The internal energy distribution of waves can be described using ocean-wave spectra.In many ways,obtaining wave spectra on a global scale is critical.Surface waves investigation and monitoring onboard the Chinese-Fren...The internal energy distribution of waves can be described using ocean-wave spectra.In many ways,obtaining wave spectra on a global scale is critical.Surface waves investigation and monitoring onboard the Chinese-French oceanography satellite is the first space-borne instrument for detecting wave spectra specially,which was launched on October 29,2018.It can avoid the shortage of synthetic aperture radar detection results while still having some problems,especially with the effects of speckle noise.In this study,a method to suppress the speckle noise is proposed.First,the empirical formula for background speckle noise is established.Second,many spatio-temporal representative fluctuation spectra are classified and averaged.Third,rational transfer function filtering is used to obtain speckle noise close to the along-track direction.Finally,a signal-to-noise ratio threshold is used to suppress the abnormal speckle noise.This method solves the problems existing in previous denoising methods,such as excessive denoising in the along-track direction and the inability of some abnormal noises to be denoised in the two-dimensional directional wave spectra.展开更多
The GF-3 satellite was launched on August 10,2016 from the Taiyuan Satellite Launch Center and was put into operation at the end of January,2017.It has acquired nearly 100 thousand C-band multi-polarization ocean and ...The GF-3 satellite was launched on August 10,2016 from the Taiyuan Satellite Launch Center and was put into operation at the end of January,2017.It has acquired nearly 100 thousand C-band multi-polarization ocean and land SAR images,providing data support for many departments covering resource survey,typhoon early warning,disaster assessment,crop yield estimation and polar investigation.Recently,the team led by ZHANG Qingjun from展开更多
With the rapid development of economy, great changes have taken place in our lives, and the quality and level of our lives are constantly improving. However, the problem of environmental pollution is also getting wors...With the rapid development of economy, great changes have taken place in our lives, and the quality and level of our lives are constantly improving. However, the problem of environmental pollution is also getting worse. Environmental issues are related to our survival and development, so it is particularly important to do a good job in protecting the ecological environment. Therefore, it is particularly important to carry out surface water testing, and there are still many problems to be solved in surface water testing. This paper discusses the related problems and countermeasures of surface water detection in environmental monitoring to provide reference for surface water monitoring.展开更多
Zipper hydraulic fracturing in multiple wells with long horizontal sections is a primary solution means to increase the shale gas production rate and efficiency and to reduce the cost in Southern Sichuan Basin.Microse...Zipper hydraulic fracturing in multiple wells with long horizontal sections is a primary solution means to increase the shale gas production rate and efficiency and to reduce the cost in Southern Sichuan Basin.Microseismic based fracturing monitoring can be used for real-time imaging of hydraulic fractures,so it has been widely used to evaluate the fracturing effect of shale gas reservoirs and to direct the optimiza-tion and adjustment of fracturing parameters.In China,however,the microseismic fracturing monitoring on fracturing of shale gas reservoirs cannot be used to evaluate the fracturing results until the fracturing operation in the pad wells is completed according to the parameters which are designed prior to the fracturing monitoring.Its evaluation results can merely provide a guidance for the fracturing parameters of the next pad wells instead of the wells in operation.As a result,the real-time effect of microseismic fracturing monitoring is out of work.In view of this,the fractures induced by zipper hydraulic fracturing in multiple shale gas wells with long horizontal sections in the southern Sichuan Basin,was real-time imaged by using the combined technology of radially arranged microseismic surface monitoring and microseismic well monitoring on the basis of real-time positioning method.The fracturing results were assessed and used in real time for the optimization of prepad fluid parameter,perforation and temporary plugging additive releasing time,so as to effectively avoid repeated fracturing and uneven fracturing effects and improve fracturing stimulation effects.This method is applied in two well groups.It is shown that the average shale gas production rate is increased by 2e5 times.Furthermore,microseismic fracturing real-time monitoring plays a vital role in real-time evaluation of fracturing effect and real-time optimization of fracturing parameters,so it can be used as the reference and should be popularized further.展开更多
