Master of Science (M.Sc.) Theses and Dissertations

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    Open Access
    A comparison of different formulations of offset-free nonlinear model predictive control
    (Department of Chemical Engineering, Obafemi Awolowo University, 2023) AYOADE, Micheal Temitope
    This study developed the simulation model of the different algorithms for offset-free nonlinear model predictive control (NMPC), applied the developed simulation model on selected benchmarked processes and on an experimental process rig. The study then made comparison among the different formulations. These were with a view to comparing the various methods of designing offset-free nonlinear model predictive control.
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    Open Access
    An Appraisal of GSM Telecommunications services delivery in Lagos and Oyo state of Nigeria.
    (Department of Technology Management, Faculty of Technology, Obafemi Awolowo University, 2008) Abdul-hammed, Taofeek Adekune
    The study appraised the quality, volume, and capacity of the telecommunication facilities of the GSM service providers in Lagos and Oyo States of Nigeria. This was to develop strategies for improved service delivery in the industry.
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    Comparative studies on the effect of dying methods on quality properties of yellow fleshed sweet potato flour
    (Department of Food Science and Technolgy, Faculty of Technology, Obafemi Awolowo Universty, Ile Ife, 2022) BADIORA Aishat Olanike
    This study optimized the processing parameters of yellow-fleshed sweet potato flour (YFSP) using drum drier; compared the quality properties (proximate composition; mineral content, physicochemical, pasting, functional and rehydration properties) of flour produced from sun; oven and drum drier and determined the sensory properties of the reconstituted sweet potato flour. These were with a view to producing acceptable YFSP flour using different drying procedures. The tubers were weighed, sorted, washed, peeled, diced, wet milled into slurry for drum dried samples while oven and sun-dried samples were milled, sifted, weighed and packaged. The pretreatments and drying conditions were blanching at 85 ºC for 3mins 30secs, steam cooking at 120 °C for 2mins, sun drying (3 – 4 days at 27 ± 2 °C), oven drying (70 °C for 8 hours) and drum drying at 150 ºC, 10 rpm, 100 ml (84.05%). The proximate composition, mineral content, physicochemical, pasting, functional, rehydration and sensory evaluation of reconstituted YFSP dough were determined using standard methods. Appropriate descriptive and inferential statistics were used to analyze the data. The proximate composition of the samples showed that oven drying method decreased the moisture content of untreated and treated YFSP flour samples (4.88 – 5.31%) and the ash content (1.50 – 1.62%). All the drying methods increased the carbohydrate contents (73.15 – 81.33%) of YFSP flour samples. Sulphiting decreased the pH of the treated samples (5.58 - 5.90) while untreated sun and drum dried samples had increased pH (6.12 - 6.47). Drum drying method increased the mean particle size of drum dried samples compared to other methods. Untreated and treated samples had lower water absorption capacity (WAC) of 106.5 – 126% and oil absorption capacity (OAC) of 83.5 – 106%. Pretreatment reduced the WAC and OAC of YFSP flour samples. Drum drying method increased the WAC (531%) and OAC (168%) of the drum dried flour samples while it decreased the gelatinization temperature (78.5 ºC) and dispersibility (35%) of the samples. Swelling and rehydration capacities of untreated and treated samples increased as the drying temperatures increased from 80 and 90 ºC. The results showed that drying methods had effect on the pasting profile of the flour samples with the drum dried samples having the lowest values compared to other samples. The mineral contents: calcium (0.47 – 1.37 mg/100 g) and potassium (0.37 – 0.47 mg/100 g) of all the flour samples decreased during pretreatment and processing. Blanched sun-dried samples were the best overall flour based on the sensory properties (colour, taste, texture, mouthfeel and overall acceptability) while drum dried samples had the best functional properties based on water and oil absorption, swelling and rehydration capacity at 28 ± 2 ºC, 60 ºC and 70 ºC. The reconstituted dough from sun and oven drying methods were acceptable by the panelists, except for the drum dried dough. However, dough of steam cooked and sun-dried samples were ranked best. The study concluded that acceptable yellow-fleshed sweet potato flour could be produced from yellow fleshed sweet potato tubers by employing either of sun drying, oven drying or drum drying methods.
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    Open Access
    Developement of a Scenario Based Emergency Response Model for Flooding in Nigeria
    (The Department of Computer Science and Engeneering, Faculty of Technology, Obafemi Awolowo University., 2022) AKHAINE, Victor Emuata
    This Study characterized factors and collected data responsible for flooding, formulated a scenario-based model using the characterized factors and data collected, and simulated and evaluated a model. This was with a view to aiding the planning phase of response agencies by reducing uncertainties through synthetic scenarios. Data based on factors responsible for flooding, were elicited by interviewing experts at the Nigerian Hydrological Service Agency (NHSA), combining systems theory with Delphi method and Cross impact analysis the scenario based model was developed and simulated in python programing language. The causal factors elicited in the course of the interview were categorized into Initial Conditions, Dynamic Events and Outcome Events. In total there were 24 events. The response from the experts were then used to create a probability scale to rank relationships between the events which served as input to the model to generate 6 scenarios, these scenarios were then displayed in graphs. The model was evaluated for accuracy, precision, internal consistency and root mean squared error and verified by comparing the output against recurring events from historical analysis. The results showed that the model had a precision and accuracy of 100% which represents the predictive capability and RMSE of 5.44. the dataset gotten from the experts had an internal consistency of 0.53, 0.7381, and 0.82 based on 3 set of questions in the Delphi questionnaire. Out of the 6 scenarios, flooding had severe impact in scenarios 0, 1,3, and 5 which showed high probability of human casualties, huge economic losses and social unrest. Scenario 4 however showed a reduction of the probability of human casualties and social unrest with the exception of economic losses. In order to further verify the scenarios generated by the model, all the recurring events in the study area were equated to a 100% and then compared with the average accuracy of the scenarios generated by the developed model which was 57.50%. xi The study concluded that the model results formed the basis to develop a dashboard to identify future events that are pivotal in disaster response, and because of this, proactive measures could be taken by the appropriate agencies to respond towards mitigating flooding
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    Open Access
    Development and characterization of banana - fibre reinforced polymar composities.
