October 2013
Factors influencing the performance and efficiency of solar water pumping systems: A review
The world is having an energy crisis and currently there is a strong drive towards renewable energy. A renewable energy option is solar energy, where by means of photovoltaic (PV) modules electrical energy can be produced. A residential as well as industrial application for these PV modules is solar water pumping systems. Disadvantages of solar water pumping systems are low performance and low energy efficiency. This...
October 2013
A supplement to the Michelson-Morley experiment
Based on the great Michelson-Morley experiment and predecessors’ analyses, this famous experiment was reviewed under the principle that velocity of light is independent of the motion of the light source emitting or reflecting it, mainly on time difference or optical path difference (OPD). We will discover in this work that predecessors’ analysis on the famous experiment may be improper, and that there is no...
October 2013
Solution and dynamics of a fourth rational difference equation
In this paper, we get the form of the solutions of the following nonlinear recursive sequences of order four where the initial conditionsare arbitrary real numbers. Also, we study some qualitative behaviors of the solutions as periodicity character of the solutions of these different equations and we obtain the equlibrium points of considered difference equations in order to investigate the local...
October 2013
Vibration reduction and stability study of a dynamical system under multi-excitation forces via active absorber
An active vibration absorber for suppressing the vibration of the nonlinear system when subjected to external and parametric excitations forces will be studied. The aim of this paper is to study the effect of the nonlinear controller on the vibrating system. The approximate solutions up to the second order are derived using the method of multiple scale perturbation technique near the primary, principal parametric...
October 2013
Thermo-electrical characterization of Lead-Cadmium (Pb-Cd) alloys
Thermal conductivities of solid phases for pure Lead (Pb) and Pb-x wt.% Cadmium (Cd) (x = 3.3, 5, 12, 17.4, 50, 95, 99.75) binary alloys were measured with a radial heat flow apparatus. The variations of electrical conductivity (σ) on temperature and composition for the Pb-Cd alloys were measured with DC four-point probe technique. It has been observed that the electrical conductivity of Cd-based Pb-Cd alloys...
October 2013
Electrical, structural and thermal properties of graphite/silicone blends
We report the results of electrical, structural and thermal investigations on graphite/Silicone blends (G/Silicone), obtained by dispersion of graphite powder in an insulating matrix of rubber silicone. The X-ray diffraction analysis showed crystalline structure for our all studied (G/Silicone) blends. Conductivity measurements were reported in the temperature range of 298 to 423 K. The blends showed percolation...
October 2013
Seismic refraction and resistivity imaging for assessment of groundwater seepage under a Dam site, Southwest of Saudi Arabia
Seismic refraction and resistivity imaging methods were used to investigate a Dam site in Southwest Saudi Arabia to delineate the source and pathway of groundwater seepage in the site. The selected methods have the possibility to give an image of the subsurface and map lateral and vertical variations in the subsurface geology of the site. For this purpose, 48-channels seismograph with geophone spacing of 5 m,...
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