A comparative study of the physical and mechanical properties of coarse aggregates produced in Ogun state

This study investigates the compliance of the physical and mechanical properties of granites produced in some parts of Ogun State to relevant codes and standards. The desire to carry out the study was borne by personal on – site experience that single size aggregates produced in some parts of Ogun State do not conform to grading requirements specified in relevant codes and standards. Samples of 9.5mm, 12.5mm, 19mm and 25mm aggregates were collected from four different quarry sites spread across the state. T he Samples were tested for their Specific Gravities, Water Absorptions, Moisture Contents, Aggregates Impact Value and Aggregates Crushing Value in accordance to the relevant standards. Test results reveals that all the samples conform to relevant codes an d standards . It was therefore concluded that although the aggregates do not conform to grading specification b ut the physical and mechanical properties of all the aggregates meet the specifications in relevant codes and standards. Key words: Evaluation, Physical, Mechanical, Properties, Aggregates and Standard

Heat And Mass Transfer Of Magnetohydrodynamic (Mhd) And Dissipative Fluid Flow Past A Moving Vertical Porous Plate With Variable Suction

An investigation was carried out on the radiation effect on unsteady heat and mass transfer of MHD and dissipative fluid flow past a moving vertical porous plate with variable suction in the presence of heat generation and chemical reaction. The dimensionless governing equations for this model were solved analytically using perturbation method. The effects of various parameters on the velocity, temperature and concentration fields as well as the Coefficient of skin-friction, Nusselt number and Sherwood number were presented graphically and in tabulated forms. Keywords: Chemical reaction, Unsteady, Porous medium, MHD, Radiation, Mass transfer and Heat sourc

Investigation of the physical and mechanical properties of Shea Tree timber (Vitellaria paradoxa) used for structural applications in Kwara State, Nigeria

This study investigated the physical and mechanical properties of Shea Tree timber (V. paradoxa) for structural use obtained at different areas of Kwara State, Nigeria. Physical properties of the samples like moisture content, specific gravity and density was evaluated and the mechanical tests were tensile strength, modulus of rupture, modulus of elasticity, compression, shear and hardness. Results show that, the density of the specie varied from 1.05 to 1.48 (g/cm3), and specific gravity varied from 0.98 to 1.39. For the mechanical properties, the results revealed that at 18% moisture content and 80% grade stress, mean MOR of 28.91(N/mm2), mean MOE of 9,108 (N/mm2), compressive strength parallel to grain of 24.7 (N/mm2), compressive strength perpendicular to grain of 8.99 (N/mm2), shear strength of 2.01 (N/mm2), and tensile strength parallel to grain of 16.15 (N/mm2). Finally, according to BS 5268-2 (2002) the specie was characterised into strength classes between D50 and D70. The results obtained showed that Shea Tree is a hardwood and suitable to be used for structural engineering purposes.Keywords: Vitellaria paradoxa, Physical properties, Mechanical properties, Structural timber, Green Constructio

Development of a horizontal three bladed windmill with vortex tubes

Researchers have been continuously searching for the most readily available means of producing electricity without any negative effect on the environment. Renewable source of energy like solar energy, hydro electric energy, biomass and wind energy has been considered as the alternative. Wind energy among others is rated the best renewable sources of energy because it’s level of environmental friendliness. In this paper, a horizontal windmill was designed, fabricated and its performance evaluated with two types of vortices and without a vortex. The component parts of the mills are towel, blades, shafts, base, tail vain and vortex. During the design of the windmill, consideration was given to the size, area of the blade and the blade material that produce maximum speed. The performance evaluation was carried out to compare the performance of the mill with the solid vortex, gap vortex and without vortex. The result of the evaluation reflects that the solid vortices have the highest wind speed irrespective of time of the day and with an optimum wind speed of 5.04 m/s. Also, the wind mill performed at a higher efficiency with the vortex compare to when it was running without vortex. &nbsp

Analysis of Independence of Available Infrastructure on Geographical Location of Public Secondary Schools in Ondo State, Nigeria

