Based on the evaluation of advantages and disadvantages of high-precision digital time interval measuring algorithms, and combined with the principle of the typical time-difference ultrasonic flow measurement, the req...Based on the evaluation of advantages and disadvantages of high-precision digital time interval measuring algorithms, and combined with the principle of the typical time-difference ultrasonic flow measurement, the requirements for the measurement of echo time of flight put forward by the ultrasonic flow measurement are analyzed. A new high-precision time interval measurement algorithm is presented, which combines the pulse counting method with the phase delay interpolation. The pulse counting method is used to ensure a large dynamic measuring range, and a double-edge triggering counter is designed to improve the accuracy and reduce the counting quantization error. The phase delay interpolation is used to reduce the quantization error of pulse counting for further improving the time measurement resolution. Test data show that the systexn for the measurement of the ultrasonic echo time of flight based on this algorithm and implemented on an Field Programmable Gate Army(FleA) needs a relatively short time for measurement, and has a measurement error of less than 105 ps.展开更多
Phase measuring deflectometry(PMD)is a robust,noncoherent technique for the characterization of specular surface.For measuring high specular reflectivity surface,PMD can deliver micron radian range local gradient.Howe...Phase measuring deflectometry(PMD)is a robust,noncoherent technique for the characterization of specular surface.For measuring high specular reflectivity surface,PMD can deliver micron radian range local gradient.However,when the measured surface has low specular reflectivity,the accuracy of the measured gradient is low since the captured fringe pattern shows low signal to noise ratio.The phase error characteristics in PMD system when testing low reflectivity surfaces are analyzed.The analysis illustrates that the random phase error increases rapidly while the nonlinear error drops slowly with the decreasing of the tested surface reflectivity.In order to attain high precision measurement of low reflectivity specular surface,a robust error reduction method based on wavelet de-noising is proposed to reduce the phase error.This error reduction method is compared with several other normally used methods in both simulation and experiment work.The method based on the wavelet de-noising shows better performance when measuring the low reflectivity specular surface.展开更多
To realize high-precision automatic measurement of two-dimensional geometric features on parts, a cooperative measurement system based on machine vision is constructed. Its hardware structure, functional composition a...To realize high-precision automatic measurement of two-dimensional geometric features on parts, a cooperative measurement system based on machine vision is constructed. Its hardware structure, functional composition and working principle are introduced. The mapping relationship between the feature image coordinates and the measuring space coordinates is established. The method of measuring path planning of small field of view (FOV) images is proposed. With the cooperation of the panoramic image of the object to be measured, the small FOV images with high object plane resolution are acquired automatically. Then, the auxiliary measuring characteristics are constructed and the parameters of the features to be measured are automatically extracted. Experimental results show that the absolute value of relative error is less than 0. 03% when applying the cooperative measurement system to gauge the hole distance of 100 mm nominal size. When the object plane resolving power of the small FOV images is 16 times that of the large FOV image, the measurement accuracy of small FOV images is improved by 14 times compared with the large FOV image. It is suitable for high-precision automatic measurement of two-dimensional complex geometric features distributed on large scale parts.展开更多
A phase-derived velocity measurement method is proposed in a wideband coherent system,based on a precise echo model considering the inner pulse Doppler effect caused by fast moving targets.The Cramer-Rao low band of v...A phase-derived velocity measurement method is proposed in a wideband coherent system,based on a precise echo model considering the inner pulse Doppler effect caused by fast moving targets.The Cramer-Rao low band of velocity measurement precision is deduced,demonstrating the high precision of the proposed method.Simulations and out-field experiments further validate the effectiveness of the proposed method in high-precision measurement and micro-motion extraction for targets with weak reflection intensity.Compared with the long-time integration approaches for velocity measurement,the phase-derived method is easy to implement and meets the requirement for high data rate,which makes it suitable for micro-motion feature extraction in wideband systems.展开更多
Multi-sensor coordinate unification in dimensional metrology is used in order to get holistic, more accurate and reliable information about a workpiece based on several or multiple measurement values from ...Multi-sensor coordinate unification in dimensional metrology is used in order to get holistic, more accurate and reliable information about a workpiece based on several or multiple measurement values from one or more sensors. Because of the problem that standard ball is deficient as a standard artifact in the coordinate unification of high-precision composite measurement in two dimensions (2D) , a new method is proposed in this paper which uses angle gauge blocks as standard artifacts to achieve coordinate unification between the image sensor and the tactile probe. By comparing the standard ball with the angle gauge block as a standard artifact, theoretical analysis and experimental results are given to prove that it is more precise and more convenient to use angle gauge blocks as standard artifacts to achieve coordinate unification of high-precision composite measurement in two dimensions.展开更多
Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stre...Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stress,the three-dimensional(3D)stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted,a newly defined characteristic parameter C_(ERP)was proposed as an indicator for evaluating the structural properties of rock masses,and a fuzzy relation matrix was established using the information distribution method.The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth.There is no remarkable correlation between the elastic modulus,Poisson's ratio and depth,and the distribution of data points is scattered and messy.Moreover,there is no obvious relationship between the rock quality designation(RQD)and depth.The maximum horizontal stress σ_(H) is a function of rock properties,showing a certain linear relationship with the C_(ERP)at the same depth.In addition,the overall change trend of σ_(H) determined by the established fuzzy identification method is to increase with the increase of C_(ERP).The fuzzy identification method also demonstrates a relatively detailed local relationship betweenσ_H and C_(ERP),and the predicted curve rises in a fluctuating way,which is in accord well with the measured stress data.展开更多
It is significant for establishing gravity datum to construct precise gravity solid tidal model,A simple method with relatively low performance is to interpolate tidal parameters from the global gravity solid tide mod...It is significant for establishing gravity datum to construct precise gravity solid tidal model,A simple method with relatively low performance is to interpolate tidal parameters from the global gravity solid tide models.A competitive approach is to determine local gravity solid tidal model by harmonic analysis using long-time serial gravity observations.In this paper a new high-precision gravity solid tidal model for Precision Gravity Measurement Facility is estimated from two co-site gravimeters in the cave laboratory using modern international standard data processing techniques,whose accuracy is evaluated further by comparing with previous publications.The results show that:(1)the determined gravity solid tidal models from two co-site gravimeters are in good agreement with each other,of which the maximum differences for amplitude factors and phase delays don’t exceed 0.01700%and 2.50990°,respectively.(2)the performance of the obtained gravity solid tidal model is 0.00411 for amplitude factors and 0.24120°for phase delays,which is a little better than that of previous publications using superconducting gravity data from Wuhan station.(3)our results and methods are corrective and effective.(4)our model is tiny different from that provided by Wuhan station,which implies that it is necessary to construct a gravity solid tidal model for Precision Gravity Measurement Facility,rather than just adopting existing models at Wuhan station.Our results are helpful in realizing the goal of Precision Gravity Measurement Facility.展开更多
In order to achieve high precision measurement of inductance in a wide frequency range,a method of inductance measurement based on double-excitation auto-balancing bridge is proposed.In this method,the direct digital ...In order to achieve high precision measurement of inductance in a wide frequency range,a method of inductance measurement based on double-excitation auto-balancing bridge is proposed.In this method,the direct digital synthesizer(DDS)as signal generator is used as the bridge excitation source,and the bridge is automatically balanced by adjusting and measuring the voltage ratio.Using standard resistors,the system can achieve high precision measurement of four-terminal pair inductors in the frequency range of 100Hz-100kHz.Aiming at the low efficiency of bridge balancing,an iterative balancing algorithm based on the steepest descent method is proposed.In order to suppress the interference caused by the initial phase change and non-integer periodic sampling,the high-precision measurement of the complex impedance of inductance is realized based on the all-phase fast Fourier transform(apFFT).Finally,the corresponding measurement system is built and the inductance measurement experiment is carried out.The experimental results show that the relative error of the system for inductance measurement can be as low as 0.009%,and the optimal relative measurement uncertainty of the system can reach 9.89×10^(-4)compared with 5×10^(-5)of commercial impedance analyzer.展开更多
From 2019 to 2021,China Seismic Experimental Site has built twelve 300 m deep well multi-measurement comprehensive observation stations in the cross-fault area of the Aninghe-Zemuhe fault zone,integrating BBVS120 very...From 2019 to 2021,China Seismic Experimental Site has built twelve 300 m deep well multi-measurement comprehensive observation stations in the cross-fault area of the Aninghe-Zemuhe fault zone,integrating BBVS120 very broadband borehole seismometer,RZB four-gauge borehole strainmeter and geothermometer with resolution up to 0.0001℃.The borehole diameter is 150 mm and the inner diameter of the sleeve is 130 mm.The multi-item integrated observation system is divided into two parts:underground and surface.The downhole part is mainly composed of sensor and power supply signal isolation.展开更多
In order to accurately measure an object’s three-dimensional surface shape,the influence of sampling on it was studied.First,on the basis of deriving spectra expressions through the Fourier transform,the generation o...In order to accurately measure an object’s three-dimensional surface shape,the influence of sampling on it was studied.First,on the basis of deriving spectra expressions through the Fourier transform,the generation of CCD pixels was analyzed,and its expression was given.Then,based on the discrete expression of deformation fringes obtained after sampling,its Fourier spectrum expression was derived,resulting in an infinitely repeated"spectra island"in the frequency domain.Finally,on the basis of using a low-pass filter to remove high-order harmonic components and retaining only one fundamental frequency component,the inverse Fourier transform was used to reconstruct the signal strength.A method of reducing the sampling interval,i.e.,reducing the number of sampling points per fringe,was proposed to increase the ratio between the sampling frequency and the fundamental frequency of the grating.This was done to reconstruct the object’s surface shape more accurately under the condition of m>4.The basic principle was verified through simulation and experiment.In the simulation,the sampling intervals were 8 pixels,4 pixels,2 pixels,and 1 pixel,the maximum absolute error values obtained in the last three situations were 88.80%,38.38%,and 31.50%in the first situation,respectively,and the corresponding average absolute error values are 71.84%,43.27%,and 32.26%.It is demonstrated that the smaller the sampling interval,the better the recovery effect.Taking the same four sampling intervals in the experiment as in the simulation can also lead to the same conclusions.The simulated and experimental results show that reducing the sampling interval can improve the accuracy of object surface shape measurement and achieve better reconstruction results.展开更多
