LAUTECH Journal of Engineering and Technology (LAUJET)
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ANALYSIS OF THE CAUSES OF FAILURE OF A STOREY BUIDING ALONG OSUN STATE UNIVERSITY ROAD, OSOGBO.
Get PDFAbstract Building collapse has become a very common occurrence in Nigeria. For this current study, relevant analysis cum investigations carried out on a collapsed building along Osun State University Road, Osogbo include site reconnaissance survey, soil test, particle size distribution and non-destructive test of the remaining debris of the structural elements of the collapsed building. The results show that the building was under designed in critical areas of the building elements such as; columns, beams, and slabs. Also, investigation reveals that the client did not employ qualified personnel to provide detailed working drawing and thorough supervision which contributed majorly to the collapse of the building. Results also show that the fine and coarse aggregate used were uniformly graded, thereby satisfying the requirement of BS EN 12620 (2008) for fine and coarse aggregate used for the building concrete. This study observed importantly that the characteristic compressive strength; fcu = (20N/m) recommended for reinforce-concrete was not met by the constructors. It is therefore concluded that lack of detailed working drawings, supervision, use of inappropriate sandcrete block, poor concrete production, improper reinforcement placement among others, contributed to the collapse of the building
EFFECT OF MIXING RATIO ON BUBBLING PRESSURE OF POROUS CERAMIC DISCS PRODUCED WITH SAW DUST AS THE BURNT OUT MATERIAL
Get PDFThe control of the amount of burnt out material in production of porous ceramics is important for the attainment of the desired pore size distribution which influences other characteristics such as bubbling pressure. Five different mixing percentage ratios of sawdust burnt out material to kaolinite clay, of 10:90, 20:80, 30:70, 40:60, 50:50 by volume, were therefore used in the moulding of porous ceramic discs 10.2 cm in diameter and 1.5 cm thickwhich were fired in a kiln to 1100 oC. The bubbling pressuresof three replicate discs per mixing ratiowere determined by the gas transport method. The corresponding sawdust content of the mixtures by weight were found to be3.33, 7.19, 11.72, 17.12 and 23.65 % respectively. Average bubbling pressure of the discs was found to vary inversely with sawdust content of the mixture and rangedfrom 10.33 MPa for the 50:50 Mixture to 66.33 MPa for the 10:90 Mixture. The regression relationship between the average bubbling pressures (MPa) and Mixture sawdust content by weight (%) was found to be best described in form of a decaying power function with a coefficient of determination of 0.986. It was therefore suggested that regression relationship could be useful in the specification of sawdust-kaolinite clay mixtures for the production of porous ceramics discs for special applications
ASSESSMENT OF MAINTENANCE AND FACILITY SAFETY IN SOME SELECTED MANUFACTURING INDUSTRIES IN NIGERIA
Get PDFThe maintenance of equipment and safety of facilities is very important to an industry as it determines its performance. This study aims to evaluate the effectiveness and efficiency of safety and mainte*nance practices to ensuring overall operational performance of some selected manufacturing industries in Nigeria. This paper evaluated the maintenance and safety practices of selected manufacturing industries in Ibadan, Oyo state, Nigeria. It investigated the causes of breakdown, causes of accident and predicted the impact of maintenance and safety practice on production. Questionnaire and personal interaction were employed to collect data on record of maintenance and safety practices, annual record of accidents and machine breakdown from nine manufacturing industries within Ibadan metropolis in Oyo State Nigeria. These were analyzed using existing mathematical models. Equipment maintainability, reliability, availability and causes of equipment breakdown, and accident were evaluated. Results revealed that average maintainability, reliability and availability were 0.648462, 0.764162 and 0.807242 respectively. Average overall economic implications of minor and serious accidents are#533,324,134 and #896,950,921, respectively. Causes of breakdown were identified to be excess workload, failure of parts, untrained operator and inadequate maintenance while unsafe condition and act are responsible for accident occurrences. The Maintenance, safety culture, planning and management in manufacturing industries need more improvement, in order to ensure waste reduction, optimized operational cost, increased productivity and efficiency. Dynamic development of safety legislations from government is encouraged
OPTIMISATION OF HIDDEN MARKOV MODEL FOR DISTRIBUTED DENIAL OF SERVICE ATTACK PREDICTION USING VARIATI ONAL BAYESIAN
Get PDFDistributed Denial of Service (DDoS), is a coordinated attack that is majorly carried out on a massive scale against the availability of services property of a target system or network resources. Due to the continuous evolution of new attacks and ever-increasing number of vulnerable hosts on the Internet, several DDoS attack detection, prevention or prediction techniques have been proposed. Some of these techniques have shortcomings such as high false positive rate, high computational time, low prediction precision and so on. In order to overcome these shortcomings, researches are being carried out to improve on the existing systems. This paper, which is one of such efforts to improve on the performance of existing DDoS attack prediction methods, presents a novel learning method based on Variational Bayesian (VB) algorithms to obtain an Hidden Markov Model (HMM) with optimized number of states in the HMMs and its model parameters for DDoS attack prediction. This method not only overcomes the shortcomings of the slow convergence speed of the HMM approach, but it also avoids the problem of overfitting the model structure by removing excess transition and emission processes. From the experiments with the DARPA 2000 intrusion specific datasets, this method is able to find the optimal topology in every case. The experiments show that the VB-HMM approach has a better average precision rate than the HMM trained by the Baum-Welch method. This shows that the VB-HMM method is better optimized than the HMM trained by the Baum-Welch method
