cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
title: Eine Ader für die Mathematik: Modellierung und numerische Simulation der Arteriosklerose
Creators: name: Klawonn, Axel
name: Rheinbach, Oliver
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 510

description: Um ein besseres Verständnis der Arteriosklerose und ihrer Behandlung zu entwickeln, kooperieren Mathematiker mit Medizinern und Ingenieuren. Über diese interdisziplinäre Zusammenarbeit berichten die Mathematiker Axel Klawonn und Oliver Rheinbach.
description: Cardio-vascular diseases are the prime cause of death in the Western World. Arteriosclerotic plaques may lead to an obstruction of the blood flow and can cause heart attacks and strokes. In this context, balloondilatation and stenting are established treatments to dilate the artery again and keep it open. Nowadays, the two traditional principles of science, theory and experiment, are complemented by numerical simulations as a third principle. Simulations of the process of balloondilatation may help to gain medical insight. In a current research project in Essen anatomical and physiological data of the arterial wall necessary for such simulations are obtained from the fusion of ultrasound imaging and X-ray angiographic data. The resulting finite element model is large and solved on a parallel computer using a sophisticated algorithm, the so called FETI domain decomposition method. The latter method has been used in the past by mathematicians and engineers to solve large systems of equations on supercomputers. This project is a common effort of mathematical, medical and engineering scientists and is supported by the Deutsche Forschungsgemeinschaft.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 8
title: Editorial
Creators: name: von der Linde, Dietrich
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 000

description: UNIKATE: Berichte aus Forschung und Lehre, no. 32Naturwissenschaften - Physik: Energieumwandlungen an Oberflächen, p. 6
Solar energy usage at home
Creators: name: Shariatzadeh, Adonis
Publisher: name: The University of British Columbia
Year: 2012

description: This report investigates the applications of solar energy in buildings and households. Study of various energy sources and their impact on the environment explores the leading reasons for development of solar cells and portrays humans’ thirst for more efficient technologies. After extensive literary and quantitative reviews, the values in using solar energy have been revealed. Solar cells have been around for many years. Once the solar panels are installed on the building, the usage becomes simple. However, usage of solar energy is not limited to solar panels. Solar energy can be used to produce solar electricity, heating, cooling, and lighting. This energy source can be integrated onto the building during construction to ease the usage. This report emphasizes the main applications of solar energy at buildings and highlights the different methods to take advantage of this renewable source of energy.
title: Was man simulieren kann, das kann man auch optimieren...: Zur mathematischen Optimierung komplexer technologischer Prozesse
Creators: name: Rösch, Arnd
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 510

description: Der Wunsch nach Optimierung spielt in vielen Lebensbereichen eine wichtige Rolle. Moderne mathematische Verfahren können helfen, auch komplizierte industrielle Prozesse zu optimieren.
description: Optimization of processes described by differential equations is very important for industrial applications. Moreover, physical restrictions on the process leads to additional pointwise inequality constraints. The first part of this article is devoted to historical aspects. The famous problem of Dido from Karthago 2000 years ago was the first optimization problem for a function. Calculus of variation was founded 1696 by the work of Johann Bernoulli and others. However, the theory of optimization with differential equations is very young: The first paper of Boltyanskij, Gamkrelidze und Pontryagin was published in 1956. In the beginning, the theory of optimal controls was mainly devoted to systems of ordinary differential equations with applications in robotics or aeronautics. Meanwhile, optimization with differential equations is very important in a lot of different fields, for instance medicine, nanotechnology, or new materials. Discretization of the differential equations leads to large nonlinear optimization problems. The DFGpriority programme 1253 “Optimization with partial differential equations“ specifies the average number of optimization variables in such an optimization problem by 107 unknowns. Clearly, the solving of such huge problems is mathematically challenging. Whole classes of methods like genetic algorithms or gradient methods cannot be used for such problems. Highly specified active set strategies and interior point methods are suitable tools to attack discretized optimal control problems. Very important for the practical realization are discretization aspects. The ultimative goal is to solve such optimal control problems with a given accuracy at low costs. In the last years different strategies are developed to solve optimal control problems with a discretization of moderate size and high accuracy. Since optimal controls have usually kinks and other singularities, completely new strategies have to be developed.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 22
A Non-convex Optimization Approach of Searching Algebraic Degree Phase-type Representations for General Phase-type Distributions
Creators: name: Liu, Yujie
name: Yao, Dacheng
name: Zhang, Hanqin
Publisher: name: arXiv
Year: 2024
Subjects: subject: Optimization and Control (math.OC)
subject: Probability (math.PR)
subject: FOS: Mathematics

