Nigerian Journal of Physics

Effects of deformation on the energies of metals

2015-05-28T15:36:15+00:00

In this work, a model for computing the correlation, binding and cohesive energy of deformed and undeformed metals was developed based on the structureless pseudopotential formalism. Based on the developed model, the correlation, binding and cohesive energy of metals were computed and studied. Also, the computed binding and cohesive energy of metals were compared with available experimental values. The results obtained showed that correlation energy increases with increase in electron density parameter, also, increase in deformation increases the correlation energy. The computed binding energy and cohesive energy of metals were in good agreement with experimental values. The results obtained further showed that deformation causes a decrease in the binding energy of metals and it does not cause a significant change in the cohesive energy of metals, although transition metals have high values of cohesive energy compared to alkaline and simple metals.

Keywords: Metals, pseudopotential model,cohesive, binding and correlation energy.

Perturbation Calculation of two-electron interaction in the ground of the Hubbard Model

2015-05-28T15:36:15+00:00

The single-band Hubbard model was studied in one dimensional lattice system which consist only of two sites. The perturbation calculation accounts for the ground state energy and its wave functions .The exact and perturbation calculation are in agreement when the value of the on-site coulomb interaction U is equal to zero.

Keywords: Hubbard model, Perturbation, electrons, and creation and annihilation operators.

Chemical Bath Deposition and characterization of CdS – PbS thin films.

2015-05-28T15:36:16+00:00

CdS–PbS thin films have been deposited on glass substrates by the chemical bath deposition technique. Cadmium sulphide thin layer was first deposited on glass substrate from a solution of cadmium chloride (CdCl₂) and thiourea (NH2CSNH2) with triethanolamine (TEA) as complexing agent. CdS – PbS films were obtained by depositing lead sulphide (PbS) films on the CdS – coated glass substrates from a solution of lead nitrate [Pb(NO₃)₂] and thioacetamide NH₃CSNH₂. Complexing agent again was TEA while in both cases aqueous ammonia (NH₃) created the necessary alkaline medium for the reaction to take place. The energy dispersive X – ray fluorescence (EDXRF) analysis confirmed the composition of the CdS and PbS thin films. Optical measurements were performed with a single-beam UNICAM Heλ 105 Spectrophotometer in the wavelength range of 195nm – 1000nm. The optical transmittance of CdS-PbS films is extremely low, in most cases zero within the UV and first half of the visible region but peaked at 49.4% (at λ = 994nm) for the 150^oC air-annealed samples and at 44.7% (at λ = 994nm) for the as grown samples in the near infra-red region. The absorbance is infinitely large in the UV and first half of the visible regions for both as-deposited films and annealed films, respectively but falls exponentially between the second half of the visible and near infra-red regions. The films have peak reflectance within the visible region. The films showed good characteristics for deployment not only as UV filters but also in solar control coating applications.

Keywords: Chemical bath, CdS, PbS, Thin Films, transmittance.

The relationship between the semi-empirical and the embedded atom model usually employed in total energy calculation .

2015-05-28T15:39:15+00:00

The connection established between the semi-empirical tight-binding potential and embedded atom model was employed to simulate the properties of the fcc metals. The attractive part of the potentials is of the form of the nth power dependence on the effective coordination (or
second moment of the local density of states) instead of the fixed choice of n= ¹/₂ or ²/₃ . The repulsive part of the interaction potential is the standard Born-Mayer type. The model parameter n and four other parameters are fitted, equal to the experimental data for the potential of the specific solid under investigation. The uniquely determined parameter n, is not constant for all metals. In addition, it allows a prediction of the independent elastic constants (C₁₂, & C₄₄) of metals , that are in good agreement with experiments.

Keywords: TB-SMA Scheme , Embedded Atom Method, Semi-Empirical Methods.

Uphole seismic refraction survey for determination of Near subsurface velocities in Eziobodo and its Environs Imo state southeastern Nigeria

2015-05-28T15:36:19+00:00

An uphole survey was carried out in Eziobodo and its environs which are located within the Niger Delta sedimentary Basin. The aim of the survey was to investigate the thickness of the weathering layer (Low Velocity Layer, LVL) and find the velocity trend in the area. A total of 21 upholes were shot. The arrival times (first breaks) of the shots were picked and plotted against the distance. The velocities and the thickness of the weathering layer were computed from the plots. The results show a variation in the thickness of the LVL ranging from 10.4 m to 20.72 m averaging 16.31 m. The velocity of the weathered layer ranges from 472.34 ms^–1 to 796.86 ms^–1 with an average of 623.40 ms^–1. The velocity of the consolidated layer ranges from 1500.62 ms^–1 to 1918.22 ms^–1 with an average of 1743.72 ms^–1. Knowledge of the thickness and velocity of the near surface layers (LVL) could be useful in the oil and gas as well as groundwater explorations. It could also be useful to groups interested in civil or geotechnical engineering.

