Wyniki wyszukiwania - BazTech

1

Stability and positivity with respect to part of the variables for positive Markovian jump systems

Socha L.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2019

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Vol. 67, nr 4

769--775

EN

The stability and positivity of linear positive Markovian jump systems with respect to part of the variables is considered. The method-ologies of stability of positive systems with known transition probabilities based on common linear copositive Lyapunov function and stability of linear systems with respect to part of the variables are combined to find sufficient conditions of the stochastic stability and positivity of Markovian jump systems with respect to part of the variables. The results are extended for a class of nonlinear positive Markovian jump systems with respect to part of the variables. An example is given to illustrate the obtained results.

2

The Influence of Parameters of Argon Purging Process Through Ladle on the Phenomena Occuring in the Area of Phase Distributions: Liquid Steal-Slag

Pieprzyca J., Merder T., Saternus M., Gryc K., Socha L.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 2

653--658

EN

Purging the liquid steel with inert gases is a commonly used treatment in secondary metallurgy. The main purposes for which this method is used are: homogenization of liquid steel in the entire volume of the ladle, improvement of mixing conditions, acceleration of the absorption process of alloy additives and refining of liquid steel from non-metallic inclusions. The basic processing parameters of this treatment are: gas flow rate and the level of gas dispersion in liquid steel. The level of gas dispersion depends on the design and location of the porous plug in the ladle. Therefore, these parameters have a significant impact on the phenomena occurring in the contact zone of liquid steel with slag. Their improper selection may cause secondary contamination of the bath with exogenous inclusions from the slag, or air atmosphere due to discontinuity of the slag and exposure of the excessive surface of the liquid steel free surface. The article presents the results of modelling research of the effect of liquid steel purging with inert gases on phenomena occurring in this zone. The research was carried out using the physical (water) model of steel ladle. As a modelling liquid representing slag, paraffin oil was used, taking into account the conditions of similarity with particular reference to the kinematic viscosity. The results of the conducted research were presented in the form of visualization of phenomena occurring on the surface of the model liquid free surface in the form of photographs. The work is a part of a bigger study concerning modelling of ladle processes.

3

Physical Modelling of Degassing Process by Blowing of Inert Gas

Michalek K., Tkadlečková M., Socha L., Gryc K., Saternus M., Pieprzyca J., Merder T.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

987--992

EN

This paper deals with the possibilities of using physical modelling to study the degassing of metal melt during its treatment in the refining ladle. The method of inert gas blowing, so-called refining gas, presents the most common operational technology for the elimination of impurities from molten metal, e.g. for decreasing or removing the hydrogen content from liquid aluminium. This refining process presents the system of gas-liquid and its efficiency depends on the creation of fine bubbles with a high interphase surface, uniform distribution, long period of its effect in the melt, and mostly on the uniform arrangement of bubbles into the whole volume of the refining ladle. Physical modelling represents the basic method of modelling and it makes it possible to obtain information about the course of refining processes. On the basis of obtained results, it is possible to predict the behaviour of the real system during different changes in the process. The experimental part focuses on the evaluation of methodical laboratory experiments aimed at the proposal and testing of the developed methods of degassing during physical modelling. The results obtained on the basis of laboratory experiments realized on the specific physical model were discussed.

4

Research and Development of the Solidification of Slab Ingots from Special Tool Steels

Tkadlečková M., Michalek K., Gryc K., Socha L., Jonšta P., Saternus M., Pieprzyca J., Merder T.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1453--1458

EN

The paper describes the research and development of casting and solidification of slab ingots from special tool steels by means of numerical modelling using the finite element method. The pre-processing, processing and post-processing phases of numerical modelling are outlined. Also, problems with determining the thermophysical properties of materials and heat transfer between the individual parts of the casting system are discussed. Based on the type of grade of tool steel, the risk of final porosity is predicted. The results allowed to improve the production technology of slab ingots, and also to verify the ratio, the chamfer and the external/ internal shape of the wall of the new designed slab ingots.

