We present a novel photonic Doppler velocimetry(PDV)design for laser-driven shock-wave experiments.This PDV design is intended to provide the capability of measuring the free-surface velocity of shocked opaque materia...We present a novel photonic Doppler velocimetry(PDV)design for laser-driven shock-wave experiments.This PDV design is intended to provide the capability of measuring the free-surface velocity of shocked opaque materials in the terapascal range.We present measurements of the free-surface velocity of gold for as long as∼2 ns from the shock breakout,at pressures of up to∼7 Mbar and a free-surface velocity of 7.3 km/s with an error of∼1.5%.Such laboratory pressure conditions are achieved predominantly at high-intensity laser facilities where the only velocity diagnostic is usually line-imaging velocity interferometry for any reflector.However,that diagnostic is limited by the lower dynamic range of the streak camera(at a temporal resolution relevant to laser shock experiments)to measure the free-surface velocity of opaque materials up to pressures of only∼1 Mbar.We expect the proposed PDV design to allow the free-surface velocity of opaque materials to be measured at much higher pressures.展开更多
Single-shot X-ray phase-contrast imaging is used to take high-resolution images of laser-driven strong shock waves.Employing a two-grating Talbot interferometer,we successfully acquire standard absorption,differential...Single-shot X-ray phase-contrast imaging is used to take high-resolution images of laser-driven strong shock waves.Employing a two-grating Talbot interferometer,we successfully acquire standard absorption,differential phase-contrast,and dark-field images of the shocked target.Good agreement is demonstrated between experimental data and the results of two-dimensional radiation hydrodynamics simulations of the laser-plasma interaction.The main sources of image noise are identified through a thorough assessment of the interferometer’s performance.The acquired images demonstrate that grating-based phase-contrast imaging is a powerful diagnostic tool for high-energy-density science.In addition,we make a novel attempt at using the dark-field image as a signal modality of Talbot interferometry to identify the microstructure of a foam target.展开更多
We present a numerical framework for simulating viscous compressible flows in the presence of solid particles with large size ratios.The volume-filtered Navier-Stokes equations are discretized using a class of high-or...We present a numerical framework for simulating viscous compressible flows in the presence of solid particles with large size ratios.The volume-filtered Navier-Stokes equations are discretized using a class of high-order low-dissipative finite difference operators with energy-preserving properties.No-slip,adiabatic boundary conditions are enforced at the surface of large particles(with diameters significantly larger than the local grid spacing)using a ghost-point immersed boundary method.Two-way coupling between the gas phase and small particles(with diameters proportional to the grid spacing)is accounted for through volumetric source terms for interphase momentum and energy exchange.A simple and efficient approach for collision detection between small and large particles is proposed.The framework is applied to simulations of planar shocks interacting with bidisperse distributions of particles with size ratios of approximately thirty.Particle dispersion and size segregation are reported and a simple analytical model for size segregation is proposed.展开更多
Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials,highlighting the need to investigate alternative ignition systems,such as laser-based techniques.Over the past decade...Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials,highlighting the need to investigate alternative ignition systems,such as laser-based techniques.Over the past decade,lasers have emerged as a promising solution,providing focused energy beams for controllable,efficient,and reliable ignition in the field of energetic materials.This study presents a comparative analysis of two state-of-the-art ignition approaches:direct laser ignition and laser-driven flyer ignition.Experiments were performed using a Neodymium-doped Yttrium Aluminum Garnet(Nd:YAG)laser at different energy beam levels to systematically evaluate ignition onset.In the direct laser ignition test setup,the laser beam was applied directly to the energetic tested material,while laserdriven flyer ignition utilized 40 and 100μm aluminum foils,propelled at velocities ranging from 300 to 1250 m/s.Comparative analysis with the Lawrence and Trott model substantiated the velocity data and provided insight into the ignition mechanisms.Experimental results indicate that the ignition time for the laser-driven flyer method was significantly shorter,with the pyrotechnic composition achieving complete combustion faster compared to direct laser ignition.Moreover,precise ignition thresholds were determined for both methods,providing critical parameters for optimizing ignition systems in energetic materials.This work elucidates the advantages and limitations of each technique while advancing next-generation ignition technology,enhancing the reliability and safety of propulsion systems.展开更多
As a multidisciplinary phenomenon,panel aeroelasticity in shock-dominated flow is featured by two primary interactions:Fluid-Structure Interactions(FSIs)and Shock-Boundary Layer Interactions(SBLIs).The former raises s...As a multidisciplinary phenomenon,panel aeroelasticity in shock-dominated flow is featured by two primary interactions:Fluid-Structure Interactions(FSIs)and Shock-Boundary Layer Interactions(SBLIs).The former raises structural concerns,and the latter is of aerodynamic interest.Thus,panel aeroelasticity in shock-dominated flow represents a vital topic for the development and optimization of supersonic vehicles and propulsion systems.This review systematically summarizes recent advances in the methodologies applied to capture structural and fluid dynamics,including theoretical models,numerical simulations,and wind tunnel experiments.The application of data-driven modal decomposition,an advanced technique to extract physically crucial features,on the topic is introduced.From the perspective of FSIs,the distinctive aeroelastic behaviors in shock-dominated flow,including hysteresis phenomena and nonlinear responses,are highlighted.From the perspective of SBLIs,the modifications in their spatial and temporal characteristics imposed by the aeroelastic responses are emphasized.Motivated by the interaction between the shock waves and structural response,different strategies have been proposed to implement aeroelastic suppression and shock control,which have the potential to enhance structural safety and aerodynamic performance in the next generation of high-speed flight vehicles.展开更多
The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,an...The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.展开更多
Laser-driven inertial confinement fusion(ICF)is an important experimental platform for high-energy-density physics research under extreme conditions.In ICF research,high-quality shock waves are key to fusion energy re...Laser-driven inertial confinement fusion(ICF)is an important experimental platform for high-energy-density physics research under extreme conditions.In ICF research,high-quality shock waves are key to fusion energy release.The velocity interferometer system for any reflector(VISAR)is the most important diagnostic technique for measuring quantities such as shock wave and particle velocities with high precision and high spatiotemporal resolution.This paper provides a detailed introduction to the various configurations of VISAR on 10 and 100 kJ-level laser facilities in China,including Line VISAR,Dual-Axis VISAR,Wide-Angle VISAR,and Compressed Ultrafast Photography-VISAR.Recent advances and applications of VISAR diagnostics at these laser facilities are presented,and the future trend of development of high-spatiotemporal-resolution velocity diagnostic technology is described.展开更多
