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151.
This paper is the second invstigation on the effect of fuel stratification on flame propagation. In the previous work, the
characteristics under the no port-generated swirl condition, i.e., the conventional case was studied. In this work, the flame
development under the low swirl condition was considered. For this purpose, the initial flame development and propagation
were visualized under different axially stratified states in a modified optical single cylinder SI engine. The images were
captured by an intensified CCD camera through the quartz window mounted in the piston. Stratification was controlled by the
combination of the port swirl ratio and injection timing. These were averaged and processed to characterize the flame propagation.
The flame stability was estimated by the weighted average of flame area and luminosity. The stability was also evaluated through
the standard deviation of flame area and propagation distance and through the mean absolute deviation of the propagating direction.
The results show that the flame-flow interaction determines the direction of flame propagation and that the governing roles
of the two factors vary according to the stratified state and the location in the cylinder. In addition, the flame development
and the initial flame stability are strongly dependent on the stratified conditions, and the initial flame stability is closely
related to the engine stability and lean misfire limit. Lastly, there is no essential difference in gasoline and CNG flame
propagation characteristics. 相似文献
152.
This paper presents a steering control method for lane-following in a vehicle using an image sensor. With each image frame
acquired from the sensor, the steering control method determines target position and direction, and constructs a travel path
from the current position to the target position either as an Arc-path or S-path. The steering angle is calculated from the
travel path thus generated, and the vehicle follows the travel path via motor-control. The method was tested using a vehicle
dubbed as KAV (Korea Autonomous Vehicle) along an expressway (Seoul Inner Beltway) trajectory with a variety of radii (50
m ∼ 300 m) while traveling at a speed of 60 km/h to 80 km/h. Compared with an experienced human driver, the method showed
little much difference in performance in terms of lane-center deviation. The proposed method is currently employed for high
speed autonomous driving as well as for stop and go traffic. 相似文献
153.
This paper proposes a new neuron control strategy for an active vehicle suspension system, with the emphasis on the study
of multivariable and uncertain suspension characteristics. The novelty of this strategy is in the use of integrated error,
which consists of multiple output errors in the regulated plant. By combining the integrated error approach with the traditional
neuron control (TNC), integrated error neuron control (IENC) is presented. It provides a direct control to the multiple outputs
of the control plant simultaneously. Taking a quarter-car model as an example, the proposed control strategy is applied and
comparative simulations are carried out with various vehicle parameters and road input conditions. Simulation results prove
the effectiveness and robustness of the proposed IENC method. In addition, the newly proposed neuron scheme provides a simple
yet efficient new possibility for the control of a class of uncertain multivariable systems similar to an active vehicle suspension. 相似文献
154.
The impact of high-speed technology on railway demand 总被引:1,自引:0,他引:1
This paper estimates a passenger railway demand function to analyse effects arising from the introduction and use of high-speed
technologies. The paper reports estimates of demand elasticities with respect to price, income, quality of service and a range
of exogenous characteristics. The results show that travel time savings from conventional high-speed technology have a larger
impact on passenger demand than tilting train technology. The introduction of conventional high-speed technology is associated
with an 8% increase in passenger railway demand. Increasing the use of either type of high-speed technology appears to induce
small positive effects on demand beyond those obtained from usual traffic density increases on non-high-speed existing technology.
Antonio Couto is an assistant professor in the Faculty of Engineering (FEUP) at the University of Porto. He received his PhD from FEUP in 2005 having completed a thesis in railway transport economics. His research focuses on issues related to transport economics and infrastructures. Daniel J. Graham is a Reader in the Centre for Transport Studies at Imperial College London. He specialises in the economics of transport, focusing in particular on modelling the implications of transport provision and accessibility for productivity and economic growth. 相似文献
Daniel J. Graham (Corresponding author)Email: |
Antonio Couto is an assistant professor in the Faculty of Engineering (FEUP) at the University of Porto. He received his PhD from FEUP in 2005 having completed a thesis in railway transport economics. His research focuses on issues related to transport economics and infrastructures. Daniel J. Graham is a Reader in the Centre for Transport Studies at Imperial College London. He specialises in the economics of transport, focusing in particular on modelling the implications of transport provision and accessibility for productivity and economic growth. 相似文献
155.
Understanding of the activity-travel patterns of children is becoming increasingly important to various policy makers. Further,
there is also a growing recognition that intra-household interactions need to be explicitly accommodated in travel models
for realistic forecasts and policy evaluation. In the light of these issues, this paper contributes towards an overall understanding
of the school-travel behavior of children and the related interdependencies among the travel patterns of parents and children.
An econometric model is formulated to simultaneously determine the choice of mode and the escorting person for children’s
travel to and from school. The 2000 San Francisco Bay Area Travel Survey (BATS) data are used in the model estimation process.
Empirical results indicate that the characteristics of child like age, gender, and ethnicity, and employment and work flexibility
characteristics of the parents have strong impacts on the mode choice decisions. In addition, the impacts of some of these
attributes on the choice of mode to school are different from the corresponding impacts on the choice of mode from school. The distance between home and school is found to strongly and negatively impact the choice of walking to and from
school, with the impact being stronger for walking to school. Several land-use and built-environment variables were explored,
but were found not to be statistically significant predictors.
