UNIZIK Journal of Engineering and Applied Sciences
Formerly known as the Journal of Engineering and Applied Sciences UNIZIK Journal of Engineering and Applied Sciences (UJEAS) is an international journal published by the Faculty of Engineering, Nnamdi Azikiwe University, Awka. It is a specialized journal aimed at fostering the growth of educational, scientific, and industrial research. UJEAS is a pathbreaking journal that adopts an open-source approach to publication, viewing research as a cooperative enterprise between authors, editors, referees, and readers. You are strongly encouraged to join the journal's community and become a registered reader. As such, you can comment on articles. And, of course, you can always submit a paper as a registered author. Prospective authors can also submit directly to the journal email via ujeas@journals.unizik.edu.ng
Faculty of Engineering, Nnamdi Azikiwe University, Awka Nigeria
Unlocking the Potential: A Detailed Characterization of n-Hexane Extracted Sweet Orange Seed Oil as a Sustainable Industrial Feedstock
This study conducted an extensive characterization of sweet orange seed oil (SOSO), extracted using the Soxhlet method with n-hexane, to evaluate its potential as a feedstock for industrial applications. The extraction produced 41.64% (w/w) of a light-yellow oil containing 0.249% moisture. The characterization revealed that at 40 °C, the kinematic viscosity was 29.450 mm²/s, the refractive index was 1.437 at 30 °C, and the acid value was 9.24 mgKOH/g, indicating a free fatty acid (FFA) content of 4.67 mgKOH/g. The iodine value was determined to be 107.78 meq/100g, suggesting the oil is highly unsaturated. Further tests showed a saponification value of 243.446 mgKOH/kg, a peroxide value of 0.410 meq/g, a specific gravity of 0.920, and a molecular weight of 1114.68 g/mol. The thermal properties included a flash point of 217 °C, a cloud point of 12.0 °C, and a melting point of 3.5 °C. The ester value was 62.019%. The physicochemical properties closely matched those specified in ASTM D6751f, indicating that SOSO could serve as a non-edible substitute for conventional vegetable oils. Gas Chromatography-Mass Spectrometry (GC-MS) analysis showed that 71.35% of the fatty acids were unsaturated, primarily Oleic (4.34%) and Linoleic acids (67.01%), suggesting excellent cold-flow properties and high reactivity for chemical conversion. Additionally, Fourier Transform Infrared (FTIR) spectroscopy identified characteristic ester functional groups at 1745 cm-1, with the C=O (carbonyl) stretching vibration indicating good structural integrity. This comprehensive study concludes that the oil has favorable properties for long-term use across various industries, particularly in biodiesel and bio-lubricant production.
MODELING AND OPTIMIZATION OF THE NOZZLE POSITION OF A CROSS-FLOW HYDRO TURBINE USING BOX-BEHNKEN DESIGN AND MACHINE LEARNING TECHNIQUES
This study employed the Box-Behnken design and machine learning techniques to model and optimize the nozzle position of a cross-flow turbine system. The Box-Behnken design was used to structure the experiment, with nozzle height (365 mm–461 mm), nozzle distance (102 mm–202 mm), and attack angle (0°–40°) as the predictors (independent factors), and efficiency, shaft power, and runner speed as the response variables. A total of 17 experimental runs were obtained from the Box-Behnken design. The experimental design was meticulously followed. The runner speed was measured using a digital tachometer and recorded for each nozzle positional setting, while the shaft power and efficiency were calculated using the appropriate formulae. The responses were optimized, modeled, and analyzed statistically using ANOVA to assess how the nozzle positional factors individually and interactively affect the responses. The results of the RSM optimization were validated using the machine learning algorithm, Sequential Least Squares Programming (SLSQP). Additionally, the responses of the cross-flow turbine were modeled using the Multilayer Perceptron (MLP) algorithm, and its prediction performance was compared to that of the RSM model. This comparison was conducted both graphically and statistically using performance indices such as mean bias error (MBE), root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), t-statistic, coefficient of correlation (r), and coefficient of determination (<!-- [if gte msEquation 12]><m:oMath><m:sSup><m:sSupPr><m:ctrlPr></m:ctrlPr></m:sSupPr><m:e><m:r><m:rPr><m:scr m:val="roman"/><m:sty m:val="p"/></m:rPr>R</m:r></m:e><m:sup><m:r><m:rPr><m:scr m:val="roman"/><m:sty m:val="p"/></m:rPr>2</m:r></m:sup></m:sSup></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri','sans-serif'; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 3.0pt; mso-text-raise: -3.0pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"><!-- [if gte vml 1]><v:shapetype id="_x0000_t75" coordsize="21600,21600" o:spt="75" o:preferrelative="t" path="m@4@5l@4@11@9@11@9@5xe" filled="f" stroked="f"> <v:stroke joinstyle="miter"/> <v:formulas> <v:f eqn="if lineDrawn pixelLineWidth 0"/> <v:f eqn="sum @0 1 0"/> <v:f eqn="sum 0 0 @1"/> <v:f eqn="prod @2 1 2"/> <v:f eqn="prod @3 21600 pixelWidth"/> <v:f eqn="prod @3 21600 pixelHeight"/> <v:f eqn="sum @0 0 1"/> <v:f eqn="prod @6 1 2"/> <v:f eqn="prod @7 21600 pixelWidth"/> <v:f eqn="sum @8 21600 0"/> <v:f eqn="prod @7 21600 pixelHeight"/> <v:f eqn="sum @10 21600 0"/> </v:formulas> <v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"/> <o:lock v:ext="edit" aspectratio="t"/> </v:shapetype><v:shape id="_x0000_i1025" type="#_x0000_t75" style='width:9.75pt; height:12pt'> <v:imagedata src="file:///C:\Users\HP\AppData\Local\Temp\msohtmlclip1\01\clip_image001.png" o:title="" chromakey="white"/> </v:shape><![endif]--> ). The study results showed that each nozzle positional factor influences the efficiency, shaft power, and runner speed of the CFT system. Additionally, it was observed that the nozzle height and attack angle interactively affect the CFT responses. Using the RSM optimization technique, the optimal nozzle position was determined to be: nozzle height = 408.4mm, nozzle distance = 102mm, and attack angle = 5°. At this position, the predicted response values were: efficiency = 91.91%, shaft power = 242.367W, and runner speed = 406rpm. The SLSQP technique validated the RSM findings by identifying a similar optimal nozzle position: nozzle height = 407.99mm, nozzle distance = 102mm, and attack angle = 4.699°. At this position, the predicted response values were: efficiency = 91.962%, shaft power = 242.599W, and runner speed = 405.99rpm. Furthermore, holistic modeling of the CFT system demonstrated that both RSM and MLP models performed well in estimating CFT responses. However, the RSM model surpassed the MLP model, as it had lower MBE, RMSE, and T-statistic values and higher NSE, r, and <!-- [if gte msEquation 12]><m:oMath><m:sSup><m:sSupPr><m:ctrlPr></m:ctrlPr></m:sSupPr><m:e><m:r><m:rPr><m:scr m:val="roman"/><m:sty m:val="p"/></m:rPr>R</m:r></m:e><m:sup><m:r><m:rPr><m:scr m:val="roman"/><m:sty m:val="p"/></m:rPr>2</m:r></m:sup></m:sSup></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri','sans-serif'; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 3.0pt; mso-text-raise: -3.0pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"><!-- [if gte vml 1]><v:shape id="_x0000_i1025" type="#_x0000_t75" style='width:9.75pt;height:12pt'> <v:imagedata src="file:///C:\Users\HP\AppData\Local\Temp\msohtmlclip1\01\clip_image001.png" o:title="" chromakey="white"/> </v:shape><![endif]--> values. Consequently, the developed RSM model is recommended for predicting CFT responses across different nozzle positional factors.
