No description available.

Remotely operated vehicle (ROV) dynamics is affected by hydrodynamic forces such as added mass and viscous drag force. Both of added mass and drag force coefficients can be measured by a set of Planar Motion Mechanism (PMM) tests; however, it is costly. In this study, an economic method for identifying hydrodynamic parameters of ROV is given. A simplified nonlinear ROV dynamics model with twelve unknown hydrodynamic parameters in six degrees of freedom was derived for simulations. The identification is based on experimental data obtained by projective mapping method which is utilized to measure the planar motions of a ROV. Then least-squares optimization is performed by comparison between the theoretical simulations and the actual motion measurements. But, an optimization computation involving a large number of parameters is likely to get trapped in a local minimum. Therefore, to reduce the number of parameters to be optimized, some models of simple motions such as surge, sway, surge and sway, yaw, and heave are decoupled from the ROV dynamic model. A commercial ROV ¡§Seamor¡¨ that equipped with two vertical thrusters, two horizontal thrusters, and a depth sensor is used for identification. The experiments for measuring ROV motions of surge, sway, surge and sway, and yaw were performed in a swimming pool in National Sun Yat-sen University. A video camera is utilized to capture ROV for position estimation using projective mapping method. As for the heave motion of ROV, the experiment was conducted offshore the Shio-Liu-Qiu Island and the ROV depth was measured by an onboard pressure sensor. Then, optimal hydrodynamic parameters are identified in sequence of surge, heave, yaw, sway, and then surge and sway. Verification experiments were performed and the simulation results with the optimum values of hydrodynamic parameters show good agreement with the measured data from verification experiments.

This thesis proposes novel, efficient execution-paradigms for parallel heterogeneous architectures. The end of Dennard scaling is threatening the effectiveness of DVFS in future nodes; therefore, new execution paradigms are required to exploit the non-linear relationship between performance and energy efficiency of memory-bound application-regions. To attack this problem, we propose the decoupled access-execute (DAE) paradigm. DAE transforms regions of interest (at program-level) in two coarse-grain phases: the access-phase and the execute-phase, which we can independently DVFS. The access-phase is intended to prefetch the data in the cache, and is therefore expected to be predominantly memory-bound, while the execute-phase runs immediately after the access-phase (that has warmed-up the cache) and is therefore expected to be compute-bound. DAE, achieves good energy savings (on average 25% lower EDP) without performance degradation, as opposed to other DVFS techniques. Furthermore, DAE increases the memory level parallelism (MLP) of memory-bound regions, which results in performance improvements of memory-bound applications. To automatically transform application-regions to DAE, we propose compiler techniques to automatically generate and incorporate the access-phase(s) in the application. Our work targets affine, non-affine, and even complex, general-purpose codes. Furthermore, we explore the benefits of software multi-versioning to optimize DAE in dynamic environments, and handle codes with statically unknown access-phase overheads. In general, applications automatically-transformed to DAE by our compiler, maintain (or even exceed in some cases) the good performance and energy efficiency of manually-optimized DAE codes. Finally, to ease the programming environment of heterogeneous systems (with integrated GPUs), we propose a novel system-architecture that provides unified virtual memory with low overhead. The underlying insight behind our work is that existing data-parallel programming models are a good fit for relaxed memory consistency models (e.g., the heterogeneous race-free model). This allows us to simplify the coherency protocol between the CPU – GPU, as well as the GPU memory management unit. On average, we achieve 45% speedup and 45% lower EDP over the corresponding SC implementation.

A limited and extendable master thesis is representing the first step in the experimental substructuring of an A600 wind turbine. Additional masses have been designed, manufactured and added to the sub components for the laboratory experimental tests. Further preparations for dynamic experimental tests have been described and implemented. Vibrational tests of a modified wind turbine blade have been made using the Leuven Measurements System (LMS) for excitations and data acquisition purposes. The theory of frequency response function based substructuring applied on the wind turbine blade model is demonstrated. The theory and an example of a Matlab coded spring-mass system, an experimental model of a wind turbine blade and FRFs stemming from measurements are reported.

