Geolocalization is a crucial process that leverages environmental information and contextual data to accurately identify a position.In particular,cross-view geolocalization utilizes images from various perspectives,su...Geolocalization is a crucial process that leverages environmental information and contextual data to accurately identify a position.In particular,cross-view geolocalization utilizes images from various perspectives,such as satellite and ground-level images,which are relevant for applications like robotics navigation and autonomous navigation.In this research,we propose a methodology that integrates cross-view geolocalization estimation with a land cover semantic segmentation map.Our solution demonstrates comparable performance to state-of-the-art methods,exhibiting enhanced stability and consistency regardless of the street view location or the dataset used.Additionally,our method generates a focused discrete probability distribution that acts as a heatmap.This heatmap effectively filters out incorrect and unlikely regions,enhancing the reliability of our estimations.Code is available at https://github.com/nathanxavier/CVSegGuide.展开更多
Water is an essential component of the Earth’s climate,but monitoring its properties using autonomous underwater sampling robots remains a significant challenge due to lack of underwater geolocalization capabilities....Water is an essential component of the Earth’s climate,but monitoring its properties using autonomous underwater sampling robots remains a significant challenge due to lack of underwater geolocalization capabilities.Current methods for underwater geolocalization rely on tethered systems with limited coverage or daytime imagery data in clear waters,leaving much of the underwater environment unexplored.Geolocalization in turbid waters or at night has been considered unfeasible due to absence of identifiable landmarks.In this paper,we present a novel method for underwater geolocalization using deep neural networks trained on-10 million polarization-sensitive images acquired globally,along with camera position sensor data.Our approach achieves longitudinal accuracy of-55 km(-1000 km)during daytime(nighttime)at depths up to-8 m,regardless of water turbidity.In clear waters,the transfer learning longitudinal accuracy is-255 km at 50 m depth.By leveraging optical data in conjunction with camera position information,our novel method facilitates underwater geolocalization and offers a valuable tool for untethered underwater navigation.展开更多
Tracking and mating data of Common Terns(Sterna hirundo)breeding in a single colony in north-eastern Germany were used to test for assortative mating in regards to migratory phenotypes.These birds use the eastern and ...Tracking and mating data of Common Terns(Sterna hirundo)breeding in a single colony in north-eastern Germany were used to test for assortative mating in regards to migratory phenotypes.These birds use the eastern and western African migration routes and three different wintering areas along the African coast.However,no assortative mating was found for either migratory route or wintering area,as birds using both flyways and all three wintering areas paired randomly,which might be explained by a lack of difference in the arrival date at the colony between the groups.These results might indicate a low degree of genetic fixation of migratory route and wintering area in the Common Tern,which might hint that migratory direction and wintering sites could be passed to young terns via social learning,either by joining the parents or migratory flocks of conspecifics.If migratory phenotypes are passed on by a parent,it seems more likely that it is passed from father to young,as female Common Terns tend to leave the colony earlier and males provide the majority of post-fledging care.展开更多
The geolocation of ground targets by airborne image sensors is an important task for unmanned aerial vehicles or surveillance aircraft.This paper proposes an Iterative Geolocation based on Cross-view Image Registratio...The geolocation of ground targets by airborne image sensors is an important task for unmanned aerial vehicles or surveillance aircraft.This paper proposes an Iterative Geolocation based on Cross-view Image Registration(IGCIR)that can provide real-time target location results with high precision.The proposed method has two key features.First,a cross-view image registration process is introduced,including a projective transformation and a two-stage multi-sensor registration.This process utilizes both gradient information and phase information of cross-view images.This allows the registration process to reach a good balance between matching precision and computational efficiency.By matching the airborne camera view to the preloaded digital map,the geolocation accuracy can reach the accuracy level of the digital map for any ground target appearing in the airborne camera view.Second,the proposed method uses the registration results to perform an iteration process,which compensates for the bias of the strap-down initial navigation module online.Although it is challenging to provide cross-view registration results with high frequency,such an iteration process allows the method to generate real-time,highly accurate location results.The effectiveness of the proposed IGCIR method is verified by a series of flying-test experiments.The results show that the location accuracy of the method can reach 4.18 m(at 10 km standoff distance).展开更多
