TUESDAY 27 JUNE

0900
 
Introduction and welcome from the Conference Chairman
Romina Gehrmann, Research Fellow, University of Southampton, UK
 
Track One
PLENARY SESSION

SESSION CHAIR: Romina Gehrmann, Research Fellow, University of Southampton, UK

0915
 
KEYNOTE: Marine electromagnetic methods in exploration geophysics
Lucy MacGregor, Chief Scientific Officer, Rock Solid Images, USA
 
0945
 
KEYNOTE: An introduction to maritime electromagnetic signatures and sensing
Geoff Garnett, Technical Fellow, Platform Systems, Dstl, UK
 
1015
 
KEYNOTE: Exploration of the oceans using electromagnetic methods – from telegraphs to interstellar applications
Peter Sigray, Professor, Swedish Defence Research Agency, FOI, Sweden
 
1045
 
POSTER HIGHLIGHTS – 2 minute overviews by the poster presenters
 
1100
 
COFFEE BREAK: visit exhibitors and posters
 
Track One
SESSION 1: Electromagnetic Surveillance and Communication Systems

SESSION CHAIR: Brad Nelson, President, Aeromagnetic Solutions Inc, Canada

1145
+
Electromagnetic noise model extended to high geomagnetic activity and coastal areas
Lisa Rosenqvist, Scientist, Swedish Defence Research Agency, FOI, Sweden

Abstract:
We present the recent development of a global model of the electromagnetic background noise. The previous model which was valid only for low geomagnetic activity periods has been updated with an empirical model of ground-level geomagnetic perturbations valid also for high geomagnetic periods in the northern hemisphere. The linear relationship between the spectral slope and the level of geomagnetic activity, or KP index, is further investigated for different activity periods of the solar cycle and a range of latitudes. The modelled magnetic spectrum as well as knowledge of the electrical conductivity profile in the Earth’s crust further permits determination of the electric wave power spectrum. The model is validated with experimental electromagnetic data and can successfully predict the mean spectral levels for different latitudes and different geomagnetic activity.  However, near ocean-land interfaces electromagnetic fields are distorted by the conductivity of the nearby sea water. A simplified 2-D model has been used to investigate the magnitude and range of the effect for different polarization of the incident magnetic field. Also, the dependency on frequency, ground- and water conductivity, ocean depth and the slope of the bottom has been investigated. It is found that the electric field can be enhanced or suppressed by more than a factor 10 close to the coast depending on frequency, incident magnetic field polarization and ground conductivity. Thus, it is necessary to account for these effects in predicting noise levels in coastal areas.

Biography:
Dr. Lisa Rosenqvist received her PhD in 2008 in Space and Plasma Physics at Uppsala University in Sweden. Prior to her PhD Dr. Rosenqvist worked as a trainee at the European Space Agency. Since 2009 she is employed at the Swedish Defence Research Agency (FOI) as a research scientist in marine electromagnetics specialising in underwater electromagnetic applications such as noise modelling, induced electric fields, inverse techniques for environmental assessment, and mine logic modelling.

 
1210
+
Electric field sensing for airborne magnetic noise mitigation
Gregory Schultz, Chief Technology Officer, White River Technologies, USA

Abstract:
Current magnetic sensing systems, such as the latest versions of miniaturized atomic magnetometers, are capable of the highest sensitivities for ground, submerged, and airborne measurements.  The implementation of these sensors on modern aircraft (both  manned and unmanned aerial platforms) presents a number of challenges related to integration on various airframes, motion compensation, and mitigation of environmental and system noise.  In particular, we investigate the use of a miniaturized high-sensitivity electric field sensor to aid in compensating for magnetic noise emanating from space, atmospheric, and on-board sources.  We found through quantitative analysis of co-located and synchronized E- and B-field data from international magnetic observatories and our own experimental data collections that correlations between the orthogonal components of E- and B-fields are dependent on the source/type, amplitude, and frequency of signals.  We have developed a detection-level approach that supports the physics involved in E-field and B-field sensing of subsea targets from an aerial platform.  We also utilized data analysis to develop geoatmospheric and magnetotelluric models that represent the correlation between E- and B-fields. We present research and sensor developments over the past 1.5 years that include: 1) implementation of detection level approaches to geoatmospheric noise induced false alarm rejection that mitigate the potential pitfalls of direct E-to-B correlation and subsequent coherent noise signal subtraction and 2) development and testing of a simple,  robust, and compact electrostatic field mill technology that is tailored for naval unmanned airborne applications.

Biography:
Dr. Schultz is currently the Chief Technology Officer at White River Technologies.  He has been conducting research and development of geophysical sensor systems for over 15 years with focus on implementation and deployment of magnetic and electromagnetic/RF sensor arrays from unmanned platforms.  He has been the principal investigator for a number of US Defense sponsored applied R&D projects for detecting, characterizing, and marine threats – especially moving targets and explosive hazards.  Among his current research interests are the development of innovative configurations of miniaturized magnetic sensor systems such as new chips-scale atomic magnetometers and compact multi-axis EMI and RF sensors.

 
1235
 
LUNCH BREAK
 
Track One
SESSION 2: Seafloor and Sub-Bottom Electromagnetic Exploration

SESSION CHAIR: Romina Gehrmann, Research Fellow, University of Southampton, UK

1350
+
The next generation CSEM acquisition system
Peter Hanssen, Lead Geophysicist, Statoil ASA, Norway

Abstract:
Since the first survey in 2000, the Controlled-Source Electro-Magnetic (CSEM) method has seen considerable development and is now an established tool for hydrocarbon exploration. Unfortunately, the penetration depth is limited for marine CSEM and the exponential decay makes the electromagnetic signal insensitive to deeply buried stratigraphy, including thin resistive layers, since the signals from these deep structures may be buried in the ambient noise. To overcome this limitation of the CSEM technology, EMGS, Shell and Statoil have executed a Joint-Industry Project with the purpose of constructing a next generation acquisition system.  The target was to increase the source dipole strength by a factor of 10 and also the receiver sensitivity by a factor of 10, measured from the 2011 state-of-the-art. With an increase of a factor of 100 in signal-to-noise ratio, the maximum imaging depth can be expected to increase by approximately 2 km. A prototype system with a new source and 10 receivers was completed in July 2016 and successful field tests have been carried out. With much higher transmitter dipole moment and more sensitive receivers, the next generation system provides a step change improvement in the data quality, with clean data for all source frequencies out to 20 km offset compared to around 10 km offset for the reference system. The high data quality also provides clear improvements in the inversion results. We expect a maximal imaging depth, relative to the seabed, of up to 4500 m in future surveys with a commercial version of the system.

Biography:
Peter is a Lead Geophysicist at Statoil’s Research Centre in Bergen heading instrumentation and acquisition research for exploration. At the moment he works on new seismic sources and the Next Generation CSEM equipment. Previously he worked with broadband acquisition, simultaneous shooting, AUV-based gravity, contactless OBS, passive seismic, sub-basalt imaging, sub-salt imaging and arctic solutions.

He joint Norsk Hydro, now Statoil, in 2004 after working for the British Geological Survey in Edinburgh. He got a PhD in Geophysics from the University of Edinburgh and lectured ‘Applied Geophysics’ at the University of Glasgow. Before his time in Scotland he worked for the GeoForschungsZentrum Potsdam, Germany. Peter receiving his Master in Geophysics from the Technical University of Berlin working on Neural Networks.

 
1415
+
Large-scale 3D anisotropic inversion of towed streamer EM data using the Gauss-Newton method
Johan Mattsson, R&D Manager, PGS, Sweden

Abstract:
We present a newly developed 3D inversion code for Towed streamer EM data utilizing the Gauss-Newton method. The code is designed and implemented on a standard cluster of nodes to handle large-scale inversions of the order 25 million unknowns. The corresponding Jacobian matrix of about 2 Tb is split over the subscribed computational nodes and processes in order reduce the memory consumption on each node as well as to reduce the computational time. This enables the use of the full Gauss-Newton method on this amount of data. The forward modeling part is based on a parallelized integral equation formulation of the electric field. The forward and inversion grids cover the entire survey area including bathymetry and down to 5 km below sea surface. The performance is demonstrated with an unconstrained anisotropic 3D inversion on Towed Steamer EM data over a survey area covering a total of 5206 sq. km, acquired in the Barents Sea in 2014. The survey consisted of 38 parallel acquisition lines with a spacing of 1.25 km and an average length of 115 km. The number of data observations was 505820 with a total of 6 frequencies in the range from 0.2 to 2.2 Hz, 7226 shot points and 16 receiver offsets. The inversion grid consisted of 13 million cells and extended from the water column down to 5 km below the sea surface. The inversion ran 14 Gauss-Newton iterations and converged at a misfit of 3.7% at a geologically feasible anisotropic resistivity model.

Biography:
Johan Mattsson is currently head of the Towed Streamer EM R&D in Petroleum Geo-Services (PGS). He earned a PhD in engineering mechanics in 1996 from Chalmers University of Technology, Sweden. Dr. Mattsson has primarily worked with forward and inverse modeling in the areas of elastodynamics, ocean acoustics and marine electromagnetics.

