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A vehicle assignment problem (VAP) in a road, long‐haul, passenger transportation company with heterogeneous fleet of buses is considered in the paper. The mathematical model of the VAP is formulated in terms of multiobjective, combinatorial optimization. It has a strategic, long‐term character and takes into account four criteria that represent interests of both passengers and the company's management. The decision consists in the definition of weekly operating frequency (number of rides per week) of buses on international routes between Polish and Western European cities. The VAP is solved in a step‐wise procedure. In the first step a sample of efficient (Pareto‐optimal) solutions is generated using an original metaheuristic method called Pareto Memetic Algorithm (PMA). In the second step this sample is reviewed and evaluated by the Decision Maker (DM). In this phase an interactive, multiple criteria analysis method with graphical facilities, called Light Beam Search (LBS), is applied. The method helps the DM to define his/her preferences, direct the search process and select the most satisfactory solution. 相似文献
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Application of Sensitivity Methods to Analysis and Synthesis of Vehicle Dynamic Systems 总被引:1,自引:0,他引:1
Andrzej G. NALECZ Associate Professor Research Fellow 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1989,18(1):1-44
The development and application of sensitivity methods for determining the effects of parameter changes on the response of vehicle dynamic systems is presented. The procedures shown can be used to enhance the analysis and synthesis processes of virtually any road or rail vehicle system regardless of its complexity. The parametric sensitivity of vehicle models in time domain, steady state models and vehicle models in frequency domain can be investigated using different types of sensitivity functions, both dimensional and dimensionless including first order standard, percentage, logarithmic, second order standard, and logarithmic and percentage sensitivity measures. These sensitivity functions and measures are determined as functions of partial derivatives of system variables taken with respect to system parameters. In the case of sensitivity functions in the frequency domain the variable values are computed as either the magnitude or phase angle of a complex element of the transfer function matrix. The methods presented enable to determine the influence of all system primary (constant) and secondary (non-constant) parameters on system primary and secondary variables. The primary variables are state variables or elements of the transfer function matrix and the secondary variables may be any functions of primary variables and system parameters. Typical secondary system parameters which can be examined include initial conditions, time variant coefficients, natural frequencies, loads, and typical secondary variables are forces, weight transfers, stability factors and energy components. The analysis of sensitivity results obtained for three vehicle handling models in both linear and nonlinear regimes of vehicle performance and utilizing various types of sensitivity functions is also presented. 相似文献
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Andrzej Maslowski Dr habil. Associate Professor J zef Krutul MSc Senior Researcher 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1984,13(6):357-366
In this paper a method of analysis of vehicle head-on collision, based on the concept of dispersion of stress waves in rods upon axial impact has been presented. The mathematical model of collision studied here described the vehicle behaviour in collision in terms of a one-dimensional, nonhomo-geneous, nonlinear partial differential equation. A procedure of model identification and some remarks concerning experimental data have been discussed. Results of computer simulation of a tested vehicle have been given. 相似文献
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Andrzej G. NALECZ 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1988,17(3):141-163
This paper presents a procedure for determining the sensitivity matrices of a vehicle dynamic system in the frequency domain as derivatives of the transfer function matrix with respect to system parameters. First and second order logarithmic sensitivity functions which possess normalized coefficients have been introduced to enhance analysis. The sensitivity analysis of amplitude-frequency characteristics on changes of selected parameters of a 3 degree-of-freedom vehicle handling model has been performed. It has been demonstrated that the general sensitivity measure proposed can be used to determine the combined influence of system parameters divided into groups such as design, environmental, driver, kinematic, etc., on the multi-parameter system response, prior to determining their order of influence within the groups. 相似文献
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This paper presents theoretical analysis of unconventional forging process of hollowed shaft from Ti-6Al-4V alloy in a three-slide
forging press. This method in comparison with other metal forming methods allows for obtaining of hollowed products. The designed
process is verified theoretically by means of numerical simulations based on finite element method with assumption of 3D state
of strain. The following factors are considered in the analysis: material flow kinematics, strain distribution, temperature
distribution and force of process. On the basis of results, it is stated that the application of designed technology allows
for obtaining of a product of assumed quality. A comparison is made between material consumption in analyzed process and material
consumption in typical metal forming methods, also in used at present technology of shaft manufacturing by machining only.
It is stated that the application of forging in the three-slide forging press allows for a considerable decrease of manufacturing
costs due to material savings and decrease of labor consumption of operations at finishing. 相似文献
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Simulation of Rail Vehicle Dynamics in MATLAB Environment 总被引:2,自引:0,他引:2
Andrzej Chudzikiewicz 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2000,33(2):107-119
The following paper describes a general conception and realization of a computer package to predict some aspects of dynamic behaviour of railway vehicles. The package consists of three parts, an interactive pre-processor, the analysis program and an interactive post-processor. MATLAB was used as environment for the realization of the package. In recent versions only passenger vehicles, which have a MD 52 (Minden-Deutz) type trucks, can be analysed but the pre- and post-processor have a general form. 相似文献
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The paper presents the results of a thermo-mechanical analysis of the rolling two stepped shafts. One of the shafts has a
toothed step with skew teeth, while the other has a worm winding in the shape of a trapezoidal screw. The shape of the rolling
tools resembles that of the tools used in the Roto-Flo rolling method; yet unlike in Roto-Flo, the shafts are hot-rolled and
no centres are used to stabilize the position of the workpiece during the forming process. For the calculations made with
use of the DEFORM-3D process simulation system it has been assumed that the rolled shafts are made from 2618 aluminium alloy.
As a result of the calculations made, it has been found that the toothed stepped shafts can be formed in one pass by means
of the cross rolling process. Additionally, the temperature and strain distribution in the rolled product have been determined
as well as some data concerning the forces which are necessary for the rolling process have been obtained. 相似文献
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本文提出了一种无限深水中表面效应船(Surface Effect Ship,SES)尾波(Wash wave)数值方法.SES的尾波被表达成分布在气垫上的压力在静水中航行产生的兴波波浪场.在线性势流假设下,该尾波可解析地表示为积分形式,而其被积函数带有奇性并高频振荡.文中提出了一个变换,使变换后对不同的航速,SES船形(气垫形状)和所要计算的波浪场位置尾波计算中的被积函数是单调变化,因而易于数值计算.积分中的奇性也予以去除.数值计算结果表明本文提出的数值方法具有较高的计算效率而且结果与已发表的结果吻合良好.文中给出了一些SES船尾波(Wash wave)的计算结果,并进一步分析了SES尾波(Wash wave)中的局部和非局部波浪场成分.文中还尝试使用本文方法预报常规高速双体船的尾波(Wash wave),结果发现预报与水池测量结果相当吻合. 相似文献
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