Research Papers/Topics in Physics

Estimation of Developed Reserves in Gas Lifted wells.

Abstract Reliable estimates of petroleum reserves are invaluable in reservoir management decisions and economic evaluation. Classical decline curve analysis techniques have been routinely used and are generally accepted in the industry to reliably estimate developed reserves up to a predetermined economic limit qec in oil wells. However Decline curve analysis techniques are based on the assumption that past production trends and their controlling factors will continue in the future and theref...

Investigating Electronic Pedestals Of The Analogue Front-End Boards Of The Upgraded High-Energy Stereoscopic System (H.E.S.S-I) Cameras

Abstract The High-Energy Stereoscopic System (H.E.S.S.) is an array of five imaging atmospheric Cherenkov telescopes located in the Khomas Highland in Namibia, dedicated to very-high-energy (VHE, 100 GeV – 100 TeV) gamma-ray astronomy. It consists of four identical 12 m diameter telescopes (H.E.S.S.-I) which started operating in 2003 and a large 28 m diameter telescope (H.E.S.S.-II) which was brought online in 2012 [1]. The H.E.S.S.-I camera upgrade project was aimed to increase the stabil...

Groundwater Velocity Field: Stochastic Analysis Of Major Groundwater Flowpaths And Implications For Contaminant Transport Within The Ga East And Adentan Districts, Ghana

ABSTRACT The hydrogeological system of the Ga East and Adentan Districts of the Greater Accra Region of Ghana was studied using numerical modelling on the Groundwater Modelling System platform (version 10.0). Historical hydrogeological data and groundwater monitoring data on twenty wells drilled in 2012 were relied on in conceptualising the hydrogeological system of the study area. A single aquifer system made up of quartzite-schist formation was identified. The borehole logs reveal four lith...

Experimental and Computational Study of Transition Metal Doped Zinc Oxide.

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 (...

The Effects Of Harmattan Dust And Rainfall On Microwave Signals In Parts Of Ghana

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...

Measurement And Comparison Of Refractive Index Of The Water Samples Collected From Different Surface Water Sources In Namibia

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...

Characterization And Sources of Air Particulate Matter at Kwabenya, Near Accra, Ghana

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...

Stochastic Modelling Of A Chemotactic Microswimmer

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 ...

Limiting Efficiency Of Perovskite Solar Cells

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...

Fundamentals of Laser Dynamics

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...

Calculations Of Phonons And Phonon Dispersion In LifeP Pnictide Superconductor

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...

Effects Of Stretching On Flexible Organic Electronic Structures

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...

Effect Of Disorder On Spin Transport In Topological Non-Trivial Magnetic Textures

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...

The Design Of An On-Chip Silicon Photonic Diode

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 ...

Simulation Of Carbon Nanotube Growth

ABSTRACT The basic understanding of the underlying techniques of growing Carbon Nanotubes (CNTs) with a specific chirality is still obscure and needs to be understood so as to properly harness its potentials. Using both Classical Molecular Dynamics (MD) simulation with empirical force fields and a geometry optimization based on ab initio forces, we show that the dynamics involved in the growth of CNT on iron nanoparicles is non linear but complex. For a good geometry, the growth depends on t...


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