3Cr-3Mo二次硬化钢的回火组织和力学性能

研究了3cr—3Mo二次硬化钢淬火回火后的组织和力学性能。结果表明：随回火温度的升高，试验钢中先后析出M3c、M2c和M7C3等碳化物，在575℃回火时硬度达到峰值；400一575℃回火后试验钢的抗拉强度约为l600MPa，冲击韧性为30J／cm^2；回火温度高于600℃时，强度和硬度迅速下降，冲击韧性增加；640℃回火时，以M2C型碳化物为主，抗拉强度为1100MPa，冲击韧性增加至55J／cm^2。     

珠海市地下管线管理工作的具体措施

在建设部令第136号《城市地下管线工程档案管理办法》颁布前后,珠海馆从思想着手,从立法、宣传、教育、调研协调、具体措施等方面,将工作落到实处,为珠海市科学管理城市地下管线奠定了基础。     

海底管道系统失效故障树的建立及定性分析

受自然环境、管道腐蚀、第三方破坏及管理不善等因素的影响,海底管道系统在铺设及运行过程中常常会失效。文中以海底管道穿孔、凝管、断裂和设备故障等主要失效形式为顶事件建立了海底管道系统失效故障树,通过系统的定性分析得到了海底管道系统失效故障树的37个一阶最小割集,进而确定了影响海底管道系统失效的4项主要因素,并针对这些主要因素提出了相应的解决问题的措施。     

Controlled Synthesis of Ag2S,Ag2Se,and Ag Nanofibers by Using a General Sacrificial Template and Their Application in Electronic Device Fabrication

Nanofiber bundles of Ag₂S, Ag₂Se, and Ag have been successfully synthesized by making use of Ag₂C₂O₄ template nanofiber bundles, utilizing both anion‐exchange and redox reactions. The obtained bundles were polycrystalline nanofibers composed of nanoparticles in which the precursor morphology was well‐preserved, indicating that Ag₂C₂O₄ nanofiber bundles acted as a general sacrificial template for the synthesis of silver‐based semiconductor and metal nanofibers. Dispersing media and transforming reactants were found to be key factors influencing the chemical transformation in the system. In particular, separate single‐crystalline Ag nanofibers were obtained via a nontemplate route when ascorbic acid was used as a relatively weak reductant. An electrical transfer and switching device was built with the obtained Ag₂S and Ag nanofiber bundles, utilizing the unique ion‐conductor nature of Ag₂S and revealing their potential applications in electronics.     

负载型固体碱催化合成亚苄基丙酮

研究了用固体碱 KOH/Al_2O_3催化合成苯叉丙酮,确定了合成的最佳工艺条件:n(苯甲醛)∶n(丙酮)=1∶4.催化剂用量2g,催化剂最佳负载量12mmol/g,反应温度40～45℃,反应时间为3h,产率达88%以上。     

Aging response of the young’s modulus and mechanical properties of Ti-29Nb-13Ta-4.6Zr for biomedical applications

Alloys for implant devices require improved strength but a reduced Young’s modulus, in order to become mechanically more compatible with adjacent bone tissues. In this study, a new metastable β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (wt pct), was subjected to aging treatment to produce different microstructures, and the resulting mechanical properties, including the Young’s modulus, were measured. The Young’s modulus of this alloy is found to be sensitive to microstructures generated by various heat treatments. For microstructures varying from (α + β) to (α + β + ω) and (β + ω), the Young’s modulus increases with an accompanying increase in tensile strength and hardness, but decreases in ductility. The (β + ω) microstructure has a low strength, high modulus, and poor ductility and cannot be used for biomedical applications. For an (α + β) microstructure, the volume fraction of the phases is shown to be the main factor that determines the mechanical properties.     

苏北-南黄海盆地构造演化

苏北及南黄海盆地是由多期、多类盆地叠加的复合残留盆地,地质概况基本相似,成因演化近同,自元古界下扬子板块形成后,主要经历了古-中生代地台、中生代前陆盆地、走滑拉分盆地时期以及新生代断陷、坳陷盆地时期.在古生代-中生代发展过程中是一个整体,晚白垩世盆地演化出现分化,发育伸展盆地群,形成一系列叠置在中、古生代盆地之上的箕状断陷,箕状断陷的发育及分布明显受中-古生界内部先存逆冲断裂的控制.     

新的启迪

说点心里的话，建筑设计对青年人来讲是一条漫长的道路。建筑是一个载体，有精神一面，也有物质一面。有些建筑师拿着模型或未建成的设计来炒作，为了求名，生怕别人不知道。这对个人是小事，但若贻误了青年学子，那就是不可取的。     

Structured optimal and robust control with multiple criteria: a convex solution

In this paper, the design of controllers that incorporate structural and multiobjective performance requirements is considered. The control structures under study cover nested, chained, hierarchical, delayed interaction and communications, and symmetric systems. Such structures are strongly related to several modern-day and future applications including integrated flight propulsion systems, platoons of vehicles, micro-electro-mechanical systems, networked control, control of networks, production lines and chemical processes. It is shown that the system classes presented have the common feature that all stabilizing controllers can be characterized by convex constraints on the Youla-Kucera parameter. Using this feature, a solution to a general optimal performance problem that incorporates time domain and frequency domain constraints is obtained. A synthesis procedure is provided which at every step yields a feasible controller together with a measure of its performance with respect to the optimal. Convergence to the optimal performance is established. An example of a multinode network congestion control problem is provided that illustrates the effectiveness of the developed methodology.