Search Results (89)

The emergence of electric vehicles (EVs) has brought specific risks, including the possibility of fires or explosions resulting from mechanical, thermal, or electrical failures, which can lead to thermal runaway (TR). There is a great lack of knowledge about how to act safely in this type of fire. This study carried out two full-scale fire experiments on electric vehicles to investigate response strategies to electric vehicle fires caused by thermal runaway. Centro Zaragoza provided technical advice for these tests, so that they could be carried out safely, controlling the risks. This advice has allowed Centro Zaragoza to analyze different response strategies to the fires in electric vehicles caused by thermal runaway. On the other hand, the propagation patterns of thermal runaway fires in electric vehicles were investigated. The early-phase effectiveness of fire blankets and other extinguishing measures was tested, and the temperature distributions inside the vehicle and the type of fire generated were measured. The results showed that fire blankets successfully extinguished flames by cutting off the oxygen supply. These findings contribute to the development of effective strategies for responding to electric vehicle fires, enabling the establishment of good practice for fire suppression in electric vehicles and their batteries. Full article

Extremely powerful flares releasing energy well above ${10}^{32}$ erg are rare compared to the typical manifestations of solar activity, which are already being routinely monitored by the existing Space Weather network—with some level of predictability. However, much less is known about the mechanisms behind such rare events (like the well-documented Carrington event of 1859) or about hypothetical superflares that could exceed current energy estimates by several orders of magnitude. We propose a model based on the nonlinear suppression of turbulent diffusion with increasing magnetic field, which ultimately leads to the random occurrence of regions with a magnetic field amplitude significantly exceeding the magnetic field amplitude in a regular cycle. This is similar to the mechanism of a local “explosion of an overheated boiler”. Such regions can be correlated with flares. In our model, flares have different powers. Full article

With the increasing deployment of DC power systems, particularly in DC distribution systems, there is a growing demand for rapid and effective fault current limiting solutions. Conventional fault current limiters (FCLs) often suffer from limitations in terms of response time, size, and operational complexity. As a solution to these challenges, this paper proposes a hybrid FCL based on a pyro conductor switch (PCS), which combines passive limiting elements with an active switching mechanism. The proposed PCS FCL consists of a pyro fuse, an IGBT switch, a limiting inductor, and a damping resistor. Upon fault detection, the IGBT switch is first turned off to initiate current transfer into the limiting branch. Subsequently, the pyro fuse operates by explosively severing the embedded conductor using a pyrotechnic charge, thereby providing galvanic isolation and reinforcing current commutation into a high-impedance path. This operational characteristic enables effective fault current suppression without requiring complex control or real-time sensing. A detailed analysis using PSCAD/EMTDC simulations was conducted to evaluate the current limiting characteristics under fault conditions, and a prototype was subsequently developed to validate its performance. The simulation results were verified through experimental testing, indicating the limiter’s ability to reduce peak fault current. Furthermore, the results demonstrated that the degree of current limitation can be effectively designed through the selection of appropriate current limiting parameters. This demonstrates that the proposed PCS-based FCL provides a practical and scalable solution for improving protection in DC power distribution systems. Full article

Lithium-ion batteries (LIBs) are widely used as energy storage units in electric vehicles, mobile phones, and other electric devices due to their high voltage, large capacity, and long cycle life. Lithium-ion batteries are prone to thermal runway (TR), resulting in fires and explosions, which can seriously hinder the commercial development of LIBs. A series of safety methods has been studied to prevent TR of LIBs. The safety methods for suppressing TR in LIBs were reviewed, including safety equipment method, material modification method, thermal management method, and cooling method. The mechanism, advantages and disadvantages, and future applications of the TR suppression method are discussed. The effectiveness of the proposed safety method was evaluated through technical analysis and experimental testing, and the inhibitory effects of different safety methods on battery TR were summarized. The future trend of suppressing TR is discussed by summarizing and generalizing existing technologies for suppressing thermal runaway. This study provides a reference for exploring more effective methods to mitigate TR in the future. Full article

To address the research gap in gas blast resistance of composite precast assembled utility tunnels, this study investigates structural damage evolution and the mechanisms influencing parameters through validated numerical simulations. A three-dimensional numerical model, incorporating the Karagozian & Case (K&C) concrete damage model and tie-break contact algorithm, was developed using LS-DYNA. The first validation against composite precast concrete slab explosion tests confirmed the model’s reliability, with displacement peak errors below 10%. The second validation focuses on the blast resistance test conducted on an underground utility tunnel, revealing an error margin of less than 10%. Results indicate that the utility tunnel exhibits a progressive failure mode of “joint cracking-interface damage-midspan cracking” under explosive loads, with stiffness degradation observed in joint regions at a loading pressure of 700 kPa. Increasing the normal strength of the interface to 5 MPa suppresses 90% of interface delamination, whereas completely neglecting interface strength results in a 9.0% increase in midspan displacement. Concrete strength shows minimal impact (<2.5%) on displacement under high loading conditions (≥0.9 MPa), and increasing the reinforcement ratio from 0.44% to 0.56% reduces displacement of the roof slab by 10.5%. These findings of address the research gap in the gas explosion response of composite precast assembled utility tunnels and could have significant implications for enhancing the disaster resistance of urban underground spaces. Full article

