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Tytuł:
Thermodynamic Interpretation of Pressure-Induced Spin Transitions in Thiosemicarbazonates of Iron(III)
Autorzy:
Krupska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399168.pdf
Data publikacji:
2013-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.-a
82.60.-s
Opis:
The thermodynamic interpretation of the spin transition in iron(II) complexes taking into consideration cooperative domains is given in the literature. We use a similar interpretation for thiosemicarbazonates of aromatic aldehydes of iron(III) compounds. We extend the spin transition interpretation to pressure-induced spin transitions. The relationship between a domain size n and the interaction between a high spin and a low spin states Γp given by Gütlich et al. allows us to deduce a modified equation of the spin transition pressure $p_{c}$ (at the temperature $T=T_{c}$). On the basis of this equation, the content of the fraction of the high spin state γ and of the fraction of the low-spin state, 1-γ, as a function of pressure can be theoretically estimated. The derived equation enables us to predict the width of hysteresis which refers to the high spin and low spin states formed under the high pressure as a result of the spin transition.
Źródło:
Acta Physica Polonica A; 2013, 124, 4; 626-628
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamics of the Exactly Solvable Spin-Electron Tetrahedral Chain
Autorzy:
Gálisová, L.
Powiązania:
https://bibliotekanauki.pl/articles/1402558.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.-a
75.10.Pq
Opis:
An exactly solvable spin-electron tetrahedral chain, where the Ising spins localized at nodal lattice sites regularly alternate with three equivalent lattice sites available for one mobile electron is considered. The system with ferromagnetic interaction between the Ising spins and electrons exhibits an enhanced magnetocaloric effect in the limit H/|J| → 0 when the entropy is very small, whereas the system with antiferromagnetic interaction between the Ising spins and electrons exhibits an enhanced magnetocaloric effect around the field H/J=1 when the entropy is sufficiently close to the value S/2N = ln[(1+√5)/2]. We study the thermodynamics of the system in these field regions.
Źródło:
Acta Physica Polonica A; 2015, 128, 2; 156-158
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on thermodynamic properties of Fe³⁺-substituted yttrium iron garnets
Autorzy:
Modi, K.
Jha, P.
Raval, P.
Vasoya, N.
Vyas, K.
Meshiya, U.
Gohil, R.
Jadav, K.
Gohil, N.
Sharma, P.
Powiązania:
https://bibliotekanauki.pl/articles/1158494.pdf
Data publikacji:
2016-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
05.70.-a
Opis:
This paper presents the molar heat capacity at constant volume C_{V} and characteristic Debye temperature θ, determination for the garnet system, Y_{3-x}Fe_{5+x}O_{12}, x=0.0, 0.1, 0.3, and 0.5 at 300 K. The θ values determined from Waldron's approach and those calculated using ultrasonic mean sound velocity, V_{mo}, are in agreement. C_{V} values calculated from the Einstein theory are consistent with the reported one and theoretically expected values using the Dulong-Petit law, but Waldron's approach based on the Debye theory and the Debye T³ law fail to estimate consistent C_{V} values. The result has been discussed in the light of key physical differences between the two theories. The applicability of the Kieffer model for molar heat capacity at constant pressure, C_{p}, determination has been tested. Finally, an attempt has been made to estimate electronic contribution and the temperature at which the lattice contribution and electronic contribution to the molar heat capacity become comparable.
Źródło:
Acta Physica Polonica A; 2016, 130, 3; 778-784
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Endoreversible Modeling and Optimization of a Multistage Heat Engine System with a Generalized Heat Transfer Law via Hamilton-Jacobi-Bellman Equations and Dynamic Programming
Autorzy:
Xia, S.
Chen, L.
Sun, F.
Powiązania:
https://bibliotekanauki.pl/articles/1504513.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.-a
05.60.Cd
05.70.Ln
Opis:
A multistage endoreversible Carnot heat engine system operating between a finite thermal capacity high-temperature fluid reservoir and an infinite thermal capacity low-temperature environment with a generalized heat transfer law [q ∝ ( Δ $(T^{n}))^{m}$] is investigated in this paper. Optimal control theory is applied to derive the continuous Hamilton-Jacobi-Bellman equations, which determine the optimal fluid temperature configurations for maximum power output under the conditions of fixed initial time and fixed initial temperature of the driving fluid. Based on the general optimization results, the analytical solution for the case with Newtonian heat transfer law [q ∝ Δ(T)] is further obtained. Since there are no analytical solutions for the other heat transfer laws, the continuous Hamilton-Jacobi-Bellman equations are discretized and the dynamic programming algorithm is adopted to obtain the complete numerical solutions of the optimization problem, and the relationships among the maximum power output of the system, the process period and the fluid temperature are discussed in detail. The results show that the optimal high-temperature fluid reservoir temperature for the maximum power output of the multistage heat engine system with Newtonian and linear phenomenological [q ∝ Δ $(T^{-1})$] heat transfer laws decrease exponentially and linearly with time, respectively, while those with the Dulong-Petit [q∝$(Δ T)^{1.25}$], radiative [q∝ Δ $(T^4)$] and [q∝$(Δ(T^4))^{1.25}$] heat transfer laws are different from the former two cases significantly.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 747-760
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymmetry Driven Phase Transformations
Autorzy:
Damczyk, J.
Ostasiewicz, K.
Radosiński, Ł.
Radosz, A.
Powiązania:
https://bibliotekanauki.pl/articles/1535592.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.-a
64.60.-i
63.70.+h
Opis:
Motivated by the properties of one-dimensional lattice systems with asymmetric on-site potential, one can formulate a hypothesis of an asymmetry driven phase transformation. Characteristic feature of one-dimensional systems exhibiting asymmetry driven phase transformation is a sequence of the two phase conversions. In particular class of such systems with a triple-well potential, phase conversions of one-dimensional systems would evolve into a sequence of two phase transitions in three-dimensional models. We propose here a model of three-dimensional system exhibiting a sequence of two first order asymmetry driven phase transitions.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 527-530
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In Quest of the Best Theoretical Description of Excess Molar Functions οf Binary Mixtures of Alcohols
Autorzy:
Geppert-Rybczyńska, M.
