Volume 15, number 2
Editorial
New books
Invited Paper
Multi-unit Integration in Microfluidic Processes: Current Status and Future Horizons77-84
Pratap R. Patnaik
[ +/- abstract ][ full text ]
Microfluidic processes, mainly for biological and chemical applications, have expanded rapidly in recent years. While the initial focus was on single units, principally microreactors, technological and economic considerations have caused a shift to integrated microchips in which a number of microdevices function coherently. These integrated devices have many advantages over conventional macro-scale processes. However, the small scale of operation, complexities in the underlying physics and chemistry, and differences in the time constants of the participating units, in the interactions among them and in the outputs of interest make it difficult to design and optimize integrated microprocesses. These aspects are discussed here, current research and applications are reviewed, and possible future directions are considered.
Bioprocess systems
Kalman Filter Design for a Second-order Model of Anaerobic Digestion85-100
Boyko Kalchev, Ivan Simeonov, Nicolai Christov
[ +/- abstract ][ full text ]
The paper deals with the state estimation of a second-order model of anaerobic digestion. This estimation is necessary to implement the sophisticated control algorithms that have already been developed for this process. Hereby design and performance of a classical Kalman filter (compared with other two deterministic estimation approaches) for the main variables of this model have been discussed and analysed by simulations. The performance analysis has been conducted at realistic random perturbations, comparable with experimental data, on the one hand, and on the other – with and without parameter perturbations. Although at random perturbations alone the Kalman filter has a clear advantage over the two equipollent deterministic estimators, at the presence also of parameter perturbations, to which the Kalman filter is more sensitive, no such advantage is guaranteed.
Genetic Algorithm Tuning of PID Controller in Smith Predictor for Glucose Concentration Control101-114
Tsonyo Slavov, Olympia Roeva
[ +/- abstract ][ full text ]
This paper focuses on design of a glucose concentration control system based on nonlinear model plant of E. coli MC4110 fed-batch cultivation process. Due to significant time delay in real time glucose concentration measurement, a correction is proposed in glucose concentration measurement and a Smith predictor (SP) control structure based on universal PID controller is designed. To reduce the influence of model error in SP structure the estimate of measured glucose concentration is used. For the aim an extended Kalman filter (EKF) is designed. To achieve good closed-loop system performance genetic algorithm (GA) based optimal controller tuning procedure is applied. A standard binary encoding GA is applied. The GA parameters and operators are specified for the considered here problem. As a result the optimal PID controller settings are obtained. The simulation experiments of the control systems based on SP with EKF and without EKF are performed. The results show that the control system based on SP with EKF has a better performance than the one without EKF. For a short time the controller sets the control variable and maintains it at the desired set point during the cultivation process. As a result, a high biomass concentration of 48.3 g·l-1 is obtained at the end of the process.
Biomedical systems
Technical Device for Prevention of Spinal Column Disorders. Pilot EMG Study for Estimation of Back Muscle Activity115-130
Rositza Raikova, Kristian Tahtakov, Vihren Chakarov
[ +/- abstract ][ full text ]
One possible cause of abnormal spinal column curvatures in adolescents is standing in “bad posture” for a long time. If this bad habit can be corrected on time, by creating a dynamic stereotype for correct body position maintenance, further health problems can be avoided. To present a technical device for prevention of scoliotic deformations signaling when the angles of inclination forward or sideward are bigger than preliminary set ones. To elaborate an experimental protocol based on analysis of EMG activity (EMGs) of spine muscles for verification of its effect. Study design: Devising of the device and of software for EMGs processing. Pilot experiments were conducted recording EMGs of eight spinal muscles for estimation of the device efficiency. Different mathematical procedures were proposed and programmed for data processing and illustration. Two device prototypes (with sound and vibration signal) are developed and experimentally used. EMG data from 20 motor tasks (half of them with carrying the device) are processed. The device can be used as a simple tool for biofeedback-type pupil teaching of dynamic stereotype for right posture maintenance. The developed software for EMGs processing can be used for tracing the effect of using the device.
Assisted Living Systems for Elderly and Disabled People: A Short Review131-139
Ivo Iliev, Ivan Dotsinsky
[ +/- abstract ][ full text ]
The number of elderly people living alone in their homes is permanently growing in the whole western world. Because of the deteriorating capabilities to sense and interact with the environment, such as memory, eye sight, hearing and mobility, the ageing populations often live with significantly degraded life quality. Many also suffer from chronic diseases that require medical treatment and periodical examinations. Different Assisted Living Systems have been proposed to cope with the problems. The goal is to enable the elderly people to live longer in their preferred environment, to enhance the quality of their live and to reduce the expenses of the public health care. The Assisted Living Systems are based on a lot of sensors, actuators and multimedia equipment, providing for the autonomy of people and assisting them in carrying out their daily activities together with available interaction with remote relatives and friends. The applied approaches and implementations are specific that limit the dissemination of the results between the object oriented groups. Besides, most of the projects require considerable funding for implementation. For the time being and especially for some countries with lower Gross Domestic Product, the efforts may be directed to creation of low-cost assistive systems performing some basic tasks, related to the need and health status of the living alone adults or disabled people, e.g. automatic fall detection and signalization, as well as instantaneous monitoring the photo-pletismographic signals together with permanently available communication interface between the caregiver and the user.

© 2011, BAS, Institute of Biophysics and Biomedical Engineering