An intelligent form system.

This thesis presents an investigation of developing a user-centred formbase system. It is based on the previous developments in Office Information Systems. It is technically related to AI Planning Systems and Database Systems. An Office System is an open system inside which the data, as well as the operations upon the data can not be pre-defined exactly. In order to set up a stable and flexible information system in such environments, the task representation, activity representation and data representation must be dynamically related to each other. This research concerns how to use AI planning system concepts to develop a formbase system. There are three crucial aspects: (a) how to represent an activity of information processing, (b) how to represent and refer to the data in the forms, and (c) how to construct the problem solving process for the task of information processing. For reasons of flexibility and stability in the open environment, it is important that a proper link between data representation and activity representation is achieved. This research has generated an Intelligent Form System. The contributions are: (a) the development of a form pattern language and the formbase which can represent and refer to the forms, (b) the identification of the formbase activity schema which can represent the activity upon the forms, and (c) the development of a problem solving process for the information processing tasks of the forms. The research has also recognized that the information processing activities upon forms are very different from the activities which are automatically performed by the Humans. Key Words: Office Information Systems; AI Planning Systems; Activity Representation; Action Reasoning; Knowledge Representation; Office Form Systems

A Novel Flux Weakening Control Strategy for Permanent Magnet Actuator of Vacuum Circuit Breaker

Traditional vacuum circuit breaker (CB) equipped with a bistable permanent-magnet (PM) actuator suffers from the disadvantages of having long start-up time and large current peak, and these shortcomings are limiting its applications on synchronization operation and high-voltage switchgear. In this paper, a new drive circuit which can significantly weaken the flux of the holding force with the usage of an auxiliary capacitor is proposed. In the proposed circuit, a negative current is circulated in the respective coil when the PM actuator is ready to switch on or off. Cosimulation which integrates the PM actuator and the circuit is carried out with the Maxwell and Simplorer software. The prototype is tested on the platform in conjunction with a 10-kV PM vacuum CB (VCB) to showcase the success of the proposed flux-weakening control strategy.Department of Electrical Engineerin

Speed Range Extension of Dual-Stator PM Machine Using Multi-Mode Winding Switching Strategy

In this paper, a novel winding switching (WS) strategy is proposed for the speed range extension of a dual-stator permanent magnet machine (DS-PMM), which can achieve simple and effective dynamic mode conversion over an entire operating region. Two types of WS circuits with an inverter and two switch groups were first designed to enable the winding reconfiguration of the machine, which could operate in three modes. The WS principle was then elucidated by introducing simplified equivalent circuits. Besides, the torque–speed curves of the machine under different operating modes were analyzed, based on the mathematical model. A speed-based WS controller was, subsequently, designed to generate the WS control signal and realize the multi-mode operation according to real-time operating conditions. The feasibility of the proposed WS strategy for extending the speed range of the DS-PMM was, finally, verified by experiments

Characterization of Elastic and Plastic Behaviors in Steel Plate Based on Eddy Current Technique Using a Portable Impedance Analyzer

A portable impedance analyzer (PIA) was developed based on a TiePie-HS3 device to provide the comparable impedance measurement accuracy of the Agilent 4294a impedance analyzer in the frequency range of 0~250 kHz. Then the PIA was applied to monitor the tensile stress-induced variation of the eddy current sensor’s impedance in a medium-carbon steel sample. A model of equivalent magnetic field induced by the elastic stress and the number of pinning sites indicated that the inductance of the eddy current loop firstly increased with the increase in the tensile stress and then decreased at the yield point of the material. The experimental results testified that the variation of impedance amplitude, the variation of phase angle, and the shift of two featured frequencies demonstrated opposite variation trends before and after the yield point, as predicated by the model. A new parameter, which combined the impedance variation information of the selected two frequencies, was found to exhibit nearly monotonous dependency on the tensile stress in elastic and plastic stages. The new parameter together with the developed portable impedance analyzer provided the solution to identify the elastic and plastic behaviors in ferromagnetic materials in practical applications with an eddy current technique