Academic literature on the topic 'Airborne TDEM'
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Journal articles on the topic "Airborne TDEM"
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Sunderland, Andrew, Ray Lockwood, Li Ju, and David G. Blair. "Low-frequency rotational isolator for airborne exploration." GEOPHYSICS 82, no. 2 (March 1, 2017): E27—E30. http://dx.doi.org/10.1190/geo2015-0521.1.
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We have determined the performance of a passive rotational vibration isolator for a time-domain airborne electromagnetic (TDEM) receiver. The isolator uses neutrally buoyant flotation to provide very soft suspension and a very low resonant frequency of 0.065 Hz ± 0.005 Hz. One of the limitations of mapping deeper targets in areas of conductive overburden with TDEM systems is that low-frequency coil-vibration noise provides a lower bound to the transmitter base frequency (typically limited to 25 Hz). The purpose of this new isolator is to improve coil vibration related noise between 5 and 20 Hz to allow the transmitter base frequency to be reduced. A fixed-wing flight test determined that a receiver inside the new isolator had five times less rotational noise at 10 Hz than a current commercial system.
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Zhdanov, Michael S., Dmitriy A. Pavlov, and Robert G. Ellis. "Localized S‐inversion of time‐domain electromagnetic data." GEOPHYSICS 67, no. 4 (July 2002): 1115–25. http://dx.doi.org/10.1190/1.1500372.
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Interpretation of time‐domain electromagnetic (TDEM) data over inhomogeneous geological structures is a challenging problem of geophysical exploration. The most widely used approach of interpreting TDEM data is based on the smooth 1‐D layered resistivity inversion. We have developed an effective technique of fast TDEM inversion based on thin‐sheet conductance approximation that we call S‐inversion. In this paper we extend the S‐inversion technique, approximating the conductivity cross‐section by adding a local inhomogeneous disk with an excess conductance ΔS to the horizontal conductive thin sheet used in S‐inversion. Localized S‐inversion determines the distribution of this excess conductance as a function of a depth and a horizontal coordinate. This new method takes into account the limited horizontal extent of the inhomogeneities, localizing inversion. The numerical modeling results and inversion of practical TDEM data demonstrate that the method resolves local geological targets better than traditional 1‐D inversion and original S‐inversion. The method can be applied to interpret both ground and airborne TDEM data sets.
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Viezzoli, Andrea, Vladislav Kaminski, and Gianluca Fiandaca. "Modeling induced polarization effects in helicopter time domain electromagnetic data: Synthetic case studies." GEOPHYSICS 82, no. 2 (March 1, 2017): E31—E50. http://dx.doi.org/10.1190/geo2016-0096.1.
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We have developed a synthetic multiparametric modeling and inversion exercise undertaken to study the robustness of inverting airborne time-domain electromagnetic (TDEM) data to extract Cole-Cole parameters. The following issues were addressed: nonuniqueness, ill posedness, dependency on manual processing and the effect of constraints, and a priori information. We have used a 1D layered earth model approximation and lateral constraints. Synthetic simulations were performed for several models and the corresponding Cole-Cole parameters. The possibility to recover these models by means of laterally constrained multiparametric inversion was evaluated, including recovery of chargeability distributions from shallow and deep targets based on analysis of induced polarization (IP) effects, simulated in airborne TDEM data. Different scenarios were studied, including chargeable targets associated with the conductive and resistive environments. In particular, four generic models were considered for the exercise: a sulfide model, a kimberlite model, and two generic models focusing on the depth of investigation. Our study indicated that, in cases when relaxation time ([Formula: see text]) values are in the range to which the airborne electromagnetic is most sensitive (e.g., approximately 1 ms), it is possible to recover deep chargeable targets (to depths more than 130 m) in association with high electrical conductivity and in resistive environments. Furthermore, it was found that the recovery of a deep conductor, masked by a shallower chargeable target, became possible only when full Cole-Cole modeling was used in the inversion. Lateral constraints improved the recoverability of model parameters. Finally, modeling IP effects increased the accuracy of recovered electrical resistivity models.
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Silic, Jovan, and Todd Ballantyne. "Discoveries through innovation in applications of airborne and ground TDEM in very conductive environment." ASEG Extended Abstracts 2004, no. 1 (December 2004): 1–7. http://dx.doi.org/10.1071/aseg2004ab131.
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Herckenrath, D., G. Fiandaca, E. Auken, and P. Bauer-Gottwein. "Sequential and joint hydrogeophysical inversion using a field-scale groundwater model with ERT and TDEM data." Hydrology and Earth System Sciences 17, no. 10 (October 18, 2013): 4043–60. http://dx.doi.org/10.5194/hess-17-4043-2013.
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Abstract. Increasingly, ground-based and airborne geophysical data sets are used to inform groundwater models. Recent research focuses on establishing coupling relationships between geophysical and groundwater parameters. To fully exploit such information, this paper presents and compares different hydrogeophysical inversion approaches to inform a field-scale groundwater model with time domain electromagnetic (TDEM) and electrical resistivity tomography (ERT) data. In a sequential hydrogeophysical inversion (SHI) a groundwater model is calibrated with geophysical data by coupling groundwater model parameters with the inverted geophysical models. We subsequently compare the SHI with a joint hydrogeophysical inversion (JHI). In the JHI, a geophysical model is simultaneously inverted with a groundwater model by coupling the groundwater and geophysical parameters to explicitly account for an established petrophysical relationship and its accuracy. Simulations for a synthetic groundwater model and TDEM data showed improved estimates for groundwater model parameters that were coupled to relatively well-resolved geophysical parameters when employing a high-quality petrophysical relationship. Compared to a SHI these improvements were insignificant and geophysical parameter estimates became slightly worse. When employing a low-quality petrophysical relationship, groundwater model parameters improved less for both the SHI and JHI, where the SHI performed relatively better. When comparing a SHI and JHI for a real-world groundwater model and ERT data, differences in parameter estimates were small. For both cases investigated in this paper, the SHI seems favorable, taking into account parameter error, data fit and the complexity of implementing a JHI in combination with its larger computational burden.
