Articles de revues : « 3D gravity model »

1

Zapata, José A. « Continuum spin foam model for 3d gravity ». Journal of Mathematical Physics 43, n^o 11 (novembre 2002) : 5612–23. http://dx.doi.org/10.1063/1.1509850.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

2

Sedrakyan, A. G. « 3D Ising model and 2D induced gravity ». Physics Letters B 260, n^o 1-2 (mai 1991) : 45–52. http://dx.doi.org/10.1016/0370-2693(91)90967-u.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

3

Sun, Siyuan, Changchun Yin et Xiuhe Gao. « 3D Gravity Inversion on Unstructured Grids ». Applied Sciences 11, n^o 2 (13 janvier 2021) : 722. http://dx.doi.org/10.3390/app11020722.

Texte intégral

Résumé :

Compared with structured grids, unstructured grids are more flexible to model arbitrarily shaped structures. However, based on unstructured grids, gravity inversion results would be discontinuous and hollow because of cell volume and depth variations. To solve this problem, we first analyzed the gradient of objective function in gradient-based inversion methods, and a new gradient scheme of objective function is developed, which is a derivative with respect to weighted model parameters. The new gradient scheme can more effectively solve the problem with lacking depth resolution than the traditional inversions, and the improvement is not affected by the regularization parameters. Besides, an improved fuzzy c-means clustering combined with spatial constraints is developed to measure property distribution of inverted models in both spatial domain and parameter domain simultaneously. The new inversion method can yield a more internal continuous model, as it encourages cells and their adjacent cells to tend to the same property value. At last, the smooth constraint inversion, the focusing inversion, and the improved fuzzy c-means clustering inversion on unstructured grids are tested on synthetic and measured gravity data to compare and demonstrate the algorithms proposed in this paper.

Styles APA, Harvard, Vancouver, ISO, etc.

4

Wang, Peng, Jie Zhang et Ning Huang. « An Idealized 3D Model of Interfacial Instability of Aeolian Bedform ». Applied Sciences 11, n^o 19 (26 septembre 2021) : 8956. http://dx.doi.org/10.3390/app11198956.

Texte intégral

Résumé :

An idealized morphodynamic model is constructed for formation of the aeolian sand ripples from small bottom perturbations of a two-dimensional sand bed. The main goal of the analysis is to evaluate the influence of the gravity flow (including “impact-induced gravity flow” in the reptation flux and “topography-induced gravity flow” in the creep flux) on the formation of the aeolian sand ripples and to clarify the relative contribution of various factors to the bed instability. A 3D linear stability analysis reveals that gravity flow appreciably affects the dynamics behaviors of aeolian sand ripples, which decreases the growth rate of sand ripples, tends to stabilize the sand bed, and leads to longer wavelength. We found that the competition between the destabilizing effect of reptation flow and the stabilizing effects of gravity flow leads to pattern selection. The along-crest diffusion of topography driven by impact and gravity is beneficial to the transverse stability of sand ripples, producing sand ripples with straighter and more continuous crests. For moderate values of D, the most unstable mode has zero value of the transverse wavenumber (ky = 0), thus corresponding to aeolian ripples with crests perpendicular to the wind. Moreover, when the impact angle is 9–16°, it has little effect on the characteristics of sand ripples for the initial stage of ripple development. For every increase of the impact angle by 1°, the initial wavelength only increases by about 1.5%. In conclusion, the influence of the gravity flow on the dynamics of sand ripples formation stage cannot be neglected.

Styles APA, Harvard, Vancouver, ISO, etc.

5

BOULATOV, D. V. « A MODEL OF THREE-DIMENSIONAL LATTICE GRAVITY ». Modern Physics Letters A 07, n^o 18 (14 juin 1992) : 1629–46. http://dx.doi.org/10.1142/s0217732392001324.

Texte intégral

Résumé :

A model is proposed which generates all oriented 3D simplicial complexes weighted with an invariant associated with a topological lattice gauge theory. When the gauge group is SUq(2), qn=1, it is the Turaev-Viro invariant and the model may be regarded as a nonperturbative definition of 3D simplicial quantum gravity. If one takes a finite Abelian group G, the corresponding invariant gives the rank of the first cohomology group of a complex C:IG(C)=rank(H1(C,G)), which means a topological expansion in the Betti number b1. In general, it is a theory of the Dijkgraaf-Witten type, i.e., determined completely by the fundamental group of a manifold.

Styles APA, Harvard, Vancouver, ISO, etc.

6

ARIAS, PIO J., ADEL KHOUDEIR et J. STEPHANY. « MASTER ACTIONS FOR LINEARIZED MASSIVE GRAVITY MODELS IN 3D ». International Journal of Modern Physics A 27, n^o 03n04 (10 février 2012) : 1250015. http://dx.doi.org/10.1142/s0217751x12500157.

Texte intégral

Résumé :

We present a unified analysis of the self-dual, second order, topologically massive and the recently introduced fourth-order models of massive gravity in 3D. We show that there is a family of first-order actions which interpolate between these different single excitation models. We show how the master actions are related by duality transformation. We construct by the same method the master action which relates the fourth-order new massive model with two excitations and the usual second-order model with Fierz–Pauli mass. We show that the more general model obtained by adding a Chern–Simons term to the new massive model is equivalent off-shell to the second-order spontaneously broken linearized massive gravity.

Styles APA, Harvard, Vancouver, ISO, etc.

7

MARTELLINI, MAURIZIO, et MARIO RASETTI. « (2+1)-DIMENSIONAL QUANTUM GRAVITY AND THE 3D-ISING MODEL ». International Journal of Modern Physics B 10, n^o 18n19 (30 août 1996) : 2217–48. http://dx.doi.org/10.1142/s021797929600101x.

Texte intégral

Résumé :

We show that (2+1)-dimensional Euclidean quantum gravity is equivalent, under mild topological assumptions, to a Gaussian fermionic system. Furthermore we argue that the corresponding (2+1)-dimensional Euclidean quantum gravity partition function may be related to the partition function of the reduced 3D-lattice Ising model for finite lattices.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Chasseriau, Pierrick, et Michel Chouteau. « 3D gravity inversion using a model of parameter covariance ». Journal of Applied Geophysics 52, n^o 1 (janvier 2003) : 59–74. http://dx.doi.org/10.1016/s0926-9851(02)00240-9.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

9

Qiang, Jianke, Jing Xu, Kai Lu et Zhenwei Guo. « A Fast Forward and Inversion Strategy for Three-Dimensional Gravity Field ». Mathematics 11, n^o 4 (13 février 2023) : 962. http://dx.doi.org/10.3390/math11040962.

