Дисертації з теми "Cell transmission models"

This dissertation addresses the development and analysis of optimization models for evacuation planning. Specifically we consider the cases of large-scale regional evacuation using household vehicles and hospital evacuation. Since it is difficult to estimate the exact number of people evacuating, we first consider the case where the population size is uncertain. We review the methods studied in the literature, mainly the strategy of using a deterministic counterpart, i.e., a single deterministic parameter to represent the uncertain population, and we show that these methods are not very effective in generating a good traffic management strategy. We provide alternatives, where we describe some networks where an optimal policy exist independent of the demand realization and we propose some simple heuristics for more complex ones. Next we consider the traffic management tools that can be generated from an evacuation plan. We start by introducing the cell transmission model with flow reduction. This model captures the flow reduction after the onset of congestion. We then discuss the management tools that can be extracted from this model. We also propose some simplification to the model formulation to enhance its tractability. A heuristic for generating a solution is also proposed, and its solution quality is analyzed. Finally, we discuss the hospital evacuation problem where we develop an integer programming model that integrates the building evacuation with the transportation of patients. The impact of building evacuation capabilities on the transportation plan is investigated through the case of a large regional hospital case study. We also propose a decomposition scheme to improve the tractability of the integer program.
Ph. D.

L’objectif de ce projet est d’étudier l’interaction de nanoparticules polymères avec les membranes, soit directement sur des cellules entières ou grâce à des modèles membranaires biomimétiques, dans l’optique de valider leur utilisation dans le cadre d’applications biologiques. Des nanoparticules (NPs) polymères cœur/enveloppe avec un diamètre inférieur à 100 nm ont été synthétisés. Cette taille a été choisie afin de leur permettre de pénétrer à travers les membranes plasmiques. Des nanoparticules ayant la même composition chimique mais avec un diamètre hydrodynamique supérieur, de l’ordre de 250 nm, ont été également préparées afin de mettre en évidence l’effet de la taille des particules sur le processus d’internalisation cellulaire. Dans cette thèse, une méthode innovante de synthèse monotope a été développée pour obtenir des NPs coeur-enveloppe, compatibles en milieu aqueux et présentant à leur surface des résidus iniferter. Le coeur est composé de polystyrène avec une taille d’environ 30 nm. Un large éventail de fonctionnalités peut être greffé sur la surface du coeur par polymérisation radicalaire contrôlée en faisant varier différents types de monomères. L’épaisseur de l’enveloppe peut être ajustée en fonction de la concentration en monomère et du temps de polymérisation. Les nanoparticules synthétisées ont été caractérisées par diffusion dynamique de la lumière, par spectroscopie infrarouge à transformée de Fourier, par analyse micro-élémentaire et par microcopie à transmission électronique. Les interactions des NPs à coeur polystyrène et avec des enveloppes de charge neutre et négative ont été étudiées avec des cellules kératinocytes épidermiques humaines néonatales (NHEK), des fibroblastes primaires humains et les cellules HACaT de kératinocytes humains. Les études de cytotoxicité réalisées en utilisant un marquage à l’iodure de propidium et un test à la lactate déshydrogénase n’ont relevé aucune toxicité sur les lignées testées. Cependant, le suivi de la prolifération cellulaire par impédance électrique de substrats cellulaires a indiqué que les nanoparticules anioniques induisent une forte diminution de la prolifération des kératinocytes. L’internalisation cellulaire des NPs a été confirmée par microscopie confocale qui n’indique pas leur colocalisation avec les endosomes précoces, les lysosomes et l’actine. De plus, les données obtenues par triage cellulaire par cytofluorométrie soutiennent qu’un mécanisme énergétiquement-dépendant est mis en œuvre pour l’internalisation des NP neutres, ce qui semble être moins le cas pour les nanoparticules négatives. Les membranes biomimétiques ont été employées afin d’étudier les spécificités des interactions entre nanoparticules et lipides dans des conditions contrôlées. L’étude sur des modèles de vésicules géantes couplée à de la spectroscopie de fluorescence a révélé que les nanoparticules coeur/enveloppe sont capables d’interagir profondément dans la région hydrophobe de la membrane, mais uniquement quand la bicouche lipide est en phase fluide désordonnée. Le mode de pénétration des NPs au travers de la bicouche des vésicules semblent engendrer la formation de pores. Un effet plus prononcé de rigidification de la bicouche a pu être observé lors de l’interaction de nanoparticules chargées négativement avec les bicouches de phosphatidycholines. Cet effet pourrait être attribué à un changement de l’orientation des têtes phosphocholines du à des interactions électrostatiques. En conclusion, les nanoparticules polymère que nous avons synthétisées apparaissent être des outils polyvalents pour les études d’interaction cellulaire et d’imagerie. Ces nanomatériaux peuvent être éventuellement être employés pour la délivrance de médicaments en incorporant les molécules actives dans une enveloppe polymère thermosensible par exemple
This project’s aim was to study polymeric nanoparticle-membrane interactions using both live cells and biomimetic models with the idea to validate such nanoparticles for use in bio-applications. Core-shell polymeric nanoparticles below 100 nm, as this small size is capable of penetrating plasma membranes, were synthesised. Nanoparticles (NPs) with the same chemical composition but with hydrodynamic diameters of ~250 nm, were also prepared in an effort to highlight any effect of NP size on cell internalisation. In this thesis, an innovative method is presented for the synthesis of water-compatible, iniferter-bound polystyrene core shell NPs (~30 nm) using a one-pot synthetic method. A plethora of functionalities could be added to the nanoparticles via shell grafting from the surface of the polystyrene core in the presence of additional monomers via controlled living radical polymerisation. Shell thickness could be tuned as a function of monomer’s concentration and polymerisation time. The nanoparticles were fully characterised by dynamic light scattering, Fourier transform infra-red spectroscopy, microelemental analysis and transmission electron microscopy. Further, the interactions of polystyrene core NPs possessing neutral and anionic shells were investigated using neonatal human epidermal keratinocytes (NHEK), human primary fibroblasts and HaCaT cells. Cytotoxicity studies performed using propidium iodide and lactate dehydrogenase indicated no evidence of cytotoxicity in either cell line. However, cell proliferation monitored by electric cell substrate impedance sensing (ECIS) protocols indicated that anionic nanoparticles induced a dramatic decrease in cell proliferation in keratinocytes. The cellular internalisation of NPs was confirmed by confocal microscopy and no co-localisation was found with early endosomes, lysosomes or actin. Additionally, fluorescence activated cell sorting (FACS) data support the theory that an energy-dependent mechanism is employed for neutral NP internalisation but less so for negatively charged NPs. Biomimetic membrane models were used to investigate specific nanoparticle-lipid interactions under controlled conditions. Employing giant vesicles coupled with fluorescent spectroscopy techniques revealed that core-shell nanoparticles interact deep in the hydrophobic region of bilayers only when the membrane is in the fluid phase. Their mode of entering artificial cells (i.e giant vesicles) appears to cause the formation of pores. Anionic nanoparticles interact with the choline moiety of phosphatidylcholine and confer a rigidifying effect on phosphocholine containing bilayers. Therefore we conclude that the polymeric nanoparticles that we synthesized are versatile tools for cell interaction and imaging studies. These nanomaterials could eventually be applied to drug delivery studies by incorporation of the drug in for instance a thermoresponsive polymeric shell. Furthermore, it is clear that NPs coated with anionic and neutral polymeric shells present a lower toxicity profile than previously reported cationic nanoparticles. Both nanoparticles increase the order lipid bilayer vesicles composed of POPC (the most common glycerophospholipid) in animal and plants. Anionic nanoparticles in particular exhibit a rigidifying effect on POPC lipid bilayers and their mode of entry into cells may be due to the formation of pores which was determined to not induce cell death

L’évolution constante des technologies sans fil telles que le Wi-Fi, les normes de réseaux mobiles ou d’objets connectés, a donné naissance à de nouvelles applications et usages. Les possibilités offertes par cette multitude d’alternatives sont exploitées par les réseaux sans fil hétérogènes qui, en combinant au sein d’un réseau unique plusieurs technologies, permettent aux utilisateurs d’accéder à des services complémentaires de façon transparente. Cependant, pour bénéficier pleinement de ces avantages, plusieurs défis techniques sont à relever. L’un d’eux est relatif au déploiement de ces réseaux multi- technologies. En pratique, cette tâche s’appuie sur des règles et outils d’ingénierie afin de réaliser une planification optimale. Dans ce contexte, un objectif de la thèse a été d’établir des modèles sur lesquels peuvent se baser les outils d’ingénierie radio afin d’optimiser le déploiement de réseau locaux sans fil multi- technologies.Il s’agit principalement de calibrer des modèles de propagation pour l’estimation de couverture radio en environnement indoor résidentiel entre 800 MHz et 60 GHz; d’établir un modèle de débit pour l’estimation de capacité Wi-Fi en fonction du trafic montant et descendant; et de concevoir un modèle de résolution multi-objectif pour optimiser le positionnement de points d’accès opérant à 5 et 60 GHz. En complément, cette thèse a également proposé des recommandations pratiques visant à placer au mieux les points d’accès en phase de déploiement. Cela s’est fait par le biais d’études de sensibilité de couverture à divers facteurs, tels que l’environnement immédiat de l’émetteur ou encore la présence de personnes faisant obstruction
The constant evolution of wireless technologies such as Wi-Fi, mobile networks standards or IoT, has given rise to new applications and usages. The possibilities offered by this multitude of alternatives are exploited by heterogeneous wireless networks which, by combining within a single network several technologies, provide the users with a seamless access to complementary services. However, to take full advantage of these benefits, there are several technical issues to address. One of them is related to the deployment of these multi-technology networks. In practice, this task relies, most of the time, on radio network design software to achieve optimal planning. In such context, the main objective of this thesis is to establish models which can be used by radio network planning tools in order to the deployment of multi-technology wireless local area networks. This task has involved calibrating propagation models for radio coverage estimation, in residential indoor environments from 800 MHz to 60 GHz; developing a throughput model for Wi-Fi capacity estimation based on uplink and downlink traffic; and establishing a multi- objective resolution model to optimize the positioning of access points operating at 5 and 60 GHz. Moreover, this thesis also proposes practical recommendations for a better positioning of access points during deployment phases. This task has been achieved through coverage sensitivity studies to various factors, such as the transmitter surroundings or the presence of obstructing people

Road traffic increases constantly and the negative consequences in the form of traffic jams can be realized especially in urban areas. In order to provide real time traffic information to road users and traffic managers, accurate computer models gain relevance. A software called Mobile Millennium Stockholm (MMS) was developed to estimate and predict travel times and has been implemented on a 7km test stretch in the north of Stockholm. The core of the software is the cell transmission model (CTM) which is a macroscopic traffic flow model based on aggregated speed observations. This thesis focuses on different calibration techniques of the so called fundamental diagram as an important input factor to the CTM. The diagrams illustrate the mathematical function which defines the relation between traffic flow, density and speed. The calibration is performed in different scenarios based on the least square (LS) and total least square (TLS) error minimization. Furthermore, sources, representing the traffic demand, and sinks, representing the surrounding of the modeled network, are implemented as dynamic parameters to model the change in traffic behavior throughout the day. Split ratios, as a representation of the drivers‘ route choice in the CTM are estimated and implemented as well. For the framework of this work, the MMS software is run in a pure prediction mode. The CTM is based on the source, sink, split and fundamental diagram parameters only and run forward in time. For each fundamental diagram calibration scenario an independent model run is performed. The evaluation of the scenarios is based on the output of the model. The results are compared to existing Bluetooth travel time measurements for the test stretch, which are used as ground truth observations, and a mean average percentage error (MAPE) is calculated. This leads to a most reasonable technique for the fundamental diagram calibration – the total least square error minimization.

