Korean Americans in Los Angeles: Decentralized Concentration and Socio‐spatial Disparity

This study analyses the socioeconomic and demographic make‐up of Koreans in Los Angeles metropolis, the largest hub of Koreans in the United States, to better understand the decentralized concentration of Koreans by addressing their within‐ and among‐group variations. By employing the rarely used measures of correspondence and typology analyses, we delineate the boundaries for Korean clusters using Getis and Ord G* local statistic, wherein each cluster's neighborhood and demographic characteristics are compared to gain nuanced insights of within‐group variations, and its evolution during 1970–2010. Cluster level analysis of Koreatown suggests that even though it was classified as a Korean cluster, Korean Americans were unevenly distributed across these clusters, with underrepresentation in white‐dominant neighborhoods, whereas much of their intraurban spaces were shared with Hispanics. All clusters except extended Koreatown exhibited Li's ethnoburb‐style spatial patterns. The Koreatown and suburban clusters were also distinct in terms of their demographic/ethnic, socioeconomic, educational, age/life cycle, and housing characteristics, suggesting socio‐spatial polarization. Our analysis, challenges the commonly perceived notion of Koreans being a homogenous group and Asians being model minorities. We illustrate significant within‐group differences among the Koreangelos. We, thus, propose innovative measures to analyze population groups to flesh out rich narratives of America's fast changing social geographies.     

工程随机地震动物理模型的参数统计与检验

利用PEER强震记录数据库,确定了一类实用的随机地震动模型的参数概率分布。依据GB50011-2010规定的场地类别,对4438条实测地震动记录进行分组。引用系统识别方法对不同场地上的地震动记录进行参数识别,据此结果,对工程地震动物理随机函数模型的基本参数进行了统计分析,给出了随机地震动模型参数的概率分布密度。对基本随机参数的概率空间进行剖分,结合波群叠加方法生成地震动时程,计算获得了随机地震动反应谱。通过比较随机反应谱和实测地震动反应谱的统计特征量,验证了地震动物理随机函数模型及基本随机参数统计结果的正确性。     

FAO's statistic data and sustainability of fisheries and aquaculture: Comments on Pauly and Zeller (2017)

In a recent commentary, Pauly and Zeller disagreed with the Food and Agriculture Organization's interpretation of its global capture fishery production records, arguing that trends were distorted by unreliable statistics in some countries. They criticized FAO for not having used their “catch reconstructions” in the 2016 State of the World Fisheries and Aquaculture (SOFIA) report and questioned the interpretation and significance of FAO's aquaculture production statistics. In this paper, we refute their claims and demonstrate that their critique is based on fundamental misunderstandings caused by mixing up statistical metrics and using simple normative explanations to interpret highly complex datasets. We explain how FAO maintains, curates and updates the only validated source of global fisheries landings, describe our capacity building projects and activities underpinning the annual updates for the over 231 different sources of fisheries data, and clarify such updates include dialogues with member countries to improve and revise present and historical records. FAO will continue to work closely with member states, IGOs, NGOs, academia and civil society, to further improve fishery and aquaculture databases, while calling on states to make renewed efforts to improve data quality. It also welcomes research efforts that contribute to the improvement of statistical data which are critical to the sustainable management of fisheries and aquaculture.     

辽宁省阜蒙县南部地区土地利用现状分析

以辽宁省阜新蒙古族自治县南部乡镇为例,按照土地合理利用与保护的基本原则和要求,利用土地利用现状数据、SRTM雷达地形数据、社会经济统计数据以及历史资料,借助地理信息系统软件ArcGIS,依据土地利用结构研究的基础理论和可持续发展的观点,采用土地利用数量结构分析数学模型的研究方法,对研究区域土地利用现状进行分析研究,为辽宁省西北部干旱和半干旱地区小区域土地现状管理、分析和可持续开发利用提供科学的依据.     

Searching for strange attractor in wastewater flow

 Chaos is a complex and irregular world in contrast with simple and regular natures of linear systems. Scientists and engineers have invoked low-dimensional chaos for understanding the nature of real systems. In this study, the complex behavior of a daily wastewater flow and evidence of deterministic nonlinear dynamics are investigated. The analysis involves both a metric approach of the correlation dimension and a topological technique called the close returns plot. The estimation procedure of delay time and delay time window is reviewed using a new technique called the C–C method for the state space reconstruction. And both parameters are used for estimating the correlation dimension. As a result, the daily wastewater flow shows no evidence of chaotic dynamics, which implies that stochastic models rather than deterministic chaos may be more appropriate for representing an investigated series.     

