Ellipse Model Research Articles

Spatial-temporal characteristics of the coupling coordination of social security and economic development in China during 2002–2018

Clarifying the relationship between social security and economic development is helpful to realize the sustainable social security system and the stable function of sustainable economic development. In this paper, the entropy method, coupling coordination degree, standard deviation ellipse model, and spatial autocorrelation were used to study the spatial-temporal characteristics of coupling coordination of social security and economic development in China from 2002 to 2018. The results indicate that the relationship between social security and economic development in China has been gradually strengthened in the process of mutual adaptation and common development. The benign interaction between the two was unstable, though the coupling coordination degree gradually transitioned to the primary coupling coordination type. Besides, from a spatial perspective, first, the coupling coordination degree of social security and economic development in China contracted in the east-west and north-south directions, and the coupling coordination clustered in the central region in this period; second, the coupling coordination degree generally presented a positive spatial autocorrelation, and regions with similar coupling coordination degrees were in a state of agglomeration; finally, the hot spots clumped together to form a continuous area in the eastern coastal area while the cold spots expanded toward the northwest and northeast. Furthermore, the random distribution areas exhibited a trend of contraction.

Comparative study on the deviation characteristics of post-earthquake intensity evaluation based on two intensity attenuation relationship models

We collect the isoseismal data of 488 earthquakes in western China and 182 earthquakes in eastern China after 1900. The least square method is used to establish two models of the seismic intensity attenuation relationship partitions in China, based on the major and minor axis ellipse models, and the area and the major axis radius, respectively. The two models are applied to the calculation of the intensity circle of the earthquake events with a magnitude MS ​≥ ​5.0 from 2008 to 2019, and the actual intensity is compared with the model intensity value as an indicator to verify the consistency between the actual intensity and the value from the empirical statistical model. Three real earthquake results are selected to calculate the major and minor axis and area of the ellipse using the two intensity attenuation relationship models. After comparison, we summarize the deviation characteristics of the intensity value, and put forward corresponding improvement suggestions.

The Forming Profile Model for Cold Metal Transfer and Plasma Wire-Arc Deposition of Nickel-Based Alloy

The effect of process parameters on the forming profile of nickel-based alloy deposited by plasma and cold metal transfer (CMT) wire-arc deposition was comparatively studied. The plasma arc welding (PAW) deposition presented good wettability and high dilution rate, while CMT deposition showed the opposite. The ellipse and parabola function models for single weld bead forming profile were established by MATLAB software. The results showed that the ellipse function model had the higher similarity with the profile features of PAW and CMT deposition in terms of area error and matching degree. The single-layer multi-bead (SLMB) and single-bead multi-layer (SBML) forming profile of PAW and CMT were predicted, respectively, according to the size of wetting angle and the length of ellipse axis. There was an incomplete fusion defect at the weld toe when depositing SLMB by CMT, but not by PAW. In the SBML experiment, two sides of the PAW deposition layer were both smoother than those of the CMT deposition layer.

Macroseismic intensity attenuation in western China

Macroseismic intensity data play an important role in seismic hazard analysis and in developing reliable earthquake loss models. This paper adopts an ellipse model to predict the macroseismic intensity attenuation in both the long-axis and the short-axis directions based on 136 earthquakes recorded throughout western China during 1970–2012. The geometric spreading and energy release of seismic waves are considered in the models proposed in this study. The proposed relation describes the macroseismic intensity simply as a function of the surface wave magnitude, source-to-site distance, and focal depth. This study adopts the focal depth that is not often considered in the current intensity prediction equations in China and uses different functional forms in the long- and short-axis directions. Based on residual analysis and evaluation, a more suitable macroseismic intensity predictive equation was established for western China, and it was compared and discussed with macroseismic intensity prediction equations of other researchers.

