Increasing the luminous efficiency of an MEH-PPV based PLED using salmon DNA and single walled carbon nanotube

The combined effect of a salmon deoxyribonucleic acid (DNA)-based electron blocking layer and a single walled carbon nanotube (SWCNT) composite-based electron transport layer on the performance of a poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) polymer light emitting diode (PLED) has been examined. The SWCNT network in the composite layer improves electron injection from cathode and the DNA blocks these high mobility electrons at the electron blocking layer-polymer interface, leading to high luminance from the device. The luminous efficiency of the PLED is increased ∼20 times compared to that of a PLED using only MEH-PPV.     

改进Canny算法在钢印数字特征提取中的应用

边缘检测是实现图像分割、特征提取和图像理解的基础.研究了传统Canny算子的优势与不足.在此基础上,提出了一种快速分块自适应Canny算法.方法首先按字符大小分割图像,然后在每一块上进行自适应边缘检测.自适应边缘检测是在平滑图像的同时得到高斯滤波尺度参数,然后采用Otsu方法的自适应阈值计算Canny算子的高、低门限值.实验结果表明,方法不需人工设定参数就能自动提取不同光照背景下的钢印数字边缘,而且能有效抑制噪声,与传统Canny算子相比,边缘连接程度最佳,噪声敏感程度较低,实时性较强.     

Dark current suppression of amorphous selenium based photosensors by the ZnO hole blocking layer

To study the influence of defects in the hole blocking layer (HBL) on the dark current of amorphous selenium (a-Se) based photosensors, we prepared ZnO thin films by reactive sputter deposition (RSD) for the use as the HBL of the photosensors. The ZnO HBL layers prepared with different oxygen flow rates were characterized by X-ray photoelectron spectroscopy, Raman scattering analysis and photoluminescence, indicating that the density of oxygen vacancies in the ZnO thin films is significantly affected by the oxygen flow rate. The deep level transient spectroscopy measurement reveals two hole trap levels present in the RSD deposited ZnO thin films; one is at 0.94 eV and the other at 0.24 eV above the valence band edge. The electrical performance of the a-Se photosensor is largely influenced by the amount of oxygen vacancies in the ZnO thin film. The a-Se photosensor with the ZnO HBL of the most oxygen vacancies has the lowest dark current and demonstrates the highest breakdown field.     

Hole blocking PbI2/CH3NH3PbI3 interface

Modulated charge separation across (MO)/CH₃NH₃PbI₃ and (MO)/PbI₂/CH₃NH₃PbI₃ (MO = TiO₂, MoO₃) interfaces was investigated by surface photovoltage (SPV) spectroscopy. Perovskite layers were deposited by solution‐based one‐step preparation and two‐step preparation methods. An unreacted PbI₂ layer remained at the interface between the metal oxide and CH₃NH₃PbI₃ for two‐step preparation. For the two‐step preparation on TiO₂, the SPV signal related to absorption in CH₃NH₃PbI₃ increased in comparison to the one‐step preparation due to electron transfer from CH₃NH₃PbI₃ via PbI₂ into TiO₂ whereas the SPV signal related to defect transitions decreased. For the one‐step preparation on MoO₃, holes photogenerated in CH₃NH₃PbI₃ recombined with electrons in MoO₃. In contrast, a hole transfer from CH₃NH₃PbI₃ towards MoO₃ was blocked by the PbI₂ interlayer for the two‐step preparation on MoO₃. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

电流阻挡层结构对垂直发光二极管芯片老化特性之研究

发现ICP damage制作电流阻挡层的制程会导致垂直结构LED在老化过程中发生漏电。通过更换反射层的金属及EMMI&SEM分析,发现老化漏电的原因来源于反射金属——Ag的电迁移,迁移通道可能来源于ICP打开穿透位错的封口。在缺陷位错内填入低电迁移率金属并检测。结果表明,填入低电迁移率金属后既解决了老化漏电问题,同时不影响芯片的初始光电特性。     

