Página 6 dos resultados de 100905 itens digitais encontrados em 0.325 segundos

‣ Efficiency loss in market mechanisms for resource allocation

Johari, Ramesh, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 249 p.; 2084322 bytes; 2112281 bytes; application/pdf; application/pdf
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This thesis addresses a problem at the nexus of engineering, computer science, and economics: in large scale, decentralized systems, how can we efficiently allocate scarce resources among competing interests? On one hand, constraints are imposed on the system designer by the inherent architecture of any large scale system. These constraints are counterbalanced by the need to design mechanisms that efficiently allocate resources, even when the system is being used by participants who have only their own best interests at stake. We consider the design of resource allocation mechanisms in such environments. The analytic approach we pursue is characterized by four salient features. First, the monetary value of resource allocation is measured by the aggregate surplus (aggregate utility less aggregate cost) achieved at a given allocation. An efficient allocation is one which maximizes aggregate surplus. Second, we focus on market-clearing mechanisms, which set a single price to ensure demand equals supply. Third, all the mechanisms we consider ensure a fully efficient allocation if market participants do not anticipate the effects of their actions on market-clearing prices. Finally, when market participants are price anticipating, full efficiency is generally not achieved...

‣ Efficient algorithms for new computational models

Ruhl, Jan Matthias, 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 163 p.; 1188364 bytes; 1287306 bytes; application/pdf; application/pdf
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Advances in hardware design and manufacturing often lead to new ways in which problems can be solved computationally. In this thesis we explore fundamental problems in three computational models that are based on such recent advances. The first model is based on new chip architectures, where multiple independent processing units are placed on one chip, allowing for an unprecedented parallelism in hardware. We provide new scheduling algorithms for this computational model. The second model is motivated by peer-to-peer networks, where countless (often inexpensive) computing devices cooperate in distributed applications without any central control. We state and analyze new algorithms for load balancing and for locality-aware distributed data storage in peer-to-peer networks. The last model is based on extensions of the streaming model. It is an attempt to capture the class of problems that can be efficiently solved on massive data sets. We give a number of algorithms for this model, and compare it to other models that have been proposed for massive data set computations. Our algorithms and complexity results for these computational models follow the central thesis that it is an important part of theoretical computer science to model real-world computational structures...

‣ A large object-oriented virtual memory: grouping strategies, measurements, and performance

Stamos, James William
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 164 leaves; 13331480 bytes; 13331237 bytes; application/pdf; application/pdf
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by James William Stamos.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Bibliography: leaves 128-131.

‣ OverCite : a cooperative digital research library; Over Cite : a cooperative digital research library

Stribling, Jeremy
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 50 leaves; 2496775 bytes; 2497462 bytes; application/pdf; application/pdf
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CiteSeer is a well-known online resource for the computer science research community, allowing users to search and browse a large archive of research papers. Unfortunately, its current centralized incarnation is costly to run. Although members of the community would presumably be willing to donate hardware and bandwidth at their own sites to assist CiteSeer, the current architecture does not facilitate such distribution of resources. OverCite is a design for a new architecture for a distributed and cooperative research library based on a distributed hash table (DHT). The new architecture harnesses donated resources at many sites to provide document search and retrieval service to researchers worldwide. A preliminary evaluation of an initial OverCite prototype shows that it can service more queries per second than a centralized system, and that it increases total storage capacity by a factor of n/4 in a system of n nodes. OverCite can exploit these additional resources by supporting new features such as document alerts, and by scaling to larger data sets.; by Jeremy Stribling.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.; Includes bibliographical references (leaves 47-50).

‣ Extensions and enhancements to the iLab heat transfer project site

Saylor, David P. (David Patrick)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 74 p.
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The iLab Heat Transfer Project website started four years ago to enable web access to experiments related to movement of heat through transport processes. This thesis details improvements made to the site which extend and enhance the site prior to the project. Software improvements include giving teaching assistants the ability to add their entire class as users simultaneously and creating a method by which feedback data is stored as a full questionnaire instead of database entries. Hardware improvements include the addition of a webcam that streams video and audio of the experiment in real time and the integration of two new thermodynamic experiments complete with remote access. The final improvement is the administrator manual, which is intended to ease the burden on new staff members by bridging their knowledge with that of previous years.; by David P. Saylor.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, September 2005; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2004.; "September 5, 2005." "Copyright 1998."; Includes bibliographical references (p. 74).

