Relevant bibliographies by topics / Ellipsoidal Heights

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers

Academic literature on the topic 'Ellipsoidal Heights'

Author: Grafiati
Published: 4 June 2025
Last updated: 23 June 2025

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Journal articles on the topic "Ellipsoidal Heights"

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ETEJE, S. O., P. D. OLUYORI, and M. N. ONO. "Comparison of Two Polynomial Geoid Models of GNSS/Leveling Geoid Development for Orthometric Heights in FCT, Abuja." International Journal of Engineering Research and Advanced Technology (IJERAT) 4, no. 10 (2018): 1–9. https://doi.org/10.5281/zenodo.2525684.

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Ellipsoidal heights from GNSS require geoid model for conversion to orthometric height. The geoid model could be global, regional or local. The lack of national geoid model in Nigeria makes development of local geoid very critical to local applications in place of integrated global geoid models. This study compares two polynomial geoid models for terrain representation in the FCT, Abuja. Nine coefficients were used to model the FCT surface for geoid interpolation and orthometric height modeling. Model A involved the use of the 2-D (x, y) positions while model B used 3-D (x, y, ) where = ( – ) the difference in average ellipsoidal height ( ) and each point’s ellipsoidal height ( ). The term is based on the assumption that the geoid varies with topography and may hence possibly lead to some improvements in accuracy of orthometric height determination. DGPS observations were carried out to determine ellipsoid heights. Least squares adjustment was performed to compute the coefficients of the models. Model A achieved standard deviation of σ = 11 cm while Model B achieved σ = 13cm. Though, Model B has a term that included highly accurate ellipsoidal height differences ( ), it has not resulted into any accuracy improvement over the model A. Model A based on 2-D positions is hence the better of the two models. The t-test and hypothesis test at 95% confidence limit, however, showed that the two models did not differ significantly. Model A having lower standard deviation is recommended with GNSS determined ellipsoidal heights to determine orthometric heights within the FCT. This becomes an easy alternative to conventional spirit leveling technique for production of topographical maps, cadastral surveys, and engineering/environmental applications.
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Menegbo, Emmanuel. "Determination of orthometric elevations using gnss-derived height with the egm2008 geoid height model." International Journal of Advanced Geosciences 5, no. 1 (2017): 13. http://dx.doi.org/10.14419/ijag.v5i1.7190.

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The Global navigation satellite systems (GNSS) has imparted positively on civilian positioning & surveying in the horizontal component in Nigeria for the past two decades. The GNSS receivers’ data are longitude, latitude & elevation. However, the vertical distance measurement have not been fully exploited by geodetic and land surveyors. The GNSS derived heights are ellipsoidal elevation. To convert the GNSS elevation to orthometric heights, a geoidal elevation models is needed. The Earth Gravitational Model, 2008 (EGM2008) is a global geoidal models that can be used to obtain GNSS orthometric heights by defining the relationship with the ellipsoid. This work determines GNSS-derived orthometric heights with ellipsoid-geoidal relationship using GPS ellipsoidal heights and EGM2008 geoidal model GIS data. The EGM2008 GIS data was downloaded and interpolated with GPS data to obtain geoidal heights using ArcGIS 10.1. GNSS-derived heights determined with geoid-ellipsoid relationship formula. The result shows minimum elevation of -2.37599m and maximum elevation of 53.8566m.The derived orthometric heights use to create a model in raster format. The orthometric elevation models created useful in all vertical surveying work, construction work and urban planning. The GNSS orthometric heights models need to be compare with spirit levelling and the local geoidal model determined for improve accuracy.
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Eteje, S. O., and V. N. Ugbelase. "Comparative Analysis of the Molodensky and Kotsakis Ellipsoidal Heights Transformation between Geocentric and Non-Geocentric Datums Models." Journal of Geography, Environment and Earth Science International 25, no. 10 (2021): 171–77. https://doi.org/10.9734/JGEESI/2021/v25i1030323.

