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111.
采用反应离子束溅射和后退火处理技术在石英玻璃基底上制备了具有纳米粒子的二氧化钒(VO2)薄膜. 该薄膜具有半导体-金属相变特性,在3 μm处的开关率达到76.6%。 热致相变实验结果给出了准确的最佳退火温度为465 ℃. 仿真、热致相变和光致相变实验都显示VO2薄膜在红外波段具有很高的光学开关特性. 光电池防护实验结果显示VO2薄膜将硅光电池的抗干扰能力提升了2.6倍, 证明了VO2在激光防护中的适用性. 采用连续可调节系统研究得到VO2在室温条件下的相变阈值功率密度为4.35 W/cm2, 损伤阈值功率密度为404 W/cm2。 低相变阈值和高损伤阈值都进一步证明VO2薄膜适用于激光防护系统。本实验制备的VO2薄膜在光开关、光电存储器、智能窗等方面也具有广泛的应用价值. 相似文献
112.
Graphene oxide (GO) particles in aqueous dispersions can form liquid crystal (LC) phases at extremely low concentrations due to the extremely high aspect ratio of the flakes and noticeably, they possess an extremely large Kerr coefficient attractive for low power consumption electro‐optic devices. Reduced graphene does not easily form LC phases in water due to its hydrophobic nature but here we show that stable dispersions of reduced graphene oxide can be realized with surfactants and that they exhibit birefringence upon shearing as well as under application of electric fields. The performance of the system is largely superior to GO LC possessing longer time stability and drastically improved electro‐optic properties with an induced birefringence twice as large at the same field strength thanks to the almost recovery of graphene properties upon reduction. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
113.
Threshold switching is a phenomenon where the resistivity of an insulating material changes and the insulator exhibits metallic behavior. This could be explained by phase transformation in oxide materials; however, this behavior is also seen in amorphous insulators. In this study, through an ex-situ experiment using transmission electron microscopy (TEM), we proved that threshold switching of amorphous NbO2 accompanies local crystallization. The change in I–V characteristics after electroforming was examined by evaluating the concentration profile. Atom probe tomography (APT) combined with in-situ TEM probing technique was performed to understand the threshold switching in amorphous NbO2. The local crystallization in amorphous NbO2 was validated by the observed difference in time-of-flight (ToF) between amorphous and crystalline NbO2. We concluded that the slower ToF of amorphous NbO2 (a-NbO2) compared with crystalline NbO2 (c-NbO2) is due to the resistivity difference and trap-assisted recombination. 相似文献
114.
针对现有的变结构滑模控制切换面单一性会导致系统状态在原点处收敛缓慢的缺陷,对自主式水下机器人(AUVs)变结构滑模控制设计了折线型的切换面,并且进一步改进实现了速度控制和定点定速控制。改进的切换面由斜率不同的自线段构成,并在拐点处通过S型函数光滑过渡。将切换面的斜率减小到0时,则可以实现速度控制,同时为了消除速度控制的稳态误差,引进了采用能智积分方法的积分项。最后在某AUV上进行仿真实验,结果证实了应用折线型切换面可以减少控制系统的上升时间,提高反应速度;速度控制的稳态误差接近0,并很好地实现定点定速的控制效果。该方法可以有效用于AUVs的控制。 相似文献
115.
模块级联是用于绝缘实验所需的高性能对称双极型矩形波脉冲电源的一种方法,为实现级联,需要有能够协调工作的高隔离度直流电源。设计出嵌入到各电源的板级嵌入式控制器BEC,使各BEC作为从节点利用RS485接口和ModBus协议与嵌入式主控制器EHC构成一个主从式现场总线网络,并在主节点EHC的控制下协调工作。利用BEC内的STM32F103C8处理器产生隔离DC-DC桥的互补PWM控制信号和高隔离输出电压,并进行电流和输出电压的隔离检测。由基于电流切换的变参数增量式数字PI算法来确定脉冲宽度值,产生Buck调压电路的闭环PWM控制信号,实现输出电压的调压和稳压控制。实验结果表明该嵌入式控制器能够满足级联式对称双极型矩形波脉冲电源对高隔离度可调直流电源的需要。 相似文献
116.
Bipolar resistive switching characteristics are investigated in ZrO2 containing Cu thin layer devices, particularly for the self‐isolated‐structure device fabricated by one step lift‐off process. Compared with the traditional‐structure device, the self‐isolated‐structure device shows more uniform resistive switching characteristics. This is because the isolation of each device cell has negligible influence on each other and thus mitigates possible crosstalk between each cell. These results suggest that the feasibility of good stabilization of the resistive switching parameters can be obtained through one step lift‐off process. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
117.
为了解决现有镜面偏心测量设备存在的问题,本文研究了一种采用切换镜头和调焦相结合的方法来设计的镜面偏心测量光学系统,使用这个光学系统,既能使被测镜面的曲率半径扩展到-∞~+∞范围,又能保证测量精度。通过Lighttools软件对这个光学系统进行光线追迹,分析其杂光分布,结果表明:准直镜头内部多次反射产生的杂光强度很低,可以忽略。而当被测镜头中存在相邻球心像距的镜面时,产生的杂光强度比较大,在后续的图像处理过程中,必须增强目标图像的对比度。利用研制的镜面偏心测量设备进行测量实验,结果进一步验证了杂光分析的正确性。 相似文献
118.
《Current Applied Physics》2015,15(9):1005-1009
Forming-free and self-compliant bipolar resistive switching is observed in Cu/TaOx/TiN conductive bridge random access memory. Generally, Pt has been investigated as an inert electrode. However, Pt is not desirable material in current semiconductor industry for mass production. In this study, all electrodes are adapted to complementary metal-oxide-semiconductor compatible materials. The self-compliant resistive switching is achieved via usage of TiN bottom electrode. Also, dissolved Cu ions in TaOx lead to forming-free resistive switching behavior. The resistive switching mechanism is formation and rupture of combined oxygen vacancy/metallic copper conductive filament. We propose that Cu/TaOx/TiN is a promising candidate for a conductive bridge random access memory structure. 相似文献
119.
120.
Simultaneous determination of peroxydisulfate and conventional inorganic anions by ion chromatography with the column‐switching technique
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Zhongping Huang Chengzhu Ni Fengli Wang Zuoyi Zhu Qamar Subhani Muhua Wang Yan Zhu 《Journal of separation science》2014,37(3):198-203
The application of ion chromatography with the column‐switching technique for the simultaneous analysis of peroxydisulfate and conventional inorganic anions in a single run is described. With this method, conventional inorganic anions were separated by consecutive elution through both the guard column and separation column, but peroxydisulfate that only passed through the guard column had a good peak shape and short retention time. A series of standard solutions consisting of target anions of various concentrations from 0.01 to 75 mg/L were analyzed, with a correlation coefficient (r) ≥ 0.9990. The limits of detection were in the range of 0.49–9.84 μg/L based on the S/N of 3 and a 25 μL injection volume. RSDs for retention time, peak area, and peak height were all <1.77%. A spiking study was performed with satisfactory recoveries between 97.6 and 103.4% for all anions. The quantitative determination of peroxydisulfate and conventional inorganic anions in surface waters was accomplished within 18 min by this column‐switching technique. 相似文献