins. Multipath TCP implémente en partie cette idée, mais ne tient pas compte du multiplexage. Intégrer le multiplexage donne davantage de visibilité au scheduler sur les besoins des flux de données, et permettrait à eux-ci de coopérer. Au final, on obtient un problème d'ordonnancement qui a été identifié très récemment, "l'ordonnancement multi-chemins sensible aux flux". Ma première contribution est de modéliser ce problème. Ma seconde contribution consiste à proposer un nouvel algorithme d'ordonnancement pour ce problème, SRPT-ECF, qui améliore la erformances des petits flux de données sans impacter celle des autres flux. Cet algorithme pourrait être utilisé dans une implémentation de MPQUIC (Multipath QUIC). De façon plusgénérale, ces résultats ouvrent des perspectives sur la coopération entre flux de données, avec des applications comme l'agrégation transparente de connexions Internet
The network technologies that underpin the Internet have evolved significantly over the last decades, but one aspect of network performance has remained relatively unchanged: latency. In 25 years, the typical capacity or "bandwidth" of transmission technologies has increased by 5 orders of magnitude, while latency has barely improved by an order of magnitude. Indeed, there are hard limits on latency, such as the propagation delay which remains ultimately bounded by the speed of light.This diverging evolution between capacity and latency is having a profound impact on protocol design and performance, especially in the area of transport protocols. It indirectly caused the Bufferbloat problem, whereby router buffers are persistently full, increasing latency even more. In addition, the requirements of end-users have changed, and they expect applications to be much more reactive. As a result, new techniques are needed to reduce the latency experienced by end-hosts.This thesis aims at reducing the experienced latency by using end-to-end mechanisms, as opposed to "infrastructure" mechanisms. Two end-to-end mechanisms are proposed. The first is to multiplex several messages or data flows into a single persistent connection. This allows better measurements of network conditions (latency, packet loss); this, in turn, enables better adaptation such as faster retransmission. I applied this technique to DNS messages, where I show that it significantly improves end-to-end latency in case of packet loss. However, depending on the transport protocol used, messages can suffer from Head-of-Line blocking: this problem can be solved by using QUIC or SCTP instead of TCP.The second proposed mechanism is to exploit multiple network paths (such as Wi-Fi, wired Ethernet, 4G). The idea is to use low-latency paths for latency-sensitive network traffic, while bulk traffic can still exploit the aggregated capacity of all paths. This idea was partially realized by Multipath TCP, but it lacks support for multiplexing. Adding multiplexing allows data flows to cooperate and ensures that the scheduler has better visibility on the needs of individual data flows. This effectively amounts to a scheduling problem that was identified only very recently in the literature as "stream-aware multipath scheduling". My first contribution is to model this scheduling problem. As a second contribution, I proposed a new stream-aware multipath scheduler, SRPT-ECF, that improves the performance of small flows without impacting larger flows. This scheduler could be implemented as part of a MPQUIC (Multipath QUIC) implementation. More generally, these results open new opportunities for cooperation between flows, with applications such as improving WAN aggregation

In the broiler industry, chicks are often deprived of feed and water up to 48 h posthatch. This delayed access to feed (DAF) has been found to inhibit small intestinal development, compromising growth of the chick. To further understand the impact of DAF on small intestines at the molecular level, many developmental genes that regulate intestinal development were investigated. The objective of this study was to determine the effect of DAF on early posthatch broiler small intestinal morphology, which includes villus height (VH) and crypt depth (CD), and to quantify changes in regulatory genes, such as Olfactomedin 4 (Olfm4), Marker of Ki-67 (Ki-67), Peptide Transporter 1 (PepT1), and Mucin 2 (Muc2), in response to DAF. The