圆端形钢管混凝土双向偏压柱的力学性能研究

在合理确定钢和混凝土本构模型基础上,运用有限元数值分析软件ABAQUS模拟典型圆端形钢管混凝土双向偏压柱的荷载-变形曲线,开展工作机理分析. 分析结果显示： 在双向偏压荷载作用下,圆端形钢管混凝土柱能表现出较高的极限承载力和延性;钢管对核心混凝土可起到有效约束作用,圆弧段钢管对混凝土的约束效应高于平直段钢管. 典型算例表明,圆端形钢管混凝土双向偏压柱的M_x/M_ux-M_y/M_uy相关曲线呈四分之一椭圆形. 最后提出该类双向偏压柱承载力的简化计算式,与有限元模拟结果对比,简化计算结果偏于保守.     

内爆爆距对舱壁变形影响的数值研究

为研究舱内爆炸时爆距的改变对舱壁的毁伤效应,运用有限元分析软件建立了舱室内爆的仿真模型,分析了爆距变化对舱壁的变形影响及舱内冲击波压力的作用情况.结果表明：在爆距比L₁/L₂>1时,远端舱壁的变形挠度总大于近端舱壁.当爆距L₁增大时,远端舱壁的挠度值呈线性增加,挠度增量约为爆距增量的11%,而近端舱壁的挠度变化不明显;舱内爆炸后作用于远端舱壁的冲击波为初始冲击波与来自近端舱壁及四周刚性舱壁的反射冲击波相互作用而形成的叠加波.     

爆炸作用下预应力混凝土节段箱梁动力响应

为了研究爆炸冲击作用下预应力混凝土多室箱梁的破坏机理和抗爆性能，针对不同炸药当量和爆炸位置下节段箱梁的动力响应进行了有限元计算分析。利用ANSYS/LS-DYNA软件建立混凝土和钢筋三维分离式实体模型；采用LOAD＿BLAST＿ENHANCED(LBE)方法模拟爆炸荷载，并结合文献试验数据对数值模拟方法的可靠性进行验证。得到了不同装药量、爆炸位置工况下预应力混凝土箱梁的动力响应和破坏特征。结果表明，100 kg、500 kg药量爆炸作用下，爆心正下方的钢筋发生屈服、顶板混凝土形成圆形破口。1 000 kg药量爆炸作用下，由于箱梁两端为固支，腹板、横隔梁及底板混凝土产生了轻微的剥落。相同爆炸位置工况下，随着装药量的增大，混凝土圆形破口面积增大。相同药量工况下，主梁中心线处由于无腹板支撑，其混凝土破口面积大于箱室处。研究结果可为预应力混凝土多室箱梁的抗爆防护加固提供重要参考。     

弱CM环的性质

主要研究特殊Noether交换环弱CM环的性质.这类环包括Cohen-Macaulay环、优秀环和广义Cohen-Macaulay环,能够用局部上同调模来刻画.证明了如果R是弱CM环,则R的有限生成代数, 以及R关于理想I的I-adic完备化环均为弱CM环.     

高强钢筋高强混凝土预应力梁抗弯性能试验研究

通过对12根高强钢筋高强混凝土预应力梁的抗弯试验,观测试验梁的破坏现象和失效过程,研究混凝土强度等级、非预应力高强钢筋配筋率、预应力钢筋配筋率等因素对其抗弯性能的影响规律.试验结果表明,高强钢筋高强混凝土预应力适筋梁破坏过程包括开裂前阶段、带裂缝工作阶段和钢筋屈服后直至失效3个阶段,各阶段破坏模式与普通钢筋混凝土梁受弯破坏相似,均为延性破坏.混凝土强度等级以影响钢筋屈服后的抗弯性能为主,高强度等级混凝土试验梁的后期承载力下降较小.非预应力筋配筋率显著影响试验梁开裂后的抗弯性能,即相同变形时,配筋率越高承载力越高.相同张拉控制应力条件下,预应力筋配筋率越高开裂弯矩越大;相同弯矩作用下,预应力配筋率越高变形越小,其极限承载力也越高.     

