强台风海葵登陆前后强度变化的观测分析

1211号台风海葵强度强,在近海及登陆前后中、日、美三个国家的业务定强差别较大。云图分析“海葵”强度强,近海后云顶亮温长时间在-70℃以下。雷达资料表明“海葵”登陆前后,结构对称,眼区清晰,范围增大。登陆点附近沿海测站出现了长时间的强大风,过程13级及以上阵风共持续了26 h,东矶、大陈、石浦最大风速的极大值分别是：46.9、39.4和36.8 m·s-1。风场垂直分布差别500 m以内普遍在7~8 m·s-1。这些陆基观测资料表明“海葵”可能达到了强台风标准,中央气象台定强是合理的。近海或登陆台风强度的确定在使用Dvorak技术的基础上,还应更多地参考陆基探测资料。     

区域旅游目的地竞争优势的空间聚类分析——以浙江省为例

基于两维图论聚类方法,将主成分分析与两维图论聚类分析有机结合,建立区域旅游目的地竞争优势综合评判模型.首先,建立区域旅游业竞争优势的评价指标体系;接着,利用主成分分析方法对区域旅游竞争优势进行综合评估,并将其应用于浙江省旅游竞争优势评价;最后,以各个旅游目的地的主成分因子为分类对象,采用两维图论聚类法,对各地的旅游竞争优势进行空间聚类分析.研究结果表明,主成分分析与两维图论聚类分析有机结合研究区域旅游目的地的竞争优势是可行的,两维图论聚类能较好地反映区域旅游竞争优势和空间相关性,其结果将有助于决策者制定区域旅游发展战略.     

中国区域多源土壤湿度数据的比较研究

利用中国区域1992~2010年的土壤湿度观测资料,对欧洲航天局(European Space Agency)的卫星遥感反演(以下简称ESA)和欧洲中期天气预报中心(European Centre of Medium-Range Weather Forecasts,ECMWF)的ERA-Interim(ECMWF Reanalysis-Interim,以下简称ERA)两套再分析土壤湿度数据在典型区域的可靠性进行了评估。结果表明:两种土壤湿度均能较好的描述观测区域的总体土壤干湿变化,但均值和趋势一致性存在时间和空间差异。ESA、ERA资料都能较好的描述中国区域春、夏、秋3个季节土壤湿度的干、湿分布格局。在干湿程度上,ESA在北方地区较观测偏干,在江淮和西南较观测偏湿;ERA在北方和西南地区较观测偏湿,在江淮较观测偏干;在江淮、华北部分区域,ERA与观测数据的相关性要高于ESA。ESA、ERA与观测在秋季时相关性最好(大部分站点大于0.7);在全国大部分区域,ESA偏差要小于ERA且在大部分地区都表现出与观测一致的变化趋势。在空间上,ERA在东北、华北、西南变干的范围明显大于观测;然而,ERA能更好的体现观测土壤湿度的年际变化。相对于西部地区,东部地区ERA与观测的一致性最好,而ESA在受降水、植被、地形等因素影响较小的时段或区域与观测的一致性更好,对秋季土壤湿度的描述比春、夏季更准确。     

Rapid estimation of maximum and minimum void ratios of granular soils

Maximum and minimum void ratios (e_max and e_min) of granular soils are commonly used as indicators of many engineering properties. However, few methods, apart from laboratory tests, are available to provide a rapid estimation of both e_max and e_min. In this study, we present a theoretical model to map the densest and the loosest packing configurations of granular soils onto the void space. A corresponding numerical procedure that can predict both e_max and e_min of granular soils with arbitrary grain size distributions is proposed. The capacity of the proposed method is evaluated by predicting the maximum and minimum void ratios of medium to fine mixed graded sands with different contents of fines. The influence of the grain size distribution, characterized quantitatively by uniformity parameter and the fractal dimension, on e_max and e_min is discussed using the proposed method. Moreover, application of this method in understanding the controlling mechanism for the void ratio change during grain crushing is presented.

     

Conceptual Framework for Key Element Identification in Important Agricultural Heritage Systems (IAHS): Case of Honghe Hani Rice Terraces System in China

With the continuous emergence of global development problems, the dynamic conservation and sustainable development of Important Agricultural Heritage Systems (IAHS) have been assigned greater importance. However, due to the complex structure, multi-component, dynamic, and open characteristics of IAHS, there are neglected problems which need to be solved in conservation practice, such as component element ambiguity, obscurity of the conservation redline, etc. This study defined the concept of key elements (KE) of IAHS, put forward a conceptual framework of KE identification, conducted empirical research by taking Honghe County of Honghe Hani Rice Terraces System (HHRTS) as an example and analyzed the level of recognition motivations for different stakeholder groups. The following conclusions were drawn: 1) The KE of HHRTS are grain crops, rice species biodiversity, terrace construction and maintenance technique, Hani traditional festivals, Hani traditional foods, and virgin forest; 2) The reasons behind the KE priorities of farmers, businessmen and tourists were at the micro level, the reasons of officers were at the middle level and the reasons of researchers were at the macro level. The empirical study conducted in HHRTS showed that the proposed conceptual framework could identify KE of IAHS effectively, and provided a theoretical perspective for the structuring of and essential need for IAHS research. Moreover, the KE recognition levels of different stakeholder groups reflected their potential action strategies. We should focus on the coherence of policies and measures in both the microscale and macroscale to balance the diversified demands of stakeholders, and to stimulate their enthusiasm for participation in the conservation in order to improve the management level of IAHS sites.     