The Mechanical and Morphological Properties of Nano Pineapple Crown Fiber (PCF) incorporated in Polyvinyl Alcohol, Carboxymethyl Cellulose (PVA/CMC) Bio-Nanocomposite for Food Packaging Applications
The essence of this study was to fabricate carboxymethyl cellulose polyvinyl alcohol (PVA/CMC) films and to improve their mechanical and morphological properties by using pineapple crown Nano fiber (PCF) as a reinforcement. The films were developed by incorporating PCF into the PVA/CMC (2:1) in 0wt.%, 3wt.%, 5 wt.%, and 7wt.% respectively, by the solution casting method in water as a solvent and 4.5 wt.% glycerol as a plasticizer. The particle size distribution of the treated pineapple crown fiber (PCF) powder was analyzed by TEM, revealing nanoscale, largely spherical particles ranging from 2.7 to 6.4 nm (average ≈4.5 nm). The dispersion of the Nano PCF contents in the film was analyzed by SEM, and it shows a more uniform dispersion of fibers within the polymer matrix and an enhanced interfacial contact. Thermal stability, degradation properties, and crystallinity were also studied. The biodegradability of cast films was also carried out by the soil burial method, and degradation increased as the number of days went by. 71% and 65% biodegradability was observed in 15 and 30 days for samples with 5wt.% and 3 wt.% PCF respectively. Tensile properties of blended film were tested, and it was found that the tensile strength 27.7MPa, % elongation at break 12.80%, and modulus of elasticity 2299MPa are higher in the blend with 3wt.% (PCF-B) as compared with the neat PVA/CMC film. This result tells the viability of this bio-nanocomposite material to be used in food packaging.
Synthesis, Characterization and Adsorption of methylene blue dye using titanium dioxide nanoparticles
The application of nanomaterial in the reclamation of wastewater has been a trending aspect of research in the recent time. This research work was carried out to investigate the adsorption of methylene blue dye using TiO2 nanoparticles. The TiO2 nanoparticles used in this work was synthesized by sol-gel method using titanium isopropoxide. After the synthesis, the titanium dioxide powder that was obtained and was calcined at 500oC. The titanium dioxide nanoparticles obtained was characterized using SEM, FTIR, and XRD. The FTIR result showed that -OH group, -CH2 group, C═O group and Ti-OTi stretching band played major role in the efficacy of TiO2 nanoparticles. SEM morphology indicates the porous nature of the nanoadsorbent while the XRD confirm the crystalline nature of the nanomaterial. Influence of process variables were investigated and the results indicate that the three factors studied affected the adsorption process. Adsorption isotherm parameters gave good fit to the four models used in this work with R2 values above 0.900. The kinetic studies did not fit well with Pseudo-first-order model but fitted the other three models.
Synthesis of Cellulose Based Carbon Dots from African fan palm (Borassus aethiopum) for Corrosion Inhibition of Mild Steel in HCL
This study investigated the synthesis of lignin-containing cellulose carbon dots (LC-CDs) from African fan palm (Borassus aethiopum) biomass and their application as eco-friendly corrosion inhibitors for mild steel in 1 M HCl solution. The cellulose-rich fibres were treated with alkali and converted into carbon dots through hydrothermal synthesis. The prepared LC-CDs were characterized using UV–Visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and Scanning Probe Microscopy (SPM). Results confirmed the successful formation of spherical carbon dots with particle sizes below 10 nm and abundant oxygen-containing functional groups. Corrosion inhibition performance was evaluated using weight loss analysis, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). The inhibition efficiency increased with concentration and immersion time, reaching optimum efficiencies of 90.8% and 90.7% from weight loss and electrochemical measurements, respectively, at 200 mg/L. Electrochemical studies showed reduced corrosion current density and increased charge transfer resistance, indicating effective adsorption and protective film formation on the steel surface. The results demonstrate that African fan palmderived LC-CDs are sustainable, low-cost, and highly effective green corrosion inhibitors for acidic industrial environments.
