Through practical sampling survey for the overseas travelers in the 12 tourist hotspot cities of China, the analytical results of database of the spatial changes for overseas travelers have been established with the h...Through practical sampling survey for the overseas travelers in the 12 tourist hotspot cities of China, the analytical results of database of the spatial changes for overseas travelers have been established with the help of the software Visual FoxPro. The New concepts such as transferring state, which can be used to study the spatial flow intensity of travelers. is first put forward By analyzing the statistical results, the spatial flow intensity of 12 tourist hotspot cities in China for overseas travelers has been probed At last, a practical research of spatial flow intensity for overseas tourists is carried out in Beijing──the of tourist hotspots of China展开更多
Research on spatial flow as it relates to the relationship between the supply and demand of ecosystem services supports a significant connection between the supply of ecosystem services and human well-being.Understand...Research on spatial flow as it relates to the relationship between the supply and demand of ecosystem services supports a significant connection between the supply of ecosystem services and human well-being.Understanding the entire process of the production and flow,as well as the use of ecosystem services,accurately assessing the balance of supply and demand of ecosystem services,and establishing a two-way feedback relationship between supply and demand are vital for the scientific management of the ecosystem and ensuring the sustainable development of regional resources.Based on a large number of relevant publications,this paper comprehensively summarizes the concepts and assessment methods of ecosystem service supply and demand from the perspective of ecosystem service supply and demand,and discusses the impacts of land use and climate change on the temporal and spatial changes of ecosystem services under the background of global change.Then,an analysis of the research progress in the ecosystem services spatial flow indicated that there are still deficiencies in the quantification of cultural services,the dynamics of ecosystem service flow and the driving mechanism of ecosystem services.We also propose that clarifying the driving mechanism and transfer process of ecosystem services,and realizing the mutual conversion between different spatial-temporal scales of ecosystem services,is an important approach for improving the application of ecosystem services research in practice in the future.展开更多
This paper puts forward a novel concept, the spatial flow influence factor (SFIF), which provides a new insight into the airflow structure. This concept is very helpful in the control of indoor air pollutants since: (...This paper puts forward a novel concept, the spatial flow influence factor (SFIF), which provides a new insight into the airflow structure. This concept is very helpful in the control of indoor air pollutants since: (1) for a given indoor airflow; given sources of volatile organic compounds (VOCs), the optimal arrangement of the VOC sources can easily be obtained; (2) for given positions of VOC sources; occupied regions (or target regions), the optimal indoor airflow pattern or organization can be determined; (3) the SFIF for an indoor space can also be regarded as the indoor air safety index of that space. To illustrate this concept, we present several examples of applying a SFIF to indoor air VOC control.展开更多
Although water has the central function of the bloodstream in the biosphere especially in arid or semi-arid regions such as Yah＇an region in northwestern China, yet the very limited attention is paid to the role of t...Although water has the central function of the bloodstream in the biosphere especially in arid or semi-arid regions such as Yah＇an region in northwestern China, yet the very limited attention is paid to the role of the water-related processes in ecosystem. In this research, based on continuous nearly 50-year data including runoff volume, sediment discharge as well as sediment accretion from hydrographic stations, and 10-year information of water quality from pollution monitoring stations, the method for measuring in-stream flow requirement has been put forward supported by experiential models and GIS spatial analysis. Additionally, the changes of in-stream flow requirement for environment and economic development have been addressed from spatial-temporal dimensions. The results show that： （1） According to the central streams in Yan＇an region, mean annual in-stream flow requirement reaches 1.0619 billion m^3, and the surface water for economic exploitation is 0.2445 billion m3 （2） Mean annual in-stream flow requirement for sediment transfers in flood period occupies over 80% of the integrated volume in a year. （3） From the 1950s to 1970s, in-stream flow requirement for sediment transfers is comparatively higher, while from the 1980s to 1990s, this requirement presents a decreasing tendency.展开更多
