Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
-
- Decoherence (5)
- Copper (4)
- Synthesis (4)
- Adsorption (3)
- Differential pulse polarography (3)
-
- Earthquake (3)
- Lamiaceae (3)
- Oxidation (3)
- Purification (3)
- Spectrophotometry (3)
- Activation energy (2)
- Analgesic (2)
- Anti-inflammatory (2)
- Antibacterial activity (2)
- Antifungal activity (2)
- Archaeoseismology (2)
- Bentonite (2)
- Bromination (2)
- Determination (2)
- Dynamic behavior (2)
- Enrichment (2)
- Faulting (2)
- Flame atomic absorption spectrometry (2)
- Glass structure (2)
- Interference in nanostructures (2)
- Kinetics (2)
- Manganese (2)
- Phlomis samia (2)
- Resonant transmission (2)
- Rough kernels (2)
Articles 1 - 30 of 212
Full-Text Articles in Physical Sciences and Mathematics
The Motion Of Cosmic Strings In The Schwarzschild Black Hole Spacetime, Sergey Roshchupkin, Yevgeniy Zinchenko
The Motion Of Cosmic Strings In The Schwarzschild Black Hole Spacetime, Sergey Roshchupkin, Yevgeniy Zinchenko
Turkish Journal of Physics
We study the classical dynamics of a bosonic string in the Schwarzschild spacetime using a perturbative scheme which is based on the assumption of a small value of a rescaled string tension parameter. The proposed approximation selfconsistently describes the string dynamics on the scale of large values for the worldsheet time in a fixed gauge.
Theory Of Antisymmetric Tensor Fields, Valeri Dvoeglazov
Theory Of Antisymmetric Tensor Fields, Valeri Dvoeglazov
Turkish Journal of Physics
It has long been claimed that the antisymmetric tensor field of the second rank is pure longitudinal after quantization. In my opinion, such a situation is quite unacceptable. I repeat the well-known procedure of the derivation of the set of Proca equations. It is shown that it can be written in various forms. Furthermore, on the basis of the Lagrangian formalism I calculate dynamical invariants (including the Pauli-Lubanski vector of relativistic spin for this field). Even on the classical level, the Pauli-Lubanski vector can be equal to zero after applications of well-known constraints. The importance of the normalization is pointed …
Multiply Charged Ions Produced After Deexcitation Processes For Important Elements In Astrophysics, Adel M. El-Shime, Adel A. Ghoneim, Yehia A. Lotfy
Multiply Charged Ions Produced After Deexcitation Processes For Important Elements In Astrophysics, Adel M. El-Shime, Adel A. Ghoneim, Yehia A. Lotfy
Turkish Journal of Physics
Selection random number method (Monte Carlo technique) is used to calculate the ion charge state distributions (CSD) and mean ion charge \bar{q} after K-, L_{I}, L_{III}- and M_{I}- shell ionization in neutral atoms and their q-fold ground state ions (q = 0 to 10) from C to Fe elements. Atomic data for radiative and non-radiative transitions and electron shake off process, which is used in the modeling vacancy cascade program, are computed with relativistic wave functions. Use of atomic data is important to accurately model vacancy cascades. To enhance the agreement between calculated and experimental values, the electron shake-off processes …
Modeling Of Infrared Radiation For All Skies From Easy-To-Measure Meteorological Parameters At Tropical Location: Ilorin, Nigeria, Sunday O. Udo
Modeling Of Infrared Radiation For All Skies From Easy-To-Measure Meteorological Parameters At Tropical Location: Ilorin, Nigeria, Sunday O. Udo
Turkish Journal of Physics
Downward infrared radiation (L) and some easy-to-measure meteorological variables (relative humidity, clearness index and vapour pressure) were collected for a period of two years at Ilorin. Downward infrared radiation data were obtained using a pyrgeometer (Eppley-PIR), while data for relative humidity and vapour pressure for Ilorin were obtained from the Nigerian Meteorological Services, Lagos. Based on these data, using statistical regression analysis, empirical models (seven one-variable and nine two-variable) for predicting daily mean infrared radiation, from both clear and cloudy skies, were tested. Their advantage is that they only make use of easily measured meteorological parameters. The best one-variable model …
Operation Parameters Of The Thermionic Vacuum Arc Discharge, Tamer Akan
Operation Parameters Of The Thermionic Vacuum Arc Discharge, Tamer Akan
Turkish Journal of Physics
The thermionic vacuum arc (TVA) discharge with evaporating anodes employing directly heated thermionic cathodes is investigated. The TVA discharge generates a pure, gas-free metal vapor plasma containing ions with a directed energy. The TVA is strongly controlled by the cathodic electron beam and there is a quite good stability of important operation parameters like the arc voltage and the arc current.
