基于Bode''''s integrals的PID控制器的设计及其仿真

该文为一类稳定的最小相位控制对象提出一种新的PID控制器的参数整定方法。它是基于Bode’s integrals可以给出最小相位稳定系统的幅值与相位的关系，从而运用bode’s integrals近似表示控制对象G（jw）的幅值和相位的微分，然后将该简化结果用于PID控制器的设计中，从而得到新的控制器参数整定方法。该文中PID控制器的设计要求是，调整控制对象的Nyquist曲线在给定频率处的斜率，以提高闭环系统性能。最后，通过在matlab中对一类稳定的最小相位系统的计算机仿真例子比较，可以显示出该方法的优越性。     

利用曲面曲率划分的高速数控加工进给速度修正

为保证数控加工中的切削效率和机床运动的平稳性,提出了基于曲面曲率划分的进给速度修正方法。以最大工作进给速度的变化比率为阈值,把零件表面的法曲率半径划分为不同的区域;在不同的曲率区域内,分别以恒定的刀触点速度对进给速度进行修正,修正后的进给速度随着零件表面曲率的变化而自适应变化;实例表明该方法具有合理性和有效性。     

基于状态反馈和参数调整稳定混沌系统的不稳定平衡点

针对OGY方法需要预先找到系统的一个可调参数的不足，基于状态反馈和参数调整，提出了稳定混沌系统不稳定平衡点的一种简单控制方法．根据线性控制理论选择控制参数，并研究了设计控制参数的准则．该方法不需系统的动力学知识，也不需要系统内部的任何控制参数．仿真结果验证了该方法的有效性．     

电阻测量方法的研究

详细分析了1kΩ～500GΩ电阻各量程的分辨率和测量电路输出信号范围，并以此为依据设计了实用的电路系统。同时给出具体的测量方法如下：首先判断电阻的范围，将放大器切换到合适的量程；放大后的电压信号经A／D转换送给单片机计算电阻值；根据各自量程的标准电阻值及其测量值之差进行动态校正。该方法消除了噪声对测量精度的影响。测试结果表明：在全量程范围内，最小测量误差为0.03％，最大测量误差为0.8％。     

Solaris下综合教务系统的管理和维护

对于Solaris下综合教务系统的管理和维护,本文从系统的优化调整,备份、恢复策略,系统安全保护措施等三个方面进行了探讨。     

循环流化床锅炉运行调节与控制

根据DG35/3.82—19型循环流化床锅炉运行的实践经验,对循环流化床锅炉在给煤量、风量及其分配、沸腾床温度、料层厚度等方面的控制与调节进行了总结。     

基于超音速火焰喷涂技术的冷喷涂技术实现与流场分析

在KY-HVO(A)F多功能超音速火焰喷涂的基础上通过改进喷枪的设计,在喷枪的扩张段加入水实现了冷喷涂技术.进行了冷喷涂过程中焰流流场分析,得到了不同水流量条件下喷枪中气流的速度与温度分布规律.为了定量分析,得到了喷枪出口中心处气流速度与温度随加水量的变化规律.结果表明:随着加水量的增加,粒子的速度与温度都在下降.在加水量较小时,焰流的速度与温度急剧下降.当加水量大于20L/h时,随着加水量的增加,焰流的温度和速度下降较慢.依据此流场分析结果在钢基体上成功制备了功能性涂层.     

空调循环水泵变流量控制多泵同时变频调节的重要意义

空调循环水系统中,多台水泵运行时多台同步变频调节和单台变频调节的比较     

Shear Stress in Smooth Rectangular Open-Channel Flows

The average bed and sidewall shear stresses in smooth rectangular open-channel flows are determined after solving the continuity and momentum equations. The analysis shows that the shear stresses are function of three components: (1) gravitational; (2) secondary flows; and (3) interfacial shear stress. An analytical solution in terms of series expansion is obtained for the case of constant eddy viscosity without secondary currents. In comparison with laboratory measurements, it slightly overestimates the average bed shear stress measurements but underestimates the average sidewall shear stress by 17% when the width–depth ratio becomes large. A second approximation is formulated after introducing two empirical correction factors. The second approximation agrees very well (R2>0.99 and average relative error less than 6%) with experimental measurements over a wide range of width–depth ratios.     

Adolescent Adjustment Before and After HIV-Related Parental Death.

The impact of HIV-related parental death on 414 adolescents was examined over a period of 6 years. The adjustment of bereaved adolescents was compared over 4 time periods relative to parental death and was also compared with the adjustment of nonbereaved adolescents. Bereaved adolescents had significantly more emotional distress, negative life events, and contact with the criminal justice system than nonbereaved youths; these behaviors did not remain significantly higher after parental death. Depressive symptoms and passive problem solving increased soon after parental death, as compared with nonbereaved adolescents. One year subsequent to parental death, depression and passive problem solving were similar to the levels of nonbereaved peers. Only sexual risk behaviors increased following parental death. These results suggest the importance of early family intervention soon after parental HIV diagnosis, prior to parental death, and sustained over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)