نتایج جستجو برای: Gravity Data

تعداد نتایج: 2464280  

Journal: :فیزیک زمین و فضا 0
کیلان راست بین دانشگاه آزاد همدان سعید وطن خواه دانشگاه تهران وحید ابراهیم زاده اردستانی استاد گروه فیزیک زمین

in this paper the inversion of gravity data using l1–norm stabilizer is considered. the inversion is an important step in the interpretation of data. in gravity data inversion, the goal is to estimate density and geometry of the unknown subsurface model from a set of known observation measured on the surface. commonly, rectangular prisms are used to model the subsurface under the survey area. t...

Journal: :فیزیک زمین و فضا 0
naeim mousavi ph.d. candidate, institute of geophysics, university of tehran, tehran, iran vahid ebrahimzadeh ardestani professor, institute of geophysics, university of tehran, tehran, iran

the s-transform has widely been used in the analysis of non-stationary time series. a simple method to obtain depth estimates of gravity field sources is introduced in this study. we have developed a new method based on the spectral characteristics of downward continuation to estimate depth of structures. this calculation procedure is based on replacement of the fourier transform with the s-tra...

Journal: :فیزیک زمین و فضا 0
a safari department of surveying and geomatics engineering, university college of engineering, university of tehran, tehran, iran m.a sharifi department of surveying and geomatics engineering, university college of engineering, university of tehran, tehran, iran h amin department of surveying and geomatics engineering, university college of engineering, university of tehran, tehran, iran i foroughi department of surveying and geomatics engineering, university college of engineering, university of tehran, tehran, iran

gravity acceleration data have grand pursuit for marine applications. due to environmental effects, marine gravity observations always hold a high noise level. in this paper, we propose an approach to produce marine gravity data using satellite altimetry, high-resolution geopotential models and harmonic splines. on the one hand, harmonic spline functions have great capability for local gravity ...

Journal: :فیزیک زمین و فضا 0
وحید ابراهیم زاده اردستانی مؤسسه ژئوفیزیک دانشگاه تهران، دانشیار

micro gravity data was collected in a crowded street in tehran where a subway terrain tunnel is to be excavated. the data is corrected for the gravity effects of the surrounding densely built up area with diverse buildings and the bouguer gravity anomalies are computed. the residual gravity anomalies are prepared by removing a trend surface. upward continuation is used to remove the gravity eff...

ژورنال: فیزیک زمین و فضا 2014
A Safari H Amin I Foroughi M.A Sharifi

Gravity acceleration data have grand pursuit for marine applications. Due to environmental effects, marine gravity observations always hold a high noise level. In this paper, we propose an approach to produce marine gravity data using satellite altimetry, high-resolution geopotential models and harmonic splines. On the one hand, harmonic spline functions have great capability for local gravity ...

Estimating the gravity anomaly causative bodies boundary can facilitate the gravity field interpretation. In this paper, 2D discrete wavelet transform (DWT) is employed as a method to delineate the boundary of the gravity anomaly sources. Hence, the GRACE’ satellite gravity data is decomposed using DWT. DWT decomposites a single approximation coefficients into four distinct components: the appr...

Journal: :فیزیک زمین و فضا 0
mahnaz eskandari m.sc. graduated, department of geophysics, islamic azad university of hamedan, iran vahid ebrahimzadeh ardestani professor, department of earth physics, institute of geophysics, university of tehran, iran

one of the main goals of interpretation of gravity data is to detect location and edges of the anomalies. edge detection of gravity anomalies is carried out by different methods. terracing of the data is one of the approaches that help the interpreter to achieve appropriate results of edge detection. this goal becomes a complex task when the gravity anomalies have smooth borders due to gradual ...

Journal: :فیزیک زمین و فضا 0
عبدالرضا صفری یعقوب حاتم مهدی شاه حیدری

precise geoid determination on islands suffers from the lack of accurate gravity data on the open seas. nowadays, sub-microgal accuracy for the land gravity observations is obtainable. but the sea gravity data which are collected via shipborne techniques, due to the measuring environment at sea area, are usually highly noisy and are contaminated with various systematic errors. on the other hand...

Gravity data inversion is one of the important steps in the interpretation of practical gravity data. The inversion result can be obtained by minimization of the Tikhonov objective function. The determination of an optimal regularization parameter is highly important in the gravity data inversion. In this work, an attempt was made to use the active constrain balancing (ACB) method to select the...

Journal: :journal of mining and environment 2013
ali nejati kalateh amin roshandel kahoo

we inverse the surface gravity data to recover subsurface 3d density distribution with two strategy. in the first strategy, we assumed wide density model bound for inverting gravity data and in the second strategy, the inversion procedure have been carried out by limited bound density. wediscretize the earth model into rectangular cells of constant andunidentified density. the number of cells i...

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