Rozprawy doktorskie na temat „Traffic matrix”

The traffic matrix is essential for many network management tasks because it provides the amount of traffic that flows between every origin-destination (OD) pair in a network. We focus on two traffic matrix problems: compression and estimation. Traffic matrices contain substantial amounts of data because they are collected at short timescales over long periods. We investigate techniques to compress traffic matrices using wavelet transforms, which allows us to isolate common underlying patterns present within traffic matrix datasets. In addition, it is expensive for network operators to measure traffic matrices directly. We demonstrate a new traffic matrix estimation method that is based on using our compressing transforms and methods for sparse estimation. Our estimation method also relies on inexpensive link-level measurements. We assess the performance of our wavelet-based traffic matrix model by testing it on two traffic matrix datasets.
La matrice de trafic est essentielle pour de nombreuses tâches de gestion de réseau parce qu'elle fourni le volume de trafic qui circule entre chaque paire d'origine et destination (OD) dans un réseau. Nous concentrons sur deux problèmes avec la matrice de trafic: la compression et l'estimation. Les matrices de trafic contiennent de grandes quantités de données parce qu'elles sont recueillies à des délais courts pendant de longues périodes. Nous examinons des techniques pour compresser les matrices de trafic en utilisant les transformées en ondelettes, qui nous permet d'isoler les tendances communes dans les matrices de trafic. En plus, il est coûteux pour les opérateurs de réseau de measurer les matrices de traficdirectement. Nous développons une nouvelle méthode pour estimer la matrice de trafic qui est basée sur les transformées en ondelettes et les méthodes d'estimation rares. Notre méthode d'estimation s'appuie également sur le volume de trafic traversant chaque lien dans un réseau, ce qui est peu coûteux de recueillir. Nous évaluons la performance de notre modèle pour la matrice de trafic en le testant sur deux ensembles de données.

An Origin-Destination (OD) traffic matrix provides a major input to the design, planning and management of a telecommunications network. Since the Internet is being proposed as the principal delivery mechanism for telecommunications traffic at the present time, and this network is not owned or managed by a single entity, there are significant challenges for network planners and managers needing to determine equipment and topology configurations for the various sections of the Internet that are currently the responsibility of ISPs and traditional telcos. Planning of these sub-networks typically requires a traffic matrix of demands that is then used to infer the flows on the administrator's network. Unfortunately, computation of the traffic matrix from measurements of individual flows is extremely difficult due to the fact that the problem formulation generally leads to the need to solve an under-determined system of equations. Thus, there has been a major effort f rom among researchers to obtain the traffic matrix using various inference techniques. The major contribution of this thesis is the development of inference techniques for traffic matrix estimation problem according to three different approaches, viz: (1) deterministic, (2) statistical, and (3) dynamic approaches. Firstly, for the deterministic approach, the traffic matrix estimation problem is formulated as a nonlinear optimization problem based on the generalized Kruithof approach which uses the Kullback distance to measure the probabilistic distance between two traffic matrices. In addition, an algorithm using the Affine scaling method is developed to solve the constrained optimization problem. Secondly, for the statistical approach, a series of traffic matrices are obtained by applying a standard deterministic approach. The components of these matrices represent estimates of the volumes of flows being exchanged between all pairs of nodes at the respective measurement points and they form a stochastic counting process. Then, a Markovian Arrival Process of order two (MAP-2) is applied to model the counting processes formed from this series of estimated traffic matrices. Thirdly, for the dynamic approach, the dual problem of the multi-commodity flow problem is formulated to obtain a set of link weights. The new weight set enables flows to be rerouted along new paths, which create new constraints to overcome the under-determined nature of traffic matrix estimation. Since a weight change disturbs a network, the impact of weight changes on the network is investigated by using simulation based on the well-known ns2 simulator package. Finally, we introduce two network applications that make use of the deterministic and the statistical approaches to obtain a traffic matrix respectively and also describe a scenario for the use of the dynamic approach.

This thesis addresses the traffic matrix estimation problem. Knowledge about the origin-destination (OD) traffic matrix (TM) allows us to solve problems in network engineering; the OD traffic matrix gives us a valuable information about who is communicating with whom in a network, at any given time. Traffic analysis, based on detailed packet or flow level measurements, usually not available throughout a large network due to hardware limitations or/and security reasons. An alternative approach is to use mathematical and statistical techniques for the estimation using the incomplete data accessible via SMNP. In my PhD thesis I describe the traffic data collection and, perform a critical evaluation of existing and novel methods for TM estimation on the real and synthetic data, and test the statistical and non-statistical methods. I discuss the weaknesses and strengths of the various methods, and highlight differences in the results for the simulated traffic and the real one obtained from European and American subnetworks. This research also addresses the variability of Internet traffic in backbone networks is essential for the creation of the better traffic model (vital for the estimation techniques), to better plan and manage existing networks, as well as to design next generation networks. I show the difference between the real traffic in high-bandwidth networks with the classic and most commonly used traffic models, propose a high-bandwidth TM simulation technique which can help with the evaluation of the traffic matrix algorithms in the case when the real TM necessary for the algorithms verification is difficult to obtain.
La matrice de trafic Origine Destination représente le volume de trafic entre chaque source et chaque destination sur un réseau. Elle est utile pour le dimensionnement du réseau, la définition du routage, etc. . . Elle ne peut pas être obtenue directement, mais doit au contraire être estimée, par des méthodes le plus souvent statistiques, partir du volume de trafic agrégé sur chacun des liens du réseau. Les méthodes existantes font des hypothèses réductrices sur les modèles de trafic; le trafic est le plus souvent considéré comme stationnaire et poissonnien. Le sujet de cette thèse est de généraliser les techniques existantes pour des modèles de trafic plus réalistes, et de valider les algorithmes proposés sur du trafic réel dans le cas d'un réseaux local et d' un réseau de cœur, utilisant un simulateur des réseaux large bande, développé dans le cadre du projet

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.
Includes bibliographical references (leaves 104-106). Also available in electronic version. Access restricted to campus users.

With the recent widespread deployment of intelligent transportation systems (ITS) in North America there is an abundance of data on traffic systems and thus an opportunity to use these data in the calibration of microscopic traffic simulation models. Even though ITS data have been utilized to some extent in the calibration of microscopic traffic simulation models, efforts have focused on improving the quality of the calibration based on aggregate form of ITS data rather than disaggregate data. In addition, researchers have focused on identifying the parameters associated with car-following and lane-changing behavior models and their impacts on overall calibration performance. Therefore, the estimation of the Origin-Destination (OD) matrix has been considered as a preliminary step rather than as a stage that can be included in the calibration process. This research develops a methodology to calibrate the OD matrix jointly with model behavior parameters using a bi-level calibration framework. The upper level seeks to identify the best model parameters using a genetic algorithm (GA). In this level, a statistically based calibration objective function is introduced to account for disaggregate form of ITS data in the calibration of microscopic traffic simulation models and, thus, accurately replicate dynamics of observed traffic conditions. Specifically, the Kolmogorov-Smirnov test is used to measure the "consistency" between the observed and simulated travel time distributions. The calibration of the OD matrix is performed in the lower level, where observed and simulated travel times are incorporated into the OD estimator for the calibration of the OD matrix. The interdependent relationship between travel time information and the OD matrix is formulated using a Extended Kalman filter (EKF) algorithm, which is selected to quantify the nonlinear dependence of the simulation results (travel time) on the OD matrix. The two test sites are from an urban arterial and a freeway in Houston, Texas. The VISSIM model was used to evaluate the proposed methodologies. It was found that that the accuracy of the calibration can be improved by using disaggregated data and by considering both driver behavior parameters and demand.

A meta do trabalho é propor e testar a hipótese que a contagem de tráfego nas interseções da rede de transportes, ao invés de contagem de tráfego nos arcos, reduz o grau de indeterminação e torna mais precisa a matriz OD estimada pelo modelo sintético. Ademais, é proposto e detalhado um método de estimação da matriz OD através de médias sucessivas (MEMS). É apresentada a descrição matemática das propostas e o detalhamento dos experimentos elaborados para testá-las. Três métodos de estimação, QUEENSOD, TransCAD e MEMS, foram utilizados na verificação da hipótese. A inserção de \"arcos virtuais\" na rede de transportes constituiu um artifício que permitiu aos programas QUEENSOD e TransCAD realizarem a estimação utilizando fluxos observados nas interseções. A utilização de contagens de fluxo nas interseções propiciou à matriz OD estimada, melhorias que acarretaram sua aproximação com a matriz OD \"real\". O experimento mostrou que a matriz OD estimada ao considerar contagens de tráfego nas interseções apresenta melhor desempenho em comparação a matriz estimada ao considerar contagens nos arcos da rede de transportes. A matriz estimada gradativamente aproximou-se da \"real\" à medida que foi aumentada a quantidade de informação de fluxo e sua distribuição na rede. Assim, a hipótese formulada para este trabalho não pôde ser refutada.
The aim of this work is to propose and test the hypothesis that traffic counts collected at network intersections, instead of traffic counts collected at links, reduce indeterminacy and make more accurate the OD matrix estimated by the synthetic model. Furthermore, a method is proposed and described in detail to estimate the OD matrix based on successive averages (MEMS). The model formulation of the proposals and a description of the experiments are presented. Three estimation methods, QUEENSOD, TransCAD, and MEMS were used in the hypothesis verification. The use of \"virtual links\" in the network consists of an artifice that enable the QUEENSOD and TransCAD to estimate the OD matrix based on traffic counts at intersection. By using flow counts conducted at intersections, improvements could be made to the estimated OD matrix bringing it closer to \"real situations\". The experiments results show that the OD matrix estimation based on traffic counts collected on network intersection has a better performance in contrast to the estimation based on traffic counts collected on network links. The estimated matrix gradually becomes closer to \"real situations\" while the quantity of information flow and its distribution to the network is increased. Therefore, the formulated hypothesis for this work cannot be refuted.