In this paper,the latest progress,major achievements and future plans of Chinese meteorological satellites and the core data processing techniques are discussed.First,the latest three FengYun(FY)meteorological satelli...In this paper,the latest progress,major achievements and future plans of Chinese meteorological satellites and the core data processing techniques are discussed.First,the latest three FengYun(FY)meteorological satellites(FY-2H,FY-3D,and FY-4A)and their primary objectives are introduced Second,the core image navigation techniques and accuracies of the FY meteorological satellites are elaborated,including the latest geostationary(FY-2/4)and polar-orbit(FY-3)satellites.Third,the radiometric calibration techniques and accuracies of reflective solar bands,thermal infrared bands,and passive microwave bands for FY meteorological satellites are discussed.It also illustrates the latest progress of real-time calibration with the onboard calibration system and validation with different methods,including the vicarious China radiance calibration site calibration,pseudo invariant calibration site calibration,deep convective clouds calibration,and lunar calibration.Fourth,recent progress of meteorological satellite data assimilation applications and quantitative science produce are summarized at length.The main progress is in meteorological satellite data assimilation by using microwave and hyper-spectral infrared sensors in global and regional numerical weather prediction models.Lastly,the latest progress in radiative transfer,absorption and scattering calculations for satellite remote sensing is summarized,and some important research using a new radiative transfer model are illustrated.展开更多
TerraSAR-X(TSX)can acquire high-resolution SAR images and due to its high orbit precision as well as its ability to acquire data from different off-nadir viewing angles,the high-precision stereo geolocation can be obt...TerraSAR-X(TSX)can acquire high-resolution SAR images and due to its high orbit precision as well as its ability to acquire data from different off-nadir viewing angles,the high-precision stereo geolocation can be obtained.In this study,we investigate the absolute geolocation accuracy of TSX high-resolution images in Wuhan,China.We present a direct stereo SAR geolocation method and analyze the 2D and 3D geoposition accuracy of two corner reflectors.The sub-meter localization accuracy was achieved using only atmospheric correction information available in the TSX metadata.展开更多
Although many classical IP geolocation algorithms are suitable to rich-connected networks, their performances are seriously affected in poor-connected networks with weak delay-distance correlation. This paper tries to...Although many classical IP geolocation algorithms are suitable to rich-connected networks, their performances are seriously affected in poor-connected networks with weak delay-distance correlation. This paper tries to improve the performances of classical IP geolocation algorithms by finding rich-connected sub-networks inside poor-connected networks. First, a new delay-distance correlation model （RTD-Corr model） is proposed. It builds the relationship between delay-distance correlation and actual network factors such as the tortuosity of the network path and the ratio of propagation delay. Second, based on the RTD-Corr model and actual network characteristics, this paper discusses about how to find rich-connected networks inside China Intemet which is a typical actual poor-connected network. Then we find rich-connected sub-networks of China Intemet through a large-scale network measurement which covers three major ISPs and thirty provinces. At last, based on the founded rich-connected sub-networks, we modify two classical IP geolocation algorithms and the experiments in China Intemet show that their accuracy is significantly increased.展开更多
High-density street-level reliable landmarks are one of the important foundations for street-level geolocation.However,the existing methods cannot obtain enough street-level landmarks in a short period of time.In this...High-density street-level reliable landmarks are one of the important foundations for street-level geolocation.However,the existing methods cannot obtain enough street-level landmarks in a short period of time.In this paper,a street-level landmarks acquisition method based on SVM(Support Vector Machine)classifiers is proposed.Firstly,the port detection results of IPs with known services are vectorized,and the vectorization results are used as an input of the SVM training.Then,the kernel function and penalty factor are adjusted for SVM classifiers training,and the optimal SVM classifiers are obtained.After that,the classifier sequence is constructed,and the IPs with unknown service are classified using the sequence.Finally,according to the domain name corresponding to the IP,the relationship between the classified server IP and organization name is established.The experimental results in Guangzhou and Wuhan city in China show that the proposed method can be as a supplement to existing typical methods since the number of obtained street-level landmarks is increased substantially,and the median geolocation error using evaluated landmarks is reduced by about 2 km.展开更多
