A dual method for parameter identification under deterministicuncertainty

Proposes a numerical method for reduction of a priori bounds on the values of uncertain plant parameters. The method successively eliminates parts of the parameter domain which are inconsistent with the plant measurement. The size of the eliminated parts is determined by a measure of inconsistency evaluated with the help of the support functions of the set of feasible states and of the set of possible measurements. We specify our approach on an identification problem for a linear control system with bounds on the magnitude and/or on the energy for the disturbances in the dynamics and in the measurement     

Spectroscopic investigation of tantalum nitride thin film deposition by reactive sputtering in a triode system

In the present paper the change of the partial pressure of nitrogen during reactive dc triode sputtering of a Ta target in Ar+N₂ gas mixture is spectroscopically investigated by means of a quadrupole mass spectrometer. AES analysis of thin films, deposited at different N₂ partial pressures is carried out and the atomic concentration of the contaminants in the films is investigated. It is established that the change of nitrogen content in the sputtering gas and in the deposited films at different N₂ partial pressures is connected with a nitridation of the Ta target.     

A new approach to Lipschitz continuity in state constrained optimal control

For a linear-quadratic state constrained optimal control problem, it is proved in [11] that under an independence condition for the active constraints, the optimal control is Lipschitz continuous. We now give a new proof of this result based on an analysis of the Euler discretization given in [9]. There we exploit the Lipschitz continuity of the control to estimate the error in the Euler discretization. Here we show that the theory developed for the Euler discretization can be used to derive the Lipschitz continuity of the optimal control.     

Experimental investigation into strengthened short reinforced concrete corbels by bonding carbon fiber fabrics

This paper presents the mechanical behavior of strengthened short reinforced concrete corbel bonded by composite carbon fiber fabrics. Often, short reinforced concrete corbel is used in Civil Engineering and in building constructions. In fact, this paper investigated the influence of some parameters on the mechanical behavior of corbel specimens. The parameters are the carbon fiber fabric layers, type of strengthening by gluing directly fabrics on the front and rear of specimen faces or by wrapping. The composite materials used in this study are unidirectional and bidirectional carbon fiber fabrics. The ultimate load is obtained from monotone static test. The extensometer technique based on gauge strain is used to study the local behavior of structures. This technique allows one to measure strains of electric gauges glued to the surface of carbon fiber fabrics, concrete and steel bar. Finally, the cracking and failure modes of specimen are presented.     

Error estimates for discretized differential inclusions

We present an estimate for the Hausdorff distance between the set of solutions of a differential inclusion and the set of solutions of its Euler discrete approximation, using an averaged modulus of continuity for multifunctions. A computational procedure to obtain a certain solution of the discretized inclusion is proposed.     

Relaxation and well-posedness of nonlinear optimal processes

An optimal control problem with perturbed nonlinear dynamics and perturbed state constraints is considered. The equivalence between performance well-posedness and regularity in the sense of relaxation is studied.     

Implementing the water framework directive in Bulgaria: Integrated river basin management on the Black Sea coast.

EC member states and candidate countries are in the process of implementing the requirements of the EC Water Framework Directive 2000/60, which came into force on 22 December 2000. At the core of the Directive is an integrated approach for sustainable water management in river basin districts. The overall objective is to reach good water status for all waters by the year 2015. The challenges for countries implementing the Directive are substantial not least for the River Basin Management Authorities who will be the implementing unit at the regional level. The Black Sea River Basin Directorate in Varna is one of four Directorates established in Bulgaria in 2002 in accordance with the Bulgarian Water Act and is the regional operational unit under the Ministry of Environment and Water for the Black Sea Basin catchment area. The catchment area covers 20% of Bulgaria and 100% of the Bulgarian Black Sea coast. Current implementation activities in the Black Sea Basin Directorate and also at the national level are supported by the Danish EPA through its DANCEE programme in collaboration with the Ministry of Environment and Water. This paper highlights the main activities and outputs of the technical and institutional undertakings in the Black Sea Basin Directorate focusing on the preparation of the River Basin Overview by Dec. 2004.     

Lipschitz properties of the attainable set of singularly perturbed linear systems

We consider a linear control system containing a small positive parameter η in a part of the derivatives. It is shown that for every ε (0,1) the map: η → attainable set, is Lipschitz continuous with exponent .     

A new approach to Lipschitz continuity in state constrained optimal control

For a linear-quadratic state constrained optimal control problem, it is proved in [11] that under an independence condition for the active constraints, the optimal control is Lipschitz continuous. We now give a new proof of this result based on an analysis of the Euler discretization given in [9]. There we exploit the Lipschitz continuity of the control to estimate the error in the Euler discretization. Here we show that the theory developed for the Euler discretization can be used to derive the Lipschitz continuity of the optimal control.     

Time-scale decomposition of the reachable set of constrained linear systems

We consider a linear control system with a multiparameter singular perturbation representing multiple time scales and with constraints for the control and the slow state. The Hausdorff limit of the reachable set when the small parameters tend to zero is found. The result provides a basis for a time-scale approximation of the reachable set.on leave from the Institute of Mathematics, Bulgarian Academy of Sciences, Sofia, Bulgaria.