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distributed Weighted Vertex Cover via Maximal Matchings

ACM TRANSACTIONS ON ALGORIthMS 2008年第1期5卷 1-12页

作者： Grandoni, Fabrizio Koenemann, Jochen Panconesi, Alessandro Univ Roma Tor Vergata Dipartimento Informat Sistemi & Produz I-00133 Rome Italy Univ Waterloo Dept Combinator & Optimizat Waterloo ON N2L 3G1 Canada Sapienza Univ Roma Dipartimento Informat I-00198 Rome Italy

In this article, we consider the problem of computing a minimum-weight vertex-cover in an n-node, weighted, undirected graph G = (V, E). We present a fully distributed algorithm for computing vertex covers of weight at most twice the optimum, in the case of integer weights. Our algorithm runs in an expected number of O(log n + log (W) over cap) communication rounds, where (W) over cap is the average vertex-weight. the previous best algorithm for this problem requires O(log n(log n+ log (W) over cap)) rounds and it is not fully distributed. For a maximal matching M in G, it is a well-known fact that any vertex-cover in G needs to have at least vertical bar M vertical bar vertices. Our algorithm is based on a generalization of this combinatorial lower-bound to the weighted setting.

关键词： Approximation algorithms distributed algorithms maximal matching vertex cover

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A new weighted centroid localization algorithm in wireless sensor networks

A new weighted centroid localization algorithm in wireless s...

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international conference on Computer and Information Technology (ICCIT)

作者： Yahya Forghani Toos Institute of Higher Education Mashhad Iran

Nodes in a sensor network are often randomly distributed. To assign measurements to locations, each node has to determine its own position. Algorithms for positioning in wireless sensor networks are classified into two groups: approximate and exact. In this paper, we propose a range-based approximate positioning approach which is almost the combination of WCL and EBTB. then, compare it with two other approximate positioning approaches (WCL with time complexity of O(n)) and EBTB with time complexity of O(n*n) and an exact positioning approach (QR Factorization with time complexity of O(n*n*n)). Finally, it will be shown that EWCL (with time complexity of O(n*n)) is the best localization algorithm with respect to the three other localization algorithms when the noise is high and its accuracy is close to the accuracy of QR when the noise is medium.

关键词： Wireless sensor networks Global Positioning System Position measurement Intelligent sensors GSM Computer networks distributed computing Information technology Computer science education Electronic components

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Efficient Strategies for Workload Distribution in Heterogeneous computing Systems

Efficient Strategies for Workload Distribution in Heterogene...

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IEEE international conference on Computational Science and Engineering Workshops (CSEWORKSHOPS)

作者： Jean Marcos Laine Edson Toshimi Midorikawa Laboratory of Architecture and High Performance Computing Department of Computer Engineering and Digital Systems Polytechnic School University of São Paulo Sao Paulo Brazil

ISBN: (纸本)9780769532578

An effective workload distribution has a prime rule on reducing the total execution time of a parallel application on heterogeneous environments, such as computational grids and heterogeneous clusters. this paper presents two approaches to workload distribution based on analytical models developed to performance prediction of parallel applications, named VRP and VRP-SS. the workload is distributed based on relative performance ratios, obtained by analytical models constructed according to the rules described in the PEMPIs methodology. In the experimental tests we evaluated the strategies and compared them using MPI applications. the results showed the efficiency of our strategies by reducing the total execution time and improving the workload balance.

关键词： Load management Analytical models Indexes Processor scheduling Computational modeling Ethernet networks SDRAM

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LCRACO - A new load and congestion controlled routing based on ant colony optimization

LCRACO - A new load and congestion controlled routing based ...

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international conference on Computer and Information Technology (ICCIT)

作者： Rituparna Chaki Ditipriya Sinha West Bengal University of Technology West Bengal India Calcutta Institute of Engineering and Management West Bengal India

Designing efficient, cost-effective routing solutions for the infrastructure-less MANETs remains a daunting task till date. A proven optimization technique, the Ant colony optimization has been used in this paper to find the optimum in terms of the shortest route in a MANET. Special attention has been given to the load balancing and congestion control in the network. the simulated performance graphs show an improved congestion control for the proposed routing protocol.

关键词： Ant colony optimization Mobile ad hoc networks Routing protocols Bridges Clustering algorithms Broadcasting Internet distributed computing Control systems Load management

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A calculus for composite authorities' policy derivation in shared domains of pervasive computing environments

A calculus for composite authorities' policy derivation in s...

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international conference on Computer and Information Technology (ICCIT)

作者： Morteza Amini Rasool Jalili Department of Computer Engineering Sharif University of Technology Tehran Iran

the decentralized security management in a pervasive computing environment, requires apportioning the environment into several security domains. In each security domain, an administrator (we call it authority) is responsible for specifying the security policies of the domain. Overlapping of security domains results in the requirement of cooperative security management in the shared/ overlapping domains. To satisfy this requirement, we propose an abstract security model, as well as its supplementary calculus of composite authorities. the security model is based on deontic logic and is independent of the domains' heterogeneity. the model's policy language (we call it MASL) enables multiple authorities to specify their domain policies, including obligations and authorizations. Our proposed calculus of composite authorities, enables the security system to infer policy statements of composite authorities from the cooperating primitive authorities. the calculus offers three styles of cooperative administration including collaborative, disjunctive, and delegative administration. Abstraction and automated composite authorities' policy derivation are the main advantages of the proposed logical model.

关键词： Calculus Pervasive computing Authorization Access control distributed computing Computer security Environmental management Collaboration Logic programming Ontologies

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distributed control in Multi-Agent Systems: A preliminary model of autonomous MAV swarms

Distributed control in Multi-Agent Systems: A preliminary mo...

