A theoretical extraction scheme of transport information based on exclusion models     

陈华  杜磊  曲成立  李伟华  何亮  陈文豪  孙鹏 《海洋学报(英文版)》2010,29(11)

In order to explore how to extract more transport information from current fluctuation, a theoretical extraction scheme is presented in a single barrier structure based on exclusion models, which include counter-flows model and tunnel model. The first four cumulants of these two exclusion models are computed in a single barrier structure, and their characteristics are obtained. A scheme with the help of the first three cumulants is devised to check a transport process to follow the counter-flows model, the tunnel model or neither of them. Time series generated by Monte Carlo techniques is adopted to validate the abstraction procedure, and the result is reasonable.  相似文献   

微炭屑的几种统计方法比较及其对人类活动的指示意义   总被引：4，自引：1，他引：3       下载免费PDF全文

李宜垠  侯树芳  赵鹏飞 《第四纪研究》2010,30(2):356-363

微炭屑是研究火的历史和过去人类活动、重建古生态的一项重要指标。它一般指长轴小于120μm、黑色不透明的炭化颗粒。常用点接触法（11刻点和202刻点）、图像识别法、颗粒计数法和分粒级法进行微炭屑统计。本文利用不同方法求得的微炭屑面积浓度或颗粒浓度曲线显著相关,相关系数在0.6以上（p<0.05）,表明这几种方法的微炭屑统计结果具有相似的变化趋势,尤其是两种点接触法与图像识别法的统计结果更加相近,相关系数分别为0.79与0.88;  颗粒计数法与点接触法、图像识别法的相关系数是0.75和0.74。分粒级法与点接触法、图像识别法和颗粒计数法的相关性随着粒级的变化而不同。两种点接触法的微炭屑统计结果的相关系数高达0.93,反映了这两种方法所得微炭屑统计结果具有几乎相同的变化趋势。202刻点接触法由于与其他统计法的相关性都比较高,统计视域多且鉴定统计速度快,是进行微炭屑统计的最佳方法。微炭屑浓度高的时段出现在繁荣的文化期,可能指示着强烈的人类活动。  相似文献   

面向用户对象的CORS运维服务综合体系研究     

高奋生  王芙蓉  周亮  郭际明 《测绘科学》2012,(4):79-81,84

随着国家、省、市各级CORS的不断建设,如何便捷高效维护CORS基础平台,充分发挥CORS的服务效能已成为当前需要解决的一个重要问题,本文在大量调研分析的基础上,结合NJCORS运维经验,提出了面向用户对象的CORS运维服务综合体系,并基于该体系理念,构建完成了基于B/S架构的“南京市连续运行基准站网运维与位置服务系统...  相似文献   

霍山县县域范围内不同空间尺度下农田土壤有机碳变异分析   总被引：3，自引：1，他引：2  

李典友  陈良松  李军  倪建华  李小刚  潘根兴  陆保国  黄登林  孙贤斌 《地理研究》2012,31(9):1571-1579

基于安徽省霍山县第二次土壤普查数据,提取2005～2008年耕地监测数据资料建成土壤有机碳含量数据库,对耕地监测的有机碳数据按县域内不同空间尺度进行了统计分析。结果表明:20年来该县农田表土有机碳含量明显提高,显示农田土壤的有机碳库积累。县域范围内耕地土壤有机碳含量的不同尺度的变异系数介于4.53%～14.91%。村民组(自然村)单元内变异性最高,有机碳含量乡镇间变异性低于行政村间变异性。因此,从县级尺度的农田土壤碳计量来说,以乡镇尺度采样研究比村级尺度可靠性要高。影响县域内农田土壤有机碳含量与变异的动力因子主要是农业利用和农田基本建设,茶、桑和水稻利用下农田土壤有机碳含量明显较高。  相似文献   

Estimating fractal dimension of lineaments using box counting method for the Indian landmass     

V. Jaya  S. Sonika Mohan 《国际地球制图》2013,28(3):314-331

A fractal in general is a scale-invariant object that has an underlying power-law equation and is characterized by a positive fractal dimension. The fractal dimension of the Indian landmass is evaluated from the lineament map by utilizing the MATLAB programme for box counting method. The lineament map of India is divided into grids. The fractal dimension of each grid is obtained and the values are mapped. Most of the regions of India has fractal dimension in the range 1–1.25. The fractal values are compared with b-value in Gutenberg–Richter equation which gives a relationship between frequency of occurrence of earthquake and its magnitude. The estimation of b-value requires a complete earthquake dataset. In regions where the complete earthquake data are not available, the fractal dimension evaluated from the study can be used as a parameter to assess the seismic hazard of the region.  相似文献   

A split-beam echo-counting model for riverine use     

Mulligan  Timothy J.; Kieser  Robert 《ICES Journal of Marine Science》1996,53(2):403-406

