The underwater explosion bubbles expand and contract several times until it runs out of energy, during the pulsations, the mutual conversion of energy occurs. At present, there is insufficient attention paid to multiple pulsations characteristics and energy conversion of underwater explosion bubbles. In this paper, the underwater explosion tests of 20, 40, and 60 g RS211 charges were carried out, and the evolution process of the bubbles multiple pulsations were photographed with a high-speed camera, then pulsation period and maximum radius of the bubbles were obtained after intelligent processing. On this basis, the theoretical analysis was conducted on the conversion mechanism of the potential energy, internal energy during the multiple pulsations. The results show that: (1) the residual energy rate of the second bubble pulsation relative to the first bubble pulsation was 0.31; (2) the proportion of internal energy of the bubbles to total energy is 5.4%−6.6%, so the internal energy could be ignored, and energy of the bubbles could be represented by the potential energy in the engineering application.

The explosion near-field is the core zone of munition-induced damage, involving the coupled load effect of intense shock waves and detonation products. Currently, the mechanical response and energy conversion mechanisms of expansion tube structures (ETS) under such extreme loading conditions remain unclear. In this study, ETS is adopted as a representative energy-absorbing structure to investigate its energy conversion behavior under the coupled action of near-field shock waves and detonation products. Based on the experimental verification, numerical simulation methods were employed to analyze the characteristics of near-field blast loading and the dynamic response of ETS. Furthermore, a theoretical prediction formula for near-field blast loading was established, and a theoretical model for predicting energy conversion efficiency was developed based on the strong-shock assumption. The results show that the energy conversion efficiency decreases significantly with increasing scaled distance. The energy conversion efficiency drops to below 10% when the scaled distance exceeds 0.80 m/kg^1/3. Moreover, the energy conversion efficiency exhibits a strong positive correlation with the specific impulse of the reflected wave, indicating that specific impulse is a key factor determining energy transfer. This work elucidates the intrinsic mechanism of energy conversion in ETS under near-field coupled loading. The proposed theoretical model provides a robust foundation for the design and performance evaluation of near-field protective structures.

To address the optimization design problem of the bursting performance of reverse-arched bursting discs (RABDs), a hierarchical Kriging (H-Kriging) surrogate model was constructed based on both high- and low-fidelity finite element analysis results. This model enables the rapid prediction of the burst pressure of RABDs, facilitating the development of a mathematical model for performance optimization and structural improvement. The results show that the H-Kriging surrogate model relating burst pressure to structural parameters based on high- and low-fidelity finite element models can significantly reduce computational cost while accurately predicting the burst pressure of RABDs. For the initial structural design scheme of RABDs, optimization was carried out using a genetic algorithm, with the optimized design accounting for manufacturing tolerance in disc thickness. This resulted in a 58.8% reduction in burst pressure fluctuation, significantly reducing the sensitivity of burst pressure to thickness manufacturing errors and providing valuable engineering reference.

Explosion prevention and mitigation technologies for hydrogen-methane gas mixtures represent a critical research area for ensuring the safe application of hydrogen energy. This study systematically investigates the inhibition mechanism of potassium bicarbonate (KHCO₃)-containing fine water mist on methane-hydrogen premixed deflagration using a combined approach of experiment and numerical simulation. The results indicate that KHCO₃-containing fine water mist exhibits a significant inhibitory effect on methane-hydrogen premixed deflagration, with its suppression performance positively correlated to the KHCO₃ mass fraction. Taking the condition of H₂ volume fraction of 10% as an example, 11% KHCO₃ addition resulted in reductions of the maximum explosion pressure and the average pressure rise rate by 34.64% and 44.57%, respectively. The laminar burning velocity was reduced by up to 66.43%. KHCO₃ contributes to suppression through both physical and chemical mechanisms. Physically, droplet phase change (evaporation) absorbs heat and the generated steam dilutes the fuel mixture, thereby lowering the flame temperature and reducing reactant concentrations. Chemically, the decomposition of KHCO₃ generates potassium compounds, which undergo the KOH→K→KOH recombination cycle to scavenge key radicals (·H, ·O, ·OH). This process competes with chain-branching reactions and interrupts the combustion chain reactions. Furthermore, the suppression process is governed by a competition between inhibitory and promotional effects. At high hydrogen blending ratios and high mass fractions of KHCO₃, the physical evaporation efficiency becomes a bottleneck that constrains the chemical inhibition, leading to a saturation of the overall suppression efficiency. Nevertheless, a significant inhibitory effect is still maintained.

