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1.
Deficiencies of the performance-based iterative learning control (ILC) for the non-regular systems are investigated in detail, then a faster control input updating and lifting technique is introduced in the design of performance index based ILCs for the partial non-regular systems. Two ldnds of optimal ILCs based on different performance indices are considered. Finally, simulation examples are given to illustrate the feasibility of the proposed learning controls. 相似文献
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Jin Z Zhang J Yang J Zhong H Qian B Shu T Zhang J Zhou S Xu L 《The Review of scientific instruments》2011,82(8):084704
This paper presents both numerical and experimental studies of a repetitive S-band long-pulse relativistic backward-wave oscillator. The dispersion relation curve of the main slow-wave structure is given by the numerical calculation. Experimental results show that a 1 GW microwaves with pulse duration of about 100 ns (full width of half magnitude) under 10 Hz repetitive operation mode are obtained. The microwave frequency is 3.6 GHz with the dominant mode of TM(01), and power conversion efficiency is about 20%. The single pulse energy is about 100 J. The experimental results are in good agreement with the simulation ones. By analyzing the experimental phenomenon, we obtain the conclusion that the explosive emission on the surface of the electrodynamics structure in intense radio frequency field mainly leads to the earlier unexpected termination of microwave output. 相似文献
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大尺度Co9S8纳米线超声喷雾热解制备 总被引:2,自引:2,他引:0
以CoC l2.6H2O和CS(NH2)2为先驱物,运用超声喷雾热解法在300℃的玻璃衬底上成功地制备了Co9S8纳米线,所得Co9S8纳米线的直径约为500 nm.利用X射线衍射(XRD)、光学显微镜分别对产物的物相和形貌进行了表征,同时讨论了产生大尺度纳米线的软模板机理. 相似文献
5.
基于最小统计噪声估计的信号子空间语音增强 总被引:1,自引:0,他引:1
针对传统子空间方法中,采用语音活动检测(Voice activity detection,VAD)估计噪声的缺陷,提出了一种基于子空间域的最小统计噪声估计算法。噪声估计通过跟踪带噪语音协方差矩阵用每个特征向量上的特征值的最小值来获得,该方法不需要VAD明确区分语音段和噪声段,能够在整个信号期间实现噪声的连续估计和不断更新。实验结果表明,相对于传统的基于VAD的子空间方法,本文提出的算法对语音增强效果有非常显著的提高。 相似文献
6.
CuxS(x=1,2)纳米薄膜的异步脉冲超声喷雾热解法制备 总被引:1,自引:0,他引:1
采用改进的异步脉冲超声喷雾热解技术在玻璃衬底上成功地制备了CuxS(x =1,2 )纳米薄膜 .研究发现 ,所制备的CuxS薄膜为多晶态 ;薄膜的晶相结构依赖于CuCl2 ·2H2 O和硫脲的摩尔比及衬底温度 .XRD和XPS分析表明 :样品为纯CuxS(CuS ,Cu2 S) ,拉曼谱研究表明其峰位分别在 472cm- 1 (Cu2 S)和 474cm- 1 (CuS)处 . 相似文献
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Gaofen-5(GF-5) satellite was successfully launched on May 29, 2018. The Visual and Infrared Multispectral Imager(VIMI) developed independently by China is a multi-spectral imager in the range of visible band to long-wave infrared band, which has broad application prospects. The quality assessment of satellite image is not only the verification of whether the remote sensing satellite meets the design criteria, but also the reference for image processing and application. In this paper, the quality assessment for VIMI is provided, which provides reference for the processing and application of the image. Four indicators, named the Signal-to-Noise Ratio (SNR), clarity, information content and radiation heterogeneity, were used for quality assessment, and were compared with Landsat 8 images. The results show that the SNR of the shortwave infrared band (320.44~388.42) is slightly higher than that of the visible near-infrared band(208.24~238.03). The clarity (0.82~0.91) in the near-shortwave infrared band is higher than that in the other bands, especially in the long-wave infrared band (0.01~0.21). The information content of short-wave infrared band (9.01~9.97) is higher than that of medium-long-wave infrared band (5.71~8.31). The radiation heterogeneity of all 12 bands is less than 2%. The results of comparison with Landsat 8 show that ①the clarity of B1~B4 is better than Landsat 8 and this of other bands are close to Landsat 8,②for information content, B1~B10 of VIMI is close to Landsat 8, while this of B11 and B12 is less than Landsat 8 with 5.23 for B11 and 5.61 for B12,(3)for SNR, GF-5 VIMI still needs to be further improved, with 280.41、226.84 and 151.92 less than Landsat 8 for B1,B2 and B6. 相似文献
8.
以CoCl2·6H2O和硫脲CS(NH2)2为前驱物,利用超声喷雾热解法在300℃玻璃衬底上制备了Co9S8的纳米球壳.运用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)对产物进行了物相和形貌分析,结果表明:产物为直径约500nm,形状相似但不规则的Co9S8球壳.同时,对其生长机理进行了初步研究. 相似文献
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Shengyue Gu Shouyang Zhang Fei Liu Wei Li 《Journal of the European Ceramic Society》2018,38(15):5082-5091
Y2Hf2O7 possesses low thermal conductivity and high melting point, which make it promising for a new anti-ablation material. For evaluating the thermal stability and the potential applications of Y2Hf2O7 on anti-ablation protection of C/C composites, Y2Hf2O7 ceramic powder was synthesized by solution combustion method and Y2Hf2O7 coating was prepared on the surface of SiC coated C/C composites using SAPS. Results shown that the coating exhibits good ablation resistance under the heat flux of 2.4?MW/m2 with the linear and mass ablation rates are 0.16?μm?s?1 and ?0.028?mg?s?1, respectively, after ablation for 40?s. With the prolonging of the ablation time, the increasing thermal stress causes the increase of cracks. Moreover, the chemical erosion from SiO2 and the physical volatilization of low temperature molten products aggravate failure of the Y2Hf2O7 coating. 相似文献