柔性铰链微夹持机构的研究

在研究柔性铰链的基础上，介绍了平面柔性铰链微夹持机构的设计与制作，并对此进行了张合实验．利用解析法和实验，分别得出了平面柔性铰链夹持机构的放大倍数和总张合量．通过调整杠杆机构各个臂长之间的关系，就可以改变微夹持机构的放大倍数和输出的大小，夹持部分的张和量是输入位移的96倍。研究结果表明，平面柔性铰链微夹持机构的输入和输出位移具有良好的线性度，放大倍数可以根据需要进行调整．采用压电陶瓷作为动力组件，通过对压电陶瓷施加电压的调节来精确控制其张合量的大小，可用于对微型零件的操作，因此具有精度高、易控制、性能稳定的优点，可集成于微型装配系统中，并具有广阔的应用前景．     

前端开孔的大振幅柱型超声变幅杆

提出了一种前端开横向矩形通孔的柱型变幅杆.利用有限元方法计算了谐振频率下振幅放大倍数和输出端面位移分布,研究了孔尺寸对变幅杆谐振频率的影响并优化了孔尺寸,得到最大放大倍数,与传统变幅杆相比放大倍数有大幅提高.分析了优化前后变幅杆的应力.将变幅杆与换能器相连接,激光测振仪测试了振动系统的频率、振型、变幅杆的输出端面位移分布及相对于变幅杆输入端的振幅放大倍数,测试结果与有限元计算结果一致.测试结果还表明激励电压与变幅杆输出端位移具有线性关系.     

菱形微位移压电作动器的输入输出线性建模

针对某定位装置的位移输出问题,研究了一种新型菱形微位移压电作动器,该压电作动器包括压电陶瓷、菱形微位移放大机构以及柔性铰链部分。对菱形微位移放大机构的放大系数进行了分析,发现该放大机构具有把压电堆的原始位移输出从30μm放大到100μm的能力,放大倍数与菱形环自身夹角θ有关,并且在压电堆输出范围内为比例放大,这些结果可以为更大放大系数的菱形环设计提供依据。建立了该菱形微位移压电作动器输入输出关系的理论线性模型,并将线性模型的模拟结果与实验结果进行了对比,证明该压电作动器线性模型具有较好的精度,能比较准确地反映微位移压电作动器的输入输出关系。     

压电谐波电机单级杠杆式位移放大机构的有限元分析

压电谐波电机是一种利用压电陶瓷驱动器、位移放大机构以及控制系统代替传统的波发生器的新型谐波电机.利用ANSYS软件对压电驱动器的单级杠杆式弹性铰链位移放大机构进行了有限元分析,得到了放大机构的变形及应力图,分析了影响位移放大倍数的因素以及改进措施.     

一种微位移柔顺放大机构的优化设计

基于柔性梁的动刚度矩阵以及矩阵位移法建立了一种微位移柔顺放大机构的伪静态参数化模型.该模型可以对新机构进行快速化运动预测和参数化运动分析，并且可以得到位移放大率的解析模型.通过模拟退火算法优化结构的尺寸与形状得到了一种新的机构，它的放大率相比于原始构型增加了9%且固有频率为409Hz，与有限元结果对比相对误差小于2%，验证了模型的准确性.分析了在负载与输入位移共同作用下新机构的放大率变化规律以及结构关键节点处的加工误差对输出位移的影响.结果表明，模型顶点与输出端的X方向加工误差对输出位移的影响最大.     

新型3-DOF柔性并联微操作平台的研究

根据杠杆原理设计的新型二级杠杆放大器,在此基础上基于3-PRC并联机构提出一种具有空间解耦的新型三维移动并联柔性微位移放大机构.该机构由三个相同的支链采用正交的方式与动、静平台相连,以压电陶瓷作为驱动装置并内置在二级杠杆放大器中,能够使机构实现微纳米级的运动.通过理论计算和仿真分析对新型二级杠杆放大器和并联柔性微位移放大机构进行了研究,结果表明该机构具有良好的运动解耦性和较高的精度.     

一种新型微位移放大机构设计与特性分析

基于柔性铰链的传导性,运用杠杆原理设计了一种全对称结构的二级微位移放大机构,该机构具有无附加方向上位移及运动精确等优点.建立了微位移放大机构的仿真模型和运动学模型,给出了工作原理;根据机构学原理推导出了机构位移放大比,运用ANSYS13.0对该机构进行有限元仿真,得出了实际输出位移、放大比及该机构的固有频率.放大比误差为7.46%;误差分析主要原因为在理论模型中采取简化分析,忽略了柔性铰链伸长变形导致的中心偏移,并且假设了除去柔性铰链外,其他的部分全为刚性.本文研究为微位移放大机构的实际生产提供了理论依据.     

多维微传动平台设计及基于RPY角的运动特性分析

为了满足精密制造领域对于传动平台多自由度及大行程的要求,基于空间机构学,设计了由压电陶瓷驱动柔性铰链导向的六自由度微传动平台.针对压电陶瓷输出位移小的缺点,设计桥式机构对其输出位移进行放大,并利用线切割对传动平台进行一次性加工,得到具有大行程的一体式传动平台.通过齐次坐标变换得到了补充修正后的RPY(滚动-俯仰-偏转)角姿态描述方法,利用此方法分析传动平台的运动特性,通过虚功原理和坐标变换理论,建立了微传动平台的运动学模型,得到了压电陶瓷驱动位移与传动平台运动位移之间的映射关系,以及微传动平台6个方向的静态刚度及其变化规律.利用ANSYS12.0对传动平台进行有限元仿真,并搭建实验平台进行实验测试,实验结果与理论模型和仿真结果的对比分析验证了理论模型的正确性及平台结构的合理性.     

压电式微驱动器的应用研究

在分析常用微驱动器的基础上,设计了一种压电式微驱动器,采用柔性铰链机构实现无机械摩擦、无间隙的高灵敏度微驱动,利用柔性铰链杠杆放大原理增加了叠层式压电陶瓷位移输出．满足了在激光测量系统中作为移相器的工作要求．文章对柔性铰链机构进行了理论分析,建立了数学模型,采用有限元分析方法优化了机构的结构参数．     

桥式放大机构放大率的计算与分析

针对传统桥式放大机构放大倍数小、定位精度低的不足,设计了一种新型桥式放大机构,可以很好的消除耦合运动,增加放大倍数和提高定位精度.利用桥式微位移放大机构的对称性,建立了1/4桥式放大机构的数学模型,推导了桥式放大机构放大率的理论计算公式,公式在表达上较为简洁,有利于简化桥式放大机构放大率的计算和分析.计算了新型桥式放大机构的位移放大率,使用有限元分析软件ANSYS Workbench进行了模拟仿真,与理论计算所得出的结论进行比较,并对误差进行分析,从而验证所推导公式的准确性.     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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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