 
1440
+
A new type of marine Controlled-Source Electromagnetic transmitter and receivers
Yuguo Li, Professor, Key Laboratory of Submarine Geosciences and Prospecting Techniques of Ministry of Education, Ocean University of China, China

Abstract:
This presentation will report on advances in marine controlled-source electromagnetic (MCSEM) research at the Marine EM laboratory at Ocean University of China. A new type of broadband Ocean-Bottom ElectroMagnetic (OBEM) receiver has been recently developed at OUC. The OBEM receiver is an autonomous seafloor data logging system and is designed to measure both the magnetotelluric signal and the controlled-source electromagnetic signal on the seafloor. The OBEM receiver collects three components of the electrical field and two horizontal components of the magnetic field. A CTD unit with the compact compass is mounted on the top of the non-magnetic frame.  These OBEM receivers concluded their 1000- and 4000-meter deep sea trials in the South China Sea last year. Wehave seen more than 40 deployments with 100% recovery rate. We also have developed a new transmitter for the marine CSEM sounding.  It can deliver up to 1000A current into a neutrally buoyant antenna of 200m long. It was deep-towed at the end of a cable containing three optical fibers that is used to power the transmitter and for telemetry between the deep-towed transmitter and the shipboard control console. It also hosts an altimeter to measure height above the seafloor and an ultra-short baseline acoustic transponder to locate the position of the transmitter. It also hosts a CTDV sensor to measure the seawater conductivity and velocity. The transmitter has been successfully tested in the Southern China Sea.

Biography:
TBC

 
1505
+
Marine electromagnetic instrument development and experiments in the South China Sea
Ya Xu, Associate Professor, Institute of Geology & Geophysics, Chinese Academy of Sciences, China

Abstract: In recent years, we have developed the marine electromagnetic instruments with the micro-magnetic fluxgate sensor and Ag-AgCl electrodes in the Institute of geology and geophysics. At the first stage, the electric meter and magnetic meter were first developed for system testing and experiments. Then the combined system for electromagnetic survey was established for seafloor survey. We carried several experiments in the South China Sea (SCS) to verify the performance of the instruments and study the marine electromagnetic field. Four experiments have been done from 1000 to 3500 meter with the Ocean Bottom Electric meter (OBE) and the Ocean Bottom Magnetometer (OBM). The instruments work well mechanically and get the right signal at the sea floor. The magnetic field recorded in the northern SCS is similar like the signal recorded in the land station of Sanya. The spectrum analysis of the electric field recording also shows the characters of the sea floor electric field. The primary analysis of the recordings reveals good potential of the OBEM instruments for marine geology survey on deep structure.

Biography: 

Mr. Ya Xu is an Associate Professor of the Institute of geology and geophysics, Chinese Academy of Sciences.  His scientific research focuses on the marine geophysics research and integrated geophysical research. In recently years, he joined in the marine geophysical survey and research work based on OBS and OBEM in China with his colleagues.


 
1530
 
COFFEE BREAK: visit exhibitors and posters
 
Track One
SESSION 3: Vessel Electromagnetic Signature Prediction and Control

SESSION CHAIR: Owen Griffiths, Principal Engineer, Maritime Integrated Survivability, Dstl, UK

1615
+
Assessment and optimisation of field homogeneity in de-perm facilities
Christopher Riley, Engineering Manager, Cobham Technical Services, UK

Abstract:
De-perm facilities need a coil system that will provide a uniform magnetic field within the vessel that is being de-permed. As the topology of the vessel is variable – surface and submersible vessels are very different, a reasonable starting point is to produce a uniform dipole field in free space. De-perm in the longitudinal direction requires that the aspect ratio of the homogeneous field region is quite large. Techniques used to assess the homogeneity in approximately cubic volumes must be adapted.

In this paper, the authors review various options for assessing homogeneity. One possibility is sampling at a set of discrete points to calculate mean value, standard deviation, maximum and minimum of the field. Options for choosing the sampling points are investigated. The other possibility is to express the field using coefficients of an orthogonal series, such as a Fourier series or Associated Legendre Polynomials. This option is viable because the solution to Laplace’s equation within an interior volume is completely defined by expressions using the harmonics evaluated at the exterior surface and the coordinates. Reducing the higher order harmonic coefficients (above the dipole) implies that the field is more homogeneous. Such methods are used regularly for assessment of field quality in other applications such as MRI and particle accelerator magnets. To assess the effectiveness of the methods, each is subjected to a Pareto optimisation to determine an optimum 9-coil longitudinal de-perm system design, which is then used in a de-perming simulation for a simple example model.

Biography:

B.Sc.(Eng) in Electrical Engineering, UCL, 1975; C.Eng., MIEE, 1986; FIEE (now IET), 2001; 1971 – 1981 GEC Power Engineering

Sandwich scheme student/graduate apprentice, assistant development engineer, technologist in electromagnetics laboratory. Specializing in electromagnetic finite element software after graduation. 1981 – 1984 Compeda Ltd./Prime CADCAM Ltd.

Support /senior support/consultant engineer in electromagnetic design software.

1984 – 1986 Dept of Electrical Eng., Liverpool University, Lecturer in CAD and electromechanics. 1986 – 1992 Vector Fields Ltd – Support and development engineer for electromagnetic design software. Support and Applications Manager.

1992 – 1995 Vector Fields Inc. VP responsible for North American sales, support and consulting. 1995 – Present day Vector Fields Ltd./Cobham Technical Services

Director of projects/Engineering manager. Overall responsibility for obtaining and management of collaborative projects, and support / application activities. Member strategic management team. Part-time engineering consultant since October 2015.

Publications – Author of more than 70 papers and technical articles

 
1640
+
Decomposition of ferromagnetic signature with respect to induced and permanent magnetization
Jan-Ove Hall, Senior Scientist, Swedish Defence Research Agency, FOI, Sweden

Abstract:
An algorithm for decomposition of the ferromagnetic signature into components due to permanent and induced magnetization, is presented. The decomposition is instrumental for the calibration of degaussing systems at magnetic ranges. A source model is formulated for describing the signature. The model consist of two collections of magnetic dipoles, representing the permanent and induced magnetization. The induced part of the source model depend on the heading of the ship relative to the Earth’s magnetic field. A general linear relation between the induced moment and the external magnetic field is assumed. The parameters of the model are determined by formulating and solving a regularized inverse problem using magnetic field data from multiple passages of the ship over the sensor lines.  Data from at least three passages with different headings are co-processed to obtain an estimate of the model parameters.  The analysis is entirely based on data from magnetic ranges and does not rely on numerical modelling of the induced field. We demonstrate how to apply the algorithm with an example using data from a mobile magnetic range. The mobile range consist of a single sensor line with three-axial magnetometers. A surface ship is modeled by using a simplified geometry and magnetization state. The data is synthetically generated by calculating the magnetic signature using a finite element (FEM) solver.  Field maps of the permanent and induced fields are calculated using the resulting source model.

Biography:
Dr. Jan-Ove Hall received his PhD in 2004 in Space and Plasma Physics at Uppsala University. Before joining the Swedish Defence Research Agency (FOI) in 2006, he had a post-doc position at the department for theoretical physics at Ruhr-University Bochum. His research at FOI is focused on problem related to electric and magnetic ship signatures.

 
1730
 
End of Day 1
 
17.30 - 19.00
 
Drinks Reception – Victoria Gallery & Museum, Ashton St, Liverpool L69 3DR
 

WEDNESDAY 28 JUNE

0830
 
Morning Refreshments
 
Track One
SESSION 4: Electromagnetic Surveillance & Communication Systems

SESSION CHAIR: Greg Schultz, Chief Technology Officer, White River Technologies, USA

0900
+
Results from an underwater electromagnetic communication trial using QPSK waveforms
Tom Braute, Senior Scientist, Norwegian Defence Research Establishment (FFI), Norway

Abstract:
Electromagnetic (EM) waves can be beneficial for underwater wireless communication in situations where acoustic waves yield poor performance due to special underwater environments. An interesting case is when the EM source and receiver are located close to the seabed utilizing the seabed communication path. This path, which is caused by propagation of EM lateral waves, has less attenuation than the direct- and reflected paths through sea water.  Previously, we have studied the seabed communication path using frequencies up to 1 kHz, which limits the data rate, but enables data link ranges of kilometres. To examine higher data rates we have conducted underwater EM communication trials utilizing the frequency range 1 – 19 kHz, which however reduces the attainable data link range. The trials comprised a pair of horizontal magnetic loop transmitting- and receiving antennas, emplaced on the seabed and separated by 70 m. This paper presents results obtained from testing quadrature phase-shift keying (QPSK) waveforms at different centre frequencies and bandwidths. We observed the measured bit error rate (BER) versus signal-to-noise ratio (SNR) resembles the theoretical BER curve for the additive white Gaussian noise (AWGN) channel. When combining measurements and analytical formulas for EM lateral wave propagation, it was possible to simulate an arbitrary seabed communication path. Simulations show that seabed conductivity affects which centre frequency should be chosen for error free communication when a minimum magnetic moment is required. For low and high seabed conductivity situations the favourable centre frequency is in the upper and lower frequency range, respectively.

Biography:
Tom Braute is a senior scientist at the Norwegian Defence Research Establishment (FFI). His work has been performed in the mine countermeasures group at the maritime systems department. He received his M. Sc. from the Norwegian University of Science and Technology, Department of Electronics and Telecommunications in 1994.

 

 
0925
+
Underwater to Air Magnetic communication link budget
Boris Ginzburg, Senior Researcher, NRC Soreq, Israel

Abstract:
Magnetic communication link with frequencies in the ultra-low-frequency (ULF) band features good penetration ability even through salted sea water. ULF signals with frequencies in the range of 0.3 – 3 kHz feature skin effect depth values of about 4 – 13 m for sea water, and data rates range from several to hundreds bits per second. Thus, the ULF band seems as a reasonable tradeoff between penetration ability and data rate.  In previous work, we investigated land-to-underwater and air-to-underwater magnetic communication down-links. In the present work, we focus on the underwater-to-air communication up-link. This communication segment is important for ‘closing the loop’. For example, consider an underwater sea-bed sensor collecting environmental data. In some cases, we would like to keep it hibernated, waiting to be triggered. A magnetic trigger signal can be generated by an aircraft equipped with a magnetic transmitter, as discussed in previous work. It is important to have unambiguous indication that the sensor is alive and has been actually triggered. Such indication may be provided by a magnetic underwater-to-air up-link. This magnetic signal is rather difficult to detect and jam from a distance. In contrast to acoustic waves, the magnetic signal is not blocked by underwater terrain and does not suffer from interference due to surf-zone reflections. In the present work, we model this communication up-link channel. We also estimate the link’s budget, considering receiver sensitivity, transmitter magnetic moment, and channel attenuation. The attenuation is calculated using a computer model including seabed-water and air-water interfaces.