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The non-availability of ellipsoidal heights of local geodetic Datums has made it necessary for the application of ellipsoidal heights transformation models to the available global ellipsoidal heights to obtain their respective theoretical heights in local Datums. It is required to know the accuracy, as well as reliability of any model of interest before its application. For that reason, this study comparatively analyses the Molodensky and Kotsakis models for the transformation of ellipsoidal heights between geocentric and non-geocentric Datums to determine the reliability of the Kotsakis model. The Global Navigation Satellite System (GNSS) data of the used stations were processed in World Geodetic System 1984 (WGS84) datum to obtain their global geographic coordinates and ellipsoidal heights. The coordinates, ellipsoidal heights and the transformation parameters between WGS84 and Minna Datums were applied to the Molodensky and Kotsakis models to compute the Clarke 1880 theoretical heights of the stations. The Molodensky model was used as a reference to which the Kotsakis model ellipsoidal heights were compared to obtain the Kotsakis model ellipsoidal heights discrepancies, as well as residuals. The residuals were used to compute the Root Mean Square Error (RMSE) of the Kotsakis model. The computed RMSE, as well as reliability of the model is 1.244 m. The study concluded that the low reliability, as well as accuracy of the Kotsakis model might be as a result of the two rotation datum shift parameters in it as they are the main differences between the two models.
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David Mayunga, Selassie. "Determination and Analysis of Height Differences between Orthometric and Ellipsoidal Heights for Engineering Applications." International Journal of Science and Research (IJSR) 12, no. 8 (2023): 1653–61. http://dx.doi.org/10.21275/sr23815133647.

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ETEJE, S. O., O. F. ODUYEBO, and S. A. OLULADE. "Procedure for the Determination of Local Gravimetric-Geometric Geoid Model." International Journal of Advances in Scientific Research and Engineering (ijasre) 4, no. 8 (2018): 206–14. https://doi.org/10.5281/zenodo.2525708.

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As the surface adopted for geodetic computation is a mathematical surface which is different from the physical surface, the geoid adopted as a reference for the vertical coordinate system, the ellipsoidal heights obtained from GPS observation are transformed to practical heights known as orthometric heights. The transformation of the ellipsoidal heights to orthometric heights requires the knowledge of the geoid-ellipsoid separation at the point of observation. Since the geometric method requires the computation of geoid heights of points from GPS observation and geodetic leveling carried out over long distances which are labor intensive and prone to human errors, the accurate geoid heights of the points should be obtained from gravity measurement and a geometric geoid surface fitted to the gravimetric geoid heights. This paper presents detailed procedures for determining local gravimetric-geometric geoid model of an area or a region. The detailed procedures which consist of selection of suitable/evenly distributed points, DGPS and gravity observations of selected points, processing of DGPS and gravity observations, computation of gravimetric geoid heights of the points, fitting of geometric geoid surface to the computed gravimetric geoid heights and computation of accuracy of the geoid model are presented in sequential order.
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Kuhar, Miran, Robert Brglez, and Božo Koler. "Quality determination of mean sea level heights with GNSS levelling on the Ljubljana city area." Geodetski vestnik 65, no. 02 (2021): 219–33. http://dx.doi.org/10.15292/geodetski-vestnik.2021.02.219-233.

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This paper describes the quality determination of heights above mean sea level using RTK GNSS-levelling and new height reference surface SLO_VRP2016/Koper on the city area of Ljubljana. At 57 chosen benchmarks, quasigeoid heights were determined using ellipsoidal heights, determined with RTK GNNS-levelling technique and heights above mean sea level in the new height system SVS2010. The measured quasigeoid heights were compared with values interpolated from the new height reference surface SLO_VRP2016/Koper.
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Badejo, OT, KFA Aleem, and JB Olaleye. "REPLACING ORTHOMETRIC HEIGHTS WITH ELLIPSOIDAL HEIGHTS IN ENGINEERING SURVEYS." Nigerian Journal of Technology 35, no. 4 (2016): 761. http://dx.doi.org/10.4314/njt.v35i4.10.

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Goli, M., and M. Najafi-Alamdari. "Planar, spherical and ellipsoidal approximations of Poisson's integral in near zone." Journal of Geodetic Science 1, no. 1 (2011): 17–24. http://dx.doi.org/10.2478/v10156-010-0003-6.

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Planar, spherical and ellipsoidal approximations of Poisson's integral in near zonePlanar, spherical, and ellipsoidal approximations of Poisson's integral for downward continuation (DWC) of gravity anomalies are discussed in this study. The planar approximation of Poisson integral is assessed versus the spherical and ellipsoidal approximations by examining the outcomes of DWC and finally the geoidal heights. We present the analytical solution of Poisson's kernel in the point-mean discretization model that speed up computation time 500 times faster than spherical Poisson kernel while preserving a good numerical accuracy. The new formulas are very simple and stable even for regions with very low height. It is shown that the maximum differences between spherical and planar DWC as well as planar and ellipsoidal DWC are about 6 mm and 18 mm respectively in the geoidal heights for a rough mountainous area such as Iran.
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Zlinszky, A., G. Timár, R. Weber, et al. "Observation of a local gravity potential isosurface by airborne lidar of Lake Balaton, Hungary." Solid Earth 5, no. 1 (2014): 355–69. http://dx.doi.org/10.5194/se-5-355-2014.

