Search results for "Names"

Über eine eichung eines 7.5 × 7.5 cm - NaJ(Tl) - Vollkristalls zur absolutzählung flächenförmiger präparate

1966

Abstract The photopeak efficiency and the peak-to-total ratio for a 7.5 × 7.5 cm solid NaI(Tl)-crystal are determined in the range of 0.145–1.33 MeV. The disintegration rates of the disc sources used are known by 4 πβ -and 4 πβ - γ -coincidence measurements. The effect of the disc diameter and the distance source-crystal on the photopeak efficiency is studied thoroughly. The data obtained are compared with those of other authors. The evaluation of the photopeak area is performed in a frequency diagram, a special type of probability scale, in which both parts of the Gaussian curve are represented by straight lines. Hence, corrections for the Compton overlap, bremsstrahlung and background can…

Models for highway traffic and their connections to thermodynamics

2007

Models for highway traffic are studied by numerical simulations. Of special interest is the spontaneous formation of traffic jams. In a thermodynamic system the traffic jam would correspond to the dense phase (liquid) and the free flowing traffic would correspond to the gas phase. Both phases depending on the density of cars can be present at the same time. A model for a single lane circular road has been studied. The model is called the optimal velocity model (OVM) and was developed by Bando, Sugiyama, et al. We propose here a reformulation of the OVM into a description in terms of potential energy functions forming a kind of Hamiltonian for the system. This will however not be a globally …

A scalar Volterra derivative for the PoU-integral

2005

2012

We study the Wigner function for a quantum system with a discrete, infinite dimensional Hilbert space, such as a spinless particle moving on a one dimensional infinite lattice. We discuss the peculiarities of this scenario and of the associated phase space construction, propose a meaningful definition of the Wigner function in this case, and characterize the set of pure states for which it is non-negative. We propose a measure of non-classicality for states in this system which is consistent with the continuum limit. The prescriptions introduced here are illustrated by applying them to localized and Gaussian states, and to their superpositions.

Be Star Surveys in Open Clusters with Balmer-line Photometry

2000

AbstractWe present CCD Hα and Hβ photometry of young open clusters. We show that the comparison of the α and β photometric indices provides an efficient tool for identifying emission line stars. We report on the discovery of several new Be stars.The preliminary results of our survey are the following: i. the younger clusters (age < 10 Myr) are almost lacking of Be stars, ii. clusters in the age interval 10–30 Myr are rich in Be stars. Almost all of them are of spectral types earlier than B5, while late-type Be stars are scarce. These results point towards an evolutionary interpretation of the Be phenomenon, in the sense that Be stars are close to the end of their main sequence lifetime.

Feynman-diagramme als vektorsysteme invariantentheoretisch behandelt (compton-streuung, elektron-positron-vernichtung

1985

Employing a special contact transformation devised by S. Lie, which takes spheres into lines, we interpret the Feynman diagrams of photon electron scattering in terms of vector systems. This gives a nice kinematic model of Compton scattering. We further compute in detail the transition probabilities of the Compton scattering process by making use of the calculus of chains of complexes from classical invariant theory rather than applying the usual Dirac-matrix technique. In the final paragraph of this paper an application of our calculations to the treatment of myon decay is indicated.

Elasticity of Poissonian fiber networks

2000

An effective-medium model is introduced for the elasticity of two-dimensional random fiber networks. These networks are commonly used as basic models of heterogeneous fibrous structures such as paper. Using the exact Poissonian statistics to describe the microscopic geometry of the network, the tensile modulus can be expressed by a single-parameter function. This parameter depends on the network density and fiber dimensions, which relate the macroscopic modulus to the relative importance of axial and bending deformations of the fibers. The model agrees well with simulation results and experimental findings. We also discuss the possible generalizations of the model. Peer reviewed

Poincaré Surface of Sections, Mappings

2001

We consider a system with two degrees of freedom, which we describe in four-dimensional phase space. In this (finite) space we define an (oriented) two-dimensional surface. If we then consider the trajectory in phase space, we are interested primarily in its piercing points through this surface. This piercing can occur repeatedly in the same direction. If the motion of the trajectory is determined by the Hamiltonian equations, then the n + 1-th piercing point depends only on the nth. The Hamiltonian thus induces a mapping n → n + 1 in the “Poincare surface of section” (PSS). The mapping transforms points of the PSS into other (or the same) points of the PSS. In the following we shall limit …

Topologies on Partial O*-Algebras

2002

In this chapter, we introduce some basic locally convex topologies on partial O*-algebras and we establish general properties of these topologies. In Section 4.1, we compare the graph topologies induced by different O-families on the same domain (and the corresponding families of bounded subsets). In the case where the domain D M of an O-family M is a (quasi-) Frechet space, the structure of bounded subsets in D M can be described in a rather explicit way. Section 4.2 and Section 4.3 are devoted to the topologization of (partial) O*-algebras. Section 4.2 deals with locally convex topologies, the so-called uniform topologies τ u , τ u , τ * u and quasiuniform topologies τ qu , and Section 4.…

Photoionization of Polarized Atoms Applications to Free Atoms and Ferromagnets

1996

Discussion of connections between different phenomena observed in seemingly different situations usually helps to better understanding of the physics of underlying processes. Some time ago Farago1 discussed analogies and contrasts between light polarization and electron spin polarization. He showed that though in both cases the same Stokes vector formalism2 can be applied, the analogies between them have rather limited validity. We will discuss here the applicability of equations derived for the description of photoionization of free polarized atoms3,4 to photoemission from ferromagnets5,6. We show that qualitative features of photoemission from core levels of ferromagnets are correctly rep…