In recent years,the demand for synchronous acquisition of three-dimensional(3D)shape and col-or texture has surged in fields such as cultural heritage preservation and healthcare.Addressing this need,this paper propos...In recent years,the demand for synchronous acquisition of three-dimensional(3D)shape and col-or texture has surged in fields such as cultural heritage preservation and healthcare.Addressing this need,this paper proposes a novel method for simultaneous 3D shape and color texture capture.First,a linear model correlating camera exposure time with grayscale values is established.Through exposure time calibration,the projected red,green and blue(RGB)light and white-light grayscale values captured by a monochrome cam-era are aligned.Then,three sets of color fringes are projected onto the object to identify optimal pixels for 3D reconstruction.And,three pure-color patterns are projected to synthesize the color texture.Experimental res-ults show that this method effectively achieves synchronous 3D shape and color texture acquisition,offering high speed and precision,and avoids color crosstalk interference common in 3D reconstruction of colored ob-jects using a monochrome camera.展开更多
In this study,selective laser melting(SLM)technology was used to prepare multi-ratio tungsten-based composite material liners,and the feasibility of its application in the field of shaped charge penetration was system...In this study,selective laser melting(SLM)technology was used to prepare multi-ratio tungsten-based composite material liners,and the feasibility of its application in the field of shaped charge penetration was systematically evaluated.Four types of tungsten composite material liners with gradient tungsten content(80W,84W,88W,and 93W)were successfully fabricated using SLM.Detailed microstructural characterization(via optical microscopy),quasi-static compression tests,and dynamic mechanical evaluations using a Split Hopkinson Pressure Bar(SHPB)were conducted,with particular focus on the 84W and 88W compositions.Static penetration tests were performed to quantitatively assess the jet performance as a function of tungsten content and to elucidate the underlying penetration mechanisms.Experimental results revealed that SLM-fabricated samples exhibited dense microstructures free from cracks or major defects.Under quasi-static loading,the compressive strengths of 88W and 84W com-posite materials reached 1176 MPa and 1056 MPa,respectively,reflecting an 11.36%increase in strength with higher tungsten content.During low strain rate deformation,plastic flow was primarily governed by the ductile Ni-Fe binder phase.Jet penetration testing demonstrated a strong positive correlation between tungsten content and armor-piercing performance:the 93W jet achieved a 232.4%increase in penetration depth and a 25.5%reduction in crater diameter compared to the 80W jet.The findings confirm that SLM-fabricated tungsten-based liners possess substantial armor-penetrating capability.The established quantitative relationship between processing reliability and material performance provides theoretical and technical support for the engineering application of additive manufacturing in the field of shaped charge jet formation and penetration.展开更多
The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect,while at low velocities,the strength effect becomes predominant.In the latter regime,mate...The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect,while at low velocities,the strength effect becomes predominant.In the latter regime,material strength dictates the resistance to plastic deformation and flow,a contrast to the shockwave-dominated interactions where compressibility is key.This paper presents a self-consistent compressible penetration theory that considers both the axial penetration and radial crater growth of shaped charge jets into targets.An integrated approach where the axial and radial dynamics are coupled has been proposed,influencing each other through shared physical principles rather than being treated as separate,empirically linked phenomena.The presented theory is rooted in the compressible Bernoulli equation and the linear Rankine-Hugoniot relation.These foundational equations are employed to accurately model the high-pressure shock state and subsequent material flow at the jet-target interface,providing a robust physical basis for the penetration model.Notably,it considers the target material's compressibility,which elevates the pressure at the jet-target interface beyond that observed with incompressible materials.This pressure increase is directly proportional to the target's degree of compressibility.As such,this model of compressible penetration reorients the analytical approach:rather than merely estimating penetration resistance,it determines this value from the target material's specific compressibility and yield strength.This shift from empirical correlations to a physics-based derivation of penetration resistance enhances the model's predictive power,particularly for novel target materials or engagement conditions outside established experimental datasets.This investigation establishes a quantitative link between the material's yield strength and its penetration resistance.The accuracy of this penetration resistance value is paramount,as it significantly influences the predicted crater diameter;indeed,the crater diameter's sensitivity to this resistance underscores the necessity for its precise determination.Ultimately,by integrating the yield strength of the target material,this framework enables the prediction of both the penetration depth and the resultant crater diameter from a shaped charge jet.The theory's validation involved two experimental sets:the first focused on shaped charge jet penetration into 45#steel at varied stand-offs,while the second utilized targets of high-to ultrahigh-strength steel-fiber reactive powder concrete(RPC)with differing strength characteristics.These experimental campaigns were specifically chosen to test the theory against both ductile metallic alloys,where plastic flow is significant,and advanced quasi-brittle cementitious composites,presenting a broad spectrum of material responses and penetration challenges.Resulting hole profiles derived from theoretical calculations demonstrated a strong correspondence with empirical measurements for both material types.展开更多
