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Modeling microbial kinetics as a function of temperature: identification of the growth/inactivation interface

IFAC Proceedings Volumes 2010年第6期43卷 519-524页

作者： E. Van Derlinden J.F. Van Impe CPMF2 - Flemish Cluster Predictive Microbiology in Foods -www.cpmf2.be BioTeC - Chemical and Biochemical Process Technology and Control Department of Chemical Engineering Katholieke Universiteit Leuven W. de Croylaan 46 B-3001 Leuven Belgium

A previous implementation of dynamic experiments for the estimation of the parameters of the Cardinal Temperature Model with Inflection (CTMI), which describes the temperature effect on the microbial growth rate, revealed that the maximum growth temperature ( T max ) can only be estimated accurately when temperatures close to the true T max are included. As such, a reliable T max estimate is required at the beginning of the OED/PE implementation. Here, alternative experiments in which the temperature exceeds the growth/inactivation interface are evaluated. Results from the simulation study show that the accuracy and reliability of the T max estimate depends on the selected temperature profile. A very accurate and realistic T max value is obtained from experiments with an initial temperature slightly lower than the true T max . When the dynamic temperature starts at temperatures above T max , a larger uncertainty and variability is observed. From this, it can be concluded that information with respect to growth at temperatures close to T max is required for an accurate and reliable T max estimate. In a second step, two dynamic temperature profiles are implemented in a computer controlled bioreactor. The experimental data do not result in an accurate and reliable estimation of T max . Additional dynamic experiments are required to evaluate the proposed experimental set-up.

关键词： predictive microbiology maximum growth temperature cardinal temperature model dynamic experiments growth/inactivation interface parameter estimation

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Robust stabilization of interval plants using Kronecker summation method

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WSEAS Transactions on Systems 2010年第9期9卷 917-926页

作者： Matušů, Radek Prokop, Roman Matejičková, Katarína Bakošová, Monika Department of Automation and Control Engineering Faculty of Applied Informatics Tomas Bata University in Zlín Nad Stráněmi 4511 76005 Zlín Czech Republic Department of Information Engineering and Process Control Faculty of Chemical and Food Technology Slovak University of Technology in Bratislava Radlinského 9 81237 Bratislava Slovakia

This paper deals with design of continuous-time robustly stabilizing Proportional-Integral (PI) controllers for interval systems using the combination of Kronecker summation method, sixteen plant theorem and an algebraic approach to controller tuning. The effectiveness and practical applicability of the proposed method is demonstrated in both simulation and real experiments including control of a third order nonlinear electronic plant.

关键词： Continuous time systems

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Theoretical analysis of chirp excitation of contrast agents

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Physics Procedia 2010年第1期3卷 743-747页

作者： Euan Barlow Anthony J. Mulholland Alison Nordon Anthony Gachagan Department of Mathematics University of Strathclyde 26 Richmond Street Glasgow G1 1XH UK WestCHEM Department of Pure and Applied Chemistry Centre for Process Analytics and Control Technology (CPACT) University of Strathclyde Glasgow G1 1XL UK Department of Electronic and Electrical Engineering The Centre for Ultrasonic Engineering (CUE) University of Strathclyde GlasgowG1 1XW UK

Analytic expressions are found for the amplitude of the first and second harmonics of the Ultrasound Contrast Agent’s (UCA’s) dynamics when excited by a chirp. The dependency of the second harmonic amplitude on the system parameters, the UCA shell parameters, and the insonifying signal parameters is then investigated. It is shown that optimal parameter values exist which give rise to a clear increase in the second harmonic component of the UCA’s motion.

关键词： Ultrasound contrast agent Chirp Second harmonic Theoretical Small parameter perturbation

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Sensitivity Analysis of a Two-dimensional Microbiological Risk Assessment

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IFAC Proceedings Volumes 2010年第6期43卷 323-328页

作者： Pieter Busschaert Annemie H. Geeraerd Mieke Uyttendaele Jan F. Van Impe CPMF2 - Flemish Cluster Predictive Microbiology in Foods -http://www.cpmf2.be BioTeC - Chemical and Biochemical Process Technology and Control Department of Chemical Engineering Katholieke Universiteit Leuven Leuven Belgium MeBioS - Division of Mechatronics Biostatistics and Sensors Department of Biosystems (BIOSYST) Katholieke Universiteit Leuven Leuven Belgium Laboratory of Food Microbiology and Food Preservation Department of Food Safety and Food Quality Ghent University Ghent Belgium

