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MONITORING THE KINETICS OF BIOPROCESS VARIABLES – THEORY AND APPLICATIONS V. Lyubenova Key Words Model-based software sensors; biotechnological processes; kinetics estimation Abstract A new method for monitoring of bioprocess kinetics is developed where there exists a set of measured variables but the use of constant values of kinetic parameters is not acceptable. The method is based on new formalization of kinetics of biotechnological processes. It is generalized in one vector including unknown time-varying parameters only. For kinetics estimation, a general structure of software sensor is presented. A optimization procedure for tuning of the sensor’s parameters is proposed on the basis of stability and convergence analysis. The proposed method is applied for monitoring of bioprocesses for gluconic acid, alphaamylase and ethanol production Article PDF Download article (PDF)

PERTURBATION ANALYSIS OF THE LMI-BASED CONTINUOUS-TIME LINEAR QUADRATIC REGULATOR PROBLEM FOR DESCRIPTOR SYSTEMS A. Yonchev Key Words Continuous-time descriptor systems; perturbation analysis; linear quadratic regulator LMI based control problem. Abstract This paper considers an approach to perform perturbation analysis of linear quadratic regulator (LQR) control problem for continuous-time descriptor systems. The investigated control problem is based on solving LMIs (Linear Matrix Inequalities) and applying Lyapunov functions. The paper is concerned with obtaining linear perturbation bounds for the continuous-time LQR control problem for descriptor systems. The computed perturbation bounds can be used to study the effect of perturbations in system and controller on feasibility and performance of the considered control problem. A numerical example is also presented in the paper Article PDF Download article (PDF)

DIGITAL SIGNING OF DATA IN THE WEB-BASED INFORMATION SYSTEMS D. Pilev Key Words Information security; digital certificate; data authentication; digital signature Abstract Digital signing of data in the Web-based IS is one of the most secure methods for guaranteeing the authenticity of data. Storage of user keys is particularly important for this methodology. The present development proposes a new algorithm for storage and usage of user keys for the database by the digital certificate of the client. The proposed methodology was designed for protection of data in a particular information system. One of the characteristics of this system is the great number of authorized users with rights for access and modification of various parts of data. With such systems it is extremely important to guarantee the authenticity of data stored in the system. Digital signing of data provides such guarantee of their authenticity. Article PDF Download article (PDF)

MODEL ASPECTS OF QUALITY OF SERVICE MANAGEMENT IN MACHINE TO MACHINE COMMUNICATIONS I. Atanasov, A. Nikolov, E. Pencheva Key Words Device management; light-weight M2M; bisimulation; autonomous agent. Abstract Machine-to-Machine communications (M2M) allow connected devices to exchange data and perform actions without human intervention. Different M2M applications have different quality of service (QoS) requirements. The dynamic QoS control is critical for applications like video surveillance, transportation services, and industrial control. The provided QoS depends on device connectivity. Connectivity management provides centralized management of M2M devices and connections. The paper studies model aspects of QoS management for connected M2M devices by means of connectivity management. Models for connectivity management are suggested, formally described and verified. The capabilities for device connectivity management are used to model the behavior of autonomous agent for dynamic QoS control. Article PDF Download article (PDF)

DESIGN AND IMPLEMENTATION OF CASCADE LQR CONTROLLER FOR STABILIZATION OF TWO-WHEELED ROBOT Ts. Slavov, J. Kralev, P. Petkov Key Words Two-wheeled robot control; LQR control; embedded systems. Abstract In this paper the developed two-wheeled robot and cascade LQR controller, Kalman filters, PI and PID controllers are presented. The cascade LQR controller stabilizes the two-wheeled robot in upright position. The PID controller ensures good tracking of wheel position reference and the PI controller steers twowheeled robot rotation around the vertical axis. A software in MATLAB®/Simulink environment intended for design and generation of control code which is embedded in a Texas Instruments Digital Signal Controller is developed. Simulation and experimental results of system performance are given that confirm the efficiency of the control system developed. Article PDF Download article (PDF)