This dissertation aims to improve the performance of existing assignment-based dynamic origin-destination (O-D) matrix estimation models to successfully apply Intelligent Transportation Systems (ITS) strategies for the purposes of traffic congestion relief and dynamic traffic assignment (DTA) in transportation network modeling. The methodology framework has two advantages over the existing assignment-based dynamic O-D matrix estimation models. First, it combines an initial O-D estimation model into the estimation process to provide a high confidence level of initial input for the dynamic O-D estimation model, which has the potential to improve the final estimation results and reduce the associated computation time. Second, the proposed methodology framework can automatically convert traffic volume deviation to traffic density deviation in the objective function under congested traffic conditions. Traffic density is a better indicator for traffic demand than traffic volume under congested traffic condition, thus the conversion can contribute to improving the estimation performance. The proposed method indicates a better performance than a typical assignment-based estimation model (Zhou et al., 2003) in several case studies. In the case study for I-95 in Miami-Dade County, Florida, the proposed method produces a good result in seven iterations, with a root mean square percentage error (RMSPE) of 0.010 for traffic volume and a RMSPE of 0.283 for speed. In contrast, Zhou’s model requires 50 iterations to obtain a RMSPE of 0.023 for volume and a RMSPE of 0.285 for speed. In the case study for Jacksonville, Florida, the proposed method reaches a convergent solution in 16 iterations with a RMSPE of 0.045 for volume and a RMSPE of 0.110 for speed, while Zhou’s model needs 10 iterations to obtain the best solution, with a RMSPE of 0.168 for volume and a RMSPE of 0.179 for speed. The successful application of the proposed methodology framework to real road networks demonstrates its ability to provide results both with satisfactory accuracy and within a reasonable time, thus establishing its potential usefulness to support dynamic traffic assignment modeling, ITS systems, and other strategies.

Over the past few years, the Utah Department of Transportation (UDOT) has developed a system called the Signal Performance Metrics System (SPMS) to evaluate the performance of signalized intersections. This system currently provides data summaries for several performance measures including: 1) Purdue Coordination Diagram, 2) Speed, 3) Approach Volume, 4) Purdue Phase Termination Charts, 5) Split Monitor, 6) Turning Movement Volume Counts, 7) Arrivals on Red, and 8) Approach Delay. There is a need to know the accuracy of the data that are being collected by the Wavetronix SmartSensor Matrix and displayed in the SPMS. The TAC members determined that the following factors would affect the accuracy of radar-based traffic sensors the most: sensor position, number of approach lanes, and volume level. The speed limit factor was added to the study after most of the data collection was completed. The purpose of this research was to collect data at various intersections to determine the accuracy of the data collected by the Wavetronix SmartSensor Matrix.A Mixed Model Analysis of Variance (ANOVA) was employed to analyze the effects that each factor had on the accuracy of the traffic volume count. A total of 14 tests were performed to examine the effects of the factors on traffic volume count accuracy. The sensor position factor was not found to be a statistically significant factor affecting the accuracy of traffic volume counts. The effect of speed limit on traffic volume count accuracy was determined to be inconclusive due to the lack of samples to be tested. The remaining two factors, volume level and number of approach lanes, were found to have a statistically significant effect on the accuracy of traffic volume counts. Based on these two factors, a matrix was created to meet the needs of UDOT to present accuracy values on the SPMS website. This matrix includes the mean, 95 percent confidence interval of the mean, standard deviation, number of samples, and the minimum number of samples needed.

[ES] En la actualidad, uno de los principales desafíos a los que se enfrentan las grandes áreas metropolitanas es la congestión provocada por el tráfico, la cual se ha convertido en un problema importante al que se enfrentan las autoridades de cada ciudad. Para abordar este problema es necesario implementar una solución eficiente para controlar el tráfico que genere beneficios para los ciudadanos, como reducir los tiempos de viaje de los vehículos y, en consecuencia, el consumo de combustible, el ruido, y la contaminación ambiental. De hecho, al analizar adecuadamente la demanda de tráfico, es posible predecir las condiciones futuras del tráfico, y utilizar esa información para la optimización de las rutas tomadas por los vehículos. Este enfoque puede ser especialmente efectivo si se aplica en el contexto de los vehículos autónomos, que tienen un comportamiento más predecible, lo cual permite a los administradores de la ciudad mitigar los efectos de la congestión, como es la contaminación, al mejorar el flujo de tráfico de manera totalmente centralizada. La validación de este enfoque generalmente requiere el uso de simulaciones que deberían ser lo más realistas posible. Sin embargo, lograr altos grados de realismo puede ser complejo cuando los patrones de tráfico reales, definidos a través de una matriz de Origen/Destino (O-D) para los vehículos en una ciudad, son desconocidos, como ocurre la mayoría de las veces. Por lo tanto, la primera contribución de esta tesis es desarrollar una heurística iterativa para mejorar el modelado de la congestión de tráfico; a partir de las mediciones de bucle de inducción reales hechas por el Ayuntamiento de Valencia (España), pudimos generar una matriz O-D para la simulación de tráfico que se asemeja a la distribución de tráfico real. Si fuera posible caracterizar el estado del tráfico prediciendo las condiciones futuras del tráfico para optimizar la ruta de los vehículos automatizados, y si se pudieran tomar estas medidas para mitigar de manera preventiva los efectos de la congestión con sus problemas relacionados, se podría mejorar el flujo de tráfico en general. Por lo tanto, la segunda contribución de esta tesis es desarrollar una Ecuación de Predicción de Tráfico para caracterizar el comportamiento en las diferentes calles de la ciudad en términos de tiempo de viaje con respecto al volumen de tráfico, y aplicar una regresión logística a esos datos para predecir las condiciones futuras del tráfico. La tercera y última contribución de esta tesis apunta directamente al nuevo paradigma de gestión de tráfico previsto, tratándose de un servidor de rutas capaz de manejar todo el tráfico en una ciudad, y equilibrar los flujos de tráfico teniendo en cuenta las condiciones de congestión del tráfico presentes y futuras. Por lo tanto, realizamos un estudio de simulación con datos reales de congestión de tráfico en la ciudad de Valencia (España), para demostrar cómo se puede mejorar el flujo de tráfico en un día típico mediante la solución propuesta. Los resultados experimentales muestran que nuestra solución, combinada con una actualización frecuente de las condiciones del tráfico en el servidor de rutas, es capaz de lograr mejoras sustanciales en términos de velocidad promedio y tiempo de trayecto, ambos indicadores de un menor grado de congestión y de una mejor fluidez del tráfico.
[CA] En l'actualitat, un dels principals desafiaments als quals s'enfronten les grans àrees metropolitanes és la congestió provocada pel trànsit, que s'ha convertit en un problema important al qual s'enfronten les autoritats de cada ciutat. Per a abordar aquest problema és necessari implementar una solució eficient per a controlar el trànsit que genere beneficis per als ciutadans, com reduir els temps de viatge dels vehicles i, en conseqüència, el consum de combustible, el soroll, i la contaminació ambiental. De fet, en analitzar adequadament la demanda de trànsit, és possible predir les condicions futures del trànsit, i utilitzar aqueixa informació per a l'optimització de les rutes preses pels vehicles. Aquest enfocament pot ser especialment efectiu si s'aplica en el context dels vehicles autònoms, que tenen un comportament més predictible, i això permet als administradors de la ciutat mitigar els efectes de la congestió, com és la contaminació, en millorar el flux de trànsit de manera totalment centralitzada. La validació d'aquest enfocament generalment requereix l'ús de simulacions que haurien de ser el més realistes possible. No obstant això, aconseguir alts graus de realisme pot ser complex quan els patrons de trànsit reals, definits a través d'una matriu d'Origen/Destinació (O-D) per als vehicles en una ciutat, són desconeguts, com ocorre la majoria de les vegades. Per tant, la primera contribució d'aquesta tesi és desenvolupar una heurística iterativa per a millorar el modelatge de la congestió de trànsit; a partir dels mesuraments de bucle d'inducció reals fetes per l'Ajuntament de València (Espanya), vam poder generar una matriu O-D per a la simulació de trànsit que s'assembla a la distribució de trànsit real. Si fóra possible caracteritzar l'estat del trànsit predient les condicions futures del trànsit per a optimitzar la ruta dels vehicles automatitzats, i si es pogueren prendre aquestes mesures per a mitigar de manera preventiva els efectes de la congestió amb els seus problemes relacionats, es podria millorar el flux de trànsit en general. Per tant, la segona contribució d'aquesta tesi és desenvolupar una Equació de Predicció de Trànsit per a caracteritzar el comportament en els diferents carrers de la ciutat en termes de temps de viatge respecte al volum de trànsit, i aplicar una regressió logística a aqueixes dades per a predir les condicions futures del trànsit. La tercera i última contribució d'aquesta tesi apunta directament al nou paradigma de gestió de trànsit previst. Es tracta d'un servidor de rutes capaç de manejar tot el trànsit en una ciutat, i equilibrar els fluxos de trànsit tenint en compte les condicions de congestió del trànsit presents i futures. Per tant, realitzem un estudi de simulació amb dades reals de congestió de trànsit a la ciutat de València (Espanya), per a demostrar com es pot millorar el flux de trànsit en un dia típic mitjançant la solució proposada. Els resultats experimentals mostren que la nostra solució, combinada amb una actualització freqüent de les condicions del trànsit en el servidor de rutes, és capaç d'aconseguir millores substancials en termes de velocitat faig una mitjana i de temps de trajecte, tots dos indicadors d'un grau menor de congestió i d'una fluïdesa millor del trànsit.
[EN] Currently, one of the main challenges that large metropolitan areas have to face is traffic congestion, which has become an important problem faced by city authorities. To address this problem, it becomes necessary to implement an efficient solution to control traffic that generates benefits for citizens, such as reducing vehicle journey times and, consequently, use of fuel, noise and environmental pollution. In fact, by properly analyzing traffic demand, it becomes possible to predict future traffic conditions, and to use that information for the optimization of the routes taken by vehicles. Such an approach becomes especially effective if applied in the context of autonomous vehicles, which have a more predictable behavior, thus enabling city management entities to mitigate the effects of traffic congestion and pollution by improving the traffic flow in a city in a fully centralized manner. Validating this approach typically requires the use of simulations, which should be as realistic as possible. However, achieving high degrees of realism can be complex when the actual traffic patterns, defined through an Origin/Destination (O-D) matrix for the vehicles in a city, are unknown, as occurs most of the times. Thus, the first contribution of this thesis is to develop an iterative heuristic for improving traffic congestion modeling; starting from real induction loop measurements made available by the City Hall of Valencia, Spain, we were able to generate an O-D matrix for traffic simulation that resembles the real traffic distribution. If it were possible to characterize the state of traffic by predicting future traffic conditions for optimizing the route of automated vehicles, and if these measures could be taken to preventively mitigate the effects of congestion with its related problems, the overall traffic flow could be improved. Thereby, the second contribution of this thesis was to develop a Traffic Prediction Equation to characterize the different streets of a city in terms of travel time with respect to the vehicle load, and applying logistic regression to those data to predict future traffic conditions. The third and last contribution of this thesis towards our envisioned traffic management paradigm was a route server capable of handling all the traffic in a city, and balancing traffic flows by accounting for present and future traffic congestion conditions. Thus, we perform a simulation study using real data of traffic congestion in the city of Valencia, Spain, to demonstrate how the traffic flow in a typical day can be improved using our proposed solution. Experimental results show that our proposed solution, combined with frequent updating of traffic conditions on the route server, is able to achieve substantial improvements in terms of average travel speeds and travel times, both indicators of lower degrees of congestion and improved traffic fluidity.
Finally, I want to thank the Ecuatorian Republic through the "Secretaría de Educación Superior, Ciencia, Tecnología e Innovación" (SENESCYT), for granting me the scholarship to finance my studies.
Zambrano Martínez, JL. (2019). Efficient Traffic Management in Urban Environments [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/129865
TESIS

The principle of load balancing is to distribute the data load more evenly over the network in order to increase the network performance and efficiency. With dynamic load balancing the routing is undated at certain intervals. This thesis was developed to evaluate load balancing methods in the IP-network of TeliaSonera.Load balancing using short path routing, bottleneck load balancing and load balancing using MPLS have been evaluated. Short path routing is a flow sharing technique that allows routing on paths other than the shortest one.

