太赫兹技术用于关节软骨检测的研究进展

骨关节炎是主要由软骨组织损伤与退化引起的常见关节疾病,是影响人类健康的重大疾病之一,对于关节软骨组织早期病变的检测可以大大提高疾病的治愈率,然而相关的临床诊断技术尚未发现。近年来,太赫兹技术在医学领域日益受到关注。与传统方法相比,太赫兹辐射能量低,不会产生电离辐射,可高灵敏、无损伤地对生物组织进行成像检测,因此在关节软骨诊断方面具有较大的应用潜力。本文简要介绍了关节软骨的生理与病理情况以及目前关节软骨检测的主要方法,重点总结了太赫兹技术应用于关节软骨检测方面的相关研究工作,分别包括对动物与人类关节软骨的检测,探讨了太赫兹技术在关节软骨检测中所面临的挑战与未来研究展望。     

基于光谱诊断的烃类火焰碳烟形成机理研究综述

碳烟主要是烃类燃料不完全燃烧生成的产物,其对人类健康、空气质量以及燃烧装置的使用寿命都会产生有害影响。碳烟生成是一个复杂的物理化学过程,控制碳烟排放,需要克服碳烟生成和燃烧过程中物理和化学演化的巨大差异,这些差异表现为对碳烟纳观结构和表面官能团随碳烟氧化活性反应变化的深入探索研究。近些年,研究人员对碳烟的生成机理开展了系列研究,对碳烟生成各个物理化学反应阶段有了一定认识。结合光谱诊断技术可深入了解燃烧系统碳烟形成过程,确定碳烟颗粒分子组成、精细结构、浓度分布等特征,也可从碳烟结构变化、黑体辐射强度等方面详细了解碳烟形成过程。该文旨在阐述光谱诊断技术对烃类火焰碳烟表征的研究进展和发展趋势,探讨LIBS, LII和LIF等作为诊断工具在包含背景辐射的火焰中检测碳烟生成过程产生辐射强度准确性等问题。主要介绍了烃类火焰碳烟的形成机理(从前驱体产生、生长到颗粒生成、凝聚,最后进行颗粒氧化)。总结了探测碳烟性质光谱诊断方法的应用以及光谱诊断技术对燃烧过程中碳烟表征的研究现状,包括对碳烟体积分数、温度和基于图像处理的碳烟结构表征,反应碳烟前驱体(多环芳烃)、反应气氛、温度等对碳烟颗粒物生成的影响。最...     

广角任意反射面速度干涉仪的光学性质研究

研究了广角任意反射面速度干涉仪(VISAR)的光学性质。阐述了广角VISAR的原理,指出广角诊断靶中椭球镜的作用是将靶丸内表面成虚像在靶丸中心附近。使用Zemax模拟了成像弯曲对动态干涉条纹形成的影响,提出使用异形光纤面板进行像面矫正。研究了工程误差对干涉仪成像的影响,若要取得良好的成像效果,椭球镜的位置偏差不得多于30 μm,倾角不得超过4°,长轴方向加工误差需小于0.1 μm,短轴方向误差需小于4 μm,镜面反射率应高于70%。讨论了广角VISAR光学研究的进一步发展方向如影响动态条纹的更多可能因素、像面矫正的其他方法、物与像面的光学对应等。     

一种强电磁脉冲辐射场均匀性校准测试装置

目前,辐射场均匀性主要采用单点多次测试的方式来实现,该方式将不可避免地引入因辐照信号自身时变特性带来的测量误差;此外,单点多次测试极大地增加了测试时间、测试效率低下。为解决这些问题,本文设计了一种可实现一次多点测试、测试区域可自动调节的装置,仿真表明：该装置可满足500 mm×500 mm~1500 mm×1500 mm区域辐射场9点均匀性测试;在此基础上,在1000 mm×1000 mm测试区域,针对1.35 GHz和2.88 GHz两个频点开展了实验验证,实验表明：设计的测试装置可满足辐射场均匀性9点自动测试要求,大幅提高了测试效率和自动化程度。     

