The non-scaling effect on the penetration depth of rigid projectiles is an important issue that must be considered when extending the results of scaled experiments to prototype scenes.In this study,the evolution of th...The non-scaling effect on the penetration depth of rigid projectiles is an important issue that must be considered when extending the results of scaled experiments to prototype scenes.In this study,the evolution of the stress and strain of the target under penetration was analyzed.Expressions for the penetration resistance and penetration depth were obtained based on the conservation equation and continuity condition of the target.The penetration coefficients that characterize the nose shape,target resistance,and non-scaling effect were defined.Simplified calculation methods for the coefficients within the range of rigid projectile penetration were developed.Two methods for estimating the target parameters are proposed.The results show that the non-scaling effect is related to the failure process of the target and depends on the ratio of cavity radius to comminuted region radius.The nose shape coefficient can be approximated as a linear function of the length-to-diameter ratio of the nose.The noseshape coefficient of a flat-nosed projectile is 0.57.The caliber coefficient is related to the projectile diameter and reflects the non-scaling effect,which increases with the projectile diameter.A practical formula for calculating the penetration depth of rigid projectiles considering the non-scaling effect is also proposed.This formula is in good agreement with penetration experiments on rock and concrete.展开更多
Recently,multi-pass caliber rolling has been shown to be effective for Mg alloys.This study investigated the effect of subsequent annealing on the mechanical properties of a caliber-rolled AZ31 Mg alloy to modulate th...Recently,multi-pass caliber rolling has been shown to be effective for Mg alloys.This study investigated the effect of subsequent annealing on the mechanical properties of a caliber-rolled AZ31 Mg alloy to modulate the strength-ductility relationship.This annealing gave rise to different trends in mechanical properties depending on the temperature regime.Low-temperature annealing(T≤473 K)exhibited a typical trade-off relationship,where an increase in annealing temperature resulted in increased ductility but decreased strength and hardness.Such a heat treatment did not degrade the high strength-ductility balance of the caliber-rolled alloy,suggesting that the mechanical properties could be tailored for different potential applications.In contrast,high-temperature annealing(T>473 K)caused a simultaneous deterioration in strength,hardness,and ductility with increasing annealing temperature.These differences are discussed in terms of the varying microstructural features under the different investigated annealing regimes.展开更多
Compact hot extrusion(CHE) process of heavy caliber thick-wall pipe is a new material-saving production process. In order to reveal the optimum hot extrusion parameters in CHE process, the e ects of the extrusion para...Compact hot extrusion(CHE) process of heavy caliber thick-wall pipe is a new material-saving production process. In order to reveal the optimum hot extrusion parameters in CHE process, the e ects of the extrusion parameters on the microstructural evolution are investigated systematically. The metadynamic recrystallization(MDRX) kinetic models and grain size models of as-cast P91 steel are established for the first time according to the hot compression tests performed on the Gleeble-3500 thermal-simulation machine. Then a thermal-mechanical and micro-macro coupled hot extrusion finite element(FE) model is established and further developed in DEFORM software. The results indicated that the grain size of the extruded pipe increases with the increasing of initial temperature and extrusion speed, decreases when extrusion ratio increases. Moreover, the grain size is more sensitive to the initial temperature and the extrusion ratio. The optimum hot extrusion parameters are including that, the initial extrusion temperature of 1250 °C, the extrusion ratio of 9 and the extrusion speed of 50 mm/s. Furthermore, in order to verify the simulation precisions, hot extrusion experiment verification on the heavy caliber thick-wall pipe is carried out on the 500 MN vertical hot extrusion equipment. The load–displacement curve of the extrusion process and the grain sizes of the middle part extruded pipe are in good accuracy with the simulation results, which confirms that the hot extrusion FE models of as-cast P91 steel could estimate the hot extrusion behaviors. The proposed hot extrusion FE model can be used to guide the industrial production research of CHE process.展开更多