Lead(Pb)is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses.Under shock-wave loading,its dynamic mechanical behavior comprises two key phenomena:pla...Lead(Pb)is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses.Under shock-wave loading,its dynamic mechanical behavior comprises two key phenomena:plastic deformation and shock-induced phase transitions.The underlying mechanisms of these processes are still poorly understood.Revealing these mechanisms remains challenging for experimental approaches.Non-equilibrium molecular dynamics(NEMD)simulations are an alternative theoretical tool for studying dynamic responses,as they capture atomic-scale mechanisms such as defect evolution and deformation pathways.However,due to the limited accuracy of empirical interatomic potentials,the reliability of previous NEMD studies has been questioned.Using our newly developed machine learning potential for Pb-Sn alloys,we revisited the microstructural evolution in response to shock loading under various shock orientations.The results reveal that shock loading along the[001]orientation of Pb exhibits a fast,reversible,and massive phase transition and stacking-fault evolution.The behavior of Pb differs from previous studies by the absence of twinning during plastic deformation.Loading along the[011]orientation leads to slow,irreversible plastic deformation,and a localized FCC-BCC phase transition in the Pitsch orientation relationship.This study provides crucial theoretical insights into the dynamic mechanical response of Pb,offering a theoretical input for understanding the microstructure-performance relationship under extreme conditions.展开更多
Recovered samples of Jilin H5 chondrite experimentally shocked to 12-133 GPa were studied to explore the behavior of opaque minerals under shock loading using SEM-EDS,Raman spectroscopy,and TIMA.The following results ...Recovered samples of Jilin H5 chondrite experimentally shocked to 12-133 GPa were studied to explore the behavior of opaque minerals under shock loading using SEM-EDS,Raman spectroscopy,and TIMA.The following results were obtained.Firstly,at pressures lower than 53GPa,the opaque minerals still keep the unmelted state,while at 78 GPa and higher,FeNi metal and troilite form eutectic intergrowths occurring as disorderly fine veinlets filling the shock-induced fractures in silicate minerals.Secondly,single kamacite grains still maintain their contour at 12 GPa,but a part of brittle troilite grains was fragmented and squeezed into the shock-induced fractures within kamacite grains.At53 and 133 GPa,many more troilite fragments are poured in the kamacite interior to form disordered hybrid aggregates or to form squiggly strips,respectively.Similar phenomena are observed within single troilite grains,but the mineral squeezed into troilite grains is kamacite.Thirdly,chromite is a hard and refractory oxide mineral.When the shock pressure rises step by step from 12 to 133 GPa,the shock effect of chromite is only fragmentation.Its grain size decreases from tens of um at 53 GPa to a few um at 133 GPa.And,fourthly,native copper exhibits distinct redistribution behavior at high temperature.In Jilin samples shock-loaded to 12 GPa,copper initially located at troilite-kamacite interfaces partially transferred into small troilite grains containing fine FeNi particles.At 53 and 133 GPa,native copper preferentially transferred into larger troilite grains containing more particles of eutectic FeNi metal.展开更多
Aluminum nanoparticles,owing to their high energy density and excellent reactivity,are widely used to enhance the energy release efficiency of explosives.In this study,reactive molecular dynamics simulations were empl...Aluminum nanoparticles,owing to their high energy density and excellent reactivity,are widely used to enhance the energy release efficiency of explosives.In this study,reactive molecular dynamics simulations were employed to systematically investigate the hotspot evolution and reaction kinetics of aluminum nanoparticles under shock loading.The results show that hotspots predominantly form and evolve along the oxide layer interface,exhibiting a typical"hot shell-cold core"structure.A thicker oxide layer significantly delays the heating and reaction initiation of the aluminum core,with reversible crystal structure transformations observed inside the core.Larger particles facilitate heat accumulation and promote sustained reactions.As the oxide layer thickness increases,the reaction mechanism of aluminum nanoparticles transitions from melting-diffusion and micro-explosion oxidation to an oxidation-diffusion dominated process.A dense nitrogen-containing reaction layer forms on the surface,which suppresses the later-stage reaction.A nonlinear reaction kinetics model based on bond statistics reveals that particles with a thin oxide layer exhibit rapid reaction saturation and are insensitive to shock velocity.Particles with intermediate oxide thickness exhibit a reaction behavior that gradually slows down over time,while those with a thick oxide layer can exhibit accelerated reactions under high-velocity shocks due to enhanced diffusion.Small particles show significantly increased reaction rates at high velocities,whereas large particles tend to slow down due to the thickening of the surface reaction layer.The oxide layer thickness,particle size,and shock velocity exhibit complex competitive and synergistic effects that jointly regulate the initiation,rate,and evolution of aluminum nanoparticle reactions.展开更多
Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens un...Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.展开更多
Quasi-hemispherical magnetized collisionless shocks have been generated at the SG-II laser facility through the interaction between a laserproduced supersonic plasma flow and a magnetized ambient plasma,exhibiting an ...Quasi-hemispherical magnetized collisionless shocks have been generated at the SG-II laser facility through the interaction between a laserproduced supersonic plasma flow and a magnetized ambient plasma,exhibiting an angular asymmetric shock profile accompanied by asymmetric ion acceleration.We have conducted test particle simulations using the electromagnetic fields derived from 2D MHD simulations to investigate the asymmetry of ion acceleration.The simulations reproduce the angular asymmetry of the shock and the ion acceleration observed in experiments.The results indicate that shock drift acceleration is the primary mechanism for ion energization in the present quasiperpendicular magnetized shock.The asymmetric shock structure caused by nonuniform ambient plasma forms an asymmetric accelerated electric field,ultimately leading to angular asymmetric ion acceleration,which is consistent with space observations and our experimental results.Our study provides a plausible explanation for the discrepancies reported in previous ion acceleration experiments,and could contribute to understanding of the collisionless shock acceleration.展开更多
For hypersonic air-breathing vehicles,the V-shaped leading edges(VSLEs)of supersonic combustion ramjet(scramjet)inlets experience complex shock interactions and intense aerodynamic loads.This paper provides a comprehe...For hypersonic air-breathing vehicles,the V-shaped leading edges(VSLEs)of supersonic combustion ramjet(scramjet)inlets experience complex shock interactions and intense aerodynamic loads.This paper provides a comprehensive review of flow characteristics at the crotch of VSLEs,with particular focus on the transition of shock interaction types and the variation of wall heat flux under different freestream Mach numbers and geometric configurations.The mechanisms governing shock transition,unsteady oscillations,hysteresis,and three-dimensional effects in VSLE flows are first examined.Subsequently,thermal protection strategies aimed at mitigating extreme heating loads are reviewed,emphasizing their relevance to practical engineering applications.Special attention is given to recent studies addressing thermochemical nonequilibrium effects on VSLE shock interactions,and the limitations of current research are critically assessed.Finally,perspectives for future investigations into hypersonic VSLE shock interactions are outlined,highlighting opportunities for advancing design and thermal management strategies.展开更多