Development Of Double Discharge Pulsed Electron Beam Generator And Its Preliminary Applications In Material Processing, Hi̇lal Göktaş, Gulay Oke, Mircea Udrea
Development Of Double Discharge Pulsed Electron Beam Generator And Its Preliminary Applications In Material Processing, Hi̇lal Göktaş, Gulay Oke, Mircea Udrea
Turkish Journal of Physics
This article presents the construction of a fast, intense electron beam generator, several of its operational properties and its preliminary applications. A fast filamentary discharge produced in a tube filled with Argon gas at pressure of about 0.1 torr. An electron beam is obtained with a current intensity of about 0.6 A for a 25 ns duration. The length of the filamentary discharge and the behavior of the beam in the magnetic field are examined. The interaction of the beam with different targets was investigated by Scanning Electron Microscope. It is also demonstrated that the device can be used to …
The Influence Of Ge Content And Annealing Temperature On The D.C And A.C Conductivity Of Ge_{X}Se_{1 - X} Thin Films, Maysoon Faisal Alias, M. N. Makadsi, Z. M. Al-Ajeli
The Influence Of Ge Content And Annealing Temperature On The D.C And A.C Conductivity Of Ge_{X}Se_{1 - X} Thin Films, Maysoon Faisal Alias, M. N. Makadsi, Z. M. Al-Ajeli
Turkish Journal of Physics
Various samples of Ge_{x}Se_{1 - x} system have been prepared for x = 0.05, 0.15& 0.25 in an evacuated quartz tube. Thin films of Ge_{x}Se_{1 - x} film have been prepared via a thermal evaporation method with 350 \pm 5 nm thickness and rate deposition 6 nm/s. The alloy structure and thin films have been examined by X-ray diffraction (XRD). Atomic absorption spectroscopy (AAS) was used to examine the concentration of the composite elements (Ge and Se). The d.c and a.c conductivity of Ge_{x}Se_{1 - x} thin film have been studied as a function of Ge content x and annealing …
Microwave Signal Attenuation In Harmattan Weather Along Calabar-Akampkpa Line-Of-Sight Link, O. E. Eyo, A. I. Menkiti, Sunday O. Udo
Microwave Signal Attenuation In Harmattan Weather Along Calabar-Akampkpa Line-Of-Sight Link, O. E. Eyo, A. I. Menkiti, Sunday O. Udo
Turkish Journal of Physics
Line-of-sight (LOS) attenuation at 6.44GHz was measured at Calabar (4° 58' N, 8° 17' E) for ten months (Aug '93-May '94) using the Nigerian Telecommunications radio signal. The measurement was made with the intent of highlighting microwave signal attenuation in Harmattan weather conditions. The results are presented in terms of mean signal level and fog attenuation, fade rate distribution, fade depth distribution and scintillation index. The observed attenuation values due to Harmattan (fog) and the calculated (using Altshuler's model) are in fairly good agreement. Also, the statistics of fade distribution show fast fading of longer duration of the order of …
Relationship Between Global Solar Radiation And Sunshine Duration For Onne, Nigeria, Louis E. Akpabio, Sunday E. Etuk
Relationship Between Global Solar Radiation And Sunshine Duration For Onne, Nigeria, Louis E. Akpabio, Sunday E. Etuk
Turkish Journal of Physics
Measurements of global solar radiation and sunshine duration data during the period from 1984 to 1999 at Onne (within the rainforest climatic zone of southern Nigeria) were used to establish an Angstrom-type correlation equation. Five other commonly used correlations between global solar radiation and sunshine duration were also used to estimate global solar irradiation for Onne and their results are compared with our model. A good agreement (greater than 90% in most cases) was observed between the measured and the predicted values of our model.
