一种基于并联机构的航天器姿态模拟装置的设计开发

航天器发射升空前进行地面测试和试验是航天器研制过程中的重要环节。文中针对一种基于并联机构的姿态模拟装置的设计开发,从位置分析、速度分析和虚拟样机的建造和仿真分析等方面对3UPS-PU并联机构进行研究,完成姿态模拟装置的设计,为航天器装配、试验和测试设备的设计提供一种新的思路。     

Influence of static pre-loading on the dynamic bending strength of concrete with particle element modeling

Experimental tests show that static pre-loading has a significant effect on the dynamic strength of concrete.Based on meso-scale particle element model,numerical simulations of dynamic bending tests with pre-loading are performed.Complete stress–strain relationships are then obtained.Significant increase in dynamic strength is found when the pre-loadings are imposed within the elastic limit of concrete.However,when the imposition of pre-loadings reaches the plastic or softening range,dynamic strengths may gradually decrease along with the increase in pre-loadings.The distribution of energy components and the failure modes are discussed to explain the mechanisms of the phenomena.     

本科生导师制激励问题研究

运用博弈论的分析方法解释本科生导师制在推行过程中遇到的激励问题。通过构建一个非对称信息的静态模型,发现导师指导学生的努力程度将取决于学校的惩罚力度、考核成本以及该制度给学校带来的收益,而学校对教师指导情况的考核概率则主要受到其制定的奖惩规则和教师科研水平的影响。     

A novel spherical-ordered macroporous CuO nanocatalyst for the electrochemical reduction of carbon dioxide

Journal of Applied Electrochemistry - The electrocatalytic reduction of CO2 is a promising research direction in resource utilization and sustainable energy development. However, there is still a...     

CA6140车床数控改造中机械装置设计技巧

介绍了普通车床数控改造中机械装置的几个独特设计，使得数控车床纵向进给系统结构更简单、性能更可靠、装拆更方便。     

激光快速成形Rene′88DT高温合金的时效强化研究

研究了时效时间对激光快速成形后时效硬化镍基高温合金Rene′88DT中沉淀相组织演化和力学性能的影响。发现随时效时间的增加，沉淀相y’略有长大，颗粒之间发生大颗粒吞噬小颗粒的粗化，时效40h后沉淀相颗粒粗化明显。对经不同时间时效后的激光快速成形Rene′88DT试样进行了硬度测试。结果显示，在时效时间为28h时，硬度有一峰值HRC49。在此基础上，采用1165℃，2h固溶、空冷＋760℃，28h时效的热处理工艺对激光快速成形标准拉伸棒样进行了热处理，拉伸结果显示成形件的抗拉强度较激光沉积态提高了400MPa，屈服强度接近同种材料的粉末锻造水平。     

Positive <Emphasis Type="Italic">L</Emphasis><Subscript>1</Subscript>-gain filter design for positive continuous-time Markovian jump systems with partly known transition rates

The paper is concerned with the problem of positive L ₁-gain filter design for positive continuous-time Markovian jump systems with partly known transition rates. Our aim is to design a positive full-order filter such that the corresponding filtering error system is positive and stochastically stable with L ₁-gain performance. By applying a linear co-positive Lyapunov function and free-connection weighting vectors, the desired positive L ₁-gain filter is provided. The obtained theoretical results are demonstrated by numerical examples.