渝怀线隧道内接触网锚段关节安装调整技术

对渝怀线隧道内锚段关节的设计特点进行了分析,针对锚段关节转换悬挂、补偿装置设计形式提出为达到设计要求,接触网锚段关节施工应采用的安装调整技术。     

接触网锚段关节式电分相

我国的电气化铁道接触网通常采用的锚段关节式电分相有七跨式、八跨式和九跨式3 种,本文重点介绍了八跨锚段关节式电分相的结构、线索关系及中性无电区与机车取流的双弓间距关系。     

弹性链形悬挂锚段关节过渡跨吊弦长度的计算

引入当量线密度的概念,采用力学计算的方法,针对弹性链形悬挂五跨式锚段关节过渡跨整体吊弦进行分析,由于过渡跨具有2个悬挂点,一个是弹性链形悬挂,另一个是简单链形悬挂,且接触线呈屋面布置结构的特殊性。因此本文详细论述了锚段关节过渡跨整体吊弦计算模型的建立及计算公式的推导过程。     

Digging Deep: Managing Social and Policy Dimensions of Geoduck Aquaculture Conflict in Puget Sound,Washington

Shellfish aquaculture can result in conflicts among stakeholders who perceive impacts and tradeoffs regarding sense of place, aesthetic, recreational, economic, and ecological values. Pacific geoduck clams (Panopea generosa Gould 1850) are grown in intertidal plots using gear- and labor-intensive techniques that result in a high value export product. A confluence of issues has resulted in on-going social and legal tensions surrounding geoduck aquaculture in southern Puget Sound, Washington (WA), USA. Using interviews and document analysis, we explored stakeholder perspectives and policy issues related to geoduck aquaculture in southern Puget Sound. Twenty-three stakeholders were interviewed, including state agency employees, representatives of the aquaculture industry, nongovernmental organizations, landowners, a tribal member, and an academic. Nine state hearings board decisions on challenges to aquaculture permits were also analyzed. Stakeholders articulated a variety of perspectives regarding aesthetic, recreational, land-use, ecological, political, regulatory, and economic aspects of geoduck aquaculture activities. Hearings board cases addressed similar issues (aesthetic, ecological, and recreational), as well as challenges to restrictions on aquaculture. Potential strategies for managing this conflict include emphasizing best management practices, identifying and incorporating best available science, joint fact-finding approaches, and initiating and improving communication among all stakeholders.     

Ground-truthing social vulnerability indices of Alaska fishing communities

Abstract

Community vulnerability is increasingly evaluated through quantitative social indices, typically developed using secondary data sources rather than primary data collection. It is necessary to understand the validity of these indices if they will be used to inform policy and decision making. This paper presents a ground-truthing effort to validate quantitative indices that characterize the well-being of Alaska fishing communities. We utilized ethnographic data collected from 13 representative communities and a capital assets framework to ground-truth the indices, in which qualitative ranks of vulnerability were compared against quantitative indices. The majority (73.8%) of ranks were in complete or moderate agreement and the results indicate that most of the indices are representative of community vulnerability; yet some variables utilized to create the indices could be modified to better reflect realities in Alaska. Indices of commercial fishery engagement and reliance appeared to be more reliable than socio-economic indicators, particularly for smaller fishing communities. We also confirmed that the indices do not capture political, or ecological factors that affect levels of community vulnerability. We conclude that quantitative indices of community vulnerability are useful rapid assessment tools; however, they should be validated, and complemented with ethnographic data prior to their implementation as policy making and management tools.     

车路协同环境下重叠线路公交车速诱导策略

为了防止公交车辆在线路重叠运行区间产生公交串车,在站点附近形成交通瓶颈,提出一种采用车速诱导策略来调整公交运行状态的动态调度模型.采用车路协同环境下的公交运营调度方式,结合各线路独自运行时的乘客需求和车辆车头时距规律,在避免重叠区站点公交串车的前提下,实现了各线路车辆最大程度地维持各自独立运行时车头时距的优化目标.提出...     

高速铁路平竖重合段三维高阶连续曲线线形设计

针对平竖重合曲线段存在几何连续性衰减并引起列车运动状态突变的现象, 以三维曲线的Frenet标架为基础, 结合曲率、挠率建立三维车体运动状态模型, 得到了曲率、挠率与车体加速度、急动度的关系, 并通过该模型从三维角度分析了三维曲线的几何连续性等级对车体运动的影响; 考虑几何连续性对曲率、挠率的要求, 提出以曲线曲率、挠率变化最小为目标的线形选择方法, 利用三维欧拉曲线创建平竖重合段高阶连续曲线。研究结果表明: 传统平竖重合段曲线连接点处几何连续性存在衰减, 仅为1阶几何连续, 曲率、挠率对列车加速度和急动度起主导作用, 几何连续性的衰减是竖向急动度突增的主要原因; 二维设计曲线在起点处的竖向急动度为1.206~1.264 m·s^-3, 超过乘客舒适性运动学阈值0.240 m·s^-3, 难以实现二维线形的高阶几何连续; 提出的曲线设计方法对连接点处的曲率和挠率都有明确定义, 容易在连接点处实现高阶几何连续, 且不存在几何连续性衰减, 曲线的曲率、挠率变化最小, 可有效降低线形参数变化给车体运动带来的不良影响; 所建曲线的加速度与急动度在全程均连续且满足运动学阈值, 实现了2阶几何连续, 最大竖向急动度为0.149 m·s^-3, 为阈值的62.0%, 为二维设计的11.7%~12.3%, 有效地改善了行车稳定性与乘客舒适性; 所建曲线路径与二维设计相比变化小, 在2%~3%坡度差时, 水平、竖向坐标差分别为0.907~2.305、1.085~2.498m;所建曲线的设计参数同时也是车体运动状态的计算参数, 从而可根据列车运行条件直接优化线路的设计。     

解读宇文所安的“文化唐”概念

美国汉学家宇文所安教授在2010年出版的《剑桥中国文学史》中提出文化唐的概念。此概念与传统以朝代史划分文学史不同的是,以文学文化史作为贯穿文学史的核心。本文旨在阐明文化唐的概念,并探讨其对中国文学史学的启示。     

考虑区间重叠的多运营商公交调度优化

为解决多运营商在重叠区间的公交线路调度问题,在分析重叠区间特性的基础上,提出一种双层规划模型.上层模型代表政府机构,目标为使公交乘客总出行时间最小,变量为公交线路分配方案;下层模型代表运营商,目标为各运营商追求自身利润最大化,变量为运营线路的公交车发车间隔.应用NSGA-II算法(Elitist Non-Dominated Sorting Genetic Algorithm) 求解模型,并在长春市南关区北侧区域的公交线网进行案例分析.实验结果表明,优化后网络中公交乘客的总出行时间降低了5.93%,验证了模型的有效性.     

Federal consistency and state expectations

Abstract

The requirement in the Coastal Zone Management Act of 1972 that federal projects be consistent with approved state coastal zone management programs is an important incentive for states to complete their programs. As a condition of program approval, states must first consult with the federal agencies concerned and provide opportunities for comment, with the hope of avoiding conflicts. The consistency requirement is also subject to various exceptions whose scope remains to be determined. One such exception of uncertain extent is the exclusion from the coastal zone of federal lands “the use of which is subject solely to the sole discretion ... of the Federal Government....”; Despite these uncertainties, however, the consistency provision represents a major change in federal policy, which has traditionally allowed federal agencies to operate largely without concern for state land or water use requirements.