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: Computer science & Thin film. The organization has 6605 authors who have published 19243 publications receiving 385667 citations.

Indigo and Tyrian Purple – From Ancient Natural Dyes to Modern Organic Semiconductors

Abstract: We describe the history of indigo dye and its deriv- ative Tyrian purple, from their roles in the ancient world to recent research showing the semiconducting properties of indigoids. Indigoids are natural dyes that have been pro- duced for centuries, and indigo is currently the most pro- duced dye worldwide. Herein we review the history of these materials, their chemistry and physical properties, and their semiconducting characteristics in the solid state. Due to hy- drogen bonding and p-stacking, indigo and Tyrian purple form highly-ordered crystalline thin films. Such films have been used to fabricate high-performance organic field-effect transistors with ambipolar charge transport, as well as com- plementary-like circuits. Mobility values were found to be in the range of 10 � 2 -0.4 cm 2 /Vs. With performance on par with the best available organic semiconductors, indigoids dem- onstrate the potential of sustainable electronics based on biodegradable and biocompatible materials.

Does Education Improve Cognitive Performance Four Decades After School Completion

Abstract: We study the effect of secondary education on cognitive performance toward the end of working age. We exploit the exogenous variation in years of schooling arising from compulsory schooling reforms implemented in six European countries during the 1950s and 1960s. Using data of individuals, approximately age 60, from the Survey of Health, Ageing and Retirement in Europe (SHARE), we assess the causal effect of education on memory, fluency, numeracy, and orientation-to-date. Furthermore, we study education effects on cognitive decline. We find a positive impact of schooling on memory scores. One year of education increases the memory score approximately four decades later by about 0.2, which amounts to 10 % of a standard deviation. Furthermore, we find some evidence for a protective effect of schooling on cognitive decline in terms of verbal fluency.

A model predictive Cooperative Adaptive Cruise Control approach

Abstract: Reduction of fuel consumption is one of the primary goals of modern automotive engineering. While in the past the focus was on more efficient engine design and control there is an upcoming interest on economic context aware control of the complete vehicle. Technical progress will enable future vehicles to interact with other traffic participants and the surrounding infrastructure, collecting information which allow for reduction of fuel consumption by predictive vehicle control strategies. The principle of Model Predictive Control allows a straightforward integration of e.g. navigation systems, on-board radar sensors, V2V- and V2I-communication whilst regarding constraints and dynamic of the system. This paper presents a Linear Model Predictive Control approach to Cooperative Adaptive Cruise Control, directly minimizing the fuel consumption rather than the acceleration of the vehicle. To this end the nonlinear static fuel consumption map of the internal combustion engine is included into the control design by a piecewise quadratic approximation. Inclusion of a linear spacing policy prevents rear end collisions. Simulation results demonstrate the fuel and road capacity benefits, for a single vehicle and for a string of vehicles, equipped with the proposed control, in comparison to vehicles operated by a non-cooperative adaptive cruise control. Full information on the speed prediction of the predecessor is assumed, hence the purpose of this paper is twofold. On the one hand, best achievable benefits, of the proposed control, due to perfect prediction are demonstrated. On the other hand, the paper studies the behavior of the considered control and the influence of the prediction horizon.

High yield and ultrafast sources of electrically triggered entangled-photon pairs based on strain-tunable quantum dots.

Abstract: Triggered sources of entangled photon pairs are key components in most quantum communication protocols. For practical quantum applications, electrical triggering would allow the realization of compact and deterministic sources of entangled photons. Entangled-light-emitting-diodes based on semiconductor quantum dots are among the most promising sources that can potentially address this task. However, entangled-light-emitting-diodes are plagued by a source of randomness, which results in a very low probability of finding quantum dots with sufficiently small fine structure splitting for entangled-photon generation (∼10(-2)). Here we introduce strain-tunable entangled-light-emitting-diodes that exploit piezoelectric-induced strains to tune quantum dots for entangled-photon generation. We demonstrate that up to 30% of the quantum dots in strain-tunable entangled-light-emitting-diodes emit polarization-entangled photons. An entanglement fidelity as high as 0.83 is achieved with fast temporal post selection. Driven at high speed, that is 400 MHz, strain-tunable entangled-light-emitting-diodes emerge as promising devices for high data-rate quantum applications.