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951.
基于RTX的复杂虚拟试验分层实时网络环境研究 总被引:1,自引:1,他引:0
复杂实时仿真系统中不同层次对实时性、可靠性要求各不相同;网络和操作系统是该类系统环境的重要组成部分;针对硬件在回路试验的实时需求,提出了基于RTX下的反射内存网的半实物接入网络,构建了基于RT-TCP/IP的虚拟试验局域网;其操作系统层面,设计为弱实时任务在Windows内核上运行,而强实时任务分布在RTX内核之上;文中对各层面的实时性进行了测试,分析了层面间的实时性约束;结合某飞行试验系统的虚拟试验,给出了具体的设计方案,满足了应用中不同实时性的要求。 相似文献
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Hong Fan Qingfeng Meng Youyun Zhang Qiang Gao Fengni Wang 《Digital Signal Processing》2009,19(4):583-595
Matching pursuit (MP) extracts signal feature components by decomposing the observed signal into a linear expansion of waveforms that are selected from a redundant dictionary of basis functions. It is difficult to predefine a parametric basis function that contains all prior information about the observed signal in practice, which restricted the application of MP. Focusing on this defect of MP, we present a modified algorithm of MP which decomposes the observed signal into a series combinations of waveforms, these waveforms are calculated by the nonparametric waveform estimation (NWE) method and used to best match the signal local structures. As a result, it is not needed to predefine the parametric basis function. With the NWE method, the adaptive adjustment of template signals makes it unnecessary for the method to require priori information, so that in practical applications it has better flexibility and adaptability. The extraction results of simulation signals are compared with the traditional MP decomposition, thus verifying the function of the proposed method. The extraction of testing signals on the rotor rig has again verified the feasibility and effectiveness of the method. 相似文献
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In this article, the adaptive integral method (AIM) is used to analyze large‐scale planar structures. Discretization of the corresponding integral equations by method of moment (MoM) with Rao‐Wilton‐Glisson (RWG) basis functions can model arbitrarily shaped planar structures, but usually leads to a fully populated matrix. AIM could map these basis functions onto a rectangular grid, where the Toeplitz property of the Green's function would be utilized, which enables the calculation of the matrix‐vector multiplication by use of the fast Fourier transform (FFT) technique. It reduces the memory requirement from O(N2) to O(N) and the operation complexity from O(N2) to O(N log N), where N is the number of unknowns. The resultant equations are then solved by the loose generalized minimal residual method (LGMRES) to accelerate iteration, which converges much faster than the conventional conjugate gradient method (CG). Furthermore, several preconditioning techniques are employed to enhance the computational efficiency of the LGMRES. Some typical microstrip circuits and microstrip antenna array are analyzed and numerical results show that the preconditioned LGMRES can converge much faster than conventional LGMRES. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. 相似文献
955.
Broadcasting scheme with low client buffers and bandwidths for video-on-demand applications 总被引:1,自引:1,他引:0
Hsiang-Fu Yu Hung-Chang Yang Yao-Tien Wang Ping-Lin Fan Chu-Yi Chien 《Multimedia Tools and Applications》2009,42(3):295-316
Efficient data broadcasting is independent of request arrivals, and is thus highly promising when transmitting popular videos.
A conventionally adopted broadcasting method is periodic broadcasting, which divides a popular video into segments, which
are then simultaneously broadcast on different data channels. Once clients want to watch the video, they download the segments
from these channels. The skyscraper broadcasting (SkB) scheme supports clients with small bandwidths. An SkB client requires
only two-channel bandwidths to receive video segments. This work proposes a reverse SkB (RSkB) scheme, which extends SkB by
reducing buffering spaces. The RSkB is mathematically shown to achieve on-time video delivery and two-channel client bandwidths.
A formula for determining the maximum number of segments buffered by an RSkB client is presented. Finally, an analysis of
RSkB reveals that its client buffer requirements are usually 25–37% lower than SkB. Extensive simulations of RSkB further
demonstrate that RSkB yields lower client buffer demand than other proposed systems.
相似文献
Hsiang-Fu YuEmail: |
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IPSec VPN数据安全传输 总被引:2,自引:1,他引:1
随着互联网技术的普及,VPN技术得到了广泛的应用。VPN是采用加密等技术,将数据加密后在Internet等公共网络上传输,其效果相当于在公共网络上建立一条专用的、私有的、虚拟通道,由此创建一条安全、可靠的连接。本文从互联网通讯所面临的安全风险开始,先简要地介绍了几种常见的VPN解决方案,然后再详细地介绍了IPSec VPN的技术体系与工作模式。 相似文献
959.
针对可拓诊断模型在实际应用中存在诊断准确度不高的问题,提出了一种基于主元分析的可拓故障诊断模型;该模型借助主元分析方法获取属性互不相关的训练集,在此基础上建立诊断对象描述的物元模型,然后利用关联函数定量计算待测对象对于每一种故障模式的关联程度,进而判断可能的故障模式;用该模型对某电喷发动机的运行状态进行了识别,实验结果表明,基于主元分析的可拓诊断模型可以大幅度提高诊断结果的准确率,具有重要的实践意义。 相似文献
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