Search Results (249)

Repeated exposure to low-level blast overpressure (BOP) during controlled detonations is an emerging occupational health concern for military breachers and Special Operations Forces personnel, given accumulating evidence that chronic exposure may produce subtle, subclinical neurotrauma. This study derived a latent neuroinjury construct integrating three complementary domains of brain health—post-concussive symptoms, working-memory performance, and circulating biomarkers—to determine whether breachers exhibit coherent patterns of neurobiological alteration. Symptom severity was assessed using the Rivermead Post-Concussion Questionnaire (RPQ), and working memory was assessed with the N-Back task and a panel of thirteen neuroproteomic biomarkers was measured reflecting astroglial activation, neuronal and axonal injury, oxidative stress, inflammatory signaling, and neurotrophic regulation. Experienced Canadian Armed Forces breachers with extensive occupational BOP exposure were compared with unexposed controls. Bayesian latent-variable modeling provided probabilistic evidence for a chronic, subclinical neurobiological signal, with the strongest contributions arising from self-reported symptoms and smaller but consistent contributions from the biomarker domain. Working-memory performance did not load substantively on the latent factor. Several RPQ items and circulating biomarkers showed robust loadings, and the latent neuroinjury factor was elevated in breachers relative to controls (97% posterior probability). The pattern is broadly consistent with subclinical neurobiological stress in the absence of measurable cognitive impairment, suggesting early or compensated physiological alterations rather than overt dysfunction. This multidomain, biomarker-informed framework provides a mechanistically grounded and scalable approach for identifying subtle neurobiological strain in military personnel routinely exposed to repetitive low-level blast. It may offer value for risk stratification, operational health surveillance, and the longitudinal monitoring of neurobiological change in high-risk occupations. Full article

Test fires of a rotating detonation engine (RDE) annular combustor operating on a methane–oxygen mixture were conducted. Compared to the original RDE combustor previously tested, it was modified in terms of changing the layout of the water cooling system, the positions of ports for sensors, and the shape of the supersonic nozzle. The stable operation process with a single detonation wave continuously rotating in the annular gap with the velocity of ~1900 m/s (rotation frequency of ~6 kHz) was obtained in the wide range of flow rates of propellant components. This is an important distinguishing feature of the present RDE combustor compared to the analogs known from the literature, which usually exhibit an increase in the number of simultaneously rotating detonation waves with an increase in the flow rates of propellant components. Compared to the original RDE combustor, the maximum duration of operation and the attained sea-level specific impulse were increased from 1 to 30 s and from 250 to 277 s, respectively. The thermal states of all heat-stressed elements of the combustor were obtained. The maximum heat fluxes are registered in the water cooling jackets of the central body and the combustor outer wall. Heat losses in the water cooling system are shown to increase with the average pressure in the combustor. The maximum value of the average heat flux over 20 MW/m² is achieved on the combustor outer wall. The average heat flux into the combustor outer wall is approximately 20% higher than that into the central body. The average heat flux into the nozzle is several times lower than similar values for the combustor outer wall and central body. The total heat loss into the water-cooled walls of the combustor reach about 10% of the total thermal power of the combustor. Full article

The article evaluates the impact of blasting operations with explosives on hydrogen sulfide (H₂S) emissions from rock mass in a copper ore mine. The study showed that detonations of explosives cause increased release of H₂S and other gases from the rock mass interior into the mine workings space. Analysis of changes in H₂S concentration over a period of ±60 min relative to the moment of detonation, performed for data from 2014 and 2017, revealed significant differences in gas behavior. In 2014, the average H₂S concentration decreased after the blast, while in 2017, a marked increase was observed, although the absolute values were lower than in the previous period. The average time to reach the maximum concentration of H₂S after an explosion in 2014 was 24 min and 25 s, and in 2017, 29 min and 22 s. Stabilization of the mine atmosphere occurred in 2014 after 58 min and 15 s, and in 2017 after about 40 min and 57 s. In none of the analyzed periods did the concentration values exceed the threshold of 7 ppm, which means that the level of H₂S did not reach the values considered dangerous for the crew. The results indicate that blasting works significantly affect the dynamics of gas release from the rock mass, but do not pose a threat under the conditions studied. Full article

