红外热像仪参数测量装置的仪器常数模型研究

在红外热像仪的参数测量过程中,由于辐射温差在传输过程中受到测量系统各单元的光学反射率以及大气传输等的影响,热像仪实际接收到的辐射温差并非目标的原始温差.通过对辐射能量传输的分析,提出了双黑体参数测量装置"仪器常数"的概念并对其进行了建模仿真,此模型可以在测量中减小由辐射温差传递带来的误差,从而提高了双黑体参数测量装置的测量准确度.     

基于辐射定标的某型红外光纤传像束双波段透过率测定

由于目前国内尚没有针对红外光纤传像束的波段透过率测试的规范标准和设备。提出了一种考虑光纤孔径角和光纤芯径的热像仪定标方法和某型光纤传像束的双波段透过率测试方法。通过在冷屏两端分别设置直径为8 mm和62 μm的两个光阑孔,确保定标条件和所测光纤的孔径角和光纤芯径相同;再通过在光路中插入波段滤光片来选择需要定标的波段。建立了基于最小二乘的红外热像仪定标模型,并采用该方法进行了定标实验。根据定标结果,测量了某型光纤传像束的红外光纤在2.0 μm～2.6 μm波段和3.4 μm～4.8 μm波段的透过率,其平均透过率大于70%。     

基于生成对抗网络的动态心电信号QRS波检测

心电信号分析是预防心血管疾病的重要举措,QRS波的精确检测不仅是心电信号处理的关键步骤且对心率计算和异常情况分析具有重要作用.针对动态心电信号存在信号质量差或异常节奏波形导致常用QRS波检测方法精度较低的问题,本文提出了 一种基于生成对抗网络新型QRS波检测算法.该算法以Pix2Pix网络为基础,生成网络采用U-Net...     

几种主流视频编码方式的性能比较和分析

随着多媒体通信技术的不断发展,不同的组织提出了许多不同特点的编码方法。文中回顾并分析了当前一些主流的编码机制,通过峰值信噪比(PSNR)和最小察觉差(JND)对主流视频编码技术的质量性能进行了比较。通过比较发现,使用客观的PSNR标准时,H．264/AVC的各方面性能要好于现在使用的视频压缩标准,但选择主观的JND标准可能会略微影响不同编码的性能。     

激光大气传输透射原理及应用

分析了激光大气传输时的衰减过程,介绍了几种情况下的大气散射透射率.以典型的1.06μm激光为例,详细推导了其经大气吸收和散射后的透过率,在此基础上举例说明了运用激光透射规律所设计的一些装置及其应用.     

基于高斯插值提高雷达测距精度的研究

本文结合脉冲法雷达测距原理,分析了距离量化误差产生的原因.针对LFM信号加入高斯白噪声作脉冲压缩得到的脉压波形,结合先验信息,将脉压结果主瓣内的波形近似为高斯分布,利用脉压结果中采样最大值点和次大值点的位置信息和幅度信息作高斯插值处理,预估脉压波形真实峰值时间.仿真结果表明,通过高斯插值处理,距离量化误差显著减小,雷达...     

Blue-phase liquid crystal display with high dielectric material

A blue-phase liquid crystal display (BPLCD) with low operating voltage and high transmittance is demonstrated by using a high dielectric material, which is used as an insulation layer or protrusion fixed on the pixel and common electrodes in in-plane switching (IPS) mode. The operating voltage is reduced to about 14 V and the transmittance is improved for the BPLCD with high dielectric constant protrusion. Compared with the conventional protrusion electrode structure, the proposed protrusion can make manufacturing process simple and easy because the electrode has no complex shape. The results will be significant in designing optimal BPLCDs.     

Highly transparent cerium doped gadolinium gallium aluminum garnet ceramic prepared with precursors fabricated by ultrasonic enhanced chemical co-precipitation

Cerium doped gadolinium gallium aluminum garnet (GGAG:Ce) ceramic precursors have been synthesized with an ultrasonic chemical co-precipitation method (UCC) and for comparison with a traditional chemical co-precipitation method (TCC). The effect of ultra-sonication on the morphology of powders and the transmittance of GGAG:Ce ceramics are studied. The results indicate that the UCC method can effectively improve the homogenization and sinterability of GGAG:Ce powders, which contribute to obtain high transparent GGAG ceramic with the highest transmittance of 81%.     

Electro-photo modulation of the fermi level in WSe2/graphene van der Waals heterojunction

We report an electro-photo double modulation of the fermi level in a WSe₂/graphene heterojunction. The heterojunction exhibits high I_ON/I_OFF ratio (~10³) in transfer characteristic in dark and distinct rectification behavior in output characteristic under light illumination, respectively. Time-dependent photoresponse reveals that the heterojunction has a considerable potential in the application of photodetection. Interestingly, an exotic current peak is observed in transfer characteristic under light illumination. This novel behavior is attributed to the tunable fermi level at the WSe₂/graphene heterojunction by electro-photo double modulation. The results may be helpful to develop tunable photovoltaic optoelectronics based on van der Waals heterojunctions.