静态工作点稳定电路频率特性的虚拟测试研究

利用Multisim12.0仿真软件对静态工作点稳定电路的频率特性进行了测试研究,观察了幅频特性曲线和相频特性曲线的变化规律;采用"交流分析"或波特仪等方法,测试了耦合电容、旁路电容和静态偏置电阻等电路参数改变引起的中频电压增益、上限截止频率和下限截止频率的变化。发现虚拟测试的结果与理论分析计算结果基本一致。将Multisim12.0仿真软件合理地用于电路实验教学中,有助于提升学生的实践动手能力。     

基于MATLAB的离散系统分析

利用MATLAB分析离散系统的时域响应和频域响应,对建立的系统数学模型进行模拟仿真,进而分析离散系统的因果性、稳定性、幅频特性和相频特性。仿真结果能直观清晰的反映离散系统特性．为研究数字通信系统物理实现特性和评价数字通信质量提供了前提基础。     

交流电路频率特性的集中表示方法

一般讨论交流电路的频率特性时,幅频特性和相频特性分置在不同的坐标体系中。尽管这种方法比较详尽地说明了交流电路的频率特性,但对初期了解交流电路频率特性的人来讲,往往不容易把幅频特性和相频特性统一起来,造成理解上的片面或困难。文章在总结传统解释方法后,给出了一种把幅频特性和相频特性统一在同一坐标体系内的解释方法。这种解释方法把幅度、相位、频率集合在同一坐标平面里,集中反映交流电路的频率特性,使人们更容易理解交流电路的频率特性。     

基于零中频解调的高精度频率特性测试仪设计

通过对比验证几种常用的中低频频率特性测试方法,提出了一种基于零中频正交解调原理的中低频频率特性测试仪的设计方法。将被测网络的输出信号分别与两路正交输入信号相乘,并用低通滤波器将其交流成分滤除,其结果中的直流分量便包含了被测网络的幅频特性和相频特性信息。整个系统仅采用模拟乘法器对信号进行混频,无源低通滤波器对信号进行解调,简化了电路结构。采用高精度AD进行模数转换,提高了测试精度。     

压控电压源二阶低通有源滤波电路设计与仿真

利用Multisim10.1软件对压控电压源二阶低通滤波器进行仿真分析,通过选择不同信号源观察输入、输出波形的相位关系和幅值关系,比较输出、输入波形幅值比是否等于通带电压放大倍数;调节负反馈电阻大小,观察品质因素变化对滤波器幅频特性和相频特性的影响,得到的仿真的结果与实际理论分析基本一致。仿真结果表明,将Multisim10.1合理地引入到模拟电子线路实验教学中,能将一些高深、抽象的电子电路的理论教学变得具体和生动,有利于学生对电路的认知,提高电子线路理论课的教学效果和教学质量。     

基于FPGA和MSP430的频率特性测试仪

以FPGA和MSP430F6638为控制核心,主要包含信号源、被测网络、检波及显示部分。其中,测试信号源基于DDS原理,可以实现0.1~150 k Hz的扫频,最小步进10 Hz,稳定度优于10-4,测量精度1%。并设计制作了中心频率5 k Hz,带宽±50 Hz的阻容双T网络。检波部分采用高性能芯片AD637测量双T网络输出信号的有效值,通过单片机计算峰值;并将输出、输入信号分别放大整形得到稳定的方波输入FPGA计算相差,从而绘制幅频特性曲线和相频特性曲线。可以通过键盘设置步进,切换幅频特性曲线、相频特性曲线的显示界面,以及其他参数的显示和查看。整个系统是单片机和FPGA的有机结合、协同控制下,工作稳定,测量精度高,人机交互灵活。     

基于声卡的虚拟数字存储示波器及其在电学实验中的应用

利用虚拟仪器开发工具软件LabVIEW及其数字声音记录节点,研制出基于声卡的虚拟双踪存储示波器,其功能和界面都与真实示波器相同.以RLC串联电路的幅频特性和相频特性实验为例,说明其应用于电学部分物理实验教学,得到与传统实验仪器一致的实验结果,完全可以代替真实示波器进行教学实验.     

RC网络的转移函数的频率特性问题

本文针对《电路分析》中几种常见的RC网络,以相量法的形式详尽分析其网络的转移函数的幅频特性及相频特性,经过对比、综合以明了各种RC网络的具体应用。     

测量有源滤波电路频率响应的虚拟扫频仪设计

为了满足有源滤波电路等模拟电子电路频率响应测量的需要,克服传统测试方法中仪器比较多,步骤较复杂且容易产生较大误差的缺陷,介绍了一种基于LabVIEW的虚拟扫频仪设计方法。简述了该扫频仪的整体设计方案和测量原理,详述了扫频仪主要的软件设计模块。实验结果表明,该扫频仪能直观测试电路的频率特性及绘制出相应的幅频特性和相频特性曲线,能较好的满足有源滤波电路频率响应的测量。     

RC网络的转移函数的频率特性问题

本文针对《电路分析》中几种常见的ＲＣ网络,以相量法的形式详尽分析共网络的转移函数的幅频特性及相频特性,经过对比,综合以明了各种ＲＣ网络的具体应用。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

胡主席在印度,我却在中国

Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer.     

STORIES

正A One day a pig went to the stable(马棚)to see his good friend,an oldhorse,and was going to stay there forthenight.Night came and it was time forsleep.The pig went into the straw heap(稻草堆)and lay comfortably.A longtime passed,but the horse was stillstanding there and did not move.Thepig asked the horse why he did not go tosleep."Standing like this is the begin-ning ofsleeping,"answered the horse.     

巧妙引语(英文)

正1.Any fool can count the seeds in an apple.Only God can count all the apples in one seed.2.Happy families are all alike;every unhappy family is unhappy in its own way.3.Memories are the key not to the past,but to the future.4.Sometimes in the dark you see what you want to see.5.There is a great difference between     

Information for Authors

正Scope and Policy The Journal of Chongqing University-English Edition(JCQU-E)is a peerreviewed journal publishing research articles in multiple disciplines of science and technology,covering civil and environmental engineering,chemical engineering,biotechnology,mechanical and electrical engineering,computer and data processing,mining,metallurgy,materials science,and interdisciplines thereof.