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Analysis of the Spatial and Temporal Characteristics of Extreme Precipitation Events in Liaoning Province 被引量:5
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作者 王震 王颖 《Meteorological and Environmental Research》 CAS 2010年第10期39-42,共4页
Daily precipitation amounts from 1961 to 2005 in 35 observation stations in Liaoning Province were selected in order to study the temporal and spatial distribution of extreme precipitation events.By dint of EOF,REOF,m... Daily precipitation amounts from 1961 to 2005 in 35 observation stations in Liaoning Province were selected in order to study the temporal and spatial distribution of extreme precipitation events.By dint of EOF,REOF,mean-square-error and other ways,the changes in different regions of extreme precipitation and distribution were reflected.The analysis showed that,extreme precipitation in Liaoning Province could be divided into three areas,which were western Liaoning mountains and parts of northern areas,eastern Liaoning mountainous,near-coastal areas of Liaohe River Plain.In the relatively large precipitation areas,extreme precipitation threshold was also higher,and vice versa.The lower frequency of extreme precipitation events had a greater contribution to total precipitation;extreme precipitation,total precipitation and total rain days had the greatest changes in the summer,and the least changes in the winter;number of days of extreme precipitation changes in each season were not great;the change of extreme precipitation was not obvious in the long term. 展开更多
关键词 Extreme precipitation event spatial and temporal characteristic Twiddle factor Liaoning Province China
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Spatial-temporal Variation of Extreme Precipitation Events in Northwest China During 1961-2010 被引量:5
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作者 Lian Lishu Xu Shujing +1 位作者 Li Zhifu Sun Xiaoyin 《Meteorological and Environmental Research》 CAS 2014年第1期12-19,23,共9页
Using the daily precipitation data of 118 meteorological stations in Northwest China from January 1, 1961 to December 31,2010, we analyzed extreme precipitation events from prime precipitation data by applying R-langu... Using the daily precipitation data of 118 meteorological stations in Northwest China from January 1, 1961 to December 31,2010, we analyzed extreme precipitation events from prime precipitation data by applying R-language Climate Index (RClimDex). The spatial-temporal change characteristics in the past 50 years have been examined using the method of trend analysis, Mann-Kendall and the spatial analysis module of Arcgis9.2. The results show that the spatial distribution of the indices for extreme precipitation in Northwest China is greatly influenced by geographic location, atmospheric circulation and topography, and the spatial difference of extreme precipitation events is very evident, while the indices reduce from the southeast to the northwest except Consecutive Dry Days (CDD). In Xinjiang region, high values appear in Tianshan Mountains and decrease towards the south and north respectively. In the past 50 years, the temporal variation tendency of the indices for extreme precipitation in Northwest China has a great spatial distinction. It shows that the variation tendency is opposite between the east (decrease) and the west (increase), and CDD has a decreasing tendency while other indices increase. For each region, it is found that the indices for extreme precipitation in Xinjiang and Qinghai Province shows an increasing trend, and it is remarkable in Tianshan Mountains, the north of Xinjiang and the northeast of Qinghai Province. The temporal variation tendency of the indices for extreme precipitation in Ningxia, Shaanxi and Gansu has a large spatial distinction. The stations which have an increasing tend are mainly found in the north of Ningxia, south of Shaanxi and Hexi Corridor of Gansu. However, the south of Ningxia, north of Shaanxi and Longnan of Gansu Province mainly present a decreasing trend. The temporal variation tendency of the indices for extreme precipitation in Inner Mongolia is not obvious. Overall, the east part of Northwest China has a dry tendency, while the west part has an opposite trend. 展开更多
