Andrew Ragai Henry Rigit

Solar–hydro hybrid energy systems combine rapidly varying photovoltaic output with slower hydraulic dynamics, necessitating source-aware online adaptation. This study evaluates a software-in-the-loop monitoring and forecasting framework using a compact Hedge-adaptive backpropagation neural network with separate solar and hydro feedback gains. The dataset comprises 3,843 mixed-source observations collected from 18 July 2026 at 22:35 to 17 August 2026 at 00:13. Irradiance and ambient temperature were obtained from external weather-model outputs, rainfall was retrieved from a public service when available, hydraulic states were simulated, and hybrid power was constructed as a reference rather than obtained from independently metered plant output. Feature engineering generated 3,823 model-ready targets, which were evaluated using a chronological 60/20/20 development–validation–test split, with scaling fitted exclusively on the development set. On 764 common final-test targets, dual feedback reduced the mean absolute percentage error (MAPE) from 6.80 ± 3.04% for the matched no-feedback Hedge-BPNNT to 2.47 ± 0.57% across five prespecified random seeds. However, support vector regression (SVR) achieved the lowest one-step MAPE of 0.96% and the lowest MAPE at all 24 continuity-safe forecast lead times in the four-hour comparison. For the largest 10% of ten-minute power changes, dual feedback outperformed persistence, long short-term memory (LSTM), and the no-feedback variant, but remained inferior to SVR and Random Forest. The mean computation time for dual feedback was 0.111 ms per one-step prediction and update and 3.409 ms per 24-step recursive forecast. These findings indicate that source-specific feedback provides a useful adaptation mechanism within a matched neural-network architecture, while SVR delivers the strongest overall forecasting accuracy on the constructed-reference dataset.

Dust generated during coal mining and transportation poses serious threats to miners’ health, operational safety, and the surrounding environment. However, comprehensive review studies on dust suppression in coal mines remain limited, particularly those integrating dust movement laws with numerical simulation approaches. This review presents a systematic and reproducible analysis of dust control methods in coal mines with a particular focus on numerical simulation. Current research progress and development trends are summarized from three aspects: structural optimization of dust suppression devices, optimization of operating conditions, and ventilation system design. Existing studies indicate that structural improvements mainly concentrate on nozzle geometry, diameter, installation position, and spraying distance, while operating condition optimization primarily involves pressure regulation. Due to the complexity and high cost of full-scale experimental platforms, ventilation system optimization is largely achieved through numerical simulation, supplemented by field measurements. Studies based purely on numerical simulations remain limited in addressing the chemical modification of dust removers; however, with the advancement of molecular dynamics techniques, this area may represent a promising direction for future research.

In this study, we investigated the flow hydrodynamics of mixture of steam and water through a pipe that has grooved walls. The walls were roughened using collars that has circular and squared shapes throughout the inner walls of the flow channel. Our findings indicate that the factors related to the friction of the walls have been associated with wall roughness ranged from 0.6 to 0.63. The velocity deficit near the wall was slightly greater above the smooth walls compared to the rough walls, reflecting the impact of the friction factor. However, the profiles used to quantify the Reynolds normal stresses showed a distinct contrast. In the grooved surface channel, pressure-induced drag dominated, leaving little room for viscous effects and resulting in lower peaks. These stresses were heavily influenced by wall geometry. Notably, in channels with squared grooves, flow profiles were shows a slight decrease compared to those observed over smooth and rough walls.

The transition towards sustainable energy is crucial for mitigating climate change and reducing dependence on limited fossil fuels. This study aims to optimise the utilisation of biogas generated from palm oil mill effluent (POME) in dual fuel engines through computational fluid dynamics (CFD) simulation. However, this study addressed the challenge of variation in the composition of raw biogas. These differences may make it difficult to effectively control the combustion of internal combustion engines. Thus, to overcome this challenge, the composition of biogas is fixed throughout the cleaning and reforming stages in this study. Using a three-dimensional computational model to evaluate the operation of a single-cylinder compression ignition engine at 1300 rpm under traditional diesel and dual fuel conditions. Due to the symmetry of the cylinder and the periodic pattern of the injector nozzle holes, a 60-degree sector grid representing one-sixth of the cylinder was selected to simulate the entire geometric shape. Using ANSYS Forte software for CFD combustion simulation, this study investigates the effects of reforming biogas substitution on the indicated average effective pressure, total power, thermal efficiency, combustion efficiency and emission characteristics of nine different biogas diesel components (from 0% to 0%). 80% biogas substitution is 20% step size. The research results indicate that replacing diesel with gas fuels such as reformed biogas in dual-fuel engines can affect the performance and efficiency of the engine. Although combustion efficiency and thermal efficiency may initially increase, they will significantly decrease at higher substitution rates, especially at 80%. Nevertheless, reforming biogas still has advantages such as reducing emissions and maintaining output power at medium to high loads. However, compared to traditional diesel engines, challenges such as decreased volumetric efficiency and indicated mean effective pressure (IMEP) lead to an overall decline in engine performance.

