基于平均值法的LED背光源动态调光二次修正算法

为降低LED背光源的功耗,提高LCD的图像显示质量,提出了一种LED背光源动态调光二次修正算法。采用平均值法得到分区的初始背光灰度值;为了解决灰度截断问题,根据分区灰度最大值与平均值的差值进行第一次修正;为了抑制调光带来的光晕效应,采用空间滤波法进行第二次修正。采用侧入式LED背光源的116.8cm(46in)LCD实验结果表明,采用该算法后,LED背光源平均功耗降低至73.02%,灰度截断率为0.49%,平均PSNR值为67.21dB;典型图像对比度最大达到28 600∶1,显示图像的光晕效应有了明显的改善。二次修正算法能够有效降低背光功耗,增强图像显示质量。     

面向高光谱探测的伪装效果评价方法

20世纪80年代发展起来的高光谱成像技术能充分探测并利用地物的光谱信息,有着较强的伪装识别能力,而传统的伪装评价方法主要基于伪装和背景的空间特征,不适用于基于光谱特征的高光谱伪装探测技术。提出了一种面向高光谱探测的伪装效果评价方法。该方法以伪装目标和背景的光谱特征及光谱导数特征的综合相似度为评价指标,综合相似度值越大则说明伪装效果越好。同时通过实验评价了三种伪装材料的伪装效果,其中绿色棉质布料与背景综合相似度为0.976 6,伪装效果最佳。最后在高光谱图像分类技术基础上提出了错分率的概念,验证了评价方法的客观性。所提出的伪装评价方法对于面向高光谱探测的新型伪装材料的设计有一定的指导意义。     

Photo‐Stable Organic Thin‐Film Transistor Utilizing a New Indolocarbazole Derivative for Image Pixel and Logic Applications

Small molecule pentacene layer has been a representative among many organic thin‐film transistor (OTFT) channels with decent p‐type mobilities, but it is certainly light‐sensitive due to its relatively small highest occupied molecular orbital‐lowest unoccupied molecular orbital (HOMO‐LUMO) gap (1.85 eV). Although a few other small molecule‐based layers have been reported later, their photo‐stabilities or related device applications have hardly been addressed. Here, a new photostable organic layer is reported, heptazole (C₂₆H₁₆N₂), which has almost the same HOMO level as that of pentacene but with a higher HOMO‐LUMO gap (≈2.95 eV). This heptazole OTFT displays a decent mobility comparable to that of conventional amorphous Si TFTs, showing good photostability unlike pentacene OTFTs. An image pixel driving the photostable heptazole OTFT connected to a pentacene/Al Schottky photodiode is demonstrated. This heptazole OTFT also conveniently forms a logic inverter coupled with a pentacene OTFT, sharing Au for source/drain.     

Systematic Doping Control of CVD Graphene Transistors with Functionalized Aromatic Self‐Assembled Monolayers

Recent reports have shown that self‐assembled monolayers (SAMs) can induce doping effects in graphene transistors. However, a lack of understanding persists surrounding the quantitative relationship between SAM molecular design and its effects on graphene. In order to facilitate the fabrication of next‐generation graphene‐based devices it is important to reliably and predictably control the properties of graphene without negatively impacting its intrinsic high performance. In this study, SAMs with varying dipole magnitudes/directions are utilized and these values are directly correlated to changes in performance seen in graphene transistors. It is found that, by knowing the z‐component of the SAM dipole, one can reliably predict the shift in graphene charge neutrality point after taking into account the influence of the metal electrodes (which also play a role in doping graphene). This relationship is verified through density functional theory and comprehensive device studies utilizing atomic force microscopy, X‐ray photoelectron spectroscopy, Raman spectroscopy, and electrical characterization of graphene transistors. It is shown that properties of graphene transistors can be predictably controlled with SAMs when considering the total doping environment. Additionally, it is found that methylthio‐terminated SAMs strongly interact with graphene allowing for a cleaner graphene transfer and enhanced charge mobility.     