description: For a continuous-time phase-type distribution, starting with its Laplace-Stieltjes transform, we obtain a necessary and sufficient condition for its minimal phase-type representation to have the same order as the algebraic degree of the Laplace-Stieltjes transform. To facilitate finding this minimal representation, we transform this condition equivalently into a quadratic nonconvex optimization problem, which can be effectively addressed using an alternating minimization algorithm. The algorithm convergence is also proved. Moreover, the method we develop for the continuous-time phase-type distributions can be directly used to the discrete-time phase-type distributions after establishing an equivalence between the minimal representation problems for continuous-time and discrete-times phase-type distributions.
title: Der Widerstand eines Atoms: Elektromigration im Miniaturformat
Creators: name: Horn-von Hoegen, Michael
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 530

description: Mit dem immer weiter voranschreitenden Trend, Computer bei gleichzeitig zunehmender Leistungsfähigkeit schrumpfen zu lassen, wachsen die Herausforderungen an ihre Mini-Bauelemente. So sind die Milliarden von Transistoren auf einem Chip mit elektrischen Leiterbahnen aus Metallen wie Aluminium oder Kupfer verbunden. Aufgrund ihres schrumpfenden Querschnitts sind diese durch die so genannte Elektromigration gefährdet, die durch Streuung der Leitungselektronen an rauen Oberflächen zusätzlich verstärkt wird.
description: The electric resistance of very thin wires or films is affected by their surface. With decreasing dimensions electrons are not only scattered at bulk defects and lattice vibrations but also from defects at the surface as roughness, adsorbates or even single atoms. This effect becomes dominant when the diameter of a wire or the thickness of a film becomes smaller than the mean free path of the electrons between two scattering events which determines the electric resistance of a thick wire. We used ultra thin crystalline films of Silver on quasi insulating Silicon substrates in ultra high vacuum to study these effects under well controlled conditions. During additional deposition at temperatures below -100°C the surface becomes very rough and the resistance increases due to enhanced scattering of the electrons. This effect is even more drastic when we use Gold atoms, which forms an alloy with the silver film where electrons are strongly scattered. On ultra thin Bismuth films even the deposition of single isolated Bi atoms gave rise to a strong increase of the film resistance. This experiment allows determining the precise cross section of scattering for single atoms.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 32Naturwissenschaften - Physik: Energieumwandlungen an Oberflächen, p. 8
title: Mathematik und Romantik: Die Aphorismen des Novalis zur Mathematik
Creators: name: Jahnke, Hans
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 510

description: In der Frühphase der literarischen Bewegung der Romantik hat der Dichter Friedrich von Hardenberg (Novalis) in den Jahren 1798/99 Aphorismen über die Mathematik zu Papier gebracht. Diese waren als Teil einer „romantischen Enzyklopädie“ gedacht. Novalis’ Gedanken können nur adäquat verstanden werden, wenn man sie im Kontext der damaligen Mathematik betrachtet. Novalis hat seine mathematischen Kenntnisse aus Büchern bezogen, deren Autoren einer damals in Deutschland einflussreichen Gruppe von Mathematikern angehörten, die heute weitgehend vergessen sind. Der Beitrag stellt einige Aphorismen des Novalis vor und interpretiert sie exemplarisch. Dabei stellt sich heraus, dass sich Novalis’ Ideen als kulturelle Indikatoren eines tiefgehenden Epochenwandels in der Mathematik des 19. Jahrhunderts deuten lassen.
description: The poet Friedrich von Hardenberg (Novalis) wrote aphorisms about mathematics during the early period of the Romantic Movement in literature, in the years 1798/99. He intended to include them in a ‘romantic encyclopedia’. In order to understand Novalis’ ideas adequately, they have to be considered in the context of the mathematics of the time. Novalis obtained his mathematical knowledge from the work of a group of mathematicians who are almost entirely forgotten today. The paper presents and interprets some of Novalis’ aphorisms. Research shows that his ideas can be considered as cultural indicators of a fundamental change of view in 19th Century mathematics.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 30
title: Wie die Trägheit des Spins eine chemische Reaktion aus der Bahn wirft: die Oxidation von Aluminium (111)
Creators: name: Hasselbrink, Eckart
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 530

description: Der Verlauf chemischer Reaktionen von einfachen Molekülen mit Festkörperoberflächen – insbesondere deren Aktivierungsenergie – ist aufgrund neuer theoretischer Methoden mit guter Genauigkeit vorhersagbar geworden. Trotzdem gibt es Reaktionssysteme, bei denen diese Methoden versagen. Eines davon ist die dissoziative Adsorption von Sauerstoffmolekülen an einer Aluminium(111)-Oberfläche. Unsere Arbeiten zeigen, dass ein notwendiger Übergang des Elektronenspins die Reaktion behindert, was dazu führt, dass die Reaktion letztlich als Abstraktion erfolgt.
description: As new theoretical methods have been developed, the course of chemical reactions and in particular the activation energy of simple molecules with solid surfaces have become predictable with reasonable accuracy. Nevertheless, these methods fail in the case of some reaction systems, such as the dissociative adsorption of oxygen on an aluminium(111) surface. Our study demonstrates that the lack of a spin transition, which is required for the reaction to proceed, hinders the latter such that an abstraction pathway is favoured.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 32Naturwissenschaften - Physik: Energieumwandlungen an Oberflächen, p. 22
title: Kein Kinderspiel: Das Fünfzehner-Schiebepuzzle
Creators: name: Törner, Günter
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 510

