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251.
Warren B. Powell 《Transportation Research Part B: Methodological》1982,16(1):31-43
Variability in the demand for air travel is studied with respect to stochastic and time varying components which affect the distribution of passengers who will want to travel on a particular day. The problem is then cast as one of optimizing the total capacity offered in a given time period using operating net revenues as the objective. The distribution of demand is assumed to be normal, and passengers lost on those days when demand is high are assumed to travel on another airline or a different mode. An airline must therefore balance the costs of increased capacity against the benefits of carrying more people. Tradeoffs are studied parametrically, with particular emphasis on the effect the variance of the distribution of demand has on different relationships. Also shown is a simple procedure for estimating actual market mean and variance given the mean and variance of the number of passengers actually flown, which has a truncated distribution. 相似文献
252.
B. Nolan 《Maritime Policy and Management》1976,4(2):77-88
Drinking among seafarers is an age-old and insufficiently studied problem. This paper is not concerned with alcoholism but with normal social drinking, its effects on suicide and accident rates, and its considerable value as an integrating factor in shipboard life. The author distinguishes sharply between sea-drinking and port-drinking and summarizes the research that relates personality traits, particularly dependence, to the use and abuse of alcohol. 相似文献
253.
J. B. Allen 《Maritime Policy and Management》1979,6(1):15-23
The future of waterborne commerce on the Trinity River, Texas, depends on the extent to which the waterborne transport system constitutes a definite cost saving over alternate transportation modes. This paper outlines the results of a study conducted in the area, the purpose of which was to establish potential transportation savings from containerized commodity movements on the Trinity River. 相似文献
254.
255.
Research purposes: In recent years, tunnel diseases like lining cracking and water leaking during spring thawing period, caused by frost heaving of surrounding rock, have occasionally occurred in high-latitude seasonally-frozen regions of northwest China and northeast China, which has seriously affected the tunnel structure and operation safety. Taking several railway tunnels in northwest China as an example, this paper investigates the cause and main influencing factors of longitudinal cracking of side wall in winter in seasonal frozen soil area by means of field test, laboratory experiment and numerical simulation. Research conclusions:(1) When the water content of surrounding rock of tunnel built in strongly-weathered sandstone is 12.3% and the frozen depth of surrounding rock is up to 60 cm, the maximum tensile stress of side walls is 2.28 MPa, which is larger than the ultimate tensile strength of C30 concrete, then the horizontal lining cracking will appear on side walls under the effect of continuous negative temperature in winter. If the lining bears part of the surrounding rock load, the longitudinal cracking degree of the side wall will increase. (2) Under the effect of frost heaving loads, the cracking of tunnel lining has its own characteristics of symmetry, seasonality and accumulation, etc. The cracks appear in winter and distribute in the middle of side walls. As the temperature is rising, the crack begins to shrink. (3) The frozen circle thickness and water content of surrounding rock should be used as main indicators during the process of calculation of frost heaving loads of surrounding rock in seasonally-frozen regions. (4) The research results can be used for reference in tunnel design, operation and maintenance in seasonal frozen soil area. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved. 相似文献
256.
肖生祥 《西安交通大学学报(英文版)》1995,(2)
EXPRESSIONOFPRESROTEINOFHBVASAALKALINEPHOSPHATASEFUSIONPROTEINSINNIH3T3CELLSXiaoShengxiang;T.S.B.Yen(LaboratoryofMolecularPat... 相似文献
257.
隧道衬砌结构可靠指标计算方法的研究 总被引:6,自引:0,他引:6
本文采用有限元-响应面法及Monte-Carlo模拟获得衬砌结构内力的特征参数,并以此为基础,利用五种结构可靠度分析法计算明洞与隧道衬砌结构可靠指标,经对比得出Trym法求出的隧道衬砌结构可靠指标最小,为今后进一步寻求隧道结构设计安全系数与可靠指标之间的对应关系奠定基础。 相似文献
258.
Panel data are used to investigate what happens when people have some important transitions or changes in their life-cycle, employment status, income, or car ownership. Only three years data are available, and the pace of transition is slow: as a result relevant sample sizes are rather small. The analysis is carried out in two stages: results are given from a two year period, and these are used to generate hypotheses checked with data from the third year.It is found that in many cases the effects on mobility are different from what would be expected from cross-section data. In particular:
相似文献
| - car ownership changes are substantially less than expected; |
| - public transport does not benefit as much as expected when people become members specific dependent or captive groups. |
259.
Safety mechanism is required for an automotive battery pack to prevent thermal failure which could lead to catastrophic events. Passively cooled battery packs can prevent thermal failure by conducting adaptive control of battery power without any external cooling device. The key to this power control is how to secure battery safety while minimizing energy loss. This paper proposes a novel, adaptive power control strategy for automotive passive-cooling battery packs. Four different cases with electrochemical battery model are simulated and compared to each other according to a city driving profile. Driving simulation result confirmed that the present power control algorithm is an effective solution for preventing thermal failure along with improving energy efficiency of automotive battery packs. 相似文献
260.
B. M. Duan Q. N. Wang J. N. Wang X. N. Li T. Ba 《International Journal of Automotive Technology》2017,18(2):335-344
This paper presents a calibration method of a rule-based energy management strategy designed for a plug-in hybrid electric vehicle, which aims to find the optimal set of control parameters to compromise within the conflicting calibration requirements (e.g. emissions and economy). A comprehensive evaluating indicator covering emissions and economy performance is constructed by the method of radar chart. Moreover, a radial basis functions (RBFs) neural network model is proposed to establish a precise model within the control parameters and the comprehensive evaluation indicator. The best set of control parameters under offline calibration is gained by the multi-island genetic algorithm. Finally, the offline calibration results are compared with the experimental results using a chassis dynamometer. The comparison results validate the effectiveness of the proposed offline calibrating approach, which is based on the radar chart method and the RBF neural network model on vehicle performance improvement and calibrating efficiency. 相似文献