Hasil untuk "Explosives and pyrotechnics"

Wei Ren, Dongpeng Zhang, Enyi Chu et al.

As the initial energetic device and driving force of weapon systems, pyrotechnics serve as the core and most sensitive explosive initiating device of weaponry. To accommodate the development requirements of various informatized and miniaturized weapons, MEMS pyrotechnics, characterized primarily by energy conversion informatization, structural miniaturization, and train integration, have become a significant direction in the development of pyrotechnics technology. MEMS Safety and Arming Devices, serving as the energy transfer control mechanisms for micro-explosive trains in MEMS pyrotechnics, are one of the key technologies in the design of MEMS pyrotechnics. This study conducted a classification study of a silicon-based MEMS Safety and Arming Device from the perspective of micro-explosive train structures, analyzed the technical principles of different S&A device, explored their application progress and research status, and summarizes the trends of the micro-miniaturization, integration, and informatization of the silicon-based MEMS Safety and Arming Device, providing new ideas for the research and the design of MEMS Safety and Arming Devices.

Ana Sainz de Murieta, Mark R. Magee, Tian Li et al.

The magnification resulting from strong gravitational lensing is a powerful tool to add new constraints to the cosmic evolution of supernova progenitors by enabling the study of distant supernovae that would otherwise not be observable. iPTF16geu is the most well-observed gravitationally lensed supernova (glSN) to date. At a redshift of $z = 0.409$ and magnified by a factor of $\sim$68, extensive photometric and spectroscopic observations have been obtained. The explosion mechanism producing this rare event and differences compared to lower redshift supernovae however have not been explored in detail. Here we compare observations of iPTF16geu to existing radiative transfer simulations of type Ia supernova explosion models selected from the literature. We find that overall the DDC6, PDDEL1, and N10 models produce the closest match to the light curves and many absorption features, providing some evidence in favour of the delayed detonation scenario. All models struggle however to replicate the observed colours and in particular the rest-frame UV. We also investigate the magnification and reddening values required to improve agreement with the selected models. Upcoming surveys will significantly increase the samples of SNe discovered at high redshifts due to strong gravitational lensing. These glSNe will enable tighter constraints on the explosion physics of type Ia supernovae and how this has evolved throughout the Universe.

Maria Fueth, Simon Bausen, S. Schmidt et al.

Firework-related injuries remain a serious public health issue in Germany, especially during New Year’s Eve. While many injuries are minor, the misuse of illegal or homemade fireworks can cause severe trauma resembling military combat injuries and can heavily burden emergency services. Notably, injury rates declined during the COVID-19 firework bans, underscoring the impact of preventive measures. We report two cases of young males with severe injuries from illicit fireworks. The first is a case of a 16-year-old that detonated an illegal Polish firework ball bomb, sustaining 9% total body surface area (TBSA) burns (second- to third-degree), hand fractures, compartment syndrome of the hand, and soft-tissue trauma. He underwent multiple surgeries, including fasciotomy, osteosynthesis, and skin grafting. The other case presented is a 19-year-old man who was injured by a homemade device made of bundled firecrackers, suffering deep facial and bilateral hand burns. He required prolonged ventilation, surgical debridement, and treatment with Kerecis® fish skin and Epicite® dressings. Both required intensive ICU care, interdisciplinary management, and lengthy rehabilitation. Total hospital costs amounted to €58,459.52 and €94,230.23, respectively, as calculated according to the standardized German DRG. These cases illustrate the devastating impact of illegal fireworks. The devastating consequences of explosive trauma are often difficult to treat and may lead to long-term functional and psychological impairments. Prevention through public education, stricter regulations, and preparedness is essential. Pandemic-era injury reductions support sustained policy efforts.

