In this paper, a novel fuzzy sliding mode control（FSMC） guidance law with terminal constraints of miss distance, impact angle and acceleration is presented for a constant speed missile against the stationary or slow...In this paper, a novel fuzzy sliding mode control（FSMC） guidance law with terminal constraints of miss distance, impact angle and acceleration is presented for a constant speed missile against the stationary or slowly moving target. The proposed guidance law combines the sliding mode control algorithm with a fuzzy logic control scheme for the lag-free system and the first-order lag system. Through using Lyapunov stability theory, we prove the sliding surface converges to zero in finite time. Furthermore, considering the uncertain information and system disturbances, the guidance gains are on-line optimized by fuzzy logic technique. Numerical simulations are performed to demonstrate the performance of the FSMC guidance law and the results illustrate the validity and effectiveness of the proposed guidance law.展开更多
In order to solve kinematic redundancy problems of a hydraulic quadruped walking robot,which include leg dragging,sliding,impingement against the ground,an improved gait planning algorithm for this robot is proposed i...In order to solve kinematic redundancy problems of a hydraulic quadruped walking robot,which include leg dragging,sliding,impingement against the ground,an improved gait planning algorithm for this robot is proposed in this paper.First,the foot trajectory is designated as the improved composite cycloid foot trajectory.Second,the landing angle of each leg of the robot is controlled to satisfy friction cone to improve the stability performance of the robot.Then with the controllable landing angle of quadruped robot and a geometry method,the kinematic equation is derived in this paper.Finally,agait planning method of quadruped robot is proposed,a dynamic co-simulation is done with ADAMS and MATLAB,and practical experiments are conducted.The validity of the proposed algorithm is confirmed through the co-simulation and experimentation.The results show that the robot can avoid sliding,reduce impingement,and trot stably in trot gait.展开更多
The transition radiation of a charged particle crossing the interface of two media having a monatomic impurity layer is investigated. It is shown that at sliding angles of incidence of a particle on the boundary of th...The transition radiation of a charged particle crossing the interface of two media having a monatomic impurity layer is investigated. It is shown that at sliding angles of incidence of a particle on the boundary of the media, the transition radiation is mainly determined by the properties of the surface layer. The possibility of using transition radiation to study the surface of substances is discussed. In addition, due to the hard radiation present in space, this research may be important for the use of light monoatomic layers as a material for satellite antennas, “solar sails” and cover layers in a future space (interstellar) mission.展开更多
Twenty-nine species of butterflies were collected for observation and determination of the wing surfaces using a Scanning Electron Microscope(SEM).Butterfly wing surface displays structural anisotropism in micro-,subm...Twenty-nine species of butterflies were collected for observation and determination of the wing surfaces using a Scanning Electron Microscope(SEM).Butterfly wing surface displays structural anisotropism in micro-,submicro- and nano-scales.The scales on butterfly wing surface arrange like overlapping roof tiles.There are submicrometric vertical gibbosities,horizontal links,and nano-protuberances on the scales.First-incline-then-drip method and first-drip-then-incline method were used to measure the Sliding Angle(SA)of droplet on butterfly wing surface by an optical Contact Angle(CA)measuring system. Relatively smaller sliding angles indicate that the butterfly wing surface has fine self-cleaning property.Significantly different SAs in various directions indicate the anisotropic self-cleaning property of butterfly wing surface.The SAs on the butterfly wing surface without scales are remarkably larger than those with scales,which proves the crucial role of scales in determining the self-cleaning property.Butterfly wing surface is a template for design and fabrication ofbiomimetic materials and self-cleaning substrates.This work may offer insights into how to design directional self-cleaning coatings and anisotropic wetting surface.展开更多
A superhydrophobic Zn−Fe alloy coating was prepared on the surface of a reactive magnesium alloy using a simple,low-cost,eco-friendly method.Firstly,the Zn−Fe coating was obtained in a neutral glycerol Zn−Fe plating s...A superhydrophobic Zn−Fe alloy coating was prepared on the surface of a reactive magnesium alloy using a simple,low-cost,eco-friendly method.Firstly,the Zn−Fe coating was obtained in a neutral glycerol Zn−Fe plating solution,which is green,compositionally stable,and non-corrosive to the equipment.And then the superhydrophobic surface with a flower-like microstructure was obtained by grafting myristic acid onto the Zn−Fe coating via a chelation reaction.The water contact angle was>150°and the rolling angle was 3°−4°.The corrosion rate of the two groups of superhydrophobic magnesium alloy samples with electrodeposition time of 30 and 50 min,respectively,was reduced by about 87%compared to that of the bare magnesium alloy.The prepared superhydrophobic coatings exhibit high performance in self-cleaning,abrasion resistance,and corrosion resistance.展开更多
Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study th...Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study the effect ofb on the wettability of the rough surface, the effects of apparent contact angle （CA） and sliding angle （a） of the droplet on the rough surface were measured with the contact angle meter. The results show that the experimental values of CA well agree with the classical wetting theory and a decreases with the increase of b. Two drop shapes exist on the samples＇ surface, corresponding to the Cassie state and the Wenzel state respectively. The contact state in which a drop would settle depends typically on the size of b. On the role of gravitation, the irreversible transition of a drop from Cassie state to Wenzel state should occur at a certain space of the square pillars. Since the transition has implications on the application of super-hydrophobic rough surfaces, theoretically, the prediction of wetting state transition on square pillar array micro-structured surfaces provides an intuitionistic guidance for the design of steady superhydrophobic surfaces.展开更多
Previous studies highlighted the significance of optimizing the cutting blade for crop harvesting and size reduction.This study investigated the effect of blade sliding cutting angle and stem level on cutting energy o...Previous studies highlighted the significance of optimizing the cutting blade for crop harvesting and size reduction.This study investigated the effect of blade sliding cutting angle and stem level on cutting energy of single rice stem using a cutting apparatus that combined with texture analyzer.The cutting energy was determined for four blade angles.The results showed that the average cutting energy was the highest for cutting stem upper level and the lowest for cutting stem lower level.It was found that the peak cutting force per unit stem area decreased with blade sliding cutting angle increased.However,the least average cutting energy was 9.12 J/mm^(2) of 45°sliding angle when cutting without counter support blade and 32.3%less than that of 60°sliding angle.When cutting with counter support blade,the cutting energy per unit stem area varied from 6.57 to 12.54 J/mm 2 as the sliding angle varied from 0°to 60°,whereas the peak cutting force per unit stem area varied from 2.46 to 0.98 N/mm 2.It was concluded that the optimal sliding cutting angle was 45°without support blade and 30°with support blade,respectively.The experiments on rice stems in this study indicated that optimization of sliding cutting angle and stem level have a significant effect on cutting energy savings.Also this study emphasized the need to further investigate the effect of the case of more moisture content and cutting speed on the cutting energy to help in selection of optimum cutting speed and harvesting time.展开更多
The space effects of deep pit slope are analyzed by an elastic mechanics principle. The interaction among the critical slide angle, the friction coefficient, the cohesion, and the horizontal radius of the deep pits is...The space effects of deep pit slope are analyzed by an elastic mechanics principle. The interaction among the critical slide angle, the friction coefficient, the cohesion, and the horizontal radius of the deep pits is derived in this paper. It indicates that the deeper the pit is excavated, the greater the critical slide angle is. Both the theory for reducing stripping waste rock in deep pit and the approach to determining the configuration of the stable slope are developed from the interaction. The theory in this paper comprises the preceding principles of stability analysis of slopes and is suitable for analyzing that of deep pit.展开更多
Composite coatings or films with polytetrafluoroethylene(PTFE)are typically utilized to offer superhydrophobic surfaces.However,the superhydrophobic surfaces usually have limited durability and require complicated fab...Composite coatings or films with polytetrafluoroethylene(PTFE)are typically utilized to offer superhydrophobic surfaces.However,the superhydrophobic surfaces usually have limited durability and require complicated fabrication methods.Herein,we report the successful integration of PTFE with ZnO ceramics to achieve superhydrophobicity via a one-step sintering method,cold sintering process(CSP),at 300℃.(1–x)ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol%are densified with relative density of over 97%.Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases,which modulate surface morphology and surface energy of the ZnO–PTFE ceramic composites.For the 60 vol%ZnO–40 vol%PTFE ceramic composite,superhydrophobic properties are optimized with static water contact angles(WCAs)and sliding angles(SAs)of 162°and 7°,respectively.After abrading into various thicknesses(2.52,2.26,and 1.99 mm)and contaminating with graphite powders on the surface,WCA and SA are still maintained with a high level of 157°–160°and 7°–9.3°,respectively.This work indicates that CSP provides a promising pathway to integrate polymers with ceramics to realize stable superhydrophobicity.展开更多
基金supported by the National Natural Science Foundation of China(6130422461305018+1 种基金61472423)the National Advanced Research Project of China(51301010206)
文摘In this paper, a novel fuzzy sliding mode control（FSMC） guidance law with terminal constraints of miss distance, impact angle and acceleration is presented for a constant speed missile against the stationary or slowly moving target. The proposed guidance law combines the sliding mode control algorithm with a fuzzy logic control scheme for the lag-free system and the first-order lag system. Through using Lyapunov stability theory, we prove the sliding surface converges to zero in finite time. Furthermore, considering the uncertain information and system disturbances, the guidance gains are on-line optimized by fuzzy logic technique. Numerical simulations are performed to demonstrate the performance of the FSMC guidance law and the results illustrate the validity and effectiveness of the proposed guidance law.
