Hasil untuk "Metropolitan areas"

Rami Luisto

In this paper we analyze the Finnish road network as a graph in order to measure whether the "rurality" or "urbanity" of an area correlates with local geometrical properties of the graph. Our primary motivation is the observation that the road systems in rural areas look similar to hyperbolic graphs, while in large cities they resemble more the Cayley graph of $\mathbb{Z}^2$. We do not aim for a comprehensive analysis, but rather wish to demonstrate that this observation can be measured and analyzed through looking at various "hyperbolicity measures" of randomly sampled geodesic triangles in the road graph.

Ziyue Wang, Adhitya Marendra Kiloes, Md. Ali Akber et al.

Peri-urban areas (PUAs), as transitional zones between urban and rural regions, play a critical role in supporting food systems and agricultural livelihoods, yet they are increasingly pressured by rapid urban expansion. Reliable spatial delineation of PUAs remains challenging, as administrative boundaries often fail to capture their functional and spatial heterogeneity. This study proposes a multi-dimensional, spatially explicit framework to delineate peri-urban areas using Indonesia as a case study. Eighteen indicators representing six analytical dimensions—land use/land cover, economic, demographic, infrastructural, spatial accessibility, and landscape structure—were derived from remote sensing and GIS-based data sources and integrated into a composite scoring system using equal-weighted and AHP-weighted approaches. The framework was applied to four major cities on Java Island (Jakarta, Surabaya, Bandung, and Yogyakarta) to generate continuous peri-urban probability surfaces, which were validated using expert surveys across 25 districts in the Jakarta and Bandung metropolitan areas. The results show that the framework effectively captures the spatial heterogeneity and gradients of peri-urban areas, with the equal-weighted approach exhibiting statistically significant agreement with expert assessments (Pearson’s r = 0.517, <i>p</i> = 0.008; Spearman’s ρ = 0.522, <i>p</i> = 0.008; Kendall’s τ = 0.387, <i>p</i> = 0.008), consistently outperforming the AHP-weighted model across all validation metrics. The proposed approach provides a transferable spatial mapping framework for monitoring peri-urban dynamics in rapidly urbanizing regions using remote sensing and GIS.

Zhang Qianwei, Xi Guangliang

Against the strategic backdrop of "Digital-China" and the "Dual-Carbon" goals, the synergistic advancement of digital economy and carbon emission reduction is crucial for achieving high-quality, sustainable development. As a leading region in China's economic and digital transformation, the Yangtze River Delta (YRD) urban agglomeration provides a critical-case study for examining the complex interplay between digital growth and decarbonization. In this study, we aimed to systematically analyze the spatiotemporal-coupling characteristics and underlying influence mechanisms between the digital economy and carbon emissions in the YRD region from 2011 to 2023. Moving beyond aggregate-analysis and linear-assumptions, this study seeks to reveal the spatial heterogeneity, nonlinear-relationships, and threshold-effects to provide a nuanced empirical basis for differentiated-regional policymaking. Methodologically, we integrated the Geographically Weighted Random Forest (GWRF) model with SHapley Additive exPlanations (SHAP). We constructed comprehensive evaluation systems for both the digital economy and carbon emissions, and calculates the coupling coordination degree (D) between these two systems for 41 cities. The core analytical approach uses the GWRF model, which embeds a spatial-weight matrix into the Random Forest algorithm to simulate the spatially-varying and nonlinear effects of multiple influencing factors on the degree of coordination. Subsequently, the SHAP framework was applied to interpret the GWRF " black-box model and quantify the global-importance, directional-contribution, and potential nonlinear or threshold-behavior of each explanatory variable. This study yielded several key findings. Regarding temporal evolution, the overall coupling coordination degree of the YRD urban agglomeration shows a clear upward trend, increasing from 0.411 in 2011 to 0.505 in 2023, marking a transition from an "imminent-imbalance" to a "barely-coordinated" stage. However, this progression is not monotonic; the significant dip observed in 2021 reflects dynamic tension and potential lagged-adaptation between technological-advancement cycles and stringent emission-reduction targets. In terms of spatial patterns, a distinct hierarchical "core-corridor-periphery" radial structure has formed. Shanghai, leveraging its advanced technological foundation and institutional advantages, remains at the forefront, achieving "high-quality coordination" by 2023. The provinces of Jiangsu and Zhejiang exhibit follow-up growth, entering the "barely-coordinated" stage. In contrast, Anhui province, despite exhibiting the fastest growth rate, remains at the threshold of "imminent-imbalance," highlighting persistent regional disparities within the agglomeration. At the city level, high-coordination cores were concentrated along the Shanghai-Nanjing-Hefei-Hangzhou development axis, with coordination levels gradually diffusing along major transport corridors and weakening in northern Anhui and southwestern Zhejiang. Concerning the model validation and identification of key drivers, the GWRF model demonstrated significantly superior explanatory power and predictive accuracy compared to the standard-Random Forest model, confirming its efficacy in capturing spatial-non-stationarity. The SHAP analysis identified variables from the digital economy subsystem, specifically, the number of mobile phone subscribers, employees in information transmission and software services, and postal business volume, as important positive drivers. Their intensity-of-influence exhibited a spatial-diffusion pattern, radiating outward from core metropolitan areas to key manufacturing nodes and emerging industrial zones. Conversely, variables from the carbon emissions subsystem, particularly carbon emissions intensity and per-capita carbon emissions, act as primary inhibitors of coupling coordination. In summary, this study elucidates a dual-path mechanism, wherein the agglomeration of digital elements drives synergistic improvements, whereas high-carbon economic structures exert inhibitory pressure. This study makes substantive contributions to both the theoretical and methodological fronts. Theoretically, it provides robust empirical evidence for the complex, nonlinear-interdependencies between digital and green transitions, challenging simplistic linear-assumptions and enriching the understanding of their coupling dynamics in a regional context. Methodologically, the integrated GWRF-SHAP framework was validated as a powerful tool for dissecting high-dimensional and spatially-heterogeneous problems in urban and regional studies, offering a replicable-analytical pathway. These findings provide actionable-insights for policymakers to advocate tailored-strategies that reinforce positive digital diffusion, especially in lagging areas, while implementing targeted measures to decouple economic growth from carbon emissions in high-pressure zones. Ultimately, this approach aims to foster a more balanced and synergistic development pathway for the YRD and similar regions.