Shock tunnels are indispensable facilities for hypersonic aerodynamic experimentation.Within these systems,the diaphragm plays a pivotal role,as its rupture process critically influences shock wave generation quality,...Shock tunnels are indispensable facilities for hypersonic aerodynamic experimentation.Within these systems,the diaphragm plays a pivotal role,as its rupture process critically influences shock wave generation quality,experimental repeatability,and facility reliability.A thorough understanding of diaphragm rupture dynamics is therefore essential for optimizing shock tunnel design,improving experimental accuracy,and ensuring operational safety.To address the complex challenge of fully coupled multiphysics analysis in high-pressure-ratio shock tunnels,this study introduces a high-fidelity,three-dimensional,fully coupled Fluid-Structure Interaction(FSI)simulation framework.This framework seamlessly integrates the Dual Conservation Element and Solution Element(Dual-CESE)method,the Immersed Boundary Method(IBM),and the JohnsonCook(J-C)material constitutive and failure model.The combined approach enables synchronized simulation and analysis of the entire diaphragm rupture sequence—including pre-deformation,crack initiation and propagation,and fully developed petaling deformation—alongside the formation and evolution of the associated supersonic flow field.The simulation results show strong agreement with experimental observations,with the post-rupture geometric morphology accurately replicated and a shock wave velocity deviation of only 2.55%from experimental measurements.The study uncovers the dynamic failure mechanisms,revealing that nonlinear pressure loading initiates cracking within the diaphragm.It further elucidates how the nonlinearly coupled interactions between petaling dynamics and fracture morphology directly impact shock wave formation and evolution.This computational framework provides a novel and robust methodology for advancing shock tunnel design and conducting comprehensive reliability assessments.展开更多
To investigate the fracture initiation and propagation behavior of fractures in tight sandstone under the supercritical CO_(2)(SCCO_(2))shock fracturing,laboratory fracturing experiments were conducted using a true-tr...To investigate the fracture initiation and propagation behavior of fractures in tight sandstone under the supercritical CO_(2)(SCCO_(2))shock fracturing,laboratory fracturing experiments were conducted using a true-triaxial-like SCCO_(2)shock fracturing system.Computed tomography(CT)scanning and three-dimensional fracture reconstruction were employed to elucidate the effects of shock pressure,pore pressure,and in-situ stress on fracture characteristics.In addition,nuclear magnetic resonance(NMR)transverse relaxation time spectra were used to assess the internal damage induced by SCCO_(2)shock fracturing.The results indicate that,compared with conventional hydraulic fracturing and SCCO_(2)quasi-static fracturing,SCCO_(2)shock fracturing facilitates multidirectional fracture initiation and the formation of complex fracture networks.Increasing shock pressure more readily activates bedding-plane weaknesses,with main and subsidiary fractures interweaving into a dense fracture network.Under the same impulse intensity,elevated pore pressure reduces the effective normal stress and alters stress-wave scattering paths,thereby inducing more branch fractures and enhancing fracture complexity.An increase in differential in-situ stress promotes fracture propagation along the direction of the maximum principal stress,reduces branching,and simplifies fracture morphology.With increasing SCCO_(2)shock pressure,pore volume and connectivity generally increase:small-to-medium pores primarily respond through increased number and enhanced connectivity;when the shock pressure rises to 40-45 MPa,crack coalescence generates larger pores and fissures,which play a dominant role in improving flow pathways and effective storage space,ultimately forming a multiscale pore-fracture network.展开更多
Tellurene,a chiral chain semiconductor with a narrow bandgap and exceptional strain sensitivity,emerges as a pivotal material for tailoring electronic and optoelectronic properties via strain engineering.This study el...Tellurene,a chiral chain semiconductor with a narrow bandgap and exceptional strain sensitivity,emerges as a pivotal material for tailoring electronic and optoelectronic properties via strain engineering.This study elucidates the fundamental mechanisms of ultrafast laser shock imprinting(LSI)in two-dimensional tellurium(Te),establishing a direct relationship between strain field orientation,mold topology,and anisotropic structural evolution.This is the first demonstration of ultrafast LSI on chiral chain Te unveiling orientation-sensitive dislocation networks.By applying controlled strain fields parallel or transverse to Te’s helical chains,we uncover two distinct deformation regimes.Strain aligned parallel to the chain’s direction induces gliding and rotation governed by weak interchain interactions,preserving covalent intrachain bonds and vibrational modes.In contrast,transverse strain drives shear-mediated multimodal deformations—tensile stretching,compression,and bending—resulting in significant lattice distortions and electronic property modulation.We discovered the critical role of mold topology on deformation:sharp-edged gratings generate localized shear forces surpassing those from homogeneous strain fields via smooth CD molds,triggering dislocation tangle formation,lattice reorientation,and inhomogeneous plastic deformation.Asymmetrical strain configurations enable localized structural transformations while retaining single-crystal integrity in adjacent regions—a balance essential for functional device integration.These insights position LSI as a precision tool for nanoscale strain engineering,capable of sculpting 2D material morphologies without compromising crystallinity.By bridging ultrafast mechanics with chiral chain material science,this work advances the design of strain-tunable devices for next-generation electronics and optoelectronics,while establishing a universal framework for manipulating anisotropic 2D systems under extreme strain rates.This work discovered crystallographic orientation-dependent deformation mechanisms in 2D Te,linking parallel strain to chain gliding and transverse strain to shear-driven multimodal distortion.It demonstrates mold geometry as a critical lever for strain localization and dislocation dynamics,with sharp-edged gratings enabling unprecedented control over lattice reorientation.Crucially,the identification of strain field conditions that reconcile severe plastic deformation with single-crystal retention offers a pathway to functional nanostructure fabrication,redefining LSI’s potential in ultrafast strain engineering of chiral chain materials.展开更多
