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International Conference on Dependable systems and networks (DSN)

作者： Yinglung Liang Yanyong Zhang A. Sivasubramaniam M. Jette R. Sahoo Electrical & Computer Engineering Department Rutgers University USA Computational Resource Management Group Lawrence Livemore National Laboratory USA Computer Science & Engineering Department Pennslyvania State University USA Exploratory Systems Software Department IBM Thomas J. Watson Research Center USA

The growing computational and storage needs of several scientific applications mandate the deployment of extreme-scale parallel machines, such as IBM's BlueGene/L which can accommodate as many as 128 K processors. One of the challenges when designing and deploying these systems in a production setting is the need to take failure occurrences, whether it be in the hardware or in the software, into account. Earlier work has shown that conventional runtime fault-tolerant techniques such as periodic checkpointing are not effective to the emerging systems. Instead, the ability to predict failure occurrences can help develop more effective checkpointing strategies. Failure prediction has long been regarded as a challenging research problem, mainly due to the lack of realistic failure data from actual production systems. In this study, we have collected RAS event logs from BlueGene/L over a period of more than 100 days. We have investigated the characteristics of fatal failure events, as well as the correlation between fatal events and non-fatal events. Based on the observations, we have developed three simple yet effective failure prediction methods, which can predict around 80% of the memory and network failures, and 47% of the application I/O failures

关键词： Failure analysis Predictive models Production systems Checkpointing Concurrent computing Parallel machines Hardware Runtime Fault tolerant systems Prediction methods

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Topology Maintenance of Wireless Sensor networks in Node Failure-prone Environments

Topology Maintenance of Wireless Sensor Networks in Node Fai...

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IEEE International Conference on Networking, Sensing and Control

作者： L. Frye Liang Cheng Shenfu Du M.W. Bigrigg Department of Computer Science Kutztown University Kutztown PA USA Laboratory of Networking Group (LONGLAB) Department of Computer Science and Engineering Lehigh University Bethlehem PA USA Visiting Research Scholar in LONGLaboratory Lehigh University USA Institute for Complex Engineered Systems Carnegie Mellon University Pittsburgh PA USA

A critical issue in wireless sensor networks is topology management, and maintaining connectivity throughout the network and having a sufficient network lifetime in particular. There have been many topology management schemes proposed. Most of them conserve energy by periodically putting nodes to sleep. One consideration often overlooked is the fact that sensor nodes fail, especially in harsh environments. In this paper, a modification to an existing topology management scheme, Naps, is proposed to ensure very minimal data loss while also handling node failures. The idea is to conserve energy to prolong the lifetime of the nodes and the sensor network while maintaining a constantly connected sensor network. Simulation results demonstrate that failed nodes do not have a significant impact on network connectivity or lifetime, at least in a random, uniform deployment. The paper also illustrates that two different approaches taken in the Naps modification for compensating for failed nodes produce similar results

关键词： Network topology Wireless sensor networks Intelligent networks Sleep Condition monitoring Relays Batteries Terrorism Military communication Degradation

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Acoustic source localization in sensor networks with low communication bandwidth

Acoustic source localization in sensor networks with low com...

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Workshop on Intelligent Solutions in Embedded systems

作者： Gyula Simon Laszlo Sujbert Embedded Information Technology Research Group Hungarian Academy of Sciences (ATOMKI) Budapest Hungary Department of Computer Science Pannon University Veszprem Hungary Department of Measurement and Information Systems Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

A new acoustic localization scheme is proposed, which can be applied in sensor networks with low communication bandwidth. The first step of the two-stage algorithm is distributed and is evaluated at the sensors having possibly low communication capabilities. The sensors detect various events in the acoustic signal and transmit only the event descriptors to the base station where the sensor fusion is calculated in the second step using a novel generalized consistency function. Test results validate the performance of the proposed system in a noisy and reverberant environment. According to experiments, the proposed system decreases the necessary communication bandwidth with multiple orders of magnitude and still provides high accuracy comparable with that of the sophisticated beam-forming methods

关键词： Acoustic sensors Bandwidth Sensor fusion Sensor phenomena and characterization Acoustic signal detection Event detection Base stations Acoustic testing System testing Acoustic noise

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A context-aware trust-based security system for ad hoc networks

A context-aware trust-based security system for ad hoc netwo...

