光弹贴片法对复合材料混合型应力强度因子的测定

本文介绍用光弹性贴片法测试正交各向异性单向板混合型应力强度因子K_Ⅰ、K_Ⅱ值.光弹薄片可直接粘贴于工程构件,试验表明:此法可作为对复合材料进行光弹性断裂分析的工程应用近似方法.     

光弹贴片法检测复合材料残余应力

采用钻孔法结合光弹贴片实测正交异性复合材料板小孔周围释放应力应变场,简要推导光弹等差线条纹级数与测点残余应力的关系式,并以碳/环氧复合材料板为实例,探讨更简便易行的残余应力检测方法。在实验技术上,将聚碳酸酯贴片的单侧表面镀金属铝膜,以提高贴片的反射效率。实验表明,钻孔法结合光弹贴片测量可有效地分析复合材料残余应力问题。     

正交各向异性矩形截面梁（板）的弹性扭转问题

对工程中常见的正交各向异性梁及正交各向异性板的扭转问题进行力学分析，采用Ｓ－Ｖｅｎａｎｔ假设，引入Ｐｒａｍｄｔｌ应力函数，给出该问题的弹性理解解，其结果可以作为复合材料结构力学的一个必要补充。     

正交各向异性单层板轴向拉伸时圆孔边应力集中的研究

本文对复合材料的孔边应力进行了理论计算与测试研究。文中引用了正交各向异性单向板圆孔边应力集中系数的理论计算式。介绍了用光弹贴片法对拉伸时圆孔边应刀集中系数的实测．测试值中考虑了贴片的增强效应与泊松比失配影响。最后对测试值与理论值进行了比较，符合较好。     

含有弹性核复合材料板的应力分析

用解析与数值法分析了含有多个弹性核复合材料板的应力。将各向异性板和各向同性板的应力函数分别用劳伦斯级数和麦克劳林级级数表示，并利用节点配置法，确定它们的应力函数从而求出了复合材料板的应力分布。     

光弹性贴片法的实验研究

本文介绍了光弹性贴片法的有关实验技术和实验方法,提供了一种能够“软成形”的贴片材料和成功的黏结技术,并着重研究了正交式反射偏光系统的调整。对贴片的厚度效应,加强效应的研究提供了光弹性贴片法的实验基础,特别是对于板壳结构的应用。此外,还探讨了斜射法在光弹性贴片法中的应用。有孔板条的拉伸和弯曲的典型实验以及对有孔壳体应力分析的实际应用说明所述实验技术和实验方法是有效的。     

弹性地基上正交各向异性板的低速冲击响应

为了研究弹性地基上钢筋混凝土板在冲击荷载作用下的应力及位移特征,文中以弹性地基与正交各向异性板的接触作用为分析模型,采用显式有限元方法建立了弹性地基与四边自由的正交各向异性板冲击作用的分析模型,计算了弹性地基和正交各向异性弹性板的应力场及位移场。数值模拟结果表明:四边自由的正交各向异性板在冲击荷载作用下其底部受拉,顶部受压,其应力分布特征与薄板弯曲的应力分布特征相近,板中最大应力对称出现在距板底中央的1/3处;地基沉降主要出现在与板接触的有限区域内,且发生在距地基表面的0. 0～1. 2 m深度范围内。本文的计算结果可为评估弹性地基及正交各向异性板在冲击荷载作用下的安全性提供计算依据。     

光弹贴片法测定复合材料构件应力强度因子

本文介绍了贴片法对正交各向异性单向板Ⅰ型裂纹应力强度因子的测定方法.在测试结果的运算中,从理论公式对增强效应进行了估算,且在试验技术上考虑了增强效应与泊桑比不匹配问题,试验结果表明:用贴片法测试复合材料的K_1在技术上可行,精度基本上可符合工程需要,在解决复合材料的断裂研究上有一定的参考价值.     

正交各向异性钢筋混凝土板的应力及应变分析

为了研究正交各向异性材料的应力、应变及弹性模量等力学参数,本文从材料的物理力学特性出发,推导了正交各向异性材料的弹性本构方程。用有限元分析软件模拟得到了正交各向异性钢筋混凝土板在自重与受荷作用下的应力、应变及板中挠度值。对比分析了视钢筋混凝土板为各向同性时的应力及应变情况。发现2种情况下的应力、应变及板中挠度值与实验数据均较接近,因此,本文的有限元分析方法是可行性的。由于2种情况下模拟结果相近,因此可视正交各向异性材料为各向同性进行分析,以简化分析过程。     

光弹贴片法加强效应的修正

本文探讨了光弹贴片法在平面应力及平面弯曲问题中加强效应的修正理论,并提出了平面应力与平面弯曲组合问题加强效应修正的三种方法,可供实际测定时使用     

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.     

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