Steady-State Security and Voltage Stability Assessment of the Nigerian 330 kv Transmission Network
This study presents a comprehensive steady-state vulnerability assessment of the Nigerian 330 kV, 50-bus, 96-line transmission network, addressing identified gaps in the published power system literature: inadequate dataset validation, sole reliance on first-order iterative solvers, and the absence of contingency analysis. Three research objectives are pursued: (i) geospatial verification of published transmission line parameters using the Haversine formula and Google Maps satellite imagery, specifically the Fakun–Kainji corridor, whose published length of approximately 0.50 km (Bus 34 to Bus 50) is confirmed as physically correct by GPS-corroborated field coordinates; (ii) correction of systematically erroneous shunt susceptance values in the dataset of Ugwuanyi et al. (2024), wherein published B values were found to represent series branch admittance rather than shunt charging susceptance; and (iii) capping of Bus 45 (Geregu) generation at its documented 435 MW installed capacity. This research utilizes MATLAB 2023a with the MATPOWER 8.1 toolbox to implement a robust Newton-Raphson power flow solver, independently cross-validated using PandaPower, The corrected and validated base case yields a total active power loss of 55.54 MW (system efficiency: 98.78%) and identifies five buses with critical overvoltage violations driven by the Ferranti Effect: Maiduguri/Bus 28 (1.3166 p.u., +0.2666 p.u. above limit), Damaturu/Bus 26 (1.2694 p.u.), and Yola/Bus 31 (1.2082 p.u., highest L-index: 0.6603). Sensitivity analysis under load scaling (KL = 0.9 to 1.1) confirms that overvoltage severity is inversely proportional to loading level, intensifying under light-load conditions. N-1 contingency analysis of all 96 lines identifies Lines 79 and 80 (Lafia–Jos) as the most critical converged outages (max FVSI = 0.9916), while eight lines cause voltage collapse upon individual removal. N-2 analysis identifies the simultaneous outage of Lines 19 and 79 as the most severe credible dual-contingency scenario (max FVSI = 1.0174). These findings confirm that the North-East corridor is structurally vulnerable and that the Lafia–Jos parallel circuits represent the system’s single greatest reliability risk. Immediate deployment of shunt reactors at Maiduguri and Damaturu and reinforcement of the Lafia–Jos corridor are strongly recommended.
Optimization of Solvent Extraction of African Pea Seed Oil Using Ethanol and Petroleum Ether for Bioaviation Fuel Feedstock
Extraction of oil from African pea seeds for jet fuel sustainability is vital in promoting renewable energy. This work focuses on extracting oil from African pea seeds by optimizing the extraction process parameters using response surface methodology (RSM). Solvent extraction method was used with ethanol and petroleum ether as solvents. Three independent extraction parameters; particle sizes (0.15, 0.3, 0.45 mm), temperature (40, 60, 80 °C) and time (30, 60, 90 min) were considered. The highest oil yield was 6% and 18.4% for ethanol petroleum ether respectively. The optimal conditions: particle size, temperature and extraction time, were recorded at 0.3 mm, 60 oC and 123.9 min respectively for ethanol and 0.45 mm, 40 oC and 120 min respectively for petroleum ether. Quadratic model is suggested for both solvents as the best fit with adjusted R² of 0.9143 and 0.8571 and predicted R² of 0.7452 and 0.7822 respectively, indicating good agreement between the two (predicted and observed). Temperature (B), time (C), and interaction terms (AB, AC, BC) are significant for petroleum ether with temperature and particle size having the most significant effect on oil yield, while Particle size (A), time (C), and squared terms (B² and C²) are significant in affecting ethanol. Time (C) has the most substantial effect (F-value of 27.38), meaning the longer the extraction time, the higher the yield for ethanol as solvent. Consequently, the results showed that Petroleum ether gave a better yield compared to ethanol.
Low-Carbon Reinforced Concrete Beams Using Recycled-Aggregate Concrete and Industrial-Waste Binders: Experimental Bond-Strength and Flexural Performance Assessment
The construction sector is one of the largest contributors to global carbon dioxide emissions, with Portland cement production accounting for roughly 8% of anthropogenic CO2 annually. This paper presents an experimental investigation into the bond strength and flexural performance of reinforced concrete beams made from recycled coarse aggregate concrete incorporating industrial-waste supplementary cementitious materials, specifically ground granulated blastfurnace slag conforming to EN 15167-1, fly ash conforming to EN 450-1, and silica fume conforming to EN 13263-1. Four concrete mixes were evaluated: a normal concrete control, two recycled aggregate concrete mixes with 50% and 100% coarse aggregate replacement, and a blended-binder mix with 100% recycled aggregate and combined supplementary cementitious material substitution of 44.4% by cement mass. Beams measuring 150 mm x 250 mm x 2000 mm were tested under four-point bending at 28 days, with companion cylinder and pull-out specimens tested in parallel. The characteristic compressive strength of the 100% recycled aggregate mix fell 15.8% below the normal concrete control (34.7 vs. 41.2 MPa), while the blended-binder mix surpassed normal concrete by 5.6% at 43.5 MPa. Experimental bond strength in the blended-binder mix reached 10.53 MPa, exceeding normal concrete by 7.0%, while the 100% recycled aggregate mix showed a 16.6% reduction. Eurocode 2 design bond values proved conservative relative to measured results across all mixes, with the fib Model Code 2010 showing markedly closer agreement. The blended-binder mix achieved an ultimate load of 134.7 kN and a ductility index of 4.12 against normal concrete's 3.41. Embodied carbon analysis confirmed a 28.3% reduction for the blended-binder mix relative to the normal concrete control.
Investigation and Modelling of Slurry Performance of Ordinary Portland Cement Blended with Metakaolin and Sawdust-ash for Oil Well Cementing
Oil well Cementing involves placing a special compound of cement grout formulated from constituents with relative weight to that of cement in the annulus between the casing and the adjacent rock formation to strongly join the casing to the formation. One of the challenges usually encountered during deep drilling, especially in a High-Pressure-High Temperature (HPHT) environment, is the sustenance of wellbore integrity in terms of serviceability over long operation period. In this study, the viability of optimizing slurry performance using Sawdust Ash (SDA) and Metakaolin (MK) as a blend to Ordinary Portland Cement (OPC) allows combinations and percentages replacement of the Ordinary Portland Cement (OPC) with Metakaolin for 10%,12.5% and, 15% while Sawdust ash at 0%, 5% 10% making up for 10 to 25% of both pozzolan incorporation to modify the properties of ordinary Portland cement, and providing an efficient, cheaper oil well-cementing material. Materials for the study were synthesized and characterized based on physical, chemical, and pozzolanic properties. The slurry and mechanical properties were studied based on the mix formulation generated from design of experiment (DOE) using two domains three interactive factors (23) level factorial model following the specifications of (API SPEC 10A and 10B). Metakaolin blend with OPC alone at 15% was detrimental to rheology performance but incorporating Sawdust Ash up to 10% with Metakaolin at both low and high blend (10% and 15%) improved the slurry and mechanical performance; yielding an optimal blend sample of (75%OPC, 15%MK, 10%SDA).
