In the metric-based meta-learning detection model,the distribution of training samples in the metric space has great influence on the detection performance,and this influence is usually ignored by traditional meta-det...In the metric-based meta-learning detection model,the distribution of training samples in the metric space has great influence on the detection performance,and this influence is usually ignored by traditional meta-detectors.In addition,the design of metric space might be interfered with by the background noise of training samples.To tackle these issues,we propose a metric space optimisation method based on hyperbolic geometry attention and class-agnostic activation maps.First,the geometric properties of hyperbolic spaces to establish a structured metric space are used.A variety of feature samples of different classes are embedded into the hyperbolic space with extremely low distortion.This metric space is more suitable for representing tree-like structures between categories for image scene analysis.Meanwhile,a novel similarity measure function based on Poincarédistance is proposed to evaluate the distance of various types of objects in the feature space.In addition,the class-agnostic activation maps(CCAMs)are employed to re-calibrate the weight of foreground feature information and suppress background information.Finally,the decoder processes the high-level feature information as the decoding of the query object and detects objects by predicting their locations and corresponding task encodings.Experimental evaluation is conducted on Pascal VOC and MS COCO datasets.The experiment results show that the effectiveness of the authors’method surpasses the performance baseline of the excellent few-shot detection models.展开更多
Urban open spaces(UOS)play a crucial role in enhancing city livability and resident well-being,yet there remains a gap in utilizing social media to analyze changes in UOS utilization across different COVID(Corona Viru...Urban open spaces(UOS)play a crucial role in enhancing city livability and resident well-being,yet there remains a gap in utilizing social media to analyze changes in UOS utilization across different COVID(Corona Virus Disease)-19 phases.Our research applied Sina Weibo data to scrutinize UOS engagement across pre-pandemic(2019),pandemic(2021),and post-pandemic(2023)periods in Lanzhou City,China,revealing evolving spatiotemporal patterns and highlighting the pandemic's impact on UOS usage.Initially,scenic mountains and urban parks dominated visitor preferences in 2019.However,during the pandemic,there was a trend towards destinations that combined elements of tourism,business,entertainment,and culture,reflecting a growing appetite for diverse experiences.Despite this shift,the post-pandemic period did not see a complete return to pre-pandemic travel patterns,with a noticeable decline in visits to traditional green open spaces during lockdowns.We identified key attractions in main urban areas,highlighting geographical variations in tourism and Cultural Ecosystem Services(CES)distribution that warrant further attention.The post-pandemic landscape reveals a resurging interest in green-blue spaces and nature-focused tourism,highlighting a continued preference for cultural and natural experiences,and emphasizing the need to harmonize development with the preservation of natural and cultural heritage.This study introduces the use of social media data across pandemic phases to guide UOS management,offering insights for creating resilient,multifunctional urban spaces that address public needs and enhance community well-being.展开更多
This paper deals with the re-entry predictions of the space objects from the low eccentric orbit. Any re-entering object re-enters the Earth’s atmosphere with a high orbital velocity. Due to the aerodynamic heating t...This paper deals with the re-entry predictions of the space objects from the low eccentric orbit. Any re-entering object re-enters the Earth’s atmosphere with a high orbital velocity. Due to the aerodynamic heating the object tends to break into multiple fragments which later pose a great risk hazard to the population. Here a satellite is considered as the space object for which the re-entry prediction is made. This prediction is made with a package where the trajectory path, the time of re-entry and the survival rate of the fragments is done. The prediction is done using DRAMA 2.0—ESA’s Debris Risk Assessment and Mitigation Analysis Tool suite, MATLAB and Numerical Prediction of Orbital Events software. The predicted re-entry time of OSIRIS 3U was found to be on 7th March 2019, 7:25 (UTC), whereas the actual re-entry time was on 7th March 2019, 7:03 (UTC). The trajectory path found was 51.5699 deg. (Lat), −86.5738 deg. (Long.) with an altitude of 168.643 km. But the actual trajectory was 51.76 deg. (Lat), −89.01deg. (Long.) with an altitude of 143.5 km.展开更多