OBS考虑优先级的突发包碎片可控合并重传算法

为了降低光突发交换网络中突发包的丢失率、降低网络路径的阻塞率、减小突发包冲突的概率,提出了考虑优先级的突发包碎片可控合并重传算法。当网络中数据通信发生冲突时,该算法能根据优先级进行突发包的分片,核心节点将这一信息反馈给边缘节点,边缘节点根据突发碎片的优先级以一定的概率重传被丢弃的突发包分片;同时,针对由于多次重传导致的突发包碎片过多的问题,该算法还按照突发包碎片的优先级顺序进行碎片重组,大大降低了网络的阻塞率。结果表明,相比以往的冲突解决算法,此算法在网络业务繁忙时的数据丢比特率和网络阻塞率方面的改善作用有比较明显的优势。这一结果对光突发交换网络的网络的性能改善方面是有帮助的。     

一种光交换核心节点调度算法研究

光交换核心节点是光交换网络的核心设备,其性能的优劣直接影响网络的吞吐量、时延等重要指标。文章提出一种SWC-MSD(基于波长变换器的多播空分交换)模块的严格无阻塞光交换核心节点,在此基础上提出了三种调度算法,通过数学分析和实验仿真验证了算法的正确性。考察了这种核心节点在有无波长变换以及业务优先级不同的场景下阻塞率的变化情况,结果表明所提出的严格无阻塞光交换核心节点具有较低的阻塞率。     

High UV absorption efficiency of nanocrystalline ZnO synthesized by ultrasound assisted wet chemical method

Ultrasound assisted wet-chemical method has been carried out to incorporate different metal and non-metal ions such as; Li, S and Ag into ZnO. Characteristic studies on the structural and optical properties of the samples especially; the ultra-violet (UV) light absorption have been carried out. X-ray diffraction (XRD) analysis shows the formation of hexagonal crystal structure of ZnO along with changes in crystallinity and micro-strain with impurity doping. The morphology of the doped samples changes from particle like structure to flower and rod like structures showing the influence of dopant ions on nano ZnO growth. Infra-red (IR) transmittance spectra give information about the presence of metal–oxygen bond along with other stretching and bending modes. UV–visible absorption studies show the narrowing and sharpening of UV absorption band along with a blue shift for the doped samples. This shows the intensification in the excitonic absorption in ZnO after doping specific elements which will find application in UV blocking agents. Photoluminescence (PL) measurement shows the presence of excitonic emission and emissions due to intrinsic defects and external impurities in UV and visible regions respectively. These emission bands show a change in their position and intensity which has been explained on the basis of the existence of impurity levels in the band gap of ZnO.     

高压直流线路纵差保护不正确动作分析与改进措施

介绍了高肇、兴安直流输电系统87DCLL的动作原理与闭锁逻辑,统计并分析了近几年87DCLL的保护动作情况,结合两起实例对87DCLL故障初始时刻被闭锁的保护动作过程进行分析,指出＂600 ms闭锁逻辑＂导致87DCLL在线路高阻接地故障时无法正确动作,暴露出87DCLL保护逻辑沿用电力线路载波通信配置的设计缺陷,并对此提出了改进措施。     

Packet reordering analysis for concurrent multipath transfer

Path diversity of different concurrent paths inevitably introduces out‐of‐order packet delivery, which leads to unnecessary retransmissions and a severely lowered data throughput. In order to analyze the fundamental behavior and influencing factors of packet reordering, several sets of simulation‐based multipath experiments are conducted with different aggregating paths. In addition, the relationship between reordering and number of paths are discussed. Furthermore, an end‐to‐end measurement study of packet reordering in concurrent multipath transfer is presented. To simply the analysis process, a cumulative distribution function of transmission delay for each packet is used. The model is proved to be an effective one by contrastive analysis. Finally, some solutions to handle it are provided with a further discussion. Copyright © 2013 John Wiley & Sons, Ltd.