To overcome the shortcomings of the traditional passive ranging technology based on image, such as poor ranging accuracy, low reliability and complex system, a new visual passive ranging method based on re-entrant coa...To overcome the shortcomings of the traditional passive ranging technology based on image, such as poor ranging accuracy, low reliability and complex system, a new visual passive ranging method based on re-entrant coaxial optical path is presented. The target image is obtained using double cameras with coaxial optical path. Since there is imaging optical path difference between the cameras, the images are different. In comparison of the image differences, the target range could be reversed. The principle of the ranging method and the ranging model are described. The relationship among parameters in the ranging process is analyzed quantitatively. Meanwhile,the system composition and technical realization scheme are also presented. Also, the principle of the method is verified by the equivalent experiment. The experimental results show that the design scheme is correct and feasible with good robustness. Generally, the ranging error is less than 10% with good convergence. The optical path is designed in a re-entrant mode to reduce the volume and weight of the system. Through the coaxial design,the visual passive range of the targets with any posture can be obtained in real time. The system can be widely used in electro-optical countermeasure and concealed photoelectric detection.展开更多
Conventional frequency-sweep interferometry is unreliable for noncooperative or long-distance targets owing to scattering on the target surface.Hence,this paper proposes a laser frequency-swept carrier(LFSC)ranging me...Conventional frequency-sweep interferometry is unreliable for noncooperative or long-distance targets owing to scattering on the target surface.Hence,this paper proposes a laser frequency-swept carrier(LFSC)ranging method based on resonant cavity enhancement for long-distance noncooperative target measurements and weak-signal detection.Experimental verification revealed that for a target comprising an oxidized black aluminum plate at a distance of 16 m,the standard deviation of 10 measurements was less than 70μm,measurement accuracy exceeded 27μm,and system ranging resolution exceeded 0.13 mm when the target feedback light was very weak.This method is useful for measurements of noncooperative targets,eg.,large-scale component assembly,industrial measurement,and biomedical testing.展开更多
The complex Red River fault zone(RRFZ),which is situated in the southwestern region of China and separates the Indochina plate and South China blocks,has diverse seismic activities in different segments.To reveal the ...The complex Red River fault zone(RRFZ),which is situated in the southwestern region of China and separates the Indochina plate and South China blocks,has diverse seismic activities in different segments.To reveal the detailed geometric characteristics of the RRFZ at different sections and to better understand the seismogenic environment,in 2022 and 2023 we deployed 7 seismic dense linear arrays,consisting of 574 nodal stations,across the RRFZ in the northern and southern segments near the towns Midu,Gasa,Zhega,Dazhai,Xinzhai,and Taoyuan.The linear arrays,which extend from 2.4 to 12.5 km in length with station intervals ranging between 40 and140 m,recorded seismic ambient noise for approximately one month.Using the extended range phase shift method,we extract the phase velocity dispersion curves of the Rayleigh waves between 0.9 and 10 Hz,which are then used to invert for the high resolution shearwave velocity structures across the RRFZ beneath the linear arrays.The key findings are:(1)the 7 imaged sections of the RRFZ exhibit quite similar structures,with higher velocities on the SW side and lower velocities on the NE side;the velocity variation is consistent with the surface geological structures along the RRFZ;(2)the shear-wave velocities on the SW side of the RRFZ at the northern Midu section and southern Gasa-Dazhai sections are generally higher than their counterparts in the southern Xinzhai-Taoyuan sections,which reflects lithological variations from the marble-dominated Paleoproterozoic Along basement to the gneiss dominated Paleoproterozoic Qingshuihe basement;(3)from the northern Midu section to the southern region where the RRFZ intersects with the Xiaojiang Fault,the major faults of the RRFZ exhibit a consistent high-angle,NE-dipping structure;(4)the low shear-wave velocities immediately to the NE of the velocity boundary may indicate a faulted zone due to long-term shearing,where excessive amplifications of ground motions could occur.This study provides new insights into the characteristics of the shallow structures of the RRFZ.展开更多
Ranging is indispensable in a variety of fields,encompassing basic science,manufacturing,production,and daily life.Although traditional methods based on the dispersive interferometry(DPI)in the frequency domain provid...Ranging is indispensable in a variety of fields,encompassing basic science,manufacturing,production,and daily life.Although traditional methods based on the dispersive interferometry(DPI)in the frequency domain provide high precision,their measurement speed is slow,preventing the capture and measurement of dynamic displacements.Here,we propose a fast and precise ranging method based on the dispersion-controlled dual-swept laser(DCDSL),which allows the dynamical displacement measurement of the target under test.Due to the slight frequency sweeping speed difference between the signal and reference lights,there is a zero-frequency point of the oscillation(ZPO)generated in the interference signal,whose position in the time domain is linearly related to the relative delay between the signal and reference lights.Utilizing phase demodulation of the interference signal from the DCDSL and the fitting algorithm,the time-domain position of ZPO is accurately found,which precisely maps to the displacement of the target in real time without direction ambiguity.The fast frequency sweeping rate ensures fast ranging with the MHz order refresh frame.We have experimentally demonstrated its capabilities for precise measurement of static distances and the capture of dynamic displacement processes through simulations and experiments,with the measurement range encompassing the entire interference period(56 mm).Compared to a calibrated motorized displacement platform,the residual error for full-range distance measurements is within 10μm,and the error in average speed during dynamic processes is 0.46%.Additionally,the system exhibits excellent stability,achieving a minimum Allan deviation of 4.25 nm over an average duration of approximately 4 ms.This method ensures high precision while maintaining a simple system,thereby advancing the practical implementation of ultrafast length metrology.展开更多