    (Department of Chemical Engineering, Faculty of Technology, Obafemi Awolowo University., 2022) ILESANMI Olusola Joshua
    This study optimized a production process for banana-fibre composite suitable for engineering application, characterized the banana-fibre composites and established the influence of fibre loading and fibre length on the mechanical properties of the composites. This was with a view to developing a new class of environment-friendly natural-fibre reinforced composites suitable for engineering applications. Banana pseudo stem was collected from a local source from which banana fibres were extracted. Postconsumer PET bottles were obtained from local sources and shredded, washed and oven-dried at 110 oC for 2 hours. The shredded PET bottles were subjected to de-polymerization process via glycolysis in the presence of NaOH as a catalyst. Central composite design was used to generate 26 experimental runs for each mechanical property to be investigated. Fibre length (mm) and fibre content (%) were the two numeric factors considered while alkaline treatment was the categoric factor considered. Hand lay-up technique was used to fabricate the composites, ensuring a horizontal fiber alignment and a unidirectional fiber orientation for all the composites prepared. The polymer composites were left to cure for 24 hours at room temperature after which they were characterized for flexural, tensile and impact strengths. Modelling and optimization of the mechanical properties were carried out using Response surface methodology (RSM). The data obtained for the mechanical properties were fitted as second order equations. Analysis of variance (ANOVA), residual analysis, response surface plots and diagnostic plots were used to evaluate the validity of the models.The results showed that fibre length and fibre content had a significant impact on the flexural strength, tensile strength and impact strength of banana-fibre reinforced polymer composites. Quadratic models were developed for each of the mechanical tests and they were found to provide a good fit with experimental data. There was an increase in the flexural strength of the banana-fibre reinforced polymer composites as the fibre length increased up to 70 mm and as the fibre content increased up to 40%. However, flexural strength decreased as the fibre length further increased up to 80 mm and as the fibre content further increased up to 50%. Polymer composite with 70 mm fibre length and 40% treated fibre content gave the maximum flexural strength of about 3.6 MPa. There was an increase in the tensile and impact strengths of the banana-fibre reinforced polymer composites as the fibre length increased up to 50 mm and as the fibre content increased up to 40%. However, as the fibre length further increased up to 60 mm and as the fibre content further increased up to 50%, the tensile and impact strengths decreased. Polymer composite with 50 mm fibre length and 40% fibre content gave the maximum tensile strength of about 0.765 MPa and maximum impact strength of 9.99 J. The findings of this study showed that development and characterization of banana-fibre reinforced polymer composite could be achieved. Also, varying the fibre length and fibre content of natural-fibre reinforced polymer composites would improve their mechanical properties.
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    Development of a Drug Recommender System
    (The Department of Computer Science and Engineering, Faculty of Technology, Obafeim Awolowo University., 2024) EGBI, Alilu Grace
    This study elicited and analysed data on patients, drugs and disease. The study then designed a drug recommender model, implemented the model and tested the performance of the system. These were with a view to developing a drug recommender system that recommends appropriate drug(s) for the treatment of an ailment. Patients’ data were elicited from Medical Information Mart for Intensive Care – IV (MIMIC-IV), a deidentified clinical data of patient admitted in ICU at Beth Isreal Deaconess Medical Center (BIDMC). Drugs data were elicited from Drugs.com. Disease treatment knowledge were elicited from the guidelines on the treatment of Peptic Ulcer Disease (PUD) provided by the Japanese Association of Gastroenterologists. These data acquired were analysed using various functions in the Pandas library. The model for the recommender system was designed based on the Hybrid recommendation approach by combining clustering algorithm, Collaborative filtering approach (CF) and Knowledge-Based filtering approach (KBF). The factors that were considered for recommending appropriate drugs were age of patient, gender of patient, body weight, allergies and drug interactions. The model designed was implemented using the Python Programming Language version 3.6.3 with Flask framework for web development and Visual Studio Code as the Integrated Development Environment (IDE). And the performance of the system was evaluated using Precision, Recall, and Root Mean Squared Error (RMSE). The evaluation was carried out in two phases; Firstly, the CF component was evaluated by splitting the dataset from MIMIV-IV into 70% (60,018) train set and 30% (25,722) test set. Secondly, the KBF component was evaluated using 30 different cases. The evaluation for this was computed manually by comparing the recommendation results from the system with that of an expert. For the CF aspect of the DRS, the system had a precision score of 85.48%, a recall score of 85.58% and a RMSE score of 0.74. The precision result shows that the system has an 85.48% bability in making relevant recommendations. The recall score shows that the system has an 85.58% ability in recommending relevant drugs from all available relevant drugs. The RMSE score of 0.74 shows that the recommended drugs are far from the actual drugs prescribed. For the KBF aspect of the DRS, the system achieved a Precision of 77%, a recall of 83% and a RMSE of 0.24. The system’s Precision and Recall scores were lower when the KBF was added. This study concluded that the addition of the KBF reduced the error rate between actual recommendations and predicted recommendations. So, the system had a high ability in recommending appropriate drugs for PUD.
