辐射干扰下通信接收系统的阻塞性能研究

本文主要在通信接收系统抗阻塞干扰性能方面做分析研究。根据阻塞干扰的原理,分析系统线性度指标,通过建立通信接收系统行为级仿真模型实现阻塞干扰对通信系统的影响,并提出了若干避免和解决阻塞干扰的方法措施。该研究对辐射干扰下通信接收系统的设计和性能分析具有很好的理论指导意义。     

大功率电磁加热系统电磁兼容性分析设计技术探讨

文章对大功率电磁加热系统的电磁兼容性进行了分析,针对系统中的主要电磁干扰源,从传导干扰以及辐射干扰的角度对这些干扰的产生机理进行了分析。从电路布局设计、屏蔽技术两个方面提出了一系列抑制干扰的方法与原则。可为大功率电磁加热系统的设计提供参考。     

显控台电场辐射发射超标诊断及整改方法

显控台是很多舰船以及潜艇上的火控系统的重要组成部分。电场辐射发射(RE102)是考核显控台对外界电场辐射干扰强度,是显控台非常重要的电磁兼容测试项目。为了保障显控台的电磁兼容性,深入研究电场辐射发射整改技术对保障显控台的电磁兼容性的意义非常重大。     

ECG中50Hz干扰的抑制及其性能

分析了ＥＣＧ（心电图）和市电工频５０Ｈｚ干扰的特点及ＥＣＧ记录的高要求,提出采用结构简单的两个权的自适应凹口滤波器的自适应干扰对消器（ＡＮＦ）抑制ＥＣＧ中的５０Ｈｚ干扰。通过对ＬＭＳ算法时的传输函数和计算机模拟结果,从频域和时域分析了抑制性能。     

COD_(Cr)测定中排除氯离子干扰的进一步探讨

废水中化学需氧量的测定采用重铬酸钾法［１］,大多数情况下都存在Ｃｌ－干扰,其排除方法用ＨｇＳＯ４掩蔽,通过实验探讨不用剧毒药品ＨｇＳＯ４掩蔽Ｃｌ－的干扰,而用ＣＯＤＣｒ总量减去Ｃｌ－的量。实验结果表明：当测定化学需氧量较低而Ｃｌ－含量高的水样时,即使采用掩蔽Ｃｌ－也会产生较大的误差,而用测定值减去０．２２６［Ｃｌ－］之值更接近真值。     

消除氯离子对CODcr快速仪法干扰的实验

氯离子浓度高于５００ｍｇ／Ｌ时,对ＣＯＤｃｒ的测定呈混浊干扰,通过加入ＨｇＳＯ４络合氯离子,可消除氯离子含量达２０００ｍｇ／Ｌ的干扰,过量的ＨｇＳＯ４对ＣＯＤｃｒ结果无影响。     

重金属离子对络合法（EDTA）测定Ca^2＋的干扰及其消除

用ＥＤＴＡ法测定Ｃａ＾２＋时，对Ｆｅ＾３＋，Ｃｕ＾２＋，Ｐｂ＾２＋，Ｍｎ＾２＋的干扰进行了试验，分别得出了最小干扰浓度，不同的干扰离子和浓度。采用不同的方法消除，效果良好。     

判决反馈用于CDMA中抑制单频干扰的性能分析

提出一种三值滤波器输入和权值修正中均采用判决值的非线性判决反馈干扰抑制器，用于抑制ＣＡＤＭ中的单频干扰。     

移动通信CDMA中的单频干扰抑制

应用自适应干扰对消技术，彩 自适应线性预测器抑制ＣＤＭＡ中的单频干扰。根据常规的固定步长ＬＭＳ（ＦＳＳ）算法的缺点，采用了可变步长ＬＭＳ（ＶＳＳ）算法。分析了ＶＳＳ算法的收敛性能，给出了ＦＳＳ和ＶＳＳ算法抑制ＣＤＭＡ中单频干扰的计算机模拟和分析结果。     