This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch si...This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch signal to obtain bunch-by-bunch and turn-by-turn longitudinal parameters,such as bunch length and synchronous phase.The bunch signal is obtained using a button electrode with a bandwidth of several gigahertz.The data acquisition device was a high-speed digital oscilloscope with a sampling rate of more than 10 GS/s,and the single-shot sampling data buffer covered thousands of turns.The bunch-length and synchronous phase information were extracted via offline calculations using Python scripts.The calibration coefficient of the system was determined using a commercial streak camera.Moreover,this technique was tested on two different storage rings and successfully captured various longitudinal transient processes during the harmonic cavity debugging process at the Shanghai Synchrotron Radiation Facility(SSRF),and longitudinal instabilities were observed during the single-bunch accumulation process at Hefei Light Source(HLS).For Gaussian-distribution bunches,the uncertainty of the bunch phase obtained using this technique was better than 0.2 ps,and the bunch-length uncertainty was better than 1 ps.The dynamic range exceeded 10 ms.This technology is a powerful and versatile beam diagnostic tool that can be conveniently deployed in high-energy electron storage rings.展开更多
A new measurement device,consisting of swirling blades and capsule-shaped throttling elements,is proposed in this study to eliminate typical measurement errors caused by complex flow patterns in gas-liquid flow.The sw...A new measurement device,consisting of swirling blades and capsule-shaped throttling elements,is proposed in this study to eliminate typical measurement errors caused by complex flow patterns in gas-liquid flow.The swirling blades are used to transform the complex flow pattern into a forced annular flow.Drawing on the research of existing blockage flow meters and also exploiting the single-phase flow measurement theory,a formula is introduced to measure the phase-separated flow of gas and liquid.The formula requires the pressure ratio,Lockhart-Martinelli number(L-M number),and the gas phase Froude number.The unknown parameters appearing in the formula are fitted through numerical simulation using computational fluid dynamics(CFD),which involves a comprehensive analysis of the flow field inside the device from multiple perspectives,and takes into account the influence of pressure fluctuations.Finally,the measurement model is validated through an experimental error analysis.The results demonstrate that the measurement error can be maintained within±8%for various flow patterns,including stratified flow,bubble flow,and wave flow.展开更多
The application of Intelligent Internet of Things(IIoT)in constructing distribution station areas strongly supports platform transformation,upgrade,and intelligent integration.The sensing layer of IIoT comprises the e...The application of Intelligent Internet of Things(IIoT)in constructing distribution station areas strongly supports platform transformation,upgrade,and intelligent integration.The sensing layer of IIoT comprises the edge convergence layer and the end sensing layer,with the former using intelligent fusion terminals for real-time data collection and processing.However,the influx of multiple low-voltage in the smart grid raises higher demands for the performance,energy efficiency,and response speed of the substation fusion terminals.Simultaneously,it brings significant security risks to the entire distribution substation,posing a major challenge to the smart grid.In response to these challenges,a proposed dynamic and energy-efficient trust measurement scheme for smart grids aims to address these issues.The scheme begins by establishing a hierarchical trust measurement model,elucidating the trust relationships among smart IoT terminals.It then incorporates multidimensional measurement factors,encompassing static environmental factors,dynamic behaviors,and energy states.This comprehensive approach reduces the impact of subjective factors on trust measurements.Additionally,the scheme incorporates a detection process designed for identifying malicious low-voltage end sensing units,ensuring the prompt identification and elimination of any malicious terminals.This,in turn,enhances the security and reliability of the smart grid environment.The effectiveness of the proposed scheme in pinpointing malicious nodes has been demonstrated through simulation experiments.Notably,the scheme outperforms established trust metric models in terms of energy efficiency,showcasing its significant contribution to the field.展开更多
Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted ...Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection.展开更多
It remains a great challenge to understand the hydrates involved in phenomena in practical oil and gas systems.The adhesion forces between hydrate particles,between hydrate particles and pipe walls,and between hydrate...It remains a great challenge to understand the hydrates involved in phenomena in practical oil and gas systems.The adhesion forces between hydrate particles,between hydrate particles and pipe walls,and between hydrate particles and reservoir particles are essential factors that control the behaviors of clathrate hydrates in different applications.In this review,we summarize the typical micro-force measurement apparatus and methods utilized to study hydrate particle systems.In addition,the adhesion test results,the related understandings,and the applied numerical calculation models are systematically discussed.展开更多
In this paper,an improved spatio-temporal alignment measurement method is presented to address the inertial matching measurement of hull deformation under the coexistence of time delay and large misalignment angle.Lar...In this paper,an improved spatio-temporal alignment measurement method is presented to address the inertial matching measurement of hull deformation under the coexistence of time delay and large misalignment angle.Large misalignment angle and time delay often occur simultaneously and bring great challenges to the accurate measurement of hull deformation in space and time.The proposed method utilizes coarse alignment with large misalignment angle and time delay estimation of inertial measurement unit modeling to establish a brand-new spatiotemporal aligned hull deformation measurement model.In addition,two-step loop control is designed to ensure the accurate description of dynamic deformation angle and static deformation angle by the time-space alignment method of hull deformation.The experiments illustrate that the proposed method can effectively measure the hull deformation angle when time delay and large misalignment angle coexist.展开更多
