MD simulation of asymmetric nucleation and motion of 〈011〉 superdislocations in TiAI

The nucleation and propagation of （011] su- perdislocations in intermetallic TiA1 were investigated using molecular dynamics simulations and static energetics calculation, as part of our systematic effort to understand the twining and dislocation behavior of alloys based on y-TiAl. It was found that compared to ordinary dislocations in disordered crystals, superdislocations in ordered TiA1 lattice behave differently when sheared in the two opposite senses along [01-1] direction. This difference is due to the lower Llo lattice symmetry compared with the face-cen- tered cubic （fcc） lattice that it based on, with different yield stress and strain, and dislocation core dissociation and motion. Superdislocations nucleated in the form of loops dissociated in a planar manner into four Shockley partials separated by three kinds of faults： superlattice intrinsic stacking fault （SISF）, anti-phase domain boundary （APB） and complex stacking fault （CSF）, with partial separations depending on the sense of shearing and dislocation char- acter. During loop expansion, the dislocation core changes both in width and dissociation manner depending on the character of the segment in the loop. The core contains four partials close to edge orientation, gradually changing to three fold near 60°, and finally into twofold dissociation around 30° character. Superdislocations may have multiple critical resolved shear stresses （CRSS） for motion depending on dissociation and shearing sense even for the same slip system, with lower critical stress for the motion when SISF is in leading position.     

MD simulation of asymmetric nucleation and motion of h011] superdislocations in TiAl

The nucleation and propagation of h011]superdislocations in intermetallic TiAl were investigated using molecular dynamics simulations and static energetics calculation,as part of our systematic effort to understand the twining and dislocation behavior of alloys based on c-TiAl.It was found that compared to ordinary dislocations in disordered crystals,superdislocations in ordered TiAl lattice behave differently when sheared in the two opposite senses along[0"11]direction.This difference is due to the lower L10lattice symmetry compared with the face-centered cubic(fcc)lattice that it based on,with different yield stress and strain,and dislocation core dissociation and motion.Superdislocations nucleated in the form of loops dissociated in a planar manner into four Shockley partials separated by three kinds of faults:superlattice intrinsic stacking fault(SISF),anti-phase domain boundary(APB)and complex stacking fault(CSF),with partial separations depending on the sense of shearing and dislocation character.During loop expansion,the dislocation core changes both in width and dissociation manner depending on the character of the segment in the loop.The core contains four partials close to edge orientation,gradually changing to three fold near 60°,and finally into twofold dissociationaround 30°character.Superdislocations may have multiple critical resolved shear stresses(CRSS)for motion depending on dissociation and shearing sense even for the same slip system,with lower critical stress for the motion when SISF is in leading position.     

信息不对称、成本与证券评级业的产生

本文从信息经济学及产权经济学的观点出发，对证券评级业产生机理进行了理论分析，认为在需求创造的背后存在着更深的经济学含义———证券评级业是不完全信息条件下，出于对不利选择，道德风险及成本的考虑而产生的。信息不对称和成本是促使它从无到有的核心因素。     

The asymmetric membrane structure of erythrocytes from Crucian carp studied by atomic force microscopy

Cell membranes play a key role in cellular activities. Fish erythrocytes, prototype of the nucleated erythrocytes of lower vertebrates, are predominantly oval, biconvex discs with elliptical nucleus and much larger in size than human erythrocytes. In attempts to disclose the correlation of membrane structure between fish and human erythrocytes, we used in situ atomic force microscope （AFM） combined with single-molecule force spectroscopy to study the membrane structure of Crucian carp erythrocytes under quasi-native conditions. Our results revealed the asymmetric distribution of proteins in Crucian carp erythrocyte membrane： the outer leaflet of membrane is rather smooth without any proteins, whereas the inner leaflet of membrane is very rough with dense proteins. The asymmetry of fish erythrocyte membrane structure fits well with the semi-mosaic model of human erythrocyte membrane structure. This similarity of membrane structure between human and fish erythrocytes extends the semimosaic model of erythrocytes membrane structure to a wider range of species.     

基于数量价格折扣的非对称信息供应链协调

供应链关系中各个经济体与最终市场的接触程度不同,造成各级供应商之间关于市场需求信息的不对称。以S tacke lberg模型为基础,研究短生命周期产品二级供应链的协调问题。设计制造商占主导地位的供应链中基于价格折扣实现信息共享的协调机制。通过比较价格折扣机制协调下各方的收益,证明数量价格折扣不但能促使零售商传递信息,还可以提高供应链整体收益和满足市场需求。上述结论表明通过有效的价格折扣机制可以促进供应链协调、降低零售商市场风险和减少产品短缺现像,有利于整个社会福利的提高。     

基于价格不完全揭示信息资产定价的B股折价

我国B股折价问题作为证券市场分割的异例,受到国内外众多学者的关注.注意到投资者情绪和股票流动性在股价上涨和下跌两个方向的不同作用,本文分别对A股和B股建立了价格不完全揭示信息的理性预期均衡资产定价模型,来研究投资者情绪和噪音交易者行为对B股折价的影响,并通过实证研究对模型结论进行了验证.本文的研究结果表明,A股不知情者的情绪与B股折价正相关,A股噪音交易者行为与B股折价负相关,B股噪音交易者行为与B股折价正相关,同时,由于制度原因造成的系统性差异也是B股折价的一个重要原因.     

试论思想政治教育的“复杂性”——基于协同学的观点

以协同学的视角审视思想政治教育的复杂性,国际形势风云激荡折射出思想政治教育外部环境日益复杂,凸显其对象的异质边缘延展;科技理性的膨胀使得其过程复杂性日益累积,其主体思维惰化僵化;其内部呈现出生成性复杂状态,即教育者、受教育者与教育载体三者间的信息不对称。提出了该复杂性问题的应对机制:提升教育主体的阐释能力,溶解反思性带来的问题;重构教育主体的理性思维,应对非理性带来的问题;确保教育载体信息畅通流动,应对信息不对称所带来的问题。     

现金流波动对企业投资的影响——中国房地产上市公司经验分析

根据现代公司金融理论,在经济转型的制度背景下,以我国房地产行业上市公司为样本,研究现金流波动对投资行为的影响,分别讨论不同产权性质及规模的房地产公司的投资行为差异与动因。实证结果表明,第一,投资关于现金流波动是敏感的,当投资机会与现金流波动共同作用时尤为显著,其中不仅有信息不对称现象还有严重的代理问题;第二,国有企业存在较严重的预算软约束问题;第三,大公司投资对现金流波动更敏感。     

JS型测速管的研究

介绍新颖的ＪＳ型皮托管的研究过程，经实践证明，其性能稳定，测量数据可靠，测孔不易阻塞，适用于各种高温、高压、密封性要求较高的除尘系统中测速。