Probability Of Explosion Research Articles

Study on Oxygen Balance Regulation of TKX‐50 Based on Emulsion Method

AbstractDuring the process of external work, the energy of the negative oxygen balanced 5,5′‐Bi‐tetrazolium‐1,1′dioxyhydroxylammonium salt (TKX‐50) is not fully released, resulting in low energy utilization efficiency and the generation of harmful gases that pollute the environment. Based on this, in order to adjust the oxygen balance of TKX‐50, nano TKX‐50/AP composites with positive, zero and negative oxygen balance were prepared by emulsion method. The morphology of nano TKX‐50/AP composite was similar to that of hedgehog‐like spherical‐like particles, with many dense pores formed on the surface, and the average particle size was about 30 μm. During the composite process, part of TKX‐50 reacted with AP to form 5,5′‐bistetrazole‐1,1′dioxidamide (ABTOX). The first thermal decomposition peak temperature of zero‐oxygen balance TKX‐50/AP composite was 236.0°C, which was slightly reduced compared with that of TKX‐50. The second thermal decomposition peak temperature was 275.1°C, which was 22.2°C higher than that of TKX‐50. The heat release of zero‐oxygen balance TKX‐50/AP composite reached 2206 J g−1, which increased by 35.9% compared to TKX‐50, and the energy utilization efficiency was also greatly improved. The drop height of 50% explosion probability (H50) of zero‐oxygen balance TKX‐50/AP composite was 63.5 cm, and the explosion probability of friction sensitivity was 72%. Compared with TKX‐50, it increased by 15.1 cm and decreased by 28%, respectively. The results showed that the mechanical safety performance of TKX‐50 had been improved.

Effects of aging on mechanical sensitivity threshold and thermal decomposition characteristic of RDX/HMX

In order to analyze the influences of storage aging on the safety of typical elemental explosives, the aged cyclotrimethylene trinitramine (RDX) and cyclotetramethylene tetranitramine (HMX) were prepared by isothermal aging tests. The reaction thresholds of aged RDX and HMX under any ignition probability were studied by Langlie-Optimal D method. The thermal decomposition characteristics of RDX and HMX after aging were analyzed by DSC and ARC. Experimental results showed that compared with unaged RDX and HMX, on the one hand, the critical impact energy and critical friction of RDX and HMX aged for 14, 28 and 56 days are significantly reduced at an explosion probability of 50%, 0.01% and 0.0001%, respectively. With the increase of aging time, the mechanical sensitivity of RDX and HMX increases obviously. On the other hand, the initial decomposition temperature of RDX and HMX after 56 days of aging decreases, the decomposition heat decreases, the activation energy increases, and the reaction difficulty increases.

Dynamic risk evolution analysis for in-situ combustion incidents of offshore heavy oil recovery

In-situ combustion for offshore heavy oil involves significant risk factors related to ignition, gas injection, and corrosion prevention, especially under challenging operating conditions. If not properly managed, these risks can lead to explosions in injection or production wells. This paper proposes a hybrid HDBN-based risk analysis method to estimate the probability of explosions during the three critical phases of in-situ combustion and to diagnose key risk factors contributing to such incidents. The method introduces new bootstrap terms to in-situ combustion and constructs a hybrid DBN to capture the dynamic behavior of explosion incidents. It incorporates the Delphi method and triangular Pythagorean fuzzy theory to address data scarcity and uncertainty through affiliation and uncertainty functions. A key aspect of the proposed method is the graded quantification of damage to the casing due to corrosion and thermal stresses. A case study of a well in Liaodong Bay, Bohai Sea, demonstrates the feasibility of this method. The study captures dynamic risk evolution characteristics during three stages of in-situ combustion and conducts sensitivity analysis to obtain key risk factors such as "bottom high temperature" and "gas corrosion".