description: Über das Fünfzehner-Schiebepuzzle, das nun wahrlich mehr als ein Kinderspiel ist und viel mit handfester Mathematik zu tun hat, berichtet der Beitrag von Günter Törner.
description: The puzzle is a popular topic for books on recreational mathematics, most of which use it as an example to illustrate the consequences of even and odd permutations. Most references to the 15-puzzle explain the impossibility of obtaining odd permutations, and many state the classical result that every even permutation is indeed possible, however complete proofs are rare. Indeed, the famous mathematicians Herstein and Kaplansky wrote in 1978 that no really easy proof seems to be known. Archer’s (1999) paper set out to rectify that deficiency. Central to this is the algebraic result that the group An with n = 15 is generated by the consecutive 3-cycles which has to be justified by suitable placements in the puzzle. We adopted Archer‘s idea, modified his enumeration and implemented a cyclic numbering of the cells where the beginning and the end of the path is the blank cell. Using this method we are able to prove the classical result rather quickly. Further, we generalize the structure of the puzzle and make clear how the result can be extended to suitable polygonal graphs.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 42
title: Elektronenmikroskopie einmal anders: Mikroskopie mit ballistischen Elektronen
Creators: name: Möller, Rolf
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 530

description: Seit ihren Anfängen vor 350 Jahren öffnet die Mikroskopie mit ihren Entwicklungen den Naturwissenschaften immer wieder neue Türen. Die aktuellste Entwicklung – ergänzend zur Rastertunnelmikroskopie – ist die Mikroskopie mit ballistischen Elektronen, die so genannte Ballistische Elektronen Emissions Mikroskopie, die einen Einblick in die elektronischen Umlaufbahnen einzelner Moleküle erlaubt.
description: The development of microscopy has played and still plays a key role for science. The discovery of bacteria and viruses is one example. The various forms of electron microscopy enable to go far beyond the resolution of optical microscopy. With the invention of scanning probe microscopy about 25 years ago it became possible to image surfaces with atomic resolution. These techniques are based on the interaction of a local probe which is brought very close to the surface. In scanning tunneling microscopy the current of electrons between a very sharp metallic tip and the conducting surface provides a measure of the distance between tip and sample. For the standard applications only the total current matters. However, in a special configuration one can distinguish between those electrons which are scattered and loose energy, and those who traverse the configuration without significant energy loss, the latter are called “ballistic”. If this current of ballistic electrons is measured while imaging the surface, the ballistic transmission through individual objects may be analyzed. This new kind of transmission electron microscopy may become especially important for the development of future molecular based electronic devices with minimal energy dissipation.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 32Naturwissenschaften - Physik: Energieumwandlungen an Oberflächen, p. 30
title: Evolution: Von der Biologie zur Mathematik und wieder zurück: Die Ergebnisse der Evolutionstheorie sind heute nicht nur Naturbeschreibung, sondern auch mathematisches Werkzeug
Creators: name: Hoffmann, Daniel
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 004
subject: 570
subject: 510

description: Die Evolutionstheorie ist die grundlegende Beschreibung der Entwicklung biologischer Vielfalt. Ihre mathematische Formulierung hat viele Wissenszweige befruchtet und wird immer breiter eingesetzt. Mathematische Modelle der Evolution helfen beispielsweise bei der Entwicklung antiretroviraler Therapien und beim Design von Biomolekülen.
description: Evolution is both a concept in biology and an abstract optimization principle. In biology, evolution has for the first time rigorously explained how new species emerge from predecessor species. The process is iterative and involves the steps of mutation, selection, and replication of individuals. In the course of the process, species change towards an optimal adaptation to their environment. In this text, two current examples are given of application of evolutionary concepts. First, it is demonstrated how the adaptation of human immunodeficiency virus (HIV) to its host and to antiviral therapies can be modelled with evolutionary concepts such as the mutagenetic tree, a kind of phylogenetic tree of the viral genome focused on mutations relevant to resistance to antiviral therapies. It is shown how mutagenetic trees and mixtures thereof are used to quantify the longterm effectiveness of therapies in view of the possibility of the virus to develop resistance mutations. The second topic of the text is how virtual evolution in the computer can be used to optimize biomolecules. The concept of multi-objective optimization based on Pareto-dominance as fitness criterion is introduced as it promises to provide solutions to real-world optimization problems with multiple independent fitness requirements.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 54
title: Momentbilder atomarer Strukturen: den Tanz der Atome in Zeitlupe betrachten
Creators: name: von der Linde, Dietrich
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 530