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Stannard, David, Jayson Meyers, and Angelo Scopel. "The Abra sedimentary-hosted Pb-Ag-Cu-Au deposit, Western Australia: A geophysical case study." Leading Edge 40, no. 2 (February 2021): 129–38. http://dx.doi.org/10.1190/tle40020129.1.
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Abra is a high-grade sedimentary-hosted Pb deposit located in the Paleoproterozoic Edmund Basin in Western Australia. Mineralization is blind, with the top of the deposit occurring 250 m beneath the land surface. The deposit consists of a stratiform apron of Pb-Ag-Ba mineralization in laminated iron-oxide- and barite-altered dolomite and siltstone, which overlies a feeder zone of chlorite-altered, brecciated, and veined carbonatic siltstone that contains Pb-Ag mineralization in the core that transitions to Pb-Cu and Cu-Au at depth. Abra is characterized by discrete geophysical anomaly responses in magnetic, gravity, time-domain electromagnetic (TDEM), and induced polarization survey data. A +450 nT magnetic anomaly is caused by magnetite in the lower stratiform zone. Dense galena, barite, dolomite, and iron-oxide mineralization in the apron and galena in the feeder zone is surrounded by lower-density sedimentary host rocks, which results in a +1 mGal gravity anomaly. Airborne, ground, and downhole TDEM surveying resolved known mineralization as weak electromagnetic conductor responses, and petrophysical testing on core samples shows that this is caused by galena. Pole-dipole-induced polarization surveying resolved a +20 ms chargeability anomaly on the southern flank of the deposit. This chargeable anomaly response is related to disseminated galena, pyrite, chalcopyrite, and alteration. Joint audiomagnetotelluric-magnetotelluric 2D inverted data sections resolved Abra as a broad weakly conductive anomaly. Weak conductor responses associated with Abra were also resolved in 2D and 3D inversion modeling of airborne Z-axis tipper electromagnetic data. 2D seismic reflection surveying resolved Abra as strong flat-lying seismic reflectors, which are bounded and offset by faults and surrounded by a seismically bland zone. The seismic reflections are related to significant density contrasts between high-density stratiform mineralization that is in contact with low-density sedimentary host rocks, as the mineralization and host rocks have similar seismic velocities. Passive seismic horizontal to vertical spectral ratio surveying resolved the top of the deposit as a subtle layer sitting below a flat impedance contrast horizon that is interpreted as weathered siltstone on top of diagenetically cemented siltstone.
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Herckenrath, D., G. Fiandaca, E. Auken, and P. Bauer-Gottwein. "Sequential and joint hydrogeophysical inversion using a field-scale groundwater model with ERT and TDEM data." Hydrology and Earth System Sciences Discussions 10, no. 4 (April 11, 2013): 4655–707. http://dx.doi.org/10.5194/hessd-10-4655-2013.
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Abstract. Increasingly, ground-based and airborne geophysical datasets are used to inform groundwater models. Recent research focuses on establishing coupling relationships between geophysical and groundwater parameters. To fully exploit such information, this paper presents and compares a joint hydrogeophysical inversion (JHI) approach and sequential hydrogeophysical inversion (SHI) approach to inform a field-scale groundwater model with Time Domain Electromagnetic (TDEM) and Electrical Resistivity Tomography (ERT) data. The implemented SHI coupled inverted geophysical models with groundwater parameters, where the strength of the coupling was based on geophysical parameter resolution. To test whether the implemented SHI over- or underestimated the coupling strength between groundwater and geophysical model, we compared its results with a JHI in which a geophysical model is simultaneously inverted with a groundwater model using additional coupling constraints that explicitly account for an established petrophysical relationship and its accuracy. The first set of simulations for a synthetic groundwater model and TDEM data, employing a high-quality petrophysical and geometric relationship, showed improved estimates for groundwater model parameters that were coupled to relative well-resolved geophysical parameters. Compared to a SHI these improvements were insignificant and geophysical parameter estimates became slightly worse. In a second set of simulations, employing a low-quality petrophysical relationship, groundwater parameter improved less for both the SHI and JHI, where the SHI performed slightly better. For a real-world groundwater model and ERT data, different parameter estimates were obtained with a JHI and SHI. Parameter uncertainty was reduced but was similar for the SHI and JHI. The geometric constraint showed little impact while the petrophysical constraint showed significant changes in geophysical and groundwater parameters. For both cases investigated in this paper, the SHI seems favorable, taking in account parameter error, data fit and the complexity of implementing a JHI in combination with its larger computational burden.
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Foley, Neil, Slawek Tulaczyk, Esben Auken, Cyril Schamper, Hilary Dugan, Jill Mikucki, Ross Virginia, and Peter Doran. "Helicopter-borne transient electromagnetics in high-latitude environments: An application in the McMurdo Dry Valleys, Antarctica." GEOPHYSICS 81, no. 1 (January 1, 2016): WA87—WA99. http://dx.doi.org/10.1190/geo2015-0186.1.