This study investigates how Zika virus can persist and replicate in the human prostate. It establishes a human prostate cell line model to address this question and examines the replication of three different virus strains in the cells. It also characterises the gene expression changes that occur in prostate cells during persistent Zika virus infection.

In the past, the study of Emergency Vehicle (EV) signal preemption has been mostly done using field studies. None of the simulation models that are currently commercially available have the capability to model the presence of EVs and simulate the traffic dynamics of the vehicles surrounding them. This study presents a macroscopic traffic model for examining the effect of signal preemption for EVs on traffic control measures, roadway capacity, and delays incurred to the vehicles on the side streets. The model is based on the cell transmission model, which is consistent with the hydrodynamic theory of traffic flow. A special component, in the form of a moving bottleneck that handles the traffic dynamics associated with the presence of EVs, was developed in the model. Several test scenarios were constructed to demonstrate the capabilities of the model for studying the impact of signal preemption on an arterial with multiple intersections under various traffic demand levels and varying frequencies of the arrival of EVs. Performance measures, such as average vehicle delay, maximum delay, and standard deviation of delay to traffic on all approaches, were obtained. An additional advantage of the model, apart from the capability to model EVs, is that the state-space equations used in the model can be easily incorporated into a mathematical programming problem. By coupling with a desired objective function, the model can be solved analytically. Optimal solutions can be generated to obtain insights into the development of traffic control strategies in the presence of EVs.
Master of Science

To evaluate the traffic state over time and space, several models can be used. A typical model for estimating the state of the traffic for a stretch of road or a road network is the cell transmission model, which is a form of state space model. This kind of model typically needs to be calibrated since the different roads have different properties. This thesis will present a calibration framework for the velocity based cell transmission model, the CTM-v. The cell transmission model for velocity is a discrete time dynamical system that can model the evolution of the velocity field on highways. Such a model can be fused with an ensemble Kalman filter update algorithm for the purpose of velocity data assimilation. Indeed, enabling velocity data assimilation was the purpose for ever developing the model in the first place and it is an essential part of the Mobile Millennium research project. Therefore a systematic methodology for calibrating the cell transmission is needed. This thesis presents a framework for calibration of the velocity based cell transmission model that is combined with the ensemble Kalman filter. The framework consists of two separate methods, one is a statistical approach to calibration of the fundamental diagram. The other is a black box optimization method, a simplification of the complex method that can solve inequality constrained optimization problems with non-differentiable objective functions. Both of these methods are integrated with the existing system, yielding a calibration framework, in particular highways were stationary detectors are part of the infrastructure. The output produced by the above mentioned system is highly dependent on the values of its characterising parameters. Such parameters need to be calibrated so as to make the model a valid representation of reality. Model calibration and validation is a process of its own, most often tailored for the researchers models and purposes. The combination of the two methods are tested in a suit of experiments for two separate highway models of Interstates 880 and 15, CA which are evaluated against travel time and space mean speed estimates given by Bluetooth detectors with an error between 7.4 and 13.4 % for the validation time periods depending on the parameter set and model.

The challenge to put power electronics on the same cost reduction spiral as integrated signal electronics has yet to be met. In the ongoing work for achieving complete power electronic converter integration, it has proven to be essential to develop a technology for integration of electromagnetic power passives. This integration will enable the incorporation of resonant circuits, transformers, EMI filters and the like into the integrated power electronics modules. These integrated electromagnetic power passives have been realized in terms of distributed structures, utilizing magnetic layers, conductive layers and dielectric layers. Because of the compact structures and the special implementation techniques of these integrated modules, the high frequency parasitic resonance are normally significant and may have negative impact on the performance and EMI characteristics. However, the existing modeling technique can only predict the fundamental resonant frequency and showed neither the causes of the high frequency resonance nor how to calculate those accurately. In this dissertation, comprehensive research work towards higher order electromagnetic modeling of integrated passive components is presented. Firstly, an L-C cell is identified as the basic building block of integrated passives such as an integrated series resonator. As an essential mistake in the structure evolution process of the original resonant transmission line primitive, the well-known conventional transmission line equivalent circuit as well as the equations are not applicable for the unbalanced current in an integrated passive module. For this particular application, a generalized transmission structure theory that applies to both balanced and unbalanced current has to be developed. The impedances of a generalized transmission structure with various loads and interconnections have been studied. An open-circuited load and a short-circuited load lead to series resonance and parallel resonance, respectively. The equations are substantiated with experimental results. Some preliminary study indicates the advantages of this unbalanced current passives integration technique. Since the existing integrated passive components are no other than some combination of this generalized transmission line primitive, the theoretical analysis may be applied to the further modeling of all integrated passive components. As the extension of the generalized two-conductor transmission structure model developed for the two-conductor approach, the generalized multi-conductor transmission structure theory has been proposed. As multiple L-C cells are putting in parallel, magnetic and capacitive coupling between cells cannot be neglected. To determine the capacitance between two adjacent conductors on top of the same dielectric substrate, Schwarz-Christoffel transformation and its inverse transformation have been applied with the calculation results verified by measurement. Based on the original voltage and current equations written in matrix form, modal analysis has been conducted to solve the equations. All these provide the basis for any further modeling of an integrated passive structure. Based on the basic L-C cell structure, this dissertation proposes an alternative multi-cell approach to the integration of reactive components and establishes the principles for its design and operation. It achieves the 3-D integration and has a PCB-mount chip-like structure which may have the potential to be more manufacturable, modularizable and mechanically robust. Different functional equivalents can be obtained by different PCB interconnections. The experimental results confirm the functionality as integrated reactive components for applications such as high frequency resonators. To apply the multi-conductor generalized transmission structure model to practical integrated passives structures, three typical cases have been studied: spiral-winding structure integrated series resonator, multi-cell structure integrated series resonator and integrated RF EMI filter. All these structures can be treated as one or more multi-conductor transmission structures connected in certain patterns. Different connection patterns only determine the voltage and current boundary conditions with which the equations can be solved. After obtaining the voltages and currents at each point, the impedance or transfer gain of a structure can be obtained. The MATLAB calculation results correlate well with the measurement results. The calculation sensitivities with respect to variation of various parameters are also discussed and causes of resonance at different frequency range are identified. The proposed generalized transmission structure model based on matrix modal analysis is rather complex and takes a lot of computer time especially when the number of turns is large. Furthermore, the operating frequency of an integrated resonant module is normally around its 1st resonant frequency and up to the 2nd resonant frequency. Therefore, a more simplistic higher order lumped element model which covers the operating range up to the 2nd resonant frequency may be good enough for the general design purpose. A higher order equivalent circuit model for integrated series resonant modules as an example of integrated power passives is presented in this dissertation. Inter-winding capacitance is also considered compared to the conventional 1st order approximation model. This model has been verified by small-signal test results and can be easily implemented into the design algorithm as part of the high frequency design considerations. The wide band modeling and proposed new structure mentioned above provide a comprehensive basis for better design of integrated passive components. As a general frequency plane modeling approach, the work presented in this dissertation may be extended to other passive structures, such as multi-layer capacitors, planar magnetics, etc..
Ph. D.

Traffic signals are an integral part of arterial roads, and the performance of optimized traffic signals play a critical role in managing recurrent congestion. The performance efficiency of signal control relies mainly on: a) accuracy and efficiency of traffic flow models that are used to evaluate the performance of different signal plans under various scenarios during signal optimization and b) signal designing technique used for producing signal plans. Hence, this research developed an Arterial Cell Transmission Model (ACTM) for a more realistic simulation of arterial traffic. ACTM is used to develop a Metaheuristic Robust plan Approach (MHRA) to design a robust signal plan that can maintain stable performance under varying traffic demands.

