不同运动模式的悬臂式挡墙地震永久位移算法EI北大核心CSCD

为了有效确定支挡边坡的悬臂式挡墙的地震永久位移,考虑悬臂墙踵板上方局部填土可能存在的不同滑裂特征,基于拟静力法、塑性极限分析上限定理与Newmark滑块法,针对地震条件下可能发生的墙-坡整体对数螺旋面转动、墙-局部填土体系水平滑动及绕墙趾转动3种运动模式,根据较为严格的力学定义分别推导了墙体地震永久位移计算公式。实例分析表明,前两种运动模式所得的地震永久位移相近,均远大于后一种模式,在工程设计中属于位移控制模式。与既有的经验公式法对比表明,文中方法与其误差在30%以内,且比概率置信水平取0.7的Ambraseys-Menu方法小7%。对于墙-坡系统整体旋转滑动模式,在水平地震影响系数一定的情况下,10个主要参数敏感性正交分析结果表明,其对水平屈服加速度影响的敏感性大小排序为:填土黏聚力、墙高、填土内摩擦角、墙体重度、立臂顶宽、填土重度、趾板长度、竖向地震影响系数、底板厚度和踵板长度。     

基于ROC曲线的永久散射体识别最佳阈值定量筛选

永久散射体识别是用PS-InSAR方法获取地面沉降数据的关键环节之一,其最佳阈值的设定直接影响PS点的精度和密度。本文基于大数据统计的分析方法——ROC曲线法定量分析和确定PS点识别的最佳阈值。选择3种典型的PS识别方法,绘制每种方法在不同阈值条件下的ROC曲线图,当ROC曲线下面积越大,方法越优。依据最佳阈值位于ROC曲线左上部位的特征,采用敏感度与特异度之和（Se+Sp）最大的方法可定量判定出最佳阈值的取值。在最佳阈值条件下,识别的PS点具有正选率足够高、误选率足够小,PS点的密度足够大的特性。为进一步验证该方法的可行性,本文以北京龙潭公园地区为PS识别的实验区,用振幅离差指数法、相关系数法,以及两种阈值相结合的双阈值法3种方法进行实验识别PS点,并根据ROC曲线判得3种方法的最佳阈值。研究结果发现：（1）振幅离差T_D识别PS点的最佳阈值为0.45;相干系数Tγ识别PS点的最佳阈值为0.45;振幅离差T_D、相干系数Tγ双重阈值识别PS点的最佳阈值（T_D,Tγ）为（0.50,0.50）。（2）用振幅离差T_D和相干系数Tγ双阈值法识别PS点,得到的ROC曲线下面积AUC=0.762,高于单阈值法,表明双重阈值法识别PS点优于单一阈值的PS点识别方法。研究表明ROC曲线可定量化确定PS点的最佳阈值,而且该方法可进一步推广于GIS空间分析、遥感解译过程中阈值的定量化筛选。     

An influencing mechanism for ecological asset gains and losses and its optimization and promotion pathways in China

Journal of Geographical Sciences - Accounting for the gains and losses of ecological assets holds scientific significance in sustaining human well-being. Based on related research on ecological...     

基于改进PSInSAR技术的非城区地表形变监测

为解决经典PSInSAR技术在非城区因受永久散射体空间分布不足而导致地形形变监测误差较大的问题,提出基于分时散射体(partial time scatterer,PTS)提取的改进算法。首先基于改进的经验模态分解对影像进行边缘保持平滑滤波降噪,然后采用可信概率估计对PTS目标进行联合提取,最后通过参数差分估计分离PTS相位和计算形变速率,从而得到监测区的地表形变。实验结果表明,提取的PTS目标基本可保持传统PS点的空间分布特性和时序变化趋势,提高非城区目标点的空间分布密度,本文算法具有有效性。     

Persistent activity and violent strombolian eruptions at Vesuvius between 1631 and 1944

During the period 1631–1944, Vesuvius was in persistent activity with alternating mild strombolian explosions, quiet effusive eruptions, and violent strombolian eruptions. The major difference between the predominant style of activity and the violent strombolian stages is the effusion rate. The lava effusion rate during major eruptions was in the range 20–100 m³/s, higher than during mild activity and quiet effusion (0.1–1 m³/s). The products erupted during the mild activity and major paroxysms have different degree of crystallization. Highly porphyritic lava flows are slowly erupted during years-long period of mild activity. This activity is fed by a magma accumulating at shallow depth within the volcanic edifice. Conversely, during the major paroxysms, a fast lava flow precedes the eruption of a volatile-rich, crystal-poor magma. We show that the more energetic eruptions are fed by episodic, multiple arrival of discrete batches of magma rising faster and not degassing during the ascent. The rapidly ascending magma pushes up the liquid residing in the shallow reservoir and eventually reaches the surface with its full complement of volatiles, producing kilometer-high lava fountains. Rapid drainage of the shallow reservoir occasionally caused small caldera collapses. The major eruptions act to unplug the upper part of the feeding system, erupting the cooling and crystallizing magma. This pattern of activity lasted for 313 y, but with a progressive decrease in the number of more energetic eruptions. As a consequence, a cooling plug blocked the volcano until it eventually prevented the eruption of new magma. The yearly probability of having at least one violent strombolian eruption has decreased from 0.12 to 0.10 from 1944 to 2007, but episodic seismic crises since 1979 may be indicative of new episodic intrusions of magma batches.     