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The McMurdo Dry Valleys are a polar desert in coastal Antarctica, where glaciers, permafrost, ice-covered lakes, and ephemeral summer streams coexist. Liquid water is found at the surface only in lakes and in the temporary streams that feed them. Past geophysical exploration has yielded ambiguous results regarding the presence of subsurface water. In 2011, we used a helicopter-borne, time-domain electromagnetic (TDEM) sensor to map resistivity in the subsurface across the Dry Valleys. The airborne electromagnetic (AEM) method excels at finding subsurface liquid water in polar deserts, where water remains liquid under cold conditions if it is sufficiently saline, and therefore electrically conductive. Over the course of 26 h of helicopter time, we covered large portions of the Dry Valleys and vastly increased our geophysical understanding of the subsurface, particularly with respect to water. Our data show extensive subsurface low-resistivity layers approximately 150–250 m below the surface and beneath higher resistivity layers. We interpret the low-resistivity layers as geologic materials containing freeze-concentrated or “cryoconcentrated” hyper saline brines lying beneath glaciers and frozen permafrost. These brines appeared to be contiguous with surface lakes, subglacial regions, and the Ross Sea, which could indicate a regional-hydrogeologic system, wherein solutes might be transported between surface reservoirs by ionic diffusion and subsurface flow. The presence of such brines underneath glaciers might have implications for glacier movement. Systems such as this, where brines exist beneath glacial ice and frozen permafrost, may exist elsewhere in coastal Antarctica; AEM resistivity is an ideal tool to find and survey them. Our application of TDEM demonstrates that in polar subsurface environments containing conductive brines, such a diffusive electromagnetic method is superior to radar surveying in terms of depth of penetration and ability to differentiate hydrogeologic conditions.
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Gaucher, Frédéric E. S., and Richard S. Smith. "The impact of magnetic viscosity on time-domain electromagnetic data from iron oxide minerals embedded in rocks at Opemiska, Québec, Canada." GEOPHYSICS 82, no. 5 (September 1, 2017): B165—B176. http://dx.doi.org/10.1190/geo2017-0153.1.
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The magnetic viscosity (MV) effects observed at time scales between 0.01 and 10 ms at Opemiska are associated with magnetic grains of variable size in rocks. Recent observations made during a ground time-domain electromagnetic (TDEM) survey at Opemiska are consistent with four aspects of the spatial and amplitude characteristics of a MV response: (1) the [Formula: see text] decay rate is roughly proportional to [Formula: see text], where [Formula: see text], (2) the anomalies are mainly visible on the [Formula: see text]-component, when the EM receiver sensor is located inside or just outside the transmitter loop, (3) there is no obvious [Formula: see text]- or [Formula: see text]-component response, and (4) the sites where MV effects are seen in the TDEM data are coincident with an airborne magnetic anomaly. Previous studies have demonstrated that MV could be caused by (1) fine-grained particles of maghemite or magnetite in the overburden, regolith, or soil that were formed through lateritic weathering processes, (2) volcanic glass shards from tuff containing approximately 1% by weight magnetite, which occur as grains approximately [Formula: see text] in size precipitated in a spatially uniform way, or (3) from the Gallionella bacterium that precipitates ferrihydrite that oxidizes to nanocrystalline maghemite aggregates. The sites investigated at Opemiska are outcropping and well-exposed with relatively little or no overburden, and they are unfavorable for the formation of maghemite; hence, it is assumed that the source of MV seen at Opemiska cannot be the maghemite, or the other aforementioned causes. Hand samples were collected from Opemiska to identify the minerals present. Polished thin sections observed under an optical reflecting microscope identified the accessory minerals magnetite, ilmenite, and pyrrhotite, all known for their relatively high magnetic susceptibility. The use of the scanning electron microscope confirmed fine-grained magnetite grains as small as [Formula: see text]. An electromagnetic induction spectrometer confirmed the viscous nature of the susceptibility of the Opemiska samples. This suggests that MV could originate not only from fine-grained magnetite and maghemite particles located in the weathered regolith but also from other iron oxides and magnetic minerals embedded in the rock itself.
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Parshin, Alexander, Ayur Bashkeev, Yuriy Davidenko, Marina Persova, Sergey Iakovlev, Sergey Bukhalov, Nikolay Grebenkin, and Marina Tokareva. "Lightweight Unmanned Aerial System for Time-Domain Electromagnetic Prospecting—The Next Stage in Applied UAV-Geophysics." Applied Sciences 11, no. 5 (February 26, 2021): 2060. http://dx.doi.org/10.3390/app11052060.
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Nowadays in solving geological problems, the technologies of UAV-geophysics, primarily magnetic and gamma surveys, are being increasingly used. However, for the formation of the classical triad of airborne geophysics methods in the UAV version, there was not enough technology for UAV-electromagnetic sounding, which would allow studying the geological environment at depths of tens and hundreds of meters with high detail. This article describes apparently the first technology of UAV-electromagnetic sounding in the time domain (TDEM, TEM), implemented as an unmanned system based on a light multi-rotor UAV. A measuring system with an inductive sensor—an analogue of a 20 × 20 or 50 × 50 m receiving loop is towed by a UAV, and a galvanically grounded power transmitter is on the ground and connected to a pulse generator. The survey is carried out along a network of parallel lines at low altitude with a terrain draping at a speed of 7–8 m/s, the maximum distance of the UAV’s departure from the transmitter line can reach several kilometers, thus the created technology is optimal for performing detailed areal electromagnetic soundings in areas of several square kilometers. The results of the use of the unmanned system (UAS) in real conditions of the mountainous regions of Eastern Siberia are presented. Based on the obtained data, the sensitivity of the system was simulated and it was shown that the developed technology allows one to collect informative data and create geophysical sections and maps of electrical resistivity in various geological situations. According to the authors, the emergence of UAV-TEM systems in the near future will significantly affect the practice of geophysical work, as it was earlier with UAV-magnetic prospecting and gamma-ray survey.
Dissertations / Theses on the topic "Airborne TDEM"
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Sab, Guillaume-Alexandre. "Étude de faisabilité d’un dispositif TDEM aéroporté sur avion léger dans une perspective multi-capteurs." Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066654.