Olfm4 mRNA can clearly identify stem cells in the intestinal crypt, which allows VH and CD to be measured, while Ki-67 marks the proliferating cells. The peptide transporter PepT1 is located on intestinal epithelial cells and plays a critical role in transporting di- and tripeptides. Muc2, which is secreted from goblet cells, forms mucus that lines the intestinal epithelial cells acting as a layer of protective coating. Cobb 500 chicks, hatching within a 12 h window, were randomly allocated into three experimental groups: control with no feed delay (ND), 24 h feed delay (D24), and 36 h feed delay (D36). Quantification of Olfm4, Ki-67, PepT1, and Muc2 mRNA abundance were investigated by quantitative PCR, in duodenum, jejunum, and ileum at 0 h, 24 h, 36 h, 72 h, 120 h, and 168 h posthatch. Additionally, localization of cells expressing each gene was visualized using in-situ hybridization at all listed times except 168 h posthatch. Statistical analysis was performed using JMP Pro 14, and significant differences between treatments within a collection day were determined by t-test and one-way ANOVA (P < 0.05). In the ND group, duodenal CD at 0 h was greatest compared to all other time points. With DAF, the duodenal VH of D36 chicks was lower at 36 h (P < 0.001) and 72 h (P = 0.002) compared to ND chicks. In the jejunum and ileum, the VH of D36 chicks was lower at 120 h (P = 0.005) and 72 h (P = 0.03), respectively, compared to ND chicks. In contrast, the VH of D24 chicks at 24 h was greater than ND (P = 0.004) in the jejunum. There was no difference between treatments by 168 h in all intestinal segments. The CD was also lower in DAF groups compared to ND but only in the jejunum and ileum. In contrast, duodenal CD was greater in D24 chicks at 24 h (P = 0.039) and in D36 chicks at 36 h (P < 0.0001) compared to ND chicks, but the difference was no longer significant by 72 h. The VH/CD ratio was lower in all three segments, except the ileum displayed a greater VH/CD ratio in D24 and D36 chicks at 24 h and 36 h, respectively, compared to ND chicks. The mRNA abundance of Olfm4 and Ki-67 was greater in DAF groups upon refeeding, but not until 120 h. The PepT1 mRNA abundance was greater in DAF groups while the abundance of Muc2 mRNA was lower. This difference in mRNA abundance level was more prominent in the duodenum and jejunum. From the analysis of number and distribution of goblet cells found in the upper half and lower half of the villi, expressed as a ratio (VU/VL), a greater ratio was observed in delayed groups compared to ND. In summary, while DAF resulted in altered small intestinal morphology with an effect more pronounced in D36 than D24 chicks, upon refeeding, some genes important to intestinal development were upregulated as a response to the treatment.
Master of Science

Le reseau aerien actuel est compose d'un ensemble de segments qui s'intersectent en des points particuliers definis par des balises emettant des signaux a partir du sol. Ce reseau conduit a un exces des distances parcourues par les avions estime a 8% en europe. Or il est desormais possible grace aux systemes de type gps de concevoir un nouveau reseau independant de moyens au sol. Dans ces conditions, un nouveau reseau aerien pourrait integrer d'une part des lignes aeriennes en ligne droite entre les aeroports et d'autre part la possibilite donnee aux avions de changer de niveau une ou plusieurs fois entre l'origine et la destination en des points pre-definis, afin d'eviter les points de conflit potentiel. Dans cette these, nous presentons principalement des problemes combinatoires sur les ensembles de segments, lies a la conception d'un reseau de ce type. Nous proposons des heuristiques pour le probleme de la clique maximum, de la coloration, de la coloration avec n couleurs d'un ensemble de segments, et un algorithme pour la coloration des segments par portion avec 2 couleurs. Nous proposons ensuite des indicateurs tres simplifies nous permettant d'evaluer facilement la charge de l'espace aerien et la quantite de conflits generees par le deplacement des avions sur nos reseaux. Dans ce cadre, nous effectuons une modelisation des retards au decollage par une loi log-normale et nous adaptons un modele de conflit existant. Finalement, nous donnons des resultats sur des donnees reelles du trafic aerien europeen representant jusqu'a 50% des flux.

