Polygon Method Research Articles

A preliminary study on home range and daily travel distance of François’ langur in a high-altitude area

François’ langur (Trachypithecus francoisi) is an indicator species living in Karst rocky habitats. To understand the François’ langurs ecological adaptation to high-altitude habitat, we used the field tracking method to collect home-range data and daily travel distance of François’ langur at high-altitude (800–1400 m) areas of Kuankuoshui National Nature Reserve between April 2008 and March 2009. The results revealed the following: (1) according to the grid cell method, the home range of François’ langurs was estimated to be 50.7 ha. The area in the winter-spring season was larger than in the summer-autumn season (37.7 vs. 27.7 ha). According to the minimum convex polygon method by GIS, the home range of François’ langurs in the winter-spring season and the summer-autumn season was 123.5 and 68.8 ha, respectively. The whole-year home range of François’ was clearly larger than the grid cell method (140.4 vs. 50.7 ha). (2) The home range of François’ langurs had clear superposition. Langur's core areas were concentrated in three small areas, which only occupied 18.2% of the home range. (3) The langur had a short daily travel distance (230–1115 m) and significant seasonal differences. The summer-autumn season moving distances being obviously shorter than the winter-spring season (517 vs. 785 m). (4) With the decrease in the availability of food resource in winter-spring season, the home range and daily travel distance of François’ langurs significantly increased. (5) Living in the high altitudes, François' langurs tended to form a larger group (≥ 8 individuals), which is larger than other groups at lower altitude, had the larger home range, and had shorter daily travel distance. Our results indicate that colobines’ survival strategies tend to form a larger home range and shorter day-traveling distance to adapt to high-altitude and low-temperature habitat.

Preliminary Insights on the Spatial Ecology, Population Demography, and Sexual Dimorphism of the Critically Endangered Sulawesi Forest Turtle (Leucocephalon yuwonoi)

Sulawesi Forest Turtles (Leucocephalon yuwonoi) are critically endangered and endemic to the island of Sulawesi. We conducted radiotelemetry and capture–mark–recapture to study their spatial ecology, habitat selection, activity patterns, and demography in February–April and June–July, 2019. The average area occupied by 14 turtles using the minimum convex polygon (MCP) method was 0.49 ± 0.42 ha (standard deviation [SD]), whereas using the fixed 50% kernel density method averaged 0.076 ± 0.061 ha (SD). Males (mean = 0.53 ± 0.40 ha, N = 7) occupied a larger area (MCP method) than females (mean = 0.44 ± 0.46 ha, N = 7) but the difference was not statistically significant. Turtles took refuge in habitat containing significantly more canopy cover, broadleaf plant cover, and more and deeper ground cover than that in random plots. Males were predominantly active at night and females were exclusively so. We caught 25 adult females, 16 adult males, and 38 unsexed juveniles in two stream sections. Estimated population size (95% confidence intervals) in the lower stream was 17 turtles (15–28) in the wet season and 10 turtles (8–21) in the dry season. The population estimate in the upper stream was 25 (24–33) and 13 (9–28) turtles in the wet and dry seasons, respectively. Our study provides important baseline ecological data that can be used to inform future conservation and recovery programs for the species.

REDESAIN BENDUNG KEDUNG JERUK KECAMATAN PRINGAPUS KABUPATEN SEMARANG

Water is one an important element that can affect life in nature. To increase water resources, a long-term and short-term strategy is needed. Kelampok River has not been utilized optimally by the community. For this reason, it is necessary to build a weir that serves to raise water level. The planning for the construction of the Kedung Jeruk Weir in Pringapus District, Semarang Regency aims to improve the socio-economic environment in the surrounding area.The redesign is based on secondary data with other supporting data. The analyzes carried out include: hydrological analysis, planning dimensional, analysis of the stability of the weir body, and the safety of the weir body.From the results of the hydrological analysis which includes the calculation of planned rainfall using the Thiesen Polygon method and flood discharge using the Synthetic Unit Hydrograph (HSS) Gama 1 method, the water requirement for irrigation in Pringapus Village is 0.3091 m3/s and the 50th flood discharge is 206, 01 m3/s. Weir width 36 m with 0.83 m high weir. The width of the weir crest is 30.4 m, the flushing width is 3.6 m and the pillar width is 2 m (2 Pillars 1 m each). The radius of the weir of the round threshold type is 0.8 m, the stilling pool type is USBR Type III with a length of 9 m. The value of stability during normal water conditions and flood water conditions is still above the safety value so that the weir building meets the requirements and is safe.