The rapidly increasing number of cores available in multicore processors does not necessarily lead directly to a commensurate increase in performance: programs written in conventional languages, such as C, need careful restructuring, preferably automatically, before the benefits can be observed in improved run-times. Even then, much depends upon the intrinsic capacity of the original program for concurrent execution. Using software techniques to parallelize the sequential application can raise the level of gain from multicore systems. Parallel programming is not an easy job for the user, who has to deal with many issues such as dependencies, synchronization, load balancing, and race conditions. For this reason the role of automatically parallelizing compilers and techniques for the extraction of several threads from single-threaded programs, without programmer intervention, is becoming more important and may help to deliver better utilization of modern hardware. One parallelizing technique that has been shown to be an effective for the parallelization of applications that have irregular control flow and complex memory access patterns is Decoupled Software Pipeline (DSWP). This transformation partitions the loop body into a set of stages, ensuring that critical path dependencies are kept local to a stage. Each stage becomes a thread and data is passed between threads using inter-core communication. The success of DSWP depends on being able to extract the relatively fine-grain parallelism that is present in many applications. Another technique which offers potential gains in parallelizing general purpose applications is slicing. Program slicing transforms large programs into several smaller ones that execute independently, each consisting of only statements relevant to the computation of certain, socalled, (program) points. This dissertation explores the possibility of performance benefits arising from a secondary transformation of DSWP stages by slicing. To that end a new combination method called DSWP/Slice is presented. Our observation is that individual DSWP stages can be parallelized by slicing, leading to an improvement in performance of the longest duration DSWP stages. In particular, this approach can be applicable in cases where DOALL is not. In consequence better load balancing can be achieved between the DSWP stages. Moreover, we introduce an automatic implementation of the combination method using Low Level Virtual Machine (LLVM) compiler framework. This combination is particularly effective when the whole long stage comprises a function body. More than one slice extracted from a function body can speed up its execution time and also increases the scalability of DSWP. An evaluation of this technique on six programs with a range of dependence patterns leads to considerable performance gains on a core-i7 870 machine with 4-cores/8-threads. The results are obtained from an automatic implementation that shows the proposed method can give a factor of up to 1.8 speed up compared with the original sequential code.

Parallel manipulators have been the subject of study of much robotic research during the past three decades. A parallel manipulator typically consists of a moving platform that is connected to a fixed base by at least two kinematic chains in parallel. Parallel manipulators can provide several attractive advantages over their serial counterpart in terms of high stiffness, high accuracy, and low inertia, which enable them to become viable alternatives for wide applications. But parallel manipulators also have some disadvantages, such as complex forward kinematics, small workspace, complicated structures, and a high cost. To overcome the above shortcomings, progress on the development of parallel manipulators with less than 6-DOF has been accelerated. However, most of presented parallel manipulators have coupled motion between the position and orientation of the end-effector. Therefore, the kinematic model is complex and the manipulator is difficult to control. Only recently, research on parallel manipulators with less than six degrees of freedom has been leaning toward the decoupling of the position and orientation of the end-effector, and this has really interested scientists in the area of parallel robotics. Kinematic decoupling for a parallel manipulator is that one motion of the up-platform only corresponds to input of one leg or one group of legs. And the input cannot produce other motions. Nevertheless, to date, the number of real applications of decoupled motion actuated parallel manipulators is still quite limited. This is partially because effective development strategies of such types of closed-loop structures are not so obvious. In addition, it is very difficult to design mechanisms with complete decoupling, but it is possible for fewer DOF parallel manipulators. To realize kinematic decoupling, the parallel manipulators are needed to possess special structures; therefore, investigating a parallel manipulator with decoupling motion remains a challenging task. This thesis deals with lower mobility parallel manipulator with decoupled motions. A novel parallel manipulator is proposed in this thesis. The manipulator consists of a moving platform that is connecting to a fixed base by three legs. Each leg is made of one C (cylinder), one R (revolute) and one U (universal) joints. The mobility of the manipulator and structure of the inactive joint are analyzed. Kinematics of the manipulator including inverse and forward kinematics, velocity equation, kinematic singularities, and stiffness are studied. The workspace of the parallel manipulator is examined. A design optimization is conducted with the prescribed workspace. It has been found that due to the special arrangement of the legs and joints, this parallel manipulator performs three translational degrees of freedom with decoupled motions, and is fully isotropic. This advantage has great potential for machine tools and Coordinate Measuring Machine (CMM). / UOIT