Influence of Web Thickness on the Compressive Strength of Sandcrete Hollow Blocks
The prevalence of buildings with poor structural stability in developing nations like Nigeria is a growing concern, primarily driven by the use of substandard construction materials. As two-cell hollow sandcrete blocks are a dominant masonry unit in the region, understanding the impact of their geometry—specifically web thickness—on structural integrity is critical. This study investigates the influence of varying web thicknesses (20 mm, 25 mm, 35 mm, 40 mm, 45 mm, and 50 mm) on the engineering properties of nine-inch sandcrete blocks produced with different cement-sand ratios (1:12, 1:14, 1:16, and 1:20). A total of 216 samples were subjected to three curing regimes: air curing, water sprinkling, and water submersion. Experimental results revealed that bulk density and compressive strength increased with higher web thickness and richer cement content, while water absorption decreased. Bulk density ranged from 1627.49 kg/m³ to 1997.87 kg/m³, and water absorption varied between 230.60 kg/m³ and 289.34 kg/m³. At 28 days, compressive strengths ranged from 0.59 N/mm² to 2.88 N/mm² across different curing methods. The study concludes that blocks with web thicknesses of 35 mm and above met the 2.1 N/mm² compressive strength criterion experimentally, confirming that the NIS 978-mandated minimum of 50 mm for 9-inch load-bearing blocks provide an adequate structural safety margin. Furthermore, water-submerged curing was identified as the most effective method for enhancing block performance. These findings reinforce the importance of strict compliance with the NIS 978 minimum web thickness of 50 mm, alongside richer mix proportions, to ensure structural safety and durability.
Design and Simulation Validation of a Liquid–Liquid Heterojunction Triboelectric Nanogenerator Integrated with Photovoltaic Modules for All- Weather Energy Harvesting
This study presents the design and simulation validation of a liquid–liquid heterojunction triboelectric nanogenerator (LLH- TENG) integrated with photovoltaic (PV) modules for all-weather energy harvesting. The proposed system utilizes immiscible liquid interfaces within a horizontal microchannel to enable durable and transparent energy conversion under rainfall-induced excitation. A finite element model based on Poisson’s equation was developed to evaluate the electrostatic behavior of the system. Simulation results demonstrate a stable electric potential distribution across the microchannel and a linear increase in output voltage with excitation frequency (1–5 Hz). The electric potential varied from approximately 1.0 V to 0 V across the microchannel, while the output voltage increased from approximately 0.2 V at 1 Hz to 1.0 V at 5 Hz, confirming the feasibility of LL-H-TENG architectures as durable and complementary energy harvesting systems for photovoltaic applications.
Automated Skin Disease Detection System Using the YOLOV8 Deep Learning Model
Skin diseases are a significant worldwide health burden, with conditions varying from benign (acne) to potentially lethal (melanoma). Timely and accurate detection plays a critical role in treatment and patient outcomes; unfortunately, traditional methods of detection are heavily reliant on dermatologists, taking time, being subjective and not always available. To overcome these limitations, this research aims to develop an automated real-time skin disease detection system based on the YOLOv8 deep learning approach. The dataset used is a Kaggle dataset of 22 skin diseases. The images were resized, normalised, converted to YOLO format and data augmentation was applied to enhance generalisability. We used precision, recall, F1-score, and mean Average Precision (mAP) for model evaluation. The model's performance with a precision of 90.7%, recall of 89.2%, F1-score of 89.9%, and mAP@0.5 of 0.918 indicated robust performance and detection accuracy. Per-class analysis also confirmed strong performance for diseases that have distinct features, but some misclassifications were noted for similar diseases. Overall, the system shows that YOLOv8 performs well for real-time detection and classification of skin diseases. The system’s speed and accuracy suggest potential for integration into mobile health apps, telehealth services, and decision support systems, though real-world deployment validation remains as future work.
An Intelligent Facial Recognition System Developed for Insurgency Investigation and Surveillance Applications Using Deep Learning Techniques
In this paper, we report the development and performance evaluation of a smart facial recognition system for insurgency investigation and monitoring. The system uses state-of-the-art deep learning methods, including You Only Look Once version 8 (YOLOv8) for real-time face detection and FaceNet with triplet loss for extraction and matching. The system was trained and evaluated using a large dataset, CASIA-WebFace, with 494,414 images of 10,575 individuals. The system is built upon the Extreme Programming (XP) development process, allowing for iterative development, testing and responsiveness to security needs. The system was deployed on a cloud platform with GPUs to accelerate the model training and inference process. The evaluation results show that the proposed system is efficient and effective under different practical scenarios. The face detection module has an overall mean Average Precision (mAP@0.5) of 94.4% with real-time processing speed, while the face recognition module has an accuracy of 96.9%, Area Under the Curve (AUC) of 0.992, and Equal Error Rate (EER) of 3.1%. The system performed well in extreme conditions such as low resolution, occlusion and pose variations. These results demonstrate the potential of combining deep learning-based detection and recognition models for accurate person identification. Our next steps include further optimising performance in extreme scenarios, minimising computational demands, and introducing explainable AI methods to make the system more transparent and interpretable.
