Search

Electrothermal instability and its effect on the uniformity of discharge channels during underwater electrical wire explosions at different energy deposition rates have been investigated. According to the liquid–vapor transition mechanism, we classified underwater electrical explosion into "phase explosion mode" and "supercritical mode." Two sets of experiments corresponding to the two modes were conducted, and the exploding wires were observed by a shadow imaging system. Results showed that a bamboo-shaped discharge channel was formed in the phase explosion mode, whereas the discharge channel in the supercritical mode was a uniform cylinder. Self-consistent magnetohydrodynamic simulation results indicated that exploding wires transfer into liquid–vapor coexistence phase in the phase explosion mode, accompanied by a rapid increase in the density perturbation and the formation of bamboo-shaped structures. Moreover, a small perturbation model was derived to analyze the electrothermal instability in different thermodynamic states. It was indicated that the density perturbation is easier to grow in the liquid–vapor coexistence state than the supercritical state, which provides a theoretical explanation for the differences between the two electrical explosion modes. [ABSTRACT FROM AUTHOR]

Tungsten carbides are important materials used in ceramic cements, machining tools, catalysts, sensors, and for hydrogen generation. Bulk W–C structures are highly complex; fundamental fully carburized WC and semi-carburized W 2 C are accompanied by structural transitions depending on the composition and temperature. The relationship between the structures, compositions, and temperatures is summarized in the W–C phase diagram. However, the high-temperature, stable, and single-crystalline nanoparticles related to the WC 1-x and W 2 C phases formed via energetic reactions accompanied by rapid cooling rates are not easy to determine considering the bulk phase diagram, and lead to fundamental questions regarding the origin of the nanophases. In this study, we propose a draft for the W–C nanophase diagram composed of the surface and gas-phase WC, WC 1-x , and W 2 C nanophases according to the composition and temperature. The model undergoes the process of a vapor–nanoliquid–nanophase starting from the gas-phase nucleation induced by an extremely high-temperature electrical explosion. In addition, the high-temperature reactivity and quenched nanophase, including its unique nanostructure, are related to the post-melt rheology, physical morphology, and steric hindrance of the solid matrix during an electrical explosion. [ABSTRACT FROM AUTHOR]

Introduction Modern warfare operations are volatile, highly complex environments, placing immense physiological, psychological, and cognitive demands on the warfighter. To maximize cognitive performance and warfighter resilience and readiness, training must address psychological stress to enhance performance. Resilience in the face of adversity is fundamentally rooted in an individual's psychophysiological stress response and optimized through decreased susceptibility to the negative impact of trauma exposure. The current project aims to optimize warfighter expertise, resilience, adaptability, and performance by utilizing a validated Full Dive Virtual Reality (FDVR) training platform to provide high-fidelity, safe, and scalable, controlled stress exposure in highly realistic simulated training scenarios with the most advanced, immersive technology available. Materials and Methods Following Institutional Review Board approval and consent, 2 operators were fitted with high-fidelity virtual reality headsets with hand and eye tracking, full-body haptic feedback suits, a 360° omnidirectional treadmill, and Food and Drug Administration (FDA) cleared biometric monitors. Following acclimation, operators were placed in an industrial fire scenario and instructed to respond as a firefighter and paramedic, to search for and resuscitate any casualties, extinguish the fire, and exfiltrate safely. Following initial acclimation and after each demonstration (n  = 2), 3 semistructured interviews asked operators their perceptions and experiences related to FDVR, focusing on usability, feasibility, and safety. Biometric data were continuously recorded using the Caretaker Medical VitalStream. Results Proof-of-concept (POC) testing proved that the FDVR training platform is usable, safe, and feasible. It creates an immersive environment with physiological responses to mimic realistic Mass Casualty Events (MCEs). Using a case study approach, transcript data were analyzed using thematic analysis. Three major themes emerged: Sensory deficits reduced realism, but sensory feedback improved fidelity, vestibular discord affected the virtual reality experience but only when the system did not respond naturally to operator movement after acclimation, and movement accommodations were made by operators to enhance usability, especially for fine motor movements. Biometric data analysis correlated timestamps from the VitalStream unit with operator responses to stress-inducing events (i.e. explosions, fires, and a deceased victim). Both operators exhibited significant physiological responses, including elevated heart rate, systolic blood pressure, and mean arterial pressure, particularly following explosions, encountering fire, and encountering the deceased victim within the training environment. Conclusions The FDVR training platform overcomes the obstacles of in-person simulation training and provides the closest to real-life experience available. It will allow warfighters to train with their teams in immersive environments that replicate the conditions in which they are expected to perform their duties. The POC demonstrated that physiological responses can be mapped to scenario events to allow tracking of stress responses, cognitive load, as well as performance, and decision-making of the warfighter. The POC only involved 2 operators, but served to prove that the platform was safe and effective. Future testing plans to include 200 warfighters in operational teams of 10 to 12 to further validate the training effectiveness of the FDVR platform. [ABSTRACT FROM AUTHOR]

A controlled fragmentation method, by deep laser melting, for a multi-purpose projectile (penetrator) is presented, using a full-sized projectile with 1100 mm long, 148 mm diameter, and 17.8 mm wall thickness. Effects on penetration and fragmentation performance, for various laser melting parameters, are explored through penetration and fragmentation field tests. It is shown that it is possible to attain an optimal local microstructure, in the melted regions, that ensures a pre-defined fragmentation pattern upon explosion without compromising on the penetration capabilities. [ABSTRACT FROM AUTHOR]

• The 2022 Tonga eruption confirmed that explosions can produce air-driven tsunamis • Lamb waves from large explosions are one way to generate and drive global tsunamis • Airbursts from comets and asteroids can produce tsunamis by atmospheric coupling • Several mechanisms are proposed for air-driven tsunami generation and amplification • Impact plume collapse, vortices, and steam blowoff are hypothetical tsunami sources [ABSTRACT FROM AUTHOR]

