Shape Optimization of Elliptical Road Containers Due to Liquid Load in Steady-State Turning

A numerical analysis of liquid load in elliptical road containers undergoing a steady-state turning manoeuvre is presented for containers of unrestricted size and for containers of fixed capacity. The liquid load is expressed in terms of the horizontal and vertical forces and the overturning moment created by these forces around the middle bottom point of the container. The moment is obtained by integrating the liquid free-surface equation and using numerical calculation of the resulting expressions. An optimization study with an objective to minimize the peak overturning moment is performed on containers of fixed capacity to identify the optimal height/width ratio of the container. The results of this investigation being of a general nature, i.e. with no restriction for an application, are particularly intended for road tankers under a steady turning manoeuvre, where they can be applied with high degree of accuracy.     

Dynamics of Tracked Vehicles

This paper provides a brief review of the state-of-the-art of tracked vehicle dynamics, including mobility over soft terrain, ride dynamics over rough surfaces and manoeuvrability. It is found that considerable progress has been made in the development of analytical frameworks for evaluating and predicting tracked vehicle mobility over soft terrain, taking into account the characteristics of terrain response to normal and shear loading. Certain computer simulation models for tracked vehicle mobility have been gaining increasingly wide acceptance by industry and governmental agencies in product development and in procurement. It is also found that most of the research on tracked vehicle ride dynamics and manoeuvrability is confined to operations on rigid surfaces. To achieve a realistic evaluation and prediction of the dynamic behaviour of tracked vehicles in the field, the key is to have a better understanding of terrain response to dynamic vehicular loading, including its dynamic stiffness and damping. Challenges that face vehicle dynamicists in this emerging field are identified.     

In-plane Dynamics of Tires on the Road Based on an Experimentally Verified Rolling Ring Model

The dynamic behavior of tires rolling on the road is predicted based on a ring model that is experimentally verified to well represent a real tire. The road contact is kinematically represented by two displacement constraints, one in radial and one in tangential direction. The displacement constraints are enforced via the receptance theory. The receptance matrix developed for the rolling tire is found to be Hermitian. Numerical results show that the natural (or eigen-) frequencies of the rolling tire with road contact are, as expected, higher than those of the tire with no contact. The influence of the rotating speed to the eigen-frquencies of the tire is also shown. Analytic expressions for the mode shapes of a rolling tire with ground contact are derived.     

Experimental Characterization of Damping Force in Shock Absorbers with Constant Velocity Excitation

For the characterization of shock absorbers, which are intrinsically non-linear, it was considered advisable to use the 3D representation of force vs velocity-displacement domain rather than traditional force vs velocity or force vs displacement. Experimental apparatus was therefore designed and constructed to measure the damping force produced by shock absorbers. Data were processed with software suitable for fitting the experimental data functions of several variables. Experiments showed that 3D representation of restoring force allows the non-linearity of shock-absorber damping to be examined more thoroughly.     

Intra-Platoon Collision Behavior during Emergency Operations

This paper presents current research regarding intra-platoon collision dynamics for rapid decelerations. Measures of ride quality and impact severity are introduced to allow comparisons between different collision scenarios. In this study, the disturbance input to the platoon is assumed to be a rapid braking of the lead vehicle. Several deceleration rates are used to assess the overall platoon behavior and the effect of the intra-platoon collisions on the platoon passengers. The role of the desired headway spacing on preventing the occurrence of intra-platoon collisions and improving rider comfort is discussed.     

Leadership and Commitment in the Royal Navy ☆

What is proposed here is a relatively simple procedure by which a fleet manager may select the best mix of ships to provide a given transport service. The method is confined to non-liner trades and assumes the availability of more than enough suitable ships. It further assumes that unneeded ships can be placed in idle status (or returned to owner if chartered in) without penalty.

The objective of the procedure is to select the mix of available ships and sea speeds that can perform the required service at maximum profitability to the owner.     

Fuzzy Control of Clutch Engagement for Automated Manual Transmission

This paper presents a fuzzy control system for the clutch engagement of an automated manual transmission. The servomechanism is assembled with a three-port pneumatic pressure-proportional valve and a position-sensing cylinder which control the release-lever displacement of 25 mm within the position preciseness of 0.1 mm against maximum spring load of 2kN. The fuzzy system is skillful to estimate the driver's will from the accelerator pedal operation. The servomechanism is mounted on a commercial vehicle with 4-ton pay-load. The system parameters are set up by bond graphs simulation and empirical performance tests are carried by using an oil-hydraulically operated engine-vehicle testing rig with a maximum torque capacity of 400 Nm.     

Advanced Control Methods for Automotive Applications

This paper reviews key developments in applications of advanced control methods to automotive systems. Such applications appear in many aspects of vehicle controls. We will examine representative application areas, which include engines, suspension systems, traction systems, steering systems and those for automated highway systems (AHS). Each area is examined from the viewpoint of modeling and control algorithm development. Useful control theories for automotive application are briefly reviewed for better understanding of the applicability of these theories.     

Direction dependent prices in public transport: A good idea? The back haul pricing problem for a monopolistic public transport firm

Markets for transport are often characterised by unequal demand in both directions: every morning during peak hours the trains are crowded while moving towards the direction of large cities, whereas they may be almost empty in the other direction. In this paper we discuss the implications of these imbalances for price setting of transport firms. From the viewpoint of economic theory, two regimes can be distinguished: one where – owing to price discrimination – the flows are equal, and one where unequal flows are the result. Special attention is paid to the case where the transport firm does not apply price discrimination, as is the case with most railway firms in Europe. We find that in the case of substantial joint costs, the introduction of price discrimination not only leads to an increase of profits, but also to positive effects on consumer surplus. This result differs from the standard result in the literature on industrial economics. The standard result purports that with linear demand functions price discrimination has a negative impact on the welfare of the average consumer and that this negative impact dominates the positive effect on profits of the producer.     

The stability of stochastic equilibrium in a two-link transportation network

Most research and applications of network equilibrium models are based on the assumption that traffic volumes on roadways are virtually certain to be at or near their equilibrium values if the equilibrium volumes exist and are unique. However, it has long been known that this assumption can be violated in deterministic models. This paper presents an investigation of the stability of stochastic equilibrium in a two-link network. The stability of deterministic equilibrium also is discussed briefly. Equilibrium is defined to be stable if it is unique and the link volumes converge over time to their equilibrium values regardless of the initial conditions. Three models of route choice decision-making over time are formulated, and the stability of equilibrium is investigated for each. It is shown that even when equilibrium is unique, link volumes may converge to their equilibrium values, oscillate about equilibrium perpetually, or converge to values that may be considerably different from the equilibrium ones, depending on the details of the route choice decision-making process. Moreover, even when convergence of link volumes to equilibrium is assured, the convergence may be too slow to justify the standard assumption that these volumes are usually at or near their equilibrium values. When link volumes converge to non-equilibrium values, the levels at which the volumes stabilize typically depend on the initial link volumes or perceptions of travel costs. Conditions sufficient to assure convergence to equilibrium in two of the three models of route choice decision-making are presented, and these conditions are interpreted in terms of the route choice decision-making process.