Mge3Ale1Zn(AZ31)alloy was caliber rolled isothermally in the temperature range of 250e450C to develop fine grains of 3.6e12.5 mm.The stressestrain curves obtained from tensile tests at room temperature were found to ...Mge3Ale1Zn(AZ31)alloy was caliber rolled isothermally in the temperature range of 250e450C to develop fine grains of 3.6e12.5 mm.The stressestrain curves obtained from tensile tests at room temperature were found to vary with the temperature employed in caliber rolling.Maximum tensile strength of 290 MPa and ductility of 13.5%were obtained upon caliber rolling at 300C as compared to 188 MPa and 15.2%,respectively,in the mill-rolled condition.The variations in tensile properties are explained by the concomitant grain size,texture and twins obtained as a function of caliber rolling temperature.展开更多
Magnesium alloy AZ31 was caliber rolled at different temperatures viz.523K,573K,623K,673K and 723K imposing a total cumulative reduction of 92%and a cumulative strain of 2.6.The associated microstructure and texture e...Magnesium alloy AZ31 was caliber rolled at different temperatures viz.523K,573K,623K,673K and 723K imposing a total cumulative reduction of 92%and a cumulative strain of 2.6.The associated microstructure and texture evolution were studied using Electron Back Scattered Diffraction(EBSD)and X-ray macro-texture observations respectively.Grain refinement was observed in all the caliber rolled bars indicating the occurrence of dynamic recrystallization.Asymmetry parameter and texture index were used to study the evolution of texture.Near doubling of the yield strength at room temperature was observed by caliber rolling at a temperature of 573K.The improvement in mechanical properties was explained on the basis of the fine grain microstructures and suitable development of crystallographic texture.Based on the present study,warm caliber rolling can be used as a good production method for obtaining long bars of high strength magnesium alloy AZ31.展开更多
A multi-pass caliber rolling has attracted attentions as an alternative to severe plastic deformation processes.The present study enhanced strength and ductility of AZ31 Mg alloy simultaneously through the application...A multi-pass caliber rolling has attracted attentions as an alternative to severe plastic deformation processes.The present study enhanced strength and ductility of AZ31 Mg alloy simultaneously through the application of caliber rolling.The improving trends in tensile properties were interpreted with various caliber-rolling strains.The oval/circular-shaped calibers imposed a high plastic strain at the center of crosssection,leading to effective grain refinement to submicron scale.This work also confirmed the texture randomizing effect of caliber rolling.Such microstructural evolutions gave rise to the fabrication of high-strength material.Moreover,the caliber-rolled AZ31 Mg alloys exhibited an improvement in ductility as compared to the as-received sheet-rolled material.This was discussed in terms of activation of non-basal slip systems and suppression of mechanical twinning.This study successfully proved the possibility of caliber rolling to produce a bulk Mg rod with enhanced tensile properties.展开更多
AIM：To evaluate the effect of strabismus surgery on retinal vessels calibers with digital color fundus photographs.METHODS：Two hundred consecutive strabismus patients underwent surgery,and 118 patients（female/male,...AIM：To evaluate the effect of strabismus surgery on retinal vessels calibers with digital color fundus photographs.METHODS：Two hundred consecutive strabismus patients underwent surgery,and 118 patients（female/male,55/63） who finished 6-month follow-up were finally included in this study.Optic disc-centered digital color fundus photographs of both eyes of all patients were taken prior to surgery and 6mo post surgery.The retinal vascular caliber of 116 operated eyes were measured using the computer program IVAN.The operated eyes were divided into 3 groups according to the surgical methods,recession of one muscle,one muscle recession and one muscle folding,one muscle resection and one muscle recession.The effect of number of altered muscles on retinal vessels was analyzed using statistic software SPSS 16.0.RESULTS：The mean age was 12.4±8.6y.Averaged central retinal artery equivalent（CRAE） of all patients was 120.31 ±23.02 μm preoperatively,and 122.87 ±15.93 μm six months after surgery.Averaged central retinal vein equivalent（CRVE） was 171.11 ±31.73 μm preoperatively and175.02±21.00 μm postoperatively.There was no significant difference of averaged CRAE（P=0.22） or CRVE（P=0.19）before and after operation.Averaged arteriole to venule ratio（AVR） was 0.71 ±0.07 before surgery and 0.70±0.07 after surgery.Comparison of preoperative and postoperative retinal vessels calibers among different surgical groups did not show significant differences.Also,there was no advantage of rectus muscle folding to muscle resection.CONCLUSION：Up to 6mo after strabismus surgery,the retinal vascular calibers were not altered.No more than two muscles in one surgery are safe for retinal perfusion.展开更多
