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.     

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.     

An ERP approach for container terminal operating systems

The major characteristics of ERP (Enterprise Resource Planning) are an enterprise-wide system that covers all the business functions and information resources, integrated database, built-in best industry practice, packaged software and open architecture. ERP enables reduction of system development time, flexibility, standardization of workflow and effective business planning capability. ERP is mainly for the manufacturing industry. However, the principles of ERP can also be applied to container terminal operating systems. This paper presents an ERP system approach for a container terminal. It has clustered the workflow of a container terminal and analysed the business process to generate the best workflows. The integrated database is designed to eliminate redundancy and keep integration. The core of ERP for container terminal is the planning facility such as berth planning and yard planning. The planning capability is very tightly coupled with data flow from client entities such as shipping companies. The ERP can handle the existing problems of container terminal operation that are mainly caused by lack of integration of a whole information resource in a container terminal, ad-hoc and poor planning capability, disconnected and incorrect data from client companies. The ERP approach can not only resolve the problems of container terminals but also promote adoption of information systems for container terminals in the world that have not yet implemented terminal operating systems.     

Development of pictograms for dynamic traffic control systems in South Korea

This study developed a set of pictograms for lane control systems, to provide additional information to drivers on weather and traffic incidents. The results suggest that in the design of traffic signs, it is important to consider local context and not simply adopt standards and practices that are developed elsewhere. The differences in the social and cultural environments may affect the ease of reading and comprehension by local drivers. However, the study also showed that not all locally developed signs were rated higher for their ease of reading than others… Since some design characteristics are more salient, whereas others tend to be more dependent on the local context, it is important to conduct simple experiments and exploratory research to find the optimal designs to be used.     

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.     

Numerical determination of flushing time for stratified water bodies

It is often advantageous to model a semi-enclosed estuarine or coastal embayment (e.g. fish farms or tidal inlets, or typhoon shelters) as a separate system within a larger water body connected to the outer sea. The water quality of the system depends crucially on its flushing time—the average time of a particle in the system. The flushing time is governed by the barotropic and baroclinic tidal exchanges between the system and the outer sea. We describe herein a general method to determine systematically the flushing time of a stratified water body via a numerical tracer experiment. Numerical solution of the 3D flow and mass transport equations for many practical problems show that the tracer mass removal process depends on the physical topography and bathymetry, tidal range and the degree of stratification in the outer sea. Field application suggests that the tracer mass variation can be well approximated by a double-exponential decay curve that can be described by three flushing coefficients. Using a simple analytical two-segment model, the flushing coefficients can be given a clear physical interpretation, and the flushing time can be easily determined in terms of the coefficients. The method is illustrated by application to a number of tidal inlets in Hong Kong, in both the dry and wet season. The connection between the numerically determined flushing time and the traditional bulk flushing time obtained from salt-balance methods is established.     

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.