The Experts below are selected from a list of 8385 Experts worldwide ranked by ideXlab platform
Xueqiang Lv - One of the best experts on this subject based on the ideXlab platform.
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Geographical Topics Learning of Geo-Tagged Social Images
IEEE Transactions on Cybernetics, 2016Co-Authors: Xiaoming Zhang, Shufan Ji, Senzhang Wang, Zhoujun Li, Xueqiang LvAbstract:With the availability of cheap location sensors, geotagging of images in online social media is very popular. With a large amount of geo-tagged social images, it is interesting to study how these images are shared across Geographical regions and how the Geographical language Characteristics and vision patterns are distributed across different regions. Unlike textual document, geo-tagged social image contains multiple types of content, i.e., textual description, visual content, and Geographical information. Existing approaches usually mine Geographical Characteristics using a subset of multiple types of image contents or combining those contents linearly, which ignore correlations between different types of contents, and their Geographical distributions. Therefore, in this paper, we propose a novel method to discover Geographical Characteristics of geo-tagged social images using a Geographical topic model called Geographical topic model of social images (GTMSIs). GTMSI integrates multiple types of social image contents as well as the Geographical distributions, in which image topics are modeled based on both vocabulary and visual features. In GTMSI, each region of the image would have its own topic distribution, and hence have its own language model and vision pattern. Experimental results show that our GTMSI could identify interesting topics and vision patterns, as well as provide location prediction and image tagging.
Jong-sung Yoon - One of the best experts on this subject based on the ideXlab platform.
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Study on Storm Surge Using Parametric Model with Geographical Characteristics
Water, 2020Co-Authors: Jong-sung YoonAbstract:The coastal area of Japan has been damaged yearly by storm surges and flooding disasters in the past, including those associated with typhoons. In addition, the scale of damage is increasing rapidly due to the changing global climate and environment. As disasters due to storm surges become increasingly unpredictable, more measures should be taken to prevent serious damage and casualties. The Japanese government published a hazard map manual in 2015 and obligates the creation of a hazard map based on a parametric model as a measure to reduce high-scale storm surges. Parametric model (typhoon model) accounting for the topographical influences of the surroundings is essential for calculating the wind field of a typhoon. In particular, it is necessary to calculate the wind field using a parametric model in order to simulate a virtual typhoon (the largest typhoon) and to improve the reproducibility. Therefore, in this study, the aim was to establish a hazard map by assuming storm surges of the largest scale and to propose a parametric model that considers the changing shape of typhoons due to topography. The main objectives of this study were to analyze the Characteristics of typhoons due to pass through Japan, to develop a parametric model using a combination of Holland’s and Myers’s models that is appropriate for the largest scale of typhoon, and to analyze the parameters of Holland’s model using grid point values (GPVs). Finally, we aimed to propose a method that considers the changing shape of typhoons due to topography. The modeling outcomes of tide levels and storm surge heights show that the reproduced results obtained by the analysis method proposed in this study are more accurate than those obtained using GPVs. In addition, the reproducibility of the proposed model was evaluated showing the high and excellent reproducibility of storm surge height according to the geographic Characteristics.
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Study on Storm Surge Using Parametric Model with Geographical Characteristics
2020Co-Authors: Jong-sung YoonAbstract:Recently, the intensities of natural disasters have increased significantly owing to climate change and various other environmental factors, causing unprecedented damage. Measures must be established to reduce damage from large-scale natural disasters caused by the rapidly changing environment. The Japanese government published a hazard map manual in 2015 and obligates the creation of a hazard map as a measure to reduce high-scale storm surges. This manual presents a typhoon model based on a parametric model that is used to create a hazard map. The Myers model assuming concentric circles, which is primarily used in East Asia, is disadvantageous as it cannot consider geographic Characteristics. Therefore, a new parametric model is necessary to calculate wind and pressure fields, which change according to geographic Characteristics. To improve this limitation of the Myers model, we calculated the wind and pressure fields considering Geographical effects by combining the Holland model, which can consider the size of a developing typhoon, and the Mascon model, which changes by geographic Characteristics. To determine the gradient coefficient of the Holland model, the coefficient that changes every moment was calculated using grid point value data. The result indicated excellent reproducibility of storm surge height according to the geographic Characteristics.