Load balancing using short path routing is achieved by dynamic updates of the link weights. Bottleneck is in its nature a dynamic load balancing algorithm. Unlike load balancing using short path routing it updates the flow sharing, not the metrics. The algorithm uses information about current flow sharing and link loads to detect bottlenecks within the network. The information is used to calculate new flow sharing parameters. When using MPLS, one or more complete routing paths (LSPs) are defined at each edge LSR before sending any traffic. MPLS brings the ability to perform flow sharing by defining the paths to be used and how the outgoing data load is to be shared among these.

The model has been built from data about the network supplied by TeliaSonera. The model consists of a topology part, a traffic part, a routing part and cost part. The traffic model consists of a OD demand matrix. The OD demand matrix has been estimated from collected link loads. This was done with estimation models; the gravity model and an optimisation model.

The algorithms have been analysed at several scenarios; normal network, core node failure, core link failure and DWDM system failure. A cost function, where the cost increases as the link load increases has been used to evaluate the algorithms. The signalling requirements for implementation of the load balancing algorithm have also been investigated.

This diploma thesis deals with a proposal and a comparison of several options of transportation planning in the shopping area in the urban area of the town of Modřice, which is enlarging due to the building-up of new commercial centres. The first part of the thesis consists of a treatise on the field of traffic engineering, road-traffic telematics and ITS. The core of the work is formed by a detailed analysis of the current state and calibration of the transport simulation system AIMSUN. The following part shows three different ways of transportation in the given area and all of them include a model of the particular area made in the program AIMSUN and an elaborate analysis of the proposed solution. In the last part of the work all the proposed solutions are compared according to the results gained from the AIMSUN model.

L’estimation des matrices origine-destination (OD) est un sujet de recherche important depuis les années 1950. En effet, ces tableaux à deux entrées recensent la demande de transport d'une zone géographique donnée et sont de ce fait un élément clé de l'ingénierie du trafic. Historiquement, les seules données disponibles pour leur estimation par les statistiques étaient les comptages de véhicules par les boucles magnétiques. Ce travail s'inscrit alors dans le contexte de l'installation à Brisbane de plus de 600 détecteurs Bluetooth qui ont la capacité de détecter et d'identifier les appareils électroniques équipés de cette technologie.Dans un premier temps, il explore la possibilité offerte par ces détecteurs pour les applications en ingénierie du transport en caractérisant ces données et leurs bruits. Ce projet aboutit, à l'issue de cette étude, à une méthode de reconstruction des trajectoires des véhicules équipés du Bluetooth à partir de ces seules données. Dans un second temps, en partant de l'hypothèse que l'accès à des échantillons importants de trajectoires va se démocratiser, cette thèse propose d'étendre la notion de matrice OD à celle de matrice OD par lien afin de combiner la description de la demande avec celle de l'utilisation du réseau. Reposant sur les derniers outils méthodologies développés en optimisation convexe, nous proposons une méthode d'estimation de ces matrices à partir des trajectoires inférées par Bluetooth et des comptages routiers.A partir de peu d'hypothèses, il est possible d'inférer ces nouvelles matrices pour l'ensemble des utilisateurs d'un réseau routier (indépendamment de leur équipement en nouvelles technologies). Ce travail se distingue ainsi des méthodes traditionnelles d'estimation qui reposaient sur des étapes successives et indépendantes d'inférence et de modélisation
Origin Destination matrix estimation is a critical problem of the Transportation field since the fifties. OD matrix is a two-entry table taking census of the zone-to-zone traffic of a geographic area. This traffic description tools is therefore paramount for traffic engineering applications. Traditionally, the OD matrix estimation has solely been based on traffic counts collected by networks of magnetic loops. This thesis takes place in a context with over 600 Bluetooth detectors installed in the City of Brisbane. These detectors permit in-car Bluetooth device detection and thus vehicle identification.This manuscript explores first, the potentialities of Bluetooth detectors for Transport Engineering applications by characterising the data, their noises and biases. This leads to propose a new methodology for Bluetooth equipped vehicle trajectory reconstruction. In a second step, based on the idea that probe trajectories will become more and more available by means of new technologies, this thesis proposes to extend the concept of OD matrix to the one of link dependent origin destination matrix that describes simultaneously both the traffic demand and the usage of the network. The problem of LOD matrix estimation is formulated as a minimisation problem based on probe trajectories and traffic counts and is then solved thanks to the latest advances in nonsmooth convex optimisation.This thesis demonstrates that, with few hypothesis, it is possible to retrieve the LOD matrix for the whole set of users in a road network. It is thus different from traditional OD matrix estimation approaches that relied on successive steps of modelling and of statistical inferences

La forte variabilité des trafics est devenue l'un des problèmes majeurs auxquels doivent faire face les gestionnaires d'infrastructures réseau. Dans ces conditions, l'optimisation du routage des flux en se basant uniquement sur une matrice de trafic moyenne estimée en heure de pointe n'est plus pertinente. Les travaux conduits dans cette thèse visent la conception de méthodes d'optimisation dynamiques du routage, adaptant en temps réel les routes utilisées par les flux aux conditions de trafic dans le réseau.Nous étudions tout d'abord le problème d'optimisation des poids OSPF pour le routage intra-domaine dans les réseaux IP, où le trafic est routé le long de plus courts chemins, en fonction des poids des liens. Nous proposons une approche en ligne permettant de reconfigurer dynamiquement les poids OSPF, et donc les routes utilisées, pour répondre aux variations observées du trafic et réduire ainsi le taux de congestion du réseau. L'approche proposée repose sur l'estimation robuste des demandes en trafic des flux à partir de mesures SNMP sur la charge des liens. Les résultats expérimentaux, aussi bien sur des trafics simulés que réels, montrent que le taux de congestion du réseau peut être significativement réduit par rapport à une configuration statique.Dans la même optique, nous nous intéressons également à l'optimisation des réseaux MPLS, qui permettent de gérer l'utilisation des ressources disponibles en affectant un chemin spécifique à chaque LSP. Nous proposons un algorithme inspiré de la théorie des jeux pour déterminer le placement des LSP optimisant un critère de performance non linéaire. Nous établissons la convergence de cet algorithme et obtenons des bornes sur son facteur d'approximation pour plusieurs fonctions de coût. L'intérêt principal de cette technique étant d'offrir des solutions de bonne qualité en des temps de calcul extrêmement réduits, nous étudions son utilisation pour la reconfiguration dynamique du placement des LSP.La dernière partie de cette thèse est consacrée à la conception et au développement d'une solution logicielle permettant le déploiement d'un réseau overlay auto-guérissant et auto-optimisant entre différentes plateformes de cloud computing. La solution est conçue pour ne nécessiter aucun changement des applications. En mesurant régulièrement la qualité des liens Internet entre les centres de données, elle permet de détecter rapidement la panne d'une route IP et de basculer le trafic sur un chemin de secours. Elle permet également de découvrir dynamiquement les chemins dans le réseau overlay qui optimisent une métrique de routage spécifique à l'application. Nous décrivons l'architecture et l'implémentation du système, ainsi que les expériences réalisées à la fois en émulation et sur une plateforme réelle composée de plusieurs centres de données situés dans différents pays
The high variability of traffic has become one of the major problems faced by network infrastructure managers . Under these conditions, flow route optimization based solely on an average busy hour traffic matrix is no longer relevant. The work done in this thesis aims to design dynamic routing optimization methods, adapting in real time the routes used by the flows to the actual network traffic conditions.We first study the problem of OSPF weight optimization for intra-domain routing in IP networks, where the traffic is routed along shortest paths, according to links weights. We propose an online scheme to dynamically reconfigure the OSPF weights and therefore the routes used, to respond to observed traffic variations and reduce the network congestion rate. The proposed approach is based on robust estimation of flow traffic demands from SNMP measurements on links loads. Experimental results, both on simulated and real traffic data show that the network congestion rate can be significantly reduced in comparison to a static weight configuration.On the same idea, we are also interested in optimizing MPLS networks that manage the available resource utilization by assigning a specific path for each LSP. We propose an algorithm inspired by game theory to determine the LSP placement optimizing a nonlinear performance criterion. We establish the convergence of the algorithm and obtain bounds on its approximation factor for several cost functions. As the main advantage of this technique is to offer good quality solutions in extremely reduced computation times, we are studying its use for dynamic reconfiguration of the LSP placement.The last part of this thesis is devoted to the design and development of a software solution for the deployment of a self-healing and self-optimizing network overlay between different cloud platforms. The solution is designed such that no change is required for client applications. By regularly measuring the quality of Internet links between data centers, it can quickly detect an IP route failure and switch the traffic to a backup path. It also allows to dynamically discover the paths in the overlay network that optimize a routing metric specific to the application. We describe the system architecture and implementation, as well as the experiments in both emulation and real platform composed of several data centers located in different countries

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Most of the medium and large cities in the world suffer from the problems related to the growth of the number of vehicles. Congestion, air pollution and weather are some examples of these problems, today constantly reminded of the great damage done to citizens. The use of Information Visualization techniques can serve to support the analysis of these problems and help identify viable and effective solutions for them. On the other hand, the application of Information Visualization to the problems of urban traffic is still a poorly explored area and generally focused on simple aspects of traffic. The present thesis thus addresses the lack of studies in this area, especially in the representation of data related to origin-destination (OD) matrices. In order to do so, a specific classification is proposed for visualizations aimed at the urban traffic scenario, with the purpose of facilitating the identification of works and authors related to the area. In addition, there is the creation of new visualizations, directed to OD arrays, in order to offer different alternatives in the representation of traffic data. Finally, an approach is proposed to evaluate visualizations of OD matrices and correlated information, with the intention of offering adequate feedback to interface designers and enabling the creation of more effective visualizations.
A maioria das cidades de médio e grande porte no mundo sofre dos problemas relacionados ao crescimento do número de veículos. Congestionamentos, poluição do ar e desperdício de tempo são alguns exemplos desses problemas, hoje constantemente lembrados frente aos grandes prejuízos causados aos cidadãos. A utilização de técnicas de Visualização de Informações pode servir para apoiar a análise desses problemas e ajudar a identificar soluções viáveis e efetivas para os mesmos. Por outro lado, a aplicação de Visualização de Informações aos problemas de tráfego urbano ainda é uma área pouco explorada e geralmente focada em aspectos simples do trânsito. A presente tese vem, assim, suprir a carência por estudos nessa área, em especial na representação de dados relacionados a matrizes Origem-Destino (OD). Para tanto, propõe-se uma classificação específica para visualizações voltadas ao cenário do tráfego urbano, com o objetivo de facilitar a identificação de trabalhos e autores relacionados à área. Além disso, há a criação de novas visualizações, voltadas para matrizes ODs, com o intuito de oferecer diferentes alternativas na representação de dados do trânsito. Por fim, propõe-se uma abordagem para avaliar visualizações de matrizes OD e informações correlacionadas, com o intuito de oferecer um feedback adequado aos designers de interface e possibilitar a criação de visualizações mais efetivas.

