Scholarly works

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An algoritm for solving electromagnetic field equations by finite element method
(Medwell Journals, 2007) Adetoyinbo, A. A.; Adewole, O. O.
Describing the behaviour of electromagnetic frequency responses from vertically inhomogenous and anisotropic earth of 2-Dimensional structures energized finite sources is computationally laborious. Differential equations were derived and their numerical solutions also sought for the desired components of electric and magnetic fields. Also, expressions for the impedance and apparent conductivity were stated. An algorithm based on the finite element method for computing approximate numerical solutions for these problems were dealinated.
Analysis of heavy metals concentration in sediments and water samples of selected functional dams in Oyo State, Southwestern Nigeria
(2008) Adegoke, J. A.; Sunmonu, L. A.; Ojeniyi, O. S.
"The quality as well as the quantity of clean water supply is of vital significance to the welfare of mankind particularly in the developing countries. Therefore, knowing the concentration of heavy metals present in Dams can help us to ascertain the health safety of the populace using the water for drinking and domestic purposes. Ten Dams at Oyo State in the Southwestern Nigeria were studied for the heavy metals concentration contained in the sediments and water of the selected Dams. Bottom sediments and water were collected from the selected dams for analysis. Analysis of both the water and sediments to determine the concentration of each heavy metal was evaluated. The result obtained shows that, the concentration of Manganese (Mn) ranges from 14.8 mg/kg to 332.96 mg/kg followed by Zinc (Zn) which ranges between 6.18 mg/kg and 52.53 mg/kg which spread across all locations., Lead (Pb) was not detected in virtually all the locations except in Ilora which has a concentration of 0.87 mg/kg and this may be as a result of the activities of motor mechanics and vulcanizers around the dam. In the water samples, the result showed that the concentration of heavy metals is very low which is far below the limit specified by World Health Organization (WHO). Zn has the highest concentration ranging from 0.049mg/kg to 0.729mg/kg, followed by Mn which has concentration between 0.011mg/kg and 0.344mg/kg. Pb, Cadmium (Cd) and Cobalt (Co) were not detected at all in all the water samples. The variation in the concentrations may be due to geological nature of the ground, solubility, an ion exchange and human activities. "
Assessment of building failure within and around quarries
(2019-07) Adetoyinbo, A. A.
The substructures of various engineering structures that were erected on the earth are being were been supported by the soil. Hence, the nature of the soil supporting these structures becomes an important issue. Quarry blasting peak particle velocity (QBPPV) is not sufficient to ascertain the causes of foundation failure, therefore, the physical parameters governing the competency of the soil supporting engineering structures need to be determine. This work investigated the possible causes of foundation failure of buildings within the vicinity of quarries. The investigation was done by carrying out Vertical Electrical Sounding (VES) and Radial Vertical Electrical Sounding (RVES) using Campus omega terrameter. The results show that buildings found within this area have shallow foundation and their foundations founded on sandy clay which can still support foundation The values of the degree of fracturing was found not to exceed 1.53 in this region which was not the case with the previous radial vertical electrical soundings, 1.94 was calculated as the highest degree of fracturing for RVES 1 while 1.83 was calculated for RVES 2. In all the RVES, degree of fracturing ranges between 1.02 to 1.94.
Assessment of ground water pollution in Itagunmodi, South-West, Nigeria
(2012-02) Adetoyinbo, A. A.; Bello, A. K; Hammed, O. S.
Some investigations have been earned out on geochemical characteristics of soil samples that embedded the ore deposits. Physiochemical analysis of water collected within gold mining area and the water consumed in the town of Itagunmodi was earned out to determine their hygienic conditions. The major objective of this study was to determine the suitability of the available water consumed in the town based on the Physiochemical analysis test carried out. In this regards, four major sources of water were analyzed. Analysis shows that the water within the town of Itagunmodi was hygienic with the inclusion of water within the mining site. The analysis includes; conductivity test, the pH test and others. It was noticed that the pH of the sample from the gold mining site was also suitable for drinking according to the World Health Organization standard. For a safe drinking water, the pH should be between (6.5 -8.5).
