Ruppert's Delaunay Triangulation Refinement Scheme for Optimal RSUs Placement in Vehicle to Infrastructure Communication Network

Road Side Units(RSUs)are the essential component of vehicular communication for the objective of improving safety and mobility in the road transportation.RSUs are generally deployed at the roadside and more specifically at the intersections in order to collect traffic information from the vehicles and disseminate alarms and messages in emergency situations to the neighborhood vehicles cooperating with the network.However,the development of a predominant RSUs placement algorithm for ensuring competent communication in VANETs is a challenging issue due to the hindrance of obstacles like water bodies,trees and buildings.In this paper,Ruppert’s Delaunay Triangulation Refinement Scheme(RDTRS)for optimal RSUs placement is proposed for accurately estimating the optimal number of RSUs that has the possibility of enhancing the area of coverage during data communication.This RDTRS is proposed by considering the maximum number of factors such as global coverage,intersection popularity,vehicle density and obstacles present in the map for optimal RSUs placement,which is considered as the core improvement over the existing RSUs optimal placement strategies.It is contributed for deploying requisite RSUs with essential transmission range for maximal coverage in the convex map such that each position of the map could be effectively covered by at least one RSU in the presence of obstacles.The simulation experiments of the proposed RDTRS are conducted with complex road traffic environments.The results of this proposed RDTRS confirmed its predominance in reducing the end-to-end delay by 21.32%,packet loss by 9.38%with improved packet delivery rate of 10.68%,compared to the benchmarked schemes.

COMBINED DELAUNAY TRIANGULATION AND ADAPTIVE FINITE ELEMENT METHOD FOR CRACK GROWTH ANALYSIS

The paper presents the utilization of the adaptive Delaunay triangulation in the finite element modeling of two dimensional crack propagation problems, including detailed description of the proposed procedure which consists of the Delaunay triangulation algorithm and an adaptive remeshing technique. The adaptive remeshing technique generates small elements around crack tips and large elements in the other regions. The resulting stress intensity factors and simulated crack propagation behavior are used to evaluate the effectiveness of the procedure. Three sample problems of a center cracked plate, a single edge cracked plate and a compact tension specimen, are simulated and their results assessed.

三角互证(Triangulation)研究方法在教育学研究中的应用

人种学研究中的三角互证(Triangulation)研究方法也可以应用到教育学的研究中,目的是提高研究结果的可信度和有效性。本文将结合笔者的研究经验,讨论三角互证研究方法三个阶段以及研究手段:观察、使用调查问卷以及访问,从而进一步阐释三角互证如何从三个角度避免单一研究方法所带来的数据局限性。

New deghosting method based on generalized triangulation

A new deghosting method based on the generalized triangulation is presented. First, two intersection points corresponding to the emitter position are obtained by utilizing two azimuth angles and two elevation angles from two jammed 3-D radars （or 2-D passive sensors）. Then, hypothesis testing based deghosting method in the multiple target scenarios is proposed using the two intersection points. In order to analyze the performance of the proposed method, the correct association probability of the true targets and the incorrect association probability of the ghost targets are defined. Finally, the Monte Carlo simulations are given for the proposed method compared with the hinge angle method in the cases of both two and three radars. The simulation results show that the proposed method has better performance than the hinge angle method in three radars case.

DELAUNAY TRIANGULATION METHOD OF CURVED SURFACES BASED ON RIEMANNIAN METRIC

A method for quality mesh generation of parametric curved surfaces isproposed. It is shown that the main difference between the proposed method and previous ones is thatour meshing process is done completely in the parametric domains with the guarantee of meshquality. To obtain this aim, the Delaunay method is extended to anisotropic context of 2D domains,and a Riemannian metric map is introduced to remedy the mapping distortion from object space toparametric domain. Compared with previous algorithms, the approach is much simpler, more robust andspeedy. The algorithm is implemented and examples for several geometries are presented todemonstrate the efficiency and validity of the method.

Introducing tree neighbouring relationship factors in forest pattern spatial analysis:weighted Delaunay triangulation method

It is important to quantify and analyze forest spatial patterns for studying biological characteristics,population interaction and the relationship between the population and environment.In this study,the forest spatial structure unit was generated based on the Delaunay triangulation model(DTM),and the weights were generated using the comprehensive values of the tree diameter at breast height,total height and crown width.The distance between neighbors determined by the DTM was weighted to transform the original coordinates of trees into logical coordinates.Then,a weighted spatial pattern(WSP)was developed.After weighting,the neighboring trees were replaced,the replacement ratio was 38.3%,and there was 57.4%of the central tree.Correlation analysis showed that the uniform angle index of the WSP was significantly correlated with the tree size standard deviation under uniformity(r=0.932)and randomness(r=0.711).The DTM method not only considers the spatial distance between trees,but also considers the non-spatial attributes of trees.By changing the spatial topological relation between trees,this method further improves the spatial structure measurement of forest.

