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Tytuł:
Sound Attenuation at High Temperatures in Pt
Autorzy:
Singh, R. K.
Pandey, K. K.
Powiązania:
https://bibliotekanauki.pl/articles/2044642.pdf
Data publikacji:
2006-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.Dc
62.65.+k
Opis:
Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic loss was evaluated in VIII group transition metal Pt in a wide temperature range (100 K to 1500 K) for longitudinal and shear waves along〈100〉, 〈110〉 and〈111〉 directions and for shear waves polarised along different directions. Electrostatic and Born-Mayer potentials were used to obtain second and third order elastic constants, taking nearest-neighbour distance and hardness parameter as input data. Second and third order elastic constants data obtained at different temperatures were used to obtain Gruneisen parameters and non-linearity or anisotropy parameters which in turn were used to evaluate (α/f$\text{}^{2}$)$\text{}_{l}$ and (α/f$\text{}^{2}$)$\text{}_{s}$ in Akhiezer regime. The results were discussed and it was found that at lower temperatures (α/f$\text{}^{2}$) increases rapidly with temperature and then rate of increase becomes very small. Contribution to the total attenuation due to thermoelastic loss is negligible so that due to phonon-phonon interaction establishing that major part of energy from sound wave is removed due to interaction with thermal phonons (lattice vibrations).
Źródło:
Acta Physica Polonica A; 2006, 109, 2; 219-228
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Disturbances in a Semi-Infinite Piezoelectric Medium Coated with a Perfectly Conducting Thin Film under the Influence of Time-Dependent Flow of Heat for a Finite Interval
Autorzy:
Munshi, T. K.
Kundu, K. K.
Mahalanabis, R. K.
Powiązania:
https://bibliotekanauki.pl/articles/1930956.pdf
Data publikacji:
1994-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.70.+a
Opis:
An attempt was made to investigate analytically the mechanical behaviour of a semi-infinite piezoelectric medium coated with a perfectly conducting thin film under the influence of time-dependent flow of heat at the finite end. The problem involves the interaction of three fields, viz. electrical, mechanical and thermal, and the solution was obtained with the aid of operational calculus. The resultant displacement consists of a time-dependent, as well as a time-independent part and the variation of displacements exhibits an arc of a parabola.
Źródło:
Acta Physica Polonica A; 1994, 85, 3; 585-592
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical Response in an N-Electrode Piezo-Quartz Bar under Electrical and Thermal Excitations
Autorzy:
Munshi, T. K.
Kundu, K. K.
Mahalanabis, R. K.
Powiązania:
https://bibliotekanauki.pl/articles/1933453.pdf
Data publikacji:
1995-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.65.-j
77.70.+a
Opis:
The mechanical response in an N-electrode piezo-quartz bar where two consecutive electrodes are separated by an unelectroded region has been studied under electrical and thermal excitations. The bar is subjected to a periodic polarization gradient and a constant flow of heat. The method of operational calculus and Green's function has been used to solve the problem. For time scale ranging from 0.1 to 1.0 s the response becomes a linear function of time and is of the order of 10$\text{}^{-8}$ m.
Źródło:
Acta Physica Polonica A; 1995, 87, 6; 995-1002
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Excitons and Phonons in GaN. Magnetooptical and Spatially Resolved Investigations
Autorzy:
Hoffmann, A.
Eckey, L.
Siegle, H.
Kaschner, A.
Christen, J.
Bertram, F.
Liu, Q. K. K.
Powiązania:
https://bibliotekanauki.pl/articles/1968986.pdf
Data publikacji:
1998-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.-y
78.40.Fy
78.45.+h
Opis:
A comprehensive study of the direct photoluminescence from free-exciton states in GaN using polarization-dependent and magnetooptical measurements is presented. We measured and identified fine-structure splittings in the n=1 state of the A-exciton. From the magnetoluminescence data obtained in fields up to 15 T we determined the g-values of the conduction and valence bands parallel and perpendicular to the c-axis. Self-organized hexagonal GaN pyramids of 5 μm width and covered by six {11̲01} side facets were investigated by spatially resolved cathodoluminescence and micro-Raman spectroscopy. Beside a narrow luminescence peak at 355 nm, originating from the 2 μm thick GaN layer, an additional broad luminescence band was observed from the GaN pyramids around a wavelength of 357 nm. A strong energy shift is found along the {11̲01} pyramidal facets and directly visualized by monochromatic cathodoluminescence images and line scans. In GaN epilayers grown on GaAs substrates a series of sharp modes in the range between 60 cm$\text{}^{-1}$ and 250 cm$\text{}^{-1}$ for temperatures below 100 K was found. The intensities of these modes increased drastically with decreasing temperature. Raman excitation spectra showed a maximum between 514.5 nm and 568 nm. A comparison of spatially resolved investigations with that of intentionally doped GaN epilayers showed that the in-diffusion of As from the substrate plays an important role. Raman spectra as a function of external fields, like magnetic field and hydrostatic pressure, gave additional information about the defect type and the underlying scattering mechanism.
