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Estruturação de banco de dados a partir do mapeamento geotécnico, aplicado à região de Ribeirão Preto (SP) ; Structuration of database from geological engineering mapping applied to Ribeirão Preto area (SP)

Souza, Gracinete Bastos de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/08/2005 Português
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O objetivo do presente estudo foi demonstrar que as informações produzidas pelos trabalhos científicos, quando organizadas e colocadas em formato eletrônico (digital), facilitam a utilização por pessoas a quem venham interessar. Foi desenvolvido um projeto em mapeamento geotécnico, utilizando-se um sistema de informação geográfica e um projeto dentro do ambiente de uma linguagem de programação(elaboração de um aplicativo). Observou-se que esses instrumentos proporcionam facilidade e rapidez na manipulação, na busca, no armazenamento, na visualização, na consulta e na análise da informação. A Pesquisa teve lugar na região de Ribeirão Preto (SP) e, utilizando-se o desenvolvimento do projeto de mapeamento geotécnico na escala 1:50.000 (escala regional), foi feita a análise das formas de organização das informações no formato eletrônico considerando o sistema de informação geográfica e usando um aplicativo externo ao SIG. Puderam- e verificar vantagens e desvantagens do uso desses instrumentos, em relação ao formato não-eletrônico (e forma de papel). Além do SIG (SPRING4.0, desenvolvido pelo Instituto Nacional de Pesquisas Espaciais – INPE) e o aplicativo desenvolvido na linguagem de programação Visual Basic (comercializada pela Microsoft)...

Graph spectra and modal dynamics of oscillatory networks

Ayazifar, Babak, 1967-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 191 leaves; 1004633 bytes; 1004415 bytes; application/pdf; application/pdf
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Our research focuses on developing design-oriented analytical tools that enable us to better understand how a network comprising dynamic and static elements behaves when it is set in oscillatory motion, and how the interconnection topology relates to the spectral properties of the system. Such oscillatory networks are ubiquitous, extending from miniature electronic circuits to large-scale power networks. We tap into the rich mathematical literature on graph spectra, and develop theoretical extensions applicable to networks containing nodes that have finite nonnegative weights-including nodes of zero weight, which occur naturally in the context of power networks. We develop new spectral graph-theoretic results spawned by our engineering interests, including generalizations (to node-weighted graphs) of various structure-based eigenvalue bounds. The central results of this thesis concern the phenomenon of dynamic coherency, in which clusters of vertices move in unison relative to each other. Our research exposes the relation between coherency and network structure and parameters. We study both approximate and exact dynamic coherency. Our new understanding of coherency leads to a number of results. We expose a conceptual link between theoretical coherency and the confinement of an oscillatory mode to a node cluster. We show how the eigenvalues of a coherent graph relate to those of its constituent clusters.; (cont.) We use our eigenvalue expressions to devise a novel graph design algorithm; given a set of vertices (of finite positive weight) and a desired set of eigenvalues...

The Curl Graphics2d immediate mode rendering API; Curl Graphics 2d immediate mode rendering API

McGuire, Morgan, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 69 leaves; 4072575 bytes; 4079339 bytes; application/pdf; application/pdf
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(cont.) 170 thousand lines of code in the Curl language. Morgan McGuire has worked on computer graphics and imaging at Morgan Systems, the NEC Research Institute and the IBM T. J. Watson Research Center. He is currently employed by Curl Corporation as senior architect of the computer graphics group.; The Curl Graphics2d API (Graphics2d) is a 2d immediate mode rendering API for the Curl Internet content language. The unique capabilities of the Curl language enable the API to take the form of a graphics language rather than a simple library of routines. This graphics language offers a basis set of primitives and an extension mechanism that allows 2d and 3d graphics without sacrificing performance. Graphics2d attempts to achieve minimalist simplicity by identifying fundamental concepts in 2d rendering and representing each of those concepts with a single interface class or method. These interfaces may be implemented by user (parties outside of Curl, possibly executing untrusted code) code to interact with other modules built to the API. However, user code will typically use the implementation provided with Curl to build graphics intense applications rather than extending the API directly. As with any large API, the philosophy and crucial design points comprise the essence of Graphics2d...