关键词 Northwest China Extreme precipitation events spatial-temporal variation characteristics Mann-Kendall method China
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Spatial and Temporal Variations of Extreme Climate Events in Xinjiang, China during 1961-2010 被引量:6
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作者 Xiangling Tang Xin Lv Yineng Ouyang 《American Journal of Climate Change》 2016年第3期360-372,共14页
Daily maximum/minimum temperature and precipitation data from 35 weather stations in Xinjiang during 1961-2010 were examined using kriging spatial analysis, linear tendency estimation, and correlation analysis. Tempor... Daily maximum/minimum temperature and precipitation data from 35 weather stations in Xinjiang during 1961-2010 were examined using kriging spatial analysis, linear tendency estimation, and correlation analysis. Temporal trends and spatial distribution patterns of extreme temperature and precipitation in this area were then analyzed using 12 extreme temperature and 7 extreme precipitation indices. The following results were obtained. 1) Over the past 50 years, extreme cold indices, excepting the monthly maximum temperature minimum value and monthly extreme minimum temperature, showed slight decreasing trends. These indices include the maximum number of consecutive frost days, icy days, cold-nighttime days, and cold-daytime days. 2) Extreme warm events generally showed significant increasing trends (P < 0.01), including the indices of summertime days, warm-nighttime days, warm-daytime days, monthly extreme maximum temperature, and monthly minimum temperature maximum value. 3) The spatial distributions of threshold values of extreme warm and cold events showed notable regional differences. A reducing trend of extreme cold events and an increase in extreme warm events has occurred mainly in northern Xinjiang. 4) For the past 50 years, six extreme precipitation indices, aside from consecutive dry days, showed significant increasing trends in Xinjiang (P < 0.05) and notable differences in spatial distribution. The increase in extreme precipitation events was more rapid at northern than at southern sites. Extreme precipitation intensity was greater in mountainous areas, and precipitation frequency increased in the plain region. 5) Factor analysis revealed good correlations among extreme temperature indices, excepting extreme temperature days. 展开更多
关键词 Xinjiang Area Extreme Climatic event spatial Change
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Effect of Neurofeedback on Visual-Spatial Attention in Male Children with Reading Disabilities: An Event-Related Potential Study
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作者 Neda Sadeghi Mohammad Ali Nazari 《Neuroscience & Medicine》 2015年第2期71-79,共9页
Recent studies describe a number of difficulties associated with attention deficit in children with reading disabilities. Information about visual-spatial attention mainly arises from studies using event-related poten... Recent studies describe a number of difficulties associated with attention deficit in children with reading disabilities. Information about visual-spatial attention mainly arises from studies using event-related potentials (ERPs) during Posner’s spatial cueing paradigm. This study aims to use neurofeedback with a special protocol for treating children with reading disabilities, and moreo-ver, to evaluate visual-spatial attention ability by means of Posner paradigm task and ERPs. The study was conducted in a single subject design in 20 sessions. Participants were 2 male children, aged between 10 - 12 years old, who completed twelve 30-min neurofeedback sessions. Repeated measurements were performed during the baseline, treatment, and post treatment phases. Results showed some improvement in Posner paradigm parameters (correct response, valid and invalid reaction times). Furthermore, grand average ERPs for both of the participants in each of the four conditions (Valid-right, Invalid-right, Valid-left and Invalid-left) were analyzed. The analysis of P3 component showed a reduction in latency, indicating an improvement in the timing of cognitive processes. In addition, the graphs showed a decrease in amplitude level, which meant easier processing than before. 展开更多