Texte intégral

Résumé :

Obtaining a three-dimensional (3D) density distribution within a reasonable time is one of the most critical problems in gravity exploration. In this paper, we present an efficient 3D forward modeling and inversion method for gravity data. In forward modeling, the 3D model is discretized into multiple horizontal layers, with the gravity field at a point on the surface being the sum of the gravity fields from all layers. To calculate the gravity field from each horizontal layer, we use the fast Fourier transform (FFT) method and the Block Toeplitz with Toeplitz Blocks (BTTB) matrix, which dramatically reduces both the computation time and storage requirement. In the inversion, the observed gravity data are separated into multiple gravity components of different depths using the cutting separation method. An iterative method is used to adjust the model to fit the above gravity component for each cutting radius. The initial model is constructed from the transformation of gravity components. These methods were applied to both synthetic data and field data. The numerical simulation validated the proposed methods, and the inversion results of field data were consistent with information obtained from well logging. The computational time and memory usage were also reasonable.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Geng, Meixia, Danian Huang, Qingjie Yang et Yinping Liu. « 3D inversion of airborne gravity-gradiometry data using cokriging ». GEOPHYSICS 79, n^o 4 (1 juillet 2014) : G37—G47. http://dx.doi.org/10.1190/geo2013-0393.1.

Texte intégral

Résumé :

We developed a new method for interpretation of airborne gravity gradiometry data, based on cokriging inversion. The cokriging method that we evaluated minimized the theoretical estimation error variance by using auto- and crosscorrelations of several variables. It does not require iterations and can easily include complex a priori information. Moreover, the smoothing effects in the inverted density structure model can be reduced to a certain extent due to the anisotropy constrain in the covariance model. We compared the recovered models obtained by inverting the different combinations of gravity-gradient components to understand how different component combinations contributed to the resolution of the recovered model. The results indicated that including multiple components for inversion increased the resolution of the recovered density model and improved the structure delineation. Moreover, in the case in which the parameters of the variogram model are not well chosen, cokriging with multicomponent combinations can still correctly recover the geometry of the targeted sources. The survey data of the Vinton dome were considered as a case study. The results of the inversion were in good agreement with the known formation in the region. This supports the validity of our method.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Bergshoeff, Eric, Wout Merbis, Alasdair J. Routh et Paul K. Townsend. « The third way to 3D gravity ». International Journal of Modern Physics D 24, n^o 12 (octobre 2015) : 1544015. http://dx.doi.org/10.1142/s0218271815440150.

Texte intégral

Résumé :

Consistency of Einstein’s gravitational field equation [Formula: see text] imposes a “conservation condition” on the [Formula: see text]-tensor that is satisfied by (i) matter stress tensors, as a consequence of the matter equations of motion and (ii) identically by certain other tensors, such as the metric tensor. However, there is a third way, overlooked until now because it implies a “nongeometrical” action: one not constructed from the metric and its derivatives alone. The new possibility is exemplified by the 3D “minimal massive gravity” model, which resolves the “bulk versus boundary” unitarity problem of topologically massive gravity with Anti-de Sitter asymptotics. Although all known examples of the third way are in three spacetime dimensions, the idea is general and could, in principle, apply to higher dimensional theories.

Styles APA, Harvard, Vancouver, ISO, etc.

12

Nava-Flores, Mauricio, Carlos Ortiz-Aleman, Mauricio G. Orozco-del-Castillo, Jaime Urrutia-Fucugauchi, Alejandro Rodriguez-Castellanos, Carlos Couder-Castañeda et Alfredo Trujillo-Alcantara. « 3D Gravity Modeling of Complex Salt Features in the Southern Gulf of Mexico ». International Journal of Geophysics 2016 (2016) : 1–12. http://dx.doi.org/10.1155/2016/1702164.

Texte intégral

Résumé :

We present a three-dimensional (3D) gravity modeling and inversion approach and its application to complex geological settings characterized by several allochthonous salt bodies embedded in terrigenous sediments. Synthetic gravity data were computed for 3D forward modeling of salt bodies interpreted from Prestack Depth Migration (PSDM) seismic images. Density contrasts for the salt bodies surrounded by sedimentary units are derived from density-compaction curves for the northern Gulf of Mexico’s oil exploration surveys. By integrating results from different shape- and depth-source estimation algorithms, we built an initial model for the gravity anomaly inversion. We then applied a numerically optimized 3D simulated annealing gravity inversion method. The inverted 3D density model successfully retrieves the synthetic salt body ensemble. Results highlight the significance of integrating high-resolution potential field data for salt and subsalt imaging in oil exploration.

Styles APA, Harvard, Vancouver, ISO, etc.

13

Yin, Jiang Ning, et Dun Hui Xiao. « 3D Real-Time Modeling Issue in Gravity & ; Magnetic Anomalies Interpretation Tool ». Advanced Materials Research 271-273 (juillet 2011) : 495–500. http://dx.doi.org/10.4028/www.scientific.net/amr.271-273.495.

Texte intégral

Résumé :

We present a new approach for constructing the initial 3D geological models in the process of man-machine interactive interpretation for gravity and magnetic anomalies. Firstly, we introduced the steps of method. It includes some auxiliary vertexes and sections techniques. Then, the forward algorithm of the model is given. And the data structure of the model is devised, later the modifying method and visualization method is discussed. This method is realized in our 3D gravity & magnetic anomaly interpretation system based on VC++6.0 and OpenGL. Using this method, the geophysical interpreter can construct or modify the geological models easily under the three dimension environment. The tool can give them visual 3D models, so it enhances the efficiency of the interpretation.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Zingerle, P., R. Pail, M. Scheinert et T. Schaller. « Evaluation of terrestrial and airborne gravity data over Antarctica – a generic approach ». Journal of Geodetic Science 9, n^o 1 (1 janvier 2019) : 29–40. http://dx.doi.org/10.1515/jogs-2019-0004.

Texte intégral

Résumé :

Abstract The AntGrav project, funded by the German Research Foundation (DFG) has the main objective to homogenize and optimize Antarctic gravity field information. Within this project an evaluation procedure is needed to inspect all different kind of gravity field surveys available in Antarctica. In this paper a suitable methodology is proposed. We present an approach for fast 3D gravity point data reduction in different spectral bands. This is achieved through pre-calculating a fine 3D mesh of synthesized gravity functionals over the entirety of the Antarctic continent, for which two different global models are used: the combined satellite model GOCO05s for the long-wavelength part, and the topographic model Earth2014 for the shorter wavelengths. To maximize the applicability separate meshes are calculated for different spectral bands in order to specifically reduce a certain band or a selected combination. All meshes are calculated for gravity anomalies as well as gravity disturbances. Utilizing these meshes, synthesized gravity data at arbitrary positions is computed by conventional 3D interpolation methods (e.g. linear, cubic or spline). It is shown that the applied approach can reach a worst-case interpolation error of less than 1 mGal. Evaluation results are presented for the AntGG grid and exemplary for the in-situ measurements of the AGAP and BAS-LAND campaigns. While general properties, large-scale errors and systematic effects can usually be detected, small-scale errors (e.g. of single points) are mostly untraceable due to the uncertainties within the topographic model.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Sgattoni, Giulia, et Silvia Castellaro. « Combining single-station microtremor and gravity surveys for deep stratigraphic mapping ». GEOPHYSICS 86, n^o 5 (1 septembre 2021) : G77—G88. http://dx.doi.org/10.1190/geo2020-0757.1.