La presente tesis doctoral se presenta en forma de compendio de publicaciones, en la cual se han desarrollado diversos Modelos Causales para ayudar en la toma de decisiones usando como herramienta principal las relaciones causa-efecto inherente del sistema. A continuación se describen brevemente los artículos incluidos en la tesis doctoral El artículo titulado “A CD&CR causal model based on path shortening/path stretching techniques” publicado por la revista Transportation Research Part C: Emerging Technologies esta enfocado hacia la investigación académica de alto nivel que aborda el desarrollo, las aplicaciones y consecuencias, de las nuevas tecnologías en el campo del transporte. El enfoque del modelo causal desarrollado en Redes de Petri Coloreadas aportan no solo una metodología innovativa per se, sino que su aplicación e implicaciones en la etapa de planificación, diseño, y gestión, es de particular interés en el rendimiento general del sistema de transporte aéreo. En artículo titulado "Revisiting the pallet loading problem using a discrete event system approach to minimise logistic costs” publicado en la revista International Journal of Production Research (IJPR) se presenta un modelo orientado a eventos discretos para abordar el Problema del Palletizado (PLP) usando como formalismo de especificación las Redes de Petri Coloreadas. El problema de Paletizado conforma una parte fundamental en el flujo logístico de diversos sistemas de transporte (terrestre o aéreo), siendo un factor clave en etapas aguas arriba (e.g. producción) y abajo del sistema (e.g. distribución). El trabajo presenta una novedosa forma de modelado con una importante mejora de los kPI’s respecto a los actuales entornos comerciales, soportando tanto diferentes heurísticas así como su integración con el sistema para encontrar configuraciones óptimas para el acomodo de cajas con una tipología diversa. El artículo denominado "Integrating and sequencing flows in terminal maneuvering area by evolutionary algorithms," publicado por la IEEE/AIAA en el Digital Avionics Systems Conference (DASC), 2011 presenta una aproximación innovadora para aliviar el problema de congestión en el espacio aéreo terminal (terminal maneouvering área). En este artículo se analiza un procedimiento alternativo para la integración y secuenciación de las aeronaves en la fase de aterrizaje. El artículo ha recibido diversas menciones tal como el mejor artículo de la sesión, mejor artículo en la sección de mejoras a la capacidad del sector aéreo y mejor artículo de estudiante. Estas menciones indican la importancia y trascendencia de dicho trabajo donde se utilizan algoritmos desarrollados para la optimización de sistemas altamente complejos como es el espacio aéreo terminal. El artículo que lleva por nombre “A TMA 4DT CD/CR causal model based in path shortening/path stretching techniques”, publicado en el International Conference on Research in Air Transportation — ICRAT 2010, ha recibido la mención Best paper award reconociendo las aportaciones del trabajo presentado. El modelo desarrollado en Redes de Petri Coloreadas para la solución de conflictos entre aeronaves presenta resultados experimentales validados mediante simuladores de vuelo de la compañía Aireuropa que permiten validar las trayectorias obtenidas mediante el modelo desarrollado. Finalmente, el articulo Causal model to sequence and merge 4DT flows in TMA, se encuentran publicados en las memorias del International Conference on Application and Theory of Automation in Command and Control Systems ATTACS2011 donde se presenta un algoritmo de solución para la secuencializacion y fusión de flujos de aterrizaje de aeronaves donde se muestra el gran potencial para mejorar de la toma de decisiones usando el espacio de estados de los modelos de RdPC.
The present PhD thesis report has been elaborated as a compendium of publications, in which diverse Causal Models have been developed to assist in the decision making process using a cause-effect relationship approach inherent in the system. A brief description of the items included in the doctoral thesis. The document is organized in four different parts. First, the Chapter called “Basic Notions” introduces the basic notions and a general perspective on the systems approach. Particular interest has been placed in the Discrete-Event Systems approach, presenting the main features of this formalism. The main theory behind the Coloured Petri Nets approach is presented in Section 2.1.1 Different case studies are provided from Chapters 3 to 5. Chapter 3 presents the work named “A CD&CR causal model based on path shortening/path stretching techniques”, which has been accepted for publication in the Journal Transportation Research Part C: Emerging Technologies. This work depicts a groundbreaking approach to alleviate the airspace congestion and to deal with the implications for the planning, design, and management of Air Traffic Control operations. Particular interest has been placed Terminal Manoeuvring Area (TMA) where the traffic conditions impose to take time-critical decisions. Therefore, an appropriate management of arrival operations could alleviate congestion which impacts directly in capacity and efficiency of the overall Air Traffic Management operations. To evaluate the performance of the the resolution strategy to avoid non-efficient procedures, diverse scenarios have been tasted in a busy traffic period at Gran Canaria’s airport. The result obtain contribute with the planning and management of Air Traffic Control operations to increase the overall predictability of the Air traffic, with benefit to airlines and airports, among others. Chapter 4 corresponds to the article "Revisiting the pallet loading problem using a discrete event system approach to minimise logistic