scholarly journals Compact Quantum Magnetometer System on an Agile Underwater Glider

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1092
Author(s):  
Brian R. Page ◽  
Reeve Lambert ◽  
Nina Mahmoudian ◽  
David H. Newby ◽  
Elizabeth L. Foley ◽  
...  
Keyword(s):  
Test Procedure ◽  
Reduction Process ◽  
Ground Truth ◽  
Sensor Technology ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Underwater Glider ◽  
Combined System ◽  
Extended Operation ◽  
Quantum Magnetometer

This paper presents results from the integration of a compact quantum magnetometer system and an agile underwater glider for magnetic survey. A highly maneuverable underwater glider, ROUGHIE, was customized to carry an increased payload and reduce the vehicle’s magnetic signature. A sensor suite composed of a vector and scalar magnetometer was mounted in an external boom at the rear of the vehicle. The combined system was deployed in a constrained pool environment to detect seeded magnetic targets and create a magnetic map of the test area. Presented is a systematic magnetic disturbance reduction process, test procedure for anomaly mapping, and results from constrained operation featuring underwater motion capture system for ground truth localization. Validation in the noisy and constrained pool environment creates a trajectory towards affordable littoral magnetic anomaly mapping infrastructure. Such a marine sensor technology will be capable of extended operation in challenging areas while providing high-resolution, timely magnetic data to operators for automated detection and classification of marine objects.

Airborne geophysical surveys in Greenland in 1998

1999 ◽  
pp. 34-38 ◽  
Author(s):  
Thorkild M. Rasmussen ◽  
Leif Thorning
Keyword(s):  
High Resolution ◽  
Geophysical Data ◽  
Digital Data ◽  
Geological Survey ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Original Series ◽  
Geophysical Surveys ◽  
The Government

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, T. M., & Thorning, L. (1999). Airborne geophysical surveys in Greenland in 1998. Geology of Greenland Survey Bulletin, 183, 34-38. https://doi.org/10.34194/ggub.v183.5202 _______________ Airborne geophysical surveying in Greenland during 1998 consisted of a magnetic project referred to as ‘Aeromag 1998’ and a combined electromagnetic and magnetic project referred to as ‘AEM Greenland 1998’. The Government of Greenland financed both with administration managed by the Geological Survey of Denmark and Greenland (GEUS). With the completion of the two projects, approximately 305 000 line km of regional high-resolution magnetic data and approximately 75 000 line km of detailed multiparameter data (electromagnetic, magnetic and partly radiometric) are now available from government financed projects. Figure 1 shows the location of the surveyed areas with highresolution geophysical data together with the area selected for a magnetic survey in 1999. Completion of the two projects was marked by the release of data on 1 March, 1999. The data are included in the geoscientific databases at the Survey for public use; digital data and maps may be purchased from the Survey.

scholarly journals A Novel Noise Reduction Method of UAV Magnetic Survey Data Based on CEEMDAN, Permutation Entropy, Correlation Coefficient and Wavelet Threshold Denoising

Entropy ◽  
2021 ◽  
Vol 23 (10) ◽  
pp. 1309
Author(s):  
Yaoxin Zheng ◽  
Shiyan Li ◽  
Kang Xing ◽  
Xiaojuan Zhang
Keyword(s):  
Noise Reduction ◽  
Correlation Coefficient ◽  
Field Experiments ◽  
Reduction Method ◽  
Magnetic Data ◽  
Permutation Entropy ◽  
Magnetic Survey ◽  
Intrinsic Mode Functions ◽  
Real Signal ◽  
The Real

Despite the increased attention that has been given to the unmanned aerial vehicle (UAV)-based magnetic survey systems in the past decade, the processing of UAV magnetic data is still a tough task. In this paper, we propose a novel noise reduction method of UAV magnetic data based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), permutation entropy (PE), correlation coefficient and wavelet threshold denoising. The original signal is first decomposed into several intrinsic mode functions (IMFs) by CEEMDAN, and the PE of each IMF is calculated. Second, IMFs are divided into four categories according to the quartiles of PE, namely, noise IMFs, noise-dominant IMFs, signal-dominant IMFs, and signal IMFs. Then the noise IMFs are removed, and correlation coefficients are used to identify the real signal-dominant IMFs. Finally, the wavelet threshold denoising is applied to the real signal-dominant IMFs, the denoised signal can be obtained by combining the signal IMFs and the denoised IMFs. Both synthetic and field experiments are conducted to verify the effectiveness of the proposed method. The results show that the proposed method can eliminate the interference to a great extent, which lays a foundation for the further interpretation of UAV magnetic data.

