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C Jakeman

Publications and source records attributed to C Jakeman.

3 recordsLinked to original sources
PubMed2002

Improving the development of event-driven control systems in the batch processing industry. A case study.

This paper presents the results of an academia-industry collaborative project whose main objective was to test novel techniques for the development of event-driven control systems in the batch processing (e.g., pharmaceutical, fine chemicals, food) industries. Proposed techniques build upon industrial standards and focus on (i) formal synthesis of phase control logic and its automatic translation into procedural code, and (ii) verification of the complete discrete-event control system via dynamic simulation. In order to test the techniques in an engineering environment, a complete discrete-event control system was produced for a benchmark batch process plant based on a standard development method employed by one of the industrial partners. The control system includes functional process specification, control architecture, distributed control system (DCS) proprietary programming code for procedural control at equipment, unit, and process cell levels, and human-machine interfaces: A technical assessment of the development method and the obtained control system was then carried out. Improvements were suggested using the proposed techniques in the specification, code generation and, verification steps. The project assessed the impact of these techniques from both an engineering and economic point of view. Results suggest that the introduction of computer aided engineering (CAE) practices based on the benchmarked techniques and a structured approach could effect a 75% reduction of errors produced in the development process. This translates into estimated overall savings of 7% for green-field projects. Figures were compared with other partners' experience. It is expected that the work load on a given project will shift, increasing the load on process engineers during the specification stage and decreasing the load on the software engineers during the code writing.

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PubMed1990

The complications of trabeculectomy (a 20-year follow-up).

The complications of trabeculectomy were studied in two groups of patients taken from a stable white population. The first group who had had their operation when it was first introduced 22 years ago, had been previously treated with prolonged medication, the second group had been operated upon recently and had had short-term pre-operative medication. This study confirmed that trabeculectomy predictably reduces the intraocular pressure to within the accepted normal range and that the pressure level below which the intraocular pressure could not be expected to fall was congruent to 14 mm/Hg. It also revealed that although some post operative abnormality was noted in two-thirds of the patients there were no long term problems which could be related to any operative or immediately post-operative complications, including shallow anterior chambers, uveitis and hyphaema. However, there was a long term reduction in the visual acuity and visual fields of about one-third of the patients, which was not related to cataract formation, macular problems, the height of the preoperative intraocular pressure, the amount by which this fell as a result of the surgery, or the amount, length or type of preoperative medication given before the operation. Although there was some increase in cataracts throughout the whole long term group this was mainly in those who had cataract prior to surgery; the increase was not related to operations or any other factor other than corneo-lenticular contact post-operatively.

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