DOI:10.1049/ree.1984.0032

出版商:IERE    

年代:1984

数据来源: IET

摘要:

Anti-sound techniques enable acoustic and vibrational fields to be mimicked and cancelled bysecondary sources. That is, an unwanted sound can be suppressed if it can be completely reproducedin amplitude and phase over a required frequency range and over an area of required extent bysecondary sources. Devices for exploiting this aspect of linear wave fields has been experimented withfor over 50 years but it is only in the last decade that active noise control have emerged as a practicalpossibility as a result of the rapid development of electronic sensing processing techniques.

DOI:10.1049/ree.1984.0033

出版商:IERE    

年代:1984

数据来源: IET

摘要:

A feasibility study into the use of broadcast telesoftware in secondary education was conducted jointly with the BBC and IBA using prototype equipment developed by Mullard. Using the BBC Microcomputer and its teletext adapter the study is being extended to primary education and 40 schools are taking part in extensive trials

DOI:10.1049/ree.1984.0036

出版商:IERE    

年代:1984

数据来源: IET

摘要:

Mercury, the licensed competitor to British Telecom is creating a digital telecommunication network in the United Kingdom based on ‘state of the art’ techniques. Operations have commenced with a leased line service and switching will be introduced in 1985 whilst an international service will commence via satellite during 1984. The wideband capability of digital transmission will enable many new services to be introduced

DOI:10.1049/ree.1984.0037

出版商:IERE    

年代:1984

数据来源: IET

摘要:

The historical development of techniques for prediction of transient response sensitivity of SISO feedback control systems to plant changes is reviewed starting with the analogue approach of Tomovic and leading up to the current state of the art. It is shown that for a given transient response performance specification, significant and quantifiable improvement in sensitivity reduction can be achieved in conventional systems by including feedback compensation.Extension of the methodology to the prediction of the transient response sensitivity of high-order systems via loworder models is included. The problem of parameter tolerance setting to meet a performance envelope specification is used to illustrate the method. Finally, transient response sensitivity functions are used to assess the relative merits of systems stabilized by sensor measurements compared to observer compensation. The intuitive assumption that the observerbased design (which is readily implemented via microprocessor technology) is less robust than an instrumented system is confirmed

DOI:10.1049/ree.1984.0038

出版商:IERE    

年代:1984

数据来源: IET

摘要:

This paper describes an impulse-response method to find the low-frequencyy-parameters of d.c. to d.c. switching converters in both the continuous and discontinuous modes. Using an example of a forward converter, the applications of they-parameters are illustrated by the determination of: the general equivalent circuit; the d.c. output voltage; the critical condition between continuous and discontinuous modes of operation; the equivalent circuit under steady state condition; the transfer function between small change in d.c. input voltage and the resultant change in d.c.output voltage; the transfer function between small change in duty cycle and the resultant change in d.c. output voltage. They-parameter approach can easily be applied to other types of converter circuits. Its simplicity makes it particularly suitable for more complex types of converters

DOI:10.1049/ree.1984.0039

出版商:IERE    

年代:1984

数据来源: IET

摘要:

Videotex is an electronic information service which allows the sighted user to access a vast amount of information via the telephone line, to be viewed on the screen of the domestic television receiver in a compact and colourful layout. In this paper, the development of a microprocessor based system for converting videotex pages to synthetic speech in real time, for the benefit of blind people, is described. The system has been successfully used by some blind people to access the British Telecom videotex service (Prestel).

DOI:10.1049/ree.1984.0040

出版商:IERE    

年代:1984

数据来源: IET

摘要:

The system developed can interface a central mini-computer to an established medium-size machine shop including a range of NC and CNC machine tools. The system distributes NC part program data as well as job planning and tooling data, eliminating many of the disadvantages associated with the use of paper tape, and enhancing machine tool utilization and thus return on capital investment. The system incorporates real-time machine-shop monitoring with an integrated communications and information network, which can encompass a multiplicity of departments within an organization, and as such is best described as a Factory Information System (FIS). The benefits include increased management control and the basis for a further development to a full flexible manufacturing system (FMS). The design of interface units and the structure of the software required to drive such a system are proposed.

DOI:10.1049/ree.1984.0041

出版商:IERE    

年代:1984

数据来源: IET