Surface engineering of magnesium alloys requires adequate strategies, processes and materials permitting corrosion protection. Liquid formulations containing corrosion inhibitors often are to be optimized according to...Surface engineering of magnesium alloys requires adequate strategies, processes and materials permitting corrosion protection. Liquid formulations containing corrosion inhibitors often are to be optimized according to the demands of the respective substrate and following the service conditions during its application. As an interdisciplinary approach, a combination of several techniques for instantly monitoring or elaborately analyzing the surface state of magnesium was accomplished in order to characterize the performance of new adsorbing sustainable amphiphilic polymers which recently were developed to facilitate a multi-metal corrosion protection approach. The application of established techniques like Contact Angle measurements and X-ray Photoelectron Spectroscopy investigations was supplemented by introducing related and yet faster online-capable and larger-scale techniques like Aerosol Wetting Test and Optically Stimulated Electron Emission. Moreover, an inexpensive setup was configured for scaling the inset and the extent of degradation processes which occur at local electrochemical circuits and lead to hydrogen bubble formation. Using these analytical tools, changes of the surface state of emeried AM50 samples were investigated. Even in contact with water, being a moderate corrosive medium, the online techniques facilitated detecting surface degradation of the unprotected magnesium alloy within some seconds. In contrast, following contact with a 1 weight% formulation of a polymeric corrosion inhibitor, surface monitoring indicated a delay of the onset of degradation processes by approximately two orders of magnitude in time. Mainly based on the spectroscopic investigations, the corrosion inhibiting effects of the investigated polymer are attributed to the adsorption of a primary polymer layer with a thickness of a few nanometers which occurs within some seconds. Immersion of magnesium for several hours brings up a protective film with around ten nanometers thickness.展开更多
The scientific and fair positioning of monitoring locations for surface displacement on slopes is a prerequisite for early warning and forecasting.However,there is no specific provision on how to effectively determine...The scientific and fair positioning of monitoring locations for surface displacement on slopes is a prerequisite for early warning and forecasting.However,there is no specific provision on how to effectively determine the number and location of monitoring points according to the actual deformation characteristics of the slope.There are still some defects in the layout of monitoring points.To this end,based on displacement data series and spatial location information of surface displacement monitoring points,by combining displacement series correlation and spatial distance influence factors,a spatial deformation correlation calculation model of slope based on clustering analysis was proposed to calculate the correlation between different monitoring points,based on which the deformation area of the slope was divided.The redundant monitoring points in each partition were eliminated based on the partition's outcome,and the overall optimal arrangement of slope monitoring points was then achieved.This method scientifically addresses the issues of slope deformation zoning and data gathering overlap.It not only eliminates human subjectivity from slope deformation zoning but also increases the efficiency and accuracy of slope monitoring.In order to verify the effectiveness of the method,a sand-mudstone interbedded CounterTilt excavation slope in the Chongqing city of China was used as the research object.Twenty-four monitoring points deployed on this slope were monitored for surface displacement for 13 months.The spatial location of the monitoring points was discussed.The results show that the proposed method of slope deformation zoning and the optimized placement of monitoring points are feasible.展开更多
The development and application of the ''digital mine'' concept in China depends heavily upon the use of remote sensing data as well as domestic expertise and awareness. Illegal mining of mineral resou...The development and application of the ''digital mine'' concept in China depends heavily upon the use of remote sensing data as well as domestic expertise and awareness. Illegal mining of mineral resources has been a serious long term problem frustrating the Xishimen Iron Ore Mine management. This mine is located in Wu'an county in Hebei province, China. Illegal activities have led to enormous economic losses by interfering with the normal operation of the Xishimen mine and have ruined the surrounding environ- ment and the stability of the Mahe riverbed the crosses the mined area. This paper is based on field recon- naissance taken over many years around the mine area. The ground survey data are integrated with Differential Synthetic Aperture Radar Interferometry (D-InSAR) results from ALOS/PALSAR data to pin- point mining locations. By investigating the relationship between the resulting interferometric deforma- tion pattern and the mining schedule, which is known a priori, areas affected by illegal mining activities are identified. To some extent these areas indicate the location of the illegal site. The results clearly dem- onstrate D-InSAR's ability to cost-effectively monitor illegal mining activities.展开更多
