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41.
An Alternative Method to Determine the Magic Tyre Model Parameters Using Genetic Algorithms 总被引:2,自引:0,他引:2
J. A. Cabrera A. Ortiz E. Carabias A. Simon 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2004,41(2):109-127
Summary Tyre behavior plays an important role in vehicle dynamics research. Knowledge of tyre properties is necessary to properly design vehicle components and advance control system. For that purpose mathematical models of the tyre are being used in vehicle simulation models. The Magic Formula Tyre Model is a semi-empirical tyre model which describes tyre behavior quite accurately. The Magic Formula Tyre Model needs a set of parameters to describe the tyre properties; the determination of these parameters is dealt with in this paper. A new method based on genetic techniques is used to determine these parameters. The main advantages of the method are its simplicity of implementation and its fast convergence to optimal solution, with no need of deep knowledge of the searching space. So to start the search, it is not necessary to know a set of starting values of the Magic Formula parameters. The comparison between analytical optimization methods and the method proposed is discussed in this paper. 相似文献
42.
Alfonso M. Panunzio G. Puel R. Cottereau S. Simon X. Quost 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2017,55(3):399-426
This paper describes the construction of a stochastic model of urban railway track geometry irregularities, based on experimental data. The considered irregularities are track gauge, superelevation, horizontal and vertical curvatures. They are modelled as random fields whose statistical properties are extracted from a large set of on-track measurements of the geometry of an urban railway network. About 300–1000 terms are used in the Karhunen–Loève/Polynomial Chaos expansions to represent the random fields with appropriate accuracy. The construction of the random fields is then validated by comparing on-track measurements of the contact forces and numerical dynamics simulations for different operational conditions (train velocity and car load) and horizontal layouts (alignment, curve). The dynamics simulations are performed both with and without randomly generated geometrical irregularities for the track. The power spectrum densities obtained from the dynamics simulations with the model of geometrical irregularities compare extremely well with those obtained from the experimental contact forces. Without irregularities, the spectrum is 10–50?dB too low. 相似文献
43.
A new procedure for generating optimal transport strategies has been applied in nine European cities. A public sector objective
function which reflects concerns over efficiency, environmental impact, finance and sustainability is specified and a set
of policy measures with acceptable ranges on each, identified. Optimal strategies based on combinations of these policy measures
which generate the optimal value of the objective function, are identified, and compared between cities. Resulting policy
recommendations are presented. The results demonstrate the importance of an integrated approach to transport strategy formulation.
They emphasise the role of changes in public transport service levels and of fares, and of charges for car use. By contrast,
new infrastructure projects are less frequently justified. In the majority of cities the revenues from car use charges are
sufficient to finance other elements in the strategy. However, private sector involvement either in initial financing or in
operation may be desirable. Revised objective functions to reflect private sector involvement are specified, and optimal strategies
with private sector operation of public transport are also identified. The requirement to meet private sector rates of return
for public transport operation typically results in lower frequencies and higher fares; charges for car use then need to be
raised to satisfy public policy objectives, but system performance is reduced.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
44.
Abstract This article investigates the role of bus rapid transit as a tool for mitigation of transport‐related carbon dioxide (CO2) emissions. We analyse a Quality Bus Corridor (QBC) implemented in Dublin, Ireland, in 1999 and estimate CO2 emissions associated with differing levels of bus priority for the period 1998–2003 and for the Kyoto commitment period (2008–12). Associated monetary values are established using CO2 prices from the European Union Emissions Trading Scheme. We find that, in the absence of a QBC, peak‐time emissions for our sample population would have been 50% higher than in the factual scenario. For the Kyoto commitment period, we find the median value of the policy implementation to be in the region of [euro]650 000. 相似文献
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