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An improvement in the small-volume technique for determining thorium-234 in seawater   总被引：3，自引：0，他引：3  

Pinghe Cai  Minhan Dai  Dongwei Lv  Weifang Chen 《Marine Chemistry》2006,100(3-4):282

The recently developed 2–5 L small-volume MnO₂ coprecipitation method for determining ²³⁴Th in seawater has provided a new way to substantially increase, both temporally and spatially, the sampling resolution of ²³⁴Th and ²³⁴Th-based particulate organic carbon export estimates in the upper ocean. In this study, we further optimize the technique by reducing reagent quantities and the use of an additional water bath heating step. This optimization allows the filtration of the MnO₂ precipitate onto a 25-mm diameter, 1.0 μm pore size QMA filter to be completed within < 30 min for unfiltered waters from the South China Sea. In addition, we have modified the MnO₂ purification procedure to allow for alpha spectrometric measurements of ²³⁴Th recoveries. Results from recovery experiments suggest that reagent amounts can be reduced to 0.0375 mg KMnO₄ and 0.1 mg MnCl₂·4H₂O per liter of sample, while still maintaining high ²³⁴Th recovery. This study further confirms that the addition of a yield monitor is necessary for the application of the small-volume method.  相似文献   

基于实测应力的半潜平台疲劳损伤分析     

武博  王璞  李欣  杨建民 《海洋工程》2020,38(2):17-26

疲劳破坏是海洋结构物发生破坏的一种主要形式,深水半潜平台在海上运输、作业、停滞时会受到交变的风、浪、流载荷作用,进而引起结构关键节点处的疲劳损伤,影响平台安全性。以"海洋石油981"半潜钻井平台为研究对象,利用光纤光栅应变传感器对结构高应力区进行应力监测,获取测点处应力时历数据。将监测位置划分为四个监测板块,采用四点雨流计数法对测点应力进行处理,得到以离散形式给出的应力循环幅度与相应循环周次。参照DNV《海上钢结构疲劳设计规范》推荐的S-N曲线,基于Miner线性疲劳累计损伤原则,得到各个测点处的总体疲劳损伤度。选取具有最大疲劳损伤度的危险测点,并结合海上实测总时长,预测半潜平台的总体疲劳寿命。  相似文献   

Electricity regulation in the Chinese national emissions trading scheme (ETS): lessons for carbon leakage and linkage with the EU ETS     

Yingying Zeng  Stefan E. Weishaar  Hans H. B. Vedder 《Climate Policy》2018,18(10):1246-1259

Carbon leakage is central to the discussion on how to mitigate climate change. The current carbon leakage literature focuses largely on industrial production, and less attention has been given to carbon leakage from the electricity sector (the largest source of carbon emissions in China). Moreover, very few studies have examined in detail electricity regulation in the Chinese national emissions trading system (which leads, for example, to double counting) or addressed its implications for potential linkage between the EU and Chinese emissions trading systems (ETSs). This article seeks to fill this gap by analysing the problem of ‘carbon leakage’ from the electricity sector under the China ETS. Specifically, a Law & Economics approach is applied to scrutinize legal documents on electricity/carbon regulation and examine the economic incentive structures of stakeholders in the inter-/intra-regional electricity markets. Two forms of ‘electricity carbon leakage’ are identified and further supported by legal evidence and practical cases. Moreover, the article assesses the environmental and economic implications for the EU of potential linkage between the world’s two largest ETSs. In response, policy suggestions are proposed to address electricity carbon leakage, differentiating leakage according to its sources.

Key policy insights

• Electricity carbon leakage in China remains a serious issue that has yet to receive sufficient attention.

• Such leakage arises from the current electricity/carbon regulatory framework in China and jeopardizes mitigation efforts.

• With the US retreat on climate efforts, evidence suggests that EU officials are looking to China and expect an expanded carbon market to reinforce EU global climate leadership.

• Given that the Chinese ETS will be twice the size of the EU ETS, a small amount of carbon leakage in China could have significant repercussions. Electricity carbon leakage should thus be considered in any future EU–China linking negotiations.

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Counting chronology and climate records with about 1000 annual layers of a Holocene stalagmite from the Water Cave in Liaoning Province, Chinaannual layers of a Holocene stalagmite from the Water Cave in Liaoning Province, China     

Juzhi Hou  Ming Tan  Dongsheng Liu 《中国科学D辑(英文版)》2002,45(5):385-391

One active stalagmite from the Water Cave in Liaoning Province contains growth layers of three sizes. Based on thermal ionization mass spectrometry ²³⁰Th dating, we found that middle size layers are annual layers, with each middle layer consisting of one narrow dark layer and a wide bright layer. The small layers within middle layers are sub-annual layers and the large layers are multi-year layers. Based on the layer-counting method, we established a high-resolution time scale for layer thickness. Our results reveal two dramatic century-scale climate cycles over the past 1000 years in this region.  相似文献