Volume 2
Worldwide Scientists
New Books
Forthcoming Events
18th International Symposium "Bioprocess Systems'05"
New On-Line Journal
In Memoriam
Modelling and Optimization of Biotechnological Systems
Application of a Fuzzy Neural Network for Modeling of the Mass-Transfer Coefficient in a Stirred Tank Bioreactor1-7
Mitko Petrov, Tatiana Ilkova, Stoyan Tzonkov, Uldis Viesturs
[ +/- abstract ][ full text ]
A type of a fuzzy neural network for mathematical modeling of the volumetric mass-transfer coefficient is presented in the paper. Performed investigations show that the presented fuzzy neural network can be successfully used for modeling of such a complex process, like mass-transfer.
Modelling of Functional States during Saccharomyces cerevisiae Fed-batch Cultivation8-16
Tania Pencheva, Iasen Hristozov, Dirk Huell, Bernd Hitzmann, Stoyan Tzonkov
[ +/- abstract ][ full text ]
An implementation of functional state approach for modelling of yeast fed-batch cultivation is presented in this paper. Using of functional state modelling approach aims to overcome the main disadvantage of using global process model, namely complex model structure and big number of model parameters, which complicate the model simulation and parameter estimation. This approach has computational advantages, such as the possibility to use the estimated values from the previous state as starting values for estimation of parameters of a new state. The functional state modelling approach is applied here for fedbatch cultivation of Saccharomyces cerevisiae. Four functional states are recognised and parameter estimation of local models is presented as well.
Generalized Net Model of Brevibacterium flavul 22LD Fermentation Process17-23
Olympia Roeva, Tania Pencheva
[ +/- abstract ][ full text ]
In order to render the specific peculiarities of the fermentation processes, as well as to avoid the complexity of mathematical description with systems of differential equations, the elaboration of some new methods and approaches for their modelling and control is predetermined. As a new, alternative approach for modelling of fermentation processes, an application of generalized nets is presented in this paper. The theory of generalized nets is applied to the fermentation process of Brevibacterium flavul 22LD for L-lysine production. A generalized net model of considered process is developed. For comparison and completeness, model with differential equations is also provided. The generalized nets model developed for the fed-batch cultivation of Brevibacterium flavul 22LD allows changing the concentration of the feeding solution and the aeration rate. In this way some inhibition effects are prevented and a possibility for optimal carrying out of the considered fermentation process is provided.
Equivalent Models, Maximum Principle and Optimal Control of Continuous Biotechnological Process: Peculiarities and Problems24-29
Yuri Pavlov
[ +/- abstract ][ full text ]
A Brunovsky normal form model is introduced by using some differential geometry results for reduction of a non-linear kinetic model into equivalent linearised form. The transformed model is implemented for optimal control determination with the maximum principle.
Control of Biotechnological Systems
Optimal Feed Rate Control of Escherichia coli Fed-batch Fermentation30-36
Olympia Roeva, Stoyan Tzonkov
[ +/- abstract ][ full text ]
In this paper an optimal control algorithm for E. coli fed-batch fermentation has been developed. A simple material balance model is used to describe the E. coli fermentation process. The optimal feed rate control of a primary metabolite process is studied and a biomass production is used as an example. An optimization of a fed-batch fermentation process is usually done using the calculus of variations to determine an optimal feed rate profile. In the optimal control literature the problem is formulated as a free final time problem where the control objective is to maximise biomass at the end of the process. The obtained optimal feed rate profile consists of sequences of maximum and minimum feed rates. The obtained results are used for optimization of E. coli fed-batch fermentation and the presented simulations show a good efficiency of the developed optimal feed rate profile.
Knowledge-Based Control Systems via Internet Part I. Applications in Biotechnology37-48
Svetla Vassileva, Georgi Georgiev, Silvia Mileva
[ +/- abstract ][ full text ]
An extensive approach towards the dissemination of expert knowledge and coordination efforts to distributed points and seamless integration of control strategies applied to distributed yet identical systems is crucial to enhance overall efficiency and operational costs. Application of Knowledge-Based Control System via Internet will be very efficient especially in biotechnology, because many industrial bioprocesses, based on the same technological principles, are distributed in the whole world. Brewing industry oriented practical solutions illustrate this approach.
Implementation of Sliding Mode Controller with Boundary Layer for Saccharomyces cerevisiae Fed-batch Cultivation49-53
Iasen Hristozov, Tania Pencheva, Dirk Huell, Christine Klockow, Bernd Hitzmann, Stoyan Tzonkov
[ +/- abstract ][ full text ]
An implementation of sliding mode control for yeast fed-batch cultivation is presented in this paper. Developed controller has been implemented on two real fed-batch cultivations of Saccharomyces cerevisiae. The controller successfully stabilizes the process and shows a very good performance at high input disturbances.
