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Item Parameter Estimation of Cellular Communication Systems Models in Computational MATLAB Environment: A Systematic Solver-based Numerical Optimization Approaches(I. J. Computer Network and Information Security, 2024-06-08) Isabona, Joseph; Akinwumi, Sayo A.; Arijaje, Theophilus E.; Ituabhor, Odesanya; Imoize, Agbotiname LuckyModel-based parameter estimation, identification, and optimisation play a dominant role in many aspects of physical and operational processes in applied sciences, engineering, and other related disciplines. The intricate task involves engaging and fitting the most appropriate parametric model with nonlinear or linear features to experimental field datasets priori to selecting the best optimisation algorithm with the best configuration. Thus, the task is usually geared towards solving a clear optimsation problem. In this paper, a systematic-stepwise approach has been employed to review and benchmark six numerical-based optimization algorithms in MATLAB computational Environment. The algorithms include the Gradient Descent (GRA), Levenberg-Marguardt (LEM), Quasi-Newton (QAN), Gauss-Newton (GUN), Nelda-Meald (NEM), and Trust-Region-Dogleg (TRD). This has been accomplished by engaging them to solve an intricate radio frequency propagation modelling and parametric estimation in connection with practical spatial signal data. The spatial signal data were obtained via real-time field drive test conducted around six eNodeBs transmitters, with case studies taken from different terrains where 4G LTE transmitters are operational. Accordingly, three criteria in connection with rate of convergence Results show that the approximate hessian-based QAN algorithm, followed by the LEM algorithm yielded the best results in optimizing and estimating the RF propagation models parameters. The resultant approach and output of this paper will be of countless assets in assisting the end-users to select the most preferable optimization algorithm to handle their respective intricate problems.Item Improving cycling performance and high rate capability of LiNi0.5 Mn0.3 Co0.2 O2 cathode materials by sol-gel combustion synthesis(Journal of Physics and Chemistry of Solids, Volume 196, 2025-01) Ehi-Eromosele, Cyril O.; Liu, Xinying; Mathe, Mkhulu K.The layered LiNi0.5 Mn0.2 Co0.2 O2 (NMC532) material displays capacity loss and poor rate performance even though it is a widely used cathode in commercial Li-ion batteries (LIBs). In this work, the structural and electrochemical performance of the NMC532 cathode were optimized using the fuel-to-oxidizer ratio assisted sol-gel combustion synthesis (SCS). It was shown that the fuel-to-oxidizer ratio markedly influenced the exothermicity of the combustion reaction which affected the crystal structure, morphology, and electrochemical performance of the final NCM532 materials. The fuel lean (FL) composition produced NMC532 cathode materials with the biggest crystallite and particle sizes, less cation mixing degree and better layered structure compared with the fuel stoichiometric (FS) and fuel rich (FR) compositions. The FL cell presented an initial discharge capacity of 180 mAh g−1 and the highest capacity retention of 92.2 % when it was cycled at 0.1 C between 2.5 and 4.4 V. Also, the FL cell displayed exceptional rate capability with the average capacities reaching 180, 178, 175, and 173 mAh/g at current densities of 1 C, 3 C, 5 C, and 10 C, respectively between 3.0 and 4.6 V. The EIS tests and dQ/dV plots showed that the FL cell both had the least impedance and polarization. The superior electrochemical performance of the FL material was ascribed to its optimized structural properties. Furthermore, the electrochemical results also show the influence of voltage window and current density on the performance of the NMC532 cathode materials.Item High-voltage LiNi0.5Mn1.5O4 cathodes for Li-ion batteries obtained by sol–gel combustion method: effects of fuel-type and silver doping(Sustainable Energy & Fuels, 2025-09-28) Ehi-Eromosele, Cyril O.; Ajayi, Samuel O.; Ikebudu, Jude N.; Abiaziem, Chioma V.; Mathe, Mkhulu K.High-voltage LiNi0.5 Mn1.5 O4 (LNMO) cathode materials are highly desirable for the fabrication of next-generation lithium-ion batteries (LIBs). In this study, citric acid, glycine, and sucrose fuels were used to optimize the structural and electrochemical properties of LNMO materials obtained by sol–gel combustion synthesis (SCS). The experimental results showed that the type of fuel used in the SCS process influenced the enthalpy of combustion, crystallite size, morphology, cationic disorder and electrochemical properties of the LNMO materials. XRD results