Hemorrhagic shock(HS)is a leading cause of death worldwide,particularly within the first 24 h post-injury.Current treatments are limited,especially in low-resource settings.Therapeutic hypothermia(TH)offers potential ...Hemorrhagic shock(HS)is a leading cause of death worldwide,particularly within the first 24 h post-injury.Current treatments are limited,especially in low-resource settings.Therapeutic hypothermia(TH)offers potential benefits by reducing metabolic demands and protecting organs,but its application in HS is challenged by cooling difficulties and side effects.This study introduces a novel nasal gel formulation of N6-cyclohexyladenosine(CHA),an adenosine A1 receptor agonist,designed to enhance brain delivery while minimizing peripheral side effects.In a mouse model of HS,administration of CHA nasal gel significantly improved survival rates,reduced metabolic rates,and protected major organs without worsening coagulopathy.Metabolomics analysis revealed a shift towards fatty acid oxidation and increased antioxidant capacity.These findings demonstrate that CHA nasal gel effectively induces TH,offering a safe and innovative treatment strategy for HS,particularly in resource-limited environments.展开更多
Stator vanes especially vane suction sides of transonic turbines are subjected to high frequency excitation forces under many circumstances,and thus are exposed to the risk of high cycle fatigue.Therefore,it is necess...Stator vanes especially vane suction sides of transonic turbines are subjected to high frequency excitation forces under many circumstances,and thus are exposed to the risk of high cycle fatigue.Therefore,it is necessary to reveal the flow mechanism of this kind of excitations for potential prevention measures.In this paper,the traveling shock phenomenon in the transonic turbine stator/rotor gap is observed and the concept of‘Inter-Row Traveling Shock(IRTS)'is proposed through the unsteady Reynolds-Averaged Navier-Stokes(RANS)simulation of a typical highlyloaded transonic turbine stage.The characteristics of an IRTS were described and summarized in aspects of unsteady shock wave system,aerodynamic characteristics and motion.The probable forming mechanism of an IRTS was explained through a theoretical model and it was validated through correct prediction of the flow state parameter change across the IRTS.Since IRTSs would strike onto vane suction sides,the pressure oscillation dynamic modes on vane suction side corresponding to the characteristic frequencies associated with IRTS were extracted through Dynamic Mode Decomposition(DMD),from which the way and extent of the IRTS influences on vane aerodynamic excitation were revealed and evaluated.Over 82%pressure oscillation energy on vane suction side could be brought by the IRTS sweeping along with blade rotation.展开更多
Laser powder bed fusion(LPBF)is an attractive additive manufacturing technology for preparing high-performance high-entropy alloys(HEAs)engineering components.Unfortunately,the existence of inherent thermal residual s...Laser powder bed fusion(LPBF)is an attractive additive manufacturing technology for preparing high-performance high-entropy alloys(HEAs)engineering components.Unfortunately,the existence of inherent thermal residual stress and non-equilibrium microstructures in the additively manufactured components results in unsatisfactory mechanical properties.Herein,we propose a novel strengthening strategy,namely deep cryogenic treatment(DCT)followed by laser shock peening(LSP),to tailor the microstructures and enhance performances of an LPBF additively manufactured metastable HEA.The post-treatment effects of DCT+LSP on the LPBF-fabricated Fe_(50)Mn_(30)Co_(10)Cr_(10)HEA are evaluated in terms of microstructural modifications,residual stress,and microhardness redistribution,as well as tensile properties.Results indicate that a gradient heterogeneous structure is formed on the as-built sample surface,featuring gradient variations in grain size,martensitic phase content,and dislocation density,due to the grain refinement and martensitic phase transformation under DCT+LSP.The initial tensile residual stress on the surface is fully transformed into compressive stress,achieving a peak of-289 MPa,and the surface microhardness attains a maximum of 380.8 HV.The various strengthening mechanisms of gradient heterogeneous structures,as well as the multiple effects of heterodeformation-induced(HDI)hardening,transformation-induced plasticity(TRIP),and twinning-induced plasticity(TWIP),are responsible for achieving strength-ductility synergy.This work provides a practical pathway and valuable scientific insights for enhancing the mechanical behaviors of additively manufactured metastable HEAs via microstructural engineering.展开更多
It is well known that aluminum and copper exhibit structural phase transformations in quasi-static and dynamic measurements,including shock wave loading.However,the dependence of phase transformations in a wide range ...It is well known that aluminum and copper exhibit structural phase transformations in quasi-static and dynamic measurements,including shock wave loading.However,the dependence of phase transformations in a wide range of crystallographic directions of shock loading has not been revealed.In this work,we calculated the shock Hugoniot for aluminum and copper in different crystallographic directions([100],[110],[111],[112],[102],[114],[123],[134],[221]and[401])of shock compression using molecular dynamics(MD)simulations.The results showed a high pressure(>160 GPa for Cu and>40 GPa for Al)of the FCC-to-BCC transition.In copper,different characteristics of the phase transition are observed depending on the loading direction with the[100]compression direction being the weakest.The FCC-to-BCC transition for copper is in the range of 150–220 GPa,which is consistent with the existing experimental data.Due to the high transition pressure,the BCC phase transition in copper competes with melting.In aluminum,the FCC-to-BCC transition is observed for all studied directions at pressures between 40 and 50 GPa far beyond the melting.In all considered cases we observe the coexistence of HCP and BCC phases during the FCC-to-BCC transition,which is consistent with the experimental data and atomistic calculations;this HCP phase forms in the course of accompanying plastic deformation with dislocation activity in the parent FCC phase.The plasticity incipience is also anisotropic in bothmetals,which is due to the difference in the projections of stress on the slip plane for different orientations of the FCC crystal.MD modeling results demonstrate a strong dependence of the FCC-to-BCC transition on the crystallographic direction,in which the material is loaded in the copper crystals.However,MD simulations data can only be obtained for specific points in the stereographic direction space;therefore,for more comprehensive understanding of the phase transition process,a feed-forward neural network was trained using MD modeling data.The trained machine learning model allowed us to construct continuous stereographic maps of phase transitions as a function of stress in the shock-compressed state of metal.Due to appearance and growth of multiple centers of new phase,the FCC-to-BCC transition leads to formation of a polycrystalline structure from the parent single crystal.展开更多
文摘We present a novel photonic Doppler velocimetry(PDV)design for laser-driven shock-wave experiments.This PDV design is intended to provide the capability of measuring the free-surface velocity of shocked opaque materials in the terapascal range.We present measurements of the free-surface velocity of gold for as long as∼2 ns from the shock breakout,at pressures of up to∼7 Mbar and a free-surface velocity of 7.3 km/s with an error of∼1.5%.Such laboratory pressure conditions are achieved predominantly at high-intensity laser facilities where the only velocity diagnostic is usually line-imaging velocity interferometry for any reflector.However,that diagnostic is limited by the lower dynamic range of the streak camera(at a temporal resolution relevant to laser shock experiments)to measure the free-surface velocity of opaque materials up to pressures of only∼1 Mbar.We expect the proposed PDV design to allow the free-surface velocity of opaque materials to be measured at much higher pressures.