With the undergoing and planned implementations of mega constellations of thousands of Low Earth Orbiting(LEO)satellites,space will become even more congested for satellite operations.The enduring effects on the long-...With the undergoing and planned implementations of mega constellations of thousands of Low Earth Orbiting(LEO)satellites,space will become even more congested for satellite operations.The enduring effects on the long-term space environment have been investigated by various researchers using debris environment models.This paper is focused on the imminent short-term effects of LEO mega constellations on the space operation environment concerned by satellite owners and operators.The effects are measured in terms of the Close Approaches(CAs)and overall collision probability.Instead of using debris environment models,the CAs are determined from integrated orbit positions,and the collision probability is computed for each CA considering the sizes and position covariance of the involving objects.The obtained results thus present a clearer picture of the space operation safety environment when LEO mega constellations are deployed.Many mega constellations are simulated,including a Starlink-like constellation of 1584 satellites,four possible generic constellations at altitudes between 1110 km and 1325 km,and three constellations of 1584 satellites each at the altitudes of 650 km,800 km,and 950 km,respectively,where the Resident Space Object(RSO)spatial density is the highest.The increases in the number of CAs and overall collision probability caused by them are really alarming.The results suggest that highly frequent orbital maneuvers are required to avoid collisions between existing RSOs and constellation satellites,and between satellites from two constellations at a close altitude,as such the constellation operation burden would be very heavy.The study is not only useful for satellite operators but a powerful signal for various stakeholders to pay serious attention to the development of LEO mega constellations.展开更多
A soitable data model and data structure make underground survey objects maintained and operated easier. This paper gives a formal definition for underground survey objects. By making use of the quotient topological s...A soitable data model and data structure make underground survey objects maintained and operated easier. This paper gives a formal definition for underground survey objects. By making use of the quotient topological space, the author studies the logical relations among underground survey objects, a partiallyordered space uuder some conditions. An example is given to show the data model’s possible applications.展开更多
The application of high-performance imaging sensors in space-based space surveillance systems makes it possible to recognize space objects and estimate their poses using vision-based methods. In this paper, we propose...The application of high-performance imaging sensors in space-based space surveillance systems makes it possible to recognize space objects and estimate their poses using vision-based methods. In this paper, we proposed a kernel regression-based method for joint multi-view space object recognition and pose estimation. We built a new simulated satellite image dataset named BUAA-SID 1.5 to test our method using different image representations. We evaluated our method for recognition-only tasks, pose estimation-only tasks, and joint recognition and pose estimation tasks. Experimental results show that our method outperforms the state-of-the-arts in space object recognition, and can recognize space objects and estimate their poses effectively and robustly against noise and lighting conditions.展开更多
快速城市化加剧了社会发展与生态保护之间的矛盾,如何利用集约的资源要素实现社会-生态效益优化,是城市可持续发展的关键。以上海市中心城区为研究对象,基于多目标规划(multiple objective planning,MOP)模型设置效益目标函数和约束条...快速城市化加剧了社会发展与生态保护之间的矛盾,如何利用集约的资源要素实现社会-生态效益优化,是城市可持续发展的关键。以上海市中心城区为研究对象,基于多目标规划(multiple objective planning,MOP)模型设置效益目标函数和约束条件嵌入斑块生成土地利用变化模拟模型(patchgenerating land use simulation model,PLUS),实现多元目标下城市绿地生态网络多情景模拟及功能评价,以期为未来城市绿地生态网络高效构建、土地利用规划决策提供参考。结果表明:1)耦合MOP模型和PLUS模型,基于土地资源多效益目标的定量化求解,可以寻求社会-生态效益最优化的关键拐点;2)不同效益目标导向下,可持续发展情景较经济发展情景和生态保护情景,耕地、林地、水域等各用地类型的相互转化,以及经济发展和生态保护之间的关系均处于相对稳定状态;3)可持续发展情景的各项绿地生态网络测度指标均介于其他2个用地情景之间,重要斑块的数量及空间分布表征,在优化社会-生态效益、城市土地利用结构配置的同时,城市绿地生态网络功能也得到提升。研究成果为超大城市高密区绿地生态网络结构功能完善、土地利用规划科学决策、城市社会-生态系统综合效益提升提供科学参考。展开更多