Xiaoming Zhang - One of the best experts on this subject based on the ideXlab platform.
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Geographical Topics Learning of Geo-Tagged Social Images
IEEE Transactions on Cybernetics, 2016Co-Authors: Xiaoming Zhang, Shufan Ji, Senzhang Wang, Zhoujun Li, Xueqiang LvAbstract:With the availability of cheap location sensors, geotagging of images in online social media is very popular. With a large amount of geo-tagged social images, it is interesting to study how these images are shared across Geographical regions and how the Geographical language Characteristics and vision patterns are distributed across different regions. Unlike textual document, geo-tagged social image contains multiple types of content, i.e., textual description, visual content, and Geographical information. Existing approaches usually mine Geographical Characteristics using a subset of multiple types of image contents or combining those contents linearly, which ignore correlations between different types of contents, and their Geographical distributions. Therefore, in this paper, we propose a novel method to discover Geographical Characteristics of geo-tagged social images using a Geographical topic model called Geographical topic model of social images (GTMSIs). GTMSI integrates multiple types of social image contents as well as the Geographical distributions, in which image topics are modeled based on both vocabulary and visual features. In GTMSI, each region of the image would have its own topic distribution, and hence have its own language model and vision pattern. Experimental results show that our GTMSI could identify interesting topics and vision patterns, as well as provide location prediction and image tagging.
Han Qifei - One of the best experts on this subject based on the ideXlab platform.
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eco Geographical Characteristics of alpine timberlines on northern slope of tianshan mountains
Journal of Desert Research, 2012Co-Authors: Han QifeiAbstract:Spatial variation of alpine timberline altitude on northern slope of Tianshan Mountains is confirmed by remote sensing and field survey data,and its eco-Geographical Characteristics are analyzed in this study.Results show that:(1) The altitude of alpine timberlines is between 2 600 m and 2 850 m.It ascends gradually from west to east,and changes significantly from Qitai to Balikun.The width of alpine timberlines in Ili and Manas is wider than that in other regions.(2) The altitude of alpine timberlines is controlled by growing season temperature,i.e.annual biotemperature,mean temperature for the warmest month,mean temperature for growing season.The parameter of annual biotemperature is better to indicate the altitude of alpine timberline than other parameters.The values of parameters are all within the range of the average values across China.The main factor influencing forest development in Bayinbuluk is low temperature and drought in winter.(3) The contents of organic matter,total nitrogen and total phosphorus in the timberline ecotones of Ili and Manas are higher than in other timberline ecotones.The Fukang timberline is the turning point of soil acidity and alkalinity,westwards soil is acid and eastwards is alkaline.Soil nutrients mainly exist in the surface layer(0—10 cm),low and no significant difference in the deep layer(30—80 cm),showing significant surface-convergence phenomenon.The change of pH value of deep soil from west to east is from weak acid to weak alkaline.The spatial variability of electric conductivity is significant,but there is no distinct difference among different layers.
Massimo Frezzotti - One of the best experts on this subject based on the ideXlab platform.
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a review of antarctic surface snow isotopic composition observations atmospheric circulation and isotopic modeling
Journal of Climate, 2008Co-Authors: Valerie Massondelmotte, Alexey Ekaykin, J Jouzel, Alberto J Aristarain, Ronaldo Torma Bernardo, David H Bromwich, O Cattani, M Delmotte, S Falourd, Massimo FrezzottiAbstract:A database of surface Antarctic snow isotopic composition is constructed using available measurements, with an estimate of data quality and local variability. Although more than 1000 locations are documented, the spatial coverage remains uneven with a majority of sites located in specific areas of East Antarctica. The database is used to analyze the spatial variations in snow isotopic composition with respect to Geographical Characteristics (elevation, distance to the coast) and climatic features (temperature, accumulation) and with a focus on deuterium excess. The capacity of theoretical isotopic, regional, and general circulation atmospheric models (including “isotopic” models) to reproduce the observed features and assess the role of moisture advection in spatial deuterium excess fluctuations is analyzed.