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潘文熙 《暨南大学学报(自然科学与医学版)》1991,(3)
本文建立了正弦级数(S_T)的例子,系数α_n→0,{α_n}∈(?)∩(?),但{α_n}(?),以及指出存在(S_T),α_n→0,{α_n}∈(?),‖S_n-g‖_1→0,但α_nIogn不趋于零。 相似文献
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Falcke H Apel WD Badea AF Bähren L Bekk K Bercuci A Bertaina M Biermann PL Blümer J Bozdog H Brancus IM Buitink S Brüggemann M Buchholz P Butcher H Chiavassa A Daumiller K de Bruyn AG de Vos CM Di Pierro F Doll P Engel R Gemmeke H Ghia PL Glasstetter R Grupen C Haungs A Heck D Hörandel JR Horneffer A Huege T Kampert KH Kant GW Klein U Kolotaev Y Koopman Y Krömer O Kuijpers J Lafebre S Maier G Mathes HJ Mayer HJ Milke J Mitrica B Morello C Navarra G Nehls S Nigl A Obenland R Oehlschläger J 《Nature》2005,435(7040):313-316
The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10(20) eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within approximately 50 Mpc through interactions with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or gamma-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing. 相似文献
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本文较深入地研究了脱硫石膏粉煤灰化学成分、杂质、颗粒特征和激发剂等对脱硫石膏、粉煤灰胶结材性能的影响 研究表明 ,激发剂是影响脱硫石膏、粉煤灰胶结材性能的主要因素 这为脱硫石膏、粉煤灰资源化利用打下良好理论基础 经实际应用表明 ,研究结果与实际情况能很好相符 相似文献
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介绍用计算机软件产生正弦稳态扫频信号的编程方法。通过对D/A变换与A/D采集的同步输出可以获得不同频率量程和设定电压的扫频输出 相似文献
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一类高阶非线性系统的零解稳定性 总被引:1,自引:0,他引:1
由Барбащин公式得到的四阶常系数线性系统的Ляпунов函数出发,通过类比法构造了一类四阶非线性系统的Ляпунов函数,并由此得到了这些系统零解的全局渐近稳定性的充分条件 相似文献
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