Research on the prediction of absorption half-band width of some azobenzene compounds

In order to predict the absorption half-band width, the ground state and the first singlet-excited state configurations of some azobenzene compounds are calculated by B3LYP/6-311G* and CIS methods, respectively. Based on the configurations obtained above, the absorption maximum and emission maximum are calculated by TD-DFT method, the results are in good agreement with observed values. Further study shows a linear relationship between Δλ_1/2 (the observed absorption half-band width) and S (the difference between the emission maximum and absorption maximum). According to the relationship obtained, the absorption half-band width of other azobenzene derivatives in the same series could be predicted successfully.     

基于扁平结构元素的指纹脊检测

本文在介绍指纹特征提取的基础上,分析了灰度指纹图像脊检测的特点,提出了一种利用数学形态中的扁平结构元素检测灰度指纹图像中脊的方法,并对这种方法的性能进行了分析,与传统算法相比,在达到同等检测效果的情况下,其运算效率提高了约40％。     

组合形变对三角形脊波导传输特性的影响

脊波导的传输特性包括截止波长、单模带宽、衰减常数、功率容量以及特性阻抗。脊波导器件在装配使用中所产生的错位形变与边侧形变很难单独发生,因此,有必要研究错位形变、底部形变、单侧形变、双侧形变结合的组合形变。利用ANSYS建立模型与MATLAB编写有限元程序相结合的方法计算了三角形脊波导组合形变对其传输特性的影响。研究结果表明,组合形变对三角形脊波导的截止波长、单模带宽影响较小,三边形变与错位底部形变对三角形单脊波导功率容量、衰减常数及特性阻抗影响较大,研究结果将为三角形脊波导的应用提供了理论依据。     

基于峰值电流可调的PWM调光方法减小LED漂移

荧光粉和发光二极管(LED)芯片的发光性质受 电流和结温影响,其变化使白光LED调光时产生 色漂移。通过对白光LED在线性调光和脉冲宽度调制(PWM)调光下色度学参数的 测试分析发现, PWM调光具有更优异的色稳定性;温度升高导致荧光粉转换效率降低;峰值电流增大 致使蓝光与荧 光粉的匹配程度降低。为了进一步降低PWM调光过程中的色漂移,采用峰值电流可调 的PWM调光方 案,当相关色温CCT大于设定值时,可通过降低峰值电流增加占空比的方法 降低CCT,反之则通过增 加峰值电流降低占空比的方法增加CCT。实验结果表明,通过调整峰值电流可补 偿因荧光粉转换效 率变化造成的色漂移,在预设调光范围内的CCT变化小于33 K。对目标 CCT与色稳定范围的关系进行了探讨。     

基于三通道脉冲宽度调制的LED调光调色

为了实现发光二极管(LED)的精确调光,根 据重心原理,结合脉冲宽度调制(PWM),推导出混合光的色品坐标 与占空比的函数关系;采用红/绿/蓝、红/绿/冷白和暖白/绿/蓝3种LED光源模块进行 实验验证,并且 以光效、显色指数和最大光通量3个指标对混光效果进行评价。实验结果表明:建议的计算 模型能精确地指导LED的光 色调节,混合光的色品坐标的设定值和测量值之间的误差小于0.002,色温误差在50 K以内。 用光谱丰富的 冷白和暖白LED分别代替红/绿/蓝光源模块中的蓝光和红光,能提高混合光的显色指数,暖 白/绿/蓝光源模块的混光效果最佳。     

Estimation of high performance in Schmitt triggers with stacking power‐gating techniques in 45 nm CMOS technology

In the complementary metal oxide semiconductor (CMOS) nanoscale technology ground bounce noise and power consumption are becoming important metric. In presented paper, low leakage Schmitt trigger circuits are proposed for wave shaping or cleaning process with low ground bounce noise. Schmitt trigger play important role in communication electronics. Power‐gating and stacking power‐gating techniques have provided for maintaining the parameter of Schmitt trigger. An ideal approach has been investigated with stacking power‐gating technique. For further reduction in peak of ground bounce noise during sleep to active (power) mode transition, we have performed simulations using cadence specter 45 nm standard CMOS technology at nominal temperature (27°C) with supply voltage V_dd = 0.7 V and input voltage vary from 0.7 V to 1.5 V. The simulation results show that a proposed design provide efficient 6 T and 4 T Schmitt triggers in term of minimum leakage power (8.18 fW), active power (17.80 pW), ground bounce noise (1.65 μV) and propagation delay (1.98 ns), transconductance (4.51 × 10^?14 S), voltage gain (29.44 dB), hysteresis width (11.07 V) and efficiency (64.68%). Reported devices use for low‐power communication systems. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental study on the single event effects in pulse width modulators by laser testing

This paper presents single event effect (SEE) characteristics of UC1845AJ pulse width modulators (PWMs) by laser testing. In combination with analysis to map PWM circuitry in the microchip dies, the typical SEE response waveforms for laser pulses located in different circuit blocks of UC1845AJ are obtained and the SEE mechanisms are analyzed. The laser SEE test results show that there are some differences in the SEE mechanisms of different circuit blocks, and phase shifts or changes in the duty cycles of few output pulses are the main SEE behaviors for UC1845AJ. In addition, a new SEE behavior which manifests as changes in the duty cycles of many output pulses is revealed. This means that an SEE hardened design should be considered.     

势阱势垒宽度对GaAs/AlGaAs对称DBS RTD NDR特性的影响

目前共振隧穿二极管(RTD)多值逻辑电路研究采用多个MOSFETs组合,以逼近RTD特性,这是现有逻辑功能验证的不足。针对该问题,通过建立对称双势垒RTD电子输运的解析模型,进而采用SILVACO TCAD对Ga As/Al Ga As基对称DBS RTD器件的电学特性进行仿真实验研究。根据仿真实验的结果分析总结了势阱和势垒宽度对Ga As/Al Ga As基对称DBS RTD负阻特性影响的规律,并根据MVL电路设计应用的低压、低功耗、适当峰谷电流比和工艺可实现性等要求,通过大量的仿真优化实验提出采用Ga As/Al Ga As基对称DBS RTD实现多值逻辑电路设计所需的对称DBS RTD器件设计参数窗口。     

晶体管栅形状对单粒子瞬态脉冲特性的影响研究

通过三维器件模拟仿真,研究了基于CMOS 0.18μm工艺下标准条形栅和环形栅结构MOS晶体管的单粒子瞬态响应.研究结果表明,单粒子轰击条形栅器件与环形栅器件产生的单粒子瞬态脉冲特性具有非常大的区别.分析了栅形状对单粒子瞬态的影响在PMOS和NMOS器件中的不同机理,对单粒子瞬态加固设计具有指导性意义.     

基于脊参数估计的对角加载系数的选取

基于脊回归(Ridge Regression)理论,提出一种对角加载系数的非参数计算方法.通过分析剩余矢量随快拍数变化的趋势,该算法将误差绝对值作为剩余矢量的代价函数.仿真结果表明,新算法在小快拍数据和阵列存在失配时能够抑制噪声带来的旁瓣起伏效应,具有较好的稳健性.