indicated that all the LNMO materials have a phase-pure spinel structure with the Fd3m space group. The glycine fuel composition produced LNMO material (LNMO-G) with the least crystallite size, less cationic disorder and the highest crystallinity compared with those having the citric acid fuel (LNMO-C) and sucrose fuel (LNMO-S) compositions. As a result, the LNMO-G cell delivered the highest first discharge capacity of 115.83 mA h g−1 and retained 80.06% of its initial capacity after 200 cycles at a current density of 1C. Moreover, the LNMO-G cell had the best rate capability compared with the LNMO-C and LNMO-S cells, with a discharge capacity of 60 mA h g−1 at a rate of 2C between 3.50 and 5.30 V. Furthermore, Ag doping (LNMAO) improved the rate capability and Li-ion kinetics of the LNMO-G cathode material. The LNMAO cathode achieved a reversible discharge capacity of 100 mA h g−1 at a rate of 2C between 3.50 and 5.30 V. These findings show that LNMO cathode materials can be optimized for ultra-high-voltage (>5.0 V) performance in LIBs for advanced applications.Item Exploring layered lithium-rich spinel composite cathodes for lithium-ion battery obtained by the solution combustion-mechanochemical synthesis(Journal of Alloys and Compounds Volume 1038, 2025-08-20) Ehi-Eromosele, Cyril O.; Ajayi, Samuel O.; Shaaban, Ibrahim A.; Assiri, Mohammed A.; Hessien, Mahmoud M.; Abiaziem, Chioma V.; Sunday, Sam E.; Mathe, Mkhulu K.In this study, layered lithium-rich oxides (LLO) cathode materials were modified with different amounts of the spinel phase to form integrated layered-layered-spinel (LLS) hetero-composites [0.5Li2 MnO3 ꞏ (0.5 − x)LiNi0.5 Mn0.3 Co0.2 O2 ꞏ xLiMn1.5 Ni0.5 O4 (0.05 ≤ x ≤ 0.25)] using a facile solution combustion mechanochemical synthesis method for the first time. The XRD results indicate that all the LLS materials have distinct layered and spinel phases with R3m, C2/m and Fd3m space groups. Notably, the initial coulombic efficiency of the LLS materials increased with increase in the spinel content but showed a reduction both in their charge and discharge capacities. The LLS doped with 5 % spinel content (651LLS), exhibited the best electrochemical performance compared to the ones doped with 15 % spinel content, gave the smallest particle size and the largest unit cell volume. Consequently, the 651LLS cell delivered the highest initial discharge capacity of 279.58 mAh g⁻¹ and a capacity retention of 84.71 % after 50 cycles at a current density of 10 mA g⁻¹ within a voltage window of 2.0 – 4.8 V. Additionally, the 651LLS cell demonstrated superior rate capability with the average capacities 275, 225, 200, 155, and 90 mAh g⁻¹ at 10, 20, 50, 100, and 200 mA g−1. This enhanced performance is attributed to the optimised spinel amount and the smaller particle size which facilitated faster Li-ion transport during cycling. Also, the optimal electrochemical behaviour of the 651LLS cathode is linked to its optimum spinel content (∼5 %) which contributed to its improved structural stability. The results show that the amount of spinel in these LLS materials must be carefully tuned in relation to the operating cycling parameters to produce optimum electrochemical performance.Item Recent developments strategies in high entropy modified lithium-rich layered oxides cathode for lithium-ion batteries(ECS Meeting Abstracts, Volume MA2025-01,, 2025) Ajayi, Samuel O.; Ehi-Eromosele, Cyril; Liu, Xinying; Mathe, Mahlanyane KennethLiNi0.5Mn0.2Co0.2O2 (NMC532) is a widely used cathode material in commercial lithium-ion batteries; however, it suffers from capacity degradation and poor rate performance. In this study, sol-gel combustion synthesis (SCS) with a controlled fuel-to-oxidizer ratio (fuel stoichiometric (FS) and fuel-rich (FR) compositions, the fuel-lean (FL)) respectively, was employed to improve the structural and electrochemical performance of the NMC532 cathode. The fuel-to-oxidizer ratio was found to significantly impact the exothermicity of the combustion reaction, which subsequently influenced the morphology, crystal structure, and electrochemical performance of the synthesized NMC532 material. The FL composition produced a well-defined layered structure, the largest crystallite size, and the lowest degree of cation mixing compared to the FS and FR compositions. The FL cell exhibited an initial discharge capacity of 180 mAh/g and the highest capacity retention of 92.2% when cycled at 0.1 C within a voltage range of 2.5–4.4 V. Additionally, it demonstrated superior rate capability, delivering capacities of 180, 178, 175, and 173 mAh/g at current densities of 1 C, 3 C, 5 C, and 10 C, respectively, within a voltage range of 3.0–4.6 V. The