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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

Taintx: A System for Protecting Sensitive Documents

Dillon, Patrice 06 August 2009 (has links)
Across the country members of the workforce are being laid off due to downsizing. Most of those people work for large corporations and have access to important company documents. There have been several studies suggesting that employees are taking critical information after learning they will be laid off. This becomes an issue and a threat to a corporation's security. Corporations are then placed in a position to make sure sensitive documents never leave the company. In this study we build a system that is used to assist corporations and systems administrators. This system will prevent users from taking sensitive documents. The system used in this study helps to maintain a level of security that is not only beneficial but is a crucial part of managing a corporation, and enhancing its ability to compete in an aggressive market.
262

Um sistema de arquivos com blocos distribuídos e acesso a informações de localidade de dados. / A file system with distributed blocks and access to data locality information.

Sugawara Júnior, Ricardo Ryoiti 30 April 2014 (has links)
Muitos sistemas recentes de processamento paralelo e distribuído trabalham com acesso intensivo a dados, combinando facilidades de computação e armazenamento de dados para a construção de sistemas de grande escala, com custos reduzidos. Nesses sistemas, a interligação de um grande número de nós resulta na divisão sucessiva da capacidade de transferência, tornando a movimentação de dados um importante fator de limitação de desempenho. Ao se escalonar as tarefas computacionais em nós próximos dos dados, melhorias significativas no desempenho podem ser obtidas. Entretanto, a informação sobre a localidade dos dados não está facilmente acessível para o programador. Seu uso requer a interação com rotinas internas dos sistemas de arquivos, ou exige a adoção de um modelo de programação específico, normalmente associado a uma plataforma de execução já preparada para escalonar tarefas com aproveitamento da localidade dos dados. Este trabalho desenvolve a proposta de um mecanismo e interface para prover acesso a informações de localidade, além de permitir o controle da distribuição de novos dados. As operações de consulta e controle são realizadas por meio de arquivos e diretórios especiais, adicionados de forma transparente a um sistema de arquivos com blocos de dados distribuídos, apropriado para a execução em ambientes de processamento paralelo. O sistema é denominado parfs e permite obter as informações de localidade com operações de leitura e escrita em arquivos comuns, sem a necessidade do uso de bibliotecas ou modelos de programação específicos. Testes foram realizados para avaliar a proposta. Utilizando o escalonamento seletivo de operações de acesso a dados, baseado na informação de localidade, foram obtidos ganhos significativos de desempenho nessas operações. / Many recent data intensive parallel processing systems are built with cost effective hardware and combine compute and storage facilities. In such systems, interconnecting large numbers of nodes results in bandwidth-bisecting networks, making data movement an important performance limiting factor. By distributing jobs near data, significant performance improvements can be achieved. However, data locality information is not easily available to the programmer. It requires interaction with file system internals, or the adoption of custom programming and run-time frameworks providing embedded locality-aware job scheduling. This document develops a proposal of a mechanism and an interface to provide locality information and new data placement control. The query and control tasks are performed through special file and directories transparently added to a distributed file system, suitable for parallel processing environments. The file system is called parfs and allows the use of locality by read and write operations over regular files, with no need of libraries or specific programming models. Tests were conducted to assess the feasibility of the proposal. Through selective scheduling of data operations, based on locality information, significant performance gains were obtained in such operations.
263

The small-large divide: The development of infant abilities to discriminate small from large sets

Posid, Tasha Irene January 2015 (has links)
Thesis advisor: Sara Cordes / Thesis advisor: Ellen Winner / Evidence suggests that humans and non-human animals have access to two distinct numerical representation systems: a precise "object-file" system used to visually track small quantities (<4) and an approximate, ratio-dependent analog magnitude system used to represent all natural numbers. Although many studies to date indicate that infants can discriminate exclusively small sets (e.g., 1 vs. 2, 2 vs. 3) or exclusively large sets (4 vs. 8, 8 vs. 16), a robust phenomenon exists whereby they fail to compare sets crossing this small-large boundary (2 vs. 4, 3 vs. 6) despite a seemingly favorable ratio of difference between the two set sizes. Despite these robust failures in infancy (up to 14 months), studies suggest that 3-year old children no longer encounter difficulties comparing small from large sets, yet little work has explored the development of this phenomenon between 14 months and 3 years of age. The present study investigates (1) when in development infants naturally overcome this inability to compare small vs. large sets, as well as (2) what factors may facilitate this ability: namely, perceptual variability and/or numerical language. Results from three cross-sectional studies indicate that infants begin to discriminate between small and large sets as early as 17 months of age. Furthermore, infants seemed to benefit from perceptual variability of the items in the set when making these discriminations. Moreover, although preliminary evidence suggests that a child's ability to verbally count may correlate with success on these discriminations, simply exposure to numerical language (in the form of adult modeling of labeling the cardinality and counting the set) does not affect performance. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.
264