Online quantitative safety monitoring is the key technology for ensuring the operational safety of the automatic train protection (ATP) system for the future advanced train control system. However, the traditional formal verification method can only deal with the system of small scale since these verification algorithms exhaustively search all executable paths of formal models. Especially for the formal models with uncertain parameters, the problem of memory overflow will occur due to the state space explosion, which makes verification algorithms fail to converge. To solve this problem, an intelligent quantitative safety monitoring approach is proposed by integrating the probabilistic model checking method (PMCM) with neural network in this paper. To begin with, the instantiated continuous-time Markov Chains model is verified by PMCM offline. Then, the neural network is constructed and optimized based on the offline verification results. The quantitative safety boundaries (QSBs) for all quantitative safety levels are also computed by the designed algorithm. Furthermore, hierarchical iterative evaluation method is applied to efficiently evaluate the reliability performance of the ATP online. Finally, the quantitative safety level of ATP or its subsystem will be determined by both reliability performance and the previous QSBs or the neural network online. [ABSTRACT FROM AUTHOR]

This study investigates the effects of trifluoromethane (CHF 3) and pentafluoroethane (C 2 HF 5) content on maximum explosion overpressure and maximum rate of pressure rise by changing the equivalence ratio. Then, the critical content of hydrogen explosion inhibition is measured. The inhibition and enhancement mechanisms are analyzed using thermodynamics and reaction kinetics. The results indicate that both sub-inhibitory CHF 3 and C 2 HF 5 enhance hydrogen explosion on the lean and stoichiometric sides, and C 2 HF 5 exhibits stronger enhancement. As the equivalence ratio increases, CHF 3 and C 2 HF 5 directly reduce the maximum explosion overpressure, while C 2 HF 5 shows stronger inhibition. The maximum rate of pressure rise of different equivalence ratios decreases directly with increasing CHF 3 and C 2 HF 5 content. For the same equivalence ratio, the critical content of explosion inhibition of C 2 HF 5 is lower than that of CHF 3. Additionally, R31, R829, R927, and R944 contribute to explosion enhancement by consuming CO, producing [H], or releasing heat, while R824, R830, and R861 for CHF 3 as well as R830, R988, R1097, and R1099 for C 2 HF 5 inhibit hydrogen explosion intensity. • CHF 3 and C 2 HF 5 enhance hydrogen explosions on the lean side. • Production of CO is related to the explosion enhancement caused by CHF 3 and C 2 HF 5. • Critical content of hydrogen explosion inhibition of C 2 HF 5 is lower than that of CHF 3. [ABSTRACT FROM AUTHOR]

The inorganic water-based non-expanding fireproof coating was taked as the research object, and the coating thickness as the main influencing factor, the thermal response tests of liquefied petroleum gas tanks were conducted in a pool fire environment. The wall temperature response, damage time, and failure mode of storage tanks after spray fireproof coatings were studied in pool fire environments. The results show that the inorganic water-based non-expansion fireproof coatings have a significant delayed effect on the explosion time of storage tanks under fire action. For civilian liquefied petroleum gas storage tanks, when the filling level is the same, the tank which coating thickness is 2 cm is 6.91 times that of bare tanks in a pool fire environment, the tank which coating thickness is 3 cm is 1.20 times that of the tank which coating thickness is 2 cm, and the tank which coating thickness is 4 cm is 1.05 times that of the tank which coating thickness is 3 cm. The delayed effect of increasing coating thickness on the damage time of storage tanks in a pool fire environment gradually decreases, so it is suggest that to the coating thickness of 3 cm is suitable for storage tank. The research results have certain significance for the safety protection application of storage tanks in a pool fire environment and the study of fireproof coating. [ABSTRACT FROM AUTHOR]

In this paper, the evolution of an explosion of hydrogen/ammonia/air flames is studied by experiments and numerical simulations. A two-dimensional (2D) model is utilized, employing the detached eddy simulation (DES) method along with the thickened flame model. Stoichiometric hydrogen/ammonia/air with ∂ = 25% and 50% (ammonia blending ratio in fuel) is considered. The results indicate that the numerical simulations accurately replicate the experimental findings. Both the experimental observations and numerical simulations reveal the formation process of the "tulip" flame. With increasing ∂, both the flame front speed and overpressure decrease. A change in ∂ can alter the contribution of intermediate reactions, thereby influencing the explosion behavior. • The explosion behavior of ammonia/hydrogen/air was investigated. • A detached eddy simulation with a thickened flame model is employed. • The 2D simulation can accurately predict the explosion of ammonia/hydrogen/air. • The effect of the ammonia blending ratio on the explosion reaction kinetics is analyzed. [ABSTRACT FROM AUTHOR]

As a new type of energy, hydrogen-enriched methane mixed fuel has a high risk of deflagration in the application process. In order to better understand the deflagration and inhibition characteristics of hydrogen-enriched methane fuel, the effect of potassium salt modified dry water material (DW) on the deflagration characteristics of hydrogen-enriched methane fuel was studied by 20 L spherical explosive apparatus, combined with pyrolysis characteristics and kinetic model. The results show that when the addition of different modifier concentrations, it can be divided into three types: small curvature, medium curvature and large curvature according to the change of pressure rising rate. With the increase of the proportion of potassium salt modifiers, the number of areas with small curvature is gradually increasing, the number of large curvature is gradually decreasing, and the number of medium curvature is almost unchanged. When the proportion of potassium salt modifier is 15% and ϕ ≤ 0.7, all enter the area below the medium curvature. When the addition of different modifiers, 15%KCl-DW has the best inhibition effect on P max and (dP/dt) max , while CH 3 COOK-DW and K 2 CO 3 -DW have better inhibition effect on Δ t 2 and Δ t 2. In general, when the hydrogen addition ratio is less than 70%, the addition of inhibitors can significantly reduce the explosion intensity. In terms of inhibition mechanism, we established the decomposition model of potassium salt modified dry water and found that potassium salt modified dry water will produce a large amount of gaseous K and KOH in the explosion system. And gaseous K and KOH will catalyze each other and combine with H and OH to form stable H 2 O, which significantly reduces the mass fraction of H and OH radicals in the chain reaction. The results of this paper provide a theoretical basis for the safe use of hydrogen-enriched methane fuel and the research and development of explosion emergency prevention and control technology. • The explosion suppression of potassium salt modified dry water on H 2 /CH 4 was studied. • The hierarchical inhibition model of H 2 /CH 4 explosion by dry water was defined. • Particle swarm optimization is adopted to optimize the decomposition parameters of DW. • Suppression mechanism of potassium salt modified dry water was analyzed. [ABSTRACT FROM AUTHOR]