Signal processing in biological cells : proteins, networks, and models

Said, Maya Rida, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 210 p.; 11825455 bytes; 11825355 bytes; application/pdf; application/pdf
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This thesis introduces systematic engineering principles to model, at different levels of abstraction the information processing in biological cells in order to understand the algorithms implemented by the signaling pathways that perform the processing. An example of how to emulate one of these algorithms in other signal processing contexts is also presented. At a high modeling level, the focus is on the network topology rather than the dynamical properties of the components of the signaling network. In this regime, we examine and analyze the distribution and properties of the network graph. Specifically, we present a global network investigation of the genotype/phenotype data-set recently developed for the yeast Saccharomyces cerevisiae from exposure to DNA damaging agents, enabling explicit study of how protein-protein interaction network characteristics may be associated with phenotypic functional effects. The properties of several functional yeast networks are also compared and a simple method to combine gene expression data with network information is proposed to better predict pathophysiological behavior. At a low level of modeling, the thesis introduces a new framework for modeling cellular signal processing based on interacting Markov chains. This framework provides a unified way to simultaneously capture the stochasticity of signaling networks in individual cells while computing a deterministic solution which provides average behavior. The use of this framework is demonstrated on two classical signaling networks: the mitogen activated protein kinase cascade and the bacterial chemotaxis pathway. The prospects of using cell biology as a metaphor for signal processing are also considered in a preliminary way by presenting a surface mapping algorithm based on bacterial chemotaxis.; by Maya Rida Said.; Thesis (Sc. D.)--Massachusetts Institute of Technology...

MintEra : a testing environment for Java programs; Mint Era : a testing environment for Java programs

Al-Naffouri, Basel Y
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 100 p.; 4492942 bytes; 4498330 bytes; application/pdf; application/pdf
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We introduce MintEra, an automatic testcase generator and verifier. Using an simple, easy-to-read yet expressive language called AAL, users can specify representation- invariants and assertions within programs. MintEra uses the representation-invariant to generate testcases and translates assertions into Java run-time checks, which verify testcases. The tool then graphically visualize failed testcases to help users debug their code. MintEra encourages documentation of programs by using specification to test and verify code. Effectively, the tool checks code and specification against each other. Thus, MintEra helps users ensure correctness of their programs as well as their specification. In this thesis, we provide a number of extra features that we hope would develop MintEra into an effective tool that could be used by the general software engineering community.; by Basel Y. Al-Naffouri.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.; Includes bibliographical references (p. 99-100).

Scalable fault management architecture for dynamic optical networks : an information-theoretic approach

Wen, Yonggang
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 262 leaves
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All-optical switching, in place of electronic switching, of high data-rate lightpaths at intermediate nodes is one of the key enabling technologies for economically scalable future data networks. This replacement of electronic switching with optical switching at intermediate nodes, however, presents new challenges for fault detection and localization in reconfigurable all-optical networks. Presently, fault detection and localization techniques, as implemented in SONET/G.709 networks, rely on electronic processing of parity checks at intermediate nodes. If similar techniques are adapted to all-optical reconfigurable networks, optical signals need to be tapped out at intermediate nodes for parity checks. This additional electronic processing would break the all-optical transparency paradigm and thus significantly diminish the cost advantages of all-optical networks. In this thesis, we propose new fault-diagnosis approaches specifically tailored to all-optical networks, with an objective of keeping the diagnostic capital expenditure and the diagnostic operation effort low. Instead of the aforementioned passive monitoring paradigm based on parity checks, we propose a proactive lightpath probing paradigm: optical probing signals are sent along a set of lightpaths in the network...

