U.S. patent application number 13/874921 was filed with the patent office on 2014-11-06 for systems and methods for damping building oscillations.
The applicant listed for this patent is Elwha LLC. Invention is credited to Jeffrey A. Bowers, Alistair K. Chan, Bran Ferren, W. Daniel Hillis, Roderick A. Hyde, Cameron A. Myhrvold, Conor L. Myhrvold, Nathan P. Myhrvold, Tony S. Pan, Clarence T. Tegreene, Lowell L. Wood,, JR..
Application Number | 20140325922 13/874921 |
Document ID | / |
Family ID | 51840673 |
Filed Date | 2014-11-06 |
United States Patent
Application |
20140325922 |
Kind Code |
A1 |
Bowers; Jeffrey A. ; et
al. |
November 6, 2014 |
SYSTEMS AND METHODS FOR DAMPING BUILDING OSCILLATIONS
Abstract
A fluid transport system for actively damping oscillations of a
structure affixed to a ground surface is disclosed. The system
includes a pipe defining a flow path, a driver in fluid
communication with the pipe and configured to provide a fluid flow
through the pipe, and a controller. The controller is programmed to
send a fluid flow command signal in response to an event signal
indicating an oscillation event.
Inventors: |
Bowers; Jeffrey A.;
(Issaquah, WA) ; Chan; Alistair K.; (Bainbridge
Island, WA) ; Ferren; Bran; (Beverly Hills, CA)
; Hillis; W. Daniel; (Encino, CA) ; Hyde; Roderick
A.; (Redmond, WA) ; Myhrvold; Cameron A.;
(Bellevue, WA) ; Myhrvold; Conor L.; (Bellevue,
WA) ; Myhrvold; Nathan P.; (Bellevue, WA) ;
Pan; Tony S.; (Cambridge, MA) ; Tegreene; Clarence
T.; (Mercer Island, WA) ; Wood,, JR.; Lowell L.;
(Bellevue, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Elwha LLC; |
|
|
US |
|
|
Family ID: |
51840673 |
Appl. No.: |
13/874921 |
Filed: |
May 1, 2013 |
Current U.S.
Class: |
52/167.2 |
Current CPC
Class: |
E04H 9/02 20130101; E04H
9/0215 20200501; E04H 9/0235 20200501 |
Class at
Publication: |
52/167.2 |
International
Class: |
E04B 1/98 20060101
E04B001/98; E04H 9/02 20060101 E04H009/02 |
Claims
1. A fluid transport system for actively damping oscillations of a
structure affixed to a ground surface, comprising: a pipe defining
a flow path; a driver in fluid communication with the pipe and
configured to provide a fluid flow through the pipe; and a
controller programmed to send a fluid flow command signal in
response to an event signal indicating an oscillation event.
2-20. (canceled)
21. The system of claim 1, further comprising a sensor operatively
coupled to the controller.
22. The system of claim 21, further comprising a module, wherein
the sensor is configured to provide a sensor signal to the
module.
23. The system of claim 22, wherein the module provides the event
signal to the controller when the sensor signal exceeds a threshold
level.
24-54. (canceled)
55. The system of claim 1, further comprising a first tank in fluid
communication with the driver.
56. The system of claim 55, wherein the first tank is in fluid
communication with the pipe.
57-62. (canceled)
63. The system of claim 55, wherein the first tank is coupled to
the structure.
64. (canceled)
65. The system of claim 63, further comprising a second tank in
fluid communication with the driver.
66. The system of claim 65, wherein the second tank is in fluid
communication with the pipe.
67. The system of claim 66, wherein the first tank is in fluid
communication with the second tank via the pipe.
68-81. (canceled)
82. An active damping system for a structure affixed to a ground
surface, comprising: a driver; a fluid outlet configured to be
coupled along an outer surface of the structure in an elevated
location relative to the ground surface; a connection pipe coupled
to the driver and the fluid outlet and defining a flow path; and a
controller programmed to send a fluid flow command signal in
response to an event signal indicating an oscillation event.
83. The system of claim 82, wherein the controller is configured to
control the driver using the fluid flow command signal.
84-85. (canceled)
86. The system of claim 82, further comprising a valve positioned
within the flow path.
87-93. (canceled)
94. The system of claim 82, further comprising a second fluid
outlet, the second fluid outlet configured to be coupled along the
outer surface of the structure.
95-108. (canceled)
109. The system of claim 94, further comprising a second connection
pipe coupled to the driver and the second fluid outlet, the second
connection pipe defining a second flow path.
110. The system of claim 109, further comprising a valve, wherein
the controller is programmed to selectively actuate the valve
between a first position and a second position.
111-113. (canceled)
114. The system of claim 110, further comprising a pressurized
container configured to store a pressurized fluid.
115. (canceled)
116. The system of claim 114, wherein the valve directs a fluid
flow from the pressurized container to the first fluid outlet when
in the first position.
117. The system of claim 114, wherein the valve directs a fluid
flow from the pressurized container to the second fluid outlet when
in the second position.
118. The system of claim 109, further comprising a first valve
coupled along the first flow path and a second valve coupled along
the second flow path.
119. The system of claim 118, wherein the fluid flow command signal
is configured to selectively actuate the first valve and the second
valve between a first position and a second position.
120-195. (canceled)
196. A structure affixed to a ground surface, comprising: a
structural frame; a pipe coupled to the structural frame, the pipe
defining a flow path; a driver in fluid communication with the pipe
and configured to provide a fluid flow through the pipe; and a
controller programmed to send a fluid flow command signal in
response to an event signal indicating an oscillation event.
197-221. (canceled)
222. The structure of claim 196, further comprising a fluid outlet
coupled along an outer surface of the structure in an elevated
location relative to the ground surface, wherein the pipe extends
between the driver and the fluid outlet and defines a flow
path.
223. The structure of claim 222, further comprising a second fluid
outlet coupled along the outer surface of the structure.
224. The structure of claim 223, wherein the first fluid outlet and
the second fluid outlet are positioned at different vertical
locations of the structure.
225-230. (canceled)
231. The structure of claim 223, wherein the first fluid outlet
defines a first fluid flow direction and the second fluid outlet
defines a second fluid flow direction.
232. (canceled)
233. The structure of claim 231, wherein the first fluid flow
direction opposes the second fluid flow direction.
234-262. (canceled)
263. The structure of claim 196, further comprising a first tank in
fluid communication with the driver.