The effects of reduction in area(RA)per pass during caliber rolling on microstructure and strain distribution of twinninginduced plasticity steel have been investigated to find solutions to make a more homogeneous mat...The effects of reduction in area(RA)per pass during caliber rolling on microstructure and strain distribution of twinninginduced plasticity steel have been investigated to find solutions to make a more homogeneous material along the radial direction for wire rod applications.The steel wires subjected to an average RA per pass of 2.5%(skin pass caliber rolling)and 10.0%(conventional caliber rolling)were analyzed.The skin pass caliber-rolled wire was characterized as a duplex fiber texture of major<111>and minor<100>.and the textures were almost same at/between center and surface area,which is totally different from those of conventional caliber rolling and wire drawing.The skin pass caliber rolling led to more homogeneous microstructure and mechanical properties along the radial direction in comparison with the conventional caliber rolling and wire drawing due to the more homogeneous Hall-Petch hardening,dislocation hardening,and texture behavior with area,resulting in higher formability.展开更多
In the Retiro, ＂El Lucero＂ county, Maule, VII Region of Chile, an application of a marine algae extract known as Ascophilliurn nodosum, whose commercial name is Ekologik~, was evaluated by applying it to the whole f...In the Retiro, ＂El Lucero＂ county, Maule, VII Region of Chile, an application of a marine algae extract known as Ascophilliurn nodosum, whose commercial name is Ekologik~, was evaluated by applying it to the whole foliage in order to evaluate the impact on total weight, average weight, equatorial diameter and soluble solids in cv. O＇Neal blueberries harvested in a three-year old orchard having a plantation density of 3,333 plants hal. The marine algae extract was applied in three phenologic phases： full bloom, fruit set and fruit color break. Four treatments were conducted： To, application of pure water （without the product）; T1, a 280 mL ha1 dose per application; T2, a 140 mL ha^-1 dose, equivalent to 50% of the treatment dose T1; and T3, a 420 mL ha^-1 dose, equivalent to a 50% extra than the treatment dose T1. The experimental design comprised sutb-sampling blocks with three repetitions of three uniform and healthy plants per treatment. Regarding the total and average fruit weight, they did not show significant statistical differences, but an increase in the average weight of fruits treated with the aforementioned product was observed. For parameters such as equatorial diameter, caliper and soluble solids of harvested fruit, the product caused a statistically significant increase. T3 was found to be the best treatment with a 15% weight, increasing taste, sugar amount, size and weight of the harvested fruits.展开更多
In this paper,a novel large caliber machine gun was taken as the research object to analyze the floating technique based on the principle of fixed-point constraint and secondary counter-recoil.A rigid-flexible couplin...In this paper,a novel large caliber machine gun was taken as the research object to analyze the floating technique based on the principle of fixed-point constraint and secondary counter-recoil.A rigid-flexible coupling multi-body dynamic model of the large caliber machine gun with muzzle brake based on floating principle was established,in which the influence of soil and human body was taken into account.The dynamic simulation was conducted and then the results were compared with the corresponding experimental data The dynamic characteristics of the machine gun with or without floating technique were analyzed to indicate the influence of floating technique upon the performance of the gun.Furthermore,the rigid-flexible coupling dynamic models with five different firing angles was constructed to study the influence caused by the angles.The results indicated that the floating mechanism could reduce the recoil effectively and improve the operational performance of this novel large caliber machine gun.展开更多
This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 ...This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio(PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.展开更多
