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研究延迟网络中的拥塞避免控制方法.在延迟网络中,随机分配网络资源,造成延迟网络资源的局限性较强,容易造成延迟网络拥塞.传统的拥塞避免控制方法是根据网络链路的反馈回执进行拥塞控制的,但是由于延迟网络的链路均匀性较差,无法建立准确的拥塞反馈回执,造成拥塞避免控制的效果较差.为了避免上述缺陷,提出了一种加权排队控制算法的延迟网络拥塞避免控制模型.对延迟网络参数进行训练,计算延迟网络的带宽,从而为延迟网络的拥塞避免控制提供准确的数据基础.建立加权排队控制模型,能够实现延迟网络的拥塞避免控制.实验结果表明,利用改进算法进行延迟拥塞避免控制,能够有效提高延迟网络的数据传递效率. 相似文献
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DTN(delay-tolerant network,延迟容忍网络)的网络特点及其采用的托管传输机制易造成网络受限资源(如缓存、带宽等)的耗尽,形成网络拥塞,导致网络性能的下降。传统TCP拥塞控制机制不适用于DTN网络。提出了一个全新的适用于DTN网络的拥塞避免与拥塞解除方案。拥塞避免根据在足够小的时间段内DTN链路的传输延迟和传输能力的确定性,建立DTN网络有向多径图,对数据发送速率、接收速率、带宽使用等链路负载分割与约束控制,尽可能地提高网络资源的利用率。拥塞解除在节点存储资源划分的基础上,通过节点内存储资源转换与节点间报文转移相结合的方法,解除DTN网络的拥塞状况。仿真结果显示,与其他DTN拥塞控制机制相比,所提方案具有良好的报文交付率、网络开销等网络性能。 相似文献
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研究网络拥塞优化控制问题.由于网络承载量猛增,产生堵塞,延迟增加,使网络效率降低.传统网络的TCP拥塞控制算法不能区分网络拥塞和网络随机错误丢包,导致网络带宽利用率低,网络拥塞严重,甚至导致网络崩溃.为了降低网络拥塞的概率,提出了一种改进的TCP拥塞控制算法.改进的网络拥塞控制算法首先通过对网络状态进行预测,能够有效区分网络拥塞和网络随机错误丢包,同时对TCP网络拥塞控制算法的拥塞避免、快速重传和快速恢复机制进行改进,改善网络性能.最后采用NS2仿真器对算法进行仿真,实验结果表明,提高了网络平均吞吐量,带宽利用率更高,很好的避免了网络拥塞. 相似文献
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视频实时传输中的速率控制研究 总被引:4,自引:0,他引:4
视频在互联网上的实时传输常因其要求高带宽、低延迟而造成网络拥塞。传统TCP基于窗口的拥塞控制已经不适用于实时传输中的拥塞控制,该文讨论了基于速率的网络拥塞控制方法,它采用自适应码率和分层的视频编码技术,详细说明了基于源端和收端的各种速率控制方法。 相似文献
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在高带宽时延乘积网络中,现有TCP协议由于其使用的拥塞控制机制使得数据流长时间以低速率发送数据,不能有效利用网络带宽,造成带宽利用率随着带宽的增大而下降。对高带宽时延乘积网络中TCP的性能进行仿真,结果表明在该网络环境中使用TCP传输数据不能有效利用网络带宽。最后详细分析拥塞控制机制造成TCP使用带宽利用率低的原因。 相似文献
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EHSTCP:改进的高速TCP算法 总被引:2,自引:0,他引:2
TCP在高带宽时延积网络中不能获得良好的性能,主要表现为低的吞吐量和大的窗口震荡.HSTCP算法解决了传统TCP算法在高带宽时延积网络下的性能瓶颈,但HSTCP在拥塞点时会产生大量的数据包丢失,同时当队列管理为去尾算法时,存在着严重的RTT不公平性问题.针对HSTCP算法的性能缺陷,该文提出一种在拥塞避免阶段进行拥塞避免模式切换的改进算法,称为EHSTCP.基于拥塞窗口历史值的端到端可用带宽预测方法,利用拥塞窗口历史信息来判断拥塞避免切换点.同时引入RTT公平因子,消除了HSTCP的RTT不公平性问题.NS2仿真实验验证了算法的有效性. 相似文献
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S. Shaw 《Journal of Computer Assisted Learning》1993,9(2):93-99
Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained. 相似文献
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European Community policy and the market 总被引:1,自引:0,他引:1
C. Lloyd 《Journal of Computer Assisted Learning》1993,9(2):86-91
Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven. 相似文献
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融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。 相似文献
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张涛 《计算机测量与控制》2015,23(1):86-89
为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值. 相似文献
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Wayne O’Brien Author Vitae 《Journal of Systems and Software》2008,81(11):1997-2013
Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them. 相似文献
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This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives. 相似文献
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潘丽 《自动化与仪器仪表》2014,(7):80-82
自然界的绝大部分信号都是以模拟的形式存在,因此模拟信号的采集转换存储在数字时代十分关键。文章讨论了在雷达信号处理领域基于AD9626的AD采集存储卡的设计原理、硬件结构和程序设计与芯片配置等问题,为今后相关领域的研究提供了可参考的方案。 相似文献
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Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what
is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic
sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and
its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of
an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify
robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can
or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
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Jacob Palme 《Software》1979,9(9):741-747
The COM teleconferencing system was designed to be easy to use for both beginners and people with much computer experience. A number of design choices in organizing the human-computer interface were considered very carefully. These design problems are not unique for teleconferencing applications, but will appear in many other developments of human-computer interfaces for non-computer specialists. This report discusses naming conventions, menu format, user commands, help facility and the treatment of ‘type ahead’ from the users. 相似文献