264-270. (canceled)
271. The structure of claim 263, wherein the first tank is coupled
to the structural frame.
272-273. (canceled)
274. The structure of claim 271, further comprising a second tank
in fluid communication with the driver.
275-276. (canceled)
277. The structure of claim 274, wherein the first tank is
positioned at a first vertical location of the structure and the
second tank is positioned at a second vertical location of the
structure.
278. The structure of claim 274, wherein the second tank is offset
from a centerline of the structure.
279. The structure of claim 278, wherein the first tank is
positioned on a first side of the structure and the second tank is
positioned on a second side of the structure.
280-291. (canceled)
292. The structure of claim 196, wherein the pipe comprises a
damping pipe.
293. The structure of claim 292, wherein the damping pipe includes
a linear section positioned along a first axis of the
structure.
294-422. (canceled)
Description
BACKGROUND
[0001] Structures, such as buildings, bridges, and underwater
superstructures, experience unique loading conditions during
adverse weather conditions or seismic events. Such wind or seismic
loading imposes constant, periodic, or irregular forces on the
frame members of the structure. These forces displace at least a
portion of the frame members. A structure may fail (i.e.
plastically deform, collapse, etc.) where the displacement in the
frame members exceeds a structural limit for the frame members,
joints, and other components of the structure. A structure may
utilize one or more damping systems to reduce the likelihood of
failure.
[0002] Traditional methods for preventing a structure from failing
include designed elasticity, passive damping systems, and viscous
damping. Designed elasticity is often included as part of the
initial design process of the structure and involves strategically
positioning frame members to create an at least partially flexible
structure. For a structure having designed elasticity, an input
force may displace frame members without plastically deforming the
structure. Passive damping systems similarly prevent a structure
from failing but incorporate a passive system designed to reduce
displacement of the frame members. By way of example, a building
may include a weight positioned in an elevated position to
counteract building sway. However, these systems are most
efficiently installed during the initial design and construction of
the structure thereby rendering them of reduced applicability to
previously erected structures.
[0003] Other passive damping systems include damping devices (e.g.,
elastomeric isolators, isolation bearings, etc.) positioned within
the structure or between the structure and a ground volume to
reduce displacement of the structure. Viscous damping utilizes
dampers positioned between frame members to dissipate energy and
reduce displacement of the structure. However, these systems are
most efficiently installed during the initial construction of the
structure, and a structure may require numerous damping devices to
reduce the displacement of frame members during adverse weather
conditions or seismic events.
SUMMARY
[0004] One exemplary embodiment relates to a fluid transport system
for actively damping oscillations of a structure affixed to a
ground surface. The system includes a pipe defining a flow path, a
driver in fluid communication with the pipe and configured to
provide a fluid flow through the pipe, and a controller. The
controller is programmed to send a fluid flow command signal in
response to an event signal indicating an oscillation event.
[0005] Another exemplary embodiment relates to an active damping
system for a structure affixed to a ground surface. The system
includes a driver and a fluid outlet, the fluid outlet configured
to be coupled along an outer surface of the structure in an
elevated location relative to the ground surface. The system also
includes a connection pipe extending between the driver and the
fluid outlet and defining a flow path and a controller. The
controller is programmed to send a fluid flow command signal in
response to an event signal indicating an oscillation event.
[0006] Still another exemplary embodiment relates to a structure
affixed to a ground surface. The structure includes a structural
frame, a pipe coupled to the structural frame, the pipe defining a
flow path, and a driver in fluid communication with the pipe and
configured to provide a fluid flow through the pipe. The structure
also includes a controller, and the controller is programmed to
send a fluid flow command signal in response to an event signal
indicating an oscillation event.
[0007] Yet another exemplary embodiment relates to a method for
actively damping a structure affixed to a ground surface by
transferring fluid. The method includes providing a pipe, the pipe
defining a flow path, providing a fluid flow through the pipe with
a driver, and sending a fluid flow command signal with a controller
in response to an event signal indicating an oscillation event.
[0008] The foregoing summary is illustrative only and is not
intended to be in any way limiting. In addition to the illustrative
aspects, embodiments, and features described above, further
aspects, embodiments, and features will become apparent by
reference to the drawings and the following detailed
description.
BRIEF DESCRIPTION OF THE FIGURES
[0009] FIG. 1 is an elevation view of a building.
[0010] FIG. 2 is an elevation view of a building having a damping
device that includes a damping tube, according to an exemplary
embodiment.
[0011] FIG. 3 is a side view of a building having a damping device
that includes a damping tube, according to an exemplary
embodiment.
[0012] FIG. 4 is an elevation view of a building having a damping
device that includes a tube defining a circular flow path,
according to an exemplary embodiment.
[0013] FIG. 5 is a side view of a building having a damping device
that includes a tube defining a circular flow path, according to an
exemplary embodiment.
[0014] FIG. 6 is an elevation view of a building having a damping
device that includes a non-linear damping tube, according to an
exemplary embodiment.
[0015] FIG. 7 is a side view of a building having a damping device
that includes fluid storage devices, according to an exemplary
embodiment.
[0016] FIG. 8 is an elevation view of a building having a damping
device that includes a plurality of fluid outlets, according to an
exemplary embodiment.
[0017] FIG. 9 is a side view of a building having a damping device
including a fluid storage device and configured to change a mode of
the building, according to an exemplary embodiment.
[0018] FIG. 10 is a side view of a building having a damping device
including two fluid storage devices and configured to change a mode
of the building, according to an exemplary embodiment.
[0019] FIG. 11 is a side view of a building having a damping device
including two fluid storage devices and an elevated fluid flow
device, according to an exemplary embodiment.
DETAILED DESCRIPTION
[0020] In the following detailed description, reference is made to
the accompanying drawings, which form a part hereof. In the
drawings, similar symbols typically identify similar components,
unless context dictates otherwise. The illustrative embodiments
described in the detailed description, drawings, and claims are not
meant to be limiting. Other embodiments may be utilized, and other
changes may be made, without departing from the spirit or scope of
the subject matter presented here.
