This paper presents the automatic guidance system of an agricultural tractor and the side shift control of the attached row crop cultivator using electro-hydraulic actuators. In order to simulate the dynamic behaviour...This paper presents the automatic guidance system of an agricultural tractor and the side shift control of the attached row crop cultivator using electro-hydraulic actuators. In order to simulate the dynamic behaviour of the tractor along with the attached cultivator, the modified bicycle model was adopted. Steering angle sensor, fibre optic gyroscope （FOG） and RTK-DGPS technologies are assumed for measurements of the steering angle, yaw rate and the lateral position of the tractor, respectively. The kinematics model was used for the implement. In this study four cascade controllers were designed and simulated for tractor guidance which consists ofPD, PD, P and PID controllers. Other PI and PID controllers also had been designed for implement side shifting purpose. Then, these two systems were combined and the performance of the whole system was evaluated through the simulation results. According to the results tractor reaches the desired path after less than 10 seconds. Simulations showed that the maximum deviation of the tractor from the desired path was about 5 cm within this period. And the cultivator blades would follow the predetermined path with steady state error of about 5 cm too.展开更多
Using hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle as a simulation example, the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle were simulated and disc...Using hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle as a simulation example, the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle were simulated and discussed with SIMULINK software and hydraulic control theory. The results show that the dynamic characteristics of hydraulic power steering system are improved obviously by using bladder accumulator, the hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle generates vibration at the initial stage under the normal steering condition of pulse input, and its static response time is 0.25 s shorter than that without bladder accumulator. Under the normal steering working condition, the capacity of steering accumulator for absorbing pulse is directly proportional to the cross section area of connecting pipeline, and inversely proportional to the length of connecting pipeline. At the same time, the precharge pressure of nitrogen in steering accumulator should be 60%80% of the rated minimum working pressure of hydraulic power steering system. Under the abnormal steering working condition, the steering cylinder piston may obtain higher motion velocity, and the dynamic response velocity of hydraulic power steering system can be increased by reducing the pressure drop of hydraulic pipelines between the accumulator and steering cylinder and by increasing the rated pressure of hydraulic power steering system, but the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle have nothing to do with the precharge pressure of nitrogen in steering accumulator.展开更多
A new control law is proposed to asymptotically stabilize the chaotic neuron system based on LaSalleinvariant principle.The control technique does not require analytical knowledge of the system dynamics and operateswi...A new control law is proposed to asymptotically stabilize the chaotic neuron system based on LaSalleinvariant principle.The control technique does not require analytical knowledge of the system dynamics and operateswithout an explicit knowledge of the desired steady-state position.The well-known modified Hodgkin-Huxley (MHH)and Hindmarsh-Rose (HR) model neurons are taken as examples to verify the implementation of our method.Simulationresults show the proposed control law is effective.The outcome of this study is significant since it is helpful to understandthe learning process of a human brain towards the information processing,memory and abnormal discharge of the brainneurons.展开更多
The CPB （Colorado potato beetle）, Leptinotarsa decemlineata （Say）, is the major insect pest of potato crops in North America, Europe and Asia. Large amounts of chemical insecticides are used to control this insect...The CPB （Colorado potato beetle）, Leptinotarsa decemlineata （Say）, is the major insect pest of potato crops in North America, Europe and Asia. Large amounts of chemical insecticides are used to control this insect pest. Also, the CPB has developed over the years a resistance to most of the registered chemical insecticides, including those that were effective at one time. One of the most promising alternatives to chemical insecticides consists of taking advantage of natural enemies. The use of the stinkbug predator Perillus bioculatus to control the CPB has been successful at small scale. However, this natural enemy is not abundant in the nature and its hand release at large scale is not realistic. To remedy to this problem, predators must be massively released in potato fields using a mechanical distributor. Such a machine has been successfully designed and built at the Department of Soils and Agri-Food Engineering of University Lavak In this distributor, masses of predators are placed in small containers and mixed with a carrier material. In the field, the containers are mechanically opened at different locations, based on a source-point mass release option. These locations are determined in advance following a field monitoring of the populations of CPBs. Field trials proved that the mechanical distributor is reliable and ease of use. Its efficiency in releasing insect predators is high and comparable to that obtained in previous laboratory tests.展开更多
An aircraft tractor plays a significant role as a kind of important marine transport and support equipment. It＇s necessary to study its controlling and manoeuvring stability to improve operation efficiency. A virtual...An aircraft tractor plays a significant role as a kind of important marine transport and support equipment. It＇s necessary to study its controlling and manoeuvring stability to improve operation efficiency. A virtual prototyping model of the tractor-aircraft system based on Lagrange＇s equation of the first kind with Lagrange mutipliers was established in this paper, According to the towing characteristics, a path-tracking controller using fuzzy logic theory was designed. Direction control herein was carried out through a compensatory tracking approach. Interactive co-simulation was performed to validate the path-tracking behavior in closed-loop, Simulation results indicated that the tractor followed the reference courses precisely on a flat ground.展开更多