A Method for Assessing the Thickness of Cobalt-Rich Crust on Seamounts and Its Application on the Il’ichev Guyot

Seamount cobalt-rich crusts are rich in cobalt resources and are sought after worldwide. Among different affecting parameters, crust thickness is the most important in evaluating cobalt-rich crust resources in seamounts. Generally, there are two challenges to crust thickness evaluation: firstly, due to high operating costs, most geological stations for seamount exploration have sparse sampling distributions so there are insufficient data to estimate the crust thickness distribution; secondly, a single evaluation method has advantages and disadvantages, and it is not feasible to benefit from the advantages only. These methods cannot simultaneously make full use of the sampling data in local areas, providing a more appropriate evaluation of the whole area. As a result, the estimated results cannot fully reflect the thickness distribution. Based on the thickness data of the station survey and topographic data, geostatistical units are divided, and a comprehensive crust thickness assessment scheme is established on the ArcGIS platform. To this end, the adjacent area method is applied to calculate the crust thickness within the influence range of the station. Combined with the station buffer radius and Thiessen polygon method, the crust thickness within 1.5 km of the survey station was estimated. Then the “slope–distance” Kriging interpolation method was used to calculate the crust thickness in the study area, and the crust thickness in the optimal effective radius area was given to compensate for the missing part in the first step. Finally, the geological blocks were divided using the topographic classification method, and the crust thickness of the remaining unassigned regions was estimated using the mathematical expectation method. The proposed method was applied to evaluate the Il’ichev Guyot’s crust thickness and reasonable results were achieved. It was found that the thickness estimation of the area near the station is consistent with the measured values. Since finer topographic data are used in the calculation, the thickness estimation result is more detailed. In this regard, a simple and effective calculation method was established on the ArcMap platform. The mathematical expectation estimation method of the crust thickness, based on the topographic and geomorphological classification from the perspective of the mineralization mechanism, compensates for the drawbacks of the first two methods originating from the lack of data points. The results show that the proposed method is an appropriate scheme to evaluate seamount crust thickness without comprehensive investigation.

Space use of wintering Eurasian Tree Sparrows (Passer montanus) in a semi-urban area: a radiotelemetry-based case study

Abstract Space use, which includes the home range and habitat utilisation pattern of individuals for different activities (e.g. foraging, roosting), is one of the fundamental aspects of a species ecology. Hence, knowledge on the different aspects of space use in general is essential to understand the relationship between species and their habitat. Here, we investigated the home range size (using the minimum convex polygon method; MCP) and roosting site selection, using radiotelemetry, in a sedentary passerine species, the Eurasian Tree Sparrows (Passer montanus). The study was carried out during the non-breeding period (i.e. wintering), in a semi-urban habitat where supplemental feeding was also available. We found that individuals had highly variable home ranges, both in shape and size (mean ± SD of 95% MCP: 6.89 ± 5.73 ha), the location of which was influenced by the presence of bird feeders. Roosting sites of the tracked individuals were largely consistent at an individual level, that is, all birds used the same locations for roosting during the whole tracking period, and the roosting sites of all individuals were located on buildings, except for a few rare occasions. Our results suggest that urbanised habitats can provide multiple benefits for the individuals during the winter in the form of easily accessible resources (e.g. food, roosting place), and individuals readily exploit these resources by adjusting their space use according to their availability.