[0021] The damping systems described herein are intended to reduce
the displacement of frame members within a structure during adverse
weather conditions and seismic loading. Specifically, a system
employing fluid active damping is intended to reduce the
displacement of frame members within a structure by providing a
force to counter wind and seismic loading. Damping systems may
include lengths of pipe, tanks, or other structures that provide a
fluid flow therethrough providing a countering force. In other
embodiments, damping systems locate a fluid in different positions
to change the fundamental period of the building. The fluid damping
devices described herein are intended to offer various advantages
relative to existing damping systems. Such advantages include,
among others, the ability to deliver the fluid into numerous
orientations within the structure, provide variable damping forces
by changing the fluid flow rate, and utilize the fluid for another
purpose (e.g., to provide water to operate fixtures within a
building, to provide a fluid as part of a fire suppression system,
etc.).
[0022] Further, the damping systems described herein may include a
sensor (e.g., geophone, accelerometer, etc.) to facilitate
real-time engagement of the damping system. Various control schemes
may be included to further reduce the displacement of frame members
within a structure during adverse weather conditions and seismic
loading. Such schemes are intended to actively damp oscillations of
a structure. Among other benefits, active fluid damping systems may
be installed during the initial construction of a structure or
retrofitted into existing structures.
[0023] Referring to the exemplary embodiment shown in FIG. 1, a
structure, shown as building 10, includes a base portion 12 that
interfaces with a ground volume 20. According to an exemplary
embodiment, base portion 12 includes a plurality of structural
members (e.g., pylons, pillars, etc.) extending into ground volume
20. In some embodiments, base portion 12 also includes a passive
damping system, such as isolation bearings, elastomeric isolators,
or other base-isolation systems. According to an alternative
embodiment, building 10 does not include base portion 12 and
instead includes another system that couples building 10 to ground
volume 20.
[0024] According to an exemplary embodiment, building 10 includes
an elevated portion 14 extending upwards from base portion 12. As
shown in FIG. 1, elevated portion 14 includes a constant,
rectangular cross section forming a prism. In other embodiments,
elevated portion 14 includes a variable cross-sectional shape or
forms another shape (e.g., trapezoidal, cylindrical, conical,
irregular, etc.). It should be understood that various factors
influence the shape of elevated portion 14. By way of example,
aesthetics, structural design considerations, or a purpose of
building 10 may produce an elevated portion 14 having a particular
shape.
[0025] According to an exemplary embodiment, elevated portion 14
includes a frame, shown as super structure 16. In some embodiments,
super structure 16 is designed to support the vertical weight loads
of building 10 including the weight of floors, occupants, office
spaces, structural beams, or still other elements. As shown in FIG.
1, super structure 16 is a three-dimensional network of support
elements 18. The various support elements 18 may be arranged in a
Type I arrangement having a semi-rigid or rigid fame, a Type II
arrangement having a frame and shear trusses or a shear band and
outrigger trusses, or a Type III arrangement forming an end channel
framed tube with interior shear trusses. According to an
alternative embodiment, super structure 16 includes a Type IV
arrangement of support elements 18 having an exterior framed tube,
a bundled framed tube, an exterior diagonalized tube, or a tubular
core. It should be understood that building 10 may include still
other combinations of support elements 18.
[0026] Referring next to the exemplary embodiment shown in FIGS.
2-3, a structure, shown as building 30, includes an elevated
portion 32 extending from and affixed to a ground surface 40.
According to an exemplary embodiment, building 30 includes a
damping device, shown as fluid damping device 50. In some
embodiments, fluid damping device 50 is provides damping forces to
building 30 during an oscillation event (e.g., seismic activity,
acceleration of the structure, displacement of at least a portion
of the structure greater than a threshold level, etc.). As shown in
FIG. 2, fluid damping device 50 includes a driver (i.e. flow
generator, pump, pressure source), shown as flow device 60 and a
tube (i.e. conduit, duct, pipe, etc.), shown as tube 70. Tube 70
may include a single pipe or several sections of pipe coupled
together (e.g., welded, secured, fastened, etc.). According to an
exemplary embodiment, tube 70 defines a flow path for a fluid. In
some embodiments, flow device 60 is positioned at a ground level of
building 30. In other embodiments, flow device 60 is located in an
elevated position (e.g., on a second story, at the top story,
between the ground level and top story, etc.) relative to ground
surface 40.
[0027] In some embodiments, flow device 60 is in fluid
communication with tube 70 and directs a fluid (e.g., water,
hydraulic oil, a mixture including sand and water, etc.) through
tube 70. According to an exemplary embodiment, flow device 60 is a
centrifugal pump that delivers the fluid at a fluid flow rate
(e.g., 100 gallons per minute, 100,000 gallons per minute, 300,000
gallons per minute, etc.). In some embodiments, flow device 60
includes an impeller that is rotated by an input device. Such an
input device may be an electric motor, a fossil fuel powered
engine, a liquid fueled rocket, a solid fueled rocket, compressed
air, or another system. According to an alternative embodiment,
flow device 60 is another type of pump. According to still another
alternative embodiment, flow device 60 is a compressed fluid (e.g.,
air, nitrogen, etc.) that propels a fluid through tube 70. In still
other alternative embodiments, flow device 60 is a tank that stores
a compressed fluid. Once activated, such a flow device 60 releases
the compressed fluid into tube 70.
[0028] As shown in FIGS. 2-3, tube 70 includes a linear section,
shown as damping portion 72, and a section extending between flow
device 60 and damping portion 72, shown as lift portion 74.
According to an exemplary embodiment, damping portion 72 includes a
first end and a second end. In some embodiments, a pressurized
fluid flows from flow device 60, through lift portion 74, and into
damping portion 72. As shown in FIGS. 2-3, the first end of damping
portion 72 is positioned along a first side of building 30 and the
second end of damping portion 72 is positioned along a second side
of building 30. According to an exemplary embodiment, lift portion
74 extends between the first end of damping portion 72 and flow
device 60. In alternative embodiments, tube 70 includes damping
portion 72 and lift portion 74 having different lengths than those
shown in FIGS. 2-3.
[0029] Referring to the exemplary embodiment shown in FIGS. 2-3, a
fluid flows from an inlet, shown as inlet tube 62, to damping
portion 72 through lift portion 74 upon activation of flow device
60. As shown in FIGS. 2-3, a fluid flowing from the first end to
the second end of damping portion 72 interacts with an end cap 73.
Such interaction imparts a force on end cap 73. In some
embodiments, tube 70 includes auxiliary devices (e.g., check
valves, vents, etc.) that facilitate such a fluid flow.
