Reliable knowledge of local meteorological variability is a prerequisite for technically sound siting and grid integration of a utility-scale solar photovoltaic (PV) farm. This study statistically analysed eleven years (2015–2025; N = 132 monthly observations) of rainfall amount, rainfall rate, relative humidity and sunshine duration for Rivers State, Nigeria, and translated the results into practical guidance for solar PV development in support of Sustainable Development Goal 7 (Affordable and Clean Energy), Goal 13 (Climate Action) and related goals. Descriptive statistics, one-way analysis of variance (ANOVA), Pearson correlation, ordinary least-squares regression and the non-parametric Mann–Kendall/Sen's-slope trend tests were applied, and regression-based proxy-forecast models for sunshine duration and global horizontal irradiance (GHI) were developed and validated on a 2024–2025 hold-out sample. All four variables showed pronounced and statistically significant seasonal variation (ANOVA p < 0.001) but no statistically significant inter-annual trend over the study period (Mann–Kendall p > 0.05 in all cases), indicating a strongly seasonal but climatologically stable resource base. Sunshine duration averaged 7.68 ± 1.54 h/day (CV = 20.0%) and was strongly and significantly negatively correlated with relative humidity (r = − 0.827) and rainfall amount (r = − 0.723, p < 0.001 in both cases). The best-performing proxy model (sunshine and rainfall jointly predicting GHI) achieved a hold-out R² of 0.802 and MAPE of 3.90%, supporting its use for month-ahead solar-resource forecasting. Using the Angstrom–Prescott relation calibrated for Port Harcourt, estimated GHI averaged 6.03 kWh/m²/day (mean clearness index 0.61), with an indicative mean PV capacity factor of 19.6%, rising above 23% in the December–February dry season and falling to about 17% during the June – October rains. A composite site-suitability index built from the standardised sunshine, rainfall and humidity series identified December–February as the optimal window for civil works, panel installation and peak energy yield, and June–October as the period of highest cloud cover, soiling risk and grid-integration variability. These findings support siting solar PV assets on well-drained upland sites away from flood-prone terrain, sizing inverters and battery/storage buffers to accommodate pronounced wet-season output dips, and scheduling major construction and maintenance during the dry season, which collectively strengthen the technical and economic case for grid-connected solar deployment in Rivers State.
This study evaluated selected correlation models for estimating daytime profiles of global solar radiation on a horizontal surface and ambient temperature at a measurement site in Ouagadougou, Burkina Faso. Experimental data were collected using a pyranometer, a K-type thermocouple and a data logger installed at Joseph KI-ZERBO University. Measurements were recorded at five-minute intervals during selected days in December, January, March and April, and monthly average daytime profiles were obtained. Two trigonometric correlations previously used in existing literature were first applied to describe the temporal variation of solar radiation and ambient temperature. In addition, Gaussian-type correlations were developed using non-linear regression in MATLAB to represent the measured profiles. For global solar radiation, the literature-based sine model produced coefficients of determination between 0.96 and 0.98, with RMSE values ranging from 36.3 to 51.3 W/m². The proposed Gaussian model produced R² values between 0.96 and 0.98, with RMSE values ranging from 33.0 to 51.0 W/m². For ambient temperature, the literature-based model gave R² values between 0.94 and 0.97 and RMSE values between 0.55 and 0.76 °C, while the Gaussian model gave R² values between 0.96 and 0.98 and RMSE values between 0.37 and 0.63 °C. The results indicate that both approaches describe the measured daytime profiles with acceptable agreement.
