Lau Shek Kwan Mark. / "September 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 118-124). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

In this thesis we study two important issues in vector optimization problem (VOP). The first is on the scalarization; here we provide some merit functions for VOP and analyze their error bound property. The second is on generalization of Ekeland's variational principle; here this famous result in variational analysis is now extended from the original setting for scalar-valued functions to that of vector-valued functions. This generalization enable us to study the error bound property for systems of functions instead of that for a single function. / Liu Chun-guang. / "June 2006." / Adviser: Kung-fu Ng. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6440. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 92-94). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Fu Peilin. / "February 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 149-157). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

by Yong Liang. / "November 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 237-266). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Cheung, Ho Yee. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 91-96). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Background --- p.5 / Chapter 2.1 --- Matroids and Matrices --- p.5 / Chapter 2.1.1 --- Examples --- p.6 / Chapter 2.1.2 --- Constructions --- p.7 / Chapter 2.1.3 --- Matroid Intersection --- p.8 / Chapter 2.1.4 --- Matroid Parity --- p.9 / Chapter 2.2 --- Matrix Formulations --- p.14 / Chapter 2.2.1 --- Graph Matching --- p.15 / Chapter 2.2.2 --- Skew-Symmetric Matrix --- p.16 / Chapter 2.2.3 --- Linear Matroid Parity --- p.21 / Chapter 2.2.4 --- Weighted Problems --- p.25 / Chapter 2.3 --- Algebraic Tools --- p.26 / Chapter 2.3.1 --- Matrix Algorithms --- p.26 / Chapter 2.3.2 --- Computing Matrix Inverse --- p.28 / Chapter 2.3.3 --- Matrix of Indeterminates --- p.32 / Chapter 2.3.4 --- Mixed Skew-symmetric Matrix --- p.34 / Chapter 2.4 --- Algebraic Algorithms for Graph Matching --- p.35 / Chapter 2.4.1 --- Matching in O{nw+1) time --- p.36 / Chapter 2.4.2 --- Matching in O(n3) time --- p.37 / Chapter 2.4.3 --- Matching in O(nw) time --- p.38 / Chapter 2.4.4 --- Weighted Algorithms --- p.39 / Chapter 2.4.5 --- Parallel Algorithms --- p.40 / Chapter 2.5 --- Algebraic Algorithms for Graph Connectivity --- p.41 / Chapter 2.5.1 --- Previous Approach --- p.41 / Chapter 2.5.2 --- Matrix Formulation Using Network Coding --- p.42 / Chapter 3 --- Linear Matroid Parity --- p.49 / Chapter 3.1 --- Introduction --- p.49 / Chapter 3.1.1 --- Problem Formulation and Previous Work --- p.50 / Chapter 3.1.2 --- Our Results --- p.52 / Chapter 3.1.3 --- Techniques --- p.55 / Chapter 3.2 --- Preliminaries --- p.56 / Chapter 3.3 --- A Simple Algebraic Algorithm for Linear Matroid Parity --- p.56 / Chapter 3.3.1 --- An 0(mr2) Algorithm --- p.56 / Chapter 3.4 --- Graph Algorithms --- p.59 / Chapter 3.4.1 --- Mader's S-Path --- p.59 / Chapter 3.4.2 --- Graphic Matroid Parity --- p.64 / Chapter 3.4.3 --- Colorful Spanning Tree --- p.66 / Chapter 3.5 --- Weighted Linear Matroid Parity --- p.69 / Chapter 3.6 --- A Faster Linear Matroid Parity Algorithm --- p.71 / Chapter 3.6.1 --- Matrix Formulation --- p.71 / Chapter 3.6.2 --- An O(mw) Algorithm --- p.74 / Chapter 3.6.3 --- An O(mrw - 1 ) Algorithm --- p.76 / Chapter 3.7 --- Maximum Cardinality Matroid Parity --- p.79 / Chapter 3.8 --- Open Problems --- p.80 / Chapter 4 --- Graph Connectivities --- p.81 / Chapter 4.1 --- Introduction --- p.81 / Chapter 4.2 --- Inverse of Well-Separable Matrix --- p.83 / Chapter 4.3 --- Directed Graphs with Good Separators --- p.86 / Chapter 4.4 --- Open Problems --- p.89