剪切带中矿化与非矿化地段流体——岩石相互作用差异性研究

以河南西峡石板沟金矿为例,选择了一条控矿剪切带,对其中成矿地段的近矿蚀变岩和非成矿地段糜棱岩进行了系统的采样,探讨了二者在流体-岩石反应及岩石质量平衡之间的差异性。研究表明,剪切带中矿化地段蚀变岩其岩石体积总是扩容的,非矿化地段糜棱岩在变形过程中体积是损失的。矿化地段蚀变岩活性元素(K、Na、Si)总体呈被带入趋势,非矿化地段糜棱岩活性元素总体呈迁出趋势,糜棱岩的流体岩石率(N_u为93.68—468.40)远大于蚀变岩的流体岩石率(Nc_(Ⅳ)^s为36.11-216.67),剪切带中常量元素与微量元素富集与损失是渗透性流体带入、带出,岩石的体积损失与扩容综合作用的结果。     

凸轮型冲击旋压钻头成孔机理研究

挤密钻头是潜孔锤冲击挤密钻进技术的关键所在,其结构形式直接影响着钻进效率、成孔质量和应用效果。应用非线性有限元理论,对动载荷作用下土体的弹塑性和压缩性的变化规律进行了分析。研究发现,常规钻头在冲击挤密钻进过程中产生的桩效应是导致钻进效率降低的主要原因。为了克服桩效应的影响,利用ANSYS/LSDYNA软件对阶梯式钻头和凸轮旋压钻头的钻进过程进行数值模拟分析,并通过实钻试验进行验证。数值模拟分析和试验结果均表明：凸轮旋压钻头能够有效避免钻进过程中土体回弹问题,降低桩效应对钻进效率的影响。试验结果与模拟结果相吻合,表明数值模拟的结果相对可靠。     

UAV survey and numerical modeling of loess landslides: an example from Zaoling,southern Shanxi Province,China

Natural Hazards - This work attempted to reveal the geometric and kinematic characteristics of a loess landslide that occurred at Zaoling, southern Shanxi Province, China, on March 15, 2019. Based...     

京津冀平原区地下水水位变化主导因素的定量识别研究

自20世纪60年代以来,京津冀平原区地下水水位持续下降,制约着京津冀一体化的发展。为了识别地下水水位下降的主导因素,定量表征了影响水位动态的气候条件和人类活动的多项指标(包括降水、气温、水面蒸发、工业总产值、粮食产量、人口数量、地表径流量),并采用非参数统计检验方法(M-K法)阐明了近50年来各项指标的演化规律;在掌握研究区自然社会指标及地下水水位的动态规律的基础上,联合运用灰色系统理论和主成分回归分析方法,定量识别了地下水水位变化的主导因素。结果表明,近50年,研究区降水呈现下降趋势,气温呈现显著的上升趋势,水面蒸发呈现增加趋势,工业总产值、粮食产量、人口数量呈现增加趋势,由于山前水库修建引起的地表径流量呈现减小趋势;上述指标变化影响了研究区的地下水水位动态,其中逐渐加剧的人类活动(包括粮食产量、人口数量)构成了研究区地下水水位持续下降的最主要驱动力,对地下水水位下降的贡献度达到60.6%,气候条件对地下水水位下降的影响作用次之,其贡献度为39.4%。     

Hazard Assessment of Co-seismic Landslides Based on Information Value Method: A Case in 2018 MW6.6 Hokkaido Earthquake, Japan

An M_W6.6 earthquake occurred in eastern Hokkaido, Japan on September 6^th, 2018. Based on the pre-earthquake image from Google Earth and the post-earthquake image from high resolution (3 m) planet satellite, we manually interpret 9 293 coseismic landslides and select 7 influencing factors of seismic landslide, such as elevation, slope, slope direction, road distance, flow distance, peak ground acceleration (PGA) and lithology. Then, 9 293 landslide points are randomly divided into training samples and validation samples with a proportion of 7:3. In detail, the training sample has 6 505 landslide points and the validation sample has 2 788 landslide points. The hazard risk assessment of seismic landslide is conducted by using the information value method and the study area is further divided into five risk grades, including very low risk area, low risk area, moderate risk area high risk area and very high risk area. The results show that there are 7 576 landslides in high risk area and very high risk area, accounting for 81.52% of the total landslide number, and the landslide area is 22.93 km², accounting for 74.35% of the total area. The hazard zoning is in high accordance with the actual situation. The evaluation results are tested by using the curve of cumulative percentage of hazardous area and cumulative percentage of landslides number. The results show that the success rate of the information value method is 78.50% and the prediction rate is 78.43%. The evaluation results are satisfactory, indicating that the hazard risk assessment results based on information value method may provide scientific reference for landslide hazard risk assessment as well as the disaster prevention and mitigation in the study area.