Tai-Ma-Li Experimental Forest is located at Chinfeng Hsiang in Taitung Country, with the altitudes range from 350 m to 1450 m, and with the topical and subtopical climate. The author had set up 54 plots to investigate the composition of natural broadleaved forest. The vegetation data analyzed by detrended correspondence analysis(DCA) and two-way indicator species analysis(TWINSPAN) classified the sampling plots into four forest types: I. Machilus thunbergii¡ÐCastanopsis carlesii forest type. It was found 1040 m to 1430 m alt., and mainly at ridge or gentle slope. II. Machilus konishii¡ÐDysoxylum hongkongense forest type. It was found from 916 m to 1255 m alt., and mainly at steep slope or valley. III. Lagerstroemia subcostata¡ÐMachilus kusanoi forest type. It was found from 456 m to 860 m alt., and mainly at steep slope or valley. IV. Dendrocnide meyeniana¡ÐArdisia sieboldii forest type. It was found from 442 m to 803 m, and mainly at ridge or slope. The study results of correlations among environmental gradients and ordination axes indicated that the elevation, aspect and slope are the most important environmental factors affected the vegetation composition and distribution. Topographic position also has significant correlation with vegetation types.

Abstract Patterns of plant species composition and their relationships to environmental factors were investigated in Jhuokou River basin. 102, 20 ¡Ñ 20 m plots with woody stems ¡Ù1.0 cm diameter at breast height (DBH) data and 12 environmental variables were analysed by Two Way Indicator Species Analysis (TWINSPAN), Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) to classify the vegetation types and determine the significant environmental variables that affect the distribution of vegetation. Classification and regression tree (CART) were then used to perform vegetation classification tree based on these significant variables. The vegetation classification result showed that 102 sampling plots can be classified into 9 vegetation types : 1. Daphniphyllum hlaucescens subsp. oldhamii - Cyclobalanopsis morii vegetation type ; 2. Neolitsea acuminatissima - Cyclobalanopsis morii vegetation type ; 3. Adinandra formosana - Lithocarpus lepidocarpus - Machilus thunbergii vegetation type ; 4. Elaeocarpus japonicus - Castanopsis cuspidate - Machilus thunbergii vegetation type ; 5. Ardisia quinquegona - Tricalysia dubia - Beilschmiedia erythrophloia vegetation type ; 6. Schefflera octophylla - Helicia formosana - Beilschmiedia erythrophloia vegetation type ; 7. Castanopsis formosana - Mallotus paniculatus - Schefflera octophylla vegetation type ; 8. Cyclobalanopsis glauca - Glochidion rubrum - Sapindus mukorossii vegetation type ; 9. Champereia manillana - Kleinhovia hospita - Murraya vegetation type. DCA and CCA distinguished 8 significant environmental variables from 12 measured variables. Altitude and warmth index were the most important variables in 8 significant environmental variables, but were highly correlated. When used vegetation classification tree to predict the position of the reference vegetation alliance, average accuracy was 56.9 %. The results indicated that the current data was still insufficient to predict the vegetation type at alliances level with environmental variables.

Elevated deoxycholic acid (DCA) and mutations in the Adenomatous Polyposis Coli (APC) tumor suppressor gene have been associated with increased risk of colorectal cancer (CRC). Chronic inflammation has also been associated with increased risk of CRC. It is unclear if DCA mediates inflammation in the normal or transformed colonic mucosa. The status of APC was manipulated in human CRC cell lines to study the role of DCA mediated inflammation. The chemotactic cytokine, CXCL8, was used as a marker of inflammation. Addition of DCA to the HT29-parental cell line with mutant-APC increased the steady state mRNA and protein levels of CXCL8. Conversely, addition of DCA to the HT29-APC cell line with wild type-APC was protective for increased steady state RNA and protein levels of CXCL8. DCA activated transcription factors which had binding regions in the CXCL8 5’-promoter. To elucidate the mechanism of induction, the 5’-promoter of CXCL8 was investigated. DCA increased promoter-reporter activity of the CXCL8 gene in HT29-parental cell line but wild type-APC blocked this effect. Chromatin immunoprecipitation (ChIP) revealed that DCA activated transcription factors, AP-1 and NF-κB were bound to the 5’-promoter of CXCL8. The transcription factor, β-catenin, was also bound to the 5’-promoter of CXCL8. Phenotypic effects were measured. Increased CXCL8 lead to matrix metalloproteinase-2 (MMP-2) production and increased invasion by HT29-parental cells on laminin coated filters. The DCA-mediated invasion was blocked by antibody directed against CXCL8 and wild type- APC. Therefore DCA-mediated inflammation occurs in transformed colonic epithelium and increases the invasive phenotype of CRC cells by CXCL8.

