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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]

Shock waves in geological materials are characterized by a sudden release of rapidly expanding gas, liquid, and solid particles. These shock waves may occur due to explosive volcanic eruptions or be artificially triggered. In fact, underground explosions have often been used as an engineering solution for large‐scale excavation, stimulating oil and gas recovery, creating cavities for underground waste storage, and even extinguishing gas field fires. As such, hydrocodes capable of simulating the rapid and significant deformation under extreme conditions can be a valuable tool for ensuring the safety of the explosions. Nevertheless, as most of the hydrocodes are often formulated in an Eulerian grid, this setting makes it non‐trivial to track the deformation configuration of the materials without a level set. The objective of this paper is to propose the use of the material point method equipped with appropriate equation of state (EOS) models as a hydrocode suitable to simulate underground explosions of transverse isotropic geomaterials. To capture the anisotropic effect of the common layered soil deposits, we introduce a new MPM hydrocode where an anisotropic version of the Mie‐Gruneisen EOS is coupled with a frictional Drucker‐Prager plasticity model to replicate the high‐strain‐rate constitutive responses of soil. By leveraging the Lagrangian nature of material points to capture the historical dependence and the Eulerian calculation of internal force, the resultant model is capable of simulating the rapid evolution of geometry of the soil as well as the high‐strain‐rate soil mechanics of anisotropic materials. [ABSTRACT FROM AUTHOR]

In the present study, the dynamic response and damage of concrete-filled steel tubular (CFST) columns under close-in explosion were numerically studied. An extensive parametric study was carried out to investigate the effects of column height, diameter, wall thickness, yield strength of steel, compressive strength of concrete, and axial load ratio on the residual midheight displacement (RMHD) and residual axial load-bearing capacity (RALBC). It was found that the RALBC is strongly correlated with the RMHD under different explosion scenarios. Three models were developed using Extreme Gradient Boosting (XGBoost) based on a database comprising 1,708 circular CFST column samples. These models aimed to predict the relationship between RMHD and RALBC, utilizing different combinations of input variables. Accurate prediction results can be obtained from all the models, and the selection of a model can be based on the availability of known input variables. The third prediction model, which does not require knowledge of the blast loading parameters and axial load ratio, which are usually difficult to obtain, can yield accurate results. Therefore, it can be used to quickly evaluate the RALBC of CFST columns. Finally, the prediction model was further interpreted locally and globally using the additive feature attribution method Shapley Additive Explanation (SHAP). Through the SHAP interpretation, the contribution of each input variable to the RALBC of CFST columns was analyzed. This provided valuable insights into the impact of individual variables on the prediction results. [ABSTRACT FROM AUTHOR]

Underground mine structures like mine seals or built-in-place (BIP) refuge alternatives (RA) are exposed to specific loadings like explosions because of overlying and underlying strata conditions. Previous studies worked on the vertical loading response of structures like abutments from panel extraction but not the explosion resistance upon being subjected to these vertical strata loads. In this study, two steel-reinforced concrete wall designs as seal and RA applications are simulated to examine the performance and failure analysis under abutment-loading conditions during an explosion for a coal mine model using dynamic analysis by a distinct element code (3DEC). The available abutment monitoring data by longwall stoppings was used to estimate the abutment-loading conditions. The model setup was calibrated through two validation stages: (1) the concrete wall simulation with the explosion test of steel-reinforced concrete mine seal conducted by previous researchers; and (2) the stress change at the strata by the tailgate convergence-abutment-load multiplier curve. The calibrated models are subjected to various dynamic loadings to simulate explosions. The findings demonstrate that, in addition to magnitude, the pressure versus time mode of loading significantly influences the wall response. Instantaneous loading criteria can provide more cautious measurements to assess how well such walls operate in similar situations. Except for a few cases, the deformations after a single explosion are more pronounced for the effects of subsequent second and third explosions. As a result, the changes in deformation during subsequent explosions are relatively minor compared with the initial permanent deflections. [ABSTRACT FROM AUTHOR]

The effects of the vent burst pressure (P v) on the vented explosion of hydrogen-methane-air mixtures are investigated in a cylindrical vessel connected with a duct. The results demonstrate that P v significantly affects the flame behaviors and overpressure inside and outside the venting configuration. The flame front velocity at the vent increases with P v. Two pressure peaks, P a c , caused by the acoustically enhanced combustion, and P s e , caused by the secondary explosion, dominate within the vessel at P v ＜ 132 kPa and P v ≥ 132 kPa, respectively. The maximum overpressure (P max) inside the duct increases with P v. The maximum pressure rise (d P / d t) of the duct is always higher than that of the vessel. As P v increases, increased turbulence of unburned gases within the duct results in higher d P / d t. Exit flame speed increases with P v. When P v ≥ 153 kPa, "Mach disk" appears outside the relief duct. Three pressure peaks, P a , P b , and P e x t , due to vent failure, the secondary explosion, and the external explosion, respectively, occur in the external pressure curve. P b dominates outside the configuration except for P v = 153 kPa. • Initial flame velocity in the duct increased with P v. • P v was positively correlated with P max inside the duct. • "Mach disk" appeared only when P v ≥ 153 kPa. • Both P a and P e x t increased with the increase of P v. [ABSTRACT FROM AUTHOR]

The peak explosion pressure and maximum rate of pressure rise of explosions in confined spaces are key safety parameters to evaluate the hazard of processes running in closed vessels and to design enclosures able to withstand explosions or of their vents used as relief devices. These properties are examined in the present paper, for hydrogen-hydrocarbon-air mixtures at sub-atmospheric pressures, using propane and n -butane as test fuels and variable hydrogen ratios between 0 and 0.3. The experimental study was carried out in a sphere and a cylindrical chamber at room temperature and sub-atmospheric pressures (between 0.3 and 1.0 bar). On the basis of pressure recordings, the characteristic explosion indices, i.e., the maximum explosion pressure (p max), maximum rate of pressure rise ((dp/dt) max), deflagration index (K G), and time to peak pressure (θ max) were derived. Numerical simulations were used to determine the adiabatic explosion pressures and adiabatic flame temperatures of isochoric combustion. The effects of initial pressure (p 0), hydrogen concentration, and shape and size of the explosion vessel on explosion indices are discussed. For each hydrogen concentration of the blended fuels, linear correlations p max = f(p 0) and (dp/dt) max = f(p 0) were found. In addition, the heat loss to the walls during explosion propagation was estimated on the basis of the difference between the adiabatic and experimental explosion pressures. The amount of heat lost increases with the increase of hydrogen blending ratio and vessel asymmetry. • Hydrogen-blended propane-air and butane-air explosions were studied in two closed vessels. • The experiments were performed at various initial pressures between 0.3 and 1.0 bar. • As Hydrogen blending ratio increases, the explosion pressure, the maximum rate of pressure rise, and the severity factor increase. • The increase of hydrogen blending ratio results in the decrease of the explosion times. • The observed variations depend largely on the volume and shape of the explosion vessel. [ABSTRACT FROM AUTHOR]