Assessment of groundwater quality in unconsolidated sedimentary coastal aquifer in Lagos State, Nigeria
(Academic Journals, 2009-04) Adebo, B. A; Adetoyinbo, A. A.
This study assesses the quality of ground water from nine different borehole locations in Lagos State, Nigeria. Borehole water samples were carefully collected for physico - chemical analyses. Calcium, magnesium, iron, zinc, copper, manganese, aluminium, and silver, Nitrate, phosphate, fluoride, chloride, pH, conductivity, total dissolved solid, total suspended solid, hardness, summation of ions as well as the temperature and colour were assessed among the entire samples collected. The results show that: temperature ranges from 26.6 - 27.8°C, pH (7.27), average conductivity (462.2 ps/cm), TDS (204.73 mg/l), Total hardness (18.48 - 297.70 mg/l) and Chloride concentration (343.3 mg/l). However, a high value of chloride, 343.3 mg/l, was recorded in one of the water sample collected but, this is higher and above the limit of WHO guidelines of portable water (250 mg/i). This may be due to the proximity of the area where the sample was collected to the sea. Five samples of the water are is soft, that is, hardness was within a range of 0 - 75 mg/l recommended for safe drinking water, one is moderately hard while three samples are hard. Also, the presence of metals such as zinc, manganese, sodium, copper and magnesium were also observed. Results show that not all the water samples are safe for drinking purposes.
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."
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 "
A computation of laminar flow in open channels and its application to sheet erosion
(Devon Science Company, 2011) Adegoke, J. A.; Egbeyale, G. B.
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."
Contemporary aspects of Monte Carlo methods and simulation in physics
(Faculty of Science, University of Abuja, 2004) Olowofela, J. A; Adegoke, J. A; Adewumi, O. P; Kamiyole, I. C.
"This article introduces Monte Carlo methods which are different from conventional numerical methods and show how some of the methods can be applied in Physics to stimulate or solve physical problems, through computer programmes (written in FORTRAN in this case) by using a few examples touching modern and classical physics showing its usefulness. A functional approach to probability and statistics is described for the purpose of this work instead of complete treatment. The importance of good sequence of random numbers with large periods is demonstrated and the methods, in same instance are compared with conventional type and differences pointed out. "
CONTRIBUTIONS OF NATURAL RADIONUCLIDES IN CHEMICAL FERTILIZERS TO FARM SOIL RADIOACTIVITY AND COMMITTED EFFECTIVE DOSES TO HUMAN
(2016-11) FASAE, K. P.
The use of chemical fertilizers to replenish depleted soil nutrients due to over cultivation and erosion is a common practice. Natural radionuclides in these fertilizers can cause some radiological adverse health effects to animal, through indirect ingestion of fertilizer, including consumption of plants grown with fertilizers. Information on the level of contribution of chemical fertilizers to farm soil radioactivity and radiological health effects in Nigeria are scanty. This study was designed to assess the contributions of chemical fertilizers to farm soil radioactivity and Committed Effective Doses (CEDs) to human. Samples of commonly used Nitrogen-Phosphorus-Potassium (NPK:15-15-15) and Single Superphosphate (SSP) fertilizers were collected from retail markets in southern and northern Nigeria, respectively. Three partitions (0.55m2 each) of rain-fed experimental farm was filled with Virgin Soil (VS), which was collected from government reserved forest in Ekiti State. The fertilizers (NPK