"Influência da velocidade de rotação e do número de usos no tempo de trabalho e na fratura de instrumentos rotatórios de níquel-titânio" / Influence of rotational speed and simulated clinical use on breakage and instrumentation time of rotary nickel-titanium files

Lauretti, Luis Guilherme Bertoni 05 April 2006 (has links)
Inúmeras são as vantagens da utilização de instrumentos rotatórios de níquel-titânio no preparo químico-cirúrgico, como por exemplo, melhor modelagem dos canais curvos e uma diminuição significativa no tempo de trabalho. Todavia, a maior preocupação no uso desses instrumentos tem sido a sua fratura, principalmente, por sua ocorrência estar ligada a diferentes fatores. O objetivo do presente estudo foi avaliar a influência da velocidade de rotação e do número de usos, no tempo de trabalho e na ocorrência de fraturas de instrumentos de dois sistemas rotatórios de níquel-titânio (K3 e RaCe), em canais simulados com mesmo ângulo de curvatura. Foram avaliados os instrumentos 25/.04 dos dois sistemas nas velocidades de 180, 350, 600 rpm ao instrumentarem 5 mm referentes à curvatura dos canais simulados. Para cada velocidade foram utilizadas limas com 1, 2 e 3 usos. Um contra-ângulo foi adaptado a um dispositivo calibrado para realizar movimentos padronizados de penetração nos canais simulados. Foram mensurados: o tempo necessário para instrumentar a curvatura do canal e a quantidade de fraturas ocorridas. Os resultados obtidos foram submetidos a ANOVA sendo em seguida empregado o teste de Tukey (&#945;=5%). Sob as condições desse experimento, o aumento da velocidade diminuiu o tempo de instrumentação em ambos os sistemas. Os instrumentos RaCe prepararam o canal em menor tempo do que os instrumentos K3 nas velocidades de 350 e 600 rpm (p<0,05), não havendo diferença em 180 rpm (p>0,05). Ocorreu maior número de instrumentos fraturados nas velocidades de 180 e 600 rpm para o sistema RaCe e de 600 rpm para o K3, e nenhuma fratura na velocidade de 350 rpm para ambos. O número de usos não influenciou o tempo de trabalho para nenhum sistema (p>0,05), porém, o número de fraturas aumentou proporcionalmente ao aumento do número de usos, exceto na velocidade de 350 rpm na qual não ocorreram fraturas. Os instrumentos RaCe apresentaram maior índice de fratura para a velocidade de 180 rpm (30%) do que para 600 rpm (13,33%). A velocidade de 350 rpm foi a mais segura para os instrumentos de ambos os sistemas. / Use of nickel-titanium rotary instruments has many advantages like better shaping of curved canals and lower working time. However, instrument fracture has always been a serious concern in root canal treatment because it involves a lot of factors. The aim of this study was to evaluate the influence of rotational speed and number of uses on the preparation time and incidence of fractures of K3 and RaCe instruments, using simulated root canals with the same angle of curvature. Nickel-titanium 25/.04- tapered instruments of both rotary systems were tested at 180, 350 and 600 rpm during shaping of 5 mm curvature’s extent. The files were used 3 times in each rotational speed. A contra-angle electric handpiece was mounted on a machine that was calibrated to deliver a constant penetration movement. Working time and incidence of fractures were measured. The results were analyzed statistically using a one-way analysis of variance with a post-hoc Tukey test (&#945;=5%). Under the conditions of this study, higher rotational speeds reduced preparation time for both rotary systems. RaCe instruments showed lower preparation time than K3 instruments at 350 and 600 rpm (p<0,05). There was no significant difference at 180 rpm (p>0,05). There was a higher incidence of fractures at 180 and 600 rpm for RaCe instruments and at 600 rpm for K3 instruments. No file breakage occurred at 350 rpm for both instruments. Preparation time was not influenced significantly by the frequency that the files were used (p>0,05). Incidence of fractures increased with an increase in the number of file usage, unless at 350 rpm in which none of the files fractured. At 180 rpm, RaCe instruments showed a higher incidence of breakage than at 600 rpm. Rotational speed of 350 rpm was the safest for both kind of instruments tested in this study.
265

Implementação de um sistema de arquivos para uma plataforma de computação reconfigurável / A file system implementation for a reconfigurable computing platform

