Subjects -> EARTH SCIENCES (Total: 771 journals)
    - EARTH SCIENCES (527 journals)
    - GEOLOGY (94 journals)
    - GEOPHYSICS (33 journals)
    - HYDROLOGY (29 journals)
    - OCEANOGRAPHY (88 journals)

EARTH SCIENCES (527 journals)                  1 2 3 | Last

Showing 1 - 200 of 371 Journals sorted by number of followers
Nature Geoscience     Full-text available via subscription   (Followers: 161)
IEEE Geoscience and Remote Sensing Letters     Hybrid Journal   (Followers: 151)
International Journal of Remote Sensing     Hybrid Journal   (Followers: 144)
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 143)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 133)
Journal of the Atmospheric Sciences     Hybrid Journal   (Followers: 83)
Ocean & Coastal Management     Hybrid Journal   (Followers: 62)
Marine Policy     Hybrid Journal   (Followers: 60)
International Journal of Geographical Information Science     Hybrid Journal   (Followers: 55)
Geochimica et Cosmochimica Acta     Hybrid Journal   (Followers: 54)
ICES Journal of Marine Science: Journal du Conseil     Hybrid Journal   (Followers: 53)
Natural Hazards     Hybrid Journal   (Followers: 53)
Journal of Earth System Science     Open Access   (Followers: 52)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 44)
Hydrological Processes     Hybrid Journal   (Followers: 44)
Estuarine, Coastal and Shelf Science     Hybrid Journal   (Followers: 41)
Geophysical Journal International     Hybrid Journal   (Followers: 40)
Journal of Hydrologic Engineering     Full-text available via subscription   (Followers: 40)
Groundwater     Hybrid Journal   (Followers: 37)
International Journal of Earth Sciences     Hybrid Journal   (Followers: 37)
International Journal of Applied Earth Observation and Geoinformation     Open Access   (Followers: 36)
Physics of the Earth and Planetary Interiors     Hybrid Journal   (Followers: 34)
Journal of Atmospheric and Oceanic Technology     Hybrid Journal   (Followers: 33)
Geomorphology     Hybrid Journal   (Followers: 33)
Chemical Geology     Hybrid Journal   (Followers: 31)
Marine Geology     Hybrid Journal   (Followers: 31)
Geology Today     Hybrid Journal   (Followers: 31)
Marine Environmental Research     Hybrid Journal   (Followers: 31)
Journal of Quaternary Science     Hybrid Journal   (Followers: 31)
Reviews of Modern Physics     Full-text available via subscription   (Followers: 30)
Journal of Geotechnical and Geoenvironmental Engineering     Full-text available via subscription   (Followers: 30)
Journal of Geology     Full-text available via subscription   (Followers: 30)
Coastal Management     Hybrid Journal   (Followers: 29)
Advances In Physics     Hybrid Journal   (Followers: 29)
GPS Solutions     Hybrid Journal   (Followers: 28)
Bulletin of the Seismological Society of America     Full-text available via subscription   (Followers: 26)
Landslides     Hybrid Journal   (Followers: 26)
Journal of Structural Geology     Hybrid Journal   (Followers: 26)
Quaternary Science Reviews     Hybrid Journal   (Followers: 26)
Ground Water Monitoring & Remediation     Hybrid Journal   (Followers: 25)
Geoforum     Hybrid Journal   (Followers: 25)
Earth Surface Processes and Landforms     Hybrid Journal   (Followers: 25)
Environmental Geology     Hybrid Journal   (Followers: 25)
Tectonophysics     Hybrid Journal   (Followers: 24)
Geocarto International     Hybrid Journal   (Followers: 23)
Coral Reefs     Hybrid Journal   (Followers: 22)
Bulletin of Volcanology     Hybrid Journal   (Followers: 22)
Hydrogeology Journal     Hybrid Journal   (Followers: 21)
Hydrobiologia     Hybrid Journal   (Followers: 21)
Tellus A     Open Access   (Followers: 21)
Marine and Petroleum Geology     Hybrid Journal   (Followers: 21)
Water Resources     Hybrid Journal   (Followers: 21)
Journal of Plasma Physics     Hybrid Journal   (Followers: 21)
Earthquake Spectra     Hybrid Journal   (Followers: 20)
Tellus B     Open Access   (Followers: 20)
Journal of Marine Research     Full-text available via subscription   (Followers: 20)
Sedimentary Geology     Hybrid Journal   (Followers: 20)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 19)
Geophysics     Full-text available via subscription   (Followers: 19)
Quaternary Research     Full-text available via subscription   (Followers: 19)
Geological Journal     Hybrid Journal   (Followers: 19)
Global and Planetary Change     Hybrid Journal   (Followers: 18)