description: Kurzwellige Strahlung, insbesondere Röntgenstrahlung, wird seit langer Zeit dazu verwendet, die atomare Struktur von Materie zu untersuchen, das heißt, die genaue räumliche Anordnung der Atome festzustellen. Seit kurzer Zeit ist es möglich, solche Strahlung auch in Form von extrem kurzen Blitzen herzustellen. Diese Blitze sind so kurz, dass die extrem schnelle Bewegung der Atome, die in der Materie stattfindet, eingefroren erscheint. Mit einer Folge solcher Schnappschüsse wird es in Zukunft gelingen, Filmaufnahmen vom Ablauf atomarer Vorgänge herzustellen.
description: Changes in the atomic configuration underlying chemical reactions, phase transitions or many other fundamental processes in nature take place on a femtosecond (fs) time scale; that is, roughly speaking 10-14 to 10-13 s (1 fs = 10-15s). Although they provide the necessary time resolution, ultrafast lasers and optical spectroscopy lack the spatial resolution that would be required to directly track the motion of the atoms. Recently, ultrashort X-ray pulses with subnanometer wavelength have been developed, enabling a combination of femtosecond time resolution and atomic spatial resolution. Thus the vision of scientists being able to take snapshots of rapidly changing, complex atomic structures appears to be within reach.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 32Naturwissenschaften - Physik: Energieumwandlungen an Oberflächen, p. 42
title: Wege zur Formelsprache: Entwicklung algebraischen Denkens als didaktische Aufgabe
Creators: name: Hefendehl-Hebeker, Lisa
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 510

description: In diesem Beitrag geht es um eine möglichst sinnerfüllte, nicht abschreckende Einführung der algebraischen Formelsprache im Mathematikunterricht und die damit verbundene didaktische Herausforderung.
description: The development of symbolic algebra in early modern times was a constitutive innovation for mathematics and its applications and was without precedent up until that point. The introduction of symbolic language into reasonable use is still a challenge for mathematics education.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 66
The effects of forest gap size on Douglas-fir seedling establishment in the southern interior of British Columbia
Creators: name: Zustovic, Matt
Publisher: name: The University of British Columbia
Year: 2012

description: This study focuses on seedling germination and survival of Douglas-fir (Pseudotsuga mensiezii var. glauca [Beissn.] Franco) seedlings in an Interior Douglas-fir (IDF) biogeoclimatic zone forest. Plots were established in the centers of naturally occurring forest gaps of varying sizes (large, medium, and small) and Douglas-fir seedlings were planted with or without the ability to associate with ectomycorrhizal (EM) networks. As seedlings cannot make EM associations until one or sometimes two seasons of after germination, this paper does not report data on EM effects, but refers to literature on the influence of EM networks. A three factorial design was used to assess the effect of gap size and mycorrhizal influence with 9 replications on seedling germination and survival. Data was collected on 3 separate days during the 2011 growing season and included germination counts as well as volumetric soil moisture content data using a ML2 theta probe®. Results for germination were not normally distributed therefore rejecting parametric statistics; however, it was detected that large gaps had lower seedling survivability even though results are not significant. Moisture content data showed that soil moisture could have played a role in tree survivorship but more data is necessary.
title: Zeitaufgelöste Elektronenbeugung: ein Film über ultraschnelle, atomare Prozesse
Creators: name: Krenzer, Boris
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 530

description: Der Beitrag stellt mit der zeitaufgelösten Elektronenbeugung eine neue Methode vor, die es erlaubt, die Bewegung von Atomen auf Oberflächen beziehungsweise von Atomen einer Oberfläche selbst sichtbar zu machen. Mit Hilfe dieser neuen Methode sollen fundamentale Fragen zu Prozessen beantwortet werden, die stattfinden, wenn eine Oberfläche mit einem Laser beschossen wird.
description: The dynamics of atoms following laser excitation is an area of special interest that has not been addressed in great detail in the past. It will yield insight into microscopic processes of the light-matter-interaction. Studies regarding direct atomic movement contribute to the understanding of the total energy transfer chain, starting with the initial laser excitation, which ultimately results in the generation of heat at the surface and in the bulk of a crystal. In recent years, a time-resolved electron diffraction (TRED) experiment has been set up at the University of Duisburg-Essen. In this pump and probe experiment a laser pulse excites a surface. The structural dynamics are probed using short electron pulses generated by photoemission. The heating and cooling of a thin Bismuth film deposited on a Silicon substrate has been investigated in an initial experiment. The heating of the thin film could not be studied in detail because the temporal resolution is not yet sufficient. The cooling, however, occurs on a much longer timescale. It was observed that the cooling rate of the thin film is dramatically reduced compared to a Bismuth single crystal. This is explained by the boundary between Bismuth and Silicon acting as a barrier to heat transport. The observed cooling rate is in good agreement with models describing the thermal boundary conductance.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 32Naturwissenschaften - Physik: Energieumwandlungen an Oberflächen, p. 56
title: Der Zusammenhang von Modulformen und Zahlkörpern: Zahlentheorie und Geometrie vereint in der Serre-Vermutung
Creators: name: Wiese, Gabor
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 510