Risk Analysis of Jet A-1 Tank Filling and Storage Processes at the Shorebase

Coastal Logistics Centers (CLS) provide logistics support to deep-sea drilling operations. Jet A-1 (helifuel), required for helicopters that transfer personnel to drilling ships, is filled into tanks from the tanker arriving at CLS and stored in open areas. Jet A-1 is a hazardous chemical with flammable and toxic effects and can also explode when exposed to flame. Risk analysis of this hazardous chemical is essential for CLS. This study aimed to determine the process hazards and risk analysis in the filling and storage operation of Jet A-1 from tankers to tanks. For this purpose, the Preliminary Hazard List (PHL) and Preliminary Hazard Analysis (PHA) were performed. Then, a Hazard and Operability (HAZOP) study was carried out based on these analysis results. The HAZOP study identified Jet A-1 overflow from the tank as a high-risk event. Afterward, Event Tree Analysis (ETA) was performed on the initial event of Jet A-1 spilling due to tank overflow. In ETA analysis, immediate ignition, delayed ignition, and explosion probabilities resulting from delayed ignition were calculated with the CCPS (Center for Chemical Process Safety) Module. The probability and frequency values of accident scenarios were calculated as P=0.0028, f=1.736 x10-4 year-1 for jet fire, P=0.0225, f=1.395x10-3 year-1 for vapor cloud explosion, P=0.127, f=7.874x10-3 year-1 for flash fire, P=0.847, f = 0.0525 year-1 for toxic release, respectively. It was determined that all accident scenario frequency values were above the legislation threshold value (10-4 year-1). Design solutions and preventive measures have been proposed to reduce risks. The combination of risk analysis methods is effective in risk assessment studies.

Mussel-inspired poly-norepinephrine coatings as “slippy-sticky interlayer” for fabricating high-energy insensitive energetic composites

Inspired by the super-adhesive properties in marine mussel, a desensitized energetic powder constituted of a slippy-sticky polynorepinephrine interlayer and CL-20 microcore is reported. The slow polymerization process enables the extremely smooth and multifunctional thin-coating formed onto the CL-20 surface. Based on the designed composites, the calculated electronic energy values of all 15 optimized structures reveals a spontaneous thermodynamic process and a stronger bonding strength with the increase of polymerization degree. The H50values of NE/CL-20 structure are calculated and show a significant increase for new composite, produced by the bonding of norepinephrine with CL-20, versus pure CL-20. The subsequent experimental results demonstrate that the slippy CL-20@polynorepinephrine structure exhibits a high drop height (H50, 35.5 cm) and a low explosion probability (60 %) than that of pure CL-20, even exhibits a considerable increase and decreases by 13.3 cm and 12 % in turn versus CL-20@polydopamine under the identical experimental conditions. The sensitive simulation results indicate that the shorter NN bond length and lower area percent in electrostatic potential of samples are positively correlated with the decreasing of impact sensitivity. Note that the ultrasmooth bionic interlayer gives the super-adhesive properties of energetic powder, greatly improves the coating degree of 2D material, thereby shows a lower sensitivity and a high detonation heat for the constructed double-coating composites (CL-20@PNE@GO). To sum up, this study will provide an innovative route to construct a high-safety powder based on a bionic sticky interlayer strategy.

Effect of Cubic Crystal Morphology on Thermal Characteristics and Mechanical Sensitivity of PYX

To investigate the influence of the cubic crystal morphology on the thermal properties and sensitivity of 2,6-bis(picrylamino)-3,5-dinitropyridine (PYX), cubic PYX (CPYX) crystals were prepared using the antisolvent method. Scanning electron microscopy (SEM), laser particle size analysis, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the morphology, particle size and structure of the prepared products. The thermal behavior, thermal decomposition kinetics, thermal safety parameters and thermal decomposition mechanism of CPYX were investigated by differential scanning calorimetry–thermogravimetry–mass spectrometry–Fourier transform infrared spectrometry (DSC-TG-MS-FT-IR) and in situ FT-IR experiments. Meanwhile, the mechanical sensitivity of CPYX was determined by means of the explosion probability method. The results showed that the product had a smooth cubic morphology and small crystal aspect ratio with an average particle size (d50) of 10.65 μm, but it had no distinct differences from the crystal structure of raw PYX (RPYX). The thermal decomposition peak temperature, the self-accelerating decomposition temperature and the critical temperature of the thermal explosion of CPYX increased by 7.2 °C, 6.1 °C and 10.4 °C, respectively, compared to RPYX. Similarly, the apparent activation energy increased by 15%. Besides these, the impact sensitivity and friction sensitivity of CPYX decreased by 36% and 20%, respectively, compared to RPYX. The decomposition process of CPYX contains two stages. The first stage involves the breakage of N-H bonds and -NO2 groups with the release of CO2, N2O, NO, HCN and H2O, followed by the thermal decomposition of the resulting intermediate and the release of CO2, N2O and HCN in the second stage.

