Allocation control algorithms design and comparison based on distributed drive electric vehicles

For a distributed drive electric vehicle (DDEV) which is equipped with redundant actuators, allocation control is a key technique. Three different allocation control algorithms are designated with fixed efficiency matrix, dynamic efficiency matrix, and direct yaw moment distribution, respectively. All these algorithms are applied in a vehicle stability control system with hierarchical control structure and evaluated from three aspects, namely, control precision, real-time characteristics, and control energy. Comparison results demonstrate that the algorithm with dynamic efficiency matrix has the best comprehensive performance, which is also validated in field tests based on a DDEV equipped with four motors.     

A model of traffic dispersion from a congested road

The study of traffic flow dynamics is developed by defining and clarifying traffic divergence, continuity, congestion and dispersion. Velocity potential is introduced as a gravity function generated by the interaction of two or more motorists occupying neighbouring points in space and describes interference to continuous traffic flow. The relationship between the potential function and carrying capacity is developed and dispersion, when considered as a random walk, satisfies a diffusion equation. A model of traffic dispersion along a maximum congested road in space and time is presented as eigenfunctions of the velocity potential. This suggests that traffic can be dispersed by a series of quantum steps. A probability density function is introduced to define the probability of locating a motorist in a congestion zone.     

Monitoring long-term environmental change: Some lessons from Sullom Voe,Shetland Islands

The impact on the marine environment of the operation of the Sullom Voe Oil Terminal and its major port facility in the Shetland Islands has been monitored continuously for more than twenty-five years. The site of this very large terminal straddles a peninsula and the separation of the impact of the port on the sheltered west side (Sullom Voe) and the aqueous discharge from the terminal to the east, into the strong tidal current of Yell Sound, has proven to be advantageous. There are two types of monitoring, statutory (to comply with relevant legislation) and voluntary (to establish good practice and to examine a wider range of impacts e.g. island-wide ornithology). The latter function is undertaken by an independent advisory committee (SOTEAG). Over time, the nature and amount of voluntary monitoring has decreased in response to the long term evidence that both terminal and port operations are having little or no impact on a wide range of habitats and species. Voluntary monitoring also acts as an independent check on both compliance and other forms of environmental assessment. Although the terminal is now operating at less than half its peak capacity, this does not mean that there has been apro-rata decrease in monitoring activity.     

Flow resistance characteristics of water in narrow annulus during heat exchange

Considering the special resistance characteristics of fluids flowing through ducts with small gaps, experiments are per-formed to investigate the resistance characteristics of single-phase water, which is forced to flow through vertical annuli. The gap sizes are 0.9, 1,4 and 2.4ram, respectively. The experiments are conducted under condition of 1 atm. The water in the annuli is heated by high temperature water reversely flowing through the inner tube and the outer annulus. The results show that the flow pattern begin to change from laminar to turbulent before Reynolds number approaches 2000, the flow resistance in annulus has llttie relations with the temperature difference and ways of being heated, but mainly depends on the ratio of mass flux to the width of annulus.     

Multimodal transport in the new millennium

Consignors of goods in international trade want their containers to move door to door whether by land, sea or air — smoothly, seamlessly and at predictable cost. What they actually get from the law is at best a jerky roller coaster: a series of contracts, one for each mode or stage of the journey, contracts with various people and with liability that varies too. All agree that the law should change but attempts to agree on an entirely new multimodal regime have failed. Recently attempts have been not to start again but to expand an existing and established regime. The latest of these, the UNCITRAL draft, is essentially maritime: it applies to the sea phase but and goes further to apply door to door except when its path is blocked by compulsory unimodal law. Has Venus at last arisen from the waves? And what will happen when Beauty meets the Beast in the form of CMR? This article addresses the problems that will be encountered by an ambitious amphibious instrument of this kind. — problems of integration, of compatibility with local legal culture, and of methodology.     

LD-pumped Ho, Tm： YLF microchip laser

A simple rate equation model for 2μm Tm, Ho:YLF laser is given to study laser dynamics. Under low pump power, the explicit formulae for the threshold pump power and the relation between output power and incident power are obtained. The present model provides a straightforward procedure to design the laser resonator and the optical coupling system for optimization. At the same time, the experimental results are reported. At room temperature the slope efficiency is 22.4% and the typical lasing threshold is about 328mW. The theory is in good agreement with experiment.     

New technology and maritime training in the 21<Superscript>st</Superscript> century: Implications and solutions for MET institutions

This paper examines the impact of new technology on MET institutions in the 21^st century and discusses to what extent global MET institutions can enhance and enrich traditional practices through access to new technology and the use of innovative teaching and assessment methods within a sustainable and achievable framework. It notes the diverse standards and access to new technology by MET institutions across the globe and discusses the implications for them if they are to remain competitive and viable. The paper concludes that maritime institutions can benefit from the use of new technology, but only through rational planning and sustainable staged growth. A series of continua of technical development is provided to assist institutions, from the smallest to the largest, to plan for technical development and growth in a rational and feasible way.     

Dynamic analysis of multibodies system with a floating base for rolling of ro-ro ship caused by wave and slip of heavy load

Common effect of wave and slip of internal heavy load will make rolling of the roll-on ship serious. This is one of the important reasons for overturn of ro-ro ships. The multibodies System with a floating base is composed of ro-ro ship and slipping heavy load. This paper takes the rolling angle of the ship and the transverse displacement of the heavy load on desk as two freedoms. Making use of analysis of apparent gravitation and apparent buoyaney, the wave rolling moment is derived. By use of dynamic method of multibodies system with a floating base, dynamic equations of the system are established. Taking a certain channel ferry as an example, a set of numerical calculation have been carried out for rolling response of the ship and displacement response of the slipping heavy load under common effect of synchro-slipping heavy loads and wave.     

Simulation study of plane motion of air cushion vehicle

This research is on horizontal plane motion equations of Air Cushion Vehicle (ACV) and its simulation. To investigate this, a lot of simulation study including ACV‘s voyage and turning performance has been done. It was found that the voyage simulation results were accorded with ACV own characteristic and turning simulation results were accorded with USA ACV‘s movement characteristic basically.