Alsaedi M.A.,University of Misan
Journal of Vibroengineering | Year: 2014
The partial discharge (PD) phenomenon is very harmful for electrical appliances and its early detection could be a cost effective approach for the industry. Although many techniques are used for PD detection yet no technique has presented widely acceptable solution. Still the subject needs parallel study of the detection techniques. In this experimental, multimode fiber (MMF) was placed in oil tank. The PD induced acoustic emission (AE) inside the insulation oil. PD signal has been captured by using step-index multimode of fiber optic sensor (FOS). The results shows FOS has good sensitivity in the range of applied high voltage 10 kV. © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING.
Al-Lami A.K.A.,University of Misan
Journal of Polymer Research | Year: 2015
Two new series of supramolecular liquid crystalline block copolymers have been synthesized. The first, is based on a backbone that contains carboxylic acid groups. The second is a side chain block copolymer exhibiting hydrogen bonding between the carboxylic acid and the pyridine moiety of a simple low molar mass molecule. These copolymers contain two different flexible spacer lengths, the first fixed at two methylene groups, while the other spacer varies from two to seven groups. The phase behavior and transitional properties of these series have been analyzed by optical polarized microscopy and differential scanning calorimetry, while the structures and properties of the prepared compounds were determined by spectroscopic techniques, elemental analysis, thermogravimetric analysis, and powdered X-ray diffraction. © 2014, Springer Science+Business Media Dordrecht.
Al-Zahy Y.M.A.,University of Misan
Optical Engineering | Year: 2014
An analytical solution of the generalized nonlinear Schrodinger equation which is implemented with fiber laser applications has been presented. The solution based on the exp-function method which is depending on time, space and small perturbations has been found. This solution was used to test the behavior and study the propagation characteristics of laser pulses and compared with some of the researches in the same field and the nonlinear effects as gain dispersion, second anomalous group velocity dispersion, self phase modulation, and frequency are investigated. The net results are that the parabolic pulse growth after z = 4 m, and generate a periodic pulse train, the power of pulse is increased with increasing the length of fiber laser with reduce its width, the nonlinear effects have a small role on the pulse power, but they effect on the modulation stability of the laser and lead to generate sideband, the behavior of the pulse converted to chaotic when increasing the frequency. © 2014 Society of Photo-Optical Instrumentation Engineers (SPIE).
Al-Zahy Y.M.A.,University of Misan
Optical Engineering | Year: 2015
We investigate the generation of a chirped pulse in a single-mode, ring-cavity, erbium-doped fiber laser employing carbon nanotubes (CNTs) as a saturable absorber (SA). The pulse propagation is simulated using analytical methods to understand and quantify the role of multiple SA properties, particularly in the propagation dynamics of the laser pulse. The soliton solution is obtained on the basis of nonlinear effects, such as gain dispersion, second anomalous group-velocity dispersion, self-phase modulation, and two-photon absorption for a generalized nonlinear Schrodinger equation. The influences of the SA parameter in the range from 0.1 to 0.4 on the chirp, power, and width of the soliton are calculated. A stable, passively mode-locked fiber laser using CNTs as an SA is modeled. In addition, the power, width, chirp, and phase of the soliton pulses can be tuned by choosing suitable SA parameters. © The Authors.
Al-Lami A.K.,University of Misan
Polycyclic Aromatic Compounds | Year: 2015
Two new series of hydrogen bonding liquid crystal dimers were prepared and their self-assemble behavior and structure–property relationships were studied through intermolecular hydrogen bond formation. The first series of symmetric liquid crystal dimers have two terminal alkoxy chains and the second have four terminal alkoxy chains. Their structures were elucidated using spectroscopic techniques, elemental analysis, and powdered X-ray diffraction. The mesophases and their corresponding transition temperatures were identified by differential scanning calorimetric measurements and polarized optical microscope. 2015 Copyright © Taylor & Francis Group, LLC