Open Access Original Research Article

Analytical Investigation of Electrons Capture Time Effect on the Threshold Current Density Reduction in QD Spin-Lasers

S. N. Hosseinimotlagh, H. Ghavidelfard, A. Shakeri

Physical Science International Journal, Page 1050-1064
DOI: 10.9734/PSIJ/2014/9676

In this paper, we solve numerically the rate equations governing the  semiconductor spin with un-polarized and polarized laser field based on quantum dot active region in which Schottky tunnel barrier treats as the spin injector. We demonstrate simultaneously the effects of electron capture time, and injected current polarization on threshold current density reduction and normalized spin-filtering interval. The threshold current density reduction and normalized spin-filtering interval increases simultaneously with electrons capture time reduction and increase of injected current polarization. The maximum obtained threshold current density reduction and normalized spin-filtering interval values are0.353 and 0.90, respectively. We also calculate the spin-up optical gain and obtain the conditions for achieving optimum optical gain. The maximum obtained spin-up optical gain value is 17.70.

 

Open Access Original Research Article

D-optimal Exact Design: Weighted Variance Approach and a Continuous Search Technique

Otaru O. Paul, Enegesele Dennis

Physical Science International Journal, Page 1065-1072
DOI: 10.9734/PSIJ/2014/9141

In design of experiment, researchers have formulated various methods for obtaining D-optimal design. The aim of this study therefore is to obtain an N-point exact D-optimal design for a feasibleregion defined on a polynomial model. The weighted variance approach and a continuous search technique were used to obtain a D-optimum measure. The illustrative example buttresses the effectiveness of the method. The minimum variance was obtained in the first iteration and needs no further improvement.

 

Open Access Original Research Article

The Magnetized Plasma Effect on Cathode Fall Thickness for Helium Gas Discharge

Ahmed Rida Galaly

Physical Science International Journal, Page 1088-1099
DOI: 10.9734/PSIJ/2014/9605

Our previous study showed that the thickness of the cathode fall region in magnetized DC argon plasma was about 3.3mm has been investigated using two different methods, namely: the axial potential distribution and the current density distribution along the glow discharge regions. The present study demonstrates the same measurements but carried out for Helium gas discharge at the edge and center of the cathode surface for the same characteristic of the DC (cold cathode) magnetron sputtering unit. The Ia–Va characteristic curves of the glow discharge and the axial potential distribution and the current density distribution have been investigated. Under the influence of magnetic field, the thickness of the cathode fall region for he discharge is about 2.5mm for the two methods in pressure (P) range of 1-4mbar. Apparently for helium gas discharge, a reduction of the cathode fall thickness (about 20%) has been found in the presence of a magnetic field at the center of the cathode and (about 37%) at the edge, furthermore stronger electric field at the edge of the cathode fall, and hence high rates of sputtering are expected.

 

Open Access Original Research Article

Preparation, Microstructural and Optical Characterization of NiO Nanoparticles

M. A. Kaid

Physical Science International Journal, Page 1100-1109
DOI: 10.9734/PSIJ/2014/11068

A fine NiO powders were prepared by a homogeneous precipitation method with an aqueous solution of nickel nitrate hexahydrate and citric acid. The microstructure, surface morphology of NiO were characterized by thermo gravimetric (TGA) analysis and differential scanning calorimeter (DSC), X-ray diffraction (XRD), scanning electron microscope (SEM) , infrared (IR) spectroscopy. The experiment results show that the NiO nanoparticles are cubic structure with spherical shape and well dispersed, the particle size distribution ranging from 7 to 28nm with the average particle size is about 15.5nm. The infrared absorption band of NiO nanoparticles shows blue shifts compared with that of bulk NiO. The optical band gap energy value 3.81eV has been determined from absorbance spectra in strong absorption region.

 

Open Access Original Research Article

Multidimensional Treatment of the Expanding Universe

I. A. Urusovskii

Physical Science International Journal, Page 1110-1144
DOI: 10.9734/PSIJ/2014/10270

The simplest six-dimensional treatment of the expanding Universe in the form a three-dimensional sphere appeared as a result of the intersection of three simplest geometrical objects of finite sizes in the six-dimensional Euclidean space – of three uniformly expanding five-dimensional spheres – with account of an increase of speed of light in cosmic time (a measure of expansion of five-dimensional spheres) is given. Its effect on redshift for distant sources and theoretical redshift dependencies compared with observed data are demonstrated. A scenario in which the speed of elementary particles, including photons, in the six-dimensional space is constant in cosmic time is considered. This scenario corresponds to the energy conservation condition in that space. Some difficulties of standard cosmology are discussed on the base of six-dimensional cosmology. Recurrent formulas generalized the theory on the case when three original perturbations in the form of (n-1) - dimensional spheres expand in -dimensional space.

