电磁铸轧铸嘴支撑面板温度场及热应力研究

铸嘴支撑面板为电磁铸轧工艺的关键部件，其结构稳定性直接关联到铸嘴的平面稳定性。本文利用ANSYS有限元分析软件建立了铸嘴支撑面板温度－应力耦合分析的三维有限元计算模型，并对实际工况下面板的热应力分布进行了计算研究。研究结果表明：面板内存在显著的热应力，应力集中现象明显；面板总体上出现了较大的热位移，特别是在竖直方向，热位移量为最大，导致面板因变形过大失效，计算值与实测值相吻合。     

冷中子源低温真空冷箱应力场分析及结构设计

为了减小真空冷箱在低温工作状态下受到的大气压力、设备重力以及内部管道因降温收缩而产生的热应力的复合作用，运用ANSYS有限元分析软件模拟冷箱和管道的应力场及变形．结果表明：管道的热应力随管道直径、相对弯曲度的增大而增大；冷箱最大变形发生在上法兰中间区域，应力集中在冷箱壁与加强筋相交区域．根据计算的结果，针对性地提出了适当减小管道直径和相对弯曲度以及增设加强筋和加固壁的改进方案．改进后的计算结果表明，冷箱的最大变形值由9．7mm减小到1．3mm，应力和变形分布趋于平缓，达到了优化设计的效果．本研究为冷中子源氨制冷系统的设计，提高系统工作的稳定性和可靠性提供了技术参考．     

考虑进气效应和非线性接触的活塞瞬态应力研究

针对经验公式计算活塞顶面传热边界不准确和热应力计算中引入位移约束产生人为应力集中的问题,采用燃烧模拟和有限元方法构建非线性接触对,研究活塞瞬态应力。首先,燃烧模拟仿真得到活塞顶面传热边界条件,并实现向有限元模型的瞬态映射;然后,用非线性接触模拟热和力在构件间的传递,对比有、无进气冷却效应下的活塞瞬态温度场,结合测温试验进行温度场验证,对比有、无非线性接触的活塞热应力场;最后,结合机械负荷,进行在交变热-机械负荷作用下的活塞瞬态应力场分析。计算结果表明:采用燃烧模拟和有限元方法进行活塞瞬态温度场研究,能更准确地反映活塞顶面温度在时间上的波动和空间上的不均匀;非线性接触改善了施加位移约束产生的人为热应力集中问题,对比排气侧,活塞进气侧的热应力高出11.9%;热机耦合应力不是热应力和机械应力的简单叠加,且热、机械应力有一定程度的相互抵消。     

深部巷道围岩热-固耦合条件下的变形破坏数值分析

为研究深部巷道围岩热-固耦合条件下的变形破坏特征,根据深部巷道围岩体稳态温度场模型,得出了热-固耦合条件下深部巷道围岩体应力场、位移场及塑性圈半径的解析解,总结了热应力作用下围岩变形破坏的影响因素。借助Comsol Multiphysics多物理场耦合仿真软件对深部巷道围岩进行热-固耦合数值模拟,并将岩石力学参数与温度的关系引入模拟计算,分析了热应力、支护阻力对围岩变形破坏的影响规律。仿真结果显示,围岩热应力场分布呈非线性变化,浅部应力梯度大,深部应力梯度小;当巷内温度低于原岩温度时,热应力为压应力;随原岩温度升高,径向卸压范围及切向应力集中范围扩大,围岩塑性圈宽度和径向位移值有所增大;随巷内支护阻力提高,围岩塑性圈宽度和径向位移值则有所减小。现场试验发现,巷道围岩热应力场、应力场及位移场计算结果与实测结果吻合较好。     

套管-水泥环-地层耦合系统热应力理论解

根据弹性力学和热力学理论,推导了套管-水泥环-地层耦合系统的热应力和热位移理论计算公式,分析了系统热应力和热位移径向分布规律,以及套管温升、弹性模量、热膨胀系数、壁厚、水泥环与地层弹性模量和泊松比等参数对套管热应力和热位移的影响.结果表明:随着离套管中心径向距离的增加,径向热位移和热应力先增大后减小,最大值分别位于地层和套管外壁,而套管上Von Mises应力值迅速下降,最大值位于套管内壁;随着套管温升和套管、水泥环、地层弹性模量与热膨胀系数的增加,套管内壁Von Mises应力和外壁径向压力增大,其中套管参数变化对计算结果影响更明显.在进行稠油热采井套管抗挤毁强度计算时,应考虑热膨胀在套管外壁产生的径向压应力的影响.     