This study investigates the influence of varying rolling reduction on the evolution of microstructure and mechanical properties of Mg–10Gd(in wt%)alloys by caliber rolling(CR).By increasing the rolling reduction from...This study investigates the influence of varying rolling reduction on the evolution of microstructure and mechanical properties of Mg–10Gd(in wt%)alloys by caliber rolling(CR).By increasing the rolling reduction from 45%to 65%,a uniform bimodal structure is obtained in which coarse grains(CGs)larger than 10μm are surrounded by fine grains(FGs).The Mg–Gd alloy subjected to 65%reduction exhibits superior mechanical properties,i.e.yield strength(YS)of~424 MPa,ultimate tensile strength(UTS)of~500 MPa and elongation(El.)of~3.3%.The synergistic improvement in strength and ductility is primarily attributed to the combined effects of low-angle grain boundary(LAGB)strengthening,precipitation strengthening,and the coordinated deformation exhibited by the bimodal structure.In addition,caliber rolling also provides a novel approach for the design of Mg alloys with uniform bimodal structures that exhibit both high strength and ductility.展开更多
The medium -large caliber naval gun is still playing an important role in modern war. The development of highly automatic Shell Raising and Feeding System (SRFS) in the world has been briefly outlined. Several typical...The medium -large caliber naval gun is still playing an important role in modern war. The development of highly automatic Shell Raising and Feeding System (SRFS) in the world has been briefly outlined. Several typical SRFS of medium-large caliber naval guns have been analyzed. A re-design of the system is introduced, in which systematic design method has been used to demonstrate its feasibility. The design goal of the system is to realize rapid shell feeding, with application to many types of shells, quick change of shell types , accurate and reliable feeding operation, simple mechanical structure and easy realization of shell withdrawing.展开更多
About Science Bulletin Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of Ch...About Science Bulletin Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields on the basis of its originality,scientific significance and whether it is of general interest.展开更多
Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a...Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.展开更多
Science Bulletin(Sci.Butl.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a...Science Bulletin(Sci.Butl.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed rescarch in a broad range of natural sciences and high-tech fields based on its originality.scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.展开更多
Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a...Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.展开更多
Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a...Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.展开更多
Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a...Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.展开更多
Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a...Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.展开更多
基金the National Natural Science Foundation of China(Grant Nos.52422808,52378401)to provide funds for this research。
文摘The non-scaling effect on the penetration depth of rigid projectiles is an important issue that must be considered when extending the results of scaled experiments to prototype scenes.In this study,the evolution of the stress and strain of the target under penetration was analyzed.Expressions for the penetration resistance and penetration depth were obtained based on the conservation equation and continuity condition of the target.The penetration coefficients that characterize the nose shape,target resistance,and non-scaling effect were defined.Simplified calculation methods for the coefficients within the range of rigid projectile penetration were developed.Two methods for estimating the target parameters are proposed.The results show that the non-scaling effect is related to the failure process of the target and depends on the ratio of cavity radius to comminuted region radius.The nose shape coefficient can be approximated as a linear function of the length-to-diameter ratio of the nose.The noseshape coefficient of a flat-nosed projectile is 0.57.The caliber coefficient is related to the projectile diameter and reflects the non-scaling effect,which increases with the projectile diameter.A practical formula for calculating the penetration depth of rigid projectiles considering the non-scaling effect is also proposed.This formula is in good agreement with penetration experiments on rock and concrete.
基金This work was supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)through GCRC-SOP(No.2011-0030013).
