Scholarly works
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Item The effects of porosity and angels of inclination on the deflection of fluid flow in porous media(Medwell Journals, 2009) Popoola, O. I.; Adegoke, J. A.; Alabi, O. O."The movement of contaminated fluid from a solid waste landfill into a portable water aquifer located beneath is an example of unwanted underground flow. With the problem of limited portion of land available for building construction in the cities, coupled with the rise in price of good and accessible land, there is a need for quick and urgent solutions to environmental pollution that may be resulted from this problem. In this research, a laboratory setup consisting of a big transparent cylindrical pipe 108.5cm long with radius 2.23cm was used as inlet pipe and five small equal transparent cylindrical pipes with radii 0.03cm were used as outlets, which were joined to the circular plastic plate on the top of the inlet pipe at different angles ranged from 00 to 900 from a normal point. The inlet pipe and outlets pipes were filled with samples of soil of different porosities and titled at different angles of inclination. The volume of water discharged was measured directly with measuring cylinder from the set-up in each case. The volumetric flow rate and volume flux were computed from the values of volume discharged. These were done in order to determine how the arrangement of porous material of different porosities with a particular angle of inclination can influence the deflection of fluid flow from its linear direction. This is sequel to its practical applications in designing a construction with a cross-section of soils in deflecting contaminated fluid from septic tank to different directions from the source of water within the same small portion of land. It was observed that angle of inclination does not have a significant effect on the deflection of fluid but volume flux increases with increasing angle of inclination. Also, the greater the difference in the porosity of the cross-section of the media in which the fluid is flowing the greater the volume flux. However, the most suitable arrangement of cross-section of soils for deflection of fluid at higher angle from normal is when it flows through a medium of low porosity to that of higher porosity. "Item Stratified saturated control of bacteria migration in porous media: an experimental investigation(2013) Adegoke, J. A.; Ogunjobi, A. A.; Lateef, T. A."The importance of sand bed filters has gained more ground in on- site water treatment facilities. The performance of which depends on the design of the sand bed. A laboratory column experiment was designed to quantitatively determine the best kind of sand layered arrangement for maximal bacteria attenuation. Porosity was taken as media parameter to further examine the relationship between the layers that will yield a better performance. Porosity was determined using volumetric approach and vertical downward flow for the column filtration. Escherichia coli and Staphylococcus aureus was used as contaminants. The results revealed that the larger the difference in porosity of the layers the better the filter performance and that least porous material should be below followed by the larger one arranged in the direction of flow. It was also shown that for homogeneous layered media, the more the number of layers, the better is the filter performance. These inferences would help in better design of stratified sand filter systems both for water purification and fishpond effluents treatment systems."Item Characterizing buried metallic objects in porous media from attenuation fluctuations(Academic Journals Inc, 2013) Akinyemi, O. D.; Adegoke, J. A.; Salam, M. A.; Badmus, B. S.; Awokola, S. O."Study of attenuation characteristics of electromagnetic signals passing through porous media is becoming increasing relevant in providing important insights into the physical properties of the medium and objects that are buried therein. Laboratory experiments have been carried out in this work to determine the relationship between Q-factor of the electromagnetic signal passing through buried metals and the porosity of the surrounding sediments. Sediments were obtained from Erinle River in Ilobu, Southwestern Nigeria and Iron, Silver and Copper plates of similar dimensions were buried inside box-filled sediment in succession. Electromagnetic signal was passed through metal, sediments and sediments with buried metals while lissajous figures generated at different frequencies were analyzed to assess the impacts of buried objects. Results showed that Q-factor decreased as the porosity of riverbed sediments