Amphibious sensor of temperature and refractive index based on D-shaped photonic crystal fibre filled with liquid crystal

ABSTRACT

A D-shaped photonic crystal fibre filled with liquid crystal was demonstrated as an amphibious sensor for detection of both temperature and refractive index, when combined with plasma materials. Specifically, the optical component is implanted into a complete optical system ensuring modulation of the external electric field. When the refractive index of the external solution changes from 1.0 to 1.6, the y-polarised mode has a loss spectrum with a wavelength sensitivity of up to 2275 nm/RIU, and the corresponding amplitude sensitivity is ?88.2RIU^?1. When the perceived temperature changes from 15°C to 50°C, the temperature of the sensor is correspondingly expressed as the maximum wavelength sensitivity of 9.09 nm/°C and the amplitude sensitivity of ?0.311°C^?1. In addition, the actual micro-operation processes have been studied in detail, such as polishing depth, coating thickness and coating method. This provides practical ideas for real-time sensing analysis that requires harsh environments.     

Nitro-, Cyano-, and Methylfuroxans,and Their Bis-Derivatives: From Green Primary to Melt-Cast Explosives

In the present work, we studied in detail the thermochemistry, thermal stability, mechanical sensitivity, and detonation performance for 20 nitro-, cyano-, and methyl derivatives of 1,2,5-oxadiazole-2-oxide (furoxan), along with their bis-derivatives. For all species studied, we also determined the reliable values of the gas-phase formation enthalpies using highly accurate multilevel procedures W2-F12 and/or W1-F12 in conjunction with the atomization energy approach and isodesmic reactions with the domain-based local pair natural orbital (DLPNO) modifications of the coupled-cluster techniques. Apart from this, we proposed reliable benchmark values of the formation enthalpies of furoxan and a number of its (azo)bis-derivatives. Additionally, we reported the previously unknown crystal structure of 3-cyano-4-nitrofuroxan. Among the monocyclic compounds, 3-nitro-4-cyclopropyl and dicyano derivatives of furoxan outperformed trinitrotoluene, a benchmark melt-cast explosive, exhibited decent thermal stability (decomposition temperature >200 °C) and insensitivity to mechanical stimuli while having notable volatility and low melting points. In turn, 4,4′-azobis-dicarbamoyl furoxan is proposed as a substitute of pentaerythritol tetranitrate, a benchmark brisant high explosive. Finally, the application prospects of 3,3′-azobis-dinitro furoxan, one of the most powerful energetic materials synthesized up to date, are limited due to the tremendously high mechanical sensitivity of this compound. Overall, the investigated derivatives of furoxan comprise multipurpose green energetic materials, including primary, secondary, melt-cast, low-sensitive explosives, and an energetic liquid.     

基于变密度法的平模台振加强筋布局优化

针对混凝土预制构件水平成型振动台(简称平模台振)振动效果改进的问题,提出了通过优化振动台面加强筋布局来提高其振动效果的方法.基于变密度拓扑优化法,建立以加强筋单元相对密度为设计变量,振动台面柔度最小为目标的优化模型,并进行灵敏度分析,采用最优准则法求解优化模型;根据拓扑优化结果,对振动台面加强筋进行布局优化,获得了合理...     

稀土X (X=La、Ce、Pr、Nd)修饰单层h-MoS2的NO气敏性

为提高h-MoS₂对NO的气敏性,采用第一性原理研究了X(X=La、Ce、Pr和Nd)对h-MoS₂的稳定性、吸附特性、功函数和伏安特性的影响.研究结果表明：X(X=La、Ce、Pr和Nd)取代Mo原子后得到的形成能均为负,说明掺杂体系容易形成且稳定存在.同时X掺杂后的h-MoS₂布居数相比于未掺杂前的大,也说明掺杂有利于体系稳定.NO吸附在La、Ce原子顶部位置的吸附能为-1.215 eV、-1.225 eV,吸附距离分别为2.475?、2.854?,具有明显的化学吸附特征.同时Hirshfeld转移电荷分别为0.213e和0.325e,具有明显的受体特征,提高了气敏性.La和Ce掺杂后能明显改变功函数的大小,也说明La和Ce能提高h-MoS₂对NO的气敏性.施加电场后能有效提高Pr掺杂体系的吸附强度,增大Hirshfeld转移电荷,对功函数的改变最大,所以电场对Pr掺杂体系的影响非常明显.通过分析掺杂体系的伏安特性曲线,La、Ce两掺杂体系的电流分别由0增大到5.3μA和4.8μA,而Pr、Nd...     

透平叶栅三维粘性气动反问题的控制理论方法

将基于控制理论的形状优化设计方法应用于粘性可压流动条件下的透平叶栅三维气动反设计,详细推导了三维N-S方程伴随系统的偏微分方程组及其各类边界条件.讨论了伴随系统的解的适定性条件,并由此给出应用N-S方程进行气动优化的目标函数的选取限制.研究了伴随方程的数值求解技术,给出敏感性导数的最终计算式,结合拟牛顿算法发展了三维透平叶栅粘性反问题的气动设计方法.     

光敏热成像材料的化学增感进展

本文综述了近年来光敏热成像(PTG)材料在化学增感方面取得的相关新进展.在分析文献结果以及结合作者相关实验数据的基础上提出了进行化学增感的有效方法,即提高卤化银外部潜影的形成效率,或者提高银离子供应源在显影过程中的热迁移能力.文章对PTG材料在化学增感方面的发展提出了一些见解和想法.     

楔条形阳极探测器位置灵敏的理论计算

通过对楔条形阳极探测器位置灵敏坐标计算公式的推导,证明了楔形和条纹分布面积所对应的级数是等差级数.分析了楔形底宽和条纹宽度等差系数这两个设计参量对探测灵敏度的影响.研究了电极电容的电容性耦合效应对位置灵敏的影响,通过对楔条形阳极探测器坐标计算公式的修正,可在不影响分辨率的前提下有效地消除电容性耦合效应所产生的扭曲变形.     

论红外探测系统的噪声等效温差

介绍了基于噪声等效温差(Noise Equivalent Temperature Difference,NETD)定义的NETD公式推导过程,讨论了相关系统参数对NETD的影响。然后分析了环境温度变化对NETD的影响,并给出了相同辐射功率差所对应的等效温差的MATLAB计算方法。     

区块链的安全风险评估模型

随着区块链技术在社会经济领域的应用不断扩大,区块链的安全问题受到越来越多的关注.本文提出了一种新的区块链安全风险评估方法,分别从技术架构和算力两方面量化区块链的安全风险.我们首先根据区块链技术体系架构建立了区块链可信计算基(Blockchain Trusted Computing Base,BTCB),进而设计了一种结...     

一种基于视觉注意模型的可移动目标检测方法

提出了一种基于视觉显著性的目标检测算法,用于对位于地面上的车辆、飞 机等地面可移动目标进行检测和定位。针对地面可移动目标在场景中较小的特点,设计了一种用于对 目标检测进行引导的基于视觉注意机制的目标显著模型。首先,提取图像目标的颜色特征、强 度特征和方向Gabor特征,并将其结合起来用于计算显著图。然后以超像素为单位对 显著值进行计算,并结合人眼视觉敏感度对不同距离的超像素之间的差异进行加权处理。实 验结果表明,本文算法可以有效地检测并定位出复杂背景中的地面可移动目标。