扁椭球形雨滴和冰粒后向散射实验与理论研究

本文介绍了对扁椭球形雨滴和冰（雹）粒散射能力的实验模拟和测量技术，报告了一个系列扁水(冰)椭球后向散射截面的实验测量结果；并用扩张边界条件法(EBCM)计算出相应的理论值，用Mie公式计算出等容积球形后向散射截面。将实验结果与理论计算作了综合对比分析，得到了若干有用的结论。     

基于OpenSees的RCS组合框架结构抗震性能模拟分析

选取已有钢筋混凝土柱—钢梁组合结构（RCS）框架的低周期反复试验数据,采用地震工程开源模拟软件OpenSees对其进行有限元模拟,对比骨架曲线与滞回曲线,试验结果与有限元结果吻合较好。随后考察弯矩放大系数（Mc/Mb=0.86、1.48、2.04）、柱轴压比（n=0.06、0.2、0.3、0.6、0.8）对抗震性能的影响,得到了各参数下框架的滞回曲线、骨架曲线和各特征阶段的荷载与位移值。分析了框架的破化过程、延性与强度退化。结果表明：RCS组合框架滞回曲线饱满,具有良好的变形及耗能能力;随着弯矩放大系数的减小、柱轴压比的增大,框架的水平极限承载力降低、屈服状态提前、位移延性降低。分析结果可供有关研究或工程应用参考。     

RCS analysis in the detection of a generic missile target with sea clutter background

The detection of a missile target in heavy sea clutter is a significantly challenging problem due to the clutter effects. In this paper, the radar cross sections (RCS) of a pre-assumed generic missile model is computed with multilevel fast multi-pole algorithm (MLFMA), while the RCS of ocean surface is computed by a more reduced form of the fractional Weierstrass scattering model proposed here. At last, the computed RCS of missile model is compared with that of sea surface, and then the comparisons of missile-to-ocean RCS ratios of different incident angles, incident frequencies, and polarization patterns are also presented. The discussion and comparisons of RCS of the missile and ocean surface can help us to plan and design a radar system in the application of detection of a missile target or other analogous weaker targets in the strong sea clutter background.     

基于完好性的石油平台动力系统备品备件研究

基于完好性理论,提出了埕岛油田动力系统的备品备件配置策略,为复杂可维修系统的备品备件配置提供了一个通用的方法。     

微波目标散射特性全要素测量试验

合成孔径雷达SAR(Synthetic Aperture Radar)以其全天时全天候的观测能力在地表目标识别、灾害监测等领域得到了越来越多的重视,高分辨率、全极化等各类先进SAR载荷卫星的发展日新月异.相对而言,微波与地物目标的相互作用机理仍有待深入研究.在可控无电磁干扰的测试环境下开展典型目标微波特性测量实验,可以...     

基于5G RCS UP1.0标准的天气消息支撑系统设计与实现

气象短信服务在气象部门已有十多年的历史并有较广的覆盖面,由于一直以来受运营商传统短信网关的技术能力限制,仅能提供70个字的文字服务。2020年随着三大运营商联合发布《5G消息（5GMC）白皮书》,推出了RCS（Rich Communication Suite, 富媒体通信）,该技术具备融合语音、消息、视频、社区网络等多种功能,为传统短信业务的全面升级提供了技术支撑。本文立足现阶段手机终端普遍支持的RCS UP1.0标准,研究建立“5G天气罗盘制作发布支撑系统”提供以图片、视频等形式的服务内容将天气消息多媒体化,并通过Chatbot的NFS（Network File System）回落技术实现非5G用户以彩信回落的方式接收5G消息,对传统气象短信进行迭代升级,取得了较好的运行效果。     

RCS的频率步进连续波测试技术研究

采用频率步进连续波体制进行RCS测试是一种新技术,本文具体研究了频率步进连续波测试系统的信号处理模型,分别对回波数据在IFFT处理中的补零点数、数据截断宽度和窗函数选取等方面进行深入分析,最终通过系统地实验验证,表明信号处理工具的有效应用,使得频率步进连续波RCS测试技术具备良好的测试精度和较宽频段的目标特性信息。     

Tree-ring growth curves as sources of climatic information

Regional growth curves (RGCs) have been recently used to provide a new basis for removing nonclimatic trend from tree-ring data. Here we propose a different use for RGCs and explore their properties along two transects, one meridional and the other elevational. RGCs consisting of mean ring width plotted against cambial age were developed for larch samples from 34 sites along a meridional transect (55-72°N) in central Siberia, and for 24 sites on an elevational gradient (1120 and 2350 m a.s.l.) in Tuva and neighboring Mongolia at approximately 51°N. There are systematic gradients of the parameters of the RGCs, such as I₀-maximum tree-ring width near pith, and I_min, the asymptotic value of tree-ring width in old trees. They are smaller at higher latitude and elevation. Annual mean temperature and mean May-September temperature are highly correlated with latitude here, and hence RGC parameters are correlated with these climatic variables. Correlations with precipitation are more complex, and contradictory between meridional and elevational transects. The presence of a similar gradient in the elevational transect is consistent with temperature being the causal factor for both gradients, rather than, for example, latitude-dependent patterns of seasonal photoperiod change. Taking ring measurements from collections of relict and subfossil wood, the RGC-latitude and RGC-temperature relationships are used to estimate paleo-temperatures on centennial time scales. These estimates are consistent with earlier “traditional” dendroclimatic approaches, and with independent information on the northern extent of forest growth in the early mid-Holocene. It may be possible to use this same approach to make estimates of century-scale paleo-temperatures in other regions where abundant relict wood is present.     

基于时域有限差分法的雪花粒子群多次散射研究

为精确利用雷达回波反演雪花粒子的微物理参数,建立满足指数分布的非球形雪花粒子群模型,在94GHz频率下利用XFDTD软件计算电磁波不同入射方向下粒子群的后向散射截面,并与简单相加作比较,结果表明:同一入射方向下,粒子群多次散射效应下的后向散射截面均大于简单相加的结果;不同入射方向下,粒子群的后向散射截面表现出很大的差异。因此雷达实际探测中必须考虑多次散射和入射电磁波的方向。