A NOVEL APPROACH OF INDEXING AND RETRIEVING SPATIAL POLYGONS FOR EFFICIENT SPATIAL REGION QUERIES

Spatial region queries are more and more widely used in web-based applications. Mechanisms to provide efficient query processing over geospatial data are essential. However, due to the massive geospatial data volume, heavy geometric computation, and high access concurrency, it is difficult to get response in real time. Spatial indexes are usually used in this situation. In this paper, based on k-d tree, we introduce a distributed KD-Tree (DKD-Tree) suitbable for polygon data, and a two-step query algorithm. The spatial index construction is recursive and iterative, and the query is an in memory process. Both the index and query methods can be processed in parallel, and are implemented based on HDFS, Spark and Redis. Experiments on a large volume of Remote Sensing images metadata have been carried out, and the advantages of our method are investigated by comparing with spatial region queries executed on PostgreSQL and PostGIS. Results show that our approach not only greatly improves the efficiency of spatial region query, but also has good scalability, Moreover, the two-step spatial range query algorithm can also save cluster resources to support a large number of concurrent queries. Therefore, this method is very useful when building large geographic information systems.

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Web Based GIS Application using Open Source Software for Sharing Geospatial Data

International Journal of Advanced Remote Sensing and GIS ◽

10.23953/cloud.ijarsg.109 ◽

2015 ◽

Vol 4 (1) ◽

pp. 1224-1228 ◽

Cited By ~ 9

Author(s):

Debasish Chakraborty ◽

◽

Debanjan Sarkar ◽

Shubham Agarwal ◽

Dibyendu Dutta ◽

...

Keyword(s):

Open Source ◽

Open Source Software ◽

Geospatial Data ◽

Web Based ◽

Gis Application

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HiBuffer: Buffer Analysis of 10-Million-Scale Spatial Data in Real Time

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi7120467 ◽

2018 ◽

Vol 7 (12) ◽

pp. 467 ◽

Cited By ~ 3

Author(s):

Mengyu Ma ◽

Ye Wu ◽

Wenze Luo ◽

Luo Chen ◽

Jun Li ◽

...

Keyword(s):

Real Time ◽

Spatial Data ◽

High Performance ◽

Large Scale ◽

Computation Time ◽

Buffer Analysis ◽

Data Volume ◽

Time Buffer ◽

Real World Datasets ◽

Spatial Indexes

Buffer analysis, a fundamental function in a geographic information system (GIS), identifies areas by the surrounding geographic features within a given distance. Real-time buffer analysis for large-scale spatial data remains a challenging problem since the computational scales of conventional data-oriented methods expand rapidly with increasing data volume. In this paper, we introduce HiBuffer, a visualization-oriented model for real-time buffer analysis. An efficient buffer generation method is proposed which introduces spatial indexes and a corresponding query strategy. Buffer results are organized into a tile-pyramid structure to enable stepless zooming. Moreover, a fully optimized hybrid parallel processing architecture is proposed for the real-time buffer analysis of large-scale spatial data. Experiments using real-world datasets show that our approach can reduce computation time by up to several orders of magnitude while preserving superior visualization effects. Additional experiments were conducted to analyze the influence of spatial data density, buffer radius, and request rate on HiBuffer performance, and the results demonstrate the adaptability and stability of HiBuffer. The parallel scalability of HiBuffer was also tested, showing that HiBuffer achieves high performance of parallel acceleration. Experimental results verify that HiBuffer is capable of handling 10-million-scale data.

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Evaluating the Performance of Novel JWT Revocation Strategy

Acta Cybernetica ◽

10.14232/actacyb.289455 ◽

2021 ◽

Author(s):

László Viktor Jánoky ◽

Péter Ekler ◽

János Levendovszky

Keyword(s):

Access Control ◽

Real World ◽

Mathematical Framework ◽

Web Based ◽

Novel Approach ◽

User Access ◽

Digital Signing

JSON Web Tokens (JWT) provide a scalable, distributed way of user access control for modern web-based systems. The main advantage of the scheme is that the tokens are valid by themselves – through the use of digital signing – also imply its greatest weakness. Once issued, there is no trivial way to revoke a JWT token. In our work, we present a novel approach for this revocation problem, overcoming some of the problems of currently used solutions. To compare our solution to the established solutions, we also introduce the mathematical framework of comparison, which we ultimately test using real-world measurements.

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A novel approach for semi-supervised classification of remote sensing images using a clustering-based selection of training data according to their GMM responsibilities

2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) ◽

10.1109/igarss.2017.8128058 ◽

2017 ◽

Cited By ~ 2

Author(s):

Victor-Emil Neagoe ◽

Vlad Chirila-Berbentea

Keyword(s):

Remote Sensing ◽

Supervised Classification ◽

Training Data ◽

Remote Sensing Images ◽

Novel Approach ◽

Selection Of

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Development of a Web-Based System for Diagnosing Student Learning Problems on English Tenses

Web-Based Education ◽

10.4018/978-1-61520-963-7.ch121 ◽

2010 ◽

pp. 1825-1843

Author(s):

Gwo-Jen Hwang ◽

Hsiang Cheng ◽

Carol H.C. Chu ◽

Judy C.R. Tseng ◽

Gwo-Haur Hwang

Keyword(s):

Native English Speakers ◽

Learning Problems ◽

English Speakers ◽

English Learning ◽

The Novel ◽

Web Based ◽

Novel Approach ◽

The World ◽

Web Based System ◽

English Verb

In the past decades, English learning has received lots of attention all over the world, especially for those who are not native English speakers. Various English learning and testing systems have been developed on the Internet. Nevertheless, most existing English testing systems represent the learning status of a student by assigning that student with a score or grade. This approach makes the student aware of his/her learning status through the score or grade, but the student might be unable to improve his/her learning status without further guidance. In this paper, an intelligent English tense learning and diagnosticsystem is proposed, which is able to identify studentlearning problems on English verb tenses and to provide personalized learning suggestions in accordance with eachstudent’s learning portfolio. Experimental results on hundreds of college students have depicted the superiority of the novel approach.

