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Sphere-to-Plane Electrodes Configuration of Positive and Negative Plasma Corona Discharge
Sabah I. Wais,
Dunia D. Giliyana
Issue:
Volume 2, Issue 2, March 2013
Pages:
46-52
Abstract: An experimental investigation has been carried out with sphere-to-plane geometrical electrodes for pos-itive and negative corona discharge at atmospheric pressure and different inter-electrode separation. The experimental results have been compared particularly with those refer to point-to-plane and point-to-ring geometriesand a similar common feature has been provided. The current and voltage data was subjected to the relation of Townsend and Ferreira and showed one an upward curvature at low applied voltage (low field region) and then a linear behavior was found in high field region. This means that all acquired current-voltage data for both positive and negative coronas confirm Townsend relation at the inter-electrode distance used in this work. The extrapolated corona inception voltage was followed a non-linear tend with electrode gap distance S. The extrapolated potential Vo for positive corona was more sensitive on the distance S than that of negative corona. The dimensional constants A and K were found to be proportional inversely to the electrode gap distance by different power exponent. The ratios between the dimensional constants A and K for positive and negative corona approached a constant value at gap distance (S 2.5 cm).
Abstract: An experimental investigation has been carried out with sphere-to-plane geometrical electrodes for pos-itive and negative corona discharge at atmospheric pressure and different inter-electrode separation. The experimental results have been compared particularly with those refer to point-to-plane and point-to-ring geometriesand a similar common feat...
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Metastable Bound State of Likely Charged Classic Coulomb Particles
Alexander E. Dubinov,
Ilya N. Kitayev
Issue:
Volume 2, Issue 2, March 2013
Pages:
53-57
Abstract: When the classical charged particle is scattered on the likely charged target particle, executing the rapid finite motion, a metastable bound state of the incident particle and the target particle may occur. This type of behavior differs dramatically from the Rutherford scattering.
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Effective Temperature of the Sun Based on Log Periodic Dipole Antenna Performance In The Range From 45 MHz to 870 MHz
Z. S. Hamidi,
S. H. Chumiran,
Z. S. Hamidi,
N. N. M. Shariff,
Z. A. Ibrahim,
A. Mohamad
Issue:
Volume 2, Issue 2, March 2013
Pages:
58-60
Abstract: The Log Periodic Dipole Antenna (LPDA) performance of solar burst monitoring in the range of (45 -870) MHz is presented. This project is under the International Space Weather Initiative (ISWI) program in order to observe the solar activities within 12 hours per day. At the first stage, we make an effort by constructing LPDA that suitable with the criteria, specification and practical enough with 5.45 meter boom length size of the antenna. The rods then were perforated with nineteen (19) elements that were made of aluminum rods. Two (2) rod aluminums type with nineteenth (19) elements that signify different frequencies. The gain of this antenna is 6.67 which is required preamplifier to amplify the signal of the Sun. From the results, we found that the effective temperature of the antenna is 1.3 dB and the temperature of the Sun during that observation is 1578 K. Some suggestions on improving this design are also presented.
Abstract: The Log Periodic Dipole Antenna (LPDA) performance of solar burst monitoring in the range of (45 -870) MHz is presented. This project is under the International Space Weather Initiative (ISWI) program in order to observe the solar activities within 12 hours per day. At the first stage, we make an effort by constructing LPDA that suitable with the c...
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Peculiarities of Magnetocaloric Effect in Manganites Connected with Magnetic Heterogeneous State
L. I. Koroleva,
A. S. Morozov
Issue:
Volume 2, Issue 2, March 2013
Pages:
61-67
Abstract: Magnetocaloric effect (MCE) or T-effect was studied in La1-xSrxMnO3, Sm0.55Sr0.45MnO3 and PrBaMn2O6 manganites. It has been found that the maximum value of MCE, measured by direct method, is far less than obtainable by computation from the change of the magnetic entropy in Curie temperature TC. This phenomenon is explained by presence in them of the magnetic two-phase ferromagnetic (F) – antiferromagnetic (AF) state. So in La1-xSrxMnO3 the negative contribution from AF portion of sample lowers MCE and displacesmaximum on T(T)-curve to the higher temperature than TC on 20-40 K. Maximum on T(T) curve of Sm0.55Sr0.45MnO3 is disposed near TC=134 K in the cooling in the air single-crystal and ceramic samples. The cooling inoxygen of single-crystal,restored the Mn-O-Mn broken connections, increases the volume of clusters with CE-type of AF order, results to that maximum on T(T) curve is disposed at Neel temperature TN of this phase (243 K). Magnetic field, applied to sample during T-measurement, transforms AF clusters into F state and theboth types of clusters decompose at TN. The PrBaMn2O6 manganite has two phase transactions: paramagnetic–F at TC=295 K and F–AF at TN=231 K. Phase with spontaneous magnetization obtains the understated magnetic moment. Curve T(T) has the wide maximum near TC and the sharp minimum near TN with the small T-values in both extremes: 0,13 K and - 0,2 K respectively. This is connected with presence of AF interactions in F phase and F interactions in AF phase.
Abstract: Magnetocaloric effect (MCE) or T-effect was studied in La1-xSrxMnO3, Sm0.55Sr0.45MnO3 and PrBaMn2O6 manganites. It has been found that the maximum value of MCE, measured by direct method, is far less than obtainable by computation from the change of the magnetic entropy in Curie temperature TC. This phenomenon is explained by presence in them of t...
