Size Effects on the Mechanical Properties of Nanoporous Graphene Networks

It is essential to understand the size scaling effects on the mechanical properties of graphene networks to realize the potential mechanical applications of graphene assemblies. Here, a “highly dense‐yet‐nanoporous graphene monolith (HPGM)” is used as a model material of graphene networks to investigate the dependence of mechanical properties on the intrinsic interplanar interactions and the extrinsic specimen size effects. The interactions between graphene sheets could be enhanced by heat treatment and the plastic HPGM is transformed into a highly elastic network. A strong size effect is revealed by in situ compression of micro‐ and nanopillars inside electron microscopes. Both the modulus and strength are drastically increased as the specimen size reduces to ≈100 nm, because of the reduced weak links in a small volume. Molecular dynamics simulations reveal the deformation mechanism involving slip‐stick sliding, bending, buckling of graphene sheets, collapsing, and densification of graphene cells. In addition, a size‐dependent brittle‐to‐ductile transition of the HPGM nanopillars is discovered and understood by the competition between volumetric deformation energy and critical dilation energy.     

Broadband polarized photodetector based on p-BP/n-ReS2 heterojunction

Two-dimensional(2D) atomic crystals,such as graphene,black phosphorus(BP) and transition metal dichalcogenides(TMDCs) are attractive for use in optoelectronic devices,due to their unique crystal structures and optical absorption properties.In this study,we fabricated BP/ReS2 van der Waals(vdWs) heterojunction devices.The devices realized broadband photoresponse from visible to near infrared(NIR)(400–1800 nm) with stable and repeatable photoswitch characteristics,and the photoresponsivity reached 1.8 mA/W at 1550 nm.In addition,the polarization sensitive detection in the visible to NIR spectrum(532–1750 nm) was demonstrated,and the photodetector showed a highly polarization sensitive photocurrent with an anisotropy ratio as high as 6.44 at 1064 nm.Our study shows that van der Waals heterojunction is an effective way to realize the broadband polarization sensitive photodetection,which is of great significance to the realization and application of multi-functional devices based on 2D vdWs heterostructures.     

水平路径上多帧湍流退化图像重建

为了重建水平路径上远距离成像系统获取的湍流退化图像,提出去除形变和振铃的分块多帧盲反卷积方法.首先按采集的顺序将图像序列分成若干图像组,通过B-spline基函数配准方法去除非等晕块之间的形变,第二步通过基于块的时域融合算法去除等晕块间的振铃,得到衍射受限的湍流退化图像,最后将所得的多帧图像进行频域重建,复原高质量图像.实验表明,所提出的算法适合于水平路径上获取的退化图像的重建,得到较高的主观视觉图像质量.     

高清化现代音乐厅建设

本文介绍徐州音乐厅建设中的四大关键系统:音响系统、灯光系统、舞台机械和反声罩系统、高清转播车系统。系统设计中既要达到音乐剧场声学要求,又要满足高清电视直播要求。并详细介绍了防火幕、LED屏、反声板的一体化组合幕墙创新设计。     

Dopamine‐Modified Cationic Conjugated Polymer as a New Platform for pH Sensing and Autophagy Imaging

A dopamine‐modified conjugated polymer PFPDA is synthesized and characterized. At low pH, dopamine exists in its hydroquinone form and lacks the ability to quench fluorescence. At high pH, the proportion of the quinone form of dopamine increases due to its autooxidation, and efficient intramolecular electron transfer from the polymer main chain to quinone occurs, resulting in the quenching of the fluorescence of PFPDA. Thus, PFPDA exhibits a fluorescence “turn‐on” response at low pH. PFPDA possesses excellent photostability and exhibits no cytotoxicity, which makes it a good fluorescent material for pH sensing and cell imaging. A light‐induced hydroxyl anion emitter, MGCB, is also used to change the pH of the solution and thus regulate the fluorescence of PFPDA via remote control under light irradiation. Because the cytoplasm becomes acidic when cell autophagy occurs, PFPDA can also be used for autophagy imaging of HeLa cells with good selectivity.     

MPEG-2视频编码标准及CLM4400视频编码芯片简介

本文通过MPEG-2和MPEG-1在视频方面的比较，简略地介绍了MPEG-2视频标准，并附带介绍了C-CUBE公司的MPEG-2视频编码芯片CLM4400的功能和应用前景。     

镍基超合金的Nd-YAG激光熔敷涂层行为研究

对ЖС6y、К24、К17三种镍基超合金的几种材料的Nd—YAG激光熔敷涂层行为进行了试验研究,并与三种超合金激光重熔行为进行了对比。研究表明,三种镍基超合金的重熔性都很差,热裂纹敏感性高,重熔区出现很多凝固裂纹。几种粉末涂层行为不尽相同,但对超合金基材的裂纹敏感性都有程度不同的改善,大大减少甚至抑制了基村上裂纹的产生,并在其与基材的界面处形成一白亮的熔合区,达到冶金结合。采用某几种钴基合金和镍基合金粉末,可在某种超合金基材上获得高质量无裂纹涂层。     

PLC提高性实验的实验教学改革探索

介绍PLC即可编程序控制器在实验教学中进行的提高性实验,提高性实验之一是PLC对三台鼠笼异步电动机的自动与手动控制,PLC指令的灵活应用及实现。     

一种高可靠GNSS接收机位同步算法

位同步技术是GNSS接收机技术的重要组成部分,位同步错误会导致接收机伪距解算错误及无法正确解调电文。针对弹载GNSS接收机的高可靠性要求,提出了一种高可靠GNSS接收机位同步算法,对最大似然位同步算法进行了改进。在非相干积分过程中等间隔提取中间结果进行观测,综合多次观测结果和最终非相干积分结果进行位同步判断。数值仿真与分析表明,在弱信号情况下,在不增加估计时间的前提下,可以大幅度减小错误同步概率,对于提高弹载GNSS接收机可靠性有着重要意义。