Biography:
Dr. Boris Ginzburg is a research physicist with the SOREQ Nuclear Research Center. He earned his M.Sc. in radio-physics & electronics from the Technical University of St.-Petersburg (Russia). He obtained his Ph.D. in physics & mathematics from Phys.-Techn. Ioffe Institute, St.-Petersburg (Russia). In the years 1974-1996 he served as research scientist at Geophysical Research Institute in St.-Petersburg. From 1997 he was with the Geological Survey of Israel (GSI) where he was involved in investigation of tectonomagnetic effects. From 2000 he is with SOREQ NRC and takes part in projects related to precise magnetic measurements. Dr. Ginzburg is the Head of research group; his main scientific interests are in the field of precise measurements of the Earth’s magnetic field and various magnetic search & detection applications.

 

 
0950
+
Range extension for electromagnetic detection of power and telecommunication cables
Tomasz Szyrowski, Academic, Plymouth University, UK

Abstract:
Subsea cables play an important role in social and economic life. Connections made between continents, island, and offshore installations require constant attention, periodic maintenance and repairs. The most vulnerable parts located in shallow water are often protected by placing the cable a few metres under the ocean floor. Although the cables are buried in the seabed, the dynamic marine environment often causes changes in cables initial location. Buried cables are difficult to localise and survey. From all possible techniques only electromagnetic (EM) methods can penetrate the seabed without loss of resolution and provide reliable means of thin cables localisation.

The EM methods suffer their own limitations. The EM waves attenuate faster in conductive media such as sea water. For this reason the EM localisation is seen as a short range detection requiring use of autonomous or remotely operated underwater platforms.

To minimise the costs of the cable survey operations, new methods of localisation were developed.  The batch particle filter for localisation greatly extends the range of detection. The underwater utilities can be surveyed from the boat in waters exceeding 20 metres depth. Although the method provides very good means of fast acquisition, reliable cables surveying, it might be affected by sea conditions and prone to wave induced motion noise.

To avoid those problems the extensions of the method were investigated. The paper presents developments in EM detection and provides comparison of magnetic, electric, tone induction and self-generated frequencies in power and telecommunication cables.

Biography:
Tomasz Szyrowski is an engineer, scientist and researcher closely working with industry and academic partners. After years spend within a business he came back to University pursuing his diploma in Mathematics and Statistics leading to research based PhD in Marine Engineering. In the last years he worked on problems related subsea cable tracking. As part of his academic work he developed novel algorithms for cable localisation. He successfully applied his knowledge among industry during projects of cable surveys, landings and repairs in Europe and South America.

 
1015
 
POSTER HIGHLIGHTS – 2 minute overviews by the poster presenters
 
1030
 
COFFEE BREAK: visit exhibitors and posters
 
Track One
SESSION 5: Vessel Electromagnetic Signature Prediction and Control

SESSION CHAIR: Alastair Ballentine, Product Manager Submarine Systems, Atlas Elektronik, UK

1115
+
Magnetic signature identification using pareto optimization
Christopher Riley, Engineering Manager, Cobham Technical Services, UK

Abstract:
Determining the topology of a naval vessel from its measured magnetic signature is a classic inverse problem – what is the source of the observed response? Pareto optimization has been successfully used in other applications to determine size and position of buried objects, such as oil and gas pipelines.  In this paper, the same technique is applied to measured* signatures (as would typically be obtained from a range). When the topology of the source is known (a hollow steel tube with hemispherical end caps, represented using a 2D thin-plate surface in the Opera software), two of the three optimization variables – length and outer radius – are predicted very accurately, while the third – thickness of steel – is less accurate. This example also shows the benefit of using objective functions that are based on integrations of the measured signature, rather than values of field at a set of discrete points. In the second part of the presentation, unknown topologies are also examined. Several possible simple models which can be described using a small set of variables (including a hollow ellipsoid, a set of hollow spheres, and two hollow triangular prisms) are used to predict the major dimensions of both a measured submersible and surface vessel. The success (or otherwise) of each representation is reviewed. * In this paper, the ‘measured’ results are computer predictions from vessel models of known dimensions

Biography:
B.Sc.(Eng) in Electrical Engineering, UCL, 1975; C.Eng., MIEE, 1986; FIEE (now IET), 2001; 1971 – 1981 GEC Power Engineering

Sandwich scheme student/graduate apprentice, assistant development engineer, technologist in electromagnetics laboratory. Specializing in electromagnetic finite element software after graduation. 1981 – 1984 Compeda Ltd./Prime CADCAM Ltd.

Support /senior support/consultant engineer in electromagnetic design software.

1984 – 1986 Dept of Electrical Eng., Liverpool University, Lecturer in CAD and electromechanics. 1986 – 1992 Vector Fields Ltd – Support and development engineer for electromagnetic design software. Support and Applications Manager.

1992 – 1995 Vector Fields Inc. VP responsible for North American sales, support and consulting. 1995 – Present day Vector Fields Ltd./Cobham Technical Services, Director of projects/Engineering manager. Overall responsibility for obtaining and management of collaborative projects, and support / application activities. Member strategic management team. Part-time engineering consultant since October 2015.

Publications – Author of more than 70 papers and technical articles

 
1140
+
Demonstration of the TNO magnetic signature design tool
Eugene Lepelaars, Researcher, TNO, Netherlands

Abstract:
An advanced magnetic signature design tool for submarines has been developed by TNO. The tool, developed in Matlab, is capable of assessing the magnetic signature level at an arbitrary depth as a function of various design choices, including the overall submarine dimensions, the maximum diving depth, the steel type of the hull and the number of coils in the degaussing system. The input of the tool is a collection of more than 4000 FEM simulations using the software package Comsol Multiphysics, totaling several gigabyte of data. Special care was taken to make the tool as fast and flexible as possible, resulting in a calculation time on the order of 1 s for a single submarine configuration. Noteworthy is that the tool, besides calculating the effects on the magnetic signature, is also capable of quantifying the trade-off between achieving a given magnetic signature level on the one hand and the cost, power, weight and volume of the required degaussing system on the other hand. The magnetic signature design tool thus makes it possible for designers to take the magnetic signature of a new submarine into account in an early stage of the design process.

Biography:
TBC

 
1205
+
Electric signature prediction tool
Simon Topping, Head of CS Signatures Department, Atlas Elektronik, UK

Abstract:
This paper describes the formulation, development and testing of a rapid submarine magnetic signature prediction tool for use during design, mission planning and operational activities. The tool can be used to predict the change in a submarine’s static ferromagnetic signature due to operational effects including: location and heading change; but most notably also the change in a submarines permanent signature which can occur during a dive. This change is caused by the highly non-linear stress magnetisation effect which results in a change to the remnant magnetisation of the platform due to interaction between the stresses induced within steel structures (such as the pressure hull) during a dive and the Earth’s magnetic field. The novel modelling approach embedded within the tool uses a parameterisation of experimental data which is assimilated with full scale platform measurements. Verification of the model has been achieved by comparison of model output with data collected from model scale experiments. The tool can provide a near instantaneous prediction of the magnetic signature during an entire patrol. Proposed uses of the tool include: support to platform design (minimise or control signature change expected during platform patrols); prediction of platform susceptibility within potential forward operating areas based on current knowledge of the platforms signature (support pre-deployment planning); and provision of real-time signature advice to the platform crew during a patrol.

Biography:
After completing a PhD in marine geophysics Simon joined QinetiQ’s Under Water Division in 2003 which was later transitioned to ATLAS ELEKTRONIK UK (AEUK) in 2010. During his time with AEUK and its predecessor organisation, he has been heavily involved in understanding and modelling the generation, propagation and detection of the non-acoustic signatures of naval platforms. In 2013 he became head of the Signatures Department within AEUK, taking on responsibility for both acoustic and non-acoustic signature aspects.

 
1230
 
LUNCH BREAK
 
Track One
SESSION 6: Oceanographic Electromagnetics

SESSION CHAIR: Neil Stapleton, Principal Scientist, Dstl, UK

1345
+
Validation of models of EM fields induced by ocean swell using bottom mounted sensor systems
Brian Glover, Physicist, Naval Surface Warfare Center, Carderock Division, USA

Abstract:
The motion of conducting seawater through Earth’s magnetic field induces secondary electromagnetic fields.  Ocean waves, including internal waves and surface waves, produce electric and magnetic fields in this fashion.  We use dynamical pressure from an absolute pressure unit deployed in approximately 100 meters of water to estimate water column velocities for observed ocean swell.  These velocities serve as input to dynamical models for prediction of electric and magnetic fields due to observed swell.  The predicted fields are compared favorably to observed electric and magnetic fields, providing in-situ model validation of the models.

Biography:
Dr. Glover has worked at the Naval Surface Warfare Center, Carderock Division since 2009.  While at Carderock, Dr. Glover has studied underwater electromagnetic fields and their application to Naval technologies.  His interests include modeling of fields in maritime environments, EM sensing systems, environmental sources of EM fields, and signal processing.  Dr. Glover received his doctorate in Theoretical High Energy Physics from the College of William and Mary in 2009.