Esta pesquisa apresenta uma proposta de reconstrução de matriz OD a partir de dados de velocidade da corrente de tráfego disponíveis na web. Para tal, foram estabelecidos três objetivos específicos, os quais incluem: obtenção e avaliação dos dados de velocidade de tráfego; construção de um modelo computacional e aplicação desse em uma rede real. A avaliação dos dados foi realizada por meio da comparação dos valores de velocidade média da corrente de tráfego obtidos da web com os valores aferidos por sensores do tipo laço indutivo. Os resultados indicam que, apesar das velocidades extraídas da web apresentarem maior variância e valores mais baixos, a maior parcela dos dados obteve diferença similar ou inferior a 11%. Na construção da rotina computacional foi utilizado o Método das Médias Sucessivas (MEMS) e na sua avaliação foram realizados testes comparativos cujas referências foram os resultados alcançados pelo autor do método utilizado. A rotina desenvolvida apresentou melhor resultado com relação ao número total de viagens da matriz reconstruída, além de exigir menor número de iterações. Por outro lado, com relação às viagens atribuídas a cada par OD seu desempenho foi inferior. Para avaliar a aderência a realidade o método proposto foi aplicado a uma rede real composta por trechos específicos das rodovias Presidente Dutra, Pedro I, Ayrton Senna e Governador Carvalho Pinto. Devido ao fato da entrada principal do MEMS ser o volume de veículos, foi necessário estimar o mesmo a partir da velocidade fornecida pela API. A matriz reconstruída apresentou forte dependência da capacidade atribuída às vias, evidenciando a necessidade de definir de forma mais cuidadosa esse parâmetro. Embora, ainda seja necessário aprimorar o método proposto e a rotina computacional elaborada, bem como, aprofundar os estudos da fonte de dados utilizada, o experimento de caráter exploratório mostra a possibilidade de reconstruir uma matriz OD a partir de dados disponíveis na web.
This research presents a proposal for the reconstruction of OD matrix from traffic stream velocity data available on the web. To this end, three specific objectives have been established, which include: obtaining and evaluating traffic speed data; construction of a computational model and application of this in a real network. The data were evaluated by the comparison of the mean values of the traffic current, obtained from the web, with those measured by loop sensors. The results indicate that, although the velocities extracted from the web presented higher variance and lower values, the greater part of the data obtained a difference similar to or lower than 11%. In the construction of the computational routine was used the Method of Successive Averages (MEMS) and in its evaluation were performed comparative tests whose references were the results achieved by the author of the used method. The developed routine presented better results in relation to the total number of trips of the reconstructed OD matrix, besides requiring a smaller number of iterations. On the other hand, in relation to the trips attributed to each OD pair the performance was lower. To evaluate the adherence to reality, the proposed method was applied to a real network composed of specific sections of the Presidente Dutra, Pedro I, Ayrton Senna and Governador Carvalho Pinto highways. Due to the fact that the main input of the MEMS is the vehicles flow, was necessary to estimate it from the speed provided by the API. The reconstructed matrix presented a strong dependence on the capacity attributed to the roads, evidencing the need to define this parameter more carefully. Although it is still necessary to improve the proposed method and the elaborated computational routine, as well as to deepen the studies of the used data source, the exploratory experiment shows the possibility of reconstructing an OD matrix from data available on the web.

Les prévisions relatives trafic de données au sein des systèmes de communications sans-fil suggèrent une croissance exponentielle, principalement alimentée par l’essor de transferts vidéo mobiles. Etant donné la nature soudaine et fluctuante des demandes de transfert vidéo, il faut dès à présent réfléchir à de nouveaux algorithmes d’allocation de ressources performants. En effet, les algorithmes en couche physique traditionnels, qui réalisent de l’allocation de ressources sous l’hypothèse classique que les transmetteurs sont toujours saturés avec des bits d’information, risquent à l’avenir de s’avérer inefficients. Pour cette raison, les algorithmes de demain se doivent d’être dynamiques, dans le sens où ils seront capables de prendre en compte la nature stochastique des fluctuations du trafic de données et qu’ils intégreront des informations issus de processus de couches supérieures.L’idée centrale de cette thèse est de développer des algorithmes, travaillant avec des informations issues de la couche PHY et de la couche NET, dans un scénario Multi-cells et MIMO (Multiple Inputs, Multiple Outputs).Plus particulièrement, nous considérons un réseau de stations de base (BS) équipés avec plusieurs antennes, chargés de servir plusieurs terminaux mobiles équipés d’une seule antenne (UT) dans leurs cellules respectives. Ce qui nous différencie des travaux précédents, c’est que nous tenons compte de l’aléa avec lequel des demandes de transferts peuvent arriver et que, pour cette raison, nous modélisons la formation de queue de données au niveau des stations de base. Dans cette disposition, nous développons plusieurs algorithmes multicouches, réalisant de l’allocation de ressources décentralisée, et ce, dans une optique d’efficacité énergétique. En particulier, il s’agit ici de réaliser des algorithmes réalisant du beamforming de façon décentralisée et capables de contrôler des fluctuations de trafic, des algorithmes optimisant l’efficacité énergétique sous une contrainte de qualité de service moyenne, des algorithmes de planification décentralisés dans des scénarios multi-cellulaires. Dans cette perspective, nous choisissons de recourir non seulement à des outils d’optimisation de la théorie de Lyapunov, mais également à la théorie des matrices aléatoires et à la théorie du contrôle stochastique
Future wireless communication systems are expected to see an explosion in the wireless traffic which is mainly fueled by mobile video traffic. Due to the time varying and bursty nature of video traffic, wireless systems will see a widerrange of fluctuations in their traffic patterns. Therefore, traditional physical layer based algorithms which perform resource allocation under the assumption that the transmitters are always saturated with information bits, might no longer be efficient. It is, thus, important to design dynamic resource allocation algorithms which can incorporate higher layer processes and account for the stochastic nature of the wireless traffic.The central idea of this thesis is to develop cross-layer design algorithmsbetween the physical and the network layer in a multiple input multiple output (MIMO) multi-cell setup. Specifically, we consider base stations (BSs) equipped with multiple antennas serving multiple single antenna user terminals (UTs) in their respective cells. In contrast to the previous works, we consider the randomness in the arrival of information bits and hence account for the queuing at the BSs. With this setup, we develop various cross-layer based resource allocation algorithms. We incorporate two important design considerations namely decentralized design and energy efficiency. In particular, we focus on developing decentralized beamforming and traffic flow controller design, energy efficient design under time average QoS constraints and decentralized scheduling strategy in a multi-cell scenario. To this end, we use tools from Lyapunov optimization, random matrix theory and stochastic control theory

Neste trabalho é proposto um método de carregamento incremental dos fluxos veiculares para a estimação de matriz O-D sintética. A principal motivação para o desenvolvimento deste trabalho está na complexidade dos métodos de estimação de matriz sintética pelo método iterativo, que tem conduzido a resultados não satisfatórios. O método de carregamento incremental, ora proposto neste trabalho, pode ser definido como o inverso do método de alocação incremental de viagens aos arcos de uma rede viária. A matriz O-D obtida com este método é o resultado da soma sucessiva das sub-matrizes estimadas através das parcelas dos fluxos observados nos arcos da rede. Este método pode ser aplicado em qualquer tipo de rede viária: congestionada ou não congestionada e com ou sem continuidade de fluxo. Para verificação do desempenho do método foram realizados testes experimentais, nos quais os resultados obtidos foram comparados com os valores observados. O desempenho do método incremental não se mostrou satisfatório. Assim, com o intuito de verificar a sua utilidade como um método alternativo os mesmos dados foram processados através de dois métodos iterativos. Os resultados mostraram que os erros são ainda maiores do que os obtidos pelo método proposto. A principal conclusão deste trabalho é que o método incremental pode ser usado como uma alternativa aos métodos iterativos.
A synthetic O-D matrix estimation method, based on incremental loading of traffic flow, was proposed in this work. This research was motivated because of the complexity of the iterative methods for synthetic matrix estimation that might produce bias accumulation in the results. The referred incremental loading method could be defined as the inverse of the incremental assignment method for trips to links of a traffic network. The O-D matrix is gathered by successively summing the sub-matrices obtained from parts of the traffic flow counted on the links of the traffic network. This method could be applied to any traffic networks: congested or uncongested and with or without volumetric continuity. As a part of verification proceeding, several experimental tests were carried out to evaluate the method performance. In these tests the estimated results were compared with the real values. These results show that the incremental loading method performance was not satisfactory. Thus, aiming to test the utility of the incremental method, a second round of experimental tests was conducted to evaluate two iterative methods. In these second round tests, the results show that theses methods performance was worse those of the incremental method. The main conclusion of this work is that the incremental loading method for synthetic matrices estimation could be used as an alternative to the iterative methods.

