近空间被动双站SAR的成像性能分析

近年来,近空间受到了越来越广泛的关注。近空间飞行器兼具卫星和航空飞机的优点,能提供类似卫星的宽覆盖、长续航能力和飞机的快速响应能力,这为研究新体制遥感技术创造了条件。基于此,文章提出了一种基于近空间平台的被动双站合成孔径雷达(SAR)成像方法。首先,通过分析近空间被动双站SAR的空间几何模型,建立了其相应的SAR回波信号模型;然后,根据发射机和接收机对成像目标产生的多普勒效应,对近空间被动双站SAR成像的距离分辨率和方位分辨率进行了分析和仿真,并分析了近空间被动双站SAR存在的方位向调频率空变特性。最后,以接收机静止模式为例,对其成像处理进行了仿真。理论分析和仿真实验结果表明,近空间被动双站SAR是一种具有良好应用前景的遥感新技术。     

Progress on shelf and slope circulation in the northern South China Sea

Influenced by the seasonally reversed monsoons, water exchange through straits, and topography, the shelf and slope circulation in the northern South China Sea (NSCS) is complex and changeable. The typical current system in the NSCS consists of the slope current, South China Sea warm current (SCSWC), coastal current, and associated upwelling (in summer) and downwelling (in winter). This paper reviews recent advances in the study of NSCS shelf and slope circulation since the 1990s, and summarizes the roles of Kuroshio intrusion, the monsoons, topography, and the buoyancy effect of the Pearl River plume in the shelf and slope current system of the NSCS. We also point out some potential scientific issues that require further study, such as the dynamic connection between the internal basin and shelf areas of the NSCS, the persistence of the SCSWC in winter, the temporo-spatial characteristics of downwelling during winter in the NSCS, and its material and energy transport.     

寒区浅水湖冰生消特征及其影响因素

基于2019—2020期间在盘锦市含章湖利用浮式观测平台开展湖冰原型观测试验,分析不同因素对湖冰变化造成的影响.结果表明:99 d冰期内湖冰的生消过程可概述为:湖泊封冻(3 d)—稳定生长(62 d)—冰厚稳定(7 d)—加速消融(24 d)—破碎分解(3d).生长期冰厚的平均增长速率为0.4 cm/d,最大冰厚为30.7 cm;不同深度(5～17 cm)冰温对气温变化的响应存在滞后性,滞后时间为70～158 min,冰温与气温的最大相关系数为0.52～0.89;降雨过程造成冰面反照率由0.22降至0.09,影响了冰内温度以及冰下40 cm以内的浅层水温,但14 mm的降雨量并未引起表面冰厚增加;降雪过程造成冰面反照率由0.25升至0.90,同时阻碍了 5 cm以内的浅层冰温对气温变化的响应,但风速长时间大于8 m/s时会导致冰面积雪被吹散,冰面重新裸露;消融期冰厚的衰减过程呈抛物线趋势,存在显著的加速过程,融化速率由0.3 cm/d逐渐增加到2.7 cm/d;湖冰生长期的冰底热通量均值为4.8 W/m~2;到消融期增加至8.1 W/m~2,为生长期的1.7倍;太阳辐射与湖冰边界侧向融化是导致湖冰加速融化的关键因素.本研究填补了国内湖冰冻融全过程实测资料的空缺,为湖冰热力学模型的改进提供了科学支撑.     

一种改进的X荧光分析基体效应校正方法及软件实现

在能量色散 Ｘ 荧光谱分析中,使用罗兹方程法校正基体效应,存在一定的局限性。为了获得最佳校正效果,本文提出了一种改进的基体效应校正法。该法是以罗兹方程为基础,在校正模型中引入特散比,并加强待校正元素在模型中作用的一种经验系数法。为了能够快速地对地质样品进行批量分析,在 Ｗ ｉｎｄｏｗ ｓ９８ 平台上,运用 Ｖ Ｃ＋ ＋ ５．０ 工具编制了分析软件,由其完成全部校正分析过程。     

长白山聚龙泉温泉地温梯度和热流的估算

本项研究在野外完成了长白山聚龙泉温泉的测温测流工作;采集了相 应的温泉水样,对水样进行了常规分析,获得了K+、Na+、Ca2+、Mg2+、SO2-4、HCO-3、SiO2等组分结果。选取了4个温泉水样作为计算长白山聚龙泉温泉的热储的基本数据;使用玉髓温标公式初步计算了温泉热储的温度;根据Donaldson的管状模型,热流体的对流传输模型和无量刚的温度参数（由热储温度,地表泉口温度和地表平均气温计算）—涌水流量曲线的方法,参考了Rybach(1987)的一组曲线,估算了热水的循环深度（即热储深度）;使用地表温度、热储温度和热储深度,由热传导方程得到了长白山聚龙泉温泉地区的地温梯度, 估算了该地区的热流。     

