MEMS矢量水听器的一种新的联合去噪算法

针对传感器水声信号存在随机噪声的问题,提出了一种正余弦算法(SCA)和粒子群算法(PSO)相结合优化变分模态分解(VMD)参数κ和α,将含噪信号通过VMD分解为k个固有模态函数,选取相关系数高的模态分量进行小波阈值(WT)去噪后重构信号分量,得到目标信号的算法,记为SCA-PSO-VMD-WT算法.通过将本算法与VMD...     

亚100 nm应变Si/SiGe nMOSFET阈值电压二维解析模型

本文基于二维泊松方程,建立了适用于亚100 nm应变Si/SiGe nMOSFET的阈值电压理论模型.为了保证该模型的准确性,同时考虑了器件尺寸减小所导致的物理效应,如短沟道效应,量子化效应等.通过将模型的计算结果与二维器件模拟器ISE的仿真结果进行对比分析,证明了本文提出的模型的正确性.最后,还讨论了亚100 nm器件中常规工艺对阈值电压的影响.该模型为亚100 nm小尺寸应变Si器件的分析设计提供了一定的参考. 关键词： 亚100nm 应变Si/SiGe nMOSFET 二维表面势 阈值电压     

On minimal nonscattering solution for focusing mass-subcritical nonlinear Schrödinger equation

We consider time global behavior of solutions to the focusing mass-subcritical NLS equation in a weighted L² space. We prove that there exists a threshold solution such that (i) it does not scatter; (ii) with respect to a certain scale-invariant quantity, this solution attains minimum value in all nonscattering solutions. In the mass-critical case, it is known that ground states are this kind of threshold solution. However, in our case, it turns out that the above threshold solution is not a standing wave solution.     

时频结合自适应阈值小波包消噪算法

在充分考虑人耳听觉特性和噪声统计特性的基础上,提出一种时频结合Bark尺度自适应阈值的语音消噪算法,在Bark频域上自适应调整增强系数可以较准确地进行阈值判定。仿真实验验证,时频结合算法在低信噪比输入情况下较传统语音降噪方法具有明显优势,其在消除高斯白噪声的同时有效降低了语音损失,可获得最大信噪比,谱失真测度最小,增强语音的MOS(Mean Opinion Score)评分明显提高,具有较好的听觉效果。     

Random lasing from dye-doped negative liquid crystals using ZnO nanoparticles as tunable scatters

This work demonstrates the realization of a lasing in scattering media,which contains dispersive solution of Zn O nanoparticles(NPs) and laser dye 4-dicyanomethylene-2-methyle-6-(p-dimethylaminostyryl)-4H-pyran(DCM) in negative liquid crystals(LCs) that was injected into a cell.The lasing intensity of the dye-doped negative LC laser can be tuned from low to high if the NPs concentration is increased.The tunability of the laser is attributable to the clusters-sensitive feature in effective refractive index of the negative LCs.Such a tunable negative liquid crystal laser can be used in the fabrication of new optical sources,optical communication,and liquid crystal laser displays.     

KDP晶体的杂质与光学性能分析

 测量常规方法与快速方法生长的非线性光学KDP晶体紫外及近红外波段透射光谱性能,并测定了晶体不同生长区域杂质的含量,通过对实验结果的分析比较讨论了影响晶体紫外透过性能的因素;采用多脉冲平均方式测量了不同方法生长晶体在1 064nm及532 nm皮秒激光脉冲作用下的晶体损伤阈值,晶体的体吸收系数与晶体抗损伤能力的对应关系表明晶体内部的杂质与缺陷存在着明显的光吸收, 从而降低了晶体对高能量脉冲的负载能力。     

低温低剂量率下金属-氧化物-半导体器件的辐照效应

对金属氧化物半导体(MOS)器件在低剂量率γ射线辐照条件下的剂量率效应以及温度效应进行了研究.对不同剂量率、不同温度辐照后MOS器件的阈值电压漂移进行了比较.结果表明,低剂量率辐照下,感生界面态要受到辐照时间的长短以及生成的氢离子数目的影响,辐照时间越长,生成的氢离子越多,感生界面态密度越大;温度对界面态的影响与界面态建立的时间有关,低温辐照时,界面态建立的时间要加长 关键词： 辐照效应 阈值电压漂移 低剂量率 低温 界面态     

SiC肖特基源漏MOSFET的阈值电压

SiC肖特基源漏MOSFET的阈值电压不同于传统的MOSFET的阈值电压.在深入分析工作机理的基础上,利用二维模拟软件ISE提取并分析了器件的阈值电压.对SiC肖特基源漏MOSFET的阈值电压给出物理描述,得出当源极载流子主要以场发射方式进入沟道,同时沟道进入强反型状态,此时的栅电压是该器件的阈值电压. 关键词： 碳化硅 肖特基接触 阈值电压     

High temperature annealing effect on structure, optical property and laser-induced damage threshold of Ta2O5 films

Ta₂O₅ films were deposited by conventional electron beam evaporation method and then annealed in air at different temperature from 873 to 1273 K. It was found that the film structure changed from amorphous phase to hexagonal phase when annealed at 1073 K, then transformed to orthorhombic phase after annealed at 1273 K. The transmittance was improved after annealed at 873 K, and it decreased as the annealing temperature increased further. The total integrated scattering (TIS) tests and AFM results showed that both scattering and root mean square (RMS) roughness of films increased with the annealing temperature increasing. X-ray photoelectron spectroscopy (XPS) analysis showed that the film obtained better stoichiometry and the O/Ta ratio increased to 2.50 after annealing. It was found that the laser-induced damage threshold (LIDT) increased to the maximum when annealed at 873 K, while it decreased when the annealing temperature increased further. Detailed damaged models dominated by different parameters during annealing were discussed.     

溶胶-凝胶法制备高折射率TiO2薄膜

 采用溶胶- 凝胶法制备了TiO₂纳米晶溶胶,并以旋涂法（spin-coating）镀制了高折射率光学薄膜。借助光散射技术和透射电镜研究了溶胶的微结构。采用原子力显微镜、场发射扫描电镜、紫外-可见-近红外光谱仪、椭偏仪、漫反射吸收光谱及强激光辐照实验,对膜层的结构、光学性能及抗激光损伤性能进行了系统的表征。结果显示:纳米晶薄膜的折射率达到了1.9,而传统的溶胶-凝胶薄膜折射率只有1.6;同时纳米晶薄膜的抗激光损伤阈值与传统的溶胶-凝胶薄膜相差不大,在1 064 nm处分别为16.3 J/cm²(3 ns脉冲) 和16.6 J/cm²(3 ns脉冲);纳米晶溶胶薄膜可以在保持较高抗激光损伤阈值情况下,大幅度提高薄膜折射率。