Shaped charge has been widely used for penetrating concrete.However,due to the obvious difference between the propagation of shock waves and explosion products in water and air,the theory governing the formation of sh...Shaped charge has been widely used for penetrating concrete.However,due to the obvious difference between the propagation of shock waves and explosion products in water and air,the theory governing the formation of shaped charge jets in water as well as the underwater penetration effect of concrete need to be studied.In this paper,we introduced a modified forming theory of an underwater hemispherical shaped charge,and investigated the behavior of jet formation and concrete penetration in both air and water experimentally and numerically.The results show that the modified jet forming theory predicts the jet velocity of the hemispherical liner with an error of less than 10%.The underwater jets exhibit at least 3%faster and 11%longer than those in air.Concrete shows different failure modes after penetration in air and water.The depth of penetration deepens at least 18.75%after underwater penetration,accompanied by deeper crater with 65%smaller radius.Moreover,cracks throughout the entire target are formed,whereas cracks exist only near the penetration hole in air.This comprehensive study provides guidance for optimizing the structure of shaped charge and improves the understanding of the permeability effect of concrete in water.展开更多
The cavity characteristics in liquid-filled containers caused by high-velocity impacts represent an important area of research in hydrodynamic ram phenomena.The dynamic expansion of the cavity induces liquid pressure ...The cavity characteristics in liquid-filled containers caused by high-velocity impacts represent an important area of research in hydrodynamic ram phenomena.The dynamic expansion of the cavity induces liquid pressure variations,potentially causing catastrophic damage to the container.Current studies mainly focus on non-deforming projectiles,such as fragments,with limited exploration of shaped charge jets.In this paper,a uniquely experimental system was designed to record cavity profiles in behind-armor liquid-filled containers subjected to shaped charge jet impacts.The impact process was then numerically reproduced using the explicit simulation program ANSYS LS-DYNA with the Structured Arbitrary Lagrangian-Eulerian(S-ALE)solver.The formation mechanism,along with the dimensional and shape evolution of the cavity was investigated.Additionally,the influence of the impact kinetic energy of the jet on the cavity characteristics was analyzed.The findings reveal that the cavity profile exhibits a conical shape,primarily driven by direct jet impact and inertial effects.The expansion rates of both cavity length and maximum radius increase with jet impact kinetic energy.When the impact kinetic energy is reduced to 28.2 kJ or below,the length-to-diameter ratio of the cavity ultimately stabilizes at approximately 7.展开更多
Fine tailoring the shape of nanosheets is still a big challenge as the difficult synthesis for highly controlled ultrathin nanosheets.Here we report a facile strategy for tailoring the shape of ultra-thin NdF_(3) nano...Fine tailoring the shape of nanosheets is still a big challenge as the difficult synthesis for highly controlled ultrathin nanosheets.Here we report a facile strategy for tailoring the shape of ultra-thin NdF_(3) nanosheets via a hot injection method.In this method,NdF_(3) nanosheets with only about 2 nm in thickness synthesized first via a hot injection method.The shape of the NdF_(3) nanosheets was able to be tailored from flower-like to the round or the triangular shapes simply by decreasing the reaction temperature from 300℃to 280℃or 260℃.The driven force of the NdF_(3) nanosheets’shape tailoring by the temperature could be that a lower crystal growth rate will guarantee the more stable facets exposed at lower temperature,while under the condition of slow precursor injection,a higher temperature will lead to a further decrease in the crystal growth rate.This shape control method of NdF_(3) nanosheets is highly robust,which could be promoted to other materials.展开更多
