Poisson–Voronoi Tessellation on a Riemannian Manifold

2020 ◽  
Author(s):  
Pierre Calka ◽  
Aurélie Chapron ◽  
Nathanaël Enriquez
Keyword(s):  
Fixed Point ◽  
Asymptotic Expansion ◽  
Riemannian Manifold ◽  
Poisson Point Process ◽  
Voronoi Tessellation ◽  
Voronoi Cell ◽  
Higher Dimension ◽  
Change Of Variables ◽  
The Mean ◽  
Euclidean Setting

Abstract In this paper, we consider a Riemannian manifold $M$ and the Poisson–Voronoi tessellation generated by the union of a fixed point $x_0$ and a Poisson point process of intensity $\lambda $ on $M$. We obtain a two-term asymptotic expansion, when $\lambda $ goes to infinity, of the mean number of vertices of the Voronoi cell associated with $x_0$. The 1st term of the estimate is equal to the mean number of vertices in the Euclidean setting, while the 2nd term involves the scalar curvature of $M$ at $x_0$. This settles with the proper and rigorous frame the former 2D statement from [ 19] and extends it to higher dimension. The key tool for proving this result is a new change of variables formula of Blaschke–Petkantschin type in the Riemannian setting, which brings out the Ricci curvatures of the manifold.

scholarly journals Pinned Geometric Configurations in Euclidean Space and Riemannian Manifolds

Mathematics ◽  
2021 ◽  
Vol 9 (15) ◽  
pp. 1802
Author(s):  
Alex Iosevich ◽  
Krystal Taylor ◽  
Ignacio Uriarte-Tuero
Keyword(s):  
Fixed Point ◽  
Riemannian Manifold ◽  
Hausdorff Dimension ◽  
Riemannian Manifolds ◽  
Riemannian Metric ◽  
Compact Set ◽  
Geometric Configurations ◽  
Wide Range ◽  
D 12 ◽  
Euclidean Setting

Let M be a compact d-dimensional Riemannian manifold without a boundary. Given a compact set E⊂M, we study the set of distances from the set E to a fixed point x∈E. This set is Δρx(E)={ρ(x,y):y∈E}, where ρ is the Riemannian metric on M. We prove that if the Hausdorff dimension of E is greater than d+12, then there exist many x∈E such that the Lebesgue measure of Δρx(E) is positive. This result was previously established by Peres and Schlag in the Euclidean setting. We give a simple proof of the Peres–Schlag result and generalize it to a wide range of distance type functions. Moreover, we extend our result to the setting of chains studied in our previous work and obtain a pinned estimate in this context.

scholarly journals Asymptotic expansion of low-energy excitations for weakly interacting bosons

2021 ◽  
Vol 9 ◽  
Author(s):  
Lea Boßmann ◽  
Sören Petrat ◽  
Robert Seiringer
Keyword(s):  
Asymptotic Expansion ◽  
Coulomb Potential ◽  
Mean Field ◽  
Low Energy ◽  
Energy Eigenstates ◽  
Bogoliubov Theory ◽  
Weakly Interacting ◽  
Repulsive Coulomb ◽  
The Mean

Abstract We consider a system of N bosons in the mean-field scaling regime for a class of interactions including the repulsive Coulomb potential. We derive an asymptotic expansion of the low-energy eigenstates and the corresponding energies, which provides corrections to Bogoliubov theory to any order in $1/N$ .

Markov paths on the Poisson-Delaunay graph with applications to routeing in mobile networks

2000 ◽  
Vol 32 (01) ◽  
pp. 1-18 ◽  
Author(s):  
F. Baccelli ◽  
K. Tchoumatchenko ◽  
S. Zuyev
Keyword(s):  
Communication Networks ◽  
Mobile Networks ◽  
Path Length ◽  
Euclidean Distance ◽  
Voronoi Tessellation ◽  
Voronoi Cells ◽  
Ergodic Properties ◽  
Potential Applications ◽  
The Mean ◽  
Mobile Communication Networks

Consider the Delaunay graph and the Voronoi tessellation constructed with respect to a Poisson point process. The sequence of nuclei of the Voronoi cells that are crossed by a line defines a path on the Delaunay graph. We show that the evolution of this path is governed by a Markov chain. We study the ergodic properties of the chain and find its stationary distribution. As a corollary, we obtain the ratio of the mean path length to the Euclidean distance between the end points, and hence a bound for the mean asymptotic length of the shortest path. We apply these results to define a family of simple incremental algorithms for constructing short paths on the Delaunay graph and discuss potential applications to routeing in mobile communication networks.

