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941.
Xiang Qin ChuanJin Li CunDe Xiao ShuGui Hou MingHu Ding JiaWen Ren DaHe Qin 《中国科学:地球科学(英文版)》2014,57(10):2366-2373
This study investigates the regional distribution of marine aerosol originated species(Na+, Cl-, nss-SO42- and MSA) in the snow pits(or firn cores) collected along a transect between Zhongshan Station and the Grove Mountain area(450 km inland) on the eastern side of the Lambert Glacier Basin. Concentrations of Na+ and Cl- decrease exponentially with distance from the coast to 100 km inland(i.e., 1500 m a.s.l.). Statistical results demonstrate that distance from the coast inland and elevation affect the concentration of sea-salt originated ions in inland areas significantly. Increase of Cl-/Na+ ratio and higher variability in its standard deviation suggest that there are other sources of ions in addition to sea-salt in inland areas of the Antarctic continent. The concentrations of Na+ and Cl- from nine sampling sites in the Grove Mountain area are relatively higher than those from sites along CHINARE transect, although all sites are at similar distance inland. This phenomenon indicates that the barrier effect of the mountain may be the most important factor influencing ion deposition. In addition, nss-SO42- and MSA vary differently, with nss-SO42- decreasing with distance more significantly. This implies that sources and transporting pathways influence the deposition of the two sulfur compounds considerably, being supported by the spatial pattern of correlation coefficients between the nss-SO42- and MSA. 相似文献
942.
943.
Emergency evacuation in high-rise buildings is a crucial problem. The evacuation strategy of using stairs and evacuation elevators should be optimized. In this paper, simulation-based optimization method is used to optimize the evacuation strategy of using stairs and elevators in high-rise buildings. The stair simulation is based on a cellular automata model, and several typical pedestrians’ walk preferences are considered in this model. In the simulation, evacuation elevators can arrive at the refuge floors, and the scheduling of the elevators is optimized based on the GA algorithm. The simulation-based optimization is designed as a two-level problem: The upper level is a strategy level; the lower level is an operation level. In the study case, the evacuation strategy of a 100-floor ultra-high-rise office building is optimized. We find that if evacuees follow the traditional stair evacuation strategy, the evacuation time is 42.6 min. After optimization, the evacuation time of optimal strategy by using both stairs and elevators is 25.1 min. Compared with the traditional stair evacuation strategy, the efficiency of evacuation is improved by 41.1%. It is also found that the merging behavior in stairwells will decrease the velocity of the pedestrian flow. Stairs are still the main egress, and evacuation elevators are an assistant egress during high-rise building evacuation. 相似文献
944.
Natural Hazards - After the 2008 Wenchuan earthquake, secondary geological disasters occurred frequently and caused huge economic losses in the upper reaches of Min River. In this paper,... 相似文献
945.
High-speed landslide is a catastrophic geological disaster in the mountainous area of southwest China. To predict the movement process of landslide reactivation in Chenjiaba town, Beichuan county, Sichuan province, China, we simulated the movement process of two landslide failures in Chenjiaba via rapid mass movement simulation and unmanned aerial vehicle images(UAV), and obtained the movement characteristic parameters of the landslides. According to a back analysis, the most remarkable fitting rheological parameters were friction coefficient(μ=0.18) and turbulence(). The parameter of landslide pressure was applied as the zoning index of landslide hazard to obtain the influence zone and hazard zoning map of the Chenjiaba landslide. Results show that the Duba River was blocked quickly with a landslide accumulation at the maximum height of 44.14 mwhen the Chenjiaba deposits lost stability. The hazard zoning map indicated that the landslide hazard degree is positively correlated with the slope.This landslide assessment is a quantitative hazard assessment method based on a landslide movement process and is suitable for high-speed landslide. Such method can provide a scientific basis for urban construction and planning in the landslide hazard area to avoid hazards effectively. 相似文献
946.
947.
在同时考虑薄盘吸积与BlandfordZnajek过程的条件下讨论了黑洞吸积盘的的演化,并指出黑洞的无量纲角动量a是标志黑洞吸积盘演化特征的重要参量.得到描述黑洞自转的3个特征值:(1)aI≈0.983标志在薄盘吸积与BlandfordZnajek能量提取机制的作用下,中心黑洞的无量纲角动量a演化的上限;(2)aII≈0.940对应于黑洞薄盘内边缘半径rms演化的极小值;(3)aIII≈0.824对应于活动星系核射电噪度(radioloudnes)的极大值 相似文献
948.
Ruifeng Ding 《International journal of geographical information science》2018,32(8):1631-1648
How to exploit various features of users and points of interest (POIs) for accurate POI recommendation is important in location-based social networks (LBSNs). In this paper, a novel POI recommendation framework, named RecNet, is proposed, which is developed based on a deep neural network (DNN) to incorporate various features in LBSNs and learn their joint influence on user behavior. More specifically, co-visiting, geographical and categorical influences in LBSNs are exploited to alleviate the data sparsity issue in POI recommendation and are converted to feature vector representations of POIs and users via feature embedding. Moreover, the embedded POIs and users are fed into a DNN pairwise to adaptively learn high-order interactions between features. Our method is evaluated on two publicly available LBSNs datasets and experimental results show that RecNet outperforms state-of-the-art algorithms for POI recommendation. 相似文献
949.
950.
WU Jinkui DING Yongjian WANG Genxu SHEN Yongping Yusuke YAMAZAKI Jumpei KUBOTA 《中国地理科学(英文版)》2006,16(3):243-248
1 Introduction Most of the solar radiation that ecosystem seizes is con- sumed on latent, sensible and soil heat flux. Among them, latent heat flux shares the biggest part (Gutierrez and Meizer, 1994; Ham et al., 1991; Rachidi et al., 1993). The radiation budget and the energy balance are crucial to water conversion and effective water utilization. Also, they are important parts of research of water-saving ag- riculture (Mo et al., 1997). At present, the researches on radiation budget and e… 相似文献