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排序方式: 共有1516条查询结果,搜索用时 15 毫秒
61.
Byung Hwa Park Nam Po Kim Jung Seok Kim Kang Yong Lee 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(12):887-901
This paper addresses the use of finite-element (FE) analysis to calculate the fatigue strength of a bogie frame, for the development of tilting trains in Korea. A multi-body dynamic analysis was performed to extract the load condition by tilting on curves. Using the results of the multi-body dynamic analysis and the load scenario setout in the UIC standard, FE analysis was performed to obtain the stress distribution and to calculate the fatigue strength. An attempt was made to minimize the weight of the bogie frame using a back-propagation artificial neural network (ANN). The results of this study reveal that the stresses at some nodes are near the fatigue limit in the Goodman diagram and by using back-propagation ANN, the weight of the bogie frame could be reduced by 4.7%. 相似文献
62.
李虎松 《西安交通大学学报(英文版)》1995,(2)
REGULATIONOFPRODUCTIONOFPARATHYROIDHORMONE-RELATEDPEPTIDE(PTHrP)ANDEXPRESSIONOFITSmRNAINAHUMANLIVER-DERIVEDCELLLINELiHusong;P... 相似文献
63.
64.
This paper presents a time-series model for the spot speeds of vehicles on a road section. Based on time-series analysis techniques, the model incorporates information on the extent of existing dependency between the speeds of successive vehicles. The model for the data is chosen while relying heavily on the data, and thus emphasis is given to their special characteristics. The advantages of using the model are examined with regard to the relative speed of two successive vehicles along a road section. The results are compared with those obtained by using a model of independent observations; fewer errors are obtained with the time-series model. Therefore, it is concluded that the sequence of speed observations contains valuable information which should be incorporated into speed models. 相似文献
65.
Patrick S. McCarthy 《Transportation Research Part B: Methodological》1982,16(4):263-278
Current evidence on the transferability of disaggregate travel demand models is inconclusive. Adding to this body of research, the present analysis focuses upon the temporal characteristics of work trip behavior in the San Francisco Bay Area. Using before and after data sets associated with the BART Impact Travel Study, multinomial logit models of work trip modal choice are estimated. The results indicate that the general form and the coefficient estimates of a pre BART model are transferable in time. Moreover, when updated to reflect BART's presence, the model's predictive success and its implied elasticity measures are generally accurate, relative to those implied by reestimating the entire model on post BART data. Finally, as economic theory would predict, elasticity measures of the service related variables were found to increase over time. 相似文献
66.
Yunyoung?Kim Koji?GotohEmail author Masahiro?Toyosada 《Journal of Marine Science and Technology》2004,9(2):70-79
This article considers microgenetic algorithms (GAs), which explore in a small population with a few genetic operators, for cutting-path optimization problems. The major difference between GAs and simple genetic algorithms (SGAs) is how to make a reproductive plan for an improved searching technique because of population choice. It is shown that GAs implementation reaches the near-optimal region much earlier than the SGAs approach, and the GAs give a better solution than simulated annealing (SA). The main objective was to determine what temperature distribution can be obtained from the solution of a travelling distributed heat source. The solution of the travelling heat source on nested raw plate provides information about the vertices of each nested part of the raw plate. From the fact that the initial temperature at a piercing point strongly depends on the heat flow which stems from the previous cutting contour, the temperature of all piercing points must be lower than the critical temperature after each cutting of the components of a part. The critical temperature is identified as the mechanical melting temperature of steels. A heuristic back-tracking method is introduced to find the near-optimum cutting path considering the minimum heat effect on deformation. The heuristic back-tracking method is incorporated with the GAs. 相似文献
67.
68.
D. B. Sonawane K. Narayan V. S. Rao S. C. Subramanian 《International Journal of Automotive Technology》2011,12(5):697-704
Most commercial vehicles such as buses and trucks use an air brake system, often equipped with an S-cam drum brake, to reduce
their speed and/or to stop. With a drum brake system, the clearance between the brake shoe/pad and the brake drum may increase
because of various reasons such as wearing of the brake shoe and/or brake drum and drum expansion caused by high heat generation
during the braking process. Hence, to ensure proper functioning of the brake system, it is essential that the clearance between
the brake shoe and the brake drum is monitored. In this paper, we present a mathematical model for the mechanical subsystem
of the air brake system that can be used to monitor this clearance. This mathematical model correlates the push rod stroke
transients and the brake chamber pressure transients. A kinematic analysis and a dynamic analysis of the mechanical subsystem
of the air brake system were performed, and the results are corroborated with experimental data. 相似文献
69.
This papers examines the different choices of High Speed Craft (HSC) hull design available and briefly looks at the advantages and disadvantages of each hull form. The trends in various design aspects of HSC such as speed, capacity and size are studied. An investigation on the HSC development is conducted and the future of HSC in the UK is studied. A study onboard an HSC with the aim of trying to determine what passengers think of HSC and why they travel by them is also conducted. Finally, an analysis of the possible market for HSC is carried out. 相似文献
70.
Compression ratio (CR) is a design parameter with highest influence on efficiency, emission and engine characteristics. In conventional internal combustion (IC) engines, the compression ratio is fixed and their performance is, therefore, a compromise between conflicting requirements. One fundamental problem is that drive units in the vehicles must successfully operate at variable speed and loads and in different ambient conditions. If a diesel engine has a fixed CR, a minimal value must be chosen that can achieve a reliable self-ignition when starting the engine in cold start conditions. In diesel engines, variable compression ratio (VCR) provides control of peak cylinder pressure, improves cold start ability and low load operation, enabling the multi-fuel capability, increase of fuel economy and reduction of emissions. By application of VCR and other mechanisms, the optimal regime fields are extended to the prime requirements: consumption, power, emission, noise, etc., and/or the possibility of the engine to operate with different fuels is extended. An experimental Diesel engine has been developed at the Faculty of Engineering, University of Kragujevac. The changes of CR are realized by changing the piston chamber diameter. Detailed engine tests were performed at the Laboratory for IC engines. Special attention has been given to decrease of fuel consumption and exhaust emissions. An optimal field of CR variation has been determined depending on the given objectives: minimal fuel consumption, minimal nitric oxides, and particulate matter emissions, etc. 相似文献