Texte intégral

Résumé :

Any stratigraphic reconstruction by means of surface geophysical methods is affected by the nonuniqueness of data inversion and by the resolution-depth trade-off. The combination of different geophysical techniques can reduce the number of degrees of freedom of the problem. We have focused on two low-impact single-station geophysical techniques: microtremor and gravity. These have been used by previous authors for stratigraphic mapping only by comparing the results independently. We suggest a procedure to combine microtremor and gravity data into a unique subsoil model and explore to what extent their combined use can overcome their individual weaknesses and constrain the final result. We apply the procedure to the Bolzano sedimentary basin, Northern Italy, to derive a 3D bedrock model of the basin. We use microtremor data to map the ground resonance frequencies and derive an initial 3D bedrock depth model by assuming a [Formula: see text] profile for the sediment fill. Then, we define a density model for rock and sediments and perform 3D gravity forward modeling. We then perturb the [Formula: see text] and density models and find the parameters that best fit the observed gravity anomalies. Data uncertainties are examined to explore the significance of the results. Joint use of the two techniques successfully helps interpret the stratigraphic model: Ground resonance frequencies guarantee the spatial resolution of the bedrock geometry model, whereas gravity data help constrain the frequency to depth conversion.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Filina, Irina, Nicholas Delebo, Gopal Mohapatra, Clayton Coble, Gary Harris, John Layman, Mike Strickler et Jean-Pierre Blangy. « Integration of seismic and gravity data — A case study from the western Gulf of Mexico ». Interpretation 3, n^o 4 (1 novembre 2015) : SAC99—SAC106. http://dx.doi.org/10.1190/int-2015-0050.1.

Texte intégral

Résumé :

A 3D gravity model was developed in the western Gulf of Mexico in the East Breaks and Alaminos Canyon protraction areas. This model integrated 3D seismic, gravity, and well data; it was constructed in support of a proprietary seismic reprocessing project and was updated iteratively with seismic. The gravity model was built from seismic horizons of the bathymetry, salt layers, and the acoustic basement; however, the latter was only possible to map in seismic data during the latest iterations. In addition, a deep layer representing the Moho boundary was derived from gravity and constrained by public-domain refraction data. A 3D density distribution was derived from the seismic velocity volume using a modified Gardner equation. The modification comprised imposing a depth dependency on the Gardner coefficient, which is constant in the classic Gardner equation. The modified coefficient was derived from well data in the study area and public-domain velocity-density data sets. The forward-calculated gravity response of the composed density model was then compared with the observed gravity field, and the mismatch was analyzed jointly by a seismic interpreter and a gravity modeler. Adjustments were then made to the gravity model to ensure that the resultant salt model was geologically reasonable and supported by gravity, seismic, and well data sets. The output of the gravity modeling was subsequently applied to the next phase of seismic processing. Overall, this integration resulted in a more robust salt model, which has led to significant improvements in subsalt seismic imaging. The analysis of the regional trend in the observed gravity field suggested that a stretched continental crust underlay our seismic reprocessing area, with an oceanic-continental transition zone located to the southeast of our reprocessing region.

Styles APA, Harvard, Vancouver, ISO, etc.

17

FANI, SOMAYEH, et KAMRAN KAVIANI. « FROM DIMENSIONAL REDUCTION OF 4d SPIN FOAM MODEL TO ADDING NON-GRAVITATIONAL FIELDS TO 3d SPIN FOAM MODEL ». International Journal of Geometric Methods in Modern Physics 11, n^o 01 (16 décembre 2013) : 1450002. http://dx.doi.org/10.1142/s0219887814500029.

Texte intégral

Résumé :

A Kaluza–Klein-like approach for a 4d spin foam model is considered. By applying this approach to a model based on group field theory in 4d (TOCY model), and using the Peter–Weyl expansion of the gravitational field, reconstruction of new non-gravitational fields and interactions in the action are found. The perturbative expansion of the partition function produces graphs colored with SU(2) algebraic data, from which one can reconstruct a 3d simplicial complex representing space-time and its geometry (like in the Ponzano–Regge formulation of pure 3d quantum gravity), as well as the Feynman graph for typical matter fields. Thus a mechanism for generation of matter and construction of new dimensions are found from pure gravity.

Styles APA, Harvard, Vancouver, ISO, etc.

18

Banerjee, Rabin, et Debraj Roy. « Trivial symmetries in a 3D topological torsion model of gravity ». Journal of Physics : Conference Series 405 (13 décembre 2012) : 012028. http://dx.doi.org/10.1088/1742-6596/405/1/012028.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

19

La Rocca, Michele, Claudia Adduce, Giampiero Sciortino, Allen Bateman Pinzon et Maria Antonietta Boniforti. « A two-layer, shallow-water model for 3D gravity currents ». Journal of Hydraulic Research 50, n^o 2 (12 mars 2012) : 208–17. http://dx.doi.org/10.1080/00221686.2012.667680.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

20

Zervides, Constantinos, Andrew J. Narracott, D. Rodney Hose et Patricia V. Lawford. « GRAVITY AND VENOUS VALVE BLOOD “WASH OUT” : A 3D MODEL ». Journal of Biomechanics 41 (juillet 2008) : S272. http://dx.doi.org/10.1016/s0021-9290(08)70271-9.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

21

Guryanov, R. A., S. Monkin, A. Monkin et A. Petrov. « APPROACH TO 3D ANALYSIS OF GRAVITY PTOSIS ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W4 (10 mai 2017) : 123–27. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w4-123-2017.

Texte intégral

Résumé :

The assessment of ptosis degree for rejuvenation procedures, the choice of following operation technique and evaluation of surgery result are based on subjective visual examination and surgeon’s experience. The photogrammetric scans of 25 female patients of age 20 to 55 in vertical and supine (horizontal) position of body with placing the regular marker points on the face were analyzed. For 5 patients, also the CT data was acquired and segmentation of soft tissue was performed. Four of these patients underwent SMAS-lifting, the photogrammetry scanning was repeat 6 months after the operation. Computer vision algorithms was used for markers detection on the 3D model texture, marker were projected from texture to triangular mesh. 3D mesh models were registered with user defined anatomy points and pair selection based on markers location was done. Pairs of points on vertical and horizontal 3D models were analyzed for surface tissue mobility examination. The migration vectors of each side of the face are uniformly directed upwards and laterally. The vectors are projected at the areas of so-called ligaments demonstrate no evidence in deviation from row sequences. The volume migration is strongly correlates with the age of examined patients, on the contrary the point migration moderately correlates with age in patients of 30 to 50 years old. The analysis of migration vectors before and after the SMAS-lifting revealed no significant changes in surface points’ migration. The described method allows to assess the mechanical conditions of individual face and evaluate efficacy of surgery. This approach can be used for the classification of face ptosis grade.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Silva Dias, Fernando J., Valéria C. Barbosa et João B. Silva. « 3D gravity inversion through an adaptive-learning procedure ». GEOPHYSICS 74, n^o 3 (mai 2009) : I9—I21. http://dx.doi.org/10.1190/1.3092775.

