Missiles provide long-range precision strike capabilities and have become a cornerstone of modern warfare.The contrail clouds formed by missile during their active flight phase present significant chal-lenges to high-...Missiles provide long-range precision strike capabilities and have become a cornerstone of modern warfare.The contrail clouds formed by missile during their active flight phase present significant chal-lenges to high-altitude environmental observation and target detection and tracking.Existing studies primarily focus on specific airspace regions,leaving critical gaps in understanding the effects of long dispersion times,wide altitude ranges,and variable atmospheric conditions on missile contrail clouds.To address these gaps,this article develops a numerical method based on the Lagrangian random walk model,which incorporates various velocity variation terms,including particle velocity caused by the difference of wind field,by the thermal motion of local gas molecules and by random collisions between contrail cloud particles to capture the influence of environmental wind fields,atmospheric conditions,and particle concentrations on the motion of contrail cloud particles.A general coordinate system aligned with the missile's flight trajectory is employed to represent particle distribution characteristics.The proposed method is in good agreement with the conducted experiments as well as with the available numerical simulations.The results demonstrate that the proposed model effectively simulates the dispersion state of contrail clouds,accurately reflecting the impact of large-scale wind field variations and altitude changes with high computational efficiency.Additionally,simulation results indicate that the increased distance between gas molecules in rarefied environments facilitates enhanced particle dispersion,while larger particles exhibit a faster dispersion rate due to their greater mass.展开更多
The dispersion of exhaust smoke particles generated during missile ignition is strongly affected by geometric confinement from launch platforms,leading to persistent smoke accumulation in the launch area,which poses s...The dispersion of exhaust smoke particles generated during missile ignition is strongly affected by geometric confinement from launch platforms,leading to persistent smoke accumulation in the launch area,which poses significant challenges for visibility control and target detection.However,existing Random Walk Model(RWM)typically rely on simplified assumptions such as free-space domains or regular boundary geometries,limiting their applicability to complex wall-constrained scenarios.To fill this gap,a Geometric Topology and Wall-Constrained Random Walk Model(GTWC-RWM)is developed to simulate particle transport in complex launch-site environments.The model incorporates wall effects—including reflection,slip,and adsorption—through ray–triangle intersection methods for collision detection.Collision response parameters are expressed as second-order polynomials of incidence angle and calibrated using experimental data to ensure physical consistency.Validation against reference data and geometric obstacle scenarios confirms the model's predictive capability,yielding a maximum relative error of less than 26.16%.Simulations reveal that wall-constrained effects significantly impede dispersion,with concentration gradients reaching up to 58.79%between obstructed and unobstructed regions.A sensitivity analysis quantifies the influence of key parameters on near-wall concentration distributions.展开更多
Realizing circularly polarized luminescence(CPL)with the same chiral direction by chiral luminogenic molecules under the identical conditions is unprecedented.Meanwhile,obtaining circularly polarized phosphorescence(C...Realizing circularly polarized luminescence(CPL)with the same chiral direction by chiral luminogenic molecules under the identical conditions is unprecedented.Meanwhile,obtaining circularly polarized phosphorescence(CPP)with a large dissymmetry factor(g_(lum))is highly significant but rather challenging.Herein,two chiral Au(I)-containing enantiomers,namely(S,S)-1 and(R,R)-1,are prepared.(S,S)-1 and(R,R)-1 show different self-assembly behaviors as the degree of aggregation in solution changes,leading to the formation of a variety of CPP signals.Notably,non-mirror-image CPP,CPP with the high g_(lum) values of+2.78×10^(−2) and−1.54×10^(−2),chirality amplification and inversion from the two chiral Au(I)luminogens are accompanied by the variation of their self-assembly morphologies.Impressively,(S,S)-1 and(R,R)-1 exhibit aggregation-induced CPP with the same chiral direction,and this is the first time that the unidirectional CPL from chiral enantiomers under the identical external environment is observed.Their respective three polymorphic crystals of(S,S)-1 and(R,R)-1,each with different packing arrangements,are fortunately obtained.The polymorphs derived from(S,S)-1 or(R,R)-1 demonstrate both M-helix and P-helix stacking arrangements.Through investigating their CPP properties,stacking modes,and intermolecular interactions of these six types of crystals cultivated by(S,S)-1 and(R,R)-1,the mechanism of their self-assembly morphologies-dependent multiple patterns CPP characteristics of(S,S)-1 and(R,R)-1 is further understood.Additionally,both(S,S)-1 and(R,R)-1 show a force-triggered CPP quenching feature,and the chiral co-assembly system with the|g_(lum)|value reaching 0.11 is gained by a combination of the synthesized enantiomers and commercial achiral liquid crystal.展开更多