Hydrogen is a carbon-free energy source that can be obtained from various sources. The blending of hydrogen represents a transitional phase in the shift from natural gas systems to hydrogen-based systems. However, concerns about the safety implications of introducing hydrogen have led to extensive discussions. This paper utilizes Fluent 17.0 numerical simulation software to simulate the leakage of hydrogen-blended natural gas in a closed domestic kitchen and analyze the concentration distribution and its variation pattern after a leakage. An experimental platform is set up, and a mixture of nitrogen and helium gas is used as a substitute for hydrogen-blended natural gas for the simulations and experiments. The simulation results demonstrate that the leaked gas spreads and accumulates towards the top of the space, gradually filling the entire area as the leak persists. As the hydrogen content in the leaked gas increases, the dispersion capacity of the gas in the confined space also increases. Furthermore, as the flow rate of the leaked gas increases, the average concentration of the leaked gas rises, and the gas stratification in the confined kitchen diminishes. The concentration distribution observed in the experiments aligns with the simulation results. After establishing the feasibility conditions of the model, the dispersion of the hydrogen-blended natural gas in the kitchen is further simulated. The results suggest that blending hydrogen into the gas enhances the dispersion of the gas after a leak, leading to a wider distribution within the kitchen and an increased risk in the event of a leak. Additionally, this paper employs the CASD module of FLACS 11.0 software to construct a three-dimensional geometric model of the domestic kitchen for simulation studies on the explosion of hydrogen-blended natural gas in a confined space. By adjusting the hydrogen ratio in the combustible gases present in the space and examining the variations in hydrogen concentration and external conditions, such as opening or closing the door, the influence on parameters including the peak explosion pressure, explosion overpressure, explosion flame temperature, and explosion response time are examined. Furthermore, the extent of the explosion area is determined, and the effect of hydrogen on the blast is clarified. [ABSTRACT FROM AUTHOR]

Hydrogen, as a promising energy vector, can cause an explosion or even a detonation due to its unique physical and chemical properties. Water spray is an ideal mitigant for detonations, because of its multiple benefits. The one-dimensional Zel'dovich–von Neumann–Döring (ZND) structure and multi-dimensional detonation cellular structure are introduced. Effectiveness of explosion inhibition by water sprays is linked with the droplet characteristics (diameter, concentration, spray or cloud size) and shock intensity (pressure or Mach No). The mitigation effect can be characterized by the momentum or heat transfer by quasi-steady drag. Moreover, gas-droplet two-phase detonation structures are clarified. Analyses of the mean structures show that mass, momentum, and energy transfer alter the hydrodynamic thickness. Droplet breakup and evaporation occur behind the leading shock. The peak pressure trajectories of the detonation wave are influenced by the gas equivalence ratio, water droplet concentration, and droplet size. Parametric studies on the water spray detonation further provide a guidance for the detonation inhibition. Finally, transferring mass, heat, and momentum between phases can mitigate explosions and detonations, reducing flame reaction rates and shock intensity. • Parametric studies on mitigating explosions and detonations are discussed. • Detonation front structures of gas-droplet mixtures are initially clarified. • Peak pressure trajectories of the unsteady detonations are analyzed. • Hydrogen hazard mitigation mechanisms are first summarized. • Indications of research gaps for future investigations are presented. [ABSTRACT FROM AUTHOR]

Accurate prediction of blast loading from accidental hydrogen-air cloud explosion is critical for the planning, design, and operation of the hydrogen industry. This study proposes an efficient and accurate prediction model of explosion loads from hydrogen-air cloud explosions in vented silos. Based on the Bayesian regularization and data augmentation, an artificial neural network (ANN) model is generated and trained with the data collected from computational fluid dynamics (CFD) simulations using FLACS. The influences of various parameters including the silo dimensions (diameter and height), the ventilation size (width and length), and the ventilation panel activation pressures are considered. Analysis shows that the R2 value of the ANN model predictions and CFD simulation results exceeds 0.99. The developed ANN model could provide almost instantaneous prediction of the peak overpressure, the rise rate of overpressure, and the impulse for constructing the blast loading time history, which can be used in the design analysis and safety assessment of structures exposed to hydrogen explosions. Additionally, the model interpretability was conducted to analyse the importance and contribution of the input variables, which also verifies the reliability of the prediction model. • A comprehensive ANN model with interpretability was developed to predict Hydrogen-Air explosion loads. • Over 400 data sets for ANN training are generated via CFD simulation using FLACS Hydrogen Modular. • The performance of the developed ANN model closely aligns with CFD simulation results. • The developed model combines the advantages of simulations, empirical methods, and neural networks. [ABSTRACT FROM AUTHOR]

Volcanic hazards associated with lava flows advancing on snow cover are often underrated, although sudden explosions related to different processes of lava-snow/ice contact can occur rapidly and are only preceded by small, easily underrated precursors. On 16 March 2017, during a mildly effusive and explosive eruption at Mount Etna, Italy, a slowly advancing lava lobe interacted with the snow cover to produce a sudden, brief sequence of explosions. White vapor, brown ash, and coarse material were suddenly ejected, and the products struck a group of people, injuring some of them. The proximal deposit formed a continuous mantle of ash, lapilli, and decimeter-sized bombs, while the ballistic material travelled up to 200 m from the lava edge. The deposit was estimated to have a mass of 7.1 ± 0.8 x 104 kg, which corresponds to a volume of 32.0 ± 3.6 m³ of lava being removed by the explosion. Data related to the texture and morphology of the ejected clasts were used to constrain a model of lava-snow interaction. The results suggest that the mechanism causing the explosions was the progressive build-up of pressure due to vapor accumulation under the lava flow, while no evidence was found for the occurrence of fuel-coolant interaction processes. Although these low-intensity explosions are not particularly frequent, the data set collected provides, for the first time, quantitative information about the processes involved and the associated hazard and suggests that mitigation measures should be established to prevent potentially dramatic accidents at worldwide volcanoes frequented by tourists and with fairly easy access, such as Etna. [ABSTRACT FROM AUTHOR]

Power outages can cause harm to both society and individual health. Among the crucial elements of power systems, power transformers play a vital role, and their failures can lead to incidents and disruptions. According to statistics, almost 50% of the explosions and fires in the power transformer are caused by oil‐impregnated paper (OIP) bushing failures. Moreover, moisture is a crucial factor that affects the health of OIP bushings, and assessing the moisture level in OIP bushings is vital to guarantee the safety of power systems. While the frequency‐domain dielectric spectroscopy (FDS) method has been widely used to assess the moisture content of OIP bushings on‐site, it has the disadvantage of requiring a long measurement time. Therefore, a novel technique was proposed in this study that involves measuring the OIP bushing dissipation factor (tanδ) at 1 Hz to estimate the moisture content in a significantly shorter time. Five samples of OIP with various moisture levels have been selected, and an equation based on the OIPs' value of tanδ at 1 Hz was proposed to assess the moisture level of OIP bushings. Furthermore, the validity of the proposed method was successfully verified, proving its precision and time efficiency. [ABSTRACT FROM AUTHOR]