谈浅海油田固定平台应急电站设计

结合埕岛中心二号平台的设计实践,对浅海油田固定平台应急发电机组的选型、布置、辅助系统配置、供电范围等内容进行探讨     

Impact of farmer households’ livelihood assets on their options of economic compensation patterns for cultivated land protection简

With rapid urbanization and the socio-economic transformation, cultivated land protection has gradually become a major concern in China. The economic compensation plays a crucial role in promoting cultivated land protection and improving the utilization ratio of cultivated land. Farmer household＇s satisfaction has a great influence on the effectiveness of compensation. Therefore, households＇ willingness to select the economic compensation pattern for cultivated land protection has been considered and re-examined. By employing Participatory Rural Appraisal method （PRA）, 3 villages and 392 households were investigated and sampled in mesa and hilly areas of Chongqing. Then a quantitative analysis framework of household livelihood hexagon has been developed to quantify the livelihood assets of differ- ent farmer households. Finally, the Gray Relation Model and Probit Regression Model have been employed to explore the coupling relationship between the household livelihood assets and their compensation pattern options. The results show that there are both qualitative and spatial heterogeneity in household livelihood assets. We found that the inequality of livelihood assets is evident for five household types. There is a spatial trend that the higher the eleva- tion, the less livelihood assets are. In addition, their options of economic compensation pat- tern vary from Chengdu Pattern to Foshan Pattern due to their difference in livelihood assets and difference in location. In detail, there is a coupling relationship between household live- lihood assets and their compensation pattern; negative correlation is observed between natural assets value and household pattern options, while the other livelihood assets have positive impacts on compensation pattern in varying degrees, which from the top are psy- chological assets, human assets, physical assets, financial assets, and social assets respec- tively. A conceptual compensation pattern system has been designed to meet the demands for farmer households mainly according to their shortage in livelihood assets. In addition, compensation method, compensation standard, the basis of compensation and the source of compensation funds have been proposed accordingly.     

徐州城市地质调查在城市“三线”划定中的应用

随着人口和经济活动的进一步聚集,生产、生活、生态空间的矛盾日益突出,"三线"(即永久基本农田保护红线、生态保护红线、城市开发边界线)的划定在我国经济结构实现转型发展关键期,对优化城乡空间结构、确保国家粮食安全、严守生态底线等至关重要。以徐州城市地质调查成果为基础,基于地质条件对城市发展的制约和影响,提出城市"三线"的调整建议,不仅可为构筑生产空间集约、生活空间宜居、生态空间优美的城市空间格局提供地质依据,亦可为城市地质调查工作提供工作转型和战略调整方向。     

考虑动态临界加速度的地震边坡永久位移预测模型研究

在区域边坡地震危险性评价中主要采用永久位移预测模型进行地震边坡永久位移计算.永久位移预测模型以Newmark滑块理论为基础,通过大量实测地震时程记录统计拟合得出.针对Newmark理论中滑动面抗剪强度参数保持不变和已有位移预测模型的计算位移小于实测位移的问题,利用动态临界加速度理论,分别构建含有峰值加速度和阿里亚斯强度...     

无居民海岛资源资产核算与账户体系构建研究

无居民海岛资源是海洋资源资产的重要组成部分，开展无居民海岛资源资产的核算方法及账户体系构建技术研究对于统筹推进自然资源资产产权制度改革具有重要意义。本文以环境经济综合核算（SEEA-2012）为编制依据，探索无居民海岛资源资产核算方法与账户体系构建路径。首先，参照“实物统计-价格估算-价值核算”的逻辑思路设计核算流程；其次，为反映无居民海岛资源所有权和使用权现状，从“总量所有”和“开发利用”两个方面来研究实物与经济价值核算方法；再次，以收益还原法为基础，构建出无居民海岛资源资产权益价格和开发收益价格评估方法；最后，设计出无居民海岛资源资产实物与价值核算表式结构与账户体系。