Preview Estimation and Control for (Semi-) Active Suspensions

An active suspension with preview is tested for rounded pulses and a stochastic road surface, and is compared to a passive suspension. The spectacular performance improvement obtained for a step function as road surface is not achieved but the improvement is still significant. The frequency response of the active suspension is determined for comparison with some suspension systems found in literature

An observer to reconstruct the preview information is presented. No model of the road surface is needed. From simulations, it appears that the observer reconstructs both deterministic and stochastic road surfaces satisfactory. However, the influence of measurement noise is not reduced sufficiently.     

Port state control versus marine environmental pollution

This work analyses whether port state control (PSC) has been effective in reducing environmental pollution in the region it covers. The analysis covers the technical and political aspects of PSC's effectiveness. To match the complexity of marine environmental pollution and safety issues, several indicators are developed to assess performance under both aspects. Previous studies on quantitative and qualitative material, as well as fresh evidence, are utilized to obtain quantitative or qualitative evaluations, as the case may be. The separate insights are then combined to reach an integrated conclusion. PSC is found to be effective in fighting marine environmental pollution, but with peripheral shortcomings of a mainly operational nature. These shortcomings limit the effectiveness to a less than optimal degree.     

FAST对10亿t总吨位的大轴重测试

美国联邦铁路管理局（FRA）的提速运营测度研究室（FAST），对重为143000kg,35.4t的大轴重车辆进行了测试，至今测试的总吨位已累计超过了10亿t，试验分5个不同的测试阶段，计划为开行大轴重车辆的安全性和经济性提供信息。     

Optimal Linear Active Suspensions with Derivative Constraints and Output Feedback Control

In optimally controlled active suspensions with either full or incomplete state feedback there is tradeoff between system performance and overall stiffness. It is sought to remove this limitation by incorporating integral action which results in a system with infinite stiffness towards static loading, but which is soft with respect to road inputs. The system is also able to eliminate the steady state deflections due to step and (potentially) ramp type inputs at the wheel. Optimality is retained at the cost only of a derivative constraint and the system can be physically realised using output feedback control.     

Performance indicator analysis: A management tool for the improvement of bus transit operation in Bangkok

This paper intends to demonstrate that the performance indicator analysis technique can be successfully used as a diagnostic tool to identify operational inefficiency and ineffectiveness at the route level of transit operation. The technique has been applied on 14 bus routes of Bangkok Mass Transit Authority to reveal the inter-route differences in operational efficiency and effectiveness. Twenty performance indicators relating to costs of services, fuel consumption, staff ratio, crew productivity, fleet utilization, service output per bus, daily revenues, etc., were selected to represent the resource efficiency, resource effectiveness and service effectiveness of the bus system. Results of the analyses revealed that considerable variations existed across the routes against many of these 20 selected indicators. These included variations in terms of labor and capacity utilization, maintenance expenditure, etc., many of which can be improved through suitable managerial measures. Based on these findings, specific recommendations have been made for improvement in the deficient areas that are considered to be within the operator domain. These indicators also provide a basis for comparison over time, with other operators and standards. A ranking scale was also developed to determine the over all attractiveness of the routes.     

Fracture toughness of steel plate from MV Kowloon Bridge

Chemical analysis, tensile, Charpy, DW NDT and fracture mechanics toughness data are presented for a grade A steel plate from the Kowloon Bridge, a sister ship of Derbyshire. The plate is shown to have poor toughness under dynamic loading conditions. The results leave open the possibility that brittle fracture could have contributed to a structural failure in the Derbyshire even at the high temperature of +30°C which is reported to have existed at the time of the ship's disappearance. The results are felt to support the proposition that present classification society rules need tightening to reduce the risk of brittle fracture in ships.     

Comparative advantage and maritime transport in the Baltic States

Conventional wisdom has it that, because of locational and other advantages, transit trade and transport, especially maritime transport, could be expected to play a major role in the development process of the Baltic States which was expected to follow their renewed independence in 1991. This paper secks to evaluate this proposition. The first section of the paper provides a brief account of the present state of the shipping and port sectors in the three Baltic republics and offers some speculation about likely future developments. The following section considers whether there is any historical basis for the presumption in favour of transit trade. The paper concludes with a somewhat speculative discussion of whether the Baltic States might be expected to possess any long run comparative advantage in maritime transport. It is suggested that in this respect a distinction should be made between ports and shipping and that in a more prosperous future, shipping, in particular, might be expected to decline in importance.