Texte intégral

Résumé :

We have developed a gravity inversion method to estimate a 3D density-contrast distribution producing strongly interfering gravity anomalies. The interpretation model consists of a grid of 3D vertical, juxtaposed prisms in the horizontal and vertical directions. Iteratively, our approach estimates the 3D density-contrast distribution that fits the observed anomaly within the measurement errors and favors compact gravity sources closest to prespecified geometric elements such as axes and points. This method retrieves the geometry of multiple gravity sources whose density contrasts (positive and negative values) are prescribed by the interpreter through the geometric element. At the first iteration, we set an initial interpretation model and specify the first-guess geometric elements and their target density contrasts. Each geometric element operates as the first-guess skeletal outline of the entire homogeneous gravity source or any of its homogeneous parts to be reconstructed. From the second iteration on, our method automatically redefines a new set of geometric elements, the associated target density contrasts, and a new interpretation model whose number of prisms increases with the iteration. The iteration stops when the geometries of the estimated sources are invariant along successive iterations. Tests on synthetic data from geometrically complex bodies and on field data collected over a mafic-ultramafic body and a volcanogenic sedimentary sequence located in the Tocantins Province, Brazil, confirmed the potential of our method in producing a sharp image of multiple and adjacent bodies.

Styles APA, Harvard, Vancouver, ISO, etc.

23

Wijanarko, Edy, et Hendra Grandis. « Gravity - Depth Regression Method for 3D Modelling of Basement Geometry ». IOP Conference Series : Earth and Environmental Science 1031, n^o 1 (1 mai 2022) : 012024. http://dx.doi.org/10.1088/1755-1315/1031/1/012024.

Texte intégral

Résumé :

Abstract Gravity method is often used to estimate the sedimentary basin configuration at the preliminary stage of oil and gas exploration. This paper aims at the determination of 3D basement topography based on gravity data and known depth at several points. The gravity-depth relationship is used to determine the initial model and to adjust the model iteratively from the residuals. The algorithm is relatively simple and fast, since it does not involve matrix inversion nor multiplication. The proposed method also allows density contrast estimation. Tests using synthetic data showed satisfactory results in both synthetic model recovery and low RMS misfit after a few iterations.

Styles APA, Harvard, Vancouver, ISO, etc.

24

Zhdanov, Michael S., Michael Jorgensen et Le Wan. « Three-Dimensional Gravity Inversion in the Presence of the Sediment-Basement Interface : A Case Study in Utah, USA ». Minerals 12, n^o 4 (6 avril 2022) : 448. http://dx.doi.org/10.3390/min12040448.

Texte intégral

Résumé :

We introduce a novel approach to three-dimensional gravity inversion in the presence of the sediment-basement interface with a strong density contrast. This approach makes it possible to incorporate the known information about the basement depth in the inversion. It also allows the user to determine the depth-to-basement in the initial inversion phase. One can then use this interface to constrain the final inversion phase. First, the inversion generates the depth-to-basement model based on the 3D Cauchy-type integral representation of the gravity field. Then, in the second phase, full 3D voxel-type inversion applies the depth-to-basement model determined in the first phase as an a priori constraint. We use this approach to the 3D inversion of the Bouguer gravity anomaly data observed in Utah, USA. The results of inversion generated a 3D density model of the top layers of the earth’s crust, including unconsolidated sediments and the top of the crystalline basement.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Shamsipour, Pejman, Denis Marcotte, Michel Chouteau et Pierre Keating. « 3D stochastic inversion of gravity data using cokriging and cosimulation ». GEOPHYSICS 75, n^o 1 (janvier 2010) : I1—I10. http://dx.doi.org/10.1190/1.3295745.

Texte intégral

Résumé :

A new application has been developed, based on geostatistical techniques of cokriging and conditional simulation, for the 3D inversion of gravity data including geologic constraints. The necessary gravity, density, and gravity-density covariance matrices are estimated using the observed gravity data. Then the densities are cokriged or simulated using the gravity data as the secondary variable. The model allows noise to be included in the observations. The method is applied to two synthetic models: a short dipping dike and a stochastic distribution of densities. Then some geologic information is added as constraints to the cokriging system. The results show the ability of the method to integrate complex a priori information. The survey data of the Matagami mining camp are considered as a case study. The inversion method based on cokriging is applied to the residual anomaly to map the geology through the estimation of the density distribution in this region. The results of the inversion and simulation methods are in good agreement with the surface geology of the survey region.

Styles APA, Harvard, Vancouver, ISO, etc.

26

Malehmir, Alireza, Hans Thunehed et Ari Tryggvason. « The Paleoproterozoic Kristineberg mining area, northern Sweden : Results from integrated 3D geophysical and geologic modeling, and implications for targeting ore deposits ». GEOPHYSICS 74, n^o 1 (janvier 2009) : B9—B22. http://dx.doi.org/10.1190/1.3008053.

Texte intégral

Résumé :

The Kristineberg mining area in the western part of the Paleoproterozoic Skellefte Ore District, northern Sweden, is well known for its base-metal and recent gold discoveries. A pilot 3D geologic model has been constructed on a crustal scale, covering an area of [Formula: see text] to depths of [Formula: see text]. Constrained 3D inverse and forward gravity modeling have been performed to confirm and refine previous modeling along seismic profiles using mainly 2.5D techniques. The 3D inverse gravity modeling was geared to generating isodensity surfaces that enclose regions within the model of anomalous density contrast. The 3D forward gravity modeling was conducted to include faulting and folding systems that are difficult to include in the inversion. The 3D geologic model supports many previous interpretations but also reveals new features of the regional geology that are important for future targeting of base-metal and gold deposits. The margins of a thick granite in the south dip steeply inward, suggesting the possibility of room to accommodate another large base-metal deposit if the granitic rocks are juxtaposed with volcanic rocks at depth. Gravity modeling also suggests the observed Bouguer gravity high within the western metasediments can be explained by a large mafic intrusion that has dioritic to tonalitic composition and no significant magnetic signature. Because mafic-ultramafic intrusions within metasediments can indicate gold, this interpretation suggests the western metasediments have a high gold potential.

Styles APA, Harvard, Vancouver, ISO, etc.

27

Dulinska, Joanna M., et Anna Galuszka. « 3D Vs. 2D Modeling of Concrete Gravity Dam Subjected to Mining Tremor ». Applied Mechanics and Materials 405-408 (septembre 2013) : 2015–19. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.2015.

