Performance Characteristics of Alpha-Particle Corona-Streamer Counter

Alpha-particle wire-plate corona counters in air can be operated either in the spark or in the corona-streamer modes. The streamer mode is preferred over the spark mode since it has the advantages of low dead time and the absence of electrode corrosion by sparking. An analysis of the alpha-particle corona-streamer counter is described. The alpha-particle triggered corona pulse characteristics (e.g., pulse shape, amplitude, repetition rate, etc.) are calculated. Not only the pulse characteristics but also the inception voltages of the corona-mode regime are determined. For each wire diameter, a transition gap length between corona and spark modes exists, which is termed ``critical gap length.' The counting rate characteristics have been obtained for wire diameters 0.05-0.1 mm. All the theoretical findings are confirmed by experiment.     

同步任意值计数器的设计

多值计数器的设计与二值计数器的设计不相同，因为一般多值触发器本身并不具有多值计数功能，所以多值计数器的设计首先要解决如何实现一位多值计数器的计数问题；另外要解决如何实现多位计数器的低位向高位的进位问题．此外，还介绍了几种具有代表性的四值计数器的设计，其方法可适用于任意值计数器的设计．     

异步任意值计数器的设计

多值计数器是构成多值数字系统的重要功能部件、多值计数器的设计与二值计数器的设计不同，因为一般多值触发器本身并不具有多值计数功能。所以多值计数器的设计首先必须要解决如何实现一位多值计数器的计数问题；另外还要解决如何实现多位计数器的低位向高位的进位问题。除了讨论如何解决喧两个问题外，还介绍了几种具有代表性的四值计数器的设计，其方法可适用于任意值计数器的设计。     

伪随机计数器的设计原理

传统线性加减计数器的进位结构制约了计数器硬件在高速度下的应用,将通讯系统中的伪随机序列的原理应用在计数中便可达到高速计数的目的.本文通过详细介绍4位伪随机计数器来说明伪随机计数器的原理.进而寻求实现任意位伪随机计数器的公式,即本原多项式.最后介绍了一些经过FPGA仿真的实验数据,数据对比了加减计数器和伪随机计数器在运算速度上的显著差距.     

VXIbus四通道计数器模块仪器设计与分析

文中以ＶＸＩｂｕｓＣ尺寸四通道通用计数器模块的硬件和软件的设计为例，介绍了ＶＸＩｂｕｓ模块仪器的设计方法。并对一些相关技术进行了分析。     

通用计数器的VXIplug＆play软面板设计

本文介绍ＶＸＩｐｌｕｇ＆ｐｌａｙ软面板设计的要求的设计原则，并利用Ｖｉｓｕａｌ Ｂａｓｉｃ在Ｗｉｎｄｏｗｓ软件平台上开发了符合ＶＸＩｐｌｕｇ＆ｐｌａｙ规范的通用计数器软面板。     

基于FPGA的多通道时间间隔计数器设计

文章介绍了一种基于数字内插技术的高精度、多通道时间间隔计数器设计.此计数器采用了"差分延迟链"结构的数字内插器,减少了量化误差.此计数器设计在Xilinx ISE 7.1i环境下完成程序编制,并以Spartan 3 XC3S1500 FPGA芯片为载体,上述的所有功能单元集成于其上,仅需少量外围部件,并与处理单元相结合即可实现高精度的时间间隔测量.     

序列生成式全状态移位计数器研究与设计

由于传统移位计数器状态利用不足，本文提出全状态移位计数器。通过分析移位计数器状态转换特点，得到全状态移位计数器状态转换规律。根据这种转换规律，总结了反馈序列的构成，给出了反馈序列算法以及从反馈序列求反馈函数的方法，从而系统地介绍了全状态移位计数器的设计。     

The Performance of a Single-Phase Current-Fed Inverter with Counter EMF?Inductive Load

Current-fed inverters that have series diodes to trap the charge on a commutating capacitor can supply ac loads of any power factor. A single-phase circuit with counter emf-inductance load, such as a motor, has been analyzed by digital computer simulation, valid for all modes of operation. The magnitude and phase of the ac load current are graphically related to the direct current and thyristor firing angle with respect to the counter emf. The ratio of the operating frequency to the natural ringing frequency of the commutating capacitance and the load inductance is a parameter of the circuit that significantly affects its behavior. Problems associated with high-frequency operation in a drive system are discussed.     