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L’électromagnétisme en domaine de temporel (TDEM) permet de déterminer la variation de la résistivité du sous-sol en fonction de la profondeur. Cette méthode possède aujourd’hui deux variantes aéroportées, héliportée ou fixée sur de gros avions, qui ont l’inconvénient d’être coûteuses et de manquer pour l’une d’autonomie de vol, pour l’autre de résolution. Cette thèse CIFRE accompagne le projet TEMas (Transient ElectroMagnetic airborne system) dédié à la mise au point d’un système ultraléger tracté par petit avion avec pour objectif de disposer d’une solution peu couteuse apportant autonomie et résolution. Le cœur du travail porte sur une analyse de la sensibilité du dispositif envisagé aux principaux paramètres (géométrie, caractéristiques du signal d’émission,…) pour établir ses principales spécifications avant fabrication par les partenaires du consortium du projet TEMas. Les simulations ont porté sur différents contextes géologiques et hydrogéologiques, favorables ou non à leur caractérisation par la méthode TDEM en 1D ou en 3D (par une formulation semi analytique et par la méthode des moments). Une originalité de ce travail a été de traiter le cas de la configuration VCP (Vertical CoPlanar) dans un dispositif aéroporté TDEM. Un intérêt particulier a été porté aux contextes rencontrés sur les sites de stockage et sur le bassin de l’Orgeval (Seine et Marne). Parallèlement à ces simulations numériques, une partie de ce travail de thèse est consacrée aux aspects technologiques concernant la fabrication du dispositif, sa géométrie, le type de câble, les éléments rayonnant (boucles d’émission et réception), les matériaux utilisés et les adaptations d’impédanceTime domain electromagnetism (TDEM) allows geophysicists to probe the resistivity of the subsurface as a function of depth. Today the airborne versions of this method can be brought into operation either by helicopter or by large airplanes (fixed wings), both are expensive and the first has the disadvantage of a low autonomy (distance available after take-off), the second of a low resolution. This thesis defends the development of a light system towed by a small airplane allowing both autonomy and resolution while being more affordable. It presents numerical simulations to determine the optimal acquisition parameters (emission waveform, altitude) of the future system. Using these parameters, simulations are also performed to assess the sensitivity of the system in various geological contexts (karst and alluvial deposits) with 1D (tabular) and 3D structure. Both HCP (standard) and VCP configurations are considered. The VCP configuration greatly increases the sensitivity to 3D bodies. A special consideration is afforded to underground storage cases and to the Orgeval (subsidiary of the Seine) hydrologic basin. We also detail the (sometimes problematic) choice of the mechanical and electronic characteristics of the system, such as antenna materials selection, antenna geometries, adaptation of impedance of the transmitting and receiving coils or cable lengths and weights. This approach results in the definition of a complete TDEM system ready for future flight tests
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Reninger, Pierre-Alexandre. "Méthodologie d'analyse de levés électromagnétiques aéroportés en domaine temporel pour la caractérisation géologique et hydrogéologique." Phd thesis, Université d'Orléans, 2012. http://tel.archives-ouvertes.fr/tel-00802341.
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Cette thèse doctorale aborde divers aspects méthodologiques de l‟analyse de levés électromagnétiques aéroportés en domaine temporel (TDEM) pour une interprétation détaillée à finalités géologique et hydrogéologique. Ce travail s‟est appuyé sur un levé réalisé dans la région de Courtenay (Nord-Est de la région Centre) caractérisée par un plateau de craie karstifié (karst des Trois Fontaines) recouvert par des argiles d‟altération et des alluvions. Tout d‟abord, une méthode de filtrage des données TDEM utilisant la Décomposition en Valeurs Singulières (SVD) a été développée. L‟adaptation rigoureuse de cette technique aux mesures TDEM a permis de séparer avec succès les bruits, qui ont pu être cartographiés, et le " signal géologique ", diminuant grandement le temps nécessaire à leur traitement. De plus, la méthode s‟est avérée efficace pour obtenir, rapidement, des informations géologiques préliminaires sur la zone. Ensuite, une analyse croisée entre le modèle de résistivité obtenu en inversant les données filtrées et les forages disponibles a été effectuée. Celle-ci a mené à une amélioration de la connaissance géologique et hydrogéologique de la zone. Une figure d‟ondulation, séparant deux dépôts de craie, et le réseau de failles en subsurface ont pu être imagés, apportant un cadre géologique au karst des Trois Fontaines. Enfin, une nouvelle méthode combinant l‟information aux forages et les pentes issues du modèle de résistivité EM a permis d‟obtenir un modèle d‟une précision inégalée du toit de la craie. L‟ensemble de ces travaux fournit un cadre solide pour de futures études géo-environnementales utilisant des données TDEM aéroportées, et ce, même en zone anthropisée.
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Justina, Fabiano Della. "Estudo das variações diurnas de radiação gama atmosférica e sua interferência em levantamentos de espectrometria gama aerotransportada." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-18122012-154942/.
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As concentrações de urânio equivalente, tório equivalente, potássio e taxa de exposição foram determinadas em diferentes dias e horários para um mesmo local, a partir de dados gamaespectrométricos aerotransportados, medidos a uma altura média de 81 metros. Os perfis individuais foram então comparados com os perfis médios de todas as medidas. Os efeitos do radônio atmosférico e dos seus produtos de decaimento foram corrigidos com um pacote de cristais detectores extras voltados para cima, e os valores de calibração desses foram determinados a partir dos dados dos testes de radiação gama atmosférica: medidas acima de 760 metros de altura. A influência da radioatividade dos solos e rochas nos detectores voltados para cima foi corrigida de acordo com a técnica desenvolvida por Grasty e Hovgaard (1996) e discutida para as duas situações que elas são propostas.The concentration of equivalent uranium, equivalent thorium, potassium and exposure rate were calculated on different days and hours for the same location, from airborne gamma ray spectrometric data, measured at an average height of 81 meters. The individual profiles were compared with mean profiles of all the measurements. The effects of atmospheric radon and its decay products were corrected using a pack of additional detectors crystals facing up (upward looking detector), and the calibration values these were determined from test data of atmospheric gamma radiation: measurements above 760 meters in height. The influence of radioactivity in soil and rocks in the upward looking detector was corrected according to the technique developed by Grasty and Hovgaard (1996) and discussed the two situations for which they are proposed.
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Barroso, Diego Prado. "Processamento e interpretação de dados aeromagnéticos do Maciço Alcalino Ponte Nova (SP-MG)." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-10012019-143130/.
