scholarly journals A Passive Control Method for Single Joint Exoskeleton Based on Hill Model

2016 ◽  
Author(s):  
Han Wu ◽  
Qing Wei ◽  
Jian Wang
Keyword(s):  
Passive Control ◽  
Control Method ◽  
Hill Model

Disorganization of a hole tone feedback loop by an axisymmetric obstacle on a downstream end plate

2014 ◽  
Vol 757 ◽  
pp. 908-942 ◽  
Author(s):  
K. Matsuura ◽  
M. Nakano
Keyword(s):  
Nozzle Exit ◽  
Passive Control ◽  
Control Method ◽  
Three Dimensional ◽  
Acoustic Power ◽  
Shear Layers ◽  
Mean Velocity ◽  
End Plate ◽  
Air Jet ◽  
Practical Engineering

AbstractThis study investigates the suppression of the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole tone, is encountered in many practical engineering situations. The mean velocity of the air jet $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}u_0$ was $6\text {--}12\ \mathrm{m}\ {\mathrm{s}}^{-1}$. The nozzle and the end plate hole both had a diameter of 51 mm, and the impingement length $L_{im}$ between the nozzle and the end plate was 50–90 mm. We propose a novel passive control method of suppressing the tone with an axisymmetric obstacle on the end plate. We find that the effect of the obstacle is well described by the combination ($W/L_{im}$, $h$) where $W$ is the distance from the edge of the end plate hole to the inner wall of the obstacle, and $h$ is the obstacle height. The tone is suppressed when backflows from the obstacle affect the jet shear layers near the nozzle exit. We do a direct sound computation for a typical case where the tone is successfully suppressed. Axisymmetric uniformity observed in the uncontrolled case is broken almost completely in the controlled case. The destruction is maintained by the process in which three-dimensional vortices in the jet shear layers convect downstream, interact with the obstacle and recursively disturb the jet flow from the nozzle exit. While regions near the edge of the end plate hole are responsible for producing the sound in the controlled case as well as in the uncontrolled case, acoustic power in the controlled case is much lower than in the uncontrolled case because of the disorganized state.

scholarly journals A Critical Review of Supersonic Flow Control for High-Speed Applications

2021 ◽  
Vol 11 (15) ◽  
pp. 6899
Author(s):  
Abdul Aabid ◽  
Sher Afghan Khan ◽  
Muneer Baig
Keyword(s):  
Supersonic Flow ◽  
Flow Control ◽  
Active Control ◽  
Critical Review ◽  
High Speed ◽  
Passive Control ◽  
Control Method ◽  
Sudden Expansion ◽  
Control Approach ◽  
Cost Efficient

In high-speed fluid dynamics, base pressure controls find many engineering applications, such as in the automobile and defense industries. Several studies have been reported on flow control with sudden expansion duct. Passive control was found to be more beneficial in the last four decades and is used in devices such as cavities, ribs, aerospikes, etc., but these need additional control mechanics and objects to control the flow. Therefore, in the last two decades, the active control method has been used via a microjet controller at the base region of the suddenly expanded duct of the convergent–divergent (CD) nozzle to control the flow, which was found to be a cost-efficient and energy-saving method. Hence, in this paper, a systemic literature review is conducted to investigate the research gap by reviewing the exhaustive work on the active control of high-speed aerodynamic flows from the nozzle as the major focus. Additionally, a basic idea about the nozzle and its configuration is discussed, and the passive control method for the control of flow, jet and noise are represented in order to investigate the existing contributions in supersonic speed applications. A critical review of the last two decades considering the challenges and limitations in this field is expressed. As a contribution, some major and minor gaps are introduced, and we plot the research trends in this field. As a result, this review can serve as guidance and an opportunity for scholars who want to use an active control approach via microjets for supersonic flow problems.

Secure Communication with Chaos and Electronic Circuit Design Using Passivity-Based Synchronization

2017 ◽  
Vol 27 (04) ◽  
pp. 1850057 ◽  
Author(s):  
Uğur Erkin Kocamaz ◽  
Serdar Çiçek ◽  
Yılmaz Uyaroğlu
Keyword(s):  
Numerical Simulation ◽  
Circuit Design ◽  
Communication System ◽  
Secure Communication ◽  
Passive Control ◽  
Electronic Circuit ◽  
Control Method ◽  
Data Communication ◽  
Matlab Simulink ◽  
Electronic Circuit Design

This work deals with the passive control-based chaos synchronization with circuit design for secure communication. First, the numerical simulation and electronic circuit design of a simple five-term chaotic system are performed. The numerical simulation and electronic circuit design outputs have confirmed each other. Then, the passive control method is applied for synchronizing two identical five-term chaotic systems using only one state control signal. After the synchronization study, design and analysis for secure communication by chaotic masking method are conducted in Matlab–Simulink platform. Finally, an electronic circuit design is performed for the designed communication system. In the designed communication system with Matlab–Simulink platform and electronic circuit design, information signal which is sent from the transmitter unit is successfully retrieved at the receiver unit. As a result, the electronic circuit design has shown that a single state passivity-based synchronization signal can be effectively used for secure data communication applications for the real environment.

