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Applied Underwater Acoustics - Leif Bj?rn?
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Applied Underwater Acoustics - Leif Bj?rn?
von: Thomas Neighbors, David Bradley
Elsevier Reference Monographs, 2017
ISBN: 9780128112472
982 Seiten, Download: 173640 KB
 
Format: EPUB, PDF
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Inhaltsverzeichnis

  Applied Underwater Acoustics 2  
  Applied Underwater Acoustics 4  
  Copyright 5  
  Dedication 6  
  Contents 8  
  List of Contributors 14  
  Preface 16  
  1 - General Characteristics of the Underwater Environment 18  
     1.1 INTRODUCTION 18  
     1.2 A BRIEF EXPOSITION OF THE HISTORY OF UNDERWATER ACOUSTICS 22  
        1.2.1 UNDERWATER ACOUSTICS BEFORE 1912 23  
        1.2.2 THE YEARS 1912 THROUGH 1918 25  
        1.2.3 THE YEARS 1919 THROUGH 1939 27  
        1.2.4 THE YEARS 1940 THROUGH 1946 29  
        1.2.5 THE YEARS AFTER 1946 29  
     1.3 INTERNATIONAL STANDARD UNITS 32  
     1.4 THE DECIBEL SCALES 33  
     1.5 FEATURES OF OCEANOGRAPHY 35  
        1.5.1 SOUND SPEED PROFILES 35  
        1.5.2 THERMOCLINES 39  
        1.5.3 ARCTIC REGIONS 41  
        1.5.4 DEEP ISOTHERMAL LAYERS 46  
        1.5.5 EXPRESSIONS FOR THE SPEED OF SOUND 50  
        1.5.6 SURFACE WAVES 53  
        1.5.7 INTERNAL WAVES 60  
        1.5.8 BUBBLES FROM WAVE BREAKING 63  
        1.5.9 OCEAN ACIDIFICATION 74  
        1.5.10 DEEP-OCEAN HYDROTHERMAL FLOWS 77  
        1.5.11 EDDIES, FRONTS, AND LARGE-SCALE TURBULENCE 80  
        1.5.12 DIURNAL AND SEASONAL CHANGES 82  
     1.6 SONAR EQUATIONS 83  
        1.6.1 DEFINITIONS OF THE SONAR EQUATION TERMS 84  
        1.6.2 SONAR EQUATIONS 88  
     1.7 ABBREVIATIONS 92  
     Acknowledgment 93  
     REFERENCES 93  
  2 - Sound Propagation 102  
     2.1 THE CONCEPT OF WAVES 102  
        2.1.1 THE WAVE EQUATION FOR AN INVISCID FLUID 103  
        2.1.2 THE HELMHOLTZ EQUATION 106  
        2.1.3 HARMONIC WAVES 108  
        2.1.4 PLANE WAVES 110  
        2.1.5 CYLINDRICAL WAVES 115  
        2.1.6 SPHERICAL WAVES 119  
        2.1.7 PLANE WAVE DECOMPOSITION OF A SPHERICAL WAVE 122  
     2.2 SOUND PROPAGATION IN A VISCOUS FLUID 124  
        2.2.1 DISPERSION FORMULAS 125  
        2.2.2 KRAMERS–KRONIG DISPERSION RELATIONS 127  
        2.2.3 CAUSALITY AND STOKES' EQUATION 129  
        2.2.4 PULSE PROPAGATION IN A VISCOUS FLUID 130  
     2.3 SOUND WAVES AND SHEAR WAVES IN MARINE SEDIMENTS 134  
        2.3.1 THE BIOT THEORY 135  
        2.3.2 THE GRAIN-SHEARING THEORY 137  
     2.4 SOURCE OR RECEIVER IN MOTION 145  
        2.4.1 DOPPLER FREQUENCY SHIFTS (SOURCE STATIONARY, OBSERVER IN MOTION) 146  
        2.4.2 DOPPLER FREQUENCY SHIFTS (OBSERVER STATIONARY, SOURCE IN MOTION) 148  
        2.4.3 ACOUSTIC FIELD FROM A MOVING SOURCE 149  
     2.5 SOUND REFLECTION AND TRANSMISSION AT A FLUID–FLUID BOUNDARY 153  
        2.5.1 STRUCTURE OF THE SOLUTION 154  
        2.5.2 THE STATIONARY PHASE APPROXIMATION 158  
        2.5.3 PLANE-WAVE REFLECTION 159  
        2.5.4 WESTON'S EFFECTIVE DEPTH 163  
        2.5.5 PLANE-WAVE REFRACTION 164  
        2.5.6 THE LATERAL WAVE 167  
     2.6 THE “IDEAL” WAVEGUIDE 173  
        2.6.1 PLANE WAVES AND NORMAL MODES 173  