This study conducted systematic experimental research on methane safety issues in industrial production environments, with a particular focus on the impacts of high-temperature conditions and complex atmospheres on methane explosion characteristics. The research team designed and constructed a dedicated combustible gas explosion experimental setup, performing in-depth experimental analyses across a broad temperature range from 25 °C to 600 °C. The results demonstrate that elevated temperatures significantly reduced the methane’s lower explosion limit (LEL), with the LEL decreasing to approximately 40% of its room-temperature value at 600 °C. The investigation systematically examined the influence mechanisms of common industrial atmospheric components, including carbon dioxide (CO₂), ammonia (NH₃), oxygen (O₂), and water vapor (H₂O) on methane explosion behavior. Key findings reveal that CO₂ exhibited notable suppression effects, increasing methane’s LEL by approximately 15% per 10% increment in CO₂ concentration. NH₃ demonstrated dual mechanisms, promoting methane explosions at low concentrations (<5%) while inhibiting them at higher concentrations. Increased O₂ concentration significantly expanded the methane’s explosive range, with the LEL decreasing by about 22% when O₂ concentration increased from 21% to 30%. Water vapor manifested differentiated impacts depending on temperature regimes, primarily elevating LEL through dilution effects below 200 °C while reducing LEL via radical reaction promotion above 400 °C. Furthermore, this study reveals synergistic coupling effects between temperature and gas components—for instance, CO₂’s suppression efficacy weakened under high temperatures, whereas NH₃’s promotion effect intensified. These discoveries provide scientific foundations for formulating industrial safety standards, designing explosion-proof equipment, and conducting risk assessments in production processes. Full article

This study investigates the suppression effect of ultrafine CaCO₃ powder on gas explosions through a series of experiments conducted in a medium-scale explosion tube (9.6 m in length) with varying concentrations of ultrafine CaCO₃. The gas explosion suppression concentration was established at 9.5%. The results indicate that, at concentrations of 125 g/m³ and 300 g/m³, ultrafine CaCO₃ powder significantly reduced the flame propagation speed of the gas explosion. Among the concentrations that did not fully suppress the gas explosion, 20 g/m³ effectively mitigated the flame propagation speed and overpressure throughout the entire process. The concentration of 75 g/m³ demonstrated a suppression–promotion–suppression–promotion pattern regarding the flame propagation rate, with significant fluctuations observed throughout the process. While the maximum suppression rate reached 60.9%, the maximum promotion rate was 131.12%. At 10 g/m³, the flame propagation rate initially increased before decreasing, with the most effective suppression observed within the first 6.6 m, where flame propagation suppression increased rapidly from 58.13% to 74.82%, and the peak explosion overpressure was reduced by up to 62.94%. These findings contribute valuable insights for the development of effective gas explosion suppression strategies in mining environments. Full article

In order to ensure the safety of methane/hydrogen, regular SiO₂ powder was modified. Fe(C₅H₅)₂/SiO₂ composite dry powder (CDP) was selected as the explosion-suppression material. Explosion-suppression experiments and numerical simulations were adopted to investigate the inhibition effect of 0% (${\mathit{X}}_{{\mathrm{H}}_2}$ = 0%) and 20% (${\mathit{X}}_{{\mathrm{H}}_2}$ = 20%) hydrogen doping ratios. The flame structure, flame propagation speed, and maximum explosion pressure are depicted to compare the inhibition effect of different mass fractions (X_Fe(C5H5)2 = 0–6%). The results showed that CDP significantly reduced the flame propagation velocity and maximum explosion pressure of ${\mathit{X}}_{{\mathrm{H}}_2}$ = 0%. The best effect was observed when 6% Fe(C₅H₅)₂ was added, with the velocity reduced to 9.241 m/s. The maximum explosion pressure was reduced to 0.518 MPa, and the effect was relatively weak for ${\mathit{X}}_{{\mathrm{H}}_2}$ = 20%, with the maximum pressure reduced to 0.525 MPa. In addition, the key radical production and temperature sensitivity showed that Fe(C₅H₅)₂ altered the molar fractions of the major species and increased the consumption of •H, •O, and •OH. As the mass fraction of Fe(C₅H₅)₂ increased, the steady-state concentrations of •H, •O, and •OH in the system showed a significant decreasing trend. This phenomenon originated from the two-step synergistic mechanism of Fe(C₅H₅)₂ inhibiting radical generation and accelerating radical consumption. This study provides insight into the process of Fe(C₅H₅)₂/SiO₂ composite dry powder inhibition and renders theoretical guidance for the explosion protection of methane/hydrogen. Full article

