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
Geolocating social media users aims to discover the real geographical locations of users from their publicly available data,which can support online location-based applications such as disaster alerts and local conten...Geolocating social media users aims to discover the real geographical locations of users from their publicly available data,which can support online location-based applications such as disaster alerts and local content recommen-dations.Social relationship-based methods represent a classical approach for geolocating social media.However,geographically proximate relationships are sparse and challenging to discern within social networks,thereby affecting the accuracy of user geolocation.To address this challenge,we propose user geolocation methods that integrate neighborhood geographical distribution and social structure influence(NGSI)to improve geolocation accuracy.Firstly,we propose a method for evaluating the homophily of locations based on the k-order neighbor-hood geographic distribution(k-NGD)similarity among users.There are notable differences in the distribution of k-NGD similarity between location-proximate and non-location-proximate users.Exploiting this distinction,we filter out non-location-proximate social relationships to enhance location homophily in the social network.To better utilize the location-proximate relationships in social networks,we propose a graph neural network algorithm based on the social structure influence.The algorithm enables us to perform a weighted aggregation of the information of users’multi-hop neighborhood,thereby mitigating the over-smoothing problem of user features and improving user geolocation performance.Experimental results on real social media dataset demonstrate that the neighborhood geographical distribution similarity metric can effectively filter out non-location-proximate social relationships.Moreover,compared with 7 existing social relationship-based user positioning methods,our proposed method can achieve multi-granularity user geolocation and improve the accuracy by 4.84%to 13.28%.展开更多
Stereo synthetic aperture radar （SAR） geolocation model is an important geolocation model for spaceborne SAR. However, the error of stereo SAR geolocation model has not been analyzed in detail. This paper deduced th...Stereo synthetic aperture radar （SAR） geolocation model is an important geolocation model for spaceborne SAR. However, the error of stereo SAR geolocation model has not been analyzed in detail. This paper deduced the geolocation error formulas of the stereo SAR geolocation model and then compared the geolocation error with range Doppler （RD） geolocation model. Through computer simulation, we could get the advantages and disadvantages of the stereo SAR geolocation model.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
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
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
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
For the high-resolution airborne synthetic aperture radar （SAR） stereo geolocation application, the final geolocation ac- curacy is influenced by various error parameter sources. In this paper, an airborne SAR stere...For the high-resolution airborne synthetic aperture radar （SAR） stereo geolocation application, the final geolocation ac- curacy is influenced by various error parameter sources. In this paper, an airborne SAR stereo geolocation parameter error model, involving the parameter errors derived from the navigation system on the flight platform, has been put forward. Moreover, a kind of near-direct method for modeling and sensitivity analysis of navigation parameter errors is also given. This method directly uses the ground reference to calculate the covariance matrix relationship between the parameter errors and the eventual geoloeation errors for ground target points. In addition, utilizing true flight track parameters＇ errors, this paper gave a verification of the method and a corresponding sensitivity analysis for airborne SAR stereo geolocation model and proved its efficiency.展开更多
A novel statistical angle-of-arrival (AOA) model for indoor geolocation applications is presented. The modeling approach focuses on the arrivals of the multipath components with respect to the line-of-sight (LOS) path...A novel statistical angle-of-arrival (AOA) model for indoor geolocation applications is presented. The modeling approach focuses on the arrivals of the multipath components with respect to the line-of-sight (LOS) path which is an important component especially when indoor geolocation applications are considered. The model is particularly important for indoor applications where AOA information could be utilized for tracking indirect paths to aid in precise ranging in harsh and dense multipath environments where LOS path might be blocked due to obstructions. The results have been obtained by a measurement calibrated ray-tracing (RT) tool.展开更多
Soil forensics is most commonly used to test an association between soils at a known location with soils recovered from exhibits recovered from a suspect.This type of comparative analysis is now a routine technique in...Soil forensics is most commonly used to test an association between soils at a known location with soils recovered from exhibits recovered from a suspect.This type of comparative analysis is now a routine technique in many laboratories world-wide.Soils are however,very complex materials made up of natural inorganic,organic and manmade components.The distribution and abundance of these components is generally controlled by a range of predictable factors,such as bedrock geology,surface processes,plant and animal biogeographical distributions and anthropogenic processes.As such,the composition of a soil can be used as a predictive tool to describe the nature of the location where that soil originated.This approach to soil forensics,termed predictive geolocation,has many applications in criminal,environmental and intelligence based investigations.展开更多
