Publications
212 results found
Thornhill NF, Oettinger M, Fedenczuk P, 1998, Performance assessment and diagnosis of refinery control loops, 3rd International Conference on Foundations of Computer-Aided Process Operations, Publisher: AMER INST CHEMICAL ENGINEERS, Pages: 373-379, ISSN: 0065-8812
- Author Web Link
- Open Access Link
- Cite
- Citations: 6
Zhang J, Zhang S, Thornhill N, 1998, A governing equation based fault detection and diagnosis algorithm and its application in a chemical plant, Pages: 2472-2476, ISSN: 0743-1619
This paper describes a governing equation fault detection and diagnosis algorithm, which is based on Kramer (1987) and extended to deal with multiple faults. The algorithm is specifically designed to overcome disturbances and uncertainties in the process which might result in diagnostic instability. The approach is used to detect and/or diagnose the following faults: sensor faulty status of fails-high and fails-low, sticking valve, plant leaks, and other unanticipated or novel faults. The algorithm was installed on a distributed control system (DCS) of a PET plant in Dec. 1995, and continues to be used thus demonstrating the success of the fault detection and diagnosis approach. © 1998 AACC.
Sabry M, Thornhill NF, Midwinter JE, 1997, An analytical approach to charging mechanisms using control theory, ISSN: 0963-3308
In this paper we suggest how control theory may be used to model and analytically analyse telecommunication network charging mechanisms. We propose a control theory model which was used to analyse the dynamic (also known as 'Smart Market' or 'Free Market') charging scheme. We show how the analytical model was formalised and analysed to determine the long term or Steady State (SS), in control theory terminology, and short term or transient responses of the mechanism. We show how the system's performance varies as the parameters change. We also discuss the limitations of this method of analysis and in particular how this affects the results of the dynamic charging scheme analysis.
Thornhill NF, Hagglund T, 1997, Detection and diagnosis of oscillation in control loops, CONTROL ENGINEERING PRACTICE, Vol: 5, Pages: 1343-1354, ISSN: 0967-0661
- Author Web Link
- Open Access Link
- Cite
- Citations: 109
Chandwani RM, Pate ME, Savery J, et al., 1997, The use of principal component analysis as a database mining tool for the exploratory diagnosis of chromatographic processes, BIOPROCESS ENGINEERING, Vol: 17, Pages: 229-234, ISSN: 0178-515X
- Author Web Link
- Cite
- Citations: 3
Gregory ME, Thornhill NF, 1997, The effects of aeration and agitation on the measurement of yeast biomass using a laser turbidity probe, BIOPROCESS ENGINEERING, Vol: 16, Pages: 339-344, ISSN: 0178-515X
- Author Web Link
- Cite
- Citations: 9
Dehghani M, Bulmer M, Gregory ME, et al., 1996, On-line recognition of CO<inf>2</inf>exit gas profiles for operational harvesting time of intracellular enzyme products from S. cerevisiae, Bioprocess and Biosystems Engineering, Vol: 16, Pages: 50-55, ISSN: 1615-7591
This paper concerns the recognition of significant events in the trends from CO2exit gas profiles of a S.cerevisiae fermentation. Distinct changes in the on-line monitored variable, CO2exit gas concentration, are used to recognise identifiable phases of glucose depletion, biomass formation and the onset of intracellular enzyme production. Process automation for the harvesting of some intracellular enzyme products from S. cerevisiae is considered using on-line recognition of CO2exit gas peaks.
Dehghani M, Bulmer M, Gregory ME, et al., 1996, On-line recognition of CO2 exit gas profiles for operational harvesting time of intracellular enzyme products from S-cerevisiae, BIOPROCESS ENGINEERING, Vol: 16, Pages: 50-55, ISSN: 0178-515X
- Author Web Link
- Cite
- Citations: 2
Thornhill NF, Hutchinson RJ, Haughie BT, 1996, A probability chart for statistical process analysis, with applications, JOURNAL OF PROCESS CONTROL, Vol: 6, Pages: 161-167, ISSN: 0959-1524
- Author Web Link
- Open Access Link
- Cite
- Citations: 1
Bogle IDL, Cockshott AR, Bulmer M, et al., 1996, A process systems engineering view of biochemical process operations, COMPUTERS & CHEMICAL ENGINEERING, Vol: 20, Pages: 943-949, ISSN: 0098-1354
- Author Web Link
- Cite
- Citations: 9
Thornhill NF, Sadowski R, Davis JR, et al., 1996, Practical experiences in refinery control loop performance assessment, UKACC International Conference on Control '96, 2-5 September 1996, Pages: 175-180, ISSN: 0537-9989
The paper presents an example of the application of a control loop performance assessment technique in a refinery setting and diagnoses the causes of oscillations in flow loops.