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O Maciço Alcalino máfico-ultramáfico Ponte Nova localiza-se no setor norte da Província Serra do Mar, junto à porção oriental da Serra da Mantiqueira, na fronteira dos Estados de São Paulo e Minas Gerais. Caracteriza-se por dois afloramentos de áreas 5 km² e 1 km². Dados magnéticos obtidos dos aerolevantamentos realizados para a CPRM pela Microsurvey Aerogeofísica e Consultoria Científica Ltda evidenciaram a presença de uma anomalia magnética extensa e de grande amplitude sobre os afloramentos. Este trabalho apresenta os resultados da interpretação geofísica e de modelagem direta integrando os dados aeromagnéticos com dados geológicos e gravimétricos do maciço visando uma caracterização do maciço em subsuperfície. Para uma determinação mais eficaz da localização e das dimensões da fonte da anomalia magnética, foram utilizadas técnicas de redução ao polo, amplitude do sinal analítico da anomalia magnética de campo total e aplicação de derivadas direcionais. Em laboratório, foram medidas as susceptibilidades magnéticas e intensidade da magnetização remanente natural de 14 amostras retiradas da região. Os resultados confirmaram a presença de magnetização remanescente em algumas das amostras, e susceptibilidade magnética média da ordem de 10-2 SI. A partir da conjunção dos dados do aerolevantamento e de dados geológicos, foi feita a modelagem direta 3-D com as propriedades magnéticas parametrizadas pelas medidas em laboratório. Os modelos consideraram a discriminação das fácies petrográficas do maciço, com susceptibilidades magnéticas variando de 0,1 a 0,9 SI. Os corpos modelados atingiram profundidades da base de pelo menos 3 km e seus volumes foram da ordem de 25 km³. Com base nas dimensões obtidas nos modelos magnéticos diretos, foi realizado um modelo gravimétrico direto com valores de densidade variando entre 2,77 g/cm³ e 3,30 g/cm³. Os resultados obtidos pelos modelos diretos foram discutidos e comparados com o modelo geológico e com outros modelos gravimétricos desenvolvidos. Apesar dos resultados alcançados pelos modelos apresentarem valores compatíveis com os observados nos levantamentos, os modelos não permitiram discriminar entre as duas hipóteses de trabalho sobre a configuração do maciço em subsuperfície: um corpo único que aflora em duas regiões ou dois corpos desconectados em subsuperfície.The Ponte Nova mafic-ultramafic alkaline massif is located in the northern sector of the Serra do Mar Province, near the eastern portion of the Serra da Mantiqueira, on the border of the states of São Paulo and Minas Gerais. It is characterized by two outcrops measuring 5 km² and 1 km² of area. Magnetic data obtained from the airborn surveys carried out for the CPRM by Microsurvey Aerogeofísica and Consultoria Científica Ltda. evidenced the presence of an extensive magnetic anomaly with great amplitude on the outcrops. This work presents the results of geophysical interpretation and direct modeling integrating the aeromagnetic data with geological and gravimetric data of the massif, aiming a characterization of the massif in the subsurface. To determine a better location and shape values of the magnetic anomaly\'s source, we use pole reduction techniques, amplitude of the analytical signal of the total field magnetic anomaly and directional derivative applications. Magnetic susceptibilities and natural remanent magnetization intensity of 14 samples from the region were measured in laboratory. The results confirm the presence of remanent magnetization in some samples, and the average magnetic susceptibility about 10-2 SI. From the conjunction of the aero-survey data and the geological data, two direct 3-D model were developed with the magnetic properties parameterized by the laboratory measurements. These models considered different petrographic facies, with magnetic susceptibilities ranging from 0.1 to 0.9 SI. The modeled bodies reached depths of the base of at least 3 km and their volumes were about 25 km³. Based on the dimensions obtained from direct magnetic models, a direct gravimetric model was performed, with density values ranging from 2.77 g / cm³ and 3.30 g / cm³. The results obtained by the direct models were discussed and compared with the geological model and with other existing gravimetric models. Although the direct models yielded results compatible with those observed in the surveys, the results do not allow for discrimination of the following working hypotheses on the configuration of the subsurface massif: a single body outcropping in two regions or two bodies disconnected in the subsurface.
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Gonçalves, Débora Romano Camilo. "Avaliação do efeito da face de exposição solar sobre o crescimento de plantios comerciais de Eucalyptus sp na região sudoeste do estado de São Paulo." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-03022015-165308/.
