3. Semi- active MR damper
what is the Semi-active control
Smart damping technology
Algorithm and Control Strategy
for Semi-active
new control algorithm
Numerical examples
4. Semi- active MR damper
In recent years, due to developments in design technology and material qualities in civil
engineering, the structures become more light and slender. his will cause the structures to be
subjected to severe structural vibrations when they are located in environments where
earthquakes or high winds occur
these vibrations may lead to serious structural damage and potential failure.
Structural sustainability can be achieved by adding a mechanical system that is installed in
the structure to reduce vibrations. he vibrations can be controlled by various means, such as
modifying rigidities, masses, damping, or shape, and by providing passive or active counter
forces
Structural control methods that can be used include passive control systems, active control
systems, and semiactive control systems
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5. Semi- active MR damper
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Passive:
1. No need of external power source
2. Simple, in xpensive and reliable isolation
3. Inherent performance limitations
Active:
1. Control forces change with
excitation and response characteristics
1. Need of external energy source
2. Can supply and dissipate energy
Semi-active:
1. Excellent
compromise
between passive and
active systems
2. Require low power
for signal processing
3. Improved vibration
isolation
Semi-active control device has
stability and reliability of passive and
adaptability of active system.
8. Semi- active MR damper
Magnetorheological (MR) fluid dampers:
new class of semi-active control devices that utilize MR fluids to provide
controllable damping forces.
MR damper-based control strategies
• Reliability of passive control devices
• Versatility and adaptability of fully active control system
Attractive features
• Bounded-input, bounded-output stability
• Small energy requirements
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9. Semi- active MR damper
Smart damping technology is a type of semi-
active control that employs variable dampers, for
example, variable orifice dampers
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A high
magnetic field creates
a nearly unyielding
damper filled with a
semisolid fluid while
no magnetic field
produces an ordinary
viscous damper.
1. magnetorheological (MR) fluid
dampers,
2. and electrorheological (ER) fluid
dampers
10. Semi- active MR damper
A magneto rheological fluid (MR fluid) is a type of smart fluid in a carrier fluid,
usually a type of oil. When subjected to a magnetic field, the fluid greatly increases
its apparent viscosity, to the point of becoming a visco-elastic solid. Importantly, the
yield stress of the fluid when in its active ("on") state can be controlled very
accurately by varying the magnetic field intensity. The upshot of which is that the
fluid's ability to transmit force can be controlled with an electromagnet, which gives
rise to its many possible control-based applications.
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11. Semi- active MR damper
1. Under a strong magnetic field its viscosity can be increased by more than two orders of
magnitude in a very short time (milliseconds) Hence, very low response time.
2. The change in viscosity is continuous and highly reversible.
3. Yield strength of up to 50-100 kPa.
4. Insensitivity to contaminants.
5. Low voltage (12-24 V) required for operation.
6. Broad working temperature range : -40º C to 150º C.
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12. Semi- active MR damper
The magnetic particles, which are typically micrometer or nanometer scale spheres
or ellipsoids, are suspended within the carrier oil are distributed randomly and in
suspension under normal circumstances, as below.
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13. Semi- active MR damper
When a magnetic field is applied, however, the microscopic particles (usually in the 0.1–10
µm range) align themselves along the lines of magnetic flux. When the fluid is contained
between two poles (typically of separation 0.5–2 mm in the majority of devices), the
resulting chains of particles restrict the movement of the fluid, perpendicular to the direction
of flux, effectively increasing its viscosity.
Importantly, mechanical properties of the fluid in its “on” state are anisotropic. Thus in
designing a magneto rheological (or MR) device, it is crucial to ensure that the lines of flux
are perpendicular to the direction of the motion to be restricted.
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14. Semi- active MR damper
MR fluid is composed of oil and varying percentages of iron particles that have been
coated with an anti-coagulant material
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Without Magnetic field With Magnetic field
The MR fluid inside MR dampers is
a suspension of micrometer-sized
magnetic particles in a carrier
fluid. Upon exposure to a
magnetic field, the free-flowing
linear viscous MR fluid can
change to a semi-solid with
controllable yield stress in
milliseconds
15. Semi- active MR damper
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a. Valve mode
b. Shear mode
c. Squeeze mode
16. Semi- active MR damper
Squeeze mode has a thin film (on the order of 0.020 in.) of MR fluid that is sandwiched
between paramagnetic pole surfaces as shown in Figure-
The distance between the parallel pole
plates changes, which causes a squeeze flow.
