In order to increase the robust performance of electro-hydraulic servo system, the system transfer function was identified by the intergration algorithm of genetic algorithm and ant colony optimization(GA-ACO), which ...In order to increase the robust performance of electro-hydraulic servo system, the system transfer function was identified by the intergration algorithm of genetic algorithm and ant colony optimization(GA-ACO), which was based on standard genetic algorithm and combined with positive feedback mechanism of ant colony algorithm. This method can obtain the precise mathematic model of continuous rotary motor which determines the order of servo system. Firstly, by constructing an appropriate fitness function, the problem of system parameters identification is converted into the problem of system parameter optimization. Secondly, in the given upper and lower bounds a set of optimal parameters are selected to meet the best approximation of the actual system. And the result shows that the identification output can trace the sampling output of actual system, and the error is very small. In addition, another set of experimental data are used to test the identification result. The result shows that the identification parameters can approach the actual system. The experimental results verify the feasibility of this method. And it is fit for the parameter identification of general complex system using the integration algorithm of GA-ACO.展开更多
Through research on the application of hydroviscous speed-adjusting clutch in belt conveyor, this paper concluded that hydroviscous speed-adjusting clutch has many advantages such as controllable start and stop, overl...Through research on the application of hydroviscous speed-adjusting clutch in belt conveyor, this paper concluded that hydroviscous speed-adjusting clutch has many advantages such as controllable start and stop, overload protection and multi-motor power equilibrium. But its theory when used in large power fan and pump could not meet the needs of belt conveyor soft-start operation. Focusing on the theo- retical analysis of the lubrication oil flow needed by the transmission procedure to form the oil-film. Put forward concrete calculation methods of lubrication flow and how to de- cide number of oil-films used in belt conveyor.展开更多
Due to low carrying capacity and short life of current ring reducer,we proposed a new planetary gearing with internal gear ring,which consisted of two stages.One was an involute planetary drive and the other was an N-...Due to low carrying capacity and short life of current ring reducer,we proposed a new planetary gearing with internal gear ring,which consisted of two stages.One was an involute planetary drive and the other was an N-type planetary drive with small teeth difference.The kinematic calculation was conducted based on the analysis of structural composition and working principle.Formulas of backlash calculation for the new planetary gearing were derived by using probabilistic theory and the analytical model was created at the same time.Then,main factors that affect the systematic backlash were introduced and the effects of manufacture error,misaligments and roller bearing parameters on the distribution of backlash were presented.The influence of gear backlash on systematic return difference was performed based on the backlash mathematic model proposed.The results show that the backlash is a little large,of which the backlash of bearing takes a greater part than two gearing stages.So we presented some practical methods to reduce the systematic backlash.展开更多
The suboptimal reliable guaranteed cost control （RGCC） with multi-criterion constraints is investigated for a class of uncertain continuous-time systems with sensor faults. A fauk model in sensors, which considers o...The suboptimal reliable guaranteed cost control （RGCC） with multi-criterion constraints is investigated for a class of uncertain continuous-time systems with sensor faults. A fauk model in sensors, which considers outage or partial degradation of sensors, is adopted. The influence of the disturbance on the quadratic stability of the closed-loop systems is analyzed. The reliable state-feedback controller is developed by a linear matrix inequalities （LMIs） approach, to minimize the upper bound of a quadratic cost fimction under the conditions that all the closed-loop poles be placed in a specified disk, and that the prescribed level of H∞ disturbance attenuation and the upper bound constraints of control inputs＇ magnitudes be guaranteed. Thus, with the above muki-criterion constraints, the resulting closed-loop system can provide satisfactory stability, transient property, a disturbance rejection level and minimized quadratic cost performance despite possible sensor faults.展开更多
Pile drivability is a key problem during the stage of design and construction installation of pile foundations. The solution to the one dimensional wave equation was used to determine the impact force at the top of a...Pile drivability is a key problem during the stage of design and construction installation of pile foundations. The solution to the one dimensional wave equation was used to determine the impact force at the top of a concrete pile for a given ram mass, cushion stiffness, and pile impedance. The kinematic equation of pile toe was established and solved based on wave equation theory. The movements of the pile top and pile toe were presented, which clearly showed the dynamic displacement, including rebound and penetration of pile top and toe. A parametric study was made with a full range of practical values of ram weight, cushion stiffness, dropheight, and pile impedance. Suggestions for optimizing the parameters were also presented. Comparisons between the results obtained by the present solution and in-situ measurements indicated the reliability and validity of the method.展开更多
