ABSTRACT Radioactive elements are found everywhere in the environment. Detectable amounts occur naturally in soil, rocks, water, air and vegetation and may be ingested if they enter the food chain, or, inhaled. Inhaled and ingested radionuclides lead to internal exposure. In addition, humans also receive external exposure due to the radioactive materials located outside the body. Primordial radionuclides 238U, 232Th and 40K are the main sources of external radiation exposure to the general pu...
ABSTRACT Cosmic ray muons are produced by the interaction of primary particles with nuclei in the upper parts of the atmosphere. The charge ratio of cosmic ray muons is the ratio of the number of positive muons to negative muons. It gives valuable information on the hadronic interaction processes in the atmosphere such as the mass of the primary particle. The value of the cosmic ray muon charge ratio has been measured by several experiments to be 12766±0.0032 (the CMS detector), 1.374 ± 0....
ABSTRACT Throughout their lives, human beings are continually exposed to radiation from terrestrial radionuclides particularly 40K, 238U, 232Th and their decay products. The radiation, usually in the form of gamma rays and alpha particles, is largely attributed to building materials for instance rock and concrete mainly used in developed countries and cities around the world, or soil which is principally used in most parts of rural Africa. Radiation exposure from terrestrial sources may be m...
Abstract Digital signal transmission with its high level of immunity to signal impairments has found a wide application in communication. With the much benefits to the government and consumers, digital migration came forcefully by June 2015 inspired by analogue regime limitations. However, the shift came with its challenges with high rate of unemployment, high cost of living and inflation levels in Kenya. Most people are struggling to acquire the costly compliant digital TV sets or buying th...
ABSTRACT Heavy metals are gradually being added into water resources due to the rise in Municipal, industrial and agricultural activities. The fate of heavy metals being in water systems is mainly controlled by transport processes. Transportation of heavy metals by rivers can be both as metal in solution and adsorbed to suspended solids. A one dimension environmental model has been developed in this work to simulate the transport of heavy metals discharged into a riverine system. The model h...
ABSTRACT White light emitting diodes (wLEDs) is considered as the next generation of white light sources after fluorescent lamps due to their merits of long term operational lifetime, high quantum efficiency, energy savings, compactness and environmental friendliness. Presently, cerium-doped yttrium aluminium garnet, Y3Al5O12:Ce3+ phosphor is used to convert blue light emissions from InGaN to white light. However, the emitted white light has low color rendering property due to weak red emiss...
ABSTRACT Nickel doped tin oxide and tin monoselenide thin films were coated using spray pyrolysis. Nickel doped tin oxide Precursor solution was prepared using a 0.05M Tin (II) Chloride (SnCl4.2H2O) and 0.05M Nickel chloride 6-hydrate (NiCl2.6H2O) in de-ionized water and then being added in ethanol in the ratio 1:1 to get equal proportions, followed by about 2-3 drops of hydrochloric acid. Doping tin oxide was done using uniform concentration of (NiCl2.6H2O) of 0-10 %. Precursor solution of t...
ABSTRACT Homa Hills geothermal prospect is located on the Nyanzian rift west of the Kenyan rift system. The manifestation of hot springs and steaming grounds in the area has revealed its geothermal potential. In order to fully asses the potential of this field, the heat source which is one of the main features of a geothermal system had to be properly located based on its perturbation on the gravity field. This enables gravity technique which is a high precision method for measuring density c...
ABSTRACT Background radiation from natural sources is the major source of external dose in our environment. The major radionuclides responsible for this are 40K, 232Th, 238U and their products of decay. Beach sands are weathering resistant residuals of geological formations which gets to the beach by erosion from mainland or deposition through waves and current action from the ocean. Waves wash back lighter grains leaving behind heavy ones which may be rich in minerals such as zircon, ilmenit...
Abstract The danger of aerosols loading in the lower atmosphere of West Africa is a source of concern both at the short or long term. Currently, there are about 45% available data sets over West Africa; hence, it is difficult to ascertain the level of threat that life forms in this region would be exposed to in the nearest future. In this thesis, it was proposed that the current challenges bedevilling the functionality of measuring devices are more of systemic error than design error. The ai...
Abstract Two types of liquids (water and ethanol) are used to investigate the volumetric change of these liquids with change of temperature in order to find the temperature coefficient for both liquids to relate the volumetric change with global warming. It reveals great agreement with theoretical consideration. So the volume of these liquids increased with increases of temperatures.
ABSTRACT In this thesis, we have designed a shielding system consisting of dual layers to shield fast neutrons. Monte Carlo simulation code (MCNP5) was used to simulate the spectra of 252Cf-neutron source and to verify the performance of several moderating materials and absorbers as well. The performance of high density polyethylene (HDPE) as moderating material was examined against different thermal neutron absorbers such as; borated polyethylene (BPE), Boric acid (H3BO3) and Boron carbide ...
Abstract Noble metals nanoparticles are considered as promising material due to their unconventional characteristics owing to several technological applications. Their small size and large surface to volume ratio as compared to their bulk form leads to differences in their physical and chemical properties. As the results, these metallic nanoparticles have found a wide range of applications in almost all fields of research. Silver (Ag) nanoparticles are the most common one being employed in e...
ABSTRACT The study investigates the effect of propagation impairments such as rain, cloud, gases and tropospheric scintillation on fixed satellite communication link on earth-space path for frequencies between 10 and 50 GHz at Ku, Ka and V bands for 37 locations in Nigeria. Two standard elevation angles of 50, 550 as well as some elevation angles for links to recently launched Nigeria Communication Satellite, (NigComsat-1) were used in the computation of the propagation impairments for the...
Abstract There is no one treatment for cancer and the search for ways to combat cancer have led to many different treatments, including surgery, chemotherapy, and radiation therapy. However, these treatments are not always effective, and in such cases new treatments must be developed. Boron neutron capture therapy (BNCT) is a treatment that has been proposed to combat brain tumor and Neck tumors, two tumors that are resistant to traditional cancer therapies. Boron neutron capture therapy (BN...