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Matched Bearing Processing for Airborne Source Localization by an Underwater Horizontal Line Array
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Location of an airborne source is estimated from signals measured by a horizontal line array (HLA), based on the fact that a signal transmitted by an airborne source will reach a underwater hydrophone in different ways: via a direct refracted path, via one or more bottom and surface reflections, via the so-called lateral wave. As a result, when an HLA near the airborne source is used for beamforming, several peaks at different bearing angles will appear. By matching the experimental beamforming outputs with the predicted outputs for all source locations, the most likely location is the one which gives minimum difference. An experiment is conducted for airborne source localization in the Yellow Sea in October 2008. An HLA was laid on the sea bottom at the depth of 30m. A high-power loudspeaker was hung on a research ship floating near the HLA and sent out LFM pulses. The estimated location of the loudspeaker is in agreement well with the GPS measurements. 相似文献
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Two new one-dimensional chain-like coordination polymers,[Cu(H2O)(dpa)- MoO4]·H2O 1 and [Co(H2O)(dpa)MoO4] 2,have been synthesized under hydrothermal reactions. Their structures were determined by single-crystal X-ray diffraction analysis. Crystal data for 1: [Cu(H2O)(dpa)MoO4]·H2O,Mr = 430.71,monoclinic,space group P21/c,a = 9.5469(10),b = 16.6874(17),c = 9.0799(10)A,β = 104.9100(10)°,V = 1397.8(3)A^3,Z = 4,Dc = 2.047 g/cm^3,F(000) = 852,μ = 2.449 mm-1,the final R = 0.0293 and wR = 0.0638 for 2472 independent reflections (Rint = 0.0338) and 2034 observed reflections with I 〉 2σ(I). Crystal data for 2: [Co- (H2O)(dpa)MoO4],Mr = 408.09,monoclinic,space group P21/c,a = 10.204(2),b = 18.933(4),c = 6.8875(16)A,β = 102.195(3)o,Z = 4,V = 1300.5(5)A^3,Z = 4,Dc = 2.084 g/cm3,F(000) = 804,μ = 2.262 mm-1,the final R = 0.0357 and wR = 0.0693 for 3022 independent reflections (Rint = 0.0436) and 2286 observed reflections (I 〉 2σ(I)). Polymer 1 is based on a one-dimensional zigzag chain built up from {Cu(H2O)(dpa)}2+ units bridged through the bidentate {MoO4}2- ligands. The chains extending along the c-axis are arranged alternately with two opposite orientations along the b-axis. The adjacent chains are stably packed together through π-π interactions and exhibit an interesting three-dimensional supramolecular architecture via hydrogen bonding interactions. Polymer 2 based on a one-dimensional zonal chain is built up from {Co(H2O)(dpa)}2+ units linked by the tridentate {MoO4}2- ligands. The ribbons extend along the c-axis. In the bc layers,there are significant interactions of N-H…O-Mo hydrogen bonds and π-π overlaps of dpa ligands between adjacent ribbons. 相似文献
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一些物理学家预言在大约10^9V/m的电场中,在室温条件下水可以结成冰,他们认为电场引起结晶所需的有序的氢键的形成,如今,在韩国首尔国立大学的Heon Kang实验室首次观察到了这种结冰现象,研究者们在室温和比预期低得多的电场强度(10^6V/m)下使水结成了冰,研究人员认为探索新的冻结机制将有助于了解在各种自然环境下冰的形成。 相似文献
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“斯普鲁恩斯”级导弹驱逐舰从1967年开始进行概念没计,1972年11月,首舰“斯普鲁恩斯”号开工建造,1973年11月下水,1975年9月建成服役。到1983年5月,该级舰共31艘全部完工服役。1980财政年度价的造价为每艘3.9亿美元。原型舰以反潜为主,其后美国海军为适应现代海战要求,先后对其进行了一系列重要改装,加装了多型先进的武器装备和垂商发射系统,使之成为一级反潜、反舰、对地和防空能力都很强的驱逐舰。 相似文献
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印度是二次世界大战以后亚洲第一个拥有航母的国家.印度的第一艘航空母舰是“维克兰特”号(舷号R11),它是20世纪50年代后期从英国购进的“尊严”级轻型航母.印度购买后,对其进行了大幅改装.该舰于1943年10月12日开工,1945年9月22日下水,1961年3月4日服役,1997年1月退役。 相似文献