高速雷达数据采集系统的FPGA设计

高速雷达数据采集系统的设计方法。该系统由FPGA芯片完成各芯片之间的逻辑控制,具有设计灵活、结构简单、实时性高、可靠性高等优点。     

校园网流量抽样测量系统设计与实现

随着高速网络技术的发展,大多数高校引入了千兆网,校园网络日益规模化和复杂化,使得实时在线的流量测量变得比较困难,基于抽样的流量测量方法作为一种可扩展的测量技术已成为人们经常采用的一种有效的流量测量技术。本文采用"弱化的贪心算法"确定各网段的最佳测点,并采用IP掩码匹配的分布式抽样测量技术将各测量点同步采集的流量经抽样后存储到服务器的不同储存区域,然后根据测量目标对各网段采集的流量进行汇聚、分析和统计。从节约成本出发,本文引入了双机协作抽样技术进行测量,此双测量主机系统充当了服务器、测量器和分析器角色,整个测量无需专用测量器和服务器,可以基本取代市场专用的流控测量设备,能实现对整个校园网流量的掌控。     

基于GPRS的明渠流速流量检测系统研究

根据明渠流速流量测量技术规范和远距离数据传输的需求,以旋浆式流速仪为一次测量仪器,设计了基于GPRS的明渠流速流量检测系统。系统采用固态存储技术,实现数据在下位机中的大量存储。通过采集电路及GPRS终端,利用通用分组无线业务(GPRS)和Internet网实现远程数据的采集与控制,解决了水文水生态监测中分散数据传输问题,实现了水文信息实时采集传输和处理的无线化、网络化、智能化。     

高速网络流量特性与流数据库设计

长期的流量测量数据非常珍贵,因为通过对这些长期的流量数据进行分析,不但能发现Internet和运行于其上的各种网络应用如何在演变,更重要的是还可发现其中不变的规律。提出了网络监测平台的流量数据多级存储系统设计,并根据高速网络流量的重尾分布特性,采用合理的流数据存储策略,可大幅度减少要存储的数据量,同时又保留了必要的网络信息,适应于不同精度的测量需求并兼顾了成本、性能和效率。     

CCD在人眼屈光度测量中眼底图像高速采集的研究

论述了人眼屈光度的测量原理，通过使用CCD对眼底图像的采集，设计了一套DMA方式的高速采集系统。该系统性能可靠、实用性强。     

Effect of sidewall boundary conditions on unsteady high speed cavity flow and acoustics

The effect of sidewall boundary conditions on the computed unsteady flow and sound pressure level is investigated in a transonic open cavity. The hybrid approach used for modeling turbulence combines a Reynolds averaged mode in the boundary layer, and a large eddy simulation mode in the massively separated flow region within the cavity to resolve the wide dynamic range involved. Computational results are presented for the instantaneous vorticity and for the sound pressure level spectra. Comparison of the results obtained using inviscid and periodic sidewall boundary conditions show the sensitivity of the computed SPL spectra and autocorrelation to the conditions enforced at the sidewalls. The computed SPL spectra are also compared with available experimental results, with LES computational results, and with prior investigations based on the same hybrid turbulence model without the wall function used in the current investigation. The comparisons show that the current results obtained using inviscid sidewall boundary conditions are closest to the experimental sound pressure level spectra and that agreement is achieved at considerable saving in required computational resources.     

Double speed single production line

This paper presents a hybrid push and pull production management approach called double speed single production line (DSSPL), developed for industries that produce a large variety of slightly different items subject to highly variable demand. Because of this framework, only mediocre lead times for all their products can be guaranteed. The DSSPL system suggests improving their logistic performances by splitting products into A- and B-classes, according to a market oriented policy, then by producing, on a single line, but at different speeds, the A- (fast) and the B-products (slow), thus leading to a better allocation of production resources. A discrete event simulator has been developed in order to evaluate performances of the DSSPL approach to pure push and pull systems. First results are presented and the performance of the DSSPL system is discussed.     

网络自适应公平分组抽样算法研究

针对SGS(sketch guided sampling)的缺陷,提出了一种网络自适应公平抽样算法.根据抽样分组估计出值流量大小,并依据该值调整抽样比,使之适应于流量变化,从而达到对各种流的公平抽样的效果.对算法的相关性质进行了证明与分析,基于实际互联网数据进行了实验比较,实验结果表明,该算法具有准确性、自适应性、易于工程实现等优点.     

高速采样下含网络攻击的信息物理系统$H_/H_infty$故障检测

研究高速采样情况下,含有网络攻击的信息物理系统多目标故障检测问题.考虑系统同时存在时变时延、执行器网络攻击和传感器网络攻击,基于Delta算子对上述系统进行离散化处理,建立在高速采样的条件下,故障与攻击并存的离散时间模型.构造H＿/H_∞故障检测滤波器,使系统具有对随机扰动的鲁棒性,且具有对检测信号的高灵敏性.采用Lyapunov-Krasovskii泛函和线性矩阵不等式的方法,提出系统具有渐近稳定性以及H＿/H_∞性能的充分条件.仿真结果验证了所提方法的可行性和有效性.     

