Advances in Physics Theories and Applications
http://www.iiste.org/Journals/index.php/APTA
en-USadmin@iiste.org (Alexander Decker)admin@iiste.org (John Nagoo)Wed, 31 Jan 2018 10:06:39 +0000OJS 2.3.7.0http://blogs.law.harvard.edu/tech/rss60Journal coverpage
http://www.iiste.org/Journals/index.php/APTA/article/view/40556
Journal coverpageJournal Editorhttp://www.iiste.org/Journals/index.php/APTA/article/view/40556Effects of Number of Wells and Cavity Length in Limitation the Optimum Symmetric Multiple Quantum Well Laser
http://www.iiste.org/Journals/index.php/APTA/article/view/40557
<p>In this research several main parameters/factors that effect on each of structures of semi-conductor lasers have been investigated. This investigation depends mainly on two procedures: first one is classification for these parameters including each of threshold current density, injecting threshold carrier density, absolute threshold current density and their relations with each of number of wells and cavity length, and the second is simulation process for the previous parameters with variable values of number of wells and cavity length. Non ideal contribution to the total output current like Auger recombination, Interface recombination and Leakage recombination have also been estimated through the simulation process. In other words, this research is devoted to specify the optimum performance of multi-quantum well structure of semi-conductor laser.The calculations were performed for a representative separate confinement multiple quantum well laser structure in GaAs/AlGaAs system of: 7.5nm as a quantum well size, 250 nm as a thickness of the waveguide region and 8nm as a barrier size.</p>Maysam T. Al-Obaidihttp://www.iiste.org/Journals/index.php/APTA/article/view/40557Double Diffusive Convection and Internal Heat Generation with Soret and Dufour Effects over an Accelerating Surface with Variable Viscosity and Permeability
http://www.iiste.org/Journals/index.php/APTA/article/view/40558
<p class="TTPAbstract">The study deals with the coupled highly non-linear partial differential equations for the effects of internal heat generation (IHG), combined effects of Soret and Dufour with variable fluid properties like variable porosity, permeability and viscosity on thermal and diffusion mixed (free and forced) convection flow fluid through porous media over moving surface. The numerical computation has been carried out for other additional terms like internal heat generation (IHG), viscous dissipation and ohmic effect. We have drawn the numerical results and presented graphically for the flow characteristics like velocity, temperature and concentration for the effect of IHG, Soret and Dufour effects on mixed (free and forced) convective flow with variable fluid properties for various non-dimensional parameters namely prandtl number, Eckert number, porous parameter, viscosity parameter, Soret number and Dufour number of the problem using the shooting technique. In the absence of the additional terms and for constant viscosity our computational results are compared with the earlier works and found to be good agreement.</p> <p class="TTPSectionHeading">Keywords:Double diffusive, internal heat generation (IHG), Soret and Dufour effects, variable permeability, accelerating surface.</p>M. Girinath Reddy, Dinesh P. Ahttp://www.iiste.org/Journals/index.php/APTA/article/view/405583D Magneto Hydrodynamic Slip Flow of Al50Cu50-Water and Cu-Water Nanofluids over a Variable Thickness Stretched Surface
http://www.iiste.org/Journals/index.php/APTA/article/view/40559
<p class="TTPAbstract">The current paper covers the examination of 3D magneto hydrodynamic nanofluid motion past a slendering (variable thickness) stretching surface under the influence of MHD, Soret and Dufour effects, thermophoresis, Brownian motion and slip impact. For this study, we considered the Cu-water and Al<sub>50</sub>Cu<sub>50</sub>-water nanofluids past a non-uniform thickness stretching surface. With the help of similarity transformations, we transformed the derived governed equations as ordinary differential equations. The mathematical outcomes determined by employing Runge-Kutta and Newton’s methods. We reveal and interpretation the graphs for different parameters like magnetic number, volumetric fraction, Soret number, Dufour number, Brownian motion, thermophoresis parameter, stretching parameter, slip parameters h<sub>1 </sub>and h<sub>2</sub>. We discussed the skin friction coefficient, reduced Nusselt and reduced Sherwood numbers for the influence of the pertinent parameters with the assistance of tables separately for two nanofluids (Cu-water and Al<sub>50</sub>Cu<sub>50</sub>-water nanofluids). Results are validated by comparing with the published results and found a favorable agreement.</p> <p class="TTPSectionHeading">Keywords: Slip flow, Slendering sheet, Cross diffusion, MHD.</p>M. Bharath Kumar, B. Shanmukhahttp://www.iiste.org/Journals/index.php/APTA/article/view/40559An Experimental Method to Study the Structural Differences of Surface Barrier Detectors by Studying the Energy Distribution of Noise
http://www.iiste.org/Journals/index.php/APTA/article/view/40560
<p>In this paper, we studied two surface barrier detectors, which are different in polarity and contacts. Where in the first detector, the negative pole is made of gold and the positive one is made of aluminum. While in the second detector, the situation is reversed. This study showed that the design of the first detector is better than the second one because it emitted less noise. This is because ionization potential of gold is smaller than that of aluminum.<strong></strong></p> <p><strong>Keywords</strong>: surface barrier detectors, distribution of noise.</p>Mai Razzok, Abdullah Rastanawihttp://www.iiste.org/Journals/index.php/APTA/article/view/40560Quantum Nature of Light in Displaced Squeezed Chaotic State
http://www.iiste.org/Journals/index.php/APTA/article/view/40561
<p>In this work the squeezing and statistical properties for single-mode displaced squeezed chaotic state is analyzed with the help of the density operator for a single-mode light. It is found that the effect of the thermal light is to reduce the quadrature squeezing but increases the mean photon number. According to the generated results of analyzing the quadrature squeezing, the system has 98.17% of squeezing (in squeezed state) in which the system initial to be in vacuum state (no photon at all) and occurs at the squeeze parameter ( ). In addition, the squeeze parameter enhances both the quadrature squeezing and the mean photon number.</p> <p><strong>Keywords: </strong>Squeezing, Single-mode light, Thermal light, Photon Statistics</p>Sitotaw Eshetehttp://www.iiste.org/Journals/index.php/APTA/article/view/40561