The measurement and mapping of objects in the outer environment have traditionally been conducted using ground-based monitoring systems,as well as satellites.More recently,unmanned aerial vehicles have also been emplo...The measurement and mapping of objects in the outer environment have traditionally been conducted using ground-based monitoring systems,as well as satellites.More recently,unmanned aerial vehicles have also been employed for this purpose.The accurate detection and mapping of a target such as buildings,trees,and terrains are of utmost importance in various applications of unmanned aerial vehicles(UAVs),including search and rescue operations,object transportation,object detection,inspection tasks,and mapping activities.However,the rapid measurement and mapping of the object are not currently achievable due to factors such as the object’s size,the intricate nature of the sites,and the complexity of mapping algorithms.The present system introduces a costeffective solution for measurement and mapping by utilizing a small unmanned aerial vehicle(UAV)equipped with an 8-beam Light Detection and Ranging(LiDAR)system.This approach offers advantages over traditional methods that rely on expensive cameras and complex algorithm-based approaches.The reflective properties of laser beams have also been investigated.The system provides prompt results in comparison to traditional camerabased surveillance,with minimal latency and the need for complex algorithms.The Kalman estimation method demonstrates improved performance in the presence of noise.The measurement and mapping of external objects have been successfully conducted at varying distances,utilizing different resolutions.展开更多
The vibration interference of the reference corner cube runs through the free flight process of the free-falling corner cube,which is superimposed on the whole laser interference fringes.Thus,it is necessary to solve ...The vibration interference of the reference corner cube runs through the free flight process of the free-falling corner cube,which is superimposed on the whole laser interference fringes.Thus,it is necessary to solve the interference fringes with the entire fringe to analyze the quantitative influence of vibration on gravity measurements.展开更多
This study aims to improve the accuracy and safety of steel plate thickness calibration.A differential noncontact thickness measurement calibration system based on laser displacement sensors was designed to address th...This study aims to improve the accuracy and safety of steel plate thickness calibration.A differential noncontact thickness measurement calibration system based on laser displacement sensors was designed to address the problems of low precision of traditional contact thickness gauges and radiation risks of radiation-based thickness gauges.First,the measurement method and measurement structure of the thickness calibration system were introduced.Then,the hardware circuit of the thickness system was established based on the STM32 core chip.Finally,the system software was designed to implement system control to filter algorithms and human-computer interaction.Experiments have proven the excellent performance of the differential noncontact thickness measurement calibration system based on laser displacement sensors,which not only considerably improves measurement accuracy but also effectively reduces safety risks during the measurement process.The system offers guiding significance and application value in the field of steel plate production and processing.展开更多
Owing to the complex lithology of unconventional reservoirs,field interpreters usually need to provide a basis for interpretation using logging simulation models.Among the various detection tools that use nuclear sour...Owing to the complex lithology of unconventional reservoirs,field interpreters usually need to provide a basis for interpretation using logging simulation models.Among the various detection tools that use nuclear sources,the detector response can reflect various types of information of the medium.The Monte Carlo method is one of the primary methods used to obtain nuclear detection responses in complex environments.However,this requires a computational process with extensive random sampling,consumes considerable resources,and does not provide real-time response results.Therefore,a novel fast forward computational method(FFCM)for nuclear measurement that uses volumetric detection constraints to rapidly calculate the detector response in various complex environments is proposed.First,the data library required for the FFCM is built by collecting the detection volume,detector counts,and flux sensitivity functions through a Monte Carlo simulation.Then,based on perturbation theory and the Rytov approximation,a model for the detector response is derived using the flux sensitivity function method and a one-group diffusion model.The environmental perturbation is constrained to optimize the model according to the tool structure and the impact of the formation and borehole within the effective detection volume.Finally,the method is applied to a neutron porosity tool for verification.In various complex simulation environments,the maximum relative error between the calculated porosity results of Monte Carlo and FFCM was 6.80%,with a rootmean-square error of 0.62 p.u.In field well applications,the formation porosity model obtained using FFCM was in good agreement with the model obtained by interpreters,which demonstrates the validity and accuracy of the proposed method.展开更多
基金supported by the National 863 Program(No.2008AA042207)
文摘Based on the evaluation of advantages and disadvantages of high-precision digital time interval measuring algorithms, and combined with the principle of the typical time-difference ultrasonic flow measurement, the requirements for the measurement of echo time of flight put forward by the ultrasonic flow measurement are analyzed. A new high-precision time interval measurement algorithm is presented, which combines the pulse counting method with the phase delay interpolation. The pulse counting method is used to ensure a large dynamic measuring range, and a double-edge triggering counter is designed to improve the accuracy and reduce the counting quantization error. The phase delay interpolation is used to reduce the quantization error of pulse counting for further improving the time measurement resolution. Test data show that the systexn for the measurement of the ultrasonic echo time of flight based on this algorithm and implemented on an Field Programmable Gate Army(FleA) needs a relatively short time for measurement, and has a measurement error of less than 105 ps.
