In this paper,a high-accuracy 3-D deformation measurement(HADM)method with structured light is proposed and applied to wing deformation measurement in wind tunnel experiments.The present method employs an arbitrarily ...In this paper,a high-accuracy 3-D deformation measurement(HADM)method with structured light is proposed and applied to wing deformation measurement in wind tunnel experiments.The present method employs an arbitrarily arranged fringe projector and a perpendicularly placed camera.The exact phase-height mapping using the phase differences of the projected sinusoidal fringe patterns,as well as the spatial distribution of the fringe,is accurately derived.It not only presents high feasibility but also reduces systemic uncertainties arising from deviations between the ideal model and the real-world conditions.Meanwhile,a dynamic boundary process algorithm is proposed to reduce the measurement uncertainty caused by fringe fracture near the object boundary.It is calibrated that a high accuracy with the average measurement uncertainty of 0.0237 mm is achieved,which is less than 0.01%of the side length of 25 cm of the field of view.In the wind tunnel experiments,the 3-D deformations of the elastic wing,particularly the key geometric parameters such as wing tip position,angle of attack,and dihedral angle,are well reconstructed to provide an in-depth explanation for the aerodynamic characteristics.展开更多
A 3D diagnostic model including a suspended sediment transport module, ECOMSED, driven by the monthly discharge and sediment load of the Yellow River in 1983 ～ 1984, was applied to the Bohai Sea. The simulation of th...A 3D diagnostic model including a suspended sediment transport module, ECOMSED, driven by the monthly discharge and sediment load of the Yellow River in 1983 ～ 1984, was applied to the Bohai Sea. The simulation of the temporal-spatial variation of SPM （Suspended Particular Matter） concentration, sediment flux, and deposition rate was carfled out. It could be seen that, the SPM concentration exhibited distinct seasonal variation, and the variation characteristic was similar for two years. Some of the fine sediment of the Yellow River extended to the western bank of the Liaodong Bay, but most of the sediment deposited around the estuary of the Yellow River, the deposition flux rapidly decreasing with the increasing distance to the estuary. The deposition rate kept at 0.05 ～ 0.1 mm/a for most area, close to the insitu data. There were two areas of high SPM concentration in the Bohai Sea, one of which could be attributed to the Yellow River discharge, and another one, located at the seas with intensive resuspension power, to the tidal current energy. The sediment from the Yellow River was transported mainly along the track of the, Lagrangian residual cireulations. In one word, the suspended load transport was basically attributed to the wind-driven and tidal-induced Lagrangian residual circulations. The resuspenslon flux was related to the bottom currents： the larger the current speed, the more the sediment resuspended.展开更多
Natural rivers are usually winding with branches and shoals, which are difficult to be simulated with rectangular grids. A 3-D current numerical model was established based on the orthogonal curvilinear coordinate sys...Natural rivers are usually winding with branches and shoals, which are difficult to be simulated with rectangular grids. A 3-D current numerical model was established based on the orthogonal curvilinear coordinate system and vertical o coordinate system. The equations were discretisized using a semi-implicit scheme. The ＂predictor＂ and ＂corrector＂ steps were applied for the horizontal momentum equations to meet the basic requirement that the depth-integrated currents obtained from the equations for 2-D and 3-D modes have identical values. And a modification of traditional method of dry/wet discriminance was proposed to determine accurately the boundary and ensure the continuity of variable boundary in the simulation. This model was verified with the data measured in a winding tidal river with branches in April, 2004. The simulated data of water levels and velocities agree well with the measured ones, and the computed results reveal well the practical flow characteristics, including the vertical secondary flow in a winding reach.展开更多
To measure the jitter performance of the Tirthy Meter Telescope tertary mirror( TMT M3),the model of jitter based on the accerleration signal is established. First and foremost,the procedure TMT required to processs t...To measure the jitter performance of the Tirthy Meter Telescope tertary mirror( TMT M3),the model of jitter based on the accerleration signal is established. First and foremost,the procedure TMT required to processs the jitter data is presented. Then,the jitter of the system is divided into two parts: powered jitter and unpowered jitter. The metric of the jitter is required to be in the form of displacement or angle. So the frequency integration is involved to minify the error source introduced by the tending iterm in the time domain integration.In the evaluation of the power jitter,the accelerometers are used to obtain the rigid body motion of the tertiary mirror. The random decrement technique and dominated mode theory are applied to obtain the model of unpowered jitter. A classical telescope performances a 1. 6"RMS jitter metric; for a four meter scale system,the resonance frequency is around 107 Hz,powering,with 0. 14% damping. Consequently,the tip( 183 Hz,0.6%) and tilt( 193 Hz,0.19%) are both be measured. Using this model,the system engineers can estimate the unpowered jitter when the system is presented in the distortion.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12127802 and 11721202)。
文摘In this paper,a high-accuracy 3-D deformation measurement(HADM)method with structured light is proposed and applied to wing deformation measurement in wind tunnel experiments.The present method employs an arbitrarily arranged fringe projector and a perpendicularly placed camera.The exact phase-height mapping using the phase differences of the projected sinusoidal fringe patterns,as well as the spatial distribution of the fringe,is accurately derived.It not only presents high feasibility but also reduces systemic uncertainties arising from deviations between the ideal model and the real-world conditions.Meanwhile,a dynamic boundary process algorithm is proposed to reduce the measurement uncertainty caused by fringe fracture near the object boundary.It is calibrated that a high accuracy with the average measurement uncertainty of 0.0237 mm is achieved,which is less than 0.01%of the side length of 25 cm of the field of view.In the wind tunnel experiments,the 3-D deformations of the elastic wing,particularly the key geometric parameters such as wing tip position,angle of attack,and dihedral angle,are well reconstructed to provide an in-depth explanation for the aerodynamic characteristics.