Spherical core-shell CL-20@LLM-105 composites with excellent mechanical sensibility obtained by Pickering emulsion

The effect of crystallization conditions on the morphology, particle size and dispersibility of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) was investigated by solvent-nonsolvent method, and nano-LLM-105 was successfully prepared and used as a surfactant after modification with stearic acid. A spherical core-shell composites of CL-20@LLM-105 was prepared by Pickering emulsion method. The morphology, crystal structure, and thermal decomposition properties were characterized by scanning electron microscopy (SEM), powder X-ray diffractometry (XRD), differential scanning calorimetry (DSC), fourier transform infrared (FT-IR) tested for impact and friction sensibility. The results showed that the prepared composites had a particle size of 50–100 μm, a spherical core-shell structure, and nano-LLM-105 was encapsulated on its surface. The peak thermal decomposition temperature of the composites was 252.7 ℃, which was 9.4 ℃ higher than that of the raw material CL-20. Compared with the CL-20/LLM-105 mixture with the same ratio, the characteristic drop height (H50) of the CL-20@LLM-spherical compoe-shell site was increased by 13 cm, and the explosion probability (P) was reduced by 43%. The spherical core-shell composites prepared by this method is characterized by high energy and excellent mechanical sensibility, which is expected to provide new ideas for the design of explosive formulations containing CL-20 and nanoenergy-containing materials in the direction of high safety and high energy.

Assessing the speculative dynamics and determinants of residential apartment rentals in Mogadishu, Somalia: A hybrid modeling approach

There has been relatively rapid growth in Somalia's real estate sector recently, resulting in property market booms in major cities of the country. Despite this sector's importance, very little scientific research has been conducted. Thus, this study aims to model the rental value of residential apartments in Mogadishu, Somalia. A hybrid modeling approach is utilized, in which a hedonic regression model was used in the first phase and an Artificial Neural Network (ANN) in the second. After analysis, the study established that an apartment's age, size, value, view, number of toilets, air quality, proximity to CBD, proximity to a university and probability of explosion are key factors determining apartment rental rates in Mogadishu, while floor level, parking space, and school proximity do not have a significant impact on apartment rental rates. Because of speculation, there is a higher likelihood of overvaluation than undervaluation in the housing market, which has profound policy and practical implications. Rather than being driven by real demand, Mogadishu's real estate market is driven by speculation, as overvaluation signals are more evident than undervaluation signals. As one of the world's poorest nations, where 70% of the population lives below the international poverty line, and about 80% of jobs are in the informal sector, extreme speculative activities adversely affect Somalia's economic quality and the living conditions of its citizens. Somali citizens need government policies that facilitate the accessibility, affordability, and adequate availability of decent housing. The study recommends protecting Somalia's real estate sector to attract more investors and boost the country's post-conflict development initiatives. A vital contribution of the study is that it is the first to examine the rental value of residential apartments in Mogadishu systematically. This study contributes significantly to housing economics and real estate development literature.

