压电石英晶体扭转效应的ANSYS分析

在通过各向异性弹性理论和麦克斯韦理论研究Y 0°切型石英晶片的扭转效应,得出其扭转应力场和非线性极化电场分布的基础上,利用AN SY S的耦合场分析验证了压电扭转效应的存在.通过建模、划分网格、求解和后处理几个典型的步骤得到Y 0°切型石英晶片的应力值和极化电压,显示其与所加载的扭矩值成明显的线性关系.而采用分割电极的方法进行实验,其数据也证明了理论分析及有限元分析的正确性.     

基于压电石英晶片扭转效应的扭矩传感器原理与研制

发明了一种基于压电石英晶片扭转效应的扭矩传感器,介绍了其理论基础、扭转束缚电荷密度分布规律与电极的粘贴方法,以及扭矩传感器性能标定.该传感器同其他石英扭矩传感器相比,突出特点是采用石英晶片的扭转效应而不是通常采用的剪切效应来建构的.整个扭矩晶组仅由3片普通Y0°切型的石英晶片组成,采用分割电极法布置检测电极,晶组的组成方式能够减小或避免径向力和轴向力的横向干扰,同时又能提高传感器的灵敏度.经标定该传感器的技术指标全面达到CIRP-STCC规定的测力仪使用标准.     

压电晶体最大特征系数切向判定方法

利用特征系数最大的压电晶体切型，可以获得较强的压电效应．给出了一种利用最优化方法确定特征系数最大的压电晶体切向的计算方法．压电晶体各系数矩阵的矩阵元随不同的旋转切割方向而变化，对二次旋转切割，它们是两个旋转角的连续函数．以压电系数为例，给出了二次旋转后各矩阵元的表达式和部分矩阵元随两个旋转角变化的三维曲面．各矩阵元的绝对值均存在一个最大值，有些最大值比原始坐标系中的最大值要大．针对LiNbO3晶体的压电系数矩阵，利用所给出的方法计算了每一矩阵元的最大值和相应的切割方法(2个旋转切角)．     

硅酸镓镧晶体声表面波压力敏感特性研究

针对采用新型压电材料硅酸镓镧(LGS)研制声表面波高温压力传感器的需要,利用微扰理论对LGS在双旋转平面内的压力敏感特性进行了理论分析,以等高线的形式给出了LGS在二维旋转平面内的压力对敏感系数.结合温度及机电耦合特性,优化出了适合压力传感器的切向范围,并对欧拉角为(0,150°,22°)的切向基片的压力敏感特性进行了实验研究.验证了谐振频率的变化与外界压力成线性关系,且理论与实验结果趋势基本一致.     

基于PDT的压电双晶片传感特性分析

基于ANSYS的概率设计技术对压电双晶片位移型传感器的位移特性和灵敏度特性进行了有限元分析.求得了压电双晶片位移传感器灵敏度与双晶片的材料参数和几何尺寸的关系.分析结果对于压电双晶片传感器的设计和优化具有重要的工程意义.     

YDS-Ⅲ79B,YDS-Ⅲ79K型石英晶体三维力传感器的设计与研究

本文着重叙述了三维压电石英力传感器的原理和优点，介绍了所研制的 ＹＤＳ－ Ⅲ７９Ｂ及ＹＤＳ－Ⅲ７９Ｋ型三维力传感器的结构设计、工艺特点、压电效应与晶片切 型的选择，并对传感器在力、电转换过程中可能出现的一些问题，从各个方面进行了 分析，指出了解决的途径和可能采取的方法。 本文最后介绍了该传感器的标定及其技术指标、三维力测试系统及其应用举 例．     

二阶线性矩阵微分方程的振动性定理

研究了二阶微分方系统Ｙ＾〃＋Ｑ）ｔ）Ｙ＝０，ｔ∈「ｔ０，∞」，其中Ｑ，Ｙ是ｎ×ｎ实连续矩阵函数，且Ｑ（ｔ）是对称矩阵，ｔ∈「ｔ０，∞），给出两个该方程振动的判定准则。     

α—AL2O3单晶体的X射线衍射仪法分析

以α－ＡＬ２Ｏ３单晶体为例，探索了现代Ｘ射线衍射仪法分析技术在晶体取向和晶向偏离角测试方面 应用。采用方法测试的晶面的晶向偏离角为ψ＝４．９７°。经ＴＥＭ电子衍射菊池线测试晶面晶向偏离角Δθ＝５．１１°，误差小于０．２°。表明本文提出珠Ｘ射线衍射法测试单晶体向偏离角具有简捷，精确及可靠性高的优点。     

石英谐振器力灵敏度温度系数特性分析

力灵敏度温度系数是石英谐振器产生温漂的主要原因之一，而且这种温漂不能用差频方法消除，因此，它是影响石英谐振式力传感器测量精度的主要原因．文中给出了测量误差与力灵敏度温度系数之间的定量关系，并得到实验验证．阐述了力灵敏度温度系数的物理意义，分析确定了标定温度的方法．在一定温度范围内使用的石英晶体谐振器，既要有一定的分辨率，又要使其测量结果不受温度影响，为此提出了石英谐振器最佳取向选取原则．根据这一原则，找出了ＡＴ切型晶片用作力敏元件时的最佳施力方位角．为提高石英谐振式力传感器的测量精度提供了一个理论基础．     

基于应力敏感系数的硅酸镓镧晶体声表面波应力敏感特性

从叠加偏载的运动方程出发,借助微扰理论推导了压电晶片上声表面波波速的应力敏感模型,提出了应力敏感系数的概念,计算了硅酸镓镧在二维旋转空间的应力敏感系数.讨论了应力敏感系数的应用,在平面应力条件下提出并验证了仅用2个系数(1α1 2α2=0)就可以方便地确定出晶体的应力补偿切向.通过对石英和硅酸镓镧两种晶体的理论计算和实验比较,证明了所提理论和方法的正确性.     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

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