[0030] According to an exemplary embodiment, fluid damping device
50 reduces the oscillations of building 30 by delivering a fluid
through damping portion 72. As shown in FIGS. 2-3, damping portion
72 is coupled to a frame of building 30, a portion of which is
shown as super structure 80. According to an exemplary embodiment,
a fluid flowing within damping portion 72 along a first direction
will impart a damping force on super structure 80. A portion of the
damping force is related to the product of the volumetric flow
rate, the density, and the velocity of the fluid within damping
portion 72. Such values for the fluid at the second end of damping
portion 72 may be determined using the pressure of the fluid at an
outlet of flow device 60, pressure losses within tube 70, and the
lift head required to elevate the fluid from flow device 60, among
other considerations.
[0031] Referring next to the exemplary embodiment shown in FIGS.
4-5, fluid damping device 50 includes tube 70 having damping
portion 72, lift portion 74, a second linear portion, shown as
damping portion 76, and a section extending between flow device 60
and the second end of damping portion 72, shown as lift portion 78.
In some embodiments, flow device 60 flows a fluid through a fluid
flow path defined by lift portion 74, damping portion 72, lift
portion 78, and damping portion 76. Such a fluid flow may occur in
the direction described (i.e. first upwards through lift portion
74) or in a reverse direction (i.e. first through damping portion
76). In some embodiments, the fluid is initially located within
tube 70. Such a configuration may allow a portion of tube 70 to
also serve as part of a fire suppression system of building 30
(e.g., tube 70 may include various outlets for sprinklers, etc.).
In other embodiments, the flow device initially receives water from
a fluid source and thereafter flow the fluid through tube 70.
[0032] According to an exemplary embodiment, fluid damping device
50 having lift portion 74, damping portion 72, lift portion 78, and
damping portion 76 reduces the oscillations of building 30. As
shown in FIGS. 4-5, damping portion 72 is coupled to super
structure 80. According to the exemplary embodiment shown in FIG.
5, a fluid flowing from lift portion 74 to lift portion 78 through
damping portion 72 imparts a damping force on super structure 80.
In some embodiments, lift portion 78 is coupled to damping portion
72 with a coupler (e.g., bend, elbow, etc.). A fluid flowing
through the coupler and changing directions (e.g., from a direction
along damping portion 72 to a direction along lift portion 78) also
imparts a damping force on super structure 80.
[0033] For an incompressible fluid and a constant area damping
portion, a portion of the damping force is related to the product
of the flow rate, fluid density, and change in velocity of the
flowing fluid. Various factors impact the change in velocity of the
flowing fluid including, among others, the surface roughness of the
interior wall of damping portion 72 or the presence of paddles or
interference members within damping portion 72. According to an
exemplary embodiment, damping portion 72 includes an interior
surface roughness designed to inhibit fluid flow (e.g., cast iron
or another material and include an absolute roughness of 260
microns, concrete having a surface roughness of between 0.3 and 3
millimeters, etc.). In other embodiments, damping portion 72
includes at least one of an orifice and a flange to increase the
change in velocity across damping portion 72.
[0034] While fluid flowing through damping portion 72 provides a
damping force in a first direction, the fluid also provides a
damping force in the opposite direction as it flows through damping
portion 76. According to an exemplary embodiment, such a damping
force is incorporated as part of a fluid damping strategy of fluid
damping device 50. In other embodiments, the fluid damping strategy
reduces damping forces due to fluid flowing through damping portion
76. Such a reduction may occur by reducing the surface roughness of
the interior wall of damping portion 76, coupling damping portion
76 to a ground volume, or coupling damping portion 76 to building
30 with isolators (e.g., resilient members, dampers, etc.), among
other alternatives.
[0035] Referring still to the exemplary embodiments shown in FIGS.
2-5, the damping portions are located in a plane orthogonal to a
central axis of building 30 and extend laterally across a length of
building 30. Such damping sections may include ends positioned at
the same vertical location along building 30. In other embodiments,
the damping sections are located in another plane that is not
orthogonal to the central axis of building 30, include ends
positioned at different vertical locations along building 30, or do
not extend laterally across a length of building 30 (i.e. the
damping portions are angled within various planes).
[0036] Referring next to the exemplary embodiment shown in FIG. 6,
fluid damping device 50 includes flow device 60 and tube 70 having
lift portion 74, lift portion 78, and a non-linear (i.e.
curvilinear) portion, shown as non-linear damping portion 77. As
noted above, fluid damping device 50 may provide damping forces to
building 30 during an oscillation event. In some embodiments,
non-linear damping portion 77 includes ends located along the same
side of building 30. In other embodiments, tube 70 does not include
lift portion 78 and non-linear damping portion 77 includes an end
cap. In still other embodiments, non-linear damping portion 77
includes still other shapes. As shown in FIG. 6, non-linear damping
portion 77 partially surrounds a central axis of building 30, and a
fluid flowing through non-linear damping portion 77 applies a
damping torque on super structure 80. From the foregoing, it should
be understood that various shapes and configurations of pipes may
be oriented to provide damping forces in various directions.
[0037] According to the exemplary embodiment shown in FIG. 7, a
structure, shown as building 100 includes a base portion 102. As
shown in FIG. 7, base portion 102 is coupled to a ground volume
having a ground surface 104. According to an exemplary embodiment,
building 100 includes an elevated portion 106. In some embodiments,
building 100 includes a structural frame, a portion of which is
shown as super structure 108.
[0038] As shown in FIG. 7, building 100 includes a damping device,
shown as fluid damping device 110 positioned within elevated
portion 106 and coupled to super structure 108. According to the
exemplary embodiment shown in FIG. 7, building 100 includes fluid
damping device 110 positioned at height "h" above ground surface
104. In other embodiments, building 100 includes a plurality of
fluid damping devices 110 positioned at different elevations from
ground surface 104.
[0039] Referring still to the exemplary embodiment shown in FIG. 7,
fluid damping device 110 includes a first fluid storage device,
shown as tank 112, and a second fluid storage device, shown as tank
114. Tank 112 and tank 114 may include several components arranged
into a shell, the shell defining an inner volume and a fluid
orifice. While shown in FIG. 7 as having a rectangular shape, tank
112 and tank 114 may have other suitable shapes (e.g., ovular,
cylindrical, etc.). According to an exemplary embodiment, tank 112
and tank 114 are coupled to super structure 108 (e.g., with
welding, a bolted connection, an adhesive, etc.). In some
embodiments, forces applied to the inner surfaces of tank 112 and
tank 114 are transferred to a portion of building 100 through super
structure 108.
