蒙皮反射的背景辐射对亚声速飞机红外特征的影响研究(一):方法

基于CFD计算得到的流场、温度场结果和Modtran计算得到了环境辐射数据,建立了典型背景下的飞行器红外辐射特征计算模型。计算中考虑了波段、季节、发射率和双向反射函数等因素。通过地面试验数据,对计算方法进行了验证,计算值与试验数据吻合较好。该模型为更准确地分析飞行器的红外辐射特征,以及更合理地评价红外抑制措施的抑制效果提供了方法和工具。     

DNA/Tannic Acid Hybrid Gel Exhibiting Biodegradability,Extensibility, Tissue Adhesiveness,and Hemostatic Ability

DNA has emerged as a novel material in many areas of materials science due to its programmability. Especially, DNA hydrogels have been studied to incorporate new functions into gels. To date, only a few methods have been developed for fabricating DNA hydrogels, such as the use of complementary sequences or covalent bond. Herein, it is demonstrated that one of the most well‐known plant‐derived polyphenols, tannic acid (TA), can form a DNA hydrogel which is named TNA hydrogel ( T A + D NA ). TA plays a role as a “molecular glue” by a new mode of action reversibly connecting between phosphodiester bonds, which is different from the crosslinking utilizing complementary sequences. TA intrinsically degrades due to ester bonds connecting between pyrogallol groups, causing a degradable DNA hydrogel. Furthermore, TNA gel is multifunctional in that the gel is extensible upon pulling and adhesive to tissues because of the rich polyphenol groups in TA (ten phenols per TA). Unexpectedly, TNA gel exhibits superior in vivo hemostatic ability that can be useful for biomedical applications. This new DNA hydrogel preparation method represents a new technique for fabricating a large amount of DNA‐based hemostatic hydrogel without chemically modifying DNA or requiring the crosslinking by complementary sequences.     

In Situ Preparation of Sandwich MoO3/C Hybrid Nanostructures for High‐Rate and Ultralong‐Life Supercapacitors

This work presents a design of sandwich MoO₃/C hybrid nanostructure via calcination of the dodecylamine‐intercalated layered α‐MoO₃, leading to the in situ production of the interlayered graphene layer. The sample with a high degree of graphitization of graphene layer and more interlayered void region exhibits the most outstanding energy storage performance. The obtained material is capable of delivering a high specific capacitance of 331 F g^?1 at a current density of 1 A g^?1 and retained 71% capacitance at 10 A g^?1. In addition, nearly no discharge capacity decay between 1000 and 10 000 continuous charge–discharge cycles is observed at a high current density of 10 A g^?1, indicating an excellent specific capacitance retention ability. The exceptional rate capability endows the electrode with a high energy density of 41.2 W h kg^?1 and a high power density of 12.0 kW kg^?1 simultaneously. The excellent performance is attributed to the sandwich hybrid nanostructure of MoO₃/C with broad ion diffusion pathway, low charge‐transfer resistance, and robust structure at high current density for long‐time cycling. The present work provides an insight into the fabrication of novel electrode materials with both enhanced rate capability and cyclability for potential use in supercapacitor and other energy storage devices.     

Self‐Powered,Room‐Temperature Electronic Nose Based on Triboelectrification and Heterogeneous Catalytic Reaction

Herein, a self‐powered electronic nose strategy with highly selective gas detection is described. The electronic nose is a two‐dimensional microarray based on the triboelectrification between ZnO nanowires and the dielectric layers, and the heterogeneous catalytic reaction occurring on the nanowires and on the NiO nanoparticles. These electronic noses show the ability to distinguish between four volatile organic compound (VOC) gases (methanol, ethanol, acetone, and toluene) with a detection limit of 0.1% at room temperature using no external power source.     

Direct Transfer Printing with Metal Oxide Layers for Fabricating Flexible Nanowire Devices

A direct printing method for fabricating devices by using metal oxide transfer layers instead of conventional transfer media such as polydimethylsiloxane is presented. Metal oxides are not damaged by organic solvents; therefore, electrodes with gaps less than 2 μm can be defined on a metal oxide transfer layer through photolithography. In order to determine a suitable metal oxide for use as transfer layer, the surface energies of various metal oxides are measured, and Au layers deposited on these oxides are transferred onto polyvinylphenol (PVP). To verify the feasibility of our approach, Au source–drain electrodes on transfer layers and Si nanowires (NWs) addressed by the dielectrophoretic (DEP) alignment process are transferred onto rigid and flexible PVP‐coated substrates. Based on transfer test and DEP process, Al₂O₃ is determined to be the best transfer layer. Finally, Si NWs field effect transistors (FETs) are fabricated on a rigid Si substrate and a flexible polyimide film. As the channel length decreases from 3.442 to 1.767 μm, the mobility of FET on the Si substrate increases from 127.61 ± 37.64 to 181.60 ± 23.73 cm² V^?1 s^?1. Furthermore, the flexible Si NWs FETs fabricated through this process show enhanced electrical properties with an increasing number of bending cycles.     

主三镜一体化离轴三反光学系统设计

离轴三反光学系统具有成像质量高、可实现大视场、无遮拦等优点,但其装调难度大,镜面支撑结构质量大。为解决这些问题,基于三级像差理论,研究一种主镜、三镜可集成一体化的大视场离轴三反光学系统,并以焦距为1 200 mm,F数为12,视场为101的光学系统为例进行了验证设计。结果表明:调制传递函数接近衍射极限,视场内平均波像差RMS值为/55,最大波像差RMS值为/22。设计结果显示,光学系统装调自由度由12个减少到6个,可使光机系统可得到简化,实现了主三镜一体化设计。     

基于数据增强的小样本通信干扰识别技术

干扰识别是通信抗干扰过程的前置环节,为抗干扰决策和波形选择提供关键的先验知识,是抗干扰成功与否的关键步骤.在复杂的电磁条件下,对干扰信号进行大量标记往往是困难的,并且对干扰识别的实时性要求很高.针对上述问题,研究了一种基于数据增强的小样本干扰信号识别技术,以解决小样本条件下分类器训练过程的欠拟合问题.小样本条件下,在正...     

原子层沉积低温生长α-MoO3薄膜

以六羰基钼和氧气为前驱体,通过等离子增强原子层沉积技术（PE-ALD）在硅基片上实现了α-MoO₃薄膜的低温制备。利用X射线衍射仪、扫描电子显微镜、原子力显微镜、X射线光电子能谱仪等手段对薄膜的晶体结构、表面形貌及薄膜成分进行表征和分析。研究发现衬底温度和氧源脉冲时间对MoO₃薄膜的晶体结构和表面形貌变化起关键作用。当衬底温度为170℃及以上时所制备的薄膜为α-MoO₃;适当延长ALD单循环中的氧源脉冲时间有利于低温沉积沿（0k0）高度择优取向的MoO₃薄膜。根据对不同厚度MoO₃薄膜表面的原子力显微图片分析,MoO₃薄膜为岛状生长模式。