An experimental study on droplet quench and steam explosion in boric acid solutions

Boric acid (H3BO3) is widely adopted as an additive in the coolant of light water reactors for reactivity control, but its effect on fuel coolant interactions (FCI) during severe accidents (especially on steam explosion) was rarely investigated. To examine the effect of the boric acid additive in coolant on steam explosion, a series of molten droplet-coolant interaction tests using H3BO3 solutions (with concentration ranging from 0–3.2% by weight) is carried out in the present study. The characteristics of melt-coolant interactions are the occurrence probability of typical phenomena (no fragmentation, minor fragmentation, or spontaneous steam explosion), lateral deformation ratio, quench depth, pressure impulse and debris particle size distribution. The statistical data of such characteristics are obtained through repeating 20 runs of the same test category. The experimental results show that the H3BO3 addition in coolant has various impacts on the above-mentioned characteristics of melt-coolant interactions, depending on the H3BO3 concentration. In particular, the probability of steam explosion sightly decreases as the H3BO3 concentration increases from zero to 1.2 wt.%, but significantly increases as the H3BO3 concentration further increases to 3.2 wt.% trough 2.2 wt.%. Namely, the inhibiting effect of boric acid on steam explosion is diminishing with increasing H3BO3 concentration beyond 1.2 wt.%. It is also found that both melt and coolant temperatures are crucial parameters impacting the likelihood and energetics of steam explosion.

Probabilistic risk assessment of fire and explosion of onboard high-pressure hydrogen system

Hydrogen is regarded as a new energy carrier and has broad application prospects. As the leading field of hydrogen energy application, hydrogen fuel cell vehicles (HFCVs) are highly valued in the world. However, due to the flammable and explosive characteristics of hydrogen, its safety issues have attracted much attention, and it is increasingly necessary to understand the possible accident risks of the hydrogen system of HFCVs. In this study, the quantitative risk assessment (QRA) of hydrogen system of HFCV was carried out, and the Bayesian network (BN) analysis model of fire and explosion risk of onboard high-pressure hydrogen system was established. Taking a hydrogen system as an example, BN parameters are quantified based on three quantitative analysis methods: general data, logical judgment and computational simulation, and then the fire and explosion risk and personnel loss degree of the general onboard high-pressure hydrogen system are determined. The results show that when hydrogen release occurs, the probability of explosion is 6.79E-05, the probability of jet fire is 1.53E-04, and the probability of fireball is 5.38E-08. In the case of major damage, there is an 87.15 % probability that an explosion occurred; the reliability of safety protection devices is very important in the process of hydrogen use. It is suggested to optimize the structural layout design of safety components and improve the reliability of protection devices to promote the safe development of hydrogen energy industry such as HFCVs.

An experimental study on the effect of chemical additives in coolant on steam explosion

In assessment of severe accident risk in light water reactors (LWRs), steam explosion is a nonnegligible phenomenon following a relocation of core melt (corium) into coolant, and thus various research efforts have been paid to steam explosion. There had been numerous studies showing that the occurrence of steam explosions is influenced by several factors such as melt and coolant temperatures, melt materials, non-condensable gasses, etc. However, most of the existing experiments used deionized (DI) water or tap water as coolant, with little consideration of the effect of chemicals (e.g. boric acid, sodium hydroxide, sodium phosphate) commonly applied in reactor coolant. To examine the effect of the chemical additives in coolant on steam explosion, the present study performs a series of molten Tin droplet-coolant interaction tests using DI water and different chemical solutions, including H3BO3 solutions, NaOH + H3BO3 neutral solutions, and Na3PO4 + H3BO3 neutral solutions. The experimental results show that adding NaOH and Na3PO4 in boric acid solution significantly affects the occurrence probability of spontaneous steam explosion, because of the presence of PO43− and H+ ions. When different solutions have equivalent concentrations of H3BO3, the peak pressure values of the spontaneous steam explosion of Sn droplets are similar among various solutions. Compared with those in DI water, steam explosion in the chemical solutions occurs predominantly within a narrow range of depth from 28 mm to 40 mm and produces a much higher peak pressure. This implies that more energetic steam explosions may occur in the chemical solutions.

Facile Recrystallization Process for Tuning the Crystal Morphology and Thermal Safety of Industrial Grade PYX.