increased. Of the metals buried inside the sediments, Iron had the most attenuation effect while Silver plates had the least, except at frequency 400Hz where Copper had the least and at 600Hz where there were some overlaps between Silver and Copper. Q-factor increased, for all metals and at all signals frequencies, up to a maximum value at the porosity of 0.24 and thereafter decreased. Knowledge of Q- factor from attenuated signals is therefore, a useful way to characterize and identify buried materials "Item Variation of attenuation of bacteria migration with volume flux rate and porosity in porous media(Global Journals Inc(USA), 2012) Adegoke, J. A.; Ogunjobi, A. A.; Lateef, T. A."Efficiency of water treatment system grossly depends on the attenuation capacity of the filter media. Under natural condition, this capacity depends on the effects of physical, chemical and biological factors of which past works revealed few observation on physical factors under an explicit and simple experimental designs. In this work, we examined the variation of volume flux rate and porosity on the attenuation of migration of bacteria in sand media as can be applicable to water treatment system. Movement of Escherichia coli through matrix of different porosities in trends was studied in down – flow column experiment under natural and intermittent transport. Porosity values range between 0.28 and 0.42 while volume flux rate range between 0.82 x 10-4 m/s and 195.93 m/s respectively. The plot of normalized concentration versus volume flux was best fitted with polynomial curve of second degree which shows that attenuation of migration was partially varies with volume flux and not linear as revealed in past works. However attenuation of bacteria migration depends on the porosity as a function of depth ‘ɸ(x)’. "Item A case study of the depth of fresh/ Salt water interface using values of freshwater heads in groundwater of variable density(2012) Adegoke, J. A.; Owoeye, O. I.; Ozebo, V. C."Almost two thirds of the world's population lives within 400 km of the ocean shoreline; just over half live within 200 km, an area only taking up 10% of the earth's surface. As the world's population continues to grow at an alarming rate, fresh water supplies are constantly being depleted, bringing with it issues such as saltwater intrusion and increasing the importance of groundwater monitoring, management, and conservation. Constant monitoring of the fresh/salt water interface is necessary for proper management of ground water resources. This work studies the variation in the depth of fresh/salt water interface using different values of freshwater heads extracted from heads in coastal groundwater system near The Hague, Netherlands along sections P-DD. Results showed that high density difference between freshwater and saltwater has little effect on the depth of fresh/saltwater interface."Item Groundwater contaminated by nitrates- a case study of Ado-Ekiti, Ekiti state, southwestern Nigeria(David Publishing, 2012) Lateef, T. A.; Adegoke, J. A."Nitrate is one of the problematic and wide spread contaminations. Indiscriminate disposition of human and animal wastes in Nigeria especially in urban region, and lack of proper environmental sanitation geared the need for the monitoring of groundwater contamination. This research work monitored the concentration of nitrate and nitrate-nitrogen in portable water from wells in Odo Ado, Ado-Ekiti, Ekiti State, and examined the relationship between this concentration and the well depth as well as its nature (ringing). The results showed that out of 20 water wells sampled, 50% of samples contain high level of nitrate with the highest having concentration of 140 mg/L and least 49 mg/L while the remaining has acceptable concentration ranging between 3.5 mg/L and 35 mg/L with most ringed wells. The mean concentration of nitrates is 48.06 mg/L and the nitrate-nitrogen is 10.85 mg/L. The statistical correlation between the concentrations and depth showed that there is a significant difference between their means at 95% confidence using T-test. Out of ringed wells, five have high concentration and eight have low concentrations while two of the wells (not ringed) fall below the acceptable limit (EPA) which indicates that there are other factors such as closeness to the point source and soil texture which were not considered in this work. Key words: Nitrate, contamination, depth, groundwater, aquifer."Item The concerntration of heavy metals in selected clay samples in ekiti state, southwestern Nigeria(2011) Adegoke, J. A.; Oseni, S. O.; Adegbola, R. B."The presence and possible effect of heavy metal (such as