Physics of Metals and Metallography     Hybrid Journal   (Followers: 18)
African Journal of Aquatic Science     Hybrid Journal   (Followers: 17)
Computational Geosciences     Hybrid Journal   (Followers: 17)
Journal of Volcanology and Geothermal Research     Hybrid Journal   (Followers: 17)
Natural Hazards Review     Full-text available via subscription   (Followers: 16)
Geological Magazine     Hybrid Journal   (Followers: 16)
The Holocene     Hybrid Journal   (Followers: 16)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 16)
Journal of Metamorphic Geology     Hybrid Journal   (Followers: 15)
Journal of Applied Geophysics     Hybrid Journal   (Followers: 15)
Journal of Asian Earth Sciences     Hybrid Journal   (Followers: 15)
Sedimentology     Hybrid Journal   (Followers: 15)
Ocean Development & International Law     Hybrid Journal   (Followers: 15)
Applied Geochemistry     Hybrid Journal   (Followers: 14)
Quaternary International     Hybrid Journal   (Followers: 14)
Journal of the World Aquaculture Society     Hybrid Journal   (Followers: 13)
Journal of Hydro-environment Research     Full-text available via subscription   (Followers: 13)
Pramana     Open Access   (Followers: 13)
Soil Dynamics and Earthquake Engineering     Hybrid Journal   (Followers: 13)
Electromagnetics     Hybrid Journal   (Followers: 13)
Ocean Modelling     Hybrid Journal   (Followers: 12)
European Journal of Mineralogy     Hybrid Journal   (Followers: 12)
Frontiers of Earth Science     Hybrid Journal   (Followers: 12)
Continental Shelf Research     Hybrid Journal   (Followers: 12)
Computers and Geotechnics     Hybrid Journal   (Followers: 12)
Arctic, Antarctic, and Alpine Research     Open Access   (Followers: 12)
Pure and Applied Geophysics     Hybrid Journal   (Followers: 12)
CATENA     Hybrid Journal   (Followers: 11)
Journal of Petrology     Hybrid Journal   (Followers: 11)
Ore Geology Reviews     Hybrid Journal   (Followers: 11)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 11)
Applied Geophysics     Hybrid Journal   (Followers: 11)
Journal of African Earth Sciences     Hybrid Journal   (Followers: 11)
IEEE Journal of Oceanic Engineering     Hybrid Journal   (Followers: 11)
Marine Mammal Science     Hybrid Journal   (Followers: 10)
Cretaceous Research     Hybrid Journal   (Followers: 10)
Earth Interactions     Open Access   (Followers: 10)
Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia     Hybrid Journal   (Followers: 10)
Bulletin of Earthquake Engineering     Hybrid Journal   (Followers: 10)
Gondwana Research     Hybrid Journal   (Followers: 10)
Physics of Plasmas     Hybrid Journal   (Followers: 10)
Journal of Seismology     Hybrid Journal   (Followers: 9)
Physik in unserer Zeit     Hybrid Journal   (Followers: 9)
Lithos     Hybrid Journal   (Followers: 9)
Limnology     Hybrid Journal   (Followers: 9)
Acta Geophysica     Hybrid Journal   (Followers: 9)
Journal of Contemporary Physics (Armenian Academy of Sciences)     Hybrid Journal   (Followers: 9)
Journal of Marine Systems     Hybrid Journal   (Followers: 9)
Geotectonics     Hybrid Journal   (Followers: 9)
Facies     Hybrid Journal   (Followers: 9)
Comptes Rendus : Geoscience     Open Access   (Followers: 9)
Journal of Geodesy     Hybrid Journal   (Followers: 9)
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards     Hybrid Journal   (Followers: 8)
Geophysical & Astrophysical Fluid Dynamics     Hybrid Journal   (Followers: 8)
Natural Resources Research     Hybrid Journal   (Followers: 8)
Geobiology     Hybrid Journal   (Followers: 8)
Quaternary Geochronology     Hybrid Journal   (Followers: 8)
Earthquake Engineering and Engineering Vibration     Hybrid Journal   (Followers: 8)
Geophysical Prospecting     Hybrid Journal   (Followers: 7)
Journal of Systematic Palaeontology     Hybrid Journal   (Followers: 7)
Physics of the Solid State     Hybrid Journal   (Followers: 7)
Plasma Physics Reports     Hybrid Journal   (Followers: 7)
Precambrian Research     Hybrid Journal   (Followers: 7)
Ocean Engineering     Hybrid Journal   (Followers: 6)
Petrology     Full-text available via subscription   (Followers: 6)
Applied Clay Science     Hybrid Journal   (Followers: 6)
Journal of Sea Research     Hybrid Journal   (Followers: 6)
Geochemistry : Exploration, Environment, Analysis     Hybrid Journal   (Followers: 6)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Geo-Marine Letters     Hybrid Journal   (Followers: 6)
Journal of Coastal Conservation     Hybrid Journal   (Followers: 6)
