三角形接法三绕组单相电容电动机瞬态分析

对三角形接法的三绕组单相电容感应电动机的瞬态过程进行仿真分析．为了得到瞬态特性,建立了三角形(△)接法的三绕组单相电容感应电动机在αβ坐标系下的瞬态数学模型,编写计算机仿真程序,通过实例对三角形接法的三绕组单相电容感应电动机的瞬态过程进行仿真计算;用对称分量法分析了三绕组单相电容感应电动机最小不对称运行时需要满足的条件,并由此初步计算电容的数值,然后通过计算机仿真加以确定．对仿真结果进行分析．仿真结果表明：三角形接法三绕组单相电容运转电动机起动转矩较小,适合于对起动要求不高的风机泵类负载;对于起动要求较高或较大的恒转矩负载,可采用双值电容来实现．三角形接法三绕组单相电容电动机带负载的能力约为三相感应电动机在额定电压下对称运行时的0．7倍左右．     

MATLAB在感应电动机电气制动教学中的应用

为了得到三相感应电动机在电气制动运行过程中的动态特性，本文根据三相感应电动机在d—q静止坐标系下的数学模型，利用MATLAB软件中的动态传真工县SIMULINK，构造了三相感应电动机电气制动过程的仿真模型．通过实例对电源反接制动、能耗制动运行过程进行仿真计算，并对仿真结果用电机学原理进行解释，以帮助学生加深对理论的理解和认识．     

感应电动机转差-功率曲线的解析

中小型感应电动机的转差-功率曲线一般采用直接负载法通过负载实验进行测定,但对大型感应电动机在制造厂或现场进行负载实验都比较困难.利用感应电动机的较准确"Γ"型等效电路,提出了其转差-功率曲线的解析计算公式.在额定工况下,利用提出的解析公式得到的计算值与电机的设计值非常接近.另外应用MAT-LAB/Simulink仿真软件,可方便地画出感应电动机的工作特性曲线.     

基于电压源复数有限元的单相感应电动机性能计算

为提高单相感应电动机设计计算的准确性,并兼顾设计计算时间,将磁场方程和单相感应电动机的定转子电路方程相耦合,导出了电压源驱动的复数有限元模型,并将其与等效电路相结合,应用于单相感应电动机计算机辅助设计,采用电压源复数有限元法模拟空载实验和短路实验以准确计算等效电路参数,用等效电路计算感应电动机的性能.对实际电机进行性能计算和试验,计算结果与试验结果吻合较好.     

三相感应电动机单相短路故障的瞬态过程仿真

根据三相感应电动机在αβO坐标系下的数学模型，用MATLAB语言编写仿真程序。对三相感应电动机带恒转矩负载和通风机负载稳定运行时突然发生定子一相绕组对中点短路故障的运行过程进行仿真计算，并对仿真结果进行分析。     

三相异步电动机阻容制动时机械特性计算方法

本文在三相异步发电机运行理论基础上，利用等值电路对三相异步电动机阻容制动进行了详细的分析，导出了在任意转速下等值电路中频率Ｆ和激磁电抗Ｘｍ的计算公式，结合电路计算，提出了阻容制动时机械特性的计算方法。     

关于异步电动机采用阻容制动的几个问题

本文阐述了异步电动机阻容制动的基本原理。介绍了阻容制动时的电容,电阻配置方法     

Smith单相电容电动机电容器故障运行的建模

建立了Smith单相电动机电容器故障运行时在α - β - 0坐标系下的瞬态数学模型.此模型适用于任何接线方式的对称三绕组单相电容电动机电容器故障的瞬态分析,尤其便于计算机编程.通过实例进行仿真和试验,验证了该模型的正确性.研究表明,Smith单相电容电动机运行中电容器短路是一种较为严重的故障,有可能产生很大的冲击转矩,造成强烈的机械振动;电容器开路故障有可能使定子三相电流严重不平衡,致使某相绕组烧毁.     

异步电动机在非对称条件下的计算机仿真

本文利用异步电动机在相坐标系下的状态方程作为仿真模型，采用了适合于求解时变系数非线性状态方程的线性多步数值解法──修正阿达姆斯（Ａｄａｍｓ）预测校正法，建立了三相异步电动机的通用瞬态仿真程序，对异步电动机在两种典型的非对称条件下的瞬态过程进行了计算，较全面地，准确地获得了这些瞬态过程各机电量的变化，为研究异步电动机在非对称条件下的瞬变过程提供了一个有效工具。图８，参４。     

双转子环形绕组感应电动机设计

针对环形绕组感应电动机绕组材料利用率低导致电动机的效率和功率因数偏低的问题,提出了一种双转子环形绕组感应电动机(DRRWIM)的设计.首先分析了DRRWIM的结构、磁路和电路特点,根据分析结果提出一种电动机设计方法.通过该设计方法确定了电动机的基本尺寸,再利用三维有限元仿真分析方法对电动机的电磁性能进行仿真计算.最后根据得到的性能数据与同功率同极数的Y型传统感应电动机进行对比.结果表明,仿真计算验证了DRRWIM设计方法的准确性,电动机的对比证明DRRWIM更加高效节能.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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