During the operation of the rice combine harvester,the fuselage tilts due to the tilt and unevenness of the ground affect its maneuverability and operational reliability.Aiming at the problem of leveling due to the ti...During the operation of the rice combine harvester,the fuselage tilts due to the tilt and unevenness of the ground affect its maneuverability and operational reliability.Aiming at the problem of leveling due to the tilt of the field surface,this research developed an innovative dual-parallelogram chassis lifting mechanism for rice harvesters designed a hydraulic system to adjust the chassis height by extending the cylinder.Using Adams simulation software,a detailed model of the lifting chassis was constructed to analyze its performance,revealing a direct correlation between the hydraulic cylinder extension and chassis elevation.Notably,the mechanism could achieve leveling on slopes with inclination angles of up to 7.5°.Comprehensive evaluations of the liftable chassis system were conducted under both static and dynamic conditions.In the static tests,the system exhibited the capacity for comprehensive or unilateral auto-leveling contingent upon the tilt,with leveling times and angular variations confined to 3.6 s and±0.4°,respectively.In dynamic tests conducted on sloped fields and paddy soils,the system reduced post-leveling mean tilt angles and standard deviations remained below 1.2°and 0.6°,respectively.These results demonstrated a substantial improvement in the stability and reliability of the chassis during operations.This research provides valuable insights into the design and optimization of automatic leveling mechanisms and structural innovations for harvester chassis.展开更多
A solution of 0.1 mol/L to 1.0 mol/L H2SO4 can dissolve alkali metals and alkaline earth metals which weaken an active site of SCR catalyst. The waste catalyst washed with 0.5 mol/L H2SO4 regained the best catalytic a...A solution of 0.1 mol/L to 1.0 mol/L H2SO4 can dissolve alkali metals and alkaline earth metals which weaken an active site of SCR catalyst. The waste catalyst washed with 0.5 mol/L H2SO4 regained the best catalytic activity. When a concentration of the sulfuric acid is less than 0.5 mol/L, sufficient cleaning effects cannot be obtained. In contrast, when the concentration is greater than 1.0 tool/L, the active components, vanadium and tungsten are undesirably eluted. The total BET surface of the catalyst regenerated by air lift loop reactor showed almost the same as that of fresh catalyst due to the removal of insoluble compounds which may be penetrated into pores of catalyst. The addition of a solution of 0.075 mol/L ammonium vanadate （NHnVO3） and 0.075 mol/L ammonium paratungstate （5（NH4）20· 12WO3-5H20） to 0.1 mol/L H2SO4 significantly increases the activity of the waste catalyst.展开更多
In order to investigate the characteristics of particle-induced pressure loss in the solid–liquid lifting pipe,a series of experiments were conducted in 200 mm diameter lifting pipe.Simulation manganese nodules with ...In order to investigate the characteristics of particle-induced pressure loss in the solid–liquid lifting pipe,a series of experiments were conducted in 200 mm diameter lifting pipe.Simulation manganese nodules with five different mean diameters of10 mm,20 mm,30 mm,40 mm and 50 mm were used,both in isolation and a combination in equal fraction by mass.The flow velocities in the lifting pipe ranged from 0.12 m/s to 1.61 m/s,and the mass of particles employed was 10 kg for each particle diameter.Three regimes,wavy bed,partly fluidization,and fully fluidization,were observed over the flow velocity.The solid–liquid pressure drop data were measured by differential pressure transmitter,and pressure drop caused by the solid particles was calculated and analyzed.The results show that the evolutions of the pressure loss due to solid particles are relevant to the solid–liquid flow regimes,and they are distinctly influenced by fluid velocity and particle size.展开更多
The initial motivation of the lifting technique is to solve the H∞control problems. However, the conventional weighted H∞design does not meet the conditions required by lifting, so the result often leads to a misjud...The initial motivation of the lifting technique is to solve the H∞control problems. However, the conventional weighted H∞design does not meet the conditions required by lifting, so the result often leads to a misjudgement of the design. Two conditions required by using the lifting technique are presented based on the basic formulae of the lifting. It is pointed out that only the H∞disturbance attenuation problem with no weighting functions can meet these conditions, hence, the application of the lifting technique is quite limited.展开更多
A nonlinear finite element model of the nut post reinforced concrete （RC） structure of the safety mechanism in the Three Gorges Project （TGP） ship lift was built by ANSYS software. Some irregular structures such a...A nonlinear finite element model of the nut post reinforced concrete （RC） structure of the safety mechanism in the Three Gorges Project （TGP） ship lift was built by ANSYS software. Some irregular structures such as the nut post and the rotary rod were divided by curved surface into a series of regular parts, and the structures were all meshed to hexahedron. Constraint equations were defined between two interfaces with different element sizes and mesh patterns. PRETS179 elements were used to simulate the preload in the tendons and the pre-stressed screws, and the loss of prestressing force was calculated. Five extreme load cases were analyzed. The stress of each part in the structure was obtained. The results indicate that the maximum compressive stress of concrete C35 is 24.13 MPa, so the concrete may be partially crushed; the maximum tensile stress of the grouting motar is 6.73 MPa, so the grouting motar may partially fracture; the maximum yon Mises stress of the rotary rod is 648.70 MPa, therefore the rotary rod may partially yield.展开更多