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    Development of a microcontroller-based integration of renewable energy sources for implementation of a hybrid power supply system.
    (Department of Electronic and Electrical Enigneering, Faculty of Technology, Obafemi Awolowo University., 2023) SAMSON Joseph Bukola
    This study determined the appropriate size for each of the renewable energy sources (RES) to be integrated, developed a microcontroller-based system capable of coordinating and monitoring the energy output power flow of the sources, and simulated and evaluated the performances of the system. This was done with a view to providing a sustainable solution for electrification of areas not connected to main power grid. The wind speed, solar radiation and load demand data of the study site were obtained from Obafemi Awolowo University, Ile-Ife and then averaged into 1-hour intervals for different geographical seasons. The sequential quadratic programming (SQP) approach was used in the study to determine appropriate and economically viable sizes for the integrated energy systems. The SQP approach was used in the study to find optimal and cost-effective sizes for integrated energy systems that meet the specified requirements. Suitable mathematical models, and size optimization were obtained for the system’s components. Using MATLAB (version 2021a), a microcontroller algorithm for optimal power flow in a hybrid renewable energy source (HRES) was both developed and simulated. For the HRES cost analysis, the overall installation cost and cost per kW of each component were estimated, and three different optimal configurations for the site location were compared for techno-economic analysis. The results show that an off-grid energy system based on RES, with biogas backup, is feasible in the examined location. According to the simulation results, renewable energy (RE) contributes 51.4 % of total load demand in December during the academic period of the weekdays and 96.4 % of total load demand over the weekends of the same period in June. The energy contribution from RES from storage facilities ranged between 20.1 % and 44.0 % of total load demand. Among the three different configurations viz wind/PV/pumped-hydro/battery/biogas, PV/wind/battery, and wind/pumped- hydro/biogas, as examined in this work, wind/PV/pumped-hydro/battery/biogas is discovered to be the most cost-effective configuration with Net Present Cost and Levelised Cost of Energy of $3,085,675 and 0.027 $/kW respectively. The optimal and most cost-effective solution proposed configurations consist of 500 kW of PV system, 400 kW wind turbine. In conclusion, the study showed that implementing an off-grid HRES with sufficient storage, utilizing the pumped-hydro storage system, can provide a sustainable solution for electrification of once not connected to the grid.
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    Open Access
    Development of a microcontroller-based integration of renewable energy sources for the implementation of a hybrid power supply system
    (Department of Electronic and Electrical Engineering, Faculty of Technology, OAU., 2023) Samson, Joseph Bukola
    This study determined the appropriate size for each of the renewable energy sources (RES) to be integrated, developed a microcontroller-based system capable of coordinating and monitoring the energy output power flow of the sources, and simulated and evaluated the performances of the system. This was done with a view to providing a sustainable solution for electrification of areas not connected to main power grid.
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    Development of an automatic extraction model for Yoruba text.
    (Department of Computer Science, Faculty of Technology, Obafemi Awolowo University., 2023) Ademusire, Adebisi Joseph
    The research collected Yoruba textual data and annotated them. It formulated a machine learning model for Yoruba text and implemented the model. It also evaluated the implemented model. These were with a view to developing a machine learning model for automatic event extraction for Yoruba text. This research employed a multi-faceted approach to achieve its objectives: data were collected through manual methods, including the conversion of Yoruba folktales from print to digital format via typing and subsequent data cleansing. The preprocessing of data was conducted using the Python programming language. A machine learning model, comprising Bidirectional Long Short-Term Memory (Bi-LSTM) Network and Convolutional Neural Network (CNN) architectures was formulated with fine-tuning of hyper parameters tailored for Yoruba text. The model was implemented using Python, and its evaluation was based on the analysis of over 100 unique Yoruba folktale sentences using standard metrics, including accuracy, F-score, precision, and recall. The results were highly promising, with the Bi-LSTM model for trigger and entity identification achieving an accuracy of 87.00%, precision of 91.72%, recall of 68.54%, and F1 score of 76.67%, while the CNN model for event type classification yielded an accuracy of 47.55%, precision of 52.07%, recall of 49.90%, and F1 score of 48.22%. These findings demonstrate the effectiveness of the developed model, especially the Bi-LSTM component, in capturing event triggers within Yoruba texts. This research not only advances the field of NLP but also contributes to the preservation of Yoruba language and culture, providing a well labelled dataset for event extraction benchmarking in Yoruba language. The study concluded the potential for applying advanced natural language processing (NLP) techniques to linguistically diverse languages and underscores the importance of linguistic diversity in the globalized world. It sets the stage for future research in event extraction from underrepresented languages, paving the way for broader applications in information retrieval, story generation, and cultural preservation.