Petroleum exploration and production can introduce potentially toxic metals into the soils and water bodies of host communities, with consequences for both ecosystem integrity and human exposure. This study assessed the concentrations and distribution of ten heavy metals: Ni, Cr, Cu, Co, Pb, Cd, Fe, Mn, As and Zn in soil and water from two oil-field communities, Apkai (Ndokwa East Local Government Area) and Umusedege (Ndokwa West Local Government Area), Delta State, Nigeria. A total of 63 soil samples and 11 water samples were collected across the two communities and a nearby control site (Obetim). Soil metals were determined by atomic absorption spectrophotometry (AAS) and, for Zn, Fe and Cu, cross-checked by X-ray fluorescence (XRF); water metals were determined by AAS alone. Overall mean soil concentrations were 148.58, 254.41, 53.15, 0.16, 229.98, 21.85, 2905.61, 1228.55, 0.58 and 175.87 mg kg⁻¹ for Ni, Cr, Cu, Co, Pb, Cd, Fe, Mn, As and Zn, respectively, with Fe as the dominant element throughout. Relative to the control, Cr, Cu, Co, Pb, Cd, Fe, Mn, As and Zn were all elevated in soil, while Ni was slightly lower; the largest soil enrichment ratios were recorded for Mn (2.10×), As (1.81×) and Cr (1.76×). In water, mean concentrations were 0.14, 0.04, 0.13, 0.35, 0.03, 6.91, 1.25 and 0.30 mg L⁻¹ for Ni, Cr, Cu, Pb, Cd, Fe, Mn and Zn, respectively (Co and As were not detected), with Pb (10.77×) and Zn (10.17×) showing by far the largest enrichment relative to the control. The AAS–XRF comparison showed statistically significant differences for Zn, Fe and Cu (p < 0.05 in all cases); XRF consistently returned higher values than AAS. Measured against the soil guideline values reproduced in the underlying study, Ni, Cr, Cu, Pb, Cd, Fe and Mn all exceeded their respective thresholds, most markedly Mn, Fe, Cd, Cr and Pb; in water, Fe, Pb, Cd, Ni and Mn were flagged as being of particular concern against U.S. EPA, WHO and SON reference values. Taken together, the results indicate substantial, spatially uneven alteration of soil and water metal concentrations in this oil-field environment relative to the surrounding background, consistent with a combination of lithogenic and anthropogenic contributions, and establish a concentration baseline for the pollution-index, fractionation and health-risk assessments that build on this dataset.
A post-commissioning radiological assessment was conducted to evaluate the radiological status of soil and water in three host communities, Idaso, Ilege, and Mobido, located around the Dangote Petroleum Refinery in Ibeju-Lekki, Lagos, Nigeria. Seven composite soil samples and three composite water samples were collected and analysed by gamma-ray spectrometry using a 3″ × 3″ NaI(Tl) detector. The activity concentrations of naturally occurring Potassium – 40 (40K), Uranium -238 (238U) and Thorium -232 (232Th) were determined, and selected radiological parameters, including absorbed dose rate, annual effective dose, radium equivalent activity, external hazard index and annual ingestion dose, were evaluated. Mean soil activity concentrations (Bq/kg) were 191.29 ± 11.74, 16.17 ± 5.13 and 14.53 ± 3.78 for 40K, 238U and 232Th, respectively, all below the corresponding UNSCEAR reference values. In water, mean activity concentrations (Bq/L) were 71.73 ± 14.76, 4.45 ± 3.53 and 2.04 ± 0.97 for 40K, 238U and 232Th, respectively. The mean absorbed dose rate for soil and the corresponding mean annual effective dose were 24.22 nGyh-1 and 0.030 mSvy-1, respectively. The mean radium equivalent activity in soil was 51.68 Bq/kg and the mean external hazard index was 0.140, indicating a low external gamma-radiation hazard. However, the total annual ingestion dose due to water intake from 238U and 232Th ranged from 0.277 to 0.770 mSvy-1, with a mean of 0.489 mSvy-1, exceeding the 0.1 mSvy-1 reference criterion. The findings indicate that the post-commissioning radiological status of the study area is generally within the evaluated reference levels for external exposure, but the elevated ingestion dose estimates warrant continued monitoring and further assessment of radionuclide contributions in water.
