On the Range of the Common Cycle Time in a Road Network

In a coordinated road network, the optimal common cycle time is determined by evaluating the performance of the network in the given range of cycles. Normally, this range is determined by users’ experience. And a large range of common cycle time, e.g. \[0,0\] is chosen, which requires long computation time. This study considers that the optimal common cycle time ranges between the minimal and maximal value of intersections’ individual optimal cycle time. It is proved mathematically from the convexity condition, that the delay of the network and each individual intersection are convex functions of the cycle time according to Webster delay model. Finally, 2 000 random cases for the network composed of two intersections and of eight intersections are created to underline the proposed conclusions. The results of all cases confirm the validity, and show up to 90% improvement in computation time to compare with experience range. The signal optimization tool, Synchro, is also used to validate the conclusion by 50 random cases. The results confirm reliability further.     

Edward C. Webster (1909-1989).

Presents an obituary for Edward C. Webster, recipient of the 1982 Distinguished Award for Contributions to Canadian Psychology as a Profession and Professor Emeritus of McGill University. Webster died on February 15, 1989. His career was dedicated to the application of psychological principles to real life problems, not just in practice but in research, in administration, and in service to his profession and community. Although committed to the development of applied psychology generally, Ed's major impact on theory and research was in industrial psychology, particularly in personnel selection. Like many other practitioners, he made extensive use of the interview as an information gathering technique, upon which recommendations to hire were based. Another major contribution he made to Canadian professional psychology was undoubtedly the role he played in the Couchiching Conference on the training of applied psychologists, which culminated in the book he wrote in 1967, The Couchiching Report: Training in Professional Psychology in Canada. Ed Webster will be long remembered for his commitment to and promotion of applied psychology at McGill and in Canada, for his contributions to the literature in personnel selection, and for his support of the work of students and colleagues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

“多媒体物理教学课件库”网站的建设

通过分析物理教学 ＣＡＩ的发展动向,提出开发因特网上基于 ＷＥＢ的开放式多媒体计算机辅助物理教学课件库网站的建设构想。     

单交叉口多目标联合优化的信号配时研究

传统的交叉口信号配时大多只从提高车辆的通行效率这一角度出发,未考虑交叉口处的行人因素以及车辆尾气排放, 容易造成交通事故,加剧环境污染。 从车辆和行人的交通效益以及环保角度出发,在改进的 Webster 延误模型基础上提出了以 车辆延误、行人延误、停车率、通行能力、尾气排放为优化指标的多目标函数,利用改进的粒子群优化算法(PSO)对所建立的多 目标函数求出最佳信号周期;再利用流量比计算公式求出各个相位的红绿灯时间。 使用这种配时方案,在交通流量高峰期,可 以使车辆的延误降低 18. 7%,停车率降低 15. 9%,行人延误降低 17. 8%,尾气排放降低 38%;在交通流量低峰期时,可以使车辆 的延误降低 11. 6%,停车率降低 6. 9%,通行能力提高 8%,行人延误降低 28. 6%,尾气排放降低 5. 6%。 使用这种配时方案在一 定程度上可以提高道路通行能力、减少交通事故、减少尾气排放、降低道路拥堵。     

交叉口相位及信号配时优化

为缓解城市内的拥堵,本文选取北京市海淀区内一个典型单点交叉口,通过晚高峰期间交通调查所获得的数据,运用Webster信号配时法对交叉口重新进行信号配时设计,利用Synchro系统对不同配时设计方案进行仿真.研究结果表明:能够重新确定一种使交叉口延误最小、服务水平最高的配时方案,即在交叉口东西进口道各增加一个左转专用相位,并改变原有的信号周期配时时长.优化后的交叉口最大车流量和通过能力比由原来的1.26减少到1.01,平均控制延误由69.2 s减少到58.9 s,ICU服务水平由E级提升到了D级.     

Gregory Daniel Webster: Psi Chi/APA Edwin B. Newman Graduate Research Award.

Presents a citation for Gregory Daniel Webster, who received the Psi Chi/APA Edwin B. Newman Graduate Research Award "for an outstanding research paper whose findings report that APA journal articles became shorter in length after the year 2000." A brief profile and a selected bibliography accompany the citation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparation and characterization of copper-nickel bulk nanocrystals

Copper-nickel nanoparticle was directly prepared by flow-levitation method(FL) and sintered by vacuum sintering of powder(VSP) method. Several characterizations, such as transmission electron microscopy(TEM), scanning electron microscopy(SEM), X-ray diffraction(XRD), differential thermal analysis(DTA), and energy-dispersive X-ray spectroscopy(EDX) were used to investigate the prepared nanostructures. The results of the study show that FL method could prepare high purity Cu-Ni nanocrystals of uniform spheres with size distribution between 20 and 90 nm. After sintering the bulk nanocrystalline copper-nickel has obvious thermal stability and the surface Webster hardness increases with the rising sintering temperature. At the temperature of 900 ℃, the specimen shows higher surface Webster hardness, which is about two times of traditional materials. When the sintering temperature arrives at 1 000 ℃ the relative density of bulk nanocrystals can reach 97.86 percent. In this paper, the variation tendency of porosity, phase and particles size of bulk along with the changing of sintering temperature have been studied.     

信号交叉口Webster法延误计算修正模型

信号配时方案设计是否合理最重要依据是对信号交叉口进行延误分析与定量计算来判定,目前国际上最经典的模型是英国的Webster算法,但因其自身的局限性,并不能用来计算拥挤条件下的延误。通过对哈尔滨市部分十字型信号交叉口与T型信号交叉口,采用点样本法进行的延误调查数据,对各交叉口应用Webster算法进行延误理论计算值与实测值的比较。经分析,Webster算法与实测值有较大出入。在此基础上,使用SPSS软件建立与哈尔滨市交通情况相适应的信号交叉口Webster法延误计算修正模型。     

Thermal oxidation of InAs and characterization of the oxide film

The thermal oxidation of InAs and the properties of the resultant oxide films were studied. Uniform InAs oxide films with a resistivity of 10¹² Ω cm were obtained on InAs substrates by low temperature oxidation at around 400°C. The thermal oxide films are mainly composed of polycrystalline In₂O₃ and As₂O₃. Increasing oxidation temperature causes thermal decomposition of the As₂O₃ and the accumulation of elemental arsenic in the oxide film. The oxide resistivity decreases with increasing oxidation temperature, mainly as a result of the thermal decomposition of the As₂O₃. The interface state densities near the midgap of InAs are (2–5) × 10¹¹ cm^-2 eV^-1. A metamorphic layer is formed beneath the thermal oxide of InAs by high temperature oxidation above 500°C.     

铝合金回归热处理进展及其新应用领域

可热处理铝合金的回归热处理（ＲＨＴ）工艺既古老又新颖。回归现象是由于预脱溶ＧＰ区重新溶解。介绍了合金的力学性能与显微组织在ＲＨＴ过程中的变化。ＲＨＴ时间很短，温度应高于原先的时效温度。铝合金在ＲＨＴ后，加工成形性能恢复到时效前状态，可对材料进行局部或整体ＲＨＴ，对６×××系合金挤压型材施加ＲＨＴ及压装连接（ＣＦ）的开发成功大大扩大了挤压型材在交通运输工具（特别是汽车）及其他方面的应用。