 
1410
+
Characterization of subsea electromagnetic fields using an AUV
Manhar Dhanak, Professor & Director, Florida Atlantic University, USA

Abstract:
Application of an autonomous underwater vehicle (AUV) for field measurement and characterization of electromagnetic fields in coastal waters is described. The electric field is measured using a custom 3-axes sensor mounted on a Bluefin 21 AUV and the magnetic field is measured using a Marine Magnetics SeaSPY magnetometer towed from the vehicle so that it is isolated from the AUV machinery. The AUV is equipped with onboard upward (600kHz) and downward (300kHz) looking acoustic Doppler current profilers (ADCPs), and a conductivity-temperature-depth (CTD) measurement package which simultaneously provide the contextual in-situ oceanographic information, including temperature, salinity, and current velocity in the water column. The electric-field sensor development, its implementation of the EM sensors on the AUV and their deployment in coastal waters is described in illustrative surveys of the water column aimed at characterizing EMF associated with various sources including internal waves in the water column and EMF a submerged cable with the power in the cable turned off/on.

Biography:
D
r. Manhar Dhanak is a Professor in ocean engineering at Florida Atlantic University and Director of the University’s Institute for Ocean and Systems Engineering (SeaTech). He has research interests in hydrodynamics, physical oceanography and marine magnetics, including applications of unmanned underwater vehicles to oceanography and marine sensing.

 

 
1435
+
Magnetic field variations induced by submesoscale processes in the shallow water ocean environment
Alexander Soloviev, Professor, Nova Southeastern University, USA

Abstract:
Podney’s (1975) model has traditionally been used for calculation of the magnetic signature of surface and internal waves. Preliminary results of an experiment at the SUrge STructure Atmosphere INteraction facility (Kluge et al. 2017) suggest that substantial contribution to the magnetic signature of surface waves may come from the difference in magnetic permeability of the air and water, which is not accounted for in the traditional model. Magnetic properties of the seafloor, depending on geological composition of substrata, can also affect the magnetic signature of oceanic processes in the shallow water environment (Smagin et al. 2014). A suite of hydrodynamic, magnetic, and remote sensing models for studying magnetic signatures of submesoscale ocean processes previously reported by Soloviev et al. (2013) has been upgraded with the ANSYS Maxwell model, which is capable of simulating magnetic permeability changes at the air-sea and bottom boundaries. We report the modeling results of magnetic signatures of surface and internal waves, coherent structures, surface-intensified and undercurrent jets, fronts, and freshwater lenses.

Biography:
Alexander Soloviev is a Professor of Physical Oceanography at Nova Southeastern University’s Halmos College of Natural Sciences and Oceanography, Dania Beach, Florida and an Adjunct Professor at the University of Miami, Miami, Florida. He participated in several major oceanographic experiments and is the author and co-author of more than 70 research articles published in peer-reviewed journals. In co-authorship with Prof. Roger Lukas (UH), he wrote a monograph “The Near-Surface Layer of the Ocean: Structure, Dynamics, and Applications” published by Springer. Alexander is a naturalized US citizen. He received his Diploma of Engineer and Ph.D. from Moscow Institute of Physics and Technology in 1976 and 1979, respectively. He also received his Habilitation degree from the former Soviet Academy of Sciences in 1992 and MBA from the University of Florida in 2010. Dr. Soloviev has been PI on a number of research projects funded by the US Federal Government and private industries.

 
Track One
SESSION 7: Electromagnetic Surveillance & Communication Systems

SESSION CHAIR: Owen Griffiths, Principal Engineer, Maritime Integrated Survivability, Dstl, UK

1545
+
Sensor body shape effects on electric field measurements
Carmen Lucas, Defence Scientist, DRDC Atlantic Research Centre, Canada

Abstract:
The measurement of electric fields in a conducting media, such as sea-water, is of interest and has applications in several areas of research, such as the corrosion sciences. Electric fields are usually measured using a pair of electrodes separated by a distance, and the estimate of the electric field is the negative voltage potential difference between the two electrodes divided by the distance. The electrodes are usually mounted on some non-conducting structure or surface, however, which can itself perturb the local potential field.  This results in a potential difference that is different from what would be measured in the absence of the structure and leads to an inaccurate estimate of the electric field.  An analytical investigation was performed to calculate this effect for pairs of electrodes mounted on the surface of non-conducting prolate and oblate spheroid shapes, with electrode pairs along the minor and major axes, in an infinite conducting media and uniform applied electric field. An ‘effective gain’ is calculated for the full range of minor to major axis ratios for both spheroid types, and applied field directions (longitudinal or transverse), with the limiting shapes of the spheroids being thin cylinders, spheres, and flat circular disks.

Biography:
Graduated University of British Columbia 1985, Bachelor of Applied Science in Engineering Physics, Electrical Engineering major.  1986-1999

Senior Scientific Programmer / Analyst, Barrodale Computing Services Ltd., Victoria BC, Canada; 1999-Present Defence Scientist, DRDC Atlantic Research Centre, Halifax Nova Scotia, Canada.

 
1610
+
Simulating the bias of high conducting system components on the sensitivity of marine FDEM sensors
Konstantin Reeck, PhD Student, University of Bremen, Germany

Abstract:
The electromagnetic deep-sea profiler ‘Golden Eye’ developed at the University of Bremen shows great potential to provide economic and environmental insights into structure, composition and spatial distribution of seafloor massive sulfide deposits. The design is based on a rigid, circular fiberglass platform that hosts a 3.4 m diameter horizontal, frequency domain EM in-loop sensor in a marine sensing infrastructure. This poster evaluates the bias of its highly conductive titanium pressure housings on the required sensitivity of the sensor for environmental mapping and inversion purposes and the efficiency of in-situ calibration methods to compensate those effects. The study has been performed in a newly developed and experimentally verified 3D Finite-Element model in COMSOL Multiphysics with the ability to quantify the effects by a suitable choice of boundary conditions at the seawater/metal interfaces. We investigate the perturbation of the pressure housings by the generated alternating magnetic fields in varying proximities to the sensor by simulating its full- and halfspace responses for range of natural occurring conductivities. The experiments show that a system calibration against (1) seawater conductivity measured by a CTD during diving, and (2) a remotely activated calibration loop (Q-coil) is efficient to compensate those effects to a large extend. The remaining bias as a function of the seafloor conductivity can be minimized by optimizing the dimensions and positioning of the housings leading to the ability to extend the ‘Golden Eye’to a multi-sensor-platform without sacrificing the envisaged resolution of geologic subsurface conductivity structures.

Biography:
Konstantin Reeck is employed as a scientific employee preceding a PhD position at the University of Bremen. He studied geosciences at the University of Bremen focusing on marine electromagnetics. During his studies he helped to develop the GoldenEye EM profiler. In his master thesis ‘Sensitivity of concentric loop CSEM to resolve structure and characteristics of submarine massive sulfide deposits’ he analyzed the electric in-situ conductivity and magnetic susceptibility of massive sulfide samples from the Central Indian Ridge to investigate their detectability by developing a 2.5D axisymmetric Finite-Element model of the GoldenEye in COMSOL Multiphysics.

 

 
1635
+
Electric field buoy measurements
Samantha Davidson, Capability Manager - Signatures, Ultra Electronics, UK

Abstract:
Buoys for marine surveillance typically employ acoustic sensors for target detection however there are situations and environments in which the efficacy of acoustic sensors can be reduced. In these cases a level of performance enhancement may be possible by using supplementary sensing techniques. One option under investigation is the use of underwater electric field (E-field) sensors to detect electromagnetic fields generated by the cathodic corrosion protection systems typically employed on marine vessels. Preliminary data will be analysed.

Biography:
Samantha graduated from Oxford University with a BA in Physics and subsequently completed a Doctorate in Magnetics. In 1997 Dr Davidson was appointed Leader for Ranges Research at Ultra and led the development of the electromagnetic modelling development for the Transmag ranges in-service with the UK MoD. She has 20 years experience in signature management including underwater measurements system design, commissioning, research and underwater data analysis worldwide. Samantha is currently a Capability Manager for Signatures in the Sensors and Ranges Team at Ultra Electronics Command and Sonar Systems.

 
1700
 
End of day 2
 
1900
+
CONFERENCE DINNER

Further details to follow

 

THURSDAY 29 JUNE

0830
 
Morning Refreshments
 
Track One
SESSION 8: Seafloor & Sub-Bottom Electromagnetic Exploration

SESSION CHAIR: Johan Mattsson, EM R&D Manager, PGS, Sweden

0900
+
Massive sulphide exploration with Controlled Source Electromagnetics at the Mid-Atlantic Ridge
Romina Gehrmann, Research Fellow, University of Southampton, UK

Abstract:
During the summer 2016 two cruised (M127 and JC138 ) conducted an interdisciplinary survey as part of the EU FP7 ‘Blue Mining’ project in the Trans-Atlantic Geotraverse (TAG) field 26ï‚° North, at the Mid-Atlantic Ridge, to study the geophysical signature of extinct seafloor massive sulphide (eSMS) deposits. The survey comprised high-resolution bathymetric imaging, magnetics, reflection and refraction seismics, seafloor coring and drilling, video imaging, and three types of electromagnetic experiments. Here, we present preliminary results from the controlled source electromagnetic (CSEM) experiments with a towed dipole source (DASI, designed at the University of Southampton), a pair of three-component electric field receiver dipoles (Vulcan, designed at Scripps Institution of Oceanography), and a seafloor source-receiver coil (MARTEMIS, designed at Geomar). Six multi-kilometre-long profiles were acquired with the DASI and Vulcan array. Our two-dimensional inversion results indicate that the CSEM experiment is sensitive to the conductive eSMS deposits and the resistive background to a depth of about 200 m. We will also show the effect of the rough topography in the TAG area as well as of navigational errors. Measurements with the MARTEMIS system were conducted in two work areas (MIR Zone and 3 Mounds Zone) along profiles of 8 and 12 km, respectively, with a depth penetration of up to 50 m. A first interpretation of data shows high conductivities throughout the MIR Zone.