        2.6.2 THE ACOUSTIC FIELD IN THE IDEAL WAVEGUIDE 176  
        2.6.3 INTERMODAL INTERFERENCE 178  
     2.7 THE PEKERIS CHANNEL 179  
        2.7.1 THE INTEGRAL-TRANSFORM SOLUTION FOR THE FIELD 180  
        2.7.2 THE NORMAL MODE SOLUTION 182  
        2.7.3 THE CHARACTERISTIC EQUATION 184  
     2.8 THREE-DIMENSIONAL PROPAGATION 187  
        2.8.1 HORIZONTAL REFRACTION 188  
        2.8.2 THE “IDEAL” WEDGE 189  
        2.8.3 THE SHADOW EDGE 192  
        2.8.4 INTRAMODAL INTERFERENCE 195  
        2.8.5 THE PENETRABLE WEDGE 196  
     Acknowledgment 197  
     REFERENCES 197  
  3 - Sound Propagation Modeling 202  
     3.1 RAY MODELS 205  
        3.1.1 A PARTICULAR TYPE OF ANALYTIC 2-D RAY TRACING 206  
           3.1.1.1 Kinematic Ray Tracing 207  
           3.1.1.2 Dynamic Ray Tracing 207  
           3.1.1.3 Caustics 209  
           3.1.1.4 Coherent Computation of Propagation Loss and Propagation Time Series 209  
        3.1.2 EXAMPLE 211  
     3.2 WAVE NUMBER INTEGRATION OR SPECTRAL METHODS 213  
        3.2.1 SOLUTION OF THE DEPTH-DEPENDENT ODE SYSTEMS 215  
           3.2.1.1 Recursive Computation of Reflection-Coefficient Matrices for the Solid Bottom 216  
           3.2.1.2 Propagator Matrices for the Fluid Region 219  
           3.2.1.3 Alternative Treatment of the Fluid Region 220  
           3.2.1.4 Final Remarks 221  
        3.2.2 ADAPTIVE INTEGRATION 222  
        3.2.3 EXAMPLE 223  
     3.3 NORMAL MODE PROPAGATION MODELS 225  
        3.3.1 MODAL WAVE NUMBERS 226  
        3.3.2 MODE FUNCTIONS 227  
        3.3.3 EXCITATION COEFFICIENTS 229  
        3.3.4 RANGE-DEPENDENT MEDIA 230  
           3.3.4.1 Equations Relating the Modal Expansion Coefficients 231  
           3.3.4.2 Solution in Terms of Reflection-Coefficient Matrices 233  
           3.3.4.3 Final Remarks 234  
        3.3.5 EXAMPLES 235  
           3.3.5.1 Range-Invariant Media 235  
           3.3.5.2 Range-Dependent Media 239  
     3.4 PARABOLIC EQUATION METHODS 242  
        3.4.1 INTERFACE CONDITIONS AT THE VERTICAL RANGE-SEGMENT INTERFACES 244  
        3.4.2 NUMERICAL SOLUTION METHODS 245  
           3.4.2.1 Start Solution 245  
           3.4.2.2 Rational-Function Approximations for the Relevant Operators 247  
           3.4.2.3 Depth Discretization and Range Integration 249  
        3.4.3 EXTENDED AND ALTERNATIVE PE APPROACHES 250  
           3.4.3.1 Extension to Media That Vary Regionwise Smoothly With Range and Depth 250  
           3.4.3.2 Coordinate Transformation Techniques 251  
           3.4.3.3 Two-Way PE Approaches 252  
           3.4.3.4 Extension to Fluid-Solid Media 252  
        3.4.4 EXAMPLES 253  
     3.5 FINITE-DIFFERENCE AND FINITE-ELEMENT METHODS 256  
        3.5.1 ONE-DIMENSIONAL FEM AND FDM FOR PARABOLIC AND NORMAL-MODE EQUATIONS 257  
           3.5.1.1 Application to Normal Modes 258  
        3.5.2 TWO-DIMENSIONAL FEM AND FDM FOR THE HELMHOLTZ EQUATION 259  
           3.5.2.1 FEM Discretization 260  
           3.5.2.2 FDM Discretization 261  
           3.5.2.3 Methods to Solve the Linear Equation System and Possibilities to Reduce Its Size 262  
        3.5.3 TIME-DOMAIN MODELING 263  
           3.5.3.1 FEM Discretization 263  
           3.5.3.2 FDM Discretization 263  
