三维弹塑性分析弹性试验解法的实现

本文采用光弹性和电测法,实例验证了三维弹塑性分析弹性试验模型的基本原理.结果表明:该弹性试验模型对结构的弹塑性分析有足够的精度,可用于工程实际.     

光弹性定向载波研究

研究了光弹性定向载波的基本原理和光强度分布,分析了由此产生载波条纹的分布规律.将光弹性定向载波器置入传统光弹性仪器中的适当位置,转动光弹性定向载波器得到包含测量主应力方向的条纹图,最终通过对光弹性条纹图像处理获得等差线级次和主应力方向,以此提高光弹性实验的精度和速度,为拓宽光测力学的工程应用创造条件.     

岩体工程中三维变弹模光弹性应力计算问题

根据光弹性实验原理,本文提出了岩体工程中变弹模光弹性实验的主要计算公式。同时还对变弹模三维光弹性应力计算问题进行了讨论。本文对于非均质岩体工程的变弹模光弹性实验计算有着一定的参考意义。     

动光弹实验中的主应力分离方法

动态光弹性是研究应力波传播的一个有效工具,已广泛地应用于工程实际,在对动光弹实验资料进行分析时,如何得到应力场的定量结果,即对主应力进行分离,是需要解决的关键问题之一。综述了目前动光弹主应力分离的各种方法和研究现状,并提出了与弹性理论相结合的主应力分离法,不仅使主应力的分离得到简化,而且可提高分析结果的合理性。     

理想裂纹尖端的光弹性应力分析

本文总结了目前光弹性法研究断裂力学中于模型试样上制作模拟裂纹所用的三种方法——机械加工,夹片和张拉法。前两种方法只能在试件上形成切口状裂缝,而第三种方法可以形成品质优良的“理想尖裂纹”(即裂缝宽度为零的尖裂纹)。本文分析了在用不同方法所形成的裂纹试件,对光弹性法实验确定K_1的影响。给出“理想尖裂纹”试件作K_1测定中所呈献的特点.实践表明,在“理想尖裂纹”试样上进行测定时,由于数据采集范围大,数值稳定性好,T—N曲线上试验点分布规律性明显,能带来高精度的测定结果。此外,文中还提出评定裂纹试样的三条质量标准。     

一类低粘度高弹性常数液晶的合成和性能的应用研究

液晶的弹性常数影响到液晶的阈值电压、响应时间、电光曲线,是一类很重要的参数,设计开发了具有高折射率、低γ_1/K_(11)的液晶单体.四环液晶可以用于提升液晶的使用温度范围及液晶的弹性常数,是混合液晶设计的一类常用的单体.设计合成、评测了一类侧向双氟三联苯四环液晶单体,并考察了其在液晶混合物中的应用,相对于常见单体,具有较大的弹性常数K_(11),K_(33)、较大的介电各向异性Δε、较高的清亮点CP,并对其表现出的性能参数与液晶分子结构之间的关系作了初步分析,通过GC-MS,~1HNMR,~(13)CNMR,DSC等分析方法对结构进行了表征.     

表面对氢负离子在梯度电场中光剥离的调控研究

利用闭合轨道理论对氢负离子体系在梯度电场和弹性表面附近的光剥离进行了研究,重点探讨了弹性表面对氢负离子在梯度电场中光剥离截面的影响.研究结果表明,氢负离子体系在梯度电场和弹性表面附近的光剥离与弹性表面的位置有关.当弹性表面距离氢负离子的距离比较远时,弹性表面对光剥离截面的影响较小,光剥离截面和只有梯度电场时的截面基本吻合;但是随着弹性表面到氢负离子距离的减小,弹性表面的影响越来越明显,光剥离截面的振荡振幅越来越大.除此之外,我们还对弹性表面位于Z0的空间和位于Z0的空间的情况进行了比较.结果表明,当弹性表面到氢负离子之间的距离给定时,弹性表面位于Z0的空间时的光剥离截面的振荡要比位于Z0的空间的情况要复杂.因此,我们可以通过调整弹性表面的位置对氢负离子在梯度电场中的光剥离进行调控研究.本文的研究对于理解负离子体系在非匀强电场和表面附近的光剥离可以提供一定的参考价值.     

人工裂缝曲率对光测应力强度因子K_Ⅰ,K_Ⅱ,K_Ⅲ影响之初探

本文用光弹性方法较系统地探讨了人工裂缝曲率半径ρ对应力强度因子K_Ⅰ、K_Ⅱ、K_Ⅲ的影响。实验结果初步表明:在ρ<0.04mm时,看来会得到K_Ⅰ较满意的结果。ρ=0.12mm时,K_Ⅰ实测值较理论值尚无显著偏差(-4.83％);ρ对K_Ⅱ影响较K_Ⅰ为大;K_Ⅲ实测值对于ρ的变化似不敏感。     

用园环裂纹拉伸试样测定钢在低温下的断裂韧性

为了用线弹性断裂力学观点研究钢的低温断裂行为,我们探索了用园环裂纹拉伸试样测断裂韧性K_(1c)的较为简便的试验方法.本文在论证该方法的同时,给出了用该方法测得的几种常用结构钢从室温至—196℃的一系列K_(1c)值. 为了说明试验结果的有效性,文中对实验精度进行了分析,并从线弹性断裂力学的基本要求出发,导出了试样的尺寸条件:D≥1.6(K_(1c)/σ_s)~2.最后,通过和标准的三点弯曲试验结果进行对照,二者符合较好。     

三维光弹性实验的“冻结”法

“冻结”法是当前解决三维应力分析问题比较有效的方法,在工程中已获得了广泛的应用。 “冻结”法的实验程序是: 三维模型的应力“冻结”→沿需研究的截面切出薄片→将切片夹持于旋转台上,用偏光弹性仪或偏光显微镜,以平行光法或聚敛光法进行实验量测工作,获得必要的数据——等色线及等倾线→根据实验数据进行应力计算,给出工程中提出的应力分析问题。 应力的“冻结”过程和“冻结”法 目前用的光弹性材料均是高分子聚合物,可以认为它由不可熔和可熔的两种网络组成。在一定温度下,可熔网络的分子链完全崩溃,而不可熔网络仍呈弹性并具有承载…     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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