Monitoring and managing maize seedlings post-planting is essential for ensuring yield and quality.Unmanned aerial vehicle(UAV)remote sensing technology has been widely integrated for non-destructive detection of maize...Monitoring and managing maize seedlings post-planting is essential for ensuring yield and quality.Unmanned aerial vehicle(UAV)remote sensing technology has been widely integrated for non-destructive detection of maize seedlings.However,significant challenges remain in maize seedling monitoring,such as relatively late monitoring periods,high data annotation costs,and lack of geolocation feedback for missing seedlings.To tackle these issues,this study focused on maize seedlings up to and including the second vegetative leaf(V2)stage.Firstly,the detection performance of both seedlings and missing seedlings was evaluated using a fully labeled dataset,achieving a mean precision of 92.06%,recall of 87.44%,and AP50 of 91.23%.Then,the role of unlabeled data in enhancing the effectiveness of object detection was studied based on the efficient teacher semi-supervised learning framework.Significant improvements were observed when the labeled to unlabeled data ratio ranged from 1:2 to 1:12.The best results for mean precision,recall,and AP50 were improved by 2.69%,2.65%,and 2.35%,respectively.Additionally,an end-to-end pipeline was developed from image collection to seedling condition analysis,which effectively enhanced the detection of missing seedlings and accurately mapped them to geographical coordinates with an average deviation of 0.462m.This pipeline bridges the gap between missing seedling detection and replanting feedback,providing a feasible and precise detection solution for maize seedlings and supporting efficient field production management.展开更多
IP geolocation is essential for the territorial analysis of sensitive network entities,location-based services(LBS)and network fraud detection.It has important theoretical significance and application value.Measuremen...IP geolocation is essential for the territorial analysis of sensitive network entities,location-based services(LBS)and network fraud detection.It has important theoretical significance and application value.Measurement-based IP geolocation is a hot research topic.However,the existing IP geolocation algorithms cannot effectively utilize the distance characteristics of the delay,and the nodes’connection relation,resulting in high geolocation error.It is challenging to obtain the mapping between delay,nodes’connection relation,and geographical location.Based on the idea of network representation learning,we propose a representation learning model for IP nodes(IP2vec for short)and apply it to street-level IP geolocation.IP2vec model vectorizes nodes according to the connection relation and delay between nodes so that the IP vectors can reflect the distance and topological proximity between IP nodes.The steps of the street-level IP geolocation algorithm based on IP2vec model are as follows:Firstly,we measure landmarks and target IP to obtain delay and path information to construct the network topology.Secondly,we use the IP2vec model to obtain the IP vectors from the network topology.Thirdly,we train a neural network to fit the mapping relation between vectors and locations of landmarks.Finally,the vector of target IP is fed into the neural network to obtain the geographical location of target IP.The algorithm can accurately infer geographical locations of target IPs based on delay and topological proximity embedded in the IP vectors.The cross-validation experimental results on 10023 target IPs in New York,Beijing,Hong Kong,and Zhengzhou demonstrate that the proposed algorithm can achieve street-level geolocation.Compared with the existing algorithms such as Hop-Hot,IP-geolocater and SLG,the mean geolocation error of the proposed algorithm is reduced by 33%,39%,and 51%,respectively.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
Determining the position of an emitter on Earth by using a satellite cluster has many important applications, such as in navigation, surveillance, and remote sensing. However, in realistic situations, a number of fact...Determining the position of an emitter on Earth by using a satellite cluster has many important applications, such as in navigation, surveillance, and remote sensing. However, in realistic situations, a number of factors, such as errors in the measurement of signal parameters, uncertainties regarding the position of satellites, and errors in the location of calibration sources, are known to degrade the accuracy of target localization in satellite geolocation systems. We systematically analyze the performance of multi-satellite joint geolocation based on time difference of arrival （TDOA） measurements. The theoretical analysis starts with Cramer Rao bound （CRB） derivations for four localization scenarios under an altitude constraint and Gaussian noise assumption. In scenario 1, only the TDOA measurement errors of the emitting source are considered and the satellite positions are assumed to be perfectly estimated. In scenario 2, both the TDOA