因為今天四通八達的無線通信網絡對高速高質量通信的要求,加之無線通信資源的稀缺,使得資源分配在無線通信領域的地位越發的重要.多種多樣的無線通信資源和不同的設計要永使得資源分配問題變得很複雜,我們也很難找到一個通用的方法去解決所有的資源分配問題.在本文中, 我們研究一些典型的資源分配問題,通過最優化設計,給出恰當的高效的算法予以解決.本文中將會涉及集中化算法和分佈式算法。 / 在本文中, 我們首先研究協作通信中的功率分配和中繼選擇問題。這個問題因為其問題的組合性而變得很複雜。為了保證系統的性能並且同時避免過量的冗餘信息, 我們提出了一個新的概念"中繼選擇自由度"。更重要的是, 為了使我們的方法能夠適用於集中信息很難的大型通信系統, 我們提出了分佈式的解決方案。該方法在實際中可以比較簡單的實現。 / 我們接著研究多用戶接入網絡的"軟"服務質量控制問題。我們這裡考慮的情形是:用戶們有各自的服務質量要求, 比如有一個目標速率。因為系統的資源總是有限的, 如果有過多用戶, 那麼同時滿足所有用戶的服務質量要求有時候是不可能的。我們的目標是在這種情況發生的時候,優化整個系統的資源分配。我們提出了分佈式算法來解決這一個問題。 / 最後, 我們研究下行鏈中的波束成形問題。這裡我們出於實際情況考慮,系統中存在兩種用戶:優先用戶和非優先用戶。我們想要盡可能最大化的提升非優先用戶的性能,同時必須首先滿足優先用戶的服務質量用要求。我們這裡用不同的波束成形向量來完成這個任務。這個問題是NP問題,我們做了必要的一些放鬆處理來得到有效的較優的解。 / Due to the limited resources and high performance requirements in today’s wireless networks, optimization methods in resource allocation play a significant role in reaping the benefits from wireless communications. Various available resources and different design goals make the resource allocation problem complex and we are unlikely to find a generic approach for all problems. Thus in this thesis, we investigate several resource allocation problems and propose the proper optimization methods and algorithms that can efficiently give us desired solutions. Also, both centralized and distributed methods will be shown in this thesis. / We first study the joint power allocation and relay selection problem in cooperative communication. This problem is complex due to its combinatorial nature. In order to avoid high information overhead and system complexity while at the same time maintain system performance, we introduce a new concept called “relay selection degree bound“. Moreover, since in large scale cooperative communication network, collecting information and centralized control would be very difficult, we resort to distributed algorithms that can be easily implemented in practice. / We further consider the soft QoS control problem in multiple access network. Here we consider the situation where the users have quality of service(QoS) requirements, i.e., each user has a target rate for its application. Since the resources in the system are limited, these requirements will result in the infeasibility of the whole system if there are too many users. We aim at optimizing the performance of the whole system while this kind of infeasibility happens. We will see how distributed algorithms can work for this problem and give us desired results. / We finally consider the downlink beamforming problem where there are two kind of users in the system: priority users and non-priority users. We maximize the non-priority users performance while at the same time satisfying the priority users’ QoS requirements first. Here we adopt heterogeneous beamforming scheme to complete the task. Since the problem is NP hard, relaxation is done for efficient solutions. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Fang, Haoran. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 76-81). / Abstracts also in Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Background --- p.3 / Chapter 1.2.1 --- Wireless Communication Schemes --- p.3 / Chapter 1.2.2 --- Mathematical Preliminaries --- p.9 / Chapter 1.3 --- Outline of the Thesis --- p.11 / Chapter 2 --- Resource Allocation for Cooperative Communication Networks --- p.13 / Chapter 2.1 --- Chapter Introduction --- p.13 / Chapter 2.2 --- system model and problem formulation --- p.16 / Chapter 2.3 --- optimal power allocation scheme for arbitrary configuration --- p.20 / Chapter 2.4 --- Relay selection in the MAC layer --- p.24 / Chapter 2.4.1 --- Algorithm Design --- p.24 / Chapter 2.4.2 --- Distributed Implementation of The Relay Selection Algorithm --- p.29 / Chapter 2.5 --- Numerical Results --- p.33 / Chapter 2.5.1 --- The Convergence of Distributed Power Allocation Algorithm --- p.33 / Chapter 2.5.2 --- Performance of The Overall Cross Layer Solution --- p.34 / Chapter 2.5.3 --- Improvements of Heuristic Markov algorithm --- p.36 / Chapter 2.6 --- Chapter Conclusions --- p.38 / Chapter 3 --- Soft QoS Control in Multiple Access Network --- p.39 / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- system model --- p.41 / Chapter 3.3 --- Feasibility check and soft QoS control --- p.43 / Chapter 3.3.1 --- Feasibility Check --- p.43 / Chapter 3.3.2 --- Soft QoS Control --- p.45 / Chapter 3.3.3 --- Distributed Soft QoS Control --- p.47 / Chapter 3.3.4 --- Numerical Results --- p.53 / Chapter 3.4 --- Chapter Conclusion --- p.57 / Chapter 4 --- Heterogeneous resource allocation via downlink beamforming --- p.58 / Chapter 4.1 --- Introduction --- p.58 / Chapter 4.2 --- system model --- p.60 / Chapter 4.3 --- heterogeneous resource allocation via beamforming --- p.62 / Chapter 4.3.1 --- Relaxation and problem analysis --- p.62 / Chapter 4.3.2 --- Randomization for final solutions --- p.66 / Chapter 4.4 --- Numerical Results --- p.69 / Chapter 4.5 --- Conclusion --- p.70 / Chapter 5 --- Conclusions and Future Work --- p.73 / Chapter 5.1 --- Conclusions --- p.73 / Chapter 5.2 --- Future Work --- p.74 / Bibliography --- p.76

