基于GPRS的水文数据采集系统的设计

利用通用分组无线业务(GPRS)技术实现水文数据的采集是水文部门选择的通信手段之一.文章描述了基于GPRS技术的水文数据采集系统的组成,工作站与集中器以及采集器之间的数据传输原理,介绍了监控中心工作站应用软件的设计方法,同时,给出了工作站应用软件的主界面设计图.     

中板厂钢坯氧割渣在线清除系统的制作及应用

介绍了柳钢中板厂钢坯氧割渣的在线清除系统的组成及其生产性能。     

户式空调新风引入方式对室内热环境的影响

选择典型的装有分体空调的居室和办公室,对多种新风不同引入方式下室内的环境参数作了测试,比较并分析了新风引入方式对室内热环境的影响,提出了采用低位大新风量高风速引入方式室内温度场不平均度最小,即温度环境最好,并对所得结果进行了的理论分析。     

A novel autofocus algorithm based on maximum total variation criteria for SAR images

A novel autofocus algorithm for synthetic aperture radar (SAR) based on total variation is presented in this paper. The method, which starts with a complex phasedegraded SAR image, after the phase errors model is introduced into the range-compressed phase-history domain, carries out phase errors correction by changing the focus till the total variation of the azimuth profile is maximized. Compared with the minimum entropy autofocus algorithm, the autofocus algorithm has less computational complexity and is easier to implement. The simulation and the processing results of the measured data show the validity of the proposed method. Translated from Journal of Xidian University, 2006, 33(2): 167–172 [译自: 西安电子科技大学学报]     

异步化同步发电机无转速传感器控制

论述了异步化同步发电机有功功率和无功功率解耦控制原理,讨论了定子磁场的定位和转子位置的确定方法,以转子电流作为反馈量,构造了定子磁链观测器.借助于李亚普诺夫稳定理论,给出转子转速观测的递推模型.研制了DSP转子励磁控制装置,进行了异步化同步发电机无转速传感器的励磁控制试验研究.试验结果表明,转速观测器可以有效地确定转子转速,从而实现发电机的无转速传感器控制.     

Left-Handed Transmission Line Based on Resonant-Slot Coupled Cavity Chain

In this letter, a novel realization of left-handed transmission line is presented; the proposed structure is based on identical symmetrical resonant-slot coupled cavity chain. The dispersion characteristic of the resonant-slot coupled cavity chain is analyzed by means of field theory and finite element method (FEM) eigenmode simulation, and a left-handed passband is proved to exist. A backward wave behavior is demonstrated unambiguously from FEM driven modal simulation. The phase front is observed to be in the opposite direction with respect to the energy one for a finite nine-unit cell prototype     

消除高压噪声的继电器

大多数实验室和工业环境中都存在着多种全频带电气噪声源,它们来自于重型机器、仪表、电源和电视台.工程师要用很多设备和技术来对付这种噪声.这些技术包括采用正确的接地方式、屏蔽和双绞线、信号均化、差分输入电压放大器和滤波器.     

一种EMI表贴滤波器的测试

对于离频、表贴小尺寸滤波器的测试是比较复杂的.本文主要介绍了一种高频、表贴小尺寸滤波器的测试方法、测试线路和测试夹具制作所要考虑的各种因素.并采用老陵洞屏蔽技术较好的完成了一种高额、表贴小尺寸滤波器的测试,然后对所出现的问题进行了深入分析.     

一种观赏鱼养殖用高精度恒温控制系统的设计

本文介绍了一种基于集成电路的观赏鱼养殖用高精度恒温控制器,通过将目前普遍采用的温度-电压信号传输更换为温度-频率信号传输,实现高精密度恒温控制。