诊断冷却系统的过热问题 你将获益多多

为客户检查和确定发动机过热的原因,往往会成为你手中一个＂烫手的山芋＂。不过,如果你知道该向客户询问哪些问题,并且已经向他们提问时,那么你也正逐步走向成功。     

复杂悬跨条件下的管线涡激振动分析(英文)

Spans occur when a pipeline is laid on a rough undulating seabed or when upheaval buckling occurs due to constrained thermal expansion. This not only results in static and dynamic loads on the flowline at span sections, but also generates vortex induced vibration (VIV), which can lead to fatigue issues. The phenomenon, if not predicted and controlled properly, will negatively affect pipeline integrity, leading to expensive remediation and intervention work. Span analysis can be complicated by: long span lengths, a large number of spans caused by a rough seabed, and multi-span interactions. In addition, the complexity can be more onerous and challenging when soil uncertainty, concrete degradation and unknown residual lay tension are considered in the analysis. This paper describes the latest developments and a .state-of-the-art. finite element analysis program that has been developed to simulate the span response of a flowline under complex boundary and loading conditions. Both VIV and direct wave loading are captured in the analysis and the results are sequentially used for the ultimate limit state (ULS) check and fatigue life calculation.     

混合动力汽车是通往零排放梦想的桥梁

全球各大汽车制造商如今都面临着巨大挑战，就是如何为传统燃油发动机寻找一种可持续发展的可替代能源。虽然几十年来，人们已经探索出了很多种可行的方法，但至今为止，还没有一种可投入大规模生产，并与传统内燃机相抗衡的解决途径。在全球温室效应加剧和油价飙高的压力下，汽车制造商责无旁贷，那么混合动力是否是一种有效的解决方案呢？     

What do commuters think travel time reliability is worth? Calculating economic value of reducing the frequency and extent of unexpected delays

The measurement of transportation system reliability has become one of the central topics of travel demand studies. A growing literature concerns the measurement of value of travel time reliability which provides a monetary cost of avoiding unpredictable travel time. The goal of this study is to measure commuters’ sensitivities to travel time reliability and their willingness to pay (WTP) to avoid unreliable routes. The preferences are elicited through a pivoted stated preference survey technique. To circumvent the issue of presenting numerical distributions and statistical terms to day-to-day commuters, we use the frequency of delay days as a means of measuring traveler’s sensitivities to travel time reliability. The advantage of using simplified measures to elicit traveler preferences for travel time reliability is that these methods simply compare days with high delay to days with usual travel time. It was found that travelers are not only averse to the amount of unexpected delay but also to the frequency of days with unexpected delays. The paper presents WTP findings for three measures: travel time, frequency embedded travel time, and travel time reliability. The ‘reliability’ increase in WTP for travel time is found to be nearly proportional to the frequency of experiencing unexpected delays. For example, the WTP for mean travel time is calculated at $6.98/h; however, reliability adds $3.27 (about 50 % of $6.98) to avoid unexpected delays ‘5 out of 10 days’. The results of the study would provide valuable inputs to cost-benefit analyses and traffic and revenue studies required for road tolling investment projects.     

Comparison analysis for subjective and objective weights of financial positions of container shipping companies

This paper explores the positions of financial ratios identified utilizing both subjective and objective weighting methods—the consistent fuzzy preference relation (CFPR) and entropy—based on questionnaires collected from experts and the financial statements of major shipping companies in Taiwan and Korea. The comparison of perceptions of financial ratios by country and by expert group illuminates some financial aspects that experts may have ignored or not paid close attention to during the business operating process, especially in today’s turbulent world shipping market. The major results of this paper show that experts in the two countries have different perceptions of the debt-to-equity ratio and that by combining the results of objective and subjective weights, categorization of financial ratios by quadrant can help decision-makers find business options and strategies to improve the financial performance of their companies. This research approach may be applied to other business entities, improving on the direct rating method used in previous studies.     

The future tourism mobility of the world population: Emission growth versus climate policy

Much of global passenger transport is linked to tourism. The sector is therefore of interest in studying global mobility trends and transport-related emissions. In 2005, tourism was responsible for around 5% of all CO₂ emissions, of which 75% were caused by passenger transport. Given the rapid growth in tourism, with 1.6 billion international tourist arrivals predicted by 2020 (up from 903 million in 2007), it is clear that the sector will contribute to rapidly growing emission levels, and increasingly interfere with global climate policy. This is especially true under climate stabilisation and “avoiding dangerous climate change” objectives, implying global emission reductions in the order of −50% to −80% by 2050, compared to 2000. Based on three backcasting scenarios, and using techniques integrating quantitative and qualitative elements, this paper discusses the options for emission reductions in the tourism sector and the consequences of mitigation for global tourism-related mobility by 2050. It ends with a discussion of the policy implications of the results.     

