A microwave ceramic band-pass filter for mobile communications with new coupling structure

A surface mounted device (SMD) microwave ceramic band-pass filter for mobile communication with a new coupling structure is reported in this paper. In this filter, the external and internal coupling structures are fabricated on an alumina substrate and both resonators and coupling structures are placed into a metal house to cut off its radiation. The relationship between the coupling structures and the performance of filter is analyzed by high frequency structure software (HFSS) and the filter with the center frequency of 836.5 MHz, the bandwith of 40.0 MHz, the pass-band ripple of 0.1 dB and the insertion loss of 1.5 dB has been successfully designed and fabricated. The measured results show a good agreement with the simulation results. Foundation item: Supported by Sino-British Excellent Youth Scholar Foundation (2005362) and the Natural Science Foundation of Hubei Province (2008CDB315)     

光纤激光陀螺环形腔的优化设计

分析了有源环形谐振腔组成的光纤激光陀螺的精度与谐振腔特征参数的关系,采用单向泵浦光纤复合谐振腔结构的光学系统设计方案.在此结构上,对影响光纤激光陀螺理论精度的结构参数进行计算机数值仿真,详细讨论了系统参数的变化趋势对光纤激光陀螺理论精度的影响.初步仿真结果表明:选取合适掺铒光纤长度及泵浦功率可以有效提高理论精度,提高输入信号光强及选择合适的输出耦合器的耦合比,可进一步提高陀螺的理论精度.     

用树轮碳同位素年序列重建大气二氧化碳浓度

大气圈ＣＯ２浓度及其同位素组成是不断变化的。植物在同化大气ＣＯ２过程中产生碳同位素分馏,因此,树轮中稳定碳同位素比值（＾１３Ｃ／＾１２Ｃ）不仅是重建古气候的工具,也是过去大气ＣＯ２浓度变化的敏感指标器。利用采自浙江西天目山的两株柳杉树轮稳定碳同位素（δ＾１３Ｃ）组成年序列,对１９世纪中叶以来大气ＣＯ２浓度变化进行重建,其重建值与大气ＣＯ２浓度的实测值较吻合。     

基于传输线理论的零阶谐振器FDTD分析与优化

通过FDTD数值仿真,完全由电路理论所描述的零阶谐振器特性得到了证实。通过对电路参数的研究可以更好的定性分析零阶谐振器特性:谐振频点的数量取决于单元结构的个数,而零阶谐振频率是不依赖于结构长度的。改变短路电感的长度及金属导孔的位置,可以调整零阶谐振频率。通过对结构的进一步优化,可以获得一个更小的1.5个单元结构零阶谐振器模型,该模型在1.9GHz频率上具有较好的无负载品质因数Q。     

Systemic Human Relations in Dynamic Equilibrium

This paper reports on a breakthrough in thinking based on 33 years of field practice-based inquiry and previously published studies. It brings together several bodies of established and emerging thought including systems thinking, epistemology, psychology and sociology, in a way of thinking about the living fabric of complex human systems-in-process. It is offered here as a kind of transdisciplinary ‘Rosetta stone’ to those working around the world with one or more of these bodies of thought as a way of making some critical connections between them. In summary, an integrating ‘mental architecture’ is proposed whereby inquiry (research as an evaluative dynamic act of seeking) may be seen as the way by which living (notably human) systems come alive, and which is incorporated, organ-ised, ‘structured’ and relationally embodied in an individual and their psychological mind as personal process, and in social collectivities and their sociological organisation as cultural process.

多频带通滤波器技术(英文)

结合笔者及其课题组多年来的研究成果,集中介绍了近几年出现的多频带通滤波器的设计和实现技术———为得到各通带频率和带宽都可控的多频滤波器,利用多通带谐振器设计双频及三频滤波器;为减小滤波器尺寸,利用阶跃阻抗谐振器设计双频及三频滤波器;为方便控制通带频率,基于枝节线加载谐振器设计双频及三频滤波器;为获得更好的带外特性和更多通带,基于组合谐振器设计三频及四频滤波器.文中最后介绍了基于多枝节加载谐振器的高阶双频滤波器的设计方法.在保持第一通带特性不变的前提下,该高阶双频滤波器的第二通带可以很方便地进行调节.     

穿孔板吸声结构的频率特性分析

分析了亥姆霍兹共鸣器的共振频率特性，导出了穿孔板吸声结构吸声的中心频率、频带宽度、上限频率及下限频率的估算公式，为设计、制作理想的穿孔板吸声结构提供了参考．     

紧凑型多陷波超宽带滤波器的设计

针对传统带阻单元构成滤波器存在陷波深度不足和阻带抑制较差的问题,提出一种加载开路枝节的多陷波超宽带滤波器。基于开路枝节线和阶跃阻抗谐振器理论,通过在超宽带滤波器多模谐振器上引入一对折叠开路枝节线产生2个陷波频段,这种特殊枝节实现的陷波抑制能力更强;在超宽带结构下方耦合阶跃阻抗谐振器产生第3个陷波频段,陷波深度更好。最终实现超宽带带通滤波器的中心频率为6.6 GHz,陷波频段相对带宽约为134%。仿真与实测结果表明,该滤波器工作带宽为2.2~11.2 GHz,实现了2.8~4.4 GHz,6.2~6.8 GHz和8.8~9.8 GHz 3个频段的陷波特性,可有效滤除C波段和WLAN频段信号对超宽带通信系统的干扰。满足超宽带系统对陷波滤波器插入损耗和带外抑制的要求。     

Stable isotopic compositions of precipitation events from Kathmandu,southern slope of the Himalayas

Investigation of temporal variations in the stable δ^18O and δD isotopes from Kathmandu＇s precipitation events shows that the relatively enriched δ^18O and δD values in the winter （the dry season, dominated by the westerlies） were positively correlated with temperature, indicating a temperature effect controlling the changes of δ^18O and δD. However, the δ^18O and δD values were depleted in the summer （the wet season, dominated by the Indian monsoon）, which were negatively correlated with precipitation amount, indicating an amount effect. In addition, the comparison of stable isotopes in precipitation from Kathmandu and Mawlong （near the Bay of Bengal） shows that the overall trends of δ^18O and δD values at Kathmandu generally approximate those at Mawlong. However, there remain many differences between the details of the isotopic changes at Kathmandu versus those at Mawlong. Compared with those at Mawlong, the further rainout effect and the more intense lift effect of the oceanic moisture by the high mountains resulted in the more depleted δ^18O and δD values in summer precipitation at Kathmandu. A deuterium excess and the local meteoric water lines reveal that evaporation at Kathmandu exceeds that at Mawlong. The data also show that the Indian monsoon activities at Mawlong are more intense than those at Kathmandu.     

基于ENG-TL零阶谐振器天线的多层波概念迭代法分析

针对有限元法、时域有限差分法具有吸收边界条件的不完整性、计算效率不高等缺陷,引入多层波概念迭代法(multilayer contribution of wave concept iterative process)有效地解决上述问题.利用该方法分析基于ENG-TL零阶谐振器天线的多层模型,通过对激励源所在平面电磁场与电流场的仿真,计算出S参数.该结果与HFSS仿真结果和参考文献结果进行对比,呈现良好的一致性,验证了该方法的准确性,丰富了对ENG-TL零阶谐振器天线的数值研究.