Quantitative microbiological risk assessment aims at estimating the risk of illness that is related to a certain pathogen and food type combination through the use of simulations. A recent trend can be seen in which uncertainty about the risk estimate is characterized separately from variability, generally implemented by means of a two-dimensional Monte Carlo simulation. This research aims at identifying the key parameters that contribute to the obtained risk while keeping the effect of uncertainty and variability separated using a methodology based on analysis of variance. The risk related to Listeria monocytogenes in meat preparations is used as a case study. It is found that uncertainty about the correct dose-response model is determining the output most. Also the variability distribution of storage duration and storage temperature have a major effect on the final risk. Furthermore, uncertainty about the location of the storage duration distribution is an important factor determining risk. These findings illustrate how the methodology proposed in this research enables identification of the relative importance of all model parameters such as temperature, storage duration, food contamination, etc., and also comparison of the impact of variability versus uncertainty about model parameters on the final risk estimate.

关键词： Quantitative microbiological risk assessment sensitivity analysis variability uncertainty analysis of variance L. monocytogenes meat preparations

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Describing the heterogeneous heat response of E. coli with a subpopulation type model

Describing the heterogeneous heat response of E. coli with a...

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15th IFAC Symposium on System Identification, SYSID 2009

作者： Van Derlinden, E. Van Impe, J.F. BioTeC - Chemical and Biochemical Process Technology and Control Section Department of Chemical Engineering Katholieke Universiteit Leuven W. de Croylaan 46 B-3001 Leuven Belgium

ISBN: (纸本)9783902661470

Previous work showed that the exponential growth phase of E. coli K12 MG1655, grown in Brain Heart Infusion broth at temperatures close to its maximum temperature for growth is disturbed. Based on plate count data, microscopic images and literature, the existence of a heat resistant subpopulation was hypothesized [21]. This hypothesis is here mathematically validated by means of a heterogeneous modeling approach. Two subpopulations are considered: one sensitive population and one population with increased heat tolerance. A large fraction of the initial population inactivates while the remaining smaller fraction is able to resist (or adapt to) the inimical temperature and grows. A heterogeneous model that encloses growth (resistant population) and inactivation (sensitive population) is used to describe the global population dynamics. Most experimental data can be predicted when taking into account parameter uncertainty via Monte Carlo simulation. The heterogeneous modeling approach yields accurate description of disturbed growth curves at super optimal temperatures, except for high initial cell densities. This study confirms the existence of a (small) heat resistant subpopulation in typical inoculum cultures of Escherichia coli K12 MG1655. © 2009 IFAC.

关键词： Escherichia coli

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Soft sensor based nonlinear control of a chaotic reactor

Soft sensor based nonlinear control of a chaotic reactor

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作者： Rama Rao, Karri Rao, D.P. Venkateswarlu, Ch. Chemical Engineering Department Indian Institute of Technology Delhi New Delhi - 110016 India Process Dynamics and Control Group Chemical Engineering Sciences Indian Institute of Chemical Technology Hyderabad - 500 007 India

ISBN: (纸本)9783902661661

control of nonlinear systems exhibiting complex dynamic behavior is a challenging task because such systems present a variety of behavioral patterns depending on the values of physical parameters and intrinsic features. Understanding the behavior of the nonlinear dynamic systems and controlling them at the desired conditions is important to enhance their performance. In this work, a soft sensor based nonlinear controller strategy is presented and applied to control a chemical reactor that exhibit multi-stationary unstable behavior, oscillations and chaos. In this strategy, an extended kalman filter is designed to serve as a soft sensor that provides the estimates of unmeasured process states. These states are used as inferential measurements to the nonlinear controller that is designed in the framework of globally linearizing control. The results evaluated for stabilizing the reactor for different conditions including deterministic and stochastic disturbances show the better performance of the soft sensor based nonlinear control strategy over that of a PID controller with modified feedback mechanism.

关键词： controllers

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Industrial implementation of a coordinator MPC for maximizing throughput at a large-scale gas plant

Industrial implementation of a coordinator MPC for maximizin...