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As regiões de cultivo de eucalipto apresentam um grande número de variações ambientais em nível microrregional, como pode ser facilmente constatado quando se observam as diferenças expressivas entre as produtividades florestais de cada área. No entanto, para se avaliar um ambiente, é necessário identificar segmentos específicos dentro de uma paisagem, tratando-se de uma propriedade florestal e, dentro desse estudo, buscar a compreensão das interações que aí se processam. Este trabalho contribui para entender o efeito da face de exposição solar no crescimento de plantios comerciais de Eucalyptus. A proposta metodológica apresentada leva em consideração o conhecimento do meio físico - tendo como base a fisiografia para distinção das faces de exposição solar- além disso, a interação dos fatores fisiográficos com os fatores biológicos são discutidos para subsidiar a tomada de decisão. A acentuada interação genótipo x ambiente presente em muitas culturas faz com que estudos de adaptabilidade a ambientes específicos sejam parte integrante dos programas de pesquisa florestal. A resposta diferenciada dos genótipos a ambientes favoráveis e desfavoráveis pode auxiliar o gestor florestal na alocação assertiva dos materiais genéticos para maximizar a produtividade. O escaneamento a laser aerotransportado, ferramenta de uso precoce no Brasil, é um sensor óptico ativo que mede a distância até os objetos-alvo e foi utilizado para a obtenção da altura das árvores. A área de estudo está localizada na região sudoeste do estado de São Paulo. Dentre as métricas disponíveis do processamento utilizou o percentil 90 de altura para estimar a altura de plantios comerciais homogêneos de Eucalyptus. Elaborou-se a análise de variância considerando um delineamento fatorial contemplando a face de exposição solar (norte e sul) e o material genético (clones comerciais), além da interação entre ambos para observar o efeito da face no crescimento em altura do povoamento. Para florestas abaixo de quatro anos de idade observou-se que os plantios de face sul cresceram menos que os da face norte. Para florestas acima de 5 anos essa diferença entre face continua, contudo, quando concluído o desdobramento da interação fatorial observou-se que os materiais genéticos plantados em face norte não diferem entre si, mas a diferença se mantém para florestas em face sul.The eucalyptus cultivation regions boast a large number of environmental variables in micro-regional level, as can easily be seen when studying the expressive differences between the productivity of each forest area. To evaluate an environment, however, it is necessary to identify specific segments within a landscape with regards to a forest property and within that landscape study to seek the understanding of the interactions that takes place in the process. This work contributes to a better understanding of the effect of the aspect on growth in commercial plantations of Eucalyptus. The methodological approach presented in this work takes into account the knowledge of the physical environment, based on physiography, for distinction of aspect on environments, in addition to showing the interaction of physiographic factors with biological factors to support the decision-making process. The sharp interaction genotype x environment present in many cultures leads to studies of adaptability to specific environments to become integral parts of forestry research programs. The differentiated response of genotypes to favorable and unfavorable environments can assist forest managers in the allocation of assertive genetic materials to maximize productivity. The airborne laser scanning, which is an early tool used in Brazil, is an active optical sensor that measures the distance to the target objects, was used to obtain the height of the trees. The study area is located in the southwestern region of the State of São Paulo in Brazil. Among the available processing metrics, it was used 90 percentiles in height to estimate the height of homogeneous commercial plantations of Eucalyptus. A variance analysis was devised considering a factorial design contemplating the aspect (North and South) and genetic material (commercial clones), besides the interaction between both to observe the effect of the exposure on the height growth of the settlement. To forests below four years of age, it was observed that the plantations of the South exposure grow less than the north exposure. For forests above five years, this difference between aspect continues, however, when the deployment of factorial interactions is done, it\'s observed that the genetic materials planted in the north exposure do not differ with each other, but the difference stands within forests in the South exposure.
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Menezes, Adriana Araujo Reis. "Fungos em bibliotecas: frequência dos gêneros em livros e elaboração de teste para avaliação da biorreceptividade em papéis." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-21102009-163833/.
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Em bibliotecas, a grande concentração de matéria orgânica, associada a uma climatização deficiente propicia um ambiente favorável ao crescimento fúngico. O objetivo deste trabalho é desenvolver um teste para detectar a biorreceptividade ao crescimento fúngico de papéis utilizados na confecção de livros. Os gêneros de fungos foram amostrados nos períodos do inverno e verão, em seis bibliotecas da Universidade de São Paulo, três com climatização artificial e três sem. Não houve diferença no número de gêneros encontrados entre as bibliotecas com e sem climatização artificial, mas o inverno mostrou maior diversidade que o verão. Os fungos Cladosporium, Aspergillus, Chaetomium e Trichoderma foram inoculados em quatro tipos de papéis e estes foram testados em câmaras com 95% e 100% de umidade relativa, a 25 oC, por 30 dias. O crescimento ou não dos fungos nos papéis foi avaliado, assim como a alteração de cor. Nas condições do teste conclui-se que o melhor crescimento ocorreu com Cladosporium, na concentração de 106cél/mL e umidade relativa de 100%.Libraries are very propitious environments for the growth of fungi. The great concentration of organic material available for these microorganisms, and often the lack of adequate ventilation or climate control, favors this situation. The main aim of this study is to develop a test to detect fungal growth bioreceptivity in papers used in books. Firstly, fungi genera where sampled in the summer and winter in six libraries of University of São Paulo, three with artificial acclimatization and three without. There was no difference in number between the libraries with and without artificial acclimatization but the diversity was higher in the winter than in the summer. Cladosporium, Aspergillus, Trichoderma and Chaetomium where inoculated in papers and tested in chambers with 95% and 100% of relative humidity, at 25°C for 30 days. The fungal growth was evaluated, as well the color alteration. The conclusion based on the tests is that the highest growth occurred with Cladosporium, with 106 cel/mL concentration and relative humidity of 100%.
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Pereira, Marcelo Luiz. "Medição, predição e análise de partículas aéreas em salas cirúrgicas." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-29012009-141031/.
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Os sistemas de condicionamento de ar exercem função importante em uma sala cirúrgica, que é proteger a ferida cirúrgica e os equipamentos estéreis dos microrganismos carreados pelo ar. Essa proteção é feita pelo controle simultâneo da movimentação e distribuição do ar, da temperatura, da umidade, da filtragem, das infiltrações de ar de outros setores, entre outros. Esses são fatores que afetam diretamente a quantidade de partículas aéreas presentes em uma sala cirúrgica. Dentro deste contexto, no presente trabalho foi desenvolvido um modelo matemático para predição da concentração de partículas em salas cirúrgicas e para determinação da importância relativa dos fatores que interferem na geração e remoção dessas partículas. O modelo proposto baseia-se no balanço de massa para o cálculo da concentração de partículas, que foi aplicado e validado com os dados obtidos em salas cirúrgicas com diferentes tipos de sistemas de condicionamento de ar. Nessas salas cirúrgicas foram realizadas medições de variáveis ambientais considerando diferentes situações que normalmente ocorrem na rotina de salas cirúrgicas. Para cada uma das condições analisadas, é proposto um determinado conjunto de parâmetros relativos ao ambiente, ao sistema de condicionamento de ar e às concentrações de partículas provenientes das diversas fontes, que são utilizados como dados de entrada no modelo. O modelo que está sendo proposto também pode ser utilizado como uma importante ferramenta para auxiliar na análise específica dos fatores que afetam tanto a geração como a remoção de partículas.Air conditioning systems exert an important function in surgical rooms, to protect the surgical wound and the sterile equipments from airborne infected particles. This protection is achieved by means of a simultaneous control of the movement and distribution of the air, of the temperature, of the humidity, of the filtering, of air infiltrations from other sections etc. Those factors directly affect the amount of airborne particles present in a surgical room. Within this context, the present work aimed to develop a mathematical model for the prediction of particle concentrations in surgical rooms and for the determination of the relative importance of the factors that interfere in the generation and removal of those particles. The proposed model, based on mass balance for the calculation of the particle concentrations, has been applied and validated with the data obtained from different types of air conditioning systems in which the measurements were carried out, as well as with different conditions that commonly occur in the routine of surgical rooms. For each one of these conditions, a certain group of relative parameters is proposed to the environment, to the air conditioning system, and to the concentrations of particles originated from the different sources, which are used as input data to the model. The proposed model can also be used as an important tool to aid in the specific analysis of the factors that affect both particle generation and removal.