La ré-identification de véhicules permet d’estimer deux paramètres clés en gestion dynamique de trafic : les temps de parcours et les matrices origine-destination. Dans cette thèse, nous avons choisi d'effectuer cette ré-identification par analyse des signatures magnétiques mesurées par des capteurs tri-axiaux placés sur la chaussée. La signature magnétique est générée par l'aimantation du véhicule : elle est alors susceptible de varier en fonction de l'orientation du véhicule par rapport au champ magnétique terrestre (à cause de l'aimantation induite dans le plan horizontal), et en fonction de sa position latérale relative par rapport aux capteurs. Les expérimentations que nous avons menées nous ont permis d'obtenir une base de données de signatures magnétiques, et ainsi d'évaluer les performances des deux méthodes de ré-identification que nous avons élaborées.La première méthode consiste à comparer directement des paires de signatures magnétiques mesurées par les capteurs. Les calculs de distances entre les paires sont effectués avec des algorithmes classiques comme la distance euclidienne. Les résultats obtenus sont très bons, et baissent peu lorsque le véhicule change d'orientation. Toutefois, ils sont très sensibles à la déformation des signaux due au décalage latéral du véhicule, et nécessitent donc de positionner un capteur tous les 0.20m sur toute la largeur de la voie.Dans un second temps, nous proposons une méthode de ré-identification qui compare des paires de modèles magnétiques de véhicules. Ces modèles sont composés de plusieurs dipôles, et sont calculés à partir des signatures mesurées. La modélisation a pour but de s’affranchir du décalage latéral du véhicule, en remontant à la position relative du véhicule par rapport aux capteurs. Avec deux fois moins de capteurs que la méthode précédente, les résultats obtenus sur signaux réels sont également très bons, même s'ils sont un peu plus sensibles au changement d'orientation du véhicule. De plus, une simulation nous permet d'extrapoler qu'il est effectivement possible de s'affranchir du décalage latéral avec cette méthode
Vehicle re-identification gives access to two essential data for dynamic traffic management: travel times and origin-destination matrices. In this thesis, we chose to re-identify vehicles by analysing their magnetic signatures measured with several 3-axis magnetic sensors located on the road. A magnetic signature is created by the vehicle magnetization. Therefore, the vehicle orientation to the Earth’s magnetic field (which determines the induced magnetization) and the variation of the lateral position of the vehicle relative to the sensors’ one might both have an impact on the magnetic signature. We gathered our experiments’ results into a database of magnetic signatures that we used to evaluate the performances of the two vehicle re-identification methods we developed.The first method is a direct comparison of pairs of magnetic signatures measured by the sensors. Distances between pairs of signatures are computed using classic algorithms such as the Euclidean distance. This method’s results are very positive and the vehicle change of orientation has only a slight impact on them. However, the distortion of signals due to a lateral offset in the vehicle position has a strong impact on the results. As a consequence, sensors have to be placed every 0.20m over the road’s entire width.The second proposed method compares pairs of vehicles’ magnetic models. Those models are composed of several magnetic dipoles and are determined from the measured signatures. Magnetic modelling aims to suppress the influence of the vehicle lateral position on the results by assessing the relative position of the vehicle above the sensors. Although the vehicle orientation has slightly more impact on the performances than with the first method, the overall results are more promising. This method also allows us to divide by two the number of sensors used

Il Teorema di Perron-Frobenius deve il suo nome ai matematici tedeschi Oskar Perron (1880 - 1975) e Ferdinand Georg Frobenius (1849 - 1917). Fu Perron che per primo si dedicò allo studio di matrici quadrate a entrate positive, e pubblicò nel 1907 il "Teorema di Perron", in cui si dimostra che tali matrici hanno un unico autovalore positivo di modulo massimo, chiamato radice di Perron, e tutti gli altri autovalori diversi da lui hanno modulo minore. L'autovettore associato alla radice di Perron ha componenti tutte positive e ogni altro autovettore a componenti non negative della matrice considerata è un suo multiplo positivo. Frobenius nel 1912 estese questi risultati a matrici quadrate a entrate non negative "Teorema di Perron-Frobenius". Benchè poco conosciuto, questo teorema ha molte applicazioni, per esempio nell'algoritmo di PageRank utilizzato da Google per la ricerca delle pagine, o nel modello di Leslie per prevedere la crescita di una popolazione, etc... Noi faremo vedere come si applica la teoria di Perron-Frobenius allo studio dei sistemi dinamici, indagando lo sviluppo del traffico all'interno di una rete stradale con numero di macchine costante.

Des réseaux de capteurs acoustiques sont actuellement mis en place dans plusieurs grandes villes afin d’obtenir une description plus fine de l’environnement sonore urbain. Un des défis à relever est celui de réussir,à partir d’enregistrements sonores, à estimer des indicateurs utiles tels que le niveau sonore du trafic routier. Cette tâche n’est en rien triviale en raison de la multitude de sources sonores qui composent cet environnement. Pour cela, la Factorisation en Matrices Non-négatives (NMF) est considérée et appliquée sur deux corpus de mixtures sonores urbaines simulés. L’intérêt de simuler de tels mélanges est la possibilité de connaitre toutes les caractéristiques de chaque classe de son dont le niveau sonore exact du trafic routier. Le premier corpus consiste en 750 scènes de 30 secondes mélangeant une composante de trafic routier dont le niveau sonore est calibré et une classe de son plus générique. Les différents résultats ont notamment permis de proposer une nouvelle approche, appelée « NMF initialisée seuillée », qui se révèle être la plus performante. Le deuxième corpus créé permet de simuler des mixtures sonores plus représentatives des enregistrements effectués en villes, dont leur réalisme a été validé par un test perceptif. Avec une erreur moyenne d’estimation du niveau sonore inférieure à 1,2 dB, la NMF initialisée seuillée se révèle, là encore, la méthode la plus adaptée aux différents environnements sonores urbains. Ces résultats ouvrent alors la voie vers l’utilisation de cette méthode à d’autres sources sonores, celles que les voix et les sifflements d’oiseaux, qui pourront mener, à terme, à la réalisation de cartes de bruits multi-sources
Acoustic sensor networks are being set up in several major cities in order to obtain a more detailed description of the urban sound environment. One challenge is to estimate useful indicators such as the road traffic noise level on the basis of sound recordings. This task is by no means trivial because of the multitude of sound sources that composed this environment. For this, Non-negative Matrix Factorization (NMF) is considered and applied on two corpuses of simulated urban sound mixtures. The interest of simulating such mixtures is the possibility of knowing all the characteristics of each sound class including the exact road traffic noise level. The first corpus consists of 750 30-second scenes mixing a road traffic component with a calibrated sound level and a more generic sound class. The various results have notably made it possible to propose a new approach, called ‘Thresholded Initialized NMF', which is proving to be the most effective. The second corpus created makes it possible to simulate sound mixtures more representatives of recordings made in cities whose realism has been validated by a perceptual test. With an average noise level estimation error of less than 1.3 dB, the Thresholded Initialized NMF stays the most suitable method for the different urban noise environments. These results open the way to the use of this method for other sound sources, such as birds' whistling and voices, which can eventually lead to the creation of multi-source noise maps

De l'analyse des méthodes existantes à la recherche d'une méthodologie, du raisonnement au développement, de la réalisation à l'application, nous pouvons conclure qu'une nouvelle méthode (REMODE) a été développée pour reconstituer une matrice origine-destination de trafic interurbain à partir des comptages. Cette méthode, inspirée de la programmation dynamique et des théories des graphes, modélise les comportements des voyageurs d'une part, et tire avantage du calcul mathématique d'autre part. Le but de la fonction objectif est de minimiser la différence entre le comptage et la valeur estimée sur les compteurs. A partir de cela, tous les processus, notamment ceux de génération, distribution et affectation, sont conçus d'une façon continue afin de garantir leur cohérence ainsi que le sens global de chaque élément concerné. Les principales nouveautés de cette méthode sont : (1) Le calibrage autonome du modèle est assuré par le programme lui-même. (2) La simulation de l'écoulement du trafic est fondée sur la désagrégation des voyageurs et l'offre du transport. (3) Les définitions des priorités au calcul ont été également entreprises dans le développement de la fonction objectif. Cette méthode a été calibrée et appliquée au réseau routier français et les données de comptages en 1990. Les principales matrices origine-destination reconstituées (matrices régionale, départementale et intermédiaire) sont interprétables du point de vue mathématique et socio-économique du transport.

Mes travaux de recherche ont pour sujet unificateur : les déplacements et les réseaux de transport ; et ils ont été traités par une approche unique, la modélisation physico-économique à caractère mathématique et algorithmique.
Une telle modélisation comporte quatre aspects : un contenu sémantique, à caractère physique ou économique ; une formulation mathématique ; un solveur technique ; un aspect empirique (métrologie, statistique, économétrie).
Les disciplines mises en œuvre sont variées : théorie des réseaux, optimisation, informatique algorithmique, probabilités et statistiques, et aussi économie, socio-économie et physique du trafic. Mes contributions théoriques concernent la théorie des réseaux, l'économie du transport et la physique du trafic.
Mes travaux se répartissent en quatre thèmes :
A. La mesure et la modélisation du trafic. Au niveau local d'une route, j'ai analysé la relation entre flux et vitesse en mettant en cohérence l'analyse désagrégée, probabiliste au niveau du mobile individuel ; et l'analyse macroscopique en termes de flux et de distribution statistique des temps.
B. La modélisation des réseaux et des cheminements. L'équilibre entre offre de transport et demande de déplacement conjugue une dimension spatiale - topologique, une dimension temporelle, et une dimension comportementale - économique. Les enjeux de modélisation concernent : la représentation de l'offre et la demande ; la formulation et les propriétés d'existence – unicité – stabilité ; les algorithmes. Je me suis intéressé à la diversité des comportements ; et à la modélisation fine de l'offre et à la dimension temporelle.
C. L'analyse socio-économique des déplacements. Je me suis intéressé à l'usage de divers moyens de transport et à la prospection de leur clientèle potentielle ; au choix d'horaire de déplacement ; aux caractéristiques à la fois économiques et dynamiques de la congestion.
D. La distribution spatiale des déplacements et des activités. Je me suis intéressé d'une part à l'observation des flux par relation origine-destination (O-D) et à l'inférence statistique des matrices O-D ; et d'autre part, à la justification microéconomique des déplacements en raison de la localisation et de l'utilité des activités.

Nous abordons le problème de l'optimisation des mesures dans les grands réseaux Internet par la théorie des plans d'expériences optimaux. Cette approche donne lieu d'étudier des problèmes de grande taille en conception optimale d'expériences, pour lesquels nous développons une méthode de résolution fondée sur l' Optimisation Conique du Second Ordre. Le cœur de notre méthode est un théorème de réduction du rang en optimisation semi-définie. Certains aspects combinatoires sont également étudiés. L'application à l'inférence des matrices de trafic dans les réseaux IP fait l'objet de la seconde partie de ce manuscrit. Nous développons une méthode où l'on optimise l'estimation de plusieurs combinaisons linéaires (tirées de façon aléatoire) des demandes de trafic. Nous comparons notre approche aux précédentes au travers de simulations sur des données réelles. En particulier, nous traitons des instances pour lesquelles les approches précédentes étaient incapables de fournir une solution.

