Introduction to an innovative crew composition approach based on safety/operational and financial requirements

This paper proposes a tool to estimate crew composition based on safety/operational and financial requirements. As there is a tendency of ship owners to implement improved technologies on board their vessels, there is no systematic way to predict their potential effect on crew size and composition (typically determined by flag state authorities on a case-to-case basis) nor on the type and complexity of on board duties new technologies might dictate. The main aim of this paper is to develop a tool to assist in determining crew composition, by taking into account both administration’s and the ship owner’s point of view. Based on data collected from ship owners, a data mining technique is implemented in order to form a generalized framework that estimates crew composition as a function of ship type, size, and degree of automation. The agreement of model predictions with records from specific (vessel) cases is very good in terms of safety (for operations such as watchkeeping, mooring/unmooring, loading/unloading). The specific intended use of this tool is to help a ship owner decide whether it is cost-beneficial to retrofit a conventional vessel with advanced technologies that would potentially entail a reduced crew (probably dealing with different and more complex on board duties). Its main benefits are that it can be used to estimate crew composition before any vessel construction or upgrade has actually taken place and that it allows crew composition to be easily adapted to the technological evolution of ship systems even at their current rapid pace.     

Plankton distribution and the impact of copepod grazing on primary production in Fram Strait, Greenland Sea

Two hydrobiological transects across the East Greenland Shelf and the open waters of Fram Strait in summer were chosen to illustrate the distribution and production of phyto- and zooplankton in relation to water masses and ice cover. The parameters used were temperature and salinity, inorganic nutrients, chlorophyll a, primary production, phytoplankton species composition, abundance of the dominant herbivorous copepods Calanus finmarchicus, C. glacialis, C. hyperboreus, Metridia longa and egg production of C. finmarchicus and C. glacialis. Grazing impact of copepodites and adults of these four species was modelled for each station by using egg production rates as an index of growth. Seasonal development of plankton communities was closely associated with the extent of the ice cover, hydrographic conditions and the water masses typical of the different hydrographic domains. Four regions were identified from their biological activities and physical environment: The Northeast Water polynya on the East Greenland Shelf, with a springbloom of diatoms and active reproduction of herbivorous copepods. The pack ice region, dominated by small flagellates and negligible grazing activities. The marginal ice zone, with high variability and strong gradients of autotroph production related to eddies and ice tongues, an active microbial loop and low egg production. The open water, with high station-to-station variability of most of the parameters, probably related to hydrographic mesoscale activities. Here, Phaeocystis pouchetii was a prominent species in the phytoplankton communities. Its presence may at least partly be responsible for the generally low egg production in the open waters. Grazing impact on primary production was always small, due to low zooplankton biomass in the polynya and due to low ingestion in the remaining regions.     

The future of transit technology: Lessons from EXPO 86

Expo 86, the World Exposition held last year in Vancouver, Canada, was the largest, special-category world's fair ever staged, with 54 international participants. Given the designated theme of transportation and communications, it is interesting to interpret the statements made by the participants in regard to particular sub-theme areas such as urban transit. This paper reviews the presentations (exhibits, demonstrations, conferences, and seminars) developed by all participants in Expo 86 in regard to urban transit technology, and assesses the significance and direction of technological developments in the areas of vehicle and terminal design, network and system operation and control, and planning and management systems.     

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.     

Defining domains for models of travel demand

Travel demand models implicitly assume that people respond to changes in a continuous way. This is in contrast to the physical sciences, where discontinuous response is a common phenomenon and is embodied in such concepts as sub-critical and supercritical states.Recent studies have shown that responses to transport policies differ in degree and kind according to the nature and severity of the stimulus and the types of people affected. Response patterns may be categorised by the extent to which they involve adjustments to spatio-temporal or inter-personal linkages. This paper identifies four response domains, with a further distinction between permissive and forced changes.Most travel demand models are designed to operate within an independent, forced (and to a less extent independent permissive) domain and their forecasts become unreliable when responses lie outside that domain. Conversely, a model designed for a more complex domain is unnecessarily cumbersome where simpler responses apply. This paper describes the types of model which are appropriate for each domain and discusses how the effects of a policy may be assigned to the correct domain(s).     

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.     

Mass transit in developing cities

Using case study material, this paper examines the relative merit of metros and high performance bus systems in use in Third World cities. It demonstrates that buses with suitable priority measures are capable of meeting high passenger demands. The paper also shows that despite the poor financial performance and other shortcomings of metros, they can yield a respectable economic return. The paper draws on studies undertaken as part of the research program of the Overseas Unit of the Transport Research Laboratory.     

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.