The physical properties of iron under extreme high-pressure and high-temperature conditions are crucial for understanding the internal structure and evolutionary processes of Earth and terrestrial planets. To characterize the dynamic behavior of iron under the extreme conditions inside super-Earths, we combine first-principles molecular dynamics simulations with experimentally measured high-pressure melting curves to construct an embedded-atom potential applicable across ultra-high pressures and temperatures. This potential is fitted to multiple properties of the body-centered cubic (BCC), hexagonal close-packed (HCP), and liquid phases over 400 GPa to 1 TPa and 6000 to 10000 K, including the elastic constants of the solid phases, the radial distribution functions of the liquid, and experimentally determined melting data. We systematically validate the potential across different pressure-temperature conditions and found that it accurately reproduces the pressure and temperature dependence of solid elastic constants, and matches liquid radial distribution functions at three representative pressure-temperature conditions. Moreover, it predicts melting curves that lie within experimental uncertainties and agree well with previous first-principles simulations. Thermodynamic calculations based on this potential further show that the HCP phase remains thermodynamically stable between 400 GPa and 1 TPa, while the BCC phase is metastable. This potential provides a reliable atomistic tool for large-scale simulations of nucleation, crystallization, and solid-liquid coexistence in the cores of super-Earths. Moreover, the potential and associated dataset lay the groundwork for future extensions to multicomponent Fe alloys and their properties under ultra-high-pressure conditions.

In order to accurately regulate the damage effect of slit pack blasting on the backfill of the quarry in deep mines, this study focuses on the damage control mechanism of the peripheral hole spacing (500, 600, 700, 800 mm). Based on the theory of elastic fluctuation and the dynamic propagation characteristics of shock waves in rocky media, the diffusion mechanism of the stress wave under the action of multi-media in the constrained orientation during slit packet blasting is established. Combined with the strong correlation between brittle concrete materials and the damage evolution of the backfill, the cross-media equivalence calibration framework of the Riedel-Hiermaier-Thoma (RHT) intrinsic model is established. Based on the numerical simulation software ANSYS/LS-DYNA, we constructed a multi-media dynamic coupling numerical model of “filling body-mineral body-cutting slit package”, arranged observation points at the junction of filling body-mineral body, and conducted a combined analysis of the peak stress change, the change of the blast vibration velocity, and the damage evolution of the filling body at the observation points. Then, based on the blasting test of the approach and return stage of the neighboring filling body in Jinchuan Three Mining Area, the blasting test of conventional packs, slit packs and different peripheral hole spacing was conducted. The test shows that: slit pack blasting triggers gas-phase jet and strain-energy convergence effects in the unconfined direction, synchronously suppresses the stress and vibration peaks in the confined direction, and achieves directional attenuation of the blasting load on the neighboring filling body; the field test shows that, compared with the conventional charge, the slit pack significantly reduces the degree of damage of the backfill by more than 36%; the degree of blasting damage and the peripheral hole spacing show a negative correlation, and the damage suppression efficiency is improved with the increase of the spacing. The damage suppression efficiency is improved when the spacing increases.