The study of wave guide invariant in underwater acoustics is one of attracted topics in recent 30 years. The interferences of direct wave and reflect wave from sea surface and sea bottom of underwater target radiated ...The study of wave guide invariant in underwater acoustics is one of attracted topics in recent 30 years. The interferences of direct wave and reflect wave from sea surface and sea bottom of underwater target radiated noise inherent the information of target distance. Extraction of these distance information will provide a possible new way in passive ranging for underwater target. The theoretical analysis and the results of at sea experiments show that the LOFAR （Low Frequency Analysis Record） figure inherently contains the range and moving information of passive acoustic sources, even in the situation that the receiver is only one single hydrophone. The theoretical analysis of extraction of target distance information by using wave guide invariant is presented in this paper. It is shown that, based on the interference striation pattern of target, the hydrophone array system is possible to extract the distance information with quite high array gain. Although the mathematical constrain conditions in forming interference striation pattern are different for individual array element, but it is proved that the differences of time delays between array elements can be used in compensation of beamforming. The theoretical analysis, system simulation and some results of at sea experiment show a new way in passive ranging and target recognition.展开更多
The approach to estimate the length of extended targets by using the bistatic high resolution range profile（ H RRP） is analyzed in this paper. The relationship between the bistatic H RRP and the monostatic H RRP of ...The approach to estimate the length of extended targets by using the bistatic high resolution range profile（ H RRP） is analyzed in this paper. The relationship between the bistatic H RRP and the monostatic H RRP of extended targets are investigated. It is demonstrated by simulations that the target length measured by the bistatic H RRP is more meaningful and accurate than that by the monostatic HRRP,though the monostatic H RRP has been well developed and widely used in target recognizing and classification. The estimation results of a cone shaped target are present and compared at the end of the paper. To assure the reliability of the simulation,the bistatic H RRP is obtained through the scattering field data calculated by a fullwave numerical method,FE-BI-MLFMA.展开更多
Diabetes has become a concern in the developed and developing countries with its growing number of patients reported to the ministry of health records. This paper discusses the use of the Autoregressive Fractional Mov...Diabetes has become a concern in the developed and developing countries with its growing number of patients reported to the ministry of health records. This paper discusses the use of the Autoregressive Fractional Moving Average (ARFIMA) technique to modeling the diabetes patient’s attendance at Al-Baha hospitals using monthly time series data. The data used in the analysis of this paper are monthly readings of diabetes patients data covered the period January 2006-December 2016. The data were collected from the General Directorate of Health Affairs, Al-Baha region. The autoregressive fractional moving average approach was applied to the data through the model identification, estimation, diagnostic checking and forecasting. Hurst test results and ACF confirmed that there is a long memory behavior in diabetic patient’s data. Also, the fractional difference to diabetes series data revealed that (<em>d</em> = 0.44). Moreover, unit root tests indicated that the fractional difference of diabetes series level is stationary. Furthermore, according to AIC and BIC of model selection criteria ARFIMA (1, 0.44, 0) model shown the smallest values, hence this model was chosen as an adequate represents the data. Also, a diagnostic check confirmed that ARFIMA was appropriate and highly recommended in modeling and forecasting this type of data.展开更多
The effect of diffraction on the ultrasonic velocity measured by the pulse interference method has been investigated in VHF range theoretically and experimentally. Two silicate glasses are taken as the specimens, thei...The effect of diffraction on the ultrasonic velocity measured by the pulse interference method has been investigated in VHF range theoretically and experimentally. Two silicate glasses are taken as the specimens, their frequency dependences of longitudinal velocities are measured in the frequency range of 50-350 MHz, and the phase advances of ultrasonic signals caused by diffraction effect are calculated using A. O. Williams' theoretical expression. For the velocity error due to diffraction effect, the experimental results are in good agreement with the theoretical prediction. It has been shown that the velocity error due to diffraction effect is directly proportional to dθ21 (f)/df, whereθ21 (f) is the phase advances difference between the two partial reflection signals used in velocity measurement and f is the ultrasonic frequency.展开更多