La transmission sexuelle du VIH-1 se fait principalement via du sperme infecté contaminé, contenant à la fois des virions libres et des leucocytes infectés. Les facteurs présents dans le liquide séminal peuvent aussi moduler l’infectivité du sperme et la réponse immunitaire de l’hôte. Ainsi, le macaque infecté par le virus de l’immunodéficience simienne (VIS) sera utilisé comme modèle expérimental afin d’étudier l’infectivité des cellules séminales, les réponses immunitaires anti-virales et évaluer l’effet inhibiteur d’anticorps neutralisant à large spectre (bNAbs) sur la transmission du virus intercellulaire (TVI).Chez les macaques infectés avec le SIVmac251, les réponses immunitaires innées et adaptatives spécifiques du VIS ont été étudiées dans le sperme, en se focalisant sur les réponses T CD8, humorale et sur l’expression des cytokines, chimiokines et facteurs de croissance. L’infection VIS induit l’expression de cytokines pro-inflammatoires et immuno-régulatrices dans le sperme concordant avec une augmentation des cellules activées T CD8+ CD69+ et T CD8+ CXCR3+ CCR5+. Ni les cellules T CD8+ spécifiques du VIS, ni la réponse humorale ne permettent le contrôle de la dissémination du virus dans le sperme. L’absence de contrôle de la réplication virale dans le sperme infecté VIS est associée à une inflammation générale et à une activation immunitaire, pouvant refléter ce qui se produit dans le tractus reproducteur masculin, et qui pourrait mener à l’augmentation de la transmission VIH-1/VIS.De plus, nous avons développé un modèle d’étude in vitro de TVI en utilisant soit la lignée cellulaire TZM-bl, soit des PBMC humains comme cellules cibles, et des splénocytes ou des leucocytes CD45+ du spermes infectés avec le SHIV163P3 comme cellules infectieuses. Ce modèle nous a permis d’évaluer l’inhibition de TVI par des bNAbs. Nous avons testé 4 bNabs de 1ère génération et 8 bNabs de 2nde génération. La combinaison de bNabs de 1ère génération (2F5 + 2G12 + 4E10) permet d’inhiber TVI, alors qu’en combinaison double ou seule, aucune inhibition de la transmission n’est observée. Cependant, les bNabs de 2nde génération peuvent, seules, induire une inhibition de TVI aussi efficacement qu’en combinaison. Ainsi, un bNabs de 2nde génération anti-V3 a été sélectionné afin de tester son effet inhibiteur de TVI dans un modèle in vivo
HIV-1 sexual transmission occurs mostly through contaminated semen, which contains both free virions and infected leukocytes. Moreover, factors in seminal plasma (SP) can influence both semen infectivity and host’s response. Therefore, we used the experimental model of Simian Immunodeficiency Virus (SIV) infection of macaques, to investigate semen cells infectivity and the antiviral immune responses and to evaluate the potency of broadly neutralizing antibodies (bNAbs) to block cell-to-cell virus transmission.In SIVmac251 infected cynomolgus macaques, we investigated SIV-specific innate and adaptive responses in semen, including CD8+ T cell response, humoral response and levels of cytokines, chemokines and growth factors. SIV infection induced pro-inflammatory and immunoregulatory cytokines in semen and a concomitant upregulation of activated CD69+ CD8+ T cells and CCR5+ CXCR3+ CD8+ T cells. Neither SIV-specific CD8+ T-cell responses nor humoral responses controlled seminal viral shedding. Failure to control viral replication in SIV-infected semen is related to a general inflammation and immune activation, which possibly mirrors what happen in the male genital tract and which could lead to enhanced HIV/SIV transmission.Moreover, we developed cell-to-cell transmission assays, using either TZM-bl or human PBMC as target cells and SHIV162P3-infected splenocytes and CD45+ semen leukocytes as donor cells, and evaluated bNAbs-mediated inhibition. The bNAb panel included four 1st generation bNAbs and eight 2nd generation bNAbs. A combination of 1st generation bNAbs (2F5+2G12+4E10) was able to efficiently inhibit CAV transmission, while double combination or single bNAbs showed reduced potency. Of note, individual 2nd generation bNAbs inhibited transmission as efficiently as bNAbs combinations. An anti-V3 bNAb has been selected to evaluate its potential to block cell-to-cell transmission in vivo

This diploma thesis is about creating a program to model turbulent cells of different sizes on the chosen transmission path. The initial part of the work is devoted to the formation of atmospheric turbulence and the mathematical description of the extent of turbulence and its effect on optical waves. The methods of the turbulence generation and their physical description of formation are described below. The practical part is devoted to the created program in the MATLAB.

Urban transportation networks are vulnerable to various incidents. In order to combat the negative effects due to incident-related congestion, various mitigation strategies have been proposed and implemented. The effectiveness of these congestion mitigation strategies for incident conditions largely depends on the accuracy of information regarding network conditions. Therefore, an efficient and accurate procedure to determine the link states, reflected by flows and density over time, is essential to incident management. This thesis presents a user equilibrium Dynamic Traffic Assignment (DTA) model that incorporates the Cell Transmission Model (CTM) to evaluate the temporal variation of flow and density over links, which reflect the link states of a transportation network. Encapsulation of the CTM equips the model with the capability of accepting inputs of incidents like duration and capacity reduction. Moreover, the proposed model is capable of handling multiple origin-destination (OD) pairs. By using this model, the temporal variation of flows over links can be readily evaluated. The visualized prediction of link density variations is used to investigate the link state relationships. By isolating the effects of an incident, the parallel routes of a specific OD pair display the relationship of substituting for each other, which is consistent with the general expectation regarding such parallel routes. A closer examination of the density variations confirms the existence of a substitution relationship between the unshared links of the two parallel routes. This information regarding link state relationship can be used as general guidance for incident management purposes.
Master of Science

The cell transmission model (CTM) based single destination system optimal dynamic traffic assignment (SD-SO-DTA) model has been widely applied to situations such as mass evacuations on a transportation network. Although formulated as a linear programming (LP) model, embedded multi-period cell network representation yields an extremely large model for real-size networks. As a result, most of these models are not solvable using existing LP solvers. Solutions obtained by LP also involve holding vehicles at certain locations, violating CTM flow dynamics. This doctoral research is aimed at developing innovative algorithms that overcome both computational efficiency and solution realism issues. We first prove that the LP formulation of the SD-SO-DTA problem is equivalent to the earliest arrival flow (EAF), and then develop efficient algorithms to solve EAF. Two variants of the algorithm are developed under different model assumptions and network operating conditions. For the case of time-varying network parameters, we develop a network flow algorithm on a time-expanded network. The main challenge in this approach is to address the issue of having backward wave speed lower than forward wave speed. This situation leads to non-typical constraints involving coefficients with value of less than 1. In this dissertation we develop a new network algorithm to solve this problem in optimal, even with coefficients of value less than 1. Additionally, the developed approach solves for optimal flows that exhibit non-vehicle-holding properties, which is a major breakthrough compared to all existing solution techniques for SD-SODTA. For the case of time-invariant network parameters, we reduce the SD-SO-DTA to a standard EAF problem on a dynamic network, which is constructed on the original roadway network without dividing it into cells. We prove that the EAF under free flow status is one of the optimal solutions of SD-SO-DTA, if cell properties follow a trapezoidal/triangular fundamental diagram. We use chain flows obtained on a static network to induce dynamic flows, an approach applicable to large-scale networks. Another contribution of this research is to provide a simple and practical algorithm solving the EAF with multiple sources, which has been an active research area for many years. Most existing studies involve submodular function optimization as subroutines, and thus are not practical for real-life implementation. This study’s contribution in this regard is the development of a practical algorithm that avoids submodular function optimization. The main body of the given method is comprised of |S⁺| iterations of earliest arrival s - t flow computations, where |S⁺| is the number of sources. Numerical results show that our multi-source EAF algorithm solves the SD-SO-DTA problem with time-invariant parameters to optimum.

Traffic problems caused by congestion are increasing in cities all over the world. As a traffic management tool traffic predictions can be used in order to make prevention actions against traffic congestion. There is one software for traffic state estimations called Mobile Millennium Stockholm (MMS) that are a part of a project for estimate real-time traffic information.In this thesis a framework for running traffic predictions in the MMS software have been implemented and tested on a stretch north of Stockholm. The thesis is focusing on the implementation and evaluation of traffic prediction by running a cell transmission model (CTM) forward in time.This method gives reliable predictions for a prediction horizon of up to 5 minutes. In order to improve the results for traffic predictions, a framework for dynamic inputs of demand and sink capacity has been implemented in the MMS system. The third part of the master thesis presents a model which adjusts the split ratios in a macroscopic traffic model based on driver behavior during congestion.

Aujourd’hui, plus de 80% des nouvelles infections par le virus de l’immunodéficience humaine (VIH) se produisent au cours d’un rapport sexuel, avec une transmission du virus par voie muqueuse. Le sperme constitue donc une source majeure de virus à l’échelle mondiale. Le sperme d’hommes infectés par le VIH contient le virus sous deux formes : des particules virales libres et des cellules infectées, principalement des leucocytes.Plusieurs hypothèses ont été proposées afin d’expliquer le passage du virus à travers la barrière muqueuse, qu’il s’agisse d’une muqueuse génitale (cervico-vaginale, pénienne ou urétrale) ou intestinale (muqueuse anale ou rectale). Toutefois, une grande majorité des études qui ont été menées jusqu’à présent se sont concentrées sur le rôle des particules virales libres, et celui des cellules infectées demeure mal compris. Une étude menée dans notre laboratoire a montré que des leucocytes infectés par le virus de l’immunodéficience simienne (VIS) sont capables de transmettre l’infection après inoculation vaginale.Le projet de cette thèse est d’étudier le rôle des leucocytes infectés présents dans le sperme de macaque dans la transmission muqueuse du VIS/VIH. Ainsi, trois axes d’étude principaux ont été définis: 1) l’étude des leucocytes présents dans le sperme de macaque cynomolgus, et de l’influence que peut avoir l’infection par le VIS sur eux ; 2) l’identification des cellules immunitaires infectées présentes dans le sperme de macaque, et l’étude de leur dynamique au cours de l’infection par le VIS. ; 3) l’étude du pouvoir infectieux des deux principales cellules cibles pour le VIS/VIH : les lymphocytes CD4+ (LT CD4+) et les macrophages, in vitro et in vivo, après inoculation rectale et vaginale à des macaques cynomolgus.Le sperme de macaque contient toutes les cellules cibles du VIS/VIH : des lymphocytes T CD4+ (LTCD4+), des macrophages et des cellules dendritiques dans une moindre proportion). Les LTCD4+ et les macrophages du sperme présentent un phénotype d’activation, de différenciation et d’expression de marqueurs de migration typique des leucocytes résidant dans les tissus muqueux. L’infection par le VIS induit des changements significatifs dans leur phénotype et leur dynamique. Ces deux types cellulaires peuvent être infectés de façon productive et sont présents dans le sperme à tous les stades de l’infection. Ces données suggèrent que les LTCD4+ et les macrophages du sperme seraient capables de transmettre l’infection par voie muqueuse.Si le rôle des leucocytes infectés du sperme est confirmé in vivo, il sera important à l’avenir de prendre en compte ce mécanisme de transmission dans le développement de nouvelles stratégies préventives de l’infection par le VIH, notamment les microbicides
Human Immunodeficiency Virus (HIV) infection mostly spreads by the mucosal route: sexual transmission is the dominant mode of transmission, responsible for between 85% and 90% of cases of infection worldwide. These epidemiological data indicate that semen is one of the major sources of HIV-1 transmission. Semen, like other bodily secretions involved in HIV sexual transmission, contains the virus as two forms: cell-free viral particles and cell-associated virus, mostly in infected leukocytes. Although cell-to-cell HIV transmission has been extensively described as more efficient, rapid and resistant to host immune responses, very few studies have investigated the role in vivo of infected leukocytes in virus mucosal transmission. One such study has been recently conducted in our lab, and demonstrated that SIV-infected splenocytes are able to transmit infection to female macaques after vaginal exposure. However, all these studies used immune cells from peripheral blood or lymphoid tissues, such as spleen, and none have investigated the capacity of infected leukocytes in semen to transmit the infection in vivo. Indeed, nature, phenotype and infectivity of HIV associated with semen leukocytes may be different from that of HIV from other sources.Therefore, the objectives of this work are, first, to study of semen leukocytes and their dynamics during SIVmac251 infection in detail, then to investigate seminal factors that may influence semen infectiousness, and finally to test semen leukocyte infectivity in vitro and in vivo, using a model of mucosal exposure in cynomolgus macaques.Macaque semen contains all the target cells for HIV/SIV: CD4+ T cells, macrophages and dendritic cells in lower proportions. Semen CD4+ T cells and macrophages display an activation, differenciation and expression of migration markers profile which is typical of mucosal leucocytes. SIV infection induces significant changes in their phenotype and dynamics. Both cell types can be productively infected and are found in the semen at all stages of infection. These observations suggest that semen CD4+ T cells and macrophages may be able to transmit infection after mucosal exposure.If the role of semen infected leukocytes in HIV/SIV mucosal transmission is confirmed in vivo, this mechanism will be important to consider for further preventive strategies design, like microbicides

