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.     

Cooperative load-balancing strategy based on N-hops routing algorithm of ad hoc network in heterogeneous overlapping networks

A major challenge of the heterogeneous wireless networks is how to jointly utilize the resources of different radio access technologies in an efficient manner. In this paper, system performance, such as the block probability and throughput, was investigated in communication hot spots overlapped by heterogeneous networks: cellular, WLAN, and WiMax networks. Two cooperative load-balancing strategies based on hops-limited routing algorithm of ad hoc network are proposed in order to raise the resource utilization of the whole overlapping heterogeneous networks. They both firstly make a decision whether to admit a new call or not based on common radio resource management strategies, and in overloaded condition, select certain traffic to transfer into targeted BS/AP according to minimum price strategy or minimum load BS/AP and nearest traffic strategy, which take into account these factors such as load index, number of hops, traffic prediction, cost, etc. An analytical model is used to compute the call block probability and throughput performance for two different traffic models. Simulation results show that the proposed load-balancing strategies can distribute traffics to the whole heterogeneous wireless networks, decrease the call block probability, improve system throughputs efficiently, and obviously outperform HM-MACA and HS-TC load-balancing strategies.     

联合时空特征的视频分块压缩感知重构

为了提高视频压缩感知(CS)重构算法的率失真性能,该文提出利用视频的时空特征进行联合重构。为了不引入过多的复杂度,采集端以固定采样率对帧内各块进行测量;重构端则在最小全变差(TV)重构模型的基础上,分别加入利用时空自回归(AR)模型和多假设(MH)模型所形成的正则化项,以提高预测-残差重构的性能。另外,考虑到视频源的统计特性在时空域中是动态变化的,讨论了5种不同的帧间预测模式对重构精度和重构计算复杂度的影响。仿真实验表明,所提出的重构算法能够以一定的计算复杂度为代价有效地改善视频重构质量,且在关键帧采样率高于非关键帧的情形下,帧间预测模式的改善也可一定程度上提高视频重构质量。     

激光角膜矫正术中所用激光波长的选择

用分光光度计测定了12例兔角膜和1例人角膜的吸收光谱,结果表明波长小于300nm的准分子激光和波长在1.88μm～2.64μm,2.36μm～40μm的激光,均可对角膜进行切割并可望用于激光角膜矫正术。     

自由电子激光的小型化研究

本文通过对自由电子激光输出波长的分析,指出了自由电子激光小型化的研究方向─-微型摆动器的研究。在分析了小周期摆动器研究现状的基础上,提出了电流摆动器。它不但具有与静磁摆动器相同的效果,而且它的周期可以任意调节。因而,它便于控制。最后,还指出了有待进一步研究的问题。     

掺Er石英光纤的1560nm光纤激光和超荧光

用Ar离子514.5nm激光泵浦掺Er石英光纤产生了1560nm的激光和超荧光输出。激光最大输出功率5.4mW,斜率效率9.5％;超荧光最大输出功率1.6mW,并观察到光纤超荧光的谱窄化现象。     

大鼠缺血性卒中光化学模型研究

本文基于光化学反应机理，对大鼠缺血性卒中光化学模型进行研究，指出光化学反应诱导ＶＥＣ功能异常，从而加速了血小板聚集，导致血管栓塞。该模型制作简单，相对非侵害，有可能替代大脑动脉闭塞的缺血性卒中模型。     

射频激励CO_2激光器的阻抗匹配及调制的实验研究

论述了射频（ＲＦ）激励气体放电所必须的在ＲＦ源与激光头放电气体之间的阻抗匹配器的工作原理及其实验，并依据研制成功的千瓦级ＲＦ激励快轴流ＣＯ２激光器的实际参数，论证了气体放电阻抗的计算、动态阻抗调配及ＲＦ泵浦调制的激光实验。     

半导体微晶掺杂玻璃的电致二阶非线性光学效应

报道了若干半导体微晶掺杂玻璃的电致二阶非线性光学效应的一些实验结果，并对其形成机理进行了讨论     

Study on the dispersion characteristic of the plasma-loaded relativistic BWO

The dispersion characteristic of the plasma-loaded relativistic backward wave oscillator has been analyzed. The theoretical model has been established and the numerical calculations accord with the experimental results, which provides some useful suggestions on the designing of slow-wave structure of BWO.