A New Nonparametric Discriminant Analysis Algorithm Accounting for Bounded Data Errors

In a statistical pattern recognition context, discriminant analysis is designed to classify, when possible, objects into predefined categories. Because this method requires precise input data, uncertainties cannot be propagated in the classifying process. In real case studies, this could lead to drastic misinterpretations of objects. A new nonparametric algorithm based on interval arithmetic has thus been developed to propagate interval-form data. They consist in calculating interval conditional probability density functions and interval posterior probabilities. Objects are eventually assigned to a subset of classes, consistent with the data and their uncertainties. The classifying model is thus less precise, but more realistic than the standard one, which we prove on a real case study.     

Logs Fluid Typing Methods and Adaptive Analysis of Tight Sandstone Reservoir of Yingcheng Formation in Lishu Fault

Tight clastic reservoirs are characterized with low porosity and low permeability, which reduce contributions of reservoir fluids to geophysical logging responses, and it is more difficult to identify fluids of the reservoir. Therefore, it is necessary to study log interpretation and comprehensive evaluation methods for such clastic reservoirs. This study focused on geological characteristics of tight clastic reservoir of Yingcheng formation in Lishu Fault. Based on logs sensitivity to fluids, some fluid typing methods were discussed in detail, which included log curve overlap method, acoustic time overlapping method from density and neutron logs, porosity difference and ratio method, porosity-resistivity crossplot, normal distribution method, and other methods, and some effective fluid evaluation method were established and optimized. These above-mentioned methods were verified, which could achieve layer qualitative identification of tight sandstone in the study area. By contrast, two logs overlapping methods, porosity difference and ratio method, resistivity-porosity crossplot are more suitable for natural gas reservoirs, while porosity difference and ratio method, porosity-resistivity chart, normal distribution method are more suitable for oil and water reservoirs. The case study suggests that these methods be combined to archive more correct log interpretation in the study area, which provides important decision-making reference for oilfield exploration and development.     

自动建模客观分型方法在非汛期人工增雨中的应用

根据安徽省人工影响天气业务系统需要,利用NCEP 500 hPa高度场和风场格点资料及安徽省81站10年非汛期逐日降水资料,在客观分析天气形势基础上,结合预报员实践经验给出的不同系统影响安徽省时的关键区,计算机自动建模,形成逐日天气型日历,实现环流分型客观化。此方法识别条件实用,模型物理意义明确,自动化程度高,自动生成的逐日天气型日历,为安徽省非汛期人工增雨作业指挥系统提供了很好的天气预报参考依据。     

Meteorology in Canada: A reaction to the rose report

The methods used in an earlier study focusing on the province of Ontario, Canada, were adapted for this current study to expand the study area over eastern Canada where the infrastructure is at risk of being impacted by freezing rain. To estimate possible impacts of climate change on future freezing rain events, a three-step process was used in the study: (1) statistical downscaling, (2) synoptic weather typing, and (3) future projections. A regression-based downscaling approach, constructed using different regression methods for different meteorological variables, was used to downscale the outputs of eight general circulation models to each of 42 hourly observing stations over eastern Canada. Using synoptic weather typing (principal components analysis, a clustering procedure, discriminant function analysis), the freezing rain-related weather types under historical climate (1958–2007) and future downscaled climate conditions (2016–2035, 2046–2065, 2081–2100) were identified for all selected stations. The potential changes in the frequency of future daily freezing rain events can be projected quantitatively by comparing future and historical frequencies of freezing rain-related weather types.

The modelled results show that eastern Canada could experience more freezing rain events late this century during the coldest months (i.e., December to February) than the averaged historical conditions. Conversely, during the warmest months of the study season (i.e., November and April in the southern regions, October in the northern regions), eastern Canada could experience less freezing rain events late this century. The increase in the number of daily freezing rain events in the future for the coldest months is projected to be progressively greater from south to north or from southwest to northeast across eastern Canada. The relative decrease in magnitude of future daily freezing rain events in the warmest months is projected to be much less than the relative increase in magnitude in the coldest months.     

基于模糊聚类分型的数值产品暴雨预报释用方法

本文阐述了一种基于数值产品的预报信息场的暴雨预报释用方法,提出了对暴雨历史样本形势场使用模糊聚类的客观分型技术,用条件概率让小概率事件成为相对的大概率,更有利于暴雨指标的提炼;该释用方法包含的信息量全面,以历史暴雨样本同期的包含大气三维空间压、温、湿、风及其释演的物理量,构建出25个数值产品参数指标作为鉴别暴雨的基础,同时也勾划出各暴雨型发生期大气高温、高湿、对流不稳定等机理结构特征,且均有具体物理量数据表述.预报方法的研究过程中探索了某些物理量场预报暴雨落区的规律;建立了暴雨预报工具,充分利用了现有业务中的质量较好的预报产品设立预报工具的起报条件,减少了暴雨空报率.     

