Traditional inverse synthetic aperture radar(ISAR)imaging methods for maneuvering targets have low resolution and poor capability of noise suppression. An ISAR imaging method of maneuvering targets based on phase retr...Traditional inverse synthetic aperture radar(ISAR)imaging methods for maneuvering targets have low resolution and poor capability of noise suppression. An ISAR imaging method of maneuvering targets based on phase retrieval is proposed,which can provide a high-resolution and focused map of the spatial distribution of scatterers on the target. According to theoretical derivation, the modulus of raw data from the maneuvering target is not affected by radial motion components for ISAR imaging system, so the phase retrieval algorithm can be used for ISAR imaging problems. However, the traditional phase retrieval algorithm will be not applicable to ISAR imaging under the condition of random noise. To solve this problem, an algorithm is put forward based on the range Doppler(RD) algorithm and oversampling smoothness(OSS) phase retrieval algorithm. The algorithm captures the target information in order to reduce the influence of the random phase on ISAR echoes, and then applies OSS for focusing imaging based on prior information of the RD algorithm. The simulated results demonstrate the validity of this algorithm, which cannot only obtain high resolution imaging for high speed maneuvering targets under the condition of random noise, but also substantially improve the success rate of the phase retrieval algorithm.展开更多
A novel image retrieval approach based on color features and anisotropic directional information is proposed for content based image retrieval systems （CBIR）. The color feature is described by the color histogram ...A novel image retrieval approach based on color features and anisotropic directional information is proposed for content based image retrieval systems （CBIR）. The color feature is described by the color histogram （CH）, which is translation and rotation invariant. However, the CH does not contain spatial information which is very important for the image retrieval. To overcome this shortcoming, the subband energy of the lifting directionlet transform （L-DT） is proposed to describe the directional information, in which L-DT is characterized by multi-direction and anisotropic basis functions compared with the wavelet transform. A global similarity measure is designed to implement the fusion of both color feature and anisotropic directionality for the retrieval process. The retrieval experiments using a set of COREL images demonstrate that the higher query precision and better visual effect can be achieved.展开更多
A retrieval control strategy for failed satellite,which is connected to a servicing spacecraft by a tether,is studied.The Lagrange analytical mechanics based dynamics modeling for the system composed of a servicing sp...A retrieval control strategy for failed satellite,which is connected to a servicing spacecraft by a tether,is studied.The Lagrange analytical mechanics based dynamics modeling for the system composed of a servicing spacecraft,a tether and a failed satellite,is presented under the earth center inertia coordinate system,then model simplification is conducted under the assumption that the failed satellite’s mass is far smaller than the servicing spacecraft’s,meanwhile the tether’s length is far smaller than the size of the servicing spacecraft’s orbit.Analysis shows that the retrieval process is intrinsically unstable as the Coriolis force functions is a negative damping.A retrieval strategy based on only the tether’s tension is designed,resulting in the fastest retrieval speed.In the proposed strategy,firstly,the tether’s swing angle amplitude is adjusted to 45?by deploying/retrieving the tether;then the tether swings freely with fixed length until it reaches negative maximum angle–45?;finally,the tether is retrieved by the pre-assigned exponential law.For simplicity,only the coplanar situation,that the tether swings in the plane of the servicing spacecraft’s orbit,is studied.Numerical simulation verifies the effectiveness of the strategy proposed.展开更多
