State transition matrix is an important concept in modern control system. It studies the motion law of linear control system from initial state to any state at time t. In this paper, joining an engineering example, an...State transition matrix is an important concept in modern control system. It studies the motion law of linear control system from initial state to any state at time t. In this paper, joining an engineering example, an approach to determine zero-input responses is developed, and the design of simulation experiments with the aid of Matlab is used to illustrate the physical meaning of it. Furthermore, during the engineering application, for the discrimination of state transition matrix, a discrimination method of state transition matrix is proposed based on related theorems and an effective method is derived by calculating characteristics during tedious verification of theorem. The simulation results have proved the correctness of system analysis by using such discrimination method under different parameter models.展开更多
The temperature dependence of the density of energy states in semiconductors is considered. With the help of mathematical modeling of the thermal broadening of the energy levels, the temperature dependence of the band...The temperature dependence of the density of energy states in semiconductors is considered. With the help of mathematical modeling of the thermal broadening of the energy levels, the temperature dependence of the band gap of semiconductors is studied. In view of the non-parabolic and the temperature dependence of the effective mass of the density of states in the allowed bands, graphs of temperature dependence of the band gap are obtained. The theoretical results of mathematical modeling are compared with experimental data for Si, InAs and solid solutions of p-Bi2-xSbxTe3-ySey. The theoretical results satisfactorily explain the experimental results for Si and InAs. The new approach is investigated by the temperature dependence of the band gap of semiconductors.展开更多
为了实现接头载流量的准确计算,提出了一种基于ANSYS的高压交流电缆接头载流量确定方法.该方法以绝缘长期耐受温度为限制条件,利用接头轴向二维有限元仿真模型计算载流量.仿真结果表明,当对流散热环境和负荷都相同时,相同导体截面的电...为了实现接头载流量的准确计算,提出了一种基于ANSYS的高压交流电缆接头载流量确定方法.该方法以绝缘长期耐受温度为限制条件,利用接头轴向二维有限元仿真模型计算载流量.仿真结果表明,当对流散热环境和负荷都相同时,相同导体截面的电缆接头导体温度高于电缆本体的导体温度,接头的载流能力低于同导体截面电缆的载流能力.为验证仿真模型精度,设计了接头载流量实验平台,对不同负荷下110 k V电缆接头稳态温度分布进行了实测.仿真与实验结果的对比表明,当接头导体温度超过绝缘长期耐受温度时,应用接头轴向二维有限元仿真模型计算压接管处导体温度的误差不超过1.0%,仿真计算的准确度能够满足工程应用的需求.最后,采用二分法算得110 k V 630 mm^2电缆接头载流量为1220A,比相同导体截面电缆本体在相同环境条件下的载流量减少了17.79%.研究结果表明:采用接头轴向二维有限元仿真模型计算载流量是可行的.展开更多
基金Supported by the National Natural Science Foundation of China(11605147)the Education and Teaching Reform Project of Xianyang Normal University(2015Z006).
文摘State transition matrix is an important concept in modern control system. It studies the motion law of linear control system from initial state to any state at time t. In this paper, joining an engineering example, an approach to determine zero-input responses is developed, and the design of simulation experiments with the aid of Matlab is used to illustrate the physical meaning of it. Furthermore, during the engineering application, for the discrimination of state transition matrix, a discrimination method of state transition matrix is proposed based on related theorems and an effective method is derived by calculating characteristics during tedious verification of theorem. The simulation results have proved the correctness of system analysis by using such discrimination method under different parameter models.
文摘The temperature dependence of the density of energy states in semiconductors is considered. With the help of mathematical modeling of the thermal broadening of the energy levels, the temperature dependence of the band gap of semiconductors is studied. In view of the non-parabolic and the temperature dependence of the effective mass of the density of states in the allowed bands, graphs of temperature dependence of the band gap are obtained. The theoretical results of mathematical modeling are compared with experimental data for Si, InAs and solid solutions of p-Bi2-xSbxTe3-ySey. The theoretical results satisfactorily explain the experimental results for Si and InAs. The new approach is investigated by the temperature dependence of the band gap of semiconductors.
文摘为了实现接头载流量的准确计算,提出了一种基于ANSYS的高压交流电缆接头载流量确定方法.该方法以绝缘长期耐受温度为限制条件,利用接头轴向二维有限元仿真模型计算载流量.仿真结果表明,当对流散热环境和负荷都相同时,相同导体截面的电缆接头导体温度高于电缆本体的导体温度,接头的载流能力低于同导体截面电缆的载流能力.为验证仿真模型精度,设计了接头载流量实验平台,对不同负荷下110 k V电缆接头稳态温度分布进行了实测.仿真与实验结果的对比表明,当接头导体温度超过绝缘长期耐受温度时,应用接头轴向二维有限元仿真模型计算压接管处导体温度的误差不超过1.0%,仿真计算的准确度能够满足工程应用的需求.最后,采用二分法算得110 k V 630 mm^2电缆接头载流量为1220A,比相同导体截面电缆本体在相同环境条件下的载流量减少了17.79%.研究结果表明:采用接头轴向二维有限元仿真模型计算载流量是可行的.
