Ray Tracing Complex Scenes on a Multiple-instruction Steam Multiple-Data Stream Concurrent Computer

The Ray Tracing technique generates perhaps the most realistic looking computergenerated images. It does so at the cost of a great deal of computer time. Many algorithms have been developed to speed up the ray tracing procedure, but it still remains the most CPU-intensive realistic image synthesis method. To date, ray tracing has remained largely in the realm of serial computers. The research in this thesis takes ray tracing strongly into the parallel computing domain and deals effectively with all of the central issuessurrounding the parallelization of this procedure. Results from the "Hypercube Ray Tracer" are collected and compared against other ray tracing systems. A new technique for ray tracing Constructive Solid Geometry objects is also developed and implemented.Electrical Engineerin

G-CSC Report 2010

The present report gives a short summary of the research of the Goethe Center for Scientific Computing (G-CSC) of the Goethe University Frankfurt. G-CSC aims at developing and applying methods and tools for modelling and numerical simulation of problems from empirical science and technology. In particular, fast solvers for partial differential equations (i.e. pde) such as robust, parallel, and adaptive multigrid methods and numerical methods for stochastic differential equations are developed. These methods are highly adanvced and allow to solve complex problems.. The G-CSC is organised in departments and interdisciplinary research groups. Departments are localised directly at the G-CSC, while the task of interdisciplinary research groups is to bridge disciplines and to bring scientists form different departments together. Currently, G-CSC consists of the department Simulation and Modelling and the interdisciplinary research group Computational Finance

Surface Remeshing and Applications

Due to the focus of popular graphic accelerators, triangle meshes remain the primary representation for 3D surfaces. They are the simplest form of interpolation between surface samples, which may have been acquired with a laser scanner, computed from a 3D scalar field resolved on a regular grid, or identified on slices of medical data. Typical methods for the generation of triangle meshes from raw data attempt to lose as less information as possible, so that the resulting surface models can be used in the widest range of scenarios. When such a general-purpose model has to be used in a particular application context, however, a pre-processing is often worth to be considered. In some cases, it is convenient to slightly modify the geometry and/or the connectivity of the mesh, so that further processing can take place more easily. Other applications may require the mesh to have a pre-defined structure, which is often different from the one of the original general-purpose mesh. The central focus of this thesis is the automatic remeshing of highly detailed surface triangulations. Besides a thorough discussion of state-of-the-art applications such as real-time rendering and simulation, new approaches are proposed which use remeshing for topological analysis, flexible mesh generation and 3D compression. Furthermore, innovative methods are introduced to post-process polygonal models in order to recover information which was lost, or hidden, by a prior remeshing process. Besides the technical contributions, this thesis aims at showing that surface remeshing is much more useful than it may seem at a first sight, as it represents a nearly fundamental step for making several applications feasible in practice

Research Reports: 1984 NASA/ASEE Summer Faculty Fellowship Program

A NASA/ASEE Summer Faulty Fellowship Program was conducted at the Marshall Space Flight Center (MSFC). The basic objectives of the programs are: (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA Centers. The Faculty Fellows spent ten weeks at MSFC engaged in a research project compatible with their interests and background and worked in collaboration with a NASA/MSFC colleague. This document is a compilation of Fellows' reports on their research during the summer of 1984. Topics covered include: (1) data base management; (2) computational fluid dynamics; (3) space debris; (4) X-ray gratings; (5) atomic oxygen exposure; (6) protective coatings for SSME; (7) cryogenics; (8) thermal analysis measurements; (9) solar wind modelling; and (10) binary systems

Particle Swarm Optimization

Particle swarm optimization (PSO) is a population based stochastic optimization technique influenced by the social behavior of bird flocking or fish schooling.PSO shares many similarities with evolutionary computation techniques such as Genetic Algorithms (GA). The system is initialized with a population of random solutions and searches for optima by updating generations. However, unlike GA, PSO has no evolution operators such as crossover and mutation. In PSO, the potential solutions, called particles, fly through the problem space by following the current optimum particles. This book represents the contributions of the top researchers in this field and will serve as a valuable tool for professionals in this interdisciplinary field

A new geometric-and-physics model of milling and an effective approach to medial axis transforms of free-form pockets for high performance machining

