Arid Zone Journal of Engineering, Technology and Environment (AZOJETE)
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Structural Evaluation of Conventional and Modified Flexible Pavement Performance
Get PDFExperimental studies indicate that using rubber particles (RP) as additives improves hot mix asphalt (HMA) engineering properties when used as a road surface layer. Two critical strains are identified with asphalt pavement: horizontal tensile strain beneath the AC layer and vertical compressive strain on top of the subgrade. However, these strains are difficult to be predicted by experimental simulations. This research aims to conduct a comparative structural performance evaluation of conventional and modified asphalt pavement cross-sections with a particular reference to compute pavement responses (stress, strain, deflection, and stiffness) by utilizing Kenlayer computer code. Each cross-section is modelled as an elastic multilayer system consisting of five (5) layers with assigned material properties. The pavement compositions illustrate a typical highway pavement structure. The elastic modulus for both HMA materials was obtained at the average design temperature of 25˚C to reflect tropical and subtropical regions. The standard tandem axle load that causes damage to the pavement having a contact pressure of 673 kPa (0.673 MPa) with a set of dual tires center to center spacing of 33.75 cm was considered. The similarities and differences between the two pavement cross-sections concerning performance responses are compared. The analysis revealed that for both conventional and modified HMA cross-sections, the horizontal tensile strains at the bottom of the surface and binder layers are (2.62E-06 & -172E-04) and (-2.04E-05 & -2.14E-04) µε; at the same time, the vertical compressive strains on top of the subgrade are (1.57E-04) and (1.69E-04) µε. And finally, the computed surface layer stiffnesses are (833.51 kN/cm) and (734.89 kN/cm). It is appropriate to say that the modified HMA significantly decreases the surface layer’s stiffness; as such, it eventually prolongs the rapid encroachment of fatigue cracking and rutting deformation.
 