Purpose: Determine the prevalence of otological symptoms and tympanic membrane perforation, healing rates of tympanic membrane perforation with surgical and conservative management, and hearing function in civilian victims of terrorist explosions. Methods: A systematic review was conducted with searches on Medline, Embase, EMCare and CINAHL for publications between the 1st January 1945 and 26th May 2023. Studies with quantitative data addressing our aims were included. This review is registered with PROSPERO: CRD42020166768. Among 2611 studies screened, 18 studies comprising prospective and retrospective cohort studies were included. Results: The percentage of eardrums perforated in patients admitted to hospital, under ENT follow up and attending the emergency department is 69.0% (CI 55.5–80.5%), 38.7% (CI 19.0–63.0%, I2 0.715%) and 21.0% (CI 11.9–34.3%, I2 0.718%) respectively. Perforated eardrums heal spontaneously in 62.9% (CI 50.4–73.8%, I2 0.687%) of cases and in 88.8% (CI 75.9–96.3%, I2 0.500%) of cases after surgery. Common symptoms present within one month of bombings are tinnitus 84.7% (CI 70.0–92.9%, I2 0.506%), hearing loss 83.0% (CI 64.5–92.9%, I2 0.505%) and ear fullness 59.7% (CI 13.4–93.4%, I2 0.719). Symptomatic status between one and six months commonly include no symptoms 57.5% (CI 46.0–68.3%), hearing loss 35.4% (CI 21.8–51.8%, I2 0.673%) and tinnitus 15.6% (CI 4.9–40.0%, I2 0.500%). Within one month of bombings, the most common hearing abnormality is sensorineural hearing loss affecting 26.9% (CI 16.9–40.1%, I2 0.689%) of ears 43.5% (CI 33.4–54.2%, I2 0.500) of people. Conclusion: Tympanic membrane perforation, subjective hearing loss, tinnitus, ear fullness and sensorineural hearing loss are common sequelae of civilian terrorist explosions. [ABSTRACT FROM AUTHOR]

In this article, the M-estimator of the moderate deviations from a unit root model with possibly infinite variance errors is proposed. When the autoregressive coefficients are located on both sides of stationary and explosion, the asymptotic normal properties of the corresponding estimators for unknown parameters are proved, respectively. The asymptotic properties of the M-estimators are obtained in both the mildly integrated case and the mildly explosive case. [ABSTRACT FROM AUTHOR]

A theoretical method was optimized based on a wrinkled flame model for predicting the explosion pressure in confined chambers for typical low-carbon fuels, e.g., hydrogen (H 2), methane (CH 4), and ammonia/dimethyl ether/hydrogen (NH 3 /DME/H 2) blends, etc. It was found that the previous model with a wrinkling factor of Ξ Δ = e t (t is time) is only applicable to the explosions of H 2 fuel, while considerably underestimating the explosion pressures of other fuels such as CH 4 and NH 3 /DME/H 2 blends. For H 2 fuel where the pressure power exponent β > 0, the effect of flame wrinkling on the laminar burning velocity S L is less significant compared to that of adiabatic compression, so that an underestimated wrinkling factor does not affect the overall prediction of pressure by the model. However, for most fuels with β < 0, a more accurate representation of the wrinkling effect is necessary for pressure prediction. The results show that the model can be optimized by increasing the wrinkling factor to Ξ Δ = e 20 t that satisfactorily represents the effect of flame instabilities. The wrinkling factor remains constant (Ξ Δ = 2.46) after it reaches its maximum value of 2.46. Comparison of the model predictions to experiments shows that the optimized model can well predict the explosion pressures of various low-carbon fuels that experienced flame instability. • The wrinkled flame model for predicting the explosion pressure in confined chambers was optimized. • For H 2 , the effect of flame wrinkling on flame speed is less significant compared to that of adiabatic compression. • For fuels with β < 0, the wrinkling factor was increased to Ξ Δ = e 20 t with the maximum value of 2.46. • The optimized model can well predict the explosion pressures of different fuels at various initial conditions. [ABSTRACT FROM AUTHOR]

In this study, a shear-stiffening composite porous material (PU@CS) was developed using the dipping-drying technique, with polyurethane (PU) as the substrate. PU@CS not only overcomes the cold flow drawbacks of shear-stiffening gel (SSG) but also significantly enhances the mechanical properties of PU (with a one-order-of-magnitude increase in maximum storage modulus). The introduction of multi-walled carbon nanotubes (MWCNTs) overcomes the electrostatic aggregation drawback of PU. Due to its outstanding shear hardening effect, PU@CS exhibits superior explosion-proof compared to PU, and when filled to a length of 50 cm, it achieves complete quenching of hydrogen gas explosion flames, with a maximum explosion overpressure attenuation ratio of 87.2%. This work provides data support for the application of SSG in the field of explosion protection. [Display omitted] • Shear stiffening gel was applied in the explosion-proof for the first time. • The shear-stiffening composite explosion-proof material was prepared. • PU@CS has excellent antistatic properties and its explosion-proof mechanism is revealed. [ABSTRACT FROM AUTHOR]

To investigate the suppression effect of fluorine-containing explosion suppressants (FESs) on methane (CH4) explosions and the corresponding suppression mechanism, a 20-L spherical explosion testing device was used to analyze and compare the effects of perfluorohexanone (C6F12O) and heptafluoropropane (C3F7H) on CH4 explosion parameters. The explosion limit and pressure were obtained before and after adding these FESs. CH4 explosion triangles under the action of the FESs were drawn, and the explosion hazard degree (F) was determined. The results reveal that the addition of C6F12O and C3F7H reduces the upper explosion limit (UEL) and lower explosion limit (LEL) of CH4, with increased concentrations of C6F12O and C3F7H causing faster decreases in the UEL than in the LEL. The explosion limit range of CH4 with C6F12O is smaller than that with C3F7H. When the concentration of CH4 is low, increases in the C6F12O and C3F7H concentrations first cause an increase and then a decrease in the explosion pressure, and the rise rate of explosion pressure increases. After adding the aforementioned FESs, F first increases and then decreases. When the concentration of CH4 is high, the two FESs only inhibit the explosion pressure. Compared with C3F7H, C6F12O has a stronger inhibitory effect; C6F12O has a smaller CH4 explosion triangle area, higher critical oxygen concentration (18.27% vs. 17.70%), and lower F value. Both FESs have promotion and inhibition effects on CH4 explosion because of the comprehensive physical and chemical effects on CH4 explosions; however, the performance of C6F12O is superior to C3F7H. [ABSTRACT FROM AUTHOR]

