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771.
Road Surface Correction o f Tire Test Data 总被引:1,自引:0,他引:1
P. Van Der Jagt A.W. Parsons 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1996,25(2):147-165
Most tire data used for vehicle simulations is measured on laboratory test facilities. An investigation showed that the frictional properties of these laboratory machines can be quite different from actual road conditions. This paper describes a method to correct laboratory tire test data to be more like road data in order to achieve a higher degree of correlation between instrumented test- and simulation results. 相似文献
772.
Information from various sources, but most specifically from the YORKSHARE car-sharing schemes, is brought together in an analysis of public reaction to, and participation in, a car-sharing scheme with centralised matching of applicants. The importance of various attributes of the sites, of the individuals and of the scheme organisation are assessed and conclusions are drawn.The motivation of individual participants is analysed and is seen to vary from one person to another depending to some extent on their circumstances, but the universal importance of some features, notably cost savings, is revealed. 相似文献
773.
774.
This paper describes the development of a non-linear, dynamic jack-up analysis method in the time domain. It provides background as to why and when such analysis is required.
The theoretical background of the methods applied are discussed and the main features of the programme are described. 相似文献
775.
Governments of all persuasions are increasingly seeking the participation of the private sector in the supply of transport facilities and services. Private sector participation in the financing, construction, operation and maintenance of infrastructure is considered a serious option in a number of countries in the search for ways of providing much needed investment which would otherwise be deferred. This paper considers some economic and financial problems in the private sector provision of major road infrastructure within urban areas. The main issues are attaching prices (i.e. tolls) to the provision of the service, the value of government rights which are being given up either permanently or temporarily, and the identification required by the promoters of the cost of capital which is essential information in establishing the risk. Broader environmental and equity issues are not addressed. If the approach to establishing a private presence in a previously public supply context is handled properly from the outset, the benefits can be significant. Contrarily however, the prospects could be quite undesirable if badly managed, despite the presence of an extended public purse.requests for offprints 相似文献
776.
Jan A. Berg-Andreassen 《Maritime Policy and Management》1997,24(4):335-350
This paper evaluates empirically some very common theories of the freight rate generating process in the time charter markets. After a review of the most common assumptions made of the way time charter rates are set, the hypotheses are identified as follows: (a) the Zannetos Hypothesis, (b), the Lagged Zannetos Hypothesis, (c) the Koyck Lag Hypothesis, (d) the Rational Expectation Hypothesis, and (e) the Conventional Wisdom Hypothesis. These hypotheses are tested using statistical cointegration analysis that includes both an Augmented Dickey-Fuller (ADF), and a Johansen likelihood ratio test. Confronted with the data, hypotheses (a) and (b) are rejected outrightly. In the Koyck Lag case, the ADF statistic seem to confirm the hypothesis. A closer look at the numbers reveals that all of the impact on the time charter rates comes from the lagged dependent variable. Hence, the Koyck Lag Hypothesis is rejected. In the Rational Expectation case, the two tests conflicted. Based on the fact that the Rational Expectation Hypothesis includes the lagged dependent variable and that the Johansen test has been found to be a more robust test than the ADF test, the Rational Expectation Hypothesis is rejected. The fifth hypothesis is a reflection of the general bulk industry perception that the time charter rate is impacted by changes in the comparable spot rate and not much by the spot rate levels. In this case both the ADF and the Johansen test accepted the hypothesis for all markets. Thus, the paper concludes that the conventional market explanation of the time charter freight rate setting process is essentially correct-spot rate changes matter spot rate levels do not. 相似文献
777.
Collision damage of jack-ups 总被引:1,自引:0,他引:1
North Sea collision accident records covering a period of ten years indicate that the risk of collisions involving jack-ups is not dissimilar to that for semi-submersibles or fixed jacket structures. However, jack-ups are much more flexible than jackets and have a much lower degree of redundancy. Their response to collisions and their ability to absorb impact energy is, therefore, expected to be considerably different in comparison to jackets. This paper examines available data and information regarding the capability of jack-ups to withstand collision impacts and investigates the level of local damage that can potentially be caused to jack-up legs due to accidental collisions. 相似文献
778.
779.
780.
M. A. Lohe R. R. Hullgol 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1982,11(5):283-303
The motion of a train wheelset is investigated using Hopf bifurcation theory. The method takes full account of the nonlinear effects of the flange-rail contact forces which are incorporated in the model; The numerical solution is obtained over a wide range of forward speeds by transforming the bifurcation problem into a regular nonlinear boundary value problem, which is solved by standard methods. This solution is shown to be orbitally, asymptotically stable. The algorithm supplies complete information on the lateral and yaw motions and on the period of oscillation, even for very high forward speeds. 相似文献