Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Physics

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 27931 - 27960 of 36711

Full-Text Articles in Physical Sciences and Mathematics

Ac Conductivity And Dielectric Study Of Chalcogenide Glasses Of Se-Te-Ge System, Fathy Salman Jan 2004

Ac Conductivity And Dielectric Study Of Chalcogenide Glasses Of Se-Te-Ge System, Fathy Salman

Turkish Journal of Physics

The ac conductivity and dielectric properties of glassy system Se_{x}Te_{79 - x}Ge_{21}, with x = 11, 14, 17 at.%, has been studied at temperatures 300 to 450 K and over a wide range of frequencies (50 Hz to 500 kHz). Experimental results indicate that the ac conductivity and the dielectric constants depend on temperature, frequency and Se content. The conductivity as a function of frequency exhibited two components: dc conductivity \sigma _{dc}, and ac conductivity \sigma _{ac}, where \sigma _{ac} \sim \omega ^{s}. The mechanism of ac conductivity can be reasonably interpreted in terms of the correlated barrier hopping model …

Go to article

Raman Scattering In Layered Cdingas_4, Aydin Kulibekov Jan 2004

Raman Scattering In Layered Cdingas_4, Aydin Kulibekov

Turkish Journal of Physics

Raman scattering spectra of CdInGaS_4 crystals grown by the chemical transport method were measured at room and liquid-nitrogen temperatures. Band pairs at 29-38, 43-48 and 60-65 cm^{-1} are reported for the first time. The origin of these bands is attributed to the Davydov doublets, arising due to a small interlayer interaction. Seventeen bands observed in the Raman spectra are assigned to normal modes on the basis of the C_{3v}^1 space group. This modification contains two layers per unit cell and do not have inversion symmetry. It is shown that the crystals grown from the vapor phase and by the Bridgman …

Go to article

The Hypervirial-Padé Summation Method Applied To The Anharmonic Oscillator, Altuğ Arda Jan 2004

The Hypervirial-Padé Summation Method Applied To The Anharmonic Oscillator, Altuğ Arda

Turkish Journal of Physics

The energy eigenvalues of the anharmonic oscillator characterized by the cubic potential for various eigenstates are determined within the framework of the hypervirial-Padé summation method. For this purpose the E[3, 3] and E[3, 4] Padé approximants are formed to the energy perturbation series and given the energy eigenvalues up to fourth order in terms of the anharmonicity parameter \lambda.

Go to article

Scas Officers And Council Members 2004 - 2005 Jan 2004

Scas Officers And Council Members 2004 - 2005

Journal of the South Carolina Academy of Science

No abstract provided.

Go to article

Realizations Of The Osp(2,1) Superalgebra And Related Physical Systems, Hayri̇ye Tütüncüler, Ramazan Koç Jan 2004

Realizations Of The Osp(2,1) Superalgebra And Related Physical Systems, Hayri̇ye Tütüncüler, Ramazan Koç

Turkish Journal of Physics

Eigenvalues and eigenfunction of two-boson 2 \times 2 Hamiltonians in the framework of the superalgebra osp(2,1) are determined by presenting a similarity transformation. The Hamiltonians include two bosons and one fermion have been transformed in the form of the one variable differential equations and the conditions for its solvability have been discussed. It is observed that the Hamiltonians of the various physical systems can be written in terms of the generators of the osp(2,1) superalgebra and under some certain conditions their eigenstates can exactly be obtained. In particular, the procedure given here is useful in determining eigenstates of the Jaynes-Cummings …

Go to article

Analysis Of One-Nucleon Transfer Cross-Sections, A. K. A. R. Al-Farra Jan 2004

Analysis Of One-Nucleon Transfer Cross-Sections, A. K. A. R. Al-Farra

Turkish Journal of Physics

The angular distributions of ^{26}Mg(^3H,^2H)^{27}Mg and ^{30}Si(^3H,^2H)^{31}Si reactions have been successfully studied using distorted wave Born approximation (DWBA) calculations. The optical model potentials are taken to have Woods-Saxon, parity and spin-orbit interactions. The present analysis gives a satisfactory fit to the forward angle data but grossly over estimates the cross-sections in the backward regions. The spin-orbit potential provides the best description of the experimental data and is found to be necessary to account for the large-angle cross sections. The obtained values of the extracted spectroscopic factors are reasonable.