A scheduling model of closely spaced parallel runways for arrival aircraft was proposed,with multi-objections of the minimum flight delay cost,the maximum airport capacity,the minimum workload of air traffic controlle...A scheduling model of closely spaced parallel runways for arrival aircraft was proposed,with multi-objections of the minimum flight delay cost,the maximum airport capacity,the minimum workload of air traffic controller and the maximum fairness of airlines′scheduling.The time interval between two runways and changes of aircraft landing order were taken as the constraints.Genetic algorithm was used to solve the model,and the model constrained unit delay cost of the aircraft with multiple flight tasks to reduce its delay influence range.Each objective function value or the fitness of particle unsatisfied the constrain condition would be punished.Finally,one domestic airport hub was introduced to verify the algorithm and the model.The results showed that the genetic algorithm presented strong convergence and timeliness for solving constraint multi-objective aircraft landing problem on closely spaced parallel runways,and the optimization results were better than that of actual scheduling.展开更多
As the number of space objects(SO)increases,collision avoidance problem in the rendezvous tasks or reconstellation of satellites with SO has been paid more attention,and the dangerous area of a possible collision shou...As the number of space objects(SO)increases,collision avoidance problem in the rendezvous tasks or reconstellation of satellites with SO has been paid more attention,and the dangerous area of a possible collision should be derived.In this paper,a maneuvering method is proposed for avoiding collision with a space debris object in the phasing orbit of the initial optimal solution.Accordingly,based on the plane of eccentricity vector components,relevant dangerous area which is bounded by two parallel lines is formulated.The axises of eccentricity vector system pass through the end of eccentricity vector of phasing orbit in the optimal solution,and orientation of axis depends on the latitude argument where a collision will occur.The dangerous area is represented especially with the graphical dialogue,and it allows to find a compromise between the SO avoiding and the fuel consumption reduction.The proposed method to solve the collision avoidance problem provides simplicity to calculate rendezvous maneuvers,and possibility to avoid collisions from several collisions or from“slow”collisions in a phasing orbit,when the protected spacecraft and the object fly dangerously close to each other for a long period.展开更多
This paper mainly focuses on the issues about generic multi-scale object perception for detection or recognition. A novel computational model in visually-feature space is presented for scene & object representatio...This paper mainly focuses on the issues about generic multi-scale object perception for detection or recognition. A novel computational model in visually-feature space is presented for scene & object representation to purse the underlying textural manifold statistically in nonparametric manner. The associative method approximately makes perceptual hierarchy in human-vision biologically coherency in specific quad-tree-pyramid structure, and the appropriate scale-value of different objects can automatically be selected by evaluating from well-defined scale function without any priori knowledge. The sufficient experiments truly demonstrate the effectiveness of scale determination in textural manifold with object localization rapidly.展开更多
Advancements in animal behavior quantification methods have driven the development of computational ethology,enabling fully automated behavior analysis.Existing multianimal pose estimation workflows rely on tracking-b...Advancements in animal behavior quantification methods have driven the development of computational ethology,enabling fully automated behavior analysis.Existing multianimal pose estimation workflows rely on tracking-bydetection frameworks for either bottom-up or top-down approaches,requiring retraining to accommodate diverse animal appearances.This study introduces InteBOMB,an integrated workflow that enhances top-down approaches by incorporating generic object tracking,eliminating the need for prior knowledge of target animals while maintaining broad generalizability.InteBOMB includes two key strategies for tracking and segmentation in laboratory environments and two techniques for pose estimation in natural settings.The“background enhancement”strategy optimizesforeground-backgroundcontrastiveloss,generating more discriminative correlation maps.The“online proofreading”strategy stores human-in-the-loop long-term memory and dynamic short-term memory,enabling adaptive updates to object visual features.The“automated labeling suggestion”technique reuses the visual features saved during tracking to identify representative frames for training set labeling.Additionally,the“joint behavior analysis”technique integrates these features with multimodal data,expanding the latent space for behavior classification and clustering.To evaluate the framework,six datasets of mice and six datasets of nonhuman primates were compiled,covering laboratory and natural scenes.Benchmarking results demonstrated a24%improvement in zero-shot generic tracking and a 21%enhancement in joint latent space performance across datasets,highlighting the effectiveness of this approach in robust,generalizable behavior analysis.展开更多