Bioprocess Systems
Biotechnological Methods for Precise Diagnosis of Methicillin Resistance in Staphylococci54-64
Aija Žileviča, Tatjana Tračevska, Uldis Viesturs
[ +/- abstract ][ full text ]
Antimicrobial resistance is one of the most urgent problems in medicine nowadays. The purpose of the study was to investigate the microorganisms resistant to first-line antimicrobials, including gram-positive cocci, particularly the methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococci, the major agents of nosocomial infections. Owing to the multi-resistance of these agents, precise diagnosis of the methicillin resistance of Staphylococci is of greatest clinical importance. It is not enough to use only conventional microbiological diagnostic methods. Biotechnological methods should be also involved. In our studies, the following methicillin resistance identification methods were used: the disk diffusion method, detection of the mecA gene by PCR, E-test and Slidex MRSA test. For molecular typing, PFGL, RAPD tests and detection of the coa gene were used. All the MRS strains were multiresistant to antibacterials. No vancomycine resistance was registered.
Kinetics of Enzyme Biodegradation of New Synthesized Copolymers65-69
Lubov Yotova, Natalia Toncheva, Rosa Mateva
[ +/- abstract ][ full text ]
Block copolymers of the poly-(hexanlactam)-co-block-poly-(δ-valerolactone) from ABA-type were synthesized via anionic polymerization of hexanlactam (HL) with the sodium salt of hexanlactam (Na-HL) as an initiator and polymeric activator (PAC). PAC, on the base of poly-δ-valerolactone (PVL), was used as a soft central block. Synthetic PVL is very attractive biomaterial - nontoxic, biocompatibility and biodegradable polyester[5-8]. Modification of HL with PVL, renders these system biodegradable[1]. Isolated copolymers were characterized by various spectroscopic techniques. The effect of the chemical and physical structure of the synthesized block copolymers on the biodegradation was investigated. Biodegradation of block copolyester amides was studied by means of lipase and involves the enzymatic hydrolysis of ester groups in PVL.
Ecotoxicological Assessment of Water and Sediment Pollution of the Iskar River bellow Samokov70-75
Ivan Diadovski, Yana Raykovska, Niels De Pauw, Diederik Rousseau
[ +/- abstract ][ full text ]
A system of integral ecological indices has been worked out to assess the level of pollution of water and sediments with hazardous substances. A model for the dynamics of the integral index for water and sediments pollution is proposed. This index was applied for ecotoxicological assessment of water and sediments pollution of the Iskar river bellow Samokov. A modification method on time series analysis is applied.
Biomedical Systems
Fast Electrocardiogram Amplifier Recovery after Defibrillation Shock76-84
Ivan Dotsinsky, Tatyana Neycheva
[ +/- abstract ][ full text ]
A procedure for fast ECG amplifier recovery after defibrillation shocks was developed and simulated in the MATLAB environment. Exponentially decaying post-shock voltages have been recorded. Signals from the AHA database are taken and mixed with the recorded exponential disturbances. The algorithm applies moving averaging (comb filter) on the compound input signal, thereby obtaining the samples of the disturbance. They are currently subtracted from the input signal. The results obtained show that its recovery is practically instantaneous.
Dynamic Model of Intensive Care Unit Workflow based on Generalized Net85-92
Mikhail Matveev, Krassimir Atanassov, Evelina Pazvanska, Violeta Tasseva
[ +/- abstract ][ full text ]
Every intensive care unit (ICU) admits critically ill patients with disturbed vitally important functions. Time is a critical factor with such patients and the optimum behaviour of the medical team is decisive. They require optimised distribution of the staff and material resources, hence an adequate model of the structure and activities in an ICU is needed. Such a model was built using generalized nets (GNs).
The workflow presented as a GNs-model is based on principles and prerequisites typical of ICU. Structure of the information included in the model: the updated information on the state of the ICU (occupancy rate of the hospital beds, the state of the patients, the available physicians and nurses, and their distribution for the concrete patients, available material facilities) is supported by specialised databases. There also exists a database of protocols with prescriptions for diagnostic and therapeutic conduct. The goal attained with GNs is: solution for the admission and servicing of patients at the ICU in a dynamically changing situation at any moment of the night and day.
The dynamic workflow model in ICU in the form of a GNs is an adequate approach for optimum distribution of the resources and optimum conduct in the care for patients with severe disorders of the vital functions.
Using Glucose Tolerance Tests to Model Insulin Secretion and Clearance93-106
Anthony Shannon
[ +/- abstract ][ full text ]
The purpose of the studies described in this paper is to develop theoretically and to validate experimentally mathematical compartment models which can be used to predict plasma insulin levels in patients with diabetes mellitus (DM). In the case of Type 2 Diabetes Mellitus (T2DM), the C-peptide levels in the plasma were measured as part of routine glucose tolerance tests in order to estimate the prehepatic insulin secretion rates. In the case of Type 1 Diabetes Mellitus (T1DM), a radioactive labelled insulin was used to measure the absorption rate of insulin after a subcutaneous injection of insulin. Both models gave close fits between theoretical estimates and experimental data, and, unlike other models, it is not necessary to seed these models with initial estimates.
Generalized Net Model of Human Hematopoietic System107-114
Vichren Chakarov, Anthony Shannon, Krassimir Atanassov
[ +/- abstract ][ full text ]
Generalized Nets (GNs) are extensions of Petri nets and other their modifications. GNs are suitable tool for modelling of parallel processes. In a series of papers the authors describe the ways of functioning of the separate systems in the human body. In the present one a GN-model of the human hematopoietic system is described and its applications are discussed.

© 2005, BAS, Institute of Biophysics and Biomedical Engineering