Ross D. Monaghan, Jonathan L. Marenkovic, Giuseppe C. Tettamanzi

Superconducting Quantum Interference Devices (SQUIDs), formed by incorporating Josephson junctions into loops of superconducting material, are the backbone of many modern quantum sensing systems. It has been demonstrated that, by combining multiple SQUID loops into a two-dimensional (2D) array, it is possible to fabricate ultra-high-performing Radio frequency sensors. However, to function as absolute magnetometers, current-in-use arrays require the area of each SQUID loop in the array to be incommensurate. Doing so forbids the achievement of their full potential of performance, limited only by the standard quantum limit. This is because imposing incommensurability in the areas contrasts with optimised performance in each single SQUID loop. In this work, we report that by selectively inserting bare sections of a superconducting circuit with no Josephson junctions, 2D SQUID arrays can operate as an absolute magnetometer even when no physical area spread is applied. Based on a generalisation of current available theories, a complete analytical formulation for the one-to-one correspondence between the distribution of these bare loops and what we call a synthetic area spread is unveiled. This synthetic spread represents the equivalent physical spread of incommensurate SQUID loops that you would use to obtain the absolute Voltage-Magnetic Flux response if no bare loops were in use. Our work opens the way to a broader use of this technology for the fabrication of ultra-high-performance absolute quantum sensors. Our approach is also experimentally verified by fabricating several 2D Superconducting Quantum Interference Filter (SQIF) arrays incorporating bare superconducting loops and by demonstrating that they behave in alignment with what is suggested by our theory.

Yousuke Sato, Yutaka Arai, Naoko Saitoh et al.

This study investigated factors contributing to the variation of the surface air CO _2 in summer over the Central Tokyo Metropolitan Area (TMA), one of the most densely populated areas on Earth, by using a meteorological model with a fine horizontal resolution of 500 m. A component for simulating CO _2 in the atmosphere was developed and implemented in the meteorological model. The model was validated by comparison with ground-based and aircraft measurements over the TMA. The evaluation results indicated that the model reproduced the CO _2 concentration and CO _2 daily variation measured by the observations well. The meteorological variation had large effects on the CO _2 variation. The small-scale circulation around TMA contributed to the multi-day variability in the CO _2 concentration over the Central TMA. The CO _2 concentration over the Central TMA tended to be high and low when the northerly and southerly wind was dominant, respectively. The sensitivity experiments clarified the contributions of the ecosystem respiration and photosynthesis, local surface emissions, and large point source emissions to the daily mean concentration of simulated CO _2 over the Central TMA. Our results demonstrate that regional models with fine grid resolution enable us to simulate various processes related to CO _2 variations on a city scale, which is required to refine anthropogenic emissions from urban areas.