           3.5.3.3 Numerical Dispersion, Time Integration, and Stability 264  
           3.5.3.4 Including Absorption 265  
           3.5.3.5 Some Recent Developments 265  
        3.5.4 EXAMPLES 266  
     3.6 3-D SOUND PROPAGATION MODELS 268  
        3.6.1 MODELING HORIZONTAL REFRACTION BY A SLOPING BOTTOM OR CHANGING SOUND-SPEED PROFILE 270  
           3.6.1.1 Fourier Transformation With Respect to the y-Coordinate 271  
           3.6.1.2 Equations Relating the Modal Expansion Coefficients 272  
           3.6.1.3 Solution in Terms of Reflection-Coefficient Matrices 273  
           3.6.1.4 Final Remarks 273  
        3.6.2 MODELING DIFFRACTION AROUND A CYLINDRICALLY SYMMETRIC ANOMALY 274  
           3.6.2.1 Fourier Series With Respect to the ? Coordinate 274  
           3.6.2.2 Equations Relating the Modal Expansion Coefficients 276  
           3.6.2.3 Solution in Terms of Reflection-Coefficient Matrices 277  
           3.6.2.4 Final Remarks 278  
        3.6.3 EXAMPLES 278  
     LIST OF ABBREVIATIONS AND SYMBOLS 280  
     Acknowledgments 281  
     REFERENCES 281  
  4 - Absorption of Sound in Seawater 290  
     4.1 PHYSICS AND PHENOMENA 290  
     4.2 EXPERIMENTAL DATA 292  
        4.2.1 ABSORPTION PRESSURE DEPENDENCE 295  
        4.2.2 ABSORPTION TEMPERATURE DEPENDENCE 297  
        4.2.3 PH DEPENDENCE OF ABSORPTION 299  
        4.2.4 SALINITY DEPENDENCE 299  
     4.3 SOUND ABSORPTION MECHANISMS 300  
        4.3.1 SOUND ABSORPTION IN FRESHWATER 300  
        4.3.2 MOLECULAR CHEMICAL RELAXATION PROCESSES 301  
           4.3.2.1 Temperature Dependence 303  
           4.3.2.2 Pressure Effects 305  
     4.4 FORMULAS AND EXPRESSIONS 305  
        4.4.1 FRANCOIS AND GARRISON EQUATION FOR SOUND ABSORPTION IN SEAWATER 305  
           4.4.1.1 Boric Acid Coefficients 306  
           4.4.1.2 Magnesium Sulfate Coefficients 307  
           4.4.1.3 Pure Water Contribution 307  
        4.4.2 AINSLIE AND MCCOLM SIMPLIFIED EQUATION FOR SOUND ABSORPTION IN SEAWATER 307  
     4.5 SYMBOLS AND ABBREVIATIONS 308  
     REFERENCES 309  
  5 - Scattering of Sound 314  
     5.1 PHYSICS AND PHENOMENA 314  
     5.2 SCATTERING FROM POINT-LIKE OBJECTS 320  
        5.2.1 SINGLE OBJECTS 320  
           5.2.1.1 Rigid and Elastic Spheres 320  
           5.2.1.2 Gas Bubbles 322  
           5.2.1.3 Single Fish 324  
           5.2.1.4 Canonically Shaped Objects 325  
           5.2.1.5 Submarines 327  
        5.2.2 MULTIPLE OBJECTS 330  
           5.2.2.1 Fish Schools 331  
           5.2.2.2 Bubble Clouds 331  
           5.2.2.3 Deep Scattering Layer 334  
           5.2.2.4 Suspended Sediments 335  
     5.3 SCATTERING FROM EXTENDED, NEARLY PLANE, ROUGH SURFACES 335  
        5.3.1 BRAGG SCATTERING 337  
        5.3.2 REFLECTION FROM FACETS 337  
        5.3.3 LAMBERT'S LAW 338  
        5.3.4 SCATTERING FROM THE SEA SURFACE 339  
        5.3.5 SCATTERING FROM THE SEABED 343  
     5.4 THEORETICAL BASIS FOR SCATTERING CALCULATIONS 349  
        5.4.1 THE PERTURBATION APPROXIMATION 349  
        5.4.2 THE HELMHOLTZ–KIRCHHOFF METHOD 352  
        5.4.3 SCATTERING FROM SURFACES WITH TWO SCALES OF ROUGHNESS 354  
     5.5 SCATTERING FROM CURVED, ROUGH SURFACES 357  
     5.6 REVERBERATION 363  
