299 research outputs found
Ellipsoidal topographic potential: New solutions for spectral forward gravity modeling of topography with respect to a reference ellipsoid
No full textForward gravity modeling in the spectral domain traditionally relies on spherical approximation. However, this level of approximation is insufficient for some present day high-accuracy applications. Here we present two solutions that avoid the traditional spherical approximation in spectral forward gravity modeling. The first solution (the extended integration method) applies integration over masses from a reference sphere to the topography and applies a correction for the masses between ellipsoid and sphere. The second solution (the harmonic combination method) computes topographic potential coefficients from a combination of surface spherical harmonic coefficients of topographic heights above the ellipsoid, based on a relation among spherical harmonic functions introduced by Claessens (2005). Using a degree 2160 spherical harmonic model of the topographic masses, both methods are applied to derive the Earth’s ellipsoidal topographic potential in spherical harmonics. The harmonic combination method converges fastest and—akin to the EGM2008 geopotential model—generates additional spherical harmonic coefficients in spectral band 2161 to 2190 which are found crucial for accurate evaluation of the ellipsoidal topographic potential at high degrees. Therefore, we recommend use of the harmonic combination method to model ellipticity in spectral-domain forward modeling. The method yields ellipsoidal topographic potential coefficients which are “compatible” with global Earth geopotential models constructed in ellipsoidal approximation, such as EGM2008. It shows that the spherical approximation significantly underestimates degree correlation coefficients among geopotential and topographic potential. The topographic potential model is, for example, of immediate value for the calculation of Bouguer gravity anomalies in fully ellipsoidal approximation
Interculturality - narrative forms in Sten Nadolny's novels
No full textDie Dissertation zum Thema -»Interkulturalität - Erzählformen im Werk von Sten Nadolny-« behandelt ausgewählte Romanwerke von Sten Nadolny, nämlich "Die Entdeckung der Langsamkeit" (1983) und "Selim oder Die Gabe der Rede" (1990). In ihr werden die Ambivalenz des Verhältnisses von Eigenem und Fremdem und die dazu in den Texten praktizierten Modelle des Austauschs zwischen diesen beiden Instanzen untersucht. Die in den Romanen angesprochenen Problemfelder der 'Langsamkeit' und der 'Rede' erscheinen als zwei Merkmale randständiger Identität, die in Opposition und wechselseitigem Dialog mit den herrschenden Wahrnehmungen und Verständnissen der Umgebung stehen. Die Thematik der Interkulturalität als Wechselwirkung von Fremdem und Eigenem und ihre erzähltechnische Verwirklichung in den Romanen umfassen Aspekte des Inhalts und der Form. Ihre Betrachtung in der vorliegenden Arbeit ist durch die eigene fremdkulturelle Sicht der untersuchenden Instanz geprägt. Damit aber wird eine Infragestellung herkömmlicher Methoden der Analyse möglich. Das Ziel ist, eine neue (fremdkulturelle) Perspektive bei der Behandlung von interkulturell bezogenen Werken einzubeziehen. Dazu dient insbesondere die Betrachtung der Wechselwirkung zwischen alternativen erzähltechnischen Ausdrucksmöglichkeiten und alternierenden Erzählinhalten in Nadolnys erzählerischem Konzept. Die Auseinandersetzung der Literaturkritik mit dem Thema des Fremden und Eigenen wird durch das Verständnis der Verfasserin aus fremder Sicht kritisch kommentiert. Die vorliegende Arbeit umfasst fünf Kapitel. Auf das Konzept des Erzählers Sten Nadolny, sein Verständnis des Erzählens und seine Erzähltechnik wird auch im Rahmen der Diskussion um die ›Postmoderne‹ eingegangen. Hierbei soll besonders auf sein Arbeitsverfahren aufmerksam gemacht werden, das sich den ästhetischen Möglichkeiten des "fremden Blicks" widmet. Kapitel II und III gehen auf die Konstruktion der Lebensgeschichten und anschließend auf den Wechsel der Erzählformen ein. In Kapitel IV legen Schlussfolgerungen aus dieser Auseinandersetzung mit Werk und Erzähler Position und Rolle Sten Nadolnys in der deutschen Gegenwartsliteratur fest. Die Arbeit endet mit einem Kapitel zur Literatur über