传输导线等效电阻与频率的关系研究

依据趋肤效应对导线横截面上电流密度分布影响的公式，推导出了传输导线等效电阻随频率变化的关系式，并将等效电阻随频率变化的计算值与文献中已有的实验测试值进行了比较，发现频率越大，误差越大．在考虑了导线自身电感值的条件下进行了实验测试，其结果与理论计算值基本一致，证实了在频率较高的情况下，传输导线的自感对实验结果的影响不能忽略。     

传输导线等效电阻与频率的关系研究

依据趋肤效应对导线横截面上电流密度分布影响的公式,推导出了传输导线等效电阻随频率变化的关系式,并将等效电阻随频率变化的计算值与文献中[1]已有的实验测试值进行了比较,发现频率越大,误差越大.在考虑了导线自身电感值的条件下进行了实验测试,其结果与理论计算值基本一致,证实了在频率较高的情况下,传输导线的自感对实验结果的影响不能忽略.     

提高SOA驱动电路开关速度到纳秒级的方法

建立了半导体光放大器SOA与夹持架的等效模型,将SOA、夹持夹、导线构成的系统看作一个由电阻、电感、电容和理想二极管D并联后3部分串联的一个电路,并对此模型进行了理论分析和计算机仿真.文中给出了基于此模型进行的实验结果.结果表明:通过调整电阻和电容的值,可以有效地将驱动电路的开关速度提高到纳秒级.     

开尔文电桥测低电阻的原理讨论

本文从考虑了导线电阻及接触电阻后的双臂电桥等效原理图出发，分析讨论了开尔文电桥如何消除导线电阻及接触电阻对低电阻测量结果的影响，并以此为基础，简单讨论了测量误差的主要来源及相应措施。     

开尔文电桥测低电阻的原理讨论

本文从考虑了导线电阻及接触电阻后的双臂电桥等效原理图出发，分析了讨论了开尔文电桥如何消除导线电阻及接触电阻对低是阻测量结果的影响，并以此为基础，简单讨论了测量的主要来源及相应措施。     

微机械平面螺旋电感的Q值分析与结构优化

为优化微机械平面螺旋电感 ,提出了一种计算品质因数 (Q值 )的方法。通过系统分析影响平面螺旋电感 Q值的主要因素 ,获得硅微机械电感的简化模型 ,在此基础上采用电磁分析法讨论了射频条件下高频电磁场效应对电感寄生电阻的影响 ,从而得到了计算平面螺旋电感 Q值的方法。利用此方法对几何参数不同的几种线圈进行分析 ,获得了具有较高 Q值电感的优化结构。在 2 GHz的工作频率下 ,优化的平面螺旋结构线圈导线宽度和厚度分别为 10μm和5μm     

接线电阻对实验结果的影响

电阻是电学中很重要的物理量,而在电学实验中,对结果的影响,导线电阻起着至关重要的作用。电磁测量是测量技术的一个重要组成部分,它包括了对电流、电压、电阻、电感、及其它各种电磁量的测量。实验是修正错误的依据和发展起点。文中针对电学实验中导线连接对实验结果产生较大误差,列举三个典型电路进行讨论和分析,并提出解决方案。     

一种鲁棒脉宽调制的无差拍并网控制方法

在并网逆变器的无差拍电流控制中,逆变器输出滤波电感值变化和滞后一拍延时会直接影响并网电流的畸变率、系统稳定性与动态响应速度.对此,本文提出了一种鲁棒脉宽调制的无差拍并网控制方法,减小了因滤波电感值变化对并网电流造成的畸变,有效地解决了滞后一拍控制引入的延时问题,降低了系统闭环传递函数的特征根方程阶次,提高了系统的稳定性及动态响应速度.分析了滤波电感偏差系数对系统性能的影响,得到系统临界稳定的滤波电感偏差系数随着滤波电感的寄生电阻和线路等效电阻的增大而增大,随着采样频率的增大而减小的结论.综合考虑系统的稳定性与动态响应速度,给出了关键控制参数的优化选取范围.仿真和实验结果验证了所提方法的有效性.     

滤波器的计算机建模分析与仿真

讨论了电子电路计算机仿真分析的方法，对滤波器进行了数学建模与计算机仿真计算，分析了在电路参数不变的情况下，滤波器对其频率的响应，以及滤波器中电阻，电容对滤波效果的影响。计算结果表明：随着频率的升高，滤波输出信号幅度逐渐和，呈现出较理想的低通滤波器特性；RL的增大使输出波形的峰值增大，C，R值越大，滤波器的滤波效果越好。仿真结果与理论计算值电压转移函数Ho(S)相符。     

低频楼梯压电发电装置的数学模型和实验

 为收集和利用密集人群对楼梯的踩踏能量,设计了一种基于低频的新型楼梯压电发电装置,基于RLC 等效内阻建立了该装置的发电电路和数学模型;利用搭建的振动实验平台,对等效电路和数学模型进行实验验证。结果表明,在低频条件下,激励位移越大,频率越小,该压电发电装置输出的电能越大;压电发电单元的实验输出电压为电路中等效电阻Z₂的电压,利用数学模型计算得到的理想电压源电压是实验空载电压的2.64~2.88 倍;通过对实验数据的分析计算,得到了与理论计算电压变化规律相一致的实验电压源电压,两者最大误差为7.1%,验证了该压电发电单元等效发电电路和数学模型的正确性。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the