     5.7 SYMBOLS AND ABBREVIATIONS 370  
     REFERENCES 375  
  6 - Ambient Noise 380  
     6.1 PHYSICS AND PHENOMENA 380  
     6.2 SOURCES OF AMBIENT NOISE 381  
        6.2.1 TIDES AND HYDROSTATIC EFFECTS OF WAVES 381  
        6.2.2 SEISMIC ACTIVITIES 383  
        6.2.3 TURBULENCE 384  
        6.2.4 SURFACE PHENOMENA 384  
           6.2.4.1 Breaking Waves 385  
           6.2.4.2 Nonlinear Wave–Wave Interaction 386  
           6.2.4.3 Bubbles 387  
        6.2.5 PRECIPITATION 389  
        6.2.6 BIOLOGICAL ACTIVITY 391  
        6.2.7 ICE NOISE 392  
        6.2.8 SHIPPING 392  
        6.2.9 OTHER MAN-MADE (ANTHROPOGENIC) SOURCES 396  
        6.2.10 SEDIMENT FLOW–GENERATED NOISE 397  
        6.2.11 THERMAL NOISE 397  
     6.3 SPECTRA OF AMBIENT NOISE 398  
        6.3.1 DEEP-WATER SPECTRA 399  
        6.3.2 SHALLOW-WATER SPECTRA 400  
     6.4 DIRECTIVITY OF AMBIENT NOISE 401  
        6.4.1 NOISE PROPAGATION 401  
     6.5 COHERENCE OF AMBIENT NOISE 405  
     6.6 SELF-NOISE 407  
     6.7 AMPLITUDE DISTRIBUTIONS FOR UNDERWATER NOISE 409  
     6.8 SYMBOLS AND ABBREVIATIONS 414  
     REFERENCES 416  
  7 - Shallow-Water Acoustics 420  
     7.1 WHAT IS SHALLOW-WATER ACOUSTICS? 420  
        7.1.1 MILITARY APPLICATIONS 421  
        7.1.2 DUAL-USE APPLICATIONS 422  
        7.1.3 OCEAN SCIENCES APPLICATIONS 422  
        7.1.4 COMMERCIAL APPLICATIONS 423  
     7.2 PHYSICS AND PHENOMENA 423  
        7.2.1 SOURCE LEVEL TERM 423  
           7.2.1.1 Example: Integrating Pseudorandom Noise Sequences and Frequency Modulation Sweeps for Signal Gain 426  
        7.2.2 ARRAY GAIN TERM 428  
           7.2.2.1 Examples: Mode Filtration Techniques in Shallow Water 430  
              7.2.2.1.1 Time Resolution of Modes 430  
              7.2.2.1.2 Amplitude-Shaded Vertical Array Mode Resolution 430  
              7.2.2.1.3 Vertical Array Steering 432  
              7.2.2.1.4 Horizontal Array Steering 432  
              7.2.2.1.5 Focused Array Mode Filtration 433  
        7.2.3 TRANSMISSION LOSS TERM 433  
           7.2.3.1 Simple Geometric Spreading Intensity Arguments 433  
           7.2.3.2 Popular Propagation Theories and Their Application(s) to Shallow Water 434  
              7.2.3.2.1 Ray Theory 434  
              7.2.3.2.2 Normal Modes and Shallow Water 441  
              7.2.3.2.3 Vertical Modes and Horizontal Rays 448  
                 7.2.3.2.3.1 Example: Ducting Between Nonlinear Internal Waves 449  
              7.2.3.2.4 Parabolic Equation 451  
              7.2.3.2.5 Wave Number Integration 453  
        7.2.4 AMBIENT NOISE TERM 454  
        7.2.5 REVERBERATION TERM 459  
           7.2.5.1 The Bottom Boundary Layer 462  
           7.2.5.2 Water Column Reverberation 463  
           7.2.5.3 Sea Surface Scattering and Reverberation 463  
           7.2.5.4 The Sea Surface Plus Bubble Scattering and Reverberation 463  
     7.3 SOME ADDITIONAL TOPICS OF INTEREST IN SHALLOW-WATER ACOUSTICS 465  
        7.3.1 ONE- AND TWO-LAYER WATER COLUMN SOUND SPEED PROFILES IN SHALLOW-WATER ACOUSTICS 465  
        7.3.2 THE OPTIMUM FREQUENCY 466  
        7.3.3 ARRIVAL STRUCTURES IN SHALLOW-WATER AND RAY/MODE RESOLUTION 467  
        7.3.4 WAVEGUIDE INVARIANT 468  
        7.3.5 INTENSITY FLUCTUATION STATISTICS 469  
