An Internal State Variable Model for the Low Temperature Tempering of Low Alloy Steels

QuanitativelyaccuratePredictionsofquenchinduceddistOnionandresidualstressrelyontheabilitytopredictthemicrosthectUralevolUtionthroughOutthequenchProcess.InlowaIloysteels,cUrrenresearchMshavefOcusedontheformationldneticsoffetrite,pearlite,bainiteandmartensite.However,temPeringcanhavealargeinfluenceondistOnionandresidualstrCss,andeffortstoaccountforthislagbehindthemodelingofthePrimnyphasetransihons.AsafirststeptowardsaccountingfortemPerillg,wehavedevelOpedanintemalstatevariablemodelthatuses…     

South Carolina's diked tidal wetlands: The presisting dilemmas

Abstract

South Carolina has a significant stock of diked coastal wetlands, dating from the days of rice culture before the Civil War. A survey of those controlling these sites along the entire South Carolina coast reveals that many continue to be used for waterfowl hunting, with management practices becoming more intensive than they were when partial data were gathered a decade ago. It also suggests that most of the acreage involved is located in large fields, where management is more difficult and mosquito control problems are more likely. This survey also indicates that public access is limited, but that there is evidence of continuing conflict over ownership. This situation creates a persisting dilemma for coastal zone management, shaping conflicts between alternative strategies for the use of natural systems.     

A joint model for vehicle type and fuel type choice: evidence from a cross-nested logit study

In the face of growing concerns about greenhouse gas emissions, there is increasing interest in forecasting the likely demand for alternative fuel vehicles. This paper presents an analysis carried out on stated preference survey data on California consumer responses to a joint vehicle type choice and fuel type choice experiment. Our study recognises the fact that this choice process potentially involves high correlations that an analyst may not be able to adequately represent in the modelled utility components. We further hypothesise that a cross-nested logit structure can capture more of the correlation patterns than the standard nested logit model structure in such a multi-dimensional choice process. Our empirical analysis and a brief forecasting exercise produce evidence to support these assertions. The implications of these findings extend beyond the context of the demand for alternative fuel vehicles to the analysis of multi-dimensional choice processes in general. Finally, an extension verifies that further gains can be made by using mixed GEV structures, allowing for random heterogeneity in addition to the flexible correlation structures.     

Passenger conveyor economics

Operating and capital costs for a high speed conveyor are estimated from cost data for low speed conveyors and from estimates for high speed designs. Unit costs are developed with reference to theoretical and practical conveyor capacities, and to the effect of traffic peaking on average utilization. User benefits are modelled as the change in consumers surplus arising from the introduction of a conveyor on a linear street as an alternative to walking. Cost and benefits vary widely depending on system design and location and on characteristics of travellers. Benefit measurements should reflect the effects on travel demand of a proposed installation, changes in value of time with changes in mode, and the effects of benefit “dilution” associated with limitations on access to the conveyor.     

Rail network accessibility and the demand for inter-urban rail travel

This paper reviews methods that have and can be used to forecast the effect of changes in accessibility to the rail network on the demand for inter-urban rail travel and of available evidence on rail accessibility elasticities. It reveals that relatively little research has been conducted in this area and that the forecasting procedures that could be used imply large variation in accessibility elasticities, which has not been empirically justified. Fresh empirical evidence on two related matters is reported. First, the neglected area of choice set composition is examined and the extent to which rail is considered to be a realistic alternative for inter-urban journeys and the contribution that accessibility to the rail network makes to this are analysed. Second, rail trip rate models are presented that not only contain estimates of accessibility elasticities and of the effects of a range of socio-economic variables on the demand for rail travel, but also that allow tests of the accessibility elasticity variation implied by many forecasting procedures to be conducted. It is found that this elasticity variation is not empirically supported. It is concluded that there is only limited scope for increasing rail demand through improvements in rail network accessibility.     

Transformations and continuities of issues related to Chinese participation in the global seafarers’ labour market

Since the 1990s, Chinese seafarers have become a force to be reckoned with in the global seafarer labour market, particularly against the backdrop of the manning crisis. Compared with other groups of seafarers dominating the market such as the Filipinos and the Indians, they are commonly associated with perceptions of low cost, poor English skills, different safety/work culture, problems with the International Transport Workers’ Federation, etc. This article identifies transformations and continuities of problems related to Chinese seafarers in the global market in the last two decades or so by reviewing relevant Lloyd’s List reports as well as official documents and previous research. The review shows that Chinese authorities have been taking various initiatives to take advantage of the manning crisis and to expand and promote seafarer education, supply and export, which in general serve to make seafarers better educated and improve their communication skills. Although such initiatives have helped increase seafaring labour export, the success is nevertheless limited by tight government control on recruitment, which makes some foreign managers reluctant to employ Chinese seafarers.     

Can bus really be the new tram?

BRT appears to be less expensive to build and operate than tram systems but can it really approach the performance level of a tram system and what is the environmental performance of comparable systems?     

驾驶辅助系统(DAS):多种传感器数据的融合

最新的驾驶辅助系统(DAS)技术通过传感器数据融合,把来自不同信息源的传感器数据结合起来,形成更全面的有关道路状况的报告,从而让车辆和道路更安全。