基金Supported by National High Technology Research and Development Program of China(863 Program)(2011AA041002)
文摘In order to solve kinematic redundancy problems of a hydraulic quadruped walking robot,which include leg dragging,sliding,impingement against the ground,an improved gait planning algorithm for this robot is proposed in this paper.First,the foot trajectory is designated as the improved composite cycloid foot trajectory.Second,the landing angle of each leg of the robot is controlled to satisfy friction cone to improve the stability performance of the robot.Then with the controllable landing angle of quadruped robot and a geometry method,the kinematic equation is derived in this paper.Finally,agait planning method of quadruped robot is proposed,a dynamic co-simulation is done with ADAMS and MATLAB,and practical experiments are conducted.The validity of the proposed algorithm is confirmed through the co-simulation and experimentation.The results show that the robot can avoid sliding,reduce impingement,and trot stably in trot gait.
文摘The transition radiation of a charged particle crossing the interface of two media having a monatomic impurity layer is investigated. It is shown that at sliding angles of incidence of a particle on the boundary of the media, the transition radiation is mainly determined by the properties of the surface layer. The possibility of using transition radiation to study the surface of substances is discussed. In addition, due to the hard radiation present in space, this research may be important for the use of light monoatomic layers as a material for satellite antennas, “solar sails” and cover layers in a future space (interstellar) mission.
基金supported by the National Natural Science Foundation of China (Grant No. 50635030)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20040183048)the Project Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry
文摘Twenty-nine species of butterflies were collected for observation and determination of the wing surfaces using a Scanning Electron Microscope(SEM).Butterfly wing surface displays structural anisotropism in micro-,submicro- and nano-scales.The scales on butterfly wing surface arrange like overlapping roof tiles.There are submicrometric vertical gibbosities,horizontal links,and nano-protuberances on the scales.First-incline-then-drip method and first-drip-then-incline method were used to measure the Sliding Angle(SA)of droplet on butterfly wing surface by an optical Contact Angle(CA)measuring system. Relatively smaller sliding angles indicate that the butterfly wing surface has fine self-cleaning property.Significantly different SAs in various directions indicate the anisotropic self-cleaning property of butterfly wing surface.The SAs on the butterfly wing surface without scales are remarkably larger than those with scales,which proves the crucial role of scales in determining the self-cleaning property.Butterfly wing surface is a template for design and fabrication ofbiomimetic materials and self-cleaning substrates.This work may offer insights into how to design directional self-cleaning coatings and anisotropic wetting surface.
基金supports from the National Natural Science Foundation of China(No.22178242).
文摘A superhydrophobic Zn−Fe alloy coating was prepared on the surface of a reactive magnesium alloy using a simple,low-cost,eco-friendly method.Firstly,the Zn−Fe coating was obtained in a neutral glycerol Zn−Fe plating solution,which is green,compositionally stable,and non-corrosive to the equipment.And then the superhydrophobic surface with a flower-like microstructure was obtained by grafting myristic acid onto the Zn−Fe coating via a chelation reaction.The water contact angle was>150°and the rolling angle was 3°−4°.The corrosion rate of the two groups of superhydrophobic magnesium alloy samples with electrodeposition time of 30 and 50 min,respectively,was reduced by about 87%compared to that of the bare magnesium alloy.The prepared superhydrophobic coatings exhibit high performance in self-cleaning,abrasion resistance,and corrosion resistance.