1998年以来长江经济带旅游生态安全时空格局演化及趋势预测

PDF HTML阅读 XML下载 导出引用 引用提醒 1998年以来长江经济带旅游生态安全时空格局演化及趋势预测 DOI: 10.5846/stxb201912022599 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41771162）；湖南省国内一流培育学科建设项目资助（地理学-5010002） Spatio-temporal pattern evolution and trend prediction of tourism ecological security in the Yangtze River Economic Belt since 1998 Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:旅游生态安全是旅游业可持续发展的基础。基于DPSIR （驱动力-压力-状态-影响-响应，Driving force-Pressure-State-Impact-Response）模型，构建长江经济带旅游生态安全评价指标体系，综合采用熵权TOPSIS （逼近理想解排序法，Technique for Order Preference by Similarity to an Ideal Solution）法、空间变差模型、标准差椭圆模型、灰色动态模型等方法分析长江经济带1998-2017年旅游生态安全水平的时空动态演变特征，并对其未来空间分布格局进行合理预测。研究发现：（1）长江经济带旅游生态安全水平均值为0.305，综合指数由0.207上升至0.439，呈稳步提升态势，安全状态由较不安全级上升至临界安全级；（2）经济带旅游生态安全为不安全级和较不安全级的省区数量逐渐减少，而处于临界安全级的省区数量持续增加，整体正介于由中低级向高级过渡的关键阶段；（3）旅游生态安全空间变异程度不断增强，空间分异特征显著，整体呈现出"东部 > 西部 > 中部"的空间演变格局，同时低值区域具有明显的西南迁移现象；（4）旅游生态安全空间分布格局呈东北-西南走向，移动路径呈"西北→东北→东南"变化趋势，空间分布范围经历了"分散-集聚"的过程。预测结果显示：2018-2030年旅游生态安全重心将向东北方向移动，空间分布格局在东西和南北方向上均呈敛缩态势，空间溢出效应不明显。 Abstract:Tourism ecological security is the basis of sustainable development of tourism. Based on Driving force-Pressure-State-Impact-Response (DPSIR) model, an evaluation index system for tourism ecological security in the Yangtze River Economic Belt is constructed. Meanwhile, a combination of entropy weight TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) method, spatial variation model, standard deviation ellipse model, grey dynamic model and other methods is adopted to analyze and characterize the spatio-temporal dynamics of security level for tourism ecology along the Yangtze River Economic Belt during the period between 1998 and 2017, further with which a sensible prediction is made for its future pattern of spatial distribution. The results are as follows: (1) The average level of tourism ecological security in the Yangtze River Economic Belt is 0.305, with the comprehensive indicator increases from 0.207 to 0.439 in a status of stable improving. The security level raises from less safety grade to critical safety grade. (2) The number of provinces with unsafe grade and less safe grade for tourism ecological security gradually decreases while that with critical safety grade increases. Overall, it is at the critical stage of transition from middle and low level to high level. (3) The spatial variation degree of tourism ecological security keeps increasing with prominently spatial difference features. The overall spatial evolution pattern appears eastern > western > central tendency. At the same time, the low value area obviously migrates to the southwest. (4) The spatial distribution of tourism ecological security indicates northeast-southwest tendency, while the trajectory of gravity center presents the variational tendency of northwest→northeast→southeast. Spatial distribution range is distributed first and then gathered. The prediction results show that the gravity center of tourism ecological security will move to the northeast while the spatial distribution range will shrink in the east-west and north-south directions in 2018-2030. Therefore, the spatial spillover effect is not obvious. 参考文献 相似文献 引证文献

Non-Anchor-Based Vehicle Detection for Traffic Surveillance Using Bounding Ellipses

Cameras for traffic surveillance are usually pole-mounted and produce images that reflect a birds-eye view. Vehicles in such images, in general, assume an ellipse form. A bounding box for the vehicles usually includes a large empty space when the vehicle orientation is not parallel to the edges of the box. To circumvent this problem, the present study applied bounding ellipses to a non-anchor-based, single-shot detection model (CenterNet). Since this model does not depend on anchor boxes, non-max suppression (NMS) that requires computing the intersection over union (IOU) between predicted bounding boxes is unnecessary for inference. The SpotNet that extends the CenterNet model by adding a segmentation head was also tested with bounding ellipses. Two other anchor-based, single-shot detection models (YOLO4 and SSD) were chosen as references for comparison. The model performance was compared based on a local dataset that was doubly annotated with bounding boxes and ellipses. As a result, the performance of the two models with bounding ellipses exceeded that of the reference models with bounding boxes. When the backbone of the ellipse models was pretrained on an open dataset (UA-DETRAC), the performance was further enhanced. Several data augmentation schemes also improved the performance of the proposed models. As a result, the best mAP score of a CenterNet exceeds 0.95 when augmenting heatmaps with bounding ellipses.