Go to article

Empirical Correlations Of Global Solar Radiation With Meteorological Data For Onne, Nigeria, Louis E. Akpabio, Sunday O. Udo, Sunday E. Etuk Jan 2004

Empirical Correlations Of Global Solar Radiation With Meteorological Data For Onne, Nigeria, Louis E. Akpabio, Sunday O. Udo, Sunday E. Etuk

Turkish Journal of Physics

Multiple linear regression models were developed to estimate the monthly average daily global solar radiation using ten parameters during a period of sixteen years (1984 to 1999) for Onne, Nigeria; the extraterrestrial radiation, average daily temperature, ratio of minimum and maximum daily temperature, relative humidity, ratio of sunshine duration, solar declination, average soil temperature, average pan evaporimeter, average rain fall and average daily dew. Even though up to ten variable correlations has been developed; the results showed that eight variable correlations with the highest value of correlation coefficient R gives the best result when considering the error terms (mean percentage …

Go to article

Electrical Properties Of Hydrogen Transport Vpe Grown N-Cdte Epilayers On Znte/Gaas, Murat Bayhan Jan 2004

Electrical Properties Of Hydrogen Transport Vpe Grown N-Cdte Epilayers On Znte/Gaas, Murat Bayhan

Turkish Journal of Physics

Electrical characterisation of n-CdTe epilayers grown by hydrogen transport vapour phase epitaxy (H_2T-VPE) on insulating ZnTe/(100)GaAs substrates through the temperature dependent Hall measurements is reported. Double-crystal X-ray diffraction assessments indicate the material high crystalline quality. Samples grown at temperatures, T_G < 650 °C were p-type, but appeared to be n-type for the temperatures above T_G > 650 °C. Hall measurements performed on n-type samples of different thicknesses grown at T_G = 764 °C showed room temperature carrier densities in the range of 10^{11}-10^{14} cm^{-3}. The electron density and Hall mobility characteristics may be in principle well explained with a two-level affective model. The model of scattering by lattice and ionised impurity were found to be limiting …

Go to article

Advances In Pattern Recognition Algorithms, Architectures, And Devices, Mohammad S. Alam, Mohammad A. Karim Jan 2004

Advances In Pattern Recognition Algorithms, Architectures, And Devices, Mohammad S. Alam, Mohammad A. Karim

Office of Research Faculty & Staff Publications

Over the last decade, tremendous advances have been made in the general area of pattern recognition techniques, devices, and algorithms. We have had the distinct pleasure of witnessing this remarkable growth as evidenced through their dissemination in the previous Optical Engineering special sections we have jointly edited— January 1998, March 1998, May 2000, and January 2002. Twenty-six papers were finally accepted for this latest special section, encompassing the recent trends and advancements made in many different areas of pattern recognition techniques utilizing algorithms, architectures, implementations, and devices. These techniques include matched spatial filter based recognition, hit-miss transforms, invariant pattern recognition, …

Go to article

Variation Of Chemical Potential Oscillations Of A 2deg In A Quantum Well Under A Magnetic Field For Multiple Sub-Band Occupation As Function Of Temperature And Level-Broadening, Berri̇n Özdemi̇r, Zeki̇ Yarar, Meti̇n Özdemi̇r Jan 2004

Variation Of Chemical Potential Oscillations Of A 2deg In A Quantum Well Under A Magnetic Field For Multiple Sub-Band Occupation As Function Of Temperature And Level-Broadening, Berri̇n Özdemi̇r, Zeki̇ Yarar, Meti̇n Özdemi̇r

Turkish Journal of Physics

We study the variation of chemical potential in a two dimensional electron gas in a uniform magnetic field as a function of temperature and level-broadening parameter. Schrödinger and Poisson equations are solved self-consistently for a two dimensional electron gas formed in a Ga_xAl_{1-x}As/GaAs quantum well, to numerically determine the potential profile, empty or occupied energy sub-bands, the wavefunctions and electron concentrations corresponding to each sub-band at various temperatures. Then assuming that the electron concentration is not altered, the variation of chemical potential with respect to both temperature and energy level-broadening parameter is studied under a uniform and constant magnetic field. …