[0040] As shown in FIG. 7, tank 112 and tank 114 are positioned on
opposing lateral sides of building 100. In other embodiments, tank
112 and tank 114 are located along the same lateral side of
building 100. In still other embodiments, at least one of tank 112
and tank 114 are positioned along a centerline of building 100.
According to an exemplary embodiment, tank 112 and tank 114 are
positioned at the midpoint of each opposing side. Tank 112 and tank
114 may be positioned at ends of each opposing side (i.e. in
opposing corners, etc.) or in still other positions. It should be
understood from the foregoing that tanks 112 and 114 may be
positioned in various positions of building 100.
[0041] As shown in FIG. 7, fluid damping device 110 includes a flow
device 116 coupled to super structure 108 and disposed between tank
112 and tank 114. Such a position of flow device 116 may provide
various advantages. By way of example, positioning flow device 116
between tank 112 and tank 114 reduces a delay (i.e. the time needed
to deliver a fluid to tank 112 or tank 114), thereby improving a
response time of fluid damping device 110.
[0042] Referring still to the exemplary embodiment shown in FIG. 7,
fluid damping device 110 includes a first tube, shown as tube 118,
and a second tube, shown as tube 119. As shown in FIG. 7, tube 118
extends between flow device 116 and tank 112, and tube 119 extends
between flow device 116 and tank 114. Tube 118 and tube 119 may
include ends disposed over the orifices of tank 112 and tank 114,
respectively. Tube 118 and tube 119 may also include second ends,
the second ends engaging a plurality of fluid ports defined by flow
device 116. In some embodiments, tube 118 and tube 119 facilitate
fluid communication between flow device 116, tank 112, and tank
114.
[0043] According to an exemplary embodiment, a fluid is disposed
within the inner volume at least one of tank 112 and tank 114.
According to an alternative embodiment, fluid damping device 110
includes an inlet pipe to couple flow device 116 with a fluid
supply (e.g., retaining pond, container, etc.). Because of the
fluid communication between flow device 116, tank 112, and tank
114, a fluid may be repositioned by flow device 116 into tank 112,
into tank 114, emptied from both tank 112 and tank 114, or
otherwise delivered through fluid damping device 110. According to
an exemplary embodiment, the fluid is initially positioned within
tank 112 (serving as the fluid supply), and flow device 116
delivers the fluid from tank 112 into tank 114. According to an
alternative embodiment, the fluid is initially positioned within
tank 114, and flow device 116 delivers the fluid from tank 114 into
tank 112. It should also be understood that flow device 116 may
selectively flow a fluid from a fluid supply into at least one of
tank 112 and tank 114. Fluid damping device 110 may utilize the
motion of the fluid flowing into tank 112 or tank 114 to provide a
damping force to building 100 through super structure 108.
[0044] According to an alternative embodiment, fluid damping device
110 includes various fluid storage devices located in at least one
of different elevations along elevated portion 106 and in different
lateral positions relative to super structure 108. Such devices may
include additional components (e.g., directional flow valves, check
valves, etc.) to facilitate flow between the fluid storage devices.
By way of example, fluid damping device 110 may include four fluid
storage devices arranged as a first set positioned at a first
elevation and a second set positioned at a second elevation. At
least one flow device may deliver a fluid between the four fluid
storage devices. The pairs of fluid storage devices may be
positioned such that fluid flow between the first set of fluid
storage devices provides a damping force along a first direction
and fluid flow between the second set of fluid storage devices
provides a damping force along a second direction. In some
embodiments, the first direction is perpendicular to the second
direction. Still other arrangements of fluid storage devices and
piping may be provided to provide damping forces in still other
directions, according to various alternative embodiments.
[0045] Referring next to the exemplary embodiment shown in FIG. 8,
a structure, shown as building 140, includes a damping device,
shown as fluid damping device 150. According to an exemplary
embodiment, fluid damping device 150 provides damping forces to
building 140 during an oscillation event. As shown in FIG. 8, fluid
damping device 150 includes a flow device, shown as flow device
152. In some embodiments, flow device 152 delivers fluid from a
fluid supply into other portions of fluid damping device 150.
According to an exemplary embodiment, fluid damping device 150
includes a fluid inlet, shown as inlet tube 154, to couple flow
device 152 with the fluid supply. As shown in FIG. 8, flow device
152 is coupled to building 140 at the elevation of a ground
interface 142. In other embodiments, flow device 152 is coupled to
building 140 at another elevation or positioned outside building
140, among other alternative configurations.
[0046] According to the exemplary embodiment shown in FIG. 8, fluid
damping device 150 includes an elevating portion, shown as lift
pipe 156. As shown in FIG. 8, lift pipe 156 includes a first end
coupled to flow device 152 and an extended portion projecting
upward along a first side of building 140. In other alternative
embodiments, lift pipe 156 is positioned along a central portion of
building 140.
[0047] As shown in FIG. 8, fluid damping device 150 includes a
first subsystem, shown as first damping branch 160, and a second
subsystem, shown as second damping branch 170. In some embodiments,
building 140 defines an outer surface that interfaces with an
exterior environment (e.g., surrounding air, surrounding water,
etc.). According to an exemplary embodiment, the outer surface of
building 140 defines a plurality of outlets to facilitate a fluid
flow from an inner volume of building 140 to an exterior
environment. As shown in FIG. 8, first damping branch 160 includes
a plurality of fluid outlets, shown as nozzles 162, coupled along
an outer surface of building 140. In some embodiments, nozzles 162
provide a fluid flow through the outlets of building 140.
[0048] Referring still to the exemplary embodiment shown in FIG. 8,
first damping branch 160 includes a plurality of tubes (i.e.
connection pipes), shown as coupling tubes 164, extending between
nozzles 162 and a tube, shown as manifold tube 166. In some
embodiments, second damping branch 170 includes a plurality of
nozzles 172 coupled to manifold tube 176 with coupling tubes 174.
As shown in FIG. 8, manifold tube 166 and manifold tube 176 each
include an end coupled to lift pipe 156. Such a configuration is
intended to couple nozzles 162 and nozzles 172 in fluid
communication with flow device 152. In various alternative
embodiments, other arrangements of pipes may couple nozzles 162 and
nozzles 172 in fluid communication with flow device 152 (e.g., more
or fewer lift pipes, fewer nozzles per damping branch, etc.).
