May 2009
The dynamical effect of stark-shifts produced from a four-level atomic system
We consider a two-mode quantized field described in a coherent state interacting with a four-level atom. An effective Hamiltonian is obtained by adiabatically eliminating the intermediate two levels in a cascade process. The influence of the Stark shifts on the atomic inversion is examined, as well as on the second order auto-correlation function and on the cross-correlation between the field modes. The results of the...
May 2009
On Mannheim partner curves in E3
The aim of this paper is to study the Mannheim partner curves in Euclidean space E3. We obtain the relationships between the curvatures and the torsions of the Mannheim partner curves with respect to each other. Key words: Mannheim partner curves, curvature, torsion.
May 2009
Blind signal separation using an adaptive weibull distribution
We propose an independent component analysis (ICA) algorithm which can separate mixtures of sub- and super- Gaussian source signals with self-adaptive nonlinearities. The ICA algorithem in the framework of natural Riemannian gradient is derived using the parameterized Weibull density model. The nonlinear function in ICA algorithem is self-adaptive and is controlled by the shape parameter of Weibull density model....
May 2009
The seasonal variation of ph and dissolved oxygen (dO2) concentration in Asa lake Ilorin, Nigeria
The vertical and surface water variations of pH and dissolve oxygen (DO2) concentration were studied for 12 months (March 2005 to February 2006) in Asa lake Ilorin, Nigeria. The mean surface pH values ranged between 7.30 and 8.10, with lower values (7.30 - 7.70) obtained October to December while higher values (8.0/8.10) were obtained in January to July. Vertical distribution of mean pH also ranged from 8.1 (Surface) to...
May 2009
Hydrogeophysical investigation of groundwater potential in Emu kingdom, Ndokwa land of Delta State, Nigeria
A study of 10 vertical electrical soundings from different quarters of Emu kingdom using Schlumberger array were undertaken. This is an attempt to obtain useful information on the aquifer distribution within the area and hence delineate possible site boreholes could be drilled for potable and sustainable water supply. Based on the geoelectric section which is in agreement with the driller’s log, the best...
May 2009
Transfer of natural radionuclides from soil to plants in tropical forest (Western Ghats – India)
Soil and 2 wild plant species (Evodia roxburghiana and Eleaocarpus oblangus)have been collected from the western Ghats region and analysed for 210Po and238U. The radioactivity concentrations in plants and soil reflect the impact of the existence of igneous nature of rock in the area of study. Concentration ratios (CR) of these radionuclides, between plants and underlying soil, have been studied and...
May 2009
Topography measurement of nano silicon oxide film
The Si (111) – 7 x 7 is a semimetal which its surface morphology has been normally studied with using STM (scanning tunneling microscopy) technique, whilst the other kind of silicon, such as Si(100) – 2 x 1 is not a semimetal. For letter surface structure, the AFM (atomic force microscopy) technique can be used as well. There are two main issues which are threatening the use of STM technique as a good...
May 2009
Regulation of the electric power provided by the panels of the photovoltaic systems
In this paper we analyzed in Pspice the influences of the solar radiation and the temperature on the optimal operation of the photovoltaic (PV) panels and the PV systems provided with an MPPT command (CFV) which fixes a voltage (Vopt) at output of PV panel. We have shown that the Vopt voltage depends on the seasons and function of the temperature. Between winter and summer the variation can reach 1V. This variation...
May 2009
Analytical study of electromagnetic wave scattering behaviour using Lippmann-Schwinger equation
An analytical study of electromagnetic wave scattering using Lippmann-Schwinger equation is presented in this work. Lippomann-Schwinger equation was derived first from hamiltonian that involves non-interacting and interacting terms. The solution for non-interacting and out going scattered waves was obtained using a boundary conditions specified on the green’s function which specifically handles the...
May 2009
Influence of temperature on charge transports and optical parameters for the Ge15Sb5Se80 and Ge15Sb5Te80 amorphous thin films
The thin films of chemical composition Ge15Sb5Se80 and Ge15Sb5Te80 were prepared by a thermal evaporation technique. Both the absorbance and the transmittance spectra were measured over the incident photon energy ranges 1.14 to 2.7 and 1.22 to 2.87 eV for the Ge15Sb5Se80 and Ge15Sb5Te80 films respectively. These were used for estimating the reflectance spectra in the same range of the incident photon...
May 2009
Use of finite element method as a simulation technique for bioremediation of naphthalene, anthracene and pyrene contaminated soil in a fixed bed reactor
In this work, the finite element method was applied to solve one-dimensional advective-dispersive solute transport model with linear equilibrium sorption and first-order degradation. This mathematical approach was adopted to adequately predict the effluent concentrations and breakthrough profiles of naphthalene, anthracene and pyrene. Simulation results showed that the concentrations of naphthalene, anthracene and...
May 2009
Evaluation of some physicochemical parameters of selected brands of vegetable oils sold in Ilorin metropolis
Five samples of selected brands of vegetable oils sold in Ilorin metropolis were investigated for some physicochemical parameters. Relative density, flash point, smoke point, crackle test, cold test and viscosity were determined for each sample. Also, the saponification, acids, ester and iodine values, as well as the fatty acid profile for each sample were investigated. Viscosity of the different brands of oils at...
May 2009
Foundry properties of sand cores bonded with composites of Nigerian grades 1 and 2 acacia species with bentonite clay
The permeability, green compressive and tensile strength of foundry cores bonded with composite mixtures of bentonite clay with each of grades 1 and 2 Nigerian acacia exudates were determined. Silica sand grains were used as base for the specimens which in accordance with foundry standard were cylindrically shaped for green permeability and compressive strength but shaped like figure eight for tensile strength test. A...
May 2009
Elastic-plastic transition stresses in an isotropic disc having variable thickness subjected to internal pressure
Elastic-plastic transitional stresses in an isotropic disc having variable thickness under internal pressure have been derived by using Seth’s transition theory. The effect of stresses in fully-plastic state for different values of k presented graphically and discussed. Disc made of compressible material and having variable thickness yields at some radius R1 at a higher pressure as compare to disc made of...
May 2009
Enhancing road monitoring and safety through the use of geospatial technology
The geographic information system (GIS) and the global positioning system (GPS) are the 2 geospatial technologies that are being used in monitoring of transportation generally. Transportation is a requirement for every nation regardless of its industrial capacity, political stability, population, size or technological development. Moving goods and people from one place to another is crucial to maintaining strong...
May 2009
Spermatotoxic impact of bonny light crude oil (BLCO) ingestion on adult male Swiss albino mice
Five samples of selected brands of vegetable oils sold in Ilorin metropolis were investigated for some physicochemical parameters. Relative density, flash point, smoke point, crackle test, cold test and viscosity were determined for each sample. Also, the saponification, acids, ester and iodine values, as well as the fatty acid profile for each sample were investigated. Viscosity of the different brands of oils at...
May 2009
Numerical experiment on hygro-thermal deformation of concrete with different material or structural parameters
Temperature and moisture are responsible for the deterioration processes of concrete structures, and the extensive failures in concrete elements often result from both thermal and moisture simultaneously. The influences of hygro-thermal physical parameters and structural parameters on the deformation of concrete were investigated numerically using a specially developed software, which is named Coupling...
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