Department of Electrical and Electronic Engineering

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1-Minute Rain Rate Distribution for Communication Link Design Based on Ground and Satellite Measurements in West Africa
(Begell Journal, 2020) Dairo, Oluropo
West Africa is in the tropical region and it is characterized by intense rainfall. Rain is a significant factor causing signal degradation on microwave links due to its variability; it causes scattering, absorption, and refraction of electromagnetic waves. Experimental studies have shown that rainfall intensities above 64 mm/h at 0.01% in this region result in noticeable digital television signal fading, squelching and complete outages. Hence the need for estimating rain rate distribution across West Africa. This paper analyzed the rain rate in six countries in West Africa, namely Benin, Cameroon, Cote d'Ivoire, Ghana, Nigeria, and Togo. Three locations were selected in each country. Rain data were obtained from the Tropical Rain Measuring Mission-Precipitation Radar (TRMM-PR) and the Global Precipitation Measurement (GPM) missions, and Tropospheric Data Acquisition Network (TRODAN) weather stations in Nigeria. This study used ITU-R and Moupfouma models for the conversion of the 5-minute rain rate to 1-minute integration time at a probability of exceedance ranging from 1% to 0.001%. The cumulative rain rate distribution from the measured rain rate is presented alongside the predictions of the models. ITU-R and Moupfouma predicted similar results at 0.1% probability of exceedance. ITU-R overestimates the rain rate above 0.01% probability of exceedance. On the other hand, the Moupfouma models prediction plots at 0.01% overlap for all locations, indicating that there will be a signal loss at 0.01% probability of exceedance across these locations. The result shows that the 5- minute conversion provides satisfactory performance and is suitable for estimating the 1-minute rain rate statistics required for propagation planning over West Africa.
a-Amylase inhibition, anti-glycation property and characterization of the binding interaction of citric acid with a-amylase using multiple spectroscopic, kinetics and molecular docking approaches
(Elsevier, 2022-05) Dairo, Oluropo
The quest to suppress complications associated with diabetes mellitus is ever increasing, while food addi- tives and preservatives are currently being considered to play additional roles besides their uses in food enhancement and preservation. In the present study, the protective prowess of a common food preserva- tive (citric acid, CA) against advanced glycation end-products (AGEs) formation and its binding interac- tion mechanism with a-amylase (AMY), an enzyme linked with hyperglycemia management, were examined. Enzyme inhibition kinetics, intrinsic fluorescence, synchronous and 3D fluorescence spectro- scopies, ultraviolet–visible (UV–Vis) absorption spectroscopy, Fourier transform-infrared (FT-IR) spec- troscopy, thermodynamics, and molecular docking analyses were employed. Results obtained showed that citric acid decreased a-amylase activity via mixed inhibition (IC50 = 5.01 ± 0.87 mM, Kic = 2.42 mM, Kiu = 160.34 mM) and suppressed AGEs formation (IC50 = 0.795 ± 0.001 mM). The intrinsic fluorescence of free a-amylase was quenched via static mechanism with high bimolecular quenching constant (Kq) and binding constant (Ka) values. Analysis of thermodynamic properties revealed that AMY-CA complex was spontaneously formed (DG < 0), entropy driven (TDS > DH), with involvement of electrostatic forces. UV–Vis, FT-IR and 3D fluorescence spectroscopies affirmed alterations in a- amylase native conformation due to CA binding interaction. CA interacted with His-101, Asp-197, His- 299, and Glu-233 within AMY active site. Our findings indicated that CA could impair formation of AGEs and interact with a-amylase to slow down starch hydrolysis; vital properties in management of type 2 diabetes complications.
Adaptive Network Based Fuzzy Inference System Model for Minimizing Handover Failure in Mobile Networks
(International Journal of Innovative Science and Research Technology, 2017-09) Orimogunje, Abidemi
For seamless connection between mobile users on the same and different mobile technologies there is need for the deployment of a more complex algorithm for a successful switching of mobile users. Signal to interference ratio, speed of the mobile users and traffic distance are the three input used in the Adaptive network based Fuzzy inference system (ANFIS) which is an hybrid of two techniques of artificial intelligence which make it suitable to handle complexities such as ping-pong effect and interference which impair on the quality of service (QoS) during call handover process as the mobile users move from one coverage area (cell) to another.