This study explores the dynamic evolution of the Hunga Volcano in the Kingdom of Tonga and covers two volcanic unrests, focusing on the creation and subsequent disappearance of a new island between Hunga Tonga (HT) and Hunga Ha'apai (HH) between 2013 and 2023. The island expanded in 2015 and vanished in January 2022 due to a massive eruption (VEI = 6), featuring a 57 km high volcanic cloud and generating multiple tsunamis that caused damage across the Pacific Ocean. Utilizing remote sensing techniques, including multispectral imaging from Sentinel 2, Landsat 8-9, and synthetic aperture radar (SAR) imaging from Sentinel 1, the research employs a supervised random forest classification algorithm to individuate the changing subaerial surface area of the volcano. This approach documents size variations in the islands, particularly during weeks surrounding two volcanic unrests. The classifier, trained on nearly cloud-free multispectral images, automatically delineates surface area changes over the years. The temporal resolution of area change, limited to images with less than 5% cloudiness, encompasses about 50% of Landsat and 20% of Sentinel 2 images between 2013 and 2023, selected from 739 available images. The multispectral observations are complemented by 215 Sentinel 1 SAR images, penetrating clouds, though with limited bands. Despite higher noise, the classifier on Sentinel 1 successfully distinguishes land from ocean. Sentinel 1 observations, starting in 2014, cover the volcano unrest of 2014/2015. Earth Engine, a cloud computing data facility, is used for processing. Analysis indicates a slight decrease in the area change post-2015 island formation and identifies the disappearance of the island bridge connecting HT and HH, along with two smaller islands south of HT and HH in 2022. The 2022 explosion is preceded by an increase in island area in the weeks before the eruption. Global satellite coverage could automatically detect changes in oceanic areas and distinguish water from new volcanic islands, offering a means of identifying volcanic unrests and documenting their evolution. [ABSTRACT FROM AUTHOR]

To study the flame propagating characteristic and its coupling effect with other parameters in the LPG pipeline, a typical pipeline model with two equal‐length branches perpendicular to each other is designed for experiment and simulation. Then, gas explosion scenarios are experimentally tested and numerically simulated, which is followed by the analysis of flame shape changing with time and peak temperature changing with space. Results show that when passing through the bifurcation, flame propagates to vertical branch B in a sharp knife shape affected by the strong vortex, reflected airflow, and compressed pressure wave in the pipeline with a diameter of 0.125 m. At the monitoring point that is 0.4 m away from the bifurcation point, the peak temperature of the vertical branch B is 57.87% bigger than that of the horizontal branch C, and its arrival time is 80% longer than that of the horizontal branch C, due to the existence of flame in vertical branch B. What's more, in both branches, the coupling results between peak temperature and peak velocity agree very well with the growth function, while the coupling results between peak temperature and peak pressure agree well with the decay function, providing aids to the optimal layout design of industrial pipeline branches as well as to the explosion suppression measures. [ABSTRACT FROM AUTHOR]

Explosion risks in confined spaces hinder the widespread use of hydrogen fuel cell vehicles. This study investigates the consequences of hydrogen leakage and explosion accidents from fuel cell vehicles parked in underground garages. Results indicated that downward leaks generate a larger flammable gas cloud size, peak value of V Q8 , and areas of danger 3, 1.2, and 2 more times than upward leaks. Meanwhile, upward leaks result in more extensive damage to steel structures and glass. Flammable gas cloud continuous accumulation occurs between beams owing to parking near a wall, whereas the flammable gas cloud maximum extent decreases by half upon parking adjacent to side walls. However, the radius of burns and minor injuries does not vary with parking position. Compared to a single-vehicle situation, multiple surrounding vehicles considerably expand the range of flammable gas clouds and burn hazard area with increases of 57.9% and 53%, respectively. [Display omitted] • The study investigated hydrogen diffusion in a parking garage with beams and examined flame evolution. • Hazard radius for burns resulting from downward leakage was twice the upward leakage. • Walls reduced the maximum spread range of flammable gas clouds by half. • Nearby vehicles increase flammable gas cloud and burn hazard area by over 50%. [ABSTRACT FROM AUTHOR]

This study conducted various explosion experiments under different porous obstacle conditions of blockage ratio (BR) and void fraction (Φ f). The impact of porous obstacle on flame propagation velocity (v) and peak overpressure (P op) were analyzed. The results indicate that an increase in the BR enhances explosion pressure near the blockage area for both porous and non-porous obstacles. However, it also increases the downstream pressure decline gradient. An increase in the Φ f weakens the hindrance of porous obstacle on the flame propagation, allowing more flame to pass through the internal void channels of obstacles, thus delaying the downstream pressure decay. Compared to non-porous obstacles, gas explosions disturbed by porous obstacles with both high BR (BR＞75%) and high Φ f (Φ f ＞0.55) exhibit a lower downstream pressure decline gradient and a longer positive pressure duration. As a result, the explosion can produce a broader range of destruction. • The impact of porous and non-porous obstacles on flames was compared. • The propagation stability of flame gradually reduces with an increasing BR. • Increasing BR results in the forward shift of the maximum P op point. • Increasing V f tends to delay downstream explosion pressure decline. • Porous obstacles can amplify the destructive range of explosion. [ABSTRACT FROM AUTHOR]

By generalizing a criterion of Mufa Chen for Markov jump processes, we establish the necessary and sufficient conditions for the extinction, explosion and coming down from infinity of a continuous-state nonlinear Neveu's branching process. [ABSTRACT FROM AUTHOR]

We consider 1‐D thermal explosion of a compressible micropolar real gas, assuming that the initial density and temperature are bounded from below with a positive constant and that the initial data are sufficiently smooth. The starting problem is transformed into the Lagrangian description on the spatial domain ]0,1[$$ \left]0,1\right[ $$ and contains homogeneous boundary conditions. In this work, we prove that our problem has a generalized solution for any time interval [0,T],T∈R+$$ \left[0,T\right],T\in {\mathbf{R}}^{+} $$. The proof is based on the local existence theorem and the extension principle. [ABSTRACT FROM AUTHOR]

