The Quiet Revolution in Visual Resource Management: A view from the coast

Abstract

This introductory piece traces the growth of knowledge and activity associated with visual resource management in general. A specific framework of questions regarding methods of coastal zone visual resource management is presented. The state‐of‐the‐art in methodological studies is listed for each question, and the methodological questions are related to the major articles with the special issue of the Coastal Zone Management Journal. Major legal federal statutes, state statutes, and court cases are reviewed in light of visual resource management in the coastal zone. The remaining articles within the special issue that deal with integration of VRM into decision‐making are then arrayed against a management framework. This framework includes regulatory situations for (1) public land management and planning, (2) public projects involving private lands, and (3) public regulation of private projects.     

Improving Tidal Turbine Performance Through Multi-Rotor Fence Configurations

Constructive interference between tidal stream turbines in multi-rotor fence configurations arrayed normally to the flow has been shown analytically, computationally, and experimentally to enhance turbine performance. The increased resistance to bypass flow due to the presence of neighbouring turbines allows a static pressure difference to develop in the channel and entrains a greater flow rate through the rotor swept area. Exploiting the potential improvement in turbine performance requires that turbines either be operated at higher tip speed ratios or that turbines are redesigned in order to increase thrust. Recent studies have demonstrated that multi-scale flow dynamics, in which a distinction is made between device-scale and fence-scale flow events, have an important role in the physics of flow past tidal turbine fences partially spanning larger channels. Although the reduction in flow rate through the fence as the turbine thrust level increases has been previously demonstrated, the within-fence variation in turbine performance, and the consequences for overall farm performance, is less well understood. The impact of turbine design and operating conditions, on the performance of a multi-rotor tidal fence is investigated using Reynolds-Averaged Navier-Stokes embedded blade element actuator disk simulations. Fences consisting of four, six, and eight turbines are simulated, and it is demonstrated that the combination of device- and fence-scale flow effects gives rise to cross-fence thrust and power variation. These cross-fence variations are also a function of turbine thrust, and hence design conditions, although it is shown simple turbine control strategies can be adopted in order to reduce the cross-fence variations and improve overall fence performance. As the number of turbines in the fence, and hence fence length, increases, it is shown that the turbines may be designed or operated to achieve higher thrust levels than if the turbines were not deployed in a fence configuration.

     

Recent progress in the genetics of generalized vitiligo

Vitiligo is an acquired disease characterized principally by patchy depigmentation of skin and overlying hair. Generalized vitiligo (GV), the predominant form of the disorder, results from autoimmune l...     

Conceptualizing Social Outcomes of Large Marine Protected Areas

There has been an assumption that because many large marine protected areas (LMPAs) are designated in areas with relatively few direct uses, they therefore have few stakeholders and negligible social outcomes. This article challenges this assumption with diverse examples of social outcomes that are distinctive in LMPAs. We define social outcomes as inclusive of both social change processes and social impacts, where “social” includes all perceptual or material human dimensions. We draw on five in-depth case studies to report social outcomes resulting from proposed or designated LMPAs in Bermuda, Rapa Nui (Easter Island), Kiribati, Palau, and the Commonwealth of the Northern Mariana Islands & Guam. We conclude: (1) social outcomes arise even in remote LMPAs; (2) LMPA efforts generate social outcomes at all stages of development; (3) LMPAs have the potential to produce outcomes at a higher level of social organization, which can change the scope and type of affected populations and, in some cases, the nature and stakes of the outcomes themselves; (4) the potential for LMPAs to impart distinctive social outcomes results from their unique geographies and/or intersection with high-level politics and policy processes; and (5) social outcomes of LMPAs may emerge in the form of social change processes and/or social impacts.     

美国铁路车钩缓冲装置的发展(待续)

介绍美国铁路车钩缓冲装置的发展过程、结构特点及运用情况。     

铁道车辆液压减振器的工作原理和数值模型

基于液压减振器的工作原理、内部结构和阀元件的性能,建立了一个新的液压减振器数值模型。该数值模型不仅将阻尼力作为减振器活塞杆的速度与位移的函数,同时还含有用于描述内部结构的基本参量,可以清楚地描述液压减振器的阻尼机制。应用该模型可进行液压减振器的动态性能分析、结构设计、元件选用等。模型计算结果与实验数据有较好的符合性。该数值模型易于实现计算机数值仿真,可以应用于车辆系统动力学性能的研究和减振器的结构参数、动态性能对车辆舒适性和稳定性影响的深入分析。     

地铁工程施工事故与风险管理

参考国际隧道协会所建议的分级系统,将2001-2006年间在亚太地区地铁工程施工期间所发生的43个事故,依其后果的严重性分级,以作为发展地下工程风险管理的基础.纳入考量的项目包括人员伤亡、经济损失及对民众生活的影响、工期的延误,以及对交通的影响.并以新加坡政府在尼诰大道灾变后所采取的一连串措施为例,列出地下工程风险管理的要素,勾画出地铁风险管理制度的基本架构.     

Route swapping in dynamic traffic networks

A dynamic traffic assignment (DTA) model typically consists of a traffic performance model and a route choice model. The traffic performance model describes how traffic propagates (over time) along routes connecting origin-destination (OD) pairs, examples being the cell transmission model, the vertical queueing model and the travel time model. This is implemented in a dynamic network loading (DNL) algorithm, which uses the given route inflows to compute the link inflows (and hence link costs), which are then used to compute the route travel times (and hence route costs). A route swap process specifies the route inflows for tomorrow (at the next iteration) based on the route inflows today (at the current iteration). A dynamic user equilibrium (DUE), where each traveller on the network cannot reduce his or her cost of travel by switching to another route, can be sought by iterating between the DNL algorithm and the route swap process. The route swap process itself takes up very little computational time (although route set generation can be very computationally intensive for large networks). However, the choice of route swap process dramatically affects convergence and the speed of convergence. The paper details several route swap processes and considers whether they lead to a convergent system, assuming that the route cost vector is a monotone function of the route inflow vector.     

Travel time reliability: a review of late time valuations,elasticities and demand impacts in the passenger rail market in Great Britain

This paper provides an extensive review and reconciliation of British and European evidence relating to the value of, and demand responses to, rail reliability. In particular, we compare the elasticities implied by stated preference valuations of late time with directly estimated lateness elasticities. We find that the implied lateness elasticities are substantially greater than those directly estimated. A possible explanation for this is that lateness has been over-valued, but more sobering explanations would be to suggest that, whilst rail travellers dislike unreliability, they may be unwilling or unable to reduce their rail travel in response to experiences of poor performance, or else conventional economic approaches to deducing elasticities are not appropriate. The findings have been used to update the recommendations of the UK rail industry’s Passenger Demand Forecasting Handbook.     

微观仿真在城市停车设施规划中的应用

为研究停车场规划和可达性对城市路网的影响,在世界范围内的三个不同城市应用微观仿真模型模拟停车设施规划。描述了三个城市采用的不同研究方法及得到的研究结果。三项研究都试图找到由驾驶人寻找停车位而造成的城市交通拥堵的解决方法。同时,在测试设计方案时,都使用了S-Paramics微观仿真模型。