Surface roughness is one of the most critical attributes of machined components,especially those used in high-performance systems.Online surface roughness monitoring offers advancements comparable to post-process insp...Surface roughness is one of the most critical attributes of machined components,especially those used in high-performance systems.Online surface roughness monitoring offers advancements comparable to post-process inspection methods,reducing inspection time and costs and concurrently reducing the likelihood of defects.Currently,online monitoring approaches for surface roughness are constrained by several limitations,including the reliance on handcrafted feature extraction,which necessitates the involvement of human experts and entails time-consuming processes.Moreover,the prediction models trained under one set of cutting conditions exhibit poor performance when applied to different experimental settings.To address these challenges,this work presents a novel deep-learning-assisted online surface roughness monitoring method for ultraprecision fly cutting of copper workpieces under different cutting conditions.Tooltip acceleration signals were acquired during each cutting experiment to develop two datasets,and no handcrafted features were extracted.Five deep learning models were developed and evaluated using standard performance metrics.A convolutional neural network stacked on a long short-term memory network outperformed all other network models,yielding exceptional results,including a mean absolute percentage error as low as 1.51%and an R2value of 96.6%.Furthermore,the robustness of the proposed model was assessed via a validation cohort analysis using experimental data obtained using cutting parameters different from those previously employed.The performance of the model remained consistent and commendable under varied conditions,asserting its applicability in real-world scenarios.展开更多
Subject Code:E01With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Profs.Ding Yi(丁轶)and Luo Jun(罗俊)from the School of Materials Science and Eng...Subject Code:E01With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Profs.Ding Yi(丁轶)and Luo Jun(罗俊)from the School of Materials Science and Engineering,Tianjin University of Technology and Prof.Liu Limin(刘利民)from Beijing展开更多
Spatiotemporal data fusion technologies have been widely used for land surface phenology(LSP)monitoring since it is a low-cost solution to obtain fine-resolution satellite time series.However,the reliability of fused ...Spatiotemporal data fusion technologies have been widely used for land surface phenology(LSP)monitoring since it is a low-cost solution to obtain fine-resolution satellite time series.However,the reliability of fused images is largely affected by land surface heterogeneity and input data.It is unclear whether data fusion can really benefit LSP studies at fine scales.To explore this research question,this study designed a sophisticated simulation experiment to quantify effectiveness of 2 representative data fusion algorithms,namely,pair-based Spatial and Temporal Adaptive Reflectance Fusion Model(STARFM)and time series-based Spatiotemporal fusion method to Simultaneously generate Full-length normalized difference vegetation Index Time series(SSFIT)by fusing Landsat and Moderate Resolution Imaging Spectroradiometer(MODIS)data in extracting pixel-wise spring phenology(i.e.,the start of the growing season,SOS)and its spatial gradient and temporal variation.Our results reveal that:(a)STARFM can improve the accuracy of pixel-wise SOS by up to 74.47%and temporal variation by up to 59.13%,respectively,compared with only using Landsat images,but it can hardly improve the retrieval of spatial gradient.For SSFIT,the accuracy of pixel-wise SOS,spatial gradient,and temporal variation can be improved by up to 139.20%,26.36%,and 162.30%,respectively;(b)the accuracy improvement introduced by fusion algorithms decreases with the number of available Landsat images per year,and it has a large variation with the same number of available Landsat images,and(c)this large variation is highly related to the temporal distributions of available Landsat images,suggesting that fusion algorithms can improve SOS accuracy only when cloud-free Landsat images cannot capture key vegetation growth period.This study calls for caution with the use of data fusion in LSP studies at fine scales.展开更多
