Estruturas de dados (ED) topológicas oferecem diversas vantagens quando se deseja executarumadeformação sobreumamalha. Essas EDs permitem movimentar os nós da malha sem modificar sua topologia, são relativamente simples de seremimplementadas e também são passíveis de serem incorporadas a um ciclo simulação/deformação de forma completamente automática e eficiente. O primeiro objetivo deste trabalho é a concepção de uma ED topológica para representação de malhas elásticas. Tais malhas podem ser do tipo superficial ou volumétrica, e ainda simples ou mista. Para melhor desempenho, confiabilidade e menor consumo de memória, deseja-se que a ED seja implícita quanto à representação de componentes incidentes e adjacentes dos elementos presentes na malha. Outro objetivo deste trabalho é abordar o problema de geração de malhas em domínios arbitrários definidos por uma função implícita. O método proposto é uma extensão do algoritmo de Partição da Unidade Implícita (PUI). Para isso, o método proposto é baseado numa abordagem de preenchimento de superfícies. Este método proposto gera adaptativamente tetraedros em diferentes níveis de refinamento de acordo com o nível de detalhe presente na região do domínio. Diferentemente de trabalhos anteriores, esta característica é feita naturalmente sem necessitar de uma estrutura auxiliar. Para este fim, usa-se uma estrutura algébrica chamada de triangulação Ja1 que é capaz de lidar com tais refinamentos. Além do mais, a triangulação Ja1 permite que se percorra a estrutura simplesmente através de regras algébricas que é uma outra vantagem do método proposto / Topological data Structures (DS) oer several advantages when performing a deformation on a mesh. These DSs allow movement throughout the mesh without modifying its topology, are relatively simple to implement, and there is always the possibility of merging it to simulation/deformation cycle on a completely automatic and ecient form. The main goal of this work is to design and implement a topological DS to represent elastic meshes. These meshes can be either of surface or volume kind, and even simple or mixed. For better performance, more reliability and lower memory consumption, it is necessary that the DSs allow the representation of incident and adjacent components of a given element to be implicit. The second objective to this work is to tackle the problem of mesh generation on arbitrary domains defined by implicit functions. The proposed method is an extension to the algorithm of Partition of Unity Implicits (PUI). For this the proposed method is based on an isosurface stung approach. It adaptively generates the tetrahedra in dierent levels of refinement accordingly to the level of detail presented by the regions of the domain. Dierently to previous work, this feature is done naturally without the aid of an auxiliary data structure. To this end, we use an algebraic structure, named Ja1 triangulation, which is capable of dealing with such refinements. In addition, the Ja1 triangulation permits traversing through the mesh by simply using algebraic rules which is another advantage to the proposed method

Submitted by Verena Pereira (verenagoncalves@uefs.br) on 2018-11-14T23:32:15Z No. of bitstreams: 1 Disserta??o - Dados Astron?micos_Uma proposta de implementa??o para banco de dados - VERSAO DIGITAL.pdf: 12472772 bytes, checksum: 7819133722c393f66647cb47f14700c6 (MD5) / Made available in DSpace on 2018-11-14T23:32:15Z (GMT). No. of bitstreams: 1 Disserta??o - Dados Astron?micos_Uma proposta de implementa??o para banco de dados - VERSAO DIGITAL.pdf: 12472772 bytes, checksum: 7819133722c393f66647cb47f14700c6 (MD5) Previous issue date: 2018-06-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / With the advent of computing, the way of doing science has changed circumstantially, revolutionizing scientific research. In astronomy, telescopes now equipped with increasingly modern sensors, produce data quantities never seen before, making it impossible to exhaust all the capacity to extract knowledge from the data produced, thus presenting conditions of reuse by their peers or other purposes. The value of this data to Science lies in its unexplored potential. In this sense, this work shares the philosophy of Virtual Observatories, regarding the reuse of old data. Therefore, this dissertation is about the implementation of procedures and computational techniques that allow to organize and search for images from telescopes. Images that were found were of the exclusive period. With this, studies were developed on data structure, computational tools, algorithms and programming languages that could contribute to the development and resolution of the research problem under analysis / Com advento da Computa??o, a forma de fazer Ci?ncia mudou circunstancialmente, revolucionando a pesquisa cient?fica. Na Astronomia, os telesc?pios agora equipados com sensorescada vez mais modernos, produzem quantidades de dados nunca vista antes, tornando imposs?vel exaurir toda ? capacidade de extra??o de conhecimento dos dados produzidos, apresentando assim, condi??es de reutiliza??o pelos seus pares ou outras finalidades. O valor desses dados para a Ci?ncia est? no seu potencial n?o explorado. Nesse sentido, esse trabalho compartilha da filosofia dos Observat?rios Virtuais,no que tange ? reutiliza??o de dados antigos. Para tanto, essa disserta??o versa sobre a implementa??o de procedimentos e t?cnicas computacionais que permitem organizar e buscar imagens oriundas de telesc?pios. Imagens que se encontram foram do per?odo de exclusividade. Com isso, foram desenvolvidos estudos sobre estrutura de dados, ferramentas computacionais, algoritmos e linguagens de programa??o que pudessem contribuir com o desenvolvimento e resolu??o do problema de pesquisa em an?lise