文摘Recently,multi-pass caliber rolling has been shown to be effective for Mg alloys.This study investigated the effect of subsequent annealing on the mechanical properties of a caliber-rolled AZ31 Mg alloy to modulate the strength-ductility relationship.This annealing gave rise to different trends in mechanical properties depending on the temperature regime.Low-temperature annealing(T≤473 K)exhibited a typical trade-off relationship,where an increase in annealing temperature resulted in increased ductility but decreased strength and hardness.Such a heat treatment did not degrade the high strength-ductility balance of the caliber-rolled alloy,suggesting that the mechanical properties could be tailored for different potential applications.In contrast,high-temperature annealing(T>473 K)caused a simultaneous deterioration in strength,hardness,and ductility with increasing annealing temperature.These differences are discussed in terms of the varying microstructural features under the different investigated annealing regimes.
基金Supported by National Natural Science Foundation of China(Grant Nos.51675361,51135007)Shanxi Scholarship Council of China(Grant Nos.2015-086,2016-096)Shanxi Provincial Key Research and Development Program of China(Grant No.03012015004)
文摘Compact hot extrusion(CHE) process of heavy caliber thick-wall pipe is a new material-saving production process. In order to reveal the optimum hot extrusion parameters in CHE process, the e ects of the extrusion parameters on the microstructural evolution are investigated systematically. The metadynamic recrystallization(MDRX) kinetic models and grain size models of as-cast P91 steel are established for the first time according to the hot compression tests performed on the Gleeble-3500 thermal-simulation machine. Then a thermal-mechanical and micro-macro coupled hot extrusion finite element(FE) model is established and further developed in DEFORM software. The results indicated that the grain size of the extruded pipe increases with the increasing of initial temperature and extrusion speed, decreases when extrusion ratio increases. Moreover, the grain size is more sensitive to the initial temperature and the extrusion ratio. The optimum hot extrusion parameters are including that, the initial extrusion temperature of 1250 °C, the extrusion ratio of 9 and the extrusion speed of 50 mm/s. Furthermore, in order to verify the simulation precisions, hot extrusion experiment verification on the heavy caliber thick-wall pipe is carried out on the 500 MN vertical hot extrusion equipment. The load–displacement curve of the extrusion process and the grain sizes of the middle part extruded pipe are in good accuracy with the simulation results, which confirms that the hot extrusion FE models of as-cast P91 steel could estimate the hot extrusion behaviors. The proposed hot extrusion FE model can be used to guide the industrial production research of CHE process.
基金We express our thanks to DST for funding under FIST program SR/FST/ETII e 054/2000 for purchase of Universal Testing Machine and high temperature test facility.
文摘Mge3Ale1Zn(AZ31)alloy was caliber rolled isothermally in the temperature range of 250e450C to develop fine grains of 3.6e12.5 mm.The stressestrain curves obtained from tensile tests at room temperature were found to vary with the temperature employed in caliber rolling.Maximum tensile strength of 290 MPa and ductility of 13.5%were obtained upon caliber rolling at 300C as compared to 188 MPa and 15.2%,respectively,in the mill-rolled condition.The variations in tensile properties are explained by the concomitant grain size,texture and twins obtained as a function of caliber rolling temperature.
文摘Magnesium alloy AZ31 was caliber rolled at different temperatures viz.523K,573K,623K,673K and 723K imposing a total cumulative reduction of 92%and a cumulative strain of 2.6.The associated microstructure and texture evolution were studied using Electron Back Scattered Diffraction(EBSD)and X-ray macro-texture observations respectively.Grain refinement was observed in all the caliber rolled bars indicating the occurrence of dynamic recrystallization.Asymmetry parameter and texture index were used to study the evolution of texture.Near doubling of the yield strength at room temperature was observed by caliber rolling at a temperature of 573K.The improvement in mechanical properties was explained on the basis of the fine grain microstructures and suitable development of crystallographic texture.Based on the present study,warm caliber rolling can be used as a good production method for obtaining long bars of high strength magnesium alloy AZ31.
基金This work was supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2018R1C1B6002068).