Advanced Digital Laboratory: an FPGA-Based Remote Laboratory for Teaching Digital Electronics
(American Society for Engineering Education, 2009, 2009-06) Osasona, Oladipo
The experimentation component of most Science and Engineering curricula in Nigeria is inadequate. In Obafemi Awolowo University for example, undergraduate students typically carry out around five assignments related to digital electronics, and there is no treatment whatsoever of Field Programmable Gate Arrays(FPGAs). In the research work being reported, an attempt has been made to develop a remote laboratory though which the number of digital electronics experiments students carry out can be increased. The remote laboratory, called the Advanced Digital Lab (ADLab), allows students to synthesis digital systems on an FPGA with a hardware description language. To achieve this, a development board with an Altera Cyclone II FPGA is connected to a computer implementing the server tier of the iLab batched architecture. The client through which the remote student interacts with the ADLab is implemented with Java, which allows for a reasonable amount of platform independence. This paper discusses the software and hardware aspects of the ADLab architecture and gives some insight into some design decisions. The paper also reports that the system is being tested at Obafemi Awolowo University and that student feedback so far indicates high student satisfaction with the remote laboratory.
ARDUINO-BASED MAXIMUM POWER POINT TRACKING CHARGE CONTROLLER USING PERTURB & OBSERVE AND CONSTANT-VOLTAGE ALGORITHMS
(Begell House, Inc. www.begellhouse.com, 2023) Ilori, A. O.; Dairo, O. F.; Willoughby, A. A.; Osinowo, M. O.; Ewetumo, T.
The output power delivered by a photovoltaic (PV) module to charge a battery is dependent on solar radiation incident upon it and the ambient temperature. To reduce PV energy loss, the PV panel is kept at peak efficiency by operating the PV system at the maximum power point (MPP) to deliver maximum power to the battery under charge. In this work, Perturb & Observe (P&O) algorithm was implemented in conjunction with constant voltage (CV), using the MATLAB/Simulink tool. Results obtained from these simulations show that the tracking efficiency of the P&O algorithm decreases with solar irradiation. However, the relatively good performance of the CV algorithm at low irradiation levels augments the P&O method. Both algorithms were implemented in a maximum power point tracking (MPPT) design using an ATMega328 microcontroller operating on a minimal Arduino-compatible integrated development environment (IDE) prototype circuit.
Assessment of Five Predictive Models for Solar Radiation in Southwest Nigeria
(LivingScience Foundation, 2020-10) Dairo, Oluropo
This study compares the accuracies of five predictive models for estimating solar radiation amongst other meteorological parameters in Southwest Nigeria. Twenty-one years of monthly averages of six measured meteorological parameters obtained from six stations in southwest Nigeria have been subjected to five mathematical models for prediction purposes. Solar radiation and sunshine hours have been modelled using the sum of two-Gaussians, the sum of two-Lorentzians, Fourier on four harmonics, sine wave and fourth-order polynomial functions. The fitting accuracies of these models were tested using performance indicators; mean bias error (MBE), root mean square error (RMSE), mean percentage error (MPE), standard error (SE) and the correlation coefficient (R). An evaluation of the models showed that the Gaussian and Lorentzian models are in good agreement with the observed data. However, the Fourier on the fourth harmonics model had the lowest MBE, RMSE and MPE, consequently highest correlation coefficient values, indicating high model accuracy. Thus, the Fourier model has the best correlation with the observed data and is recommended for estimating these variables in the selected locations.
