基于信号增强的缓慢泄漏检测方法

目前管道泄漏检测方法可有效检测突发泄漏，对于缓慢泄漏则存在检测灵敏度低、定位不准确等问题。基于此，提出了一种基于信号增强的缓慢泄漏检测方法。通过信号压缩（抽取及移位）克服缓慢泄漏压力信号下降平缓的缺点；根据声波信号具有波形尖锐突出、对突发泄漏敏感的优点，通过建立以压力为输入、虚拟声波为输出的声波信号变送器模型，将压力信号转换为声波信号，克服了泄漏压力信号容易被淹没在管道压力波动及背景噪声中的缺点，实现了缓慢泄漏信号的增强；利用临近插值方法重构虚拟声波信号，基于延时互相关分析实现了缓慢泄漏的准确定位。实验结果表明，该方法具有显著的信号增强效果和定位精度，实现了缓慢泄漏的准确检测。     

仪器仪表产品脉冲耐压试验要求和保护器件的选择

仪器仪表产品的脉冲耐压试验是产品型式试验、例行试验中的基本内容。通过对GB4793.1标准的整理,归纳了仪器仪表产品的脉冲耐压试验要求。通过对试验方法和设备特性的梳理,总结了特性参数,并介绍了应对脉冲耐压试验可采取的保护器件的类别及选用方法。     

用CPLD实现SRAM工艺FPGA的安全应用

提出了一种利用CPLD产生的伪随机码来加密SRAM工艺FPGA的方法,并详细介绍了具体的电路和VHDL代码。     

插补法CAI研究

数字程序控制计算机辅助教学是将计算机技术用于数字程序控制的教学过程，它帮助学生学习并模拟教学实验．本文介绍了数字程序控制中直线插补和圆孤插补的ＣＡＩ实现方法．     

VB中实现打印功能的方法

介绍了在VB开发的应用程序中,实现打印功能的几种方法.这些方法包括:①打印窗口;②通过PRINTER打印;③利用数据报表进行打印;④将打印内容传送于Office组件的Word或Excel,通过Word、Excel打印.同时列出了相关的程序格式.     

数字电视传输流的实时码率变换系统

数字视频压缩后通常是打包成传输流的形式进行传送，年个传输流有其固定的发送码率，在某些应用场合，比如信道调制前端，需要对输入传输流码率进行改变以适应该信道要求，描述了一种全硬件实现，双路输出，实时，节目可选择的码率变换系统的原理及具体实现。     

重视过程控制工程安装材料的选择

本文结合工程介绍了自动化仪表工程设计中常用安装材料的正确选择方法和选择不当可能造成的危害。     

A Refinement Calculus for Shared-Variable Parallel and Distributed Programming

Parallel computers have not yet had the expected impact on mainstream computing. Parallelism adds a level of complexity to the programming task that makes it very error-prone. Moreover, a large variety of very different parallel architectures exists. Porting an implementation from one machine to another may require substantial changes. This paper addresses some of these problems by developing a formal basis for the design of parallel programs in the form of a refinement calculus. The calculus allows the stepwise formal derivation of an abstract, low-level implementation from a trusted, high-level specification. The calculus thus helps structuring and documenting the development process. Portability is increased, because the introduction of a machine-dependent feature can be located in the refinement tree. Development efforts above this point in the tree are independent of that feature and are thus reusable. Moreover, the discovery of new, possibly more efficient solutions is facilitated. Last but not least, programs are correct by construction, which obviates the need for difficult debugging. Our programming/specification notation supports fair parallelism, shared-variable and message-passing concurrency, local variables and channels. The calculus rests on a compositional trace semantics that treats shared-variable and message-passing concurrency uniformly. The refinement relation combines a context-sensitive notion of trace inclusion and assumption-commitment reasoning to achieve compositionality. The calculus straddles both concurrency paradigms, that is, a shared-variable program can be refined into a distributed, message-passing program and vice versa. Received July 2001 / Accepted in revised form May 2002     

Running programs backwards: The logical inversion of imperative computation

Imperative programs can be inverted directly from their forward-directed program code with the use of logical inference. The relational semantics of imperative computations treats programs as logical relations over the observable state of the environment, which is taken to be the state of the variables in memory. Program relations denote both forward and backward computations, and the direction of the computation depends upon the instantiation pattern of arguments in the relation. This view of inversion has practical applications when the relational semantics is treated as a logic program. Depending on the logic programming inference scheme used, execution of this relational program can compute the inverse of the imperative program. A number of nontrivial imperative computations can be inverted with minimal logic programming tools.     

二阶A型Cooper变换的增强型

对二阶Ａ型Ｃｏｏｐｅｒ变换进行增强，放宽可用性条件，并证明了其正确性，最后举例说明其应用。