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Abstract. Airborne lidar is a remote sensing method commonly used for mapping surface topography in high resolution. A water surface in hydrostatic equilibrium theoretically represents a gravity potential isosurface. Here we compare lidar-based ellipsoidal water surface height measurements all around the shore of a major lake with a local high-resolution quasi-geoid model. The ellipsoidal heights of the 87 km2 we sampled all around the shore of the 597 km2 lake surface vary by 0.8 m and strong spatial correlation with the quasi-geoid undulation was calculated (R2 = 0.91). After subtraction of the local geoid undulation from the measured ellipsoidal water surface heights, their variation was considerably reduced. Based on a network of water gauge measurements, dynamic water surface heights were also successfully corrected for. This demonstrates that the water surface heights of the lake were truly determined by the local gravity potential. We conclude that both the level of hydrostatic equilibrium of the lake and the accuracy of airborne lidar were sufficient for identifying the spatial variations of gravity potential.
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Mihalache, Raluca Maria, and Andreea Manescu. "Interpolation Grid for Local Area of Iasi City." Present Environment and Sustainable Development 8, no. 1 (2014): 157–64. http://dx.doi.org/10.2478/pesd-2014-0014.

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Abstract Definitive transition to GNSS technology of achieving geodetic networks for cadastre implementation in cities and municipalities, enforce establishing a unique way of linking between current measurements and existing geodetic data, with a sufficient accuracy proper to urban cadastre standards. Regarding city of Iasi, is presented a different method of transformation which consist in an interpolation grid for heights system. The Romanian national height system is „Black Sea-1975” normal heights system. Founded in 1945 by Molodenski, this system uses the quasigeoid as reference surface, being in relation with the ellipsoid through the height anomalies sizes in each point. The unitary transformation between the ETRS- 89 ellipsoidal height system and the normal one, at national level is provided through the „TransdatRo” program developed by NACLR (National Agency for Cadastre and Land Registration).
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Dissertations / Theses on the topic "Ellipsoidal Heights"

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Ugur, Mehmet Ali. "Modeling the Neutral Atmosphere in Continuously Operating GNSS Networks using OPUS-Projects." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357277355.

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Zmitrovičienė, Danutė. "Normalinių ir elipsoidinių aukščių sąsajos analizė (vakarų Lietuvoje)." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050630_114307-69270.

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Magistro baigiamajame darbe „Normalinių ir elipsoidinių aukščių sąsajos analizė (vakarų Lietuvoje) yra analizuojamas normalinių aukščių prognozės modeliai, sudaryti taikant kolokacijos metodą. Tam tikslui yra panaudojami 1-os klasės vertikaliojo tinklo GPS matavimų duomenys – punktų elpisoidiniai aukščiai bei jų koordinatės LKS 94 sistemoje ( vakarų Lietuvos dalyje). Prognozinio normalinio aukščio tikslumui įvertinti buvo panaudojami trys analizės variantai: taikant 5-ių, 6-ių ir 7-ių parametrų variantus. Įvertinama modelio kaita priklausomai nuo parametrų skaičiaus. Analizuojama klaidų įtaka prognozės modelio parametrų bei prognozinių normalinių aukščių tikslumui.<br>The thesis „The analysis of normal and ellipsoidal heights interrelation“ examines the making of the normal heights prognosis models, employing the Kolokation method. In that case, are used 1rst class vertical Lithuanian levelling network data measurements by GPS - point with elipsoidal heigts and their coordinates in the LKS 94 system (Western Lithuania). It was used three analysis variants for the evaluation of the accuracy of the prognostic normal heights: 5th, 6th, 7th parameters variants.This is performed by changing the sequence of the polynoms and elements of matrix of weights at elipsoidic and normal heights. The analysis of the influence of the prognostic model errors for the accuracy of the parametrs and prognostic normal heights.
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Tseng, Jung-Ho, and 鄭榮和. "Orthometric Height Determination by GPS Ellipsoidal Heights and a prior Information of Local Geoid." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/89196148514682628033.

