The advent of convolutional neural networks has led to remarkable progress in dense stereo labeling problem,achieving superior performance over the traditional methods.However,the ill-posed nature of stereo matching m...The advent of convolutional neural networks has led to remarkable progress in dense stereo labeling problem,achieving superior performance over the traditional methods.However,the ill-posed nature of stereo matching makes noise(outliers)in winner-takes-all(WTA)disparity maps inevitable.This paper presents a robust statistical approach to noise detection and refinement of WTA disparity maps.In the context of noise detection,the input noisy WTA disparity map is segmented into regular grid cells(regions)with the aim of leveraging Markov random field(MRF)to infer candidate disparity labels.However,there are two key problems:there can be large severe outliers in the regions;second,the regular partition process may produce regions with mixed disparity distributions.To overcome these problems,we optimize a robust objective function over the segmented disparity map.By obtaining the optimal solution of the objective function through a maximum a posteriori estimation in a probabilistic model,we are able to infer MRF candidate disparity labels.We then apply a soft-segmentation constraint on the estimated MRF candidate disparity labels to describe and detect outliers in the disparity map.Next,an edge-preserving statistical inference that leverages the joint statistics of the disparity map and its guidance reference image is used to select correct candidate disparity for each detected outlier.Finally,a weighted median filter is applied to remove small spikes and irregularities in the resulting disparity map.Rigorous and comprehensive experiments showed that the proposed method is distributionally robust and outlier resistant,and can effectively detect and correct outliers in disparity maps.Middlebury evaluation benchmark validated the competitive performance of the proposed method.展开更多
Cornus wilsoniana W.is a woody oil plant with high oil content and strong hypolipidemic effects,making it a valuable species for medicinal,landscaping,and ecological purposes in China.To advance genetic research on th...Cornus wilsoniana W.is a woody oil plant with high oil content and strong hypolipidemic effects,making it a valuable species for medicinal,landscaping,and ecological purposes in China.To advance genetic research on this species,we employed PacBio together with Hi-C data to create a draft genome assembly for C.wilsoniana.Based on an 11-chromosome anchored chromosome-level assembly,the estimated genome size was determined to be 843.51 Mb.The N50 contig size and N50 scaffold size were calculated to be 4.49 and 78.00 Mb,respectively.Furthermore,30474 protein-coding genes were annotated.Comparative genomics analysis revealed that C.wilsoniana diverged from its closest species∼12.46 million years ago(Mya).Furthermore,the divergence between Cornaceae and Nyssaceae occurred>62.22 Mya.We also found evidence of whole-genome duplication events and whole-genome triplicationγ,occurring at∼44.90 and 115.86 Mya.We further inferred the origins of chromosomes,which sheds light on the complex evolutionary history of the karyotype of C.wilsoniana.Through transcriptional and metabolic analysis,we identified two FAD2 homologous genes that may play a crucial role in controlling the oleic to linoleic acid ratio.We further investigated the correlation between metabolites and genes and identified 33 MADS-TF homologous genes that may affect f lower morphology in C.wilsoniana.Overall,this study lays the groundwork for future research aimed at identifying the genetic basis of crucial traits in C.wilsoniana.展开更多
The solid Earth responds elastically to terrestrial water storage(TWS)changes.Here global positioning system(GPS)vertical position data at 31 stations from the crustal movement observation network of China(CMONOC)from...The solid Earth responds elastically to terrestrial water storage(TWS)changes.Here global positioning system(GPS)vertical position data at 31 stations from the crustal movement observation network of China(CMONOC)from August 2010 to December 2016 are used to detect droughts in Southwest China.Monthly GPS vertical position displacements respond negatively to precipitation changes and TWS changes observed by gravity recovery and climate experiments(GRACE)as well as river water level variations.GPS vertical position anomalies(the non-seasonal term)are well correlated negatively(correlations of about-0.70)with the commonly used meteorological composite index(CI)in China and the GRACE drought severity index(GRACE-DSI),but less correlated with the standardized precipitation evapotranspiration index(SPEI).Compared to CI,GPS vertical position anomalies have the advantage of detecting droughts caused by abrupt precipitation deficits in a short time.GRACE-DSI is less accurate in drought monitoring for some periods due to the missing data,while the severity of abrupt precipitation absent in some cases can be overestimated from SPEI with big variability.This study shows the reliability and advantages of GPS data in drought monitoring.展开更多
