Journal Articles

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Journal Articles (Mechanical Engineering)

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Open Access
Assessment of Wind Power Potential and Wind Electricity Generation Using WECS of Two Sites in South West, Nigeria
(International Journal of Energy Science(IJES)., 2011-02) AJAYI, O.O.; FAGBENLE, R.O.; KATENDE, J
The study was used to analyze the wind characteristics of Shaki (08.40’ N; 03.23’ E; Altitude 457.0 m; Air density 1.1723 kg/m3) and Iseyin (07.58’ N; 03.36’ E; Altitude 330.0 m; Air density 1.1869 kg/m3), two local sites in Oyo State, Nigeria. 21 years monthly mean wind speeds at 10 m height obtained from the Nigeria meteorological department were employed together with the Weibull 2-parameter distribution and other statistics to carry out monthly, seasonal and whole years’ analyses of the sites’ wind profiles for electricity generation. It was found that the whole data spread ranged between 0.9 and 9.1 m/s for the two sites while the 21 years’ average ranged between 3.2 and 5.1 m/s and 2.9 and 4.7 m/s for Shaki and Iseyin sites respectively. Three wind energy conversion systems were employed with the results and it was discovered that, the sites have capacity to generate MWh to GWh of electricity at an average cost/kWh of between € (0.025 and 0.049) and that a turbine with technical parameters of cut-in, cut-out and rated wind speeds of 3.0, 25 and 11.6 m/s is appropriate for the sites.
Open Access
DEFORMATION AND DEHULLING OF SPONGE GOURD (LUFFA AEGYPTIACA) SEEDS
(Taylor & Francis Group., 2011-03-03) Koya, O.A; Ogunsina, B.S; Opeyemi, O.O
This work presents the compressive strength properties of sponge gourd (Luffa aegyptica) seeds to facilitate the design or adaptation of an appropriate dehuller. The sizes and shape indices of the seed and kernel, and the clearance of the kernel from the seed coat were determined. The seed samples were subjected to uni-axial quasi-static compression tests at 1.0 mm min−1 along the minor and the major axes. The fracture resistance, stiffness modulus, modulus of elasticity, toughness, and maximum elastic deformation of the seed were obtained from the force-deformation curve. The geometric mean diameters varied from 4.0 to 4.5 mm for the seed and 1.6 to 3.9 mm for the embedded kernel; while their corresponding sphericities were 0.64 and 0.62, respectively. The compressive strength of the seed varied with loading orientation. The seed exhibited larger deformation but lower stiffness along the major axis than the minor axis. The force required for rupturing the hull were 95 N along the major axis and 81 N along the minor axis; while the corresponding energy required were 95 and 40 mJ.
Open Access
Deformation and fracture of dika nut (Irvingia gabonensis) under uni-axial compressive loading
(Institute of Agrophysics, Polish Academy of Sciences, 2008-01-16) Ogunsina, B.S; Koya, O.A; Adeosun, O.O
Fracture behaviour of dika nut under quasi-static loading along the longitudinal axis and the transverse axis was investigated. The fracture resistance of the nut was measured in terms of average force, deformation and toughness at nutshell fracture, and nut stiffness. Physical dimensions and shape of the nut, to provide for complementary input in design of handling equipment, were also determined. The force required to crack the nut increased with nut diameter but was not significantly different in both loading orientations. The mean cracking force was in the range of 2.06 to 3.67 kN. The compression of the nut exhibited a pronounced linearity between load and deflection. Dika nuts loaded along the transverse axis required less energy for nutshell fracture than those loaded along the longitudinal axis. Minimum toughness occurred with the small size nuts loaded along the transverse axis, thus providing base-line data in future design of an appropriate nutcracker.
Open Access
Development of an okra slicing device.
(Journal of Food Science and Technology -Mysore-, 2007-07) Owolarafe, O.K; Murital, O.A; Ogunsina, B.S
A manually operated lady’s finger (okra) (Abelmoschus esculentus) slicing device suitable for on-farm use was designed, fabricated and tested based on the engineering properties of the vegetable. The machine, simulates the traditional method of okra slicing, consists of the feeder, slicer and receiver. It was made simple for ease of operation and maintenance. The machine was tested with replicated experimental runs using 100, 200, 300, 400 and 500 g of okra. The thickness of the slices (about 10 mm) corresponds evenly to the spacing of the cutting discs. The machine has a slicing efficiency of about 77.4% and throughput of about 8.4 kg/h
Open Access
Effects of interatomic potentials on the determination of the minimum depth of cut in nanomachining
(Inderscience Enterprises Ltd., 2013-01) Oluwajobi, A.O.; Chen, X.
The minimum depth of cut (MDC) is a major limiting factor on achievable accuracy in nanomachining, because the generated surface roughness is primarily attributed to the ploughing process when the uncut chip thickness is less than the MDC. This paper presents the material removal in a nanomachining process, where a sharp diamond tool with an edge radius of few atoms acts on a crystalline copper workpiece. The molecular dynamics (MD) simulation results show the phenomena of rubbing, ploughing and cutting. The formation of chip occurred from the depth of cut thickness of 1~1.5 nm. Also, the effects of the interatomic potentials on the MDC have been presented
Open Access
Effects of interatomic potentials on the determination of the minimum depth of cut in nanomachining.
(International Journal of Abrasive Technology, 2013-01) OLUWAJOBI, A.O.; CHEN, X.