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碩士<br>國立成功大學<br>測量工程學系<br>89<br>The datum inconsistency must be taken into consideration for the orthometric height determination by integration of GPS heights,spirit heights and the geoidal undulation ,because those heights refer to different reference surfaces. In the study, a height datum transformation model has been developed,and the least squares collocation has been used for solving the systematic errors caused by a priori undulation model and height networks. It is shown that the transformation model developed in the study can improve the absolute accuracy of orthometric heights compared with models that do not consider the datum inconsistency problem and the systematic errors. The absolute accuracy of transformed orthometric heights is about 2-3 cm both for the local and for linear leveling height transformation with a global undulation model EGM96 or a local undulation model. But the relative accuracy of all transformation models tested in the study is similar.
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Books on the topic "Ellipsoidal Heights"

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D, D'Onofrio Joseph, Frakes Stephen J, and National Geodetic Survey (U.S.), eds. Guidelines for establishing GPS-derived ellipsoid heights (standards, 2 cm and 5 cm), version 4.3. U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, National Ocean Service, National Geodetic Survey, 1997.

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Book chapters on the topic "Ellipsoidal Heights"

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Tavasci, Luca, Enrica Vecchi, and Stefano Gandolfi. "Definition of the Local Geoid Undulation Using Non-contemporary GNSS-Levelling Data on Subsidence Area: Application on the Adriatic Coastline." In Communications in Computer and Information Science. Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-94426-1_19.

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AbstractThe knowledge of the so-called geoid undulation, which represents the height of the geoid above a reference ellipsoid, is a fundamental step to link ellipsoidal heights measured using satellite systems and orthometric heights. Several geoid models are available at the time both at the national or global scale, which can be used for the purpose. Another way to define the geoid undulation is to perform joint measures with GNSS and spirit levelling over common benchmarks. This requires onerous measurements that is seldom possible to perform due to their cost. In this work, we evaluated the possibility to define a local model of the geoid undulation using already available spirit levelling orthometric heights and GNSS ellipsoidal heights measured about 13 years later. The test area is the Emilia-Romagna Adriatic coastline, an area of great interest both from the environmental and economic point of view, which is also undergoing consistent subsidence phenomena.Test results show that the available measurements allow defining a geoid undulation that is coherent with the shape defined by the gravimetric models and also allows to transform ellipsoidal heights into orthometric ones more consistent with the height reference available on the surveyed area. A 7 cm overall bias with respect to the ITALGEO05 was found, whereas ITG2009 and EGM2008 have higher differences. The use of subsidence models to align over time the coordinates used to define the geoid undulation has proven to be a fundamental step. The analysis on the a-priori uncertainty in the geoid height definition shown that the combined use of much more precise GNSS coordinates and contemporary spirit levelling campaign is necessary to significantly improve the resulting geoid height.
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Brunini, C., J. Moirano, H. Drewes, and K. Kaniuth. "Improvements in the Ellipsoidal Heights of the Argentine Reference Frame." In International Association of Geodesy Symposia. Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-04683-8_4.

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Grafarend, E., and F. I. Okeke. "3D Linear Similarity Coordinate Transformation between a Global Geodetic System and a Local Geodetic System without Local Ellipsoidal Heights." In International Association of Geodesy Symposia. Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79824-5_5.

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Sneeuw, Nico, Muriel Bergé-Nguyen, and Jean-François Crétaux. "Physical Heights of Inland Lakes." In International Association of Geodesy Symposia. Springer Berlin Heidelberg, 2023. http://dx.doi.org/10.1007/1345_2023_192.

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AbstractInland satellite altimetry has gained traction over the past decade and is now routinely used to monitor the water levels of rivers, lakes and reservoirs. The accuracy of such inland water height measurements, at least from radar altimetry is still relatively poor from a geodetic viewpoint, namely in the range of several decimeter. Accuracies from spaceborne laser altimetry, in particular from the ICESat-2 mission, are at cm-level, however, and further progress in the radar altimetry domain is expected from swath-based altimetry by the SWOT mission, (to be) launched December 2022. With accuracies down to cm-level one needs to reconsider the height system definition of inland lake surfaces as obtained from satellite altimetry. Conventionally one subtracts a global geoid model from the altimetry-derived ellipsoidal height to obtain an orthometric height. Without wind stress, seiches and other time-variable height disturbances the lake water surfaces will conform to equipotential surfaces in the Earth’s gravity field. Thus lake surfaces are surfaces of constant dynamic height, from which follows that a lake surface cannot be a surface of constant orthometric or normal height. Because equipotential surfaces are inherently non-parallel, two points at a lake surface can and will have different orthometric height. Although being well-understood in physical geodesy, we will here model this effect and quantify it for various case studies. We demonstrate that the effects can be as large as a few dm for large lakes at high altitudes, which is an order of magnitude that is relevant in terms of satellite altimetry error levels.
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Sohor, Andrii. "A PRIORI RESEARCH RELATED TO THE CALCULATION OF THE REGIONAL ELLIPSOID FOR UKRAINE AND ITS EFFECTIVENESS." In Theoretical and practical aspects of the development of modern scientific research. Publishing House “Baltija Publishing”, 2022. http://dx.doi.org/10.30525/978-9934-26-195-4-13.