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Workshop of the 1st International Conference on Security and Privacy for Emerging Areas in Communication networks, 2005

作者： Moloney, Maria Weber, Stefan Distributed Systems Group Department of Computer Science Trinity College Dublin 2 Ireland

ISBN: (纸本)0780394690

Mobile ad-hoc networks (MANETs) comprise computer nodes which communicate over wireless links without any central control. Therefore, they must be able to make fully autonomous security decisions. This introduces new security challenges that existing security models and mechanisms do not adequately address [3]. In this paper we present a trust-based security system that deals with the specific challenges of MANETs by combining decentralised security management and context-aware computing. With this combination, our trust-based security system can establish appropriate trust levels for every situation. © 2005 IEEE.

关键词： computer networks

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Effects of routing computations in content-based routing networks with mobile data sources 05

Effects of routing computations in content-based routing net...

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MobiCom 2005: Eleventh Annual International Conference on Mobile Computing and Networking

作者： Muthusamy, Vinod Petrovic, Milenko Jacobsen, Hans-Arno Middleware Systems Research Group Department of Electrical and Computer Engineering University of Toronto Middleware Systems Research Group Department of Computer Science University of Toronto

ISBN: (纸本)9781595930200

This paper presents the first quantitative evaluation of the role of routing computations on performance when mobility is introduced to a content-based routing network. Additionally, the paper identifies the factors that affect the performance of a distributed publish/subscribe architecture supporting mobile publishers, formalizes publisher mobility protocols for distributed publish/subscribe systems, and develops and evaluates protocols that reduce the costs associated with supporting mobile publishers in publish/subscribe systems. Our results show that ignoring route computation time paints a false picture of the scalability of content-based routing networks, but that with appropriate protocols the adverse effects can be mitigated. Copyright 2005 ACM.

关键词： Computation theory

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Small-scale peer-to-peer publish/subscribe

Small-scale peer-to-peer publish/subscribe

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2nd Workshop on Peer-to-Peer Knowledge Management, P2PKM 2005 - Colocated with the 2nd Annual International Conference on Mobile and Ubiquitous systems: Neworking and Services, MobiQuitous 2005

作者： Muthusamy, Vinod Jacobsen, Hans-Arno Middleware Systems Research Group Department of Electrical and Computer Engineering University of Toronto Canada Middleware Systems Research Group Department of Computer Science University of Toronto Canada

The scalability of publish/subscribe (pub/sub) systems and distributed hash tables (DHTs) have been extensively studied in the literature. However, less well-known are properties of the pub/sub model and DHTs that make them suitable for small networks. This paper articulates these benefits, and evaluates the performance of a DHT-based pub/sub implementation in small-scale networks. We find that a fundamental assumption of DHT-based data management applications is violated in small networks, and this makes the pub/sub implementation exhibit poor load balance under certain workloads. This work illustrates that data management applications that scale in large networks may not scale in small networks.

关键词： Information management

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Providing Hard Real-Time Guarantees in Context-Aware Applications: Challenges and Requirements

Providing Hard Real-Time Guarantees in Context-Aware Applica...

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IEEE International Symposium on Network Computing and Applications

作者： M. Boulkenafed B. Hughes R. Meier G. Biegel V. Cahill Department of Computer Science Distributed Systems Group Dublin Ireland

Context-aware applications rely on the ability to perceive the state of the surrounding environment. In this paper, we address a class of such applications where real-time guarantees are required on top of mobile ad hoc networks. While guaranteed timeliness is a critical requirement, the unpredictability of dynamic wireless networks adversely impacts such guarantees. Therefore, we identify the challenges and the requirements on different architectural levels in order to provide timeliness guarantees. None of the existing systems have succeeded in providing adequate solutions to all of the identified requirements. Therefore, we describe a cross-layer architecture that supports the development of real-time context-aware applications for wireless networks, in particular, ad hoc networks. This cross-layer architecture is based on three main components. (i) Sentient objects - mobile intelligent software agents that extract, interpret and use context information. (ii) Event-based real-time middleware supports communication between sentient objects and provides hard real-time guarantees within adaptable geographic spaces. (iii) A real-time routing and resource reservation protocol attempts to discover and maintain real-time constrained routes within these proximities in a multi-hop ad hoc network

