热解炭基1D—C／C力学性能的织构影响及断裂模式

测试了具有不同织构配合的热解炭基１Ｄ－Ｃ／Ｃ的室温单调拉伸σ－ε曲线．结果表明,密度相同时,不同织构配合的材料具有不同的σ－ε曲线．以疏松多孔的粒状炭（Ｇ）为主的材料强度低而假塑性高;各向同性炭（ＩＳＯ）因与炭纤维的界面粘合好而易发生脆性断裂;而含有层间裂纹的粗糙炭（Ｒ）和光滑炭（Ｓ）的影响则居中．热解炭基１Ｄ－Ｃ／Ｃ的拉伸断裂模式主要有台阶型、粗糙型、累积弱化型和整体脱粘型四种类型．前两种为脆性断裂方式,热解炭基体的断裂应变是这类材料强度的控制因素．     

形变氮化20钢拉伸断口和冲击断口的分形研究

本文利用垂直截面法测量了20钢经不同形变和氮化复合处理后拉伸和冲击断裂表面的分形维数．结果表明，材料的拉伸性能（σb、σs、δ）、冲击性能（Ak）和断口表面的分形维数DF均随形变量的增加而增加．冲击断口的分形维数DF与冲击功的对数1nAk之间呈正变化的线性关系．     

高纯铝在范性形变过程中内耗对频率和速率的响应行为

考虑了位错平均速度V=f(σ)随时间或应变的变化之后,导出了金属在范性形变过程中内耗Q～~(-1)与位错动力学关系式V=f(σ),形变速率ε、测量频率ω、测量振幅σ_A 以及切变模量G 等的关系为(?)此处(?)t、(?)p 分别为扭切应力和拉伸应力的平均取向因子,Г(n)为取正值的积分常数,m 为除0,-1以外的整数。可见,形变过程内耗可能出现正比于(ε/ω)~(2/3)、((?)/ω)~(1/2)、((?)/ω)以及((?)/ω)~2等各种对于ω和(?)的响应行为。而且出现随测量振幅σ_A增大而减小的反常振幅效应内耗。高纯铝在拉伸速率(?)=50×10~(-6)/秒时,形变过程内耗Q~(-1)的实验数据与上式中n=-2时的结果符合得很好.此时的内耗可表示为Q~(-1)=0.245(G/σ_A)β_(-2)((?)/ω)~(1/2)/(V_0~′+β_(-2)ε~(-(1/2)).亦即Q~(-1)正比于((?)/ω)~(1/2).还观测到随着σ_A 的增加而减小的反常振幅效应内耗.高纯铝在恒速拉伸时,当ε>0.5%后,位错的平均速度(?)_0。与形变量ε间的关系可表示为(?)_0=V_0~′+βε~(-(1/2));而运动位错的密度ρ可表示为ρ=(?)/ab(V_0~~′+βε~(-(1/2)).     

强紫外线下超高分子量聚乙烯薄板材料的力学性能研究

为了预测和防止高海拔地区超高分子量聚乙烯材料在强紫外线作用下发生老化从而影响工程正常使用和造成严重安全事故,对暴露在室外环境下极容易受到紫外线作用而发生老化的高分子聚乙烯材料进行常温强紫外线人工环境下的老化处理。老化处理后的试样采用扫描透射电镜(EMS)分析其表面微观结构;并用拉伸试验机进行单轴拉伸,分析应力(σ)-应变(ε)曲线、拉伸强度(σ_b)、拉伸弹性模量(E)、断后伸长率(δ_n)及最大力;用ANSYS软件对不考虑温度影响下的试样进行交变荷载条件下的疲劳寿命分析。结果表明:随着强紫外线老化时间增加,应力(σ)-应变(ε)曲线无明显的屈服阶段,拉伸强度、拉伸弹性模量、断后伸长率及最大力的变化是先下降然后逐步趋于稳定,而强紫外线照射时长对疲劳寿命影响不明显。该结果为超高分子量聚乙烯薄板的工程安全应用提供参考。     