文摘A multi-pass caliber rolling has attracted attentions as an alternative to severe plastic deformation processes.The present study enhanced strength and ductility of AZ31 Mg alloy simultaneously through the application of caliber rolling.The improving trends in tensile properties were interpreted with various caliber-rolling strains.The oval/circular-shaped calibers imposed a high plastic strain at the center of crosssection,leading to effective grain refinement to submicron scale.This work also confirmed the texture randomizing effect of caliber rolling.Such microstructural evolutions gave rise to the fabrication of high-strength material.Moreover,the caliber-rolled AZ31 Mg alloys exhibited an improvement in ductility as compared to the as-received sheet-rolled material.This was discussed in terms of activation of non-basal slip systems and suppression of mechanical twinning.This study successfully proved the possibility of caliber rolling to produce a bulk Mg rod with enhanced tensile properties.
基金Supported by Funds for Clinical-Basic Research Cooperation of Capital Medical University(No.14JL04)Beijing Municipal Science&Technology Commission(No.Z141107002514030)
文摘AIM：To evaluate the effect of strabismus surgery on retinal vessels calibers with digital color fundus photographs.METHODS：Two hundred consecutive strabismus patients underwent surgery,and 118 patients（female/male,55/63） who finished 6-month follow-up were finally included in this study.Optic disc-centered digital color fundus photographs of both eyes of all patients were taken prior to surgery and 6mo post surgery.The retinal vascular caliber of 116 operated eyes were measured using the computer program IVAN.The operated eyes were divided into 3 groups according to the surgical methods,recession of one muscle,one muscle recession and one muscle folding,one muscle resection and one muscle recession.The effect of number of altered muscles on retinal vessels was analyzed using statistic software SPSS 16.0.RESULTS：The mean age was 12.4±8.6y.Averaged central retinal artery equivalent（CRAE） of all patients was 120.31 ±23.02 μm preoperatively,and 122.87 ±15.93 μm six months after surgery.Averaged central retinal vein equivalent（CRVE） was 171.11 ±31.73 μm preoperatively and175.02±21.00 μm postoperatively.There was no significant difference of averaged CRAE（P=0.22） or CRVE（P=0.19）before and after operation.Averaged arteriole to venule ratio（AVR） was 0.71 ±0.07 before surgery and 0.70±0.07 after surgery.Comparison of preoperative and postoperative retinal vessels calibers among different surgical groups did not show significant differences.Also,there was no advantage of rectus muscle folding to muscle resection.CONCLUSION：Up to 6mo after strabismus surgery,the retinal vascular calibers were not altered.No more than two muscles in one surgery are safe for retinal perfusion.
基金This research was supported by National Research Foundation of Korea(NRF-2018R1 DIA1B07050103)the Tongmyong University Research Grants 2018(2018A016-1).
文摘The effects of reduction in area(RA)per pass during caliber rolling on microstructure and strain distribution of twinninginduced plasticity steel have been investigated to find solutions to make a more homogeneous material along the radial direction for wire rod applications.The steel wires subjected to an average RA per pass of 2.5%(skin pass caliber rolling)and 10.0%(conventional caliber rolling)were analyzed.The skin pass caliber-rolled wire was characterized as a duplex fiber texture of major<111>and minor<100>.and the textures were almost same at/between center and surface area,which is totally different from those of conventional caliber rolling and wire drawing.The skin pass caliber rolling led to more homogeneous microstructure and mechanical properties along the radial direction in comparison with the conventional caliber rolling and wire drawing due to the more homogeneous Hall-Petch hardening,dislocation hardening,and texture behavior with area,resulting in higher formability.
文摘In the Retiro, ＂El Lucero＂ county, Maule, VII Region of Chile, an application of a marine algae extract known as Ascophilliurn nodosum, whose commercial name is Ekologik~, was evaluated by applying it to the whole foliage in order to evaluate the impact on total weight, average weight, equatorial diameter and soluble solids in cv. O＇Neal blueberries harvested in a three-year old orchard having a plantation density of 3,333 plants hal. The marine algae extract was applied in three phenologic phases： full bloom, fruit set and fruit color break. Four treatments were conducted： To, application of pure water （without the product）; T1, a 280 mL ha1 dose per application; T2, a 140 mL ha^-1 dose, equivalent to 50% of the treatment dose T1; and T3, a 420 mL ha^-1 dose, equivalent to a 50% extra than the treatment dose T1. The experimental design comprised sutb-sampling blocks with three repetitions of three uniform and healthy plants per treatment. Regarding the total and average fruit weight, they did not show significant statistical differences, but an increase in the average weight of fruits treated with the aforementioned product was observed. For parameters such as equatorial diameter, caliper and soluble solids of harvested fruit, the product caused a statistically significant increase. T3 was found to be the best treatment with a 15% weight, increasing taste, sugar amount, size and weight of the harvested fruits.