相似文献
Sivaramakrishnan Srinivasan (Corresponding author)Email: |
156.
Konstantinos G. Zografos Konstantinos N. Androutsopoulos Teemu Sihvola 《Transportation》2008,35(6):777-795
Flexible transport services include a wide range of demand responsive transport systems that provide non-conventional passenger
and freight transportation services. Several alternative business models varying according to the local market conditions,
the socio-economic, legal, and institutional framework may be developed for the provision of Flexible Transport Systems (FTS).
The objective of this paper is twofold: first to present an integrated methodological framework for developing and assessing
alternative FTS business models and second to demonstrate its applicability to a case study regarding the prioritization of
alternative FTS business models for the provision of flexible passenger transport services in Helsinki.
相似文献
Teemu SihvolaEmail: |
157.
In this paper, we take an initial look at the spatial and temporal flexibility in the activity patterns of the so-called “baby-boomer”
cohort (born 1947–1966) in comparison with younger and older adults. Using a unique longitudinal survey carried in Quebec
City from 2002 to 2005, we explore activity patterns and trip rates over a seven-day observation period during the first wave,
and take a first look at some aspects of their evolution over two subsequent waves at about one-year intervals. We model the
propensity to undertake activities within selected conventional non-work classifications such as “shopping” and “leisure”,
and also according to respondents’ own perceptions of the spatial and temporal flexibility of each out-of-home activity that
they had executed. While we cannot strictly separate cohort effects from age-related effects, after controlling for gender
and household structure, we infer that age and related lifestyle effects dominate in explaining these propensities. However,
the boomers were the only age stratum to increase their total out-of-home activity participation over the course of the panel,
an intriguing starting point for the future study of this cohort.
Luis F. Miranda-Moreno has been recently appointed as Assistant Professor in the Department of Civil Engineering and Applied Mechanics at McGill University. His research focuses on travel behaviour, transportation safety and evaluation of sustainable transport strategies. Martin Lee-Gosselin recently retired as Full Professor at the Graduate School of Planning and CRAD, Université Laval, Québec, and is Visiting Professor at Imperial College London. His research interests are transport and telecommunications behaviour, survey methods, energy efficiency and the impacts of transport on the environment and public health. 相似文献
Martin Lee-GosselinEmail: |
Luis F. Miranda-Moreno has been recently appointed as Assistant Professor in the Department of Civil Engineering and Applied Mechanics at McGill University. His research focuses on travel behaviour, transportation safety and evaluation of sustainable transport strategies. Martin Lee-Gosselin recently retired as Full Professor at the Graduate School of Planning and CRAD, Université Laval, Québec, and is Visiting Professor at Imperial College London. His research interests are transport and telecommunications behaviour, survey methods, energy efficiency and the impacts of transport on the environment and public health. 相似文献
158.
Athanasios A. Pallis 《WMU Journal of Maritime Affairs》2007,6(1):3-20
Throughout Europe, a number of maritime interests have re-targeted their lobbying structures and strategies aiming to influence
the development of the maritime related European Union (EU) policies. The paper examines these maritime interests’ mobilisation
in the making of the Common EU Maritime Transport Policy (CMTP). First, it provides a review of the role of these interest
groups and the implications of the observed collective interests’ representation. Then, with the contribution a data-set of
replies to a questionnaire distributed to all the interest groups that are involved in EU maritime affairs, the paper analyses
the variety of interest groups representing the maritime sector in EU affairs. The focus is on the structures (i.e. membership
numbers and types, location, internal structures, budget) and the lobbying practices of the 37 identified EU level maritime
related organisations. The paper also presents an evaluation of the most positive and most negative parameters of the ‘EU
environment’ and the ‘economic environment’ that assist, or undermine, the governability cohesiveness of this collective action.
This study provides information on whether and under what conditions maritime interests are able to form comprehensive EU-level
organisations capable of representing their members and their interests in the EU policy making process 相似文献
159.
160.
Ships of opportunity have been used to investigate ocean–atmosphere CO2 fluxes in the English Channel and Southern Bight of the North Sea. Continuous underway measurements of the fugacity of seawater carbon dioxide (fCO2sw), chlorophyll, temperature and salinity have been performed along 26 transects during the spring and autumn periods. The spatial fCO2sw distribution along the Channel and Southern Bight is modulated by the photosynthetic activity, temperature changes and water mixing between inputs from the North Atlantic Ocean and riverine discharges. The seasonal variability of fCO2sw is assessed and discussed in terms of the biology and temperature effects, these having similar impacts. The variation of fCO2sw shows similar interannual patterns, with lower values in spring. The annual average of air–sea CO2 fluxes places the English Channel as neutral area of CO2 uptake. The spring and autumn data allow differentiating between distal and proximal continental areas. The Southern Bight shows a tendency towards net CO2 uptake on the distal continental shelf, whereas the Scheldt and Thames Plumes show a CO2 source behaviour on the proximal continental shelves. 相似文献