In this study, the crystal appearance of industrial grade 2,6-diamino-3,5-dinitropyridine (PYX) was mostly needle-shaped or rod-shaped with an average aspect ratio of 3.47 and roundness of 0.47. According to national military standards, the explosion percentage of impact sensitivity s about 40% and friction sensitivity is about 60%. To improve loading density and pressing safety, the solvent-antisolvent method was used to optimize the crystal morphology, i.e., to reduce the aspect ratio and increase the roundness value. Firstly, the solubility of PYX in DMSO, DMF, and NMP was measured by the static differential weight method, and the solubility model was established. The results showed that the Apelblat equation and Van't Hoff equation could be used to clarify the temperature dependence of PYX solubility in a single solvent. Scanning electron microscopy (SEM) was used to characterize the morphology of the recrystallized samples. After recrystallization, the aspect ratio of the samples decreased from 3.47 to 1.19, and roundness increased from 0.47 to 0.86. The morphology was greatly improved, and the particle size decreased. The structures before and after recrystallization were characterized by infrared spectroscopy (IR). The results showed that no chemical structure changes occurred during recrystallization, and the chemical purity was improved by 0.7%. According to the GJB-772A-97 explosion probability method, the mechanical sensitivity of explosives was characterized. After recrystallization, the impact sensitivity of explosives was significantly reduced from 40% to 12%. A differential scanning calorimeter (DSC) was used to study the thermal decomposition. The thermal decomposition temperature peak of the sample after recrystallization was 5 °C higher than that of the raw PYX. The thermal decomposition kinetic parameters of the samples were calculated by AKTS software, and the thermal decomposition process under isothermal conditions was predicted. The results showed that the activation energy (E) of the samples after recrystallization was higher by 37.9~527.6 kJ/mol than raw PYX, so the thermal stability and safety of the recrystallized samples were improved.

The influence of melt composition, liquidus temperature and solidus temperature on vapour explosions in melt droplet impingement experiments

For the investigation of vapour explosions, droplet impingement experiments were performed with the binary system Pb–Sn and the pseudo-binary system PbS–Cu2S. The experiments were performed with a melt at 600 °C (Pb–Sn) or 700 °C (PbS–Cu2S) and a water bath at ambient temperature and pressure. A hydrophone and a high-speed camera were used to study the interaction and from this data, the explosion probability and intensity were determined.The explosion probability had a single minimum around 70 wt% Sn, close to the eutectic composition. Moreover, the explosion probability increased approximately linearly with changing composition towards the pure melts, and was similar for pure tin and pure lead. On the other hand, the explosion intensity was comparable for tin and the eutectic alloy while clearly lower for lead. Almost all intermediate alloys had a reduced explosion intensity.Based on the variation in composition, the effects of the liquidus or solidus temperature and the liquidus-solidus gap on the explosion behaviour were also investigated. The explosion probability in both systems increased with increasing liquidus temperature. Also, the maximum explosion intensity in the Pb–Sn system increased with increasing liquidus temperature. Both could be related to easier triggering due to (partial) solidification. On the other hand, the explosion intensity was found to decrease with increasing gap between liquidus and solidus temperature, as was also found in literature. No significant trends for the explosion intensity were found for experiments with PbS–Cu2S.

The impact assessment of accidental explosions of large constellations on low earth orbit environment

Because of its large number of satellites, a large constellation (a LC) greatly affects other objects in LEO. Several studies reveal the impact of a LC in LEO missions in various operational scenarios. This study evaluated the environmental impact of a LC explosion in the short and long-term using the Near-Earth Orbital Debris Environment Evolutionary Model (NEODEEM). Although setting mission scenarios and analysis conditions is important in LC simulations, it is difficult to consider all operational scenarios due to the many combinations. Therefore, this study conducted impact assessments of explosions in a LC, concentrating on the number of explosions, orbital altitude, and scaling factor of the explosions. The results indicated that it is not enough for LC to comply with the current requirement of probability of accidental explosions which is less than 0.001 during the operation. This is because, if the rate is applied directly to a LC with thousands of satellites, continuous explosions (i.e., several satellites explode every year) will occur during the mission duration of LC. The paper also discusses the behavior of fragments from explosions at different altitudes. The explosions at low altitudes have no significant impact in the long term, although it can cause an incremental change in collision risk in the short term. Similarly, the explosions at high altitudes, such as 1,250 km, have only slightly increments of the expected number of collisions, but its impact could last for over 100 years. The probability of explosions of a LC must be carefully determined through a series of simulations based on the number of satellites and the operational orbit of a LC. This paper also discusses what should be considered in future LC design and operations regarding explosion prevention.

