火车电机轴锁紧螺母及止动垫失效分析

对火车电机轴锁紧部件早期失效原因进行了分析研究。分析了失效构件的成分、性能、宏观及微观断口形貌和显微组织。由此得到：构件失效的主要原因是：锁紧螺母的热处理工艺不当，止动垫电镀过程发生氢脆。同时提出了预防措施。     

基于全周期分段步加的极小子样加速实验方法

针对滚动功能部件在其使用过程中的磨损失效等将直接影响其服役性能的问题,为方便高效地获得滚动功能部件不同时间历程下的在线监测和离线状态数据,提出了一种基于全周期分段步加策略的极小子样滚动功能部件加速实验方法.将滚动功能部件沿轴线方向分成n+1个子段,从子段1开始在加载力Fi作用下以速度vi自子段i至子段n往复跑合zi次,建立了各分段的等效加载力、等效跑合速度、第i个子段单位长度上正常应力水平下总的服役时间Ti的计算模型,并搭建了滚动功能部件服役性能加速实验台.该加速实验方法可应用于细长轴类零件的服役性能和失效演变机理分析及其寿命和可靠性的预测评估.     

基于多值决策图的多状态线性consecutive-k-out-of-n系统的性能分析

多状态线性consecutive-k-out-of-n系统(简称MLC(k,n)系统)是由n个部件按顺序串联排列在一条线上组成的.MLC(k,n)系统根据连续失效部件的数量不同,呈现不同的性能.基于多值决策图(multi-valued decision diagram,MDD),提出一种MLC(k,n)系统性能分析方法 ,对具有任意寿命分布异构部件的MLC(k,n)系统的性能进行建模和评估,重点给出了高效的MDD模型生成算法.通过分别对不可修复和可修复MLC(k,10)系统的具体实例分析,说明了MDD方法的有效性,其适用于任意寿命分布的异构不可修复部件系统.     

基于性能退化的刀具可靠性评估

针对长寿命少失效样本条件下的可靠性评估问题,从性能退化角度分析了退化指标分布已知与未知条件下的性能退化路径的可靠度评估方法.以刀具为例,将其加工过程的刀具磨损量作为退化指标,建立了3种不同的退化路径模型,结合失效阈值,准确地估计出了刀具的伪失效寿命,并通过伪失效寿命数据分布模型进行了刀具的可靠性评估,对比分析了3种分布模型的可靠性指标差异,验证了该方法的有效性,为长寿命少失效样本条件下的设备可靠性评估提供了新的方法和思路.     

竞争失效下多元退化建模的航空发动机可靠性分析

为了解决航空发动机的竞争失效下多元退化系统可靠性评估问题,提出一种多元退化失效和突发失效之间相关竞争失效的可靠性评估方法.以具有随机效应的非线性Wiener过程与Gamma过程描述退化失效过程,选择合适的Copula函数对多元退化失效相关性进行建模,通过马尔科夫链蒙特卡洛方法进行多元退化系统相关失效模型参数估计;引入Weibull分布描述突发失效时间,采用比例危险模型构建关于性能退化量的突发失效率函数,利用两步极大似然估计法识别模型参数.结合航空发动机的性能退化数据实现了竞争失效下多元退化系统可靠性评估,通过分析结果验证了模型的有效性与准确性.     

星载遥感仪器扫描部件可靠性验证试验

高可靠扫描部件是星载遥感仪器的关键部件,其可靠性验证试验的试验样本具有"小子样、零失效"的局限.工程中迫切需要制定合理可行的验证试验方案,在有限的试验周期内验证产品的可靠性是否符合指标要求.利用可靠度R(t)的验前信息,基于Bayes方法推导出了"小子样、零失效"情况下可靠性验证试验试验时间的算法;并给出了算例.结果表明,与传统算法相比在指标和样本量相同的情况下,新方法可减少试验时间,降低试验成本.     

连铸结晶器铜板表面镀层失效分析

结晶器是连铸技术过程中非常重要的组成部件.结晶器铜板长时间经受钢水冲刷,必须具有很高的耐摩擦磨损、耐腐蚀性能.结晶器铜板常见的失效形式有裂纹、腐蚀等,本文结合案例研究和分析了结晶器铜板的主要失效形式及其原因.     

复杂多态系统的区间值模糊贝叶斯网络建模与分析

随着现代工程系统结构复杂度的增加以及运行环境的复杂化,传统的可靠性分析与评估技术已不能满足现代工程系统需求.针对复杂多态系统可靠性分析与评估的需求,本文从部件状态分析、系统结构分析入手,对存在认知不确定性同时考虑失效相关性的复杂多态系统进行可靠性建模与分析.由于现代复杂多态系统信息输入及系统故障影响因素的多样性,以及系统冗余,使得不确定性和共因失效对复杂多态系统可靠性分析和评估至关重要.本文借助贝叶斯网络对多态系统的图形表达和推理优势,采用模糊理论中区间值三角模糊数对部件概率进行描述;同时利用β因子模型对共因失效进行量化,再将其以新增共因节点的方式实现共因失效的贝叶斯网络建模,从而提出基于区间值模糊贝叶斯网络的复杂多态系统可靠性分析方法.最后,将基于区间值模糊多态贝叶斯网络对具有共因失效的多态卫星天线双轴定位机构传动系统进行可靠性分析.通过对实际工程系统的分析,表明本文建立的多种因素影响下复杂多态系统的可靠性建模和分析方法,进一步完善了复杂系统可靠性分析理论与方法.     

基于时域分析法的牵引电机风机轴承性能评估

为防止动车组牵引电机过热损坏,需配备通风机为牵引电机提供冷却风源,而风机上的滚动轴承是导致冷却风机损坏的主要部件,因此需要研究牵引电机风机轴承的退化性能评估问题。利用时域分析法去评估动车组五级修更换下来的风机轴承的性能,并提出一种将加速度有效值、峭度值两个时域指标结合在一起联合判断风机轴承运行状态的方法,该方法创新之处在于将风机轴承整个寿命周期划分为正常期、衰退期、失效期三个阶段,研究出滚动轴承在不同阶段的性能评估适用于不同的时域参数指标。     

波音737飞机自动刹车系统研究

本文介绍了波音737飞机自动刹车系统的控制原理,分别对系统正常工作和失效时的条件进行了分析。自动刹车系统失效的典型故障涉及众多部件,逻辑关系复杂。总结了系统故障的主要原因和排故经验,对可能失效的部件及相关控制逻辑进行了研究。     

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