The traditional design of printed circuit board assembly focuses on finding a set of parameter values (that characterizes the process), such that the desired circuit performance specifications are met. It is usually assumed that this set of values can be accurately realized when the circuit or the assembly is built. Unfortunately, this assumption is not realistic for assemblies produced in mass scale. Fluctuations in manufacturing processes cause defects in actual values of the parameters. This variability in design parameters, in turn, causes defects in the functionality of the assemblies. The ratio of the acceptable assemblies to total assemblies produced constitutes the yield of the assembly process. Assembly yields of area array packages are heavily dependent on design of the board as much as package and process parameters. The economics of IC technology is such that the maximization of yield rather than the optimization of performance has become the topic of prime importance. The projected value of yield has always been a factor for consideration in the advancement of Integrated Chip technology. Due to considerable reduction in the package size, minimum allowable tolerance and tight parameter variations, electronic assemblies have to be simulated, characterized and tested before translating them to a production facility. Also, since the defect levels are measured in parts per million, it is impractical to build millions of assemblies for the purpose of identifying the best parameter. A mathematical model that relates design parameters and their variability to assembly yield can help in the effective estimation of the yield. This research work led to the development of a mathematical model that can incorporate variability in the package, board and assembly related parameters and construction of an effective methodology to predict the assembly yield of area array packages. The assembly yield predictions of the model are based on the characteristics of input variables (whether they follow a normal, empirical or experimental distribution). By incorporating the tail portion of the parameter distribution (up to ±6 standard deviation on normal distribution), a higher level of accuracy in assembly yield prediction is achieved. An estimation of the interaction of parameters is obtained in terms of the expected number of defective joints and/or components and a degree of variability around this expected value. As an implementation of the mathematical model, a computer program is developed. The software is user friendly and prompts the user for information on the input variables, it predicts the yield as expected number of defective joints per million and expected number of defective components (assemblies) per million. The software can also be used to predict the number of defects for a user-specified number of components (less or more than one million assemblies). The area array assembly yield model can be used to determine the impact of process parameter variations on assembly yields. The model can also be used to assess the manufacturability of a new design, represent the capability of an assembly line for bench marking purposes, help modify designs for better yield, and to define the minimum acceptable manufacturability standards and tolerances for components, boards and designs. / Master of Science

