Optimal deterministic observer design for linear continuous-time systems with unknown output disturbances in a ball in L2

The problem of the existence and design of an optimal observer for linear systems with unknown disturbances additive to the output is considered. The disturbances are assumed to be arbitrary L² functions constrained to a ball in L². The problem of reconstructing the best estimate of the state with respect to the worst disturbances is reformulated in terms of finding an operator L²-Rⁿ Satisfying some linear equalities and of minimal norm. The necessary and sufficient condition for the existence of such an operator is proved to be the well-known observability condition. The optimal observer is in the form of an integral operator. An explicit formula for its integrand is given. In addition, differential equations fulfilled by the optimal state estimate for the cases of a fixed or time-variable observation interval are derived.     

eVEREst—SUPPORTING ESTIMATION OF REAL ESTATE VALUE

Enhanced Value Estimation of Real Estates (eVEREst) is the project carried out at the Department of Management Information Systems at the Poznań University of Economics. The paper presents the idea and the architecture of a system that supports the real estate registry with additional information that enables more precise estimation of real estate value.     

1/ ƒ noise in binary random mixtures

Novel numerical results for a two-component random resistor network as a model of a mixture with non-zero conductivity of the insulating phase are presented. They confirm that the values of noise-critical exponent depend on the noise intensity of the components of the mixture     

MASS TRANSFER TO THE FREE INTERFACE IN STIRRED VESSELS

Liquid-phase mass transfer coefficients between gas and a flat liquid interface in a stirred tank are proportional to the average rate of energy dissipation raised to the power of one third for water and one quarter for organic solvents. This discrepancy can be attributed to the presence of surface active contaminants in aqueous systems. The critical value of the Reynolds number for the transition between the regime controlled by the small scale turbulence to that controlled by large scale eddies is about 100. The Levich-Davies model was found inappropriate in this case.     

Analogue-to-digital armature current transducer for chopper-fed DC motor drives

A transducer scheme is suggested, permitting A/D conversion of the armature current for microcomputer-controlled variable-frequency-chopper-fed DC motor drives. The transducer supplies the information about the average between two thyristor triggerings value of the armature current, independent of the frequency of the current.     

In situ resistance measurements as a method of polycondensation investigation in carbon-filled polyesterimide films

The resistance changes measured in the course of the curing process have been correlated with thermogravimetric investigation of the carbon/polyesterimide system (which is useful for the fabrication of polymer thick film resistors). This method of polycondensation process analysis permits us to control the manufacture of the resistors     

Random pulse-width modulation technique for voltage-controlled power inverters

As an alternative to the existing deterministic pulse-width modulation methods, a random pulse-width modulation technique for voltage-controlled power inverters is proposed. Advantages of the technique include non-repetitiveness of the switching pattern, simplicity of the hardware, and uncommonly high limits of switching frequency. A prototype random pulse-width modulator is described and experimental results are presented.     

MINE VENTILATION EXPERT SYSTEM

A growing trend in the area of artificial intelligence is the development of software that simulates the decision-making process of human experts. The purpose of this paper is to advance the use of available tools from the area of artificial intelligence, and in particular expert systems, into the field of mine ventilation management. The authors have developed an expert system (i.e., a smart manager) that controls the operation of a mine ventilation network. The expert system is rule based and hence can be (independently) enhanced in an incremental fashion. It serves as a smart interface between the monitoring and control components of a mine ventilation system.     

Robust stabilization of uncertain systems by periodic feedback

An uncertain control system described by a family parametrized by an unknown parameter that takes values in a known constraint set is considered. The robust stabilization problem is defined as finding a dynamic output controller that globally stabilizes the uncertain system; that is, no matter what the parameter value chosen by ‘Nature’, the closed-loop system is globally asymptotically stable. It is shown that in the class of dynamic periodic controllers the solution to this problem exists under reasonable assumptions given for a general family of abstract non-linear models. Those assumptions, in the case of a family of linear finite-dimensional models, are equivalent to suitable stabilizability and detectability assumptions. For this case, insensitivity of the design with respect to small errors in the data is proved.