To improve the safety performance of urban tunnels,the fixation transfer characteristics of drivers with different driving experience levels in urban tunnels were investigated.First,a real vehicle test was performed i...To improve the safety performance of urban tunnels,the fixation transfer characteristics of drivers with different driving experience levels in urban tunnels were investigated.First,a real vehicle test was performed in an urban tunnel,and the eye movement data of 10 drivers with different driving experience levels were collected using a Dikablis eye-tracking system.Second,the driver fixation range was divided into eight areas of visual interest by using the K-means clustering method,and the fixations in different sections of the tunnel were comparatively analyzed.Finally,on the basis of the divided areas of visual interest,fixation transfer rules and the stationary distribution characteristics of drivers with different driving experience levels on different sections of the tunnel were discussed using Markov theory.Results indicate that drivers'probability of repeated fixation is greater and that the efficiency of visual search is lower at internal sections of tunnels than in external sections.Drivers obtain information mainly from the straight upper front and straight lower front areas,and the probabilities of fixation points in these two areas at the threshold and exit sections are significantly higher than those in other sections.Relative to experienced drivers,novice drivers allocate little attention to the straight upper front area and rear-view mirrors.Hence,they have weak fixation when looking forward,and they lack experience in obtaining information on rear-approaching vehicles and controlling speed.展开更多
In this paper, we use the metric coefficients and the equation of motion obtained in the second post- Newtonian approximation of scalar-tensor theory to derive the second-order light propagation equation and the light...In this paper, we use the metric coefficients and the equation of motion obtained in the second post- Newtonian approximation of scalar-tensor theory to derive the second-order light propagation equation and the light deflection angle and compare it with previous works. These results are useful for precision astrometry missions like ASTROD, GALA, Darwin and SIM which aim at astrometry with micro-arcsecond and nano-aresecond accuracies, and need for the second post-Newtonian framework and ephemeris for observations to determine the stellar and spacecraft positions.展开更多
There is expounded the theory of＂gravitational＂ wave propagation from the volcano crater （magma） under changing density of magma mass inside the volcano. It was revealed that while the abruptly accelerated magma m...There is expounded the theory of＂gravitational＂ wave propagation from the volcano crater （magma） under changing density of magma mass inside the volcano. It was revealed that while the abruptly accelerated magma movement during starting period began eruption, the registered ＂gravitational＂ waves were being emitted and were propagating with the velocity greater than that of sound and seismic waves velocity. Alteration of ＂gravitational＂ waves velocity under the magma movement can be additional feature in prognosis of the start time of volcano eruption. The considered method might be effective when making up prognoses of underwater volcano eruption.展开更多
基金Project of China Postdoctoral Science Foundation,China (No. 2012M510982)Special Fund on the Science and Technology Innovation People of Harbin,China (No. 2011RFQXG002)+2 种基金Technology Item of Heilongjiang Provincial Education Committee,China (No.12511088)Postdoctoral Project of Heilongjiang,China (No. LBH-Z10117 )Youth Fund of Harbin University of Science and Technology,China (No. 2011YF030)
文摘In order to increase the robust performance of electro-hydraulic servo system, the system transfer function was identified by the intergration algorithm of genetic algorithm and ant colony optimization(GA-ACO), which was based on standard genetic algorithm and combined with positive feedback mechanism of ant colony algorithm. This method can obtain the precise mathematic model of continuous rotary motor which determines the order of servo system. Firstly, by constructing an appropriate fitness function, the problem of system parameters identification is converted into the problem of system parameter optimization. Secondly, in the given upper and lower bounds a set of optimal parameters are selected to meet the best approximation of the actual system. And the result shows that the identification output can trace the sampling output of actual system, and the error is very small. In addition, another set of experimental data are used to test the identification result. The result shows that the identification parameters can approach the actual system. The experimental results verify the feasibility of this method. And it is fit for the parameter identification of general complex system using the integration algorithm of GA-ACO.
文摘Through research on the application of hydroviscous speed-adjusting clutch in belt conveyor, this paper concluded that hydroviscous speed-adjusting clutch has many advantages such as controllable start and stop, overload protection and multi-motor power equilibrium. But its theory when used in large power fan and pump could not meet the needs of belt conveyor soft-start operation. Focusing on the theo- retical analysis of the lubrication oil flow needed by the transmission procedure to form the oil-film. Put forward concrete calculation methods of lubrication flow and how to de- cide number of oil-films used in belt conveyor.