Owing to their superior performance in countering electromagnetic interference on the battlefield, laser fuzes have become a promising candidate for application in munition systems. However, as the short-pulse laser is activated by an electrical signal, the possibility of accidental emissions caused by logic device failure cannot be ruled out, making it vulnerable under the effects of strong electromagnetic coupling. Integrating an encrypted, MEMS-based Safety and Arming Device (SAD) into the energy channel to control the propagation of short-pulse lasers can significantly enhance the safety level of munition systems. In the present work, the effect of MEMS SAD integration on laser propagation is investigated. The results demonstrate that the insertion of a MEMS SAD does not introduce significant attenuation of short-pulse laser propagation. A firing test is conducted using the laser-driven flyer detonator to verify the safety, charging mechanism, and function to provide a comprehensive characterization of the laser fuze. To guarantee the initiation of insensitive explosives, the coupling efficiency and laser transmission energy density of multi-mode quartz fibers are studied. Full article

Transportation activities can constitute up to 70% of a quarry’s total operating costs, making haul roads a critical component of open-pit mine infrastructure. Generally, in-pit haul ramp construction can be accomplished through two primary blasting approaches: either peripheral blasting near the ramp location, or direct blasting at the designed ramp site. In the first method, the blasted material is transported, shaped, and compacted to form an embankment. Conversely, in direct blasting, the blast pattern is specifically designed to generate the ramp geometry, and the resulting muckpile is directed to production, eliminating the need for an embankment. Each method presents distinct operational advantages and inherent limitations. This study investigates the influence of these blasting scenarios, in particular on fume emissions (nitrogen oxides—NO_x—and carbon oxides—CO_x) and deposit management. The assessment encompasses emissions generated both from the detonation of explosives and from the operation of diesel-powered equipment. The findings indicate that the method involving peripheral blasting (bench embankment construction method) produces more than 2.5 times higher nitrogen and carbon oxides emissions compared to blasting works at the exact construction location of the ramp at the Holcim Dubie dolomite open-pit mine. In addition to emission analysis, operational factors related to ramp formation and its subsequent use were evaluated. The results demonstrate that constructing the in-pit haul ramp directly within the rock mass yields approximately 2·10⁶ Mg less fume emissions than the embankment-based method. Furthermore, this approach facilitates the recovery of an additional 150,000 m³ of dolomite for production purposes, thereby enhancing resource efficiency. Collectively, these findings suggest that the direct in-rock ramp construction technique offers superior environmental performance and operational sustainability within the context of open-pit mining practices. Full article

In this study, we investigated the impact of incorporating energetic substituents such as –NO₂, –NH₂, –Cl, –F, N-methyl-N-nitro (CH₃–N–NO₂), and picryl on the detonation performance and stability of acridone-based compounds. The B3LYP/cc-pVTZ approach was applied to investigate the influence of substitutions on the stability and detonation properties of acridone derivatives. The results obtained exhibit the significant influence of both the type and position of substituents on the energetic performance and stability of the compounds studied. Notably, the acridone derivative bearing a picryl group and four –NH₂ substituents exhibited energetic properties superior to those of 2,4,6-trinitrotoluene (TNT). Its calculated velocity lies in the range [7.45–7.66] km/s, and its detonation pressure is [22.49–24.36] GPa; however, its stability is lower than that of core compounds. This reduction, however, is dependent on both the nature and number of substituents introduced. Full article