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    Development of an improved tractor-mounted kenaf (Hibiscus Cannabinus) Harvester
    (Department of Agriculture Engineering, Faculty of Technology ,Obafemi Awolowo University, Ile - Ife , Nigeria., 2022) Thomas Adebayo Ayorinde
    The study designed and fabricated an improved tractor-mounted device for kenaf harvesting; it evaluated the performance of the machine developed. It also developed mathematical models for the torque, power and energy for the machine; and validated the models developed. These were with a view to developing a kenaf harvesting technology which will improve kenaf production efficiency. The tractor mounted kenaf harvesting machine has a rotary drive mechanism, which was adopted from a forage harvester. A review of the physical and mechanical properties of kenaf stem was made to ensure the accuracy of the design calculation for shaft, chain drive and gear design. The cutting blades, spur gears, bevel gears was designed and fabricated based on the design calculations. Performance evaluation of the machine was carried out at the kenaf experimental field set up at the Obafemi Awolowo University Teaching and Research Farm. The evaluation of the machine was carried out from 10 to 16 weeks after planting, at 2 weeks interval. The factors considered in the evaluation include; crop maturity, crop varieties and forward speed of the machine. The machine parameters which are constant machine values peculiar to the machine performance evaluation include width of cut, speed of operation, height of cut. The performance indices were theoretical field capacity, field efficiency, effective field capacity and operational loses. The results obtained was analysed using 3-level factorial response surface methodology (RSM) of design expert software. A mathematical model was developed to detemine the cutting behaviour of the machine when modelled as a fixed uniform cantilever. An equation to predict the cutting torque, power and energy requirement of the machine during operation was obtained and validated. The effective field capacity was observed to decrease with increase in plant maturity and increase with increase in forward speed of the machine. The highest effective field capacity recorded was 2.13 ha/day with Ifeken 100 at crop maturity of 10 weeks after planting, and forward speed was 5 km/hr. The field efficiency of the machine was found to decrease with increase in crop maturity, and forward speed of the machine. The highest field efficiency was 97%, with Ifeken 100, crop maturity of 10 weeks after planting, and at forward speed of machine of 2 km/hr. The duration of operation was also observed to increase with increase in maturity, and decreased slightly with increase in forward speed of machine. The highest duration of operation recorded was close to 9 hours, obtained when the crop maturity was 16 weeks after planting, during the harvesting of Ifeken di 400 and forward speed of 2 km/hr. Operatiional losses was observed to be uniform as the crop maturity increased, highest during the harvesting of Ifeken 100 and increased with increasing forward speed of the machine. The least operational losses recorded was 6.9% recorded when the plant maturity was 16 weeks after planting, during the harvest of Cuba 108 and when the forward speed of machine was 2 km/hr. There was good agreement between the predicted and experimental values of the cutting torque, power and energy requirement of the machine. The study concluded that with the current level of performance obtained for the machine in the research, it has the potential for inclusion in kenaf production operation.
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    Investigation of groundwater seepages using geotechnical and ground penetrating radar techniques
    (Department of Civil Engineering, Falculty of Technology, Obafemi Awolwo University, Ile Ife, 2022) BOBOLA Damilola Gbadebo
    This study evaluated the geotechnical properties of the soil in the study area, determined the stratigraphy, zone of fractures (micro and macro) and cavities with ground penetrating radar, correlated results obtained from the ground penetrating radar investigation with the geotechnical tests of the soil and developed a basemap for the study area for exposition of fractures and cavities zones using information obtained from the geotechnical and ground penetrating radar investigations. These were with a view to determining the causes of groundwater seepages in the study area using geotechnical and ground penetrating radar techniques. Five trial pits, each 3.6m deep were dug in the study area and soil samples were collected at 3.6m from each pit. Sieve analysis, natural moisture content, specific gravity, Atterberg’s limits, compaction, shear strength, permeability, and consolidation laboratory tests were carried out on them to determine their geotechnical properties. The Ground Penetrating Radar (GPR) survey data were acquired using a Geophysical Survey System Incorporated Sirveyor-3000 (GSSI SIR-3000) equipment with a central antenna frequency of 100, 200 and 400 MHz along 10 traverse lines and the data were subjected to processing by the Radpro software. The properties of the soil samples were then statistically analysed and correlated using Microsoft Excel Software Package. The vertical and horizontal stresses acting close to the fractured zone were also analyzed. Critical fracture delineated by GPR was then subjected to further geophysical investigation using Puqi Water Trace Detector (PQWT) instrument and a basemap showing zones of fractures and micro-fractures was generated. Three types of soils were identified based on Unified Soil Classification System (USCS): Silty Sand (SM), Clayey Sand (SC) and Clay with low plasticity (CL), with plasticity for all the soil samples ranging from low to intermediate plasticity from the result of the geotechnical investigation. Also the shear strength of the soils were low to medium ranged with low permeability. The GPR radargrams delineated four subsurface layers. These include the top soil, weathered layer, partly weathered/fractured bedrock and the basement bedrock. Along traverses 1, 6, 8 and 10, geological structures (fractures and micro-fractures); which facilitated groundwater seepages were delineated from the radargrams. A critical fracture denoted as F1 with width of atleast 2 metres was delineated by GPR in traverse line 1 along with one other fracture (with width close to 1.2 metres) and one micro-fracture (few centimetres wide). Several other micro-fractures were also delineated in other traverse lines. Correlation of some of the geotechnical properties of the soil samples show that, soils in the study area substrata with lower percentage of fines, are more prone to groundwater seepage, as they are more permeable and have high shear strength. Analysis of vertical and horizontal stresses of the subsurface close to fracture F1 showed that the weathered and partially weathered layer in the substrata of the study area are more prone to easy flow of groundwater seepage due to high vertical and horizontal stresses. Furthermore, mapping of the critical fracture F1 with PQWT instrument gave a profile map that delineated five distinct layers with varying density up to a depth of 150 m. Also, another fracture of 3 m width was observed directly under the fracture F1 delineated by GPR starting at a depth of 125 m below the ground surface. This wide fracture serves as a conduit for movement of groundwater to the subsurface as the fracture cut across the other subsurface layers. The study concluded that the basement floor was constructed close to a fractured bedrock leading to the incessant seepage of groundwater into the structure’s basement
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    Investigation of Corrosion Behaviour of Heat Treated Standard Steels in Nigerian Rich Tar Sand.