Two lines of image representation based on multiple features fusion demonstrate excellent performance in image retrieval.However,there are some problems in both of them:1)the methods defining directly texture in color...Two lines of image representation based on multiple features fusion demonstrate excellent performance in image retrieval.However,there are some problems in both of them:1)the methods defining directly texture in color space put more emphasis on color than texture feature;2)the methods extract several features respectively and combine them into a vector,in which bad features may lead to worse performance after combining directly good and bad features.To address the problems above,a novel hybrid framework for color image retrieval through combination of local and global features achieves higher retrieval precision.The bag-of-visual words(BoW)models and color intensity-based local difference patterns(CILDP)are exploited to capture local and global features of an image.The proposed fusion framework combines the ranking results of BoW and CILDP through graph-based density method.The performance of our proposed framework in terms of average precision on Corel-1K database is86.26%,and it improves the average precision by approximately6.68%and12.53%over CILDP and BoW,respectively.Extensive experiments on different databases demonstrate the effectiveness of the proposed framework for image retrieval.展开更多
A simple fast method is given for sequentially retrieving all the records in a B tree. A file structure for database is proposed. The records in its primary data file are sorted according to the key order. A B tree ...A simple fast method is given for sequentially retrieving all the records in a B tree. A file structure for database is proposed. The records in its primary data file are sorted according to the key order. A B tree is used as its dense index. It is easy to insert, delete or search a record, and it is also convenient to retrieve records in the sequential order of the keys. The merits and efficiencies of these methods or structures are discussed in detail.展开更多
This paper presents a novel efficient semantic image classification algorithm for high-level feature indexing of high-dimension image database. Experiments show that the algorithm performs well. The size of the train ...This paper presents a novel efficient semantic image classification algorithm for high-level feature indexing of high-dimension image database. Experiments show that the algorithm performs well. The size of the train set and the test set is 7 537 and 5 000 respectively. Based on this theory, another ground is built with 12,000 images, which are divided into three classes: city, landscape and person, the total result of the classifications is 88.92%, meanwhile, some preliminary results are presented for image understanding based on semantic image classification and low level features. The groundtruth for the experiments is built with the images from Corel database, photos and some famous face databases.展开更多
To realize content-hased retrieval of large image databases, it is required to develop an efficient index and retrieval scheme. This paper proposes an index algorithm of clustering called CMA, which supports fast retr...To realize content-hased retrieval of large image databases, it is required to develop an efficient index and retrieval scheme. This paper proposes an index algorithm of clustering called CMA, which supports fast retrieval of large image databases. CMA takes advantages of k-means and self-adaptive algorithms. It is simple and works without any user interactions. There are two main stages in this algorithm. In the first stage, it classifies images in a database into several clusters, and automatically gets the necessary parameters for the next stage-k-means iteration. The CMA algorithm is tested on a large database of more than ten thousand images and compare it with k-means algorithm. Experimental results show that this algorithm is effective in both precision and retrieval time.展开更多
The problem considered in this paper is how to detect the degree of similarity in the content of digital images useful in image retrieval,i.e.,to what extent is the content of a query image similar to content of other...The problem considered in this paper is how to detect the degree of similarity in the content of digital images useful in image retrieval,i.e.,to what extent is the content of a query image similar to content of other images.The solution to this problem results from the detection of subsets that are rough sets contained in covers of digital images determined by perceptual tolerance relations(PTRs).Such relations are defined within the context of perceptual representative spaces that hearken back to work by J.H.Poincare on representative spaces as models of physical continua.Classes determined by a PTR provide content useful in content-based image retrieval(CBIR).In addition,tolerance classes provide a means of determining when subsets of image covers are tolerance rough sets(TRSs).It is the nearness of TRSs present in image tolerance spaces that provide a promising approach to CBIR,especially in cases such as satellite images or aircraft identification where there are subtle differences between pairs of digital images,making it difficult to quantify the similarities between such images.The contribution of this article is the introduction of the nearness of tolerance rough sets as an effective means of measuring digital image similarities and,as a significant consequence,successfully carrying out CBIR.展开更多
