High-Frequency Seafloor Acoustics (eBook)
XVI, 616 Seiten
Springer New York (Verlag)
978-0-387-36945-7 (ISBN)
This book is a research monograph on high-Frequency Seafloor Acoustics. It is the first book in a new series sponsored by the Office of Naval Research on the latest research in underwater acoustics. It provides a critical evaluation of the data and models pertaining to high-frequency acoustic interaction with the seafloor, which will be of interest to researchers in underwater acoustics and to developers of sonars. Models and data are presented so as to be readily usable, backed up by extensive explanation. Much of the data is new, and the discussion in on two levels: concise descriptions in the main text backed up by extensive technical appendices.
The efficacy of sound to penetrate the seas made acoustic systems in the past century the leading tools for sensing objects in and measuring properties of the seas. For over sixty years The United States Office of Naval Research (ONR) has been a major sponsor of undersea research and development at universities, national laboratories, and industrial organizations. App- priately ONR is the sponsor of this monograph series. The intent of the series is to summarize recent accomplishments in, and to outline perspectives for, underwater acoustics in specific fields of research. The general field has escalated in importance and spread broadly with ri- ness and depth of understanding. It has also, quite naturally, become more specialized. The goal of this series is to present monographs that critically review both past and recent accomplishments in order to address the sho- comings in present understanding. In this way, these works will bridge the gaps in understanding among the specialists and favorably color the direction of new research and development. Each monograph is intended to be a stand-alone advanced contribution to the field. We trust that the reader will also find that each is a critical introduction to related specialized topics of interest as well.
Acknowledgments 8
Contents 9
1 Introduction 15
1.1 Applications 16
1.2 Research on Seafloor Scattering 17
1.3 Organization of Monograph 18
2 Basic Concepts and Definitions 21
2.1 Geophysical Properties 21
2.2 Sediment Wave Theories 28
2.3 Reflection and Scattering 31
3 The Nature of Marine Sediments 42
3.1 The Origin and Classification of Coastal Sediments 43
3.2 Sediment Structure 45
3.3 Bubbles in Sediment 64
3.4 Effects of Hydrodynamic and Biological Processes 70
3.5 Research Issues 85
4 Physical Properties 87
4.1 Sediment Grain Size Distribution 88
4.2 Sand Grain Morphology 101
4.3 Phase Relationships: Porosity, Void Ratio, Water Content, and Bulk Density 104
4.4 Sediment Conductance 111
4.5 Grain Properties 122
4.6 Factors Affecting Fluid Motion 130
4.7 Pore Water Properties 131
4.8 Research Issues 134
5 Geoacoustic Properties 135
5.1 Compressional Wave Speed and Attenuation 137
5.2 Shear Wave Speed and Attenuation 163
5.3 Biot’s Slow Wave 173
5.4 Sound Speed and Attenuation versus Frequency 177
5.5 Bulk Density Regressions 179
5.6 Properties of Rock 181
5.7 Research Issues 182
6 Seafloor Roughness 183
6.1 Statistical Characterization of Seafloor Roughness 185
6.2 Measurement of Seafloor Roughness 188
6.3 Examples of Seafloor Roughness Spectra 194
6.4 Temporal Variability in Seafloor Roughness 196
6.5 Validity of Power-Law Assumption for Roughness Spectra 203
6.6 Relationships between Roughness and Sediment Physical Properties 205
6.7 Relationship between Spectral Parameters 207
6.8 Summary 209
6.9 Research Issues 210
7 Sediment Heterogeneity 213
7.1 Measurement of Heterogeneity 219
7.2 Statistical Characterization of Continuous Heterogeneity 234
7.3 Relationships Connecting Fluctuating Parameters 239
7.4 Measurement Bias Due to Finite Resolution 241