Suitable for relatively high dynamic forces
with small amplitudes (few mm).
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17. Semi- active MR damper
It differs in operation from squeeze mode due to moving paramagnetic sliding or rotating
surfaces. It has thin layer( 0.015 in.) of MR fluid sandwiched between paramagnetic
surfaces.
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1. Magnetic field is perpendicular to
the direction of motion of these
moving surfaces.
2. Examples of shear mode include
clutches, brakes, chucking and
locking devices, dampers and
structural composites.
3. Suitable for relatively small force
applications.
18. Semi- active MR damper
It is the most widely used of three modes. Here the two reservoirs of MR fluid are used and
magnetic field is used to impede the flow of MR fluid from one reservoir to another. Here
the flow can be achieved by pressure drop between reservoirs and flow resistance can be
controlled by magnetic field.
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These devices
generally operate in
the valve mode
19. Semi- active MR damper
Mechanical Engineering
Military and Defense
Optics
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motor damping, operator seat/cab damping in
construction vehicles, and more
body armor, helicopters, and various other all-
terrain vehicles employ dynamic MR shock
absorbers
Hubble Space Telescope's corrective lens
20. Semi- active MR damper
Automotive and Aerospace
Human Prosthesis
seismic control
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shock absorbers of a vehicle's suspension
human prosthetic legs
Building
Frame
Bridge
Suspended bridge
Base isolation
resonant response
In the past decade, magnetorheological (MR)
fluid and MR damping devices have been
extensively investigated. Among the various
applications of MR fluid, MR dampers have
gained considerable attentions in vibration
control of civil and mechanical structures.
21. Semi- active MR damper
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A MR damper offers a highly reliable mechanism for response
reduction at a modest cost, and is fail-safe because the damper
becomes passive if the control hardware breaks down
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The results verify that the seismic response reduction experimental method is feasible and the good
performance of seismic longitudinal response reduction of the suspension bridge can be achieved
by MR damper.
25. Semi- active MR damper
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hybrid base isolation
system with semi-active devices, like MR dampers
Passive high-damping devices incorporated within the isolation system can control large
bearing displacements associated with pulse-like earthquake ground motions, but the
beneficial effects of the base isolation system may be significantly reduced for both moderate
and strong earthquakes due to the transfer of energy into higher modes which can result in
increased inter story drift and floor acceleration responses
27. Semi- active MR damper
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To reduce the resonant response
of high-speed railway bridges,
semi-active magnetorheological
dampers are proposed
a combination of a
double-beam system and
MR dampers is proposed
in this work that permits
installing the dampers
closer to, and even at the
exact location of the
main beam antinodes.
28. Semi- active MR damper
High density, due to presence of iron, makes them heavy. However,
operating volumes are small, so while this is a problem, it is not
insurmountable.
High-quality fluids are expensive.
Fluids are subject to thickening after prolonged use and need replacing.
Settling of ferro-particles can be a problem for some application
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29. Semi- active MR damper
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• Requirement of external power,
controller, sensors
• Complication of networks using
many MR dampers
for large-scale structure
• Difficulties to install and
maintain
؟
30. Semi- active MR damper
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Without MagneticFields
With
Magnetic
Fields
Without
Magnetic
Fields
With Magnetic Fields
31. Semi- active MR damper
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Control Law
MR
Damper
Structure
Decision
Block
Nominal
Controller
f f
cf
f
u
y
gx
dd x,x
One of the challenges in the
application of the MR dampers is to
develop
an effective control strategy that
can fully exploit the capabilities of
the MR dampers
32. Semi- active MR damper
اغلبیتمرالگوهایلکنترنیمهفعالبراساساییرمیمتغییرمطالعهشدهاند.یتمرالگوهایمختلفیایربانواعمیراگرهاتوسعهپیدا
کردهاندکهشامله:
.1شورلکنترغیرمتمرکزبنگبنگbang-bang control
.2لکنتربهینهکوتاهclipped-optimal control
.3لکنترمدلاصککاکهمگنhomogeneous friction control
.4لکنترنیمهفعالاربراساسیتمرالگوهایعصبیneural network control
.5لکنتریفازیپایدارلیاپونوLyapunov theory
.6لکنتریفازfuzzy control theory
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Another challenges in the application of the
MR dampers is
using an appropriate control algorithm to
determine the command
voltage of the MR damper
ک هایالگوریتم سایرلیاپونویپایدارروش بجزلنتر
م حلاز آنها درکه،اند شدهبنا یکاتیراساسرباتریس
بهین لکنترنیرویدنرآو بدستجهت یکاتیره
است شده استفاده
33. Semi- active MR damper
a new control algorithm to command an MR damper implemented:
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inspired by a quasi-bang-bang
controller
fuzzy logic
controller
he proposed controller shows its capability
in reducing all floors’ absolute accelerations as well
as inter story drifts, in addition to requiring a
minimum control force.