     7.4 SOME NEWER TOPICS 472  
        7.4.1 THE SHELF BREAK, SLOPE, AND CANYON REGIONS AND THE TRANSITION TO DEEP WATER 472  
        7.4.2 ARCTIC SHALLOW-WATER ACOUSTICS 473  
        7.4.3 CLIMATE CHANGE AND SHALLOW-WATER ACOUSTICS 474  
     LIST OF ACRONYMS 475  
     LIST OF SYMBOLS IN EQUATIONS 476  
     REFERENCES 477  
     APPENDIX 7.A1 480  
  8 - The Seafloor 486  
     8.1 BACKGROUND AND HISTORY 487  
     8.2 THE ORIGIN AND NATURE OF SEAFLOOR SEDIMENTS 488  
     8.3 ACOUSTICS OF SEDIMENTS 488  
        8.3.1 FLUID MODEL 489  
        8.3.2 ELASTIC MODEL 491  
        8.3.3 POROELASTIC MODEL 494  
     8.4 MODEL FOR SOUND SCATTERING BY THE SEAFLOOR 499  
        8.4.1 MODEL PARAMETERS 500  
        8.4.2 SCATTERING BY SEAFLOOR ROUGHNESS 501  
        8.4.3 SCATTERING BY SEAFLOOR HETEROGENEITY 503  
        8.4.4 SCATTERING MODEL EXAMPLES 505  
     8.5 SEDIMENT PHYSICAL PROPERTIES 511  
        8.5.1 GRAIN SIZE DISTRIBUTION 512  
        8.5.2 SEDIMENT BULK DENSITY AND POROSITY 516  
        8.5.3 PORE FLUID AND PORE SPACE PROPERTIES 518  
        8.5.4 PERMEABILITY 519  
        8.5.5 GRAIN PROPERTIES 520  
        8.5.6 SEDIMENT TYPE 520  
        8.5.7 SUMMARY OF SEDIMENT PROPERTIES 524  
     8.6 SEDIMENT GEOACOUSTIC PROPERTIES 524  
        8.6.1 SOUND SPEED AND ATTENUATION 526  
        8.6.2 SHEAR WAVE MEASUREMENTS 529  
        8.6.3 INDEX OF IMPEDANCE 532  
     8.7 SEAFLOOR ROUGHNESS 534  
        8.7.1 MEASUREMENT OF SEAFLOOR ROUGHNESS 535  
        8.7.2 STATISTICAL CHARACTERIZATION OF SEAFLOOR ROUGHNESS 537  
        8.7.3 PREDICTION OF SEAFLOOR ROUGHNESS FROM SEDIMENT PHYSICAL PROPERTIES 537  
     8.8 SEAFLOOR HETEROGENEITY 539  
        8.8.1 MEASUREMENTS OF SEDIMENT VOLUME HETEROGENEITY 540  
        8.8.2 GAS IN SEDIMENTS 541  
     8.9 SEAFLOOR IDENTIFICATION AND CHARACTERIZATION BY USE OF SONAR 543  
        8.9.1 FEATURE CLUSTERING 546  
        8.9.2 IMAGE SEGMENTATION 548  
        8.9.3 REFLECTION 548  
        8.9.4 SCATTERING STRENGTH 549  
        8.9.5 MODEL FITTING TO ECHO TIME SERIES 554  
     LIST OF SYMBOLS 557  
     REFERENCES 560  
  9 - Inverse Methods in Underwater Acoustics 570  
     9.1 INTRODUCTION 570  
     9.2 SOME BASIC MATHEMATICAL RELATIONSHIPS 572  
     9.3 SOURCE LOCALIZATION BY MATCHED FIELD PROCESSING 573  
     9.4 GEOACOUSTIC INVERSION 576  
        9.4.1 GEOACOUSTIC MODELS 576  
        9.4.2 LINEAR INVERSIONS FOR GEOACOUSTIC PROFILES 578  
        9.4.3 GEOACOUSTIC INVERSION BY BAYESIAN INFERENCE 580  
        9.4.4 BAYESIAN MATCHED FIELD INVERSION 584  
           9.4.4.1 Bayesian Matched Field Inversion by Optimization 584  
           9.4.4.2 Bayesian Matched Field Inversion by Integration of the a Posteriori Probability Density 589  
     9.5 OCEAN ACOUSTIC TOMOGRAPHY 593  
        9.5.1 INVERSION OF TRAVEL TIMES 594  
        9.5.2 ACOUSTIC THERMOMETRY 595  
        9.5.3 ACOUSTIC TOMOGRAPHY IN SHALLOW WATER 597  
     REFERENCES 598  
  10 - Sonar Systems 604  
     10.1 SONAR SYSTEM APPLICATIONS 605  
     10.2 SONAR SYSTEM TYPES 608  
        10.2.1 TRANSDUCER MATERIALS 608  
        10.2.2 PROJECTORS AND HYDROPHONES 613  
        10.2.3 PARAMETERS OF PIEZOCERAMICS 618  
        10.2.4 TRANSDUCER GEOMETRIES 623  
