Phase transition, structure and shape memory effect of Ni47Ti43Hf10 alloy

A Ni47Ti43Hf10 high temperature shape memory alloy is fabricated. The martensitic transformation temperature (TT) is obtained by differential scanning calorimetry and four-probe electrical resistivity measurements. The effect of thermal cycling is investigated and it is found that the TT tends to be stable quickly, which is of benefit to practical applications. The martensite structure is determined to be B19′ monoclinic by X-ray diffraction and transmission electron microscopy. One-way and two-way (which is seldom reported before) shape memory properties are studied by tensile and bending tests. The cycling number of two-way shape memory effect is tested for more than 20000 times.     

基础隔震结构动力可靠度分析及参数优化

假定地震为平稳过滤高斯白噪声过程,基于隔震支座的等效动刚度和等效黏滞阻尼比建立了基础隔震结构的动力方程.针对动力方程中非经典阻尼的情况,采用状态空间理论和复模态叠加法对振动方程进行了解耦,推导了基础隔震体系上部结构和隔震层在随机地震动激励下的方差反应解析式.采用变形准则分别定义了上部结构和隔震层的极限状态,根据首次超越机制,并基于串联可靠度模型建立了隔震结构在给定地震动下的条件动力可靠度计算方法.通过一个基础隔震框架计算实例,说明了该方法的运用.在此基础上,分析了隔震支座等效动刚度和等效黏滞阻尼比对隔震结构随机反应和可靠度的影响,并以失效概率为优化目标,对隔震参数进行优化.该方法可以从整体上对隔震结构可靠性进行评估,为基于可靠度的隔震参数优化提供基础.     

浅析建筑工程人防地下室结构设计

建筑工程地下室的设计是一个综合性很强的问题,涉及内容繁多且复杂,因此无论是从技术还是从经济的角度都需要我们更深入地研究地下室设计的技术问题,提高设计水平,真正做到技术与经济同步、安全与适用协调.文章通过工程实例就建筑地下室设计问题进行了分析.     

体育用人单位对信息技术人才专业技能要求的调查研究

信息技术的飞速发展促进了体育科技的进步,同时也对新时期的体育信息技术人才的素质提出了新的要求。分析信息技术人才的社会需求现状,调研体育用人单位对信息技术人才专业技能的要求,找出毕业生已具有技能与体育领域对信息技术人才技能要求之间的差距,对体育信息技术专业学生的培养具有重要意义。     

洛阳智慧交通系统的地址匹配技术

根据洛阳市城市道路分布的实际情况,研究洛阳智慧交通系统的道路动态段技术、地址数据库结构和数据追加方法、地址数据库和道路数据库的匹配策略.     

Molecular recognition of a single sphingolipid species by a protein's transmembrane domain

Functioning and processing of membrane proteins critically depend on the way their transmembrane segments are embedded in the membrane. Sphingolipids are structural components of membranes and can also act as intracellular second messengers. Not much is known of sphingolipids binding to transmembrane domains (TMDs) of proteins within the hydrophobic bilayer, and how this could affect protein function. Here we show a direct and highly specific interaction of exclusively one sphingomyelin species, SM 18, with the TMD of the COPI machinery protein p24 (ref. 2). Strikingly, the interaction depends on both the headgroup and the backbone of the sphingolipid, and on a signature sequence (VXXTLXXIY) within the TMD. Molecular dynamics simulations show a close interaction of SM 18 with the TMD. We suggest a role of SM 18 in regulating the equilibrium between an inactive monomeric and an active oligomeric state of the p24 protein, which in turn regulates COPI-dependent transport. Bioinformatic analyses predict that the signature sequence represents a conserved sphingolipid-binding cavity in a variety of mammalian membrane proteins. Thus, in addition to a function as second messengers, sphingolipids can act as cofactors to regulate the function of transmembrane proteins. Our discovery of an unprecedented specificity of interaction of a TMD with an individual sphingolipid species adds to our understanding of why biological membranes are assembled from such a large variety of different lipids.     

环向约束条件下高强混凝土早期开裂

为研究环向约束条件下高强混凝土早期开裂趋势,在单面干燥条件下应用非接触式混凝土收缩变形测定仪测试了水灰比为0.26,0.31和0.40试件的早期自由收缩变形.通过静压试验测试了试件早期弹性模量发展,通过改进环向约束试验观测了环向约束条件下各试件内部的收缩应力及应力梯度.结果表明,水灰比越小,单面干燥条件下受约束高强混凝土早期开裂危险性越高,开裂发生时间越早;开裂时间、开裂时弹性模量在很大程度上决定了早期开裂特点.     

价值函数的物理意义

在铀同位素分离领域中，价值函数和分离功率是非常重要的物理量。半个世纪以来，价值函数得到广泛的应用，但其物理意义则未得到明确的解释。本文引入了同位素气体混合物中丰度分布的有序度的概念，并指出价值函数就是正比于同位素气体混合物中丰度分布的有序度的一个物理量，从而给出了价值函数和分离功率的明确的物理意义，并由此出发给出了多元同位素分离过程的价值函数和分离功率的表示式。