基金funded by the Deutsche Forschungsgemeinschaft(DFG)under Grant No.452935060(“Einzelschuss Rontgen-Phasenkonstrast Abbildung von dichten Plasmen,”https://gepris.dfg.de/gepris/projekt/452935060)supported by Laserlab-Europe with GrantNo.PID20536supported by the Alexander von Humboldt Foundation.
文摘Single-shot X-ray phase-contrast imaging is used to take high-resolution images of laser-driven strong shock waves.Employing a two-grating Talbot interferometer,we successfully acquire standard absorption,differential phase-contrast,and dark-field images of the shocked target.Good agreement is demonstrated between experimental data and the results of two-dimensional radiation hydrodynamics simulations of the laser-plasma interaction.The main sources of image noise are identified through a thorough assessment of the interferometer’s performance.The acquired images demonstrate that grating-based phase-contrast imaging is a powerful diagnostic tool for high-energy-density science.In addition,we make a novel attempt at using the dark-field image as a signal modality of Talbot interferometry to identify the microstructure of a foam target.
基金This work used Expanse systems at UCSD through an allocation[PHY240089]from the Advanced Cyberinfrastructure Coordination Ecosystem:Services&Support(ACCESS)programsupported by U.S.National Science Foundation(Grant Nos.2138259,2138286,2138307,2137603 and 2138296).
文摘We present a numerical framework for simulating viscous compressible flows in the presence of solid particles with large size ratios.The volume-filtered Navier-Stokes equations are discretized using a class of high-order low-dissipative finite difference operators with energy-preserving properties.No-slip,adiabatic boundary conditions are enforced at the surface of large particles(with diameters significantly larger than the local grid spacing)using a ghost-point immersed boundary method.Two-way coupling between the gas phase and small particles(with diameters proportional to the grid spacing)is accounted for through volumetric source terms for interphase momentum and energy exchange.A simple and efficient approach for collision detection between small and large particles is proposed.The framework is applied to simulations of planar shocks interacting with bidisperse distributions of particles with size ratios of approximately thirty.Particle dispersion and size segregation are reported and a simple analytical model for size segregation is proposed.
文摘Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials,highlighting the need to investigate alternative ignition systems,such as laser-based techniques.Over the past decade,lasers have emerged as a promising solution,providing focused energy beams for controllable,efficient,and reliable ignition in the field of energetic materials.This study presents a comparative analysis of two state-of-the-art ignition approaches:direct laser ignition and laser-driven flyer ignition.Experiments were performed using a Neodymium-doped Yttrium Aluminum Garnet(Nd:YAG)laser at different energy beam levels to systematically evaluate ignition onset.In the direct laser ignition test setup,the laser beam was applied directly to the energetic tested material,while laserdriven flyer ignition utilized 40 and 100μm aluminum foils,propelled at velocities ranging from 300 to 1250 m/s.Comparative analysis with the Lawrence and Trott model substantiated the velocity data and provided insight into the ignition mechanisms.Experimental results indicate that the ignition time for the laser-driven flyer method was significantly shorter,with the pyrotechnic composition achieving complete combustion faster compared to direct laser ignition.Moreover,precise ignition thresholds were determined for both methods,providing critical parameters for optimizing ignition systems in energetic materials.This work elucidates the advantages and limitations of each technique while advancing next-generation ignition technology,enhancing the reliability and safety of propulsion systems.
基金supported by the National Natural Science Foundation of China(No.12372233)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.25GH01020005)the“111 Project”of China(No.B17037)。
文摘As a multidisciplinary phenomenon,panel aeroelasticity in shock-dominated flow is featured by two primary interactions:Fluid-Structure Interactions(FSIs)and Shock-Boundary Layer Interactions(SBLIs).The former raises structural concerns,and the latter is of aerodynamic interest.Thus,panel aeroelasticity in shock-dominated flow represents a vital topic for the development and optimization of supersonic vehicles and propulsion systems.This review systematically summarizes recent advances in the methodologies applied to capture structural and fluid dynamics,including theoretical models,numerical simulations,and wind tunnel experiments.The application of data-driven modal decomposition,an advanced technique to extract physically crucial features,on the topic is introduced.From the perspective of FSIs,the distinctive aeroelastic behaviors in shock-dominated flow,including hysteresis phenomena and nonlinear responses,are highlighted.From the perspective of SBLIs,the modifications in their spatial and temporal characteristics imposed by the aeroelastic responses are emphasized.Motivated by the interaction between the shock waves and structural response,different strategies have been proposed to implement aeroelastic suppression and shock control,which have the potential to enhance structural safety and aerodynamic performance in the next generation of high-speed flight vehicles.
基金supported by the National Natural Science Foundation of China(Grant No.12172063).
文摘The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.
基金supported by the National Key Laboratory of Plasma Physics,Laser Fusion Research Center,China Academy of Engineering Physics under the National Natural Science Foundation of China(Grant Nos.12127810 and 12475242).