Improvements to body-surface physiological monitoring ability including real-time,accuracy and integration,are essential to meet the expansive demands for personal healthcare.As part of this,simultaneous monitoring of...Improvements to body-surface physiological monitoring ability including real-time,accuracy and integration,are essential to meet the expansive demands for personal healthcare.As part of this,simultaneous monitoring of sweat metabolites and body temperature offers an exciting path to maximizing diagnostic precision and minimizing morbidity rates.Herein,we report a high-performance biomarker-temperature sensor made of a single As_(3)Se_(5)Te_(2)chalcogenide glass fiber to monitor physiology evolution on body-surface.The sensor integrates efficient thermal resistance and fiber evanescent wave effects,permitting the independent sensing of temperature and biomarkers with an ultrahigh temperature coefficient of resistance(−5.84%K^(–1)),rapid temperature response(0.3 s)and excellent IR sensing sensitivity.Moreover,by attaching a fiber to the wrist,we demonstrate simultaneous observation of both sweat metabolite(urea and lactate)and temperature changes during exercise.This illuminating sensing method will provide crucial capabilities in physiological monitoring and pave the way for advanced personalized diagnostic.展开更多
Naise sppeaion s an important part of micrseimic momiloring techomology.Sigmul and naise can be separated by denoisig and fihering to improve the subesequent amlys.In this paper,we popoase a new denoising method besed...Naise sppeaion s an important part of micrseimic momiloring techomology.Sigmul and naise can be separated by denoisig and fihering to improve the subesequent amlys.In this paper,we popoase a new denoising method besed on comvolutional blind denoising netwonk(CBDNet).The method is pnily modied for image denoising netwarck CBDNet to make it suitble for ome dimernsional data denoising At present,moast aof the existing ftering methods are proposed for the Gausian white nmoise denoising h comtrast the propesed method also leams the wind moise mnstruction noix trafc noie and mixed noise through the sategy of reidual leamig.The full anvohution subnetwark.is used to esimate the noise level,which significandy improves the sigmal.to nise mio and ibs perfommance of removing the comelated noises The model is trmined with dffent types of real naise and randoam noises The denoising esult is evaluated by comespanding indexes and compured with ofher denoing methods.The reuls show that the poposed method has better demoising performance than raditiomal methods,and it has a superior noise supession level for ail well construction noise and mixed noise.The proposed method can supress the inerference of time frequeney owedapped end to end and still he nmoise suppesion and event detection capability even if the sigmul is superimpased on other types of noie.展开更多
Land cover products provide critical information for monitoring and analyzing land surface changes.However,notable disagreement and incompatible classification systems among existing land cover products bring challeng...Land cover products provide critical information for monitoring and analyzing land surface changes.However,notable disagreement and incompatible classification systems among existing land cover products bring challenges in using them.Here,we developed a hierarchical International Geosphere-Biosphere Programme(IGBP)classification system and integrated four widely used land cover products(i.e.,MODIS-IGBP,ESA-CCI,GlobeLand30,and GLC_FCS30)based on their accuracy against a collection of global reference samples.We generated a hybrid global annual land cover product(HYBMAP)with~1 km(1/120°,30″)spatial resolution from 2000 to 2020.The HYBMAP integrates information from the four products of high-and medium-resolution and reduces the disagreement between them by up to 20.1%.The overall accuracy of the HYBMAP is 75.5%,which is higher than the best of the four products(MODIS-IGBP,70.9%).HYBMAP also integrates the temporal change information from the four products and identifies a faster growth of built-up lands.The HYBMAP provides more consistent and reliable global land cover time series data for global change research.It is free to access at https://doi.org/10.5281/zenodo.10488191.展开更多
文摘The internal energy distribution of waves can be described using ocean-wave spectra.In many ways,obtaining wave spectra on a global scale is critical.Surface waves investigation and monitoring onboard the Chinese-French oceanography satellite is the first space-borne instrument for detecting wave spectra specially,which was launched on October 29,2018.It can avoid the shortage of synthetic aperture radar detection results while still having some problems,especially with the effects of speckle noise.In this study,a method to suppress the speckle noise is proposed.First,the empirical formula for background speckle noise is established.Second,many spatio-temporal representative fluctuation spectra are classified and averaged.Third,rational transfer function filtering is used to obtain speckle noise close to the along-track direction.Finally,a signal-to-noise ratio threshold is used to suppress the abnormal speckle noise.This method solves the problems existing in previous denoising methods,such as excessive denoising in the along-track direction and the inability of some abnormal noises to be denoised in the two-dimensional directional wave spectra.