           10.2.4.1 Plates 624  
           10.2.4.2 Cylindrical Elements 624  
           10.2.4.3 Spherical Elements 628  
           10.2.4.4 Tonpilz Transducers 630  
           10.2.4.5 Flextensional Transducers 633  
           10.2.4.6 Flexural Transducers 635  
        10.2.5 ACOUSTIC FIELD QUALITIES OF TRANSDUCERS 638  
           10.2.5.1 Single-Element Transducers 639  
              10.2.5.1.1 The Pole Concept 639  
              10.2.5.1.2 Piston Sources 643  
              10.2.5.1.3 Hydrophones 654  
           10.2.5.2 Arrays 661  
              10.2.5.2.1 Array Types 662  
              10.2.5.2.2 Array Qualities 669  
              10.2.5.2.3 Towed Arrays 677  
     10.3 SINGLE-BEAM ECHO SOUNDERS 681  
     10.4 MULTIBEAM ECHO SOUNDERS 689  
        10.4.1 MULTIBEAM ECHO SOUNDER STRUCTURE 696  
           10.4.1.1 Projector Unit 697  
           10.4.1.2 Receiver Unit 698  
           10.4.1.3 Sonar Processor Unit 699  
           10.4.1.4 Auxiliary Equipment 701  
        10.4.2 MULTIBEAM ECHO SOUNDER APPLICATIONS 702  
           10.4.2.1 Bathymetry 702  
           10.4.2.2 Snippets 705  
           10.4.2.3 Side-Scan Data 705  
        10.4.3 MULTIBEAM ECHO SOUNDER PERFORMANCE LIMITATIONS 705  
     10.5 SIDE-SCAN SONAR 706  
        10.5.1 SINGLE-ROW SSS 706  
        10.5.2 MULTIROW SSS 712  
     10.6 SYNTHETIC APERTURE SONAR 713  
     10.7 OTHER SONAR TYPES 718  
     10.8 TRANSDUCER CALIBRATION 723  
        10.8.1 DEFINITIONS 723  
        10.8.2 RECIPROCITY CALIBRATIONS 725  
        10.8.3 OTHER CALIBRATION METHODS 729  
     10.9 SONAR SYSTEM EXAMPLE CALCULATIONS 734  
     10.10 SONAR DESIGN CALCULATIONS 740  
        10.10.1 TONPILZ TRANSDUCER AND HYDROPHONE CALCULATIONS 741  
        10.10.2 EQUIVALENT CIRCUITS 745  
        10.10.3 FINITE-ELEMENT TECHNIQUES 749  
     10.11 SYMBOLS AND ABBREVIATIONS 753  
     REFERENCES 755  
  11 - Signal Processing 760  
     11.1 BACKGROUND AND DEFINITIONS 760  
        11.1.1 SIGNALS AND NOISE IN UNDERWATER ACOUSTICS 760  
        11.1.2 WHAT IS “SIGNAL PROCESSING” AND WHY DO WE DO IT? 761  
        11.1.3 STRUCTURE OF THIS CHAPTER 763  
        11.1.4 OTHER RESOURCES 763  
        11.1.5 MATHEMATICAL NOTATION 764  
        11.1.6 LIST OF SYMBOLS AND NOTATION 764  
        11.1.7 LIST OF ABBREVIATIONS 765  
     11.2 CHARACTERIZING THE SIGNAL AND NOISE 766  
        11.2.1 SAMPLING AND QUANTIZING ANALOG SIGNALS 766  
        11.2.2 TIME AND FREQUENCY CHARACTERIZATION 767  
           11.2.2.1 Signal Consistency: Deterministic and Random Signals 768  
           11.2.2.2 Temporal Characterization 768  
           11.2.2.3 Spectral Content: The Fourier Transform and Spectral Density 769  
        11.2.3 DISCRETE FOURIER TRANSFORM 772  
        11.2.4 RANDOM PROCESSES: SPECTRA AND CORRELATION FUNCTIONS 773  
        11.2.5 CROSS-SPECTRA AND COHERENCE 775  
        11.2.6 CEPSTRUM 775  
     11.3 FILTERING 776  
        11.3.1 FILTER TYPES 776  
        11.3.2 PERFORMANCE METRICS, DESIGN, AND IMPLEMENTATION 777  
           11.3.2.1 Filtering Performance Metrics 777  
           11.3.2.2 Digital Filter Design and Implementation 777  
        11.3.3 BAND-PASS SIGNALS: DIGITAL DOWN-CONVERSION 781  
        11.3.4 WINDOWING FOR SIDE-LOBE SUPPRESSION 781  
