scholarly journals Optimal damping concept: features and applications

2021 ◽  
Vol 1864 (1) ◽  
pp. 012033
Author(s):  
E. I. Veremey
Keyword(s):  
Optimal Damping

scholarly journals Damping Studies on PMLG-Based Wave Energy Converter under Oceanic Wave Climates

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 920
Author(s):  
Yue Hong ◽  
Irina Temiz ◽  
Jianfei Pan ◽  
Mikael Eriksson ◽  
Cecilia Boström
Keyword(s):  
Wave Energy ◽  
Energy Production ◽  
Full Range ◽  
Electrical Power ◽  
Damping Coefficient ◽  
Irregular Wave ◽  
Ocean Wave Energy ◽  
Optimal Damping ◽  
The Impact

Wave energy converters (WECs), which are designed to harvest ocean wave energy, have recently been improved by the installation of numerous conversion mechanisms; however, it is still difficult to find an appropriate method that can compromise between strong environmental impact and robust performance by transforming irregular wave energy into stable electrical power. To solve this problem, an investigation into the impact of varied wave conditions on the dynamics of WECs and to determine an optimal factor for WECs to comply with long-term impacts was performed. In this work, we researched the performance of WECs influenced by wave climates. We used a permanent magnet linear generator (PMLG)-based WEC that was invented at Uppsala University. The damping effect was first studied with a PMLG-type WEC. Then, a group of sea states was selected to investigate their impact on the power production of the WEC. Two research sites were chosen to investigate the WEC’s annual energy production as well as a study on the optimal damping coefficient impact. In addition, we compared the WEC’s energy production between optimal damping and constant damping under a full range of sea states at both sites. Our results show that there is an optimal damping coefficient that can achieve the WEC’s maximum power output. For the chosen research sites, only a few optimal damping coefficients were able to contribute over 90% of the WEC’s annual energy production. In light of the comparison between optimal and constant damping, we conclude that, for specific regions, constant damping might be a better choice for WECs to optimize long-term energy production.

scholarly journals Inertial mass damper for vibration control of cable with sag

2018 ◽  
Vol 39 (3) ◽  
pp. 749-760 ◽  
Author(s):  
Zhi-Hao Wang ◽  
Hui Gao ◽  
Bu-qiao Fan ◽  
Zheng-Qing Chen
Keyword(s):  
Inertial Mass ◽  
Damping Coefficient ◽  
Stay Cables ◽  
Modal Damping ◽  
Optimal Damping ◽  
Mass Damper ◽  
Negative Effect ◽  
Supplemental Damping ◽  
Antisymmetric Vibrations ◽  
General Dynamic

It has been theoretically predicted that superior supplemental damping can be generated for a taut cable with an inertial mass damper. This paper extends previous studies to investigate the effect of the cable sag on the efficiency of an inertial mass damper. The general dynamic characteristics of an inclined sag cable with an inertial mass damper installed close to the cable end are theoretically investigated. The parametric analysis of the inertial mass and the damping coefficient of the inertial mass damper are conducted to evaluate the control performance of the cable with different sags. The results show that the inertial mass damper can alleviate the negative effect induced by the cable sag, and the cable sag can even increase modal damping ratios provided by the inertial mass damper. Sags of stay cables used in actual bridges only affect nearly symmetric vibrations of cables, while having little impact on nearly antisymmetric vibrations. The effect of cable sags will reduce the optimal damping coefficient and inertial mass of the inertial mass damper for the first symmetric mode of the cable.

Sarcomere length control in striated muscle

1982 ◽  
Vol 242 (3) ◽  
pp. H411-H420 ◽  
Author(s):  
R. van Heuningen ◽  
W. H. Rijnsburger ◽  
H. E. ter Keurs
Keyword(s):  
Sarcomere Length ◽  
Striated Muscle ◽  
Feedforward Control ◽  
Muscle Length ◽  
Transient Behavior ◽  
Loop Filter ◽  
Internal Position ◽  
Optimal Damping ◽  
Internal Velocity ◽  
Muscle Responses

A system that makes control of muscle length (ML), sarcomere length (SL), and force (F) possible in striated muscle preparations is described. SL was measured by light diffraction techniques and two diffractometers. Control was performed by influencing ML with a penmotor system with a frequency response of 190 Hz. SL or F could be controlled by interrupting the internal position (i.e., ML) feedback of the motor and by closing the respective loop. Velocity feedback of the motor through an internal velocity coil was maintained in all cases for optimal damping. Steady-state error of the system was minimized by an integrating loop filter. The feedback path was selected by means of potentiometers or analog switches. Electronic stops in the circuit protected the muscle against excessive stretch and load. A microprocessor-based average-response computer could be used for feedforward control to eliminate noise or to analyze longitudinal uniformity of the muscle. Responses of rat cardiac trabeculae during SL and F control are shown. Transient behavior of SL and F during control and measures to eliminate the transients are discussed.