Surface topography analysis plays an important role in tribology.The electron microscope and the optical microscope are typically used to characterize surfaces topography in tribology.Optical microscope is suitable to...Surface topography analysis plays an important role in tribology.The electron microscope and the optical microscope are typically used to characterize surfaces topography in tribology.Optical microscope is suitable to acquire in situ surface morphology and geometric feature of worn surface.However,two-dimensional(2D)optical image is less intuitive than the three-dimensional(3D)image.In order to visualize the worn surface with 3D image,the shape from shading(SFS)technique has been used to reconstruct the 3D topographic diagram from the single optical image.Tribological experiments on Ti6Al4V worn surfaces have been performed to obtain the 2D optical images,and then 3D reconstruction has been achieved via SFS method.To validate the accuracy of SFS technique,the surface profile transversal,roughness parameters and the areal field parameters of the target area on worn surface from laser scan confocal microscope(LSCM)have been used to compare with the data from SFS.It is found that the largest height deviation of selected feature points in surface profile transversals between SFS technique and LSCM method is no more than 15%.The maximum peak height(R_(p))between SFS and LSCM is 0.40μm with relative deviation around 13.70%.The largest absolute deviation of maximum peak height(Sp)is 0.60μm with the maximum relative deviation 17.91%.The above result show that the 3D topography of the worn Ti6Al4V surface reconstructed from 2D optical image by SFS technique is comparable to that obtained from LSCM method,which proves the reliability of SFS technique in image processing of worn surfaces.展开更多
In this study,the potential application of shaped charge jets as transient antennas for electromagnetic signal transmission was explored and an electromagnetic pulse radiation system with a shaped charge jet as a tran...In this study,the potential application of shaped charge jets as transient antennas for electromagnetic signal transmission was explored and an electromagnetic pulse radiation system with a shaped charge jet as a transient antenna was proposed.During the research,crucial characteristics of the transient antenna formed by a shaped charge with a 30 mm diameter,such as resonant frequency,radiation pattern,and radiation efficiency,were evaluated.The typical shaped charge jet morphology was obtained based on the simulations,in which it could insight the dynamic behavior of the shaped charge jet selected.An equivalent model experiment was employed to test the radiation efficiency,and it showed that a shorting pin loading method could increase the relative bandwidth of the jet antenna to 32.8%,and the experimental results correlate with the theoretical predictions for half-wave dipole antennas reasonably well.Additionally,variations in the diameter of the shaped charge jet were found to affect the input impedance and impedance bandwidth,while the length of the jet influenced the resonant frequency of the antenna.This suggests that altering these parameters can achieve reconfigurability of the jet antenna.展开更多
Background Cotton is a significant crop for fiber production;however,seed shape-related traits have been less investigated in comparison to fiber quality.Comprehending the genetic foundation of traits associated with ...Background Cotton is a significant crop for fiber production;however,seed shape-related traits have been less investigated in comparison to fiber quality.Comprehending the genetic foundation of traits associated with seed shape is crucial for improving the seed and fiber quality in cotton.Results A total of 238 cotton accessions were evaluated in four different environments over a period of two years.Traits including thousand grain weight(TGW),aspect ratio(AR),seed length,seed width,diameter,and roundness demonstrated high heritability and significant genetic variation,as indicated by phenotypic analysis.The association analysis involved 145 simple sequence repeats(SSR)markers and identified 50 loci significantly associated with six traits related to seed shape.The markers MON_DPL0504aa and BNL2535ba were identified as influencing multiple traits,including aspect ratio and thousand grain weight.Notably,markers such as HAU2588a and MUSS422aa had considerable influence on seed diameter and roundness.The identified markers represented an average phenotypic variance between 3.92%for seed length and 16.54%for TGW.Conclusions The research finds key loci for seed shape-related traits in cotton,providing significant potential for marker-assisted breeding.These findings establish a framework for breeding initiatives focused on enhancing seed quality,hence advancing the cotton production.展开更多
The impact of high-velocity penetrators into liquid-filled containers can generate hydrodynamic ram effects,potentially causing catastrophic structural damage to the container.Previous studies have primarily focused o...The impact of high-velocity penetrators into liquid-filled containers can generate hydrodynamic ram effects,potentially causing catastrophic structural damage to the container.Previous studies have primarily focused on undeformed penetrators,such as fragments or bullets,with limited attention directed toward shaped charge jets.This study investigates the penetration characteristics of shaped charge jets impacting behind-armor liquid-filled containers,with particular emphasis on jet-liquid interactions.A theoretical penetration model incorporating material compressibility and jet stretching was developed based on the virtual origin theory.A high-speed imaging experimental system was designed to capture the jet motion within the container.The impact process was numerically reproduced using ANSYS/LSDYNA,and the effects of standoff and overmatch on jet penetration were analyzed.The results reveal that jet stretching induced by increased standoff enhances the penetration velocity of the jet.A proportional relationship between the stretching factor(λ)and the overmatch parameter(I)was identified,withλranging from approximately 1.22 to 1.38 times I across the studied standoff range(80-220 mm).The findings offer a basis for future studies on the pressure distribution in the liquid and the structural response of containers.展开更多