Using the HST observation data of BL Lac objects by Urry et al. and γ-ray observation data, we find that there is a correlation between Fγ and Fonuclei forγ-ray-loud BL Lac objects (correlation coefficients: 7γ=0....Using the HST observation data of BL Lac objects by Urry et al. and γ-ray observation data, we find that there is a correlation between Fγ and Fonuclei forγ-ray-loud BL Lac objects (correlation coefficients: 7γ=0.63,p = 4.0 × 10-2), but no correlation between Fγ and Fohost, where Fonuclei and Fohost are the fluxes of nuclei and host galaxy in V-band. For 19γ-ray-loud BL Lac objects with observed spectral index in multi-wavebands, the spectral index correlations between any two bands are as follow: (1) there is a strong correlation between aγ and aK for 15 BL Lac objects(γ = 0.84,p = 3.11 × 10-4); (2) the correlation between aγ and ao for 12 BL Lac objects isγ = 0.82, p = 1.5 × 10-3; (3) there is no correlation between a7 and ax for 16 BL Lac objects. The results, together with characteristic double-humped shape of their SEDs, show that the synchrotron self-Compton mechanism might be a main mechanism for theγ-ray emission of the BL Lac objects. The electrons emitting JR and optical radiation via synchrotron are also responsible for upscattering these photons toγ-rays, and a variability in IR-optical regime should be accompanied by a change in theγ-rays.展开更多
We make a statistical study of the energy sources of high-velocity phenomena, Herbig-Haro (HH) objects. IRAS counterparts of HH objects are identified. Their colors, brightness, geometric relation to the RH objects an...We make a statistical study of the energy sources of high-velocity phenomena, Herbig-Haro (HH) objects. IRAS counterparts of HH objects are identified. Their colors, brightness, geometric relation to the RH objects and SED are analysed. The sources are found to be concentrated in a band-shaped region in the IRAS color-color diagram. We suggest an explanation of thick surrounding material for this distribution. We propose a new method for identifying the energy sources based on color arid brightness. This method is applied to more than 200 HR objects whose energy sources are still unknown. Finally, a group of very young stellar object candidates which have similar properties to the RH energy sources is picked out. Their large-scale distribution is discussed.展开更多
Considering the defects of conventional optimization methods, a novel optimization algorithm is introduced in this paper. Target space partitioning method is used in this algorithm to solve multi-objective optimizatio...Considering the defects of conventional optimization methods, a novel optimization algorithm is introduced in this paper. Target space partitioning method is used in this algorithm to solve multi-objective optimization problem, thus achieve the coherent solution which can meet the requirements of all target functions, and improve the population's overall evolution level. The algorithm which guarantees diversity preservation and fast convergence to the Pareto set is applied to structural optimization problems. The empirical analysis supports the algorithm and gives an example with program.展开更多
The efficiency of organic semiconductor photocatalysts is typically limited by their capability of photogenerated electron transport.Herein,a photocatalyst is proposed initially through the specific axial coordination...The efficiency of organic semiconductor photocatalysts is typically limited by their capability of photogenerated electron transport.Herein,a photocatalyst is proposed initially through the specific axial coordination interaction between imidazole-C_(60)(ImC_(60))and zinc tetraphenyl porphyrin(ZnTPP)named ImC_(60)-ZnTPP.Subsequently,detailed structural characterizations along with theoretical calculation reveal that the unique ImC_(60)-ZnTPP possesses head-to-tail stacking supra-structures,leading to the formation of a continuous array of C_(60)–C_(60) with ultrashort spacing and ensuring strongπ–πinteractions and homogeneous electronic coupling,which could tremendously promote electron transport along the(−111)crystal facet of ImC_(60)-ZnTPP.Consequently,compared to other fullerene-based photocatalysts,ImC_(60)-ZnTPP shows exceptional photocatalytic hydrogen production activity,with an efficiency of up to 80.95 mmol g^(-1) h^(-1).This study provides a novel strategy to design highly efficient fullerene-based photocatalytic systems for solar-driven energy conversion and extend their artificial photosynthetic use.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:61602157Henan scientific and technological project,Grant/Award Number:242102210020Basal Research Fund,Grant/Award Number:NSFRF240618。
