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321.
Yingjie Hu Krzysztof Janowicz Yuqi Chen 《International journal of geographical information science》2016,30(6):1228-1249
Recent years have witnessed a large increase in the amount of information available from the Web and many other sources. Such an information deluge presents a challenge for individuals who have to identify useful information items to complete particular tasks in hand. Information value theory (IVT) from economics and artificial intelligence has provided some guidance on this issue. However, existing IVT studies often focus on monetary values, while ignoring the spatiotemporal properties which can play important roles in everyday tasks. In this paper, we propose a theoretical framework for task-oriented information value measurement. This framework integrates IVT with the space-time prism from time geography and measures the value of information based on its impact on an individual’s space-time prisms and its capability of improving task planning. We develop and formalize this framework by extending the utility function from space-time accessibility studies and elaborate it using a simplified example from time geography. We conduct a simulation on a real-world transportation network using the proposed framework. Our research could be applied to improving information display on small-screen mobile devices (e.g., smartwatches) by assigning priorities to different information items. 相似文献
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324.
湘江中下游农田土壤和蔬菜的重金属污染 总被引:11,自引:0,他引:11
A total of 219 agricultural soil and 48 vegetable samples were collected from the midstream and downstream of the Xiangjiang River(the Hengyang-Changsha section)in Hunan Province.The accumulation characteristics,spatial distribution and potential risk of heavy metals in the agricultural soils and vegetables were depicted.There are higher accumulations of heavy metals such as As,Cd,Cu,Ni,Pb and Zn in agricultural soils,and the contents of Cd(2.44 mg kg^-1 ),Pb(65.00 mg kg^-1 )and Zn(144.13 mg kg^-1 )are 7.97,3.69 and 1.63 times the corresponding background contents in soils of Hunan Province,respectively. 13.2%of As,68.5%of Cd,2.7%of Cu,2.7%of Ni,8.7%of Pb and 15.1%of Zn in soil samples from the investigated sites exceeded the maximum allowable heavy metal contents in the China Environmental Quality Standard for Soils(GB15618-1995,Grade Ⅱ).The pollution characteristics of multi-metals in soils are mainly due to Cd.The contents of As,Cd,Cu,Pb and Zn in vegetable soils are significantly higher than the contents in paddy soils.95.8%, 68.8%,10.4%and 95.8%of vegetable samples exceeded the Maximum Levels of Contaminants in Foods(GB2762-2005)for As,Cd,Ni and Pb concentrations,respectively.There are significantly positive correlations between the concentrations of Cd,Pb and Zn in vegetables and the concentrations in the corresponding vegetable soils(p〈0.01).It is very necessary to focus on the potential risk of heavy metals for food safety and human health in agricultural soils and vegetables in the midstream and downstream of the Xiangjiang River,Hunan Province of China. 相似文献
325.
西藏自治区贡觉县雄松乡至沙东乡金沙江流域作为川藏铁路的必经河流,地形崎岖、地质灾害隐患点多,亟需对该地区隐患点进行全方位的识别。首先,选取61景哨兵一号(Sentinel-1)升轨影像、53景Sentinel-1降轨影像和7景陆地观测技术卫星2号(advanced land observing satellite 2,ALOS-2)升轨影像对研究区域进行滑坡探测与监测。然后,利用合成孔径雷达(interferometric synthetic aperture radar,InSAR)通用型大气改正在线服务(generic atmospheric correction online service for InSAR,GACOS)辅助干涉影像堆叠技术(InSAR Stacking)的方法,获取研究区域雷达视线(line of sight, LOS)方向的InSAR年形变平均速率图,并结合3个轨道的结果提取出沿坡向和垂直滑坡向的平均速率图。最后,与LiCSBAS时间序列分析包的结果进行比较,发现两者具有高度一致性,LOS向年形变速率图像的相关系数在0.92以上,沿坡向和沿垂直滑坡向年形变速率的相关系数在0.85以上,证明了GACOS辅助下InSAR Stacking结果的可靠性。此外,还发现研究区域内沿坡向最大年形变速率为-163 mm/a;结合InSAR形变结果与光学遥感影像解译,可将该滑坡群分为A~G 7个区域进行实时监测。 相似文献
326.
氢气被认为是反应断裂活动最灵敏的地球化学组分之一。研究影响断裂带氢浓度动态变化的主要因素,是科学分析断裂带氢与构造活动关系的基础工作。本文基于河南内乡马山口断层气氢气浓度与辅助测项的连续观测资料,重点分析了氢浓度变化与地温、气温、气压的相关关系,确定了主要影响因素。结果表明,氢气浓度日变化极值介于气温和地温之间,极值点靠近地温一侧。使用逐步回归方法分析进一步证明,地温、温度对氢气浓度均有影响,但地温影响更显著,气压影响不显著。总体来讲,氢浓度会受到地温和气温的双重影响,但与地温关系更为密切。 相似文献
327.
Zhi Ding Fenzhen Su Yanan Chen Ying Liu Xue Feng Wenqiu Hu Fengqin Yan He Li Pujia Yu Xuguang Tang 《海洋学报(英文版)》2023,42(2):163-174
Increasing intense human activities have largely changed the coastal landscape and caused many environmental issues. However, whether human-induced activities could change the coastal land use gradient pattern, an important coastal zonal characteristic along the sea–land direction, remains unclear. Manila Bay was selected as the study area in this work. According to the distance of the land use and land cover(LULC) to the coastline, we clustered the typical coastal land use sequence patterns(CLU... 相似文献
328.
Weina Zhao Zhiqiang Wu Fanghui Hou Xunhua Zhang Tianyao Hao Hanjoon Kim Yanpeng Zheng Shanshan Chen Huigang Wang 《海洋学报(英文版)》2023,42(2):104-119
The South Yellow Sea basin is filled with Mesozoic–Cenozoic continental sediments overlying pre-Palaeozoic and Mesozoic–Palaeozoic marine sediments. Conventional multi-channel seismic data cannot describe the velocity structure of the marine residual basin in detail, leading to the lack of a deeper understanding of the distribution and lithology owing to strong energy shielding on the top interface of marine sediments. In this study, we present seismic tomography data from ocean bottom seismogra... 相似文献
329.
Yuting Zhang Shanshan Song Bin Zhang Yang Zhang Miao Tian Ziyi Wu Huorong Chen Guangmao Ding Renyan Liu Jingli Mu 《海洋学报(英文版)》2023,42(2):134-141
Toxic harmful algal blooms(HABs) can cause deleterious effects in marine organisms, threatening the stability of marine ecosystems. It is well known that different strains, natural populations and growth conditions of the same toxic algal species may lead to different amount of phycotoxin production and the ensuing toxicity. To fully assess the ecological risk of toxic HABs, it is of great importance to investigate the toxic effects of phycotoxins in marine organisms. In this study, the short-te... 相似文献
330.
Pengfei Xiong Cong Cheng Zenggui Kuang Jinfeng Ren Jinqiang Liang Hongfei Lai Zigui Chen Jiang Lu Xiaoyu Fang Tao Jiang 《海洋学报(英文版)》2023,42(2):120-133
In the late Miocene, giant ancient pockmarks, which are fairly rare globally, developed in the Qiongdongnan Basin. In this paper, to determine the sedimentary characteristics and genetic mechanism of these giant ancient pockmarks in the Yinggehai Formation of the Qiongdongnan Basin, based on high-resolution 3D seismic data and multiattribute fusion technologies, we analyzed the planar distribution and seismic facies of the ancient pockmarks and compared the characteristics of the ancient pockmar... 相似文献