Rene Francisco B Gonçalves, F. B. Mendonça, J. A. Rocco

The N5⁻ anion, known as pentazolate, represents a groundbreaking advancement in the field of energetic materials, offering promising applications in rocket propulsion, explosive devices, and pyrotechnics. Comprising five nitrogen atoms arranged in a cyclic structure with a negative charge, has captured significant interest due to its unique configuration and high energy potential. In this article, we provide a comprehensive overview of the N5⁻ anion's potential as an energetic material, alongside the role of RMD simulations in elucidating its behavior. The ReaxFF forcefield was used to simulate the materials pyrolysis. The total energy behavior of different species containing pentazolate, across a range of temperatures (1500 K to 3000 K) revealed distinct trends and characteristics associated with the thermal dynamics and stability of the molecule under varying thermal conditions. Their mechanisms were elucidated, and the kinetic parameters were calculated, indicating that CNN5, with its low activation energy (39.14 kJ/mol), stands out as the most reactive, while PolyN5, with the highest activation energy (52.88 kJ/mol), is the most stable. Overall, the N5 - anion represents a promising avenue for the development of high-energy materials.

Linna Li, Han Gao, Junyi Lu et al.

Pyrotechnic detection has always been one of the critical issues in blasting safety. Due to the complex environment of blasting sites, irregular detonator wire postures, and the differences in object scales, making the detection of pyrotechnics more challenging. To address these challenges, this paper proposes an improved algorithm based on a multi-scale parallel attention mechanism and wavelet-separable convolution, called WA-YOLO. First, we integrate wavelet convolution into depthwise separable convolution and propose a novel convolutional block (WSDConv, Wavelet Separable Depthwise Convolution). This new convolutional block is added to the model’s backbone, improving feature extraction while also lowering computational parameters. Furthermore, we introduce an improved Cross Stage Partial (CSP) structure by combining multi-scale convolutions with a parallel attention mechanism, embedding it into the C2f module of the neck network to improve the model’s ability to detect objects of varying scales in complex backgrounds. To tackle the detection accuracy drop caused by the irregular shapes and varying aspect ratios of detonator wires, the model uses the Wise-IoU loss function. This enhances the model’s generalization and robustness by improving the precision of overlap calculations for bounding boxes. The experimental results show that the improved model achieved an average precision increase of 12.6% on the self-built dataset, particularly with an average precision increase of 8.3% in the detection of detonators. Additionally, the model performance also improved on the VOC2012 dataset, with a recall increase of 1.3% and an average precision increase of 1.6%. These results indicate that the proposed model exhibits strong generalization capabilities, can work effectively across different datasets, and provides an effective solution to the challenges of target detection in blasting environments.

Ramesh S. Bhavi, Sivakumar Sudarsanan, Manikandan Raghunathan et al.

A sudden transition to a state of high amplitude limit cycle oscillations is catastrophic in a thermo-fluid system. Conventionally, upon varying the control parameter, a sudden transition is observed as an abrupt jump in the amplitude of the fluctuations in these systems. In contrast, we present an experimental discovery of a canard explosion in a turbulent reactive flow system where we observe a continuous bifurcation with a rapid rise in the amplitude of the fluctuations within a narrow range of control parameters. The observed transition is facilitated via a state of bursting, consisting of the epochs of large amplitude periodic oscillations amidst the epochs of low amplitude periodic oscillations. The amplitude of the bursts is higher than the amplitude of the bursts of intermittency state in a conventional gradual transition, as reported in turbulent reactive flow systems. During the bursting state, we observe that temperature fluctuations of exhaust gas vary at a slower time scale in correlation with the amplitude envelope of the bursts. We also present a phenomenological model for thermoacoustic systems to describe the observed canard explosion. Using the model, we explain that the large amplitude bursts occur due to the slow-fast dynamics at the bifurcation regime of the canard explosion.

Gabriel Lacerda, Sergio Romaña

Given $X$ a compact metric space and $T: X \to X$ a continuous map, the induced hyperspace map $T_\mathcal{K}$ acts on the hyperspace $\mathcal{K}(X)$ of closed and nonempty subsets of $X$, and on the continuum hyperspace $\mathcal{C}(X) \subset \mathcal{K}(X)$ of connected sets. This work studies the mean dimension explosion phenomenon: when the base system $T$ has zero topological entropy, but the mean dimension of the induced map $T_\mathcal{K}$ is infinite. In particular, this phenomenon occurs for Morse-Smale diffeomorphisms. Furthermore, for a circle homeomorphism $H$, the mean dimension explosion does not occur if and only if $H$ is conjugate to a rotation. For the metric mean dimension, a different result is obtained: we establish sufficient conditions for the induced hyperspace map to have zero or infinite metric mean dimension.

