Only in the presence of sidelobe jamming （SLJ）, can the conventional adaptive monopulse technique null the jamming effectively and maintain the monopulse angle estimation accuracy simultaneously. While mainlobe jamm...Only in the presence of sidelobe jamming （SLJ）, can the conventional adaptive monopulse technique null the jamming effectively and maintain the monopulse angle estimation accuracy simultaneously. While mainlobe jamming （MLJ） exists, the mainlobe of adaptive pattern will subject to serious distortion, which results in a failure of detecting and tracking targets by monopulse technique. Therefore, a monopulse angle estimation algorithm based on combining sum-difference beam and auxiliary beam is presented. This algorithm utilizes both high gain difference beams and high gain auxiliary beams for cancelling the mainlobe jammer and multiple sidelobe jammers （SLJs） while keeping an adap- tive monopulse ratio. Theoretical analysis and simulation results indicate that the serious invalidation of monopulse technique in MLJ and SLJs scenarios is resolved well, which improves the monopulse angle accuracy greatly. Furthermore, the proposed algorithm is of simple implementation and low computational complexity.展开更多
Beryllium(Be)is one of the unsubstitutable key metals in strategic emerging industries and national defense industries,mainly originating from volcanogenic Be deposits.Thus,volcanogenic Be deposits have become importa...Beryllium(Be)is one of the unsubstitutable key metals in strategic emerging industries and national defense industries,mainly originating from volcanogenic Be deposits.Thus,volcanogenic Be deposits have become important research objects of key metal deposits,with a focus on their occurrence,metallogenic mechanism,and resource distribution.In the southeast coast of China,the Late Mesozoic volcanic intrusive complex has a good Be metallogenic background,and strong Be mineralization occurs in some areas.Field geological investigation and analyses of samples from Southeast Zhejiang as well as Northeast and Southeast Fujian indicate that Be mineralization in the southeast coast of China is closely related to the hydrothermal processes in the volcanic intrusive complex.In Southeast Zhejiang,Be ore in the Qingtian area mainly occurs in granite porphyry,with the Be content reaching 939 ppm,while strong Be mineralization from Zhangji rhyolite porphyry in the Pingyang area contains up to 11400 ppm Be.In Xiapu County,Northeastern Fujian,the Dawan Be deposit is characterized by constituents of helvite and beryl.In Pinghe County,Southeastern Fujian,the Fulishi Be ore is a quartz vein beryl-type ore.These results suggest that the volcanic intrusive complex area in the southeast coast of China has a wide range of Be mineralization and better Be metallogenic potential,and it is expected to become an important Be metallogenic belt in China.Thus,we should thoroughly investigate the Be resources of granite porphyry,rhyolite porphyry,quartz porphyry,and quartz vein in this volcanic rock area,which can provide a theoretical basis for the exploration and guiding prospecting of volcanic intrusive complex Be deposits.展开更多
The discovery of superconductivity at Tc = 26 K in fluorine-doped LaFeAsO [1] has led to the subsequent findings of dozens of new superconducting materials in the class of Fe-based superconductors (FeSCs)[2,3]. All th...The discovery of superconductivity at Tc = 26 K in fluorine-doped LaFeAsO [1] has led to the subsequent findings of dozens of new superconducting materials in the class of Fe-based superconductors (FeSCs)[2,3]. All those FeSCs were found to possess antifluorite-like Fe2X2 (X = As, Se) layers which were believed to be the crucial structural motif for the emergence of high-temperature superconductivity. This common feature makes it possible to design a new FeSC with the crystal chemistry [3-5]. For example, with the consideration of the intergrowth of BaFe2As2 and BaTi2As2O, the new FeSC Ba2Fe2Ti2As4O (Tc=21 K) was discovered [6]. The block-layer-design approach was also demonstrated to be effective for other class of layered materials, such as Eu3Bi2S4F4 [7], LaPb- BiS3O [8], La5Cu4As4O4C12 [9], Pb5BiFe3O10Cl2 [10], and Bi4Q4CU1.7Se2.7CI03 [11].展开更多
基金supported by the National Natural Science Foundation of China(60925005)
文摘Only in the presence of sidelobe jamming （SLJ）, can the conventional adaptive monopulse technique null the jamming effectively and maintain the monopulse angle estimation accuracy simultaneously. While mainlobe jamming （MLJ） exists, the mainlobe of adaptive pattern will subject to serious distortion, which results in a failure of detecting and tracking targets by monopulse technique. Therefore, a monopulse angle estimation algorithm based on combining sum-difference beam and auxiliary beam is presented. This algorithm utilizes both high gain difference beams and high gain auxiliary beams for cancelling the mainlobe jammer and multiple sidelobe jammers （SLJs） while keeping an adap- tive monopulse ratio. Theoretical analysis and simulation results indicate that the serious invalidation of monopulse technique in MLJ and SLJs scenarios is resolved well, which improves the monopulse angle accuracy greatly. Furthermore, the proposed algorithm is of simple implementation and low computational complexity.