Analysis of the Relationship between Selected Ship and Propulsion System Characteristics and the Risk of Main Engine Turbocharger Explosion

The scientific aim of this paper is to analyse the topicality of the turbocharger explosions and to attempt to answer the question of whether some technical characteristics of the engine can be perceived as directly connected with the risk of the turbocharger explosion. Moreover, our objective was also to calculate the turbocharger explosion probability. This article presents the results of a quantitative and qualitative analysis of 42 explosions of marine main engine turbochargers occurring between 1977 and 2022. The number of explosions was analysed, and the average and instantaneous frequencies of turbocharger explosions each year were determined. An analysis was performed of the number of explosions with respect to the age and type of ship on which the accident occurred. An analysis of the contribution of different types of main engine to the studied population of explosions was also carried out. Criteria such as the number of strokes, engine speed, type of crank-piston mechanism, cylinder arrangement, engine power per cylinder, and number of cylinders were considered. An analysis was carried out of the disasters that had occurred, considering the contribution of the various engine manufacturers. An integrated distribution of the number of turbocharger explosions by year was presented, considering the engine speed, the maximum continuous rating of the engine, and the engine design. The analysis did not indicate a significant correlation between the type of ship and the number of explosions that occurred. More than half of the analysed population of explosions (median) occurred on vessels no older than 15 years. It is highly likely that engine type does not directly affect the number of turbocharger explosions and the risk of explosions. On the other hand, it is not possible to exclude the influence of the individual characteristics of an engine built to a particular manufacturer’s design on the magnitude of the risk of a turbocharger exploding during engine operation. Considering the number of ships worldwide, the probability of an explosion in a given year on a given ship is not less than 1.61 × 10−7.

Study on quantitative risk assessment of girth weld failure of natural gas pipeline based on reliability

In order to avoid safety accidents caused by the failure of welding girth weld of long-distance gas pipeline, carry out quality investigation of girth weld of in-service pipeline, and perform quantitative risk assessment based on reliability for girth weld with difficulty in excavation, to effectively improve the effectiveness and economy of excavation point selection. In this study, using the probability-based weld structure failure prediction method through girth weld X-ray inspection results during the construction period, calculate the probability of fire and explosion due to leakage/rupture of girth welds in the natural gas pipeline and the impact range based on the basic risk evaluation information such as external environment and personnel distribution in the area of the pipe section where the welds are located. Identify excavation plan based on the evaluation results, and propose effective risk mitigation measures for nonexcavation sites. In the end, practical application cases are listed.

A study of hydrogen leak and explosion in different regions of a hydrogen refueling station

The consequences of hydrogen leaks and explosions are predicted for the sake of the safety in hydrogen refueling stations. In this paper, the effect of wind speed on hydrogen leak and diffusion is analyzed in different regions of a hydrogen refueling station, and the influence of delayed ignition time on hydrogen explosion after an accidental hydrogen leak is further studied by numerical simulation. Results show that the effect of wind speed on the probability of hydrogen fires is distinctive in different regions of hydrogen refueling station. The size of combustible clouds in the trailer front region and the outer region increases in the low wind speed case, and the front of combustible clouds is formed in a spherical shape in the outer region, which can greatly increase the probability of hydrogen explosion. However, the high wind speed may cause an increase of the risk of accidents in the near ground region. Moreover, a non-linear correlation is shown between the rate of combustible cloud dissipation and wind speed after the hydrogen stops leaking. In addition, it is found that an increase in delayed ignition time may lead to an increase in explosion intensity, which is related with the larger high temperature area and stronger explosion overpressure. Two flame fronts and the reverse propagation of the explosion overpressure can be observed, when the delayed ignition time is larger.