A novel adaptive fault-tolerant control scheme in the differential algebraic framework was proposed for attitude control of a heavy lift launch vehicle （HLLV）. By using purely mathematical transformations, the decou...A novel adaptive fault-tolerant control scheme in the differential algebraic framework was proposed for attitude control of a heavy lift launch vehicle （HLLV）. By using purely mathematical transformations, the decoupled input-output representations of HLLV were derived, rendering three decoupled second-order systems, i.e., pitch, yaw and roll channels. Based on a new type of numerical differentiator, a differential algebraic observer （DAO） was proposed for estimating the system states and the generalized disturbances, including various disturbances and additive fault torques. Driven by DAOs, three improved proportional-integral- differential （PID） controllers with disturbance compensation were designed for pitch, yaw and roll control. All signals in the closed-loop system were guaranteed to be ultimately uniformly bounded by utilization of Lyapunov＇s indirect method. The convincing numerical simulations indicate that the proposed control scheme is successful in achieving high performance in the presence of parametric perturbations, external disturbances, noisy corruptions, and actuator faults.展开更多
The pinion bracket-assembly(PBA) is a major part of three gorges project(TGP) ship lift drive system. The static strength,fatigue strength and stress distribution of hinge pin of PBA were analyzed by ANSYS, and the st...The pinion bracket-assembly(PBA) is a major part of three gorges project(TGP) ship lift drive system. The static strength,fatigue strength and stress distribution of hinge pin of PBA were analyzed by ANSYS, and the structure of PBA was optimized. The results show that after the optimization, the maximum comprehensive stress is 259.59 MPa, the maximum fatigue cumulative damage of weld joints is 0.94 and the maximum vertical deformation of hinge pin is 0.14 mm. The elastic deformation, hydropneumatic spring cylinder(HSC) load response and the vibration characteristics of PBA were studied by the bearing test when PBA bore the load caused by different water level errors. The results indicate that when the water level of ship chamber ranges from 3.4 m to 3.6 m,the vertical elastic deformation of the pinion shaft is between-8.58 and 10.50 mm. When upward outage-load(1580 k N) is imposed by the test-rack, the vertical elastic deformation of the pinion shaft is 13.42 and 14.07 mm and HSC load response is 795.80-800.80 k N. In the process of imposing load on the pinion by the test-rack, the maximum vibration amplitude and acceleration of PBA internal components are 0.37° and 2.67 rad/s2, respectively; the maximum impact on the pin caused by vibration is 19.89 k N; the pinion shaft vertical displacement and HSC load response do not fluctuate. There is a great difference between the frequency of meshing force of the pinion and the rack(1.06 Hz) and first-order natural frequency of PBA(8.41 Hz), thus PBA will not resonate.From all above, PBA meets the static strength and fatigue strength requirements. The vibration of PBA internal components has no effect on the vertical displacement of the pinion shaft, HSC load response and smooth operation of PBA. There is a liner relationship in the ratio of 2:1 between the thrust imposed by the test-rack and HSC load, thus HSC can limit the load imposed on the pinion.展开更多
This paper presents a modified analytical model to evaluate the trajectories of various lift separation sabot configurations.The aerodynamic forces acting on the sabot surfaces during a supersonic flight are modeled i...This paper presents a modified analytical model to evaluate the trajectories of various lift separation sabot configurations.The aerodynamic forces acting on the sabot surfaces during a supersonic flight are modeled in the present analytical model by incorporating the pressures on the windward side of the sabot due to the detached/attached shock and its reflections and then integrated using the 3-DoF dynamical equations.The trajectory and the aerodynamic coefficients were obtained for these configurations at a projectile Mach number of 3.The sabot configurations,which include two new designs,are compared with each other and with the conventional free flight trajectory data of the conventional sabots.The mechanical interaction between the sabot and projectile is also addressed in the present work.The comparison shows that the new designs with the aerodynamic surfaces close to the center of gravity,lift-off from the projectile with minimal mechanical interaction compared to a conventional sabot.展开更多
基金Sichuan Science and Technology Program(2022YFG0077)。
文摘During the operation of the rice combine harvester,the fuselage tilts due to the tilt and unevenness of the ground affect its maneuverability and operational reliability.Aiming at the problem of leveling due to the tilt of the field surface,this research developed an innovative dual-parallelogram chassis lifting mechanism for rice harvesters designed a hydraulic system to adjust the chassis height by extending the cylinder.Using Adams simulation software,a detailed model of the lifting chassis was constructed to analyze its performance,revealing a direct correlation between the hydraulic cylinder extension and chassis elevation.Notably,the mechanism could achieve leveling on slopes with inclination angles of up to 7.5°.Comprehensive evaluations of the liftable chassis system were conducted under both static and dynamic conditions.In the static tests,the system exhibited the capacity for comprehensive or unilateral auto-leveling contingent upon the tilt,with leveling times and angular variations confined to 3.6 s and±0.4°,respectively.In dynamic tests conducted on sloped fields and paddy soils,the system reduced post-leveling mean tilt angles and standard deviations remained below 1.2°and 0.6°,respectively.These results demonstrated a substantial improvement in the stability and reliability of the chassis during operations.This research provides valuable insights into the design and optimization of automatic leveling mechanisms and structural innovations for harvester chassis.