Determination of the energy range is an important precondition of focus calibration using alignment procedure （FOCAL） test. A new method to determine the energy range of FOCAL off-lined is presented in this paper. I...Determination of the energy range is an important precondition of focus calibration using alignment procedure （FOCAL） test. A new method to determine the energy range of FOCAL off-lined is presented in this paper. Independent of the lithographic tool, the method is time-saving and effective. The influences of some process factors, e.g. resist thickness, post exposure bake （PEB） temperature, PEB time and development time, on the energy range of FOCAL are analyzed.展开更多
By inserting an air cavity into a one-dimensional photonic crystal of LiF/GaSb, a tunable filter covering the whole visible range is proposed. Following consideration of the dispersion of the materials, through modula...By inserting an air cavity into a one-dimensional photonic crystal of LiF/GaSb, a tunable filter covering the whole visible range is proposed. Following consideration of the dispersion of the materials, through modulating the thickness of the air cavity, we demonstrate that a single resonant peak can shift from 416.1 to 667.3 nm in the band gap at normal incidence by means of the transfer matrix method. The research also shows that the transmittance of the channel can be maximized when the number of periodic Li F/Ga Sb layers on one side of the air defect layer is equal to that of the other side. When adding a period to both sides respectively, the full width at half maximum of the defect mode is reduced by one order of magnitude. This structure will provide a promising approach to fabricate practical tunable filters in the visible region with ultra-wide tuning range.展开更多
We explored the insinuations of bio-convection and thermal radiation on nanofluid transportation across stretching permeable wedge with magnetic force.Appropriate similarity transformation variables are utilized to ac...We explored the insinuations of bio-convection and thermal radiation on nanofluid transportation across stretching permeable wedge with magnetic force.Appropriate similarity transformation variables are utilized to achieve ordinary differential equations.In order to tackle the non-linearity of these equations,numerical procedure based on shooting technique and Range Kutta method are harnessed on MATLAB platform.Computational and devour is carried out to evaluate the influence of controlling limitations on temperature,velocity,concentration of nanofluids and micro-organisms density.The growing strength of thermophoresis and Brownian motion enhance the fluid temperature.The profile volume fraction show decline against higher values of parameters which are Lewis number,unsteadiness and Brownian motion but opposite trend noted against higher value of Williamson and thermophoresis parameters.The skin friction values rise with the growing values of parameter of wedge angle for the moving wedge.The motile organism profile exhibits decrease against growing strength of Peclet number,bioconvection Lewis number,temperature difference and unsteady parameters while opposite behavior has been noted against wedge angle parameter.展开更多
This study aims to measure how well China's green,low-carbon,and circulardevelopment economic system(theGLCCD Economic System)is being developed.By establishing the indicator system and indicators,the spatiotempor...This study aims to measure how well China's green,low-carbon,and circulardevelopment economic system(theGLCCD Economic System)is being developed.By establishing the indicator system and indicators,the spatiotemporal range entropy weight method,Gini coefficient,Theil index,convergence model,and national and provincial data from 2012 to 2017 are employed.The construction level of almost all GLCCD Economic Systems at national and provincial levels has shown improvement during the study period.Among them,a significant boost is only observed in the development power indicator;improvement in the production system indicator and development benefit indicatorismild,andthelifesystemindicator sees a decline year by year.The construction level of the GLCCD Economic System throughout China is generally balanced but tends to expand in scale.However,the inter-regional developmenttbenefit indicator showsaconvergence trend.Based on the analysis of the similarities and differences between greenandlow-carboncircular development,the development power and development benefit,production system,and life system are incorporated into a unified logical framework.The construction level of the GLCCD Economic System is measured as a whole in a holistic manner.This study finds out the scientific connotation oftheGLCCD Economic System.The changing trends and regional differences in the construction level of the GLCCD Economic System are revealed.These findings provide a clear and reliable decision-making basis for the construction of the GLCCD Economic System.展开更多
基金Supported by the National Basic Research Program of China under Grant No 2014CB340102
文摘To overcome the shortcomings of the traditional passive ranging technology based on image, such as poor ranging accuracy, low reliability and complex system, a new visual passive ranging method based on re-entrant coaxial optical path is presented. The target image is obtained using double cameras with coaxial optical path. Since there is imaging optical path difference between the cameras, the images are different. In comparison of the image differences, the target range could be reversed. The principle of the ranging method and the ranging model are described. The relationship among parameters in the ranging process is analyzed quantitatively. Meanwhile,the system composition and technical realization scheme are also presented. Also, the principle of the method is verified by the equivalent experiment. The experimental results show that the design scheme is correct and feasible with good robustness. Generally, the ranging error is less than 10% with good convergence. The optical path is designed in a re-entrant mode to reduce the volume and weight of the system. Through the coaxial design,the visual passive range of the targets with any posture can be obtained in real time. The system can be widely used in electro-optical countermeasure and concealed photoelectric detection.