Applications of Various Types of Circuit Breakers in Electrical Power Systems: A Review
Get PDFThis paper presents a review on the applications of various types of circuit breakers (CB) used in electric power transmission and distribution. Circuit breakers are majorly classified under direct current (DC) or alternating current (AC) system. It shows that the most suitable way of classifying circuit breakers is on the level of voltage rating which is broadly grouped under direct current (DC) or alternating current (AC) circuit breakers. However, reviewed literatures did not clearly distinguish the respective applications of the different types of circuit breakers as applied to DC and AC power network. The DC circuit breakers which comprises of mechanical, solid-state and hybrid breakers are mostly applied in domestic and industrial applications that employ the use of direct current (DC) especially in high voltage direct current (HVDC) network system for the protection of electrical devices. AC circuit breakers are grouped in high voltage and low voltage forms. The low voltage CB comprises of miniature and molded case circuit breakers used majorly in domestic and commercial installations. The high voltage circuit breakers are further subdivided into oil and oil-less forms. The oil-less CB is made up air, vacuum and sulphur hexafluoride (SF6) circuit breakers. These high voltage circuit breakers are majorly applied in high voltage and extra high voltage transmission systems for protection of power system equipment and electrical machines
Residential exposure of electromagnetic fields radiated from mobile base stations and broadcast transmitters
Get PDFThis paper presents the cellular base station electromagnetic radiation and its effects on human body. Due to technological advancement, human life is subjected to high level of electromagnetic emission. The effect of electromagnetic radiation (EMR) is recognized from health risk associated with exposure to it. The research work was performed in two Communication companies, namely COMPA and COMPB located in Owerri, Imo State, in two geographical areas of Onitsha – Owerri Road and Owerri Municipal. The study was conducted to ascertain power density measurement using SureCall signal meter in 72 houses within a distance of 200 - 2500 meters from the base stations. Results obtained revealed that the average cumulative power density at different distances of 200m, 500m, 800m, 1200m, 1700m, and 2500m were 1.54005627200µW/m2, 0.319382647200µW/m2, 0.171062647200µW/m2, 0.139667752800µW/m2, 0.028675447200µW/m2, and 0.001429063200µW/m2, respectively. These results were compared with International Standard and World Health Organization (WHO) allowable limits. In conclusion, it was observed that the power density varied with distance from tower and is highest at the shortest distance. Power density also varied from place to place depending on the infrastructure obstruction, like buildings or internal obstructions
Analysis of the Seasonal Variation in Turbidity Index in Sudan and Fresh Water Swamp Vegetation Zones, Nigeria
Get PDFThis study evaluates the seasonal turbidity index of two vegetation zones in Nigerian which are Sudan and Fresh water swamp. Thirty years (1981 – 2010) meteorological data of temperature, relative humidity and solar radiation were obtained from the archives of the Nigerian Meteorological agency (NIMET). Annual and monthly analysis of the turbidity coefficients were mainly based on the Linke and Angstrom methods, due to absence of radiosonde data. The results show that the monthly mean values of the clear-sky global radiation lies between 19.34 MJ/m2day to 24.44 MJ/m2day (for Sudan vegetation) and 15.54 MJ/m2day to 20.28 MJ/m2day (Fresh water swamp). Meanwhile, the monthly percentages of clearness index above 0.6 were estimated as 75% and 33.3, and for the water vapour content exceeding 3 cm to be 58.3% and 100%, for the Sudan and Fresh swamp vegetation, respectively. These values contribute significantly to the reduction of direct radiant energy. The results obtained for the seasonal index for Linke and Angstrom coefficients show that for the wet season, the index exceeded the dry value by 25.99% and 23.66% for Sudan and Fresh swamp vegetation, respectively. By implication, the Fresh water Swamp is laden with more aerosols than Sudan zone. Additionally, the R2 obtained for the relationship between Angstrom and Linke is 0.999 for both locations. Hence, the study provides an insight into the contribution of aerosol in the attenuation of solar radiation over the atmosphere for these locations
Nutritional and Quality Assessment of some Irrigated Wheat Genotypes in Nigeria
Get PDFThe aim of this study is to evaluate the nutritional and end-use qualities of some advanced irrigated Nigerian grown wheat genotypes which was developed and produced by Lake Chad Research Institute, Maiduguri, Borno State of Nigeria. Standard methods were used to determine the physical, milling, proximate, baking, sensory, functional, rheological and textural qualities of the Nigerian grown wheat. The result showed that grain physical characteristics of the eleven irrigated wheat genotypes were statistically significant. Flour extraction differed significantly from 66.1-79.6% in the irrigated wheat genotypes. Three irrigated genotypes namely, Florkwa-2, Soonot 5, and Hubara-3 had the highest flour extraction rate with flour yield above 75%. Proximate flour quality indicated significantly higher protein content in Hubara (15.2%), Pastor-2 (15.8%), Kauz (16.2%), Soonot-5 (15.8%), while Katila-17 had higher carbohydrate (73.2 %) than Hubara-1. The results for dough and bread functional and textural qualities further showed that Attila-7, Katilla17, Angi-2 and Soonot-5 were superior to the other genotypes, and comparable to the standard imported flour. However, bread sensory evaluation gave the standard flour higher score rating. Therefore, the nutritional and end use quality indicated that Nigerian grown wheat had properties suitable for bread production. The wheat genotypes namely Soonot -5 and Attila-7, among the other irrigated genotypes used in this study, were rated higher in bread baking quality and were even comparable to the standard imported flour which indicated that Nigerian grown wheat can be used to produce bread
 
Development of a windmill for pumping water using positive displacement pump
Get PDFThe abundant renewable energy sources have not been harnessed for electricity and other uses to date. Wind speed is high in the Northern part of Nigeria and therefore require utilization so as to reduce the use of harmful non-renewable energy sources. In this work wind energy was used to drive a windmills that provide mechanical energy directly for a borehole with a positive displacement pump with a 2.5ft stroke. The design analysis of the wind mill was carried out numerically based on the wind data collected. The proposed design were fabricated using designed dimensions. The rotary motion of the shaft were converted to a linear motion using slider-crank mechanism. The designed horizontal axis windmill has 3 blades has three blades driving the shaft. Also the kinematic modelling of the mechanism was carried out. The assembled windmill was tested and was found to have an operated efficiency of 58.2%.
 
Propagation Loss Determination of GSM Signal Strength in Selected Buildings in Ilorin, Nigeria
Get PDFGSM signal building penetration loss is a problem often encountered by subscribers inside a building. As a result of building penetration loss, poor reception and signal outages often occur in many indoor locations and this accounts for increased attenuation of received signal strength of a cellular network signal when a subscriber with a mobile phone moves from outdoor to indoor. The study assessed the GSM signal penetration loss in thatched, wooden, block, mud and zinc buildings. Three network providers named A, B and C was used for the experiment. A low budget but very effective equipment (Two Tecno Pouvoir 3 plus Android phone) was used as the measurement tool. It was loaded with Network Signal Info application developed by KAIBITS Software GmbH installed software and positioned inside and outside the building to record indoor and outdoor GSM signal strength respectively for the three service providers in Ilorin, Nigeria. The results were then analyzed in order to determine and compare the path loss introduced by each of the selected buildings. This process was repeated for all the selected buildings, and the measurement was carried out for 6 months. The findings revealed that the outdoor signal strength was higher than the indoor signal strength for all the selected buildings; it also revealed that penetration loss is likely to be a function of the material used in the construction of the buildings. Zinc building has the highest penetration loss of 12.0dBm and thatched building has the least penetration loss of 2.6dBm. Information from this research will assist in selection of building materials for good indoor cellular network signal reception. It will also assist cellular network service providers in the link budget preparation for environments where similar building materials are used.
 