description: Der Beweis der Serre-Vermutung, die einen Zusammenhang zwischen Zahlentheorie und Geometrie herstellt, ist erst vor kurzem gelungen. Gabor Wiese gibt einen Überblick über diese Vermutung, die für die Forschung am Institut für Experimentelle Mathematik eine nicht unerhebliche Bedeutung hat.
description: Recently one of the most important structural conjectures in pure mathematics, Serre’s modularity conjecture, has become a theorem, proved mainly by Khare and Wintenberger. Serre’s conjecture establishes a link between seemingly different areas: number theory and geometry. This link is made through modular forms, which are functions dating back to the 19th century. The main aim of the article is to describe the content of Serre’s conjecture in a non-technical language. Moreover, links to past and ongoing research in Essen are mentioned, as well as some consequences of Serre’s conjecture. The article first surveys the objects involved in Serre’s conjecture: modular forms and Galois representations. According to a theorem by Deligne and Shimura, any Hecke eigenform gives an odd 2-dimensional Galois representation. This is illustrated by means of a simple example. Serre’s conjecture postulates that the converse is also true: any odd 2-dimensional irreducible Galois representation comes from a Hecke eigenform. The remainder of the article is devoted to explaining these objects in more detail. Different types of ’numbers’ and ’fields’ are introduced, discussed and compared: algebraic numbers, real numbers, complex numbers, number fields and finite fields. Subsequently, complex geometry, in particular Riemann surfaces, are touched upon, and geometry over number fields (arithmetic geometry) is mentioned. The article emphasizes the role played by symmetries. It takes the point of view that modular forms link geometry and number theory via symmetries: Möbius transforms, Hecke operators and Galois and Frobenius automorphisms are united as different kinds of symmetries. These objects are explained. Modular forms are presented as objects coming from and being rooted in geometry. The link between modular forms and Galois representations provided by Serre’s modularity conjecture is finally explained in more detail and one small glimpse on its proof is provided. A final section puts Serre’s conjecture into the context of Langlands’ philosophy.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 72
title: Schnell, schwer, hoch geladen: Ionen als Werkzeuge für die Festkörperphysik
Creators: name: Schleberger, Marika
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 530

description: Ionen eignen sich aufgrund ihrer Eigenschaften hervorragend für die Festkörperphysik: Die Art der Energieabgabe von Ionen in Materie hängt von ihrer Bewegungsenergie ab. Schnelle, energiereiche Ionen werden hauptsächlich durch die Wechselwirkung mit den Elektronen des Materials abgebremst (electronic stopping). Langsame, energiearme Ionen verlieren ihre Energie hauptsächlich durch Stöße mit den Atomkernen des Materials (nuclear stopping).
description: Ions are a very versatile tool in solid-state physics. Depending on their energy and their charge state, different interactions with solid matter can be studied. In the case of swift heavy ions, the ion/solid interaction is governed by so-called electronic stopping. The energy loss of the projectile is mainly due to electronic excitations that arise in the wake of the ion travelling through the solid. The response of the solid depends on its electronic structure. In the case of a metal, the excitation dissipates before the lattice can be heated. Since the electronic system quickly relaxes into its original state, usually no evidence of the passing ion is found. In the case of an insulator, the coupling of electronic excitations to acoustic and optic modes of the lattice is very strong. As a consequence, the electronic excitation is transferred rather efficiently to the lattice and melting occurs. This very intense, rapid and localized excitation is called a thermal spike. The spike usually leaves the lattice heavily disturbed. The static legacy of this highly dynamic process can be imaged through scanning force microscopy. Each ion produces a nanometer-sized hillock on the surface. In this way, nanoscale modifications of technologically interesting materials become feasible. If the surface is tilted with respect to the beam, chains of hillocks appear. Because the crystal is anisotropic with respect to the electron density, the ion can lose energy only when it passes a layer with a high enough electron density. Another important aspect is the charge state of the ion. Even with slow, highly charged ions; i.e. in the regime of nuclear stopping, an electronic excitation due to the many missing electrons can be injected into the solid. Future experiments will shed light on the corresponding energy dissipation processes.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 32Naturwissenschaften - Physik: Energieumwandlungen an Oberflächen, p. 70
title: Optimierung unter Ungewissheit: „... das eigentliche Problem“
Creators: name: Schultz, Rüdiger
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 510

