This work focuses on motion control of high-velocity autonomous underwater vehicle(AUV).Conventional methods are effective solutions to motion control of low-and-medium-velocity AUV.Usually not taken into consideratio...This work focuses on motion control of high-velocity autonomous underwater vehicle(AUV).Conventional methods are effective solutions to motion control of low-and-medium-velocity AUV.Usually not taken into consideration in the control model,the residual dead load and damping force which vary with the AUV’s velocity tend to result in difficulties in motion control or even failure in convergence in the case of high-velocity movement.With full consideration given to the influence of residual dead load and changing damping force upon AUV motion control,a novel sliding-mode controller(SMC)is proposed in this work.The stability analysis of the proposed controller is carried out on the basis of Lyapunov function.The sea trials results proved the superiority of the sliding-mode controller over sigmoid-function-based controller(SFC).The novel controller demonstrated its effectiveness by achieving admirable control results in the case of high-velocity movement.展开更多
The dead load crown of hydraulic elastic bulging roll was discussed using the theory of elastically supported beam,and the dead load experiment was carried out. The theoretical calculation is consistent with the exper...The dead load crown of hydraulic elastic bulging roll was discussed using the theory of elastically supported beam,and the dead load experiment was carried out. The theoretical calculation is consistent with the experimental result. The structure parameters for the thickness of roll sleeve,the length of the oil groove and the crown of roll were discussed. The fundamental principle of determining the parameters was put forward. The theoretical basis of the application of the hydraulic elastic bulging roll was established.展开更多
The stress distribution of notched specimen of brittle material under a plane pressure was studied using a photoelastic meth- od,When elastic deformation appeared inside the specimen,the force transferred by dowel par...The stress distribution of notched specimen of brittle material under a plane pressure was studied using a photoelastic meth- od,When elastic deformation appeared inside the specimen,the force transferred by dowel part was triangular transverse force and frictional force on the upper surface of the sample.The quantity of the frictional force was about 31 percent of transverse force.The stress inside the sample was linear along the central cross section of the sample and there was maximum tensile stress σ_y at the tip of the notch.Basing on shearing stress deviation method,the tensile stress σ_y,σ_x and shearing stress τ_(xy) at the cen- tral sections and four adjacent cross sections were calculated.The result pointed out that σ_x and τ_(xy) were smaller than σ_y.There- fore,σ_y was the main factor for crack formation and propagation.展开更多
In order to determine the reasonable completed dead load state in earth-anchored cable-stayed bridges,a practical method is proposed. The method is based on the rigidly supported continuous beam method and the feasibl...In order to determine the reasonable completed dead load state in earth-anchored cable-stayed bridges,a practical method is proposed. The method is based on the rigidly supported continuous beam method and the feasible zone method,emphasizing on the mutual effect between the self-anchored structural parts and the earth-anchored ones. Three cable-stayed bridge models are designed with the main spans of 1 400 m,including a partially earth-anchored cable-stayed bridge,a cable-stayed-suspension bridge and a fully selfanchored cable-stayed bridge,in which the C50 concrete and Q345 steel are adopted. The partially earthanchored cable-stayed bridge and the cable-stayed-suspension bridge secure lower compressive force in the girder than the fully self-anchored cable-stayed bridge by 25 percent at least. The same is for the material consumption of the whole bridge. Furthermore,the anchor volume is more than 20% lower in the partially earthanchored cable-stayed bridge than that in the cable-stayed-suspension bridge. Consequently,the practical span of cable-stayed bridges can be accordingly extended.展开更多
The dynamic load characteristics of a proton exchange membrane fuel cell（PEMFC） with a dead-ended anode were studied. In a 70 h experiment, the effects of anode pressure, operating temperature, and relative humidity...The dynamic load characteristics of a proton exchange membrane fuel cell（PEMFC） with a dead-ended anode were studied. In a 70 h experiment, the effects of anode pressure, operating temperature, and relative humidity of the cathode on the performances of the fuel cell were investigated. The obtained results show that, with different relative humidity of the cathode at 65 ℃, dynamic loading has little effect on the performances of fuel cell and the electrochemically active surface area（ECSA）. However, the fuel cell operating under dynamic load is unstable when the relative humidity is 50%, and at 50 ℃ with 100% relative humidity, applying a dynamic load has a significant influence on the fuel cell performances. Scanning electron microscopy（SEM） showed that both the upstream and middle catalyst layers of the cell were unchanged, whereas the downstream cathode catalyst layer thinned as a response to dynamic load.展开更多
基金Project(2011AA09A106)supported by the Hi-tech Research and Development Program of ChinaProjects(51179035,51779057)supported by the National Natural Science Foundation of ChinaProject(2015ZX01041101)supported by Major National Science and Technology of China
文摘This work focuses on motion control of high-velocity autonomous underwater vehicle(AUV).Conventional methods are effective solutions to motion control of low-and-medium-velocity AUV.Usually not taken into consideration in the control model,the residual dead load and damping force which vary with the AUV’s velocity tend to result in difficulties in motion control or even failure in convergence in the case of high-velocity movement.With full consideration given to the influence of residual dead load and changing damping force upon AUV motion control,a novel sliding-mode controller(SMC)is proposed in this work.The stability analysis of the proposed controller is carried out on the basis of Lyapunov function.The sea trials results proved the superiority of the sliding-mode controller over sigmoid-function-based controller(SFC).The novel controller demonstrated its effectiveness by achieving admirable control results in the case of high-velocity movement.