Go to article

Effect Of Iron Concentrations On Some Physical Properties Of The System Li_{0.5}Fe_{X}Ga_{2.5 - X}O_{4}, Abd El-Raouf Tawfik, N. Tashtoush, O.M. Hemeda Jan 2004

Effect Of Iron Concentrations On Some Physical Properties Of The System Li_{0.5}Fe_{X}Ga_{2.5 - X}O_{4}, Abd El-Raouf Tawfik, N. Tashtoush, O.M. Hemeda

Turkish Journal of Physics

A series of Li_{0.5} Fe_{x} Ga_{2.5 - x} O_{4} systems were prepared for x = 0, 0.25, 0.5, 0.75 and 1 by the general ceramic method. X-ray diffraction showed that all compositions have single phase Spinel cubic structure. The lattice parameter increased with enhancing iron concentration. The thermoelectric coefficient decreased with increasing x, and the majority carriers are holes. The increase of the jump length of hole increased the electrical conductivity. Jump-length increased with iron concentration and the rate of jumping gave rise to the electrical conductivity. The concentration of Fe^{3 +} ions in Lithium gallate is important, for such …

Go to article

Quantum Statistical Entropy Of Sen Black Hole, Zhao Ren, Wu Yueqin, Zhang Lichun Jan 2004

Quantum Statistical Entropy Of Sen Black Hole, Zhao Ren, Wu Yueqin, Zhang Lichun

Turkish Journal of Physics

In this paper, by using quantum statistical methods, we directly obtain the partition function of Bose field and Fermi field on the background of the axisymmetrical Sen black hole. The difficult-to-solve wave equation is avoided. Then via the improved brick-wall method and membrane model, we calculate the entropy of Bose field and Fermi field of the black hole. We find that the entropy of the black hole is proportional to the area of the horizon. In our results, we do not encounter the left out term nor the divergent logarithmic term that appears in the original brick-wall method. The question …

Go to article

E2/M1 Multipole Mixing Ratios Of Transitions In Erbium Isotopes, Harun Reşi̇t Yazar, İhsan Uluer Jan 2004

E2/M1 Multipole Mixing Ratios Of Transitions In Erbium Isotopes, Harun Reşi̇t Yazar, İhsan Uluer

Turkish Journal of Physics

Erbium isotopes (Z = 64) lie in the transitional region that occurs at the middle of the range of deformed nuclei. \gamma -ray E2/M1 mixing ratios for selected transitions in ^{166-168}Er are calculated in the proton-neutron interacting boson approximation(IBA-2). The results obtained for ^{166 -168}Er are reasonably in good agreement with the previous experimental and teoretical values.

Go to article

Charged Particle--Image Interaction Near A Conducting Surface, Ersen Mete, Meti̇n Durgut Jan 2004

Charged Particle--Image Interaction Near A Conducting Surface, Ersen Mete, Meti̇n Durgut

Turkish Journal of Physics

The interaction of a bulk electron with conducting surfaces is studied by means of the Bohm-Pines transformation in the second quantization formalism. The effective interaction potentials are obtained for the case of one plane and two plane configurations in the form of electron-image electron scattering.

Go to article

Large Amplitude Wave Trains In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra Jan 2004

Large Amplitude Wave Trains In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra

Turkish Journal of Physics

Using ground-based neutron monitor data of Deep River, the high amplitude anisotropic wave train events (HAE) in cosmic ray intensity have been investigated during the period 1991--1994. It has been observed that the phase of diurnal anisotropy for majority of HAE cases remains in the same co-rotational direction, whereas for some HAE cases the phase of diurnal anisotropy has shifted to later hours. For the majority of HAE cases the amplitude of semi-diurnal anisotropy remains statistically the same, whereas the phase of semi-diurnal anisotropy for all HAE cases has shifted to later hours. Furthermore, for tri-diurnal anisotropy the phase shifts …