关键词 NEUROFEEDBACK READING DISABILITY Visual-spatial Attention ERP event-RELATED POTENTIALS
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Analysis on Spatial and Temporal Changes of Extreme Precipitation Events in Ningxia in Recent 50 Years
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作者 LI Xin ZHENG Guang-fen +1 位作者 NA Li WANG Su-yan 《Meteorological and Environmental Research》 2012年第6期22-25,29,共5页
[ Objective] The aim was to study the spatial and temporal changes of extreme precipitation events in Ningxia in recent 50 years. [ Method] Using dally precipitation data at 20 stations in Ningxia from 1961 to 2010, a... [ Objective] The aim was to study the spatial and temporal changes of extreme precipitation events in Ningxia in recent 50 years. [ Method] Using dally precipitation data at 20 stations in Ningxia from 1961 to 2010, and defining the threshold value of extreme precipitation in each sta- tion by percentage method, choosing indicators such as precipitation, frequency and intensity of extreme precipitation events, the characteristics of the spatial and temporal distribution and linear trend of extreme precipitation events in Ningxia were analyzed based on linear regression and M-K non-parameter statistical test method. [ Result] The percentage method suggested the threshold value of average extreme precipitation in Ningxia in recent 50 years decreased from south to north. The large threshold value was in southern Haiyuan, Tongxin and northern Yancheng, which was similar to the distribution of mean annual precipitation in Ningxia. In recent 50 years, extreme precipitation frequency and extreme precipitation de- creased in most part of Ningxia but the intensity tended to strengthen. Study of extreme precipitation in Mahuang Mountain and Liupan Mountain in- dicated that precipitation frequency, intensity and extreme precipitation reduced. Annual extreme precipitation frequency narrowed and then in- creased after 1994 and had mutation in 2003. Annual extreme precipitation intensity enhanced since 1984. Mutation took place in 1984. Intensity in Liupan Mountain had weakened since 1978. [ Conclusion] The study provided theoretical basis for the mutation of climate in Ningxia. 展开更多
关键词 Extreme precipitation events spatial and temporal changes Ningxia China
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THE TEMPORAL AND SPATIAL PATTERNS OF ENVIRONMENTAL RISK EVENTS IN THE PAST 30 YEARS IN SHENYANG CITY
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作者 Bi Jun Tang Yijian Zhang Shen(Institute of Geography, CAS, Beijing 100101People’s Republic of China)Wang Huadong(Institute of Environmental Sciences, Beijing Normal University, Beijing 100875People’s Republic of China) 《Journal of Geographical Sciences》 SCIE CSCD 1995年第1期76-86,共11页
The index of Risk Frequency (RF) and other relative indices are used to analyze the temporal and spatial patterns of environmental riskevents in the past 30 years in Shenyang city. The results show that thereexists si... The index of Risk Frequency (RF) and other relative indices are used to analyze the temporal and spatial patterns of environmental riskevents in the past 30 years in Shenyang city. The results show that thereexists significant difference of the RFs between periods of 1966-1977 and1978-1991 (t=7.353**, t0.01=2.807). During the past 30 years, there areno significant changes of the spatial patterns of the environmental risk,while the proportions of environmental risk among the districts are extremely different. In Shenyang city, there exists a series of high riskenterprises, and the chemical industry is the one with highest risk. 展开更多
关键词 environmental risk events temporal and spatial patterns risk frequency
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Study on Temporal-spatial Change Characteristics of the Extremely Low Temperature Climate Event in Winter of China
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作者 Zhonghong Luo Hangdong Jiang +1 位作者 Jiangyong Pan Jiayou Huang 《Meteorological and Environmental Research》 CAS 2013年第4期10-13,16,共5页
