Johannes Kepler University of Linz

About: Johannes Kepler University of Linz is a education organization based out in Linz, Oberösterreich, Austria. It is known for research contribution in the topics: Thin film & Quantum dot. The organization has 6605 authors who have published 19243 publications receiving 385667 citations.

Analysis of FETI methods for multiscale PDEs

Abstract: In this paper, we study a variant of the finite element tearing and interconnecting (FETI) method which is suitable for elliptic PDEs with highly heterogeneous (multiscale) coefficients α(x); in particular, coefficients with strong variation within subdomains and/or jumps that are not aligned with the subdomain interfaces. Using energy minimisation and cut-off arguments we can show rigorously that for an arbitrary (positive) coefficient function $${\alpha \in L^\infty(\Omega)}$$the condition number of the preconditioned FETI system can be bounded by C(α) (1 + log(H/h))2 where H is the subdomain diameter and h is the mesh size, and where the function C(α) depends only on the coefficient variation in the vicinity of subdomain interfaces. In particular, if $${\alpha|_{\Omega_{i}}}$$varies only mildly in a layer Ω i,η of width η near the boundary of each of the subdomains Ω i , then $${C(\alpha) = \mathcal{O}((H/\eta)^2)}$$, independent of the variation of α in the remainder Ω i \Ω i,η of each subdomain and independent of any jumps of α across subdomain interfaces. The quadratic dependence of C(α) on H/η can be relaxed to a linear dependence under stronger assumptions on the behaviour of α in the interior of the subdomains. Our theoretical findings are confirmed in numerical tests.

Dependent Forms of Self-Employment in the UK: Identifying Workers on the Border between Employment and Self-Employment

Abstract: We analyse the characteristics of workers who provide work on the basis of a civil or commercial contract, but who are dependent on or integrated into the firm for which they work. We argue that these dependent self-employed lose their rights under labour law, receive less favourable benefits from social security protection and are often beyond trade union representation and collective bargaining. Using data from the British Labour Force Survey we test two hypotheses: (1) Dependent self-employed workers are significantly different from both employees and (independent) self-employed individuals, thus forming a distinct group. (2) Dependent selfemployed workers have lower labour market skills, less labour market attachment and, thus, less autonomy than self-employed workers. The data support our hypothesis that dependent selfemployed workers are a distinct labour market group which differs from both employees and independent self-employed individuals. Men, older workers, those with low education and a low job tenure have greater odds of working in dependent self-employment than their counterparts. Our results suggest that dependent forms of self-employment are used by firms to increase labour flexibility. (author's abstract)

Mechatronic Futures: Challenges and Solutions for Mechatronic Systems and their Designers

Abstract: Offering a comprehensive overview of the challenges, risks and options facing the future of mechatronics, this book provides insights into how these issues are currently assessed and managed. Building on the previously published book Mechatronics in Action, it identifies and discusses the key issues likely to impact on future mechatronic systems. It supports mechatronics practitioners in identifying key areas in design, modeling and technology and places these in the wider context of concepts such as cyber-physical systems and the Internet of Things. For educators it considers the potential effects of developments in these areas on mechatronic course design, and ways of integrating these. Written by experts in the field, it explores topics including systems integration, design, modeling, privacy, ethics and future application domains. Highlighting novel innovation directions, it is intended for academics, engineers and students working in the field of mechatronics, particularly those developing new concepts, methods and ideas.

The role of alkane dithiols in controlling polymer crystallization in small band gap polymer:Fullerene solar cells

Abstract: The effect of the addition of 1,8-octanedithiol (ODT) during processing on the microstructure of blend films of poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT) and [6,6]-phenyl-C71 butyric acid methyl ester ([70]PCBM) is studied. Grazing incidence X-ray diffraction and absorption spectroscopy show that the crystalline order of PCPDTBT increases when ODT is introduced in the solution phase either to neat polymer systems or to blends with [70]PCBM. The increased crystalline order is accompanied by less dispersive hole transport in the polymer, and leads to a more efficient formation of a percolating fullerene network within the blend. This contributes to an increase in photocurrent generation. However, the bimolecular recombination rate as determined from photovoltage transients increases upon addition of ODT, limiting the power conversion efficiency to values well below those expected from the energy levels of PCPDTBT. We propose some explanations for this increase in bimolecular recombination, based also on variable angle spectroscopic ellipsometry measurements. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011