An increasing trend in use of tracking devices such as geolocators is based on the assumption that the information gathered from such devices provides reliable information about the migratory behavior of free-living b...An increasing trend in use of tracking devices such as geolocators is based on the assumption that the information gathered from such devices provides reliable information about the migratory behavior of free-living birds. This underlying as- sumption is rarely tested, as evidenced by the absence in many studies of controls, in particular treated controls, and so far never with a reasonable statistical power. Published studies have shown reduced survival prospects or delayed breeding in some species, suggesting that there may be reason to doubt that tracking devices provide unbiased information. Therefore, we conducted a meta-analysis of studies applying geolocators to wild birds to determine whether geolocators affected fitness components. Ge- olocators had an overall negative effect on fitness components, in particular survival, and ecological variables. Effect size was larger for aerial foragers than for other species. Moreover the leg band attachment method was more detrimental for birds than the leg-loop backpack harness. A meta-regression model of effect size showed independent negative effects of geolocators on ae- rial foragers, smaller species, species with smaller migration distances and in studies where geolocators were attached with a ring. These results suggest that geolocator studies should be interpreted with caution, but also raise questions whether it is ethically defensible to use geolocators on aerial foragers or small species without carrying out robust pilot studies.展开更多
One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in specie...One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in species that cross such barriers, and are thought to have evolved in response to seasonal variation in prevailing wind direction. We tested the hypothesis that migration routes vary seasonally with respect to the Gulf of Mexico in the tree swallow Tachycineta bicolor using solar geolocators attached and retrieved at 4 breeding sites in central North America. We found that 100 % of birds （n = 10） made a trans-Gulf flight of 〉850 km from Louisiana south to their wintering grounds in the Yucatan Peninsula in 12-36 hours, achieving minimum ground speeds as high as 32 m/s. Although most days during autumn migration were characterized by unfavorable headwinds blowing to the northwest, migration over the Gulf mostly occurred on days with strong winds blowing to the south. In contrast, in 8 of 9 （88 %） birds on spring migration returned from the wintering grounds towards Louisiana following a clockwise loop pat- tern flying over land to the west around the Gulf. During this spring period there were few days with prevailing winds from the south to assist northward migration. Results suggest that, despite being up to three times further （ca. 2,700 kin）, a coastal circum-Gulf spring migration represents the less risky route when wind conditions are not favorable. These findings also help to resolve a long-standing dispute in the literature concerning migration patterns between the US Gulf coast and Mexico, and provide insight into the factors shaping migration strategies of small songbirds migrating across large bodies of water [Current Zoology 60（5）： 653-559, 2014].展开更多
Existing IP geolocation algorithms based on delay similarity often rely on the principle that geographically adjacent IPs have similar delays.However,this principle is often invalid in real Internet environment,which ...Existing IP geolocation algorithms based on delay similarity often rely on the principle that geographically adjacent IPs have similar delays.However,this principle is often invalid in real Internet environment,which leads to unreliable geolocation results.To improve the accuracy and reliability of locating IP in real Internet,a street-level IP geolocation algorithm based on landmarks clustering is proposed.Firstly,we use the probes to measure the known landmarks to obtain their delay vectors,and cluster landmarks using them.Secondly,the landmarks are clustered again by their latitude and longitude,and the intersection of these two clustering results is taken to form training sets.Thirdly,we train multiple neural networks to get the mapping relationship between delay and location in each training set.Finally,we determine one of the neural networks for the target by the delay similarity and relative hop counts,and then geolocate the target by this network.As it brings together the delay and geographical coordinates clustering,the proposed algorithm largely improves the inconsistency between them and enhances the mapping relationship between them.We evaluate the algorithm by a series of experiments in Hong Kong,Shanghai,Zhengzhou and New York.The experimental results show that the proposed algorithm achieves street-level IP geolocation,and comparing with existing typical streetlevel geolocation algorithms,the proposed algorithm improves the geolocation reliability significantly.展开更多