基金supported by the National Natural Science Foundation of China under Grant No.11802138China Postdoctoral Science Foundation under Grant No.2018T110503the Fundamental Research Funds for the Central Universities under Grant No.30918011302
文摘In this paper,a novel large caliber machine gun was taken as the research object to analyze the floating technique based on the principle of fixed-point constraint and secondary counter-recoil.A rigid-flexible coupling multi-body dynamic model of the large caliber machine gun with muzzle brake based on floating principle was established,in which the influence of soil and human body was taken into account.The dynamic simulation was conducted and then the results were compared with the corresponding experimental data The dynamic characteristics of the machine gun with or without floating technique were analyzed to indicate the influence of floating technique upon the performance of the gun.Furthermore,the rigid-flexible coupling dynamic models with five different firing angles was constructed to study the influence caused by the angles.The results indicated that the floating mechanism could reduce the recoil effectively and improve the operational performance of this novel large caliber machine gun.
文摘This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio(PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.
基金financial support from the National Natural Science Foundation of China(51701060,52001106)Hebei Province(E2022202158),the foundation of the Strengthening Program(2019-JCJQ-142-00)。
文摘This study investigates the influence of varying rolling reduction on the evolution of microstructure and mechanical properties of Mg–10Gd(in wt%)alloys by caliber rolling(CR).By increasing the rolling reduction from 45%to 65%,a uniform bimodal structure is obtained in which coarse grains(CGs)larger than 10μm are surrounded by fine grains(FGs).The Mg–Gd alloy subjected to 65%reduction exhibits superior mechanical properties,i.e.yield strength(YS)of~424 MPa,ultimate tensile strength(UTS)of~500 MPa and elongation(El.)of~3.3%.The synergistic improvement in strength and ductility is primarily attributed to the combined effects of low-angle grain boundary(LAGB)strengthening,precipitation strengthening,and the coordinated deformation exhibited by the bimodal structure.In addition,caliber rolling also provides a novel approach for the design of Mg alloys with uniform bimodal structures that exhibit both high strength and ductility.
文摘The medium -large caliber naval gun is still playing an important role in modern war. The development of highly automatic Shell Raising and Feeding System (SRFS) in the world has been briefly outlined. Several typical SRFS of medium-large caliber naval guns have been analyzed. A re-design of the system is introduced, in which systematic design method has been used to demonstrate its feasibility. The design goal of the system is to realize rapid shell feeding, with application to many types of shells, quick change of shell types , accurate and reliable feeding operation, simple mechanical structure and easy realization of shell withdrawing.
文摘About Science Bulletin Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields on the basis of its originality,scientific significance and whether it is of general interest.
文摘Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.
文摘Science Bulletin(Sci.Butl.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed rescarch in a broad range of natural sciences and high-tech fields based on its originality.scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.
文摘Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.
文摘Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.
文摘Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.
文摘Science Bulletin(Sci.Bull.)is a multidisciplinary academic journal supervised by the Chinese Academy of Sciences(CAS)and co-sponsored by the CAS and the National Natural Science Foundation of China(NSFC).Sci.Bull.is a semi-monthly international journal publishing high-caliber peer-reviewed research in a broad range of natural sciences and high-tech fields based on its originality,scientific significance,and whether it is of general interest.In addition,we are committed to serving the scientific community with immediate,authoritative news and valuable insights into upcoming trends around the globe.
