Proxy-Based Hierarchical Distributed Mobility Management for Tactical Networks

An important requirement in a military domain is a highly reliable mobility management method, especially when components of the networks are moving in tactical network environments. To increase reliability, the mobility management technology of the tactical network should be able to reflect the characteristics of the tactical network, such as a limited environment, failure, and hierarchical unit structure. In this paper, we propose a proxy-based hierarchical distributed mobility management scheme, which is highly focused on tactical networks. Considering the characteristics of tactical networks, the proposed scheme is composed of the following: 1) a proxy-based method, 2) a distributed mobility management method that synchronizes a mobility database between entities, and 3) a method of managing mobility by dividing the tactical network into upper and lower layers. Mathematical analysis and modeling and simulation results demonstrate that the method outperforms the existing state-of-the-art method in overcoming entity failure, handover cost, and delay in tactical environments.     

Impact of injection limitations on the contact resistance and the carrier mobility of organic field effect transistors

The contact resistance as well as the mobility have developed to key performance indicators for benchmarking organic field-effect transistors. Typically, conventional methods for silicon transistors are employed for their extraction thereby ignoring the peculiarities of organic transistors. This work outlines the required conditions for using conventional extraction techniques for the contact resistance and the mobility based on TCAD simulations and experimental data. Our experimental data contain both staggered and coplanar structures fabricated by exploiting different optimization techniques like SAM treated electrodes, different shearing speeds, PS blending and silicon oxide functionalization. In addition, the work clarifies how injection limited current–voltage characteristics can affect high-performance organic field-effect transistors. Finally, we introduce a semi-physical model for the contact resistance to accurately interpret extracted benchmark parameters by means of the transfer length method (TLM). Guidelines to use conventional extraction techniques with special emphasis on TLM are also provided.     

缝合城市机动性与可持续发展的裂痕——中欧大学联合城市规划设计竞赛之回顾

现代城市的发展很大程度上依赖高效运转的城市交通系统。城市交通的改善的确给我们带来了便利，促进了地区的发展，但大型城市变通设施割裂了城市的肌理，湮灭了城市的特性，我们的城市正在变成一堆堆构筑物的集合体，滚滚车流在带来商机的同时也带来了日益严重的环境问题，导致城市品质的退化。如何保持机动性与可持续发展之间的协调是我国城市普遍面临的巨大挑战，这既需要先进的理念，更需要不同专业知识、不同文化背景的专业人员的其同探讨。以“城市机动性和可持续发展”为主题由中欧四国六所大学联合举行的的城市规划设计竞赛，标志着一种全新的探讨。我们相信法国动态城市基金会的一系列学术活动必将会影响到城市交通规划的价值取向。     

空间的叙事--对张应鹏无锡南洋学院的一种阅读

空间不是一种苍白的存在,它直指建筑的生命意识;空间不是设计者的附庸,它以独立的思想与情感讲诉自己的故事。这种叙事是开放的,任何空间的参与者可以融入自己的话语,进行自己的解码与编排;这种叙事是流动的,无休无止,没有确切的来龙去脉;这种叙事是透明的,活动于空间内的人和物永远是真实的展露;这种叙事是感性的,只有善感的心灵才能感知它的存在。     

Job Search Networks and Strategies in Scattered-site Public Housing

How does poverty dispersal influence the job search tactics and networks of poor women? Using the results of interviews with 253 women living in dispersed and small clusters of public housing, this paper examines how job networks and search tactics may vary. The premise is that the mechanisms involved in connecting poor residents of more affluent areas with opportunity may consist of both social connections and new strategies for accessing opportunity. The paper finds that dispersed residents have job networks containing more diverse information. Second, dispersed residents more often used formal methods to find their most recent job. Third, dispersed residents seek better jobs, net of demographic controls, search method, and search outcome. The paper discusses the implications of these findings for the design of housing mobility and mixed-income housing programmes, the current policy emphasis at the US Department of Housing and Urban Development.     