Reconfigurable Intelligent Surface Assisted Covert Communication for Smart Grid Systems
In this paper, we consider a reconfigurable intelligent surface (RIS)-assisted covert communication for enhancing the security of the smart grid system. Specifically, we exploit the reconfigurability potentials of the RIS and develop an intelligent covert communication system to enhance the security of the communication within the advanced metering infrastructure (AMI) of the smart grid system. The design objective is to maximize the covert rate at the smart meters while satisfying the maximum transmit power constraint of the transmitter, the constant modulus constraints of the RIS, and to minimize the probability of the monitor/attacker detecting the transmitter’s transmission behavior, thus ensuring the secure transmission of private information. We adopt some convex approximation techniques to reformulate the resulting problem into a relaxed convex optimization problem. We proposed a low-complexity and sub-optimal solution based on the alternating optimization approach. Simulation results are provided showing the effectiveness of the proposed intelligent covert communication system as compared to the other baseline schemes
Molinillo Seed (Hura crepitans) Subjected to Different Drying Techniques and the Effects on the Bio-oil Quality Potentials
This study assessed the impact of different drying processes on the bio-oil yield and physicochemical parameters of molinillo seed (Hura crepitans), an underused non-edible oilseed with promise for renewable energy applications. Using a complete randomized design with three separate trials, seeds were dried by oven, vacuum, solar and sun, with an undried sample that served as control. Whilst solar and sun drying occurred in ambient settings, oven and vacuum drying were carried out at 40, 50, 60, and 70 °C respectively. Soxhlet extraction with n-hexane was used to extract bio-oil, and the oil yield was calculated. Using conventional AOAC and ASTM procedures, as well as some modified methods, the extracted oils were examined for acid value, saponification value, iodine value, peroxide value, specific gravity, and flash point. Analysis of variance was used to statistically examine the data at an accuracy level of 95%. The findings demonstrated significantly increased oil yield with the oven and vacuum drying, where vacuum drying generally yielded more stable oil, in comparison to solar and sun drying. Oven drying at 40°C yielded the maximum oil output (49.70%), while sun-dried sample yielded the lowest (36.97%). Oils with reduced acid and peroxide values, and improved oxidative stability due to reduced moisture were also, consistently obtained by the vacuum drying. Iodine values (83.0–87.5 g I₂/100 g) and saponification values (193.55–200.30 mg KOH/g) showed suitability of the oil for industrial uses, such as, the manufacturing of soap and biodiesel.
Design, implementation and performance evaluation of a low cost AC-DC converter trainer for engineering education
This study presents the design, implementation, and performance evaluation of a low-cost, modular AC–DC converter trainer developed to enhance practical instruction in electrical power conversion. In contrast to conventional AC–DC trainer systems, which are often expensive, rigid, and limited in measurement accessibility, the proposed design incorporates a flexible architecture with multiple regulated outputs and accessible test points for real-time observation of circuit behaviour. The system converted a 220–240 V AC mains supply into regulated DC outputs through a step-down transformer, full-wave bridge rectifier, filter capacitor network, and linear voltage regulators (7805, 7812, and LM317). The design process was supported by detailed analytical modeling, including transformer rating selection, rectifier peak voltage estimation, ripple minimization, capacitor sizing, and regulator thermal considerations. The key contributions of this work included the development of a cost-optimized trainer suitable for resource-constrained laboratories, the integration of fixed (5 V and 12 V) and adjustable (1.3–19 V) outputs within a single platform and the provision of enhanced measurement nodes to improve pedagogical effectiveness. Experimental results under no-load and load conditions indicated an unregulated DC output of 15.92 V, ripple voltage below 0.5 V, and stable regulated outputs across all channels. The system achieved an efficiency range of 75% – 78%, which is comparable to or slightly higher than the 70% – 75% typically reported for existing linear AC–DC trainer designs. These results demonstrate that the proposed trainer meets standard performance requirements while offering improved functionality, affordability, and instructional versatility. The system therefore provided a novel and relevant contribution to engineering education, particularly in technical institutions where cost, accessibility, and hands-on learning are critical considerations.
Fuzzy PID–Based Automatic Irrigation Control for Enhanced Agricultural Performance
This paper presents a Fuzzy PID–based automatic irrigation control system aimed at improving agricultural performance through intelligent water management. A dynamic model of the irrigation process was developed and implemented in simulation to integrate soil moisture dynamics, crop type, and water flow characteristics. The proposed controller combined conventional PID control with fuzzy logic tuning to enhance adaptability under varying environmental conditions. Simulation studies were carried out to compare the proposed Fuzzy PID controller with a conventional/manual control approach using key performance indices such as response time, overshoot, steady-state error, and moisture regulation accuracy. Results showed that the Fuzzy PID system achieved faster settling time, smoother response, and near-zero steady-state error, with improved soil moisture tracking under different crop conditions. To validate the simulation, an experimental prototype was developed using soil moisture sensors, a microcontroller-based control unit, and an automated pump system. Experimental results closely matched simulation predictions, confirming reliable real-time performance and robustness of the controller. Quantitatively, the proposed system reduced water overflow by 100%, improved soil water level regulation by 21%, optimized water supply rate by 9%, and enhanced pump control efficiency by 22% compared to the conventional method. Overall, the results demonstrated that the Fuzzy PID–based irrigation system provides efficient, stable, and precise water management, making it a viable solution for smart agriculture applications.
Improving battery technology using ANN based ultracapacitor
The paralytic form of business activities that mostly depended on battery for their daily routine business were caused by these factors low energy storage capability, slow charge rate, limited discharge capability, high internal resistance, excessive voltage sag, thermal instability, short operational lifespan, rapid aging, poor power handling, inefficient energy conversion, over-dependence on battery, load fluctuation stress, poor response to transients, ineffective energy management and high self-discharge. This was overcoming by introducing improving battery technology using ANN based ultracapacitor. To perfectly achieve this, it was done in this manner, battery technology was characterized and the causes of poor battery technology was established, conventional SIMULINK model for battery technology was designed and ANN was trained in the Causes of Poor Battery Technology Performance for an effective performance. Then, SIMULINK model for ultracapacitor was designed, SIMULINK model for improving battery technology using ANN based ultracapacitor was equally designed and the results obtained were validated and justified. The results obtained were the conventional Low energy storage capability that causes poor battery technology performance was28 J·kg⁻¹ ×10³. On the other hand, when an ANN based ultracapacitor was integrated into the system, it simultaneously improved to33.8 J·kg⁻¹ ×10³ and the conventional Load fluctuation stress that causes poor battery technology performance was17A. Meanwhile, when an ANN based ultracapacitor was imbibed into the system, it instantly reduced to15A. Finally, with these results obtained, it meant that the percentage improvement in battery technology when ANN based ultracapacitor was incorporated into the system was11.8%.