Les phosphoinositides jouent un rôle essentiel dans le contrôle spatio-temporel de grandes voies de signalisation impliquées dans la prolifération, la survie, la dynamique du cytosquelette, le trafic ou la migration. Le phosphatidylinositol 5-phosphate (PtdIns5P) est le dernier membre de la famille à avoir été caractérisé et ses fonctions ne sont pas encore totalement connues. Dans ce travail, nous avons étudié le rôle de ce second messager lipidique dans la signalisation en relation avec la survie (régulation de la voie PI3-kinase/Akt) et la migration (activation des GTPases de la famille Rho). Dans un premier modèle, nous avons étudié les processus invasifs des lymphomes anaplasiques à grandes cellules exprimant la protéine chimérique NPM-ALK au fort pouvoir transformant. Nous avons montré que la dissémination de ces lymphomes dépendait de la GTPase Rac1 qui orchestre la structuration d'invadopodes fonctionnels en régulant la formation du complexe CD44/MMP-9/Hsp90 sur la surface des cellules NPM-ALK(+). CD44 ancre le complexe à la surface des cellules et Hsp90 est requise pour l'activation extracellulaire de MMP-9. De façon intéressante, nous avons mesuré des taux élevés de PtdIns5P dans les cellules NPM-ALK(+), qui dans ce modèle est produit par la lipide kinase PIKfyve activée par NPM-ALK. L'inhibition de PIKfyve conduit à un blocage de l'invasion associé à une modification de la répartition de MMP-9 à la surface cellulaire, ainsi qu'à un défaut de sa maturation, suggérant que le PtdIns5P serait central à l'invasion des lymphomes NPM-ALK(+). En parallèle, nous avons étudié le PtdIns5P dans l'infection par la bactérie pathogène Shigella flexneri responsable de la dysenterie chez l'homme. L'équipe avait montré que le facteur de virulence IpgD transformait le PtdIns(4,5)P2 en PtdIns5P, ce qui conduisait à une activation de la voie de survie PI 3-Kinase/Akt. Nous avons montré que le PtdIns5P active le récepteur à l'EGF (EGFR)indépendamment de son ligand, et que ce dernier est requis pour l'activation d'Akt. De plus, le PtdIns5P agit en perturbant le trafic de l'EGFR qui n'est plus dégradé suite à son activation mais plutôt recyclé pour maintenir la cellule activée. Dans ce modèle, le PtdIns5P modulerait les propriétés de diffusion de la membrane plasmique pour conduire à l'activation du récepteur. Par ailleurs, nous avons montré que le PtdIns5P activait les GTPases Rac1 (en liant directement son facteur d'échange Tiam1)et Cdc42 en périphérie cellulaire où cette dernière pourrait jouer un rôle dans la dynamique des membranes requises pour l'activation sans ligand du récepteur. Le module Tiam1/Rac1 répond par ailleurs à des taux élevés de PtdIns5P en activant la dynamique de l'actine de façon polarisée et en se localisant au niveau des endosomes précoces où nous mesurons une accumulation de PtdIns5P, ce qui induit un chimiotactisme fort en réponse à un gradient de sérum. Ces données permettent de proposer un rôle du PtdIns5P dans l'intégration entre le trafic et la dynamique de l'actine pour favoriser les voies de recyclage de récepteurs pour réguler la survie et l'invasion
Phosphoinositides are key regulators of signalling pathway involved in proliferation, survival, cytoskeleton organization, vesicular trafficking and migration. Phosphatidylinositol 5-phosphate (PtdIns5P) is the last characterized and its metabolism and cellular functions are still elusive. In this work, we focused on the potential role of this lipid second messenger in signalling regulating survival (regulation of the PI 3-Kinase pathway) and migration (activation of Rho family GTPases). In a first model, we studied the invasiveness of anaplastic large cell lymphomas (ALCL) expressing the chimeric tyrosine kinase oncogene NPM-ALK, which drives malignant transformation of 75% of ALCLs. We showed that dissemination of these lymphomas is dependent on the GTPase Rac1, which promotes the structuration of functional invadopodia by regulating the formation of the CD44/MMP-9/Hsp90 complex at the surface of NPM-ALK(+) cells. CD44 anchors the complex on the cell surface, and Hsp90 is required for the extracellular activation of MMP-9. Interestingly, we measured elevated levels of PtdIns5P in NPM-ALK(+) cells and its production is dependent on the NPM-ALK-activated PtdIns 5-Kinase, PIKfyve. Inhibition of PIKfyve strongly reduces the invasive capacities by disturbing MMP-9 cell surface distribution, which leads to defects in its activation, suggesting that PtdIns5P plays a central role in the srpeading of NPM-ALK(+) lymphomas. In parallel, we studied the role of PtdIns5P during Shigella flexneri infection, which is responsible for the dysentery in humans. Our group previously showed that the virulence effector IpgD transforms the PtdIns(4,5)P2 into PtdIns5P, and that this conversion drives the activation of the PI 3-Kinase/Akt survival pathway. We found that the EGF receptor is the key intermediate between PtdIns5P and Akt activation. PtdIns5P, that we found accumulated on early endosomes, induces modifications of trafficking, which abolishes EGFR degradation and promotes its recycling towards the plasma membrane. In this model, PtdIns5P modulates the diffusion properties of the plasma membrane to promote receptor activation without ligand. In addition, we showed that PtdIns5P activates the Rac1 GTPases, by binding to the PH domain of its exchange factor Tiam1. Cdc42 also gets activated at the cell periphery where it could be involved in the membrane dynamic required for the activation of receptors without ligands and the subsequent internalization. The Tiam1/Rac1 module responds to elevated levels of PtdIns5P by inducing a strong polarized actin dynamics, leading to chimiotactism in response to serum gradients, and is an important component of anaplastic lymphomas metastatic process. This work points to a crucial role of PtdIns5P in the integration between traffic and actin dynamic to favour the recycling pathway of receptors to regulate the survival and invasion