基金support by the National Nature Science Foundation of China (61421002, 61327004)
文摘Phase measuring deflectometry(PMD)is a robust,noncoherent technique for the characterization of specular surface.For measuring high specular reflectivity surface,PMD can deliver micron radian range local gradient.However,when the measured surface has low specular reflectivity,the accuracy of the measured gradient is low since the captured fringe pattern shows low signal to noise ratio.The phase error characteristics in PMD system when testing low reflectivity surfaces are analyzed.The analysis illustrates that the random phase error increases rapidly while the nonlinear error drops slowly with the decreasing of the tested surface reflectivity.In order to attain high precision measurement of low reflectivity specular surface,a robust error reduction method based on wavelet de-noising is proposed to reduce the phase error.This error reduction method is compared with several other normally used methods in both simulation and experiment work.The method based on the wavelet de-noising shows better performance when measuring the low reflectivity specular surface.
基金The National Natural Science Foundation of China(No.51175267)the Natural Science Foundation of Jiangsu Province(No.BK2010481)+2 种基金the Ph.D.Programs Foundation of Ministry of Education of China(No.20113219120004)China Postdoctoral Science Foundation(No.20100481148)the Postdoctoral Science Foundation of Jiangsu Province(No.1001004B)
文摘To realize high-precision automatic measurement of two-dimensional geometric features on parts, a cooperative measurement system based on machine vision is constructed. Its hardware structure, functional composition and working principle are introduced. The mapping relationship between the feature image coordinates and the measuring space coordinates is established. The method of measuring path planning of small field of view (FOV) images is proposed. With the cooperation of the panoramic image of the object to be measured, the small FOV images with high object plane resolution are acquired automatically. Then, the auxiliary measuring characteristics are constructed and the parameters of the features to be measured are automatically extracted. Experimental results show that the absolute value of relative error is less than 0. 03% when applying the cooperative measurement system to gauge the hole distance of 100 mm nominal size. When the object plane resolving power of the small FOV images is 16 times that of the large FOV image, the measurement accuracy of small FOV images is improved by 14 times compared with the large FOV image. It is suitable for high-precision automatic measurement of two-dimensional complex geometric features distributed on large scale parts.
基金Supported by the National Natural Science Foundation of China(61301189)111 Project of China(B14010)
文摘A phase-derived velocity measurement method is proposed in a wideband coherent system,based on a precise echo model considering the inner pulse Doppler effect caused by fast moving targets.The Cramer-Rao low band of velocity measurement precision is deduced,demonstrating the high precision of the proposed method.Simulations and out-field experiments further validate the effectiveness of the proposed method in high-precision measurement and micro-motion extraction for targets with weak reflection intensity.Compared with the long-time integration approaches for velocity measurement,the phase-derived method is easy to implement and meets the requirement for high data rate,which makes it suitable for micro-motion feature extraction in wideband systems.
基金National Key Scientific Instrument and Equipment Development Project(No.2013YQ170539)
文摘Multi-sensor coordinate unification in dimensional metrology is used in order to get holistic, more accurate and reliable information about a workpiece based on several or multiple measurement values from one or more sensors. Because of the problem that standard ball is deficient as a standard artifact in the coordinate unification of high-precision composite measurement in two dimensions (2D) , a new method is proposed in this paper which uses angle gauge blocks as standard artifacts to achieve coordinate unification between the image sensor and the tactile probe. By comparing the standard ball with the angle gauge block as a standard artifact, theoretical analysis and experimental results are given to prove that it is more precise and more convenient to use angle gauge blocks as standard artifacts to achieve coordinate unification of high-precision composite measurement in two dimensions.
基金financially supported by the National Natural Science Foundation of China(No.52204084)the Open Research Fund of the State Key Laboratory of Coal Resources and safe Mining,CUMT,China(No.SKLCRSM 23KF004)+3 种基金the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities),China(No.FRF-IDRY-GD22-002)the Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange and Growth Program,China(No.QNXM20220009)the National Key R&D Program of China(Nos.2022YFC2905600 and 2022 YFC3004601)the Science,Technology&Innovation Project of Xiongan New Area,China(No.2023XAGG0061)。
文摘Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stress,the three-dimensional(3D)stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted,a newly defined characteristic parameter C_(ERP)was proposed as an indicator for evaluating the structural properties of rock masses,and a fuzzy relation matrix was established using the information distribution method.The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth.There is no remarkable correlation between the elastic modulus,Poisson's ratio and depth,and the distribution of data points is scattered and messy.Moreover,there is no obvious relationship between the rock quality designation(RQD)and depth.The maximum horizontal stress σ_(H) is a function of rock properties,showing a certain linear relationship with the C_(ERP)at the same depth.In addition,the overall change trend of σ_(H) determined by the established fuzzy identification method is to increase with the increase of C_(ERP).The fuzzy identification method also demonstrates a relatively detailed local relationship betweenσ_H and C_(ERP),and the predicted curve rises in a fluctuating way,which is in accord well with the measured stress data.