文摘Missiles provide long-range precision strike capabilities and have become a cornerstone of modern warfare.The contrail clouds formed by missile during their active flight phase present significant chal-lenges to high-altitude environmental observation and target detection and tracking.Existing studies primarily focus on specific airspace regions,leaving critical gaps in understanding the effects of long dispersion times,wide altitude ranges,and variable atmospheric conditions on missile contrail clouds.To address these gaps,this article develops a numerical method based on the Lagrangian random walk model,which incorporates various velocity variation terms,including particle velocity caused by the difference of wind field,by the thermal motion of local gas molecules and by random collisions between contrail cloud particles to capture the influence of environmental wind fields,atmospheric conditions,and particle concentrations on the motion of contrail cloud particles.A general coordinate system aligned with the missile's flight trajectory is employed to represent particle distribution characteristics.The proposed method is in good agreement with the conducted experiments as well as with the available numerical simulations.The results demonstrate that the proposed model effectively simulates the dispersion state of contrail clouds,accurately reflecting the impact of large-scale wind field variations and altitude changes with high computational efficiency.Additionally,simulation results indicate that the increased distance between gas molecules in rarefied environments facilitates enhanced particle dispersion,while larger particles exhibit a faster dispersion rate due to their greater mass.
文摘The dispersion of exhaust smoke particles generated during missile ignition is strongly affected by geometric confinement from launch platforms,leading to persistent smoke accumulation in the launch area,which poses significant challenges for visibility control and target detection.However,existing Random Walk Model(RWM)typically rely on simplified assumptions such as free-space domains or regular boundary geometries,limiting their applicability to complex wall-constrained scenarios.To fill this gap,a Geometric Topology and Wall-Constrained Random Walk Model(GTWC-RWM)is developed to simulate particle transport in complex launch-site environments.The model incorporates wall effects—including reflection,slip,and adsorption—through ray–triangle intersection methods for collision detection.Collision response parameters are expressed as second-order polynomials of incidence angle and calibrated using experimental data to ensure physical consistency.Validation against reference data and geometric obstacle scenarios confirms the model's predictive capability,yielding a maximum relative error of less than 26.16%.Simulations reveal that wall-constrained effects significantly impede dispersion,with concentration gradients reaching up to 58.79%between obstructed and unobstructed regions.A sensitivity analysis quantifies the influence of key parameters on near-wall concentration distributions.
基金funded by the National Natural Science Foundation of China(22175069 and 22361020)the Academic and Technical Leader Plan of Jiangxi Provincial Main Disciplines(20212BCJ23004).
文摘Realizing circularly polarized luminescence(CPL)with the same chiral direction by chiral luminogenic molecules under the identical conditions is unprecedented.Meanwhile,obtaining circularly polarized phosphorescence(CPP)with a large dissymmetry factor(g_(lum))is highly significant but rather challenging.Herein,two chiral Au(I)-containing enantiomers,namely(S,S)-1 and(R,R)-1,are prepared.(S,S)-1 and(R,R)-1 show different self-assembly behaviors as the degree of aggregation in solution changes,leading to the formation of a variety of CPP signals.Notably,non-mirror-image CPP,CPP with the high g_(lum) values of+2.78×10^(−2) and−1.54×10^(−2),chirality amplification and inversion from the two chiral Au(I)luminogens are accompanied by the variation of their self-assembly morphologies.Impressively,(S,S)-1 and(R,R)-1 exhibit aggregation-induced CPP with the same chiral direction,and this is the first time that the unidirectional CPL from chiral enantiomers under the identical external environment is observed.Their respective three polymorphic crystals of(S,S)-1 and(R,R)-1,each with different packing arrangements,are fortunately obtained.The polymorphs derived from(S,S)-1 or(R,R)-1 demonstrate both M-helix and P-helix stacking arrangements.Through investigating their CPP properties,stacking modes,and intermolecular interactions of these six types of crystals cultivated by(S,S)-1 and(R,R)-1,the mechanism of their self-assembly morphologies-dependent multiple patterns CPP characteristics of(S,S)-1 and(R,R)-1 is further understood.Additionally,both(S,S)-1 and(R,R)-1 show a force-triggered CPP quenching feature,and the chiral co-assembly system with the|g_(lum)|value reaching 0.11 is gained by a combination of the synthesized enantiomers and commercial achiral liquid crystal.