‣ Declarative configuration applied to course scheduling

Yeung, Vincent S. (Vincent Shu Hang)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 84 p.
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This thesis describes a course scheduling system that models planning as a satisfiability problem in relational logic. Given a set of course requirements for a degree program, our system can find a schedule of courses that will complete these requirements. It supports a flexible XML format for expressing course requirements and also handles additional user-specific constraints, such as requirements that certain courses be taken at particular times. Various optimizations were included in the translation to relational logic to improve the performance of our system and the quality of its results. We ran experiments on our system using degree programs from the Department of Electrical Engineering and Computer Science at MIT as input, and found that our approach is competitive with conventional planners.; by Vincent S. Yeung.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.; Includes bibliographical references (p. 83-84).

‣ A Lorentz-force actuated controllable needle-free drug delivery system

Hemond, Brian D. (Brian David Thomson)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 145 leaves
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The advantages of delivering injections via needle-free methods are numerous. However, conventional methods for needle-free injection lack sufficient control over depth of penetration and shape of injection. Thus, a needle-free injector was designed, constructed, and tested, using a controllable linear Lorentz-force actuator. This actuator allows rapid control of the injection pressure during injections. Using this device, precise control over delivery parameters can be achieved. In addition, several portable power systems for this injector were developed, allowing the energy-intensive needle-free injector to be used in the field. The injector design was tested for repeatability and use for both in-vitro and in-vivo testing on murine tissue using a bacterial collagenase.; by Brian D. Hemond.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2004; and, (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2006.; Includes bibliographical references (leaves 89-90).

‣ Numerical methods for identification of induction motor parameters

Shaw, Steven Robert, 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 223 leaves
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by Steven Robert Shaw.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; and, (Elec. E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.; Earlier issued with only one degree specified: M.Eng. M. Eng. degree awarded in 1997; Elec. E. degree awarded in 2000.; Includes bibliographical references (leaves 221-223).

‣ Computer Science (CS) Home

Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
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Department of Computer Science at the Naval Postgraduate School webpage.; Educating our Computer Science masters and doctoral students is the most important activity of the department. Our central focus is equipping our students to perform well as technical leaders in the world they will face after graduation. Complexity and change are dominant characteristics of that world. We develop technical leaders by teaching a principles-based curriculum, around which we build practices for managing complexity and innovation. We conduct an extensive research program that directly enhances national security by increasing the effectiveness of the armed forces of the United States and its allies.

‣ Outphase power amplifiers in OFDM systems; Outphase power amplifiers in Orthogonal Frequency Division Multiplexing systems

Phạm, Anh D., 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 95 leaves; 6070448 bytes; 6075404 bytes; application/pdf; application/pdf
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A trade-off between linearity and efficiency exists in conventional power amplifiers. The outphase amplifying concept overcomes this trade-off by enabling the use of high efficiency, non-linear power amplifiers for linear amplification. An amplitude modulated signal is first decomposed into two constant amplitude, phase modulated signals that can be amplified using two high efficiency switching power amplifiers. The two outputs are then recombined to restore the original amplitude modulated signal. In this manner, an outphase power amplifier can simultaneously achieve high efficiency and good linearity. This thesis investigates the capability of the outphase amplifying technique in modern wireless communication. First, a digital amplitude-to-phase conversion scheme is proposed to facilitate the outphase decomposition. By taking advantage of the available computational power in current digital technology, the amplitude-to-phase conversion can be implemented with both accuracy and efficiency in the digital domain. A proof-of-concept outphase power amplifier is fabricated using the IBM 7WL SiGe BiCMOS process technology.; (cont.) The test chip includes two class-E power amplifiers and the first 5.8GHz fully integrated Wilkinson power combiner. The low-loss integrated combiner allows efficient outphase recombining while providing the necessary input isolation for a robust outphase power amplifier. The outphase power amplifier achieves an efficiency of 47% at the maximum output power of 18.5 dBm. For an input Orthogonal Frequency Division Multiplexing (OFDM) signal of 32 sub-channels of 64-QAM...

‣ Applying integer programming techniques to find minimum integer weights of voting games

Strauss, Aaron B., 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 76 p.; 3809395 bytes; 3817408 bytes; application/pdf; application/pdf
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Using concepts from computer science and mathematics I develop three algorithms to find the minimum integer weights for voting games. Games with up to at least 17 players can be solved in a reasonable amount of time. First, coalitions are mapped to constraints, reducing the problem to constraint optimization. The optimization techniques used are Gomory's all-integer simplex algorithm and a variant of the popular integer programming method branch and bound. Theoretical results include that minimum integer weights are not unique and a confirmation of a prior result that minimum integer weights are proportional to a priori seat share. Thus, these algorithms can be useful for researchers evaluating the differences between proportional bargaining models and formateur models. The running times of the different algorithms are contrasted and analyzed for potential improvements.; by Aaron B. Strauss.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 73-76).

