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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Nichtlineare statistische Methoden zur Datenanalyse /

Voss, Henning U. January 1999 (has links) (PDF)
Univ., Diss.--Potsdam, 1998.

Influence of database complexity and diversity on global crop suitability

Avellan, Tamara 28 May 2014 (has links) (PDF)
No description available.

Tectonogeomorphological and satellite image analysis of the Red Sea passive margin at the latitude of Wadi Siatin, Northern Quseir, Egypt

Elkhashab, Mohamed 11 June 2014 (has links) (PDF)
Remote sensing has become an essential tool to improve data collection and spatial analysis in the geosciences. Identification of passive margin structures that are exposed along the Egyptian coast of the Red Sea, and their control on landforms has been hampered by limited data resolution and restricted access to this arid and inaccessible region. A major challenge lies in distinguishing features in the landscape that formed due to long-term tectonic activity and erosion from those features that modified the landscape recently. The goals of this thesis were to determine to what degree the study area is currently tectonically active, and what major hazards might affect the touristically developing coastal region. This study deals with the structural and geomorphological evolution of the rift-related structures and their impact on the sediment distribution and landforms variation in the northern Quseir area. In such a remote desert area, field and remote morphostructural analysis are needed to understand the structural and geomorphological evolution. The current study is mainly based on high-resolution QuickBird image analysis and field investigation. Field mapping was limited to one season, owing to acute safety concerns in the Eastern Desert. In the study area, the pre-rift stratigraphy includes Pan-African basement rocks overlain by pre-rift clastic and carbonate successions that range in age from Cambrian to Eocene. Syn-rift clastic and carbonate rocks range in age from Late Oligocene to recent and show depositional patterns controlled by fault systems. The field area exposes a section of a tectonically uplifted, amagmatic sedimentary sequence, which formed due to passive-margin-related rifting of the Red Sea: the Mesozoic and Tertiary sedimentary units that fill the 7-km wide coastal strip are perfectly exposed as tilted fault blocks. The results of my field mapping and structural analysis show that the fault architecture of the area is dominated by a large NW-SE-striking fault system. A series of SE-dipping normal faults are consistent in cross-section with listric fault geometry, rooting into an E-dipping detachment at depth. Our mapping also revealed that left-steps in at least one of the major NS- striking faults are accommodated by a flower structure, but not by SW-NE-oriented cross faults as previously proposed in a neighboring area. Thus seismic activity is more likely to occur on the large NW-striking normal faults, leading to potentially larger Magnitude earthquakes than previously recognized in the area. The left-step may act as a barrier to rupture propagation and should be examined in more detail. The northwestern Red Sea coast is part of the straight coastal segment that is generally characterized as seismically inactive. However, during the geological field mapping, I found evidence for Plio-/Pleistocene vertical coastal uplift, likely due to earthquake-related coastal and offshore faulting. Pliocene marine deposits emerged recently due to sea level-drop and earthquake-related uplift. Even the presence of up to five distinct Pleistocene coral terraces implies that at least some of the coastal uplift was seismogenic, because terraces of the same age can be found at different elevations along strike. Presumably, some of the seawarddipping, N-S-striking normal faults are active today, despite the lack of recent instrumental seismicity. These findings imply long recurrence intervals for active faults in the northern Quseir area. These results differ from previously published results for the adjacent Quseir-Um Gheig sub-basin area, were E-W-striking strike-slip faults were mapped to offset the N-Sstriking faults, and had been inferred as earthquake-generating faults by Abd El-Wahed et al. (2010). Based on our mapping, we postulate that the large rift-parallel normal faults are seismogenic. Drainage network evolution within the study area is often structurally controlled and the nature of these controls was examined in this study. The Wadi Siatin stream channel network is classified in a relatively simple way, based on the high-resolution satellite data, with dendritic, and rectangular considered the most fundamental channel geometries. It was possible to distinguish the different morphological elements of the network, as well as the anomalies that affect the patterns. This analysis revealed, in the northern Red Sea area basins, the existence of old structures whose successive reactivations have left their mark on the drainage network. Comparison of joint systems direction with the directions of the main trunk stream channel of Wadi Siatin shows that the channel is highly affected by tectonic jointing. First-order channels follow easily erodable faults. Investigations concerning the relationship of stream-flow orientation with geological structure in the Wadi Siatin Basin shows that, generally, the least influenced flows are those of first-order which are governed simply by the valley side slopes on which they developed. However, in certain geological and geomorphological situations, there are clear exceptions to this generalization. Certainly, locally, geological control of these small streams may be even higher than in many streams of higher order. In the peripheral parts of the Basin, expansion of drainage into the available space has obviously been easiest along lines of weakness and, as a consequence of this, streams of the first order come to exhibit a high degree of adjustment to the underlying structure. The maximum structural control is reached by the streams of the third order. Towards the higher orders, the influence of local structure becomes weaker.