基金Item Sponsored by Scientific and Technological Brainstorm Project for Ninth Five-Year Plan of China(95-528-01-04B)
文摘The dead load crown of hydraulic elastic bulging roll was discussed using the theory of elastically supported beam,and the dead load experiment was carried out. The theoretical calculation is consistent with the experimental result. The structure parameters for the thickness of roll sleeve,the length of the oil groove and the crown of roll were discussed. The fundamental principle of determining the parameters was put forward. The theoretical basis of the application of the hydraulic elastic bulging roll was established.
文摘The stress distribution of notched specimen of brittle material under a plane pressure was studied using a photoelastic meth- od,When elastic deformation appeared inside the specimen,the force transferred by dowel part was triangular transverse force and frictional force on the upper surface of the sample.The quantity of the frictional force was about 31 percent of transverse force.The stress inside the sample was linear along the central cross section of the sample and there was maximum tensile stress σ_y at the tip of the notch.Basing on shearing stress deviation method,the tensile stress σ_y,σ_x and shearing stress τ_(xy) at the cen- tral sections and four adjacent cross sections were calculated.The result pointed out that σ_x and τ_(xy) were smaller than σ_y.There- fore,σ_y was the main factor for crack formation and propagation.
基金Sponsored by the National Basic Research Program of China(Grant No.2013CB036303)the National Natural Science Foundation of China(Grant No.51008223)
文摘In order to determine the reasonable completed dead load state in earth-anchored cable-stayed bridges,a practical method is proposed. The method is based on the rigidly supported continuous beam method and the feasible zone method,emphasizing on the mutual effect between the self-anchored structural parts and the earth-anchored ones. Three cable-stayed bridge models are designed with the main spans of 1 400 m,including a partially earth-anchored cable-stayed bridge,a cable-stayed-suspension bridge and a fully selfanchored cable-stayed bridge,in which the C50 concrete and Q345 steel are adopted. The partially earthanchored cable-stayed bridge and the cable-stayed-suspension bridge secure lower compressive force in the girder than the fully self-anchored cable-stayed bridge by 25 percent at least. The same is for the material consumption of the whole bridge. Furthermore,the anchor volume is more than 20% lower in the partially earthanchored cable-stayed bridge than that in the cable-stayed-suspension bridge. Consequently,the practical span of cable-stayed bridges can be accordingly extended.
基金Funded by the National Natural Science Foundation of China(Nos.51476119 and 51576147)the Natural Science Foundation of Hubei Province(No.2016CFA041)the Fundamental Research Funds for the Central Universities(No.2017 IVA 031)
文摘The dynamic load characteristics of a proton exchange membrane fuel cell（PEMFC） with a dead-ended anode were studied. In a 70 h experiment, the effects of anode pressure, operating temperature, and relative humidity of the cathode on the performances of the fuel cell were investigated. The obtained results show that, with different relative humidity of the cathode at 65 ℃, dynamic loading has little effect on the performances of fuel cell and the electrochemically active surface area（ECSA）. However, the fuel cell operating under dynamic load is unstable when the relative humidity is 50%, and at 50 ℃ with 100% relative humidity, applying a dynamic load has a significant influence on the fuel cell performances. Scanning electron microscopy（SEM） showed that both the upstream and middle catalyst layers of the cell were unchanged, whereas the downstream cathode catalyst layer thinned as a response to dynamic load.
