RY-3溶氧仪测试结果分析   总被引：1，自引：0，他引：1  

滕怀德  龚德俊  李维森  徐永平 《海洋科学》1995,(5):7-60

给出了作者研制的ＲＹ－３溶解氧测试仪的银极电位与美国 ＹＳＩ－５８溶氧仪 的银极电位（在海水中均以甘汞电极为参比电极）对比测试的误差分析，对ＲＹ－３溶 氧仪与ＹＳＩ－５８溶氧仪现场对比测试的结果进行误差分析。并介绍了国家标准物质 研究中心和青岛计量测试所对ＲＹ－３溶氧仪的测试结果。  相似文献   

长江口水下淡水资源及其供水意义   总被引：3，自引：0，他引：3       下载免费PDF全文

龚士良  茅鸿妹 《海洋开发与管理》1995,12(2):54-56

上海地区发育的含水砂层均为长江水系古河道，其一直延伸至长江口、杭州湾水域，尤以埋深１７０ｍ以下的含水层分布更广，成为水下淡水资源的赋存场所。初勘结果表明，其水量丰富、水质优良，从而为海上及岛屿供水提供了新途径。  相似文献   

中国北方2021年3月中旬持续性沙尘天气的特征及其成因   总被引：2，自引：2，他引：0  

杨晓军  张强  叶培龙  秦豪君  徐丽丽  马莉  巩崇水 《中国沙漠》2021,41(3):245-255

沙尘天气是多发于中国北方春季的灾害性天气,严重危害农业生产、交通运输、空气质量和人民的生命财产安全,长期受到社会各界的广泛关注。利用多源多尺度数据,采用天气学分析、物理量诊断、轨迹分析等方法对2021年3月中旬西北地区东部一次持续性沙尘重污染天气的成因进行了深入分析。结果表明：（1）受强烈发展的蒙古气旋影响,蒙古国南部及中国内蒙古中西部地区于3月14日首先出现强沙尘暴天气,并将沙尘传输至中国西北、华北、东北一带,西北东部的沙尘天气维持达到5 d。（2）沙尘天气维持期,西北东部中低层以弱上升运动为主,大气层结稳定,且西北东部不断有弱锋生发展,不利于沙尘的沉降;自北向南分布的银川、中卫、兰州3站的垂直螺旋度的波动与污染浓度的变化基本一致;混合层高度较其气候平均值明显偏低,不利于大气湍流发展。（3）此次影响西北东部的沙尘主要由蒙古国输入,近20年中蒙边境、蒙古国南部的植被减少可能是此次沙尘天气的沙源主要来自蒙古国南部的原因。  相似文献   

Driving force and changing trends of vegetation phenology in the Loess Plateau of China from 2000 to 2010     

Hao Wang  Guo-hua Liu  Zong-shan Li  Xin Ye  Meng Wang  Li Gong 《山地科学学报》2016,13(5):844-856

Changes in vegetation phenology are key indicators of the response of ecosystems to climate change. Therefore, knowledge of growing seasons is essential to predict ecosystem changes, especially for regions with a fragile ecosystem such as the Loess Plateau. In this study, based on the normalized difference vegetation index (NDVI) data, we estimated and analyzed the vegetation phenology in the Loess Plateau from 2000 to 2010 for the beginning, length, and end of the growing season, measuring changes in trends and their relationship to climatic factors. The results show that for 54.84% of the vegetation, the trend was an advancement of the beginning of the growing season (BGS), while for 67.64% the trend was a delay in the end of the growing season (EGS). The length of the growing season (LGS) was extended for 66.28% of the vegetation in the plateau. While the temperature is important for the vegetation to begin the growing season in this region, warmer climate may lead to drought and can become a limiting factor for vegetation growth. We found that increased precipitation benefits the advancement of the BGS in this area. Areas with a delayed EGS indicated that the appropriate temperature and rainfall in autumn or winter enhanced photosynthesis and extended the growth process. A positive correlation with precipitation was found for 76.53% of the areas with an extended LGS, indicating that precipitation is one of the key factors in changes in the vegetation phenology in this water-limited region. Precipitation plays an important role in determining the phenological activities of the vegetation in arid and semiarid areas, such as the Loess Plateau. The extended growing season will significantly influence both the vegetation productivity and the carbon fixation capacity in this region.  相似文献   

黏土失水开裂演化过程的影响试验     

谢建宝  姚亚辉  龚绪龙 《江苏地质》2016,40(2):346-351

裂隙性为黏土的主要特性之一。探讨黏土的开裂规律,对于分析地裂缝成因机理,开展预测研究具有重要的理论意义和工程价值。通过室内试验,研究了黏土干燥收缩过程中含水率的变化规律。分别制备不同厚度、宽度、含砂量的试样,获得不同条件下黏土失水过程含水率的变化规律。在试验所设定的条件下,土体开裂时的含水率很接近,平均约为33.48%;当样品宽度不变时,土层越厚,含水率变化速率越小;当样品厚度相同时,宽度不同,含水率变化速率几乎相同;当厚度、宽度都相同时,含水率变化速率随含砂量的增大而减小。对于同一样品,土体厚度越大,样品裂隙率越小;土体厚度相同时,样品的裂隙率随着样品宽度的增大先减小后增大,且样品的开裂周期与样品的裂隙率同步变化。  相似文献   