文摘In the metric-based meta-learning detection model,the distribution of training samples in the metric space has great influence on the detection performance,and this influence is usually ignored by traditional meta-detectors.In addition,the design of metric space might be interfered with by the background noise of training samples.To tackle these issues,we propose a metric space optimisation method based on hyperbolic geometry attention and class-agnostic activation maps.First,the geometric properties of hyperbolic spaces to establish a structured metric space are used.A variety of feature samples of different classes are embedded into the hyperbolic space with extremely low distortion.This metric space is more suitable for representing tree-like structures between categories for image scene analysis.Meanwhile,a novel similarity measure function based on Poincarédistance is proposed to evaluate the distance of various types of objects in the feature space.In addition,the class-agnostic activation maps(CCAMs)are employed to re-calibrate the weight of foreground feature information and suppress background information.Finally,the decoder processes the high-level feature information as the decoding of the query object and detects objects by predicting their locations and corresponding task encodings.Experimental evaluation is conducted on Pascal VOC and MS COCO datasets.The experiment results show that the effectiveness of the authors’method surpasses the performance baseline of the excellent few-shot detection models.
基金Under the auspices of National Natural Science Foundation of China(No.42401232,72050001)Natural Science Foundation of Gansu Province(No.24JRRA419)Research Funds for Blue Green Infrastructure Planning and Ecological Restoration in Mining Cities(No.071124044/(24)0315)。
文摘Urban open spaces(UOS)play a crucial role in enhancing city livability and resident well-being,yet there remains a gap in utilizing social media to analyze changes in UOS utilization across different COVID(Corona Virus Disease)-19 phases.Our research applied Sina Weibo data to scrutinize UOS engagement across pre-pandemic(2019),pandemic(2021),and post-pandemic(2023)periods in Lanzhou City,China,revealing evolving spatiotemporal patterns and highlighting the pandemic's impact on UOS usage.Initially,scenic mountains and urban parks dominated visitor preferences in 2019.However,during the pandemic,there was a trend towards destinations that combined elements of tourism,business,entertainment,and culture,reflecting a growing appetite for diverse experiences.Despite this shift,the post-pandemic period did not see a complete return to pre-pandemic travel patterns,with a noticeable decline in visits to traditional green open spaces during lockdowns.We identified key attractions in main urban areas,highlighting geographical variations in tourism and Cultural Ecosystem Services(CES)distribution that warrant further attention.The post-pandemic landscape reveals a resurging interest in green-blue spaces and nature-focused tourism,highlighting a continued preference for cultural and natural experiences,and emphasizing the need to harmonize development with the preservation of natural and cultural heritage.This study introduces the use of social media data across pandemic phases to guide UOS management,offering insights for creating resilient,multifunctional urban spaces that address public needs and enhance community well-being.
文摘This paper deals with the re-entry predictions of the space objects from the low eccentric orbit. Any re-entering object re-enters the Earth’s atmosphere with a high orbital velocity. Due to the aerodynamic heating the object tends to break into multiple fragments which later pose a great risk hazard to the population. Here a satellite is considered as the space object for which the re-entry prediction is made. This prediction is made with a package where the trajectory path, the time of re-entry and the survival rate of the fragments is done. The prediction is done using DRAMA 2.0—ESA’s Debris Risk Assessment and Mitigation Analysis Tool suite, MATLAB and Numerical Prediction of Orbital Events software. The predicted re-entry time of OSIRIS 3U was found to be on 7th March 2019, 7:25 (UTC), whereas the actual re-entry time was on 7th March 2019, 7:03 (UTC). The trajectory path found was 51.5699 deg. (Lat), −86.5738 deg. (Long.) with an altitude of 168.643 km. But the actual trajectory was 51.76 deg. (Lat), −89.01deg. (Long.) with an altitude of 143.5 km.
