Negative step response experimental method is used in wrist force sensor's dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor's load in working. T...Negative step response experimental method is used in wrist force sensor's dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor's load in working. This experimental method needn't special experiment equipments. Experiment's dynamic repeatability is good. So wrist force sensor's dynamic performance is suitable to be calibrated by negative step response method. A new correlation wavelet transfer method is studied. By wavelet transfer method, the signal is decomposed into two dimensional spaces of time-frequency. So the problem of negative step exciting energy concentrating in the low frequency band is solved. Correlation wavelet transfer doesn't require that wavelet primary function be orthogonal and needn't wavelet reconstruction. So analyzing efficiency is high. An experimental bench is designed and manufactured to load the wrist force sensor orthogonal excitation force/moment. A piezoelectric force sensor is used to setup soft trigger and calculate the value of negative step excitation. A wrist force sensor is calibrated. The pulse response function is calculated after negative step excitation and step response have been transformed to positive step excitation and step response. The pulse response function is transferred to frequency response function. The wrist force sensor's dynamic characteristics are identified by the frequency response function.展开更多
The design principle and the structural characters of a new sine driving system apparatus, which have been used by NPU NF-3 wind tunnel in the dynamic stall experiments on the oscillating aerofoil model from 1994, is ...The design principle and the structural characters of a new sine driving system apparatus, which have been used by NPU NF-3 wind tunnel in the dynamic stall experiments on the oscillating aerofoil model from 1994, is introduced. Some measures to improve the stability and flexibility are studied. The obvious advantages of the system are its simple structure, convenient operation and more accurate sine relationship between the attack angle and the rotating angle of the aerofoil The driving system has been proved advisable comparing with the experimental results both abroad and in many dynamic tests in NF-3 wind tunnel. It can provide guidelines for the study of the aerodynamic properties on the oscillating aerofoil.展开更多
According to the stream theory, this paper proposes a mathematical model of the dielectric recovery characteristic based on the two-temperature ionization equilibrium equation. Taking the dynamic variation of charged ...According to the stream theory, this paper proposes a mathematical model of the dielectric recovery characteristic based on the two-temperature ionization equilibrium equation. Taking the dynamic variation of charged particle's ionization and attachment into account, this model can be used in collaboration with the Coulomb collision model, which gives the relationship of the heavy particle temperature and electron temperature to calculate the electron density and temperature under different pressure and electric field conditions, so as to deliver the breakdown electric field strength under different pressure conditions. Meanwhile an experiment loop of the circuit breaker has been built to measure the breakdown voltage. It is shown that calculated results are in conformity with experiment results on the whole while results based on the stream criterion are larger than experiment results. This indicates that the mathematical model proposed here is more accurate for calculating the dielectric recovery characteristic, it is derived from the stream model with some improvement and refinement and has great significance for increasing the simulation accuracy of circuit breaker's interruption characteristic.展开更多
A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment (GRACE) K-Band Range Rate (KBRR) data based on dynamic integral approach is presented in this pa...A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment (GRACE) K-Band Range Rate (KBRR) data based on dynamic integral approach is presented in this paper. After meticulously preprocessing of the GRACE KBRR data, the root mean square of its post residuals is about 0.2 micrometers per second, and seventy-two monthly temporal solutions truncated to degree and order 60 are computed for the period from January 2003 to December 2008. After applying the combi- nation filter in WHU-Grace01s, the global temporal signals show obvious periodical change rules in the large-scale fiver basins. In terms of the degree variance, our solution is smaller at high degrees, and shows a good consistency at the rest of degrees with the Release 05 models from Center for Space Research (CSR), GeoForschungsZentrum Potsdam (GFZ) and Jet Pro- pulsion Laboratory 0PL). Compared with other published models in terms of equivalent water height distribution, our solution is consistent with those published by CSR, GFZ, JPL, Delft institute of Earth Observation and Space system (DEOS), Tongji University (Tongji), Institute of Theoretical Geodesy (ITG), Astronomical Institute in University of Bern (AIUB) and Groupe de Recherche de Geodesie Spatiale (GRGS}, which indicates that the accuracy of WHU-Grace01s has a good consistency with the previously published GRACE solutions.展开更多