Yuan, Yan. / Thesis submitted in: November 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 84-87). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Wireless Mesh Network --- p.3 / Chapter 1.1.1 --- Architecture Overview --- p.3 / Chapter 1.1.2 --- Routing Protocols --- p.5 / Chapter 1.2 --- Contribution of this Thesis --- p.7 / Chapter 1.3 --- Organization of this Thesis --- p.8 / Chapter 2 --- Background and Literature Review --- p.9 / Chapter 2.1 --- VoIP on Wireless Mesh Networks --- p.9 / Chapter 2.1.1 --- Performance of VoIP on Wireless Mesh Networks --- p.9 / Chapter 2.1.2 --- Optimizations for VoIP over Wireless Mesh Networks --- p.12 / Chapter 2.1.3 --- Path and Packet Aggregation Scheme --- p.14 / Chapter 2.2 --- Network Coding on Wireless Mesh Networks --- p.15 / Chapter 2.2.1 --- The Concept of Network Coding --- p.15 / Chapter 2.2.2 --- Related Work --- p.16 / Chapter 3 --- Adaptive Path and Packet Aggregation System --- p.19 / Chapter 3.1 --- Overview --- p.19 / Chapter 3.2 --- The Adaptive Path Aggregation Routing Algorithm --- p.20 / Chapter 3.2.1 --- Protocol Overview --- p.20 / Chapter 3.2.2 --- Data Structure --- p.21 / Chapter 3.2.3 --- The Concept of Link Weight and Path Weight --- p.26 / Chapter 3.2.4 --- APA Operations --- p.27 / Chapter 3.3 --- The Packet Aggregation System --- p.39 / Chapter 3.3.1 --- Overview --- p.39 / Chapter 3.3.2 --- Packet structure --- p.40 / Chapter 3.3.3 --- Local Compression --- p.41 / Chapter 3.3.4 --- Packet Aggregation/Disaggregation --- p.42 / Chapter 3.4 --- Performance Analysis --- p.44 / Chapter 3.4.1 --- Integration of the path aggregation routing protocol and the packet aggregation system --- p.46 / Chapter 3.5 --- Performance Evaluation --- p.48 / Chapter 3.5.1 --- Testbed Setup --- p.48 / Chapter 3.5.2 --- Packet aggregation --- p.48 / Chapter 3.5.3 --- Combined scenario: path and packet aggregation --- p.58 / Chapter 3.6 --- Summary --- p.65 / Chapter 4 --- Network Coding System in wireless network --- p.67 / Chapter 4.1 --- Overview --- p.67 / Chapter 4.2 --- System Architecture --- p.68 / Chapter 4.2.1 --- Packet Format --- p.68 / Chapter 4.2.2 --- Encoding and decoding --- p.69 / Chapter 4.3 --- Performance Evaluation --- p.71 / Chapter 4.3.1 --- Experiment Setup --- p.71 / Chapter 4.3.2 --- Performance Metric --- p.72 / Chapter 4.3.3 --- Experiment Results --- p.72 / Chapter 4.4 --- Summary --- p.79 / Chapter 5 --- Conclusions and Future Directions --- p.82