description: Die adäquate Einbindung von Ungewissheit ist eine immer drängendere Notwendigkeit bei der Lösung von Optimierungsproblemen aus der Praxis. Die stochastische Optimierung bietet dazu ein reichhaltiges Methodenspektrum, zu dessen weiterer Ausgestaltung es des Zusammenwirkens unterschiedlicher mathematischer Teildisziplinen bedarf.
description: With closer inspection, almost any practical optimization problem is affected by uncertainty. Growing interconnection of economic activity and liberalization of markets for energy and raw materials are striking examples for the increasing role of uncertainty in practical optimization. Stochastic programming offers a wide spectrum of mathematical models for coping with uncertainty. Structural analysis of these models and, on top of that, the design of practicable solution procedures are in the core of current research and often require completely new mathematical approaches. This leads to a fruitful interplay of fairly different mathematical disciplines such as analysis, discrete mathematics, and probability theory. This way, algorithms and software have emerged in recent years, which enable the successful solution of stochastic programs from practice whose complexity is ever growing.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 84
title: Billard mit Atomen: kinetisch induzierte Energietransferprozesse an Oberflächen
Creators: name: Wucher, Andreas
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 530

description: Trifft ein Atom oder Ion auf eine Festkörperoberfläche, so löst es unter den Oberflächenatomen eine Kaskade schneller, zumeist elastischer Stöße aus, die denjenigen der Billardkugeln beim Billardspiel sehr ähnlich sind. Diesen als „Festkörperzerstäubung“ oder auch „Sputtering“ bezeichneten Prozess kann man technologisch ausnutzen. Heute werden viele der wahrgenommenen Eigenschaften von Werkstücken im Wesentlichen durch Oberflächen mit sehr dünnenBeschichtungen bestimmt, die durch Sputtering hergestellt und auch charakterisiert werden können. Zum Beispiel werden Werkzeuge wie Bohrer, Fräser etc. mit superharten, diamantartigen Schichten gegen Verschleiß geschützt.
description: The interaction of ion beams with solid surfaces is of great technological importance. One of the fundamental open questions in this area regards the dissipation channels of projectile energy (either kinetic or potential), which is introduced into the surface. In the frame of the SFB 616, we investigate particularly the electronic excitation following from an ion impact onto a metallic surface. Sputtering, i. e., the release of surface particles by means of billiard-like atomic collision cascades initiated by the projectile impact, forms the physical basis for deposition and lateral structuring methods of thin films. Moreover, mass spectrometry of sputtered particles constitutes a well-established technique for high resolution chemical surface analysis. The big advantage with respect to other surface analysis tools is that the mass spectra yield information about the molecular structure of the investigated surface. Combined with ion-induced erosion, this enables a three-dimensional chemical analysis of complex surface structures. In this field, the recently established availability of cluster ion sources has opened up new possibilities with respect to applications of this technique to soft matter.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 32Naturwissenschaften - Physik: Energieumwandlungen an Oberflächen, p. 80
title: Aus Liebe zum Detail: Funktionskeramiken unter dem numerischen Mikroskop
Creators: name: Schröder, Jörg
name: Keip, Marc-André
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 620

description: Elektromechanische Funktionskeramiken sind Bestandteil vieler hochmoderner industrieller Anwendungen. Ihre Einsatzmöglichkeiten umspannen die klassischen Ingenieurwissenschaften wie die der Automobiltechnik, in der sie als integraler Teil von Einspritzdüsen kraftstoffsparender Motoren Anwendung finden, genauso wie die der Informationstechnologie, der Elektronik und Sensorik. Neuere Entwicklungen in der Medizintechnologie kündigen auch hier einen vielversprechenden Einsatz an, beispielsweise als elementarer Bestandteil filigraner Hörgeräte. Auch als nichtflüchtige elektronische Speicher „Ferroelectric Random Access Memory“ kommen diese Materialien zum Einsatz. Um das komplexe Materialverhalten dieser Stoffe elektromechanisch zu beschreiben, bedarf es einer erschöpfenden kontinuumsmechanischen Herangehensweise. So forciert der spezielle kristallographische Aufbau der Keramiken eine mikromechanisch motivierte Formulierung der elektromechanischen Feldgleichungen und zudem eine Berücksichtigung der wesentlichen mikromechanischen Effekte, denen im Zuge der Simulation mit einer Mehrskalenformulierung Rechnung getragen wird.
description: Smart materials, like piezo- and ferroelectric materials, are of high interest for modern engineering solutions in both industry and science. They build an important class of technical devices being part of engineering applications like fuelefficient motors and many other hightech solutions. Their functionality and reliability make them a key product for sound future developments. However, as every technical device smart materials need a physical and mathematical understanding of the underlying physical processes. For the description of those processes the engineer makes use of differential equations which are able to describe the physical behaviour in a mathematical way. For piezoand ferroelectrics the fundamental differential equations are the balance of momentum and the Gauß law. To complete the mathematical model, physical information has to be integrated which is achieved by use of thermodynamic considerations. These yield corresponding material laws that are able to describe the physical processes within the material. In general, phenomenological material models are used to model the physical behaviour of a material. Since such phenomenological models are describing the physical material behaviour only to a certain extent, sometimes a more general approach is necessary. In such cases micromechanical models can be applicated to reflect the real material response. This is done by using a homogenisation ansatz on the basis of a multiscale approach. In this context the real microscopic material structure is discretized and integrated into the macroscopic model through homogenisation.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 94
Identifying western spruce budworm defoliation events in the IDF zone using dendroentomology
Creators: name: Fegyverneki, James
Publisher: name: The University of British Columbia
Year: 2012