A novel content based image retrieval （CBIR） algorithmusing relevant feedback is presented. The proposed frameworkhas three major contributions： a novel feature descriptor calledcolor spectral histogram （CSH） to ...A novel content based image retrieval （CBIR） algorithmusing relevant feedback is presented. The proposed frameworkhas three major contributions： a novel feature descriptor calledcolor spectral histogram （CSH） to measure the similarity betweenimages; two-dimensional matrix based indexing approach proposedfor short-term learning （STL）; and long-term learning （LTL）.In general, image similarities are measured from feature representationwhich includes color quantization, texture, color, shapeand edges. However, CSH can describe the image feature onlywith the histogram. Typically the image retrieval process starts byfinding the similarity between the query image and the imagesin the database; the major computation involved here is that theselection of top ranking images requires a sorting algorithm to beemployed at least with the lower bound of O（n log n）. A 2D matrixbased indexing of images can enormously reduce the searchtime in STL. The same structure is used for LTL with an aim toreduce the amount of log to be maintained. The performance ofthe proposed framework is analyzed and compared with the existingapproaches, the quantified results indicates that the proposedfeature descriptor is more effectual than the existing feature descriptorsthat were originally developed for CBIR. In terms of STL,the proposed 2D matrix based indexing minimizes the computationeffort for retrieving similar images and for LTL, the proposed algorithmtakes minimum log information than the existing approaches.展开更多
Piezocatalysis and pyrocatalysis can achieve catalytic action with the application of external mechanical energy and varying temperatures.These catalytic processes have been widely applied in various fields,providing ...Piezocatalysis and pyrocatalysis can achieve catalytic action with the application of external mechanical energy and varying temperatures.These catalytic processes have been widely applied in various fields,providing innovative solutions to issues such as water pollution,energy shortages,and global warming.Despite the continuous breakthroughs in the catalytic performance of piezocatalysts and pyrocatalysts,powder-based catalysts face significant limitations due to their inability to be retrieved and the risk of secondary pollution,severely restricting their application.Methods such as compression molding,3 D printing,and the preparation of ceramic-polymer bulk composites can effectively address the issue of catalyst retrievability.However,bulk catalysts,which lose a significant amount of surface area,still need their catalytic performance further enhanced.Therefore,achieving piezocatalysts and pyrocatalysts with excellent catalytic performance and retrievability is of increasing importance.展开更多
To retrieve sea-surface salinity (SSS) from radiometer data at 1.4 GHz, auxiliary data of sea-surface temperature (SST), surface roughness and meteorological variables are needed. The authors study oceanic passive pol...To retrieve sea-surface salinity (SSS) from radiometer data at 1.4 GHz, auxiliary data of sea-surface temperature (SST), surface roughness and meteorological variables are needed. The authors study oceanic passive polarimetric microwave remote sensing using 1.4 GHz and 10.7 GHz bands. A set of algorithms are developed for 1.4 GHz and 10.7 GHz microwave polarimetric radiometer at 50° incidence angle to retrieve wind vector, as well as other geophysical parameters, such as SSS, SST, atmospheric volumes of water vapor and liquid water. Idealized retrievals are conducted using 2 324 simulated brightness temperatures of full Stokes parameters at 1.4 GHz and 10.7 GHz. Results indicate that SSS, SST, sea-surface wind speed, direction, atmospheric volumes of water vapor and liquid water can be inversed at the same time. This suggests an alternative way for SSS remote sensing.展开更多