La communication sans fil joue un rôle de plus en plus important dans de nombreux domaines. Un grand nombre d'applications sont exploitées tels que l'e-banking, l'e-commerce, les services médicaux,….Ainsi, la qualité de service (QoS), et la confidentialité d'information sur le réseau sans fil sont primordiales dans la conception du réseau sans fil. Dans le cadre de cette thèse, nous nous concentrons sur le développement des approches d'optimisation pour résoudre certains problèmes concernant les deux sujets suivants : la qualité de service et la sécurité de la couche physique. Nos méthodes sont basées sur la programmation DC (Difference of convex functions) et DCA (DC Algorithms) qui sont reconnues comme de puissants outils d'optimisation non convexes et non différentiables. Ces outils ont connu de grands succès au cours des deux dernières décennies dans la modélisation et la résolution de nombreux problèmes d'applications dans divers domaines de sciences appliquées. Outre les chapitres d'introduction et de conclusion, le contenu principal de cette thèse est divisé en quatre chapitres: Le chapitre 2 concerne la QoS dans les réseaux sans fil tandis que les trois chapitres suivants étudient la sécurité de la couche physique. Le chapitre 2 considère un critère de QoS qui consiste à assurer un service équitable entre les utilisateurs dans un réseau sans fil. Plus précisement, on doit s'assurer qu'aucun utilisateur ne souffre d'un mauvais rapport signal sur bruit (“signal to noise ratio (SNR)" en anglais). Le problème revient à maximiser le plus petit SNR. Il s'agit donc un problème d'optimisation DC général (minimisation d'une fonction DC sur un ensemble défini par des contraintes convexes et des contraintes DC). La programmation DC et DCA ont été développés pour résoudre ce problème. Tenant compte de la structure spécifique du problème, nous avons proposé une nouvelle décomposition DC qui était plus efficace que la précédente décomposition. Une méthode de résolution basée sur la programmation DC et DCA a été développée. De plus, nous avons prouvé la convergence de notre algorithme. L'objectif commun des trois chapitres suivants (Chapitre 3, 4, 5) est de garantir la sécurité de la couche physique d'un système de communication sans fil. Nous nous concentrons sur l'approche qui consiste à maximiser le taux de secret (“secrecy rate” en anglais). Trois diverses architectures du réseau sans fil utilisant différentes techniques coopératives pour la transmission sont considérées dans ces trois chapitres. Dans le chapitre 3, nous considérons un réseau point-à-point utilisant une technique coopérative de brouillage. Le chapitre 4 étudie un réseau de relais utilisant une combinaison de technique de formation de faisceau ("beamforming technique" en anglais) et de technique de relais coopératifs. Deux protocoles de technique de relais coopératifs, Amplifier-et-Transmettre (“Amplify-and-Forward (AF)'') et Décoder-et-Transmettre (“Decode-and-Forward (DF)'' en anglais), sont considérés. Dans le chapitre 3 et le chapitre 4, nous considérons qu'il y a seulement un espion (“eavesdropper" en anglais) dans le réseau tandis que le chapitre 5 est une extension du chapitre 4 où on peut avoir plusieurs espions. Tous ces problèmes sont des problèmes d'optimisation non-convexes qui peuvent être ensuite reformulés sous forme d'une programmation DC pour lesquels nous développons les méthodes efficaces et robustes basées sur la programmation DC et DCA. Dans les chapitres 3 et 4, nous reformulons les problèmes étudiés sous forme d'un programme DC standard (minimisation d'une fonction DC avec les contraintes convexes). La structure spécifique est bien exploitée afin de concevoir des schémas DCA standard efficaces où les sous-problèmes convexes de ces schémas sont résolus soit explicitement soit de manière peu coûteuse. Les problèmes d'optimisation dans le chapitre 5 sont reformulés comme les programmes DC généraux et les schémas [...] / Wireless communication plays an increasingly important role in many aspects of life. A lot of applications of wireless communication are exploited to serve people's life such as e-banking, e-commerce and medical service. Therefore, quality of service (QoS) as well as confidentiality and privacy of information over the wireless network are of leading interests in wireless network designs. In this dissertation, we focus on developing optimization techniques to address some problems in two topics: QoS and physical layer security. Our methods are relied on DC (Difference of Convex functions) programming and DCA (DC Algorithms) which are powerful, non-differentiable, non-convex optimization tools that have enjoyed great success over the last two decades in modelling and solving many application problems in various fields of applied science. Besides the introduction and conclusion chapters, the main content of the dissertation is divided into four chapters: the chapter 2 concerns QoS in wireless networks whereas the next three chapters tackle physical layer security. The chapter 2 discusses a criterion of QoS assessed by the minimum of signal-to-noise (SNR) ratios at receivers. The objective is to maximize the minimum SNR in order to ensure the fairness among users, avoid the case in which some users have to suffer from a very low SNR. We apply DC programming and DCA to solve the derived max-min fairness optimization problem. With the awareness that the efficiency of DCA heavily depends on the corresponding DC decomposition, we recast the considered problem as a general DC program (minimization of a DC function on a set defined by some convex constraints and some DC constraints) using a DC decomposition different from the existing one and design a general DCA scheme to handle that problem. The numerical results reveal the efficiency of our proposed DCA compared with the existing DCA and the other methods. In addition, we rigorously prove the convergence of the proposed general DCA scheme. The common objective of the next three chapters (Chapter 3,4,5) is to guarantee security at the physical layer of wireless communication systems based on maximizing their secrecy rate. Three different architectures of the wireless system using various cooperative techniques are considered in these three chapters. More specifically, a point-to-point wireless system including single eavesdropper and employing cooperative jamming technique is considered in the chapter 3. Chapter 4 is about a relay wireless system including single eavesdropper and using a combination of beamforming technique and cooperative relaying technique with two relaying protocols Amplify-and-Forward (AF) and Decode-and-Forward (DF). Chapter 5 concerns a more general relay wireless system than the chapter 4, in which multiple eavesdroppers are considered instead of single eavesdropper. The difference in architecture of wireless systems as well as in the utilized cooperative techniques result in three mathematically different optimization problems. The unified approach based on DC programming and DCA is proposed to deal with these problems. The special structures of the derived optimization problems in the chapter 3 and the chapter 4 are exploited and explored to design efficient standard DCA schemes in the sense that the convex subproblems in these schemes are solved either explicitly or in an inexpensive way. The max-min forms of the optimization problems in the chapter 5 are reformulated as the general DC programs with DC constraints and the general DCA schemes are developed to address these problems. The results obtained by DCA show the efficiency of our approach in comparison with the existing methods. The convergence of the proposed general DCA schemes is thoroughly shown