Triangulation of red sprites observed above a mesoscale convective system in North China

The triangulation of red sprites was obtained, based on concurrent observations over a mesoscale convective system(MCS) in North China from two stations separated by about 450 km. In addition, broadband sferics from the sprite-producing lightning were measured at five ground stations, making it possible to locate and identify the individual causative lightning discharges for different elements in this dancing sprite event. The results of our analyses indicate that the sprites were produced above the trailing stratiform region of the MCS, and their parent strokes were located mainly in the peripheral area of the stratiform. The lateral offset between sprites and causative strokes ranges from a few km to more than 50 km. In a particularly bright sprite, with a distinct halo feature and streamers descending down to an altitude of approximately 48 km, the sprite current signal identified in the electric sferic, measured at a range of about 1,110 km, peaked at approximately 1 ms after the return stroke.

A new insertion sequence for incremental Delaunay triangulation

Incremental algorithm is one of the most popular procedures for constructing Delaunay triangulations （DTs）. However, the point insertion sequence has a great impact on the amount of work needed for the construction of DTs. It affects the time for both point location and structure update, and hence the overall computational time of the triangulation algorithm. In this paper, a simple deterministic insertion sequence is proposed based on the breadth-first-search on a Kd-tree with some minor modifications for better performance. Using parent nodes as search-hints, the proposed insertion sequence proves to be faster and more stable than the Hilbert curve order and biased randomized insertion order （BRIO）, especially for non-uniform point distributions over a wide range of benchmark examples.

ADAPTIVE DELAUNAY TRIANGULATION WITH MULTIDIMENSIONAL DISSIPATION SCHEME FOR HIGH-SPEED COMPRESSIBLE FLOW ANALYSIS

Adaptive Delaunay triangulation is combined with the cell-centered upwinding algorithm to analyze inviscid high-speed compressible flow problems. The multidimensional dissipation scheme was developed and included in the upwinding algorithm for unstructured triangular meshes to improve the computed shock wave resolution. The solution accuracy is further improved by coupling an error estimation procedure to a remeshing algorithm that generates small elements in regions with large change of solution gradients, and at the same time, larger elements in other regions. The proposed scheme is further extended to achieve higher-order spatial and temporal solution accuracy. Efficiency of the combined procedure is evaluated by analyzing supersonic shocks and shock propagation behaviors for both the steady and unsteady high-speed compressible flows.

Research on Algorithm of the Point Set in the Plane Based on Delaunay Triangulation

In the paper, an improved algorithm is presented for Delaunay triangulation of the point-set in the plain. Based on the original algorithm, we propose the notion of removing circle. During the process of triangulation, and the circle dynamically moves, the algorithm which is simple and practical, therefore evidently accelerates the process of searching a new point, while generating a new triangle. Then it shows the effect of the algorithm in the finite element mesh.

A Novel Spatial Clustering Algorithm Based on Delaunay Triangulation

Exploratory data analysis is increasingly more necessary as larger spatial data is managed in electro-magnetic media. Spatial clustering is one of the very important spatial data mining techniques which is the discovery of interesting rela-tionships and characteristics that may exist implicitly in spatial databases. So far, a lot of spatial clustering algorithms have been proposed in many applications such as pattern recognition, data analysis, and image processing and so forth. However most of the well-known clustering algorithms have some drawbacks which will be presented later when ap-plied in large spatial databases. To overcome these limitations, in this paper we propose a robust spatial clustering algorithm named NSCABDT (Novel Spatial Clustering Algorithm Based on Delaunay Triangulation). Delaunay dia-gram is used for determining neighborhoods based on the neighborhood notion, spatial association rules and colloca-tions being defined. NSCABDT demonstrates several important advantages over the previous works. Firstly, it even discovers arbitrary shape of cluster distribution. Secondly, in order to execute NSCABDT, we do not need to know any priori nature of distribution. Third, like DBSCAN, Experiments show that NSCABDT does not require so much CPU processing time. Finally it handles efficiently outliers.

