The mating systems and floral traits often among relatives of hermaphroditic plants can exhibit considerable diversity.This diversity can be influenced by the evolution of selfing and associated floral traits as a for...The mating systems and floral traits often among relatives of hermaphroditic plants can exhibit considerable diversity.This diversity can be influenced by the evolution of selfing and associated floral traits as a form of reproductive assurance(RA)when pollen limitation(PL)results from insufficient pollinator availability.To explore whether the degree of PL primarily drives differences in mating systems and floral traits,we conducted a comprehensive study involving two closely related species,Halenia elliptica and Halenia grandiflora,in three sympatric sites.We investigated floral characteristics,pollinator visitation,PL,autonomous selfing ability,RA and mating system in studied populations.Our findings show that H.elliptica produces smaller flowers and less nectar production than H.grandiflora,making it less attractive to pollinators.Compared with H.grandiflora,H.elliptica experienced more severe outcross pollen limitation(OPL),but compensates with a higher capacity for autonomous selfing,ensuring seed production under natural conditions.Moreover,significant differences in mating systems were detected between them,with H.elliptica exhibiting a higher selfing rate than H.grandiflora across all studied sympatric populations.These differences are also reflected in variations in herkogamy and dichogamy.Our study suggested that the degree of OPL impacts the divergence in mating systems and floral traits between sympatric closely related species,offering valuable insights into the evolution of plant mating systems and floral traits.展开更多
With the collapse of cavitation bubbles near the wall,micro-jets and shock waves will be formed,to generate a high-pressure load and to cause the cavitation damage on the surface of the hydraulic machinery.Due to the ...With the collapse of cavitation bubbles near the wall,micro-jets and shock waves will be formed,to generate a high-pressure load and to cause the cavitation damage on the surface of the hydraulic machinery.Due to the rapid development of the cavitation bubble collapse process(in the time scale of hundred nanoseconds),the time resolution of the conventional high-speed cameras should reach more than one million frames per second,which will limit the spatial resolution,and obscure the details of the cavitation bubble shape near the cavitation bubble collapse moment.In this paper,with the help of the laser cavitation bubble photogrammetry system with nanosecond-micron space-time resolution,the experiment is carried out for the cavitation bubble collapse morphology evolution near the wall.The morphological characteristics of the cavitation bubble collapse at specific times are analyzed.With the help of the OpenFOAM code,the collapse process of the cavitation bubble near the solid wall is calculated.It is shown that the cavitation bubble near the wall collapses in an axial symmetric heart shape and the micro-jet directed to the wall will pull the cavitation bubble towards the wall.The counter-jet generated in the rebound stage will drive the cavitation bubble to move away from the wall.The numerical simulation of the cavitation bubble shape in the collapse period is well consistent with the experimental results,but the ability to capture the shock wavefront needs to be improved.Under the conditions studied in this paper,the cavitation bubble collapse micro-jet velocity can reach up to a hundred meters per second both in the experiment and the numerical simulation.展开更多
To investigate the mechanism of cavitation erosion caused by laser-induced single bubble near the surface coating alloy coating material, we utilized a nanosecond resolution photography system based on a Q-switched Nd...To investigate the mechanism of cavitation erosion caused by laser-induced single bubble near the surface coating alloy coating material, we utilized a nanosecond resolution photography system based on a Q-switched Nd: YAG laser and conventional industrial camera to carefully observe the transient process of bubble collapse under different conditions. We analyzed the generation of collapse microjets and the emission of collapse shock waves and explored the cavitation erosion characteristics caused by laser-induced single bubble collapse. We discovered that even on surfaces of highly hard and corrosion-resistant alloy coatings, severe cavitation erosion occurred, and there was a phenomenon of mismatch between the cavitation erosion location and the bubble projection position. The intensity of cavitation erosion depended on the energy self-focusing effect of the collapse shockwaves. In the experiments, we also observed the self-focusing phenomenon of collapse shockwaves under different conditions. The self-focusing effect of collapse shockwaves weakened as the distance between the bubble and the material surface increased, which may be the cause of cavitation erosion induced by a laser-induced single bubble.展开更多
The presence of a rigid wall causes a microjet of the cavitation bubble to collapse to move toward the wall,while a free surface does the opposite.When a rigid wall surface is combined with a free surface,it may affec...The presence of a rigid wall causes a microjet of the cavitation bubble to collapse to move toward the wall,while a free surface does the opposite.When a rigid wall surface is combined with a free surface,it may affect the direction of the microjet.The motive of this study is to find out the influence of the dynamic behavior of a laser-induced bubble near the rigid wall with a gas-containing hole.Evolutions of the bubble at different distances from the gas-containing hole in the horizontal and vertical directions were recorded by a high-speed camera(2.3×10^(5) fps).When the bubble collapse near the boundary,the bubble will produce two situations:away from or toward the boundary.It focuses on the direction of the bubble,the oscillation period of a bubble,and reflection angle,and quantitative analysis of the results.It was found that the boundary not only changes the morphologic of the bubble and the overall direction of movement but also affects the oscillation period.In addition,it can control the deflection of the bubble.展开更多
基金supported by the National Natural Science Foundation of China(32271693)the Cultivating Plan Program for the Leader in Science and Technology of Yunnan Province(202405AC350111).
