ADI方法求解完全跨声速非定常小扰动方程

本文修改了Whitlow的ADI格式,以便求解另一变形的完全跨声速小扰动方程。本文给出的NACA64A006和NACA0012翼型的非定常跨声速流动的计算结果与其它数值结果和实验结果的比较表明本文格式是合理的且便于实际应用的。     

高速低压差分信号（LVDS）器件应用设计方法研究

随着高速LVDS器件得到广泛应用，在高速信号使用LVDS传输时，信号传输线路问题、信号传输波形的最佳化成为非常重要的课题之一。由于印制电路板的布局布线直接影响信号传输质量，因此利用仿真对印制板分析成为设计上不可缺少的手段。有鉴于此，文章深入探讨了高速电路的设计，总结出设计技巧。     

胶州湾环境污染—卫星遥感信息分析

陆地卫星主题绘图仪(TM)图象和我国国土普查卫星全景相机照片解译分析与现场调查表明,胶州湾东岸工业废水污染相当严重,主要污染源集中在海泊河、李村河、娄山河以及沧口区沿海一线,污染水带宽达4～7km,在落潮流携带下扩散至湾口外海。由青岛碱厂排污形成的“白滩”污染区现有面积为0.53km~2。青岛市大气污染严重,源自市区的烟羽宽达14km,顺风飘逸远达30km,势必造成酸雨等灾害。     

High speed driving of a gain-switched laser diode with anexponential transmission line

With the increase of information capacity of an airborne system, high speed driving of laser diodes have been of interest. In order to match the low resistive LD, proposed in this paper is an exponential transmission line, which is used as preshaping to compensate the pattern effect in gain switching of laser diodes. It also will be used to overcome the effect of parasitic elements in high speed driving to improve the rise and trail edges of the output waveform. An accurate circuit model of the exponential line for the PSPICE program has been developed and simulations are conveniently carried out by employing PSPICE     

Flutter analysis of an airfoil with bounded random parameters in incompressible flow via Gegenbauer polynomial approximation

The effects of parameter uncertainty on the flutter characteristics of a two-dimensional airfoil in an incompressible flow were investigated through Gegenbauer polynomial approximation. The uncertain parameters, such as the linear and cubic pitch stiffness coefficients are modeled as bounded random variables with λ-PDFs (probability density functions). With the aid of Gegenbauer polynomial approximation, the two-dimensional stochastic airfoil system is transformed at first into its equivalent deterministic one. Then the Hopf-bifurcation point is determined through the equivalent deterministic system, and the onset of the flutter, together with the flutter frequency against the probability density distribution parameter and the intensity of the random variable is explored. In addition, the ranges of the peak pitch and plunge responses against the flight speed and the PDFs of the peak pitch response are obtained. Numerical results show how the probability density distribution parameters and the intensities of random parameters affect the flutter onset speed, flutter angular frequency, the upper and lower boundaries of peak responses, and the PDFs of peak responses.     

我省高职高专院校图书馆现代技术应用情况调查

目的比较与探讨不同类型高职高专图书馆现代化技术应用情况方法采用自编问卷对部分高职高专图书馆进行调查结果高职高专图书馆情况差异较大二级学院、民办学院处于前列,新高职、高专、职工大学紧随其后,挂靠学院与普通中专正在崛起。     

1/spl phi/ 3W grid-connection PV power inverter with partial active power filter

This paper presents a single-phase three-wire (1/spl phi/ 3W) grid-connection photovoltaic (PV) power inverter with a of partial active power filter (PAPF) feature, which can not only deal with PV power but filter current harmonics and improve power factor. Once the processed power exceeds the switch ratings, the inverter can reduce its output reactive power and harmonic power, while still supplying the maximum real power generated by the PV arrays. In the derivation of control laws, a limit circle is defined to confine the output power of the inverter. To determine the power that the inverter can process, the instantaneous reactive power of a 1/spl phi/ 3W system is defined and used to calculate reactive power, which can avoid complex detections of phase angle and magnitude of the fundamental component of a nonlinear load current. Simulation results and experimental measurements have verified the proposed algorithm and the feasibility of the inverter.     

Aperture error mitigation via local-state estimation for frequency-based emitter location

This paper considers the problem of locating a stationary coherent emitter via a single moving platform making frequency measurements in the presence of aperture state uncertainty. It is shown that the estimated emitter location is most sensitive to the receiving aperture velocity uncertainty. The required aperture velocity accuracy is determined through a noninfinitesimal perturbation analysis. A solution to location accuracy enhancement with a minimal hardware addition is attempted. It is shown that this can be achieved by mounting a high-resolution tri-axis microelectromechanical systems (MEMS) accelerometer at the aperture to measure its velocity, which can deviate significantly from that estimated by the on-board navigation system. The Doppler shifts of the GPS signal carrier frequency, whenever it can be acquired through the aperture, are also considered as a way to aid the aperture velocity measurement. A decentralized, federated processing method for the aperture velocity estimate referenced at the aperture, integrating all measurement data, is presented. An upper bound for the error of aperture velocity estimate is derived. The potential for significant accuracy enhancement for emitter location is demonstrated.     

毕棚沟 一路走过

梦是对无限、永远的可能的相信，而现实并不……黑、白棋总是在棋盘上腾转挪移，而黑、白并不……[编者按]     

基于PCI总线的石英晶体元件电参数测试仪

首先介绍PCI总线控制专用芯片S5920的组成,Mailboxs、FIFO、Pass-Thru的基本概念、性能和使用方法。其次介绍测量石英晶体元件参数的阻抗计法和π网络法。对基于PCI总线控制器S5920为核心的π网络法石英晶体元件电参数测试仪的设计和实现作了说明。该方法测量的频率可达2005MHz。利用GPs高精度的授时信号作为频率校准信号校准信号源的精度。