Structural performance and design evaluation of HPS 70W bridge girders

An evaluation of the behavior of bridge girders containing HPS 70W high performance steel is conducted. The basis for this study is a three-span replacement bridge in Gaffney, South Carolina which utilizes HPS 70W girders within all negative moment regions. The study consists of in-situ measurements, which are currently in progress, experimental tests, and analytical investigations. Three half-scale specimens, each with different bracing and stiffener configurations, are tested in the structures laboratory at USC under monotonic and cyclic loading conditions. This paper presents results from analytical and experimental investigations and focuses on the strength performance of the girders. Studies on fatigue performance and in-situ measurements and long term monitoring are the subjects of subsequent papers. Data obtained from laboratory tests is used for the evaluation of the structural performance and the calibration and validation of computer models for design evaluations. Parametric studies through computer simulations are conducted to evaluate alternate designs. The findings of this study indicate that improved structural performance may be obtained when location of bracing is optimized and fabrication imperfection tolerances are minimized. Furthermore, the findings indicate that a similar level of structural performance at reduced cost is achieved when hybrid designs are specified in place of homogeneous HPS 70W cross sections.     

整车建模和转向性能分析

转向性能研究中一般会更多地关注方向盘力矩的变化。所以,转向系统对分析精度起决定性影响,必须建立详尽的模型来描述其内部特性,如惯性、刚度、摩擦、阻尼和助力曲线,这些因素对方向盘力矩变化有非常显著的影响,以致影响转向性能。本文阐述了在AMESim软件中建立液压助力转向系统和整车模型的过程。首先提出了一种新的计算转向阀过流面积的方法,以获得真实的转向助力特性,然后建立了包含这个比较详尽的转向系统的整车动力学模型,用于转向性能研究,最后选用了几种实车道路试验结果来验证此模型的准确性。     

400V/600W高压钠灯电子镇流器的设计与研究

属于第三代电光源的高压钠灯(HPS)及其电子镇流器是目前的研究热点之一。本文主要介绍了一种400V/600W的高压钠灯电子镇流器的设计及其特性的研究,并阐述了系统的设计思路,包括功率因数校正、半桥逆变、点火等,对于声谐振问题也作了一定的分析。最后给出了实验波形。     

高抗冲聚苯乙烯/微胶囊红磷/膨胀石墨阻燃材料的制备及性能研究

用熔融混合法制备了高抗冲聚苯乙烯(HIPS)/微胶囊红磷(MRP)/膨胀石墨(EG)无卤阻燃材料.用氧指数法、垂直燃烧及热重分析等方法研究了EG/MRP复配阻燃剂对高抗冲聚苯乙烯的阻燃作用,并对阻燃前后的HIPS复合阻燃材料进行了红外分析。结果表明,MRP和EG复配,可以使HIPS的氧指数提高到27%,垂直燃烧级别达到FV-0(1.5 mm);但是MRP与EG之间不存在协同阻燃效应;复配阻燃剂的作用机理为凝聚相阻燃机理,抗滴落剂的加入可以有效阻止材料燃烧时的滴落,提高材料的阻燃级别。     

铌对桥梁结构钢HPS 70W性能的影响

通过向桥梁结构钢HPS 70W中添加不同含量的铌元素,研究了合金元素铌对桥梁结构钢的力学性能、显微组织和析出相粒子的影响。结果表明,铌对桥梁结构钢HPS 70W低温韧性、强度和塑性有显著的作用。     

建构主义理论在科普展示中的应用与思考

建构主义学习理论强调教学以学习者为中心,学习者是认知主体,教师是意义建构的帮助者、促进者。本文通过对建构主义学习理论内涵与本质的探究,结合科技馆常设展的三类展示方式,尝试性地探讨了基于建构主义学习理论下"魔方机器人"展项研发的应用实践。     

高压钠灯电子镇流器建模与仿真

高压钠灯（HPS）电子镇流器是1个非线性系统,多采用电路模型对其进行设计与分析。为了实现对高压钠灯电子镇流器的闭环控制,需建立其动态数学模型。文中在建立电子镇流器各单元数学模型基础上,综合出整机数学模型。Matlab＼Simulink仿真与实际测量对比表明,本文建立的数学模型准确描述了高压钠灯电子镇流器运行状态,为闭环控制算法建立提供了依据。     

Tackling global electricity shortage through human power: Technical opportunities from direct or indirect utilizations of the pervasive and green human energy

With the energy and environmental problems becoming increasingly serious, human power, as a pervasive, renewable, mobile and environment friendly energy, draws more and more attention over the world. In this paper, the most basic features of human power are presented. The currently available human power harvesting theories and devices are briefly reviewed and compared. Further, direct or indirect utilization of human power in daily life, especially transportation and home appliances, such as human-powered car, watercraft, aircraft, washing machine and television etc. are summarized. Considering that the total energy from an individual is rather limited, as previously focused by most of the former works, it is conceived in this paper that an important future for large scale use of human powers lies in the efficient conversion, collection and storage of such energy from discrete people and then use it later on as desired. With the huge amount of energy gathered, the application category of human power would be significantly expended. Starting from this point, three technical ways towards efficiently utilizing human power are sketched, which are termed as human-powered grid (HPG), human-powered charger (HPC) and human-powered storage (HPS), among which, HPG is capable of collecting the electric power produced by each individual at different regions and thus can supply unique and flexible power to the customers covered in the area, without relying on the conventional electricity grid. The HPC can then charge various kinds of electrical devices instantly by a human driven generator which converts human power into electricity. Finally, the HPS can store electricity in time for later use. In this way, even for the devices requiring electricity that is strong enough, the collected human power can also serve as its reliable energy source. Meanwhile, utilization of human power becomes rather convenient and timely which guarantees its practical value. It is expected that with further research and increasing applications, human power could partially relieve the current global electricity shortage and environmental issues via its pervasive contribution.     

高性能桥梁用钢HPS70W的研制开发

介绍了通过向钢中添加Cr、Mo等合金和采用TMCP工艺,开发生产符合或超过美国标准《桥梁结构钢ASTMA709》的高性能桥梁用钢HPS70W,该钢具有良好的热影响区硬度和焊缝低冷裂纹敏感性以及良好的焊接性能和低温韧性,是现代化桥梁用钢的优秀材料。     

软起动器在膨胀机上的应用

介绍了软起动器在膨胀机上的应用,并介绍了软起动器的工作原理及应用效果.