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Felix Almaraz, Author and Teacher, "The Tragic Calvalier."(photograph)
No full textPhotograph of Felix Almaraz, Author and Teacher, "The Tragic Calvalier."
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
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
Parents’ assets and child marriage: are mother’s assets more protective than father’s assets?
No full textChild marriage places girls at an increased risk for dropping out of school early, sexually transmitted infections, teenage childbirth, and accompanying childbirth complications, including maternal mortality. The determinants of child marriage are not clearly understood, which hinders efforts to mount effective interventions. This study examined the link between economic resources and child marriage by investigating whether maternal and paternal asset ownership were longitudinally associated with daughters’ child marriage in Ethiopia. Drawing upon household bargaining theory, it was hypothesized that maternal assets would be more protective of daughters’ child marriage than paternal assets. Data for 4,293 girls from the nationally representative Ethiopia Socioeconomic Survey, fielded in 2011 and 2014, were employed. Logistic regression and instrumental variable analyses were used to examine the relationship between transition into child marriage during the study period and maternal and paternal assets, controlling for child-, family-, and community-level characteristics. Results show that a one standard deviation increase in mother’s assets was associated with 37–53% lower odds of daughter’s child marriage whereas a one standard deviation increase in paternal asset holdings was associated with 0–37% higher odds of daughter’s child marriage. Effects were strongest in regions where the dominant mode of marriage payments is bride price. These results suggest that the link between economic resources and child marriage depends on the gender of the parent who owns the resources. This study also highlights the interconnectedness of two targets of the gender equality Sustainable Development Goal—improvement of women’s ownership of assets and the elimination of child marriage—and suggests that the realization of one gender equality target could have implications for other targets.Peer reviewe
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
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