Calculating the parameters of the ground shock induced by an underground explosion is a complex energy coupling problem. It is difficult to establish a unified ground shock coupling law from limited test data. This paper summarizes the research results obtained at home and abroad and systematically analyzes the coupling mechanism of craters formed by an underground explosion and the ground shock. The differences between the concepts of "closed-explosion critical depth" and "equivalent closed-explosion critical depth" are clearly explained. The spreading of the ground shock energy is attributed to the explosive expansion of the air cavity, revealing a linear relationship between the volume of the cavity region (or the volume of the crack region) and the ground shock energy associated with the underground explosion. The proportionality factor is related to the mechanical properties of the medium and is independent of the magnitude of the explosion equivalent. Based on this, a theoretical calculation formula and conversion method for the ground shock coupling coefficient were established. Explosion tests were conducted in clay and Plexiglass under varying burial depths. The test results were consistent with the theoretically calculated results. Our study provides a theoretical basis for the design of explosion-resistant structures in underground engineering. [ABSTRACT FROM AUTHOR]

The active ingredients extracted from plant materials play an important role in human life and health, and the extraction is a critical step in the preparation of them. It is necessary to develop a sustainable and green extraction. Steam explosion pretreatment enhanced extraction is a higher efficiency, lower equipment investment, less hazardous chemicals and environment-friendly technique, which has been widely used to extract active ingredients from various plant materials. In this paper, current progress and future prospects of steam explosion pretreatment enhanced extraction are overviewed. The equipment, operating steps, strengthening mechanism, critical process factors are comprehensively introduced. Furthermore, recent applications and comparisons with other techniques are discussed in depth. Finally, the future development trends are prospected. The current results show that steam explosion pretreatment enhanced extraction has the advantage of high efficiency. Moreover, steam explosion is simple in equipment, and easy to operate. In conclusion, steam explosion pretreatment can be effectively used to enhance the extraction of active ingredients from plant materials. [ABSTRACT FROM AUTHOR]

A unified and modular falsification-aware single-succedent Gentzen-style framework is introduced for classical, paradefinite, paraconsistent, and paracomplete logics. This framework is composed of two special inference rules, referred to as the rules of explosion and excluded middle, which correspond to the principle of explosion and the law of excluded middle, respectively. Similar to the cut rule in Gentzen's LK for classical logic, these rules are admissible in cut-free LK. A falsification-aware single-succedent Gentzen-style sequent calculus fsCL for classical logic is formalized based on the proposed framework. The calculus fsCL is obtained from the existing falsification-aware single-succedent Gentzen-style sequent calculus GN4 for Nelson's paradefinite (or paraconsistent) four-valued logic N4 by adding the rules of explosion and excluded middle. A falsification-aware single-succedent Gentzen-style sequent calculus GN3 for Nelson's paracomplete three-valued logic N3 is also obtained from GN4 by adding the rule of explosion. The cut-elimination theorems for fsCL, GN3, and some of their neighbors as well as the Glivenko theorem for fsCL are proved. [ABSTRACT FROM AUTHOR]

Recent geophysical studies have highlighted the potential utility of integrating both seismic and infrasound data to improve source characterization and event discrimination efforts. However, the influence of each of these data types within an integrated framework is not yet well‐understood by the geophysical community. To help elucidate the role of each data type within a merged structure, we develop a neural network which fuses seismic and infrasound array data via a gated multimodal unit for earthquake‐explosion discrimination within the Korean Peninsula. Model performance is compared before and after adding the infrasound branch. We find that the seismoacoustic model outperforms the seismic model, with the majority of the improvements stemming from the explosions class. The influence of infrasound is quantified by analyzing gated multimodal activations. Results indicate that the model relies comparatively more on the infrasound branch to correct seismic predictions. Plain Language Summary: Earthquakes and explosions can produce energy that travel as waves through the ground, seismic, and the air, infrasound. As these waves travel to the station where they are detected, they can be changed so drastically by the medium that it makes it difficult to determine what caused them. In these instances, it has been shown that using both seismic and infrasound data works better to characterize an event than using them independent of one another. However, due to the differences in how the air and ground influence the movement of energy, it is not well‐known how these types of data work in unison to give us more information about an event. In this study, we use a machine learning model trained on both seismic and infrasound data to help us better understand how they can be used together to determine their source. Key Points: Discrimination performance within the Korean Peninsula is improved after fusing seismoacoustic data within a deep learning architectureNeural network framework provides insight into how information in multimodal data combine to distinguish between different event types [ABSTRACT FROM AUTHOR]

ABSTRACT The determination of flash points is a critical aspect of chemical safety, essential for assessing explosion hazards and fire risks associated with flammable solutions. With the advent of new chemical blends and the increasing complexity of chemical waste management, the need for accurate and reliable flash point prediction methods has become more pronounced. This study introduces a novel predictive approach using Bayesian kernel machine regression (BKMR) with Gaussian process priors, designed to meet the growing demand for precise flash point estimation in the context of chemical safety. The BKMR model, underpinned by Bayesian statistics, offers a comprehensive framework that not only quantifies prediction uncertainty but also enhances interpretability amidst experimental data variability. Our comparative analysis reveals that BKMR surpasses traditional predictive models, including support vector machines, kernel ridge regression, and Gaussian process regression, in terms of accuracy and reliability across multiple metrics. By elucidating the intricate interactions between molecular features and flash point properties, the BKMR model provides profound insights into the chemical dynamics that influence flash point determinations. This study signifies a methodological leap in flash point prediction, offering a valuable tool for chemical safety analysis and contributing to the development of safer chemical handling and storage practices. [ABSTRACT FROM AUTHOR]