Initial Electron Beam Polarization Measurement In E-\Gamma Collisions, Gökhan Ünel
Initial Electron Beam Polarization Measurement In E-\Gamma Collisions, Gökhan Ünel
Turkish Journal of Physics
The future high energy e e colliders, together with the complementary \gamma \gamma option, will offer possibilities for both discovery and precision physics. The uncertainty on the initial beam polarizations contributes to the systematic errors in each case. Therefore, it is crucial to obtain the precise beam polarizations by independent measurements. The e \gamma \rightarrow \nu W process in the e \gamma mode can be used to experimentally determine the polarization of the initial e beam. This note addresses the feasibility of making such a measurement with a relative statistical error of one percent. Generator and detector level MC tools …
Nuclear Matrix Elements Of Double Beta Decay In Deformed Nuclei, C. Selam, Atalay Küçükbursa, H. Bi̇rcan, H. A. Aygör, T. Babacan, İ. Maraş, A. Kökçe
Nuclear Matrix Elements Of Double Beta Decay In Deformed Nuclei, C. Selam, Atalay Küçükbursa, H. Bi̇rcan, H. A. Aygör, T. Babacan, İ. Maraş, A. Kökçe
Turkish Journal of Physics
Nuclear matrix elements (M_{GT}) for two-neutrino double beta transitions of selected nuclei were calculated via a QRPA approach by considering the charge-exchange spin-spin interactions in the particle-hole channel among nucleons. Calculations were performed for both spherical and deformed cases of nuclei. As a result of these calculations, it has been seen that, although the value of the nuclear matrix elements in deformation case are 2-4 times smaller when compared with that of the spherical case, it is still 2-8 times greater than the experimental values.
High-Pressure Phase Transition In Some Alkali Halides Using Interatomic Potential Model, Harun Reşi̇t Yazar
High-Pressure Phase Transition In Some Alkali Halides Using Interatomic Potential Model, Harun Reşi̇t Yazar
Turkish Journal of Physics
We have predicted the phase transition pressure in some alkali halides NaCl and KCl using an interatomic potential approach based on a rigid ion model. We have obtained phase transition pressures 28.69 and 2.4 GPa, respectively, and are in close agreement with their corresponding experimental transition pressures 29.0 and 2.0 GPa. This approach is promising with respect to the prediction of the phase transition pressures of other alkali halides.
Clebsch-Gordan Equalities That Imply The Vanishing Of Particular 6j Symbols, Harry A. Mavromatis
Clebsch-Gordan Equalities That Imply The Vanishing Of Particular 6j Symbols, Harry A. Mavromatis
Turkish Journal of Physics
Three Clebsch-Gordan equalities and three individual Clebsh-Gordan relations are obtained by studying the non-accidental vanishing of certain 6j symbols.
Characterization Of In_{4}Te_{3} Single Crystals, M. Dongol, M. M. Nassary, M. K. Gerges, M. A. Sebag
Characterization Of In_{4}Te_{3} Single Crystals, M. Dongol, M. M. Nassary, M. K. Gerges, M. A. Sebag
Turkish Journal of Physics
Single crystals of In_{4}Te_{3} grown by modified Bridgman technique were characterized by measurement of the Hall coefficient, electrical conductivity and Seebeck coefficient, in the temperature range 200-500 K. The investigated sample was found to be of P-type conductivity.R_{H} at room temperature was 3.1 \times 10^{14} cm^{3}/coul and the carrier concentration was evaluated as 2.007 \times 10^{14} cm^{3}. Energy gap \Delta E_{g} and ionization energy \Delta E_{a} were estimated as 0.28 eV and 0.12 eV, respectively, and the diffusion coefficient, the diffusion length, the mean free time between collision and the effective mass of carriers were evaluated. The variation of the …
Study Of The Structure And Some Physical Properties Of Sodium-Boro-Phosphate Glasses Containing Antimony And Iron Oxides, Karam Abdel-Aati̇ Ali, Ahmet Gamal El-Din Mostafa
Study Of The Structure And Some Physical Properties Of Sodium-Boro-Phosphate Glasses Containing Antimony And Iron Oxides, Karam Abdel-Aati̇ Ali, Ahmet Gamal El-Din Mostafa
Turkish Journal of Physics