In recent years, there have been tremendous advances in wireless & mobile communications, including wireless radio techniques, networking protocols, and mobile devices. It is expected that different broadband wireless access technologies, e.g., WiFi (IEEE 802.11) and WiMAX (IEEE 802.16) will coexist in the future. In the meantime, multimedia applications have experienced an explosive growth with increasing user demands. Nowadays, people expect to receive high-speed video, audio, voice and web services even when being mobile. The key question that needs to be answered, then, is how do we ensure that users always have the "best" network performance with the "lowest" costs in such complicated situations? The latest IEEE 802.11n standards attains rates of more than 100 Mbps by introducing innovative enhancements at the PHY and MAC layer, e.g. MIMO and Frame Aggregation, respectively. However, in this thesis we demonstrate that frame aggregation's performance adheres due to the EDCA scheduler's priority mechanism and consequently resulting in the network's poor overall performance. Short waiting times for high priority flows into the aggregation queue resolves to poor channel utilization. A Delayed Channel Access algorithm was designed to intentionally postpone the channel access procedure so that the number of packets in a formed frame can be increased and so will the network's overall performance. However, in some cases, the DCA algorithm has a negative impact on the applications that utilize the TCP protocol, especially the when small TCP window sizes are engaged. So, the TCP process starts to refrain from sending data due to delayed acknowledgements and the overall throughput drops. In this thesis, we address the above issues by firstly demonstrating the potential performance benefits of frame aggregation over the next generation wireless networks. The efficiency and behaviour of frame aggregation within a single queue, are mathematically analysed with the aid of a M=G[a;b]=1=K model. Results show that a trade-off choice has to be taken into account over minimizing the waiting time or maximizing utilization. We also point out that there isn't an optimum batch collection rule which can be assumed as generally valid but individual cases have to be considered separately. Secondly, we demonstrate through extensive simulations that by introducing a method, the DCA algorithm, which dynamically determines and adapts batch collections based upon the traffic's characteristics, QoS requirements and server's maximum capacity, also improves e ciency. Thirdly, it is important to understand the behaviour of the TCP ows over the WLAN and the influence that DCA has over the degrading performance of the TCP protocol. We investigate the cause of the problem and provide the foundations of designing and implementing possible solutions. Fourthly, we introduce two innovative proposals, one amendment and one extension to the original DCA algorithm, called Adaptive DCA and Selective DCA, respectively. Both solutions have been implemented in OPNET and extensive simulation runs over a wide set of scenarios show their effectiveness over the network's overall performance, each in its own way.

Cette thèse développe les deux approches locales et globales basées sur la programmation DC et DCA pour l'optimisation combinatoire en variables mixtes 0-1 et leurs applications à la résolution de nombreux problèmes en planification opérationnelle. Plus particulièrement, cette thèse adresse à: l'amélioration de l'algorithme d'approximation extérieure basée sur DCA (appelé DCACUT) introduit par Nguyen V.V. et Le Thi pour la programmation linéaire en variables mixtes 0-1, les combinaisons des algorithmes globaux et DCA et l'étude numérique comparative de ces approches pour la programmation linéaire en variables mixtes 0-1, l'utilisation de DCA à la résolution de la programmation DC en variables mixtes 0-1 en utilisant la pénalité exacte, la mise en œuvre des algorithmes développés à la résolution des problèmes de grande taille en planification opérationnelle comme les problèmes dans le réseau de télécommunication sans fils, les problèmes d’ordonnancement ainsi que le problème d'affectation de tâches des véhicules aériens non pilotés ou bien le problème des tournées de véhicules dans une chaîne d'approvisionnement / This thesis develops two local and global approaches based on DC programming and DCA for mixed 0-1 combinatorial optimization and their applications to many problems in operational planning. More particularly, this thesis consists of: the improvement of the outer approximation algorithm based on DCA (called DCACUT) introduced by Nguyen V.V and Le Thi for mixed 0-1 linear programming, the combinations of global algorithms and DCA and the comparative numerical study of these approaches for mixed 0-1 linear programming, the use of DCA for solving mixed 0-1 programming via an exact penalty technique, the implementation of the algorithms developed for solving large scale problems in operational planning: two problems in wireless telecommunication network, two scheduling problems, an UAV task assignment problem and an inventory routing problem in supply chains