‣ Designing customizable end user applications using semantic technologies to improve information management

Watugala, Sumudu Weerakoon
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 155 leaves
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Personalization capabilities in computer applications attempt to better meet the needs of individuals. The more traditional and widespread paradigm in application design is that the user should adapt to the available application. This requires that the individual user's task be sliced and molded to fit the dimensions offered by an inflexible, monolithic application. It is desirable to have an application that can be shaped to fit each individual user's dynamic needs. However, it is important that this is done in an intuitive and unobtrusive way. In this thesis, we design and evaluate a personalizable application developed to aid life science researchers in their work. We designed the application in Haystack, a platform for developing semantic applications and user interfaces. The application gave the user flexibility in personalizing the way in which information is organized and displayed, while giving users access to the tools necessary to perform their tasks. We selected researchers as the user group to focus on because of the inherent necessity in their work for originality and dynamic adaptation. Life sciences research was chosen as the domain due to its potential to benefit from the application of semantic technologies. We tested how users reacted and adapted to this application by conducting a formal user study.; by Sumudu Weerakoon Watugala.; Thesis (M. Eng.)--Massachusetts Institute of Technology...

‣ DAN-based string rewrite computational systems

Khodor, Julia, 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 97 p.; 9404973 bytes; 9404731 bytes; application/pdf; application/pdf
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We describe a DNA computing system called programmed mutagenesis. prove that it is universal, and present experimental results from a prototype computation. DNA is a material with important characteristics, such as possessing all the information necessary for self-reproduction in the presence of appropriate enzymes and components, simple natural evolution mechanism, and miniature scale, all of which make it an attractive substrate for computation. For computer science, using single DNA molecules to represent the state of a computation holds the promise of a new paradigm of composable molecular computing. For biology, the demonstration that DNA sequences could guide their own evolution under computational rules may have implications as we begin to unravel the mysteries of genome encoding. Programmed mutagenesis is a DNA computing system that uses cycles of DNA annealing, ligation, and polymerization to implement programmatic rewriting of DNA sequences. We report that programmed mutagenesis is theoretically universal by showing how Minsky's 4-symbol 7-state Universal Turing Machine can be implemented using a programmed mutagenesis system. Each step of the Universal Turing Machine is implemented by four cycles of programmed mutagenesis...

‣ Exploration of the Gap Between Computer Science Curriculum and Industrial I.T Skills Requirements

Ayofe, Azeez Nureni; Ajetola, Azeez Raheem
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/08/2009 Português
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This paper sets out to examine the skills gaps between the industrial application of Information Technology and university academic programmes (curriculum). It looks at some of the causes, and considers the probable solutions for bridging the gap between them and suggests the possibilities of exploring a new role for our universities and employers of labor. It also highlights strategies to abolish the misalignment between university and industry. The main concept is to blend the academic rigidity with the industrial relevance.; Comment: 10 pages IEEE Format, International Journal of Computer Science and Information Security, IJCSIS 2009, ISSN 1947 5500, Impact factor 0.423, http://sites.google.com/site/ijcsis/

‣ Discovering Links for Metadata Enrichment on Computer Science Papers

Schaible, Johann; Mayr, Philipp
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 15/12/2012 Português
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At the very beginning of compiling a bibliography, usually only basic information, such as title, authors and publication date of an item are known. In order to gather additional information about a specific item, one typically has to search the library catalog or use a web search engine. This look-up procedure implies a manual effort for every single item of a bibliography. In this technical report we present a proof of concept which utilizes Linked Data technology for the simple enrichment of sparse metadata sets. This is done by discovering owl:sameAs links be- tween an initial set of computer science papers and resources from external data sources like DBLP, ACM and the Semantic Web Conference Corpus. In this report, we demonstrate how the link discovery tool Silk is used to detect additional information and to enrich an initial set of records in the computer science domain. The pros and cons of silk as link discovery tool are summarized in the end.; Comment: 22 pages, 4 figures, 7 listings, presented at SWIB12

‣ Maps of Computer Science

Fried, Daniel; Kobourov, Stephen G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/04/2013 Português
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We describe a practical approach for visual exploration of research papers. Specifically, we use the titles of papers from the DBLP database to create what we call maps of computer science (MoCS). Words and phrases from the paper titles are the cities in the map, and countries are created based on word and phrase similarity, calculated using co-occurrence. With the help of heatmaps, we can visualize the profile of a particular conference or journal over the base map. Similarly, heatmap profiles can be made of individual researchers or groups such as a department. The visualization system also makes it possible to change the data used to generate the base map. For example, a specific journal or conference can be used to generate the base map and then the heatmap overlays can be used to show the evolution of research topics in the field over the years. As before, individual researchers or research groups profiles can be visualized using heatmap overlays but this time over the journal or conference base map. Finally, research papers or abstracts easily generate visual abstracts giving a visual representation of the distribution of topics in the paper. We outline a modular and extensible system for term extraction using natural language processing techniques...