基金National Natural Science Foundation of China(52475532, 51875447)
文摘Conventional frequency-sweep interferometry is unreliable for noncooperative or long-distance targets owing to scattering on the target surface.Hence,this paper proposes a laser frequency-swept carrier(LFSC)ranging method based on resonant cavity enhancement for long-distance noncooperative target measurements and weak-signal detection.Experimental verification revealed that for a target comprising an oxidized black aluminum plate at a distance of 16 m,the standard deviation of 10 measurements was less than 70μm,measurement accuracy exceeded 27μm,and system ranging resolution exceeded 0.13 mm when the target feedback light was very weak.This method is useful for measurements of noncooperative targets,eg.,large-scale component assembly,industrial measurement,and biomedical testing.
基金funded by the National Key Research and Development Project of China(Grant No.2021YFC3000600)the China Earthquake Science Experiment Field-Cross-fault Observation Array-Red River Fault Scientific Drilling Project Geophysical Prospecting Site Selection Project+2 种基金Anhui Province Science and Technology Breakthrough Plan Project(Key Project,202423l10050030)the Earthquake Science and Technology Spark Program of the China Earthquake Administration(XH23020YA)the Anhui Mengcheng National Geophysical Observatory Joint Open Fund(MENGO-202307)。
文摘The complex Red River fault zone(RRFZ),which is situated in the southwestern region of China and separates the Indochina plate and South China blocks,has diverse seismic activities in different segments.To reveal the detailed geometric characteristics of the RRFZ at different sections and to better understand the seismogenic environment,in 2022 and 2023 we deployed 7 seismic dense linear arrays,consisting of 574 nodal stations,across the RRFZ in the northern and southern segments near the towns Midu,Gasa,Zhega,Dazhai,Xinzhai,and Taoyuan.The linear arrays,which extend from 2.4 to 12.5 km in length with station intervals ranging between 40 and140 m,recorded seismic ambient noise for approximately one month.Using the extended range phase shift method,we extract the phase velocity dispersion curves of the Rayleigh waves between 0.9 and 10 Hz,which are then used to invert for the high resolution shearwave velocity structures across the RRFZ beneath the linear arrays.The key findings are:(1)the 7 imaged sections of the RRFZ exhibit quite similar structures,with higher velocities on the SW side and lower velocities on the NE side;the velocity variation is consistent with the surface geological structures along the RRFZ;(2)the shear-wave velocities on the SW side of the RRFZ at the northern Midu section and southern Gasa-Dazhai sections are generally higher than their counterparts in the southern Xinzhai-Taoyuan sections,which reflects lithological variations from the marble-dominated Paleoproterozoic Along basement to the gneiss dominated Paleoproterozoic Qingshuihe basement;(3)from the northern Midu section to the southern region where the RRFZ intersects with the Xiaojiang Fault,the major faults of the RRFZ exhibit a consistent high-angle,NE-dipping structure;(4)the low shear-wave velocities immediately to the NE of the velocity boundary may indicate a faulted zone due to long-term shearing,where excessive amplifications of ground motions could occur.This study provides new insights into the characteristics of the shallow structures of the RRFZ.