Convex optimization methods for model reduction

Sou, Kin Cheong, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 161 p.
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Model reduction and convex optimization are prevalent in science and engineering applications. In this thesis, convex optimization solution techniques to three different model reduction problems are studied.Parameterized reduced order modeling is important for rapid design and optimization of systems containing parameter dependent reducible sub-circuits such as interconnects and RF inductors. The first part of the thesis presents a quasi-convex optimization approach to solve the parameterized model order reduction problem for linear time-invariant systems. Formulation of the model reduction problem as a quasi-convex program allows the flexibility to enforce constraints such as stability and passivity in both non-parameterized and parameterized cases. Numerical results including the parameterized reduced modeling of a large RF inductor are given to demonstrate the practical value of the proposed algorithm.A majority of nonlinear model reduction techniques can be regarded as a two step procedure as follows. First the state dimension is reduced through a projection, and then the vector field of the reduced state is approximated for improved computation efficiency. Neither of the above steps has been thoroughly studied. The second part of this thesis presents a solution to a particular problem in the second step above...

A multi-tier framework for dynamic data collection, analysis, and visualization

Ke, Xian, 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 56 leaves; 3176956 bytes; 3181740 bytes; application/pdf; application/pdf
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This thesis describes a framework for collecting, analyzing, and visualizing dynamic data, particularly data gathered through Web questionnaires. The framework addresses challenges such as promoting user participation, handling missing or invalid data, and streamlining the data interpretation process. Tools in the framework provide an intuitive way to build robust questionnaires on the Web and perform on-the-fly analysis and visualization of results. A novel 2.5-dimensional dynamic response-distribution visualization allows subjects to compare their results against others immediately after they have submitted their response, thereby encouraging active participation in ongoing research studies. Other modules offer the capability to quickly gain insight and discover patterns in user data. The framework has been implemented in a multi-tier architecture within an open-source, Java-based platform. It is incorporated into Risk Psychology Network, a research and educational project at MIT's Laboratory for Financial Engineering.; by Xian Ke.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.; Includes bibliographical references (leaves 52-53).

Fighting phishing at the user interface

Wu, Min, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 199 p.
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The problem that this thesis concentrates on is phishing attacks. Phishing attacks use email messages and web sites designed to look as if they come from a known and legitimate organization, in order to deceive users into submitting their personal, financial, or computer account information online at those fake web sites. Phishing is a semantic attack. The fundamental problem of phishing is that when a user submits sensitive information online under an attack, his mental model about this submission is different from the system model that actually performs this submission. Specifically, the system sends the data to a different web site from the one where the user intends to submit the data. The fundamental solution to phishing is to bridge the semantic gap between the user's mental model and the system model. The user interface is where human users interact with the computer system. It is where a user's intention transforms into a system operation. It is where the semantic gap happens under phishing attacks. And therefore, it is where the phishing should be solved. There are two major approaches to bridge the semantic gap at the user interface. One approach is to reflect the system model to the user.; (cont.) Anti-phishing toolbars and the browser's security indicators take this approach. User studies in this thesis show that this approach is not effective at preventing phishing. Users are required to constantly pay attention to the toolbar and are expected to have the expertise to always correctly interpret the toolbar message. Normal users meet neither of these requirements. The other approach is to let users tell the system their intentions when they are submitting data online. The system can then check if the actual submission meets the user's intention or not. If there is a semantic gap...

Simulation of timed input/output automata; Simulation of TIOA

Mavrommatis, Panayiotis P
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 74 p.
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This Master of Engineering Thesis describes the design, implementation, and usage of the TIOA Simulator. The TIOA Simulator, along with the other components of the TIOA Toolset aims to provide a framework for developing dependable distributed systems. The project is based on the Timed Input/Output Automaton framework, and supports TIOA, a formal language for specifying timed I/O automata. Simulation of TIOA programs is useful in the process of testing the proposed system over a specific set of executions. During the execution the Simulator is able to test proposed invariants and validate a proposed simulation relation between the system's implementation and its specification. A step correspondence between the steps of the implementation and the specification drives the validation of the simulation relation. The identification and validation of the invariants and the simulation relation constitutes the first step towards a formal verification of the system's correctness. The proposed step correspondence can be used in a formal proof to show that the proposed relation is indeed a simulation relation.; by Panayiotis P. Mavrommatis.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science...