Biography:
I have studied geophysics at the University of Leipzig (German Diplom in 2008) and have spent an Erasmus exchange at the University of Oulu. My Diplom dissertation was in collaboration with the Federal Institute for Geosciences and Natural Resources (BGR) about reflection seismic imaging and modelling of the bottom simulating reflector for gas hydrate studies. Then I worked as a research assistant at Geomar, the Helmholtz Centre for Ocean Research Kiel, on magnetotelluric data processing and assisting on field expeditions before starting my PhD at the University of Victoria, Canada. My dissertation concentrated on the uncertainty estimation of controlled source electromagnetic data inversion. After completing my PhD in 2014 I worked at the BGR on a joint seismic and CSEM study and am now a research fellow at the University of Southampton involved with two large European projects for eSMS exploration and studying fluid pathways for carbon capture and storage.

 

 
0925
+
Low frequency near-shore EM propagation for shallow water applications
David Calvo, Research Engineer / Section Head, U.S. Naval Research Laboratory, USA

Abstract:
Propagation of low-frequency electromagnetic energy in the near-shore environment can be used to support undersea communications, navigation, and survey applications.  Previous work has outlined the basic propagation mechanisms and pathways for interaction between a controlled source and undersea sensors.  While these applications have been well developed in deep water, limitations on the applications in shallow water had previously reduced interest since acoustic technology was adequate.  However, new interest in undersea robotics and coastal environmental measurements could take advantage of electromagnetic technology to augment acoustic techniques and better support coordination and data exchange systems.  This poster explores the propagation environment and specific aspects of the electromagnetic fields that could be exploited using recent measurements off the coast of South Florida and simulations. [Work Sponsored by the Office of Naval Research]

Biography:
Dr. David Calvo (Ph.D. 2001 MIT) has worked at the U.S. Naval Research Laboratory (Acoustics Division) on a variety of basic and applied research projects related to Undersea Defense since 2002.  He has been principal investigator on projects including undersea electric field sensing, undersea pipeline security, acoustic metamaterials, advanced acoustic sensing techniques, and numerical algorithms.  He has over 30 peer-reviewed publications and 2 patents.  He currently serves as a Section Head of the Advanced Acoustic Systems Development Section (Code 7165) at NRL.

 

 
0950
+
Mapping seafloor ore deposits in the Tyrhennian Sea with a new time-domain coincident coil system
Sebastian Hölz, Senior Researcher, GEOMAR - Helmholtz Center for Ocean Research Kiel, Germany

Abstract:
Recently there has been considerable economical and political interest in the potential use of marine mineral resources. An important aspect is the exploration of electrically conductive seafloor massive sulfides (SMS) deposits with high grades of metals. The search for SMS deposits is limited by the available technology to the detection of inactive sites, which from an economical standpoint should be the most promising. During research cruise on RV Poseidon, April 2015 we investigated an inactive SMS deposit at the Palinuro Seamount, Tyrrhenian Sea. Previous drillings had documented the presence of sediment buried SMS. Investigations were carried out with our newly developed marine time domain induction system (MARTEMIS), which consists of a coincident coil system.  Measurements show significantly increased amplitudes at some locations indicative for an increased conductivity of the seafloor. Besides to a qualitative data interpretation, we were also able to invert the data to conductivity model as a function of depth of the subsurface. The locations of high conductivity anomalies coincide and further extend the area where SMS were found in drillings. Thus, it seems evident that the area of mineralization is larger than previously detected and our results can serve as proof of principle for the usage of marine coincident loop TEM technology to not only detect near surface conductors, but also identify and quantify conductors at depth. Next to presenting details on the system and experiment, we also outline future development plans on how  to use the technology for mapping marine UXOs.

Biography:
Sebastian Hölz received his PhD for his work in landbased transient electromagnetics carried out in the Gobi desert in NW China under supervision of Prof. H. Burkhardt at the Technical University of Berlin in 2007. In the same year he joined the marine electromagnetic research group at the Helmholtz Centre for Ocean Research, GEOMAR in Kiel, Germany. Currently, his work deals with all aspects of marine controlled source electromagnetics like experiment and instrument design, implementation of experiments, data processing and interpretation with special focus on the investigations on methan hydrates with the Sputnik System and exploration for marine massive sulphides with the MARTEMIS system.

 
1015
 
POSTER HIGHLIGHTS – 2 minute overviews by the poster presenters
 
1030
 
COFFEE BREAK: visit exhibitors and posters
 
Track One
SESSION 9: Electromagnetic Surveillance & Communication Systems

SESSION CHAIR: Brian Glover, Physicist, Naval Surface Warfare Center, USA

1115
+
Geomagnetic modelling for MAD detection
George LeBlanc, Research Officer, National Research Council of Canada, Canada

Abstract:
Magnetic anomaly detection (MAD) is commonly used for threat detection of underwater and surface vessels. MAD technology may be carried out from either an airborne or surface platform. The sensor, a magnetometer, is typically towed below the platform or fixed using a boom or stinger. For accurate detection of a magnetic target signature, it is critical to identify and remove all unnecessary signatures that may mask the target. These include: the dynamic ambient magnetic field, survey platform noise, and earth’s geomagnetic model. The ambient magnetic field is removed through subtraction of a local time-synced magnetic base station and the International Geomagnetic Reference Field (IGRF). In the case of an airborne survey, aircraft noise is corrected through active and post-flight magnetic compensation algorithms. Finally, the geomagnetic model is the summation of all static magnetic contributions, principally local geology. The geomagnetic model is calculated by using regional magnetic survey data; however often there is insufficient survey coverage over the region of interest and the model needs to be calculated from multiple magnetic data sets each with unique survey specifications. This presentation will cover the method for calculating a geomagnetic model using data from a Western Canadian coastal region, the Canadian Forces Maritime Experimental Test Range (CFMETR). The presented geomagnetic model was calculated using magnetic measurements from full-scale aircraft over the past 30 years at variable resolutions and configurations.

Biography:
TBC

 
1140
+
Integrated techniques for predicting and assessing UAV-based Magnetic Anomaly Detection
Joe Keranen, Senior Scientist, White River Technologies, USA

Abstract:
The advent and use of new unmanned fixed-wing aircraft and rotorcraft have provided exciting new platforms for magnetic surveys and magnetic anomaly detection (MAD) for both commercial and naval applications.  These advances have been combined with commensurate miniaturization, automation, and improved sensitivity from new integrated MAD sensors that utilize the latest generation of atomic scalar and vector magnetometers.  However, these advancements and implementations on new platforms have also brought about new challenges and opportunities for mission planning, surveying, and analysis.  UAV’s fly with a different set of characteristics (maneuverability, control, navigation, endurance, and autonomy) than larger manned platforms.  To support the development of operational concepts, tactical UAV launch parameterization, and feasibility assessments; we have developed a MAD-enabled UAV simulation and analysis software environment.  Through a combination of simulation module demonstrations, probabilistic modeling and analysis, and software design concepts, we have worked to integrate current magnetic noise and target detection models and form a simulation environment that accurately and effectively predicts the probability of UAV-based magnetic sensing of at-sea targets.  At the heart of the software are modeling and simulation modules that account for launch platform, UAV platform, sensor, and environmental noise characteristics to output useful predictive metrics of probabilistic survey mission success.  This includes i) MAD sensor parameters, ii) UAV airframe noise, iii) geologic, geoatmosphereic, and met-ocean magnetic noise models, iv) estimates of target and/or clutter parameters and variability, v) launch platform properties, and overall UAV flight and search parameters.

Biography:
Mr. Keranen has over 15 years experience in marine geophysical research and development. His current research on the development of underwater systems that utilize advanced magnetic and electromagnetic sensor arrays deployed from unmanned platforms.  Previously, at Raytheon and the Penn State University Applied Research Laboratory, Mr. Keranen collaborated with engineers from the Naval Undersea Warfare Command (NUWC) to develop detection and classification algorithms.  Mr. Keranen’s graduate work focused on underwater acoustics culminating in a thesis on the effect of the ocean environment on the coherence of broadband signals.

 
1205
+
Investigating MAD aircraft compensation techniques to inform high precision UAV compensation
Harriet McGrain, Hydrodynamic Scientist, Dstl, UK

Abstract:
Anomalies in the Earth’s magnetic field can arise from the presence of ferrous materials or electrical circuits. These changes in the local magnetic field of the Earth can be measured using Magnetic Anomaly Detection (MAD), typically from a low flying aircraft. MAD sensors are mounted on a variety of platforms, from large winged aircraft to small rotary wing UAVs. These platforms often contain ferrous and conducting materials which give rise to noise associated with aircraft motion. These magnetic noise sources are categorised as the movement of permanently magnetised components, changes in the induced field or, eddy currents as the aircraft moves in the Earth’s field and can be removed from a magnetometer signal using the process of compensation. Data collected during aircraft compensation flight runs from a MAD trial has been analysed to investigate compensation modelling. Alternative inversion techniques (such as Singular Value Decomposition) for Tolles-lawson derivatives have been implemented to inform future, novel, processing requirements for high precision aeromagnetic compensation for UAVs.

Biography:
Harriet McGrain graduated from the University of Southampton in 2014 with a MSci in Oceanography. The findings of her dissertation titled, ‘The potential role of iron in the Madagascar bloom’ were published in the Journal of Geophysical Research, The Oceans. Harriet has since spent two years as a test engineer of fully integrated inertial navigation and positioning systems at Sonardyne, a subsea engineering company. In December 2016 Harriet joined Dstl as a junior scientist and has been involved in Magnetic Anomaly Detection trial planning and the analysis of supporting trial data.

