微型可编程控制器温度测控系统

本文叙述了一个由微型可编程控制器ＩＰ－１６１２构成的温度测控系统，在介绍ＩＰ－１１６１２ＰＬＣ特性的基础上，讨论了用它构成温度测控系统的基本原理、电路结构和编程方法。最后提出有关ＰＬＣ应用问题的几点看法。     

贩毒吸毒的微分方程模型及定性分析

贩毒吸毒是人类丑恶行为表现出的社会丑恶现象，在人类正常的生活环境中时有发生。特别近年来有的国家或地区呈现流行的趋势，各国对此都十分关注。建立三个描述贩毒吸毒社会丑恶现象的微分方程模型。借助于微分方程定性论的基本理论，分析微分方程模型基本理论，分析贩毒吸毒流行的趋势，流行的结局，得到基本符合实际的效果。     

确定高速碰撞试验中碎片特性的测试技术

文章介绍了高速碰撞试验中碎片特性的几种测试技术,软捕获技术、照相技术、间接测量技术,及其适用情况。     

ACARS原理分析

本文着重分析了 ACARS 工作原理,论证了调制体制的优越性,对微机控制下链信息发射的软件流程进行了模拟设计。     

计算机辅助绘制电子线路图

本义介绍在IBM 4300系列机上实现的、一种用于绘制电子线路图的应用软件,除能绘制表示各种元器件的符号图形外,还具有较强的图形编辑功能,例如可对图形作平移、复制和删除等操作。绘图采用菜单工作方式,操作很简便。程序用FORTRAN语言编写,采用模块结构,便于修改、功能充扩和移植。     

离心配重类零组件的离心试验技术探讨

介绍了离心配重零组件的工作原理,离心试验器的原理及结构,气浮式测速试验器的精度分析及优缺点、校准,离心配重块试验用标准件的形式及试验时应注意的问题及解决办法。     

Fracture behavior and self-sharpening mechanisms of polycrystalline cubic boron nitride in grinding based on cohesive element method

Unlike monocrystalline cubic boron nitride (CBN), polycrystalline CBN (PCBN) shows not only higher fracture resistance induced by tool-workpiece interaction but also better self-sharpening capability; therefore, efforts have been devoted to the study of PCBN applications in manufacturing engineering. Most of the studies, however, remain qualitative due to difficulties in experimental observations and theoretical modeling and provide limited in-depth understanding of the self-sharpening behavior/mechanism. To fill this research gap, the present study investigates the self-sharpening process of PCBN abrasives in grinding and analyzes the macro-scale fracture behavior and highly localized micro-scale crack propagation in detail. The widely employed finite element (FE) method, together with the classic Voronoi diagram and cohesive element technique, is used considering the pronounced success of FE applications in polycrystalline material modeling. Grinding trials with careful observation of the PCBN abrasive morphologies are performed to validate the proposed method. The self-sharpening details, including fracture morphology, grinding force, strain energy, and damage dissipation energy, are studied. The effects of maximum grain cut depths (MGCDs) and grinding speeds on the PCBN fracture behavior are discussed, and their optimum ranges for preferable PCBN self-sharpening performance are suggested.     

基于左矩阵分式模型的模态参数识别方法

提出一种多输入多输出(MIMO)系统的宽频模态参数识别算法。该方法基于频响函数(FRF)的左矩阵分式模型(LMFD),通过最小二乘法在z域内求解模态参数,避免了s域内矩阵的病态问题。针对左矩阵分式模型的特点,给出了一种通过主分量分析(PCA)建立稳定图的方法。指出了传统的频域多参考点(PRFD)方法与基于左矩阵分式模型识别方法之间的关系。最后采用GARTEUR模型仿真算例与飞机模型的实测算例对所提出的方法进行了验证,结果表明该方法具有良好的识别效果。     

Reliability Analysis of Aircraft Condition Monitoring Network Using an Enhanced BDD Algorithm

The aircraft condition monitoring network is responsible for collecting the status of each component in aircraft. The reliability of this network has a significant effect on safety of the aircraft. The aircraft condition monitoring network works in a real-time manner that all the data should be transmitted within the deadline to ensure that the control center makes proper decision in time. Only the connectedness between the source node and destination cannot guarantee the data to be transmitted in time. In this paper, we take the time deadline into account and build the task-based reliability model. The binary decision diagram (BDD), which has the merit of efficiency in computing and storage space, is introduced when calculating the reliability of the network and addressing the essential variable. A case is analyzed using the algorithm proposed in this paper. The experimental results show that our method is efficient and proper for the reliability analysis of the real-time network.