Mathematisch-Naturwissenschaftliche Fakultät: Auflistung Mathematisch-Naturwissenschaftliche Fakultät nach Titel
Anzeige der Dokumente 21-40 von 4592
-
A molecular dynamics study on fullerene–implanted carbon nanotori as electronmagnetic sensing and emitting devices
Griebel, Michael; Heber, Frederik (2009-10)Open-ended carbon nanotubes have been found to form toroidal structures [17]. These specific structures bear striking resemblance to electrographic coils. Two modes of action can be thought of: Either the metallic conductivity ... -
A molecular dynamics study on the impact of defects and functionalization on the Young modulus of boron-nitride nanotubes
Griebel, Michael; Hamaekers, Jan; Heber, Frederik (2007)In this article, we examine the Young modulus of (6, <em>m</em>) boron-nitride nanotubes with vacancy and functionalization defects. We employ molecular dynamics simulations using the Parrinello-Rahman approach. To this ... -
A multilevel approach to the evolutionary generation of polycrystalline structures
Barker, James; Bollerhey, Gregor; Hamaekers, Jan (2015-11)The Poisson-Voronoi tesselation is commonly used as an approximation to the microstructure of polycrystalline material. Although simple, this approximation fails to respect basic physical properties observed empirically, ... -
A multiscale finite element method for Neumann problems in porous microstructures
Brown, Donald L.; Taralova, Vasilena (2015-01)In this paper we develop and analyze a Multiscale Finite Element Method (MsFEM) for problems in porous microstructures. By solving local problems throughout the domain we are able to construct a multiscale basis that can ... -
A multiscale method for porous microstructures
Brown, Donald L.; Peterseim, Daniel (2014-11)In this paper we develop a multiscale method to solve problems in complicated porous microstructures with Neumann boundary conditions. By using a coarse-grid quasi-interpolation operator to define a fine detail space and ... -
A new discretization for mth-Laplace equations with arbitrary polynomial degrees
Schedensack, Mira (2016-07)This paper introduces new mixed formulations and discretizations for <em>m</em>th-Laplace equations of the form (−1)<em><sup>m</sup></em>∆<em><sup>m</sup>u</em> = f for arbitrary <em>m</em> = 1, 2, 3, . . . based on novel ... -
A new generalization of the P1 non-conforming FEM to higher polynomial degrees
Schedensack, Mira (2015)This paper generalizes the non-conforming FEM of Crouzeix and Raviart and its fundamental projection property by a novel mixed formulation for the Poisson problem based on the Helmholtz decomposition. The new formulation ... -
A note on source term representation for control-and-state-constrained parabolic control problems with purely time-dependent control
Neitzel, Ira (2022-06)We revisit the concept of source term representation, originally developed for boundary control problems subject to pointwise state constraints in the domain, and apply it to linear-quadratic parabolic control problems ... -
A note on the construction of L-fold sparse tensor product spaces
Griebel, Michael; Harbrecht, Helmut (2012-04)In the present paper, we consider the construction of general sparse tensor product spaces in arbitrary space dimensions when the single subdomains are of different dimensionality and the associated ansatz spaces possess ... -
A sparse grid based generative topographic mapping for the dimensionality reduction of high-dimensional data
Griebel, Michael; Hullmann, Alexander (2012-05)Most high-dimensional data exhibit some correlation such that data points are not distributed uniformly in the data space but lie approximately on a lower-dimensional manifold. A major problem in many data-mining applications ... -
A sparse grid based method for generative dimensionality reduction of high-dimensional data
Bohn, Bastian; Garcke, Jochen; Griebel, Michael (2015-11)Generative dimensionality reduction methods play an important role in machine learning applications because they construct an explicit mapping from a low-dimensional space to the high-dimensional data space. We discuss a ... -
A wavelet based sparse grid method for the electronic Schrödinger equation
Griebel, Michael; Hamaekers, Jan (2006-05)We present a direct discretization of the electronic Schrödinger equation. It is based on one-dimensional Meyer wavelets from which we build an anisotropic multiresolution analysis for general particle spaces by a tensor ... -
A-posteriori error estimation of discrete POD models for PDE-constrained optimal control
Gubisch, Martin; Neitzel, Ira; Volkwein, Stefan (2016-03)In this work a-posteriori error estimates for linear-quadratic optimal control problems governed by parabolic equations are considered. Different error estimation techniques for finite element discretizations and model-order ... -
A-posteriori reduced basis error-estimates for a semi-discrete in space quasilinear parabolic PDE
Hoppe, Fabian; Neitzel, Ira (2020-12)We prove a-posteriori error-estimates for reduced-order modeling of quasilinear parabolic PDEs with non-monotone nonlinearity. We consider the solution of a semi-discrete in space equation as reference, and therefore ... -
A2B-Adenosin-Rezeptor-Homo- und Heterodimere: Biolumineszenz-Resonanz-Energie-Transfer-Studien und pharmakologische Charakterisierung
Seibt, Benjamin F. (2012-12-12)Die Adenosin-Rezeptoren, welche zur Superfamilie der G-Protein-gekoppelten Rezeptoren (GPCR) gehören, werden in die vier Subtypen, A<sub>1</sub>, A<sub>2A</sub>, A<sub>2B</sub> und A<sub>3</sub> unterteilt. Aufgrund der ... -
Ab-initio Untersuchungen an Aluminium, seinen Defekten und Aluminium-Legierungen
Röbel, Michael (2005)Ziel dieser Arbeit war die Untersuchung von Kristallstrukturen und deren Defekte in Hinblick auf die experimentelle Nachweisbarkeit mit Positronenlebensdauer - Spektroskopie. Die Untersuchungen der Kristallstrukturen wurden ... -
Ab-initio Untersuchungen an frühen Ausscheidungsphasen der Aluminium(-Magnesium-)Kupfer-Legierungen
Wolfertz, Iris (2015-07-23)Frühe Ausscheidungscluster der AlCu-Legierungen und der AlMgCu-Legierungen werden mit numerischen ab-initio Methoden mit Hilfe des DFT-Programmcodes SIESTA untersucht. Cu-Atome favorisieren innerhalb der AlCu-Legierungen ... -
ABA-Dependent and -Independent Regulation of Tocopherol (Vitamin E) Biosynthesis in Response to Abiotic Stress in Arabidopsis
Kreszies, Victoria (2019-05-15)Abiotic stresses in plants lead to elevated levels of reactive oxygen species that can have detrimental effects on photosystems and thylakoid lipids. To limit damage, plants increase the production of antioxidants such as ... -
Abbildende Spektroskopie erosionsrelevanter Bodenparameter in Agrarökosystemen
Gerighausen, Heike (2013-01-23)Die Vielzahl der Funktionen, die der Boden in einem Ökosystem übernimmt, verleiht ihm einen hohen Stellenwert im Mensch-Umwelt-System. Der Boden landwirtschaftlicher Nutzflächen ist im Besonderen eine elementare Säule der ... -
Abbildung und farbtonbasierte Analyse ausgedehnter neuronaler Strukturen
Heysel, Jana Lisa (2021-08-03)Der Hippocampus ist eine Gehirnregion im mittleren Temporallappen, welcher für die Formung des expliziten Gedächtnisses zuständig ist. Lange Zeit galt der Dentatus Gyrus (DG), eine Region im Hippocampus, als “Eingang“ für ...