DEHGHANI M, BULMER M, GREGORY ME, et al., 1995, MEASUREMENT VARIABILITY ANALYSIS FOR FERMENTATION PROCESS ASSAYS, BIOPROCESS ENGINEERING, Vol: 13, Pages: 239-243, ISSN: 0178-515X
- Author Web Link
- Cite
- Citations: 6
TURNER C, GREGORY ME, THORNHILL NF, 1994, CLOSED-LOOP CONTROL OF FED-BATCH CULTURES OF RECOMBINANT ESCHERICHIA-COLI USING ONLINE HPLC, BIOTECHNOLOGY AND BIOENGINEERING, Vol: 44, Pages: 819-829, ISSN: 0006-3592
- Author Web Link
- Cite
- Citations: 42
GREGORY ME, KEAY PJ, DEAN P, et al., 1994, A VISUAL PROGRAMMING ENVIRONMENT FOR BIOPROCESS CONTROL, JOURNAL OF BIOTECHNOLOGY, Vol: 33, Pages: 233-241, ISSN: 0168-1656
- Author Web Link
- Cite
- Citations: 20
THORNHILL NF, MANELA M, CAMPBELL JA, et al., 1994, 2 METHODS OF SELECTING SMOOTHING SPLINES APPLIED TO FERMENTATION PROCESS DATA, AICHE JOURNAL, Vol: 40, Pages: 716-725, ISSN: 0001-1541
- Author Web Link
- Cite
- Citations: 5
Turner C, Thornhill NF, Fish NM, 1993, A novel method for the on-line analysis of fermentation broth using a sampling device, microcentrifuge and HPLC, Biotechnology Techniques, Vol: 7, Pages: 19-24, ISSN: 0951-208X
This paper describes a novel system for on-line sampling and analysis of whole broth from a fermenter. The system comprises a steam sterilisable sampling device, high speed microcentrifuge and HPLC. We present results characterising the separation efficiency of the microcentrifuge under different conditions, and illustrate the system with glucose and acetate data from an Escherichia coli fermentation using the system. The on-line measurements have been confirmed by off-line analysis. © 1993 Science & Technology Letters.
ROYCE PN, THORNHILL NF, 1992, ANALYSIS OF NOISE AND BIAS IN FERMENTATION OXYGEN-UPTAKE RATE DATA, BIOTECHNOLOGY AND BIOENGINEERING, Vol: 40, Pages: 634-637, ISSN: 0006-3592
- Author Web Link
- Cite
- Citations: 16
Royce PN, Thornhill NF, 1992, Analysis of noise and bias in fermentation oxygen uptake rate data., Biotechnol Bioeng, Vol: 40, Pages: 634-637, ISSN: 0006-3592
The calculation of many derived fermentation variables such as the respiratory quotient (RQ) and mass transfer coefficient (K(L)a) requires the differences between the molar percentages of oxygen and carbon dioxide in the fermentor inlet and exit gas, called the %OUR and %CER. Noise and bias in %CER data is of order that in the exit gas carbon dioxide analysis. However, the relative amount of noise in the %OUR is one to two orders of magnitude greater than the noise in the raw oxygen analyses because the %OUR is calculated as a small difference between two large quantities. The noise in the %OUR is white with a Gaussian amplitude probability distribution of absolute standard deviation 0.0145. A chi-square filter of the %OUR data is shown to considerably improve the quality of the calculated RQ and K(L)a for a fermentation of Streptomyces clavuligerus.
