Department of Physical Sciences

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1-Minute Rain Rate Distribution for Communication Link Design Based on Ground and Satellite Measurements in West Africa
(Begell House, Inc., 2020) Sanyaolu, Modupe
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 results 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 from 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 suitable for estimating the 1-minute rain rate statistics required for propagation planning over West Africa.
Acoustic Vibrational Resonance in a Rayleigh-Plesset Bubble Oscillator
(Elsevier, 2020-09-23) Vincent, Uchechukwu
The phenomenon of vibrational resonance (VR) has been investigated in a Rayleigh-Plesset oscillator for a gas bubble oscillating in an incompressible liquid while driven by a dual-frequency force consisting of high-frequency, amplitude-modulated, weak, acoustic waves. The complex equation of the Rayleigh-Plesset bubble oscillator model was expressed as the dynamics of a classical particle in a potential well of the Liénard type, thus allowing us to use both numerical and analytic approaches to investigate the occurrence of VR. We provide clear evidence that an acoustically-driven bubble oscillates in a time-dependent single or double-well potential whose properties are determined by the density of the liquid and its surface tension. We show both theoretically and numerically that, besides the VR effect facilitated by the variation of the parameters on which the high-frequency depends, amplitude modulation, the properties of the liquid in which the gas bubble oscillates contribute significantly to the occurrence of VR. In addition, we discuss the observation of multiple resonances and their origin for the double-well case, as well as their connection to the low frequency, weak, acoustic force field.
Analysis of Rain Fade Durations on Communication Links at Ka Band in Nigeria
(International Journal of Recent Technology and Engineering (IJRTE), 2020) Willoughby, Alexander
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. This study investigates the number of fade events per fade duration interval exceeding attenuation thresholds ranging from 1 dB to 18 dB at 40 GHz. 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 stations, under the Centre for Atmospheric research (CAR), an activity Centre of the National Space Research and Development Agency (NASRDA) in Nigeria, cover the major climatic regions in the sub-Saharan region, namely equatorial, humid tropical and tropical zones (Geo. 4:82 N to 9:58 N). The results show that fade duration decreases as attenuation increases across all the locations. The implication is that heavy rains, causing higher attenuation, occur for shorter time duration. Similarly, higher attenuation depends on raindrops size and rain intensity. Consequently, the frequency of fade events exceeding 1 dB threshold is higher than other thresholds with respect to the fade duration.
Anode Materials for Lithium-based Batteries: A Review
(2020-06-26) Soge, Ayodele
Graphite as a conventional anode material has been unsuccessful in satisfying the requirements of future high-performance lithium-ion batteries due to its low theoretical specific capacity (372 mAh g−1) and low operating potential (~0.1 V). This has resulted in strong demand for new anode materials with high reversible capacity and stable cycling life. Thus, diverse new anode materials have been proposed as a replacement for graphite in recent years. The novel materials reviewed in this study include transition-metal compounds, silicon-based compounds, and carbon-based compounds. The prospects of these materials in developing high-performance lithium-ion batteries for electric vehicles and large-scale energy storage applications are also highlighted.
Assessment of Five Predictive Models for Solar Radiation in Southwest Nigeria
(Nigerian Journal of Environment and Health, 2021) Willoughby, Alexander
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.
Assessment of Musculoskeletal Discomfort among Mini-Bus Drivers in Osun State, Nigeria
(International Journal of Progressive Sciences and Technologies (IJPSAT), 2022) Sanyaolu, Modupe
There have been many reports on the physical factors contributed to the development of work-related musculoskeletal disorders (WMSD) which have a negative influence on the health of employee across different occupations including bus drivers. This study focuses on the assessment of musculoskeletal disorders among mini-bus drivers popularly called “Korope” in the Osun State of Nigeria. This research is based on questionnaires extracted from the standard Nordic questionnaire for the assessment of musculoskeletal disorders (MSDs). The results obtained from the questionnaire showed that the low back, knee and the ankle/feet were found to be the most common areas of discomfort among the population. The elbow showed the least area of musculoskeletal discomfort while the shoulder,upper back, neck, thigh/hips and the wrist/ hands showed moderate discomfort. Some of the subjects experienced at least two of the discomforts.