Go to article

Structural And Magnetic Properties Of Co_{0.6}Znn_{0.4}Mn_{X}Fe_{2 - X}O_{4}, O.M. Hemeda Jan 2004

Structural And Magnetic Properties Of Co_{0.6}Znn_{0.4}Mn_{X}Fe_{2 - X}O_{4}, O.M. Hemeda

Turkish Journal of Physics

A series of Co-Zn ferrite samples substituted by Mn were prepared by the usual double sintering ceramic technique. The x-ray diffraction patterns of the samples confirmed the formation of single-phase spinel structure, and x-ray analysis supply data that suggests the cation distribution of the material. The tetrahedral and octahedral radius permits one to calculate the theoretical lattice parameter and the bond lengths Fe-O at A and B sites. The particle size of the given samples was measured from the Scherer equation and a correlation was found between particle size, and structural and magnetic properties. The XRF confirmed the presence of …

Go to article

The Normal And Inverted Meyer-Neldel Rule In The Ac Conductivity, Fouad Abdel-Wahab Jan 2004

The Normal And Inverted Meyer-Neldel Rule In The Ac Conductivity, Fouad Abdel-Wahab

Turkish Journal of Physics

Recently, a new approach has been proposed for the correlated barrier hopping (CBH) model where the ac relaxation time is thought to obey the Meyer-Neldel (MN) rule. This approach gives quantitative agreement with some reliable published experimental data. We report on an experiment involving the characterization of the ac conductivity of Se-Te thin films over a wide range of frequencies and temperatures, carried out in order to confirm applicability of the MN rule to the ac conductivity. In addition to the normal MN rule, the inverted MN rule was observed.

Go to article

Design And Preparation Of Antireflection And Reflection Optical Coatings, Özlem Duyar, H. Zafer Durusoy Jan 2004

Design And Preparation Of Antireflection And Reflection Optical Coatings, Özlem Duyar, H. Zafer Durusoy

Turkish Journal of Physics

In this study, reflective and antireflective coatings were designed and simulated. Optical transmission and reflection values were deduced with a matrix formulation via a personal computer. It was found that the number of layers affects the optical performance. The width of the high-reflectance region in the reflectance curves decreases, while its height increases with the increasing number of layers for the reflective coating design. The antireflection coatings transmit about 99.89% in a broad high-pass band at the central wavelength of \lambda_{0} = 450 nm. In addition, simulated Fabry-Perot filters result in a single sharp transmittance peak at the desired central …

Go to article

The Riemann Zeta Function Applied On Glassy Systems And Neural Networks, Viorel L. Cartas Jan 2004

The Riemann Zeta Function Applied On Glassy Systems And Neural Networks, Viorel L. Cartas

Turkish Journal of Physics

Glassy systems and Neural networks share a simple model of study: the model of a set of N non interacting harmonic oscillators with energy. In this paper the author tries to describe these complex systems in order to find the energy involved. The mathematical method used is described in detail.

Go to article

Exceptionaly Low Amplitude Anisotropic Wave Train Events In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra Jan 2004

Exceptionaly Low Amplitude Anisotropic Wave Train Events In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra

Turkish Journal of Physics

The unusually low amplitude anisotropic wave train events (LAEs) in cosmic ray intensity using the ground-based Deep River neutron monitor data has been studied during the period 1991--94. It has been observed that the phase of the diurnal anisotropy for majority of the LAE events remains in the corotational direction. However, for some of the LAE events the phase of the diurnal anisotropy shifts towards earlier hours. On the other hand, the amplitude of the semi-diurnal anisotropy remains statistically the same whereas, phase shift towards later hours; similar trend has also been found in case of tri-diurnal anisotropy. The interplanetary …

Go to article

On Hamiltonian Formulation Of Non-Conservative Systems, Eqab M. Rabei, Tareq S. Alhalholy, A. A. Taani Jan 2004

On Hamiltonian Formulation Of Non-Conservative Systems, Eqab M. Rabei, Tareq S. Alhalholy, A. A. Taani

Turkish Journal of Physics

Fractional derivatives are used to construct the Lagrangian and the Hamiltonian formulation for non-conservative systems. To clarify the theory of Riewe two interesting examples are given. The potentials are obtained using the Laplace transform operator for fractional derivatives and the Lagrangian and Hamiltonian formulations are constructed for the two systems. Besides, it is shown that the Hamilton equations of motion are in agreement with the Euler-Lagrange equations for these systems.

