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81.
由于TFT-LCD显示屏的物理特性随温度而发生变化,驱动电路必须提供具有相同温度特性的驱动电压,以补偿显示屏的温度特性,进而提高显示画质。文章研究并设计了一种用于TFT-LCD彩屏手机驱动芯片的基准电压产生电路,其输出电压的绝对值与温度系数可编程调节,从而可实现与液晶显示屏的温度特性相匹配。介绍了该电路的各子模块电路,包括偏置电路、带隙基准电路和输出电压调节电路,详细分析了带隙基准电路所产生的基准电压的温度系数及其调节原理。用Hspice对采用0.25μmCMOS工艺设计的电路进行了仿真。仿真结果表明,基准电压的温度系数可从-1.24~1.13mV/℃变化,输出电压的绝对值可从1.8~2.1V调节,最大可提供负载电流40mA。 相似文献
82.
超高亮度LED测量问题 总被引：5，自引：2，他引：5
从原理上讨论了高亮度LED光强测试不确定性大的问题，大多数发光二极管不能被看作点光源，因此实际测量的是平均发光强度，它的测试结果与测试装置结构有关。为解决这个问题，CIE(国际照明委员会)制定并推荐标准测试条件A，B。介绍了根据CIE-127文件设计的平均LED发光强度测试仪；讨论了LED光通量和颜色测量问题，介绍了色温和相关色温测试的方法。对今后的测量和测试标准问题提出了意见。 相似文献
83.
84.
主要介绍广东联通GSM计费集中采集系统，从网络组织和系统软件功能两方面分析探讨了一个完整应用解决方案。 相似文献
85.
张帆 《微电子学与计算机》2013,(10)
由于Lorenz ,Duffing等一些混沌算法结构过于简单并且参数数量较少,应用在信息加密中容易被破译。将Lorenz与Duffing混沌算法相融合,产生一种新的多参数、结构复杂的六维混沌算法。将该混沌算法结合Arnold映射应用于彩色图像加密领域,仿真结果表明该混沌算法加密效果良好。 相似文献
86.
A correlation exists between luminance samples and chrominance samples of a color image. It is beneficial to exploit such interchannel redundancy for color image compression. We propose an algorithm that predicts chrominance components Cb and Cr from the luminance component Y. The prediction model is trained by supervised learning with Laplacian‐regularized least squares to minimize the total prediction error. Kernel principal component analysis mapping, which reduces computational complexity, is implemented on the same point set at both the encoder and decoder to ensure that predictions are identical at both the ends without signaling extra location information. In addition, chrominance subsampling and entropy coding for model parameters are adopted to further reduce the bit rate. Finally, luminance information and model parameters are stored for image reconstruction. Experimental results show the performance superiority of the proposed algorithm over its predecessor and JPEG, and even over JPEG‐XR. The compensation version with the chrominance difference of the proposed algorithm performs close to and even better than JPEG2000 in some cases. 相似文献
87.
The aim of this study was to determine the effect of different drying methods: convective (at 50, 60, 70 °C), vacuum-microwave (at 120, 240, 360, 480 W and 360 W with reduction to 120 W) and hybrid (convective pre-drying at 50, 60, 70 °C followed by vacuum-microwave drying at 120 W) on the quality parameters of novel red-fleshed apple fruit snacks (RFAs), such as phenolics, on-line antioxidant capacity, water activity and color. Drying kinetics, including a temperature profile of dried material, and modified Page model were determined. Freeze-drying was used as a control method. The highest content of bioactive compounds in the samples was retained following freeze-drying, then hybrid, vacuum-microwave and finally convection drying. The antioxidant capacity measured by on-line 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), identified anthocyanins, flavan-3-ols and phenolic acid as the main compounds responsible for this activity. Unfavorable changes in color, formation of hydroxymethylfurfural (HMF) and degradation of polyphenolics were noted along with increasing drying temperature and magnetron power. The red-fleshed apple snacks are a promising high-quality dehydrated food product belonging to functional foods category. 相似文献
88.
Markus Suta Flavie Lavoie‐Cardinal Claudia Wickleder 《Angewandte Chemie (International ed. in English)》2020,59(27):10949-10954
Inorganic hosts, such as SrB4O7 or certain nitrides, intrinsically stabilize Eu2+ even when the dopant is an Eu3+‐based precursor and reducing conditions are not employed in the synthesis. Although this concept is well known in the synthesis of phosphorescent materials, the mechanistic details are scarcely understood. Herein, we demonstrate that trapped charge carriers, such as color centers, can also act as redox partners to stabilize certain oxidation states of activators. Eu‐activated CsMgCl3 and CsMgBr3 are used as examples. Upon doping with EuCl3 and in the absence of reducing conditions during the synthesis, dominant cyan or green luminescence from Eu2+ ions was observed. Photoluminescence spectroscopy at 10 K revealed that the reduction is correlated to color centers localized at defects. Although defects are typically undesired in phosphors, we have shown that their role may be underestimated and they could be used on purpose in the preparation of selected inorganic phosphors. 相似文献
89.
Peter Benner Patrick Kürschner Zoran Tomljanovi&#x; Ninoslav Truhar 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2016,96(5):604-619
We consider the problem of determining an optimal semi‐active damping of vibrating systems. For this damping optimization we use a minimization criterion based on the impulse response energy of the system. The optimization approach yields a large number of Lyapunov equations which have to be solved. In this work, we propose an optimization approach that works with reduced systems which are generated using the parametric dominant pole algorithm. This optimization process is accelerated with a modal approach while the initial parameters for the parametric dominant pole algorithm are chosen in advance using residual bounds. Our approach calculates a satisfactory approximation of the impulse response energy while providing a significant acceleration of the optimization process. Numerical results illustrate the effectiveness of the proposed algorithm. 相似文献
90.
B. Visser M. Beck P. Bornhauser G. Knopp T. Gerber R. Abela J. A. van Bokhoven P. P. Radi 《Journal of Raman spectroscopy : JRS》2016,47(4):425-431
The potential of two‐color resonant and degenerate four‐wave mixing spectroscopy for investigations of the complex spectra of transition metal dimers is explored. Two‐color resonant and degenerate four‐wave mixing spectroscopy scans of the well‐known A‐X and B‐X transitions in Cu2 are reported and compared with previous experimental data obtained from standard single‐resonance techniques. The selectivity of the method is shown to enable the measurement of isotopologue pure spectra without the need for isotopically enriched metal targets. Specific subsets of the rovibronic structure are separated in a congested spectral region of overlapping transitions. The sensitivity of the method compares satisfactorily with linear spectroscopic methods such as laser‐induced fluorescence and cavity ring‐down. A new laser vaporization source for the production of transition metal dimers and clusters has been constructed. The new design aims for a high number density and maximum possible shot‐to‐shot stability. The possibilities of further applications of non‐linear four‐wave mixing spectroscopy to Cu2 and other transition metal dimers are discussed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献