Management of contamination risks and identification of contamination sources

Some aspects of management of contamination risks based on monitoring contamination sources are under consideration. The case when direct measurements are impossible and the values of the contamination inputs should be estimated through observations of indirect indicators is studied. Standard mathematical models describing the diffusion of a contaminant in the form of partial differential equations of the parabolic type are used. A model-based technique for the reconstruction of the evolution of the intensities of point-concentrated contamination sources through observations of the concentration of the contaminant is presented. Results of numerical experiments are discussed

On the Exact Stabilization of an Uncertain Dynamics

The study is motivated by the problem of stabilizing the concentration of atmospheric carbon, which is widely discussed in the context of global warming nowadays. A key difficulty in the design of stabilization strategies is the uncertainty of the underlying physical model. In the present paper, a general problem setting is suggested and a relevant analytic framework elaborated. Analysis employs specific qualitative features of an uncertain dynamics, including automatic stabilization of the trajectories in the absence of input disturbances. An asymptotic version of Krosovskii's external shift control principle is developed and model-robust strategies stabilizing a state coordinate at a prescribed level are constructed

On Estimation of Forcing Functions in Parabolic Systems

The present paper is an outcome of a research carried out at the Dynamic Systems project and the project on Advanced Computer Applications in 1994/95. The research is motivated by a problem of reconstruction of time-varying intensities of pollution sources in a water reservoir via measuring pollutant concentrations in accessible domains. We start with convergent input estimation algorithms for a system described by a general parabolic equation. One of the algorithms is specified for a particular diffusion-type groundwater contamination model, and tested numerically

Classification of multidimensional element types in automatic regulation systems

This study examines the possibility of applying the A.A. Krasovsky method of complex coordinates and complex transfer functions for multidimensional element types modeling. As it is demonstrated, the method can be taken as the basis for multidimensional regulation system design along with the extended version of classification suggested by A.A. Krasovsky

Far-infrared electrodynamics of superconducting Nb: comparison of theory and experiment

Complex conductivity spectra of superconducting Nb are calculated from the first principles in the frequency region around the energy gap and compared to the experimental results. The row experimental data obtained on thin films can be precisely described by these calculations.Comment: 4 pages, 3 eps figures incl. Accepted to Solid State Commu

Comparison of spark channel expansion in hydrogen, oxygen and nitrogen

The results of the spark channel expansion simulation in various gases such as hydrogen, oxygen and nitrogen have been presented. Difference in thermodynamic properties of the various gases has been taken into account. Influence of a type of gas on the discharge current, the spark resistance, the energy deposited in the spark and the spark gas-dynamic expansion has been found out. Influence of initial species concentration in mixture of nitrogen, hydrogen and oxygen on detonation initiation by spark discharge has been discussed.Представлені результати моделювання розширення іскрового каналу в різних газах, таких як водень, кисень і азот. Враховано відмінність y термодинамічних властивостях різних газів. Виявлено вплив типу газу на розрядний струм, іскровий опір, енергію, вкладену в іскру, і газодинамічне розширення іскри. Обговорено вплив початкової концентрації частинок y суміші азоту, водню і кисню на ініціювання детонації іскровим розрядом.Представлены результаты моделирования расширения искрового канала в различных газах, таких как водород, кислород и азот. Учтено различие в термодинамических свойствах различных газов. Выявлено влияние типа газа на разрядный ток, искровое сопротивление, энергию, вложенную в искру, и газодинамическое расширение искры. Обсуждено влияние начальной концентрации частиц в смеси азота, водорода и кислорода на инициирование детонации искровым разрядом

Experimental evidence of two-band behavior of MgB2

The break-junction tunneling has been systematically investigated in MgB2. Two types of the break-junction contacts have been exploited on the same samples, which demonstrated tunnel contact like (SIS) and point contact like (SnS) behavior. Both of them have shown the existence of the two distinct energy gaps. We have observed also the peculiarities on the I(V)- characteristics related to Leggett's collective mode assisted tunneling. --> Corresponding author address: [email protected]: 14 pages, 6 figures, 1 table; corrected typos and fig