基金Funded by Key Technology R&D Program of Chongqing(No. 2008AC3087)Science & Technology Project of Chongqing Education Committee(No. KJ091414)
文摘Due to low carrying capacity and short life of current ring reducer,we proposed a new planetary gearing with internal gear ring,which consisted of two stages.One was an involute planetary drive and the other was an N-type planetary drive with small teeth difference.The kinematic calculation was conducted based on the analysis of structural composition and working principle.Formulas of backlash calculation for the new planetary gearing were derived by using probabilistic theory and the analytical model was created at the same time.Then,main factors that affect the systematic backlash were introduced and the effects of manufacture error,misaligments and roller bearing parameters on the distribution of backlash were presented.The influence of gear backlash on systematic return difference was performed based on the backlash mathematic model proposed.The results show that the backlash is a little large,of which the backlash of bearing takes a greater part than two gearing stages.So we presented some practical methods to reduce the systematic backlash.
基金the National Natural Science Foundation of China (No. 60574082)the National Creative Research Groups Sci-ence Foundation of China (No. 60721062)the China Postdoc-toral Science Foundation (No. 20070411178)
文摘The suboptimal reliable guaranteed cost control （RGCC） with multi-criterion constraints is investigated for a class of uncertain continuous-time systems with sensor faults. A fauk model in sensors, which considers outage or partial degradation of sensors, is adopted. The influence of the disturbance on the quadratic stability of the closed-loop systems is analyzed. The reliable state-feedback controller is developed by a linear matrix inequalities （LMIs） approach, to minimize the upper bound of a quadratic cost fimction under the conditions that all the closed-loop poles be placed in a specified disk, and that the prescribed level of H∞ disturbance attenuation and the upper bound constraints of control inputs＇ magnitudes be guaranteed. Thus, with the above muki-criterion constraints, the resulting closed-loop system can provide satisfactory stability, transient property, a disturbance rejection level and minimized quadratic cost performance despite possible sensor faults.
文摘Pile drivability is a key problem during the stage of design and construction installation of pile foundations. The solution to the one dimensional wave equation was used to determine the impact force at the top of a concrete pile for a given ram mass, cushion stiffness, and pile impedance. The kinematic equation of pile toe was established and solved based on wave equation theory. The movements of the pile top and pile toe were presented, which clearly showed the dynamic displacement, including rebound and penetration of pile top and toe. A parametric study was made with a full range of practical values of ram weight, cushion stiffness, dropheight, and pile impedance. Suggestions for optimizing the parameters were also presented. Comparisons between the results obtained by the present solution and in-situ measurements indicated the reliability and validity of the method.
基金The National Key Research and Development Program of China(No.2019YFE0123800)the Fundamental Research Funds for the Central Universities(No.30919011290,30920010010).
文摘To improve the safety performance of urban tunnels,the fixation transfer characteristics of drivers with different driving experience levels in urban tunnels were investigated.First,a real vehicle test was performed in an urban tunnel,and the eye movement data of 10 drivers with different driving experience levels were collected using a Dikablis eye-tracking system.Second,the driver fixation range was divided into eight areas of visual interest by using the K-means clustering method,and the fixations in different sections of the tunnel were comparatively analyzed.Finally,on the basis of the divided areas of visual interest,fixation transfer rules and the stationary distribution characteristics of drivers with different driving experience levels on different sections of the tunnel were discussed using Markov theory.Results indicate that drivers'probability of repeated fixation is greater and that the efficiency of visual search is lower at internal sections of tunnels than in external sections.Drivers obtain information mainly from the straight upper front and straight lower front areas,and the probabilities of fixation points in these two areas at the threshold and exit sections are significantly higher than those in other sections.Relative to experienced drivers,novice drivers allocate little attention to the straight upper front area and rear-view mirrors.Hence,they have weak fixation when looking forward,and they lack experience in obtaining information on rear-approaching vehicles and controlling speed.
基金Supported by the National Natural Science Foundation of China under Grant No. 10875171
文摘In this paper, we use the metric coefficients and the equation of motion obtained in the second post- Newtonian approximation of scalar-tensor theory to derive the second-order light propagation equation and the light deflection angle and compare it with previous works. These results are useful for precision astrometry missions like ASTROD, GALA, Darwin and SIM which aim at astrometry with micro-arcsecond and nano-aresecond accuracies, and need for the second post-Newtonian framework and ephemeris for observations to determine the stellar and spacecraft positions.
文摘There is expounded the theory of＂gravitational＂ wave propagation from the volcano crater （magma） under changing density of magma mass inside the volcano. It was revealed that while the abruptly accelerated magma movement during starting period began eruption, the registered ＂gravitational＂ waves were being emitted and were propagating with the velocity greater than that of sound and seismic waves velocity. Alteration of ＂gravitational＂ waves velocity under the magma movement can be additional feature in prognosis of the start time of volcano eruption. The considered method might be effective when making up prognoses of underwater volcano eruption.
