scholarly journals Improved Discrete-Time Boundary Condition for the Thin-Wire FDTD Analysis of Lossy Insulated Cylindrical Antennas Located in Lossy Media

2021 ◽  
Vol 21 (1) ◽  
pp. 60-63
Author(s):  
Seung-Yeup Hyun
Keyword(s):  
Boundary Condition ◽  
Discrete Time ◽  
Field Approximation ◽  
Uniform Field ◽  
Thin Wire ◽  
Time Step ◽  
Monopole Antennas ◽  
Lossy Media ◽  
Cylindrical Antennas ◽  
Time Boundary

For the thin-wire (TW) finite-difference time-domain (FDTD) analysis of lossy insulated antennas surrounded by lossy media, an improved discrete-time boundary condition (DTBC) at the interface is proposed here. In previous TW-FDTD techniques, the DTBC formulations on the material discontinuity between the lossy insulation and lossy surrounding media were derived from the dielectric constitutive relation under the uniform field approximation (UFA) over each time step. In this paper, to achieve higher accuracy, an improved DTBC is formulated from Maxwell’s equations under the linear field approximation (LFA) and subsequently corrected in the TW-FDTD update equation. By comparing the input impedances of Teflon-insulated cylindrical monopole antennas located in wet soils, we show that the proposed approach provides higher accuracy than previous techniques.

scholarly journals The Robust Consensus of a Noisy Deffuant-Weisbuch Model

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Jiangbo Zhang ◽  
Yiyi Zhao
Keyword(s):  
Discrete Time ◽  
Model Parameters ◽  
Positive Probability ◽  
Noise Strength ◽  
Opinion Formation ◽  
Time Step ◽  
Absolute Value ◽  
The Difference ◽  
Robust Consensus

We construct a new opinion formation of the Deffuant-Weisbuch model with the interference of the outer noise, where there are finite n agents and the evolution is discrete-time. The opinion interaction occurs by one randomly chosen pair at each time step. The difference to the original Deffuant-Weisbuch model is that communications of any selected pairs will be affected by noises. The aim of this paper is to study the robust consensus of this noisy Deffuant-Weisbuch model. We first define the noise strength as the maximum noise absolute value. We will then show that when the noise strength is less than a certain threshold, this noisy model will achieve T-robust consensus when t is sufficiently large; next we prove that the noisy model achieves robust consensus with a positive probability; finally, we demonstrate these results and provide numerical relations among the noise strength and some model parameters.

H 2-H∞ Control of Discrete Time Nonlinear Systems Using the SDRE Approach

2011 ◽  
Author(s):  
Xin Wang ◽  
Edwin E. Yaz ◽  
Susan C. Schneider ◽  
Yvonne I. Yaz
Keyword(s):  
Riccati Equation ◽  
Discrete Time ◽  
Steady State Solution ◽  
State Feedback Control ◽  
Disturbance Attenuation ◽  
Performance Criteria ◽  
Linear Matrix ◽  
Time Step ◽  
Control Approach ◽  
The Difference

A novel H2–H∞ State Dependent Riccati Equation control approach is presented for providing a generalized control framework to discrete time nonlinear system. By solving a generalized Riccati Equation at each time step, the nonlinear state feedback control solution is found to satisfy mixed performance criteria guaranteeing quadratic optimality with inherent stability property in combination with H∞ type of disturbance attenuation. Two numerical techniques to compute the solution of the resulting Riccati equation are presented: The first one is based on finding the steady state solution of the difference equation at every step and the second one is based on finding the minimum solution of a linear matrix inequality. The effectiveness of the proposed techniques is demonstrated by simulations involving the control of an inverted pendulum on a cart, a benchmark mechanical system.

Discrete Time Finite Element Transfer Matrix Method Development for Modeling and Decentralized Control

2015 ◽  
Author(s):  
Nick Cramer ◽  
Sean Swei ◽  
Kenny Cheung ◽  
M. Teodorescu
Keyword(s):  
Finite Element ◽  
Transfer Matrix ◽  
Discrete Time ◽  
Flight Control ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Structural Control ◽  
Method Development ◽  
Time Step ◽  
Element Transfer

The current emphasis on increasing aeronautical efficiency is leading the way to a new class of lighter more flexible airplane materials and structures, which unfortunately can result in aeroelastic instabilities. To effectively control the wings deformation and shape, appropriate modeling is necessary. Wings are often modeled as cantilever beams using finite element analysis. The drawback of this approach is that large aeroelastic models cannot be used for embedded controllers. Therefore, to effectively control wings shape, a simple, stable and fast equivalent predictive model that can capture the physical problem and could be used for in-flight control is required. The current paper proposes a Discrete Time Finite Element Transfer Matrix (DT-FETMM) model beam deformation and use it to design a regulator. The advantage of the proposed approach over existing methods is that the proposed controller could be designed to suppress a larger number of vibration modes within the fidelity of the selected time step. We will extend the discrete time transfer matrix method to finite element models and present the decentralized models and controllers for structural control.

scholarly journals On explicit form of the stationary distributions for a class of bounded Markov chains

2016 ◽  
Vol 53 (1) ◽  
pp. 231-243 ◽  
Author(s):  
S. McKinlay ◽  
K. Borovkov
Keyword(s):  
Markov Chains ◽  
Closed Form ◽  
State Space ◽  
Explicit Form ◽  
Discrete Time ◽  
Unit Interval ◽  
Time Step ◽  
Stationary Distributions ◽  
End Point ◽  
Current Location

AbstractWe consider a class of discrete-time Markov chains with state space [0, 1] and the following dynamics. At each time step, first the direction of the next transition is chosen at random with probability depending on the current location. Then the length of the jump is chosen independently as a random proportion of the distance to the respective end point of the unit interval, the distributions of the proportions being fixed for each of the two directions. Chains of that kind were the subjects of a number of studies and are of interest for some applications. Under simple broad conditions, we establish the ergodicity of such Markov chains and then derive closed-form expressions for the stationary densities of the chains when the proportions are beta distributed with the first parameter equal to 1. Examples demonstrating the range of stationary distributions for processes described by this model are given, and an application to a robot coverage algorithm is discussed.

A Note on the Uniform Field Approximation when Guard Rings Are Used

1970 ◽  
Vol 38 (12) ◽  
pp. 1452-1454 ◽  
Author(s):  
Kazutoshi Asano ◽  
Arnold W. Dipert ◽  
Charles D. Hendricks
Keyword(s):  
Field Approximation ◽  
Uniform Field

scholarly journals The dynamic competition hypothesis

2021 ◽  
Author(s):  
Rehan Taj Malik
Keyword(s):  
Social Network ◽  
Discrete Time ◽  
Dynamic Competition ◽  
Time Step ◽  
Big Brother ◽  
Social Game ◽  
The Social ◽  
Competition Hypothesis ◽  
Negative Relationships ◽  
Over Time

We study competitive and negative interactions in real world social network in which nodes represent agents and edges appear over discrete time step. We consider directed social network of competing agents that evolve dynamically over time, where directed edges represent some kind of negative relationships between the agents in the social network. We present a novel hypothesis to identify the alliances and leaders within the the dynamic competition networks. We verify our hypothesis by using historical voting data of the social game shows Survivor and Big Brother.

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