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提出了一种基于模糊统计归一化处理(FSNP)的K分布混响形状参数自适应估计方法。该方法首先对混响进行归一化处理,然后对不同归一化处理强度的处理数据进行形状参数估计,最后,取适中归一化处理强度数据形状参数估计值作为最终估计值。仿真结果表明,所提方法在参杂干扰背景和均匀背景下,都具有很好的参数估计性能。实测带宽4000 Hz声呐同区域混响参数估计结果显示,混响参杂强干扰时,所提方法形状参数估计值的最小值、最大值、标准差、极差分别为1.13,25.76, 4.36, 24.63,混响均匀时分别为2.54, 20.78, 3.84, 18.24。相比于传统抑制干扰和均匀背景参数估计算法,无论是同区域参杂干扰混响,还是均匀混响,所提方法参数估计结果的标准差和极差都明显下降。 相似文献
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突发公共事件网络舆情是信息时代背景下比较重要的传播现象,在网络社交媒体不断发展的背景下,突发公共事件由于突发性、破坏性、公共性等特点引发的网络舆情也日益增加。突发公共事件网络舆情具有群体极化、标签效应、蝴蝶效应等特点,在进行网络舆情引导时往往需要结合其具体的效应特点,进行综合分析和讨论。面对突发公共事件舆情,需要主动进... 相似文献
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锐钛矿型TiO2水溶胶的低温制备及其表征 总被引:7,自引:0,他引:7
Anatase titanium dioxide hydrosol was prepared at low temperature by a simple method. The title material was characterized by TEM, XRD, FTIR and BET, respectively. The photocatalytic activity of the as-prepared TiO2 was evaluated by the degradation of methyl orange solution under sunlight and the photocatalytic oxidation of acetone in air. The results showed that the titanium dioxide hydrosol was composed of anatase phase with average grain size of about 7 nm, and the crystallinity became more perfect with the increase of temperature. The BET surface areas were more than 220 m2·g-1 for these samples. It is found that the photocatalytic activity was much better for the higher heat processing temperature. Especially, the photocatalytic activity of the sample with a heat treatment of 110 ℃ was better than that of P25. In addition, TiO2 hydrosol also possessed good photocatalytic activity under the sunlight illumination. 相似文献
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We grew a series of NaFe1-xVx As(0 ≤ x ≤ 0.03) single crystals and performed the measurements of resistance,magnetic susceptibility, and specific heat to study the superconducting phase diagram by doping V into Na Fe As. Both the structural and the spin-density-wave(SDW) transitions are slightly suppressed by V-doping. While superconducting transition temperature is enhanced to the maximum value of 15 K when the optimal doping level x = 0.007 and then is suppressed rapidly with further V-doping, displaying a small superconducting dome. Our results suggest that V-impurities should act as strong magnetic scattering centers which cause the sharp suppression of superconductivity in NaFe1-xVx As. 相似文献
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以硝酸银为银源、聚乙烯吡咯烷酮(PVP)为形貌导向剂、硫酸铁为诱导剂、葡萄糖为还原剂,采用高效便捷的水热法制备银纳米线(AgNWs),通过调控PVP用量和热处理时间致使其长径比大于1000;将异丙醇与乙醇按照一定比例混合,配制出分散性良好的AgNWs墨水,并采用变速旋涂法在玻璃衬底上制备透明导电薄膜;通过低温低压烧结和聚乙烯醇(PVA)固化处理优化薄膜的光学及导电性能,制得方块电阻为(19±2)Ω·sq-1、透过率大于86;透明导电薄膜. 相似文献
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<正>哈佛大学有一门课叫积极心理学(也翻译为幸福课),讲师本·沙哈尔用短短23节课的时间,告诉他的学生们:积极对待生活,才能获得幸福。幸福课在哈佛引起了前所未有的轰动,并成为哈佛最受欢迎的选修课,其网络视频在全球也深受追捧和喜爱。其倡导的理论和越来越多的证据表明,幸福并非是靠努力工作或幸运就能得到,幸福最眷顾的,是那些活在当下的人。 相似文献