OCEN 201 Introduction to Ocean

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OCEN 201Introduction to Ocean Coastal
Engineering

• Instruments Measurements
• Jun Zhang
• Jun-zhang_at_tamu.edu

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• Measurements   (Laboratory Field)
• Laboratory Measurements
• Under well-controlled conditions or environments
  , they are easier to be conducted than the
  corresponding Field Measurements.
• They are cheaper and more accurate.
• In view of coastal and ocean engineering, the
  sizes of the models used in laboratory
  measurements are much smaller than those of their
  prototypes. Hence, essential similarity laws must
  be followed.
• It is not likely to follow all essential
  similarity laws in model tests, certain
  assumptions must be made. Therefore, Laboratory
  Measurements cannot totally replace the related
  Field Measurements.   

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• Field Measurements
• They are difficult to be conducted because of
  harsh environments (e.g. rough seas and high wind
  speed in a hurricane).
• They are usually very expensive and may not be
  accurate.
• It is necessary to conduct Field Measurements in
  order to examine the validity of the assumptions
  (such as the neglect of certain similarity laws)
  made in the related Laboratory Measurements.
    

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• Similarity Laws (Chapter 9)
• Geometric Similarity (model and prototype are
  geometrically similar) that is, the
  corresponding ratios of their dimensions are the
  same.
• Kinematic Similarity
• Dynamic Similarity. (matching non-dimensional
  coeff. between model prototype)
• Important non-dimensional coefficients
• - Reynolds (viscous)
• - Froude (gravity)
• - Euler (pressure)
• - Mach (compressibility or
  elasticity)
• - Weber (surface tension)
• Table 10-3 PP354 (old version pp267)   

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• Measurements   Intstruments 
• Survey water depth beach contour (Lidar, sonar
  traditional survey instruments)
• Force or pressure (strain gage, load cell
  pressure transducer)
• Wave elevation (wave gage, indirect
  measurements pressure transducer, velocimetry,
  LDV, ADV PIV)
• Velocity (LDV, ADV PIV, electro-magnetic meter)
• Accelerations Accelerometer

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• Measurements   Intstruments  (continue)
• 5. Movement or deformation (optical tracking
  system, PIV)
• Wind velocity
• Temperature
• Salinity
• Density
• Sea Gilder

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Wave Gage (Capacity Resistance)

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Directional Wave Gages
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Principles of Strain Gages
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Pressure Transducers
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For the information about LDV PIV and Their
Applications see the supplement materials
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• Facilities for Ocean Coastal Related Lab M.
• Wave Basins (Deepwater Shallow water Basin
  OTRC wave Basin Hayens Coastal Lab Basin)
• -Directional wave generation
• - Current generation (Nozzle type)
• - Wind generation
• 2. Wave Flume (1-D wave Basin, CLAB 109,)
• - Unidirectional wave generation
• - Current generation
• - Wind generation

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• Facilities for Ocean Coastal Related Lab M.
• Dredging loop (Hynes coastal lab)
• - Current generation
• - Towing Carriage

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Description
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Overview

• AUV / UUV
• Self-regulated buoyancy
• Propelled by battery power
• Propelled by oceans thermal energy
• New technology!

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History

• Preliminary designs (1986)
• Test runs Florida, New York (1991)
• Result the Slocum glider
• Scripps / Woods Hole Spray
• APL-UW Seaglider
• Slocum Thermal Glider (2005)

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Vehicle Control

• Driving force lift provided by wings
• Pitch/roll internal weight shift
• Onboard computers
• Surface GPS fixes
• Pressure sensors
• Tilt sensors
• Magnetic compasses

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Slocum, Spray, and Seaglider
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Webb Research Slocum

• Weight 52 kg
• Diameter 21.3 cm
• Length 1.5 m
• Speed 40 cm/s
• Depth 4 200 m
• Endurance 30 days
• Range 1500 km
• Alkaline batteries

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Webb Research Slocum
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Webbs Thermal Glider

• Weight 60 kg
• Diameter 21.3 cm
• Length 1.5 m
• Speed 40 cm/s
• Depth 4 2000 m
• Endurance 5 years!
• Range 40000 km
• Environmental power

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Webbs Thermal Glider
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Scripps/Woods Hole Spray

• Weight 52 kg
• Diameter 20 cm
• Length 2 m
• Speed 25 cm/s
• Depth 1500 m
• Endurance 815 cycles
• Range 4700 km
• Lithium cells

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Scripps/Woods Hole Spray
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APL-UW Seaglider

• Weight 52 kg
• Diameter 30 cm
• Length 1.8 m
• Speed 25 cm/s
• Depth 1000 m
• Endurance 650 cycles
• Range 4600 km
• Lithium cells

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APL-UW Seaglider
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Design
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Early Field Trials

• Wakulla Springs, Florida
• Straight flight, dives, turns
• Navigation and data relays
• Telemetry recorded
• Maneuvering parameters
• Instabilities found

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Test Dive Profile
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Design Solutions

• Increase glide speed
• Decrease pitch/heading oscillations
• Increase stall resistance
• Revise autopilot algorithms
• Swept wings
• Antenna moved to nose

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Test Results, Conclusions

• Glide slope ratio similar to Space Shuttle
• Energy expended at bottom of dive cycle
• Decrease dive cycles less energy
• How do we decrease cycles?
• Lower glide speeds
• Longer endurance
• Greater range

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Applications
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Current Uses

• Slocum shallow water, short range
• Spray/Seaglider deeper, longer dives
• Take measurements
• -temperature
• -conductivity (salinity)
• -currents
• -chlorophyll fluorescence
• -optical backscatter

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Current Uses

• Seaglider
• -physical, chemical oceanography
• -tactical oceanography
• -underwater Reconnaissance
• -communications gateway
• -navigation aid

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Dive Profile
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Dive Profile
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Spray La Jolla 2001

• Underwater canyon, 3 km width
• 11 day mission
• Maintained synthetic mooring
• Plotted wave, current propagation

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Monterey 2003

• 10 Slocums and 5 Sprays
• Sample 100 square-km area
• Use networking to forecast conditions
• Example of large-scale team usage

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Monterey 2003
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Spray Gulf Stream 2004

• New England to Bermuda
• First crossing of the Gulf Stream

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Seaglider TASWEX-04

• Navy ASW exercise, East China Sea
• Battlespace assessment
• Tactical remote sensing
• Mission successful

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Future Uses

• ONR Liberdade XRay
• USN PLUSNet program
• Largest glider
• Hydrodynamic efficiency
• Acoustics, electric field sensors
• 1-3 kt cruise, 1200-1500 km range

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Liberdade XRay
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Economics