LUTS: A lightweight user-level transaction scheduler

Software Transactional Memory (STM) systems have poor performance under high contention scenarios. Since many transactions compete for the same data, most of them are aborted, wasting processor runtime. Contention management policies are typically used to avoid that, but they are passive approaches as they wait for an abort to happen so they can take action. More proactive approaches have emerged, trying to predict when a transaction is likely to abort so its execution can be delayed. Such techniques are limited, as they do not replace the doomed transaction by another or, when they do, they rely on the operating system for that, having little or no control on which transaction should run. In this paper we propose LUTS, a Lightweight User-Level Transaction Scheduler, which is based on an execution context record mechanism. Unlike other techniques, LUTS provides the means for selecting another transaction to run in parallel, thus improving system throughput. Moreover, it avoids most of the issues caused by pseudo parallelism, as it only launches as many system-level threads as the number of available processor cores. We discuss LUTS design and present three conflict-avoidance heuristics built around LUTS scheduling capabilities. Experimental results, conducted with STMBench7 and STAMP benchmark suites, show LUTS efficiency when running high contention applications and how conflict-avoidance heuristics can improve STM performance even more. In fact, our transaction scheduling techniques are capable of improving program performance even in overloaded scenarios. © 2011 Springer-Verlag.

Virtual instrumentation: A practical approach to control and supervision process

This work describes a control and supervision application takes into account the virtual instrumentation advantages to control and supervision industrial manufacturing stations belonging to the modular production system MPS® by Festo. These stations integrate sensors, actuators, conveyor belt and other industrial elements. The focus in this approach was to replace the use of programmable logic controllers by a computer equipped with a software application based on Labview and, together, performs the functions of traditional instruments and PLCs. The manufacturing stations had their processes modeled and simulated in Petri nets. After the models were implemented in Labview environment. Tests and previous similar works in MPS® installed in Automation Laboratory, at UNESP Sorocaba campus, showed the materials and methods used in this work allow the successful use of virtual instrumentation. The results indicate the technology as an advantageous approach for the automation of industrial processes, with gains in flexibility and reduction in project cost. © 2011 IEEE.

Domain reduction using GRASP construction phase for transmission expansion planning problem

This paper proposes a new strategy to reduce the combinatorial search space of a mixed integer linear programming (MILP) problem. The construction phase of greedy randomized adaptive search procedure (GRASP-CP) is employed to reduce the domain of the integer variables of the transportation model of the transmission expansion planning (TM-TEP) problem. This problem is a MILP and very difficult to solve specially for large scale systems. The branch and bound (BB) algorithm is used to solve the problem in both full and the reduced search space. The proposed method might be useful to reduce the search space of those kinds of MILP problems that a fast heuristic algorithm is available for finding local optimal solutions. The obtained results using some real test systems show the efficiency of the proposed method. © 2012 Springer-Verlag.

Teaching and learning data structures supported by computers: An experiment using CADILAG tool

This paper aims to present the use of a learning object (CADILAG), developed to facilitate understanding data structure operations by using visual presentations and animations. The CADILAG allows visualizing the behavior of algorithms usually discussed during Computer Science and Information System courses. For each data structure it is possible visualizing its content and its operation dynamically. Its use was evaluated an the results are presented. © 2012 AISTI.

Optimal reactive power dispatch using stochastic chance-constrained programming

Deterministic Optimal Reactive Power Dispatch problem has been extensively studied, such that the demand power and the availability of shunt reactive power compensators are known and fixed. Give this background, a two-stage stochastic optimization model is first formulated under the presumption that the load demand can be modeled as specified random parameters. A second stochastic chance-constrained model is presented considering uncertainty on the demand and the equivalent availability of shunt reactive power compensators. Simulations on six-bus and 30-bus test systems are used to illustrate the validity and essential features of the proposed models. This simulations shows that the proposed models can prevent to the power system operator about of the deficit of reactive power in the power system and suggest that shunt reactive sourses must be dispatched against the unavailability of any reactive source. © 2012 IEEE.

