Theses and Dissertations (Civil Engineering)
http://repository.unn.edu.ng/handle/123456789/175
2019-06-18T07:57:34ZAppraisal Of Construction Health And Safety Risk Management In Nigerian Construction Industry – A Case Study Of The Building Industry
http://repository.unn.edu.ng/handle/123456789/5999
Appraisal Of Construction Health And Safety Risk Management In Nigerian Construction Industry – A Case Study Of The Building Industry
Okechukwu, Ifeoma Claris
The study examined the state of health and safety risk management practices in the building sector of the construction industry and has the objectives to: evaluate the construction risks inherent in the building sector of the construction industry; examine the health and safety risk management processes adopted by the construction industry in Nigeria; validate the existence of identified factor(s) militating against the implementation of health and safety practices in the construction industry in Nigeria; and investigate if there are established frameworks for effective health and safety risk management in the construction industry of Nigeria. The study adopted the survey and case study research design. It employed the use of Delphi’s technique in the distribution of questionnaire and made use of chi-square analytical technique for the analysis of gathered data. The findings revealed that: most of the parties involved in construction projects do not have any significant health and safety risk management process in place; the identified factors militating against the implementation of health and safety risk management practices are still valid; there is no existing established framework for effective regulation of health and safety risk management practices. Various improvement strategies have been suggested.
2014-08-01T00:00:00ZEffects Of Addition Of Carbide On Sewage Degradation
http://repository.unn.edu.ng/handle/123456789/5998
Effects Of Addition Of Carbide On Sewage Degradation
Okah, Michael Chukwu
The objective of this research is to investigate the effect of addition of carbide on sewage degradation. To provide answers to the above objective, some laboratory tests were conducted which include Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total coliform, pH and Suspended Solids (SS) tests. Six experimental set ups of 5liters of sewage were constructed in the laboratory under anaerobic condition. Each of the sewage contained 0g (which served as control), 1g, 2g, 5g, 8g and 10g of fresh calcium carbide. Samples were collected twice per week for two months for the laboratory tests. The results from the tests showed that there was a gradual increase in the percentage of COD and BOD efficiency removal as the quantity of carbide added increased with time. Also, the number of positive coliform bacteria decreased as the quantity of carbide added increased with time. There was also a gradual increase in suspended solid as the quantity of carbide added increased. pH value increased as the quantity of carbide added increased with time. This could be due to the assumed calcium hydroxide produced from the reaction of sewage with calcium carbide since calcium hydroxide is a base. Calcium carbide can therefore be used in the reduction of BOD, COD and coliform bacteria in sewage.
2014-02-01T00:00:00ZIntegrated Solar And Hydraulic Jump Enhanced Waste Stabilization Pond
http://repository.unn.edu.ng/handle/123456789/5997
Integrated Solar And Hydraulic Jump Enhanced Waste Stabilization Pond
Ogarekpe, Nkpa Mba
This study on the integrated solar and hydraulic jump enhanced waste stabilization pond (ISHJEWSP) is aimed at determining the effect of variations in solar radiation, hydraulic jump, hydro-kinematic factors and pond geometry, on the treatment efficiency of wastewater in the ISHJEWSP. An equation to account for these effects was derived, calibrated and verified. An empirical regression model for the prediction of the Biochemical Oxygen Demand (BOD5) in the ISHJEWSP for sewage treatment was also developed. Three sets of experimental ponds with varying locations of slopes were constructed using metallic tanks with each set consisting of eight numbers of ponds with varying width. Also, solar reflectors were constructed to increase the incident sunlight intensity. Wastewater samples collected from the inlet and outlet for varying inlet velocities of the ISHJEWSPs were examined for physicochemical and biological characteristics for a period of nine months. The parameters examined were temperature, pH, detention time, dissolved oxygen, total coliform count, total suspended solids, E-coli, algae concentration, BOD5 and tracers studies. The efficiencies of the ISHJEWSPs with respect to these parameters fluctuated with variations in solar radiation, width, inlet velocity and location of point of initiation of hydraulic jump with the smallest ISHJEWSP in width giving the highest treatment efficiency at higher intensities of solar radiation. It was generally observed that the treatment efficiencies of the ISHJEWSPs increased as the location of the point of initiation of the hydraulic jump decreased relative to the inlet and with increase in inlet velocity for all sets studied though with precedence to solar radiation and temperature. A comparison of the conventional WSP and the ISHJEWSP showed that the bacteria removal was significantly higher in the ISHJEWSP than the conventional pond at a significance level of 5%. The verification of the conventional model gave a good average coefficient of correlation of R = 0.800 (0.713 to 0.891) between the measured and calculated Ne/No with an average standard error of 0.173 (0.157 to 0.224) and average R = 0.924(0.858 to 0.965) and average standard error of 0.034 (0.010 to 0.060) for the ISHJEWSP, respectively. An empirical model was developed to predict the BOD5 in the ISHJEWSP based on the independent variables of pH, temperature, algae concentration, dissolved oxygen, inlet velocity, location of point of initiation of hydraulic jump, angle of inclination causing hydraulic jump and intensity of solar radiation. The empirical regression model developed gave a good multiple regression coefficient of correlation of 0.938 with a standard error of 5.224 at a significance level of 10%.
2015-05-01T00:00:00ZAnalysis Of Orthotropic Plates In Free Vibration Regime Using Rayleigh – Ritz Method
http://repository.unn.edu.ng/handle/123456789/5996
Analysis Of Orthotropic Plates In Free Vibration Regime Using Rayleigh – Ritz Method
Jamesime, Emmanuel
The assumed deflection shapes used in the approximate methods such asin the Rayleigh Ritz method were normally formulated by inspection andsometimes by trial and error, until recently, when a systematic method ofconstructing such a function in the form of characteristic orthogonal polynomials(COPs) was developed in 1985. However, vibrational analyses of plates with all edges free or clamped are much more complicated. This project aims at establishing particular expressions for the fundamental natural frequency of rectangular plates using Rayleigh Ritz Method by obtaining approximate shape functions of plate of different support conditions through characteristics orthogonal polynomials. To this end, new sets of stress – strain relations for orthotropic plates were derived. The principle of force of inertia was introduced, yielding the corresponding dynamic governing equation of orthotropic plate and hence the strain energy equation of orthotropic plate.Rayleigh – Ritz quotient was obtained by equating the strain energy
equation of the plate to the kinetic energy equation of the plate. From the rayleigh’s quotient, an expression for the natural frequency of the plate was obtained in terms of the shape functions of the plate. The shape function of plate of different support conditions was obtained through characteristics orthogonal polynomials. A spreadsheet programme was developed to aid the solutions of the equations and the results show that values of fundamental natural frequencies obtained using the present studies (Rayleigh - Ritz Method) for all round clamped plates with aspect ratio, r between 0.5 to 1.2 are four times greater than that obtained from that of previous studies (Galerkin’s method). Moreso, for plates with mixed support conditions, values of fundamental natural frequencies obtained using the present study are higher than that of previous studies (Galerkin’s Method) their difference ranging from 33% for r = 0.5 to 95% for r = 1.2 while results for plate all round simply supported for both present and previous studies are the same.
2014-08-01T00:00:00Z