Atmospheric Aerosol Loading at Ilorin, a Tropical Station
(The African Review of Physics, 2014) Willoughby, Alexander
This work reports the inter-annual variability of the seasonally recurring aerosol haze at Ilorin (8°32¢N, 4°34¢E) a central state of Nigeria, which is in the tropical zone. The data consist of observations collected over a period of seven years 1987 –1990 and 1996 - 1998 using the EKO Sun-photometer model SM –120 with “peak hold” and full view 2.4°quartz window and interference filters having peak transmission at the wavelengths 500, 675, 875 and 945nm, respectively. The data coverage presents to us five distinct aerosol seasons viz: 1987/88, 1988/89, 1989/90, 1996/97 and 1997/98. The data collected for all the aerosol seasons were compared wavelength-by-wavelength and month-by-month. Although the regional mean Aerosol Optical Depth (AOD) and Precipitable Water (PW) remains essentially constant in trend for all the data years, they vary from year to year with spread ranging from 0.789 to 1.526 for AOD1, 0.808 to 1.50 for AOD2, 0.814 to 1.178 for AOD3, and 0.340 to 1.480 for the PW. The coefficient of variation determined is between 27.4 and 52.0 for AOD1, 23.9 and 53.2 for AOD2, 25.2 and 52.8 for AOD3 and 12.9 and 39.5 for PW. The Angstrom exponent was also found to vary from about 0.2 to 3.8.
Cathode Materials for Lithium-ion Batteries: A Brief Review
(Journal of New Materials for Electrochemical Systems, 2021-10) Willoughby, Alexander
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.
Chaos Synchronization Based on Linear and Adaptive Controls: Theory and Experiment
(2021-10-30) Vincent, Uchechukwu
In this paper, we report on the theoretical and experimental investigation of chaotic synchronization using of a single-variable linear feedback and adaptive controllers. Based on the Lyapunov stability theory, theoretical approaches to the design of controls are presented, and the results are validated numerically and by employing electronic circuit experiments. We used two typical oscillators, namely, the Lorenz and Sprott chaotic systems to demonstrate our results; while off-the-shelf components on breadboard were used to experimentally implement the proposed single variable controllers. We specifically show that synchronization of two chaotic systems can be experimentally realized when the strength of the feedback exceeds a theoretically determined threshold
Characteristics of Rain Fade Slope on Microwave Communication in Mowe, Nigeria
(IOP Publishing, 2021) Sanyaolu, Modupe
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.
Characteristics of Rain Fade Slopes on Microwave Communication in Mowe
(Journal of Physics Conference Series, 2021) Akinyemi, Gbenga
Characteristics of Rain Fade Slopes on Microwave Communication in Mowe, Nigeria
(Journal of Physics: Conference Series PAPER, 2021) Willoughby, Alexander
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 secondorder 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.
Controls on the compositional framework and petrogenesis of Early Cretaceous first cycle quartzose sandstone, North Gondwana
(Elsevier, 2021-09-10) Adepehin, Ekundayo Joseph
Recent advances in sedimentary research have shown that quartz sandstones are scarce in the global geologic record and prolonged sediment transport does not automatically produce mineralogically mature sediments. Published data are based mainly on Cambro-Ordovician arenites. This paper discusses the formational controls of early Cretaceous syn-rift quartzose from northern Gondwana based on integrated petrographic, mineralogic, and electrofacies proxies on the Upper Sarir Sandstone Formation, Sirte Basin, Libya. The study aimed to understand the compositional framework and construe the sedimentological processes that produced the quartz-rich sandstones. Acquired samples (n=40) from three boreholes (N8-97, N7-97, and N4-97)were subjected to petrographic analysis, x-ray diffractometry, and variable pressure scanning electron microscopy with energy dispersive x-ray spectrometry. Qualitative and quantitative datasets indicate that the mean framework composition (Q97F0L3) of the sample is quartz-dominated and primarily detrital, although diagenetic imprints, mostly quartz cementation, quartz overgrowth, and other authigenic precipitates, are present. Evidenced by the predomination f monocrystalline quartz grains (99.10%) over the polycrystalline type (0.90%), the dominance of nonundulatory extinction (72.50%), and noticeable euhedral crystals, the compositional framework of the studied quartzose reflects a predominant plutonic provenance with some metamorphic inputs. The possibility of significant sediment reworking is ruled out based on short to moderate transport distance (~100 km) interpreted from the interplay of textural parameters, depositional model, and paleogeography. A humid paleoclimate alongside its associated rigorous chemical weathering is constrained as the dominant control in the formation of the Upper Sarir quartzose sandstone from a dominant craton interior provenance. These conditions probably produced other early Cretaceous arenitic sandstones in other reaches of North Gondwanaland.