Boro-phosphate glasses containing transition metal oxides are of special interest. Hence, some sodium-Boro-phosphate glasses containing iron and antimony oxides were prepared and investigated. The structural investigation indicated the presence of different borate groups as well as tetragonal phosphate units. Most of the iron cations were found to occupy the low spin Fe^{3 +} in the tetrahedral coordination state. It was observed that some antimony act as network former cations and some others act as bridges between any two adjacent polyhedra. At high antimony oxide content, the formation of some Sb-Fe bonds was also detected. The magnetic susceptibility measurements showed a …
Studies On Some Lithium-Borate Glasses Containing Iron And Copper, G. A. Yahya
Studies On Some Lithium-Borate Glasses Containing Iron And Copper, G. A. Yahya
Turkish Journal of Physics
A lithium-borate-glass system containing iron and copper cations has been thoroughly investigated, in order to obtain information about the structural role of both the iron and copper in such glass hosts. The amorphous phase of the prepared glass samples was confirmed from their X-ray diffraction. From the infrared spectra it was concluded that the glass networks are highly deformed and boron appeared in both tri- and tetra-hedral coordination states as well as in some ring structure. As copper was introduced, replacing lithium, it acts as a network modifier only while the iron acts as network former (FeO_4). The molar magnetic …
Change Of Birefringence In Dye-Doped Nematic Liquid Crystals Under Laser Illumination, S. Eren San, Oğuz Köysal, Serhat Özder, F. Necati̇ Ecevi̇t
Change Of Birefringence In Dye-Doped Nematic Liquid Crystals Under Laser Illumination, S. Eren San, Oğuz Köysal, Serhat Özder, F. Necati̇ Ecevi̇t
Turkish Journal of Physics
Birefringence property of E7 nematic liquid crystal is investigated via voltage dependent transmittance spectrums. Measurements are performed at wavelength 632.8 nm, which is the absorbance peak of our sample including anthraquinone derivative Disperse Blue 14. Results of dye-doped samples are compared with those undoped for dark and laser illuminated cases. It was observed that birefringence is dependent on laser illumination for dye-doped samples, up to a threshold voltage after which it is constant.
Decoherence In Two Coupled Qubits, Kristian Rabenstein, Dmitri V. Averin
Decoherence In Two Coupled Qubits, Kristian Rabenstein, Dmitri V. Averin
Turkish Journal of Physics
We have developed quantitative description of quantum coherent oscillations in the system of two coupled qubits in the presence of weak decoherence that in general can be correlated between the two qubits. It is shown that in the experimentally realized scheme of excitation of the oscillations, their waveform is not very sensitive to the magnitude of decoherence correlations. Modification of this scheme into potentially useful probe of the degree of decoherence correlations at the two qubits is suggested.
Adiabatic Quantum Pumping Of Coherent Electrons, Ora Entin-Wohlman, Amnon Aharony, Vyacheslavs Kashcheyevs
Adiabatic Quantum Pumping Of Coherent Electrons, Ora Entin-Wohlman, Amnon Aharony, Vyacheslavs Kashcheyevs
Turkish Journal of Physics
We review recent theoretical calculations of charge transfer through mesoscopic devices in response to slowly-oscillating, spatially-confined, potentials. The discussion is restricted to non-interacting electrons, and emphasizes the role of quantum interference and resonant transmission in producing almost integer values (in units of the electronic charge e) of the charge transmitted per cycle, Q. The expression for the pumped charge is derived from a systematic expansion of the system scattering states in terms of the temporal derivatives of the instantaneous solutions. This yields the effect of the modulating potential on the Landauer formula for the conductance in response to a constant …
Quantum Computing With Electrons On Liquid Helium, İsmai̇l Karakurt
Quantum Computing With Electrons On Liquid Helium, İsmai̇l Karakurt
Turkish Journal of Physics
A quantum computer based on electrons floating over liquid helium is described. Each qubit is made of combinations of ground and first excited states of an electron trapped over micro-electrodes just below the helium surface. We describe mechanisms for preparing the initial state of the qubit, operations with the qubits, and a proposed readout. This system is, in principle, capable of \sim 10^4 operations in a decoherence time, the time in which the wave function collapses.
