Methods of analysis for vehicle soak time data

Vehicle soak time, the duration of time a vehicle’s engine is at rest prior to being started, and its distribution function are important transportation activity data inputs for mobile emissions inventory estimation due to their impacts on vehicle start and evaporative emissions. This paper provides vehicle emission researchers with an overview of statistical analysis methods relevant to analyzing vehicle soak time data. Many of these methods are already in use in emissions research and have appeared in the literature. These methods are reviewed and further details regarding the implementation and interpretation of these methods are provided. Statistical methods relevant to the analysis of soak time data that have yet to appear in the emissions literature, including kernel density estimation and generalized linear models, are also introduced. Advantages and disadvantages of the methods are compared and theoretical justification is provided. Issues of correlated observations and censored data are discussed. General guidelines for the analysis of soak time data, such as stratification by start type and geographical region, are established. Finally, a subset of the statistical methods discussed is used to analyze the US Environmental Protection Agency’s 3-city data.     

The influence of oceanographic scenarios on the population dynamics of demersal resources in the western Mediterranean: Hypothesis for hake and red shrimp off Balearic Islands

The aim of the present paper is to study the relationships between some climatic indices and parental stock, recruitment and accessibility to trawl fishery of hake (Merluccius merluccius) and red shrimp (Aristeus antennatus) off Balearic Islands (western Mediterranean). Available annual catch per unit effort, recruitment and spawning stock biomass have been used as biological data. As environmental data, the meso-scale IDEA index and the large-scale North Atlantic Oscillation (NAO) and Mediterranean Oscillation (MO) indices have been used. To analyze possible links between these indices with the population dynamics of demersal resources, two non-linear approaches have been applied: (i) stock–recruitment relationships from Ricker and Beverton–Holt models, by sequentially incorporating environment factors; (ii) generalized additive modelling, both classical general and threshold non-additive models were considered. The latter simulate an abrupt change in explicative variables across different phases (time periods or climatic index values). The results have shown that two oceanographic scenarios around the Balearic Islands, associated with macro and meso-scale climate regimes, can influence the population dynamics of hake and red shrimp. This is especially true for recruitment, which seems to be enhanced during low NAO and IDEA indices periods. During these periods, colder-than-normal winters generate high amounts of cold Western Mediterranean Intermediate Waters (WIW) in the Gulf of Lions, which flow southwards and reach the Balearic Islands channels in spring, increasing the productivity in the area. This oceanographic scenario could also be favourable to the distribution of hake on the fishing grounds where the trawl fleet targets this species, increasing its accessibility to the fishery. Both spawning stock and abundance of red shrimp seems to be also enhanced by high MO index periods, which could reflect the increased presence of the saline and warm Levantine Intermediate Waters (LIW) in the study area, extending over the fishing grounds of this species. The proposed interactions can be useful to assess and manage these important demersal resources.     

Potential benefits of an adaptive forward collision warning system

Forward collision warning (FCW) systems can reduce rear-end vehicle collisions. However, if the presentation of warnings is perceived as mistimed, trust in the system is diminished and drivers become less likely to respond appropriately. In this driving simulator investigation, 45 drivers experienced two FCW systems: a non-adaptive and an adaptive FCW that adjusted the timing of its alarms according to each individual driver’s reaction time. Whilst all drivers benefited in terms of improved safety from both FCW systems, non-aggressive drivers (low sensation seeking, long followers) did not display a preference to the adaptive FCW over its non-adaptive equivalent. Furthermore, there was little evidence to suggest that the non-aggressive drivers’ performance differed with either system. Benefits of the adaptive system were demonstrated for aggressive drivers (high sensation seeking, short followers). Even though both systems reduced their likelihood of a crash to a similar extent, the aggressive drivers rated each FCW more poorly than their non-aggressive contemporaries. However, this group, with their greater risk of involvement in rear-end collisions, reported a preference for the adaptive system as they found it less irritating and stress-inducing. Achieving greater acceptance and hence likely use of a real system is fundamental to good quality FCW design.     