Applied Ocean Research     Hybrid Journal   (Followers: 6)
Rock Mechanics and Rock Engineering     Hybrid Journal   (Followers: 6)
Chinese Geographical Science     Hybrid Journal   (Followers: 6)
Journal of Geodynamics     Hybrid Journal   (Followers: 6)
Resource Geology     Hybrid Journal   (Followers: 6)
Marine and Freshwater Research     Hybrid Journal   (Followers: 6)
Ocean Dynamics     Hybrid Journal   (Followers: 6)
International Journal of Geomechanics     Full-text available via subscription   (Followers: 6)
Island Arc     Hybrid Journal   (Followers: 5)
Geofluids     Open Access   (Followers: 5)
Computational Mathematics and Mathematical Physics     Hybrid Journal   (Followers: 5)
Marine Geophysical Researches     Hybrid Journal   (Followers: 5)
Geochemistry     Hybrid Journal   (Followers: 5)
Permafrost and Periglacial Processes     Hybrid Journal   (Followers: 5)
Zeitschrift für Geomorphologie     Full-text available via subscription   (Followers: 5)
Terra Nova     Hybrid Journal   (Followers: 5)
Energy Exploration & Exploitation     Open Access   (Followers: 4)
Organic Geochemistry     Hybrid Journal   (Followers: 4)
Mineralium Deposita     Hybrid Journal   (Followers: 4)
Marine Geodesy     Hybrid Journal   (Followers: 4)
Limnologica     Hybrid Journal   (Followers: 4)
Meteorologische Zeitschrift     Full-text available via subscription   (Followers: 4)
Letters in Mathematical Physics     Hybrid Journal   (Followers: 4)
Geostandards and Geoanalytical Research     Hybrid Journal   (Followers: 3)
Surveys in Geophysics     Hybrid Journal   (Followers: 3)
Lithology and Mineral Resources     Hybrid Journal   (Followers: 3)
Russian Geology and Geophysics     Hybrid Journal   (Followers: 3)
Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 3)
JETP Letters     Hybrid Journal   (Followers: 3)
Mathematical Physics, Analysis and Geometry     Hybrid Journal   (Followers: 3)
Fundamental and Applied Limnology / Archiv für Hydrobiologie     Full-text available via subscription   (Followers: 3)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 3)
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen     Full-text available via subscription   (Followers: 3)
Geomagnetism and Aeronomy     Hybrid Journal   (Followers: 3)
Journal of Petroleum Science and Engineering     Hybrid Journal   (Followers: 3)
Journal of Marine Science and Technology     Hybrid Journal   (Followers: 3)
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften     Full-text available via subscription   (Followers: 3)
Stratigraphy and Geological Correlation     Full-text available via subscription   (Followers: 2)
Annales Henri Poincaré     Hybrid Journal   (Followers: 2)
Rocks & Minerals     Hybrid Journal   (Followers: 2)
Newsletters on Stratigraphy     Full-text available via subscription   (Followers: 2)
Polar Record     Hybrid Journal   (Followers: 2)
Mineralogy and Petrology     Hybrid Journal   (Followers: 2)
International Journal of Coal Geology     Hybrid Journal   (Followers: 2)
Helgoland Marine Research     Open Access   (Followers: 2)
Journal of Geophysics and Engineering     Hybrid Journal   (Followers: 2)
Izvestiya, Physics of the Solid Earth     Hybrid Journal   (Followers: 2)
Journal of Mining Science     Hybrid Journal   (Followers: 2)
Studia Geophysica et Geodaetica     Hybrid Journal   (Followers: 1)
The Leading Edge     Hybrid Journal   (Followers: 1)
Izvestiya, Atmospheric and Oceanic Physics     Full-text available via subscription   (Followers: 1)
Doklady Physics     Hybrid Journal   (Followers: 1)
Russian Physics Journal     Hybrid Journal   (Followers: 1)
Reports on Mathematical Physics     Full-text available via subscription   (Followers: 1)
Glass Physics and Chemistry     Hybrid Journal   (Followers: 1)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Neues Jahrbuch für Mineralogie - Abhandlungen     Full-text available via subscription   (Followers: 1)
Russian Journal of Pacific Geology     Hybrid Journal  
Russian Journal of Mathematical Physics     Full-text available via subscription  
Physics of Wave Phenomena     Hybrid Journal  
Moscow University Physics Bulletin     Hybrid Journal  
Moscow University Geology Bulletin     Hybrid Journal  
Marine Georesources & Geotechnology     Hybrid Journal  
Journal of Mountain Science     Hybrid Journal  
Grassland Science     Hybrid Journal  
Erwerbs-Obstbau     Hybrid Journal  
Bulletin of the Lebedev Physics Institute     Hybrid Journal  