Dmitry Shishkin, Noam Soker

We examine the binding energies of massive stripped-envelope core collapse supernova (SECCSN) progenitors with the stellar evolution code MESA, and find that the jittering jets explosion mechanism is preferred for explosions where carbon-oxygen cores with masses of $>20 M_\odot$ collapse to leave a neutron star (NS) remnant. We calculate the binding energy at core collapse under the assumption that the remnant is a NS. Namely, stellar gas above mass coordinate of $~1.5-2.5 M_\odot$ is ejected in the explosion. We find that the typical binding energy of the ejecta of stripped-envelope progenitors with carbon-oxygen core masses of $M_{CO} > 20 M_\odot$ is $E_{bind}>2 \times 10^{51} erg$. We claim that jets are most likely to explode such cores as jet-driven explosion mechanisms can supply high energies to the explosion. We apply our results to SN 2020qlb, which is a SECCSN with a claimed core mass of $~30-50 M_\odot$, and conclude that the jittering jets explosion mechanism best accounts for such an explosion that leaves a NS.

Jaume Ojer, Michele Starnini, Romualdo Pastor-Satorras

Understanding the dynamics of opinion depolarization is pivotal to reducing the political divide in our society. We propose an opinion dynamics model, which we name the social compass model, for interdependent topics represented in a polar space, where zealots holding extreme opinions are less prone to change their minds. We analytically show that the phase transition from polarization to consensus, as a function of increasing social influence, is explosive if topics are not correlated. We validate our theoretical framework through extensive numerical simulations and recover explosive depolarization also by using initial opinions from the American National Election Studies, including polarized and interdependent topics.

Benny T. -H. Tsang, David Vartanyan, Adam Burrows

Most existing criteria derived from progenitor properties of core-collapse supernovae are not very accurate in predicting explosion outcomes. We present a novel look at identifying the explosion outcome of core-collapse supernovae using a machine learning approach. Informed by a sample of 100 2D axisymmetric supernova simulations evolved with Fornax, we train and evaluate a random forest classifier as an explosion predictor. Furthermore, we examine physics-based feature sets including the compactness parameter, the Ertl condition, and a newly developed set that characterizes the silicon/oxygen interface. With over 1500 supernovae progenitors from 9$-$27 M$_{\odot}$, we additionally train an auto-encoder to extract physics-agnostic features directly from the progenitor density profiles. We find that the density profiles alone contain meaningful information regarding their explodability. Both the silicon/oxygen and auto-encoder features predict explosion outcome with $\approx$90\% accuracy. In anticipation of much larger multi-dimensional simulation sets, we identify future directions in which machine learning applications will be useful beyond explosion outcome prediction.

A. Aburto-Medina, E. Shahsavari, M. Taha et al.

The dinitrotoluene isomers 2,4 and 2,6-dinitrotoluene (DNT) represent highly toxic, mutagenic, and carcinogenic compounds used in explosive manufacturing and in commercial production of polyurethane foam. Bioremediation, the use of microbes to degrade residual DNT in industry wastewaters, represents a promising, low cost and environmentally friendly alternative technology to landfilling. In the present study, the effect of different bioremediation strategies on the degradation of DNT in a microcosm-based study was evaluated. Biostimulation of the indigenous microbial community with sulphur phosphate (2.3 g/kg sludge) enhanced DNT transformation (82% transformation, from 300 g/L at Day 0 to 55 g/L in week 6) compared to natural attenuation over the same period at 25 °C. The indigenous microbial activity was found to be capable of transforming the contaminant, with around 70% transformation of DNT occurring over the microcosm study. 16S rDNA sequence analysis revealed that while the original bacterial community was dominated by Gammaproteobacteria (30%), the addition of sulphur phosphate significantly increased the abundance of Betaproteobacteria by the end of the biostimulation treatment, with the bacterial community dominated by Burkholderia (46%) followed by Rhodanobacter, Acidovorax and Pseudomonas. In summary, the results suggest biostimulation as a treatment choice for the remediation of dinitrotoluenes and explosives waste.

