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Tytuł:
Mathematical Modeling of Heat Effect on Cable Insulation
Autorzy:
Eroglu, E.
Guney, I.
Gunes, I.
Sener, E.
Powiązania:
https://bibliotekanauki.pl/articles/1031951.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.90.+p
88.20.td
Opis:
In the electric power industry, the cost of energy, its longevity and safety of transferring are important problems. Security problems, environmental effects, discharging occurrences and the endurance of the transporters are the problems that exist as a consequence of the high voltage necessity for the transmission of big amounts of energy and which need to be solved. ADSS (all dielectric self-supporting) cables are generally installed on high voltage transmission lines. They are mostly used in such situations, as high temperature, strong winds and direct sunshine and, as the effect, the UV radiation, etc. The solid materials are in use more frequently than gas or liquid ones. Decent dielectric materials need to be sturdy to puncturing and highly invulnerable for mechanical issues. Moreover, they have to perform and resist well the chemical reactions and high temperature, so that they would not be easily effected by the environmental factors. In this study, the mathematical modeling of heat effects on ADSS cables is investigated by using dry band arcing (IEEE 1222 Electrical surface degradation) test method. A heat source is introduced into the test setup, to evaluate the performance of poly-ethylene cable jackets on ADSS cables at different temperatures. Test results indicate that the endurance of the ADSS cables decreases with the increasing temperature.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 539-541
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural Radioactivity and Radiation Hazards in Coals Extracted in Amasya, Turkey
Autorzy:
Boz, M.
Öner, F.
Mavi, B.
Powiązania:
https://bibliotekanauki.pl/articles/1402393.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.85.Nc
92.20.Td
Opis:
Radioactive nuclei were created at the beginning of the Universe and with a long half-life, are still present in Earth's crust. The radiations due to the radionuclides contribute to natural background radiation. This generally occurs in ground-source materials (stone, soil, rocks, etc.) in different concentrations. The levels of radiation are due to the uranium, thorium and potassium present in the material. In this study, the natural radioactivity concentrations of coals extracted in Suluova have been determined using a NaI(Tl) γ -ray spectrometer system. The radium equivalent activities of the samples were all below the recommended limit values (370 Bqkg¯¹). The value of external hazard indices is less than unity.
Źródło:
Acta Physica Polonica A; 2015, 128, 2B; B-360-B-362
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural Radioactivity Levels on Surface Water of Nemrut Crater Lake (Bitlis, Turkey)
Autorzy:
Kuluöztürk, M.
Doğru, M.
Powiązania:
https://bibliotekanauki.pl/articles/1402433.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.85.Nc
92.20.Td
Opis:
Nemrut Crater lake is the world's second largest and largest of Turkey crater lake and its altitude is 2250 m. The aim of this study is to determine radioactivity levels of the lake surface water. In this study water samples were collected from 33 points of the lake surface. The gross alpha and gross beta activity concentrations were determined by using ultra low level α/β counter. The mean gross alpha and beta activity concentrations were found to be 77.69 mBqL¯¹ and 115.36 mBqL¯¹ respectively. Contour maps were produced for gross alpha and beta concentrations of the lake.
Źródło:
Acta Physica Polonica A; 2015, 128, 2B; B-397-B-399
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of Natural Radioactivity from $\text{}^{232}Th$ with Gamma-Ray Spectrometer in Dereköy-Yazır (Southwestern Anatolia)
Autorzy:
Uyanik, N.
Öncü, Z.
Uyanik, O.
Akkurt, İ.
Powiązania:
https://bibliotekanauki.pl/articles/1402500.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
92.20.Td
29.30.-h
Opis:
This study presents new data on the baseline concentrations of Thorium over the Dereköy-Yazır (Ağlasun-Burdur) volcanic area. Portable gamma-ray spectrometer was used for natural thorium mapping. In situ measurements were made in the field, in the area of 7.5 km² at 165 points. Variations in the Th concentration in the surficial environment of the Dereköy-Yazır region appear to be related to bedrock lithology. The measured thorium concentration varies between 0.68-36 ppm, in the studied area. The highest concentration values were obtained from volcanic rocks. The outcropping volcanic rocks in the region are Pliocene alkaline basalts.
Źródło:
Acta Physica Polonica A; 2015, 128, 2B; B-441-B-442
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation of Thermally-Activated Electron Traps in GaAs/AlAs/GaAs Heterostructures in Low-Frequency Noise Measurements
Autorzy:
Przybytek, J.