Focusing Nonparallel-Track Bistatic SAR Data Using Modified Frequency Extended Nonlinear Chirp Scaling

Unsynchronization of the separate transmit–receive beams makes it a challenging task to obtain high-quality images for nonparallel-track bistatic synthetic aperture radar (NP-BiSAR). To accommodate this issue, we propose an imaging configuration where the receiver’s beam follows the transmitter’s one actively by adjusting the squint angle of receiver. And a frequency extended nonlinear chirp scaling (FENLCS) algorithm is modified to cope with new effects introduced by the innovative configuration, which is based on an improved quadratic ellipse model. Based on the new model, some innovative improvements on image formation are made, including a residual azimuth-dependent high-order range cell migration correction (ADH-RCMC) and a rederived FENLCS that takes highly varying Doppler centroid into consideration, which contribute to better imaging quality. Simulation results validate the effectiveness of the proposed configuration and algorithm.

LiDAR point’s elliptical error model and laser positioning for autonomous vehicles

Automated driving is the development trend of vehicle driving, and laser LiDAR is the high-precision positioning sensor that automated driving relies on most. Laser positioning mainly depends on the relative orientation from the detected environment features to the self-vehicle. However, when there are multiple detected features that carry different orientation information, all the data are redundant. In order to improve the vehicle’s positioning accuracy, two laser point evaluation models were put forward. First, based on the plane area analysis method, a spot error model was proposed, and the error distribution with the incidence angle and scanning distance was obtained. Second, the laser point’s position approximately obeys the Gaussian distribution, the laser’s stereo error ellipsoid model was established, and the laser point’s probability volume was calculated through the probability integration. Third, the point cloud features were extracted by a proposed roughness method, the point accuracy was evaluated by the proposed spot and stereo error models, and the points’ relative weights were recalculated in the laser signal’s positioning process. Finally, in order to verify the laser point’s evaluation positioning method, the simulation and experimental verifications were conducted. The results show that the evaluation method based on the error ellipse models can improve the laser positioning accuracy effectively.

Anthropometric Landmarks Extraction and Dimensions Measurement Based on ResNet

Anthropometric dimensions can be acquired in 2D images by landmarks. Body shape variance causes low accuracy and bad robustness of landmarks extracted, and it is difficult to determine the position of axis division point when dimensions are calculated by the ellipse model. In this paper, landmarks are extracted from images by convolutional neural network instead of the gradient of body outline. A general multi-ellipse model is proposed, the anthropometric dimensions are obtained from the length of different elliptical segments and the position of axis division point is determined by thickness–width ratio of body parts. Finally, an evaluation is completed based on 87 subjects, in which it turns out that the average accuracy of our method for identifying landmarks is 96.6%, when the number of rotation angles is 2, the three main dimensional errors calculated by our model are smaller than existing method, and the errors of other dimensions are also within the margin of error for garment measuring.

GIS-based approaches on the accessibility of referral hospital using network analysis and the spatial distribution model of the spreading case of COVID-19 in Jakarta, Indonesia

BackgroundThe outbreak of the novel coronavirus (COVID-19) has rapidly spread, causing million confirmed cases, thousands of deaths, and economic losses. The number of cases of COVID-19 in Jakarta is the largest in Indonesia. Furthermore, Jakarta is the capital city of Indonesia which has the densest population in the country. There is need for geospatial analysis to evaluate the demand in contrast to the capacity of Referral Hospitals and to model the spreading case of Covid-19 in order to support and organize an effective health service.MethodsWe used the data from local government publicity for COVID-19 as trusted available sources. By using the verifiable data by observation from the local government, we estimated the spatial pattern of distribution of cases to estimate the growing cases. We performed service area and Origin-Destination (OD) Cost Matrix in support to existing referral hospital, and to create Standard Deviational Ellipse (SDE) model to determine the spatial distribution of COVID-19.ResultsWe identified more than 12.4 million people (86.7%) based on distance-based service area, live in the well served area of the referral hospital. A total 2637 positive-infected cases were identified and highly concentrated in West Jakarta (1096 cases). The results of OD cost matrix in a range of 10 km show a total 908 unassigned cases from 24 patient’s centroid which was highly concentrated in West Jakarta.ConclusionsOur results indicate the needs for additional referral hospitals specializing in the treatment of COVID-19 and spatial illustration map of the growth of COVID-19′ case in support to the implementation of social distancing in Jakarta.