Proactive techniques for correct and predictable Internet routing

Feamster, Nicholas G. (Nicholas Greer), 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 193 p.; 2205480 bytes; 2242457 bytes; application/pdf; application/pdf
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The Internet is composed of thousands of autonomous, competing networks that exchange reachability information using an interdomain routing protocol. Network operators must continually reconfigure the routing protocols to realize various economic and performance goals. Unfortunately, there is no systematic way to predict how the configuration will affect the behavior of the routing protocol or to determine whether the routing protocol will operate correctly at all. This dissertation develops techniques to reason about the dynamic behavior of Internet routing, based on static analysis of the router configurations, before the protocol ever runs on a live network. Interdomain routing offers each independent network tremendous flexibility in configuring the routing protocols to accomplish various economic and performance tasks. Routing configurations are complex, and writing them is similar to writing a distributed program; the (unavoidable) consequence of configuration complexity is the potential for incorrect and unpredictable behavior. These mistakes and unintended interactions lead to routing faults, which disrupt end-to-end connectivity. Network operators writing configurations make mistakes; they may also specify policies that interact in unexpected ways with policies in other networks.; (cont.) To avoid disrupting network connectivity and degrading performance...

Attacks on the Fiat-Shamir paradigm and program obfuscation

Tauman Kalai, Yael
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 119 p.; 1172348 bytes; 1180019 bytes; application/pdf; application/pdf
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The goal of cryptography is to construct *secure* and *efficient* protocols for various tasks. Unfortunately, it is often the case that protocols that are provably secure are not efficient enough for practical use. As a result, most protocols used in practice are *heuristics* that lack proofs of security. These heuristics are typically very efficient and are believed to be secure, though no proof of security has been provided. In this thesis we study the security of some of these popular heuristics. In particular, we focus on two types of heuristics: (1) the Fiat-Shamir heuristic for constructing digital signature schemes, and (2) heuristics for obfuscation. We show that, in some sense, both of these types of heuristics are insecure. Thus, this thesis consists of two parts: (1) The insecuirty of the Fiat-Shamir paradigm: The Fiat-Shamir heuristic provides a general method for transforming secure 3-round public-coin identification schemes into digital signature schemes. The idea of the transformation is to replace the random (second-round) message of the verifier in the identification scheme, with the value of some deterministic hash function evaluated on the first-round message (sent by the prover) and on the message to be signed.; (cont.) The Fiat-Shamir methodology for producing digital signature schemes quickly gained popularity both in theory and in practice...

A theory and toolkit for the mathematics of privacy : methods for anonymizing data while minimizing information loss

Katirai, Hooman
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 86 leaves; 14904672 bytes; 14904307 bytes; application/pdf; application/pdf
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Privacy laws are an important facet of our society. But they can also serve as formidable barriers to medical research. The same laws that prevent casual disclosure of medical data have also made it difficult for researchers to access the information they need to conduct research into the causes of disease. But it is possible to overcome some of these legal barriers through technology. The US law known as HIPAA, for example, allows medical records to be released to researchers without patient consent if the records are provably anonymized prior to their disclosure. It is not enough for records to be seemingly anonymous. For example, one researcher estimates that 87.1% of the US population can be uniquely identified by the combination of their zip, gender, and date of birth - fields that most people would consider anonymous. One promising technique for provably anonymizing records is called k-anonymity. It modifies each record so that it matches k other individuals in a population - where k is an arbitrary parameter. This is achieved by, for example, changing specific information such as a date of birth, to a less specific counterpart such as a year of birth.; (cont.) Previous studies have shown that achieving k-anonymity while minimizing information loss is an NP-hard problem; thus a brute force search is out of the question for most real world data sets. In this thesis...

