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Paderborn, Germany

The University of Paderborn in Paderborn, North Rhine-Westphalia, Germany was founded in 1972. 17,421 students were enrolled at the university as of December 2011.It offers students 105 different degree programmes. The University of Paderborn ranks high in the areas of Computer Science, Business Management and English. The university’s library also has an excellent reputation. Because of its large selection of electronic media, and its long opening hours and lending periods, it is said to be one of the best university libraries in Germany. The number of students enrolled at the university has steadily increased in recent years, and as a result, the university has begun expanding the main building. Although the campus is not centrally located, you can reach the university within minutes using public transportation.Particularly notable is the newly established Master of Arts program in Comparative Literature in the faculty of Cultural Studies.In 2006 the computer science program has been ranked among the top 3 programs in the most comprehensive and detailed ranking of German universities by the Centre for Higher Education Development and the German weekly news magazine "Die Zeit". Also in 2006 the university has been ranked among the leading institutions for gaining research funding in the areas of electrical engineering, computer science and systems engineering by the German Research Council .RailCab is a research project by the University of Paderborn. Its purpose is the examination of the use of linear engines for the propulsion of autonomous, rail mounted vehicles. Wikipedia.

Winkler M.,University of Paderborn
Archive for Rational Mechanics and Analysis | Year: 2014

This paper deals with an initial-boundary value problem for the system (Formula Presented.) which has been proposed as a model for the spatio-temporal evolution of populations of swimming aerobic bacteria. It is known that in bounded convex domains Ω ⊂ ℝ2 and under appropriate assumptions on the parameter functions χ, f and φ{symbol}, for each κ ∈ ℝ and all sufficiently smooth initial data this problem possesses a unique global-in-time classical solution. The present work asserts that this solution stabilizes to the spatially uniform equilibrium (n̄0, 0, 0), where n̄0:=1/{pipe}Ω{pipe} ∫Ωn(x, 0)dx, in the sense that as t→∞, (Formula Presented.) hold with respect to the norm in L∞(Ω). © 2013 Springer-Verlag Berlin Heidelberg. Source

Winkler M.,University of Paderborn
Journal of Nonlinear Science | Year: 2014

We consider nonnegative solutions of the Neumann initial-boundary value problem for the chemotaxis-growth system (Formula presented) along with the corresponding limit problem formally obtained upon taking. For the latter hyperbolic–elliptic problem, we establish results on local existence and uniqueness within an appropriate generalized solution concept. In this context we shall moreover derive an extensibility criterion involving the norm of. This will enable us to conclude that in this caseif (Formula presented.), then all solutions emanating from sufficiently regular initial data are global in time, whereas if (Formula presented.), then some solutions blow-up in finite time. though known to possess no such exploding solutions, exhibits the following property of dynamical structure generation: given any , one can find smooth bounded initial data with the property that for each prescribed number will attain values above is sufficiently small. In particular, this means that the associated carrying capacity given by can be exceeded during evolution to an arbitrary extent. We finally present some numerical simulations that illustrate this type of solution behavior and that, moreover, inter alia, indicate that achieving large population densities is a transient dynamical phenomenon occurring on intermediate time scales only. © 2014, Springer Science+Business Media New York. Source

Bauer M.,University of Paderborn
Physical Chemistry Chemical Physics | Year: 2014

In this perspective, the HERFD-XANES (high energy resolution fluorescence detected X-ray absorption near edge structure) and Kβ2,5- or V2C-XES (valence-to-core X-ray emission spectroscopy) methods are discussed as new and powerful tools for chemical research with hard X-rays. This includes a brief survey of the underlying physical processes and the introduction of experimental issues. The potential of both methods to overcome limitations of conventional XAS (X-ray absorption spectroscopy) and to push the limits for obtaining new information about the electronic and geometric structures of metal centers, in the solid state structure or heterogeneous catalysts, but also in metal complexes and homogeneous catalysts, is discussed by presenting a survey of representative references and recent own studies, rounded off by a conclusion and outlook. This journal is © the Partner Organisations 2014. Source

Hussain H.,University of Paderborn | Hussain H.,The University of Nizwa | Green I.R.,Stellenbosch University | Ahmed I.,Karlsruhe Institute of Technology
Chemical Reviews | Year: 2013