Passive control of deep cavity shear layer flow at subsonic speed

2017 ◽  
Vol 95 (10) ◽  
pp. 894-899
Author(s):  
Mouhammad El Hassan ◽  
Laurent Keirsbulck
Keyword(s):  
Shear Layer ◽  
Passive Control ◽  
Control Method ◽  
Leading Edge ◽  
Layer Growth ◽  
Cavity Resonance ◽  
Passive Flow Control ◽  
Acoustic Coupling ◽  
Deep Cavity ◽  
Layer Flow

Passive control of the flow over a deep cavity at low subsonic velocity is considered in the present paper. The cavity length-to-depth aspect ratio is L/H = 0.2. particle image velocimetry (PIV) measurements characterized the flow over the cavity and show the influence of the control method on the cavity shear layer development. It is found that both the “cylinder” and the “shaped cylinder”, placed upstream from the cavity leading edge, result in the suppression of the aero-acoustic coupling and highly reduce the cavity noise. It should be noted that the vortical structures impinge at almost the same location near the cavity downstream corner with and without passive control. The present study allows to identify an innovative passive flow control method of cavity resonance. Indeed, the use of a “shaped cylinder” presents similar suppression of the cavity resonance as with the “cylinder” but with less impact on the cavity flow. The “shaped cylinder” results in a smaller shear layer growth than the cylinder. Velocity deficiency and turbulence levels are less pronounced using the “shaped cylinder”. The “cylinder” tends to diffuse the vorticity in the cavity shear layer and thus the location of the maximum vorticity is more affected as compared to the “shaped cylinder” control. The fact that the “shaped cylinder” is capable of suppressing the cavity resonance, despite the vortex shedding and the high frequency forcing being suppressed, is of high interest from fundamental and applied points of view.

Study on the Stability of Non-Structural Element Using Active Tuned Mass Damper

2020 ◽  
Vol 17 (7) ◽  
pp. 3224-3230
Author(s):  
Hong-Won Kim ◽  
Dong-Gi Kwag
Keyword(s):  
High Frequency ◽  
Seismic Waves ◽  
Passive Control ◽  
Control Method ◽  
Amplitude Ratio ◽  
Vibration Reduction ◽  
Tuned Mass Damper ◽  
Structural Element ◽  
High Frequency Region ◽  
Mass Damper

Currently, the frequency of earthquakes is increasing in Korea, but due to the lack of appropriate seismic equipment, significant damage is expected. In order to solve this problem, active tuned mass damper will be developed to reduce earthquake damage in response to seismic waves, which are combined from low frequency to high frequency. In this paper, various control methods are introduced to reduce the amplitude ratio occurring at the 1st and 2nd natural frequencies for 3 DOF nonstructural elements. Through mathematical modeling, we confirm how each control method is applied and present the problems of the existing passive tuned mass damper and suggest the active tuned mass damper. To induce an active copper reducer, the response according to the control method can be predicted with a focus on the energy change rate. The active controller receives feedback from the relative displacement and relative velocity of the structure and uses it as a variable to set the control method. The passive control method and the active control method are compared through the simulation, and excellent control performance can be confirmed in the high frequency region as well as the second natural frequency. Vibration reduction performance was confirmed by each control method and the most ideal control method was selected. The optimum vibration reduction performance can be confirmed by using the signal function to always generate 180° of phase difference with respect to the speed of the structure. Not only earthquake but also mechanical vibration, wind load, etc., it can be used in all fields where damage is caused by excitation force inherent in various complex frequencies.

Design and Simulation of Passive Controller for Guided Rockets

2012 ◽  
Vol 236-237 ◽  
pp. 230-235
Author(s):  
Wei Wei Bian ◽  
Liang Ming Wang ◽  
Yang Zhong
Keyword(s):  
Basic Principle ◽  
Passive Control ◽  
Control Method ◽  
Vertical Wind ◽  
Motion Equations ◽  
Control Scheme ◽  
Simulation Results ◽  
Effective Conditions

In order to increase the density of guided rockets, a passive control method was proposed to reduce the trajectory dispersion caused by initial disturbances, thrust misalignment, vertical wind, etc. at the end of boost phase. The basic principle of passive control method was introduced briefly, and then the disturbance motion equations for the rocket projectile were established. The effective conditions to implement passive control on guided rockets were put forward. A technical scheme of installing elastic sabots on rocket projectile was proposed to realize passive control and a simulation was conducted. The simulation results indicate that the passive control scheme can effectively decrease the velocity direction deviation caused by various disturbances factors at the end of boost phase.

scholarly journals A New Chaotic System with Line of Equilibria: Dynamics, Passive Control and Circuit Design

