Abstract Pristine and transition metal (Fe, Mn, Co and Ni) doped ZnO powders were synthesised us- ing a hydrothermal method, and characterised by x-ray powder diffraction, ultraviolet-visible absorption spectroscopy, and photoluminescence (PL) emission spectroscopy. Synthesis was carried out at pH 3 and pH 5, and the powders annealed at 280 ◦C and 600 ◦C. Doping was done at concentrations of 1, 2, 4 and 8 mol %. Computational studies were also carried out on undoped and transition metal (...
ABSTRACT Microwave signal attenuation due to harmattan and rainfall are two of the major constraints in selecting microwave bands in Ghana. With customer complaints of signal loss during these seasons, telecommunication companies compensate for sudden losses in signal strength by amplifying the signal wave. This study investigates the effect of harmattan and rainfall on communication link for frequencies ranging from 10 to 100 GHz for two locations in Ghana, namely Axim and Tamale. Visibility...
Abstract This study concerns the application of a model-based approach for problem solving and conceptual understanding, in the context of kinematics, relating to the “foundation” component of an introductory physics course designed for students who are academically and scientifically underprepared. A new method for portraying objects in motion, “freeze frame” representation, was introduced. The particular visual conceptual model was employed as a representational bridge for translati...
ABSTRACT Refractive index is an important optical parameter that exhibits the optical properties of materials. Single-Diffraction Method (SDM) and Abbe’s Refractometer Method (ARM) have been used for the measurements of refractive indices of twelve water samples collected from different surface water sources in Namibia. SDM employs a diffraction grating, rectangular glass cell and Ne-He laser emitting a monochromatic light of 632.5 nm. Refractive indices of water samples were measured with...
ABSTRACT Aeromagnetic data of Nsukka and Udi areas were analyzed qualitatively and quantitatively. The study was aimed at mapping mineral deposits in a sedimentary basin, delineating susceptibility of rocks in the area, dip, plunge and type of body causing the magnetic anomaly and their trends as well as estimating the depth to magnetic source bodies. Spectral Analysis, Source Parameter Imaging (SPI), and Forward and Inverse modelling methods were used in the quantitative interpretation...
INTRODUCTION The physics design of nuclear reactors requires the determination of the gross statistical behaviour of the neutron population in the reactor system. This in turn calls for the solution of the Boltzmann equation of neutron transport theory which forms the subject matter of reactor theory. It is however not easy to solve this equation by a direct discretization process even on the largest computers because of the presence of too many independent variables, complicated energy varia...
ABSTRACT Gravimetric, reflectometric and elemental analyses have been carried out on airborne particulate matter sampled in a semi-rural area of Kwabenya, near Accra-Ghana. The PM 10 aerosols were sampled using a Gent sampler, size segregating the aerosol into coarse (PM10.2.5) and fine (PM2.5) fractions. The data and derived information were generated from 216 days of sampling spanning a period of about 14 months, 28th December 2005 to 12th February 2007. The particulate matter (PM) at Kwab...
ABSTRACT Lightning is an important component in the global electric circuit of the earth. It is a leading cause of outages in electric power and telecommunication systems, of forest fires and of delays in aircraft missions. A lightning sensor operating at a radio frequency of300 kHz was constructed ~d used to study the occurrence of lightning in and around the University of Ghana campus during thunderstonns. Rainfall figures during each thunderstonn were also recorded. Data was collected ov...
Abstract Key to Escherichia coli (E-coli) bacteria survival is its ability to direct its movement to greener pasture and flee harmful environment - also known as chemotaxis. This thesis focuses on the modelling of E-coli chemotaxis in twodimensions with emphasis on trying to understand the basic physics of how such a tiny microswimmer swim up a concentration gradient despite the enormous thermal fluctuations in its environment. E-coli strategically employs near straight swimming (also known ...
Abstract The power conversion efficiency of perovskite solar cells has risen from as low as 3.8% to as high as 19.3% in just five years with yet a projected value of over 20% in the next few years by experimentalists. Such a tremendous breakthrough is one of its kind in photo-voltaic research with thin film solar cells as the only major competitor. The light harvesting layer in these new devices has a crystalline structure called the perovskite structure which is capable of absorbing photons...
Abstract The thesis presents the modeling and simulation of three types of lasers namely; Semicondoctor laser, Solid state laser and CO2 laser. The rate equations were derived and simulated to examine the dynamic behaviour of the three types of lasers under investigation. The result shows that the Semicondoctor laser has the longest latency period, highest intensity spikes and takes a longer time to come to relaxation oscillation (RO) while the CO2 laser has the shortest latency time, the lo...
Abstract Not too long ago(2008),a new pnictide Superconductor free from arsenic was discovered –LiFeP. It belongs to the family of the so called ‘111’ type iron Superconductor. It has unique characteristics in its normal state which can be useful in understanding the unusual high temperature superconductivity observed in iron pnictide compounds. In this work,we studied LiFeP from first principles. The structure was optimised,electronic structure calculations were performed yielding lat...
ABSTRACT This work presents the responses of optical properties and mechanical failure of layers of stretchable organic electronic structures under tension using analytical, simulations, and experimental techniques. The interfacial contact around dust particles was modelled. The deformation induced during stretching was also modelled before simulating the stress distributions and calculating the crack driving forces of the layers using finite element analysis. The finite element simulation o...
ABSTRACT An effect that is observed when an electron passes through a non-collinear magnetic textures such as skyrmion, the electron gets deviated as a result of the fictitious magnetic field generated by the skyrmion giving rise to Topological (spin) Hall effect. our interest is on the effect of disorder (magnetic and non-magnetic) on transport of non-trivial topological textures. In these work we carry out a thorough study of the topological Hall and topological spin Hall effects and test t...
Abstract This work presents numerical calculation of electromagnetic waves in unidirectional on-chip silicon optical diodes. An original optical diode, designed by Wang et. al. [Opt. Express. 19, 26948-26955 (2011)], is based on breaking of spatial inversion symmetry and the directional band gap difference of two 2D photonic crystals comprising a hetero-junction structure. The dimensions of our structure are however different from those of Wang et. al. The electromagnetic waves in the diode ...