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Despite the high accuracy of global geodetic reference systems and their widespread use in GPS measurements, regional (local) geodetic systems are becoming more widely used. For example, the World Geodetic System 1984 (WGS84) has 83 such local systems. The emergence of the latter is caused by the emergence of new problems of physical geodesy. These are the so-called regional problems, which make it possible to study in more detail both the geometric and gravimetric (physical) properties of the studied region (territory). For example, the tasks of constructing a high-precision regional geoid (quasi-geoid), regional ellipsoid, determining the regional normal formula of gravity, and others are becoming increasingly important. That is why at present both national and regional reference ellipsoids are accepted for processing geodetic data on a regional scale (for example, for a specific country), and for global research – a general terrestrial reference ellipsoid GRS80 or, when processing GPS data – a general terrestrial reference ellipsoid WGS84.In principle, any reference ellipsoid that represents a generalized figure of the Earth with appropriate accuracy can be used to process geodetic information. The deviations of the geoid from such an ellipsoid can determine the corrections that must be made in the results of geodetic measurements to bring the latter to the surface of this ellipsoid. However, with large deviations of the geoid from the reference ellipsoid, there are large corresponding reductions of geodetic measurements, which are burdened with significant errors due to the linearization of the main problem of geodesy and, consequently, the problem of bringing geodetic measurements to the ellipsoid. Therefore, from a practical point of view, to reduce the impact of these linearization errors and obtain methodologically optimal results of geodetic data processing, it is expedient and even necessary to use a reference ellipsoid that best describes the generalized geoid surface in the region of specific geodetic works.Given the above, the question arose about the national reference coordinate system, as such a system has some advantages over the national system in the process of practical processing of mass geodetic measurements, especially linear. In this regard, the issues of building a national reference system, namely, the definition of a regional ellipsoid, are very important and relevant. Therefore, the scope of our research is the construction of a national reference system based on data on the regional gravitational field of Ukraine. The methodology of such research is that the task of determining the regional ellipsoid is practically reduced to finding some corrections to the known, accepted by us, the general terrestrial ellipsoid GRS80. The regional ellipsoid for the territory of Ukraine should be the one that would best represent the geoid (quasi-geoid) of the region. That is, the heights of the geoid relative to the regional ellipsoid within the territory of Ukraine should be as small as possible. These questions are reflected in this monograph, the purpose of which is to investigate a priori calculations to determine the parameters of the internal orientation of the regional ellipsoid according to its gravitational field in Ukraine. Thus, based on the results of the above a priori studies, the following can be noted. Determining all five parameters of a regional ellipsoid leads to a strong functional dependence of the parameters. This dependence (correlation) is quite well demonstrated on the values of root mean square errors, which are proportional to the obtained parameters and even exceed the latter. Taking into account these remarks, we can conclude that the joint calculation of all five parameters by the method of least squares on the territory of Ukraine does not give us the expected good results. This is well seen from a priori calculations based on the heights of the geoid, presented in the form of a spheroidal trapezoid, which describes the territory of Ukraine. In contrast to this solution, studies to determine only the parameters of the internal orientation of the ellipsoid at a given major half-axis and compression of this ellipsoid, make it possible to choose a terrestrial regional ellipsoid that would best represent a geoid (quasi-geoid) built in Ukraine.
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Foroughi, Ismael, Mehdi Goli, Stephen Ferguson, and Spiros Pagiatakis. "Optimizing Airborne Flight Line Spacing for Geoid Determination with Full Gravity Vectors." In International Association of Geodesy Symposia. Springer Berlin Heidelberg, 2024. http://dx.doi.org/10.1007/1345_2024_253.

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AbstractThe horizontal components of the airborne gravity vector are equivalent to the deflection of the vertical at the flight level and contain signals of the slope of Earth’s gravity field. We test the contribution of such components in finding the optimum flight line spacing for geoid modelling. We use the one-step integration method and create a system of linear equations containing the three components of the airborne gravity vector as observations and solve the geodetic boundary value problem on the reference ellipsoid as an overdetermined weighted least-squares problem. We test our methodology in the Colorado region in the USA given that it is one of the most challenging areas for geoid modelling. We show that by incorporating the horizontal components at the flight level, one can increase the flight line spacing by almost 40%, thereby significantly reducing the cost of airborne surveys while maintaining the same accuracy in the estimated geoid heights as when the scalar value of gravity is used.
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Dávila-Gonzalez, Juan Pablo, and José Dalma-Weiszhausz. "Postoperative Ocular Perfusional Findings in Successfully Reattached Severe Proliferative Vitreoretinopathy, An OCT-A Evaluation." In Optical Coherence Tomography Angiography for Choroidal and Vitreoretinal Disorders – Part 2. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815196658123010007.