A computational study is conducted on shock wave propagation and diffraction in an annular duct. The curved geometry and central obstruction of the annular configuration generate complex wave phenomena not typically observed in linear channels. The evolution of incident shock fronts, their interactions with the inner and outer walls, and the resulting diffraction patterns are analysed in detail. Particular focus is placed on the formation of reflected and transmitted waves, as well as the effects of curvature and channel dimensions on shock strength and propagation speed. High-resolution computational fluid dynamics (CFD) simulations are used to capture transient flow features, and results are validated against available experimental data. Simulations are performed across a range of annular geometries with varying radii of curvature and inlet Mach numbers. Simulations across a range of inlet Mach numbers (1.5–3.0) and radii of curvature show that increasing curvature intensifies shock focusing near the inner wall, raising local pressure peaks by up to 20%, while promoting faster attenuation of the transmitted wave downstream. At higher Mach numbers, the reflected shock transitions from regular to Mach reflection, producing triple-point structures. The comparison of shock structures across configurations shows good agreement with experimental observations. The findings enhance understanding of shock dynamics in non-standard geometries and have implications for the design of detonation engines, pulse detonation systems, and safety analyses in confined environments. Full article

Materials with high hardness are critical for industrial and aerospace applications, prompting the search for novel compounds with robust covalent networks. Using a first-principles structure prediction method, we systematically explored the phase stability of Si–N compounds under high pressure. We identified two thermodynamically stable phases: Si₆N with P-1 symmetry and SiN₄ with space group R-3c. Phonon spectra and ab initio molecular dynamics simulations confirm the dynamical and thermal stability of R-3c SiN₄ at ambient pressure and up to 2000 K. Notably, R-3c SiN₄ exhibits exceptional mechanical properties with a Vickers hardness of 31 GPa, a bulk modulus of 259.53 GPa, and a Young’s modulus of 485.38 GPa. Furthermore, SiN₄ possesses a high energy density (1.1 kJ·g⁻¹) and outstanding detonation pressure and velocity (228 kbar, 7.11 km·s⁻¹), both exceeding those of TNT, making it a potential high-energy-density materials. In addition, electronic structure analysis reveals SiN₄ has a band gap of 2.5 eV, confirming its nonmetallic characteristics and strongly covalent nature. These findings provide theoretical guidance for the future synthesis of Si–N phases and establish a foundation for designing novel materials that combine high hardness with high-energy density performance. Full article

Although the accidental or intentional explosions produced in industrial facilities or in urban areas are events with low probability, they have a high destructive potential and potential for human injuries and/or fatalities. One of the types of such events is given by detonation of improvised explosive devices (IEDs)—dirty bombs for terrorist purposes—which may produce a high number of metallic fragments. Studying mass and spatial distributions of these fragments is useful for evaluating their lethality and destructive potential and may help to implement adequate protective measures. This work brings a closer insight into the fragment dispersion around the detonation of a steel-enclosed C4 charge with cylindrical symmetry. In this respect a specific approach involving both detonation experiments and numerical simulations performed by home-made and commercial software packages for investigation of the fragmentation process and accompanying angular scattering of the fragments was proposed. Special algorithms, which allow the estimation of the spatial distributions of fragments from the numerical analysis of perforations made by the metallic fragments generated by such IEDs on surrounding material walls, are developed. Further, numerical simulations of a similar IED device provided output parameters related to the statistical distributions of mass, kinetic energy and position of the fragments. Experimental fragmentation generated a recovered mass distribution (94 fragments of 67.5 g) that was compared with that extracted from simulation, revealing a reasonable agreement on the 0.3–1 g range. In the case of simulations, 300 fragments from a total number of 374 showed a mass ranging from 0.004 to 0.3 g. The simulations showed that the middle part of the steel case generated fragments of kinetic energy over 4 kJ and its ends generated fragments of kinetic energy under 1 kJ. Experimental fragment scattering distributions were investigated with specific home-made numerical algorithms, which, based on a set of images, analysed the correlations between spatial coordinates of perforations made by fragments on surrounding special panels and provided histograms that are discussed in relation with the fragment-induced lethality degree. Full article

