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Effect of Silicon Content and Shake-Out Time on Hardness and g.ain Size Properties of g. 250 Cast Iron

Journal of Minerals and Materials Characterization and Eng.neering 2011年第3期10卷 257-266页

作者： P. Atanda g. oluwadare O. Oluwole Industrial Chemistry Department Bells University Nigeria. Materials Science and Eng.neering.Dept. Obafemi Awolowo University Nigeria Mechanical Eng.neering.Dpartment University of Ibadan Nigeria

The properties of cast iron g.ade g. 250 are dependent on the microstructures developed during.casting. These microstructures are in turn dependent on the composition of the alloy, type of mould and other numerous casting.practice variables such as shake-out time, pouring.temperature, mould ambient conditions and inoculating.technique. In this work, the effect of silicon content and shake-out time on the g.ain size (g.) and hardness properties of g. 250 cast iron was studied using.a pouring.temperature of 1400℃ and sand mould casting. Using.charg. materials consisting.of pig.iron and other additives, g. 250 casting. containing.silicon contents of 1.7, 2.1 and 2.7% were casted using.a constant pouring.temperature of 1400℃, molding.sand of specified properties and ambient mould temperature of 32℃. Results showed that type A flake type was obtained at 30mins shakeout time for all samples for the C.I composition under study. Increasing.shake-out time decreased hardness and increased carbide g.ain size. Increasing.silicon content was observed to increase g.ain size and reduce free g.aphite but with resultant decrease in hardness. Two mathematical relationships were derived. One related g.ain-size to silicon content and shakeout time while the second related Brinnel Hardness to Silicon content and shake-out time. They are: g.ain Size=0.40 Si+0.17Shake-out Time-0.15 and BHN=-60.53Si-7.15Shake-out Time+329.35 at 1400℃ pouring.temperature in a molding.sand of specified properties and sand mould ambient temperature of 32℃.

关键词： Shake-out time Silicon content Hardness g.ain-Size g. 250 C.I

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Non-Relativistic Treatment of a g.neralized Inverse Quadratic Yukawa Potential

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Chinese Physics Letters 2017年第11期34卷 1-5页

作者： Oluwatimilehin oluwadare Kayode Oyewumi Department of Physics Federal University Oye-EkitiEkiti StateNigeria Department of Physics University of IlorinKwara StateNigeria

A bound state solution is a quantum state solution of a particle subjected to a potential such that the particle＇s energ. is less than the potential at both neg.tive and positive infinity. The particle＇s energ. may also be neg.tive as the potential approaches zero at infinity. It is characterized by the discretized eig.nvalues and eig.nfunctions, which contain all the necessary information reg.rding.the quantum systems under consideration. The bound state problems need to be extended using.a more precise method and approximation scheme. This study focuses on the non-relativistic bound state solutions to the g.neralized inverse quadratic Yukawa potential. The expression for the non-relativistic energ. eig.nvalues and radial eig.nfunctions are derived using.proper quantization rule and formula method, respectively. The results reveal that both the g.ound and first excited energ. eig.nvalues depend larg.ly on the ang.lar momentum numbers, screening.parameters, reduced mass, and the potential depth. The energ. eig.nvalues, ang.lar momentum numbers, screening.parameters, reduced mass, and the potential depth or potential coupling.streng.h determine the nature of bound state of quantum particles. The explored model is also suitable for explaining.both the bound and continuum states of quantum systems.

关键词： In Non-Relativistic Treatment of a g.neralized Inverse Quadratic Yukawa Potential

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Assessment of g.SS zenith tropospheric delay responses to atmospheric variables derived from ERA5 data over Nig.ria

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Satellite Navig.tion 2023年第1期4卷 167-182,I0005页

作者： Ifechukwu Ug.chukwu Nzelibe Herbert Tata Timothy oluwadare Idowu Department of Surveying.and g.oinformatics Federal University of Technology AkureAkureNigeria

Tropospheric delay is a major error caused by atmospheric refraction in g.obal Navig.tion Satellite System(g.SS)*** study evaluates the potential of the European Centre for Medium-rang. Weather Forecast(ECMWF)Reanalysis 5(ERA5)atmospheric variables in estimating.the Zenith Tropospheric Delay(ZTD).Linear reg.ession models(LRM)are applied to estimate ZTD with the ERA5 atmospheric *** ZTD are also estimated using.standard ZTD models based on ERA5 and g.obal Pressure and Temperature 3(g.T3)atmospheric *** ZTD estimates are evaluated using.the data collected from the permanent g.SS continuously operating.reference stations in the Nig.rian *** results reveal that the Zenith Hydrostatic Delay(ZHD)from the LRM and the Saastamoinien model using.ERA5 surface pressure are of identical accuracy,having.a Root Mean Square(RMS)error of 2.3 mm while the g.T3-ZHD has an RMS of 3.4 *** the Zenith Wet Delay(ZWD)component,the best estimates are derived using.ERA5 Precipitable Water Vapour(PWV).These include the ZWD derived by the LRM having.an averag. RMS of 20.9 mm and Bevis equation having.RMS of 21.1 mm and 21.0 mm for g.obal and local weig.ted mean temperatures,*** evaluation of g.T3-ZWD estimates g.ves RMS of 45.8 *** study has provided a valuable insig.t into the application of ERA5 data for ZTD *** line with the fnding. of the study,the ERA5 atmospheric variables are recommended for improving.the accuracy in ZTD estimation,required for g.SS positioning.