cadmium, zinc, lead, e.t.c) concentration in the clay used in pot making were investigated. Clay samples were collected at three locations where they are used mostly in making pots and other kitchen utensils. The concentrations of heavy metals were determined using the Atomic Absorption Spectrometer (AAS). Results indicate that the concentration Cu, Zn, Cr, Pb, As, and Mn falls within the range of the maximum admissible concentration of heavy metals of several countries mostly in Europe. However, the concentration Cadmium and Nickel are relatively higher than the maximum admissible concentration of toxic metals in soil for countries like Denmark and Sweden."Item Lead adsorption in clay and its application(EJGE, 2012) Adegoke, J. A.; Babatunde, E. G."This work presents the adsorption capacities of some heavy metals in clay soil and its application in medical field. Nitrate of lead solution of different concentrations were prepared (400ppm, 800ppm… 6400ppm). Each concentration of lead nitrate solutions was mixed with a known volume of clay. Slabs of regular dimensions were formed from the residue after it had gone through filtration. Each slab (dried) was irradiated with x-ray radiation at different energies; 40kev, 60kev, 80kev,100kev and 120kev. Linear and mass attenuation of each slab were determined. We did this in order to check shielding ability of the adsorption capacities of heavy metals in clay soil. The research works on clay soil used mainly in building construction and pot making. A PTM UNIDOS electrometer at National Institute of Radiation Protection Research (NIRPR), University of Ibadan, was used to record the counting .A Graph of logarithm of incident intensity versus logarithm of transmitted intensity was plotted to calculate mass attenuation of the slabs at different concentrations. An Atomic Absorption Spectrometer (AAS) was used in analyzing the concentration of heavy metals present in each sample. The results obtained from X-ray Photoelectron Spectroscopy (XPS) show that attenuation coefficient decreases as the radiation energy increases. The linear correlation coefficient between the concentration of heavy metals and attenuation coefficient was approximately 1. "Item The impact of the variability of ionospheric phase refractive index on radio signals instability(Academic Journals, 2011) Awe, O. E.; Adegoke, J. A.; Eniafe, B. S.The ionospheric phase refractive index is a complex function that determines the attenuation and the trajectory of radio signals through the ionosphere. This complex refractive index model has been obtained using the Maxwell's equations, the tensorial conductivity equation, electron collision models, and the geomagnetic field model. The model has been used to study and investigate the phase refractive index on radio wave propagation for high latitude, low latitude and equatorial regions of the global ionosphere, at 1400 h LT, during the periods of high solar activity (Rz = 104.5, year 1970), moderate solar activity (Rz = 68.9, year 1972) and low solar activity (Rz = 12.6, year 1976). Our results showed that ionospheric phase refractive index is not constant, less than unity, increases with increasing propagating radio frequencies and for a particular propagating radio frequency, it increases with decreasing solar activityItem Dependence of attenuation of ionizing radiaion on compression and dimension of geologic material (an application to X-ray shielding)(2011) Adegoke, J. A.; Olowomofe, O. G."Search for alternative materials required for shielding ionizing radiation has being on the increase for some period of time. Lead which is widely used is expensive, therefore researches has to be carried out on other materials. Clay has been suggested but it is not as effective as lead in shielding ionizing radiation. This work therefore studies the compression of clay samples at different pressures and thicknesses, so as to improve its shielding ability in the attenuation of ionizing radiations. The research work was on pure clay material and studied their effectiveness as radiation shielding material. The samples were made in bricks and their linear attenuation coefficients were measured at two different X-ray energies of 60keV, 10 mA and 120 keV, 15 mA. The samples were compressed at a pressure of 875Nm-2, 1750 Nm-2, 2625 Nm-2, 3500 Nm-2, and 4375 Nm-2, for thicknesses of 1.0cm, 1.5cm, 2.0cm, 2.5cm,and 3.0cm. The result obtained shows that as the thicknesses increases, the linear attenuation increases which is in conformity with Lambert beer’s equation. The attenuation coefficient obtained shows increase in value when compared to ordinary clay samples that were irradiated without compression. "