        1 2 3 | Last

Similar Journals
Journal Cover
IEEE Journal of Oceanic Engineering
Journal Prestige (SJR): 0.697
Citation Impact (citeScore): 3
Number of Followers: 11  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0364-9059
Published by IEEE Homepage  [228 journals]
  • Excellence in Review 2021

    • Free pre-print version: Loading...

      Authors: Mandar Chitre;
      Pages: 268 - 270
      Abstract: Presents a listing of reviewers who contributed to this publication in 2021.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Multitask Cooperative Formation Control of Autonomous Surface Vehicles
           With Interception of Moving Objects

    • Free pre-print version: Loading...

      Authors: Xiaotong Cheng;Yu Lu;Lei Qiao;Zhihuan Hu;Weidong Zhang;
      Pages: 271 - 281
      Abstract: In this article, we present one solution to the multitask formation and moving objects interception problem of autonomous surface vehicles (ASVs) using the graph-based approach. The investigated problem includes three subtasks, i.e., to steer agents to a desired geometric pattern, to assign the ASVs for intercepting the moving attacker and forming a new formation, respectively, and to revert to original desired formation after successful interception. A switching strategy is designed to make the ASV switch between different modes. To deal with the nonlinear dynamics of ASV and improve the robustness against model uncertainties and external disturbances, the adaptive backstepping technique is incorporated. It is shown that the group of ASVs can accomplish all the tasks with different courses of attackers. The work offers a more flexible solution for the ASV group where malicious attacker exists. The effectiveness of the proposed approach is illustrated by simulations.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Measurement of Tidal Currents Using an Autonomous Underwater Vehicle

    • Free pre-print version: Loading...

      Authors: Anna Crawford;Jennifer Shore;Shiliang Shan;
      Pages: 282 - 294
      Abstract: Small autonomous underwater vehicles (AUVs) offer advantages in ease of deployment and recovery, covertness, and minimal logistical requirements for operation; however, speed and battery capacity can limit their effectiveness in areas where there are strong currents. While measurement of currents from these platforms is enabled by use of Doppler velocity logs (DVLs) with profiling capability, the quality of these current measurements needs evaluation. A trial was conducted in the Narrows channel of Halifax Harbour in October 2019 with coinciding tidal current measurements using fixed acoustic Doppler current profilers, drifters, and an AUV equipped with a profiling DVL. Output from a high-resolution tidal current model, Halifax Finite-Volume Community Ocean Model, has also been compared. The intercomparison of the current measurements and model output shows good agreement and highlights the complex structure of the tidal flow in the harbor channel. Evaluation of the AUV/DVL current measurements shows that adequate smoothing is achieved using shorter spatial/temporal averaging windows than other investigators have reported. A spatial (alongtrack) averaging bin size of 20 m, or equivalently 13 1-Hz profiles at 3-kn speed, reduces the standard deviation of the current magnitude measurements to a stable level. A shorter averaging scale allows fine enough detail in current mapping to be useful in harbor and littoral environments with strongly localized flows.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Takeoff and Landing Control of a Hybrid Aerial Underwater Vehicle on
           Disturbed Water’s Surface

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      Authors: Di Lu;Yinghao Guo;Chengke Xiong;Zheng Zeng;Lian Lian;
      Pages: 295 - 311
      Abstract: This article proposes a disturbance observer-based nonlinear control strategy for the accurate takeoff and landing control of a novel hybrid aerial underwater vehicle, Nezha III, subjected to wave and wind. The approach consists of the dynamic surface controller (DSC) and the nonlinear disturbance observers (NDOs). The problem is first modeled with full consideration of diverse external forces, including the capsizing buoyant moment, the added mass effect, and wave and wind loads. The DSC forms the base of the controller and benefits the tracking behavior by handling the nonlinearity of the system. Meanwhile, the integrated NDOs enhance the robustness of the closed-loop system by estimating the unmeasurable external forces. The proposed method is proved theoretically to stabilize the vehicle when it tracks the reference trajectory across different media in the presence of environmental disturbances. Finally, the proposed controller is tested numerically by challenging it under the wind and wave disturbances. The results show the controller makes Nezha III achieve successful takeoff and landing on the disturbed water’s surface in spite of the hazardous environment, which strongly evidence the outstanding performance of the proposed method.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Unsupervised Domain Transfer for Task Automation in Unmanned Underwater
           Vehicle Intervention Operations