Power Electronics Design Laboratory Exercise for Final-Year M.Sc. Students

This paper presents experiences and results from a project task in power electronics for students at Chalmers University of Technology, GÖteborg, Sweden, based on a flyback test board. The board is used in the course Power Electronic Devices and Applications. In the project task, the students design snubber circuits, improve the control of the output voltage, improve the gate drive of the main MOSFET transistor and study the influence of stray inductance. The project goals (the circuit improvements) are given, but the procedure for solving the problems and obtaining the results is not specified. Instead the students have to make their own specification in order to reach the goals. “Tools” that are given to the students are the hardware, measurement equipment, an example of the circuit in the circuit simulation software PSpice, and lastly lectures covering the material needed in order to attain the project goals. The project design builds on the ideas from the CDIO (Conceive, Design, Implement, Operate) initiative, where students are encouraged to consider the complete process structure. The result found was a substantial engagement by the students, who had both positive and negative reactions. The negative reactions were mainly that the project specification was too vague, in other words in the (C=Conceive)-phase of the CDIO structure. Further, the teachers observed increased learning, which also was noticeable for the students performing their M.Sc. thesis within the power electronics design area. Finally, it was found that a final written exam is definitely still needed to assess students adequately in the course.      

超大型自然通风逆流式冷却塔的配水设计

通过对彭城电厂12000m²自然通风逆流式冷却塔的配水设计分析,指出了我国引进比利时哈蒙设计技术的中央竖井配水方式有一定的适用范围,采用XPH型喷头淋水面积不大于11000m²,而采用反射型喷头最大淋水面积为40000m²,同时提出了超大型冷却塔的双竖井日字型配水方案,水力计算结果表明,该方案可提高冷却塔配水的均匀性。     

交流伺服系统的电气设计及动态性能分析

介绍了一种高性能三维雕刻机的电气接线设计,对该伺服系统进行了动态性能的测试与分析,实现了伺服系统的在线调试,给出了系统的响应曲线和重要技术参数。     

WCA无线通讯分析仪可满足3G测试性能分析的需求

本文主要对WCA无线通讯分析仪3G测试性能进行分析，同时与其他相近测试仪器进行了比较，对WCA的在无线通讯研发中的优缺点也进行了分析，可以作为3G无线通讯测试的工作参考。     

M701F型燃气轮机性能分析

据文献[1]关于M701F型燃气轮机性能信息,利用ASPEN软件建立了较详细的系统及部件热力计算模型。首先对燃料流量和燃烧空气流量与压气机、透平和燃烧室的主要性能进行计算,然后将数据输入ASPEN软件进行模拟,得到较全面的燃气轮机性能参数。并在此基础上,研究燃气轮机随大气温度变化时的变工况性能。     

嵌入式主板性能分析及设计

文中对嵌入式主板设计提出数据流模型分析的方法,利用该方法能判断在PortX上是否能加业务卡,及所加的业务卡的限度.在实际开发测试中证实分析的正确性,并为该类主板设计提供一定的参考估算方法.     

2M有损切换装置的主要性能测试

为进一步提高电力通信系统运行的稳定性,最大程度减小因通信检修或故障引起的对电网保护、安控等重要生产业务的影响,需要在承载直流保护、安控等业务的一级骨干电力传输线路上配装2M有损切换装置。文章介绍了有损切换装置（LSD）的工作原理,给出了实验室条件下该装置在电力通信应用中主要性能的测试结果,最后对该装置在实际应用中存在的问题进行了说明。     

并网独立双模式控制高性能逆变器设计与实现

本文设计并实现了一种小型的用于分布式发电系统的功率调节系统。高性能，高可靠性，高功率密度是功率变换装置的基本要求。传统的并网逆变器输出采用工频变压器，体积重量大，成本高。本文采用高频隔离的逆变器，消除了输出端的工频变压器。传统的桥式逆变电路存在桥臂直通问题，本文将双降压式逆变器用于并网发电场合，提高了可靠性，提高了效率。半周期调制方式的采用减小了器件的开关损耗，以及功率场效应管的导通损耗。以往的文献对并网逆变器的分析侧重于单独工作模式或者并网模式，较少涉及到独立工作和并网工作切换过程的分析。本文分析了双模式运行的逆变器的切换过程。采用TMS320F240DSP芯片实现数字锁相同步，实现并网和独立控制的逻辑和基准切换。在此基础上实现了一个500VA的实验样机证明了方案的可行性。     

Design and Performance of a High-Efficiency Commercial

A gas-fired commercial water heater has been developed which achieves a steady-state efficiency of over 95 percent and can obtain overall service efficiencies above 90 percent in many applications. These high levels of efficiency are obtained by operating in the condensing mode over a substantial portion of the duty cycle. The use of a power burner and a coil-type heat exchanger results in a compact configuration which produces both high efficiency and low emissions. The design, operating principles, and performance characteristics of the water heater are described.     

伺服设计的性能极限

线性控制器设计的一个重要方面是要了解这个设计是否达到了性能极限，通常，达到性能极限依赖于有效的设计方法，本文揭示出μ综合能够系统地使服系统的干扰抑制设计达到性能极限，并指出性能极限是由系统的带宽决策的，基于性能极限的结果，文中给出了伺服设计权函数选以的原则。     

带微机的通用电子计数器及误差分析

本文介绍了具有多种测量功能的带微机的通用电子计数器的基本原理和电路特点,对采用多周期同步法测量频率、周期、比率的误差进行了详细的分析,并给出了误差计算公式。