A method to correct differential nonlinearities in subranging analog-to-digital converters used for digital gamma-ray spectroscopy

The influence on $\gamma$-ray spectra of differential nonlinearities (DNL) in subranging, pipelined analog-to-digital converts (ADCs) used for digital $\gamma$-ray spectroscopy was investigated. The influence of the DNL error on the $\gamma$-ray spectra, depending on the input count-rate and the dynamic range has been investigated systematically. It turned out, that the DNL becomes more significant in $\gamma$-ray spectra with larger dynamic range of the spectroscopy system. An event-by-event offline correction algorithm was developed and tested extensively. This correction algorithm works especially well for high dynamic ranges

Method for Selecting Improvement Measures for Discrete Production Environments Using an Extended Energy Value Stream Model

AbstractImproving energy efficiency in discrete manufacturing environments has been one of the key goals of recent research and industrial activities in production management, leading to a large and still increasing amount of different methodologies and improvement measures in that field (here called “Solution Elements”). Despite the growing interest, most of these are rarely applied, or are implemented in an improper manner instead of identifying and realizing the most appropriate ones from a holistic, factory wide perspective. For coping with these challenges a flexible, multi criteria and multi step selection process is introduced by which the applicability of solution elements is evaluated for a specific discrete production environment. The selection process is based on an approach taking multiple criteria derived from the current (as-is) situation in a factory as well as from user preferences into account. For data gathering an extended energy value stream approach is utilized that allows the derivation of value stream specific energy and cost drivers. The approach was tested in an industrial use-case, which is introduced in this paper

First-principles, atomistic thermodynamics for oxidation catalysis

Present knowledge of the function of materials is largely based on studies (experimental and theoretical) that are performed at low temperatures and ultra-low pressures. However, the majority of everyday applications, like e.g. catalysis, operate at atmospheric pressures and temperatures at or higher than 300 K. Here we employ ab initio, atomistic thermodynamics to construct a phase diagram of surface structures in the (T,p)-space from ultra-high vacuum to technically-relevant pressures and temperatures. We emphasize the value of such phase diagrams as well as the importance of the reaction kinetics that may be crucial e.g. close to phase boundaries.Comment: 4 pages including 2 figure files. Submitted to Phys. Rev. Lett. Related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

Identification of Normal Higher Aliphatic Aldehydes by Means of the Melting · Point Data of Their Thiosemicarbazones

The step-like alternations in melting points of both series of the aldehyde thiosemicarbazones, containing an even and an odd number of carbon atoms, are on average 10° for higher members of the homologous series. This lends itself well to an easy identification of higher aliphatic aldehydes

Jahn-Teller stabilization of a "polar" metal oxide surface: Fe3O4(001)

Using ab initio thermodynamics we compile a phase diagram for the surface of Fe3O4(001) as a function of temperature and oxygen pressures. A hitherto ignored polar termination with octahedral iron and oxygen forming a wave-like structure along the [110]-direction is identified as the lowest energy configuration over a broad range of oxygen gas-phase conditions. This novel geometry is confirmed in a x-ray diffraction analysis. The stabilization of the Fe3O4(001)-surface goes together with dramatic changes in the electronic and magnetic properties, e.g., a halfmetal-to-metal transition.Comment: 4 pages, 4 figure

Identification of Normal Higher Aliphatic Aldehydes by Means of the Melting · Point Data of Their Thiosemicarbazones

The step-like alternations in melting points of both series of the aldehyde thiosemicarbazones, containing an even and an odd number of carbon atoms, are on average 10° for higher members of the homologous series. This lends itself well to an easy identification of higher aliphatic aldehydes

A comparison between different propagative schemes for the simulation of tapered step index slab waveguides

The performance and accuracy of a number of propagative algorithms are compared for the simulation of tapered high contrast step index slab waveguides. The considered methods include paraxial as well as nonparaxial formulations of optical field propagation. In particular attention is paid to the validity of the paraxial approximation. To test the internal consistency of the various methods the property of reciprocity is verified and it is shown that for the paraxial algorithms the reciprocity can only be fulfilled if the paraxial approximation of the power flux expression using the Poynting vector is considered. Finally, modeling results are compared with measured fiber coupling losses for an experimentally realized taper structure

Analysis of OPM potentials for multiplet states of 3d transition metal atoms

We apply the optimized effective potential method (OPM) to the multiplet energies of the 3d$^n$ transition metal atoms, where the orbital dependence of the energy functional with respect to orbital wave function is the single-configuration HF form. We find that the calculated OPM exchange potential can be represented by the following two forms. Firstly, the difference between OPM exchange potentials of the multiplet states can be approximated by the linear combination of the potentials derived from the Slater integrals $F^2({\rm 3d,3d})$ and $F^4({\rm 3d,3d})$ for the average energy of the configuration. Secondly, the OPM exchange potential can be expressed as the linear combination of the OPM exchange potentials of the single determinants.Comment: 15 pages, 6 figures, to be published in J. Phys.