Ruxandra Sava-Rosianu, Guglielmo Campus, Vlad Tiberiu Alexa et al.

Background: Oral diseases represent a constant burden for health care and socio-economic systems as they are correlated to other non-communicable diseases. The aim of the proposed intervention is to test the effect of daily tooth brushing and oral health education on the oral health status of kindergarten children. Methods: The protocol will be conducted based on a previous epidemiological survey and conducted over 24 months; it has been developed on different levels. Dental hygienists will receive specific training to deliver oral health promotion to children and nursery educators. Training will focus on tailoring key messages to the specific age at visit; this will be outlined in the care pathway and offer practical preparation for delivering interventions and a toothpaste/toothbrush scheme. It will also, involving involve offering free daily tooth brushing to every 4–6-year-old child attending nursery. Data will be collected in four kindergartens in the capital or metropolitan areas, two kindergartens each in two large cities, and one kindergarten each in four villages from different geographic areas. Procedures used to assess the outcomes of each activity will be tailored to specific outcomes. Daily tooth-brushing activities will be monitored using qualitative research. A cost analysis including the distribution of necessary materials and correct delivery of products that shows price trends and percentage differences over the time span as well as consumer price index evaluation for the given time span will be conducted. Clinical outcomes will be evaluated using the caries incidence rate; this will be calculated for each tooth as the unit of analysis and evaluated using a multi-step approach. Discussion: Downstream oral health prevention interventions, like clinical prevention and oral health promotion, aim to enhance children’s quality of life. The program’s goal is to progress towards upstream interventions for a more significant impact.

Anselme Ndikumana, Kim Khoa Nguyen, Mohamed Cheriet

Internet access in rural areas should be improved to support digital inclusion and 5G services. Due to the high deployment costs of fiber optics in these areas, Fixed Wireless Access (FWA) has become a preferable alternative. Additionally, the Open Radio Access Network (O-RAN) can facilitate the interoperability of FWA elements, allowing some FWA functions to be deployed at the edge cloud. However, deploying edge clouds in rural areas can increase network and energy costs. To address these challenges, we propose a closed-loop system assisted by a Digital Twin (DT) to automate energy-aware O-RAN based FWA resource management in rural areas. We consider the FWA and edge cloud as the Physical Twin (PT) and design a closed-loop that distributes radio resources to edge cloud instances for scheduling. We develop another closed-loop for intra-slice resource allocation to houses. We design an energy model that integrates radio resource allocation and formulate ultra-small and small-timescale optimizations for the PT to maximize slice requirement satisfaction while minimizing energy costs. We then design a reinforcement learning approach and successive convex approximation to address the formulated problems. We present a DT that replicates the PT by incorporating solution experiences into future states. The results show that our approach efficiently uses radio and energy resources.

Judith Sáinz-Pardo Díaz, María Castrillo, Juraj Bartok et al.

The increasing generation of data in different areas of life, such as the environment, highlights the need to explore new techniques for processing and exploiting data for useful purposes. In this context, artificial intelligence techniques, especially through deep learning models, are key tools to be used on the large amount of data that can be obtained, for example, from weather radars. In many cases, the information collected by these radars is not open, or belongs to different institutions, thus needing to deal with the distributed nature of this data. In this work, the applicability of a personalized federated learning architecture, which has been called adapFL, on distributed weather radar images is addressed. To this end, given a single available radar covering 400 km in diameter, the captured images are divided in such a way that they are disjointly distributed into four different federated clients. The results obtained with adapFL are analyzed in each zone, as well as in a central area covering part of the surface of each of the previously distributed areas. The ultimate goal of this work is to study the generalization capability of this type of learning technique for its extrapolation to use cases in which a representative number of radars is available, whose data can not be centralized due to technical, legal or administrative concerns. The results of this preliminary study indicate that the performance obtained in each zone with the adapFL approach allows improving the results of the federated learning approach, the individual deep learning models and the classical Continuity Tracking Radar Echoes by Correlation approach.