Sanches, Adriano Kaminski 20 September 2006 (has links)
Em um sistema computacional, os dados são armazenados na unidade de armazenamento, segundo alguma lógica, em estruturas denominadas arquivos. O Sistema de Arquivos é o responsável por estruturar, identificar, acessar, proteger e gerenciar esses arquivos, além de agir como um elo de ligação entre o usuário e o dispositivo, traduzindo comandos de alta abstração (oriundos do usuário) em comandos de baixo nível, compreensível a unidade de armazenamento. O presente trabalho visa a implementação de um sistema de arquivos para aplicação em dispositivos móveis baseado em computação reconfigurável. Tal sistema servirá de suporte para as aplicações que necessitem armazenar e/ou restaurar grande volume de dados, como a aquisição de imagens digitalizadas de câmeras CMOS. Este sistema também será utilizado como uma ferramenta inicial para o desenvolvimento de um módulo de armazenamento em uma placa baseada em computação reconfigurável a ser utilizada para fins didáticos. O sistema de arquivos implementado foi a FAT16 e o dispositivo de armazenamento de massa utilizado foram os cartões de memória SD-Secure Digital e MMC-MultiMediaCard / In computational systems, usually the data are stored in storage units, according to some logic, in structures called files. The File System is responsible for structure, identification, access, protection and management of the files. It also acts as a connector link between the user and the device, translating high level commands (derived for the user) into commands of low level, understandable for the storage unit. The present work aims to implement a File System for application in mobile devices based on reconfigurable computation. Such system will act as a support for the applications that need to store and/or to restore large volume of data, such as the acquisition of digital images from CMOS cameras. This system will also be used as an initial tool for the development of a storage module of a board, based on reconfigurable computation, to be used for didactic purposes. The implemented File System is based on FAT16 and the storage device used was the memory cards SD (Secure Digital) and MMC (MultiMedia- Card)
266

Arquitetura e implementação de um sistema distribuído e recuperação de informação / Architecture and implementation of a distributed information retrieval system

Augusto, Luiz Daniel Creao 09 June 2010 (has links)
A busca por documentos relevantes ao usuário é um problema que se torna mais custoso conforme as bases de conhecimento crescem em seu ritmo acelerado. Este problema passou a resolvido por sistemas distribuídos, devido a sua escalabilidade e tolerância a falhas. O desenvolvimento de sistemas voltados a estas enormes bases de conhecimento -- e a maior de todas, a Internet -- é uma indústria que movimenta bilhões de dólares por ano no mundo inteiro e criou gigantes. Neste trabalho, são apresentadas e discutidas estruturas de dados e arquiteturas distribuídas que tratem o problema de indexar e buscar grandes coleções de documentos em sistemas distribuídos, alcançando grande desempenho e escalabilidade. Serão também discutidos alguns dos grandes sistemas de busca da atualidade, como o Google e o Apache Solr, além do planejamento de uma grande aplicação com protótipo em desenvolvimento. Um projeto próprio de sistema de busca distribuído foi implementado, baseado no Lucene, com idéias coletadas noutros trabalhos e outras novas. Em nossos experimentos, o sistema distribuído desenvolvido neste trabalho superou o Apache Solr com um vazão 37,4\\% superior e mostrou números muito superiores a soluções não-distribuídas em hardware de custo muito superior ao nosso cluster. / The search for relevant documents for the final user is a problem that becomes more expensive as the databases grown faster. The solution was brought by distributed systems, because of its scalability and fail tolerance. The development of systems focused on enormous databases -- including the World Wide Web -- is an industry that involves billions of dollars in the world and had created giants. In this work, will be presented and discussed data structures and distributed architectures related to the indexes and searching in great document collections in distributed systems, reaching high performance and scalability. We will also discuss some of the biggest search engines, such as Google e Apache Solr, and the planning of an application with a developing prototype. At last, a new project of a distributed searching system will be presented and implemented, based on Lucene, with ideas from other works and new ideas of our own. On our tests, the system developed in this work had throughput 37.4\\% higher than Apache Solr and revealed higher performance than non-distributed solutions in a hardware more expensive than our cluster.
267

Some results on FPGAs, file transfers, and factorizations of graphs.