An analysis of the interaction mechanisms between a Shaped Charge Jet(SCJ) and a single Moving Plate(MP) is proposed in this article using both experimental and numerical approaches. First, an experimental set-up is p...An analysis of the interaction mechanisms between a Shaped Charge Jet(SCJ) and a single Moving Plate(MP) is proposed in this article using both experimental and numerical approaches. First, an experimental set-up is presented. Four collision tests have been performed: two tests in Backward Moving Plate(BMP) configuration, where the plate moves in opposition to jet, and two tests in Forward Moving Plate(FMP) configuration, where the plate moves alongside the jet. Based on the virtual origin approximation,a methodology(the Virtual Origin Method, VOM) is developed to extract quantities from the X-ray images, which serve as comparative data. γSPH simulations are carried out to complete the analysis, as they well capture the disturbance dynamics observed in the experiments. Based on these complementary experimental and numerical results, a new physical description is proposed through a detailed analysis of the interaction. It is shown that the SCJ/MP interaction is driven at first order by the contact geometry. Thus, BMP and FMP configurations do not generate the same disturbances because their local flow geometries are different. In the collision point frame of reference, the BMP flows in the same direction as the jet, causing its overall deflection. On the contrary, the FMP flow opposes that of the jet leading to an alternative creation of fragments and ligaments. An in-depth study, using the VOM shows that deflection angles, fragment-ligament creation frequencies, and deflection velocities evolve as the interaction progresses through slower jet elements.展开更多
The shape of underground chambers in deep mining varies due to their geological environment and intended use,which results in different failure modes under the influence of mining activities.However,the effect of cham...The shape of underground chambers in deep mining varies due to their geological environment and intended use,which results in different failure modes under the influence of mining activities.However,the effect of chamber shape on the mechanism of structural integrity under dynamic load is still unclear.In this paper,granite samples with circular(C),rectangular(R),long ellipse(EL),and short ellipse(ES)holes were prepared.The dynamic mechanical response and cracking mechanism of granite were systematically analyzed using the split Hopkinson pressure bar(SHPB)test system and the hybrid finite and discrete element method(HFDEM).The results indicate that the dynamic strengths of granite with EL and ES represent the maximum and minimum values within the range of close strain rates,respectively.When EL granite is subjected to dynamic load,the axial stress concentration(in the load direction)is weak,and the transverse stress shows relative dispersion,which is the primary reason for its highest dynamic strength.The failure of granite with various holes primarily involves a tensile-shear mixed fracture,with relatively few pure typeⅡcracks.The chamber’s transverse span is the primary factor influencing the distribution range of the fracture area.展开更多
A high-precision shape detecting system of cold rolling strip is developed to meet industrial application, which mainly consists of the shape detecting roller, the collecting ring, the digital signal processing （DSP...A high-precision shape detecting system of cold rolling strip is developed to meet industrial application, which mainly consists of the shape detecting roller, the collecting ring, the digital signal processing （DSP） shape signal processing board and the shape control model. Based on the shape detecting principle, the shape detecting roller is designed with a new integral structure for improving the precision of shape detecting and avoiding scratching strip surface. Based on the DSP technology, the DSP shape signal processing circuit board is designed and embedded in the shape detecting system for the reliability and stability of shape signal processing. The shape detecting system was successfully used in Angang 1 250 mm HC 6-high reversible cold rolling mill. The precision of shape detecting is 0.2 I and the shape deviation is controlled within 6 1 after the close loop shape control is input.展开更多
文摘In recent years,the demand for synchronous acquisition of three-dimensional(3D)shape and col-or texture has surged in fields such as cultural heritage preservation and healthcare.Addressing this need,this paper proposes a novel method for simultaneous 3D shape and color texture capture.First,a linear model correlating camera exposure time with grayscale values is established.Through exposure time calibration,the projected red,green and blue(RGB)light and white-light grayscale values captured by a monochrome cam-era are aligned.Then,three sets of color fringes are projected onto the object to identify optimal pixels for 3D reconstruction.And,three pure-color patterns are projected to synthesize the color texture.Experimental res-ults show that this method effectively achieves synchronous 3D shape and color texture acquisition,offering high speed and precision,and avoids color crosstalk interference common in 3D reconstruction of colored ob-jects using a monochrome camera.
