低频靶标法测量CCD相机调制传递函数的仿真

基于用高频靶标法测试调制传递函数（MTF）时不能准确地体现出CCD器件的平均采样的情况。该文探讨用低频靶标法测试MTF，介绍它的原理；通过数字仿真CCD的光学镜头的模糊和采样平均过程，分析不同频率靶标的MTF测试结果，并分析相位造成的影响。     

Increase in fish abundance during two typhoons in the South China Sea

A fish monitoring program was conducted in the northern region of the South China Sea from March 2009 to December 2010. During this period, two typhoons, GONI and Koppu, hit this region consecutively in August and September 2009. The fish and satellite data were analyzed to understand the influence of the typhoons on fish activities. The results showed that the fish species number (FSN) increased by approximately 14.29% and 14.81% after the two typhoons, GONI and Koppu, respectively. The five increased fish species included three estuarine species and two shallow sea species. However, one shallow sea species was also absent. In the nearshore (near the Pearl River Estuary) and offshore (along the typhoon’s track) regions after GONI, the FSN increased by approximately 24% (nearshore) and 52.63% (offshore), with estuarine species accounting for 42.86% (nearshore) and 33.33% (offshore) of the fish species; after Koppu, the FSN increased by approximately 15.38% (nearshore) and 163.64% (offshore), with estuarine species accounting for 60% (nearshore) and 26.32% (offshore) of the fish species. In the increased records, small and medium-sized fish species were dominant nearshore, and small fish species were dominant offshore. The FSN increased to a maximum value between the 5th and the 10th days after the typhoon nearshore and between the 3rd and 8th days after the typhoon offshore. The results indicated that river discharge, triggered by the typhoon’s nearshore rainfall, as well as offshore upwelling nutrients, also triggered by the typhoons, and may have played important roles in the variability of fish species. This research found that the increase in the FSN was associated with the typhoons in the northern South China Sea.     

论超声速流动中的有益干扰

本文利用三维超声速流动线化理论的积分特性,推出了点源分布和单元旋涡分布的积分关系公式,并利用它们分析了翼下有体,翼上有体和翼的上、下各有一个体等型式的干扰特点,指出了几种可能的有益干扰型式。     

航空发动机试车数据采集与处理系统

本文介绍一个以微型计算机为中心的试车数据采集与处理系统。该系统具有稳态和动态采集与处理的双重功能。系统使用高速采集硬件,用PL/M语言编写采集和处理程序,采集速度达5000次/秒以上。稳态压力采集使用自行研制的计算机控制扫描阀,并运用了实时校准技术。温度信号的线性化处理使用变权自动分段多项式拟合法求出的热电偶回归方程。系统硬件采取了一系列抗干扰措施,程序中安排了软件滤波。为保证试车安全,采取了计算机报警。     

线切割断丝先兆及原因

断丝问题是线切割加工的一个严重问题,对加工速度和加工表面完整性都有很大影响。近10年来国内外对断丝问题做了很多研究。本文利用高速数据采集系统记录了大量的断丝前放电脉冲波形,分析找出了断丝的先兆信号和断丝的原因。     

翼-身组合体跨音速守恒型全位势流AF2高效算法的应用

 本文用Joukowski交换将圆截面机身的每一横截面逐一转绘为垂直切缝,因而将翼-身组合体转绘为某单独机翼。我们用作者采用过的数值保角转绘法对转换的单独机翼生成O型贴体坐标网格,然后用逆转绘构造翼-身组合体绕流的O型贴体坐标网格。跨音速计算采用守恒型金位势方程,精确边界条件和AF2高效有限差分迭代算法。本文指出,只需少量修改,就可将单独翼分析程序扩展为可同时适用于翼-身组合体。本文考虑的组合体其机身为有限或无限长,圆形截面,机翼前后机身轴线允许弯曲;机翼有任意平面形状,但翼尖弦长不能太短。     

边条翼作俯仰运动时翼面吹气的作用

在３ｍ低速风洞中通过测力与微丝显示方法，研究了在边条翼的边条和主翼上吹气对机翼作大攻角快速俯仰运动时空气动力特性的影响，同时还研究了在不同迎角下开始吹气的作用。结果表明，翼面吹气能有效提高机翼的非定常气动特性和缩小机翼的非定常气动特性迟滞回环，特别是在小迎角下开始吹气效果较好。     

跨声速机翼的设计计算方法

本文介绍一种三维跨声速机翼设计计算方法,它以跨声速小扰动理论为基础,以给定的压力分布与分析计算的压力分布之差作为目标函数,应用Green定理建立起目标函数与机翼剖面形状修改量的线性代数方程组,从而求解出翼剖面的修改量,加到原来机翼各剖面上,再用分析计算程序计算,经过多次的反复,就可以达到设计目标。本方法的特点是分析计算程序与设计程序相对独立,只作小量修改就可联合使用。本文介绍用此方法设计的两个算例,说明设计结果是好的,计算机时与其它方法相比是大大缩短了。     

试论股份制的生命力——资本增殖效应

本文对股份制的原理进行了详细阐述,并对股份制的生命力之所在——“资本增殖效应”作了分析。     

印制电路板在线故障诊断系统

介绍了两类印制电路板在线故障诊断系统及其特点。给出了目前市场上流行的印制电路板在线故障诊断系统,并提出了选购的要点。