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作者： Aske, Elvira Marie B. Strand, Stig Skogestad, Sigurd Department of Chemical Engineering Norwegian University of Science and Technology N-7491 Trondheim Norway StatoilHydro R and D Integrated Operations and Process Control N-7005 Trondheim Norway

ISBN: (纸本)9783902661548

An industrial implementation of a coordinator MPC to maximize throughput at the large-scale Kårstø gas plant is described. The "coordinator MPC" coordinates the flows through the network and not the local MPCs. It uses as degrees of freedom (MVs) the flows not used by the local MPCs (feeds, crossovers), and maximizes the throughput subject to the keeping the remaining capacities in all units zero or positive. A key idea is to use the local MPCs to estimate the remaining capacities in the units (Aske et al., 2008). Although not fully implemented, the coordinator MPC is found to be a promising tool for implementing maximum throughput.

关键词： Gas plants

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process analytical technology and compensating for nonlinear effects in process spectroscopic data for improved process monitoring and control

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Biotechnology Journal 2009年第5期4卷 610-619页

作者： Chen, Zengping Morris, Julian Centre for Process Analytics and Control Technology School of Chemical Engineering and Advanced Materials Newcastle University Newcastle upon Tyne NE1 7RU United Kingdom

Robust fit-for-purpose multivariate calibration models are of critical importance to on-line/in-line quantitative monitoring of bio-chemicals and pharmaceuticals using spectroscopic instruments. Unlike in off-line assays, the spectroscopic measurements in on-line/in-line real-time applications are almost inevitably subjected to variations in measurement conditions (e.g. temperature) and samples' physical properties (e.g. cell density, particle size, sample compactness), which can invalidate the assumption of a linear relationship between the spectroscopic measurements and the concentrations of the target chemical components. This Biotech Highlight discusses the effects of such variations on spectroscopic measurements, and presents an overview of recent work on modelling and correcting of the detrimental effects of variations in measurement conditions and samples' physical properties.A number of application studies to complex datasets and an industrial plant demonstrate the methodologies and algorithms discussed.

关键词： Multiplicative light scattering Multivariate linear calibration Near infrared spectroscopy Optical path length estimation and correction Temperature‐induced spectral variations

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Corrigendum to "A new method for assessing domino effect in chemical process industry" [J. Hazard. Mater. 182 (2010) 416-426]

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Journal of hazardous materials 2010年第1-3期184卷 877页

作者： Bahman Abdolhamidzadeh Tasneem Abbasi D Rashtchian S A Abbasi Center for Process Design Safety and Loss Prevention Department of Chemical and Petroleum Engineering Sharif University of Technology Tehran Iran. Center for Pollution Control and Environmental Engineering Pondicherry University Kalapet Pondicherry 605 014 India. Center for Pollution Control and Environmental Engineering Pondicherry University Kalapet Pondicherry 605 014 India. Electronic address: prof.s.a.abbasi@***.

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Robust Proportional-Integral control of a laboratory model using Programmable Logic controller SIMATIC S7-300

Robust Proportional-Integral control of a laboratory model u...

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6th IFAC Symposium on Robust control Design, ROCOND'09

作者： Matušů, Radek Vaneková, Katarína Prokop, Roman Bakošová, Monika Department of Automation and Control Engineering Faculty of Applied Informatics Tomas Bata University in Zlín Nad Stráněmi 4511 76005 Zlín Czech Republic Department of Information Engineering and Process Control Faculty of Chemical and Food Technology Slovak University of Technology in Bratislava Radlinského 9 81237 Bratislava Slovakia

ISBN: (纸本)9783902661456

The main aim of the contribution is to present a possible approach to design of simple Proportional-Integral (PI) robust controllers and subsequently to demonstrate their applicability during control of a laboratory model with uncertain parameters through the Programmable Logic controller (PLC) SIMATIC S7-300 by Siemens Company. The proposed and utilized synthesis consists of two steps - the former one is a determination of controller parameters area, which ensures the robustly stable control loop and which is based on the computing/plotting the stability boundary locus while the latter one lies in the final choice of the controller itself relying on algebraic techniques. The basic theoretical parts are followed by laboratory experiments in which the 3rd order nonlinear electronic model has been successfully controlled in various working points. © 2009 IFAC.

关键词： Programmable logic controllers

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