两种高强度钢丝低周疲劳寿命的研究

本文采用恒应变幅（△ε）低周疲劳试验方法，测定了高碳Ｐａｔｅｎｔｉｎｇ高强度钢丝和低碳ＬＡＨＳ钢丝的循环应力幅（△σ）和最大应力（σｍａｘ）与循环周次（Ｎ）之间的关系。研究了温形变处理对钢丝低周疲劳寿命的影响。得出，温形变处理可提高低周疲劳寿命３０％～３５％。对这类钢丝的低周疲劳损伤进行了评价。     

冲击载荷作用下复合材料层板动态力学性能的实验研究

介绍了Hopkinson杆冲击拉伸实验设备及其实验技术,对CFRP、GFRP层合板进行了冲击拉伸实验研究,得到不同加载率下CFRP、GFRP层板的应力-应变(σ-ε)曲线,以及断裂强度、拉伸模量和断裂应变随加载速率改变的规律,认识复合材料层板在冲击拉伸情况下动态力学行为和变形、破坏机理。     

压力容器内壁电测应力计算

本文根据弹塑性小变形理论推出压力容器内壁发生塑性变形时电测应力计算公式。得到压力容器内壁周向应力σ_t及经向应力σ_z为: 式中σ_i为应力强度,ε_i为应变强度,σ_i——ε_i曲线可用单向拉伸试验的σ——ε曲线来描述。测出内壁周向应变ε_t及经向应变ε_z可按上式用试差法求出σ_t夏σ_z。对于开式圆筒,因σ_z=0,推得: σ_t=(2σ_i/3ε_i)(ε_t-ε_z) (22)或σ_t=(σ_i/ε_i)ε_t-(P/2) (26)上二式中σ_i=(σ_t~2+σ_tP+P~2)(1/2) (23)按式(22)或式(26)用试差法可求得开式圆筒内壁周向应力σ_t。     

热致形状记忆环氧乙烷—对苯二甲酸乙二酯多嵌段共聚物

不同软链段长度和不同硬链段含量的环氧乙烷－对苯二甲酸乙二酯被合成．分别测试了它们的拉伸样条的热致形变恢复．Ｓ形热致形变恢复曲线用最大形变恢复率（Ｒｆ），形变恢复温度（Ｔｒ）和形变恢复速度（Ｖｒ）表征．这些量的数值结果表明软链段的结晶状况决定热致形变恢复温度，最大形变恢复和形变恢复速度既依赖于硬链段所形成的物理交联点的稳定性，也受软链段长度变化的影响．后一影响是形变恢复的熵本质决定的     

钨合金的冲击拉伸行为及其本构和断裂判据的表述

利用飞轮式Hopkinson拉杆实验技术对钨质量分数为93% 的钨合金在-50～100℃温度范围、应变率ε=102～10３s-1区间的动态拉伸性态进行了测试，提供了相应的σ-ε曲线和最大拉伸失效应变，并以此为依据建立了该合金动态拉伸行为的本构关系，提出了该合金受动载发生塑性失稳以致发生拉断的判据。利用断口分形分析理论，对试件拉伸断口微观特征所作的分析和对宏观力学性态实验所作的结论给予了有力的支持。     

SCM435钢热变形动态再结晶动力学模型参数的确定

通过分析冷镦钢SCM435在温度为950～1150℃、应变速率为0.1～1s-1范围内发生动态再结晶的热/力模拟试验数据,利用其应变硬化速率θ与流变应力σ的θ-σ曲线,准确确定了其发生动态再结晶的临界应变εc、峰值应变εp、临界应力σc和峰值应力σp,用应力-应变(σ-ε)曲线方法计算SCM435钢的动态再结晶Avrami动力学曲线和时间指数n.结果表明:SCM435钢发生动态再结晶的临界应变与峰值应变的平均比值εc/εp=0.73,动态再结晶Avrami时间指数平均值n=1,91;在温度950～1150℃,应变速率0.1～1 s-1范围内,应变速率是SCM435钢的动态再结晶动力学敏感因素,温度对其影响不大;动态再结晶率50%的时间t50与应变速率成反比.     

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