[0049] Lift pipe 156, first damping branch 160, and second damping
branch 170 define a plurality of flow paths between flow device
152, nozzles 162, and nozzles 172. According to an exemplary
embodiment, flow device 152 delivers a fluid through lift pipe 156
and out of at least one of nozzles 162 and nozzles 172. In some
embodiments, fluid is provided to nozzles 162 and nozzles 172 when
flow device 152 is engaged (e.g., during an oscillation event). In
other embodiments, fluid damping device 150 includes a valve to
selectively deliver the fluid through nozzles 162 and nozzles 172
when flow device 152 is engaged. A controller selectively actuates
the valve between a first position and a second position as part of
a control scheme. In other embodiments, the valve is manually
operable.
[0050] In still other embodiments, fluid damping device 150
includes a plurality of valves (e.g., a valve associated with each
damping branch, a valve associated with each nozzle, etc.). In some
embodiments, flow device 152 pressurizes the fluid (e.g., within a
container, within lift pipe 156 and the damping branches, etc.).
Upon actuation of the valves, the pressurized fluid is released
through at least one nozzle. In some embodiments, flow device 152
continues to provide a fluid flow to the nozzles upon actuation of
the valve such that the fluid flow from the nozzles is continuous.
In other embodiments, flow device 152 pressurizes the fluid and
thereafter disengages such that the fluid is directed from the
nozzles in discrete amounts rather than as a continuous flow.
[0051] Referring still to the exemplary embodiment shown in FIG. 8,
nozzles 162 and nozzles 172 direct a fluid into an exterior
environment. According to an exemplary embodiment, nozzles 162 and
nozzles 172 include housings having a cross sectional area that
decreases in area such that the velocity of the fluid is increased
as the fluid travels therethrough. It should be understood that
such fluid is directed from building 140 with a force that is
related to the diameter of the pipes, the flow rate, and the
dimensions of the nozzle. In some embodiments, at least a portion
of fluid damping device 150 is coupled to a frame member of
building 140 to provide damping forces (e.g., reaction forces from
nozzles 162 and nozzles 172) to building 140.
[0052] According to an exemplary embodiment, nozzles 162 and
nozzles 172 each include a central axis. In some embodiments, the
central axes of nozzles 162 and 172 are perpendicular to a central
axis of building 140 (i.e. orthogonal to an outer surface of
building 140). In other embodiments, at least a portion of the
nozzles are arranged such that the central axes are angularly
offset from an outer surface of building 140 to, by way of example,
direct the fluid flow downward, upward, or to a side of building
140. In still other embodiments, fluid damping device 150 includes
at least one moveable nozzle (i.e. a nozzle not having a fixed
orientation relative to a structural frame of building 140 to
provide variable damping forces). Regardless of orientation, fluid
damping device 150 imparts damping forces from nozzles 162 and
nozzles 172 to building 140 along an axis opposite the direction of
fluid flow.
[0053] As shown in FIG. 8, nozzles 162 and nozzles 172 form a
nozzle array along a face of building 140. While shown in FIG. 8 as
positioned along a face of building 140, it should be understood
that outlets may be defined along a single surface, along a
plurality of surfaces, or along still other features of building
140. By way of example, building 140 may define two opposing
outlets along a lateral direction and two opposing outlets along a
longitudinal direction such that corresponding nozzles provide
damping forces in various directions. As shown in FIG. 8, nozzles
162 and 172 form a two by three array. In various alternative
embodiments, fluid damping device 150 includes nozzles arranged in
a one dimensional array or includes nozzles arranged irregularly.
In various alternative embodiments, a tube (e.g., coupling tube
164, coupling tube 174, etc.) may terminate into multiple nearby
nozzles (e.g., nozzles 162, nozzles 172, etc.). Such nearby nozzles
may be oriented in the same direction or oriented in different
directions (e.g., perpendicular to each other). A valve may be used
to control which of the nozzles is used to eject the fluid, and
hence control the direction of the imparted damping force.
[0054] It should be understood that the damping device described
herein may include any combination of flow devices, pipes, tanks,
nozzles, or other components to provide damping forces during an
oscillation event. Specifically, combinations of flow devices,
pipes, tanks, nozzles, or other components may be incorporated in a
configuration particularly suited for a structure. In some
embodiments, the locations and orientations of the nozzles are
selected based on knowledge of a selected natural vibrational mode
of the structure (e.g., at sites of maximum modal deflection). The
selected natural mode may be one whose modal frequency is similar
to a potential seismic excitation frequency. The selected natural
mode may be chosen based on numerical calculations of oscillations
of the structure in response to anticipated seismic excitations. In
some embodiments, the damping device includes specific components
tailored for a particular loading condition (e.g., sharp seismic
loading, dull or rolling seismic loading, wind loading, etc.) of a
structure. By way of example, the damping device may include a
fluid storage device positioned in an elevated location and a flow
device that delivers a fluid from the fluid storage device out from
a nozzle. Such a configuration may reduce the response time (i.e.
the time between engaging the flow device and the structure
experiencing damping forces), and such a reduction may be
particularly relevant for sharp seismic loading capable of
producing short duration yet large magnitude oscillations. In some
embodiments, multiple flow devices are provided and situated at
various locations within the damping device.
[0055] Referring next to the exemplary embodiment shown in FIGS.
9-10, a damping device, shown as fluid damping device 210, alters
the natural vibration mode of a structure, shown as building 200.
In some embodiments, altering the natural vibration mode of
building 200 reduces the vibratory energy within building 200
during an oscillation event. As shown in FIG. 9, fluid damping
device 210 includes a fluid flow device, shown as flow device 212,
a first pipe, shown as tube 214, and a second pipe, shown as tube
216. According to an exemplary embodiment, tube 214 and tube 216
each include a first end coupled to flow device 212. In some
embodiments, a second end of tube 214 interfaces with a fluid
supply (e.g., a container, a retaining pond, etc.).