[ Objective] The research aimed to study temporal-spatial change characteristics of the extremely low temperature climate event in winter of China. [MethodI By using actual probability distribution threshold value met... [ Objective] The research aimed to study temporal-spatial change characteristics of the extremely low temperature climate event in winter of China. [MethodI By using actual probability distribution threshold value method, EOF analysis method and the daily minimum temperature data in winter of 1961 -2008 at 195 observatories of China, temporal-spatial change characteristics of the extremely low temperature climate event in win- ter of China in 48 years were analyzed. [ Result] Threshold value calculated by actual probability distribution was higher than that by traditional method, and increase magnitude in east was bigger than that in west, which could describe climatic change situation in China in 48 years better than traditional method. Cold night number in winter of China did not decrease as latitude declined, and it was more in south and north and was less in Yellow River basin and northwest China. Cold night number was the most in northeast Inner Mongolia. Interannual change of the cold night number presented decline tendency. From the 1960s to the eady 1970s, cold night number consistently increased, and change in middle and late periods of the 1960s was severe. From the early 1970s to the middle 1980s, fluctuation of the cold night number was bigger, and increase of the cold night number was the most in 1976. Cold night number from 1986 to the 21= century continuously declined. Change of the cold night number was the most obvious in east region, Guizhou and north Guangxi. Cold night number in northeast China and north Inner Mongolia presented inverting change relationship with that in Yunnan - Kweichow Plateau and Hexi Corridor. [ Conclusion] The research provided reference for eady warning of the extremely low temoerature event in China. 展开更多
关键词 Minimum temperature Extremely low temperature event Cold night Temporal-spatial change characteristics China
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Spatial Analysis of Affected Areas by Extreme Hydrological Events in Rio de Janeiro (The Host City for the 2016 Olympic Games)—Brazil
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作者 Leandro Andrei Beser de Deus Camilla Silva Motta Santos +2 位作者 Patricia Gomes da Silveira Marcos Aurélio Vasconcelos Freitas Paulo Márcio Leal Menezes 《Journal of Geographic Information System》 2013年第4期337-346,共10页
The most frequent types of disasters in Brazil are associated with extreme hydrological events. Adding to this situation, in Brazil, there are the extreme sociospatial discrepancies that are historically constructed. ... The most frequent types of disasters in Brazil are associated with extreme hydrological events. Adding to this situation, in Brazil, there are the extreme sociospatial discrepancies that are historically constructed. They leave marks in space, making specific areas, for political interest or not, more vulnerable to the different mentioned processes. To this extent, the public management should plan actions and, also, it may act in a more holistic way adding new trends, such as, the use of geotechnologies that are applied to environmental management in the realm of urban planning. From a case study in the city of Rio de Janeiro, this paper aims to contribute and draw attention to such issues. It may reach its target through pointing and spatially analyzing which areas are in the most critical situation related to the occurrence of extreme hydrological events. To achieve this goal, it was proposed a methodology to inventory the occurrence of inundation/flooding for a certain period, in this case 2001-2008. Besides, the methodology could systematize data and integrate them with other important issues for supporting the process of identification and analysis of the most critical areas. Historical aspects of occupation and the most vulnerable socio-environmental aspects were raised, too, in order to validate the highlighted areas. This integration was enabled concerning the support of geoprocessing