文摘Laser-driven inertial confinement fusion(ICF)is an important experimental platform for high-energy-density physics research under extreme conditions.In ICF research,high-quality shock waves are key to fusion energy release.The velocity interferometer system for any reflector(VISAR)is the most important diagnostic technique for measuring quantities such as shock wave and particle velocities with high precision and high spatiotemporal resolution.This paper provides a detailed introduction to the various configurations of VISAR on 10 and 100 kJ-level laser facilities in China,including Line VISAR,Dual-Axis VISAR,Wide-Angle VISAR,and Compressed Ultrafast Photography-VISAR.Recent advances and applications of VISAR diagnostics at these laser facilities are presented,and the future trend of development of high-spatiotemporal-resolution velocity diagnostic technology is described.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1004300)the National Natural Science Foundation of China(Grant No.12404004)。
文摘Lead(Pb)is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses.Under shock-wave loading,its dynamic mechanical behavior comprises two key phenomena:plastic deformation and shock-induced phase transitions.The underlying mechanisms of these processes are still poorly understood.Revealing these mechanisms remains challenging for experimental approaches.Non-equilibrium molecular dynamics(NEMD)simulations are an alternative theoretical tool for studying dynamic responses,as they capture atomic-scale mechanisms such as defect evolution and deformation pathways.However,due to the limited accuracy of empirical interatomic potentials,the reliability of previous NEMD studies has been questioned.Using our newly developed machine learning potential for Pb-Sn alloys,we revisited the microstructural evolution in response to shock loading under various shock orientations.The results reveal that shock loading along the[001]orientation of Pb exhibits a fast,reversible,and massive phase transition and stacking-fault evolution.The behavior of Pb differs from previous studies by the absence of twinning during plastic deformation.Loading along the[011]orientation leads to slow,irreversible plastic deformation,and a localized FCC-BCC phase transition in the Pitsch orientation relationship.This study provides crucial theoretical insights into the dynamic mechanical response of Pb,offering a theoretical input for understanding the microstructure-performance relationship under extreme conditions.
基金Science and Technology Planning Project of Guangdong Province,2023B1212060048,Xiande Xie。
文摘Recovered samples of Jilin H5 chondrite experimentally shocked to 12-133 GPa were studied to explore the behavior of opaque minerals under shock loading using SEM-EDS,Raman spectroscopy,and TIMA.The following results were obtained.Firstly,at pressures lower than 53GPa,the opaque minerals still keep the unmelted state,while at 78 GPa and higher,FeNi metal and troilite form eutectic intergrowths occurring as disorderly fine veinlets filling the shock-induced fractures in silicate minerals.Secondly,single kamacite grains still maintain their contour at 12 GPa,but a part of brittle troilite grains was fragmented and squeezed into the shock-induced fractures within kamacite grains.At53 and 133 GPa,many more troilite fragments are poured in the kamacite interior to form disordered hybrid aggregates or to form squiggly strips,respectively.Similar phenomena are observed within single troilite grains,but the mineral squeezed into troilite grains is kamacite.Thirdly,chromite is a hard and refractory oxide mineral.When the shock pressure rises step by step from 12 to 133 GPa,the shock effect of chromite is only fragmentation.Its grain size decreases from tens of um at 53 GPa to a few um at 133 GPa.And,fourthly,native copper exhibits distinct redistribution behavior at high temperature.In Jilin samples shock-loaded to 12 GPa,copper initially located at troilite-kamacite interfaces partially transferred into small troilite grains containing fine FeNi particles.At 53 and 133 GPa,native copper preferentially transferred into larger troilite grains containing more particles of eutectic FeNi metal.
基金supported by the State Key Program of National Natural Science Foundation of China(No.12272051)the BIT Research and Innovation Promoting Project(No.2023YCXY17).
文摘Aluminum nanoparticles,owing to their high energy density and excellent reactivity,are widely used to enhance the energy release efficiency of explosives.In this study,reactive molecular dynamics simulations were employed to systematically investigate the hotspot evolution and reaction kinetics of aluminum nanoparticles under shock loading.The results show that hotspots predominantly form and evolve along the oxide layer interface,exhibiting a typical"hot shell-cold core"structure.A thicker oxide layer significantly delays the heating and reaction initiation of the aluminum core,with reversible crystal structure transformations observed inside the core.Larger particles facilitate heat accumulation and promote sustained reactions.As the oxide layer thickness increases,the reaction mechanism of aluminum nanoparticles transitions from melting-diffusion and micro-explosion oxidation to an oxidation-diffusion dominated process.A dense nitrogen-containing reaction layer forms on the surface,which suppresses the later-stage reaction.A nonlinear reaction kinetics model based on bond statistics reveals that particles with a thin oxide layer exhibit rapid reaction saturation and are insensitive to shock velocity.Particles with intermediate oxide thickness exhibit a reaction behavior that gradually slows down over time,while those with a thick oxide layer can exhibit accelerated reactions under high-velocity shocks due to enhanced diffusion.Small particles show significantly increased reaction rates at high velocities,whereas large particles tend to slow down due to the thickening of the surface reaction layer.The oxide layer thickness,particle size,and shock velocity exhibit complex competitive and synergistic effects that jointly regulate the initiation,rate,and evolution of aluminum nanoparticle reactions.
基金supported by National Natural Science Foundation of China (Nos.52264006,52364004,and 52464005)the Guizhou Provincial Science and Technology Foundation (No.GCC[2022]005-1)。
文摘Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.
基金supported by the National Natural Science Foundation of China(Grant Nos.12205298 and 12175230)the Natural Science Foundation of Heilongjiang Province of China(Grant No.LH2024A010)+1 种基金the Fundamental Research Funds for the Central Universities,Controversial and Disruptive Projects of the Chinese Academy of Sciences(Grant No.FGSDFX-0001)the USTC Research Funds of the Double First-Class Initiative(Grant No.YD2140002006).
文摘Quasi-hemispherical magnetized collisionless shocks have been generated at the SG-II laser facility through the interaction between a laserproduced supersonic plasma flow and a magnetized ambient plasma,exhibiting an angular asymmetric shock profile accompanied by asymmetric ion acceleration.We have conducted test particle simulations using the electromagnetic fields derived from 2D MHD simulations to investigate the asymmetry of ion acceleration.The simulations reproduce the angular asymmetry of the shock and the ion acceleration observed in experiments.The results indicate that shock drift acceleration is the primary mechanism for ion energization in the present quasiperpendicular magnetized shock.The asymmetric shock structure caused by nonuniform ambient plasma forms an asymmetric accelerated electric field,ultimately leading to angular asymmetric ion acceleration,which is consistent with space observations and our experimental results.Our study provides a plausible explanation for the discrepancies reported in previous ion acceleration experiments,and could contribute to understanding of the collisionless shock acceleration.
基金funded by the Research Fund of National Key Laboratory of Aerospace Physics in Fluids,grant number 2024-APF-KFZD-01Guangdong Basic and Applied Basic Research Foundation,grant number 2025A1515012081+1 种基金National Natural Science Foundation of China,grant number 12002193Shandong Provincial Natural Science Foundation,China,grant number ZR2019QA018.
