周至井水位气压效率和相关系数在中强地震前的变化特征   总被引：1，自引：0，他引：1  

王新  赵小茂  张国强  杨旭升 《华南地震》2007,27(4):61-66

计算了2002～2004年周至井水位的气压效率和相关系数,初步分析了其与地震的关系,认为在2002年甘肃玉门5.9级地震、2003年和2004年甘肃岷县5.2、5.0级地震前,该井水位的气压效率和相关系数同时出现了明显的短临前兆异常。  相似文献   

Experimental study of the woody debris trapping efficiency of a steel pipe,open sabo dam     

《国际泥沙研究》2020,35(5):431-443

In recent years, the damage caused to human settlements in Japan by large woody debris (LWD) has been increasing. For example, the 2013 Izu Oshima typhoon resulted in a large number of fatalities and missing persons, and the Kagoshima Typhoon Disaster and Northern Kyusyu torrential downpour caused vast infrastructure damage due to the associated LWD. Current countermeasures for preventing LWD are insufficient to maintain the safety of residential areas. One type of protective barrier, the open sabo dam, has been constructed in Japan during the past 30 years. The primary function of open sabo dams is to block the flow of boulders, thereby also reducing sediment flow by reducing the gap size. However, because Japanese open sabo dams are designed specifically for boulder-trapping, the ability of these dams to trap LWD remains uncertain. In particular, many problems have been reported with respect to sediment trapping by driftwood with roots in an open sabo dam setting. The objective of this study was to examine the trapping efficiency of open sabo dams for LWD and sediment. The experimental approach clarified the influence of driftwood, without and with roots, on sediment trapping for a straight-channel flume. The flexible roots of the driftwood were shown to have a significant effect on the sediment trapping efficiency of the dam.  相似文献   

EGM96/2008重力场模型在似大地水准面构建中的应用     

王鸣鹤  孙成志  许丹萍  吴晓倩 《北京测绘》2020,(5):687-690

似大地水准面的构建可以将GPS测量的高程迅速转化为正常高,极大降低高程测量的成本,提高相关工作效率。将EGM96/2008重力场模型与“移去-恢复”法相结合,在矿区内建立似大地水准面,并使用不同的插值方法,验证最优方案。结果表明,使用二次线性插值的EGM2008重力场模型拟合效果更好,模型外符合精度达到3.6 mm,更适合应用于该区域似大地水准面构建。  相似文献   

岩溶断陷盆地不同海拔植物水分利用效率分析   总被引：1，自引：0，他引：1  

梁锦桃  邓艳  李旭尧  徐烨  曹建华 《中国岩溶》2020,39(2):180-188

为探讨不同海拔高度的养分、环境要素与植物水分利用效率变化的关系，以岩溶断陷盆地云南小江流域的乔木、灌木、草本为研究对象，分析水分利用效率和叶片养分浓度随海拔的变化情况。结果表明:（1）研究区内海拔2 000 m处的草本植物的叶片δ13C值最高，2 200 m处的乔木的叶片δ13C值最低；（2）海拔高度对乔木、灌木的植物水分利用效率影响大于草本植物，草本植物的水分利用效率随海拔高度的变化甚微，两者之间的拟合度较小；高值区出现在海拔为2 200 m处的乔木；低值区出现在海拔为2 000 m处的草本植物；（3）不同海拔水分利用效率与叶片N、P浓度的相关性较弱（与叶片的N浓度呈弱正相关，与叶片的P浓度呈弱负相关）；（4）不同海拔水分利用效率与各气候因子的相关性较弱，与多年平均气温、多年平均降雨量、多年平均日照时数均呈弱正相关。   相似文献   

可持续发展中的公平与效率问题   总被引：3，自引：0，他引：3  

梁彤伟  李露亮 《地域研究与开发》1998,17(1):31-34

在传统增长方式中,公平与效率之间存在着巨大的冲突,由于可持续发展的出现,才第一次把两者纳入到可以相互补充、相互协调的框架之内,从而构成了整个社会得以生存与发展的必要张力。如何在公平的价值观念下效率,如何在有效的市场中保证公平,成为环境与发展问题相并列的当代经济理论、经济伦理思想以及可持续发展观的重要课题。  相似文献   