    (Department of Materials Engineering, Faculty of Technology, Obafemi Awolowo University., 2023) OGUNDARE, Olurotimi Joseph
    This study determined the corrosion rates of as-received and heat-treated standard duplex stainless (UNS S32205) steel in tar sand processing environment, characterized microstructurally the corrosion coupons, and correlated the corrosion rates of the stainless steel with their respective microstructures. These were with a view to assessing the suitability of heat-treated standard duplex stainless steels as candidate materials for the hot water tar-sands pilot plant. The Nigerian-rich tar sand sourced from Ilubinrin town, near Agbabu in Ondo State was chiselled into bits of 6mm and 25 g of it was processed using 0.5 M sodium hydroxide (NaOH), which acted as the surfactant in the bitumen recovery. The as-received stainless samples were subjected to annealing, normalizing, and quenching (water and oil) heat treatments. A processing temperature of 90oC and processing time of 4 hours was employed. After immersion, the corrosion coupons were cleaned with non-bleaching scurry powder and wiped with acetone to remove grease. The corrosion rates were determined by gravimetric technique and the microstructural analyses of the degraded corrosion coupons were carried out using scanning electron microscope while the correlation of the respective microstructures of the corrosion coupons with their uniform corrosion rates was carried out using localized corrosion rates derived from surface profilometry of the coupons. The study showed that water-quenched samples exhibited improved general corrosion resistance with longer precipitation times, while oil-quenched sample with precipitation time of 2 hours showed the lowest general corrosion rate, followed by water-quenched sample with a precipitation time of 4 hours. Microstructural analysis provided insights into the degree of pitting, with the annealed sample showing the highest and the water-quenched sample with a precipitation time of 4 hours displaying the lowest degree of pitting. These variations were attributed to passivity and an imbalance between ferrite and austenite phases due to secondary precipitates. The correlation between uniform corrosion rates and microstructures revealed that the sample with a precipitation time of 4 hours, followed by water quenching, demonstrated the best corrosion resistance. These differences in localized corrosion rates were attributed to chromium and molybdenum depletion in the grain boundaries. This study concluded that the heat-treated standard stainless steels were suitable for the construction of hot water tar sand pilot plant.
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    Laboratory investigation of factors influencing toxic air emissions from applied paints in the indoor environment.
    (Department of Chemical Engineering, Faculty of Technology, Obafemi Awolowo University, Ile-Ife, Nigeria, 2024) Aremu, Aminat Damilola.
    This study characterized common commercial paints for air pollutants in the indoor environment, and determined emission factors of the identified air pollutants from applied paints. It also modeled emissions of the identified air pollutants and developed a control pathway for toxic air pollutants. These were with a view to determining air pollutants from applied paints in the indoor environment. Some common commercial paints from Nigeria market were selected and characterized using gas chromatography mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) analysis. Gaseous and particulates emissions associated with the selected paints were characterized by painting selected experimental chambers using method of spraying painting and air brushes. Experimental measurements of air pollutants associated with the use of the selected commercial paints in indoor environment was carried out using air monitoring equipment. Emission factors of air pollutants were determined using standard mathematical correlations from AP-42. Suitable Specific Models were used to model emissions of toxic air pollutants subject to variables [time (t), temperature (T), relative humidity (RH), total volatile organic compound (TVOC) and particulate matter (PM)]. The obtained concentrations of toxic air pollutants from combinations of the exposed paint and exposure period were compared with the national ambient air quality standards (NAAQs) to determine their level of compliance and also to propose the policy framework for control of paints used in indoor applications in Nigeria. The results of GC-MS and HPLC characterization confirms the presence of VOCs and aromatic hydrocarbons such as benzene, toluene, ethyl-benzene, isomeric xylenes, styrene (BTEXs), phenols and carboxylic acids which constitute a significant class of air pollutants in tested paints. Experimental results showed that toxic air pollutants emissions from selected paints were more concentrated at the source. The design models used showed that pollutants emissions from applied water-based paint followed Quadratic model and that RH, t and PM were significant to particulate matter emission factor (PM-EF) while RH, TVOC and PM were significant to total volatile organic compound emission factor (TVOC-EF). For oil base paint, the design models used showed that pollutants emissions from applied paint followed 2FI model and that T, t, TVOC and PM were significant to particulate matter emission factor (PM-EF) while T, t, TVOC and RH were significant to total volatile organic compound emission factor (TVOC-EF). This study established that for applications in indoor environments, water-based paint is better and safer than oil-based paint with regards to safe period. Also, factors influencing toxic air pollutants emissions from common commercial paints applied in the indoor environment were evaluated. In addition, a quick, easy, and low-cost model was designed to forecast the emissions of toxic air pollutants from paint products in indoor environment based on time and distance. Further, methods and techniques for reducing and controlling toxic air pollutant concentrations from commercial paint applications were highlighted, and current developments to address and enhance indoor air quality (IAQ) were outlined.
