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Thermodynamic Properties of Bcc Crystals Studied Based on Their High-Order Expanded Debye-Waller Factors and XAFS Application to Ferrite Iron
Dinh Quoc Vuong,
Nguyen Van Hung
Issue:
Volume 4, Issue 2, November 2016
Pages:
14-19
Received:
24 October 2016
Accepted:
4 November 2016
Published:
8 December 2016
DOI:
10.11648/j.ajea.20160402.11
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Abstract: Thermodynamic properties of bcc crystals have been studied based on the anharmonic correlated Debye model high-order expanded Debye-Waller factors and X-ray absorption fine structure (XAFS). The many-body effects are taken into account in the present one-dimensional model based on the anharmonic effective potential that includes interactions of absorber and backscatterer atoms with their first shell near neighbors, where Morse potential is assumed to describe the single-pair atomic interaction. Analytical expressions for dispersion relation, correlated Debye frequency and temperature and four first temperature-dependent XAFS cumulants of bcc crystals have been derived using the many-body perturbation approach. The obtained cumulants are applied to calculating XAFS spectra and their Fourier transform magnitude. Numerical results for Fe, a ferrite crystal, are found to be in good agreement with experiment.
Abstract: Thermodynamic properties of bcc crystals have been studied based on the anharmonic correlated Debye model high-order expanded Debye-Waller factors and X-ray absorption fine structure (XAFS). The many-body effects are taken into account in the present one-dimensional model based on the anharmonic effective potential that includes interactions of abs...
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Detection of the Magnetic Field Induced by the Wake of a Moving Submerged Body Using Simple Models
Xiangming Guo,
Dongliang Zhao,
Zhongqing Cao
Issue:
Volume 4, Issue 2, November 2016
Pages:
20-25
Received:
5 August 2016
Accepted:
1 December 2016
Published:
6 January 2017
DOI:
10.11648/j.ajea.20160402.12
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Abstract: Wakes induced by the motion of submerged bodies may extend for several kilometers and the magnetic field induced by the motion of conductive sea water in the wake of a moving body may be detected in certain condition. Numerical simulations are used to compute the characteristic of wake magnetic field and compare it with wind wave’s magnetic fields, which can be detected using the modern magnetometers. Using the spectral analysis of the samples, the results show that the spectrum has a sharp peak, which can be detected in principle depending on sensitivity of the detector, body disturbance and environmental conditions.
Abstract: Wakes induced by the motion of submerged bodies may extend for several kilometers and the magnetic field induced by the motion of conductive sea water in the wake of a moving body may be detected in certain condition. Numerical simulations are used to compute the characteristic of wake magnetic field and compare it with wind wave’s magnetic fields,...
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Design of Magnetic Metamaterial with Cells of Dual-Layer Square Spiral Resonators
Liqun Hua,
Binyang He,
Xianghong Kong,
Gaobiao Xiao
Issue:
Volume 4, Issue 2, November 2016
Pages:
26-33
Received:
14 November 2016
Accepted:
28 November 2016
Published:
6 January 2017
DOI:
10.11648/j.ajea.20160402.13
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Abstract: Artificially constructed materials, including metamaterials with negative magnetic permeability (μ) at megahertz frequencies, have been applied in various fields and the construction of new devices. Among these applications, the split-ring resonators (SRRs) and spiral resonators (SRs) are the most widely used metamaterial cells, especially in telemetry and antenna systems proposed in the past few years. In this paper, one particular cell, whose structure is square spiral wires printed on both sides of a dielectric substrate, is selected as the investigated resonator. Numerous simulations are conducted to study the properties of both magnetic resonance and effective permeability. The effect of the geometrical parameters on the resonance frequency and the impact of the number of turns of spiral resonator on the permeability are investigated. The effective permeability of the periodic SR array varies with the metal width and the gap spacing. The values of are extracted at a chosen frequency of 29.8 MHz, based on which the geometrical parameters of the SR array whose relative permeability is -1 can be determined. This kind of artificial magnetic materials are able to be used for improving the efficiency of a wireless power transfer system.
