Low cycle fatigue behavior of a eutectic 80Au/20Sn solder alloy

The eutectic 80Au/20Sn solder alloy is widely used in high power electronics and optoelectronics packaging. In this study, low cycle fatigue behavior of a eutectic 80Au/20Sn solder alloy is reported. The 80Au/20Sn solder shows a quasi-static fracture characteristic at high strain rates, and then gradually transforms from a transgranular fracture (dominated by fatigue damage) to intergranular fracture (dominated by creep damage) at low strain rates with increasing temperature. Coffin-Manson and Morrow models are proposed to evaluate the low cycle fatigue behavior of the 80Au/20Sn solder. Besides, the 80Au/20Sn solder has enhanced fatigue resistance compared to the 63Sn/37Pb solder.     

校园网宿舍网络管理模式的探讨

讨论了高校学生宿舍区网络的特点，结合天津商学院校园网的实践，讨论了校园网宿舍网络管理的模式。     

利用新型场效应管(QFET)的正向变换器

介绍了单端正向变换器基本电路，重点叙述带三路调节DC电压的100KHZ180W离线电源。它采用具有低导电阻RDS和低栅极电荷Qg的新型场效应管（QFET）作为变换电路的主开关器件，降低了电源开关损耗并提高了效率3%-5%。     

基于16位单片机的电磁平板硫化机控制系统

介绍一种基于 16位单片机的电磁平板硫化机控制系统,该系统能有效地提高现场控制的实时性和程序运行的稳定性     

用保护共沉淀法制备纳米ZrO2(Y2O3)粉体

用Tween-80保护共沉淀法制备了ZrO2(Y2O3）纳米粉体，用差热分析，热重分析，X射线衍射及透射电子显微镜等技术研究所了粉体的特征，结果表明：在700℃燃烧0.5h后ZrO2(Y2O3)粉体的平均粒径为3－9nm，比表面为128.5-134.5m^3g^-1,在1250℃煅烧8h后ZrO2(Y2O3)粉体已完全形成了立方相的ZrO2L大溶体，并且有非常好的烧结性能。     

智能化通信电源监控系统

以80C552单片机为核心,介绍了一种实现智能化电源监控系统的软、硬件设计。     

Optimal estimation of parameters of dynamical systems by neural network collocation method

In this paper we propose a new method to estimate parameters of a dynamical system from observation data on the basis of a neural network collocation method. We construct an object function consisting of squared residuals of dynamical model equations at collocation points and squared deviations of the observations from their corresponding computed values. The neural network is then trained by optimizing the object function.The proposed method is demonstrated by performing several numerical experiments for the optimal estimates of parameters for two different nonlinear systems. Firstly, we consider the weakly and highly nonlinear cases of the Lorenz model and apply the method to estimate the optimum values of parameters for the two cases under various conditions. Then we apply it to estimate the parameters of one-dimensional oscillator with nonlinear damping and restoring terms representing the nonlinear ship roll motion under various conditions. Satisfactory results have been obtained for both the problems.     

静止同步串联补偿电源的控制与驱动电路的设计

介绍了一种新型的串联补偿电源(SSSG)，提出了基于80C196MC的波形发生器来设计SSSG的控制器与驱动电路，能够准确、灵活地产生所需电压，连续、平滑地补偿容性、感性无功功率等系统参数，并设计组成单相SSSG系统，进行实验系统试验与调试达到了预期的目的。     

基于RTLinux和AD2S80A的角位置测量系统设计与实现

基于RTlinux和AD2S80A的角位置测量系统,选用旋转变压器和感应同步器作为测量系统的传感器,利用AD2S80A轴角变换器将两种测量传感器输出的模拟信号转换为相应的数字信号。根据双通道测角系统粗精耦合的原理,在RTLinux嵌入式系统中对两种数字信号进行耦合处理,并对耦合后信号的进行补偿处理,实现角位置的高精度测量。检测数据表明,这种测量系统可以实现以内的测量精度。