基金This paper was financiallysupported by the National Natural Science Foundation of China (Grant Nos .40271020 and40571020)
文摘A 3D diagnostic model including a suspended sediment transport module, ECOMSED, driven by the monthly discharge and sediment load of the Yellow River in 1983 ～ 1984, was applied to the Bohai Sea. The simulation of the temporal-spatial variation of SPM （Suspended Particular Matter） concentration, sediment flux, and deposition rate was carfled out. It could be seen that, the SPM concentration exhibited distinct seasonal variation, and the variation characteristic was similar for two years. Some of the fine sediment of the Yellow River extended to the western bank of the Liaodong Bay, but most of the sediment deposited around the estuary of the Yellow River, the deposition flux rapidly decreasing with the increasing distance to the estuary. The deposition rate kept at 0.05 ～ 0.1 mm/a for most area, close to the insitu data. There were two areas of high SPM concentration in the Bohai Sea, one of which could be attributed to the Yellow River discharge, and another one, located at the seas with intensive resuspension power, to the tidal current energy. The sediment from the Yellow River was transported mainly along the track of the, Lagrangian residual cireulations. In one word, the suspended load transport was basically attributed to the wind-driven and tidal-induced Lagrangian residual circulations. The resuspenslon flux was related to the bottom currents： the larger the current speed, the more the sediment resuspended.
文摘Natural rivers are usually winding with branches and shoals, which are difficult to be simulated with rectangular grids. A 3-D current numerical model was established based on the orthogonal curvilinear coordinate system and vertical o coordinate system. The equations were discretisized using a semi-implicit scheme. The ＂predictor＂ and ＂corrector＂ steps were applied for the horizontal momentum equations to meet the basic requirement that the depth-integrated currents obtained from the equations for 2-D and 3-D modes have identical values. And a modification of traditional method of dry/wet discriminance was proposed to determine accurately the boundary and ensure the continuity of variable boundary in the simulation. This model was verified with the data measured in a winding tidal river with branches in April, 2004. The simulated data of water levels and velocities agree well with the measured ones, and the computed results reveal well the practical flow characteristics, including the vertical secondary flow in a winding reach.
基金Sponsored by the National Natural Science Foundation of China(Grant No.11403022)
文摘To measure the jitter performance of the Tirthy Meter Telescope tertary mirror( TMT M3),the model of jitter based on the accerleration signal is established. First and foremost,the procedure TMT required to processs the jitter data is presented. Then,the jitter of the system is divided into two parts: powered jitter and unpowered jitter. The metric of the jitter is required to be in the form of displacement or angle. So the frequency integration is involved to minify the error source introduced by the tending iterm in the time domain integration.In the evaluation of the power jitter,the accelerometers are used to obtain the rigid body motion of the tertiary mirror. The random decrement technique and dominated mode theory are applied to obtain the model of unpowered jitter. A classical telescope performances a 1. 6"RMS jitter metric; for a four meter scale system,the resonance frequency is around 107 Hz,powering,with 0. 14% damping. Consequently,the tip( 183 Hz,0.6%) and tilt( 193 Hz,0.19%) are both be measured. Using this model,the system engineers can estimate the unpowered jitter when the system is presented in the distortion.
