scholarly journals On the dynamical model for COVID-19 with vaccination and time-delay effects: A model analysis supported by Yangzhou epidemic in 2021

2021 ◽  
pp. 107783
Author(s):  
Liyan Wang ◽  
Qiang Zhang ◽  
Jijun Liu
Keyword(s):  
Time Delay ◽  
Model Analysis ◽  
Dynamical Model ◽  
Delay Effects

Time Delay Effects on Compactability of Soil-Cement Materials during Proctor Testing

2021 ◽  
pp. 036119812199870
Author(s):  
W. Griffin Sullivan ◽  
Isaac L. Howard
Keyword(s):  
Time Delay ◽  
Vital Role ◽  
Test Method ◽  
Dry Density ◽  
Soil Cement ◽  
Delay Effects ◽  
Proctor Test ◽  
Negative Effect ◽  
Departments Of Transportation ◽  
Cement Mixtures

The Proctor test method, as specified in AASHTO T134 and ASTM D558, continues to play a vital role in design and construction quality control for soil-cement materials. However, neither test method establishes a methodology or standardized protocols to characterize the effects of time delay between cement addition and compaction, also known as compaction delay. Compaction delay has been well documented to have a notably negative effect on compactability, compressive strength, and overall performance of soil-cement materials, but specification tools to address this behavior are not prevalent. This paper aims to demonstrate the extent of compaction delay effects on several soil-cement mixtures used in Mississippi and to present recommended new test method protocols for AASHTO T134 to characterize compaction delay effects. Data presented showed that not all soil-cement mixtures are sensitive to compaction delay, but some mixtures can be very sensitive and lead to a meaningful decrease in specimen dry density. Recommended test method protocols were presented for AASHTO T134 and commentary was presented to provide state Departments of Transportation and other specifying agencies a few examples of how the new compaction delay protocols could be implemented.

Time Delay Effects on Dynamic Patterns in a Coupled Neural Model

2000 ◽  
pp. 268-275
Author(s):  
Seon Hee Park ◽  
Seunghwan Kim ◽  
Hyeon-Bong Pyo ◽  
Sooyeul Lee ◽  
Sang-Kyung Lee
Keyword(s):  
Time Delay ◽  
Neural Model ◽  
Delay Effects ◽  
Dynamic Patterns

Optimally designed Lyapunov–Krasovskii terminal costs for robust stable–feasible model predictive control of uncertain time-delay nonlinear dynamical systems

2020 ◽  
pp. 095965182095219
Author(s):  
S Yaqubi ◽  
MR Homaeinezhad
Keyword(s):  
Time Delay ◽  
Dynamical Systems ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Robust Stability ◽  
Control Algorithm ◽  
Nonlinear Dynamical Systems ◽  
Prediction Horizon ◽  
Delay Effects ◽  
Uncertain Time

This article details a new Model Predictive Control algorithm ensuring robust stability and control feasibility for uncertain nonlinear multi-input multi-output dynamical systems considering uncertain time-delay effects. The proposed control algorithm is based on construction of a Lyapunov–Krasovskii functional as terminal cost. Incorporation of this terminal cost into the Model Predictive Control optimization problem and calculation of the associated admissible set result in robust feasibility and robust stability of closed-loop system in presence of uncertain time-delay effects and bounded disturbance signals. The Lyapunov–Krasovskii functional term is constructed with respect to predicted sliding functions over the prediction horizon and considers the effects of dynamical variations over the prediction horizon in generation of control inputs. As dynamical variations are investigated in a sample-to-sample basis, feasible sliding regions are updated at each sample as well. Finally, based on expression of sliding functions as a combination of dynamical variations and input-based terms, required control inputs are calculated in the admissible bound by the optimization algorithm. Construction of control scheme on this basis permits straightforward calculation of robust stability and feasibility conditions for a general class of uncertain nonlinear system in finite prediction horizon whereas in the previous works, often-restrictive conditions were considered for the investigated dynamical systems. Numerical illustrations indicate precision and efficiency of control algorithm and improved stability and convergence rate for multivariable nonlinear dynamical systems considering uncertain time-delay effects. Finally, hardware-in-the-loop implementation indicates applicability of the proposed scheme in real-time control applications particularly in case appropriate compromises between optimality and calculation speed are considered.

Time-Delay Effects on Linear/Nonlinear Feedback Control of Simple Aeroelastic Systems

2005 ◽  
Vol 28 (1) ◽  
pp. 53-62 ◽  
Author(s):  
Piergiovanni Marzocca ◽  
Liviu Librescu ◽  
Walter A. Silva
Keyword(s):  
Time Delay ◽  
Feedback Control ◽  
Nonlinear Feedback Control ◽  
Nonlinear Feedback ◽  
Delay Effects

On Time-Delay Effects on Period-1 Motions in a Periodically Forced, Time-Delayed, Duffing Oscillator

2016 ◽  
Author(s):  
Albert C. J. Luo ◽  
Siyuan Xing
Keyword(s):  
Time Delay ◽  
Analytical Solutions ◽  
Analytical Method ◽  
Duffing Oscillator ◽  
Delay Systems ◽  
Harmonic Amplitude ◽  
Time Delay Systems ◽  
Periodic Motions ◽  
Delay Effects ◽  
The Stability

In recent decades, nonlinear time-delay systems were often applied in controlling nonlinear systems, and the stability of such time-delay systems was very actively discussed. Recently, one was very interested in periodic motions in nonlinear time-delay systems. Especially, the semi-analytical solutions of periodic motions in time-delay systems are of great interest. From the semi-analytical solutions, the nonlinearity and complexity of periodic motions in the time-delay systems can be discussed. In this paper, time-delay effects on periodic motions of a periodically forced, damped, hardening, Duffing oscillator are analytically discussed through a semi-analytical method. The semi-analytical method is based on discretization of the differential equation of such a Duffing oscillator to obtain the corresponding implicit discrete mappings. Through such implicit mappings and mapping structures of periodic motions, period-1 motions varying with time-delay are discussed, and the corresponding stability and bifurcation analysis of periodic motions are carried out through eigenvalue analysis. Numerical results of periodic motions are illustrated to verify analytical predictions. The corresponding harmonic amplitude spectrums and harmonic phases are presented for a better understanding of periodic motions in such a nonlinear oscillator.

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