A method of correlation analysis to determine the correlation between two too-short arcs is presented to monitor geosynchro- nous earth orbit objects on a space-based surveillance system. The necessary condition for a...A method of correlation analysis to determine the correlation between two too-short arcs is presented to monitor geosynchro- nous earth orbit objects on a space-based surveillance system. The necessary condition for a geosynchronous earth orbit object to be observed by a space-based visible sensor in two successive orbital periods is derived, and the principle for the selection of search fence parameters is proposed. The processing procedure of the correlation analysis for the two too-short arcs as well as two correlation judgment methods is given and the selection of the threshold value for the judgment is analyzed. Finally, a simulation is performed to demonstrate the applicability of the presented methods. Simulation results ir^dicate that a surveil- lance system can acquire two observation arcs in two successive orbital periods by selecting the suitable search fence parame- ters, and that the two correlation judgment methods and the selected threshold are valid. The initial orbit of the uncorrelated objects can be determined by two observation arcs, and the accuracy of the initial orbit meets the requirements of re-acquiring the object.展开更多
The energies, geometries and harmonic vibrational frequencies of 1 ： 1 5-hydroxytryptamine-water （5-HT-H20） complexes are studied at the MP2/6-311 ＋ ＋ G（d,p） level. Natural bond orbital （NBO）, quantum theory ...The energies, geometries and harmonic vibrational frequencies of 1 ： 1 5-hydroxytryptamine-water （5-HT-H20） complexes are studied at the MP2/6-311 ＋ ＋ G（d,p） level. Natural bond orbital （NBO）, quantum theory of atoms in molecules （QTAIM） analyses and the localized molecular orbital energy decomposition analysis （LMO-EDA） were performed to explore the nature of the hydrogen-bonding interactions in these complexes. Various types of hydro- gen bonds （H-bonds） are formed in these 5-HT-H20 complexes. The intermolecular C4H55HT＇＂Ow H-bond in HTW3 is strengthened due to the cooperativity, whereas no such cooperativity is found in the other 5-HT-H20 complexes. H-bond in which nitrogen atom of amino in 5-HT acted as proton donors was stronger than other H-bonds. Our researches show that the hydrogen bonding interaction plays a vital role on the relative stabilities of 5-HT-H20 complexes.展开更多
It is commonly believed that orbital an-gular momentum(OAM)multiplexing is only suitable for short-range communications in line-of-sight(LoS)scenario and multipath propagation would be detrimental for OAM communicatio...It is commonly believed that orbital an-gular momentum(OAM)multiplexing is only suitable for short-range communications in line-of-sight(LoS)scenario and multipath propagation would be detrimental for OAM communications.It has been demonstrated very recently that OAM multiplexing could work in rich isotropic multipath environment when the conventional spatial equalization is used for data detection.Moreover,the resulting channel capacity is comparable to that of a conventional multiple-input multiple-output system.Nev-ertheless,the rich isotropic multipath environment is an ideal multipath scenario.In this paper,we investigate the performance of OAM multiplexing in arbitrary multipath environment.Contrary to the common belief,it is shown that multipath can be beneficial for OAM multiplexing in terms of channel capacity.Particularly,the OAM capacity increases with enlarged angular spread of the channel and reaches its maximum when the angular spread is comparable to the divergence angle of the OAM beam.Based on the study,the OAM multiplexing is further investigated for base station(BS)applications.It is shown that OAM based BS antennas are comparable to(or even outperform)the conventional BS antennas in terms of channel capacity.展开更多
文摘A method of correlation analysis to determine the correlation between two too-short arcs is presented to monitor geosynchro- nous earth orbit objects on a space-based surveillance system. The necessary condition for a geosynchronous earth orbit object to be observed by a space-based visible sensor in two successive orbital periods is derived, and the principle for the selection of search fence parameters is proposed. The processing procedure of the correlation analysis for the two too-short arcs as well as two correlation judgment methods is given and the selection of the threshold value for the judgment is analyzed. Finally, a simulation is performed to demonstrate the applicability of the presented methods. Simulation results ir^dicate that a surveil- lance system can acquire two observation arcs in two successive orbital periods by selecting the suitable search fence parame- ters, and that the two correlation judgment methods and the selected threshold are valid. The initial orbit of the uncorrelated objects can be determined by two observation arcs, and the accuracy of the initial orbit meets the requirements of re-acquiring the object.
文摘The energies, geometries and harmonic vibrational frequencies of 1 ： 1 5-hydroxytryptamine-water （5-HT-H20） complexes are studied at the MP2/6-311 ＋ ＋ G（d,p） level. Natural bond orbital （NBO）, quantum theory of atoms in molecules （QTAIM） analyses and the localized molecular orbital energy decomposition analysis （LMO-EDA） were performed to explore the nature of the hydrogen-bonding interactions in these complexes. Various types of hydro- gen bonds （H-bonds） are formed in these 5-HT-H20 complexes. The intermolecular C4H55HT＇＂Ow H-bond in HTW3 is strengthened due to the cooperativity, whereas no such cooperativity is found in the other 5-HT-H20 complexes. H-bond in which nitrogen atom of amino in 5-HT acted as proton donors was stronger than other H-bonds. Our researches show that the hydrogen bonding interaction plays a vital role on the relative stabilities of 5-HT-H20 complexes.
基金This work was supported in part by National Natural Science Foundation of China(No.61801366)Natural Science Foundation of Shaanxi Province(No.2020JM-078)the Innovation Team Research Fund of Shaanxi Province(No.2019TD-013).
文摘It is commonly believed that orbital an-gular momentum(OAM)multiplexing is only suitable for short-range communications in line-of-sight(LoS)scenario and multipath propagation would be detrimental for OAM communications.It has been demonstrated very recently that OAM multiplexing could work in rich isotropic multipath environment when the conventional spatial equalization is used for data detection.Moreover,the resulting channel capacity is comparable to that of a conventional multiple-input multiple-output system.Nev-ertheless,the rich isotropic multipath environment is an ideal multipath scenario.In this paper,we investigate the performance of OAM multiplexing in arbitrary multipath environment.Contrary to the common belief,it is shown that multipath can be beneficial for OAM multiplexing in terms of channel capacity.Particularly,the OAM capacity increases with enlarged angular spread of the channel and reaches its maximum when the angular spread is comparable to the divergence angle of the OAM beam.Based on the study,the OAM multiplexing is further investigated for base station(BS)applications.It is shown that OAM based BS antennas are comparable to(or even outperform)the conventional BS antennas in terms of channel capacity.
