Autor: Kulesza, S. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: The Mechanism of Transformation of Global Business Cycles into Dynamics of Regional Real Estate Markets
Autorzy:: Jakimowicz, A.
Kulesza, S.
Powiązania:: https://bibliotekanauki.pl/articles/1029167.pdf
Data publikacji:: 2018-06
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: housing price dynamics
structural transition
cusp catastrophe
critical point
bifurcation set
equilibrium surface
Opis:: The aim of this article is the identification of the occurrence mechanism of sudden quantitative changes in real-estate market prices, which were observed during the global financial crisis. Since such phenomena did not occur to such an intensity during previous crises, it can be assumed that a new economic dynamic type has emerged in real-estate markets. The most promising of the methods of studying such phenomena seems to be the bifurcation method and particularly the catastrophe theory. This study analyzes changes in the prices of residential property based on cusp catastrophes. Empirical data were fit to a stochastic cusp model to visualize the evolutionary path of real estate market. Two other popular models (linear and logistic) were also estimated to compare results. A comparative analysis proved that the cusp model can best explain structural price instabilities in real-estate markets. The results confirmed that the evolution of the real estate market combines two processes: long-term evolution in the area of non-degenerate stability and discontinuous changes in the area of degenerate stability. Structural changes take place in the system only in the area of degenerate stability. The theoretical and practical results show that the catastrophe theory may have predictive potential, which could support traditional methods of predicting changes on real estate markets.
Źródło:: Acta Physica Polonica A; 2018, 133, 6; 1351-1361
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Real Estate Market under Catastrophic Change
Autorzy:: Bełej, M.
Kulesza, S.
Powiązania:: https://bibliotekanauki.pl/articles/1400163.pdf
Data publikacji:: 2013-03
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 05.45.-a
89.20.-a
89.65.Gh
Opis:: Within the last decade, real estate prices in Poland have changed significantly. We believe that these prices inevitably reflect the dynamics of the real estate market, and therefore they can be used to track its evolution path. To study whether and how the prices (regarded as a state variable) change over time depending on such control variables as gross domestic product and central bank interest rates, the theory of discontinuous change (also known as the catastrophe theory) was used. Catastrophic model assumes that small price fluctuations are associated with stable, long-term development of the market, whereas rapid changes are always due to short-term instabilities. In such a picture, the system evolution path draws a smooth curve within the stability area passing continuously between neighboring equilibrium states, and it rarely enters into the instability area to jump over the potential barrier to another equilibrium state.
Źródło:: Acta Physica Polonica A; 2013, 123, 3; 497-501
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Local Real Estate Markets in Poland as a Network of Damped Harmonic Oscillators
Autorzy:: Kulesza, S.
Belej, M.
Powiązania:: https://bibliotekanauki.pl/articles/1388528.pdf
Data publikacji:: 2015-03
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 05.70.Ln
89.65.Gh
89.75.Da
Opis:: The paper deals with time series of housing prices on local real estate markets in Warszawa (WAW), Kraków (KRK) and Poznań (POZ) from 2006 to 2013 using a model of critically-damped harmonic oscillator to study underlying system dynamics. Performed analysis reveals the presence of housing bubble in 2007 that emerge from otherwise quasi-regular evolution around the equilibrium state. Time series of housing prices are fitted numerically to estimate important parameters of the system, for example: decay constant, delay time, and price equilibrium level, which help us to chose the leading market. Obtained results show reasonable matching of the model with housing prices in WAW and POZ, but less in KRK. The latter data, however, are found to agree well with the model of under-damped harmonic oscillator, which actually suggests that some trembling might occur in that market. Nevertheless, local real estate markets can be thought of as a system of interconnected damped harmonic oscillators with leading market in WAW that is about to change under aggregate macroeconomic fluctuations (exogenous factors) triggering changes in remaining markets.
Źródło:: Acta Physica Polonica A; 2015, 127, 3A; A-99-A-102
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Characteristics of porous beds based on fractal parameters
Autorzy:: Bramowicz, M.
Kulesza, S.
Sobieski, W.
Powiązania:: https://bibliotekanauki.pl/articles/298066.pdf
Data publikacji:: 2017
Wydawca:: Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:: granular beds
porosity
fractal analysis
numerical modeling
Opis:: The paper presents the results of a fractal analysis of the cross-sections of a porous mineral deposit consisting of spherical elements which formed a spatial system with varying porosity (0.4 to 0.95). The virtual deposit was generated using the Discrete Element Method in the YADE code by means of the so-called Radius Expansion Method. The fractal analysis was carried out using the structure function method, determining the fractal dimension (D), the topothesy (L) and the corner frequency (l) (MAINSAH et al. 2001). The conducted simulations have confirmed to a considerable extent the test results available in the literature involving the fractal analysis of mineral deposits with varying porosity. They clearly indicate that the fractal dimension does not change along with the porosity of the deposit, if the autocorrelation function or their transformations (e.g. structure function) methods are used. Moreover, based on the information available in the literature, it can be concluded that the value of the fractal dimension corresponds to mineral deposits with the specified geometric shapes of the elements which form them.