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Carlos, Dionisio Uendro. ""Desenvolvimento e construção de blocos de concreto radioativo para a calibração de espectrômetros gama portáteis e aerotransportados, utilizados em exploração mineral e de hidrocarbonetos"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-31052006-085228/.
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Oito blocos transportáveis para calibração foram construídos para serem utilizados como padrões de concentração na calibração de espectrômetros gama portáteis e aerotransportados. Todo o procedimento de construção é descrito em detalhe. Os blocos, com dimensões de 1 m x 1 m x 0,30 m e massas variando entre 593 kg e 673 kg, devem a sua radioatividade à adição de diferentes quantidades de feldspato potássico (ortoclásio), caldasito e areia monazítica à massa de concreto. As concentrações de potássio, urânio e tório variam significativamente de um bloco para outro atingindo valores máximos de 5,7% de K, 45,6 ppm eU e 137 ppm eTh. A distribuição do fluxo de radiação gama proveniente da superfície dos blocos de concreto e a magnitude das heterogeneidades na concentração dos elementos radioativos foi determinada experimentalmente. Como exemplo de aplicação apresenta-se o resultado da calibração de um espectrômetro gama portátil.Eight transportable calibration pads were built in to be used as concentration standards for portable and airborne gamma spectrometers calibrations. The pads construction procedure is described in full detail. The pads, with dimensions of 1 m x 1 m x 0,30 m and masses between 593 kg and 673 kg were made radioactive by the addition of different amounts of k-feldspar, caldasite and monazitic sand to the concrete masses. The potassium, uranium and thorium concentration vary significantly in the pads, reaching maximum values of 5,7% of K, 45,6 ppm eU and 137 ppm eTh. The distribution of the gamma radiation flux from the pads surfaces and the heterogeneity magnitudes of the radioactive elements concentration were experimentally established. An example of gamma spectrometer calibration is presented.
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Conceição, Sandro Tavares. "Contaminação aérea em cabines climatizadas: processo de avaliação e análise da influência de sistema de ventilação personalizado." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-13062013-164203/.
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A disseminação de agentes infecciosos em ambientes interiores é um assunto de interesse da sociedade em geral e uma questão de saúde pública, tendo em vista os surtos recentes do vírus SARS, gripe suína, gripe aviária, etc. Em particular, o sistema com suprimento de ar individualizado têm se mostrado eficaz, atuando como barreira contra contaminação cruzada entre ocupantes. Diversas metodologias têm sido aplicadas nesses estudos, tal como gás traçador, geradores de partículas e simulação CFD, muitas vezes sem muito critério, ou com equipamentos e simulações excessivamente complexas. Neste contexto, o objetivo do presente trabalho é desenvolver um processo robusto e com menor complexidade do que os utilizados atualmente para avaliar a dispersão de contaminantes aéreos em ambientes interiores. O processo desenvolvido é aplicado em um estudo de caso onde a influência de um sistema de ventilação personalizado de cabine de aeronave é avaliado sobre a ótica da infecção cruzada. O trabalho contempla a realização de atividades de simulação computacional (CFD) e medições experimentais no ambiente interno de uma cabine de avião (mock-up), onde os campos de velocidade do ar são medidos com Velocimetria por Imagem de Partículas (PIV), partículas entre 2 e 10m são geradas com um gerador de aerossol e contadas com contadores ópticos portáteis. Obteve-se boa correlação entre os resultados numéricos e experimentais para o campo de velocidades e boa concordância qualitativa entre as contagens de partículas no experimento e nas simulações CFD Lagrangeanas. Observou-se, dentre outros aspectos, que a válvula gasper, tal como ensaiada no presente trabalho, contribui para a qualidade do ar na zona de respiração dos ocupantes sentados, promovendo um aumento nas taxas de deposição de partículas nas superfícies internas do mock-up.The indoor dispersion of infections agents still concern the society, and has become a matter of public health, taken into account the outbreak of SARS in 2003, and the recent cases of influenza strains (H1N1, avian flu, SARS, etc). The use of personalized ventilation has improved the occupants\' air quality on recent evaluations, working as a contaminant spread barrier. Different kinds of methodologies are usually applied for those studies, such as tracer gas, particle generators and CFD simulations, sometimes without adequate criteria, or applying quite complex equipment and simulation methodologies such as transient analysis. Therefore, the main objective of the present work is to develop a robust method, and if possible less complicated than the current ones, to evaluate the dispersion of indoor airborne contaminants. Moreover, one\'s intend to apply the proposed method in a case study to evaluate the influence of a personalized ventilation system to the spread of indoor air contaminants. The study is composed by CFD simulations and experimental measurements inside an aircraft cabin mock-up, where the velocity and temperature field, as well as particle concentration are measured. Particle Image Velocimetry technique is used to analyse air flow velocities. Particles from 2 to 10µm are produced with aerosol generator and injected into the cabine. Finally, particle distributions are measured with hand held optical counters to evaluate air quality at the breathing zone. Good correlation between numerical and experimental results was obtained for velocity field, and adequate qualitative agreement was obtained for concentration field. One\'s conclude the investigated personalized ventilation system has improved the air quality around occupants breathing zone, mainly by increasing the deposition rates at the internal cabin surfaces.