Abstract: Artificially constructed materials, including metamaterials with negative magnetic permeability (μ) at megahertz frequencies, have been applied in various fields and the construction of new devices. Among these applications, the split-ring resonators (SRRs) and spiral resonators (SRs) are the most widely used metamaterial cells, especially in telem...
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Changes in Electrical Properties Due to Gamma Irradiation of Polyvinyl Chloride (PVC)
Abdelnabi Ali Elamin,
Mohammad Hbeeb Ahmed Elkanzi,
Elfatih Ahmed Hassan,
Bashir Elhaj Ahmed,
Ali Sulaiman Mohamed Khareif
Issue:
Volume 4, Issue 2, November 2016
Pages:
34-38
Received:
24 November 2016
Accepted:
2 December 2016
Published:
12 January 2017
DOI:
10.11648/j.ajea.20160402.14
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Abstract: The electrical properties that are of major importance to the operation and lifetime of many electrical components and systems include the relative dielectric constant and relative permittivity, these properties are dependent on the chemical composition of the dielectric, they usually suffer degradation after electrical deterioration has taken place. The aim of this paper is to use the change in electrical properties with radiation dose to design polymer dosimeter. The experimental results show an improvement the relative permittivity of the medium decreased except for PE sample which increased when the total irradiation dose of gamma rays was increased whereas the relative dielectric constant increased for all PVC samples. The predominance of cross-linking results shows linear relations between relative permittivity and relative dielectric constant versus absorbed dose of gamma rays source. These relationships between these properties and dose level can be utilized as measuring tool (Dosimeter) for radiation exposure that incident on the PVC samples.
Abstract: The electrical properties that are of major importance to the operation and lifetime of many electrical components and systems include the relative dielectric constant and relative permittivity, these properties are dependent on the chemical composition of the dielectric, they usually suffer degradation after electrical deterioration has taken plac...
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Corrosion Performance of Copper - Diamond Composites in Different Aqueous Solutions
Z. Abdel Hamid,
Mona H. Gomaa,
H. B. Hassan
Issue:
Volume 4, Issue 2, November 2016
Pages:
39-49
Received:
9 December 2016
Accepted:
23 December 2016
Published:
20 January 2017
DOI:
10.11648/j.ajea.20160402.15
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Abstract: In the present work copper/diamond composites, such as (Cu-10 Vf % diamond uncoated, Cu-30 Vf % diamond uncoated, Cu-10 Vf % diamond coated NiCrB and Cu-30 Vf % coated NiCrB) as heat sink materials have been fabricated using powder metallurgy and electroless techniques. The copper powder used in this study has been fabricated using electroless technique and the diamond powder was electroless coated with NiCrB film. The copper powder have been mixed with the uncoated or coated diamond particles, milled, compacted and sintered at 900°C in a hydrogen atmosphere. The corrosion behavior of the copper composite samples has been investigated in 0.6 M NaCl, 0.1 M HCl and 0.5 M NaOH solutions using potentiodynamic polarization anodic and cathodic Tafel lines and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) linking with energy dispersive X-ray spectroscopy (EDS) has been used to investigate the surface morphology and the chemical composition of the coated layer. The results of the corrosion test illustrated that the coated and uncoated Cu/diamond composites suffer from corrosion to a different extent in various electrolytes. The lowest corrosion rate in all the studied media was recorded for Cu-10 Vf % D coated NiCrB composite compared with the massive copper or uncoated composite samples.
Abstract: In the present work copper/diamond composites, such as (Cu-10 Vf % diamond uncoated, Cu-30 Vf % diamond uncoated, Cu-10 Vf % diamond coated NiCrB and Cu-30 Vf % coated NiCrB) as heat sink materials have been fabricated using powder metallurgy and electroless techniques. The copper powder used in this study has been fabricated using electroless tech...
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