ABSTRACT The factors that affect the colour yield of an acid dye on nylon fabric were investigated at a constant temperature of 500C, usingC.I. Acid Yellow 23,with citric acid and sodium chloride as auxiliaries. It was observed from the absorbance results that the colour yield of C.I. Acid Yellow 23 improved with increase in time of dyeing, while the absence or increase beyond 1% (acid) and 5% (salt) reduced the colour yield of the acid dye on the nylon fabric. Also, at a constant dyeing tim...
ABSTRACT Experimental investigation of anaerobic digestion of the organic fraction of municipal solid waste (MSW) in an upflow bioreactor with central substrate dispenser (UBCSD) is presented. The UBCSD consists of two similar size bioreactors joined by a central substrate dispenser (CSD). The UBCSD is a component of an integrated system of bioreactors also containing the upflow anaerobic sludge blanket (UASB) reactor and the continuous stirred tank reactor (CSTR), assembled systematically t...
ABSTRACT The teaching of Business Studies, overtime has been recording below average performance in the national examinations all over the world, Kenya inclusive. Studies carried out in some other part of the world clearly document the reasons for this and the measures that have been undertaken to alleviate this problem. This study sought to investigate the pedagogical challenges facing the teaching of Business Studies subject and their impact on students’ achievements in national exa...
Abstract Phase Change Memory is one of the most promising concepts for the future generations of Non Volatile Memories. Extensive work is nowadays performed on the Phase Change Materials to optimize the cell properties for specific applications. In particular, for the embedded memory market, it is desirable to reduce the writing current while raising data retention capability. In2Se3 has shown remarkable characteristics for phase change random access memory (PRAM) applications. Among the rema...
BSTRACT A solar cell is a device that converts light energy into electricity by photovoltaic effect. The photovoltaic effect refers to photons of light exciting electrons into a higher state of energy, allowing them to act as charge careers for an electric current. Materials presently used for solar cell fabrication include silicon, gallium arsenide (GaAs) among others. However, these materials are expensive and not readily available. As a result, there is need to search for alternative mater...
ABSTRACT The desire for smaller, more efficient and faster semiconductor devices has made the design of the Schottky devices, material preparation and characterization very vital. There is little research if any on the effect of Schottky contact geometry on I-V characteristics. In this study various circular and rectangular thin filmed Al/ZnSe Schottky diodes were designed by varying; the shape, area of the Schottky contact, the inter electrode distance and thickness of the thin film ZnSe. F...
ABSTRACT In this work, SnO2 thin films were deposited on a glass substrate by spray pyrolysis technique using aqueous solution of tin (IV) chloride (SnCl4.5H2O) dissolved in ethanol. Different types of thin films such as SnO2, F: SnO2, Pd: SnO2 and Pd-F: SnO2 were deposited at a substrate temperature of 450 0C. Post deposition treatment: annealing and passivation were performed in a tube furnace at 450 0C. The samples, both as prepared and treated, were thereafter characterized by optical and...
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, ...