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Rhegmatogenous retinal detachment (RRD) is the separation of the neurosensory retina from the underlying retinal pigment epithelium (RPE) and is one of the leading causes of severe vision loss when it involves the macula or proliferative vitreoretinopathy (PVR) in different stages. Optical coherence tomography (OCT) and Optical coherence tomography - angiography (OCT-A) have opened a new scenario in the investigation of macular microstructural abnormalities in RRD. Findings in the preoperative retinal detachment structural B-scans in OCT such as ellipsoid zone (EZ)/external limiting membrane (ELM) integrity, cavities along the inner nuclear layer (INL) or outer nuclear layer (ONL), retinal height of detachment at the fovea, presence of retinal folds and subfoveal choroidal thickness may predict the functional and structural outcomes. Structural and en-face analysis with OCT-A in RRD with PVR has demonstrated an enlarged foveal avascular zone, and changes in the flow at the superficial, intermediate and deep capillary plexus during 6 months postoperative follow up. High resolution and deep enhancing imaging OCT-A technology will provide an important role regarding the choriocapillaris and choroid and their potential correlation with visual acuity recovery. OCT and OCT-A will provide preoperative prognostic biomarkers and adequate vascular retinochoroidal layers may influence a postoperative outcome.
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Conference papers on the topic "Ellipsoidal Heights"

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Núñez Andrés, María Amparo, and Felipe Buill Pozuelo. "Necesidad del geoide en el posicionamiento con GPS." In International Conference Virtual City and Territory. Centre de Política de Sòl i Valoracions, 2005. http://dx.doi.org/10.5821/ctv.7401.

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The common use of global positioning systems, and specially GPS, in work like survey,&#x0D; cartography, photogrammmetry, LIDAR... make it necessary have a gemid model to&#x0D; transform ellipsoidal to orthometric heights used in engineering. Because of the lack of&#x0D; parallelism between both reference systems not to have these models can produce important&#x0D; errors since the variation can take values of 10cm/Km or more in some areas, for&#x0D; example in the SW of Spain. If we do not consider this difference in the elaboration of&#x0D; DTM used to design substructure can happen that in gravity canalization the water does&#x0D; not arrive at the wanted point
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Puškorius, Vytautas, Eimuntas Paršeliūnas, Petras Petroškevičius, and Romuald Obuchovski. "An Analysis of Choosing Gravity Anomalies for Solving Problems in Geodesy, Geophysics and Environmental Engineering." In 11th International Conference “Environmental Engineering”. VGTU Technika, 2020. http://dx.doi.org/10.3846/enviro.2020.684.

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Gravity anomalies provide valuable information about the Earth‘s gravity field. They are used for solving various geophysical and geodetic tasks, mineral and oil exploration, geoid and quasi-geoid determination, geodynamic processes of Earth, determination of the orbits of various objects, moving in space around the Earth etc. The increasing accuracy of solving the above mentioned problems poses new requirements for the accuracy of the gravity anomalies. Increasing the accuracy of gravity anomalies can be achieved by gaining the accuracy of the gravimetric and geodetic measurements, and by improving the methodology of the anomalies detection. The modern gravimetric devices allow to measure the gravity with an accuracy of several microgals. Space geodetic systems allow to define the geodetic coordinates and ellipsoidal heights of gravimetric points within a centimeter accuracy. This opens up the new opportunities to calculate in practice both hybrid and pure gravity anomalies and to improve their accuracy. In this context, it is important to analyse the possibilities of detecting various gravity anomalies and to improve the methodology for detecting gravity anomalies. Also it is important the correct selection of the gravity anomalies for different geodetic, geophysical and environmental engineering tasks. The modern gravity field data of the territory of Lithuania are used for the research.
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Buchholz, James H. J., Seyed Mohammad Hajimirzaie, and Craig J. Wojcik. "Flow Structure in the Wake of a Wall-Mounted Bluff Body." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30928.

