对砝码磁性测量的研究

砝码磁性是递过磁化率和永久极化强度来描述。随着电子天平和高精度电子比较的仪的普及,砝码磁性对砝码检定的影响越来越明显。文章通过磁化率计法测摄砝码磁化率和永久极化强度的研究,提出了使用划分非正圆柱体砝码检定磁化率的实现方法,以指导我们的日常检定工作。     

Achieving High‐Performance Nondoped OLEDs with Extremely Small Efficiency Roll‐Off by Combining Aggregation‐Induced Emission and Thermally Activated Delayed Fluorescence

Luminescent materials with thermally activated delayed fluorescence (TADF) can harvest singlet and triplet excitons to afford high electroluminescence (EL) efficiencies for organic light‐emitting diodes (OLEDs). However, TADF emitters generally have to be dispersed into host matrices to suppress emission quenching and/or exciton annihilation, and most doped OLEDs of TADF emitters encounter a thorny problem of swift efficiency roll‐off as luminance increases. To address this issue, in this study, a new tailor‐made luminogen (dibenzothiophene‐benzoyl‐9,9‐dimethyl‐9,10‐dihydroacridine, DBT‐BZ‐DMAC) with an unsymmetrical structure is synthesized and investigated by crystallography, theoretical calculation, spectroscopies, etc. It shows aggregation‐induced emission, prominent TADF, and interesting mechanoluminescence property. Doped OLEDs of DBT‐BZ‐DMAC show high peak current and external quantum efficiencies of up to 51.7 cd A^?1 and 17.9%, respectively, but the efficiency roll‐off is large at high luminance. High‐performance nondoped OLED is also achieved with neat film of DBT‐BZ‐DMAC, providing excellent maxima EL efficiencies of 43.3 cd A^?1 and 14.2%, negligible current efficiency roll‐off of 0.46%, and external quantum efficiency roll‐off approaching null from peak values to those at 1000 cd m^?2. To the best of the authors' knowledge, this is one of the most efficient nondoped TADF OLEDs with small efficiency roll‐off reported so far.     

A Structurable Gel‐Polymer Electrolyte for Sodium Ion Batteries

In this work, a structurable gel‐polymer electrolyte (SGPE) with a controllable pore structure that is not destroyed after immersion in an electrolyte is produced via a simple nonsolvent induced phase separation (NIPS) method. This study investigates how the regulation of the nonsolvent content affects the evolving nanomorphology of the composite separators and overcomes the drawbacks of conventional separators, such as glass fiber (GF), which has been widely used in sodium ion batteries (SIBs), through the regulation of pore size and gel‐polymer position. The interfacial resistance is reduced through selective positioning of a poly(vinylidene fluoride‐co‐hexa fluoropropylene) (PVdF‐HFP) gel‐polymer with the aid of NIPS, which in turn enhances the compatibility between the electrolyte and electrode. In addition, the highly porous morphology of the GF/SGPE obtained via NIPS allows for the absorption of more liquid electrolyte. Thus, a greatly improved cell performance of the SIBs is observed when a tailored SGPE is incorporated into the GF separator through charge/discharge testing compared with the performance observed with pristine GF and conventional GF coated with PVdF‐HFP gel‐polymer.     

Field‐Induced n‐Doping of Black Phosphorus for CMOS Compatible 2D Logic Electronics with High Electron Mobility

Black phosphorus (BP) has been considered as a promising two‐dimensional (2D) semiconductor beyond graphene owning to its tunable direct bandgap and high carrier mobility. However, the hole‐transport‐dominated characteristic limits the application of BP in versatile electronics. Here, we report a stable and complementary metal oxide semiconductor (COMS) compatible electron doping method for BP, which is realized with the strong field‐induced effect from the K⁺ center of the silicon nitride (Si_xN_y). An obvious change from pristine p‐type BP to n type is observed after the deposit of the Si_xN_y on the BP surface. This electron doping can be kept stable for over 1 month and capable of improving the electron mobility of BP towards as high as ~176 cm² V^–1 s^–1. Moreover, high‐performance in‐plane BP p‐n diode and further logic inverter were realized by utilizing the n‐doping approach. The BP p‐n diode exhibits a high rectifying ratio of ~10⁴. And, a successful transfer of the output voltage from “High” to “Low” with very few voltage loss at various working frequencies were also demonstrated with the constructed BP inverter. Our findings paves the way for the success of COMS compatible technique for BP‐based nanoelectronics.     

