Search Results (60)

This work uses battery-coupled power electronic converter systems and distributed backstepping controllers to improve the reliability of electrical distribution networks. The motivation is to prevent blackouts such as the 28 April 2025 outage in Spain, Portugal, and the south of France. It is now accepted that a rapid rise in solar power injections caused AC overvoltage above grid code limits, triggering photovoltaic (PV) park disconnections as overvoltage self-protection. This case study considers near-Zero-Energy Buildings (nZEBs) connected to the Madeira Island isolated microgrid, where PV power installation is increasing excessively. The main university facility will be upgraded as an nZEB, using roughly 3000 m² of unshaded rooftops plus coverable parking areas to install PV panels. Optimizing the profits/energy cost ratio, a PV power system of around 560 kW can be planned, and the Battery Storage System (BSS) energy capacity can be estimated. The BSS is connected to the university nZEB via backstepping-controlled multilevel converters to manage PV and BSS, enabling the building to contribute to voltage and frequency regulation. Distributed multilevel converters inject renewable energy into the medium-voltage network, regulating active and reactive power to prevent overvoltages shutting down the PV inverters. This removes sustained overvoltage and maximizes PV penetration while augmenting AC grid reliability and resilience. When there is excess solar power and reactive power is insufficient to reduce voltage, controllers slightly curtail PV active power to eliminate overvoltage, maintaining operation with minimal revenue loss while preventing long interruptions, thereby improving grid reliability and power quality. Full article

Triple-negative breast cancer (TNBC) poses significant therapeutic challenges due to the limited availability of targeted treatment options and the development of resistance to chemotherapy, including doxorubicin (DOX). The objective of this study was to investigate the impact of inhibiting activated pathways in DOX-resistant TNBC and examine the effects on MAPK and PI3K/Akt signaling pathways, cell cycle regulation, and the regulators of the epithelial–mesenchymal transition (EMT) process. Continuous exposure of cells to increasing concentrations of DOX resulted in the selection of resistant cells that exhibited EMT characteristics. We assessed the expression levels of markers related to cell death, survival, mitophagy pathways and EMT using Western blotting and qPCR in both sensitive and resistant cells with activated-pathway inhibitor treatments. Additionally, we demonstrated differences in migration capacity between resistant and sensitive cells with or without inhibitor treatments. It was found that MEK inhibition was less effective than PI3K inhibition in both sensitive and resistant cells. Expression analyses clearly demonstrated that resistant cells exhibited more aggressive behavior, as indicated by EMT- and survival-related gene expressions. The combination of MEK and PI3K inhibitors was more effective in shutting down these signals in both cell types. The ability to induce EMT in DOX-resistant cells revealed that one form of resistance might combine with another, acting as a mediator for cellular switch. Although drug resistance and various inhibitors reduce the proliferative capacity of cells and related parameters, resistance contributes to the acquisition of metastatic characteristics. Full article

The pivotal moment of 23 August 1944 thrust Romania into alliance with the Soviet Union and launched over four decades of communist rule. The Romanian Orthodox Church actively resisted communist ideology, but was swiftly targeted by state oppression. Soviet troops entering Banat executed atrocities, seized property, arrested citizens, and terrorized communities. These actions marked the start of communist domination. A critical review of this era shows that authorities deliberately and systematically dismantled the Church and other Romanian institutions in Banat. Most significantly, they dissolved the Caransebeş Diocese, the principal ecclesiastical authority for Romanians in South Banat. Authorities shut down theological academies in Caransebeș and Timișoara, and forced hierarchs Veniamin Nistor and Vasile Lăzărescu into exile. These actions severely crippled the Church’s role. Collectively, these measures devastated the Banat Church’s religious, educational, and social capacities. Full article

This perspective paper aims to set the stage for current development in the field of energy consumption and environmental impacts in two major digital industries: cryptocurrency mining and artificial intelligence (AI). To better understand current developments, this paper uses a comparative analytical framework of life-cycle assessment principles and high-resolution grid modeling to explore the energy impacts from academic and industry data. On the one hand, while both sectors convert energy into digital value, they operate according to completely different logics, in the sense that cryptocurrencies rely on specialized hardware (application-specific integrated circuits) and seek cheap energy, where they can function as “virtual batteries” for the network, quickly shutting down at peak times, with increasing hardware efficiency. On the other hand, AI is a much more rigid emerging energy consumer, in the sense that it needs high-quality, uninterrupted energy and advanced infrastructure for high-performance Graphics Processing Units (GPUs). The training and inference stages generate massive consumption, difficult to quantify, and AI data centers put great pressure on the electricity grid. In this sense, the transition from mining to AI is limited due to differences in infrastructure, with the only reusable advantage being access to electrical capacity. Regarding competition between the two industries, this dynamic can fragment the energy grid, as AI tends to monopolize quality energy, and how states will manage this imbalance will influence the energy and digital security of the next decade. Full article