Keywords: Uphole, Seismic, Refraction

Integrating and Promoting Wind – Tide Energy for Renewable electricity Production and Sustainable Development in Nigeria

2015-05-28T15:36:20+00:00

The continual decline in supply of conventional energy in Nigeria due to the depletion of the national reserve as the demand continued to increase has resulted to energy crisis with epileptic power supply, rising cost of production and food prices and threat to poverty reduction as its effects. Integrating and promoting alternative energy source (wind and tide) is a promising solution to the energy crisis. In this paper, we have shown that integrating and promoting renewable energy utilizing inputs from wind and tidal power will be an effective means of producing electrical power in Nigeria. This will contribute substantially to the federal government programmes to generate more electrical power for the coming decades and will improve the quality of life of the local populace, with a transition towards meeting their basic needs and reducing hunger and poverty– Millennium development goal (MDG 1).

Key words: renewable energy, wind energy, tide, electricity, Nigeria

Apparent Jet Speed as a Function of Distance from the Core in Powerful Radio Sources

2015-05-28T15:36:21+00:00

This paper is aimed at verifying the predictions of relativistic beaming and orientation based unified model for Powerful Radio Sources. Eighty Five (85) quasars and Eleven (11) FRII galaxies were studied. Three radio source parameters: mean radial position R_mas, apparent speed β_app and redshift (1+z) of the sample were statistically distributed. To further reveal the effects of relativistic beaming as a cause of differences observed in radio source morphology, the correlation analyses of the various parameters of the two classes were performed. The result is consistent with the beaming and orientation hypothesis that quasars which are closely aligned to the observer’s line of sight, generally have higher apparent jet speeds and lower radial distances.

Development of a microcontroller - based protective Circuit for a direct current -to- alternating current Converter system

2015-05-28T15:36:22+00:00

In this work, a protective circuit for a direct current (DC) to alternating current (AC) converter system commonly referred to as an inverter have been designed and implemented. The method employed a simple operational amplifier (Op-Amp) circuit wired as a comparator to serve as input into the microcontroller, a NOT AND logic gate also known as NAND gate connected in a shutdown circuit mode to serve as output of the microcontroller, a microcontroller which functions as an interface circuit between the comparator and the shutdown circuitry and a visual display that relays what is happening within the controller to the outside world. Equipment such as automatic voltage regulators, automatic inverter systems and so on make use of Op-Amp to provide safety for the components that make up the device. This paper focuses mainly on the use of Op-Amp in ensuring the longevity of electronic systems; it does this by providing: no-load, low-battery and overload sensing signal to the input ports of the microcontroller. The 80C51 microcontroller which was simulated using Proteus/Mide software package have been used to generate the appropriate output signals required to operate the NAND logic gate wired as a shutdown circuit. With the aid of an external shutdown circuit arrangement, the entire system can be shut down after given a prior warning alarm about all the conditions earlier mentioned above.

Keywords: Op-Amp, Microcontroller, Inverter, Ports, Battery.

Detection and characterization of near surface structures using seismic refraction around Shika, Nigeria.

2015-05-28T15:36:23+00:00

A geophysical investigation was carried out at Shika, using seismic refraction method. The aim was to delineate, map and characterize the different strata of the subsurface within the flanks of a dam. In order to achieve this aim, varying geometric spreads were used with geophone spacings of 5m, 4m, 3m and 2m successively for different traverse on the same profile. The Generalized Reciprocal Method (GRM) results gave average velocities of 1356 ms^-1, 2543 ms^-1 and 4065 ms^-1 for the overburden, weathered basement and fresh Basement, respectively. In some profiles, the model suggests a sedimentary thickness of not less than 20m overlying the Basement. The results showed that as the geometric spread is reduced, the shallow structures within the overburden strata become enhanced. Hence making it possible to recover the velocities of hidden and undetected layers within the overburden and weathered Basement respectively. These overburden deposits consisting of consolidated and unconsolidated conglomerates were identified from the velocity values and correlated with the available borehole log data collected from within the area. In addition, a picture of the subsurface layering was successfully mapped from the refraction results despite the geologically complex environment.

Keywords: Offset distance, Refractor, Forward and Reverse rays, Velocity analysis function, Generalized time depth, Depth sections

A seismic refraction study of the boundary between Bida basin and adjoining Zaria basement complex, Nigeria.

2015-05-28T15:36:24+00:00

The area under study spans a suspected boundary between the Bida Basin and the Zaria Basement complex, Nigeria. The study involves eleven profiles covering an area of about 0.3km². The result indicates that the depth to the refractor varies from 2.3m to 17.4m with an average of 7.7m. This variation indicates the degree of weathering and erosion of the bedrock whose irregular planar subsurface was subsequently filled with large deposits of alluvium forming a thickness as much as 16m. The average velocity of the first layer is 1700 ms^-1, representing a higher presence of dry alluvium, clay and sand in the overburden. The average velocity of the second layer is 6100 ms^-1, which indicates that the basement in the survey area consists of rocks mostly of granite schists, with other volcanic (meta-igneous or igneous) rock. The velocity values ranging from 717.7 ms^-1 to 2000 ms^-1 found on the eastern and western part of the area indicates the presence of thick alluvium deposits (meta-sedimentary) of the Bida basin to the west. This implies that considerable erosion had taken place during oregin event of the Pan-African era. Towards the Zungeru (eastern) part, the thickness reduced to 2.3m indicating that the survey area lies over the boundary between the Zaria basement complex and the Bida sedimentary basin.