Optical fibre sensor has the advantages of small size,light weight,anti⁃electromagnetic interference,and high measurement accuracy,which has important applications in research and industrial production.To design an op...Optical fibre sensor has the advantages of small size,light weight,anti⁃electromagnetic interference,and high measurement accuracy,which has important applications in research and industrial production.To design an optical fibre displacement sensor(OFBDS)with simple structure and high measurement accuracy,the unified model of the commonly used OFBDS structures was proposed and the feasibility of the intensity⁃modulation of multi⁃structural optical fibre bundles was analysed based on the arrangement characteristics of the fibre bundle end⁃face.The intensity⁃modulation characteristic of different fibre bundles was analysed,and the single coil coaxial fibre bundle was chosen as the fibre probe in this study.The sensor hardware system was designed.Lastly,the calibration experiment,temperature interference experiment,changes of measured plane surface area,and the dynamic experiment were conducted.Results showed that the sensor linear measurement range was about 3 mm,and the sensor system had excellent static and dynamic characteristics.展开更多
To accurately measure and evaluate the oil-water production profile of horizontal wells, a dynamic measurement experiment of oil-water two-phase flow in horizontal wells and numerical simulation were combined to estab...To accurately measure and evaluate the oil-water production profile of horizontal wells, a dynamic measurement experiment of oil-water two-phase flow in horizontal wells and numerical simulation were combined to establish a method for measuring the partial phase flow rate of oil-water two-phase stratified flow in horizontal wells. An experimental work was performed in horizontal oil-water two-phase flow simulation well using combination production logging tool including mini-capacitance sensor and mini-spinner. The combination tool provides a recording of holdup and velocity profiles at five different heights of the borehole cross-section. The effect of total flow rate and water-cut on the response of spinner and capacitive sensor at five measured positions were investigated. The capacitance water holdup interpolation imaging algorithm was used to determine the local fluid property and oil-water interface height, and the measured local fluid speed was combined with the numerical simulation result to establish an optimal calculation model for obtaining the partial phase flow rate of the oil-water two-phase stratified flow in the horizontal well. The calculated flow rates of five measured points are basically consistent with the experimental data, the total flow rate and water holdup from calculation are in agreement with the set values in the experiment too, suggesting that the method has high accuracy.展开更多
<div style="text-align:justify;"> The constitutive behaviors of the sintered reactive material PTFE/Al/Si, one new formulation proposed by the author, were studied systematically and found it appears s...<div style="text-align:justify;"> The constitutive behaviors of the sintered reactive material PTFE/Al/Si, one new formulation proposed by the author, were studied systematically and found it appears strain-harden, stain-rate harden and temperature-soften effects, so it is more appropriate to describe the mechanical behavior with the Johnson-Cook model. With the static and dynamic experimental results and using the nonlinear fitting method, the mechanical and physical parameters in the Johnson-Cook model were determined, which supply one basis for the future numerical simulation study. </div>展开更多
This paper presents recent developments towards efficient and reliable methods for roll damping estimation based on numerical simulations as well as model tests using the harmonic excited roll motion(HERM)technique.A ...This paper presents recent developments towards efficient and reliable methods for roll damping estimation based on numerical simulations as well as model tests using the harmonic excited roll motion(HERM)technique.A newly designed automatic roll damping estimation procedure shows the advantage of a just-in-time post processing of experimental measurement results.Real-time analysis of the measured roll damping values permits a considerable shortening of the test times.Thus,a large number of investigations can be carried out with relatively manageable effort in order to determine the roll damping behavior of different keel configurations or at operating conditions,e.g.,different sized keels or Froude numbers.In addition,HERM measurement method is applied to investigate the memory effect.For this purpose,different excitation schemes are introduced and the results are analyzed.Moreover,a study of the scale effect on the roll damping properties is conducted,in which experimental and numerical investigations are performed for two scales of a ship model.Furthermore,a method is developed that significantly reduces the effort of Reynolds average Navier-Stokes(RANS)-based simulations of roll motion.The reduction of simulation time is achieved by introducing an artificial damping.The obtained results show that the developed method is very well applicable for numerical as well as in experimental investigations.During the model tests using HERM technique,the model is free and the rudder is used to keep the straight-ahead course.The analysis of the numerical and experimental results shows that the influence of the rudder induced force and moment during HERM tests is not negligible and the contribution of the rudder must be taken into account by estimating the roll damping.Finally,a new concept is developed to investigate the parametric roll behavior of ships,which allows neglecting the consideration of the complex modelling of free surface waves in the simulations.During the RANS computations,a potential-based method is applied to compute the variation of restoring terms due the roll motion.展开更多