In this study, underwater electrical explosions of aluminum wires of various sizes were carried out with an initial energy storage of ∼53.5 kJ. Two piezoelectric probes were adopted to record the pressure waveforms. The experiments were divided into different discharge types, and the statistical properties of the electrical and shock-wave parameters of the different discharge types were compared. The experimental results show that there are three discharge types, called type A (breakdown type), type B (transition type), and type C (matched type). The three types differ in the resistance characteristics of the plasma channel during the plasma growth process, which are determined from the average electrical field strength and the remaining energy in the circuit at the peak voltage. Shock waves from type C discharges are more likely to exhibit a higher peak pressure, a larger impulse, and a higher energy density than the other types. However, using a matched wire that matches a specific discharge type, a high peak pressure, large impulse, and high energy density can also be achieved under type A or type B discharges. For example, the maximum peak pressures at ∼33 cm under type B and type C discharges are 38.7 and 42.4 MPa, respectively. These results provide significant guidance for load selection in underwater electrical wire explosion engineering applications. [ABSTRACT FROM AUTHOR]

Explosions of hybrid mixtures are an interesting theoretical and experimental problem in explosion sciences, because they combine the physicochemical properties of flammable gases and dusts. A hybrid mixture is composed of at least two substances in two or more states. The influence of the common presence of flammable gas on the explosiveness parameters of the combustible dust itself is proven. In this study, we present the effect of higher initiation temperatures, different initial sources of initiation with different energies, and the effect of the volume of explosion chambers on the explosions of hybrid mixtures arising from the use of alternative energy sources. The experiments were carried out in 20 L and 1.00 m3 explosion chambers (according to EN 14034-1+A1:2011–EN 14034-4+A1:2011). The accredited method of the Energy Research Centre, VSB-TU Ostrava, for tests was used. The goal is to approximate the behaviour of these systems under different initiation conditions so that it is possible to avoid excessively conservative or overly optimistic results, which then affect the determination of explosion parameters for practical use. It was found that the volume of the explosion chambers in combination with the used initiation source has a fundamental influence on the course of the explosion characteristics. [ABSTRACT FROM AUTHOR]

Shock wave is an important damage element in ammunition explosion and one of the important technical indicators for evaluating its damage power. Accurately measuring shock wave pressure is of great significance for guiding ammunition design and evaluating damage power. The testing environment in the explosion field is harsh, and the measurement of shock wave pressure is affected by various influencing factors, resulting in inaccurate measurement results and low reliability. The location of pressure measurement points directly affects the measurement results of surface reflection pressure and free field pressure. This study is based on the display explosion dynamics simulation software AUTODYN to conduct simulation analysis of the propagation law of explosion shock wave pressure, analyze the height variation of the three wave point trajectory during the ammunition explosion process, and clarify that the surface reflection pressure measurement points need to be located in the Mach reflection zone, and the free field pressure measurement points need to be located above the height of the three wave points. The research results provide theoretical support for accurate testing of explosion shock wave pressure and have significant engineering application value. [ABSTRACT FROM AUTHOR]

Using nearly 20L explosive ball, the effects of various N 2 and CO 2 ratios (5%, 10%, 15%, and 20%) on the explosion characteristics of hydrogen-rich mixtures were studied. The transient emission spectral intensities of H*, OH*, and O* were simultaneously collected in order to compare the influence laws of inert gas on hydrogen explosion from both macroscopic and microscopic aspects. Using the Fundamental Fuel Chemistry Model (FFCM-2), the thermodynamic parameters and exothermic pattern of the reaction were also computed and analyzed. The results are as follows: When the proportion of N 2 is greater than 10%, the explosion pressure rise rate (dp/dt) max is inhibited more clearly; CO 2 has a greater effect than N 2 on the maximum explosion pressure P max and (dp/dt) max of the high equivalency ratio hydrogen explosion; under N 2 , the accumulation of free radicals OH* is greater than that of H* and O*; the reduction of the peak radiation signal intensity I max is significantly greater than the effect of P max ; and CO 2 has a greater effect than N 2 on the adiabatic flame temperature AFT and thermal diffusivity α. CO 2 had a considerably stronger inhibitory effect than N 2 on both α and AFT. [Display omitted] • The suppression of the explosive characteristics under hydrogen-rich conditions is stronger for N 2 ratios higher than 10%. • In N 2 circumstances, the I max of OH* tends to be bigger than that of H* and O*. • The effect of inert gas on I max is significantly larger than the influence on the P max. • CO 2 had a stronger impact on t Imax and t Pmax. [ABSTRACT FROM AUTHOR]

AlH 3 is a promising hydrogen storage material, but poses an explosion risk when suspended in air. Herein, a low-cost and environmentally friendly composite explosion suppressant is prepared using ultrasound coupled cooling crystallization and applied to suppress AlH 3 explosions. Ultrasound-induced cavitation inhibits crystal agglomeration, resulting in fine KH 2 PO 4 crystals growing on the SiO 2 surface by heterogeneous nucleation, which significantly improves the suppression effect. The decomposition products of KH 2 PO 4 react with the flame radicals in the system to generate stable products, interrupting the chain reaction of flame radicals effectively. Furthermore, the complex mesoporous structure of SiO 2 absorbs flame radicals and increases the collision probability between the radicals and the pore walls, thus suppressing flame propagation. Our research provides an important theoretical support for the safe application of light metal hydrogen storage materials. • Fine KH 2 PO 4 crystals grow on the silica surface by heterogeneous nucleation. • SiO 2 adsorbed on the pores of AlH 3 prevents H 2 release, and absorbs flame radicals. • Free radicals from KH 2 PO 4 decomposition interrupt the flame radical chain reaction. [ABSTRACT FROM AUTHOR]

The recently introduced Theory of the Adjacent Possible (TAP) is a model of combinatorial innovation aiming to explain the "hockey-stick" upward trend of human technological evolution, where an explosion in the number of produced items with increasing complexity suddenly occurs. In addition, the TAP model was also used to explain the rapidly emerging biological complexity. Inspired by TAP here we propose a reaction–diffusion system aiming to extend the model in both space and time. We show that the new model exhibits similar characteristics to the TAP model, like the sudden increase in the production of items, after a longer period of slow growth. The new model also exhibits wave propagation of "innovation", resulting in self-sustained complex interference patterns. [ABSTRACT FROM AUTHOR]