Hofman, T.
Powiązania:
https://bibliotekanauki.pl/articles/1811517.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.-a
05.70.Ce
82.60.Lf
Opis:
An attempt to describe excess molar functions of alkane + alcohol and alcohol + alcohol binary mixtures was made using the theoretical approach constructed on the basis of S-ERAS model and the chemical theory proposed by Campbell. The results obtained seem to be promising, however in order to complete the work, the procedure of determination of fitting parameters as well as relative magnitude of physical and chemical contributions to regarded excess molar quantities must be established.
Źródło:
Acta Physica Polonica A; 2008, 114, 6A; A-91-A-96
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance Prediction and Irreversibility Analysis of a Thermoelectric Refrigerator with Finned Heat Exchanger
Autorzy:
Meng, F.
Chen, L.
Sun, F.
Powiązania:
https://bibliotekanauki.pl/articles/1493399.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.-a
05.60.Cd
05.70.Ln
Opis:
A developed model of commercial thermoelectric refrigerators with finned heat exchanger is established by introducing finite time thermodynamics. A significant novelty is that physical properties, dimension parameters, temperature parameters and flow parameters are all taken into account in the model. Numerical studies and comparative investigation on the performance of a typical commercial water-cooling thermoelectric refrigerator which consists of 127 thermoelectric elements, are performed for cooling load and coefficient of performance. The results show that the maximum cooling load is 2.33 W and the maximum coefficient of performance is 0.54 when the cooling temperature difference is 10 K. Comparing the simulation results of several models, it is found that the heat convection of the heat exchanger and the heat leakage through the air gap are the main factors, which cause irreversibility and decrease the performance. Moreover, the performance can be improved by optimizing the length and cross-section area of thermoelectric elements. The model and calculation method may be applied to not only the analysis and performance prediction of practical thermoelectric refrigerators, but also the design and optimization of heat exchangers.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 397-406
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Irreversible Processes across Narrow Junctions
Autorzy:
Honig, J.
Hoehn, R.
Powiązania:
https://bibliotekanauki.pl/articles/1505330.pdf
Data publikacji:
2011-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.-a
05.70.Ln
44.10.+i
Opis:
The rectification of the second law of thermodynamics is used to directly relate irreversible heat and work transfers to reversible processes. This permits the construction of thermodynamic functions of state that include entropy contributions due to irreversible processes. A general expression is set up to determine the entropy changes in terms of experimentally accessible parameters when a system is interacting with its surroundings via quasistatic irreversible operations. The procedure is used to determine the entropy changes across a narrow junction in terms of pressure and temperature differences between the system and its surroundings, including cyclic processes.
Źródło:
Acta Physica Polonica A; 2011, 119, 3; 323-327
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the Molecular Shape on Its Thermodynamic Functions
Autorzy:
Lewandowska, A.
Konarski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813167.pdf
Data publikacji:
2008-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.20.-y
05.70.-a
33.10.Cs
Opis:
Free energy and entropy were calculated for molecules of different shapes in gas phase and under small pressure. The values of the thermodynamic functions were found strongly dependent on the molecular shape. The results obtained were applied to predict the route of internal energy deactivation as well as the preferred form of the molecules examined.
Źródło:
Acta Physica Polonica A; 2008, 113, 4; 1111-1115
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Semi-Empirical Modelling of Glass Forming Ranges for Y-Co-Si System
Autorzy:
Śniadecki, Z.
Narojczyk, J.
Idzikowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1366620.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.-a
61.43.Dq
81.30.Bx
Opis:
Glass forming abilities of a ternary Y-Co-Si system were determined on the basis of combined semi-empirical Miedema's and geometric models. The enthalpy of amorphous and solid solution phases formation, along with the mismatch entropy and GFA parameter, were analysed to indicate compositions with the highest ability for the amorphization. The large atomic radii difference between constituents, especially Y and Si, is the deciding factor of GFA. Compositions ranged between $Y_{33}Si_{67}$ and $Y_{45}Si_{55}$ are the best glass formers.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 62-63
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Study of the Frustrated Ising Antiferromagnet on the Honeycomb Lattice
Autorzy:
Bobák, A.
Lučivjanský, T.
Žukovič, M.
Borovský, M.
Balcerzak, T.
Powiązania:
https://bibliotekanauki.pl/articles/1032632.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
05.70.-a
75.10.Hk
Opis:
We study effects of the next-next-nearest-neighbour antiferromagnetic (J₃ < 0) interaction on critical properties (or phase diagram) of the frustrated spin-½ J₁-J₂-J₃ Ising antiferromagnet on the honeycomb lattice by using the effective-field theory with correlations. Beside the ground-state energy, we find that there is a region of J₃ < 0 in which the frustrated honeycomb lattice antiferromagnet exhibits a tricritical point, at which the phase transition changes from the second order to the first one on the line between Néel antiferromagnetic and paramagnetic phases.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 636-638
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tsallis Entropies of Superposition States οf Two Photon-Subtracted SU(1,1) Coherent States and Entanglement Transfer to Qubits
Autorzy:
Liang, Mai-Lin
Yuan, Bing
Zhang, Jia-Nan
Powiązania:
https://bibliotekanauki.pl/articles/1584983.pdf
Data publikacji:
2009-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.50.Dv
03.65.Ud
05.70.-a
Opis:
Entropy properties of the superposed photon-subtracted two-mode coherent states are quite different from that of the single state. Tsallis entropies of the superposed states have extreme values, while that of the single state change monotonously. Further, it is found that the positions of the maxima of the entropies are independent of the entropic index. Around the maxima of the entropies, the entanglement transfer from the superposed states to two initially separable qubits is nearly complete.
