汽轮机转子热应力的在线监控模型

汽轮机转子热应力是由蒸汽温度的变化引起转子体中温差而形成的。对上述过程分别建立复频域动态数学模型,经综合后得到转子热应力对蒸汽温度变化率的相应模型。并以某一机组的实际启动过程为算例,与有限元模型作了仿真比较,结果表明模型具有较高的精度。为了大幅缩减计算量,应用“主导极点”概念对所得模型作了合理简化,为热应力的在线监控提供了一个易于实现的通用模型。该模型对放热系数及转子材料物性参数的变化具有自适应能力。     

大型汽轮机调节级动叶栅温度场分析

超临界汽轮机调节级承担着较大的焓降,温度梯度更大,会引起高压缸各级相当大的热应力和热变形,特别是调节级动叶栅及调节级处的转子表面的温度变化较为剧烈,这将影响机组的启停及变工况速度,不利于机组的调峰。而本文以某600MW超超临界汽轮机为例,建立了调节级动叶栅的有限元分析模型,模拟出整个动叶栅及转子表面的温度分布图,为研究超超临界汽轮机各级叶片和转子热应力的分析提供了理论基础,并为机组的启动优化提供了参考。     

汽轮机转子寿命的研究

介绍了汽轮机转子温度场、热应力及寿命损耗的数学模型及实现其实时监测的方法,结合300MW供热凝汽机组,对其寿命进行分析。     

汽轮机的长期动态模型与仿真

为了全面、可靠、快捷地研究调峰及负荷变化过程中各种锅炉汽轮机发电机组的长期动态特性,通过合理的机理分析和简化建立起汽轮机本体及其汽水系统回热加热器的简化数学模型,并以此为工具对某600MW超临界机组的长期动态特性进行了仿真研究。结果表明:本模型能较为合理地反映锅炉给水流量和新蒸汽压力变化对汽轮机抽汽的压力、流量以及机组功率变化的作用和影响,为各种锅炉汽轮机发电机组的长期动态特性研究提供了一个十分简便、新颖的数学模型。     

国产汽轮机调峰运行方式的选择

阐述了火力发电厂大型汽轮机调峰运行的必要性,论述了国产汽轮机三种调峰方式的特点并进行了分析比较,指出电厂应根据自己的机组情况和技术力量,选择合适的调峰运行方式,在条件允许的情况下对机组采用发动机工况运行方式进行调峰是一种较好的调峰方法。     

超超临界汽轮机调节级动叶栅热应力分析

本文以某600MW超超临界汽轮机为例,应用ANSYS建立了调节级动叶栅和所在转子凸台的有限元分析模型,得到了变工况下应力分布规律,了解动叶栅和所在转子凸台应力最高的部分,为研究叶片和转子热应力的分析提供了理论基础,并为机组的启动优化提供了参考。     

热力发电厂300MW汽轮机组动态热耗的仿真研究

应用理论分析法建立了３００ＭＷ再热凝汽式汽轮机组非线性动态数学模型；同时进行了当入口参数，低温再热器入口烟温在机组稳定工况下小范围扰动时的汽轮机组热耗率的动态仿真研究，并且对汽轮机组的汽耗及热力发电厂煤耗，效率也进行了动态研究，最后得出了仿真结果。     

一种仿真系统数学模型的建模方法

建立精确的数学模型,是仿真系统开发成功的关键.为了对未知结构和动态外特性的对象进行有效的仿真,文章提出一种称为"复合法”的建模方法建立系统的数学模型.该方法可在仅知对象静态外特性的情况下,综合利用相近设备的机理和对象的"操作知识”,建立满足运算速度和精度要求的数学模型,能够满足一般仿真培训系统建模的需要.在大型冷冻站制冷控制仿真培训系统的开发中,应用该方法建立YORK公司螺杆式冷冻机的数学模型,取得了满意的效果.     

热力发电厂300MW汽轮机组动态热耗率的仿真研究

应用理论分析法建立了３００ＭＷ再热凝汽式汽轮机组非线性动态数学模型；同时进行了当入口参数（主蒸汽压力、温度与流量）、低温再热器入口烟温在机组稳定工况下小范围扰动时的汽轮机组热耗率的动态仿真研究，并且对汽轮机组的汽耗（ＳＳＣ）及热力发电厂煤耗（ＳＣＣ）、效率（Ｅｔｐｐ）也进行了动态研究，最后得出了仿真结果     

汽轮机调节系统改造设计及应用

汽轮机机械液压系统具有固有的缺陷,如迟缓率大、动态调节品质差、控制精度低以及操作繁琐、运行、维护十分不便等,解决这些问题均要求采用一种全新、先进调节系统来取代原有的机械液压式调节系统。本文论述了汽轮机调节系统改造的必要性,详细阐述了汽轮机调节系统的改造方案,并以100MW汽轮机DEH改造为例,说明了汽轮机调节系统改造的具体方案设计,最后论文分析了调节系统改造后的安全性。实践证明改造后的机组控制可靠,实现了机组的AGC功能,加快了机组的快速调峰能力。     

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.     

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     

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     

Journal of Donghua University ( English Edition) Contents of Volume 31

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