基金Project(2009T100100602) supported by the Korea Institute of Energy Technology Evaluation and Planning,Korea
文摘A solution of 0.1 mol/L to 1.0 mol/L H2SO4 can dissolve alkali metals and alkaline earth metals which weaken an active site of SCR catalyst. The waste catalyst washed with 0.5 mol/L H2SO4 regained the best catalytic activity. When a concentration of the sulfuric acid is less than 0.5 mol/L, sufficient cleaning effects cannot be obtained. In contrast, when the concentration is greater than 1.0 tool/L, the active components, vanadium and tungsten are undesirably eluted. The total BET surface of the catalyst regenerated by air lift loop reactor showed almost the same as that of fresh catalyst due to the removal of insoluble compounds which may be penetrated into pores of catalyst. The addition of a solution of 0.075 mol/L ammonium vanadate （NHnVO3） and 0.075 mol/L ammonium paratungstate （5（NH4）20· 12WO3-5H20） to 0.1 mol/L H2SO4 significantly increases the activity of the waste catalyst.
文摘在形式化地分析DWT(Discrete Wavelet Transform)Lifting分解的基础上,提出了分解集合的分级结构概念与技术,其克服了求解问题的高复杂性所带来的实际计算与搜索困难;进一步地,从数值稳定性及计算代价两方面研究了分解的评价问题,给出了两种实用的分解稳定性准则;最后,结合分级结构技术提出了最优分解算法.这些方法应用在JPEG2000框架下的图像压缩系统中得到了一些深刻结论,如发现了LTD(Long Then Danger)现象等,可以为压缩系统中小波变换的快速实现提供新的理论依据与实用算法.实验结果表明了上述方法在求解效率与灵活性、寻优速度以及适用范围等方面的优越性.
基金Projects(51174037,51339008)supported by the National Natural Science Foundation of China
文摘In order to investigate the characteristics of particle-induced pressure loss in the solid–liquid lifting pipe,a series of experiments were conducted in 200 mm diameter lifting pipe.Simulation manganese nodules with five different mean diameters of10 mm,20 mm,30 mm,40 mm and 50 mm were used,both in isolation and a combination in equal fraction by mass.The flow velocities in the lifting pipe ranged from 0.12 m/s to 1.61 m/s,and the mass of particles employed was 10 kg for each particle diameter.Three regimes,wavy bed,partly fluidization,and fully fluidization,were observed over the flow velocity.The solid–liquid pressure drop data were measured by differential pressure transmitter,and pressure drop caused by the solid particles was calculated and analyzed.The results show that the evolutions of the pressure loss due to solid particles are relevant to the solid–liquid flow regimes,and they are distinctly influenced by fluid velocity and particle size.
基金Supported by the Harbin Engineering University Fund for Basic Projects (heuft06041)
文摘The initial motivation of the lifting technique is to solve the H∞control problems. However, the conventional weighted H∞design does not meet the conditions required by lifting, so the result often leads to a misjudgement of the design. Two conditions required by using the lifting technique are presented based on the basic formulae of the lifting. It is pointed out that only the H∞disturbance attenuation problem with no weighting functions can meet these conditions, hence, the application of the lifting technique is quite limited.