We introduce a geometrically reconfigurable metasurface whose artificial "atoms" will reorient within unit ceils in response to a thermal stimulus in the microwave spectrum. It can alternate between two contrasting ...We introduce a geometrically reconfigurable metasurface whose artificial "atoms" will reorient within unit ceils in response to a thermal stimulus in the microwave spectrum. It can alternate between two contrasting behaviors under different temperatures and serve as a switchable filter that allows the incident energy to be selectively transmitted or reflected with an excess of 10 dB isolation at certain frequencies for both polarizations. The ex- perimental results are consistent with the theoretical simulations, verifying the availability of an innovative method for manipulating electromagnetic waves with the merits of higher controllability for dynamic behavior and greater flexibility in the design process.展开更多
This work focuses on a comparison between three different numerical CFD methods, namely Euler-Euler, Euler-Lagrange-stochastic, and Euler-Lagrange-deterministic, to treat a dense spouted bed, A simple cold flow experi...This work focuses on a comparison between three different numerical CFD methods, namely Euler-Euler, Euler-Lagrange-stochastic, and Euler-Lagrange-deterministic, to treat a dense spouted bed, A simple cold flow experiment was used to investigate the hydrodynamics of a gas-solid flow in a three dimensional lab-scale spouted bed, In this context, two different air mass flow rates, 0,005 and 0.006 kg/s, were applied during fluidization. The experimental bed behaviour was recorded with a high-speed camera to validate the numerical predictions in terms of bubble size, bed expansion rate, and particle velocities at different reactor heights. The numerical setup was kept similar between all three modelling approaches, At both gas mass flow rates all three approaches are able to capture the overall bed expansion. However, at higher gas mass flow rates, discrepancies between experiment and simulation increase for the Euler-Euler and Euler-Lagrange-stochastic models. The Euler-Lagrange deterministic model most accurately predicts the flow pattern at both mass flow rates. The main reasons for discrepancies between simulation and experiment result from modelling of the collision and friction forces.展开更多
基金National Hi-tech Research and Development Program of China(863 Program,No.2001AA42330).
文摘Negative step response experimental method is used in wrist force sensor's dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor's load in working. This experimental method needn't special experiment equipments. Experiment's dynamic repeatability is good. So wrist force sensor's dynamic performance is suitable to be calibrated by negative step response method. A new correlation wavelet transfer method is studied. By wavelet transfer method, the signal is decomposed into two dimensional spaces of time-frequency. So the problem of negative step exciting energy concentrating in the low frequency band is solved. Correlation wavelet transfer doesn't require that wavelet primary function be orthogonal and needn't wavelet reconstruction. So analyzing efficiency is high. An experimental bench is designed and manufactured to load the wrist force sensor orthogonal excitation force/moment. A piezoelectric force sensor is used to setup soft trigger and calculate the value of negative step excitation. A wrist force sensor is calibrated. The pulse response function is calculated after negative step excitation and step response have been transformed to positive step excitation and step response. The pulse response function is transferred to frequency response function. The wrist force sensor's dynamic characteristics are identified by the frequency response function.
文摘The design principle and the structural characters of a new sine driving system apparatus, which have been used by NPU NF-3 wind tunnel in the dynamic stall experiments on the oscillating aerofoil model from 1994, is introduced. Some measures to improve the stability and flexibility are studied. The obvious advantages of the system are its simple structure, convenient operation and more accurate sine relationship between the attack angle and the rotating angle of the aerofoil The driving system has been proved advisable comparing with the experimental results both abroad and in many dynamic tests in NF-3 wind tunnel. It can provide guidelines for the study of the aerodynamic properties on the oscillating aerofoil.