适用于生物学研究的实验室水系统设计

本文介绍的是一种实验室再循环小型水源系统,它能对大多数物理变化进行分度控制。它是专门为研究栖居于急流环境中的淡水水底大型无脊椎生物而设计的。这种系统已被成功地用于鉴定Simuliidae幼虫所喜爱的流速。这种系统还可用于研究由于毒物或人为水流和温度的改变对栖居于急流中的生物种类的干扰作用。     

生活垃圾逆推式炉排炉自动燃烧控制系统设计

生活垃圾焚烧状态因垃圾本身性质不稳定而容易发生波动。自动燃烧控制系统具有焚烧状态稳定、二次污染减少等优点。针对逆推式炉排炉自动燃烧控制系统,阐述了控制目标和控制逻辑,详细描述了锅炉蒸发量回路设定、给料器和炉排运行控制及助燃空气控制等系统组成,说明了关键参数的设定和控制,并对系统的前馈控制特征做了描述和分析。     

Quantized control settings based tuning of a heaving wave energy converter in irregular seas

The increasing awareness of environmental issues attracts more attention on environmentally friendly energy sources. This leads to increasing research on effective use of renewable energy sources. Among them, wave energy offers a high potential. The wave energy converter systems used for transforming the wave energy into electrical energy have been a main research topic for decades. However, only a few of these systems has been successfully implemented. There seems to be some technical problems one of which is on their control applications. It has been reported that by means of appropriate control implementation, the performance of the wave energy converter system could be improved considerably. In literature, many different control techniques are reported. They appear to be weak due to implementation related restrictions. The present study proposes a novel control technique that is far more practical based on quantization of control settings. Various quantization levels and their effect on system power capture performance are studied. The technique assumes use of realistic off-the-shelf components with realistic features. The proposed method utilizes time-series-analysis technique with online parameter estimation feature. This new method does not require any knowledge of previous or future states of any of the system or sea state parameters, but only the currently available and measurable ones. The approach of the new control technique sets it apart from most of the previously reported ones. Therefore, the proposed technique is not only very much practical but also very much useful in improvement of the system power performance relative to passive techniques.     

光脉动混凝投药技术的控制模式及其优化

光脉动检测技术以透过流动悬浮液的光强度的脉动状态反应絮凝颗粒的尺寸与生长情况,其检测值R值可以作为控制参数来控制混凝剂的自动投加。目前,光脉动混凝投药控制系统已经具有单回路、串级、前馈反馈、前馈串级等多种控制模式,使该项技术具有     

火电厂电除尘器电控系统的节能改造

电除尘器是火力发电厂的高能耗设备,从细节入手,挖掘电除尘器节能潜力,利用原有设备进行改造,采用简易脉冲供电方式和临界反电晕供电方式可以提高电除尘器电能的利用率,大幅度地降低电除尘器的能耗,实现节能。通过对电除尘器电控系统改造实例的前后电场参数进行比较,说明这种改造方法是可行的,实现了经济、节能与环保三者的兼顾与统一。     

“多规合一”开展现状及成效分析

在研究"多规合一"发展演变历程的基础上,深入剖析"多规合一"的内涵:"多规合一"是各类规划的统筹,是系统的空间管理,是简政放权的手段。从市级、省级两个层面,论述了广州、厦门、海南等试点城市"多规合一"开展的现状,比较各试点城市牵头部门、规划体系、发展步骤等发展模式的不同,总结"多规合一"开展以来在解决规划打架、盘活土地资源、缩短审批时间、实现资源共享、加强生态管控等方面取得的成效,梳理出开展过程中遇到的难点和问题,并展望下一步工作。     

Improving the dynamic response of frequency and power in a wind integrated power system by optimal design of compensated superconducting magnetic energy storage

