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International Conference on computer Supported Cooperative Work in Design

作者： Magdaleno, Andréa Magalhães Araujo, Renata Mendes De Werner, Cláudia Maria Lima System Engineering and Computer Science Program - COPPE/UFRJ Rio de Janeiro RJ Brazil PPGI - Graduate Program in Informatics - UNIRIO Rio de Janeiro RJ Brazil

ISBN: (纸本)9781457703874

Organizations have been relying on collaboration for productivity improvement and knowledge sharing. The first step to foster collaboration in organizations is to make it explicit. With this aim, the Collaboration Maturity Model (CollabMM) was proposed and evaluated. The lessons learned during model applications in previous work pointed out the need to review both the model and its evaluation instruments. A literature review also showed some improvement opportunities. Therefore, the objective of this work is to develop a roadmap to highlight the main opportunities of evolution in CollabMM. These opportunities will compose our research agenda in this topic and guide future work. © 2011 IEEE.

关键词： Productivity

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An extensible architecture for DTV middleware 11

An extensible architecture for DTV middleware

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Proceedings of the 9th European Conference on Interactive TV and Video

作者： Ghisi, Bruno Cavaler Siqueira, Frank Graduate Program in Computer Science - PPGCC Department of Informatics and Statistics - INE Federal University Os Santa Catarina - UFSC Florianópolis Brazil

ISBN: (纸本)9781450306027

The currently adopted specifications for Digital Television (DTV) middleware do not define the internal characteristics of their architecture. As a result, the existing middleware implementations are not as flexible, extensible and adaptable as they should be due to the adoption of a closely-coupled architecture. This paper proposes a modular architecture for DTV middleware, which allows easy extension and updating, providing a simple way to add new features to the middleware. This architecture is based on the OSGi framework and its software components, called bundles. A categorization of these bundles was proposed, based on different usage scenarios that were identified, according to industry time-to-market and innovation needs. Prototypes of the architecture and of bundles have been implemented, and tests performed with these prototypes show the feasibility of this approach. © 2011 ACM.

关键词： Digital television

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Beyond connectivity-new metrics to evaluate robustness of networks

Beyond connectivity-new metrics to evaluate robustness of ne...

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International Conference on High Performance Switching and Routing

作者： Banerjee, Sujogya Shirazipourazad, Shahrzad Ghosh, Pavel Sen, Arunabha Computer Science and Engineering Program School of Computing Informatics and Decision System Engineering Arizona State University Tempe AZ 85281 United States

ISBN: (纸本)9781424484560

Robustness or fault-tolerance capability of a network is an important design parameter in both wired and wireless networks. Connectivity of a network is traditionally considered to be the primary metric for evaluation of its fault-tolerance capability. However, connectivity (G) (for random faults) or region-based connectivity R(G) (for spatially correlated or region-based faults, where the faults are confined to a region R) of a network G, does not provide any information about the network state, (i.e., whether the network is connected or not) once the number of faults exceeds (G) or R(G). If the number of faults exceeds (G) or R(G), one would like to know, (i) the number of connected components into which G decomposes, (ii) the size of the largest connected component, (iii) the size of the smallest connected component. In this paper, we introduce a set of new metrics that computes these values. We focus on one particular metric called region-based component decomposition number (RBCDN), that measures the number of connected components in which the network decomposes once all the nodes of a region fail. We study the computational complexity of finding RBCDN of a network. In addition, we study the problem of least cost design of a network with a target value of RBCDN. We show that the optimal design problem is NP-complete and present an approximation algorithm with a performance bound of O(log K + 4log n), where n denotes the number of nodes in the graph and K denotes a target value of RBCDN. We evaluate the performance of our algorithm by comparing it with the performance of the optimal solution. Experimental results demonstrate that our algorithm produces near optimal solution in a fraction of time needed to find an optimal solution. © 2011 IEEE.

关键词： Approximation algorithms

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Minimum maximum-degree publish-subscribe overlay network design

Minimum maximum-degree publish-subscribe overlay network des...