核磁共振（NMR）高分辨成象

在磁共振成象（ＭＲＩ）中,对各种不同情况如何获取高分辨图象是一个比较复杂的技术问题,与很多参数,因素有关,本文给邮了图象分辨率和图象信噪比,机器灵敏度等参数的制约关系,及在理想情况下分辨率和场梯度,采集时间的定量关系,针对旨在观察单细胞的ＮＭＲ显微镜成象,分析了扩散对极限分辨率（μｍ）的限制。针地人体定域高分辨成象介绍了几种避免图象分析叠（ａｌｉａｓｉｎｇ）的方法,阐述了高分辨成象与脉冲序列的关系     

褐藻乳酸菌发酵奶饮料的研制

利用无腥味发酵优良的乳酸菌褐藻（海带）凝固奶,进行糖酸配比及添加稳定剂的正交设计试验,确定搅拌型褐藻奶饮料的最佳配比为凝固奶３０％、蔗糖１０％、酸味剂０．２５％、复合稳定剂０．２５％。采用科学的工艺生产,并对产品营养成分进行分析,结果表明,褐藻乳酸菌发酵奶是一种风味好、营养价值高、具有保健功能的饮料。     

Distribution and characterization of Chilean populations of the brine shrimp Artemia (Crustacea, Branchiopoda, Anostraca)

Hypersaline habitats in Chile, from marine solar salt pans to saline lagoons and pools in Andean salars, were prospected in search of Artemia populations. These saline ecosystems were characterized through physico-chemical parameters and ionic composition of their brines. Biometrics of cysts and nauplii, as well as morphometrics by using multivariate discriminant analysis for adult specimens evidenced that the Chilean populations of brine shrimp belong to A. franciscana. Cross-breeding results supported the former hypothesis of conspecific Chilean populations, and their differences with A. persimilis, also endemic to the New World, but restricted to Argentinean sites.     

一种基于不同表面强迫方式对CFSR表面通量资料进行修正的方法探讨

海表面温度(SST)的变化是海气相互作用的重要体现，SST的准确模拟也是海洋内部温度模拟的基础。基于区域海洋模式，本文通过对比分析两种强迫方式对SST的模拟效果，诊断了各辐射场对SST模拟效果的贡献，基于EOF分析法提出了一种针对CFSR表面大气强迫辐射数据的修正方案，并获取一套高频辐射场修正数据。数值对比试验结果显示，利用COARE 3.0公式计算所得表面强迫的方式模拟的SST结果更好，其均方根误差比直接强迫方式降低约39%；潜热辐射差异是两种强迫方式对SST模拟效果差异的主要原因，感热辐射差异次之，同时对两者进行修正可以显著改进SST的模拟效果；而长波辐射的修正则对冬季的SST模拟效果改善比较明显，但贡献仍弱于潜热辐射。相对于海洋模式而言，准确可靠的大气强迫数据的选择要优于强迫方式的选择。     

Analytical SuperSTEM for extraterrestrial materials research

Abstract— Electron‐beam studies of extraterrestrial materials with significantly improved spatial resolution, energy resolution, and sensitivity are enabled using a 300 keV SuperSTEM scanning transmission electron microscope (STEM) with a monochromator and two spherical aberration correctors. The improved technical capabilities enable analyses previously not possible. Mineral structures can be directly imaged and analyzed with single‐atomic‐column resolution, liquids, and implanted gases can be detected, and UV‐VIS optical properties can be measured. Detection limits for minor/trace elements in thin (<100 nm thick) specimens are improved such that quantitative measurements of some extend to the sub‐500 ppm level. Electron energy‐loss spectroscopy (EELS) can be carried out with 0.10–0.20 eV energy resolution and atomic‐scale spatial resolution such that variations in oxidation state from one atomic column to another can be detected. Petrographic mapping is extended down to the atomic scale using energy‐dispersive X‐ray spectroscopy (EDS) and energy‐filtered transmission electron microscopy (EFTEM) imaging. Technical capabilities and examples of the applications of SuperSTEM to extraterrestrial materials are presented, including the UV spectral properties and organic carbon K‐edge fine structure of carbonaceous matter in interplanetary dust particles (IDPs), X‐ray elemental maps showing the nanometer‐scale distribution of carbon within GEMS (glass with embedded metal and sulfides), the first detection and quantification of trace Ti in GEMS using EDS, and detection of molecular H₂O in vesicles and implanted H₂ and He in irradiated mineral and glass grains.