Źródło:
Acta Physica Polonica A; 2009, 116, 6; 1006-1010
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Elastic Properties and Phase Transitions in Some Alkali Halides Using Interatomic Potential Model
Autorzy:
Yazar, H. R.
Powiązania:
https://bibliotekanauki.pl/articles/2046838.pdf
Data publikacji:
2006-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Fv
05.70.-a
61.50.Ks
64.10.+h
Opis:
We have predicted the phase transition pressure in some alkali halides using an interatomic potential approach based on rigid ion model. This potential form represents the composite form of the inverse power dependence and exponential dependence of the repulsive energy on interionic distance. Some thermoelastic properties such as second order elastic constants have been calculated using the same potential. The phase transition pressures (28.69 and 2.4 GPa) obtained by us for two alkali halides (NaCl and KCl) are in closer agreement with their corresponding experimental data (29.0 and 2.0 GPa). This approach is promising with respect to prediction of the phase transition pressure of other alkali halides as well.
Źródło:
Acta Physica Polonica A; 2006, 109, 6; 743-751
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optoacoustic Measurements for Small-Volume Liquid Samples
Autorzy:
Egerev, S.
Powiązania:
https://bibliotekanauki.pl/articles/1377936.pdf
Data publikacji:
2015-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.35.Bf
43.35.Sx
05.70.-a
42.40.My
42.55.-f
Opis:
High sensitivity of optoacoustic measurement method makes it possible to use it for the analysis of the liquid samples having microliter volume. The core of any measurement optoacoustic system is represented by a so-called optoacoustic cell. The paper deals with a layered prism optoacoustic cell. It is well-suited for the small-volume sample analysis. In the paper, laser-induced elastic pulse in the layered prism cell is examined at the stage of its generation, at the stage of its propagation through the body of the cell, and at the stage of the wideband pick-up with the piezoelectric transducer. This pulse serves to determine trace concentrations of various impurities in the sample. The optimization of layered prism cell parameters is proposed. Figures of merit of optoacoustic determination of lipopolysaccharides in the liquid small-volume sample with the use of the optimized layered prism cell are evaluated as an example.
Źródło:
Acta Physica Polonica A; 2015, 127, 1; 10-14
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of a Mixed Hadronic-QGP System with Massive Particles
Autorzy:
Ghenam, L.
El Djoudi, A.
Powiązania:
https://bibliotekanauki.pl/articles/1402384.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
12.38.Mh
12.39.Ba
05.70.-a
05.70.Ce
05.70.Fh
64.10.+h
Opis:
We consider a mixed system of hadronic and quark-gluon plasma (QGP) phases in a finite volume, and use a phenomenological approach with two phases matter equations of state to study the occurring deconfinement phase transition with varying temperature and/or chemical potential. We take into account massive particles in both phases, and calculate several physical quantities describing well the system at the phase transition. We probe the behaviour of these quantities, by examining their variations with temperature and volume at fixed chemical potential, as well as with chemical potential and volume at fixed temperature, in three dimensional plots, and obtain the finite size effects on the deconfinement phase transition.
Źródło:
Acta Physica Polonica A; 2015, 128, 2B; B-341-B-343
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Models of Pedestrian Evacuation based on Cellular Automata
Autorzy:
Mrowinski, M.
Gradowski, T.
Kosinski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1409052.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
89.40.-a
45.70.Vn
05.50.+q
05.70.Fh
Opis:
We study two models of pedestrian evacuation based on cellular automata and intelligent agents. We use the static floor field approach and augment it with additional transition rules (random movement and preservation of personal space) in order to model various aspects of human behaviour. Through numerical simulations we investigate pedestrian evacuation from rooms with various geometries (e.g. empty room, classroom). Using heatmaps (density diagrams of pedestrians), average evacuation times, velocity and other parameters we study the effectiveness of evacuation and potential dangers pedestrians may encounter.
Źródło:
Acta Physica Polonica A; 2012, 121, 2B; B-95-B-100
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Olivine Particle Reinforced Polyphenylene Sulfide Matrix Composites
Autorzy:
Sahin, A.
Sinmazcelik, T.
Powiązania:
https://bibliotekanauki.pl/articles/1031954.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Qk
81.05.Zx
81.70.Bt
Opis:
Polyphenylene sulfide is a semicrystalline thermoplastic polymer. It offers an excellent balance of properties, including chemical resistance, high temperature resistance, dimensional stability, electrical characteristics and flowability. Polyphenylene sulfide must be filled with reinforced agents, such as fibers and fillers, to overcome its inherent brittleness. Because of its low viscosity, polyphenylene sulfide can be molded with high loading of fillers and reinforcements. These fillers and reinforcements will make a difference in the electrical properties, strength, dimensional stability, surface properties and overall cost. Because of its inherent flame retardancy, polyphenylene sulfide is ideal for high temperature electrical applications. On the other hand, olivine is volcanic based mineral with porous structure, which consists of forsterite (Mg₂SiO₄) and fayalite (Fe₂SiO₄). Both, its lower price compared to other minerals and harmlessness to human health increase the usage of olivine from day to day. For this reason olivine reinforced polyphenylene sulfide composite samples were manufactured at various weight ratios (0, 1, 3, 5 and 10 wt.%). Mechanical and scratch properties of samples were investigated and according to test results, it is concluded that olivine mineral can be used as a reinforcing agent material instead of other conventional fillers.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 481-483
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymmetry Coefficients as Indicators of Chaos
Autorzy:
Wąż, P.
Bielińska-Wąż, D.