A polygonal element differential method for solving two-dimensional transient nonlinear heat conduction problems

A novel polygonal element differential method (PEDM) is presented for solving two-dimensional nonlinear transient heat conduction problems for the first time. New shape functions as well as their derivatives with respect to isoparametric coordinates are derived to treat the polygonal elements with an internal node. System equations of the PBEM are formulated in terms of the governing equation and heat flux equilibrium condition, in which, a finite difference scheme is executed for calculating the transient term. Then, the nonlinearity system equations are dealt with by the Newton iterative method. Finally, examples with different structural complexities are designed to examine the property of the proposed method. The results show that the PEDM can effectively solve general two-dimensional transient nonlinear heat conduction problems with excellent accuracy and efficiency.

Mesh stiffness and dynamic response analysis of modified gear system with thin web and weight reduction holes

Though the special gear foundation structure and tooth modification are effectively applied to weight optimization and vibration control, the lack of an effective mathematical model limits the investigation of their effects. The present work develops a general polygonal approximation method for weight reduction holes, which is introduced into an analytical-finite element (AFE) method along with the decomposition method to calculate the time-varying mesh stiffness (TVMS) of modified spur gear pairs with complex foundation (thin webs and weight reduction holes). The comparisons with the traditional finite element (FE) method show the superiority of the model in calculation accuracy and efficiency. Furthermore, the actual TVMS is introduced into the dynamics model of a high-speed gear-rotor-bearing system to analyze the dynamic responses, and the effectiveness of the model is verified by experiments. The results indicate that the thin web has a greater influence on the reduction of average amplitude in stiffness than holes. The thin web significantly controls the system vibration, while the tooth modification reduces the vibration fluctuation caused by holes at medium and high speeds. The analysis and experimental results provide an important reference for gear weight optimization and vibration reduction.

A Novel Least-Squares Level Set Method by Using Polygonal Elements

In this study, we apply an artificial viscosity method to convert an unsteady level set (LS) convection equation into an unsteady LS convection-diffusion transport equation to stabilize the numerical solution of the convection term. Then a novel least-square polygonal finite element method is used to solve an unsteady LS convection-diffusion problem. The least-squares method provided good mathematical properties such as natural numerical diffusion and the positive definite symmetry of the resulting algebraic systems for the convection-diffusion and re-initialization equations. The proposed method is evaluated numerically in two different benchmark problems: a rigid body rotation of Zalesak’s disk, and a time-reversed single-vortex flow. In comparison with conventional triangular (T3) and quadrilateral (Q4) elements, polygonal elements are capable of providing greater flexibility in mesh generation for complicated problems as well as more accurate in solving the LS equations. In addition, the numerical results are also compared with the results which obtained from essentially non-oscillatory type formulations and particle LS methods. The results show that the proposed method completely matches the previously published results.

Coastline dynamics in the extreme south of Brazil and their socio-environmental impacts

A coastal inflection of ∼45 km in the extreme south of Brazil demonstrates differences in coastline behavior with areas of deposition towards north and areas of severe erosion towards south, threatening coastal occupation. These areas are believed to be controlled by the sand wave behavior of the coastline with adjacent erosion and progradation areas that have relevant alongshore sediment transport imposed by S quadrant waves. In this study, we quantified the rates of change of coastline and described the erosion and deposition controls behind it, using ultra-high-resolution orbital images and UAV (unmanned aerial vehicle) orthomosaics obtained between 2005 and 2020 for three urbanized beach sectors within the area, i.e., the São Simão, Mostardense, and Lighthouse Beaches. The rates of change of coastline were calculated using the change polygon method. The results indicated total recession values > 40 m at the Mostardense and Lighthouse beaches corresponding to a rate of ∼3 m/y. Such values characterized the coastal erosive hotspots that have not been previously identified in the area. Future coastlines were projected from the estimated annual variation rates. Buildings previously destroyed or threatened by marine/wind processes were also mapped. A continuous high-resolution and high-frequency coastal monitoring approach for the area is essential for planning the future development of these beaches to minimize and possibly avoid environmental degradation.

A new quality preserving polygonal mesh refinement algorithm for Polygonal Element Methods

Mesh adaptivity is a useful tool for efficient solution to partial differential equations in very complex geometries. In the present paper we discuss the use of polygonal mesh refinement in order to tackle two common issues: first, adaptively refine a provided good quality polygonal mesh preserving quality, second, improve the quality of a coarse poor quality polygonal mesh during the refinement process.

