Advances in Science and Technology Vol. 154

Abstract: This research was carried out to compare the performance of ANFO and Ammonium Nitrate on fragment size distribution by using the ANFO and AN as the column charge in blasting operations, measuring the fragmentation size after each blasting operation, characterizing the fumes evolving from the blasting operation in each case and compare the performance of the ANFO and AN. The densities of the rock deposit were derived as 2.638 g/m³ and 2.622 g/m³ for Block A and Block B respectively. The rebound hardness tests ranged from 47 to 61 for Block A and Block B from 48 to 54. The total explosive charge used for each of the blocks was 0.1 kg. The muckpile magnification ratio for Block A was 0.008 and Block B was 0.004. The fragmentation sizes for Block A range from 1.869 cm to 19.411 cm and Block B from 2.414 cm to 37.177 cm. The magnification ratio and fragment sizes show that Block A has better fragmentation than Block B. Ammonia gas was not present in the area of study before blasting but the fume emitted after first blasting with ANFO produced 0.08% of Ammonia gas and after the second blasting with AN 0.07% were produced. The oxygen level was reduced from 20.9% before blasting to 19.2% after the first blasting and 19.1% after the second blasting. It was deduced that blasting with ANFO generated more Ammonia gas than blasting with AN but the Oxygen level when ANFO is used was higher than when AN is used. Keywords: Blasting, density, explosive, fragmentation, magnification ratio

Abstract: The automotive industry faces a significant challenge in meeting the increasing demand for lightweight and eco-friendly vehicles with reduced energy consumption and lower air pollution. This challenge is driven by factors such as consumer preferences, strict government regulations, technological complexities, cost considerations and market acceptance. Aluminium metal matrix composites (AMMCs) are novel materials with high suitability to address this challenge. Currently, AMMCs used in the automotive industry are reinforced with conventional synthetic ceramic particulates and they have shown tremendous improvements over unreinforced alloys. These composites have wear resistance and strengths equivalent to that of cast iron but with about 67% less density. However, synthetic reinforcements are expensive, have limited availability, possess high abrasiveness, cause unwanted reactions, pose recycling difficulties and their production leads to the emission of greenhouse gases. It is now pertinent to consider the use of agricultural waste derivatives as possible substitutes for these conventional reinforcements. In this work, the various agricultural waste derivatives that have been used to reinforce Al matrixes were reviewed and the potentials of the resulting composites as promising candidates for lightweight automotive applications were assessed. It was concluded that agricultural waste derivatives contained hard ceramics particles which improved the mechanical, tribological, thermal and corrosion properties of AMMCs, making agro-waste derivatives reinforced aluminium metal matrix composites promising for the production of novel lightweight automotive components.

Abstract: Despite several advantages of hydroxyapatite, the main shortcoming is its low mechanical properties. The aim of the research study is the production and characterization of Rice Husk Ash reinforced hydroxyapatite ceramic composite for bone repair. The effect of Rice Husk Ash content and sintering temperature on the wear rate, physical and mechanical properties of the fabricated composite was investigated. The porosities obtained for the samples range from 39±0.1 to 56.53±0.14%. The porosity obtained in this study falls within the range of 40 and 90% which makes it suitable for osteo-integration. The trend from the mechanical properties shows that the addition of the rice husk ash significantly improves the measurement since it serves as a barrier to the propagation of cracks and consequently serves as an additional toughening mechanism. The wear rates obtained for the samples are 0.036, 0006, 0.0016, 0.009 for 0, 0.5, 1, and 1.5 wt.%RHA respectively. This shows that the wear rate of the samples reduces drastically with the addition of the rice husk.

Abstract: Municipal solid waste management continues to be an enormous challenge for developing countries such as Nigeria. With a rapidly increasing population and change in consumption choices in urban cities in Nigeria, the need to cater for and properly manage the increased volume and more diversified waste generated becomes an urgent issue for consideration. Storage and Collection of generated waste make up the crucial elements of waste management systems in any city. Sadly, though, just about a quarter of waste generated in Nigeria is collected. This paper compiles relevant information from recent studies made by researchers and authors on waste management systems in Nigeria to review the current state of the waste storage and waste collection systems in major cities in Nigeria using Lagos and Abuja as case studies. This study also summarizes the methods majorly used for the storage and collection of waste in Nigeria, making recommendations as and when necessary.