costs” published in the International Journal of Production Research (IJPR). This work presents an innovative and challenging modelling approach to optimize the space and distribution of boxes into a pallet, supporting the inherent box diversity (heterogeneous palletizing problems) of present production and distribution logistic systems. The space utilization is modelled as squares that can be fragmentise and de-fragmentise. In a first approach, the state space analysis is performed to evaluate different optimal configurations to load the maximum number of boxes on a rectangular pallet. The second approach implements heuristics to show that acceptable occupancy results can be obtained without requiring the exhaustive evaluation of the different feasible combination. Chapter 5 introduces the work "Integrating and sequencing flows in terminal maneuvering area by evolutionary algorithms" in proceeding of the IEEE/AIAA en el Digital Avionics Systems Conference (DASC), 2011. This work has received three mentions: Best student paper award; Best paper in the ATM Capacity Improvements track award; y Best paper of session award which confirm the transcendence and implications of such approach. This chapter presents a new approach to optimize a set of aircraft planned to land at a given airport. It is proposed to merge the incoming flows from different routes by mean of speed and path changes. Those changes aim to remove conflicts at merging points and to maintain separation of aircraft following the same route link according to their wake turbulence constraint. The optimization criteria are based on the minimum deviation from the initial path planning. This algorithm has been successfully applied to Gran Canaria airport in Spain with real traffic demand samples for which conflict free flow merging is produced smoothly with optimal runway feeding. Finally, Chapter 5 contains the overall conclusions, future work, summary of contributions and complementary publications on the author. The work presented in annex called “Causal model to sequence and merge 4DT flows in TMA” summarizes the development of a decision support algorithm to tackle the merging and sequencing problem within the Terminal Manoeuvring Area (TMA) sector. The algorithm works with multiple landing traffic flows that share the airspace in the same time window. A flexible terminal area route structure is proposed; it eliminates conflicts within the Standard Terminal Arrival (STAR) while traffic is merged prior converging on to the final approach. As a first instance the first come first serve (FCFS) sequence policy will be tasted and later on the sequence will be altered by means of the Constrained Position Shifting (CPS) algorithm. Gran Canaria STAR is used to evaluate the benefits of the proposed model under synthetic traffic; and to determine the spacing buffers the ICAO Separation minima (ICAO DOC-4444) criteria is used as on current methodology. Finally, in Annex, the paper “A TMA 4DT CD/CR causal model based in path shortening/path stretching techniques” introduces the basic ideas behind a discrete event model for Conflict Detection and Conflict Resolution algorithm in a TMA 4D trajectory scenario in presented which focuses mainly on the arrival phase. This model brings a very interesting knowledge about the events that take place in the management of 4DT and their interactions in Gran Canaria TMA to remove non-effective operations, avoid delay propagation between arrivals and optimize the occupancy of the runway. The causal model developed considers different alternative predefined turning points for each flight evaluating path shortening/path stretching of all trajectories upwards the merging point in a TMA.

Este trabalho apresenta uma proposta de solução para compensar o atraso variável, característico de redes IP. O preditor de Smith é tradicionalmente usado para compensar atrasos, mas no caso deste tipo de rede um fator importante que pode degradar o controle do sistema são as grandes variações nos atrasos sofridos pelas mensagens. Para tratar este problema, este trabalho baseia-se na criação de uma estrutura de dados de armazenamento para a saída do preditor de Smith, possibilitando a comparação do valor de saída da planta com o valor adequado guardado na estrutura. Para determinação do valor correspondente, este está associado a um índice calculado com o tempo de roundtrip obtido de informações dos pacotes de dados proveniente da planta. Para se chegar a tal solução, foi analisada nas primeiras seções a influência do atraso em malhas de controle e posteriormente um estudo do estado da arte para tipos de controle sobre redes IP. Ao final é apresentada uma análise experimental, demonstrando resultados promissores da aplicação desta proposta.
This work presents a solution to compensate the varying delay, characteristic of IP networks. The Smith predictor is traditionally used to compensate delays but in this type of networks an other important factor that can destabilize the system is the large jitter of the delay. In order to solve this problem, the solution presented here is based on a data structure to save the output from the model of the plant used by the Smith predictor, that make possible to compare the output from the plant with the corresponding value in the structure. In order to take the correspondent value, it is associated to an index which is calculated with the roundtrip obtained from the informations in the packet arrived from the plant. In order to formulate this solution, it was analised in the first sections the influence of the delay in control systems and then a study of the state of art of the control systems over IP networks. At the end, an experimental analise to demonstrate the good result of the application of this solution is presented.