        11.3.5 DATA-DEPENDENT OR ADAPTIVE FILTERING 784  
     11.4 DETECTION 784  
        11.4.1 PERFORMANCE METRICS, DESIGN, IMPLEMENTATION, AND ANALYSIS PROCEDURE 786  
           11.4.1.1 Detection Performance Metrics 786  
           11.4.1.2 Required SNR and Detection Threshold 787  
           11.4.1.3 Detector Design and Implementation 788  
           11.4.1.4 Analysis of Detection Performance 790  
        11.4.2 STRUCTURED DESIGN APPROACHES 791  
        11.4.3 DETECTING SIGNALS OF KNOWN FORM: CORRELATION PROCESSING 794  
           11.4.3.1 Example: Doppler Filter Bank 794  
           11.4.3.2 Pulse Compression, Matched Filtering, and the Ambiguity Function 796  
           11.4.3.3 Example: LFM Pulse Compression 797  
           11.4.3.4 Other Applications in Underwater Acoustics 798  
        11.4.4 DETECTING RANDOM OR UNKNOWN SIGNALS: ENERGY DETECTOR 798  
        11.4.5 DETECTING UNKNOWN SIGNAL ONSET: PAGE'S TEST 799  
        11.4.6 NORMALIZING FOR CONSTANT FALSE ALARM RATE 801  
     11.5 ESTIMATION 803  
        11.5.1 PERFORMANCE METRICS, DESIGN, IMPLEMENTATION, AND ANALYSIS PROCEDURE 804  
           11.5.1.1 Estimation Performance Metrics 804  
           11.5.1.2 Estimator Design and Implementation Process 805  
           11.5.1.3 Estimator Analysis Procedure and the Cramer-Rao Lower Bound 805  
        11.5.2 STRUCTURED DESIGN APPROACHES 806  
           11.5.2.1 Maximum Likelihood Estimation 806  
           11.5.2.2 Method of Moments Estimation 808  
           11.5.2.3 Other Approaches 809  
        11.5.3 SPECTROGRAM, PERIODOGRAM, AND POWER SPECTRAL DENSITY ESTIMATION 809  
           11.5.3.1 Periodogram for Spectral Density Estimation 811  
           11.5.3.2 Zero-Padding the DFT 814  
        11.5.4 TIME-DELAY ESTIMATION 815  
        11.5.5 BEAMFORMING AND ANGLE OF ARRIVAL ESTIMATION 818  
     REFERENCES 821  
  12 - Bio- and Fishery Acoustics 826  
     12.1 INTRODUCTION 826  
     12.2 MARINE LIFE: FROM WHALES TO PLANKTON 827  
     12.3 ACOUSTIC SCATTERING BY MARINE LIFE 828  
        12.3.1 ZOOPLANKTON SCATTERING 830  
        12.3.2 SWIM BLADDER SCATTERING 832  
        12.3.3 FISH BODY SCATTERING 834  
        12.3.4 LARGE-BODY SCATTERING 835  
        12.3.5 MANY-BODY SCATTERING 838  
     12.4 ACTIVE IMAGING SYSTEMS 841  
        12.4.1 SINGLE-BEAM ECHO SOUNDERS 841  
        12.4.2 SIDE-SCAN SONARS 845  
        12.4.3 MULTIBEAM ECHO SOUNDERS 846  
        12.4.4 COMBINING SENSORS 849  
     12.5 MARINE LIFE AND SOUND 852  
        12.5.1 GENERAL POINTS 852  
        12.5.2 MARINE MAMMALS 853  
        12.5.3 FISH, TURTLES, AND INVERTEBRATES 855  
     12.6 PASSIVE ACOUSTIC MONITORING 857  
     12.7 SELECTED PRACTICAL APPLICATIONS 860  
        12.7.1 ACTIVE ACOUSTICS: FISH SURVEY 860  
        12.7.2 PASSIVE ACOUSTICS: AMBIENT NOISE MONITORING 861  
        12.7.3 ACOUSTIC TELEMETRY: FISH BEHAVIOR 863  
     12.8 CONCLUSIONS: FUTURE DEVELOPMENTS 864  
     REFERENCES 866  
  13 - Finite-Amplitude Waves 874  
     13.1 PHYSICS AND NONLINEAR PHENOMENA 875  
        13.1.1 HARMONIC DISTORTION 875  
        13.1.2 FOCUSED SOUND FIELDS 878  
        13.1.3 CAVITATION 880  
        13.1.4 ACOUSTIC RADIATION PRESSURE AND ACOUSTIC STREAMING 882  
