Calcination of Slags for Electroslag Remelting

The hydrides in industrial lime,alumina,magnesia,and calcium fluoride were investigated through differential thermal analysis and X-ray diffraction,and their mass losses during heating up were studied by thermogravimetric analysis method.The results indicate that the industrial alumina,lime,and magnesia,which have more moisture or hydride and mainly include γ-Al2O3,Ca(OH)2,and Mg(OH)2,lose more mass during thermogravimetric analysis process.However,the mass of premelted slag consisting of lime,fluorite,alum...     

GEM探测器的计数性能研究

采用真空热蒸发法在50μm的聚酰亚胺薄膜上蒸镀5μm~8μm的铜层,并用激光掩模打孔法在其上制备了孔径80μm、孔间距285μm的GEM复合薄膜,成功组装了20mm×20mm的GEM探测器。对GEM探测器在55Fe X射线(5.9keV)辐照下进行了脉冲幅度分布谱测试,讨论了漂移区电场、ΔGEM电场、收集区电场对探测器记数的影响。结果表明,随着漂移区电场的增加,计数先增加后减小,在13kV/cm时达到最大值9.7×104。随着ΔGEM电场的增加,记数呈指数增长,最大可达1.2×104。随着收集区电场的增加,计数增大并趋向饱和,最大可达1.3×105。     

Mitigation of Damages to Electric Utilities Due to High Winds

Extreme winds, hurricanes, and tornadoes produce significant damage to electrical transmission and distribution line structures. The damage produces loss of power to the affected communities for a variable length of time, depending on severity of damage. Most institutions whose operations would be life threatening in the event of power failure have emergency power. However, loss of power to both residences and businesses can have economic impact on the community in the form of temporary housing shortages and loss of business. Utility companies seem to cope with wind damage fairly well, following risk management procedures in designing for wind and in providing alternate routing for distribution lines. However, continuing research and developments are needed to keep abreast of the problem.     

X90管线钢中残余奥氏体含量测量的XRD与磁性法比较

 以X90管线钢为研究对象,通过X射线衍射对其横截面、纵截面以及轧面不同位置处的残余奥氏体含量进行了分析,讨论了在不同位置处XRD残余奥氏体含量测量结果存在较大差异的原因,并就磁性法与XRD法在测量残余奥氏体含量方面的异同进行了对比。结果表明：在横截面上XRD残余奥氏体含量的测量值远远高于纵截面及轧面处;样品的横截面上存在明显的择优取向,而在纵截面、轧面处取向分布较均匀,择优取向不明显;XRD法测残余奥氏体含量受择优取向的影响较大,而磁性法不受择优取向的影响。     

In-Situ Observation of SiC Bulk Single Crystal Growth by XRD System

In-situ analysis for SiC bulk single crystal growth was reported using vertical X-ray diffractometer system. A furnace for SiC sublimation growth combined with the XRD system which possessed three kinds of functions including topography, rocking curve measurement and crystal growth rate monitoring was developed. These functions could contribute as a powerful tool finding the optimum growth condition by dynamic observation in the crucible. In this study, the in-situ X-ray topographs succeeded to capture dynamic elongation of defects and dislocation generated in the SiC growing crystals. The in-situ rocking curve measurement reviled appearance of mosaic structure in the SiC crystal grown with high growth rate. The in-situ growth rate monitoring also succeeded very precisely using the direct X-ray beam absorption. On the base of findings and facts obtained by the in-situ observations, the importance for the SiC growth was discussed.     

Optimal tracking control for automatic transmission shift process

In order to improve the shift quality, a linear quadratic optimal tracking control algorithm for automatic transmission shift process is proposed. The dynamic equations of the shift process are derived using a Lagrange method. And a powertrain model is built in the Matlab/Simulink and verified by the measurements. Considering the shift jerk and friction loss during the shift process, the tracking trajectories of the turbine speed and output shaft speed are defined. Furthermore, the linear quadratic optimal tracking control performance index is proposed. Based on the Pontryagin's minimum principle, the optimal control law of the shift process is presented. Finally, the simulation study of the 1-2 upshift process under different load conditions is carried out with the powertrain model. The simulation results demonstrate that the shift jerk and friction loss can be significantly reduced by applying the proposed optimal tracking control method.     

抛物线型有损传输线频域灵敏度分析的伴随方程法

提出了一种求解含抛物线型有损非均匀线网络频域灵敏度的方法。该方法首先将抛物线型有损非均匀线用科罗达(Kuroda)等效方法变换成有损均匀线及若干集中元件组成的等效电路,然后借助伴随网络方程法求出抛物线型有损非均匀传输线等参数的频域灵敏度。给出了计算实例,并通过扰动法进行了验证。     

嵌入式TCP/IP技术研究及应用

针对单片机远程数据传输问题,基于8位单片机AT89C51和网卡芯片RTL8019As,将TCP/IP协议简化成面向硬件的形式,嵌入到单片机中,实现了单片机与Internet之间的电子邮件传输,提高了单片机与互联网之间的信息共享程度。     

综合负荷动静比例对电网传输功率的影响分析

电力系统仿真计算中,综合负荷的动态和静态成分所占比例对电网的暂态极限有着重要的影响。文章根据湖南电网的实际特点和电网结构以及运行情况,研究了综合负荷模型中不同感应电动机比例对湖南电网南北断面南送功率传输极限的影响,分析了综合负荷模型与恒阻抗加恒功率的静态负荷模型应用于湖南电网对断面南送功率极限的不同影响,并在此基础上分析了综合负荷模型和参数变化对电力系统稳定水平影响的机理,最后对湖南电网负荷模型和参数的选取提出了建议。     

一种微带准椭圆函数带通滤波器的研制

带有一对传输零点的准椭圆函数滤波器相比切比雪夫型滤波器具备更好的选择性。采用Levy等人提出的一种滤波器近似综合方法,结合微波场仿真软件,实现了对8附准椭圆函数滤波顺的精确设计,加工和实测结果表明了该方法的有效性,完全可以满足工程需求。