Abstract: The continuous degradation of available water resources coupled with the high cost of conventional water treatment has led to alternative, sustainable and cost-effective methods of treating wastewater. This study investigated the efficiency of Carica papaya seeds in the coagulation of moderately turbid water while determining the optimum treatment dosage and evaluating the treatment efficiencies compared to the use of conventional Aluminum sulphate (alum). Moderately turbid wastewater was obtained from Ala River tributary in Akure, Ondo State, Nigeria. The coagulation experiments were carried out at room temperature in a jar test. The experiments were carried out using 0.2 g/L, 0.4 g/L, 0.6 g/L. 0.8 g/L, 1.0 g/L, 1.2 g/L and 1.4 g/L doses of Carica papaya seed powder. An alum dose of 1 g/L was used as a control dose. The pH, turbidity, total hardness, total dissolved solids (TDS), and biochemical oxygen demand (BOD) of the raw water and treated water samples were analyzed. The pH of the raw water sample was 7.8; after treatment, the pH ranged from 7.7 at 0.2 g/L to 8.0 at 1.0 g/L treatment dose with Carica papaya seed powder. The optimum dose for turbidity removal was found to be 0.8 mg/L which amounted to 74.5% turbidity removal efficiency compared to 93.1% for alum. The hardness of the raw wastewater sample was 102 mg/L. After treatment, the hardness reduced from 99.4 mg/L at 0.2 g/L treatment to 77.6 mg/L at an optimum dose of 0.8 g/L. The TDS reduced from 564 mg/L at 0.2 g/L treatment with Carica papaya seed powder to 388 mg/L at an optimum dose of 0.8 mg/L amounting to a 78.9 % contaminant removal. The percentage BOD removal at 0.8 g/L of Carica papaya treatment was 86.3% while at 1.0 g/l, it was 100%. This study demonstrated that Carica papaya seeds is useful for the removal of contaminants from moderately turbid wastewater at varying percentages under different doses of papaya seeds.

Abstract: The unkempt state of many ceiling fans in offices, homes and industries due to poor maintenance in term of cleaning and the wastage of energy as a result of carelessness in appliance usage inform the design of a ceiling fan with autonomous capability. The design of the ceiling fan was done using appropriate design equations and Solidworks CAD software. Different concepts were conceived and the best concept was determined using one of the Multi – Criteria decision Tools named Pugh Matrix Method. After which, simulation was done using ANSYS and Proteus 8.1 design suite to test functionality of the design. The outcome shows that at no load in the room, the ceiling fan switches off automatically and also when occupants are in the room with an increase in temperature above ambient temperature (25 °C), the ceiling fan switches on. The simulation results analysis of stress, strain, shear force, deflection, factor of safety and bending moment on the embedded cleaner gave 112.717 MPa, 0.007496, 5 N, 60.28 mm, 1.8346 and 0.8965 Nm respectively. Furthermore, the result revealed that the autonomous capability of the cleaning mechanism gave an efficiency of 85%. The cost to implement this innovation is estimated at twenty five dollar.

Abstract: Visible light communication has advantages over acoustic and radio wave transmissions in free-space and underwater. The optical transmitters are usually light emitting diodes or laser diodes, and the optical receivers are usually photodiodes or its variants. Solar panels are used for solar energy harvesting to electricity, but the panels are also available in small sizes, and hence, are finding increasing use in optical communications due to larger aperture compared to photodiodes. This work investigated by experiments the characteristics of solar panels as receivers in visible light communication (VLC). In the work, four solar panels of different physical sizes were selected for experiments and measurement. Two characteristics important to communication were investigated. First is the internal resistance at different low illumination levels of white light. Second is response to sinusoidally varying intensity of white light at varying frequencies. For the first study, two of the four panels were investigated; and for the second study, the four solar panels were investigated. An array of seven white LEDs was used as the light source. Also, underwater data communication in saline water was performed for one of the solar panels, and a photodiode in comparison. Results showed that under steady illumination, the internal resistance is both illumination level-dependent and surface area-dependent. It decreases with increase in illumination level, and surface area. Also, the rate of decrease of the internal resistance with illumination increases with surface area. For the frequency response, the cut-off frequency of the solar panel is surface area-dependent, and load-dependent. It decreases with increase in surface area, and increases with decrease in load resistance values (increased loading). For data communication, the maximum data rate obtainable with the solar panel is less to that of the photodiode. The frequency response is important in considering the bandwidth of the solar panels, which also varies with the load, while the internal resistance is important in maximum power point tracking and impedance matching with front end circuits in optical communication receivers.