The Tibet Plateau is one of the regions with the richest solar energy resources in the world.In the process of achieving carbon neutrality in China,the development and utilization of solar energy resources in the regi...The Tibet Plateau is one of the regions with the richest solar energy resources in the world.In the process of achieving carbon neutrality in China,the development and utilization of solar energy resources in the region will play an important role.In this study,the gridded solar resource data with 1km resolution in Xizang were obtained by spatial correction and downscaling of SMARTS model.On this basis,the spatial and temporal distribution characteristics of solar energy resources in the region in the past 30 years(1991–2020)are finely evaluated,and the annual global horizontal radiation resource is calculated.The results show that:1)The average annual global horizontal radiation amount in Xizang is 1816 kWh/m^(2).More than 60%of the area belongs to the“Most abundant”(GHI≥1750 kWh/m^(2))area of China’s solar energy resources category A,and nearly 40%belongs to the“Quite abundant”(1400≤GHI<1750)area of China’s solar energy resource category B.2)In space,the solar energy resources in Xizang increased gradually from north to south and from east to west.Lhasa,Central and Eastern Shigatse,Shannan,and Southwestern Ali are the most abundant cities,with a maximum annual radiation level of 2189 kWh/m2.3)In terms of time,the total horizontal radiation in Xizang was the highest in May and the lowest in December.74%of the total area belongs to the“Very stable”(R_(w)≥0.47)area of solar resource stability category A,and 26%belongs to the“stable”(0.36≤R_(w)<0.47)area of solar resource stability category B.Solar energy resources in the region show the characteristics of both strong and stable.Average solar energy resources in the region have shown a fluctuating downward trend over the past 30 years,with an average decline of about 12.86(kWh/m2)per decade.4)In terms of solar radiation resources reaching the earth’s surface,the theoretical total amount of annual horizontal radiation in Xizang is about 240.07 billion tons of standard coal or 222.91 billion kilowatts on average.展开更多
This paper analyzes optimization algorithms of assembly time for a multi-head mounter.The algorithm in this paper is composed of four steps.First,it assigns the components to feeders based on the"one-to-many mapp...This paper analyzes optimization algorithms of assembly time for a multi-head mounter.The algorithm in this paper is composed of four steps.First,it assigns the components to feeders based on the"one-to-many mapping".Secondly,it assigns nozzles to heads by making full use of the"on-the-fly nozzle change"heads.Thirdly,it Qrganizes the feeder groups so that the heads can pick and place components group by group.Finally,it assigns feeder groups to slots.The result demonstrates that the algorithm has good performance in practice.展开更多
Rapid urban sprawl and re-construction of old towns have been leading to great changes of land use in cities of China. To witness short-term urban land use changes, rapid or real time remote sensing images and effecti...Rapid urban sprawl and re-construction of old towns have been leading to great changes of land use in cities of China. To witness short-term urban land use changes, rapid or real time remote sensing images and effective detection methods are required. With the availability of short repeat cycle, relatively high spatial resolution, and weather-independent Synthetic Aperture Radar (SAR) remotely sensed data, detection of short-term urban land use changes becomes possible. This paper adopts newly released Sentinel-1 SAR data for urban change detection in Tianhe District of Guangzhou City in Southern China, where dramatic urban redevelopment practices have been taking place in past years. An integrative method that combines the SAR time series data and a spectral angle mapping (SAM) was developed and applied to detect the short-term land use changes. Linear trend transformations of the SAR time series data were first conducted to reveal patterns of substantial changes. Spectral mixture analysis was then conducted to extract temporal endmembers to reflect the land development patterns based on the SAR backscattering intensities over time. Moreover, SAM was applied to extract the information of significant increase and decrease patterns. The results of validation and method comparison showed a significant capability of both the proposed method and the SAR time series images for detecting the short-term urban land use changes. The method received an overall accuracy of 78%, being more accurate than that using a bi-temporal image change detection method. The results revealed land use conversions due to the removal of old buildings and their replacement by new construction. This implies that SAR time series data reflects the spatiotemporal evolution of urban constructed areas within a short time period and this study provided the potential for detecting changes that requires continuously short-term capability, and could be potential in other landscapes.展开更多
基金the 2020 Guangdong International Cooperation Project(No.2019A050510007).