基金supported by the National Natural Science Foundation of China(Grant No.41974014)the Open Fund of State Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,Wuhan University(Grant No.19P01)
文摘It is significant for establishing gravity datum to construct precise gravity solid tidal model,A simple method with relatively low performance is to interpolate tidal parameters from the global gravity solid tide models.A competitive approach is to determine local gravity solid tidal model by harmonic analysis using long-time serial gravity observations.In this paper a new high-precision gravity solid tidal model for Precision Gravity Measurement Facility is estimated from two co-site gravimeters in the cave laboratory using modern international standard data processing techniques,whose accuracy is evaluated further by comparing with previous publications.The results show that:(1)the determined gravity solid tidal models from two co-site gravimeters are in good agreement with each other,of which the maximum differences for amplitude factors and phase delays don’t exceed 0.01700%and 2.50990°,respectively.(2)the performance of the obtained gravity solid tidal model is 0.00411 for amplitude factors and 0.24120°for phase delays,which is a little better than that of previous publications using superconducting gravity data from Wuhan station.(3)our results and methods are corrective and effective.(4)our model is tiny different from that provided by Wuhan station,which implies that it is necessary to construct a gravity solid tidal model for Precision Gravity Measurement Facility,rather than just adopting existing models at Wuhan station.Our results are helpful in realizing the goal of Precision Gravity Measurement Facility.
基金National Key Research and Development Plan Project(No.2020YFB2010800)National Natural Science Foundation of China(Nos.61905175,51775377,61971307)+4 种基金Fok Ying Tung Education Foundation(No.171055)China Postdoctoral Science Foundation(No.2020M680878)Guangdong Province Key Research and Development Plan Project(No.2020B0404030001)Tianjin Science and Technology Plan Project(No.20YDTPJC01660)Project of Foreign Affairs Committee of China Aviation Development Sichuan Gas Turbine Research Institute(Nos.GJCZ-2020-0040,GJCZ-2020-0041)。
文摘In order to achieve high precision measurement of inductance in a wide frequency range,a method of inductance measurement based on double-excitation auto-balancing bridge is proposed.In this method,the direct digital synthesizer(DDS)as signal generator is used as the bridge excitation source,and the bridge is automatically balanced by adjusting and measuring the voltage ratio.Using standard resistors,the system can achieve high precision measurement of four-terminal pair inductors in the frequency range of 100Hz-100kHz.Aiming at the low efficiency of bridge balancing,an iterative balancing algorithm based on the steepest descent method is proposed.In order to suppress the interference caused by the initial phase change and non-integer periodic sampling,the high-precision measurement of the complex impedance of inductance is realized based on the all-phase fast Fourier transform(apFFT).Finally,the corresponding measurement system is built and the inductance measurement experiment is carried out.The experimental results show that the relative error of the system for inductance measurement can be as low as 0.009%,and the optimal relative measurement uncertainty of the system can reach 9.89×10^(-4)compared with 5×10^(-5)of commercial impedance analyzer.
基金funded by National Key Research and Development Project(Grant No.2022YFC2204301)the Special Fund of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant No.CEAIEF2022030105).
文摘From 2019 to 2021,China Seismic Experimental Site has built twelve 300 m deep well multi-measurement comprehensive observation stations in the cross-fault area of the Aninghe-Zemuhe fault zone,integrating BBVS120 very broadband borehole seismometer,RZB four-gauge borehole strainmeter and geothermometer with resolution up to 0.0001℃.The borehole diameter is 150 mm and the inner diameter of the sleeve is 130 mm.The multi-item integrated observation system is divided into two parts:underground and surface.The downhole part is mainly composed of sensor and power supply signal isolation.
文摘In order to accurately measure an object’s three-dimensional surface shape,the influence of sampling on it was studied.First,on the basis of deriving spectra expressions through the Fourier transform,the generation of CCD pixels was analyzed,and its expression was given.Then,based on the discrete expression of deformation fringes obtained after sampling,its Fourier spectrum expression was derived,resulting in an infinitely repeated"spectra island"in the frequency domain.Finally,on the basis of using a low-pass filter to remove high-order harmonic components and retaining only one fundamental frequency component,the inverse Fourier transform was used to reconstruct the signal strength.A method of reducing the sampling interval,i.e.,reducing the number of sampling points per fringe,was proposed to increase the ratio between the sampling frequency and the fundamental frequency of the grating.This was done to reconstruct the object’s surface shape more accurately under the condition of m>4.The basic principle was verified through simulation and experiment.In the simulation,the sampling intervals were 8 pixels,4 pixels,2 pixels,and 1 pixel,the maximum absolute error values obtained in the last three situations were 88.80%,38.38%,and 31.50%in the first situation,respectively,and the corresponding average absolute error values are 71.84%,43.27%,and 32.26%.It is demonstrated that the smaller the sampling interval,the better the recovery effect.Taking the same four sampling intervals in the experiment as in the simulation can also lead to the same conclusions.The simulated and experimental results show that reducing the sampling interval can improve the accuracy of object surface shape measurement and achieve better reconstruction results.
