A DSM protocol ensures that a thread can access data allocated on another machine using some consistency protocol. The consistency protocol can either replicate the data and unify replica changes periodically or the t...
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ISBN:
(纸本)9780889867741
A DSM protocol ensures that a thread can access data allocated on another machine using some consistency protocol. The consistency protocol can either replicate the data and unify replica changes periodically or the thread, upon remote access, can migrate to the machine that hosts the data and access the data there. There is a performance tradeoff between these extremes. Data replication suffers from a high memory overhead as every replicated object or page consumes memory on each machine. On the other hand, it is as bad to migrate threads upon each remote access since repeated accesses to the same distributed data set will cause repeated network communication whereas replication will incur this only once (at the cost of increased administration overhead to manage the replicas). We propose a hybrid protocol that uses selective replication with thread migration as its default. Even in the presence of extreme memory pressure and thread-migrations, our protocol reaches or exceeds the performance that can be achieved by means of manual replication and explicit changes of the application's code.
As memory transactions have been proposed as a language-level replacement for locks, there is growing need for well-defined semantics. In contrast to database transactions, transaction memory (TM) semantics are compli...
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ISBN:
(纸本)9781595939739
As memory transactions have been proposed as a language-level replacement for locks, there is growing need for well-defined semantics. In contrast to database transactions, transaction memory (TM) semantics are complicated by the fact that programs may access the same memory locations both inside and outside transactions. Strongly atomic semantics, where non-transactional accesses are treated as implicit single-operation transactions, remain difficult to provide without specialized hardware support or significant performance overhead. As an alternative, many in the community have informally proposed that a single global lock semantics [18, 10], where transaction semantics are mapped to those of regions protected by a single global lock, provide an intuitive and efficiently implementable model for programmers. In this paper, we explore the implementation and performance implications of single global lock semantics in a weakly atomic STM from the perspective of Java, and we discuss why even recent STM implementations fall short of these semantics. We describe a new weakly atomic Java STM implementation that provides single global lock semantics while permitting concurrent execution, but we show that this comes at a significant performance cost. We also propose and implement various alternative semantics that loosen single lock requirements while still providing strong guarantees. We compare our new implementations to previous ones, including a strongly atomic STM. [24] Copyright 2008 ACM.
The present study describes the results regarding the preliminary validation of a system for rehabilitation of balance control that integrates the most recent technology advances with the latest findings about motor c...
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ISBN:
(纸本)9789639799158
The present study describes the results regarding the preliminary validation of a system for rehabilitation of balance control that integrates the most recent technology advances with the latest findings about motor control and rehabilitation-engineering. The biofeedback system is based on a palmtop computer and a body sensor network, with a modular architecture, both hardware and software. Validation was performed on young healthy subjects, simulating impairment to the balance control system at the proprioception level. Promising results were obtained by means of the biofeedback system, both in terms of adequacy and usability of the system, and in terms of improvement of the balance performance.
The notion of the mobile agent has been around for over a decade in order to capture the new form of computation in communication networks. A mobile agent is a computing entity which can move around different hosts on...
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Various 3-D face synthesis techniques have been proposed and extensively used in many applications. Compared with others, single view-based face synthesis technology allows unsupervised 3-D face reconstruction without...
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Various 3-D face synthesis techniques have been proposed and extensively used in many applications. Compared with others, single view-based face synthesis technology allows unsupervised 3-D face reconstruction without any offline operations. Although many algorithms have been published, automatic and robust single view-based 3-D face synthesis still remains unsolved. In contrast to other methods, the single view-based 3-D face synthesis algorithm conducted in this paper enables automated 3-D face synthesis from an arbitrary head-and-shoulder image with the complex background. The developed system first detects the face using Bayesian skin-tone classification based on only the chrominance component, Cr. Based on the detected face, a few salient facial features, such as the corners of the eyebrows and contours of the eyes, mouth, and chin are in turn extracted using variant algorithms, including a dynamic chin extraction mechanism that will be detailed in this paper. Then, face model adaptation consisting of both global and local adaptations is imposed, according to geometric information provided by the extracted facial features. Finally, the 3-D specific face is synthesized using the adapted 3-D face model with a texture map directly derived from the input face image, followed by the implementation of facial animation using this synthesized face. [ABSTRACT FROM AUTHOR]
The paper presents the on-going EC-funded Tempus project "MSc and PhD studies in Aerospace Critical Computing" executed by the National Aerospace University, Kharkiv, Ukraine with the support of Newcastle Un...
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ISBN:
(纸本)9781605580760
The paper presents the on-going EC-funded Tempus project "MSc and PhD studies in Aerospace Critical Computing" executed by the National Aerospace University, Kharkiv, Ukraine with the support of Newcastle University and City University of London, UK and Åbo Akademi University, Turku, Finland. The state-of-the-art, completed work as well as the next steps of the development of master and doctoral courses for the specialty in critical software engineering, computersystems and networks are described. The inputs from each of the European consortium members are presented. Copyright 2008 ACM.
Privacy is becoming an increasingly important issue in many data mining applications. The miner can be untrustable party. Perturbation has been a primary tool to hide sensitive private information during data mining t...
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ISBN:
(纸本)9781605606170
Privacy is becoming an increasingly important issue in many data mining applications. The miner can be untrustable party. Perturbation has been a primary tool to hide sensitive private information during data mining task and it is used to mask the data for preserving the privacy of sensitive data. This methodology attempts to hide it by randomly modifying the data values often using additive noise. This paper proposes and presents a simple way to keep the privacy of certain individual attribute by adding noise, reconstruct the noisy data then perform the mining task to generate aggregate data and develop accurate models without access to the sensitive information of this individual attribute.
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