Texte intégral

Résumé :

The paper indicates the role of 3D modeling of concrete gravity dams in evaluation of dynamic response of dams to mining tremors which occur in mining activity regions. 2D and 3D models of a concrete gravity dam were prepared in order to compare two-and three-dimensional analysis of the dynamic response of dam to mining shock. Firstly, values of natural frequencies obtained for 2D and 3D models occurred to be very similar, but only the 3D model allowed to predict the dam behaviour under longitudinal kinematic excitation. Secondly, the comparison of the maximal principal stresses obtained for 2D and 3D models indicates that the simplified 2D analysis underestimates the values of dynamic response on about 20 %. Three-dimensional dynamic analysis allows to assess internal stresses resulting from mining shock more precisely, since the amplitudes of ground vibrations during mining tremors are comparable in three directions.

Styles APA, Harvard, Vancouver, ISO, etc.

28

Dulinska, Joanna. « 3D vs. 2D Modeling of Concrete Gravity Dam Subjected to Mining Tremor ». Applied Mechanics and Materials 325-326 (juin 2013) : 1324–28. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.1324.

Texte intégral

Résumé :

The paper indicates the role of 3D modeling of concrete gravity dams in evaluation of dynamic response of dams to mining tremors which occur in mining activity regions. 2D and 3D models of a concrete gravity dam were prepared in order to compare two-and three-dimensional analysis of the dynamic response of dam to mining shock. Firstly, values of natural frequencies obtained for 2D and 3D models occurred to be very similar, but only the 3D model allowed to predict the dam behaviour under longitudinal kinematic excitation. Secondly, the comparison of the maximal principal stresses obtained for 2D and 3D models indicates that the simplified 2D analysis underestimates the values of dynamic response on about 20 %. Three-dimensional dynamic analysis allows to assess internal stresses resulting from mining shock more precisely, since the amplitudes of ground vibrations during mining tremors are comparable in three directions.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Hu, Shan, et Tianjun Li. « Radial quantization of the 3d CFT and the higher spin/vector model duality ». International Journal of Modern Physics A 29, n^o 26 (16 octobre 2014) : 1450147. http://dx.doi.org/10.1142/s0217751x14501474.

Texte intégral

Résumé :

We study the radial quantization of the 3dO(N) vector model. We calculate the higher spin charges whose commutation relations give the higher spin algebra. The Fock states of higher spin gravity in AdS4 are realized as the states in the 3d CFT. The dynamical information is encoded in their inner products. This serves as the simplest explicit demonstration of the CFT definition for the quantum gravity.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Zhuang, Y., et L. Wang. « ANALYSIS OF THE GRAVITY MODELS IMPACT ON LEO SATELLITE ORBIT PREDICTION ». International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVI-3/W1-2022 (22 avril 2022) : 307–13. http://dx.doi.org/10.5194/isprs-archives-xlvi-3-w1-2022-307-2022.

Texte intégral

Résumé :

Abstract. Non-spherical gravity plays a crucial role in the LEO satellite orbit determination and prediction. In recent years, several new gravity models have been proposed with more comprehensive ground and space-borne data. The impact of the gravity models has been extensively studied while its impact on the orbit prediction has not attracted enough attention. With the risen of the mega LEO constellation, new applications such as the LEO navigation requires real-time precise orbit, which increases the importance of the precise orbit prediction. In this study, we selected six popular gravity models, namely JGM3, EGM2008, EGM96, EIGEN2, GL04C, and GGM03S, and compared their performance in different LEO orbit predictions. The comparison results indicate that there is no single optimal gravity model for all LEO orbit prediction scenarios. For short-term prediction, JGM3, EGM2008, GL04C models perform better while in long-term prediction JGM3, EGM96, EIGEN2 have more potential. The results also reveal that the optimal model changed with time. In addition, the impact of the gravity order on the orbit prediction is investigated, the results indicate that for satellites with lower orbital heights, the gravitational field order required to achieve a certain truncation error is higher than for satellites with higher orbital heights. The authors also explore the effect of gravitational field-associated permanent tides on orbital prediction. In one day, for satellites with an orbital altitude of about 970km, the effect of permanent tides on 3D RMS is 6.92m; for satellites around 710km, the effect of permanent tides on 3D RMS is 4.20m; for satellites around 970km, the effect of permanent tides on 3D RMS is 2.07m.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Sun, Jiajia, Aline Tavares Melo, Jae Deok Kim et Xiaolong Wei. « Unveiling the 3D undercover structure of a Precambrian intrusive complex by integrating airborne magnetic and gravity gradient data into 3D quasi-geology model building ». Interpretation 8, n^o 4 (23 juillet 2020) : SS15—SS29. http://dx.doi.org/10.1190/int-2019-0273.1.

Texte intégral

Résumé :

Mineral exploration under a thick sedimentary cover naturally relies on geophysical methods. We have used high-resolution airborne magnetic and gravity gradient data over northeast Iowa to characterize the geology of the concealed Precambrian rocks and evaluate the prospectivity of mineral deposits. Previous researchers have interpreted the magnetic and gravity gradient data in the form of a 2D geologic map of the Precambrian basement rocks, which provides important geophysical constraints on the geologic history and mineral potentials over the Decorah area located in the northeast of Iowa. However, their interpretations are based on 2D data maps and are limited to the two horizontal dimensions. To fully tap into the rich information contained in the high-resolution airborne geophysical data, and to further our understanding of the undercover geology, we have performed separate and joint inversions of magnetic and gravity gradient data to obtain 3D density contrast models and 3D susceptibility models, based on which we carried out geology differentiation. Based on separately inverted physical property values, we have identified 10 geologic units and their spatial distributions in 3D which are all summarized in a 3D quasi-geology model. The extension of 2D geologic interpretation to 3D allows for the discovery of four previously unidentified geologic units, a more detailed classification of the Yavapai country rock, and the identification of the highly anomalous core of the mafic intrusions. Joint inversion allows for the classification of a few geologic units further into several subclasses. We have demonstrated the added value of the construction of a 3D quasi-geology model based on 3D separate and joint inversions.

Styles APA, Harvard, Vancouver, ISO, etc.

32

Chakravarthi, Vishnubhotla, et Narasimman Sundararajan. « 3D gravity inversion of basement relief — A depth-dependent density approach ». GEOPHYSICS 72, n^o 2 (mars 2007) : I23—I32. http://dx.doi.org/10.1190/1.2431634.

Texte intégral

Résumé :

We present a 3D gravity inversion technique, based on the Marquardt algorithm, to analyze gravity anomalies attributable to basement interfaces above which the density contrast varies continuously with depth. The salient feature of this inversion is that the initial depth of the basement is not a required input. The proposed inversion simultaneously estimates the depth of the basement interface and the regional gravity background. Applicability and efficacy of the inversion is demonstrated with a synthetic model of a density interface. We analyze the synthetic gravity anomalies (1) solely because of the structure, (2) in the presence of a regional gravity background, and (3) in the presence of both random noise and regional gravity background. The inverted structure remains more or less the same, regardless of whether the regional background is simulated with a second-degree polynomial or a bilinear equation. The depth of the structure and estimated regional background deviate only modestly from the assumed ones in the presence of random noise and regional background. The analyses of two sets of real field data, one over the Chintalpudi subbasin, India, and another over the Pannonian basin, eastern Austria, yield geologically plausible models with the estimated depths that compare well with drilling data.