techniques. The results of this integration subsidized the mapping and spatial analysis of the affected areas in the city and the criticality in relation to the extreme hydrological events. Finally, it was possible to observe that the identification of the most critical affected areas does not mean the exhaustion of the subject. The location of these areas is directly linked to the sample that was used as the basis for analyses. This data set only represents recorded events by the Municipal Civil Defense respecting the studied time frame. However, the results permit to take notes and raise relevant environmental questions about the roots and the occurred impacts that were originated from the extreme hydrological events, which have been observed in recent decades. 展开更多
关键词 EXTREME eventS FLOOD Hazards GIS Hydric RESOURCES spatial Analysis
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Spatial trends of dustfall over northern China in the spring and their influencing factors 被引量:1
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作者 JinChang Li ZhiBao Dong +1 位作者 GuangQiang Qian WanYin Luo 《Research in Cold and Arid Regions》 2010年第6期529-537,共9页
The spatial trends of dustfall of different sizes over northern China during April and May 2001,and March 2002,and their influencing factors,were analyzed.We divided the dustfall into seven grades based on particle si... The spatial trends of dustfall of different sizes over northern China during April and May 2001,and March 2002,and their influencing factors,were analyzed.We divided the dustfall into seven grades based on particle size.Total dustfall and dustfall for each grade were highest in desert regions then in regions undergoing desertification,and the total dustfall,dustfall 【100 μm and dustfall 】250 μm were higher in western agricultural regions closer to desert areas than in eastern agricultural regions.The spatial trends in dustfall 【300 μm in diameter were most strongly correlated with dust events,and the content of coarse particles increased with increasing severity of dust events.Because the spatial trend for dust events appears to be controlled by geomorphic conditions,vegetation coverage,soil moisture,and the distance from dust source,dustfall 【300 μm in diameter appears to have the same controlling factors as dust events,but the control decreases with increasing particle size.Wind,the driving force for dust emissions,also influenced the spatial trends in dustfall 【200 μm in diameter,and especially for dustfall 50 to 100 μm in diameter.Although dustfall 【300 μm in diameter and precipitation were not strongly spatially correlated,there is some evidence that high precipitation decreased deposition by restraining blowing sand.The coarser the dustfall,the weaker the correlation with wind speed;however,transport of larger particles still occurs,and further research will be required to test the possibility that this dust is entrained mainly by the small-scale dust devils that are commonly observed in the study area. 展开更多
关键词 DUSTFALL DESERTIFICATION spatial trends dust events geomorphic conditions Northern China
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Rule-and PSO Algorithm-based Dynamic Spatial Rescheduling Method for Hull Curved Block Construction 被引量:2
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作者 ZHANG Zhiying GU Jiayu +1 位作者 XU Chen LI Zhen 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2013年第3期594-605,共12页
Due to no effective rescheduling method in hull curved block construction planning, existing scheduling planning can’t be applied in practical production effectively. Two-dimensional layout and dynamic attributes of ... Due to no effective rescheduling method in hull curved block construction planning, existing scheduling planning can’t be applied in practical production effectively. Two-dimensional layout and dynamic attributes of block construction planning are considered to develop a spatial rescheduling method, which is based on the spatial points searching rule and the particle swarm optimization(PSO) algorithm. A dynamic spatial rescheduling method is proposed to solve the manufacturing problem of rush-order blocks. Through spatial rescheduling, the