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Freiberg, Germany

The Technische Universität Bergakademie Freiberg is a small German University of Technology with about 6000 students in the city of Freiberg, Saxony. It was established in 1765, by Prince Franz Xaver, regent of Saxony, based on plans by Friedrich Wilhelm von Oppel and Friedrich Anton von Heynitz, and is the oldest university of mining and metallurgy in the world. The chemical elements Indium and Germanium were discovered by scientists of Freiberg University. The polymath Alexander von Humboldt studied mining at the Bergakademie Freiberg in 1791/1792. Nowadays TU Bergakademie Freiberg is a Technical university with 6 faculties are without tuition fees; students pay only a registration fee of about 70 € per semester. Wikipedia.

Morais J.,TU Bergakademie Freiberg
Mathematical and Computer Modelling

The object of this paper is to construct a complete orthogonal system of monogenic polynomials as solutions of the Moisil-Théodoresco system over prolate spheroids in R3. This will be done in the spaces of square integrable functions over H. A big breakthrough is that the orthogonality of the polynomials in question does not depend on the shape of the spheroids, but only on the location of the foci of the ellipse generating the spheroid. The representations of these polynomials are given explicitly, ready to be implemented on a computer. In addition, we show a corresponding orthogonality of the same polynomials over the surface of the spheroids with respect to a suitable weight function. © 2012 Elsevier Ltd. Source

Ji L.,TU Bergakademie Freiberg | Schuurmann G.,Helmholtz Center for Environmental Research
Angewandte Chemie - International Edition

Only one path applies: To date, five different mechanisms have been suggested for the P450-catalyzed N-hydroxylation of primary aromatic amines. Computational analysis employing density functional theory demonstrates that only the H-atom-transfer pathway, that is H abstraction from an amine N followed by a radical rebound step, on a low-spin route can contribute to the aromatic hydroxylamine formation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Borner R.-U.,TU Bergakademie Freiberg
Surveys in Geophysics

During the last decade, tremendous advances have been observed in the broad field of numerical modelling for geo-electromagnetic applications. This trend received support due to increasing industrial needs, mainly caused by hydrocarbon and ore exploration industry. On the other hand, the increasing reliability and accuracy of data acquisition techniques further spurs this development. In this review, we will focus on advances and challenges in numerical modelling in geo-electromagnetics. We review recent developments in the discrete solution of the 3-D induction problem in the time and frequency domains. Particularly, advantages and disadvantages of the common numerical techniques for solving partial differential equations such as the Finite Difference and Finite Element methods will be considered. © Springer Science+Business Media B.V. 2009. Source

Kuna M.,TU Bergakademie Freiberg
Engineering Fracture Mechanics

Piezoelectric and ferroelectric materials have gained extensive applications in electromechanical devices, microelectromechanical systems and smart composite materials. In order to assess the strength and durability of those materials and components, exhaustive theoretical and experimental investigations have been performed over the past three decades. The aim of the paper is to give a short overview and a critical discussion about the present state in the field of piezoelectric fracture mechanics. After an introduction, linear piezoelectric fracture theory is explained with emphasis to special features like anisotropy, mode mixture and electric properties of cracks. Next, suggested fracture criteria are presented and contrasted with experimental observations in fracture testing. Cracks under static, cyclic and dynamic loading by electrical and mechanical fields are taken into account. A great challenge is to tackle the non-linear phenomena and ferroelectric domain switching in the fracture process zone. Finally, conclusions are drawn with respect to open problems and desirable future research areas. To limit the scope of the paper, fracture behavior of interface cracks will not be addressed. © 2009 Elsevier Ltd. All rights reserved. Source

Kroner U.,TU Bergakademie Freiberg | Romer R.L.,German Research Center for Geosciences
Gondwana Research