Stone KM, Roche FW, Thornhill NF, 1992, DRY WEIGHT MEASUREMENT OF MICROBIAL BIOMASS AND MEASUREMENT VARIABILITY ANALYSIS, BIOTECHNOLOGY TECHNIQUES, Vol: 6, Pages: 207-212, ISSN: 0951-208X
MARSHALL CT, THORNHILL NF, LILLY MD, et al., 1992, THE DESIGN AND IMPLEMENTATION OF A COMPARATIVE REASONING TOOL FOR FERMENTATIONS, 2nd IFAC Symposium on Modeling and Control of Biotechnical Processes 1992/5th International Conference on Computer Applications in Fermentation Technol, Publisher: PERGAMON PRESS LTD, Pages: 283-286, ISSN: 0962-9505
GREGORY ME, THORNHILL NF, 1992, USE OF A GRAPHICAL PROGRAMMING ENVIRONMENT FOR THE RAPID DEVELOPMENT OF CUSTOM SOFTWARE FOR FERMENTATION PROCESS CONTROL, 2nd IFAC Symposium on Modeling and Control of Biotechnical Processes 1992/5th International Conference on Computer Applications in Fermentation Technol, Publisher: PERGAMON PRESS LTD, Pages: 231-234, ISSN: 0962-9505
STONE KM, THORNHILL NF, ROCHE FW, et al., 1992, A METHOD OF USING OFF-LINE MEASUREMENTS IN AN ON-LINE ESTIMATOR OF BIOMASS CONCENTRATION FOR A PENICILLIN FERMENTATION, AND ITS EFFECTS ON THE QUALITY OF THE ESTIMATES, 2nd IFAC Symposium on Modeling and Control of Biotechnical Processes 1992/5th International Conference on Computer Applications in Fermentation Technol, Publisher: PERGAMON PRESS LTD, Pages: 101-106, ISSN: 0962-9505
- Author Web Link
- Cite
- Citations: 1
TURNER C, THORNHILL NF, FISH NM, 1992, ON-LINE SAMPLING AND ANALYSIS OF FERMENTATION BROTH USING A NOVEL SAMPLING DEVICE, MICROCENTRIFUGE AND HPLC, 2nd IFAC Symposium on Modeling and Control of Biotechnical Processes 1992/5th International Conference on Computer Applications in Fermentation Technol, Publisher: PERGAMON PRESS LTD, Pages: 339-342, ISSN: 0962-9505
ROCHE FW, THORNHILL NF, STONE KM, et al., 1992, FAULT DETECTION AND IDENTIFICATION IN FERMENTERS, 2nd IFAC Symposium on Modeling and Control of Biotechnical Processes 1992/5th International Conference on Computer Applications in Fermentation Technol, Publisher: PERGAMON PRESS LTD, Pages: 323-326, ISSN: 0962-9505
ROYCE PNC, THORNHILL NF, 1991, ESTIMATION OF DISSOLVED CARBON-DIOXIDE CONCENTRATIONS IN AEROBIC FERMENTATIONS, AICHE JOURNAL, Vol: 37, Pages: 1680-1686, ISSN: 0001-1541
- Author Web Link
- Cite
- Citations: 69
Thornhill NF, 1990, Detecting Faults in Fermentation Processes, Computing and Control Engineering Journal, Vol: 1, Pages: 187-192, ISSN: 0956-3385
Fermentation processes are involved in the production of Pharmaceuticals (e.g. antibiotics), chemicals and bulk enzymes (e.g. citric acid, washing-powder enzymes), numerous foods and beverages, waste water treatment and in agriculture (e.g. silage). There are problems, particularly of process complexity and variability, that make fault detection and analysis in fermentation somewhat more difficult than in other process industries. The intention of this article is to illustrate present industrial practices of'high-value' fermentation processes, to survey the techniques that are beginning to be applied and to highlight what seem to be the most relevant developments. © 1990, The Institution of Electrical Engineers. All rights reserved.
ROYCE PNC, ANDERSON MM, FISH NM, et al., 1989, THE USE OF CARBON-DIOXIDE EVOLUTION RATE IN CONSISTENCY CHECKING OTHER FERMENTER SENSOR OUTPUTS, 4TH INTERNATIONAL CONF ON COMPUTER APPLICATIONS IN FERMENTATION TECHNOLOGY ( ICCAFTA ), Publisher: ELSEVIER APPL SCI PUBL LTD, Pages: 443-447
- Author Web Link
- Cite
- Citations: 1
THORNHILL NF, FUNG MYP, ROCHE FW, et al., 1989, FERMENTATION FAULT-DIAGNOSIS USING ANALYTICAL REDUNDANCY, 4TH INTERNATIONAL CONF ON COMPUTER APPLICATIONS IN FERMENTATION TECHNOLOGY ( ICCAFTA ), Publisher: ELSEVIER APPL SCI PUBL LTD, Pages: 455-459
- Author Web Link
- Cite
- Citations: 1
FISH N, THORNHILL N, 1988, MONITORING AND CONTROL OF FERMENTATION, CHEMICAL ENGINEER-LONDON, Pages: 31-&, ISSN: 0302-0797
- Author Web Link
- Cite
- Citations: 1
Fish N, Thornhill N, 1988, Monitoring and control of fermentation., CHEM. ENGR., ISSN: 0302-0797
Parameters influencing the fermentation process are defined. A simple model for microbial growth is given by a combination of the Monod equation (describing the dependence of the growth rate on the concentration of a limiting nutrient) and an equation associated with the consumption of that nutrient. Control of fermentation achieved by changing the chemical and physical environment in the reactor is discussed. Problems encountered in the development of new sensors for measurement of process variables are considered. The use of an efficient estimation filtering algorithm, such as an adaptive Kalman-Bucy filter, is discussed.
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.