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This paper discusses an experimental study of the flow field around three different wall-mounted obstacles in a boundary layer within a relatively shallow flow (d/H ≈ 4, where d is the flow depth and H is the obstacle height). The first two obstacles consist of a semi-ellipsoidal body with the major axis of the base ellipse oriented in the streamwise and the transverse direction. The third obstacle is a low-aspect-ratio cylinder, bearing greater similarity to geometries investigated in other studies. Reynolds numbers of 5500 and 17800, based on obstacle height, were investigated. Digital particle image velocimetry was used to characterize the flow field in each case. At ReH = 17800, isocontours of streamwise vorticity reveal the presence of a tip vortex pair and a base vortex pair for each geometry; however, the ratio of the relative strengths of the tip and base vortices varies considerably, with the streamwise-oriented ellipsoid having the largest ratio of tip/base vortex circulation and the transverse ellipsoid having the smallest ratio. The presence of a base vortex for such low-aspect-ratio obstacles is unexpected, and therefore we hypothesize that its existence is related to the small d/H. It is anticipated that variation of geometry and d/H will help to elucidate the role of the base vortex in the three-dimensional vortex structure of the wake.
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Alshareef, Sultan, Todd Harman, and Tim Ameel. "Thermal Fluid Assessment of Bluff Versus Streamlined Bodies With a Slot for Aligned Flow." In ASME 2022 Heat Transfer Summer Conference collocated with the ASME 2022 16th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/ht2022-80024.

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Abstract Heat transfer and flow characteristics for a two-dimensional ellipse of different aspect ratios with single slot aligned with the principal flow direction is investigated numerically. In this study we quantify the change in drag force and heat transfer rate due to the slot. The ellipsoid aspect ratios are 1.0 (circle), 0.75, and 0.5 and the normalized slot height S/a, where S is the slot height and a is the minor-axis length of the ellipsoid, is 0.2. For each aspect ratio, simulations are conducted for both the slotted and solid ellipsoids. Two-dimensional incompressible airflow for Reynolds numbers Rea (based on minor-axis length a) between 100 and 1000 is modeled assuming an isothermal ellipsoid. A maximum drag force reduction of ∼11%, ∼25%, and ∼40% is found for aspect ratios of 0.5, 0.75, and 1.0, respectively, at Rea = 1000. At the same Rea, a maximum heat rate increase of ∼74%, ∼73%, and ∼69% is found for aspect ratios of 0.5, 0.75, and 1.0, respectively. The change in the performance index, defined as the ratio of the heat rate to the drag force, increases up to maximum of ∼1.96, ∼2.33, and ∼2.83 for aspect ratios of 0.5, 0.75, and 1.0, respectively, at Rea = 1000. The improvements are the result of the increased heat transfer area and the reduction in the total drag force, due to the flow interaction with the wake near the exit of the slot. An entropy analysis shows that an ellipsoid, aspect ratio of 1.0, has the best overall thermodynamic performance for 400 ≤ Rea ≤ 1000, whereas the ellipsoid of aspect ratio of 0.5 has the least entropy generation for 100 ≤ Rea ≤ 400. Finally, the ellipsoid with an aspect ratio of 1.0 benefits the most through the addition of the slot, inferring that this feature is most suited to bluff bodies.
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Kumar, Pavan, Satwik Priyadarshi, J. J. Roy, M. K. Samal, P. K. Jain, and Puneet Tandon. "Effect of Tool Shape on Surface Finish of Components Formed Through Incremental Sheet Forming Process." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53282.

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This work explores the effect of tool geometry on surface finish in incremental sheet forming (ISF) process. In the present work, two different tool geometries i.e. hemispherical shaped tool and ellipsoidal shaped tool are considered. Area at tool-sheet contact and scallop height were calculated for both the tool geometries. To assess the effect of tool geometry on the surface finish of the formed components, both analytical and experimental approaches have been used. A test geometry having the shape of frustum of pyramid was considered for the proposed investigation and four surface roughness parameters i.e. arithmetic mean surface roughness (Ra), root mean square surface roughness (Rq), maximum peak-to-valley height (Rt) and average peak-to-valley height (Rz) have been selected as response parameters. Based on the analytical model and experimental investigations, both qualitative and quantitative comparisons had been made among the effects of hemispherical and ellipsoidal tool geometries on surface finish. The investigation deduces that better surface finish of the formed component can be achieved by using ellipsoidal shaped tool rather than the hemispherical shaped tool.
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6

Shah, Pankajkumar K., Mark Belloni, and Robert M. Wilson. "Tentative Thickness for Torispherical and Ellipsoidal ASME Section III Class 1 Heads." In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84934.