Cantilever probes for high speed AFM

Since the invention in 1986 atomic force microscopy (AFM) has become the most widely used scanning probe microscopy (Binnig et al. in Phys Rev Lett 56:930–933, 1986). The microscope images the interaction of forces like Van der Waals or Coulomb forces between a sample and the apex of a small tip integrated near the free end of a flexible cantilever. But as all other scanning probe techniques the AFM requires serial data acquisition and suffers therefore from a low temporal resolution. Enhancing the speed to video rate imaging makes high demands on scanner technology, control electronics and on the key feature the cantilever with integrated sharp stylus. For the cantilever probes, fundamental resonance frequencies in the MHz regime are envisaged while the force constant of a few nN/nm shall be maintained. We present different novel AFM probes with ultrashort cantilevers and integrated sharp tips for high speed AFM while focusing on widely dispersed applications and on aspects of mass fabrication.     

DANTE's plans for high speed services

DANTE has been formed as a non-profit company by a group of national research networks in order to provide them with international services. In addition to the 2◊Mbps multi-protocol service which it already operates, DANTE is making plans to introduce 34 Mbps and higher speed services as soon as this is feasible. Much of the planning activity is being carried out in the contect of the Eureka EuroCAIRN Project. The scope of the activity and the issues that need to be addressed are described.     

高速风洞微型测量系统研制及应用

研制了一种高速风洞微型测量系统,由电气接口模块、增益控制模块、低通滤波模块、扫描采集模块、主控模块、LAN总线接口模块组成,实现了电压信号放大、低通滤波、模数转换、数据处理与分析等功能,静态校准结果表明关键性能指标与风洞常规测量系统相当,满足风洞试验信号采集需求。将该系统成功应用于2.4米跨声速风洞标模测力试验,开展了对比试验以及测量精度试验,并与常规测量系统试验结果进行了对比,试验结果表明微型测量系统精度和稳定性满足试验要求,能够适应高速风洞应用环境。     

基于FPGA的交流电测量仪的设计

根据交流采样的原理,设计出基于FPGA开方算法,解决了实时计算电压有效值和频率的问题.充分发挥FPGA硬件并行计算的特性,实现高速运算和可靠性的结合,能够较好地解决精度与速度的问题.为稳定控制装置快速判断元件故障提供了充足时间,满足电力系统实时性、可靠性的要求.     

A passivity-based controller under low sampling for speed control of PMSM

Controller performances are strongly limited by the switching frequency of the converter and the computational capacity of the target board. Therefore, in such a context the design of controllers that provide good performances under possible large sampling period length is necessary. To tackle these limitations, a digital design is described for speed control of permanent magnet synchronous machines. It is based on the interconnection and the damping assignment passivity-based control (IDA-PBC) techniques extensions to the sampled-data context.     

Proactive congestion control for high speed networks

The next generation high speed networks which are characterized by large bandwidth propagation delay products are expected to support applications with diverse traffic characteristics and Quality of Service (QoS) requirements. Since statistical multiplexing is employed in these networks, congestion control and avoidance mechanisms are required for the delivery of QoS required by various applications.A number of reactive flow control schemes have been developed in the past for best effort applications. It has been well established that these schemes are not effective for networks with large bandwidth propagation delay products as the feedback information generated in the network can be outdated by the time it reaches the sources. In this paper, this problem (referred to as the bandwidth mismatch problem) is investigated and a proactive feedback (PF) based flow control scheme which attempts to eliminate the bandwidth mismatch problem by generating and transmitting early feedback messages is introduced. With cooperation among the network nodes and sources, the PF based flow control scheme can significantly increase the QoS delivered to the best effort applications. In addition to the increased level of delivered QoS, fair rate allocations to the best effort applications are also possible since the efficiency of the scheme becomes independent of the length of the propagation delays, once the bandwidth mismatch is eliminated.     

高速数字电路的串音现象研究

在数字信号的高速传输中,信号完整性的问题已越来越受到硬件工程师的高度关注。串音现象是信号完整性的问题之一,随着印刷电路板的布线密度增加,尤其是长距离并行线的布局,更容易发生串音现象。从上升沿时间、跨分割平面、传输模式、中间保护线是否接地四个方面阐述了影响串音的因素,并提出了相应的解决方法。     

Adaptive transport service for high speed networks

It has been shown that protocol processing represents a severe bottle-neck for high speed computer networks. The disadvantages of currently proposed solutions are their incompatibility with existing standardised protocol implementations, their complexity and/or their inflexibility. One method of alleviating these limitation is to have an adaptable protocol stack, as proposed in the paper. Preliminary results are presented which show that significant gains in throughput can be achieved while creating a framework suitable for future applications.     

Buffering for sustained,high speed transfers

It is shown that a circular buffering system is more effective than conventional double or treble buffering for handling sustained, high speed data transfers from say analog-to-digital converters to disk storage devices.