Time series cross-correlation between home range and number of infected people during the COVID-19 pandemic in a suburban city.

Control of human mobility is one of the most effective measures to prevent the spread of coronavirus disease 2019 (COVID-19). However, the imposition of emergency restrictions had significant negative impacts on citizens' daily lives. As vaccination progresses, we need to consider more effective measures to control the spread of the infection. The research question of this study is as follows: Does the control of home range correlate with a reduction in the number of infected people during the COVID-19 pandemic? This study aims to clarify the correlation between home range and the number of people infected with SARS-CoV-2 during the COVID-19 pandemic in Ibaraki City. Home ranges are analyzed by the Minimum Convex Polygon method using mobile phone GPS location history data. We analyzed the time series cross-correlation between home range lengths and the number of infected people. Results reveal a slight positive correlation between home range and the number of infected people after one week during the COVID-19 pandemic. Regarding home range length, the cross-correlation coefficient is 0.4030 even at a lag level of six weeks, which has the most significant coefficient. Thus, a decrease in the home range is a weak factor correlated with a reduction in the number of infected people. This study makes a significant contribution to the literature by evaluating key public health challenges from the perspective of controliing the spread of the COVID-19 infectuion. Its findings has implications for policy makers, practitioners, and urban scientists seeking to promote urban sustainability.

ANALYSIS OF LONG-TAILED MONKEY ROAMING AREA (Macaca fascicularis) IN MENIPO NATURAL TOURISM PARK, ENORAEN VILLAGE, EAST AMARASI SUBDISTRICT, KUPANG REGENCY, EAST NUSA TENGGARA PROVINCE

monkeys (Macaca fascicularis). This research was conducted at Menipo Natural Tourism Park (NTP), Enoraen Village, East Amarasi Subdistrict, Kupang Regency, East Nusa Tenggara which was conducted for 1 month, from September to October 2021. The study used Zoatrack's WebGIS method, which determined Macaca’s home range using Minimum Concex Polygon (MCP) method and core area using Kernel Utilization Distribution. Moreover, the analysis of data were conducted with statistics descriptive analysis. The results showed that the home range that has been analyzed using Minimum Convex Polygon (MCP) is 142.45 ha and this area of long-tailed monkeys (Macaca fascicularis) home range lies in almost all of the Menipo NTP area with its forest characteristics that consists of dry forests, brackish forests, and coastal forests. The results of the core area analysis using Kernel Utilization Distribution showed that the area of the core area was 53.63 Ha. The results of the core area also shows that there is one particular of core area that is often visited by long-tailed monkeys (Macaca fascicularis). This is due to the abundance of food and trees as their resting place in the Menipo NTP area.

Mesoscopic study on fracture behavior of fully graded concrete under uniaxial tension by using the phase-field method

The applicability and rationality of the phase-filed method are systematically analyzed for utilization in mesoscopic study on fully graded concrete under uniaxial tension. In this study, two kinds of mesoscopic models for fully graded concrete are generated by the polygonal characteristic parameter transformation method, and their complicated mechanical response and fracture behavior are investigated using the phase-filed method. Numerical simulations of uniaxial tensile experiments are conducted to study the effects of step time, element parameters, and meso-structures on the crack propagation and fracture mechanical response of fully graded concrete. Moreover, the computational efficiency and convergence of the phase-field method are systematically analyzed using various model setup. It is found that the numerical results of stress–strain curves and crack propagation paths are both in good agreement with the experimental results and the output from the distributed cohesive element method, and phase-field method demonstrates advantages in numerical stability. The accuracy and efficiency of this approach, which combines phase-field method and random polygonal aggregate models, are tested to study the fracture behavior of fully graded concrete.