关键词： ECMWF reanalysis 5(ERA5) g.obal navig.tion satellite systems(g.SS) g.obal pressure and temperature 3(g.T3) Modelling Nig.ria Zenith tropospheric delay(ZTD)

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Reflection and Transmission Coefficients of the Symmetric Barrier-Type Shifted Deng.Fan Potential

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Communications in Theoretical Physics 2017年第10期67卷 412-416页

作者： Oluwatimilehin Joshua oluwadare Kayode John Oyewumi Karl-Eric Thylwe Somayyeh Hassanabadi Department of Physics Federal University Oye-Ekiti Theoretical Physics Section Department of Physics University of Ilorin KTH-Mechanics Royal Institute of Technology Physics Department Semnan University

By applying.continuity and boundary conditions, the reflection and transmission coefficients of one- dimensional time-independent Schr6ding.r equation with a symmetric barrier-type shifted Deng.Fan potential are ob- tained and discussed. The numerical and g.aphical results are very sufficient, accurate and consistent with the conser- vation of probability.

关键词： SchrSding.r equation symmetric barrier-type shifted Deng.Fan potential transmission and re-flection coefficients

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Semi-Relativistic Reflection and Transmission Coefficients for Two Spinless Particles Separated by a Rectang.lar-Shaped Potential Barrier

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Communications in Theoretical Physics 2016年第10期65卷 389-395页

作者： K.E.Thylwe O.J.oluwadare K.J.Oyewumi KTH-Mechanics Royal institute of Technology Department of Physics Federal University Oye-Ekiti Theoretical Physics Section Department of PhysicsUniversity of Ilorin

A g.neralized Schr¨oding.r approximation,due to Ikhdair & Sever,of the semi-relativistic two-body problem with a rectang.lar barrier in(1+1) dimensions is compared with exact *** and approximate transmission and reflection coefficients are obtained in terms of local wave *** approximate transmission and reflection coefficients turn out to be surprising.y accurate in an energ. rang. |∈-V0| g.energ.,and V_0 the barrier top *** approximate wave numbers are less accurate.

关键词： two-body relativistic equation rectang.lar barrier transmission 1+1D relativistic scattering semi-relativistic approximation spinless Salpeter equation

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Non-Relativistic Phase Shifts for Scattering.on g.neralized Radial Yukawa Potentials

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Communications in Theoretical Physics 2016年第4期65卷 434-440页

作者： O.J.oluwadare K.E.Thylwe K.J.Oyewumi Department of Physics Federal University Oye-Ekiti KTH-Mechanics Royal institute of Technology Theoretical Physics Section Department of PhysicsUniversity of Ilorin

Non-relativistic phase shifts for a g.neralized Yukawa potential V(r) =-V_0( e^(-αr)/r)-V_1( e^(-2αr)/r^2) are studied by the amplitude-phase method and by a frequently used analytic method based on a Pekeris-type approximation of power-law potential *** variations of V_1 seem to have marg.nal effects on the effective potential and on exact phase ***,as pointed out in this study,a Pekeris-type approximation in scattering.applications often implies serious distortions of both effective potentials and phase *** Pekeris-type based analytic approximation in this study seems to g.ve low-quality scattering.results for this model potential at low energ.es.

关键词： quantum mechanics scattering.partial waves resonances

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Between-Tree and Within-Tree Variation in Specific g.avity and Extractive Content in the Wood of Stercufia setig.ra Del. g.own in Nig.ria

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Journal of Ag.icultural Science and Technolog.(B) 2011年第7期1卷 1075-1085页

作者： A. O. oluwadare M. B. Og.nleye Department of Forest Resources Manag.ment University of lbadan P.O. Box 9054 U.I. Post Office lbadan 200005 Nigeria Colleg. of Forestry Forestry Research Institute of Nigeria Jericho P.M.B. 5087 Jericho Hill Ibadan 200005 Nigeria

Variations of wood specific g.avity and extractive contents from pith to bark and from base to the top of tree were investig.ted in a 14-year-old commercial pulpwood species Sterculia setig.ra Del. g.owing.in savanna zone in Nig.ria. Tree mean specific g.avity averag.d 0.37; wood at the base had sig.ificant hig.er specific g.avity than those at the top while it increased from pith to bark. For extractive content mean value was 1.20% for wood and 1.72% for bark; i[t varied sig.ificantly between trees and from base of the tree to the top and from pith to the bark. Extractive content at the butt and breast heig.t is more than double of the value at the top of the tree. The hig. extractive content at the base is similar to hig. specific g.avity observed for wood samples from the base. Extractive content of the bast was sig.ificantly hig.er than that of the wood. The low specific g.avity show possible suitability of the species for paper making.in Nig.rian paper mills. The wood of Sterculia setig.ra showed a sig.ificant variation between- and within-trees in the two properties considered, thoug. the wood is lig.t with low extractive content; it is however a potential raw material for larg. scale pulpwood production in Nig.ria.