As CMOS technology continues to downsize to the nanometer range, the exponential growth predicted by Moore’s Law has been significantly decelerated. Doubling chip density in the two-dimensional domain will no longer be feasible without further device downsizing. Meanwhile, emerging new device technologies, which may be incompatible with the mainstream CMOS technology, offer potential performance enhancements for system integration and could be options for a More-than-Moore system. Additionally, the explosive growth of artificial intelligence (AI) demands ever-high computing power and energy-efficient computing platforms. Heterogeneous multi-chip integration, which combines diverse components or a larger number of functional blocks with different process technologies and materials into compact 3D systems, has emerged as a critical pathway to overcome the performance limitations of monolithic integrated circuits (ICs), such as limited process/material options, low yield, and multifunctional design complexity. Furthermore, it sustains Moore’s Law progression for a further smaller footprint and higher integration density, and it has become pivotal for “More-than-Moore” strategies in the next CMOS technology revolution. This approach is also crucial for sustaining computational advancements with low-power dissipation and low-latency interconnects in the coming decades. The key techniques for heterogeneous wafer-to-wafer bonding involve both copper-to-copper (Cu-Cu) and dielectric-to-dielectric bonding. This review provides a comprehensive comparison of recent advancements in Cu-Cu bonding techniques. Major issues, such as plasma treatment to activate bonding surfaces, passivation to suppress oxidation, Cu geometry, and microstructure optimization to enhance interface diffusion and regrowth, and the use of polymers as dielectrics to mitigate contamination and wafer warpage, as well as pitch size scaling, are discussed in detail. Full article

It is well known that the safety concerns surrounding lithium-ion batteries (LIBs), such as fire and explosion, are currently a bottleneck problem for the large-scale usage of energy storage power stations. The study of water-based fire-extinguishing agents used for LIBs is a promising direction. How to choose a suitable water-based fire-extinguishing agent is a significant scientific problem. In this study, a comprehensive evaluation model, including four primary indexes and eleven secondary indexes was established, which was used in the scenario of an electrochemical energy storage power station. The model is only suitable for assessing water-based fire extinguishing for suppressing lithium iron phosphate battery fire. Based on the comprehensive evaluation index system and extinguishing experiment data, the analytic hierarchy process (AHP) combined with fuzzy TOPSIS was used to evaluate the performances of the three kinds of water-based fire-extinguishing agents. According to the results of the fuzzy binary contrast method, the three kinds of fire-extinguishing agents could be ranked as follows: YS1000 > F-500 additive > pure water. The study provided a method for choosing and preparing a suitable fire-extinguishing agent for lithium iron phosphate batteries. Full article

The explosive demand for high-performance secondary power sources in artificial intelligence (AI) has brought significant opportunities for low-voltage GaN devices. This paper focuses on research on high-efficiency and high-reliability low-voltage p-GaN gate HEMTs with a gate–drain distance, L_GD, of 1 to 3 μm in our pilot line, manufactured on 6-inch Si using a CMOS-compatible process, with extraordinary wafer-level uniformity. Specifically, these fabricated p-GaN gate HEMTs with an L_GD of 1.5 μm demonstrate a blocking voltage of over 180 V and a high V_TH of 1.6 V and exhibit a low R_ON of 2.8 Ω·mm. It is found that device structure optimization can significantly enhance device reliability. That is, through the dedicated optimization of source field plate structure and interlayer dielectric (ILD) thickness, the dynamic ON-resistance, R_ON, degradation of devices with an L_GD of 1.5 µm was successfully suppressed from 60% to 20%, and the V_TH shift was significantly reduced from 1.1 to 0.5 V. Further, the devices also passed preliminary gate bias stress and high-voltage OFF-state stress tests, providing guidance for preparing high-performance, low-voltage p-GaN gate HEMTs in the future. Full article