Suzaku X-ray observations of the Type Ia supernova remnant (SNR) 3C 397 discovered exceptionally high mass ratios of Mn/Fe, Ni/Fe, and Cr/Fe, consistent with a near M Ch progenitor white dwarf (WD). The Suzaku observations have established 3C 397 as our best candidate for a near- M Ch SNR Ia, and opened the way to address additional outstanding questions about the origin and explosion mechanism of these transients. In particular, subsequent XMM–Newton observations revealed an unusually clumpy distribution of iron group elemental (IGE) abundances within the ejecta of 3C 397. In this paper, we undertake a suite of two-dimensional hydrodynamical models, varying both the explosion mechanism – either deflagration-to-detonation (DDT), or pure deflagration – WD progenitors, and WD progenitor metallicity, and analyse their detailed nucleosynthetic abundances and associated clumping. We find that pure deflagrations naturally give rise to clumpy distributions of neutronized species concentrated towards the outer limb of the remnant and confirm DDTs have smoothly structured ejecta with a central concentration of neutronization. Our findings indicate that 3C 397 was most likely a pure deflagration of a high central density WD. We discuss a range of implications of these findings for the broader SN Ia progenitor problem. [ABSTRACT FROM AUTHOR]

The present article aims to study the behavior of RC columns under blast loading. A nonlinear dynamic Three‐Dimensional (3D) Finite Element FE model‐based explicit solver available in ABAQUS Software is used. A parametric study is investigated to enhance the blast resistance of RC columns under three different scaled distances z of an explosion, that is, 0.23, 0.5, and 1.07 m/kg1/3 for close, intermediate, and Far in‐distance. In addition, three levels of concrete grades are used, which are Normal Strength Concrete (NSC), High Strength Concrete (HSC), and Ultra High‐Performance Concrete (UHPC). The study also considers Three reinforcement ratios for longitudinal and transverse reinforcement ratios of (ρL = 1.28%, 2.4%, and 3.1%) and (ρs = 0.6%, 0.9%, and 1.35%), respectively. Further, three different Axial Load Ratios, ALR = 0.01, 0.2, and 0.4, are considered to examine the effect of increasing ALR on the RC column under close explosion. For more investigation, the parametric analysis considers two geometrical shapes of RC columns (square and circular). The material behaviors of concrete and reinforcing steel bars are represented using Concrete Damage Plasticity (CDP) and Johnson–Cook (J–C) models, respectively, available in ABAQUS Software. The FE model has been initially validated against experimental study. The FE‐predicted deflection and damage were observed and agreed with the practical cases. In addition, the parametric study's results demonstrate that the RC column's blast deflection is significantly reduced with increasing reinforcement ratios. However, increasing concrete grade could efficiently reduce blast damage and deflection. Furthermore, compared with NSC, UHPC significantly reduced maximum damage and deflection by around 60% for square and 55% for circular columns, respectively. [ABSTRACT FROM AUTHOR]

Recently, studies on blast-proof panels, which were attached to structures to protect facilities from local damage caused by explosions, have been actively performed. However, blast-proof panels are impractical yet due to the high installation cost and difficulty in construction, and protection performance for explosions inside a structure is not evaluated. In this study, a blast-proof panel consisting of concrete material was devised to ensure economic feasibility and constructability. Then, the protection performance of the concrete blast-proof panel for internal explosions was analyzed by numerical simulations and field experiments. First, field experiments on concrete explosion-proof panels were conducted for two cases, where panels without and with energy-absorbing foam were installed. As a result, the concrete blast-proof panel reduced the displacement of structures by up to 22% and the acceleration of structures by up to 86%. However, the reliability of the field experiment data was insufficient due to the shear failure of the test structure during experiments. Therefore, additional analysis was conducted by developing a numerical model. A series of numerical simulations was conducted according to the various densities of the energy-absorbing foam that was inserted between the panel and structure. Consequently, the optimum density of the impact-absorbing material differed depending on the type of structure damage to reduce (i.e., the displacement or acceleration of the structure). Highlights: Concrete blast-proof panel was designed considering economic and constructability. Protection performance of panel was numerically and experimentally evaluated. The panel significantly reduced displacement and acceleration of structure against internal explosion. Density of energy-absorbing foam in panels should be designed based on protective target. [ABSTRACT FROM AUTHOR]

Aims. Recent observations of core-collapse supernovae (SNe) suggest aspherical explosions. Globally, aspherical structures in SN explosions are thought to encode information regarding the underlying explosion mechanism. However, the exact explosion geometries from the inner cores to the outer envelopes are poorly understood. Methods. Here, we present photometric, spectroscopic, and polarimetric observations of the Type IIP SN 2021yja and discuss its explosion geometry in comparison to those of other Type IIP SNe that show large-scale aspherical structures in their hydrogen envelopes (SNe 2012aw, 2013ej and 2017gmr). Results. During the plateau phase, SNe 2012aw and 2021yja exhibit high continuum polarization characterized by two components with perpendicular polarization angles. This behavior can be interpreted as being due to a bipolar explosion, where the SN ejecta is composed of a polar (energetic) component and an equatorial (bulk) component. In such a bipolar explosion, an aspherical axis created by the polar ejecta would dominate at early phases, while the perpendicular axis along the equatorial ejecta would emerge at late phases after the photosphere in the polar ejecta has receded. Our interpretation of the explosions in SNe 2012aw and 2021yja as bipolar is also supported by other observational properties, including the time evolution of the line velocities and the line shapes in the nebular spectra. The polarization of other Type IIP SNe that show large-scale aspherical structures in the hydrogen envelope (SNe 2013ej and 2017gmr) is also consistent with the bipolar-explosion scenario, although this is not conclusive. [ABSTRACT FROM AUTHOR]