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Santos, Roberto Paulo Zanon dos. "Análise multivariada de dados aerogamaespectrométricos, aeromagnéticos e sensoriamento remoto como auxiliar na prospecção de minerais metálicos na região da Bacia do Camaquã-RS." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/44/44137/tde-25092014-092813/.
Full textAbstract:
O escudo Sul-riograndense tem sua importância econômica ligada às várias mineralizações de metais base e ouro como as áreas de Camaquã, Caçapava do Sul, Lavras do Sul e São Sepé. A região é objeto de estudos geológicos desde muito tempo e vários trabalhos já foram publicados a respeito, porém todos estes mostram grande complexidade tanto quanto à origem e evolução do escudo como para as ocorrências minerais nela presentes. O presente estudo utilizou um conjunto de análises multivariadas para dados aerogeofísicos e sensoriamento remoto em parte do Escudo do Rio Grande do Sul para verificar a contribuição destas técnicas para a otimização de recursos tanto financeiros quanto de tempo na execução dos projetos de pesquisa mineral naquela região. Os resultados mostraram que o uso destas técnicas contribui para a discriminação de grupos relacionados às litologias descritas para a área de pesquisa de forma muito mais clara que o uso das metodologias de forma individualizada. Embora não tenha revelado as assinaturas das ocorrências minerais pode ser utilizada para a discriminação destas dentro dos grupos formados pelas análises.The Rio Grande do Sul Shield has its economic importance connected to the diverse gold and base metals mineralization that occurs in that area, such as Camaqua Basin, Cacapava, Lavras do Sul and São Sepé granitite intrusions. The region has been the subject of geological studies for a long time and several papers have been published about it, but they show great complexity for both the origin and evolution of the Shield and the mineral occurrences in it. The present study used a set of multivariate analysis for airborne geophysics and remote sensing data in part of the Rio Grande do Sul Shield, to verify the contribution of these techniques for the optimization of time and financial resources for the implementation of projects of mineral exploration. The results confirm that their use contribute to the discrimination of groups related to the described lithology in the area in a more clearly way that using these methodologies individually. Although the signatures of mineral occurrences have not been revealed, they can be used for their discrimination, based on the groups resultant from the analysis.
Conference papers on the topic "Airborne TDEM"
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H. Stettler, E. "Airborne TDEM by He-filled balloon." In 72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010. European Association of Geoscientists & Engineers, 2010. http://dx.doi.org/10.3997/2214-4609.201400673.
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H. Stettler, Edgar. "Airborne TDEM by He-filled Balloon." In 11th SAGA Biennial Technical Meeting and Exhibition. European Association of Geoscientists & Engineers, 2009. http://dx.doi.org/10.3997/2214-4609-pdb.241.stettler_paper1.
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Sab, G.-A., C. Schamper, F. Rejiba, and A. Tabbagh. "1D and 3D Sensitivity Analysis of an Airborne VCP TDEM System." In First European Airborne Electromagnetics Conference. Netherlands: EAGE Publications BV, 2015. http://dx.doi.org/10.3997/2214-4609.201413875.
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Legault, J. M., K. Kwan, G. Plastow, Z. Han, R. Wilson, P. Roux, and C. J. S. Fourie. "Ermelo Ring Road Risk Assessment for Coal Undermining using Airborne TDEM and Ground Geophysics." In Second European Airborne Electromagnetics Conference. Netherlands: EAGE Publications BV, 2017. http://dx.doi.org/10.3997/2214-4609.201702176.
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Hodges, G., and T. Y. Chen. "Chargeability from Airborne TDEM Data - Model Studies and Field Examples." In Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics. Netherlands: EAGE Publications BV, 2015. http://dx.doi.org/10.3997/2214-4609.201413665.
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Hodges, Greg, and Tianyou Chen. "IP effect in airborne TDEM data: Model studies and field examples." In SEG Technical Program Expanded Abstracts 2014. Society of Exploration Geophysicists, 2014. http://dx.doi.org/10.1190/segam2014-1502.1.
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Kwan, Karl, Geoffrey Plastow, Jean M. Legault, Alexander Prikhodko, Nasreddine Bournas, Marta Orta, and Sharon Taylor. "Evidence and identification of SPM in airborne TDEM data from Greenland." In SEG Technical Program Expanded Abstracts 2016. Society of Exploration Geophysicists, 2016. http://dx.doi.org/10.1190/segam2016-13964204.1.
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Guillemoteau, J., P. Sailhac, and M. Béhaegel. "On three programs with different regularization of the 1D inversion of Airborne TDEM data." In EGM 2010 International Workshop. European Association of Geoscientists & Engineers, 2010. http://dx.doi.org/10.3997/2214-4609-pdb.165.c_op_21.
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Bournas, N., G. Plastow, A. Prikhodko, K. Kwan, J. Legault, P. Berardelli, and S. Taylor. "SPM Discrimination in Airborne TDEM Data - A Case Study from the Maniitsoq Area, Southwestern Greenland." In Near Surface Geoscience 2016 - First Conference on Geophysics for Mineral Exploration and Mining. Netherlands: EAGE Publications BV, 2016. http://dx.doi.org/10.3997/2214-4609.201602099.
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G. Paine, Jeffrey, S. Todd Harris, and James M. Phelan. "Assessing Groundwater Perching Horizons Using Synthetic, Ground, And Airborne Tdem Data At The Pantex Plant, Texas." In 17th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems. European Association of Geoscientists & Engineers, 2004. http://dx.doi.org/10.3997/2214-4609-pdb.186.gw06.
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