Powiązania:
https://bibliotekanauki.pl/articles/1584980.pdf
Data publikacji:
2009-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.70.Rr
95.10.Fh
05.45.-a
05.45.Gg
05.45.Tp
Opis:
The aim of this paper is to present a new simple indicator of chaos derived from the dynamics of the motion. For this purpose statistical methods are used. A function describing the motion of the analyzed system (in the example under consideration, the time dependence of the angle of a damped driven pendulum, ω(t)) is recorded in time intervals t∊〈 $T_{s}$, $T_{f_{k}}$〉, k = 1, 2,...K, with $T_{f_{k}}$ > $T_{f_{k-1}}$. Each of the recorded functions is considered as a statistical distribution. The asymmetry coefficients of the set of distributions form a series and their behavior in periodic and chaotic regions is compared. It is shown that the behavior of this series in the chaotic and in the periodic regimes is entirely different. The changes of the asymmetry coefficients for the periodic cases are very regular and for the chaotic ones - random. In periodic cases, the coefficients converge to zero when the length of the distribution increases.
Źródło:
Acta Physica Polonica A; 2009, 116, 6; 987-991
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New type of composite gyrotropic metamaterial
Autorzy:
Paśko, W.
Zięba, P.
Tralle, I.
Çoruh, A.
Powiązania:
https://bibliotekanauki.pl/articles/1055044.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Xj
81.05.Zx
78.67.Pt
42.70.-a
Opis:
In this work we examined the possibility of fabricating the metamaterial in a relatively simple way. Our idea was to use the three-component mixture of ingredients, where one of them is responsible for the negative permeability μ(ω) of hypothetical metamaterial, while the other two cause the negative value of effective permittivity ε(ω). In our previous work, we considered Hg_{1-x}Cd_xTe semiconductor compound as one of the ingredients of mixture. As fabrication of the Hg_{1-x}Cd_xTe is related to using mercury which is very poisoning, we tried to exclude this material. In the work we proved by numerical simulations the possibility of substituting mercury cadmium telluride by Pb_{1-x}Sn_xTe. We have shown by computer simulations that by the proper fitting of the parameters, e.g. the radius of nanoparticles, their magnetic moments, the relative concentration of ingredients, etc., it is possible to obtain the metamaterial with negative refraction index in a relatively broad range of temperatures and magnetic fields. The last seems to be very promising in terms of practical applications of metamaterials.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 121-123
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fractals, Log-Periodicity and Financial Crashes
Autorzy:
Oświęcimka, P.
Drożdż, S.
Kwapień, J.
Górski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1538497.pdf
Data publikacji:
2010-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.35.Mw
05.45.Df
05.70.Jk
Opis:
Presence of self-similar patterns in the financial dynamics is by now well established and even convincingly quantified within the multifractal formalism. Here we focus attention on one particular aspect of this self-similarity which potentially is related to the discrete-scale invariance underlying the system composition and manifests itself by the log-periodic oscillations cascading self-similarly through various time scales. Such oscillations accumulate at the turning (critical) points that in the financial dynamics are often identified as crashes. This property thus allows us to develop a methodology that may be useful also for prediction. A model Weierstrass-type function is used to illustrate the relevant effects and several examples demonstrating that such effects in the real financial markets take place indeed, are reviewed.
Źródło:
Acta Physica Polonica A; 2010, 117, 4; 637-639
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Sound Attenuation and Spin-Lattice Relaxation
Autorzy:
Pawlak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1930585.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Jk
62.65.+k
Opis:
The nonasymptotic critical properties of sound propagation are studied in compressible magnetic system. The role of coupling of order parameter and acoustic phonons to spin-energy density is investigated and the ultrasonic attenuation scaling function is found.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 385-387
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymmetry Coefficients as Indicators of Chaos: Hyperchaotic Qi System
Autorzy:
Wąż, P.
Bielińska-Wąż, D.
Powiązania:
https://bibliotekanauki.pl/articles/1400122.pdf
Data publikacji:
2013-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.70.Rr
95.10.Fh
05.45.-a
05.45.Gg
05.45.Tp
Opis:
Statistical properties of the hyperchaotic Qi system are studied. The theory, recently formulated and applied for the damped driven pendulum, is used in this investigation. Asymmetry coefficients, related to the statistical moments of distributions composed from the time-series, are shown to behave in a different way for periodic, chaotic and hyperchaotic solutions and are proposed as indicators of chaos and hyperchaos.
Źródło:
Acta Physica Polonica A; 2013, 123, 4; 647-650
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Field Dependence of Critical Attenuation in Ferromagnet
Autorzy:
Pawlak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1427558.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Jk
62.65.+k
Opis:
The influence of magnetic field on the sound attenuation is investigated in ferromagnets. With the aid of the Nelson method we derive frequency-, magnetic field- and temperature-dependent expression for the sound attenuation coefficient near a critical point in the Ising-type system. The shift of the ultrasonic attenuation peak under the influence of magnetic field towards higher temperatures is discussed.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1185-1187
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Lattice Relaxation Effects in Critical Sound Propagation
Autorzy:
Pawlak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1964802.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.65.+k
05.70.Jk
Opis:
The nonasymptotic critical properties of sound propagation are studied in compressible Ising system above T$\text{}_{C}$. In the present paper we analyse a model where in addition to the coupling to two order-parameter fluctuations the sound mode couples linearly to the fluctuations of spin-energy and lattice-energy densities. Both subsystems exchange energy with the rate determined by the bare spin-lattice relaxation time. The total energy may be conserved or not. The crossover between insulator-like behaviour ~t$\text{}^{-2α}$ and metal-like behaviour ~t$\text{}^{-(zν+α)}$ in ultrasonic attenuation is investigated according to the value of ultrasonic frequency, the reduced temperature t, bare relaxation times and various coupling constants.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 449-452
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Complexes of Domain Walls in Ferromagnetic Stripes
Autorzy:
Janutka, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399260.pdf
Data publikacji:
2013-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.45.Yv
75.70.Kw
75.75.Jn
75.78.Fg
85.70.Kh
Opis:
Interaction of domain walls in ferromagnetic stripes is studied with relevance to the formation of stable complexes of many domains. Two domain wall system is described with the Landau-Lifshitz-Gilbert equation including regimes of narrow and wide stripes which correspond the presence of transverse and vortex domain walls. The domain walls of both kinds are characterized with their chiralities (the direction of the magnetization rotation in the stripe plane) and polarities (the magnetization orientation in the center of a vortex and/or halfvortices), hence, their interactions are analyzed with dependence on these properties. In particular, pairs of the domain walls of opposite or like chiralities and polarities are investigated as well as pairs of opposite (like) chiralities and of like (opposite) polarities. Conditions of the creation of stationary bubbles built of two interacting domain walls are formulated with relevance to the situations of presence and absence of the external magnetic field.
