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Search Results: 1 - 10 of 101 matches for " Klar "
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Formation of Slow Electron Pairs in an External Coulomb Field  [PDF]
Hubert Klar
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.87065
Abstract: The wave equation for two electrons in an external Coulomb field (helium-like atoms) has been shown to be a problem in a three-dimensional half-space. The wave-equation becomes quasi-separable in inertial coordinates. This allows to work out the electron motion in the frame of principal inertia axes. We find that non-adiabatic coupling terms constitute a fictitious force and lead to a deformation of the static potential surface. Incoming and outgoing modes of electron pairs are studied in detail, and applied to the threshold ionization of hydrogen-like atoms by electrons. Our analysis confirms the classical work by Wannier. However, we go beyond Wannier and present bending and stretch vibrations of electron pairs. The bending vibration has no influence onto the total ionization cross-section. The pair formation below threshold destroys the existence of high double Rydberg resonances. Finally, we describe the propagation of an electron pair through a linear chain of Rydberg atoms.
Correlation-Induced Electron-Electron Attraction  [PDF]
Hubert Klar
Journal of Modern Physics (JMP) , 2018, DOI: 10.4236/jmp.2018.99110
Abstract: The multidimensional potential surface of a few (2 - 4)-electron atom shows near equilibrium configurations ridge structures. The electron wave diffraction from such a ridge is shown to induce a novel fictitious force which manifests itself as temporary electron-electron attraction. In contrast to a Cooper pair our pair does not need a lattice vibration and may be regarded as elementary prototype pair in an isolated atom. Also electron triples and quadruples are discussed.
Buchbesprechung: Was hei t und zu welchem Ende betreibt man medizinische Dokumentation?
Klar, Rüdiger
GMS Medizinische Informatik, Biometrie und Epidemiologie , 2007,
Abstract:
10Gb/s Bang-Bang Clock and Data Recovery (CDR) for optical transmission systems
N. Dodel,H. Klar
Advances in Radio Science : Kleinheubacher Berichte , 2005,
Abstract: A Bang-Bang Clock-Data Recovery (CDR) for 10Gb/s optical transmission systems is presented. A direct modulated architecture is used for the design. Its loop characteristics can be derived using an analogy to Σ Δ theory. The circuit was produced and measured in a commercial 0.25μm BiCMOS technology with a transition frequency fT70=GHz.
Bone Induction: Regeneration through Chaos
Roland Manfred Klar
Frontiers in Physiology , 2011, DOI: 10.3389/fphys.2011.00021
Abstract:
Flooding in urban drainage systems: Coupling hyperbolic conservation laws for sewer systems and surface flow
Raul Borsche,Axel Klar
Physics , 2014, DOI: 10.1002/fld.3957
Abstract: In this paper we propose a model for a sewer network coupled to surface flow and investigate it numerically. In particular, we present a new model for the manholes in storm sewer systems. It is derived using the balance of the total energy in the complete network. The resulting system of equations contains, aside from hyperbolic conservation laws for the sewer network and algebraic relations for the coupling conditions, a system of ODEs governing the flow in the manholes. The manholes provide natural points for the interaction of the sewer system and the run off on the urban surface modelled by shallow water equations. Finally, a numerical method for the coupled system is presented. In several numerical tests we study the influence of the manhole model on the sewer system and the coupling with 2D surface flow.
Expectile Asymptotics
Hajo Holzmann,Bernhard Klar
Statistics , 2015,
Abstract: We discuss in detail the asymptotic distribution of sample expectiles. First, we show uniform consistency under the assumption of a finite mean. In case of a finite second moment, we show that for expectiles other then the mean, only the additional assumption of continuity of the distribution function at the expectile implies asymptotic normality, otherwise, the limit is non-normal. For a continuous distribution function we show the uniform central limit theorem for the expectile process. If, in contrast, the distribution is heavy-tailed, and contained in the domain of attraction of a stable law with $1 < \alpha < 2$, then we show that the expectile is also asymptotically stable distributed. Our findings are illustrated in a simulation section.
Simulating Spiraling Bubble Movement in the EL Approach  [PDF]
Andreas Weber, Hans-J?rg Bart, Axel Klar
Open Journal of Fluid Dynamics (OJFD) , 2017, DOI: 10.4236/ojfd.2017.73019
Abstract: Simulating the detailed movement of a rising bubble can be challenging, especially when it comes to bubble path instabilities. A solution based on the Euler Lagrange (EL) approach is presented, where the bubbles show oscillating shape and/or instable paths while computational cost are at a far lower level than in DNS. The model calculates direction, shape and rotation of the bubbles. A lateral force based on rotation and direction is modeled to finally create typical instable path lines. This is embedded in an EL simulation, which can resolve bubble size distribution, mass transfer and chemical reactions. A parameter study was used to choose appropriate model constants for a mean bubble size of 3 mm. To ensure realistic solution, validation against experimental data of single rising bubbles and bubble swarms are presented. References with 2D and also 3D analysis are taken into account to compare simulative data in terms of typical geometrical parameters and average field values.
Digitalsimulator für pulscodierte neuronale Netze
H. H. Hellmich,H. Klar
Advances in Radio Science : Kleinheubacher Berichte , 2005,
Abstract: Die Simulation von grossen pulscodierten neuronalen Netzen (PCNNs) für die Evaluierung einer biologisch motivierten Bildverarbeitung ist auf Einprozessor-Systemen (PCs oder Workstations) immer noch sehr zeitineffizient. Den Flaschenhals w hrend der Simulation bildet der sequentielle Zugriff auf den Gewichtsspeicher zur Berechnung der Neuronenzust nde. Es wird ein Digitalsimulator basierend auf feld-programmierbaren Gate-Arrays (FPGAs) vorgestellt, der dieses Flaschenhals-Problem durch eine verteilte Speicherarchitektur und eine erh hte Speicherbandbreite angeht und zus tzlich eine getrennte Berechnung von Neuronenzust nden und Netzwerktopologie vorsieht. Somit ist es m glich, den des Simulationsalgorithmus zu erh hen. Die momentane Implementierung mit einer Taktfrequenz von 50MHz verspricht einen Beschleunigungsfaktor von etwa 30 für eine sp rliche Vernetzungsstruktur (Vierer- und Achternachbarschaft) im Vergleich zu einem PC mit einer 2,4GHz CPU und 1GB RAM Arbeitsspeicher.
Nonexistence of steady solutions for rotational slender fibre spinning with surface tension
Thomas G?tz,Axel Klar
Mathematics , 2015,
Abstract: Reduced one-dimensional equations for the stationary, isothermal rotational spinning process of slender fibers are considered for the case of large Reynolds ($\delta=3/\text{Re}\ll 1$) and small Rossby numbers ($\varepsilon \ll 1$). Surface tension is included in the model using the parameter $\kappa=\sqrt{\pi}/(2 \text{We})$ related to the inverse Weber number. The inviscid case $\delta=0$ is discussed as a reference case. For the viscous case $\delta > 0$ numerical simulations indicate, that for a certain parameter range, no physically relevant solution may exist. Transferring properties of the inviscid limit to the viscous case, analytical bounds for the initial viscous stress of the fiber are obtained. A good agreement with the numerical results is found. These bounds give strong evidence, that for $\delta > 3\varepsilon^2 \left( 1- \frac{3}{2}\kappa +\frac{1}{2}\kappa^2\right)$ no physical relevant stationary solution can exist.
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