多震源地震数据偏移成像方法   总被引：1，自引：0，他引：1       下载免费PDF全文

王汉闯  陈生昌  陈国新  梁东辉  佘德平 《地球物理学报》2014,57(3):918-931

多震源地震技术是一种高效的地震数据采集方法技术,得到的地震记录是来自多个震源的混合地震数据.本文在多震源波场传播理论和地震波场满足线性叠加原理的基础上,提出了两种多震源地震数据的偏移成像方法.第一种方法是首先对多震源地震数据进行分离,得到各个单震源的地震数据,然后再利用常规的偏移成像方法进行处理;第二种方法是多震源地震数据的直接偏移成像.把本文提出的多震源偏移成像方法应用于数值模拟的多震源地震数据,验证了本文方法的正确性和有效性,直接偏移成像方法较分离后再偏移方法具有更高的计算效率.  相似文献   

甘肃氡突变型变化成因及其预报效能分析          下载免费PDF全文

曹玲玲 《地震工程学报》2010,32(3):286-291

氡的突变型变化是地震短临预报的主要依据。通过对甘肃省17个氡测点的突变型变化进行分析,发现引起氡突变的成因有干扰因素(温度、降雨、流量、观测仪器以及人为因素等)和地震。除5个测点干扰因素引起的氡突变比例比较高(≥50%)外,其它测点的成因大部分不明确。除连城水氡点外其它单个测点对应地震事件不明显。分区多井成组突变分析结果显示甘东南地区突变点成组项次达到5项并逐月增加可能会发生地震,而祁连山地区并没有此特征。  相似文献   

'Just‐in‐time’ in Australia: a review     

G. J. R. Linge 《The Australian geographer》1991,22(1):67-74

Just‐in‐time (JIT) became a widely used phrase in the 1980s but the ideas underlying it have received little attention from Australian geographers. It is often perceived as simply a system of increasing the efficiency of factories whereas, in reality, it involves changes to systems of firms across a broad range of sectors. This paper explains the meaning of JIT, reviews the literature on this topic in Australia, and suggests that it may return some cohesion to the study of ‘economic geography’ and provide a catalyst for resolving the growing tensions between time and place.  相似文献   

If we are to prosper,the economy must become more productive     

G. J. R. Linge 《The Australian geographer》1991,22(2):105-108

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一种基于三角形运动分块的HEVC视频编码方法     

刘梅锋  钟国韵  徐洪珍 《华东地质学院学报》2014,(3):310-315

分析了目前H.264/AVC已有的非规则运动分块方法的优缺点,根据高效率视频编码（High Efficiency Video Coding,缩写HEVC）标准,提出了三角形的帧间预测单元（Prediction Unit-PU）运动分块,相比常规的PU运动分块,它的斜边更适合一些场景中有着斜边的运动对象,从而提高编码效率。根据该三角形的运动分块形状,提出三角形PU运动分块的运动向量预测方法和运动估计方法。通过分析斜边将产生的块效应方向,相应地提出了优化HEVC滤波方法。实验结果显示,相比已有的非规则运动分块的编码方法,在编码时间平均上升23%的前提下,本算法在BD-rate方面平均降低了2.1%。  相似文献   

Challenging the Coproduction of Virtual Water and Palestinian Agriculture     

《Geoforum》2017

The idiom of virtual water feeds a prolific literature now shaping the policies of national administrations and international organizations, including donors. This article explores the manner in which Palestinian agriculture and the concept of virtual water shed light on each other’s coproduction. It opens the black box of virtual water to identify the underlying hypotheses. It invalidates these hypotheses using empirical research. Integrating structuration theory to an STS approach, it explores the manner the coproduction of an interpretive scheme, virtual water, is linked to the construction of a structure of power. Within the idiom of virtual water, flows exist only through the international trade of commodities while states are endowed with an annually renewed stock of water. We focus on the real flow of water from its emergence from the earth to its evapotranspiration by a cultivated plant. We demonstrate that social and political variables within water governance determine the volumes of virtual water flows far more than climatic or agronomic variables. The idiom of virtual water portrays Palestinian smallholders as inefficient water users while ignoring the manner they sustain food security and environmental sustainability. It legitimizes export oriented agribusinesses as their mode of production corresponds to the coproduction of the idea of efficiency underlying the concept of virtual water. These results allow us to reconsider smallholder agriculture as it exists in the Palestinian territories and what sort of policies can support it.  相似文献   

