A new progressive lossy-to-lossless coding framework for 2.5-dimensional (2.5-D) triangle meshes with arbitrary connectivity is proposed by combining ideas from the previously proposed average-difference image-tree (ADIT) method and the Peng-Kuo (PK) method with several modifications. The proposed method represents the 2.5-D triangle mesh with a binary tree data structure, and codes the tree by a top-down traversal. The proposed framework contains several parameters. Many variations are tried in order to find a good choice for each parameter considering both the lossless and progressive coding performance. Based on extensive experimentation, we recommend a particular set of best choices to be used for these parameters, leading to the mesh-coding method proposed herein / Graduate

In large-scale distributed memory multiprocessors, communication latency scaleup is the bottleneck of the overall system performance. Router design is the major factor that affects system communication performance. On a medium level of communication workload, queuing delay due to congestion can drastically increase communication latency. In this research, we designed a router of a globally adaptive routing method. The routing method polls traffic states in the mesh interconnection network. Based on the polled traffic information, it performs congestion-reduction routing and improves communication latency on a medium level of communication workload. The method partitions a mesh into a hierarchical structure to facilitate traffic state polling and routing at various levels of routing regions. The method adopts two detailed routing methods : look-around routing and parallel approximate maze routing, in order to make congestion-avoidance routing decisions at corresponding levels of routing regions. In this research, we proposed a system design of its router design. In addition, we added a multicast routing function and a fault-tolerance capability into the system design. We utilized system simulation of its hardware architectonic to compare the congestion-reduction capabilities of the router design and other commonly used router designs such as the minimal router, and thin overall communication performance.

Computational analysis and design has become a fundamental part of product research, development, and manufacture in aerospace, automotive, and other industries. In general the success of the specific application depends heavily on the accuracy and consistency of the computational model used. The aim of this work is to reduce the time needed to prepare geometry for mesh generation. This will be accomplished by developing tools that semi-automatically repair discrete data. Providing a level of automation to the process of repairing large, complex problems in discrete data will significantly accelerate the grid generation process. The developed algorithms are meant to offer semi-automated solutions to complicated geometrical problems—specifically discrete mesh intersections and isolated boundaries. The intersection-repair strategy presented here focuses on repairing the intersection in-place as opposed to re-discretizing the intersecting geometries. Combining robust, efficient methods of detecting intersections and then repairing intersecting geometries in-place produces a significant improvement over techniques used in current literature. The result of this intersection process is a non-manifold, non-intersecting geometry that is free of duplicate and degenerate geometry. Results are presented showing the accuracy and consistency of the intersection repair tool. Isolated boundaries are a type of gap that current research does not address directly. They are defined by discrete boundary edges that are unable to be paired with nearby discrete boundary edges in order to fill the existing gap. In this research the method of repair seeks to fill the gap by extruding the isolated boundary along a defined vector so that it is topologically adjacent to a nearby surface. The outcome of the repair process is that the isolated boundaries no longer exist because the gap has been filled. Results are presented showing the precision of the edge projection and the advantage of edge splitting in the repair of isolated boundaries.

This thesis addresses the problem of relaxing a finite element mesh to more closely match a size function. The main contributions include new methods for performing size function based mesh relaxation, as well as an algorithm for measuring the performance of size function based mesh relaxation methods.

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Triangle meshes have been widely used in many fields such as digital archives, computer-assisted design and in the game industry. The topic we are particularly interested is triangle mesh compression for fossil models. This thesis explores the research area of triangle mesh compression and implements a good compressor for our data set. The compressor is mainly based on a previously proposed algorithm, Edgebreaker, with modifications and improvements. The details of the implementation and our improvements are described in detail in this thesis. / Thesis (Master, Computing) -- Queen's University, 2013-07-27 18:49:44.051

Two highly effective content-adaptive methods for generating Delaunay mesh models of images, known as IID1 and IID2, are proposed. The methods repeatedly alternate between mesh simplification and refinement, based on the incremental/decremental mesh-generation framework of Adams, which has several free parameters. The effect of different choices of the framework's free parameters is studied, and the results are used to derive two mesh-generation methods that differ in computational complexity. The higher complexity IID2 method generates mesh models of superior reconstruction quality, while the lower complexity IID1 method trades mesh quality in return for a decrease in computational cost. Some of the contributions of our work include the recommendation of a better choice for the growth-schedule parameter of the framework, as well as the use of Floyd-Steinberg error diffusion for the initial-mesh selection. As part of our work, we evaluated the performance of the proposed methods using a data set of 50 images varying in type (e.g., photographic, computer generated, and medical), size and bit depth with multiple target mesh densities ranging from 0.125% to 4%. The experimental results show that our proposed methods perform extremely well, yielding high-quality image approximations in terms of peak-signal-to-noise ratio (PSNR) and subjective visual quality, at an equivalent or lower computational cost compared to other well known approaches such as the ID1, ID2, and IDDT methods of Adams, and the greedy point removal (GPR) scheme of Demaret and Iske. More specifically, the IID2 method outperforms the GPR scheme in terms of mesh quality by 0.2-1.0 dB with a 62-93% decrease in computational cost. Furthermore, the IID2 method yields meshes of similar quality to the ID2 method at a computational cost that is lower by 9-41%. The IID1 method provides improvements in mesh quality in 93% of the test cases by margins of 0.04-1.31 dB compared to the IDDT scheme, while having a similar complexity. Moreover, reductions in execution time of 4-59% are achieved compared to the ID1 method in 86% of the test cases. / Graduate / 0544, 0984, 0537 / marzouki@uvic.ca

Wire mesh dampers are under investigation because they are seen as replacements for squeeze film dampers as a source of direct stiffness and damping at bearing locations. There are several advantages of wire mesh dampers over squeeze film dampers, including: temperature insensitivity, oil-free operation, and the ability to contain large amplitude vibrations. Furthermore, due to their direct damping and lack of cross-coupled stiffness, the wire mesh reduces the response to imbalance and increases the stability of the system. The objective of this research was to determine the properties of wire mesh dampers under large amplitude vibrations. Impact testing was first conducted on the wire mesh as a means of obtaining the large amplitudes that were of interest. Next, to verify the results, a second methodology was employed using shaker testing. It was found that both the stiffness and hysteretic damping decrease with increasing displacement. However, they both approached asymptotes around 2 mils of displacement, and further increases in displacement had significantly less effect on the properties. Once the results were verified to be consistent, equations were obtained to describe the response of the wire mesh dampers. These equations were then used to create a new design workbook, which would allow an engineer to determine the properties of wire mesh dampers under conditions that they might experience.

This thesis is concerned with the evolution of implicit or explicit surfaces. The first part of this thesis addresses three problems in fluid simulation: advection, thin film, and the volume error. First, we show that the back and forth error compensation and correction (BFECC) method can significantly reduce the dissipation and diffusion. Second, thin film is hard to simulate since it has highly complex liquid/gas interface that requires high memory and computational costs. We address this difficulties by using cell centered octree grid to reduce memory cost and a multigrid method to reduce computational cost. Third, the volume loss is an undesired side effect of the level set method. The known solution to this problem is the particle level set method, which is expensive and has small but accumulating volume error. We provide a solution that is computationally effective and can prevent volume loss without accumulation. The second part of this thesis is focused on filtering a triangle mesh to produce a mesh whose details are selectively reduced or amplified. We develop a mesh filter with a rational transfer function, which is a generalization from previously developed mesh filters. In addition, we show that the mesh filter parameters can be computed from the physical size of mesh feature.