28 GHz下对毫米波透射特性的分析

毫米波段拥有高速传输数据的优点,是目前第5代(the 5th Generation,5G)移动通信系统的重要候选频段之一.为了研究毫米波的透射特性,将一对喇叭天线相向放置在玻璃门的两侧,在28 GHz频率下使用800 MHz带宽设备进行了一系列透射特性的测量.研究了不同入射角,极化方式及不同发射端与接收端(Transmitter-Receiver,Tx-Rx)距离对透射系数的影响.将测量结果与菲涅耳传播定律(包括光滑表面和提出的高斯粗糙表面模型)进行了对比.结果表明,文中提出的高斯粗糙表面模型与垂直和水平极化信号的透射特性更拟合.此外,实验也研究了收发端距离对透射的影响,并得出了不同入射角度下的穿透损耗值.     

利用极化方位角特征的高分辨极化SAR目标增强研究

针对高分辨极化SAR目标增强问题,提出一种利用极化方位角特征的增强方法.首先,利用圆极化法提取极化SAR图像像素点的极化方位角特征;其次,通过"方位角归零化"获得像素点在零度极化方位角下的散射矩阵值.对比归零化前、后目标及杂波区域内部像素点极化特性聚集程度的差异,阐述了利用极化方位角特征进行目标增强的原理;再次,统计获得目标及杂波区域的平均极化特性,采用非线性最优化方法实现了目标增强;最后,基于ADTS全极化SAR实测数据验证了本文方法具有优良的目标增强性能.     

一种可免用光隔离器的抗反射同轴激光器TO-CAN

文章提出了一种不用光隔离器即可提高器件抗反射性能的抗反射同轴激光器TO-CAN(晶体管外形封装), 该TO-CAN集成了半导体激光器的电/光信号转换功能和抗反射功能,采用现有的贴片工艺和粘胶工艺,通过在底座TO-Header(晶体管外形头)上面安装激光器芯片、偏振片和λ/4波片而制成,理论分析和实验结果都验证了该方案的有效性和实用性.     

弱场偏振探测技术灵敏度及噪声的定性分析

弱场偏振探测技术是分子取向探测技术的一种。该探测技术不会破坏无外场取向分子的量子状态从而便于取向后的分子进行各种实际应用,因此这种技术在分子取向的研究中运用较为广泛。详细介绍了弱场偏振探测技术和其改进技术——平衡弱场偏振探测技术的探测原理和实验系统组成,以泰勒级数为基础采用近似方法分析、比较了两种探测技术的灵敏度,探讨了二者的噪声来源和影响。研究发现,在分子取向度较小时,后者的灵敏度比前者较强;探测激光能量涨落较大时,后者的噪声明显低于前者;探测激光能量涨落可以忽略时,二者的噪声大小比较接近。     

海面油膜的偏振反射特性仿真实验

为了给海面溢油污染识别检测提供理论基础,根据菲涅尔反射公式的偏振反射系数,结合偏振双向反射率因子和粗糙海面的概率密度分布函数,建立了完善的pBRDF模型,仿真在不同太阳入射角度、不同探测器观测角度以及不同海面风速风向等条件下海水和油膜的偏振反射分布函数。结果表明:海水和油膜太阳天顶角为53°和56°时P偏振反射率分别为1.0×10^-5和2.5×10^-5,S偏振反射率随着太阳天顶角的增加而增加;海面风速越大偏振反射率峰值越小;海面风向只改变pBRDF的空间位置;海水和油膜线偏振度空间分布有明显差异。搭建实验平台相机以40°拍摄时,得出海水和油膜的线偏振度分别在0.2~0.4, 0.5~0.7之间,同时表明利用偏振探测获取目标场景的偏振度和偏振角图可提高图像质量。