基金funded by the China Postdoctoral Science Foundation (Grant No. 2022M721614)the opening project of State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology (Grant No. KFJJ2307M)
文摘In this study,selective laser melting(SLM)technology was used to prepare multi-ratio tungsten-based composite material liners,and the feasibility of its application in the field of shaped charge penetration was systematically evaluated.Four types of tungsten composite material liners with gradient tungsten content(80W,84W,88W,and 93W)were successfully fabricated using SLM.Detailed microstructural characterization(via optical microscopy),quasi-static compression tests,and dynamic mechanical evaluations using a Split Hopkinson Pressure Bar(SHPB)were conducted,with particular focus on the 84W and 88W compositions.Static penetration tests were performed to quantitatively assess the jet performance as a function of tungsten content and to elucidate the underlying penetration mechanisms.Experimental results revealed that SLM-fabricated samples exhibited dense microstructures free from cracks or major defects.Under quasi-static loading,the compressive strengths of 88W and 84W com-posite materials reached 1176 MPa and 1056 MPa,respectively,reflecting an 11.36%increase in strength with higher tungsten content.During low strain rate deformation,plastic flow was primarily governed by the ductile Ni-Fe binder phase.Jet penetration testing demonstrated a strong positive correlation between tungsten content and armor-piercing performance:the 93W jet achieved a 232.4%increase in penetration depth and a 25.5%reduction in crater diameter compared to the 80W jet.The findings confirm that SLM-fabricated tungsten-based liners possess substantial armor-penetrating capability.The established quantitative relationship between processing reliability and material performance provides theoretical and technical support for the engineering application of additive manufacturing in the field of shaped charge jet formation and penetration.
基金the Fundamental Research Funds for the Central Universities of Nanjing University of Science and Technology(CN)under Grant No.30924010803。
文摘The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect,while at low velocities,the strength effect becomes predominant.In the latter regime,material strength dictates the resistance to plastic deformation and flow,a contrast to the shockwave-dominated interactions where compressibility is key.This paper presents a self-consistent compressible penetration theory that considers both the axial penetration and radial crater growth of shaped charge jets into targets.An integrated approach where the axial and radial dynamics are coupled has been proposed,influencing each other through shared physical principles rather than being treated as separate,empirically linked phenomena.The presented theory is rooted in the compressible Bernoulli equation and the linear Rankine-Hugoniot relation.These foundational equations are employed to accurately model the high-pressure shock state and subsequent material flow at the jet-target interface,providing a robust physical basis for the penetration model.Notably,it considers the target material's compressibility,which elevates the pressure at the jet-target interface beyond that observed with incompressible materials.This pressure increase is directly proportional to the target's degree of compressibility.As such,this model of compressible penetration reorients the analytical approach:rather than merely estimating penetration resistance,it determines this value from the target material's specific compressibility and yield strength.This shift from empirical correlations to a physics-based derivation of penetration resistance enhances the model's predictive power,particularly for novel target materials or engagement conditions outside established experimental datasets.This investigation establishes a quantitative link between the material's yield strength and its penetration resistance.The accuracy of this penetration resistance value is paramount,as it significantly influences the predicted crater diameter;indeed,the crater diameter's sensitivity to this resistance underscores the necessity for its precise determination.Ultimately,by integrating the yield strength of the target material,this framework enables the prediction of both the penetration depth and the resultant crater diameter from a shaped charge jet.The theory's validation involved two experimental sets:the first focused on shaped charge jet penetration into 45#steel at varied stand-offs,while the second utilized targets of high-to ultrahigh-strength steel-fiber reactive powder concrete(RPC)with differing strength characteristics.These experimental campaigns were specifically chosen to test the theory against both ductile metallic alloys,where plastic flow is significant,and advanced quasi-brittle cementitious composites,presenting a broad spectrum of material responses and penetration challenges.Resulting hole profiles derived from theoretical calculations demonstrated a strong correspondence with empirical measurements for both material types.