Dynamic Bayesian network risk probability evolution for third-party damage of natural gas pipelines

Failure and leakage of natural gas pipelines can lead to serious ecological losses and casualties. Third-party damage has become an important cause of pipeline failure and leakage, which urgently needs an accurate risk assessment method to assess the risk. Conventional qualitative risk analysis methods can only point out the critical events of failure accidents but fails to predict the failure probability. This paper proposes a dynamic risk probability analysis method based on Dynamic Bayesian network (DBN), which is validated by a third-party damage case under uncertainty. First, human factors are taken as the main analysis object in the risk analysis, by which two subcategories of intentional and unintentional factors are classified. A complete risk factor analysis is performed by combining expert recommendations with the fault tree analysis method and developing a coupled model with the event sequence diagram. Second, in order to deal with the uncertainty of risk factors, the coupled model is mapped to a DBN model. The prior probabilities of the input DBN model are obtained by database, fuzzy set theory, and Dempster-Shafer evidence theory. Weibull distribution is applied to construct the probability transfer process between time segments, which better fits the characteristics of third-party disruptive factors in onshore pipelines. Finally, the practicality and advantages of the proposed method are demonstrated by a real case study, which identifies 6 critical events and predicts the probabilistic information in different time slices. Furthermore, the method predicts the probability of failure events and potential consequences by processing the time series information, and it is found that the probability of structural damage and explosion is higher than other consequences. In this way, some risk management countermeasures are proposed in a targeted manner. The results show that compared with the conventional BN model which only performs probabilistic inference once, the DBN model can perform temporal dynamic inference to achieve the prediction of failure probability, and it can effectively achieve the numerical prediction of risk failure probability.

A Study on High‐Quality RDX‐Based Flexible Explosives with High Energy and Low Vulnerability

AbstractA new type of flexible explosive(HFE) with high energy and low vulnerability based on H‐RDX(High‐quality RDX) was proposed. Fundamental characterizations of H‐RDX, including infrared testing and particle size measurement, were carried out. The technological parameters of the process were researched. Mechanical sensitivities were characterized by impact sensitivity tester and friction sensitivity tester on the base of the explosion probability method. Energetic properties containing densities, initiation properties, and detonation velocities were investigated. For comparison, normal RDX was introduced. It is concluded that HFE with great flexibility was obtained under the sulfuration condition of 80 °C, 10d. The surface of H‐RDX is smoother with fewer defects and a smaller specific surface, leading to the better safety performance of HFE. The impact and friction sensitivities of HFE were 50 % and 22 % less than those of RDX‐based flexible explosive, respectively. Moreover, higher densities and a 6∼19 % rise in detonation velocities indicate that HFE(6700∼7500 m ⋅ s−1) has better energy performance. The precise incision was realized as the dosage of HFE rose(thickness, from 3 mm to 5 mm). The waterproofness of HFE was also tested by the detonation of the sample(submerged in 1 m water for 24 h) with the optimum proportion of the formula(explosive/rubber/functional agents=92/6/2). An excellent application prospect of the flexible explosive was observed in this work.

Research on Mechanical Properties and Sensitivity of a Novel Modified Double-Base Rocket Propellant Plasticized by Bu-NENA.

The research and development of rocket propellants with a high solid content and superior mechanical and security performance is urgently needed. In this paper, a novel extruded modified double-base (EMDB) rocket propellant plasticized by N-butyl-N-nitratoethyl nitramine (Bu-NENA) was prepared to overcome this challenge. The results indicated that Bu-NENA decreased the mechanical sensitivity successfully, contributing to the mechanical properties against traditional nitroglycerin (NG) based EMDB propellants, while hexogen (RDX), which is beneficial to propellant energy, was not conducive to the elongation and sensitivity of the propellants. By contrast with the blank group (NG-based EMDB propellant, R0), the elongation of the optimized propellant at −40 °C was promoted by 100% from 3.54% to 7.09%. Moreover, the β-transition temperature decreased from −33.8 °C to −38.1 °C due to superior plasticization by Bu-NENA, which represents a better toughness. The friction sensitivity dropped by 100% from 46% to 0%. Simultaneously, the height for 50% probability of explosion (H50) increased by 87.2% from 17.2 cm to 32.2 cm. The results of this research could be used to predict a potential prospect in tactical weapons.