[0056] According to the exemplary embodiment shown in FIG. 9, a
second end of tube 216 is coupled to a first fluid storage device,
shown as tank 220. Tank 220 defines an inner storage volume that
store a fluid, according to an exemplary embodiment. As shown in
FIG. 9, tank 220 is coupled to a structural frame of building 200,
a portion of which is shown as super structure 202 in an elevated
position relative to a ground surface 204. As shown in FIG. 9, tube
214, flow device 212, and tube 216 define a flow path. According to
an exemplary embodiment, flow device 212 delivers a fluid from tube
214 to tank 220 through tube 216. According to an alternative
embodiment, flow device 212 delivers a fluid from tank 220 through
tube 216 and tube 214 (i.e. flow device 212 delivers a fluid in
either direction along the flow path). In other embodiments, flow
device 212 selectively receives a fluid from tube 214, pressurizes
the fluid, and thereafter provides the fluid to tank 220 through
tube 216. Such a fluid damping device 210 may also include valves
or other flow control devices to facilitate such operation. Valves
may be actuated manually or by a controller as part of a fluid
damping control scheme.
[0057] According to an exemplary embodiment, fluid damping device
210 delivers a fluid into tank 220 during an oscillation event to
change the natural vibration mode of building 200. It should be
understood that the natural vibration mode of structures may vary
based on, among other factors, the materials used to build the
structure, the design of the structure (i.e. the arrangement of
structural components), and the distribution of weight within the
structure. The weight of the fluid delivered into tank 220 may vary
the distribution of weight within building 200 thereby altering the
natural vibration mode and the frequency response of building 200
during an oscillation event. According to an alternative
embodiment, fluid is delivered from a fluid storage device to alter
the natural vibration mode of building 200, changing the mode's
frequency and/or spatial shape.
[0058] According to the alternative embodiment shown in FIG. 10,
fluid damping device 210 includes tank 220 and a second fluid
storage device, shown as tank 222. In some embodiments, tank 222 is
coupled to flow device 212 with tube 216 and super structure 202.
As shown in FIG. 10, tank 220 is positioned at a first elevation of
building 200 and tank 222 is positioned at a second, lower
elevation of building 200. Such a configuration may allow flow
device 212 to deliver a fluid into at least one of tank 220 and
tank 222, the different positions of tank 220 and tank 222 allowing
for fluid damping device 210 to variably alter the natural
vibration mode of building 200. In some embodiments, valves are
positioned within the flow path to selectively allow a fluid flow
to or from at least one of tank 220 and tank 222. According to an
alternative embodiment, a fluid damping device includes multiple
flow devices, more or fewer fluid storage devices, or the fluid
storage devices are otherwise positioned.
[0059] According to still another alternative embodiment shown in
FIG. 11, flow device 212 of fluid damping device 210 is coupled to
building 200 in an elevated position. As shown in FIG. 11, flow
device 212 is positioned within building 200 between tank 220 and
tank 222. Such an elevated position of flow device 212 may reduce a
response time of fluid damping device 210, reduce the need for
additional piping, or provide still other benefits. According to an
exemplary embodiment, pipes, shown as tubes 218, couple tank 220
and tank 222 to flow device 212. According to an exemplary
embodiment, a fluid is disposed within at least one of tank 220 and
tank 222, and flow device 212 delivers the fluid from at least one
of tank 220 and tank 222 (e.g., from one fluid storage device into
the other fluid storage device) during an oscillation event to
change the natural frequency mode of building 200. In some
embodiments, fluid damping device 210 includes a pipe coupling flow
device 212 with a fluid supply (e.g., container, retaining pond,
etc.) to, by way of example, facilitate the initial filling of tank
220 or tank 222, facilitate the emptying of tank 220 or tank 222,
or otherwise engage with other components of fluid damping device
210 as part of a damping control scheme.
[0060] According to an exemplary embodiment, a fluid damping device
includes a controller and a fluid flow device. The controller
interfaces with the fluid flow device. The controller may send or
receive command signals to engage or disengage the fluid flow
device, change the direction of the fluid flow from the fluid flow
device, or change the rate that the fluid is discharged from the
fluid flow device, among other alternatives. In some embodiments,
the controller sends a command signal after receiving an event
signal indicating an oscillation event. By way of example, a sensor
(e.g., geophone, accelerometer) that detects seismic activity,
acceleration, structural stress or strain, structural deflection,
fluid mass, volume, or forces, or another phenomena may send the
event signal. In some embodiments, the sensor is coupled to a
portion of the structure (e.g., the top of a building, a middle
point of a bridge, other suitable locations, etc.). In some
embodiments, accelerations can be measured along multiple
directions, or in different sites. Differential accelerations
between different directions or locations may be used to measure
modal excitations. Structural deflections may be derived (e.g.,
from double integration of accelerations) or directly measured
relative to external references (e.g., with a global positioning
system, a differential global positioning system, interferometers,
or other metrology tools), according to various alternative
embodiments. In other embodiments, the sensor interacts remotely
with a fluid damping device (e.g., sensors positioned at
established geographic seismology facilities, etc.).
[0061] According to an exemplary embodiment, the controller
includes a module coupled to the sensor, and the sensor provides a
sensor signal to the module. Such a module processes the sensor
signal and determines whether an oscillation event may occur, is
occurring, or has occurred. In some embodiments, the module
includes various parameters (e.g., a threshold acceleration or
displacement, etc.), the parameters allowing the module to identify
an oscillation event and provide an event signal. According to an
exemplary embodiment, the module provides the event signal to the
controller, which provides a command signal to a component of the
fluid damping device.
[0062] According to an exemplary embodiment, the controller
includes a processing circuit to implement a control strategy that
damps oscillations within a structure. In some embodiments, the
control strategy is computed in real-time based on numerical
simulations of the oscillation. In other embodiments, the control
strategy is selected from one or more pre-derived control
strategies. During an oscillation event, such as an earthquake, a
building may sway significantly. Failure to implement a control
strategy may impart excessive stresses within the structure. Such
excessive stresses may allow a building to experience the first,
second, or third failure modes.
[0063] In some embodiments, the controller implements a control
strategy that incorporates several damping techniques. It should be
understood that some earthquakes exhibit loading that provides the
largest displacement within the first minute and the largest peak
loading within the first half of the seismic event. According to an
exemplary embodiment, a sensor coupled to a building senses at
least one of a building oscillation and a building displacement. In
some embodiments, a controller interprets the sensor data,
determines whether the data indicates an oscillation event based on
a threshold acceleration (e.g., 1.0 meters per second squared) or a
threshold displacement (e.g., 0.5 meters), and interfaces with a
fluid damping device (e.g., turn on a fluid flow device, engage a
valve to facilitate fluid flow, etc.) to provide damping forces. In
other embodiments, the controller engages the damping device to
apply predetermined damping forces after receiving various features
describing an oscillation event (e.g., location, magnitude, and
starting time of an earthquake).
