Dijkstra algorithm is a basic algorithm to analyze the vehicle routing problem (VRP) in the terminal distribution of logistics center. According to the actual client demands of service speed and quality, the conceptio...Dijkstra algorithm is a basic algorithm to analyze the vehicle routing problem (VRP) in the terminal distribution of logistics center. According to the actual client demands of service speed and quality, the conceptions of economical distance of delivery and the best routing algorithm were given on the base of the Dijkstra algorithm with consideration of a coefficient of the road hustle degree. Economical distance of delivery is the shortest physical distance between two customers. It is the value of goods delivery in shortest distance when concerning factors such as the road length, the hustle degree, the driveway quantity, and the type of the road. The improved algorithm is being used in the development and application of a distribution path information system in the terminal distribution of logistics center. The simulation and practical case prove that the algorithm is effective and reasonable.展开更多
The present study aims to propose the method for the quantitative evaluation of safety concerning evacuation routes in case of earthquake disasters in urban areas using ACO （Ant Colony Optimization） algorithm and G...The present study aims to propose the method for the quantitative evaluation of safety concerning evacuation routes in case of earthquake disasters in urban areas using ACO （Ant Colony Optimization） algorithm and GIS （Geographic Information Systems）. Regarding the safety evaluation method, firstly, the similarity in safety was focused on while taking into consideration road blockage probability, and after classifying roads by means of the hierarchical cluster analysis, the congestion rates of evacuation routes using ACO simulations were estimated. Based on these results, the multiple evacuation routes extracted were visualized on digital maps by means of GIS, and its safety was evaluated. Furthermore, the selection of safe evacuation routes between evacuation sites, for cases when the possibility of large-scale evacuation after an earthquake disaster is high, is made possible. As the safety evaluation method is based on public information, by obtaining the same geographic information as the present study, it is effective in other areas regardless of whether the information is of the past and future. Therefore, in addition to spatial reproducibility, the safety evaluation method also has high temporal reproducibility. Because safety evaluations are conducted on evacuation routes based on quantified data, highly safe evacuation routes that are selected have been quantitatively evaluated, and thus serve as an effective indicator when selecting evacuation routes.展开更多
Recently, smart grid solutions have started to extend the visibility of the electrical grid to the entire network; including high voltage transmission lines, medium voltage distribution networks, and the low voltage n...Recently, smart grid solutions have started to extend the visibility of the electrical grid to the entire network; including high voltage transmission lines, medium voltage distribution networks, and the low voltage networks to households. The typical data monitored includes： voltage, current, phase, and power measurements, together with network events and alarms. This paper analyses the key challenges facing smart grid solutions in providing effective access to large volumes of sensory data that is distributed over a large geographic area. A case study is described that outlines how the use of geospatial technology together with Web 2.0 technologies may be applied to improve user access and control to this data. The results show that a geospatial solution provides an effective mechanism for visualizing telemetry data monitored within the smart grid.展开更多
Electric power systems usually cover large geographical areas and transmission facilities are continuously increasing. These power systems are exposed to different environmental conditions which may cause faults to oc...Electric power systems usually cover large geographical areas and transmission facilities are continuously increasing. These power systems are exposed to different environmental conditions which may cause faults to occur on the system. Different types of studies are usually done on electric power systems to determine how the system behaves before, during and after a fault condition. The behaviour of variables of interest such as currents, voltage, rotor angle and active and reactive power under fault conditions are studied and observed to help determine possible causes of faults in a power system. The objective of this paper is to investigate a fault that occurred on the 330 kV transmission line between Ruacana power station and Omburu sub-station, the fault caused all the generators at Ruacana power station to trip and consequently caused a blackout at the power station that lasted for 6 h. Preliminary findings showed that the observed fault was an earth fault but the exact type of earth fault was however not known at the time. This research investigation sets out to determine the exact fault that occurred; the most probable cause of the fault, and propose possible solutions to prevent reoccurrence of such a fault. The section of the power network in which the fault occurred was modelled using DigSilent Power Factory software tool, and transient fault analysis was carried out on the model for different fault conditions. Results obtained were then compared with data obtained from NamPower records to ascertain the type of fault.展开更多
Wuliangsuhai wetland is one of the representative wetlands in arid-semiarid region. It is also a key breeding site as well as a stepping site for both East Asia-Australasia Flyway and Central Asia Flyway. From 2009 to...Wuliangsuhai wetland is one of the representative wetlands in arid-semiarid region. It is also a key breeding site as well as a stepping site for both East Asia-Australasia Flyway and Central Asia Flyway. From 2009 to 2012, surveys on migratory water birds and their habitat were carried out by using transects census and spot count methods. The surveys recorded more than 100 000 water birds, and 98 species were identified, which belong to 6 orders and 14 families. Among the 98 species, 55 are summer residents （breeding here） and 39 are travelers （only stay here shortly）, which account for 56.12% and 39.80% of the total recorded bird species respectively. Further analysis on their migration pattern shows that spring migration is mainly from early March to mid May, which is shorter than autumn migration season （from early August to mid November）. Most of the summer residents breed from early April to late May. High concentration of key protected species were observed from early April to early May and from early September to early November. The bird community structure is relatively stable in summer, but much more dynamic during the migration seasons （spring and autumn）. Based on the study, recommendation to nominate Wuliangsuhai wetlands as Ramsar site, and flyway network site were put forward. Habitat management that address to the environmental determinants on bird distribution was also discussed.展开更多
基金Social Science Fund of Zhejiang Province(No 06CGGL22YBG)
文摘Dijkstra algorithm is a basic algorithm to analyze the vehicle routing problem (VRP) in the terminal distribution of logistics center. According to the actual client demands of service speed and quality, the conceptions of economical distance of delivery and the best routing algorithm were given on the base of the Dijkstra algorithm with consideration of a coefficient of the road hustle degree. Economical distance of delivery is the shortest physical distance between two customers. It is the value of goods delivery in shortest distance when concerning factors such as the road length, the hustle degree, the driveway quantity, and the type of the road. The improved algorithm is being used in the development and application of a distribution path information system in the terminal distribution of logistics center. The simulation and practical case prove that the algorithm is effective and reasonable.