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      Authors: Albert Sans-Muntadas;Martin B. Skaldebø;Mikkel Cornelius Nielsen;Ingrid Schjølberg;
      Pages: 312 - 321
      Abstract: During underwater intervention and monitoring operations, large amounts of imagery and sensory data are produced and stored. Moreover, these data might have the potential to help automatize future operations. In this article, we propose a method for producing segmented data that can be utilized in training of neural networks used for performing desired control tasks. By combining unlabeled images from previous operations with a paired 3-D drawing of the same monitored object, we can train a generative adversarial network to learn the domain adaption between two domains and produce synthetic images with a high resemblance to the original footage. The clear advantage is that the enhanced synthetic images contain the segmented information of the object without the expensive cost of manually segmenting the images. The enhanced segmented data are used to train an object detector that predicts bounding boxes locating the segmented object. This is used in two ways: 1) to analyze the quality of the segmentation and 2) to command a control task for a remotely operated vehicle relative to the object of interest. Controlling the yaw is the main control task to maintain the object centered in the camera frame. Additionally, we explore how overtraining of the domain adaptation network negatively impacts the accuracy of the object detector. This is done by comparing the accuracy of the object detector trained with the datasets produced by different epochs of the domain adaptation network.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Finding and Tracking a Phytoplankton Patch by a Long-Range Autonomous
           Underwater Vehicle

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      Authors: Yanwu Zhang;Michael A. Godin;Brian Kieft;Ben-Yair Raanan;John P. Ryan;Brett W. Hobson;
      Pages: 322 - 330
      Abstract: Phytoplankton (microscopic algae) play an important role in marine ecology. Resulting from a combination of physical, chemical, and biological processes, the distribution of phytoplankton is patchy, particularly in coastal marine ecosystems. Patches of high chlorophyll represent areas where enhanced primary productivity and biogeochemical cycling can occur. The scientific goal is to place observations within these biological hotspots to enable more extensive characterization of the environment and plankton populations. Aerial or satellite remote sensing can detect optical signal originating from phytoplankton within a limited depth range only near the ocean surface, and application of remote sensing is limited by atmospheric clarity. To observe the development of patchy phytoplankton communities in situ, we need the ability to locate and track individual patches. In this article, we present a method for an autonomous underwater vehicle (AUV) to autonomously find and climb on a positive horizontal gradient of chlorophyll to locate and track a phytoplankton patch. In two experiments in 2021, a Tethys-class long-range AUV autonomously located and tracked phytoplankton patches in southern Monterey Bay, CA, USA. The experiments demonstrated effectiveness of the method and pointed to the need for increased onboard adaptiveness in autonomous patch finding and tracking.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • A Methodology for Consistent Georegistration in Underwater Hyperspectral
           Imaging

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      Authors: Håvard Snefjellå Løvås;Aksel Alstad Mogstad;Asgeir J. Sørensen;Geir Johnsen;
      Pages: 331 - 349
      Abstract: This article proposes a novel methodology for precise georegistration in underwater hyperspectral imaging (UHI) using a red–green–blue (RGB) camera to build a photogrammetry model that estimates the pose and a 3-D seabed model. The two main scientific contributions are: 1) the development of two methods for geometric calibration of the hyperspectral imager (HSI) with the RGB camera and 2) the development of a methodology for consistent georegistration of the pushbroom hyperspectral imagery on the seabed using the photogrammetry model and the geometrically calibrated HSI. The georegistration uses a calibrated RGB camera, fixed to the HSI, with an overlapping field of view. The RGB images are used to build a photogrammetry model. Through utilizing the geometric HSI parameters from the calibration, the hyperspectral imagery is ray cast onto the 3-D model. This methodology is exemplified for UHI from a remotely operated vehicle on a cold-water coral reef in the Trondheim Fjord, Norway. The precision is unprecedented for georegistration in UHI, demonstrated by the first-ever spatially consistent UHI mosaic to contain multiple transects.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Assessment of Risks Induced by Countermining Unexploded Large-Charge
           Historical Ordnance in a Shallow Water Environment—Part I: Real Case
           Study

    • Free pre-print version: Loading...