基金the National Natural Science Foundation of China[Grant No.41874035]the National Natural Science Foundation of China[Grant No.12103035]+1 种基金the Natural Science Foundation of Hubei province,China[Grant No.2020CFB396]the Fundamental Research Funds for the Central Universities,China[Grant No.2042021kf0001].
文摘With the undergoing and planned implementations of mega constellations of thousands of Low Earth Orbiting(LEO)satellites,space will become even more congested for satellite operations.The enduring effects on the long-term space environment have been investigated by various researchers using debris environment models.This paper is focused on the imminent short-term effects of LEO mega constellations on the space operation environment concerned by satellite owners and operators.The effects are measured in terms of the Close Approaches(CAs)and overall collision probability.Instead of using debris environment models,the CAs are determined from integrated orbit positions,and the collision probability is computed for each CA considering the sizes and position covariance of the involving objects.The obtained results thus present a clearer picture of the space operation safety environment when LEO mega constellations are deployed.Many mega constellations are simulated,including a Starlink-like constellation of 1584 satellites,four possible generic constellations at altitudes between 1110 km and 1325 km,and three constellations of 1584 satellites each at the altitudes of 650 km,800 km,and 950 km,respectively,where the Resident Space Object(RSO)spatial density is the highest.The increases in the number of CAs and overall collision probability caused by them are really alarming.The results suggest that highly frequent orbital maneuvers are required to avoid collisions between existing RSOs and constellation satellites,and between satellites from two constellations at a close altitude,as such the constellation operation burden would be very heavy.The study is not only useful for satellite operators but a powerful signal for various stakeholders to pay serious attention to the development of LEO mega constellations.
文摘A soitable data model and data structure make underground survey objects maintained and operated easier. This paper gives a formal definition for underground survey objects. By making use of the quotient topological space, the author studies the logical relations among underground survey objects, a partiallyordered space uuder some conditions. An example is given to show the data model’s possible applications.
基金co-supported by the National Natural Science Foundation of China (Grant Nos. 61371134, 61071137)the National Basic Research Program of China (No. 2010CB327900)
文摘The application of high-performance imaging sensors in space-based space surveillance systems makes it possible to recognize space objects and estimate their poses using vision-based methods. In this paper, we proposed a kernel regression-based method for joint multi-view space object recognition and pose estimation. We built a new simulated satellite image dataset named BUAA-SID 1.5 to test our method using different image representations. We evaluated our method for recognition-only tasks, pose estimation-only tasks, and joint recognition and pose estimation tasks. Experimental results show that our method outperforms the state-of-the-arts in space object recognition, and can recognize space objects and estimate their poses effectively and robustly against noise and lighting conditions.
