The Wide Field Survey Telescope(WFST)is located at 4200 m on Saishiteng Mountain in Lenghu,Qinghai Province,China.It features a primary mirror with a diameter of 2.5 m and a camera equipped with nine CCDs,providing a ...The Wide Field Survey Telescope(WFST)is located at 4200 m on Saishiteng Mountain in Lenghu,Qinghai Province,China.It features a primary mirror with a diameter of 2.5 m and a camera equipped with nine CCDs,providing a wide field of view of approximately 3×3 square degrees.Calibration parameters are essential to ensure the precision of astrometric observations with the WFST.These parameters are derived from geometric distortion(GD)and gaps through astrometric modeling and are subsequently validated via the Yao’An High Precision Telescope(YAHPT).The GD solutions show maximum distortions between 1.18 and 10.29 pixels for the WFST chips,with central chips exhibiting lower distortion.After applying the GD correction,the precision of the WFST reaches 4 mas.The interchip gaps of the WFST range from 1.922 mm to 7.765 mm,corresponding to 10μm/pixel,aligning with the design and measurements.The calibrated parameters guarantee that the WFST can perform highly accurate astrometric measurements.Furthermore,as the WFST undergoes updates,the parameter model remains consistently applicable.展开更多
With the advances of display technology, three-dimensional(3-D) imaging systems are becoming increasingly popular. One way of stimulating 3-D perception is to use stereo pairs, a pair of images of the same scene acqui...With the advances of display technology, three-dimensional(3-D) imaging systems are becoming increasingly popular. One way of stimulating 3-D perception is to use stereo pairs, a pair of images of the same scene acquired from different perspectives. Since there is an inherent redundancy between the images of a stereo pairs, data compression algorithms should be employed to represent stereo pairs efficiently. The proposed techniques generally use block-based disparity compensation. In order to get the higher compression ratio, this paper employs the wavelet-based mixed-resolution coding technique to incorporate with SPT-based disparity-compensation to compress the stereo image data. The mixed-resolution coding is a perceptually justified technique that is achieved by presenting one eye with a low-resolution image and the other with a high-resolution image. Psychophysical experiments show that the stereo image pairs with one high-resolution image and one low-resolution image provide almost the same stereo depth to that of a stereo image with two high-resolution images. By combining the mixed-resolution coding and SPT-based disparity-compensation techniques, one reference (left) high-resolution image can be compressed by a hierarchical wavelet transform followed by vector quantization and Huffman encoder. After two level wavelet decompositions, for the low-resolution right image and low-resolution left image, subspace projection technique using the fixed block size disparity compensation estimation is used. At the decoder, the low-resolution right subimage is estimated using the disparity from the low-resolution left subimage. A full-size reconstruction is obtained by upsampling a factor of 4 and reconstructing with the synthesis low pass filter. Finally, experimental results are presented, which show that our scheme achieves a PSNR gain (about 0.92dB) as compared to the current block-based disparity compensation coding techniques.展开更多
Nowadays, many kinds of computer network data management systems have been built widely in China. People have realized widely that management information system (MIS) has brought a revolution to the management mechani...Nowadays, many kinds of computer network data management systems have been built widely in China. People have realized widely that management information system (MIS) has brought a revolution to the management mechanism. Moreover, the managers of company need wide-range and comprehensive decision information more and more urgently which is the character of information explosion era. The needs of users become harsher and harsher in the design of MIS, and these needs have brought new problems to the general designers of MIS. Furthermore, the current method of traditional database development can't solve so big and complex problems of wide-range and comprehensive information processing. This paper proposes the adoption of parallel processing mode, the built of new decision support system (DSS) is to discuss and analyze the problems of information collection, processing and the acquirement of full-merit information with cross-domain and cross-VLDB (very-large database).展开更多
In solving the clustering problem in the context of knowledge discovery in databases (KDD), the traditional methods, for example, the K-means algorithm and its variants, usually require the users to provide the number...In solving the clustering problem in the context of knowledge discovery in databases (KDD), the traditional methods, for example, the K-means algorithm and its variants, usually require the users to provide the number of clusters in advance based on the pro-information. Unfortunately, the number of clusters in general is unknown to the users who are usually short of pro-information. Therefore, the clustering calculation becomes a tedious trial-and-error work, and the result is often not global optimal especially when the number of clusters is large. In this paper, a new dynamic clustering method based on genetic algorithms (GA) is proposed and applied for auto-clustering of data entities in large databases. The algorithm can automatically cluster the data according to their similarities and find the exact number of clusters. Experiment results indicate that the method is of global optimization by dynamically clustering logic.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA0350300)the National Natural Science Foundation of China(12203105,12103091,62394351,12073008)the China Manned Space Project(CMS-CSST-2021-A12,CMS-CSST-2021-B10).