Źródło:
Acta Physica Polonica A; 2013, 124, 4; 641-648
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Sound Propagation in Magnetic Metals and Bottleneck Phenomena
Autorzy:
Pawlak, A.
Powiązania:
https://bibliotekanauki.pl/articles/2013730.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Jk
62.65.+k
Opis:
A semiphenomenological model of sound propagation in a critical magnetic system is proposed, which takes into account a relaxation of energy between the system of localised spins and the conduction electron spins as well as the coupling of the longitudinal phonon to bilinear combination of spin fluctuations and to the energy densities. A general expression for the acoustic self-energy is obtained within the one-loop approximation. The effect of "bottlenecking" and its influence on the critical singularities in the sound characteristics is discussed.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 909-912
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theory of Critical Sound Attenuation in Ising-Type Magnets
Autorzy:
Pawlak, A.
Powiązania:
https://bibliotekanauki.pl/articles/2014046.pdf
Data publikacji:
2000-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.65.+k
05.70.Jk
Opis:
The critical behaviour of sound attenuation has been studied in an elastically isotropic Ising system above the critical point on the basis of a complete stochastic model including both spin-energy and lattice-energy modes linearly coupled to the longitudinal sound mode. The effect of spin-lattice relaxation on the ultrasonic attenuation is investigated. The crossover between Kawasaki behaviour and Murata-Iro-Schwabl behaviour is studied as dependent on the values of ultrasonic frequency, reduced temperature, relaxation times, etc. A new high-frequency regime is discussed in the magnetic systems. This new regime corresponds to an adiabatic sound propagation and is very similar to the ones in binary mixture and liquid helium. A new frequency-dependent specific heat being the harmonic average of the bare lattice and critical spin specific heats is introduced. It was shown that such specific heat describes the process of equilibration between spin and lattice subsystems and includes the most important features of critical sound attenuation.
Źródło:
Acta Physica Polonica A; 2000, 98, 1-2; 23-39
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of Superhydrophilic Polyester Fabrics Using Various TiO₂ Colloidal Dispersions
Autorzy:
Ojstršek, A.
Kurečič, M.
Fakin, D.
Powiązania:
https://bibliotekanauki.pl/articles/1401222.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Lg
81.70.Fy
82.70.Dd
Opis:
The purpose of this research was to apply four stable colloidal dispersions, combining different TiO₂ core-shell nanoparticles, onto polyester fabric, according to exhaustion procedure, in order to enhance fabrics' water and moisture absorption properties. Firstly, all colloidal dispersions were analysed using transmission electron microscopy (TEM) and dynamic light scattering (DLS) and secondly, the morphologies of TiO₂ modified PES surfaces were evaluated by scanning electron microscopy (SEM). In addition, the superhydrophilic character of fibrous surfaces was investigated by water contact angle measurement. For this purpose, dynamic tensiometry was employed by measuring the changes in the net force on a surface during the repeated immersion and emersion of a solid into a probe liquid. The obtained results show excellent wettability of TiO₂ upgraded PES fabrics depending on the type of applied nano-sized TiO₂-hybride.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 953-956
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
External Noise Effects on the Electron Velocity Fluctuations in Semiconductors
Autorzy:
Persano Adorno, D.
Pizzolato, N.
Spagnolo, B.
Powiązania:
https://bibliotekanauki.pl/articles/1813387.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.70.+m
05.40.Ca
05.40.-a
Opis:
We investigate the modification of the intrinsic carrier noise spectral density induced in low-doped semiconductor materials by an external correlated noise source added to the driving high-frequency periodic electric field. A Monte Carlo approach is adopted to numerically solve the transport equation by considering all the possible scattering phenomena of the hot electrons in the medium. We show that the noise spectra are strongly affected by the intensity and the correlation time of the external random electric field. Moreover, this random field can cause a suppression of the total noise power.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 985-988
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Annihilation of o-Positronium in the Vicinity of the Critical Mixing Point
Autorzy:
Jerie, K.
Baranowski, A.
Gliński, J.
Orzechowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/2008045.pdf
Data publikacji:
1999-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Jk
78.70.Bj
Opis:
Positron annihilation spectra were investigated in the critical region close to the consolute point of ethanol + dodecane mixture. The anomalies of the positron lifetimes and intensities were small, nevertheless it was found that the intensity of short-living components of annihilation spectrum seems to increase close to the critical temperature.
Źródło:
Acta Physica Polonica A; 1999, 95, 4; 569-574
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance Analysis of a Dual Cycle Engine with Considerations of Pressure Ratio and Cut-Off Ratio
Autorzy:
Ebrahimi, R.
