Hydro-pneumatic Slow-active Suspension with Preview Control

In this work, the preview control problem is considered for fully active and hydro-pneumatic slow-active systems. Based on the quarter car model, linear optimal control theory is used to derive the control laws. The Pade approximation technique is used to represent the preview time resulting from a preview sensor mounted at the front bumper to measure the road irregularities ahead of the front wheels. The results for the slow-active system with preview showed that there is 15% improvement in ride comfort compared to slow-active without preview and 28.5% improvement over passive system at similar root mean square (r.m.s) dynamic tyre load and suspension working space. The performance gains are, however, lower by about 15% than those obtainable with the theoretically ideal, fully active system with preview. The power results for slow active with and without preview showed that a 2kW fixed displacement hydraulic pump is enough for full vehicle requirements.     

Aspects of family and kinship in a North Carolina coastal community: a comparative study

The almost total absence of social-science data on North Carolina coastal fishing communities has provoked this preliminary study of the role played by family and kinship ties among fishermen and boat builders in such a community, with a view to developing new fisheries management strategies from an assessment of the social and economic impacts of those which already exist.     

Effects of waste disposal on benthic faunal succession on the abyssal seafloor

Strategies to predict, and thus limit, potentially detrimental environmental impacts of abyssal disposal of wastes are severely limited by our lack of knowledge of deep-sea processes and lack of opportunity to directly study waste disposal in abyssal environments. Probable successional sequences following burial of benthic faunas by sewage sludge and dredged material on the abyssal seafloor are drawn by analogy with well-known processes in shallow-marine water. Scales of change and recovery of abyssal benthic faunas from episodic deposition of waste material are examined by extrapolation from what is currently known about turbidite sedimentary provinces, in particular, the Venezuela Abyssal Plain and the Great Meteor East area of the Madeira Abyssal Plain. Results suggest that initial benthic faunal recolonization would take place within years following episodic depositions of waste on the abyssal seafloor. Anoxic conditions or chemical inhibitory effects may delay initial benthic recolonization for hundreds of years. Establishment of equilibrium benthic faunal assemblages probably takes hundreds to potentially thousands of years. Potentially detrimental effects dictate that the surface areas of individual waste deposits should be minimized and the deposits should be isolated by capping with nontoxic materials or chemical barriers.     

Track Induced Heave-Pitch Dynamics of Vehicles with Variable Section Flexible Attachments

Multi-wheeled vehicles travelling on a rough track are subjected to unequal inputs at different wheel locations and are set to oscillate in various combinations of possible modes. Elastic bending and torsional deformations may be critical in design for vehicles with slender flexible body and components. In the present study, an analytical approach has been developed to study the track induced heave-pitch dynamics of a linear vehicle model composed of lumped masses and slender, non uniform section elastic attachments in coupled bending-torsion modes. Exact modal solutions for the variable section beam member with general end conditions have been derived and utilised to develop the second order response statistics for the system. Results are presented for an aircraft model with tapered flexible wings during ground runs on a non homogeneously profiled track supported by elastic foundation.     

Ultimate torsional strength of flat-bar stiffeners attached to flat plating under axial compression

A parametric study based on numerical analysis using an efficient non-linear finite element method code is presented for the simulation of the interactive flexural-torsional failure behaviour of flat-bar stiffeners in plates under uniform axial compression. The restraining effect of the structural components on one another is investigated by varying the plate and stiffener slenderness. Initial imperfection levels partinent to marine structures have been accounted for. Strength curves for the allowable stress at the top of the stiffener due to elasto-plastic torsional buckling are given for use with approximate design formulas.     

The exclusive economic zone: criteria and machinery for the resolution of international conflicts between different users of the EEZ

It is highly probable that one of the results of the Third United Nations Conference on the Law of the Sea will be the recognition of a new jurisdictional zone—the exclusive economic zone (EEZ). This 200-mile zone will be used for a variety of potentially conflicting purposes by both the coastal state and non-coastal states and it is therefore important to ensure that the new convention emerging from the conference should establish criteria and make provision for machinery for the resolution of the international conflicts between different users which will undoubtedly arise. This paper contains a critical analysis of the latest draft articles under consideration at the Conference and considers the criteria by reference to which disputes might be resolved.     

On the measurement of benefits from shipping services

This brief paper extends the author's comments on Conference pricing policy, and represents a reply to comments made by E. T. Laing.