3,859 research outputs found
Electronic Scattering Effects in Europium-Based Iron Pnictides
In a comprehensive study, we investigate the electronic scattering effects in
EuFe(AsP) by using Fourier-transform infrared
spectroscopy. In spite of the fact that Eu local moments order around
\,K, the overall optical response is strikingly similar
to the one of the well-known Ba-122 pnictides. The main difference lies within
the suppression of the lower spin-density-wave gap feature. By analysing our
spectra with a multi-component model, we find that the high-energy feature
around 0.7\,eV -- often associated with Hund's rule coupling -- is highly
sensitive to the spin-density-wave ordering, this further confirms its direct
relationship to the dynamics of itinerant carriers. The same model is also used
to investigate the in-plane anisotropy of magnetically detwinned
EuFeAs in the antiferromagnetically ordered state, yielding a
higher Drude weight and lower scattering rate along the crystallographic
-axis. Finally, we analyse the development of the room temperature spectra
with isovalent phosphor substitution and highlight changes in the scattering
rate of hole-like carriers induced by a Lifshitz transition
Roadmap to the multidisciplinary design analysis and optimisation of wind energy systems
A research agenda is described to further encourage the application of Multidisciplinary Design Analysis and Optimisation (MDAO) methodologies to wind energy systems. As a group of researchers closely collaborating within the International Energy Agency (IEA) Wind Task 37 for Wind Energy Systems Engineering: Integrated Research, Design and Development, we have identified challenges that will be encountered by users building an MDAO framework. This roadmap comprises 17 research questions and activities recognised to belong to three research directions: model fidelity, system scope and workflow architecture. It is foreseen that sensible answers to all these questions will enable to more easily apply MDAO in the wind energy domain. Beyond the agenda, this work also promotes the use of systems engineering to design, analyse and optimise wind turbines and wind farms, to complement existing compartmentalised research and design paradigms
A Study of Memetic Search with Multi-parent Combination for UBQP
We present a multi-parent hybrid genetic–tabu algorithm (denoted by GTA) for the Unconstrained Binary Quadratic Programming (UBQP) problem, by incorporating tabu search into the framework of genetic algorithm. In this paper, we propose a new multi-parent combination operator for generating offspring solutions. A pool updating strategy based on a quality-and-distance criterion is used to manage the population. Experimental comparisons with leading methods for the UBQP problem on 25 large public instances demonstrate the efficacy of our proposed algorithm in terms of both solution quality and computational efficiency
Tight-Binding model for semiconductor nanostructures
An empirical tight-binding (TB) model is applied to the
investigation of electronic states in semiconductor quantum dots. A basis set
of three -orbitals at the anions and one -orbital at the cations is
chosen. Matrix elements up to the second nearest neighbors and the spin-orbit
coupling are included in our TB-model. The parametrization is chosen so that
the effective masses, the spin-orbit-splitting and the gap energy of the bulk
CdSe and ZnSe are reproduced. Within this reduced TB-basis the
valence (p-) bands are excellently reproduced and the conduction (s-) band is
well reproduced close to the -point, i.e. near to the band gap. In
terms of this model much larger systems can be described than within a (more
realistic) -basis. The quantum dot is modelled by using the (bulk)
TB-parameters for the particular material at those sites occupied by atoms of
this material. Within this TB-model we study pyramidal-shaped CdSe quantum dots
embedded in a ZnSe matrix and free spherical CdSe quantum dots (nanocrystals).
Strain-effects are included by using an appropriate model strain field. Within
the TB-model, the strain-effects can be artifically switched off to investigate
the infuence of strain on the bound electronic states and, in particular, their
spatial orientation. The theoretical results for spherical nanocrystals are
compared with data from tunneling spectroscopy and optical experiments.
Furthermore the influence of the spin-orbit coupling is investigated
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Hanford Site environmental data for calendar year 1990 -- Ground water
This report tabulates ground-water radiological and chemical data for calendar year 1990 by the Ground-Water Surveillance Project, reported Resource Conservation and Recovery Act (RCRA) Monitoring, and Operational Monitoring. The Ground-Water Surveillance Project is conducted by the Pacific Northwest Laboratory and the RCRA and Operational Monitoring Projects are conducted by the Westinghouse Hanford Company. This document supplements the reports Hanford Site Ground-Water Monitoring for 1990 (Evans et al. 1992) and mental Report for Calendar Year 1990 (Woodruff and Hanf 1991). The data listings provided here were generated from the Hanford Environmental Information System database
Recommended from our members
Hanford Site environmental data for calendar year 1990 -- Ground water
This report tabulates ground-water radiological and chemical data for calendar year 1990 by the Ground-Water Surveillance Project, reported Resource Conservation and Recovery Act (RCRA) Monitoring, and Operational Monitoring. The Ground-Water Surveillance Project is conducted by the Pacific Northwest Laboratory and the RCRA and Operational Monitoring Projects are conducted by the Westinghouse Hanford Company. This document supplements the reports Hanford Site Ground-Water Monitoring for 1990 (Evans et al. 1992) and mental Report for Calendar Year 1990 (Woodruff and Hanf 1991). The data listings provided here were generated from the Hanford Environmental Information System database
The distribution and re-distribution of income of selfemployed as freelancers and entrepreneurs in Europe
The economic transformations of modern industrial societies have changed the labor markets in terms of
industrial relations and occupational structure. The transformation of the traditional welfare state, the
deregulation of the labor markets, the technological change and the reorganization of industrial structures
influenced strongly the attitude of individuals towards their preferred labor contract. The structural change of the
occupational structure was one of the results of this tendency. In particular the self-employed and freelancers
have been affected and are a driving factor of labor market changings. On the one side the value of autonomy
regarding industrial relations is becoming more important for employees. On the other side employers want to
get rid of social security contributions. As a result the multitudinousness of these professions increased.
The increasing varieties of occupations among the self-employed and freelancers influenced strongly their
income distribution. Recent studies for Germany have shown a great dispersion and a heterogeneous structure of
earnings in particular of freelancers (liberal professions) and self-employed. Though there are a variety of
international income distribution studies, but – as to the best to our knowledge – no study focusing on the selfemployed
and freelancers within the total labor force. In our study we concentrate on the income distribution of
self-employed and freelancers in different European countries. Based on the Luxembourg Income Study (LIS)
we analyze five different European countries and the United States structured by different types of welfare states
according to Esping Anderson. We analyze income distributional aspects, an occupational decomposition à la
Shorrocks, and re-distributional effects of the tax and transfer systems
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