Active control effectiveness and synchronization of wall turbulence under localized imposed unsteadiness

Recently, the semi-active control method has attracted significant attention from many researchers and engineers. This method aims to minimize a structure's response by changing the damper capacity according to the state of the structure and the external loads, and various kinds of semi-active control algorithms have been proposed. A lot of them utilize mathematically difficult algorithms that require complicated computer systems. With these methods, we can not evaluate the effectiveness and overall safety of the system under various kinds of loads. One reason is that the behaviors of structures incorporating such complicated control systems can not be evaluated by conventional means such as equivalent viscous damping factor based on hysteresis. Therefore, a semi-active control system is wished in which the control effects can be easily quantified as with passive control systems. This paper describes the result of having proposed the simple quantification approach for the semi-active control effectiveness.

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Active Control of Wall Turbulence with Wall Deformation

JSME International Journal Series B ◽

10.1299/jsmeb.44.195 ◽

2001 ◽

Vol 44 (2) ◽

pp. 195-203 ◽

Cited By ~ 2

Author(s):

Takahide ENDO ◽

Nobuhide KASAGI

Keyword(s):

Active Control ◽

Wall Turbulence ◽

Wall Deformation

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Effect of active control on optimal structures in wall turbulence

Science China Physics Mechanics and Astronomy ◽

10.1007/s11433-013-4995-7 ◽

2013 ◽

Vol 56 (2) ◽

pp. 290-297 ◽

Cited By ~ 8

Author(s):

BingQing Deng ◽

ChunXiao Xu ◽

WeiXi Huang ◽

GuiXiang Cui

Keyword(s):

Active Control ◽

Wall Turbulence ◽

Optimal Structures

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Active Control of Sound Radiation Pressure

Journal of Vibration and Acoustics ◽

10.1115/1.2930118 ◽

1990 ◽

Vol 112 (2) ◽

pp. 237-244 ◽

Cited By ~ 18

Author(s):

L. Meirovitch ◽

S. Thangjitham

Keyword(s):

Active Control ◽

Radiation Pressure ◽

Acoustic Radiation ◽

Excitation Frequency ◽

Design Parameters ◽

Simply Supported ◽

Control Effectiveness ◽

Field Radiation ◽

Rectangular Elastic Plate ◽

Acoustic Radiation Pressure

This paper is concerned with the problem of suppressing the acoustic radiation pressure generated by a structure vibrating in air. The approach is to control the vibration of the modes of the structure most responsible for the radiation pressure. This control is carried out by active means, i. e., by feedback control. As a numerical example, the problem of active control of the far-field radiation pressure generated by the vibration of a simply-supported rectangular elastic plate is considered. The influence on the control effectiveness of various design parameters, such as the number of controlled modes, the choice of controlled modes, the number of actuators and the location of the actuators, is investigated. The conclusion is that, depending on the magnitude of the excitation frequency, satisfactory control can be achieved by using a sufficient number of actuators and by controlling a relatively large number of modes.

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Active control of streak structures in wall turbulence using an actuator array producing inclined wavy disturbances

Journal of Turbulence ◽

10.1088/1468-5248/3/1/015 ◽

2002 ◽

Vol 3 ◽

pp. N15 ◽

Cited By ~ 7

Author(s):

Takehiko Segawa ‡ ◽

Yasuo Kawaguchi ◽

Yoshihiro Kikushima ◽

Hiro Yoshida

Keyword(s):

Active Control ◽

Wall Turbulence

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Adaptive non-inferiority margins under observable non-constancy

Statistical Methods in Medical Research ◽

10.1177/0962280218801134 ◽

2018 ◽

Vol 28 (10-11) ◽

pp. 3318-3332 ◽

Cited By ~ 2

Author(s):

Brett Hanscom ◽

James P Hughes ◽

Brian D Williamson ◽

Deborah Donnell

Keyword(s):

Active Control ◽

Type I Error ◽

Population Characteristics ◽

Controlled Trials ◽

Type I ◽

Control Effectiveness ◽

Control Product ◽

Study Population ◽

Baseline Characteristics ◽

Control Therapy

A central assumption in the design and conduct of non-inferiority trials is that the active-control therapy will have the same degree of effectiveness in the planned non-inferiority trial as in the prior placebo-controlled trials used to define the non-inferiority margin. This is referred to as the ‘constancy’ assumption. If the constancy assumption fails, decisions based on the chosen non-inferiority margin may be incorrect, and the study runs the risk of approving an inferior product or failing to approve a beneficial product. The constancy assumption cannot be validated in a trial without a placebo arm, and it is unlikely ever to be met completely. When there are strong, observable predictors of constancy, such as dosing and adherence to the active-control product, we can specify conditions where the constancy assumption will likely fail. We propose a method for using measurable predictors of active-control effectiveness to specify non-inferiority margins targeted to the planned study population characteristics. We describe a pre-specified method, using baseline characteristics or post-baseline predictors in the active-control arm, to adapt the non-inferiority margin at the end of the study if constancy is violated. Adaptive margins can help adjust for constancy violations that will inevitably occur in real clinical trials, while maintaining pre-specified levels of Type I error and power.

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