Short-term effects of countermeasures for improved safety and mobility at marked pedestrian crosswalks in Borås, Sweden

The Swedish code concerning car drivers' responsibility to give way to pedestrians was strengthened in 2000. The primary aim of this study is to evaluate the short-term effects of the change in code. Another goal is to look at the effects of the reconstruction of four sites in Bor?s, Sweden. One site had changes made prior to the change of code, two test sites had countermeasures implemented during the study, and one comparison site was left unchanged. All the sites were chosen because schools were situated nearby. The focus of the evaluation was on children and elderly as pedestrians and cyclists. The goal of traffic calming of a 90 percentile driving speed below 30 km/h was not fulfilled at any of the test sites. A conclusion is that the height of a speed cushion is important. After the speed cushions were lowered from 70 mm to 55 mm, the 90 percentile speed increased from 34 km/h to 41 km/h. Sites with no speed cushions had much higher speeds. The design of an intersection influences road users' behavior. At the site where one crosswalk was removed, pedestrians that were using the remaining marked crosswalk were given way to less frequently than at the other sites. At intersections where most pedestrians used marked crosswalks, the children benefited the most in mobility. At the intersection where pedestrians used marked crosswalks to a lower extent after reconstruction, children and the elderly had the smallest increase in frequency of being given way to. After reconstruction to a court-yard street, the pedestrians were given way to a lower extent compared with the other sites, though the vehicle speeds were the lowest observed at this study. At the sites were no physical changes were made, the change of code improved driver yield behavior, but no more towards children than other age groups.     

变自由度4-~xP~xR~xR~xR~yR_N并联机构

提出一种变自由度4-xPxRxRxRyRN并联机构,该机构中与动平台4边相连的4个转动副两两相对且轴线重合(记为u轴和v轴).运用螺旋理论对机构的自由度进行分析和驱动副选取.初始位形下,4-xPxRxRxRyRN并联机构的动平台平行于定平台,此时动平台具有3个连续的移动自由度和两个瞬时转动自由度,其转轴可为平行于定平台的任何两条直线.动平台仅可绕u轴或v轴从初始位形下发生连续转动,此时动平台具有3个连续的移动自由度和1个连续转动自由度,转轴为u轴或v轴,且这两个转动自由度互斥,即如动平台先绕u轴发生连续转动后,就不能绕v轴发生连续转动,必须待动平台再次平行于定平台时才能切换,反之亦然.为实现自由度切换的完全可控,4-xPxRxRxRyRN并联机构需采用5个驱动器进行冗余驱动.     

基于IP的WLAN快速移动性分析

本文介绍了移动节点在无线局域网（WEAN）中移动的不同类型,分析如何克服移动节点在不同Ess之间移动切换时引起的较大的时延,提出快速切换的方法。在引入分层移动IP方案的基础上分析提前切换方法。分析表明,分层方案和提前切换方法结合使用,能很好的降低切换时延,把切换对通话的影响降低到最小。     

Safe pedestrian crossings for children and elderly

In May 2000, the Swedish code governing the conduct of drivers at marked crosswalks became stricter with the intent to improve safety and mobility for pedestrians. A crash analysis based on a macro study of all of Sweden suggests that the injury risk in marked, not reconstructed, crosswalks increased by 27% for pedestrians and 19% for bicyclists. The reason for this may be that pedestrians get a false sense of safety with the new code. Reconstructions aiming at lowering speeds are indeed needed for the change of code to be positive. The 90-percentile speed should not exceed 30 km/h or safety will deteriorate. However, low speed by itself may not guarantee optimal safety. Safety can be further improved at sites, which already have been reconstructed to ensure low speeds. Results based on field data collected at sites close to schools in Malm?, Trollh?ttan and Bor?s in Sweden, and in-depth studies and other analyses of Finnish and Swedish police-reported crashes, suggest that safety of children and elderly is further improved at sites where visibility, orientation and clarity are sufficient. Also, marking crosswalks may increase yield rates (expected improvement 6%) towards pedestrians; and speed cushions situated at a longer distance from the marked crosswalk increase yield rates towards pedestrians and cyclists compared to speed cushions closer by.