新型平面树状分形偶极子贴片天线的设计

提出了一种采用弧形分支的新型树状分形偶极子天线,简要介绍了树状分形天线的研究进展,设计了一种新型树状分形天线,并采用一种简单的巴伦馈电结构.二阶分形天线与0阶相比,工作频率下降了37.5%.对二阶分形天线进行了实物加工与测量,实验结果与仿真结果吻合较好.     

Interfacial reaction and shear strength of SnAgCu-xNi/Ni solder joints during aging at 150 °C

The interfacial microstructure and shear strength of Sn3.8Ag0.7Cu-xNi (SAC-xNi, x = 0.5, 1, and 2) composite solders on Ni/Au finished Cu pads were investigated in detail after aging at 150 °C for up to 1000 h. The interfacial characteristics of composite solder joints were affected significantly by the weight percentages of added Ni micro-particles and aging time. After aging for 200 h, the solder joints of SAC, SAC-0.5Ni and -1Ni presented duplex intermetallic compound (IMC) layers regardless of the initial interfacial structure on as-reflowed joints, whose upper and lower IMC layers were comprised of (CuNi)₆Sn₅ and (NiCu)₃Sn₄, respectively. Only a single (NiCu)₃Sn₄ IMC layer was ever observed at the SAC-2Ni/Ni interface on whole aging process. Based on the compositional analysis, the amount of Ni within the IMC regions increased as the proportion of Ni addition increased. The IMC (NiCu)₃Sn₄ layer thickness on the interface of SAC and SAC-0.5Ni grew more slowly when compared to that of SAC-1Ni and -2Ni, while for the (CuNi)₆Sn₅ layer the reverse is true. Except the IMCs sizes are increased with increased aging time, the interfacial IMCs tended to transfer their morphologies to polyhedra. In all composite joints testing, the shear strengths were approximately equal to non-composite joints. The fracturing observed during shear testing of composite joints occurred in the bulk solder, indicating that the SAC-xNi/Ni solder joints had a desirable joint reliability.     

边缘抽运非对称Yb:YAG盘片激光器

为了对Yb:YAG固体盘片激光器进行简单高效的抽运,采用了边缘抽运的方式,使用LD阵列通过光束耦合装置对非对称Yb:YAG/YAG复合晶体进行抽运,获得了80%以上的抽运光吸收效率和较均匀的吸收分布;同时,为了避免高功率工作下晶体过热导致性能下降,对这种抽运结构的散热装置结构进行了理论分析和实验研究,自主设计了理论散热效率超过12W/(cm2·K)的微喷式散热系统,并进行了实验。在抽运吸收功率750W时获得了123W的连续光输出,斜率效率达到34.8%。结果表明,边缘抽运方法在LD抽运盘片激光器的研究中有着很好的应用前景。     

复合材料加工研究现状及激光在其加工中的应用

简要分析了当前国内外复合材料加工的研究现状和发展趋势,并介绍了复合材料的特种加工技术,重点阐述了激光加工复合材料,具体内容包括切削力、切削热和切削刀具材料及结构等方面的研究成果。综合分析后,对未来激光加工复合材料的发展作了展望。     

非辐射边馈电的宽带双层微带贴片天线

介绍了一种非辐射边馈电的宽带双层微带贴片天线单元,并对其参数特性进行了仿真研究,结果表明,通过在寄生贴片上开3～5个与极化方向相平行的缝,可有效抑制天线的交叉极化,同时改善天线的阻抗带宽。相比传统双层微带贴片,该天线单元的阻抗带宽可提高3%以上,而交叉极化指标相当。当该单元应用于阵列天线设计时,可简化馈电网络,便于实现宽带、高效、大扫描角的微带共面馈电天线阵。对X波段8×8单元实验小阵的测试结果表明,该天线在17.6%的频段内具有良好的交叉极化性能及较高的工作效率。     

一种新型C波段宽带圆极化贴片天线的设计

采用电磁仿真计算软件HFSS设计并仿真了一种工作于C波段宽带圆极化微带贴片天线。天线采用双馈点对圆形微带贴片进行馈电,实现圆极化;选用两层聚四氟乙烯玻璃纤维板作为介质,通过底层馈电网络由探针穿过中间地板层对上层圆形贴片进行馈电,在探针周围用环形槽将探针与地板进行隔离,并增加了天线的谐振点,从而进一步扩展了天线频带。结果表明天线的相对带宽约为30％,并且E面、H面3dB轴比角度均大于90°。     

矩形微带天线的设计及FDTD分析

根据理论计算和实际修正,设计出工作于1.79GHz的矩形微带天线。利用基于非均匀网格的时域有限差分方法对天线进行建模和仿真,并分析了天线的频率特性、远场辐射方向图以及阻抗特性和驻波比。     

一种具有宽带宽角特性的改进型准八木天线

准八木天线是由巴伦、辐射单元和引向器构成的一种微带天线,文中提出了一种具有宽带、宽角特性的改进型准八木天线。通过CST仿真分析软件,对振子双臂后折和利用矩形微带贴片对辐射单元进行改进的微带贴片式准八木天线进行仿真分析,仿真和实测结果显示,微带贴片式准八木天线在带宽达到40%频带内（8 GHz～12 GHz）,驻波比（VSWR）≤2,3 dB的波束宽度均能达到120°以上。     

CuAlO2 powder dispersed in composite gel electrolyte for application in quasi-solid state dye-sensitized solar cells

The use of delafossite CuAlO₂ (CAO) powder as an additive in composite gel electrolyte (CGE) of the quasi-solid state dye-sensitized solar cell (DSSC) is first reported. In order to achieve an improvement of power conversion and long-term performance of the quasi-solid state DSSC, different contents of CAO powder containing in CGE, a mixture of polyethylene glycol (PEG), iodide/tri-iodide (I⁻/I₃⁻) liquid electrolyte (LE) and 4-tertbutylpyridine (4-tBP), were used in the present study. The photocurrent density–voltage characteristic (J–V curve) and photovoltaic performance parameters of the cells, such as the short-circuit current density (J_sc), open-circuit voltage (V_oc), power conversion efficiency (η) and fill factor (FF) were investigated. The CGE containing the dispersed CAO powder exhibited high ionic conductivity due to the charge diffusion through free channels. The power conversion efficiency of the quasi-solid state DSSC was significantly improved by adding CAO powder to the CGE. The optimum CAO powder content in the CGE was 0.05 wt%. In this research, the power conversion efficiency was 1.71 times of the LE and 2.85 times of the CGE with no CAO powder adding. The quasi-solid state DSSC based on the addition of CAO powder to CGE had long-term stability better than the normal DSSC based on the LE.     

烧结矿添加硼-镁复合添加剂工业试验

在磁铁矿精矿粉的烧结配料中加入硼－镁复合添加剂,可显著提高烧结生产效率及烧结矿的质量。经２４ｍ ２ 烧结机烧结及１８０ｍ ３ 高炉冶炼工业试验表明：采用复合添加剂技术及相应工艺后,烧结机利用系数由１．５６５ｔ／ｍ ２·ｈ提高到２．０９３ｔ／ｍ ２ ·ｈ;燃料消耗由９２．３５ｋｇ／ｔ降低到５４．０４ｋｇ／ｔ;高炉利用系数由２．３１５ｔ／ｍ ３·ｄ 提高到２．９５５ｔ／ｍ ３·ｄ;入炉焦比由６３０．４３ｋｇ／ｔ降低到５１９．６９ｋｇ／ｔ。