Außerunterrichtliche Lernorte: Die (Weiter-)Entwicklung von Lernpfaden zu einem Netz von Geopunkten mit Hilfe der Geocache-Methode

Kisser, Thomas 04 June 2014 (has links) (PDF)
The study deals with the two main problems in geographical education: How to inform students about a spatial practicing learning and teaching and how to evaluate this form of learning in comparison to theoretical non spatial forms of learning. The classic form of spatial learning is the outdoor excursion. But there are some new and actual alternatives when realizing the former intended aims of a spatial learning, so for instance didactical pathways, field trips or field works, but also the new way of geocaching and learning by GPS when dealing with the themes of orientation or finding out points of geographic importance for explaining the genetic processes. The necessary skills can be combined to improve the success of learning and to maximize the motivation. The base of this motivation behavior is the existence of a hide and seek-game as a modern version of a scavenger hunt. This motivates the students and is furthermore the attraction of Geocaching. Methodical skills can also be trained very automatically during this search. The GPS devices are of common use in the daily life and its use may increase much more in the fu-ture and in geographical use, too. Nowadays the literature about this theme is merely descriptive and thematically reduced to the function of orientation. The first study describing the learning suc-cess of using GPS devices and Geocaches in geography class had been made by NEEB. She tested the variation of the competence of orientation in different old classes when examining the use of GPS devices and Geocaches. Even though GPS devices and Geocaches are very efficient for instructing the students’ competence of orientation there may be the question, in what forms and circumstances the learning can be done. The time and effort necessary to generate a didactical and educational trail has to be justified against the background of the achieved learning effect. Educational trails need students, walking outside of the schools, looking for information along teaching paths and learning by the results. This active experienced learning leads to a better understanding of the environment, the outdoor circumstances and the people living in this area. You can structure such educational trails by Geopoints, this means points of a special geographic interest. Geocaches can structure such paths didactically. These structuring points are GEOpoints. The tasks at such Geopoints are structured didactical as well. GPS devices and Geocaches are complementing one another. They fulfill an important function in geographic orientation and the respective local information. Two important ministries in Germany (Bavaria, Baden-Württemberg) demand the use of extra¬curri-cu¬lar educational objectives in geography education. This means: visiting locations outside of the school and using the advantages of a fully learning by excursions. Neurobiology supports the idea that pupils completing the educational trail will learn much more and efficiently than students in “normal” classes: Indeed: A successful contextualization of modern geomedia stimulates the motivation. Geocaches are suitable for didactical structuration and motivation. A better and more comprehensive addressing to all senses will lead to a better sustainability. When testing the advantage of excursional learning comparing the same themes with a classical learning at school you have to differ within the students capacity of learning and the cognitive and methodical competence. For 17years aged students the theme of “Umgestaltung von Flusslandschaften“ (rearrangements of fluvial topography) was chosen because using this example of anthropogenic rearrangements of the Rheinaue wetlands near Karlsruhe shows the interdependency between human and environment was in the direct neighborhood of the students. Therefore the excursion could be realized very good without long transports. The “Nördlinger Ries” between the Swabian and the Franconian Jura is an impact-crater of world-wide importance. This location had been chosen for Students of grade 5 (10 years old students). The themes to work out were: The typical elements of the Swabian Jura (karst formation, hydrogeology, typical vegetation) and the special forms of the impact tectonics. The sustainability of educational trails using GPS had been evaluated by the answers of 441 ques-tionnaires. In grade 5 a multiple-choice-test had to be answered while grade 11 had to answer open questions in complete sentences. The influence of the teachers on the overall result is being kept low through the random selection, the number of the comparison groups and the teaching manuals. The overall results of these questionnaires show that the students of grade 5 which completed the educations trail achieved 11% higher scores in areas of the cognitive performance compared to the students who experienced classical learning at school. In grade 11 the students who completed the educational trail received 5% higher scores. Both differences in the results are significant and show a magnitude of effect, which is high in certain items. Consequently, the study has proven that educational trails evocate better cognitive performances than classical learning at school. The current state of research suggests that the development of environmental trails from teachers for teachers is not sustainable because the teachers don’t have the time to refine environmental trails didactically. The experience while creating the educational trails and the feedback of the participant teachers showed that teachers should cooperate for creating educational trails. The strain for each single person is reduced and the regularly use of the educational trails can be assured.