Noah Goodall

Region-wide restrictions on personal vehicle travel have a long history in the United States, from riot curfews in the late 1960s, to travel bans during snow events, to the 2013 shelter-in-place "lockdown" during the search for the perpetrator of the Boston Marathon bombing. Because lockdowns require tremendous resources to enforce, they are often limited in duration or scope. The introduction of automated driving systems may allow governments to quickly and cheaply effect large-area lockdowns by jamming wireless communications, spoofing road closures on digital maps, exploiting a vehicle's programming to obey all traffic control devices, or coordinating with vehicle developers. Future vehicles may lack conventional controls, rendering them undrivable by the public. As travel restrictions become easier to implement, governments may enforce them more frequently, over longer durations and wider areas. This article explores the practical, legal, and ethical implications of lockdowns when most driving is highly automated, and provides guidance for the development of lockdown policies.

Jennifer Bratburd, Samuel Younkin, Jonathan Patz et al.

Background The prevalence of chronic disease in the US adult population varies across socioeconomic groups in the USA where approximately six in 10 adults have a chronic condition. Walking or cycling reduces the risk to many of these diseases and is influenced by the built environment, accessibility, and safety. Methods We performed multivariate logistic and linear regression on the Health-Oriented Transportation model parameters using the 2009 and 2017 US National Household Transportation surveys, restricted to adults in major metropolitan areas. Model covariates included socioeconomic and environmental characteristics. Results Using odds ratios (OR) adjusted for model covariates, we observe several significant variables in 2009 and 2017. Residents of households with no cars were more likely to walk or cycle than those with two cars; OR=5.4 (4.8, 6.0). Residents of households in a census block with population density greater than 2,5000 persons/square mile were more likely to walk or cycle than those with a population density of 2000–3999; OR=2.6 (2.3, 2.8). Individuals with a graduate or professional degree were more likely to walk or cycle than those with a high school degree; OR=2.1 (1.9, 2.2). Individuals that self-report as Black or African American, or Asian are less likely to walk or cycle than White; OR=0.60 (0.56, 0.66), OR=0.70 (0.65, 0.75). The proportional increase in all-cause mortality from estimated reductions in physical activity for African American, Asian, and Hispanic populations were 1.0%, 0.7%, 0.8%, respectively. Conclusions Access to automobiles and the surrounding population density are primary factors in the decision to walk or cycle. After adjusting for these and other factors, members of low-income, low-education, Black or African American, and Asian populations in US metropolitan areas are less likely to walk or cycle than high-income, high-education, or White populations and the discrepancy in physical activity is likely to contribute to health inequity.

Xiuli He, Wenxin Liu

Abstract Farmland transfer is a critical component in facilitating agricultural scale management and improving agricultural production efficiency. This study examines the spatial distribution of farmland transfer in China and identifies the factors influencing it, offering valuable guidance for advancing China’s farmland transfer practices. Through the application of mathematical statistics and GIS spatial analysis, the study investigates changes in spatial patterns related to the scale, rate, mode, and recipients of farmland transfer across China's 30 provinces from 2015 to 2020. Geographical detectors are also employed to identify the key factors influencing the extent and pace of farmland transfer. The study reveals that between 2015 and 2020, China's farmland transfer area increased from 29,789 to 37,638 million hectares. Provinces with abundant farmland resources generally experienced larger farmland transfers, while economically developed regions and major grain-producing areas saw higher rates of farmland transfers. The predominant mode of farmland transfer in China was leasing (subcontracting), accounting for over 80% of the total transferred area. Large-scale grain growers and family farms were significant participants in farmland transfers, acquiring approximately 60.1% of the transferred lands, followed by professional cooperatives (21.5%), enterprises (10.4%), and other entities (7.9%). Key factors influencing the farmland transfer area include the "regional farmland area", the "proportion of family farms supported by loans", and the "proportion of non-agricultural population", with explanatory powers of 0.663, 0.319, and 0.225, respectively. Notably, there is a substantial interaction between the "regional farmland area" and factors such as the "proportion of family farms supported by loans" and the "grain yield per unit area", with explanatory powers reaching 0.957 and 0.901, respectively. These findings offer valuable insights for promoting farmland transfer in agriculturally rich regions. Factors affecting the farmland transfer rate include "grain yield per unit area", "GDP per capita", and the "proportion of non-agricultural population", each with an explanatory power above 0.500. Moreover, their interactive explanatory powers with other indicators exceed 0.600, indicating that provinces with high agricultural productivity or economic development levels are more likely to undergo farmland transfer. The paper concludes by proposing strategies and recommendations to promote farmland transfer in both "large agricultural areas" and "metropolitan suburbs."

