Stirling-type pulse tube refrigerator (PTR) with cold compression: Cold compressor,colder expander

This research paper focuses on the performance prediction and its validation via experimental investigation of a Stirling-type pulse tube refrigerator (PTR) equipped with a cold linear compressor. When the working gas is compressed at cryogenic temperature, the acoustic power (PV power) can be directly transmitted through the regenerator to the pulsating tube without experiencing unnecessary precooling process. The required PV power generated by the linear compressor, furthermore, can be significantly diminished due to the relatively small specific volume of the working gas at low temperature. The PTR can reach lower temperature efficiently with higher heat lift at the corresponding temperature than other typical single-stage Stirling-type PTRs. Utilizing a cryogenic reservoir as a warm end and regulating the entire operating temperature range of the PTR will enable a PTR to operate efficiently under space environment.In this research, the experimental validation as a proof of concept was carried out to demonstrate the capability of PTR operating between 80 K and 40 K. The linear compressor was submerged in a liquid nitrogen bath and the lowest temperature was measured as 38.5 K. The test results were analyzed to identify loss mechanisms with the simple numerical computation (linear model) which considers the dynamic characteristics of the cold linear compressor with thermo-hydraulic governing equations for each of sub components of the PTR. All the mass flows and pressure waves were assumed to be sinusoidal.     

基于JPEG2000的雷达卡技术研究

介绍了一种应用目前最新静态图像压缩算法JPEG2000实现的雷达卡的方法,首先说明了雷达卡的硬件实现平台;接着重点说明JPEG2000压缩算法,在JPEG2000编码器里详细说明了DC层进和分量变换、离散小波变换、内嵌编码与最佳截断这三大要点,并给出了相应的程序流程图;再说明了JPEG2000算法从PC到DSP的移植与优化;最后给出了雷达图像采集压缩系统的性能测试。     

基于PTR2000的步进电机无线控制系统

介绍了一种基于无线射频模块PTR2000构成的步进电机远距离无接触控制系统,实现了对步进电机的无线控制,为步进电机的应用提供了参考.     

高校计划财务处信息发布系统的实现

该文讨论了高校计划财务处信息发布系统的结构形式,并给出了该系统的工作原理以及所采用关键技术的解决方法。     

基于WEB的教学改革研究项目管理系统设计与实现

本文针对莆田学院现在教改研究项目管理方式的不足,设计并实现了局域网内基于WEB的教学改革研究项目管理系统。     

基于JPEG2000的码率控制算法的研究

码率控制是JPEG2000编码的重要过程,其算法的优劣直接决定着整个编码效率的高低和压缩图像质量的好坏.针对JPEG2000标准建议的码率控制算法的计算复杂度高且占用存储空间大的问题,提出了对隔行扫描编码通道算法ACPI的一种改进算法,包括添加估计斜率值阶段、逆转扫描分辨率水平顺序,以及逆转同等级子带扫描的顺序.实验结果表明,该算法有效地减少了一JPEG2000的计算复杂度和存储量,提高了性能.     

AutoCAD 2000 Visual LISP ActiveX编程技术

Ｖｉｓｕａｌ ＬＩＳＰ不但提供了完全可视化的代码编写、调试环境,而且还可以利用先进的ＡｃｔｉｖｅＸ和事件反应器技术,使其比传统的ＡｕｔｏＬＩＳＰ开发的软件更具智能化、运行更为迅速。对ＡｃｔｉｖｅＸ技术在Ｖｉｓｕａｌ ＬＩＳＰ编程中的应用方法作了详细地介绍并附以相应的应用实例。     

Windows 2000公钥体系结构

介绍了Ｗｉｎｄｏｗｓ２０００公钥体系结构及其在电子商务中应用。ＰＫＩ的标准在不断发展,成为电子商务应用的必需技术。Ｗｉｎｄｏｗｓ２０００的ＰＫＩ体系以其新特点,将成为电子商务的理想平台     

Evolutionary Computation in Structural Design

The paper provides the results of preliminary research on the application of evolutionary computation to integrated structural design in which a complex design support tool automatically conducts both conceptual and detailed design. In the paper, a brief overview of the state of the art in evolutionary computation and its applications to structural design is provided. Next, Inventor 2000 is described, a unique research and structural design tool developed by the authors at George Mason University that combines an evolutionary computation component with a system for wind forces analysis, and a system for the analysis, design and optimisation of steel structures. The paper also presents the results of four structural design experiments conducted with Inventor 2000. The objective of experiments was to investigate various forms of evolutionary computation as applied to structure design. Finally, the paper provides the initial research conclusions and recommendations for further research.     

Office 2000组件的对象模型及应用

本文建立了Office2000组件中对象的层次结构模型,阐述了Office对象、方法及其属性的概念,并结合实际应用提出了实现其访问控制的编程模式。