measurement errors and satellite position uncertainties are taken into account. Scenario 3 assumes that some calibration sources with accurate position information are used to mitigate the influence of satellite position perturbations. In scenario 4, several calibration sources at inaccurate locations are used to alleviate satellite position errors in target localization. Through comparing the CRBs of the four localization scenarios, some valuable＇s insights are gained into the effects of various error sources on the estimation performance. Two kinds of location mean-square errors （MSE） expressions under the altitude constraint are derived through first-order perturbation analysis and the Lagrange method. The first location MSE provides the theoretical prediction when an estimator assumes that the satellite locations are accurate but in fact have errors. The second location MSE provides the localization accuracy if an estimator assumes that the known calibration source locations are precise while in fact erroneous. Simulation results are included to verify the theoretical analysis.展开更多
Location based services(LBS)are widely utilized,and determining the location of users’IP is the foundation for LBS.Constrained by unstable delay and insufficient landmarks,the existing geolocation algorithms have pro...Location based services(LBS)are widely utilized,and determining the location of users’IP is the foundation for LBS.Constrained by unstable delay and insufficient landmarks,the existing geolocation algorithms have problems such as low geolocation accuracy and uncertain geolocation error,difficult to meet the requirements of LBS for accuracy and reliability.A new IP geolocation algorithm based on router error training is proposed in this manuscript to improve the accuracy of geolocation results and obtain the current geolocation error range.Firstly,bootstrapping is utilized to divide the landmark data into training set and verification set,and/24 subnet distribution is utilized to extend the training set.Secondly,the path detection is performed on nodes in the three data sets respectively to extract the metropolitan area network(MAN)of the target city,and the geolocation result and error of each router in MAN are obtained by training the detection results.Finally,the MAN is utilized to get the target’s location.Based on China’s 24,254 IP geolocation experiments,the proposed algorithm has higher geolocation accuracy and lower median error than existing typical geolocation algorithms LBG,SLG,NNG and RNBG,and in most cases the difference is less than 10km between estimated error and actual error.展开更多
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This work was supported by the National Key R&D Program of China(No.2022YFB3102904)the National Natural Science Foundation of China(No.62172435,U23A20305)Key Research and Development Project of Henan Province(No.221111321200).
文摘Geolocating social media users aims to discover the real geographical locations of users from their publicly available data,which can support online location-based applications such as disaster alerts and local content recommen-dations.Social relationship-based methods represent a classical approach for geolocating social media.However,geographically proximate relationships are sparse and challenging to discern within social networks,thereby affecting the accuracy of user geolocation.To address this challenge,we propose user geolocation methods that integrate neighborhood geographical distribution and social structure influence(NGSI)to improve geolocation accuracy.Firstly,we propose a method for evaluating the homophily of locations based on the k-order neighbor-hood geographic distribution(k-NGD)similarity among users.There are notable differences in the distribution of k-NGD similarity between location-proximate and non-location-proximate users.Exploiting this distinction,we filter out non-location-proximate social relationships to enhance location homophily in the social network.To better utilize the location-proximate relationships in social networks,we propose a graph neural network algorithm based on the social structure influence.The algorithm enables us to perform a weighted aggregation of the information of users’multi-hop neighborhood,thereby mitigating the over-smoothing problem of user features and improving user geolocation performance.Experimental results on real social media dataset demonstrate that the neighborhood geographical distribution similarity metric can effectively filter out non-location-proximate social relationships.Moreover,compared with 7 existing social relationship-based user positioning methods,our proposed method can achieve multi-granularity user geolocation and improve the accuracy by 4.84%to 13.28%.
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)the National Natural Science Foundation of China (Grant No.61071185)+1 种基金the Key Technology Research and Development Program of Science and Technology Commission of Shanghai Municipality (Grant No.10511501702)the Science and Technology Commission of Shanghai Municipality (Grant Nos.08590700500, 08DZ2231100)
文摘Stereo synthetic aperture radar （SAR） geolocation model is an important geolocation model for spaceborne SAR. However, the error of stereo SAR geolocation model has not been analyzed in detail. This paper deduced the geolocation error formulas of the stereo SAR geolocation model and then compared the geolocation error with range Doppler （RD） geolocation model. Through computer simulation, we could get the advantages and disadvantages of the stereo SAR geolocation model.