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作者： Onus, Melih Richa, Andréa W. Department of Computer Engineering Bilkent University Ankara 06560 Turkey Computer Science and Engineering Program School of Computing Informatics and Decision Systems Engineering Arizona State University Tempe AZ 85281 United States

Designing an overlay network for publish/subscribe communication in a system where nodes may subscribe to many different topics of interest is of fundamental importance. For scalability and efficiency, it is important to keep the degree of the nodes in the publish/subscribe system low. It is only natural then to formalize the following problem: Given a collection of nodes and their topic subscriptions, connect the nodes into a graph that has least possible maximum degree in such a way that for each topic t, the graph induced by the nodes interested in t is connected. We present the first polynomial-time logarithmic approximation algorithm for this problem and prove an almost tight lower bound on the approximation ratio. Our experimental results show that our algorithm drastically improves the maximum degree of publish/subscribe overlay systems. We also propose a variation of the problem by enforcing that each topic-connected overlay network be of constant diameter while keeping the average degree low. We present three heuristics for this problem that guarantee that each topic-connected overlay network will be of diameter 2 and that aim at keeping the overall average node degree low. Our experimental results validate our algorithms, showing that our algorithms are able to achieve very low diameter without increasing the average degree by much. © 2011 IEEE.

关键词： Overlay networks

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A Study of NetCDF as an Approach for High Performance Medical Image Storage

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Journal of Physics: Conference Series 2012年第1期341卷

作者： Marcone Magnus Thiago Coelho Prado Aldo von Wangenhein Douglas D J de Macedo M A R Dantas Post-graduate Program in Computer Science Department of Informatics and Statistic Federal University of Santa Catarina Florianópolis SC - Brasil Post-graduate Program in Knowledge Engineering and Managemet Department of Knowledge Engineering Federal University of Santa Catarina Florianópolis SC - Brasil

The spread of telemedicine systems increases every day. The systems and PACS based on DICOM images has become common. This rise reflects the need to develop new storage systems, more efficient and with lower computational costs. With this in mind, this article discusses a study for application in NetCDF data format as the basic platform for storage of DICOM images. The study case comparison adopts an ordinary database, the HDF5 and the NetCDF to storage the medical images. Empirical results, using a real set of images, indicate that the time to retrieve images from the NetCDF for large scale images has a higher latency compared to the other two methods. In addition, the latency is proportional to the file size, which represents a drawback to a telemedicine system that is characterized by a large amount of large image files.

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Using memory access traces to map threads and data on hierarchical multi-core platforms

Using memory access traces to map threads and data on hierar...

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25th IEEE International Parallel and Distributed Processing Symposium, Workshops and Phd Forum, IPDPSW 2011

作者： Da Cruz, Eduardo Henrique Molina Alves, Marco Antonio Zanata Carissimi, Alexandre Navaux, Philippe Olivier Alexandre Ribeiro, Christiane Pousa Méhaut, Jean-François PPGC Graduate Program in Computer Science Institute of Informatics UFRGS Federal University of Rio Grande do Sul Porto Alegre RS Brazil INRIA Mescal Research Team LIG Laboratory Grenoble University France

ISBN: (纸本)9780769543857

In parallel programs, the tasks of a given application must cooperate in order to accomplish the required computation. However, the communication time between the tasks may be different depending on which core they are executing and how the memory hierarchy and interconnection are used. The problem is even more important in multi-core machines with NUMA characteristics, since the remote access imposes high overhead, making them more sensitive to thread and data mapping. In this context, process mapping is a technique that provides performance gains by improving the use of resources such as interconnections, main memory and cache memory. The problem of detecting the best mapping is considered NP-Hard. Furthermore, in shared memory environments, there is an additional difficulty of finding the communication pattern, which is implicit and occurs through memory accesses. This work aims to provide a method for static mapping for NUMA architectures which does not require any prior knowledge of the application. Different metrics were adopted and an heuristic method based on the Edmonds matching algorithm was used to obtain the mapping. In order to evaluate our proposal, we use the NAS Parallel Benchmarks (NPB) and two modern multi-core NUMA machines. Results show performance gains of up to 75% compared to the native scheduler and memory allocator of the operating system. © 2011 IEEE.