rescheduling start time, the current processing information set and rescheduling blocks set can be obtained automatically. By using and updating the data of these sets, the rescheduling method combines the PSO algorithm with the spatial points searching rule to determine the rescheduling start time and layout of the blocks. Three types of dynamic events, including rush-order block delay, existing block delay and existing block position changes, are used to address problems with different function goals by setting different function weights. Finally, simulations based on three types of rush-order block events are performed to validate this method, including single rush-order block, multi rush-order blocks at the same time and multi rush-order blocks at different times. The simulation results demonstrate that this method can solve the rush-order block problems in hull block construction and reduce the interference to the existing manufacturing schedule. The proposed research provides a new rescheduling method and helps instruct scheduler to make production planning in hull block construction. 展开更多
关键词 spatial scheduling rush-order block event particle swarm optimization dynamic rescheduling
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Modeling Spatial Opportunity Structures and Youths’ Transitions from School to Training
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作者 Alexandra Wicht Alexandra Nonnenmacher 《Open Journal of Statistics》 2017年第6期1013-1038,共26页
This paper examines the significance of spatial externalities for youths’ school-to-training transitions in Germany. For this purpose, it is necessary to address the methodological question of how an individual’s sp... This paper examines the significance of spatial externalities for youths’ school-to-training transitions in Germany. For this purpose, it is necessary to address the methodological question of how an individual’s spatial context has to be operationalized with respect to both its extent and the problem of spatial autocorrelation. Our analyses show that the “zone of influence” comprises of the whole of Germany, not only close-by districts, and that these effects differ between structurally weak and strong regions. Consequently, assuming that only close proximity affects individual outcomes may disregard relevant contextual influences, and for spatial models that require an a priori definition of the weights for spatial units, it may be erroneous to make a decision based on this assumption. Concerning spatial autocorrelation, we found that neglecting local spatial autocorrelation at the context level causes considerable bias to the estimates, especially for districts that are close to the home district. 展开更多
关键词 spatial Effects spatial Autocorrelation event History Models YOUTHS School-to-Work TRANSITIONS OPPORTUNITY STRUCTURES
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“23.7”华北特大暴雨过程小时强降水时空分布特征 被引量:1
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作者 唐永兰 徐桂荣 +2 位作者 唐国瑛 张文 闵爱荣 《大气科学学报》 CSCD 北大核心 2024年第5期778-788,共11页
由于西北太平洋副热带高压、2023年第5号台风“杜苏芮”、第6号台风“卡努”等共同作用,2023年7月29日08时—8月2日08时(北京时)华北地区发生极端特大暴雨,造成了重大社会影响。利用中国气象局国家气象信息中心提供的国家级气象站逐小... 由于西北太平洋副热带高压、2023年第5号台风“杜苏芮”、第6号台风“卡努”等共同作用,2023年7月29日08时—8月2日08时(北京时)华北地区发生极端特大暴雨,造成了重大社会影响。利用中国气象局国家气象信息中心提供的国家级气象站逐小时降水资料,分析了此次特大暴雨过程中的小时强降水(Hourly Heavy Rainfall,HHR)时空分布特征,并对不同历时类型强降水事件(Heavy Rainfall Event,HRE)的统计特征进行了对比。结果表明:1)此次特大暴雨HHR强度高、局地性明显,其对总降水量的贡献超过20%,北京西部、河北中部和西南部等太行山东麓为HHR降水量大值区和降水频次活跃区,双台风将水汽源源不断地输送到华北平原,受到太行山等山脉阻挡抬升,利于HHR增幅和持续。2)HHR降水量、降水频次经历6次峰值后减弱,其中第3次峰值时段的HHR降水量最大、降水频次最多、持续时间最长;而在“杜苏芮”残涡螺旋影响、暖式切变线和偏东风影响以及偏南或西南急流影响的3个主要降水阶段中,“杜苏芮”残涡螺旋影响阶段HHR最为活跃,共发生257次HHR,HHR最大降水量达73.5 mm。3)在3种类型HRE中,长历时(>12 h)最多,占比54.5%,短历时(1~6 h)次之,占比32.9%,中历时(7~12 h)最少,占比12.6%;长历时HRE降水量多>180 mm,短历时、中历时HRE的降水量多为[20,60)mm;HRE的最大降水量表现为短历时<中历时<长历时,而最大降水强度表现正相反,3种历时HRE的最大小时降水量多为[20,30)mm。4)不同类型HRE降水量、频次和平均降水强度的空间分布显示,长历时HRE因频次高于短历时和中历时,加之历时长,其降水量也高于后两种类型,北京、河北等地是长历时HRE降水量和频次大值区。 展开更多
关键词 华北 特大暴雨 小时强降水 强降水事件 时空分布 台风 地形
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针对室内火灾应急响应的空间关键字查询方法研究
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作者 张丽平 李春红 李松 《中国安全生产科学技术》 CAS CSCD 北大核心 2024年第11期118-123,共6页