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    Simulation and optimization of blending ratio of fossil fuel and scrap tyres in cement production
    (Department of Chemical Engineering, Falculty of Technology, Obafemi Awolowo University., 2022) ABUBAKAR, Waheed Adewole
    This study determined the effect of scrap tyres as a complementary fuel and fossil fuel mixtures on kiln operation stability, desired specific heat value and impact on environment, optimised the complementary fuel to fossil fuel mixture ratio and developed mathematical models for minimum energy consumption and emissions. These were with a view to achieving energy and cost savings by co-consumption of scrap tyres with fossil fuel in cement manufacturing facility. The samples of limestone, which is the basic raw material, were obtained from different mines and analysed to determine their compositions using X-ray Fluorescent equipment. The compositions of fossil fuel and scrap tyres were obtained from Nigerian Gas Company and the literature respectively. The prices of raw materials and fuels were obtained from BUA Cement Plc’s Procurement department. The composition of raw materials, fuels and their prices were inserted into the mathematical model equation to determine the minimum cost of cement manufacturing. The modelling optimized the blending ratio of fossil fuel and scrap tyre and takes into account the stable kiln operation by ensuring the clinker parameters were within the targeted values and minimum gas emission. The results of Particle Swarm Optimization modelling showed 36% of fossil fuel was substituted with scrap tyres as a complementary fuel. The cost of manufacturing 1 tonne of cement was $69 using fossil fuel with the blend of scrap tyre compared to using fossil fuel only, which was $73 per tonne. Simulation results showed a reduction in specific heat consumption and SO2 gas emission as the scrap tyre substitution increases. Optimum blending of fossil fuel and scrap tyres was achieved with all the parameter within the targets. This study concluded that blending of scrap tyres as a complementary fuel with fossil fuel in rotary kiln reduces the cost of cement manufacturing without compromise in the product quality and operation stability.
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    Simulation and optimization of blending ratio of fossil fuel and scrap tyress in cement production
    (Department of Chemical Engineering, Faculty of Technology, Obafemi Awolowo University., 2022) ABUBAKAR, Waheed Adewole
    This study determined the effect of scrap tyres as a complementary fuel and fossil fuel mixtures on kiln operation stability, desired specific heat value and impact on environment, optimised the complementary fuel to fossil fuel mixture ratio and developed mathematical models for minimum energy consumption and emissions. These were with a view to achieving energy and cost savings by co-consumption of scrap tyres with fossil fuel in cement manufacturing facility. The samples of limestone, which is the basic raw material, were obtained from different mines and analysed to determine their compositions using X-ray Fluorescent equipment. The compositions of fossil fuel and scrap tyres were obtained from Nigerian Gas Company and the literature respectively. The prices of raw materials and fuels were obtained from BUA Cement Plc’s Procurement department. The composition of raw materials, fuels and their prices were inserted into the mathematical model equation to determine the minimum cost of cement manufacturing. The modelling optimized the blending ratio of fossil fuel and scrap tyre and takes into account the stable kiln operation by ensuring the clinker parameters were within the targeted values and minimum gas emission. The results of Particle Swarm Optimization modelling showed 36% of fossil fuel was substituted with scrap tyres as a complementary fuel. The cost of manufacturing 1 tonne of cement was $69 using fossil fuel with the blend of scrap tyre compared to using fossil fuel only, which was $73 per tonne. Simulation results showed a reduction in specific heat consumption and SO2 gas emission as the scrap tyre substitution increases. Optimum blending of fossil fuel and scrap tyres was achieved with all the parameter within the targets. This study concluded that blending of scrap tyres as a complementary fuel with fossil fuel in rotary kiln reduces the cost of cement manufacturing without compromise in the product quality and operation stability.