 

 
1230
 
LUNCH BREAK
 
Track One
SESSION 10: Oceanographic Electromagnetics

SESSION CHAIR: Neil Stapleton, Principal Scientist, Dstl, UK

1345
+
Anthropogenic electromagnetic fields and impact on marine organisms
Andrew B Gill PhD, Director, Cape Eleuthera Institute, Bahamas

Abstract:
Anthropogenic electromagnetic fields are emitted into the marine environment by devices and cables which add to natural magnetic (e.g. geomagnetic field) and electric fields (e.g. bioelectric fields).  Many marine organisms from the smallest bacteria to the largest mammals are able to detect and respond to the natural emissions but our knowledge relating to whether they respond to anthropogenic sources (e.g. subsea cables) is poor. Current understanding on the topic shows that there are published cases of EM-sensitive animals responding to anthropogenic EMF sources in the marine environment. However, our interpretation of whether this is biologically meaningful suffers from lack of knowledge on the EMF emitted, whether it is A.C. or D.C. and how the response by the organisms is determined. Whilst EMF-organism interaction may appear as a very specific biological topic, the emission of low frequency electromagnetic fields, such as when transmitting power, increasingly will require specific consideration with regards to mandatory environmental impact assessment.  Appropriately assessing the potential environmental impact associated with EMF will need to be incorporated into the overall assessment of cable installation impact (including cable characteristics, route choice and electrical transmission type). A framework is suggested to enable EMF-organism interaction to be taken into account appropriately where necessary for the marine electromagnetics industry.

 

 

Biography:
Andrew Gill is the Director of the Cape Eleuthera Marine Institute, the Bahamas and a Visiting Research Fellow within Cranfield University Energy and Power. Andrew has 25+ years’ experience as an Applied Aquatic Ecologist working on the interface between environment and engineering focusing on interactions between marine organisms and marine/offshore renewable energy developments. Andrew has advised on marine EIA’s, and co-lead a European Commission project on the energy emissions (EMF and noise) associated with marine renewable energy devices. He currently works with University of Rhode Island on a project funded by the USA Bureau of Ocean Energy Management, determining the effect of subsea cables on of commercially important migratory fisheries species and advising on environmental monitoring protocols. Andrew serves as chair or member of several international scientific committees and societies. He has published 50+ peer reviewed papers, book chapters and reports many relating to marine/offshore renewable energy.

 
1410
+
Magnetic signature of diel vertical migrations of zooplankton
Cayla Dean, PhD Candidate, Nova Southeastern University, USA

Abstract:
Diel vertical migrations (DVM) of zooplankton can cause velocity fluctuations and a respective increase of the dissipation rate of turbulent kinetic energy dependent on zooplankton concentration (Dean et al. 2016). In this work, we used a 3D non-hydrostatic computational fluid dynamics (CFD) model (ANSYS Fluent) with Lagrangian particle injections (proxy for migrating organisms) to simulate the effect of turbulence generation by DVM. We tested a range of organism concentrations. The simulation at the extreme (10,000 organisms/m3) concentration of zooplankton showed an increase in dissipation rate of turbulent kinetic energy by two to three orders of magnitude during DVM over background turbulence (10-8 W kg-1). At the low (1000 organisms/m3) concentration, almost no turbulence above the background level was produced by DVM in the model. Seawater is an electric conductor; as a result, the motion of seawater in the magnetic field of the Earth induces electrical currents and, consequently, secondary magnetic fluctuations. Therefore, the turbulence produced by DVM can have a measureable magnetic signature. We have applied a magnetohydrodnamics (MHD) module to the CFD model to test this hypothesis. The MHD model results indicate that DVM of the extreme concentration of zooplankton create a magnetic signature on the order of 1 nT, which are relatively small but are well within the range of modern magnetometers. We also analyze the magnetic signature of DVM due to the difference in magnetic permeability between zooplankton and seawater using the ANSYS Maxwell electromagnetic model. This signature varies depending on the magnetic permeability of different species.

Biography:
Cayla Dean is a PhD Candidate in Oceanography with a focus in Physical Oceanography at Nova Southeastern University. She graduated obtained her Bachelor’s Degree in Marine Science from Coastal Carolina University in 2008 graduating Magna cum Laude. She also obtained her M.S. in Marine Biology from Nova Southeastern University in 2014. She is the primary author or co-author of five journal articles in peer-reviewed journals. She is the recipient of the 2006 NOAA Hollings Scholarship, the 2008 Who’s Who Among Students in American Universities and Colleges, and the 2017 Student Life Achievement Award for the Student of the Year. Her main research focus is studying the bioturbulence and magnetic signature produced by diel vertical migration of zooplankton through computational fluid dynamics simulations. She has also conducted research on fine-scale oceanographic processes using computational fluid dynamics simulations and laboratory experiments.


 
1435
+
Infrared sensing of surface scars
Aidan Burt, Scientist, Atlas Elektronik, UK

Abstract:
Underwater bodies have the potential to create thermal scars on the sea surface by transporting cooler fluid to the surface. This raises the possibility of using Infrared (IR) imagery to measure the resulting anomalies at the surface.

A new model has been developed to generate a pixel-based image of the sea surface as seen by an airborne IR sensor. The predicted scene includes both the IR radiation emitted from the sea surface and the scattering of ambient radiation off the sea surface. The model also accounts for the attenuating effect of different scattering and absorption processes in the atmosphere to accurately account for the received power levels.

The model has been used to explore the detectability of arbitrarily defined sea surface anomalies. A description of the models will be presented along with a selection of results to illustrate the key factors that impact on performance.

Biography:
TBC

 
1500
 
COFFEE BREAK: visit exhibitors and posters
 
Track One
SESSION 11: Vessel Electromagnetic Signature Prediction and Control

SESSION CHAIR: Samantha Davidson, Capability Manager, Ultra Electronics, UK

1545
+
Investigation into effects of ICAF system current on Underwater Electric Potential (UEP)
Robbie Ashby, CM Beasy, UK

Abstract:
Details of how an impressed current antifouling (ICAF) system is designed and constructed can influence flow of current between a sea-chest and the external environment, such that it may influence UEP of the vessel.  Some systems employ a dedicated bare steel cathode which is earthed to the hull inside the sea-chest, intended to capture all current delivered by the ICAF anodes. However, whether or not this happens  depends upon a number of factors including the position of the cathode within the sea-chest relative to the ICAF anode, the state of the cathode (which may accumulate calcareous deposits) and other factors such as the IR drop through the seawater to other cathode surfaces. In contrast, systems where the cathode  is isolated from the hull has the effect of ensuring that the cathode receives the same amount of current as is delivered by the anodes, but it is not guaranteed that some of this current has not come from some other anode (external to the sea-chest).

This paper investigates the effects of sea-chest and ICAF design on current flow into or out of the sea-chest, and how such current can influence the UEP. The surface vessel used in the simulation has an impressed current cathodic protection system as well as sacrificial anodes in some areas, and has bronze propellers with shaft grounding.

Biography:
TBC

 
1610
+
Localization of coating defects by using the impressed current cathodic protection system
Christian Thiel, PhD Student, University of Duisburg-Essen, Germany

Abstract:
In this contribution, we present numerical simulations of the motion-induced eddy currents and the corresponding magnetic fields of generic ship models utilizing the FEM solver COMSOL Multiphysics. The simulation domain includes a simplified model of the ship that is placed inside a homogeneous, static magnetic background field mimicking the emulated magnetic field of the measurement site Aschau in Germany. The ship model is undergoing typical motions to generate the stated eddy currents. Namely, jaw, pitch, and roll motions are simulated using corresponding rotation matrices in the framework of the software’s unique ‘moving mesh’ mode. In this context, special displacement factors that are computed to accordingly shift the mesh nodes yielding a deformation of the computational domains in the desired spatial directions. From the simulated eddy currents the dynamic induced and eddy current fields are computed, which define an essential contribution to the ship’s magnetic signature. In the present model, the dynamic induced and eddy current fields peak well below the ambient field and are now subject to further numerical analysis regarding different ship types, ship movements and motion frequencies. The aim is to provide reliable bounds for the dynamic induced and eddy current fields of the analyzed ship class with respect to realistic maritime conditions.

Biography:
Christian Thiel studied industrial engineering at the University of Duisburg-Essen and received his Bachelor degree in 2013 and his Master’s degree in 2015, respectively. Since 2015 he is working as a research associate and Ph.D. student at the department of General and Theoretical Electrical Engineering (ATE) at the University Duisburg-Essen where his main research topic is focusing on electromagnetic signatures of naval vessels in collaboration with the Technical Center for Ships and Naval Weapons (WTD71) of the Bundeswehr. He is also interested in the design and simulation of antennas used for 7T MRI, which he was working on his bachelor and master thesis and got experience in the numerical simulation of nano particles, mainly focusing on the plasmon resonance.

 

 

 
1635
 
End of day 3
 

FRIDAY 30 JUNE

0830
 
Morning Refreshments
 
Track One
SESSION 12: Vessel Electromagnetic Signature Prediction and Control

SESSION CHAIR: Eugene Lepelaars, Senior Research Scientist, TNO, Netherlands

0900
+
Closed loop degaussing – MASTERCODE project
Lt Cdr Hendrik Jacob Vink, Deputy Netherlands Coordinator, Centre for Ship Signature Management, Germany

Abstract:
Operating in shallow water areas and facing a potential mine threat set demanding requirements on underwater signatures for naval platforms. A system on board naval ships is desirable that shows the operational signatures and threat levels and which provides operator’s advice on active signature manipulation in order to reduce the threat: an operational ship signature management system (OSSMS). One of the OSSMS requirements is that the system is able to monitor the own magnetic underwater signature, which depends on the local Earth field and changes during operations. Analyses of the RIMPASSE trial measurements have shown that it is possible to develop a phenomenological (empirical) model that accurately estimates the static magnetic signature based on magnetic on-board data of only four carefully selected sensors, the background field and the degaussing currents. The MASTERCODE project will deliver the next step to get magnetic signature management to the fleet. It will deliver a ‘proof of concept’ and implementation strategies for various naval platforms. Having Closed Loop Degaussing Systems on board of naval platforms will contribute to enhance the survivability of naval platforms. It is essential to be able to control the susceptibility through signature reduction and enhance operational awareness. The results of the MASTERCODE project will enable our Navies to define the requirements in order to develop and acquire naval platforms that can face current and future threats.