基金Project(50435030) supported by the National Natural Science foundation of ChinaProject supported by the Program for New Century Excellent Talents in Chinese University Project(GZ080010) supported by the Open Research Fund Program of Jiangsu Province Key Laboratory for Photon Manufacturing Science and Technology
文摘Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study the effect ofb on the wettability of the rough surface, the effects of apparent contact angle （CA） and sliding angle （a） of the droplet on the rough surface were measured with the contact angle meter. The results show that the experimental values of CA well agree with the classical wetting theory and a decreases with the increase of b. Two drop shapes exist on the samples＇ surface, corresponding to the Cassie state and the Wenzel state respectively. The contact state in which a drop would settle depends typically on the size of b. On the role of gravitation, the irreversible transition of a drop from Cassie state to Wenzel state should occur at a certain space of the square pillars. Since the transition has implications on the application of super-hydrophobic rough surfaces, theoretically, the prediction of wetting state transition on square pillar array micro-structured surfaces provides an intuitionistic guidance for the design of steady superhydrophobic surfaces.
基金This study was funded by the Chinese Government through the Anhui Agricultural University within a program titled“The National Key Research and Development Program of China(No.2017YFD0301303)”the China’s Ministry of Agriculture through the China Agricultural University with a program titled“China’s Ministry of Agriculture,Agricultural Public Welfare Industry Special Project(No.201503136)”.
文摘Previous studies highlighted the significance of optimizing the cutting blade for crop harvesting and size reduction.This study investigated the effect of blade sliding cutting angle and stem level on cutting energy of single rice stem using a cutting apparatus that combined with texture analyzer.The cutting energy was determined for four blade angles.The results showed that the average cutting energy was the highest for cutting stem upper level and the lowest for cutting stem lower level.It was found that the peak cutting force per unit stem area decreased with blade sliding cutting angle increased.However,the least average cutting energy was 9.12 J/mm^(2) of 45°sliding angle when cutting without counter support blade and 32.3%less than that of 60°sliding angle.When cutting with counter support blade,the cutting energy per unit stem area varied from 6.57 to 12.54 J/mm 2 as the sliding angle varied from 0°to 60°,whereas the peak cutting force per unit stem area varied from 2.46 to 0.98 N/mm 2.It was concluded that the optimal sliding cutting angle was 45°without support blade and 30°with support blade,respectively.The experiments on rice stems in this study indicated that optimization of sliding cutting angle and stem level have a significant effect on cutting energy savings.Also this study emphasized the need to further investigate the effect of the case of more moisture content and cutting speed on the cutting energy to help in selection of optimum cutting speed and harvesting time.
文摘The space effects of deep pit slope are analyzed by an elastic mechanics principle. The interaction among the critical slide angle, the friction coefficient, the cohesion, and the horizontal radius of the deep pits is derived in this paper. It indicates that the deeper the pit is excavated, the greater the critical slide angle is. Both the theory for reducing stripping waste rock in deep pit and the approach to determining the configuration of the stable slope are developed from the interaction. The theory in this paper comprises the preceding principles of stability analysis of slopes and is suitable for analyzing that of deep pit.
基金The authors acknowledge the support from the funding of the National Natural Science Foundation of China(Grant No.51877016)the Fok Ying-Tong Education Foundation,China(Grant No.171050)Science and Technology Project of State Grid Co.,Ltd.,China(Grant No.5500-202399372A-2-2-ZB).
文摘Composite coatings or films with polytetrafluoroethylene(PTFE)are typically utilized to offer superhydrophobic surfaces.However,the superhydrophobic surfaces usually have limited durability and require complicated fabrication methods.Herein,we report the successful integration of PTFE with ZnO ceramics to achieve superhydrophobicity via a one-step sintering method,cold sintering process(CSP),at 300℃.(1–x)ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol%are densified with relative density of over 97%.Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases,which modulate surface morphology and surface energy of the ZnO–PTFE ceramic composites.For the 60 vol%ZnO–40 vol%PTFE ceramic composite,superhydrophobic properties are optimized with static water contact angles(WCAs)and sliding angles(SAs)of 162°and 7°,respectively.After abrading into various thicknesses(2.52,2.26,and 1.99 mm)and contaminating with graphite powders on the surface,WCA and SA are still maintained with a high level of 157°–160°and 7°–9.3°,respectively.This work indicates that CSP provides a promising pathway to integrate polymers with ceramics to realize stable superhydrophobicity.