Stankiewicz, R.
Gryglas-Borysiewicz, M.
Baj, M.
Cavanna, A.
Faini, G.
Powiązania:
https://bibliotekanauki.pl/articles/2048142.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.50.Td
73.40.Gk
Opis:
During our investigations of tunneling process in thin 7 nm thick GaAs/AlAs/GaAs vertical single-barrier tunneling structure with Si δ-doping inside the barrier we have observed fluctuations of the tunneling current which exhibited large Lorentzian noise with intensity depending on biasing voltage. We have shown that Lorentzian noise originates from multilevel random telegraph noise of the small number of fluctuators which influence the tunneling process. Time-domain analysis of the current noise measured for temperatures between 4.2 K and 50 K enabled to determine the thermal activation energies of these fluctuators lying between 0.8 and 3 meV.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 723-725
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effects of Cycle Temperature and Cycle Pressure Ratios on the Performance of an Irreversible Otto Cycle
Autorzy:
Ust, Y.
Sahin, B.
Safa, A.
Powiązania:
https://bibliotekanauki.pl/articles/1493409.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Ln
88.05.-b
88.20.td
Opis:
This paper reports the thermodynamic optimization based on the maximum mean effective pressure, maximum power and maximum thermal efficiency criteria for an irreversible Otto heat engine model which includes internal irreversibility resulting from the adiabatic processes. The mean effective pressure, power output, and thermal efficiency are obtained by introducing the compression ratio, cycle temperature ratio, specific heat ratio and the compression and expansion efficiencies. Optimal performance and design parameters of the Otto cycle are obtained analytically for the maximum power and maximum thermal efficiency conditions and numerically for the maximum mean effective pressure conditions. The results at maximum mean effective pressure conditions are compared with those results obtained by using the maximum power and maximum thermal efficiency criteria. The effects of the cycle temperature ratio and cycle pressure ratio on the general and optimal performances are investigated.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 412-416
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cross-Correlations and Charge Pumping in Shot Noise οf Coupled Quantum Dot System
Autorzy:
Michałek, G.
Bułka, B.
Powiązania:
https://bibliotekanauki.pl/articles/1791333.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.Hk
73.63.Kv
73.50.Td
Opis:
We analyze current auto- and cross-correlations in the system of two capacitively coupled large quantum dots. Our attention is focused on the strong inter-dot coupling when an electron transfer through one of the quantum dots induces charge pumping through the second quantum dot. We show individual contributions to shot noise from various tunneling processes in the charge space.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 879-881
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancement of Current Auto- and Cross-Correlations in Double Quantum Dots
Autorzy:
Michałek, G.
Bułka, B.
Powiązania:
https://bibliotekanauki.pl/articles/1810396.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.Hk
73.63.Kv
73.50.Td
Opis:
Studies of an enhancement of current shot noises are presented for a device of two large quantum dots coupled capacitively. We analyze current-current correlation functions, and show that a dynamical Coulomb blockade is responsible for an enhancement of the Fano factors. This process can lead also to an electron bunching and positive current cross-correlations. Our theoretical results are discussed in light of recent shot noise experiments.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 117-119
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Negative Differential Resistance and Super-Poissonian Shot Noise in a System of Single Electron Transistors
Autorzy:
Michałek, G.
Bułka, B. R.
Powiązania:
https://bibliotekanauki.pl/articles/2028848.pdf
Data publikacji:
2001-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.Hk
73.40.Gk
73.50.Td
Opis:
Currents and their fluctuations in two capacitively coupled single electron transistors were studied within the sequential tunneling approach. A special attention was focused on the effect of the negative differential resistance, which appears due to the Coulomb interactions of accumulated charges on both the single electron transistors. In this case large polarization fluctuations are activated, which results in a significant enhancement of the current shot noise.
Źródło:
Acta Physica Polonica A; 2001, 100, 3; 431-436
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Current Fluctuations in Single Barrier Vertical GaAs/AlAs/GaAs Tunneling Devices
Autorzy:
Przybytek, J.
Baj, M.