基于Monotone Triangulation算法的图像优化技术

矢量图形有着无论放大、缩小,文件容量及画质都不会随之改变的特性,常常被应用于动画、漫画播放和用户界面设计以及导航地图等。其画质高文件小的特性非常适合于存储空间紧张的智能手机、平板电脑等移动设备。但安卓系统在矢量图形绘制方面,使用的是谷歌自己的skia引擎进行绘图,该函数在进行复杂位图向矢量图转换时有时会出现明显缺陷。本文通过研究该矢量图函数库标准OpenVG来改进其自带的AndroidVG图形算法,希望为今后Android系统设计一个更加完善并且符合OpenVG标准的矢量图转换函数库打下基础。

DELAUNAY TRIANGULATION AND IMAGE DENSE MATCHING IN VIEW SYNTHESIS

A new method of view synthesis is proposed based on Delaunay triangulation. The first step of this method is making the Delaunay triangulation of 2 reference images. Secondly, matching the image points using the epipolar geometry constraint. Finally, constructing the third view according to pixel transferring under the trilinear constraint. The method gets rid of the classic time consuming dense matching technique and takes advantage of Delaunay triangulation. So it can not only save the computation time but also enhance the quality of the synthesized view. The significance of this method is that it can be used directly in the fields of video coding, image compressing and virtual reality.

Modified Fully Automatic Triangulation of 3-D Solid

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THE DIMENSION OF SPLINE SPACE S_3~1(△) ON A TYPE OF TRIANGULATION

A harmonic condition that can distinguish whether the dimension of spline space S 1 3( △ ) depends on the geometrical character of triangulation is presented, then on a type of general triangulation the dimension is got.

A Novel Method for Transforming XML Documents to Time Series and Clustering Them Based on Delaunay Triangulation

Nowadays exchanging data in XML format become more popular and have widespread application because of simple maintenance and transferring nature of XML documents. So, accelerating search within such a document ensures search engine’s efficiency. In this paper, we propose a technique for detecting the similarity in the structure of XML documents;in the following, we would cluster this document with Delaunay Triangulation method. The technique is based on the idea of representing the structure of an XML document as a time series in which each occurrence of a tag corresponds to a given impulse. So we could use Discrete Fourier Transform as a simple method to analyze these signals in frequency domain and make similarity matrices through a kind of distance measurement, in order to group them into clusters. We exploited Delaunay Triangulation as a clustering method to cluster the d-dimension points of XML documents. The results show a significant efficiency and accuracy in front of common methods.

Competition Numbers of Several Kinds of Triangulations of a Sphere

It is hard to compute the competition number for a graph in general and characterizing a graph by its competition number has been one of important research problems in the study of competition graphs. Sano pointed out that it would be interesting to compute the competition numbers of some triangulations of a sphere as he got the exact value of the competition numbers of regular polyhedra. In this paper, we study the competition numbers of several kinds of triangulations of a sphere, and get the exact values of the competition numbers of a 24-hedron obtained from a hexahedron by adding a vertex in each face of the hexahedron and joining the vertex added in a face with the four vertices of the face, a class of dodecahedra constructed from a hexahedron by adding a diagonal in each face of the hexahedron, and a triangulation of a sphere with 3n (n≥2) vertices.

Cubic Spline Interpolation on a Class of Triangulations

In this paper, we consider spaces of cubic C^1-spline on a class of triangulations. By using the inductive algorithm, the posed Lagrange interpolation sets are constructed for cubic spline space. It is shown that the class of triangulations considered in this paper are nonsingular for S1/3 spaces. Moreover, the dimensions of those spaces exactly equal to L. L. Schuraaker＇s low bounds of the dimensions. At the end of this paper, we present an approach to construct triangulations from any scattered planar points, which ensures that the obtained triangulations for S1/3 space are nonsingular.

Quality Improvement Algorithm for Tetrahedral Mesh Based on Optimal Delaunay Triangulation

The concept of optimal Delaunay triangulation (ODT) and the corresponding error-based quality metric are first introduced. Then one kind of mesh smoothing algorithm for tetrahedral mesh based on the concept of ODT is examined. With regard to its problem of possible producing illegal elements, this paper proposes a modified smoothing scheme with a constrained optimization model for tetrahedral mesh quality improvement. The constrained optimization model is converted to an unconstrained one and then solved by integrating chaos search and BFGS (Broyden-Fletcher-Goldfarb-Shanno) algorithm efficiently. Quality improvement for tetrahedral mesh is finally achieved by alternately applying the presented smoothing scheme and re-triangulation. Some testing examples are given to demonstrate the effectiveness of the proposed approach.