With a recently constructed composite quasar spectrum and the χ<SUP>2</SUP> minimization technique, we describe a general method for estimating the photometric redshifts of a large sample of quasars by de...With a recently constructed composite quasar spectrum and the χ<SUP>2</SUP> minimization technique, we describe a general method for estimating the photometric redshifts of a large sample of quasars by deriving theoretical color-redshift relations and comparing the theoretical colors with the observed ones. We estimated the photometric redshifts from the 5-band SDSS photometric data of 18678 quasars in the first major data release of SDSS and compared them with their spectroscopic redshifts. The difference is less than 0.1 for 47 % of the quasars and less than 0.2 for 68 %. Based on the calculation of the theoretical color-color diagrams of stars, galaxies and quasars both on the SDSS system and on the BATC system, we expect that we would be able to select candidates of high redshift quasars more efficaciously with the latter than with the former, provided the BATC survey can detect objects with magnitudes fainter than 21.展开更多
Survey lines are important features on the dental meshes for removable partial denture frameworks design, but few researche has been done by surveying digital models. This article describes a method for identifying su...Survey lines are important features on the dental meshes for removable partial denture frameworks design, but few researche has been done by surveying digital models. This article describes a method for identifying survey line on dental meshes and displays survey line in real time. At the beginning, we segment tooth based on morphologic operators to get the tooth parts. The second step is to calculate the viewing direction perpendicular to the occlusal plane. Finally, we extract boundary points on 2D plane, thereby obtaining a survey line in the surveying direction. We have developed a module to demonstrate survey line in real time.展开更多
The complex geological conditions in doubly complex areas tend to result in difficult surface survey operations and poor target layer imaging in the subsurface which has a great impact on seismic data quality. In this...The complex geological conditions in doubly complex areas tend to result in difficult surface survey operations and poor target layer imaging in the subsurface which has a great impact on seismic data quality. In this paper, we propose an optimal crooked line survey method for decreasing the surface survey operational difficulties and improving the sub-layer event continuity. The method concentrates on the surface shooting conditions, first, selecting the proper shot positions based on the specific surface topographic features to reduce the shot difficulties and then optimizing the receiver positioning to meet the prerequisite that the subsurface reflection points remain in a straight line. Using this method cannot only lower the shooting difficulty of rough surface condition areas but also overcome the subsurface reflection point bending problem appearing in the traditional crooked line survey method. On the other hand, we use local infill shooting rather than conventional overall infill shooting to improve sublayer event continuity and uniformity with lower survey operation cost. A model has been calculated and processed with the proposed optimal crooked line survey and local infill shooting design method workflow and the results show that this new method can work for seismic surveys in double complex areas.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘With a recently constructed composite quasar spectrum and the χ<SUP>2</SUP> minimization technique, we describe a general method for estimating the photometric redshifts of a large sample of quasars by deriving theoretical color-redshift relations and comparing the theoretical colors with the observed ones. We estimated the photometric redshifts from the 5-band SDSS photometric data of 18678 quasars in the first major data release of SDSS and compared them with their spectroscopic redshifts. The difference is less than 0.1 for 47 % of the quasars and less than 0.2 for 68 %. Based on the calculation of the theoretical color-color diagrams of stars, galaxies and quasars both on the SDSS system and on the BATC system, we expect that we would be able to select candidates of high redshift quasars more efficaciously with the latter than with the former, provided the BATC survey can detect objects with magnitudes fainter than 21.
文摘Survey lines are important features on the dental meshes for removable partial denture frameworks design, but few researche has been done by surveying digital models. This article describes a method for identifying survey line on dental meshes and displays survey line in real time. At the beginning, we segment tooth based on morphologic operators to get the tooth parts. The second step is to calculate the viewing direction perpendicular to the occlusal plane. Finally, we extract boundary points on 2D plane, thereby obtaining a survey line in the surveying direction. We have developed a module to demonstrate survey line in real time.
基金funded by the National Basic Research program of China(973 Program)(No.2009CB219403)Applied Basic Research Project of CNPC(No:2011B-3706)School Fund of SWPU,and Earth Exploration and Information Technology of Sichuan Provincial Key Disciplines Construction Program
文摘The complex geological conditions in doubly complex areas tend to result in difficult surface survey operations and poor target layer imaging in the subsurface which has a great impact on seismic data quality. In this paper, we propose an optimal crooked line survey method for decreasing the surface survey operational difficulties and improving the sub-layer event continuity. The method concentrates on the surface shooting conditions, first, selecting the proper shot positions based on the specific surface topographic features to reduce the shot difficulties and then optimizing the receiver positioning to meet the prerequisite that the subsurface reflection points remain in a straight line. Using this method cannot only lower the shooting difficulty of rough surface condition areas but also overcome the subsurface reflection point bending problem appearing in the traditional crooked line survey method. On the other hand, we use local infill shooting rather than conventional overall infill shooting to improve sublayer event continuity and uniformity with lower survey operation cost. A model has been calculated and processed with the proposed optimal crooked line survey and local infill shooting design method workflow and the results show that this new method can work for seismic surveys in double complex areas.