基金supported by the National Science Foundation of China(Grant Nos.12372361,12102427,12372335 and 12102202)the Fundamental Research Funds for the Central Universities(Grant No.30923010908)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX23_0520).
文摘Shaped charge has been widely used for penetrating concrete.However,due to the obvious difference between the propagation of shock waves and explosion products in water and air,the theory governing the formation of shaped charge jets in water as well as the underwater penetration effect of concrete need to be studied.In this paper,we introduced a modified forming theory of an underwater hemispherical shaped charge,and investigated the behavior of jet formation and concrete penetration in both air and water experimentally and numerically.The results show that the modified jet forming theory predicts the jet velocity of the hemispherical liner with an error of less than 10%.The underwater jets exhibit at least 3%faster and 11%longer than those in air.Concrete shows different failure modes after penetration in air and water.The depth of penetration deepens at least 18.75%after underwater penetration,accompanied by deeper crater with 65%smaller radius.Moreover,cracks throughout the entire target are formed,whereas cracks exist only near the penetration hole in air.This comprehensive study provides guidance for optimizing the structure of shaped charge and improves the understanding of the permeability effect of concrete in water.
基金financial support from the National Natural Science Foundation of China(Grant No.11572159).
文摘The cavity characteristics in liquid-filled containers caused by high-velocity impacts represent an important area of research in hydrodynamic ram phenomena.The dynamic expansion of the cavity induces liquid pressure variations,potentially causing catastrophic damage to the container.Current studies mainly focus on non-deforming projectiles,such as fragments,with limited exploration of shaped charge jets.In this paper,a uniquely experimental system was designed to record cavity profiles in behind-armor liquid-filled containers subjected to shaped charge jet impacts.The impact process was then numerically reproduced using the explicit simulation program ANSYS LS-DYNA with the Structured Arbitrary Lagrangian-Eulerian(S-ALE)solver.The formation mechanism,along with the dimensional and shape evolution of the cavity was investigated.Additionally,the influence of the impact kinetic energy of the jet on the cavity characteristics was analyzed.The findings reveal that the cavity profile exhibits a conical shape,primarily driven by direct jet impact and inertial effects.The expansion rates of both cavity length and maximum radius increase with jet impact kinetic energy.When the impact kinetic energy is reduced to 28.2 kJ or below,the length-to-diameter ratio of the cavity ultimately stabilizes at approximately 7.
文摘Fine tailoring the shape of nanosheets is still a big challenge as the difficult synthesis for highly controlled ultrathin nanosheets.Here we report a facile strategy for tailoring the shape of ultra-thin NdF_(3) nanosheets via a hot injection method.In this method,NdF_(3) nanosheets with only about 2 nm in thickness synthesized first via a hot injection method.The shape of the NdF_(3) nanosheets was able to be tailored from flower-like to the round or the triangular shapes simply by decreasing the reaction temperature from 300℃to 280℃or 260℃.The driven force of the NdF_(3) nanosheets’shape tailoring by the temperature could be that a lower crystal growth rate will guarantee the more stable facets exposed at lower temperature,while under the condition of slow precursor injection,a higher temperature will lead to a further decrease in the crystal growth rate.This shape control method of NdF_(3) nanosheets is highly robust,which could be promoted to other materials.