5

Physical Modelling of Tundish Slag Entrainment under Various Technological Conditions

Michalek K., Gryc K., Socha L., Tkadlečková M., Saternus M., Pieprzyca J., Merder T., Pindor L.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1467--1471

EN

This paper deals with the issue of physical modelling of vortexes creation and tundish slag entrainment over the mouth of the nozzle into the individual casting strands. Proper physical model is equivalent to the operational continuous casting machine No. 2 in TŘINECKÉ ŽELEZÁRNY, a.s. Physical modelling methodology and simulated operational conditions are shortly described. Physical modelling was used for the evaluation of current conditions of steel casting at the application of different impact pads in the tundish. Further, laboratory measurement on the physical model aiming the determination of exact critical periods of vortexes creation and study of the slag entrainment as a consequence of changes in surface level during the tundish refilling to standard level were realised. The obtained results were analysed and discussed.

6

Study of Tundish Slag Entrainment Using Physical Modelling

Michalek K., Gryc K., Socha L., Saternus M., Tkadlečková M., Pieprzyca J., Merder T., Pindor L.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 1

257--260

EN

This paper deals with the possibilities of using physical modelling to study the slag entrainment in the tundish. A level of steel in the tundish is changing during sequential continuous casting. The most significant decrease in the steel level occurs when replacing ladles. It is generally known that if the height of steel level in the tundish drops below a certain critical level, it may generate vortexes over the nozzles and as a consequence entrainment of tundish slag into individual casting strands can occur. Thus, it is necessary to identify the critical level of steel for specific operational conditions. In this paper, the development of physical modelling methodology is described as well as physical model corresponding to operational continuous casting machine No. 2 in Třinecké železárny, a.s. The obtained results are discussed.

7

Study of Solidification of Continuously Cast Steel Round Billets Using Numerical Modellin

Tkadleckova M., Válek L., Socha L., Saternus M., Pieprzyca J., Merder T., Michalek K., Kováč M.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 1

221--226

EN

The paper is dedicated to the verification of solidification of continuously cast round steel billets using numerical modelling based on the finite element method. The aim of numerical modelling is to optimize the production of continuously cast steel billets of round format. The paper describes the pre-processing, processing and post-processing phases of numerical modelling. Also, the problems with determination of the thermodynamic properties of materials and the heat transfer between the individual parts of the casting system, including the definition of the heat losses along the casting strand in the primary and secondary cooling, were discussed. The first results of numerical simulation show the so-called thermal steady state of continuous casting. The temperature field, the metallurgical length and the thickness of the shell at the end of the mould were predicted. The further research will be concentrated on the prediction the risk of the cracks and the porosity based on the different boundary conditions.

8

Study of Casting and Solidification of Slab Ingot from Tool Steel Using Numerical Modelling

Tkadlečková M., Michalek K., Machovčák P., Kováč M., Socha L.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2879--2886

EN

The main problem in the production of forgings from tool steels, especially thick plates, blocks, pulleys and rods which are used for special machine components for demanding applications, it is the inhomogeneous structure with segregations, cracks in segregations or complex type of non-metallic inclusions MnS and TiCN. These forgings are actually produced from conventional forging ingots. Due to the size of forgings, it would be interesting the production of these forgings from slab ingots. It is possible that the production of forgings from slab ingots (which are distinguished by a characteristic aspect ratio A/B), it would reduce the occurrence of segregations. The paper presents the verification of the production process of slab steel ingots in particular by means of numerical modelling using finite element method. The paper describes the pre-processing, processing and post-processing phases of numerical modelling. The attention was focused on the prediction of behavior of hot metal during the mold filling, on the verification of the final porosity, of the final segregation and on the prediction of risk of cracks depending on the actual geometry of the mold.