Discrimination of underground explosions from naturally occurring earthquakes and other anthropogenic sources is one of the fundamental challenges of nuclear explosion monitoring. In an operational setting, the number of events that can be thoroughly investigated by analysts is limited by available resources. The capability to rapidly screen out events that can be robustly identified as not being explosions is, therefore, of great potential benefit. Nevertheless, possible mis-classification of explosions as earthquakes currently limits the use of screening methods for verification of test-ban treaties. Moment tensors provide a physics-based classification tool for the characterization of different seismic sources and have enabled the advent of new techniques for discriminating between earthquakes and explosions. Following normalization and projection of their six-degree vectors onto the hypersphere, existing screening approaches use spherically symmetric metrics to determine whether any new moment tensor may have been an explosion. Here, we show that populations of moment tensors for both earthquakes and explosions are anisotropically distributed on the hypersphere. Distributions possessing elliptical symmetry, such as the scaled von Mises–Fisher distribution, therefore provide a better description of these populations than the existing spherically symmetric models. We describe a method that uses these elliptical distributions in combination with a Bayesian classifier to achieve successful classification rates of 99 per cent for explosions and 98 per cent for earthquakes using existing catalogues of events from the western United States. The 1983 May 5 Crowdie underground nuclear test and 2018 July 20 DAG-1 deep-borehole chemical explosion are the only two explosions out of 140 that are incorrectly classified. Application of the method to the 2006–2017 nuclear tests in the Democratic People's Republic of Korea yields 100 per cent identification rates and we provide a simple routine MTid for general usage. The approach provides a means to rapidly assess the likelihood of an event being an explosion and can be built into monitoring workflows that rely on simultaneously assessing multiple different discrimination metrics. [ABSTRACT FROM AUTHOR]

The sigmoid functional response in the predator–prey model was posed in 1977. But its dynamics has not been completely characterized. This paper completes the classification of the global dynamics for the classical predator–prey model with the sigmoid functional response, whose denominator has two different zeros. The dynamical phenomena we obtain here include global stability, the existence of the heteroclinic and homoclinic loops, the consecutive canard explosions via relaxation oscillation, and the canard explosion to a homoclinic loop among others. As we know, the last one is a new dynamical phenomenon, which has never been reported previously. In addition, with the help of geometric singular perturbation theory, we solve the problem of connection between stable and unstable manifolds from different singularities, which has not been well settled in the published literature. [ABSTRACT FROM AUTHOR]

In this study, a novel high-speed flyer launching strategy based on electric explosion and laser coupling was proposed to improve the launching ability of electro-explosively actuators and expand the dynamic high-pressure loading method. First, an electro-explosively actuated flyer launcher with a transparent glass substrate was fabricated by microelectromechanical system (MEMS) scale methods, which acted as a carrier to verify the idea of electric explosion and laser coupling. Then, a device of electric explosion combined with laser driving high-speed flyers was established to study the influence of nanosecond pulsed laser on the flyer launching ability of electro-explosively actuators. Finally, the velocity characteristics of the flyer and the plasma characteristics under coupled conditions are studied. The test results indicated that the introduction of laser had a positive effect on increasing the speed of the flyer. In addition, it was found that the acceleration history of the flyer is affected by the energy of electric explosion, laser energy, and the introduction time of laser. [ABSTRACT FROM AUTHOR]

We perform a set of two-dimensional, non-relativistic, hydrodynamics simulations for supernova-like explosions associated with stellar core collapse of rotating massive stars into a system of a black hole and a disc connected by the transfer of matter and angular momentum. Our model of the central engine also includes the contribution of the disc wind. This study is carried out using the open-source hydrodynamic code athena ++ , for which we implement a method to calculate self-gravity for axially symmetric density distributions. We investigate the explosion properties and the 56Ni production of a star with the zero-age main-sequence mass of |$M_\mathrm{ZAMS}=20\, M_\odot$| varying some features of the wind injection. We find a large variety of explosion energy with E expl ranging from ∼0.049 × 1051 to ∼34 × 1051 erg and ejecta mass M ej from 0.58 to 6 M ⊙, which shows a bimodal distribution in high- and low-energy branches. We demonstrate that the resulting outcome of a highly or sub-energetic explosion for a certain stellar structure is mainly determined by the competition between the ram pressure of the injected matter and that of the infalling envelope. In the nucleosynthesis analysis the 56Ni mass produced in our models goes from <0.2  M ⊙ in the sub-energetic explosions to 2.1  M ⊙ in the highly energetic ones. These results are consistent with the observational data of stripped-envelope and high-energy SNe such as broad-lined Type Ic SNe. [ABSTRACT FROM AUTHOR]

Light emission in the first hours and days following core-collapse supernovae (SNe) is dominated by the escape of photons from the expanding shock-heated envelope. In a preceding paper, Paper I, we provided a simple analytic description of the time-dependent luminosity, L , and colour temperature, T col, valid up to H recombination (T ≈ 0.7 eV), for explosions of red supergiants with convective polytropic envelopes without significant circumstellar medium (CSM). The analytic description was calibrated against 'grey' (frequency-independent) photon diffusion numeric calculations. Here, we present the results of a large set of 1D multigroup (frequency-dependent) calculations, for a wide range of progenitor parameters (mass, radius, core/envelope mass ratios, metalicity) and explosion energies, using opacity tables that we constructed (and made publicly available), including the contributions of bound–bound and bound–free transitions. We provide an analytic description of the small, |${\simeq}10\ \hbox{per cent}$| deviations of the spectrum from blackbody at low frequencies, h ν < 3 T col, and an improved (over Paper I) description of 'line dampening' for h ν > 3 T col. We show that the effects of deviations from initial polytropic density distribution are small, and so are the effects of 'expansion opacity' and deviations from LTE ionization and excitation (within our model assumptions). A recent study of a large set of type II SN observations finds that our model accounts well for the early multiband data of more than 50 per cent of observed SNe (the others are likely affected by thick CSM), enabling the inference of progenitor properties, explosion velocity, and relative extinction. [ABSTRACT FROM AUTHOR]

To ensure the safety of the Al powder/H 2 hybrid system in industrial production, the variation law of H 2 explosion parameters under the environment of Al powder with a concentration of 0–150 g/m3 was investigated in the confined container, and feasible hybrid explosion suppression approaches were explored. The results show that with the increasing concentration of Al powder, the explosion intensity of the hybrid systems exhibited an enhancing trend in all cases. The explosion hazard of the hybrid system was most severe when the concentration of H 2 reached stoichiometry. At 30 % H 2 and 150 g/m3 of Al powder, the maximum explosion pressure (P max) of the hybrid system was almost 2.4 times compared to the pure 30 % H 2 explosion. CO 2 -driven silica/sodium phytate (SiO 2 /PA-Na) suppressed explosions more effectively than N 2 -driven SiO 2 /PA-Na. As the mass fraction of SiO 2 /PA-Na was increased to 50 wt%, the CO 2 -driven solid inhibitors decreased the P max and deflagration index (K st) of the hybrid system by 60.9 % and 90.1 %, respectively, and the delay of the time to peak explosion pressure (T p) was elevated to 306.4 %. Furthermore, it was revealed that the multi-component inhibitors suppressed the Al powder/H 2 hybrid explosion mainly through comprehensive effects such as adsorption of heat, dilution of oxygen, disruption of chain reactions, and isolation reactants. This study contributes to the enrichment of experimental evidence of Al powder/H 2 hybrid explosion and the precise development of efficient explosion prevention technology. • The explosion behavior of H 2 involving five low concentrations of Al powder was explored. • 30 % H 2 mixed with low concentrations of Al powder presented a substantial explosion hazard. • CO 2 -driven SiO 2 /PA-Na exhibited a better suppression effect than N 2 -driven SiO 2 /PA-Na. • The synergistic suppression mechanism of multi-component inhibitors was elucidated. [ABSTRACT FROM AUTHOR]

