In core logging, each joint set intersects borehole into some segments. In this research, it has been shown that length of the borehole segments created by each joint set could be computed by trigonometrical relations...In core logging, each joint set intersects borehole into some segments. In this research, it has been shown that length of the borehole segments created by each joint set could be computed by trigonometrical relations. By realizing the lengths associated with joint sets, an algorithm has been designed to compute the length of borehole pieces (created by all joint sets) and to calculate RQD. Effect of some factors have been analyzed and applied to the abstract model of the rock mass to have the most similarity to a real rock mass. The program proposed in this study, is a robust platform to calculate the RQD in all directions inside a rock mass without having to deal with the labor of core logging and wrestling with difficulties and inaccuracies of the traditional processes. This is the first algorithmic method for estimating the rock quality which could be employed to develop a new and far more reliable measurement for the degree of jointing inside a rock mass.展开更多
In view of the requirements of Tianwen-1 missions on precision orbit determination and scientific application,this paper proposes a high-precision open-loop velocity measurement method based on ground-based radio.At f...In view of the requirements of Tianwen-1 missions on precision orbit determination and scientific application,this paper proposes a high-precision open-loop velocity measurement method based on ground-based radio.At first,relying on space–ground TT&C resources of the Tianwen-1 probe,the paper designs an open-loop velocity measurement strategy based on China’s deep-space network.Then,it proposes a core algorithm of open-loop velocity measurement based on local cross-correlation reconstruction to obtain instantaneous Doppler frequency observables.This algorithm is characterized by a high ability to avoid phase lock loss,convenient and efficient implementation,and flexible parameter configuration and is suitable for high-precision velocity measurement in the case of high dynamics and low signal-to-noise ratios.On this basis,the similarity and difference of velocity observables between open-loop and baseband velocity measurements are analyzed comparatively.Finally,on the basis of the open-loop velocity measurement method,the paper carries out tests on high precision orbit determination with independent support of velocity measurement,as well as on Mars radio occultation.According to the research results,the accuracy of open-loop velocity measurement can reach 0.05 mm/s(in 1-s integration time),which is 2 to 3 times better than that of baseband velocity measurement.Open-loop velocity measurement can independently support orbit determination accuracy of 50 m of the Tianwen-1 probe and effectively support autonomous retrieval of Martian ionospheric electron density profiles.Thus,this method can be effectively applied to future missions of deep-space exploration and research of planetary radio science.展开更多
文摘In core logging, each joint set intersects borehole into some segments. In this research, it has been shown that length of the borehole segments created by each joint set could be computed by trigonometrical relations. By realizing the lengths associated with joint sets, an algorithm has been designed to compute the length of borehole pieces (created by all joint sets) and to calculate RQD. Effect of some factors have been analyzed and applied to the abstract model of the rock mass to have the most similarity to a real rock mass. The program proposed in this study, is a robust platform to calculate the RQD in all directions inside a rock mass without having to deal with the labor of core logging and wrestling with difficulties and inaccuracies of the traditional processes. This is the first algorithmic method for estimating the rock quality which could be employed to develop a new and far more reliable measurement for the degree of jointing inside a rock mass.
基金supported by the National Natural Science Foundation of China(nos.11973015 and 12373082)Civil Aerospace Research Project of China(no.D020309)National Key Laboratory of Aerospace Flight Dynamics(no.KGJ6142210220106).
文摘In view of the requirements of Tianwen-1 missions on precision orbit determination and scientific application,this paper proposes a high-precision open-loop velocity measurement method based on ground-based radio.At first,relying on space–ground TT&C resources of the Tianwen-1 probe,the paper designs an open-loop velocity measurement strategy based on China’s deep-space network.Then,it proposes a core algorithm of open-loop velocity measurement based on local cross-correlation reconstruction to obtain instantaneous Doppler frequency observables.This algorithm is characterized by a high ability to avoid phase lock loss,convenient and efficient implementation,and flexible parameter configuration and is suitable for high-precision velocity measurement in the case of high dynamics and low signal-to-noise ratios.On this basis,the similarity and difference of velocity observables between open-loop and baseband velocity measurements are analyzed comparatively.Finally,on the basis of the open-loop velocity measurement method,the paper carries out tests on high precision orbit determination with independent support of velocity measurement,as well as on Mars radio occultation.According to the research results,the accuracy of open-loop velocity measurement can reach 0.05 mm/s(in 1-s integration time),which is 2 to 3 times better than that of baseband velocity measurement.Open-loop velocity measurement can independently support orbit determination accuracy of 50 m of the Tianwen-1 probe and effectively support autonomous retrieval of Martian ionospheric electron density profiles.Thus,this method can be effectively applied to future missions of deep-space exploration and research of planetary radio science.