An improved bootstrap method introducing error ellipse for numerical analysis of fatigue life parameters

PurposeThe purpose of this paper is to introduce error ellipse into the bootstrap method to improve the reliability of small samples and the credibility of the S-N curve.Design/methodology/approachBased on the bootstrap method and the reliability of the original samples, two error ellipse models are proposed. The error ellipse model reasonably predicts that the discrete law of expanded virtual samples obeys two-dimensional normal distribution.FindingsBy comparing parameters obtained by the bootstrap method, improved bootstrap method (normal distribution) and error ellipse methods, it is found that the error ellipse method achieves the expansion of sampling range and shortens the confidence interval, which improves the accuracy of the estimation of parameters with small samples. Through case analysis, it is proved that the tangent error ellipse method is feasible, and the series of S-N curves is reasonable by the tangent error ellipse method.Originality/valueThe error ellipse methods can lay a technical foundation for life prediction of products and have a progressive significance for the quality evaluation of products.

Coupling Coordination Relationship between Urban Sprawl and Urbanization Quality in the West Taiwan Strait Urban Agglomeration, China: Observation and Analysis from DMSP/OLS Nighttime Light Imagery and Panel Data

Urban sprawl is the most prominent characteristic of urbanization, and increasingly affects local and regional sustainable development. The observation and analysis of urban sprawl dynamics and their relationship with urbanization quality are essential for framing integrative urban planning. In this study, the urban areas of the West Taiwan Strait Urban Agglomeration (WTSUA) were extracted using nighttime light imagery from 1992 to 2013. The spatio-temporal characteristics and pattern of urban sprawl were quantitatively analyzed by combining an urban expansion rate index and a standard deviation ellipse model. The urbanization quality was assessed using an entropy weight model, and its relationship with urban sprawl was calculated by a coupling coordination degree model. The results showed that the urban area in the WTSUA experienced a significant increase, i.e., 18,806.73 km2, during the period 1992–2013. The central cities grew by 11.08% and noncentral cities by 27.43%, with a general uneven city rank-size distribution. The urban sprawl showed a circular expansion pattern, accompanied by a gradual centroid migration of urban areas from the southeast coast to the central-western regions. The coupling coordination level between urban expansion and urbanization quality increased from serious incoordination in 1992 to basic coordination in 2013. Dual driving forces involving state-led policies and market-oriented land reform had a positive influence on the harmonious development of urban sprawl and urbanization quality of the WTSUA. This research offers an effective approach to monitor changes in urban sprawl and explore the coupling coordination relationship between urban sprawl and urbanization quality. The study provides important scientific references for the formulation of future policies and planning for sustainable development in urban agglomerations.

Plaučių navikų ilgosios ašies ir tūrių pokyčio palyginimas vertinant atsaką į gydymą

