地网是多普勒甚高频全向信标(Doppler very high frequency omni-directional range,DVOR)天线系统的重要组成部分,其常规架高及直径分别为5 m左右和30.5 m。随着城市化进程的持续推进,越来越多DVOR台站的环境正在急剧恶化,一些民航单...地网是多普勒甚高频全向信标(Doppler very high frequency omni-directional range,DVOR)天线系统的重要组成部分,其常规架高及直径分别为5 m左右和30.5 m。随着城市化进程的持续推进,越来越多DVOR台站的环境正在急剧恶化,一些民航单位尝试将地网架高和地网直径同时增大,以减少周围建筑物对DVOR信标辐射性能的影响,但这些非常规架设地网对DVOR台辐射特性的影响缺乏理论分析,对这类地网的架设缺乏理论指导。结合DVOR系统的天线特征及馈电特点,基于物理光学法获得了包括直射场、地面反射场及地网散射场在内的DVOR辐射场,在此基础上,依据国际民航组织(International Civil Aviation Organization,ICAO)“附件10”的要求,给出了非常规架设地网时DVOR顶空盲区,以及不同飞行高度所对应的最远水平作用距离之内场强分布的求解方法,并进行了相应仿真实验。实验结果表明,若地网直径保持常规的30.5 m,对于非常规架高地网的DVOR信标,其垂直辐射特性不会出现多瓣现象,顶空盲区不会受到影响,在ICAO规定的不同飞行高度所对应最远水平作用距离之内的场强大小满足要求;但当地网架高增大到大于等于30 m时,即使将地网直径增大到50 m,也难以满足“附件10”规定的水平覆盖场强要求。研究成果可为非常规架设地网DVOR信标台的建设提供相应理论支持。展开更多
The different interactions between a chemosensor, 1-（naphthalen-2-yl）-3-（6-nitrobenzothiazol-2-yl）-thiourea （1）, and F, acetate （AcO-）, Cl-, and Br- anions have been investigated theoretically at the B3LYP/6-3...The different interactions between a chemosensor, 1-（naphthalen-2-yl）-3-（6-nitrobenzothiazol-2-yl）-thiourea （1）, and F, acetate （AcO-）, Cl-, and Br- anions have been investigated theoretically at the B3LYP/6-31＋G（d,p） level with the basis set superposition error （BSSE） correction. It was found that the high selectivity of compound 1 for F- can be ascribed to the ability of the anion to deprotonate the N-H fragment of the host sensor, while the chemosensor also has a strong affinity for AcO- by virtue of the formation of a hydrogen-bonded complex. Intramolecular charge transfer （ICT） causes the colorimetric signaling of compound 1 after interaction with F-/AcO. A study of substituent effects suggested that the O/NH- and O/S-substituted derivatives are also expected to be promising candidates for chromogenic F3AcO chemosensors.展开更多
文摘地网是多普勒甚高频全向信标(Doppler very high frequency omni-directional range,DVOR)天线系统的重要组成部分,其常规架高及直径分别为5 m左右和30.5 m。随着城市化进程的持续推进,越来越多DVOR台站的环境正在急剧恶化,一些民航单位尝试将地网架高和地网直径同时增大,以减少周围建筑物对DVOR信标辐射性能的影响,但这些非常规架设地网对DVOR台辐射特性的影响缺乏理论分析,对这类地网的架设缺乏理论指导。结合DVOR系统的天线特征及馈电特点,基于物理光学法获得了包括直射场、地面反射场及地网散射场在内的DVOR辐射场,在此基础上,依据国际民航组织(International Civil Aviation Organization,ICAO)“附件10”的要求,给出了非常规架设地网时DVOR顶空盲区,以及不同飞行高度所对应的最远水平作用距离之内场强分布的求解方法,并进行了相应仿真实验。实验结果表明,若地网直径保持常规的30.5 m,对于非常规架高地网的DVOR信标,其垂直辐射特性不会出现多瓣现象,顶空盲区不会受到影响,在ICAO规定的不同飞行高度所对应最远水平作用距离之内的场强大小满足要求;但当地网架高增大到大于等于30 m时,即使将地网直径增大到50 m,也难以满足“附件10”规定的水平覆盖场强要求。研究成果可为非常规架设地网DVOR信标台的建设提供相应理论支持。
基金supported by the Natural Science Foundation of Inner Mongolia Autonomous Region (2011ZD02)
文摘The different interactions between a chemosensor, 1-（naphthalen-2-yl）-3-（6-nitrobenzothiazol-2-yl）-thiourea （1）, and F, acetate （AcO-）, Cl-, and Br- anions have been investigated theoretically at the B3LYP/6-31＋G（d,p） level with the basis set superposition error （BSSE） correction. It was found that the high selectivity of compound 1 for F- can be ascribed to the ability of the anion to deprotonate the N-H fragment of the host sensor, while the chemosensor also has a strong affinity for AcO- by virtue of the formation of a hydrogen-bonded complex. Intramolecular charge transfer （ICT） causes the colorimetric signaling of compound 1 after interaction with F-/AcO. A study of substituent effects suggested that the O/NH- and O/S-substituted derivatives are also expected to be promising candidates for chromogenic F3AcO chemosensors.