Źródło:
Acta Physica Polonica A; 1998, 94, 2; 125-137
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Study of the Phase Transitions in Potassium Hydrogen Sulphate KHSO$\text{}_{4}$
Autorzy:
Tahoon, K. K.
Abosehly, A. M.
Abdel-Kader, M. M.
El-Sharkawy, A. A.
El-Mansi, F. M
Powiązania:
https://bibliotekanauki.pl/articles/1931565.pdf
Data publikacji:
1994-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.-f
64.70.-p
Opis:
We report on some thermal properties (specific heat capacity C$\text{}_{p}$, thermal conductivity λ, and thermal diffusivity σ) in addition to the differential thermal analysis thermogram and thermogravimetric analysis for potassium hydrogen sulphate (KHS), KHSO$\text{}_{4}$. The accurate measurements of the above-mentioned parameters as functions of temperature revealed that the compound undergoes two structural phase transitions around 100°C and 175°C. It seems also likely that the compound behaves as a poorly conducting material and hence the maul mechanism of the heat transfer is due to phonons. The data are correlated to the crystal structure including the two different HSO¯$\text{}_{4}$ ions.
Źródło:
Acta Physica Polonica A; 1994, 86, 3; 349-355
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effects of Aging on the Hardness and Wear Behaviour of 2124 Al Alloy/B₄C Composites
Autorzy:
Öksüz, K.
Oskay, K.
Powiązania:
https://bibliotekanauki.pl/articles/1401388.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.40.Cd
88.30.mj
81.05.Ni
Opis:
The particulate reinforced aluminum alloy matrix composites are being increasingly used for wear component applications. The influence of matrix aging treatment on wear behavior in a powder metallurgy 2124 Al-B₄C composite was investigated. The aging responses of 2124 Al-B₄C metal matrix composite (MMC) and unreinforced matrix alloy are studied and related to variations in wear resistance properties. The MMC is aged resolution treated. Accelerated aging occurs in both MMC conditions, compared with unreinforced alloy. Wear resistance and hardness were substantially higher in the reinforced alloys. The effects of the percentage of boron carbide addition on the microstructure, hardness and wear tests of the produced material are discussed. The effects of the age hardening process are also considered.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1367-1369
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Infrared Sensor for Eye Tracking in a Harsh Car Environment
Autorzy:
Różanowski, K.
Murawski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1418034.pdf
Data publikacji:
2012-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.30.Sy
42.30.Tz
42.30.Va
Opis:
The paper presents the optical sensor which is built for EyeTracker operating in car harsh environment. The sensor is based on USB high speed video infrared camera. Additional hardware was designed for control and emission of infrared light as well. The designed hardware and software of the sensor are described in the paper. Some results of work, including video processing, are also presented.
Źródło:
Acta Physica Polonica A; 2012, 122, 5; 874-879
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Sensor to Monitor Pupillary Light Reflex
Autorzy:
Różanowski, K.
Murawski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1399401.pdf
Data publikacji:
2013-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.66.Ct
42.30.Va
07.05.Pj
Opis:
The aim of the paper is to describe design of an optical sensor intended to analyze pupillary light reflex. It also presents the results of physiological adaptation mechanisms in human eye, i.e. response of the iris to changes in the intensity of light that falls on the retina of the eye under conditions of sensory deprivation. Pupillary light reflex is a closed loop nerve reflex. It controls the amount of light that reaches the retina. Based on the test results, an optical sensor was designed, fabricated and correctly calibrated. In comparative tests with the use of $F^2D$ Fit-For-Duty, a commercial system by AMTech, selected pupillographic parameters were primarily evaluated (baseline pupil diameter, oscillations, reflex latency, maximum reaction time, pupil constriction time, pupil dilation time, and constriction amplitude) under conditions of diminished alertness, reduced ability to concentrate, increasing fatigue, and drowsiness. The solution comes as part of a mobile pupillography device intended to be assembled in cars and airplanes to identify conditions of lower alertness, reduced ability to concentrate, increasing fatigue and drowsiness in drivers, pilots and traffic controllers, and to trigger alarm and preventive measures, if necessary.