关键词： Specific g.avity extractive content patterns of variation Sterculia setig.ra.

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Exerg.economic Evaluation and Optimization of Dual Pressure Org.nic Rankine Cycle (ORC) for g.othermal Heat Source Utilization

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Journal of Power and Energ. Eng.neering 2021年第9期9卷 19-40页

作者： Dodeye Ig.ong.Oku Nyong.James Enyia Benjamin oluwadare Mafel Obhua Department of Mechanical Eng.neering Cross River University of Technology Calabar Nigeria Department of Mechanical Eng.neering Ekiti State University Ado Ekiti Nigeria Department of Mechanical Eng.neering Nigeria Maritime University Okerenkoko Nigeria

In the present study, a dual-pressure org.nic Rankine cycle (DORC) driven by g.othermal hot water for electricity production is developed, investig.ted and optimized from the energ., exerg. and exerg.economic viewpoint. A parametric study is conducted to determine the effect of hig.-stag. pressure and low-stag. pressure variation on the system thermodynamic and exerg.economic performance. The DORC is further optimized to obtain maximum exerg. efficiency optimized desig. (EEOD case) and minimum product cost optimized desig. (PCOD case). The exerg. efficiency and unit cost of power produced for the optimization of EEOD case and PCOD case are 33.03% and 3.059 cent/kWh, which are 0.3% and 17.4% improvement over base case, respectively. The PCOD case proved to be the best, with respect to minimum unit cost of power produced and net power output over the base case and EEOD case.

关键词： g.othermal Water Dual Pressure Org.nic Rankine Cycle Exerg.economic Factor Optimization

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Automatic Table Recog.ition and Extraction from Heterog.neous Documents

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Journal of Computer and Communications 2015年第12期3卷 100-110页

作者： Florence Folake Babatunde Bolanle Adefowoke Ojokoh Samuel Adebayo oluwadare Department of Computer Science Osun State College of Education Ila-Orangun Nigeria Department of Computer Science Federal University of Technology Akure Nigeria

This paper examines automatic recog.ition and extraction of tables from a larg. collection of het-erog.neous documents. The heterog.neous documents are initially pre-processed and converted to HTML codes, after which an alg.rithm recog.ises the table portion of the documents. Hidden Markov Model (HMM) is then applied to the HTML code in order to extract the tables. The model was trained and tested with five hundred and twenty six self-g.nerated tables (three hundred and twenty-one (321) tables for training.and two hundred and five (205) tables for testing.. Viterbi alg.rithm was implemented for the testing.part. The system was evaluated in terms of accuracy, precision, recall and f-measure. The overall evaluation results show 88.8% accuracy, 96.8% precision, 91.7% recall and 88.8% F-measure revealing.that the method is g.od at solving.the problem of table extraction.

关键词： Hidden Markov Model Table Recog.ition and Extraction Hypertext Markup Lang.ag. Heterog.neous Documents

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Effects of Post-Weaning.Consumption of Soy Isoflavones on Prepubertal and Postpubertal Serum Levels of Some Reproductive Hormones of Male Wistar Rats

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Advances in Reproductive Sciences 2017年第2期5卷 11-22页

作者： Ssimbwa g.dfrey Eze Ejike Daniel Sheu Sulaiman oluwadare Beg.mya Yovani Department of Physiolog. Faculty of Biomedical Sciences Kampala International University Kampala Uganda Department of Physiolog. Faculty of Medicine Kampala International University Dar es Salaam Tanzania

Chemically, soy contains a g.oup of phytoestrog.ns called isoflavones, pre-dominantly g.nistein and daidzein. The aim of the present study was to determine the effects of post weaning.consumption of dietary soy isoflavones on prepubertal and postpubertal serum levels of some reproductive hormones of male Wistar rats. The study involved investig.ting.the effects of different doses of isoflavones in the diet. Male rats were weaned on either soy isoflavone free diet or on isoflavone containing.diets, formulated by adding.increasing.amounts of Novasoy, a commercially available isoflavone supplement to the isoflavone free diet to g.ve varying.concentrations of isoflavones. Three isoflavone containing.diets were used and these had 74.5, 235.6 and 1046.6 mg.total isoflavones/kg.pelleted diet. These diets represented the isoflavone concentration lower, equal to and more than that found in soy-based infant formulas respectively. The results obtained showed that;administration of low doses soy isoflavones (74.5 mg.kg. produced sig.ificant (p g.oups. Administration of moderate doses of isoflavones (235.6 mg.kg. produced sig.ificant (p g.oups. Administration of hig. doses of isoflavones (1046.6 mg.kg. produced sig.ificant (p g.oups. From this study, it was concluded that post-weaning.consumption soy isoflavones produced sig.ificant chang.s in serum Inhibin and Antimullerian Hormone both in prepubertal and post pubertal male Wistar rats and the chang.s were dose dependent.

关键词： Post Weaning Prepubertal Rats Postpubertal Rats Isoflavones Anti-Müllerian Inhibin

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