description: A dendroentomological analysis has been conducted for one site in the Interior Douglas-fir biogeoclimatic zone in near Clinton, British Columbia, Canada. This is a pilot study of work that is to be part of a synthesis of data collected from 30 throughout the southern interior forests of British Columbia. The study aims to reconstruct defoliation events caused by western spruce budworm (Choristoneura occidentalis Freeman) on the host species Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Defoliation from western spruce budworm causes a reduction in tree radial growth and can be visually identified in the tree rings. This paper discusses western spruce budworm biology, history in British Columbia, and implications that climate change may have on the future ecologic integrity of the study area and on future outbreaks. As a test of analytical methods, western spruce budworm defoliation history was studied by identifying periods of reduced growth using cores taken from 20 Douglas-fir trees from one site in an area of known defoliation near Clinton, British Columbia. Dendrochronological software CooRecorder and CDendro were used to measure tree ring widths and crossdate the data, respectively. The Douglas-fir host chronology was compared to a non-host ponderosa pine (Pinus ponderosa Douglas ex C. Lawson) chronology to account for any climatic variations that may also cause growth reductions. This study resulted in the identification of eight distinct suppression events from 1685 to 1965 that were likely caused by the western spruce budworm in the Clinton region.
title: Chemische Reaktionen lassen Elektronen nicht kalt: über die verschlungenen Wege der Reaktionswärme an Metalloberflächen
Creators: name: Diesing, Detlef
name: Nienhaus, Hermann
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 530

description: Die Chemoelektronik spannt eine Brücke ziwschen den Welten der elektronischen Bauelemente und der Oberflächenchemie. Mit ihrer Hilfe lassen sich alte Fragen neu beantworten. Eine davon handelt von dem Rätsel, wie die freiwerdende Energie bei chemischen Reaktionen an Oberflächen auf den Festkörper übertragen wird.
description: Chemical reactions on surfaces play an important role in the fields of catalysis, chemistry, gas sensing and gas catalytic conversion. They release energy, which – in the long run – leads to heat. However, little is know about the mechanisms of energy transfer into the surface. Heretofore, the direct conversion of chemical energy into heat (phonons) has been considered the dominant path of energy transfer. Today, the use of new experimental methods including thin-film electronic devices, has revealed an alternative way of energy transfer: electrons in the surface are excited by the reaction, which then relax and heat up the surface. The authors of the article describe the design and application of two different devices, Schottkydiodes and metal-insulator-metal contacts, to detect the chemically induced hot electrons. Similar to solar cells, which produce electric currents when they are illuminated, the chemoelectric devices give currents when they are exposed to reactive gases. This effect may be used to study the kinetics of the reactions and to develop new kinds of gas sensors.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 32Naturwissenschaften - Physik: Energieumwandlungen an Oberflächen, p. 90
title: Einsteins Erbe: Mathematische Einblicke in schwarze Löcher
Creators: name: Kunze, Markus
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 510

description: Dieser Übersichtsartikel gibt Auskunft über schwarze Löcher in der Allgemeinen Relativitätstheorie und diskutiert ihre Eigenschaften aus mathematischer Sicht. Zu den behandelten Themen gehören Eindeutigkeitssätze für schwarze Löcher, quantenmechanische Effekte, die Thermodynamik schwarzer Löcher, kosmische Zensur, der Gravitationskollaps sowie die Existenz und Stabilität von Lösungen der relevanten Gleichungen.
description: This short overview paper concerns the properties of black holes and the general theory of relativity, mainly taking a mathematical viewpoint. Among other topics we briefly discuss uniqueness theorems for black holes, quantum effects, black hole thermodynamics, cosmic censorship, gravitational collapse, and the existence and stability of solutions in general.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 108
title: “There are lies, damned lies, and statistics”: Wahrscheinlichkeit und Statistik
Creators: name: Davies, Laurie
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2008
Subjects: subject: 510

