Temat: 05.60.Cd - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Spin Resistivity in Magnetic Materials
Autorzy:: Diep, H.
Magnin, Y.
Hoang, Danh-Tai
Powiązania:: https://bibliotekanauki.pl/articles/1426671.pdf
Data publikacji:: 2012-05
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 75.76.+j
05.60.Cd
Opis:: We show in this paper recent results on the spin resistivity in magnetically ordered materials obtained by Monte Carlo simulations. We discuss its behavior as a function of temperature in various types of crystal: ferromagnetic, antiferromagnetic, and frustrated spin systems. In the model used for simulations, we take into account the interaction between itinerant spins and that between lattice spins and itinerant spins. We also include a chemical potential term, as well as an electric field. We study in particular the behavior of the spin resistivity at and near the magnetic phase transition where the effect of the magnetic ordering is strongest. In ferromagnetic crystals, the spin resistivity shows a sharp peak very similar to the magnetic susceptibility. This can be understood if one relates the spin resistivity to the spin-spin correlation as suggested in a number of theories. The dependence of the shape of the peak on physical parameters such as carrier concentration, magnetic field strength, relaxation time etc. is discussed. In antiferromagnets, the peak is not so pronounced and in some cases it is absent. Its direct relationship to the spin-spin correlation is not obvious. As for frustrated spin systems with strong first-order transition, the spin resistivity shows a discontinuity at the phase transition. To show the efficiency of the simulation method, we compare our results with recent experimental data performed on semiconducting MnTe of NiAs structure. We observe a very good agreement with experiments on the spin resistivity in the whole range of temperature.
Źródło:: Acta Physica Polonica A; 2012, 121, 5-6; 985-991
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

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

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Skocz do pozycji: 3.

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

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Skocz do pozycji: 4.

Tytuł:: Research of Particle Transport with External Driving Force and Entropy Barrier
Autorzy:: Li, S.
Zhang, Z.
Chen, D.
Powiązania:: https://bibliotekanauki.pl/articles/1398914.pdf
Data publikacji:: 2016-06
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 05.40.Jc
05.40.-a
05.10.Gg
05.60.Cd
Opis:: Transport of Brownian particle moving along a three-dimensional throat-like channel is investigated in the presence of an external constant force. The solution of the Fick-Jacobs equation in the situation is solved, and the probability current density and particle current describing the motion of particle are obtained. It is found that entropy barrier and external force can reverse the direction of particle current. The motion of Brownian particle can be tuned by the entropy barrier and the external force.
Źródło:: Acta Physica Polonica A; 2016, 129, 6; 1105-1108
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Study of Ti, V and Their Oxides-Based Thin Films in the Search for Hydrogen Storage Materials
Autorzy:: Tarnawski, Z.
Zakrzewska, K.
Kim-Ngan, N.-T.
Krupska, M.
Sowa, S.
Drogowska, K.
Havela, L.
Balogh, A.
Powiązania:: https://bibliotekanauki.pl/articles/1401913.pdf
Data publikacji:: 2015-09
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 81.15.Cd
68.49.-h
61.05.C-
68.60.-p
Opis:: Thin film series consisting of Ti, V, TiO₂ and V₂O₅ layer with different layer geometries, sequences and thicknesses have been prepared by the sputtering technique. The hydrogen depth profile of selected films upon hydrogen charging at 1 bar and/or hydrogenation at pressure up to 102 bar was determined by using secondary ion mass spectrometry and nuclear reaction analysis using a N-15 beam. The highest hydrogen storage with a concentration up to 50 at.% was found in the pure Ti and Ti-contained layer, while it amounts to around 30% in the metallic Ti-V-Ni layer. Hydrogen can diffuse through the TiO₂ layer without accumulation, but can be stored in the VO₂ layer in some cases. Hydrogen can remove the preferential Ti orientation in the films and induce a complete transition of V₂O₅ into VO₂ in the films.
Źródło:: Acta Physica Polonica A; 2015, 128, 3; 431-439
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Ultraviolet Detectors Based on ZnO:N Thin Films with Different Contact Structures
Autorzy:: Ievtushenko, A.
Lashkarev, G.
Lazorenko, V.
Karpyna, V.
Sichkovskyi, V.
Kosyachenko, L.
Sklyarchuk, V.
Sklyarchuk, O.
Bosy, V.
Korzhinski, F.
Ulyashin, A.
Khranovskyy, V.
Yakimova, R.
Powiązania:: https://bibliotekanauki.pl/articles/1811930.pdf
Data publikacji:: 2008-11
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 81.05.Dz
81.15.Cd
85.60.Dw
72.40.+w
Opis:: Al/ZnO:N/Al and Ni/ZnO:N/Al diode photodetectors fabricated by dc magnetron sputtering of ZnO:N films on p-Si substrates are studied. The photocurrent-to-dark current ratio equal to 250 at λ= 390 nm and the time constant of photoresponse about 10 μs for Al/ZnO:N/Al structures with 4 μm interdigital spacing was achieved. The Ni/ZnO:N/Al diode structure has the rectification ratio ≈10² at bias 1 V, the maximal responsivity about 0.1 A/W is observed at 365 nm, and the measured time constant of photoresponse is about 100 ns.
Źródło:: Acta Physica Polonica A; 2008, 114, 5; 1123-1129
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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