抛物柱面镜扫描系统设计

本系统用于大尺寸物体(如冷轧钢板)表面缺陷的在线检测。表面检测质量的主要因素是光学系统的设计方案。选用抛物柱面镜装置的特点是检测线上所有的点构成匀速恒定的检测状态。而对大尺寸物体表面缺陷的在线检测,F·θ型式扫描系统是不能满足扫描要求的。     

低旁瓣反射面天线设计

反射面天线设计在追求高增益的同时,往往也要求天线具有较低的旁瓣水平,以防止对其他系统产生干扰。通过分析不同天线形式反射面天线旁瓣的影响因素,研究了低旁瓣反射面天线设计时参数选取原则和方法,总结了低旁瓣反射面天线的设计方法。给出了一个实际工程应用的超低旁瓣双偏置反射面天线的设计实例和性能仿真计算,天线仿真的口径效率优于59%,旁瓣优于-40dB,验证了分析与设计方法的正确性,该方法可用于指导低旁瓣反射面天线的工程设计。     

Influence of helix twisted tape on heat transfer and friction factor in forced circulation V-trough solar water heater

The effect of helix twisted tape with several twist ratios (Y?=?3, 4, 5 and 6) in a V-trough solar water heater for enhancing heat transfer, thermal performance and the friction factor has been examined experimentally in forced circulation with the Reynolds number ranging from 3000 to 23,000. The experimental results of plain V-trough solar collector (PVT) fitted with the standard equations and the variation in the Nusselt number are ±7.23% and the variation in friction factor is about ±5.91%. The PVT has been compared with plain flat plate (PFP) collector. The obtained result shows that the average Nusselt number of PVT performs better than PFP by 8.4%. This is owing to the additional reflectors, reflection of the solar incident rays to the receiver plate, which tend to rise in the temperature gradient of water inlet and outlet of the system. The thermal performance has been increased further by inserting the helix twisted tape with several twist ratios and the results are also presented. The minimum twist ratio 3 provides a higher heat transfer rate and friction factor owing to the increase in the hydraulic length and swirl flow. The experimental Nusselt number and friction factor are correlated and the deficiency falls ±6.44% and ±11.91%, respectively.     

Monthly optimum inclination of glass cover and external reflector of a basin type solar still with internal and external reflector

In this report, we present a theoretical analysis of a basin type solar still with internal and external reflectors. The external reflector is a flat plate that extends from the back wall of the still, and can presumably be inclined forwards or backwards according to the month. We have theoretically predicted the daily amount of distillate produced by the still throughout the year, which varies according to the inclination angle of both the glass cover and the external reflector, at 30°N latitude. We found the optimum external reflector inclination for each month for a still with a glass cover inclination of 10-50°. The increase in the average daily amount of distillate throughout the year of a still with inclined external reflector with optimum inclination in addition to an internal reflector, compared to a conventional basin type still was predicted to be 29%, 43% or 67% when the glass cover inclination is 10°, 30° or 50° and the length of external reflector is half the still’s length.     

大型桁架面天线的机电耦合优化设计

该文针对桁架面天线结构优化设计中的机电分离问题,将天线表面的微小变形表示为口径场的相位变化,得到包含结构因素的天线远场耦合计算公式,通过实验验证了该耦合公式的有效性和正确性。利用该公式将电性能指标引入传统的天线结构优化中,建立了以天线重量或电性能为优化目标,以结构强度和多种电性能变化量为约束的机电耦合优化模型,可以在天线结构设计过程中直接考察天线的主要电性能(包括增益、副瓣、波瓣宽度、指向精度等),同时避免了单一使用天线面精度的预估电性能的不足。通过某8 m天线的仿真结果表明了该耦合优化模型的优点。     

角反射天线特性的研究

用镜象法和矩量分析法对角反射天线的特性分别进行了研究。并加比较，表明二者结果相近；对于无法用镜象法分析计算的任意张开角反射天线问题，则仍可用矩量分析法近似计算解决。     

Mitigating the non-uniform illumination in low concentrating CPCs using structured reflectors

One problem in concentrating photovoltaic systems without active cooling is the formation of hot spots on the solar module cells. These hot spots are a result of uneven concentration of radiation within the solar module cells. The overall effect of concentrated heating is the reduction in the fill-factor of the solar module cell and the subsequent decrease in the overall efficiency of the system. In this paper, we investigate one alternative of improving the performance of a low concentrating photovoltaic system using semi-diffuse rolled reflective elements. Our results indicate that rolling marks on the reflector aligned parallel to the plane of the solar module cell improve the performance of the photovoltaic system.     

一种性能改进了的大张角四脊型超宽带馈源的研制

超宽带馈源在通信和射电天文等领域有着极高的应用价值。四脊喇叭作为宽带馈源的一种重要形式,存在着反射损耗性能较差,方向图随频率波动严重,照明张角难以拓展等诸多缺陷。本文基于国际上已有的研究基础,设计了一款工作于1.2~6.8 GHz的双极化大张角四脊型超宽带馈源。该设计方案对脊片部件采用了"削出倒角"、"厚度赋形"和"脊片外延"的改进措施,显著改善了馈源在低频段的反射损耗性能,同时也拓展了照明张角,使其能够更好地应用在大张角主焦照明的场合。实测结果显示出,该超宽带馈源的带宽和反射损耗性能均略优于国外样机。在边缘照明角为68°的大张角情况下,该馈源依然可以在1.2~6.8 GHz的带宽(相对带宽5.67:1)内达到低于-10 dB的反射损耗,其中在2.5~5.3 GHz内的反射损耗低于-15 dB。而且,该馈源在E面和D面的-12 dB边缘照明角随频率的波动小于20°。     

反射式强度型光纤传感器在微小位移精密测量中的应用

简要介绍反射式强度型光纤传感器的工作原理及各组成部分的作用。选择合适的光源、光纤对、检测器，对反射率不同的被测物进行位移测量，通过分析数据可以得到相应的位移测量参数；并分析了发送光纤与接收光纤轴间距对输出的影响。在实际测量中，可参照分析结果，根据被测物的情况选取合适的测量点。     

LCOS投影光源反射器的特性要求与玻璃系统的选择

根据液晶显示投影电视光学系统的结构，介绍了其投光系统中玻璃材质反射器应满足的特性要求，以及适用于该反射器的基础玻璃系统，提出适合选用的微晶玻璃系统。