Decades of tin extraction on the Jos Plateau have left behind heavily reworked ground, including open pits, spoil heaps and slurry deposits, much of which has gradually been absorbed back into local farming. This paper re-examines a field investigation of that reclamation process, focusing on how much lead (Pb), cadmium (Cd) and zinc (Zn) have built up in the farm soils and Irish potato (Solanum tuberosum) tubers grown around three disused mining excavations at Dahwol-Vwana village, Kuru District, Jos-South Local Government Area, Plateau State. Paired soil and tuber samples were drawn from fifteen points encircling the excavations, with soil taken 10–20 cm beneath the surface of established potato ridges; a comparatively undisturbed site supplied the control material. After wet-acid digestion, metal content was determined by atomic absorption spectrometry (AAS). Soil concentrations spanned 0.0445–3.9343 mg kg⁻¹ for Pb, 0.0086–0.1200 mg kg⁻¹ for Cd and 0.0751–39.0302 mg kg⁻¹ for Zn, while tuber concentrations spanned 0.0741–1.5042, 0.0081–0.0931 and 0.1038–88.0503 mg kg⁻¹, respectively. Every soil sample remained below the international guideline values used for comparison, yet all three metals were consistently higher than in the control soil. Measured against the food-safety benchmarks adopted in the source study, tuber Cd remained within limits throughout, whereas Pb exceeded 0.1 mg kg⁻¹ in eleven of twelve tuber samples and Zn exceeded 15 mg kg⁻¹ in four samples. Taken together, the findings suggest that although the bulk soils were not heavily contaminated by the standards applied, localised enrichment of Pb and Zn in the edible tuber tissue is sufficient to justify continued monitoring of food crops raised on reclaimed mine land.
Magnetohydrodynamic (MHD) nanofluids have emerged as promising working fluids for advanced thermal management systems owing to their enhanced heat transfer capability and controllable transport characteristics under external magnetic fields. This study presents an analytical investigation of coupled energy and mass transport in Fe₃O₄–water nanofluid flow through a chemically reacting porous rectangular channel under the influence of thermal radiation. The novelty of the present work lies in the integration of established thermophysical property correlations for effective viscosity, thermal conductivity, and electrical conductivity with an analytical Laplace transform framework to investigate the combined effects of magnetic field, buoyancy, thermal radiation, nanoparticle volume fraction, and chemical reaction on transport phenomena in porous media. The governing momentum, energy, and concentration equations are formulated using the Buckingham π theorem to obtain the corresponding dimensionless model and are solved analytically using the Laplace transform technique, subject to the prescribed boundary conditions. The developed analytical solutions are employed to examine the influence of the governing dimensionless parameters on the velocity, temperature, and concentration distributions. The analytical results demonstrate that variations in nanoparticle volume fraction significantly modify the thermal and concentration fields through changes in the effective thermophysical properties of the Fe₃O₄–water nanofluid, while an increase in effective viscosity alters fluid momentum transport. The Hartmann number acts as a resistive parameter that suppresses the velocity profile through the Lorentz force, whereas the effects of thermal radiation and chemical reaction on the transport fields are shown to be consistent with the governing equations and the validated analytical solutions. Representative analytical results indicate that changes in the governing parameters produce measurable variations in the velocity, temperature, and concentration distributions under the investigated operating conditions. The proposed analytical model provides improved physical insight into coupled magnetohydrodynamic heat and mass transfer in chemically reacting porous media and offers a reliable theoretical framework for validating numerical models and supporting the design and optimisation of electronic cooling systems, porous thermal devices, energy conversion systems, and other engineering applications employing Fe₃O₄–water nanofluids.
This study presents a cycle-to-date classification and geoeffectiveness analysis of the interplanetary drivers of geomagnetic storms during Solar Cycle 25 (SC25), from December 2019 to 24 June 2026. Hourly OMNI solar-wind plasma and interplanetary magnetic-field data were analysed together with the Dst, Kp, and AE indices. A total of 111 storms with minimum Dst <= -50 nT were identified and assigned to interplanetary coronal mass-ejection (ICME) ejecta or magnetic clouds, sheath regions, combined sheath-plus-ejecta (S+E) structures, or corotating interaction region/high-speed-stream (CIR/HSS) drivers. The catalogue contains 86 moderate, 19 intense, five superintense, and one extreme storm. S+E structures account for 65 storms and 23 of the 25 storms at intense or stronger levels (92%), including all six superintense-or-extreme events. CIR/HSS storms (n = 28) are almost exclusively moderate. Across the full sample, minimum Dst is most strongly associated with peak southward IMF Bz (r = 0.85) and maximum dynamic pressure (|r| = 0.80); the Bz-Dst relationship is tighter for S+E events (r = 0.87) than for CIR/HSS events (r = 0.52). The relative CIR/HSS contribution increases during the declining phase, while ICME-related activity remains substantial. A constant-coefficient linear Burton-type model provides limited pooled hindcast skill, particularly for CIR/HSS storms. A nonlinear threshold-injection formulation with driver-dependent decay scaling, calibrated on pre-2025 storms and evaluated on 2025-2026 storms, yields correlations of r = 0.86-0.91 and prediction efficiencies of 0.74-0.81 across the principal driver classes. Storm-level cross-validation and sensitivity testing indicate that these cycle-to-date conclusions are not driven by a single fitting split or by the uncertain classification of moderate storms. Because the analysis concerns one incomplete solar cycle and relatively few extreme events, the inferred S+E dominance should be treated as an SC25-specific finding requiring confirmation across additional cycles.