A general analytical PBEM for solving three-dimensional transient inhomogeneous heat conduction problems with spatially varying heat generation

In the present work, a polygonal boundary element method (PBEM) for solving transient inhomogeneous heat conduction problems with spatially-varying heat generation is developed for the first time. A new general analytical method is proposed and employed in the present PBEM, by which the radial integrals associated with arbitrary spatially-varying density, specific heat, and thermal conductivity can be analytically computed, and the efficiency of the PBEM for solving the transient inhomogeneous problems can be significantly improved. The transient term is dealt with by a finite difference scheme. Three examples are designed to investigate the performance of the proposed method, and the results show that the present method could accurately and efficiently solve transient heat conduction problems with arbitrarily-varying thermal physical properties.

New practical discrete non-spherical N-body method: Validation with the Brazil nut effect

This paper presents an implementation of the contact dynamics method for discrete non-spherical particles. The algorithm can handle particles with a wide range of geometries as long as they are described in triangular surface meshes. The contact detection between particles is organized into two phases: coarse-grained and fine-grained contact detection. Specifically, different hierarchies of grids are utilized to perform fast contact detection: (a) A spatial sorting method is utilized for coarse-grained contact detection, where each non-spherical particle is represented with a corresponding bounding-sphere (b) The Polygonal Contact Method is introduced into the fine-grained contact detection phase to accurately determine the active contact areas between the interacting particles. These techniques solve the difficulties of determining the action point(s) of contact force and torque between non-spherical particles. The smooth (force-based) method is employed to calculate the contact force and torque, which is generally regarded as conforming to the actual physical process. Particularly, the non-linear Hertz and Mindlin-Deresiewicz theories are adopted to calculate the normal and tangential forces. The non-spherical Brazil nut effect under the shear vibration mode is simulated as validation by comparing with the existing experimental results. The simulation results confirmed that the convection and percolation mechanism mutually affect the nut heap's behavior and finally drive the rise of the Brazil nut from the bottom to the top layer.

Refined Urban Functional Zone Mapping by Integrating Open-Source Data

The determination of a reasonable spatial analysis unit is an essential step in urban functional zone (UFZ) division, which significantly affects the results. However, most studies on the division of functional zones are based on excessively large spatial units, such as blocks or traffic analysis zones (TAZs), which easily overlook the detailed characteristics of urban regions and introduce bias to the research conclusion. To address this issue, a refined zone segmentation method, namely, the Voronoi diagram for the polygon method, was proposed to generate refined spatial analysis units. Afterward, the functional topics of the spatial analysis unit were classified by a multiclass support vector machine (SVM) to produce the final UFZ map, where the functional topics of each spatial unit were obtained by coupling latent Dirichlet allocation (LDA). To verify the effectiveness of the proposed method, experiments were conducted in Beijing, China. The results indicated that the proposed segmentation method can generate fine-scale spatial units and provide fine-grained and higher accuracy UFZs (overall accuracy = 84%; kappa = 0.82).

Preparation of highly ionic conductive lithium phosphorus oxynitride electrolyte particles using the polygonal barrel-plasma treatment method

Herein, lithium phosphorus oxynitride (LiPON) electrolyte particles with high ionic conductivity were prepared using the polygonal barrel-plasma treatment method. Results showed that the ionic conductivity of Li3PO4 (particle size: 77 nm) was improved via the N2-plasma treatment (treatment time: 60–180 min). The maximum ionic conductivity (8.8 × 10–6 S cm–1 at room temperature) was obtained for a treatment time of 90 min, and it approximates that of amorphous LiPON films in literature. X-ray photoelectron spectroscopy of the treated samples (particle size: 29 µm) revealed the formation of LiPON: the area ratio of triply coordinated nitrogen (P–N<P2) versus doubly coordinated nitrogen (P–NP) bonds, which compose LiPON, increased as the treatment time increased to 90 min, and then decreased. The particle surface morphology hardly changed during treatment, whereas the cross-sectional observation showed that at least 320-nm amorphous LiPON layer was formed near the particle surfaces. Based on the LiPON layer thickness, it was found that amorphous LiPON particles can be obtained through N2-plasma treatment of 77 nm Li3PO4 particles. However, the formed LiPON was partially crystallized under the 120 and 180 min treatments. Thus, a variation in the formation of P–N<P2 and P–NP bonds and partial crystallization of the formed amorphous LiPON cause the treatment time dependence of ionic conductivity of the treated samples.