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Formation of Relativistic Non-Viscous Fluid in Central Collisions of Protons with an Energy of 0.8 Tev with Photoemulsion Nuclei
U. U. Abdurakhmanov,
V. V. Lugovoi
Issue:
Volume 2, Issue 2, March 2013
Pages:
68-70
Abstract: By the methods of mathematical statistics we test a qualitative prediction of the old theory of relativistic hy-drodynamics non-viscous liquid which can be used as a part of the process of hadronization within the modern hydrody-namical approach for the description of the quark-gluon plasma. Experimental data on the interaction of protons with the energies of 0.8 TeV with emulsion nuclei are used. Results do not contradict the formation of relativistic ideal non-viscous liquid in rare central collisions.
Abstract: By the methods of mathematical statistics we test a qualitative prediction of the old theory of relativistic hy-drodynamics non-viscous liquid which can be used as a part of the process of hadronization within the modern hydrody-namical approach for the description of the quark-gluon plasma. Experimental data on the interaction of protons with the ...
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A Study of Droplet Evaporation
Koffi Sagna,
Amah D’Almeida
Issue:
Volume 2, Issue 2, March 2013
Pages:
71-76
Abstract: We investigate the problem of the vaporization of a liquid droplet in a hotter environment of the same fluid. The Navier-Stokes equations are solved for a physical model which assumes spherical symmetry and laminar conditions in the quasi steady case. The study is mainly characterized by the fact that the equation of conservation of momentum is effectively taken into account and the velocity of the drop is not always uniform. Recession laws which are different from the classical d^2 law can be derived from the zeroth order approximation solution. Additional assumptions on the thermodynamical properties of the gas phase in subcritical conditions restore the classical law and permit the determination of an analytic expression for the vaporization ratio K. The analysis of the evolution of the temperature, the density and the velocity in the droplet and in the gaseous phase reveals the existence of shock waves which develop from the center of the droplet towards its boundary and an unbalanced energetic layer attached to the interface when the velocity is not uniform in the drop.
Abstract: We investigate the problem of the vaporization of a liquid droplet in a hotter environment of the same fluid. The Navier-Stokes equations are solved for a physical model which assumes spherical symmetry and laminar conditions in the quasi steady case. The study is mainly characterized by the fact that the equation of conservation of momentum is eff...
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Investigation of Structural, Electronic and Optical Properties of KCdF3
M. Nurullah Secuk,
Emel Kilit Dogan,
urat Aycibin,
Bahattin Erdinc,
Harun Akkus
Issue:
Volume 2, Issue 2, March 2013
Pages:
77-80
Abstract: The structural, electronic and optical properties of KCdF3 are investigated using the density functional theory (DFT) within the generalized gradient approximation (GGA). The calculated lattice parameters have been compared to experimental results and demonstrated to be in good agreement with them. The calculated electronic band structure of cubic KCdF3 shows that crystal has a indirect forbidden band gap with value of 2.95 eV from the high symmetry point R to gamma point in the first Brillouin Zone (BZ). The optical spectra are investigated under the scissor approximation in the photon energy range, up to 30 eV. The dielectric function and some optical constants such as energy loss functions, reflectivity, extinction, and absorption coefficients, effective number of valance electrons and refractive index are calculated.
Abstract: The structural, electronic and optical properties of KCdF3 are investigated using the density functional theory (DFT) within the generalized gradient approximation (GGA). The calculated lattice parameters have been compared to experimental results and demonstrated to be in good agreement with them. The calculated electronic band structure of cubic ...
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Point groups in solid state physics I: Point group Oh
Ayse Delibas,
Vildan Aykan,
Deniz Turkkan,
Harun Akkus
Issue:
Volume 2, Issue 2, March 2013
Pages:
81-87
Abstract: he definitions of all symmetry operations, their permutation counterparts and matrix representations, the multiplication table, all classes, abelian subgroups, and some other subgroups of point group Oh are clearly obtained. For every symmetry operation (or element) of Oh, appropriate figures are pictured for the sake of clarity.
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Ab Initio Calculations for Properties of Laves Phase V2m (M = Zr, Hf, Ta) Compounds
T. Chihi,
M. Fatmi,
B. Ghebouli
Issue:
Volume 2, Issue 2, March 2013
Pages:
88-92
Abstract: A first-principles plane-wave pseudopotentials method based on the density functional theory (DFT), is used to investigate the structural, mechanic and electronic of Laves phase V2M (M = Zr, Hf, Ta) compounds. It is found that V2Hf is mechanically unstable because this compound do not satisfy the conditionC_11-C_12> 0 below 6.27 GPa, it becomes stable beyond this pressure, the bulk modulus B revealing the largest B values for V2Ta compound which are the stable ground state phases according to the total energies. Also there is a strong interaction between V and V, the interaction between M (M = Zr, Hf, Ta) and V is more strong and between M and M is the strongest.
Abstract: A first-principles plane-wave pseudopotentials method based on the density functional theory (DFT), is used to investigate the structural, mechanic and electronic of Laves phase V2M (M = Zr, Hf, Ta) compounds. It is found that V2Hf is mechanically unstable because this compound do not satisfy the conditionC_11-C_12> 0 below 6.27 GPa, it becomes sta...
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On the Bond between the Chemical Reaction Rate and the Velocity of the System under Study
Issue:
Volume 2, Issue 2, March 2013
Pages:
93-97
Abstract: On the basis of special relativity and irreversible thermodynamics it is shown how the chemical reaction rates vary under relativistic conditions. It is shown as well that the absolute temperature T will vary according to X.Ott under these conditions. It can be represented as the trace of the tensor of rank 2.