This paper presents the results for a model of a typical urban compressed natural gas (CNG) station obtained with the help of numerical methods on the assumption that the leakage explosion scenarios run under three orifice sizes. The simulation demonstrates that the CNG leak rate is quite high and the leaking gas cloud spreads quickly along the ground, increasing the vertical diffusion speed. As a result, longitudinal space becomes the main area of hazard. The hazard explosion overpressure is concentrated mainly in the narrow area between the tank and surrounding buildings, and the maximum explosion overpressure exceeds 0.4 bar. The range of the overpressure hazard will cover the entire gas station where a shock wave, high temperature, and flame damage may occur, but projectile strikes may exceed this range, and the risk of explosion becomes higher. In addition, the attenuation of the overpressure by the wall is significant, and the maximum attenuation rate can reach 65%. [ABSTRACT FROM AUTHOR]

Recent developments in multi-dimensional simulations of core-collapse supernovae have considerably improved our understanding of this complex phenomenon. In addition to that, one-dimensional (1D) studies have been employed to study the explosion mechanism and its causal connection to the pre-collapse structure of the star, as well as to explore the vast parameter space of supernovae. Nonetheless, many uncertainties still affect the late stages of the evolution of massive stars, their collapse, and the subsequent shock propagation. In this review, we will briefly summarize the state-of-the-art of both 1D and 3D simulations and how they can be employed to study the evolution of massive stars, supernova explosions, and shock propagation, focusing on the uncertainties that affect each of these phases. Finally, we will illustrate the typical nucleosynthesis products that emerge from the explosion. [ABSTRACT FROM AUTHOR]

Explosions of droplets that are caused by superheating of the liquid phase occur in many combustion processes but are difficult to investigate experimentally. We have studied this process for nanodroplets using non-equilibrium molecular dynamics simulations. Starting from an equilibrium state in which a spherical droplet is surrounded by a vapor phase, a local thermostat is used to impose a high temperature in a small control volume in the droplet center and the following process is studied for varying set temperatures. The fluid is modeled using the Lennard–Jones truncated and shifted potential. Depending on the set temperature, three different system responses were observed: (i) Low set temperatures lead to a shrinking of the droplet due to evaporation that follows the well-known d2 law. (ii) At intermediate set temperatures, a vapor bubble emerges in the droplet center and the liquid phase is formed into spherical shell that expands as the bubble inside of it grows. However, that spherical shell is only temporarily stable and eventually breaks apart. (iii) For high set temperatures, the abrupt and violent formation of the vapor bubble leads to an immediate breakup of the droplet. For case (ii), unexpected phenomena were observed. Oscillations in the diameter of the vapor bubble surrounded by the liquid film occurred. In some simulations, small holes formed temporarily in the liquid shell during its expansion, which closed again over the course of the simulation. Moreover, for one specific set temperature, a transition of the spherical droplet shell into a torus-like object was observed. [ABSTRACT FROM AUTHOR]

In this paper, we analyze a quasi-linear parabolic initial-boundary problem describing the thermal explosion of a compressible micropolar real gas in one spatial dimension. The model contains five variables, mass density, velocity, microrotation, temperature, and the mass fraction of unburned fuel, while the associated problem contains homogeneous boundary conditions. The aim of this work is to prove the uniqueness theorem of the generalized solution for the mentioned initial-boundary problem. The uniqueness of the solution, together with the proven existence of the solution, makes the described initial-boundary problem theoretically consistent, which provides a basis for the development of numerical methods and the engineering application of the model. [ABSTRACT FROM AUTHOR]

This work focused on the production of the MoAlB MAB phase through self-propagating, high-temperature synthesis in the thermal explosion mode. The influence of the method of a Mo-Al-B-powder reaction mixture preparation on the combustion temperature, mechanism, and stages of the MAB phase formation in the combustion process was investigated. The combustion temperatures of the mixtures obtained in the rotary ball mill and high-speed planetary ball mill were 1234 and 992 °C, respectively. The formation of intermediate compounds Mo3Al8 and α-MoB in the combustion front, along with MoAlB, was established using the time-resolved X-ray diffraction method. In the case of the mixture prepared in a ball mill, the primary interaction in the combustion front occurred through the Al melt, and in the case of using a planetary mill, solid-phase reactions played an important role. The mechanical activation of the mixture in a planetary mill also accelerated the processes of phase formation. The method of a reaction mixture preparation has virtually no effect on the MoAlB MAB phase content in combustion products (92–94%), but it does affect their structure. The synthesis products have a lamellar structure composed of MAB grains with a thickness of ~0.4 μm and a length of ~2–10 μm. [ABSTRACT FROM AUTHOR]

We present photometric, spectroscopic, and polarimetric observations of the intermediate-luminosity Type IIP supernova (SN) 2021gmj from 1 to 386 d after the explosion. The peak absolute V -band magnitude of SN 2021gmj is −15.5 mag, which is fainter than that of normal Type IIP SNe. The spectral evolution of SN 2021gmj resembles that of other sub-luminous SNe: The optical spectra show narrow P-Cygni profiles, indicating a low expansion velocity. We estimate the progenitor mass to be about 12  |$\rm {\rm M}_{\odot}$| from the nebular spectrum and the 56Ni mass to be about 0.02 |$\rm {\rm M}_{\odot}$| from the bolometric light curve. We also derive the explosion energy to be about 3 × 1050 erg by comparing numerical light-curve models with the observed light curves. Polarization in the plateau phase is not very large, suggesting nearly spherical outer envelope. The early photometric observations capture the rapid rise of the light curve, which is likely due to the interaction with a circumstellar material (CSM). The broad emission feature formed by highly ionized lines on top of a blue continuum in the earliest spectrum gives further indication of the CSM at the vicinity of the progenitor. Our work suggests that a relatively low-mass progenitor of an intermediate-luminosity Type IIP SN can also experience an enhanced mass-loss just before the explosion, as suggested for normal Type IIP SNe. [ABSTRACT FROM AUTHOR]

