Experimental Research on the Microwave Scattering Characteristics of Crude Oil Emulsification and Application

合成孔径雷达（Synthetic Aperture Radar，SAR）卫星传感器以其高效性、实时性、不受云雨干扰的优势在海面溢油监测中发挥着主力军的作用。目前，SAR溢油监测研究主要集中于溢油与疑似溢油的识别，针对原油乳化进程对微波后向散射特性影响方面的研究内容较少。 本文通过开展C波段全极化散射计原油乳化观测实验，研究原油乳化微波散射特性，结合机载高光谱成像光谱仪和三维激光扫描仪观测数据，以期在SAR监测原油乳化、合理评估溢油量方面有所突破。主要研究内容为：（1）研究原油乳化对后向散射系数（Normalized radar cross section，NRCS）的影响。（2）基于实测油膜粗糙度、含水率，通过散射理论模型模拟乳化进程中的油膜NRCS并与实测数据对比，探究原油乳化散射机制。（3）通过分析油膜与近邻海水后向散射系数差值（0）、阻尼比（Damping ratio，DR）以及同极化比（Co-polarization ratio，CPR）随原油乳化进程的变化，定量研究原油均匀乳化进程中反映原油乳化程度的微波散射敏感参数。（4）基于定量原油均匀乳化观测数据，探究原油乳化进程中油膜厚度与微波散射溢油敏感参数的关系；基于自然乳化观测实验中全极化散射计与机载高光谱联合观测数据，构建油膜NRCS与油膜厚度之间的经验关系并验证。（5）利用星载SAR卫星影像，将原油乳化微波散射溢油敏感参数与油膜厚度微波散射经验公式应用于海上溢油监测实例。 主要结论如下：（1）乳化物的形成改变原油微波散射特性，乳化一定程度增大油膜NRCS。（2）利用实测的油膜表面粗糙度与含水率基于散射理论模型模拟油膜NRCS，探求了原油乳化后向散射机制，油膜NRCS变化受油膜介电常数和表面粗糙度的共同调制，且介电常数的影响占主导地位。（3）基于定量原油均匀乳化进程数据分析发现0与DR能够一定程度反映油膜乳化程度，且在VV极化下最显著。（4）初步构建了接近自然溢油状态下原油与乳化油混合的油膜厚度估算经验公式，结果显示随0的减小油膜厚度增加。（5）利用星载SAR卫星影像数据，将原油乳化微波散射敏感参数0、DR与接近自然溢油状态下构建的油膜厚度经验公式应用于海上溢油实例，成功解释了海面溢油（重质油）油膜相对厚度的分布与乳化特征，为精确海上溢油遥感监测提供了实验参数和方法支持

Identification of crude oil and emulsified crude oil based on microwave scattering experiment

The leaked of crude oil will form emulsions of different concentrations in the process of weathering and migration, which poses a serious threat to the marine ecological environment. Synthetic aperture radar (SAR) plays a major role in the observation of the extent of oil spills on the sea surface which is not affected by rain and clouds and has the advantage of day and night monitoring. However, there are some deficiencies in the identification of emulsified crude oil still exist. In this paper, the natural emulsification of crude oil was observed by C-band full-polarization microwave scatterometer, emulsification process of crude oil simulated by manually prepared oil samples with different moisture content was also observed to study the change of the normalized radar cross section (N_(RCS)). The experimental results show that N_(RCS) of emulsified crude oil is higher than that of crude oil, and the higher the emulsification degree is, the higher the N_(RCS) of oil film is. N_(RCS) differences between oil and water (△sigma~0) and damping ratio (D_R) can identify emulsified and non-emulsified crude oil, reflect the change of the degree of oil film emulsification, and in VV polarization is the best

Prediction of Energy Resolution in the JUNO Experiment

International audienceThis paper presents the energy resolution study in the JUNO experiment, incorporating the latest knowledge acquired during the detector construction phase. The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV. To achieve this ambitious goal, significant efforts have been undertaken in the design and production of the key components of the JUNO detector. Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution, extending beyond the statistical fluctuations of the detected number of photons, such as the properties of liquid scintillator, performance of photomultiplier tubes, and the energy reconstruction algorithm. To account for these effects, a full JUNO simulation and reconstruction approach is employed. This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution. The study reveals an energy resolution of 2.95% at 1 MeV. Furthermore, the study assesses the contribution of major effects to the overall energy resolution budget. This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data taking. Moreover, it provides a guideline in comprehending the energy resolution characteristics of liquid scintillator-based detectors

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^