Actor-critic algorithms

Konda, Vijaymohan (Vijaymohan Gao), 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 147 leaves; 11090533 bytes; 11090292 bytes; application/pdf; application/pdf
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Many complex decision making problems like scheduling in manufacturing systems, portfolio management in finance, admission control in communication networks etc., with clear and precise objectives, can be formulated as stochastic dynamic programming problems in which the objective of decision making is to maximize a single "overall" reward. In these formulations, finding an optimal decision policy involves computing a certain "value function" which assigns to each state the optimal reward one would obtain if the system was started from that state. This function then naturally prescribes the optimal policy, which is to take decisions that drive the system to states with maximum value. For many practical problems, the computation of the exact value function is intractable, analytically and numerically, due to the enormous size of the state space. Therefore one has to resort to one of the following approximation methods to find a good sub-optimal policy: (1) Approximate the value function. (2) Restrict the search for a good policy to a smaller family of policies. In this thesis, we propose and study actor-critic algorithms which combine the above two approaches with simulation to find the best policy among a parameterized class of policies. Actor-critic algorithms have two learning units: an actor and a critic. An actor is a decision maker with a tunable parameter. A critic is a function approximator. The critic tries to approximate the value function of the policy used by the actor...

Factor graphs and MCMC approaches to iterative equalization of nonlinear dispersive channels; Factor graphs and Markov chain Monte Carlo approaches to iterative equalization of nonlinear dispersive channels

Kashif, Faisal M. (Faisal Mahmood)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 90 p.
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In this work, equalization for nonlinear dispersive channels is considered. Nonlinear communication channels can lead to significant degradations when nonlinearities are not taken into account at either the receiver or the transmitter. In many cases, the nonlinearity of the channel precludes the use of spectrally efficient signaling schemes to achieve high data-rates and the bandwidth efficiency. Satellite channel is a typical case of nonlinear channel that needs to be used efficiently. We develop two novel equalization strategies for a general class of nonlinear channels. Both strategies are based on iterating between decoding and equalization, termed as iterative equalization. The first strategy is a factor graph based equalizer that converts the nonlinear channel equalization problem into forward-backward algorithm on hidden Markov model (HMM). The equalizer is implemented via the sum-product algorithm on the factor graph representation of the channel and receiver blocks. The second equalization strategy is based on Markov chain Monte Carlo (MCMC) methods. We typecast the problem of executing forward-backward algorithm on HMM into an MCMC domain problem and develop four different types of MCMC equalizers.; (cont.) These solutions have different performance and magnitudes of complexity. For the purpose of performance analysis of our equalizers...

High performance amplifier topologies implemented with a micro-machined vibrating capacitor

Aina, Akin Adeniyi, 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 206 leaves; 11979149 bytes; 12005741 bytes; application/pdf; application/pdf
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In this work, the design of a MEMS based differential amplifier is investigated. The goal of this investigation is to design, fabricate and characterize a differential amplifier whose performance is based on a physically coupled, but electrically isolated fully differential mechanical transconductor input stage that is fabricated using SOI-MEMS technology. The MEMS sensor will act as a vibrating capacitor input stage. It will provide galvanic isolation and up-modulation of the input signal as it vibrates. The galvanic isolation facilitates low-leakage inputs and a very wide input common mode voltage range. The up-modulation provides a means for achieving a low input referred offset voltage and low-noise via the use of correlated double sampling or chopper stabilization. At the system level, this amplifier consists of two major loops: the drive loop and a sense loop. The drive loop includes half of the MEMS structure along with some electronics and provides a means of moving the beam at a constant frequency. The drive loop's design was facilitated by describing function analysis. The drive loop vibrated the beam at its mechanical resonance because at that frequency, the displacement of the beam is maximized for a given electrostatic force and consequently...