PL

Głównym problemem w produkcji odkuwek ze stali narzędziowych, szczególnie grubych płyt, bloków, kół pasowych i prętów, używanych do specjalnych elementów maszyn dla żądanych zastosowań, jest niejednorodna struktura z segregacją, pęknięciami w segregacji lub złożonego typu niemetaliczne wtrącenia MnS i TiCN. Te odkuwki są rzeczywiście produkowane z konwencjonalnych wlewków przeznaczonych do kucia. Ze względu na wielkość odkuwek, można by produkować te odkuwki z wlewków płaskich. Możliwe, że produkcja odkuwki z wlewków płaskich (które wyróżniają się charakterystycznym stosunkiem A/B), pozwoli zmniejszyć występowanie segregacji. W pracy przedstawiono weryfikację procesu produkcji wlewków płaskich za pomocą modelowania numerycznego z wykorzystaniem metody elementów skończonych. Artykuł opisuje fazy modelowania numerycznego: wstępną fazę przetwarzania, obróbkę i przetwarzanie końcowe. Zwrócono uwagę na zachowanie się ciekłego metalu podczas napełniania wlewnic, na weryfikację końcowej porowatości, końcowej segregacji i przewidywania ryzyka pęknięcia w zależności od rzeczywistej geometrii wlewnic.

9

Influence of Direct Thermal Analysis Experimental Conditions on Determination of the High Temperature Phase Transformation Temperatures

Gryc K., Strouhalová M., Smetana B., Socha L., Michalek K.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2867--2872

EN

Thermo-physical and thermodynamic properties of metallic systems represent some of the most important data that allows to describe their behaviour under strictly specified conditions. These data are the basic, input data for simulative programs, which can model this behaviour and they can be applied to real conditions. Method of direct thermal analysis is the one of the methods of enabling to obtain such data. This paper deals with application of this method on particular sample of pure standard material. The experimental laboratory system for thermal analysis Netzsch STA 449 F3 Jupiter was used for experimental measurements. This paper is studying the influence of experimental conditions on the obtained temperature of phase transformations and on shift of phase transformation temperatures with respect to the monitored experimental conditions, accuracy and credibility of the measured data. Acquired values of this data could be significantly influenced by experimental conditions, size (mass) of samples, purity of inert atmosphere and also by regimes of controlled heating and cooling rates.

PL

Właściwości fizyczne i termodynamiczne układów metalicznych stanowią jedne z najważniejszych danych, które pozwalają opisać ich zachowanie w ściśle określonych warunkach. Dane te są podstawowymi danymi wejściowymi dla programu, który może symulować model tych zachowań i które mogą być zastosowane do rzeczywistych warunków. Metoda prostej (bezpośredniej) analizy termicznej jest jedną z metod pozwalających na uzyskanie takich danych. Niniejszy artykuł dotyczy zastosowania tej metody, w szczególności próbki czystego materiału standardowego. Do pomiarów eksperymentalnych było używane urządzenie dla analizy termicznej Netzsch STA 449 F3 Jupiter. W artykule analizowano wpływ warunków doświadczalnych na uzyskane temperatury przemian fazowych oraz na zmiany temperatur przemian fazowych z uwzględnieniem monitorowanych warunków doświadczalnych, dokładności i wiarygodności danych pomiarowych. Warunki doświadczalne, wielkości (masa) próbek, czystość atmosfery obojętnej, a przedziały kontrolowanej szybkości ogrzewania i chłodzenia mogą w znaczący sposób wpływać na otrzymane wartości tych danych.

10

Evaluation of Influence of Briquetted Synthetic Slags on Slag Regime and Process of Steel Desulphurization

Socha L., Michalek K., Bažan J., Gryc K., Machovčák P., Opler A., Styrnal P.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 2

809--813

EN

This paper presents the industrial results of evaluation of efficiency of synthetic slags during the treatment of steel at the equipment of the secondary metallurgy under conditions of the steel plant VÍTKOVICE HEAVY MACHINERY a.s. The aim of the heats was to assess the influence of the briquetted and sintered synthetic slags based on AI2O3 aiming the course of the steel desulphurization and slag regime during the production and treatment of steel grade 42CrMo4 with the technology EAF→LF→ VD. Within the plant experiments, basic parameters influencing the steel desulphurization and slag regime were monitored: desulphurization degree, basicity, content of easily reducible oxides, proportion of CaO/AI2O3 and Mannesmann’s index. Obtained results allowed to compare the steel desulphurization and to evaluate the slag regime. It was proved that the synthetic slag presenting the briquetted mixture of secondary corundum raw materials can adequately replace the synthetic slag created from the sintered mixture of natural raw materials.