为提高室内火灾应急响应的效率,提出1种针对室内火灾应急响应的空间关键字查询方法。首先,引入1种新的索引结构,即室内火灾应急响应树(IFER-tree)来提高对室内空间关键字的检索速度;其次,提出基于IFER-tree的剪枝方法,对数据集进行有效... 为提高室内火灾应急响应的效率,提出1种针对室内火灾应急响应的空间关键字查询方法。首先,引入1种新的索引结构,即室内火灾应急响应树(IFER-tree)来提高对室内空间关键字的检索速度;其次,提出基于IFER-tree的剪枝方法,对数据集进行有效地精炼,减少对查询时间和计算资源的消耗;最后,提出1种针对室内火灾应急响应的路径查询方法,以便迅速识别出考虑危险程度的最短逃生路径。研究结果表明:所提出的空间关键字查询方法能快速查询到最优路径,提高火灾应急响应效率。研究结果可为火灾紧急情况下的人员疏散提供重要参考,尤其在确定最优逃生路径和评估危险程度方面,能够有效减少人员伤亡。 展开更多
关键词 查询 紧急事件响应 室内空间关键字索引 应急响应
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Identifying the Spatial Structure of Black Hole and Tropical Cyclone Based on a Theoretical Analysis of Orthogonal Interaction
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作者 Weihong Qian 《Journal of Modern Physics》 CAS 2023年第6期933-952,共20页
Black holes are recognized by Newton’s gravitational theory and Einstein’s general relativity, but there is still a lack of understanding the spatial structure of events, especially the nature of event horizon. In t... Black holes are recognized by Newton’s gravitational theory and Einstein’s general relativity, but there is still a lack of understanding the spatial structure of events, especially the nature of event horizon. In this paper, a theoretical analysis is used to compare the structures of tropical cyclone in the atmosphere and black hole in the astronomy so that five results are: 1) Both of them share the similar spatial structure, with tropical cyclone and black hole having the outflow cloud shield and the horizon sphere in the central part, respectively, while four spiral material bands exist in the rotating plane around them;2) In theoretically, the energy density formed by the orthogonal interaction of the four spiral material bands is as times as the total kinetic energy of the head-on interaction;3) This region of high energy density can lead to the conversion from mass to energy and the creation of new physical states of matter, which is a black hole event;4) The outer horizon of a black hole is the outermost interface of events, or the orthogonal interaction interface of particles;5) High-speed plasma jets extended at the poles of the black hole are directly associated with the shear stress of orthogonal interaction. 展开更多
关键词 Black Hole event Horizon Tropical Cyclone spatial Structure Orthographic Interaction
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INVESTIGATION OF THE SPATIAL AND TEMPORAL DISTRIBUTION OF EXTREME HIGH TEMPERATURE IN CHINA WITH DETRENDED FLUCTUATION AND PERMUTATION ENTROPY
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作者 尹继福 郑有飞 +2 位作者 吴荣军 傅颖 王维 《Journal of Tropical Meteorology》 SCIE 2013年第4期349-356,共8页
With temperatures increasing as a result of global warming,extreme high temperatures are becoming more intense and more frequent on larger scale during summer in China.In recent years,a variety of researches have exam... With temperatures increasing as a result of global warming,extreme high temperatures are becoming more intense and more frequent on larger scale during summer in China.In recent years,a variety of researches have examined the high temperature distribution in China.However,it hardly considers the variation of temperature data and systems when defining the threshold of extreme high temperature.In order to discern the spatio-temporal distribution of extreme heat in China,we examined the daily maximum temperature data of 83 observation stations in China from 1950 to 2008.The objective of this study was to understand the distribution characteristics of extreme high temperature events defined by Detrended Fluctuation Analysis(DFA).The statistical methods of Permutation Entropy(PE)were also used in this study to analyze the temporal distribution.The results showed that the frequency of extreme high temperature events in China presented 3 periods of 7,10—13 and 16—20 years,respectively.The abrupt changes generally happened in the 1960s,the end of 1970s and early 1980s.It was also found that the maximum frequency occurred in the early 1950s,and the frequency decreased sharply until the late 1980s when an evidently increasing trend emerged.Furthermore,the annual averaged frequency of extreme high temperature events reveals a decreasing-increasing-decreasing trend from southwest to northeast China,but an increasing-decreasing trend from southeast to northwest China.And the frequency was higher in southern region than that in northern region.Besides,the maximum and minimum of frequencies were relatively concentrated spatially.Our results also shed light on the reasons for the periods and abrupt changes of the frequency of extreme high temperature events in China. 展开更多