在役预应力混凝土箱梁开裂后承载力评估

针对目前大量存在的在役预应力混凝土箱梁桥跨中下挠和开裂的现象,基于主要受力裂缝的外观统计特征,通过构造两类损伤单元,即正裂缝区损伤单元和斜裂缝区损伤单元,采用刚度折减和引入平面刚架模型的方法,建立了基于裂缝统计特征参数的损伤预应力混凝土箱梁计算模型,提出了基于截面刚度变化的预应力混凝土箱梁桥截面有效刚度折减系数和基于混凝土受压区应力变化程度的承载力折减系数,从而实现了对在役预应力混凝土结构开裂损伤后,在其使用过程中的受力性能评价.     

火灾下高强钢栓焊连接节点力学性能数值研究

采用ABAQUS对高强钢栓焊连接节点火灾下的力学性能进行模拟,通过经验证的模型对高强钢栓焊连接节点进行参数分析。结果表明：温度升高,节点的极限抗弯承载力M_max、节点塑性抗弯承载力M_y和节点的初始刚度K_ini均降低;强度较低钢材的节点匹配较厚的梁柱翼缘和腹板比强度较高钢材的节点匹配较薄的梁柱翼缘和腹板,可获得相近的节点塑性抗弯承载力以及相近或更高的节点转动能力,从而实现节点优化设计。     

2009～2010年大华北岩石圈磁异常分布及其变化特征

 使用曲面样条和球冠谐和方法,对2009年和2010年所测量的2期大华北地区218个地磁场测点的数据所描述的岩石圈磁场F,D,I3个要素进行分析.2期测量所得到的F,D,I3要素的宏观分布类似.D要素的值在华北东北部负值增强、正值减弱,在华北的中西部负值减弱、正值增强;在整个华北的大部分地区,F要素的负异常减弱,正异常增强,江苏滨海和辽冀附近的正异常减弱,负异常增强;I要素在华北大部分地区正值增强负值减弱,在辽宁东北部,山西东边界至晋豫交界附近的区域正值减弱负值增强.     

隔爆墙后爆炸冲击波绕射与超压分布规律

基于爆炸实验与数值模拟,对爆炸载荷作用下隔爆墙后的冲击波绕射和超压分布规律进行了研究.首先,开展了隔爆墙对爆炸冲击波隔离效应的实验,得到了有/无隔爆墙条件下相同爆距处的冲击波超压时程曲线.在此基础上,采用流体动力学软件AUTODYN对爆炸冲击波的绕射过程进行了数值仿真,通过与实验结果的对比验证了模型的有效性.结合数值模拟和量纲分析,得到了不同爆炸当量、爆距、墙高等参数下隔爆墙后不同区域的冲击波超压分布规律,并给出了隔爆墙后近地面超压峰值的工程计算公式,为隔爆墙的设计和安全评估提供了依据.      

大直径高强预应力筋混凝土梁承载能力数值分析

目的研究大直径高强钢绞线预应力混凝土梁受力性能,进一步扩展大直径高强预应力筋在实际工程中的应用范围.方法以直径为17.8 mm的1860级钢绞线作为预应力筋,普通钢筋作为非预应力筋,设计制作了6根大直径高强钢绞线预应力混凝土简支梁.试验梁进行三分点加载试验,基于相关试验数据和数值分析方法,对大直径高强钢绞线预应力混凝土梁进行受弯承载力非线性研究,探讨预应力筋配筋率、非预应力配筋率、预应力筋强度指标和混凝土强度等级等参数对模拟梁构件承载力影响规律.结果预应力筋配筋率的提高即能够明显改善预应力混凝土梁构件变形性能,又能提高梁构件承载能力;混凝土强度等级与非预应力配筋率是影响梁构件受弯承载力的重要因素.结论通过对大直径高强预应力筋混凝土梁构件的参数分析,为工程实践提供依据的同时,也为其更广泛的技术应用提供设计参考.     

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