January 1998 (has links)
by Pan Jiao Feng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 89-93). / Abstract also in Chinese. / Abstract --- p.i / Acknowledgments --- p.v / List of Tables --- p.x / List of Figures --- p.xi / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Graph definitions --- p.2 / Chapter 1.2 --- The S box graph --- p.2 / Chapter 1.3 --- The file transfer graph --- p.4 / Chapter 1.4 --- "(g, f)-factor and (g, f)-factorization" --- p.5 / Chapter 1.5 --- Thesis contributions --- p.6 / Chapter 1.6 --- Organization of the thesis --- p.7 / Chapter Chapter 2. --- On the Optimal Four-way Switch Box Routing Structures of FPGA Greedy Routing Architectures --- p.8 / Chapter 2.1 --- Introduction --- p.9 / Chapter 2.1.1 --- FPGA model and S box model --- p.9 / Chapter 2.1.2 --- FPGA routing --- p.10 / Chapter 2.1.3 --- Problem formulation --- p.10 / Chapter 2.2 --- Definitions and terminology --- p.12 / Chapter 2.2.1 --- General terminology --- p.12 / Chapter 2.2.2 --- Graph definitions --- p.15 / Chapter 2.2.3 --- The S box graph --- p.15 / Chapter 2.3 --- Properties of the S box graph and side-to-side graphs --- p.16 / Chapter 2.3.1 --- On the properties of the S box graph --- p.16 / Chapter 2.3.2 --- The properties of side-to-side graphs --- p.19 / Chapter 2.4 --- Conversion of the four-way FPGA routing problem --- p.23 / Chapter 2.4.1 --- Conversion of the S box model --- p.24 / Chapter 2.4.2 --- Conversion of the DAAA model --- p.26 / Chapter 2.4.3 --- Conversion of the DADA model --- p.27 / Chapter 2.4.4 --- Conversion of the DDDA model --- p.28 / Chapter 2.5 --- Low bounds of routing switches --- p.28 / Chapter 2.5.1 --- The lower bound of the DAAA model --- p.29 / Chapter 2.5.2 --- The lower bound of the DADA model --- p.30 / Chapter 2.5.3 --- The lower bound of the DDDA model --- p.31 / Chapter 2.6 --- Optimal structure of one-side predetermined four-way FPGA routing --- p.32 / Chapter 2.7 --- Optimal structures of two-side and three-side predetermined four-way FPGA routing --- p.45 / Chapter 2.7.1 --- Optimal structure of two-side predetermined four-way FPGA routing --- p.46 / Chapter 2.7.2 --- Optimal structure of three-side predetermined four-way FPGA routing --- p.47 / Chapter 2.8 --- Conclusion --- p.49 / Appendix --- p.50 / Chapter Chapter 3. --- "Application of (0, f)-Factorization on the Scheduling of File Transfers" --- p.53 / Chapter 3.1 --- Introduction --- p.53 / Chapter 3.1.1 --- "(0,f)-factorization" --- p.54 / Chapter 3.1.2 --- File transfer model and its graph --- p.54 / Chapter 3.1.3 --- Previous results --- p.56 / Chapter 3.1.4 --- Our results and outline of the chapter --- p.56 / Chapter 3.2 --- NP-completeness --- p.57 / Chapter 3.3 --- Some lemmas --- p.58 / Chapter 3.4 --- Bounds of file transfer graphs --- p.59 / Chapter 3.5 --- Comparison --- p.62 / Chapter 3.6 --- Conclusion --- p.68 / Chapter Chapter 4. --- "Decomposition Graphs into (g,f)-Factors" --- p.69 / Chapter 4.1 --- Introduction --- p.69 / Chapter 4.1.1 --- "(g,f)-factors and (g,f)-factorizations" --- p.69 / Chapter 4.1.2 --- Previous work --- p.70 / Chapter 4.1.3 --- Our results --- p.72 / Chapter 4.2 --- Proof of Theorem 2 --- p.73 / Chapter 4.3 --- Proof of Theorem 3 --- p.79 / Chapter 4.4 --- Proof of Theorem 4 --- p.80 / Chapter 4.5 --- Related previous results --- p.82 / Chapter 4.6 --- Conclusion --- p.84 / Chapter Chapter 5. --- Conclusion --- p.85 / Chapter 5.1 --- About graph-based approaches --- p.85 / Chapter 5.2 --- FPGA routing --- p.87 / Chapter 5.3 --- The scheduling of file transfer --- p.88 / Bibliography --- p.89 / Vita --- p.94
268

Augmenting cloud file systems with erasure coding: a practical perspective. / CUHK electronic theses & dissertations collection

January 2013 (has links)
Lin, Jian. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 44-49). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.
269

Design of a personal genealogical data base system

Bird, Mary Jo January 2010 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
270

Solo32, a Concurrent Pascal operating system with UNIX interfaces

Wilde, Martin January 2010 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries

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