基金supported by Science and Technology Project of State Grid Corporation of China(No.GY17201200063)National Natural Science Foundation of China(No.51277123)Basic Research Project of Liaoning Key Laboratory of Education Department(LZ2015055)
文摘According to the stream theory, this paper proposes a mathematical model of the dielectric recovery characteristic based on the two-temperature ionization equilibrium equation. Taking the dynamic variation of charged particle's ionization and attachment into account, this model can be used in collaboration with the Coulomb collision model, which gives the relationship of the heavy particle temperature and electron temperature to calculate the electron density and temperature under different pressure and electric field conditions, so as to deliver the breakdown electric field strength under different pressure conditions. Meanwhile an experiment loop of the circuit breaker has been built to measure the breakdown voltage. It is shown that calculated results are in conformity with experiment results on the whole while results based on the stream criterion are larger than experiment results. This indicates that the mathematical model proposed here is more accurate for calculating the dielectric recovery characteristic, it is derived from the stream model with some improvement and refinement and has great significance for increasing the simulation accuracy of circuit breaker's interruption characteristic.
基金supported by the National 973Program of China(2013CB733302)the National Natural Science Foundation of China(41131067,41174020,41374023,41474019)+2 种基金the Open Research Fund Program of the State Key Laboratory of Geodesy and Earth's Dynamics(SKLGED2015-1-3-E)the open fund of State Key Laboratory of Geographic Information Engineering(SKLGIE2013-M-1-3)the open fund of Key Laboratory of Geospace Environment and Geodesy,Ministry of Education(13-02-05)
文摘A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment (GRACE) K-Band Range Rate (KBRR) data based on dynamic integral approach is presented in this paper. After meticulously preprocessing of the GRACE KBRR data, the root mean square of its post residuals is about 0.2 micrometers per second, and seventy-two monthly temporal solutions truncated to degree and order 60 are computed for the period from January 2003 to December 2008. After applying the combi- nation filter in WHU-Grace01s, the global temporal signals show obvious periodical change rules in the large-scale fiver basins. In terms of the degree variance, our solution is smaller at high degrees, and shows a good consistency at the rest of degrees with the Release 05 models from Center for Space Research (CSR), GeoForschungsZentrum Potsdam (GFZ) and Jet Pro- pulsion Laboratory 0PL). Compared with other published models in terms of equivalent water height distribution, our solution is consistent with those published by CSR, GFZ, JPL, Delft institute of Earth Observation and Space system (DEOS), Tongji University (Tongji), Institute of Theoretical Geodesy (ITG), Astronomical Institute in University of Bern (AIUB) and Groupe de Recherche de Geodesie Spatiale (GRGS}, which indicates that the accuracy of WHU-Grace01s has a good consistency with the previously published GRACE solutions.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51775260)the Qinglan Project of Jiangsu Province(2017)of China and the Funds of Nanjing Institute of Technology(Grant No.CKJA201801).
文摘Optical fibre sensor has the advantages of small size,light weight,anti⁃electromagnetic interference,and high measurement accuracy,which has important applications in research and industrial production.To design an optical fibre displacement sensor(OFBDS)with simple structure and high measurement accuracy,the unified model of the commonly used OFBDS structures was proposed and the feasibility of the intensity⁃modulation of multi⁃structural optical fibre bundles was analysed based on the arrangement characteristics of the fibre bundle end⁃face.The intensity⁃modulation characteristic of different fibre bundles was analysed,and the single coil coaxial fibre bundle was chosen as the fibre probe in this study.The sensor hardware system was designed.Lastly,the calibration experiment,temperature interference experiment,changes of measured plane surface area,and the dynamic experiment were conducted.Results showed that the sensor linear measurement range was about 3 mm,and the sensor system had excellent static and dynamic characteristics.
基金Supported by National Natural Science Foundation of China(41474115)Open Fund of Key Laboratory of Exploration Technologies for Oil and Gas Resources(Yangtze University)Ministry of Education of China(No K2018-02)Educational Commission of Hubei Province of China(D20141302)
文摘To accurately measure and evaluate the oil-water production profile of horizontal wells, a dynamic measurement experiment of oil-water two-phase flow in horizontal wells and numerical simulation were combined to establish a method for measuring the partial phase flow rate of oil-water two-phase stratified flow in horizontal wells. An experimental work was performed in horizontal oil-water two-phase flow simulation well using combination production logging tool including mini-capacitance sensor and mini-spinner. The combination tool provides a recording of holdup and velocity profiles at five different heights of the borehole cross-section. The effect of total flow rate and water-cut on the response of spinner and capacitive sensor at five measured positions were investigated. The capacitance water holdup interpolation imaging algorithm was used to determine the local fluid property and oil-water interface height, and the measured local fluid speed was combined with the numerical simulation result to establish an optimal calculation model for obtaining the partial phase flow rate of the oil-water two-phase stratified flow in the horizontal well. The calculated flow rates of five measured points are basically consistent with the experimental data, the total flow rate and water holdup from calculation are in agreement with the set values in the experiment too, suggesting that the method has high accuracy.