Development of sensitivity index-based technique for unified power flow controller placement with contingency analysis on Nigeria 330Kv transmission network
Persistent power failure that disrupted business activities was mainly caused by poor placement of the Unified Power Flow Controller (UPFC) due to voltage instability in the Nigerian 330 kV transmission network. This study developed a Sensitivity Index–Based Technique for Optimal UPFC Placement with Contingency Analysis to improve system stability. Load flow analysis was first conducted to identify weak buses whose voltage levels fell outside the acceptable stability range of 0.95 through1.05 p.u. A conventional UPFC placement model was designed and compared with the proposed sensitivity index–based technique implemented using a SIMULINK model. Results showed that the conventional system produced a bus voltage of 0.909 p.u. at Bus 4 and line loading sensitivity of 75%, indicating instability. However, when the proposed technique was applied, the voltage improved to 1.05 p.u. and line loading sensitivity increased to 90%. This represents a 15% improvement in system performance, demonstrating that the sensitivity index–based technique significantly enhances UPFC placement and voltage stability in the Nigerian 330 kV transmission network.
Development of an artificial intelligence model for predicting students’ performance in an engineering department of a Nigerian university
Students seeking admission into Nigerian tertiary institutions are required to possess some requirements. However, the efficacy of these requirements in predicting students’ performance has been a subject of discussion. This study examines the effectiveness of current admission requirements in predicting academic performance among engineering students in a Nigerian university. Using data from 340 students admitted between 1996 and 2016, variables such as age, gender, UTME scores, O’Level results, and final CGPA were analysed. With Microsoft Excel and Python, Data pre-processing was carried out. Multiple machine learning models that include Support Vector Machine, Decision Tree, Random Forest, Naïve Bayes, and K-Nearest Neighbours were developed using 311 training samples. To enhance classification accuracy, a One-Vs-One binary classifier based on Decision Tree networks was implemented for three performance categories. Pearson correlation analysis indicated a very weak relationship (0.0075) between UTME scores and CGPA, signifying that UTME alone is a poor predictor of academic performance. But, WAEC scores (0.32), year of birth (0.31), and year of O’Level examination (0.29) showed relatively stronger correlations with CGPA. The exploratory analysis confirmed that the current admission criteria may be inadequate, and a combination of other factors are likely to be better predictors of students’ performance. The resulting ML model which explored broader variables offers a more effective decision support tool for processing undergraduate admissions in Nigerian universities.
Synthesis and Structural Characterisation of Polyaniline (PANI)- Iron oxide (Fe2O3), nanocomposites for Optoelectronics application
In this investigation, polyaniline (PANI), Iron oxide (Fe2O3) nanoparticles and polyaniline- Fe2O3 nanocomposites were successfully synthesized by chemically oxidative polymerization of aniline in the presence of hydrochloric acid using ammonium persulfate as an oxidizing agent. The purpose of this study is to synthesize and investigate polyaniline/ iron oxide nanocomposite for optoelectronics application. The synthesized nanocomposite was characterized to ascertain possible applications of the nanocomposite. The x- ray diffraction (XRD) analysis was carried out using x-ray diffraction machine. The results of the structural analysis showed that the formed polyaniline is a polymer with peak <!-- [if gte msEquation 12]><m:oMath><m:r>2</m:r><m:r>θ</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> at<!-- [if gte msEquation 12]><m:oMath><m:r> 25.36</m:r><m:r>°</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> . X – ray diffraction pattern of iron oxide nanoparticles shows that the fabricated iron oxide nanoparticles are of rhombohedral phase of iron oxide with mineral name Hematite and corresponding to JCPDS file number (00 – 033 – 0664). Two theta angles of <!-- [if gte msEquation 12]><m:oMath><m:r>33.15</m:r><m:r>°</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> , <!-- [if gte msEquation 12]><m:oMath><m:r>35.70</m:r><m:r>°</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> , <!-- [if gte msEquation 12]><m:oMath><m:r>54.10</m:r><m:r>°</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> and <!-- [if gte msEquation 12]><m:oMath><m:r>64.00</m:r><m:r>°</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> were obtained corresponding to miller indices of [104], [110], [116] and [300] respectively. The average crystallite size of <!-- [if gte msEquation 12]><m:oMath><m:r>20.68 </m:r><m:r>nm</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> was obtained for Fe2O3. PANI/Fe2O3 nanocomposites formed have structural phase of iron oxide hydroxide with mineral name Goethite belonging to Orthorhombic crystal structure with space group Pbnm and JCPDS file number (00 – 029 – 0713). Average crystallite sizes of <!-- [if gte msEquation 12]><m:oMath><m:r>8.03 </m:r><m:r>nm</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> , <!-- [if gte msEquation 12]><m:oMath><m:r>7.68 </m:r><m:r>nm</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> , <!-- [if gte msEquation 12]><m:oMath><m:r>12.85 </m:r><m:r>nm</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> and <!-- [if gte msEquation 12]><m:oMath><m:r>13.91 </m:r><m:r>nm</m:r></m:oMath><![endif]--> <span style="font-size: 11.0pt; line-height: 115%; font-family: 'Calibri',sans-serif; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; position: relative; top: 5.5pt; mso-text-raise: -5.5pt; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> were obtained for different Fe2O3 compositions of polyaniline matrix.These results obtained suggest the possibility of using the material in optoelectronics devices like LEDs, solar cells, transducers, and photodetectors.
