Browsing NTNU Open by Author "Dong, Hefeng"
Now showing items 21-40 of 49
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A JANUS-Based Consensus Protocol for Parametric Modulation Schemes
Wengle, Emil; Potter, John; Varagnolo, Damiano; Dong, Hefeng (Chapter, 2022)JANUS, the first digital underwater acoustic communications standard, is robust to noise in low SNR situations, but offers very limited data rate. A primary use of JANUS is thus that of a first-contact language in underwater ... -
Measurements of underwater noise radiated by commercial ships at a cabled ocean observatory
Zhang, Guosong; Forland, Tonje Nesse; Johnsen, Espen; Pedersen, Geir; Dong, Hefeng (Peer reviewed; Journal article, 2020)Measurements of underwater noise radiated under ship normal operations are presented. The acoustic data, from the cabled ocean observatory, are analyzed under each identified ship passage, which was obtained by the Automatic ... -
Mid-frequency sound propagation under a rough sea-ice cover
Isachsen, Lina Thu (Master thesis, 2021)I denne masteravhandlingen studeres forplantning av lyd i sjøvann under en isflate, med formål om kommunikasjon under is. Dette kan anvendes til navigasjon under is, klimaovervåking og havmodellering. For å adressere dette ... -
Modelling and study of seismic airgun generated wave-field related to zooplankton survival
Lyngstad, Arvid (Master thesis, 2021)Det er gjort flere studier om virkningen av menneskeskapt støy på marint liv, men de fleste omhandler virveldyr og større marine dyr. Innvirkningen på mindre livsformer som zooplankton har ikke blitt forsket på i like stor ... -
Modelling of Wave Propagation in Shallow Water Environment
Andersson, Skjalg (Master thesis, 2008)PlaneRay, an acoustic underwater propagation model based on ray tracing and plane- wave reection coecients, has been used to model wave propagation in shallow water environments. The program has emulated a seismic vessel ... -
Multi-frequency backscattering from the sea floor; can the frequency response be used to identify typical sandeel grounds?
Baisgård, Martin (Master thesis, 2008)In this report a phenomenological characterization technique of received bottom echoes has been developed and studied, to evaluate the potential of locating typical sandeel grounds. Data from a calibrated multi--frequency ... -
Next generation geophysical sensing: exploring a new wave of geophysical technologies for the energy transition
Ringrose, Philip; Landrø, Martin; Potter, John; Eidsvik, Jo; Wienecke, Susann; Bouffaut, Léa; Oye, Volker; Dong, Hefeng; Elster, Anne C.; Johansen, Ståle Emil (Peer reviewed; Journal article, 2021) -
Numerical study of the effect of cement defects on flexural-wave logging
Song, Ruolong; Dong, Hefeng; Bao, Xueshan (Journal article; Peer reviewed, 2019)Cement-bond evaluation is needed for new wells and plug and abandonment activities. The ultrasonic leaky Lamb-wave (also called the flexural-wave) technique, in combination with the pulse-echo technique, has been widely ... -
Physics-based characterization of soft marine sediments using vector sensors
Godin, Oleg A.; Deal, Thomas J.; Dong, Hefeng (Peer reviewed; Journal article, 2021)In a 2007 experiment conducted in the northern North Sea, observations of a low-frequency seismo-acoustic wave field with a linear horizontal array of vector sensors located on the seafloor revealed a strong, narrow peak ... -
Position Sensor for Dampers in FSAE Racing Cars
Livermore, Evelyn (Master thesis, 2012)EMATs are increasingly applied for NDT purposes in harsh environments because of their high resistance to temperature changes and shocks when compared with traditional piezoelectric transducers which require couplants. ... -
Quick clay monitoring using distributed acoustic sensing: A case study from Rissa, Norway
Rørstadbotnen, Robin Andre; Dong, Hefeng; Landrø, Martin; Duffaut, Kenneth; Growe, Kevin; Kakhkhorov, Umedzhon; Wienecke, Susann; Jacobsen, Joacim (Peer reviewed; Journal article, 2023)Quick clay avalanche is one of the most devastating landslide types worldwide. Hence, an early warning system is in demand to mitigate the fatal consequences caused by such events. To address this, distributed acoustic ... -
Self-supervised Underwater Source Localization based on Contrastive Predictive Coding
Zhu, Xiaoyu; Dong, Hefeng; Salvo Rossi, Pierluigi; Landrø, Martin (Peer reviewed; Journal article, 2021)This work introduces a two-step self-supervised learning scheme, namely contrastive predictive coding (CPC), for underwater source localization. In the first step, a CPC-based self-supervised feature extractor is trained ... -
Sensor Array Signal Processing for Source Localization
Manzano García-Muñoz, Cristina (Master thesis, 2008)This work is a study about source localization methods, more precisely, about beamforming approaches. The necessary background theory is provided first, and then, further developed to explain the basis of each approach. ... -
Shear Wave Velocity Estimation Based on Deep-Q Network
Zhu, Xiaoyu; Dong, Hefeng (Peer reviewed; Journal article, 2022)Geoacoustic inversion is important for seabed geotechnical applications. It can be formulated as a problem that seeks an optimal solution in a high-dimensional parameter space. The conventional inversion approach exploits ... -
Shear-Wave Tomography Using Ocean Ambient Noise with Interference
Wu, Guoli; Dong, Hefeng; Ke, Ganpan; Song, Junqiang (Peer reviewed; Journal article, 2020)Ambient noise carries abundant subsurface structure information and attracts ever-increasing attention in the past decades. However, there are lots of interference factors in the ambient noise in the real world, making the ... -
Ship track estimation from single hydrophone data
Larsen, Magnus (Master thesis, 2014)Passive acoustic range estimation and source tracking using hydrophones have been a problem because of the complexity of the underwater channel. This thesis is concerned with a fast method for the estimation of ship velocity ... -
Source localization in the ocean via machine learning
Iversen, Simon Andre (Master thesis, 2018)This study investigated source localization in the ocean using machine learning meth-ods. By interpreting the sound waves emitted by the source, localization can be acquired.In order to interpret the pressure, the machine ... -
Source Range Estimation in the Ocean using Time Difference of Multipath Arrivals
Skurtveit, Narve Garshol (Master thesis, 2016)Passive acoustic ranging in the underwater channel is a challenging task. It has been studied and used in military applications such as passive sonar, but also by marine biologists for mammal detection and ranging. Effective ... -
Study and Implementation of the Finite Difference Method for Wave Propagation in Fluid and Elastic Media
Moen, Inger Helene (Master thesis, 2006)Two finite-difference methods for calculating wave propagation in two-dimensional fluid and elastic media has been implemented. The first is developed from the second order wave equations, while the other stems from a first ... -
Study of Optimization Algorithms for Underwater Acoustic Applications
Skyberg, Niklas Saxlund (Master thesis, 2013)This thesis introduces the algorithms harmony search (HS) and artificial bee colony (ABC) to the field of geoacoustic inversion. HS mimics jazz musicians search of an optimal harmony through improvisation, while ABC is ...