海底底质分类反向散射强度三维概率密度法

反向散射强度随入射角变化信息蕴含海底底质特性,是多波束海底底质分类的重要数据源。目前,多波束海底底质分类主要提取平均反向散射强度随入射角的变化信息或基于声呐图像,没有综合考虑两者的相关信息。本文综合考虑平均反向散射强度随入射角变化信息及其概率密度分布,绘制三维概率密度图,提出了基于反向散射强度三维概率密度图的海底底质分类方法。实例计算结果表明:该方法能直观表达多波束条带覆盖区内不同海底底质类型的数量,有效判断不同海底底质类型的边界,实现海底底质类型的快速识别。     

Seawall case studies and failure analysis of sloped concrete walls under static and dynamic loads

Concrete seawalls are structures in coastal facilities for shore and slope protections. Owing to several advantages of sloped or inclined walls such as minimum soil disturbance and less required earthworks, they can be considered as an appropriate alternative to vertical cantilever retaining walls. The combination of slab and strip semideep foundation instead of heel–toe slab foundations increases their capability for stability, erosion control, and storm wave energy dissipation. In this paper, three case studies from seawalls in which failure has occurred are presented and discussed. Technical performance of sloped walls against different internal and external instability factors is investigated, and comparisons are made between vertical and sloped (inclined) walls with respect to geotechnical and structural aspects through parametric study. Analysis indicates that the sloped retaining walls perform better from technical, practical, and economical standpoints. It was found that for identical static and dynamic loads, including earthquake and wave loads, inclined walls provide relatively higher safety factors against different criteria and exhibit more stable and practical performance compared with commonly used walls in practice. The case studies in this paper illustrate causes of failure in each case and gives suggestions for improving instability prevention of walls against static and dynamic loads.     

Rural Poverty Patterns and Influencing Factors in Yunnan Province,China: Based on County Level Dataset

The identification of poverty at the county level is the precondition for poverty alleviation by formulating accurate strategies that are targeted for a certain area. Yunnan Province has the largest number of poverty counties in China. The vast number of people living under the poverty-line, and the deep degree of poverty across a wide distribution range, pose major challenges. Based on the rural poverty incidence data, this paper describes the rural poverty patterns in Yunnan Province in 2010 and 2015, and then it explores the main factors which influence the incidence and changes in rural poverty at the county level in Yunnan Province using a stepwise regression analysis method. This study found that the rural poverty in counties of Yunnan Province was deeply affected by natural conditions and the geographical environment. In 2010 and 2015, the rural poverty situation in the middle region of Yunnan Province was relatively light, while it was more serious in the northwest, northeast and south regions. The pattern of county poverty is in good agreement with the topography and landforms of Yunnan Province and the poverty-stricken areas. There are strong correlations between the incidence of rural poverty in Yunnan Province with both the annual per capita net income of rural residents and the degree of agricultural mechanization. These factors are related to the living standards and agricultural production necessary for the peasantry to sustain their livelihood. The change in the incidence of rural poverty at the county level in Yunnan Province from 2010 to 2015 is significantly correlated with changes in the value-added of the primary industries and the degree of agricultural mechanization. These correlations indicate that the development of primary industry plays a key role in the process of lifting rural residents in Yunnan Province out of poverty so they can achieve prosperity. Therefore, improving the annual per capita net income of rural residents and the degree of agricultural mechanization for rural areas in Yunnan Province are still the main points for focused efforts. In the current phase of poverty alleviation, Yunnan Province should emphasize increasing rural residents' income and agricultural production and management in order to formulate effective policies and measures for poverty alleviation.     

倾向,倾角和倾伏向,倾伏角,侧伏向,侧伏角,侧余角的关系：以面理？…

研究了斜井素描过程中 ,面理在硐顶的迹线的描绘方法 ,对倾向、倾角和倾伏向、倾伏角、侧伏向、侧伏角、侧余角的关系作了较深入的研究。所阐述的方法 ,除了对斜井素描可以运用外 ,可应用于找矿、勘查和构造地质研究     

缓倾角红层开挖路堑边坡支护设计中支护力计算

分析了四川盆地缓倾角红层地质结构特征,将下覆泥岩风化形成凹岩腔后的砂岩视为悬臂岩梁,提出了一种计算泥岩风化凹进极限深度及在设计支撑柱时计算支护力的计算方法,并给出一个计算示例。     

大鹏湾叶绿素与生态因子灰关联分析

海水中叶绿素含量和浮游植物(藻类)的个体密度都是海域中初级生产者现存量的指标,这些初级生产者数量的多寡与该海区初级生产力的大小密切相关,其生产力直接或间接地影响水域中其他生物的生产力.     

西藏那曲牧区雪灾损失的多因子灰色关联分析

通过那曲地区牧区雪灾的定性分析,应用灰色系统理论的关联分析方法,以1985年、1995年两次雪灾的平均损失率为参考数列;以气温、降水、稳定的积雪日数、草地退化比例、草场实际载畜量、草地超载比例,冬储草量作为比较数列,对那曲地区雪灾损失进行多因素关联分析。研究结果客观、定量地揭示了雪灾损失与各影响因素之间的相互关系,为那曲地区雪灾的抗灾防灾提供了科学的依据。     

水流作用下斜桩局部冲刷及流场变化试验研究

为研究水流作用下斜桩周围局部冲刷特性及流场变化并掌握斜桩同垂直桩的差异,本研究在不同流速条件下开展了包含反斜桩、垂直桩、正斜桩等多种工况的水槽试验,测量分析了斜桩的冲刷历时曲线、床面形态、沿程流速分布、最大冲刷深度等数据.结果表明:清水条件下斜桩周围局部冲刷坑及桩后沙丘尺度明显减小;斜桩桩前最大冲刷深度随倾角的增加而逐...     

用灰色关联法探讨干旱地区蒸发器的代表性

本文以20m²蒸发池为标准,选定咍地坡站和阿克苏站1982-1988年的部分同期观测资料,研究其它蒸发器的代表性。采用灰色关联法计算各种蒸发器与20m²蒸发器的关联度。结果表明:咍地坡站,ф20cm的关联度最高,其次为ITII-3000;阿克苏站,ITII-3000型关联度最高,其次为E-601。该结果与20m²蒸发量与各型号的线性相关分析结果不同。哈地坡站线性相关系数以ITII-3000最大,其次足E-601;阿克苏站以E-601最大,ITII-3000次之。     

缓倾斜煤层浅部开采破坏的预测与防治

介绍了浅部采动破坏的形成条件和破坏形式。参照国内外情况,提出了缓倾斜煤层浅部采动所形成的陷落性破坏区的判定标准及防治意见。