Styles APA, Harvard, Vancouver, ISO, etc.

33

Jia, Dongdong, Jianyin Zhou, Xuejun Shao et Xingnong Zhang. « 3D Numerical Simulation of Gravity-Driven Motion of Fine-Grained Sediment Deposits in Large Reservoirs ». Water 13, n^o 13 (4 juillet 2021) : 1868. http://dx.doi.org/10.3390/w13131868.

Texte intégral

Résumé :

Deposits in dam areas of large reservoirs, which are commonly composed of fine-grained sediment, are important for reservoir operation. Since the impoundment of the Three Gorges Reservoir (TGR), the sedimentation pattern in the dam area has been unexpected. An integrated dynamic model for fine-grained sediment, which consists of both sediment transport with water flow and gravity-driven fluid mud at the bottom, was proposed. The incipient motion driven by gravity in the form of fluid mud was determined by the critical slope. Shallow flow equations were simplified to simulate the gravity-driven mass transport. The gravity-driven flow model was combined with a 3D Reynolds-averaged water flow and sediment transport model. Solution routines were developed for both models, which were then used to simulate the integral movement of the fine-grained sediment. The simulated sedimentation pattern agreed well with observations in the dam area of the TGR. Most of the deposits were found at the bottom of the main channel, whereas only a few deposits remained on the bank slopes. Due to the gravity-driven flow of fluid mud, the deposits that gathered in the deep channel formed a nearly horizontal surface. By considering the gravity-driven flow, the averaged error of deposition thickness along the thalweg decreased from −13.9 to 2.2 m. This study improved our understanding of the mechanisms of fine-grained sediment transport in large reservoirs and can be used to optimize dam operations.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Sampietro, Daniele, et Martina Capponi. « Practical Tips for 3D Regional Gravity Inversion ». Geosciences 9, n^o 8 (10 août 2019) : 351. http://dx.doi.org/10.3390/geosciences9080351.

Texte intégral

Résumé :

To solve the inverse gravimetric problem, i.e., to estimate the mass density distribution that generates a certain gravitational field, at local or regional scale, several parameters have to be defined such as the dimension of the 3D region to be considered for the inversion, its spatial resolution, the size of its border, etc. Determining the ideal setting for these parameters is in general difficult: theoretical solutions are usually not possible, while empirical ones strongly depend on the specific target of the inversion and on the experience of the user performing the computation. The aim of the present work is to discuss empirical strategies to set these parameters in such a way to avoid distortions and errors within the inversion. In particular, the discussion is focused on the choice of the volume of the model to be inverted, the size of its boundary, its spatial resolution, and the spatial resolution of the a-priori information to be used within the data reduction. The magnitude of the possible effects due to a wrong choice of the above parameters is also discussed by means of numerical examples.

Styles APA, Harvard, Vancouver, ISO, etc.

35

Bosch, Miguel, Ronny Meza, Rosa Jiménez et Alfredo Hönig. « Joint gravity and magnetic inversion in 3D using Monte Carlo methods ». GEOPHYSICS 71, n^o 4 (juillet 2006) : G153—G156. http://dx.doi.org/10.1190/1.2209952.

Texte intégral

Résumé :

We jointly invert gravity and magnetic data following a Monte Carlo method that provides estimation for a 3D model of the structure and physical properties of the medium. In particular, the model layer geometry and the density and magnetic susceptibility fields within layers are estimated, and their uncertainties are described with posterior probabilities. This method combines the gravity and magnetic data with prior information of the mass density and magnetic susceptibility statistics, and statistical constraints on the model interface positions. The resulting model realizations jointly comply with the observations and the prior statistical information.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Mendonça, Diego C. M., et Olivier Piguet. « Loop Quantization of a 3D AbelianBFModel withσ-Model Matter ». Advances in Mathematical Physics 2015 (2015) : 1–8. http://dx.doi.org/10.1155/2015/307132.

Texte intégral

Résumé :

The main goal of this work is to explore the symmetries and develop the dynamics associated with a 3D AbelianBFmodel coupled to scalar fields submitted to a sigma model like constraint, at the classical and quantum levels. Background independence, on which the model is founded, strongly constrains its nature. We adapt to the present model the techniques of Loop Quantum Gravity in order to construct its physical Hilbert space and its observables.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Peng, Guomin, et Zhan Liu. « 3D inversion of gravity data using reformulated L -norm model regularization ». Journal of Applied Geophysics 191 (août 2021) : 104378. http://dx.doi.org/10.1016/j.jappgeo.2021.104378.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

38

Oemaiya, D. V., et D. Santoso. « 3D model of Krakatau volcano subsurface structure based on gravity data ». Journal of Physics : Conference Series 1242 (juin 2019) : 012049. http://dx.doi.org/10.1088/1742-6596/1242/1/012049.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

39

Le Magoarou, Camille, Katja Hirsch, Clement Fleury, Remy Martin, Johana Ramirez-Bernal et Philip Ball. « Integration of gravity, magnetic, and seismic data for subsalt modeling in the Northern Red Sea ». Interpretation 9, n^o 2 (21 avril 2021) : T507—T521. http://dx.doi.org/10.1190/int-2019-0232.1.

Texte intégral

Résumé :

Rifts and rifted passive margins are often associated with thick evaporite layers, which challenge seismic reflection imaging in the subsalt domain. This makes understanding the basin evolution and crustal architecture difficult. An integrative, multidisciplinary workflow has been developed using the exploration well, gravity and magnetics data, together with seismic reflection and refraction data sets to build a comprehensive 3D subsurface model of the Egyptian Red Sea. Using a 2D iterative workflow first, we have constructed cross sections using the available well penetrations and seismic refraction data as preliminary constraints. The 2D forward model uses regional gravity and magnetic data to investigate the regional crustal structure. The final models are refined using enhanced gravity and magnetic data and geologic interpretations. This process reduces uncertainties in basement interpretation and magmatic body identification. Euler depth estimates are used to point out the edges of high-susceptibility bodies. We achieved further refinement by initiating a 3D gravity inversion. The resultant 3D gravity model increases precision in crustal geometries and lateral density variations within the crust and the presalt sediments. Along the Egyptian margin, where data inputs are more robust, basement lows are observed and interpreted as basins. Basement lows correspond with thin crust ([Formula: see text]), indicating that the evolution of these basins is closely related to the thinning or necking process. In fact, the Egyptian Northern Red Sea is typified by dramatic crustal thinning or necking that is occurring over very short distances of approximately 30 km, very proximal to the present-day coastline. The integrated 2D and 3D modeling reveals the presence of high-density magnetic bodies that are located along the margin. The location of the present-day Zabargad transform fault zone is very well delineated in the computed crustal thickness maps, suggesting that it is associated with thin crust and shallow mantle.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Olaniyan, Oladele, Richard S. Smith et Bruno Lafrance. « Regional 3D geophysical investigation of the Sudbury Structure ». Interpretation 3, n^o 2 (1 mai 2015) : SL63—SL81. http://dx.doi.org/10.1190/int-2014-0200.1.

