随着卫星共视时间比对方法的广泛应用,国际频率咨询委员会(Consultative Committee for Time and Frequency,CCTF)发布了扩展的时间传递标准(Common GNSS Generic Time Transfer Standard Version2E,CGGTTS V2E),同时国内外产生了各种...随着卫星共视时间比对方法的广泛应用,国际频率咨询委员会(Consultative Committee for Time and Frequency,CCTF)发布了扩展的时间传递标准(Common GNSS Generic Time Transfer Standard Version2E,CGGTTS V2E),同时国内外产生了各种数据处理软件来生成全球卫星导航时间传递标准(Common GNSS Generic Time Transfer Standard,CGGTTS)文件,对此类软件的性能评估已成为时间传递领域的需求。为此对比利时皇家天文台开发的R2CGGTTS开展GNSS时间传递数据生成性能分析研究,通过接收机单站验证和双站比对试验,分析检验不同系统频点CGGTTS时差数据生成的一致性和稳定性等性能指标。结果表明,R2CGGTTS生成GNSS时间传递数据的均值差可控制在亚纳秒量级,且频率稳定度可达到10-15量级,可见由R2CGGTTS生成的GNSS时间传递数据在多系统时间传递中的可靠性。展开更多
On the basis of a 5 m plate mill, a 3D rigid-plastic finite element （FE） model was developed to investigate changes of plate plan view patterns during hot rolling process. By analyzing the simulation results of conv...On the basis of a 5 m plate mill, a 3D rigid-plastic finite element （FE） model was developed to investigate changes of plate plan view patterns during hot rolling process. By analyzing the simulation results of conventional rolling processes, it was found that the plate plan view pattern was closely related to broadside rolling ratio. Then, the prediction models for plate plan view patterns were formulated by nonlinear regressive analysis of the simulation results and modified for high accuracy. Based on these models, the broadside compensation rolling method perform- ing at the last pass of broadside rolling phase was designed to decrease plate end crops. Comparing the plate plan view patterns with and without broadside compensation roiling, reduced plate end crops indicate that the broadside compensation roiling model is effective for plate plan view pattern control.展开更多
For high precision calibration of camera with large field-of-view,massive calibration points will be needed if traditional methods are selected,which makes the calibration complex and time-consuming.In order to solve ...For high precision calibration of camera with large field-of-view,massive calibration points will be needed if traditional methods are selected,which makes the calibration complex and time-consuming.In order to solve this problem,a calibration method based on flexible planar target is proposed.In this method,distortion factor is firstly acquired by the invariance of cross ratio,and existing feature points are adjusted with the distortion factor.Then,a large number of points that will be used for the calibration are constructed with the adjusted feature points.Simultaneously,Tsai method is modified so as to reduce the complexity of calibration,which makes the process linear.The simulation and real experiments show that the method proposed in this paper is simple,linear,accurate and robust,and the precision of this method is close to that of Tsai method using abundant points.The method can satisfy the requirement of high precision calibration for camera with large field-of-view.展开更多
A new type of philosophy from the view of pansystems is introducedhere,including the 7 philosophy theories(7PT),fuzziness research andmany second/third philosophies are developed within pansystems frame-work.
文摘随着卫星共视时间比对方法的广泛应用,国际频率咨询委员会(Consultative Committee for Time and Frequency,CCTF)发布了扩展的时间传递标准(Common GNSS Generic Time Transfer Standard Version2E,CGGTTS V2E),同时国内外产生了各种数据处理软件来生成全球卫星导航时间传递标准(Common GNSS Generic Time Transfer Standard,CGGTTS)文件,对此类软件的性能评估已成为时间传递领域的需求。为此对比利时皇家天文台开发的R2CGGTTS开展GNSS时间传递数据生成性能分析研究,通过接收机单站验证和双站比对试验,分析检验不同系统频点CGGTTS时差数据生成的一致性和稳定性等性能指标。结果表明,R2CGGTTS生成GNSS时间传递数据的均值差可控制在亚纳秒量级,且频率稳定度可达到10-15量级,可见由R2CGGTTS生成的GNSS时间传递数据在多系统时间传递中的可靠性。
文摘On the basis of a 5 m plate mill, a 3D rigid-plastic finite element （FE） model was developed to investigate changes of plate plan view patterns during hot rolling process. By analyzing the simulation results of conventional rolling processes, it was found that the plate plan view pattern was closely related to broadside rolling ratio. Then, the prediction models for plate plan view patterns were formulated by nonlinear regressive analysis of the simulation results and modified for high accuracy. Based on these models, the broadside compensation rolling method perform- ing at the last pass of broadside rolling phase was designed to decrease plate end crops. Comparing the plate plan view patterns with and without broadside compensation roiling, reduced plate end crops indicate that the broadside compensation roiling model is effective for plate plan view pattern control.
基金Sponsored by the Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.2014019)
文摘For high precision calibration of camera with large field-of-view,massive calibration points will be needed if traditional methods are selected,which makes the calibration complex and time-consuming.In order to solve this problem,a calibration method based on flexible planar target is proposed.In this method,distortion factor is firstly acquired by the invariance of cross ratio,and existing feature points are adjusted with the distortion factor.Then,a large number of points that will be used for the calibration are constructed with the adjusted feature points.Simultaneously,Tsai method is modified so as to reduce the complexity of calibration,which makes the process linear.The simulation and real experiments show that the method proposed in this paper is simple,linear,accurate and robust,and the precision of this method is close to that of Tsai method using abundant points.The method can satisfy the requirement of high precision calibration for camera with large field-of-view.
文摘A new type of philosophy from the view of pansystems is introducedhere,including the 7 philosophy theories(7PT),fuzziness research andmany second/third philosophies are developed within pansystems frame-work.
