Volume 3
Editorial
Worldwide Scientists
Forthcoming Events
First call for the 19th International Symposium "Bioprocess Systems 2007 - BioPS'07"
Modelling and Optimization of Biotechnological Systems
On the Use of Computer Algebra Systems and Enclosure Methods in the Modelling and Optimization of Biotechnological Processes1-9
Svetoslav Markov
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This survey paper aims to promote certain novel mathematical tools, such as computer algebra systems, enclosure methods and interval analysis, to the mathematical modelling and optimization of biotechnological processes.
A Combined Algorithm for Optimization: Application for Optimization of the Transition Gas-Liquid in Stirred Tank Bioreactors10-18
Mitko Petrov
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A combined algorithm for static optimization is developed. The algorithm includes a method for random search of optimal an initial point and a method based on fuzzy sets theory, combined in order to be found for the best solution of the optimization problem. The application of the combined algorithm eliminates the main disadvantage of the used fuzzy optimization method, namely decreases the number of discrete values of control variables. In this way, the algorithm allows problems with larger scale to be solved. The combined algorithm is used for optimization of gas-liquid transition in dependence on some constructive and regime parameters of a laboratory scale stirred tank bioreactor. After the application of developed optimization algorithm significant increase of mass-transfer effectiveness, aeration and mixing processes in the bioreactor are observed.
Genetic Algorithms for a Parameter Estimation of a Fermentation Process Model: A Comparison19-28
Olympia Roeva
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In this paper the problem of a parameter estimation using genetic algorithms is examined. A case study considering the estimation of 6 parameters of a nonlinear dynamic model of E. coli fermentation is presented as a test problem. The parameter estimation problem is stated as a nonlinear programming problem subject to nonlinear differential-algebraic constraints. This problem is known to be frequently ill-conditioned and multimodal. Thus, traditional (gradient-based) local optimization methods fail to arrive satisfied solutions. To overcome their limitations, the use of different genetic algorithms as stochastic global optimization methods is explored. These algorithms are proved to be very suitable for the optimization of highly non-linear problems with many variables. Genetic algorithms can guarantee global optimality and robustness. These facts make them advantageous in use for parameter identification of fermentation models. A comparison between simple, modified and multi-population genetic algorithms is presented. The best result is obtained using the modified genetic algorithm. The considered algorithms converged very closely to the cost value but the modified algorithm is in times faster than other two.
Control of Biotechnological Systems
Using of Dynamic and Rollout Neuro - Dynamic Programming for Static and Dynamic Optimization of a Fed-batch Fermentation Process29-35
Tatiana Ilkova
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A fed-batch fermentation process is examined in this paper for experimental and further dynamic optimization. The static optimization is developed for to be found out the optimal initial concentrations of the basic biochemical variables – biomass, substrate and substrate in the feeding solution. For the static optimization of the process the method of Dynamic programming is used. After that these initial values are used for the dynamic optimization carried out by a submethod of Neuro-dynamic programming-rollout. The general advantage of this method is that the number of the iterations in the cost approximation part is decreased.
Bioprocess Systems
Studies of the Saccharomyces cerevisiae Cultivation under Oscillatory Mixing Conditions36-42
Andrējs Bērziņš, Uldis Viesturs, Māris Rikmanis, Stoyan Tzonkov
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Saccharomyces cerevisiae was cultivated under non-aerated conditions in a 5 l laboratory bioreactor. Using the experimental data and the regression analysis method, some mathematical correlations for stirrer rotational speed oscillation frequency and the reaction of the yeast were established. It has been found that different growth parameters are influenced variously by stirrer rotational speed and stirrer rotational speed oscillation frequency. Stirring oscillations can be among the methods for stimulation of biotechnological processes. The obtained results can be used for designing bioreactors and optimizing working conditions.
Biologically Inspired Object Localization for a Modular Mobile Robotic System43-56
Zlatogor Minchev
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The paper considers a general model of real biological creatures’ antennae, which is practically implemented and tested, over a real element of a mobile modular robotic system - the robot MR1. The last could be utilized in solving of the most classical problem in Robotics – Object Localization. The functionality of the represented sensor system is described in a new and original manner by utilizing the tool of Generalized Nets - a new likelihood for description, modelling and simulation of different objects from the Artificial Intelligence area including Robotics.
