钛酸锶基粉体功能材料的合成与应用研究进展

钛酸锶作为一种典型的钙钛矿型结构物质,具有介电损耗低、热稳定性好和光催化性能优良等特点,是一种用途广泛的功能陶瓷材料。综述了近年来以钛酸锶为基体各种功能陶瓷材料的合成方法与重要应用,并探讨了其今后的主要发展方向。     

A Method for Automatically Establishing a Mathematical Model of Kinematic Analysis to a Planar Mechanism with a Multiple Joint and Prismatic Pair

A method for automatically establishing a mathematical model of kinematic analysis to a planar mechanism with multiple joint and prismatic pair is presented.The breadth(or depth) first search spanning tree can be obtained based on an adjacency matrix of the mechanism.Then the kinematic chain(or mechanism)’s basic loops can be obtained.On the basis of these basic loops,a mathematical model of kinematic analysis can be established and solved automatically.In the sense of a calculative mechanism,structural analysis of the kinematic chain relates to the kinematic analysis of a mechanism.Thus,an effective way is supplied to the given mechanism’s kinematic analysis for automatic modeling and solving,and a method is supplied to the structural type to optimize kinematic synthesis.     

HDDR工艺条件及均匀化处理对Nd12.6Fe69.3Co11.6 B6.0 Al0.5合金磁性能的影响

研究了HDDR工艺条件(包括HD温度、HD时间、DR温度、DR时间)对Nd12.6Fe69．3Co11.6B6．0Al0．5合金磁性能的影响；比较了均匀化处理和未均匀化处理的合金经HDDR工艺后磁性能的差异；通过对两种舍金原始态的XRD谱线分析，找出存在差异的原因。     

Analysis of non-loading carrying fillet welds joint using SGBEM

Fatigue failure is probably the most common type of failure in welded construction. It is usually initiates at a stress concentration area within the structure. The fatigue behavior of non-load carrying cruciform fillet welded joint has been studied extensively using boundary element method. The symmetric boundary element method for multiple cracks problem is derived using Betti's reciprocal theorem in auxiliary fictitious state. High order element is proposed to solve the double integrals. The analysis demonstrates that symmetrical Galerkin boundary element method (SGBEM) can be used effectively for analyzing non-load carrying fillet welded cruciform joints containing any number of surface and embedded cracks. The stress intensity factor and the magnification factors M _k are analyzed. General formulation for this kind of fatigue life estimation is derived for engineering design purpose. The fatigue life estimate results are consistent with the code of practice and those of other researchers. This can provide a good method for engineering design under fatigue loading conditions.     

对一个群签名方案的分析与改进

分析了一个基于中国剩余定理的群签名方案,指出此方案并不安全：任何一个群成员或已被撤销的群成员都可以完全攻破此方案。针对该安全缺陷提出了一个改进的新方案。分析表明,该方案不仅可以在不改变其他群成员密钥的情况下有效地增加和撤销群成员,而且具有不可伪造性、防陷害攻击、抗联合攻击等性质。     

数据缺失下学习贝叶斯网的SEM算法

针对SEM算法易收敛于局部最优的问题,提出一种改进SEM算法——DSEM-PACOB算法,采用PACOB算法提供的良好候选网络及合理的策略,估计节点变量缺失值,并使与待估节点变量紧密相关的若干节点变量直接参与估计。实验结果表明,与SEM算法相比,利用新算法获得的最终解的质量有所提高,且具有更好的稳定性。     

The E3 Ligase GmPUB21 Negatively Regulates Drought and Salinity Stress Response in Soybean

E3-ubiquitin ligases are known to confer abiotic stress responses in plants. In the present study, GmPUB21, a novel U-box E3-ubiquitin ligase-encoding gene, was isolated from soybean and functionally characterized. The expression of GmPUB21, which possesses E3-ubiquitin ligase activity, was found to be significantly up-regulated by drought, salinity, and ABA treatments. The fusion protein GmPUB21-GFP was localized in the cytoplasm, nucleus, and plasma membrane. Transgenic lines of the Nicotiana benthamiana over-expressing GmPUB21 showed more sensitive to osmotic, salinity stress and ABA in seed germination and inhibited mannitol/NaCl-mediated stomatal closure. Moreover, higher reactive oxygen species accumulation was observed in GmPUB21 overexpressing plants after drought and salinity treatment than in wild-type (WT) plants. Contrarily, silencing of GmPUB21 in soybean plants significantly enhanced the tolerance to drought and salinity stresses. Collectively, our results revealed that GmPUB21 negatively regulates the drought and salinity tolerance by increasing the stomatal density and aperture via the ABA signaling pathway. These findings improved our understanding of the role of GmPUB21 under drought and salinity stresses in soybean.     

基于时域有限元的近场单站导体柱微波成像

介绍了一种在自由空间中对导体柱近场单站电磁成像的时域数值方法.提出以不均匀分布的点--离散点描述法,来代替通常采用的有限项三角级数逼近的形状函数来描述散射体.在正过程中采用时域有限元法获得其近区散射场,逆过程则通过遗传算法来寻找最优解.以不均匀分布于导体表面点的矢径的模作为优化变量.以在整个迭代过程中,目标散射场和计算散射场的误差总和与目标散射场场值绝对值之和的比值作为目标函数,使目标函数达到最小值来获得导体柱在自由空间中的电磁成像.     

重力式挡墙下基础的设计方法探讨

对于重力式挡墙下筏式条基,采用不同的布置方式直接影响其造价.文章从理论上探讨了筏式条基的合理布置,并且通过工程实例验证了当筏式条基截面中心偏离挡墙合力点为e0与B/30中较小者时,筏式条基按受弯计算所需的配筋要比筏式条基截面中心与挡墙合力点重合时节省9～14%的配筋.当筏式条基底部土层沉降已基本完成且能提供100KPa左右以上地基承载力特征值时,建议设计时采用方案2所述的挡墙基础布置方式.