Browsing by Author "Makinde, Oluwole D."

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    Equal channel angular pressing technique for the formation of ultra-fine grained structures
    (Academy of Science of South Africa, 2012-10-02) Sanusi, Kazeem O.; Makinde, Oluwole D.; Oliver, Graeme J.
    ENGLISH ABSTRACT: Equal channel angular pressing is one of the techniques in metal forming processes in which an ultra-large plastic strain is imposed on a bulk material in order to make ultra-fine grained and nanocrystalline metals and alloys. The technique is a viable forming procedure to extrude materials by use of specially designed channel dies without substantially changing the geometry by imposing severe plastic deformation. This technique has the potential for high strain rate superplasticity by effective grain refinement to the level of the submicron-scale or nanoscale. Wereview recent work on new trends in equal channel angular pressing techniques and the manufacturing of die-sets used for the processing of metals and alloys. We also experimented on a copper alloy using the equal channel angular pressing technique to examine the microstructural, mechanical and hardness properties of the ultra-fine grained and nanocrystalline materials produced. After deformation, all samples were subjected to a hardness test and the results showed improved mechanical behaviour of the ultra-fine grained copper alloy that was developed. This research provides an opportunity to examine the significance of the equal channel angular pressing process for metals and alloys. That is, these ultra-fine grained materials can be used in the manufacturing of semi-finished products used in the power, aerospace, medical and automotive industries.
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    Mixed convective flow of a visco elastic fluid between two porous parellel plates
    (Blue Eyes Intelligence Engineering and Sciences Publication, 2019) Kumar, D. Satish; Murthy, C. H. V. Ramana; Anusha, S.; Makinde, Oluwole D.
    A diagnostic answer for the problem of sincerely grew loose convective circulation between two vertical parallel plates has been inspected in this paper. The trademark highlights of various parameters were talked about in element. it's miles considered that to be the Grashoff huge variety declines, the profiles are more and more illustrative in nature. Likewise, due to the fact the Grashoff range reductions the charge of the liquid medium increments. it is found that, the pinnacle pace is type of organized at a median separation most of the circulate geometry. similarly, as the Grashoff amount reductions, the imply essential thrust gives off an influence of being step by step main as impact of which the liquid movements quicker within the middle locale. Likewise, it is visible that, the speed increments because the Prandtl quantity discounts. in addition, it is considered that to be the Prandtl variety expands the mass transition diminishes. The mass transition is absolutely constrained thru the parameters, for instance, Reynolds range and Prandtl amount. The flow into supporter in each the instances does no longer differs lots. All above said outcomes and delineations accommodate with the outcomes built up by manner of M. Sajid, I. Pop, T. Hayat
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    Optimal control of HIV/AIDS in the workplace in the presence of careless individuals
    (Hindawi Publishing Corporation, 2014-06-26) Seidu, Baba; Makinde, Oluwole D.
    A nonlinear dynamical system is proposed and qualitatively analyzed to study the dynamics of HIV/AIDS in the workplace. The disease-free equilibrium point of the model is shown to be locally asymptotically stable if the basic reproductive number, R0, is less than unity and the model is shown to exhibit a unique endemic equilibrium when the basic reproductive number is greater than unity. It is shown that, in the absence of recruitment of infectives, the disease is eradicated when R0 < 1, whiles the disease is shown to persist in the presence of recruitment of infected persons. The basic model is extended to include control efforts aimed at reducing infection, irresponsibility, and nonproductivity at the workplace. This leads to an optimal control problem which is qualitatively analyzed using Pontryagin’s Maximum Principle (PMP). Numerical simulation of the resulting optimal control problem is carried out to gain quantitative insights into the implications of the model. The simulation reveals that a multifaceted approach to the fight against the disease is more effective than single control strategies.
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    Second law analysis for MHD permeable channel flow with variable electrical conductivity and asymmetric Navier slips
    (De Gruyter, 2014-11) Eegunjobi, Adetayo S.; Makinde, Oluwole D.
    The inherent irreversibility in a steady hydromagnetic permeable channel flow of a conducting fluid with variable electrical conductivity and asymmetric Navier slip at the channel walls in the presence of induced electric field is theoretically investigated. The model nonlinear governing equations are obtained and numerically solved using shooting quadrature. Numerical results for velocity and temperature profiles are utilised to compute the entropy generation number and the Bejan number. Pertinent results are displayed graphically and discussed quantitatively.
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    Thermodynamics analysis of variable viscosity hydromagnetic Couette flow in a rotating system with Hall effects
    (MDPI, 2015-11-20) Makinde, Oluwole D.; Eegunjobi, Adetayo S.; Tshehla, M. Samuel
    In this paper, we employed both first and second laws of thermodynamics to analyze the flow and thermal decomposition in a variable viscosity Couette flow of a conducting fluid in a rotating system under the combined influence of magnetic field and Hall current. The non-linear governing differential equations are obtained and solved numerically using shooting method coupled with fourth order Runge–Kutta–Fehlberg integration technique. Numerical results obtained for velocities and temperature profiles are utilized to determine the entropy generation rate, skin fictions, Nusselt number and the Bejan number. By plotting the graphs of various values of thermophysical parameters, the features of the flow characteristics are analyzed in detail. It is found that fluid rotation increases the dominant effect of heat transfer irreversibility at the upper moving plate region while the entropy production is more at the lower fixed plate region.