房屋建筑结构无损检测方法的分析与展望

通过对现有的结构无损检测方法的总结和分析,讨论了各种方法的优缺点.并结合现场测试的要求,展望结构检测技术的发展方向与趋势.     

企业经营理念的思考

在经营实践中,企业的灵魂是经营理念,成功的企业必有科学、合理的经营理念做指导,经营理念是企业生存发展的决定因素.     

Impact of temperature cycle profile on fatigue life of solder joints

In this paper the influence of the temperature cycle time history profile on the fatigue life of ball grid array (BGA) solder joints is studied. Temperature time history in a Pentium processor laptop computer was measured for a three-month period by means of thermocouples placed inside the computer. In addition, Pentium BGA packages were subjected to industry standard temperature cycles and also to in-situ measured temperature cycle profiles. Inelastic strain accumulation in each solder joint during thermal cycling was measured by high sensitivity Moire interferometry technique. Results indicate that fatigue life of the solder joint is not independent of the temperature cycle profile used. Industry standard temperature cycle profile leads to conservative fatigue life observations by underestimating the actual number of cycles to failure.     

热重分析对高分子材料中碳酸钙的定量研究

碳酸钙是高分子材料中常用的无机填料，在高温时会同二氧化碳而失重。利用热重分析可准确定出高分子材料中碳酸钙的含量，同时还可测出聚合物，挥发物的含量，热重分析法样品用量小，灵敏度高，所需时间短。     

玻璃两面重叠手印拍摄机理

根据斯涅尔定律和菲涅尔公式阐述清水衬底法消除玻璃下界面手印或玻纹的影像，以及用偏振光，紫外线拍摄玻面痕迹的方法和机理。     

基于遗传算法的水轮机最优工况参数计算

利用遗传算法计算水轮机的最优工况参数，给出遗传算法的具体实现步骤，并结合某电站的实际运行参数进行计算，结果表明，利用遗传算法计算水轮机的最优工况是可行的，而且寻优效率高，结果可靠。表2个。     

Wideband miniature G-shaped antenna for dual-band WLAN applications

A wideband miniature G-shaped coplanar waveguide fed dual-band antenna for a wireless local area network (WLAN) is proposed. The proposed antenna has good radiation pattern and can provide two separate measured impedance bandwidths of 0.55 GHz (about 22.9% centred at 2.42 GHz) and 2.85 GHz (about 50.9% centred at 5.60 GHz), so that it easily covers the required bandwidths for WLAN operation. This design results in a small antenna size of 22 times 18.5 mm with the ground plane regarded as part of the antenna structure.     

新型涂料增稠剂的化学成分鉴定

本文用红外光谱法对一种新型涂料增稠剂进行了化学成分鉴定,其主要成分为羟丙基甲基纤维素与蒙脱土。     

浅谈水利工程质量的宏观控制

本文从政府、建设单位、施工单位三方面对如何搞好水利工程质量进行分析,并提出如何提高工程质量问题。