Cathode Materials for Lithium-ion Batteries: A brief review
(International Information and Engineering Technology Association (IIETA), 2021) Dairo, Oluropo
Layered lithium cobalt oxide (LiCoO2) as a pioneer commercial cathode for lithium-ion batteries (LIBs) is unsuitable for the next generation of LIBs, which require high energy density, good rate performance, improved safety, low cost, and environmental friendliness. LiCoO2 suffers from structural instability at a high level of delithiation and performance degradation when overcharged. Besides, cobalt, a significant constituent of LiCoO2 is more costly and less environmentally friendly than other transition metals. Therefore, alternative cathode materials are being explored to replace LiCoO2 as cathode materials for high-performance LIBs. These new cathode materials, including lithiated transition metal oxides, vanadium pentoxides, and polyanion-type materials, are reviewed in this study. The various challenges hampering the full integration of these cathode materials in commercial LIBs and viable solutions are emphasised.
Characteristics of rain fade slopes on microwave communication in Mowe, Nigeria
(IOP Publishing, 2021) Dairo, Oluropo
In this paper, the rain fade characteristics at Ka-band (30 GHz) in Mowe (Lat 6.80o N, Lon 3.40o E) Nigeria have been presented. The analysis includes both the first- and second- order statistics of rain rate and rain attenuation, and fade duration and fade slope, respectively. Both parameters are useful for planning the point-to-point microwave link for various communication feeder networks. The estimated fade duration and the fade slope were compared with the ITU-R P.837-5 model. The results of this study would be valuable for improving rain fade mitigation techniques in Nigeria.
Development of an Operational Amplifier Virtual Laboratory based on iLab Architecture and NI ELVIS
(American Society for Engineering Education, 2008) Osasona, Oladipo
We have developed and deployed ‘OpAmp Lab’, a pedagogic operational amplifier virtual laboratory based on the MIT iLab architecture. The architecture is a three-tier architecture that abstracts the various parts of a remote laboratory system into different functional domains. This architecture makes the new virtual Lab experiments scalable and reduces the development and deployment time of new experiments through component reuse. OpAmp Lab uses the National Instrument ELVIS hardware platform for experimental set-up. Basic Op-amp circuits are realized through reconfigurable Dozen Impedance Op-amp configuration mounted on a multimode switch array. The front end or Client is implemented as a Winform Client, written in C# and uses connectible nodes as a metaphor for back-end hardware configuration. Strong emphasis is placed on the realism of the user interface, as we argue, the user interface is the most important determinant of the quality of a user’s educational experience. We discuss the various components of OpAmp Lab and the lessons learnt in the development of the system as well as the development of pedagogical experiments developed for it. OpAmp Lab has been in use at Obafemi Awolowo University, NIGERIA for the last two years. Faculty and students response has been strongly positive. We provide data showing that the Lab offers a viable means of augmenting the laboratory component of electrical engineering curricula in developing countries.
Development of Ultra Low-Cost Data Acquisition System (DAS) for Developing Countries
(Walailak University, 2022-07-01) Dairo, Oluropo
The Data Acquisition System (DAS) is an important equipment in measurement systems, especially in weather monitoring and also very crucial in many areas such as agricultural, communication, transportation, sport and industrial processes. This work proposes a weather monitoring system based on an Arduino Mega 2560 microcontroller board. The microcontroller has the ability to monitor, record and display the information of atmospheric sensor parameters connected to its analogue and digital pins. The outputs of analogue sensors are connected to the microcontroller through separate ADC for sampling. An LCD attached to the microcontroller displays the measured parameters. For analysis, the data is stored in excel format and can be copied directly from a microSD card. The DAS was tested and examined through intensive experimental work. From the tables and plots obtained from the experiment for standardizing the sensors, it is clear that there is close conformity between the data collected by the developed system and the existing standard systems. The need for extra cost baud rate and expensive third-party computer software for interfacing to download data from the logger has been eliminated. There is no need for the internet for any linking or configuration. It is evident that the DAS is of better choice in terms of cost and maintenance. The system will be helpful in monitoring and recording atmospheric parameters.