η-PAIRING SUPERCONDUCTIVITY IN THE NEGATIVE-U HUBBARD MODEL: EFFECT OF FLUCTUATIONS AND DISORDER

1994 ◽  
Vol 08 (15) ◽  
pp. 2041-2058
Author(s):  
JÜRGEN STEIN
Keyword(s):  
Phase Diagram ◽  
Asymptotic Expansion ◽  
Hubbard Model ◽  
Strong Coupling ◽  
Mean Field ◽  
Higher Order ◽  
Field Phase ◽  
Effective Pair ◽  
The Mean ◽  
Pair Hopping

We have studied the influence of singular fluctuations around the mean-field solution as well as higher order contributions to the geometry controlled asymptotic expansion of the propagators on η-pairing superconductivity in the strong coupling negative-U Hubbard model in the presence of unpaired electrons. The modifications of the mean-field results due to the introduction of disorder and allowance for finite U are also calculated. Besides the singularities already present in the O(2) nonlinear σ-model we find a filling-depending singular depression of the repulsive effective pair-hopping interaction which strongly alters the mean-field phase diagram and appears to suppress the η-pairing phase near the band edges.

Fracture simulations using edge-based smoothed finite element method for isotropic damage model via Delaunay/Voronoi dual tessellations

2021 ◽  
pp. 105678952110405
Author(s):  
Young Kwang Hwang ◽  
Suyeong Jin ◽  
Jung-Wuk Hong
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Voronoi Tessellation ◽  
Damage Model ◽  
Time Integration ◽  
Voronoi Cell ◽  
Smoothed Finite Element Method ◽  
Isotropic Damage ◽  
Edge Based ◽  
Element Method

In this study, an effective numerical framework for fracture simulations is proposed using the edge-based smoothed finite element method (ES-FEM) and isotropic damage model. The duality between the Delaunay triangulation and Voronoi tessellation is utilized for the mesh construction and the compatible use of the finite element solution with the Voronoi-cell lattice geometry. The mesh irregularity is introduced to avoid calculating the biased crack path by adding random variation in the nodal coordinates, and the ES-FEM elements are defined along the Delaunay edges. With the Voronoi tessellation, each nodal mass is calculated and the fractured surfaces are visualized along the Voronoi edges. The rotational degrees of freedom are implemented for each node by introducing the elemental formulation of the Voronoi-cell lattice model, and the accurate visualizations of the rotational motions in the Voronoi diagram are achieved. An isotropic damage model is newly incorporated into the ES-FEM formulation, and the equivalent elemental length is introduced with an additional geometric factor to simulate the consistent softening behaviors with reducing the mesh sensitivity. The full matrix form of the smoothed strain-displacement matrix is constructed for optimal use in the element-wise computations during explicit time integration, and parallel computing is implemented for the enhancement of the computational efficiency. The simulated results are compared with the theoretical solutions or experimental results, which demonstrates the effectiveness of the proposed methodology in the simulations of the quasi-brittle fractures.

The sectional Poisson Voronoi tessellation is not a Voronoi tessellation

1996 ◽  
Vol 28 (02) ◽  
pp. 356-376 ◽  
Author(s):  
S. N. Chiu ◽  
R. Van De Weygaert ◽  
D. Stoyan
Keyword(s):  
Stochastic Geometry ◽  
Affine Space ◽  
Voronoi Tessellation ◽  
Voronoi Cell ◽  
Negative Answer ◽  
Fixed Plane ◽  
Standing Question

Is the intersection between an arbitrary but fixed plane and the spatial Poisson Voronoi tessellation a planar Voronoi tessellation? In this paper a negative answer is given to this long-standing question in stochastic geometry. The answer remains negative for the intersection between at-dimensional linear affine space and thed-dimensional Poisson Voronoi tesssellation, where 2 ≦t≦d− 1. Moreover, it is shown that each cell on this intersection is almost surely a non-Voronoi cell.

Approximations of large trunk line systems under heavy traffic

1994 ◽  
Vol 26 (04) ◽  
pp. 1063-1094
Author(s):  
Harold J. Kushner
Keyword(s):  
Fixed Point ◽  
Heavy Traffic ◽  
Service Capacity ◽  
Mean Values ◽  
Reflected Diffusion ◽  
Trunk Line ◽  
Overflow Traffic ◽  
The Mean ◽  
The Many ◽  
Fully Connected

