时序逻辑电路的仿真实验方法探析

应用PSpice对时序逻辑电路进行了仿真实验方法的探究,说明了 PSpice能快速、准确地分析数字电路的逻辑功能,对数字电路及其实验教学具有重要的辅助作用.     

无功调差及自动检测实验装置电路设计

从发电机和高压输电线供给的无功功率,一般满足不了负荷的需要,为了改变发电机外特性曲线,使并列运行的各台机组之间合理分配无功负荷并维持系统某一点电压恒定,在负荷变化时,需设置无功调差电路,补偿电力网电压损耗.分析了无功调差电路原理及自动检测比较回路的实现方法.     

一种915MHz零中频接收电路设计

与超外差接收电路相比,零中频接收电路结构简单,易于集成实现小型化,无镜频干扰,能省去昂贵且难以集成的镜频抑制滤波器,信道选择在低频进行,只需使用低通滤波器。但直流漂移、本振泄漏、低频噪声这些零中频结构固有的缺陷却使人们实现零中频的尝试不断失败。本文在某915MHz频段移动通信终端接收电路设计中,通过对这些缺陷的分析,提出对零中频结构的两处改进措施,用以抑制直流漂移、本振泄漏和低频噪声,完成了915 MHz零中频移动通信终端接收机的仿真设计。通过仿真软件ADIsimRF和ADS的计算与仿真,理论上验证了其可行性和科学性。     

基于电流模电路的CMOS模拟乘法器设计

以基本电流模电路为基础,分别对两种常用工艺,即双极性和CMOS工艺的电流平方电路进行了分析。它们分别由跨导线性环和电流镜基本电路构成。主要对CMOS器件构成的电流平方电路进行了设计与分析。最后设计了一种以MOS电流平方电路为主要模块的乘法器电路,实现了电流信号的相乘运算,并通过仿真验证了结果的正确性。     

一种新的模拟电路故障诊断方法研究

针对传统模拟电路检测方法难以发现器件缺陷的问题,提出了一种基于小波分析与人工神经网络的故障检测方法,选取典型滤波器电路。使用MATLAB进行仿真。仿真结果表明,此方法能够有效地识别故障器件,且诊断率高。     

未拆/已拆电子元器件的废旧印刷线路板浸铜规律对比研究

以未拆和已拆电子元器件的废旧印刷线路板(Waste Printed Circuit Boards,WPCBs)为研究对象,对比研究了其在硝酸中金属铜的浸出规律。研究结果表明:两者铜的浸出率随粒径的增大、时间的延长和固液比的减小而增大,温度对两者的影响都不大。已拆电子元器件的WPCBs的铜浸出率随H2O2和HNO3用量的增大而增大,而后者在实验讨论的范围内,H2O2和HNO3用量对其浸出率无明显影响。对于1 g样品,当未拆电子元器件的WPCBs粒径为0.25～0.5 mm,固液比为1:1,H2O2和HNO3均为2 mL时,50℃浸出2 h,即可浸出几乎全部的铜;当已拆电子元器件的WPCBs粒径为0.1～0.25 mm,固液比为1:1,H2O2和HNO3用量分别为2 mL和6 mL时,室温浸出2 h,铜浸出率达92.03%。     

燃机叶片温度分布特征的研究

为了更好的监测叶片的工作状况,对工作叶片温度分布特征进行研究.根据采集的温度数据分析叶片在工作中温度的变化趋势,总结周期与峰值的变化.采用等间距的叶片分割算法提取单一叶片的采集数据,建立温度分布的数学模型,为叶片温度的检测提供依据.     

交流伺服系统检测电路的研究

检测电路是交流伺服控制系统的重要组成部分,由电流、电压及位置检测电路组成,完成系统信号如电机的直流母线电压、电机的定子相电流、电机转子的位置等获取工作．分别设计了电机定子相电流的采集电路及处理方法、电机直流母线电压采集电路及电机转子位置检测电路与初始位置定位方法,并对设计的电路进行了实验分析．模拟实验结果表明整个系统具有较好的动态响应和稳态精度,从而验证了文中设计的检测电路的可行性．     

幂函数剖面薄圆环振子的扭转振动特性

对剖面厚度按幂函数变化的薄圆环振子的扭转振动进行了理论分析,导出了其等效电路;进而由等效电路得出了扭转振动频率方程及共振频率表达式;探讨了环形振子第1、第2阶共振频率及角位移放大系数与其半径比的关系;给出了薄圆环振子第1、第2阶共振频率及放大系数与其半径比的拟合关系曲线．通过有限元（FEM）模态的分析,表明理论结果与FEM仿真结果吻合,对环形扭转振子的工程设计具有参考价值．     

Concentrations and gas-particle partitioning of PCDD/Fs in the urban air of Dalian, China

PCDD/Fs in the urban air of Dalian,China were monitored with high-volume active sampler from November 2009 to October 2010.The concentration of Cl 4-8 DD/Fs ranged from 3065 to 49538 fg m-3,with an average of 10249 fg m-3.The international toxic equivalents(I-TEQ) value of that was 61.8 1182 fg m-3,with an average of 235 fg m-3,which was comparable to those in the other urban locations around the world.It was found that the Cl 4 8 DD/Fs appeared to be present mainly in the particle phase during winter,spring and autumn,while during summer which were dominantly in gas phase.The ratio of Cl 4-8 DD/Fs present in particle phase increased with the increasing level of chlorination.The concentrations of PCDFs and PCDDs decreased with the increase of chlorinated level,while the concentrations of 2,3,7,8-PCDDs congeners increased with the increase of chlorination level.The homolog profiles of the concentrations of PCDFs presented were higher than those of the PCDDs,which indicated the PCDD/Fs pollution source of the air in Dalian was characteristic for thermal source pollution.The correlation analysis of meteorological parameters with the concentrations of Cl 4-8 CDD/Fs was conducted using SPSS packages,and it was found that the ambient temperature and atmospheric pressure were important factors influence the concentration of PCDD/Fs in the air.The respiratory risk and intake dioxins of the residents around the sampling sites were studied in the paper.It was found that Junge-Pankow model was much more accurate in predicting the gas-particle partitioning behavior of PCDD/Fs homologues during winter,while the Harner-Bidleman model shows better agreement with the measured data during winter and summer.