Recent natural disasters have highlighted the need to evacuate people as quickly as possible. During hurricane Rita in 2005, people were stuck in queue buildups and large scale congestions, due to improper use of capacity, planning and inadequate response to vehicle breakdown, flooding and accidents. Every minute is precious in situation of such disaster scenarios. Understanding evacuation demand loading is an essential part of any evacuation planning. One of the factors often understood to effect evacuation, but not modeled has been the effect of a previous hurricane. This has also been termed as the 'Katrina Effect', where, due to the devastation caused by hurricane Katrina, large number of people decided to evacuate during Hurricane Rita, which hit Texas three weeks after Katrina hit Louisiana. An important aspect influencing the rate of evacuation loading is Evacuation Preparation Time also referred to as 'Mobilization time' in literature. A methodology to model the effect of a recent past hurricane on the mobilization times for evacuees in an evacuation has been presented utilizing simultaneous estimation techniques. The errors for the two simultaneously estimated models were significantly correlated, confirming the idea that a previous hurricane does significantly affect evacuation during a subsequent hurricane. The results show that the home ownership, number of individuals in the household, income levels, and level/risk of surge were significant in the model explaining the mobilization times for the households. Pet ownership and number of kids in the households, known to increase the mobilization times during isolated hurricanes, were not found to be significant in the model. Evacuation operations are marred by unexpected blockages, breakdown of vehicles and sudden flooding of transportation infrastructure. A fast and accurate simulation model to incorporate flexibility into the evacuation planning procedure is required to react to such situations. Presently evacuation guidelines are prepared by the local emergency management, by testing various scenarios utilizing micro-simulation, which is extremely time consuming and do not provide flexibility to evacuation plans. To gain computational speed there is a need to move away from the level of detail of a micro-simulation to more aggregated simulation models. The Cell Transmission Model which is a mesoscopic simulation model is considered, and compared with VISSIM a microscopic simulation model. It was observed that the Cell Transmission Model was significantly faster compared to VISSIM, and was found to be accurate. The Cell Transmission model has a nice linear structure, which is utilized to construct Linear Programming Problems to determine optimal strategies. Optimization models were developed to determine strategies for optimal scheduling of evacuation orders and optimal crossover locations for contraflow operations on freeways. A new strategy termed as 'Dynamic Crossovers Strategy' is proposed to alleviate congestion due to lane blockages (due to vehicle breakdowns, incidents etc.). This research finds that the strategy of implementing dynamic crossovers in the event of lane blockages does improve evacuation operations. The optimization model provides a framework within which optimal strategies are determined quickly, without the need to test multiple scenarios using simulation. Destination networks are the cause of the main bottlenecks for evacuation routes, such aspects of transportation networks are rarely studied as part of evacuation operations. This research studies destination networks from a macroscopic perspective. Various relationships between network level macroscopic variables (Average Flow, Average Density and Average speed) over the network were studied. Utilizing these relationships, a "Network Breathing Strategy" was proposed to improve dissipation of evacuating traffic into the destination networks. The network breathing strategy is a cyclic process of allowing vehicles to enter the network till the network reaches congestion, which is followed by closure of their entry into the network until the network reaches an acceptable state. After which entrance into the network is allowed again. The intuitive motivation behind this methodology is to ensure that the network does not remain in congested conditions. The term 'Network Breathing' was coined due to the analogy seen between this strategy to the process of breathing, where vehicles are inhaled by the network (vehicles allowed in) and dissipated by the network (vehicles are not allowed in). It is shown that the network breathing improves the dissipation of vehicle into the destination network. Evacuation operations can be divided into three main levels: at the origin (region at risk), routes and destination. This research encompasses all the three aspects and proposes a framework to assess the whole system in its entirety. At the Origin the demand dictates when to schedule evacuation orders, it also dictates the capacity required on different routes. These breakthroughs will provide a framework for a real time Decision Support System which will help emergency management official make decisions faster and on the fly.
Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering PhD

Human Immunodeficiency Virus (HIV) infection mostly spreads by the mucosal route: sexual transmission is the dominant mode of transmission, responsible for between 85% and 90% of cases of infection worldwide. These epidemiological data indicate that semen is one of the major sources of HIV-1 transmission. Semen, like other bodily secretions involved in HIV sexual transmission, contains the virus as two forms: cell-free viral particles and cell-associated virus, mostly in infected leukocytes. Although cell-to-cell HIV transmission has been extensively described as more efficient, rapid and resistant to host immune responses, very few studies have investigated the role in vivo of infected leukocytes in virus mucosal transmission. One such study has been recently conducted in our lab, and demonstrated that SIV-infected splenocytes are able to transmit infection to female macaques after vaginal exposure. However, all these studies used immune cells from peripheral blood or lymphoid tissues, such as spleen, and none have investigated the capacity of infected leukocytes in semen to transmit the infection in vivo. Indeed, nature, phenotype and infectivity of HIV associated with semen leukocytes may be different from that of HIV from other sources.Therefore, the objectives of this work are, first, to study of semen leukocytes and their dynamics during SIVmac251 infection in detail, then to investigate seminal factors that may influence semen infectiousness, and finally to test semen leukocyte infectivity in vitro and in vivo, using a model of mucosal exposure in cynomolgus macaques.Macaque semen contains all the target cells for HIV/SIV: CD4+ T cells, macrophages and dendritic cells in lower proportions. Semen CD4+ T cells and macrophages display an activation, differenciation and expression of migration markers profile which is typical of mucosal leucocytes. SIV infection induces significant changes in their phenotype and dynamics. Both cell types can be productively infected and are found in the semen at all stages of infection. These observations suggest that semen CD4+ T cells and macrophages may be able to transmit infection after mucosal exposure.If the role of semen infected leukocytes in HIV/SIV mucosal transmission is confirmed in vivo, this mechanism will be important to consider for further preventive strategies design, like microbicides.

Thin-film solar cells are widely recognised to have the potential to compete with fossil fuels in the electricity market due to their low cost per peak Watt. The Thin-Film Group at the University of New South Wales (UNSW) is engaged in developing polycrystalline silicon (poly-Si) thin-film solar cells on glass using e-beam evaporation technology. We believe our solar cells have the potential of significantly lowering the manufacturing cost compared to conventional, PECVD-fabricated thin-film solar cells. After years of materials research, the focus of the Group??s work is now moving to the metallisation of evaporated solar cells. Minimising various kinds of losses is the main challenge of the cell metallisation procedure, within which the contact resistance is always a big issue. In this thesis, the contact resistance of aluminium contacts on poly-Si thin-film solar cells on glass is investigated. To the best of the author??s knowledge, this is the first ever contact resistance investigation of Al contacts on evaporated poly-Si material for photovoltaic applications. Various transmission line models (TLM) are employed to measure the contact resistance. An improved TLM model is developed to increase the measurement precision and, simultaneously, to simplify the TLM pattern fabrication process. In order to accommodate the particular requirements of poly-Si coated glass substrates, a TLM pattern fabrication process using photolithography is established. Furthermore, a Kelvin sense tester is set up to ensure an accurate measurement of the contact resistance. After establishment of the TLM technique at UNSW, it is successfully tested on singlecrystalline silicon wafer samples. The thermal annealing process of the contacts is also optimised. Then, the general behaviour of Al contacts on uniformly doped poly-Si films (i.e., no p-n junction) is investigated using the verified TLM technique. The long-term stability of the contacts is also studied. This is followed by an investigation of the contact resistance of the back surface field and emitter layers of different types of poly-Si thin-film solar cells. Finally, a novel contact resistance measurement model is proposed that is believed to be able to overcome the measurement bottleneck of the transmission line models.

Les interneurones GABAergiques du néocortex, englobent un grand nombre de types cellulaires: certains innervent la région périsomatique des neurones pyramidaux (NP), d'autres ciblent leurs dendrites. Ici, nous avons étudié la sous-unité alpha5 du récepteur GABAA(GABAAR), qui contribuerait significativement à l’inhibition tonique. Nous avons constaté que, dans les NP de la couche 2/3 du cortex somatosensoriel chez la souris, alpha5 a une contribution négligeable à l'inhibition tonique. Inversement nous avons montré qu’alpha5 est spécifiquement exprimée aux synapses dendritiques entre les cellules de Martinotti (MC) et les NP, indiquant l’importance des alpha5-GABAARs dans l’inhibition dendritique synaptique. Nous avons aussi montré qu’alpha5 est exclusivement exprimé aux synapses MC-NP, en proposant les alpha5-GABAARs comme signature moléculaire spécifique de ces synapses dendritiques. En plus, des nombreuses maladies du cerveau sont le résultat du dysfonctionnement de circuits inhibiteurs distincts: par exemple, il a été montré que le traitement avec un agoniste inverse spécifique du récepteur alpha5-GABAA(alpha5IA) a permis la récupération des déficits cognitifs chez des modèles animaux de trisomie 21(DS) mais les mécanismes de cette récupération cognitive sont inconnus au niveau du circuit. Nos résultats préliminaires indiquent que les synapses GABAergiques dendritiques formées par les MCs sont spécifiquement modifiées chez les souris DS. Nous définirons si cette modification est spécifique à un circuit particulier. Nos expériences visent à comprendre les altérations spécifiques des circuits de la DS afin d’ouvrir de nouvelles pistes thérapeutiques
Neocortical GABAergic interneurons encompass a vast number of cell types: some innervate the perisomatic region of cortical pyramidal neurons (PNs), whereas others target PN dendrites. Here we studied the alpha5 subunit of the GABAAR, which is believed to contribute significantly to tonic inhibition. We found that, in L 2/3 PNs of mouse somatosensory cortex, alpha5 provides a negligible contribution to tonic inhibition. Conversely, we found that alpha5 is specifically expressed at synapses between the dendrite-targeting interneurons Martinotti cells (MCs) thus indicating that GABAergic transmission through 5-GABAAR subtypes is important for synaptic dendritic inhibition. We also show that the expression of alpha5 is always present only at synapses made by MCs onto PNs. These results suggest alpha5-GABAARs as a molecular signature of specific inhibitory dendritic synapses involving MCs. Importantly, many brain diseases originate from dysfunctions of distinct inhibitory circuits and, in particular, alpha5-KO mice show improved learning: it was shown that the treatment with a highly specific alpha5 inverse agonist rescued learning and memory deficits in Ts65Dn mice, an animal model for Down syndrome (DS). Yet, the actual mechanisms underlying this cognitive rescue at the synaptic and circuit levels are unknown. Our preliminary results indicate that GABAergic synapses from dendrite-targeting MCs are specifically altered in DS. We are defining whether this alteration is circuit-specific. Our results will provide a better understanding of specific circuit alterations in DS, and will likely open new therapeutic avenues to alleviate cognitive impairment of this disease

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

This research investigated strategies for motorway congestion management from a different angle: that is, how to quickly recover motorway from congestion at the end of peak hours, given congestion cannot be eliminated due to excessive demand during the long peak hours nowadays. The project developed a zone recovery strategy using ramp metering for rapid congestion recovery, and a serious of traffic simulation investigations were included to evaluate the developed strategy. The results, from both microscopic and macroscopic simulation, demonstrated the effectiveness of the zone recovery strategy.