关键词 EXTREME high temperature eventS detrended FLUCTUATION analysis PERMUTATION ENTROPY spatial and TEMPORAL distribution
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体育赛事、环境规制与城市环境治理效率——基于中国百强城市的实证研究 被引量:3
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作者 李军林 路嘉明 +1 位作者 王禹辰 李树旺 《天津体育学院学报》 CAS CSSCI 北大核心 2024年第3期258-266,共9页
大型体育赛事具有广泛的社会、经济影响力。如何利用举办体育赛事促进城市发展、改善生态环境是建设体育强国,促进体育事业高质量发展的重要一环。新时代以来,在绿色新发展理念的指导下,环保和可持续发展成为体育赛事的重要目标,地方政... 大型体育赛事具有广泛的社会、经济影响力。如何利用举办体育赛事促进城市发展、改善生态环境是建设体育强国,促进体育事业高质量发展的重要一环。新时代以来,在绿色新发展理念的指导下,环保和可持续发展成为体育赛事的重要目标,地方政府也因此以举办大型体育赛事为契机,提升环境规制水平,以期体育赛事成为推动城市绿色发展的动力之一。使用DEA-SBM模型测算我国百强城市的环境治理效率,并使用空间双重差分法分析我国百强城市2010—2019年申办的国家以上级别综合性体育赛事对城市环境治理、环境规制以及绿色创新的影响。结果表明,大型赛事的申办会显著提高举办城市的环境治理效率,该结果在控制城市产业结构、人力资本水平、工业行业规模、环境治理支出等有可能造成影响的变量后依然成立。通过机制检验发现,大型体育赛事能够通过提高举办地的环境规制强度和绿色创新强度两条路径提高环境治理效率。研究证明,中国的体育赛事已经成为积极、高效的环境治理方式之一,能够长期促进城市新质绿色生产力的发展。 展开更多
关键词 体育赛事 绿色创新 环境治理效率 空间DID 新质生产力
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抽象性位移事件及其汉语编码的认知阐释
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作者 张克定 《天津外国语大学学报》 2024年第5期10-19,111,共11页
作为认知主体的人不仅有能力识解出抽象性位移事件,而且有能力将其编码为特定的语言结构并用于交际。作为一种特殊的位移事件,抽象性位移事件的形成是有认知理据的,这一认知理据就是抽象实体的可动化机制。该机制有其自身的认知特性,其... 作为认知主体的人不仅有能力识解出抽象性位移事件,而且有能力将其编码为特定的语言结构并用于交际。作为一种特殊的位移事件,抽象性位移事件的形成是有认知理据的,这一认知理据就是抽象实体的可动化机制。该机制有其自身的认知特性,其使用会受到一定的条件限制。编码抽象性位移事件的语言表达式可以叫作抽象性空间位移关系构式。汉语抽象性空间位移关系构式的构成既要受到整体性限制条件的制约,又要受到局部性限制条件的制约。 展开更多
关键词 抽象性位移事件 编码 汉语抽象性空间位移关系构式 认知机制 限制条件
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基于混合神经网络和注意力机制的生物医学事件触发词识别方法
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作者 任永功 林禹竹 +2 位作者 唐玉洁 于博 何馨宇 《电子学报》 EI CAS CSCD 北大核心 2024年第9期3206-3216,共11页
生物医学事件作为生物医学文本挖掘的重要组成部分,在生物医学研究和疾病的预防中发挥着重要作用.触发词识别是生物医学事件抽取的关键和前提步骤,旨在提取描述事件类型的关键词.传统方法在特征提取过程中过分依赖自然语言处理工具,导... 生物医学事件作为生物医学文本挖掘的重要组成部分,在生物医学研究和疾病的预防中发挥着重要作用.触发词识别是生物医学事件抽取的关键和前提步骤,旨在提取描述事件类型的关键词.传统方法在特征提取过程中过分依赖自然语言处理工具,导致耗费人工成本.另外,由于生物医学文献的特殊性—长文本语句多,导致长距离依赖问题比较明显.为了解决这些问题,我们提出了一种混合结构,由残差卷积神经网络和双向长短期神经网络、混合神经网络和多头注意力机制组成.该模型利用残差卷积神经网络提取单词级特征并利用双向长短期神经网络提取上下文语义信息.此外,本文通过空间域滑动窗口将长句划分为等长短句,在不破坏上下文信息的前提下,避免了长距离依赖.实验结果表明,本文提出的方法在生物医学事件抽取通用语料MLEE(Multi-Level Event Extraction)上取得了较好的效果,F值达到81.15%. 展开更多
关键词 生物医学事件抽取 触发词识别 ReCNN-BiLSTM 空间域滑动窗口 MUH-Attention机制 混合神经网络
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松花江流域NPP时空演变及其对极端气候的响应机制 被引量:1
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作者 贾朝阳 郭亮 +2 位作者 崔嵩 付强 刘东 《南水北调与水利科技(中英文)》 CAS CSCD 北大核心 2024年第1期131-147,共17页
为探究全球气候变化条件下松花江流域陆地生态系统健康程度的变化特征,基于2000—2020年MODIS MOD17A3HGF数据集,采用趋势分析、相关性分析、M-K检验、地理探测器和相对重要性分析等方法,结合气象站点数据和土地利用数据,分析植被净初... 为探究全球气候变化条件下松花江流域陆地生态系统健康程度的变化特征,基于2000—2020年MODIS MOD17A3HGF数据集,采用趋势分析、相关性分析、M-K检验、地理探测器和相对重要性分析等方法,结合气象站点数据和土地利用数据,分析植被净初级生产力(net primary productivity,NPP)时空演变特征及其对极端气候事件的响应机制。结果表明:松花江流域年均NPP值为407.45 g/m^(2)(以C计,下同),以年均4.82 g/m的速率显著上升(p<0.01);极端降水事件对植被NPP空间分异性的影响强于极端气温事件,极端气候指数间交互作用的影响大于单一极端气候指数的影响,流域及农田和草地生态系统NPP主要受总降水量(PRCPTOT)与年平均最低气温(TMIN)交互作用的影响,森林、湿地和聚落生态系统NPP分别受中雨日数(R10 mm)与年平均最高气温(TMAX)交互作用、强降水量(R95P)与TMIN交互作用和R10 mm与暖夜日数(TN90P)交互作用的影响;时间尺度上PRCPTOT、TMAX和TMIN是植被NPP的主要影响因素,空间尺度上PRCPTOT和TMIN是多年平均NPP的主要影响因素。研究结果可为量化气候变化背景下区域生态系统健康程度和应对极端气候事件措施的制定提供科学依据。 展开更多
关键词 松花江流域 净初级生产力 极端气候事件 陆地生态系统 时空演变规律 驱动因素 地理探测器
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职业体育赛事对经济高质量发展的空间溢出效应
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作者 王志远 慈芳慧 钟声 《同济大学学报(社会科学版)》 CSSCI 北大核心 2024年第5期116-128,共13页
基于空间计量等方法对2004—2019年280个城市的面板数据进行研究可以发现:中国职业体育赛事可以显著促进经济高质量发展,且高等级联赛影响效应更大;中国职业体育赛事对经济高质量发展的影响呈现出空间溢出的特点,且在东、中、西部地区... 基于空间计量等方法对2004—2019年280个城市的面板数据进行研究可以发现:中国职业体育赛事可以显著促进经济高质量发展,且高等级联赛影响效应更大;中国职业体育赛事对经济高质量发展的影响呈现出空间溢出的特点,且在东、中、西部地区存在显著的区域异质性。以上结论在进行更换空间权重矩阵、构建动态空间杜宾模型等稳健性检验后仍然成立。这一结论为职业体育赛事对经济高质量发展的贡献提供了新的理论依据,可以深化我们对职业体育与经济高质量发展空间效应和地区差异的理解。 展开更多
关键词 职业体育赛事 体育产业 经济高质量发展 空间溢出效应 赛事经济
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