不同微场分布函数对Stark加宽和频移的影响

分别采用Holtsmark,Neutral Point,Nearest-Neighbor和Mayer模型微场分布函数对Stark线型进行了研究,进而得到相应微场函数下的Stark加宽和频移,研究了4种不同的微场分布函数对Stark加宽和频移的影响。研究结果表明,在电子加宽参数不变时,4种微场分布函数对Stark加宽和频移的影响随离子加宽参数的增加而增加;在离子加宽参数不变时,4种微场分布函数对Stark加宽和频移的影响随电子加宽参数的增加而增加;特别是,当离子加宽参数较大时,Mayer模型微场分布函数对Stark加宽和频移的影响异常明显。这说明,微场分布函数对谱线的加宽和频移的影响在离子与离子碰撞剧烈的等离子体环境中尤其显著, 在这样的等离子体环境中,进行等离子体诊断时,选择合适的微场分布函数非常重要。结果对等离子体诊断有一定参考价值。     

Investigation of lubricant induced pre-ignition and knocking combustion in an optical spark ignition engine

An experimental study was performed to investigate lubricant oil induced pre-ignition and knocking combustion process in a single cylinder spark ignition (SI) engine with full bore overhead optical access. Lubricant oil was deliberately injected to the exhaust area through a specially modified direct injector to trigger the stochastic pre-ignition in a premixed air and fuel mixture. Simultaneous heat release analysis and high speed combustion imaging were used to study the pre-ignition and combustion processes. Outlier detection based on robust statistical methods was validated as an effective and efficient approach to identify sporadic pre-ignition. When pre-ignition occurred, the pre-ignited flame-front exhibited much faster propagating speed than that of the normal spark-ignited flame-front in the first stage of flame development. In several cycles, pre-ignition was followed by the pre-ignited propagating flame-front and then a separate spark-ignited flame-front before they subsequently merged together. In a few other cycles, pre-ignition led to heavy knocking combustion caused either by the auto-ignition close to the flame-front or near the cylinder wall, or both. The ultimate knock intensity of such cycles was determined by the timing, size, and location of end-gas auto-ignition of the unburned gas. Furthermore, optical detection of the oil droplet entrained combustion in the cycle subsequent to the knocking combustion cycle implied that high frequency oscillation pressure waves ejected lubricant from the piston-ring crevice.     

A new approach for noninvasive skin blood imaging in microcirculation

A new noninvasive method is proposed for optically imaging blood under skin. A mini-mirror is used to guide the light incident onto the skin surface, while blocking specularly reflected light from the tissue. Moreover, by using two linear polarizers at right angles, the specular reflection can be reduced further, while also blocking the rough surface scattered light. A circular polarizer may be used to obtain the same effect. As a result, the blood flow beneath the surface of skin can be visualized clearly. The effect of the mini-mirror is also analyzed theoretically and experimentally.     

基于586-Driver的无人机飞控计算机智能检测系统研制

传统飞控计算机检测方法以人工操作为主,存在一定的主观性且效率低下的缺点。采用信号门限检测技术,设计了飞控计算机一键式全功能检测方案。以586-Driver板卡为核心,设计了智能检测系统,实现了在全程无人干预情况下对飞控计算机按预设时序逻辑的自动检测。通过系统测试表明：满足某型飞控计算机的检测需求,提高了飞控计算机检测效率,具有实际工程应用价值。     

Laser absorption spectroscopy for combustion diagnosis in reactive flows: A review

Laser absorption spectroscopy (LAS) has been rapidly developed and widely applied to combustion diagnosis in recent decades. As a cost-effective tool for measuring multiple combustion parameters, LAS provides unique properties in terms of accuracy and sensitivity for understanding the reactions and kinetics in reactive flows. Line-of-sight and tomographic LAS techniques have stimulated numerous applications and been proved to be robust for in situ combustion diagnosis in uniform and non-uniform combustion fields, respectively. This review highlights the breakthroughs in the evolution of LAS techniques from the viewpoints of key principles, sensors and instrumentations developed for combustion diagnosis, with particular emphasis on a series of spatially-resolved LAS techniques with their recent applications on obtaining high-fidelity measurement results with minimal intrusion to the practical combustors. Along the way, we note some challenges and requirements for further development of the LAS-based combustion diagnosis.