Reducing non-uniqueness in seismic inverse problems

Bernauer, Moritz 10 July 2014 (has links) (PDF)
The scientific investigation of the solid Earth's complex processes, including their interactions with the oceans and the atmosphere, is an interdisciplinary field in which seismology has one key role. Major contributions of modern seismology are (1) the development of high-resolution tomographic images of the Earth's structure and (2) the investigation of earthquake source processes. In both disciplines the challenge lies in solving a seismic inverse problem, i.e. in obtaining information about physical parameters that are not directly observable. Seismic inverse studies usually aim to find realistic models through the minimization of the misfit between observed and theoretically computed (synthetic) ground motions. In general, this approach depends on the numerical simulation of seismic waves propagating in a specified Earth model (forward problem) and the acquisition of illuminating data. While the former is routinely solved using spectral-element methods, many seismic inverse problems still suffer from the lack of information typically leading to ill-posed inverse problems with multiple solutions and trade-offs between the model parameters. Non-linearity in forward modeling and the non-convexity of misfit functions aggravate the inversion for structure and source. This situation requires an efficient exploitation of the available data. However, a careful analysis of whether individual models can be considered a reasonable approximation of the true solution (deterministic approach) or if single models should be replaced with statistical distributions of model parameters (probabilistic or Bayesian approach) is inevitable. Deterministic inversion attempts to find the model that provides the best explanation of the data, typically using iterative optimization techniques. To prevent the inversion process from being trapped in a meaningless local minimum an accurate initial low frequency model is indispensable. Regularization, e.g. in terms of smoothing or damping, is necessary to avoid artifacts from the mapping of high frequency information. However, regularization increases parameter trade-offs and is subjective to some degree, which means that resolution estimates tend to be biased. Probabilistic (or Bayesian) inversions overcome the drawbacks of the deterministic approach by using a global model search that provides unbiased measures of resolution and trade-offs. Critical aspects are computational costs, the appropriate incorporation of prior knowledge and the difficulties in interpreting and processing the results. This work studies both the deterministic and the probabilistic approach. Recent observations of rotational ground motions, that complement translational ground motion measurements from conventional seismometers, motivated the research. It is investigated if alternative seismic observables, including rotations and dynamic strain, have the potential to reduce non-uniqueness and parameter trade-offs in seismic inverse problems. In the framework of deterministic full waveform inversion a novel approach to seismic tomography is applied for the first time to (synthetic) collocated measurements of translations, rotations and strain. The concept is based on the definition of new observables combining translation and rotation, and translation and strain measurements, respectively. Studying the corresponding sensitivity kernels assesses the capability of the new observables to constrain various aspects of a three-dimensional Earth structure. These observables are generally sensitive only to small-scale near-receiver structures. It follows, for example, that knowledge of deeper Earth structure are not required in tomographic inversions for local structure based on the new observables. Also in the context of deterministic full waveform inversion a new method for the design of seismic observables with focused sensitivity to a target model parameter class, e.g. density structure, is developed. This is achieved through the optimal linear combination of fundamental observables that can be any scalar measurement extracted from seismic recordings. A series of examples illustrate that the resulting optimal observables are able to minimize inter-parameter trade-offs that result from regularization in ill-posed multi-parameter inverse problems. The inclusion of alternative and the design of optimal observables in seismic tomography also affect more general objectives in geoscience. The investigation of the history and the dynamics of tectonic plate motion benefits, for example, from the detailed knowledge of small-scale heterogeneities in the crust and the upper mantle. Optimal observables focusing on density help to independently constrain the Earth's temperature and composition and provide information on convective flow. Moreover, the presented work analyzes for the first time if the inclusion of rotational ground motion measurements enables a more detailed description of earthquake source processes. The complexities of earthquake rupture suggest a probabilistic (or Bayesian) inversion approach. The results of the synthetic study indicate that the incorporation of rotational ground motion recordings can significantly reduce the non-uniqueness in finite source inversions, provided that measurement uncertainties are similar to or below the uncertainties of translational velocity recordings. If this condition is met, the joint processing of rotational and translational ground motion provides more detailed information about earthquake dynamics, including rheological fault properties and friction law parameters. Both are critical e.g. for the reliable assessment of seismic hazards.

Structure determination of piezoelectric materials at extreme conditions

Pavlovska, Anzhela 04 July 2002 (has links) (PDF)

Struktur und Wachstum von Surfactants auf einer Ge(113)-Oberfläche

Hirnet, Alexander 08 July 2002 (has links) (PDF)
No description available.

Möglichkeiten eines DMO-Prozesses in der CMP-Refraktionsseismik

Gawlas, Peter Florian 14 June 2002 (has links) (PDF)

Monitoring of Plant Chlorophyll and Nitrogen Status Using the Airborne Imaging Spectrometer AVIS

Oppelt, Natascha 12 July 2002 (has links) (PDF)
HASH(0x60c9800) / HASH(0x61d1750)

Moving hotspots

Antretter, Maria 25 July 2001 (has links) (PDF)
HASH(0x6012b10) / HASH(0x5f87388)

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