文摘快速城市化加剧了社会发展与生态保护之间的矛盾,如何利用集约的资源要素实现社会-生态效益优化,是城市可持续发展的关键。以上海市中心城区为研究对象,基于多目标规划(multiple objective planning,MOP)模型设置效益目标函数和约束条件嵌入斑块生成土地利用变化模拟模型(patchgenerating land use simulation model,PLUS),实现多元目标下城市绿地生态网络多情景模拟及功能评价,以期为未来城市绿地生态网络高效构建、土地利用规划决策提供参考。结果表明:1)耦合MOP模型和PLUS模型,基于土地资源多效益目标的定量化求解,可以寻求社会-生态效益最优化的关键拐点;2)不同效益目标导向下,可持续发展情景较经济发展情景和生态保护情景,耕地、林地、水域等各用地类型的相互转化,以及经济发展和生态保护之间的关系均处于相对稳定状态;3)可持续发展情景的各项绿地生态网络测度指标均介于其他2个用地情景之间,重要斑块的数量及空间分布表征,在优化社会-生态效益、城市土地利用结构配置的同时,城市绿地生态网络功能也得到提升。研究成果为超大城市高密区绿地生态网络结构功能完善、土地利用规划科学决策、城市社会-生态系统综合效益提升提供科学参考。
文摘A scheduling model of closely spaced parallel runways for arrival aircraft was proposed,with multi-objections of the minimum flight delay cost,the maximum airport capacity,the minimum workload of air traffic controller and the maximum fairness of airlines′scheduling.The time interval between two runways and changes of aircraft landing order were taken as the constraints.Genetic algorithm was used to solve the model,and the model constrained unit delay cost of the aircraft with multiple flight tasks to reduce its delay influence range.Each objective function value or the fitness of particle unsatisfied the constrain condition would be punished.Finally,one domestic airport hub was introduced to verify the algorithm and the model.The results showed that the genetic algorithm presented strong convergence and timeliness for solving constraint multi-objective aircraft landing problem on closely spaced parallel runways,and the optimization results were better than that of actual scheduling.
基金This work is supported and funded by NSFC(Natural Science Foundation of China)[No.51905272].
文摘As the number of space objects(SO)increases,collision avoidance problem in the rendezvous tasks or reconstellation of satellites with SO has been paid more attention,and the dangerous area of a possible collision should be derived.In this paper,a maneuvering method is proposed for avoiding collision with a space debris object in the phasing orbit of the initial optimal solution.Accordingly,based on the plane of eccentricity vector components,relevant dangerous area which is bounded by two parallel lines is formulated.The axises of eccentricity vector system pass through the end of eccentricity vector of phasing orbit in the optimal solution,and orientation of axis depends on the latitude argument where a collision will occur.The dangerous area is represented especially with the graphical dialogue,and it allows to find a compromise between the SO avoiding and the fuel consumption reduction.The proposed method to solve the collision avoidance problem provides simplicity to calculate rendezvous maneuvers,and possibility to avoid collisions from several collisions or from“slow”collisions in a phasing orbit,when the protected spacecraft and the object fly dangerously close to each other for a long period.
文摘This paper mainly focuses on the issues about generic multi-scale object perception for detection or recognition. A novel computational model in visually-feature space is presented for scene & object representation to purse the underlying textural manifold statistically in nonparametric manner. The associative method approximately makes perceptual hierarchy in human-vision biologically coherency in specific quad-tree-pyramid structure, and the appropriate scale-value of different objects can automatically be selected by evaluating from well-defined scale function without any priori knowledge. The sufficient experiments truly demonstrate the effectiveness of scale determination in textural manifold with object localization rapidly.
基金supported by the STI 2030-Major Projects(2022ZD0211900,2022ZD0211902)STI 2030-Major Projects(2021ZD0204500,2021ZD0204503)+1 种基金National Natural Science Foundation of China(32171461)National Key Research and Development Program of China(2023YFC3208303)。
文摘Advancements in animal behavior quantification methods have driven the development of computational ethology,enabling fully automated behavior analysis.Existing multianimal pose estimation workflows rely on tracking-bydetection frameworks for either bottom-up or top-down approaches,requiring retraining to accommodate diverse animal appearances.This study introduces InteBOMB,an integrated workflow that enhances top-down approaches by incorporating generic object tracking,eliminating the need for prior knowledge of target animals while maintaining broad generalizability.InteBOMB includes two key strategies for tracking and segmentation in laboratory environments and two techniques for pose estimation in natural settings.The“background enhancement”strategy optimizesforeground-backgroundcontrastiveloss,generating more discriminative correlation maps.The“online proofreading”strategy stores human-in-the-loop long-term memory and dynamic short-term memory,enabling adaptive updates to object visual features.The“automated labeling suggestion”technique reuses the visual features saved during tracking to identify representative frames for training set labeling.Additionally,the“joint behavior analysis”technique integrates these features with multimodal data,expanding the latent space for behavior classification and clustering.To evaluate the framework,six datasets of mice and six datasets of nonhuman primates were compiled,covering laboratory and natural scenes.Benchmarking results demonstrated a24%improvement in zero-shot generic tracking and a 21%enhancement in joint latent space performance across datasets,highlighting the effectiveness of this approach in robust,generalizable behavior analysis.