This research contributes to the state of the art and state of the practice in solving a very important and computationally challenging problem in the areas of urban transportation systems, operations research, disaster management, and public policy. Being a very active topic of research during the past few decades, the problem of developing an efficient and practical strategy for evacuation of real-sized urban traffic networks in case of disasters from different causes, quickly enough to be employed in immediate disaster management scenarios, has been identified as one of the most challenging and yet vital problems by many researchers. More specifically, this research develops fast methods to find the optimal integrated strategy for traffic routing and traffic signal control to evacuate real-sized urban networks in the most efficient manner. In this research a solution framework is proposed, developed and tested which is capable of solving these problems in very short computational time. An efficient relaxation-based decomposition method is proposed, implemented for two evacuation integrated routing and signal control model formulations, proven to be optimal for both formulations, and verified to reduce the computational complexity of the optimal integrated routing and signal control problem. The efficiency of the proposed decomposition method is gained by reducing the integrated optimal routing and signal control problem into a relaxed optimal routing problem. This has been achieved through an insight into intersection flows in the optimal routing solution: in at least one of the optimal solutions of the routing problem, each street during each time interval only carries vehicles in at most one direction. This property, being essential to the proposed decomposition method, is called "unidirectionality" in this dissertation. The conditions under which this property exists in the optimal evacuation routing solution are identified, and the existence of unidirectionality is proven for: (1) the common Single-Destination System-Optimal Dynamic Traffic Assignment (SD-SODTA) problem, with the objective to minimize the total time spent in the threat area; and, (2) for the single-destination evacuation problem with varying threat levels, with traffic models that have no spatial queue propagation. The proposed decomposition method has been implemented in compliance with two widely-accepted traffic flow models, the Cell Transmission Model (CTM) and the Point Queue (PQ) model. In each case, the decomposition method finds the optimal solution for the integrated routing and signal control problem. Both traffic models have been coded and applied to a realistic real-size evacuation scenario with promising results. One important feature that is explored is the incorporation of evacuation safety aspects in the optimization model. An index of the threat level is associated with each link that reflects the adverse effects of traveling in a given threat zone on the safety and health of evacuees during the process of evacuation. The optimization problem is then formulated to minimize the total exposure of evacuees to the threat. A hypothetical large-scale chlorine gas spill in a high populated urban area (downtown Tucson, Arizona) has been modeled for testing the evacuation models where the network has varying threat levels. In addition to the proposed decomposition method, an efficient network-flow solution algorithm is also proposed to find the optimal routing of traffic in networks with several threat zones, where the threat levels may be non-uniform across different zones. The proposed method can be categorized in the class of "negative cycle canceling" algorithms for solving minimum cost flow problems. The unique feature in the proposed algorithm is introducing a multi-source shortest path calculation which enables the efficient detection and cancellation of negative cycles. The proposed method is proven to find the optimal solution, and it is also applied to and verified for a mid-size test network scenario.

[EN] Phononic crystals are artificial materials formed by a periodic arrangement of inclusions embedded into a host medium, where each of them can be solid or fluid. By controlling the geometry and the impedance contrast of its constituent materials, one can control the dispersive properties of waves, giving rise to a huge variety of interesting and fundamental phenomena in the context of wave propagation. When a propagating wave encounters a medium with different physical properties it can be transmitted and reflected in lossless media, but also absorbed if dissipation is taken into account. These fundamental phenomena have been classically explained in the context of homogeneous media, but it has been a subject of increasing interest in the context of periodic structures in recent years as well. This thesis is devoted to the study of different effects found in sonic and phononic crystals associated with transmission, reflection and absorption of waves, as well as the development of a technique for the characterization of its dispersive properties, described by the band structure. We start discussing the control of wave propagation in transmission in conservative systems. Specifically, our interest is to show how sonic crystals can modify the spatial dispersion of propagating waves leading to control the diffractive broadening of sound beams. Making use of the spatial dispersion curves extracted from the analysis of the band structure, we first predict zero and negative diffraction of waves at frequencies close to the band-edge, resulting in collimation and focusing of sound beams in and behind a 3D sonic crystal, and later demonstrate it through experimental measurements. The focusing efficiency of a 3D sonic crystal is limited due to the strong scattering inside the crystal, characteristic of the diffraction regime. To overcome this limitation we consider axisymmetric structures working in the long wavelength regime, as a gradient index lens. In this regime, the scattering is strongly reduced and, in an axisymmetric configuration, the symmetry matching with acoustic sources radiating sound beams increase its efficiency dramatically. Moreover, the homogenization theory can be used to model the structure as an effective medium with effective physical properties, allowing the study of the wave front profile in terms of refraction. We will show the model, design and characterization of an efficient focusing device based on these concepts. Consider now a periodic structure in which one of the parameters of the lattice, such as the lattice constant or the filling fraction, gradually changes along the propagation direction. Chirped crystals represent this concept and are used here to demonstrate a novel mechanism of sound wave enhancement based on a phenomenon known as "soft" reflection. The enhancement is related to a progressive slowing down of the wave as it propagates along the material, which is associated with the group velocity of the local dispersion relation at the planes of the crystal. A model based on the coupled mode theory is proposed to predict and interpret this effect. Two different phenomena are observed here when dealing with dissipation in periodic structures. On one hand, when considering the propagation of in-plane sound waves in a periodic array of absorbing layers, an anomalous decrease in the absorption, combined with a simultaneous increase of reflection and transmission at Bragg frequencies is observed, in contrast to the usual decrease of transmission, characteristic in conservative periodic systems at these frequencies. For a similar layered media, backed now by a rigid reflector, out-of-plane waves impinging the structure from a homogeneous medium will increase dramatically the interaction strength. In other words, the time delay of sound waves inside the periodic system will be considerably increased resulting in an enhanced absorption, for a broadband spectral range.
[ES] Los cristales fonónicos son materiales artificiales formados por una disposición periódica de inclusiones en un medio, pudiendo ambos ser de carácter sólido o fluido. Controlando la geometría y el contraste de impedancias entre los materiales constituyentes se pueden controlar las propiedades dispersivas de las ondas. Cuando una onda propagante se encuentra un medio con diferentes propiedades físicas puede ser transmitida y reflejada, en medios sin pérdidas, pero también absorbida, si la disipación es tenida en cuenta. La presente tesis está dedicada al estudio de diferentes efectos presentes en cristales sónicos y fonónicos relacionados con la transmisión, reflexión y absorción de ondas, así como el desarrollo de una técnica para la caracterización de sus propiedades dispersivas, descritas por la estructura de bandas. En primer lugar, se estudia el control de la propagación de ondas en transmisión en sistemas conservativos. Específicamente, nuestro interés se centra en mostrar cómo los cristales sónicos son capaces de modificar la dispersión espacial de las ondas propagantes, dando lugar al control del ensanchamiento de haces de sonido. Haciendo uso de las curvas de dispersión espacial extraídas del análisis de la estructura de bandas, se predice primero la difracción nula y negativa de ondas a frecuencias cercanas al borde de la banda, resultando en la colimación y focalización de haces acústicos en el interior y detrás de un cristal sónico 3D, y posteriormente se demuestra mediante medidas experimentales. La eficiencia de focalización de un cristal sónico 3D está limitada debido a las múltiples reflexiones existentes en el interior del cristal. Para superar esta limitación se consideran estructuras axisimétricas trabajando en el régimen de longitud de onda larga, como lentes de gradiente de índice. En este régimen, las reflexiones internas se reducen fuertemente y, en configuración axisimétrica, la adaptación de simetría con fuentes acústicas radiando haces de sonido incrementa la eficiencia drásticamente. Además, la teoría de homogenización puede ser empleada para modelar la estructura como un medio efectivo con propiedades físicas efectivas, permitiendo el estudio del frente de ondas en términos refractivos. Se mostrará el modelado, diseño y caracterización de un dispositivo de focalización eficiente basado en los conceptos anteriores. Considérese ahora una estructura periódica en la que uno de los parámetros de la red, sea el paso de red o el factor de llenado, cambia gradualmente a lo largo de la dirección de propagación. Los cristales chirp representan este concepto y son empleados aquí para demostrar un mecanismo novedoso de incremento de la intensidad de la onda sonora basado en un fenómeno conocido como reflexión "suave". Este incremento está relacionado con una ralentización progresiva de la onda conforme se propaga a través del material, asociado con la velocidad de grupo de la relación de dispersión local en los planos del cristal. Un modelo basado en la teoría de modos acoplados es propuesto para predecir e interpretar este efecto. Se observan dos fenómenos diferentes al considerar pérdidas en estructuras periódicas. Por un lado, si se considera la propagación de ondas sonoras en un array periódico de capas absorbentes, cuyo frente de ondas es paralelo a los planos del cristal, se produce una reducción anómala en la absorción combinada con un incremento simultáneo de la reflexión y transmisión a las frecuencias de Bragg, de forma contraria a la habitual reducción de la transmisión, característica de sistemas periódicos conservativos a estas frecuencias. En el caso de la misma estructura laminada en la que se cubre uno de sus lados mediante un reflector rígido, la incidencia de ondas sonoras desde un medio homogéneo, cuyo frente de ondas es perpendicular a los planos del cristal, produce un gran incremento de la fuerza de
[CAT] Els cristalls fonònics són materials artificials formats per una disposició d'inclusions en un medi, ambdós poden ser sòlids o fluids. Controlant la geometría i el contrast d'impedàncies dels seus materials constituents, és poden controlar les propietats dispersives de les ondes, permetent una gran varietatde fenòmens fonamentals interessants en el context de la propagació d'ones. Quan una ona propagant troba un medi amb pèrdues amb propietats físiques diferents es pot transmetre i reflectir, però també absorbida si la dissipació es té en compte. Aquests fenòmens fonamentals s'han explicat clàssicament en el context de medis homogenis, però també ha sigut un tema de creixent interés en el context d'estructures periòdiques en els últims anys. Aquesta tesi doctoral tracta de l'estudi de diferents efectes en cristalls fonònics i sònics lligats a la transmissió, reflexió i absorció d'ones, així com del desenvolupament d'una tècnica de caracterització de les propietats dispersives, descrites mitjançant la estructura de bandes. En primer lloc, s'estudia el control de la propagació ondulatori en transmissió en sistemes conservatius. Més específicament, el nostre interés és mostrar com els cristalls sonors poden modificar la dispersió espacial d'ones propagants donant lloc al control de l'amplària per difracció dels feixos sonors. Mitjançant les corbes dispersió espacial obtingudes de l'anàlisi de l'estructura de bandes, es prediu, en primer lloc, la difracció d'ones zero i negativa a freqüències próximes al final de banda. El resultat és la collimació i focalització de feixos sonors dins i darrere de cristalls de so. Després es mostra amb mesures experimentals. L'eficiència de focalització d'un cristall de so 3D està limitada per la gran dispersió d'ones dins del cristall, que és característic del règim difractiu. Per a superar aquesta limitació, estructures axisimètriques que treballen en el règim de llargues longituds d'ona, i es comporten com a lents de gradient d'índex. En aquest règim, la dispersió es redueix enormement i, en una configuració axisimètrica, a causa de l'acoblament de la simetría amb les fonts acústiques que radien feixos sonors, l'eficiència de radiació s'incrementa significativament. D'altra banda, la teoria d'homogeneïtzació es pot utilitzar per a modelar, dissenyar i caracteritzar un dispositiu eficient de focalització basat en aquests conceptes. Considerem ara una estructura periòdica en la qual un dels seus paràmetres de xarxa, com ara la constant de xarxa o el factor d'ompliment canvia gradualment al llarg de la direcció de propagació. Els cristalls chirped representen aquest concepte i s'utilitzen ací per a demostrar un mecanisme nou d'intensificació d'ones sonores basat en el fenòmen conegut com a reflexió "suau". La intensificació està relacionada amb la alentiment progressiva de l'ona conforme propaga al llarg del material, que està associada amb la velocitat de grup de la relació de dispersió local en els diferents plànols del cristall. Es proposa un model basat en la teoria de modes acoblats per a predir i interpretar este efecte. Dos fenòmens diferents cal destacar quan es tracta d'estructures periòdiques amb dissipació. Per un costat, al considerar la propagació d'ones sonores en el plànol en un array periòdic de capes absorbents, s'observa una disminució anòmala de l'absorció i es combina amb un augment simultani de reflexió i transmissió en les freqüències de Bragg que contrasta amb la usual disminució de transmissió, característica dels sistemes conservatius a eixes freqüències. Per a un medi similar de capes, amb un reflector rígid darrere, les ones fora del pla incidint l'estructura des de un medi homogeni, augmentaran considerablement la interacció. En altres paraules, el retràs temporal de les ones sonores dins del sistema periòdic augmentarà significativament produint un augmen
Cebrecos Ruiz, A. (2015). Transmission, reflection and absorption in Sonic and Phononic Crystals [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/56463
TESIS
Premiado

