基于DDS改进BT-4型扫频仪

基于DDS技术,改造BT 4型扫频仪中的扫频信号发生器,使其具有高稳定度、高分辨率、高精度的特点。同时为了使扫频仪能够对被测电路的动态范围进行检测,使扫频仪得到更广泛的应用,运用了AGC控制技术,首先使电压稳定在10 V;然后通过控制D/A使输出电压按测试需要输出。硬件给出了具体电路参数,软件给出了相应软件流程,总结了其他波型产生的方法。     

频域吸收边界条件的构造理论

在频域中推导了适用于差分类数值方法的吸收边界条件的构造方法，并通过选取不同参数导出了几种现有的吸收边界条件。在计算了一般形式的吸收边界条件的反射系数之后，提出了一种简单实用的自适应吸收边界条件。     

水轮发电机定子浮动式双鸽尾筋调整工艺浅析

水轮发电机定子采用浮动式双鸽尾筋是当今设计上较为先进的结构,是防止定子铁心变形的重要措施之一,制造厂一般会提供安装调整的工艺措施,但此工艺措施更多的是检查的标准,对如何具体操作不够详细,安装调整完全依靠施工人员的经验进行。如何有针对性的分析调整工艺中的难点和易忽略点,提出更具指导性的调整工艺,成为了一个需研究的课题。     

一种可调节电流的电流型PWM直流转换器

介绍一种用于驱动发光二极管(LED)的可调节电流的电流型PWM直流转换器.该直流转换器由于接有一个外接电阻,可以通过调节外接电阻的大小来调节输出电流.输出电流调节范围在5～40mA之间.主要分析了电路的输出电流调节功能,和这种输出电流可变的电流型PWM直流转换器的电流和电压反馈环的反馈实现原理.并简要介绍了这种带电流调节功能的PWM直流转换器的工作原理,最后给出了电路在输出不同电流时使用HSPICE软件对反馈参考电压,PWM锁存器输出波形的仿真结果.     

Children's Physiological Indices of Empathy and Their Socioemotional Adjustment: Does Caregivers' Expressivity Matter?

Relations of heart rate and skin conductance reactions to mildly evocative empathy-inducing slides with socioemotional functioning were examined for 154 children (mean age = 9 years, 5 months). In addition, maternal expressivity was tested as a moderator of these relations. Parents and teachers rated children's socioemotional functioning, and a behavioral measure of children's regulation was obtained. Boys who exhibited higher skin conductance and higher heart rate to slides depicting negative emotions were better regulated, less emotionally intense, and better adjusted than their peers. Furthermore, boys' regulation and adjustment were positively related to such physiological responding to negative slides if maternal negative expressivity was relatively low or moderate, but not high. Fewer findings were obtained for girls or for positive slides. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

浅谈热水采暖系统运行调整方法

介绍了热水采暖系统运行及调整的注意事项，分析了立支管阀门、集气罐的作用，提出了使热水采暖系统的调节和集排气操作达到理想程度的有效措施，以实现良好的供暖效果。     

Siblings' differential experiences of marital conflict and differences in psychological adjustment.

The present study examined whether siblings experience marital conflict differently and whether such differences, if present, were associated with differences in their adjustment. Self-report data about marital conflict, children's depressed mood, behavioral conduct, and externalizing problems were obtained from 122 sibling pairs (mean ages = 10 and 12 years) and their parents. Results indicated that siblings were significantly different in exposure to and appraisals of marital conflict. Differences in siblings' exposure to marital conflict were significantly correlated with differences in their depressed mood, behavioral conduct, and externalizing problems. Differences in siblings' feelings of self-blame for marital conflict were significantly correlated with differences in their depressed mood and behavioral conduct. Children who experienced more marital conflict than their siblings had more adjustment problems than their siblings. These results highlight the importance of studying siblings' unique experiences of marital conflict to better understand its impact on children's adjustment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

矿用交换机用户线接口电路

介绍了一种由新型集成芯片组成的电话用户线接口电路，由用户线功能块DTLM630和可编程单片全双工增量调制解调器CMX639等组成。由于芯片的高度集成化，从而使电路结构简单，使用可靠，是一种新型实用的用户线接口电路。     

一种抑制SDH网中指针调整抖动的平滑相位泄漏技术

指针调整会在ＳＤＨ网中引入非常大的低频抖动。通常，在解同步器中需要采用指针泄漏技术来抑制这种抖动以使设备满足ＩＴＵ－Ｔ建议Ｇ．７８３的要求。本文给出了一种新颖的抑制指针调整抖动的方法，这种方法通过一个数字锁相环对指针抖动进行平滑并将平滑相位调相到一个参考信号上，从而避免了１比特或１／Ｎ比特泄中存在的较大的相位量化阶跃。这种方法对指针抖动的泄漏可以近似为一个平滑的过程。对一个ＡＵ－４／Ｅ４实验系统的     

先进控制在环管法聚丙烯装置中的应用

以九江石油化工总厂70kt/a聚丙烯装置产率控制为例,介绍先进过程控制系统在石油化工装置上的应用情况。