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Computational Approach to Modelling Fracture Behaviour of Polypropylene/Talc Composites  [PDF]
Chinedum Ogonna Mgbemena, ObuoraAnozie Okoye
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2012, DOI: 10.4236/jmmce.2012.118076
Abstract: Fracture represents one of the major problems associated with the selection and use of engineering materials for high temperature applications. The fracture toughness is of special relevance on the design of components. In this work, the fracture behavior of Polypropylene/Talc composites was studied. From the results of the tensile and flexural tests conducted on the composite, scatter diagrams were made using Microsoft Excel to evaluate and show the effect of the addition of the talc filler as it affects the tensile strength, percentage elongation at break, flexural strength and modulus. In order to give additional analysis, the talc filler content effect was presented mathematically to further describe explicitly the various equations associated with each scatter diagram earlier developed using Microsoft Excel. The mathematical expression developed shows the actual talc filler content on the fracture mechanical properties of the sample composite.
Effects of Reinforcement Combinations of Calcium Carbonate Nanofiller on the Mechanical and Creep Properties of Polypropylene  [PDF]
Chris Chukwutoo Ihueze, Chinedum Ogonna Mgbemena
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.910065
Abstract: This paper investigated the effects of calcium cabonate nanofiller on the mechanical behavior of homo polypropylene by conducting tensile and creep tests. The Young’s Modulus of the nanocomposite showed some improvement with the incorporation of the calcium carbonate nano-filler while the tensile strength deteriorated. The stearic acid coated fillers showed the highest improvement in the above tensile properties at low volume fractions not exceeding 0.10 while the deformation rate increases with the inclusion of the nanofiller. The creep parameters evaluated include optimum elastic modulus estimated as 2GPa at 10% volume fraction, creep rate at ambient as 0.004-0.043hr-1, and creep limit at ambient as 60-113MPa as opposed to the tensile strength of PPC predicted as 45MPa for treated and 37.5MPa for untreated, all as against 123MPa for neat and unreinforced PP, though at 0.05 volume fraction the tensile strength was evaluated as 140MPa and 133.3MPa for coated and uncoated PPC respectively.
Creep Function Parameter Analysis for Optimum Design with Calcium Carbonate Nanofiller – Polypropylene Composite  [PDF]
Christopher Chukwutoo Ihueze, Chinedum Ogonna Mgbemena, E.E. Nnuka
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.101003
Abstract: This paper is about the use of power law model to fit experimental creep data of PP reinforced with calcium carbonate nanofiller at 10% optimum volume fraction with a view to characterizing the new material (PPC2) parametrically. The creep parameters were evaluated for neat (PPC0) and reinforced PP (PPC2) to establish the influence of reinforcement on the creep variables like creep rate and creep activation energy. The coefficient parameter A estimated within the stress level range 13.08MPa-22.88MPa has the range 0.0165-0.0651 while the exponent parameter n has 0.299-0.370. The creep stress coefficient K and exponent m has the respective values 161.495 and 0.3288 for PPC0 and 1881.4965 and 0.5448 for PPC2. The value of the parameter p similar to Larson-Miller has the value 4014.1871. Two creep function models used found that PPC0 has higher activation energy with value 9.3642E-20 J/mol for the stress 13.08MPa and PPC2 has values for the stresses 13.08MPa, 19.61MPa and 22.88MPa as 5.55998E- 20J/mol,5.4573E-20J/mol and 4.845E-20J/mol respectively. Of the two master curves produced, that following Larson-Miller parameter is recommended as the relationship between lnσ and parameter f(σ) is relatively linear and will give better results than the curve assumed to follow Sherby-Dorn that will give average result.
The Influence of Creep on the Mechanical Properties of Calcium Carbonate Nanofiller Reinforced Polypropylene  [PDF]
Chrisopher Chukwutoo Ihueze, Chinedum Ogonna Mgbemena, Ugwu Sylveste
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.102010
Abstract: The study focused on experimental and classical data to establish some mechanical properties for optimum design of new polypropylene components to serve under creep environment. The creep studies recorded stress limits that never exceeded 24.19MPa and maximum creep modulus that never exceeded 1.49GPa as against the predictions of classical equations that gave 2.0GPa for PPC0 and 2.46GPa for PPC2 at ambient conditions. The shear modulus and shear strength of the PPC0 and the PPC2 are predicted as 0.75GPa and 120MPa respectively and 0.92GPa and 150MPa respectively while the yield strengths found to be about 13.19MPa and 13.20MPa respectively for PPC0 and PPC2 at elastic strains 0.008 and 0.009 respectively. Further found are that as the material deforms the stiffness or modulus decrease, at low strains there is an elastic region, as temperature and applied stress increase the material becomes more flexible characterized with reduction in moduli. Plastic deformation at strains above 0.01 resulted to strain- hardening or strain-strengthening that manifested as the increasing area ratios and associated creep cold work. Also established by this study is a computational model for evaluating the elastic modulus of polypropylene matrix based material as expressed in equation (6). Both the Halphin-Tsai and the Birintrup equations for elastic modulus of unidirectional fibre composites were confirmed to be appropriate for prediction of elastic modulus of nanofiller composites with polymer matrix.
