Experimental investigations are made on the effects of operating conditionson the flow characteristics of throttle when tap water is used as the working media. The researchedthrottles include cone poppet valve, ball v...Experimental investigations are made on the effects of operating conditionson the flow characteristics of throttle when tap water is used as the working media. The researchedthrottles include cone poppet valve, ball valve, disc valve and dumping orifice. Operating conditionincludes poppet lift, working media, back pressure, medium temperature, etc. Because the vapourouspressure of water is much higher than that of oil, cavitation is easier to occur in water hydraulicelements and systems, so the effects of operating conditions on the cavitation characteristics ofthrottle are also researched.展开更多
In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid...In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid momentum and mass continuity, the distribution pressure function is derived by taking oil film inertia force into consideration. Damping force, clearance excitation force, interference force of different frequencies and static load are also considered in the model. Finally, the governing equations of the stability and bifurcation behaviors of the system are solved by Floquet theory. Simulation of dynamic model shows that the rigid rotor sliding bearing system can maintain stability and exhibit a Hopf bifurcation phenomenon in a certain range.展开更多
Auto anti-collision technology is one of the main research subjects of automobiles’ safety technology. Aiming at the key technology of Auto anti-collision, measuring the distance from obstacles, based on the theory o...Auto anti-collision technology is one of the main research subjects of automobiles’ safety technology. Aiming at the key technology of Auto anti-collision, measuring the distance from obstacles, based on the theory of phase laser distance ranging, Laser Diode (LD) distance-measuring system for auto anti-collision has been developed to solve the problem of on-line measuring distance technology in middle to long distance utilizing the good characteristics of LD when modulating its optical intensity and adopting typical kinds of filter techniques in this paper. By theoretical analysis, adopting typical kinds of filter techniques can reduce the interference of strong light, so distance-measuring range can be 0.5–100 m in daytime or 1–200 m at night. And more, from theoretical analysis and experiment result, it can guarantee the high measuring resolution which can be less than 24.5 mm, utilizing the method of two Laser Diode optical intensity modulating wavelength and complimenting precise calibration and revision. The idea of LD distance-measuring technology is novel and feasible and this technology can be applied in Auto anti-collision. Key words laser diode - phase laser distance ranging - filter techniques - auto anti-collision CLC number TH 161 Foundation item: Supported by the National Natural Science Foundation of China (59675080, 59805006) and Wuhan Chenguang Foundation (20025001001)Biography: Zhang Xin-bao (1965-), male, Associate professor, research direction: precise mechanism and instrument.展开更多
This paper has introduced the developments of water hydraulic axial piston equipments. According to the effects of physicochemical properties of water on water hydraulic components, a novel valve plate for water hydra...This paper has introduced the developments of water hydraulic axial piston equipments. According to the effects of physicochemical properties of water on water hydraulic components, a novel valve plate for water hydraulic axial motor has been put forward, whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely. The material screening experiment of valve plate is done on the test rig. Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied. The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively. It is evident that the appropriate structure should change the wear status between matching pairs and reduces the wear and specific pressure of the matching pairs. The specimen with the new type valve plate is used in a tool system.展开更多
This paper puts forward a machining complex oriented compensation strategy for the generalized kinematic errors (GKEs). According to this strategy, the error map, which is constructed by using the off line measuring ...This paper puts forward a machining complex oriented compensation strategy for the generalized kinematic errors (GKEs). According to this strategy, the error map, which is constructed by using the off line measuring information of the machined workpiece, is not oriented for the machine tool but for the machining complex to compensate the GKEs. The error map is derived by the proposed predictive learning control algorithm (PLCA), which is supported by the information model of machining complex. Experimental results show that the machining complex oriented GKEs compensation strategy and the information model based PLCA is effective.展开更多
Aiming at the non-linear nature of the signals generated from turbines, curvilinear component analysis (CCA), a novel nonlinear projection method that favors local topology conservation is presented for turbines condi...Aiming at the non-linear nature of the signals generated from turbines, curvilinear component analysis (CCA), a novel nonlinear projection method that favors local topology conservation is presented for turbines conditions monitoring. This is accomplished in two steps. Time domain features are extracted from raw vibration signals, and then they are projected into a two-dimensional output space by using CCA method and form regions indicative of specific conditions, which helps classify and identify turbine states visually. Therefore, the variation of turbine conditions can be observed clearly with the trajectory of image points for the feature data in the two-dimensional space, and the occurrence and development of failures can be monitored in time. Key words condition monitoring - turbines - nonlinear mapping - curvilinear component analysis CLC number TP 17 - TH 17 Foundation item: Supported by the National Key Basic Research Special Found of China (2003CB716207) and the National Natural Science Foundation of China (50375047)Biography: Liao Guang-lan (1974-), male, Ph. D. candidate, research direction: fault diagnosis, pattern recognition and neural networks.展开更多
Development of curved surface is a useful tool in CAD(computer aided design) and CAGD(computer aided geometric design).This paper presents the algorithms for developing (flattening) a smooth continuous curved surface ...Development of curved surface is a useful tool in CAD(computer aided design) and CAGD(computer aided geometric design).This paper presents the algorithms for developing (flattening) a smooth continuous curved surface embedded in three dimensional space into a planar shape. First the definition of planar development of a curved surface is presented, and the distortions (at length and area) of development are discussed in this paper. Then several planar flattening methods of curved surface, and their advantages and disadvantages are analyzed in detail. For NURBS(non uniform rational basic spline) surfaces, which are broadly used in CAGD, we put forward a new planar developing algorithm, i.e. hybrid developing, and present the steps of the algorithm. At last, some examples are used to show the effectiveness of the algorithm.展开更多
Networked Manufacturing is the trend evolution for manufacture enterprise to gain core competence in the networked economy environment. In this paper, the definition of the strategic alliance is introduced and its lif...Networked Manufacturing is the trend evolution for manufacture enterprise to gain core competence in the networked economy environment. In this paper, the definition of the strategic alliance is introduced and its life cycle is described. As the selection of suitable partners is of vital importance to the success for strategic alliance in Networked Manufacturing environment, also in this paper, the definition, criteria and process for partner selection are introduced. Then the fuzzy-AHP (Analytic Hierarchy Process) method, as a fuzzy extension of analytic hierarchical approach for partner selection, is given. In the end, a case study is provided.展开更多
A derivation of an analytical expression for the inviscid velocity fieldinduced by a single right-handed helical vortex filament is presented. The vortex filament movesuniformly and rigidly without change of form in a...A derivation of an analytical expression for the inviscid velocity fieldinduced by a single right-handed helical vortex filament is presented. The vortex filament movesuniformly and rigidly without change of form in a cylindrical tube, where the vortex filamentrotates around its axis with a constant angular velocity and translates along its axis with aconstant translational velocity. The key to solve the problem is to set up a moving cylindricalcoordinate system fixed on the vortex filament. The result shows that the velocity field is atime-periodic function, and may degenerate into Okulovs' s formula when the helical vortex filamentslips along the filament itself or stays immobile.展开更多
基金This project is supported by National Natural Science Foundation of China (No.50375056, 59975031).
文摘Experimental investigations are made on the effects of operating conditionson the flow characteristics of throttle when tap water is used as the working media. The researchedthrottles include cone poppet valve, ball valve, disc valve and dumping orifice. Operating conditionincludes poppet lift, working media, back pressure, medium temperature, etc. Because the vapourouspressure of water is much higher than that of oil, cavitation is easier to occur in water hydraulicelements and systems, so the effects of operating conditions on the cavitation characteristics ofthrottle are also researched.
文摘In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid momentum and mass continuity, the distribution pressure function is derived by taking oil film inertia force into consideration. Damping force, clearance excitation force, interference force of different frequencies and static load are also considered in the model. Finally, the governing equations of the stability and bifurcation behaviors of the system are solved by Floquet theory. Simulation of dynamic model shows that the rigid rotor sliding bearing system can maintain stability and exhibit a Hopf bifurcation phenomenon in a certain range.
文摘Auto anti-collision technology is one of the main research subjects of automobiles’ safety technology. Aiming at the key technology of Auto anti-collision, measuring the distance from obstacles, based on the theory of phase laser distance ranging, Laser Diode (LD) distance-measuring system for auto anti-collision has been developed to solve the problem of on-line measuring distance technology in middle to long distance utilizing the good characteristics of LD when modulating its optical intensity and adopting typical kinds of filter techniques in this paper. By theoretical analysis, adopting typical kinds of filter techniques can reduce the interference of strong light, so distance-measuring range can be 0.5–100 m in daytime or 1–200 m at night. And more, from theoretical analysis and experiment result, it can guarantee the high measuring resolution which can be less than 24.5 mm, utilizing the method of two Laser Diode optical intensity modulating wavelength and complimenting precise calibration and revision. The idea of LD distance-measuring technology is novel and feasible and this technology can be applied in Auto anti-collision. Key words laser diode - phase laser distance ranging - filter techniques - auto anti-collision CLC number TH 161 Foundation item: Supported by the National Natural Science Foundation of China (59675080, 59805006) and Wuhan Chenguang Foundation (20025001001)Biography: Zhang Xin-bao (1965-), male, Associate professor, research direction: precise mechanism and instrument.
文摘This paper has introduced the developments of water hydraulic axial piston equipments. According to the effects of physicochemical properties of water on water hydraulic components, a novel valve plate for water hydraulic axial motor has been put forward, whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely. The material screening experiment of valve plate is done on the test rig. Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied. The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively. It is evident that the appropriate structure should change the wear status between matching pairs and reduces the wear and specific pressure of the matching pairs. The specimen with the new type valve plate is used in a tool system.
文摘This paper puts forward a machining complex oriented compensation strategy for the generalized kinematic errors (GKEs). According to this strategy, the error map, which is constructed by using the off line measuring information of the machined workpiece, is not oriented for the machine tool but for the machining complex to compensate the GKEs. The error map is derived by the proposed predictive learning control algorithm (PLCA), which is supported by the information model of machining complex. Experimental results show that the machining complex oriented GKEs compensation strategy and the information model based PLCA is effective.
文摘Aiming at the non-linear nature of the signals generated from turbines, curvilinear component analysis (CCA), a novel nonlinear projection method that favors local topology conservation is presented for turbines conditions monitoring. This is accomplished in two steps. Time domain features are extracted from raw vibration signals, and then they are projected into a two-dimensional output space by using CCA method and form regions indicative of specific conditions, which helps classify and identify turbine states visually. Therefore, the variation of turbine conditions can be observed clearly with the trajectory of image points for the feature data in the two-dimensional space, and the occurrence and development of failures can be monitored in time. Key words condition monitoring - turbines - nonlinear mapping - curvilinear component analysis CLC number TP 17 - TH 17 Foundation item: Supported by the National Key Basic Research Special Found of China (2003CB716207) and the National Natural Science Foundation of China (50375047)Biography: Liao Guang-lan (1974-), male, Ph. D. candidate, research direction: fault diagnosis, pattern recognition and neural networks.
文摘Development of curved surface is a useful tool in CAD(computer aided design) and CAGD(computer aided geometric design).This paper presents the algorithms for developing (flattening) a smooth continuous curved surface embedded in three dimensional space into a planar shape. First the definition of planar development of a curved surface is presented, and the distortions (at length and area) of development are discussed in this paper. Then several planar flattening methods of curved surface, and their advantages and disadvantages are analyzed in detail. For NURBS(non uniform rational basic spline) surfaces, which are broadly used in CAGD, we put forward a new planar developing algorithm, i.e. hybrid developing, and present the steps of the algorithm. At last, some examples are used to show the effectiveness of the algorithm.
基金Support by National Science Foundation of China.(Grant No. 5991076861)
文摘Networked Manufacturing is the trend evolution for manufacture enterprise to gain core competence in the networked economy environment. In this paper, the definition of the strategic alliance is introduced and its life cycle is described. As the selection of suitable partners is of vital importance to the success for strategic alliance in Networked Manufacturing environment, also in this paper, the definition, criteria and process for partner selection are introduced. Then the fuzzy-AHP (Analytic Hierarchy Process) method, as a fuzzy extension of analytic hierarchical approach for partner selection, is given. In the end, a case study is provided.
文摘A derivation of an analytical expression for the inviscid velocity fieldinduced by a single right-handed helical vortex filament is presented. The vortex filament movesuniformly and rigidly without change of form in a cylindrical tube, where the vortex filamentrotates around its axis with a constant angular velocity and translates along its axis with aconstant translational velocity. The key to solve the problem is to set up a moving cylindricalcoordinate system fixed on the vortex filament. The result shows that the velocity field is atime-periodic function, and may degenerate into Okulovs' s formula when the helical vortex filamentslips along the filament itself or stays immobile.