Three-dimensional integrated circuits (3D ICs) have been designed with the purpose of achieving higher communication speed by reducing the interconnect length between integrated circuits, and integrating heterogeneous functions into one single package, among other advantages. As a growing, new technology, researchers are still studying the different parameters that impact the overall lifetime of such packages in order to ensure the customer receives reliable end products. This study focused on the effect of four design parameters on the lifetime of the interconnects and, in particular, solder balls and through-silicon vias (TSVs). These parameters included TSV pitch, TSV diameter, underfill stiffness and underfill thickness. A three-dimensional finite element model of a 3D IC package was built in ANSYS to analyze the effect of these parameters under thermo-mechanical cyclic loading. The stresses and damage in the interconnects of the IC were evaluated using Coffin-Manson and the energy partitioning fatigue damage models. A three-level Taguchi design of experiment method was utilized to evaluate the effect of each parameter. Minitab software was used to assess the main effects of the selected design parameters. Locations of maximum stresses and possible damage initiation were discussed, and recommendations were made to the manufacturer for package optimization. Due to the very small scale of the interconnects, conducting mechanical tests and measuring strains in small microscopic scale material is very complicated and challenging; therefore, it is very difficult to validate finite element and analytical analysis of stress and strain in microelectronic devices. At the next step of this work, a new device and method were proposed to facilitate testing and strain measurements of material at microscopic scale. This new micro-electromechanical system (MEMS) consisted of two piezoelectric members that were constrained by a rigid frame and that sandwiched the test material. These two piezoelectric members act as load cell and strain measurement sensors. As the voltage is applied to the first member, it induces a force to the specimen and deforms it, which in turn deforms the second piezoelectric member. The second piezoelectric member induces an output voltage that is proportional to its deformation. Therefore, the strain and stresses in the test material can be determined by knowing the mechanical characteristics of the piezoelectric members. Advantages of the proposed system include ease of use, particularly at microscopic scale, adaptability to measure the strain of different materials, and flexibility to measure the modulus of elasticity for an unknown material. An analytical analysis of the device and method was presented, and the finite element simulation of the device was accomplished. The results were compared and discussed. An inelastic specimen was also analyzed and sensitivity of the device to detecting nonlinear behavior was evaluated. A characteristic curve was developed for the specific geometry and piezoelectric material.

For the mass demands of personalized security services, such as tracking, supervision, and emergent rescue, the location technologies of mobile communication have drawn much attention of the governments, academia, and industries around the world. However, existing location methods cannot satisfy the requirements of low cost and high accuracy. We hypothesized that a new mobile location algorithm based on the current GSM system will effectively improve user satisfaction. In this study, a prototype system will be developed, implemented, and experimented by integrating the useful information such as the geometry of the cell layout, and the related mobile positioning technologies. The intersection of the regions formed by the communication space of the base stations will be explored. Furthermore, the density-based clustering algorithm (DCA) and GA-based algorithm will be designed to analyze the intersection region and estimate the most possible location of a mobile phone. Simulation results show that the location error of the GA-based is less than 0.075 km for 67% of the time, and less than 0.15 km for 95% of the time. The results of the experiments satisfy the location accuracy demand of E-911.

El objetivo que ha motivado esta tesis ha sido el analizar y proponer mecanismos para incrementar la capacidad de tráfico de un sistema de acceso radio DECT (Digital Enhanced Cordless Telecommunications) en entornos de exteriores, particularmente en los servicios de bucle de abonado vía radio y CTM (Cordless Terminal Mobility).El DECT fue diseñado en un principio para trabajar en entornos de interiores con alta capacidad de tráfico y calidad de voz comparable a un teléfono con hilos. Sin embargo, cuando el sistema debe operar en exteriores las condiciones de propagación cambian radicalmente y no se consiguen los mismos rendimientos que en interiores.Dentro de edificios se aprovechan las atenuaciones de paredes, techos y otros objetos para tener un gran reuso de los canales, el principal problema que presentan los escenarios de exteriores es que las señales interferentes se propagan con mucha más facilidad y la interferencia generada por el propio sistema limita su capacidad.En la tesis se presentan cuatro tipos de resultados analizados mediante un simulador software. El primer grupo está enfocado a incrementar la capacidad del sistema de bucle de abonado vía radio utilizando antenas directivas, control de potencia, arrays adaptativos y la posibilidad de que las estaciones base transmitan información de cuales son sus canales menos interferidos.El segundo tipo de resultados evalúa las prestaciones de la aplicación de CTM con usuarios móviles y diferentes posiciones de las estaciones base. El tercer tipo analiza técnicas que maximizan la eficiencia de los recursos más que la capacidad de tráfico, se han utilizado repetidores y antenas distribuidas. El último grupo de resultados examina al sistema de bucle de abonado en condiciones adversas de tráfico no uniforme y con dos operadores trabajando en la misma zona sin estar sincronizados.