The mechanism of a hydro-viscous soft start is of great importance in the design of a hydro-viscous clutch and its control system. To explain the mechanism of a hydro-viscous soft start, the startup process of a belt ...The mechanism of a hydro-viscous soft start is of great importance in the design of a hydro-viscous clutch and its control system. To explain the mechanism of a hydro-viscous soft start, the startup process of a belt conveyor was numerically analyzed with the modified Reynolds equation, an energy equation and a temperature-viscosity equation. The effect of temperature and grooves of the friction disk surface on torque transfer and load capacity of the oil film have also been analyzed. The results show that 1) the grooves are the basis of forming dynamic pressure but they may reduce the capacity of torque transfer to a certain extent, 2) during the startup process, temperature has little effect on torque transfer and load capacity and the variation in load capacity of the oil film is very small, indicating that it is preferable to use the flow rate as a control object than the pressure of the feed cylinder. The results have been verified by an experiment.展开更多
Based on the concept of ecosystem carrying capacity,the indicator system of quantitative assessment was set up,which consisted of support indicator system and pressure indicator system.And the factor analysis method w...Based on the concept of ecosystem carrying capacity,the indicator system of quantitative assessment was set up,which consisted of support indicator system and pressure indicator system.And the factor analysis method was used to screen the indicator system.Different from the traditional indicator weight determination based on the absolute values of the coefficients of regression equation,the squares of factor loadings in the rotated component matrix were attempted to determine the weights of 40 assessment indicators.The result shows that ecological support system and pressure system in Binhai New Area are relatively balanced among six years,and the developing level of urban ecosystem is basically healthy on the whole.However,due to continuously increasing pressure of the resources consumption caused by the rapid growth of the second industry,which is the Leading Industry of Binhai New Area,the ecosystem carrying capacity reached the minimum in 2005.展开更多
The study analyzes the characteristics of roof movement in mining top coal of inclined coal seam,and establishes the mechanical model of support and surrounding-rock stability in inclined coal seam.Besides,this study ...The study analyzes the characteristics of roof movement in mining top coal of inclined coal seam,and establishes the mechanical model of support and surrounding-rock stability in inclined coal seam.Besides,this study carries out the numerical calculation and field observation of roof movement and support stability,and provides the critical control measures.The results show that the fracture firstly appears in middle-upper roof and extends upwards in top coal caving in inclined coal seam;regular and irregular caving zones appear in middle-upper stress concentration region,and the asymmetric caving arch is finally formed.Support load of middle-upper working face is larger than that of the middle-lower face;dynamic load coefficient of upper support is large,and the load on the front of support is larger than that on the rear of it,which leads to poor support stability.Stability of support and surrounding-rock system depends mainly on upper-support stability.展开更多
Ship-mounted container cranes are challenging industrial applications of nonlinear pendulum-like systems with oscillating disturbance which can cause them unstable.Since wave-induced ship motion causes the hoisted con...Ship-mounted container cranes are challenging industrial applications of nonlinear pendulum-like systems with oscillating disturbance which can cause them unstable.Since wave-induced ship motion causes the hoisted container to swing during the transfer operation,the swing motion may be dangerously large and the operation must be stopped.In order to reduce payload pendulation of ship-mounted crane,nonlinear dynamics of ship-mounted crane is derived and a control method using T-S fuzzy model is proposed.Simulation results are given to illustrate the validity of the proposed design method and pendulation of ship-mounted crane is reduced significantly.展开更多
GIS （geographic information systems） is often used for planning purposes in forestry. This is mainly used to give directives for the operators to cut the trees. And nowadays, it is also used for marking of areas wit...GIS （geographic information systems） is often used for planning purposes in forestry. This is mainly used to give directives for the operators to cut the trees. And nowadays, it is also used for marking of areas with high environmental values where considerations should be made. The minor used techniques is to incorporate soil information maps as an overlay to give information to forest machine operators where less good trafficability is to be expected, especially after a heavy rain. By marking areas with bad bearing capacity, the operators may save both time and money, and do not bog down with the machine. When the soils bearing capacity is less than 0.7 MPa and the ground pressure of the machine is more than 80 kPa, either smaller machines must be used or bogey tracks should be used to decrease the risk for getting stuck or causing severe rutting. By choosing good types of bogey tracks both rutting and fuel consumption will be decreased for the health of forest land and the contractor.展开更多