Pumped storage power stations (PSPSs) are crucial regulators for accelerating the global energy structure transformation and developing a renewable energy-dominated power system. The sediment entering the reservoirs leads to capacity loss, while the fine-grained sediment carried by water during pumping and power generation can cause cavitation in penstocks and abrasion of turbine blades, which may lead to frequent shutdowns for overhaul. Taking a pumped storage power station as an example, whose lower reservoir is on a sediment-laden river, this study simulates the sediment concentration and its particle size through turbines under different sediment regulation measures. The unit abrasion rate and overhaul cycle are further predicted. The results indicate that the sediment concentration through turbines (SCT) and the suspended sediment transport rate entering the lower reservoir are positively correlated. The higher the SCT, the coarser the sediment particle size through turbines. For the lower reservoir with delta or conical sedimentation patterns, lowering the water level and shutting down pumping during sediment peak processes can free up the effective storage capacity, reduce the SCT by approximately 26%, and extend the overhaul cycle to 1.5 times. The study also systematically introduces a practical and feasible method for predicting SCT and turbine blade abrasion, servicing for the sustainability of PSPSs. Full article

The WieZhou12 oilfield (also known as WZ12 oilfield, the same below) is in urgent need of development using large-scale volumetric fracturing technology since it is a typical complex fault-block oilfield with low porosity, low permeability, and no natural production capacity. To study the fracturing measures with surfactants in offshore oilfields like WZ12, the surfactant fracturing fluid types were experimentally selected based on their effect of decreasing interfacial tension and enhancing matrix wettability. The water cut law and oil displacement efficiency in displacement experiments were also analyzed, according to surfactant type and fluid characteristics. Next, using the numerical simulation software CMG, the study completed the integrated simulation of volumetric fracturing in the “injection–soaking–flowback” process. Finally, some critical parameters were optimized for the block model, including the quantity of injected fluids, the soaking time, and the rate of fluid flowback. The results showed that the most suitable surfactant was 0.5% ammonium lauryl polyether sulfate (ALES), which had a low interfacial tension of 1.7 × 10⁻² mN/m, a contact angle of 20.071° with the core, and a 52% oil displacement efficiency. From the simulations, the suggested production parameters for energy storage fracturing are as follows: a daily injection volume of 600 m³/d, a soaking time of 25 days post fracturing, and a fluid production rate of 270 m³/d. The findings of this study establish a significant theoretical foundation for optimizing surfactant type and provide construction advice for the integrated measure of fracturing, well shut-in, and production in offshore oilfields. Full article

To achieve carbon neutrality in shipping and comply with the IMO’s increasingly stringent environmental regulations, the transition of small and medium-sized workboats to eco-friendly alternatives is an urgent issue. This study quantitatively compares the fuel efficiency and operational fuel cost savings of hybrid propulsion systems based on actual operational data from a buoy maintenance vessel. The methodology comprised four stages: First, measurement equipment was installed on the vessel to collect real-sea data. Second, the collected data were processed to derive specific fuel oil consumption curves and load profiles. Third, fuel consumption models for mechanical and hybrid propulsion systems were developed. The battery capacity of the hybrid models was selected based on actual operational requirements. Performance indicators and economic analyses were conducted for a comparative evaluation. Fourth, simulation results indicated that the hybrid electric system achieves 2.02% fuel savings, translating to annual fuel savings of USD 1053.24 and a corresponding 2.02% CO₂ reduction. The hybrid mechanical system yielded 0.66% savings. These improvements are attributed to a rule-based energy management strategy of operating generators at their optimal efficiency points and shutting down main engines during low-load periods. This study provides empirical evidence supporting Korea’s 2030 eco-friendly public vessel transition plan. Full article

The efficiency of liquid unloading in dewatering wells directly affects the performance of the Liaohe Ma-19 gas storage facility—the first strongly water-flooded depleted reservoir in China converted for storage use. However, existing hydraulic jet pumps often exhibit low liquid-removal efficiency and capacity mismatches with field operating conditions. To address these limitations, a gas-powered negative-pressure pump system was developed based on gas dynamics principles. Using a custom-built flow loop with injection pressures up to 10 MPa and flow rates of 500–1200 m³/h, the effects of backpressure, nozzle-to-throat area ratio, and formation pressure on pump performance were systematically investigated. The results indicate that an optimal nozzle-to-throat area ratio of 0.19 achieves critical gas velocity at the throat, maximizing the negative pressure effect. Compared with conventional hydraulic jet pumps, the gas-driven system reduces start-up pressure by 87% and increases pressure drawdown by over 50%, while eliminating post-shut-in liquid accumulation through the use of compressed gas as the power fluid. This study demonstrates that the proposed system offers an efficient and reliable artificial lift solution for liquid unloading in gas storage operations. Full article