Hazardous materials are substances that, if not regulated, can pose a threat to human populations and their environmental health, safety or property when transported in commerce. About 1.5 million tons of hazardous material shipments are transported by truck in the US annually, with a steady increase of approximately 5% per year. The objective of this study was to develop a routing tool for hazardous material transport in order to facilitate reduced environmental impacts and less transportation difficulties, yet would also find paths that were still compelling for the shipping carriers as a matter of trucking cost. The study started with identification of inhalation hazard impact zones and explosion protective areas around the location of hypothetical hazardous material releases, considering different parameters (i.e., chemicals characteristics, release quantities, atmospheric condition, etc.). Results showed that depending on the quantity of release, chemical, and atmospheric stability (a function of wind speed, meteorology, sky cover, time and location of accidents, etc.) the consequence of these incidents can differ. The study was extended by selection of other evaluation criteria for further investigation because health risk as an evaluation criterion would not be the only concern in selection of routes. Transportation difficulties (i.e., road blockage and congestion) were incorporated as important factor due to their indirect impact/cost on the users of transportation networks. Trucking costs were also considered as one of the primary criteria in selection of hazardous material paths; otherwise the suggested routes would have not been convincing for the shipping companies. The last but not least criterion was proximity of public places to the routes. The approach evolved from a simple framework to a complicated and efficient GIS-based tool able to investigate transportation networks of any given study area, and capable of generating best routing options for cargos. The suggested tool uses a multi-criteria-decision-making method, which considers the priorities of the decision makers in choosing the cargo routes. Comparison of the routing options based on each criterion and also the overall suitableness of the path in regards to all the criteria (using a multi-criteria-decision-making method) showed that using similar tools as the one proposed by this study can provide decision makers insights in the area of hazardous material transport. This tool shows the probable consequences of considering each path in a very easily understandable way; in the formats of maps and tables, which makes the tradeoffs of costs and risks considerably simpler, as in some cases slightly compromising on trucking cost may drastically decrease the probable health risk and/or traffic difficulties. This will not only be rewarding to the community by making cities safer places to live, but also can be beneficial to shipping companies by allowing them to advertise as environmental friendly conveyors.

LISA (Laser Interferometer Space Antenna) is a joint mission of ESA and NASA, which aims to be the first space-borne gravitational wave observatory. LISA will consist in a constellation of three spacecraft at the vertexes of an equilateral triangle of side 5 million kilometers. The constellation will orbit around the Sun trailing the Earth by some 20 degrees. Each of the spacecraft harbors two proof masses, carefully protected against external disturbances such as solar radiation pressure and charged particles, which ensures they are in nominal free-fall in the interplanetary gravitational field. Gravitational waves will show as differential accelerations between pairs of proof masses, and the main aim of LISA is to measure such acceleration using laser interferometry. The technologies required for the LISA mission are many and challenging. This, coupled with the fact that some flight hardware cannot be tested on ground, led ESA to define a technology demonstrator to test in flight the required critical technologies. This precursor mission is called LISA Pathfinder (LPF). The payload of LISA Pathfinder is the LISA Technology Package (LTP), and will be the highest sensitivity geodesic explorer flown to date. The LISA Technology Package is designed to measure relative accelerations between two test masses in nominal free fall placed in a single spacecraft, since one LISA arm is squeezed from 5 million kilometer to 35 cm. Its success will prove the maturity of the necessary technologies for LISA such as the Optical Metrology System and the Drag Free concept. The differential acceleration reading will be perturbed by identified disturbances, such as thermal fluctuations or magnetic effects. These disturbances are monitored by the Diagnostics Subsystem. The Magnetic Diagnostics System is one of its modules and is a critical subsystem, since magnetic noise is apportioned to 40% of the total noise budget. In this respect, to estimate the magnetic noise contribution, the Magnetic Diagnostics Subsystem will have two main tasks: (1) estimate the magnetic properties of the test masses, i.e., their remanent magnetic moment and susceptibility, and (2) infer the magnetic field and its gradient at the location of the test masses. To this end, the Magnetic Diagnostics Subsystem includes two coils which generate controlled magnetic fields at the locations of the test masses. These magnetic fields will excite the dynamical response of both test masses. Thus, by adequate processing of the kinematic excursions delivered by the interferometer, the magnetic characteristics of the test masses can be estimated within 1% accuracy level. Additionally, the Magnetic Diagnostic Subsystem includes a set of four tri-axial fluxgate magnetometers. However, the magnetic field and its gradient need to be measured at the positions of the test masses and the readouts of the magnetometers do not provide a direct measurement of the magnetic field at these positions. Thus, an interpolation method must be implemented to calculate them. This is a difficult problem, mostly because the magnetometers are too distant from the locations of the test masses (more than 20 cm away) and because there are not sufficient magnetic channels to go beyond a classical linear interpolation method, which yields extremely poor interpolation results. Consequently, in this thesis we present and validate an alternative interpolation method based on neural networks. We put forward its robustness and accuracy in several mission scenarios and we stress the importance of an extensive magnetic testing campaign. Under these assumptions, we deliver magnetic field and gradient estimates with 10% accuracy. Finally, the estimate of the magnetic noise contribution to the total acceleration between the two LPF’s test masses is determined with an accuracy of 15%. This result represents an enhancement of the estimation quality in one order of magnitude with respect to former studies.