34. Semi- active MR damper
the following assumptions are considered for a shear building model:
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Equation of Motion
Using Newton’s second law of
motion, the equation of motion
may be written as follows
35. Semi- active MR damper
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an order differential equation may be expressed by a first-order vector-matrix differential
equation as follows:
36. Semi- active MR damper
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THe approach is inspired by the quasi bang-bang
controller; however, the proposed method gives
weights to the output in a way that is similar to a fuzzy
logic controller. In addition to commanding the
current driver of the MR damper with the values 0
(minimum voltage) and max (maximum voltage), the
proposed controller makes use of the values in
between. he control algorithm is expressed as
follows:
SEMI-ACTIVE CONTROL
ALGORITHMS
the physical properties of the primary structure, as well as
the type of the excitation input (earthquake or wind),
37. Semi- active MR damper
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he input ground acceleration used in the current study is the
one-dimensional component of the 1940 El Centro earthquake
38. Semi- active MR damper
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In this section, a three-story shear
type building structure employing
an MR damper is presented. The
goal is to evaluate the performance
of the semi-active nonlinear fuzzy
control system. A typical example of
a building structure employing an
MR damper is depicted in
In this building structure, a SD-1000 MR damper has
been applied whose parameters are given in Table
39. Semi- active MR damper
the force predicted by the model is given by
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1. Controller Based on Lyapunov
Stability theory
2. Decentralized Bang-Bang Controller
3. Clipped-Optimal Controller
4. Modulated Homogeneous Friction
Controller
5. Maximum Energy Dissipation
Controller
6. Quasi-Bang-Bang Controller
41. Semi- active MR damper
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he input ground acceleration used in the current study is the one-dimensional
component of the 1940 El Centro earthquake
44. Semi- active MR damper
Table 1 lists the peak responses of the building model, when subjected to the north-south
component of the 1940 EL Centro earthquake signals. In the table, uncontrolled case means
that the MR damper was not implemented in the building model. Passive-of and passive-on
mean that the input voltage to the current driver of the MR damper is set to zero and to the
maximum value (max = 2.25 volt), respectively. It is shown that the MR damper with both
passive-of and passive-on control cases is capable of reducing the structural responses over
the uncontrolled case. The passive-on case is better than the passive-of case in reducing the
maximum displacements. However, the passive-of case is better than the passive-on case in
reducing the maximum absolute accelerations. he results of the uncontrolled, the passive-of,
and the passive-on cases are similar to those presented in.
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45. Semi- active MR damper
he results listed in Table 1 show that, for all the controllers presented, Lyapunov controller B and the
quasi-bangbang controller provide the best reduction in the maximum floor displacement (Xn).
Considering the maximum absolute acceleration of the passive-of case as a reference, the Lyapunov
controller B increased the response by 7.% while the quasi-bang-bang controller did not show
signiicant reduction. the decentralized bang-bang controller provides an excellent reduction in the
absolute floor accelerations; however, it is not able to reduce the displacements over the passive-on
case. the clipped-optimal control algorithm gives a high reduction in both the inter-story drits and the
maximum floor displacements; also, it gives a good reduction in the maximum absolute accelerations.
A time domain comparison among all the controllers used is shown in Figure 8. the comparison shows
the capability of the proposed controller in reducing the absolute acceleration response over all the
controllers presented in the literature.
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47. Semi- active MR damper
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Semi-active MR dampers for reducing response
of high-speed railway bridges
48. Semi- active MR damper
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Jiang and Christenson (2010) proposed the use of MR dampers to reduce the dynamic
response of existing highway bridges. Initial experimental tests to validate some
simulations were performed. The results showed that the effectiveness of MR dampers
was limited and the displacement response of the bridge was only reduced about 17%.
This is due to the fact that the MR dampers were installed far from the antinodes of the
controlled mode shapes and the control algorithm to drive the MR dampers was not
robust enough in this study.
49. Semi- active MR damper
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Therefore, in order to make MR dampers more effective
The Bouc–Wen
50. Semi- active MR damper
the railway excitation has been simulated using a moving load model , and vehicle–structure
inter action has been neglected.