Synaptic plasticity—the ability of a synapse to change—is fundamental to basic brain function and behavioral adaptation. Studying the mechanisms of synaptic plasticity benefits our understanding of the formation of neuronal connections and circuitry, which has great implications in the field of learning and memory and the studies of numerous human diseases. The Drosophila larval neuromuscular junction (NMJ) system is a powerful system for studying synaptic plasticity. The NMJ consists of at least two different types of motorneurons innervating the body wall muscles. Type I motorneurons controls muscle contraction using glutamate as the neurotransmitter, while type II are modulatory neurons that contain octopamine. Octopamine is a potent modulator of behavior in invertebrates. Nevertheless, its function at the synapse is poorly understood. In my thesis research, I investigated the role of octopamine in synaptic plasticity using the Drosophila NMJ system. Preliminary observations indicate that increased larval locomotion during starvation results in an increase of filopodia-like structures at type II terminals. These structures, which we termed as “synaptopods” in our previous studies, contain synaptic proteins and can mature into type II synapses. I demonstrated that this outgrowth of type II terminals is dependent on activity and octopamine. Mutations and genetic manipulations affecting the production of octopamine decrease synaptopods, whereas increase of type II activity or exogenous application of octopamine increase synaptopods. Interestingly, I found that the type II octopaminergic neurons have an absolute dependence on activity for their innervation of the muscles. Blocking activity in these neurons throughout development results in no type II synapses at the NMJ, whereas blocking activity after the formation of synapses results in gradual degradation of type II terminals. Next, I examined the autoregulatory mechanism underlying the octopamine-induced synaptic growth in octopaminergic neurons. I discovered that this positive-feedback mechanism depends on an octopamine autoreceptor, Octß2R. This receptor in turn activates a cAMP- and CREB-dependent pathway that is required in the octopamine-induction of synaptopods. Furthermore, I demonstrated that this octopaminergic autoregulatory mechanism is necessary for the larva to properly increase its locomotor activity during starvation. Thirdly, I investigated the possibility that type II innervation might regulate type I synaptic growth through octopamine. We found that ablation, blocking of type II activity, or the absence of octopamine results in reduced type I outgrowth, and this paracrine signaling is mediated by Octß2R which is also present in type I motorneurons. Lastly, the function of another octopamine receptor, Octß1R, was examined. In contrast to Octß2R, Octß1R is inhibitory to synaptic growth. I demonstrated that the inhibitory effect of this receptor is likely accomplished through the inhibitory G-protein Goα. Similar to Octß2R, Octß1R also regulates the synaptic growth of both type I and type II motorneurons in a cell-autonomous manner. The inhibitory function of this receptor potentially breaks the positive feedback loop mediated by Octß2R, allowing the animal to reset its neurons when the environment is favorable. In summary, the research presented in this thesis has unraveled both autoregulatory and paracrine mechanisms in which octopamine modulates synaptic and behavior plasticity through excitatory and inhibitory receptors.

Selon le rapport de la Commission Européenne (2011), le départ du dirigeant d’une entreprise se traduit trop souvent par la disparition de cette dernière. Face à l’ampleur du phénomène de reprise par un tiers physique externe, force est de constater le manque de travaux consacrés à cette modalité entrepreneuriale (Durst et Wilhelm, 2009 ; Parker et van Praag, 2012) alors que de moins en moins de descendants sont prêts à prendre la relève (TRANSREGIO, 2005). L’un des challenges auxquels fait face le repreneur (personne physique) est lié à la nécessité d’apprendre et de comprendre rapidement un système complexe dont il assumera sous peu la responsabilité. Ce travail doctoral relève le risque de faux pas du repreneur défini comme une action allant, sans que ce dernier en ait conscience, à l’encontre de la marche normale de l’entreprise. Le cadre opératoire déployé met au jour la représentation que possède le repreneur du Business Model de l’entreprise transmise pour la comparer à celle du cédant et ainsi révéler des types d’écart susceptibles de conduire à des faux pas.Après un cas exploratoire, quatre cas de transmission ont été étudiés sur la base d’entretiens semi-directifs ayant permis de produire une version narrative des Business Models. Pour chacun des cas, la comparaison systématique de la représentation du repreneur à celle du cédant a permis l’observation de cinq cas de figure : carence, dissonance, concordance, précellence et modèles différents
According to the report of the European Commission (2011), owner-manager departures lead too often to the demise of the firm. Faced with the worrying growth of this phenomenon, little research has been conducted on non-family business successions (Durst et Wilhelm, 2009 ; Parker et van Praag, 2012) while fewer and fewer descendants are willing to take on the succession (TRANSREGIO, 2005), little research has been conducted on non-family business succession (Durst & Wilhelm, 2009). One of the main challenges faced by the buyer (individual) is to rapidly learn and understand a complex system which is going to be under his or her guidance. Our research brings to light the risk of faux pas which we define as a decision of the buyer which goes against the ordinary working of the firm, without the buyer being aware of it. Our research protocol formalises the buyer’s representation regarding the Business Model of the firm he buys to compare it with the seller’s one. This comparison reveals types of deviations likely to lead to faux pas.After an exploratory investigation, four cases of business transfer have been studied using a semi-structured checklist allowing us to produce a written version of the Business Models. For each case, a systematic comparison of the buyer’s and the seller’s representations allowed us to draw some conclusions bringing to light five situations: shortcomings, discordance, concordance, superiority and different models

Dans un avion, un hélicoptère ou un lanceur actuel, des milliers de capteurs, pour la plupart non critiques sont utilisés pour la mesure de divers paramètres (températures, pressions, positions...) Les résultats sont ensuite acheminés par des fils vers les calculateurs de bord qui les traitent. Ceci implique la mise en place de centaines de kilomètres de câbles (500 km pour un avion de ligne) dont le volume est considérable. Il en résulte une grande complexité de conception et de fabrication, des problèmes de fiabilité, notamment au niveau des connexions, et une masse importante. Par ailleurs l'instrumentation de certaines zones est impossible car leur câblage est difficilement envisageable par manque d'espace. En outre, s'il est souvent intéressant d'installer de nouveaux capteurs pour faire évoluer un aéronef ancien, l'installation des câbles nécessaires implique un démantèlement partiel, problématique et coûteux, de l'appareil. Pour résoudre ces problèmes, une idée innovante a émergé chez les industriels de l'aéronautique : commencer à remplacer les réseaux filaires reliant les capteurs d'un aéronef et leur centre de décision par des réseaux sans fil. Les technologies de communication sans fil sont aujourd'hui largement utilisées dans les marchés de l'électronique de grande consommation. Elles commencent également à être déployées pour des applications industrielles comme l'automobile ou le relevé à distance de compteurs domestiques. Cependant, remplacer des câbles par des ondes représente un défi technologique considérable comme la propagation en milieu confiné, la sécurité, la sureté de fonctionnement, la fiabilité ou la compatibilité électromagnétique. Cette thèse est motivée d'une part par l'avancée non négligeable dans le milieu aérospatial que pourrait être l'établissement d'un réseau sans fil à bord d'aéronefs dans la résolution de problématique classiques comme l'allégement et l'instrumentation. Il en résulterait donc : * Une meilleure connaissance de l'environnement et de la santé de l'aéronef * Un gain sur le poids. * Un gain en flexibilité. * Un gain en malléabilité et en évolutivité. * Un gain sur la complexité. * Un gain sur la fiabilité D'autre part, étant donnée la complexité de la conception de ce réseau de capteur sans fil, il a été nécessaire d'appliquer une méthodologie évolutive et adaptée mais inspirée de l'ingénierie système. Il est envisageable, vu le nombre de sous-systèmes à considérer, que cette méthodologie soit réutilisable pour d'autre cas pratiques. Une étude aussi complète que possible a été réalisée autour de l'existant déjà établi sur le sujet. En effet, on peut en lisant ce mémoire de thèse avoir une idée assez précise de ce qui a été fait. Une liste a été dressée de toutes les technologies sans fil en indiquant leur état de maturité, leurs avantages et leurs inconvénients afin de préciser les choix possibles et les raisons de ces choix. Des projets de capteurs sans fil ont été réalisés, des technologies sans fil performantes et personnalisables ont été développées et arrivent à maturité dans des secteurs variés tels que la domotique, la santé, l'automobile ou même l'aéronautique. Cependant aucun capteur sans fil n'a été véritablement installé en milieu aérospatial car de nombreux verrous technologiques n'ont pas été levés. Fort des expériences passées, et de la maturité qu'ont prise certaines technologies, des conclusions ont été tirées des projets antérieurs afin de tendre vers des solutions plus viables. Une fois identifiés, les verrous technologiques ont été isolés. Une personnalisation de notre solution a été à envisager afin de remédier tant que faire se peut à ces points bloquants avec les moyens mis à disposition. La méthodologie appliquée nous a permis d'identifier un maximum de contraintes, besoins et exigences pour mieux focaliser les efforts d'innovation sur les plus importantes et choisir ainsi les technologies les plus indiquées.