基金supported by the National Key R&D Program(No.2022YFA1602201)。
文摘This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch signal to obtain bunch-by-bunch and turn-by-turn longitudinal parameters,such as bunch length and synchronous phase.The bunch signal is obtained using a button electrode with a bandwidth of several gigahertz.The data acquisition device was a high-speed digital oscilloscope with a sampling rate of more than 10 GS/s,and the single-shot sampling data buffer covered thousands of turns.The bunch-length and synchronous phase information were extracted via offline calculations using Python scripts.The calibration coefficient of the system was determined using a commercial streak camera.Moreover,this technique was tested on two different storage rings and successfully captured various longitudinal transient processes during the harmonic cavity debugging process at the Shanghai Synchrotron Radiation Facility(SSRF),and longitudinal instabilities were observed during the single-bunch accumulation process at Hefei Light Source(HLS).For Gaussian-distribution bunches,the uncertainty of the bunch phase obtained using this technique was better than 0.2 ps,and the bunch-length uncertainty was better than 1 ps.The dynamic range exceeded 10 ms.This technology is a powerful and versatile beam diagnostic tool that can be conveniently deployed in high-energy electron storage rings.
基金Supported By Open Fund of Hubei Key Laboratory of Oil and Gas Drilling and Production Engineering(Yangtze University),YQZC202309.
文摘A new measurement device,consisting of swirling blades and capsule-shaped throttling elements,is proposed in this study to eliminate typical measurement errors caused by complex flow patterns in gas-liquid flow.The swirling blades are used to transform the complex flow pattern into a forced annular flow.Drawing on the research of existing blockage flow meters and also exploiting the single-phase flow measurement theory,a formula is introduced to measure the phase-separated flow of gas and liquid.The formula requires the pressure ratio,Lockhart-Martinelli number(L-M number),and the gas phase Froude number.The unknown parameters appearing in the formula are fitted through numerical simulation using computational fluid dynamics(CFD),which involves a comprehensive analysis of the flow field inside the device from multiple perspectives,and takes into account the influence of pressure fluctuations.Finally,the measurement model is validated through an experimental error analysis.The results demonstrate that the measurement error can be maintained within±8%for various flow patterns,including stratified flow,bubble flow,and wave flow.
基金This project is partly funded by Science and Technology Project of State Grid Zhejiang Electric Power Co.,Ltd.“Research on active Security Defense Strategies for Distribution Internet of Things Based on Trustworthy,under Grant No.5211DS22000G”.
文摘The application of Intelligent Internet of Things(IIoT)in constructing distribution station areas strongly supports platform transformation,upgrade,and intelligent integration.The sensing layer of IIoT comprises the edge convergence layer and the end sensing layer,with the former using intelligent fusion terminals for real-time data collection and processing.However,the influx of multiple low-voltage in the smart grid raises higher demands for the performance,energy efficiency,and response speed of the substation fusion terminals.Simultaneously,it brings significant security risks to the entire distribution substation,posing a major challenge to the smart grid.In response to these challenges,a proposed dynamic and energy-efficient trust measurement scheme for smart grids aims to address these issues.The scheme begins by establishing a hierarchical trust measurement model,elucidating the trust relationships among smart IoT terminals.It then incorporates multidimensional measurement factors,encompassing static environmental factors,dynamic behaviors,and energy states.This comprehensive approach reduces the impact of subjective factors on trust measurements.Additionally,the scheme incorporates a detection process designed for identifying malicious low-voltage end sensing units,ensuring the prompt identification and elimination of any malicious terminals.This,in turn,enhances the security and reliability of the smart grid environment.The effectiveness of the proposed scheme in pinpointing malicious nodes has been demonstrated through simulation experiments.Notably,the scheme outperforms established trust metric models in terms of energy efficiency,showcasing its significant contribution to the field.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 92065113, 11904357, 62075208, and 12174367)the Innovation Programme for Quantum Science and Technology (Grant No. 2021ZD0301604)+1 种基金the National Key Research and Development Program of China (Grant No. 2021YFE0113100)supported by Beijing Academy of Quantum Information Sciences
文摘Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection.
基金supported by the National Key Research and Development Project (No.2018YFE0126400)Key Program of Marine Economy Development (Six Marine Industries)Special Foundation of Department of Natural Resources of Guangdong Province (GDNRC[2020]047)。
文摘It remains a great challenge to understand the hydrates involved in phenomena in practical oil and gas systems.The adhesion forces between hydrate particles,between hydrate particles and pipe walls,and between hydrate particles and reservoir particles are essential factors that control the behaviors of clathrate hydrates in different applications.In this review,we summarize the typical micro-force measurement apparatus and methods utilized to study hydrate particle systems.In addition,the adhesion test results,the related understandings,and the applied numerical calculation models are systematically discussed.