Sten Nadolny und sein Werk, Erzählen, Interkulturalität und Postmoderne.This dissertation "Interculturality - narrative forms in Sten Nadolny- novels" treats selected novel works of Sten Nadolny, i.e. "The Discovery of Slowness" (1983) and "Selim or The Gift of Speech" (1990). The ambivalence of the relationship between the Self and the Other as well as the types of exchange between these two instances is practiced in the texts and examined. The problematic forms of 'slowness' and 'speech' addressed in both novels appear to reinforce a sense of "exiled" identity, which stands as two characteristics in opposition and mutual dialogue with the dominant perceptions and understandings of the environment. Their narrative implementation in the novels, in the contents and in their formal structure address the issue of Interculturality as a reciprocal relationship between the self and the other. The characters" points of view in the available works are changed by the presence of foreigners" cultural viewpoints. Thus the questioning of conventional methods of the analysis becomes possible. The goal of this dissertation is to include within this perspective a treatment of intercultural references. In addition the dissertation discusses in particular the view of reciprocity between alternative structural possibilities and alternative narrative possibilities in Nadolny- work. A discussion of the literary critical history on the history of the Other and the Self is augmented by the author- own perspective on foreignness. The argument is divided into five chapters. The first chapter explores the concept of the storyteller Sten Nadolny within the context of Postmodernism criticism. Here particular attention is paid to his narrative structure and the aesthetic possibilities of the "foreign" view. Chapters II and III deal with the construction of life stories and the subsequent transformation of the narrative forms. In the concluding chapters the storyteller- positionality and role of Sten Nadolnys in contemporary German literature. The work ends with a chapter dedicated to the literature about Sten Nadolny, his work, narration, interculturality and postmodernism
Use of topography in the context of the GOCE satellite mission - some examples
No full textThe uppermost masses of the lithosphere - notably the land topography, bathymetry and ice - make a significant contribution to the gravity signal captured by ESA’s GOCE gravity mission [1,2]. This circumstance is used 1) to evaluate ESA GOCE gravity field models of all generations, 2) to evaluate various topographic data sets and 3) to compute a global Bouguer gravity anomaly map. All of the above is facilitated through forward modelling of the ellipsoidal topographic potential (ETP) applying the Harmonic Combination Method [3]. Curtin University’s new rock-equivalent topography (RET) model, taken from the Earth2014 suite of topographic data [4], serves as topographic input model for the gravity forward modelling. ESA GOCE models show steady improvement over time and prove to be sensitive for topographic gravity signals at scales of ~100 km and finer. Using the release-5 GOCE models as a reference, Curtin University’s RET models are found to improve over time too. Finally, we demonstrate that the spectral representation of the ETP allows straightforward
computation of global Bouguer anomaly maps
Topographic evaluation of fifth-generation GOCE gravity field models – globally and regionally
No full textESA (European Space Agency) has released a series of new-generation Earth gravity field models computed from gradiometry and GPS observations carried out aboard the GOCE (Gravity field and Ocean Circulation Explorer) satellite. In order to assess the quality of the new GOCE gravity fields, the sensitivity of satellite gravimetry to the gravitational attraction of the topographic masses can be exploited. This study uses topographic mass models to evaluate five generations of GOCE gravity models, both globally and regionally. As model representing Earth’s topography, ice-sheet and waterbody masses we use the new RET2014 rock-equivalent topography model by Curtin University (Perth). The gravitational potential of the RET2014 model is computed in spherical harmonics and in ellipsoidal approximation (ellipsoidal topographic potential, cf. Claessens and