2,425 research outputs found
Discuss Data: Community-zentrierter Ansatz für das Forschungsdatenmanagement in den Geistes- und Sozialwissenschaften
No full textDieser Artikel stellt einen Community-zentrierten Ansatz für das Forschungsdatenmanagement in den Geistes- und Sozialwissenschaften vor, der Daten explizit in einen Kontext zu ihrer Generierung, Nutzung und Кuratierung durch die entsprechenden Communities von Forschenden setzt. Discuss Data1 baut darauf auf und bildet eine Disziplin- und Methoden-übergreifende Plattform für die Regionalstudien zur post-sowjetischen Region. Aufbauend auf vorhandene FDM-Dienste, etwa zur Authentifizierung, Datenspeicherung und -registrierung, bietet Discuss Data die Möglichkeit Datenbeschreibungen kollaborativ zu bearbeiten, unter Verwendung verschiedener Lizenzmodelle dauerhaft zu publizieren und zu diskutieren. Mittelfristiges Ziel ist die Schaffung eines Kommunikationsortes rund um Forschungsdaten, der von allen interessierten Forschungscommunities nicht nur aktiv genutzt, sondern auch redaktionell getragen und konzeptionell weiter entwickelt werden kann. Diese Publikation ist entstanden im Rahmen des Discuss Data-Projektes, gefördert durch die Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 323616639
Faculty Spotlight 2008-09 Richard Herrmann
No full textMershon Center for International Security Studies Faculty Spotlight 2008-09The University Archives has determined that this item is of continuing value to OSU's history.Richard Herrmann is director of the Mershon Center for International
Security Studies. Since 2002, he has led the center's efforts to attract a
world-class faculty, establish its reputation as a leader in security studies,
and offer special opportunities to enhance the student experience.
Herrmann specializes in international relations, security and conflict
studies, political psychology, and politics in the Middle East and Russia.
He has written on the role of perception and imagery in foreign policy and
the importance of nationalism and identity politics. He is the author or
editor of three books and more than 40 articles in such journals as
American Political Science Review, International Organization,
International Security, and World Politics
Quantitative tools for seismic stratigraphy and lithology characterization
No full textSeismological images represent maps of the earth's structure. Apparent bandwidth limitation of seismic data prevents successful estimation of transition sharpness by the multiscale wavelet transform. We discuss the application of two recently developed techniques for (non-linear) singularity analysis designed for bandwidth limited data, such as imaged seismic reflectivity.
The first method is a generalization of Mallat's modulus maxima approach to a method capable of estimating coarse-grained local scaling/sharpness/Hölder regularity of edges/transitions from data residing at essentially one single scale. The method is based on a non-linear criterion predicting the (dis)appearance of local maxima as a function of the data's fractional integrations/differentiations.
The second method is an extension of an atomic decomposition technique based on the greedy Matching Pursuit Algorithm. Instead of the ordinary Spline Wavelet Packet Basis, our method uses multiple Fractional Spline Wavelet Packet Bases, especially designed for seismic reflectivity data. The first method excels in pinpointing the location of the singularities (the stratigraphy). The second method improves the singularity characterization by providing information on the transition's location, magnitude, scale, order and direction (anti-/causal/symmetric). Moreover, the atomic decomposition entails data compression, denoising and deconvolution.
The output of both methods produces a map of the earth's singularity structure. These maps can be overlayed with seismic data, thus providing us with a means to more precisely characterize the seismic reflectivity's litho-stratigraphical information content.Massachusetts Institute of Technology. Industry Consorti
Multi-And Monoscale Attributes For Well And Seismic Data
No full textEdges in a medium are the primary source of coherent reflections because they exhibit a
large or even diverging amplitude behavior for their derivatives. Generally the medium
properties are not only assumed to jump across interfaces, limiting the edge's singular
behavior to that of a jump discontinuity, but the interfaces are also assumed to be well
separated. Multiscale analysis on well data shows that the model of a jump discontinuity
is too limited to account for the scaling behavior displayed by these types of data
sets across the seismic scale range. It also demonstrates that the edges are not well
separated. These observations coined two generalizations. First the jump is generalized
to a wider class of scale exponent indexed transitions of which the jump is a special case. Secondly the edges are allowed to accumulate. The first part of this paper is devoted to the substantiation of these two generalizations. It introduces the necessary tools for the multiscale analysis, which characterizes the individual edges by means of scaling exponents and the overall texture by singularity spectra. The first part is concluded with a discussion on the application to well and seismic data.
