With the exceptional sensitivity of the Five-hundred-meter Aperture Spherical radio Telescope,we conducted observations of the neutral hydrogen(HⅠ)in the circumgalactic medium of Andromeda’s(M31)satellite galaxies,s...With the exceptional sensitivity of the Five-hundred-meter Aperture Spherical radio Telescope,we conducted observations of the neutral hydrogen(HⅠ)in the circumgalactic medium of Andromeda’s(M31)satellite galaxies,specifically AndromedaⅡ,NGC 205,and NGC 185.Initially,three drift scans were executed for these satellites,with a detection limit of 4×10^(18)cm^(-2)(approximately 1.88×10^(3)M_Θof HⅠmass),followed by a more in-depth scan of a specific region.We discovered a C-shaped HⅠarc structure sharing a position and line-of-sight velocity similar to a stellar ring structure around AndromedaⅡ,hinting at a potential connection with AndromedaⅡ.In the context of NGC 205,we identified two mass concentrations in the northeast direction,which could be indicative of tidal streams resulting from the interaction between this galaxy and M31.These new lumps discovered could be very helpful in solving the missing interstellar medium problem for NGC 205.Observations regarding NGC 185are consistent with previous studies,and we did not detect any additional HⅠmaterial around this galaxy.These observational results enhance our understanding of the evolution of these satellite galaxies and provide insight into their historical interactions with the galaxy M31.展开更多
This paper outlined a Non-Orthogonal Multiple Access (NOMA) grouping transmission scheme for cognitive radio networks. To address the problems of small channel gain difference of the middle part users caused by the tr...This paper outlined a Non-Orthogonal Multiple Access (NOMA) grouping transmission scheme for cognitive radio networks. To address the problems of small channel gain difference of the middle part users caused by the traditional far-near pairing algorithm, and the low transmission rate of the traditional Orthogonal Multiple Access (OMA) transmission, a joint pairing algorithm was proposed, which provided multiple pairing schemes according to the actual scene. Firstly, the secondary users were sorted according to their channel gain, and then different secondary user groups were divided, and the far-near pairing combined with (Uniform Channel Gain Difference (UCGD) algorithm was used to group the secondary users. After completing the user pairing, the power allocation problem was solved. Finally, the simulation data results showed that the proposed algorithm can effectively improve the system transmission rate.展开更多
我国新一代厘米—分米波日像仪(Chinese Spectral Radio Heliograph,CSRH)已经进入了试观测调试阶段,设备误差修正、试观测数据的处理成为当前CSRH的重要工作。其中,有效地保存与快速处理试观测数据是数据处理的前提。在调研当前国内外...我国新一代厘米—分米波日像仪(Chinese Spectral Radio Heliograph,CSRH)已经进入了试观测调试阶段,设备误差修正、试观测数据的处理成为当前CSRH的重要工作。其中,有效地保存与快速处理试观测数据是数据处理的前提。在调研当前国内外射电干涉观测设备的基础上,深入分析了Aips++、CASA等当前主流射电天方数据处理软件对数据格式的支持情况,分析了射电天文领域的随机组(UVFITS)格式,给出了满足射电日像仪数据的随机组格式。实验表明,所生成的UVFITS文件可以被主流软件正确处理。对CSRH的研制起到了较好的推动作用,也对国内正在开展的其它大型射电观测数据存储有参考价值。展开更多
基金support of the China National Key Program for Science and Technology Research and Development of China(2022YFA1602901)the National Natural Science Foundation of China(NSFC,Grant Nos.11988101 and 11873051)+3 种基金the CAS Project for Young Scientists in Basic Research grant(No.YSBR-062)the K.C.Wong Education Foundationthe science research grants from the China Manned Space Projectsupport from the Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CAS。
文摘With the exceptional sensitivity of the Five-hundred-meter Aperture Spherical radio Telescope,we conducted observations of the neutral hydrogen(HⅠ)in the circumgalactic medium of Andromeda’s(M31)satellite galaxies,specifically AndromedaⅡ,NGC 205,and NGC 185.Initially,three drift scans were executed for these satellites,with a detection limit of 4×10^(18)cm^(-2)(approximately 1.88×10^(3)M_Θof HⅠmass),followed by a more in-depth scan of a specific region.We discovered a C-shaped HⅠarc structure sharing a position and line-of-sight velocity similar to a stellar ring structure around AndromedaⅡ,hinting at a potential connection with AndromedaⅡ.In the context of NGC 205,we identified two mass concentrations in the northeast direction,which could be indicative of tidal streams resulting from the interaction between this galaxy and M31.These new lumps discovered could be very helpful in solving the missing interstellar medium problem for NGC 205.Observations regarding NGC 185are consistent with previous studies,and we did not detect any additional HⅠmaterial around this galaxy.These observational results enhance our understanding of the evolution of these satellite galaxies and provide insight into their historical interactions with the galaxy M31.
文摘This paper outlined a Non-Orthogonal Multiple Access (NOMA) grouping transmission scheme for cognitive radio networks. To address the problems of small channel gain difference of the middle part users caused by the traditional far-near pairing algorithm, and the low transmission rate of the traditional Orthogonal Multiple Access (OMA) transmission, a joint pairing algorithm was proposed, which provided multiple pairing schemes according to the actual scene. Firstly, the secondary users were sorted according to their channel gain, and then different secondary user groups were divided, and the far-near pairing combined with (Uniform Channel Gain Difference (UCGD) algorithm was used to group the secondary users. After completing the user pairing, the power allocation problem was solved. Finally, the simulation data results showed that the proposed algorithm can effectively improve the system transmission rate.
文摘我国新一代厘米—分米波日像仪(Chinese Spectral Radio Heliograph,CSRH)已经进入了试观测调试阶段,设备误差修正、试观测数据的处理成为当前CSRH的重要工作。其中,有效地保存与快速处理试观测数据是数据处理的前提。在调研当前国内外射电干涉观测设备的基础上,深入分析了Aips++、CASA等当前主流射电天方数据处理软件对数据格式的支持情况,分析了射电天文领域的随机组(UVFITS)格式,给出了满足射电日像仪数据的随机组格式。实验表明,所生成的UVFITS文件可以被主流软件正确处理。对CSRH的研制起到了较好的推动作用,也对国内正在开展的其它大型射电观测数据存储有参考价值。