Au Nanoparticle Clusters: A New System To Model Hopping Conduction, Ç. Kurdak, J. Kim, L. A. Farina, K. M. Lewis, X. Bai, M. P. Rowe, A. J. Matzger
Au Nanoparticle Clusters: A New System To Model Hopping Conduction, Ç. Kurdak, J. Kim, L. A. Farina, K. M. Lewis, X. Bai, M. P. Rowe, A. J. Matzger
Turkish Journal of Physics
We study electrical transport through self-assembled Au nanoparticle clusters which can be viewed as a new model system to study hopping transport. The physics of such systems is governed by two parameters: the charging energy and tunnel coupling between the particles. The charging energy is determined by the size of the nanoparticles. When the diameter of the nanoparticles is less than 4-5 nm the charging energy is large enough that Coulomb blockade effects were observed in electrical transport even at room temperature. The magnitude of the tunnel coupling between the particles was determined by the thiol coating used. To study …
Quantum State Generation And Entanglement Manipulation Using Linear Optics, Şahi̇n Kaya Özdemi̇r, Takashi Yamamoto, Masato Koashi, Nobuyuki Imoto
Quantum State Generation And Entanglement Manipulation Using Linear Optics, Şahi̇n Kaya Özdemi̇r, Takashi Yamamoto, Masato Koashi, Nobuyuki Imoto
Turkish Journal of Physics
Quantum information processing (QIP) requires unitary operations, measurements and synthesis, manipulation and characterization of arbitrary quantum states. Linear optics provides efficient tools for these purposes. In this review paper, we introduce the elements of linear optics toolbox, and briefly discuss some experimental and theoretical investigations using this toolbox. Our main focus will be the qubit state generation and entanglement extraction using linear optics toolbox.
Studies On The Opto-Electronic Constants Of Alkali-Halide Crystals, Mahmoud A. Salem
Studies On The Opto-Electronic Constants Of Alkali-Halide Crystals, Mahmoud A. Salem
Turkish Journal of Physics
In this presentation, the correlation between refractive index n of alkali-halide crystals and both energy band gap E_{g} and Pauling's electronegativity difference \Delta x have been studied. The following relations are proposed for estimating the refractive index n: n^2 + C = A / E_{g} ^{1 / 2} and n^2 + C = E / (\Delta x)^{0.425}, where A, C and E are numerical constants. In addition, an interrelation between the energy band gap E_{g} and electronegativity difference \Delta x has been also proposed. The proposed relation is E_g = 4.45 (\Delta x)^{0.85}. The estimated values of the refractive index …
Network Traffic Properties Of Bimodal Multicast Protocol, Öznur Özkasap, Mi̇ne Çağlar
Network Traffic Properties Of Bimodal Multicast Protocol, Öznur Özkasap, Mi̇ne Çağlar
Turkish Journal of Electrical Engineering and Computer Sciences
The popularity of large-scale distributed applications, such as videoconferencing, multimedia dissemination, electronic stock exchange and distributed cooperative work, has grown with the availability of high-speed networks and the expansion of the Internet. The key property of this type of applications is the need to distribute data among multiple participants together with an application-specific quality of service needs. This fact makes scalable multicast protocols an essential underlying communication structure. Although there exist several studies investigating the traffic characteristics of unicast communication, multicast traffic has not been examined extensively in previous studies. It is well known that the aggregate traffic properties of …
New Approaches For On-Line Tuning Of The Linear Sliding Surface Slope In Sliding Mode Controllers, Sezai̇ Tokat, İbrahi̇m Eksi̇n, Müjde Güzelkaya
New Approaches For On-Line Tuning Of The Linear Sliding Surface Slope In Sliding Mode Controllers, Sezai̇ Tokat, İbrahi̇m Eksi̇n, Müjde Güzelkaya
Turkish Journal of Electrical Engineering and Computer Sciences
The main objective of this study is to propose new approaches for on-line tuning of the linear sliding surface slope in sliding mode controllers. The new approaches are developed for a class of second order systems on new coordinate axes, one of which is the classical sliding surface and the other one is naturally chosen to be orthogonal to it. The control input of the sliding mode control law is then modified accordingly by applying the Lyapunov stability condition. The adjustment of the linear sliding surface slope defined in the new coordinate axes is achieved by tuning a new parameter …
Zero-Crossing Based Demodulation Of Minimum Shift Keying, Mi̇ne Kalkan, Feza Keresteci̇oğlu
Zero-Crossing Based Demodulation Of Minimum Shift Keying, Mi̇ne Kalkan, Feza Keresteci̇oğlu
