HIGH TEMPERATURE LOW CYCLIC FATIGUE BEHAVIOUR OF DIRECTIONALLY SOLIDIFIED Ni-BASE ALLOY DK3

研究了镍基定向凝固高温合金DK3和普通铸造合金K3在760℃应变控制和应力控制下的高温低周疲劳行为。结果表明:这两种合金的高温低周疲劳行为可以用常规的应力疲劳曲线来表征。DK3合金不存在“过渡疲劳寿命”N_T,K3合金则很低。在各种不同应变或应力水平下,DK3合金的低周疲劳寿命高于K3合金,当应力水平为785至980MPa时,其寿命约差1倍,当应力水平为490至685MPa时,则差2倍多。     

贵金属Cu、Ag、Au的电子结构和物理性质

由纯金属单原子理论(OA)确定了面心立方结构(FCC)贵金属Cu、Ag、Au的电子结构依次为[Ar](3dn)5.58(3dc)4.21(4sc)0.23(4sf)0.98、[Kr](4dn)4.87(4dc)4.56(5sc)0.66(5sf)0.91、[Xe](5dn)4.20(5dc)4.90(6sc)1.57(6sf)0.33,并确定了Cu、Ag、Au的密排六方结构(HCP)和体心立方结构(BCC)两种初态特征晶体和初态液体的电子结构。根据自然态的电子结构定性解释了熔点、拉伸强度、维氏硬度、体弹性模量、电导和热导率物理性质差异与电子结构的关系,定量计算了晶格常数、结合能、势能曲线及线热膨胀系数随温度的变化。根据非自然态的电子结构,定性解释了晶体结构BCC和HCP的关系。     

A SIMPLIFIED MODEL FOR NO-STANDARD MICROREGION QUANTITATIVE EDS ANALYSIS OF MULTICOMPONENT ALLOYS

本文对作者建立的微区成分无标样定量分析法进行了简化,使原有的计算量大为减少。 用简化模型对Cu-Si,FeS_2,NaCl,GaAs试样和多元钢样原实验数据进行了定量计算,并与原模型多元程序计算结果进行比较。结果表明,这种简化是合理的。     

AN OBSERVATION OF UNHEALED POROSITIES AND CRYSTALLINE STEPS IN ALUMINIUM ALLOY FORGINGS

铝合金锻件中有时有未锻合的疏松和残留的枝晶自由表面,并保留有原始的结晶台阶。枝晶优先沿<100>方向长大,结晶台阶主要属于{100}及{110}晶面族。 未锻合疏松周围的合金基体有一定变脆倾向,有时可以观察到解理断口。     

尿素合成塔腐蚀情况及原因分析

针对尿素合成塔的腐蚀问题,详细介绍了从投产使用到现在该设备的腐蚀现状.并从不同角度进行详细分析,提出了解决问题的办法及日常运行中应注意的问题.     

对甲醇精馏几个问题的认识

简述甲醇精馏三塔流程原理 ,分析了加压精馏塔及常压精馏塔物料和热量平衡关系 ,提出了操作中应注意的事项     

Change of short-term memory effect in acute ischemic ventricular myocardium: A computational study

The ionic mechanism of change in short-term memory (STM) during acute myocardial ischemia has not been well understood. In this paper, an advanced guinea pig ventricular model developed by Luo and Rudy was used to investigate STM property of ischemic ventricular myocardium. STM response was calculated by testing the time to reach steady-state action potential duration (APD) after an abrupt shortening of basic cycling length (BCL) in the pacing protocol. Electrical restitution curves (RCs), which can simultaneously visualize multiple aspects of APD restitution and STM, were obtained from dynamic and local S1S2 restitution portrait (RP), which consist of a longer interval stimulus (S1) and a shorter interval stimulus (S2). The angle between dynamic RC and local S1S2 RC reflects the amount of STM. Our results indicated that compared with control (normal) condition, time constant of STM response in the ischemic condition decreased significantly. Meanwhile the angle which reflects STM amount is less in ischemic model than that in control model. By tracking the effect of ischemia on intracellular ion concentration and membrane currents, we declared that changes in membrane currents caused by ischemia exert subtle influences on STM; it is only the decline of intracellular calcium concentration that give rise to the most decrement of STM.     

基于轨迹频率抑制的轨迹隐私保护方法

移动终端和定位技术的快速发展带来了轨迹大数据.研究者通过挖掘和分析发布的轨迹数据集,可获得一些有价值的信息.攻击者也可利用所掌握的知识对发布的轨迹数据集进行推理分析,以较高的概率推断出用户的隐私信息.轨迹抑制是一类实现隐私保护的重要方法,然而轨迹抑制的点数越多会造成数据效用越低.因此,在满足用户隐私需求的情况下,如何选择合理的抑制点来提高匿名处理后的数据效用是数据发布中要解决的重要问题.针对以上问题,文中提出两种基于轨迹频率的方案对轨迹数据进行匿名处理.第一种方案是根据情况抑制整条有问题的轨迹数据或向有问题的轨迹数据集中添加假数据;第二种方案是采用特定的轨迹局部抑制法对数据进行抑制处理.实验表明相对于已有方案,在满足同等隐私需求的情况下,文中方案处理后的数据效用提升了近30%.     

Optimizing ranking method using social annotations based on language model

Recent research has shown that more and more web users utilize social annotations to manage and organize their interested resources. Therefore, with the growing popularity of social annotations, it is becoming more and more important to utilize such social annotations to achieve effective web search. However, using a statistical model, there are no previous studies that examine the relationships between queries and social annotations. Motivated by this observation, we use social annotations to re-rank search results. We intend to optimize retrieval ranking method by using the ranking strategy of integrating the query-annotation similarity into query-document similarity. Specifically, we calculate the query-annotation similarity by using a statistical language model, which in a shorter form we call simply a language model. Then the initial search results are re-ranked according to the computational weighted score of the query-document similarity score and the query-annotation similarity score. Experimental results show that the proposed method can improve the NDCG score by 8.13%. We further conduct an empirical evaluation of the method by using a query set including about 300 popular social annotations and constructed phrases. More generally, the optimized results with social annotations based on a language model can be of significant benefit to web search.