      Authors: Nathalie Favretto-Cristini;Thierry Garlan;Olivier Morio;Xavier Demoulin;Michel Arrigoni;Anne Deschamps;Mickaël Bonnin;Éric Beucler;E. Diego Mercerat;David Ambrois;Romain Schwab;Paul Cristini;Fang Wang;
      Pages: 350 - 373
      Abstract: The goal of the work presented in a two-companion paper is to pave the way for reliably assessing the risks of damage to buildings on the shore, induced by the detonation of unexploded historical ordnance (UXO) of large weights in variable shallow water environments with a water depth less than 50 m. The risk assessment is quantified through the seismic magnitude on the Richter scale, induced by the detonation of charges of different weights (between 80- and 680-kg TNT-equivalent). This metric is investigated experimentally using a coupled seismo-acoustic approach within the framework of a UXO clearance (countermining) campaign in the Mediterranean Sea. Analysis of real acoustic and seismic data shows that, compared to a charge detonation in water, a similar detonation on the seabed generates seismic signals of lower frequencies and higher amplitudes that propagate in the seabed. The larger the charge weight, the higher the seismic amplitude. Besides the explosion-coast distance, the ground properties also affect the signals. The sediments favor a longer signal duration and the presence of late dispersive and very low-frequency signals with a large amplitude, whereas the rocky grounds better preserve the high-frequency energy propagation. For the local environment considered in this study, a charge detonation on the seafloor generates seismic events of higher magnitudes compared to a detonation in water. However, these magnitudes are likely low enough to prevent any large damage in the nearby inland infrastructures.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Assessment of Risks Induced by Countermining Unexploded Large-Charge
           Historical Ordnance in a Shallow Water Environment—Part II: Modeling of
           Seismo-Acoustic Wave Propagation

    • Free pre-print version: Loading...

      Authors: Nathalie Favretto-Cristini;Fang Wang;Paul Cristini;Thierry Garlan;Olivier Morio;E. Diego Mercerat;Vadim Monteiller;Anne Deschamps;Éric Beucler;
      Pages: 374 - 398
      Abstract: The goal of this work presented in a two-companion paper is to pave the way for reliably assessing the risks of damage to buildings on the shore, induced by the detonation of large-charge historical ordnance (i.e., countermining) in variable shallow water environments. Here, we focus on the impact of the marine environment, more specifically the unconsolidated sedimentary layer, on detonation-induced seismo-acoustic wave propagation. We rely on a multidisciplinary cross-study including real data obtained within the framework of a countermining campaign, and numerical simulations of the seismo-acoustic propagation using a spectral-element method. We first develop a strategy relying on physical insights into the different kind of waves that can propagate in a coastal environment, to provide clues for a computational cost reduction. The geological surveys and the hydroacoustic measurements provide input data for the 3-D axisymmetric modeling of wave propagation. The numerical simulations, obtained for one specific source–receiver path with a variable sedimentary facies, are compared with the real seismic data induced by the detonation of a charge either on the seabed, or in the water column, and recorded on the coast. Numerical analysis sheds light on the strong interaction between surface waves and the sedimentary facies. The short-scale and deep sedimentary basins favor a local wave-amplitude amplification and a frequency shift toward the low-frequency domain. However, the seismo-acoustic waves are globally attenuated during their propagation because of intrinsic attenuation and geometrical spreading, which generally prevents any large damage to nearby buildings on the shore.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Structural Imaging of Acoustic Survey Using a Deep-Towed Sub-Bottom
           Profiler and Hydrophone Cable

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      Authors: Masafumi Katou;Kenji Tara;Shutaro Saito;Ehsan Jamali Hondori;Kei Koshigoe;Eiichi Asakawa;
      Pages: 399 - 416
      Abstract: High-resolution images are required for the exploration of mineral resources on and beneath the deep seafloor. Under the Strategic Innovation Promotion Program launched by the Council for Science, Technology, and Innovation in Japan, we developed a survey system using a deep-towed acoustic source and receivers that produces very high-resolution subseafloor images. Our system uses a subbottom profiler as the acoustic source and a hydrophone cable as receivers. These instruments are towed near the seafloor by a remotely operated vehicle (ROV). The subbottom profiler generates chirp signals in the frequency band of 700–2250 Hz, and 32 hydrophones with a receiver interval of 1 m record the reflected waves. The system also includes two recorder units that record the acoustic wavefield with a sampling interval of 0.1 ms. We carried out field surveys at two locations in Japan: one site is in the Sea of Japan where gas hydrates were discovered and the other site is near Okinawa Island where a plume from a hydrothermal smoker was recorded by an ROV camera. Pre-stack depth migration was applied to the processed data using velocity models with a constant velocity gradient below the seafloor. The vertical resolution was 0.5–1 m depending on the depth, and the horizontal resolution was about ten times larger than the vertical resolution. The resulting images show that detailed subseafloor structures can be clearly imaged by the deep-towed system, even at sea depths greater than 1000 m.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Automatic Detection of Pipelines From Sub-bottom Profiler Sonar Images

    • Free pre-print version: Loading...

