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Search Results: 1 - 10 of 386825 matches for " Alabi J. O. "
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Modification of Darcy s Law for Turbulent Flow in Saturated Porous Media
O.I. Popoola,J.A. Adegoke,O. Alabi
Research Journal of Applied Sciences , 2012,
Abstract: Darcy`s law is an essential equation in determining the permeability of porous media, which is vital tool in seepage and drainage control in soils. However whenever the aggregate sizes of the porous media and hydraulic gradient are large, the flow in drains will be semi-turbulent to turbulent. This research aims at modifying the true Darcy s permeability determined under small hydraulic gradients that ensure laminar or nearly laminar flow to allow for reduced efficiency caused by turbulence at greater hydraulic gradient and provide a relation between the maximum gradient for laminar flow and porosity of the porous media. A modeled experiment was set up using sand samples of different porosities from riverbed as porous media, which were packed in a vertical transparent cylinder tube of diameter 1.85 10-2m and relative permeabilities were determined for gradient ranging from 1.15-15.00. The result of the experiment shows that relative permeability increases with increasing porosity but decreases with increasing gradient. The maximum (or limiting) hydraulic gradient for laminar flow decreases with increasing porosity. Also, the vertical fluid flow in any porous medium is laminar or nearly laminar as much as hydraulic gradient is less than or equal to 1.04.
The Effect of Foreign Direct Investment on the Nigerian Manufacturing Sector
Opaluwa David,Ameh. A. Abu,Alabi J. O.,Abdul Mohammed
International Business and Management , 2012, DOI: 10.3968/j.ibm.1923842820120402.1075
Abstract: This study examined the effect of Foreign Direct Investment (FDI) on the Nigerian manufacturing sector spanning 1975 – 2008. Nigeria has embarked on several policy measures aimed at enhancing the manufacturing sector’s productivity coupled with the inflow of FDI to the country. The controversy is that the policy makers are not convinced that the potential benefits of FDI could be fully realized. The methodology adopted for the study is the Vector Auto Regression (VAR), co-integration and error correction techniques to establish the relationship between FDI and the growth of manufacturing sector. The findings from the study show that FDI has a negative effect on the manufacturing productivity and is statistically significant. Arising from the findings, it is recommended that government should create an enabling environment for foreign investment and the monitoring of FDI benefits, with particular focus of NEPAD and NEEDS through the instrumentality of the MDGs; thereby mustering the capacity for sustainable growth in the manufacturing sector. Key words: FDI; Manufacturing sector; Productivity; Growth, Policy
A Laboratory Study of the Effects of Porosity on the Deviation from Darcy`s Law in Saturated Porous Media
O.I. Popoola,J.A. Adegoke,O.O Alabi
Research Journal of Applied Sciences , 2012,
Abstract: Darcy`s law for laminar flow of fluids in porous media is an essential assumption in determining permeability, magnitude and direction of seepage force and travel time of fluid in porous media. Sand samples of different porosities from riverbed were used as porous media, a modelled experiment was set up to determine the volume of water flowing across a unit cross sectional area per unit time in these saturated sand samples packed in a vertical transparent cylindrical tube of radius 1.85 10-2m. Values of volume flux rate were determined for hydraulic gradient between 1.875 and 30.000 by using vertical flow form of Darcy s equation. Darcy s law is not perfectly obeyed by all samples used because both volume flux and seepage velocity increase as smaller rate than hydraulic gradient. The extent of deviation from Darcy s law increases with decreasing porosity. The velocity is zero in sand samples A-E for gradient ranges of 0.029< i < 0.758. A plot of deviation from Darcy s law against porosity shows that deviation is related to porosity, with polynomial fitting of degree 2 with correlation coefficient of 0.99.
The Effects of Porosity and Angle of Inclination on the Deflection of Fluid Flow in Porous Media
O.I. Popoola,J.A. Adegoke,O.O. Alabi
Online Journal of Earth Sciences , 2012,
Abstract: 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 set-up consisting of a big transparent cylindrical pipe 108.5 cm long with radius 2.23 cm was used as inlet pipe and five small equal transparent cylindrical pipes with radii 0.3 cm were used as outlets, which were joined to the circular plastic plate on the top of the inlet pipe at different angles ranged from 0-90° 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 to higher angles from normal is when it flows through a medium of low porosity to that of higher porosity.
Forecasting in Subsets Autoregressive Models and Autoprojective Models
J.F. Ojo,T.O. Olatayo,O.O. Alabi
Asian Journal of Scientific Research , 2008,
Abstract: Full autoregressive models are always characterize by many parameters and this is a problem. Some of these parameters are redundant that is close to zero and there is the need to eliminate these parameters through the concept of subsetting. Subsets autoregressive models are free from redundant parameters thereby lowering the residual variance and forecasting with such models will always give a better forecast. Likewise auto projective models calculate on the basis of current knowledge what the errors would have been which gives us some guide to errors of the future. It is in the light of the above we considered the subsets autoregressive models and auto projective models, to see how these models will perform with regard to forecast. Exponential smoothening was used to forecast the future value in auto projective models while conditional least square predictor was used to forecast the future value in subset autoregressive models. An algorithm was proposed to eliminate redundant parameters from the full order autoregressive models and the parameters were estimated. To determine optimal models, residual variance, Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) were adopted. Results revealed that the residual variance attached to the subset autoregressive models is smaller than the residual variance attached to the auto projective models. We conclude that the forecast for subset autoregressive is preferred to the forecast for auto projective.