文摘For hypersonic air-breathing vehicles,the V-shaped leading edges(VSLEs)of supersonic combustion ramjet(scramjet)inlets experience complex shock interactions and intense aerodynamic loads.This paper provides a comprehensive review of flow characteristics at the crotch of VSLEs,with particular focus on the transition of shock interaction types and the variation of wall heat flux under different freestream Mach numbers and geometric configurations.The mechanisms governing shock transition,unsteady oscillations,hysteresis,and three-dimensional effects in VSLE flows are first examined.Subsequently,thermal protection strategies aimed at mitigating extreme heating loads are reviewed,emphasizing their relevance to practical engineering applications.Special attention is given to recent studies addressing thermochemical nonequilibrium effects on VSLE shock interactions,and the limitations of current research are critically assessed.Finally,perspectives for future investigations into hypersonic VSLE shock interactions are outlined,highlighting opportunities for advancing design and thermal management strategies.
基金supported by the National Key R&D Program of China(No.2021YFC3100700)。
文摘Shock tunnels are indispensable facilities for hypersonic aerodynamic experimentation.Within these systems,the diaphragm plays a pivotal role,as its rupture process critically influences shock wave generation quality,experimental repeatability,and facility reliability.A thorough understanding of diaphragm rupture dynamics is therefore essential for optimizing shock tunnel design,improving experimental accuracy,and ensuring operational safety.To address the complex challenge of fully coupled multiphysics analysis in high-pressure-ratio shock tunnels,this study introduces a high-fidelity,three-dimensional,fully coupled Fluid-Structure Interaction(FSI)simulation framework.This framework seamlessly integrates the Dual Conservation Element and Solution Element(Dual-CESE)method,the Immersed Boundary Method(IBM),and the JohnsonCook(J-C)material constitutive and failure model.The combined approach enables synchronized simulation and analysis of the entire diaphragm rupture sequence—including pre-deformation,crack initiation and propagation,and fully developed petaling deformation—alongside the formation and evolution of the associated supersonic flow field.The simulation results show strong agreement with experimental observations,with the post-rupture geometric morphology accurately replicated and a shock wave velocity deviation of only 2.55%from experimental measurements.The study uncovers the dynamic failure mechanisms,revealing that nonlinear pressure loading initiates cracking within the diaphragm.It further elucidates how the nonlinearly coupled interactions between petaling dynamics and fracture morphology directly impact shock wave formation and evolution.This computational framework provides a novel and robust methodology for advancing shock tunnel design and conducting comprehensive reliability assessments.
基金Supported by the National Natural Science Foundation for Outstanding Young Scholars(52425402)National Natural Science Foundation of China(52341401)International(Regional)Cooperation and Exchange Program of the National Natural Science Foundation of China(W2412078)。
文摘To investigate the fracture initiation and propagation behavior of fractures in tight sandstone under the supercritical CO_(2)(SCCO_(2))shock fracturing,laboratory fracturing experiments were conducted using a true-triaxial-like SCCO_(2)shock fracturing system.Computed tomography(CT)scanning and three-dimensional fracture reconstruction were employed to elucidate the effects of shock pressure,pore pressure,and in-situ stress on fracture characteristics.In addition,nuclear magnetic resonance(NMR)transverse relaxation time spectra were used to assess the internal damage induced by SCCO_(2)shock fracturing.The results indicate that,compared with conventional hydraulic fracturing and SCCO_(2)quasi-static fracturing,SCCO_(2)shock fracturing facilitates multidirectional fracture initiation and the formation of complex fracture networks.Increasing shock pressure more readily activates bedding-plane weaknesses,with main and subsidiary fractures interweaving into a dense fracture network.Under the same impulse intensity,elevated pore pressure reduces the effective normal stress and alters stress-wave scattering paths,thereby inducing more branch fractures and enhancing fracture complexity.An increase in differential in-situ stress promotes fracture propagation along the direction of the maximum principal stress,reduces branching,and simplifies fracture morphology.With increasing SCCO_(2)shock pressure,pore volume and connectivity generally increase:small-to-medium pores primarily respond through increased number and enhanced connectivity;when the shock pressure rises to 40-45 MPa,crack coalescence generates larger pores and fissures,which play a dominant role in improving flow pathways and effective storage space,ultimately forming a multiscale pore-fracture network.
基金financial support from NSF ExpandQISE program.The synthesis of tellurene was supported by NSF under grant no.CMMI-2046936supports from Purdue Research Foundation.
文摘Tellurene,a chiral chain semiconductor with a narrow bandgap and exceptional strain sensitivity,emerges as a pivotal material for tailoring electronic and optoelectronic properties via strain engineering.This study elucidates the fundamental mechanisms of ultrafast laser shock imprinting(LSI)in two-dimensional tellurium(Te),establishing a direct relationship between strain field orientation,mold topology,and anisotropic structural evolution.This is the first demonstration of ultrafast LSI on chiral chain Te unveiling orientation-sensitive dislocation networks.By applying controlled strain fields parallel or transverse to Te’s helical chains,we uncover two distinct deformation regimes.Strain aligned parallel to the chain’s direction induces gliding and rotation governed by weak interchain interactions,preserving covalent intrachain bonds and vibrational modes.In contrast,transverse strain drives shear-mediated multimodal deformations—tensile stretching,compression,and bending—resulting in significant lattice distortions and electronic property modulation.We discovered the critical role of mold topology on deformation:sharp-edged gratings generate localized shear forces surpassing those from homogeneous strain fields via smooth CD molds,triggering dislocation tangle formation,lattice reorientation,and inhomogeneous plastic deformation.Asymmetrical strain configurations enable localized structural transformations while retaining single-crystal integrity in adjacent regions—a balance essential for functional device integration.These insights position LSI as a precision tool for nanoscale strain engineering,capable of sculpting 2D material morphologies without compromising crystallinity.By bridging ultrafast mechanics with chiral chain material science,this work advances the design of strain-tunable devices for next-generation electronics and optoelectronics,while establishing a universal framework for manipulating anisotropic 2D systems under extreme strain rates.This work discovered crystallographic orientation-dependent deformation mechanisms in 2D Te,linking parallel strain to chain gliding and transverse strain to shear-driven multimodal distortion.It demonstrates mold geometry as a critical lever for strain localization and dislocation dynamics,with sharp-edged gratings enabling unprecedented control over lattice reorientation.Crucially,the identification of strain field conditions that reconcile severe plastic deformation with single-crystal retention offers a pathway to functional nanostructure fabrication,redefining LSI’s potential in ultrafast strain engineering of chiral chain materials.
基金supported by grants from the National Natural Science Foundation of China(No.81981340417 to LiSu)Natural Science Foundation of Jiangsu Province Outstanding Youth Fund(No.BK20240134 to Yuanqing Gao).