Apoorva Purohit, Kirill A. Velizhanin

The kinetics of carbon condensation, or carbon clustering, in detonation of carbon-rich high explosives is modeled by solving a system of rate equations for concentrations of carbon particles. Unlike previous efforts, the rate equations account not only for the aggregation of particles, but also for their fragmentation in a thermodynamically consistent manner. Numerical simulations are performed, yielding the distribution of particle concentrations as a function of time. In addition to that, analytical expressions are obtained for all the distinct steps and regimes of the condensation kinetics, which facilitates the analysis of the numerical results and allows one to study the sensitivity of the kinetic behavior to the variation of system parameters. The latter is important because the numerical values of many parameters are not reliably known at present. The theory of the kinetics of first-order phase transitions is found adequate to describe the general kinetic trends of carbon condensation, as described by the rate equations. Such physical phenomena and processes as the coagulation, nucleation, growth, and Ostwald ripening are observed and their dependence on various system parameters is studied and reported. It is believed that the present work will become useful when analyzing the present and future results for the kinetics of carbon condensation, obtained from experiments or atomistic simulations.

Evgeni Grishin, Alexey Bobrick, Ryosuke Hirai et al.

Active galactic nuclei (AGN) are prominent environments for stellar capture, growth and formation. These environments may catalyze stellar mergers and explosive transients, such as thermonuclear and core-collapse supernovae (SNe). SN explosions in AGN discs generate strong shocks, leading to unique observable signatures. We develop an analytical model which follows the evolution of the shock propagating in the disc until it eventually breaks out. We derive the peak luminosity, bolometric lightcurve, and breakout time. The peak luminosities may exceed $10^{45}$ erg s$^{-1}$ and last from hours to days. The brightest explosions occur in regions of reduced density; either off-plane, or in discs around low-mass central black holes ($\sim 10^6\ M_\odot$), or in starved subluminous AGNs. Explosions in the latter two sites are easier to observe due to a reduced AGN background luminosity. We perform suites of 1D Lagrangian radiative hydrodynamics SNEC code simulations to validate our results and obtain the luminosity in different bands, and 2D axisymmetric Eulerian hydrodynamics code HORMONE simulations to study the morphology of the ejecta and its deviation from spherical symmetry. The observed signature is expected to be a bright blue, UV, or X-ray flare on top of the AGN luminosity from the initial shock breakout, while the subsequent red part of the lightcurve will largely be unobservable. We estimate the upper limit for the total event rate to be $\mathcal{R}\lesssim 100\ \rm yr^{-1}\ Gpc^{-3}$ for optimal conditions and discuss the large uncertainties in this estimate. Future high-cadence transient searches may reveal these events. Some existing tidal disruption event candidates may originate from AGN supernovae.

Shannon T. Krauss, T. P. Forbes, Dillon Jobes

Ting-Chung Wang, Jinyang Zhou, Qi Zhang et al.

In this paper, an ingenious strategy based on constructing energetic metal–organic frameworks (EMOFs) with cesium salts for new green and practical pyrotechnic composition is described. In order to obtain a non-hygroscopic, chlorine-free formulation, a novel triazole nitrogen-rich energetic ligand, N-(5′-amino-1H,1′H-[3,3′-bi(1,2,4-triazol)]-5-yl)nitramine (HABTNA), was designed and synthesized, which exhibited some good properties such as insensitivity, high nitrogen content and energy, and excellent oxygen balance. More importantly, using this triazole ligand and cesium(I) salts, an energetic metal–organic framework (EMOF) structure as a pyrotechnic colorant was built by a simple and green aqueous solution crystallization method. The results of single-crystal X-ray diffraction experiments indicated that this EMOF has a compact three-dimensional structure with high density. Physical and chemical property tests revealed that this Cs(I)-based MOF has excellent moisture resistance and thermal stability, while, at the same time, it was also proved to be a high-energy insensitive energetic material with energy up to the explosive level. By a systematic pyrotechnic performance experiment, a chlorine-free pyrotechnic formulation with this flammable EMOF as the main component was developed, which was the first orange-light-emitting pyrotechnic formulation with high color purity and intensity.

Kathryn R. Chabaud, Jennifer L. Thomas, Michelle N. Torres et al.

Abstract A microfluidic paper-based analytical device (µPAD) has been developed for the onsite determination of low explosives residues. The device is capable of simultaneous detection of a variety of metallic salts using colorimetric detection. The µPAD was printed on chromatography paper with wax ink, allowing for the creation of a set of hydrophobic channels. Each channel contains a specific set of reagents that yields a color change upon interaction with a specific metal salt. The device is capable of performing six simultaneous tests, including the detection of metallic salts present in primer residues and pyrotechnic low explosive devices. Metals detected include lead, barium, antimony, iron, aluminum, zinc, and magnesium. Detection times were found to be less than 10 min and visual limits of detection ranged from 0.025 to 0.4 µg of these metallic compounds. The resultant paper chip was then tested against various interferences and used to examine a number of different pyrotechnic compositions. This new device should prove useful in onsite detection of post-blast residues of pyrotechnics in the field due its portability and ease of use.

Jared A. Goldberg, Lars Bildsten, Bill Paxton

We present advances in modeling Type IIP supernovae using MESA for evolution to shock breakout coupled with STELLA for generating light and radial velocity curves. Explosion models and synthetic light curves can be used to translate observable properties of supernovae (such as the luminosity at day 50 and the duration of the plateau, as well as the observable quantity $ET$, defined as the time-weighted integrated luminosity that would have been generated if there was no ${\rm ^{56}Ni}$ in the ejecta) into families of explosions which produce the same light curve and velocities on the plateau. These predicted families of explosions provide a useful guide towards modeling observed SNe, and can constrain explosion properties when coupled with other observational or theoretical constraints. For an observed supernova with a measured ${\rm ^{56}Ni}$ mass, breaking the degeneracies within these families of explosions (ejecta mass, explosion energy, and progenitor radius) requires independent knowledge of one parameter. We expect the most common case to be a progenitor radius measurement for a nearby supernova. We show that ejecta velocities inferred from the Fe II$λ$ 5169 line measured during the majority of the plateau phase provide little additional information about explosion characteristics. Only during the initial shock cooling phase can photospheric velocity measurements potentially aid in unraveling light curve degeneracies.

Luis A. Zapata, Paul T. P. Ho, Estrella Guzman-Ccolque et al.

The explosive outflows are a newly-discovered family of molecular outflows associated with high-mass star forming regions. Such energetic events are possibly powered by the release of gravitational energy related with the formation of a (proto)stellar merger or a close stellar binary. Here, we present sensitive and high angular resolution observations (0.85$''$) archival CO(J=3-2) observations carried out with the Submillimeter Array (SMA) of the high-mass star forming region G5.89$-$0.39 that reveal the possible presence of an explosive outflow. We find six well-defined and narrow straight filament-like ejections pointing back approximately to the center of an expanding molecular and ionized shell located at the center of this region. These high velocity ($-$120 to $+$100 km s$^{-1}$) filaments follow a Hubble-like velocity law with the radial velocities increasing with the projected distance. The estimated kinematical age of the filaments is about of 1000 yrs, a value similar to the dynamical age found for the expanding ionized shell. G5.89 is the thus the third explosive outflow reported in the galaxy (together with Orion BN-KL and DR21) and argues in favor of the idea that this is a frequent phenomenon. In particular, explosive outflows, in conjunction with runaway stars, demonstrate that dynamical interactions in such groups are a very important ingredient in star formation.

Bo Li, Xiaowen Zhou

In this paper, we consider a class of generalized continuous-state branching processes obtained by Lamperti type time changes of spectrally positive Lévy processes using different rate functions. When explosion occurs to such a process, we show that the process converges to infinity in finite time asymptotically along a deterministic curve, and identify the speed of explosion for rate function in different regimes. To prove the main theorems, we also establish a new asymptotic result for scale function of spectrally positive Lévy process.

Jun-yi Wu

Methods used for the determination of barium content in pyrotechnics are mostly based on traditional chemical method, which is lengthy and cumbersome. If inductively coupled plasma emission spectrometry or atomic absorption spectrometry are used to determine the barium with high content, the sample solution must be highly diluted, and it must produce errors in measurement and call into question the reliability of the data. The method mentioned in this paper is about the determination of barium content in pyrotechnics used for fireworks and firecrackers based on energy dispersive X-ray fluorescence spectrometry by controlling matrix effects between elements. Using sample solution of pyrotechnics in specific concentrates, the barium content can be determined by the specific calibration curve established with an intensity calibration. This method can provide high accuracy and good precision in a short time with a simple process by efficiently controlling the matrix effects. It can fully meet the requirements for the determination of barium in pyrotechnics used for different kinds of fireworks and firecrackers around the world, and it has good generalization and practicability. The average recovery of the method can be 98.95%~100.79%, allowing for a difference of 0.5%. Introduction In China, fireworks and firecrackers are very important consumer recreational products in people’s everyday life since ancient times. Gorgeous colors produced by fireworks and firecrackers are even the barium ing role of foiling festal atmosphere in every grand holiday celebrations. In recent years, with the rapid development of global trade, fireworks and firecrackers are becoming more and more popular all over the world, more and more consumers are fascinatedby different kinds of patterns, pictures, and sound effects of fireworks and firecrackers. Barium element is commonly found in barium nitrate and barium carbonate as primary content used for pyrotechnics. Quantitative analysis of chemical compositions in pyrotechnics such as barium content is required under the Globally Harmonized System of Classification and Labeling of Chemicals(GHS)to be complemented in the fireworks and firecrackers industry. Meanwhile it will also provide a scientific and effective technical support to the management and supervision of safety production for the government, and improve products’ quality level by the manufacturers. It can also be utilized as a tool in providing valuable data in the judgment in some major arbitration and security incident analysis. Quantitative analysis method of the barium content reported in current literature is limited to traditional chemical analysis, such methods have the following disadvantages:(1) Long detecting period. Generally, it will take a skilled technician two whole days or so to complete the detection.(2) The operation is more complicated. It needs to go through many steps such as dissolving sample, filtration, precipitation collection, drying and weighing precipitation and ect. Comparing with traditional chemical analysis methods ,this method based on energy dispersive X-ray fluorescence spectrometry(EDXRF) has the 2017 International Conference on Materials, Energy, Civil Engineering and Computer (MATECC 2017) Copyright © (2017) Francis Academic Press , UK 1 advantages of simple operation steps, short period of detection, high accuracy and good precision. Theory Barium element is commonly found as primary content in chemical materials such as barium nitrate and barium carbonate in pyrotechnics used for fireworks and firecrackers. Statistical analysis shows that barium nitrate and barium carbonate in pyrotechnics is between 20% to 50% ,it can concludes that the barium content in pyrotechnics would be 10%~35% as mass fraction.Concept of the method: considering the weight of the sample is 2.0 g,constant volume is 1 L and the concentrations of the barium would be controlled in 0.2 g/L~0.70 g/L in sample solutions. And it can prove that when the barium content in the solution is in the range of 0.15 g/L~0.73g/L, there would be little matrix effects among elements. So we can establish a working curve which contains the barium elements with the content of 0.15 g/L~0.73 g/L to determine the barium content in the sample solution. In accordance with the relevant safety regulations, the sample was ground into powder of less than 180 micron. Then the sample powder is placed in an explosive‒proof oven at 50°C ‒55°C and dried for 4 hours, and then placed into a dryer for cooling down to room temperature. Pretreated sample is fully dissolved in 150mL nitric acid and then filtered into volumetric flask as sample solution. The sample solution can be put into the sample cup and placed in the tank of the EDXRF to measure the fluorescence intensity of the barium elements. The actual content of barium element in the sample can be calculated from the concentrations of the barium reading by the working curve. Experiment section Reagents Unless otherwise stated, all the reagents should be guaranteed reagents and pure water is secondary grade water as described in ISO 3696(1987). Nitric acid (1+1): mix nitric acid and pure water thoroughly according to the proportion of 1:1. Standard working solution of the barium nitrate: Weigh 3.0 g high purity barium nitrate powder reference materials (accuracy to 0.1 mg), and put it in a 300 ml beaker, add 150 mL pure water, heat the beaker and make the sample solution slightly boiling on an electric stove for 10 min. After the solution is cool down to the room temperature, transfer the solution into a 500 ml volumetric flask, add 10 mL nitric acid (1+1) and pure water to the scale.Then we can separately pipette the standard working solution of the nitric acid with volume 5 mL、10 mL、15 mL、20 mL、25 mL、30 mL、35 mL and 40 mL into eight 100 mL volumetric flasks which marked from N1 to N8, and add pure water to reach 100 mL in each volumetric flask, mix thoroughly for later use. Concentrations of the standard working solution in different flasks are shown in Table 1.