Gulf of Gdansk spring bloom physical, bio-optical, biological modelling and contact data assimilation

In this study we propose a model of phytoplankton population dynamics in the marine ecosystem, which includes physical, biological and bio-optical parts. As an example we simulate the abnormal 1993 Gulf of Gdansk spring bloom, when extremely high chlorophyll concentrations were observed. For the one-dimensional model we use two different methods of contact chlorophyll observation assimilation to fit a model of “in situ” data. The results are compared with two-dimensional ecosystem modelling based on a barotropic model of wind-driven circulation without assimilation.     

Fuzzy and adaptive fuzzy control for the automobiles' active suspension system

Two typical criteria for good vehicle suspension performance are their ability to provide good road handling and increased passenger comfort. The main disturbance affecting these two criteria is terrain irregularities. Active suspension control systems reduce these undesirable effects by isolating car body motion from vibrations at the wheels. This paper describes fuzzy and adaptive fuzzy control (AFC) schemes for the automobile active suspension system (ASS). The design objective is to provide smooth vertical motion so as to achieve the road holding and riding comfort over a wide range of road profiles. The efficacy of the proposed control schemes is demonstrated via simulations. With respect to the optimal linear quadratic regulator (LQR), it is shown that superior results have been achieved by the AFC.     

Hatchcoverless container ships: productivity gains from a new technology

The hatchcoveless container ship is an innovative design which improves cargo handling productivity. The paper develops a methodology for measuring the gains. To illustrate the impact of faster port times on voyage profitability a voyage cost analysis is used to show its operational advantages. An investment analysis demonstrates the value which will accrue to the company over the life of the vessel.     

A study of the changes in performance of quayside container cranes

The learning effect, whereby performance improves with experience, is well documented for manufacturing situations. This article applies these learning concepts to quayside container cranes, in order to determine the relationship between number of containers moved and unloading time. The results show that crane performance has improved with time, and that the learning effect is essentially the same for four ports. Container vessel operators are looking for consistency in port operations. An analysis of variability for one port shows that this consistency is not always achieved and that crane performance does not appear to be related to vessel size.     

Energy savings due to land transportation management in Singapore

Singapore has been actively engaged in implementing various land transportation policies and traffic management schemes since the early 1970s to reduce traffic congestion. This paper examines the benefits in energy savings arising from the following five major schemes: (a) the Area Licensing Scheme, (b) the computerised Area Traffic control System, (c) the adaptive traffic control system, (d) the exclusive bus lane scheme, and (e) the island-wide expressway system. The analyses are made based on the findings of a two-year study that developed vehicle fuel consumption models for Singapore traffic. The Area Licensing Scheme that restricts traffic flow into the Central Business District (CBD) is found to have the greatest energy impact, followed by the island-wide expressway system and the traffic-signals control systems within the CBD.     

Gateway diversity and competition in international air transportation

Because of the existence of limited designation gateways, i.e., gateways for international air travel where entry by U.S. flag carriers is limited (in many cases to only one carrier), the U.S. Civil Aeronautics Board (CAB) has announced a policy of gateway competition. This policy seeks to maximize inter-gateway competition as a goal of the carrier selection process. The paper reviews the rationale and history of this policy and the economic principles of gateway competition. After addressing exceptions where gateway competition does not enhance competitive goals, the issue of how to enforce the credibility of the bidding process in route awards is addressed. The paper concludes by identifying circumstances where competitive objectives are not advanced through application of the principle gateway competition.     

Evaluating employer programs encouraging the use of alternate transportation modes: Two studies

Since 1976, major Denver metropolitan area firms have been required to encourage employees to use mass transit, carpooling, bicycling, and other alternate transportation modes to commute to work. The encouragement programs of 36 firms were clearly associated with greater use of alternate transportation modes, with the portion of variance in alternate transportation use explained by differences in employer programs of approximately 15%. The effects of the programs on deterring alternate mode users from returning to solo driving are consistently weaker than their effects on persuading drivers to try alternate transportation modes initially. Recommendations for the conduct of alternate transportation encouragement programs are made, based on these and other results. In addition, two recommendations are made concerning the evaluation of encouragement programs: that aggregate percentage change in alternate transportation use should not be used as the sole measure of success, and that environmental variables such as the availability of and pressure for use of alternate transportation modes should be measured and controlled.