Validation of a schedule‐based capacity restraint transit assignment model for a large‐scale network

This paper describes the application of a capacity restraint trip assignment algorithm to a real, large‐scale transit network and the validation of the results. Unlike the conventional frequency‐based approach, the network formulation of the proposed model is dynamic and schedule‐based. Transit vehicles are assumed to operate to a set of pre‐determined schedules. Passengers are assumed to select paths based on a generalized cost function including in‐vehicle and out‐of‐vehicle time and line change penalty. The time‐varying passenger demand is loaded onto the network by a time increment simulation method, which ensures that the capacity restraint of each vehicle during passenger boarding is strictly observed. The optimal‐path and path‐loading algorithms are applied iteratively by the method of successive averages until the network converges to the predictive dynamic user equilibrium. The Hong Kong Mass Transit Railway network is used to validate the model results. The potential applications of the model are also discussed.     

The place of the ISPS Code in the legal international regime

The adoption of the International Ship and Port Facility Security Code (ISPS Code) is the latest response of the international shipping community to the increasing threat posed by acts of terrorism at sea. The ACHILLE LAURO incident of 1985 showed that the traditional law against piracy was not adequate to deal with new types of unlawful acts against international shipping, especially those involving acts of terrorism. The 1988 Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation (SUA Convention) and the technical and administrative measures adopted by the Maritime Safety Committee of IMO in 1986 and 1996 attempted to develop a broader regime to deal with unlawful acts against international shipping.However, the events of September 11, 2001 showed that additional measures were still needed to prevent terrorist attacks against ships.     

From privilege to peril

This article addresses the growing concern over the diminishing legal rights and increasing responsibilities of those in command of ships today. A number of high-profile maritime accidents have focussed on the dilemma faced by shipmasters who appear to be held responsible for actions over which they have little or no control. This seems to indicate that the traditional privilege and honour associated with command appears to have become a risky burden. The article discusses the legal rights and responsibilities that shipmasters have today in terms of international maritime law and policy. Four case studies are utilized to illustrate the problem.     

Hydrographic cruises off northwest Africa: the Canary Current and the Cape Ghir region

We present hydrographic data for several sections located along the African coastline and off Cape Ghir, carried out at times of weak surface winds (October 1995 and September 1997). The main sections are near the continental slope, at mean distances between 100 and 150 km from the coastline. North of Cape Ghir (31°N) the geostrophic transport (referenced to 650 m) of North Atlantic Central Water through these sections is 3.7 and 2.0 Sv for 1995 and 1997, respectively. This confirms that a major fraction of the water transport by the Canary Current flows east, into the continental slope off northwest Africa, at latitudes above Cape Ghir. Most of this flow continues south past Cape Ghir, along the coast and probably through the eastern passages of the Canary Archipelago. A significant fraction, however, may escape through surface Ekman transport (0.3–0.5 Sv during the early fall season) and by offshore flow at Cape Ghir (1.1 Sv in September 1997, referenced to 650 m). Despite the weak winds the Cape Ghir filament was clearly visible, characterized by localized coastal upwelling associated to a cyclonic shallow structure and cold (and fresh) waters stretching offshore as a very shallow feature (50–100 m deep). The satellite images show that the surface temperature field is highly variable, in rapid response to the surface winds, always with a core region of relatively cold water and commonly with one or two associated eddies. Our results support the existence of two recirculation cells in the area: a horizontal one that connects the interior eastern boundary currents with the coastal region and a vertical one related to both wind-induced and filament upwelling. The data also show a salinity subsurface maximum at the root of the filament, linked to water inflow from northern latitudes, and a subsurface anticyclonic eddy over the Agadir canyon, likely related to the poleward slope undercurrent.     

Editorial prologue

Abstract

The economic and environmental consequences of a proposed Louisiana superport have been studied by researchers during the last three years. These studies provided technical information and management alternatives. Management alternatives included state control to avoid multiple superport developments, details for an Environmental Protection Plan, comparisons of onshore and offshore sites, and planning for ancillary development. Policy decisions which resulted include many of the recommendations of the research. It is suggested that environmental research can influence policy decisions and limit the options available to a decision maker provided some legal structure is created, quality control is implemented, and technological and environmental problems are recognized. Various analytical tools, such as energy cost accounting, group critique, and simulation models, have wide application for use in coastal zone management.     

Cooperative tourism and the coastal zone

Abstract

Most tourist development takes place in the coastal zone. Concentrated tourist use continues in spite of opposition by groups who feel that any tourism, especially international, threatens both the natural environment and local values. Although shorelines and “coastscapes”; belong to all, decisions regarding them are made by relatively few. The number of community organizations involved in coastal zone management decisions varies from almost none in some Third World countries to dozens in places like Hawaii or California. Constructive use of coastal zones requires an understanding of the interactions between biophysical and social systems. Planning tourism in this context requires that all groups with an interest in the coastal zone join in a new “cooperative tourism”; in which all contribute to decisions and face ultimate responsibilities.     

Fault Diagnosing System of Steam Generator for Nuclear Power Plant Based on Fuzzy Neural Networks

All kinds of reasons are analysed in theory and a fault repository combined with local expert experiences is establishedaccording to the structure and the operation characteristic of steam generator in this paper. At the same time, Kohonen algo-rithm is used for fault diagnoses system based on fuzzy neural networks. Fuzzy arithmetic is inducted into neural networks tosolve uncertain diagnosis induced by uncertain knowledge. According to its self-association in the course of default diagnosis. thesystem is provided with non-supervise, self-organizing, self-learning, and has strong cluster ability and fast cluster velocity.     

3-D computational method of wave loads on turret moored FPSO tankers

A three-dimensional method of calculating wave loads of turret moored FPSO (Floating Production Storage and Offloading) tankers is presented. The linearized restoring forces acting on the ship hull by the mooring system are calculated according to the catenary theory, which are expressed as the function of linear stiffness coefficients and the displacements of the upper ends of mooring chains. The hydrodynamic coefficients of the ship are calculated by the three-dimensional potential flow theory of the linear hydrodynamic problem for ships with a low forward speed. The equations of ship motions are established with the effect of the restoring forces from the mooring system included as linear stiffness coefficients. The equations of motions are solved in frequency domain, and the responses of wave-induced motions and loads on the ship can be obtained. A computer program based on this method has been developed, and some calculation examples are illustrated. Analysis results show that the method can give satisfying prediction of wave loads.     

A capacity restraint transit assignment with elastic line frequency

This paper proposes a new formulation for the capacity restraint transit assignment problem with elastic line frequency, in which the line frequency is related to the passenger flows on transit lines. A stochastic user equilibrium transit assignment model with congestion and elastic line frequency is proposed and the equivalent mathematical programming problem is also formulated. Since the passenger waiting time and the line capacity are dependent on the line frequency, a fixed point problem with respect to the line frequency is devised accordingly. The existence of the fixed point problem has been proved. A solution algorithm for the proposed model is presented. Finally, a numerical example is used to illustrate the application of the proposed model and solution algorithm.     

与速度有关的高负荷轮轨接触的粘着力(一)

为确定与速度有关的轮轨间的粘着力,设计了一种包含了与温度、弹性模数以及屈服点有关的动力学模型.