Output mode characteristics of an in-phase locked gain waveguide array CO2 laser

In this paper,experimental and theoretical studies of the output mode characteristics of an in-phase locked gain waveguide array CO 2 laser are reported.The experimental results of the optical oscillation mode frequency,the far-field intensity distribution and the burnt pattern of the sliced waveguide array laser are obtained.A revised mode expression of the rectangle waveguide,which is suited for this waveguide array CO 2 laser,is proposed.The theoretical simulation results based on the revised mode expression are shown to be in good agreement with the experimental results.     

狭缝光栅、柱面透镜光栅及其新构型在三维显示中的应用

介绍了三维显示技术的研究现状,综述了狭缝光栅和柱面透镜光栅在自由立体显示技术中的重要应用。回顾了各种光栅式自由立体显示系统的结构和原理;提出了如何根据狭缝光栅和柱面透镜光栅的特殊光学性质,在传统的立体显示系统中添加各种光栅形成灵活组合结构来提高立体显示效果,强调了它们在减小串扰、增大视场角、避免摩尔条纹以及提供更全面的三维信息等方面的作用。最后指出基于两种光栅的叠加构成面积大、参数均匀、价格低廉的新型透镜可实现全视差立体显示,对探索自由立体显示技术的研究很有意义。     

一种应用于CMOS图像传感器的电容阵列PGA研究

研究了一种应用于1 024×1 024CMOS图像传感器中的温度计码电容阵列型可编程增益放大器（PGA）。该PGA采用开关电容阵列结构,通过改变输入与反馈电容值,实现了0～18dB的增益;同时,该PGA具有结构简单、电容阵列面积小、带宽大和反馈系数大等特点,其增益带宽50MHz、总谐波失真（THD）小于50dB。该PGA的信号处理能力完全满足12MHz速率、69dB动态范围CMOS图像传感器内部集成ADC对模拟输入信号的要求。     

多组份硅橡胶基末端膨大二级结构粘附性能研究

本文在前期工作基础上,在仿生刚毛一级结构末端固化1层粘附层,制备出末端膨大二级结构,用UMT测试其粘附性能。结果表明：正向滑移单根阵列支杆产生的切向力为5.3 mN,5倍于一级结构的刚毛;末端膨大结构的粘附层因材料组份的不同,其粘附阵列产生的切向粘附力明显不同;倾斜的末端膨大二级结构具有各向异性的粘附特性,正向滑移产生的切向力是逆向滑移的切向力的3.5倍。     

Characterisation of tram noise emission and contribution of the noise sources

The recent expansion of French tram networks and the related local residential complaints mean that a better knowledge of the situations leading to negative reactions from the local inhabitants is required. Hence a research project has been conducted to evaluate and describe noise and vibration emission of trams as well as the perception by the local residents. This paper investigates tram noise emission on common straight track sections, involving two vehicle scales. First the acoustic power and the mean vertical directivity of the total tramset is assessed using an arc of microphones. Then the localisation and the analysis of the main noise sources are performed by means of a cross array during the tram pass-by. Two tram types representing two generations of French rolling stock, both running on two sites with distinct track characteristics, have been investigated considering the effect of speed, tram type, and track type on the noise source contributions and spectral features. Most sources are located in the lower part of the trams, mainly related to rolling noise, with a strong dependence on speed and track type. The tram type dependency, although globally of second importance, influences greatly the noise spectral distribution and behaviour. The HVAC was the only roof-mounted source which could be detected; its contribution towards building storeys becomes significant in configurations of low rolling noise. A tram noise emission model based on the various noise sources has been developed.     

Generalized covering designs and clique coverings

Inspired by the “generalized t‐designs” defined by Cameron [P. J. Cameron, Discrete Math 309 (2009), 4835–4842], we define a new class of combinatorial designs which simultaneously provide a generalization of both covering designs and covering arrays. We then obtain a number of bounds on the minimum sizes of these designs, and describe some methods of constructing them, which in some cases we prove are optimal. Many of our results are obtained from an interpretation of these designs in terms of clique coverings of graphs. © 2011 Wiley Periodicals, Inc. J Combin Designs 19:378‐406, 2011     

Non-uniformity correction algorithm for IRFPA based on motion controllable micro-scanning and perimeter diaphragm strips

Non-uniformity correction is the key issue for the image quality improvement of infrared focal panel array (IRFPA) imaging. A non-uniformity correction (NUC) algorithm for IRFPA based on motion controllable micro-scanning platform and perimeter diaphragm strips is presented. We initially execute one-point calibration to the perimeter detectors, then based on controllable motion of adjacent frames, a special algebraic algorithm is proposed to transport the calibration of the perimeter detectors to those interior un-corrected ones. In this way, the bias parameter of the whole field of view (FOV) is calculated. The algorithm can be easily combined with sub-pixel imaging, thereby improving the quality of thermal imaging system (image spatial resolution and uniformity). All calculations are algebraic, with a low computation load. The algorithm can realize adaptive one point calibration without covering the central FOV rapidly. Experiments on simulated infrared data demonstrate that this algorithm requires only dozens of frames to obtain high quality corrections.     

Improved surface-enhanced Raman scattering of patterned gold nanoparticles deposited on silicon nanoporous pillar arrays

Large-area silicon nanoporous pillar arrays (Si-NPA) uniformly coated with gold nanoparticles was synthesized, and surface-enhanced Raman scattering of rhodamine 6G adsorbed on these gold nanoparticles were studied and compared. It's found that Au/Si-NPA substrate has a significantly high Raman signal sensitivity and good homogeneity. These are attributed to gold nanoparticles with narrow particle-size distribution uniformly coated on the surface and to the enlarged specific surface area for adsorption of target molecules brought by the porous silicon pillars.     

界面条件下线型超声相控阵声场特性研究

开展了界面条件下线型超声相控阵声场特性的研究.将带有楔块的超声相控阵问题合理简化为液固界面的情况进行讨论.根据射线声学理论,计算了单阵元在液固界面存在时的辐射声场,进而推导了聚焦法则,得到了超声线型阵在液固界面存在时的声场、位移场表达式.对安装在楔块上的相控阵换能器的辐射声场进行了仿真,并讨论了聚焦对换能器轴向和横向声场的影响,结果表明利用聚焦能提高分辨率和灵敏度,但聚焦区域之外声束性能更差,在实际检测中要合理利用聚焦. 关键词： 超声相控阵 界面 声场 聚焦     

基于无基底焦平面阵列红外热像仪的理论模型分析

基于双材料微悬臂梁热变形原理的光学读出非制冷红外探测阵列经历了从有基底结构向无基底结构的发展过渡,无基底阵列的红外成像结果和有限元模型分析均表明无基底阵列不满足恒温基底条件.本文结合电学比拟的方法,提出了一种新的基于无基底焦平面阵列(focal plane Array,FPA)的热传递分析的理论模型.分析采用整体考虑的思路,避开了无基底FPA阵列各单元热传递互相影响所产生的复杂热分布分析,并考虑了框架对热量的吸收与传递.理论模型采用外边框与环境等温的边界条件,虽不及有限元方法对边界条件的处理灵活,但也已取 关键词： 光学读出 无基底 非制冷红外成像 焦平面阵列