Thermal considerations on the design and operation of lens ducts

In this paper, heat effects due to powerful pump beam in the lens duct delivery system is investigated and subsequent thermal effects are described. Temperature raise in the device, thermal loading, and material considerations for the lens ducts fabrication are reported. For an absorbed intensity of 10 W/cm² in a 4 cm-long lens duct, the temperature difference between the midpoint and its faces, for a lens duct made from borosilicate is 7.05°C, for sapphire 4.01°C, and for synthetic fused silica is the smallest value of 0.54°C. For a typical absorbed intensity of 1.4 W/cm² in a 4 cm-long lens duct, with a steady-state time constant of 120 s, the fractional thermal loading is 1.98% for BK-7, 1.89% for sapphire, and only 0.16% for synthetic fused silica. By considering different glass materials, the overall results show that synthetic fused silica is superior to some other materials for the fabrication of a lens duct. The reported analytical method and the results of parametric studies can be helpful in material selection and construction of an effective lens duct.     

探地雷达最优工作信号与脉冲波形畸变的整形技术

利用信号检测理论，在雷达接收天线端信号的信噪比最大时，推出浅层地下目标探测雷达的工作信号形式是基带脉冲。该脉冲波是媒质参数、目标特性和目标埋深的函数。脉冲波在有耗媒质中传播时，既要引起幅度的衰减又要产生波形失真。通过分析波形失真的原因，提出了一种对失真波形进行整形的方法。     

X波段谐波混频频率合成器的设计

本文主要介绍利用谐波混频技术设计的X波段频率合成器。该频率合成器具有跳频速度快、输出频带宽、相噪低、体积小、重量轻等特点 ,同时没有倍频环节 ,降低了系统的设计难度 ,便于实现。     

时间序列优选法在棉铃虫发生趋势超长期预测中的应用

本文探讨了时间序列优选法在三代棉铃虫发生趋势超长期预测中的应用方法。     

高性能K波段宽频带检波器

介绍了高性能的宽带检波器的CAD设计方法及测试结果。该检波器采用波导E面集成电路形式 ,通过对极鳍线实现波导微带过渡 ,采用高频电磁场仿真软件和微波电路CAD软件完成该检波器的设计。测试结果表明 ,该设计方法实现的检波器具有优良的性能     

优质课电视片制作的设计与策划

分析优质课的课型 ,把握优质课的特色 ,有针对性地做好优质课电视片设计制作前的准备工作。阐述了在开机拍摄前了解教师教学风格、了解学生特点、了解教学环境、了解课型结构的重要性 ,提出了拍摄时机位设置、光线处理、声音拾取的技巧与方法以及编辑制作中的要求。     

基于Web的eDFM电路设计技术

在对可制造设计的基本理念进行初步介绍的基础上 ,对应用先进电气互联技术的电路PCB和整机接线图的可制造设计进行了详尽的描述     

Removal of Phenol Dyes Using a Photocatalytic Reactor with SnO2/Fe3O4 Nanoparticles

In this study, we present kinetics of phenol dyes removal by SnO₂/Fe₃O₄ nanoparticles in a photocatalytic reactor for optimization of this process. The effect of different concentrations of SnO₂ 5, 10, 15, 20% w/w on the photocatalytic reactor during removal of phenol red was investigated. The SnO₂/Fe₃O₄ nanoparticles were synthesized by core–shell method. The results of XRD and TEM showed the successful synthesis of these nanoparticles. Several other methods were applied to synthesis of these nanoparticles but none of them succeeded. This process composed of two-stage. The first stage was absorption by iron oxide nanoparticles and second stage was photocatalytic by tin oxide nanoparticles that followed pseudo-second-order kinetic and first-order kinetic, respectively. Optimization of this process was done corresponding to the parameters affecting the process with design expert software. In order to determine the optimal values of each of the parameters and the optimal conditions of the process, parameters were introduced to response surface methodology.     

厚铜多层印制板的工程设计与生产控制

文章分析了厚铜多层印制板的主要制作难点,如内外层厚铜线路制作、厚铜多层印制板压合、厚铜多层印制板钻孔、厚铜多层印制板阻焊印刷等。针对主要制作难点,文章介绍了如何从板材和半固化片选用,压合叠层结构优化,内层线路图形设计补偿,钻孔设计,阻焊设计等工程设计手段来提高产品可靠性,以及介绍了重要制作工序的生产控制要点,有效提高了厚铜多层印制板的品质可靠性。     

卫星导航抗干扰专用芯片后端版图设计

随着电磁环境的日益复杂,卫星导航接收系统的抗干扰性能要求越来越高。在小型卫导接收系统的抗干扰设计中,体积和功耗已经成为最大的限制因素,抗干扰芯片的设计已成为解决该问题的有效途径。本文基于SoC Encounter后端版图设计工具,通过布局规划、电源设计、标准单元放置、时钟树综合及优化、布线等后端版图设计流程,完成了一款卫星导航抗干扰专用芯片的后端版图设计工作。