The principle of increasing structural loading abillity by the using of elastic-plastic con- trolling design, which can make steel reach a highcr yield slrength through controlling undue strains produced in loaded box...The principle of increasing structural loading abillity by the using of elastic-plastic con- trolling design, which can make steel reach a highcr yield slrength through controlling undue strains produced in loaded box steel structures and no damager to the static mechanical properties of the used materials, is dealt with under the guarantee of strength, rigidity, and stability. A new idea of elastic--plastic controlling design, which is mainly based on the elastic-plastic theory and experi- mental results and is different from the current design which is mainly based handbooks and design- er' s experience, is established. That is: the loading time and its effect on loaded structures are con- sidered, and the potential strength in used matcrials is fully utilized through the controlling of struc- tural strains in design. By the using of this design method, the weight and cost of box structures will be reduced in large amount.展开更多
Optimal weights are usually obtained in neural network through a fixed network conformation,which affects the practicality of the network.Aiming at the shortage of conformation design and weight training algorithm in ...Optimal weights are usually obtained in neural network through a fixed network conformation,which affects the practicality of the network.Aiming at the shortage of conformation design and weight training algorithm in neural network application,the back propagation(BP)neural network learning algorithm combined with simulated annealing genetic algorithm(SAGA)is put forward.The multi-point genetic optimization of neural network topology and network weights is performed using hierarchical coding schemes and genetic operations.The simulated annealing mechanism is incorporated into the Genetic Algorithm(GA)to optimize the design and optimization of neural network conformation and network weights simultaneously.The SAGA takes advantage of GA excellent ability in grasping the overall ability of the search process,also uses the SA algorithm to control the convergence of the algorithm to avoid premature phenomenon.The fault diagnosis of one certain on-board electrical control box of helicopter and one certain flight control box of aircraft autopilot were used as a test platform to simulate the algorithm.The simulation conclusions reveal that the algorithm has good convergence rate and high diagnostic accurateness.展开更多
A newcontrolled seed metering unit was designed and mounted on a common grain drill for direct seeding of wheat(DSW).It comprised the following main parts:(a)a variable-rate controlled direct current motor(DCM)as seed...A newcontrolled seed metering unit was designed and mounted on a common grain drill for direct seeding of wheat(DSW).It comprised the following main parts:(a)a variable-rate controlled direct current motor(DCM)as seed metering shaft driver,(b)two digital encoders for sensing the rotational speed of supplemental ground wheel(SGW)and seed metering shaft and(c)a control box to handle and process the data of the unit.According to the considered closed-loop control system,the designed control box regularly checked the revolution per minute(RPM)of seed metering shaft,as operation feedback,using its digital encoder output.The seeding ratewas determined based on the calculated error signal and output signal of the digital encoder of the SGW.A field with four different levels of wheat stubble coverage(10%,30%,40%and 50%)was selected for evaluation of the fabricated seed metering unit(FSMU).The dynamic tests were conducted to compare the performance of installed FSMU on the grain drill and equipped grain drill with common seed metering unit(CSMU)at three forward speeds of 4,6 and 8(Km/h)for DSW.Results of the FSMU assessment demonstrated that an increase in forwardspeed of grain drill(FSGD)and stubble coverage did not significantly affect the seeding rate in the grain drill forDSW.Using theFSMU reduced the coefficient of variation(CV)by approximately 50%.Consequently,applying the FSMU on the common grain drill led to a desirable seeding rate at different forward speeds of the grain drill and stubble existence.展开更多
文摘The principle of increasing structural loading abillity by the using of elastic-plastic con- trolling design, which can make steel reach a highcr yield slrength through controlling undue strains produced in loaded box steel structures and no damager to the static mechanical properties of the used materials, is dealt with under the guarantee of strength, rigidity, and stability. A new idea of elastic--plastic controlling design, which is mainly based on the elastic-plastic theory and experi- mental results and is different from the current design which is mainly based handbooks and design- er' s experience, is established. That is: the loading time and its effect on loaded structures are con- sidered, and the potential strength in used matcrials is fully utilized through the controlling of struc- tural strains in design. By the using of this design method, the weight and cost of box structures will be reduced in large amount.
文摘Optimal weights are usually obtained in neural network through a fixed network conformation,which affects the practicality of the network.Aiming at the shortage of conformation design and weight training algorithm in neural network application,the back propagation(BP)neural network learning algorithm combined with simulated annealing genetic algorithm(SAGA)is put forward.The multi-point genetic optimization of neural network topology and network weights is performed using hierarchical coding schemes and genetic operations.The simulated annealing mechanism is incorporated into the Genetic Algorithm(GA)to optimize the design and optimization of neural network conformation and network weights simultaneously.The SAGA takes advantage of GA excellent ability in grasping the overall ability of the search process,also uses the SA algorithm to control the convergence of the algorithm to avoid premature phenomenon.The fault diagnosis of one certain on-board electrical control box of helicopter and one certain flight control box of aircraft autopilot were used as a test platform to simulate the algorithm.The simulation conclusions reveal that the algorithm has good convergence rate and high diagnostic accurateness.
文摘A newcontrolled seed metering unit was designed and mounted on a common grain drill for direct seeding of wheat(DSW).It comprised the following main parts:(a)a variable-rate controlled direct current motor(DCM)as seed metering shaft driver,(b)two digital encoders for sensing the rotational speed of supplemental ground wheel(SGW)and seed metering shaft and(c)a control box to handle and process the data of the unit.According to the considered closed-loop control system,the designed control box regularly checked the revolution per minute(RPM)of seed metering shaft,as operation feedback,using its digital encoder output.The seeding ratewas determined based on the calculated error signal and output signal of the digital encoder of the SGW.A field with four different levels of wheat stubble coverage(10%,30%,40%and 50%)was selected for evaluation of the fabricated seed metering unit(FSMU).The dynamic tests were conducted to compare the performance of installed FSMU on the grain drill and equipped grain drill with common seed metering unit(CSMU)at three forward speeds of 4,6 and 8(Km/h)for DSW.Results of the FSMU assessment demonstrated that an increase in forwardspeed of grain drill(FSGD)and stubble coverage did not significantly affect the seeding rate in the grain drill forDSW.Using theFSMU reduced the coefficient of variation(CV)by approximately 50%.Consequently,applying the FSMU on the common grain drill led to a desirable seeding rate at different forward speeds of the grain drill and stubble existence.