and SSP) were applied separately to VS with NPK (VSNPK) and VS with SSP (VSSSP) using broadcasting method at 1.0 kg/m2. The third partition served as the control (VSC). Seeds of Tomato (Solanum esculentum K. Karsten) and vegetable (Amaranthus hybridus Linnaeus) were sown on the partitions after one week of fertilizers application. The contributions of chemical fertilizers to farm soil radioactivity and their transfer factors to plants were investigated using standard method. The activity concentrations of natural radionuclides in the fertilizers, soil and plant samples were measured using Sodium Iodide doped with Thallium (NaI(Tl)) detector. The CEDs were determined using standard equation as contained in Radioactivity in Food and the Environment (RIFE) documents. Data were analysed using descriptive statistics and one way ANOVA at . The Mean Activity Concentrations (MACs) of in NPK and SSP were 4754.0±192.0, 156.0±99.0 and 9.4±4.0 Bq/kg; 301.0±36.0, 696.0±113.0 and 14.7±2.7 Bq/kg, respectively. The MACs of in soil samples of the were 204.0±2.4, 43.0±2.3 and 7.0±1.7 Bq/kg; 352.0±1.9, 62.0±1.7 and 8.0±1.9 Bq/kg; 285.0±3.3, 66.0±2.0 and 10.0±1.4 Bq/kg, respectively. The MACs of the three radionuclides in tomato samples of the VSC, VSNPK and VSSSP were 64.0±1.4, 18.0±1.7 and 7.0±1.7 Bq/kg; 125.0±2.1, 33.0±2.0 and 8.0±1.9 Bq/kg; 122.0±1.7, 51.0±1.4 and 10.0±1.4 Bq/kg, respectively were 72.0±1.4, 22.0±1.7 and 8.0±2.6 Bq/kg; 133.0±1.7, 45.0±1.9 and 10.0±1.9 Bq/kg; 142.0±2.3, 57.0±1.7 and 13.0±2.1 Bq/kg for respectively. Differences in MACs were significant in samples considered. Use of NPK and SSP contributed and respectively to the activity concentrations of in the VSNPK and VSSSP compared to the VSC farm soil. Radionuclide transfer factors in the VSC, VSNPK and VSSSP ranged from 0.36-0.66, 0.35-0.56 and 0.43-0.78, respectively. The CEDs due to consumption of tomatoes and vegetable of VSNPK and VSSSP were 0.22 and 0.11 and respectively, which are lower than the recommended CED of by International Commission on Radiological Protection (ICRP). The NPK and SSP fertilizers in the VSNPK and VSSSP contributed 54.0 and 130.0 %, respectively to the CED (tomatoes), 37.0 and 73.0 %, respectively to CED (vegetables) when compared to plants in the VSC. Chemical fertilizers contribute to farm soil radioactivity and the committed effective doses to human is elevated more by Single Superphosphate fertilizer
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. "
Depending of thermophysical properties of clay on concerntation of some heavy metals
(Duncan Science Compnay, 2011) Adegoke, J. A.; Egbeyale, G. B
"This paper presents the relationship between thermo physical properties (thermal conductivity and thermal diffusivity) and heavy metal concentration of some surface clay from six local governments in Ibadan, Oyo state, Nigeria. An atomic absorption spectrometer (AAS) was used in analyzing the concentration of heavy metals present in each sample by measuring the intensity of external radiation absorbed by the atom produced from the same sample at a wavelength characteristic to that element. A transient measurement technique was wed to determine the thermal conductivity and thermal diffusivity. Thermal conductivity of each sample was compared with the concentration of heavy metals present in the sample. Based on the results obtained from AAS, Manganese has the highest concentration in all the samples. It was followed by Zinc and the least was lead. The values of temperature, time and their respective measured thermal conductivity were highly correlated; with correlation coefficients between 0.9 and 1. "
Depth probing soft x-ray microprobe (dpsxrm) for high resolution probing of earth’s microstructural samples
(2016-06) Dikedi, P. N.; Adetoyinbo, A. A.