基金Project (SPKJ 016-06) supported by the Key Research Project of State Power CorporationProject (2004AC101D31) supported the Key Scientific Research Project of Hubei Province, China
文摘A nonlinear finite element model of the nut post reinforced concrete （RC） structure of the safety mechanism in the Three Gorges Project （TGP） ship lift was built by ANSYS software. Some irregular structures such as the nut post and the rotary rod were divided by curved surface into a series of regular parts, and the structures were all meshed to hexahedron. Constraint equations were defined between two interfaces with different element sizes and mesh patterns. PRETS179 elements were used to simulate the preload in the tendons and the pre-stressed screws, and the loss of prestressing force was calculated. Five extreme load cases were analyzed. The stress of each part in the structure was obtained. The results indicate that the maximum compressive stress of concrete C35 is 24.13 MPa, so the concrete may be partially crushed; the maximum tensile stress of the grouting motar is 6.73 MPa, so the grouting motar may partially fracture; the maximum yon Mises stress of the rotary rod is 648.70 MPa, therefore the rotary rod may partially yield.
基金Foundation item： Project（2012M521538） supported by China Postdoctoral Science Foundation Project suppolted by Postdoctoral Science Foundation of Central South University
文摘A novel adaptive fault-tolerant control scheme in the differential algebraic framework was proposed for attitude control of a heavy lift launch vehicle （HLLV）. By using purely mathematical transformations, the decoupled input-output representations of HLLV were derived, rendering three decoupled second-order systems, i.e., pitch, yaw and roll channels. Based on a new type of numerical differentiator, a differential algebraic observer （DAO） was proposed for estimating the system states and the generalized disturbances, including various disturbances and additive fault torques. Driven by DAOs, three improved proportional-integral- differential （PID） controllers with disturbance compensation were designed for pitch, yaw and roll control. All signals in the closed-loop system were guaranteed to be ultimately uniformly bounded by utilization of Lyapunov＇s indirect method. The convincing numerical simulations indicate that the proposed control scheme is successful in achieving high performance in the presence of parametric perturbations, external disturbances, noisy corruptions, and actuator faults.
基金Project(SPKJ016-06)supported by the Key Research Project of State Power Corporation,ChinaProject(2004AC1O1D31)supported by the Key Scientific Research Project of Hubei Province,ChinaProject(0722018)supported by the China Three Gorges Corporation
文摘The pinion bracket-assembly(PBA) is a major part of three gorges project(TGP) ship lift drive system. The static strength,fatigue strength and stress distribution of hinge pin of PBA were analyzed by ANSYS, and the structure of PBA was optimized. The results show that after the optimization, the maximum comprehensive stress is 259.59 MPa, the maximum fatigue cumulative damage of weld joints is 0.94 and the maximum vertical deformation of hinge pin is 0.14 mm. The elastic deformation, hydropneumatic spring cylinder(HSC) load response and the vibration characteristics of PBA were studied by the bearing test when PBA bore the load caused by different water level errors. The results indicate that when the water level of ship chamber ranges from 3.4 m to 3.6 m,the vertical elastic deformation of the pinion shaft is between-8.58 and 10.50 mm. When upward outage-load(1580 k N) is imposed by the test-rack, the vertical elastic deformation of the pinion shaft is 13.42 and 14.07 mm and HSC load response is 795.80-800.80 k N. In the process of imposing load on the pinion by the test-rack, the maximum vibration amplitude and acceleration of PBA internal components are 0.37° and 2.67 rad/s2, respectively; the maximum impact on the pin caused by vibration is 19.89 k N; the pinion shaft vertical displacement and HSC load response do not fluctuate. There is a great difference between the frequency of meshing force of the pinion and the rack(1.06 Hz) and first-order natural frequency of PBA(8.41 Hz), thus PBA will not resonate.From all above, PBA meets the static strength and fatigue strength requirements. The vibration of PBA internal components has no effect on the vertical displacement of the pinion shaft, HSC load response and smooth operation of PBA. There is a liner relationship in the ratio of 2:1 between the thrust imposed by the test-rack and HSC load, thus HSC can limit the load imposed on the pinion.
文摘This paper presents a modified analytical model to evaluate the trajectories of various lift separation sabot configurations.The aerodynamic forces acting on the sabot surfaces during a supersonic flight are modeled in the present analytical model by incorporating the pressures on the windward side of the sabot due to the detached/attached shock and its reflections and then integrated using the 3-DoF dynamical equations.The trajectory and the aerodynamic coefficients were obtained for these configurations at a projectile Mach number of 3.The sabot configurations,which include two new designs,are compared with each other and with the conventional free flight trajectory data of the conventional sabots.The mechanical interaction between the sabot and projectile is also addressed in the present work.The comparison shows that the new designs with the aerodynamic surfaces close to the center of gravity,lift-off from the projectile with minimal mechanical interaction compared to a conventional sabot.