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    Studies of some quality parameters of dried paraquetina nigrescens. L. leaf
    (Department of Food Science and Technology, Faculty of Technology, Obafemi Awolowo University., 2023) AYODELE, Esther Adeyinka
    The study investigated the drying kinetics of African parquetina (Parquetina nigrescens) leaves at three different temperatures and evaluated the effect of various drying conditions on its phytochemical, proximate, antioxidant and mineral properties. It also assessed the storage stability of the dried leaves. These were with a view to examining the effect of using various drying temperatures on the chemical composition and rehydration assessment of Parquetina nigrescens leaves. Freshly harvested Parquetina nigrescens young leaves were destalked, washed, drained and sliced. Leaves were sun dried and oven dried at 50, 60 and 70 oC and weighed at 5, 10, 15, 30 and 60 mins intervals until a sample weight remained unchanged. The dried samples were pulverized into fine powder particle size. Drying data obtained were fitted into five thin layer drying models (Newton, Page, Henderson and Pabis, Logarithmic and Modified Henderson and Pabis). The phytochemical, proximate, mineral and antioxidant properties in both fresh and dried Parquetina nigrescens leaves were determined in accordance with standard procedures. Rehydration capacity was determined at four temperature levels of 30, 60, 70 and 80 o C. The data generated in this study were examined using appropriate descriptive and inferential statistics. The results obtained showed that moisture content reduced as temperature and time increased. The effect of drying temperature on the leaves was significant (p<0.05) up to 105 min after which the drying weight was constant. The proximate composition of the dried leaves indicated; crude protein, total ash, moisture content, crude fibre, fat and carbohydrate content in the range of 5.09 - 5.85%; 51- 0.64%; 9.14 - 9.55%; 1.75 - 1.93%; 1.10 - .24% and 79.47 - 82.06% respectively. For mineral constituents, it was found that: calcium, phosphorus, sodium, magnesium, zinc, copper and iron were in the range of(5.05-5.14, 0.08-0.81, 80.18-87.17, 3.31- 4.64, 0.67-8.02, 1.33- 2.11 and 0.22-0.96 xvii mg/100g, respectively). The antioxidant properties of the leaf samples indicated that Ferric Reducing Power (FRAP), Metal Chelation Activity (MCA) and1,1diphenypicylhydrazine (DPPH) are in the range of 0.27- 0.40, 53.16 -71.45 and 20.14 - 37.67, respectively. The pH of the stored dried leaves ranged between 6.15 - 7.56. The phytochemical properties present, indicated (flavonoid 151.41-170.77mg/100g), (phenol12.50 –17.81mg/100g), (glycosides 0.62 –5.54mg/100g), (alkaloid 0.22-0.98mg/100g), (triterpene 165.08-185.92mg/100g (steroid111.1 - 127.0mg/100g), (tannin 2.6-6.00mg/100g), (saponin 0.94- 1.01mg/100), (terpenoid 1.10 - 17.81mg/100g) and (coumarin 4.12--15.43mg/100g) respectively. In addition, it was confirmed that storage time lower the rehydration capacity and high in rehydrating temperatures, increased the rehydrating capacity of the dried leaves. The study concluded that sundried samples had better quality attributes than oven dried samples while oven dried leaves at 70 o C indicated the best quality out of the three temperature used.
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    Techno- Economic analysis of small hydropower development in Southwestern Nigeria.
    (Depatment of Technology management, Faculty of Technology, Obafemi Awolowo University., 2014) Abe Oloruntoba Williams
    The study identified the available dams and assessed the barriers to small hydropower plant systems in southwestern Nigeria, surveyed available technologies for small hydropower plant production of electrical energy and assessed the engineering economics and human capability of small hydropower plant.
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    Techno-Economic assessment of off grid Hydrokinetic Power infrastructure for urban residential development initiatives in Calabar, Cross River State
    (Faculty of Technology, Obafemi Awolowo University, 2024) Leonard Unimke UGI
    This study determined the electricity demand for urban residential development initiatives in Calabar, Cross River State, established the technological specifications for hydrokinetic power development for the urban residential development initiatives and assessed the economic viability of the hydrokinetic power infrastructure. These were with a view to promoting the adoption of hydrokinetic power infrastructure needed for the urban residents in Calabar, Cross River State, Nigeria. The study was carried out in three different selected urban residential areas, electricity audits of the selected urban residential development initiatives was carried out to obtain their power loads and total time of use. The data obtained was used to determine the electricity loads and energy demand. The obtained results served as the benchmarks for the design of the hydrokinetic power infrastructure. Data on technological specifications for the development of the hydrokinetic power infrastructure was obtained from journal articles and reports of the Cross River Urban-Rural Authority. The information obtained included the location coordinates, the lengths and widths of the river, and the river flow velocity. The specific location with its coordinates was mapped out using geographical positioning system (GPS). Information on appropriate turbine specifications and allied electrical components such as transformers came from equipment vendors and literature. Technological specifications for an alternate diesel power generation and CO2 emission savings were elicited from the International Energy Agency (IEA). The data obtained was analysed using energy planning and foresight analyses methodology. The economic viability of the hydrokinetic power infrastructure was determined using capital and operations costs, interest rates, and project time duration amongst others. The data obtained was analysed using life cycle and engineering economy analyses. The results showed that 815 housing units in the selected area had 9.2 MW power load demand with projected energy consumption of 51.8 MWh/day. The hydroquest turbine was found to be most suitable for the extraction of hydrokinetic power from the Calabar River. From the design calculations, 128 numbers of the suitable turbine (80kW hydroquest 2.80) were needed to produce the said electricity demand of 9.2 MW. The hydrokinetic requires a total investment cost of forty-one billion, nine hundred and three million four hundred and fifty naira (₦41,903.45 ×106). The investment required an annual operating cost of four billion five hundred and twelve million two hundred thousand (₦4,512.20 ×106). The levelized cost of HKP-based electricity was found to be ₦68.99/kWh at present. Subsequently, the levelized cost of HKP-based electricity for the first year of operation was ₦82.79/kWh. The estimated minimum revenue for the HKP-based electricity project was six billion five hundred and twenty-six million naira only (₦6,526.00×106) leading to investment recovery on the 7th year of 25 years life cycle of the project. The result also indicated that 528 metric tons of CO2 can be saved from the atmosphere over the 25 years life cycle of the project. The study concluded that, the establishment and development of hydrokinetic power plant in Calabar is technologically and economically viable.