A Cost Effective Solar Charge Controller and Load Driver for DC Home Appliances
(IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE), 2015-10) Willoughby, Alexander
Design and Construction of Ultraviolet and Incoming Solar Irradiance Sensing Device
(Walailak Journal of Science and Technology, 2021-08-02) Willoughby, Alexander
In-situ measurements of ultraviolet (UV) and solar irradiance is very sparse in Nigeria because of cost, and most researchers estimate them using meteorological parameters. In this work, a low-cost UV and pyranometer device, using locally sourced materials, was developed. The instrument consists of a UV sensor (ML8511), a photodiode (BPW34) housed in a carefully sealed vacuumed glass bulb, the UV and solar irradiance sensor amplifiers, a 16-bit analog-to-digital converter (ADS1115), Arduino mega 2560, liquid crystal display (LCD) and microSD card for data logging. The designed amplifier has an offset voltage of 0.8676 mV. The sensitivity of the irradiance device is 86.819 Wm-2/mV with a correcting factor of 27.77 Wm-2 and a maximum range of 1200 Wm-2. The instrument validation error is 9.67% and a correlation coefficient of 0.89 when compared with a standard SRS100 pyranometer. The UV sensor showed a close response with a correlation of 0.99 in comparison with a standard Skye instrument. From 08:00 to 16:00 local time (LT), there is a very close agreement between the standard device and the developed counterpart, with marginal differences of about 9.6% observed at the two extremes.
Detection of Wood Decay and Cavities in Living Trees: A Review
(Canadian Science Publishing, 2020-11) Soge, Ayodele
It has been established that wood decay and cavities in tree stems contribute significantly to tree failures. Several techniques have been reported by researchers for detecting wood decay and cavities in living trees. These techniques are reviewed in this study under two broad categories: invasive and noninvasive methods. The invasive methods include traditional (decay detecting drill, increment borer, and boroscope), radiographic, acoustic, and electrical resistivity techniques. The noninvasive methods comprise microwave scanning, magnetic resonance imaging, X-ray tomography, and traditional techniques involving the use of mallets. Two or more methods are usually combined to investigate the health status of a tree for comparison and validation of results. The prospects and challenges of the various techniques in diagnosing wood decay, cavities, and other structural defects in living trees are reported. This review aims to help researchers in this field identify areas of further work towards the efficient monitoring and management of forest and urban trees.
Development of a Low-Cost Pyrometer using Locally Sourced Materials
(International Journal for Scientific Research & Development, 2019) Osinowo, Muritala
Measurement of solar irradiance in-situ was very scanty in this part the world most research estimate using atmospheric weather parameter. In this work a low-cost pyranometer using locally sourced materials was developed. Instrument or device consists of photodiode (BPW34) housed inside 40 with bulb that is perfectly seal, solar irradiance sensor amplifier, 16-bit analog-to-digital converter (ADS1115), arduino mega2560, and liquid crystal display (LCD) and microSD card shield. The design amplifier has offsetting voltage of 0.8676 mV. The sensitivity of solar irradiance was amplifier 868.19 Wm-2V-1 with correct factor 27.77 Wm-2. The output range of developed instrument is between 0.1 mV to 1.4 V with maximum 1200 Wm-2. The possible error of the instrument is 9.67%. The result obtained when compared SRS100 pyranometer is 0.89. The result obtained from collected data shows that from 8.15 to 16.00, local time, the response was very good with little difference at early hour of day around up to 8.30 am and around 4.30 pm downward.