Discovery of Palaeozoic Karsts in the Qaidam Basin and Their Oil and Gas Prospects     

PENG Bo  LIU Chenglin  LI Zongxing  MA Yinsheng  CAO Jun  WANG Bing  ZHANG Xu 《《地质学报》英文版》2016,90(5):1919-1920

正Objective Complex geological factors have been constraining the oil and gas exploration in the Paleozoic strata of the Qaidam Basin,although there are high-quality hydrocarbon source rocks.One of the most important reasons may be reservoir densification due to the multiple stages of destructive cementation,which has hindered our understanding of the Paleozoic petroleum enrichment rules in the Qaidam basin.In recent years,the petroleum  相似文献   

Recent research progress and prospects in tourism geography of China   总被引：1，自引：1，他引：0  

Lin Lu  Jie Bao  Jianfeng Huang  Qijing Zhu  Chenglin Mu  Xiaole Chu  Yan Xu  Xiaoli Zha 《地理学报(英文版)》2016,26(8):1197-1222

Based on a large number of domestic literature reviews with related research abroad, academic standards and issues awareness have been intensified in domestic tourism geography, disciplinary consciousness and innovation enhancement. Hence, some valuable achievements have been made in the areas of tourism resources, tourism regional system, the spatial structure of tourism, tourism flow, ecotourism, tourism industry, tourism planning and tourism impacts, which strengthened the traditional advantages of research, expanded new areas of research and made research trends diverse. Meanwhile, with innovation of research methods, tourism geography in China is getting more and more internationally-oriented and reflecting Chinese characteristics. Research trends of China’s tourism geography are prospected: 1) Catering to national strategic needs, persisting problem-oriented, strengthening the metatheoretical research, and building Chinese “localization” of theory of tourism geography and method system. 2) Introducing and assimilating foreign theories and research methods, while focusing on explaining new tourism phenomena and problems in the domestic socio-economic background. 3) Concerning about the new regional spatial processes of demographic process, social process, and spatial process in new tourism trend. 4) Exploring interactive process and mechanism of man-land relationship and new models to develop territorial space under the tourism impacts. 5) Exploring important research issues of tourism geography in global, national, regional and local scales, from the point of view of spatial differentiation, scale transformation, interaction of man and nature, creating tourism geography interpretation system based on “process-structure-mechanism” of China. 6) Building theoretical system actively, while strengthening application-oriented research, and focusing on tourism poverty alleviation, tourism and heritage protection, national parks’ construction and other hot issues. Faced with econometrics research boom, we should return to rational thinking, using big data scientifically, while paying attention to the important role of qualitative evaluation in future research.  相似文献   

Incorporating spatial interaction patterns in classifying and understanding urban land use   总被引：4，自引：0，他引：4  

Xi Liu  Chaogui Kang  Li Gong 《International journal of geographical information science》2016,30(2):334-350

Land use classification has benefited from the emerging big data, such as mobile phone records and taxi trajectories. Temporal activity variations derived from these data have been used to interpret and understand the land use of parcels from the perspective of social functions, complementing the outcome of traditional remote sensing methods. However, spatial interaction patterns between parcels, which could depict land uses from a perspective of connections, have rarely been examined and analysed. To leverage spatial interaction information contained in the above-mentioned massive data sets, we propose a novel unsupervised land use classification method with a new type of place signature. Based on the observation that spatial interaction patterns between places of two specific land uses are similar, the new place signature improves land use classification by trading off between aggregated temporal activity variations and detailed spatial interactions among places. The method is validated with a case study using taxi trip data from Shanghai.  相似文献   

Optimizing precipitation station location: a case study of the Jinsha River Basin     

Ke Wang  Daoqin Tong  Kai Wang  Wei Wang  Jianya Gong 《International journal of geographical information science》2016,30(6):1207-1227

Precipitation stations are important components of a hydrological monitoring network. Given their critical role in rainfall forecasting and flood warnings, along with limited observation resources, determining the optimal locations to deploy precipitation stations presents an important problem. In this paper, we use a maximal covering location problem to identify the best precipitation station sites. Considering the terrain conditions and the characteristics of a rainfall network, the original maximal covering location model is modified with the introduction of a set of additional constraints. The minimum density requirement is used to determine a precipitation station’s coverage range, and three weighting schemes are used to evaluate each demand object’s covering priority. As a typical mountainous watershed with high annual precipitation, the Jinsha River Basin is selected as the study area to test the applicability of the proposed method. Results show that the proposed method is effective for precipitation station configuration optimization, and the model solution achieves higher coverage than the real-world deployment. Compared with the commercial solver CPLEX, a genetic algorithm-based heuristic can significantly reduce the computation time when the problem size is large. Several deployment strategies are also discussed for establishing the optimal configuration of precipitation stations.  相似文献   

高密度电法在工程地质中的应用二例     

李亚东  YANG Gong  尹保忠 《云南地质》2008,27(1):81-85

硅灰石矿和水库工程地质中应用高密度电阻率法,资料数据处理快捷准确,推测拟断面成果可靠。  相似文献