After a coal mine disaster,especially a gas and coal dust explosion,the space-restricted and unstructured underground terrain and explosive gas require coal mine rescue robots with good obstacle-surmounting performanc...After a coal mine disaster,especially a gas and coal dust explosion,the space-restricted and unstructured underground terrain and explosive gas require coal mine rescue robots with good obstacle-surmounting performance and explosion-proof capability. For this type of environment,we designed a mobile platform for a rocker-type coal mine rescue robot with four independent drive wheels.The composition and operational principles of the mobile platform are introduced,we discuss the flameproof design of the rocker assembly,as well as the operational principles and mechanical structure of the bevel gear differential and the main parameters are provided.Motion simulation of the differential function and condition of the robot running on virtual,uneven terrain is carried out with ADAMS.The simulation results show that the differential device can maintain the main body of the robot at an average angle between two rockers.The robot model has good operating performance.Experiments on terrain adaptability and surmounting obstacle performance of the robot prototype have been carried out.The results indicate that the prototype has good terrain adaptability and strong obstacle-surmounting performance.展开更多
A method for estimating the critical temperature of thermal explosion for energetic materials using differential scanning calorimetry (DSC) measurement is derived from the Semenov's thermal explosion theory and th...A method for estimating the critical temperature of thermal explosion for energetic materials using differential scanning calorimetry (DSC) measurement is derived from the Semenov's thermal explosion theory and the non-isothermal kinetic equation based on Harcourt-Esson's kinetic equation.The result obtained from this method coincides completely with that of the Hu-Yang-Liang-Wu method.展开更多
A typical adaptive neural control methodology is used for the rigid body model of the hypersonic vehicle. The rigid body model is divided into the altitude subsystem and the velocity subsystem. The proportional integr...A typical adaptive neural control methodology is used for the rigid body model of the hypersonic vehicle. The rigid body model is divided into the altitude subsystem and the velocity subsystem. The proportional integral differential(PID) controller is introduced to control the velocity track. The backstepping design is applied for constructing the controllers for the altitude subsystem.To avoid the explosion of differentiation from backstepping, the higher-order filter dynamic is used for replacing the virtual controller in the backstepping design steps. In the design procedure,the radial basis function(RBF) neural network is investigated to approximate the unknown nonlinear functions in the system dynamic of the hypersonic vehicle. The simulations show the effectiveness of the design method.展开更多
In this paper,we study the distribution function of the time of explosion of a stochastic differential equation modeling the length of the dominant crack due to fatigue.The main novelty is that initial condition is re...In this paper,we study the distribution function of the time of explosion of a stochastic differential equation modeling the length of the dominant crack due to fatigue.The main novelty is that initial condition is regarded as an anticipating random variable and the stochastic integral is in the forward sense.Under suitable conditions,we use the substitution formula from Russo and Vallois to find the local solution of this equation.Then,we find the law of blow up time by proving some results on barrier crossing probabilities of Brownian bridge.展开更多
Initially, Osgood used the integral ∫dr/f（r）for an unicity crite, rion to the differential equation y＇ = f（y）, f （0） = 0. The trivial solution is unique iff this integral goes to the infinite at the origin. Th...Initially, Osgood used the integral ∫dr/f（r）for an unicity crite, rion to the differential equation y＇ = f（y）, f （0） = 0. The trivial solution is unique iff this integral goes to the infinite at the origin. Then he can prove the unicity of the trivial solution of y＇ = y Ln｜Y｜, although the second member is not lipschitzian. Later, Bernfeld [1] shows that all the solutions of y＇ = f（y） do not explose iffthe same integral goes to the infinite at the infinite. Finally, we can adapt a result from the Cauchy works as follows： the trivial solution is a singular solution iffthe same integral vanishes at the origin. Using non standard analysis, we present the proofs of the different criterions and show that the Osgood integral was used by Cauchy before in the similar purpose.展开更多
Method for numerical simulation of the temperature of granule with internal heat release in a medium with random temperature fluctuations is proposed. The method utilized the solution of a system of ordinary stochasti...Method for numerical simulation of the temperature of granule with internal heat release in a medium with random temperature fluctuations is proposed. The method utilized the solution of a system of ordinary stochastic differential equations describing temperature fluctuations of the surrounding and granule. Autocorrelation function of temperature fluctuations has a finite decay time. The suggested method is verified by the comparison with exact analytical results. Random temperature behavior of granule with internal heat release qualitatively differs from the results obtained in the deterministic approach. Mean first passage time of granules temperature intersecting critical temperature is estimated at different regime parameters.展开更多
基金the National Hi-tech Research and Development Program of China for its financial support(No.2006AA04Z208).