Micromanufacturing consists of processes for producing structures, devices or systems with feature sizes measured in micrometers. Micromanufacturing began in the mid-1960's with microelectronics fabrication technology. In the 1980's, Micro-Electro-Mechanical Systems (MEMS) began to be developed, in which electrical and mechanical subsystems were integrated at small scales. More recently, Microtechnology-based Energy and Chemical Systems (MECS) have been developed that have led to improved heat and mass transfer in energy and chemical systems. At Oregon State University, new methods to fabricate MECS have been developed. One of the new methods involves microlamination--bonding thin strips of different materials together. This method has generated a high volume and low-cost approach to the production of high-aspect-ratio (height-to-width) structures. Past efforts to make microfloat valves using microlamination methods resulted in an 11:1 diodicity ratio. It was hypothesized that the valve had a ridge of redeposited material around the valve seat caused by the condensation and deposition of ablation ejecta during laser machining. The contribution of this thesis is the creation of a microfloat valve using an Electrochemical Micromachining (EMM) method. EMM methods are known to produce smooth surfaces, free of burrs or any other types of aspirates. Therefore, it was hypothesized that float valves made with EMM methods would improve valve performance. Four steps were involved in the creation of the microfloat valve: lamina formation, laminae registration, laminae bonding and component dissociation. A total of 9 laminae-some of which were made with 304 stainless steel 76.2 ��m thick, others of which were made with 50.8 ��m thick polyimide-made up the microfloat valve. Photolithography and EMM were used to form the lamina. Even though the laminae created by EMM were smaller in size than desired, the machined areas did not have redeposited material, and some areas had straight walls. In laminae registration, a two edge registration method was used. In the laminae bonding step, laminae were bonded by the adhesive method at 248��C under 135 kPa pressure for 13.5 minutes. In the component dissociation step, a capacitor dissociation method that was designed at OSU was used. Upon performance testing, the average diodicity ratio for the EMM valve was 12.45 over the range 0 kPa-450 kPa, indicating improved performance when compared to the Laser Ablation valve-which had an average 11.17 over the range 0 kPa-100 kPa. Microscope examination of valves revealed that statistically significant improvement in valve performance would require refinement of component dissociation methods. / Graduation date: 2000