Illegal, unreported, and unregulated (IUU) fishing significantly threatens marine ecosystems, disrupts the ecological balance of the oceans, and poses serious challenges to global fisheries management. This contribution presents the efficacy of China’s summer fishing moratorium using BeiDou vessel monitoring system (VMS) data from 2805 fishing vessels in the East China Sea and Yellow Sea, integrated with a deep learning framework for spatiotemporal analysis. A preprocessing protocol addressing multidimensional noise in raw VMS datasets was developed, incorporating velocity normalization and gap filling to ensure data reliability. The CNN-BiLSTM hybrid model emerged as optimal for fishing behavior classification, achieving 89.98% accuracy and an 87.72% F1 score through synergistic spatiotemporal feature extraction. Spatial analysis revealed significant policy-driven reductions in fishing intensity during the moratorium (May–August), with hotspot areas suppressed to sporadic coastal distributions. However, concentrated vessel activity in Zhejiang’s nearshore waters suggested potential illegal fishing. Post-moratorium, fishing hotspots expanded explosively, peaking in October and clustering in Yushan, Zhoushan, and Yangtze River estuary fishing grounds. Quarterly patterns identified autumn–winter 2021 as peak fishing seasons, with hotspots covering >80% of East China Sea grounds. The framework enables real-time fishing state detection and adaptive spatial management via dynamic closure policies. The findings underscore the need for strengthened surveillance during moratoriums and post-ban catch regulation to mitigate overfishing risks. Full article

This study enhanced the performance of gray cast iron through the precise control of the partial austenitizing temperature combined with an isothermal quenching process. The study investigated the effects of three austenitizing temperatures, namely 810 °C, 850 °C, and 900 °C, on the microstructure and mechanical properties of gray cast iron. With the increase in austenitizing temperature, the transformation of pearlite to ausferrite was promoted, and the ausferrite content increased from 8.0% at 810 °C to 91.2% at 900 °C. Mechanical property tests showed that the specimen treated at 850 °C had the best comprehensive performance. Its tensile strength reached 332 MPa, an increase of 78.6% compared with the as-cast state. The elongation increased by 51.8%, and the wear depth under a 20 N load decreased from 250 μm to 2 μm. Specimens with a high ausferrite content exhibited stable low-friction characteristics due to the uniform hardness and the suppression of adhesive wear. However, an excessively high austenitizing temperature of 900 °C would lead to an increase in residual stress in the casting and deformation of the graphite structure, reducing the wear resistance. Under the established austenitizing temperature conditions, this study explored the relevant mechanisms for the performance improvement of gray cast iron by means of various testing methods, providing a theoretical basis and process reference for optimizing the material performance of explosion-proof equipment under harsh mining conditions. Full article

In terms of rockburst control technology, it is generally believed that optimizing the section design and adopting the step method can effectively suppress the occurrence of rockburst, but there is no literature to explain the reasons for adopting this method from the experimental point of view. In addition, compared with the application of support, this method can achieve the effect of not increasing the construction process, not affecting the progress of the project and reducing the project cost. In view of this, the Gaoloushan deep-buried tunnel with rockburst was taken as the research object in this paper. Firstly, the excavation scheme based on the step method was proposed, and its explosion-proof effect was verified again. The experimental results showed that the step method could be essentially regarded as the transformation of surrounding rock by reasonably distributing explosives and reducing the working section. The beneficial effects of this method were as follows: the release intensity of absolute energy was slowed down, the way of energy release was changed; the stress condition of surrounding rock was improved; the path of the continuous supplement of strain energy in the original rockburst area was cut off; and the energy accumulation degree of surrounding rock was reduced, so that the accumulated energy in the rock mass did not exceed its energy storage limit at the location where the rockburst should have occurred. The reduced high energy was released in an orderly manner and induced the rock failure process, forming a fracture zone and a plastic zone. In the process of expansion, the fracture zone and plastic zone further reduced the stress concentration of the surrounding rock and deteriorated the mechanical properties of the surrounding rock. The stress concentration zone was transferred to the deeper surrounding rock outside the unloading relaxation zone, and part of the elastic energy accumulated in the surrounding rock was released. The strain energy could be distributed and dissipated, and the effect of energy safety and slow release was achieved. Full article

This study investigated the inhibitory effect and mechanism of modified ultrafine ABC powder on the explosion of a methane (CH₄)/coal dust mixed system. Through experiments, it was found that the addition of ABC powder significantly weakened the deflagration characteristics of the CH₄/coal dust mixture system. During decomposition, heat was absorbed to generate ammonia and phosphoric acid. Inert gases such as CO₂ and water vapor produced during decomposition could dilute the oxygen concentration. Phosphate ions produced during the decomposition of ammonium phosphate would bind with free radicals during combustion, reducing their reactivity. The explosion reaction was suppressed through a dual mechanism of physical cooling and chemical consumption of free radicals. The experimental results showed that the weight loss rate of modified ABC powder was 49% at 800 °C, while the weight loss rate of unmodified ABC powder was 78%. The modified ABC powder had better thermal stability and could absorb more heat at high temperatures, further suppressing explosive reactions. This study provides a new modification scheme for explosion suppressants for coal mine safety, which has important theoretical and practical application value. Full article