Different from previous temporal evolution assumption, the spatially growing mode was employed to analyze the linear stability for the channel flow of fiber suspensions. The stability equation applicable to fiber susp...Different from previous temporal evolution assumption, the spatially growing mode was employed to analyze the linear stability for the channel flow of fiber suspensions. The stability equation applicable to fiber suspensions was established and solutions for a wide range of Reynolds number and angular frequency were given numerically . The results show that, the flow instability is governed by a parameter H which represents a ratio between the axial stretching resistance of fiber and the inertial force of the fluid. An increase of H leads to a raise of the critical Reynolds number, a decrease of corresponding wave number, a slowdown of the decreasing of phase velocity , a growth of the spatial attenuation rate and a diminishment of the peak value of disturbance velocity. Although the unstable region is reduced on the whole, long wave disturbances are susceptible to fibers.展开更多
In this study, we investigated the origin of the overland flow roughness problem and divided the current overland flow roughness research into three types, as follows: the first type of research takes into account the...In this study, we investigated the origin of the overland flow roughness problem and divided the current overland flow roughness research into three types, as follows: the first type of research takes into account the effects of roughness on the volume and velocity of surface runoff, flood peaks, and the scouring capability of flows, but has not addressed the spatial variability of roughness in detail; the second type of research considers that surface roughness varies spatially with different land usage types, land-cover conditions, and different tillage forms, but lacks a quantitative study of the spatial variability; and the third type of research simply deals with the spatial variability of roughness in each grid cell or land type. We present three shortcomings of the current overland flow roughness research, including(1) the neglect of roughness in distributed hydrological models when simulating the overland flow direction and distribution,(2) the lack of consideration of spatial variability of roughness in hydrological models, and(3) the failure to distinguish the roughness formulas in different overland flow regimes. To solve these problems,distributed hydrological model research should focus on four aspects in regard to overland flow: velocity field observations, flow regime mechanisms, a basic roughness theory, and scale problems.展开更多
The study was designed to investigate temporal and spatial seasonal variations in quality properties of gravity flow water samples collected from Kigata, Kacuro, Kihanga, Kitibya and Kanjobe located in Kyanamira Sub-C...The study was designed to investigate temporal and spatial seasonal variations in quality properties of gravity flow water samples collected from Kigata, Kacuro, Kihanga, Kitibya and Kanjobe located in Kyanamira Sub-County, Kabale District, Uganda. Physical, chemical and biological parameters such as pH, temperature, dissolved oxygen, total dissolved solids, electrical conductivity, turbidity, colour and total suspended solids, total hardness, total alkalinity, chloride, fluoride, nitrates-N, nitrites-N, ammonium-N, sulphates, total phosphate, sodium, calcium, magnesium and some heavy metals were analyzed. Total iron, lead, chromium, copper, zinc, manganese and cadmium were analyzed by atomic absorption spectrometry. Two of the basic biological parameters for drinking water such as faecal coliforms and salmonella were analyzed by incubation followed by counting colony forming units (CFUs). Statistical presentations of data including cluster analysis, dendrograms and principal component analysis were used with the assistance of PAST software. Temperature, pH, TDS dissolved oxygen, cations, anions (chemical parameters) and salmonella, faecal coliforms were the major contributing parameters to gravity flow water’s quality variations during both seasons. Values of pH ranged between 3.78 and 4.84 from March to August in all study sites and they were consistently below the WHO permissible pH range of 6.5 - 8.5. Total suspended solids ranged between 0.66 and 2.17 mg·L-1 and were above the recommended WHO limit of zero value in all study sites. Salmonella and faecal coliforms colonies were present in scaring numbers in the wet season. In March, salmonella counts at Kacuro (14 CFU) and Kanjobe (128 CFU) while faecal coliforms counts at Kacuro (515 CFU) and Kanjobe (228 CFU). The findings of this study call for special attention when using gravity flow water.展开更多