The Cambrian explosion: occurrence of landslides in very dry weather conditions: rockslides; dead, shriveled- up and crumbled leaves possessing fossil records with the semblance of well preserved, flat leaves: abundance of trilobite tracks in lower and higher rock layers: and sailing stones are enigmas demanding demystifications. These enigmas could be elucidated when data on soil structure, texture and strength are provided by some device with submicrometre accuracy; for these and other reasons, the design of a Depth Probing Soft X-ray Microprobe (DPSXRM), constituting a rotating X-ray window is being proposed; it is expected to deliver soft X- rays, at spatial resolution, Ω 600nm and to probe at the depth of 0.5m in 17s. Assessing subsurface stratigraphy is possible with the DPSXRM. The microprobe is portable comparedfo a synchrotron radiation facility (Diamond Light Source has land size of 43,300m* 2); spatial resolution,'q > 600nm, of the DPSXRM surpasses those of the X-ray Fluorescence microanalysis(lOpm), electron microprobe (I-3pm), and ion microprobe (5->30pm); the DPSXRM has allowance for multiple targets. Amongst other major optical components, a Fresnel Zone Plate (FZP) and Rotating X-ray Window are incorporated into the design to ensure that the desired image resolution is achievable and that the X-ray window membrane material survives the heat flux importation on it. Reflecting, refracting, diffracting and (or) absorbing optics areddentified as techniques needed to achieve this resolution. Vanadium and Manganese membranes are proposed owing to respective 4.952KeV VKa, and\ 5.899KeV MnKai X-rays emitted, which best suits micro-probing of Earth's microstructural samples. Compound systems like the Kirk-Patrick and Baez, electromagnetic lenses, small apertures and Abbe sine condition are considered to reduce or remove astigmatism and coma and spherical aberrations—leading to good image quality. Results are presented alongside, and relevant graphs are plotted. Magnification values of - 1.5 ≤ M ≤ 1.5, at - 70° ≤ θ ≤ 75° when - 30° ≤ θ ≤ 30° satisfied Abbe Sine Condition. The nth zone radius increases with the distance of separation of the DPSXRM’s electron gun and the zone plate. 5.899KeV MnKat and 4.952KeV VKa soft X-rays will travel a distance of 2. 75mm to form circular patches of radii 2.2mm and 2.95mm respectively. Zone plate with nth zone radius of 1.5mm must be positioned 1.5mm and 2 mm from the electron gun if circular patches must be formed from 4.952KeV VKat and 5.899KeV MnKajSoft X-rays respectively. The focal lengths of 0.25µm < F < 1.50µm and 0.04µm < F < 0.2µm covered by 4.952KeV VKat and\ 5.899KeV Mn Kat soft X-Rays, will occupy circular patch of area 0.03 mm2 < A < 0.2 mm2 respectively. The spatial resolution of 244nm < ς < 1460nm is attainable forfocal lengths of 38.1nm < F < 229nm and 32.0 nm < F < 1460192nm covered by 5.899KeV Mn Ka, and 4.952KeV VKa soft X-rays, respectively. Simulation results from COMSOL Multiphysics software uncover some deformations in Vanadium and Manganese microstructures.
Detection of decay and hollows in living almond trees (terminalia catappa L. roxb.) using electrical resistivity method
(Springer, 2018-10) Soge, A.; Popoola, O.; Adetoyinbo, A.
A precise and cost-efficient diagnostic technique for detecting decay and other structural defects in living trees is indispensable for the risk assessment and conservation of urban and forest trees. A study was carried out to detect the location and extent of decay and hollows (or cavities) in almond trees (Terminalia catappa L. Roxb.) using the four-point electrical resistivity method. Electrical resistivity measurements (ERm) of randomly selected living almond trees were taken using an earth resistivity meter, four probes and a modified form of Schlumberger electrode configuration. The ERm were used to obtain resistivity profiles (RP) of the trees. The RP of freshly cut healthy, decayed and hollowed trees were also obtained. A laboratory experiment was set up to replicate the RP of healthy, decayed and hollowed trees. Wood decay and cavities in trees were detected through RP matching. In comparison to healthy trees, wood decay and cavities in tree stems were detected with relatively sharp decrease and increase in electrical resistivity values, respectively. The extent of the resistivity anomalies corresponds to the extent of wood decay and cavities in trees. This method is applicable to early detection of decay and cavities in hardwood trees.
Detection of seismic ULF geo-electrical potential variations as tremor precursors prior to quarry blasts
(2009-05) Adetoyinbo, A. A.; Popoola, O. l.; Hammed, O. S.; Sumonu, L. A.