This study presents an experimental investigation into the impingement of a supersonic steam jet onto a wall. Steam was injected through a supersonic nozzle at a varying total pressure of 1.5-3.0 bars, producing a supersonic steam jet at a pressure gradient of 0.5-2.0 bars. The whole fluid domain is comprised of two regions: the jet region and the region near the wall involving the impingement of the supersonic steam jet. Within this region, the transformation of primary vortices into secondary vortices occurs and these vortices expel outward in the radial direction after impingement. Measurements have shown the spreading of the normalized density of the vortical structures along the axial length within the region near the wall. However, the probability density function analysis has indicated that the vortical structures become denser within the impingement region. Whereas subsequent to an impingement of the steam jet onto the wall, along the radial direction, weak traces of their existence in the jet region may be attributed to the vorticity diffusion within the jet region.

Inhaling dust can lead to respiratory diseases, and dust accumulation in the workplace can pose fire and explosion hazards. Traditional dust removal nozzles require high water pressure and produce large droplet diameters. The Laval nozzle, utilizing a converging-diverging section to accelerate fluid to supersonic speeds, achieves finer droplets and a more concentrated particle size distribution. However, curved Laval nozzle is different to manufacture. To study the effect of water pressure on the atomization performance of a Linear Laval nozzle, a laser particle analyzer and a camera were used to test the droplet size and atomization angle. These results were compared with numerical analysis. The findings indicate that as the water pressure increases from 0.1 MPa to 0.5 MPa, the dropletsʼ Sauter Mean Diameter (SMD) increases almost linearly. At the same time, the spray angle tends to decrease. Both experimental and numerical analyses show the same trend. At a water pressure of 0.1 MPa, the atomization performance of the Linear Laval nozzle is optimal. Compared to traditional nozzles, the water pressure is significantly reduced, and the D(3,2) droplet diameter is notably smaller. Moreover, the atomization angle is considerably increased. The spray effect has been significantly improved.

In this work, the aging behavior of liquid insulation in transformers using chemically modified refined, bleached, and deodorized palm oil (RBDPO) olein is investigated. The transesterification process is used to modify RBDPO olein to produce palm oil methyl ester (POME), which is used as a base fluid for nanofluid (NF) preparation. The performance of POME with the dispersion of semiconducting titanium oxide (TiO ₂ ) and conducting multi-walled carbon nanotube (MWCNT) nanoparticles (NPs) at different concentrations on the AC breakdown voltage (AC BDV) as insulation in transformers is evaluated for their aging behavior. The accelerated aging was conducted under sealed conditions at a temperature of 130°C for 1000 hours. The results show that incorporating TiO ₂ and MWCNT NPs into POME did not have an adverse effect on the BDV, regardless of the doping concentrations. Notably, POME-based TiO ₂ NFs exhibited the highest AC BDV after thermal aging, specifically at a concentration of 0.05 g/L. Anderson-Darling goodness-of-fit statistics were performed on the experimental data to verify their agreement with the Normal and Weibull distributions.

Swirling gas injection is a well-known technique to improve mass transfer in bubble columns. It can be used to create small bubbles with a high surface area-to-volume ratio, which is beneficial for mass transfer. Swirl gas injection can also be used to create a more uniform bubble size distribution and improve the mixing of gas and liquid in the column. This study aims to determine the impact of swirl gas injection on bubble properties, including bubble shape, size, and velocity. A bubble detection approach has been developed for quick and precise determination of bubble size distributions in gas-liquid systems. Advanced digital image processing, including edge detection and bubble edge recognition, is used in this method. The experiment is conducted in a bubble column at a height of 57 cm and 61 cm. The column had a ring sparger and was made of Plexiglas. Tap water was used as the liquid, while air from an air compressor was utilized as the gas phase. The shape, size, population, and velocity of the bubble are measured using a high-speed digital camera. According to this study, the average bubble size reduced as the impeller speed increased, while the population of bubbles increased when the sparger rotation speed increased from 30 to 150 rpm.

The increasing demand for sustainable energy generation brings a need for tidal current energy resource exploration around the globe. Hydrodynamic modelling is an essential aspect to explore macro tidal sites. In the current research paper, a 2D hydrodynamic model is set up by utilizing the numerical application of Delft3D. The model is validated against the database results and the two macro tidal sites are identified along the coastline of Sarawak, Malaysia. The maximum available kinetic energy flux at the identified location is 0.6 kW/m2, during peak neap tide hours. This stands as a sound justification to have a detailed tidal energy assessment study in this area in future research.

Due to global environmental conditions, the focus of household heating has shifted from fossil fuels towards environmentally friendly and renewable energy sources. Desuperheaters have attracted attention as a domestic provision involving steam-induced direct contact condensation (DCC)to warm the water. The present study is an attempt to investigate the hydrodynamics in the desuperheater vessel experimentally, namely, when the pressurized pulsating steam is injected into the vessel, where the steam jet interacts co-currently with the slow-moving water. Flow visualization showed a circulation region when the pulsating steam was injected into the slow-moving water, and the peaked vorticity corresponded to the steam injection duration of 10–60 s. Sevenhot film anemometers (HFAs) were traversed axially and radially to determine the velocity fluctuations at 0–20 cm from the steam’s nozzle exit. Vortical structures indicated the entrainment of the steam with the surrounding moving water. The circulation regions were thus exhibited in relation to the steam’s injection durations as well as the downstream axial distances of 2 and 15 cm from the nozzle exit, which showed that the core local circulation at 2 cm downstream of the nozzle exit lost 75–79% of its circulation at 15 cm downstream of the nozzle exit.