Copyright of Elektronik Industrie is the property of Hüthig GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thermal response and chemical reaction of AP/HTPB in flame area of fire are different with that in near flame area of fire. AP/HTPB in flame area of fire is uniformly heated. This process is similar to that in the slow cook-off experiment. Thermal response and chemical reaction in AP/HTPB in near flame area of fire are not uniform, which cannot be characterized by slow cook-off experiment. In this study, a pool fire cook-off model has been established to examine hazard and critical condition of AP/HTPB explosion induced in near flame area of fire. The effects of fire temperatures on the AP/HTPB propellant explosion induced in near flame area of fire are studied using numerical simulation. Critical fire temperature (lowest fire temperature) for inducing explosion of AP/HTPB is 673K at that the initial explosion temperature of 576.4K at which explosion is initiated. At the fire temperature of lower than critical fire temperature, the AP/HTPB explosion cannot be initiated in the near flame area of fire. The ignition delay increases linearly with the decrease of fire temperature. At 673K fire temperature, the ignition delay is 1600s. The initial explosion temperature in the AP/HTPB propellant in the near flame area of fire increases from 736.5K to 790K with the decrease of fire temperature in range from 2000K to 1600K. However, initial explosion temperature of the AP/HTPB decreases from 790K to 576.4K with the decrease of fire temperature in range from 1600K to 673K. The initial explosion temperature in the AP/HTPB propellant in near flame area of fire reaches the maximum value of 790K at 1600K fire temperature. [ABSTRACT FROM AUTHOR]

We here focus on the behavior of supernovae that technically explode in 1D (spherical symmetry). When simulated in 3D, however, the outcomes of representative progenitors of this class are quite different in almost all relevant quantities. In 3D, the explosion energies can be 2 to 10 times higher, and there are correspondingly large differences in the 56Ni yields. These differences between the 3D and 1D simulations reflect in part the relative delay to explosion of the latter and in the former the presence of protoneutron star convection that boosts the driving neutrino luminosities by as much as ∼50% at later times. In addition, we find that the ejecta in 3D models are more neutron-rich, resulting in significant weak r -process and 48Ca yields. Furthermore, we find that in 3D the core is an interesting, though subdominant, source of acoustic power. In summary, we find that though a model might be found theoretically to explode in 1D, one must perform supernova simulations in 3D to capture most of the associated observables. The differences between 1D and 3D models are just too large to ignore. [ABSTRACT FROM AUTHOR]

Programmable self-assembly has seen an explosion in the diversity of synthetic crystalline materials, but developing strategies that target "self-limiting" assemblies has remained a challenge. Among these, self-closing structures, in which the local curvature defines the finite global size, are prone to polymorphism due to thermal bending fluctuations, a problem that worsens with increasing target size. Here, we show that assembly complexity can be used to eliminate this source of polymorphism in the assembly of tubules. Using many distinct components, we prune the local density of off-target geometries, increasing the selectivity of the tubule width and helicity to nearly 100%. We further show that by reducing the design constraints to target either the pitch or the width alone, fewer components are needed to reach complete selectivity. Combining experiments with theory, we reveal an economical limit, which determines the minimum number of components required to create arbitrary assembly sizes with full selectivity. [ABSTRACT FROM AUTHOR]

This study presents an experimental investigation on explosion flame venting from an explosion tube (the part with premixed gas) to a relief tube (the part without premixed gas), focusing on the vented flame behavior in the relief tube. Four bifurcated angles (θ), corresponding to 0°, 30°, 45°, and 60°, were used to evaluate the effect of bifurcated angles on vented flame behaviors and pressure dynamics in relief tubes. Experiments were carried out at ambient temperature and pressure, and the stoichiometric syngas/air mixtures with various hydrogen volume fractions were tested. Results showed that the explosion in the relief tube was a secondary explosion caused by unburned syngas/air mixtures venting from the premixed tube. When the flame vented from the explosion tube to the premixed tube, the flame transformed from laminar to turbulent, resulting in faster flame propagation speed and stronger explosion pressure than the premixed explosion. The increment in hydrogen volume fraction increases the fuel's reactivity, resulting in a stronger secondary explosion. For a given hydrogen fraction, the maximum secondary explosion overpressure initially decreases, then increases with varying bifurcated angles, reaching a minimum at θ = 30°. The shunt extent of the flame and pressure wave is determined by the bifurcated angles, which determine the intensity of the flame's turbulization and finally affect the secondary explosion in the bifurcated relief tube. [Display omitted] • The effect of bifurcated angles on a bounded directional venting explosion is studied. • There is a secondary explosion in the relief tube caused by the explosion venting. • The mechanism of the secondary explosion in the relief tubes is discussed. • The secondary explosion has a faster flame propagation speed and higher explosion pressure. • The minimum value of maximum secondary explosion pressure was attained at 30°. [ABSTRACT FROM AUTHOR]

This study investigates the relationship between car drivers' approaches to hydrogen refilling and the associated risks. The focus is on a dispenser operated directly by drivers. The awareness of the consequences of careless operations on hydrogen installations differs among drivers. In this study, models of cautious and careless drivers were considered to analyse how their approach affects the risk of the refuelling process. This research involves the development of scenarios for hazardous events and their consequences, such as fires or explosions. The probabilities calculated for the scenarios, together with the death probabilities for the consequences, allowed us to determine the risks and compare the results for a cautious and careless driver. The highest values of the risk obtained in the research for cautious and careless drivers were 7.68⋅10−5 and 3.22⋅10−4. [Display omitted] • A hydrogen refuelling station is a structure of objects that may cause failures. • The analysis includes assessment of experts and fuzzy logic. • Consequences such as a fire or an explosion are investigated. • The calculated risk determines a hazard area around the analysed object. • The driver's experience is an important factor determining the safety of refuelling. [ABSTRACT FROM AUTHOR]

Pine wilt disease is one of the most serious forest diseases that kills pine trees. Most of the nematode-infected pines are fumigated or locally incinerated and are thus not appropriately utilized. This study explored methods to utilize abandoned nematode-infected pines. The chemical compositions of healthy and nematode-infected pines were analyzed, and the neuroprotective effects of phenolic compounds extracted after steam explosion treatment were investigated. In terms of chemical composition, the nematode-infected pine chips suffered more damage from the steam explosion treatment than the healthy pine chips. In addition, the total phenolic compound content showed a clear difference depending on the presence of infection and steam explosion conditions. The maximum total phenolic compound content of extracted ethanol was found when the nematode-infected pine chip was subjected to steam explosion with a severity factor (Ro) of 3.82. The steam exploded pine extract of 10 µg/mL inhibited glutamate-induced early apoptotic cell death compared to cells treated with 10 mM glutamate alone. These results suggested that steamexploded pine can be used as an effective natural material for neuronal cell protection. [ABSTRACT FROM AUTHOR]

