Time filter

Source Type

Kowalewski A.,Academy of Mining and Metallurgy of Poland
European Control Conference, ECC 1999 - Conference Proceedings | Year: 2015

Various optimization problems associated with the optimal control of distributed parameter systems with retarded arguments appearing in the boundary conditions have been studied recently by [wang], [know], [wong], [kow88a], [kow88b], [kow93a], [kow93b], [kow98a], [kow98b], and [kowdud]. In this paper, we consider an optimal distributed control problem for a linear hyperbolic system in which retarded argument appears in the integral form in the Neumann boundary condition. The performance functional has the quadratic form. The time horizon is fixed. Finally, we impose some constraints on the distributed control. Necessary and sufficient conditions of optimality with the quadratic performance functional and constrained control are derived for the Neumann problem. © 1999 EUCA.

Barbacki A.P.,Academy of Mining and Metallurgy of Poland
Environment Protection Engineering | Year: 2010

The paper discusses the geological and technical aspects of geothermal energy utilization in south-east Poland, such as the availability of thermal aquifers and the techniques for putting the latter into practical use. The geological and geothermal features of the region are presented within the context of existent aquifers whose geothermal resources could be used for heating and recreation. Particulary favourable hydrogeological conditions exist in the Inner Carpathians, in the Podhale Trough, where one geothermal plant and thermal pools that exploit geothermal energy can be found. Equally interesting are the areas north of the Cracow-Tarnów-Rzeszów line, where in the Tertiary, Mesozoic and Paleozoic aquifers of the Miechów Trough and the Carpathian Foredeep a water temperature ranges from 20 to 60 °C (in Poland, thermal water is defined as a water with well-head temperature of above 20 °C). The paper presents technological solutions for the recovery and management of heat in this area, together with the examples of how heat pumps and combined heat and power units are used in Poland. In order to assess the geothermal potential of a given area, we must first determine whether the extraction of geothermal heat there is economically viable. To answer this question we must consider two basic elements, i.e. the type of thermal aquifer involved and the technological solutions that can be applied to utilize the source [1], [2].

Barbacki A.,Academy of Mining and Metallurgy of Poland
Renewable and Sustainable Energy Reviews | Year: 2012

Geothermal resources in Poland are of growing importance for the production of renewable energy. The total installed geothermal capacity (including heat pumps) at the end of 2008 was ca. 281 MWt, while heat sales about 1501 TJ. Poland is characterised by low-temperature geothermal resources connected mostly with the Mesozoic sedimentary formations. In the paper the estimation of thermodynamic potential of Polish geothermal fields in comparison with selected global resources was presented. Geothermal resources were classified with reference to their specific exergy and specific exergy index (SEI). These indices define the quality of the energy content of a geothermal fluid better than conventional temperature criterions. © 2011 Elsevier Ltd. All rights reserved.

Orlowska E.,IThemba LABS | Orlowska E.,University of Aarhus | Przybylowicz W.,IThemba LABS | Przybylowicz W.,Academy of Mining and Metallurgy of Poland | And 4 more authors.
Environmental Pollution | Year: 2011

The effect of arbuscular mycorrhizal fungi (AMF) on growth and element uptake by Ni-hyperaccumulating plant, Berkheya coddii, was studied. Plants were grown under laboratory conditions on ultramafic soil without or with the AM fungi of different origin. The AM colonization, especially with the indigenous strain, significantly enhanced plants growth and their survival. AMF affected also the elemental concentrations that were studied with Particle-induced X-ray emission (PIXE). AMF (i) increased K and Fe in shoots, Zn and Mn in roots, P and Ca both, in roots and shoots; (ii) decreased Mn in shoots, Co and Ni both, in shoots and roots. Due to higher biomass of mycorrhizal plants, total Ni content was up to 20 times higher in mycorrhizal plants compared to the non-mycorrhizal ones. The AMF enhancement of Ni uptake may therefore provide an improvement of a presently used technique of nickel phytomining. © 2011 Elsevier Ltd. All rights reserved.

Kuak A.,Academy of Mining and Metallurgy of Poland | Kuak A.,Jagiellonian University | Nieckarz Z.,Jagiellonian University | Zieba S.,Jagiellonian University
Journal of Geophysical Research: Atmospheres | Year: 2010

Measurements of extremely low frequency (ELF) transients can be used to obtain model parameters and rates of the strong cloud-to-ground (CG) lightning discharges that generate them. In this study, we present an analytical description of a CG lightning discharge which takes into account both a return stroke and a continuing current. Using quasi-TEM (q-TEM) solutions for the Earth-ionosphere waveguide for distances within the near zone we show that the ELF spectrum of transients strongly depends on the percentage contribution of the continuing current to the discharge process. It is supposed that during typical observational conditions the only parameter of an ELF transient that can be measured sufficiently accurately is the impulse amplitude. In relation to the observational conditions the consequences of the calibration of ELF receivers on the measured ELF impulse amplitude are discussed, particularly the role of antialias filters. It is demonstrated that measurements of the ELF transient amplitude at a known distance to the source allows the total dipole moment of the discharge to be calculated and allows contributions of the return stroke and continuing current to this process to be estimated. Furthermore, some techniques of the signal spectral filtration that enable independent measurements of the return and continuing phase of the discharge are discussed. Copyright 2010 by the American Geophysical Union.

Discover hidden collaborations