文摘<div style="text-align:justify;"> The constitutive behaviors of the sintered reactive material PTFE/Al/Si, one new formulation proposed by the author, were studied systematically and found it appears strain-harden, stain-rate harden and temperature-soften effects, so it is more appropriate to describe the mechanical behavior with the Johnson-Cook model. With the static and dynamic experimental results and using the nonlinear fitting method, the mechanical and physical parameters in the Johnson-Cook model were determined, which supply one basis for the future numerical simulation study. </div>
文摘This paper presents recent developments towards efficient and reliable methods for roll damping estimation based on numerical simulations as well as model tests using the harmonic excited roll motion(HERM)technique.A newly designed automatic roll damping estimation procedure shows the advantage of a just-in-time post processing of experimental measurement results.Real-time analysis of the measured roll damping values permits a considerable shortening of the test times.Thus,a large number of investigations can be carried out with relatively manageable effort in order to determine the roll damping behavior of different keel configurations or at operating conditions,e.g.,different sized keels or Froude numbers.In addition,HERM measurement method is applied to investigate the memory effect.For this purpose,different excitation schemes are introduced and the results are analyzed.Moreover,a study of the scale effect on the roll damping properties is conducted,in which experimental and numerical investigations are performed for two scales of a ship model.Furthermore,a method is developed that significantly reduces the effort of Reynolds average Navier-Stokes(RANS)-based simulations of roll motion.The reduction of simulation time is achieved by introducing an artificial damping.The obtained results show that the developed method is very well applicable for numerical as well as in experimental investigations.During the model tests using HERM technique,the model is free and the rudder is used to keep the straight-ahead course.The analysis of the numerical and experimental results shows that the influence of the rudder induced force and moment during HERM tests is not negligible and the contribution of the rudder must be taken into account by estimating the roll damping.Finally,a new concept is developed to investigate the parametric roll behavior of ships,which allows neglecting the consideration of the complex modelling of free surface waves in the simulations.During the RANS computations,a potential-based method is applied to compute the variation of restoring terms due the roll motion.
基金supported by the National Natural Science Foundation of China(No.61401424)
文摘We introduce a geometrically reconfigurable metasurface whose artificial "atoms" will reorient within unit ceils in response to a thermal stimulus in the microwave spectrum. It can alternate between two contrasting behaviors under different temperatures and serve as a switchable filter that allows the incident energy to be selectively transmitted or reflected with an excess of 10 dB isolation at certain frequencies for both polarizations. The ex- perimental results are consistent with the theoretical simulations, verifying the availability of an innovative method for manipulating electromagnetic waves with the merits of higher controllability for dynamic behavior and greater flexibility in the design process.
基金This work was supported by the National Natural Science Foundation of China(Grant No.52006232)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2019020)。
文摘This work focuses on a comparison between three different numerical CFD methods, namely Euler-Euler, Euler-Lagrange-stochastic, and Euler-Lagrange-deterministic, to treat a dense spouted bed, A simple cold flow experiment was used to investigate the hydrodynamics of a gas-solid flow in a three dimensional lab-scale spouted bed, In this context, two different air mass flow rates, 0,005 and 0.006 kg/s, were applied during fluidization. The experimental bed behaviour was recorded with a high-speed camera to validate the numerical predictions in terms of bubble size, bed expansion rate, and particle velocities at different reactor heights. The numerical setup was kept similar between all three modelling approaches, At both gas mass flow rates all three approaches are able to capture the overall bed expansion. However, at higher gas mass flow rates, discrepancies between experiment and simulation increase for the Euler-Euler and Euler-Lagrange-stochastic models. The Euler-Lagrange deterministic model most accurately predicts the flow pattern at both mass flow rates. The main reasons for discrepancies between simulation and experiment result from modelling of the collision and friction forces.