In the second part a complementary method to obtain information on the scaling
is proposed. It is aimed to deal with the unfortunate fact that the scale content of the
seismic signal is relatively small, making it difficult to conduct the multiscale analysis. For instance it is hard to obtain estimates for the local scaling exponents, characterizing the different types of transitions via their induced reflectivity. The novel method presented uses fractional differentiations/integrations to estimate the scale exponents at a fixed scale.
The estimated scale exponents not only capture the local scaling characteristics but
are also related to the local frequency behavior of the reflections. In this capacity they constitute local stratigraphical texture parameterizations. Local texture is relevant for the identification of the major geological markers as well as for localization and characterization of the major channels and barriers for the fluid flow being all important characteristics for the reservoir. Multifractal singularity spectra, on the other hand, provide more general information on the global texture and they are highly relevant for geological sequences and for the properties of the reservoir rock
Seismic Facies Characterization By Scale Analysis
No full textOver the years, there has been an ongoing struggle to relate well-log and seismic data due to the inherent bandwidth limitation of seismic data, the problem of seismic amplitudes, and the apparent inability to delineate and characterize the transitions that can be linked to and held responsible for major reflection events and their signatures. By shifting focus to a scale invariant sharpness characterization for the reflectors, we develop a method that can capture, categorize, and reconstruct the main features of the reflectors, without being sensitive to the amplitudes. In this approach, sharpness is defined as the fractional degree of differentiability, which refers to the order of the singularity of the transitions. This sharpness determines mainly the signature/waveform of the reflection and can be estimated with the proposed monoscale analysis technique. Contrary to multiscale wavelet analysis the monoscale method is able to find the location and sharpness of the transitions at the fixed scale of the seismic wavelet. The method also captures the local orders of magnitude of the amplitude variations by scale exponents. These scale exponents express the local scale-invariance and texture. Consequently, the exponents contain local information on the type of depositional environment to which the reflector pertains. By applying the monoscale method to both migrated seismic sections and welllog data, we create an image of the earth's local singularity structure. This singularity map facilitates interpretation, facies characterization, and integration of well and seismic data on the level of local texture.Massachusetts Institute of Technology. Borehole Acoustics and Logging ConsortiumMassachusetts Institute of Technology. Earth Resources Laboratory. Reservoir Delineation
Consortiu
Scaling And Seismic Reflectivity: Implications Of Scaling On Avo
No full textAVO analysis of seismic data is based on the assumption that transitions in the earth
consist of jump discontinuities only. The generalization of this type of transition to a
more realistic class of transitions shows a drastic change in observed AVO behavior, especially for the large angles currently attained by increasing cable lengths. We propose a simple approach that accounts for this anomalous behavior by renormalizing the observed AVO. This renormalization allows for a separation of the observed AVO effects in
terms of a conventional Zoeppritz contribution and a scaling contribution in those cases
where the transitions can no longer be considered as isolated jump discontinuities. After
renormalization, the inverted fluctuations regain their relative magnitudes which, due
to the scaling, may have been significantly distorted. An example of these distortions
are tuning effects, often erroneously interpreted as bright spots.Massachusetts Institute of Technology. Borehole Acoustics and Logging ConsortiumMassachusetts Institute of Technology. Earth Resources Laboratory. Reservoir Delineation
Consortiu
Ueber das Product der Einwirkung von Alkalimetallen auf Bernsteinsäure-Aethylester
No full textvon Felix Herrman
Wavelet Domain Geophysical Inversion
No full textWe present a non-linear method for solving linear inverse problems by thresholding coefficients in the
wavelet domain1. Our method is based on the wavelet-vaguelette decomposition of Donoho (1992).
Numerical results for a synthetic travel-time inversion problem show that the wavelet based method
outperforms traditional least-squares methods of solution.Massachusetts Institute of Technology. Earth Resources Laborator
Multifractional splines: from seismic singularities to geological transitions
No full textA matching pursuit technique in conjunction with an imaging method is used to obtain quantitative
information on geological records from seismic data. The technique is based on a greedy, non-linear
search algorithm decomposing data into atoms. These atoms are drawn from a redundant dictionary
of seismic waveforms. Fractional splines are used to define this dictionary, whose elements are not only
designed to match the observed waveforms but also to span the appropriate family of geological patterns.
Consequently, the atom’s parameterization provides localized scale, order and direction information that
reveals the stratigraphy and the type of geological transitions. Besides a localized scaling characterization,
the atomic decomposition allows for an accurate denoised reconstruction of data with only a small number
of atoms. Application of this approach to angles gathers allows us to track geological singularities from
seismic data. Our characterization bridges the gap between the analysis of the main features within
geologic processes, i.e. the geologic patterns, and the interpretation of their associated seismic response.
A case study of Valhall data is presented.Massachusetts Institute of Technology. Earth Resources Laborator
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