Hirt 2013, JGR Solid Earth, 118, 5991). We compare gravity from GOCE and from the RET2014 topography, whereby similar signal characteristics are taken as a sign of quality for the GOCE gravity fields.Our topographic evaluation shows a steadily improved agreement of the five model generations with topographyimplied gravity, and increase in GOCE model resolution. For the fifth-generation GOCE gravity fields, full resolution is indicated to harmonic degree ~220 (90 km scales), and partially resolved gravity features are found to degree ~270 (time-wise approach, TIM) and degree ~290-300 (direct approach, DIR), As such, the 5th-generation GOCE models capture parts of the gravity field signal down to ~70 km spatial scales. This is a very significant improvement in satellite-only static gravity field knowledge compared to the pre-GOCE-era. Our comparisons show that models from the DIR approach improved relative to those from the TIM approach from the 2nd to the 5th generation, with DIR offering the best short-scale performance (from degree 240 and beyond). Considering the unprecedented gravity field resolution achieved, the GOCE gravity field mission performed beyond the expectations. The GOCE gravity fields will serve as a de-facto-standard in a range of applications encompassing geodesy, geophysics and oceanography
STEN NADOLNY i sztuka opowiadania życia
No full textIm Autobiographiediskurs spielen Romane bisher keine nennenswerte Rolle als theoretische Impulsgeber. Der vorliegende Beitrag zeigt, dass STEN NADOLNYS Selim oder Die Gabe der Rede eine autofiktionale Situation im inneren der diegetischen Welt erzeugt und sich damit für die Reflexion autobiographietheoretischer Problemkontexte eignet. Mit Rekurs auf Kristevas Überlegungen zur Selbst-Fremdheit werden die ‚autofiktionalen‘ Schreibakte vorgeführt, die das Individuum auch vom Fremden her erschreiben. Als dezentrierte Selbstlebensbeschreibung überschreitet NADOLNYS Roman damit gängige Formen der Autofiktion.Discourse concerning autobiography does not usually include novels as material for theoretical study. This article demonstrates how STEN NADOLNY’S novel Selim oder Die Gabe der Rede creates an autofictional situation within a diegetic world; therefore it may be a subject of reflection on theoretical problems associated with autobiography. In the context of Julia Kristeva’s deliberations on self-alienation, the Author discusses ‘autofictional’ acts of writing that describe the self through the ‘other’. As decentered life-writing, NADOLNY’S novel transcends common forms of autofiction.W rozważaniach nad autobiografią gatunek powieściowy odgrywał do niedawna mało istotną rolę jako przedmiot badań. Artykuł pokazuje, że powieść STENA NADOLNEGO Selim oder Die Gabe der Rede tworzy w świecie przedstawionym sytuację autofikcjonalną. Tym samym można ten utwór poddać teoretycznej refleksji w odniesieniu do autobiografii. W kontekście rozważań Julii Kristevy na temat obcości podmiotu wobec samego siebie, przedstawione zostają autofikcjonalne strategie pisarskie, które wywodzą autobiografię od ‚obcego’. Powieść NADOLNEGO – można ją nazwać ‚zdezorientowanym’ opisem samego siebie – przekracza wobec tego tradycyjne formy autofikcji
Vem är »Maja Lundgren« i Maja Lundgrens Myggor och tigrar? Fakta och fiktion som ontologi, framställningssätt eller retorisk kommunikationsakt
No full textSten Wistrand is associate professor in comparative
literature at Örebro University.Maja Lundgren’s outspoken description in Myggor och tigrar
(2007) of the male dominated cultural life of Sweden raised an
animated debate in media. Well known authors and journalists
felt themselves scandalized and accused Lundgren of being
paranoid. Others claimed that the narrator and character
»Maja Lundgren« was not to be confused with Maja Lundgren
the author, because the book was fictional and not factual. In
this article I discuss Myggor och tigrar out from different
fiction theories and conclude that it seems most rewarding to
approach the problem of fictionality as a question of rhetorical
communication rather than ontology or stylistic devices. I also
maintain that Lundgren’s book would implode if read as fiction,
since the rhetorical strategy implies the identity of the
author and the character
The Phantom Walking the Text: The Death of the Author Reconsidered.