Minimization of sludge production in biological processes: an alternative solution for the problem of sludge disposal

2002 ◽  
Vol 46 (10) ◽  
pp. 63-70 ◽  
Author(s):  
S. Deleris ◽  
V. Geaugey ◽  
P. Camacho ◽  
H. Debellefontaine ◽  
E. Paul
Keyword(s):  
Biological Treatment ◽  
Reduction Process ◽  
Aeration Tank ◽  
Urban Wastewater ◽  
Combined System ◽  
Active Biomass ◽  
Sludge Disposal ◽  
Autotrophic Biomass ◽  
Sludge Settling ◽  
Sludge Production

A combined system associating activated sludge and ozonation was evaluated for the treatment of urban wastewater. Experiments have shown that 70% reduction in sludge production can be reached (compared to a reference system running in low loaded conditions Yobs = 0.28 g VSS.g COD-1) by applying an ozone dosage of 0.05 g O3/g VSStreated. Recycling of the ozonated sludge to the aeration tank induces a slight increase in effluent COD, but the biological treatment performance is maintained. Nitrification capabilities are not altered by the sludge reduction process and active biomass measurements revealed that autotrophic biomass seems to be less affected than the heterotrophs. Significant improvements in sludge settling characteristics are observed.

UAV high-resolution magnetic mapping of the Chenaillet ophiolite, in the Alps

2021 ◽  
Author(s):  
Pauline Le Maire ◽  
Denis Thieblemont ◽  
Marc Munschy ◽  
Guillaume Martelet ◽  
Geoffroy Mohn
Keyword(s):  
Magnetic Field ◽  
Ground Level ◽  
Weather Conditions ◽  
Geological Mapping ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Magnetic Signal ◽  
Alpine Orogeny ◽  
Above Ground Level ◽  
Slow Spreading

<p>Continent-Ocean Transitions (COT) and ultra-slow spreading ridges, floored by wide area of exhumed serpentinized mantle, bear strong amplitude magnetic lineations. However, whether these anomalies are linked to inversions of the direction of the magnetization (therefore characterized as isochrones of seafloor spreading) or to structural and lithological contrasts remains an open question. Generally, marine magnetic data acquired at sea surface along profiles, are too low resolution to image the intensity variations of the magnetic field at a kilometric scale. Performing a dense deep tow magnetic survey at a present-day COT or ultra-slow spreading system would be better to determine the sources of the magnetic signal but remains expensive. To go ahead, a valuable alternative to address these questions is to record the magnetic signal on ophiolite representing remnants of COT and oceanic systems sampled in orogenic system. We worked on the Chenaillet Ophiolite (French Alps), which represents a fossil COT or ultra-slow spreading system integrated to the Alpine orogeny. This ophiolite escaped high-pressure metamorphism and has only been weakly deformed during Alpine orogeny, preserving its pre-orogenic structure.</p><p>We performed an UAV magnetic survey using fluxgate magnetometers in complex conditions due to the altitude (> 1800 m), the strong topography variations and the weather conditions (negative temperatures, snow). Despite these difficulties, which highlight the viability of UAV for geophysical measurements, a survey of 20 square kilometers with 219 km of profiling was completed 100 m above ground level. Flight line spacing is 100 m above the ophiolitic basement and 200 m above the sedimentary units. Another magnetic UAV survey was flown with another UAV to map a small area 10 m above ground level. Magnetic anomaly maps were computed after standard processing (e.g., calibration/compensation, temporal variation and regional magnetic field corrections, levelling).</p><p>Our first results evidence well-defined magnetic anomalies clearly linked to serpentinite. This shows that the magnetic signal is of sufficient resolution to contribute to a revision of the cartography of the massif combining geological observations and magnetic data.</p><p>In addition, the magnetic susceptibility was measured on 60 outcrops, to support interpretation.</p><p>In this presentation, we focus on the magnetic acquisition campaigns, processing and 2D/3D interpretations by forward modelling and data inversion. Lastly, two items are discussed: 1) contribution of magnetic UAV surveys for geological mapping; and 2) implication of the results on the Chenaillet massif to discuss the contribution of magnetic mapping to the understanding of the TOC or ultra-slow spreading system.</p>