文摘Surface topography analysis plays an important role in tribology.The electron microscope and the optical microscope are typically used to characterize surfaces topography in tribology.Optical microscope is suitable to acquire in situ surface morphology and geometric feature of worn surface.However,two-dimensional(2D)optical image is less intuitive than the three-dimensional(3D)image.In order to visualize the worn surface with 3D image,the shape from shading(SFS)technique has been used to reconstruct the 3D topographic diagram from the single optical image.Tribological experiments on Ti6Al4V worn surfaces have been performed to obtain the 2D optical images,and then 3D reconstruction has been achieved via SFS method.To validate the accuracy of SFS technique,the surface profile transversal,roughness parameters and the areal field parameters of the target area on worn surface from laser scan confocal microscope(LSCM)have been used to compare with the data from SFS.It is found that the largest height deviation of selected feature points in surface profile transversals between SFS technique and LSCM method is no more than 15%.The maximum peak height(R_(p))between SFS and LSCM is 0.40μm with relative deviation around 13.70%.The largest absolute deviation of maximum peak height(Sp)is 0.60μm with the maximum relative deviation 17.91%.The above result show that the 3D topography of the worn Ti6Al4V surface reconstructed from 2D optical image by SFS technique is comparable to that obtained from LSCM method,which proves the reliability of SFS technique in image processing of worn surfaces.
基金supported by the"Fundamental Research Funds for the Central Universities"(Grant No.30924010801).
文摘In this study,the potential application of shaped charge jets as transient antennas for electromagnetic signal transmission was explored and an electromagnetic pulse radiation system with a shaped charge jet as a transient antenna was proposed.During the research,crucial characteristics of the transient antenna formed by a shaped charge with a 30 mm diameter,such as resonant frequency,radiation pattern,and radiation efficiency,were evaluated.The typical shaped charge jet morphology was obtained based on the simulations,in which it could insight the dynamic behavior of the shaped charge jet selected.An equivalent model experiment was employed to test the radiation efficiency,and it showed that a shorting pin loading method could increase the relative bandwidth of the jet antenna to 32.8%,and the experimental results correlate with the theoretical predictions for half-wave dipole antennas reasonably well.Additionally,variations in the diameter of the shaped charge jet were found to affect the input impedance and impedance bandwidth,while the length of the jet influenced the resonant frequency of the antenna.This suggests that altering these parameters can achieve reconfigurability of the jet antenna.
基金supported by the Fund for BTNYGG(NYHXGG,2023AA102)the National Natural Science Foundation of China(32260510)+3 种基金the Key Project for Science,Technology Development of Shihezi city,Xinjiang Production and Construction Crops(2022NY01)Shihezi University high-level talent research project(RCZK202337)Science and Technology Major Project of the Department of Science and Technology of Xinjiang Uygur Autonomous region(2022A03004-1)the Key Programs for Science and Technology Development in Agricultural Field of Xinjiang Production and Construction Corps。
文摘Background Cotton is a significant crop for fiber production;however,seed shape-related traits have been less investigated in comparison to fiber quality.Comprehending the genetic foundation of traits associated with seed shape is crucial for improving the seed and fiber quality in cotton.Results A total of 238 cotton accessions were evaluated in four different environments over a period of two years.Traits including thousand grain weight(TGW),aspect ratio(AR),seed length,seed width,diameter,and roundness demonstrated high heritability and significant genetic variation,as indicated by phenotypic analysis.The association analysis involved 145 simple sequence repeats(SSR)markers and identified 50 loci significantly associated with six traits related to seed shape.The markers MON_DPL0504aa and BNL2535ba were identified as influencing multiple traits,including aspect ratio and thousand grain weight.Notably,markers such as HAU2588a and MUSS422aa had considerable influence on seed diameter and roundness.The identified markers represented an average phenotypic variance between 3.92%for seed length and 16.54%for TGW.Conclusions The research finds key loci for seed shape-related traits in cotton,providing significant potential for marker-assisted breeding.These findings establish a framework for breeding initiatives focused on enhancing seed quality,hence advancing the cotton production.