Developmentof a Propagation Model for IEEE 802.11 Wireless Networks: Case of GidanKwano Campus, FUT MINNA
(Ahmadu Bello University Zaria Proceedings of the 1st National Communication Engineering Conference 2018, 2018-10-18) Ogunjide, Sunday
Wireless propagation modeling is an essential task in planning wireless networks. In the last few decades, the use of Wireless Local Area Network (WLAN) popularly referred to as Wi-Fi(Wireless Fidelity) in communication system has been on the increase with the exponential usage of handheld cell phones, laptops, and palm-tops to mention but a few. Notwithstanding, WLAN faces a peculiar propagation issue which lies in its changing propagation environment and this affects the quality of service. Poor quality of service is experienced on WLAN of GidanKwano campus of Federal university of technology, Minna. This arises due to signal propagation impairment caused by the terrain and the structures within the campus. Received Signal Strength (RSS) measurements were conducted at different locations away from the selected Access Points (APs) both in Line of Sight (LOS) and Non- Line of Sight (NLOS) situations. The path loss exponent (n) and standard deviation (σ) were estimated for the environment. The obtained results were contrasted with the already published work to show the level of agreement. The empirical models were developed for LOS and NLOS situations and compared with the existing standard models.
Estimation of Rain Fade Durations on Communication Links at Ka Band in Equatorial and Tropical Regions
(Begell Journal, 2020) Dairo, Oluropo
Duration of rain fade events is a major parameter to be considered when designing a communication link. Fading is a phenomenon responsible for intermittent fluctuations of radio signals observed in the tropical region. The prevalence of rain in the tropics accounts for the frequency of fading observed in this region. Despite, the efforts of researchers to help systems designers give due consideration to fade mitigation techniques in other parts of the world, there is still a dearth of fade duration data from the African equatorial and tropical regions. Hence, this study estimates the number of fade events per fade duration interval exceeding attenuation thresholds ranging from 1 dB to 18 dB at ka-Band (26.5 GHz−40 GHz), leading to nonavailability of satellite systems during raining events in the African equatorial regions. The range of fade durations is from 10 s to 5000 s. The International Telecommunication Union (ITU-RP) propagation model and data from the Tropospheric Data Acquisition Network (TRODAN) were used for the analysis. The eight TRODAN observatories, under the Centre for Atmospheric Research (CAR), cover the major climatic regions in the sub-Saharan region, namely equatorial, humid tropical and tropical zones (Geo. 4.82єN to 9.58єN). Fade duration decreases latitudinally as the attenuation threshold increases from low to higher latitudes. The equatorial region suffers the highest frequency of fade events while the tropical zones recorded the lowest. In addition, the 10 s fade duration recorded the highest occurrence of fade events. The implication is that heavy rains, causing higher attenuation, occur for a shorter time duration. Similarly, higher attenuation depends on raindrops' size and rain intensity. Consequently, the number of fade events exceeding 1 dB threshold is higher than other thresholds with respect to the fade duration.
Exploring the binding interactions of structurally diverse dichalcogenoimidodiphosphinate ligands with α-amylase: Spectroscopic approach coupled with molecular docking
(Elsevier, 2020) Dairo, Oluropo
Postprandial hyperglycemia has orchestrated untimely death among diabetic patients over the decades and regulation of α-amylase activity is now becoming a promising management option for type 2 diabetes. The present study investigated the binding interactions of three structurally diverse dichalcogenoimidodiphosphinate ligands with α-amylase to ascertain the affinity of the ligands for α-amylase using spectroscopic and molecular docking methods. The ligands were characterized using 1H and 31P NMR spectroscopy and CHN analysis. Dis- elenoimidodiphosphinate ligand (DY300), dithioimidodiphosphinate ligand (DY301), and thio- selenoimidodiphosphinate ligand (DY302) quenched the intrinsic fluorescence intensity of α-amylase via a static quenching mechanism with bimolecular quenching constant (Kq) values in the order of x1011 M-1s-1, indicating formation of enzyme-ligand complexes. A binding stoichiometry of n≈1 was observed for α-amylase, with high binding constants (Ka). α-Amylase inhibition was as follow: Acarbose>DY301>DY300>DY302. Values of thermodynamic parameters obtained at temperatures investigated (298, 304 and 310 K) revealed spontaneous complex formation (ΔG<0) between the ligands and α-amylase; the main driving forces were hydrophobic in- teractions (with DY300, DY301, except DY302). UV–visible spectroscopy and Fo ̈rster resonance energy transfer (FRET) affirmed change in enzyme conformation and binding occurrence. Molecular docking revealed ligands interaction with α-amylase via some key catalytic site amino acid residues (Asp197, Glu233 and Asp300). DY301 perhaps showed highest α-amylase inhibition (IC50, 268.11 ± 0.74 μM) due to its moderately high affinity and composition of two sulphide bonds unlike the others. This study might provide theoretical basis for development of novel α-amylase inhibitors from dichalcogenoimidodiphosphinate ligands for management of postprandial hyperglycemia.
