频率可切换的矩形缝隙环频率选择表面

基于金属屏上周期排列的缝隙单元结构的通带特性,提出矩形缝隙环(Rectangular Slot Ring,RSR)加载短路线的单元结构实现频率可调频率选择表面(Frequency Selective Surface,FSS).谐振缝隙单元开路与短路时相对应的谐振频率分别为13 GHz和15 GHz.RSR-FSS选用Rogers RO4003介质作为基板,按照12×12的方阵进行周期排列,利用全波电磁仿真软件CST对其进行了电磁传输特性仿真.最终,通过实验验证了该频率选择表面在Ku波段通过连通和断开短路线可以进行频率的切换.     

高分六号遥感卫星新增波段下的树种分类精度分析

高分六号卫星具有覆盖广、多种分辨率、波段多的优势,能为遥感解译提供更丰富的信息。为探究高分六号卫星新增波段在森林树种识别上的应用,本文以覆盖根河市阿龙山林业局的一期高分六号宽幅影像为数据源,基于特征优化空间算法（Feature Space Optimization,FSO）和最大似然分类法,分别利用高分六号的前4个波段和所有波段（8波段）的光谱、纹理等特征进行了森林树种分类,并逐一添加新增波段特征确定了各波段的贡献率排名。结果表明：在加入了优选出的均匀性纹理、均值纹理和角二阶矩纹理3种纹理特征后,前4波段和8波段的分类精度比只基于光谱特征时的精度分别高出13.23%和24.63%;利用8波段信息比只利用前4波段在基于光谱特征上的精度高11.88%,在基于光谱+纹理特征上则高23.24%;基于8波段光谱+纹理特征的树种分类精度最高,达到68.74%,新增4波段的贡献率排名为B6>B5>B8>B7,说明新增红边波段对于本次树种分类试验的贡献率最高,能为北方树种识别提供有效帮助。     

低温氮吸附法测试煤中微孔隙及其意义

用低温氮吸附法测试了26个煤样的微孔隙,并对结果作了分析,得出以下认识:低温氮吸附法测出的最小孔的直径只有0.6nm,有利于更深入地了解煤的微孔隙特征;超微孔比微小孔所占比表面积大得多,占主要地位;煤层中吸收状态的甲烷应引起重视,游离、吸附状态的甲烷比通常认为的要少。     

黄山顶大气气溶胶吸收和散射特性观测分析

采用光声黑碳仪（PASS）2008年5～7月在黄山光明顶的连续观测资料,分析了该地区大气气溶胶吸收和散射系数变化特征及其与气象因子的关系。分析结果表明：在相对干燥的条件下（相对湿度小于60%）吸收散射系数日变化明显,总体上白天大,晚上小;相对湿度与吸收和散射系数有很强的正相关性,相关系数分别为0.87和0.80,而风速与散射吸收系数则呈现负相关关系,吸收系数、散射系数与风速的相关系数分别为-0.53和-0.78;湿清除使大气气溶胶的吸收和散射系数明显降低;与在平原地区的南京相比,黄山山顶的吸收和散射系数日变化趋势与南京相反,且数值比南京小一个量级。     

巯基棉富集分离—冷原子吸收法测定天然水中痕量汞

用巯基棉富集水中痕量汞,用饱和氯化钠的盐酸溶液解吸,冷原子吸收法测定。当水样取１ Ｌ时,最低检测浓度可达０－００３ μｇ／Ｌ,方法相对标准偏差为３－８ ％ ～６－９ ％ ,巯基棉汞平均回收率为９１－１％ 。该法操作简单、快速、富集倍数大,适用于天然水中痕量汞的分析。     

点吸收式波浪能俘获装置结构优化方法研究

根据布设海域波浪能资源特征,对点吸收式波浪能装置结构进行优化,可有效提高装置的能量俘获效率。本文以威海褚岛北部海域为装置布设目标海域,在对该海域波浪资源特征进行统计分析的基础上,计算得到装置的直径,同时利用数值软件计算出多组工况下点吸收装置吃水深度和装置固有周期的对应关系,并利用统计学方法得出装置固有周期随吃水深度的变化规律,进而分析得出装置在该海域的最佳设计吃水深度,为点吸收波浪能装置结构优化设计提供了新的思路。该方法对于其他技术类型波浪能装置的结构优化设计同样具有借鉴意义。     

Cosmic rays and changes in atmospheric infra-red transmission

Recent work by Aplin and Lockwood (2013) [1] was interpreted by them as showing that there is a multiplying ratio of order 10¹² for the infra-red energy absorbed in the ionization produced by cosmic rays in the atmosphere to the energy content of the cosmic rays themselves. We argue here that the interpretation of the result in terms of infra-red absorption by ionization is incorrect and that the result is therefore most likely due to a technical artefact.     

Constraints on variations of mp/me based on UVES observations of H2

This article summarizes the latest results on the proton‐to‐electron mass ratio μ derived from H₂ observations at high redshift in the light of possible variations of fundamental physical constants. The focus lies on UVES observations of the past years as enormous progress was achieved since the first positive results on Δμ /μ were published. With the better understanding of systematics, dedicated observation runs, and numerous approaches to improve wavelength calibration accuracy, all current findings are in reasonable good agreement with no variation and provide an upper limit of Δμ /μ < 1 × 10^–5 for the redshift range of 2 < z < 3. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

吸积双星脉冲星EXO2030+375中回旋吸收线的迹象

本文作者首次发现了EXO 2030+375的回旋吸收线迹象.这是迄今唯一一个同时有用回旋吸收线直接测量的磁场数据和用吸积演化方法间接测量的中子星磁矩数据的X射线脉冲星.两种测量方法的结果有很大差别,本文提出了可能导致这种差别的物理机制.     

Chemical evolution of the high redshift galaxies

We have tried to determine the rate of chemical evolution of high redshift galaxies from the observed redshift distribution of the heavy element absorption systems in the spectra of QSOs, taking into account the evolution in the intensity of the metagalactic UV ionizing radiation background, the radius and/or the co-moving number density of, and the fraction of mass in the form of gas in, the absorbers. The data for both the Lyman limit systems and the C IV systems have been fitted simultaneously. It seems that the abundance of carbon has possibly increased by about a factor of 5 to 20 from the cosmic time corresponding to the redshift ≃ 4 to 2. The data also suggest that either the radius or the co-moving number density of the galaxies increased with redshift up to z = 2.0 and decreased slowly thereafter. The total mass of the halo gas was higher in the past, almost equal to the entire mass of the galaxy at z = 4. The hydrogen column density distribution for Lyman limit systems predicted by the model is in agreement with the observed distribution.