为了实现一维频率扫描,设计了一个X波段的串馈频扫平面阵列天线。单个功分器采用四分支定向耦合器,并且引入低通滤波结构,在实现大功分比设计的同时还解决了两输出口间的相位偏移问题。采用低损耗空气带状线作为馈线,有效降低了串馈频...为了实现一维频率扫描,设计了一个X波段的串馈频扫平面阵列天线。单个功分器采用四分支定向耦合器,并且引入低通滤波结构,在实现大功分比设计的同时还解决了两输出口间的相位偏移问题。采用低损耗空气带状线作为馈线,有效降低了串馈频扫天线的损耗。馈电网络与天线阵列独立设计,降低了对计算机硬件的要求。实测结果表明,所设计阵列可实现-27°~30°的一维扫描,副瓣电平低于-22 d B。展开更多
Gracilaria lemaneiformis Bory is an economically important alga that is primarily used for agar production.Although tetraspores are ideal seeds for the cultivation of G.lemaneiformis,the most popular culture method is...Gracilaria lemaneiformis Bory is an economically important alga that is primarily used for agar production.Although tetraspores are ideal seeds for the cultivation of G.lemaneiformis,the most popular culture method is currently based on vegetative fragments,which is labor-intensive and time-consuming.In this study,we optimized the conditions for tetraspore release and evaluated the photosynthetic activities of different colonies formed from the branches of G.lemaneiformis using a PAM(pulse-amplitude-modulated) measuring system.The results showed that variations in temperature and salinityhad significant effects on tetraspore yield.However,variations in the photon flux density(from 15 μmol m-2 s-1 to 480 μmol m-2 s-1) had no apparent effect on tetraspore yield.Moreover,the PAM-parameters Y(I),Y(Ⅱ),ETR(I),ETR(Ⅱ) and Fv/Fm of colonies formed from different branches showed the same trend:parameter values of first generation branches>second generation branches>third generation branches.These results suggest that the photosynthetic activities of different colonies of branches changed with the same trend.Furthermore,photosynthesis in G.lemaneiformis was found to be involved in vegetative reproduction and tetraspore formation.Finally,the first generation branches grew slowly,but accumulated organic compounds to form large numbers of tetraspores.Taken together,these results showed that the first generation branches are ideal materials for the release of tetraspores.展开更多
We study strong decays of the possible fully-charm tetraquarks recently observed by LHCb,and calculate their relative branching ratios through the Fierz rearrangement.Together with our previous QCD sum rule study,our ...We study strong decays of the possible fully-charm tetraquarks recently observed by LHCb,and calculate their relative branching ratios through the Fierz rearrangement.Together with our previous QCD sum rule study,our results suggest that the broad structure around 6.2–6.8 GeV can be interpreted as an S-wave cccc tetraquark state with JPC=0++or 2++,and the narrow structure around 6.9 GeV can be interpreted as a P-wave one with JPC=0-+or 1-+.These structures were observed in the di-J=w invariant mass spectrum,and we propose to confirm them in the di-gc;J/ψhc;ηcχc0,and ηcχc1channels.We also propose to search for their partner states having the negative charge-conjugation parity in the J/ψηc;J/ψχc0;J/ψχc1,and ηchc channels.展开更多
文摘为了实现一维频率扫描,设计了一个X波段的串馈频扫平面阵列天线。单个功分器采用四分支定向耦合器,并且引入低通滤波结构,在实现大功分比设计的同时还解决了两输出口间的相位偏移问题。采用低损耗空气带状线作为馈线,有效降低了串馈频扫天线的损耗。馈电网络与天线阵列独立设计,降低了对计算机硬件的要求。实测结果表明,所设计阵列可实现-27°~30°的一维扫描,副瓣电平低于-22 d B。
基金Supported by the National Natural Science Foundation of China(No.30830015)the National Key Technology Research and Development Program of the 11th Five-Year Plan(No.2006BAD09A04)the National High Technology Research and Development Program of China(863Program,Nos.2006AA10A402,2007AA09Z406,2006AA05Z112,2006AA10A413)
文摘Gracilaria lemaneiformis Bory is an economically important alga that is primarily used for agar production.Although tetraspores are ideal seeds for the cultivation of G.lemaneiformis,the most popular culture method is currently based on vegetative fragments,which is labor-intensive and time-consuming.In this study,we optimized the conditions for tetraspore release and evaluated the photosynthetic activities of different colonies formed from the branches of G.lemaneiformis using a PAM(pulse-amplitude-modulated) measuring system.The results showed that variations in temperature and salinityhad significant effects on tetraspore yield.However,variations in the photon flux density(from 15 μmol m-2 s-1 to 480 μmol m-2 s-1) had no apparent effect on tetraspore yield.Moreover,the PAM-parameters Y(I),Y(Ⅱ),ETR(I),ETR(Ⅱ) and Fv/Fm of colonies formed from different branches showed the same trend:parameter values of first generation branches>second generation branches>third generation branches.These results suggest that the photosynthetic activities of different colonies of branches changed with the same trend.Furthermore,photosynthesis in G.lemaneiformis was found to be involved in vegetative reproduction and tetraspore formation.Finally,the first generation branches grew slowly,but accumulated organic compounds to form large numbers of tetraspores.Taken together,these results showed that the first generation branches are ideal materials for the release of tetraspores.
基金supported by the National Natural Science Foundation of China (11722540 and 11975033)the Chinese National Youth Thousand Talents Program+2 种基金the China National Funds for Distinguished Young Scientists (11825503)the National Program for Support of Top-notch Young Professionalsthe Fundamental Research Funds for the Central Universities。
文摘We study strong decays of the possible fully-charm tetraquarks recently observed by LHCb,and calculate their relative branching ratios through the Fierz rearrangement.Together with our previous QCD sum rule study,our results suggest that the broad structure around 6.2–6.8 GeV can be interpreted as an S-wave cccc tetraquark state with JPC=0++or 2++,and the narrow structure around 6.9 GeV can be interpreted as a P-wave one with JPC=0-+or 1-+.These structures were observed in the di-J=w invariant mass spectrum,and we propose to confirm them in the di-gc;J/ψhc;ηcχc0,and ηcχc1channels.We also propose to search for their partner states having the negative charge-conjugation parity in the J/ψηc;J/ψχc0;J/ψχc1,and ηchc channels.
