Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： Forest surface combustibles are one of the important factors in forest fire propagation, and theircalorific values are an important index by which to assess combustibility. This study has aimed to assess thesurface fuels available in four typical vegetation types in the eastern Tianshan Mountains of Xinjiang, China. Thecharacteristics of the surface fuel calorific values and relationship with ignition point and absolute moisturecontent were analyzed. The results show that in coniferous and broad- leaved forests, there were significantdifferences between herb and litter components, while in shrub forest, there were significant differences betweenshrub and litter components. Within the same forest the calorific values were litter > herb > shrub > humus. Thecalorific values in the coniferous forests were the highest among the herbaceous fuel components (19.38 ± 0.08kJ·g−1), while those in the coniferous forests were highest among the litter fuel components (19.55 ± 0.05 kJ·g−1).Differences were identified in the relationship between the calorific value and the ignition point of the surfacecombustibles for the different components. There was a significant correlation between the burning point of theshrub fuel components and the calorific value (R2 = 0.81, P < 0.01), and between the burning point of litter fuelcomponents and the calorific value (R2 = 0.38, P < 0.05). However, there was no significant correlation betweenthe burning point and calorific value of the herbs and humus (P > 0.05). In addition, there was no significantcorrelation between the calorific values of the surface fuel and the absolute moisture content of all forest types.Forest type, tree species, physical and chemical properties, and other conditions were thus found to have acomprehensive effect on the calorific values of the different fuels. The results of this study provide a theoreticalbasis for forest fire management in the eastern Tianshan Mountains as they will help to accurately predict thecalorific energy and potential forest fire risks and provide data support for in-depth research on regional surfacefuels.
Subjects: Library Science，Information Science >> Information Science submitted time 2017-10-11 Cooperative journals: 《数据分析与知识发现》
Abstract： [Objective] This research aims to identify shopping tasks from product search, and then analyze the characteristic of multi-task sessions. [Methods] Using the product classification of Taobao, and a list of manually selected product terms, we identified online shopping tasks based on query terms from 19 704 search sessions by 2 754 users. [Results] First, factors influence the number of queries per shopping task: product characteristics, the amount of available products, and the difficulty in describing product category with query terms. Second, we found that in sessions with a major task, the relationship among the shopping tasks is closer. [Limitations] The task identification method based on query terms cannot completely describe the complex consumer shopping behaviors. [Conclusions] This study provides an exploratory understanding of the relationships among various shopping tasks, and may be used to improve product recommendation algorithm, as well as predict shopping behaviors.
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