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    Technological assessment of the liquefied petroleum gas (LPG) retail industry in Osun State, Nigeria
    (Department of Electronic and Electrical Engineering, Faculty of Technology, Obafemi Awolowo University., 2022) AJAYI, Oluwasola Matthew
    This study examined the technological assessment of Liquefied Petroleum Gas retail industry in Osun state. The objectives are to identify the LPG nozzle dispensing technology among owners, the extent and level of adoption and critical technological issues in the LPG retail industry. These were with the view of ensuring policy and standard management practice on strategies for the running of successful LPG retail industry. The study was conducted in Ile-Ife, Ilesa, Ede and Osogbo which are located in Osun state, south western Nigeria. Data were collected using both primary and secondary sources. The primary source of data included structured questionnaire and interviews. The questionnaire was administered to the owners of 40 LPG retail industry purposively selected from each town, making the total of 160 respondents. The questionnaire was used to elicit information on the identification of nozzle dispensing technology and the extent and level of adoption of these technologies. Information was also obtained on the critical technology issues influencing these technologies. Secondary data which provided information on the various LPG retail industry operations globally in the past years and these were sourced from internet. The data generated from the study were analyzed using appropriate description and inferential statistic. The result of identification of nozzles dispensing technology showed on the frequency table, that high to low cylinder venting dispenser technology has the highest percentage of 57.30% which were the most popularly used within the studied area while one/more nozzle compressor dispenser has 29.3%, Locally fabricated compressor dispenser has 9.3% and single/double automatic dispenser has 4.0%. On the extent and level of adoption of these technologies showed that the result on the frequency table where only high percentage in each town was indicated; the industry that used more than one technology has 48.7% in Ede, the variation in the refiling duration of the technology was 75.0% often observed in Ile Ife. This was because of the difference measurements of Propane cylinders which were xvi to be used abroad are now being used in Nigeria. Health, Safety and Environmental training and maintenance of staff competence of 30.0% were observed in Osogbo, appropriate distance requirement of 100m x 100m of 37.5% and availability of safety equipment of 37.5% were also indicated in Osogbo respectively, operational technology above 10 years in Ile Ife has 32.5%, separation from the surrounding buildings in Ede has 87.5% and the occurrence of fire incident in Osogbo has 10.3%. On the critical technological issues; high to low cylinder venting dispenser has 73.8% which was the highest size of nozzle’s mouth, the system malfunction indicated 68.3% and the high risk of fire incident was 47.6%, air in the refiling hose has 38.9%, bad values has 43.6 % this was commonly observed in some areas and the locally fabricated dispenser showed 100% of no return mechanism in all studied area. The study concluded that the most LPG retail prefer single/double automatic nozzle dispensing technology, if safety procedures and right policies are enforced
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    The use of potassium and magnesium thiosulphate solution for leaching of gold from disposed cell phones.
    (Department of Materials Science and Engineering, Faculty of Technology, Obafemi Awolowo University., 2024) Akpomejero, Tobore Lucky
    This study analyzed and pre-concentrated pulverized samples of printed circuit boards of disposed cell phones. The leaching condition of gold from the pre-concentrated samples was optimized using potassium and magnesium thiosulphate solutions. Electrowinning the solution of the highest gold dissolution was later carried out, followed by analysis of the obtained deposit. This was with a view to extracting gold from printed circuit boards using a less toxic lixiviant. Prior to pre-concentration and leaching, PCBs from discarded cell phones were obtained, pulverized, and analyzed using an energy dispersive spectroscopy (SEM/EDX) to determine whether gold was present. The pulverized material was then pre-concentrated using magnetic separation to eliminate ferrous components. Trioxonitrate (V) and Hydrogen tetraoxosulphate (VI) acids were used to eliminate base metals such as copper, zinc, etc. The residue was then leached separately with the use of Potassium and Magnesium thiosulphate solutions using Copper (II) sulphate and Ammonia as additives. The concentrations of the thiosulphates as well as the additives were varied in order to obtain the leachate with the highest gold dissolution. The obtained leachate was then used as the electrolyte during the electrowinning process which was done with the use of the PG Autostat 302N Potentiometer to obtain a deposit which was further analyzed with the SEM/EDX for the presence of gold. The result of the analyzed sample (before pre-concentration and leaching) showed the presence of gold during the EDX analysis. High gold dissolutions of 0.88 ppm and 0.70 ppm for Potassium and Magnesium thiosulphates respectively were obtained in both cases at the precious metal leaching stage when the maximum concentrations of thiosulphates, ammonia, and least concentration of Copper (II) sulphate were used. The result of the EDX analysis (after electrowinning using the leachate with 0.88 ppm gold dissolution and a stainless steel sample as the working electrode) showed the presence of gold from the deposit on the stainless steel sample. This study confirms that gold can be found in electronic wastes and that it can be profitably extracted with the right concentrations of additives (Copper sulphate and Ammonia) and thiosulphate (magnesium and phosphate), hence, providing a substitute for the extraction of precious metals and, eventually, help manage electronic wastes.