Difference Operator

Abstract. In this paper, a decision support tool that automates crew recovery during irregular operations for large-scale commercial airlines is presented. The tool is designed for airlines that adopt the hub-spoke network stru cture. The advance of this tool over the existing ones is ...

A comprehensive approach to the design and implementation of multi-robots cooperative systems is described. It focuses on a design process that uses the Unified Modeling Language and on a detailed ontology description with the goal of sharing the knowledge on environments that robots can acquire through the use of their vision sub-system. We base the implementation of our robotics vision system on agents inserted in a generic multi-level architectures. The first objective of this work is to provide a framework ...

The theoretic fundamentals of distributed information fusion are well developed. However, practical applications of these theoretical results to dynamic sensor networks have remained a challenge. There has been a great deal of work in developing distributed ...

This paper presents the design, analysis and implementation of a proposed combined three phase induction motor and its drive system to meet the demand of low-voltage electrical system for hybrid and electric cars, avoiding the high voltage human risks, expensive and complex requirements of the higher voltage insulation and power electronic devices. The development of electric vehicle technologies has been

The main objective of this work is to establish appropriated ways for estimating the efficiencies of valve trays with downcomer and dualflow trays of industrial distillation columns. The knowledge of efficiencies has fundamental importance in the design and performance evaluation of distillation columns. Searching in the literature, a tree of alternatives was identified to compose the tray efficiency model, depending

The development of power semiconductors, specially IGBTs has led to the small power HVDC transmission based on voltage source converters (VSCs). The VSC based HVDC transmission system mainly consists of two converter stations connected by a dc cable. This paper presents the modelling and control design of VSC based HVDC which uses twelve pulse three level converter topology. The reactive current injected by individual VSCs can be maintained constant or controlled to regulate converter bus voltage constant. While one VSC regulates the dc bus voltage the other controls the power flow in the dc link. Each VSC can have up to 4 controllers depending on the operating mode. The controller structure adopted for power controller is of PID type and all other controllers are of PI type. Each operating mode requires proper tuning of controller gains in order to achieve satisfactory system performance. This paper discusses a systematic approach for parameter optimization in selecting controller ...

Methods. A prospective postal survey (n = 785) was undertaken during a 12-month period in 1998/1999 involving three day surgery units in three different areas in England and Wales and based on three commonly performed operation types: hernia repair, varicose vein surgery ...