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international conference on Information Fusion

作者： Fabio Ruini Angelo Cangelosi Adaptive Behaviour and Cognition Research Group School of Computing Communications and Electronics University of Plymouth UK

this article focuses on the use of multi-agent systems for modelling of micro-unmanned aerial vehicles (MAVs) in a distributed control task. the task regards a search and destroy scenario in the context of security and urban counter-terrorism. In the simulations developed, a swarm composed of four autonomous flying robots, driven by an embodied neural network controller, has to approach a target deployed somewhere within the given environment. When close enough to the target, one of the aircraft needs to carry out a detonation in order to neutralize it. the controllers used by the MAVs evolve through a genetic algorithm. the preliminary results presented here demonstrate how the adaptive evolutionary approach can be successfully employed to develop controllers of this kind. the MAV swarms evolved in this way are in fact able to reach and hit the target, navigating through an obstacle-full environment. Further works on this model will focus on the development of a 3D physical simulator, in order to move towards the usage of MAVs with neural network controllers in real applicative urban scenarios.

关键词： Distance measurement Artificial neural networks Robots Encoding distributed control Unmanned aerial vehicles Aircraft

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Quality of Service Management for Web Service Compositions

Quality of Service Management for Web Service Compositions

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IEEE international conference on Computational Science and Engineering, CSE

作者： Diego Zuquim Guimarães Garcia Maria Beatriz Felgar de Toledo Institute of Computing University of Campinas São Paulo Brazil

Typically, scientific applications have to be distributed across computational grid infrastructures. these applications can use existent grid services. Service components in this kind of application may have different computational platforms that should interoperate. this interoperability is supported by the Web service technology. thus, currently, some Web service standards are used in several service-oriented grid infrastructures. the Web Services Business Process Execution Language (WS-BPEL) is an example of a standard that can be used in this context to support the definition of scientific workflows. However, its approach for building service compositions does not consider quality of service (QoS) issues. this paper proposes an approach for building service compositions according to QoS characteristics expressed using the Web services policy framework (WS-policy).

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An Anisotropic Diffusion Filtering Implementation to Execute in Parallel distributed Systems

An Anisotropic Diffusion Filtering Implementation to Execute...

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IEEE international conference on Computational Science and Engineering Workshops (CSEWORKSHOPS)

作者： Antonio C. Sobieranski Leandro Coser M.A.R. Dantas Aldo v. Wangenheim Eros Comunello LAPIX-Image Processing and Graphic Computing Lab The Cyclops Group Federal University of Santa Catarina Brazil LaPeSD-Distributed Systems Research Laboratory Federal University of Santa Catarina Brazil Graduate Program Applied Computer Science Universidade do Vale do Itajaí Brazil

ISBN: (纸本)9780769532578

In this paper, we present a parallelization of a filtering algorithm related to non-linear anisotropic diffusion, used to enhance the performance of an application in a parallel distributed system. the anisotropic diffusion is a well-established technique for image enhancement by means of diffusivity functions, which act as border attenuators. However, it requires a high computational cost when a large amount of data is used. the proposed implementation was parallelized considering both point-to-point and collective communications, adopting the MPI paradigm. Results from both approaches indicate that the proposed algorithm has reached interesting levels of performance (81% and 93% of efficiency, respectively) when compared to the execution of one process in a single computer node. In addition, our results indicate an enhancement of around 21% utilizing the collective communication strategy when compared to point-to-point communication.

关键词： Filtering Magnetic separation Anisotropic magnetoresistance Ions Kernel Maximum likelihood detection Pixel

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Feasibility of PKC in resource-constrained wireless sensor networks

Feasibility of PKC in resource-constrained wireless sensor n...

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international conference on Computer and Information Technology (ICCIT)

作者： Al-Sakib Khan Pathan Choong Seon Hong Department of Computer Engineering Kyung Hee University South Korea

In this paper we present a detailed review of the works on public key cryptography (PKC) in wireless sensor networks (WSNs). In the early days of sensor networks, public key cryptography was thought to be completely unfeasible considering its computational complexity and energy requirements. By this time, several works have proved that the lightweight versions of many well-known public key algorithms can be utilized in WSN environment. With the expense of a little energy, public key based schemes could in fact be the best choice for ensuring data security in high-security demanding WSN applications. Here, we talk about the notion of public key cryptography in WSN, its applicability, challenges in its implementation, and present a detailed study of the significant works on PKC in WSN.

关键词： Wireless sensor networks Public key cryptography Public key Hardware Data security IP networks distributed computing Computational complexity Writing Paper technology

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A new adaptive routing approach based on Ant Colony Optimization (ACO) for Ad hoc Wireless Networks

A new adaptive routing approach based on Ant Colony Optimiza...

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international conference on Computer and Information Technology (ICCIT)

作者： Niaz Morshed Chowdhury Syed Murtoza Baker Ershadul H. Choudhury Trinity College University of Dublin Ireland East West University Bangladesh

the goal of this work is to design a new adaptive routing technique for ad hoc wireless networks. this paper proposed the basic deign of the algorithm that works based on the principle of ant colony optimization (ACO). this is a probabilistic adaptive technique that changes its routes with the change of network topology over the period of time by learning its environment. It identifies appropriate paths with the feedback of previously travelled packets and maintains routing table accordingly. A self-made simulator implemented on C++ is used to evaluate performance of this algorithm on the basis of diverse adaptive issues such as change of probability, growth of pheromone intensity, randomness of the selection and packet sending rate through different paths.

关键词： Ant colony optimization Wireless networks Routing protocols Adaptive systems Mobile ad hoc networks Bandwidth Multicast algorithms IP networks distributed computing Educational institutions

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