Activity involvement and time spent on computers for leisure: an econometric analysis on the American Time Use Survey dataset

Internet is capturing more and more of our time each day, and the increasing levels of engagement are mainly due to the use of social media. Time spent on social media is observed in the American Time Use Survey and recorded as leisure time on Personal Computer (PC). In this paper, we extend the traditional analysis of leisure activity participation by including leisure activities that require the use of a PC. We study the substitution effects with both in-home and out-of-home leisure activities and the time budget allocated to each of them. The modeling framework that includes both discrete alternatives and continuous decision variables allow for full correlation across the utility of the alternatives that are all of leisure type and the regressions that model the time allocated to each activity. Results show that there is little substitution effect between leisure with PC and the relative time spent on it, with in-home and out-of-home leisure episodes. Households with more children and full-time workers are more likely to engage in in-home and PC related leisure activities (especially during weekends). Increments in the travel time of social trips result in significant reductions in leisure time during weekdays.     

Innovative systems for the transportation disadvantaged: Toward more efficient and operationally usable planning tools

When considering innovative forms of public transport for specific groups, such as demand responsive services, the challenge is to find a good balance between operational efficiency and 'user friendliness' of the scheduling algorithm even when specialized skills are not available. Regret insertion-based processes have shown their effectiveness in addressing this specific concern. We introduce a new class of hybrid regret measures to understand better why the behaviour of this kind of heuristic is superior to that of other insertion rules. Our analyses show the importance of keeping a good balance between short- and long-term strategies during the solution process. We also use this methodology to investigate the relationship between the number of vehicles needed and total distance covered - the key point of any cost analysis striving for greater efficiency. Against expectations, in most cases decreasing fleet size leads to savings in vehicle mileage, since the heuristic solution is still far from optimality.     

东风康明斯新领导团队走马上任——黄乃绪就任东风康明斯总经理,马天龙任常务副总经理

东风康明斯发动机有限公司日前宣布,原东风康明斯副总经理黄乃绪正式就任东风康明斯总经理。原康明斯涡轮增压技术系统中国区总经理兼无锡康明斯涡轮增压技术有限公司总经理马天龙（Mark O’Connor）出任东风康明斯常务副总经理。     

An improved procedure for allocating public transit operating subsidies in Canada

This article addresses the need for an improved methodology for the allocation of public transit operating subsidies (PTOS) by the provinces in Canada, to their respective municipalities. A PTOS allocation procedure which may be adapted by each province to meet its individual objectives is proposed. This allocation procedure consists of a two-part grant, the first is population-based in consideration of attributes of the urban area and the second is performance-based, in consideration of attributes of the transit system itself. Issues of implementation concern primarily extended data collection methods and the need for consistency in the use of transit system performance measures.     

康明斯2009年四季度强势反弹 2010年销售额预期达到110亿美元

2010年2月2日，康明斯公司公布了2009年四季度的业绩。全球主要市场优秀的销售表现．以及公司一系列控制成本措施得当，康明斯实现历史最好季度盈利收入。     

Additions to Mexican freshwater copepods with the description of the female Leptodiaptomus mexicanus (Marsh)

A survey on 10 temporary and permanent water-bodies, located at more than 2000 m above the sea level in the central part of Mexico resulted in the presence of 17 cyclopoid and five calanoid copepods. From the total taxa found, seven are new to the country: Leptodiaptomus assiniboiaensis (Anderson), Microcyclops dubitabilis Kiefer, Ectocyclops rubescens Brady, Eucyplops cf. bondi Kiefer, Eucyclops cf. prionophorus Kiefer, Eucyclops pseudoensifer Dussart, and Eucyclops cf. solitarius. The female of Leptodiaptomus mexicanus, a species known only from a single male found near Mexico City in 1929, is here described for the first time. Copepod fauna for each of the systems was highly diverse, with up to 12 species co-occurring in temporary ponds. This study revealed a mixture of north and south American taxa in the area.     

Experimental and numerical investigation on the derailment of a railway wheelset with solid axle

This paper presents the results of an experimental and numerical investigation on the derailment of a railway wheelset with solid axle. Tests were carried out under quasi-steady-state conditions, on a full-scale roller rig, and allowed to point out the effect of different parameters like the wheelset's angle of attack and the ratio between the vertical loads acting on the flanging and non-flanging wheels. On the basis of the test results, some existing derailment criteria are analysed in this paper and two new criteria are proposed. A model of wheel-rail contact is proposed for the mathematical modelling of the flange climb process, and numerical vs. experimental comparisons are used to obtain model validation.     

Substitution and complementarity patterns between traditional transport means and car sharing: a person and trip level analysis

Transportation - Car sharing is a new transport mode which combines characteristics of private and collective traditional transport means. Understanding the relationship of this mode with existing...