Measuring the top coal movement and abutment pressure about Teaching ThirdMine that belonged to the National Energy Investment and Development.It shows that thetop coal's strong compression occurs 6 m in front of ...Measuring the top coal movement and abutment pressure about Teaching ThirdMine that belonged to the National Energy Investment and Development.It shows that thetop coal's strong compression occurs 6 m in front of the face, the top coal is in front of sideabutment pressure concentration increase area at this time, and the top coal horizontaldisplacement increase rapidly.Also analyzed the top coal mechanical properties, and thetop coal under abutment pressure turned into block state.Finally, analyzed the top coalfailure mechanism and the structure of the mechanical model, and also made a theoreticalanalysis of the top coal's ultimate bearing capacity.展开更多
New program was proposed in LM-6 rolling control technology that using high-pressure staged combustion gas. Launch vehicle rolling control by just one engine was realized. Under the limit of the rolling control moment...New program was proposed in LM-6 rolling control technology that using high-pressure staged combustion gas. Launch vehicle rolling control by just one engine was realized. Under the limit of the rolling control moment of the launch vehicle, a new attitude dynamic model is established. Interference source and how to reduce the effect was analyzed, and method of designing a pre-compensated robust controller was proposed. Simulation and flight resuits showed that the attitude dynamic model established and the pre-compensation robust controller proposed in this paper could solve the key problems with a strong coupling attitude controller, and realize high quality and high reliability control in wind areas, and improve the capability of the launch vehicle.展开更多
The technological development status of new generation low cost small-lift launch vehicles applied to small satellite launch is investigated in this paper. The development trends are summarized, including low cost and...The technological development status of new generation low cost small-lift launch vehicles applied to small satellite launch is investigated in this paper. The development trends are summarized, including low cost and rapid response capability, utilization of mature rocket and missile technology, the development of mobile launch technology adopting air-based platforms and use of innovative technology. Moreover, the external power and internal demand of the small-lift launch vehicle are analyzed and the market prospect is forecasted. Finally, proposals for the development of small-lift launch vehicles are put forward, including exploration of the potential of existing rocket and missile technology, development of multi-platform mobile launch technology and further application of innovative technology and ideas.展开更多
A screw drive in-pipe robot is promising inspection equipment for small pipes. However, most of the existing screw drive in-pipe robots have problems of motion interference and slipping inside curved or irregular pipe...A screw drive in-pipe robot is promising inspection equipment for small pipes. However, most of the existing screw drive in-pipe robots have problems of motion interference and slipping inside curved or irregular pipes. These problems result from the coupled relations among the steering motion, the motion speed and the load ability of the robot. In order to deal with the problems, the axiomatic design （AD） theory is applied to evaluate and analyze the existing designs. Then an uncoupled con- cept design based on the AD theory is proposed and the complete AD decomposition process is presented. After that, the pro- posed robot based on a tri-axial differential angle modulation mechanism is designed to realize the uncoupled concept. Finally, the uncoupled property is verified in a dynamics simulation system. The simulation results indicate that the mc tion speed, load ability and steering motion of the proposed robot can be adjusted individually compared with the robots taat have inclin- ing-angle-fixed rollers. Owing to the uncoupled design, the proposed robot can mechanically adapt to straight pipes and curved pipes with less roller slipping.展开更多
Dynamic modeling and active control of a strap-on launch vehicle are studied in this paper. In the dynamic modeling, the double-compatible free-interface modal synthesis method is used to establish dynamic model of th...Dynamic modeling and active control of a strap-on launch vehicle are studied in this paper. In the dynamic modeling, the double-compatible free-interface modal synthesis method is used to establish dynamic model of the system, and its model precision is compared with those of finite element method(FEM), fixedinterface modal synthesis method and free-interface modal synthesis method. In the active control, the swing angle of rocket motor is used as design variable, and the control law design based on the model of mass center motion is adopted to validate the system. Simulation results indicate that the double-compatible model synthesis method can properly approximate the FEM which is used as the benchmark solution, and the model precision of the double-compatible modal synthesis method is obviously higher than those of the fixed-interface and freeinterface modal synthesis methods. Based on the control law design, the deflection of mass center of the launch vehicle is very small.展开更多