Texte intégral

Résumé :

The 3D geologic and structural setting of the Sudbury Structure was predicted by an integration of surface and subsurface geologic data with 2.5D modeling of high-resolution airborne magnetic and gravity data using 3D GeoModeller software. Unlike other CAD-based 3D software, GeoModeller uses the field interpolator method, whereby contacts of rock units are assumed to be equipotential surfaces, whereas orientation data determine the gradient and direction of the surfaces. Contacts and orientation variables are cokriged to generate 3D continuous surfaces for each geologic unit. Our 3D geologic model was qualitatively evaluated by forward computing the predicted gravity response at 1 m above topography and by comparing this response to the measured gravity field. Large-scale structures within the Onaping Formation and Archean basement, which overlie and underlie the Sudbury Igneous Complex (SIC), respectively, were not the cause of the linear gravity high in the center of the Sudbury Structure. We suggested that the deformation of the initial circular SIC may have commenced under the Sudbury Basin due to the reversal of the normal faults related to the Huronian rift system during the Penokean orogeny, therefore resulting into a north verging fold at the base of the SIC in the south range. This new interpretation was consistent with the magnetic and gravity data and honoured most of the significant seismic reflectors in the Lithoprobe seismic sections.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Lü, Qingtian, Guang Qi et Jiayong Yan. « 3D geologic model of Shizishan ore field constrained by gravity and magnetic interactive modeling : A case history ». GEOPHYSICS 78, n^o 1 (1 janvier 2013) : B25—B35. http://dx.doi.org/10.1190/geo2012-0126.1.

Texte intégral

Résumé :

We performed a study on using an integrated geologic model in mineral exploration at depth. Shizishan ore field, in the western part of the Tongling ore district, Anhui Province in China, is well known for its polymetallic deposits and recent deep discovery of Dongguashan deposit at around 1000-m depth. Understanding the 3D structure and delineating the locations and variations of the intrusions and ore-controlling strata in the study area are essential for selecting deep mineral targets. A pilot 3D geologic model, covering an area of 11 × 16 km and extends to a depth of 3 km, has been constructed by interactive gravity and magnetic inversions to define the geometry, depth, and physical properties of geologic bodies at depths. The 3D visualization of the results assists in understanding the spatial relations between various intrusive units and the ore-bearing strata. The model has confirmed most previous knowledge, but also revealed new features of different folds and intrusions that are important for planning future exploration at large depths. Several deep targets have also been predicted by combining the conceptual mineralization model in the district with the 3D geologic model. Our study demonstrates the potential of using gravity and magnetic data with geologic constraints to build 3D models in structurally complex areas for the purpose of mineral exploration at depth and under cover.

Styles APA, Harvard, Vancouver, ISO, etc.

42

Martinez, Cericia, et Yaoguo Li. « Lithologic characterization using airborne gravity gradient and aeromagnetic data for mineral exploration : A case study in the Quadrilátero Ferrífero, Brazil ». Interpretation 3, n^o 2 (1 mai 2015) : SL1—SL13. http://dx.doi.org/10.1190/int-2014-0195.1.

Texte intégral

Résumé :

We present a study on utilizing airborne gravity gradient and magnetic data to characterize an iron ore formation in Minas Gerais, Brazil. The target iron ore bodies have a distinctly high density contrast and produce well-defined anomalies in airborne gravity gradiometry data. The high-grade hematite iron ores are associated with low and moderate susceptibility, making magnetic data useful in distinguishing potential ore bodies from the host iron formation. The airborne gravity gradient and magnetic data over part of the Gandarela Syncline iron formation in the Quadrilátero Ferrífero are independently inverted to obtain a 3D susceptibility and density contrast model. These detailed 3D physical property distributions of subsurface features are then used for geologic characterization and interpretation purposes through lithologic associations. We outline two approaches to link the two physical property distributions and identify representative geologic units in the study area. The geologic units are then organized into a 3D lithology model to help characterize subsurface geologic structure and ore distribution. The lithologic models provide an intuitive representation of the geology and can assist in future exploration plans or in assessment of resource distribution and quality. Our study demonstrates that such approaches are feasible on the deposit scale.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Lücke, Oscar H., Hans-Jürgen Götze et Guillermo E. Alvarado. « A Constrained 3D Density Model of the Upper Crust from Gravity Data Interpretation for Central Costa Rica ». International Journal of Geophysics 2010 (2010) : 1–9. http://dx.doi.org/10.1155/2010/860902.

Texte intégral

Résumé :

The map of complete Bouguer anomaly of Costa Rica shows an elongated NW-SE trending gravity low in the central region. This gravity low coincides with the geographical region known as the Cordillera Volcánica Central. It is built by geologic and morpho-tectonic units which consist of Quaternary volcanic edifices. For quantitative interpretation of the sources of the anomaly and the characterization of fluid pathways and reservoirs of arc magmatism, a constrained 3D density model of the upper crust was designed by means of forward modeling. The density model is constrained by simplified surface geology, previously published seismic tomography and P-wave velocity models, which stem from wide-angle refraction seismic, as well as results from methods of direct interpretation of the gravity field obtained for this work. The model takes into account the effects and influence of subduction-related Neogene through Quaternary arc magmatism on the upper crust.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Roy, Régis, Antonio Benedicto, Alexis Grare, Mickaël Béhaegel, Yoann Richard et Grant Harrison. « Three-dimensional gravity modelling applied to the exploration of uranium unconformity-related basement-hosted deposits : the Contact prospect case study, Kiggavik, northeast Thelon region (Nunavut, Canada) ». Canadian Journal of Earth Sciences 54, n^o 8 (août 2017) : 869–82. http://dx.doi.org/10.1139/cjes-2016-0225.

Texte intégral

Résumé :

In unconformity-related uranium deposits, mineralization is associated with hydrothermal clay-rich alteration haloes that decrease the density of the host rock. In the Kiggavik uranium project, located in the eastern Thelon Basin, Nunavut (Canada), basement-hosted shallow deposits were discovered by drilling geophysical anomalies in the 1970s. In 2014, gravity data were inverted for the first time using the Geosoft VOXI Earth ModellingTM system to generate three-dimensional (3D) models to assist exploration in the Contact prospect, the most recent discovery at Kiggavik. A 3D unconstrained inversion model was calculated before drilling, and a model constrained by petrophysical data was computed after drilling. The unconstrained inversion provided a first approximation of the geometry and depth of a low-density body and helped to collar the discovery holes of the Contact mineralization. The constrained inversion was computed using density values measured on 315 core samples collected from 21 drill holes completed between 2014 and 2015. The constrained modelling highlights three shallower and smaller low-density bodies that match the geological interpretation and refines the footprint of the gravity anomalies in relation to the current understanding of the deposit. The 3D inversion of gravity data is a valuable tool to guide geologists in exploration of shallow basement-hosted uranium deposits associated with alteration haloes and to assess the deposit gravity geometry.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Gan, Yong, Jing Ru Zhong et Du Fen Gan. « Research on 3D Non-Destructive Measurement System Based on Homogeneous Entity ». Advanced Materials Research 201-203 (février 2011) : 63–68. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.63.

