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1
LU, T. F., C. S. YOO, J. H. CHEN, and C. K. LAW. "Three-dimensional direct numerical simulation of a turbulent lifted hydrogen jet flame in heated coflow: a chemical explosive mode analysis." Journal of Fluid Mechanics 652 (May 19, 2010): 45–64. http://dx.doi.org/10.1017/s002211201000039x.
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A chemical explosive mode analysis (CEMA) was developed as a new diagnostic to identify flame and ignition structure in complex flows. CEMA was then used to analyse the near-field structure of the stabilization region of a turbulent lifted hydrogen–air slot jet flame in a heated air coflow computed with three-dimensional direct numerical simulation. The simulation was performed with a detailed hydrogen–air mechanism and mixture-averaged transport properties at a jet Reynolds number of 11000 with over 900 million grid points. Explosive chemical modes and their characteristic time scales, as well as the species involved, were identified from the Jacobian matrix of the chemical source terms for species and temperature. An explosion index was defined for explosive modes, indicating the contribution of species and temperature in the explosion process. Radical and thermal runaway can consequently be distinguished. CEMA of the lifted flame shows the existence of two premixed flame fronts, which are difficult to detect with conventional methods. The upstream fork preceding the two flame fronts thereby identifies the stabilization point. A Damköhler number was defined based on the time scale of the chemical explosive mode and the local instantaneous scalar dissipation rate to highlight the role of auto-ignition in affecting the stabilization points in the lifted jet flame.
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Xu, Chao, Ji-Woong Park, Chun Sang Yoo, Jacqueline H. Chen, and Tianfeng Lu. "Identification of premixed flame propagation modes using chemical explosive mode analysis." Proceedings of the Combustion Institute 37, no. 2 (2019): 2407–15. http://dx.doi.org/10.1016/j.proci.2018.07.069.
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Wu, Wantong, Ying Piao, Qing Xie, and Zhuyin Ren. "Flame Diagnostics with a Conservative Representation of Chemical Explosive Mode Analysis." AIAA Journal 57, no. 4 (April 2019): 1355–63. http://dx.doi.org/10.2514/1.j057994.
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Shan, Ruiqin, Chun Sang Yoo, Jacqueline H. Chen, and Tianfeng Lu. "Computational diagnostics for n-heptane flames with chemical explosive mode analysis." Combustion and Flame 159, no. 10 (October 2012): 3119–27. http://dx.doi.org/10.1016/j.combustflame.2012.05.012.
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Xu, Chao, Muhsin M. Ameen, Sibendu Som, Jacqueline H. Chen, Zhuyin Ren, and Tianfeng Lu. "Dynamic adaptive combustion modeling of spray flames based on chemical explosive mode analysis." Combustion and Flame 195 (September 2018): 30–39. http://dx.doi.org/10.1016/j.combustflame.2018.05.019.
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Wang, Lei, Yong Jiang, and Rong Qiu. "Chemical Explosive Mode Analysis for Local Reignition Scenarios in H2/N2 Turbulent Diffusion Flames." Energy & Fuels 31, no. 9 (September 6, 2017): 9939–49. http://dx.doi.org/10.1021/acs.energyfuels.6b03175.
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Hu, Yupeng, Jiawen Liu, Qiang Wan, Meng Zhang, and Minghai Li. "Numerical Study of PBX 9501 Explosive Combustion Process in Confined Space." Processes 11, no. 7 (July 10, 2023): 2056. http://dx.doi.org/10.3390/pr11072056.
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Explosives combustion is primarily classified into conductive and convective combustion. In situations where confinement is sufficiently strong, the instantaneous high pressure generated by convective combustion in cracks can cause rapid fragmentation of the explosive matrix, resulting in a significant increase in the combustion surface area and triggering a high-intensity reaction with potentially catastrophic consequences. Therefore, the study of convective combustion in cracks is crucial for ensuring the safety of weapons and explosives. Previous simulation studies have primarily used finite element analysis software, which has excellent performance in handling explosive detonation processes. However, its accuracy in describing gas behavior between explosives and constrained containers is limited. This study divides the combustion process of a pre-cracked explosive in a confined space into four stages based on reasonable assumptions and simplifications. We developed a simulation method that combines the Arrhenius formula with the MWSD model to model the combustion rate of the explosive. By introducing a correction coefficient, Con, to the Arrhenius formula, the formula and MWSD model control the first and third stages of explosive combustion, respectively, while smoothly transitioning during the second stage. We used this method to numerically simulate the experimental results of Shang Hailin et al. on a crack width of 50 μm. The simulation results include the temperature field and pressure field of the first three stages of explosive combustion and the pressure rise curve of the pressure measurement point at the same location, as in the experiment. The simulation results are consistent with the experimental results.
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Cifuentes, Luis, Ehsan Fooladgar, and Christophe Duwig. "Chemical Explosive Mode Analysis for a Jet-in-Hot-Coflow burner operating in MILD combustion." Fuel 232 (November 2018): 712–23. http://dx.doi.org/10.1016/j.fuel.2018.05.171.
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Luo, Zhaoyu, Chun Sang Yoo, Edward S. Richardson, Jacqueline H. Chen, Chung K. Law, and Tianfeng Lu. "Chemical explosive mode analysis for a turbulent lifted ethylene jet flame in highly-heated coflow." Combustion and Flame 159, no. 1 (January 2012): 265–74. http://dx.doi.org/10.1016/j.combustflame.2011.05.023.
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Szachogluchowicz, Ireneusz, Lucjan Sniezek, Krzysztof Grzelak, Heorhiy Sulym, Ihor Turchyn, and Iaroslav Pasternak. "The Analytical Model of Stress Zone Formation of Ti4Al4V/AA1050/AA2519 Laminate Produced by Explosive Bonding." Metals 9, no. 7 (July 12, 2019): 779. http://dx.doi.org/10.3390/met9070779.
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This paper contains an analytical description of the deformation of the upper layer AA2519/AA1050/Ti6Al4V laminate produced by an explosive bonding method. The basic parameters of the explosive welding process that influence the quality of the bonding are the detonation velocity of the explosive, the explosion energy, and the impact angle of the combined materials. The developed description uses the theory of elastodynamic character of materials deformation at the connection point due to local traction load. The presence of high pressure during joining was limited to the region where the plane surface moving with a constant subsonic velocity. An analytical description of the residual stresses distribution was also a performer. Results of analytical investigations were verified by structure examination of the bond zone. The work was supplemented by the chemical composition analysis of the base materials and a monotonic stretching test characterizing the basic mechanical properties of the produced laminate.
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An, Jiangtao, Yong Jiang, Meijuan Ye, and Rong Qiu. "One-dimensional turbulence simulations and chemical explosive mode analysis for flame suppression mechanism of hydrogen/air flames." International Journal of Hydrogen Energy 38, no. 18 (June 2013): 7528–38. http://dx.doi.org/10.1016/j.ijhydene.2013.04.032.
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Xu, Chao, Alexei Y. Poludnenko, Xinyu Zhao, Hai Wang, and Tianfeng Lu. "Structure of strongly turbulent premixed n-dodecane–air flames: Direct numerical simulations and chemical explosive mode analysis." Combustion and Flame 209 (November 2019): 27–40. http://dx.doi.org/10.1016/j.combustflame.2019.07.027.
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Jeong, Seung-Min, and Jeong-Yeol Choi. "Combined Diagnostic Analysis of Dynamic Combustion Characteristics in a Scramjet Engine." Energies 13, no. 15 (August 4, 2020): 4029. http://dx.doi.org/10.3390/en13154029.
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In this work, the dynamic combustion characteristics in a scramjet engine were investigated using three diagnostic data analysis methods: DMD (Dynamic Mode Decomposition), STFT (Short-Time Fourier Transform), and CEMA (Chemical Explosive Mode Analysis). The data for the analyses were obtained through a 2D numerical experiment using a DDES (Delayed Detached Eddy Simulation) turbulence model, the UCSD (University of California at San Diego) hydrogen/oxygen chemical reaction mechanism, and high-resolution schemes. The STFT was able to detect that oscillations above 50 kHz identified as dominant in FFT results were not the dominant frequencies in a channel-type combustor. In the analysis using DMD, it was confirmed that the critical point that induced a complete change of mixing characteristics existed between an injection pressure of 0.75 MPa and 1.0 MPa. A combined diagnostic analysis that included a CEMA was performed to investigate the dynamic combustion characteristics. The differences in the reaction steps forming the flame structure under each combustor condition were identified, and, through this, it was confirmed that the pressure distribution upstream of the combustor dominated the dynamic combustion characteristics of this scramjet engine. From these processes, it was confirmed that the combined analysis method used in this paper is an effective approach to diagnose the combustion characteristics of a supersonic combustor.
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Khalil, Ahmed T., Dimitris M. Manias, Efstathios-Al Tingas, Dimitrios C. Kyritsis, and Dimitris A. Goussis. "Algorithmic Analysis of Chemical Dynamics of the Autoignition of NH3–H2O2/Air Mixtures." Energies 12, no. 23 (November 21, 2019): 4422. http://dx.doi.org/10.3390/en12234422.
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The dynamics of a homogeneous adiabatic autoignition of an ammonia/air mixture at constant volume was studied, using the algorithmic tools of Computational Singular Perturbation. Since ammonia combustion is characterized by both unrealistically long ignition delays and elevated NO x emissions, the time frame of action of the modes that are responsible for ignition was analyzed by calculating the developing time scales throughout the process and by studying their possible relation to NO x emissions. The reactions that support or oppose the explosive time scale were identified, along with the variables that are related the most to the dynamics that drive the system to an explosion. It is shown that reaction H 2 O 2 (+M) → OH + OH (+M) is the one contributing the most to the time scale that characterizes ignition and that its reactant H 2 O 2 is the species related the most to this time scale. These findings suggested that addition of H 2 O 2 in the initial mixture will influence strongly the evolution of the process. It was shown that ignition of pure ammonia advanced as a slow thermal explosion with very limited chemical runaway. The ignition delay could be reduced by more than two orders of magnitude through H 2 O 2 addition, which causes only a minor increase in NO x emissions.
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Gorev, V. A. "Modes of Explosive Combustion during Emergency Explosions of the Gas Clouds in the Open Space." Occupational Safety in Industry, no. 8 (August 2022): 7–12. http://dx.doi.org/10.24000/0409-2961-2022-8-7-12.
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Emergency explosions of steam clouds in the open space occur in the deflagration combustion mode. Destructive force of the explosive waves is mainly determined by the rate of combustion in the steam cloud. Therefore, the issue of explosive combustion rate is the key one for predicting explosion parameters. To form the waves of destructive force, it is required that the combustion rate of the substance in the cloud increase by 30 or more times compared to laminar. The main and generally recognized mechanism of combustion intensification is turbulization of the process as a result of interaction of the gas flow field with various obstacles located in the area of the exploding cloud. In the work, the analysis focuses on the combustion processes in the obstacles with continuously changing blocking of space. Under such conditions, the combustion is not structured, it smoothly changes its characteristics, and not jerks at the locations of blocking barriers. That is, explosive combustion can be considered as a classic turbulent combustion of a homogeneous mixed mixture. The work gives preference to the analysis of works, in which the turbulent combustion rate is presented as allowing a change in the scale of turbulence. The results of these works are presented in the form of functions ff(U¢/Sl, l/d) of the ratio of the pulsation component of turbulence to the laminar combustion rate, and the ratio of the integral scale of turbulence to the thickness of the laminar flame. The work gives a comparison of the turbulent combustion velocity depending on the U¢/SL ratio for three values l/d = 100, 1000, 10 000. On the basis of the turbulent combustion modes diagram, the zones of applicability of various methods for determining the turbulent combustion rate are shown. The paper expresses preference for the Peters theory as the most universal and giving a realistic value of the turbulent combustion rate at l/d >> 1.
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Li, Shun Ping, Shun Shan Feng, Yong Xiang Dong, and Yun Chen. "Research on the Relationship between the Impact Explosive Temperature and Mass Ratio of PTFE/Al Reactive Material." Advanced Materials Research 591-593 (November 2012): 1017–20. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.1017.
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The impact explosive temperature of reactive material is not only an important indicator to measure the ability of explosive reaction, but also a required parameter to carry out thermo-chemical calculation. So there is important practical significance to study the impact explosive temperature effect of reactive material. Based on one-dimensional shock wave, thermodynamics and physical chemistry theory, mathematical analysis model of impact explosive temperature vs. mass ratio of the reactive material is established. By MATLAB programming, the curve of impact explosive temperature vs. the mass ratio of PTFE/Al reactive material is received, which can be used to analyze variations. Fitting function equations is obtained by MATLAB CFTOOL. At last, the contrast of original calculation curve with fitting curve validates the appropriateness of the fitting function equations. From the view of impact explosive temperature effect, we suggest that the established model and research method can be applied to the dynamic properties research of other reactive material.
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Shashin, A., R. Sheps, A. Seminenko, and V. Minko. "LOCAL EXHAUST VENTILATION WITH EJECTION OF EXPLOSIVE SUBSTANCES AND RECIRCULATION OF PURIFIED AIR." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 6, no. 2 (March 5, 2021): 28–37. http://dx.doi.org/10.34031/2071-7318-2021-6-2-28-37.
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Exhaust ventilation systems in industrial enterprises and facilities with the use of harmful substances largely determine the air exchange in the workplace to ensure normalized sanitary and hygienic conditions and operating costs. Local exhaust ventilation of explosive harmful substances is of particular importance for effective air exchange in such rooms, since their localization, suction and transportation are subject to increased requirements. The paper presents the results of analytical and experimental studies of the operation mode of a complex local exhaust device with a gas ejector for extraction explosive harmful chemicals from shelters, ensuring their effective localization, purification and recirculation of air. The boundary conditions and assumptions for calculating the characteristics of the processes of gas flow ejection, purification of technological emissions and recirculation of the purified gas flow, determined on the basis of the analysis of previously performed studies and experimental work, are given. The conditions of rational ratios device settings of extraction of emissions sources of substances that parameters of the ejector and cleaning device emission, which is achieved economic and environmental efficiency of the installation and excludes the volatile situation on the threat of chemical enterprises and objects.
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Wang, Lei, Yong Jiang, Longwei Pan, Yu Xia, and Rong Qiu. "Lagrangian investigation and chemical explosive mode analysis of extinction and re-ignition in H2/CO/N2 syngas non-premixed flame." International Journal of Hydrogen Energy 41, no. 8 (March 2016): 4820–30. http://dx.doi.org/10.1016/j.ijhydene.2016.01.043.
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Wang, Kan, Yang Liu, Hao Wang, Xiaolei Liu, Yu Jiao, and Yujian Wu. "Dynamic Process and Damage Evaluation Subject to Explosion Consequences Resulting from a LPG Tank Trailer Accident." Processes 11, no. 5 (May 16, 2023): 1514. http://dx.doi.org/10.3390/pr11051514.
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The involvement of liquefied petroleum gas (LPG), which is highly combustible and explosive, greatly increases risk in road transport. A 3D numerical model was conducted in FLACS, which depicts the dynamic process and variation of combined effects along the multi-directions of LPG explosion under an actual case. With the simulation of scenarios, power-law explosion and fireball models were used to reproduce the results, and the dynamic evolution of specific parameters during the LPG explosion process was analyzed. The results reveal that the LPG explosion’s expansion around the expressway moved along the spaces between obstacles, while conditions at the site of the accident had an enhancement effect on LPG/air mixture accumulation. The propagation trajectory of the shock wave in the horizontal direction presented a regular circle within 623.73 ms, and the overpressure was enough to lead to extensive damage to surrounding structures. Further, shock wave-driven overpressure brought hazards to buildings further afield with multiple peak values. The influence of the LPG explosive fireball evolution is significantly reflected in the injury range of the heat flux; the maximum diameter of the on-site fireball eventually extended to 148.19 m. In addition, the physical effect indicated that the turbulence intensity induced by the surrounding buildings in the accident site significantly promoted the interaction between the shock wave and flame propagation. This research proposes a detailed analysis of damage coupling characteristics caused by an LPG tank trailer explosion integrated with a FLACS-mirrored model, which are useful for blast-resistant design and disposal planning under similar accidental circumstances.
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Fedorenko, Gennadiy, Herman Fesenko, Vyacheslav Kharchenko, Ihor Kliushnikov, and Ihor Tolkunov. "Robotic-biological systems for detection and identification of explosive ordnance: concept, general structure, and models." Radioelectronic and Computer Systems, no. 2 (May 25, 2023): 143–59. http://dx.doi.org/10.32620/reks.2023.2.12.
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The subject of this study is systems for detection and identification (D&I) of explosive ordnance (EO). The aim of this study is to develop a concept, general structure, and models of a robotic-biological system for D&I of EO (RBS-D&I). The objectives are as follows: 1) to classify mobile systems for D&I of EO and suggest a concept of RBS-D&I; 2) to develop the general structure of RBS-D&I consisting of robotic (flying and ground) and biological subsystems; 3) to develop models of RBS-D&I including automaton, hierarchical, and operational ones; 4) to describe tasks and planned results of the article-related scientific project; and 5) to discuss research results. The following results were obtained. 1) The general structure of the RBS-D&I. The structure comprises the following levels: control and processing centres (mobile ground control and processing centre (MGCPC) and virtual control and processing centre); forces for detection and identification (fleet of unmanned aerial vehicles (FoU), biological detection information subsystem (BDIS), and robotic detection information subsystem (RDIS)); interference; natural covers and a bedding surface; and target objects (all munitions containing explosives, nuclear fission or fusion materials and biological and chemical agents). 2) A concept of RBS-D&I. The concept is based on RBS-D&I description, analysis, development, and operation as an integrated complex cyber-physical and cyber-biological system running in changing physical and information environments. 3) The RBS-D&I automata model. The model describes RBS-D&I operating in two modes. In mode 1, FoU and BDIS operate separately and interact through the MGCPC only. In mode 2, depending on the specifics of the tasks performed, FoU and RDIS can directly interact among themselves or through the MGCPC. 4) hierarchical model. The model has two sets of vertices: EO detection and platforms equipped with the necessary sensors. 5) An operational cycle model. The model describes land release operations via a methodology of functional modeling and graphic description of IDEF0 processes. Conclusions. The proposed concept and RBS-D&I solutions can provide high-performance and guaranteed EO detection in designated areas by the implementation of an intelligent platform and tools for planning the use of multifunctional fleets of UAVs and other RBS-D&I subsystems.
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Kelasyev, N. G., K. V. Avdeev, D. I. Levin, M. V. Lisanov, and V. V. Bobrov. "Models of Concrete and Reinforcement under Explosive Loads." Occupational Safety in Industry, no. 3 (March 2023): 14–21. http://dx.doi.org/10.24000/0409-2961-2023-3-14-21.
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In this article, the mathematical models of structural materials describing their dynamic properties are considered for calculating building structures for the action of dynamic loads. Physical and mechanical properties are described related to reinforcing steel and concrete under the action of explosive loads, as well as the influence of the loading rate and other factors on the deformation diagram of steel and concrete. The analysis is carried out concerning the reasons for the increase in the resistance of concrete and reinforcement under rapidly increasing loads. The relevance of the topic is determined by its compliance with the main goals and objectives of the Russian state policy in the field of improving the safety of buildings and structures when exposed to explosive loads. The article describes the methods of mathematical description of the structural materials behavior under the action of explosive loads. A simplified method for modeling the dynamic properties of reinforcing steel and concrete by multiplying the calculated resistance by the dynamic strengthening factor, as well as a more time-consuming method based on the equations of gas-hydrodynamics and implemented in the LS-DYNA software package, are considered. The authors used the method of taking into account the dynamic strengthening of reinforcing steel and concrete based on the nonlinear behavior of materials using diagrams with a piecewise linear description. Dynamic hardening was considered using hardening factors. The purpose of the study is to compare the results of numerical calculation according to the method proposed by the authors with the data obtained during the experimental program Blind Blast Test. The calculation was carried out by the finite element method using the Lira 10.12 calculation complex. The DYNAMICS+ system was used to simulate the load from the action of an external explosion. The experimental model is a reinforced concrete slab reinforced with ASTM Grade 60#3 rods. The results of numerical calculation showed high convergence with the experimental program. The use of the method of accounting for the dynamic hardening of reinforcing steel and concrete, based on the nonlinear behavior of materials using diagrams with a piecewise linear description, is the most optimal model that allows to get a fairly accurate solution and at the same time is acceptable from the point of view of labor intensity. This article is of interest to design engineers engaged in the calculation of structures for explosive loads.
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Zhou, Dezhi, Hongyuan Zhang, and Suo Yang. "A Robust Reacting Flow Solver with Computational Diagnostics Based on OpenFOAM and Cantera." Aerospace 9, no. 2 (February 14, 2022): 102. http://dx.doi.org/10.3390/aerospace9020102.
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In this study, we developed a new reacting flow solver based on OpenFOAM (OF) and Cantera, with the capabilities of (i) dealing with detailed species transport and chemistry, (ii) integration using a well-balanced splitting scheme, and (iii) two advanced computational diagnostic methods. First of all, a flaw of the original OF chemistry model to deal with pressure-dependent reactions is fixed. This solver then couples Cantera with OF so that the robust chemistry reader, chemical reaction rate calculations, ordinary differential equations (ODEs) solver, and species transport properties handled by Cantera can be accessed by OF. In this way, two transport models (mixture-averaged and constant Lewis number models) are implemented in the coupled solver. Finally, both the Strang splitting scheme and a well-balanced splitting scheme are implemented in this solver. The newly added features are then assessed and validated via a series of auto-ignition tests, a perfectly stirred reactor, a 1D unstretched laminar premixed flame, a 2D counter-flow laminar diffusion flame, and a 3D turbulent partially premixed flame (Sandia Flame D). It is shown that the well-balanced property is crucial for splitting schemes to accurately capture the ignition and extinction events. To facilitate the understanding on combustion modes and complex chemistry in large scale simulations, two computational diagnostic methods (conservative chemical explosive mode analysis, CCEMA, and global pathway analysis, GPA) are subsequently implemented in the current framework and used to study Sandia Flame D for the first time. It is shown that these two diagnostic methods can extract the flame structure, combustion modes, and controlling global reaction pathways from the simulation data.
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Dodoulas, Ilias A., and Salvador Navarro-Martinez. "Analysis of extinction in a non-premixed turbulent flame using large eddy simulation and the chemical explosion mode analysis." Combustion Theory and Modelling 19, no. 1 (January 2, 2015): 107–29. http://dx.doi.org/10.1080/13647830.2014.993713.
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Kharlamov, Yu A., L. G. Polonsky, N. O. Balytska, and S. A. Klymenko. "Innovative Potential of Gas Detonation." Nauka ta innovacii 16, no. 6 (June 12, 2020): 105–12. http://dx.doi.org/10.15407/scin16.06.105.
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Introduction. Explosive technologies are widely used in the extraction industries, in mechanical engineering for welding, hardening, etc. However, the use of solid explosives is limited, above all, by safety requirements. Therefore, the use of a safer and more convenient source of energy, gas detonation, is attracting much attention. Pressures, temperatures, and velocities in detonation waves or shock waves in gases close to them in terms of intensity, as well as the pulse nature of the influence of these factors determine a high potential of their technical and technological use. Problem Statement. In many technical systems, deflagration modes of burning prevail. However, a more thermodynamically advantageous method of combustion and conversion of chemical energy of fuel into useful work is the detonation mode of combustion. This ensures the feasibility of development, research and wider implementation of various technologies and devices using controlled gas detonation. Purpose. Systematization and analysis of the main trends in the development and design of detonation gas technologies and devices in Ukraine and throughout the world. Materials and Methods. Systematization and analysis of scholarly research publications and patents on the practical application of gas detonation in various sectors of the economy. Results. The tendencies of practical use of gas detonation in different branches of industry have been revealed and analyzed. Priority developments in the technological application of the method in mechanical engineering have been performed in Ukraine. However, in many technical areas Ukraine has fallen behind the world leaders in terms of the creation of detonation gas technologies and devices. Conclusions. For the practical use of the potential of gas detonation, it is necessary to develop fundamentally new devices that ensure reliable, safe, and controlable generation and propagation of detonation waves in gases and sprayed fuels. Gas detonation is promising for the creation of more advanced technologies and equipment.
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Kharlamov, Yu A., L. G. Polonsky, N. O. Balytska, and S. A. Klymenko. "Innovative Potential of Gas Detonation." Science and innovation 16, no. 6 (November 2020): 104–10. http://dx.doi.org/10.15407/scine16.06.104.
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Introduction. Explosive technologies are widely used in the extraction industries, in mechanical engineering for welding, hardening, etc. However, the use of solid explosives is limited, above all, by safety requirements. Therefore, the use of a safer and more convenient source of energy, gas detonation, is attracting much attention. Pressures, temperatures, and velocities in detonation waves or shock waves in gases close to them in terms of intensity, as well as the pulse nature of the influence of these factors determine a high potential of their technical and technological use. Problem Statement. In many technical systems, deflagration modes of burning prevail. However, a more thermodynamically advantageous method of combustion and conversion of chemical energy of fuel into useful work is the detonation mode of combustion. This ensures the feasibility of development, research and wider implementation of various technologies and devices using controlled gas detonation. Purpose. Systematization and analysis of the main trends in the development and design of detonation gas technologies and devices in Ukraine and throughout the world. Materials and Methods. Systematization and analysis of scholarly research publications and patents on the practical application of gas detonation in various sectors of the economy. Results. The tendencies of practical use of gas detonation in different branches of industry have been revealed and analyzed. Priority developments in the technological application of the method in mechanical engineering have been performed in Ukraine. However, in many technical areas Ukraine has fallen behind the world leaders in terms of the creation of detonation gas technologies and devices. Conclusions. For the practical use of the potential of gas detonation, it is necessary to develop fundamentally new devices that ensure reliable, safe, and controlable generation and propagation of detonation waves in gases and sprayed fuels. Gas detonation is promising for the creation of more advanced technologies and equipment.
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Skob, Yurii, Yuriy Dreval, Alexey Vasilchenko, and Roman Maiboroda. "Selection of Material and Thickness of the Protective Wall in the Conditions of a Hydrogen Explosion of Various Power." Key Engineering Materials 952 (August 18, 2023): 121–29. http://dx.doi.org/10.4028/p-st1vet.
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The main purpose of this study is a numerical assessment of the consequences of an explosion of a hydrogen-air cloud on the personnel of a hydrogen fueling station and the strength of a protective solid wall of certain dimensions. An explosive gas mixture is formed as a result of the destruction of high-pressure cylinders, the number of which determines the size of the cloud, the power of the explosion, and the scale of the consequences of environmental impact. To obtain the spatio-temporal distribution of the maximum overpressure and the impulse of the shock wave compression phase, a mathematical model of the dispersion of an active gaseous admixture is used, taking into account the chemical interaction with air oxygen. The probable consequences of the shock-impulse impact on the personnel at the control point are carried out using probit analysis. The values of the maximum bending moment and stress at the base of the protective wall, which result from the impact of the blast wave, are used to deterministically estimate the minimum wall thickness necessary for the safe operation of the protective device. The mathematical model takes into account the complex terrain and the three-dimensional non-stationary nature of the shock wave propagation process, and it is a source of data necessary to solve the problem of the strength of solid objects located in the area of baric perturbation of the gaseous medium. The developed methodology makes it possible to carry out a comparative analysis of the effectiveness of protective structures in relation to the power of the explosion.
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Krokhalev, A. V., V. O. Kharlamov, D. R. Chernikov, S. V. Kuz’min, and V. I. Lysak. "Using explosion loading to obtain coatings of chromium carbide and titanium mixtures in deposition mode." Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya, no. 2 (June 16, 2022): 70–78. http://dx.doi.org/10.17073/1997-308x-2022-2-70-78.
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The paper presents the results of studies into the microstructure, chemical and phase composition of coatings deposited on a steel substrate using the sliding explosive loading of Cr3C2 chromium carbide and titanium powder mixtures. The equilibrium phase composition of coatings was calculated by computational thermodynamic modeling using the Thermo-Calc software package. The structure and elemental composition were studied using a FEI Versa 3D scanning electron microscope with an integrated EDAX Apollo X system for energy dispersive X-ray microprobe analysis. A Bruker D8 Advance diffractometer was used for X-ray phase analysis. It was shown that when the powder layer is loaded by a sliding detonation wave, it can be shifted along the substrate surface due to the horizontal mass velocity component of compacted material particles. This shift causes the inner layer of the compacted powder and the surface layer of the substrate to melt as a result of friction. The presence of a liquid phase prevents the compacted powder layer deceleration so that the major part of it is removed from the substrate surface. The liquid phase remaining on the surface undergoes rapid quenching due to heat removal into the substrate and forms a deposited coating containing both the components of the initial powder mixture and the components of the substrate to be coated. It was established that the deposited layer structure features by extremely high dispersion (grain size does not exceed 250 nm), and its phase composition turns out to be close to a thermodynamically equilibrium one. When using powder mixtures of chromium carbide with 40% titanium, a coating is formed consisting of titanium carbide with a metal binder based on solid solutions of iron and titanium in chromium.
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Eades, Robert, and Kyle Perry. "Evaluation of a 38 L Explosive Chamber for Testing Coal Dust Explosibility." Journal of Combustion 2019 (September 2, 2019): 1–7. http://dx.doi.org/10.1155/2019/5810173.
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Coal dust explosions are the deadliest disasters facing the coal mining industry. Research has been conducted globally on this topic for decades. The first explosibility tests in the United States were performed by the Bureau of Mines using a 20 L chamber. This serves as the basis for all standardized tests used for combustible dusts. The purpose of this paper is to investigate the use of a new 38 L chamber for testing coal dust explosions. The 38 L chamber features design modifications to model the unique conditions present in an underground coal mine when compared to other industries where combustible dust hazards are present. A series of explosibility tests were conducted within the explosive chamber using a sample of Pittsburgh pulverized coal dust and a five kJ Sobbe igniter. Analysis to find the maximum pressure ratio and Kst combustible dust parameter was performed for each trial. Based upon this analysis, observations are made for each concentration regarding whether the explosibility test was under-fueled or over-fueled. Based upon this analysis, a recommendation for future explosibility testing concentrations is made.
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Kulikov, Yevgeny, Gennady Kulikov, Vladimir Apse, Anatoly Shmelev, and Nikolay Geraskin. "Computational model and physical and technical factors determining the plutonium proliferation resistance." Nuclear Energy and Technology 4, no. 2 (November 26, 2018): 93–97. http://dx.doi.org/10.3897/nucet.4.30525.
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Since the closed nuclear fuel cycle suggests that plutonium is extracted from irradiated fuel and is recycled in nuclear reactors as part of the loaded fuel, proliferation resistance of fissile materials (plutonium) is becoming a problem of a practical significance. It is important to understand to what extent the physical and technical properties of fissile materials are capable to prevent these from being diverted to nonenergy uses. This paper considers the term ”proliferation resistance” from a physical and technical point of view with no measures taken for the physical protection, accounting and control of nuclear materials. Thus, proliferation resistance of plutonium means that it is technically impossible to fabricate a nuclear explosive device (NED) of the implosion type due to the overheating of the device’s components and the resultant NED failure. The following conclusions have been made. The assessment of the plutonium proliferation resistance is not justified where it relies on the analysis of an implosion-type NED excluding the use of modern heat-resistant and heat-conducting chemical explosives (CE) which are inaccessible. Consideration of the asymptotic temperature profile in the NED components is not justified enough for the development of plutonium proliferation resistance recommendations. No options enabling the slowdown of the NED warm-up process have been exhausted for analyzing the physical and technical factors that determine the proliferation resistance of plutonium. The assessment of the plutonium proliferation resistance is not justified where it relies on the analysis of an implosion-type NED excluding the use of modern heat-resistant and heat-conducting chemical explosives (CE) which are inaccessible. Consideration of the asymptotic temperature profile in the NED components is not justified enough for the development of plutonium proliferation resistance recommendations. No options enabling the slowdown of the NED warm-up process have been exhausted for analyzing the physical and technical factors that determine the proliferation resistance of plutonium. General conclusion. The underlying rationale in a fundamental monograph by Dr. G. Kessler proved to be insufficiently valid, which has led to an unfounded inference as to the status of the plutonium proliferation resistance. The development of the procedures used and other factors taken into account are expected to increase the requirements to the content of the 238Pu isotope in plutonium for ensuring its proliferation resistance.
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Wu, Yao-Chang, Bin Laiwang, and Chi-Min Shu. "Investigation of an Explosion at a Styrene Plant with Alkylation Reactor Feed Furnace." Applied Sciences 9, no. 3 (February 1, 2019): 503. http://dx.doi.org/10.3390/app9030503.
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To prevent and mitigate chemical risks in the petrochemical industry, such as fires and spillage, process safety management (PSM), is essential, especially where flammable, corrosive, explosive, toxic, or otherwise dangerous chemicals are used. We investigated process safety (PS) between man–machine (material equipment) and environmental interfaces by using process hazard analysis (PHA) and fault tree analysis (FTA). By analyzing the data obtained through machinery and mechanical integrity (MI), pre-startup safety review (PSSR), current operating modes, and areal locations of hazardous atmospheres (ALOHA) simulations of the disaster’s aftermath, the cause of the styrene plant accident was found to be the fuel furnace (F101) switching process. Although the furnace had been extinguished, fuel continued to enter the furnace, and it was exposed to a high-temperature surface, resulting in the flashing ignition of the C4 fuel. The plan-do-check-act (PDCA) management model can be used to forestall the system from accident, and it is used to improve the proposal and develop countermeasures that would increase PSM performance and substantially lessen the impact of the thermal hazard. Disasters are often attributable to the unsafe state of machinery, equipment, or the environment, dangerous behaviors of the operator, and the lack of a thorough management system. It is anticipated that the investigation and analysis of the accident would not only find the real cause of the disaster but also lead to the establishment of better effective solutions for common safety problems.
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Ratriwardhani, Ratna Ayu, Merry Sunaryo, Octavianus Hutapea, and Muslikha Nourma Rhomadhoni. "Application of failure mode effect analysis on hazard identification and risk control." Bali Medical Journal 11, no. 2 (August 17, 2022): 892–96. http://dx.doi.org/10.15562/bmj.v11i2.3146.
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Introduction: PT. X is a chemical industry with high hazards, especially those related to hazardous and toxic materials; the company also uses equipment and machines with fire or explosion hazards. Component's failure to operate is a major problem in PT. X. The specific objective of this study was to evaluate hazards and control the risks to prevent accidents and protect company assets, especially for employee safety. Methods: The data collected is Process Flow Diagram (PFD), Material Safety Data Sheet (MSDS), and component failure data. The risk assessment for the components of Sodium Silicate Production is carried out by multiplying the occurrence measurement scale and severity measurement scale. The risk value for the unacceptable risk category is between 12 and 25, where the risk must be controlled first. Results: This study found that the highest risk value is dissolver tank leaks, the production pump not working, and the ball valve stuck. An example of structural mitigation in the dissolver tank is to carry out routine maintenance once a month to know the material's condition and to immediately make repairs if there are signs of tank damage to prevent leakage in the tank. Conclusions: This research proves that some hazards have not been evaluated and controlled, so there are still some failures in the production process of Sodium Silicate.
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HART, PETER W., CARL HOUTMAN, and KOLBY HIRTH. "Hydrogen peroxide and caustic soda: Dancing with a dragon while bleaching." TAPPI Journal 12, no. 7 (August 1, 2013): 59–65. http://dx.doi.org/10.32964/tj12.7.59.
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When hydrogen peroxide is mixed with caustic soda, an auto-accelerating reaction can lead to generation of significant amounts of heat and oxygen. On the basis of experiments using typical pulp mill process concentration and temperatures, a relatively simple kinetic model has been developed. Evaluation of these model results reveals that hydrogen peroxide-caustic soda systems are extremely sensitive to hydrogen peroxide:caustic soda ratio, transition metal contamination, and temperature. Small changes in initial conditions can result in a closed system becoming explosive. Analysis of model results was used to develop guidelines for safer application of hydrogen peroxide in a mill setting.
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Dvořák, Richard, Zdeněk Chobola, Iveta Plšková, Rudolf Hela, and Lenka Bodnárová. "Classification of Thermally Degraded Concrete by Acoustic Resonance Method and Image Analysis via Machine Learning." Materials 16, no. 3 (January 22, 2023): 1010. http://dx.doi.org/10.3390/ma16031010.
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The study of the resistance of plain concrete to high temperatures is a current topic across the field of civil engineering diagnostics. It is a type of damage that affects all components in a complex way, and there are many ways to describe and diagnose this degradation process and the resulting condition of the concrete. With regard to resistance to high temperatures, phenomena such as explosive spalling or partial creep of the material may occur. The resulting condition of thermally degraded concrete can be assessed by a number of destructive and nondestructive methods based on either physical or chemical principles. The aim of this paper is to present a comparison of nondestructive testing of selected concrete mixtures and the subsequent classification of the condition after thermal degradation. In this sense, a classification model based on supervised machine learning principles is proposed, in which the thermal degradation of the selected test specimens are known classes. The whole test set was divided into five mixtures, each with seven temperature classes in 200 °C steps from 200 °C up to 1200 °C. The output of the paper is a comparison of the different settings of the classification model and validation algorithm in relation to the observed parameters and the resulting model accuracy. The classification is done by using parameters obtained by the acoustic NDT Impact-Echo method and image-processing tools.
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Mai, Viet-Chinh, Xuan-Bach Luu, Cong-Binh Dao, and Dinh-Viet Le. "Investigate the Structural Response of Ultra High Performance Concrete Column under the High Explosion." Defence Science Journal 71, no. 2 (March 10, 2021): 256–64. http://dx.doi.org/10.14429/dsj.71.16427.
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Most of the structures that are damaged by an explosion are not initially designed to resist this kind of load. In the overall structure of any building, columns play an important role to prevent the collapse of frame structure under blast impact. Hence, the main concept in the blast resistance design of the structure is to improve the blast load capacity of the column. In this study, dynamic analysis and numerical model of Ultra High Performance Concrete (UHPC) column under high explosive load, is presented. Based on the Johnson Holmquist 2 damage model and the subroutine in the ABAQUS platform, a total of twenty UHPC model of the column were calculated. The objective of the article is to investigate the structural response of the UHPC column and locate the most vulnerable scenarios to propose necessary recommendations for the UHPC column in the blast loading resistance design. The input parameters, including the effect of various shapes of cross-section, scaled distance, steel reinforcement ratio, and cross-section area, are analyzed to clarify the dynamic behavior of the UHPC column subjected to blast loading. Details of the numerical data, and the discussion on the important obtained results, are also provided in this paper.
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Mishra, Romil, Arvind Kumar Mishra, and Bhanwar Singh Choudhary. "High-Speed Motion Analysis-Based Machine Learning Models for Prediction and Simulation of Flyrock in Surface Mines." Applied Sciences 13, no. 17 (September 1, 2023): 9906. http://dx.doi.org/10.3390/app13179906.
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Blasting is a cost-efficient and effective technique that utilizes explosive chemical energy to generate the necessary pressure for rock fragmentation in surface mines. However, a significant portion of this energy is dissipated in undesirable outcomes such as flyrock, ground vibration, back-break, etc. Among these, flyrock poses the gravest threat to structures, humans, and equipment. Consequently, the precise estimation of flyrock has garnered substantial attention as a prominent research domain. This research introduces an innovative approach for demarcating the hazardous zone for bench blasting through simulation of flyrock trajectories with probable launch conditions. To accomplish this, production blasts at five distinct surface mines in India were monitored using a high-speed video camera and data related to blast design and flyrock launch circumstances including the launch velocity (vf) were gathered by conducting motion analysis. The dataset was then used to develop ten Bayesian optimized machine learning regression models for predicting vf. Among all the models, the Extremely Randomized Trees Regression model (ERTR-BO) demonstrated the best predictive accuracy. Moreover, Shapely Additive Explanation (SHAP) analysis of the ERTR-BO model unveiled bulk density as the most influential input feature in predicting vf, followed by other features. To apply the model in a real-world setting, a user interface was developed to aid in flyrock trajectory simulation during bench blast designing.
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Gabhane, Lalit Rajaramji, and NagamalleswaraRao Kanidarapu. "Environmental Risk Assessment Using Neural Network in Liquefied Petroleum Gas Terminal." Toxics 11, no. 4 (April 7, 2023): 348. http://dx.doi.org/10.3390/toxics11040348.
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The accidental release of toxic gases leads to fire, explosion, and acute toxicity, and may result in severe problems for people and the environment. The risk analysis of hazardous chemicals using consequence modelling is essential to improve the process reliability and safety of the liquefied petroleum gas (LPG) terminal. The previous researchers focused on single-mode failure for risk assessment. No study exists on LPG plant multimode risk analysis and threat zone prediction using machine learning. This study aims to evaluate the fire and explosion hazard potential of one of Asia’s biggest LPG terminals in India. Areal locations of hazardous atmospheres (ALOHA) software simulations are used to generate threat zones for the worst scenarios. The same dataset is used to develop the artificial neural network (ANN) prediction model. The threats of flammable vapour cloud, thermal radiations from fire, and overpressure blast waves are estimated in two different weather conditions. A total of 14 LPG leak scenarios involving a 19 kg capacity cylinder, 21 tons capacity tank truck, 600 tons capacity mounded bullet, and 1350 tons capacity Horton sphere in the terminal are considered. Amongst all scenarios, the catastrophic rupture of the Horton sphere of 1350 MT capacity presented the most significant risk to life safety. Thermal flux of 37.5 kW/ m2 from flames will damage nearby structures and equipment and spread fire by the domino effect. A novel soft computing technique called a threat and risk analysis-based ANN model has been developed to predict threat zone distances for LPG leaks. Based on the significance of incidents in the LPG terminal, 160 attributes were collected for the ANN modelling. The developed ANN model predicted the threat zone distance with an accuracy of R2 value being 0.9958, and MSE being 202.9061 in testing. These results are evident in the reliability of the proposed framework for safety distance prediction. The LPG plant authorities can adopt this model to assess the safety distance from the hazardous chemical explosion based on the prior forecasted atmosphere conditions from the weather department.
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Voitenko, Yu, Viktoria Vapnichna, and O. Voitenko. "ON THE DESTRUCTION AND PREFRACTURING OF SOLID ROCKS UNDER BLASTING IN FORMATION CONDITIONS." Geoengineering, no. 7 (December 5, 2022): 7–16. http://dx.doi.org/10.20535/2707-2096.7.2022.267555.
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Purpose and task. Analysis and specification of mechanisms of softening and change of structure of monolithic and low-fractured rocks under blasting of single and dispersed charges, definition of the reasons and model of their evolution in a formation. To solve this goal, the followingscientific tasks were set in the work:1. Estimation of force factors of external action on rock.2. Thermodynamic analysis and detection of mechanisms of structural changes in rocks at a considerable distance from the well, which provide a change in its productivity.Research methods. To solve the set tasks, the following were performed: calculations of the attenuation of shock wave amplitudes generated during the explosion of spherical and elongated charges; analysis of the results of explosive treatments of oil and gas wells; energy analysis of processes and mechanisms of changes that occur around the well in the reservoir.The main results. Studies have shown that structural changes in rocks during low-energy explosions, as well as other low-energy methods of external action on the reservoir occur in the form of increased cracking of rocks at micro and macro levels due to cooperative effects of external action, internal reservoir energy and physico-chemical effects of reservoir fluids.The main results. The mechanisms of decompaction of the rocks in rock formation conditions in the presence of rock and reservoir pressure at low-energy external actions are considered. Experiments on the operation of oil, oil and gas and gas wells show that the transition of the system "well - formation" from one thermodynamic state to another occurs in a time that depends on the internal energy of the formation. The transition is the result of the cooperative effects of the combined action of external influences, the internal energy of the formation and rock pressure. For gas wells this time does not exceed a few hours or days, for oil and oil and gas with depths of 3000… 4000 m the typical time of the well to reach maximum productivity is ≈ (30 - 90) days.Conclusions and practical significance. The analysis of the results of industrial tests of explosive intensification technology and calculations of attenuation of compression wave amplitudes show that under rock pressure conditions structural changes in rock after explosions of several charges occur at distances up to ≈ (80… 100) R0. Under reservoir conditions, the main reasons for the appearance of such long zones of increased permeability around the well are the cooperativeeffects of the combined action of blast waves, reservoir gases (methane, carbon dioxide, helium and possibly hydrogen), as well as changes in rock pressure in the process of its development. Of practical importance is to understand the sequence of technological operations in the work tointensify the inflow of oil and gas.
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Ohol, Rajesh B., B. A. Parate, and Dineshsingh Thakur. "Plastic Deformation of High Explosive Projectile 155 mm during Gun Launch Conditions using Finite Element Method." Defence Science Journal 72, no. 6 (December 6, 2022): 793–800. http://dx.doi.org/10.14429/dsj.72.18197.
Full textAbstract:
The structural integrity of artillery projectile 155mm high explosive Extended Range Full Bore (ERFB)boat tail designed for 155mm howitzer guns of 39, 45 and 52 calibre plays a key role inside the gun barrel. Thisprojectile comprises a shell body, a driving band, a boat tail, nubs, an explosive, and a fuze. Plastic deformationof the projectile and stripping of driving band are not permitted, when projectile is fired. An investigational study is necessitated to check the plastic deformation of the projectile subjected to maximum propellant charge pressure.The aim of this study is to check the effective plastic deformation and affirm the structural integrity. A 3-D explicit dynamic structural analysis of 155 mm HE ERFB BT during gun launch conditions is carried out by finite element method using FE code ABAQUS/Explicit. To understand the non-linear mechanical behavior of the projectile, the true stress-strain curves of the materials are considered. The plastic behavior of the projectile subjected to the time-dependent loading is studied by using the von Mises plasticity model. The results reveal that the shell body and boat tail have no plastic deformation and the most stressed component is the driving band. The investigation has affirmed the structural integrity of the projectile during gun launch conditions.
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McDonald, Kenneth, Derek Sanchez, Kenneth Voet, Ryan Powis, Joshua Norris, and Rob Prins. "Developing Fuzzy Cognitive Mapping Techniques for Consequence Analysis of Second and Third Order Effects." Industrial and Systems Engineering Review 3, no. 2 (July 16, 2015): 71–81. http://dx.doi.org/10.37266/iser.2015v3i2.pp71-81.
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The Defense Threat Reduction Agency (DTRA) is the Department of Defense’s (DOD) official Combat Support Agency for countering weapons of mass destruction (WMD). DTRA focuses on WMD and mitigating the consequences of a chemical, biological, radiological, nuclear and high yield explosive threat (CBRNE). The initial direct effects of a CBRNE incident are well defined and documented; however, the second and third order effect’s are complex and not thoroughly understood or documented. Consequence analysis is the practice of analyzing the effects of major events such as a CBRNE event and can assist in predicting the second and third order effects. Currently there is no method to predict or analyze the second and third order effects of CBRNE events. This research focused on identifying the entities associated with a CBRNE event initially. The use of experts and surveys developed an exhaustive list of entities and associated realtionships. The follow-on research focused on the type and strength of the entity relationships. Next, Fuzzy Cognitive Mapping (FCM) techniques identify and evaluate the complex relationships of the second and third order effects. Using a mind mapping computer program, FCM techniques produced second and third order effect relationships. The final product provided a solid first attempt at analyzing a CBRNE event and the associated second and third order effects. Subsequent research will require greater effort to employ system dynamics techniques to enhance the product and develop a more thorough model.
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Xia, Zhiyu, Zhengyi Xu, Dan Li, and Jianming Wei. "A Novel Method for Source Tracking of Chemical Gas Leakage: Outlier Mutation Optimization Algorithm." Sensors 22, no. 1 (December 23, 2021): 71. http://dx.doi.org/10.3390/s22010071.
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Chemical industrial parks, which act as critical infrastructures in many cities, need to be responsive to chemical gas leakage accidents. Once a chemical gas leakage accident occurs, risks of poisoning, fire, and explosion will follow. In order to meet the primary emergency response demands in chemical gas leakage accidents, source tracking technology of chemical gas leakage has been proposed and evolved. This paper proposes a novel method, Outlier Mutation Optimization (OMO) algorithm, aimed to quickly and accurately track the source of chemical gas leakage. The OMO algorithm introduces a random walk exploration mode and, based on Swarm Intelligence (SI), increases the probability of individual mutation. Compared with other optimization algorithms, the OMO algorithm has the advantages of a wider exploration range and more convergence modes. In the algorithm test session, a series of chemical gas leakage accident application examples with random parameters are first assumed based on the Gaussian plume model; next, the qualitative experiments and analysis of the OMO algorithm are conducted, based on the application example. The test results show that the OMO algorithm with default parameters has superior comprehensive performance, including the extremely high average calculation accuracy: the optimal value, which represents the error between the final objective function value obtained by the optimization algorithm and the ideal value, reaches 2.464e-15 when the number of sensors is 16; 2.356e-13 when the number of sensors is 9; and 5.694e-23 when the number of sensors is 4. There is a satisfactory calculation time: 12.743 s/50 times when the number of sensors is 16; 10.304 s/50 times when the number of sensors is 9; and 8.644 s/50 times when the number of sensors is 4. The analysis of the OMO algorithm’s characteristic parameters proves the flexibility and robustness of this method. In addition, compared with other algorithms, the OMO algorithm can obtain an excellent leakage source tracing result in the application examples of 16, 9 and 4 sensors, and the accuracy exceeds the direct search algorithm, evolutionary algorithm, and other swarm intelligence algorithms.
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Sydorenko, Yuryi M., Bohdan Jo Semon, Vadim V. Yakovenko, Yevhen V. Ryzhov, and Eugene G. Ivanyk. "Spatial Distribution of Mass and Speed on Movement of Two Shrapnel Discs of Variable Thickness in Explosive Load." Defence Science Journal 70, no. 5 (October 8, 2020): 479–85. http://dx.doi.org/10.14429/dsj.70.14524.
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Results of studies of the explosive expansion of a set of shrapnel discs of natural crushing are described in the article. Set consisted of two disks of different thickness, but of a fixed total mass. The studies were carried out by computer simulation of shock-wave processes in a continuous formulation using the ANSYS/LS-DYNA program. The program of computer design foresees development of three-dimensional certainly-element model including, in accordance with symmetry of the examined system fourth part of the examined explosive system of casting block, with imposed on its knots of the proper scopes terms concerted with taken mixed Lagrangian-Eulerian approach within the framework of the continuum model. The effect of the order of installing disks of different thickness on the distribution of their mass and its velocity in the middle of the meridional angle of expansion is established. The analysis of the computer simulation presented on the basis of numerical studies on the distribution of the mass of the disks and its velocity of motion suggests that to create a narrow high-speed uniformly filled fragmentary mass of the axial flow, it is necessary to change the geometric shape of the disc so that in the central angular zones of the disks. This allows the velocity of the fragment mass to be aligned along the radius of the discs and to fill the first angular zones with the required mass of fragments.
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Wu, Qian, Xiao Tang, Lei Kong, Xu Dao, Miaomiao Lu, Zirui Liu, Wei Wang, et al. "Evaluation and Bias Correction of the Secondary Inorganic Aerosol Modeling over North China Plain in Autumn and Winter." Atmosphere 12, no. 5 (April 30, 2021): 578. http://dx.doi.org/10.3390/atmos12050578.
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Secondary inorganic aerosol (SIA) is the key driving factor of fine-particle explosive growth (FPEG) events, which are frequently observed in North China Plain. However, the SIA simulations remain highly uncertain over East Asia. To further investigate this issue, SIA modeling over North China Plain with the 15 km resolution Nested Air Quality Prediction Model System (NAQPMS) was performed from October 2017 to March 2018. Surface observations of SIA at 28 sites were obtained to evaluate the model, which confirmed the biases in the SIA modeling. To identify the source of these biases and reduce them, uncertainty analysis was performed by evaluating the heterogeneous chemical reactions in the model and conducting sensitivity tests on the different reactions. The results suggest that the omission of the SO2 heterogeneous chemical reaction involving anthropogenic aerosols in the model is probably the key reason for the systematic underestimation of sulfate during the winter season. The uptake coefficient of the “renoxification” reaction is a key source of uncertainty in nitrate simulations, and it is likely to be overestimated by the NAQPMS. Consideration of the SO2 heterogeneous reaction involving anthropogenic aerosols and optimization of the uptake coefficient of the “renoxification” reaction in the model suitably reproduced the temporal and spatial variations in sulfate, nitrate and ammonium over North China Plain. The biases in the simulations of sulfate, nitrate, ammonium, and particulate matter smaller than 2.5 μm (PM2.5) were reduced by 84.2%, 54.8%, 81.8%, and 80.9%, respectively. The results of this study provide a reference for the reduction in the model bias of SIA and PM2.5 and improvement of the simulation of heterogeneous chemical processes.
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Catureba, Rafaela Pedroso, Aldelio Bueno Caldeira, and Rodrigo Otávio de Castro Guedes. "Numerical Simulation of the TNT Solidification Process." Defence Science Journal 69, no. 4 (July 15, 2019): 336–41. http://dx.doi.org/10.14429/dsj.69.13536.
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The solidification phenomenon is present in the casting process of energetic materials. In defence industry, trinitrotoluene (TNT) is used as main charge for high explosive ammunitions. The present study tackles the numerical simulation of the solidification process of TNT by means of a two-dimensional transient model in cylindrical coordinates. The heat conduction problem is solved by using the enthalpy method that rewrites the governing equation in terms of this variable. The transient diffusive equation is then numerically solved by applying finite volumes in an explicit scheme. The analysis the mold thickness and the convective boundary conditions are analysed to assess how they affect heat transfer during solidification. Results obtained allow for a better comprehension of this type of problem.
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Soma, Venugopal Rao, and Abdul Kalam Shaik. "Femtosecond Filaments for Standoff Detection of Explosives." Defence Science Journal 70, no. 4 (July 13, 2020): 359–65. http://dx.doi.org/10.14429/dsj.70.14962.
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In this report, we present our results from various studies to qualitatively discriminate the common military explosives viz. RDX, TNT and HMX in their pure form at a distance of ~6.5 m in standoff mode using femtosecond (fs) filament induced breakdown spectroscopy technique (fs FIBS) together with principal component analysis. A ~30 cm length fs filament obtained by a two-lens configuration was used to interrogate those energetic molecules in the form of pressed pellets (150 mg each). The plasma emissions were collected by a Schmidt-Cassegrain telescope (SCT) from a distance of ~8 m away from the investigation zone. Additionally, a few significant results obtained from the LIBS-based investigations of nitroimidazoles with respect to the standoff distance (~2 m) are discussed. Furthermore, we have also summarised a few important results from our recent investigations of bulk energetic materials in various configurations (including those with fs filaments). The results obtained from various fs FIBS configurations corroborate that the filament generation and its properties, the size and f-number of collection optics influence signal strength in the FIBS technique. These results project the fs FIBS technique as a potential technique for investigations aimed at hazardous materials and harsh environments in the standoff mode.
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López, Luis Rafael, Mabel Mora, Caroline Van der Heyden, Juan Antonio Baeza, Eveline Volcke, and David Gabriel. "Model-Based Analysis of Feedback Control Strategies in Aerobic Biotrickling Filters for Biogas Desulfurization." Processes 9, no. 2 (January 22, 2021): 208. http://dx.doi.org/10.3390/pr9020208.
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Biotrickling filters are one of the most widely used biological technologies to perform biogas desulfurization. Their industrial application has been hampered due to the difficulty to achieve a robust and reliable operation of this bioreactor. Specifically, biotrickling filters process performance is affected mostly by fluctuations in the hydrogen sulfide (H2S) loading rate due to changes in the gas inlet concentration or in the volumetric gas flowrate. The process can be controlled by means of the regulation of the air flowrate (AFR) to control the oxygen (O2) gas outlet concentration ([O2]out) and the trickling liquid velocity (TLV) to control the H2S gas outlet concentration ([H2S]out). In this work, efforts were placed towards the understanding and development of control strategies in biological H2S removal in a biotrickling filter under aerobic conditions. Classical proportional and proportional-integral feedback controllers were applied in a model of an aerobic biotrickling filter for biogas desulfurization. Two different control loops were studied: (i) AFR Closed-Loop based on AFR regulation to control the [O2]out, and (ii) TLV Closed-Loop based on TLV regulation to control the [H2S]out. AFR regulation span was limited to values so that corresponds to biogas dilution factors that would give a biogas mixture with a minimum methane content in air, far from those values required to obtain an explosive mixture. A minimum TLV of 5.9 m h−1 was applied to provide the nutrients and moisture to the packed bed and a maximum TLV of 28.3 m h−1 was set to prevent biotrickling filter (BTF) flooding. Control loops were evaluated with a stepwise increase from 2000 ppmv until 6000 ppmv and with changes in the biogas flowrate using stepwise increments from 61.5 L h−1 (EBRT = 118 s) to 184.5 L h−1 (EBRT = 48.4 s). Controller parameters were determined based on time-integral criteria and simple criteria such as stability and oscillatory controller response. Before implementing the control strategies, two different mass transfer correlations were evaluated to study the effect of the manipulable variables. Open-loop behavior was also studied to determine the impact of control strategies on process performance variables such as removal efficiency, sulfate and sulfur selectivity, and oxygen consumption. AFR regulation efficiently controlled [O2]out; however, the impact on process performance parameters was not as great as when TLV was regulated to control [H2S]out. This model-based analysis provided valuable information about the controllability limits of each strategy and the impact that each strategy can have on the process performance.
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Infante-Castillo, Ricardo, and Samuel P. Hernández-Rivera. "Predicting Heats of Explosion of Nitroaromatic Compounds through NBO Charges and 15N NMR Chemical Shifts of Nitro Groups." Advances in Physical Chemistry 2012 (August 30, 2012): 1–11. http://dx.doi.org/10.1155/2012/304686.
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This work presents a new quantitative model to predict the heat of explosion of nitroaromatic compounds using the natural bond orbital (NBO) charge and 15N NMR chemical shifts of the nitro groups (15NNitro) as structural parameters. The values of the heat of explosion predicted for 21 nitroaromatic compounds using the model described here were compared with experimental data. The prediction ability of the model was assessed by the leave-one-out cross-validation method. The cross-validation results show that the model is significant and stable and that the predicted accuracy is within 0.146 MJ kg−1, with an overall root mean squared error of prediction (RMSEP) below 0.183 MJ kg−1. Strong correlations were observed between the heat of explosion and the charges (R2 = 0.9533) and 15N NMR chemical shifts (R2 = 0.9531) of the studied compounds. In addition, the dependence of the heat of explosion on the presence of activating or deactivating groups of nitroaromatic explosives was analyzed. All calculations, including optimizations, NBO charges, and 15NNitro NMR chemical shifts analyses, were performed using density functional theory (DFT) and a 6-311+G(2d,p) basis set. Based on these results, this practical quantitative model can be used as a tool in the design and development of highly energetic materials (HEM) based on nitroaromatic compounds.
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Ye, Congliang, and Qi Zhang. "Optimal Falling Track Design for Twice detonating Fuze of Double event Fuel air Explosive with High Speed." Defence Science Journal 70, no. 4 (July 13, 2020): 366–73. http://dx.doi.org/10.14429/dsj.70.14868.
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To prevent the initiation failure caused by the uncontrolled fuze and improve the weapon reliability in the high-speed double-event fuel-air explosive (DEFAE) application, it is necessary to study the TDF motion trajectory and set up a twice-detonating fuze (TDF) design system. Hence, a novel approach of realising the fixed single-point center initiation by TDF within the fuel air cloud is proposed. Accordingly, a computational model for the TDF motion state with the nonlinear mechanics analysis is built due to the expensive and difficult full-scale experiment. Moreover, the TDF guidance design system is programmed using MATLAB with the equations of mechanical equilibrium. In addition, by this system, influences of various input parameters on the TDF motion trajectory are studied in detail singly. Conclusively, the result of a certain TDF example indicates that this paper provides an economical idea for the TDF design, and the developed graphical user interface of high-efficiency for the weapon designers to facilitate the high-speed DEFAE missile development.
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Smalii, V., and E. Tolok. "MODEL OF MULTICOMPONENT LIQUID POOL EVAPORATION FORMED DUE ACCIDENTAL SPILLS." Ecological Safety and Balanced Use of Resources, no. 2(26) (March 5, 2023): 122–32. http://dx.doi.org/10.31471/2415-3184-2022-2(26)-122-132.
Full textAbstract:
Quantitative analysis and assessment of technogenic risk imply a thorough study of the emergency process at the level of phenomenology. In the process of such a study, mathematical models of the physical and chemical processes of the formation of a hazardous substance in the surrounding space, the occurrence and influence of damaging factors on recipients, which are people, the environment, buildings and equipment, are involved. One of the most common scenarios for the formation of a hazardous substance in the environment is the spillage of a liquid phase, often of a multicomponent composition, onto the earth's surface. The subsequent evaporation of a hazardous substance is a key factor in the formation of an explosive, flammable or toxic cloud. Therefore, it is extremely important to correctly assess the intensity of the release of a hazardous substance into the environment.
This study presents a mathematical model for the evaporation of a multicomponent liquid from the surface of an emergency spill, taking into account external energy flows that affect the evaporation process (heat flow from atmospheric air, heat flow from the underlying surface, radiation flow from the sun). The effect of cooling due to evaporation is taken into account. The developed model takes into account the mutual influence of the component composition of the liquid phase and the evaporation process. A comparative analysis of the simulation results was made with the published experimental data on the processes of evaporation of a cryogenic liquid (nitrogen) and liquids under non-boiling conditions such as ethanol and cyclohexane. The results of the comparison showed the applicability of the model in the field of quantitative risk analysis and assessment, and also revealed ways to improve the mathematical model of the multicomponent liquid pool evaporation.
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Barozzi, Marco, Sabrina Copelli, Martina Silvia Scotton, and Vincenzo Torretta. "Application of an Enhanced Version of Recursive Operability Analysis for Combustible Dusts Risk Assessment." International Journal of Environmental Research and Public Health 17, no. 9 (April 28, 2020): 3078. http://dx.doi.org/10.3390/ijerph17093078.
Full textAbstract:
Organic dust explosions were and are still today a critical issue in the food, pharmaceutical, and fine chemical industry. Materials such as flour, corn starch, sugar and APIs represent a cause of severe accidents. In this framework, we investigated a modified version of Recursive Operability Analysis−Incidental Sequence Diagrams (ROA–ISD), called ROA Plus−ISD, specifically tailored to describe industrial processes involving organic combustible dusts. Compared to more classical techniques such as Hazard and Operability (HazOp), ROA−ISD allows for a direct generation of fault trees, providing a useful tool to connect Qualitative with Quantitative Risk Analysis (QRA). ROA Plus−ISD is very similar to ROA−Cause Consequence Diagrams (CCD), which has already proven to be an effective tool to perform both risk assessment on existing plants and reconstructing already occurred accidents, given its logical structure and width of the application fields. In this work, we modified specific parts of the standard ROA−CCD method: (1) the Failure Mode and Operability Analysis (FMEA) database has been structured in order to retrieve the well-known explosion pentagon (for dusts) and all the instruments, devices, apparatuses and controllers typical of industries which process organic dusts; (2) a new comprehensive list of process variables has been compiled. In this way, it is possible to tailor the information required for the generation of the fault trees concerning top events involving mainly dust explosions and fires. This method has been implemented in order to reconstruct the dynamics of the February 2008 Imperial Sugar refinery plant accident (Port Wentworth, GA, USA). Results demonstrated the applicability of the enhanced method by highlighting the criticalities of the process already showed by a previously detailed reconstruction performed by the Chemical Safety Board.
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Górniak, Katarzyna, Tadeusz Szydłak, Piotr Wyszomirski, Adam Gaweł, and Małgorzata Niemiec. "Recently Discovered Thick Bentonite Bed Hosted by the Lithothamnium Limestones (Badenian) in the Polish Part of the Carpathian Foredeep: The Evidence for Volcanic Origin." Minerals 11, no. 12 (December 15, 2021): 1417. http://dx.doi.org/10.3390/min11121417.
Full textAbstract:
In this paper, we discuss the hypothesis on the volcanic origin of the precursor sediments for a thick (0.6 m) clay bed, hosted by the sequence of lithothamnium limestones of the Pińczów Formation. Combined X-ray powder diffraction, imaging methods (optical and electron microscopy), and chemical analysis were used to document the volcanic markers, which were preserved in the rock studied. The results obtained show that the clay bed discussed is bentonite in origin. This bentonite, which can be called Drugnia Rządowa bentonite, is composed almost entirely of montmorillonite with little admixtures of quartz and biotite. A small amount of calcite is present, but only in the top of the bed. Despite that, the bentonite contains nothing but clay material—it is a model example of entirely altered pyroclastic rock, which retains texture originally developed in volcanic glass fragments and reveals the preserved original features of the precursor fallout pyroclastic deposits (rhyolitic in character). The thick bentonite beds, discovered for the first time within the Badenian lithothamnium limestones of the Pińczów Formation, can be considered as a record of a violent, explosive volcanic event related to the closure of the Outer Carpathian basin and the development of the Carpathian Foredeep.