Manual operation of barriers at access points can increase operator workload and may delay vehicular movement. This study designed, constructed, and evaluated a remote-controlled gate cross bar intended to provide a low-cost wireless alternative for automated access control. The system integrated an Arduino Uno microcontroller based on the ATmega328P, a 433 MHz radio-frequency transmitter and receiver, a 12 V DC geared motor, a motor-driver module, limit switches, relay control, status indicators, and a mechanical barrier arm. The control program processed remote commands, activated bidirectional motor movement, and used limit-switch feedback to stop the barrier at the fully open and closed positions. Performance was evaluated under outdoor conditions using 20 opening-and-closing cycles. The measured parameters included response time, opening time, closing time, remote operating range, and operational consistency. The system recorded a mean response time of 0.61 ± 0.05 s, a mean opening time of 2.43 ± 0.08 s, and a mean closing time of 2.48 ± 0.07 s. Stable RF communication was maintained over an average distance of 25 ± 1.2 m. Temporary electromagnetic interference, metallic obstacles, reinforced-concrete walls, and minor power-supply fluctuations affected signal reception or motor speed during some observations. No mechanical failure, motor overheating, excessive vibration, or structural deformation was reported during testing. The developed prototype demonstrated the practical integration of locally available mechanical and electronic components for wireless gate operation, although further evaluation under broader field conditions is required.
Proton exchange membrane fuel cells (PEMFCs) are electrochemical systems that directly convert the chemical energy of hydrogen into electricity, offering high energy efficiency and low environmental impact. Within these systems, the gas diffusion layer (GDL) plays a critical role in ensuring efficient reactant transport and uniform current distribution. This study examines the influence of GDL tortuosity on PEMFC performance. A numerical model, incorporating the Maxwell-Stefan transport laws for multi-species diffusion, the Butler-Volmer equation for electrochemical kinetics, and Darcy’s law for flow in porous media, was developed using COMSOL Multiphysics. The main originality of this work lies in the explicit analysis of anisotropic tortuosity, contrasted with the isotropic case, in order to evaluate its effects on species transport and current density distribution. The results show that increasing tortuosity significantly limits reactant diffusion, leading to a reduction in cell performance of up to 20-80 % at low current densities. Polarization curve analysis indicates a decrease in cell efficiency as tortuosity increases. In addition, anisotropic tortuosity induces spatial heterogeneities in diffusion pathways, resulting in non-uniform current density distribution and further performance losses. These findings highlight the critical role of GDL microstructure in PEMFC operation and provide practical insights for the design and optimization of GDL materials. Specifically, controlling tortuosity and its anisotropy can improve reactant transport, enhance efficiency, and increase the durability of fuel cells under realistic operating conditions.
This study examines the combined influence of magnetic field and operating temperature on charge-carrier transport parameters in a polycrystalline silicon radial junction solar cell. The analysis focuses on carrier mobility, diffusion coefficient, and diffusion length, which are central to the collection of photogenerated carriers and the photovoltaic performance of the device. The results indicate that increasing temperature reduces carrier mobility because of stronger carrier–phonon interactions. This reduction in mobility also decreases the diffusion coefficient and diffusion length, thereby limiting the ability of charge carriers to reach the junction before recombination. The applied magnetic field also affects transport behaviour through the Lorentz force, which deflects carriers from their initial trajectories and reduces their effective mobility and drift velocity. At low magnetic fields, below 10⁻⁴ T, the diffusion coefficient and diffusion length remain nearly constant. In the intermediate range of 10⁻⁴ T to 10⁻² T, both parameters decrease progressively, while for magnetic fields above 10⁻² T, strong carrier confinement produces a marked limitation of transport. The maximum diffusion length is approximately 20 µm near room temperature, around 300 K, in the absence of a magnetic field or under very weak magnetic fields. These findings indicate that a base radius close to 20 µm is suitable for improving carrier collection in the studied radial junction configuration.