文摘After a coal mine disaster,especially a gas and coal dust explosion,the space-restricted and unstructured underground terrain and explosive gas require coal mine rescue robots with good obstacle-surmounting performance and explosion-proof capability. For this type of environment,we designed a mobile platform for a rocker-type coal mine rescue robot with four independent drive wheels.The composition and operational principles of the mobile platform are introduced,we discuss the flameproof design of the rocker assembly,as well as the operational principles and mechanical structure of the bevel gear differential and the main parameters are provided.Motion simulation of the differential function and condition of the robot running on virtual,uneven terrain is carried out with ADAMS.The simulation results show that the differential device can maintain the main body of the robot at an average angle between two rockers.The robot model has good operating performance.Experiments on terrain adaptability and surmounting obstacle performance of the robot prototype have been carried out.The results indicate that the prototype has good terrain adaptability and strong obstacle-surmounting performance.
基金the National Natural Science Foundation of China (60975036)
文摘A method for estimating the critical temperature of thermal explosion for energetic materials using differential scanning calorimetry (DSC) measurement is derived from the Semenov's thermal explosion theory and the non-isothermal kinetic equation based on Harcourt-Esson's kinetic equation.The result obtained from this method coincides completely with that of the Hu-Yang-Liang-Wu method.
基金supported by the National Natural Science Foundation of China (61903374)。
文摘A typical adaptive neural control methodology is used for the rigid body model of the hypersonic vehicle. The rigid body model is divided into the altitude subsystem and the velocity subsystem. The proportional integral differential(PID) controller is introduced to control the velocity track. The backstepping design is applied for constructing the controllers for the altitude subsystem.To avoid the explosion of differentiation from backstepping, the higher-order filter dynamic is used for replacing the virtual controller in the backstepping design steps. In the design procedure,the radial basis function(RBF) neural network is investigated to approximate the unknown nonlinear functions in the system dynamic of the hypersonic vehicle. The simulations show the effectiveness of the design method.
文摘In this paper,we study the distribution function of the time of explosion of a stochastic differential equation modeling the length of the dominant crack due to fatigue.The main novelty is that initial condition is regarded as an anticipating random variable and the stochastic integral is in the forward sense.Under suitable conditions,we use the substitution formula from Russo and Vallois to find the local solution of this equation.Then,we find the law of blow up time by proving some results on barrier crossing probabilities of Brownian bridge.
文摘Initially, Osgood used the integral ∫dr/f（r）for an unicity crite, rion to the differential equation y＇ = f（y）, f （0） = 0. The trivial solution is unique iff this integral goes to the infinite at the origin. Then he can prove the unicity of the trivial solution of y＇ = y Ln｜Y｜, although the second member is not lipschitzian. Later, Bernfeld [1] shows that all the solutions of y＇ = f（y） do not explose iffthe same integral goes to the infinite at the infinite. Finally, we can adapt a result from the Cauchy works as follows： the trivial solution is a singular solution iffthe same integral vanishes at the origin. Using non standard analysis, we present the proofs of the different criterions and show that the Osgood integral was used by Cauchy before in the similar purpose.
文摘Method for numerical simulation of the temperature of granule with internal heat release in a medium with random temperature fluctuations is proposed. The method utilized the solution of a system of ordinary stochastic differential equations describing temperature fluctuations of the surrounding and granule. Autocorrelation function of temperature fluctuations has a finite decay time. The suggested method is verified by the comparison with exact analytical results. Random temperature behavior of granule with internal heat release qualitatively differs from the results obtained in the deterministic approach. Mean first passage time of granules temperature intersecting critical temperature is estimated at different regime parameters.