This study presents the synthesis and comprehensive characterization of a novel nitroform salt, bis(2-methyl-3-amino-1,2,4-triazolyl)furoxan trinitromethanide (compound 2), derived from the molecular scaffold of bis-(2-methyl-3-amino-1,2,4-triazolyl)-furoxan (compound 1). The incorporation of the nitroform anion significantly enhances the energetic performance while maintaining moderate stability. Single-crystal X-ray diffraction analysis revealed that compound 2 crystallizes in the orthorhombic space group P2₁2₁2₁ with a density of 1.712 g·cm⁻³. Although its crystal packing adopts a less optimal zigzag-type mixed stacking mode and exhibits uneven electrostatic potential distribution, an extensive intramolecular hydrogen-bonding network contributes to its structural stability, as evidenced by a thermal decomposition temperature of 141 °C and impact sensitivity of 17 J. Detonation parameters calculated using EXPLO5 software demonstrate superior performance (detonation velocity = 8271 m·s⁻¹, detonation pressure = 26.9 GPa) compared to TNT and close proximity to RDX, coupled with markedly improved mechanical stability over both RDX and HMX. Hirshfeld surface and electrostatic potential analyses further elucidate the relationship between molecular structure and sensitivity, highlighting the critical role of hydrogen bonding in moderating mechanical sensitivity despite high energy content. These results underscore the potential of nitroform functionalization for designing advanced energetic materials with balanced performance and safety. Full article

Innovative energy storage technologies in the energetic materials field represent a critical frontier in energy research. Consequently, we developed a performance regulation strategy based on tetrazolyl high-energy-density energy storage molecular systems and theoretically assessed their energetic properties and safety profiles. The findings reveal that substituent characteristics profoundly affect the performances of these energy storage molecular systems. The molecule systems ((1-amino-1H-tetrazol-5-yl)azanediyl)bis(1H-tetrazole-5,1-diyl) dinitrate, ((1-azido-1H-tetrazol-5-yl)azanediyl)bis(1H-tetrazole-5,1-diyl) dinitrate, ((1-nitro-1H-tetrazol-5-yl)azanediyl)bis(1H-tetrazole-5,1-diyl) dinitrate, and especially ((1-azido-1H-tetrazol-5-yl)azanediyl)bis(1H-tetrazole-5,1-diyl) dinitrate, exhibit exceptional performances, including high density, high heat of formation, high detonation velocity and pressure, zero oxygen balance, and low impact sensitivity, qualifying them as high-energy-density and low-sensitivity candidates. This work offers novel pathways for advancing energy storage technologies in energetic materials field. Full article

In high-temperature testing scenarios that rely on contact, fine-wire thermocouples demonstrate commendable dynamic performance. Nonetheless, their thermal inertia leads to notable dynamic nonlinear inaccuracies, including response delays and amplitude reduction. To mitigate these challenges, a novel dynamic error correction approach is introduced, which combines a Continuous Restricted Boltzmann Machine, Deep Belief Network, and Physics-Informed Neural Network (CDBN-PINN). The unique heat transfer properties of the thermocouple’s bimetallic structure are represented through an Inverse Heat Conduction Equation (IHCP). An analysis is conducted to explore the connection between the analytical solution’s ill-posed nature and the thermocouple’s dynamic errors. The transient temperature response’s nonlinear characteristics are captured using CRBM-DBN. To maintain physical validity and minimize noise amplification, filtered kernel regularization is applied as a constraint within the PINN framework. This approach was tested and confirmed through laser pulse calibration on thermocouples with butt-welded and ball-welded configurations of 0.25 mm and 0.38 mm. Findings reveal that the proposed method achieved a peak relative error of merely 0.83%, superior to Tikhonov regularization by −2.2%, Wiener deconvolution by 20.40%, FBPINNs by 1.40%, and the ablation technique by 2.05%. In detonation tests, the corrected temperature peak reached 1045.7 °C, with the relative error decreasing from 77.7% to 5.1%. Additionally, this method improves response times, with the rise time in laser calibration enhanced by up to 31 ms and in explosion testing by 26 ms. By merging physical constraints with data-driven methodologies, this technique successfully corrected dynamic errors even with limited sample sizes. Full article

