基于迁移学习方法的山东冷云冰晶特征分布研究

为分析冷云中冰晶的分布特征,揭示冰晶增长演变机制,根据冰晶形状和尺度特征分为8类并进行标注,同时标注1类隔断栏进行数据质量控制,将9类标签图像整合并建立图像集,利用迁移学习VGGNet16方法进行识别训练,经训练模型分类准确率达98%。将模型应用到秋季冷云冰晶特征研究中,选取3次积层混合云和3次层状云降水过程,分析冰晶形状在不同温度区间的占比及冰晶谱变化特征,结果表明,温度通过影响冰晶基面与棱面的比值来决定冰晶初始形状分布,相同温度区间积层混合云内球状冰晶和线型冰晶占比高于层状云,低于-12℃后各类冰晶占比相对固定;积层混合云内线型冰晶直径集中在300~800 μm,冰晶谱呈多峰分布,聚合体直径大于600 μm,冰晶谱首尾两端浓度相当,球状冰晶直径集中在120～300 μm,冰晶谱呈单调下降趋势。     

Simultaneous quantification of greenhouse gas and nitric oxide emissions from subtropical conventional vegetable systems: a 2-site field case study in Sichuan Basin

Quantification of greenhouse gases[nitrous oxide(N₂O)and methane(CH₄)]and nitric oxide(NO)emissions from subtropical conventional vegetable systems through multi-site field measurements are needed to obtain accurate regional and global estimates.N2 O,NO and CH4 emissions from subtropical conventional vegetable systems were simultaneously measured at two different sites with hilly topography in the Sichuan basin,southwest China by using the static chamber gas chromatography technique.Results showed that annual soil N₂O and NO fluxes for the treatment receiving N fertilizer ranged from 6.34-7.71 kg N ha^-1 yr^-1 and 0.69-0.85 kg N ha^-1 yr^-1,respectively,while decreased soil CH4 uptakes by 26.4%as compared with no N fertilizer addition across our two sites of experiment.Overall,the average direct N2 O and NO emission factor(EFd)were 0.71%and 0.12%,respectively,which were both lower than the available EFd for subtropical conventional vegetable systems.This finding indicates that current regional and global estimates of N₂O and NO emissions from vegetable fields are likely overestimated.Background N₂O emissions(3.42-3.62 kg N ha^-1 yr^-1)from the subtropical conventional vegetable systems were relatively high as compared with available field measurements worldwide,suggesting that background N₂O emissions cannot be ignored for regional estimate of N₂O emissions in subtropical region.Nevertheless,the significantly intra-and inter-annual variations in N₂O,CH₄ and NO emissions were also observed in the present study,which could be explained by temporal variations of environmental variables(i.e.soil temperature and moisture).The differences in N₂O and NO EFd and CH₄emissions between various vegetable systems in particular under subtropical conditions should be taken into account when compiling regional or global inventories and proposing mitigation practices.     

下扬子区二叠系烃源岩评价与生源环境

基于下扬子区海域-陆域钻井岩心和露头岩样, 通过有机岩石学和有机地球化学方法, 应用有效指标参数, 从不同维度综合分析下扬子区上二叠统大隆组、龙潭组和下二叠统孤峰组、栖霞组4套烃源岩在纵向及平面上的有机地球化学特征、生烃潜力和生源环境。根据测试数据及前人研究资料, 栖霞组和大隆组烃源岩的有机质丰度为中等-好级别, 龙潭组烃源岩的有机质丰度为一般-中等级别, 孤峰组烃源岩有机质丰度达到很好级别。下二叠统烃源岩有机质丰度在平面展布上表现出海域优于陆域的特点, 上二叠统则反之。根据干酪根碳同位素特征, 栖霞组烃源岩有机质类型最好, 为Ⅰ~Ⅱ型; 其他3套烃源岩均为Ⅱ~Ⅲ型母质类型。4套烃源岩成熟度参数镜质体反射率主频分布范围为1.3%~2.0%, 均达到高热演化阶段, 在平面展布上表现出明显的非均一性。二叠系4套烃源岩生物来源以低等水生生物为主, 有机质均在贫氧的弱还原-弱氧化条件下保存, 其中大隆组沉积的水体动荡频繁和生物变化较明显。综合认为, 下扬子区二叠系烃源岩有机质丰度高, 类型较好, 具有形成大型油气田的良好物质基础, 尤其是以往被忽略的孤峰组烃源岩评价等级被提高, 是一套潜在的优质烃源岩, 其对该区进一步的油气勘探具有重要的指导意义。     

干湿循环下原状黄土抗压强度试验研究

黄土是干旱、半干旱条件下形成的,具有特殊结构的土,季节性的降雨和蒸发作用必将引起其力学性质和结构改变,从而造成其强度降低和变形增大的问题。通过单轴抗压强度试验探讨了黄土抗压强度与含水率、干湿循环次数的变化规律,借助SEM图像定性和定量分析了其强度变化的微观机制。试验结果表明：黄土单轴抗压强度随含水率的减小表现为非线性的增大;随干湿循环次数的增加而减小,经历多次干湿循环后趋于稳定;含水率增大和干湿循环次数的增加不仅仅会使得粗颗粒的接触方式改变与胶体物质和腐殖质数量减少,还会使得土体孔隙直径增大,大、中孔隙所占百分比之和明显增多,进而从微观结构阐述了土体宏观强度的变化规律。     

