This paper investigates a unmanned aerial vehicle(UAV)deployment problem in a non-orthogonal multiple access(NOMA)system,where the UAV is deployed as an aerial mobile base station to transmit data to two ground users....This paper investigates a unmanned aerial vehicle(UAV)deployment problem in a non-orthogonal multiple access(NOMA)system,where the UAV is deployed as an aerial mobile base station to transmit data to two ground users.An optimization problem is formulated by deploying the UAV for maximizing the sum rate of the two users.In order to solve the optimization problem,the feasible solution region is first reduced to a line segment between two users.Then,the optimization problem is simplified to a univariate problem,which can be solved by derivation under a certain situation,and the corresponding analytical solution is also provided.Moreover,a generalized algorithm,which considers 2 situations,is proposed to further determine the optimal UAV’s location.Specifically,four cases are discussed in the first situation.Extensive simulations are depicted to demonstrate effectiveness of the proposed algorithm and its superiority over the benchmarks in maximizing the two users’sum rate.展开更多
The problem of accessibility of health institution, with respect to the available facility to serve the entire population leaving in an area, can be solved using GIS. This paper presents an analysis on accessibility o...The problem of accessibility of health institution, with respect to the available facility to serve the entire population leaving in an area, can be solved using GIS. This paper presents an analysis on accessibility of healthcare facilities in Enugu urban area in a GIS environment. This was achieved through acquisition of a base map of Enugu State showing geographic extent of Enugu Urban, determining the geometric positions of health institutions in Enugu urban using handheld GPS, Creation of a spatial database of existing healthcare facilities and demonstrating through various analyses the potentials of GIS in measurement of accessibility to healthcare facilities in Enugu urban Area. The analysis includes network analysis, used to determine the closeness of a facility and shortest route to these healthcare facilities. ARCGIS 9.3 was the main software used. This was supported by Geocal for coordinate conversion and Microsoft office packages. The result of the study showed the spatial distribution of health institutions, closest facilities in case of emergency and route to those health institutions within Enugu urban Area. It was noticed that most of the healthcare facilities were located within Enugu North local government area (LGA). Other settlements and LGAs had fewer healthcare facilities. Areas deprived of healthcare facility were also identified. Routes and closest facilities to those deprived areas were identified in the settlements/area. The analysis showed the efficacy of GIS in determining accessibility of healthcare institutions in Enugu urban area. The study is thus, recommended as a spatial decision support system for decisions regarding spatial accessibility of healthcare facilities in an urban area.展开更多
Data organization requires high efficiency for large amount of data applied in the digital mine system. A new method of storing massive data of block model is proposed to meet the characteristics of the database, incl...Data organization requires high efficiency for large amount of data applied in the digital mine system. A new method of storing massive data of block model is proposed to meet the characteristics of the database, including ACID-compliant, concurrency support, data sharing, and efficient access. Each block model is organized by linear octree, stored in LMDB（lightning memory-mapped database）. Geological attribute can be queried at any point of 3D space by comparison algorithm of location code and conversion algorithm from address code of geometry space to location code of storage. The performance and robustness of querying geological attribute at 3D spatial region are enhanced greatly by the transformation from 3D to 2D and the method of 2D grid scanning to screen the inner and outer points. Experimental results showed that this method can access the massive data of block model, meeting the database characteristics. The method with LMDB is at least 3 times faster than that with etree, especially when it is used to read. In addition, the larger the amount of data is processed, the more efficient the method would be.展开更多
基金the National Natural Science Foundation of China(No.61702258,61901211)the Natural Science Foundation of Jiangsu Province(No.BK20170766).
文摘This paper investigates a unmanned aerial vehicle(UAV)deployment problem in a non-orthogonal multiple access(NOMA)system,where the UAV is deployed as an aerial mobile base station to transmit data to two ground users.An optimization problem is formulated by deploying the UAV for maximizing the sum rate of the two users.In order to solve the optimization problem,the feasible solution region is first reduced to a line segment between two users.Then,the optimization problem is simplified to a univariate problem,which can be solved by derivation under a certain situation,and the corresponding analytical solution is also provided.Moreover,a generalized algorithm,which considers 2 situations,is proposed to further determine the optimal UAV’s location.Specifically,four cases are discussed in the first situation.Extensive simulations are depicted to demonstrate effectiveness of the proposed algorithm and its superiority over the benchmarks in maximizing the two users’sum rate.
基金Funded by the National Natural Science Foundation of China(Grant No.50375071) ,the National Natural Science Foundation of Jiangsu Province Education Department ( Grant No. 2004JD028J) and the Science Foundation of Zhenjiang City( Grant No.2004JD020J)
文摘The problem of accessibility of health institution, with respect to the available facility to serve the entire population leaving in an area, can be solved using GIS. This paper presents an analysis on accessibility of healthcare facilities in Enugu urban area in a GIS environment. This was achieved through acquisition of a base map of Enugu State showing geographic extent of Enugu Urban, determining the geometric positions of health institutions in Enugu urban using handheld GPS, Creation of a spatial database of existing healthcare facilities and demonstrating through various analyses the potentials of GIS in measurement of accessibility to healthcare facilities in Enugu urban Area. The analysis includes network analysis, used to determine the closeness of a facility and shortest route to these healthcare facilities. ARCGIS 9.3 was the main software used. This was supported by Geocal for coordinate conversion and Microsoft office packages. The result of the study showed the spatial distribution of health institutions, closest facilities in case of emergency and route to those health institutions within Enugu urban Area. It was noticed that most of the healthcare facilities were located within Enugu North local government area (LGA). Other settlements and LGAs had fewer healthcare facilities. Areas deprived of healthcare facility were also identified. Routes and closest facilities to those deprived areas were identified in the settlements/area. The analysis showed the efficacy of GIS in determining accessibility of healthcare institutions in Enugu urban area. The study is thus, recommended as a spatial decision support system for decisions regarding spatial accessibility of healthcare facilities in an urban area.
基金Projects(41572317,51374242)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by the Innovation Driven Plan of Central South University,China
文摘Data organization requires high efficiency for large amount of data applied in the digital mine system. A new method of storing massive data of block model is proposed to meet the characteristics of the database, including ACID-compliant, concurrency support, data sharing, and efficient access. Each block model is organized by linear octree, stored in LMDB（lightning memory-mapped database）. Geological attribute can be queried at any point of 3D space by comparison algorithm of location code and conversion algorithm from address code of geometry space to location code of storage. The performance and robustness of querying geological attribute at 3D spatial region are enhanced greatly by the transformation from 3D to 2D and the method of 2D grid scanning to screen the inner and outer points. Experimental results showed that this method can access the massive data of block model, meeting the database characteristics. The method with LMDB is at least 3 times faster than that with etree, especially when it is used to read. In addition, the larger the amount of data is processed, the more efficient the method would be.
