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Objectives: The study of medical facilities accessibility is a critical method to analyze the convenience of accessing medical services in a region. Existing research mainly focuses on potential accessibility (PA) research, and few studies have analyzed the revealed accessibility (RA) based on the actual use of medical facilities. Methods: The main urban area of Chengdu City, Sichuan Province, China, is taken as the study area, and the actual travel distance decay function is fitted by introducing the user̓s actual choice weight and the comprehensive service capacity of healthcare facilities using droplet travel data to improve the three-step search method model for calculating RA. Then, we compare it with the PA calculated based on the service capacity of medical facilities and potential medical needs to analyze the degree of mismatch between them, identify the types of community access to medical facilities, and analyze their spatial distribution characteristics. Results: The PA is mainly affected by the travel time, and the difference between the central area and the peripheral area is large, but the difference between different districts is not obvious. The RA is mainly affected by the number of medical trips, and the difference between each district is obvious. 182 communities with “RA>PA” are mainly distributed in Chenghua District and Jinniu District, and 243 communities with “RA

Objectives: Buffer analysis is a common tool of spatial analysis, which deals with the problem of proximity. Due to numerous and complex operations in the algorithm, the computational efficiency needs to be optimized. Methods: To process large scale point features, a graph-based representation model is pro⁃ posed, which establishes the spatial computational domain for data and analysis, and develops a well-balanced task-partitioning method by partitioning the graph. First, the proposed model defines processing functions of point features and their spatial relationships from the perspectives of graph nodes and graph edges, and provides a logic description for buffer zone generation around point features. Second, the computational weights of graph nodes and graph edges are obtained by fitting the time complexity of the above processing functions. Finally, graph partitioning is adopted to divide the buffer task, which contributes to multiple parallel tasks matching with the computational resources. Results: The experimental results show that graphbased buffer analysis can achieve better load balance and overall efficiency, which is superior to the main⁃ stream partitioning methods, regular-grid and quadtree. Conclusions: The proposed method can provide a reference for optimization of spatial analysis methods when processing large scale vector data. [ABSTRACT FROM AUTHOR]

Objectives: At present, China has invested a large amount of resources in improving primary medical and health services. Aiming at 15 min medical circle, a variety of primary medical security facilities such as clinics and medical insurance stations have been built. Evaluation of their accessibility is of great sig‐ nificance for rational planning and optimization of facilities. Methods: We made full use of pan-map resources such as online map, population thermal map, path planning service and isochronous circle range service, and improved the Huff-based two-step floating catchment area method (Huff 2SFCA) from the perspective of travel capacity difference and day and night population distribution difference,and formed a 15 min nucleic acid sampling circle evaluation framework. Results: Taking Shanghai as an example to analyze the accessi‐ bility of medical facilities in 15 min living circle, the results show that: (1) In all administrative districts ex‐ cept Baoshan and Pudong in the study area, the area coverage and population coverage of the 15 min sam‐ pling circle are above 90%, among which Hongkou and Jingan have the highest accessibility. (2) Affected by the separation between work and housing of commuters, the areas with large permanent residents tend to have high accessibility during the day, and the accessibility decreases at night. On the contrary, the areas with industrial clusters have significantly higher accessibility at night. (3) The surrounding development zones such as Pudong and Baoshan show the characteristics of polarization of accessibility. The accessibility of well-developed residential areas is high, while the accessibility of developing new industrial parks is low. The accessibility distribution of the old city is relatively more balanced, and can better meet the needs of the elderly and the working population.Conclusions:The results show that the current spatial layout of sam‐ pling stations considers the travel behavior of residents, and can meet the needs of most residents for test‐ ing near their residence and work place. For areas with high or low accessibility, the resource allocation of sampling points can be optimized according to the diurnal variation of population distribution. [ABSTRACT FROM AUTHOR]