Caladium tricolor tuber starch (CTS) was extracted and used as corrosion inhibitor for mild steel in 0.5M HCl and 0.5M H2SO4 acid media respectively at various concentrations using the gravimetric technique. Results obtained shows that inhibition efficiency of the CTS inhibitor varied with time and concentration. Inhibition efficiency of caladium tricolor starch obtained ranged from 60% - 95% at 0.3g – 0.9g concentration in both acidic media. Maximum efficiency was obtained at concentration of 0.9g at 48 hours in 0.5M H2SO4. The highest inhibition efficiency obtained in HCl media was 90.03% at 0.9g/L concentration after 24 hours while 95.40% was obtained in H2SO4 media at 0.9 g/L after 48 hours, indicating CTS performed better in H2SO4 than in HCl. The mode of adsorption of the caladium tricolor starch followed the Langmuir isotherm exhibiting a Gibbs free energy value of −15.246KJ/mol, which indicates strong adsorption of the caladium tricolor starch molecules on the mild steel substrate.
This study presents a spectral collocation analysis of entropy generation in a laminar boundary layer flow with coupled heat and mass transfer. The model considers a steady, two-dimensional, incompressible, and Newtonian flow over a flat plate with constant thermophysical properties and negligible pressure gradient. Through similarity transformations, the governing equations for momentum, energy, and species concentration are reduced to a system of coupled nonlinear ordinary differential equations. The resulting boundary value problem is solved using the Spectral Collocation Method with Chebyshev polynomials, which ensures high numerical accuracy and rapid convergence. Entropy generation arising from thermal gradients, viscous dissipation, and mass diffusion is quantified, and the effects of key dimensionless parameters, including the Prandtl number, Schmidt number, and Brinkman number, are systematically investigated. The results show that entropy generation is highest near the wall due to steep velocity, temperature, and concentration gradients and decreases rapidly across the boundary layer. Increasing Prandtl and Schmidt numbers enhances thermal and concentration gradients, leading to higher irreversibility, while the Brinkman number significantly increases entropy generation through viscous heating. Bejan number analysis indicates that thermal irreversibility dominates near the surface, whereas viscous and diffusion effects become more pronounced away from the wall. Although based on an idealized boundary layer configuration, the findings provide meaningful insight into energy degradation and coupled transport mechanisms, with potential relevance to near-surface environmental and atmospheric processes. The study demonstrates the effectiveness of spectral methods for accurately resolving nonlinear transport phenomena.
Cassava processing is commonly performed with manual tools such as knives, machetes and mortars, making the operation laborious and time-consuming. Mechanised processing units can reduce this workload, but their electrical requirements must be characterised to support efficient operation and energy planning. This study evaluated the no-load electrical behaviour of a mechanised pilot cassava processing unit installed in Ouagadougou. The unit comprised four main items of equipment: a washer, a peeler, a grater and a spin dryer, each driven by a three-phase low-voltage asynchronous motor. Electrical measurements were conducted under no-load conditions for 60 minutes, with measurements taken at 5-minute intervals. The two-wattmeter method was used to determine voltage, current, active power, reactive power, apparent power and power factor. The results showed that the average active power values of the peeler, washer, grater and spin dryer were 328 W, 762 W, 1005 W and 4506 W, respectively. The corresponding average power factor values were 0.98, 0.98, 0.83 and 0.82. The spin dryer had the highest no-load energy demand and consumed approximately 4.5 kWh during one hour of operation, whereas the peeler consumed approximately 0.3 kWh. Reactive power was nearly zero for the washer and peeler, approximately -1000 VAr for the grater and between 2000 VAr and 4000 VAr for the spin dryer. These findings provide a baseline for understanding idle operation and identifying equipment with higher no-load energy demand.
