ABSTRACT Density functional theory (DFT) is a useful theoretical and computational tool for electronic structure calculations, which form the basis for the classification of materials into conductors, semiconductors or insulators. DFT started with a crude approximation by Thomas and Fermi (TF theory) which calculated the kinetic energy of electrons using the so-called local density approximation (LDA). Although TF is computationally inexpensive, it provides a poor numerical result due to a la...
ABSTRACT The study of the structures and properties of organic materials for organic photovoltaic (OPV) applications and their interrelationships is a rapidly growing field of research, involving interdisciplinary efforts at the frontiers of chemistry, solid state physics and materials science. These materials differ from the better-understood silicon solar cell based materials by the lack of long range three-dimensional translational periodicity in their atomic arrangements and also by their...
ABSTRACT In this study, Flexy energy analysis taking exergy analysis and heat recovery into account on performance has been performed. The effects of wasting heat on exhaust gas temperature and cooling engine, is analysed in terms of design paramèters. It was observed that thermal exergy from a wasting heat for Flexy energy might be used to produce cold. In the theoretical study, the achievement of heat recovered is to circulate water through the source of exhaust gas. It was found that the...
Abstract The complexity of the microstructure of the active layer in organic photovoltaics (OPVs) poses a unique challenge in improving the efficiency of OPV devices. Molecular dynamics (MD) simulation provides a direct route to determining this microstructure. However, for a donor material like poly (3- hexylthiophene), (P3HT)n, approximations made in all previous force field for MD simulation has been the neglect of explicit polarization. We looked at the morphology of (P3HT)n using MD sim...
ABSTRACT The high temperature superconducting cuprates show some non Fermi liquid behaviour in their normal state. Also there is no generally accepted theory of high temperature superconductivity. The BCS theory has failed to explain the superconductive state properties of the cuprate superconductors. GorterCasimir two uid model and London theory has been very useful before the BCS theory. Varma and his co-workers propounded a `marginal` Fermi liquid theory which explains the normal state pro...
ABSTRACT The advent of nanotechnology together with Biomedical Microelectro-Mechanical Systems (BioMEMS) for improved efficacy in treatment of cancer has resulted in the development of an implantable biomedical device for localized hyperthermia and drug delivery. This thesis work develops a mathematical framework based on relaxation losses of heating mechanism of magnetite magnetic nanoparticles synthesized with the Polydimethylsiloxane (PDMS) gel encasement. Numerical solution of the mathem...
A feasibility study of a conceptual nuclear design of a facility capable of producing high thermal neutron fluxes using isotopic neutron sources in a multiplying medium was carried out. The one-dimensional multigroup neutron diffusion equation was solved using the finite difference technique. A computer code SUNDES was written in FORTRAN 77 programming language and used to study the effect of reflectors, shielding materials and strength of isotopic neutron sources on the production lev...
ABSTRACT A popular model that have been used to study ferromagnetism is the Ising Model which is an arrangement of spins along a particular direction and with discrete values of +1. 1-D Ising model doesn't show a phase transition to the paramagnetic phase as opposed to the 2-D Ising model which shows a transition at a critical temperature. In this work, I have used Monte Carlo simulation method to study the 1-D quantum Ising model in a transverse eld at a nite temperature to obtain the critic...
ABSTRACT This research investigates the effects of bending on the electrical, optical, structural and mechanical properties of flexible organic photovoltaic (OPV) cells. Bulk heterojunction organic solar cells were fabricated on Polyethylene terephthalate (PET) substrates using Poly-3-hexylthiophene: [6, 6]-phenyl-C61-butyric acid methyl ester (P3HT: PCBM) as the active layer and Poly (3, 4-ethylenedioxythiophene) Polystyrenesulfonate (PEDOT: PSS) as the hole injection layer. All the organic...
ABSTRACT Organic-inorganic hybrid perovskite solar cells have attracted great attention in the photovoltaic research community in recent years due to its ease of processing, low cost of production, superb light-harvesting characteristics, and relatively high efficiency which make it more preferable over other existing solar cell materials. Lead-based perovskites (CH3NH3PbX3, X= Cl, I, Br) solar cells have recently attained a high efficiency of ~19.3% which far surpasses the efficiencies of m...
Abstract In this work, we review 3-dimensional gravity by canonically analyzing the Hilbert- Palatini action. We apply a time gauge used in 4-dimensional loop quantum gravity [14] to the simpler case of the 3-dimensional loop quantum gravity. By time gauge xing this Hilbert-Palatini action it leads to the Gauss constraints, the spatial dieomorphism constraints, the Hamiltonian constraint and a new constraint C. The gauge symmetries generated by this new constraints are spacetime dieomorphism ...
ABSTRACT The erodibility of soils from six different rainfall erosivity areas in Ghana were investigated. The soils were sampled and packed into wooden boxes maintained at 9% slope. Soil erosion was measured by applying simulated rainfall storms over the soil samples. The erodibility factor K for each soil type was calculated from USLE, K=A/EI30LSCP. The results showed a variability in erodibility factor values which ranged from 0.36 to 0.62. The physical and chemical properties of the soils ...
ABSTRACT In this work the potential of harnessing electricity from solar and wind sources in Ghana is evaluated both quantitatively and qualitatively. In this regard solar, wind and other relevant data were collected (over a period of one year) from various parts of Ghana. Detailed assessment of the capacity or potential of power production from hybrid solar-wind sources is done with the use of empirical mathematical formulae and the PRO VITUS model incorporated in the ‗ENERGY X‘ software...
Abstract The Maxwell equations of electrodynamics acquire an additional symmetry if one assumes the existence of hypothetical particles-magnetic monopoles, carrying a magnetic charge. The additional internal symmetry is the electromagnetic duality generated by the rotations in the space of electric and magnetic charges. In this project we revise the electromagnetic duality in his global aspect starting with the celebrated Dirac monopole, a singular solution in a slightly modified Maxwell the...
Abstract Femtosecond lasers represent an electromagnetic field with field intensities approaching and even exceeding atomic binding field. When irradiated on a target, the material responses change from linear to nonlinear within a very short time. In most situations nonlinear absorption dominates and can be used in micromachining of materials. In this work, analytical formulae are outlined relating laser and target parameters. This permits prediction of ablation conditions of materials. Ion...