Merging airborne magnetic surveys into continental‐scale compilations

Geophysics ◽  
2003 ◽  
Vol 68 (3) ◽  
pp. 988-995 ◽  
Author(s):  
Brian R. S. Minty ◽  
Peter R. Milligan ◽  
Tony Luyendyk ◽  
Timothy Mackey
Keyword(s):  
Least Squares Method ◽  
Weighted Least Squares ◽  
Holistic Approach ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Long Wavelength ◽  
Weighted Least Squares Method ◽  
Continental Scale ◽  
Original Survey ◽  
Airborne Magnetic

Regional compilations of airborne magnetic data are becoming more common as national databases grow. Grids of the magnetic survey data are joined together to form geological province‐scale or even continental‐scale compilations. The advantage of these compilations is that large tectonic features and geological provinces can be better mapped and interpreted. We take a holistic approach to the joining of survey grids. The leveling of the grids into a regional compilation is treated as a single inverse problem. We use the weighted least‐squares method to find the best adjustment for each survey grid such that the data value differences in the grid overlap areas are minimized. The method spreads any inconsistencies between grids among all of the grid overlap areas and minimizes the introduction of long‐wavelength errors into the composite grid. This is an improvement on the conventional approach of joining grids sequentially. A comparison of leveled data over Western Australia with diurnally‐corrected long aeromagnetic traverses shows long‐wavelength errors of about 200 nT over distances of more than 5000 km. This is an improvement on the sequential grid‐joining method, which gives errors of about 450 nT over the same distance. The application of the method to a smaller area covered by good quality surveys resulted in long‐wavelength errors of about 30 nT over a distance of 1200 km. This is within the estimated accuracy of the original survey measurements. The new method is also fast—what used to take many weeks of effort can now be achieved in a matter of hours.

Interpretation of airborne magnetic survey of Gabel Um Tineidba area, south eastern desert, Egypt

2015 ◽  
Vol 12 (6) ◽  
pp. 563-576
Author(s):  
Tharwat H. Abdel Hafeez
Keyword(s):  
Analytical Signal ◽  
Eastern Desert ◽  
Structural Features ◽  
Geological Mapping ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Aeromagnetic Survey ◽  
Reasonable Proportion ◽  
The Cost ◽  
Airborne Magnetic

The study area is regionally covered by rock exposures ranging in age from the Precambrian to Quaternary. The aeromagnetic survey is a useful tool that help in geological mapping, providing information at a reasonable proportion of the cost of ground mapping. The reduced to the northern magnetic pole (RTP) map was separated into regional and residual magnetic component maps by the computed power spectrum of the magnetic data. The estimated mean depths of both regional and residual magnetic sources were found to be 2510 m and 383 m respectively. Also, two advanced techniques were used to analyze the depth magnetic data. These methods are analytical signal (AS) and source parameter imaging (SPI). The results of average depth estimates both methods (–950 m). These depth values were helped -to great extent- for define the direction of throw for the interpreted faults in the basement tectonic map. The statistical analysis shows that, most of the welldeveloped structural features are oriented mostly in the N-S, NNE-SSW, NW-SE and NNWSSE trending faults are considered the main trends affecting the distribution of the radioactive minerals.

scholarly journals On line-integrals of the diurnal magnetic variations

1928 ◽  
Vol 119 (782) ◽  
pp. 182-196 ◽  
Keyword(s):  
Electric Current ◽  
Potential Gradient ◽  
Electromagnetic Theory ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Electric Currents ◽  
Direct Measurements ◽  
On Line ◽  
Current Densities ◽  
Current Flows