Źródło:: Technical Sciences / University of Warmia and Mazury in Olsztyn; 2017, 20(2); 171-179
1505-4675
2083-4527
Pojawia się w:: Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: A Comparison between Contact and Tapping AFM Mode in Surface Morphology Studies
Autorzy:: Bramowicz, M.
Kulesza, S.
Rychlik, K.
Powiązania:: https://bibliotekanauki.pl/articles/298112.pdf
Data publikacji:: 2012
Wydawca:: Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:: mikroskopia sił atomowych
AFM
topografia powierzchni
atomic force microscopy (AFM)
surface topography
Opis:: The paper presents recent results from studies of a surface topography of a platinum calibration grid on silicon substrate obtained in both contact and tapping modes of the AFM microscope. The results are analyzed in order to determine the influence of the scan set-up and the SPM probe onto estimated fractal parameters and surface anisotropy ratio.
Źródło:: Technical Sciences / University of Warmia and Mazury in Olsztyn; 2012, 15(2); 307-318
1505-4675
2083-4527
Pojawia się w:: Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Changes in magnetic domain structure of maraging steel studied by magnetic force microscopy
Autorzy:: Bramowicz, M.
Kulesza, S.
Mrozek, G.
Powiązania:: https://bibliotekanauki.pl/articles/298122.pdf
Data publikacji:: 2014
Wydawca:: Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:: maraging steel
magnetic force microscopy
fractal analysis
Opis:: The paper presents results on whether and how the magnetic domain structure in maraging steel undergoes any change due to the aging process. It continues the works on application of correlation methods and fractal analysis into studies of magnetic properties of various steel alloys using Scanning Probe Microscopy. It is aimed at verifying the usefulness of the structure function for description of spatial changes in shape and orientation of magnetic domains, and the magnitude of magnetic stray field affected by the heat treatment. Obtained results suggest that despite vanishing magnetic tip-surface interaction, and hence vanishing magnetic stray field, magnetic domains remain nearly perfectly isotropic although randomly oriented. Similar to isotropic real surfaces, the fractal dimension of the magnetic domains turns out to be independent of the structural changes induced by the aging process, whereas the topothesy is found to vary within order of magnitude along with changes in the magnetic stray field. After all, obtained results lead to conclusion that the aging process leaves its fingerprints in the structure of the steel alloys, which can be studied using numerical analysis of images of magnetic interactions between vibrating tip and the stray field.
Źródło:: Technical Sciences / University of Warmia and Mazury in Olsztyn; 2014, 17(4); 371-379
1505-4675
2083-4527
Pojawia się w:: Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: FPGA Based Active Magnetic Bearings Controller
Autorzy:: Kulesza, Z. S.
Powiązania:: https://bibliotekanauki.pl/articles/387274.pdf
Data publikacji:: 2011
Wydawca:: Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:: sterownik
łożysko magnetyczne
controller
magnetic bearing
Opis:: The article discusses main problems of implementing the PID control law in the FPGA integrated circuit. Consecutive steps of discretizing and choosing the fixed-point representation of the continuous, floating-point PID algorithm are described. The FPGA controller is going to be used in the active hetero-polar magnetic bearings system consisting of two radial and one axial bearings. The results of the experimental tests of the controller are presented. The dynamic performance of the controller is better when compared with the dSPACE controller, that was used so far. The designed hardware and software, the developed implementation procedure and the experience acquired during this stage of the whole project are going to be used during the implementation of more sophisticated control laws (e.g. robust) in the FPGA for AMB controllers.
Źródło:: Acta Mechanica et Automatica; 2011, 5, 2; 59-64
1898-4088
2300-5319
Pojawia się w:: Acta Mechanica et Automatica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Rotor Crack Detection Approach Using Controlled Shaft Deflection
Autorzy:: Kulesza, Z. S.