electrochemical impedance spectroscopy (EIS) measurements confirmed that the FL cell had the lowest polarization and impedance. The superior electrochemical performance of the FL cathode was ascribed to its improved structural properties.Item Recent developments strategies in high entropy modified lithium-rich layered oxides cathode for lithium-ion batteries(Inorganic Chemistry Communications, 2025-02) Ajayi, Samuel O.; Dolla, Tarekegn H.; Bello, Ismaila T; Liu, Xinying; Makgwane, Peter R.; Mathe, Mkhulu K.; Ehi-Eromosele, Cyril O.Lithium-rich layered oxides (LRLOs) are of intense interest and are regarded as one of the best cathodes for next-generation Lithium-Ion batteries (LIBs). LRLOs are favored due to the low cost of production, high energy densities, voltage, and specific capacity. LRLOs suffer from irreversible capacity loss, poor rate capability, voltage, and capacity fade, which in turn limit their full practical applications and commercialization. Therefore, strategies such as surface coating, surface treatment, composition optimization, and elemental doping have been explored to enhance the structural and electrochemical performance of LRLO. Nevertheless, high entropy (multiple elements) doping has proven to be a very effective strategy due to its simplicity and expansion of LRLO lattice interplanar spacing without damaging their original structure. It is worth noting that there has been little research work on high entropy strategies for modifying LRLO cathode. Thus, the aim of this review is current update on high entropy strategies for modifying LRLO cathode materials.Item Environmental assessment of radionuclide exposure in packaged borehole water exploited from crystalline rocks in Ogbomoso(ICSAEES-2024, Lagos, Nigeria, 2024) Oladipo, A. E.; Aremu, A. A.; Adeniji, A. A.; Ayinla, T. O.; Babarimisa, I. O.; Morakinyo, R. O.; Araka, I. O.; James, U. E.The amounts of naturally occurring radionuclides (40K, 238U and 232Th) in packaged borehole water manufacture have been investigated in this work. Furthermore, the buildup of radioactive materials in drinking water presents a direct path for human population exposure to internal radiation. The amount of radioactivity in the processed and unprocessed water samples was measured using gamma spectrometry and a computer-resident quantum multichannel analyser (MCA 2100R) connected to a well-calibrated and shielded NaI (Tl) detector. From the results, it was revealed that the values of activity concentration of processed water ranges between 50.46 ± 3.14 Bq/L to 102.18 ± 14.07 Bq/L, 7.92 ± 4.46 to 16.71 Bq/L, and 10.00 ± 0.84 Bq/L to 14.87 ± 4.03 Bq/L for 40K, 238U and 232Th, respectively. Also, the results obtained for the activity concentration of unprocessed water ranges between 74.51 ± 3.51 Bq/L to 102.21 ± 7.23 Bq/L, 14.86 ± 1.91 Bq/L to 19.87 ± 3.10 Bq/L and 10.00 ± 3.36 Bq/L to 17.79 ± 4.43 Bq/L for 40K, 238U and 232Th, respectively. The results confirmed the presence of40K as a principal occurring radionuclide in the water samples. The annual effective dose for processed water ranges from 0.012 to 0.017 mSyr-1, while it ranges between 0.015 and 0.020 mSyr-1 for unprocessed water. Results in the present study fall below 0.1 mSyr-1, which is the acceptable limit recommended by International Commission on Radiological Protection standard value.Item Effects of Aerosol Scattering Attenuation on Free-Space Optical Link Performance in Owerri, Southeast, Nigeria(Science and Technology: Developments and Applications Vol. 8,, 2025) Akinwumi, A.; Ayo-Akanbi, O.; Omotosho, T. V; Arijaje, T; Ometan, T.; Adewusi, O.High-speed, point-to-point data transmission through laser beams across terrestrial networks is sometimes referred to as "Free-Space Optics" (FSO). Multimedia applications including social networks, OTT platforms, video conferencing, and multimedia streaming are driving up the demand for data rates and channel bandwidth, which has led to a telecommunications bottleneck. In spite of the several benefits of using free-space optical (FSO) communication systems as complementary platforms for next-generation networks, the existence of atmospheric disturbances such as fog and scintillations are key sources of signal impairment that affect system performance. Thus, it is crucial to learn about the specific weather patterns of the areas where FSO lines will be installed. The purpose of this work is to estimate the availability performance of FSO lines broadcasting at both 850 nm and 1550 nm by performing a statistical analysis of meteorological visibility data gathered for Owerri in Nigeria over a 21-year period (2000-2021). The results show that the visibility during the most common fog events in Owerri