Go to article

Self Ionization Probabilities Following De-Excitation Decay Of K-Shell Vacancy In Atoms Z = 10--80, Adel M. El-Shemi Jan 2004

Self Ionization Probabilities Following De-Excitation Decay Of K-Shell Vacancy In Atoms Z = 10--80, Adel M. El-Shemi

Turkish Journal of Physics

The average number of ejected electrons and the probability of ion charge state distributions following K-shell ionization in atoms from Z = 10 to Z = 80 were calculated. Monte Carlo simulation technique was used to simulate all possible pathways of radiative and non-radiative transitions to fill the inner-shell ionization in excited atoms. The radiative and non-radiative branching ratios were calculated from Multiconfiguration Dirac-Fock (MCDF) and Dirac-Fock-Slater (DFS) wave functions. The average number of ejected electrons in atoms with Z = 10 is about two, because the non-radiative transitions exceed radiative transitions by 98\%. The mean number of ejected electrons …

Go to article

Comparative Study Of First Two Harmonics In Cosmic Ray Intensity For The Period 1964-95, Rekha Agarwal Mishra, Rajesh K. Mishra Jan 2004

Comparative Study Of First Two Harmonics In Cosmic Ray Intensity For The Period 1964-95, Rekha Agarwal Mishra, Rajesh K. Mishra

Turkish Journal of Physics

The Deep River neutron monitor data has been harmonically analyzed for the period 1964--95 covering three solar cycles 20, 21 and 22, looking for a long term trend of the diurnal and semi-diurnal anisotropies of cosmic ray intensity on geomagnetically 60 quiet days. The amplitude of both the harmonics remains statistically constant during 1964-70. The amplitudes of the first harmonic is found to be low during 1965, 1967, 1976-77, 1986-87, 1991, 1993 and 1995. The amplitude of diurnal anisotropy acquired exceptionally large values in 1985, whereas semi-diurnal anisotropy acquired large values in 1974-75 and in 1984, which coincided with epochs …

Go to article

Determination Of The Rotational Constant A_0 And The Bending Angle Cnc For Ch_3 Nc And Ch_3 ^{15}Nc Molecules, Mohammad Al-Share Jan 2004

Determination Of The Rotational Constant A_0 And The Bending Angle Cnc For Ch_3 Nc And Ch_3 ^{15}Nc Molecules, Mohammad Al-Share

Turkish Journal of Physics

The rotational constant A_0 for the ground state of CH_3 NC and CH_3 ^{15}NC isotopomers is calculated using a technique which was used earlier for CH_3CCH [9], CH_3CN [10] and SiH_3CCH [11]. This technique is based on calculating the moment of inertia tensors in the bent configuration due to the \nu_8 vibrational state, which is associated with the CNC bending vibration. These values of the moments of inertia are fitted with the values calculated from the rotational constant B_V, found experimentally by measuring the rotational frequencies in the microwave and infrared regions. From the fitting, the rotational constant A_0, the …

Go to article

A Novel Radiative Substrate Heater, Abdullah Ceylan, Erdal Kaynak, Şadan Özcan, Tezer Firat Jan 2004

A Novel Radiative Substrate Heater, Abdullah Ceylan, Erdal Kaynak, Şadan Özcan, Tezer Firat

Turkish Journal of Physics

In this work, we have developed a new low cost radiative substrate heater for deposition of high-T_c superconducting thin films. It has all the features required for the preparation of high quality superconducting thin films. It is possible to reach ~ 800 °C substrate temperature with it by using only one 250 W halogen projector bulb.