PL

W pracy tej przedstawiono przemysłowe wyniki oceny efektywności zastosowania żużli syntetycznych podczas obróbki pozapiecowej stali w zakładzie VÍTKOVlCE HEAVY MACHINERY a.s. Celem badań był a ocena wpływu brykietówanych i spiekanych żużli syntetycznych opartych na AI2O3 - na przebieg odsiarczania stali i żużla podczas produkcji i obróbki stali 42CrMo4. zgodnie z technologią EAF → LF → VD. Podczas eksperymentów w zakładzie, monitorowano podstawowe parametry wpływające na odsiarczania stali i żużla: stopień odsiarczania, zasadowość, zawartość tlenków łatwo redukowałnych, stosunek CaO/AI2O3 oraz indeks Mannesniann’a. Uzyskane wyniki pozwoliły na porównanie stopnia odsiarczania stali w kontekście zastosowanych żużli. Wykazano, że syntetyczny żużel składający się z brykietowanej mieszaniny wtórnego korundu, może zastąpić syntetyczny żużel otrzymywany ze spieku mieszaniny surowców naturalnych.

11

The effect of boundary conditions of casting on the size of porosity of heavy steel ingot

Tkadlečková M., Michalek K., Gryc K., Smetana B., Machovčák P., Socha L.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 56, nr 1

29--37

EN

Purpose: The paper presents new knowledge from numerical modelling of porosity in heavy steel ingot using ProCAST software. The main aim of numerical modelling realized under the conditions of the Department of Metallurgy and Foundry and Regional Materials Science and Technology Centre at the VSB-TU Ostrava is the optimization of the production of heavy steel ingots produced at the companyVítkovice Heavy Machinery a.s. Design/methodology/approach: The selected method of numerical modelling enables 3D fully dimensional numerical simulation of steel casting and the subsequent solidification of steel with the possibility of prediction of ingot defects. Findings: The numerical modelling of casting and solidification of the 90 ton heavy steel ingot under different boundary conditions of the casting led to these main conclusions: In all simulated variants, the final character of solidification was very similar. The lowest level of porosities were achieved in the variant when we used the longer filling time together with decrease of casting temperatures. However, the tested adjustment of casting technology appeared to have only small impact on the resulting porosity. Practical implications: The change of geometry of the mould will have probably more effect on the character of the solidification than only the small changes of the casting parameters which are dependent on the steel grade. Originality/value: On the basis of applied research in close collaboration with industry companies, the obtained data can contribute significantly to optimization the operating conditions, thereby increasing the efficiency of the steelmaking technology and final quality of cast steel.

12

Study of Fe-C-based alloys by dynamic methods of thermal analysis

Gryc K., Smetana B., Žaludová M, Tkadlečková M., Michalek K., Socha L., Klus P., Dobrovská J., Machovčák P.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 55, nr 2

694--699

EN

Purpose: of this paper is to determine the temperatures of liquidus/solidus temperatures for multicomponent Fe-C-based alloys (industrially produced steel grades). The obtained results could be used in settings of conditions of steel casting and/or in the numerical simulations of processes occurring during casting and solidification of steel. Design/methodology/approach: Two modern apparatus for dynamic thermal analysis were used. Measurements of liquidus/solidus temperatures were realized by two thermal analysis methods. Experiments by the differential scanning calorimetry were done using the new one Setaram Multi High Temperature Calorimeter with 3D sensor (smaller samples about 2.6 g). The direct thermal analysis was used for large samples (23 g) at the STA 449 F3 Jupiter equipment. Findings: The differences between calculated and experimentally obtained values of liquidus/solidus temperatures were found. Also temperatures of solidification process are different than for “equilibrium” conditions. Practical implications: Presented results will be implemented into steel production practice - lowering of superheating of steel during ingot casting. The obtained temperatures will be implemented also into numerical simulations of ingot solidification. Originality/value: Two thermal analysis methods with different sample mass of steel was used under conditions of one research team. The direct cooperation between steel plant experts and university research team was applied. The utilization of results is the next phases of cooperated research of the authors.