Enhancing the quality of services in the distribution system is an important topic for power system research. It is imperative to employ precise network modeling and effective simulation tools, and a good system model is the key. This dissertation starts with modifying the building algorithms of Y-admittance and Z-impedance matrices. The Y-matrix will be built according to phase sequences. With the facts that the line self-impedance is significantly greater than the mutual-coupling terms and the existence of a high r/x ratio in distribution, two decoupled load flow methods (Phase-Decoupled¡BPD and Sub-Phase-Decoupled¡BSPD) with Current Injection Model(CIM) were developed. A new Z-matrix building algorithm was also developed in this dissertation. It decomposed the traditional Z into two sub-matrices, the upper and lower triangular matrices respectively. The matrices represent the relationships between the branch current and the bus injection current, and between the bus voltage and the branch current. Enhancing the quality of services will be effectively achieved by a proper capacitor placement technique. This dissertation develops a linear relationships of voltage changes versus the capacitor compensation, the branch current changes versus the capacitor compensation, and loss reductions versus the capacitor compensation. For loss reduction, a linear optimization function was defined to solve the capacitor placement problem. Tests have shown that the proposed methods were suitable for applications to an unbalance distribution system.

[pt] Dia a dia, técnicas mais avançadas são citadas e utilizadas na análise de sistemas de potência. Os métodos de resolução de fluxo de potência têm merecido especial atenção na medida em que são utilizados em diversos estudos. Programas digitais têm sido elaborados especialmente para cada determinada aplicação prática, onde são definidas as necessidades de rapidez de convergência, de requisitos de memória e de confiabilidade da solução, fatores que quase sempre são interdependentes. A introdução de algoritmos de ajuste convencionais e automáticos da solução de um fluxo de potência em um método moderno chamado Rápido desacoplado é o objeto de estudo do presente trabalho. São analisados os seguintes controles: Tensão na barra primária de um transformador com variação de taps sob condições de carga; fluxo de potência ativa entre áreas do sistema; geração de reativos em barras de tensão controlada; tensão em barras de carga; tensão em barras de carga remotas (sem geração de reativos). Para o bom entendimento da necessidade de se escolher o algoritmo adequado, para cada tipo de aplicação prática, são apresentados conceitos de condicionamento, ordenação e fatorização triangular da matriz representativa do sistema de potência em análise. / [en] Today we can see more and more advanced tecniques being used in the power system analysis. Researchers have been giving more attention to the power flow solution methods because they are used in various studies. Specific digital programes have been elaborated for each pratical application, when the necessities of the convergence rate, memory requests and the confiability of the solutions are defined. In the majority of cases, these factors are interdependent. The topic of this paper is the introduction of conventional and authomatic algorithms for adjusted solutions of pawer flow in a modern methos namad Fast Decoupled. The following controls are analysed: Load-Tap-Changing-Tranformer; Phase-Shifter; Area Interchange Control; Reactive Constraints; Voltage Constraints in PQ-Bus and remote-Bus. Concepts of consition, ordenation and trangular factorization of the power system representative matrix are showed in order to emphasize the necessity of selection of the most convenient algorthm for each practical application.

With the advances in very large scale integration (VLSI) technology, hundreds of billions of transistors can be packed into a single chip. With the increased hardware budget, how to take advantage of available hardware resources becomes an important research area. Some researchers have shifted from control flow Von-Neumann architecture back to dataflow architecture again in order to explore scalable architectures leading to multi-core systems with several hundreds of processing elements. In this dissertation, I address how the performance of modern processing systems can be improved, while attempting to reduce hardware complexity and energy consumptions. My research described here tackles both central processing unit (CPU) performance and memory subsystem performance. More specifically I will describe my research related to the design of an innovative decoupled multithreaded architecture that can be used in multi-core processor implementations. I also address how memory management functions can be off-loaded from processing pipelines to further improve system performance and eliminate cache pollution caused by runtime management functions.

This thesis investigated if decoupled design of the air intake and exhaust systems for four-stroke internal combustion engines is possible. Using the information found design guidelines were set up for the formula student team ELiTH Racing. The literature study revealed that the systems are not uncoupled, and the inuence of exhaust geometry on air intake behavior needed more thorough investigation. Experiments were designed, using a single cylinder engine with simple intake and exhaust geometries. The tests were attempted, but had to be abandoned due to time constraints. Successful tests would have yielded results in the form of pressure measurements, froma Prandtl-tube, in the air intake, and footage of smoke tests. As a secondary task the potential of computer simulations during the design process was investigated, which yielded a suggestion on how to set up a complete reasonable computational model of the systems. This also resulted in that the design guidelines included how to use computer simulations for the design process. Finally a few ways to expand this work are presented.