基金the financial support from the National Natural Science Foundation of China(Grant No.11572159)。
文摘The impact of high-velocity penetrators into liquid-filled containers can generate hydrodynamic ram effects,potentially causing catastrophic structural damage to the container.Previous studies have primarily focused on undeformed penetrators,such as fragments or bullets,with limited attention directed toward shaped charge jets.This study investigates the penetration characteristics of shaped charge jets impacting behind-armor liquid-filled containers,with particular emphasis on jet-liquid interactions.A theoretical penetration model incorporating material compressibility and jet stretching was developed based on the virtual origin theory.A high-speed imaging experimental system was designed to capture the jet motion within the container.The impact process was numerically reproduced using ANSYS/LSDYNA,and the effects of standoff and overmatch on jet penetration were analyzed.The results reveal that jet stretching induced by increased standoff enhances the penetration velocity of the jet.A proportional relationship between the stretching factor(λ)and the overmatch parameter(I)was identified,withλranging from approximately 1.22 to 1.38 times I across the studied standoff range(80-220 mm).The findings offer a basis for future studies on the pressure distribution in the liquid and the structural response of containers.
基金supported by the Ministère des Armées,and the Agence de l'Innovation de Défense(AID).
文摘An analysis of the interaction mechanisms between a Shaped Charge Jet(SCJ) and a single Moving Plate(MP) is proposed in this article using both experimental and numerical approaches. First, an experimental set-up is presented. Four collision tests have been performed: two tests in Backward Moving Plate(BMP) configuration, where the plate moves in opposition to jet, and two tests in Forward Moving Plate(FMP) configuration, where the plate moves alongside the jet. Based on the virtual origin approximation,a methodology(the Virtual Origin Method, VOM) is developed to extract quantities from the X-ray images, which serve as comparative data. γSPH simulations are carried out to complete the analysis, as they well capture the disturbance dynamics observed in the experiments. Based on these complementary experimental and numerical results, a new physical description is proposed through a detailed analysis of the interaction. It is shown that the SCJ/MP interaction is driven at first order by the contact geometry. Thus, BMP and FMP configurations do not generate the same disturbances because their local flow geometries are different. In the collision point frame of reference, the BMP flows in the same direction as the jet, causing its overall deflection. On the contrary, the FMP flow opposes that of the jet leading to an alternative creation of fragments and ligaments. An in-depth study, using the VOM shows that deflection angles, fragment-ligament creation frequencies, and deflection velocities evolve as the interaction progresses through slower jet elements.
基金Project(52409128)supported by the National Natural Science Foundation of ChinaProject(SDGZK2425)supported by the Opening Fund of State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China。
文摘The shape of underground chambers in deep mining varies due to their geological environment and intended use,which results in different failure modes under the influence of mining activities.However,the effect of chamber shape on the mechanism of structural integrity under dynamic load is still unclear.In this paper,granite samples with circular(C),rectangular(R),long ellipse(EL),and short ellipse(ES)holes were prepared.The dynamic mechanical response and cracking mechanism of granite were systematically analyzed using the split Hopkinson pressure bar(SHPB)test system and the hybrid finite and discrete element method(HFDEM).The results indicate that the dynamic strengths of granite with EL and ES represent the maximum and minimum values within the range of close strain rates,respectively.When EL granite is subjected to dynamic load,the axial stress concentration(in the load direction)is weak,and the transverse stress shows relative dispersion,which is the primary reason for its highest dynamic strength.The failure of granite with various holes primarily involves a tensile-shear mixed fracture,with relatively few pure typeⅡcracks.The chamber’s transverse span is the primary factor influencing the distribution range of the fracture area.
基金Foundation item: Project(2009AA04Z143) supported by the National High Technology Research and Development Program of ChinaProject (E2011203004) supported by Natural Science Foundation of Hebei Province, ChinaProjects(2011BAF15B03, 2011BAF15B02) supported by the National Science Plan of China
文摘A high-precision shape detecting system of cold rolling strip is developed to meet industrial application, which mainly consists of the shape detecting roller, the collecting ring, the digital signal processing （DSP） shape signal processing board and the shape control model. Based on the shape detecting principle, the shape detecting roller is designed with a new integral structure for improving the precision of shape detecting and avoiding scratching strip surface. Based on the DSP technology, the DSP shape signal processing circuit board is designed and embedded in the shape detecting system for the reliability and stability of shape signal processing. The shape detecting system was successfully used in Angang 1 250 mm HC 6-high reversible cold rolling mill. The precision of shape detecting is 0.2 I and the shape deviation is controlled within 6 1 after the close loop shape control is input.