Mechanism of Crystallization and Implications for Charge Transport in Poly(3‐ethylhexylthiophene) Thin Films

In this work, crystallization kinetics and aggregate growth of poly(3‐ethylhexylthiophene) (P3EHT) thin films are studied as a function of film thickness. X‐ray diffraction and optical absorption show that individual aggregates and crystallites grow anisotropically and mostly along only two packing directions: the alkyl stacking and the polymer chain backbone direction. Further, it is also determined that crystallization kinetics is limited by the reorganization of polymer chains and depends strongly on the film thickness and average molecular weight. Time‐dependent, field‐effect hole mobilities in thin films reveal a percolation threshold for both low and high molecular weight P3EHT. Structural analysis reveals that charge percolation requires bridged aggregates separated by a distance of ≈2–3 nm, which is on the order of the polymer persistence length. These results thus highlight the importance of tie molecules and inter‐aggregate distance in supporting charge percolation in semiconducting polymer thin films. The study as a whole also demonstrates that P3EHT is an ideal model system for polythiophenes and should prove to be useful for future investigations into crystallization kinetics.     

基于模糊Petri网的舰艇对空作战训练效果评估

针对当前水面舰艇对空作战训练中,缺乏系统、有效的训练效果评估理论问题,探讨了训练效果评估指标体系的构建方法;依据层次分析思想,建立舰艇对空作战训练系统效果评估指标体系;将粗糙集理论与模糊逻辑技术相结合,建立推理规则;将训练系统中各事件转化为模糊Petri网(FPN)的各要素,构建FPN评估模型;应用带权模糊Petri网的矩阵推理算法,借助Matlab工具对仿真实例进行分析计算,并对指标进行评价。     

CMOS图像传感器辐照损伤效应仿真模拟研究进展

CMOS图像传感器(CIS)工作在空间辐射或核辐射环境中遭受的辐照损伤问题备受关注。对CIS辐照损伤效应进行仿真模拟研究有助于深入揭示辐照损伤机理,进而开展抗辐射加固设计,有效提升CIS抗辐照能力。文章通过梳理国内外开展CIS辐照损伤效应仿真模拟研究方面的进展情况,结合课题组已开展的电子元器件辐照效应仿真模拟和实验研究基础,从CIS器件建模、时序驱动电路建模、辐照损伤效应建模、仿真模拟结果校验等方面探讨了CIS辐照损伤效应的仿真模拟方法,分析总结了当前CIS辐照效应仿真模拟研究中亟待解决的关键技术问题。     

磷化镓声光偏转器

该文介绍了一种利用磷化镓(GaP)晶体制作的宽带声光偏转器。该器件采用准超声跟踪结构设计,大幅提高了换能器工作的总长度,实现了带宽与衍射效率的合理兼顾。制作出声光偏转器样品3dB带宽达900MHz,峰值衍射效率达8%@1W,衍射光在声光介质外的动态扫描角为5.2°。在试验过程中发现了异常现象,在1级衍射光斑与2级衍射之间出现了多余的衍射光斑("假点"),形成的机理还有待研究。     

Optical and electrical properties and phonon drag effect in low temperature TEP measurements of AgSbSe2 thin films

Polycrystalline thin films of silver antimony selenide have been deposited using a reactive evaporation technique onto an ultrasonically cleaned glass substrate at a vacuum of 10-5 torr. The preparative parameters, like substrate temperature and incident fluxes, have been properly controlled in order to get stoichiometric, good quality and reproducible thin film samples. The samples are characterized by XRD, SEM, AFM and a UV-vis-NIR spectrophotometer. The prepared sample is found to be polycrystalline in nature. From the XRD pattern, the average particle size and lattice constant are calculated. The dislocation density, strain and number of crystallites per unit area are evaluated using the average particle size. The dependence of the electrical conductivity on the temperature has also been studied and the prepared AgSbSe2 samples are semiconducting in nature. The AgSbSe2 thin films exhibited an indirect allowed optical transition with a band gap of 0.64 eV. The compound exhibits promising thermoelectric properties, a large Seebeck coefficient of 30 mV/K at 48 K due to strong phonon electron interaction. It shows a strong temperature dependence on thermoelectric properties, including the inversion of a dominant carrier type from p to n over a low temperature range 9-300 K, which is explained on the basis of a phonon drag effect.     

Rashba效应下三角量子阱中弱耦合束缚极化子的性质

利用线性组合算符和幺正变换相结合的方法,推导出三角量子阱中弱耦合束缚极化子的基态能量。并讨论了耦合常数,库仑束缚势和电子面密度对极化子基态能量的影响。通过对GaAs材料的数值计算,最后结果显示：由于电-声子耦合作用和Rashba效应的存在,弱耦合束缚极化子的基态能量由四部分组成,而且弱耦合束缚极化子的基态能量随耦合常数,库仑束缚势和电子面密度都发生了分裂。