热处理对含Y元素AZ31镁合金板材组织和性能的影响

对含Y元素AZ31镁合金板材进行退火处理后的组织和性能进行了研究.结果表明:随着退火温度的升高,镁合金晶粒尺寸逐渐增大,力学性能略有提高然后降低;退火时间对镁合金晶粒尺寸影响不大;在300℃下退火1 h后板材性能达到最佳,抗拉强度为255 MPa,屈服强度为170 MPa,延伸率为24%;经过热处理后镁合金断裂方式为准解理断裂和韧性断裂的复合形式.     

晶界形貌、织构对AZ31镁合金各向异性的影响

采用金相观察、织构分析、拉伸实验等方法,研究了变形工艺、晶界形貌及织构对AZ31镁合金屈服强度及延伸率各向异性的影响.结果表明:轧制过程会使晶粒拉长而产生平直晶界,当拉伸应力方向与平直晶界走向成45°时,AZ31镁合金总是表现出低屈服强度和高延伸率;除了织构之外,晶界形貌也在一定程度上影响着镁合金的力学性能;当拉伸应力与平直晶界走向成0°或90°时,基面滑移的Schmid因子和拉伸孪晶是影响镁合金力学性能的主要因素.     

AZ31镁合金变形行为的热/力模拟

采用GLEEBLE-1500热／力模拟机在变形温度为423～723K,应变速率为0．01～10s^-1,最大变形量为60％的条件下对铸态AZ31镁合金进行热／力模拟研究,并结合热变形后显微组织,分析合金力学性能与显微组织之间的关系。研究结果表明：应变速率和变形温度是影响变形激活能的关键参数;当变形温度一定时,流变应力和应变速率之间呈线性关系,合金的变形激活能在523～573K时变化不大,而在大于573K时增大较快,可用包含Arrheniues项的参数Z描述AZ31镁合金热压缩变形的流变应力行为。     

应力状态对AZ31镁合金最佳成形温度的影响

在20～250℃温度范围内,对AZ31镁合金薄板进行了单向拉伸、筒形件拉深以及胀形试验,并用金相显微镜观察了试验后试件的显微组织。分析了AZ31镁合金在不同工艺所对应的应力状态下塑性变形特点及其最佳成形温度。结果表明,变形过程中所受应力状态对AZ31镁合金最佳成形温度的影响很大,AZ31镁合金在成形过程中受单向拉应力时,其总延伸率随成形温度的升高而增加;应力状态主要为压应力时,最佳成形温度应在tr=1以下;而应力状态主要为双向拉应力时,其最佳成形温度应在tr=1以上。     

AZ31镁合金轧制板材各向异性力学性能研究

在几种厚度的AZ31镁合金轧制板材上沿不同方向取样进行常温单向拉伸和压缩实验,研究了AZ31镁合金轧制板材的各向异性力学性能。基于晶体塑性理论,探讨了织构对金属板材宏观各向异性的影响。分析表明,轧制镁合金板材具有明显的各向异性力学性能及拉压不对称性。在轧制(RD)方向的抗压及抗拉屈服强度明显小于横向(TD),各个方向的抗拉屈服强度明显大于抗压屈服强度。不同轧制工艺对板材的力学性能影响较显著,主要表现在屈服应力不同和延伸率不同。基于实验结果与晶体塑性理论,本文从多角度分析了轧制工艺对AZ31镁合金各向异性力学性能及拉压不对称性行为的影响。     

基于参数优化的人工神经网络的AZ31镁合金力学性能预测模型

通过力学性能试验测定了不同退火条件下AZ31镁合金的抗拉强度、屈服强度和延伸率,并利用人工神经网络技术建立了对应力学性能的预测模型,其中对模型的优化采用了一种新方法,即参数全排列组合训练.结果表明,基于全排列训练得到的最优参数建立的网络模型具有优良的性能,比经传统试探法构建的模型具有更高的平均相关系数和更低的平均误差,因此能更准确地预测AZ31镁合金在不同退火条件后的力学性能.     

双向挤压后AZ31镁合金的微观组织与性能

采用了100T挤压机对AZ31镁合金在不同温度不同挤压比下双向挤压成型。结果表明,挤压比为4.5时,显著地细化镁合金晶粒,晶粒尺寸可由铸态的400μm减小到挤压态的6μm;挤压比为10.125时,晶粒尺寸可以减小到3μm;变形材料的硬度、伸长率、压缩率和屈服强度值有了很大程度的提高,随着挤压温度的升高,硬度、压缩率、伸长率和屈服强度值呈降低趋势(250℃除外)。     

富铈混合稀土对压铸AZ81合金组织和性能的影响

为开发铸造性能优越、成本低廉、中温性能略有改善,并能满足摩托车曲轴箱服役环境的新型镁合金提供材料基础,通过往AZ81合金中添加富铈混合稀土,考查稀土对压铸镁合金AZ81组织和性能影响.结果表明:少量加入稀土能起晶粒细化和固溶强化作用;随加入量增大,稀土以晶界和穿晶条状脆性相存在,对合金强度的损伤作用大于强化作用.因此,压铸AZ81的常温和150℃抗拉强度和屈服强度随稀土加入量的增加先略有提高,然后持续降低;室温延伸率随稀土加入量增加而连续下降,对150℃温度下的延伸率无明显影响;但富铈混合稀土的加入显著提高合金的蠕变抗力.     

热轧AZ31镁合金板材高温塑性变形行为

采用Gleeble-1500热/力模拟系统,研究热轧的AZ31镁合金板材在应变速率0.01,0.1,1,5和10 s-1,变形温度473～723 K,预设最大变形量80%条件下的高温塑性变形行为。采用实验得到的真应力-真应变曲线,分析合金流变应力与应变速率、变形温度之间的关系,计算合金高温变形的材料参数和激活能;用Zener-Hollomon参数法建立合金高温变形的本构关系,并比较实测应力与计算得到的应力。研究结果表明:AZ31镁合金高温变形时受应变速率的影响较大,应变速率小于1 s-1时(573～723 K),合金的真应变接近100%,但当应变速率大于5 s-1时,实验温度范围内合金的真应变都小于60%。AZ31镁合金高温变形的流变应力-应变速率-变形温度的关系可用双曲正弦函数描述,激活能随应变速率和变形温度的提高,从110.4 kJ/mol升高到163.2 kJ/mol。实验获得的AZ31镁合金应力-应变本构方程的计算结果与实验结果较吻合。     

时效对AZ31镁合金组织与性能的影响

对挤压后的AZ31镁合金件进行时效处理。时效温度为200-300℃,时效时间为15min-3h。研究了不同时效温度、时间对AZ31镁合金微观组织、力学性能的影响。结果表明：合适的时效工艺可使挤压变形后的试样组织达到平衡状态,材料塑性有较大幅度提高,而强度并没有显著降低。对于AZ31镁合金,最佳的时效工艺为275℃保温0．5 h。     

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.     

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.     

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.     

A computer generator for randomly layered structures

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

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.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

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.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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