基金This work was financially supported by the National Natural Science FoUndation of ChinaNatural Science Foundation of YUJman
文摘Using the HST observation data of BL Lac objects by Urry et al. and γ-ray observation data, we find that there is a correlation between Fγ and Fonuclei forγ-ray-loud BL Lac objects (correlation coefficients: 7γ=0.63,p = 4.0 × 10-2), but no correlation between Fγ and Fohost, where Fonuclei and Fohost are the fluxes of nuclei and host galaxy in V-band. For 19γ-ray-loud BL Lac objects with observed spectral index in multi-wavebands, the spectral index correlations between any two bands are as follow: (1) there is a strong correlation between aγ and aK for 15 BL Lac objects(γ = 0.84,p = 3.11 × 10-4); (2) the correlation between aγ and ao for 12 BL Lac objects isγ = 0.82, p = 1.5 × 10-3; (3) there is no correlation between a7 and ax for 16 BL Lac objects. The results, together with characteristic double-humped shape of their SEDs, show that the synchrotron self-Compton mechanism might be a main mechanism for theγ-ray emission of the BL Lac objects. The electrons emitting JR and optical radiation via synchrotron are also responsible for upscattering these photons toγ-rays, and a variability in IR-optical regime should be accompanied by a change in theγ-rays.
文摘We make a statistical study of the energy sources of high-velocity phenomena, Herbig-Haro (HH) objects. IRAS counterparts of HH objects are identified. Their colors, brightness, geometric relation to the RH objects and SED are analysed. The sources are found to be concentrated in a band-shaped region in the IRAS color-color diagram. We suggest an explanation of thick surrounding material for this distribution. We propose a new method for identifying the energy sources based on color arid brightness. This method is applied to more than 200 HR objects whose energy sources are still unknown. Finally, a group of very young stellar object candidates which have similar properties to the RH energy sources is picked out. Their large-scale distribution is discussed.
基金National Natural Science Foundations of China (No. 60970004, No. 60743010)Natural Science Foundation of ShandongProvince, China (No. Z2008G02)
文摘Considering the defects of conventional optimization methods, a novel optimization algorithm is introduced in this paper. Target space partitioning method is used in this algorithm to solve multi-objective optimization problem, thus achieve the coherent solution which can meet the requirements of all target functions, and improve the population's overall evolution level. The algorithm which guarantees diversity preservation and fast convergence to the Pareto set is applied to structural optimization problems. The empirical analysis supports the algorithm and gives an example with program.
基金supported by the National Natural Science Foundation of China(52322204,52072374,52272052)the National Key R&D Program of China(Grant No.2022YFA1205900)the Youth Innovation Promotion Association of CAS(Y2022015).
文摘The efficiency of organic semiconductor photocatalysts is typically limited by their capability of photogenerated electron transport.Herein,a photocatalyst is proposed initially through the specific axial coordination interaction between imidazole-C_(60)(ImC_(60))and zinc tetraphenyl porphyrin(ZnTPP)named ImC_(60)-ZnTPP.Subsequently,detailed structural characterizations along with theoretical calculation reveal that the unique ImC_(60)-ZnTPP possesses head-to-tail stacking supra-structures,leading to the formation of a continuous array of C_(60)–C_(60) with ultrashort spacing and ensuring strongπ–πinteractions and homogeneous electronic coupling,which could tremendously promote electron transport along the(−111)crystal facet of ImC_(60)-ZnTPP.Consequently,compared to other fullerene-based photocatalysts,ImC_(60)-ZnTPP shows exceptional photocatalytic hydrogen production activity,with an efficiency of up to 80.95 mmol g^(-1) h^(-1).This study provides a novel strategy to design highly efficient fullerene-based photocatalytic systems for solar-driven energy conversion and extend their artificial photosynthetic use.