Go to article

Effect Of Development Time On Polymer Phase Separation In A Pmma Resist, Mohammad Naeem Khalid, Shazia Yasin, Mohammad Riaz Khan Jan 2004

Effect Of Development Time On Polymer Phase Separation In A Pmma Resist, Mohammad Naeem Khalid, Shazia Yasin, Mohammad Riaz Khan

Turkish Journal of Physics

Developer composition type and development technique are known to influence surface and edge roughness in polymethylemethacrylate (PMMA); and it is during development, we believe, that the result is most influenced by the phase separation into polymer-rich and polymer-poor regions. This polymer phase separation is more prominent in a weaker developer and low temperature. In this paper, we investigate the effect of development time on the extent of polymer phase separation in an exposed PMMA developed in a standard developer i.e. 1:3 MIBK:IPA at 20 °C and rinsed in pure IPA for 30 sec. The polymer phase separation is found to …

Go to article

The Zero Position Of The Forward-Backward Asymmetry In The B \Rightarrow K\Ell^+\Ell^- Decay With New Physics Effects, Altuğ Arda Jan 2004

The Zero Position Of The Forward-Backward Asymmetry In The B \Rightarrow K\Ell^+\Ell^- Decay With New Physics Effects, Altuğ Arda

Turkish Journal of Physics

Using the most general model-independent effective Hamiltonian comprising local four-Fermi operators (scalar, vector, and tensor operators), we study the sensitivity of the zero position of the lepton asymmetry to the new operators beyond the Standard Model (SM) in the B \rightarrow K\ell^+\ell^- decay. It is found that among all operators, only the scalar and tensor operators contribute to the forward-backward asymmetry, in which case the forward-backward asymmetry has a non-vanishing value.

Go to article

Physical Characteristics Of Polymer Magnetic Microspheres, Rasim A. Ali-Zade Jan 2004

Physical Characteristics Of Polymer Magnetic Microspheres, Rasim A. Ali-Zade

Turkish Journal of Physics

In this study the structure and the magnetic properties of polymer microspheres, filled with magnetite nanoparticles are investigated. Average particle size of magnetite nanoparticles before and after being introduced into polymer microspheres, and the distance between nanoparticles in the polymer microspheres, are measured. Magnetization curve of polymer magnetic microspheres (PMMS) is determined. The magnetic susceptibility of PMMS with various diameters, and the dependence of PMMS magnetic susceptibility on diameter are determined. Magnetization occurs due to the orientation of PMMS as a magnetic moment. The total magnetic moment of PMMS is the sum of magnetic moments of PMMS sections which consist …

Go to article

Simulation Of Millimeter-Wave Gunn Oscillations In Gallium Nitride, Cem Sevi̇k, Ceyhun Bulutay Jan 2004

Simulation Of Millimeter-Wave Gunn Oscillations In Gallium Nitride, Cem Sevi̇k, Ceyhun Bulutay

Turkish Journal of Physics

High field transport in wide bandgap semiconductors like GaN is of great technological importance. The negative differential mobility regime at high fields, under suitable conditions, can lead to millimeter-wave Gunn oscillations. Using extensive simulation based an ensemble Monte Carlo technique, the prospects of GaN Gunn diodes are theoretically investigated. The possibility of operating these Gunn diodes at their higher harmonic modes are explored. The main finding of this research is that the carrier dynamics in GaN can be tailored by an optimum choice of doping profile, temperature and bias conditions so that the efficiency of higher harmonic Gunn oscillations can …

Go to article

Structural Characterization And Magnetization Of Mg_{0.5}Cu_{0.5}Y_{X}Fe_{2-X}O_4 Ferrites, Mansour Al-Haj Jan 2004

Structural Characterization And Magnetization Of Mg_{0.5}Cu_{0.5}Y_{X}Fe_{2-X}O_4 Ferrites, Mansour Al-Haj

Turkish Journal of Physics

Mg_{0.5}Cu_{0.5}Y_xFe_{2-x}O_4 ferrites were prepared by the solid state reaction method and were characterized by X-ray diffraction and magnetization measurements. A single spinel phase was obtained in the range 0 \le x \le 0.08. The lattice parameter was found to increase with the increase of x except at x = 0.08, which may indicate a distortion in the spinel lattice. The saturation magnetization was found to decrease with increasing x due to replacement of the magnetic Fe^{3+} ions by the nonmagnetic Y^{3+} ions.

Go to article

First Prev Next Last