A havelock source panel method for near-surface submarines

A panel method is described for calculating potential flow around near-surface submarines. The method uses Havelock sources which automatically satisfy the linearized free-surface boundary condition. Outputs from the method include pressure field, pressure drag, wave resistance, vertical force, trim moment and wave pattern. Comparisons are made with model tests for wave resistance of Series 58 and DARPA SUBOFF hulls, as well as with wave resistance, lift force and trim moment of three length-to-diameter variants of the DSTO Joubert submarine hull. It is found that the Havelock source panel method is capable of determining with reasonable accuracy wave resistance, vertical force and trim moment for submarine hulls. Further experimental data are required in order to assess the accuracy of the method for pressure field and wave pattern prediction. The method is implemented in the computer code “HullWave” and offers potential advantages over RANS-CFD codes in terms of speed, simplicity and robustness.     

美国铁路车钩缓冲装置的发展（续完）

3　关节式连接器和牵引杆3.1　关节式连接器 　　关节式连接器在客车上已有多年的使用历史，主要用于20世纪30年代一些轻型流线型客车上，但很少在货车上运用。1968年为切萨皮克*俄亥俄铁路制造的活顶漏斗车，其车体间的连接采用由美国铸钢公司研制的关节式连接器，不过并没有收到此类车的订单。20世纪70年代后期，开始使用长途拖车，这时使用单节具有足够长度的车体运载2个拖车已不再合理。虽然可以制造用于运载单节拖车的较短的普通车辆，但这种车辆不能有效利用2个四轮转向架的承载能力。1977年制造出了采用关节式连接器、6节编组的列车，每个车体都运载1个拖车。关节式连接器以切萨皮克*俄亥俄漏斗车连接器为设计原型，相邻车体共同支承在1台四轮转向架上，允许相互间在水平和垂直方向上有一定转角。位于端部2节车的外端以常规方式支撑在独立的转向架上。这样，6节车体（1个车组）仅由7台转向架支承，如按普通结构则需要12台转向架。这种车每辆有10个车体，取得了很大成功。     

From broken windows to a renovated research agenda: A review of the literature on vandalism and graffiti in the rail industry

The execution of vandalism and graffiti on rail property has a significant impact on rail authorities, the patronisation of rail services, expenditure, and the timely operation of services. There are also important social costs which stem from passengers feeling unsafe, not to mention the environmental costs of removing graffiti and repairing vandalism. In this review paper, we focus on the social, non-technical determinants of and deterrents to vandalism and graffiti in the rail industry. First, we consider the definitions of graffiti and vandalism that are often conflated. After providing some clarification on terminology, and proposing a media-centred approach to vandalism and graffiti, we consider various theorisations of the psychosocial determinants of vandalism and graffiti behaviour. We then turn to an empirical discussion of different technical and social, non-technical prevention programmes that have been trialled. With a focus on identifying what works and under what circumstances, we refer to international case studies of successful vandalism reduction initiatives from Europe, the United Kingdom, the United States of America and Australia. Based on a review of literature and practice, we outline a future research agenda to address vandalism and graffiti. We recommend lines of further research covering: theory, empirical data collection and practical initiatives. Specifically, we note the need for a trans-theoretical model of vandalism and graffiti, further ethnographic research and improved evaluation and benchmarking strategies. This is the first review dedicated to the topic of vandalism and graffiti in the rail industry and the first review of non-technical, social deterrents to vandalism and graffiti broadly.     

The Benefits for Rail Freight Customers of Vertical Separation and Open Access

Abstract

This paper reviews and analyses the benefits for rail freight customers of the two principal models for introducing competition in main line railway networks: (1) the vertical separation of infrastructure from operations; and (2) the introduction of competition providing other operators with open access to the network. The paper shows that traffic growth has generally been higher in those European countries that have liberalized most. It then examines in detail the impact of restructuring in Great Britain in terms of the competition, freight rates and traffic growth. The paper concludes that vertical separation benefits freight customers more than just open access.     

Rates and mechanisms of climate change: Implications for ports and harbours

The paper explores some of the key ocean-atmosphere processes relevant to the themes of ‘global warming“ and ‘sea level rise“ addressing some of issues that form the basis of the science. It is shown that both processes as well as the data used to characterise such processes demonstrate that a) there is no such thing as a single global sea level and b) changes in extreme storminess are not uniform worldwide. Instead, trends in storminess (including Asian typoon and Atlantic hurricane activity) exhibit marked regional variability with strong regional signature linked to episodes of major El Niño and La Niña activity. Similarly, satellite data demonstrates that whereas some ocean areas have recently experienced sea level rise caused principally by thermal expansion effects, other ocean areas have been subject to cooling and sea level lowering. This account provides an introductory account that discusses the rationale for understanding the regional variability in the nature of coastal flood risk to the world’s ports and harbours.     

Railway planning in developing countries: a case study of Colombia

This paper describes a study of possible network changes for the Colombian railway system. A cost model is developed and the variation of costs with traffic density and with gradient is analysed and found to be different from that expected from experience in developed countries. The evaluation of network changes is carried out by a form of systems analysis in which two new lines and many closures are examined. Closures are evaluated by means of social cost benefit analysis incorporating a consumers’ surplus approach. The study recommends fairly radical changes to the present network configuration, these involving the construction of one new line and the closure of several existing ones.     

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。     

Do transportation network companies increase or decrease transit ridership? Empirical evidence from San Francisco

Transportation - Transportation network companies (TNCs), such as Uber and Lyft, have been hypothesized to both complement and compete with public transit. Existing research on the topic is limited...     

Recreation Conflict Along New York's Great Lakes Coast

This study used goal interference theory to examine the recreation conflict among motorboat users, personal watercraft users, and riparian landowners. Data were collected from three types of owners in the New York Great Lake coastal area. Results indicated each of the four recreation conflict dimensions proposed in goal interference theory contained multiple factors. Logistic regression models indicated that one or more dimensions were significant in predicting perceived conflict and the models correctly predicted conflict in over 70% to 100% of the cases. Goal interference theory can be seen as a general model, but significance of the four dimensions depends on types of recreation activities and users.     

Climate change projections for variables affecting road networks in Europe

Global climate change will affect road networks during this century. The effects will be different in various parts of the world due to differences in local climate change and in the structure and properties of roads. In this paper, climate change projections are presented for climate variables that are most likely to affect the long-term performance of road networks in Europe. We apply four regional climate simulations up to the year 2100 using two plausible future emission scenarios. The results show that the changing climate will require significant adaptation measures in the near future in order to maintain the operability of the European road network.