Biography:
Lieutenant Commander (T) ing. H.J. Vink holds the position of Deputy Netherlands Coordinator at the Centre for Ship Signature Management (CSSM). CSSM, situated at Kiel (Germany), is tasked with supporting German and The Netherlands Ministry of Defense in their role as ‘ship design authority’. Within this scope fits the coordination of all joint signature Research and Development (R&D) activities.

 

 

 
09.25
+
A study on ship deperming coil system using High Temperature Superconducting cable technology
Megumi Hirota, Representative, Naval Ship Magnetic & UEP Research Committee, Japan

Abstract:
Naval ship deperming is effective to reduce the potential damage caused by seamines which senses magnetic field of the ship.  A few High Temperature Superconducting (HTS) coil systems were investigated to deperm naval ships which we expect shorter deperming time and lower manual workload for ship deperming operation, compared to conventional conductor coil systems.  Zero electric resistivity of HTS cable is attractive for large electric current applications and thus various developments of HTS cables for power transmission and high field magnet have been successfully conducted elsewhere.  Since the cable for ship deperming generates moderately high magnetic field over the volume of the ship, the high electric current is required depending on the design of the coil.  The electric properties of HTS materials are sensitive to the surrounding magnetic field and temperature.  We will discuss a coil design of flat multi-turn coil placed on the sea bed, which can be applied from large- to moderate-class ships, based on the reported development of HTS cable technology,

Biography:
She joined Technical Research and Development Institute, Ministry of Defense, Japan, (then Japan Defense Agency) in 1979, and was later appointed to the Chief of Magnetic Detection Research Section.  Her research was on magnetic detection technology and ship UEP signatures, by scale models and actual ships.  In 2010, she retired from civil service where she was the Deputy Director, Naval System’s Development Division, TRDI.  In 2012, Naval Ship Magnetic & UEP Research Committee (NMURC) was established and from 2014 she is the representative.

 
0950
+
Inverse modeling of a ship’s magnetic signature using regularisation methods
Mads Stormo Nilsson, Scientist, Norwegian Defence Research Establishment (FFI), Norway

Abstract:
Information about the underwater signatures of marine vessels is important for the protection against underwater threats. Although we want signature information independent of depth and range, we are limited by the positions of the measurement sensors used to obtain the signatures. Source modelling can be used to evaluate the signature at arbitrary depths and ranges from the vessel. To this end we have used the Prolate Spheroidal Harmonic (PSH) model to create equivalent source models of the magnetic signature of marine vessels.

Linear least-squares minimization algorithms can be used to fit the coefficients of the model to measured signature data. In order to generate models with good predictive ability it is important to avoid fitting to the noise in the measurement. This can be done by limiting the number of coefficients used in the fitting procedure, but finding the correct number of coefficients to use can be challenging.

Ordinary least-squares (OLS) can be modified to include a regularization term which penalizes complex models. Two such regularization methods are Lasso LARS and Ridge, which have been tested along with OLS and singular value decomposition (SVD). The resulting PSH-models have been evaluated based on a cross validation analysis, which determines their predictive ability.

The Lasso LARS method was found to generate the models with best predictive ability. The Ridge, SVD and OLS methods generated models with varying, but lesser predictive ability. Using Lasso LARS we have created an automatic method for generating robust source models of a ship’s magnetic signature.

Biography:
Mads Stormo Nilsson is a scientist at the Norwegian Defence Research Establishment (FFI). His work has been performed in the mine countermeasures group at the Maritime Systems Division. He received his Ph.D. from the University of Oslo, Department of Physics in 2013.

 

 
1015
 
POSTER HIGHLIGHTS – 2 minute overviews by the poster presenters
 
1030
 
COFFEE BREAK: visit exhibitors and posters
 
Track One
SESSION 13: Seafloor & Sub-Bottom Electromagnetic Exploration

SESSION CHAIR: Johan Mattsson, EM R&D Manager, PGS, Sweden

1115
+
Bayesian signal processing techniques for the detection of localised magnetic anomalies
Gareth Brown, Principal Scientist, Dstl, UK

Abstract:
The paper describes the implementation of a Bayesian inference model applied to the problem of passive underwater navigation and mapping of sub-seabed cavities. This has application to the resolution of localised structures, as a suitable trajectory of inertial and magnetic field measurements can be used to infer what lies beneath and to resolve target depth. Some potential applications of this technique include: improved identification of oil reservoirs; the detection of cavities and service pipes; and geophysical mapping as a means to navigate in GPS denied environments.

Using state-of-the-art Hamiltonian based Markov Chain Monte Carlo (MCMC) sampling methods, posterior distributions are presented that describe the likely range of model parameters consistent with the simulated data. This includes parameters that describe not only the local magnetic anomalies, but also the precision of the magnetometer and other background noise sources. The work investigates the impact of modelling spatially correlated noise sources.

The utility of the posterior distribution for computing probability of void maps is described. These maps condense the complex high dimensional space described by the posterior distribution into an easily understood 2D projection of areas most likely to contain sub-sea cavities. Projections in the xy and yz planes are presented and the impact of different sampling trajectories, and model specifications, are illustrated using this measure of performance.

Biography:
Dr Gareth Brown completed a PhD in theoretical physics at the University of Durham ten years ago. Since then he has undertaken research on a range of mathematical modelling and statistical inference problems at the Defence Science and Technology Laboratory. Past research topics include: numerical weather prediction, biometric identity management, multi-sensor fusion of sensor data, and high temperature radiative heat transfer. Gareth’s current focus is on helping to realising novel quantum technologies for defence and security and wealth creation.

 
1140
+
PETGEM: potential of 3D CSEM modelling using a new HPC tool for exploration geophysics
Octavio Castillo-Reyes, Associate PhD Student, Barcelona Supercomputing Center, Spain

Abstract:
The modelling tools help us to formalize and simplify the complexity we observe in nature. Although some contributions have been made to the development of algorithms for 3D CSEM modelling, our knowledge on this subject is still limited, with plenty of room for improvement. For instance, most codes that meet the requirements at real-scale modelling are commercial and often inaccessible to the wider scientific community, aspects that can all hamper advancements in the field. Furthermore, few of the open-source technologies are capable to exploit the power of cutting-edge High Performance Computing (HPC) architectures, which is crucial due 3D CSEM modelling is a computing intensive task. To help to reverse this trend, we present PETGEM (http://petgem.bsc.es), a Python code for the scalable solution of 3D CSEM on unstructured tetrahedral meshes using HPC platforms. To illustrate how it can help  industry and academy to make better decisions in exploration geophysics stage, we describe three 3D CSEM case scenarios: 1) How PETGEM can support the simulation of canonical models with an off-shore hydrocarbon reservoir, 2) How PETGEM can support models where interface materials are complex, namely, bathymetry scenarios and 3) How PETGEM exploits the computing capacity of the architecture. This cases depict the power of  using PETGEM as complementary tool together with seismic data and other geophysical information which help us to conduct exploration campaigns with a significant reduction of costs and avoids the risks real experiments would entail, and it even allow us render natural phenomena treatable and testable.

Biography:
Octavio Castillo Reyes is MSc. in Telecommunications and Computer Systems Engineering. His professional career has developed at the University of Veracruz. He has given national and international conferences (Cuba, Peru, Argentina, Spain, France, Germany, Ireland, Canada, Czech Republic, Greece, South Korea, United States). His current research topics focus on: methods and mathematical models to evaluate the performance of WSN, numerical simulation, parallel algorithms, finite elements and finite differences, HPC geophysical applications and electromagnetic modelling and inversion. In 2015, he won the JCC2015-BSC prize of ‘Your Thesis in Three Minutes’. Currently, he is a fellow CONACyT and conducts doctoral studies in Computer Architecture at the Polytechnic University of Catalonia. Develops its research in the CASE department at the BSC-CNS. His doctoral thesis, supported by European Project ‘Geophysical Exploration using Advanced Galerkin Methods’, is about the EFEM for the solution of 3D CSEM problems in geophysics and it’s coupling on HPC architectures.

 
1205
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Uncertainty quantification in the Controlled Source Electromagnetic Measurements
Nick Polydorides, Senior Lecturer, University of Edinburgh, UK

Abstract:
We present a computational framework for practical uncertainty quantification (UQ) in controlled source electromagnetic (CSEM) measurements using stochastic conductivity models. Unlike the conventional deterministic models that can predict the model’s response to a particular profile of the electrical properties, a stochastic model provides statistical information on the expectation and covariance of the measurements, derived from the adopted prior information assumptions on the electrical parameters. Our methodology combines elements of generalised sparse quadrature for the efficient calculation of the UQ integrals, as well as model reduction methods for expediting the model evaluations. Our numerical results show that subject to some mild assumptions on the smoothness of the random conductivity fields, our algorithm outperforms the convergence of the conventional Monte-Carlo method. Numerical results to illustrate the method are presented from three-dimensional CSEM simulations.

Biography:
Nick Polydorides has a B.Eng. in Electrical and Electronic Engineering from UMIST in 1998, a MSc in Computation from the University of Oxford in 1999 and a PhD in electrical tomography from the University of Manchester in 2002. He held postdoctoral positions at the School of Mathematics of the University of Manchester, and the Laboratory for Information and decision systems at MIT. In January 2010 he joined the Cyprus Institute as an Assistant Professor, from where he moved to the School of Engineering at the University of Edinburgh in September 2013 as a Senior Lecturer. He is the leader of the Agile Tomography Group and a member of the Institute for Digital Communications (IDCOM).