[0064] According to an exemplary embodiment, the fluid damping
device provides damping forces to particular locations of the
building. The distribution of damping forces may be related to the
loading imparted during the oscillation event. By way of example,
the upper portion of a building experiencing large loading due to
wind may sway more than other portions, and a damping force applied
to an elevated position of the building may reduce at least one of
the displacement and acceleration of the building. According to an
exemplary embodiment, the controller operates with an initial
damping strategy of applying a single damping force, a plurality of
damping forces concurrently, or a plurality of damping forces in a
pattern designed to damp structure oscillations (e.g., apply a
force to different portions of the building, apply a damping force
first using damping pipes or nozzles and then using tanks, etc.),
among other potential initial damping strategies.
[0065] In some embodiments, the fluid damping device provides only
an initial damping force. According to an exemplary embodiment, the
fluid damping device provides an initial damping force or changes
the natural building mode, monitors a response by the structure,
and provides additional damping forces or again change the natural
building mode. The fluid damping device may continue this iterative
process until a condition is satisfied (e.g., the building no
longer experiences loading from the oscillation event, the building
no longer accelerates or is displaced, etc.).
[0066] As described above, a fluid damping device generates a
damping force by delivering a fluid at least one of through a
damping pipe, into a fluid storage device, and through a nozzle. In
some embodiments, the fluid damping device interfaces with still
other damping devices (e.g., passive dampers, fluid viscous
dampers, etc.) to operate as part of a coordinated damping system.
According to an exemplary embodiment, the building includes a fluid
damping system capable of providing damping forces in various
directions to, by way of example, reduce oscillations due to
loading in various directions.
[0067] Additional vibratory energy may be imparted into the
structure where loading during an oscillation event excites a
natural vibration mode of the structure. A fluid damping device
damps the additional vibratory energy that may otherwise damage the
structure. According to an exemplary embodiment, the fluid damping
device changes the natural vibration mode of the structure to a
mode that is offset (e.g., out of phase with, having a different
phase angle, etc.) from the frequency of the loading. Such a change
in the vibration mode may be effective in various conditions (e.g.,
where the input from the oscillation event is in a narrow frequency
band).
[0068] According to an exemplary embodiment, the controller first
reduces oscillation due to loading by applying a damping force and
thereafter engages a fluid flow device to deliver a fluid (e.g.,
into or from a fluid storage device) to change the natural
vibration mode of the structure. According to an alternative
embodiment, the controller interfaces with the damping device to
provide only damping forces, only change the natural vibration
mode, first change the natural vibration mode and thereafter apply
damping forces, or employ still another strategy. While an
illustrative control strategy has been described, it should be
understood that a fluid damping device may include a particular
control strategy for a specific structure. Further, fluid damping
devices may be employed in buildings, bridges, or other structures
to damp loading due to earthquakes, wind, or other inputs. Such
buildings, bridges, or other structures may be affixed to a ground
surface (e.g., directly coupled, coupled with pylons, coupled with
hydraulic or polymeric isolators, etc.).
[0069] It is important to note that the construction and
arrangement of the elements of the systems and methods as shown in
the exemplary embodiments are illustrative only. Although only a
few embodiments of the present disclosure have been described in
detail, those skilled in the art who review this disclosure will
readily appreciate that many modifications are possible (e.g.,
variations in sizes, dimensions, structures, shapes and proportions
of the various elements, values of parameters, mounting
arrangements, use of materials, colors, orientations, etc.) without
materially departing from the novel teachings and advantages of the
subject matter recited. For example, elements shown as integrally
formed may be constructed of multiple parts or elements. It should
be noted that the elements and/or assemblies of the enclosure may
be constructed from any of a wide variety of materials that provide
sufficient strength or durability, in any of a wide variety of
colors, textures, and combinations. Additionally, in the subject
description, the word "exemplary" is used to mean serving as an
example, instance or illustration. Any embodiment or design
described herein as "exemplary" is not necessarily to be construed
as preferred or advantageous over other embodiments or designs.
Rather, use of the word exemplary is intended to present concepts
in a concrete manner. Accordingly, all such modifications are
intended to be included within the scope of the present inventions.
The order or sequence of any process or method steps may be varied
or re-sequenced according to alternative embodiments. Any
means-plus-function clause is intended to cover the structures
described herein as performing the recited function and not only
structural equivalents but also equivalent structures. Other
substitutions, modifications, changes, and omissions may be made in
the design, operating conditions, and arrangement of the preferred
and other exemplary embodiments without departing from scope of the
present disclosure or from the spirit of the appended claims.
[0070] The present disclosure contemplates methods, systems and
program products on any machine-readable media for accomplishing
various operations. The embodiments of the present disclosure may
be implemented using existing computer processors, or by a special
purpose computer processor for an appropriate system, incorporated
for this or another purpose, or by a hardwired system. Embodiments
within the scope of the present disclosure include program products
comprising machine-readable media for carrying or having
machine-executable instructions or data structures stored thereon.
Such machine-readable media can be any available media that can be
accessed by a general purpose or special purpose computer or other
machine with a processor. By way of example, such machine-readable
media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical
disk storage, magnetic disk storage or other magnetic storage
devices, or any other medium which can be used to carry or store
desired program code in the form of machine-executable instructions
or data structures and which can be accessed by a general purpose
or special purpose computer or other machine with a processor. When
information is transferred or provided over a network or another
communications connection (either hardwired, wireless, or a
combination of hardwired or wireless) to a machine, the machine
properly views the connection as a machine-readable medium. Thus,
any such connection is properly termed a machine-readable medium.
Combinations of the above are also included within the scope of
machine-readable media. Machine-executable instructions include,
for example, instructions and data, which cause a general purpose
computer, special purpose computer, or special purpose processing
machines to perform a certain function or group of functions.
[0071] Although the figures may show a specific order of method
steps, the order of the steps may differ from what is depicted.
Also, two or more steps may be performed concurrently or with
partial concurrence. Such variation will depend on the software and
hardware systems chosen and on designer choice. All such variations
are within the scope of the disclosure. Likewise, software
implementations could be accomplished with standard programming
techniques with rule based logic and other logic to accomplish the
various connection steps, processing steps, comparison steps and
decision steps.
* * * * *