Źródło:
Acta Physica Polonica A; 2013, 124, 3; 558-562
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoinduced $sp^3$ Nanosize Domain with Frozen Shear Displacement in Graphite
Autorzy:
Nishioka, K.
Nasu, K.
Powiązania:
https://bibliotekanauki.pl/articles/1490002.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Nd
61.48.Gh
31.15.xv
05.40.-a
Opis:
A novel $sp^3$-bonded nanosize domain, known as a diaphite which is an intermediate state between a graphite and a diamond, is generated by the irradiation of visible laser pulse onto a graphite crystal. The $sp^3$ structure is well stabilized by shear displacement between neighboring graphite layers. We theoretically study the interlayer $sp^3$ bond formation with frozen shear displacement in a graphite crystal, using a classical molecular dynamics and a semi-empirical Brenner potential. We show that a pulse excitation under the fluctuation of shearing motion of carbons in an initial state can generate interlayer $sp^3$ bonds which freeze the shear, though no frozen shear appears if there is no fluctuation initially. Moreover, we investigate a pulse excitation under the coherent shearing motion and consequently obtain that the $sp^3$-bonded domain with frozen shear is efficiently formed. We conclude that the initial shear is important for the photoinduced $sp^3$ nanosize domain formation.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 350-354
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Single-Crystal X-Ray Diffractometry Using Synchrotron Radiation
Autorzy:
Eichhorn, K.
Hümmer, K.
Powiązania:
https://bibliotekanauki.pl/articles/1931648.pdf
Data publikacji:
1994-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.85.+n
61.10.Jv
Opis:
The outstanding properties of synchrotron radiation, in particular its high brilliancy over a wide spectral range, its low divergence, its polarization properties, and the pulsed time structure, extend the range of single-crystal X-ray diffractometry to experiments which are not feasible with conventional sources, such as sealed X-ray tubes or rotating anode equipment. Data collection techniques are strongly influenced by the general aims of a diffraction experiment, by the sample quality, its absorption and scattering power, as well as by the reflection profile shape and the instrumental resolution function. Often, the sample properties play a crucial role, and not all samples may be suitable for data collection with synchrotron X-rays. The time-dependence of the primary beam intensity and of its polarization state requires monitoring and normalization to monitor counts, which complicates data collection and data reduction due to sources of both random and systematic errors not known from conventional X-ray sources. There is almost no utilization of X-ray diffraction that cannot profit from the use of synchrotron radiation. X-ray diffraction at a synchrotron radiation source can yield structure factors of an unprecedented quality, provided proper attention is given to sample properties, to data collection strategy and data evaluation procedures. Though little is gained for strong reflections, the improvement is very pronounced for the weaker reflections, including high-order reflections, which can be measured in much shorter time than with conventional X-ray sources. However, synchrotron radiation does not provide a solution to all problems, in some cases conventional laboratory X-ray sources may be more appropriate than synchrotron radiation. Taking into account the limited access to synchrotron radiation sources, X-ray diffraction with synchrotron radiation can only supplement, but not replace conventional X-ray sources and diffraction techniques.
Źródło:
Acta Physica Polonica A; 1994, 86, 4; 497-512
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure of an Al-Fe-Ni Decagonal Quasicrystal Studied by Cs-Corrected STEM
Autorzy:
Yasuhara, A.
Yamamoto, K.
Yubuta, K.
Hiraga, K.