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Evaluator: A Multilevel Decision Approach for Web-Based Landmark Evaluation

Security and Communication Networks ◽

10.1155/2020/8843188 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Meijuan Yin ◽

Wen Yang ◽

Xiaonan Liu ◽

Xiangyang Luo

Keyword(s):

Evaluation Methods ◽

Layer By Layer ◽

Domain Name ◽

Web Based ◽

Verification Algorithm ◽

Street Level ◽

Distributed Query ◽

Evaluation Approach ◽

Public Data ◽

Query Algorithm

Street-level landmarks are an important basis for street-level IP geolocation, and the web-based landmark is one of the main sources of street-level landmarks. Considering the existing street-level landmark evaluation methods having low accuracy and strict constraints, this paper analyses the causes and evaluation idea of invalid web-based candidate landmarks and proposes Evaluator, a web-based landmark evaluation approach. Evaluator adopts the idea of the decision tree to filter invalid landmarks layer by layer and comprehensively estimates the quantitative reliability of candidate landmarks with public data and services to obtain reliable landmarks. This paper proposes the domain name system (DNS) distributed query algorithm to effectively resolve all IP addresses of a domain name, which provides data support for Evaluator to filter candidate landmarks. Meanwhile, this paper also proposes a reverse verification algorithm to obtain all domain names of an IP address, which provides an important reference to calculate the reliability of a reliable landmark. In addition, gradient descent is used to assess the parameters of the reliability estimating model, which effectively improves the robustness of Evaluator. Experiments show that reliable landmarks from Evaluator reduce the geolocation error of 100 targets in Hong Kong from 7.30 km to 3.91 km, compared with the landmark verifying method (LVM), one of the latest web-based landmark evaluation methods. Moreover, Evaluator significantly improves the evaluation coverage based on the same geolocation accuracy with street-level landmark evaluation (SLE), one of the latest landmark evaluation methods.

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A Novel Approach to Practice-Based Learning and Improvement Using a Web-Based Audit and Feedback Module

Journal of Graduate Medical Education ◽

10.4300/jgme-d-14-00016.1 ◽

2014 ◽

Vol 6 (3) ◽

pp. 541-546 ◽

Cited By ~ 4

Author(s):

Joel C. Boggan ◽

George Cheely ◽

Bimal R. Shah ◽

Randy Heffelfinger ◽

Deanna Springall ◽

...

Keyword(s):

Phase 1 ◽

Data Entry ◽

Audit And Feedback ◽

Phase 2 ◽

Online Data ◽

Web Based ◽

Online Tool ◽

Novel Approach ◽

Patients With Diabetes ◽

Personal Performance

Abstract Background Systematically engaging residents in large programs in quality improvement (QI) is challenging. Objective To coordinate a shared QI project in a large residency program using an online tool. Methods A web-based QI tool guided residents through a 2-phase evaluation of performance of foot examinations in patients with diabetes. In phase 1, residents completed reviews of health records with online data entry. Residents were then presented with personal performance data relative to peers and were prompted to develop improvement plans. In phase 2, residents again reviewed personal performance. Rates of performance were compared at the program and clinic levels for each phase, with data presented for residents. Acceptability was measured by the number of residents completing each phase. Feasibility was measured by estimated faculty, programmer, and administrator time and costs. Results Seventy-nine of 86 eligible residents (92%) completed improvement plans and reviewed 1471 patients in phase 1, whereas 68 residents (79%) reviewed 1054 patient charts in phase 2. Rates of performance of examination increased significantly between phases (from 52% to 73% for complete examination, P < .001). Development of the tool required 130 hours of programmer time. Project analysis and management required 6 hours of administrator and faculty time monthly. Conclusions An online tool developed and implemented for program-wide QI initiatives successfully engaged residents to participate in QI activities. Residents using this tool demonstrated improvement in a selected quality target. This tool could be adapted by other graduate medical education programs or for faculty development.

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Research on the Spatial Query Technology of Geospatial Database

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.571-572.600 ◽

2014 ◽

Vol 571-572 ◽

pp. 600-605

Author(s):

Lei Gang Sun ◽

Jian Feng Liu ◽

Quan Hong Xu

Keyword(s):

Data Model ◽

Storage Management ◽

Geospatial Data ◽

Spatial Query ◽

Oracle Spatial ◽

Practical Applications ◽

Data Query ◽

Geospatial Database ◽

Data Volume ◽

Query Model

The application requirement of Geospatial data is increasing and complex as it is getting numerous as a result of furthering study on geosciences. Based on a deeply research on Oracle Spatial storage management mechanism, this paper proposed a method that applies the graph theory to domain of optimizing spatial query of massive geographical data, and established a geospatial data query model in order to settle a problem of lower spatial query efficiency in geospatial database. Combining with the practical applications, this paper did a conventional spatial query test and a spatial query based on geospatial data model respectively. The result is that the spatial query based on geospatial data query model has a better efficiency than that on conventional method. Besides, this model can greatly improve the spatial query performance and this improvement will be increasingly apparent as the data volume increases.

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