‣ A Comparison of On-Line Computer Science Citation Databases

Petricek, Vaclav; Cox, Ingemar J.; Han, Hui; Councill, Isaac G.; Giles, C. Lee
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/03/2007 Português
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This paper examines the difference and similarities between the two on-line computer science citation databases DBLP and CiteSeer. The database entries in DBLP are inserted manually while the CiteSeer entries are obtained autonomously via a crawl of the Web and automatic processing of user submissions. CiteSeer's autonomous citation database can be considered a form of self-selected on-line survey. It is important to understand the limitations of such databases, particularly when citation information is used to assess the performance of authors, institutions and funding bodies. We show that the CiteSeer database contains considerably fewer single author papers. This bias can be modeled by an exponential process with intuitive explanation. The model permits us to predict that the DBLP database covers approximately 24% of the entire literature of Computer Science. CiteSeer is also biased against low-cited papers. Despite their difference, both databases exhibit similar and significantly different citation distributions compared with previous analysis of the Physics community. In both databases, we also observe that the number of authors per paper has been increasing over time.; Comment: ECDL 2005

‣ The Computing Research Repository: Promoting the Rapid Dissemination and Archiving of Computer Science Research

Halpern, Joseph Y.; Lagoze, Carl
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/12/1998 Português
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We describe the Computing Research Repository (CoRR), a new electronic archive for rapid dissemination and archiving of computer science research results. CoRR was initiated in September 1998 through the cooperation of ACM, LANL (Los Alamos National Laboratory) e-Print archive, and NCSTRL (Networked Computer Science Technical Research Library. Through its implementation of the Dienst protocol, CoRR combines the open and extensible architecture of NCSTRL with the reliable access and well-established management practices of the LANL XXX e-Print repository. This architecture will allow integration with other e-Print archives and provides a foundation for a future broad-based scholarly digital library. We describe the decisions that were made in creating CoRR, the architecture of the CoRR/NCSTRL interoperation, and issues that have arisen during the operation of CoRR.; Comment: Submission to ACM DL99

‣ Informática na Educação Especial; Computer Science within Social Education

Almeida, Amélia Leite de
Fonte: Universidade de São Paulo. Escola de Comunicações e Artes Publicador: Universidade de São Paulo. Escola de Comunicações e Artes
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; Formato: application/pdf
Publicado em 30/12/2002 Português
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E nosso propósito neste artigo expor aspectos relativos a Educaçáo Especial e discutir alguns princípios educacionais fundamentais no uso da informatica na Educação Especial, considemndo a irnportancia das novas tecnologias e a necessidade de se trabalhar com computadores dentro de uma pedagogia que priorize a reestruturação de conhecimentos e não o desenvolvimento de uma tecnologia de reproduçáo de informaçóes. O trabalho com Informática nos conduz a uma metodologia por meio da qual toda educação é um processo especial, e o educador deve apresentar um novo perfil perante os recursos tecnológioos e as novas tecnologias em comunicação.; It is our purpose in this article to present questions related to Special Education and to discuss some fundamental educational principles in the use of Computer Science within Special Education. Due to the importante of the new technologies and lhe need ot working just with oomputers in pedagogy the restructuring of knowledge and not, the development of a technology for the reproduction o? information need to be considered,.The work with Computer Science leads us to a methodology through which all education is seen as a special process, and the educator presents a new profile in the face of technological resouroes and of the new technologies in communication.

‣ A Detailed Study of the Computer Science Degree at the Central University of Venezuela: Towards a New Curriculum Design

Villapol,Maria E.; Castillo,Zenaida; Acosta,Alecia E.; Gómez,Marco; Bottini,Adrian; Carmona,Rhadamés; Juhasz,Harun; Acosta,Carlos
Fonte: CLEI Electronic Journal Publicador: CLEI Electronic Journal
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 Português
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Abstract- The Central University of Venezuela, as part of its efforts for adapting its academic offer to national and international needs, is conducting a project to review, evaluate and modify the Computer Science curriculum, in order to form the professional required by the country. In this paper we present the results of the first stage of the project: an assessment of the Computer Science curriculum based on the use of various data collection instruments used to determine the professor, student and graduates perception of the program as well as deficiencies and potential of our graduates, according to the companies and organizations that hire them. The results show that there exist a gap between the perception of our professors about the program and the opinion of the employers. We also present information about student performance during the last decade, which is an input to the next stage of the program redesign.