A seismic ultra low frequency geo-electrical signal recording instrument was set up in three different quarry sites in the south-western part of Nigeria. This research was embarked upon to detect geo- seismic electrical signals produced from the brittle upper crust during rock loading and fracture as a simulated earthquake precursor. The seismic electromagnetic signals emitting from the interior earth in analogical pattern and detected at the earth surface through the signal detectors were transmitted to a conditioning circuit which not only protected the recording instruments from transients caused by ionospheric disturbances but also attenuated the 50 or 60 Hertz frequency caused by high voltage power transmission lines. The spectral analysis of the ULF signals with sampling of 48 KHz recorded during rock loading and fracture in each of the stations revealed that the amplitudes of the signals decrease with increasing frequency. The geo-electrical potential signals associated with ULF waves were varying during deformation stages of crustal layers of rocks. These signals were recorded a few seconds before and after fracture of the rocks as systematic precursors to the main tremors observed in each of the stations and felt five (5) kilometers away.
Determination of stress-bulk modulus in the lithosphere and the peak particle velocity with regards to sediment-hosted disseminated gold deposit
(2017-03) Adetoyinbo, A. A.; Bello, A. K.
The tectonic activities happening within the subsurface has led to a huge trapped pressure within the plate boundaries looking for escape through the weakest points to the surface. This has led to deformation in the lithosphere which was greatest at the plate boundaries. In recent time, sediment-hosted disseminated gold deposits had been an important ore mineralization. From research it was suggested that gold, a material from subsurface derived from the core-mantle region passes through different regions of different densities, pressures and temperatures. Bulk modulus, an important parameter determined from the thermodynamic properties was investigated to the depth of the lithosphere. The ground movement was also determined with a view to ascertain the save distance and precautions when handling explosives as tools in underground mining.
Determination of temperature profile of the lithosphere between zero and 150 km penetration at Itagunmodi, Nigeria
(AJOL, 2019-06) Adetoyinbo, A. A.; Bello, A. K.
In this work the temperature profile for the lithosphere was determined using data from radiogenic heat source and heat from other sources from 0 to 150 km depth was determined using a suitable mathematical expression. The temperature at the base of the lithosphere was given between 1200°C to 1600°C. The Fourier’s law was applied and the results showed that the profile range from 27.0°C to 1483.3°C. These results compared favourably well with existing literature values.
Determination of transition length in flow through porous sand material
(2009) Adegoke, J. A.; Olowofela, J. A.
A transition length is normally observed when fluid flows through a conduit before laminar flow is accomplished. This work examined a situation whereby porous materials were filled into the conduit and fluid was made to flow through. An attempt was made to determine this transition length for flow of water through riverbed sand of varying porosities filled into a horizontal cylindrical pipe of diameter 0.345 x 102m with piezometric water head, set at 0.06m. The transition length was observed to be constant for the samples considered and it occurred at 0.60m from the point of entrance; nevertheless, values of pressure at this point increases with increase in porosity.
Effect of porosity on surface of drawndown in an unsteady state drainage in porous material. I
(2007) Olowofela, J. A .; Adegoke, J. A; Bejide, F. A.; Okeyode, I. C.
"This work considered the unsteady state drainage of fluid from a vertical column of porous material of varying porosities in an attempt to verify variation of drawndawn surface with porosity and time using riverbed sand. Kerosene was used as the flowing fluid. Mathematical assumptions ware made in connection with Darcy's law. The result showed that the experiment which was designed from the theoretical framework agreed with the theory to a large extent, However, this is not in perfect agreement with an earlier experiment which was performed using well rounded beads in which glycerine was used as the flowing fluid. A FORTRAN program was written to study the variation theoretically and this was compared with the experimental result. There exists, a degree of discrepancy between theory and experiment indicating that, the mathematical formulations did not perfectly agree with the complex earth system as compared with the bead model that was initially used. There is a need for the modification of the mathematical formulations; nonetheless, an unsteady drawndown, pattern was attained with different porosity even in medium with very complex geometry. "