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991.
Abstract Road freight transportation has increased dramatically over recent years along with its impacts such as congestion, noise, and pollution. As a result, European and US governments have started policies to promote alternatives to road transportation, such as logistic chains containing a Short Sea Shipping (SSS) link. Road is, by definition, a more flexible means of transportation than shipping, which is usually cheaper. Therefore, to move traffic to SSS chains, it is necessary to provide fast, frequent, and reliable maritime transportation. In this sense, roll-on/roll-off (RoRo) vessels are the most convenient ships to be used, since they have smaller dwell times in port and, therefore, this is a kind of traffic likely to increase dramatically. The foreseeable increase of this kind of traffic must meet with an increase in the actual capacity by means of either improvement in performance and possible enlargements of existing terminals or the construction of new terminals. In that sense, this paper proposes a simple methodology to calculate the capacity of a RoRo terminal, whether already in operation or during its design process, and relate it to some quality standards by means of quality indicators, which should lead to the definition of Levels of Service similar to those already used in roads and airports. The paper ends by applying the methodology to a real terminal in Barcelona, Spain. 相似文献
992.
ABSTRACT Two new detection algorithms, single-station DV (dual-variable) and dual-station CODE (COmbined Detector Evaluation) were developed earlier using 160 incidents collected along Singapore's Central Expressway (CTE). The transferability of these CTE-developed algorithms is assessed, as a case study, using 100 incidents collected from the Tullamarine Freeway and South Eastern Freeway in Melbourne, Australia. The investigation covers the differences in traffic detector systems (loop detectors versus video-based), road geometry and behaviour between drivers in Singapore and Australia. The re-calibrated application of these algorithms to freeways in Melbourne yielded a reasonably good detection performance as well as satisfying the average expected performances of seven traffic management centres surveyed in the USA. The results suggested that the detection logic of the algorithms developed for CTE possessed reasonably good transferability and are also suitable for receiving traffic inputs from video-based detectors as well as from loop detectors. 相似文献
993.
Abstract This study employs the directional graph distance function and the multiactivity data envelopment analysis (DEA) approach, which incorporates both desirable and undesirable outputs, in order to provide a more complete representation of the multimode bus production technology from which environmentally and risk-sensitive cost effectiveness measures can be generated. We treat accident cost as the risky output in the sense that we wish to increase desirable outputs and decrease risky output and inputs. The approach is applied to the problem of measuring the cost effectiveness of 24 bus companies in Taiwan. An empirical illustration suggests that the overall cost effectiveness rankings turn out to be very sensitive to whether or not the graph multiactivity DEA approach is adopted. This implies that the conventional DEA cost effectiveness measure may be seriously misleading if it ignores the cost effectiveness of organizations that carry out various activities whilst sharing common resources. 相似文献
994.
High-speed rail operations have the potential to reduce the long-term decline in rail passenger travel demand for the medium to long distance inter-urban markets. Such decline has been evident through most of the industrialized countries where air and road transport tend to be the dominant modes. In China, the operations of long distance high-speed rail on fully dedicated track is not very easy to implement, due to the high proportion of passengers who travel between high-speed and conventional railways. An alternative approach would be to allow for mixed operations with trains of various speeds on the same track. This article puts forward a simulation model designed to allow an evaluation of the most efficient distance for high-speed rail operations under mixed train speed scenarios. The model takes into account the main operating parameters such as passenger volumes, train speeds, capital and maintenance costs, train operating costs and energy consumption. The distance of high-speed train running on conventional rail that will yield the most economic benefit can be estimated using the model. The article includes the results of using the model for a specific example. It is concluded that large-scale high-speed trains have the potential to be successfully operated on conventional rail networks. 相似文献
995.
A moving sidewalk system installed at an airport pier finger is analyzed. The optimal length of the moving sidewalk and the optimal spacing between the access points which minimize the total cost of the system are obtained using methods of calculus, for a number of cases based on the different proportions of arriving, departing and transferring passengers and for two different types of moving sidewalks: elevated, at‐grade. The optimal length of the moving sidewalk is shown to be linearly related to the length of the concourse, and to the total passenger demand. The effect due to preticketed transferees is insignificant. The optimal spacing between access points is shown to be proportional to the square‐root of either the cost of an access escalator or the cost of inconvenience to a passenger due to an intermediate gap, depending on the moving sidewalk system under consideration. It also changes with the percentage of preticketed transferees. 相似文献
996.
997.
The soot morphological study and NOx emissions of soybean oil methyl ester (SME) in a passenger diesel vehicle were investigated experimentally. The soot morphological characteristics were conducted at various injection pressures, engine speeds and engine loads. Soot sampling and image processing analysis with a scanning electron microscope (SEM) were used to investigate the influence on particulate morphologies. The dimensions of average primary particles and the size of the radius of gyration were gradually decreased as injection pressures increased at all operating engine conditions. The average radius of gyration was increased with increasing engine load, while the average primary particle size decreased. NOx emissions were gradually increased with the increasing injection pressure at all operating engine conditions. 相似文献
998.
S. Yu H. Choi S. Cho K. Han K. Min 《International Journal of Automotive Technology》2013,14(2):175-182
Emission regulations are becoming more stringent and remain a principal issue for vehicle manufacturers. Many engine subsystems and control technologies have been introduced to meet the demands of these regulations. For diesel engines, combustion control is one of the most effective approaches for reducing not only engine exhaust emissions but also cylinder-by-cylinder variation. However, the high cost of pressure sensors and the complex engine head design for additional equipment present difficulties for manufacturers. In this paper, cylinder pressure-based engine control logic is introduced for a multi-cylinder high speed direct injection (HSDI) diesel engine. The time for 50% of the mass fraction to be burned (MFB50) and the IMEP are valuable for determining the combustion status. These two in-cylinder quantities are measured and applied to the engine control logic. Fuel injection timing is controlled to adjust the operating MFB50 to the target MFB50 using PID control logic, and the fuel injection quantity is controlled to adjust the measured IMEP to the desired IMEP. The control logic is demonstrated at steady state and during transient conditions and is applied to an NEDC mode test. 相似文献
999.
A Selective Catalytic Reduction (SCR) system simulation model for diesel engines was established based on MATLAB/Simulink. The model includes four subsystems: signal acquisition, DEF (Diesel Exhaust Fluid) dosing control, catalytic chemistry reaction and NOX emissions reduction. The SCR control strategy was optimized based on ETC simulation results. Simulation and test results indicate that the model developed in this paper can predict ETC NOX emissions accurately. 相似文献
1000.
The purpose of this study is to present a simulation-based approach capable of predicting the fatigue life of a mold core with the help of CAE technology based on injection molding simulation, core stress analysis and fatigue life prediction. Injection molding simulation is performed in order to obtain the non-uniform pressure acting on a mold core due to the polymer melt flow during injection molding process. Subsequently, the melt pressure profile is used as loading condition for core stress analysis via one-way coupling technique. The lifetime of a mold core is then predicted by fatigue analysis with stress-life approach. For verification of simulation-based approach to the fatigue life prediction, tests were also performed. 相似文献