This paper has attempted to study the availability of infrastructural facilities in public secondary schools in Ondo State, Nigeria. Six local government areas (LGAs) were randomly selected with due consideration to the geo-political set-up of the State. Quantitative methods of analysis that were used include both descriptive and inferential statistics. The descriptive statistical techniques were tabular presentation and bar chart while the inferential statistical technique applied is chi-square analysis. The inferential statistics revealed that enrollment of students in secondary schools depends on gender and on Local Government Area. Also, the level of equipping of laboratories, availability of information technology facilities,  portable water supply and supply of electricity depend on Local Government Area while availability of library in secondary schools is independent of Local Government Area. Conclusively, much still need to be done in the area of infrastructural development in public primary and secondary schools in Ondo State towards the achievement of the vision 20: 2020 goal of Nigeria as one of the 20 most developed economy of the world in terms of education. Keywords:  education, infrastructure, information technology, chi-square, enrollment

A new method of vascular point detection using artificial neural network

Vascular intersection is an important feature in retina fundus image (RFI). It can be used to monitor the progress of diabetes hence accurately determining vascular point is of utmost important. In this work a new method of vascular point detection using artificial neural network model has been proposed. The method uses a 5×5 window in order to detect the combination of bifurcation and crossover points in a retina fundus image. Simulated images have been used to train the artificial neural network and on convergence the network is used to test (RFI) from DRIVE database. Performance analysis of the system shows that ANN based technique achieves 100% accuracy on simulated images and minimum of 92% accuracy on RFI obtained from DRIVE database

Predictive mathematical modeling and computer simulation of direct ethanol fuel cell

Abstract: The challenges of finding a better substitute of energy as well as the short comings identify with direct ethanol fuel cell, this includes; high anode over potential and crossover necessitate the need to investigate the influence operating parameters on the performance of fuel through computer simulation. This study focus on the development of a predictive mathematical modeling for direct ethanol fuel cell for the purpose of investigating the influence pressure, temperature cathode and reactants concentration on the performance, efficiency and heat generated by the cell. Results obtained indicate that increase in operating temperature resulted led to decrement in output voltage and cell efficiency, while same condition of increasing the temperature positively favour the heat generated from the cell. Simulated results also show that cell performance is improved with increase in concentration of the fuel (ethanol) and oxidant (oxygen). It can be inferred from this study that the cell performance of DEFC can be theoretically predicted with the developed model

Analysis of synchronous reluctance machine with magnetically coupled three-phase windings and reactive power compensation

Abstract: Synchronous reluctance machine with simple salient rotor is known to have poor power factor because of its poor reactance ratio. This study presents the use of an auxiliary winding attached to a balanced capacitor to improve the effective reactance ratio as well as the performance characteristics of synchronous reluctance machine. A unique feature of this configuration is that although the machine runs at synchronous speed, the effective reactance ratio of the machine can be improved by appropriate sizing of the capacitor attached to the auxiliary winding, with the constraint of the ampere turn rating of the auxiliary winding. The operational characteristics of a simple salient rotor synchronous reluctance machine equipped with this configuration were investigated and shown to have a desirable performance. How the effective reactance ratio, power factor and airgap flux distribution depend on the size of capacitor attached to the auxiliary winding is determined using a simplified mathematical model of the system. Analytical results and experimental measurements are in good agreement, and demonstrate the effectiveness and benefits of the configuratio

Vibration under variable magnitude moving distributed masses of non-uniform Bernoulli-Euler beam resting on Pasternak elastic foundation

The dynamic response to variable magnitude moving distributed masses of simply supported non-uniform Bernoulli-Euler beam resting on Pasternak elastic foundation is investigated in this paper. The problem is governed by fourth-order partial differential equation with variable and singular coefficients. The main objective of this work is to obtain closed form solution to this class of dynamical problem. In order to obtain the solution, a technique based on the method of Galerkin with the series representation of Heaviside function is first used to reduce the equation to second order ordinary differential equations with variable coefficients. Thereafter the transformed equations are simplified using (i) The Laplace transformation technique in conjunction with convolution theory to obtain the solution for moving force problem and (ii) finite element analysis in conjunction with Newmark method to solve the analytically unsolvable moving mass problem because of the harmonic nature of the moving load. The finite element method is first used to solve the moving force problem and the solution is compared with the analytical solution of the moving force problem in order to validate the accuracy of the finite element method in solving the analytically unsolvable moving mass problem. The numerical solution using the finite element method is shown to compare favorably with the analytical solution of the moving force problem. The displacement response for moving distributed force and moving distributed mass models for the dynamical problem are calculated for various time t and presented in plotted curves