[pt] Diversas aplicações, em matemática, computação gráfica, medicina, geofísica e outras áreas, têm explorado a representação de sólidos por superfícies de contorno, em particular malhas poligonais. As malhas podem aproximar com muita precisão as propriedades geométricas da superfície de contorno de um sólido e ainda guardar importantes propriedades topológicas das superfícies como gênero, bordo e conexidade. Devido à grande complexidade dessas malhas, elas são geralmente processadas em meios computacionais usando alguma estrutura de dados. Essas estruturas guardam, além da geometria da malha, informações de incidências e adjacências entre os elementos da malha e exigem uma capacidade de armazenamento e processamento em função da complexidade da malha. Apesar da evolução dos recursos computacionais disponíveis para a manipulação destas estruturas, malhas extremamente complexas com milhões de elementos inviabilizam o armazenamento, processamento e transmissão de sua estrutura de dados nos meios computacionais. Muitas pesquisas recentes estão voltadas para a obtenção de processos de simplificação de malhas que permitam representar a mesma superfície com menos elementos na estrutura de dados e processos de compressão que codifiquem os modelos em formatos menores para efeitos de transmissão e armazenamento em mídia. Neste trabalho, desenvolvemos operadores, em uma estrutura de dados compacta, para a simplificação de malhas através da decimação de células da superfície. Objetivamos, com esses operadores, obter uma malha menos complexa que preserve as propriedades topológicas da superfície original e ainda, controlar as propriedades geométricas como volume, área e aspecto visual da mesma. Apresentamos ainda algumas aplicações para os processos de simplificação desenvolvidos com esses operadores. / [en] Many applications, in mathematics, computer graphics, medical imaging, geophysics and others, have used the representation of solids by their boundary surface, usually polygonal meshes. Those meshes can represent, with high precision, the geometric properties of the boundary surface of solid and also store important topological surface properties as genus, boundary and connected components. Because of the high complexity of such meshes, they are usually processed by the computers using specific data structures. These structures store, beyond the mesh geometry, information about incidence and adjacency relations among the mesh elements. They require computational resources for storage and processing according to the mesh complexity. Even with the development of the computational resources available for handling such structures, very large meshes with millions of elements are hard to store, to process and to exchange through the web. Many recent researches are looking for mesh simplification process that allows to represent the same surface with fewer elements and compression process to encode it in compact ways for transmition and storage. In this work, we develop topological operators, in a concise data structure, for simplifying meshes by the decimation of its cells. One of our goals, with these operators, is to obtain a mesh with a low complexity that preserves the topological properties from the original surface without loosing the control of the geometric proprieties as volume, area and visual aspect.

The modern day tourists do not want to deal with the hassle of using a large number of travel guides and paper maps while travelling. They would prefer to be able to access required information via their mobile phones or Personal Digital Assistants (PDAs). We realise that the delivered information may be originally available in numerous information formats. To support the administrator of the tourist guides the programme is required to help sorting information from these different sources and to help inserting them into a system. Our goal with this project is to develop a software support for processing information import via a graphical user interface, to support the administrator in identifying and extracting the appropriate sight information from various resources. The interface also helps in transferring and storing the structured and unstructured data into the TIP database.

Many digital models used in entertainment, medical visualization, material science, architecture, Geographic Information Systems (GIS), and mechanical Computer Aided Design (CAD) are defined in terms of their boundaries. These boundaries are often approximated using triangle meshes. The complexity of models, which can be measured by triangle count, increases rapidly with the precision of scanning technologies and with the need for higher resolution. An increase in mesh complexity results in an increase of storage requirement, which in turn increases the frequency of disk access or cache misses during mesh processing, and hence decreases performance. For example, in a test application involving a mesh with 55 million triangles in a machine with 4GB of memory versus a machine with 1GB of memory, performance decreases by a factor of about 6000 because of memory thrashing. To help reduce memory thrashing, we focus on decreasing the average storage requirement per triangle measured in 32-bit integer references per triangle (rpt). This thesis covers compact connectivity representation for triangle meshes and discusses four data structures: 1. Sorted Opposite Table (SOT), which uses 3 rpt and has been extended to support tetrahedral meshes. 2. Sorted Quad (SQuad), which uses about 2 rpt and has been extended to support streaming. 3. Laced Ring (LR), which uses about 1 rpt and offers an excellent compromise between storage compactness and performance of mesh traversal operators. 4. Zipper, an extension of LR, which uses about 6 bits per triangle (equivalently 0.19 rpt), therefore is the most compact representation. The triangle mesh data structures proposed in this thesis support the standard set of mesh connectivity operators introduced by the previously proposed Corner Table at an amortized constant time complexity. They can be constructed in linear time and space from the Corner Table or any equivalent representation. If geometry is stored as 16-bit coordinates, using Zipper instead of the Corner Table increases the size of the mesh that can be stored in core memory by a factor of about 8.

