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2009 ICSE Workshop on Automation of Software Test, AST 2009

作者： Neto, Arilo Claudio Dias Travassos, Guilherme Horta Federal University of Rio de Janeiro Systems Engineering and Computer Science Program COPPE/UFRJ P.O. Box 68511 21941-972 Rio de Janeiro RJ Brazil

ISBN: (纸本)9781424437436

The technical literature regarding Model-based Testing (MBT) has several techniques with different characteristics and goals available to be applied in software projects. Besides the lack of information regarding these techniques, they could be applied together in a software project aiming at improving the testing coverage. However, this decision needs to be carefully analyzed to avoid loss of resources in a software project. Based on this scenario, this paper proposes an approach with the purpose of supporting the unique or combined selection of MBT techniques for a given software project considering two aspects: the adequacy level between MBT techniques and the software project characteristics and impact of more than one MBT technique in some testing process variables. At the end, preliminary results of an experimental evaluation are presented.

关键词： Model checking

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Using modal logics to express and check global graph properties

Using modal logics to express and check global graph propert...

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作者： Benevides, Mario R.F. Schechter, L. Menasché Computer Science Department Systems and Computer Engineering Program Federal University of Rio de Janeiro Rio de Janeiro Brazil Systems and Computer Engineering Program Federal University of Rio de Janeiro Rio de Janeiro Brazil

Graphs are among the most frequently used structures in computer science. Some of the properties that must be checked in many applications are connectivity, acyclicity and the Eulerian and Hamiltonian properties. In this work, we analyze how we can express these four properties with modal logics. This involves two issues: whether each of the modal languages under consideration has enough expressive power to describe these properties and how complex (computationally) it is to use these logics to actually test whether a given graph has some desired property. First, we show that these properties are not definable in a basic modal logic or in any bisimulation-invariant extension of it, like the modal μ-calculus. We then show that it is possible to express some of the above properties in a basic hybrid logic. Unfortunately, the Hamiltonian and Eulerian properties still cannot be efficiently checked. In a second attempt, we propose an extension of CTL* with nominals and show that the Hamiltonian property can be more efficiently checked in this logic than in the previous one. In a third attempt, we extend the basic hybrid logic with the ↓ operator and show that we can check the Hamiltonian property with optimal (NP) complexity in this logic. Finally, we tackle the Eulerian property in two different ways. First, we develop a generic method to express edge-related properties in hybrid logics and use it to express the Eulerian property. Second, we express a necessary and sufficient condition for the Eulerian property to hold using a graded modal logic. © The Author 2009. Published by Oxford University Press. All rights reserved.

关键词： Model checking

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SpMT WaveCache: Exploiting Thread-Level Parallelism in WaveScalar

SpMT WaveCache: Exploiting Thread-Level Parallelism in WaveS...

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computer science and Information engineering, CSIE, WRI World Congress on FLAGGED

作者： Songwen Pei Baifeng Wu Min Du Gang Chen Leandro A.J. Marzulo Felipe M.G. Franca School of Computer Science Fudan University Shanghai China Systems Engineering and Computer Science Program COPPE Rio de Janeiro Brazil

Speculative multithreading (SpMT) increases the performance by means of executing multiple threads speculatively to exploit thread-level parallelism. By combining software and hardware approaches, we have improved the capabilities of previous WaveScalar ISA on the basis of transactional memory system for the WaveCache Architecture. Threads are extracted at the course of static compiling, and speculatively executed as a thread-level transaction that is supported by extra hardware components, such as thread-context-table (TCT) and thread-memory-history (TMH). We have evaluated the SpMT WaveCache with 6 real benchmarks from SPEC, Mediabench and Mibench. On the whole, the SpMT WaveCache outperforms superscalar architecture ranging from 2times to 3times, and great performance gains are achieved over original WaveCache and transactional WaveCache as well.

关键词： Yarn Parallel processing Multithreading Hardware computer science computer architecture Instruction sets Out of order program processors Protocols

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Porantim: An approach to support the combination and selection of Model-based Testing techniques

Porantim: An approach to support the combination and selecti...

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International Workshop on Automation of Software Test (AST)

作者： Arilo Claudio Dias Neto Guilherme Horta Travassos Systems Engineering and Computer Science Program-COPPE/UFRJ Federal University of Rio de Janeiro Rio de Janeiro Brazil

The technical literature regarding model-based testing (MBT) has several techniques with different characteristics and goals available to be applied in software projects. Besides the lack of information regarding these techniques, they could be applied together in a software project aiming at improving the testing coverage. However, this decision needs to be carefully analyzed to avoid loss of resources in a software project. Based on this scenario, this paper proposes an approach with the purpose of supporting the unique or combined selection of MBT techniques for a given software project considering two aspects: the adequacy level between MBT techniques and the software project characteristics and impact of more than one MBT technique in some testing process variables. At the end, preliminary results of an experimental evaluation are presented.

