基于颈椎动力学响应的座椅被动安全性研究

为研究汽车后碰撞中不同的座椅靠背结构对颈部损伤的影响,基于人体解剖学和实际座椅测量数据构建了人–座椅系统有限元模型.通过后碰撞仿真模拟,得到采用不同座椅靠背时人体颈椎的应力应变响应数据,以此数据为依据进行对比分析,找出了发生事故时对汽车乘员保护性能较好的一款座椅靠背骨架结构,或可为座椅的被动安全性设计提供一种行之有效的新思路.     

保护后排乘员安全的前排座椅参数研究

在汽车发生正面碰撞时,后排乘员由于惯性向前移动,十分容易与前排座椅发生二次碰撞而造成伤害。为了在轿车正碰时减小后排乘员与前排座椅发生碰撞时造成的损伤,本文提出一种基于前排座椅参数的优化方法。以提高正面碰撞中轿车后排乘员安全性为目标,根据2012年版中国新车评价规程[C-NCAP管理规则(2012年版)]的要求,以后排5百分位女性假人为研究对象,研究两排座轿车前排座椅参数对后排乘员的防护效果。在MADYMO软件中建立轿车后排乘员正碰数学模型,并用实车试验进行验证,在此基础上,分析了前排座椅头枕参数中的头枕水平距离和头枕刚度,以及前排座椅靠背参数中的靠背刚度、靠背距离、靠背倾角和靠背坐垫连接铰刚度这6个主要因素对后排乘员保护效果的影响。采用灵敏度分析的方法探寻对于后排乘员安全性影响最为显著的因素,并使用正交试验的理论,对这几项因素进行综合优化,得到最佳匹配方案。优化设计结果使正面碰撞时后排乘员伤害最严重的头部伤害值HIC降低了25.26%,左大腿力和右大腿力分别下降了13.67%和14.33%,完全伤害指标WIC值降低17.91%,优化效果显著,可以为今后轿车前排座椅设计提供参考。     

面向提升学生创新实践能力的汽车座椅试验台开发

具备创新实践能力是机械类学生必须具备的学习素质,该项研究以汽车试验台开发为载体,全面提升学生的专业水平与创新实践能力。通过分析各个国家关于车辆座椅、座椅固定装置及头枕认证法规试验方法和性能要求,开发了座椅靠背及头枕静强度和刚度试验台,以实现座椅强度和刚度的自动检测。试验台主要包括机械系统、液压系统、控制系统共3部分。通过实验测试及结果分析,验证了所开发实验台的有效性。结果表明,该试验台能够比较准确地满足座椅性能的实际测试需求。     

桁架结构强度计算研究

分别采用轴力杆单元、弯曲-轴力梁单元和三维实体单元的有限元法对桁架结构进行静力分析.计算结果表明:采用轴力杆单元和采用梁单元的轴向应力接近,采用实体单元节点处的最大等效应力远高于杆单元模型和梁单元模型的应力,采用实体模型的位移大于杆单元和梁单元的位移;理想桁架中应力为零的杆件,用梁单元和实体单元计算应力并不为零;桁杆两端和节点存在应力集中,等效应力数值远大于杆件的应力.理想桁架的计算方法的杆件轴向应力虽然计算精度较高,但是不能反映节点的应力集中,桁架的强度计算应该考虑节点的应力集中.文中研究结果可以用于井架及电塔结构的强度设计.     

大口径闸阀阀体强度分析与结构优化

利用有限元软件对楔式闸阀阀体强度进行计算和分析,找出应力集中点,以应力集中处的最大等效应力作为目标函数,以阀座凸台处基本尺寸作为设计变量进行优化设计.得到理论最优的结构尺寸,提高阀体的强度,使阀体的应力分布更加均匀.优化前后结果对比表明优化后的阀体最大等效应力减少16.7%,优化后的阀体性能得到较大改善.     

子模型技术在精轧机机架强度分析中的应用

采用有限元方法对热轧精轧机机架进行应力分析.通过子模型技术对机架上横梁压下螺母孔顶部过渡圆弧处应力最大的部位进行精确计算,比较了整体模型和子模型计算结果差异,结果表明子模型方法更适合于机架应力集中处强度分析的精确计算.     

基于Optistruct的地铁车顶骨架有限元强度分析及优化

为了对某新型地铁车顶骨架结构进行优化,在十二个工况下对其进行了结构静强度分析,根据各工况的应力分布情况,找出了应力集中的位置并分析其产生的原因,利用OptiStruc优化工具提出了六种优化方案,根据优化尺寸再次进行强度分析,分析结果显示方案一车架骨架在满足应力的要求下,整体结构挠度最小.通过对车顶骨架优化的应力对比,表明提出的优化方案是可行性的.     

考虑应力集中的吊车梁多轴疲劳寿命预测

钢结构吊车梁在工业建筑中被广泛应用,应力集中的存在导致几何不连续位置在复杂应力下服役.借助有限元法分析吊车梁应力-应变状态,确定危险点位置,并提取应力、应变分量;以应变能密度作为损伤参量并以最大平面为临界面,基于能量准则建立临界面位置数值计算方法,结合有限元结果给出吊车梁临界面位置;考虑吊车梁在非对称载荷下服役,借助Goodman方程进行平均应力修正,并结合Q355D钢近似S-N曲线计算疲劳寿命.该方法考虑了应力集中处多轴应力对疲劳损伤的影响,可以为复杂应力下几何不连续钢构件的疲劳寿命评估提供新方法.     

高温高压对冶金用热水循环泵结构强度的影响

为获得冶金用热水循环泵实际工作状态下的结构强度,对泵内部全流场进行了多工况定常数值模拟,并基于ANSYS Workbench平台对泵转动部件与静止部件进行了单向流固耦合计算.得到了不同工况下关键零件的最大等效应力,并对比了常温常压与高温高压条件下转动部件与静止部件的应力分布,分析了结构应力分布特征.结果表明:热水循环泵各零件最大等效应力值均小于自身材料的抗拉强度,满足强度要求;常温常压条件下,转动部件的键及键槽处应力值最大,而在高温高压条件下,泵轴轴承段因热载荷出现了应力集中的现象;常温常压条件下,泵体应力分布主要受到重力作用,各支撑部位的应力较大,高温高压条件下,泵体温度梯度较大位置应力较大.     

高速磁悬浮列车悬浮架结构可靠性研究

针对高速磁悬浮列车悬浮架结构可靠性评估问题,利用Hypermesh软件建立悬浮架的有限元模型,根据悬浮架实际运行情况,提出一套约束方案,并利用Ansys软件对高速磁浮列车进行静强度、疲劳强度以及模态分析,分别基于von Mises应力、Goodman疲劳极限图评估悬浮架结构的静强度和疲劳强度,基于Block Lanczos法计算悬浮架模态.结果表明:悬浮架的静强度分析结果显示4种超常载荷下最大受力位置均出现在摆杆处,总体均满足静强度要求;疲劳强度分析结果显示悬浮架上关键点应力和应力幅均在材料修正的Goodman疲劳极限内,满足疲劳强度要求;模态分析结果显示悬浮架的自振频率明显高于激振频率,不会产生共振现象,满足车辆运行要求.     

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