Field experiments were conducted using Ceranock bait station, ＂attract and kill＂ system to combat Mediterranean fruit fly, Ceratitis capitata, in citrus orchards of Baghdad and Wasit governorates, Iraq, during 2013-...Field experiments were conducted using Ceranock bait station, ＂attract and kill＂ system to combat Mediterranean fruit fly, Ceratitis capitata, in citrus orchards of Baghdad and Wasit governorates, Iraq, during 2013-2014 season. Control program was implemented in six citrus orchards of mixed citrus varieties： Orange, Citrus sinensis; Mandarin, C. reticulate; Lemon, C. lemon; and Bergamot, C. aurantium. Ceranock traps 240/ha were hanged in trees of two separate orchards in each location, with third orchard served as control. Delta and McPhail traps supplied with pheromone were used to monitor Medfly population density in treated and control orchards. Results indicated that Medfly activity and presence in citrus orchards started during the first week of October coincide with the beginning of fruits ripening. The result indicated that Medfly population density in Wasit orchards was more than that of Baghdad orchards. The total trapped insects after two weeks of Ceranock were 59, 94, 142 and 205, 277, 765 adults for the firsst, second and the control orchards in the two locations, respectively. The percentage of fruit injuries were increased dramatically when fruits mature and its color turn to yellowish reaching of 35%, 56%, 21% and 32% in mandarin and orange fruits in Baghdad and Wasit orchards, respectively, compared with 3%, 4%, 4% and 5% in treated orchards, respectively. Calculated percentage of fruit damage indicated that reduction in injuries were 97% in mandarin and 96% in orange at Baghdad orchards and were 95% and 96%, respectively, in Wasit orchards. The results of this study demonstrate clearly the efficacy of Ceranock bait station, ＂attract and kill＂ system as a control measure for Medfly in citrus orchards.展开更多
This paper studies denumerable continuous-time Markov decision processes with expected total reward criteria. The authors first study the unconstrained model with possible unbounded transition rates, and give suitable...This paper studies denumerable continuous-time Markov decision processes with expected total reward criteria. The authors first study the unconstrained model with possible unbounded transition rates, and give suitable conditions on the controlled system＇s primitive data under which the authors show the existence of a solution to the total reward optimality equation and also the existence of an optimal stationary policy. Then, the authors impose a constraint on an expected total cost, and consider the associated constrained model. Basing on the results about the unconstrained model and using the Lagrange multipliers approach, the authors prove the existence of constrained-optimal policies under some additional conditions. Finally, the authors apply the results to controlled queueing systems.展开更多
文摘This paper presents the automatic guidance system of an agricultural tractor and the side shift control of the attached row crop cultivator using electro-hydraulic actuators. In order to simulate the dynamic behaviour of the tractor along with the attached cultivator, the modified bicycle model was adopted. Steering angle sensor, fibre optic gyroscope （FOG） and RTK-DGPS technologies are assumed for measurements of the steering angle, yaw rate and the lateral position of the tractor, respectively. The kinematics model was used for the implement. In this study four cascade controllers were designed and simulated for tractor guidance which consists ofPD, PD, P and PID controllers. Other PI and PID controllers also had been designed for implement side shifting purpose. Then, these two systems were combined and the performance of the whole system was evaluated through the simulation results. According to the results tractor reaches the desired path after less than 10 seconds. Simulations showed that the maximum deviation of the tractor from the desired path was about 5 cm within this period. And the cultivator blades would follow the predetermined path with steady state error of about 5 cm too.
文摘Using hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle as a simulation example, the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle were simulated and discussed with SIMULINK software and hydraulic control theory. The results show that the dynamic characteristics of hydraulic power steering system are improved obviously by using bladder accumulator, the hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle generates vibration at the initial stage under the normal steering condition of pulse input, and its static response time is 0.25 s shorter than that without bladder accumulator. Under the normal steering working condition, the capacity of steering accumulator for absorbing pulse is directly proportional to the cross section area of connecting pipeline, and inversely proportional to the length of connecting pipeline. At the same time, the precharge pressure of nitrogen in steering accumulator should be 60%80% of the rated minimum working pressure of hydraulic power steering system. Under the abnormal steering working condition, the steering cylinder piston may obtain higher motion velocity, and the dynamic response velocity of hydraulic power steering system can be increased by reducing the pressure drop of hydraulic pipelines between the accumulator and steering cylinder and by increasing the rated pressure of hydraulic power steering system, but the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle have nothing to do with the precharge pressure of nitrogen in steering accumulator.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10862001 and 10947011the Construction of Key Laboratories in Universities of Guangxi under Grant No. 200912
文摘A new control law is proposed to asymptotically stabilize the chaotic neuron system based on LaSalleinvariant principle.The control technique does not require analytical knowledge of the system dynamics and operateswithout an explicit knowledge of the desired steady-state position.The well-known modified Hodgkin-Huxley (MHH)and Hindmarsh-Rose (HR) model neurons are taken as examples to verify the implementation of our method.Simulationresults show the proposed control law is effective.The outcome of this study is significant since it is helpful to understandthe learning process of a human brain towards the information processing,memory and abnormal discharge of the brainneurons.