暴雨对四川三台县中新中学滑坡稳定性的影响

在平推式滑坡的稳定性分析中,暴雨是诱发滑坡失稳的重要因素。利用平滑式滑坡的力学模型,采用天然工况和暴雨工况对三台县中新中学滑坡进行了稳定性计算,结果表明暴雨产生的后缘裂隙静水压力是中新中学滑坡可能失稳的最主要因素。     

Data processing and initial results from the CE-3 Extreme Ultraviolet Camera

The Extreme Ultraviolet Camera(EUVC) onboard the Chang'e-3(CE-3)lander is used to observe the structure and dynamics of Earth's plasmasphere from the Moon. By detecting the resonance line emission of helium ions(He+) at 30.4 nm, the EUVC images the entire plasmasphere with a time resolution of 10 min and a spatial resolution of about 0.1 Earth radius(RE) in a single frame. We first present details about the data processing from EUVC and the data acquisition in the commissioning phase, and then report some initial results, which reflect the basic features of the plasmasphere well. The photon count and emission intensity of EUVC are consistent with previous observations and models, which indicate that the EUVC works normally and can provide high quality data for future studies.     

Combination Scattering by Anisotropic Langmuir Turbulence with Application to Solar Radar Experiments

We develop a theory for radar signal scattering by anisotropic Langmuir turbulence in the solar corona due to a t+l ⇄ t process. Langmuir turbulence is assumed to be generated within a cone by a narrow type III burst electron beam. Using wave-kinetic theory we obtain expressions for the frequency shift, scattering cross-section of the turbulence, coefficient of absorption (due to scattering) and optical depth. On the basis of those expressions we give some estimates for an echo spectrum. We show that the minimum radar echo frequency shift is determined by the minimal phase velocity of the Langmuir waves, the maximum shift is determined by the electron beam velocity, but in any case it can not exceed −wt/2 (decay) and wt (coalescence), where wt is the frequency of a radar signal. The angular characteristics of the scattered signal differ dramatically for the cases of coalescence and decay. The signal is scattered into a narrow cone high above the specular reflection point (wp ≪ wt), but in the vicinity of wp ∼ wt/2 the red-shifted echo is scattered isotropically, while the blue-shifted echo is scattered into a even narrower cone. We show that absorption (due to scattering) increases with increasing radar frequency. The dependence of the absorption on the local plasma frequency is strongly determined by the Langmuir turbulence spectrum. Our theory shows that the role of the nonlinear scattering process t+l ⇄ t is essential and that such process can be used for radar studies of the spectral energy density of anisotropic Langmuir turbulence.     

A Method to Determine the Solar Synodic Rotation Rate and the Height of Tracers

The dependence of the measured apparent synodic solar rotation rate on the height of the chosen tracer is studied. A significant error occurs if the rotation rate is determined by tracing the apparent position of an object above the photospheric level projected on the solar disc. The centre-to-limb variation of this error can be used to determine simultaneously the height of the object and the true synodic rotation rate. The apparent (projected) heliographic coordinates are presented as a function of the height of the traced object and the coordinates of its footpoint. The relations obtained provide an explicit expression for the apparent rotation rate as a function of the observed heliographic coordinates of the tracer, enabling an analytic least-squares fit expression to determine simultaneously the real synodic rotation rate and the height of the tracer.     

辽河三角洲滨海湿地水域初级生产力研究进展

滨海湿地位于海洋与陆地生态系统的交错过渡带,具有极高的生产力和光合固碳效率,是海岸带蓝色碳汇的重要组成部分。滨海湿地生产力不仅由芦苇、翅碱蓬、红树林等陆上植被提供,水体中浮游植物的光合固碳也是提供初级生产力的重要途径。以往较多的调查和研究集中在陆上植被,而对于滨海湿地水域浮游植物和底栖微藻的报道较少。近年来随着各国政府和学者对二氧化碳排放和气候变化的关注,滨海湿地多圈层生态系统的碳循环和碳汇过程成为研究热点,而湿地水域生产力和光合固碳过程作为多圈层碳循环中重要的一个环节亦应受到足够的重视。以中国北方典型的盐沼湿地区域——辽河三角洲滨海湿地为案例,对湿地水域生产力研究进展进行综述,并对其影响因素进行讨论,以期为国家碳循环与碳中和目标调查提供参考资料。     

滑坡灾害环境与山区建设的和谐

滑坡是浙江省沿海及丘陵山区频发的地质灾害之一,常堵塞交通、农田毁损、民房倒塌、使山区人民生活环境严重恶化。分析滑坡灾害机理,提早预警预报,是合理规划山区民居建设、治理地质灾害、建立民居与生态环境合谐的的关系,是各级政府、地质工程界、建设部门和环境监理部门的重要社会责任和理论研究范围。