大语言模型(LLMs,Large Language Models)具有极强的自然语言理解和复杂问题求解能力,本文基于大语言模型构建了矿物问答系统,以高效地获取矿物知识。该系统首先从互联网资源获取矿物数据,清洗后将矿物数据结构化为矿物文档和问答对;将...大语言模型(LLMs,Large Language Models)具有极强的自然语言理解和复杂问题求解能力,本文基于大语言模型构建了矿物问答系统,以高效地获取矿物知识。该系统首先从互联网资源获取矿物数据,清洗后将矿物数据结构化为矿物文档和问答对;将矿物文档经过格式转换和建立索引后转化为矿物知识库,用于检索增强大语言模型生成,问答对用于微调大语言模型。使用矿物知识库检索增强大语言模型生成时,采用先召回再精排的两级检索模式,以获得更好的大语言模型生成结果。矿物大语言模型微调采用了主流的低秩适配(Low-Rank Adaption,LoRA)方法,以较少的训练参数获得了与全参微调性能相当的效果,节省了计算资源。实验结果表明,基于检索增强生成的大语言模型的矿物问答系统能以较高的准确率快捷地获取矿物知识。展开更多
基金supported by the National Natural Science Foundation of China(6157138861601398)the National Natural Science Foundation of Hebei Province(F2016203251)
文摘Traditional inverse synthetic aperture radar(ISAR)imaging methods for maneuvering targets have low resolution and poor capability of noise suppression. An ISAR imaging method of maneuvering targets based on phase retrieval is proposed,which can provide a high-resolution and focused map of the spatial distribution of scatterers on the target. According to theoretical derivation, the modulus of raw data from the maneuvering target is not affected by radial motion components for ISAR imaging system, so the phase retrieval algorithm can be used for ISAR imaging problems. However, the traditional phase retrieval algorithm will be not applicable to ISAR imaging under the condition of random noise. To solve this problem, an algorithm is put forward based on the range Doppler(RD) algorithm and oversampling smoothness(OSS) phase retrieval algorithm. The algorithm captures the target information in order to reduce the influence of the random phase on ISAR echoes, and then applies OSS for focusing imaging based on prior information of the RD algorithm. The simulated results demonstrate the validity of this algorithm, which cannot only obtain high resolution imaging for high speed maneuvering targets under the condition of random noise, but also substantially improve the success rate of the phase retrieval algorithm.
基金supported by the National High Technology Research and Development Program of China (863 Program) (2007AA12Z1362007AA12Z223)+2 种基金the National Basic Research Program of China (973Program) (2006CB705707)the National Natural Science Foundation of China (60672126, 60607010)the Program for Cheung Kong Scholars and Innovative Research Team in University (IRT0645)
文摘A novel image retrieval approach based on color features and anisotropic directional information is proposed for content based image retrieval systems （CBIR）. The color feature is described by the color histogram （CH）, which is translation and rotation invariant. However, the CH does not contain spatial information which is very important for the image retrieval. To overcome this shortcoming, the subband energy of the lifting directionlet transform （L-DT） is proposed to describe the directional information, in which L-DT is characterized by multi-direction and anisotropic basis functions compared with the wavelet transform. A global similarity measure is designed to implement the fusion of both color feature and anisotropic directionality for the retrieval process. The retrieval experiments using a set of COREL images demonstrate that the higher query precision and better visual effect can be achieved.
基金supported by the Fundamental Research Funds for the Central Universities(NUAA-NS2016082)
文摘A retrieval control strategy for failed satellite,which is connected to a servicing spacecraft by a tether,is studied.The Lagrange analytical mechanics based dynamics modeling for the system composed of a servicing spacecraft,a tether and a failed satellite,is presented under the earth center inertia coordinate system,then model simplification is conducted under the assumption that the failed satellite’s mass is far smaller than the servicing spacecraft’s,meanwhile the tether’s length is far smaller than the size of the servicing spacecraft’s orbit.Analysis shows that the retrieval process is intrinsically unstable as the Coriolis force functions is a negative damping.A retrieval strategy based on only the tether’s tension is designed,resulting in the fastest retrieval speed.In the proposed strategy,firstly,the tether’s swing angle amplitude is adjusted to 45?by deploying/retrieving the tether;then the tether swings freely with fixed length until it reaches negative maximum angle–45?;finally,the tether is retrieved by the pre-assigned exponential law.For simplicity,only the coplanar situation,that the tether swings in the plane of the servicing spacecraft’s orbit,is studied.Numerical simulation verifies the effectiveness of the strategy proposed.