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51. Semi- active MR damper
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The auxiliary beams, which are
connected to the main beams
through the MR dampers shown in
Fig. are considered as steel box
girders with constant cross section
inside which the dampers are to be
installed. The dimensions of the
auxiliary beams are determined
based on guaranteeing the
accomplishment of the Serviceability
Limit State of vertical acceleration of
the main beams (bridges)
52. Semi- active MR damper
The Bouc–Wen model is based on a phenomenological model (Spencer etal.,1997), which is
described by the following
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53. Semi- active MR damper
An inverse model of MR dampers as one part of a damping force control scheme is a model
that predicts a control input voltage signal for a given displacement, velocity and force. The
predicted input voltage, which is input to MR dampers, is used to produce the desired force,
which is the purpose of the control strategy.
In this section, the adaptive neuro-fuzzy inference system technology (ANFIS) as
implemented in the Fuzzy Logic Toolbox in MATLAB is used to build the inverse model
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57. Semi- active MR damper
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Of the 40,000 original data sets,
14,000 are used as training data
while the remaining data is used
for evaluation purposes. After
several trials, the best results as
indicated in Fig. 7 obtained.
58. Semi- active MR damper
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Fig. 8 represents the control system defined,
where wi and ui are the modal external load
and the modal control force, respectively; z0i
is the controlled out put, containing the para-
meters to be minimized; zci is the control
force that is refined by a filter Wci(s); and yi is
the measured data. The weighting function
Wci (s) is a low-pass filter (LPF)in order to
improve the tracking ability of the magneto-
rheological dampers. This function
concentrates the control force on a defined
frequency range.
61. Semi- active MR damper
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the results show that the maximum acceleration of
the main beam is reduced about 66.64% when
compared to the acceleration of the bare
structure subjected to the train passage at the
resonant speed of v=287.33km/h
62. Semi- active MR damper
In order to evaluate the performance of the semi-active controller with MR dampers, three
situations are considered in which the MR damper is employed in a passive-off, passive-on
and semi - active mode
In the case of the passive-off mode, the voltage command to the MR dampers is set at 0 V
and in the passive-on mode, it is set at the maximum voltage level (12 V)
Besides, the effectiveness of MR dampers is also clarified through the comparison with a
hypothetical retrofit using one equivalent fluid viscous damper in the same configuration
and using the same auxiliary beam
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64. Semi- active MR damper
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These results show again the effectiveness of the active and semi-
active dampers. Besides, it can be seen that the reduction of
acceleration is higher than that of displacements in the semi-active
and active control cases.
Another interesting issue withdrawn from these results is that the forces
applied by the MR damper operating in semi-active mode are always
smaller than those corresponding to the damper operating in the passive-
on mode with a maximum input voltage 12 V.
It is indicated that higher damping
forces are not always associated
with better results.
10%
65. Semi- active MR damper
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the acceleration
66. Semi- active MR damper
Semi-active control strategies combine active and passive control schemes and attempt to
offer the advantages of both systems with better performance
Semi-active control device has stability and reliability of passive and adaptability of active
system
Structural property estimation, modeling errors and time- variant material properties, which
lead to detuning, may affect the control effectiveness of MR dampers
Smart damping technology assumes the positive aspects of both passive and active control
devices; it can provide increased performance over passive control without the concerns of
energy and stability associated with active control
study shows that the MR damper is highly controllable in a manner that permits a designer
to achieve different control objectives.
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67. Semi- active MR damper
very little study has been done with regard to the effect of non-uniform distribution of the
dampers
no solution for the optimal arrangement was provided
found that the adaptive feature of a fuzzy controller has various advantages in the control of
a building including a MR damper system
genetic algorithms (GA) as an optimization tool in designing control systems for the output
voltage of MR dampers achieve enhanced seismic performance with economical efficiency
Further research is recommended to apply for the larger-scale building structures equipped
with many MR dampers.