1. According to electromagnetic theory, the line-integral ∫ H . ds of the magnetic force H taken round any closed curve is equal to 4πI, where I is the electric current threading the curve, H and I being measured in c.g.s. units. Such line-integrals have been calculated by Gauss and many later investigators for various curves on the earth’s surface, in order to determine whether any electric current flows upwards or downwards across the surface. Modern computations for large areas lead in general to values of ∫ H . ds differing from zero by amounts that correspond to current-densities of the order 3·10 -2 ampere/km. 2 . The magnetic field of such currents would account for 2 or 3 per cent, of the earth’s surface field. These results are inconsistent with the direct measurements of the atmospheric electric potential gradient and the ionisation of the air, which indicate a verticalcurrent-density of the order 3·10 -6 amp./km. 2 . If the magnetic estimates are reliable, the discrepancy indicates either that atmospheric electric currents exist which escape measurement, though they are 10,000 times as great as those which are measured, or that the relation ∫ H . ds = 4πI, which is one of the foundations of electromagnetic theory, is not strictly correct. These alternatives are so remarkable that the magnetic evidence must be above suspicion if it is to gain credence. Dr. L. A. Bauer holds that the results got from independent sets of data, for different epochs, and the mutual accordance of the results from neighbouring areas, justify the acceptance of the non-zero line-integrals, and that to explain them away it is necessary to assume quite unlikely systematic errors in the magnetic data. Other investigators show less conviction: for example, Sir Frank Dyson and H. Furner conclude that “though there is some evidence for Prof. Bauer’s results, the existence of vertical electric currents is not indicated with any great certainty.” But though the magnetic evidence may not be conclusive, it cannot be lightly dismissed, and in view of the importance of the question Sir Arthur Schuster has recently urged the desirability of a detailed magnetic survey of a small area as the best means of obtaining a definite conclusion.

scholarly journals Exploration of Iron Sand at The Eastern Coast Area of Binangun in Cilacap Regency Using Magnetic Survey

2017 ◽  
Vol 7 (2) ◽  
pp. 71 ◽  
Author(s):  
Sehah Allasimy ◽  
Sukmaji Anom Raharjo ◽  
Iska Andriyanto
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomaly ◽  
Data Interpretation ◽  
Research Area ◽  
Eastern Coast ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Magnetic Field Data ◽  
Geological Information ◽  
Geoelectric Data

<p class="AbstractText">Exploration of the spread of iron sand on the eastern coastal of Binangun District in Cilacap Regency has been conducted using the magnetic surveys. The magnetic data acquisition was conducted in April 2017. The total magnetic field data obtained is processed, so that can be obtained the local magnetic anomaly data. The modeling of the local magnetic anomaly data is performed on the trajectory of AB that extending from the position point of 109,274698° E and 7.686620° S to 109.2296195° E and 7.689099° S so that obtained various model of the subsurface anomalous objects. Interpretation on the subsurface anomalous objects is done to estimate the types of rocks and their formations based on the magnetic susceptibility value of each object which supported by the geological information of the research area. Based on the interpretation results to be obtained two layers of subsurface rocks that can be estimated as the iron sand that coexists with silt dan clay derived from the alluvium formation. The first rock has a length of 1238.2 meters, a depth of 1.709 – 20.513 meters, and a magnetic susceptibility value of 0.0183 cgs unit. The second rock has a length of 643.055 meters, a depth of 16.524 – 34.188 meters, and a magnetic susceptibility value of 0.0174 cgs unit. The results of this research are also supported by the results of geoelectric data interpretation, where the iron sand that coexists with silt and clay is found at a depth of 9.42 – 19.48 meters with a resistivity value of 52.99 Ωm at Geo-1 point; and a depth of 10.56 – 22.20 meters with resistivity value of 49,03 Ωm at Geo-2 point. Based on the results of of this research, the eastern coastal area of Binangun District is estimated to contain potentially iron ore and economically is a prospect for exploitation.</p>

scholarly journals Magnetic and spectrometric studies of Al-Gor area, Southwestern Sinai, Egypt