Les réseaux ad hoc diffèrent des réseaux filaires par la multitude de perturbation auxquels ils sont sujets. Alors qu’une rupture de lien est un événement plutôt rare sur des réseaux filaires, et généralement imputable à l’état physique du matériel intermédiaire, cet événement est courant avec les communications radio. Ceci est lié à la qualité du signal reçu de l’autre extrémité ou à la configuration de l’environnement. Les perturbations causées par l’environnement ne mènent pas seulement à une rupture d’un lien, elles peuvent avoir un impact sur la réception des données. La volatilité des liens est typique dans les réseaux sans fil alors pour les réseaux filaires ce problème est inexistant. TCP, qui est prévu pour assurer la transmission fiable des données, n’a été conçu qu’en tenant compte des contraintes des réseaux filaires. Ainsi, certains événements dans la transmission de données sans fil peuvent être mal interprétés et engendrer une mauvaise réaction de TCP. Pour améliorer la performance de TCP dans les réseaux ad hoc, l’objectif de cette thèse est double. Dans un premier temps, une étude complète des performances de TCP dans les réseaux ad hoc est dressée. Celle-ci concerne à la fois les débits atteignables et aussi la consommation d’énergie induite par l’utilisation de ce protocole de transport dans un réseau ad hoc. Cette étude permet d’identifier les points d’amélioration de TCP pour qu’il soit utilisable dans les réseaux ad hoc. Dans un second temps, nous proposons une nouvelle variante de TCP, appelée TCP-WELCOME, dont l’objectif est de traiter de façon adéquate les différents types de perte de paquets sur un réseau ad hoc et optimiser la performance de TCP. / Wireless ad hoc networks are different from wired networks by the multitude of data packet loss situations they are subjected to. This is due to the characteristics of wireless channel that might obstruct the proper reception of data packet at the destination end. In some case, these vulnerabilities of wireless channel can result in a complete link failure. Although link failure is of low probability in wired networks, it is rather common in wireless networks. The volatility of communication channel is a typical problem with wireless links, which is not the case with wired cables. TCP is a transport protocol that aims at ensuring high reliability and guarantying reception of data packets. However, TCP was designed for wired networks to address congestion, which is the main cause for data packet loss in wired networks. Therefore, other types of data packet loss encountered in wireless networks are prone to misinterpretation by TCP, which will lead to TCP performance degradation within the network. To overcome the performance limitation of TCP when used within ad hoc networks, the aim of this thesis is twofold. First, a complete performance study of TCP over ad hoc networks is achieved. This evaluation concerns two performance metrics: the achievable throughput and the energy consumption of TCP within ad hoc networks. This study allows identifying the potential room of improvement to enhance TCP efficiency in ad hoc networks. Second, we propose a new TCP variant, TCP-WELCOME that optimizes the performance of TCP in ad hoc networks through its ability to distinguish among, and efficiently deal with, different data packet loss situations, within ad hoc networks.

Missions concerning small-body celestial objects are of growing interest due to the resources and information they can provide. Such missions require detailed information about the surface of the body for interactions, such as landing on the surface, as well as predicting the gravity field of the object. This work provides a means of optimizing the mission elements of trajectory and imaging target schedules so that the level of knowledge of the surface can be increased. The information required to increase one's knowledge of the surface is described as a set of conditions placed on the collection of images taken of each facet of the surface; these requirements constitute the concept of "coverage" and were provided by NASA. Currently, no comparable optimization capability exists. The trajectory optimization task is done using an adapted form of the Non-dominated Sorting Genetic Algorithm-2 (NSGA-2) in which the genetic mutation and recombination operators are replaced with operators inspired by a different Evolutionary Algorithm, Differential Evolution. Since small-body objects have irregular distributions of mass, this optimization accounts for this by using a higher fidelity gravity model; the expense of the calculation causing a significant increase in fitness evaluation time. The trajectory optimization uses the maximization of possible coverage (the coverage achieved is every surface element were targeted for imaging at every opportunity) and minimization of a time quantity that typifies covering less but doing so quickly as the primary optimization objectives with an additional ancillary objective which rewards the fulfillment of the individual aspects of coverage so as to better condition improvement in the first objective. The optimization of imaging schedules is handled using a less adapted version of NSGA-2 in which the base operations were only tailored slightly. This differs from the previous task in that limitation are placed on the imaging process; namely that the camera may only target a single surface element at each opportunity and is thus only able to observe the faces caught within the narrow field-of-view. This optimization trades the minimization of time objective and the ancillary objective for the minimization of the required rotational effort of the imaging spacecraft. Both works result in sets of solutions to their respective problems that capture the trade-space between the considered objectives. The last work detailed here examines the consequences of how velocity domains are phrased in space trajectory optimization problems. Multiple means of framing the optimization domain are examined and the results detail the complications encountered by the more common formulations for a set of test problems.

No description available.

<p>This thesis considers several different techniques for optimizing Monte Carlo simulations. The Monte Carlo system used is Penelope but most of the techniques are applicable to other systems. The two mayor techniques are the usage of the graphics card to do geometry calculations, and raytracing. Using graphics card provides a very efficient way to do fast ray and triangle intersections. Raytracing provides an approximation of Monte Carlo simulation but is much faster to perform. A program was also written in order to have a platform for Monte Carlo simulations where the different techniques were implemented and tested. The program also provides an overview of the simulation setup, were the user can easily verify that everything has been setup correctly. The thesis also covers an attempt to rewrite Penelope from FORTAN to C. The new version is significantly faster and can be used on more systems. A distribution package was also added to the new Penelope version. Since Monte Carlo simulations are easily distributed, running this type of simulations on ten computers yields ten times the speedup. Combining the different techniques in the platform provides an easy to use and at the same time efficient way of performing Monte Carlo simulations.</p>

A simple but effective evolutionary algorithm is proposed in this paper for solving complicated optimization problems. The new algorithm presents two hybridization operations incorporated with the conventional genetic algorithm. It takes only 4.1% ~ 4.7% number of function evaluations required by the conventional genetic algorithm to obtain global optima for the benchmark functions tested. Application example is also provided to demonstrate its effectiveness. / Singapore-MIT Alliance (SMA)