Sustainable development and mine management     

Carmine Nappi  Richard Poulin 《Natural Resources Research》1998,7(4):263-269

The sustainable development concept has generated a large body of literature. It has also divided economists into numerous schools of thought. The neoclassical, London, and other schools are painted in broad strokes in the first part of this paper. They debate the extent to which manufactured capital and “natural” capital are believed to be substitutes or complements in a macroeconomics context. The problem stems from the difficulty to measure “natural” capital. The second part of the paper looks at sustainable development in mining at the firm level. First, it is argued that the capital value of the mineral reserves can be maintained by discovering reserves or by saving part of the rent. Second, we show that mine manager actions can be induced to follow efficiency and equity principles when proper limits or constraints are imposed by the legislator. It is concluded that a set of indicators need to be defined and calibrated to ensure that the economic, environmental, and social limits imposed on the mine manager become a framework inside which he competes for the best interest of the firm.  相似文献   

统一分布下的LP估计抗差测度     

周世健  陈永奇 《华东地质学院学报》1998,21(3):258-264

本文根据定位参数Ｍ估计理论,导出了ＬＰ估计的影响函数,分析了ＬＰ估计的抗差能力,同时还推导了ＬＰ估计的渐近效率,综合抗差能力和效率,分析了ＬＰ估计的优劣性,明确指出,用现测数据中含有粗差扰动的数据和Ｐ为（１,１．２５）的ＬＰ估计进行处理,结果较优,效率较高。  相似文献   

南京九华山铜矿伴生金的赋存状态及分布规律     

黄松  陈德松 《矿产与地质》1998,12(2):101-105

九华山铜矿床中伴生金已具综合利用价值。金以矿物态为主,金矿物主要为银金矿、含银自然金。金矿物粒度较细,大于２００目者占２４．３４％,金矿物主要嵌布于黄铜矿粒间或裂隙中。金的理想回收率为６６．３０％,空间分布上,沿矿体走向金西低东高,倾向金北高南低,深度金随深度增加而增加。  相似文献   

Kinetic shear resistance,fluid pressures and radiation efficiency during seismic faulting   总被引：1，自引：0，他引：1  

Richard H. Sibson 《Pure and Applied Geophysics》1977,115(1-2):387-400

Summary During earthquake faulting, radiation efficiency and the degree stress relief are critically dependent on the kinetic shear resistance. This is often assumed to stay constant during slip, but geological evidence suggests that for moderate or large shallow earthquakes it may decrease dramatically to near-zero values once slip is initiated, either by melt formation or by transient increases in fluid pressure on the fault plane. The latter, probably more common process may arise partly through an interaction between temperature and water pressure, and partly through dilatancy recovery as shear stress is relieved. If the fault remains undrained, stress relief should be absolute with seismic efficiency reaching high values, so that stress drops give a measure of the level of tectonic shear stress in fault zones. Supporting evidence comes from the observation that apparent stress is generally about half the stress drop.  相似文献   

城市群创新联系网络结构与创新效率研究   总被引：4，自引：4，他引：4  

盛彦文  苟倩  宋金平 《地理科学》2020,40(11):1831-1839

引入修正引力模型、社会网络分析方法、DEA模型以及Tobit模型，探讨2001—2015年京津冀、长三角、珠三角三大城市群的创新联系网络结构对创新效率的影响。研究表明：① 创新联系格局方面，京津冀城市群呈现以“京津”为核心的放射状发展特征，长三角城市群呈现以“Z”字形为主轴的类钻石型空间格局，珠三角城市群形成了以珠江口两侧城市为核心、其他城市为重要节点的空间格局；② 在创新联系网络结构特征方面，京津冀城市群呈极核式发展，群内创新联系高度依赖于核心城市，长三角和珠三角城市群由单中心驱动转变为多中心驱动，呈均衡发展特征，京津冀和珠三角城市群创新联系网络具有“小世界”网络特征；③ Tobit模型回归结果显示，三大城市群中，城市节点在城市群创新联系网络中的中心位置、中介地位、对结构洞的运用能力和集聚程度对其创新效率的影响存在差异。  相似文献