文摘The GF-3 satellite was launched on August 10,2016 from the Taiyuan Satellite Launch Center and was put into operation at the end of January,2017.It has acquired nearly 100 thousand C-band multi-polarization ocean and land SAR images,providing data support for many departments covering resource survey,typhoon early warning,disaster assessment,crop yield estimation and polar investigation.Recently,the team led by ZHANG Qingjun from
文摘With the rapid development of economy, great changes have taken place in our lives, and the quality and level of our lives are constantly improving. However, the problem of environmental pollution is also getting worse. Environmental issues are related to our survival and development, so it is particularly important to do a good job in protecting the ecological environment. Therefore, it is particularly important to carry out surface water testing, and there are still many problems to be solved in surface water testing. This paper discusses the related problems and countermeasures of surface water detection in environmental monitoring to provide reference for surface water monitoring.
基金Supported by the National Science and Technology Major Project“Real-time hydraulic fracturing monitoring and integrated geologic-engineering evaluation”(Grant No.2016ZX05023004).
文摘Zipper hydraulic fracturing in multiple wells with long horizontal sections is a primary solution means to increase the shale gas production rate and efficiency and to reduce the cost in Southern Sichuan Basin.Microseismic based fracturing monitoring can be used for real-time imaging of hydraulic fractures,so it has been widely used to evaluate the fracturing effect of shale gas reservoirs and to direct the optimiza-tion and adjustment of fracturing parameters.In China,however,the microseismic fracturing monitoring on fracturing of shale gas reservoirs cannot be used to evaluate the fracturing results until the fracturing operation in the pad wells is completed according to the parameters which are designed prior to the fracturing monitoring.Its evaluation results can merely provide a guidance for the fracturing parameters of the next pad wells instead of the wells in operation.As a result,the real-time effect of microseismic fracturing monitoring is out of work.In view of this,the fractures induced by zipper hydraulic fracturing in multiple shale gas wells with long horizontal sections in the southern Sichuan Basin,was real-time imaged by using the combined technology of radially arranged microseismic surface monitoring and microseismic well monitoring on the basis of real-time positioning method.The fracturing results were assessed and used in real time for the optimization of prepad fluid parameter,perforation and temporary plugging additive releasing time,so as to effectively avoid repeated fracturing and uneven fracturing effects and improve fracturing stimulation effects.This method is applied in two well groups.It is shown that the average shale gas production rate is increased by 2e5 times.Furthermore,microseismic fracturing real-time monitoring plays a vital role in real-time evaluation of fracturing effect and real-time optimization of fracturing parameters,so it can be used as the reference and should be popularized further.