LISA (Laser Interferometer Space Antenna) és un missió espacial conjunta de l’ESA i la NASA, que serà el primer detector d’ones gravitacionals a l’espai. LISA consisteix en una constel·lació de tres satèl·lits situats als vèrtexs d’un triangle equilàter de 5 milions de quilòmetres de costat. La constel·lació orbitarà al voltant del Sol seguint la Terra a uns 20 graus. Cada un dels satèl·lits contindrà dues masses de prova, curosament protegides de pertorbacions externes com la pressió de la radiació solar, assegurant que estiguin en una caiguda lliure nominal en el camp gravitacional interplanetari. Les ones gravitacionals creen acceleracions diferencials entre el parell de masses de prova. Així doncs el principal objectiu de LISA és mesurar l’esmentada acceleració utilitzant interferometria làser. Les tecnologies necessàries per LISA són molt exigents. A més, la majoria d’elles no poden ser testejades a la Terra. Per tant, l’ESA va determinar la necessitat de llançar una missió precursora que actués com a demostrador tecnològic, aquesta missió és LISA Pathfinder (LPF). La seva càrrega útil és el LISA Technology Package (LTP) i serà el sensor geodèsic de més alta sensitivitat a l’espai. El LISA Technology Package està dissenyat per mesurar acceleracions diferencials entre dues masses de prova en caiguda lliure situades en un sol satèl·lit, reduint un dels braços de LISA des de 5 milions de quilòmetres fins a 35 cm. L’èxit de la missió suposaria la demostració de la maduresa de les tecnologies necessàries per LISA, com són el Optical Metrology System i el concepte Drag Free. La mesura de l’acceleració diferencial estarà afectada per certes pertorbacions com podrien ser les fluctuacions tèrmiques o els efectes magnètics a l’interior del satèl·lit. Aquestes pertorbacions són monitoritzades pel Subsistema de Diagnòstic. El Subsistema de Diagnòstic Magnètic és un dels seus mòduls i és un sistema crític, perquè el soroll magnètic representa un 40% del soroll total. Amb la finalitat d’estimar la contribució del soroll magnètic, el Subsistema de Diagnostic Magnètic ha de (1) estimar les propietats magnètiques de les masses de prova, i.e., el seu moment magnètic remanent i la seva susceptibilitat, i (2) estimar el camp magnètic i el seu gradient a la posició de les masses de prova. Així doncs, aquest subsistema integra dues bobines per generar camps magnètics a la posició de les masses. Aquests camps magnètics exciten la resposta dinàmica de les dues masses. Finalment, amb el processament de les excursions cinemàtiques proporcionades per l’interferòmetre podem estimar les característiques magnètiques amb una precisió de l’1%. D’altra banda, el Subsistema de Diagnòstic Magnètic també integra 4 magnetòmetres triaxials. No obstant, el camp magnètic i el seu gradient ha de ser mesurat a la posició de les masses de prova i les lectures dels magnetòmetres no estan situades en aquestes posicions. Per tant, cal implementar un sistema d’interpolació. Aquest problema presenta una dificultat especial perquè els magnetòmetres estan situats lluny de les masses de prova (més de 20 cm) i perquè només hi ha mesures magnètiques per realitzar una interpolació de primer ordre. Aquest mètode dóna resultats inacceptables, per tant en aquesta tesi presentem i validem un mètode d’interpolació alternatiu basat en xarxes neuronals. En demostrem la seva robustesa i exactitud en diferents casos i remarquem la importància de disposar d’una extensa campanya de tests magnètics. Sota aquests supòsits, estimem el camp magnètic i el seu gradient amb un error inferior al 10%. Finalment, l’estimat de la contribució del soroll magnètic en la mesura de l’acceleració diferencial de les dues masses de prova es pot determinar amb una exactitud del 15%. Aquest resultat suposa una millora de la qualitat d’estimació en un ordre de magnitud en comparació a estudis previs.