13

Utilization of thermal analysis to thermo physical properties study of real steel grades

Klus P., Zaludova M, Gryc K., Smetana B., Michalek K., Dobrovska J., Tkadleckova M., Socha L.

Archives of Materials Science and Engineering

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2012

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Vol. 58, nr 2

116--119

EN

Purpose: This paper deals with determining the temperatures of phase transformations in real steel grades. It also includes the study of industrially produced steel grades using the methods of thermal analysis by experimental equipment STA 449 F3 Jupiter made by NETZSCH and Setsys 18TM made by SETARAM. Design/methodology/approach: Selected methods of thermal analysis (DSC and DTA) enable to obtain the temperatures of phase transformations taking place in steel during the linear heating/cooling. Within the casting technology of steel, thermal analysis is used to determine the solidus temperature and especially the crucial liquidus temperature. Findings: Experimentally obtained solidus and liquidus temperatures are higher in the DSC method (max. 3.8°C). The difference between the temperatures of phase transformation (T) running between the solidus temperature (TS) and liquidus (TL) for both methods (DTA and DSC) differ by a maximum of 3.2°C. The results from experimental measurements were compared with theoretical calculations of liquidus and solidus temperatures by different authors and with the computed results from thermodynamic database COMPUTHERM and also with temperatures from the equilibrium phase diagram of Fe-Cr-C. Experimentally obtained solidus temperatures are lower than the calculated equilibrium solidus temperatures. Experimentally obtained liquidus temperatures are in the range of temperatures obtained using computational relations. The temperatures mentioned in the equilibrium phase diagram (diagram for a particular steel grades was not found) are higher than experimentally obtained temperatures. Research limitations/implications: The results of experimental studies can be used to refine the knowledge of basic physical properties of steel and for example replacement of the tabulated values or estimated values of phase transformation temperatures and thermal capacity. Furthermore, the obtained data will be implemented in the material databases of numerical programs used for the simulation of metallurgical processes. Originality/value: On the basis of applied research in close collaboration with industry companies, the obtained data can contribute significantly to optimize the operating conditions, thereby increasing the efficiency of the steelmaking technology and final quality of cast steel.

14

Evaluation of slag regime in ladle during utilization of briquetted synthetic slag in VHM a.s.

Socha L., Bazan J., Gryc K., Machovcak P., Opler A., Trefil A., Melecky J.

Archives of Materials Science and Engineering

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2012

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Vol. 57, nr 2

80--87

EN

Purpose: The paper focuses on evaluation of slag regime by the help of synthetic slags based on Al2O3. The comparion of influence of synthetic slags on the production of two chosen grades of steels focused on evaluation of effectivity of created refining slag during treatment in the secondary metallurgy was the objective of plant experiments. Design/methodology/approach:During evaluation of slag regime in the ladle, steel samples for assessment of desulphurization degree were taken under the plant conditions. Slag samples were also taken for evaluation of chosen parameters: basicity, content of easily reducible oxides, proportion of CaO/Al2O3 and Mannesmann’s index. The temperature and oxygen activity in steel was continuously measured too. Findings: From plant experiments, it was found out that during using of two different types of synthetic slags during production of steel grades St52-3 and S34MnV similar values of desulphurization degree were achieved. Chosen parameters of ladle slag were monitored and it was demonstrated that the developed synthetic slag B reaches the results comparable with the standard used synthetic slag A. Research limitations/implications: Plant experiments were made under conditions of VÍTKOVICE HEAVY MACHINERY a.s. plant Obtained results are limited by the testing during production of two different steel grades St52-3, S34MnV and by the specific technology of production formed by EAF→LF→VD/VCD. Practical implications: The research results made it possible to realize the optimalization of slag regime under the plant conditions of VÍTKOVICE HEAVY MACHINERY a.s. plant. It was proved that developed synthetic slag B from the company JAP TRADING s.r.o. can adequately replace the common synthetic slag A. Originality/value:Results mentioned in this paper are intended for steel producers and they represent basic information about possibilities of slag regime optimalization in the ladle.