Fabrication and Characterization of a Dye-Sensitized Solar Cell using Natural Dye Extract of Rosella (Hibiscus sabdariffa L.) as Photosensitizer
(Nigerian Society of Physical Sciences, 2021) Dairo, Oluropo
The relatively low energy conversion efficiency of dye-sensitized solar cells (DSSCs) is a key challenge hindering the commercialization of the solar cell. The photochemical performance of the dye used as a photosensitizer for the DSSC greatly determines the efficiency of the solar cell. This study demonstrates the suitability of dye extracted from rosella (Hibiscus sabdariffa L.) flowers as a photosensitizer for a DSSC. The natural dye was extracted using the acid water extraction method and was characterized using FTIR spectroscopy and UV–vis spectrophotometry. The absorption spectra of the dye were examined to determine the aptness of the dye as a photosensitizer in DSSCs. The IR absorption spectra of the extracted dye confirmed both amine and hydroxyl compounds as functional groups in the natural dye, which established the suitability of the dye as a photosensitizer in DSSCs. The UV-vis absorption spectra of the natural dye within the visible region illustrate that the aqueous extract from rosella flowers has stable absorption of visible light, thus validating the natural dye as a good candidate for photosensitizer in a DSSC. The fabricated DSSC delivered a short-circuit current of 5 μA and an open-circuit voltage of 0.637 V.
Handover in Mobile Wireless Communication Network - A Review
(International Journal of Advanced Engineering, Management and Science (IJAEMS), 2017-09) Orimogunje, Abidemi
Mobility is the characteristics of mobile communication that makes it irresistible by all and sundry. The whole world is now engaging in wireless communication as it provides users' ability to communicate on-the-go. This is achieved by transferring users from a radio network to another. This process is called handover. Handover occurs either by cell crossing or by deterioration in signal quality of the current channel. The continuation of an active call is a critical characteristic in cellular systems. Brief overview of handover, handover type, commonly used handover parameters, some methods employed in the literature and we present the convergent point for furtherance in the area of mobile wireless communication Handover
Implementing Remote Laboratories with the ILAB Architecture: Three Case Studies from Obafemi Awolowo University, Nigeria
(Computers in Education Journal, 2012-03) Osasona, Oladipo
A number of remote labs based on the iLabs Architecture have been developed and used for credit awarding courses in Obafemi Awolowo University (OAU), Nigeria. These include the Op-Amp iLab, Logic Design iLab, and Robotic Arm iLab. The Op-Amp Lab allows students to access a small operational amplifier circuit hosted in OAU, and with the aid of switching matrices, reconfigure the circuit, inject waveforms, and see the resulting output signals. The Logic Design Lab is built around a Field Programmable Gate Array (FPGA) chip that students can reprogram from afar using the VHDL, a hardware description language. The Robotic Arm iLab is a control engineering laboratory in which students can remotely control a robotic arm located in OAU. Video feedback through BroadCam Video Streaming Server and Livestream (www.livestream.com) allows users observe and measure the robotic arm’s response to their commands. In our paper, we describe the iLab Batched and Interactive architectures and describe three iLabs developed in OAU in detail. Emphasis is placed on technical details and design choices made in developing these labs. We also discuss other aspects of iLab development and use and dwell on issues that could hinder or accelerate the adoption of remote laboratories in developing countries.
