DETERMINATION OF BOUGUER DENSITY IN SHALLOW HOLES

Geophysics ◽  
1964 ◽  
Vol 29 (3) ◽  
pp. 445-446 ◽  
Author(s):  
Stephen Thyssen‐Bornemisza
Keyword(s):  
Gravity Field ◽  
Irregular Surface ◽  
Density Values ◽  
Corrective Procedures

Inherent uncertainties of conventionally determined Bouguer‐density values may seriously affect the more sophisticated interpretation of gravity field results, predominantly in areas of irregular surface lithology. To minimize the consequences of such “incorrect” density values geophysicists have introduced and suggested corrective procedures (Nettleton, 1939; Vajk, 1956; Grant and El Saharty, 1962; Thyssen‐Bornemisza and Stackler, 1962; Hammer, 1963).

scholarly journals Strategy for the realisation of the International Height Reference System (IHRS)

2021 ◽  
Vol 95 (3) ◽  
Author(s):  
Laura Sánchez ◽  
Jonas Ågren ◽  
Jianliang Huang ◽  
Yan Ming Wang ◽  
Jaakko Mäkinen ◽  
...  
Keyword(s):  
Gravity Field ◽  
Reference System ◽  
International Association ◽  
Accuracy Assessment ◽  
Equipotential Surface ◽  
Precise Determination ◽  
Gravity Models ◽  
Reference Network ◽  
Global Gravity Models

AbstractIn 2015, the International Association of Geodesy defined the International Height Reference System (IHRS) as the conventional gravity field-related global height system. The IHRS is a geopotential reference system co-rotating with the Earth. Coordinates of points or objects close to or on the Earth’s surface are given by geopotential numbersC(P) referring to an equipotential surface defined by the conventional valueW0 = 62,636,853.4 m2 s−2, and geocentric Cartesian coordinatesXreferring to the International Terrestrial Reference System (ITRS). Current efforts concentrate on an accurate, consistent, and well-defined realisation of the IHRS to provide an international standard for the precise determination of physical coordinates worldwide. Accordingly, this study focuses on the strategy for the realisation of the IHRS; i.e. the establishment of the International Height Reference Frame (IHRF). Four main aspects are considered: (1) methods for the determination of IHRF physical coordinates; (2) standards and conventions needed to ensure consistency between the definition and the realisation of the reference system; (3) criteria for the IHRF reference network design and station selection; and (4) operational infrastructure to guarantee a reliable and long-term sustainability of the IHRF. A highlight of this work is the evaluation of different approaches for the determination and accuracy assessment of IHRF coordinates based on the existing resources, namely (1) global gravity models of high resolution, (2) precise regional gravity field modelling, and (3) vertical datum unification of the local height systems into the IHRF. After a detailed discussion of the advantages, current limitations, and possibilities of improvement in the coordinate determination using these options, we define a strategy for the establishment of the IHRF including data requirements, a set of minimum standards/conventions for the determination of potential coordinates, a first IHRF reference network configuration, and a proposal to create a component of the International Gravity Field Service (IGFS) dedicated to the maintenance and servicing of the IHRS/IHRF.

Orbit determination of the SELENE satellites using multi-satellite data types and evaluation of SELENE gravity field models

2011 ◽  
Vol 85 (8) ◽  
pp. 487-504 ◽  
Author(s):  
S. Goossens ◽  
K. Matsumoto ◽  
D. D. Rowlands ◽  
F. G. Lemoine ◽  
H. Noda ◽  
...  
Keyword(s):  
Gravity Field ◽  
Satellite Data ◽  
Orbit Determination ◽  
Data Types ◽  
Gravity Field Models

Determination of Polar Motion and Earth Rotation from Laser Tracking of Satellites

1979 ◽  
Vol 82 ◽  
pp. 231-238 ◽  
Author(s):  
David E. Smith ◽  
Ronald Kolenkiewicz ◽  
Peter J. Dunn ◽  
Mark Torrence
Keyword(s):  
Gravity Field ◽  
Radiation Pressure ◽  
Orbit Determination ◽  
Earth Rotation ◽  
Polar Motion ◽  
Ocean Tides ◽  
Earth’S Gravity Field ◽  
Laser Tracking ◽  
Order Of Magnitude

Laser tracking of the Lageos spacecraft has been used to derive the position of the Earth's pole of rotation at 5-day intervals during October, November and December 1976. The estimated precision of the results is 0.01 to 0.02 arcseconds in both x and y components, although the formal uncertainty is an order of magnitude better, and there is general agreement with the Bureau International de l'Heure smoothed pole path to about 0.02 arcseconds. Present orbit determination capability of Lageos is limited to about 25 cm rms fit to data over periods of 5 days and about 50 cm over 50 days. The present major sources of error in the perturbations of Lageos are Earth and ocean tides followed by the Earth's gravity field, and solar and Earth reflected radiation pressure. Ultimate accuracy for polar motion and Earth rotation from Lageos after improved modeling of the perturbing forces appears to be of order ± 5 cm for polar motion over a period of about 1 day and about ± 0.2 to ± 0.3 milliseconds in U.T. for periods up to 2 or 3 months.