15

Lie algebra approach in the study of the stability of stochastic linear hybrid systems

Seroka E., Socha L.

Journal of Theoretical and Applied Mechanics

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2011

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Vol. 49 nr 1

31-50

EN

The problem of the stability of a class of stochastic linear hybrid systems with a special structure of matrices and a multiplicative excitation is considered. Sufficient conditions of the exponential p-th mean stability and the almost sure stability for a class of stochastic linear hybrid systems with the Markovian switching are derived. Also, sufficient conditions of the exponential mean-square stability for a class of stochastic linear hybrid systems satisfying the Lie algebra conditions with any switching are found. The obtained results are illustrated by examples and simulations.

PL

W pracy rozważony został problem stabilności klasy liniowych stochastycznych układów hybrydowych ze szczególną strukturą macierzy i multiplikatywnym szumem. Znalezione zostały warunki wystarczające dla eksponencjalnej p-średniej stabilności i eksponencjalnej stabilności prawie na pewno dla klasy stochastycznych liniowych układów hybrydowych z Markowskim przełączaniem. Dodatkowo podane zostały warunki wystarczające dla eksponencjalnej stabilności średnio-kwadratowej dla klasy stochastycznych liniowych układów hybrydowych z dowolnym przełączaniem spełniających warunki Lie algebry. Otrzymane wyniki zilustrowane zostały przykładami i symulacjami.

16

Modification of Slag in the Ladle by the Help of Briquetted Fluxing Agents

Socha L., Bazan J., Gryc K., Styrnal P., Pilka V., Piegza Z.

Hutnik, Wiadomości Hutnicze

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2011

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Vol. 78, nr 9

772--774

EN

The paper presents results of influence of thinner additions into the steelmaking slag on steel desulphurization in the ladle. Comparison of effectivity of two developed briquetted thinners based on Al2O3 with the thinner in common used at the steelworks Třinecké železárny, a.s. was made.

PL

W artykule przedstawiono wyniki badań wpływu dodatków upłynniacza żużla na odsiarczanie stali w kadzi stalowniczej. Przeprowadzono porównanie skuteczności dwóch rodzajów badanego, brykietowanego upłynniacza żużla na bazie Al2O3 z upłynniaczem powszechnie stosowanym w stalowni Třinecké železárny, a.s.

17

Recycling of steel and foundry fly ash in electric arc furnaces and cupola furnaces

Socha L., Bazan J., Styrnal P.

Hutnik, Wiadomości Hutnicze

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2010

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Vol. 77, nr 9

485-487

EN

Production of steel and cast iron in metallurgical units generates fly ashes. These fly ashes represent dangerous waste, which is not recycled in metallurgical plants and which is only dumped to disposal sites. This procedure is financially highly disadvantageous for producers. One of possibilities of partial processing consists in retrogressive recycling in charge of primary metallurgical units. The paper presents some operational results of compressed fly ashes from steelmaking plants and foundries. Operation tests were realised for verification of behaviour and efficiency of processing. They were focused on behaviour of fly ashes in the course of production of steel and cast iron and on their influence on technological process. The obtained results were verified by comparison with results of heats, into which no fly ashes were added.

PL

W procesie produkcji stali i żeliwa w agregatach metalurgicznych powstają pyły unoszone wraz z gazami poreakcyjnymi. Te pyły stanowią niebezpieczny odpad, który nie jest w zakładach metalurgicznych recyklingowany lecz często jest tylko deponowany. Taka procedura jest dla producenta finansowo bardzo niewygodna. Jedną z możliwości częściowego przetwarzania jest powrotny recykling do wsadu podstawowych agregatów metalurgicznych. Przedstawiono niektóre wyniki recyklingu prasowanych pyłów stalowniczych i odlewniczych. W celu sprawdzenia możliwości wykorzystania tych pyłów przeprowadzono badania, które miały na celu wyjaśnienie zachowania się pyłu przy produkcji stali i żeliwa oraz ich wpływ na proces technologiczny. Wyniki uzyskane w tych badaniach były porównane z wynikami wytopów, przy których pyły do wsadu nie były dodawane.