文摘The present study aims to propose the method for the quantitative evaluation of safety concerning evacuation routes in case of earthquake disasters in urban areas using ACO （Ant Colony Optimization） algorithm and GIS （Geographic Information Systems）. Regarding the safety evaluation method, firstly, the similarity in safety was focused on while taking into consideration road blockage probability, and after classifying roads by means of the hierarchical cluster analysis, the congestion rates of evacuation routes using ACO simulations were estimated. Based on these results, the multiple evacuation routes extracted were visualized on digital maps by means of GIS, and its safety was evaluated. Furthermore, the selection of safe evacuation routes between evacuation sites, for cases when the possibility of large-scale evacuation after an earthquake disaster is high, is made possible. As the safety evaluation method is based on public information, by obtaining the same geographic information as the present study, it is effective in other areas regardless of whether the information is of the past and future. Therefore, in addition to spatial reproducibility, the safety evaluation method also has high temporal reproducibility. Because safety evaluations are conducted on evacuation routes based on quantified data, highly safe evacuation routes that are selected have been quantitatively evaluated, and thus serve as an effective indicator when selecting evacuation routes.
文摘Recently, smart grid solutions have started to extend the visibility of the electrical grid to the entire network; including high voltage transmission lines, medium voltage distribution networks, and the low voltage networks to households. The typical data monitored includes： voltage, current, phase, and power measurements, together with network events and alarms. This paper analyses the key challenges facing smart grid solutions in providing effective access to large volumes of sensory data that is distributed over a large geographic area. A case study is described that outlines how the use of geospatial technology together with Web 2.0 technologies may be applied to improve user access and control to this data. The results show that a geospatial solution provides an effective mechanism for visualizing telemetry data monitored within the smart grid.
文摘Electric power systems usually cover large geographical areas and transmission facilities are continuously increasing. These power systems are exposed to different environmental conditions which may cause faults to occur on the system. Different types of studies are usually done on electric power systems to determine how the system behaves before, during and after a fault condition. The behaviour of variables of interest such as currents, voltage, rotor angle and active and reactive power under fault conditions are studied and observed to help determine possible causes of faults in a power system. The objective of this paper is to investigate a fault that occurred on the 330 kV transmission line between Ruacana power station and Omburu sub-station, the fault caused all the generators at Ruacana power station to trip and consequently caused a blackout at the power station that lasted for 6 h. Preliminary findings showed that the observed fault was an earth fault but the exact type of earth fault was however not known at the time. This research investigation sets out to determine the exact fault that occurred; the most probable cause of the fault, and propose possible solutions to prevent reoccurrence of such a fault. The section of the power network in which the fault occurred was modelled using DigSilent Power Factory software tool, and transient fault analysis was carried out on the model for different fault conditions. Results obtained were then compared with data obtained from NamPower records to ascertain the type of fault.
基金National Science and Technology Support Program (2008BADB0B02)
文摘Wuliangsuhai wetland is one of the representative wetlands in arid-semiarid region. It is also a key breeding site as well as a stepping site for both East Asia-Australasia Flyway and Central Asia Flyway. From 2009 to 2012, surveys on migratory water birds and their habitat were carried out by using transects census and spot count methods. The surveys recorded more than 100 000 water birds, and 98 species were identified, which belong to 6 orders and 14 families. Among the 98 species, 55 are summer residents （breeding here） and 39 are travelers （only stay here shortly）, which account for 56.12% and 39.80% of the total recorded bird species respectively. Further analysis on their migration pattern shows that spring migration is mainly from early March to mid May, which is shorter than autumn migration season （from early August to mid November）. Most of the summer residents breed from early April to late May. High concentration of key protected species were observed from early April to early May and from early September to early November. The bird community structure is relatively stable in summer, but much more dynamic during the migration seasons （spring and autumn）. Based on the study, recommendation to nominate Wuliangsuhai wetlands as Ramsar site, and flyway network site were put forward. Habitat management that address to the environmental determinants on bird distribution was also discussed.