关键词： Cache memory

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An Approach Using Parallel Architecture to Storage DICOM Images in Distributed File System

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Journal of Physics: Conference Series 2012年第1期341卷

作者： Tiago S Soares Thiago C Prado M A R Dantas Douglas D J de Macedo Michael A Bauer Informatics and Statistic Department Federal University of Santa Catarina Florianpolis Brazil Post-Graduate Program of Knowledge Engineering and Management Federal University of Santa Catarina Florianpolis Brazil Department of Computer Science University of Western Ontario UWO London Canada

Telemedicine is a very important area in medical field that is expanding daily motivated by many researchers interested in improving medical applications. In Brazil was started in 2005, in the State of Santa Catarina has a developed server called the CyclopsDCMServer, which the purpose to embrace the HDF for the manipulation of medical images (DICOM) using a distributed file system. Since then, many researches were initiated in order to seek better performance. Our approach for this server represents an additional parallel implementation in I/O operations since HDF version 5 has an essential feature for our work which supports parallel I/O, based upon the MPI paradigm. Early experiments using four parallel nodes, provide good performance when compare to the serial HDF implemented in the CyclopsDCMServer.

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Basic Issues in Vector High Dimensional Model Representation

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AIP Conference Proceedings 2011年第1期1389卷 1143-1146页

作者： Burcu Tunga Metin Demiralp aIstanbul Technical University Faculty of Computer and Informatics Maslak 34469 Istanbul Turkey bIstanbul Technical University Informatics Institute Computational Science and Engineering Program Maslak 34469 Istanbul Turkey

A multivariate modelling may involve a set of multivariate functions. A vector valued function structure can be used to mathematically express the given problem and each multivariate function can be considered as an element of this vector. This work aims to construct a new approach representing the elements of this vector structure in terms of less‐variate functions to reduce the computational complexity. For this purpose, a new method based on the plain High Dimensional Model Representation (HDMR) philosophy is developed. The basic concepts of this method and several illustrative numerical implementations are given here.

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On connectivity of Airborne Networks in presence of region-based faults

On connectivity of Airborne Networks in presence of region-b...

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MILCOM, Military Communications Conference

作者： Shahrzad Shirazipourazad Pavel Ghosh Arunabha Sen Computer Science and Engineering Program School of Computing Informatics and Decision System Engineering Arizona State University USA

The U.S. Air Force is currently in the process of building an Airborne Network (AN), where the nodes are a set of heterogeneous, highly mobile, Airborne Networking Platforms (ANPs) - such as satellites, airplanes and unmanned aerial vehicles. Mobility pattern of nodes in a mobile network has significant impact on the coverage and connectivity properties of the network. The level of reliability needed for continuous operation of an AN may be difficult to achieve through a completely infrastructure-less mobile ad hoc networks. In an earlier paper, we proposed an architecture for an AN where a set of ANPs form the backbone of the AN. In this architecture, the ANPs may be viewed as mobile base stations with predictable and well-structured flight paths and the combat aircrafts on a mission as mobile clients. In this paper we consider the AN scenario where a part of the network might not be operational due to enemy attack and/or jamming. We consider faults that are spatially correlated (or region-based), that is faults due to an enemy attack are confined to a region. The goal is to design a robust AN so that no matter which region in the deployment area fails and at what time, the surviving nodes of the network will remain connected and be able to communicate with each other. We propose an algorithm that finds the minimum transmission range necessary to ensure network connectivity irrespective of location of the fault region and the time of the failure.

关键词： Mobile communication computer architecture Mobile computing Reliability Orbits Aircraft Network topology

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Dynamic mortality simulation model incorporating risk indicators for cardiovascular diseases 11

Dynamic mortality simulation model incorporating risk indica...

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Simulation Winter Conference

作者： Jocimara S. Ferranti Paulo J. de Freitas Filho Postgraduate Program in Computer Science Department of Informatics and Statistics Federal University of Santa Catarina Florianopolis Santa Catarina Brazil

This article describes a dynamic-fuzzy simulation model and proposes an extension to it. The model represents a person's physiological capacity throughout life and simulates the occurrence of risk events from birth until death, including a representation of the process of recovering health after it has been impacted by a risk event. The expanded model incorporates cardiovascular risk factors in order to reproduce curves plotted from real mortality data from a specific population whose cause of death was cardiovascular diseases. By adjusting the parameters, it proved possible to reproduce mortality curves from populations with specific characteristics such as hypertension, obesity and physical activity levels. A simulation model that is capable of focusing on specific populations makes it possible to test alternative intervention designed to reduce the mortality caused by specific diseases, thereby contributing to improved quality-of-life for populations and to cost savings for both public and private health care systems.

关键词： Aging Mathematical model Equations Computational modeling Diseases Radio frequency

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