文摘The advent of convolutional neural networks has led to remarkable progress in dense stereo labeling problem,achieving superior performance over the traditional methods.However,the ill-posed nature of stereo matching makes noise(outliers)in winner-takes-all(WTA)disparity maps inevitable.This paper presents a robust statistical approach to noise detection and refinement of WTA disparity maps.In the context of noise detection,the input noisy WTA disparity map is segmented into regular grid cells(regions)with the aim of leveraging Markov random field(MRF)to infer candidate disparity labels.However,there are two key problems:there can be large severe outliers in the regions;second,the regular partition process may produce regions with mixed disparity distributions.To overcome these problems,we optimize a robust objective function over the segmented disparity map.By obtaining the optimal solution of the objective function through a maximum a posteriori estimation in a probabilistic model,we are able to infer MRF candidate disparity labels.We then apply a soft-segmentation constraint on the estimated MRF candidate disparity labels to describe and detect outliers in the disparity map.Next,an edge-preserving statistical inference that leverages the joint statistics of the disparity map and its guidance reference image is used to select correct candidate disparity for each detected outlier.Finally,a weighted median filter is applied to remove small spikes and irregularities in the resulting disparity map.Rigorous and comprehensive experiments showed that the proposed method is distributionally robust and outlier resistant,and can effectively detect and correct outliers in disparity maps.Middlebury evaluation benchmark validated the competitive performance of the proposed method.
基金supported by the National Natural Science Foundation of China(31770767,32070656,32070677 and 32270709)Foundation of State Key Laboratory of Utilization of Woody Oil Resource(GZKF202201)+1 种基金Hunan Province Key Research and Development Program Project(2018NK2044)Jiangsu Collaborative Innovation Center for Modern Crop Production and Collaborative Innovation Center for Modern Crop Production cosponsored by province and ministry.
文摘Cornus wilsoniana W.is a woody oil plant with high oil content and strong hypolipidemic effects,making it a valuable species for medicinal,landscaping,and ecological purposes in China.To advance genetic research on this species,we employed PacBio together with Hi-C data to create a draft genome assembly for C.wilsoniana.Based on an 11-chromosome anchored chromosome-level assembly,the estimated genome size was determined to be 843.51 Mb.The N50 contig size and N50 scaffold size were calculated to be 4.49 and 78.00 Mb,respectively.Furthermore,30474 protein-coding genes were annotated.Comparative genomics analysis revealed that C.wilsoniana diverged from its closest species∼12.46 million years ago(Mya).Furthermore,the divergence between Cornaceae and Nyssaceae occurred>62.22 Mya.We also found evidence of whole-genome duplication events and whole-genome triplicationγ,occurring at∼44.90 and 115.86 Mya.We further inferred the origins of chromosomes,which sheds light on the complex evolutionary history of the karyotype of C.wilsoniana.Through transcriptional and metabolic analysis,we identified two FAD2 homologous genes that may play a crucial role in controlling the oleic to linoleic acid ratio.We further investigated the correlation between metabolites and genes and identified 33 MADS-TF homologous genes that may affect f lower morphology in C.wilsoniana.Overall,this study lays the groundwork for future research aimed at identifying the genetic basis of crucial traits in C.wilsoniana.
基金National Natural Science Foundation of China(Nos.41604017,42004013)Guangdong Natural Science Foundation(No.2019A1515011268)+1 种基金Foundation of Young Creative Talents in Higher Education of Guangdong Province(No.2019KQNCX009)Open fund of Guangxi Key Laboratory of Spatial Information and Geomatics(No.19-050-11-03)。
文摘The solid Earth responds elastically to terrestrial water storage(TWS)changes.Here global positioning system(GPS)vertical position data at 31 stations from the crustal movement observation network of China(CMONOC)from August 2010 to December 2016 are used to detect droughts in Southwest China.Monthly GPS vertical position displacements respond negatively to precipitation changes and TWS changes observed by gravity recovery and climate experiments(GRACE)as well as river water level variations.GPS vertical position anomalies(the non-seasonal term)are well correlated negatively(correlations of about-0.70)with the commonly used meteorological composite index(CI)in China and the GRACE drought severity index(GRACE-DSI),but less correlated with the standardized precipitation evapotranspiration index(SPEI).Compared to CI,GPS vertical position anomalies have the advantage of detecting droughts caused by abrupt precipitation deficits in a short time.GRACE-DSI is less accurate in drought monitoring for some periods due to the missing data,while the severity of abrupt precipitation absent in some cases can be overestimated from SPEI with big variability.This study shows the reliability and advantages of GPS data in drought monitoring.
基金supported by the Major Science and Technology Project of the Science and Technology Department of Tibet under Grant Number XZ202101ZD0015Gthe Second Tibet Plateau Scientific Expedition and Research Program(STEP)under Grant Number 2019QZKK0804.