7.5 Examples of Heterogeneity Statistics 246
7.6 Research Issues 255
8 Fluid Theories 256
8.1 Equations of Motion 258
8.2 Plane Waves 259
8.3 Losses and Energy Flux 261
8.4 Boundary Conditions 264
8.5 Reflection and Transmission 265
8.6 Nonplane Waves, Flat Seafloors 270
8.7 Wood’s Equation 275
8.8 Research Issues 276
9 Elastic Theories 277
9.1 Equations of Motion 278
9.2 Plane Waves 279
9.3 Losses 281
9.4 Boundary Conditions 281
9.5 Reflection and Transmission 283
9.6 Nonplane Waves 286
9.7 Gassmann’s Equations 287
9.8 Buckingham’s Theory 288
9.9 Research Issues 293
10 Poroelastic Theories 294
10.1 Biot Theory 294
10.2 Effective Density Fluid Approximation 307
10.3 Experimental Tests of Biot Theory 311
10.4 Theoretical Alternatives 314
10.5 Research Issues 315
11 Reflection 317
11.1 Reflection Measurement Issues 318
11.2 Reflection Data Compared with Theory and Models 320
11.3 Research Issues 328
12 Seafloor Scattering Experiments 329
12.1 Monostatic Experiments 331
12.2 Bistatic Experiments 337
12.3 Research Issues 338
13 Roughness Scattering Models 339
13.1 General Properties of Roughness-Scattering Models 340
13.2 Small-Roughness Perturbation Approximation 346
13.3 Kirchhoff Approximation 361
13.4 Small-Slope Approximation 369
13.5 Composite-Roughness Approximation 370
13.6 Scattering by Discrete Features 376
13.7 Mathematical Accuracy of Approximations 377
13.8 Research Issues 384
14 Sediment Volume Scattering 385
14.1 Fluid Sediment Volume Scattering Models 386
14.2 Elastic Sediment Volume Scattering 409
14.3 Research Issues 414
15 Acoustic Penetration of the Seafloor 415
15.1 Roughness Perturbation Model 419
15.2 Mathematical Accuracy 427
15.3 Research Issues 427
16 Backscatter Statistics 429
16.1 General Statistical Properties of Backscattered Field 432
16.2 Gaussian Statistics 433
16.3 Non-Gaussian Statistics 438
16.4 Research Issues 450
A List of Symbols 451
B Calculation of Properties of Seawater 462
B.1 Seawater Density 463
B.2 Sound Speed in Seawater 465
B.3 Seawater Absorption and Attenuation 467
B.4 Seawater Viscosity 469
B.5 Electrical Conductivity of Seawater 472
B.6 Practical Salinity 475
C Coefficient of Variation of Sediment Parameters 477
D Roughness and Volume Statistics 480
D.1 Interface Roughness 480
D.2 Volume Heterogeneity 484
E Complex Representation of Signals 490
F Acoustic Transducers 492
G Acoustic Measurements 497
G.1 Reflection Measurements 497
G.2 Scattering Measurements 499
H Measurement Units and Decibels 513
I Causality Constraints on Speed–Attenuation Relations 515
J The Scattering Cross Section and Plane Waves 523
J.1 General Expressions 523
J.2 Far-Field Issues 527
K Rough-Interface Perturbation Theory 533
K.1 Fluid–Fluid Boundary 535
K.2 Fluid–Elastic Boundary 540
K.3 Fluid–Poroelastic Boundary 544
L The Kirchhoff and Small-Slope Approximations 545
L.1 Kirchhoff Approximation 545
L.2 Small-Slope Approximation 546
L.3 The Incoherent Reflection Coefficient 547
L.4 High-Frequency Limit of the Kirchhoff Approximation 549
M Volume Perturbation Theory 551
M.1 Fluid Sediment 551
M.2 Elastic Sediment 558
References 562
Index 607
| Erscheint lt. Verlag | 2.8.2007 |
|---|---|
| Reihe/Serie | The Underwater Acoustics Series |
| Zusatzinfo | XVI, 616 p. 50 illus. |
| Verlagsort | New York |
| Sprache | englisch |
| Themenwelt | Naturwissenschaften ► Geowissenschaften ► Geografie / Kartografie |
| Naturwissenschaften ► Geowissenschaften ► Hydrologie / Ozeanografie | |
| Naturwissenschaften ► Physik / Astronomie | |
| Technik | |
| Schlagworte | Geophysics • High-frequency acoustics • hydrogeology • Marine • Natur • Sonar • Statistics • Wave |
| ISBN-10 | 0-387-36945-7 / 0387369457 |
| ISBN-13 | 978-0-387-36945-7 / 9780387369457 |
| Haben Sie eine Frage zum Produkt? |
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