Promising technological applications of two-phase flows in space have captured the increasing interest of the space sector, provoking a strong demand for more fundamental knowledge. Great efforts have been made in recent decades to study the behavior of two-phase flows in low-gravity environments, which is expected to be different than the behavior observed in the presence of gravitational forces. Nevertheless, many phenomena are still poorly understood. The development of any of these new technologies demands a better knowledge of two-phase flows. In this manuscript we address questions regarding the generation of gas-liquid flows and their behavior in conditions relevant for a microgravity environment. In particular, we focus on an air-water mixture formed in a capillary T-junction. To this end, an experimental setup has been designed to accurately control both gas and liquid flow rates. We performed a quantitative characterization on ground of the T-junction, whose operation is robust to changes in gravity level. Its main performance is the generation of bubbles at a regular frequency with small size dispersion. We obtained two working regimes of the T-junction and identified the crossover region between them. Bubble, slug, churn and annular flow regimes have been observed during the experiments and a flow pattern map has been plotted. We present an experimental study on the bubble-slug transition in microgravity-related conditions. In addition, we address questions regarding the existence of a critical void fraction in order for the bubble-slug transition to occur. The gas-liquid flow has been characterized by measuring the bubble generation frequency as well as the bubble and liquid slug sizes. Since bubble dynamics is also expected to be different in the absence of buoyancy, the bubble velocity has also been studied. The mean void fraction appears as one relevant parameter that allows for the prediction of frequency, bubble velocity, and lengths. We propose curves obtained empirically for the behavior of generation frequency, the bubble velocity and the lengths. The dependence of the frequency on the Strouhal dimensionless number has been analyzed. A numerical study of the formation of mini-bubbles in a 2D T-junction by means of the fluid dynamics numerical code JADIM is also presented. Simulations were carried out for different flow conditions, giving rise to results on the bubble generation frequency, bubble velocity, void fraction and characteristic lengths. Numerical results have been then compared with experimental data.

The main objective of this thesis is to determine the possibility to install in the Port of Palma a redistribution centre of Ro-Ro Cargo in the Occidental Mediterranean, and that needs to analyze different partial objectives, that are important for the main objective. - Determination of the different bilateral commercial fluxes between the different coastal countries. - Localization of the production and reception sources that intervene on the bilateral exchange, or of third countries that use those ports to develop their merchant activities. - Analysis of the nowadays short sea shipping routes for Ro-Ro Ships, evaluating the type of ship and her average occupation. - Analysis of the optimization of the existing routes, with new proposals explained on this thesis. - Describe and evaluate the nowadays and projected facilities in the Port of Palma. - Determine the viability of the project with an evaluation methodology proposed by the author, according to the study scenario and based on the partial objectives explained before. As an initial hypothesis we should evaluate the strategic situation that the Port of Palma has on the analysis context, because it is located between the existing routes. In the light of the analysis of all the parameters referred before, the final objective of the thesis is to evaluate, as an alternative of the Occidental Mediterranean Short Sea Shipping, the establishment of a new Hub Port in Palma. We tried to analyze the possibilities of the Port of Palma to become a HUB future port in the hard market of the Short Sea Shipping Lines. On the present paper we tried to analyze the different factors that could affect the situation of a redistribution centre of cargo, considering as positives: - Geographical situation. - Facility of landfalls. - Availability of berths. - Appropriate port facilities. - Complementary developed services. - Touristic centre on a global level. - Possibility to expand the infrastructures in a mid-term period. - Great occupation, great profitability for the shipping companies. - Development of the Magreb countries. As negative aspects, we could find: - Deficit on the development on the Short Sea Shipping Lines. - Very low activity of the Spanish shipping companies on the Short Sea Shipping Lines. - A HUB Port is not a priority for the Port Authority. - Higher trip cost, because of the duration of the layovers. - Longer distance, growth of the combustible costs. - Increase of the speed to maintain the rotation. - Higher crew costs, because of the increase of the occupation. As a result of our analysis we consider that Palma could have, according to its conditions, a pioneer Hub Port for Ro-Ro cargo on the Occidental Mediterranean, advantage that we should use according to the limited development opportunities that has the Port of Palma.