Research trends and agenda on the Belt and Road (B&R) initiative with a focus on maritime transport

The ‘Silk Road Economic Belt and the 21st-Century Maritime Silk Road’ (collectively known as Belt and Road, B&R) has been initiated by the Chinese government in 2013. The B&R is increasingly becoming a focal point for socio-economic–political interests because of its likely impact on land and sea transport and maritime logistics. The aims of this study were threefold: first, to provide an overview on the B&R, focusing on its key structural elements, such as transport corridors, city clusters, dry ports, infrastructure, zoning, and area development; second, to identify the expected impacts of the B&R on trade and implications on structural changes in transportation systems, port networks, and international logistics. Finally, to discuss major research trends and setting up of research agenda which will contribute to enriching the existing literature and shaping the global trade operations and drive economic growth in the context of the B&R.     

Cyclone Mitigation Perspectives in the Islands of Bangladesh: A Case of Sandwip and Hatia Islands

Most coastal areas of the world are now at risk from natural hazards such as cyclones, storm surges, beach erosions, tsunamis, sea level rises, and so on, resulting from geological and meteorological disturbances. In Bangladesh, during premonsoon and post-monsoon periods cyclone and tidal surges are considered the most catastrophic phenomena in coastal regions, including islands. Most coastal island residents of Bangladesh have been facing cyclones for centuries. The present study establishes a comparison between two neighboring islands, Sandwip and Hatia, of the Meghna estuary with respect to disaster reaction and management. Based on a questionnaire survey and observations, the study shows that the inhabitants of Hatia are more aware of and confident in disaster management than the inhabitants of Sandwip. Residents of both islands in the Meghna estuary have established trust in the warning signals following the heavy devastation of great cyclones of 1970, 1985, 1991, and 1997. The residents of Hatia have been facing cyclones and tidal surges more frequently than the residents of Sandwip due to the island's geographical location. In addition, shelter management and relief management are better developed in Hatia than Sandwip.     

Factors Influencing the Participation of Local Governmental Officials in the National Estuary Program

Participation by local governmental officials is not given the same attention in the literature as that of citizens, publics, technical experts, or stakeholders. Yet, local governments are often a keystone to successfully implementing and enforcing coastal management policies. Qualitative analysis of open-ended interviews with local government officials from three national estuary program applications in New England revealed factors related to nine themes that shaped decisions to participate or not. Three categories of factors help to clarify the different types of influence agencies have over local government officials' decisions about whether or not to participate: factors associated with the character of individuals, with the context, and with the process. This taxonomy helps to clarify the kinds of opportunities available to project leadership to influence local government officials toward participating in regional coastal management processes. An important finding is that project staff should listen and learn about the concerns of local government officials and then create a process that accommodates and overcomes barriers to their participation.     

Validating the results of a route choice simulator

This paper describes the validation of a route choice simulator known as VLADIMIR (Variable Legend Assessment Device for Interactive Measurement of Individual Route choice). VLADIMIR is an interactive computer-based tool designed to study drivers’ route choice behaviour. It has been extensively used to obtain data on route choice in the presence of information sources such as Variable Message Signs or In-Car Navigation devices. The simulator uses a sequence of digitized photographs to portray a real network with junctions, links, landmarks and road signs. Subject drivers are invited to make journeys between specified origins and destinations under a range of travel scenarios, during which the simulator automatically records their route choices. This paper describes validation experiments carried out during the period Summer 1994 to Autumn 1995 and reports on the results obtained. Each experiment involved a comparison of routes selected in real life with those driven under simulated conditions in VLADIMIR. The analysis included investigation of the subjects’ own assessment of the realism of the VLADIMIR routes they had chosen, a comparison of models based on the real life routes with models based on VLADIMIR routes, and a statistical comparison of the two sets of routes. After an extensive series of data collection exercises and analyses, we have concluded that a well designed simulator is able to replicate real life route choices with a very high degree of detail and accuracy. Not only was VLADIMIR able to precisely replicate the route choices of drivers who were familiar with the network but it also appears capable of representing the kind of errors made and route choice strategies adopted by less familiar drivers. Furthermore, evidence is presented to suggest that it can accurately replicate route choice responses to roadside VMS information.