文摘The mechanism of a hydro-viscous soft start is of great importance in the design of a hydro-viscous clutch and its control system. To explain the mechanism of a hydro-viscous soft start, the startup process of a belt conveyor was numerically analyzed with the modified Reynolds equation, an energy equation and a temperature-viscosity equation. The effect of temperature and grooves of the friction disk surface on torque transfer and load capacity of the oil film have also been analyzed. The results show that 1) the grooves are the basis of forming dynamic pressure but they may reduce the capacity of torque transfer to a certain extent, 2) during the startup process, temperature has little effect on torque transfer and load capacity and the variation in load capacity of the oil film is very small, indicating that it is preferable to use the flow rate as a control object than the pressure of the feed cylinder. The results have been verified by an experiment.
文摘Based on the concept of ecosystem carrying capacity,the indicator system of quantitative assessment was set up,which consisted of support indicator system and pressure indicator system.And the factor analysis method was used to screen the indicator system.Different from the traditional indicator weight determination based on the absolute values of the coefficients of regression equation,the squares of factor loadings in the rotated component matrix were attempted to determine the weights of 40 assessment indicators.The result shows that ecological support system and pressure system in Binhai New Area are relatively balanced among six years,and the developing level of urban ecosystem is basically healthy on the whole.However,due to continuously increasing pressure of the resources consumption caused by the rapid growth of the second industry,which is the Leading Industry of Binhai New Area,the ecosystem carrying capacity reached the minimum in 2005.
基金the financial support received from the National Natural Science Foundation of China (No.51174078)Ph.D.Foundation of Henan Polytechnic University (No.60207004) of Chinathe Fostering Foundation of Henan Polytechnic University for the Excellent Ph.D.Dissertation of China (No.508063)
文摘The study analyzes the characteristics of roof movement in mining top coal of inclined coal seam,and establishes the mechanical model of support and surrounding-rock stability in inclined coal seam.Besides,this study carries out the numerical calculation and field observation of roof movement and support stability,and provides the critical control measures.The results show that the fracture firstly appears in middle-upper roof and extends upwards in top coal caving in inclined coal seam;regular and irregular caving zones appear in middle-upper stress concentration region,and the asymmetric caving arch is finally formed.Support load of middle-upper working face is larger than that of the middle-lower face;dynamic load coefficient of upper support is large,and the load on the front of support is larger than that on the rear of it,which leads to poor support stability.Stability of support and surrounding-rock system depends mainly on upper-support stability.
基金work supported by Changwon National University in 2011-2012work partly supported by the second stage of Brain Korea 21 Projects
文摘Ship-mounted container cranes are challenging industrial applications of nonlinear pendulum-like systems with oscillating disturbance which can cause them unstable.Since wave-induced ship motion causes the hoisted container to swing during the transfer operation,the swing motion may be dangerously large and the operation must be stopped.In order to reduce payload pendulation of ship-mounted crane,nonlinear dynamics of ship-mounted crane is derived and a control method using T-S fuzzy model is proposed.Simulation results are given to illustrate the validity of the proposed design method and pendulation of ship-mounted crane is reduced significantly.
文摘GIS （geographic information systems） is often used for planning purposes in forestry. This is mainly used to give directives for the operators to cut the trees. And nowadays, it is also used for marking of areas with high environmental values where considerations should be made. The minor used techniques is to incorporate soil information maps as an overlay to give information to forest machine operators where less good trafficability is to be expected, especially after a heavy rain. By marking areas with bad bearing capacity, the operators may save both time and money, and do not bog down with the machine. When the soils bearing capacity is less than 0.7 MPa and the ground pressure of the machine is more than 80 kPa, either smaller machines must be used or bogey tracks should be used to decrease the risk for getting stuck or causing severe rutting. By choosing good types of bogey tracks both rutting and fuel consumption will be decreased for the health of forest land and the contractor.