关键词： Software testing Automatic testing Software tools System testing Software quality programming Software systems Costs Context modeling systems engineering and theory

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A massively parallel hardware architecture for ray-tracing

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International Journal of High Performance systems Architecture 2009年第1期2卷 26-34页

作者： Nery, A.S. Nedjah, N. França, F.M.G. Computer Architecture and Microelectronics Laboratory Systems Engineering and Computer Science Program COPPE P.O. Box 68511 21941-972 Rio de Janeiro Brazil Department of Electronics Engineering and Telecommunications Faculty of Engineering Universidade do Estado do Rio de Janeiro Rua Sao Francisco Xavier 524 Sala 5145-F Maracana 20.550-900 Rio de Janeiro RJ Brazil Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil Department of Electronics Engineering and Telecommunications Faculty of Engineering State University of Rio de Janeiro Brazil Brazil

Real time performance of non-interactive rendering of three-dimensional scenes is usually unachievable. Ray tracing is one of the methods used for rendering such scenes. The performance achieved by a sequential software-based implementation of ray tracing is far from satisfactory. In contrast, many parallel implementations of ray tracing have been enabling real time performance, as the underlying algorithm can be massively parallelised. Thus, it is expected that a custom parallel design in hardware is likely to achieve the acceptable performance standards. In this paper, we propose a hardware architecture, which we call GridRT, capable of dealing with the main desirable features of ray tracing, such as shadows and reflections effects, imposing low requirements in terms of silicon area while achieving acceptable performance in terms of rendering time. This architecture achieves is efficient yet compact as it explores the massive parallelism offered by the intrinsic structure of the algorithm. The design exploits the usage the spatial data structure of regular grids. Copyright © 2009 Inderscience Enterprises Ltd.

关键词： Ray tracing

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On using grid of collocated APs to improve performance of wireless VoD systems

On using grid of collocated APs to improve performance of wi...

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5th International Latin American Networking Conference, LANC 2009

作者： De Pinho, Leonardo Bidese De Amorim, Claudio Luis Computer Engineering - Campus Bage UNIPAMPA - Federal University of Pampa P.O. Box 07 Bage RS 96400-970 Brazil COPPE - Systems Engineering Program UFRJ - Federal University of Rio de Janeiro P.O. Box 68.511 Rio de Janeiro RJ 21941-972 Brazil

ISBN: (纸本)9781605587752

In previous work we showed that Collocated Wireless Access Points coupled with appropriate management of their non-overlapping channels could be used for building Scalable Wireless Video-On-Demand (SWVoD) systems within a limited covered area. In this paper, we introduce the Grid of collocated Access Points or simply GAPS, a novel approach that uses clusters of Collocated Access Points as the basic blocks to efficiently build SWVoD systems for a wider covered area. In GAPS, each basic block is responsible for a distinct part of the covered area and the amount of APs per block can be set either statically or dynamically depending on the client concentration pattern (CCP). We present in details the framework of GAPS and report simulated performance results that indicated that GAPS could significantly decrease the blocking rate of video requests in comparison with previous design based on fixed distribution of basic blocks. In addition, GAPS had the advantage of sustaining the lower blockage rate over larger covered areas. Also, we showed that the higher setup cost of dynamic grids was fully compensated by handling changes on CCP much better than the static scheme so that GAPS could generate a higher monthly net income according to our cost metric. Copyright 2009 ACM.

关键词： Video on demand

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Impact of region-based faults on the connectivity of wireless networks

Impact of region-based faults on the connectivity of wireles...

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Annual Allerton Conference on Communication, Control, and Computing

作者： Arunabha Sen Sujogya Banerjee Pavel Ghosh Shahrzad Shirazipourazad Computer Science and Engineering Program School of Computing Informatics and Decision Systems Engineering Arizona State University Tempe AZ USA

ISBN: (纸本)9781424458707

The last few years have seen considerable interest in the wireless networking research community in analyzing the connectivity of wireless ad-hoc networks formed by a set of nodes distributed in a two dimensional plane (deployment area) with a (i) uniform probability density function and (ii) uniform transmission range. Although several important and interesting results are known in this domain, most of the connectivity studies consider a fault-free scenario where all nodes are available for network formation and do not consider failures among nodes caused by one reason or another. In very few studies where faults are considered, they are usually considered to be random in nature, i.e., the probability of a node failing is independent of its location in the deployment area. However, such fault scenario is inadequate to capture many realistic situations where the faulty nodes are spatially correlated. This is particularly true in combat environment where an enemy bomb can destroy a subset of nodes confined to a region. In this paper we investigate the impact of region-based faults on the connectivity of wireless networks. Through analysis and simulation, we provide results relating the probability of a network being connected as transmission range and the size of fault-region are varied. If d min (G) denotes the minimum node degree of the network, we provide the analytical expression for P(d min (G) ¿ k), which represents the probability of the minimum node degree being at least k, for k = 1. Moreover, we compute P(¿(G) ¿ k), where ¿(G) represents the connectivity of the graph G formed by the distribution of nodes in the deployment area and examine the relationship between P(d min (G) ¿ k) and P(¿(G) ¿ k) when k = 1.