基金Projects(61370200,61672130,61602082) supported by the National Natural Science Foundation of ChinaProject(1721203049-1) supported by the Science and Technology Research and Development Plan Project of Handan,Hebei Province,China
文摘Two lines of image representation based on multiple features fusion demonstrate excellent performance in image retrieval.However,there are some problems in both of them:1)the methods defining directly texture in color space put more emphasis on color than texture feature;2)the methods extract several features respectively and combine them into a vector,in which bad features may lead to worse performance after combining directly good and bad features.To address the problems above,a novel hybrid framework for color image retrieval through combination of local and global features achieves higher retrieval precision.The bag-of-visual words(BoW)models and color intensity-based local difference patterns(CILDP)are exploited to capture local and global features of an image.The proposed fusion framework combines the ranking results of BoW and CILDP through graph-based density method.The performance of our proposed framework in terms of average precision on Corel-1K database is86.26%,and it improves the average precision by approximately6.68%and12.53%over CILDP and BoW,respectively.Extensive experiments on different databases demonstrate the effectiveness of the proposed framework for image retrieval.
文摘A simple fast method is given for sequentially retrieving all the records in a B tree. A file structure for database is proposed. The records in its primary data file are sorted according to the key order. A B tree is used as its dense index. It is easy to insert, delete or search a record, and it is also convenient to retrieve records in the sequential order of the keys. The merits and efficiencies of these methods or structures are discussed in detail.
文摘This paper presents a novel efficient semantic image classification algorithm for high-level feature indexing of high-dimension image database. Experiments show that the algorithm performs well. The size of the train set and the test set is 7 537 and 5 000 respectively. Based on this theory, another ground is built with 12,000 images, which are divided into three classes: city, landscape and person, the total result of the classifications is 88.92%, meanwhile, some preliminary results are presented for image understanding based on semantic image classification and low level features. The groundtruth for the experiments is built with the images from Corel database, photos and some famous face databases.
基金This project was supported by National High Tech Foundation of 863 (2001AA115123)
文摘To realize content-hased retrieval of large image databases, it is required to develop an efficient index and retrieval scheme. This paper proposes an index algorithm of clustering called CMA, which supports fast retrieval of large image databases. CMA takes advantages of k-means and self-adaptive algorithms. It is simple and works without any user interactions. There are two main stages in this algorithm. In the first stage, it classifies images in a database into several clusters, and automatically gets the necessary parameters for the next stage-k-means iteration. The CMA algorithm is tested on a large database of more than ten thousand images and compare it with k-means algorithm. Experimental results show that this algorithm is effective in both precision and retrieval time.
基金supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) research grants 194376 and 185986Manitoba Centre of Excellence Fund(MCEF) grant and Canadian Network Centre of Excellence(NCE) and Canadian Arthritis Network(CAN) grant SRI-BIO-05.
文摘The problem considered in this paper is how to detect the degree of similarity in the content of digital images useful in image retrieval,i.e.,to what extent is the content of a query image similar to content of other images.The solution to this problem results from the detection of subsets that are rough sets contained in covers of digital images determined by perceptual tolerance relations(PTRs).Such relations are defined within the context of perceptual representative spaces that hearken back to work by J.H.Poincare on representative spaces as models of physical continua.Classes determined by a PTR provide content useful in content-based image retrieval(CBIR).In addition,tolerance classes provide a means of determining when subsets of image covers are tolerance rough sets(TRSs).It is the nearness of TRSs present in image tolerance spaces that provide a promising approach to CBIR,especially in cases such as satellite images or aircraft identification where there are subtle differences between pairs of digital images,making it difficult to quantify the similarities between such images.The contribution of this article is the introduction of the nearness of tolerance rough sets as an effective means of measuring digital image similarities and,as a significant consequence,successfully carrying out CBIR.