Development and Deployment of Quadcopter in Silos’ Inspection and Surveillance
Get PDFEfficient and routine inspection/surveillance of agricultural installations is a panacea that guarantees structural integrity and healthy storage of grains. Conventional methods of silo inspection are tedious, time-consuming, costly, disruptive and with attendant safety concerns. A quad copter comprising four Electronic Speed Controller (ESC), four Brushless DC motors, a motion camera, a flight controller unit, a battery and an off board remote controller was designed, developed and evaluated for silos’ facility inspections. The system is powered by 11.4V LiPo (Lithium polymer) fitted on-board of the quad copter, a digital camera and a 12V remote controller for off-board control (yaw, pitch and roll), with an entire system weight of 3.62kg. Apt deployment of such unmanned aerial vehicle in routine facility integrity inspection eliminated the high risk and loss of man hour associated with contemporary techniques. The result of its performance test indicated that the system has maximum attainable speed of 10km/h and maximum height/range of 150 m for over all 10 minutes of flight time. Also, the threshold speed for each rotor was found to be 1030 rpm and an average speed of 0.5km/h needed during inspection of silos to avoid blurred images from the camera was achieved. Comparative analysis of the design with the conventional method revealed that the developed quad copter was cost and time effective, convenient, risk free thus recommended for full scale deployment for inspection/surveillance in silo installations
Production and Characterization of Biodiesel from Hybrid Feedstock of Jatropha curcas and Thevetia peruviana Seeds Oil
Get PDFThis study elucidates one possible alternative to first generation feedstock used for biodiesel synthesis. The various conventional feedstock for biodiesel production have the conflict of competition as food sources which poses serious food security risks. Jatropha curcas and yellow oleander seed oils were subjected to in-situ hybridization process at different percentage blend compositions tagged: Y90J10, Y80J20, Y70J30, Y60J40 and Y50J50 before trans esterified to biodiesel. Biodiesel yields were found to be as high as 90.0, 86.1, 90.7, 92.2 and 88.2% for the hybrid blends Y50J50, Y90J10, Y80J20, Y70J30 and Y60J40 respectively. The optimal reaction temperature was 60°C, reaction time of 60 minutes, using 1% (w/w) KOH catalyst. Characterization of all synthesized biodiesel samples indicates fuel properties that are within the stipulated ASTM limits for fuel-grade biodiesels, except that high cloud points were observed in Y100 and J100. The least cloud point was observed for biodiesel from hybrid oil blend Y50J50. The FTIR spectra of the fatty acid methyl esters of both oils and of their various blends confirms the presence of the major functional groups characteristics of bio-based diesel fuel.
 
Modelling the Safety Level of the Construction Industry in Southwestern Nigeria
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The number of accidents in the construction industry in Nigeria is very high. It is rare to disclose safety performance metrics required to draw government attention to these incidents. This research aims to develop a predictive safety analytical model for the construction industry's safety assessment. The activities of safety standards in the Nigerian construction industry and improvement programs expected to be introduced in the construction industry have been researched to recognize the risks of construction accidents. The building injury risks found were modelled as predictor variables while the response variable was the level of safety using multiple regression analysis. Spearman's Correlation Analysis identified predictor variables that correlate significantly at p˃0.05 to the safety level, while predictor variables with low correlations have been excluded. The safety level was calculated on a linguistic scale of 5 points. The predictive ability of the model was verified at a 5 percent significance range by the coefficient of determination (R2) and the t-test. Under Law and Regulation, Practices, Personal Factors and Encouragement, fifteen task-related construction accident risks were identified and listed. The developed multilinear regression model has an 84.8% R2 rating. A 92.1% correlation between the predicted values and the human-interpreted safety-level values was revealed by the model implementation. The study also shows that personal variables should be given the highest degree of consideration by site engineers. The t-test showed no substantial difference between the values predicted and the values perceived by the level of human protection. Due to the feasibility of the study, the constructed model will serve as a valuable instrument for monitoring the safety level of Nigeria's construction sites. It is recommended that the model be used by site Engineers and Safety personnel from Federal and State Ministries.