scholarly journals Optimal transient growth on a vortex ring and its transition via cascade of ringlets

2017 ◽  
Vol 832 ◽  
pp. 269-286 ◽  
Author(s):  
X. Mao ◽  
F. Hussain
Keyword(s):  
Vortex Ring ◽  
Random Disturbance ◽  
Transient Growth ◽  
Time Intervals ◽  
Main Ring ◽  
Dynamics And Control ◽  
Ring Structures ◽  
Nonlinear Transient ◽  
Short Time ◽  
And Control

Linear and nonlinear transient growths of perturbations on a vortex ring up to Reynolds number ($\equiv$ circulation/viscosity) $Re=27\,000$ are studied. For short time intervals, perturbations around the ring axis undergo the strongest linear transient growth and lead to secondary structures in the form of ringlets, owing to the Orr mechanism and an inviscid vorticity-amplification mechanism: in contrast to the well-reported instabilities and lobe structures along the vortex ring core. These secondary ringlet structures induce a tertiary group of ringlets through similar transient perturbation growth. This cascade of ringlets lead to the breakup of the main ring even before activation of the vortex-core instabilities. Such a cascade scenario is also observed in the development of a vortex ring perturbed by random disturbance in the axis region. These new modes and mechanisms for the generation and breakup of vortex ring structures bring insights into the dynamics and control of vortex ring flows.

scholarly journals An Electromechanical Pendulum Robot Arm in Action: Dynamics and Control

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
A. Notué Kadjie ◽  
P. R. Nwagoum Tuwa ◽  
Paul Woafo
Keyword(s):  
Control Strategies ◽  
Dynamical Behavior ◽  
Mechanical Vibration ◽  
High Amplitude ◽  
Electrical Signal ◽  
Electrical Circuit ◽  
Robot Arm ◽  
Dynamics And Control ◽  
Short Time ◽  
And Control

The authors numerically investigate the dynamics and control of an electromechanical robot arm consisting of a pendulum coupled to an electrical circuit via an electromagnetic mechanism. The analysis of the dynamical behavior of the electromechanical device powered by a sinusoidal power source is carried out when the effects of the loads on the arm are neglected. It is found that the device exhibits period-n T oscillations and high amplitude oscillations when the electric current is at its smallest value. The specific case which considers the effects of the impulsive contact force caused by an external load mass pushed by the arm is also studied. It is found that the amplitude of the impulse force generates several behaviors such as jump of amplitude and distortions of the mechanical vibration and electrical signal. For more efficient functioning of the device, both piezoelectric and adaptive backstepping controls are applied on the system. It is found that the control strategies are able to mitigate the signal distortion and restore the dynamical behavior to its normal state or reduce the effects of perturbations such as a short time variation of one component or when the robot system is subject to noises.

scholarly journals State leakage during fast decay and control of a superconducting transmon qubit

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Aravind Plathanam Babu ◽  
Jani Tuorila ◽  
Tapio Ala-Nissila
Keyword(s):  
Theoretical Modeling ◽  
Relevant Parameter ◽  
Von Neumann ◽  
Single Qubit ◽  
Dynamics And Control ◽  
Qubit Gate ◽  
Short Time ◽  
And Control ◽  
Higher Excited States

AbstractSuperconducting Josephson junction qubits constitute the main current technology for many applications, including scalable quantum computers and thermal devices. Theoretical modeling of such systems is usually done within the two-level approximation. However, accurate theoretical modeling requires taking into account the influence of the higher excited states without limiting the system to the two-level qubit subspace. Here, we study the dynamics and control of a superconducting transmon using the numerically exact stochastic Liouville–von Neumann equation approach. We focus on the role of state leakage from the ideal two-level subspace for bath induced decay and single-qubit gate operations. We find significant short-time state leakage due to the strong coupling to the bath. We quantify the leakage errors in single-qubit gates and demonstrate their suppression with derivative removal adiabatic gates (DRAG) control for a five-level transmon in the presence of decoherence. Our results predict the limits of accuracy of the two-level approximation and possible intrinsic constraints in qubit dynamics and control for an experimentally relevant parameter set.

Proposal of PV Output Estimate Method in Short Time Intervals

2016 ◽  
Vol 136 (12) ◽  
pp. 891-897 ◽  
Author(s):  
Katsuhiro Matsuda ◽  
Kazuhiro Misawa ◽  
Hirotaka Takahashi ◽  
Kenta Furukawa ◽  
Satoshi Uemura
Keyword(s):  
Time Intervals ◽  
Estimate Method ◽  
Short Time

PROJECT ON ELECTRONIC STEERING SYSYTEM

2018 ◽  
Vol 4 (5) ◽  
pp. 7
Author(s):  
Shivam Dwivedi ◽  
Prof. Vikas Gupta
Keyword(s):  
Steering System ◽  
Essential Elements ◽  
Variable Pressure ◽  
Passenger Cars ◽  
Control Techniques ◽  
Steering Mechanism ◽  
Dynamics And Control ◽  
Active Research ◽  
Electronic Steering ◽  
And Control

As the four-wheel steering (4WS) system has great potentials, many researchers' attention was attracted to this technique and active research was made. As a result, passenger cars equipped with 4WS systems were put on the market a few years ago. This report tries to identify the essential elements of the 4WS technology in terms of vehicle dynamics and control techniques. Based on the findings of this investigation, the report gives a mechanism of electronically controlling the steering system depending on the variable pressure applied on it. This enhances the controlling and smoothens the operation of steering mechanism.

EVALUATION OF SHORT TIME INTERVALS IN NORMAL AGING AND LATE-LIFE DEPRESSIONS

2020 ◽  
pp. 54-69
Author(s):  
Elena Yu. Balashova ◽  
◽  
Lika I. Mikeladze ◽  
Elena K. Kozlova ◽  
◽  
...  
Keyword(s):  
Late Life ◽  
Normal Aging ◽  
Time Intervals ◽  
Short Time
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