[ES] Las redes de sensores inalámbricas (WSN) han experimentado un resurgimiento debido al desarrollo de la Internet de las Cosas (IoT). Una de las características de las aplicaciones de la IoT es la necesidad de hacer uso de dispositivos sensores y actuadores. En aplicaciones como automatización de edificios, de gestión energética, industriales o de salud, los nodos sensores que componen la WSN, transmiten información a un colector central o sink. La información es posteriormente procesada, analizada y utilizada para propósitos específicos. En cada una de estas aplicaciones, los dispositivos sensores pueden considerarse como parte de una WSN. En ese sentido el modelado y la evaluación de las prestaciones en las WSN es importante, ya que permite obtener una visión más clara de su comportamiento, facilitando un adecuado diseño y una exitosa puesta en operación. En el presente trabajo de tesis se han desarrollado modelos matemáticos para evaluar las prestaciones de WSN, los cuales están basados en Cadenas de Markov en Tiempo Discreto (DTMC). Los parámetros de prestaciones elegidos para la evaluación son: energía consumida promedio, eficiencia energética, caudal cursado y retardo promedio de los paquetes. Los resultados que se han obtenido han sido validados por medio de simulación basada en eventos discretos (DES). Existen estudios de WSN en escenarios homogéneos, donde los nodos que componen la red inalámbrica son del mismo tipo y tienen las mismas características de operación. En estos análisis se definen WSN homogéneas compuestas por un nodo central o sumidero (sink), que recibe la información de los nodos sensores localizados alrededor, formando una célula o cluster. Estos nodos realizan las transmisiones en SPT (Single Packet Transmission), enviando un solo paquete por ciclo de transmisión. Sin embargo, es posible encontrar, más ahora con el desarrollo de la IoT, escenarios donde coexisten distintos tipos de nodos, con características diferentes y, por tanto, con requerimientos de operación específicos. Esto da lugar a la formación de clusters cuyos nodos tienen aplicaciones distintas, desigual consumo de energía, diversas tasas de trasmisión de datos, e incluso diferentes prioridades de acceso al canal de transmisión. Este tipo de escenarios, que denominamos heterogéneos, forman parte de los escenarios estudiados en el presente trabajo de tesis. En una primera parte, se ha desarrollado un modelo para evaluar las prestaciones de una WSN heterogénea y con prioridades de acceso al medio. El modelado incluye un par de DTMC de dos dimensiones (2D-DTMC) cada una, cuya solución en términos de la distribución de probabilidad estacionaria, es utilizada para determinar los parámetros de prestaciones. Se desarrollan, por tanto, expresiones cerradas para los parámetros de prestaciones, en función de la distribución estacionaria que se ha obtenido a partir de la solución de las 2D-DTMC. En una segunda parte, se desarrolla un modelo analítico también pensado para escenarios heterogéneos y con prioridades, pero en el que los nodos de la WSN, cuando consiguen acceso al canal, transmiten un conjunto de paquetes en vez de uno solo como en el modelo de la primera parte. Estos dos modos de operación de los sensores los denominamos aggregated packet trans- mission (APT) y single packet transmission (SPT), respectivamente. El número de paquetes que un nodo funcionando en APT trasmite cuando accede al canal es el menor entre un parámetro configurable y el número de paquetes que tuviera en la cola en ese momento. Este modo de operación consigue una mayor eficiencia energética y un aumento en el caudal cursado, además de una disminución en el retardo promedio de los paquetes. En una tercera parte, se propone un nuevo procedimiento analítico para la determinación del consumo energético de los nodos que conforman una WSN. A diferencia de los métodos de cálculo anteriores, la nueva prop
[CA] Les xarxes de sensors sense fils (WSN) han experimentat un ressorgiment causa de al desenvolupament de la Internet de les Coses (IoT). Una de les característiques de IoT és la inclusió, en les seves aplicacions, de dispositius sensors i actuadors. En aplicacions com automatització d'edificis, de gestió energètica, industrials o de salut, els nodes sensors que componen la WSN, transmeten informació a un col·lector central o sink. La informació és posteriorment processada, analitzada i utilitzada per a propòsits específics. En cadascuna d'aquestes aplicacions, els dispositius sensors poden considerar com a part d'una WSN. En aquest sentit el modelitzat i l'avaluació de l'acompliment en les WSN és important, ja que permet obtenir una visió més clara del seu comportament, facilitant un adequat disseny i una exitosa posada en operació. En el present treball de tesi s'han desenvolupat models matemàtics per avaluar l'acompliment de WSN, els quals estan basats en Cadenes de Markov en Temps Discret (DTMC). Els paràmetres d'acompliment obtinguts per a l'avaluació són: energia consumida mitjana, eficiència energètica, cabal cursat i retard mitjà dels paquets. Els resultats que s'han obtingut, han estat validats per mitjà de simulació basada en esdeveniments discrets (DES). Existeixen estudis de WSN en escenaris homogenis, on els nodes que componen la xarxa sense fils són de el mateix tipus i tenen les mateixes característiques d'operació. En aquests anàlisis prèvies es defineixen WSN homogènies compostes per un node central o embornal (sink), que rep la informació dels nodes sensors localitzats al voltant, formant una cèl·lula o cluster. Aquests nodes realitzen les transmissió en SPT (Single Packet Transmission), és a dir, enviant un sol paquet cada vegada que transmeten. No obstant això, és possible trobar, més ara amb el desenvolupament de la IOT, escenaris on hi ha una coexistència de distints tipus de nodes, amb característiques diferents i, per tant, amb requeriments d'operació específics. Això dona lloc a formació de clusters els nodes tenen aplicacions diferents, desigual consum d'energia, diverses taxes de transmissió de dades, i fins i tot diferent prioritats d'accés a canal de transmissió. Aquest tipus d'escenaris, que anomenem heterogenis, formen part dels escenaris estudiats en el present treball de tesi. En una primera part, s'ha desenvolupat un model per avaluar l'acompliment d'una WSN heterogènia i amb prioritats d'accés al medi. El modelitzat inclou un parell DTMC de dues dimensions (2D-DTMC), la solució en termes de la distribució estacionària de probabilitat, és utilitzada per obtenir posteriorment els paràmetres d'acompliment. Es desenvolupen, per tant, expressions tancades per a la determinació dels paràmetres d'acompliment, on és substituïda la distribució estacionària que s'ha obtingut a partir de la solució de les 2D-DTMC. En una segona part, es desenvolupa un model, en el qual els nodes pertanyents a la WSN, poden transmetre els seus paquets en agregat (APT) en escenaris heterogenis i amb prioritats. A diferència del model anterior, on els nodes transmeten un paquet per cicle (SPT), en APT els nodes poden transmetre més d'un paquet. Això porta com a conseqüència una major eficiència energètica, a més d'un augment en el cabal cursat i disminució en el retard mitjana. En una tercera part, es proposa un nou desenvolupament analític per a la determinació del consum energètic dels nodes que conformen una WSN. A diferència de les expressions utilitzades anteriorment per al càlcul del consum energètic, aquesta proposta alternativa permet obtenir resultats més precisos a través del desenvolupament d'expressions més intuïtives i sistemàtiques. Amb aquest nou procediment, es realitzen estudis energètics per WSN en escenaris homogenis i heterogenis.
[EN] Wireless sensor networks (WSN) have experienced a resurgence due to the development of the Internet of Things (IoT). One of the characteristics of IoT is the deployment of applications that require sensor devices and actuators. In applications such as building automation, energy management, industrial or health, the sensor nodes that make up the WSN transmit information to a central collector or sink. The information is processed, analyzed, and used for specific purposes. In each of these applications, the sensor devices can be considered part of a WSN. In this sense, the modeling and performance evaluation of WSN is important, since it allows obtaining a clearer vision of their behavior, facilitating an adequate design and a successful operation. In the present thesis, analytical models based on Discrete Time Markov Chains (DTMC) have been developed to evaluate the performance of WSN. The parameters defined for the performance evaluation are: average consumed energy, energy efficiency, throughput and average packet delay. The obtained results have been validated by means of discrete event simulation (DES). There are studies of WSN in homogeneous scenarios, where the nodes that compose the WSN are of the same type and have the same operating characteristics. In these previous studies, homogeneous WSN are defined as a cell or cluster composed of a central node or sink, which receives the information from the sensor nodes located around it. These nodes operate in SPT (Single Packet Transmission), sending a single packet per transmission cycle. However, it is possible to find, especially now with the development of the IoT, scenarios where different types of nodes coexist, although they have different characteristics or specific operational requirements. This results in the formation of clusters whose nodes have different applications, uneven power consumption, different data transmission rates, and even different priorities for access to the transmission channel. These types of scenarios, which we call heterogeneous, are part of the scenarios studied in this thesis work. In the first part, a model has been developed to evaluate the performance of a heterogeneous WSN and with priorities to access a common channel. The model includes a two-dimensional DTMC pair (2D-DTMC), whose solution in terms of the stationary probability distribution is used to obtain the performance parameters. Closed expressions are provided for the determination of performance parameters of interest, given in terms of the stationary distribution of the 2D-DTMC. In a second part, an analytical model is developed to evaluate the performance of a heterogeneous WSN, where nodes operate in aggregate packet transmission (APT) mode and deploy different channel access priorities. Un like the previous model, where the nodes transmit one packet per cycle (SPT) when they gain access to the channel, in APT the nodes can transmit a number of packets larger than one, that is the minimum between a configurable parameter and the number of packets in the packet queue of the node. This results in greater energy efficiency and throughput, while decreases the average packet delay. In a third part, a new analytical model is proposed to determine the energy consumption of the nodes that make up a WSN. Unlike previous computation procedures, this alternative proposal is based on more intuitive and systematic expressions and allows to obtain more accurate results. With this new procedure, energy studies are performed for WSN in homogeneous and heterogeneous scenarios.
Este trabajo se ha desarrollado en el marco de los siguientes proyectos de investigación: Platform of Services for Smart Cities with Dense Machine to Machine Networks, PLASMA, TIN2013-47272-C2-1-R and New Paradigms of Elastic Networks for a World Radically Based on Cloud and Fog Computing, Elastic Networks, TEC2015-71932-REDT. También quisiera agradecer el apoyo recibido por parte de the European Union under the program Erasmus Mundus Partnerships, project EuroinkaNet, GRANT AGREEMENT NUMBER - 2014-0870/001/001 y La Secretaria de Educación Pública (México), bajo el Programa para el Desarrollo Profesional Docente: SEP-SES (DSA/103.5/15/6629).
Portillo Jiménez, C. (2021). Modelado y evaluación de prestaciones de redes de sensores inalámbricos heterogéneos con ciclo de trabajo síncrono [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/171275
TESIS

Today, the main research field for the automotive industry is to find solutions for active safety. In order to perceive the surrounding environment, tracking nearby traffic objects plays an important role. Validation of the tracking performance is often done in staged traffic scenarios, where additional sensors, mounted on the vehicles, are used to obtain their true positions and velocities. The difficulty of evaluating the tracking performance complicates its development. An alternative approach studied in this thesis, is to record sequences and use non-causal algorithms, such as smoothing, instead of filtering to estimate the true target states. With this method, validation data for online, causal, target tracking algorithms can be obtained for all traffic scenarios without the need of extra sensors. We investigate how non-causal algorithms affects the target tracking performance using multiple sensors and dynamic models of different complexity. This is done to evaluate real-time methods against estimates obtained from non-causal filtering. Two different measurement units, a monocular camera and a LIDAR sensor, and two dynamic models are evaluated and compared using both causal and non-causal methods. The system is tested in two single object scenarios where ground truth is available and in three multi object scenarios without ground truth. Results from the two single object scenarios shows that tracking using only a monocular camera performs poorly since it is unable to measure the distance to objects. Here, a complementary LIDAR sensor improves the tracking performance significantly. The dynamic models are shown to have a small impact on the tracking performance, while the non-causal application gives a distinct improvement when tracking objects at large distances. Since the sequence can be reversed, the non-causal estimates are propagated from more certain states when the target is closer to the ego vehicle. For multiple object tracking, we find that correct associations between measurements and tracks are crucial for improving the tracking performance with non-causal algorithms.

碩士
國立交通大學
土木工程研究所
82
Coventional methods for obtaining origin-destina- tion(OD) trip matrix in urban areas are prone to con- siderable sampling error. For these reasons several researchers try to develop methods for estimating OD matrix from traffic count data. The purpose of this thesis lies in proposing a new estimating approach which needsless data. This reseach is divided into two parts. The first part we derived the feasible trip matrix set. Then, we calibrate the parameter of entropy model by means of improving iteratively the parameter to minimize the errors between estimated trip matrix and the feasible trip matrix set. Finally, we estimate trip matrix. The second part we develop a calibrating method which is based on the sensitivity analysis of CDA model. The calibrating method is to minimize the errors between the estimated link flow and the observed link flow by improving iteratively the para- meter. Finally, we estimate trip matrix.

碩士
國立成功大學
交通管理(科學)學系
82
The intercity private O-D matrix is very important but difficultly collected data in Taiwan. To save the cost of collecting above data ， it is possible to use traffic flows on existed freeway to estimate the O-D matrix. Most existing mothods must use the on-off ramps flows to estimate the O-D matrix ， but in Taiwan we just have the observed flows on all of the ten toll stations. So this research will develop a serial estimating methods which use above flows data and a prior O-D matrix to estimate the intercity private O-D matrix in Taiwan.

碩士
國立交通大學
網路工程研究所
104
This thesis presents methods to implementing multi-path routing and measuring network traffic matrix. We used the functions of Group Table defined in OpenFlow specifications; Group tables of type select were used to route traffic with the same destination IP subnet to different ports of a OpenFlow switch. To support multi-path routing, we only need to compare the destination IP addresses. However, to measure the traffic matrix more efficiently, we added an additional flow entry for each pair of a source IP subnet and a destination IP subnet. This flow entry has a higher priority than the flow entry that compares only the destination IP address. The byte counters of the added flow entries can be used to measure the network flow matrix. In addition, OpenFlow does not specifically define how the weight parametes used in Group table of type select should be implemented. We believe the weight ratios should be equal to the traffic ratio. However, the current implementation of OpenvSwitch the two ratio are not equal, and no efforts were spent to ensure that the traffic ratio to be stable for the same weight ratio. We investigate three design issues in improving the implementation of Group Table of type select, and implemented our solutions for OpenvSwitch. Our experiment results indicate that using our modified OpenvSwitch, we can support multi-path routing and maintain the flow ratio equal to the weight ratio. In addition, the traffic matrix can be measured. Our experiment results also indicated that the byte counters of the flow tables on OpenVswitch only be updated about every 4.5 secs. This means that taffic matrix measured for a short interval may not be accurate. As a result, the measurements and control cycle used for network traffic engineering cannot be as short as one may desire. In addition, further investigations are needed to maintain a stable traffic ratio for multi-path routing while minimizing the re-routing traffic.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009.
Title from title screen (site viewed January 5, 2010). PDF text: xi, 178 p. : ill. ; 2 Mb. UMI publication number: AAT 3360157. Includes bibliographical references. Also available in microfilm and microfiche formats.