地铁站点辐射范围内的兴趣点(point of interest,POI)蕴含着丰富多样的时空特征。在相应时段内,POI会吸引大量交互客流。为精确捕捉POI对地铁客流的影响机理,提出一种多维兴趣点驱动的地铁客流多通道集成预测方法。首先,综合考虑地铁站...地铁站点辐射范围内的兴趣点(point of interest,POI)蕴含着丰富多样的时空特征。在相应时段内,POI会吸引大量交互客流。为精确捕捉POI对地铁客流的影响机理,提出一种多维兴趣点驱动的地铁客流多通道集成预测方法。首先,综合考虑地铁站点属性对客流的吸引作用、各类POI在不同时段内对客流吸引力的动态变化和各地铁站辐射范围内的POI种类数量和距离,分别构建站点客流吸引力公式、POI时间变化权重模型和POI空间流动交互矩阵。然后,提出一种多通道注意力集成的时空神经网络(multi channel attention spatio-temporal neural network,MCASTNN)客流预测模型,采用三分支结构,应用多种注意力机制挖掘多维POI与地铁客流间的深层关联性,通过多通道注意力集成机制进行特征融合,可有效提取地铁客流复杂的站点属性、时间和空间特征。最后,在杭州地铁AFC刷卡数据集上进行验证。结果表明:相较经典机器学习模型和深度学习模型,MCASTNN在居住主导型站点、工作主导型站点和混合商用型站点等多场景和不同时间步长下均具有更高预测精度,相较于Transformer在单步预测任务中均方根误差和平均绝对误差分别平均下降3.09和3.11。对POI特征和MCASTNN进行消融实验,验证了建模方法和各分支特征提取的有效性。该方法可为有关部门优化配置轨道站点资源、合理制定列车开行方案等提供参考。展开更多
基金Under the auspices of the National Natural Science Foundation of China! 49571027
文摘Through practical sampling survey for the overseas travelers in the 12 tourist hotspot cities of China, the analytical results of database of the spatial changes for overseas travelers have been established with the help of the software Visual FoxPro. The New concepts such as transferring state, which can be used to study the spatial flow intensity of travelers. is first put forward By analyzing the statistical results, the spatial flow intensity of 12 tourist hotspot cities in China for overseas travelers has been probed At last, a practical research of spatial flow intensity for overseas tourists is carried out in Beijing──the of tourist hotspots of China
基金The National Natural Science Foundation of China(41971272)。
文摘Research on spatial flow as it relates to the relationship between the supply and demand of ecosystem services supports a significant connection between the supply of ecosystem services and human well-being.Understanding the entire process of the production and flow,as well as the use of ecosystem services,accurately assessing the balance of supply and demand of ecosystem services,and establishing a two-way feedback relationship between supply and demand are vital for the scientific management of the ecosystem and ensuring the sustainable development of regional resources.Based on a large number of relevant publications,this paper comprehensively summarizes the concepts and assessment methods of ecosystem service supply and demand from the perspective of ecosystem service supply and demand,and discusses the impacts of land use and climate change on the temporal and spatial changes of ecosystem services under the background of global change.Then,an analysis of the research progress in the ecosystem services spatial flow indicated that there are still deficiencies in the quantification of cultural services,the dynamics of ecosystem service flow and the driving mechanism of ecosystem services.We also propose that clarifying the driving mechanism and transfer process of ecosystem services,and realizing the mutual conversion between different spatial-temporal scales of ecosystem services,is an important approach for improving the application of ecosystem services research in practice in the future.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 50478012 and 50436040).
文摘This paper puts forward a novel concept, the spatial flow influence factor (SFIF), which provides a new insight into the airflow structure. This concept is very helpful in the control of indoor air pollutants since: (1) for a given indoor airflow; given sources of volatile organic compounds (VOCs), the optimal arrangement of the VOC sources can easily be obtained; (2) for given positions of VOC sources; occupied regions (or target regions), the optimal indoor airflow pattern or organization can be determined; (3) the SFIF for an indoor space can also be regarded as the indoor air safety index of that space. To illustrate this concept, we present several examples of applying a SFIF to indoor air VOC control.
基金National Natural Science Foundation of China, No.40771019 Innovation Foundation of Shaanxi Normal University
文摘Although water has the central function of the bloodstream in the biosphere especially in arid or semi-arid regions such as Yah＇an region in northwestern China, yet the very limited attention is paid to the role of the water-related processes in ecosystem. In this research, based on continuous nearly 50-year data including runoff volume, sediment discharge as well as sediment accretion from hydrographic stations, and 10-year information of water quality from pollution monitoring stations, the method for measuring in-stream flow requirement has been put forward supported by experiential models and GIS spatial analysis. Additionally, the changes of in-stream flow requirement for environment and economic development have been addressed from spatial-temporal dimensions. The results show that： （1） According to the central streams in Yan＇an region, mean annual in-stream flow requirement reaches 1.0619 billion m^3, and the surface water for economic exploitation is 0.2445 billion m3 （2） Mean annual in-stream flow requirement for sediment transfers in flood period occupies over 80% of the integrated volume in a year. （3） From the 1950s to 1970s, in-stream flow requirement for sediment transfers is comparatively higher, while from the 1980s to 1990s, this requirement presents a decreasing tendency.