Open Access Original Research Article

Computational Solution to Quantum Foundational Problems

Arkady Bolotin

Physical Science International Journal, Page 1145-1157
DOI: 10.9734/PSIJ/2014/11144

This paper argues that the requirement of applicableness of quantum linearity to any physical level from molecules and atoms to the level of macroscopic extensional world, which leads to a main foundational problem in quantum theory referred to as the “measurement problem”, actually has a computational character: It implies that there is a generic algorithm, which guarantees exact solutions to the Schr¨odinger equation for every physical system in a reasonable amount of time regardless of how many constituent microscopic particles it comprises. From the point of view of computational complexity theory, this requirement is equivalent to the assumption that the computational complexity classes P and NP are equal, which is widely believed to be very unlikely. As demonstrated in the paper, accepting the different computational assumption called the Exponential Time Hypothesis (that involves P≠NP) would justify the separation between a microscopic quantum system and a macroscopic apparatus (usually called the Heisenberg cut) since this hypothesis, if true, would imply that deterministic quantum and classical descriptions are impossible to overlap in order to obtain a rigorous derivation of complete properties of macroscopic objects from their microstates.

Open Access Original Research Article

Electro-gravitational Technology via Chronon Field

Eytan H. Suchard

Physical Science International Journal, Page 1158-1190
DOI: 10.9734/PSIJ/2014/11129

Aim: To develop a model of matter that will account for electro-gravity.

Matter is characterized by force fields and in non-inertial and non-geodesic motion as a result of interactions. The measurement of how non geodesic a test particle is can be done by non-geodesic acceleration which in 4 dimensional space-time is perpendicular to the 4-velocity. In order to give a new meaning to matter by using such acceleration there is a need to reach a formalism free of specific trajectories, namely by a scalar curvature field. This can be done by an introduction of a new meaning of time that can't be realized as a coordinate. From every event, we define the limit of the maximal possible measurable proper time back to the "big bang" singularity or manifold of events from which we can say cosmic expansion had began. Yet such time is not a physical observable in the sense that it can't be locally calculated and it may exist as a limit only. The gradient of such time, however, is local and thus "physical". If more than one curve measuring such time cross the same event then the gradient which is a vector field can't be parallel to all such intersecting trajectories. That implies that the gradient as a vector field will not be parallel to itself or in other words, will manifest a curvature field. This idea leads to a new formalism of matter that replaces the conventional stress-energy-momentum-tensor. The formalism will be mainly developed for classical but also for quantum physics and will result in a theory of electro-gravity.

 

Open Access Original Research Article

Urban Sprawl Analysis and Transportation Using Cellular Automata and Markov Chain

J. O. Olusina, E. O. Abiodun, J. I. Oseke

Physical Science International Journal, Page 1191-1210
DOI: 10.9734/PSIJ/2014/9211

The uncontrolled urban spread (urban sprawl) has both positive and negative implications. The adverse effects are more pronounced than its gains. Among others adverse effects is infrastructure provision (such as roads, etc.) which usually becomes a problem. This work examines the effects of urban sprawl in three (3) Local Government Areas (LGAs) of Lagos State so as to determine changes that have taken place between 1984 and 2006. Land Consumption Rate and Land Absorption Coefficient were introduced to aid in the quantitative assessment of the change, urban sprawl models were developed and the spread of urban sprawl in the next 14 years (2006 to 2020) were projected.

Lands at Imageries of three epochs (1984, 2000 and 2006) were processed, classified and analysed. CA-Markov modelling was carried out to predict for 2020. From the research, it was discovered that the Built-up Areas will increase from 8.76% to 17.60% of the Land use/land cover i.e. continuous urban sprawl in future. Finally, the adverse effects of urban sprawl on transportation in this area have resulted in high congestion cost and high level of air pollution just to mention but a few. The sprawl pattern has opened up the rural areas (such as Oniru, Ajah, Eti-Osa) and till today the sprawl is still unabated.

 

Open Access Original Research Article

A Review of the Construction of Particular Measures

Yao Elikem Ayekple, William Obeng-Denteh, Joshua Amevialor

Physical Science International Journal, Page 1211-1217
DOI: 10.9734/PSIJ/2014/10668

The first measure one usually comes into contact with in undergraduate mathematical studies is the Lebesgue measure and seeing how it is applied to the Lebesgue integral to extend considerably the Riemann integral, it doesn’t take very much else to arouse one’s interest in the study of measures and their construction with the hope/intent of eliciting their usefulness and how they are applied to other areas of mathematics. The Carath´eodory extension theorem and the Carath´eodory-Hahn theorem which are invoked subsequently in the construction of some measures are stated without proof. A large class of measures exist and this paper illustrates the construction of some of these measures including the Radon measure, the Hausdorff measure, the Lebesgue-Stieltjes measure, the Lebesgue measure in Rn and Product measures. The material presented is standard but it provides a summary of some key points on measure theory which might prove to be useful for the undergraduate.

Open Access Review Article

Non-destructive Microcracks Detection Techniques in Silicon Solar Cell

Mohd Israil, Abdul Ghani Yousseph Kerm

Physical Science International Journal, Page 1073-1087
DOI: 10.9734/PSIJ/2014/8754

A very high demand and limited stock of fossil fuels, renewable energy in very particular solar energy is the mainly focused area for research these days. This review paper presents the nondestructive optical testing techniques for the solar cells. The impacts of microcracks in solar cells as well as photovoltaic modules have been studied in this paper. Laser beam induced current, electron beam induced current, electroluminescence and photoluminescence are mainly discussed techniques in this paper. All the aforementioned methods will be reviewed, highlighting some of their salient characteristics including merits and demerits. For completion and thoroughness, some image processing techniques for the shape and size detection of micro-cracks will also be discussed.