is 100 meters. The probabilities of encountering and exceeding the scattering attenuations associated with Owerri's most common fog event are 0.0002 and 0.0229, respectively. This research could be expanded in the future by exploring the effects of varying localized climatic conditions on the many forms of optical signals, such as plane, spherical, and Gaussian beam waves. This would aid in the modelling of different forms of attenuation for deployment sites of FSO or hybrid FSO systems.Item Analysis of Attenuation Due to Atmospheric Gases Prediction Models at Ota, Nigeria(Science and Technology: Developments and Applications Vol. 7, 2025) Akinwumi, A.; Omotosho, T.; Usikalu, M.; Adewusi, M.; Ometan, O.; Emetere, M.The theory explaining the interaction between molecules and radiation of gases in telecommunication ascertained the fact that microwave signals experience significant attenuation that can appreciably degrade the quality of signal transmissions. Millimeter and sub-millimeter wave signals experience scattering and absorption while propagating through the atmosphere. The demand for satellite services is rapidly increasing on a daily basis. One of the major concerns for satellite telecommunication designers is the impacts of gas attenuation on earthspace path links, most importantly in tropical areas. This research has been directed at the analysis and comparison of gas attenuation prediction models at Covenant University, Ota, southwest Nigeria (Lat: 6.7 o N, Long: 3.23o E). Gas attenuation data were collected from the spectrum analyzer and Davis automatic weather station for a period of five years (April 2012- December 2016) from Astra 2E/2F/2G Satellite link set at an elevation angle of 59.9o on 12.245 GHz. The monthly gas attenuation was analyzed and compared with existing gas attenuation prediction models that could provide a guide to microwave propagation engineers in the tropical region. The results suggest that even during clear-sky, gas attenuation still poses a threat to the design of satellite communication on the earth-space path. The results also suggest that even during clear-sky, gas attenuation still poses a threat to the design of satellite communication on the earth-space path. Likewise, the same pattern was observed from 2013 to 2016 where Salonen’s model was reported as the lowest model and Liebe’s model gave the highest value. Therefore, the ITU-R model may be more accurate for modelling gas attenuation for the region. Hence, the statistics provided in this work will help engineers in planning and designing good telecommunication systems in the tropical region.Item Environmental Impact of Pre-occupational radon level measurements in medical imaging facilities of a tertiary hospital in south-west Nigeria(ICSAEES-2024, Lagos, Nigeria, 2024) Aremu, A. A.; Oni, O. M.; Oladipo, A. E.; Oladapo, O. O.; Obafemi, Y. D.; Oniha, M. I.; Babarimisa, I. O.; James, U. E.Radiation facilities are placed in an enclosed environment to prevent scattered radiation from getting out of the room, by so doing the rooms foil gas exchange from the outdoor environment, thereby increasing the radon concentration in the indoor air. This study aimed at estimating the occupational radon exposure level in medical facility room in order to estimate the radiological risk in such environment. RAD7 electronic device was used to measure theindoor radon concentration in the five proposed roomsin the newly built Radiology department of a University Teaching Hospital while a digital thermometer was used to measure the ambient temperature. The radon concentrations ranged between 12.09Bq/m3and 58.52 Bq/m3. The ultrasound room has the least average value of 12.09 Bqm-3 and the Fluoroscopy room has the maximum average value of 58.52 Bqm-3. The radon level translated into the effective dose, working level and excess life-time cancer risk for any worker staying for a period of nine hours per day, over a year. Fluoroscopy facility was estimated to present the highest annual absorbed dose and annual effective dose with 0.73 mSvy-1 and 0.8858 mSv y-1, respectively.The mean radon concentration for the five rooms was 41.96Bq/m3. The calculated annual effective dose rate and the mean annual absorbed dose rate to the lung within the radiation facilities rooms were 0.529 mSvy- 1and 0.6350 mSv y-1, respectively.The indoor radon concentrations measured and the effective dose value of 200 Bq/m3 and 1 mSvy-1 respectively is below the reference limitset by International Commission Radiation Protection (ICRP) Agency.This implies that the radiation facility rooms are in conformity with international best practices and this is in agreement with SDG 3 (Good Health and well –being)