scholarly journals A Cable-Passive Damper System for Sway and Skew Motion Control of a Crane Spreader

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
La Duc Viet ◽  
Youngjin Park
Keyword(s):  
Motion Control ◽  
Input Shaping ◽  
Passive System ◽  
Time Integral ◽  
Passive Damper ◽  
Optimal Damping ◽  
Control Command ◽  
System Energy ◽  
Energy Dissipated ◽  
Input Shaping Control

While the crane control problem is often approached by applying a certain active control command to some parts of the crane, this paper proposes a cable-passive damper system to reduce the vibration of a four-cable suspended crane spreader. The residual sway and skew motions of a crane spreader always produce the angle deflections between the crane cables and the crane spreader. The idea in this paper is to convert those deflections into energy dissipated by the viscous dampers, which connect the cables and the spreader. The proposed damper system is effective in reducing spreader sway and skew motions. Moreover, the optimal damping coefficient can be found analytically by minimizing the time integral of system energy. The numerical simulations show that the proposed passive system can assist the input shaping control of the trolley motion in reducing both sway and skew responses.

scholarly journals THE DYNAMIC CHARACTERISTICS OF VEHICLE SUSPENSION SYSTEMS WITH OPTIMAL DAMPING

2015 ◽  
Vol 23 (03) ◽  
pp. 93-96
Author(s):  
Sergey Sergeevich Vorobyev ◽  
◽  
Sergey Aleksandrovich Vorobyev ◽  
Andrey Stanislavovich Reshenkin ◽  
Roman Aleksandrovich Goncharov ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Vehicle Suspension ◽  
Suspension Systems ◽  
Optimal Damping

Selective Control of Base-Isolated Structures with CS Dampers

2000 ◽  
Vol 16 (3) ◽  
pp. 593-606 ◽  
Author(s):  
J. Gluck ◽  
Y. Ribakov ◽  
A. N. Dancygier
Keyword(s):  
Mechanical Properties ◽  
Control Approach ◽  
Numerical Example ◽  
Actual Application ◽  
Selective Control ◽  
Base Isolator ◽  
Optimal Damping ◽  
Isolated Structures ◽  
Base Displacement ◽  
Controlled Structures

Addition of dampers to a base isolator reduces base displacements but may increase floor accelerations and interstory drifts. This paper presents a “selective control approach” for the design of base-isolated active controlled structures with Controlled Stiffness Dampers (CSD). According to this approach the dampers are activated only within a given range of the base displacement. The optimal damping forces are calculated according to structure's displacements and velocities. However, because of the CS dampers' structure the actual application of the forces is independent of the displacement and the velocity that are transferred to the device. These forces depend only on the geometry and on the mechanical properties of the devices' springs. The efficiency of the proposed method is demonstrated in a numerical example.

Optimal Damping Constant Investigation on a Quarter-Car

2013 ◽  
pp. 675-689
Author(s):  
Mihai Tica ◽  
George Dobre ◽  
Gabriele Barbaraci ◽  
Gabriele Virzi’ Mariotti
Keyword(s):  
Optimal Damping ◽  
Quarter Car

scholarly journals Optimal damping coefficient for a class of continuous contact models

2020 ◽  
Vol 50 (2) ◽  
pp. 169-188
Author(s):  
Mohammad Poursina ◽  
Parviz E. Nikravesh
Keyword(s):  
Contact Force ◽  
Analytical Formula ◽  
Coefficient Of Restitution ◽  
Damping Coefficient ◽  
Optimization Strategy ◽  
Continuous Contact ◽  
Optimal Damping ◽  
Wide Range ◽  
Contact Models ◽  
The Impact

Abstract In this study, we develop an analytical formula to approximate the damping coefficient as a function of the coefficient of restitution for a class of continuous contact models. The contact force is generated by a logical point-to-point force element consisting of a linear damper connected in parallel to a spring with Hertz force–penetration characteristic, while the exponent of deformation of the Hertz spring can vary between one and two. In this nonlinear model, it is assumed that the bodies start to separate when the contact force becomes zero. After separation, either the restitution continues or a permanent penetration is achieved. Therefore, this model is capable of addressing a wide range of impact problems. Herein, we apply an optimization strategy on the solution of the equations governing the dynamics of the penetration, ensuring that the desired restitution is reproduced at the time of separation. Furthermore, based on the results of the optimization process along with analytical investigations, the resulting optimal damping coefficient is analytically expressed at the time of impact in terms of system properties such as the effective mass, penetration velocity just before the impact, coefficient of restitution, and the characteristics of the Hertz spring model.

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