Determination of Celestial Body Principal Axes via Gravity Field Estimation

2017 ◽  
Vol 40 (12) ◽  
pp. 3050-3060
Author(s):  
Yu Takahashi ◽  
Nicholas Bradley ◽  
Brian Kennedy
Keyword(s):  
Celestial Body ◽  
Gravity Field ◽  
Principal Axes ◽  
Field Estimation

Methodology for Measurement of Density of Liquid Oxides

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Jan Hrbek ◽  
Bence Mészáros ◽  
Mykhaylo Paukov ◽  
Martin Kudláč
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Extreme Conditions ◽  
Nuclear Accidents ◽  
System A ◽  
Different Temperatures ◽  
Density Values ◽  
Properties Of Materials ◽  
The Difference

Abstract Measurement of physical properties of materials in extreme conditions, such as high temperature, is limited by technological challenges. Nevertheless, modeling of several phenomena relies on the existence of experimental data for their validation. In this study, a method suitable for determination of density in a liquid phase at high temperature is proposed and tested on Al2O3–ZrO2 system. A methodology for acquiring the temperature dependence of density for radioactive materials is proposed and is aimed to refine severe nuclear accidents modeling. The oxide was melted in an induction furnace with a cold crucible. The measurement was based on evaluation of the volume of the melt at different temperatures, in a range from 2100 to 2400 °C. The densities of the oxide in the solid-state and the skull-layer were measured using a pycnometer. A temperature dependence of the density was established and the results were compared with literature. The difference between existing data and the measured values in this work was less than 5%. Thus, the proposed methodology provides reliable density values in extreme conditions.

Estimation of gravitational curvature through a deterministic approach and spectral combination of space-borne second-order gravitational potential derivatives

2020 ◽  
Vol 224 (2) ◽  
pp. 825-842
Author(s):  
Mohsen Romeshkani ◽  
Mohammad A Sharifi ◽  
Dimitrios Tsoulis
Keyword(s):  
Gravity Field ◽  
Ocean Circulation ◽  
Gravitational Potential ◽  
Vertical Component ◽  
Second Order ◽  
Combination Method ◽  
Deterministic Approach ◽  
Third Order ◽  
Satellite Altitude

SUMMARY Second- and third-order gravitational potential derivatives can be employed for the determination of the medium- and high-frequency parts of the Earth's gravity field. Due to the Gravity field and steady-state Ocean Circulation Explorer mission, second-order derivatives (SOD) in particular, express currently observed functionals of high accuracy and global coverage. Third-order derivatives (TOD), or gravitational curvature data, provide significant gravity field information when applied regionally. The absence of directly observed TOD data underlines the importance of investigating the relationship between SOD and TOD. This paper discusses the combination of simulated SOD in order to obtain TOD at satellite altitude by applying the spectral combination method. For the determination of TOD integral equations are developed that utilize SOD data at satellite altitude, thus extending the well-known Meissl spectral scheme. The performance of the derived mathematical models is investigated numerically for the test area of Himalayas and the Tibet region. Two different TOD computational strategies are examined. First, we define a deterministic approach that recovers TOD data from noise-free simulated SOD data. Results show that retrieved TOD data at satellite level reach an agreement of the level of 1 × 10−17 m−1s−2 when compared with the true TOD data. Secondly, we propose a new mathematical model based on the spectral combination of integral relations and noisy SOD data with Gaussian noise for recovering TOD. Integral estimators of biased and unbiased types are examined in the cases of SOD data at satellite altitude. The used vertical SOD components show differences between the recovered and true vertical TOD components in the order of 1 × 10−17 m−1s−2 in magnitude, proving the vertical–vertical component of SOD as the best for validating purposes.

scholarly journals Simulation study for the determination of the lunar gravity field from PRARE-L tracking onboard the German LEO mission

2008 ◽  
Vol 42 (8) ◽  
pp. 1405-1413 ◽  
Author(s):  
Frank Flechtner ◽  
Karl Hans Neumayer ◽  
Jürgen Kusche ◽  
Wolfgang Schäfer ◽  
Frank Sohl
Keyword(s):  
Gravity Field ◽  
Simulation Study ◽  
Lunar Gravity ◽  
Lunar Gravity Field
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