2019 ◽  
Vol 9 (4) ◽  
pp. 2336 ◽  
Author(s):  
Aceng Sambas ◽  
Mustafa Mamat ◽  
Ayman Ali Arafa ◽  
Gamal M Mahmoud ◽  
Mohamad Afendee Mohamed ◽  
...  
Keyword(s):  
Circuit Design ◽  
Chaotic System ◽  
Passive Control ◽  
Electronic Circuit ◽  
Control Method ◽  
Phase Portraits ◽  
New Chaotic System ◽  
Quadratic Nonlinearities ◽  
Line Of Equilibria ◽  
Line Equilibrium

<p>A new chaotic system with line equilibrium is introduced in this paper. This system consists of five terms with two transcendental nonlinearities and two quadratic nonlinearities. Various tools of dynamical system such as phase portraits, Lyapunov exponents, Kaplan-Yorke dimension, bifurcation diagram and Poincarè map are used. It is interesting that this system has a line of fixed points and can display chaotic attractors. Next, this paper discusses control using passive control method. One example is given to insure the theoretical analysis. Finally, for the  new chaotic system, An electronic circuit for realizing the chaotic system has been implemented. The numerical simulation by using MATLAB 2010 and implementation of circuit simulations by using MultiSIM 10.0 have been performed in this study.</p>

scholarly journals Research and Analysis of Damping Control Technology in Civil Engineering Construction Process

2014 ◽  
Vol 8 (1) ◽  
pp. 406-406
Author(s):  
Yonggang Bao ◽  
Qingwei Meng ◽  
Ki Bae Seo
Keyword(s):  
Active Control ◽  
Passive Control ◽  
Civil Engineering ◽  
Control Method ◽  
Rapid Development ◽  
Rational Approach ◽  
Engineering Structures ◽  
Engineering Construction ◽  
Engineering Structure ◽  
Civil Engineering Structure

With the rapid development of society and the economy, people's life and property safety importance is also more and more high. Especially the occurrence of the Wenchuan earthquake, people on whether the application of civil engineering construction damping scientific and rational approach was questioned. How to ensure the quality of civil engineering construction, to avoid in the event of earthquakes and other natural disasters, the emergence floor crash event, is an issue for all engineering designers and builders focus on. Because of the relationship with all life safety, so how to use rational scientific method damping to the construction of civil engineering structures is very important and necessary. This study from the passive control, active control, semi-active control and hybrid control methods start with four damping research and analysis, combining their research status. The Benchmark problem of structure control has carried on the simple introduction. Focusing on civil engineering structure vibration control method of systematic review, so as to the future of civil engineering structure suspension construction provides the certain reference function

scholarly journals Motion Control of Pentapod Offshore Wind Turbines under Earthquakes by Tuned Mass Damper

2019 ◽  
Vol 7 (7) ◽  
pp. 224 ◽  
Author(s):  
Wenhua Wang ◽  
Xin Li ◽  
Zuxing Pan ◽  
Zhixin Zhao
Keyword(s):  
Seismic Waves ◽  
Passive Control ◽  
Control Method ◽  
Tuned Mass Damper ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Integrated Analysis ◽  
Analysis Model ◽  
Mass Damper ◽  
Structural Responses

The dynamic characteristics of a bottom-fixed offshore wind turbine (OWT) under earthquakes are analyzed by developing an integrated analysis model of the OWT. Further, the influence of the interactions between the rotor and support system on the structural responses of the OWT subjected to an earthquake is discussed. Moreover, a passive control method using a tuned mass damper (TMD) is applied to the OWT to control the responses under earthquakes. The effects of the mass ratio, location and tuned frequency of the TMD on controlling structural responses of the OWT under different recorded seismic waves are studied.

Numerical investigation for flow over a square rod through a passive control method at various Reynolds numbers

2020 ◽  
Vol 98 (5) ◽  
pp. 425-432
Author(s):  
A. Ahmed ◽  
R. Manzoor ◽  
S.U. Islam ◽  
H. Rahman
Keyword(s):  
Flow Regime ◽  
Passive Control ◽  
Control Method ◽  
Sudden Change ◽  
Flow Characteristics ◽  
Flow Regimes ◽  
Reynolds Numbers ◽  
Spacing Ratio ◽  
Boltzmann Method ◽  
Control Rods

This work presents a numerical simulation performed to study the effect of Reynolds number (Re = 80–200) on fluid flow over a square rod attached to two small controlling rods using the Lattice Boltzmann method. For this reason, the spacing ratio between the control rods and main rod varies systematically from g = 0.5–5. Flow has been subdivided into three flow regimes based on spacing ratios. The first flow regime is considered at a small gap (g = 0.5, 1, and 1.5), the second flow regime is obtained at a moderate gap (g = 2, 2.5, and 3), and the third flow regime is considered a at large gap (g = 4–5). Five different types of flow modes were noticed in the given flow regimes. The values Re = 200 and g = 5 were found to be critical due to a sudden change in flow characteristics. The maximum value of Cdmean is 0.869 and the largest percent reduction (65.15%) in the mean drag coefficient was found at Re = 200 and g = 2.

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