超声波精密切削基本特性的研究

在论述超声波振动切削特点的基础上，指出国内目前所使用的磁致伸缩换能器存在的问题，从而提出用新型电致伸缩超声波车削装置代替现有的磁致伸超声波车削装置进行精神切削的新方法。并用新型超声波车削装置进行了较系统的试验研究。得同超声波精密切削的基本特性。     

超磁致伸缩材料的特性参数测量

超磁致伸缩材料（GMM）是一种新型的功能材料,其磁致伸缩系数与磁场强度、温度、压力等有关。以超磁致伸缩高速响应电磁阀的研究为背景,介绍超磁致伸缩材料特性参数的测量方法,及适用于超磁致伸缩材料特性参数测量的测试装置。     

超磁致伸缩材料的特性参数测量

超磁致伸缩材料（GMM）是一种新型的功能材料,其磁致伸缩系数与磁场强度、温度、压力等有关。以超磁致伸缩高速响应电磁阀的研究为背景,介绍超磁致伸缩材料特性参数的测量方法,及适用于超磁致伸缩材料特性参数测量的测试装置。     

国内外超磁致伸缩材料及作动器的研究

超磁致伸缩作动器具有推力强、反应快和分辨率高等特点,在精密定位、精密驱动、机器人、微型阀等领域展现了广阔的应用前景本文在介绍超磁致伸缩材料及其应用的基础上,分析了国内外超磁致伸缩作动器的研究动态、应用状况等,并对几类超磁致伸缩作动器的原理、结构进行了阐述,最后提出了超磁致伸缩作动器的四个研究方向。     

超声波振动切削装置实用设计研制法概要

本文简要介绍超声波振动切削装置设计研制的基本原则和实用设计研制方法。介绍了振动切削用发生器的性能特点及其保证方法,磁致伸缩换能器、变幅杆和弯曲振动杆等谐振元件的简便准确算法及设计、制造中的一些问题,可拆卸元件连接的基本原则和模式,谐振元、部件和装置的测试和试验方法。指出装置安装调试注意事项。对存在问题和努力方向作了探讨。比较系统地介绍了有关的文献资料。     

大负载精密驱动超磁致伸缩直线电机动力学建模与仿真

基于一种新型的精密大负载超磁致伸缩直线电机进行了整机动力学建模和仿真,尝试分析巨磁致伸缩直线电机的频率特性和负载特性,提供了一种对于尺蠖运动超磁致伸缩直线电机进行整机建模和性能分析的有效方法. 在建模过程中,采用Jiles Atherton磁滞模型以补偿磁滞回对直线电机输出的影响,并提出了直线电机驱动大负载时的滚动摩擦修正. 通过建模与仿真,验证了直线电机结构设计方案的可行性. 仿真和实验对比结果表明,该动力学模型实现了超磁致伸缩直线电机的变激励、变负载运动的准确模拟.     

GMA再生型颤振系统的稳定性及其控制

综合考虑再生型颤振对工件及超磁致伸缩微致动器的影响,建立了超磁致伸缩微致动器车削颤振系统非线性动力学模型。根据Lyapunov第一次近似稳定性定理及霍尔维茨判据对其进行了稳定性分析及控制研究,讨论了系统参数对GMA颤振系统稳定性的影响。同时采用简单自适应控制方法对颤振系统进行了控制研究。结果表明:车削的极限宽度、工件的质量及其等效刚度对系统的稳定性有明显的影响;简单自适应控制方法可有效抑制再生型颤振对系统稳定性的影响。     

GMA再生型颤振系统的稳定性及其控制简

综合考虑再生型颤振对工件及超磁致伸缩微致动器的影响,建立了超磁致伸缩微致动器车削颤振系统非线性动力学模型。根据Lyapunov第一次近似稳定性定理及霍尔维茨判据对其进行了稳定性分析及控制研究,讨论了系统参数对GMA颤振系统稳定性的影响。同时采用简单自适应控制方法对颤振系统进行了控制研究。结果表明：车削的极限宽度、工件的质量及其等效刚度对系统的稳定性有明显的影响;简单自适应控制方法可有效抑制再生型颤振对系统稳定性的影响。     

超磁致伸缩执行器温控系统的设计与实现

为了实现超磁致伸缩执行器(GMA)精密的位移控制,需要采取一定温控设施保证超磁致伸缩材料(GMM)工作在特定温度情况下;针对超磁致伸缩材料对温度的敏感性,在GMM智能构件的基础上提出了一种改进的强制水冷温度控制策略;利用单片机控制系统实现了对超磁致伸缩执行器的温度控制,实验结果表明了该控制策略可以保证GMA工作在恒温,验证了策略的有效性;对超磁致伸缩材料微驱动应用具有实际的工程意义。     

超磁致伸缩材料换能器的实验研究

采用超磁致伸缩材料 Terfenol—D 作为换能器中制动元件,将在一定预压应力下处于阶跃段的磁致伸缩棒简化为磁场强度与磁致伸缩应变的单输入单输出的线性系统。以静态试验数据为基础,建立等效的动态磁致伸缩模型,对自行设计的超磁致伸缩大功率换能器进行了试验研究,该装置具有功率大、适用频带宽、峰值尖锐余振小等特点,为实际开发换能器产品提供了设计依据。     

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     

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