汾渭平原PM2.5-O3复合污染特征及气象成因分析

PM_2.5和O₃已经成为汾渭平原城市最主要的污染物,两者之间相互影响,在暖季经常同时出现构成污染,其污染程度与气象条件密切相关。利用2015—2021年汾渭平原12个城市逐日PM_2.5和O₃浓度、地面气象观测数据以及ERA5高空再分析数据等资料,分析了汾渭平原PM_2.5和O₃的时空变化特征以及复合污染发生时PM_2.5和O₃的关系,并研究了局地气象条件和天气形势对复合污染的影响。结果显示,该地区年均PM_2.5和日最大8小时O₃浓度分别在2017年和2018年开始持续下降,复合污染日数也在2019年后开始持续下降;复合污染主要发生在3—9月,在汾渭平原东部城市出现次数较多,多出现在高温、低湿的环境下;最后利用T-PCA算法(正交主成分分析)将复合污染的天气环流形势分为4种类型,主要呈现出以高空西北气流或偏西气流、低层为暖区偏南风或微风为主的天气特征。研究结果对汾渭平原的大气...     

陕西关中重污染天气低空流场的分型研究

利用陕西关中区域内五市(西安、咸阳、渭南、铜川、宝鸡)有PM2.5监测数据以来的2014—2019年各市污染指数(AQI)筛选代表年,定义关中区域污染和区域重污染天气过程,结合陕西WRF(Weather research&forecasting model)模拟数据,对影响关中区域的流场分型,并重点研究了各流场分型与P...     

SCCmec 相关的 psm-mec 在血液来源人葡萄球菌中的基因定位

目的：了解 SCCmec 相关的 psm-mec 基因在血液来源人葡萄球菌中的基因定位特征,为深入研究 psm-mec 基因在人葡萄球菌中的功能奠定基础。方法收集临床血培养分离的人葡萄球菌25株,通过 PCR 扩增 mecA 基因和 psm-mec 基因,多重 PCR 对耐甲氧西林人葡萄球菌 SCCmec 分型,PCR 扩增 mecR1／psm-mec 基因与 psm-mec／xylR 基因间隔序列及 fudoh 基因,探究 psm-mec 基因在 SCCmec 上的定位特点。结果 PCR 检测显示,21株为耐甲氧西林人葡萄球菌,psm-mec 基因的检出率为47．6％,4株为甲氧西林敏感人葡萄球菌,未检出 psm-mec 基因。多重 PCR 结果显示,10株 psm-mec 基因阳性菌株中,2株属典型 SCCmec Ⅲ型,5株属类 SCCmec Ⅲ型,3株属 SCCmec 新型别。基因间隔序列和 fudoh 基因检测显示,10株 psm-mec 基因阳性人葡萄球菌中,mecR1／psm-mec 基因和 psm-mec／xylR 基因及 fudoh 基因均阳性。结论 SCCmec 相关的 psm-mec 基因广泛存在于血液来源的人葡萄球菌中,主要分布在典型 SCCmec Ⅲ型、类 SCCmecⅢ型和 SCCmec 新型别上,定位于 mecR1基因与 xylR 基因之间。     

Sapphire within zircon-rich gem deposits,Bo Loei,Ratanakiri Province,Cambodia: trace elements,inclusions, U–Pb dating and genesis

Subordinate sapphire accompanies prevalent zircon megacrysts in the Bo Loei basaltic gem field, Ratanakiri Province, Cambodia. These deposits are important for heat-treated gem zircon. Dark blue sapphire, with rare blue-green, orange-brown and yellow stones, up to a few cm in size, include hexagonal-shaped and growth-zoned crystals. Analyses of the sapphires (electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry) showed Fe as the main chromophore (0.6–2.7 wt%), with minor Ti (<0.7 wt%). Sapphire cores show enrichment in Fe relative to rims and some include exotic heavy elements (Nb up to 56, Ta up to 144, Sn up to 5 ppm). The sapphires show high Ga values (271–724 ppm) and Ga/Mg ratios (4.8–77.0) suggesting magmatic associations. Two sapphires with syngenetic inclusions (zircon, Nb-rich rutile) gave U–Pb (Th-disequilibrium corrected) ages at ca 0.93 ± 0.1 Ma. The Bo Loei sapphires show higher Fe and Ga than other magmatic sapphire suites elsewhere in Cambodia (Pailin), Laos (Ban Huai Sai, Ban Sam Sai), South Vietnam (Dak Nong, Dak Lac) and SE Thailand (Chanthaburi-Trat). This suggests potential for geographic typing of sapphire suites between these different fields.     

(T2,D)二维核磁共振测井混合反演方法与参数影响分析

一维核磁共振(1D NMR)测井技术在流体识别中具有一定的局限性.二维核磁共振(2D NMR)测井能同时测量到多孔介质中横向弛豫时间(T₂)和扩散系数(D)等信息,利用这两个参数区分流体性质,较一维核磁共振测井技术具有明显的优越性.针对梯度场下的2D NMR测井弛豫机理和数学模型,提出了适用于求解大型稀疏矩阵方程的反演方法-基于非负最小二乘法(LSQR)和截断奇异值分解(TSVD)法的混合算法.为验证方法的有效性,先根据多回波观测模式合成回波串数据,然后再用混合反演算法进行反演,反演得到横向弛豫时间(T₂)和扩散系数(D),并构建T₂-D二维谱图.结果对比表明,该混合反演算法得到的T₂-D二维谱与流体模型一致性好,计算精度均比单一反演方法有较大改善,表明该混合反演方法可用于油气储集层2D NMR测井的反演和流体识别.此外,分别对油水同层和气水同层模型进行了正演模拟和反演实验, 系统考察了不同磁场梯度、不同回波间隔组合对反演效果的影响,为2D NMR参数设计提供依据.