Assessments of Some Simultaneous Equation Estimation Techniques with Normally and Uniformly Distributed Exogenous Variables  [PDF]
O. O. Alabi, B. A. Oyejola
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.611167
Abstract: In each equation of simultaneous Equation model, the exogenous variables need to satisfy all the basic assumptions of linear regression model and be non-negative especially in econometric studies. This study examines the performances of the Ordinary Least Square (OLS), Two Stage Least Square (2SLS), Three Stage Least Square (3SLS) and Full Information Maximum Likelihood (FIML) Estimators of simultaneous equation model with both normally and uniformly distributed exogenous variables under different identification status of simultaneous equation model when there is no correlation of any form in the model. Four structural equation models were formed such that the first and third are exact identified while the second and fourth are over identified equations. Monte Carlo experiments conducted 5000 times at different levels of sample size (n = 10, 20, 30, 50, 100, 250 and 500) were used as criteria to compare the estimators. Result shows that OLS estimator is best in the exact identified equation except with normally distributed exogenous variables when \"\". At these instances, 2SLS estimator is best. In over identified equations, the 2SLS estimator is best except with normally distributed exogenous variables when the sample size is small and large, \"\" and \"\" ; and with uniformly distributed exogenous variables when n is very large, \"\" , the best estimator is either OLS or FIML or 3SLS.
Phosphorus Level Affects Brown Blotch Disease, Development and Yield of Cowpea
O.F. Owolade,M.O. Akande,B.S. Alabi,J.A. Adediran
World Journal of Agricultural Sciences , 2006,
Abstract: Application of Phosphorus in adequate concentrations could directly or indirectly reduce disease incidence and severity of cowpea brown blotch and improve the forage and grain yield. A field experiment was conducted to investigate the effects of level of phosphorus application on Brown Blotch disease of cowpea (Vigna unguiculata [L.] Walp), caused by Colletotrichum capsici during 2003, 2004 and 2005 planting seasons. Application of phosphorus was at 30, 60, 90 and 120 kg ha 1 of P2O5. As P level increased numbers of petioles, pods, nodules, seed/pod, leaf area and yield significantly increased. Disease incidence and severity of Brown Blotch were significantly reduced at 90 and 120 kg ha 1 of P2O5 was not affected irrespective of the method of application. Application method did not affect yield. Reduction in brown blotch disease at higher levels of P was recorded.
Assessment of the Impact of Women’s Organisations on Sustainable Rural Environment and Livelihood in Nigeria
K.O Ajadi, J.A Adebisi, F.M Alabi
Ethiopian Journal of Environmental Studies and Management , 2010,
Abstract: Worldwide, women organisations have contributed greatly to sustainable development, promoting development and encouraging progress, which help in reducing or eliminating poverty. The paper focuses on women in rural areas to examine the effort of women organisations (NGOs) in improving environmental education and economic empowerment of people in rural area sin Oyo State, Nigeria. Primary and secondary sources of data collection are used. This paper covers 50 rural settlements with 250 structured questionnaires distributed across same number of purposively-selected respondents in the study area. The result shows that 2% of respondents can read, write and understand Yoruba and English languages. They lack funds, special training to improve their practical indigenous expertise and talents in local economies. Nearly 47% have access to telephone but less than 25% have access to radio or television and none belongs to any registered governmental or non-governmental organisations. The study recommends the provision of viable infrastructure through government developmental assistance and funding from international partners to educate rural women on how to increase yield on their farms as well as undertake adult, community and environmental education, trainings in health and family planning. These are crucial to government’s drive to break the cycle of poverty and reverse environmental degradation.
Effect of ventilation opening levels on thermal comfort status of both animal and husbandman in a naturally ventilated rabbit occupied building
L.A.O. Ogunjimi,J.A. Osunade,F.S. Alabi
International Agrophysics , 2007,
Abstract: Three levels of ventilation openings (100, 30, and 50%) of inlet were considered in this study under a natural ventilation method for rabbit production. The study was conducted using a model animal building. The external and internal temperature and relative humidity were measured over the experimental period. The measure of thermal comfort within a locality was hence determined by temperature humidity index (THI) for both animal and husbandman while relative strain index (RSI) was also considered for man. The results showed that the amount of ventilation opening and building orientation have significant effects on the thermal comfort level of a building as indicated by the THI levels at 1% level of significance for both rabbit and man, which is also the same for the RSI for man. The larger the inlet opening and closer to perpendicular to the prevailing wind is the opening the higher is the thermal comfort level for both man and animal as seen in the values of THI for both rabbit and man and the RSI value for man in the case of 50% ventilation opening pens of the 90 ° orientation building. This may be attributed to the larger quantity of air passing through the building with increasing opening ratio. This affects the amount of heat and moisture that is removed from the building, hence the level of both temperature and relative humidity resulting in a more comfortable building internal environment for both animal and husbandman.
Empirical Determination of the Tolerable Sample Size for Ols Estimator in the Presence of Multicollinearity (ρ)  [PDF]
O. O. Alabi, T. O. Olatayo, F. R. Afolabi
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.513180
Abstract:

This paper investigates the tolerable sample size needed for Ordinary Least Square (OLS) Estimator to be used when there is presence of Multicollinearity among the exogenous variables of a linear regression model. A regression model with constant term (β0) and two independent variables (with β1 and β2 as their respective regression coefficients) that exhibit multicollinearity was considered. A Monte Carlo study of 1000 trials was conducted at eight levels of multicollinearity (0, 0.25, 0.5, 0.7, 0.75, 0.8, 0.9 and 0.99) and sample sizes (10, 20, 40, 80, 100, 150, 250 and 500). At each specification, the true regression coefficients were set at unity while 1.5, 2.0 and 2.5 were taken as the hypothesized value. The power value rate was obtained at every multicollinearity level for the aforementioned sample sizes. Therefore, whether the hypothesized values highly depart from the true values or not once the multicollinearity level is very high (i.e. 0.99), the sample size needed to work with in order to have an error free estimation or the inference result must be greater than five hundred.

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