International Journal of Engineering Science and Technology , 2010,
Abstract: This paper seeks to establish queueing models that can help organizations to improve on their customer service within and outside their establishment. New Models were created using non linear regression analysis which is more convenient for the organizations to assess. It was found that The Coefficient of determination, R2 value equals 1 and that the Degree of Correlation is 100% which indicates that 100% of the original uncertainty has been explained by the model.Therefore, the model clearly indicates that the Nonlinear Regression approach can be used to model the queueing system of any organization for improved efficiency.
Thermal Cycling Effects on the Fatigue Behaviour of Low Carbon Steel  [PDF]
Segun Afokhainu Agbadua, Chinedum Ogonna Mgbemena, Chika Edith Mgbemena, Lazarus Onyebuchi Chima
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.1014106
Abstract: This paper examines the behavior of low carbon steels subjected to a frequency thermal cycling test. A compositional analysis was performed to ascertain the percentage of carbon in the asreceived materials. The specimens were machined to a precise gauge length and diameter and exposed to various cycles of heat at each temperature. A fatigue test was also performed with the use of Avery Dennison and bending stress was obtained using the curve supplied with the machine. The results from the machine were converted to Mega Pascal (MPa) and the values used to plot S-N curves and fatigue resistance for the specimens at various cycles and different temperatures were established.
Thermal Behavior and UV Properties of Organomodified Kaolin Oleochemically Derived from Rubber Seed Oils (Hevea brasiliensis) and Tea Seed Oils (Camellia sinensis)  [PDF]
Chinedum Ogonna Mgbemena, Naboth O. Ibekwe, Abdul Azeez Peer Mohamed, Rugmini Sukumar, Aryiappallil Ramankuttymenon Ravindranatha Menon
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2013, DOI: 10.4236/jsemat.2013.33021

Kaolin was modified using a chemical complex of hydrazine hydrate and oleochemical sodium salts derived from rubber seed oil (SRSO) and tea seed oil (STSO) respectively. Characterization of the pristine kaolin and the modified kaolins were performed using Scanning Electron Microscopy (SEM), Simultaneous Thermogravimetric/Differential Thermal Analysis (TG/DTA) and UV Spectrophotometry. TG/DTA revealed that the incorporation of the oleochemical salts enhanced thermal decomposition of kaolin into metakaolin. Ultraviolet spectrophotometric studies conducted on the modified kaolin show for the first time that the SRSO-modified kaolin and STSO-modified kaolin have a peak absorbance wavelengths of 312.72 nm and 314.26 nm respectively. This shows that the modified kaolin is a promising candidate for sunscreen applications.

Optimum Reliability and Cost of Power Distribution System: a case of Power Holding Company of Nigeria
Chinwuko Emmanuel Chuka,Prof. Uba Nwuba,Mgbemena Chinedum Ogonna
International Journal of Engineering Science and Technology , 2011,
Abstract: This paper presents a holistic approach towards the sustainability of power distribution system through the application of operations research evaluation technique. The approximate cost of energy loss, substation cost, feeder cost and outage cost was developed using dynamic programming technique with the aim of optimizing the costs. The optimization programme minimized the total costs of the distribution system as the objective function by determining the optima of the number locations and power of the substations, the routes of the feeders and the power losses within the network subject to a set of constraints. This study contributed significantly in analyzing the variable costs of substations.
Electricity Generation and Distribution in Nigeria: Technical Issues and Solutions
Chinwuko Emmanuel C,Mgbemena,Chinedum O,Aguh
International Journal of Engineering Science and Technology , 2011,
Abstract: This paper attempts to address the problem of extreme electricity shortage in Nigeria. This deficiency is multidimensional which are attributed to inadequate infrastructure, inadequate funding of this sector, and energy losses from generation to billing. Some technical issues were raised and solutions proffered taking the Awka business unit of Power Holding Company of Nigeria, (PHCN) as a case. It was suggested that the actual load demand of the PHCN Awka business unit which at present is 135.12MVA be increased to 150MVA by building new substations to accommodate this proposed new load demand. This new distribution system should be able to handle the present need of the Awka Business Unit of 135.12MVA with a margin capacity of 14.88MVA for future expansion. This when fully implemented will ensure constant and adequate power supply in Awka and its environs.
Microbial resistance to antibiotics
IE Chinedum
African Journal of Food, Agriculture, Nutrition and Development , 2004,
Abstract: Organisms that are normally sensitive to the action of an antibiotic may sometimes develop resistance or insensitivity to it. This, they may do through destroying the antibiotic or by retaining their growth even in the presence of the drug. Microbial resistance to antibiotics is now widespread and poses a serious clinical threat. Microorganisms develop resistance to antibiotics by any of the following mechanisms: selection, mutation, phage transduction, and transference while microbial resistance can either be inherent in the organism or acquired through the environment. Factors that have led to the continued occurrence of bacterial resistance to antimicrobial agents include: over prescription of antibiotics, use of under dose, prescribers’ irrational attitudes, patients’ demands, inappropriate advertisements and use of antibiotics in agriculture. Microbial resistance to antibiotics can thus be minimized through proper enlightenment, more rational antibiotic selection during treatment and proper legislation.
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