Speech Emotion Recognition System for Human-Machine Interaction on Edge–Cloud System
Speech emotion recognition (SER) is another major area of affective computing where machines are also capable of detecting and responding to human emotions real time. Nevertheless, it has been found that implementing deep learning-based SER systems on low-power microcontrollers is still a challenge because of computation and memory constraints, and inference time. The research paper describes the design and implementation of an AI-based SER system to provide human-machine interaction (HMI) with the help of an ESP32 microcontroller, an INMP441 digital MEMS microphone, and a MAX98357A audio output module. Preprocessing of speech signals was done by resampling, normalization, and trimming of silences and, features were extracted with Mel-Frequency Cepstral Coefficients (MFCC), Linear Predictive Coding (LPC), and a combined MFCC+LPC representation. The RAVDESS dataset was trained and tested using Convolutional Recurrent Neural Networks (CRNN), Convolutional Neural Networks (CNN), and Recurrent Neural Networks (RNN). The experimental results showed that the CNN model with hybrid MFCC + LPC features had the most favorable performance with an accuracy of 92.01%, precision of 92.11%, recall of 92.52%, and F1-score of 92.03% relative to the RNN and CRNN architecture. The system was shown to be able to perform stable real-time inference at a latency of less than 400 ms, confirming its applicability to embedded applications. These results establish the practicability of successful implementation of high-performing SER systems on the resource-constrained platforms, and present applications in assistive robotics, healthcare, education, and emotion-sensitive IoT devices
Plant Spacing and Stand Density Effects on Aphid–Braconid Wasp Dynamics in Okra (Abelmoschus esculentus) in Benin City, Edo State
Aphid infestations represent a major constraint in okra production, yet their population dynamics are strongly influenced by crop configuration, growth stage, and prevailing weather conditions. Field experiment using a Randomized Complete Block Design (RCBD) was conducted to assess the effects of plant spacing and stand density on aphid abundance and associated parasitoid. Results indicated that plant spacing and stand density did not significantly (p ˃ 0.05) affect aphid populations, although numerically higher infestations were observed under closer spacing (40 × 25 cm). In contrast, aphid abundance varied significantly across weeks after sowing (WAS), with populations remaining low at 2–3 WAS, rising sharply from 4–6 WAS, and peaking between 7–10 WAS. Pooled aphid populations across treatments reached maximum density (1202.00 individuals/five plants) at the 43rd meteorological week (8 WAS) while parasitoid populations peaked (14.50 individuals/five plants) earlier at the 39th week (4 WAS). Correlation analysis showed that aphid abundance was positively associated with temperature (r = 0.86) and parasitoid density (r = 0.71), but negatively correlated with humidity (r = –0.75) and rainfall (r = –0.79). Parasitoid abundance was significantly linked to aphid density but not to weather parameters, indicating a density‑dependent response. These results underscore the importance of integrating crop growth stage, planting configuration, and climatic monitoring into pest management strategies for sustainable okra production.
Biomass in Nigeria: The Present State, Obstacles, and Potential as Alternative Fuel Energy
This study presents a structured review of biomass energy in Nigeria, focusing on its current status, technological pathways, challenges, and future prospects. A systematic search of peer-reviewed literature, reports, and databases was conducted to synthesize evidence on present State of biomass energy potentials in Nigeria, analyse technologies of biomass conversion, and obstacles and future prospects. Nigeria generates approximately 144 million tonnes of biomass annually, with an estimated technical energy potential of about 2.33 EJ. Despite this abundance, biomass utilization remains largely traditional and inefficient. The review identifies key barriers, including technological limitations, weak policy implementation, financial constraints, and environmental concerns. The findings further reveal that advanced conversion technologies such as pyrolysis, gasification, and anaerobic digestion remain underdeveloped in Nigeria. The paper highlights opportunities for sustainable bioenergy development through improved policy support, investment in modern technologies, and integration into national energy strategies. This review contributes by providing a critical synthesis of existing knowledge and identifying research and policy gaps necessary for advancing biomass energy utilization in Nigeria.
Boundary-Mediated Phase Ordering and Collision-Free Dynamics in a Vibro-Impact Multi-Particle System
This study investigates a mechanically realizable vibro-impact system exhibiting collision-free multi-particle motion under boundary-induced excitation. The system consists of identical spherical particles undergoing one-dimensional ballistic motion under gravity and repeated impacts with a structured vibrating boundary. While individual particles obey identical free-flight and restitution laws, experiments reveal the spontaneous emergence of temporally ordered, collision-free motion when multiple particles interact with a common impulsive base. To explain this behavior, a minimal non-smooth dynamical model is formulated using Newtonian mechanics and impact-based boundary conditions. The governing equations define an event-driven discrete impact map advancing the system between successive collisions. Although no explicit inter-particle forces are introduced, collective dynamics arise through boundary-mediated timing regulation. Under bounded excitation, the discrete update preserves temporal separation, suppresses synchronous impacts, and stabilizes staggered impact sequences as attracting configurations. The formulation extends classical single-particle bouncing-ball theory to a multi-particle setting and demonstrates how structured boundary excitation induces phase ordering in non-smooth impact systems. Numerical simulations and controlled laboratory measurements confirm the theoretical predictions. The results provide a dynamical explanation of collision-free behavior in vibro-impact systems and establish a framework for boundary-induced regulation in multi-particle impact dynamics.
Impact of Carbon-based Nanoparticles on Biogas Yield from Anaerobic Co-Digestion of Cow Dung and Yam Peels
The aim of this work is to evaluate the impact of carbon-based nanoparticles on biogas yield from anaerobic co-digestion of cow dung and yam peels. The biomass used for the work include sawdust, cow dung and yam peels. The sawdust was obtained from a saw mill and carbonized in a muffle furnace at 600oC. It was then ground into fine particles using hammer mill. The Nano-sized sample was chemically activated using 0.85 M phosphoric acid at a 1:1 (by weight) ratio of the sample to the dilute acid. The sample was washed with distilled water until a neutral pH of 7 was obtained. It was then dried in an electric oven at a temperature of 80oC for 3 hours to obtain the activated carbon-based nanoparticles (ACBNPs). The ACBNPs was characterized using DLS, SEM-EDS, FTIR, XRD and BET. The DLS show that it has a dominant particle size of 11.89 nm confirming that the sample fall within the nanoscale. The SEM results show that the sample has good morphology with contrasts on the surface while the EDS shows that the atomic concentration of carbon in the sample is 71.22, meaning that the carbonization process was successful. The BET results show it has a specific surface area of 250 m2/g and mesoporous particles with good adsorptive properties. The cow dung was collected from a cattle market while the yam peels were collected from a restaurant, pretreated and put in a paste form. The substrates, cow dung and yam peels, were characterized. Microbial assay on the cow dung showed the presence of the microorganisms that are active in anaerobic digestion. Design of experiment (DOE) was generated (a total of 20 runs) using CCD of the design expert software to evaluate the individual and interactive effects of three factors - time, substrate ratio and nanoparticle concentration. Batch experiments were conducted and the daily biogas yields were measured by downward displacement of water in measuring cylinders. Experimental method was employed to evaluate the performance of the anaerobic digestion process while Response Surface Methodology (RSM) was utilized to model the digestion process. The DOE analysis using Response Surface Methodology (RSM) generated a quadratic model showing the individual and interactive effects of the independent factors on the biogas yield. The maximum value of the biogas yield, as predicted by RSM was 2649.5 ml, while the optimal factors were Time (12 days), Substrates mixing ratio (45% or CD: YP ratio of 9:11) and NPs concentration (164 mg/L). The results demonstrated that the addition of nanoparticles significantly improved biogas and methane yields compared to the control (without nanoparticles). Precisely, the biogas yield increased by 33.2% while the methane content increased by 4.1%. This improvement is attributed to enhanced microbial activity, improved electron transfer, and accelerated degradation of complex organic substrates.