Christian M. ROGERSON

Territorial administrative restructuring and the redrawing of municipal boundaries was undertaken in South Africa to address the apartheid legacy of major social, economic and spatial inequalities. A significant consequence of territorial administrative restructuring was that the boundaries of certain South African metropolitan areas were expanded such that they incorporate vast rural geographies. These spaces pose particular challenges for metropolitan planning. The aim in this paper is to examine the resultant planning challenges which confront South Africa’s extended metropolitan spaces. Among several consequences was the imperative for metropolitan authorities to build new competences in order to plan and manage these added rural spaces as well as the peri-urban spaces. The analysis is contextualised within an international literature on planning in extended metropolitan spaces and of peri-urban spaces.

Matteo Straccamore, Matteo Bruno, Bernardo Monechi et al.

Over the years, the growing availability of extensive datasets about registered patents allowed researchers to better understand technological innovation drivers. In this work, we investigate how the technological contents of patents characterise the development of metropolitan areas and how innovation is related to GDP per capita. Exploiting worldwide data from 1980 to 2014, and through network-based techniques that only use information about patents, we identify coherent distinguished groups of metropolitan areas, either clustered in the same geographical area or similar from an economic point of view. We also extend the concept of coherent diversification to patent production by showing how it represents a decisive factor in the economic growth of metropolitan areas. These results confirm a picture in which technological innovation can lead and steer the economic development of cities, opening, in this way, the possibility of adopting the tools introduced here to investigate the interplay between urban development and technological innovation.

Uchechukwu L. Osuagwu, Matthew Xu, Milan K. Piya et al.

Abstract Background Long stay in intensive care unit (ICU) is associated with poor outcomes, particularly in people with diabetes. It increases the financial burden of care and this is a challenge to the South Western Sydney region, which is already a hotspot for diabetes in Australia. This study compared ICU admission characteristics of people with and without diabetes and the factors associated with long ICU stay among patients admitted to public hospitals in this metropolitan health district from 2014 to 2017. Methods Cross-sectional datasets on 187,660, including all ICU admissions in the New South Wales Admitted Patient Data Collection (APDC) from June 2014 – July 2017 in public hospital were extracted. Data on demographic and health insurance status, primary admission diagnosis using ICD-10, comorbidities including death among hospital inpatients aged ≥18 years residing in SWS were analysed. The ICU length of stay was the outcome variable and were classified into short stay (≤48 h) and long stay (> 48 h), and were examined against potential confounding factors using bivariate and multiple logistic regression analyses. Results Our results showed higher ICU admissions in patients with diabetes than in those without diabetes (5% vs. 3.3%, P < 0.001) over three years. The median and interquartile range (IQR) of length of the ICU stay were similar in both groups [diabetes: 40 h, IQR = 16–88 h vs. non-diabetes: 43 h, IQR = 19–79 h]. The prevalence of long ICU stays among people with and without diabetes were 44.9% [95% CI 42.1, 47.7%] and 43.6% [95% CI 42.2, 44.9%], respectively. For both groups, increased odds of long ICU stay were associated with death and circulatory system disease admissions, while musculoskeletal disease admissions were associated with lower risk of long ICU stay. In the non-diabetes group, male sex, nervous system disease admissions and living in peri-urban areas were associated with higher odds of long ICU stay. Conclusions The rate of ICU admissions among inpatients remain higher in people with diabetes. One in every two admissions to ICU had a long stay. Additional care for those admitted with circulatory system diseases are needed to reduce long ICU stay related deaths in SWS.