The Variscides of Europe and N-Africa are the result of the convergence of the plates of Gondwana and Laurussia in the Paleozoic. This orogen is characterized by the juxtaposition of blocks of continental crust that are little affected by the Variscan orogeny. These low strain domains principally consist of Neoproterozoic/Cambrian Cadomian basement overlain by volcano-sedimentary successions of an extended peri-Gondwana shelf. These Cadomian blocks are separated by high strain zones containing the record of subduction-related processes. Traditionally the high strain zones are interpreted as sutures between one or more postulated lithospheric microplates sandwiched between the two major plates. Paleobio-geographic constraints in combination with geochemical and isotopic fingerprints of the protoliths, however, imply that the Variscides are the result of the exclusive interaction of the two plates of Gondwana and Laurussia. Here we explain the Variscan orogen in a two plate scenario, reasoning that the complexity of the Variscan orogen (multitude of high-grade metamorphic belts, compositional diversity of coeval magmatism, and arrangement of foreland basins) is the result of the distribution of crustal domains of contrasting rheological properties. Post-Cadomian rifting along the Cadomian-Avalonian belt, which culminated in the opening of the Rheic Ocean, resulted in vast coeval intracontinental extension and the formation of extended peri-Gondwana shelf areas, namely the Avalonian shelf and the Armorican Spur to the north and south of the evolving Rheic Ocean, respectively. Both shelf areas affected by heterogeneous extension consist of stable continental blocks separated by zones of thinner continental crust. During Variscan collisional tectonics the continental blocks behave as unsubductable crust, whereas the thinner continental crust was subductable and came to constitute the high strain domains of the orogen. The variable interplay between both crustal types in space and time is seen as the principal cause for the observed sequence of orogenic processes. The first collisional contact along the convergent Gondwana-Laurussia plate boundary occurred between Brittany and the Midland microcraton causing the early Devonian deformation along the Anglo-Brabant Fold Belt. This process is coeval with the initiation of continental subduction along the Armorican Spur of the Gondwana plate and the formation of back arc and transtensional basins to both sides of the Armorican Spur (e.g., Lizard, Rheno-Hercynian, Careón, Sleza) on the Laurussia plate. As further subduction along this collision zone is blocked, the plate boundary zone between the Gondwana and Laurentia plates is reorganized, leading to a flip of the subduction polarity and a subduction zone jump outboard of the already accreted blocks. The following Devonian-Early Carboniferous subduction accretion process is responsible for the juxtaposition of additional Cadomian blocks against Laurussia and a second suite of high-pressure rocks. The final collision between Gondwana and Laurussia is marked by an intracontinental subduction event affecting the entire internal zone of the orogen. Subduction stopped at 340. Ma and the following isothermal exhumation of the deeply subducted continental crust is primarily responsible for Late Variscan high-temperature metamorphism and cogenetic voluminous granitic magmatism. During this final transpressional stage the irregular shape of the Variscan orogen was established by the highly oblique motion of the decoupled lithospheric blocks (e.g. Iberia and Saxo-Thuringia). Rapid overfilling of synorogenic marine basins in the foreland and subsequent folding of these deposits along vast external fold and thrust belts finally shaped the Variscides, feigning a relatively simple architecture.In terms of plate tectonics, the model places the opening of the Paleotethys in the Devonian with a rotational axis of the spreading center just east of the Variscan orogen. The movement of Gondwana relative to Laurussia follows small circle paths about this axis from 370 to 300. Ma. As a consequence of the incomplete closure of the Rheic Ocean after the termination of the Variscan orogeny, Gondwana decoupled from the European Variscides along the dextral Gibraltar Fault Zone. The relative motion between Gondwana and Laurussia after 300. Ma is associated with a shift of the rotational axis to a position close to the Oslo Rift, and is related to the opening of the Neotethys and the evolution of the Central European Extensional Province. The Permian convergence of Gondwana and Laurussia led to the final Permian collisional tectonics along the Mauritanides/Alleghanides. The assembly of the "Wegenerian" Pangea is complete by the end of the Paleozoic. © 2013 International Association for Gondwana Research. Source

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