文摘The Wide Field Survey Telescope(WFST)is located at 4200 m on Saishiteng Mountain in Lenghu,Qinghai Province,China.It features a primary mirror with a diameter of 2.5 m and a camera equipped with nine CCDs,providing a wide field of view of approximately 3×3 square degrees.Calibration parameters are essential to ensure the precision of astrometric observations with the WFST.These parameters are derived from geometric distortion(GD)and gaps through astrometric modeling and are subsequently validated via the Yao’An High Precision Telescope(YAHPT).The GD solutions show maximum distortions between 1.18 and 10.29 pixels for the WFST chips,with central chips exhibiting lower distortion.After applying the GD correction,the precision of the WFST reaches 4 mas.The interchip gaps of the WFST range from 1.922 mm to 7.765 mm,corresponding to 10μm/pixel,aligning with the design and measurements.The calibrated parameters guarantee that the WFST can perform highly accurate astrometric measurements.Furthermore,as the WFST undergoes updates,the parameter model remains consistently applicable.
基金This project was supported by the National Natural Science Foundation (No. 69972027).
文摘With the advances of display technology, three-dimensional(3-D) imaging systems are becoming increasingly popular. One way of stimulating 3-D perception is to use stereo pairs, a pair of images of the same scene acquired from different perspectives. Since there is an inherent redundancy between the images of a stereo pairs, data compression algorithms should be employed to represent stereo pairs efficiently. The proposed techniques generally use block-based disparity compensation. In order to get the higher compression ratio, this paper employs the wavelet-based mixed-resolution coding technique to incorporate with SPT-based disparity-compensation to compress the stereo image data. The mixed-resolution coding is a perceptually justified technique that is achieved by presenting one eye with a low-resolution image and the other with a high-resolution image. Psychophysical experiments show that the stereo image pairs with one high-resolution image and one low-resolution image provide almost the same stereo depth to that of a stereo image with two high-resolution images. By combining the mixed-resolution coding and SPT-based disparity-compensation techniques, one reference (left) high-resolution image can be compressed by a hierarchical wavelet transform followed by vector quantization and Huffman encoder. After two level wavelet decompositions, for the low-resolution right image and low-resolution left image, subspace projection technique using the fixed block size disparity compensation estimation is used. At the decoder, the low-resolution right subimage is estimated using the disparity from the low-resolution left subimage. A full-size reconstruction is obtained by upsampling a factor of 4 and reconstructing with the synthesis low pass filter. Finally, experimental results are presented, which show that our scheme achieves a PSNR gain (about 0.92dB) as compared to the current block-based disparity compensation coding techniques.
文摘Nowadays, many kinds of computer network data management systems have been built widely in China. People have realized widely that management information system (MIS) has brought a revolution to the management mechanism. Moreover, the managers of company need wide-range and comprehensive decision information more and more urgently which is the character of information explosion era. The needs of users become harsher and harsher in the design of MIS, and these needs have brought new problems to the general designers of MIS. Furthermore, the current method of traditional database development can't solve so big and complex problems of wide-range and comprehensive information processing. This paper proposes the adoption of parallel processing mode, the built of new decision support system (DSS) is to discuss and analyze the problems of information collection, processing and the acquirement of full-merit information with cross-domain and cross-VLDB (very-large database).
基金This project was supported by the National Natural Science Foundation of China (No. 79400013, No. 60074026).
文摘In solving the clustering problem in the context of knowledge discovery in databases (KDD), the traditional methods, for example, the K-means algorithm and its variants, usually require the users to provide the number of clusters in advance based on the pro-information. Unfortunately, the number of clusters in general is unknown to the users who are usually short of pro-information. Therefore, the clustering calculation becomes a tedious trial-and-error work, and the result is often not global optimal especially when the number of clusters is large. In this paper, a new dynamic clustering method based on genetic algorithms (GA) is proposed and applied for auto-clustering of data entities in large databases. The algorithm can automatically cluster the data according to their similarities and find the exact number of clusters. Experiment results indicate that the method is of global optimization by dynamically clustering logic.