Range-Doppler (RD) method and Reverse-Range-Doppler (RRD) method are combined together to achieve automatic geocoding of Synthetic Aperture Radar (SAR) image quickly and accurately in the paper. The RD method is first...Range-Doppler (RD) method and Reverse-Range-Doppler (RRD) method are combined together to achieve automatic geocoding of Synthetic Aperture Radar (SAR) image quickly and accurately in the paper. The RD method is firstly used to locate the four corners of the image, then the other pixels of the image can be located by Reverse-Range-Doppler (RRD) method. Resampling is performed at last. The approach has an advantage over previous techniques in that it does not require ground control points and is independent of spacecraft attitude knowledge or control. It can compensate the shift due to the assumed Doppler frequency in SAR image preprocessing. RRD simplifies the process of RD, therefore speeds up the computation. The experimental results show that a SAR image can be automated geocoded in 30 s using the single CPU (3 GHz) with 1 G memory and an accuracy of 10 m is attainable with this method.展开更多
The Beijing Swift(Apus apus pekinensis)is a typical cavity-nesting bird that often nests inside holes and crevices in old architectures.Direct observation of their breeding behaviour is challenging and their breeding ...The Beijing Swift(Apus apus pekinensis)is a typical cavity-nesting bird that often nests inside holes and crevices in old architectures.Direct observation of their breeding behaviour is challenging and their breeding ecology is thus poorly studied.In this study,we analysed light-level geolocation data collected from six Beijing Swifts for the first time.Our results showed that geolocators can make comprehensive inference of their incubation period and behaviour.As a cost-effective and non-invasive method,geolocators can not only facilitate discovering migration routes,but also can be widely applied in the study of avian reproductive behaviour,especially in cavity-nesting bird species.We further discussed the characteristics and merits of this method and compared with other conventional nest-monitoring methods in recording birds.展开更多
基金financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior-Brasil(CAPES)(88887.929508/2023-00 and 88887.937224/2024-00)partially funded by the National Research Council of Brazil(CNPq)(307525/2022-8).
文摘Geolocalization is a crucial process that leverages environmental information and contextual data to accurately identify a position.In particular,cross-view geolocalization utilizes images from various perspectives,such as satellite and ground-level images,which are relevant for applications like robotics navigation and autonomous navigation.In this research,we propose a methodology that integrates cross-view geolocalization estimation with a land cover semantic segmentation map.Our solution demonstrates comparable performance to state-of-the-art methods,exhibiting enhanced stability and consistency regardless of the street view location or the dataset used.Additionally,our method generates a focused discrete probability distribution that acts as a heatmap.This heatmap effectively filters out incorrect and unlikely regions,enhancing the reliability of our estimations.Code is available at https://github.com/nathanxavier/CVSegGuide.
基金funded by grants from the Office of Naval Research(N00014-19-1-2400 and N00014-21-1-2177)U.S.Air Force Office of Scientific Research(FA9550-18-1-0278).
文摘Water is an essential component of the Earth’s climate,but monitoring its properties using autonomous underwater sampling robots remains a significant challenge due to lack of underwater geolocalization capabilities.Current methods for underwater geolocalization rely on tethered systems with limited coverage or daytime imagery data in clear waters,leaving much of the underwater environment unexplored.Geolocalization in turbid waters or at night has been considered unfeasible due to absence of identifiable landmarks.In this paper,we present a novel method for underwater geolocalization using deep neural networks trained on-10 million polarization-sensitive images acquired globally,along with camera position sensor data.Our approach achieves longitudinal accuracy of-55 km(-1000 km)during daytime(nighttime)at depths up to-8 m,regardless of water turbidity.In clear waters,the transfer learning longitudinal accuracy is-255 km at 50 m depth.By leveraging optical data in conjunction with camera position information,our novel method facilitates underwater geolocalization and offers a valuable tool for untethered underwater navigation.