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.
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.
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.
基金Supported by the National Basic Research Program of China (No. 2006CB701303)
文摘For the high-resolution airborne synthetic aperture radar （SAR） stereo geolocation application, the final geolocation ac- curacy is influenced by various error parameter sources. In this paper, an airborne SAR stereo geolocation parameter error model, involving the parameter errors derived from the navigation system on the flight platform, has been put forward. Moreover, a kind of near-direct method for modeling and sensitivity analysis of navigation parameter errors is also given. This method directly uses the ground reference to calculate the covariance matrix relationship between the parameter errors and the eventual geoloeation errors for ground target points. In addition, utilizing true flight track parameters＇ errors, this paper gave a verification of the method and a corresponding sensitivity analysis for airborne SAR stereo geolocation model and proved its efficiency.
文摘A novel statistical angle-of-arrival (AOA) model for indoor geolocation applications is presented. The modeling approach focuses on the arrivals of the multipath components with respect to the line-of-sight (LOS) path which is an important component especially when indoor geolocation applications are considered. The model is particularly important for indoor applications where AOA information could be utilized for tracking indirect paths to aid in precise ranging in harsh and dense multipath environments where LOS path might be blocked due to obstructions. The results have been obtained by a measurement calibrated ray-tracing (RT) tool.
文摘Soil forensics is most commonly used to test an association between soils at a known location with soils recovered from exhibits recovered from a suspect.This type of comparative analysis is now a routine technique in many laboratories world-wide.Soils are however,very complex materials made up of natural inorganic,organic and manmade components.The distribution and abundance of these components is generally controlled by a range of predictable factors,such as bedrock geology,surface processes,plant and animal biogeographical distributions and anthropogenic processes.As such,the composition of a soil can be used as a predictive tool to describe the nature of the location where that soil originated.This approach to soil forensics,termed predictive geolocation,has many applications in criminal,environmental and intelligence based investigations.
基金supported by National Key R&D Program of China(2023YFD2000203)Science and Technology Department of Zhejiang Province(2022C02034).
文摘Monitoring and managing maize seedlings post-planting is essential for ensuring yield and quality.Unmanned aerial vehicle(UAV)remote sensing technology has been widely integrated for non-destructive detection of maize seedlings.However,significant challenges remain in maize seedling monitoring,such as relatively late monitoring periods,high data annotation costs,and lack of geolocation feedback for missing seedlings.To tackle these issues,this study focused on maize seedlings up to and including the second vegetative leaf(V2)stage.Firstly,the detection performance of both seedlings and missing seedlings was evaluated using a fully labeled dataset,achieving a mean precision of 92.06%,recall of 87.44%,and AP50 of 91.23%.Then,the role of unlabeled data in enhancing the effectiveness of object detection was studied based on the efficient teacher semi-supervised learning framework.Significant improvements were observed when the labeled to unlabeled data ratio ranged from 1:2 to 1:12.The best results for mean precision,recall,and AP50 were improved by 2.69%,2.65%,and 2.35%,respectively.Additionally,an end-to-end pipeline was developed from image collection to seedling condition analysis,which effectively enhanced the detection of missing seedlings and accurately mapped them to geographical coordinates with an average deviation of 0.462m.This pipeline bridges the gap between missing seedling detection and replanting feedback,providing a feasible and precise detection solution for maize seedlings and supporting efficient field production management.