This research was aimed at comparing the fire characteristics of different types of pepper in the context of explosion prevention. The following characteristics were studied: explosion pressure Pmax and Kst at selected concentrations, ignition temperature of the deposited dust layer from the hot surface, and minimum ignition energy. The comparison of the chemical properties of the used types of pepper was performed using TG/DSC. The results of the measurements suggest that different types of peppers exhibit different explosion characteristics. Each sample reached the maximum value of the explosion pressure and rate of pressure rise at different concentrations. The volume of the explosion chamber used also influenced the explosion characteristics. It is a consequence of the fact that the explosion characteristics strongly depend on the mechanism of action of a particular igniter. The minimum effect on the safety characteristics was observed when measuring the minimum ignition energy and the minimum ignition temperature of the dust layer from the hot surface. The results of the measurements suggest that different types of peppers exhibit different explosion characteristics. This information should then be considered in explosion prevention. [ABSTRACT FROM AUTHOR]

Proactive prevention and fighting fire at industrial facilities, often located in urbanized clusters, should include the use of modern methods for modeling danger zones that appear during the spread of the harmful combustion products of various chemicals. Simulation modeling is a method that allows predicting the parameters of a danger zone, taking into account a number of technological, landscape, and natural-climatic factors that have a certain variability. The purpose of this research is to develop a mathematical simulation model of the formation process of a danger zone during an emergency at an industrial facility, including an explosion of a container with chemicals and fire, with the spread of an aerosol and smoke cloud near residential areas. The subject of this study was the development of a simulation model of a danger zone of combustion gases and its graphical interpretation as a starting point for timely decision making on evacuation by an official. The mathematical model of the process of danger zone formation during an explosion and fire at an industrial facility presented in this article is based on the creation of a GSL library from data on the mass of explosion and combustion products, verification using the Wald test, and the use of algorithms for calculating the starting and ending points of the danger zone for various factor values' variables, constructing ellipses of the boundaries of the distribution of pollution spots. The developed model makes it possible to calculate the linear dimensions and area of the danger zone under optimistic and pessimistic scenarios, constructing a graphical diagram of the zones of toxic doses from the source of explosion and combustion. The results obtained from the modeling can serve as the basis for making quick decisions about evacuating residents from nearby areas. [ABSTRACT FROM AUTHOR]

In actual combat, the attack of the warhead on the target is a dynamic process, and there is a significant difference in shock wave pressure between dynamic and static explosions of ammunition, while dynamic explosions are more in line with actual combat situations. Therefore, conducting research on the distribution law of dynamic explosion shock wave pressure in ammunition has more practical value for evaluating the damage power of ammunition and guiding its use. This study used the display explosion dynamics simulation software AUTODYN to conduct simulation analysis on the pressure distribution patterns of static and dynamic explosion shock waves, clarifying the differences in pressure distribution between dynamic and static explosions. Considering the factors that affect the distribution law of dynamic explosion shock wave pressure, a BP neural network based correlation prediction model for static and dynamic explosion shock wave pressure was constructed, and the prediction accuracy of the model was verified. The analysis results indicate that the pressure distribution of dynamic explosion shock waves has a significant velocity tendency; The prediction accuracy of the static and dynamic shock wave pressure correlation prediction model based on BP neural network is better than 90.7%. The research results have improved the accuracy of the calculation of dynamic explosion shock wave pressure in warheads, providing effective calculation methods and scientific data support for the calculation of dynamic explosion shock wave pressure and the evaluation of damage power. [ABSTRACT FROM AUTHOR]

Tactical vehicles operating in conflict regions have a risk of threats both within and outside combat zones. Enhancing protection against external threats is important, necessitating compliance with standards of ballistic resistance. These standards classify and test the bullet-resistant capabilities of military vehicles, construction materials, and personal protective gear. Occupant protection seats have been fabricated with impact and vibration absorption systems of pantograph with spring structure to reduce the impact on occupants. The experimental results demonstrate that the designed occupant protection seats effectively absorb the impact caused by an underbody explosion. Data obtained from accelerometers installed throughout the test facility indicate a significant reduction in impact velocity as it is absorbed by the pantograph with spring structure. This reduction assumes an 80 % decrease in impact transferred to anthropomorphic test devices occupants. These results imply that the designed occupant protection seats safely protect occupants within tactical vehicles. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study of the explosion parameters of ethanol–air mixture at high pressure and temperature is essential for the safe production of ethanol. However, the explosion characteristics of ethanol vapor at various pressures and temperatures are limited. The mechanism at the flammability limits of ethanol has not been clarified, and the corresponding prediction model is also lacking. In this study, chemical kinetics and machine learning are used to study the mechanism of ethanol explosion and build predictive models, respectively. Our findings show that an increase in the initial pressure has a more pronounced influence on the explosion pressure (Pex) and pressure rise rate (dp/dt) than an increase of temperature. The variation trend of the upper flammability limit (UFL) of ethanol is related to the different effects of temperature and pressure on OH radicals. H + O2<>OH + O and HO2 + CH3<>OH + CH3O had the greatest effect on the generation of OH radicals. The quantitative relationship between the H, O, and OH radicals and UFL was constructed by machine learning, providing a new research perspective for the prediction of the UFL of an inflammable fuel under different pressures and temperatures. The results of the study will provide theoretical and practical guidance for the prevention and control of explosions in the ethanol production process. [ABSTRACT FROM AUTHOR]

This review gathered and discussed the available results on the thermal hazards, thermal kinetics, decomposition mechanism, autocatalytic behavior, thermal explosion, deflagration ability, and incompatibility hazards associated with the thermal decomposition of methyl ethyl ketone peroxide (MEKPO). The present review constructed a diagram showing all activation energy Ea and log A values for the thermal decomposition of MEKPO. Some disagreement exists in the values of Ea and log A (unit: s−1 M1−n) derived from differential scanning calorimetry; thus, more extensive studies must be conducted to resolve disputes. Nearly no literature exists on the thermal explosion and deflagration ability of MEKPO, and the reactions of MEKPO with incompatible contaminants remain unclear. Concerning the complex decomposition mechanism of MEKPO, experimental determination and identifications of intermediates have not been obtained. Available technology must be improved to enable the collection of accurate data on thermal hazards, thermal kinetics, decomposition mechanisms, explosion and deflagration phenomena, autocatalytic behavior, and incompatibility. This review has integrated an up‐to‐date summary of the most recent approaches and offers perspectives regarding future research. These current findings can serve as a reference for completing subsequent experimental investigations, theoretical studies, and designs of inherently safer measures for producing or handling MEKPO. [ABSTRACT FROM AUTHOR]