基金supported by the Major Research Plan of the National Natural Science Foundation of China(Grant No.92062212)the Key Deployment Project of Institute of Geology and Geophysics,Chinese Academy of Sciences(Grant No.IGGCAS-201902)。
文摘Beryllium(Be)is one of the unsubstitutable key metals in strategic emerging industries and national defense industries,mainly originating from volcanogenic Be deposits.Thus,volcanogenic Be deposits have become important research objects of key metal deposits,with a focus on their occurrence,metallogenic mechanism,and resource distribution.In the southeast coast of China,the Late Mesozoic volcanic intrusive complex has a good Be metallogenic background,and strong Be mineralization occurs in some areas.Field geological investigation and analyses of samples from Southeast Zhejiang as well as Northeast and Southeast Fujian indicate that Be mineralization in the southeast coast of China is closely related to the hydrothermal processes in the volcanic intrusive complex.In Southeast Zhejiang,Be ore in the Qingtian area mainly occurs in granite porphyry,with the Be content reaching 939 ppm,while strong Be mineralization from Zhangji rhyolite porphyry in the Pingyang area contains up to 11400 ppm Be.In Xiapu County,Northeastern Fujian,the Dawan Be deposit is characterized by constituents of helvite and beryl.In Pinghe County,Southeastern Fujian,the Fulishi Be ore is a quartz vein beryl-type ore.These results suggest that the volcanic intrusive complex area in the southeast coast of China has a wide range of Be mineralization and better Be metallogenic potential,and it is expected to become an important Be metallogenic belt in China.Thus,we should thoroughly investigate the Be resources of granite porphyry,rhyolite porphyry,quartz porphyry,and quartz vein in this volcanic rock area,which can provide a theoretical basis for the exploration and guiding prospecting of volcanic intrusive complex Be deposits.
基金supported by the National Key Research and Development Program of China(2017YFA0303002)the Fundamental Research Funds for the Central Universities of China(2019FZA3004)
文摘The discovery of superconductivity at Tc = 26 K in fluorine-doped LaFeAsO [1] has led to the subsequent findings of dozens of new superconducting materials in the class of Fe-based superconductors (FeSCs)[2,3]. All those FeSCs were found to possess antifluorite-like Fe2X2 (X = As, Se) layers which were believed to be the crucial structural motif for the emergence of high-temperature superconductivity. This common feature makes it possible to design a new FeSC with the crystal chemistry [3-5]. For example, with the consideration of the intergrowth of BaFe2As2 and BaTi2As2O, the new FeSC Ba2Fe2Ti2As4O (Tc=21 K) was discovered [6]. The block-layer-design approach was also demonstrated to be effective for other class of layered materials, such as Eu3Bi2S4F4 [7], LaPb- BiS3O [8], La5Cu4As4O4C12 [9], Pb5BiFe3O10Cl2 [10], and Bi4Q4CU1.7Se2.7CI03 [11].