Since the dawn of the computer age, there has been a push to create miniature devices. These devices were initially integrated circuit (IC) devices to perform calculations for computers. As the technology progressed, the scope of the devices diverged to included microelectromechanical (MEMS) devices, meaning that the devices perform mechanical movements via electrical actuation. More recently, a new generation of devices has evolved called microtechnology-based energy and chemical systems (MECS). MECS may employ MEMS technology, however the systems are not designed to produce only mechanical movement. MECS deal with heat and mass transfer, the basic processes used in energy, chemical and biological systems, in the mesoscale realm. Mesoscale devices range from the size of a sugar cube to the size of a human fist. The possibilities of MECS have not been realized. Heating and cooling systems, chemical mixing/distribution, and locking systems are all potential applications. The devices require: 1) revolutionary design, accounting for the scaling effects on device performance; 2) new fabrication technologies for the creation of these designs; and 3) good material properties for mechanical and chemical interactions. Fabrication requirements for MECS are different than for MEMS in that MECS generally require non-silicon metals. Metal microlamination (MML) has been introduced as a general practice for meeting the fabrication requirements for MECS. Prior MML fabrication methods have emphasized the use of diffusion bonding, soldering, or brazing techniques. This thesis will introduce: 1) a novel microflapper valve design fabricated in mild steel using a novel microprojection welding technique; 2) a novel microfloat valve design fabricated in mild steel using a novel capacitive dissociation process for creating free floating geometries. The devices are characterized by comparing actual flow rates to theoretical flow rates of equivalent orifice sizes. Preliminary results show that the microfloat valve achieved an average diodicity (free flow versus leakage rate) ratio of 11.19, while the microflapper valve achieved an average diodicity ratio of 4.08. The theoretical orifice sizes of the microfloat and microflapper valves are 0.629 mm and 0.611 mm respectively. These results suggest that the float valve is the superior design. / Graduation date: 1999

Multi-core machines have become common and have led to an increase in multithreaded software. In turn, the number of concurrency bugs has also increased. Such bugs are elusive and remain difficult to solve, despite existing research. Thus, this thesis proposes a system which detects, prevents and optionally helps expose concurrency bugs. Specifically, we focus on bugs caused by atomicity violations, which occur when thread interleaving violates the programmer’s assumption that a code section executes atomically. At compile-time, our system performs static analysis to identify code sections where violations could occur. At run-time, we use debug registers to monitor these sections for interleaving thread accesses which would cause a violation. If detected, we undo their effects and thus prevent the violation. Optionally, we help expose atomicity violations by perturbing thread scheduling during execution. Our results demonstrate that the system is effective and imposes low overhead.

Multi-core machines have become common and have led to an increase in multithreaded software. In turn, the number of concurrency bugs has also increased. Such bugs are elusive and remain difficult to solve, despite existing research. Thus, this thesis proposes a system which detects, prevents and optionally helps expose concurrency bugs. Specifically, we focus on bugs caused by atomicity violations, which occur when thread interleaving violates the programmer’s assumption that a code section executes atomically. At compile-time, our system performs static analysis to identify code sections where violations could occur. At run-time, we use debug registers to monitor these sections for interleaving thread accesses which would cause a violation. If detected, we undo their effects and thus prevent the violation. Optionally, we help expose atomicity violations by perturbing thread scheduling during execution. Our results demonstrate that the system is effective and imposes low overhead.

While some attempts have been made to model the behaviour of the grand piano action (the mechanism that translates a key press into a hammer striking a string), most researchers have reduced the system to a simple model with little relation to the components of a real action. While such models are useful for certain applications, they are not appropriate as design tools for piano makers, since the model parameters have little physical meaning and must be calibrated from the behaviour of a real action. A new model for a piano action is proposed in this thesis. The model treats each of the five main action components (key, whippen, jack, repetition lever, and hammer) as a rigid body. The action model also incorporates a contact model to determine the normal and friction forces at 13 locations between each of the contacting bodies. All parameters in the model are directly measured from the physical properties of individual action components, allowing the model to be used as a prototyping tool for actions that have not yet been built. To test whether the model can accurately predict the behaviour of a piano action, an experimental apparatus was built. Based around a keyboard from a Boston grand piano, the apparatus uses an electric motor to actuate the key, a load cell to measure applied force, and optical encoders and a high speed video camera to measure the positions of the bodies. The apparatus was found to produce highly repeatable, reliable measurements of the action. The behaviour of the action model was compared to the measurements from the experimental apparatus for several types of key blows from a pianist. A qualitative comparison showed that the model could very accurately reproduce the behaviour of a real action for high force blows. When the forces were lower, the behaviour of the action model was still reasonable, but some discrepancy from the experimental results could be seen. In order to reduce the discrepancy, it was recommended that certain improvements could be made to the action model. Rigid bodies, most importantly the key and hammer, should be replaced with flexible bodies. The normal contact model should be modified to account for the speed-independent behaviour of felt compression. Felt bushings that are modelled as perfect revolute joints should instead be modelled as flexible contact surfaces.