Abstract: This paper presents performance-based study of the Nigerian Transmission Grid (NTG), having about 27 power stations, 50 transmission (330/132kV) stations and 150 bulk load centers (132/33kV). Power stations and transmission grid are designed to operate at a level close to installed capacities, to achieve high efficiency. However, due to some technical limitations and maintenance factors, not all the elements may be available at all operating times. Therefore, the available generations may not equal the installed capacity; also, the load demand (consumed) on the grid may not equal the installed transmission capacities. This study evaluates the capacity of the transmission grid considering the installed and available generation capacity and three components of transmission load: actual load demand (LD), transmission wheeling capacity (TWC) and transmission load capacity (TLC). Obtained system data were used to create virtual simulator for the transmission grid, using Power System Analysis software (NEPLAN), which uses Newton Raphson Algorithm. The results established that the power generation on the grid must be maintained at the level of installed capacity to deliver the TWC and TLC load component to mitigate the practice of rotational power transmission and distributions currently being adopted in electricity transmission and distribution in Nigeria. It was established that the transmission capacity of the current transmission network is capable of accommodating and delivering power more than the current installed generation capacity. It is recommended that efforts be geared towards improving the generation capability of the grid for efficient power transmission and distribution. Keywords: grid capacity, transmission grid, load, system collapse, voltage stability

Abstract: To allow for optimum operation of the secondary system of lines, it is essential that the performance of the system be evaluated. Optimal functioning refers to the most desirable and favorable system of operation such as: improved system reliability, adequate and satisfactory electric potential profile, no imbalances in the phases of electric potential and electric charge, complete absence of overloading of electrical conductor used and energy converting devices and approved and allowable loss. This investigative research assesses the efficiency of the distribution system of lines resulting from electric potential deviation, electric potential imbalances, electric potential losses and electric potential fluctuation through the use of MATLAB/Powerlib tools. This research offers most desirable and favourable assessment of Typical, Sub-Saharan Africa secondary unbalanced system of lines. The system of lines was designed with approved and accepted system of line parameters for secondary Sub-Saharan Africa typical system of lines through the use of MATLAB/Powerlib software. The desire outcome got from the MATLAB model with the 500 meters distance for unbalanced system of lines is within permitted actual electric potential limit of minus five per cent for electric potential loss, plus and minus five per cent for electric potential deviation, electric potential imbalances is less than 2 per cent, and the electric potential profile at the end users is within 0.95 and 1.05 per-unit.

Abstract: Static security is the property of power system to maintain steady or stable operating state when contingencies such as line outages or component failures occur to avoid economic and technical losses. This study assessed the static security of the Nigerian 330 kV, 30-bus electric power transmission grid using a contingency approach. The steady state performance of the power system was modelled using Newton-Raphson based load flow equations and simulated in ETAP software environment. Bus voltage and line loading violations were determined by observing the voltage profile and line flows compliance with the voltage statutory limit of 0.95 to 1.05 p.u. and 80% loading of the thermal (MVA) limit respectively. N-1 contingency evaluation was conducted on fifty lines of the considered network. Performance index (PI) of the outage lines was determined and used to rank each of the contingency cases. Load flow analysis revealed that New – Haven, Onitsha, Gombe, Jos, Kano and Calabar with voltage magnitudes of 0.9003, 0.9468, 0.6608, 0.8141, 0.8138 and 0.9319 p.u. respectively violated the voltage statutory limit while Okapi-Calabar and Alaoji-Calabar with loading of 101.6 and 84.19 % respectively exceeded the recommended 80% loading of the MVA limit. The system total active line loss was 218.08 MW. Contingency analysis results ranked Benin-Onitsha and Ikeja West-Aiyede having the PI of 80.73 and 3.56 as the most and least critical lines respectively. This study established the suitability of contingency method for the assessment of security of a large-scale network such as the Nigerian electricity grid.