文摘The mating systems and floral traits often among relatives of hermaphroditic plants can exhibit considerable diversity.This diversity can be influenced by the evolution of selfing and associated floral traits as a form of reproductive assurance(RA)when pollen limitation(PL)results from insufficient pollinator availability.To explore whether the degree of PL primarily drives differences in mating systems and floral traits,we conducted a comprehensive study involving two closely related species,Halenia elliptica and Halenia grandiflora,in three sympatric sites.We investigated floral characteristics,pollinator visitation,PL,autonomous selfing ability,RA and mating system in studied populations.Our findings show that H.elliptica produces smaller flowers and less nectar production than H.grandiflora,making it less attractive to pollinators.Compared with H.grandiflora,H.elliptica experienced more severe outcross pollen limitation(OPL),but compensates with a higher capacity for autonomous selfing,ensuring seed production under natural conditions.Moreover,significant differences in mating systems were detected between them,with H.elliptica exhibiting a higher selfing rate than H.grandiflora across all studied sympatric populations.These differences are also reflected in variations in herkogamy and dichogamy.Our study suggested that the degree of OPL impacts the divergence in mating systems and floral traits between sympatric closely related species,offering valuable insights into the evolution of plant mating systems and floral traits.
基金supported by the National Natural Science Foundation of China(Grant No.5217090233).
文摘With the collapse of cavitation bubbles near the wall,micro-jets and shock waves will be formed,to generate a high-pressure load and to cause the cavitation damage on the surface of the hydraulic machinery.Due to the rapid development of the cavitation bubble collapse process(in the time scale of hundred nanoseconds),the time resolution of the conventional high-speed cameras should reach more than one million frames per second,which will limit the spatial resolution,and obscure the details of the cavitation bubble shape near the cavitation bubble collapse moment.In this paper,with the help of the laser cavitation bubble photogrammetry system with nanosecond-micron space-time resolution,the experiment is carried out for the cavitation bubble collapse morphology evolution near the wall.The morphological characteristics of the cavitation bubble collapse at specific times are analyzed.With the help of the OpenFOAM code,the collapse process of the cavitation bubble near the solid wall is calculated.It is shown that the cavitation bubble near the wall collapses in an axial symmetric heart shape and the micro-jet directed to the wall will pull the cavitation bubble towards the wall.The counter-jet generated in the rebound stage will drive the cavitation bubble to move away from the wall.The numerical simulation of the cavitation bubble shape in the collapse period is well consistent with the experimental results,but the ability to capture the shock wavefront needs to be improved.Under the conditions studied in this paper,the cavitation bubble collapse micro-jet velocity can reach up to a hundred meters per second both in the experiment and the numerical simulation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52179092,52222904).
文摘To investigate the mechanism of cavitation erosion caused by laser-induced single bubble near the surface coating alloy coating material, we utilized a nanosecond resolution photography system based on a Q-switched Nd: YAG laser and conventional industrial camera to carefully observe the transient process of bubble collapse under different conditions. We analyzed the generation of collapse microjets and the emission of collapse shock waves and explored the cavitation erosion characteristics caused by laser-induced single bubble collapse. We discovered that even on surfaces of highly hard and corrosion-resistant alloy coatings, severe cavitation erosion occurred, and there was a phenomenon of mismatch between the cavitation erosion location and the bubble projection position. The intensity of cavitation erosion depended on the energy self-focusing effect of the collapse shockwaves. In the experiments, we also observed the self-focusing phenomenon of collapse shockwaves under different conditions. The self-focusing effect of collapse shockwaves weakened as the distance between the bubble and the material surface increased, which may be the cause of cavitation erosion induced by a laser-induced single bubble.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91852101,91952301,52179092 and 52179081).
文摘The presence of a rigid wall causes a microjet of the cavitation bubble to collapse to move toward the wall,while a free surface does the opposite.When a rigid wall surface is combined with a free surface,it may affect the direction of the microjet.The motive of this study is to find out the influence of the dynamic behavior of a laser-induced bubble near the rigid wall with a gas-containing hole.Evolutions of the bubble at different distances from the gas-containing hole in the horizontal and vertical directions were recorded by a high-speed camera(2.3×10^(5) fps).When the bubble collapse near the boundary,the bubble will produce two situations:away from or toward the boundary.It focuses on the direction of the bubble,the oscillation period of a bubble,and reflection angle,and quantitative analysis of the results.It was found that the boundary not only changes the morphologic of the bubble and the overall direction of movement but also affects the oscillation period.In addition,it can control the deflection of the bubble.