文摘Hemorrhagic shock(HS)is a leading cause of death worldwide,particularly within the first 24 h post-injury.Current treatments are limited,especially in low-resource settings.Therapeutic hypothermia(TH)offers potential benefits by reducing metabolic demands and protecting organs,but its application in HS is challenged by cooling difficulties and side effects.This study introduces a novel nasal gel formulation of N6-cyclohexyladenosine(CHA),an adenosine A1 receptor agonist,designed to enhance brain delivery while minimizing peripheral side effects.In a mouse model of HS,administration of CHA nasal gel significantly improved survival rates,reduced metabolic rates,and protected major organs without worsening coagulopathy.Metabolomics analysis revealed a shift towards fatty acid oxidation and increased antioxidant capacity.These findings demonstrate that CHA nasal gel effectively induces TH,offering a safe and innovative treatment strategy for HS,particularly in resource-limited environments.
文摘Stator vanes especially vane suction sides of transonic turbines are subjected to high frequency excitation forces under many circumstances,and thus are exposed to the risk of high cycle fatigue.Therefore,it is necessary to reveal the flow mechanism of this kind of excitations for potential prevention measures.In this paper,the traveling shock phenomenon in the transonic turbine stator/rotor gap is observed and the concept of‘Inter-Row Traveling Shock(IRTS)'is proposed through the unsteady Reynolds-Averaged Navier-Stokes(RANS)simulation of a typical highlyloaded transonic turbine stage.The characteristics of an IRTS were described and summarized in aspects of unsteady shock wave system,aerodynamic characteristics and motion.The probable forming mechanism of an IRTS was explained through a theoretical model and it was validated through correct prediction of the flow state parameter change across the IRTS.Since IRTSs would strike onto vane suction sides,the pressure oscillation dynamic modes on vane suction side corresponding to the characteristic frequencies associated with IRTS were extracted through Dynamic Mode Decomposition(DMD),from which the way and extent of the IRTS influences on vane aerodynamic excitation were revealed and evaluated.Over 82%pressure oscillation energy on vane suction side could be brought by the IRTS sweeping along with blade rotation.
基金supported by the National Natural Science Foundation of China(Grant Nos.52205467 and U21A20138)Youth Science Foundation of Jiangsu Province(Grant No.BK20220531)Science and Technology Planning Project of Zhenjiang-International Scientific and Technological Cooperation(Grant No.GJ2023014)。
文摘Laser powder bed fusion(LPBF)is an attractive additive manufacturing technology for preparing high-performance high-entropy alloys(HEAs)engineering components.Unfortunately,the existence of inherent thermal residual stress and non-equilibrium microstructures in the additively manufactured components results in unsatisfactory mechanical properties.Herein,we propose a novel strengthening strategy,namely deep cryogenic treatment(DCT)followed by laser shock peening(LSP),to tailor the microstructures and enhance performances of an LPBF additively manufactured metastable HEA.The post-treatment effects of DCT+LSP on the LPBF-fabricated Fe_(50)Mn_(30)Co_(10)Cr_(10)HEA are evaluated in terms of microstructural modifications,residual stress,and microhardness redistribution,as well as tensile properties.Results indicate that a gradient heterogeneous structure is formed on the as-built sample surface,featuring gradient variations in grain size,martensitic phase content,and dislocation density,due to the grain refinement and martensitic phase transformation under DCT+LSP.The initial tensile residual stress on the surface is fully transformed into compressive stress,achieving a peak of-289 MPa,and the surface microhardness attains a maximum of 380.8 HV.The various strengthening mechanisms of gradient heterogeneous structures,as well as the multiple effects of heterodeformation-induced(HDI)hardening,transformation-induced plasticity(TRIP),and twinning-induced plasticity(TWIP),are responsible for achieving strength-ductility synergy.This work provides a practical pathway and valuable scientific insights for enhancing the mechanical behaviors of additively manufactured metastable HEAs via microstructural engineering.
基金founded by the Ministry of Science and Higher Education of the Russian Federation,State assignments for research,registration No.1024032600084-8-1.3.2Study of the grain growth and the formation of polycrystalline structure as a result of phase transition(Section 6)was founded by the Russian Science Foundation,Project No.24-71-00078+3 种基金https://rscf.ru/en/project/24-71-00078/(accessed on 01 December 2025).Study of the orientation dependence of the phase transition of aluminum in Section 3 was founded by the Russian Science Foundation,Project No.24-19-00684https://rscf.ru/en/project/24-19-00684/(accessed on 01 December 2025).
文摘It is well known that aluminum and copper exhibit structural phase transformations in quasi-static and dynamic measurements,including shock wave loading.However,the dependence of phase transformations in a wide range of crystallographic directions of shock loading has not been revealed.In this work,we calculated the shock Hugoniot for aluminum and copper in different crystallographic directions([100],[110],[111],[112],[102],[114],[123],[134],[221]and[401])of shock compression using molecular dynamics(MD)simulations.The results showed a high pressure(>160 GPa for Cu and>40 GPa for Al)of the FCC-to-BCC transition.In copper,different characteristics of the phase transition are observed depending on the loading direction with the[100]compression direction being the weakest.The FCC-to-BCC transition for copper is in the range of 150–220 GPa,which is consistent with the existing experimental data.Due to the high transition pressure,the BCC phase transition in copper competes with melting.In aluminum,the FCC-to-BCC transition is observed for all studied directions at pressures between 40 and 50 GPa far beyond the melting.In all considered cases we observe the coexistence of HCP and BCC phases during the FCC-to-BCC transition,which is consistent with the experimental data and atomistic calculations;this HCP phase forms in the course of accompanying plastic deformation with dislocation activity in the parent FCC phase.The plasticity incipience is also anisotropic in bothmetals,which is due to the difference in the projections of stress on the slip plane for different orientations of the FCC crystal.MD modeling results demonstrate a strong dependence of the FCC-to-BCC transition on the crystallographic direction,in which the material is loaded in the copper crystals.However,MD simulations data can only be obtained for specific points in the stereographic direction space;therefore,for more comprehensive understanding of the phase transition process,a feed-forward neural network was trained using MD modeling data.The trained machine learning model allowed us to construct continuous stereographic maps of phase transitions as a function of stress in the shock-compressed state of metal.Due to appearance and growth of multiple centers of new phase,the FCC-to-BCC transition leads to formation of a polycrystalline structure from the parent single crystal.
