TARGETED ACTIVATION OF CD_（8）~（＋） CELLS AND INFECTION OF β_2－MICROGLOBULIN－DEFICIENT MICE FAIL TO CONFIRM A PRIMARY PROTECTIVE

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Influence of rail pressure on a two-stage turbocharged heavy-duty diesel engine under transient operation

The demand for continually improving the transient performance of diesel engines requires higher rail pressure and more efficient turbocharger. Before the test, a two-stage turbocharger with a turbine by-pass valve (TBV) had been matched reasonably with the base engine. In order to reduce smoke emission under the typical 5-second transient process of constant speed and increasing torque, the influence of rail pressure on combustion, emissions and performance characteristics was experimentally investigated. The results showed that the two-stage turbocharger was helpful in improving transient performance. Moreover, the full-stage rail pressure (FSRP) strategies (increasing rail pressure during the whole transient process) could reduce smoke emission when the TBV was closed. However, smoke deteriorated once TBV opening got larger. Then the sectional-stage rail pressure (SSRP) strategies (increasing rail pressure from a pre-set load to 100 % load) were presented under small TBV opening to improve in-cylinder thermal condition. Hence, the air-fuel mixing process was improved at medium and large loads. Then the maximum decline of smoke opacity peak was 56.3 %, which happened under 10 % TBV opening. In addition, fuel consumption of FSRP strategies got worse under larger TBV opening. However, this deterioration situation could be effectively restrained by the utilization of SSRP strategies.     

Interaction of vehicle and steering system regarding on-centre handling

For the on-centre handling behaviour of vehicles the steering system is absolutely important. To investigate the interaction of the vehicle and steering system a validated, especially tailored simulation model was developed. Some meaningful vehicle and steering system parameters are altered to show the influence on steering wheel torque, steering feel and understeer. The results underline the importance of an accurate steering system model. Identified measures to improve the centre feel and steering response were a stiffer torsion bar, a higher cornering stiffness or a lower overall steering ratio. The steering response, however, suffers when the centre feel is improved by a higher trail. The steering rack friction reduces mainly the steering response while the steering column friction decreases the centre feel whereas a stiffer torsion bar lessens the understeer tendency.     

Defining and understanding trip chaining behaviour

Trip chaining is a phenomenon that we know exists but rarely investigate. This could be attributed to either the difficulty in defining trip chains, extracting such information from travel diary surveys, the difficulty in analysing all the possible trip chain types, or all of the above. Household travel diary surveys provide a wealth of information on the travel patterns of individuals and households. Since such surveys collect all information related to travel undertaken, in theory it should be possible to extract trip-chaining characteristics of travel from them. Due to the difficulty in establishing and analysing all of the possible trip chain types, the majority of research on trip chaining has appeared to focus on work travel only. However, work related travel in many cities does not represent the majority of activities undertaken and, for some age groups, does not represent any travel at all. This paper begins by reviewing existing research in the field of trip chaining. In particular, investigations into the definitions of trip chaining, the defined typologies of trip chains and the research questions that have been addressed are explored. This review of previous research into trip chaining facilitates the following tasks: the identification of the most useful questions to be addressed by this research; defining trip chaining and associated typologies and defining data structures to extract trip chaining information from the household travel surveys conducted in metropolitan Adelaide, South Australia. The definition and typology developed in our research was then used to extract trip-chaining information from the household travel diary survey (MAHTS99) conducted in Adelaide in 1999. The extracted trip chaining information was then used to investigate trip-chaining behaviour by households. The paper reports the results of this analysis and concludes with a summary of the findings and recommendations for further investigations.     

Deregulation of inter‐city coach services in Britain

Public transport in Britain has traditionally operated under conditions of regulation. The 1930 Road Traffic Act imposed controls upon the quantity and quality of transport regulations, with an abolition of the quantity controls associated with inter‐city coach services. The principal objectives of the Act were to eliminate restriction upon entry to the market and to promote competition between coach operators.

This paper is based on research which was undertaken to establish the impact of the 1980 Transport Act upon express (inter‐city) coach services in Britain. The effects of the legislation are examined in relation to the experience of various coach operators, British Rail, and the inter‐city traveller. This provides evidence of the way in which the supply of, and demand for, public transport behaves in a competitive, deregulated environment. It is shown that at least in net terms, the consumer has enjoyed short‐term benefits. Greater uncertainty surrounds the long‐term situation. The main competition has been confined to the principal trunk routes and has taken place between the state‐owned undertaking of National Express and British Rail. The outcome of deregulation for the private sector has been disappointing.

The paper identified similarities which exist between inter‐city and local public transport services. In this context, the lessons derived from express deregulation are employed to suggest likely developments in the deregulation of stage carriage (local) services in Britain.     

Exposure to noise inside transit buses in Kuwait: Measurements and passenger attitudes

Noise levels were measured, for the first time, inside 115 randomly selected transit buses, operating on 12 sample representative routes in Metropolitan Kuwait. Simultaneously with the monitoring of noise levels, the attitudes of 679 riders concerning the annoyance and long-term health impacts of noise were also surveyed. The noise and passenger attitude data were collected over 10 months (March - December 2000). The percentile distribution, equivalent noise level, traffic noise index and noise pollution levels inside four types of transit buses are presented. Riders' perceived annoyance and awareness of the long-term health impacts of noise were also determined and are discussed. The level of service and performance deficiencies of the public transit system in Kuwait, as perceived by its passengers, are also identified. A number of recommendations end the paper.     

Recreation Conflict Along New York's Great Lakes Coast

This study used goal interference theory to examine the recreation conflict among motorboat users, personal watercraft users, and riparian landowners. Data were collected from three types of owners in the New York Great Lake coastal area. Results indicated each of the four recreation conflict dimensions proposed in goal interference theory contained multiple factors. Logistic regression models indicated that one or more dimensions were significant in predicting perceived conflict and the models correctly predicted conflict in over 70% to 100% of the cases. Goal interference theory can be seen as a general model, but significance of the four dimensions depends on types of recreation activities and users.     

Labour market effects in assessing the costs and benefits of road pricing

Traffic congestion and the policies used to combat it have been studied extensively. One area which has received less attention is the secondary impacts of such policies. This paper uses a micro-simulation framework to study the effect on labour markets of road pricing. The key benefit of our chosen methodology is that it allows a simultaneous consideration of both commuting and migration decisions. We show that while welfare gains can be achieved through optimal charging, this may come at the price of decreased integration. This may manifest through either greater centralisation tendencies in population, or through unemployment disparities between regions.     

Local environmental management—can it work? A case study of the Virginia Wetlands Act

Abstract

The Virginia Wetlands Act of 1972 provides the localities of Tidewater Virginia an opportunity to participate in the management of the state's coastal wetlands resources. This study attempts to analyze the effectiveness of this legislation and to examine the implications of a local management scheme for coastal resource management on a broader scale. Criteria are also established that can be used to evaluate the effectiveness of such a law. When examined in the light of these criteria, the Virginia Wetlands Act emerges, for the most part, as an effective piece of environmental quality legislation that has had a significant impact on wetlands destruction in the state of Virginia. During the two‐year period following the passage of the Act, wetlands losses through the permitting process showed an 18‐fold decrease from previous estimates. The Wetlands Act appears to have been generally accepted by the public and has resulted in consistently uniform decisions, which have reduced wetlands losses without unduly restricting the necessary and legitimate development of the state's wetlands.