基金supported by Beijing Insititute of Technology Research Fund Program for Young Scholars(2020X04104)。
文摘In this paper,an improved spatio-temporal alignment measurement method is presented to address the inertial matching measurement of hull deformation under the coexistence of time delay and large misalignment angle.Large misalignment angle and time delay often occur simultaneously and bring great challenges to the accurate measurement of hull deformation in space and time.The proposed method utilizes coarse alignment with large misalignment angle and time delay estimation of inertial measurement unit modeling to establish a brand-new spatiotemporal aligned hull deformation measurement model.In addition,two-step loop control is designed to ensure the accurate description of dynamic deformation angle and static deformation angle by the time-space alignment method of hull deformation.The experiments illustrate that the proposed method can effectively measure the hull deformation angle when time delay and large misalignment angle coexist.
基金funded through the Researchers Supporting Project Number(RSPD2024R596),King Saud University,Riyadh,Saudi Arabia.
文摘The measurement and mapping of objects in the outer environment have traditionally been conducted using ground-based monitoring systems,as well as satellites.More recently,unmanned aerial vehicles have also been employed for this purpose.The accurate detection and mapping of a target such as buildings,trees,and terrains are of utmost importance in various applications of unmanned aerial vehicles(UAVs),including search and rescue operations,object transportation,object detection,inspection tasks,and mapping activities.However,the rapid measurement and mapping of the object are not currently achievable due to factors such as the object’s size,the intricate nature of the sites,and the complexity of mapping algorithms.The present system introduces a costeffective solution for measurement and mapping by utilizing a small unmanned aerial vehicle(UAV)equipped with an 8-beam Light Detection and Ranging(LiDAR)system.This approach offers advantages over traditional methods that rely on expensive cameras and complex algorithm-based approaches.The reflective properties of laser beams have also been investigated.The system provides prompt results in comparison to traditional camerabased surveillance,with minimal latency and the need for complex algorithms.The Kalman estimation method demonstrates improved performance in the presence of noise.The measurement and mapping of external objects have been successfully conducted at varying distances,utilizing different resolutions.
基金funded by Hebei Key Laboratory of Seismic Disaster Instrument and Monitoring Technology(Grant No.FZ224201)National Key Research and Development Project(Grant No.2022YFC2204301)the Special Fund of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant No.CEAIEF2022030105).
文摘The vibration interference of the reference corner cube runs through the free flight process of the free-falling corner cube,which is superimposed on the whole laser interference fringes.Thus,it is necessary to solve the interference fringes with the entire fringe to analyze the quantitative influence of vibration on gravity measurements.
文摘This study aims to improve the accuracy and safety of steel plate thickness calibration.A differential noncontact thickness measurement calibration system based on laser displacement sensors was designed to address the problems of low precision of traditional contact thickness gauges and radiation risks of radiation-based thickness gauges.First,the measurement method and measurement structure of the thickness calibration system were introduced.Then,the hardware circuit of the thickness system was established based on the STM32 core chip.Finally,the system software was designed to implement system control to filter algorithms and human-computer interaction.Experiments have proven the excellent performance of the differential noncontact thickness measurement calibration system based on laser displacement sensors,which not only considerably improves measurement accuracy but also effectively reduces safety risks during the measurement process.The system offers guiding significance and application value in the field of steel plate production and processing.
基金This work is supported by National Natural Science Foundation of China(Nos.U23B20151 and 52171253).
文摘Owing to the complex lithology of unconventional reservoirs,field interpreters usually need to provide a basis for interpretation using logging simulation models.Among the various detection tools that use nuclear sources,the detector response can reflect various types of information of the medium.The Monte Carlo method is one of the primary methods used to obtain nuclear detection responses in complex environments.However,this requires a computational process with extensive random sampling,consumes considerable resources,and does not provide real-time response results.Therefore,a novel fast forward computational method(FFCM)for nuclear measurement that uses volumetric detection constraints to rapidly calculate the detector response in various complex environments is proposed.First,the data library required for the FFCM is built by collecting the detection volume,detector counts,and flux sensitivity functions through a Monte Carlo simulation.Then,based on perturbation theory and the Rytov approximation,a model for the detector response is derived using the flux sensitivity function method and a one-group diffusion model.The environmental perturbation is constrained to optimize the model according to the tool structure and the impact of the formation and borehole within the effective detection volume.Finally,the method is applied to a neutron porosity tool for verification.In various complex simulation environments,the maximum relative error between the calculated porosity results of Monte Carlo and FFCM was 6.80%,with a rootmean-square error of 0.62 p.u.In field well applications,the formation porosity model obtained using FFCM was in good agreement with the model obtained by interpreters,which demonstrates the validity and accuracy of the proposed method.