Keywords: Basement Complex, Sedimentary Basin, Geologic Boundary, Weathering and Erosion, In-line Refraction profiling.

Integrated geophysical approach in groundwater exploration of WallaB, Gwoza local government area of Borno state, Nigeria.

2015-05-28T15:36:26+00:00

A combined geophysical investigation comprising electromagnetic (EM) and resistivity depth sounding carried out around Gwoza area indicate that the area is suitable for borehole development. The electromagnetic results along six profiles identified five locations that are favorable for detail vertical electrical sounding investigations. These locations with a conductivity range of 28-77 Sm^-1 were further studied with the help of the Schlumberger electrode array. Both manual and computer interpretations of the resistivity survey indicate three geo-electric horizons in the study area. The first horizon is interpreted to be the overburden, a sandy clay horizon with thickness and resistivity values in the range of 0.90 – 1.50 m and 103.3– 320.7ohm-m respectively. Weathered granite consisting dominantly of clayey material is the second geo-electric unit. This unit has a thickness range of 7.20 –14.42m and resistivity of 12.0–20.7ohm-m. The most important hydrogeological horizon in the study area is the third horizon demonstrated by fractured granites. This is also the geo-electric basement for the maximum current electrode separation attained during the survey. Its resistivity is between 342.6 – 652 Ohm-m. As a result of the thickness of, and the low clay content of the third geo electric horizon, the authors recommend all the VES stations for future borehole location in the area.

Keywords: Electromagnetic Survey, Resistivity technique, Groundwater, Basement Complex.

Magnetic Analysis to Determine the Permeability of a Geothermal Reservoir: Case Study of the Ikogosi Warm Spring Area, Ekiti, South-Western Nigeria.

2015-05-28T15:36:27+00:00

Aeromagnetic data over the Ikogosi geothermal system is analyse to determine the reservoir permeability of the area. Data along fifteen profiles allowed detailed analysis of the hydrothermally demagnetized rocks thought to represent the extent of the geothermal reservoir. The study shows that demagnetized rocks has good correlation with reservoir permeability. Accordingly, the geothermal reservoir has been delineated. This analysis suggests that demagnetized rocks are mainly associated with high permeability in a geothermal system.

Keywords: Aeromagnetic, Geothermal, Permeability, Magnetization

Rotation Measure Distribution in Compact Steep-steep Spectrum Sources

2015-05-28T15:36:28+00:00

We have used radio polarization data at different frequencies to obtain the rotation measure, RM, the source rest frame rotation measure, RM(1+z)² and the spectral index, α in a sample of Compact Steepspectrum Sources (CSSs). The CSS quasar sub-sample has RM(1+z)² median values of ~-15.01 and 14.13 for the jet and counter-jet sides respectively, while corresponding values for galaxies are ~ -3.23 and 5.86. Spectral index asymmetry was also found with median spectral index values of ~1.11 and 1.50 for the jet and counter-jet sides of the quasar sub-sample, and the galaxy sub-sample has corresponding values of ~0.95 and 1.23; while there is no significant correlation between rotation measure and spectral index. The asymmetries observed could be due to a combination of both intrinsic and orientation effects.

Keyword: Rotation Measure, Compact Steep-spectrum Sources, Galaxies, Quasar and Spectral Index.

Results for equispaced level conduction band quantum well (QW) with some ternary alloys, A_xB_1-xC.

2015-05-28T15:36:29+00:00

The detail procedure for the calculation of equispaced level QW in the conduction band of semiconductor heterostructures is given in Ejere and Idiodi, 2011. This article contains results for equispaced level design in the conduction band of three very useful ternary alloys, which might be of interest to Experimentalist and Industrialist.

Keywords: Quantum well, conduction band, Equispaced Levels and Ternary Semiconductor Alloys.

Properties of Chemically Synthesized Nanostructured Copper (II) Oxide Thin Film

2015-05-28T15:36:31+00:00

Wet chemical method has been successfully used in preparation of Copper (II) Oxide Thin Film by spin coating on glass substrates, at an annealing temperature of 600°C for 1 hour in air. It has high absorbency within visible region wavelength 400 – 700 nm of the electromagnetic wave, making it a suitable absorber in the fabrication of solar cell. The direct energy band gap was estimated using Tauc’s relation to be 1.54 eV. The cupric phase synthesized was confirmed by matching the 2θ peak values obtained 35.23° and 38.37° with the JCPDS value and observed to have a monoclinic lattice system. The morphology as revealed by the scanning electron microscope image shows a uniform round shaped grains. The average grain size was obtained using Debye scherrer formular to be 24.72 nm. The broad peaks observed on the X-ray diffractometer pattern shows that the grains are very small: nanostructured in nature.

Keywords: Thin Film, Band Gap, Nanostructure, Grain Size, Synthesized and Crystalline.