Mechanical part quality and productivity depend on many parameters in CNC milling processes, such as workpiece material, cutters, tool paths, feed rate, and spindle speed, etc. To pursue high performance machining, the cutting parameter optimization is in high demand in industry, though it is quite challenge. This innovative research successfully addresses some essential problems in optimizing the cutting parameters by developing a new geometric-and-physics integrated model of milling and proposing an effective approach to the medial axis transforms of free-form pockets. In this research, an original geometric model of 21/2- and 3-axis CNC milling is developed and integrated with a well-established mechanistic model. A main research contribution is that this integrated model can predict complex milling processes in higher fidelity with instantaneous material remove rates, cutting forces and spindle powers, compared to prior machining models. In the geometric model, an in-process workpiece model is introduced by using a group of discrete Z-layers and applying the B-Rep scheme to represent the workpiece shape on each layer, in order to accurately represent instantaneous cutter-and-workpiece engagement in 2Yz- and 3-axis milling. Hence, the un-deformed chip geometry can be found even for complex part milling, which is then fed to the mechanistic model to predict instantaneous cutting forces. By using this integrated model, cutting parameters can be optimized for profiling, pocketing, and surface milling to ensure steady cut and the maximum material removal rates. This model has been verified by experiments, and will be implemented into a software tool for Bombardier Aerospace. Another important research in this work is to propose aggressive roughing of free-form pockets for ultimately high cutting efficiency. For this purpose, an accurate, efficient approach to the medial axis transforms of free-form pockets and an optimal approach to multiple cutters selection and their path generation are proposed. The main contributions of this research include (1) a new mathematical model of medial axis point, (2) an innovative global optimization solver, the hybrid global optimization method, (3) an optimization model of selecting multiple cutters for the maximum material removal rate. This research can substantially promote aggressive roughing in the machining industry to increase cutting efficiency of free-form pockets. The technique has been validated using considerable number of cutting tests and can be directly implemented into commercial CAD/CAM softwar

13th Annual Review of Progress in Applied Computational Electromagnetics at the Naval Postgraduate School, Monterey, CA, March 17-21, 1997, Conference Proceedings Volumes I & II

Includes Volumes 1 &

Aeronautical engineering: A continuing bibliography with indexes (supplement 276)

This bibliography lists 705 reports, articles, and other documents introduced into the NASA scientific and technical information system in Feb. 1992. Subject coverage includes: design, construction, and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Development of novel electrical power distribution system state estimation and meter placement algorithms suitable for parallel processing

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThe increasing penetration of distributed generation, responsive loads and emerging smart metering technologies will continue the transformation of distribution systems from passive to active network conditions. In such active networks, State Estimation (SE) tools will be essential in order to enable extensive monitoring and enhanced control technologies. In future distribution management systems, the novel electrical power distribution system SE requires development in a scalable manner in order to accommodate small to massive size networks, be operable with limited real time measurements and a restricted time frame. Furthermore, a significant phase of new sensor deployment is inevitable to enable distribution system SE, since present-day distribution networks lack the required level of measurement and instrumentation. In the above context, the research presented in this thesis investigates five SE optimization solution methods with various case studies related to expected scenarios of future distribution networks to determine their suitability. Hachtel's Augmented Matrix method is proposed and developed as potential SE optimizer for distribution systems due to its potential performance characteristics with regard to accuracy and convergence. Differential Evolution Algorithm (DEA) and Overlapping Zone Approach (OZA) are investigated to achieve scalability of SE tools; followed by which the network division based OZA is proposed and developed. An OZA requiring additional measurements is also proposed to provide a feasible solution for voltage estimation at a reduced computation cost. Realising the requirement of additional measurements deployment to enable distribution system SE, the development of a novel meter placement algorithm that provides economical and feasible solutions is demonstrated. The algorithm is strongly focused on reducing the voltage estimation errors and is capable of reducing the error below desired threshold with limited measurements. The scalable SE solution and meter placement algorithm are applied on a multi-processor system in order to examine effective reduction of computation time. Significant improvement in computation time is observed in both cases by dividing the problem into smaller segments. However, it is important to note that enhanced network division reduces computation time further at the cost of accuracy of estimation. Different networks including both idealised (16, 77, 356 and 711 node UKGDS) and real (40 and 43 node EG) distribution network data are used as appropriate to the requirement of the applications throughout this thesis.‘High Performance Computing Technologies for Smart Distribution Network Operation' (HiPerDNO) project under Grant FP7 - 248135/2007-2013 (European Community's Seventh Framework Programme)