18

Corrosion tests of refractory materials

Socha L., Horakova D., Bazan J., Hasek P.

Prace Instytutu Metalurgii Żelaza

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2006

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T. 58, nr 4

7-9

EN

The paper is devoted to corrosion tests of various types of refractory materials at the interface with liquid steel and slag. Two evaluation procedures were created for the corrosion test, which consist of various experimental methods - for example: visual evaluation, microanalysis of structure, X-rays phase analysis and fluorescence spectrometry. The first type of corrosion test is aimed on tundish nozzle, which was put to the test in the steel. The second type of corrosion test is aimed on lining in the pouring ladle, which was put to the test in the slag. From, the results it is evident which of the used methods are proper for the evaluation of refractory materials under different conditions.

PL

Niniejsza praca poświęcona jest badaniom korozyjnosci różnego typu materiałów ogniotrwałych na granicy faz pomiędzy stałą ciekłą i żużlem. Opracowano dwie procedury badań korozyjności, które obejmują różne metody doświadczalne - na przykład: ocenę wzrokową, mikroanalizę struktury, rentgenowską analizę fazową oraz spektrometrię fluorescencyjną. Pierwszy rodzaj badań korozyjnosci dotyczy wylewu kadzi pośredniej, który został poddany badaniom w stali. Drugi rodzaj prób korozyjnych służy do badania wyłożenia kadzi odlewniczej, które zostało poddane badaniom w żużlu. Na podstawie wyników stwierdzono, którą z zastosowanych metod należy zastosować do oceny materiałów ogniotrwałych w różnych warunkach.

19

Application of poli-criterial linearization for control problem of stochastic dynamic systems

Socha L.

Journal of Theoretical and Applied Mechanics

|

2005

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Vol. 43 nr 3

675--693

EN

The problem of the determination of response characteristics and quasi-optimal control for nonlinear stochastic dynamic systems by using a multi-criteria linearization technique is presented in this paper. This idea was first introduced in previous author's paper (Socha, 1999a) for a simple dynamic system. In this paper, it is extended, and detailed analysis is given for a nonlinear oscillator with Gaussian external excitations and for a few criteria of statistical linearization. The obtained results are illustrated by a numerical example for Duffing's oscillator.

PL

W pracy przedstawiono problem wyznaczania quasi-optymalnego sterowania w nieliniowych stochastycznych układach dynamicznych za pomocą wielokryterialnej metody linearyzacji stochastycznej. Pomysł wielokryterialnej linearyzacji został zasygnalizowany we wcześniejszej pracy autora (Socha, 1999a). W niniejszym artykule jest on rozwinięty i zastosowany do problemu sterowania, a szczegółowa analiza jest przeprowadzona dla nieliniowego oscylatora z addytywnym wymuszeniem Gaussa.

20

A comparison of statistical and equivalent linearization for stochastic dynamic systems

Socha L.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2001

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z. 15

323-328

EN

The objective of this paper is to show differences between statistical and equivalent linearization on an example of a nonlinear oscillator under Gaussian white noise external excitations and to establish assumptions under what conditions the both linearization techniques are the same. Two types of equivalency criteria are considered, namely mean-square criterion with Gaussian closure and square metric in probability density functions space.

PL

Celem niniejszego artykułu jest pokazanie różnic między statystyczną i równoważną linearyzacją na przykładzie oscylatora nieliniowego oraz ustalenie założeń, przy których obie metody są identyczne. Rozpatrywane będą dwa typy kryteriów: kryterium średnio-kwadratowe z Gaussowską techniką zamykania oraz kryterium kwadratowe w przestrzeni funkcji gęstości prawdopodobieństw.