description: Laurie Davies erläutert in seinem Artikel einige Fragestellungen der Wahrscheinlichkeitstheorie und beleuchtet sie als Teil der Mathematik, der auch auf komplexe Systeme und Zustände anwendbar ist.
description: The article discusses some of the problems concerning the interpretation of the concept of probability. It is emphasized that the mathematical theory of probability, being a part of mathematics, is not affected by such considerations, but that there are problems with subjective and frequentist interpretations when it comes to applications. In particular the frequentist requirement that the experimental conditions remain the same for all repetitions is in conflict with deterministic theories of nature. A deterministic nature does not per se imply the inapplicability of probability theory. It can be shown mathematically that complex sequences of numbers and certain deterministic chaotic systems behave like random systems and can be well described using probability theory. Statistics is one form of applied probability theory and is consequently more influenced by problems of interpretability than is probability theory itself. In its pure form Bayesian statistics is concerned with degrees of belief and how these should be altered in the light of experimental evidence. Frequentist statistics is more concerned with providing procedures which are optimal for repeated applications under similar circumstances. In practice both pure forms are tempered by practical necessities. The article describes two special areas of statistics, robust statistics and nonparametric regression. Robust statistics is concerned with the detection and accommodation of outlying or aberrant observations as they occur for example in interlaboratory tests and the analysis of variance. Non-parametric regression is concerned with estimating a functional relationship between two variables when this is contaminated by noise. The example discussed comes from the area of thin film physics where the intensity of diffracted x-rays depends on the angle of diffraction.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 33Mathematik: eine lebendige Wissenschaft, p. 118
Supplementary document for Label-free neural networks-based inverse lithography technology - 6137158.pdf
Creators: name: chen, jing
name: Zhao, Yuan-Yuan
name: Zhang, Yang
name: Zhu, Jianxin
name: duan, xuan-ming
Publisher: name: Optica Publishing Group
Year: 2025
Subjects: Classical and Physical Optics

description: Supplemental Document
title: Editorial
Creators: name: Bingmann, Dieter
name: Lutterbach, Hubertus
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2009
Subjects: subject: 230
subject: 610

description: UNIKATE: Berichte aus Forschung und Lehre, no. 35Natur-/Geisteswissenschaften: Sterben, Tod – und dann?, p. 6
title: Altern und Sterblichkeit: Eine Perspektive der Genetik und Evolution
Creators: name: Passarge, Eberhard
name: Horsthemke, Bernhard
Publisher: name: DuEPublico: Duisburg-Essen Publications online, University of Duisburg-Essen, Germany
Year: 2009
Subjects: subject: 610

description: Altern und Tod sind evolutionär notwendige Begleiterscheinungen aller vielzelligen Lebewesen. Individueller Tod ist Voraussetzung für das Überleben einer Spezies. Nur wenn individuelle Mitglieder einer Spezies sterben, kann eine neue Generation mit neuen Kombinationen von Genen entstehen. Auf zellulärer Ebene ist der programmierte Zelltod in bestimmten Geweben und zu den richtigen Zeiten eine Voraussetzung für erfolgreiche embryonale Entwicklung. Alle Lebewesen haben eine artenspezifische Lebensspanne, die eng mit dem Alterungsprozess verknüpft ist.
description: Ageing and death are necessary evolutionary components in the life of multicellular organisms. The survival of a species requires death of its individuals at a given time. Only on this basis can a new generation arise with a new combination of genes. At the cellular level, programmed cell death (apoptosis) in different tissues and at the right time is required for normal embryonic development. All living organisms have a species-specific lifespan. This is closely related to the process of ageing. All genes required to reach and complete the reproductive phase of an organism are subject to natural selection. In contrast, selective pressure is alleviated for genes that are required later on, after the reproductive phase has been completed. The rate of ageing appears to be influenced by genetic factors. In particular, different types of stem cells play an important role. Under the influence of specialized genes, stem cells retain the ability to remain undifferentiated and continue to divide without signs of ageing until the death of the individual.
description: UNIKATE: Berichte aus Forschung und Lehre, no. 35Natur-/Geisteswissenschaften: Sterben, Tod – und dann?, p. 8
Projektni zadaci za TOBS predmet
Creators: name: Miljković, Nadica
Publisher: name: Zenodo
Year: 2023
Subjects: analiza signala
statistička analiza
eksplorativna analiza
izdvajanje obeležja
mašinsko učenje
vizuelizacija
geoprostorno mapiranje

description: Spisak projektnih zadataka za predmet Tehnike obrade biomedicinskih signala na Elektrotehničkom fakultetu Univerziteta u Beogradu u školskoj 2022/23. godini. Neki od projekata su preuzeti od ranijih godina.