In the current study, effects of vent area and ignition location on vented stoichiometric hydrogen-air mixture explosion were experimentally and numerically investigated. Internal and external pressure-time curves and flame behavior were focused. For low vent coefficient K v = 4, the maximum internal pressure results from the vent rupture for front ignition and the external explosion for center ignition and rear ignition. The maximum internal pressure for IL4 is larger than those for other ignition locations. The maximum internal pressure is induced by the internal chemical reaction and increases monotonically with K v for different ignition locations, and the maximum internal pressure occurs at center ignition as K v ＞ 4. Mach disk in external flame begins to appear when K v increases to 12.75 for front ignition and 8.65 for other ignition locations. External pressure histories show two pressure peaks P 1 and P 2 for center and rear ignitions. Although the pressure peak P 1 results from the leading pressure wave, the pressure peak P 2 is induced by the venting flame and external explosion for center ignition and rear ignition, respectively. Only one pressure peak was recorded for center ignition. For front ignition and IL2 , the maximum external pressure increases with K v while it firstly increases and then decreases for center ignition, IL4 and rear ignition, the critical value is K v = 17.36 for center ignition and IL4 while it is K v = 8.65 for rear ignition. [ABSTRACT FROM AUTHOR]

The surface reflection pressure sensor installation flatness will directly lead to the change of the explosion shock wave pressure propagation and distribution law, affecting the test results accuracy, and the test data cannot accurately evaluate the ammunition explosion damage power. In this study, the numerical simulation model of the explosion shock wave pressure propagation and distribution law was established by using the explosive mechanics simulation software, and the pressure distribution law was studied when the sensors installation angles were 0°, 4°, 8°, 12°, −4°, −8°, and −12° respectively. Combined with analysis of the pressure peak value and the pressure evolution nephogram at different measuring points, it is clarified that the positive tilt angle of the sensor installation has an enhancing effect on the pressure peak, while the negative tilt angle has a attenuation effect on the pressure peak. Based on the calculation function formula of the surface reflected pressure peak value in the national defense engineering design code, the surface reflected pressure peak value correction function formula is established by introducing the sensor installation angle correction effect. This study results provide a theoretical basis for the design of ammunition explosion shock wave pressure engineering test scheme and the test data validity verification. [ABSTRACT FROM AUTHOR]

Summary: This study aimed to recover protein hydrolysate from chicken bone by steam explosion and investigate its calcium‐binding capacity and potential pro‐osteogenic activity. The results showed that the recovery rate was significantly affected by pressure, time, and filling ratio. The molecular weight distribution and amino acid composition of the protein hydrolysate were also analysed. Furthermore, the protein hydrolysate extracted at 12 min, 1.8 MPa and 40% filling ratio showed well calcium‐binding capacity, and the peptides‐calcium chelate showed good stability at different temperatures. The cell experiment showed that the peptides‐calcium chelate can significantly improve the osteogenic activity of MC3T3‐E1 cells, including the proliferation, differentiation, and mineralisation. In conclusion, the steam explosion was an effective strategy to recover protein hydrolysate with well calcium‐binding capacity and potential pro‐osteogenic activity from chicken bone. This study provided new insights and theoretical bases for the application of steam explosion in extracting protein hydrolysate to improve bone health. [ABSTRACT FROM AUTHOR]

To assess the consequences of hydrogen leakage, subsequent combustion, and resulting explosions within confined spaces such as ducts and channels and to reveal the combustion and explosion characteristics and influencing mechanisms of hydrogen, a rectangular test tube with a pressure rating of 10 MPa and a large aspect ratio of 120 was designed. The purpose of this study was to simulate the flame propagation and overpressure characteristics of hydrogen-air mixtures ignited in rectangular channels with large aspect ratios under atmospheric pressure. The effects of the hydrogen volume fraction (20%–45 %) and pipe blockage ratio (0/0.4) on the hydrogen combustion and explosion processes were analyzed. The results show that, under both smooth tube and obstacle installation conditions, increasing the hydrogen volume fraction from 20 % to 25 % resulted in 367.6 % and 63 % increases in explosion overpressure, respectively. The presence of obstacles considerably increases the explosion overpressure, and the position of the highest overpressure moves from downstream to upstream of the explosion outlet. Within the range of 25%–45 % hydrogen volume fraction, the overpressure exceeded the theoretical detonation pressure. At a hydrogen volume fraction of 35 %, the highest overpressure reached 2899 kPa, which was approximately twice that of the smooth tube. At a hydrogen volume fraction of 40 %, the maximum range of overdriven detonation was observed in the tube. • Hydrogen's explosion characteristics were investigated in a large-aspect-ratio tube. • The effects of the hydrogen volume fraction and pipe blockage ratio were analyzed. • The maximum overpressure in the obstructed tube is approximately twice that of the smooth tube. • The overpressure exceeds the theoretical detonation pressure with 25%–45 % hydrogen addition. [ABSTRACT FROM AUTHOR]

In this work, the explosion of hydrogen/nitrous oxide/carbon dioxide mixtures with various equivalence ratios (0.6–1.0), initial pressures (40–100 kPa), and carbon dioxide fractions (20%–40 %) at ambient temperature (298 K) was conducted inside a normative 15.625-L cubic container. The maximum explosion pressure and pressure rise speed were obtained and analyzed. The results show that carbon dioxide plays a crucial role in weakening H 2 /N 2 O explosion intensity, flame instabilities, as well as the tendency of deflagration to detonation. In addition, the addition of carbon dioxide has affected the two competitive effects between adiabatic temperature and molecular number. The variations of maximum explosion pressure and pressure rise speed with equivalence ratios depend on the carbon dioxide fraction. Only a linear dependence was found between maximum pressure rise speed and original pressure. These results would be useful in developing explosion-proof devices in the event of potential fire and explosion hazards. • Highlights (for review). • Carbon dioxide plays a significant role in weakening H 2 /N 2 O explosion intensity. • The variations of (d p /d t) max - φ depend on the carbon dioxide fraction. • The competitive effects between adiabatic temperature and molecular number are affected by CO 2. • The addition of CO2 effectively suppresses the tendency of deflagration to detonation. [ABSTRACT FROM AUTHOR]

As one of the potential explosions and inflammation, compressed natural gas (CNG) stations in urban areas cause irreparable losses and casualties. Estimating risk assessment in gas stress based on coherent uses can reduce accidents in urban areas. The purpose of the present study was to estimate a small risk estimation at one of the CNG multipurpose stations, LPG, using combined models of the Fuzzy Bayesian Network, Bow-tie Diagram, and consequence modeling. This study was conducted based on the basic and 25 intermediate events. This study formed a seven-person safety team to identify the primary events and build the Bow-tie diagram. Then, because of the lack of a proper database, fuzzy theory was used to determine the probability of significant events. Bayesian networks were drawn based on the Bow-tie model using GeNLe software. Finally, the main events of the two Bow-tie, Bayesian network modeling, and risk estimation were performed with the help of PHAST/SAFETI (V8.22). The geographical information system software was used to zone the explosion effects. The Risk assessment result showed that the social risks and the Bayesian network model are more than Bow-tie, and the Bow-tie diagram is unacceptable. Therefore, using incompatible land uses in the vicinity of the CNG stations gives rise to the effects of accident scenarios in particular residential and administrative land uses, which decision-makers and city managers should consider. Based on the findings of this study, the obtained results can be utilized to implement effective control measures. These measures encompass devising a response plan tailored to address specific emergency conditions and conducting comprehensive training programs for the individuals and residents residing within the study area. [ABSTRACT FROM AUTHOR]