基金Graduate Research and Innovation Foundation of Chongqing(CYB240013)Graduate Funding Program in the College of Optoelectronic Engineering(Chongqing University)(GDYKC202409)+1 种基金National Natural Science Foundation for Distinguished Young Scholars(61825501)Chongqing Natural Science Foundation of Innovative Research Groups(cstc2020jcyj,cxttX0005)。
文摘Ranging is indispensable in a variety of fields,encompassing basic science,manufacturing,production,and daily life.Although traditional methods based on the dispersive interferometry(DPI)in the frequency domain provide high precision,their measurement speed is slow,preventing the capture and measurement of dynamic displacements.Here,we propose a fast and precise ranging method based on the dispersion-controlled dual-swept laser(DCDSL),which allows the dynamical displacement measurement of the target under test.Due to the slight frequency sweeping speed difference between the signal and reference lights,there is a zero-frequency point of the oscillation(ZPO)generated in the interference signal,whose position in the time domain is linearly related to the relative delay between the signal and reference lights.Utilizing phase demodulation of the interference signal from the DCDSL and the fitting algorithm,the time-domain position of ZPO is accurately found,which precisely maps to the displacement of the target in real time without direction ambiguity.The fast frequency sweeping rate ensures fast ranging with the MHz order refresh frame.We have experimentally demonstrated its capabilities for precise measurement of static distances and the capture of dynamic displacement processes through simulations and experiments,with the measurement range encompassing the entire interference period(56 mm).Compared to a calibrated motorized displacement platform,the residual error for full-range distance measurements is within 10μm,and the error in average speed during dynamic processes is 0.46%.Additionally,the system exhibits excellent stability,achieving a minimum Allan deviation of 4.25 nm over an average duration of approximately 4 ms.This method ensures high precision while maintaining a simple system,thereby advancing the practical implementation of ultrafast length metrology.
文摘The study of wave guide invariant in underwater acoustics is one of attracted topics in recent 30 years. The interferences of direct wave and reflect wave from sea surface and sea bottom of underwater target radiated noise inherent the information of target distance. Extraction of these distance information will provide a possible new way in passive ranging for underwater target. The theoretical analysis and the results of at sea experiments show that the LOFAR （Low Frequency Analysis Record） figure inherently contains the range and moving information of passive acoustic sources, even in the situation that the receiver is only one single hydrophone. The theoretical analysis of extraction of target distance information by using wave guide invariant is presented in this paper. It is shown that, based on the interference striation pattern of target, the hydrophone array system is possible to extract the distance information with quite high array gain. Although the mathematical constrain conditions in forming interference striation pattern are different for individual array element, but it is proved that the differences of time delays between array elements can be used in compensation of beamforming. The theoretical analysis, system simulation and some results of at sea experiment show a new way in passive ranging and target recognition.
基金Supported by the National Natural Science Fundation of China(61001192)
文摘The approach to estimate the length of extended targets by using the bistatic high resolution range profile（ H RRP） is analyzed in this paper. The relationship between the bistatic H RRP and the monostatic H RRP of extended targets are investigated. It is demonstrated by simulations that the target length measured by the bistatic H RRP is more meaningful and accurate than that by the monostatic HRRP,though the monostatic H RRP has been well developed and widely used in target recognizing and classification. The estimation results of a cone shaped target are present and compared at the end of the paper. To assure the reliability of the simulation,the bistatic H RRP is obtained through the scattering field data calculated by a fullwave numerical method,FE-BI-MLFMA.
文摘Diabetes has become a concern in the developed and developing countries with its growing number of patients reported to the ministry of health records. This paper discusses the use of the Autoregressive Fractional Moving Average (ARFIMA) technique to modeling the diabetes patient’s attendance at Al-Baha hospitals using monthly time series data. The data used in the analysis of this paper are monthly readings of diabetes patients data covered the period January 2006-December 2016. The data were collected from the General Directorate of Health Affairs, Al-Baha region. The autoregressive fractional moving average approach was applied to the data through the model identification, estimation, diagnostic checking and forecasting. Hurst test results and ACF confirmed that there is a long memory behavior in diabetic patient’s data. Also, the fractional difference to diabetes series data revealed that (<em>d</em> = 0.44). Moreover, unit root tests indicated that the fractional difference of diabetes series level is stationary. Furthermore, according to AIC and BIC of model selection criteria ARFIMA (1, 0.44, 0) model shown the smallest values, hence this model was chosen as an adequate represents the data. Also, a diagnostic check confirmed that ARFIMA was appropriate and highly recommended in modeling and forecasting this type of data.