文摘The Tibet Plateau is one of the regions with the richest solar energy resources in the world.In the process of achieving carbon neutrality in China,the development and utilization of solar energy resources in the region will play an important role.In this study,the gridded solar resource data with 1km resolution in Xizang were obtained by spatial correction and downscaling of SMARTS model.On this basis,the spatial and temporal distribution characteristics of solar energy resources in the region in the past 30 years(1991–2020)are finely evaluated,and the annual global horizontal radiation resource is calculated.The results show that:1)The average annual global horizontal radiation amount in Xizang is 1816 kWh/m^(2).More than 60%of the area belongs to the“Most abundant”(GHI≥1750 kWh/m^(2))area of China’s solar energy resources category A,and nearly 40%belongs to the“Quite abundant”(1400≤GHI<1750)area of China’s solar energy resource category B.2)In space,the solar energy resources in Xizang increased gradually from north to south and from east to west.Lhasa,Central and Eastern Shigatse,Shannan,and Southwestern Ali are the most abundant cities,with a maximum annual radiation level of 2189 kWh/m2.3)In terms of time,the total horizontal radiation in Xizang was the highest in May and the lowest in December.74%of the total area belongs to the“Very stable”(R_(w)≥0.47)area of solar resource stability category A,and 26%belongs to the“stable”(0.36≤R_(w)<0.47)area of solar resource stability category B.Solar energy resources in the region show the characteristics of both strong and stable.Average solar energy resources in the region have shown a fluctuating downward trend over the past 30 years,with an average decline of about 12.86(kWh/m2)per decade.4)In terms of solar radiation resources reaching the earth’s surface,the theoretical total amount of annual horizontal radiation in Xizang is about 240.07 billion tons of standard coal or 222.91 billion kilowatts on average.
基金supported by the special invite public bidding project of Key Equipment of Precision Manufacture of Guangdong Province of China(No.20041A01).
文摘This paper analyzes optimization algorithms of assembly time for a multi-head mounter.The algorithm in this paper is composed of four steps.First,it assigns the components to feeders based on the"one-to-many mapping".Secondly,it assigns nozzles to heads by making full use of the"on-the-fly nozzle change"heads.Thirdly,it Qrganizes the feeder groups so that the heads can pick and place components group by group.Finally,it assigns feeder groups to slots.The result demonstrates that the algorithm has good performance in practice.
基金Key Program of the National Natural Science Foundation of China (Grant No. U1301253)Guangdong Provincial Science and Technology Project (Nos. 2017A050501031 and2017A040406022)+1 种基金Guangzhou Science and Technology Projects (Nos. 201807010048 and 201804020034)the International Postdoctoral Exchange Fellowship Program 2017 (No. 20170029). The authors would like to express their thanks to European Space Agency for providing Sentinel-1 SAR data as well as ESA-SNAP software in conducting research, our colleagues Haiyan Deng and Li Zhao for their assistance in collecting field validation, and processing images, and the colleagues from the Guangzhou Urban Renewal Bureau for their good suggestions. We also would like to thank the editors and anonymous reviewers for their instructive comments.
文摘Rapid urban sprawl and re-construction of old towns have been leading to great changes of land use in cities of China. To witness short-term urban land use changes, rapid or real time remote sensing images and effective detection methods are required. With the availability of short repeat cycle, relatively high spatial resolution, and weather-independent Synthetic Aperture Radar (SAR) remotely sensed data, detection of short-term urban land use changes becomes possible. This paper adopts newly released Sentinel-1 SAR data for urban change detection in Tianhe District of Guangzhou City in Southern China, where dramatic urban redevelopment practices have been taking place in past years. An integrative method that combines the SAR time series data and a spectral angle mapping (SAM) was developed and applied to detect the short-term land use changes. Linear trend transformations of the SAR time series data were first conducted to reveal patterns of substantial changes. Spectral mixture analysis was then conducted to extract temporal endmembers to reflect the land development patterns based on the SAR backscattering intensities over time. Moreover, SAM was applied to extract the information of significant increase and decrease patterns. The results of validation and method comparison showed a significant capability of both the proposed method and the SAR time series images for detecting the short-term urban land use changes. The method received an overall accuracy of 78%, being more accurate than that using a bi-temporal image change detection method. The results revealed land use conversions due to the removal of old buildings and their replacement by new construction. This implies that SAR time series data reflects the spatiotemporal evolution of urban constructed areas within a short time period and this study provided the potential for detecting changes that requires continuously short-term capability, and could be potential in other landscapes.
