水电站动态发电模型

为了揭示水电站功率输出与发电流量及水头损失间的动态变化过程,将水库水体分成长方形水体s1、梯形水体tr、长方形水体s2及三角形水体t等4级,运用牛顿运动定律,分析了压力引水管水体受力情况,推导压力引水管水体动态运动方程,综合考虑压力引水管水头损失及水锤压力的影响,建立了水电站动态发电模型.仿真结果表明,模型动态揭示了水电站在发电过程中的水位、流量、水力损失水头等参数间的相互影响关系及其对机组功率输出的影响,揭示了水电站最优发电功率输出与水头变化的动态变化过程,为未来水电站设计更优化的控制调度系统提供新的研究思路.     

引水式电站并列运行机组的MATLAB仿真模型

为了研究高水头引水式水电站机组之间的水力干扰问题，采用MATLAB下的SIMULINK作为仿真工具，建立共用有压引水管道、调压井、压力主管的两台高水头引水式水轮机调节系统小波动时的仿真模型，对于大波动时水轮机特性的非线性问题，给出了水轮机传递系数仿真模型的建立方法，结合两方面模型，建立了整个调节系统在大波动时的仿真模型，并引入实际电站的参数，对甩负荷过渡过程进行了仿真计算和分析。     

水力系统模型对电力系统暂态稳定分析的影响

导出了用于电力系统暂态稳定分析的水轮机模型和计及弹性或刚性水击时的引水系统模型。通过对长江三峡电力系统在大扰动下过渡过程的分析，详细讨论了在不同水流惯性时间常数和管道反射时间常数条件下，水力系统的三种模型（简化模型、刚性水击模型和弹性水击模型）对电力系统暂态稳定分析的影响     

某水电站压力前池不同模型过渡过程的计算对比

引水明渠作为输水系统的水电站通常设有压力前池.在过渡过程工况,前池内的水位会发生急速变化,影响工程的安全稳定运行,需要计算前池内的最高、最低水位.本文针对某具有长引水明渠的引水式电站的压力前池,分别采用明渠和调压室两种一维模型进行数值模拟.结果表明,在长引水明渠水电站的明渠末端设置的压力前池,两种模型计算的过渡过程结果差别不大.     

水电站有压引水系统的水力模型律

一、引言水电站引水系统是水电站必不可少的组成部分,它包括进水建筑物和压力水管,在有压引水式水电站中,还可能包括引水隧洞和调压井。引水系统的水力计算是引水系统设计的一个重要组成部分,对于大中型水电站,特别是对于比较复杂的引水系统,为了取得可靠的数     

水力系统模型对电力系统低频振荡分析的影响

导出了用于电力系统小干扰稳定分析的水轮机模型和计及弹性或刚性水击时的引水系统模型。通过对长江三峡电力系统低频振荡的计算分析，详细讨论了在不同参数如，水流惯性时间常数和管道反射时间常数下水力系统的三种模型（简化模型、刚性水击模型和弹性水击模型）对电力系统低频振荡分析的影响     

长引水式水电站小波动影响因素分析

基于一维瞬变流理论,采用考虑水体弹性的特征线法对长引水式水电站小波动过渡过程的影响因素进行了数值模拟.结合某一具体的工程算例,分析了调压室面积、阻抗孔面积、电网负荷自调节系数以及调速器参数对小波动特性的影响.相应的计算结果表明:对于长引水式水电站,调压室面积越大,小波动稳定性越好,满足小波动稳定性所需调压室断面积应大于托马临界稳定断面;阻抗口面积越小,越有利于改善小波动的调节品质;电网负荷特性能显著改善小波动稳定性及调节品质;在满足小波动稳定性的前提下,调速器参数取值越小,小波动调节品质越好.     

圆管型与廊道型气垫式调压室水力性能比较

针对廊道型气垫式调压室的罩式闭气结构比较复杂而且施工难度较大的特点,提出采用水平圆钢管型洞室代替常用的长廊道型洞室的新型气垫式调压室方案.以四川某水电站气垫式调压室为例,经大波动过渡过程计算和小波动稳定性分析,比较2种不同体型气垫式调压室的水力性能和运行稳定性.结果表明:在洞室横断面面积相等的情况下,圆管型气垫式调压室的小波动稳定性较好;调压室内水位波动幅值较小、最大气体压力和机组蜗壳进口最大压力较小,其大波动水力性能也相对较好.     

电压稳定动态负荷建模综述

电压稳定是电力系统稳定性分析的重要组成部分,电压稳定分析与负荷动态特性密切相关,建立适当的负荷模型有利于电压稳定性实现准确分析。本文介绍了电压稳定与负荷的动态关系,对电压稳定负荷建模的研究现状和存在的问题进行总结,指出建立负荷的机理模型对于研究电压稳定的必要性。     

集中供热管网的非稳态水力建模与动态响应分析

建立了单个供热管段的非稳态水力模型,导出了该非稳态水力模型的解析解,分析了管道长度、管径、进出口压差变化时管道流体的动态响应特性.当单个管道的进出口压差变化相同,管道的长度越长、管径越大时,管道的流量响应时间越慢;对于相同规格的管道,当管道的进出口压差变化越大时,管道流体的动态响应速度越快.在单个管段的非稳态水力模型的基础上,结合图论的方法建立了集中供热管网的非稳态水力模型,并构建了该模型的数值求解方法.该模型考虑管网运行调节时阀门开度或水泵转速改变等影响动态响应时间的因素,提出的非稳态水力模型和求解方法为热网进行频繁、大范围水力工况调节过程中各热力站流量的动态响应分析提供了支持.对一个实际热网的动态水力进行了分析,结果表明:当热网中的阀门开度不变、热源泵转速发生变化时,距离热源越远的热力站的流量动态响应时间越长;同样地,当热网中热源泵的转速不变、改变某一热力站的阀门开度时,距离热源越远的热力站的流量动态响应时间越长.     

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     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with