The frequency deviation and power fluctuation need to be controlled in a wind-integrated power system (WIPS) for keeping the balance between system power generation and demand, which support the quality and stability of overall power system. The present paper addresses this problem while concerning the integration of intermittent wind power and load disturbance into the WIPS. With this intent, it proposes the compensated superconducting magnetic energy storage (CSMES) system with proportional integral derivative (PID) controller for improving the frequency and power deviation profile. A novel swarm intelligence-based artificial bee colony (ABC) algorithm is used for optimal design of PID-CSMES system. Robustness of the proposed ABC-based PID-CSMES control strategy is tested in WIPS under various disturbance patterns of load and wind power. To demonstrate the improved dynamic response, their simulation results are compared with particle swarm optimization-based PID-CSMES, PID with SMES, and only PID controller technique. The performance indices and transient response characteristics of frequency and power deviation are used to evaluate and compare the accuracy and efficiency of each controller. Stability of various system configurations is analyzed using eigenvalue location. Comparing the results of different controller in WIPS indicates a substantial improvement in the dynamic response of system frequency and power deviations by utilizing the proposed control strategy.     

An Investigation of Flashing-Driven Natural Circulation

Natural circulation driven boiling systems are extensively used for passive heat removal, such as in nuclear power plants. The flashing phenomenon and the associated flow instabilities in a natural circulation loop are reported here. An experimental facility is constructed with a heater, an adiabatic riser, a condenser and an adiabatic down comer to study the instability regions. The experimental geometry is modeled using RELAP5. At high power (i.e., at 6 kW) flashing instability is observed when the inlet sub cooling is within the range of 7° C to 12° C. It is also found that the presence of an inlet restriction does not help to suppress the flashing induced flow oscillation. A good comparison between the experimental and numerical results is observed and this loop can be used for validation exercises of commercial codes.     

Off-design performance analysis of a transcritical CO2 Rankine cycle with LNG as cold source

The transcritical CO₂ Rankine cycle with liquefied natural gas (LNG) as cold source is a promising power system to utilize mid- and low-temperature heat source. Most previous works focused on thermodynamic and thermoeconomic analysis or optimization for the system. In this article, an off-design performance analysis for the system is conducted. An off-design mathematical model for the system is established to examine the variation of system performance with the variations of heat source mass flow rate and temperature. A modified sliding pressure regulation control strategy, which regulates turbine inlet pressure to keep the temperature difference between heat source temperature and turbine inlet temperature constant, is applied to control the system when off-design conditions happen. The results show that when the mass flow rate or the temperature of heat source is less or lower than that of design condition, both the net power output of system and the system exergy efficiency decrease, whereas when they are more or higher than the values of design condition, the net power output of system increases but the system exergy efficiency still decreases. In addition, both CO₂ turbine and NG turbine could almost keep the designed efficiency values under the applied control strategy.     

VTB-Based Design of a Standalone Photovoltaic Power System

Abstract

Design and prototyping of a standalone photovoltaic power generation system using the Virtual Test Bed software environment is presented. The design includes establishing physics-based models for components, prototyping system architectures, implementing control algorithms, testing and evaluating the system performance using the actual weather data at a particular geographical location. The dynamic performance of the photovoltaic power system and its components are revealed in great details through the system level simulation. This knowledge is used for verification and improvements of the system design in order to achieve the best system power capability, efficiency and size.     

Development of a PEMFC-based heat and power cogeneration system

Hydrogen-fed proton exchange membrane fuel cell (PEMFC) has to overcome high installation and operation cost before being adopted as a distributed power candidate. Cogeneration of power and heat is a good approach to increase hydrogen energy utilization rate. A PEMFC-based power and heat cogeneration system is proposed and established in the current study to investigate system’s technological and economical feasibility. This cogeneration of heat and power (CHP) system composes of a 2.5-kW fuel cell stack, hydrogen supply system, air supply system, water and heat management system, and heat recovery system. The control strategies to automate the system operation are realized by a programmable automation controller (PAC) system. Detailed measurement of the system is also constructed along with a web-based human–machine interface (HMI) platform to facilitate experiments and demonstration. Preliminary testing of the CHP system shows good performance of heat and power outputs. System’s electrical power conversion efficiency and thermal efficiency of the CHP system are measured at 38% and 35%, respectively. System combined efficiency therefore reached about 73%.