Excess capacity and efficiency in the quota managed Tasmanian Rock Lobster Fishery     

《Marine Policy》2017

Excess capacity is a major concern for fisheries management worldwide. It is often argued that Individual Transferable Quota (ITQ) systems will enhance efficiency and alleviate problems of excess capacity. While improvements in efficiency have been observed, most empirical studies have found only modest changes in excess capacity as a result of such systems. Using a database of compulsory log-book information for the Tasmanian Rock Lobster Fishery in Australia, from January 2000 to December 2013, this study presents the first analysis to investigate the dynamic behaviour of both excess capacity and efficiency (i.e. technical and scale efficiency) in an industrialised fleet after the introduction of quota management. The analysis revealed weak evidence for a prolonged adjustment in the fishery following the introduction of an ITQ system. In addition, no marked changes in excess capacity were observed over the study period; and furthermore, there was no evidence for an increase in excess capacity during a period of non-binding Total Allowable Catch (TAC) when race to fish behaviour increased in the fishery. The results suggest a limited ability of the ITQ system to alleviate levels of excess capacity in fisheries in the long-term.  相似文献   

新沂台地电阻率观测的新背景场效能评价     

李飞  秦磊  杨冯威 《震灾防御技术》2015,10(2):447-454

根据中国地震局电磁学科技术管理组制定的《地电台站观测效能评估方案》,对新沂台地电阻率新场地观测效能进行了全面评价。从评价结果来看,新沂地震台地电阻率新场地远离或避开蔬菜大棚,有效地避免了蔬菜大棚的影响,台址结构条件、电磁环境、台站观测系统等均符合地电阻率台站建设规范要求,地电阻率观测精度符合异常识别的指标要求。新场地在2013年的试运行中能够记录到十分清晰的区域应力场调整,随着时间的推移,其观测数据对本区及邻近地区的地震监测、预报和地震科学研究将发挥更加重要的作用。  相似文献   

中国入境旅游发展效率及其影响因素研究     

何昭丽  孙慧  张振龙 《干旱区地理》2017,40(6):1282-1289

为了更好地提高旅游专业化水平,运用随机前沿分析技术,根据2004-2014年跨省面板数据,测算了中国入境旅游发展效率,全面分析了入境旅游发展效率的区域特征及影响因素。结果表明：中国入境旅游发展效率较低,呈现低位小幅波动特征;东部、中部、西部的技术效率分别为0.65,0.49,0.4,中部效率为中间水平,技术效率东西差异明显;旅游资源品位、贸易开放度对中国入境旅游发展效率的正向影响最明显,交通状况、外资开放度、产业环境对入境旅游发展的正向影响相对较小;针对研究结论提出政策建议。  相似文献   

Is REDD+ effective,efficient, and equitable? Learning from a REDD+ project in Northern Cambodia     

《Geoforum》2017

REDD+ is a global scale climate change mitigation program aiming at creating financial values for carbon stored in forests. According to the proponents, REDD+ is an effective, efficient, and equitable mechanism for reducing emissions from deforestation and forest degradation. Some scholars question this assumption, and some call for further analysis to understand how REDD+ can contribute to economic, environmental, and social goals, and what are the synergies and trade-offs between them. The purpose of this paper is to contribute to the debate about whether REDD+ projects can be brought to accommodate economic (efficiency), environmental (effectiveness), and social (equity) concerns at the same time by drawing on own field results from a REDD+ project in Cambodia. The paper follows three tracks. The first is to develop and explain the conceptual and analytical framework for our empirical investigations. The second is to explain the field results. The third track is to discuss what general lessons can be learnt. Our case illustrates some of the mechanisms that are likely to work against the willingness and ability of REDD+ projects to ensure local people’s net-gains, and the risk that effectiveness and equity will suffer if REDD+ projects rely solely on the private market. Our case thus indicates a tension between the objectives of creating financial value from carbon stored in trees through the private market, and environmental and social equity concerns. However, we call for more comparative studies of REDD+ projects, and hope our conceptual framework can assist such studies.  相似文献