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Objective: The landslide susceptibility assessment can provide important scientific basis for landslide hazard risk management, land space planning and landslide monitoring. Shaanxi Province, located in northwestern China, is a key area for the prevention and control of landslides in the country. Shaanxi Province has active geological tectonic movements,complex geological conditions,and is affected by various factors such as engineering construction, land resource utilization, mineral resource development, and heavy rainfall. The effects of landslide hazards have increased significantly. Therefore, it is of great practical significance to monitor and predict landslide disasters in Shaanxi Province. Methods: Considering that the existing landslide hazard susceptibility evaluation models cannot eliminate the differences in dimensionality and properties of susceptibility evaluation index factors, we take into account the correlation between susceptibility evaluation index factors and landslide hazard, especially the Methods: based on classic machine learning with high accuracy still exist some problems such as low training efficiency and difficult parameter selection, landslide susceptibility assessment method incorporating index of entropy based on support vector machine (SVM) is presented using index of entropy (IOE) and particle swarm optimization algorithm(PSO).First,based on the landslide susceptibility evaluation index factors，8 evaluation factors are selected, such as elevation, slope, aspect, distance from residential area, distance from road, distance from river, lithology and cumulative rainfall. In order to ensure the balance of sample units and the uniform distribution and reduction of non‑landslide hazard unit error,non‑hazard units with the same number of hazard units are selected randomly in the area 1 km away from the existing hazard point. All the non‑hazard units and hazard units are taken as the training data set and verification data set. Then the IOE model is used to calculate the adjustment factor supporting SVM, the PSO algorithm applied to iteratively solve the optimal penalty factor and radial basis kernel function of SVM, and the susceptibility of landslide hazards is obtained according to the membership of the SVM binary classification. At last, the susceptibility partition is divided by the natural breakpoint method. Results Selecting Shaanxi Province as the experimental area, the proposed method is compared with the SVM method from the three aspects of landslide hazard susceptibility partition map, partition statistics and evaluation model accuracy. Compared with the SVM model, the hazard susceptibility is improved one level is more reasonable for hazard susceptibility zoning in some areas with hazard point distribution. With the increase of hazard susceptibility, the percent of landslide hazard points in each subregion of the two models also gradually increased, reaching the highest in extremely high incidence areas, especially in extremely high incidence areas. The percent of landslide hazard points in the proposed method reached 58.64%, higher than the SVM method. Conclusions: In the landslide hazard‑prone area divided by the proposed method, the point density of hazard points is higher, which is more in line with the actual hazard distribution.The receiver operating characteristic(ROC) curve shows that the area under curve(AUC) value of the proposed method is 0.89, and the SVM method is 0.82, which is higher than SVM. Based on the experimental Results:,it is shown that the accuracy and reliability of the proposed method is superior to the SVM method. [ABSTRACT FROM AUTHOR]

Objective: Emergency location is one of the key technologies for emergency rescue of major emergencies such as earthquake, fire, mine accident and so on. However, at the present stage, the research on the theory and technology of emergency location is still not systematized, the rapid construction method of seamless benchmark and collaborative location model for emergency location are not robust enough, and the lack of positioning terminals has become an urgent problem to be solved. Methods: Firstly, we expound the research status at home and abroad according to the three commonly used emergency positioning modes of GNSS(global navigation satellite system), autonomous positioning and local area network electromagnetic wave positioning.Secondly, based on the technologies of emergency CORS(continuously operating reference stations) and UWB(ultra wide band) networking, a general emergency seamless positioning solution for many kinds of disasters is constructed. Then, the key technologies such as low power consumption of emergency positioning terminal manufacturing, synchronous information acquisition and efficient calculation of embedded firmware are overcome, and hardware equipment such as GNSS/UWB base station is developed. And, the emergency location service system is designed and developed, which solves the problems of emergency position networking, personnel location and on-site scheduling. Finally, the message transmission protocol of emergency navigation and location service system is proposed, which promotes the development of emergency rescue equipment standardization. Results: Through the research on the key technologies such as the manufacture of emergency location terminals such as GNSS/UWB base station, the development of emergency location and location service system based on cloud platform, and the formulation of message transmission protocol of emergency navigation and location service system, we put forward a seamless positioning solution for indoor and outdoor under emergency conditions, which solves the problems of rapid construction of indoor and outdoor seamless positioning datum, personnel positioning and command scheduling in emergency. Conclusions: The purpose is to create an emergency-oriented indoor seamless positioning technology system and innovate the existing emergency positioning technology Methods. [ABSTRACT FROM AUTHOR]

