arXiv subjects

Yilun Shang

Publications and source records attributed to Yilun Shang.

26 records · Page 2Linked to original sources

arXiv2009

Synchronization in Networks of Coupled Harmonic Oscillators with Stochastic Perturbation and Time Delays

In this paper, we investigate synchronization of coupled second-order linear harmonic oscillators with random noises and time delays. The interaction topology is modeled by a weighted directed graph and the weights are perturbed by white noise. On the basis of stability theory of stochastic differential delay equations, algebraic graph theory and matrix theory, we show that the coupled harmonic oscillators can be synchronized almost surely with perturbation and time delays. Numerical examples are presented to illustrate our theoretical results.

physics.data-an↗

arXiv2009

Leader-following Consensus Problems with a Time-varying Leader under Measurement Noises

In this paper, we consider a leader-following consensus problem for networks of continuous-time integrator agents with a time-varying leader under measurement noises. We propose a neighbor-based state-estimation protocol for every agent to track the leader, and time-varying consensus gains are introduced to attenuate the noises. By combining the tools of stochastic analysis and algebraic graph theory, we study mean square convergence of this multi-agent system under directed fixed as well as switching interconnection topologies. Sufficient conditions are given for mean square consensus in both cases. Finally, a numerical example is given to illustrate our theoretical results.

cs.MA↗

arXiv2009

The Distant-l Chromatic Number of Random Geometric Graphs

A random geometric graph $G_n$ is given by picking $n$ vertices in $\mathbb{R}^d$ independently under a common bounded probability distribution, with two vertices adjacent if and only if their $l^p$-distance is at most $r_n$. We investigate the distant-$l$ chromatic number $χ_l(G_n)$ of $G_n$ for $l\ge1$. Complete picture of the ratios of $χ_l(G_n)$ to the chromatic number $χ(G_n)$ are given in the sense of almost sure convergence.

math.CO↗

arXiv2009

Emergence in Random Noisy Environments

We investigate the emergent behavior of four types of generic dynamical systems under random environmental perturbations. Sufficient conditions for nearly-emergence in various scenarios are presented. Recent fundamental works of F. Cucker and S. Smale on the construction and analysis of flocking models directly inspired our present work.

math.DS↗

arXiv2009

On the Degree Sequence of Random Geometric Digraphs

A random geometric digraph $G_n$ is constructed by taking $\{X_1,X_2,... X_n\}$ in $\mathbb{R}^2$ independently at random with a common bounded density function. Each vertex $X_i$ is assigned at random a sector $S_i$ of central angle $α$ with inclination $Y_i$, in a circle of radius $r$ (with vertex $X_i$ as the origin). An arc is present from vertex $X_i$ to $X_j$, if $X_j$ falls in $S_i$. Suppose $k$ is fixed and $\{k_n\}$ is a sequence with $1\ll k_n\ll n^{1/2}$, as $n\to\infty$. We prove central limit theorems for $k-$ and $k_n-$nearest neighbor distance of out- and in-degrees in $G_n$. We also show that the degree distribution of this model, which varies with the probability distribution of the underlying point processes, can be either homogeneous or inhomogeneous. Our work should provide valuable insights for alternative mechanisms wrapped in real-world complex networks.

math.CO↗

arXiv2009

Multi-agent Coordination in Directed Moving Neighborhood Random Networks

In this paper, we consider the consensus problem of dynamical multiple agents that communicate via a directed moving neighborhood random network. Each agent performs random walk on a weighted directed network. Agents interact with each other through random unidirectional information flow when they coincide in the underlying network at a given instant. For such a framework, we present sufficient conditions for almost sure asymptotic consensus. Some existed consensus schemes are shown to be reduced versions of the current model.

cs.MA↗

arXiv2009

Finite-time Consensus for Nonlinear Multi-agent Systems with Fixed Topologies

In this paper, we study finite-time state consensus problems for continuous nonlinear multi-agent systems. Building on the theory of finite-time Lyapunov stability, we propose sufficient criteria which guarantee the system to reach a consensus in finite time, provided that the underlying directed network contains a spanning tree. Novel finite-time consensus protocols are introduced as examples for applying the criteria. Simulations are also presented to illustrate our theoretical results.

cs.IT↗

arXiv2009

Laws of Large Numbers of Subgraphs in Directed Random Geometric Networks

Given independent random points $\mathcal{X}_n=\{X_1,...,X_n\}$ in $\mathbb{R}^2$, drawn according to some probability density function $f$ on $\mathbb{R}^2$, and a cutoff $r_n>0$ we construct a random geometric digraph $G(\mathcal{X}_n,\mathcal{Y}_n,r_n)$ with vertex set $\mathcal{X}_n$. Each vertex $X_i$ is assigned uniformly at random a sector $S_i$, of central angle $α$ with inclination $Y_i$, in a circle of radius $r_n$ (with vertex $X_i$ as the origin). An arc is present from $X_i$ to $X_j$, if $X_j$ falls in $S_i$. We also introduce another random geometric digraph $G(\mathcal{X}_n,\mathcal{R}_n)$ with vertex set $\mathcal{X}_n=\{X_1,...,X_n\}$ in $\mathbb{R}^d$, $d\ge1$ and an arc present from $X_i$ to $X_j$ if $||X_i-X_j||<R_{n,i}$. Here $\{R_{n,i}\}_{i\ge1}$ are i.i.d. random variables and we may take an arbitrary norm $||\cdot||$. In this paper we investigate two kinds of small subgraphs--induced and isolated--in the above two directed networks, which contribute to understanding the local topology of many spatial networks, such as wireless communication networks. We give some strong laws of large numbers of subgraph counts thus extending those results of Penrose [Random Geometric Graphs, Oxford University Press, 2003].

math.CO↗