关键词： Wireless networks computer architecture Context Ad hoc networks Mobile ad hoc networks Application software Intelligent agent Intelligent networks Software agents Data mining

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Event handling for the universal enterprise

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Information Technology and Management 2005年第1期6卷 123-148页

作者： Cilia, Mariano Bornhövd, Christof Buchmann, Alejandro P. Databases/Distributed Systems Group Department of Computer Science Darmstadt University of Technology 64289 Darmstadt Hochschulstr. 10 Germany Faculty of Sciences UNICEN Tandil Argentina IBM Almaden Research Center San Jose CA United States

Current trends in the global economy are leading to inter-enterprise interactions and to new business models that depend on the timely notification of events and the reaction to them. In this paper we present a distributed reactive middleware that supports the proactive notification of events in heterogeneous environments. The infrastructure consists of a publish/subscribe notification mechanism and a reactive functionality. We represent events that may originate from heterogeneous sources together with their ontology-based context metadata to make them self-describing beyond the boundaries of the event source. We introduce the notion of concept-based addressing to publish/subscribe systems. Concept-based addressing allows us to express subscriptions to events according to different contexts than those of the published events and yet match them successfully. By using ontologies and context definitions consistently for events, notifications, subscriptions and reactions we provide the necessary support for event handling in global enterprises. © 2005 Springer science + Business Media, Inc.

关键词： Business rules Event handling Event-based applications Publish/subscribe Reactive service Semantic data integration

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Power Management for Stationary Machines in a Pervasive Computing Environment

Power Management for Stationary Machines in a Pervasive Comp...

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Annual Hawaii International Conference on System sciences (HICSS)

作者： C. Harris V. Cahill Distributed Systems Group Department of Computer Science Trinity College Dublin Ireland

This paper examines effective power management of users' stationary desktop PCs in a pervasive computing office environment. The objective being to minimise the building's electricity consumption while maintaining acceptable desktop PC performance. Current state of the art power management is focused on developing polices for mobile devices, which are ineffective for stationary machines. Effective stationary policies need to obtain context from the user of the machine, but there is a balance between what detail of context is necessary and how much this extra context costs both monetarily and energy wise. We have implemented two location aware policies which detect presence of the user's Bluetooth enabled mobile phone. Trial results indicate that with these policies it is possible to get within 8% of optimal energy consumption with little performance degrade. However, this is the best case and the results are dependent on the user's usage patterns and the geographical layout of the office.

关键词： Energy management Environmental management Pervasive computing Energy consumption Power system management Personal communication networks Costs Bluetooth Mobile handsets Degradation

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Exploiting user behaviour for context-aware power management

Exploiting user behaviour for context-aware power management

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IEEE International Conference on Wireless and Mobile Computing, Networking And Communications (WiMob)

作者： C. Harris V. Cahill Distributed Systems Group Department of Computer Science Trinity College Dublin Ireland

With more and more computing devices being deployed in buildings there has been a steady rise in buildings' electricity consumption. At the same time there is a pressing need to reduce overall building energy consumption. Pervasive computing could further exacerbate this problem but it could also provide a solution. Context information (e.g., user location) likely to be available in pervasive computing environments could enable highly effective device power management. The objective of such context-aware power management (CAPM) is to minimise the overall electricity consumption of a building while maintaining acceptable user-perceived device performance. To investigate the potential of CAPM we conducted experimental trials for two simple location-aware power management policies. Our results highlight the presence of two distinct user behaviour patterns but also show that location alone is not enough for effective power management. We therefore propose a CAPM framework that employs Bayesian networks to support prediction of user behaviour patterns from multi-modal sensor data for effective power management. We further propose the use of acoustic data as an interesting context for predicting finer-grained user behaviour. The paper presents an initial evaluation of the resulting framework.

关键词： Energy management Energy consumption Pervasive computing Power system management computer network management Costs Pressing Bayesian methods Hard disks Battery management systems

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