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Class 1 nuclear vessel heads with ellipsoidal or torispherical geometries offer several advantages over spherical heads. They shorten the overall height of the vessel, reduce internal volume, lower the vessel center of gravity, and are more economical. At present Section III only offers tentative thickness formulas for spherical heads in NB-3324 [1]. This paper proposes the addition of tentative thickness formulas for Class 1 torispherical and ellipsoidal heads. A large family of finite element analyses over a practical range of vessel geometries and pressures is used to establish the new thickness equations.
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Liu, Peng, Tao Zhou, Haolei Zhang, and Xiaofang Liu. "Research on Heat Transfer Calculation of Ellipsoidal Melt Pool." In 2024 31st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/icone31-134536.

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Abstract The in-vessel melt retention (IVR) technology, as one of the typical technologies to cope with severe accidents in third-generation nuclear power, has been widely used in pressurized water reactor (PWR) nuclear power plants. Based on the computational study of melt pool heat transfer in VVER-1000 under severe accidents, a steady-state heat transfer model of melt retention inside the elliptical lower head pressure vessel was established, and the wall heat flux at each place of the ellipsoidal lower head wall, the thickness of the oxide crust formed by the liquid-phase oxidic layer being cooled and solidified, the residual wall thickness of the pressure vessel, and the failure of the pressure vessel were computed and analyzed. The calculation results show that: the heat flux at the bottom of ellipsoidal pressure vessel lower head is the smallest, the heat flow distribution on the wall surface from the ellipsoidal part to the cylindrical part is discontinuous, and obvious heat focusing effect is observed in the metal layer; the thickness of oxidic crust decreases with the increase of axial height of ellipsoidal melt pool, and the higher the volumetric heat release rate of oxidic pool is, the smaller the thickness of oxidic crust is; the wall of the pressure vessel starts to melt at a certain place of the lower head, and the thickness of wall thins with the increase of heat flux. The wall thickness decreases with the increase of heat flux, and the ablation of the pressure vessel wall increases to the maximum value due to the drastic increase of heat flux in the metal layer area, and the thinner the metal layer is, the smaller the wall thickness of the pressure vessel in contact with the metal layer is, and the greater the probability of failure of the pressure vessel is; therefore, the wall surface of the pressure vessel in contact with the metal layer is the most dangerous position in the case of a serious accident.
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Pelletier, Etienne, C. Beguin, and S. Etienne. "Simple Model for Bubble-Wall Interaction." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28458.

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We have developed a model for an ellipsoidal bubble colliding with a rigid horizontal wall based on potential flow theory. The model is then compared with experiments of air bubbles surrounded by water impacting a wall. 70 impacts were observed with bubble radius between 0.3 and 2 mm and different trajectory types (helicoidal, zig-zag). Deformation and height of the first impact are the main comparison points. The proposed model is in good agreement with the height of the rebound but tends to overestimate the maximal compression for both types of trajectories. We also propose a new relation for the viscous drag coefficient correction induced by the wall confinement as well as the definition of potential pressure forces acting on bubbles close to a wall.
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9

Cerantola, D. J., and A. M. Birk. "The Influence of Tabs on Different Area Ratio Short Annular Diffusers." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25569.

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Square tabs were placed on the base of an ellipsoidal centre body in annular diffusers with length to inlet height of 12. Tests were completed with an inlet Reynolds number of 1 × 105, swirl number of 0.71, and inlet flow blockage of 0.02–0.04. Four outer walls were manufactured with area ratios of 1.61, 1.91, 2.73, and 6.18. The tabs with a projected height equivalent to the boundary layer thickness were effective at reducing the outlet distortion but at a pressure penalty for the three smaller diffusers. The largest diffuser improved back pressure coefficient 4.6% with four tabs providing a blockage of 4.7% over its bare diffuser but was 42% lower than that obtained by the AR = 2.73 diffuser with no tabs.
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Durand, Stéphane, Michael Lösler, Mark Jones, Paul-Henri Cattin, Sébastien Guillaume, and Laurent Morel. "Quantification of the dependence of the results on several network adjustment applications." In 5th Joint International Symposium on Deformation Monitoring. Editorial de la Universitat Politècnica de València, 2022. http://dx.doi.org/10.4995/jisdm2022.2022.13671.

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The dependency of the results from a network adjustment on the application used is investigated. For that purpose, the results obtained by each tested application on several sets of simulated measurements are compared. In each simulation, only one parameter varies. We first present our comparison methodology and the method that was used to add Gaussian-like errors to theoretical measurements. We then apply it to study the impact of the side length of the network and of the ellipsoidal height difference among points in the network for several network adjustment applications: Columbus, CoMeT, Geolab, JAG3D, LGC, Move3, Star*Net and Trinet+.
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