 
1230
 
LUNCH BREAK
 
Track One
SESSION 14: Oceanographic Electromagnetics

SESSION CHAIR: Brad Nelson, President, Aeromagnetic Solutions Inc., Canada

1345
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Isolating the magnetic signatures of internal waves
Eric Nieves, Student, Florida Atlantic University, USA

Abstract:
Internal waves in the ocean environment produce weak magnetic fields through induction in view of the fact that the seawater is conductive. The induced field can be detected in measurements of the magnetic field using a sensitive magnetometer. Isolating the magnetic signature of these ubiquitous phenomena from geomagnetic and noise sources requires careful analysis. The experiment uses two fixed bottom mounted magnetometers, one on shore and the other underwater, and an underwater bottom mounted ADCP.  Raw signals are adjusted for any data corruption and anthropomorphic interference, such as large spikes. Wavelet decomposition is used to automatically detect spikes in the magnetic data and allows for their replacement through various schemes. Then conventional and unconventional filtering techniques, including wavelet filtering and frequency domain cancellation, are used to show the signature of the internal wave. These results can be correlated with additional sensor information in an attempt to create a robust detection system for registering when an internal wave occurs in the future.

Biography:
Eric Nieves grew up on the Panhandle of Florida, where he gained many valuable experiences that enabled him to have a strong foundation in oceanography. Taking what he learned from both classroom and hands on research, he pursued a mechanical engineering degree through the University of Florida. Taking this more general degree, he graduated with his bachelors of science and moved to South Florida to complete his masters of science in ocean engineering. He currently works as a signal processing researcher under the direction of Dr. Pierre-Philippe Beaujean; his main objective includes using magnetic data and various filtering schemes to characterize ocean phenomena. Eric’s goal is to continue signal processing research linked to the ocean, in hopes to deliver meaningful data to the oceanography community.

 

 
1410
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Magnetic signature of surface waves in laboratory experiment
John Kluge, PhD Candidate, Nova Southeastern University, USA

Abstract:
Seawater, a conductive media, moving in Earth’s magnetic field causes secondary currents, which creates a magnetic signature. We have conducted a laboratory experiment to measure the magnetic signature of surface waves. The experiments were conducted at the SUrge STructure Atmosphere INteraction (SUSTAIN) facility, a large (22 m x 6 m x 2 m) air-sea interaction tank. We used a differential method, placing two Geometrics G-824 magnetometers at several locations on the outer tank walls, separated horizontally by one-half wavelength. This method effectively suppressed extraneous magnetic distortions and possible tank vibrations while doubling the magnetic signal of surface waves. The wave maker generated 2 m long waves with a 0.56 Hz frequency and 0.1 m amplitude. Wave elevation was measured using three Senix ultrasonic sensors positioned on the top of the tank. Experiments were conducted with freshwater, seawater, and when the tank was empty. The empty tank tests indicated that noise levels from the wave maker and surrounding facility are much smaller than the useful (differential) signal. Spectral analysis of the magnetic signal shows the main peak at the wave frequency of 0.56 Hz and less pronounced higher frequency harmonics, which are due to non-linearity of shallow-water surface waves. Our results suggest that the magnetic signature generated by surface waves were an order of magnitude larger than predicted by the traditional model (Podney 1975). Comparing various magnetic simulation results, the discrepancy may come from the difference of magnetic permeability in water and air that is not accounted in the traditional model.

Biography:
John Kluge is a PhD candidate in Nova Southeastern University’s (NSU) physical oceanography laboratory, located in Dania Beach, Florida. Originally from a farm in Graham, WA (a small town outside of Seattle), he moved to Dania Beach to earn his master’s degree in marine science. John was awarded his degree for his research on the mathematical modeling of diseases in coral populations from the red sea in 2015. Johns modeling work in this project sparked his interest in mathematical models, which ultimately led him to change fields and apply for a PhD candidacy in NSU’s physical oceanography laboratory. Since joining the lab, John has primarily worked on collecting and processing magnetic signal data from surface waves, which includes signal processing, fieldwork, and spectral analysis. In his personal time, John enjoys spending time in or on the water with his hobbies including diving, fishing, and boating.

 
1435
 
COFFEE BREAK: visit exhibitors and posters
 
Track One
SESSION 15: Electromagnetic Surveillance & Communication Systems

SESSION CHAIR: Romina Gehrmann, Research Fellow, University of Southampton, UK

1520
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Real-time underwater object detection based on DC resistivity using high-precision instrument
Sung-Ho Cho, Researcher, Korea Institute of Geoscience & Mineral Resources, South Korea

Abstract:
The environmental noise is large in shallow water and the detection capabilities of conventional methods, such as acoustic, magnetic, and UEP methods, are degraded. Passive detection methods can be greatly affected by existence of prerecorded submarine signatures. Therefore, the detection of state-of-the-art stealthy submarines becomes more difficult under acoustically, magnetically, and electrically noisy environmental conditions, particularly in shallow water. Therefore, we propose a new detection method for underwater moving objects using the active electric field to counteract future anti-submarine warfare. The biggest advantage of the new method is that we can neutralize the submarine stealth strategies for conventional detection methods, because the responses of an underwater object are caused by the difference in the electrical properties between an object and seawater. A dedicated detection system was implemented for the demonstrations of the new method. The 32-bit resolution data acquisition unit (Noise-free 1-μV DC measurement in the range of 2.5 V), submersible carbon fiber electric field sensors, and data processing and control unit of the system were totally in-house developed. The new method was verified using the real sea experiment; the field conditions were 8-m water depth and a downscaled cylindcal fiber-reinforced plastic (FRP) object was used as the target object. The target object was towed by a motorboat; the submerged depth was maintained at 3.5-m. The total length of the detection line was 63 m. Real-time monitoring was performed at 5-Hz refresh rates. The target responses were observed in the range of ±6 m around the detection line.

Biography:
Sung-Ho Cho received the B.S. degree in electronic engineering from Chungnam National University, Daejeon, Korea, in 2008. He received the M.S. and Ph.D. Integrated degree in geophysical exploration at Korea University of Science and Technology (KIGAM campus), in 2017. From 2008 to 2010, he was a Research Assistant with Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon, Korea. He is a postdoctoral research fellow at KIGAM (2017~). His research interest includes the development of advanced geophysical instruments and high-precision data acquisition system, low noise submersible electric field sensors, military applications of geophysical survey methods, and fundamental study of electromagnetic (EM) and direct current (DC) resistivity exploration.

 

 
1545
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SQUID based magnetic full tensor gradiometer for maritime application
Michael Schneider, PhD Student / Scientist, Technische Universität Ilmenau, Germany

Abstract:

A new system for submarine application of cryo-cooled SQUID (superconducting quantum interference device) is introduced. Those sensors are mounted on a towed underwater platform and allow the passive measurement of the full magnetic gradient tensor information. The depressor based platform carries a pressurized hull, containing all important components for the underwater operation of a liquid Helium cooled system at ambient pressure. The most important component is a special designed Dewar which handles the reservoir for the cryogen liquid and simultaneously provides the operating conditions of the SQUID sensors by thermal and electromagnetic shielding. The electronics for power supply, control and readout of the sensors is also placed inside the pressurized hull. Since a dipole localization algorithm requires knowledge about localization and orientation of the system during the entire measurement time, a combination of a GPS on the ship together with ultra-short baseline (USBL) is realized. The evaporated Helium gas is released to the surrounding water using a compressor. All components are designed for low-distortion operation to support the applied sensors which have a sensitivity of below 100 fT/(m*sqrt(Hz)) under field conditions and operate at a sampling rate of 1 kHz. These properties are supported by an innovative data processing that eliminates measurement artefacts out of the acquired signals and offers a trustable fundament for our advanced inversion algorithms. These algorithms use the properties of the sensors as well as a well-founded theory to allow the localization of various objects with high accuracy.

Biography:
Michael Schneider studied technical physics at the Friedrich-Schiller University in Jena. After he got his diploma in 2010, Michael changes to the Leibniz-Institute of Photonic Technology (IPHT) in Jena and works as a scientist as well as start his PhD. In 2013, Michael changes to the Institute of Biomedical Engineering and Informatics (BMTI) at the technical university of Ilmenau to complete his thesis. But during this time, a close relation and a scientific partnership still connects Michael to the IPHT and the group of Dr. Ronny Stolz. Now, he is member of both groups, the research group ‘magnetometry’ at IPHT and the ‘Multimodal data analysis in biomedical engineering’ group at BMTI.

 
1610
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Degaussing system performance prediction: validation of FEM simulations of a naval vessel
Bart Jan Peet, Researcher, TNO, Netherlands

Abstract:
FEM simulation software is used extensively for the design and performance prediction of ship degaussing systems. In the past TNO has used the FEM package COMSOL Multiphysics to study the magnetic signature levels of conceptual designs of naval platforms and to determine the optimum positions of degaussing coils. In order to obtain meaningful results, proper validation of these FEM tools is imperative through comparison of the simulated data to real measurements of naval platforms. In this study COMSOL was used to simulate both the induced signature and the coil effects of a Dutch naval vessel. The theoretically achievable degaussing performance was determined based on these simulations and a least squares algorithm. The simulations were compared with magnetic signature and coil effect measurements conducted at the Wilhelmshaven range in Germany. Overall, simulated and measured data are in good agreement. Both the magnitude of the fields of the degaussing coils and the induced signature can be simulated with an accuracy within 10% to 30%. The main error contributions are limitations in the accuracy of the measurements due to misalignments and the uncertainties in the steel mass distribution across the ship geometry. Finally, the theoretically predicted signature level of the degaussed ship is lower by a factor of two compared to the manually calibrated degaussing system. This suggests that by using more advanced calibration methods the performance of the existing coil layout can be improved.

Biography:
Bart Jan Peet is a researcher at the Electronic Defence department of TNO. He obtained his masteR’s degree in Applied Physics at the TU Delft where he specialized in nuclear physics and radiation detection for medical imaging. At TNO he works on a wide range of topics including electric and magnetic underwater ship signatures, infrared signatures, antenna modelling and wind turbine radar interference.

 
1635
 
Closing remarks – Romina Gehrmann, Research Fellow, University of Southampton, UK
 
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