Imaging of absolute electrical properties using electroquasistatic and magnetoquasistatic sensor arrays

Schlicker, Darrell Eugene
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 390 p.
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This research focuses on the enhancement of electroquasistatic and magnetoquasistatic nondestructive evaluation techniques. The terminals of the sensors involved are connected to conductors which are traditionally located on a single plane and have a spatially-periodic structure. The sensor operates as a two-port device with one conductor used to excite the sensor and a second conductor used to sense the response to test materials. Existing measurement capabilities are extended: 1. Multiple sensing elements are incorporated into electroquasistatic and magneto-quasistatic sensors such that the response can be accurately modeled. Single sensing element sensors which remain stationary on a test material's surface cannot provide information about variations in material properties along the surface. Scanning of a single element sensor requires many passes in order to provide high resolution property mapping of the surface. By introducing an array of sensing elements it is possible to provide stationary resolution and increase the rate at which a test material's surface can be mapped. Multiple sensing elements can also provide the ability to independently measure material properties that may otherwise be inseparable.; (cont.) The sensors developed allow semi-analytic models to accurately predict their response to layered-media. The sensor is then able to measure absolute material properties using only an air calibration. 2. Existing sensor modeling methods are extended to address new sensor structures. Traditional formulations for models of spatially-periodic sensors were limited to simple conductor patterns on a single plane. These models have been reformulated to address more complex conductor patterns and allow placement on multiple sensor planes. In addition...

Designing end user information environments built on semistructured data models

Quan, Dennis A. (Dennis Arthur), 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 214 p.; 12331358 bytes; 12331164 bytes; application/pdf; application/pdf
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Today's information systems were not built to adapt themselves to personal needs. For example, assigning properties not envisioned by the database administrator or the software engineer such as "good music to listen to when I am in a bad mood" or "excellent sushi place for taking foreign guests" is difficult in most programs because schemas are often cast in stone by a compiler or database management system. Relationships between objects in the same program or different programs, such as "Bob is Mary's brother" or "this report is relevant to next week's meeting", are similarly difficult to specify, since programs either fail to expose their object models to each other, or their object models are not fine-grained enough. If computers cannot record connective meta-data-the "glue" we use for keeping track of things-information overload will eventually prevent users from taking full advantage of information technology.We claim that by using a semistructured data model, the system can capture the context and circumstances underlying information and not simply the information itself and thus help to elucidate the relevance of the information for the user and others. To demonstrate the efficacy of our semistructured data model (based on semantic networks) and explore its consequences to the user interface...

Supporting 64-bit global indices in Epetra and other Trilinos packages -- Techniques used and lessons learned

Jhurani, Chetan; Austin, Travis M.; Heroux, Michael A.; Willenbring, James M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 25/07/2013 Português
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The Trilinos Project is an effort to facilitate the design, development, integration and ongoing support of mathematical software libraries within an object-oriented framework. It is intended for large-scale, complex multiphysics engineering and scientific applications. Epetra is one of its basic packages. It provides serial and parallel linear algebra capabilities. Before Trilinos version 11.0, released in 2012, Epetra used the C++ int data-type for storing global and local indices for degrees of freedom (DOFs). Since int is typically 32-bit, this limited the largest problem size to be smaller than approximately two billion DOFs. This was true even if a distributed memory machine could handle larger problems. We have added optional support for C++ long long data-type, which is at least 64-bit wide, for global indices. To save memory, maintain the speed of memory-bound operations, and reduce further changes to the code, the local indices are still 32-bit. We document the changes required to achieve this feature and how the new functionality can be used. We also report on the lessons learned in modifying a mature and popular package from various perspectives -- design goals, backward compatibility, engineering decisions, C++ language features...

The Cyborg Astrobiologist: Porting from a wearable computer to the Astrobiology Phone-cam

Bartolo, Alexandra; McGuire, Patrick C.; Camilleri, Kenneth P.; Spiteri, Christopher; Borg, Jonathan C.; Farrugia, Philip J.; Ormo, Jens; Gomez-Elvira, Javier; Rodriguez-Manfredi, Jose Antonio; Diaz-Martinez, Enrique; Ritter, Helge; Haschke, Robert; Oeske
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/07/2007 Português
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We have used a simple camera phone to significantly improve an `exploration system' for astrobiology and geology. This camera phone will make it much easier to develop and test computer-vision algorithms for future planetary exploration. We envision that the `Astrobiology Phone-cam' exploration system can be fruitfully used in other problem domains as well.; Comment: 15 pages, 4 figures, accepted for publication in the International Journal of Astrobiology