Powiązania:
https://bibliotekanauki.pl/articles/1535596.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Ln
82.60.Fa
88.05.-b
Opis:
The dual cycle is a better approximation to the modern high speed compression ignition engine than either the Diesel cycle or the Otto cycle. Therefore, this study is aimed at investigating the effects of pressure and cut-off ratios on the dual cycle performance with considerations of heat transfer loss, variable specific heat ratio and friction irreversible losses. By using finite-time thermodynamics theory, the relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are obtained. The results show that if compression ratio is smaller than certain value, the increase of pressure ratio and the decrease of cut-off ratio make the power output bigger. While if compression ratio exceeds certain value, the power output first increases and then starts to decline as pressure ratio and cut-off ratio are increased. With further increase in compression ratio, the power output decreases with increasing pressure ratio and decreasing cut-off ratio. The effects of pressure and cut-off ratios on the variation of the thermal efficiency with compression ratio are similar to those for the power output. The results obtained in this work can provide significant guidance for the performance evaluation and improvement of modern high speed compression ignition engines.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 534-539
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Order in Quantum Compass and Orbital e_{g} Models
Autorzy:
Czarnik, P.
Dziarmaga, J.
Oleś, A.
Powiązania:
https://bibliotekanauki.pl/articles/1029762.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
05.10.Cc
05.70.Fh
75.25.Dk
Opis:
We investigate thermodynamic phase transitions in the compass model and in e_{g} orbital model on an infinite square lattice by variational tensor network renormalization (VTNR) in imaginary time. The onset of nematic order in the quantum compass model is estimated at _{c}/J=0.0606(4). For the e_{g} orbital model one finds: (i) a very accurate estimate of _{c}/J=0.3566± 0.0001 and (ii) the critical exponents in the Ising universality class. Remarkably large difference in frustration results in so distinct values of _{c}, while entanglement influences the quality of _{c} estimation.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 359-361
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Bistability Induced by Additive Colored Noise in the Exciton-Biexciton System
Autorzy:
Gonţia, I. I.
Rotaru, A. H.
Powiązania:
https://bibliotekanauki.pl/articles/1933412.pdf
Data publikacji:
1995-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.40.+j
05.70.Fh
42.65.Pc
Opis:
This paper predicts optical bimodality induced by external additive noise with a finite bandwidth, in the exciton-biexciton system.
Źródło:
Acta Physica Polonica A; 1995, 87, 6; 911-917
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Field Effect on Sound Propagation in Antiferromagnets
Autorzy:
Pawlak, A.
Fechner, B.
Powiązania:
https://bibliotekanauki.pl/articles/1810483.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Jk
62.65.+k
Opis:
On the basis of the theory of phase transitions, a model describing anomalies of sound attenuation coefficient close to the antiferromagnet-paramagnet phase transition in magnetic field was developed. The scaling behaviour of the sound velocity and attenuation coefficient was determined. The physical origin of the two-peak structure in the field dependent ultrasound attenuation observed in a number of antiferromagnets was identified. The theoretical results were compared with experimental results obtained for terbium.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 232-234
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Granger Causality and Transfer Entropy for Financial Returns
Autorzy:
Syczewska, E.
Struzik, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1388215.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
89.20.-a
89.70.Cf
02.50.-r
05.45.Tp
02.70.Rr
Opis:
Granger causality in its linear form has been shown by Barnett, Barrett and Seth [Phys. Rev. Lett. 103, 238701 (2009)] to be equivalent to transfer entropy in case of Gaussian distribution. Generalizations by Hlaváčková-Schindler [Appl. Math. Sci. 5, 3637 (2011)] are applied to distributions typical for biomedical applications. The financial returns, which are of great importance in financial econometrics, typically do not have Gaussian distribution. Generalizations leading to the concept of nonlinear Granger causality (e.g. causality in variance, causality in risk), known and applied in econometric literature, seem to be less known outside this field. In the paper an overview of some of the definitions and applications is given. In particular, we indicate some recent econometric results concerning application of the tests in linear multivariate framework. We emphasize importance of other variants of Granger causality, and need of development of methods reflecting features of financial variables.
Źródło:
Acta Physica Polonica A; 2015, 127, 3A; A-129-A-135
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Finite-Element Flash Method for Measuring Thermal Conductivity of Liquid
Autorzy:
Mamczur, J.
Wasilewski, A.
Więcek, T.
Powiązania:
https://bibliotekanauki.pl/articles/1402572.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
44.05.+e
44.10.+i
07.05.Tp
02.70.Dh
02.60.Ed
Opis:
A laser beam is used to heat a portion of liquid closed in a vessel from the top of it to avoid convection. The temperature is measured at the bottom of the vessel by a laser waveguide sensor. The heating and measuring methods allow using a small amount of liquid of the order of a milliliter fraction. The heat flow through the liquid as well as the surrounding vessel and space is modeled by the finite-element method to calculate the temperature at the bottom vs. time. Thus obtained dependence is used then as a fitting function to get the liquid thermal conductivity among some other fitting parameters.
Źródło:
Acta Physica Polonica A; 2015, 128, 2; 193-195
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical Properties of Aluminum-Matrix-Nanoparticle Composites
Autorzy:
Kazakewitsch, A.
Riehemann, W.
Powiązania:
https://bibliotekanauki.pl/articles/1418512.pdf
Data publikacji:
2012-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.82.Rx
62.40.+i
81.05.-t
81.05.Ni
81.07.Wx
81.20.Ev
81.20.Hy
81.40.Ef
81.70.-q
81.70.Bt
Opis:
Aluminum-matrix-nanoparticle composites were produced by ball milling of micro scale aluminum powder with different additions of 500 nm mean diameter SiC particles in air atmosphere with subsequent consolidation by hot extrusion. The material was investigated in this condition by tensile testing, hot tensile testing, density, hardness, and amplitude dependent damping measurements. The amplitude dependent damping of the material was investigated after slow furnace heating and cooling as after quenching into water to the room temperature. The results of the tensile and hot tensile testing show that the addition of SiC particles lead to a significant increase of tensile strength, but the remaining porosity increased, too. The results obtained for the amplitude dependent damping can be attributed to cracks present in the consolidated material or cracks produced by thermal stresses.