In order to reduce the power of methane explosion in natural gas pipelines and effectively improve the explosion suppression efficiency of a single explosion suppressant, we carry out the explosion suppression of HFC‐227ea/carbon dioxide mixed gas as well as mixed gas/ultrafine water mist through a self‐built methane explosion suppression experimental platform. Based on the changes in parameters such as explosion overpressure, flame propagation velocity, and flame propagation structure, the coupling mechanism of methane explosion suppression between mixed gases and between mixed gases and ultrafine water mist is revealed, which provides scientific support for promoting the development of methane explosion suppression technology. The experimental results show that when the mixed gas HFC‐227ea/carbon dioxide and ultrafine water mist synergistically suppresses methane explosion, the addition of the mixed gas can effectively improve the suppression effect of ultrafine water mist on methane explosion. [ABSTRACT FROM AUTHOR]

The biochemical pathway for propionic acid (PA) production is an interesting alternative that can include the utilization of biomass as feedstock. This study evaluated the utilization of Agave bagasse (AB), a lignocellulosic residue, to produce PA by Propionibacterium acidipropinici in batch systems (125 mL‐hermetic bottles and 1000 mL‐bioreactor). The process included a steam explosion pretreatment at 142°C for 15 min and enzymatic hydrolysis, where solid loading (2.75% and 5% in pretreatment and 2.5%, 3.75%, and 5% in enzymatic hydrolysis) was evaluated. Furthermore, the enzymatic concentrations of 18.3 filter paper unit (FPU)/gAB (1×) of Cellic® CTec2 and 1.5× and 3× were tested. The yields of total carbohydrates (TC) obtained at the two solid loadings tested in the pretreatment were statistically similar, but the 3x enzymatic concentration enhanced the yields of TC, glucose, and xylose (0.23 ± 0.01, 0.15 ± 0.01 and 0.03 ± 0.01 g/gAB, respectively). The hydrolysates obtained under these conditions were evaluated as carbon sources for PA production, obtaining a productivity of 0.069 ± 0.006 g/L h and a yield product/substrate of 0.44 gPA/gTC. The control of pH in the culture reduced the fermentation time in the bioreactor by 52% compared with the hermetic bottles without pH control. The potential of hydrolysates as carbon sources for PA production was evidenced, as approximately 50% of the initial carbon was converted to this product. The observed yield product/substrate was similar to those reported from hydrolysates of diverse biomass types, pretreatments, or enzymatic cocktails and the same or related microorganisms. However, the system studied has advantages, such as not requiring the addition of chemical or detoxification stage, and lower temperature and time compared to other pretreatments. [ABSTRACT FROM AUTHOR]

Copyright of Die Unfallchirurgie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Die Unfallchirurgie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The chemical industry oversees the transformation of raw materials into products through unit operations that require appropriate organization to avoid accidents. Hence, it is important to do analyses to identify any possible mistakes, substances involved, or common sources of accidents in the industry to avoid such errors and design better safety measures to create a safer space for the chemical industry, which is hugely important and boasts a worldwide presence. This document presents an analysis of chemical industry‐related accidents in Saudi Arabia, namely fires, explosions, and toxic clouds which occurred in the chemical and petrochemical industries and while transporting hazardous materials in the last 46 years. Three databases—one for each type of accident—were created with information collected from articles, newspapers, videos, and papers. 'Explosion', 'fire', and 'toxic clouds' were the key words used for the research, focusing on accident taking place in Saudi Arabia. Once the information had been collected, the accidents were filtered, checked, and moved to a fourth general database. It is shown that 54.0% of all related accidents were fires, 25.4% toxic clouds, and 20.6% were explosions. The provinces with the most registered accidents were Riyadh (15), Jeddah (10), and Jubail (6). [ABSTRACT FROM AUTHOR]

Process lifecycle has several stages, including process design covered in multiple stages. Process economics is a vital factor in finalizing the process design. Besides economics, inherent safety is an important concept contributing to sustainable process design generation. The inherent safety concept has been applied via equipment characteristics for individual equipment. Since a method considering inherent safety with equipment aspects and process economics has not been available, therefore, a new method has been proposed, namely sustainable process design for heat exchanger network (SPDHEN), to integrate inherent safety, equipment aspects, and process economics. SPDHEN uses indexing to identify the critical heat exchanger, which is then examined via hazard analysis for an explosion. For unacceptable hazards, inherent safety principles are engaged to generate design alternatives for which process economics is examined too. The final design would be inherently safer with the best profit margin. The proposed method has been studied for the ammonia synthesis loop. It is concluded that the explosion hazard has been reduced to a tolerable level by using inherent guide words with a marginal compromise on quantity of ammonia produced, that is, 0.32%. This method is straightforward and can be useful for process engineers to generate sustainable process designs for heat exchanger networks considering safety and process economics simultaneously. [ABSTRACT FROM AUTHOR]

Underwater electric wire explosion (UEWE) has great potential as a shockwave source for medical and industrial applications. This paper focuses on the process of the sub-millisecond underwater electrical wire explosion (smUEWE). The study compared the smUEWE and the microsecond underwater electrical wire explosion, which revealed the occurrence of partial vaporization under smUEWE, leading to the formation of bamboo-shaped cavities and frontal shock waves. The experiments of smUEWE were carried out under different stored energy, the results indicated the plasma shrinkage and cavity separation during the overall ionization process. Additionally, the study observed secondary breakdown caused by the uneven distribution of ionization products. An analysis was conducted on smUEWE considering partial vaporization, which divided the electrical explosion into a positive feedback process which promoted the axial instability and a negative feedback process which formed the uniform plasma channel. The analysis results was consistent with the experimental results. [ABSTRACT FROM AUTHOR]