关键词： Wireless networks Distributed computing Weapons Analytical models computer science computer networks Informatics systems engineering and theory Ad hoc networks Probability density function

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Comparison of threshold selection methods for microarray gene co-expression matrices

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BMC Research Notes 2009年第1期2卷 1-6页

作者： Borate, Bhavesh Chesler, Elissa Langston, Michael Saxton, Arnold Voy, Brynn Genome Science and Technology Program University of Tennessee Knoxville TN United States Department of Electrical Engineering and Computer Science University of Tennessee Knoxville TN United States Oak Ridge National Laboratory Systems Genetics Group Biosciences Division Oak Ridge TN United States Department of Animal Science University of Tennessee Knoxville TN United States

Background. Network and clustering analyses of microarray co-expression correlation data often require application of a threshold to discard small correlations, thus reducing computational demands and decreasing the number of uninformative correlations. This study investigated threshold selection in the context of combinatorial network analysis of transcriptome data. Findings. Six conceptually diverse methods - based on number of maximal cliques, correlation of control spots with expressed genes, top 1% of correlations, spectral graph clustering, Bonferroni correction of p-values, and statistical power - were used to estimate a correlation threshold for three time-series microarray datasets. The validity of thresholds was tested by comparison to thresholds derived from Gene Ontology information. Stability and reliability of the best methods were evaluated with block bootstrapping. Two threshold methods, number of maximal cliques and spectral graph, used information in the correlation matrix structure and performed well in terms of stability. Comparison to Gene Ontology found thresholds from number of maximal cliques extracted from a co-expression matrix were the most biologically valid. Approaches to improve both methods were suggested. Conclusion. Threshold selection approaches based on network structure of gene relationships gave thresholds with greater relevance to curated biological relationships than approaches based on statistical pair-wise relationships. © 2009 Saxton et al;licensee BioMed Central Ltd.

关键词： Spectral Cluster Maximal Clique Threshold Estimate Biological Relationship Spectral Graph

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A neuromorphic head direction cell system

A neuromorphic head direction cell system

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IEEE International Symposium on Circuits and systems (ISCAS)

作者： Tarek M. Massoud Timothy K. Horiuchi Electrical and Computer Engineering Department Institute of Systems Research Neuroscience and Cognitive Science Program University of Maryland College Park MD USA

ISBN: (纸本)9781424438273

The head direction (HD) cell system in the brain of mammals is thought to be part of the neural circuitry supporting their spatial navigation capabilities. In this paper we present a neuromorphic VLSI system that mimics the operation of the HD system. Relying on spiking neurons and attractor dynamics, this system can be used to represent and retain the current estimate of head orientation in the environment and integrate angular velocity to update this estimate. The presented system is a first step towards more general odometry systems that could be used for modeling biological navigation systems.

关键词： Neuromorphics Neurons High definition video Navigation Very large scale integration Biological system modeling Brain Neuroscience Cognitive science Educational institutions

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Dynamic screen division for load balancing the raycasting of irregular data

Dynamic screen division for load balancing the raycasting of...

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IEEE International Conference on Cluster Computing

作者： Bernardo B. Labronici Cristiana Bentest Lucia Maria A. Drummond Ricardo Farias Computer Science Department Federal Fluminense University Niterói RJ Brazil Department of System Engineering State University of Rio de Janeiro Rio de Janeiro RJ Brazil System Engineering and Computer Science Program-COPPE Centro de Tecnologia Rio de Janeiro RJ Brazil

Parallel rendering algorithms usually suffer from high load imbalance during execution, due to the irregular nature of the datasets. In this paper, we propose a new load balancing scheme for tile-based parallel rendering that includes strategies for load estimation, tile decomposition and tile assignment. The load estimation strategy computes the rendering cost for each pixel, and uses it as a prediction for the next frame. The tile decomposition strategy adaptively divides the screen into tiles based on the computed costs, until an evenly tile partition is achieved. The tile assignment strategy distributes the tiles among rendering processors, based on a 2-optimal scheduling. Experimental results show that our scheme achieves significant performance gains by reducing the load imbalance when compared to the traditional tile subdivision and static random distribution schemes.

关键词： Load management Tiles Rendering (computer graphics) Concurrent computing Parallel processing computer science Costs Data visualization Data engineering systems engineering and theory

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