环形振子的扭转振动等效电路及有限元模态分析

基于机电类比原理,对弹性薄圆环振子的扭转振动进行了研究,建立了圆环振子平面扭转振动的机电类比等效电路模型,从等效电路得出了其扭转振动频率方程及共振频率表达式,给出了薄圆环振子频率方程的数值根与其半径比的拟合关系曲线,通过有限元(FEM)模态分析表明,理论与FEM仿真结果符合较好,对环形扭转振子的工程设计具有参考价值.     

径向振动压电陶瓷薄圆盘振子的机电等效电路与共振频率研究

对轴向极化压电陶瓷薄圆盘振子径向振动进行了理论和实验研究.推出了其机电等效电路,得出了振子共振和反共振频率方程,探讨了振子共振和反共振频率与材料参数之间的依赖关系,给出了压电陶瓷薄圆盘振子的共振及反共振频率与其泊松系数之间的解析关系.实验结果与理论计算符合较好.     

薄圆环振子的超声扭转振动及其等效电路研究

对薄圆环振子的扭转振动进行了研究,导出了其等效电路,从等效电路得出了其扭转振动频率方程及共振频率表达式.给出了薄圆环振子频率方程的数值根与其半径比的拟合关系曲线.通过对有限元(FEM)模态的分析表明,理论与FEM仿真结果符合较好,对环形扭转振子的工程设计具有参考价值.     

幂函数剖面薄圆环振子的扭转振动特性

对剖面厚度按幂函数变化的薄圆环振子的扭转振动进行了理论分析,导出了其等效电路;进而由等效电路得出了扭转振动频率方程及共振频率表达式;探讨了环形振子第1、第2阶共振频率及角位移放大系数与其半径比的关系;给出了薄圆环振子第1、第2阶共振频率及放大系数与其半径比的拟合关系曲线．通过有限元（FEM）模态的分析,表明理论结果与FEM仿真结果吻合,对环形扭转振子的工程设计具有参考价值．     

薄圆环扭转振动及其等效电路研究

研究了各向同性薄圆环振子的扭转振动，推导了薄圆环振子扭转振动的波动方程和机电等效电路．在此基础上，得出了振子空载时共振频率方程和振子共振频率的表达式．利用数值方法，求出了共振频率的理论值；并利用Ansys软件，对薄圆环振子进行了有限元模拟，得到了其共振频率的模拟值．     

径向复合功率合成超声振动系统

对径向复合功率合成超声振动系统进行了研究.该系统由纵向超声换能器与变厚度剖面圆盘径向耦合而成.基于机电类比原理,推导出系统的楔形剖面圆盘径向振动等效电路及其共振频率方程,并得出其位移振幅放大系数的表达式,给出其第1、第2阶径向共振模式下振幅放大系数与其半径比的关系;探讨了圆盘振子第1、第2阶径向共振频率随其半径比的变化关系.理论及有限元结果表明：圆盘的位移振幅放大系数存在一个极大值,其第2阶共振模式比基频具有更大的振幅放大系数.对合成系统的共振频率进行测试,结果表明,理论与实验结果吻合较好.     

弯曲振动超声换能器的振动特性及辐射声场研究

对弯曲振动气介式超声换能器的振动特性及辐射声场进行了研究.该换能器由中心激励的弯曲振动圆盘及纵向振动夹心式压电陶瓷换能器组成.对圆板的轴对称弯曲振动进行了分析,得出了边界简支薄圆板的共振频率方程,推出了夹心式换能器与弯曲圆盘复合振子的机电等效电路及总体频率方程,并求出了其辐射远场声压分布指向性的解析表达式及换能器辐射近场的三维声压分布.结果表明,弯曲圆盘换能器的近场声压分布同样具有指向性,且主要分布在与换能器横向尺寸相同的空间内.对于弯曲振动圆板不同振动模式,等效电路参数及声场分布和指向性不同.     

纵弯振动换能器共振特性及有限元仿真

利用夹心式换能器的设计理论,将纵振换能器与薄圆盘作为整体进行分析,做出复合换能器的等效电路图,推导圆盘弯振的等效弹性常数的通式,进而得到复合换能器的共振频率方程.按给定的换能器尺寸,利用计算机计算出了其各阶共振频率.并与单独振动体的频率间距作以比较,发现通过两种振动模态的耦合,大大拉近了各阶振动频率峰值的间距.利用ANSYS模拟实验进行了验证.     

圆形超声辐射器的多维耦合振动

用解析方法研究了圆形超声辐射器的多维耦合振动,通过引入振动轴向振动与横向振动之间的机械耦合系数,导出了辐射器耦合振动共振频率方程的解析表达式,由此不仅能够得出振子的轴向共振频率,而且可以得出震子的径向共振频率,与一维理论的结果相比,本文得出的结果与实测值更加符合,实验表明,振子共振频率的测量值与计算值符合很好。     

矩形压电陶瓷振子的耦合振动

利用等效弹性法分析了矩形压电陶瓷振子的二维耦合振动,通过引入等效弹性常数和二维耦合系数得出矩形压电陶瓷振子的共振频率方程和耦合系数方程,探讨了耦合系数、共振频率与压电振子宽长比的依赖关系。利用数值法对压电振子的振动特性进行了模拟及仿真,并与解析结果进行了比较,二者吻合较好。最后用实验进行验证,实验结果与仿真结果有很好的一致性。     

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     

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