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Your search keyword '"Sabbagh, H. A."' showing total 42 results
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42 results on '"Sabbagh, H. A."'

9. STRUCTURE CHARACTERIZATION OF CALCIUM DEFICIENT ELEMENT-SUBSTITUTED HYDROXYAPATITE WITH CONSTANT DOPANT RATIO OF DIFFERENT ELEMENTS.

Author

Al-Sabbagh, H., Salih, W. K., Thajeel, K. M., and Goloshchapov, D. L.

Subjects
*HYDROXYAPATITE, *RAMAN spectroscopy, *CALCIUM, *RAMAN scattering, *ATOMIC radius
Abstract

The element-substituted calcium Deficient hydroxyapatite samples were synthesized using liquid-phase precipitation method. Different element ions (Mg+2, Zn+2, and Cu+2) were added at constant ratio (5% wt.). The phase composition of the element-substituted calcium hydroxyapatite samples was investigated by using X-ray diffraction. A comparison with known characteristics of the synthetic ion-substituted forms of hydroxyapatite was conducted. It was determined, that the investigated materials are single-phase solid solutions of the element-substituted hydroxyapatite. By the methods of IR spectroscopy and Raman scattering (RS) it was discovered the dependence of incorporation of the carbonate anion that occupies a positions of phosphorus-oxygen groups in the hydroxyapatite structure as a result of embedding element ions (Zn+2, Cu+2, Mg+2) in the crystal lattice. Besides, It was determined, that the ratio of the intensities for the C03 group mode to the P04 groups mode depended on the nature of the element atom, which replace the calcium in the lattice of HAP, and reduced by substituting the calcium atoms by the atoms of Zn, Cu, and Mg from 0.15 to 0.06. Modeling of the vibration modes of Raman spectroscopy showed that incorporation of carbon atoms to the hydroxyapatite structure correlate with the Zn, Cu and Mg atomic radius, charge, and activity. [ABSTRACT FROM AUTHOR]

Published
2020
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10. Eddy-current probe impedance due to a volumetric flaw.

Author

Bowler, J. R., Jenkins, S. A., Sabbagh, L. D., and Sabbagh, H. A.

Subjects
EDDY currents (Electric), ELECTRONIC probes
Abstract

Presents a study that described theoretical predictions of eddy-current probe responses for surface cracks with finite opening. Flaw excitation; Integral formulation; Description of unperturbed field.

Published
1991
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19. Experimental studies of the non-adiabatic escape problem

Author

Arrayas, M., Khovanov, I. A., Luchinsky, D. G., Mannella, R., McClintock, Peter V. E., Greenall, M., Sabbagh, H., Arrayas, M., Khovanov, I. A., Luchinsky, D. G., Mannella, R., McClintock, Peter V. E., Greenall, M., and Sabbagh, H.

Abstract

Noise-induced transitions between coexisting stable states of a periodically driven nonlinear oscillator have been investigated by means of analog experiments and numerical simulations in the nonadiabatic limit for a wide range of oscillator parameters. It is shown that, for over-damped motion, the field-induced corrections to the activation energy can be described quantitatively in terms of the logarithmic susceptibility (LS) and that the measured frequency dispersion of the corresponding corrections for a weakly damped nonlinear oscillator is in qualitative agreement with the theoretical prediction. Resonantly directed diffusion is observed in numerical simulations of a weakly damped oscillator. The possibility of extending the LS approach to encompass escape from the basin of attraction of a quasi-attractor is discussed.

Published
2000

20. Thermal noise in spin-phonon systems.

Author

Sabbagh, H. A

Subjects
Physics, General
Abstract

Spin-phonon systems thermal noise, based on combined lattice and spin lattice Hamiltonian densities, applied to acoustic noise field measurements

Published
1969

21. Thermal noise in spin-phonon systems

Author

Sabbagh, H. A

Subjects
Physics, Solid-State
Abstract

Canonical field equations for determining thermal noise in spin-phonon systems

Published
1968

22. Notes on the spin-Hamiltonian

Author

Sabbagh, H. A

Subjects
Physics, Solid-State
Abstract

Paramagnetic ion interaction with its crystal lattice in applied dc magnetic field, described by function of total spin resulting from unpaired electrons within ion

Published
1966

24. Efficient Solution of Electromagnetic Scattering Problems Using Spatial Decomposition Algorithms.

Author

Knopp, J. S., Sabbagh, H. A., Aldrin, J. C., Murphy, R. K., Sabbagh, E. H., Hoffmann, J., and Steffes, G. J.

Subjects
*INTEGRAL equations, *ELECTROMAGNETISM, *SCATTERING (Physics), *DECOMPOSITION method, *ALGORITHMS, *FINITE element method
Abstract

This paper introduces spatial decomposition algorithms to the volume integral method, which will enable the integral equation method to efficiently solve electromagnetic scattering problems where the scatterer extends across several layers or multiple scatterers exist in multiple layers. Model comparisons with the finite element methods are used validate the approach. Studies of typical aging aircraft eddy current inspection problems are conducted using the new formulation. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2006
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25. Numerical and Experimental Study of Eddy Current Crack Detection around Fasteners in Multi-Layer Structures.

Author

Knopp, J. S., Aldrin, J. C., KO, R. T., and Sabbagh, H.

Subjects
EDDY currents (Electric), HOLES, NONDESTRUCTIVE testing, AIRFRAMES, ELECTRONIC probes, TESTING
Abstract

Previous work on the detection of cracks around fastener holes in multi-layer structures using eddy current NDE has met with some success; however, challenges remain in detecting smaller corner cracks while minimizing false call rates. To address this issue, a 3D model was developed for this problem and successfully validated with experimental data. Using this model, a series of numerical studies were performed to identify potential features for defect classification. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2004
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35. Experimental studies of the non-adiabatic escape problem

Author

Arrayas, M., Khovanov, I. A., Luchinsky, D. G., Mannella, R., McClintock, P. V. E., Greenall, M., Sabbagh, H., Arrayas, M., Khovanov, I. A., Luchinsky, D. G., Mannella, R., McClintock, P. V. E., Greenall, M., and Sabbagh, H.

Abstract

Noise-induced transitions between coexisting stable states of a periodically driven nonlinear oscillator have been investigated by means of analog experiments and numerical simulations in the nonadiabatic limit for a wide range of oscillator parameters. It is shown that, for over-damped motion, the field-induced corrections to the activation energy can be described quantitatively in terms of the logarithmic susceptibility (LS) and that the measured frequency dispersion of the corresponding corrections for a weakly damped nonlinear oscillator is in qualitative agreement with the theoretical prediction. Resonantly directed diffusion is observed in numerical simulations of a weakly damped oscillator. The possibility of extending the LS approach to encompass escape from the basin of attraction of a quasi-attractor is discussed.

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