El objetivo principal de la presente tesis es determinar la posibilidad de instalar en el puerto de Palma un centro de redistribución de carga rodada en el Mediterráneo Occidental, para ello es necesario llegar a analizar distintos objetivos parciales imprescindibles para el objetivo principal. - La determinación de los flujos comerciales bilaterales entre los distintos países que componen la cuenca. - Localización de las fuentes de producción o recepción que intervienen en el intercambio bilateral, o de terceros países, que utilizan estos puertos para desarrollar su actividad mercantil. - Análisis de las actuales líneas de corta distancia para buques de carga rodada, valorando el tipo de buque y su ocupación media. - Análisis de optimización de las rutas ya existentes, con nuevas propuestas presentadas en las presente tesis. - Describir y evaluar las infraestructuras actuales y proyectadas en el puerto de Palma. - Determinar la viabilidad del proyecto, mediante una metodología de valoración propuesta por el autor, adecuada al escenario de estudio y basándose en los objetivos parciales indicados anteriormente. Como hipótesis inicial debemos valorar la situación estratégica que el puerto de Palma tiene en el contexto del análisis, ya que se encuentra a medio camino y centrado en las rutas ya existentes. Basándonos en el análisis de todos los parámetros referenciados anteriormente el objetivo final de la presente tesis es valorar, como alternativa al transporte de corta distancia en el Mediterráneo Occidental, la instalación de un puerto Hub en Palma. Durante la elaboración del presente trabajo hemos intentado analizar las posibilidades de que el Puerto de Palma se pueda convertir en un futuro puerto HUB en el duro mercado de las líneas de corta distancia. En el transcurso del trabajo hemos intentado analizar distintos factores que podrían afectar a la instalación de un centro de redistribución de cargas, considerando como positivas: Situación geográfica, facilidad de recalada, disponibilidad de atraques, infraestructuras portuarias adecuadas, servicios complementarios desarrollados, centro turístico a nivel mundial, posibilidad a medio plazo de ampliación de infraestructuras, mayor ocupación, mayor rentabilidad para las navieras, desarrollo de los países del Magreb. En el anverso podríamos considerar: Déficit en el desarrollo de líneas S.S.S., escasa actividad de empresas españolas en líneas de corta distancia, no entrar en las prioridades de la Autoridad Portuaria el desarrollo de un puerto HUB, mayor coste del trayecto, por duración de las escalas, mayor distancia, incremento del coste de combustible, aumento de la velocidad para mantener rotaciones, costes de tripulación mayores al aumentar la ocupación. A raíz de nuestro análisis consideramos que Palma podría albergar, dadas sus condiciones, un puerto HUB para carga rodada pionero en el Mediterráneo Occidental, ventaja que deberíamos aprovechar dadas las escasas oportunidades de desarrollo que tiene el Puerto de Palma. Se deben de citar entre los potenciales factores positivos, la casi inexistencia de flujos comerciales entre países del Magreb, los cuales podrían crecer, mediante la utilización del puerto de Palma como hub intermedio.

Handover performance is critical to support real-time traffic applications in wireless network communications. The longer the handover delay is, the longer an Mobile Node (MN) is prevented from sending and receiving any data packet. In real-time network communication applications, such as VoIP and video-conference, a long handover delay is often unacceptable. In order to achieve better handover performance, Fast Proxy Mobile IPv6 (FPMIPv6) has been standardised as an improvement to the original Proxy Mobile IPv6 (PMIPv6) in the Internet Engineering Task Force (IETF). The FPMIPv6 adopts a link layer triggering mechanism to perform two modes of operation: predictive and reactive modes. Using the link layer triggering, the handover performance of the FPMIPv6 can be improved in the predictive mode. However, an unsuccessful predictive handover operation will lead to activation of a reactive handover. In the reactive mode, MNs still experience long handover delays and a large amount of packet loss, which significantly degrade the handover performance of the FPMIPv6. Addressing this problem, this thesis presents an Enhanced Triggering Mechanism (ETM) in the FPMIPv6 to form an enhanced FPMIPv6 (eFPMIPv6). The ETM reduces the most time consuming processes in the reactive handover: the failed Handover Initiate (HO-Initiate) delay and bidirectional tunnel establishment delay. Consequently, the overall handover performance of the FPMIPv6 is enhanced in the eFPMIPv6. To show the advantages of the proposed eFPMIPv6, a theoretical analysis is carried out to mathematically model the performance of PMIPv6, FPMIPv6 and eFPMIPv6. Extensive case studies are conducted to validate the effectiveness of the presented eFPMIPv6 mechanism. They are carried out under various scenarios with changes in network link delay, traffic load, number of hops and MN moving velocity. The case studies show that the proposed mechanism ETM reduces the reactive handover delay, and the presented eFPMIPv6 outperforms the PMIPv6 and FPMIPv6 in terms of the overall handover performance.