The minimum depth of cut (MDC) is a major limiting factor on achievable accuracy in nanomachining, because the generated surface roughness is primarily attributed to the ploughing process when the uncut chip thickness is less than the MDC. This paper presents the material removal in a nanomachining process, where a sharp diamond tool with an edge radius of few atoms acts on a crystalline copper workpiece. The molecular dynamics (MD) simulation results show the phenomena of rubbing, ploughing and cutting. The formation of chip occurred from the depth of cut thickness of 1~1.5 nm. Also, the effects of the interatomic potentials on the MDC have been presented
Open Access
An Improved Pole-and-Knife Method of Harvesting Oil Palms
(CIGR Ejournal, 2007-06) ADETAN, D.A.; ADEKOYA, L.O.; OLADEJO, K.A.
A modified pole-and-and-knife (MPK) method of harvesting oil palms was designed and fabricated. The method was tested along with two existing methods, namely the bamboo pole-and-knife (BPK) and the single rope-and-cutlass (SRC) methods. Test results showed that the MPK method was superior to the other methods in reducing the time spent in searching for and collecting scattered loose fruits (and hence the harvesting time), increasing the recovery of scattered loose fruits, eliminating the waist problem of the fruit collectors and increasing the ease of transportation and use of the harvesting pole
Restricted
An Improved Pole-and-Knife Method of Harvesting Oil Palms
(CIGR Ejournal, 2007-06) ADETAN, D.A.; ADEKOYA, L.O.; OLADEJO, K. A.
A modified pole-and-and-knife (MPK) method of harvesting oil palms was designed and fabricated. The method was tested along with two existing methods, namely the bamboo pole-and-knife (BPK) and the single rope-and-cutlass (SRC) methods. Test results showed that the MPK method was superior to the other methods in reducing the time spent in searching for and collecting scattered loose fruits (and hence the harvesting time), increasing the recovery of scattered loose fruits, eliminating the waist problem of the fruit collectors and increasing the ease of transportation and use of the harvesting pole
Open Access
An integrated impact assessment of hydrogen as a future energy carrier in Nigeria's transportation, energy and power sectors
(Elsevier Ltd., 2014) Amoo, Leye.M; Fagbenle, R.Layi
A hydrogen economy, the long-term goal of visionary nations, has the potential to provide energy security, along with environmental and economic benefits. The concept of a hydrogen energy economy was first conceived at The Hydrogen Economy Miami Energy (THEME) Conference, held in March 1974 in Miami, Florida, where the International Association for Hydrogen Energy was established. Forty years later, advances in hydrogen technologies have led the world's most developed countries to invest extensively in preparation for a future hydrogen-based economy. However, the transition from a conventional petroleum-based energy economy to a hydrogen economy involves many uncertainties regarding concerns such as the development of efficient fuel cell technologies, problems in hydrogen production and distribution infrastructure, hydrogen safety issues, and the response of carbon-based fuel markets. This paper presents an assessment of the economic impact of hydrogen energy on the transportation and energy use sectors of Nigeria, along with implications for Greenhouse Gas (GHG) emissions. The analysis uses the Long range Energy Alternatives Planning (LEAP) technology database and model to simultaneously consider the impact of alternative and conventional technologies and fuels on these sectors.
Open Access
Is There a Limit to Nanoscale Mechanical Machining
(Scientific.Net, 2013-10) Oluwajobi, A.O.; Chen, .X
The Moore’s law which predicts that the number of transistors which can be integrated on the computer chip will double every 24 months and which has been the guiding principle for the advancement of the computer industry, is gradually reaching its limit. This is due to the limitations imposed by the laws of physics. Similarly, in the machining sector, Taniguchi predicted an increasing achievable machining precision as a function of time in the 1980s and this prediction is still on course. The question also is, is there a limit to machining and to material removal processes; and how far can this prediction be sustained? In this paper, the molecular dynamics (MD) simulation was employed to investigate this limit in the nanomachining of a copper workpiece with a diamond tool. The variation of the depth of cut used was from 0.01nm to 0.5nm. The Embedded Atom Method (EAM) potential was used for the copper-copper interactions in the workpiece; the Lennard-Jones (LJ) potential was used for the copper-carbon (workpiece-tool interface) interactions and the tool (carbon-carbon interactions) was modelled as deformable by using the Tersoff potential. It was observed from the simulation results that no material removal occurred between 0.01nm – 0.25nm depth. At the depth of cut of 0.3nm, a layer of atoms appears to be removed or ploughed through by the tool. At a depth of cut less than 0.3nm, the other only phenomenon observed was the squeezing of the atom. The 0.3nm depth of cut is around the diameter of the workpiece- copper atom. So, it may be suggested that the limit of machining may be the removal of the atom of the workpiece.
Open Access
Theory of a mechanical method of peeling cassava tubers with knives
(Institute of Agrophysics, 2006-03-27) Adetan, D.A.; Adekoya, L.O.; Aluko, O.B.
A newbut highly promising mechanical cassava peeling concept was investigated. The concept is based on the principle of peel-flesh separation through compression and peel removal with knives. The mechanism of this principle was described and mathematically modelled. Preliminary experiments were carried out on root slices of 100 mm length using a peeling machine developed earlier on the basis of this principle. The data collected were used to validate the model. The model developed predicts the performance index (peel removal efficiency) with a certainty level of 95.46%. Thus, the model adequately explains the peeling concept and it is, therefore, an invaluable and reliable tool for further development and improvement of mechanical cassava peeling machines.

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