Seismic Rehabilitation of Deficient Exterior Concrete Frame Joints

The performance of rehabilitated reinforced concrete beam-column joints was compared with the response of existing joints designed to preseismic codes to assess proposed rehabilitation techniques. Six beam-column subassemblies with nonductile reinforcement detailing were tested. The joints were subjected to quasi-static load that simulates seismic forces. The first three specimens had inadequate anchorage length of the bottom beam bars. Two of them were strengthened by using carbon-fiber-reinforced polymer sheets attached to the bottom beam face and then tested. The other three specimens had no steel ties installed in the joint zone, in addition to inadequate anchorage length of the beam bars. Two of the beam-column joints were strengthened by glass-fiber-reinforced polymer jackets of the joint zone and steel rods or plates. The rehabilitation techniques were found effective in eliminating the brittle joint shear and steel bar bond-slip failure modes, and ductile beam hinging instead occurred.     

Role of Inventory Buffers in Construction Labor Performance

Buffers of material stockpile (inventory) are formed at the work level in construction to help manage production. The size of material stockpiles often has an important bearing on construction project performance. In construction projects, where conditions are often uncertain and variable, some have suggested that buffers be sized and located according to the conditions. New management thinking like lean construction and theory of constraints suggests that the size of buffers needs to be managed carefully, because when oversized, buffers are wasteful, impede workflow, and hinder performance. Research has shown that project variability can be affected with the careful deployment of buffers but has not really evaluated the impact on construction labor performance. This paper reports an exploratory analysis of the relationship between inventory (buffers) and construction labor performance with data collected from three commercial projects in Brazil. In this study, the size of the buffer between rebar fabrication and installation in the construction of a structural system is compared to the labor performance of the fabrication and installation crews. The results show that some buffer helps achieve the best labor performance in the construction operations studied.     

低能带隙聚合物的设计

低能带隙聚合物对光电器件具有重要的意义。综述了低能带隙聚合物的设计方法和思路．包括聚合物取代基修饰、降低链中交替单双键键长的差异、给体一受体的规整交替，以及梯形聚合物的合成。     

基于有限元和系统辨识的智能结构主动控制

探讨了一种压电智能结构的设计方法,包括动力学建模、控制器设计和闭环系统有限元仿真。首先采用有限元方法计算滤过白噪声激励下压电智能结构的响应,以此响应作为系统辨识方法的输入,采用基于观测器/K a lm an滤波器的系统辨识方法(O bserver/K a lm an filter iden tification,OK ID)得到系统的M arkov参数,亦即单位脉冲响应的采样值,然后采用特征系统实现算法(E igensystem R ea lization A lgorithm,ERA)得到系统的最小实现,基于此模型采用LQG优化算法设计鲁棒控制器,并将反馈控制引入有限元模型进行闭环系统仿真,根据仿真结果评价设计方案。此方法克服了有限元模型无法直接用于控制器设计的缺点,通过将反馈控制引入有限元模型,可用有限元方法研究控制器的性能,也适用于设计其它复杂智能结构。     

ZrO2/钙铝硅系微晶玻璃复合材料热处理制度研究

采用Sol-gel法制备ZrO2/CaO-Al2O3-SiO2系微晶玻璃复合材料,通过差热分析、X射线衍射和扫描电镜等对材料进行表征.结果表明:烧结温度范围为1035～1065℃,晶化温度约为870℃条件下所制得的复合微晶玻璃材料主晶相为t-ZrO2和β-CaSiO3,具有较高的抗折强度,可以用于制备高强度牙科材料.     

溶胶—凝胶法制备Ba_(1-x)Sr_xTiO_3超微粉的干凝胶热分解过程

采用溶胶凝胶法制备了纳米Ba1-xSrxTiO3铁电陶瓷粉体,并用红外—热重联用的方法,结合SEM和XRD实验结果,分析了前驱粉体的热分解产物及其中的化学过程。XRD和SEM测试结果表明,干凝胶在空气中800℃下保温2h得到纯钙钛矿结构的BST纳米晶粉体,晶粒尺寸大约为30nm。     

纳米技术在建筑材料中的发展与应用

综述了纳米科技的基本概念、产生、发展及其战略意义,讨论了国内外近几年纳米材料和纳米技术的研究成果及应用发展,并对纳米材料在高强度和高韧性纳米陶瓷材料、新型纳米结构的玻璃、塑料和橡胶制品、粘合剂、密封胶和润滑剂、特殊的光学性能材料、催化剂、水泥添加剂、新型防护材料、静电屏蔽材料、耐热、隔热、阻燃材料、涂料等建材领域的直接应用以及其潜在价值进行了讨论。     

绿色包装设计模式的解析

论述了绿色包装设计对于人与自然的生态平衡关系,以及如何提高其产品在国内外的市场竞争力.促使人们重新面对一个基本问题:市场需求什么样的产品包装,如何设计这些产品包装.基于可持续发展的战略思想,提出了探索新的包装设计模式,传达绿色资讯,引导绿色消费.     

钛在汽车工业中的应用及降低钛材成本的工艺

叙述了钛在减轻汽车自重、节约燃油、保护环境、降低噪声、提高汽车性能方面的优势和应用领域及趋势。介绍并评价了几种降低海绵钛与钛材成本的工艺技术。     

世界粉末冶金工业一瞥

简介了国外与国内的粉末冶金工业发展现状;详述了近年来出现的温压、流动温压、高速压制、动磁压制、AncorMax D压制的新技术以及选择表面致密化方法;并对烧结硬化材料、软磁复合材料、磁致热材料等粉末冶金新材料进行了评述.