On the Performance Capabilities of Active Automobile Suspension Systems of Limited Bandwidth

Using methods established in earlier work, calculations are carried out to reveal the influence of actuator bandwidth on the performance capabilities of a class of active suspension system for automobiles. The suspension consists of an actuator in series with a spring, the combination being in parallel with a passive damper, and the system is modelled as a single wheel station traversing a random road. The results indicate that a system with a 3 Hz bandwidth actuator and variable damping will have excellent ride performance qualities over a wide range of road roughness conditions. Since such a system can be expected to be easily adaptable to the running conditions, to provide good static and dynamic attitude control, to be capable of contributing to good steering control responses and to be inexpensive in terms of capital and energy consumption costs compared with most of the active systems which have previously been discussed, it is suggested that it is a prime candidate for further study and practical development.     

Passive Safety Belt Operated by the Motor-car Door

The idea of a passive safety belt operated solely by the motor car's door has been rigorously analysed on a mathematical model. By calculation methods, an optimal configuration of the device was produced and a working model built, based on the analytically obtained design specifications. The model proved the feasibility and advantages of the proposed system, which is based on the conventional 3-point safety-belt design and utilises existing car structures.     

Canadian transportation regulation: Trends and issues

Transportation - In Canada, transportation regulation has evolved in response to the country's unique economic and demographic conditions—a land mass larger than that of the U.S.A. with...     

International relations and maritime dependence

This paper examines the growth of world trade in the period 1960-70 and its characterization by two indices, the Maritime Potential Index and the Maritime Dependence Index.     

Cargo handling productivity. Part 2. The findings

This is the second of two papers on cargo handling productivity presenting the results of the model developed int he first [1] which had been designed to test a productivity measurement method with cross-sectional empirical data. Four productivity measures were employed. Two related cargo handling to time, with labour brought into the analysis as an independent variable. The third productivity measure expressed total throughput as an aspect of labour productivity, while the final measure was a full productivity index developed by relating output to both capital and labour.

The productivity measurement technique demonstrated that this method can be used for cross-sectional studies and can cope with and allow for variation in non-controllable extraneous factors, thus proving useful for policy decision-makers in shipping lines and/or port authorities.

This paper presents the results of the prodictivity analysis for which the analytical design was decribed in Part 1. The first section briefly restates the productivity indices developed. The principal results and tests on these measures are present in Section 2 with conclusion following in Section 3.     

Experimental investigation of abrasive flow machining effects on injector nozzle geometries,engine performance,and emissions in a di diesel engine

The effects of the Abrasive Flow Machining (AFM) process on a direct injection (DI) Diesel engine fuel injector nozzle are studied. Geometry characterization techniques were developed to measure the microscopic variations inside the nozzle before and after the process. This paper also provides empirically-based correlations of the nozzle geometry changes due to the AFM process. The resulting impact of the process on the engine performance and emissions are also assessed with a DI Diesel engine test setup. This study shows that properly AFM-processed injectors can enhance engine performance and improve emissions due to the improved quality of the nozzle characteristics. However, an extended process can also cause enlargement of the nozzle hole as a side effect, which can adversely affect emissions. Emission measurements show the trade-off for the minimum levels as the process proceeds. Since the enlargement of the hole during the AFM process is not avoidable and must be minimized, strict control over the process is required. This control can be enforced by either limiting the AFM processing period, or by properly preparing the initial hole diameter so as to accommodate the inevitable changes in the nozzle geometry.     

Dynamic responses of a high-speed railway car due to wheel polygonalisation

The polygonal wear around the wheel circumference could pose highly adverse influences on the wheel/rail interactions and thereby the performance of the vehicle system. In this study, the effects of wheel polygonalisation on the dynamic responses of a high-speed rail vehicle are investigated through development and simulations of a comprehensive coupled vehicle/track dynamic model. The model integrates flexible slab track, wheelsets and axle boxes subsystem models so as to account for elastic deformations caused by impact loads induced by the wheel polygonalisation. A field-test programme was undertaken to acquire the polygonal wear profile and axle box acceleration response of a high-speed train, and the data are used to demonstrate the validity of the coupled vehicle/track system model. Subsequently, the effects of wheel polygonalisation are evaluated in terms of wheel/rail impact forces, axle box vertical acceleration and dynamic stress developed in the axle considering different amplitudes and harmonic orders of the polygonal wear. The results suggest that the high-order wheel polygonalisation can give rise to high-frequency impact loads at the wheel/rail interface, and excite some of the vibration modes of the wheelset and the axle box leading to high-magnitude axle box acceleration and dynamic stress in the wheelset axle.