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The door is open for interested researchers to come up with new methodology
68. Semi- active MR damper
1. A magnetorheological damper capable of force and displacement sensing K.H. Lama, Z.H. Chena,
Y.Q. Nia,∗, H.L.W. Chanb, Sensors and Actuators A 158 (2010) 51–59,
2. An experimental study on using MR damper to mitigate longitudinal seismic response of a
suspension bridge, Meng-Gang Yang a,n, Zheng-QingChen b, Xu-GangHua, Soil Dynamics and
Earthquake Engineering 31 (2011) 1171–1181
3. Application of semi-active control strategies for seismic protection of buildings with MR dampers,
Maryam Bitaraf, Osman E. Ozbulut, Stefan Hurlebaus , Luciana Barroso, Engineering Structures 32
(2010) 30403047
4. Hierarchical semi-active control of base-isolated structures using a new inverse model of
magnetorheological dampers, Arash Bahar a, Francesc Pozo b,*, Leonardo Acho b, José Rodellar a,
Alex Barbat, Computers and Structures 88 (2010) 483–496
5. Optimal control of structural vibrations using a mixed-mode magnetorheological fluid mount,
Seung-Bok Choi, Sung-Ryong Hong, Kum-Gil Sung, Jung-Woo Sohn, International Journal of
Mechanical Sciences 50 (2008) 559–568
6. Optimal control of structures with semiactive tuned mass dampers, U. Aldemir, Journal of Sound
and Vibration 266 (2003) 847–874
7. Optimal design of semi active control for adjacent buildings connected by MR damper based on
integrated fuzzy logic and multi-objective genetic algorithm, Mehmet E. Uz, Muhammad N.S.
Hadi, Engineering Structures 69 (2014) 135–148
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69. Semi- active MR damper
8. Semi-active magnetorheological dampers for reducing response of high-speed railway bridges, M. Luu
a,n, M.D.Martinez-Rodrigo b, V.Zabel a, C.Könke, Control EngineeringPractice32(2014)147–160
9. Semiactive nonlinear control of a building with a magnetorheological damper system, YeesockKim a,
RezaLangari b, StefanHurlebaus , Mechanical Systems and Signal Processing 23 (2009) 300–315
10. Vibration Control of Buildings Using Magnetorheological Damper: A New Control Algorithm,
AlyMousaad Aly, Hindawi Publishing Corporation Journal of Engineering Volume 2013, Article ID
596078, 10 pages http://dx.doi.org/10.1155/2013/596078
11. Fuzzy-PID Controller for Semi-Active Vibration Control Using Magnetorheological Fluid Damper,
Banna Kasemi *, Asan G. A. Muthalif , M. Mahbubur Rashid, Sharmila Fathima, Procedia Engineering
41 ( 2012 ) 1221 – 1227
12. Semi-Active Control of a Benchmark Building using Neuro-Inverse Dynamics of MR Damper, Irfan H.
Vadtalaa, Devesh P. Sonib , Dolarray. G. Panchalc, Chemical, Civil and Mechanical Engineering Tracks
of 3rd Nirma University International Conference(NUiCONE 2012)
13. Design, modeling and testing of magnetorheological (MR) dampers using analytical flow solutions,
Weng W. Chooi, S. Olutunde Oyadiji, Computers and Structures 86 (2008) 473–482
14. Increasing Resilience in Civil Structures Using Smart Damping Technology Zhaoshuo Jiang, Ph.D.
University of Connecticut, 2012, Submitted in Partial Fulfillment of the Requirements for the Degree of
Doctor of Philosophy at the University of Connecticut
15. Squeezing Force of the Magnetorheological Fluid Isolating Damper for Centrifugal Fan in Nuclear
Power Plant, Jin Huang,1, 2 PingWang,1 and GuochaoWang1, Science and Technology of Nuclear
Installations Volume 2012, Article ID 175703, 6 pages
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70. Semi- active MR damper
16. Semi-active control using magnetorhelogical dampers with output feedback and
distributed sensing, N.K. Chandiramani∗ and S.P. Purohit, Shock and Vibration 19 (2012)
1427–1443
17. SEISMIC ANALYSIS OF STRUCTURES T. K. Datta Indian Institute of Technology Delhi, India,
Copyright 2010 John Wiley & Sons (Asia) Pte Ltd, 2 Clementi Loop, # 02-01
18. Civil Engineering Applications of Vibration Control (Structural Control) Naresh K. Chandiramani,
Associate Professor Room 141, Dept. of Civil Engineering
19. Magneto-rheological Dampers Ameya Sanjay Dahale College of Engineering, Pune. B. Tech
Mechanical Engineering MIS 111010040
20. MATERIAL TECHNOLOGY NEWLY DEVELOPED ENGINEERING MATERIAL
21. Mathematical Modeling and Simulation of SAS System With Magnetorheological (MR) Damper
University of Agder-Spring 2013Oreste Niyonsaba Dimuthu Dharshana Arachchige Subodha
Tharangi Ireshika
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