Automatically recognizing the semantic elements from UML class diagram images

Context:Design models are essential for multiple tasks in software engineering, such as consistency checking, code generation, and design-to-code tracing. Almost all of these works need a semantically analyzable model to represent the software architecture design, e.g., a UML class diagram. Unfortunately, many design models are stored as images and embedded in text-based documentations, impeding the usage and evolution of these models. Thus, identifying the semantic elements of design models from images is important. However, there are lots of design models with different elements in diverse representations, which ask for different approaches for semantic elements extraction. Objective:In order to grasp an overview of the commonly used design model types, we conduct a survey on both open-source communities and industry. We find that design model diagrams are usually embedded in documents as pictures (73.72%), and UML class diagrams are the most used type (55.43%). Considering that there are limited studies on automatically recognizing the semantic elements from class diagram images, we propose an approach, which we call ReSECDI. Method:ReSECDI includes our customized design for extracting UML class diagram elements based on image processing technologies. We design a rectangle clustering method for class recognition, to address the challenge that the presentation of classes may vary due to the UML constraints and tools’ styles. We design a polygonal line merging method and double-recognition-approximation method for relationship recognition to deal with the impact of low resolution on the detection. Results:We evaluate the applicability of ReSECDI on 30 images drawn by three popular UML tools and 50 diagrams collected from the open-source communities, and get promising performances. Conclusion:ReSECDI can recognize all types of semantic elements commonly used. It has well applicability and can be used to process the images drawn by the mainstream tools and stored in different resolutions.Editor’s note: Open Science material was validated by the Journal of Systems and Software Open Science Board.

Acquisition of rainfall in ungauged basins: a study of rainfall distribution heterogeneity based on a new method

High-density rainfall data is always desired to capture the heterogeneity of precipitation to accurately describe the components of the hydrological cycle. However, equipping and maintaining a high-density rain gauge network involve high costs, and the existing rain gauges are often unable to meet the density requirements. The objective of this study is to provide a new method to analyze the spatiotemporal variability of the precipitation field and to solve the problem of insufficient site density. To this end, the proper orthogonal decomposition (POD) method is proposed, which can analyze the spatial distribution characteristics of rainfall fields to solve data shortages. To demonstrate the feasibility and advantages of the proposed methodology, four districts and counties (Hongshan District, Jianli County, Sui County, and Xuanen County) in Hubei province in China were selected as case studies. The principal results are as follows. (1) The proposed method is effective in analyzing the spatiotemporal variability of the rainfall field to reconstruct rainfall processes in ungauged basins. (2) Compared with the commonly used Thiessen polygon method, the inverse distance weighting method, and the Kriging method, POD is more accurate and convenient, and the root mean squared error is reduced from 3.22, 1.83, 2.19 to 2.09; the correlation coefficients are improved from 0.60, 0.85, 0.79 to 0.89, respectively. (3) The POD method performs particularly well in simulating the peak value and the peak time and can offer a meaningful reference for analyzing the spatial distribution of rainfall.

Assessing the effective spatial characteristics of input features through physics-informed machine learning models in inundation forecasting during typhoons

This study aimed to assess the effective spatial characteristics of input features by using physics-informed, machine learning (ML)-based inundation forecasting models. To achieve this aim, inundation depth data were simulated using a numerical hydrodynamic model to obtain training and testing data for these ML-based models. Effective spatial information was identified using a back-propagation neural network, an adaptive neuro-fuzzy inference system, support vector machine, and a hybrid model combining support vector machine and a multi-objective genetic algorithm. The conventional average rainfall determined using the Thiessen polygon method, rain gauge observations, radar-based rainfall data, and typhoon characteristics were used as the inputs of the aforementioned ML models. These models were applied in inundation forecasting for Yilan County, Taiwan, and the hybrid model had the best forecasting performance. The results show that the hybrid model with crucial features and appropriate lag lengths has the best performance.