Turkish Journal of Electrical Engineering and Computer Sciences
Minimum shift keying (MSK) modulation has features such as constant envelope, compact spectrum and good error performance, which are all desirable in many digital applications including mobile radio. Numerous receiver structures to demodulate MSK have been suggested, such as correlation receivers, differential detectors and frequency discriminators. MSK is a form of biphase keying and can be detected by a zero-crossing based phase demodulator which gives near optimum performance. In this paper, the bit error performance of a zero-crossing based coherent MSK demodulator is theoretically investigated and a closed-form expression for the bit error rate is derived. The results indicate that …
Music, Cbf And Differential Algebraic Constant Modulus Algorithms For Direction Of Arrival Estimation In Passive Coherent Locators, Ahmet Özçeti̇n
Music, Cbf And Differential Algebraic Constant Modulus Algorithms For Direction Of Arrival Estimation In Passive Coherent Locators, Ahmet Özçeti̇n
Turkish Journal of Electrical Engineering and Computer Sciences
In passive coherent locators (PCL) systems, noise and the precision of direction of arrival (DOA) estimation are key issues. This paper addresses the implementation of high-resolution DOA estimation methods, in particular the multiple signal classification (MUSIC) algorithm, the conventional beam forming (CBF) algorithm, and the algebraic constant modulus algorithm (ACMA). The goal is to compare the ACMA to the MUSIC and CBF algorithms for application to PCL. The results and analysis presented here support the use of constant modulus information, where available, as an important addition to DOA estimation. The ACMA offers many simple solutions to noise and separation related …
A Digitally Controlled Drive System For Travelling-Wave Ultrasonic Motor, Güngör Bal
A Digitally Controlled Drive System For Travelling-Wave Ultrasonic Motor, Güngör Bal
Turkish Journal of Electrical Engineering and Computer Sciences
A digitally controlled drive system was implemented in this study to control the speed and direction of a travelling-wave ultrasonic motor. The drive system, based on a 2-phase voltage-fed high-frequency serial-resonant inverter, uses the mechanical resonant frequency of an ultrasonic motor. A TMS320F243 digital signal processor was used to control an ultrasonic motor drive system. The speed control of the ultrasonic motor was achieved with a driving frequency in the 41.3-43.3 kHz frequency range. The feasible evaluations of the proposed drive and control system were tested by experiments. Experimental results demonstrated that the proposed drive and control system is flexible …
Parametrically Tunable Audio Shelving And Equalizing Ladder Wave Digital Filters, S. A. Samad
Parametrically Tunable Audio Shelving And Equalizing Ladder Wave Digital Filters, S. A. Samad
Turkish Journal of Electrical Engineering and Computer Sciences
Parametrically tunable audio equalizers are conventionally realized using allpass digital filter networks. They consist of first-order shelving filters and second-order equalizing filters. In this paper, ladder wave digital filters (WDFs) with parametrically tunable coefficients are proposed as shelving and equalizing filters. Similar to the allpass realization, the transfer function power complementary property of WDFs is used to obtain efficient shelving and equalizing filters. However, unlike the allpass structures, the transfer function and the tunable parameters of the ladder WDF are derived from the analog filter equivalent of the digital shelving and equalizing filters. For the shelving WDF, the cut-off frequency …
A New Simulator For Hvdc/Ac Systems-Part I, Baktiar Zangeneh, Abbas Shoulaie
A New Simulator For Hvdc/Ac Systems-Part I, Baktiar Zangeneh, Abbas Shoulaie
Turkish Journal of Electrical Engineering and Computer Sciences
A simulator with optimal step time (SOST) has been designed to investigate Large HVdc/ac systems. The adequacy and robustness of the simulator will be demonstrated by showing some important applications relevant to operation, operational planning and medium-term planing. Some of the features of our SOST simulator are optimal step time algorithm, interpolation, chatter removal, MATLAB interface, unlimited size of ac system, and Farsi command that help model complex power electronic circuits, provide fast and accurate results. On account of its reduced calculation effort and deterministic execution time, optimal-step simulation is a prerequisite for real-time performance. However, when simulating electromagnetic-transients behavior, …