基金the Landesamt für Umwelt,Naturschutz und Geologie Mecklenburg-Vorpommern(LUNG M-V)the Orthop?die+Vital Zentrum Piro GmbH+2 种基金the Institut für Vogelforschung“Vogelwarte Helgoland”(IfV)the German Ornithologists’Society(DO-G,project“Migration behaviour of Western Pomeranian terns”)the University of Greifswald(“AG Vogelwarte”)。
文摘Tracking and mating data of Common Terns(Sterna hirundo)breeding in a single colony in north-eastern Germany were used to test for assortative mating in regards to migratory phenotypes.These birds use the eastern and western African migration routes and three different wintering areas along the African coast.However,no assortative mating was found for either migratory route or wintering area,as birds using both flyways and all three wintering areas paired randomly,which might be explained by a lack of difference in the arrival date at the colony between the groups.These results might indicate a low degree of genetic fixation of migratory route and wintering area in the Common Tern,which might hint that migratory direction and wintering sites could be passed to young terns via social learning,either by joining the parents or migratory flocks of conspecifics.If migratory phenotypes are passed on by a parent,it seems more likely that it is passed from father to young,as female Common Terns tend to leave the colony earlier and males provide the majority of post-fledging care.
基金supported by the National Level Project of China(No.52-L0D01-0613-20/22)。
文摘The geolocation of ground targets by airborne image sensors is an important task for unmanned aerial vehicles or surveillance aircraft.This paper proposes an Iterative Geolocation based on Cross-view Image Registration(IGCIR)that can provide real-time target location results with high precision.The proposed method has two key features.First,a cross-view image registration process is introduced,including a projective transformation and a two-stage multi-sensor registration.This process utilizes both gradient information and phase information of cross-view images.This allows the registration process to reach a good balance between matching precision and computational efficiency.By matching the airborne camera view to the preloaded digital map,the geolocation accuracy can reach the accuracy level of the digital map for any ground target appearing in the airborne camera view.Second,the proposed method uses the registration results to perform an iteration process,which compensates for the bias of the strap-down initial navigation module online.Although it is challenging to provide cross-view registration results with high frequency,such an iteration process allows the method to generate real-time,highly accurate location results.The effectiveness of the proposed IGCIR method is verified by a series of flying-test experiments.The results show that the location accuracy of the method can reach 4.18 m(at 10 km standoff distance).
基金funded by the National Key R&D Program of China(Grant Nos.2018YFB0504900 and 2015AA123700)
文摘In this paper,the latest progress,major achievements and future plans of Chinese meteorological satellites and the core data processing techniques are discussed.First,the latest three FengYun(FY)meteorological satellites(FY-2H,FY-3D,and FY-4A)and their primary objectives are introduced Second,the core image navigation techniques and accuracies of the FY meteorological satellites are elaborated,including the latest geostationary(FY-2/4)and polar-orbit(FY-3)satellites.Third,the radiometric calibration techniques and accuracies of reflective solar bands,thermal infrared bands,and passive microwave bands for FY meteorological satellites are discussed.It also illustrates the latest progress of real-time calibration with the onboard calibration system and validation with different methods,including the vicarious China radiance calibration site calibration,pseudo invariant calibration site calibration,deep convective clouds calibration,and lunar calibration.Fourth,recent progress of meteorological satellite data assimilation applications and quantitative science produce are summarized at length.The main progress is in meteorological satellite data assimilation by using microwave and hyper-spectral infrared sensors in global and regional numerical weather prediction models.Lastly,the latest progress in radiative transfer,absorption and scattering calculations for satellite remote sensing is summarized,and some important research using a new radiative transfer model are illustrated.
基金This work was supported by the National Natural Science Foundation of China[grant number 61331016]and[grant number 41174120].The TerraSAR-X data were provided by DLR via the LAN2245 Project.
文摘TerraSAR-X(TSX)can acquire high-resolution SAR images and due to its high orbit precision as well as its ability to acquire data from different off-nadir viewing angles,the high-precision stereo geolocation can be obtained.In this study,we investigate the absolute geolocation accuracy of TSX high-resolution images in Wuhan,China.We present a direct stereo SAR geolocation method and analyze the 2D and 3D geoposition accuracy of two corner reflectors.The sub-meter localization accuracy was achieved using only atmospheric correction information available in the TSX metadata.