网眼多孔陶瓷中缺陷形成的有限元分析

根据有机泡沫模板孔筋实际结构，设计了合理的模型，采用有限单元法对脱胶过程中的热应力进行了计算．计算结果表明：凹三角形的棱角处最易破坏，随着涂覆厚度的增加，热应力逐渐减小，这样就可以减小热应力对涂覆层的破坏，提高材料的力学性能．在有限元分析的基础上，采用改进的两次离心挂浆工艺制备了网眼多孔陶瓷，增加了模板的涂覆厚度，材料的力学性能得到了显著提高．实验结果与理论计算相吻合，有力证明了有限元计算结果的正确性及其对工艺改进的重要指导意义．     

导流槽阴极热应力分布计算和结构优化

使用ANSYS有限元计算软件建立了75 kA导流型铝电解槽热应力分布的计算模型,对聚铝沟位于槽中部导流型铝电解槽阴极内部的热应力分布进行了计算研究,为了减小阴极内部应力的集中,对电解槽结构进行优化.研究结果表明:采用典型的截面为矩形的聚铝沟和普通方钢作为阴极钢棒时,在聚铝沟处的阴极炭块和涂层以及阴极炭块内部炭糊与阴极钢棒端部接触之处存在较大的应力集中,从而可能造成阴极炭块开裂以及涂层与阴极炭块分离;采用半圆形截面聚铝沟能缓解角部的应力集中,但在聚铝沟圆弧底部的炭块和涂层中各存在1个x方向的正应力集中,最大值分别为-6.65×107Pa和-4.97×107Pa;采用小直径圆弧角的聚铝沟要比采用半圆形或矩形截面的聚铝沟更能改善此处涂层和炭块中的应力分布,而采用端部为半球形的阴极钢棒能有效地减小阴极炭块内部由于阴极钢棒热膨胀产生的应力集中.     

基于有限元方法的锅炉汽包应力在线监测程序的研究

为了监测汽包下降管接头处的应力，利用当量管接头模型，将汽包下降管接头的三维结构简化为二维结构，用有限元方法编制了汽包应力分布的在线监测程序，并在电站仿真机中进行了应用．针对电站仿真机与实际参比机组在系统及显示参数方面相一致的特点，利用仿真机的运行参数对汽包在锅炉热态启动过程中应力随时间的变化和应力分布进行了仿真研究．结果表明，该程序可以实现汽包应力在线监测的功能，并能满足工程需要．为了减小汽包寿命的损耗，建议在锅炉启动过程中合理地投入燃料量，以控制汽包的升温速度，尽可能减小汽包的热应力；在运行中应尽可能维持压力的稳定，以减小汽包机械应力的变化．     

椭圆孔对俘获场超导体应力分布的影响

根据高温超导体受电磁力作用的受力机制,研究了具有中心椭圆孔的超导体内应力和位移的分布.利用了Bean临界态模型和有限元方法,首先讨论了中心椭圆孔长短轴之比对超导体内应力和位移分布的影响,继而分析了不同磁场条件对超导体内应力和位移分布的影响.结果表明:由于应力集中的影响,随着椭圆孔长短轴之比的增大,超导体内径向应力和环向应力只在孔附近显著增大,而位移变化都很小;随着外磁场的减小,径向应力和位移的最大值先增大后减小,而环向应力的最大值不断增大.     

水平连铸坯热应力的计算和分析

应用铸坯凝固过程中的热弹塑性应力模型,对马钢水平连铸热试期间的铸坯进行了传热、应力和应变分析计算。定量地反映了铸坯的热应力分布,指出水平连铸铸坯出结晶器后,表面温度回升太大,可能产生中间裂纹和中心裂纹。     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-