碩士
國立交通大學
交通運輸研究所
98
Cell transmission model (CTM), proposed by Daganzo (1994; 1995), is a mesoscopic traffic flow model which can efficiently simulate traffic hydrodynamics under various traffic conditions. CTM can provide a convergent approximation to the Lighthill and Whiteham (1955) and Richard (1956) (LWR) models and covers the entire fundamental diagram. Due to its low computation requirements compared with micro-simulation models, CTM is widely applied to simulate the traffic flow behaviors at freeways and signalized intersection. The conventional CTM was designed for pure traffic, i.e. all vehicles are of the same size such as cars on freeways. Incorporation of more realistic CTM rules into the simulation of mixed traffic (various types of vehicles such as cars and motorcycles) on urban streets is comparatively less addressed. However, it is ubiquitous in many Asian urban streets that motorcycles oftentimes move concurrently with the cars by sharing the “same lane”. Some erratic motorcyclists do not even follow the lane disciplines at all. They may make lateral drifts breaking into two moving cars. Once blocked by the front vehicles, they even make wide transverse crossings through the gap of two stationary cars in the same lane, in order to move forward. That is, even the downstream cell is fully occupied by cars, motorcycles can still move forward. These erratic behaviors of motorcycles in the lateral clearance among larger vehicles would definitely increase the storage capacity of a cell. Without considerations of such behaviors and interaction between different sized vehicles, the traffic simulation might obtain a misleading result. Based on this, this study proposes mixed traffic cell transmission models (MCTM) to replicate the behaviors of mixed traffic consisted of cars and motorcycles. Both types of vehicles exhibit rather different traffic behaviors in competing roadway capacity and remaining storage space. Thus, the parameters of the MCTM, including maximal flow rate, maximal storage capacity, and remaining storage capacity, should be dynamically adjusted and allocated between cars and motorcycles according to mixture ratio of vehicles types and the traffic phases – free flow, synchronized, and congested. Based on our field observations, two MCTM models are developed. The first MCTM model uses the ratio of car to motorcycle in the last upstream cell to determine the amount of roadway resources (i.e. capacity and storage capacity) allocated to cars, and vice versa for motorcycles. That is, the larger value of car to motorcycle ratio is, the more advantageous of car in competing the roadway resource is. The second MCTM model further incorporates an entropy index to adjust the traffic speed, since the interferences between two types of vehicles will be rapidly increased as the mixture ratio of cars and motorcycles becomes higher. To validate the proposed MCTM models, videotaping traffic data of three corridors in Taipei city covering a full traffic spectrum from free-flow to congested are collected. Since the traffic behaviors will be significantly affected by the passengers embarking and disembarking maneuvers of bus traffic, to exclude such interactions, the corridors with a bus exclusive lane, Sec. 4, Roosevelt Road, are selected. The results show that the both proposed MCTM models can accurately simulate the traffic flows under various traffic phases and mixture ratios with an average MAPE (mean absolute percentage error) below 30%. The simulation accuracy is also compared spatially (different cells) and temporally (green time vs. red time, off-peak hour vs. peak hour).

碩士
國立交通大學
運輸與物流管理學系
105
The macroscopic traffic flow models which account for the flow rate, density or speed of groups of vehicles on the roads, are advantageous to its high efficiency. On the contrary, the microscopic traffic flow models deal with the stimulation terms to spacing or relative speed between individual vehicles and respond to its acceleration or deceleration. The advantage of them lie in describing detailed vehicle behaviors and high accuracy. Therefore, it is necessary to be confronted with a trade-off between efficiency and accuracy when conducting mixed traffic flow models simulation. This study takes the prevailing mixed traffic of cars and motorcycles on urban streets as the background. Firstly, based on the mixed traffic cell transmission models (MCTM), proposed by C.W. Hsieh (2010), to simulate platoons of vehicles with traffic flow transference within segment cells to reduce simulation time. Secondly, based on the cellular automaton and microscopic lane changing principles in mixed traffic, proposed by Lan et al.(2009、2010), to simulate platoons of vehicles with parallel driving and lane changing behaviors in close proximity to the intersection. In order to make these two models stated above integrate properly, this study develops a macro-micro traffic flow models with a transmission interface design, which combines advantages over both models and takes characteristics of mixed traffic into consideration. Moreover, real data of mixed traffic on urban streets is collected. To obtain all the vehicle trajectories in the experimental segment and calculate numbers of vehicles in each cell at each time step through analyzing them. The proposed model in different scenarios is assumed and divided into seven kinds of macro-micro proportions. The efficiency index is measured by CPU time and accuracy index is by SMAPE values to validate the proposed model. This study puts emphasis on the simulation effectiveness of interfaces in different positions of the segment and tries to find out the best one. The results demonstrate that the macroscopic traffic flow models is conductive to reduce the simulation time and improve efficiency. The microscopic traffic flow models make for accuracy. Under a balanced of efficiency and accuracy, the best position of the interface measured by simulation effectiveness is thirty to sixty meters apart from the intersection. It is supposed to transfer the model from macroscopic to microscopic before the traffic flow is interrupted.

Research Doctorate - Doctor of Philosophy (PhD)
This thesis presents a control and modulation scheme for the Modular Multilevel Converter under unbalanced power conditions. The modular multilevel converter is a relatively new converter topology and since its introduction has garnered interest in both literature and industry for its applications in High Voltage DC transmission. Whilst the majority of the published work has been for traditional applications for the converter, there has been recent interest in new applications for the converter. This includes the use of the converter as a photovoltaic interface, where power sources are directly connected to each converter cell. To maintain operation under a variety of operating conditions, new control and modulation schemes may be required. The thesis presents an energy balancing model based on the production of a number of controlled circulating current components in the converter. This energy model allows for the decoupling of the power generation in each arm, resulting in independent control of the arm voltages, and the compensation for large unbalanced power production across the converter. A model based deadbeat current controller is developed to control the converters output and circulating currents. A new heuristic model predictive control based modulation scheme is proposed to allow for the operation of each converter cell at separate references while generating the desired arm voltages. This is achieved while providing a balance between switching transitions and the spread of cell voltages from their references in each converter arm. Simulation and experimental results are presented to validate the performance and functionality of the proposed control and modulation scheme. It was found that the control scheme provides for the ability to maintain stable converter operation with large varied powers across all converter cells while maintaining balanced output powers and low device switching frequencies.

碩士
國立交通大學
運輸與物流管理學系
104
Mixed traffic cell transmission model (MCTM) can efficiently combine cell transmission model (CTM) with the behaviors of mixed traffic consisting of cars and motorcycles. The MCTM is restricted by the limitation of the homogeneous cell, it cannot describe the discrepancy between each lane on urban roads. Based on this, this study proposes multi-lanes mixed traffic cell transmission model to describe the lane difference on urban roads. Because the lane difference can be classified by turn-movement and vehicle type, the multi-lanes mixed traffic cell transmission model treat each turn-movement and vehicle type as one unit from the upstream of the road. The model combines with macro lane-changing function while the traffic propagation, and does the traffic discharge by each lane at the downstream of the road. Based on the field observations, the lane-changing is affected by signal, density and the difference of density at the downstream; the lane-changing is affected by turn-movement and vehicle type at the upstream. To validate the proposed model, videotaped traffic data in Hsinchu city are collected. The results show that the gap between the real data and the simulated data are the error percentage of the travel time of each car is 28% and the error percentage of the travel time of each motorcycle is 28%.

碩士
國立成功大學
交通管理學系碩博士班
97
The Flow Theory can be divided into three categories- macroscopic, mesoscopic and microscopic model. The Cell Transmission Model (CTM) in this study can be attributed to the mesoscopic model. The roads in the CTM are divided equally into consecutive sections by the distance a car runs with free flow speed at unit time. CTM defines the cell as equal length section or homogeneous section of the roads. Controlling the flow on the roads by means of capacities set for the cell is the main feasure of CTM. Most studies related to CTM were conducted abroad and aimed on the flow of free way. On the contrary, the similar studies related to CTM conducted domestically are quite few, not to mention the study aimed on the flow of signalized network in the urban area and using real time flow data for validation. This research attempts to conduct a CTM simulation program using MATLAB. The related information such as car generation rate and split ratio, which simulation needed as input data are generated by the dynamic traffic assignment software- DynaTAIWAN. The SanMing Section Network of Kaohsiung City (consists of five intersections and five sets of signals along Jiuru second Road and Minzu road) is selected as target sample for validation. All the comparisons of validation are on the basis of the data, realistic flow volume at the intervals of 7 AM to 9 AM of 9 consecutive Thursday starting from January 2009, collected by the Vehicle Detectors (VD) installed in the SanMing Section Network by the Municipal Transportation Bureau of Kaohsiung City. Both MAPE, RMSE are chosen to be the measure criteria of the study. Neglecting the volume data collected on January 29th, the fourth day of Chinese Lunar New Year, which is abnormally low, most comparisons of validation, for the VD data from 8 out of 9 sample Thursdays, are between 20% and 50% based on MAPE and less than 50% based on RMSE, and perform a reasonable or almost excellent forecast. Furthermore, the excellent performance showed on March 5th and March 12th, the comparisons of validation of both days’ VD data are less than 30% based on MAPE. The outcomes resulted from both criteria show that CTM equals to reason on the volume of signalized network in the urban area of Taiwan.