      Authors: Shaobo Li;Jianhu Zhao;Hongmei Zhang;YouPeng Zhang;
      Pages: 417 - 432
      Abstract: Sub-bottom profiler (SBP) measurements play a very important role in marine pipeline detection and checking. However, sometimes because of bad sea conditions and complex underwater environments, only poor SBP images can be obtained. Pipeline recognition based on a poor SBP image manually is tedious and has low accuracy. In this article, based on the specific hyperbola shapes caused by pipelines on SBP images, a novel method to detect the marine pipelines automatically and robustly is presented. Two main steps are used. First, a comprehensive edge extraction method is proposed, which includes line-like structure enhancement and preliminary edge extraction, local phase calculation and phase edge extraction, final edge extraction, as well as edge processing. By applying this method, interference such as reverberation can be eliminated, and fine hyperbola edges can be obtained. Second, by referencing the theoretical hyperbola and using a buffer zone and a hyperbola contour consistency (HCC) criterion, the location of the pipeline can be determined robustly. This method was implemented and verified using data collected under real conditions. The results show that the proposed method is practicable.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Multireceiver Synthetic Aperture Sonar Chirp Scaling Algorithm Considering
           Intrapulse Doppler Shift

    • Free pre-print version: Loading...

      Authors: Mengbo Ma;Jinsong Tang;Heping Zhong;Haoran Wu;
      Pages: 433 - 444
      Abstract: In synthetic aperture imaging, the interpulse Doppler shift is commonly used, while the intrapulse Doppler shift is ignored. However, for the linear frequency modulation signal, the intrapulse Doppler shift can cause an additional range cell migration (ARCM) and a phase error term. Additionally, the ARCM may exceed a range resolution cell in certain cases of multireceiver synthetic aperture sonar (SAS), which will result in image defocus. Therefore, the intrapulse Doppler shift in multireceiver SAS should not be ignored in such cases. In this study, the condition of the negligible intrapulse Doppler shift is presented, that is, the moving distance of the sonar platform within a pulse should be much less than an azimuth resolution cell. Based on the multireceiver accurate time-delay model, a multireceiver SAS intrapulse Doppler shift signal model is developed by introducing the intrapulse Doppler frequency into the echo signal. After simplifying the accurate range history under the narrow-beam assumption, the range-Doppler spectrum is derived. Finally, a multireceiver SAS chirp scaling algorithm considering the intrapulse Doppler shift (IDS-CSA) is derived. The proposed algorithm can correct the ARCM and compensate the phase error (although not required), and then obtain a well-focused synthetic aperture image. The effectiveness of the proposed model and algorithm is verified by simulations and field data. The results show that the proposed algorithm provides a better image quality than the conventional multireceiver CSA when the condition of the negligible intrapulse Doppler shift is not met.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Left–Right Ambiguity Resolution Methods for Closely Spaced Arrays

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      Authors: Baiju M Nair;Arun Kumar;Rajendar Bahl;
      Pages: 445 - 456
      Abstract: One linear array with omnidirectional sensors cannot discriminate between the azimuth angle and its complementary angle due to axisymmetry about the array axis. This article examines solutions to the bearing ambiguity problem known as left–right (LR) ambiguity resolution using two closely spaced parallel arrays. We design a second-order nulling (SoN) beamformer to produce a cardioid-type spatial response with a null electronically steered to the complementary angle of the direction of interest. Three methods—namely, SoN, null constrained beamformer (NCB), and 2-D direct beamformer (2-DDB), are studied. The performance is evaluated in correlated noise conditions modeled by a first-order auto-regressive process. This work establishes analytical results for the bound on the detection gain (DG) of the two parallel arrays in terms of the Rayleigh quotient of the circulant noise correlation matrix. A closed-form expression is developed for estimating the loss due to cardioid processing at closer inter-array spacing. The expressions are validated based on the deflection criterion. Twin-array processing using the 2-DDB method results in a higher DG, while cardioid-based beamformers give a higher rejection ratio (RR). Data from an at-sea experiment using a towed array are analyzed. Field results show that the deeper null achieved by the cardioid method results in a higher RR compared to 2-D direct beamformer. From the field data, approximately 19-dB LR discrimination is demonstrated at 1650 Hz for the broadside. Experimental results from a towed array corroborate theory and simulations.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Estimation of Synthetic Aperture Resolution by Measuring Point Scatterer
           Responses