Biomedical Systems
Pharmacological Interventions for Prevention of Cardiovascular Disease in Type 2 Diabetes (T2DM): A Review of Some Meta-analytic Comparisons57-62
Anthony Shannon, Ching Wong
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The purpose of the studies reported here was to examine the effects of pharmacological interventions in the prevention or reduction of the risk of cardiovascular disease in Type 2 diabetes mellitus (T2DM). The original studies were from the results of meta-analyses of experimental data. This paper reviews these studies in order to comment on apparent anomalies among their results.
Hospital-acquired and Community-acquired Uropathogens; Modelling of Infection63-67
Aija Žileviča
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Urinary tract infections are among the most common human infections. They may be community-acquired or nosocomial, and caused by a variety of microorganisms. In the present study, we analysed more than 4000 urine samples collected from in-patients and outpatients, and registered the differences in the etiological spectrum of agents. The most widespread uropathogens are gram-negative rods, from them E. coli, Klebsiella spp. and the non-fermentive genus Pseudomonas. Women are more intensively affected by E. coli. From gram-positive cocci, the leading agents are coagulase negative Staphylococci, followed by S. aureus. No differences were registered between the genders. Polyresistance among gram-negative uropathogens is high.
Analysis and Optimization of Medical Ultrasound Imaging Using the Effective Aperture Approach68-81
Milen Nikolov, Vera Behar
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An effective aperture approach is used as a tool for analysis and parameter optimization of mostly known ultrasound imaging systems - phased array systems, compounding systems and synthetic aperture imaging systems. Both characteristics of an imaging system , the effective aperture function and the corresponding two-way radiation pattern, provide information about two the most important parameters of images produced by an ultrasound system - lateral resolution and contrast. Therefore, in the design, optimization of the effective aperture function leads to optimal choice of such parameters of an imaging systems that influence on lateral resolution and contrast of images produced by this imaging system. The numerical results show that Hamming apodization gives the best compromise between the contrast of images and the lateral resolution produced by a conventional phased array imaging system. In compound imaging, the number of transducers and its spatial separation should be chosen in result of optimization of the effective aperture function of a system. It is shown that the effective aperture approach can be also used for optimization of a sparse synthetic transmit aperture (STA) imaging system. A new two-stage algorithm is proposed for optimization of both the positions of the transmit elements and the weights of the receive elements. The proposed system employs a 64- element array with only four active elements used during transmit.
Fast Algorithm for Vectorcardiogram and Interbeat Intervals Analysis: Application for Premature Ventricular Contractions Classification82-93
Irena Jekova, Vessela Krasteva
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In this study we investigated the adequacy of two non-orthogonal ECG leads from Holter recordings to provide reliable vectorcardiogram (VCG) parameters. The VCG loop was constructed using the QRS samples in a fixed-size window around the fiducial point. We developed an algorithm for fast approximation of the VCG loop, estimation of its area and calculation of relative VCG characteristics, which are expected to be minimally dependent on the patient individuality and the ECG recording conditions. Moreover, in order to obtain independent from the heart rate temporal QRS characteristics, we introduced a parameter for estimation of the differences of the interbeat RR intervals. The statistical assessment of the proposed VCG and RR interval parameters showed distinguishing distributions for N and PVC beats. The reliability for PVC detection of the extracted parameter set was estimated independently with two classification methods - a stepwise discriminant analysis and a decision-tree-like classification algorithm, using the publicly available MIT-BIH arrhythmia database. The accuracy achieved with the stepwise discriminant analysis presented sensitivity of 91% and specificity of 95.6%, while the decision-tree-like technique assured sensitivity of 93.3% and specificity of 94.6%. We suggested possibilities for accuracy improvement with adequate electrodes placement of the Holter leads, supplementary analysis of the type of the predominant beats in the reference VCG matrix and smaller step for VCG loop approximation.

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