Today's home network usually involves connecting multiple PCs and peripheral devices, such as printers and scanners, together in a network. This provides the benefit of allowing the PCs in the network to share Internet access and other resources. However, it is expected in the future, the home area network (HAN) will grow and extend to other home devices such as home entertainment systems (including digital TV, hi-fi stereo, etc.), appliances, webcam, security alarm system, etc. Connecting other home devices to a HAN provides users with many benefits not available in today's home networks. For example, home devices capable of connecting to the future HAN are able to share the content downloaded from broadband access anywhere in the home. Users can also have remote access and control of their home devices. To extend the home area network to all these different home devices, however, means that the traffic between the ISP and future HAN will be very different from the traffic generated by today’s home network. In today's home network, which consists mainly of multiple PCs, a best-effort approach is able to satisfy the need, since most of the traffic generated by PCs is not real-time in nature. However, in future HANs, it is anticipated that traffic generated from home devices requiring real-time applications such as multimedia entertainment systems, teleconferencing, etc. will occupy a large proportion of the traffic between the ISP and future HANs. In addition, given the variety of home devices that could potentially be added to future HANs, the amount and variety of traffic between the ISP and a future HAN will certainly be very different from today's home network that is dominated by Internet/data traffic. To allow HAN users of these real-time applications and various types of home devices to continue enjoying seamless experiences in using their home devices without noticing significant delays or unnecessary interruptions, it is important for the ISP to be able to effectively manage the channel to the home so that it can provide sufficient bandwidth to ensure high QoS for home applications. The aim of this thesis is to understand the types of traffic that will be expected and to develop an analytical model that will represent the traffic behaviour between the ISP and future HANs to understand how to manage the channel to provide high QoS. In this thesis, we use the continuous-time PH/M/n/m preemptive priority queue to model the traffic behaviour between the ISP and a future HAN. Three classes of traffic are defined in this model: real-time, interactive, and unclassified. Each of these three traffic classes receives a unique priority level. From the model one can approximate the amount of bandwidth required to be allocated for each traffic class for each household so that the total bandwidth required is minimized while the QoS requirements (delay and blocking probability) of the traffic generated by the home devices are met. Thus this model could potentially be used as a network planning tool for ISPs to estimate how much bandwidth they need to provide per household for homes that use home area network. Alternatively, it could also be used to estimate what quality of service (e.g. what is the mean delay and blocking probability expected) given a certain amount of bandwidth per household.
October 2006

The information on the volume of traffic flowing between all possible origin and destination pairs in an IP network during a given period of time is generally referred to as traffic matrix (TM). This information, which is very important for various traffic engineering tasks, is very costly and difficult to obtain on large operational IP network, consequently it is often inferred from readily available link load measurements. In this thesis, we evaluated 5 TM estimation techniques, namely Tomogravity (TG), Entropy Maximization (EM), Quadratic Programming (QP), Linear Programming (LP) and Neural Network (NN) with gravity and worst-case bound (WCB) initial estimates. We found that the EM technique performed best, consistently, in most of our simulations and that the gravity model yielded better initial estimates than the WCB model. A hybrid of these techniques did not result in considerable decrease in estimation errors. We, however, achieved most significant reduction in errors by combining iterative proportionally-fitted estimates with the EM technique. Therefore, we propose this technique as a viable approach for estimating the traffic matrix of large-scale IP networks.

碩士
國立臺灣大學
機械工程學研究所
99
Intelligent vehicle (IV) systems have gathered great importance in recent year. Many driver assistance systems have been developed to improve driving safety. Traffic sign recognition system is an important subsystem of driver assistance system because it can remind the drivers of the road sign information. The proposed system comprises four modules: preprocessing, training, detection and recognition. In detection phase, a sliding window is applied to the test image in different scales. For each sliding window, we compute covariance matrix descriptor for feature extraction, and determine whether it is a sign or not. Moreover, in order to reduce computational time and false positive rate, the detector is built by Adaboost algorithm and the cascaded decision. In recognition phase, we perform the sign identification by using multi- class Support Vector Machine (SVM). The proposed algorithms were tested in sunny conditions and four different noisy outdoor scenes: occluded, faded, backlight and blurred conditions. From the experimental results, the proposed system shown high performance to detect and recognize traffic signs.

碩士
國立交通大學
土木工程研究所
83
Origin-Destination(O-D) matrix is an important data in ur- ban transportation planning. Conventional method such as home interview surveys for obtaining O-D matrix in urban areas are prone to considerable sampling error and become prohibitively costly. For these reasons several researchers try to develop methods for estimating O-D matrix from link traffic count data . Most previous research works on O-D matrix estimation conce- ntrated on rule of user-equilibrium whiich analyzes driver''s behavior, but its condition is too stringent.Therefore, the p- urpose of this thesis to develop an estimation method which is more correspond real driver''s behavior. For vehicles continue to survey at study area for five da- ys.We discover which drivers are uncertain clutch network suf- ficient information, uncertainly selects shortest path and it has the phenomenon of use habitual path. This thesis with hab- itual domains makes drivers select path basis. Assume every d- river be able select habitual path. Path habitual drive proba- bility adopts the form of logit model. Use the method of leas- t square to construct the model of O-D matrix estimation.

碩士
國立中央大學
照明與顯示科技研究所
107
LED technology is changing with each passing day. LEDs have been widely used in lighting applications, including traffic signs. In order to improve the safety of night driving, more and more traffic signs have utilized LEDs. But these traffic signs need to be evaluated. Our previous studies have evaluated four custom-made LED highway traffic signs with different designs in three aspects, including the legibility, visual comfort and preferences. Each aspect was evaluated independently at the time. The current study uses the generalized estimating equations to calculate the marginal mean as the evaluation score for each sign’s messages when legibility, visual comfort and preferences across all signs are controlled. 　　The other study in this thesis is modifying the lens design with partial backward lighting in our previous studies to be used on LED traffic signs of dot matrix type. We designed a total of 11 lenses back then, and among them two lenses were more effective and applicable. The lens that we selected for the ergonomic experiment is based on a thin plastic sleeve with one end coated with 90 % highly reflective coating. The lens was designed to be fitted on bullet-shaped LEDs, but the LEDs used on the signs have silicone on the outer layer for waterproof and dustproof. So the lens is larger than the original design. In order to be durable, the lens material is changed from acrylic to polycarbonate. The influence of the above factors increases the illumination area of the backward light, and the intensity decreases. As a result, the power ratio of front-facing light to backward light is 10.38:1, which is still within the acceptable range although it is different from the original expectation. 　　The ergonomic experiments evaluate the legibility, visual comfort and preferences of each part of the traffic sign at the distance of 75 m and 30 m. The experimental data are estimated by the method of generalized estimation equations described in the previous paragraph. Then the pairwise comparisons on the mean evaluation scores are tested in three ways, including the data of Wan word, Li word and both of them. The results show that the lens with partial backward lighting has no benefit in improving the visual quality of LED traffic signs of the dot matrix type. Nevertheless, future experiments can still try some other lenses and tune the optical design to control the illumination area and intensity of backward lighting, in order to achieve better visual quality of LED traffic signs of dot matrix type.

Nowadays Network Virtualization provides a new perspective for running multiple, relatively independent applications on same physical network (the substrate network) within shared substrate resources. This method is especially useful for researchers or investigators to get involved into networking field within a lower barrier. As for network virtualization, Virtual Network Mapping (VNM) problem is one of the most important aspects for investigation. Within years of deeply research, several efficient algorithms have been proposed to solve the Virtual Network Mapping problem, however, most of the current mapping algorithm assumes that the virtual network request topology is known or given by customers, in this thesis, a new VNM assumption based on traffic matrix is proposed, also using existing VNM benchmarks, we evaluated the mapping performance based on various metrics, and by comparing the new traffic matrix based VNM algorithm and existing ones, we provide its advantages and shortcomings and optimization to this new VNM algorithm.

碩士
國防大學管理學院
運籌管理學系
98
Abstract ”Origin-Destination (O-D) Trip Matrix” depicts the spatial distribution of trips among traffic analysis zones and the total number of trips in a transportation network. It is one of the important information required in transportation planning, specifically on traffic assignment and its applications. The data of traffic demands are difficult obtained. Traditionally, O-D pair demands need to be obtained through large-scale traffic survey. In theoretical, the observed travel flows on each link are departure from O-D pairs. If the O-D demands can be estimated from the relationships between links and paths flows and the demands on each O-D pair, it is easily to reduce the time and costs to obtain the O-D tables. For the reason, the issue of estimate the O-D demands for link traffic flows is one of the most important researches in transportation planning field. Especially the vehicle detectors are more used to direct observe link flows, the method of inferring O-D demands from link traffic flows has more application potential in transportation practice operation. In this research, we establish a linear equation system which applied the flow conservation relationship between link flows, path flows and O-D trips to solve the O-D estimation problem and develop the solution procedure. The Column Generation Method combined the Gradient Projection Method are adopted to calculate the possible paths between the O-D pairs and establish the linear equation systems. Finally, use Conditional Inverse Matrix and Hermite Form Matrix to inferring O-D Trip Matrix. Through testing, use the solution procedure in small network is inferring results accurately. The test in middle and lager network results are summarized as follows: If the Hermite Form Matrix is a unit matrix, the result is equal to original O-D demand trips. If Hermite Form Matrix is not a unit matrix, we should check the bias between the Hermite Form Matrix and unit matrix. If the bias is not too much, the method can be estimated a higher accuracy solution. To compare the traditional inferred O-D demand trips models, the model which is developed in this research can handle all of the link flow situations, whether the link flows is restricted by UE condition or not. For the future applied to the actual network, it can be observed from the test results of Hermite Form Matrix, to determine whether the inferred O-D demand trips is the real world O-D demand trips.

Networks-on-Chip (NoC) have been proposed to meet many challenges of modern Systems-on-Chip (SoC) design and manufacturing. At the architectural level, a clean separation of computation and communication helps integration and verification. Networking abstraction of the communication infrastructure also promotes reuse and fast development. But the benefit is most visible when it comes to circuit and physical design. Networks can be made sparse and regular and thus facilitate placement and route. It is also much easier to reach timing and power closure as NoC shield communication details away from complicating analysis. Last but not the least, networks are flexible at the design stage and adaptable post-silicon. Many techniques of tackling process variation and interconnect failure can be built upon NoC. However, when interconnects are time multiplexed in a NoC, the network’s performance will deteriorate if it is not scheduled properly. For a wide range of applications, the traffic on the network can be determined before run-time and offline scheduling offers guaranteed performance and enables simple design. We propose a synthesis flow that takes the data flow graph of the application and a network topology as inputs; and outputs an offline schedule that can be deployed directly to the NoC. We analyze the complexity of combinatorial problems that arise from this context and provide efficient heuristics when polynomial time algorithms are not available assuming P [not equal to] NP. Results on LDPC decoding and FFT designs are compared with previous ones. We further apply our findings to parallel shared memories (PSM) and formalize the PSM architecture and its scheduling problem. An efficient heuristic is derived from our algorithm for unbuffered networks. Another application exemplifies how the NoC can be reprogrammed after silicon is back from fab in order to avoid failed interconnects due to process variation. A simple statistical model is studied and the simulation result is rather interesting. We find out that high performance and yield are not always at conflict if we are able to change the network schedule based on silicon diagnosis.
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