基金Supported by the National Natural Science Foundation of China(61379151,61274189,61302159 and 61401512)the Excellent Youth Foundation of Henan Province of China(144100510001)Foundation of Science and Technology on Information Assurance Laboratory(KJ-14-108)
文摘Although many classical IP geolocation algorithms are suitable to rich-connected networks, their performances are seriously affected in poor-connected networks with weak delay-distance correlation. This paper tries to improve the performances of classical IP geolocation algorithms by finding rich-connected sub-networks inside poor-connected networks. First, a new delay-distance correlation model （RTD-Corr model） is proposed. It builds the relationship between delay-distance correlation and actual network factors such as the tortuosity of the network path and the ratio of propagation delay. Second, based on the RTD-Corr model and actual network characteristics, this paper discusses about how to find rich-connected networks inside China Intemet which is a typical actual poor-connected network. Then we find rich-connected sub-networks of China Intemet through a large-scale network measurement which covers three major ISPs and thirty provinces. At last, based on the founded rich-connected sub-networks, we modify two classical IP geolocation algorithms and the experiments in China Intemet show that their accuracy is significantly increased.
基金The work presented in this paper is supported by the National Key R&D Program of China[Nos.2016YFB0801303,2016QY01W0105]the National Natural Science Foundation of China[Nos.U1636219,U1804263,61602508,61772549,U1736214,61572052]Plan for Scientific Innovation Talent of Henan Province[No.2018JR0018].
文摘High-density street-level reliable landmarks are one of the important foundations for street-level geolocation.However,the existing methods cannot obtain enough street-level landmarks in a short period of time.In this paper,a street-level landmarks acquisition method based on SVM(Support Vector Machine)classifiers is proposed.Firstly,the port detection results of IPs with known services are vectorized,and the vectorization results are used as an input of the SVM training.Then,the kernel function and penalty factor are adjusted for SVM classifiers training,and the optimal SVM classifiers are obtained.After that,the classifier sequence is constructed,and the IPs with unknown service are classified using the sequence.Finally,according to the domain name corresponding to the IP,the relationship between the classified server IP and organization name is established.The experimental results in Guangzhou and Wuhan city in China show that the proposed method can be as a supplement to existing typical methods since the number of obtained street-level landmarks is increased substantially,and the median geolocation error using evaluated landmarks is reduced by about 2 km.
文摘An increasing trend in use of tracking devices such as geolocators is based on the assumption that the information gathered from such devices provides reliable information about the migratory behavior of free-living birds. This underlying as- sumption is rarely tested, as evidenced by the absence in many studies of controls, in particular treated controls, and so far never with a reasonable statistical power. Published studies have shown reduced survival prospects or delayed breeding in some species, suggesting that there may be reason to doubt that tracking devices provide unbiased information. Therefore, we conducted a meta-analysis of studies applying geolocators to wild birds to determine whether geolocators affected fitness components. Ge- olocators had an overall negative effect on fitness components, in particular survival, and ecological variables. Effect size was larger for aerial foragers than for other species. Moreover the leg band attachment method was more detrimental for birds than the leg-loop backpack harness. A meta-regression model of effect size showed independent negative effects of geolocators on ae- rial foragers, smaller species, species with smaller migration distances and in studies where geolocators were attached with a ring. These results suggest that geolocator studies should be interpreted with caution, but also raise questions whether it is ethically defensible to use geolocators on aerial foragers or small species without carrying out robust pilot studies.
文摘One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in species that cross such barriers, and are thought to have evolved in response to seasonal variation in prevailing wind direction. We tested the hypothesis that migration routes vary seasonally with respect to the Gulf of Mexico in the tree swallow Tachycineta bicolor using solar geolocators attached and retrieved at 4 breeding sites in central North America. We found that 100 % of birds （n = 10） made a trans-Gulf flight of 〉850 km from Louisiana south to their wintering grounds in the Yucatan Peninsula in 12-36 hours, achieving minimum ground speeds as high as 32 m/s. Although most days during autumn migration were characterized by unfavorable headwinds blowing to the northwest, migration over the Gulf mostly occurred on days with strong winds blowing to the south. In contrast, in 8 of 9 （88 %） birds on spring migration returned from the wintering grounds towards Louisiana following a clockwise loop pat- tern flying over land to the west around the Gulf. During this spring period there were few days with prevailing winds from the south to assist northward migration. Results suggest that, despite being up to three times further （ca. 2,700 kin）, a coastal circum-Gulf spring migration represents the less risky route when wind conditions are not favorable. These findings also help to resolve a long-standing dispute in the literature concerning migration patterns between the US Gulf coast and Mexico, and provide insight into the factors shaping migration strategies of small songbirds migrating across large bodies of water [Current Zoology 60（5）： 653-559, 2014].