Sang Jun Eun

OBJECTIVES This study aimed to describe the regional avoidable mortality trends in Korea and examine the trends in avoidable mortality disparities between the Seoul Capital Area and non-Seoul-Capital areas, thereby exploring the underlying reasons for the trend changes. METHODS Age-standardized mortality rates from avoidable causes between 2001-2020 were calculated by region. Regional disparities in avoidable mortality were quantified on both absolute and relative scales. Trends and disparities in avoidable mortality were analyzed using joinpoint regression models. RESULTS Avoidable, treatable, and preventable mortalities in Korea decreased at different rates over time by region. The largest decreases were in the non-Seoul-Capital non-metropolitan area for avoidable and preventable mortality rates and the non-Seoul-Capital metropolitan area for treatable mortality rates, despite the largest decline being in the Seoul Capital Area prior to around 2009. Absolute and relative regional disparities in avoidable and preventable mortalities generally decreased. Relative disparities in treatable mortality between areas widened. Regional disparities in all types of mortalities tended to improve after around 2009, especially among males. In females, disparities in avoidable, treatable, and preventable mortalities between areas improved less or even worsened. CONCLUSIONS Trends and disparities in avoidable mortality across areas in Korea seem to have varied under the influence of diverse social changes. Enhancing health services to underserved areas and strengthening gender-oriented policies are needed to reduce regional disparities in avoidable mortality.

Md Mashfiq Rizvee, Md Amiruzzaman, Md Rajibul Islam

In this study, we present both data mining and information visualization techniques to identify accident-prone areas, most accident-prone time, day, and month. Also, we surveyed among volunteers to understand which visualization techniques help non-expert users to understand the findings better. Findings of this study suggest that most accidents occur in the dusk (i.e., between 6 to 7 pm), and on Fridays. Results also suggest that most accidents occurred in October, which is a popular month for tourism. These findings are consistent with social information and can help policymakers, residents, tourists, and other law enforcement agencies. This study can be extended to draw broader implications.

Isao Sauzedde

We give asymptotic estimations on the area of the sets of points with large Brownian winding, and study the average winding between a planar Brownian motion and a Poisson point process of large intensity on the plane. This allows us to give a new definition of the Lévy area which does not rely on approximations of the Brownian path.

Stefan J. Hofmeister, Astrid M. Veronig, Stefaan Poedts et al.

The relationship between the peak velocities of high-speed solar wind streams near Earth and the areas of their solar source regions, i.e., coronal holes, has been known since the 1970s, but it is still physically not well understood. We perform 3D magnetohydrodynamic (MHD) simulations using the European Heliospheric Forecasting Information Asset (EUHFORIA) code to show that this empirical relationship forms during the propagation phase of high-speed streams from the Sun to Earth. For this purpose, we neglect the acceleration phase of high-speed streams, and project the areas of coronal holes to a sphere at 0.1 au. We then vary only the areas and latitudes of the coronal holes. The velocity, temperature, and density in the cross section of the corresponding highspeed streams at 0.1 au are set to constant, homogeneous values. Finally, we propagate the associated high-speed streams through the inner heliosphere using the EUHFORIA code. The simulated high-speed stream peak velocities at Earth reveal a linear dependence on the area of their source coronal holes. The slopes of the relationship decrease with increasing latitudes of the coronal holes, and the peak velocities saturate at a value of about 730 km/s, similar to the observations. These findings imply that the empirical relationship between the coronal hole areas and high-speed stream peak velocities does not describe the acceleration phase of high-speed streams, but is a result of the high-speed stream propagation from the Sun to Earth.

Isabel M. del Águila, José del Sagrado, Joaquín Cañadas

Society today cannot run without software and by extension, without Software Engineering. Since this discipline emerged in 1968, practitioners have learned valuable lessons that have contributed to current practices. Some have become outdated but many are still relevant and widely used. From the personal and incomplete perspective of the authors, this paper not only reviews the major milestones and areas of interest in the Software Engineering timeline helping software engineers to appreciate the state of things, but also tries to give some insights into the trends that this complex engineering will see in the near future.

Yang Li

The area query, to find all elements contained in a specified area from a certain set of spatial objects, is a very important spatial query widely required in various fields. A number of approaches have been proposed to implement this query, the best known of which is to obtain a rough candidate set through spatial indexes and then refine the candidates through geometric validations to get the final result. When the shape of the query area is a rectangle, this method has very high efficiency. However, when the query area is irregular, the candidate set is usually much larger than the final result set, which means a lot of redundant detection needs to be done, thus the efficiency is greatly limited. In view of this issue, we propose a method of iteratively generating candidates based on Voronoi diagrams and apply it to area queries. The experimental results indicate that with our approach, the number of candidates in the process of area query is greatly reduced and the efficiency of the query is significantly improved.