文摘The effect of diffraction on the ultrasonic velocity measured by the pulse interference method has been investigated in VHF range theoretically and experimentally. Two silicate glasses are taken as the specimens, their frequency dependences of longitudinal velocities are measured in the frequency range of 50-350 MHz, and the phase advances of ultrasonic signals caused by diffraction effect are calculated using A. O. Williams' theoretical expression. For the velocity error due to diffraction effect, the experimental results are in good agreement with the theoretical prediction. It has been shown that the velocity error due to diffraction effect is directly proportional to dθ21 (f)/df, whereθ21 (f) is the phase advances difference between the two partial reflection signals used in velocity measurement and f is the ultrasonic frequency.
文摘Determination of the energy range is an important precondition of focus calibration using alignment procedure （FOCAL） test. A new method to determine the energy range of FOCAL off-lined is presented in this paper. Independent of the lithographic tool, the method is time-saving and effective. The influences of some process factors, e.g. resist thickness, post exposure bake （PEB） temperature, PEB time and development time, on the energy range of FOCAL are analyzed.
基金Project supported by the National Natural Science Foundation of China(Nos.61575138,61307069,51205273)the Top Young Academic Leaders and the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi
文摘By inserting an air cavity into a one-dimensional photonic crystal of LiF/GaSb, a tunable filter covering the whole visible range is proposed. Following consideration of the dispersion of the materials, through modulating the thickness of the air cavity, we demonstrate that a single resonant peak can shift from 416.1 to 667.3 nm in the band gap at normal incidence by means of the transfer matrix method. The research also shows that the transmittance of the channel can be maximized when the number of periodic Li F/Ga Sb layers on one side of the air defect layer is equal to that of the other side. When adding a period to both sides respectively, the full width at half maximum of the defect mode is reduced by one order of magnitude. This structure will provide a promising approach to fabricate practical tunable filters in the visible region with ultra-wide tuning range.
基金This work was supported by the National Natural Science Foundation of China(No.52106004)for which the authors are thankful.
文摘We explored the insinuations of bio-convection and thermal radiation on nanofluid transportation across stretching permeable wedge with magnetic force.Appropriate similarity transformation variables are utilized to achieve ordinary differential equations.In order to tackle the non-linearity of these equations,numerical procedure based on shooting technique and Range Kutta method are harnessed on MATLAB platform.Computational and devour is carried out to evaluate the influence of controlling limitations on temperature,velocity,concentration of nanofluids and micro-organisms density.The growing strength of thermophoresis and Brownian motion enhance the fluid temperature.The profile volume fraction show decline against higher values of parameters which are Lewis number,unsteadiness and Brownian motion but opposite trend noted against higher value of Williamson and thermophoresis parameters.The skin friction values rise with the growing values of parameter of wedge angle for the moving wedge.The motile organism profile exhibits decrease against growing strength of Peclet number,bioconvection Lewis number,temperature difference and unsteady parameters while opposite behavior has been noted against wedge angle parameter.
基金This paper is a phased research result of the National Natural Science Foundation of China(No.71873143)the key discipline construction program of the Summit Plan of the ChineseAcademyof Social Sciences.
文摘This study aims to measure how well China's green,low-carbon,and circulardevelopment economic system(theGLCCD Economic System)is being developed.By establishing the indicator system and indicators,the spatiotemporal range entropy weight method,Gini coefficient,Theil index,convergence model,and national and provincial data from 2012 to 2017 are employed.The construction level of almost all GLCCD Economic Systems at national and provincial levels has shown improvement during the study period.Among them,a significant boost is only observed in the development power indicator;improvement in the production system indicator and development benefit indicatorismild,andthelifesystemindicator sees a decline year by year.The construction level of the GLCCD Economic System throughout China is generally balanced but tends to expand in scale.However,the inter-regional developmenttbenefit indicator showsaconvergence trend.Based on the analysis of the similarities and differences between greenandlow-carboncircular development,the development power and development benefit,production system,and life system are incorporated into a unified logical framework.The construction level of the GLCCD Economic System is measured as a whole in a holistic manner.This study finds out the scientific connotation oftheGLCCD Economic System.The changing trends and regional differences in the construction level of the GLCCD Economic System are revealed.These findings provide a clear and reliable decision-making basis for the construction of the GLCCD Economic System.