基金the National Natural Science Foundation of China(Grant Nos.U1804263,U1736214,62172435)the Zhongyuan Science and Technology Innovation Leading Talent Project(No.214200510019)。
文摘IP geolocation is essential for the territorial analysis of sensitive network entities,location-based services(LBS)and network fraud detection.It has important theoretical significance and application value.Measurement-based IP geolocation is a hot research topic.However,the existing IP geolocation algorithms cannot effectively utilize the distance characteristics of the delay,and the nodes’connection relation,resulting in high geolocation error.It is challenging to obtain the mapping between delay,nodes’connection relation,and geographical location.Based on the idea of network representation learning,we propose a representation learning model for IP nodes(IP2vec for short)and apply it to street-level IP geolocation.IP2vec model vectorizes nodes according to the connection relation and delay between nodes so that the IP vectors can reflect the distance and topological proximity between IP nodes.The steps of the street-level IP geolocation algorithm based on IP2vec model are as follows:Firstly,we measure landmarks and target IP to obtain delay and path information to construct the network topology.Secondly,we use the IP2vec model to obtain the IP vectors from the network topology.Thirdly,we train a neural network to fit the mapping relation between vectors and locations of landmarks.Finally,the vector of target IP is fed into the neural network to obtain the geographical location of target IP.The algorithm can accurately infer geographical locations of target IPs based on delay and topological proximity embedded in the IP vectors.The cross-validation experimental results on 10023 target IPs in New York,Beijing,Hong Kong,and Zhengzhou demonstrate that the proposed algorithm can achieve street-level geolocation.Compared with the existing algorithms such as Hop-Hot,IP-geolocater and SLG,the mean geolocation error of the proposed algorithm is reduced by 33%,39%,and 51%,respectively.
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Project supported by the National Natural Science Foundation of China （No. 61201381）, the Future Development Foundation of Zhengzhou Information Science and Technology Institute （No. YPI2JJ202057）, China Postdoctoral Science Foundation （No. 2016M592989）, and the Outstanding Youth Foundation of Information Engineering University （No. 2016603201）
文摘Determining the position of an emitter on Earth by using a satellite cluster has many important applications, such as in navigation, surveillance, and remote sensing. However, in realistic situations, a number of factors, such as errors in the measurement of signal parameters, uncertainties regarding the position of satellites, and errors in the location of calibration sources, are known to degrade the accuracy of target localization in satellite geolocation systems. We systematically analyze the performance of multi-satellite joint geolocation based on time difference of arrival （TDOA） measurements. The theoretical analysis starts with Cramer Rao bound （CRB） derivations for four localization scenarios under an altitude constraint and Gaussian noise assumption. In scenario 1, only the TDOA measurement errors of the emitting source are considered and the satellite positions are assumed to be perfectly estimated. In scenario 2, both the TDOA measurement errors and satellite position uncertainties are taken into account. Scenario 3 assumes that some calibration sources with accurate position information are used to mitigate the influence of satellite position perturbations. In scenario 4, several calibration sources at inaccurate locations are used to alleviate satellite position errors in target localization. Through comparing the CRBs of the four localization scenarios, some valuable＇s insights are gained into the effects of various error sources on the estimation performance. Two kinds of location mean-square errors （MSE） expressions under the altitude constraint are derived through first-order perturbation analysis and the Lagrange method. The first location MSE provides the theoretical prediction when an estimator assumes that the satellite locations are accurate but in fact have errors. The second location MSE provides the localization accuracy if an estimator assumes that the known calibration source locations are precise while in fact erroneous. Simulation results are included to verify the theoretical analysis.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.U1804263,U1636219)the Science and Technology Innovation Talent Project of Henan Province(184200510018)Zhongyuan Science and Technology Innovation Leading Talent Project(214200510019).
文摘Location based services(LBS)are widely utilized,and determining the location of users’IP is the foundation for LBS.Constrained by unstable delay and insufficient landmarks,the existing geolocation algorithms have problems such as low geolocation accuracy and uncertain geolocation error,difficult to meet the requirements of LBS for accuracy and reliability.A new IP geolocation algorithm based on router error training is proposed in this manuscript to improve the accuracy of geolocation results and obtain the current geolocation error range.Firstly,bootstrapping is utilized to divide the landmark data into training set and verification set,and/24 subnet distribution is utilized to extend the training set.Secondly,the path detection is performed on nodes in the three data sets respectively to extract the metropolitan area network(MAN)of the target city,and the geolocation result and error of each router in MAN are obtained by training the detection results.Finally,the MAN is utilized to get the target’s location.Based on China’s 24,254 IP geolocation experiments,the proposed algorithm has higher geolocation accuracy and lower median error than existing typical geolocation algorithms LBG,SLG,NNG and RNBG,and in most cases the difference is less than 10km between estimated error and actual error.