文摘The CPB （Colorado potato beetle）, Leptinotarsa decemlineata （Say）, is the major insect pest of potato crops in North America, Europe and Asia. Large amounts of chemical insecticides are used to control this insect pest. Also, the CPB has developed over the years a resistance to most of the registered chemical insecticides, including those that were effective at one time. One of the most promising alternatives to chemical insecticides consists of taking advantage of natural enemies. The use of the stinkbug predator Perillus bioculatus to control the CPB has been successful at small scale. However, this natural enemy is not abundant in the nature and its hand release at large scale is not realistic. To remedy to this problem, predators must be massively released in potato fields using a mechanical distributor. Such a machine has been successfully designed and built at the Department of Soils and Agri-Food Engineering of University Lavak In this distributor, masses of predators are placed in small containers and mixed with a carrier material. In the field, the containers are mechanically opened at different locations, based on a source-point mass release option. These locations are determined in advance following a field monitoring of the populations of CPBs. Field trials proved that the mechanical distributor is reliable and ease of use. Its efficiency in releasing insect predators is high and comparable to that obtained in previous laboratory tests.
基金Harbin Technological Innovation Research Fund(NO:2012RFXXG039)
文摘An aircraft tractor plays a significant role as a kind of important marine transport and support equipment. It＇s necessary to study its controlling and manoeuvring stability to improve operation efficiency. A virtual prototyping model of the tractor-aircraft system based on Lagrange＇s equation of the first kind with Lagrange mutipliers was established in this paper, According to the towing characteristics, a path-tracking controller using fuzzy logic theory was designed. Direction control herein was carried out through a compensatory tracking approach. Interactive co-simulation was performed to validate the path-tracking behavior in closed-loop, Simulation results indicated that the tractor followed the reference courses precisely on a flat ground.
文摘Field experiments were conducted using Ceranock bait station, ＂attract and kill＂ system to combat Mediterranean fruit fly, Ceratitis capitata, in citrus orchards of Baghdad and Wasit governorates, Iraq, during 2013-2014 season. Control program was implemented in six citrus orchards of mixed citrus varieties： Orange, Citrus sinensis; Mandarin, C. reticulate; Lemon, C. lemon; and Bergamot, C. aurantium. Ceranock traps 240/ha were hanged in trees of two separate orchards in each location, with third orchard served as control. Delta and McPhail traps supplied with pheromone were used to monitor Medfly population density in treated and control orchards. Results indicated that Medfly activity and presence in citrus orchards started during the first week of October coincide with the beginning of fruits ripening. The result indicated that Medfly population density in Wasit orchards was more than that of Baghdad orchards. The total trapped insects after two weeks of Ceranock were 59, 94, 142 and 205, 277, 765 adults for the firsst, second and the control orchards in the two locations, respectively. The percentage of fruit injuries were increased dramatically when fruits mature and its color turn to yellowish reaching of 35%, 56%, 21% and 32% in mandarin and orange fruits in Baghdad and Wasit orchards, respectively, compared with 3%, 4%, 4% and 5% in treated orchards, respectively. Calculated percentage of fruit damage indicated that reduction in injuries were 97% in mandarin and 96% in orange at Baghdad orchards and were 95% and 96%, respectively, in Wasit orchards. The results of this study demonstrate clearly the efficacy of Ceranock bait station, ＂attract and kill＂ system as a control measure for Medfly in citrus orchards.
基金supported by the National Natural Science Foundation of China under Grant Nos.10925107 and 60874004
文摘This paper studies denumerable continuous-time Markov decision processes with expected total reward criteria. The authors first study the unconstrained model with possible unbounded transition rates, and give suitable conditions on the controlled system＇s primitive data under which the authors show the existence of a solution to the total reward optimality equation and also the existence of an optimal stationary policy. Then, the authors impose a constraint on an expected total cost, and consider the associated constrained model. Basing on the results about the unconstrained model and using the Lagrange multipliers approach, the authors prove the existence of constrained-optimal policies under some additional conditions. Finally, the authors apply the results to controlled queueing systems.