Powiązania:
https://bibliotekanauki.pl/articles/1373700.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.-f
Opis:
The structure of an Al-Fe-Ni decagonal quasicrystal with two quasiperiodic planes along the periodic axis in an $Al_{72}Ni_{24}Fe_4$ alloy has been examined by spherical aberration (Cs)-corrected scanning transmission electron microscopy with high-angle annular dark-field and annular bright-field techniques. The transition-metal atoms and mixed sites (MSs) of Al and transition-metal atoms are represented as separated bright dots in the observed high-angle annular dark-field scanning transmission electron microscopy images, and consequently the arrangements of transition-metal atoms and mixed sites on the two quasiperiodic planes can be directly determined. The transition-metal atoms are arranged on a pentagonal tiling of an edge-length of 0.76 nm. The close examination of observed annular bright-field- and high-angle annular dark-field scanning transmission electron microscopy images indicates the existence of large decagonal columnar clusters with 3.2 nm diameter, and their arrangement on pentagonal, thin rhombic and squashed hexagonal tiles with an edge-length of 3.2 nm. The arrangements of transition-metal atoms in these three tiles are placed on an ideal pentagonal tiling with an edge-length of 3.2 nm, which is generated by the projection of a five-dimensional hyper-cubic lattice. The vertices are denoted by 5D hyper-cubic indices and then they are projected on the occupation domains in perpendicular space. The arrangement of Al atoms as well as transition-metal atoms and mixed sites in the large decagonal atom cluster with about 3.2 nm diameter is interpreted from the observed high-angle annular dark-field- and annular bright-field scanning transmission electron microscopy ABF-STEM images.
Źródło:
Acta Physica Polonica A; 2014, 126, 2; 637-640
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Indifferents as an Interface between Contra and Pro
Autorzy:
Malarz, K.
Kułakowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1538566.pdf
Data publikacji:
2010-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
89.65.-s
87.23.Ge
89.65.Ef
89.75.-k
89.75.Fb
Opis:
In most sociophysical simulations on public opinion, only two opinions are allowed: Pro and Contra. However, in all political elections many people do not vote. Here we analyse two models of dynamics of public opinion, taking into account Indifferent voters: (i) the Sznajd model with symmetry Pro-Contra, (ii) the outflow one move voter model, where Contra's are converted to Indifferent by their Pro neighbours. Our results on the Sznajd model are in an overall agreement with the results of the mean field approach and with those known from the initial model formulation. The simulation on the voter model shows that an amount of Contra's who remain after convertion depends on the network topology.
Źródło:
Acta Physica Polonica A; 2010, 117, 4; 695-699
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pattern Recognition Algorithm for Eye Tracker Sensor Video Data Analysis
Autorzy:
Murawski, K.
Różanowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1399387.pdf
Data publikacji:
2013-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.30.Sy
42.30.Va
07.05.Pj
Opis:
The aim of the paper is to discuss research conducted at the Military University of Technology as well as the Military Institute of Aviation Medicine. The essence of the research is to develop a pattern recognition algorithm for the analysis of data received from an eye tracker sensor. Data analysis can be done using computer vision algorithms. In the article the state of the art pattern recognition algorithms were presented. Particular attention was paid to the possibilities and limitations of their use. The main part of the paper is the presentation of the author's pattern recognition algorithm. In the paper we have also shown the results obtained by other techniques of image processing, which are frequently used to determine the position of the pupil of the eye on the image.
Źródło:
Acta Physica Polonica A; 2013, 124, 3; 509-512
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One-Loop Perturbative Corrections for Noncommutative N = 1 Supesymetric Gauge Theories in two Dimensions
Autorzy:
Zaibak, K.
Bouakaz, K.
Powiązania:
https://bibliotekanauki.pl/articles/1402377.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
14.80.Ly
11.30.Pb
14.80.Da
12.60.Jv
Opis:
We calculate the contribution of the tadpole for gauge field of the noncommutative gauge supersymmetric theory in two dimensions in Minkowski space. We have found two types of divergences UV/IR similar to those found in the contribution of the ghost field loop.
Źródło:
Acta Physica Polonica A; 2015, 128, 2B; B-330-B-331
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bounded confidence model: addressed information maintain diversity of opinions
Autorzy:
Malarz, K.
Kułakowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1409050.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.23.Ge
07.05.Tp
64.60.aq
Opis:
A community of agents is subject to a stream of messages, which are represented as points on a plane of issues. Messages are sent by media and by agents themselves. Messages from media shape the public opinion. They are unbiased, i.e. positive and negative opinions on a given issue appear with equal frequencies. In our previous work, the only criterion to receive a message by an agent is if the distance between this message and the ones received earlier does not exceed the given value of the tolerance parameter. Here we introduce a possibility to address a message to a given neighbour. We show that this option reduces the unanimity effect, what improves the collective performance.
Źródło:
Acta Physica Polonica A; 2012, 121, 2B; B-86-B-88
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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