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排序方式: 共有888条查询结果,搜索用时 46 毫秒
31.
Wireless sensor networks (WSNs) are a kind of communication networks having independent sensor nodes that form multi-hop ad hoc network to transfer data. In the past few years, various transport control protocols in wireless sensor networks (WSNs) have been developed and proposed in the literature. In this paper, we have analyzed pump slowly, fetch quickly (PSFQ) protocol and presented an improved transport layer protocol for wireless sensor networks. The improved protocol has been analyzed based on various factors such as average latency and average error tolerance and it is found that the proposed protocol is better than PSFQ in terms of these factors. 相似文献
32.
1.引言如何分析、评价并行程序的性能是并行计算的一个重要研究问题。RAM模型为串行算法分析提供了理论基础。据此,我们可以用big-O模型来分析其算法的复杂性。但是,在并行环境下,由于处理机之间增加了通信,使得并行程序及算法分析问题更加复杂。如何在并行程序和计算机结构之间建立一种联系?许多人 相似文献
33.
一种描述特征交互作用的类属命名机制研究 总被引:1,自引:0,他引:1
文中描述了产成式设计中的几类特征编辑操作的结构,并设法将所有因特征发生交互作用而引起的面的拓扑变化(如融合、分割)引入一种类命名机制,它在基于特征造型系统中起到标识实体模型中的拓扑实体和检验拓扑实体存在的合法性的作用. 相似文献
34.
存储器访问延迟已经成为高性能微处理器性能发挥的关键障碍之一。预取是隐藏访存延迟的重要手段。其通常做法是显式执行指令将数据在实际使用前先和取到离微处理器附近的地方,但是这种方法增加了程序设计人员的负担。本文提出了一种硬件预取方法,即在存储控制器中设计一个VPFB机构用来隐藏访存延迟,并通过模拟分析了它的效果。 相似文献
35.
Replica Placement Strategies in Data Grid 总被引:1,自引:0,他引:1
Replication is a technique used in Data Grid environments that helps to reduce access latency and network bandwidth utilization.
Replication also increases data availability thereby enhancing system reliability. The research addresses the problem of replication
in Data Grid environment by investigating a set of highly decentralized dynamic replica placement algorithms. Replica placement
algorithms are based on heuristics that consider both network latency and user requests to select the best candidate sites
to place replicas. Due to dynamic nature of Grid, the candidate site holds replicas currently may not be the best sites to
fetch replicas in subsequent periods. Therefore, a replica maintenance algorithm is proposed to relocate replicas to different
sites if the performance metric degrades significantly. The study of our replica placement algorithms is carried out using
a model of the EU Data Grid Testbed 1 [Bell et al. Comput. Appl., 17(4), 2003] sites and their associated network geometry. We validate our replica placement
algorithms with total file transfer times, the number of local file accesses, and the number of remote file accesses. 相似文献
36.
Towards More Complete Models of TCP Latency and Throughput 总被引:2,自引:0,他引:2
Recently, several researchers have developed equations for modeling TCP behaviors, such as the expected throughput or latency, based on Markov chains derived from TCP with additional simplifying assumptions. In this paper, we suggest new directions for Markov chain analyses of TCP. Our first contribution is to closely examine not just the expectation but the entire cumulative distribution function of transfer times under various models. Particularly for short or medium transfers, the distribution is likely to be more useful than the expectation in terms of measuring end-user satisfaction. We find that the shapes of TCP cumulative distribution functions are remarkably robust to small changes in the model. Our results suggest that simplifying Markov analyses can be extended to yield approximations for the entire distribution as well as for the expectation.Our second contribution is to consider correction procedures to enhance these models. A correction procedure is a rule of thumb that allows equations from one model to be used in other situations. As an example, several analyses use a Drop-Tail loss model. We determine correction procedures for the deviation between this model and other natural loss models based on simulations. The existence of a simple correction procedure in this instance suggests that the high-level behavior of TCP is robust against changes in the loss model. 相似文献
37.
38.
为了使失效检测满足分布式网络环境的要求,针对分布式网络环境中存在的网络延迟和丢包两种情形,提出了基于失效检测点和二次检测模式的失效检测改进算法。该算法根据误判次数动态计算二次检测时间,在失效检测的准确性和效率之间作了较好的权衡。理论分析和测试结果均表明该算法能够适应网络环境的变化并有效地减小网络丢包对失效检测算法的影响。 相似文献
39.
The authors examined the effect of learning on multiple encounters with sources of social ambiguity in individuals with generalized social phobia (GSP). The authors modified G. B. Simpson and H. Kang's (1994) paradigm and presented prime-target word pairs to individuals with GSP and nonanxious controls (NACs) to prime threat and nonthreat meanings of homographs and examine the effect of this priming on later encounters with that homograph. Consistent with previous research, NACs showed faster response latencies naming a target primed by a homograph with the same meaning activated in two successive trials than naming the same target primed by an unrelated word. Furthermore, NACs showed slower response latencies naming a target when a different meaning of the homograph prime was activated in successive trials than naming a target primed by an unrelated word. GSP participants did not show this pattern in learning a nonthreat meaning of a homograph. These results support the hypothesis that a faulty learning mechanism may be involved in social anxiety. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
40.
Lischetzke Tanja; Cuccodoro Ghislaine; Gauger Anja; Todeschini Laure; Eid Michael 《Canadian Metallurgical Quarterly》2005,5(4):431
This research investigated a new method to measure momentary affective clarity indirectly, which is based on latencies of responses to state affect items. Three studies revealed that this indirect measure of momentary clarity demonstrated high reliability and stability as well as convergent and predictive validity. The indirect measure was associated with dispositional clarity when the concept of clarity was activated before measuring response latencies (Studies 1 and 2) and was related to self-reports of momentary clarity (Study 3). Furthermore, Study 3 demonstrated that indirectly measured clarity decreased after an affectively complex film. Indirectly, but not directly, measured momentary clarity predicted a more positive affective state at the end of the study. This effect was mediated by affect regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献