An experimental study of premixed syngas/air flame explosive characteristics in an obstacle pipe is introduced. Square obstacles with a blocking rate of 0.5 are installed at varying positions from the ignition end inside a closed pipe to conduct syngas-air explosion dynamics experiment with varying equivalence ratios (Φ) and obstacle positions (OP). Results show that compared to OP = 150 mm, the tulip flame will form at OP = 450 mm and OP = 750 mm. The distribution of flame front velocity and overpressure have same trend in the process of flame oscillation. Nevertheless, the overpressure curve will produce oscillation when the flame propagates out of the pipe at OP = 450 mm. As the increase of OP, the maximum flame front velocity first increases and then decreases and the maximum overpressure decreases gradually. Both the maximum flame front velocity and maximum overpressure first increase then decrease with Φ, reaching the maximum at Φ = 1.4. This research can provide some suggestions when syngas-air fuels are applied in the presence of obstacles. • The maximum overpressure and flame front velocity reach the maximum at Φ = 1.4. • The pressure oscillation is most pronounced at OP = 450 mm. • The distribution of flame front velocity and overpressure have same trend. • The maximum flame front velocity reaches the maximum at OP = 450 mm. • The maximum overpressure reaches the maximum at OP = 150 mm. [ABSTRACT FROM AUTHOR]

The effect of varying CO 2 addition ratios (λ) on the internal and external pressure characteristics of vented hydrogen-air explosions with an equivalent ratio of 1.5 at elevated static activation pressures (P stat) of 0.5–2.5 bar was experimentally investigated. The results showed that the inerting effect of CO 2 improved the effectiveness of the venting and allowed equilibrium venting at small vent areas and elevated P stat , further improving the stability and reliability of the hydrogen-air explosive venting technique. However, it was recognized that increasing the CO 2 content beyond 10–15% tended to decrease the effectiveness of the maximum pressure rise rate reduction. For external pressure, the peak external explosion pressures decreased significantly as the λ increased. At a fixed λ , the peak external explosion pressure increased and then decreased as the P stat increased, reaching a peak at 2.0 bar. Based on the laminar flame venting mechanism, a predictive model for the equilibrium venting area with coupled inerting and venting effects was developed. The pseudo-source theory was introduced to establish a model that allowed estimating the peaks of external explosion pressures at elevated P stat. [Display omitted] • Internal and external pressure characteristics of vented explosions were analyzed. • The inerting effect improved the effectiveness and reliability of the venting. • A model for the equilibrium venting area with coupled inerting was developed. • A model based on pseudo-source theory for external explosion pressure was proposed. [ABSTRACT FROM AUTHOR]

As one of the potential explosions and inflammation, compressed natural gas (CNG) stations in urban areas cause irreparable losses and casualties. Estimating risk assessment in gas stress based on coherent uses can reduce accidents in urban areas. The purpose of the present study was to estimate a small risk estimation at one of the CNG multipurpose stations, LPG, using combined models of the Fuzzy Bayesian Network, Bow-tie Diagram, and consequence modeling. This study was conducted based on the basic and 25 intermediate events. This study formed a seven-person safety team to identify the primary events and build the Bow-tie diagram. Then, because of the lack of a proper database, fuzzy theory was used to determine the probability of significant events. Bayesian networks were drawn based on the Bow-tie model using GeNLe software. Finally, the main events of the two Bow-tie, Bayesian network modeling, and risk estimation were performed with the help of PHAST/SAFETI (V8.22). The geographical information system software was used to zone the explosion effects. The Risk assessment result showed that the social risks and the Bayesian network model are more than Bow-tie, and the Bow-tie diagram is unacceptable. Therefore, using incompatible land uses in the vicinity of the CNG stations gives rise to the effects of accident scenarios in particular residential and administrative land uses, which decision-makers and city managers should consider. Based on the findings of this study, the obtained results can be utilized to implement effective control measures. These measures encompass devising a response plan tailored to address specific emergency conditions and conducting comprehensive training programs for the individuals and residents residing within the study area. [ABSTRACT FROM AUTHOR]

Most massive stars end their lives with core collapse. However, it is not clear which explode as a core-collapse supernova (CCSN), leaving behind a neutron star, and which collapse to a black hole, aborting the explosion. One path to predict explodability without expensive multidimensional simulations is to develop analytic explosion conditions. These analytic conditions also provide a deeper understanding of the explosion mechanism and they provide some insight into why some simulations explode and some do not. The analytic force explosion condition (FEC) reproduces the explosion conditions of spherically symmetric CCSN simulations. In this follow-up manuscript, we include the dominant multidimensional effect that aids explosion—neutrino-driven convection—in the FEC. This generalized critical condition (FEC+) is suitable for multidimensional simulations and has potential to accurately predict explosion conditions of two- and three-dimensional CCSN simulations. We show that adding neutrino-driven convection reduces the critical condition by ∼30%, which is consistent with previous multidimensional simulations. [ABSTRACT FROM AUTHOR]

The object of the study is the sound accompaniment of the processes of stress redistribution in the bottom part of the coal seam, which precede the release of rock, coal, and gas. Among the hazards of underground coal mining, gas-dynamic phenomena (GDP) are the most complex in nature and the most dangerous in terms of consequences of high dynamic power and the release of a large amount of mechanical energy in the form of fractures and gas in a short period of time. This leads to accidents due to sudden gassing and blockages of workings with coal and rock, as well as explosions of methane and coal dust, destruction of the workings’ support, damage to machinery and mechanisms, equipment, and devices. The greatest hazard among GDPs is posed by sudden releases of coal and gas, rock and gas, gas releases with destruction of host rocks and with destruction of the ground of the workings, as well as gas breakthroughs from tectonic fault zones. Therefore, the accuracy of predicting possible gas-dynamic phenomena significantly affects the level of safety of miners. The acoustic emission (AE) method is used to predict the gas-dynamic activity of a rock massif. The analysis of acoustic emission studies based on archival data in coal seams subject to gas-dynamic activity has made it possible to substantiate the possibility of improving the accuracy of the forecast of emission hazard, which has a social and economic effect. On the basis of exploratory research and production tests, the software for automated calculations of the GDP forecast was improved and an improved Methodology for forecasting gas-dynamic phenomena based on modern sound-capturing equipment was developed. A scientific justification for the reference interval of AE observations in the conditions of a particular longwall was developed. The developed software and the forecasting methodology were tested in the conditions of the Tsentralna mine of the Toretskugol State Enterprise (Toretsk, Donetsk region, Ukraine). The practical significance of the work is that a method for predicting explosion hazard has been developed, taking into account the modern capabilities of equipment and methods of input data processing, which allows to increase the productivity of mining and tunneling operations in coal seams without reducing the safety of miners. [ABSTRACT FROM AUTHOR]