Competition among selected eastern Canadian ports for foreign cargoes

This paper examines the competitiveness of selected eastern Canadian ports for the handling of foreign cargoes in terms of macroeconomic and geographic factors.     

Techniques of land use/transportation planning in Australian cities

With the publication of the Sydney Area Transportation Study, land-use/transportation studies now have been conducted in all capital cities as well as in the majority of other urban areas with populations in excess of 40.000. A review of these studies is made and a qualitative assessment is attempted of the technical phases —land-use planning, trip-generation, trip-distribution, modal-split, traffic assignment and evaluation. Full summary results of this comparative survey are presented in tabular form, although themes developed in the text are illustrated with specific examples from individual studies. The methodology of land-use/transportation studies has been attacked by some Australian writers. An attempt is made to assess the relevance of these criticisms when applied to the practical planning process in Australia.     

Testing and Analysis Techniques for Safety Assessment of Rail Vehicles: The State-of-the-Art

The methods currently being used in North America, Britain and Europe for the safety assessment of rail vehicles are discussed. There is considerable disparity between the methods that have been developed in the different countries. These differences, and the possible reasons for them, are discussed in the paper. Finally, conclusions are drawn and some recommendations are made for the future direction of safety assessment methods.     

The growth of fleets registered in the newly-emerging maritime countries and maritime crises

This paper suggests the existence of a feedback relationship between the dynamic entrance of less-developed countries in shipping and the prolongation and deepening of maritime crises. The duration and extent of the transitional period of crisis depends also on the specific terms of the 'succession' procedure between fleets with different cost levels. During the last major maritime crisis, nations at a less advanced stage of development entered the maritime industry producing a service that had become—more or less—'standardized', following the Vernon product cycle more than all other cycles. The distribution of world tonnage among the different groups of countries underwent major changes as the effects of the economic crisis after 1973, which coincided with developments in the supply of tonnage, created favourable conditions for the rise of the lower cost fleets of developing countries, in a feedback relationship. The restoration of freight levels during the late 80s and early 90s, which was accompanied by a certain stabilization in the various groups of countries' shares in the world fleet, corroborates from the opposite direction the hypothesis of a close interrelationship between maritime crisis and changes in the international hierarchy in shipping.     

Risk and investment decisions in non-liner shipping

The investment decisions of non-liner shipping firms based on their behaviour towards risk, stochastic demand for capacity, inelastic supply and foregone profits are discussed. These aspects are formalized in a simple stochastic model, which, together with definitions of two broad categories of risk behaviour, is then used to examine and contrast the investment decisions of the two different strategic groups. The analysis shows that the capacity expansions/investments sought by the risk averter and the risk lover will differ under 'normal' circumstances with the risk averter having significantly less capacity than the risk lover. The risk lover will have higher capacity in a volatile market than in a stable market situation. During periods of high capital costs, the investment decisions of the two risk groups tend to be indistinguishable.     

Automatic control of clutches and simulations for parallel hybrid vehicles

This paper is a continuation of a previous paper titled ??Modeling and Model Predictive Control for Hybrid Vehicle?? published on IJAT/2011 describing a mathematical model and design for a model predictive controller for tracking speeds and simulations. The present paper further describes a fuzzy logic controller for the smooth and quick engagement of an automatic clutch. The described controller uses both fuzzy logic and slip control algorithms to enable automatic clutch engagement. Clutch engagement and comprehensive simulations for the hybrid vehicle are conducted in MATLAB R2009s. The research described herein offers theoretical solutions for how to better control clutch slip and engagement within realistic parameters used for hybrid vehicles. Algorithms and operations of this fuzzy logic controller can be implemented in electronic control units for automatic clutch engagements and gear-shifting processes.     

Automobile aerodynamics influenced by airfoil-shaped rear wing

Computational model is developed to analyze aerodynamic loads and flow characteristics for an automobile, when the rear wing is placed above the trunk of the vehicle. The focus is on effects of the rear wing height that is investigated in four different positions. The relative wind incidence angle of the rear wing is equal in all configurations. Hence, the discrepancies in the results are only due to an influence of the rear wing position. Computations are performed by using the Reynolds-averaged Navier-Stokes equations along with the standard k-ε turbulence model and standard wall functions assuming the steady viscous fluid flow. While the lift force is positive (upforce) for the automobile without the rear wing, negative lift force (downforce) is obtained for all configurations with the rear wing in place. At the same time, the rear wing increases the automobile drag that is not favorable with respect to the automobile fuel consumption. However, this drawback is not that significant, as the rear wing considerably benefits the automobile traction and stability. An optimal automobile downforce-to-drag ratio is obtained for the rear wing placed at 39 % of the height between the upper surface of the automobile trunk and the automobile roof. Two characteristic large vortices develop in the automobile wake in configuration without the rear wing. They vanish with the rear wing placed close to the trunk, while they gradually restore with an increase in the wing mounting height.     

出行方式与出发时间联合选择的分层Logit模型

基于随机效用最大化理论, 选取出行者特征、行程特性与出行方式服务水平作为效用变量, 以出行方式与出发时间作为选择肢, 构建了出发时间位于下层与出行方式位于下层的2种居民出行NL模型。分析了北京市居民出行样本数据, 并模拟了在早高峰时段对小汽车出行收取费用时, 小汽车出行者出行行为的变化。计算结果表明: 与传统MNL模型相比, NL模型具有更好的统计学特征, 调整后的拟合优度由0.338增大至0.404;在2种NL模型中, 出发时间位于下层的结构对样本数据的适应性更强; 当早高峰时段小汽车出行收取费用为5元时, 72.6%的小汽车出行者坚持原有出行方式与出发时间, 22.4%的小汽车出行者坚持小汽车方式, 但会改变出发时间, 4.8%的小汽车出行者改用公共交通方式, 但出发时间不变, 仅0.2%的小汽车出行者同时改变出行方式与出发时间; 当收取费用为10元时, 51.7%的小汽车出行者坚持原有出行方式与出发时间, 40.4%的小汽车出行者坚持小汽车方式, 但会改变出发时间, 7.9%的小汽车出行者改用公共交通方式, 但出发时间不变; 当收取费用为20元时, 27.5%的小汽车出行者坚持原有出行方式与出发时间, 60.6%的小汽车出行者坚持小汽车方式, 但会改变出发时间, 11.9%的小汽车出行者改用公共交通方式, 但出发时间不变。     

Approximations to the magic formula

Pacejka’s tire model is widely used and well-known by the automotive engineering community. The magic formula describes the brake force, side force and self-aligning torque in terms of the longitudinal slip and slip angle, plus several corrections. This paper uses approximation theory to obtain different types of approximations to the magic formula: rational functions (RA) resulting from the Remez algorithm, expansions in a series of Chebyshev polynomials (ACh), a series of Chebyshev rational polynomials (ARChPs), a series of rational orthogonal functions (ORF) and a series of ARChPs that result from grade-1 ORFs. The last expansion shows the fastest convergence and most effective computation. Jacobi rational polynomials can also be obtained to complement this expansion and facilitate fine-tuning in specific areas of the error curve. This work is complemented by obtaining the original rational approximations to the inverse tangent function, which take advantage of the curve symmetry to reduce the computation load and provide models that include the influence of the vertical load. The convergence properties of the development in series and the error values resulting from numeric examples for the three types of stress are shown. The proposed final ARChP expressions show very low error (1%) compared to the original magic formula. They can be computed 20 times faster; they can be evaluated, derived and integrated analytically easily; and their coefficients can be obtained from tests using common least-squares algorithms.