Development of a Low-Cost Soil Heat Flux and Temperature Profile with Logger
(International Journal of Advances in Scientific Research and Engineering, 2019-07-26) Osinowo, Muritala
Variation of soil temperature and soil heat flux measurements from a locally fabricated and calibrated device were analyzed and compared with a standard device. The soil heat flux consists of two-disc aluminum plates, dielectric material and two thermocouples such that each thermocouple was sandwiched between the aluminum plates and one side of the dielectric material. The sizes of the aluminum plates and the dielectric material were 32 mm in diameter and their thickness is 2.5 mm. Differential temperature between two thermocouples attached to two aluminum plates separated by a thermal insulator was used to measure the soil heat flux values. The thermocouples amplifier module AD8495 and then combined with a 16-bit Analog to Digital Converter (ADS1115) for a good measurement resolution was employed for the signal conditioning. A semiconductor sensor DS18B20 was used to measure the soil temperature. The microSD shield was included for storing data and DS3232, a Real Time Clock (RTC) module for timekeeping. Arduino mega 2560 microcontroller was used to coordinate the whole active and display the activities on LCD. The soil heat flux sensor was calibrated using the principle of thermal conduction over the surface area by heating with a known heat source. The thermal conductivity of heat flux is given by 3.3407 (WV-1m-1) from the empirical deduction. The temperature sensing unit was checked for accuracy by inserting it inside a calorimeter with the mercury-in-glass thermometer and the correlation obtained was 0.92. The soil heat flux and temperature sensing unit were compared with that of standard Campbell device. The correlation obtained for soil heat flux and temperature were 0.89 and 0.95 respectively. The result obtained when installed at the Redeemer’s University, Ede, Nigeria, the variation of soil heat flux and temperature when placed at the same level of 10 cm into the soil gave the same value. The maximum peak of heat flux density usually occurs at about 13:00 pm to 15:00 pm with values around 260 W/m2 at 10 cm. The logging interval can be preset to any rate from 30 seconds and above.
Development of an Electronic Load I-V Curve Tracer to Investigate the Impact of Harmattan Aerosol Loading on PV Module pern2tkformance in Southwest Nigeria
(Solar Energy, 2018) Willoughby, Alexander
in Southwest Nigeria. To this end, a simple, open-source, cost effective electronic load I-V curve tracer was developed to compare the I-V characteristics of a pair of horizontally positioned 80W monocrystalline modules for the duration of the Harmattan period. The control module was regularly cleaned manually and the other module left to accumulate the Harmattan dust deposits. In order to obtain the modules’ characteristic parameters, an Arduino-based pulse width modulation (pwm) duty cycle was implemented to vary simultaneously, the gate-source voltages, VGS, of two power metal-oxide semiconductor field-effect transistors (MOSFETs) acting as fast variable loads for the modules. Experimental results acquired from the prototype circuit demonstrate that this method provides a more accurate approach and faster response than the resistive load tracer method. The prototype instrument was able to measure and reproduce characteristic curves that are obtainable from the more expensive branded products. Resulting curves depict reduction in the short circuit current, ISC, the current at maximum power, IMP, the power output, PMP and the efficiency, η of the dusty module by more than 18% in comparison with the control module over the measurement period.
Development of an Electronic Load IV Curve Tracer to Investigate the Impact of Harmattan Aerosol Loading on PV Module Pern2tkformance in Southwest Nigeria
(Solar Energy, 2018-05-05) Osinowo, Muritala
This study investigates the impact of the seasonal Harmattan aerosol loading on PV module efficiency at a station in Southwest Nigeria. To this end, a simple, open-source, cost effective electronic load I-V curve tracer was developed to compare the I-V characteristics of a pair of horizontally positioned 80W monocrystalline modules for the duration of the Harmattan period. The control module was regularly cleaned manually and the other module left to accumulate the Harmattan dust deposits. In order to obtain the modules’ characteristic parameters, an Arduino-based pulse width modulation (pwm) duty cycle was implemented to vary simultaneously, the gate-source voltages, VGS, of two power metal-oxide semiconductor field-effect transistors (MOSFETs) acting as fast variable loads for the modules. Experimental results acquired from the prototype circuit demonstrate that this method provides a more accurate approach and faster response than the resistive load tracer method. The prototype instrument was able to measure and reproduce characteristic curves that are obtainable from the more expensive branded products. Resulting curves depict reduction in the short circuit current, ISC, the current at maximum power, IMP, the power output, PMP and the efficiency, η of the dusty module by more than 18% in comparison with the control module over the measurement period.

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