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- ItemIonospheric F2-Region Characteristics of Profile Parameters at an Equatorial Station During Low Solar Activity(Nigerian Institute of Physics, 2023-12) Johnson, Mayowa James; Olusegun, Emmanuel Ehinlafa; Àlàgbé, George AtiladeThe ionospheric characteristics of the F2 region critical frequency (foF2), peak electron density (NmF2) and the height of occurrence of electron density (hmF2), was investigated over Ilorin (lat. 8.31°N, long. 4.34°E, dip lat. 2.95o), a station along the equatorial ionization anomaly trough, during a period of low solar activity (LSA). Diurnally, foF2, NmF2 and hmF2 were found to have two characteristic peaks: pre-noon and post-noon peaks, except hmF2 that has post-sunset peak. The foF2 and NmF2 pre-noon peaks occurred around 0800–0900 LT, hmF2’s peak around 1000 LT. The post-noon peaks of foF2 and NmF2 were observed around 1500 and 1800 LT, while hmF2 was observed around 1800 and 1900 LT. In general, the magnitude of the pre-noon peak is less than that of the post-noon/post-sunset peak for all the parameters, for all the seasons. The highest magnitudes of foF2 and NmF2 were reached in the equinoctial months. The rapid faster electron drift in hmF2 away from the equator is responsible for the sharp drop in foF2 and NmF2 after sunset in all seasons. Seasonal peaks in general are suspected to be controlled by the enhanced E × B drifts and, the atmospheric wind, which is consistent with some earlier results obtained at some stations in the African region during low solar activity periods.
- ItemGraphene@Ni0.5Co0.5Fe2O4 hybrid framework with enhanced interfacial polarization for electromagnetic wave absorption(Elsevier, 2020) Fatai Adisa Wahaab; Wasiu Yahya; Lawal Lanre Adebayo; Issa Kazeem; Abdulganiyu Abdulraheem; Bilal Alqasem; Jemilat Yetunde Yusuf; Abibat Asabi Adekoya; Chai Mui NyukFabrication of smart materials for electromagnetic (EM) wave absorption has been propounded as efficient EM interference and pollution mitigation method. Herein, a porous lightweight graphene@Ni0.5Co0.5Fe2O4 composite was prepared via a co-precipitation method. The results show that Ni0.5Co0.5Fe2O4 nanoparticles are homogeneously dispersed and anchored on the graphene flakes. Investigation of the EM waves absorption properties of the material at different filling in paraffin reveals that at 15 wt% loading, the composite absorbs large percent of the EM waves at minimal thickness. The composite attains optimum reflection loss peak -44.7 dB at 17.45 GHz, with 1.5 mm thickness. This enhanced EM wave absorption performance (at lesser thickness than Ni0.5Co0.5Fe2O4 in literature) could be ascribed to interfacial polarization and a good impedance match arising from unique pore configuration of the dielectric (graphene) and magnetic (Ni0.5Co0.5Fe2O4) composite. These results indicate that the lightweight G@Ni0.5Co0.5Fe2O4 composites with strong absorption at reduced thickness is an efficient absorber for high-frequency EM wave attenuation. absorber for high-frequency EM wave attenuation.
- ItemEffect of Deformation on Alpha Decay of Super-Heavy Nuclei within a Woods-Saxon model(Nigerian Society of Physical Sciences, 2025-03-23) Surajudeen Shittu; Mustapha Abolaji HammadIn this research, alpha decay study of super-heavy nuclei has been carried out by employing the Woods-Saxon model potential. The spherical and deformed Woods-Saxon model have been employed to investigate the effect of deformation on the super-heavy nuclei via alpha decay. When compared with experimental data, the two models are found to perform very well in describing the experimental half-life data. Moreover, results obtained by considering deformation is found to give better agreement with the experimental data than the results using spherical configuration. This is mainly because the super-heavy nuclei have non-zero deformation parameters. The study concludes that deformation should be considered when studying super-heavy nuclei, and that the deformed Woods-Saxon model is more complete in describing the interaction between the alpha decay and the daughter nuclei as it has a low standard deviation value of 0.5012 compared to 0.6260 when only sphericity is considered.
- ItemSolar thermal radiation and Cattaneo-Christov heat transport in magnetohydrodynamic photovoltaic-thermal cooling systems under rotating flow(World Scienti¯c Publishing Company, 2025-11-11) Leila Manai; M. J. Johnson; Saleh Chebaane; A. M. ObalaluThe integration of photovoltaic-thermal (PVT) systems with advanced cooling techniques is crucial for improving energy e±ciency and overcoming performance limitations in solar energy conversion. This study investigates the combined e®ects of solar thermal radiation, Cattaneo{ Christov non-Fourier heat transport and magnetohydrodynamic (MHD) rotating °ow on PVT cooling performance. The purpose is to provide a deeper understanding of how thermal and electromagnetic interactions in°uence heat transfer and system e±ciency, particularly under conditions where conventional Fourier-based models fall short. A carboxymethylcellulose (CMC){water-based base °uid enhanced with nanoparticles zirconium oxide (ZrO2), copper (Cu) and aluminum oxide (Al2O3) is employed as the working medium to further boost thermal conductivity and system e±ciency. A mathematical model is developed to capture the dynamics of radiative heat °ux, magnetic ¯eld, rotation and nonlinear thermal relaxation e®ects. The governing equations are transformed into dimensionless form and solved numerically using a Chebyshev collocation method. The results demonstrate that the inclusion of ZrO2, Cu and Al2O3 nanoparticles in the CMC{water base °uid signi¯cantly improves thermal conductivity, thereby enhancing the system's cooling capacity. Under solar thermal radiation, ternary hybrid nano°uids demonstrate approximately 20% superior thermal regulation. The novelty of this work lies in the synergistic analysis of MHD rotating °ow, Cattaneo{Christov heat transport and nanoparticleengineered CMC-based °uids for PVT cooling, providing new physical insights and practical guidelines for the design of high-performance renewable energy systems.
- ItemMorphology of Ionospheric foF2 And NmF2 over Ilorin during Low Solar Epochs(Mountain Top University Journal of Applied Science and Technology (MUJAST, 2023) Johnson, Mayowa JamesThe F2 region critical frequency (foF2) and peak electron density (NmF2) morphology was investigated over Ilorin (latitude 8.31°N, longitude 4.34°E) during a Low Solar Epochs (LSE), a station along the equator anomaly trough. Diurnally, foF2 and NmF2 are visibly more prominent during the day than at night with two characteristic peaks: pre-noon and post-noon peaks. The foF2 and NmF2 pre-noon peak magnitude range: (7.7–8.3 MHz) and (7.3–8.6) × 1011 /m-3 respectively is less compared to the foF2 and NmF2 post-noon peak magnitude range: (7.3–9.7 MHz) and (6.7–11.7) × 1011 /m-3 respectively. Seasonally, the highest values were attained during the post-noon peak in the equinoctial months compared to the solstices months, and also, annually, the post-noon peak is higher than the pre-noon peak. The rapid electron drift away from the equator is responsible for the sharp drop in foF2 and NmF2 after sunset in all seasons. Seasonal peaks in foF2 and NmF2 are suspected to be controlled by the enhanced E × B drifts and the onset and turn-off of solar ionization, which is consistent with some earlier results obtained at some stations in the African region during low solar epoch periods.