Plečiantis plaučių vėžio (PV) gydymo metodams ir galimybėms, kasdienėje klinikinėje praktikoje vis dažniau susiduriama su taikomų naviko atsako į gydymą vertinimo metodikų ribotumo ir tobulinimo klausimais. Standartizuota solidinių navikų atsako vertinimo metodika RECIST (angl. Response Evaluation Criteria in Solid Tumours) 1.1 ne visais atvejais gali užtikrinti ankstyvą progresuojančios ligos nustatymą. Tyrimo tikslas. Išanalizuoti išmatuojamų navikų matmenų ir tūrių pokyčių skirtumus, vertinant PV atsaką į gydymą kompiuterinės tomografijos (KT) vaizduose. Tyrimo metodai. Retrospektyviai įvertinti 2016–2019 m. įprastai atliktų KT tyrimų duomenys. Atrankos kriterijai: verifikuotas nesmulkių ląstelių PV, KT tyrimas atliktas prieš gydymą ir du KT tyrimai gydant; plaučiuose nustatytas bent vienas išmatuojamas navikinis darinys. Matuotas navikinio darinio ilgosios ašies matmuo (IA) ir tūris pagal elipsės (VT) ir sferos modelius (VS). Matavimai atlikti rankiniu ir pusiau automatiniu būdu, naudojant VitreaWorkstation™ CAD programinę įrangą. Dydžių pokyčiai vertinti remiantis RECIST 1.1 kategorijomis: progresuojanti liga (PL), dalinis atsakas ir stabili liga. Rezultatai. Tyrime analizuoti 125 pacientų duomenys. Išmatuoti 145 navikiniai dariniai ir įvertintas jų atsakas į gydymą. Nustatytas labai stiprus ryšys tarp IA ir VT prieš gydymą ir gydant (atitinkamai r=0,921, I r=0,937, II r=0,920). Vertinant VT pokyčius I ir II kontrolinių tyrimų vaizduose, PL nustatyta dažniau nei vertinant IA pokyčius, atitinkamai – 13,8 proc. ir 6,9 proc. Remiantis VT padidėjimu, I kontroliniame tyrime nustatytas PL dažnis 36,6 proc. (n=53) atitiko IA II kontroliniame tyrime nustatytą PL dažnį 35,9 proc. (n=52). Išvada. Nustatytas labai stiprus ryšys tarp naviko IA ir VT. Naviko VT padidėjimas gali būti jautresnis būdas įvertinti PL PV sergantiems pacientams.

Surrogate model-based reliability analysis for structural systems with correlated distribution parameters

Uncertainties are usually modeled by random variables, and the values of distribution parameters are estimated from the collected samples. In practical engineering, point and interval samples are possibly available for the estimation of distribution parameters; then, their values are intervals instead of point values. In view of the fact that all distribution parameters are estimated from the same set of samples, they must be correlated rather than mutually independent. In this study, the correlation among interval distribution parameters is considered and modeled using ellipse models, and the Monte Carlo simulation (MCS)-based reliability method for correlated distribution parameters, denoted as D–MCS, is first proposed. Performance functions are usually implicit functions involving simulation that are expensive-to-evaluate evaluate in real applications; hence, an efficient adaptive surrogate model-based reliability method for structural systems with correlated interval distribution parameters is proposed to reduce computational burden. A new and efficient learning function based on the U function is developed to adaptively add the best new training samples at each iteration. The corresponding stopping criterion to terminate the proposed algorithm is also developed. The lower and upper bounds of probability of failure are calculated based on the final constructed surrogate model. The proposed method is effective because it can provide more accurate reliability results compared with traditional independence assumption reliability methods, and it can be used for structural systems with mixed variables. The proposed method is easy to code and understand. Three numerical examples are investigated to show the applicability of the proposed method.

Calculating the Area within the Orbit of Arrokoth

The area within the orbit of the Kuiper Belt object (KBO) Arrokoth (or 2014MU69) is approximated using the corresponding ellipse. The fact that the Sun lies at a focus of the ellipse is of interest. Attention is made to the known deviations of orbits from their models. It is at least of interest that the ellipse model is still essentially valid. Theoretically, if there were only the Sun and Arrokoth in the Universe, the orbit would be precisely described by the ellipse model.