Źródło:
Acta Physica Polonica A; 2012, 122, 3; 516-519
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rise and Fall of Reentrant Phase Transitions in a Coupled Spin-Electron Model on a Doubly Decorated Honeycomb Lattice
Autorzy:
Čenčariková, H.
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032648.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
05.70.Fh
71.27.+a
75.30.Kz
Opis:
Phase diagrams and spontaneous magnetization are rigorously calculated for a coupled spin-electron model on a doubly decorated honeycomb lattice, which accounts for a quantum-mechanical hopping of the mobile electrons on decorating sites, the nearest-neighbor Ising coupling between mobile electrons and localized spins, as well as the further-neighbor Ising coupling between the localized spins placed on nodal sites. The spontaneously ordered ferromagnetic phase, spontaneously ordered antiferromagnetic phase and disordered paramagnetic phase emerge in a phase diagram depending on an electron filling of the decorating sites, a relative size of the hopping term and both considered coupling constants. It is evidenced that a nature and size of the further-neighbor Ising coupling between the localized spins basically influences rise and fall of reentrant transitions close to a phase boundary between the paramagnetic phase and both spontaneously ordered phases.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1021-1023
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Heuristic for Approximating Extreme Negative Price Returns in Financial Markets
Autorzy:
Manhire, J.
Powiązania:
https://bibliotekanauki.pl/articles/1029529.pdf
Data publikacji:
2018-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.70.-c
05.10.-a
89.65.Gh
Opis:
The paper describes the behavior of financial markets as functions of the variables ``price return'' and ``time'' based on the net difference between ask and bid volumes over a unit period, thereby suggesting that at least a negative non-trivial price return extreme exists for a unit period. This admittedly heuristic approach also offers a method for approximating these negative price return extremes for a specific unit period. Limitations and applications are discussed.
Źródło:
Acta Physica Polonica A; 2018, 133, 6; 1408-1413
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mutual Information-Based Hierarchies on Warsaw Stock Exchange
Autorzy:
Fiedor, P.
Powiązania:
https://bibliotekanauki.pl/articles/1388360.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.10.-a
64.60.aq
89.65.-s
89.70.-a
Opis:
A popular method for network analysis of financial markets is a notable part of econophysics research. The networks created in such efforts are focused exclusively on linear correlations between stocks. While Pearson's correlation is the obvious starting point, it would be useful to look at its alternatives as to whether they provide improvements to this methodology, particularly given Pearson's correlation coefficient considers only a limited class of association patterns. We propose to use mutual information-based hierarchical networks, as mutual information is a natural generalisation of Pearson's correlation. We estimate mutual information using naive plug-in estimator as consistent bias is not harmful to this application, however other methods may also be used. We then transform the mutual information into an Euclidean metric and create minimal spanning trees and maximally filtered planar graphs. We apply this methodology to Warsaw Stock Exchange for years between 2000 and 2013, and comment on the differences with the standard methodology, as well as the structural changes on Warsaw Stock Exchange which the study reveals.
Źródło:
Acta Physica Polonica A; 2015, 127, 3A; A-33-A-37
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantum Phase Transition in the One-Dimensional XZ Model
Autorzy:
Brzezicki, W.
Oleś, A.
Powiązania:
https://bibliotekanauki.pl/articles/1810415.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
03.67.-a
05.70.Fh
Opis:
We introduce a one-dimensional XZ model with alternating $σ_i^zσ_{i+1}^z$ and $σ_i^x σ_{i+1}^x$ interactions on even/odd bonds, interpolating between the Ising model and the quantum compass model. We present two ways of its exact solution by: (i) mapping to the quantum Ising models, and (ii) using fermions with spin 1/2. In certain cases the nearest neighbor pseudospin correlations change discontinuously at the quantum phase transition, where one finds highly degenerate ground state of the 1D compass model.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 162-164
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of a Polymer Based Syntactic Foam for High Temperature Applications
Autorzy:
Yazici, M.
Fahr, P.
Shukla, A.
Gunes, S.
Akay, S.
Powiązania:
https://bibliotekanauki.pl/articles/1182911.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Qk
81.70.Bt
81.40.-z
81.05.Lg
Opis:
Syntactic foams are one of the most widely used close cell structured foams. They are used in applications for naval, aeronautical, aerospace, civil, industrial, and automotive engineering due to good acoustical attenuation, excellent strength to weight ratio, vibration isolation, and dielectric properties. These foams are fabricated by incorporation of hollow particles in a matrix material. The most preferred matrix materials are polymers. In this study silicone resin (useful temperature range - 53C to 232°C) was selected as a binder material. Glass bubbles were incorporated into the silicone resin at three different mass percentages (10%, 20%, and 30%). The density of the silicone was reduced more than 50% by 30% glass bubble contribution. The foam mechanical properties were investigated in a room temperature and after heat treatment at 500C by quasi-static compression experiments. Microstructural transitions by the temperature raises were examined by using scanning electron microscopy pictures. It was observed that the increase of glass bubble percentage in silicone rubber enhanced the energy absorption properties in the heat treated and room temperature specimens. Plateau stress and densification amount were improved under quasi-static compression load by the glass bubble percentage increase. It can be said that developed syntactic foams can be used in heat resistant, low weight and high compression strength exigencies.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 526-528
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Power Optimization of a Miller Thermal Cycle with respect to Residual Gases and Equivalence Ratio
Autorzy:
Ebrahimi, R.
Powiązania:
https://bibliotekanauki.pl/articles/1399491.pdf
Data publikacji:
2013-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Ln
82.60.Fa
88.05.-b
88.20.td
Opis:
The performance of an air standard Miller cycle is analyzed using finite-time thermodynamics. The relations between the power output and the compression ratio and between the power output and the thermal efficiency are derived by detailed numerical examples. The results show that, throughout the compression ratio range, the power output decreases with increasing residual gases. The results also show that if compression ratio is less than certain value, the power output decreases with increasing equivalence ratio, while if compression ratio exceeds certain value, the power output first increases and then starts to decrease with increasing equivalence ratio. The conclusions of this investigation are of importance when considering the designs of actual Miller engines.