The paper deals with large trunk line systems of the type appearing in telephone networks. There are many nodes or input sources, each pair of which is connected by a trunk line containing many individual circuits. Traffic arriving at either end of a trunk line wishes to communicate to the node at the other end. If the direct route is full, a rerouting might be attempted via an alternative route containing several trunks and connecting the same endpoints. The basic questions concern whether to reroute, and if so how to choose the alternative path. If the network is ‘large’ and fully connected, then the overflow traffic which is offered for rerouting to any trunk comes from many other trunks in the network with no one dominating. In this case one expects that some sort of averaging method can be used to approximate the rerouting requests and hence simplify the analysis. Essentially, the overflow traffic that a trunk offers the network for rerouting is in some average sense similar to the overflow traffic offered to that trunk. Indeed, a formalization of this idea involves the widely used (but generally heuristic) ‘fixed point' approximation method. One sets up the fixed point equations for appropriate rerouting strategies and then solves them to obtain an approximation to the system loss. In this paper we work in the heavy traffic regime, where the external offered traffic to any trunk is close to the service capacity of that trunk. It is shown that, as the number of links and circuits within each link go to infinity and for a variety of rerouting strategies, the system can be represented by an averaged limit. This limit is a reflected diffusion of the McKean–Vlasov (propagation of chaos) type, where the driving terms depend on the mean values of the solution of the equation. The averages occur due to the symmetry of the network and the averaging effects of the many interactions. This provides a partial justification for the fixed point method. The concrete dynamical systems flavor of the approach and the representations of the limit processes provide a useful way of visualizing the system and promise to be useful for the development of numerical methods and further analysis.

scholarly journals Insensitivity of the mean field limit of loss systems under SQ(d) routeing

2019 ◽  
Vol 51 (4) ◽  
pp. 1027-1066
Author(s):  
Thirupathaiah Vasantam ◽  
Arpan Mukhopadhyay ◽  
Ravi R. Mazumdar
Keyword(s):  
Fixed Point ◽  
Service Time ◽  
Mean Field ◽  
Service Time Distribution ◽  
Field Limit ◽  
Mean Field Limit ◽  
Mean Field Equations ◽  
The Mean ◽  
Loss Systems ◽  
Exponential Case

AbstractIn this paper, we study a large multi-server loss model under the SQ(d) routeing scheme when the service time distributions are general with finite mean. Previous works have addressed the exponential service time case when the number of servers goes to infinity, giving rise to a mean field model. The fixed point of the limiting mean field equations (MFEs) was seen to be insensitive to the service time distribution in simulations, but no proof was available. While insensitivity is well known for loss systems, the models, even with state-dependent inputs, belong to the class of linear Markov models. In the context of SQ(d) routeing, the resulting model belongs to the class of nonlinear Markov processes (processes whose generator itself depends on the distribution) for which traditional arguments do not directly apply. Showing insensitivity to the general service time distributions has thus remained an open problem. Obtaining the MFEs in this case poses a challenge due to the resulting Markov description of the system being in positive orthant as opposed to a finite chain in the exponential case. In this paper, we first obtain the MFEs and then show that the MFEs have a unique fixed point that coincides with the fixed point in the exponential case, thus establishing insensitivity. The approach is via a measure-valued Markov process representation and the martingale problem to establish the mean field limit.

scholarly journals Submanifolds and the length of the second fundamental tensor

1983 ◽  
Vol 34 (1) ◽  
pp. 1-6
Author(s):  
Thomas Hasanis
Keyword(s):  
Riemannian Manifold ◽  
Constant Curvature ◽  
Positive Constant ◽  
Mean Curvature ◽  
Sufficient Condition ◽  
Fundamental Tensor ◽  
The Mean

AbstractA sufficient condition, for a complete submanifold of a Riemannian manifold of positive constant curvature to be umbilical, is given. The condition will be given by an inequality which is established between the length of the second fundamental tensor and the mean curvature.

scholarly journals Asymptotic properties of random Voronoi cells with arbitrary underlying density

2020 ◽  
Vol 52 (2) ◽  
pp. 655-680
Author(s):  
Isaac Gibbs ◽  
Linan Chen
Keyword(s):  
Fixed Point ◽  
Probability Density Function ◽  
Probability Density ◽  
Density Function ◽  
Voronoi Diagram ◽  
Poisson Point Process ◽  
Asymptotic Properties ◽  
Geometric Properties ◽  
Asymptotic Behaviors ◽  
Voronoi Cells

AbstractWe consider the Voronoi diagram generated by n independent and identically distributed $\mathbb{R}^{d}$ -valued random variables with an arbitrary underlying probability density function f on $\mathbb{R}^{d}$ , and analyze the asymptotic behaviors of certain geometric properties, such as the measure, of the Voronoi cells as n tends to infinity. We adapt the methods used by Devroye et al. (2017) to conduct a study of the asymptotic properties of two types of Voronoi cells: (1) Voronoi cells that have a fixed nucleus; (2) Voronoi cells that contain a fixed point. We show that the geometric properties of both types of cells resemble those in the case when the Voronoi diagram is generated by a homogeneous Poisson point process. Additionally, for the second type of Voronoi cells, we determine the limiting distribution, which is universal in all choices of f, of the re-scaled measure of the cells.

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