Texte intégral

Résumé :

A new non-destructive measurement system of the homogeneous entity profiles was designed; it included the digitized minute entity cells and the delaminated measuring method for product profiles based on liquid. It is based on Archimedes' principle and lever principle and gravity moment, used optic system to collect images and calculated the verge profiles, combined the equations of the gravity moment and the equations of the center of gravity to reckon the 3D coordinate values of every minute entity cell in different layers by computer. By inputting the 3D coordinate values of the product into the related CAD software system, the 3D model could be obtained. The principles, hardware and software of the system were introduced in details about the measurement system of the homogeneous entity profiles.

Styles APA, Harvard, Vancouver, ISO, etc.

46

Wu, Tangting, Jiancheng Li, Xinyu Xu, Hui Wei, Kaifa Kuang et Yongqi Zhao. « Gravity Field Model Determination Based on GOCE Satellite Point-Wise Accelerations Estimated from Onboard Carrier Phase Observations ». Remote Sensing 11, n^o 12 (14 juin 2019) : 1420. http://dx.doi.org/10.3390/rs11121420.

Texte intégral

Résumé :

GPS-based, satellite-to-satellite tracking observations have been extensively used to elaborate the long-scale features of the Earth’s gravity field from dedicated satellite gravity missions. We proposed compiling a satellite gravity field model from Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite accelerations directly estimated from the onboard GPS data using the point-wise acceleration approach, known as the carrier phase differentiation method. First, we composed the phase accelerations from the onboard carrier phase observations based on the sixth-order seven-point differentiator, which can eliminate the carrier phase ambiguity for Low Earth Orbiter (LEO). Next, the three-dimensional (3D) accelerations of the GOCE satellite were estimated from the derived phase accelerations as well as GPS satellite ephemeris and precise clock products. Finally, a global gravity field model up to the degree and order (d/o) 130 was compiled from the 71 days and nearly 2.5 years of 3D satellite accelerations. We also recovered three gravity field models up to d/o 130 from the accelerations derived by differentiating the kinematic orbits of European Space Agency (ESA), Graz, and School of Geodesy and Geomatics (SGG), which was the orbit differentiation method. We analyzed the accuracies of the derived accelerations and the recovered gravity field models based on the carrier phase differentiation method and orbit differentiation method in time, frequency, and spatial domain. The results showed that the carrier phase derived acceleration observations had better accuracy than those derived from kinematic orbits. The accuracy of the recovered gravity field model based on the carrier phase differentiation method using 2.5 years observations was higher than that of the orbit differentiation solutions for degrees greater than 70, and worse than Graz-orbit solution for degrees less than 70. The cumulative geoid height errors of carrier phase, ESA-orbit, and Graz-orbit solutions up to degree and order 130 were 17.70cm, 21.43 cm, and 22.11 cm, respectively.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Dubey, Chandra Prakash, Hans-Jürgen Götze, Sabine Schmidt et Virendra Mani Tiwari. « A 3D model of the Wathlingen salt dome in the Northwest German Basin from joint modeling of gravity, gravity gradient, and curvature ». Interpretation 2, n^o 4 (1 novembre 2014) : SJ103—SJ115. http://dx.doi.org/10.1190/int-2014-0012.1.

Texte intégral

Résumé :

In the past few decades, numerous attempts have been made on modeling of salt tectonics and deciphering the geometry of salt domes, which is a key challenge in petroleum exploration. We have derived a 3D density model of the Wathlingen salt dome, situated in the southern part of the Northwest German Basin from joint modeling of reprocessed torsion balance measurements. Gravity, gravity gradients [Formula: see text], curvature derived from horizontal gravity gradients [Formula: see text], and horizontal directive tendency are jointly modeled to decipher the geometric structure of the salt dome. The model was constrained by geologic and borehole information. We found that the Wathlingen salt dome is a mushroom-structured salt body, which is 14-km long, 4–8-km wide extending up to [Formula: see text] depth. The top mushroom structure of the salt is horizontally spread up to [Formula: see text]. It would not have been possible to derive the complex 3D structure from modeling of gravity data alone.

Styles APA, Harvard, Vancouver, ISO, etc.

48

SOTKOV, G., C. P. CONSTANTINIDIS et U. CAMARA DS. « NEW MASSIVE GRAVITY HOLOGRAPHY ». International Journal of Modern Physics A 28, n^o 17 (10 juillet 2013) : 1350073. http://dx.doi.org/10.1142/s0217751x13500735.

Texte intégral

Résumé :

We investigate the holographic renormalization group flows and the classical phase transitions that occur in two-dimensional QFT model dual to the New Massive 3D Gravity coupled to scalar matter. Specific matter self-interactions generated by quadratic superpotential are considered. The off-critical AdS3/CFT2 correspondence determines the exact form of the QFT2's β-function and the singular part of the reduced free energy. The corresponding scaling laws and critical exponents characterizing the RG fixed points as well as the values of the mass gaps in the massive phases are obtained.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Koutchmy, S., M. Molodensky et D. Vibert. « A Model of Plasma Sheets in Equilibrium ». International Astronomical Union Colloquium 167 (1998) : 127–30. http://dx.doi.org/10.1017/s0252921100047436.

Texte intégral

Résumé :

AbstractWe consider large coronal streamers as confined thin plasma sheets overlying the filament and/or the magnetic polarity inversion lines. Confirmation is found in recent synoptic LASCO/SOHO data and simulations. We discuss the 3D axi-symmetric consistent MHD solution which provides the necessary properties of confinement and equilibrium by including gravity forces in the Grad-Shafranov equation.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Li, Ze, et Li Xiang Zhang. « Seismic Damage Analysis of RCC Gravity Dams Using 3D Nonlinear FEM ». Applied Mechanics and Materials 120 (octobre 2011) : 397–402. http://dx.doi.org/10.4028/www.scientific.net/amm.120.397.

Texte intégral

Résumé :

The earthquake-resistance performance of gravity dam is an important indicator of dam safety. The earthquake-resistance performance of non-overflow monolith for Guanyinyan gravity dam is evaluated in this paper. First of all, the three-dimensional finite element model of dam is established by ABAQUS software. And then, the seismic response of gravity dam is analyzed by nonlinear finite element method, while the concrete damage plasticity constitutive model is adopted to describe the tensile characteristic of concrete. The seismic response and the damage evolution of dam are obtained. The results show that the dam has formed a crack-like band damage area at the end of earthquake, which are located in the dam along the dam-foundation boundary near the upstream face. At last, according to the results of simulation, the safety and the damage range are investigated.

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « 3D gravity model »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres