An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-p...An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-phase sandy medium under water level fluctuation. Three-electrode electrical conductivity probe （ECP） was used to measure water saturation. Hydrophobic tensiometer was obtained by spraying waterproof material to the ceramic cup of commercially available hydrophilic tensiometer. A couple of hydrophilic tensiometer and hydrophobic tensiometer were used to measure pore water pressure and pore LNAPL pressure of the sandy medium, respectively. All the signals from ECP and tensiometer were collected by a data taker connected with a computer. The results show that this method can finish the measurement of S-R relation of a complete drainage or imbibition process in less than 60 min. It is much more timesaving compared with 10-40 d of traditional methods. Two cycles of water level fluctuation were produced, and four saturation-capillary pressure relations including two stable residual LNAPL saturations of the sandy medium were obtained during in 350 h. The results show that this method has a good durable performance and feasibility in the porous medium with complicated multiphase flow. Although further studies are needed on the signal stability and accuracy drift of the ECP, this online dynamic method can be used successfully in the rapid characterization of a LNAPL migration in porous media.展开更多
Sea-based rocket launches encounter significant challenges stemming from dynamic marine environmental interactions.During the hot launch phase,characterized by low-velocity ascent,the departure of the rocket from the ...Sea-based rocket launches encounter significant challenges stemming from dynamic marine environmental interactions.During the hot launch phase,characterized by low-velocity ascent,the departure of the rocket from the oscillatory platform exhibits heightened sensitivity to external disturbances.In the development stage,assessing the launch dynamics and the clearance between the rocket and framed launcher are crucial for improving the reliability of sea-based rocket launches in rough sea conditions.This study presents a high-fidelity dynamic model of maritime hot launch system,demonstrating 3.21%prediction error through rigorous validation against experimental datasets from comprehensive modal analyses and the full-scale rocket flight test.To mitigate collision risks,we develop a computational method employing spatial vector analysis for dynamic measurement of rocket-launcher clearance during departure.Systematic investigations reveal that in rough sea conditions,optimal departure dynamics are achieved at θ_(thrust)=270°nozzle azimuth configuration,reducing failure probability compared to conventional orientations.The developed assessment framework not only resolves critical safety challenges in current sea launch systems but also establishes foundational principles for optimizing adapter axial configuration patterns in future designs.展开更多
In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket’s departure ...In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket’s departure from the muzzle)and the muzzle velocity are measured.Compared with the classical methods,the actual muzzle time is obtained by eliminating the ignition delay.The comparative analysis method is proposed with numerical simulations established by the transfer matrix method for multibody systems.The experiment results indicate that the proposed measurement system can effectively measure the actual muzzle time and reduce the error of classical methods,which match well with the simulation results showing the launch dynamics model is reliable and helpful for further analysis and design of the MLRS.展开更多
Based on laser-scanned measuring technology, a met ho d of on-line dynamic non-contact measurement and feedback control of processin g dimension, i.e. the double edges laser-scanned large diameter on-line dynami c mea...Based on laser-scanned measuring technology, a met ho d of on-line dynamic non-contact measurement and feedback control of processin g dimension, i.e. the double edges laser-scanned large diameter on-line dynami c measurement and control system is presented, which can be used to measure diam eter in large-scale machine part processing. In this paper, the working princip le, overall structure and microcomputer real-time control and data processing s ystem of the system are discussed in detail, the method of double edges scanned large diameter dimension measurement and control is theoretically analyzed, its possibility has been verified by experiments of lathing large diameters machine parts by a vertical lathe. The system adopts the measuring scheme of double edge s laser-scanned combined with grating displacement measurement. The two edges c haracteristic information of the measured diameter is given by the double edges laser-scanned measuring system, the non-contact measurement of large diameter dimension is realized to combine with the grating displacement measuring systems . The main controller gives out feedback control signal by means of measured res ults, and controls advance and retreat of lathe tool by the servo-control syste m of a vertical lathe to realize on-line dynamic non-contact measurement and c ontrol in processing.展开更多
基金Project(8151027501000008) supported by Guangdong Natural Science Foundation, ChinaProject(2007490511) supported by the Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, ChinaProject (2006K0006) supported by the Open Foundation of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, China
文摘An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-phase sandy medium under water level fluctuation. Three-electrode electrical conductivity probe （ECP） was used to measure water saturation. Hydrophobic tensiometer was obtained by spraying waterproof material to the ceramic cup of commercially available hydrophilic tensiometer. A couple of hydrophilic tensiometer and hydrophobic tensiometer were used to measure pore water pressure and pore LNAPL pressure of the sandy medium, respectively. All the signals from ECP and tensiometer were collected by a data taker connected with a computer. The results show that this method can finish the measurement of S-R relation of a complete drainage or imbibition process in less than 60 min. It is much more timesaving compared with 10-40 d of traditional methods. Two cycles of water level fluctuation were produced, and four saturation-capillary pressure relations including two stable residual LNAPL saturations of the sandy medium were obtained during in 350 h. The results show that this method has a good durable performance and feasibility in the porous medium with complicated multiphase flow. Although further studies are needed on the signal stability and accuracy drift of the ECP, this online dynamic method can be used successfully in the rapid characterization of a LNAPL migration in porous media.
基金the experimental technology support provided by the China Academy of Launch Vehicle Technology
文摘Sea-based rocket launches encounter significant challenges stemming from dynamic marine environmental interactions.During the hot launch phase,characterized by low-velocity ascent,the departure of the rocket from the oscillatory platform exhibits heightened sensitivity to external disturbances.In the development stage,assessing the launch dynamics and the clearance between the rocket and framed launcher are crucial for improving the reliability of sea-based rocket launches in rough sea conditions.This study presents a high-fidelity dynamic model of maritime hot launch system,demonstrating 3.21%prediction error through rigorous validation against experimental datasets from comprehensive modal analyses and the full-scale rocket flight test.To mitigate collision risks,we develop a computational method employing spatial vector analysis for dynamic measurement of rocket-launcher clearance during departure.Systematic investigations reveal that in rough sea conditions,optimal departure dynamics are achieved at θ_(thrust)=270°nozzle azimuth configuration,reducing failure probability compared to conventional orientations.The developed assessment framework not only resolves critical safety challenges in current sea launch systems but also establishes foundational principles for optimizing adapter axial configuration patterns in future designs.
文摘In this paper,a novel launch dynamics measurement system based on the photoelectric sensor pair is built.The actual muzzle time(i.e.a time duration that originates from the initial movement to the rocket’s departure from the muzzle)and the muzzle velocity are measured.Compared with the classical methods,the actual muzzle time is obtained by eliminating the ignition delay.The comparative analysis method is proposed with numerical simulations established by the transfer matrix method for multibody systems.The experiment results indicate that the proposed measurement system can effectively measure the actual muzzle time and reduce the error of classical methods,which match well with the simulation results showing the launch dynamics model is reliable and helpful for further analysis and design of the MLRS.
文摘Based on laser-scanned measuring technology, a met ho d of on-line dynamic non-contact measurement and feedback control of processin g dimension, i.e. the double edges laser-scanned large diameter on-line dynami c measurement and control system is presented, which can be used to measure diam eter in large-scale machine part processing. In this paper, the working princip le, overall structure and microcomputer real-time control and data processing s ystem of the system are discussed in detail, the method of double edges scanned large diameter dimension measurement and control is theoretically analyzed, its possibility has been verified by experiments of lathing large diameters machine parts by a vertical lathe. The system adopts the measuring scheme of double edge s laser-scanned combined with grating displacement measurement. The two edges c haracteristic information of the measured diameter is given by the double edges laser-scanned measuring system, the non-contact measurement of large diameter dimension is realized to combine with the grating displacement measuring systems . The main controller gives out feedback control signal by means of measured res ults, and controls advance and retreat of lathe tool by the servo-control syste m of a vertical lathe to realize on-line dynamic non-contact measurement and c ontrol in processing.