The various synthetic methods discussed in this review reveal that Oxone is a versatile reagent used in organic synthesis. Oxone is a cheap commercially available oxidant that easily oxidizes numerous functional groups. It is an efficient single oxygen-atom donor since it contains a nonsymmetrical O-O bond which is heterolytically cleaved during the oxidation cycle. It is an inexpensive reagent ($0.02-0.04/g), which compares favorably with hydrogen peroxide and bleach. Its byproducts do not pose an immediate threat to aquatic life upon disposal, and unlike chromium trioxide and bleach, it does not emit pungent vapors or pose a serious inhalation risk. The aqueous components of an organic Oxone reaction are oxidizing and acidic and should thus be quenched with sodium bisulfite followed by neutralization with sodium bicarbonate, thereby resulting in formation of a mixture of nonhazardous sulfate salts in water. These features make Oxone attractive for large-scale applications. Uses of other oxidizing agents lack the desired ingredients to attract the interest of industry because of tedious purification processes from their deoxygenated counterparts. The dioxirane (generated from reaction between Oxone and a ketone) epoxidation offers many advantages over traditional methods of epoxidation. Oxone is about one-half as expensive as m-chloroperoxybenzoic acid (mCPBA) and converted to KHSO4. KHSO4 during the reaction, while being relatively acidic, can easily be neutralized with dilute NaOH solution to produce nontoxic Na2SO4. Furthermore, the reaction conditions require the use of relatively nontoxic organic solvents plus water. Another advantage of dioxirane epoxidation is that acetone is recycled in the reaction, which means all of the extra oxygen in Oxone is incorporated into the respective alkenes. Dioxirane is also capable of oxidizing very unreactive olefins, and thus, isolation of some relatively unstable epoxides produced from glycals is possible. This represents a major advantage over the Sharpless and mCPBA protocols, which only epoxidize electron-rich olefins and allylic or homoallylic alcohols. These latter reagents also require a directing group. One drawback that dioxirane does have is the fact that it can also oxidize very reactive heteroatoms, hydroxyl groups, and unactivated C-H bonds during the epoxidation procedure. Oxone does have some disadvantages: (a) it is insoluble in organic solvents, (b) buffering is needed due to its acidity, and (c) it sometimes bleaches the metal catalysts and donor ligands during oxidation reactions. To overcome the need for aqueous conditions, some authors have used ionic liquids as solvent, and additionally, several tetraalkylammonium salts of Oxone have been reported. It has been found that when the cation in Oxone (i.e., K+) is changed to, e.g., n-Bu4N+, the oxidant also shows higher solubility in organic solvents, especially in dichloromethane. Tactical utilization of Oxone in synthetic plans is that it may replace tedious organic transformations with simpler routes. One other drawback which needs to be mentioned is that a relatively large excess of Oxone may be required in some reactions to consume all of the starting material. However, militating against this is that Oxone can be reused when it is in stoichiometric excess. Owing to the discovery of a variety of novel applications, Oxone is becoming an increasingly important reagent in synthetic organic chemistry. We hope that this review may act as a catalyst in boosting applications of Oxone in organic synthesis. Source

Mahnken R.,University of Paderborn
International Journal of Solids and Structures | Year: 2013

We develop a macroscopic constitutive model for temperature-dependent visco-elastic effects accompanied by curing, which are important phenomena in production processes. Within a thermodynamic framework we use an additive ternary decomposition of the logarithmic Hencky strain tensor into mechanical, thermal and chemical parts. Based on the concept of stoichiometric mass fractions for resin, curing agent and solidified material the bulk compression modulus as well as the bulk heat- and shrinking dilatation coefficients are derived and compared with ad hoc assumptions from the literature. Moreover, we use the amount of heat generated during differential scanning calorimetry until completion of the chemical reactions, to define the chemical energy. As a major result, the resulting latent heat of curing occurring in the heat-conduction equation derived in our approach reveals an ad hoc approach from the literature as a special case. In addition, thermodynamic consistency of the model will be proved, and the numerical implementation of the constitutive equations into a finite-element program is described. In the examples we illustrate the characteristic behaviour of the model, such as shrinking due to curing and temperature dependence and simulate the deep drawing of a spherical part with the finite-element-method. © 2013 Elsevier Ltd. All rights reserved. Source

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