渤海海水pH时空分布特征与趋势分析

基于2011−2017年海水pH和环境参数数据,应用格网统计和时空矩阵方法,研究各环境单元内pH和环境因子同比变化及相关性,并对影响不同季节、区域和水体层次的相关因子作差异性分析,结果显示：(1) 2011−2017年间,渤海区域pH的空间分布整体相对稳定,各环境单元表层pH平均值为7.95～8.38,底层pH平均值为7.89～8.35,平均值绝对变化为1～1.5个标准差;(2)各环境单元pH时间序列趋于同步变化,由于空间分布不同,局部单元间存在差异,研究认为冬季表层pH低值和盐度高值空间分布特征一致;(3)渤海区域pH与叶绿素a浓度呈现显著正相关,表层pH季节性特征明显,且与叶绿素a时空分布特征一致,生物因素对近岸表层水体pH的调节起重要作用;(4) 8月间渤海底层出现pH局部低值的区域,分析发现这与水体层化形成低氧区域相一致,同时发现底层pH与溶解氧呈显著正相关;(5)利用格网化数据处理技术和时空矩阵分析方法,进一步显化了pH和环境因子特征信息,对气候变化下长时间尺度的分析研究提供了很好的技术支撑。     

Sensitivity of disease cluster detection to spatial scales: an analysis with the spatial scan statistic method

ABSTRACT

The spatial scan statistic method has been widely used for detecting disease clusters. Its results may be affected by scales, including the aggregation level of the input data and the population threshold used in the detection. Previous studies offered inconsistent findings, and few had considered both types of scales at the same time. Using 24 simulated datasets and two real disease datasets, we investigated the method’s sensitivity to the two types of scales. We aggregated the individual-level data into areal units of three levels, including county, town, and a 900 m grid. We detected clusters with three population thresholds, including 10%, 25%, and 50%. We used two measurements, distance between cluster centres and the Jaccard index, to quantify the consistency of clusters detected with different scale settings. We find: (1) the method is not greatly sensitive to the data aggregation level when the cluster is strong and in a place with high population density; (2) the method’s sensitivity to the population threshold is determined by the actual size of the true cluster; and (3) a regular grid with fine resolution is advantageous over the subjectively defined areal units. The process and findings may have broader meanings to similar spatial analyses.     

ECMWF集合预报统计量产品在重庆降水预报中的检验与分析

利用ECMWF集合预报降水资料和重庆市自动站降水资料,运用晴雨、TS评分、预报偏差等检验方法对重庆地区2014—2016年ECMWF集合预报降水产品在短期时效的预报性能进行检验分析。结果表明:最小值的晴雨预报准确率最高。对于TS评分检验,小雨量级可优先参考最小值、10%分位数和融合产品,中雨量级参考平均数和概率匹配平均,大雨和暴雨量级分别参考75%分位数和90%分位数。对于预报偏差检验,小雨量级可优先参考最小值、Mode,中雨量级参考融合产品、中位数,大雨量级参考控制预报、融合产品,暴雨量级参考90%分位数。对于百分位值预报产品和概率预报产品,小雨量级可参考5%～10%分位数和80%～90%概率预报产品,中雨量级可参考45%～55%分位数和40%概率预报产品,大雨量级可参考70%～80%分位数和20%概率预报产品,暴雨量级可参考90%～95%分位数和10%概率预报产品。     

京津冀地区冬小麦气候生产潜力的一种动态区划

以京津冀地区的冬小麦农业气候生产潜力为研究对象,根据统计检验聚类方法(CAST)与旋转主分量分析(RP-CA)相结合的气候分类区划新方法,对该区冬小麦气候生产潜力进行了区划试验,计算验证了理论与实际结果的一致性,从而进一步证明该方法的合理性及可靠性。同时也印证了CAST和RPCA用于气象场分类区划具有等价性和互补性的事实;此外,各分区具有不同的年际变化特征,也表明区划结果是合理的,从而较好地佐证了这一新的分区方法。     

辽河断陷西部凹陷油气成藏主控因素

辽河西部凹陷油气资源非常丰富,通过对己勘探发现的773个油气藏的地质特征参数统计认为,西部凹陷油气藏类型非常丰富,但主要以构造和岩性油气藏为主,且复合油气藏发育,统计表明,近90%的油气藏与断裂有关。油气藏类型受构造带控制作用明显,缓坡带最要以背斜、岩性构造油气藏为主,中央背斜带背斜断块油气藏较为发育,而陡坡带则多为岩性油气藏。沉积相带控油气作用明显,油气藏主要分布在扇三角洲、三角洲和浊积扇相。油气资源在空间上遵循“油气总量平衡模式”,无论在平面上还是层位上,油气资源互补特征性强。研究认为西部凹陷具有生烃洼陷、断裂、异常压力、沉积相带联合控藏的特点。首先沙三段、沙四段有效烃源岩大量发育,资源量极为丰富,为西部凹陷油气富集提供了物质保证,油气藏分布主要受生烃洼陷控制;各组段砂体叠合连片,平面展布连续,具较好的储集能力,也为油气的侧向运移提供的条件;另外东营末期因走滑引起的大量泄压断裂发育,为油气大规模远距离垂向运移提供了可能。