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      Authors: David J. Pate;Daniel A. Cook;Brian N. O’Donnell;
      Pages: 457 - 471
      Abstract: The actual image resolution achieved by synthetic aperture systems often differs from the theoretical performance, and it is advantageous to automatically measure the realized resolution of these image products to monitor their quality. This article describes a novel image processing algorithm for measuring resolution based on the detection of prominent point scatterers. The algorithm proceeds in the following three main steps. 1) Identify candidate point scatterers via connected-component labeling and dual thresholding. 2) Prune the candidate scatterers and measure the size of the accepted detections by fitting an ellipse to the half-power contour traced in an oversampled image snippet. 3) Calculate the mode of the ellipse semiaxes lengths from a collection of scatterers to represent the local resolution estimate. The fitting of an ellipse to the half-power contour is a new contribution to resolution estimation that facilitates both detection and measurement, and it provides estimates of resolution in any direction, instead of only the range and along-track directions, which is important for images with excessive sensor motion. The accuracy and robustness of the algorithm are tested by applying it to simulated imagery with a series of parameter sweeps. Finally, the algorithm is applied to collected synthetic aperture sonar data and shown to be insensitive to seafloor textures.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Development and Experimental Validation of Endfire Synthetic Aperture
           Sonar for Sediment Acoustics Studies

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      Authors: Shannon-Morgan Steele;Anthony P. Lyons;
      Pages: 472 - 482
      Abstract: Seafloor sediment acoustic returns are comprised of scattering from both the sediment-water interface and the sediment volume. For low frequencies, volume scattering is often the dominant mechanism; however, direct measurements of this component have rarely been made, owing to the large beamwidths typically associated with low-frequency echosounder systems. When beamwidths are large, the sediment interface and volume returns arrive at the same time, causing estimates of volume scattering to become biased by the interface scattering. Endfire synthetic aperture sonar (EF-SAS) can achieve narrower beamwidths by coherently combining multiple acoustic returns as a vertically oriented transmitter and/or receiver is moved toward the seafloor. This article will present a proof of concept for EF-SAS, which will include an analysis of EF-SAS processing methods and an experimental verification of EF-SAS beamwidth improvements. Results from a motion-controlled EF-SAS experiment indicate that EF-SAS gains can be accurately predicted and that these gains are significant enough to remove the interface scattering bias.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Cross-Medium Communication Combining Acoustic Wave and Millimeter Wave:
           Theoretical Channel Model and Experiments

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      Authors: Fengzhong Qu;Jingyu Qian;Jie Wang;Xuesong Lu;Minhao Zhang;Xuerui Bai;Zhouhua Ran;Xingbin Tu;Zubin Liu;Yan Wei;
      Pages: 483 - 492
      Abstract: Communication across the water–air interface is an open research problem. A common solution is to place a relay on the water–air interface, which transmits received underwater acoustic signals to shore via electromagnetic waves. However, this solution has limitations, such as surface relays easily floating away or underwater relays becoming resource-intensive due to frequent surfacing, which make water–air communications unstable and costly. In this article, we investigate a recently proposed cross-medium communication technique, translational acoustic radio frequency (TARF) communications, in which underwater nodes can directly communicate with airborne nodes via acoustic waves and millimeter waves. For the first time, we introduce a closed-form, end-to-end channel and present its experimental validation. The high-frequency TARF communication is achievable with a frequency of up to 4.4 kHz. In the experiment deployment, underwater acoustic signals traveled as pressure waves, which produced water surface waves when they impinged on the water–air boundary. Airborne radar was employed to measure and decode these water surface waves. Experimental results and theoretical analysis demonstrated that 1) the cross-medium communication channel is frequency selective and time invariant; 2) cross-medium communications with both single-carrier and multicarrier signals are feasible; and 3) high-frequency signals from 3.6 to 4.4 kHz can be detected, which was considered difficult previously. This study provides a theoretical and experimental basis for achieving cross-medium communications between deep-sea moving objects, such as autonomous underwater vehicles and airborne nodes.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • 2021 List of Reviewers

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      Pages: 493 - 495
      Abstract: Presents a listing of reviewers who contributed to this publication in 2021.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
  • Special Issue on Underwater Communications and Networking 2021 (UComms21)

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      Pages: 496 - 496
      Abstract: Describes the above-named upcoming special issue or section. May include topics to be covered or calls for papers.
      PubDate: April 2022
      Issue No: Vol. 47, No. 2 (2022)
       
 
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