基金the National Key R&D Program of China 2016YFB0801303(F.L.received the grant,the sponsors’website is https://service.most.gov.cn/)by the National Key R&D Program of China 2016QY01W0105(X.L.received the grant,the sponsors’website is https://service.most.gov.cn/)+5 种基金by the National Natural Science Foundation of China U1636219(X.L.received the grant,the sponsors’website is http://www.nsfc.gov.cn/)by the National Natural Science Foundation of China 61602508(J.L.received the grant,the sponsors’website is http://www.nsfc.gov.cn/)by the National Natural Science Foundation of China 61772549(F.L.received the grant,the sponsors’website is http://www.nsfc.gov.cn/)by the National Natural Science Foundation of China U1736214(F.L.received the grant,the sponsors’website is http://www.nsfc.gov.cn/)by the National Natural Science Foundation of China U1804263(X.L.received the grant,the sponsors’website is http://www.nsfc.gov.cn/)by the Science and Technology Innovation Talent Project of Henan Province 184200510018(X.L.received the grant,the sponsors’website is http://www.hnkjt.gov.cn/).
文摘Existing IP geolocation algorithms based on delay similarity often rely on the principle that geographically adjacent IPs have similar delays.However,this principle is often invalid in real Internet environment,which leads to unreliable geolocation results.To improve the accuracy and reliability of locating IP in real Internet,a street-level IP geolocation algorithm based on landmarks clustering is proposed.Firstly,we use the probes to measure the known landmarks to obtain their delay vectors,and cluster landmarks using them.Secondly,the landmarks are clustered again by their latitude and longitude,and the intersection of these two clustering results is taken to form training sets.Thirdly,we train multiple neural networks to get the mapping relationship between delay and location in each training set.Finally,we determine one of the neural networks for the target by the delay similarity and relative hop counts,and then geolocate the target by this network.As it brings together the delay and geographical coordinates clustering,the proposed algorithm largely improves the inconsistency between them and enhances the mapping relationship between them.We evaluate the algorithm by a series of experiments in Hong Kong,Shanghai,Zhengzhou and New York.The experimental results show that the proposed algorithm achieves street-level IP geolocation,and comparing with existing typical streetlevel geolocation algorithms,the proposed algorithm improves the geolocation reliability significantly.
文摘Range-Doppler (RD) method and Reverse-Range-Doppler (RRD) method are combined together to achieve automatic geocoding of Synthetic Aperture Radar (SAR) image quickly and accurately in the paper. The RD method is firstly used to locate the four corners of the image, then the other pixels of the image can be located by Reverse-Range-Doppler (RRD) method. Resampling is performed at last. The approach has an advantage over previous techniques in that it does not require ground control points and is independent of spacecraft attitude knowledge or control. It can compensate the shift due to the assumed Doppler frequency in SAR image preprocessing. RRD simplifies the process of RD, therefore speeds up the computation. The experimental results show that a SAR image can be automated geocoded in 30 s using the single CPU (3 GHz) with 1 G memory and an accuracy of 10 m is attainable with this method.
基金funded by SHAN SHUI Conservation Centre,Beijing。
文摘The Beijing Swift(Apus apus pekinensis)is a typical cavity-nesting bird that often nests inside holes and crevices in old architectures.Direct observation of their breeding behaviour is challenging and their breeding ecology is thus poorly studied.In this study,we analysed light-level geolocation data collected from six Beijing Swifts for the first time.Our results showed that geolocators can make comprehensive inference of their incubation period and behaviour.As a cost-effective and non-invasive method,geolocators can not only facilitate discovering migration routes,but also can be widely applied in the study of avian reproductive behaviour,especially in cavity-nesting bird species.We further discussed the characteristics and merits of this method and compared with other conventional nest-monitoring methods in recording birds.