文摘A novel content based image retrieval （CBIR） algorithmusing relevant feedback is presented. The proposed frameworkhas three major contributions： a novel feature descriptor calledcolor spectral histogram （CSH） to measure the similarity betweenimages; two-dimensional matrix based indexing approach proposedfor short-term learning （STL）; and long-term learning （LTL）.In general, image similarities are measured from feature representationwhich includes color quantization, texture, color, shapeand edges. However, CSH can describe the image feature onlywith the histogram. Typically the image retrieval process starts byfinding the similarity between the query image and the imagesin the database; the major computation involved here is that theselection of top ranking images requires a sorting algorithm to beemployed at least with the lower bound of O（n log n）. A 2D matrixbased indexing of images can enormously reduce the searchtime in STL. The same structure is used for LTL with an aim toreduce the amount of log to be maintained. The performance ofthe proposed framework is analyzed and compared with the existingapproaches, the quantified results indicates that the proposedfeature descriptor is more effectual than the existing feature descriptorsthat were originally developed for CBIR. In terms of STL,the proposed 2D matrix based indexing minimizes the computationeffort for retrieving similar images and for LTL, the proposed algorithmtakes minimum log information than the existing approaches.
基金Project(2022YFB3807404)supported by the National Key Research and Development Program of ChinaProject(52302158)supported by the National Natural Science Foundation of China。
文摘Piezocatalysis and pyrocatalysis can achieve catalytic action with the application of external mechanical energy and varying temperatures.These catalytic processes have been widely applied in various fields,providing innovative solutions to issues such as water pollution,energy shortages,and global warming.Despite the continuous breakthroughs in the catalytic performance of piezocatalysts and pyrocatalysts,powder-based catalysts face significant limitations due to their inability to be retrieved and the risk of secondary pollution,severely restricting their application.Methods such as compression molding,3 D printing,and the preparation of ceramic-polymer bulk composites can effectively address the issue of catalyst retrievability.However,bulk catalysts,which lose a significant amount of surface area,still need their catalytic performance further enhanced.Therefore,achieving piezocatalysts and pyrocatalysts with excellent catalytic performance and retrievability is of increasing importance.
基金supported by Chinese Research Project under Grant No. 973-2007CB411807China Postdoctoral Science Foundation Funded Project No. 20070420070the Special Fund of China Postdoctoral Science Foundation
文摘To retrieve sea-surface salinity (SSS) from radiometer data at 1.4 GHz, auxiliary data of sea-surface temperature (SST), surface roughness and meteorological variables are needed. The authors study oceanic passive polarimetric microwave remote sensing using 1.4 GHz and 10.7 GHz bands. A set of algorithms are developed for 1.4 GHz and 10.7 GHz microwave polarimetric radiometer at 50° incidence angle to retrieve wind vector, as well as other geophysical parameters, such as SSS, SST, atmospheric volumes of water vapor and liquid water. Idealized retrievals are conducted using 2 324 simulated brightness temperatures of full Stokes parameters at 1.4 GHz and 10.7 GHz. Results indicate that SSS, SST, sea-surface wind speed, direction, atmospheric volumes of water vapor and liquid water can be inversed at the same time. This suggests an alternative way for SSS remote sensing.
文摘大语言模型(LLMs,Large Language Models)具有极强的自然语言理解和复杂问题求解能力,本文基于大语言模型构建了矿物问答系统,以高效地获取矿物知识。该系统首先从互联网资源获取矿物数据,清洗后将矿物数据结构化为矿物文档和问答对;将矿物文档经过格式转换和建立索引后转化为矿物知识库,用于检索增强大语言模型生成,问答对用于微调大语言模型。使用矿物知识库检索增强大语言模型生成时,采用先召回再精排的两级检索模式,以获得更好的大语言模型生成结果。矿物大语言模型微调采用了主流的低秩适配(Low-Rank Adaption,LoRA)方法,以较少的训练参数获得了与全参微调性能相当的效果,节省了计算资源。实验结果表明,基于检索增强生成的大语言模型的矿物问答系统能以较高的准确率快捷地获取矿物知识。