基金Foundation item: the National Natural Science Foundation of China for Outstanding Young Sci-entists (19925210)
文摘Different from previous temporal evolution assumption, the spatially growing mode was employed to analyze the linear stability for the channel flow of fiber suspensions. The stability equation applicable to fiber suspensions was established and solutions for a wide range of Reynolds number and angular frequency were given numerically . The results show that, the flow instability is governed by a parameter H which represents a ratio between the axial stretching resistance of fiber and the inertial force of the fluid. An increase of H leads to a raise of the critical Reynolds number, a decrease of corresponding wave number, a slowdown of the decreasing of phase velocity , a growth of the spatial attenuation rate and a diminishment of the peak value of disturbance velocity. Although the unstable region is reduced on the whole, long wave disturbances are susceptible to fibers.
基金supported by the National Natural Science Foundation of China(Grants No.41471025 and 40971021)the Natural Science Foundation of Shandong Province(Grant No.ZR2014DM004)
文摘In this study, we investigated the origin of the overland flow roughness problem and divided the current overland flow roughness research into three types, as follows: the first type of research takes into account the effects of roughness on the volume and velocity of surface runoff, flood peaks, and the scouring capability of flows, but has not addressed the spatial variability of roughness in detail; the second type of research considers that surface roughness varies spatially with different land usage types, land-cover conditions, and different tillage forms, but lacks a quantitative study of the spatial variability; and the third type of research simply deals with the spatial variability of roughness in each grid cell or land type. We present three shortcomings of the current overland flow roughness research, including(1) the neglect of roughness in distributed hydrological models when simulating the overland flow direction and distribution,(2) the lack of consideration of spatial variability of roughness in hydrological models, and(3) the failure to distinguish the roughness formulas in different overland flow regimes. To solve these problems,distributed hydrological model research should focus on four aspects in regard to overland flow: velocity field observations, flow regime mechanisms, a basic roughness theory, and scale problems.
文摘The study was designed to investigate temporal and spatial seasonal variations in quality properties of gravity flow water samples collected from Kigata, Kacuro, Kihanga, Kitibya and Kanjobe located in Kyanamira Sub-County, Kabale District, Uganda. Physical, chemical and biological parameters such as pH, temperature, dissolved oxygen, total dissolved solids, electrical conductivity, turbidity, colour and total suspended solids, total hardness, total alkalinity, chloride, fluoride, nitrates-N, nitrites-N, ammonium-N, sulphates, total phosphate, sodium, calcium, magnesium and some heavy metals were analyzed. Total iron, lead, chromium, copper, zinc, manganese and cadmium were analyzed by atomic absorption spectrometry. Two of the basic biological parameters for drinking water such as faecal coliforms and salmonella were analyzed by incubation followed by counting colony forming units (CFUs). Statistical presentations of data including cluster analysis, dendrograms and principal component analysis were used with the assistance of PAST software. Temperature, pH, TDS dissolved oxygen, cations, anions (chemical parameters) and salmonella, faecal coliforms were the major contributing parameters to gravity flow water’s quality variations during both seasons. Values of pH ranged between 3.78 and 4.84 from March to August in all study sites and they were consistently below the WHO permissible pH range of 6.5 - 8.5. Total suspended solids ranged between 0.66 and 2.17 mg·L-1 and were above the recommended WHO limit of zero value in all study sites. Salmonella and faecal coliforms colonies were present in scaring numbers in the wet season. In March, salmonella counts at Kacuro (14 CFU) and Kanjobe (128 CFU) while faecal coliforms counts at Kacuro (515 CFU) and Kanjobe (228 CFU). The findings of this study call for special attention when using gravity flow water.
