FACULTY OF SCIENCE
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Item 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.Item 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.Item 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.Item On the stability and ultimate boundedness of solutions for certain third order differential equations(Science Publications, 2008) Ademola, T. A.; Arawomo, P. O.With respect to our observation in the relevant literature, work on stability and boundedness of solution for certain third order nonlinear differential equations where the nonlinear and the forcing terms depend on certain variables are scare. The objective of this study was to get criteria for stability and boundedness of solutions for these classes of differential equations. Approach: Using Lyapunov second or direct method, a complete Lyapunov function was constructed and used to obtain our results. Results: Conditions were obtained for: (i) Uniform asymptotic stability and, (ii) Uniform ultimate boundedness, of solutions for certain third order non-linear non-autonomous differential equations. Conclusion: Our results do not only bridge the gap but extend some well-known results in the literature.Item Boundedness and stability of solutions of some nonlinear differential equations of the third-order(2009) Ademola, T. A.; Arawomo, P. O.Sufficient conditions are established for the uniform ultimate boundedness of solutions of a third-order nonlinear differential equation (1). When, p(t,x,x',x")=0, criteria under which all solutions x(t), its first and second derivatives tend to zero as t→∞, are given.Item Stability results for the solutions of a certain third order nonlinear differential equation(Global Publishing Company, 2008) Ademola, T. A.; Ogundiran, M. O.; Arawomo, P. O.; Adesina, O. A.The paper is concerned with the uniform asymptotic stability for all solutions of a third order nonlinear differential equation (1.1). Sufficient conditions under which all solutions x(t), its first and second derivatives tend to zero as t —∞ are givenItem An interval analytic method in constructive existence theorems for initial value problems(Dynamic Publishers, 2002) Arawomo, P. O.; Akinyele, O.The method of interval analysis is employed to show that the solution, if it exists, of a first order initial value problem is majorised by an interval function whose end- functions satisfy some prescribed conditions. An interval operator is constructed and shown to be a contraction on the majorising interval function. Using this operator, the existence and uniqueness of the solution is established.Item Existence results for some interval differential equations(American Mathematical Society, 2000) Arawomo, P. O.This paper is concerned with the problem of existence of solutions to interval differential equations which result from attempts to provide a concide interval solution to some differential equations with inexact data or parameters contained in an interval. An extension of the interval iterative scheme of Moore is used to establish the main results which include those of Sveloslav Merkov’s.Item Interval valued extension of wendroff type integral inequalities(Elsevier, 2009) Arawomo, P. O.In this paper we extend the theory of integral inequalities to interval valued mappings in two independent variables. By this, set inclusions are used instead of partial order relation and this enables us to obtain simultaneous upper and lower bounds instead of a pair of inequalities.Item On the precise order of unit groups of burnside rings of some finite abelian group(2008-05) EniOluwafe, M.We determine the precise order of B * (G), for G = ©i Gi, a bounded abelian 2-group, where G, is a direct sum of r copies of a cyclic group of order 2". The cases r = 1 and r = k, for some natural number k, are respectively considered in this paper.