No full textThe author was killed by Roland Barthes in 1968 in the essay "The Death of the Author". This was an act of euthanasia, forming part of a larger poststructuralist project of putting down obdurate rhetorical practices in literature, where the endorsement of myths like authenticity, the representational value of language, the idea of the final analysis, according to Barthes, had unreasonably governed the ways in which literature was written, read and understood. The author figured as a mark of power, as the authority of a closed sign-system, dictating, or centralising, the ways in which a text must be read. With the author over and done with and the general rhetorical ploys of narration demasked, stripping language to represent nothing but itself, the stage was set for a new understanding (and practice) of literature as a particularly decentred and liberating zone that would seize on any form of power discourse - history, anthropology, politics, religion, etc - still abusing the powers of deception in language in the interest of the speaker.
Solutions to ellipsoidal boundary value problems for gravity field modelling
No full textThe determination of the figure of the Earth and its gravity field has long relied on methodologies that approximate the Earth by a sphere, but this level of accuracy is no longer adequate for many applications, due to the advent of new and advanced measurement techniques. New, practical and highly accurate methodologies for gravity field modelling that describe the Earth as an oblate ellipsoid of revolution are therefore required. The foundation for these methodologies is formed by solutions to ellipsoidal geodetic boundary-value problems. In this thesis, new solutions to the ellipsoidal Dirichlet, Neumann and second-order boundary-value problems, as well as the fixed- and free-geodetic boundary-value problems, are derived. These solutions do not rely on any spherical approximation, but are nevertheless completely based on a simple spherical harmonic expansion of the function that is to be determined. They rely on new relations among spherical harmonic base functions. In the new solutions, solid spherical harmonic coefficients of the desired function are expressed as a weighted summation over surface spherical harmonic coefficients of the data on the ellipsoidal boundary, or alternatively as a weighted summation over coefficients that are computed under the approximation that the boundary is a sphere.Specific applications of the new solutions are the computation of geopotential coefficients from terrestrial gravimetric data and local or regional gravimetric geoid determination. Numerical closed-loop simulations have shown that the accuracy of geopotential coefficients obtained with the new methods is significantly higher than the accuracy of existing methods that use the spherical harmonic framework. The ellipsoidal corrections to a Stokesian geoid determination computed from the new solutions show strong agreement with existing solutions. In addition, the importance of the choice of the reference sphere radius in Stokes's formula and its effect on the magnitude and spectral sensitivity of the ellipsoidal corrections are pointed out
Efficient transformation from Cartesian to geodetic coordinates
No full text© 2019 Elsevier Ltd The derivation of algorithms for the computation of geodetic coordinates from 3D Cartesian coordinates has been a very active field of research among geodesists for more than forty years. Many authors have sought the most efficient method, i.e. the method that provides the fastest computational speed, which nevertheless yields sufficient accuracy for practical applications. The problem is a special case of a more general mathematical problem that has also been studied by researchers in other fields. This paper investigates the applicability of methods by Sampson (1982, Computer graphics and image processing, 18: 97–108) and Uteshev and Goncharova (2018, Journal of Computational and Applied Mathematics, 328: 232–251) to the computation of geodetic coordinates. Both methods have been modified to make them more suitable for this particular problem. The methods are compared to several commonly used geodetic methods in terms of accuracy and computational efficiency. It is found that a simple modification improves the accuracy of the methods by ~3 orders of magnitude, and the modified method of Uteshev and Goncharova (2018) achieves an accuracy of <0.1 mm anywhere on the surface of the Earth. The methods are especially efficient in the computation of ellipsoidal height. As an additional result of this study, a new formulation of the well-known method by Bowring (1976, Survey Review, 23: 323–327) is derived, and it is shown to improve the computation speed of Bowring's method by ~12%–~27% compared to the conventional formulation
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