Powiązania:: https://bibliotekanauki.pl/articles/386800.pdf
Data publikacji:: 2012
Wydawca:: Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:: dynamika
diagnostyka
wirnik
pęknięcie
rotor dynamics
shaft crack
strucutre health monitoring
Opis:: Rotating shafts are important and responsible components of many machines, such as power generation plants, aircraft engines, machine tool spindles, etc. A transverse shaft crack can occur due to cyclic loading, creep, stress corrosion, and other mechanisms to which rotating machines are subjected. If not detected early, the developing shaft crack can lead to a serious machine damage resulting in a catastrophic accident. The article presents a new method for shaft crack detection. The method utilizes the coupling mechanism between the bending and torsional vibrations of the cracked, non/rotating shaft. By applying an external lateral force of a constant amplitude, a small shaft deflection is induced. Simultaneously, a harmonic torque is applied to the shaft inducing its torsional vibrations. By changing the angular position of the lateral force application, the position of the deflection also changes opening or closing of the crack. This chang/ es the way the bending and torsional vibrations are being coupled. By studying the coupled lateral vibration response for each angular position of the lateral force one can assess the possible presence of the crack. The approach is demonstrated with a numerical finite element model of a rotor. The results of the numerical analysis demonstrate the potential of the suggested approach for effective shaft crack detection.
Źródło:: Acta Mechanica et Automatica; 2012, 6, 4; 32-40
1898-4088
2300-5319
Pojawia się w:: Acta Mechanica et Automatica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Application of the Autocorrelation Function and Fractal Geometry Methods for Analysis of MFM Images
Zastosowanie funkcji autokorelacji oraz geometrii fraktalnej do analizy obrazów struktur domenowych rejestrowanych metodą MFM
Autorzy:: Bramowicz, M.
Kulesza, S.
Czaja, P.
Maziarz, W.
Powiązania:: https://bibliotekanauki.pl/articles/352007.pdf
Data publikacji:: 2014
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: atomic force microscopy (AFM)
magnetic force microscopy
magnetic domains
fractal analysis
mikroskopia sił magnetycznych
MFM
analiza fraktalna
Opis:: Presented work is focused on the use of correlation methods for numerical analysis of magnetic stray field over the surface of materials. Obtained results extend our previous findings about application of the autocorrelation function and the fractal analysis for characterization of magnetic surfaces. Several domain images are recorded at various tip-sample gaps (i.e. the lift heights), and then their average widths were extrapolated down to the zero distance in order to estimate the width seen right on the surface. Apart from that, fractal parameters were derived from autocorrelation function, which turned out to be sensitive to the lift height, and might constitute universal measure (the critical lift height), above which the MFM signal became dominated by thermal noises and non-magnetic residual interactions.
Niniejsza praca dotyczy zastosowania metod korelacyjnych do numerycznej analizy obrazów rozkładu pola magnetycznego emitowanego z obszarów spontanicznego namagnesowania. W pracy przedstawiono kontynuację badań nad zastosowaniem funkcji autokorelacji oraz metod analizy fraktalnej w badaniach struktury domenowej oraz charakterystyki emitowanego z nich pola magnetycznego. Wyniki badań wykazują zależność mierzonej metodami mikroskopii sił magnetycznych (MFM) szerokości domen od wysokości skanowania nad badaną powierzchnią, sugerując przeprowadzanie serii pomiarów na różnych wysokościach (h), ich aproksymację z następną ekstrapolacją do powierzchni (h=0). Przeprowadzona analiza fraktalna, wskazuje na możliwość jej aplikacji do charakterystyki zmian sygnału magnetycznego rejestrowanego przez MFM. Pozwala ona również na wyznaczenie wysokości krytycznej (hkr), na której sygnałem dominującym stają się nakładające się na sygnał magnetyczny pozostałości niemagnetycznych interakcji między igłą sondy i badaną powierzchnią, stanowiące rejestrowany przez MFM szum.
Źródło:: Archives of Metallurgy and Materials; 2014, 59, 2; 451-457
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Structural studies of welds in wear-resistant steels
Autorzy:: Bramowicz, M.
Kulesza, S.
Lewalski, P.
Szatkowski, J.
Powiązania:: https://bibliotekanauki.pl/articles/1112878.pdf
Data publikacji:: 2016-10
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 81.20.Vj
81.05.Bx
Opis:: The work presents results of the research on changes in microstructural, and mechanical properties of the structural XAR 400 wear-resistant steel caused by the welding procedure. Metallographic and microhardness studies revealed complex microstructure of the welds that turned out to vary with the distance from the weld axis: predominance of the acicular ferrite (ACF) structures in the weld itself, quasi-polygonal ferrite (QPF) crystals with precipitates of troostite (T) in the heat-affected zone, and the bainitic ferrite (BF) structures in the heat-partially-affected zone.
Źródło:: Acta Physica Polonica A; 2016, 130, 4; 963-965
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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