Performance Analysis of Temperature Models for Environmental Monitoring in Southwest Nigeria
(LivingScience Foundation, 2019) Dairo, Oluropo
Temperature is a major meteorological parameter driving most of the atmospheric processes vis-a`-vis climate change. Therefore, a consistent model is necessary to achieve sustainable development goal 13 (SDG 13) known as climate action. Long-term monthly averages of surface temperature obtained from six southwest states in Nigeria were subjected to five mathematical models, namely the sum of two-Gaussians, the sum of two-Lorentzians, Fourier on four harmonics, Sine wave and Fourth-order polynomial functions. Statistical tools were used to examine the accuracy and fitness of the models. The evaluation showed that the Gaussian and Lorentzian models are good fits for the observed data. Furthermore, the performance indicators such as mean bias error (MBE), root mean square error (RMSE) and mean percentage error (MPE) recorded the lowest values for Fourier on the fourth harmonic model. Similarly, its correlation coefficient, R, was the highest ranging from 0.95 to 1. Consequently, the Fourier model presented the best correlation with the observed data and hence was recommended for predicting the temperature at the selected locations.
Performance Evaluation of Rainfall Models and Associated Precipitation Oscillations in the Southwestern Climate System of Nigeria
(LivingScience Foundation, 2020-10) Dairo, Oluropo
The study explored the spatio-temporal evolution of rainfall and precipitable water oscillations using data of over two decades. The monthly averages of rainfall and precipitable water were obtained from six locations in the southwestern climatic region of Nigeria. The data were analysed using five mathematical models namely the sum of two-Gaussians, the sum of two-Lorentzian, Fourier on four harmonics, sine wave and fourth-order polynomial functions for prediction purposes. The performances of these models were evaluated using the mean bias error (MBE), root mean square error (RMSE), mean percentage error (MPE), standard error (SE) and the correlation coefficient (R). The performance indicators of the models showed that the Gaussian and Lorentzian models are in good agreement with the observed data. However, the Fourier on fourth harmonics model had the lowest MBE, RMSE and MPE, consequently highest correlation coefficient values, indicating high model accuracy. Thus, the Fourier model has the best correlation with the observed data and is recommended for estimating these variables in the selected locations.
Polymer Optical Fibre in Communications and Environmental Monitoring
(URSI Nigeria, 2010-12) Dairo, Oluropo
This paper focuses on niche applications of polymer optical fibre (POF) in modern communication systems and other related areas. The electromagnetic isolation of POF and its relatively high sensitivity compared to conventional sensors has earned it a centre stage in sensing technology. The ability to detect and measure physical parameters such as temperature, humidity and wind speed makes POF suitable for real-time monitoring of environmental and climatic conditions. Other attractive features of POF include a lower cost compared with glass optical fibres, better fracture resistance and flexibility.
Prediction of Rain-Induced Attenuation along Earth-Space Links at Millimeter Wave Bands over West African Region
(Begell Journal, 2021) Dairo, Oluropo
The present work characterizes the degree of rain-induced attenuation on 15-80 GHz earth-space communication links. Eutelsats 36B and 36C, and NigComSat-1R satellite links over five West African countries were considered through the International Telecommunication Union Radiocommunication Sector (ITU-R) [International Telecommunications Union (ITU)], Bryant, and Syjatogor rain attenuation models. Three locations were selected in each country for the analysis using 2013-2017 rain data obtained from the Global Precipitation Measurement (GPM) missions. ITU-R predicted higher attenuation values than the other two models; while Svjatogor values were close to ITU-R, and the Bryant model predicted the lowest. At 99.99% signal availability, rain attenuation along the earth-space link over the five countries ranged between 22.1 and 34.2 dB for Ku-band (15 GHz) but exceeded the satellites' link margins at Ka-band (30 GHz). At 0.1% unavailability, the range is 6-21 dB across all the locations for V-band (60 GHz), which implies that the satellites can sustain 99.9% of signal availability across the countries. However, for 99.99% and 99.9% signal availability at W-band, earth-space links can experience a total outage across the selected stations. Some locations in the northern parts can have 99% availability, which is an ~ 87 h/yr outage. Hence, the result could be a benchmark for planning trans-horizon radio communication links across West Africa.

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