This thesis work will examin and present how to implement a Particle-In-Cell and a Fluid-Implicit-Particle (PIC / FLIP) fluid solver that takes advantage of the inherent parallelism of Digital Domain's sparse block optimized data structure, DB-Grid. The methods offer a hybrid approach between particle and grid based simulation. This thesis will also discuss and go through different approaches for storing and accessing the data associated with each particle. For dynamically create and remove attributes from the particles, Disney's open source API, Partio is used. Which is also used for saving the particles to disk. Finally how to expose C++ classes into Python by wrapping everything into a Python module using the Boost.Python API and discuss the benets of having a script language.

As software systems are growing in complexity and size, reliability becomes a major concern. A large degree of industrial and academic efforts for increasing software reliability are directed towards design, testing and validation—activities performed before the software is deployed. While such activities are fundamental for achieving high levels of confidence in software systems, bugs still occur after deployment resulting in costly software failures. This dissertation presents assertion-based repair, a novel approach for error recovery from insidious bugs that occur after the system is deployed. It describes the design and implementation of a repair framework for Java programs and evaluates the efficiency and effectiveness of the approach on repairing data structure errors in both software libraries and open-source stand-alone applications. Our approach introduces a new form of assertions, assertAndRepair, for developers to use when checking the consistency of the data structures manipulated by their programs with respect to a set of desired structural and data properties. The developer provides the properties in a Java boolean method, repOk, which returns a truth value based on whether a given data structure satisfies these properties. Upon an assertion violation due to a faulty structure, instead of terminating the execution, the structure is repaired, i.e., its fields are mutated such that the resulting structure satisfies the desired properties, and the program proceeds with its execution. To aid developers in detecting the causes of the fault, repair-logs are generated which provide useful information about the performed mutations. The repair process is performed using a novel algorithm that uses a systematic search based on symbolic execution to determine valuations for the structures’ fields that result in a valid structure. Our experiments on repairing both library data structures, as well as, stand-alone applications demonstrate the utility and efficiency of the approach in repairing large structures, enabling programs to recover from crippling errors and proceed with their executions. Assertion-based repair presents a novel post-deployment mechanism that integrates with existing and newly developed software, providing them with the defensive ability to recover from unexpected runtime errors. Programmers already understand the advantages of using assertions and are comfortable with writing them. Providing new analyses and powerful extensions for them presents an attractive direction towards building more reliable software. / text

The last few years have seen a resurgence of interest in the use of symbolic execution--program analysis technique developed more than three decades ago to analyze program execution paths. However, symbolic execution remains an expensive technique and scaling it remains a key technical challenge. There are two key factors that contribute to its cost: (1) the number of paths that need to be explored and (2) the cost of constraint solving, which is typically required for each path explored. Our insight is that the cost of symbolic execution can be reduced by an incremental approach, which uses static analysis and dynamic analysis to focus on relevant parts of code and reuse previous analysis results, thereby addressing both the key cost factors of symbolic execution. This dissertation presents Memoized Incremental Symbolic Execution, a novel approach that embodies our insight. Using symbolic execution in practice often requires several successive runs of the technique on largely similar underlying problems where successive problems differ due to some change, which may be to code, e.g., to fix a bug, to analysis parameters, e.g., to increase the path exploration depth, or to correctness properties, e.g., to check against stronger specifications that are written as assertions in code. Memoized Incremental Symbolic Execution, a three-fold approach, leverages the similarities in the successive problems to reduce the total cost of applying the technique. Our prototype tool-set is based on the Symbolic PathFinder. Experimental results show that Memoized Incremental Symbolic Execution enhances the efficacy of symbolic execution. / text

Software systems are now pervasive throughout our world. The reliability of these systems is an urgent necessity. A large degree of research effort on increasing software reliability is dedicated to requirements, architecture, design, implementation and testing---activities that are performed before system deployment. While such approaches have become substantially more advanced, software remains buggy and failures remain expensive. We take a radically different approach to reliability from previous approaches, namely contract-driven data structure repair for runtime error recovery, where erroneous executions of deployed software are corrected on-the-fly using rich behavioral contracts. Our key insight is to transform the software contract---which gives a high level description of the expected behavior---to an efficient implementation which repairs the erroneous data structures in the program state upon an error. To improve efficiency, scalability, and effectiveness of repair, in addition to rich behavioral contracts, we leverage the current erroneous state, dynamic behavior of the program, as well as repair history and abstraction. A core technical problem our approach to repair addresses is construction of structurally complex data that satisfy desired properties. We present a novel structure generation technique based on dynamic programming---a classic optimization approach---to utilize the recursive nature of the structures. We use our technique for constraint-based testing. It provides better scalability than previous work. We applied it to test widely-used web browsers and found some known and unknown bugs. Our use of dynamic programming in structure generation opens a new future direction to tackle the scalability problem of data structure repair. This research advances our ability to develop correct programs. For programs that already have contracts, error recovery using our approach can come at a low cost. The same contracts can be used for systematically testing code before deployment using existing as well as our new techniques. Thus, we enable a novel unification of software verification and error recovery. / text

Dissertation (Ph.D.)--Auburn University, 2007. / Abstract. Includes bibliographic references (p.127-136).