ABSTRACT Optical spectroscopy is a non-destructive and contactless method for characterizing optical and electrical properties of thin films; reflectance, transmittance, refractive index, permittivity and band gap. These properties determine the application of a thin film as a polarizer, laser, solar cell or photodiode among others. To measure accurately optical properties of thin films, the common types of optical spectrometers used are ellipsometers and spectrophotometers. However these ins...
ABSTRACT Chalcogenide phase change memory is a potential replacement to flash memory due to excellent properties such as high storage density, rapid phase transition and archival stability. Phase change non-volatile semiconductor memory technology is based on an electrically initiated, reversible rapid amorphous-to-crystalline phase change process in multicomponent chalcogenide alloy materials similar to those used in rewritable optical disks. For over a decade Ge2Sb2Te5 (GST) compound has be...
ABSTRACT Information Communication Technologies (ICTs) have become the fundamental pillars of the modern society today. They have brought along a lot of changes, many of them deep-seated, in almost all the aspects of societal functions and services. Just like any other field, the field of education has been greatly influenced by advancement in technology. Ultimately this has led to changes in teaching, learning and research. Despite the potential that ICTs have in enabling and enhancing a tea...
ABSTRACT Solar energy which is a free and abundant form of energy has the potential to provide sufficient power to the growing number of industries and population especially in the developing world. Its maximum exploitation has however been hindered by the high cost of silicon based solar cells which currently dominate the market. It has been reported that copper based thin film solar cell technology is known to be 40% cheaper than silicon based solar cells. In order to effectively exploit s...
ABSTRACT Energy crisis occasioned by a decline in the availability of fossil fuels and increasing carbon dioxide emissions that are causing global warming has enhanced interest in the development of clean and renewable sources of energy. Solar energy has a great potential of meeting a large fraction of energy needs using photovoltaics. While most PV cells in use today are Silicon-based, cells of other semiconductor materials have been manufactured. Considerable research has been focused in se...
ABSTRACT Phase change materials have been widely used in optical and electronic storage due to rapid and reversible phase transition between amorphous and crystalline states with remarkable resistivity and optical contrasts. More recently these materials have been identified as suitable candidates for phase change random access memory (PCRAM) applications due to their potential for high scalability, low power and fast speed operation. Despite these superior properties and enormous potential, ...
Abstract In this research an n-type CdxZn1-xS and p-type PbS thin films were optimised for solar cell applications employing chemical bath deposition technique. The thin films were prepared using thiourea and nitrates of cadmium, zinc and lead. Deposition of optimised CdxZn1-xS was done by CBD at 820 C and in alkaline conditions while that of PbS was done at room temperature and both films at normal atmospheric pressure utilizing aqueous conditions. This study concentrated on optimising...
ABSTRACT The Energy - Exergy based performance analysis of the Solid Adsorption Solar Refrigerator is presented. The system comprises the collector/generator/adsorber, the condenser and the evaporator. It utilizes activated carbon/methanol as its adsorbent/adsorbate working combination. The exergy performance analysis of this refrigerator involves detailed assessment of all the following sub-processes that make up the refrigeration cycle, which are isosteric heat-up phase, desorption phase, ...
Abstract Effects of liquid holdup on hydrocarbon production in tapered tubing string using Niger Delta fluid properties was undertaken in this work. Oil reservoir fluids flow to the surface as a multicomponent fluid in pipes during production. Multiphase flow occurs due to the density of different phases involved in reservoir fluid and each fluid phase flow at different velocity. In this study, analytically developed equations and existing fluid correlations were used for determination of pr...
ABSTRACT The effect of cooling rate and modification on the microstructure and tensile properties of Al-Si-Mg alloys was carried out. Castings were produced using a stepped pattern that has different section thicknesses. Sand casting technique was used. A thermocouple inserted into the mould cavity recorded the cooling rates for the different sections. The Al5.43%Si3.83%Mg which was melted in the crucible furnace was modified with sodium (Na) and strontium (Sr) in separate cases. The molten ...
ABSTRACT The purpose of this study is to develop an innovative technique for optimized gas lift design for marginal fields of the Niger Delta. This study used well data from mature fields located southwest of the Niger Delta to develop optimized gas lift design techniques using the single point continuous gas lift approach. A total of fifty-nine (59) wells from the fields were selected for preliminary screening as potential gas lift candidates. The screening process involved; reviewing well ...
ABSTRACT The dynamic simulation is one of the key steps in the validation of the design process of the motor drive systems and it is needed for eliminating inadvertent design mistakes and the resulting error in the prototype construction and testing. A quality mathematical model of induction machine based on the dynamic equations and D-Q transformation technique is presented in rotor reference frame and a computer simulation of a 7.5kW three phase induction motor was carried out based on thi...
ABSTRACT In the design of flood control structures, there is need for rainfall intensity estimation for design discharge computation. To make the rainfall intensity values easily available in south-east and south-south Nigeria, this research developed rainfall models. Dimensional and Regression analyses were used to produce models of rainfall intensities. The dimensional models are dimensionally balanced as opposed to the other models which are based on Talbot, Benard and Quotient equations....
ABSTRACT Simplified predictive numerical models have been developed for diffusion rate of crude oil spilled into Niger Delta soils. The proposed model equations were developed using Fourier transformation, and Green’s function. The induction principles as well as the indicial matrix method of dimensional analysis were adopted in determining the functional parameters that could possibly influence their diffusion rates. These mathematical models correctly predict one – dimensional longitud...
ABSTRACT New Biodegradable drilling fluids were developed using Brachystegia eurycoma (achi), Detarium microcarpum (ofo) and Pleurotus (osu). The drilling properties such as yield point, apparent viscosity, low shear rate yield point and fluid loss were determined.The field polymer muds that are currently in use namely; PAC-R and PAC-L were formulated and used as control samples to the new proposed product. Herschel –Buckley model was used to obtain the yield stress. Cutting transport rati...