Powiązania:
https://bibliotekanauki.pl/articles/2047380.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.50.Td
73.40.Gk
73.43.Jn
Opis:
We report the experimental results of the low temperature (T = 4.2 K) low-frequency current fluctuations measurements in the single-barrier resonant tunneling GaAs/AlAs/GaAs device with Siδ-doping in the center of the 10 nm thick AlAs barrier. The dimensions of the device were 200μm by 200μm. For the biasing voltages 0.1 V<|U|<1 V we observed the Fano factors between F = 0.7 and F = 0.95. We explain it by the existence of the trapping centers/imperfections/resonant levels inside the barrier participating in the transport for this range of voltages. Only for the smallest biasing voltages the Fano factor tends to F = 1, expected for a highly nontransparent barrier.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 221-226
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Expansion-Compression Ratio on Performance of the Miller cycle
Autorzy:
Ebrahimi, R.
Powiązania:
https://bibliotekanauki.pl/articles/1418112.pdf
Data publikacji:
2012-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Ln
82.60.Fa
88.05.-b
88.20.td
Opis:
The objective of this study is to analyze the effect of expansion-compression ratio on the performance of dual cycle. Using finite-time thermodynamics, the relations between thermal efficiency, power output and compression ratio for an air standard Miller cycle have been derived. In the model, the nonlinear relation between the specific heats of working fluid and its temperature, the frictional loss computed according to the mean velocity of the piston, and heat transfer loss are considered. The results show that the power output first increases with the increasing expansion-compression ratio and then starts to decrease. Comparisons of the power output of the Miller, Otto, and Atkinson cycles show that if compression ratio is less than certain value, the power output for Otto cycle is higher, while if compression ratio exceeds certain value, the power output for the Miller cycle is higher. With further increase in compression ratio, the power output for Atkinson cycle is higher. In high compression ratio, the power output of the Miller cycle is higher. The results obtained in the present study provide guidance to the performance evaluation and improvement for practical internal combustion engines.
Źródło:
Acta Physica Polonica A; 2012, 122, 4; 645-649
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statistics of Conductance and Shot-Noise Power for Chaotic Cavities
Autorzy:
Sommers, H.-J.
Wieczorek, W.
Savin, D. V.
Powiązania:
https://bibliotekanauki.pl/articles/2047832.pdf
Data publikacji:
2007-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
73.50.Td
05.45.Mt
73.63.Kv
Opis:
We report on an analytical study of the statistics of conductance, g, and shot-noise power, p, for a chaotic cavity with arbitrary numbers N$\text{}_{1,2}$ of channels in two leads and symmetry parameterβ = 1, 2, 4. With the theory of Selberg's integral the first four cumulants of g and first two cumulants of p are calculated explicitly. We give analytical expressions for the conductance and shot-noise distributions and determine their exact asymptotics near the edges up to linear order in distances from the edges. For 0 < g < 1 a power law for the conductance distribution is exact. All results are also consistent with numerical simulations.
Źródło:
Acta Physica Polonica A; 2007, 112, 4; 691-697
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport in Quantum Structures of Diluted Magnetic Semiconductors
Autorzy:
Jaroszyński, J.
Powiązania:
https://bibliotekanauki.pl/articles/2011139.pdf
Data publikacji:
1999-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.50.Td
72.15.Rn
73.61.Ga
75.50.Lk
Opis:
This paper reviews recent millikelvin studies of magnetoconductance and noise in nanostructures of a diluted magnetic semiconductor n-Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te. These studies were particularly rewarding for probing the influence of magnetic ions upon mesoscopic phenomena. The accumulated results demonstrated the existence of a new driving mechanism of the universal conductance fluctuations in magnetic systems. Several signatures of spin-glass freezing were observed, such as the appearance of 1/f conductance noise, aging, thermal, and magnetic irreversibilities as well as a strong increase in the amplitude of both conductance fluctuations and noise when temperature and the magnetic field were lowered below the freezing line. A statistical analysis of conductance noise made it possible to investigate the nature of excitations in spin-glass phase, and to discriminate between competing theoretical models.
Źródło:
Acta Physica Polonica A; 1999, 96, 5; 641-650
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Current Fluctuations in Ferromagnetic Tunnel Junctions
Autorzy:
Bułka, B. R.
Martinek, J.
Michałek, G.
Barnaś, J.
Powiązania:
https://bibliotekanauki.pl/articles/2013034.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.70.Pa
73.50.Td
73.23.Hk
73.40.Gk
Opis:
Current shot noise in a double junction consisting of a small metallic grain connected to two ferromagnetic electrodes is analysed in the limit of sequential tunneling. We show that, apart from charge fluctuations, there are strong spin fluctuations. We also show that two distinct relaxation processes can be distinguished in the frequency dependent current noise: one in a low frequency range and corresponding to spin fluctuations and another one in a high frequency range corresponding to charge fluctuations.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 423-426
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

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