基金Borders(Ciencia sem Fronteiras,proc.L.M.G.Goncalves 88888.021780/2013-00,L.C.Sanchez 88888.021800/2013-00 and S.Stamboroski 88888.020610/2013-00)Coordination of Improvement of Higher Education Personnel(CAPES-Brazil)and Consejo Nacional para Investigaciones Científicas y Tecnologicas de Costa Rica.(CONICIT)for the funding+1 种基金the German Federal Ministry of Economics and Technology(BMWi)under the ZIM programme(Zentrales Innovationsprogramm Mittelstand-ZIM)the“KABA”project(funding reference KF2139502 HA9)carried out with Straetmans High TAC GmbH
文摘Surface engineering of magnesium alloys requires adequate strategies, processes and materials permitting corrosion protection. Liquid formulations containing corrosion inhibitors often are to be optimized according to the demands of the respective substrate and following the service conditions during its application. As an interdisciplinary approach, a combination of several techniques for instantly monitoring or elaborately analyzing the surface state of magnesium was accomplished in order to characterize the performance of new adsorbing sustainable amphiphilic polymers which recently were developed to facilitate a multi-metal corrosion protection approach. The application of established techniques like Contact Angle measurements and X-ray Photoelectron Spectroscopy investigations was supplemented by introducing related and yet faster online-capable and larger-scale techniques like Aerosol Wetting Test and Optically Stimulated Electron Emission. Moreover, an inexpensive setup was configured for scaling the inset and the extent of degradation processes which occur at local electrochemical circuits and lead to hydrogen bubble formation. Using these analytical tools, changes of the surface state of emeried AM50 samples were investigated. Even in contact with water, being a moderate corrosive medium, the online techniques facilitated detecting surface degradation of the unprotected magnesium alloy within some seconds. In contrast, following contact with a 1 weight% formulation of a polymeric corrosion inhibitor, surface monitoring indicated a delay of the onset of degradation processes by approximately two orders of magnitude in time. Mainly based on the spectroscopic investigations, the corrosion inhibiting effects of the investigated polymer are attributed to the adsorption of a primary polymer layer with a thickness of a few nanometers which occurs within some seconds. Immersion of magnesium for several hours brings up a protective film with around ten nanometers thickness.
基金funding from the National Natural Science Foundation of China(No.41572308)。
文摘The scientific and fair positioning of monitoring locations for surface displacement on slopes is a prerequisite for early warning and forecasting.However,there is no specific provision on how to effectively determine the number and location of monitoring points according to the actual deformation characteristics of the slope.There are still some defects in the layout of monitoring points.To this end,based on displacement data series and spatial location information of surface displacement monitoring points,by combining displacement series correlation and spatial distance influence factors,a spatial deformation correlation calculation model of slope based on clustering analysis was proposed to calculate the correlation between different monitoring points,based on which the deformation area of the slope was divided.The redundant monitoring points in each partition were eliminated based on the partition's outcome,and the overall optimal arrangement of slope monitoring points was then achieved.This method scientifically addresses the issues of slope deformation zoning and data gathering overlap.It not only eliminates human subjectivity from slope deformation zoning but also increases the efficiency and accuracy of slope monitoring.In order to verify the effectiveness of the method,a sand-mudstone interbedded CounterTilt excavation slope in the Chongqing city of China was used as the research object.Twenty-four monitoring points deployed on this slope were monitored for surface displacement for 13 months.The spatial location of the monitoring points was discussed.The results show that the proposed method of slope deformation zoning and the optimized placement of monitoring points are feasible.
基金supported by the National Hi-Tech Research and Development Program of China (No. 2009AA11Z105)the sponsors of Hanxing Iron Ore Mine Administration Bureau for providing the research funds,insitu test assistance and monitor work
文摘The development and application of the ''digital mine'' concept in China depends heavily upon the use of remote sensing data as well as domestic expertise and awareness. Illegal mining of mineral resources has been a serious long term problem frustrating the Xishimen Iron Ore Mine management. This mine is located in Wu'an county in Hebei province, China. Illegal activities have led to enormous economic losses by interfering with the normal operation of the Xishimen mine and have ruined the surrounding environ- ment and the stability of the Mahe riverbed the crosses the mined area. This paper is based on field recon- naissance taken over many years around the mine area. The ground survey data are integrated with Differential Synthetic Aperture Radar Interferometry (D-InSAR) results from ALOS/PALSAR data to pin- point mining locations. By investigating the relationship between the resulting interferometric deforma- tion pattern and the mining schedule, which is known a priori, areas affected by illegal mining activities are identified. To some extent these areas indicate the location of the illegal site. The results clearly dem- onstrate D-InSAR's ability to cost-effectively monitor illegal mining activities.