PERFORMANCE EVALUATION OF 1 kW HORIZONTAL AXIS WIND TURBINE FOR RESIDENTIAL USE IN ABEOKUTA
Get PDFThe conventional energy sources are mainly use in Nigeria to generate electricity and yet, there is a critical challenge of electric power deficit. Therefore, design, modeling and simulation of 1 kW horizontal axis wind turbine as alternative power supply for residential use is considered. This paper presents the design, modeling and simulation of horizontal axis type wind turbine with power output of 1 kW at a wind speed of 4 m/s. Analysis of wind power capacity in W/m2 was done based on the obtained wind data using Weibull probability distribution function. The results showed that the average exploitable wind power density between 4 W/m2 and 14.97 W/m2 was realizable. The wind turbine blades were modeled using blade element momentum theory. The rotational speed of the blades was increased by using airfoil. Mathematical equations were used to determine the tip speed ratio, lift and drag forces and the power output. The MATLABTM AND SIMULINKTM scientific computer program was used to simulate the model of the wind turbine. The model with its required input parameters, pitch angle, rotational speed of the rotor, angle of attack, and wind speed were varied above and below its actual settings. The results showed that when the parameters were decreased, there was no power output and with the parameters values above the actual settings, the output power was increased to 2.5 kW at a wind speed of 8 m/s and generator speed of 620 rpm. The capacity is small and it is affordable for many household applications in Nigeria
DEVELOPMENT OF A MODIFIED CLONAL SELECTION ALGORITHM FOR FEATURE LEVEL FUSION OF MULTIBIOMETRIC SYSTEMS
Get PDFFeature level fusion is the combination of biometric information contained in the extracted features of biometric images. However, feature-balance maintenance and high computational complexity are one of the major problems encountered when fusion is done at feature level. Therefore, in this paper, a Modified Clonal Selection Algorithm (MCSA) which is characterized by feature-balance maintenance capability and low computational complexity was developed for feature level fusion of multibiometric systems.The standard Tournament Selection Method (TSM) was modified by performing tournaments among neighbours rather than by random selection to reduce the between-group selection pressure associated with the standard TSM. Clonal Selection algorithm was formulated by incorporating the Modified Tournament Selection Method (MTSM) into its selection phase. The modified algorithm could be employed for feature level fusion of multibiometric systems
MECHANICAL PROPERTIES OF THREE SELECTED TIMBER SPECIES IN ABEOKUTA, OGUN STATE, NIGERIA
Get PDFThis study was conducted to determine the physical and mechanical properties of some common Nigerian timber species in Abeokuta, southwest Nigeria.. The timber species considered are: Ayinre (Albizia coriaria), Aga (Musanga cecropioides) and Orin dudu (Anogeissus leiocarpus). The physical properties of the selected timber species including moisture content and density were determined in accordance with timber design codes {EN 13183-1 and EN 408}. Mechanical properties of the timber species were determined using both four and three point bending tests based on standards such as EN 408 and ASTM D193. Characteristic values of the material properties were determined in accordance with EN 384. Mechanical properties and density of the selected timber species were modified to the equivalent moisture content of 18% in accordance to the standard code for Timber design in Nigeria (NCP). The least values of the mechanical properties obtained from the two standards mentioned above were considered
Solutions of Second Order Nonlinear Singular Initial Value Problems by Modified Laplace Decomposition Method
Get PDFIn this paper, we presented a reliable modification of the Laplace Decomposition Method (LDM) for solving non linear singular second order initial value problems. The method is used to obtain the exact solutions of the nonlinear singular initial value problems. The validity of the method is verified by using nonlinear Lane-Emden type differential equations as an example to show the effectiveness of the method
ASSESSMENT OF SAWDUST AS PARTIAL REPLACEMENT FOR FINE AGGREGATE IN CONCRETE SLAB
No full textThe cost of construction activities is a major concern in developing countries, because of rise in construction materials. This was the reason for assessingpartial replacement of sand with sawdust as fine aggregate in concrete slab. Concrete slabs with dimension 800 × 300 × 75mm at varying percentage composition of sand with sawdust from 0 to 10% at 2.5% interval in the concrete were produced. The flexural strength test was carried out on each replacement at 7, 14, 21 and 28th dayrespectively. Ultimate strength was developed at the point of failure. The flexural strength developed at 28th day for 0, 2.5, 5.0, 7.5 and 10% were 6.8, 6.0, 5.4, 5.1 and 4.5 N/mm2respectively. The optimal replacement recommended was 2.5% and the least was 10%. The results indicated that concrete containing sawdust as partial replacement for sand can be used for concrete slab, thereby reducing cost of construction works
LIFE CYCLE ASSESSMENT OF WHEAT PRODUCTION AND PROCESSING SYSTEM
Get PDFWheat being the leading source of vegetable protein in the human diets has higher protein content than other major staple grains or cereals like rice or maize; therefore it was necessary to study the environmental impacts associated with its field production and industrial processing using the life cycle assessment tool. The functional unit selected for the study was 1kg of wheat, and emission from various inputs into the system was aggregated into a large inventory table. Four environmental impacts were considered namely; global warming, acidification, eutrophication and ozone layer depletion. It was discovered that global warming has the highest impact score which is closely followed by eutrophication; 4.7153E – 02 kg CO2 equivalent and 3.5907E– 04kg NO3- equivalent respectively, while ozone layer depletion has the lowest environmental impact score of 1.1889E – 07 kg R11 equivalent. High emission of CO2 gas from fossil fuel during field operations and processing of wheat was observed as the reason for the high impact score of global warming