轨道运输噪音改善研析与对策——以台北捷运地下隧道为例

台湾因人口集中都会区且道路年增率远不及车辆年增率,形成都会区内及城际道路交通日益频繁与拥塞,台湾目前陆运交通主流与世界趋势相同,主要以轨道运输系统为陆运交通主要解决方案,同时近年来在降低环境污染及增加能源使用效能之呼声下,更使得铁路运输亦再度成为最佳解决方案.近年来台北捷运系统中和线古亭站穿越民房下方潜盾隧道段、维修线中华路区段及板桥线西门站至龙山寺站地下隧道,沿线接获越来越多居住其上的居民对振动噪音污染生活质量之抱怨与不满,同时因民众环保意识的日渐抬头,民众对捷运行驶的噪音愈来愈不能忍受,噪音陈情的地点也愈来愈多,目前虽采取许多改善措施,但似乎不能满足沿线居民的需求.此篇论文即针对轨道运输系统中台北捷运地下隧道分轨道噪音之成因进行分析,并经分析评估,拟定出各轨道噪音案在地下隧道的防治对策,并对部分防治对策做-长期监测,并对部分监测数据进行初步分析比对,厘清对策与成因在理论上及实务上之成效比对,从而进行设计上之回馈,以提供轨道运输在环境噪音防治之最佳方案.     

轨道运输隧道安全疏散系统——以台北捷运为例

台湾近年来新兴轨道运输系统方兴未艾,都市轨道运输系统,因其路线多经过都市闹区,故常采用地下型式兴建,当发生意外事故或灾变时,乘客能否安全逃生必须倚赖系统对隧道内与地下车站之乘客安全疏散所设计的逃生设备及事前完备规划的操作程序;目前台北捷运系统在隧道段及地下车站之灾害处理对策部份,已属成熟,由于台北捷运系统为台湾都会区轨道运输系统最先施作者,其规划设计除参考国外捷运系统之相关规划设计准则外,并融合台北都会区域活动特性而订定了台北捷运系统地下隧道乘客逃生操作程序,本文将台北捷运系统规划隧道安全疏散程序及地下车站乘客疏散原则,作一全面性说明及分析,希望能提供国内其它轨道运输隧道系统安全规划之案例参考.     

A Novel Approach to Vehicle Dynamics using the Theory of a Cosserat Point and its Application to Collision Analyses of Platooning Vehicles

A fully three-dimensional, computationally inexpensive vehicular model is presented. In contrast to traditional rigid body models, the vehicle's sprung mass is modeled as a (nonlinearly) deformable body. The formulation of the equations of motion is based on a continuum theory known as the theory of a Cosserat point. These equations largely preserve the relative simplicity of rigid body dynamics but incorporate deformable features. The ease of computer implementation permits the simultaneous simulation of vehicle and collision dynamics of multiple vehicles and highway objects. In this paper, the theory of a Cosserat point is summarized and its general application to vehicle and collision dynamics is illustrated. A three-dimensional collision algorithm is discussed with emphasis on small closing velocities (negligible residual crush, elastic rebound). The novel model is compared to standard procedures.     

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.     

Swimming for survival: A role of phytoplankton motility in a stratified turbulent environment

We investigate a role for vertical migration in stratified coastal water, where the swimming speed is generally significantly less than the typical turbulent fluctuations in a tidally-mixed bottom layer. In our modelling approach we use a k- turbulence model to describe the physical forcing, a Lagrangian random walk model to describe the vertical displacement of individual cells in response to turbulence and due to cell motility, and a phytoplankton growth model to direct the swimming behaviour of the phytoplankton according to their light and nutrient requirements. The model results show how the cells form a stable subsurface chlorophyll maximum (SCM) at the base of the thermocline where episodic tidal turbulence causes erosion of part of the SCM biomass into the bottom mixed layer (BML). We then focus on the question of whether an ability to swim (weakly, compared to typical bottom layer turbulent intensities) provides any advantage by allowing return to the SCM. Our results show that tidal turbulence in the BML helps both motile and neutrally-buoyant cells by periodically pushing them into the base of the thermocline. Motile cells then have the advantage that they can swim further into the thermocline towards higher light which also reduces the likelihood of being re-mixed back into the BML.     

Cost-minimizing retrofit/replacement strategies for diesel emissions reduction

The cost effectiveness of various emission reduction diesel retrofits is analyzed, as is early vehicle retirement. An integer program is developed to find cost-minimizing cleanup strategies, given reduction goals for various pollutants, as well as technological and budget constraints. Retrofits are assumed to take place in the present, but benefits and costs can be distributed over time. Budget constraints deal with short-term expenditures, while the overall objective is to minimize the net present value of short and long-term costs. The model is intended as a tool both for fleet owners and for government administrators. A case study examines the potential to clean up a diesel school bus fleet.     

雷诺全新一代旗舰重卡T系列的千里试驾

相对轻型的11 L发动机与Sleeper型号驾驶室的匹配已经足够替代上一代的Premium系列重卡;而对于长途运输,Top Sleeper驾驶室将会是最佳的选择,融合了瑞典技术并继承了法国车所特有的属性,使其成为高端重卡市场的不二选择。