Aims: The microscopic double folding potential is more superior over the conventional square-well potential as it more realistic to represents the nuclear interactions and the introduction of an imaginary potential provides an effective and compact way to model absorption in nuclear well. Study Design: The computations of nucleus-nucleus potential are implemented in the framework of double folding model function with DDM3Y-Reid and DDM3Y-Paris effective N-N interaction. Among different kind of the effective interaction, the so-called DDM3Y interaction was used in the double folding potential calculations. Methodology: At astrophysical energy regime, the study of the nuclear fusion cross-sections is formidable on account of the massive vastness of the Coulomb barrier, yield in a minute worth of the fusion cross-section. All achievement in the results on S-function towards light particles can gives a clear insights about Big Bang nucleosynthesis. Presently, we have theoretically examined the E dependence of S-function and nuclear fusion σ(E) for fusion reaction of light nuclei for 3He(D,P)4He and 3He(T,N+P)4He nuclear system using complex potential with Coulomb repulsive potential. Results: The calculation of the cross section and S-function cooked in the foundation of the SRTM potential function approach. Conclusion: Theoretical computed results matched with the experimental results.
In the West African region, power system integration through the West Africa Power Pool (WAPP) is a strategic initiative aimed at enhancing energy security and facilitating cross-border electricity trade. Despite significant progress in regional interconnections, the efficiency and financial performance of electricity networks remain severely constrained by high levels of technical and commercial losses. Recent assessments indicate that average technical losses reach approximately 9.1%, while non-technical (commercial) losses account for nearly 21%, revealing persistent structural deficiencies in network operation and management. Technical losses are primarily driven by aging infrastructure, overloaded transmission and distribution lines, inadequate maintenance practices, and the limited deployment of advanced monitoring and control systems such as SCADA and smart grid technologies. Commercial losses, on the other hand, result from inaccurate metering and billing systems, illegal connections, electricity theft, and low revenue collection rates, often compounded by weak governance and insufficient regulatory enforcement. Addressing these challenges requires a comprehensive and coordinated approach, including network modernization through digitalization and smart metering, capacity building for utility operators, harmonization of regulatory frameworks across WAPP member states, and increased consumer awareness regarding responsible electricity consumption. Implementing such measures would significantly reduce system losses, improve the financial sustainability of power utilities, enhance supply reliability, and strengthen subregional energy cooperation in West Africa.
The building sector is one of the most energy-intensive and has the most impact on the environment, due to the use of cement for the manufacture of cinder blocks and concrete. Earth-based materials, thanks to their good thermal inertia, combined with a good choice of roof shape, such as domed roofs, are an alternative for reducing energy consumption and improving thermal comfort. To highlight the hygrothermal performance of earthen buildings with domed roofs, numerical modelling and simulation are used. Modeling is a tool that allows to predict physical phenomena in the building and the modeler must ensure the model's ability to predict them accurately before any simulation. The objective of this study is to experimentally validate a numerical model describing the hygrothermal transfers in an earthen building built with a hemispherical dome roof. The numerical model is implemented in the Comsol Multiphysics software. The meteorological data of the site, the air temperature, the relative humidity of the indoor environment and the temperatures of the interior and exterior surfaces of the building walls are measured. The data acquisition system consists of thermocouples, solarimeters and moisture meters, and this data is processed with Excel and Origin Pro software. Comparison of the simulated data and the measured data shows good agreement. The evaluation of the validation indicators shows that the NMBE values are between -5.63% and 0.3%, the CVRMSE between 0.75% and 7.42% and R2 between 76% and 96%. These values meet the limits recommended by ASHRAE Guideline 14 and show that the model can be used to reliably simulate internal and external thermal variations in the building while highlighting the effects of thermal inertia in the building walls. This research thus proposes a validated model that can be used in future parametric studies and for the optimization of the thermal performance of buildings.