Hidden-Node Problem in Full-Duplex Enabled CSMA Networks

The in-band full-duplexing is a promising technique to boost wireless network throughput by allowing a node to transmit and receive simultaneously. This paper provides a comprehensive investigation on the hidden-node problem that arises in the full-duplex (FD) enabled carrier-sensing multiple-access (CSMA) networks. In particular, we first provide the fundamental conditions that guarantee successful receptions for all the FD transmission cases, and propose an ellipse interference model and an ellipse carrier-sensing model to capture the interference relations and the carrier-sensing mechanism in FD CSMA networks, respectively. We further establish the hidden-node-free design in FD CSMA networks. Specifically, we show the sufficient conditions on the carrier-sensing power threshold that can eliminate hidden-node collisions. We show that compared with half-duplex CSMA networks, the FD CSMA network needs a much smaller carrier-sensing power threshold to prevent hidden-node collisions, which leads to poor network spatial reuse. This motivates us to further propose a new medium access control (MAC) protocol with Full-duplex Enhanced Carrier-Sensing (FECS) mechanism. The FECS-MAC enables the secondary carrier-sensing before starting the secondary transmission. We show that with the secondary carrier-sensing design, the required carrier-sensing power threshold can be increased while keeping the network hidden-node free. Therefore, the network spatial reuse and throughput can be significantly improved. Simulation results demonstrate that the FECS-MAC can improve the throughput of dense three-node FD networks by more than 30 percent, compared with relay full-duplex (RFD) MAC protocol proposed in [1] .

UTSM: A Trajectory Similarity Measure Considering Uncertainty Based on an Amended Ellipse Model

Measuring the similarity between a pair of trajectories is the basis of many spatiotemporal clustering methods and has wide applications in trajectory pattern mining. However, most measures of trajectory similarity in the literature are based on precise models that ignore the inherent uncertainty in trajectory data recorded by sensors. Traditional computing or mining approaches that assume the preciseness and exactness of trajectories therefore risk underperforming or returning incorrect results. To address the problem, we propose an amended ellipse model which takes both interpolation error and positioning error into account by making use of motion features of trajectory to compute the ellipse’s shape parameters. A specialized similarity measure method considering uncertainty called UTSM based on the model is also proposed. We validate the approach experimentally on both synthetic and real-world data and show that UTSM is not only more robust to noise and outliers but also more tolerant of different sample frequencies and asynchronous sampling of trajectories.

Characteristics of pitting corrosion in an existing reinforced concrete beam exposed to marine environment

Pitting corrosion is a threat to structural durability, causing stress concentration and severe effects on bearing capacity. In this study, two types of corrosion pits were observed in an existing beam exposed to a marine environment for forty years: a wide-shallow pit and narrow-deep pit. Considering the pitting corrosion depth and width as key parameters, an ellipse model was proposed to describe the pit shape. The ratio between the maximum and the average corrosion penetration, called pitting factor, was found to fluctuate between 2 and 4 for the wide-shallow pit and between 4 and 8 for the narrow-deep pit.

Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH4

Using a combination of velocity-map imaging and resonance-enhanced multiphoton ionization detection with crossed molecular beam scattering, the dynamics of rotational energy transfer have been examined for NO in collisions with CH4 at a mean collision energy of 700 cm-1. The images of NO scattered into individual rotational (jNO') and spin-orbit (Ω) levels typically exhibit a single broad maximum that gradually shifts from the forward to the backward scattering direction with increasing rotational excitation (i.e., larger ΔjNO). The rotational rainbow angles calculated with a two-dimensional hard ellipse model show reasonable agreement with the observed angles corresponding to the maxima in the differential cross sections extracted from the images for higher ΔjNO transitions, but there are clear discrepancies for lower ΔjNO (in particular, final rotational levels with jNO' = 7.5 and 8.5). The sharply forward scattered angular distributions for these lower ΔjNO transitions better agree with the predictions of an L-type rainbow model. The more highly rotationally excited NO appears to coincide with low rotational excitation of the co-product CH4, indicating a degree of rotational product-pair anticorrelation in this bimolecular scattering.

The application of Voronoi algorithm in the planning of forest-fire

Voronoi graph method is used for forest-fire relief supplies’ shortest way of planning. Global path planning model has been established initially based on Voronoi and Geography Information System (GIS) method. Ellipse model is used to express forest fire spread region. For simplified computation, the excircle of the ellipse instead is utilized to calculate threat degree, which also makes the planned route has bigger security. In order to enhance flight vehicle’s feasibility, smooth processing carries on above path’s elevation by grade limitation smooth algorithm and curvature limit smooth algorithm. The simulation result shows: this simple plan method might effectively solve the problem of vehicle’s 3D global path planning, simultaneously also lay the foundation for the actual flight in dynamic flight path planning.