Measurement and Control

Chang, J. A.; Owen, A. G.; Zaman, M.; Griffin, A. W. J.

doi: 10.1177/002029406800100408pmid: N/A

Barker, H. A.; Murray-Smith, D. J.

doi: 10.1177/002029406800100406pmid: N/A

The transient response of a linear feedback control system is characterised by the s plane pole positions of the closed-loop system transfer function, particularly by those of the dominant poles. During a design procedure these pole positions are changed by varying the parameters which are under the control of the designer until the transient performance specification of the system is satisfied. These pole positions can also change as a result of variations in system parameters not under the control of the designer, for example, due to component tolerances or environmental changes. A necessary part of the design procedure is therefore the determination of the sensitivities of the pole positions to system parameter variations. Insofar as the design procedure seeks to predict closed-loop system behaviour from open-loop system information it is desirable that these sensitivities are determined from the same information in order that sensitivity considerations may be introduced at an early stage. This may be accomplished by an extension of the complex frequency response method for feedback control system design.

Hensley, G.

doi: 10.1177/002029406800100407pmid: N/A

Safeguards, for costly and hazardous chemical plants, are often provided by means of alarm or automatic shutdown systems. The adequacy of this protection—which is a measure of the capability of the newly installed system in shutting down the plant on the occurrence of a hazardous condition, and its effectiveness over the long term (its reliability)—may be judged by an independent safety assessment. Both qualitative and quantitative aspects of safety analysis are involved in an assessment, the quantitative approach being of particular use where there is a need to compare the anticipated reliability of the proposed system with a numerically specified, reliability requirement.Some of the techniques used in the assessment procedure are discussed in the paper and, by way of example, the performance of a typical shutdown system is assessed and its adequacy judged against a hypothetical plant fault condition.

Samson, J. E.

doi: 10.1177/002029406800100401pmid: N/A

Adams, B. E.

doi: 10.1177/002029406800100402pmid: N/A

Bosselaar, H.; van Riemsdijk, A. J.

doi: 10.1177/002029406800100403pmid: N/A

Spencer, J.

doi: 10.1177/002029406800100404pmid: N/A

The ergonomics of instrument panels is very important, and will continue to be so for some considerable time to come if we assume that man will retain executive responsibility for the majority of industrial enterprises.The reason why research in this area is limited is discussed, and then such research as seems relevant in order either to suggest guiding principles for successful panel design, or to indicate where research is needed to complete our knowledge is briefly outlined.

Gall, M. H. W.; Elias, D. G.

doi: 10.1177/002029406800100405pmid: N/A