Programação de horários usando um algoritmo de busca em vizinhança variável

Pós-graduação em Engenharia Elétrica - FEIS

Recursos tecno-metodológicos para descrição e recuperação de informações na Web

Pós-graduação em Ciência da Informação - FFC

O processo de análise de assunto na catalogação de documentos: a perspectiva sociocognitiva do catalogador em contexto de biblioteca universitária

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Extração de contornos de telhados usando princípios de Snake Balloon

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Implementação de uma plataforma HW/SW para automação industrial, utilizando hardware reconfigurável com processador NIOS II em conformidade com o padrão IEEE 1451

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sistema multiagente web semântico para gestão de conteúdos educacionais

Pós-graduação em Ciência da Computação - IBILCE

Sintaxe e semântica de registros bibliográficos: princípios para a conversão de registros analógicos para o formato MARC21 bibliográfico: Scan for MARC

The research presents as its central theme the study of the bibliographic record conversion process. The object of study is framed by an understanding of analogic bibliographic record conversion to the Bibliograhpic MARC21 format, based on a syntactic and semantic analysis of records described according to descriptive metadata structure standards and content standards. The objective of this research the objective is to develop a theoretical-conceptual model of syntactic and semantic of bibliographic records, from Linguistic studies of Saussure and Hjelmslev of manifestations of human language, which subsidizes the development of a computacional interpreter, focused to the conversion of bibliographic records to MARC21 Bibliographic Format, which can be confirmed both the semantic value of the informational resource represented as the reliability of the representation. Given the aforementioned objectives, the methodological trajectory of the research is based on the qualitative approach, of an exploratory, descriptive and experimental nature, and with recourse to the literature. Contributions on the theoretical plane can be envisaged regarding the development of questions inherent to the syntactic and semantic aspects of bibliographic records, and by involving, at the same time, interdisciplinarity between Information Science, Computer Science and Linguistics. Contributions to the practical field are identified by the fact the study covers the development of the Scan for MARC, a computational interpreter that can be adopted by any institution that wishes to use the conversion procedure for bibliographic record databases to the MARC21 Bibliographic Format from description and visualization schemes of bibliographic records (AACR2r and ISBD), an aspect of the research which is considered innovative.

Sistema de recomendação de produtos online baseado em palavras-chave

This project aims to explore the many methods used for the development of recommendation systems to user ’ s items and apply the content - based recommendation method on a prototype system whose purpose is to recommend books to users. This paper exposes the most popular methods for creating systems capable of providing items (products) according to user preferences, such as collaborat ive filtering and content - based. It also point different techniques that can be applied to calculate the similarity between two entities, for items or users, as the Pearson ’s method, calculating the cosine of vectors and more recently, a proposal to use a Bayesian system under a Dirichlet distribution. In addition, this work has the purpose to go through various points on the design of an online application, or a website, dealing not only oriented algorithms issues, but also the definition of development to ols and techniques to improve the user’s experience. The tools used for the development of the page are listed, and a topic about web design is also discussed in order to emphasize the importance of the layout of the application. At the end, some examples of recommender systems are presented for curiosity , learning and research purposes

Análise da dinâmica do uso da terra e sua interferência em enchentes na área urbana do município de Americana (SP)

Due to an intense process of population growth and urban density in Americana (SP), mainly due to the development of the local textile industry after 1970, there was, concomitant to the occupation of the margin of rivers and streams, soil sealing that increased the level of superficial runoff, triggering frequent floods. Based on the analysis of these processes we investigate the conditions of one densely urbanized area of the county, the Córrego do Parque, in three time series, 1977, 1996 and 2008. Taking as the starting the characterization and spatial distribution of landscape physiography, we prepared thematic letters and synthetic maps digital scale 1:10,000 from photointerpretation of aeroframes. The thematic maps were produced by scanning with subsequent edition using the software Auto-Cad Map. Checking the data and of geographic coordinates with GPS (Global Positioning System). Regarding land use classes, we used the description of the Soil Conservation Service (1975) which allowed us to get the Curve Number parameter, which will be used in hydrologic modeling for verification of flooding (Tucci, 1989). For the process of hydrologic modeling, we used models based on Methodology Object Oriented Modeling Applied to Water Resource Systems, Viegas Filho (1999), using the computer program called IPHS1, which uses models of the Soil Conservation Service (SCS , 2004), for conversion of rainfall-runoff and the spread of excessive rain. The results indicate that increased waterproofing generated by the change in use and occupation over the past decades promoted the increased surface runoff and drainage system overload, increasing the intensity of floods

Gerenciamento de transação e mecanismo de serialização baseado em Snapshot

Pós-graduação em Ciência da Computação - IBILCE