Tight gas reservoirs, as important unconventional natural gas resources, face low recovery rates due to low porosity, low permeability, and strong heterogeneity. CO₂ Storage with Enhanced Gas Recovery (CSEGR) technology combines CO₂ geological storage with natural gas development, providing both economic and environmental benefits. However, the main controlling factors and influence mechanisms remain unclear. This study utilized the PR-EOS to investigate CH₄, CO₂, and natural gas physical properties, established a numerical simulation model considering CO₂ dissolution and geochemical reactions, and explored the influence of injection scheme, injection rate, production rate, and shut-in condition on CO₂ enhanced recovery and storage effectiveness through orthogonal design. Results show that CO₂ exhibits significant differences in compressibility factor, density, and viscosity compared to natural gas, enabling piston-like displacement. Intermittent injection slightly outperforms continuous injection in recovery enhancement, while continuous injection provides greater CO₂ storage capacity. The ranking of the significance of different influencing factors for enhanced oil recovery is as follows: injection rate > production rate > injection scheme > shut-in condition. For the effect of geological storage of CO₂, it is as follows: injection rate > injection scheme > production rate > shut-in condition. During gas injection, supercritical, ionic, and dissolved CO₂ continuously increase while mineral CO₂ decreases, with storage mechanisms dominated by structural and residual trapping. The study provides scientific basis for optimizing CO₂ flooding strategies in tight gas reservoirs. Full article

After an aero-engine shuts down, the high temperature within the core flow path prevents conventional borescope probes from performing immediate internal inspections due to their limited thermal resistance, thereby constraining rapid turnaround capabilities for aircraft. To address this challenge, this study proposes an active cooling strategy using coolant flow to keep the probe within a safe temperature range. Three cooling structures incorporating pressure-drop modules—annular, annular-slit, and round-hole configurations—were designed and numerically investigated to assess the effects of geometric parameters and coolant properties (temperature, pressure, nitrogen mixing ratio) on cooling performance. The results demonstrate that the round-hole structure with a 1.0 mm diameter achieves optimal cooling, maintaining an average probe mirror temperature of 286.2 K under coolant conditions of 285 K and 0.5 MPa. Cooling efficiency exhibits a strong linear negative correlation with coolant temperature, while its relationship with pressure is highly structure-dependent. Nitrogen doping significantly improves the heat transfer capacity of the coolant. The implemented three-stage pressure-drop module performs consistently, with the pressure loss per stage determined solely by the inlet pressure. This study provides valuable insights and a theoretical foundation for the design of high-temperature-resistant borescope equipment capable of operating in the harsh environments of aero-engines. Full article

This study presents the development and validation of an AI-based system for detecting chainsaw sounds, integrated into a fixed-wing VTOL UAV. The system employs a convolutional neural network trained on log-mel spectrograms derived from four sound classes: chainsaw, music, electric drill, and human voices. Initial validation was performed through ground testing. Acoustic data acquisition is optimized during cruise flight, when wing-mounted motors are shut down and the rear motor operates at 40–60% capacity, significantly reducing noise interference. To address residual motor noise, a preprocessing module was developed using reference recordings obtained in an anechoic chamber. Two configurations were tested to capture the motor’s acoustic profile by changing the UAV’s orientation relative to the fixed microphone. The embedded system processes incoming audio in real time, enabling low-latency classification without data transmission. Field experiments confirmed the model’s high precision and robustness under varying flight and environmental conditions. Results validate the feasibility of real-time, onboard acoustic event detection using spectrogram-based deep learning on UAV platforms, and support its applicability for scalable aerial monitoring tasks. Full article

This study introduced and evaluated a new Carbon Nanotube (CNT) sheet-based method for battery temperature management, aimed at enhancing the performance of Li-ion batteries in subzero environments. This method addressed critical challenges such as startup failures, capacity loss, and the poor performance of the Li-ion battery in extreme cold conditions, particularly for industrial applications like forklifts operating at temperatures as low as −30 °C. Without CNT heating, the battery performance dropped significantly in low-temperature environments. At −20 °C, the battery delivered only 63.4% of its capacity, with minimal self-heating. At −30 °C, it failed almost entirely, shutting down after just 45 s. In contrast, CNT heating greatly enhanced performance. The CNT sheet quickly warmed the battery to 0 °C—within 97 s at −20 °C and 141 s at −30 °C—allowing it to recover up to 90% of its capacity. These improvements resulted in enhanced capacity and energy output compared to batteries without CNT heating, which suffered from severe performance losses, including a negligible capacity and energy output under −30 °C. It can be concluded that the CNT sheet-based approach provides superior thermal conductivity, rapid heating, and exceptional energy conversion efficiency, enabling extended battery life and enhanced operational reliability in subzero environments. Its scalability and affordability position it as a transformative innovation for industrial applications reliant on efficient battery performance in extreme cold environments. Full article