基金supported by the Science Challenge Project(Grant No.JDZZ2016006-0102)。
文摘Surface roughness is one of the most critical attributes of machined components,especially those used in high-performance systems.Online surface roughness monitoring offers advancements comparable to post-process inspection methods,reducing inspection time and costs and concurrently reducing the likelihood of defects.Currently,online monitoring approaches for surface roughness are constrained by several limitations,including the reliance on handcrafted feature extraction,which necessitates the involvement of human experts and entails time-consuming processes.Moreover,the prediction models trained under one set of cutting conditions exhibit poor performance when applied to different experimental settings.To address these challenges,this work presents a novel deep-learning-assisted online surface roughness monitoring method for ultraprecision fly cutting of copper workpieces under different cutting conditions.Tooltip acceleration signals were acquired during each cutting experiment to develop two datasets,and no handcrafted features were extracted.Five deep learning models were developed and evaluated using standard performance metrics.A convolutional neural network stacked on a long short-term memory network outperformed all other network models,yielding exceptional results,including a mean absolute percentage error as low as 1.51%and an R2value of 96.6%.Furthermore,the robustness of the proposed model was assessed via a validation cohort analysis using experimental data obtained using cutting parameters different from those previously employed.The performance of the model remained consistent and commendable under varied conditions,asserting its applicability in real-world scenarios.
文摘Subject Code:E01With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Profs.Ding Yi(丁轶)and Luo Jun(罗俊)from the School of Materials Science and Engineering,Tianjin University of Technology and Prof.Liu Limin(刘利民)from Beijing
基金supported by the National Natural Science Foundation of China(Project Nos.42271331 and 42022060)The Hong Kong Polytechnic University(Project Nos.4-ZZND and Q-CDBP).
文摘Spatiotemporal data fusion technologies have been widely used for land surface phenology(LSP)monitoring since it is a low-cost solution to obtain fine-resolution satellite time series.However,the reliability of fused images is largely affected by land surface heterogeneity and input data.It is unclear whether data fusion can really benefit LSP studies at fine scales.To explore this research question,this study designed a sophisticated simulation experiment to quantify effectiveness of 2 representative data fusion algorithms,namely,pair-based Spatial and Temporal Adaptive Reflectance Fusion Model(STARFM)and time series-based Spatiotemporal fusion method to Simultaneously generate Full-length normalized difference vegetation Index Time series(SSFIT)by fusing Landsat and Moderate Resolution Imaging Spectroradiometer(MODIS)data in extracting pixel-wise spring phenology(i.e.,the start of the growing season,SOS)and its spatial gradient and temporal variation.Our results reveal that:(a)STARFM can improve the accuracy of pixel-wise SOS by up to 74.47%and temporal variation by up to 59.13%,respectively,compared with only using Landsat images,but it can hardly improve the retrieval of spatial gradient.For SSFIT,the accuracy of pixel-wise SOS,spatial gradient,and temporal variation can be improved by up to 139.20%,26.36%,and 162.30%,respectively;(b)the accuracy improvement introduced by fusion algorithms decreases with the number of available Landsat images per year,and it has a large variation with the same number of available Landsat images,and(c)this large variation is highly related to the temporal distributions of available Landsat images,suggesting that fusion algorithms can improve SOS accuracy only when cloud-free Landsat images cannot capture key vegetation growth period.This study calls for caution with the use of data fusion in LSP studies at fine scales.
