拱圈淹没深度对拱桥内力影响的计算研究

提出了在桥梁结构计算中利用有限元法计算水浮力的模型和方法,所提出的内力影响系数x直线反映了不同淹没深度下水浮力对拱桥内力的影响,在此基础之上对两种类型的拱桥进行实例分析,根据计算结果讨论了山峡库区水位升高后拱圈淹没深度对拱桥内力的影响,得出可以适当提高拱圈淹没深度的结论,但当淹没深度在矢高的1／4以上时,在设计中应该充分考虑水浮力的影响．     

淹没磨料射流的空蚀能力分析

淹没磨料射流的空蚀能力决定着磨料射流在水下切割能力的强弱.采用高压密闭容器模拟水下环境,利用磨料射流系统、数码摄像系统,实验研究了淹没磨料射流的紊流特性,进行了空蚀能力的理论分析.探讨了淹没磨料射流紊流系数随泵压、围压的变化规律.研究表明,文丘里型空化喷嘴的射流系统中,相同条件下,5 MPa以上淹没磨料射流的空化数较纯水空化射流大,磨料的存在使淹没磨料射流空蚀能力降低.     

进水口前立轴旋涡的试验研究

通过分析旋涡形成的影响因素,建立了立轴旋涡的形成和类型,与佛汝德数、环量数和淹没水深三个参数的关系式. 自制了能改变进水口尺寸、型式、边界条件和水流条件等影响立轴旋涡的实验装置. 分析测得的试验结果,对底部和侧部两种进水口提供不同的系数,有利于针对实际工程中进水口的具体形式,作为估算临界淹没水深的参考.     

水利工程防洪经济效益的简易分析计算法

介绍一种水利工程防洪经济效益的计算法。根据超标准流量绘制流量～淹没面积及淹没面积～淹没损失曲线,借助公式可以计算出防洪效益及淹没损失值,比较直观,有推广应用价值。     

淹没深度对离心式叶轮模态参数的影响

离心式叶轮结构振动及其幅值受周围水体附加质量和阻尼的影响.为了明确不同淹没深度对离心式叶轮动力响应特性的影响,开展了数值计算和实验研究.基于声固耦合方法,开展了空气和不同淹没深度条件下叶轮的模态分析;通过锤击法获得了在空气和不同淹没深度条件下的叶轮结构响应参数,并评价了固有频率的数值预测精度;根据数值计算和实验结果,构建了结构振型、附加质量参数和阻尼参数随淹没深度的变化规律.结果表明:随着淹没深度增大,结构振型未发生改变;但叶轮附加质量系数和阻尼比都呈线性增长趋势;完全淹没时,水体附加质量及阻尼比分别为空气中的0.39倍和1.76倍.      

新生代南海北部碳酸盐岩台地的淹没事件研究

碳酸盐岩台地广泛发育及其淹没事件是南海新生代地层的重要特征之一。通过钻孔揭示的地层，古生物等资料对位于南海北部的东沙和西沙碳酸盐岩石地发育，演化及其淹没层序进行了分析，首次提出了本区自新生代以来经历了三次大的淹没和若干次小的淹没事件，分别相当于Haq提出的三级和四级层序。     

基于DEM的有源淹没算法设计与实现——以种子蔓延法为例

 针对传统有源淹没的递归、迭代算法占用计算机资源较多,且当算法深度太深时易造成系统堆栈溢出,从而导致程序崩溃等缺点,以数字高程模型为基础,研究了给定水位条件下洪水有源淹没模型和算法,并在此基础上设计实现了种子蔓延算法。通过与原有的递归算法对比,发现该算法在一定程度上提高了计算效率和稳定性,最后在“南昌洪水淹没分析系统”中应用并得到验证。     

浅俯淹没射流水力特性

为探讨浅附淹没射流的水力特性,采用粒子成像测速技术获得水垫塘精细流场,系统分析淹没射流区和附壁射流区纵面二维流速分布规律。通过研究获得了淹没射流区和附壁射流区沿流程流速衰减和垂直于主流断面流速分布的公式。结果表明,浅俯淹没射流沿入射角射入水垫塘,射流潜底的俯角大于入射角;淹没射流区沿程流速衰减率大于附壁射流区;淹没射流区和附壁射流区沿程各垂直于主流的断面流速分布具有相似性或自保持性。     

山美水库洪水淹没分析及方法研究

在全球极端天气逐年增多的背景下,自然灾害发生的频次和强度愈来愈大。中国为防洪抗旱近年来兴建水库,而水库一旦发生洪水灾情,水库的泄洪淹没范围对下游防汛规划及减少灾害损失至关重要。以山美水库为例,基于地理信息系统(geographic information system, GIS)技术选用有源淹没方法确定山美水库遭遇3种重现期洪水泄洪的淹没范围,并利用洪水量等于淹没水量的原理,提出了一种运用二分法迭代有源淹没的淹没水位确定方法。通过输入3种不同重现期洪水量,本研究模拟出山美水库遭遇20年一遇洪水时下游淹没面积为20.04 km²,遭遇50年一遇洪水时下游淹没面积为24.42 km²,遭遇100年一遇洪水时下游淹没面积为26.07 km²。结果显示,淹没区域集中在水库下游的梅山镇、罗东镇、码头镇。研究结果可为地方政府管理洪水风险、制定防洪措施提供一定的参考。     

高陂水利枢纽超蓄淹没动态模拟及实景三维可视化

为研究水库洪水调度情况下的超蓄淹没风险,以韩江高陂水利枢纽为研究对象,基于二维浅水波方程和Villemonte堰流公式构建了库区超蓄淹没模型,模型合理可靠。考虑实际来水和调度方案的不确定性,模型中引入来水、调度方案等动态因子,实现了高陂水利枢纽超蓄淹没风险动态分析模型,并基于三维实景建模技术,实现了任意来水、调度方案下的超蓄淹没三维可视化模拟展示。研究成果可为高陂库区超蓄淹没风险预警预报、水库调度运行、避洪转移、防洪措施制定完善等工作提供决策支撑,也可为其它水库提供借鉴作用。     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has