Efficient coal grinding is a crucial aspect of the energy and mining industries. However, traditional grinding methods are known to be energy-intensive and cause significant wear on equipment as well as negative environmental impacts due to the release of small particles that can harm air quality and affect human health. In response to these challenges, we are conducting research to develop an electric pulse device for coal grinding. This device will use high-voltage discharges in a liquid medium to create shock waves that selectively destroy coal particles while minimizing mechanical damage. The electric pulse installation consisted of a control unit (for monitoring the operating modes of the installation), a generator (for converting the AC input voltage into DC output voltage), a capacitor (for energy storage), a protection system (for shutting down the installation in cases when a voltage exceeding the set safe operating discharge voltage occurs on the capacitor), a spark gap (forming a gap consisting of two conductive hemispherical electrodes separated by an air gap, designed to form an electric spark between conductors), and an electric pulse grinding device. The input material for each experiment had consistent parameters: the coal particles were diameter 8–10 mm and weighed 400 g. Coal was processed using the electric pulse method with various voltage values, numbers of pulses, capacitor capacities, and pulse frequencies. The yield of the final product depended on these parameters, and effective settings for producing coal powder were identified. The research results demonstrate that a flat metal mesh plate is effective as the negative electrode in the electric pulse grinding device. Full article

The article discusses the application of advanced data mining methods applicable to electricity consumption within a local power system in Poland. This analysis involves power demand. It is aimed at predicting daily demand variations. In such a case, system demand is characterized by high variability over a short period of time, e.g., 24 h. This constitutes a significant issue within a small power grid. It entails effective load programming on a given day and time. Therefore, the authors of the paper suggested employing artificial intelligence to forecast industrial power grid load for successive time intervals of the operation process. Such a solution applied within a power system enables appropriate start-up/shut-down planning, as well as generator operation at a specific capacity in power plants. It thus allows continuous power system (on-line) load demand balancing. Predicting power system load also involves determining moments, e.g., of power plant start-up, transition times to maximum or minimum output, or also the shut-down of such a process. This means ongoing and continuous (automatic) impact on electricity distribution. It significantly reduces carbon dioxide atmospheric emissions and allows zero-emission, e.g., wind, hydro, geothermal, or solar plants to meet current power needs. The issue associated with operating small ‘island’ power systems is a dynamic and rapid change in power demand. This is related to the area-based—‘island’—use’ of available power sources that can only be operated within a specific area. A very important problem occurring within these structurally small grids is the continuous forecasting of load changes and real-time response to power demand (i.e., balancing power demand through in-house or available power sources). Full article

The main tight sandstone gas reservoirs in the Linxing block of the Ordos Basin exhibit a temperature range of 35–60 °C. Under these low-temperature conditions, conventional oxidative gum breakers used in fracturing operations react sluggishly, fail to break the gum completely, and can cause significant reservoir damage. In order to achieve complete breakage of the fracturing fluid and reduce the damage to the fracture and reservoir, active bio-enzyme-enhanced breakers have been incorporated into fracturing fluid formulations, so as to achieve rapid breakage, re-discharge at low temperature, and reduce the contact time between the fracturing fluid and the formation, which is critical for enhancing production efficiency. Based on the preliminary success of bio-enzyme-enhanced fracturing technology, this paper carries out an optimization study of bio-enzyme-enhanced fracturing technology for the low-temperature reservoir in the Ordos Linxing block. The study simulates the temperature recovery of the injected fluids under different reservoir temperatures during the fracturing process, aiming to further optimize the concentration of the bio-enzyme-enhanced fracture breakers in the fracturing phases, and to achieve optimized fracturing technology which is more in line with the temperature environment of the fluids. This can further optimize the concentration of the bio-enzyme breaker added at each fracturing stage, and achieve enhanced breaking in a stepwise manner that is more in line with the fluid temperature environment, thus improving the efficiency and production capacity for subsequent production. The optimized fracturing fluid system, incorporating the tailored concentration of the bio-enzyme breaker, was applied to 54 wells in this block, resulting in about a two-times improvement in production compared to conventional non-optimized methods, with many wells achieving high output. These results demonstrate the strong applicability of the optimized breaker procedure in this geological context. Additionally, this study investigated an optimization model for the well shut-in time during winter operations involving low-temperature fracturing fluids in low-temperature reservoirs, providing a valuable design basis for future production planning. Full article