碩士
國立宜蘭大學
電機工程學系碩士班
107
In recent years, urban transportation has developed rapidly, traffic congestion and traffic incidents under a limited road area have resulted in fuel consumption and increased human travel time. However, a lot of traffic congestion methods have been proposed. In this study, we propose two-level traffic congestion control strategies which according to the order of formation of traffic jams, are classified into three areas: A, B, and C to prevent traffic jams caused by accidents: (1) ban light is used to stop vehicles from driving in the direction of an accident, and (2) warning light is used to guide vehicles not to drive in the direction of an accident zone. In addition, we simulate a two-way traffic network by using CTM (Cell Transmission Model). In the road network simulation, we construct an 8 by 8 format traffic network model. All the vehicles entering the model are inferred from the distribution equation of the CTM in the road network, and all the routes in the road network are collected. Vehicle parameters include traffic density and congestion lane values. We also verify the effectiveness of our control strategy on the two-way traffic network. The simulation results show that are three key parameters can influence the traffic jams such as: the control strategy starting time, the rate of vehicle routes changed and the traffic density. Simulation results show our traffic congestion strategy is useful in urban traffic network systems.

碩士
逢甲大學
交通工程與管理所
97
For the increasing of the traffic volume, the freeway management needs to use real time traffic information to estimate the variations of the traffic flow and then solve the congestion in the freeway systems. Freeway systems need a good traffic flow model to calculate the most suitable ramp metering. We present the field data collected on National Freeway No.1, the section from Sanyi to Miaoli, and Changhua to Puyan. The data is reorganized to include 20 second interval and 556 meter cell-length. The occupancy of the vehicle detector data is extracted to be applied for the proposed model. Then, the occupancies are converted into the car-in- the-cell to satisfy the application for using CTM. The results show that the Mean Absolute Percentage Error (MAPE) of the CTM falls into a reasonable range. However, the errors of the MAPE are increased while the cells are located at on-ramp and off-ramp or the time is between 18 to 19. Furthermore, we use the CTM at meter control. We analyze the density while the Level of Service (LOS) is classified as A and B, and used them to calculate the on-ramp metering. Finally, we used TSIS to analyze the Measure of Effectiveness (MOE) for on-ramp meter. The results show that under moderate to high congested traffic flow, the CTM could accurately estimate vehicles at the on-ramp metering. And increase the on-ramp metering in the low traffic flow. We tested the on-ramps in Nantun and Changhua, and the testing results are in accordance with the simulation values.

碩士
國立成功大學
交通管理學系碩博士班
101
Traffic signal control has become the most important issue in urban traffic management. Traffic congestion occurs when pre-timed signal control could not meet the actual demand, such as inappropriate signal timing or discontinued phases in arterials. Adaptive signal control logic obtains traffic flow data from vehicle detectors. According to the traffic prediction model and control logic, adaptive control calculates optimal signal decisions which could reduce delay and stops. This research has developed three models from Taiwanese adaptive control logic called COMDYCS-3E, which includes turning proportion estimation model, traffic prediction with cell transmission model (CTM), and six steps timing decision process. We used Signal Control API from VISSIM software to establish adaptive signal control logic, and measured the performance by simulating in VISSIM environment. After the traffic experiment of urban arterial, results showed that the RMSE of turning proportion estimation model is about 0.07. And adaptive signal control logic improves more than 5% system delay against pre-timed and fully actuated signal control.

This dissertation investigates the development of new Global system for mobile communications (GSM) improvement algorithms used to solve the nondeterministic polynomial-time hard (NP-hard) problem of assigning cells to switches. The departure of this project from previous projects is in the area of the GSM network being optimised. Most previous projects tried minimising the signalling load on the network. The main aim in this project is to reduce the operational expenditure as much as possible while still adhering to network element constraints. This is achieved by generating new network configurations with a reduced transmission cost. Since assigning cells to switches in cellular mobile networks is a NP-hard problem, exact methods cannot be used to solve it for real-size networks. In this context, heuristic approaches, evolutionary search algorithms and clustering techniques can, however, be used. This dissertation presents a comprehensive and comparative study of the above-mentioned categories of search techniques adopted specifically for GSM network improvement. The evolutionary search technique evaluated is a genetic algorithm (GA) while the unsupervised learning technique is a Gaussian mixture model (GMM). A number of custom-developed heuristic search techniques with differing goals were also experimented with. The implementation of these algorithms was tested in order to measure the quality of the solutions. Results obtained confirmed the ability of the search techniques to produce network configurations with a reduced operational expenditure while still adhering to network element constraints. The best results found were using the Gaussian mixture model where savings of up to 17% were achieved. The heuristic searches produced promising results in the form of the characteristics they portray, for example, load-balancing. Due to the massive problem space and a suboptimal chromosome representation, the genetic algorithm struggled to find high quality viable solutions. The objective of reducing network cost was achieved by performing cell-to-switch optimisation taking traffic distributions, transmission costs and network element constraints into account. These criteria cannot be divorced from each other since they are all interdependent, omitting any one of them will lead to inefficient and infeasible configurations. Results obtained further indicated that the search space consists out of two components namely, traffic and transmission cost. When optimising, it is very important to consider both components simultaneously, if not, infeasible or suboptimum solutions are generated. It was also found that pre-processing has a major impact on the cluster-forming ability of the GMM. Depending on how the pre-processing technique is set up, it is possible to bias the cluster-formation process in such a way that either transmission cost savings or a reduction in inter base station controller/switching centre traffic volume is given preference. Two of the difficult questions to answer when performing network capacity expansions are where to install the remote base station controllers (BSCs) and how to alter the existing BSC boundaries to accommodate the new BSCs being introduced. Using the techniques developed in this dissertation, these questions can now be answered with confidence.
Dissertation (MEng)--University of Pretoria, 2008.
Electrical, Electronic and Computer Engineering
unrestricted

碩士
國立成功大學
交通管理科學系
102
This research is to develop an adaptive signal control logic under mixed traffic flow conditions. There are two objectives: (1) develop a traffic prediction model under mixed traffic flow condition which is proper to adaptive signal control logic, (2) Measure the performance of the adapative signal control logic. The traffic prediction model is called enchanced cell transmission model (enhanced CTM) developed by observing both real vehicle driving behavior and simulation result in VISSIM software. This model fits some traffic condition such as permissive motorcycle lane, motorcycle-stopping area, left-turn protect phase, and etc. The experiment result of this model shows the error either car or motorcycle flow in a certern place on the road in a two-second time interval is less than one unit. The adaptive signal control logic is constructed from the traffic prediction model this research developed, turning proportion estimate model, and six-step timing decision process under a structure from a Taiwanese adaptive signal control logic called COMDYCS-3E. The result experiment in VISSIM environment shows that the adaptive signal control logic has better performance compared with either pre-timed signal control or actuated control especially under a varied volume scenario. This research develop a traffic prediction model under mixed traffic flow condition with a well prediction ability. This model is also applied to an adaptive signal control logic, and the performance of signal control is better than other control method.

碩士
國立清華大學
化學工程學系
102
Creating a unidirectional electron transport is one of the key factors of reaching high power energy conversion efficiency in dye-sensitized solar cell. Unfortunately, undesired electron pathway called recombination exists in real devices. The recombination causes photocurrent loss and mainly occurs at TiO2/electrolyte as well as FTO/electrolyte interface. Herein we focus on retarding the recombination at latter interface by using Nb2O5 blocking layer. Owing to slightly higher conduction band position of Nb2O5 comparing to TiO2, which can suppress charge recombination and enhance power conversion efficiency. In this study, the Nb2O5 blocking layer was prepared by the spin coating 5mM niobium ethoxide ethanol solution on FTO substrate. The film was then characterized by X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS) and transmission electron microscopy (TEM), which indicated a small part of TT-phase crystalline was formed. The uniformity of such blocking layer was scrutinized by optical microscope (OM) and scanning electron microscope (SEM). UV/Vis spectroscope was used to determine the transmittance of so-prepared Nb2O5 thin film on FTO. Band structure was positioned by XPS and UV/Vis spectroscope. In order to evaluate the recombination extent, the electrochemical impedance spectroscopy with transmission line model was employed and the recombination resistance (Rct) can be obtained. At low forward bias, considering the same condition as low-sun irradiation, recombination takes place primarily at FTO/electrolyte interface. In the case of volatile electrolyte based devices, the Rct with the Nb2O5 blocking layer increases 3 times higher than the blank one. As non-volatile electrolyte was applied, more significant effect could be observed for 14 times improvement in Rct value in the device fabricated with this Nb2O5 blocking layer. As the result, the Nb2O5 blocking layer could suppress the recombination at FTO/electrolyte interface, especially under low-sun condition. An increase in power conversion efficiency from 11.1% to 11.8% and 7.87% to 8.53% were obtained in volatile and non-volatile electrolyte based devices, respectively. This research reveals the importance of blocking effect under low illumination, which is the crucial issue of indoor application for DSSC and this niobium oxide thin film acts as a remarkable blocking layer.

Indiana University-Purdue University Indianapolis (IUPUI)
Lithium-ion batteries are widely used for portable electronics due to high energy density, mature processing technology and reduced cost. However, their applications are somewhat limited by safety concerns. The lithium-ion battery users will take risks in burn or explosion which results from some internal components failure. So, a practical method is required urgently to find out the failures in early time. In this thesis, a new method based on temperature difference between internal point and surface (TDIS) of the battery is developed to detect the thermal failure especially the thermal runaway in early time. A lumped simple thermal model of a lithium-ion battery is developed based on TDIS. Heat transfer coefficients and heat capacity are determined from simultaneous measurements of the surface temperature and the internal temperature in cyclic constant current charging/discharging test. A look-up table of heating power in lithium ion battery is developed based on the lumped model and cyclic charging/discharging experimental results in normal operating condition. A failure detector is also built based on TDIS and reference heating power curve from the look-up table to detect aberrant heating power and bad parameters in transfer function of the lumped model. The TDIS method and TDIS detector is validated to be effective in thermal runaway detection in a thermal runway experiment. In the validation of thermal runway test, the system can find the abnormal heat generation before thermal runaway happens by detecting both abnormal heating power generation and parameter change in transfer function of thermal model of lithium ion batteries. The result of validation is compatible with the expectation of detector design. A simple and applicable detector is developed for lithium ion battery catastrophic failure detection.