ABSTRACT A year-long campaign that accounted for seasonal differences have been conducted to examine the levels, chemical composition and sources of ambient particulate matter in multiple neighbourhoods of varying socioeconomic status in Accra, Ghana. Between September 2007 and August 2008, simultaneous measurements of PM2.5 and PM10 aerosols at five monitoring sites in four neighbourhoods (Asylum Down, East Legon, Nima and James Town/Ussher Town) were done for one 48-hour period every six d...
Abstract Graphene is an effectively two dimensional form of carbon atoms arranged in honeycomb lattice. Due to its lightweight, high electron mobility and other special electronic properties it is considered both an academically interesting and industrially promising candidate for various electronics applications. Many investigations focused on graphene require theoretical simulations to be performed over a large number of unit cells of graphene. For simulation scenarios where ab-initio meth...
Abstract We present theoretical results of the study of H2S adsorption on gold cluster Aun(n = 1, 5) using density functional theory with PerdewBurke-Ernzerhof (PBE) exchange-correlation energy functional. Minimum energy structures of the gold cluster along with their isomers are considered in the optimization process. H2S molecule is observed to adsorb on to the gold cluster. However, the adsorption energy decreases with increasing cluster size. The structure of the gold clusters are simila...
Abstract Most anticancer drugs are polar, cytotoxic and have complicated structures which cause difficulty in their penetration through the cell membrane. This presents a serious problem in chemotherapy. Is it possible to use carbon nanotubes (CNTs) as intracellular drug delivery agents to concomitantly mininmize side effects and maximize therapeutic effect? Although previous experimental and simulation studies have demonstrated that CNTs are able to translocate through cell membrane, the ce...
ABSTRACT In general, it is assumed in some non viscous flows that the flow velocity is constant at a cross-section. In this thesis, If we impose more realistic boundary conditions by, for example, introducing viscosity,and suction at walls, the net mass flow will change since the continuity equation must hold. The convective acceleration terms will be products of variables such that a nonlinear behavior will take place in the flow. The work will consist of deriving all the equations and param...
ABSTRACT This thesis deals with the control of non linear oscillations in plasma governed by a classical Van der Pol equation . The main interest devoted to such an investigation is that non linear oscillations in plasma is essential in industry. In chapter 1 , we present some generality on the dynamical systems . Chapter 2 is focussed on the analytical study of the Van der Pol equation in autonomous regime . The amplitude and the phase of the stable limit cycle are derived using the Averagin...
ABSTRACT Solar radiation is the ultimate source of energy for the planet. To predict the values of temperature and instant solar radiation when equipment are not readily available from obtained equations, a good knowledge and understanding of the disposition and distribution of solar radiation is a requirement for modelling earth’s weather and climate change variables. A pyranometer (CM3) in series with a PHYWE amplifier and a voltmeter were experimentally set up and used to study the amou...
ABTRACT Instrumental Neutron Activation Analysis has been applied in the multi-element analysis of five soils from three agro-ecological zones in Ghana, using the Single Relative Standardization Method. The analysis was carried out at the Ghana Atomic Energy Commission Research Reactor-1 (GHARR-1) Centre. Concentrations of 34 elements in deciduous forest, forest and Coastal Savanna soils were obtained. Elemental compositions and their levels in the five soils; Oda ,Bekwai, Toje, Akuse and An...
ABSTRACT This work shows the increase in surface dose caused by thermoplastic immobilizing masks used for positioning and immobilization of patients. Thermoplastics are organic materials which soften when they are heated. They can be formed after softening and retain their final shape when cooled. The use of these thermoplastic masks are relevant during patient treatment. However, it can lead to an increased skin dose. Measurements were done at source-to-suface distance of 80 cm for external ...
ABSTRACT Corrosion of mild steel used in industrial and engineering enviroments has posed a serious problem in the society. Hence, this research investigated the effects of ethanol, water and sulphuric acid extracts of Solanum melongena(SM), (garden egg) and Chrysophyllum albidum (CA), (sherry) on the corrosion of mild steel in I M HCl and 0.5 M H2S04 solutions using gravimetric and electrochemical techniques. The results obtained indicated that all studied plant extracts were adsorption typ...
ABSTRACT In this research work a low pressure steam turbine was designed, constructed and tested for the purpose of studying how electrical power can be generated using low pressure steam from concentrated solar power (CSP) sources. The turbine consist essentially of a two cylindrical casings to which stationary blades are fixed on the inside and a shaft carrying rotating blades (rotors) penetrating between the rows of stators. Steam fed into the turbine passes alternately through the stator...
ABSTRACT The effectiveness of the water shield above the core and in the pool for shielding gamma rays and neutrons was investigated by measurements and calculations for a tank-in-pool type reactor, Ghana Research Reactor-1, GHARR-1. Experimental determination of y - dose rates were made using Radiation Alert Monitor-4 and halogen counter type J613 y probe with readout on y -radiation monitoring system of the control console and the microcomputer control system. The PC version of the one-dime...
ABSTRACT In this work, the production of biogas from local biomass has been studied through the design, construction and operation of a single-stage, multi-feedstock anaerobic digester, with the aim of providing the scientific and technological bases for the mass assembly and deployment of modular and scalable bio-digester system, using components obtainable in Ghana. A horizontal cylindrical plastic tank (1 m3) with torispherical ends has been developed into an air-tight (sealed) anaerobic d...
ABSTRACT During radiotherapy, some accessories used gets into the path of the photon beams. These somehow attenuate the beam to some extent. Therefore it is imperative that every radiotherapy facility quantifies the degree by which these accessories attenuate the beams. This informs the facility operators on the necessary corrections to make to achieve the desired dose to the target area. The purpose of this study was to evaluate the attenuation effects of 6 MV and 15 MV photon beam by an iBe...
ABSTRACT This project involves a design of sun tracker for PV system. The circuit of the sun tracker is designed in such a way that it follows the track of the sun as it travel in the sky. The LDR are connected to noninverter input of the operational amplifier whose reference voltage resistor R1 and R2 is 10Ω each. At the output of the operational amplifier are NPN and PNP transistor. These transistors are used to drive the DC motor in forward and backward directions which corresponds to t...