文摘Measuring the top coal movement and abutment pressure about Teaching ThirdMine that belonged to the National Energy Investment and Development.It shows that thetop coal's strong compression occurs 6 m in front of the face, the top coal is in front of sideabutment pressure concentration increase area at this time, and the top coal horizontaldisplacement increase rapidly.Also analyzed the top coal mechanical properties, and thetop coal under abutment pressure turned into block state.Finally, analyzed the top coalfailure mechanism and the structure of the mechanical model, and also made a theoreticalanalysis of the top coal's ultimate bearing capacity.
文摘New program was proposed in LM-6 rolling control technology that using high-pressure staged combustion gas. Launch vehicle rolling control by just one engine was realized. Under the limit of the rolling control moment of the launch vehicle, a new attitude dynamic model is established. Interference source and how to reduce the effect was analyzed, and method of designing a pre-compensated robust controller was proposed. Simulation and flight resuits showed that the attitude dynamic model established and the pre-compensation robust controller proposed in this paper could solve the key problems with a strong coupling attitude controller, and realize high quality and high reliability control in wind areas, and improve the capability of the launch vehicle.
文摘The technological development status of new generation low cost small-lift launch vehicles applied to small satellite launch is investigated in this paper. The development trends are summarized, including low cost and rapid response capability, utilization of mature rocket and missile technology, the development of mobile launch technology adopting air-based platforms and use of innovative technology. Moreover, the external power and internal demand of the small-lift launch vehicle are analyzed and the market prospect is forecasted. Finally, proposals for the development of small-lift launch vehicles are put forward, including exploration of the potential of existing rocket and missile technology, development of multi-platform mobile launch technology and further application of innovative technology and ideas.
基金supported by the National Natural Science Foundation of China(Grant No.61273345)
文摘A screw drive in-pipe robot is promising inspection equipment for small pipes. However, most of the existing screw drive in-pipe robots have problems of motion interference and slipping inside curved or irregular pipes. These problems result from the coupled relations among the steering motion, the motion speed and the load ability of the robot. In order to deal with the problems, the axiomatic design （AD） theory is applied to evaluate and analyze the existing designs. Then an uncoupled con- cept design based on the AD theory is proposed and the complete AD decomposition process is presented. After that, the pro- posed robot based on a tri-axial differential angle modulation mechanism is designed to realize the uncoupled concept. Finally, the uncoupled property is verified in a dynamics simulation system. The simulation results indicate that the mc tion speed, load ability and steering motion of the proposed robot can be adjusted individually compared with the robots taat have inclin- ing-angle-fixed rollers. Owing to the uncoupled design, the proposed robot can mechanically adapt to straight pipes and curved pipes with less roller slipping.
基金the National Natural Science Foundation of China(Nos.11132001,11272202 and 11472171)the Key Scientific Project of Shanghai Municipal Education Commission(No.14ZZ021)the Natural Science Foundation of Shanghai(No.14ZR1421000)
文摘Dynamic modeling and active control of a strap-on launch vehicle are studied in this paper. In the dynamic modeling, the double-compatible free-interface modal synthesis method is used to establish dynamic model of the system, and its model precision is compared with those of finite element method(FEM), fixedinterface modal synthesis method and free-interface modal synthesis method. In the active control, the swing angle of rocket motor is used as design variable, and the control law design based on the model of mass center motion is adopted to validate the system. Simulation results indicate that the double-compatible model synthesis method can properly approximate the FEM which is used as the benchmark solution, and the model precision of the double-compatible modal synthesis method is obviously higher than those of the fixed-interface and freeinterface modal synthesis methods. Based on the control law design, the deflection of mass center of the launch vehicle is very small.