Źródło:
Acta Physica Polonica A; 2013, 124, 1; 6-10
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhanced Mechanical Performance of Aluminum Glass Fiber Reinforced Foam Material by Cu Modification
Autorzy:
Ertürk, A.
Aydin, I.
Powiązania:
https://bibliotekanauki.pl/articles/1033530.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Bx
81.05.Rm
81.20.Ev
81.70.Bt
Opis:
Glass fiber-reinforced aluminum foam and its modified forms, using 1 and 3 wt.% of Cu, were produced by powder sintering process, using spherical carbamide particles as space holders. The foams with 40 and 60 vol.% porosity fractions were successfully produced after water leaching and sintering procedures. Compression test was performed on foam samples to compare both, the compressive properties and energy absorption behavior of them. The composite foam samples with Cu modification have shown a higher compressive strength than the parent material foam. The average plateau stress and energy absorption capacity of foams produced in this study, achieved via utilizing 3 wt.% Cu, were 7.06 MPa and 3.51 MJ/m³, respectively.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 470-473
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Pre-Forming Process and PVC Foam Reinforcement on the Deformation Behavior of Aluminum Tube under Axial Loading
Autorzy:
Ekşi, S.
Kapti, A.
Genel, K.
Powiązania:
https://bibliotekanauki.pl/articles/1031785.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.-t
81.05.Bx
81.05.Rm
81.40.Lm
81.70.-q
81.05.Pj
Opis:
In this study, the effects of pre-forming and foam reinforcement on the axial compression behavior of circular thin-walled aluminum tubes were experimentally investigated. Compression tests were performed in a computer controlled test machine at the cross-head speed of 1 mm/s. Pre-forming has changed the folding behavior of tube and increased the energy absorbing capacity 1.26 times that of empty tube. The PVC reinforcement has increased the energy absorbing capacity 1.22 times. PVC reinforcement increases the stability of tube wall deformation; hence it positively affects the energy absorption. The energy absorbing capacity of pre-formed and PVC foam reinforced tubes increase approximately 1.4 times that of empty tube. It was however shown that the reinforcement and pre-forming had no significant effect on the maximum load.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 875-878
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Production of Aluminum Glass Fiber Reinforced Foam Synthesized by Space-Holder Technique
Autorzy:
Ertürk, A.
Powiązania:
https://bibliotekanauki.pl/articles/1187253.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Rm
81.05.Bx
83.80.Ab
81.20.Ev
81.70.Bt
Opis:
Aluminum and its reinforced type with glass fiber composite foams were produced by powder sintering process using spherical carbamide particles as a space holder. The foams with 40-60 vol.% porosity fractions were successfully produced after water leaching and sintering methods. Compression test was performed on both of the foam samples for comparing the compressive properties and energy absorption behavior of them. The composite foam samples with glass fiber reinforcement showed higher compressive strength than the parent material foam.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 592-595
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Diagrams of the Spin-1/2 Ising-Heisenberg Model on a Triangle-Hexagon Lattice
Autorzy:
Kiššová, J.
Strečka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1506906.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.30.Rt
05.50.+q
05.70.Jk
75.10.Kt
75.10.Jm
75.30.Kz
Opis:
Ground-state and finite-temperature phase diagrams of a geometrically frustrated spin-1/2 Ising-Heisenberg model on a triangle-hexagon lattice are investigated within the generalized star-triangle mapping transformation. It is shown that the ground state is constituted by two different spontaneously long-range ordered phases and one disordered spin-liquid phase.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 730-731
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diffusive Regime for Critical Sound Attenuation and Dispersion in Magnets
Autorzy:
Pawlak, A.
Błaszak, M.
Powiązania:
https://bibliotekanauki.pl/articles/2013731.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Jk
62.65.+k
Opis:
We consider a new regime of sound propagation in magnetic systems above the critical point. On the basis of a general statistical model including a flow of energy between spin and lattice subsystems we found that there is a region of parameters where the sound attenuation and dispersion can be expressed in a similar way as for noncritical systems for which only the heat conduction matters. Contrary to the case of the classical heat diffusion in the critical magnetic system both the specific heat, entering the reduced frequency, as well as the effective amplitude are frequency and temperature dependent reflecting the critical singularities present in the system near its critical point.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 905-908
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aperiodicity in Equilibrium Systems: Between Order and Disorder
Autorzy:
van Enter, A.
Powiązania:
https://bibliotekanauki.pl/articles/1203443.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Fh
61.44.Br
02.50.Ey
Opis:
Spatial aperiodicity occurs in various models and materials. Although today the most well-known examples occur in the area of quasicrystals, other applications might also be of interest. Here we discuss some issues related to the notion and occurrence of aperiodic order in equilibrium statistical mechanics. In particular, we consider some spectral characterisations, and shortly review what is known about the occurrence of aperiodic order in lattice models at zero and nonzero temperatures. At the end some more speculative connections to the theory of (spin-)glasses are indicated.
Źródło:
Acta Physica Polonica A; 2014, 126, 2; 621-624
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Field Influence on Critical Sound Attenuation and Velocity Variation in Ferromagnets
Autorzy:
Pawlak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1810482.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Jk
62.65.+k
Opis:
The ultrasound velocity and attenuation are investigated in ferromagnets under an application of magnetic field. In the magnetic field six different characteristic regimes are distinguished instead of traditional two (hydrodynamic and critical) found for the case of zero magnetic field. The mean-field Landau-Khalatnikov theory as well as the scaling predictions are given for each regime. Various critical exponents are identified for these regions and compared with the ultrasonic data for MnP. The shift of the ultrasonic attenuation peak under the influence of magnetic field towards higher temperatures is discussed.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 229-231
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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