The goal of an automatic speech recognition system is to enable the computer in understanding human speech and act accordingly. In order to realize this goal, language modeling plays an important role. It works as a knowledge source through mimicking human comprehension mechanism in understanding the language. Among many other approaches, statistical language modeling technique is widely used in automatic speech recognition systems. However, the generation of reliable and robust statistical model is very difficult task, especially for a large vocabulary system. For a large vocabulary system, the performance of such a language model degrades as the vocabulary size increases. Hence, the performance of the speech recognition system also degrades due to the increased complexity and mutual confusion among the candidate words in the language model. In order to solve these problems, reduction of language model size as well as minimization of mutual confusion between words are required. In our work, we have employed clustering techniques, using self-organizing map, to build topical language models. Moreover, in order to capture the inherent semantics of sentences, a lexical dictionary, WordNet has been used in the clustering process. This thesis work focuses on various aspects of clustering, language model generation, extraction of task dependent acoustic parameters, and their implementations under the framework of the CMU Sphinx3 speech engine decoder. The preliminary results, presented in this thesis show the effectiveness of the topical language models.

Iris recognition systems capture an image from an individual's eye. The iris in the image is then segmented and normalized for feature extraction process. The performance of iris recognition systems highly depends on segmentation and normalization. For instance, even an effective feature extraction method would not be able to obtain useful information from an iris image that is not segmented or normalized properly. This thesis is to enhance the performance of segmentation and normalization processes in iris recognition systems to increase the overall accuracy. <br /><br /> The previous iris segmentation approaches assume that the boundary of pupil is a circle. However, according to our observation, circle cannot model this boundary accurately. To improve the quality of segmentation, a novel active contour is proposed to detect the irregular boundary of pupil. The method can successfully detect all the pupil boundaries in the CASIA database and increase the recognition accuracy. <br /><br /> Most previous normalization approaches employ polar coordinate system to transform iris. Transforming iris into polar coordinates requires a reference point as the polar origin. Since pupil and limbus are generally non-concentric, there are two natural choices, pupil center and limbus center. However, their performance differences have not been investigated so far. We also propose a reference point, which is the virtual center of a pupil with radius equal to zero. We refer this point as the linearly-guessed center. The experiments demonstrate that the linearly-guessed center provides much better recognition accuracy. <br /><br /> In addition to evaluating the pupil and limbus centers and proposing a new reference point for normalization, we reformulate the normalization problem as a minimization problem. The advantage of this formulation is that it is not restricted by the circular assumption used in the reference point approaches. The experimental results demonstrate that the proposed method performs better than the reference point approaches. <br /><br /> In addition, previous normalization approaches are based on transforming iris texture into a fixed-size rectangular block. In fact, the shape and size of normalized iris have not been investigated in details. In this thesis, we study the size parameter of traditional approaches and propose a dynamic normalization scheme, which transforms an iris based on radii of pupil and limbus. The experimental results demonstrate that the dynamic normalization scheme performs better than the previous approaches.

Hexplorer is a six-legged walking robot developed at the University of Waterloo. The robot is controlled by a network of seven digital signal processors, six of which control three motors each, for a total of 18 motors. Brand new custom electronics were designed to house the digital signal processors and associated circuitry. A variable duty factor wave gait, developed by Yoneda et al. was simulated and implemented on the robot. Simulation required an in-depth kinematic analysis that was complicated by the mechanical design of parallel mechanism comprising the legs. These complications were handled in both simulation and implementation. However, due to mechanical issues Hexplorer walked for only one or two steps at a time.