Blast damage to structural members poses serious risks to both buildings and people, making it important to understand how these elements behave under extreme loads. Columns in reinforced concrete (RC) structures are especially critical, as their sudden failure can trigger progressive collapse, unlike beams or slabs that have more redundancy. This state-of-the-art review brings together the current knowledge of the blast response of RC columns, focusing on their failure patterns, dynamic behavior, and key loading mechanisms. The studies covered include experiments, high-fidelity numerical simulations, emerging machine learning approaches, and analytical models for columns of different shapes (square, rectangular, circular) and strengthening methods, such as fiber reinforcement, steel-concrete composite confinement, and advanced retrofitting. Composite columns are also reviewed to compare their hybrid confinement and energy-absorption advantages over conventional RC members. Over forty specific studies on RC columns were analyzed, comparing the results based on geometry, reinforcement detailing, materials, and blast conditions. Both near-field and contact detonations were examined, along with factors like axial load, standoff distance, and confinement. This review shows that RC columns respond very differently to blasts depending on their shape and reinforcement. Square, rectangular, and circular sections fail in distinct ways. Use of ultra-high-performance concrete, steel fibers, steel-concrete composite, and fiber-reinforced polymer retrofits greatly improves peak and residual load capacity. Ultra-high-performance concrete can retain a significantly higher fraction of axial load (often >70%) after strong blasts, compared to ~40% in conventional high-strength RC under similar conditions. Larger sections, closer stirrups, higher transverse reinforcement, and good confinement reduce spalling, shear failure, and mid-height displacement. Fiber-reinforced polymer and steel-fiber wraps typically improve residual strength by 10–15%, while composite columns with steel cores remain stiff and absorb more energy post-blast. Advanced finite element simulations and machine learning models now predict displacements, damage, and residual capacity more accurately than older methods. However, gaps remain. Current design codes of practice simplify blast loads and often do not account for localized damage, near-field effects, complex boundary conditions, or pre-existing structural weaknesses. Further research is needed on cost-effective, durable, and practical retrofitting strategies using advanced materials. This review stands apart from conventional literature reviews by combining experimental results, numerical analysis, and data-driven insights. It offers a clear, quantitative, and comparative view of RC column behavior under blast loading, identifies key knowledge gaps, and points the way for future design improvements. Full article

Achieving a balance of good thermal stability, high performance, and appropriate sensitivity in materials remains a primary research goal in energetic materials. In this study, a series of dinitrimine-functionalized tris-1,3,4-oxadiazole-based energetic compounds was synthesized. Dinitroimmine 5 was found to possess favorable thermal stability (T_d = 180 °C), superior mechanical sensitivity (IS = 25 J, FS = 240 N), and good detonation velocity (v_D = 8372 m s⁻¹). These results suggest that this polyheterocyclic backbone structure facilitates the synthesis of high-performance energetic compounds with application potentials. Full article

The growing demand for safe and reliable weaponry has heightened performance requirements for explosives. Cocrystal systems, offering a balance between high energy density and safety, have become key targets in advanced energetic material research. However, the influence of molar ratios and crystal facets on thermal sensitivity, mechanical strength, and detonation properties remains underexplored. This study investigates cocrystals of hexanitrohexaazaisowurtzitane (CL-20) and 1,1-diamino-2,2-dinitroethylene (FOX-7) with molar ratios of 3:1, 5:1, and 8:1 on the (1 0 1) crystal facet, using the Forcite module in Materials Studio. Comparative analysis with (0 1 1) facet and pure explosives revealed that the 5:1 cocrystal achieved the highest cohesive energy density (0.773 kJ/cm³) and theoretical crystal density (1.953 g/cm³), driven by strong electrostatic and non-bonded interactions—indicating superior detonation performance. In contrast, the 3:1 cocrystal displayed optimal mechanical strength, with an elastic modulus of 8.562 GPa and shear modulus of 3.365 GPa, suitable for practical applications. The results suggest increasing CL-20 content enhances energy performance up to a point, beyond which structural loosening occurs (8:1 ratio) due to steric hindrance weakening van der Waals forces. This work clarifies how molar ratio regulates the influence between sensitivity, strength, and energy, providing guidance for designing application-specific high-energy cocrystals. Full article