Transient Simulation of a 240/120V Step Down Three-Phase to Five-Phase Transformer for Multiphase Drive Applications
The increasing adoption of five-phase electrical machines in high-reliability and high-performance applications calls for efficient phase conversion from conventional three-phase utilities. Existing solutions predominantly rely on power electronic converters, which sadly introduce switching losses, electromagnetic interference, and increased system complexity. This paper builds on existing approach for developing a passive three-phase to five-phase transformer system with additional step-down functionality and electromagnetic validation. A generalized transformation matrix is derived to synthesize balanced five-phase voltages with 72° phase displacement from a 120° three-phase source. Winding turn relationships are formulated to integrate step-down voltage functionality without compromising phase symmetry. Magnetic circuit analysis by finite element analysis methods are used to evaluate flux distribution. Results demonstrate that balanced five-phase output stepped down from 240V to 120V can be achieved. The core loss obtained for the system is 2.87% with a symmetric flux distribution around the central limb and a flux density in the linear region of the B-H curve. The output voltage has a THD of 7.66%. These findings validate the proposed passive transformer system as a viable alternative for fixed-frequency multiphase applications requiring high reliability and galvanic isolation.
Purification of Oil-Polluted Sea Water using Carbonized Rice Husk Adsorbent Prepared in a Closed Reactor
The study involves purification of oil polluted sea water using carbonized rice husk (CRH) as adsorbent. Carbonization was carried out in a closed reactor. Important properties of the rice husk (RH) and carbonized rice husk (CRH) were determined using standard methods. Six sets of experiments were carried out with initial oil concentration of 1.35 mg/L and CRH dosages of 0, 6.67, 13.33, 20, 26.67, 33.33 g/L, separately to determine the optimal adsorption dosage and percentage of oil removal. Secondly, five sets of experiments were carried out under the adsorption time of 1 h, 2 h, 3 h, 4 h, and 5 h, with the optimal dosage for adsorption determined from the result of the first experiment to determine the optimal adsorption time. Lastly, another five sets of experiments were carried out under the adsorption time of 0 h, 1 h, 3 h, 5 h, and 7 h with the same optimal dosage for adsorption determined from the result of the first experiment to determine the COD removal. The surface area, bulk density, and thermal conductivity of the RH and CRH were respectively 0.78 and 97.4 m2/g, 0.1 and 0.19 g/cm3, and 0.04 and 0.035 W/(m. K). 13.33 g/L was determined as the optimal dosage for adsorption in this study. The oil removed with the optimal dosage was 71.85% at 3 h optimal time, while the total oil removed was 85.01%. The COD removed at this optimal time was 34% while the highest COD removal was 48%. The CRH showed ideal effects in the purification of oil-polluted sea water with excellent adsorption ability for oil in the oil polluted sea water.
Enhancing the Performance of DC Servomotor Based Antenna Position Control System in Satellite Communication Using PID-LQR
In this work, a control system has been designed based on Proportional Integral Derivative (PID) optimized discrete-time Linear Quadratic Regulator (LQR) called PID-LQR and implemented with a DC servomotor-based antenna positioning control system in MATLAB/Simulink environment. The system response was analyzed considering the uncompensated state, the results obtained were presented in terms of steady-state transient response characteristics, which were rise time, peak time, settling time, overshoot, and steady-state error. In the uncompensated state, the rise time was 0.52s, peak time was 1.30s, settling time was 4.35s, overshoot was 34.7%, and steady-state error was 0. Considering the high value of overshoot, a LQR was designed and incorporated into the system to form a closed-loop control system, and simulation conducted revealed that the cycling associated with the uncompensated because of high overshoot (34.7%) was greatly reduced to 6.43% and steady-state error of 0 was achieved. The performance of LQR was further optimized by integrating PID parameter. PID-LQR reduced the rise time from 2.02s to 1.98s, peak time from 4.20s to 3.49s, settling time from 6.11s to 3.94s, and overshoot from 6.43% to 3.80%. These reductions in transient response parameters revealed that the designed PID-LQR yielded the most effective response in terms of stability. This is because the PID-LQR provided most smooth and most stable response compare to other control systems measured against the uncompensated system. Therefore, the use of the PID-LQR provided more stable and reliable tracking for antenna positioning system in satellite dish antenna for deep space application.
Hydrogeophysical assessment of aquifer vulnerability in some parts of Amawbia and its environs, south east, Nigeria
The rapid increase in the population of Amawbia has led to a growing demand for groundwater resources. This increase has necessitated the evaluation of aquifer protective capacity in order to protect it from contamination. The electrical resistivity measurements were used to assess the aquifer protective capacity of Amawbia. Vertical electrical sounding data were collected at four locations and the interpretation was done using Winresist software. The result revealed that the lithology of the area comprised mainly of laterite, clayey sand, shale, dry sand and saturated sand. The longitudinal conductance was computed using the resistivity and thickness values obtained from the interpreted data to evaluate the protective capacity. The protective capacity values ranged from 0.0081 to 1.3486 mhos. The results further revealed that most of the areas investigated are vulnerable to groundwater contamination.