Modeling electromigration lifetime under bidirectional currentstress

Electromigration reliability of interconnect under bidirectional current stress has been studied in a wide frequency range (mHz to 200 MHz). Experimental results show that the AC lifetime rises with the stress current frequency. The current density exponent and the activation energy of AC lifetime are found to be twice that of DC lifetime. Pure AC current stress failure at extremely high current density is believed to result from thermal migration of metal at hot/cold transition points     

Mathematical simulation and experimental verification of melting resulting from the coupled effect of natural convection and exothermic heat of mixing

When melting processes are associated with an exothermic heat of mixing, unique coupled transport phenomena take place. In this article, a mathematical model has been developed to simulate these unique coupled heat and mass transfer events. The model was based on the control-volume finite difference approach and on an enthalpy method. In order to verify the mathematical model, a low-temperature physical model was established consisting of ice and sulfuric acid solutions. In this physical model, both temperature and velocity measurements were carried out. The model predictions were compared with experimental measurements, and they were found to be in good agreement. The model was also applied to a high-temperature system, namely, the melting of silicon metal in liquid high carbon iron. The predictions distinguished two periods present in the entire melting process. In the first period, the silicon was heated up. The second period, i.e., free melting period, occurred in tandem with the exothermic reaction, and consequently, the melting process was greatly accelerated. As was the case with the low-temperature physical model, as with the high-temperature system, good agreement was obtained between the predicted results and the experimental measurements.     

Detection of congenital müllerian duct anomalies using three-dimensional ultrasound

PURPOSE: The purpose of this study was to assess the value of 3-dimensional sonography in the diagnosis of congenital müllerian duct anomalies, which cause infertility, preterm labor, and first trimester abortion. METHODS: A prospective study was undertaken in which 40 patients with histories of repeated spontaneous abortions or infertility were first examined using conventional 2-dimensional sonography or hysterosalpingography. Three-dimensional transvaginal sonography was then performed. RESULTS: Twenty-eight women had müllerian duct abnormalities, and 12 women had normal uterine anatomy. Müllerian duct defects detected in this study were unicornuate uterus (3), bicornuate uterus (3), complete or partial septate uterus (12), arcuate uterus (9), and didelphic uterus (1). The diagnosis of müllerian duct anomalies in these patients was confirmed by laparoscopic and/or hysteroscopic examinations. Three-dimensional sonography demonstrated all congenital uterine abnormalities with a sensitivity and specificity of 100%. Separate uterus and bicornuate uterus could be correctly diagnosed using 3-dimensional sonography in 11 (92%) of 12 cases and 3 (100%) of 3 cases, respectively. These 2 abnormalities were commonly confused with each other using hysterosalpingography and conventional sonography. CONCLUSIONS: Three-dimensional sonography with image reconstruction is less expensive and less invasive than hysterosalpingography for the assessment of uterine anatomy and diagnosis of müllerian duct abnormalities. The ability to visualize both the uterine cavity and the myometrium on a 3-dimensional scan facilitates the diagnosis of uterine anomalies and enables the differentiation of septate from bicornuate uteri for preoperative surgical planning.     

中国的三种非同步轨道卫星移动通信系统星座方案

本文介绍基于我国的三种非同步轨道卫星移动通信系统星座方案：低、中轨系统各有２４和１８颗星，轨道高度分别为１３２６和８０３５ｋｍ，两系统各以５°和３０°的仰角对我国的覆盖率为９９．７８％和９９．９６％；椭圆轨道系统１２颗星，近、远地点分别为４２７和２９０６ｋｍ，以７°和１５°仰角对我国北纬２０°以上地区覆盖率分别为９７．９０％和８９．６１％，若增加４颗中轨卫星，以１５°仰角对我国的覆盖率为９９．９９％。     

B－ISDN与现有网络互连的研究

本文主要围绕Ｂ－ＩＳＤＮ与现有各种网络（如ＰＳＰＤＮ、ＰＳＴＮ、ＬＡＮ等）的互连问题展开讨论，并针对不同的应用场合提出了相应的互连解决方案。     

Cluster analysis in industrial market segmentation through artificial neural network

Market segmentation has commonly applied cluster analysis. This study intends to make the comparison of conventional two-stage method with proposed two-stage method through the simulated data. The proposed two-stage method is the combination of self-organizing feature maps and K-means method. The simulation results show that the proposed scheme is better than the conventional two-stage method based on the rate of misclassification.     

测井数据实时采集与接口设计

介绍了一种采用改进型的ＣＬＳ３７００数控测井系统对微电阻率扫描仪数据采集与控制接口的设计及实现方法。基于ＣＬＳ３７００数控测井仪和ＦＭＳ仪采用８９Ｃ５１单片机设计出通信接口，解决了微电阻率方法。基于ＣＬＳ３７００数控测井仪和ＦＭＳ仪采用８９Ｃ５１单片机设备出通信接口电路，解决了微电阻主扫描仪现现场实时处理中的瓶颈问题。     

分子振动态及其跃迁的激光相干控制

讨论了激光合成相干叠加态的原理及其性质 ,针对 XY2 型分子 ,证明了合成局域模振动的可行性 ,然后给出相干叠加态的跃迁几率特征 ,发现它仍表现出相干的特性 ,对之进行分析研究表明 ,分子的振动态具有可控性 ,态跃迁几率具有可控性。