Objective: China is one of the countries with the most severe natural disasters in the world. There are many types of natural disasters and high frequency of disasters. It often causes huge economic losses and casualties in the disaster area. Combining the key technologies of the internet of things(IOT), the Internet, and geographic information for surveying and mapping, so it is possible to grasp the disaster situation in a timely and efficient manner. Thereby we could scientifically and effectively formulate disaster prevention and mitigation strategies, and implement emergency rescue measures, which are of great significance to the safety of people’s lives and property. Methods: The development of big data and disaster reduction technologies has brought new possibilities for disaster management and emergency response. Geographic information big data provides basic support for emergency rapid response, location and navigation big data provides location information of personnel and materials for emergency rescue. Two- and three-dimensional visualization technology more realistically restores the disaster environment, and disaster models scientifically simulate the process of disaster occurrence, internet public opinion big data in disaster assessment also plays an important role. Big data is profoundly changing emergency rescue and disaster management with its ability to visualize, analyze and predict disasters. The combination of disaster big data and surveying and mapping geographic information technology has become an important means to improve disaster prevention and mitigation capabilities. Results: We analyze and summary the integrated and comprehensive disaster reduction technology in the context of big data. The characteristics of integrated and comprehensive disaster reduction technology are elaborated, including comprehensive and thorough perception, broadband ubiquitous interconnection, precise and fast integration, ubiquitous positioning, efficient and intelligent processing, and intelligent collaborative services. The progress of integrated comprehensive disaster reduction technology is reviewed, which includes indoor and outdoor high-precision integrated positioning, rapid integration of multi-source data, scene fusion and enhanced visualization, typical disaster model construction and management, integrated disaster reduction comprehensive services, and China’s disaster reduction service system platform. In addition, we introduced the integrated comprehensive disaster reduction intelligent service system platform, APP and its application services, and summarized and prospected the integrated comprehensive disaster reduction technology and services. Conclusions: The continuous development of big data technology provides new ideas and Methods: for people to analyze and solve emergency response problems, and provides a very convenient way for the sharing, integration, analysis, mining, and decision-making of comprehensive disaster reduction services. However, with the in-depth application of new concepts, new technologies, and new Methods: such as "Internet +", IoT, cloud computing, artificial intelligence, and mobile communications in the field of comprehensive disaster reduction, the means of acquisition, transmission efficiency, application deployment Methods:, and services of comprehensive disaster reduction data Modes, data production and processing Methods:, target users, etc. have undergone profound changes. This leads to the characteristics of crowd sourced disaster data acquisition, diversified data storage models, and comprehensive analysis services, which brings new opportunities and challenges to the development of integrated disaster reduction services. [ABSTRACT FROM AUTHOR]

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Statistical analysis is an important way of extracting information from the national geographical conditions data. It can reflect the internal spatial characteristics of resources? environment, ecology and economy, and their interactions from different dimensions. In view of the high-efficiency management, high intensity computation and deep-level service for statistical analysis based on the big data, this paper puts forward a technical framework of national geographical conditions statistical a-nalysis. and discusses the core process of statistical analysis from three dimensions; big data storage and integration, key technologies for statistical computation, service modeling and application. This paper will help to improve the application level of national geographical conditions monitoring and statistical analysis service in natural resources supervision, ecological protection and restoration, etc. . and can promote the transformation and upgrading of geographical information industry in China. [ABSTRACT FROM AUTHOR]

Geo-spatial information technology can provide data resources, positioning benchmarks, basic framework and key technologies for disaster prevention and reduction. At present, there are some problems in Chinese disaster reduction services. Too much emphasis is placed on decision-ma-king and not on early warning. In addition, the technology, system and application integration of di-saster reduction services is not enough. There is still a lack of a unified understanding and a holistic top-level design guidance framework of disaster reduction services. In order to solve these technical problems of integrated perception, location, integration and comprehensive scene simulation of emergency information such as disaster events, various disaster-bearing bodies, the disaster-pregnant environment, and knowledgeable disaster reduction services, this paper returns to the nature of disaster reduction services, puts forward and explains the concept, connotation and characteristics of the integrated disaster reduction intelligent services from the perspective of surveying, mapping and geoinformation. Besides, an integrated disaster mitigation intelligence services architecture is designed with the consideration of the demand for disaster prevention and reduction services. This enterprise architecture is composed of the perception layer, the technology layer, the system layer and the application layer. Then, this paper forms the intelligence, totalization, integration, accurate, rapid and novelty thinking of disaster reduction services. Finally, the supporting technologies of disaster reduction ser-vices are presented and the comprehensive disaster reduction system is introduced. The proposed top-level design for the integrated disaster reduction intelligent services can solve the integrated perception, positioning, integration and simulation of the scene, and intellectualized disaster reduction ser-vices and other technical problems. [ABSTRACT FROM AUTHOR]

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)