The MEPLAN models of Bilbao,Leeds and Dortmund

A trio of closely related land‐use/transport interaction models was developed using Marcial Echenique & Partners’ software package MEPLAN. The models were for the cities of Bilbao, (Spain), Dortmund (West Germany) and Leeds (England). All were calibrated using data drawn from earlier studies. The three models were used to predict the effects (relative to a base case) of a common programme of land‐use and transport policies or scenarios. This paper explains briefly the theoretical basis of the MEPLAN package as applied to urban models such as these three; describes the types of policies that have been assessed; and presents some of the key results.     

A segregated urban busway system

A transport system has been proposed using buses operating over ordinary roads and over special reserved tracks (busways) on which they might be automatically guided. Using cost and performance data resulting from an earlier technical study (not reported here), a hypothetical network of routes and services in the West Midlands conurbation is studied. Estimates of patronage diverted from public and private transport enable the profitability of the system and its costs and benefits to be assessed. It is concluded that the system could be attractive both in commercial and in cost/benefit terms, providing acceptable means could be found for handling the buses around and through the inner central areas of cities. The net environmental changes, which would result from additional fixed plant permitting more efficient use of mobile plant, have not been quantified.     

Accessibility in the regional CGE framework: the effects of major transport infrastructure investments in Poland

Transportation - Since its EU accession, Poland has invested strongly in the development of fast road transport network. As a result, the total length of modern, high-speed roads has increased from...     

Fuzzy logic based decision making system for collision avoidance of ocean navigation under critical collision conditions

This paper focuses on a fuzzy logic based intelligent decision making system that aims to improve the safety of marine vessels by avoiding collision situations. It can be implemented in a decision support system of an oceangoing vessel or included in the process of autonomous ocean navigation. Although Autonomous Guidance and Navigation (AGN) is meant to be an important part of future ocean navigation due to the associated cost reduction and improved maritime safety, intelligent decision making capabilities should be an integrated part of the future AGN system in order to improve autonomous ocean navigational facilities. In this study, the collision avoidance of the Target vessel with respect to the vessel domain of the Own vessel has been analyzed and input, and output fuzzy membership functions have been derived. The if–then rule based decision making process and the integrated novel fuzzy inference system are formulated and implemented on the MATLAB software platform. Simulation results are presented regarding several critical collision conditions where the Target vessel fails to take appropriate actions, as the “Give way” vessel to avoid collision situations. In these situations, the Own vessel is able to take critical actions to avoid collisions, even when being the “Stand on” vessel. Furthermore, all decision rules are formulated in accordance with the International Maritime Organization Convention on the International Regulations for Preventing Collisions at Sea (COLREGs), 1972, to avoid conflicts that might occur during ocean navigation.     

Dynamic motions of planing vessels in head seas

The dynamic response of planing vessels in regular head seas is investigated numerically. Nonlinear time domain simulations were performed using a 2D + t theory (two-dimensional plus time dependent theory). A prismatic hull form was assumed. We employed a two-dimensional (2D) boundary element method to solve the initial boundary value problems in 2D cross planes, in which nonlinear free-surface conditions and exact body boundary conditions were satisfied. At each time step, the total force and moment on the hull could be obtained by using the sectional forces calculated in those 2D planes. Heave and pitch motions were then acquired by solving the equations for those motions. The calculated heave and pitch responses were compared with the experiments by Fridsma (A systematic study of the rough-water performance of planing boats. Davidson Laboratory Report R-1275, 1969) for two different Froude numbers. Three-dimensional (3D) corrections at the transom stern were applied to show the influence of the 3D effect at the stern on the numerical results. Ship motions were affected by the 3D corrections, especially near the resonance frequency, while the phase angles were slightly affected and the acceleration peaks at the bow near the resonance frequency were sensitive to the 3D corrections. Other error sources in the theoretical results are also mentioned.     

Multi-fidelity optimization of a high-speed foil-assisted semi-planing catamaran for low wake

The wakes of high-speed passenger-only ferries that operated through Rich Passage, on the Seattle-Bremerton ferry route, caused beach erosion and damage to habitat. A task was initiated to design a low-wake high-speed vessel using multi-fidelity CFD based design optimization by using low-fidelity potential flow solvers for initial global design optimization and by using URANS solvers for high-fidelity tuning of the optimized design. This simulation based design process involved a close collaboration between ship designers, and hydrodynamics and CFD specialists, whose collective expertise guided the evolution of the design based on both hydrodynamic and structural aspects. The initial hull shape optimization using potential flow code was carried out by blending three different initial concepts provided by the designers. Subsequently, URANS was used to evaluate the potential flow optimized hull and to further optimize the hull configuration parameters, namely, the centre-of-gravity, demihull spacing, foil location, foil angle and slenderness ratio at different displacement conditions. The URANS based configuration optimization also took into account the far field wakes’ energy spectrum with an objective of reducing the energetic, low frequency far field wakes which are associated with beach flattening on the mixed sand and gravel beaches. Calculation of the far field wake using URANS would require an unfeasibly large domain size; therefore, a Havelock code with a source distribution matching the URANS calculated near field wave elevation was used to propagate the wakes into the far field. The end result of the optimization was a design with significantly reduced far field wake, which is currently being built for experimental testing.     

The effect of sloshing on the sway motions of 2D rectangular cylinders in regular waves

In this paper, we investigated the effect of sloshing on the sway motions of two-dimensional rectangular cylinders in regular waves, bearing in mind possible applications for LNG-FPSO and LNG-FSRU. First, we carried out experiments for two models with different drafts, or the same draft but different filling ratios, in which the models were firmly connected to each other. The sway motion was measured with a noncontact video camera. This is an extension of Rognebakke and Faltinsen’s work for a single model (J Ship Res 47(3):208–221, 2003). It was found that the sway motion became small when the incident wave frequency was close to the lowest natural frequency of each model. The sway motion greatly increased when the wave frequency was higher than this frequency. The measured data were compared with numerical results obtained by a single-dominant multi-modal method; relatively good agreement was noted. However, the numerical results deviated from the experimental results near the lowest natural frequency of the smaller model, which was believed to be due to overturning waves, as observed during the experiment. Since this is out of the valid range for the single-dominant multi-modal method, other, more appropriate, methods such as the multi-dominant modal method must be applied instead.