Metallic hydrogen, with its properties including room-temperature superconductivity and quantum fluidity, is known as the holy grail of high-pressure physics. However, since atomic metallic hydrogen requires pressures about 500 GPa, it has not been realized in experiments since its conception in 1935. To take advantage of properties the properties of metallic hydrogen in the future, it will be crucial to obtain it at ambient pressure. Current approaches to obtaining metallic hydrogen at low pressures rely on the “chemical precompression” in hydrides to induce metallization of hydrogen at low pressures, essentially identifying superconducting hydrides that can host the properties of metallic hydrogen. However, these superconducting hydrides currently lack distinct structural features, complicating the search for metallic hydrogen hosts. Here, we identify metallic hydrogen ligand compounds with hydrogen as the ligands as potential hosts for properties of metallic hydrogen at low pressures. The metallization of the non-bonding orbitals of the hydrogen ligands is a key criterion for determining whether a metallic hydrogen ligand compound can host metallic hydrogen properties. This article summarizes the main behaviors of hydrogen at ambient pressure, focusing on hydrogen ligand compounds at ambient pressure. Then, using a simple model of a one-dimensional hydrogen atom chain, we analyzed the causes of non-bonding orbital metallization and the physical picture of reduced stability pressure. The orbital characteristics of metallic hydrogen ligand compounds are then analyzed, highlighting their rules of superconductivity, topological properties, and the electronic structure that enable metallization. The analysis of metallic hydrogen ligand compounds presented in this article not only provides important structural information for future exploration of metal hydride superconductors but also provides an important theoretical foundation for realizing the properties of metallic hydrogen at ambient pressure.

Ultra high static pressure processing technology holds promise for food sterilization, improving food quality, and extracting active ingredients. Traditional research typically assesses the analysis of the structure and function of organic matter under high static pressure after pressure release, capturing only irreversible changes occurring during compression. In-situ monitoring under pressure is rarely conducted. In-situ technology provides dynamic insights into sample behavior, offering a deeper understanding of its transformation process. Consequently, recent years have witnessed a surge in-situ studies performed under high pressure. This article reviews the advancement of high-pressure in-situ analysis technology and its application in high static pressure food processing. Key areas covered, include structural changes and phase transition intervals of protein folding and denaturation under high pressure, in-situ investigations into the mechanism of starch gelatinization, microbial in-situ monitoring and the challenges of in-situ technology in food processing.

In order to study the influence of plateau environment on emulsion explosive sensitized by different methods, three typical sensitization materials were selected to prepare emulsion explosive samples. The changes in microstructure and detonation performance of samples stored in simulated plateau environment (−20 ℃, about 0.05 MPa) were analyzed. The results showed that the low temperature and low pressure of plateau environment mainly affects the performance of explosives from the aspects of aggravating the stability of emulsion system and the distribution of hot spots. In the plateau environment, the crystallization degree of chemically sensitized explosives is lower than that of physically sensitized explosives but the hot spots change greatly, leading to a decrease in detonation performance. In the physical sensitization, the growth mode of expanded perlite explosive crystal is more complex, so it is easier to demulsify and crystallize, and the storage stability and detonation performance are significantly reduced. The degree of crystallization and detonation performance of resin microsphere explosive are relatively stable under low temperature and low pressure. In general, resin microspheres emulsion explosive has better adaptability to plateau.

Nitrogen is the main component of the Earth’s atmosphere, accounting for about 78% by volume. At room temperature and pressure, nitrogen is combined into stable diatomic molecules in the form of triple bonds (N≡N). Under the action of extreme high pressure, nitrogen can dissociate into a solid polynitrogen structure containing double bonds (N＝N) or even single bonds (N—N). Due to the huge energy difference between N≡N and N＝N or N—N, the transformation process is accompanied by huge energy release, so polynitrogen is a high energy density substance that attracts much attention. However, elemental polymerized nitrogen must be prepared in an environment above millions of atmospheric pressure (100 GPa) which is too harsh, greatly limiting the development and application of such materials. Interestingly, the introduction of metal elements can reduce the reaction barrier and provide chemical pressure, which can effectively reduce the synthetic pressure of polynitrogen and form a rich variety of polynitrogen configurations. This paper focuses on the research progress of main group metal nitriding compounds under high pressure, the physical mechanism of stabilities for metal nitrogen-rich compounds under high pressure, and puts forward the prospect of future design and preparation of new nitrogen-rich compounds.