基金supported by the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(Grant No.2025C01166)National Natural Science Foundation of China(Grant Nos.62105168,62122039)+2 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LY23F050006)Ningbo Natural Science Foundation(Grant No.2024J460)sponsored by K.C.Wong Magna Fund in Ningbo University.
文摘Improvements to body-surface physiological monitoring ability including real-time,accuracy and integration,are essential to meet the expansive demands for personal healthcare.As part of this,simultaneous monitoring of sweat metabolites and body temperature offers an exciting path to maximizing diagnostic precision and minimizing morbidity rates.Herein,we report a high-performance biomarker-temperature sensor made of a single As_(3)Se_(5)Te_(2)chalcogenide glass fiber to monitor physiology evolution on body-surface.The sensor integrates efficient thermal resistance and fiber evanescent wave effects,permitting the independent sensing of temperature and biomarkers with an ultrahigh temperature coefficient of resistance(−5.84%K^(–1)),rapid temperature response(0.3 s)and excellent IR sensing sensitivity.Moreover,by attaching a fiber to the wrist,we demonstrate simultaneous observation of both sweat metabolite(urea and lactate)and temperature changes during exercise.This illuminating sensing method will provide crucial capabilities in physiological monitoring and pave the way for advanced personalized diagnostic.
基金financially supported in part by National Natural Science Foundation of China(42272204)the National Key Research and Development Program of China(2018YFB0605503)the Fundamental Research Funds for the Central Universities,China under Grant(2021JCCXDC02).
文摘Naise sppeaion s an important part of micrseimic momiloring techomology.Sigmul and naise can be separated by denoisig and fihering to improve the subesequent amlys.In this paper,we popoase a new denoising method besed on comvolutional blind denoising netwonk(CBDNet).The method is pnily modied for image denoising netwarck CBDNet to make it suitble for ome dimernsional data denoising At present,moast aof the existing ftering methods are proposed for the Gausian white nmoise denoising h comtrast the propesed method also leams the wind moise mnstruction noix trafc noie and mixed noise through the sategy of reidual leamig.The full anvohution subnetwark.is used to esimate the noise level,which significandy improves the sigmal.to nise mio and ibs perfommance of removing the comelated noises The model is trmined with dffent types of real naise and randoam noises The denoising esult is evaluated by comespanding indexes and compured with ofher denoing methods.The reuls show that the poposed method has better demoising performance than raditiomal methods,and it has a superior noise supession level for ail well construction noise and mixed noise.The proposed method can supress the inerference of time frequeney owedapped end to end and still he nmoise suppesion and event detection capability even if the sigmul is superimpased on other types of noie.
基金supported by the National Natural Science Foundation of China(42271104)the Shenzhen Funda-mental Research Program(GXWD20201231165807007-20200814213435001)+1 种基金the Shenzhen Science and Tech nology Program(JCYJ20220531093201004)Shenzhen Science and Technology Program(KQTD20221101093604016).
文摘Land cover products provide critical information for monitoring and analyzing land surface changes.However,notable disagreement and incompatible classification systems among existing land cover products bring challenges in using them.Here,we developed a hierarchical International Geosphere-Biosphere Programme(IGBP)classification system and integrated four widely used land cover products(i.e.,MODIS-IGBP,ESA-CCI,GlobeLand30,and GLC_FCS30)based on their accuracy against a collection of global reference samples.We generated a hybrid global annual land cover product(HYBMAP)with~1 km(1/120°,30″)spatial resolution from 2000 to 2020.The HYBMAP integrates information from the four products of high-and medium-resolution and reduces the disagreement between them by up to 20.1%.The overall accuracy of the HYBMAP is 75.5%,which is higher than the best of the four products(MODIS-IGBP,70.9%).HYBMAP also integrates the temporal change information from the four products and identifies a faster growth of built-up lands.The HYBMAP provides more consistent and reliable global land cover time series data for global change research.It is free to access at https://doi.org/10.5281/zenodo.10488191.
