中子探测和照相技术在无损检测中的应用

本文简述了中子照相探测和照相技术的原理，方法和特征，介绍了３００＾＃反应堆中子照相装置的性能，及其在无损检测中的应用和取得的某些结果，并概述了目前中子照相技术在材料科学研究中的应用概况。     

超声无损检测的应用与探讨

超声无损检测是物体无损检测的一种重要方法，几乎应用到所有工业部门。本文回顾了超声无损检测技术的发展历史，阐述了超声无损检测技术应用现状，并展望超声无损检测技术未来发展趋势。     

基于Cloud服务的新媒体互动技术在广播电视系统中的应用

目前以云端形式服务平台的日趋成熟,为新媒体业务提供了完整的视频采样、编码、推流、转码、分发、拉流、解码和播出等解决方案,为直播提供了各种场景的接口服务,极大程度上有效解决了直播中的技术难点及网络细节问题。传统广播电视系统结合新媒体互动技术实现多端、多地实时互动的创新应用,给新媒体和传统媒体带来了新的直播形式和效果,大大提升了直播的多样性和互动性,也必将成为今后互联网化直播的重要技术手段。     

基于有限元理论的飞机蒙皮搭接结构腐蚀红外检测建模分析

飞机蒙皮搭接结构的腐蚀问题直接危害飞机的使用寿命和结构强度,制约飞行安全。由于腐蚀发生位置隐蔽性高,常规无损检测的检测效果不理想。利用有限元分析方法,使用AN-SYS软件模拟检测环境,通过建立飞机蒙皮搭接结构模型,计算模型表面温度场分布。重点从腐蚀面积、腐蚀深度、表面划伤等问题对红外检测技术的可行性进行了分析,为其对蒙皮搭接结构检测的应用提供了理论依据。     

Remote Optical Non-Destructive Inspection Technique for Metal and Composite Structures

This paper presents a laser based non-destructive inspection technique which is purely non-contact. An acoustic device is used to remotely excite the material under inspection while a scanning laser vibrometer is employed to measure the resulting vibrations. The test materials, mostly aluminum or composite aircraft structures, have been successfully inspected from a standoff distance of at least a meter. The NDI system clearly shows the defect locations overlaid on the images of the test objects for ease of the end user. Metal and composite delamination and subsurface corrosion in aluminum structures are among the defects that were detected.     

Aromatic‐Diimide‐Based n‐Type Conjugated Polymers for All‐Polymer Solar Cell Applications

All‐polymer solar cells (all‐PSCs) have attracted immense attention in recent years due to their advantages of tunable absorption spectra and electronic energy levels for both donor and acceptor polymers, as well as their superior thermal and mechanical stability. The exploration of the novel n‐type conjugated polymers (CPs), especially based on aromatic diimide (ADI), plays a vital role in the further improvement of power conversion efficiency (PCE) of all‐PSCs. Here, recent progress in structure modification of ADIs including naphthalene diimide (NDI), perylene diimide (PDI), and corresponding derivatives is reviewed, and the structure–property relationships of ADI‐based CPs are revealed.     

基于隐式增量动态逆的水下运载器出水姿态控制

显式动态逆控制直接利用非线性对消来实现对系统的精确线性化,但由于实际模型存在不确定性因而会造成在对消过程中存在逆误差,使得控制的鲁棒性难以保证。在解决水下运载器出水运动问题中,由于存在较强的不确定性,显式动态逆控制无法消除逆误差的影响。出水过程中水动力变化剧烈同时海浪强烈作用,因此需要对姿态控制问题进行着重研究。在仿射形式的水下运载器出水运动数学模型基础上,推导并得到了隐式增量形式的动态逆控制律,利用层叠结构思想将系统划分为慢快两个回路。在时标分离的慢快回路基础上,引入状态变化率反馈,设计了不依赖精确数学模型的隐式增量控制律,提高了控制的鲁棒性。基于隐式动态逆相应的控制算法,考虑海浪作用、水动力参数摄动以及测量噪声的影响下,对水下运载器出水姿态进行跟踪控制,验证了控制律的有效性和合理性。     

鲁棒镇定受到干扰的非线性微分包含系统

研究带有干扰的非线性微分包含系统的镇定问题. 基于凸锥Lyapunov函数方法, 首先, 对于无干扰的这类系统, 设计可使闭环系统全局镇定的连续反馈控制律. 其次, 通过状态反馈, 对于受到两类有界干扰的这类微分包含系统的可达集进行了估计. 最后, 通过一个仿真例子说明所提出的设计方法的有效性.     

Time-varying control via nominal trajectory linearization for an air-breathing hypersonic vehicle

A time-varying control law via nominal trajectory linearization for an air-breathing hypersonic vehicle (ABHV) model is applied. Feasible guidance command signal serials are generated by nonlinear dynamic inverse (NDI) method considering interactions between aerodynamic effects and propulsion systems. Multiple-time-scale continuous time-varying control, which meets the requirement with accurate, robust, and decoupled tracking of both the commanded trajectory and angular rate profiles in the presence of modeling uncertainties and external disturbances are applied. The simulations for an ABHV model with modeling uncertainties, wind gust, and measuring noises are presented to demonstrate the capacity and reliability of this proposed method.     

Defect tolerance assessment of ARIANE 5 structures on the basis of damage mechanics material modelling

Damage mechanics based material models have been applied to establish fracture control procedures for the failure prediction of ARIANE 5 main structural components as the booster cases including welds, the main stage, and the upper stage cryogenic tank. The main goals of the damage mechanics based investigations were the accurate failure prediction, the clarification of dependency of fracture toughness on geometry, the calibration of analytical methods and the interpretation and optimisation of small scale fracture tests for material characterization and quality assurance.The results of these investigations allowed a failure prediction accuracy with analytical tools which is close to 3D numerical simulations. This could be demonstrated both with ductile (Gurson) and brittle (RKR) damage mechanics models.