2021 ◽  
Vol 51 (3) ◽  
pp. 207-223
Author(s):  
Mostafa A. M. ZAEIMAH
Keyword(s):  
Gamma Ray ◽  
Magnetic Anomalies ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Rock Types ◽  
Ore Minerals ◽  
Um Bogma Formation ◽  
Copper Zinc ◽  
Relationship Of ◽  
Southwestern Sinai

Al-Gor area is a part of Southwestern Sinai of Egypt. It is considered as one of the most promising areas for mineralization in Egypt, being rich in many mineral deposits of: manganese, iron, copper, zinc, lead, cobalt, nickel, silver, gibbsite, and uranium. Besides, some industrial ore minerals such as kaolin and glass sand,… etc. are also found in this area. The area was studied by Gama-ray spectrometry to trace the radioactive anomalies, their concentrations and their relationship to the existing rocks, and by magnetic survey to study the relationship of radioactive anomalies and their trends with the trends of geological structures. The gamma-ray spectrometric maps show different levels over the surveyed area, which reflect contrasting radioelement contents for the exposed various rock types. The highest radiospectrometric levels are located in the northwest southeast direction and some scattered parts all over the study area. They are mainly associated with Um-Bogma Formation, bearing gibbsite. The study area possesses radiospectrometric ranging between 0.6 and 110.9 Ur as a total-count, 0.1 to 1.8 % for K, 0.1 to 99 ppm for eU and 0.1 to 23 ppm for eTh. The qualitative analyses of magnetic data show the existences of a number of different magnetic anomalies, with different amplitudes and frequencies as well as trends. From the application of spectral analyses of magnetic data, the regional and residual depths of magnetic anomalies can be computed. The first depth represents the regional (deep-seated) anomalies, at about 75 m and the residual (shallow-seated) anomalies, at about 20 m. The trends of the structures as derived from the spectrometric and ratio maps correspond to those inferred from the residual-component magnetic map, which reflects the effect of structures on the concentration of radioactive elements and, consequently mineralization.

EXPLORING SEULIMEUM FAULT IN ACEH, INDONESIA USING MAGNETIC METHOD

2016 ◽  
Vol 78 (8-5) ◽  
Author(s):  
Nordiana Mohd Muztaza ◽  
Muhammad Taqiuddin Zakaria ◽  
Rosli Saad ◽  
Nur Azwin Ismail ◽  
Muhammad Syukri
Keyword(s):  
Fault Detection ◽  
Fault Zones ◽  
Magnetic Data ◽  
Magnetic Method ◽  
Magnetic Survey ◽  
Residual Value ◽  
Measurement Device ◽  
Trend Pattern ◽  
Geological Map ◽  
Alternative Measurement

The study explores the use of magnetic method as an alternative measurement device for Seulimeum fault detection and location in Krueng Raya, Ie Seu Um, Iejue, Lamtamot (Aceh Besar) and Tangse, Pidie (Indonesia). The magnetic survey was performed using G-856 proton magnetometer and the spacing between stations was depends on the study location; Krueng Raya (50-300 m spacing randomly), Ie Seu Um (10-30 m randomly), Iejue (50 m), Lamtamot (50-70 m) and Tangse (50-200 m). The magnetic data was processed by utilising Microsoft excels and Surfer 10 software which was displayed in a form of contouring and revealed fault zones. The local magnetic value in Krueng Raya was -700 to 650 nT, Ie Seu Um was -500 to 300 nT, Iejue was -150 to 600 nT, Lamtamot was -200 nT to 200 nT and Tangse was -750 to 350 nT. The magnetic results showed the trend pattern of low and high residual value surround the study area. The highly contrast of magnetic contouring map was interpreted as fault zones. All results show that the trend pattern of fault mapped by magnetic method was trending from northwest to southeast direction. The magnetic residual map was correlated with geological map which show the existence of Seulimeum fault and proved that the study area is bounded by small faults.

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