     13.2 NONLINEAR UNDERWATER ACOUSTICS 883  
        13.2.1 PARAMETRIC ACOUSTIC TRANSMITTING ARRAYS 884  
        13.2.2 PARAMETRIC ACOUSTIC RECEIVING ARRAYS 889  
        13.2.3 APPLICATIONS OF THE PARAMETRIC ACOUSTIC ARRAY 890  
     13.3 UNDERWATER EXPLOSIONS 895  
        13.3.1 THE SHOCK WAVE 895  
        13.3.2 THE GAS BUBBLE 897  
        13.3.3 OTHER SOURCES OF HIGH-INTENSITY SOUND 898  
     13.4 LIST OF SYMBOLS AND ABBREVIATIONS 901  
     REFERENCES 903  
  14 - Underwater Acoustic Measurements and Their Applications 906  
     14.1 INTRODUCTION 906  
     14.2 ACOUSTICS AND MARINE RENEWABLE ENERGY DEVELOPMENTS 907  
        14.2.1 NOISE DURING THE CONSTRUCTION PHASE 908  
        14.2.2 NOISE DURING OPERATION 910  
     14.3 UNDERWATER ACOUSTICS IN NUCLEAR-TEST-BAN TREATY MONITORING 911  
        14.3.1 THE HYDROACOUSTIC NETWORK OF THE CTBTO 913  
        14.3.2 INSTALLATION AND PERFORMANCE OF THE NEWEST IMS HYDROACOUSTIC STATION: HA03, ROBINSON CRUSOE ISLAND, JUAN FERNÁNDEZ ARCHIPEL ... 914  
     14.4 CHARACTERIZATION OF NOISE FROM SHIPS 916  
        14.4.1 GENERAL CHARACTERIZATION OF NOISE PRODUCED BY SHIPS 916  
        14.4.2 NOISE GENERATED BY A PROPULSION SYSTEM 918  
        14.4.3 NOISE GENERATED BY A PROPELLER 919  
        14.4.4 IDENTIFICATION OF ACOUSTIC WAVES EMITTED BY A MOVING SHIP 919  
        14.4.5 SUMMARY 920  
     14.5 UNDERWATER SOUNDSCAPES 921  
     14.6 UNDERWATER ACOUSTIC COMMUNICATIONS 925  
     14.7 UNDERWATER ARCHAEOLOGY 930  
        14.7.1 THE WORKING CYCLE OF FIELD MARINE ARCHAEOLOGISTS 930  
           14.7.1.1 Large Area Search 931  
           14.7.1.2 Local Surveying and Mapping 932  
           14.7.1.3 Evolving Trends: A Technological Future for the Exploration of Deep Water Archaeological Sites 933  
     14.8 APPLICATIONS OF UNDERWATER ACOUSTICS IN POLAR ENVIRONMENTS 934  
        14.8.1 INTRODUCTION 934  
        14.8.2 ARCTIC 935  
        14.8.3 ANTARCTIC 938  
     14.9 TANK EXPERIMENTS 940  
        14.9.1 INTRODUCTION 940  
        14.9.2 DESCRIPTION OF DIFFERENT CATEGORIES OF TANKS USED FOR UNDERWATER APPLICATIONS 941  
        14.9.3 CONCLUSION 944  
     14.10 ACOUSTIC POSITIONING AT SEA 944  
        14.10.1 LBL POSITIONING DEVELOPMENT 945  
        14.10.2 ULTRASHORT BASELINE (USBL) POSITIONING 946  
        14.10.3 EFFECTS OF NOISE 947  
        14.10.4 IMPROVED CODING 947  
        14.10.5 COORDINATION WITH INERTIAL SENSORS 947  
     14.11 OCEAN OBSERVING SYSTEMS AND OCEAN OBSERVATORIES, OCEANOGRAPHERS, AND ACOUSTICIANS—A PERSONAL PERSPECTIVE 948  
        14.11.1 INTRODUCTION 948  
        14.11.2 OCEANOGRAPHERS 949  
        14.11.3 ACOUSTICIANS 950  
        14.11.4 FUTURE DIRECTIONS 950  
     14.12 APPLICATIONS OF UNDERWATER ACOUSTICS TO MILITARY PURPOSES 951  
        14.12.1 PASSIVE SONAR 952  
        14.12.2 ACTIVE SONAR 955  
     REFERENCES 957  
  Index 966  
     A 966  
     B 967  
     C 968  
     D 968  
     E 969  
     F 969  
     G 970  
     H 970  
     I 970  
     J 971  
     K 971  
     L 971  
     M 971  
     N 972  
     O 972  
     P 973  
     Q 974  
     R 974  
     S 974  
     T 979  
     U 980  
     V 981  
     W 981  
     Y 981  
     Z 981  


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