The corrosion inhibition performance of native starch (NS), alkaline-modified starch (MS), polyethylene glycol (PEG), and their blends on mild steel in acidic medium was evaluated using weight loss measurements over 120 h. Single inhibitors exhibited moderate inhibition efficiency at 24 h, with PEG showing the highest initial performance, but all single systems experienced a decline in efficiency with increasing exposure time due to desorption. Adsorption behavior at 24 h followed the Langmuir isotherm with R² > 0.99 for all inhibitors, indicating monolayer adsorption. Calculated adsorption equilibrium constants followed the trend NS > MS > PEG, while standard free energy values ranged from −19.6 to −20.8 kJ/mol, suggesting mixed physisorption and chemisorption mechanisms. Synergy analysis revealed that most blends exhibited antagonistic behavior at 24 h due to competitive adsorption. However, the 0.1 g/L MS + 0.4 g/L PEG blend developed strong synergy over time, with a synergy parameter of 1.64 at 120 h and inhibition efficiency increasing from 46.4% to 89.5%. This indicates that MS pre-adsorbs on the steel surface and facilitates the formation of a stable PEG protective film, leading to sustained corrosion inhibition. The results demonstrate that strategic blending of inhibitors with complementary adsorption properties can provide effective long-term corrosion protection in acidic environments.
This study presents a comprehensive annual assessment of the operational performance of the Souapiti Hydropower Dam, based on data finalized on December 25, 2025, at 24:00. Key energy, hydrological, and operational indicators were carefully evaluated to assess the dam’s contribution to national electricity generation and its compliance with the Power Purchase Agreement (PPA). Over the year, the dam generated a total of 2,286,763.70 MWh, exceeding the PPA target by 20.42%, with a daily average output of 229.18 MW. A minor underperformance was observed in December, attributed to operational adjustments and seasonal variations in hydrology, highlighting the importance of adaptive management strategies. The reservoir remained well within safe operating levels, maintaining an active storage of 23.89 m and a water level of 208.89 m, ensuring both energy production and environmental safety. Coordination with the Souapiti–Kaléta (S+K) complex further optimized overall system performance, resulting in an average combined power of 349.92 MW at an operational load of 50.71%. These results confirm that the Souapiti Dam operates with high efficiency and plays a strategic role in Guinea’s national energy security. They underscore the need for continuous monitoring, predictive management, and adaptive operational strategies to maintain sustainable, reliable, and resilient energy production over the long term.
This study examines the statistical relationship between solar flare classes and the occurrence of associated coronal mass ejections (CMEs) during solar cycles 23 and 24, covering the period from 1 January 1996 to 31 December 2019. The analysis considers CME angular width and speed, with CMEs grouped into narrow, normal, partial-halo, and full-halo categories. A total of 396 flare-associated CME events were considered, including 236 events during solar cycle 23 and 160 events during solar cycle 24. Among these events, 1 was associated with an A-class flare, 23 with B-class flares, 110 with C-class flares, 176 with M-class flares, and 86 with X-class flares. The results show that M-class flares were the most frequently associated flare class across the CME categories. Narrow CMEs were mainly associated with M-class flares, while normal CMEs showed a broader distribution involving C-, M-, and X-class flares. Partial-halo CMEs were the dominant angular-width category in the dataset and were mostly associated with M-, C-, and X-class flares. No full-halo CME with an angular width of 360° was recorded in the analysed sample. The speed distribution indicates that CMEs associated with M- and X-class flares were more frequently represented in higher-speed ranges, including events above 1500 km/s and, in some cases, above 2200 km/s. In the narrow-CME subset, the few X-class flare associations occurred only in the higher-speed categories. Overall, the results suggest that CME angular width alone does not determine CME speed or the intensity class of the associated solar flare. The findings should therefore be interpreted as a descriptive statistical assessment of flare-associated CME properties, while direct evaluation of CME geoeffectiveness would require additional in situ solar-wind and geomagnetic-response data.
This article presents a numerical study of the thermal behavior of walls made from different materials in a hot and dry climate, constituting a first step of thesis work. The main objective is to analyze the temperature evolution inside walls built of hollow cement blocks and local materials (CEB, CLB, and adobe), in order to identify the least performing material in terms of thermal insulation, with a view to subsequently improving its properties. The governing equations were solved using the finite element method, implemented in the COMSOL Multiphysics software (version 5.3). The study was structured around two axes: the analysis of the temperature evolution at the internal and external surfaces of the walls, and the study of the influence of the position of a cement and plaster-based coating layer on the thermal behavior of the walls. The results obtained indicate that temperature peaks are significantly higher in hollow cement block walls (38.55°C) than in those built with local materials [35.07-35.23°C]. These observations show that hollow cement block presents low thermal performance in Sahelian zones, due to its high capacity to rapidly accumulate heat. In perspective, future work will aim to propose solutions to improve the thermal performance of this material.
