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？     

汽车改装潮流中维修店的营利机会(下)

为提高汽车性能而进行的改装工作,可以为独立汽修店提供一些营利的机会,但许多汽修厂还没有意识到这一点。不过,与通常的维修业务不同的是,进行汽车改装所产生的后果,车主必须愿意承担至少一部分的责任。     

The sequenced activity mobility simulator (SAMS): an integrated approach to modeling transportation, land use and air quality

The persistence of environmental problems in urban areas and the prospect of increasing congestion have precipitated a variety of new policies in the USA, with concomitant analytical and modeling requirements for transportation planning. This paper introduces the Sequenced Activity-Mobility Simulator (SAMS), a dynamic and integrated microsimulation forecasting system for transportation, land use and air quality, designed to overcome the deficiencies of conventional four-step travel demand forecasting systems. The proposed SAMS framework represents a departure from many of the conventional paradigms in travel demand forecasting. In particular, it aims at replicating the adaptative dynamics underlying transportation phenomena; explicitly incorporates the time-of-day dimension; represents human behavior based on the satisficing, as opposed to optimizing, principle; and endogenously forecasts socio-demographic, land use, vehicle fleet mix, and other variables that have traditionally been projected externally to be input into the forecasting process.     

The Static Stability of Articulated Commercial Vehicles

This review of the state of the art emphasizes recent results that have been obtained in extending conventionalanalysis techniques to the treatment of “Highway Trains”, that is, to heavy trucks that have multiple articulation points and employ suspensions with multiple axles. Equations of motion applicable to the equilibrium turning performances of articulated vehicles are examined with respect to using analysis techniques involving steering gains, understeer gradients, effective wheel-bases, handling diagrams, and critical speeds. These examinations provide the basis for in sights into simplified approaches for understanding the steady turning mechanics of articulated, multi-axle vehicles riding on pneumatic tires.     

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.     

Welfare effects of congestion pricing in Singapore

This paper examines the Singapore Area License Scheme. Changes in scheduling and choices of transportation mode by commuters are discussed. Although the toll is shown to reduce travel times for many commuters, many commuters are shown to incur scheduling costs as a result of the toll. Using estimated parameters of an indirect utility function, welfare functions are computed to compare welfare levels prior to, and just after, the toll was put into place. The evidence suggests that the toll may have reduced welfare.     

2002款轻型卡车维修服务特别报道

21世纪的今天,轻型卡车和运动型轿车(SUV)已占据了美国汽车市场50％以上的份额。车主对这些车辆的实用性要求越来越高,汽车厂商也乐于为此加大技术投入,以满足车主越来越挑剔的需求。原因非常简单:轻型卡车和SUV能承载更多的货物,牵引船只或拖车,在泥泞、雪地和越野路面上平稳地奔驰,人们当然愿意掏腰包购买这些用途极为广泛的车型。但是,人们仍苛刻地追求豪华舒适的感受,还要求它们与同价位轿车具有相当的驾驶品质。     

2006年美国进口车新技术一览(上)

在美国,所有进口汽车制造商都推出了2006款新车型．其中包括两种混合动力车。这些进口车也将能达到美国国产车的维修技术要求,如按照SAEJ2534标准的车载电脑通用再编程技术。本田、日产、丰田以及马自达和宝马汽车都可通过网络实现这一功能。本文将介绍一些新的技术。     

2003年美国汽车技术展望

对美国生产的轿车而言,去年市场上似乎风平浪静。新推出的车只有几款,它们分别是:用以取代“土星S”的新型的“离子”轿车、“旁蒂克·Vibe”、采用增压发动机的“PT巡洋舰”和“霓虹”。还有一些改进型的车,如“林肯·LS”和“林肯·城市”。 虽然推出的新车不是很多,但对不起,我必须告诉你:CAN(控制器局域网)时代已经来临。这几年,市场已经有几款所谓的新一代故障扫描仪,这些扫描仪可以用来诊断CAN系统。除非你已