Introducing many-body physics using atomic spectroscopy

Atoms constitute relatively simple many-body systems, making them suitable objects for developing an understanding of basic aspects of many-body physics. Photoabsorption spectroscopy is a prominent method to study the electronic structure of atoms and the inherent many-body interactions. In this article the impact of many-body effects on well-known spectroscopic features such as Rydberg series, Fano resonances, Cooper minima, and giant resonances is studied, and related many-body phenomena in other fields are outlined. To calculate photoabsorption cross sections the time-dependent configuration interaction singles (TDCIS) model is employed. The conceptual clearness of TDCIS in combination with the compactness of atomic systems allows for a pedagogical introduction to many-body phenomena.Comment: 15 pages, 6 figures, 1 table. The following article has been accepted by American Journal of Physic

Documentation of scales implemented from panel wave 1 onwards

This paper documents the questionnaire-based scales and item composites administered in the first two waves of the second TREE cohort (TREE2) in 2017 and 2018. At the centre of this working paper is a technical appendix, which provides, for each scale, a detailed tabular report of selected statistics and quality measures. The focus is on the scales’ reliability, dimensionality and measurement invariance. The scaling and calculation of factor scores rely essentially on the same factor-analytical models and methods as in the TREE2 baseline survey. These are described in detail in sec-tion 3 of the respective documentation of the scales used in that survey (see Sacchi & Krebs-Oesch, 2021). The documentation also describes the selection, calculation and interpretation of the figures and quality measures reported in the tabular appendix (ibid., section 4). Against this backdrop, the explanatory notes in the introduction of the present documenta-tion are restricted to a description of the database for both waves and of some modifications in the applied methods. In addition, we also describe a series of newly introduced statistics of longitudinal measurement invariance for scales with repeated measures

Scaling methodology and scale reporting in the TREE2 panel survey. Documentation of scales implemented in the baseline survey (2016). Update 2023

This documentation refers to the database of the 2nd TREE cohort’s (TREE2) as published in the 2023 data release (TREE, 2023). It outlines the statistical models and estimation methods employed for scale construction and the calculation of student scores based on questionnaire items. Furthermore, we discuss the various metrics and indicators of relevant scale propertiescompiled in the technical appendix for all scales implemented in the TREE2 baseline survey. The focus of the scale reporting is on the internal consistency of the scales and on the comparability of the measurements across survey languages, survey modes and survey settings involved. With very few exceptions, the results indicate at least sufficient or high internal consistency and measurement invariance of the scales used. A complementary documentation covering the scales employed in later panel waves can be found in the 2023 TREE2 data release (Sacchi & Krebs-Oesch, 2023). With the exception of a few additional metrics of longitudinal measurement invariance over panels waves (ibid., sections 3.6, 4.2), it basically relies on the methods presented in this report

Guaranteed state estimation using a bundle of interval observers with adaptive gains applied to the induction machine

he scope of this paper is the design of an interval observer bundle for the guaranteed state estimation of an uncertain induction machine with linear, time-varying dynamics. These guarantees are of particular interest in the case of safety-critical systems. In many cases, interval observers provide large intervals for which the usability becomes impractical. Hence, based on a reduced-order hybrid interval observer structure, the guaranteed enclosure within intervals of the magnetizing current’s estimates is improved using a bundle of interval observers. One advantage of such an interval observer bundle is the possibility to reinitialize the interval observers at specified timesteps during runtime with smaller initial intervals, based on previously observed system states, resulting in decreasing interval widths. Thus, unstable observer dynamics are considered so as to take advantage of their transient behavior, whereby the overall stability of the interval estimation is maintained. An algorithm is presented to determine the parametrization of reduced-order interval observers. To this, an adaptive observer gain is introduced with which the system states are observed optimally by considering a minimal interval width at variable operating points. Furthermore, real-time capability and validation of the proposed methods are shown. The results are discussed with simulations as well as experimental data obtained with a test bench

Scaling methodology and scale reporting in the TREE2 panel survey. Documentation of scales implemented in the baseline survey (2016)

This paper documents the questionnaire-based scales and item-based composites that have been collected on the occasion of the baseline survey administered to the second TREE cohort (TREE2) in 2016. First, the paper focuses on the methods and the estimation procedures that we have adopted for the calculation of the student scores published in the scientific use data files. Second, we describe the calculation of scale-specific statistics and quality measures (reported in the technical appendix) and provide some clues for their interpretation

Intervallbeobachter für lineare parametervariante Systeme und deren Anwendung auf die Asynchronmaschine

Diese Arbeit widmet sich der Entwicklung zweier neuer Methoden zur Bestimmung von Zustandsmengen für lineare parametervariante Systeme. Erzeugt werden diese Zustandsmengen in Form von Intervallvektoren durch Intervallbeobachter auf Basis von unbekannten, aber beschränkten Unsicherheiten der Ein-/ Ausgangsgrößen und der Parameter. In Kombination mit einem neuartigen Intervallmodell des Wechselrichters wird die Wirksamkeit der Methoden am Beispiel der Asynchronmaschine gezeigt

“Sobbing, Whining, Rumbling” – Listening to Automobiles as Social Practice

Who listened to cars in the 1920s? Who listened to the sound of its technical malfunctions in the 1950s? Who were the experts to diagnose failures by their ‘golden ears’ (Perlman 2004)? What role did listening play in early automobility? To answer these questions, my paper will analyze how different actor groups in Germany listened to automobiles between the end of World War I and roughly 1960. Further, I’ll focus on car technology’s middle ground – the space between production and consumption (Borg 2007: 1–12). In other words, I’ll closely examine the difficult relations between car users and auto mechanics. While in the 1920s car manufacturers started advertising the silent run of their engines, gears and suspensions, listening to the sound of their automobiles still played an essential role for car users to notice any technical malfunctions. The verbalization of the sound experience was a legitimate and crucial means for error detection. Motorists wrote, for example, to the magazine of the German automobile club, ‘Allgemeine Automobil-Zeitung’, and tried to express their audio evidence with a wide range of metaphors or by relating it to other common sound experiences: their cars were ‘sobbing, whining or rumbling’. Still in the 1930s these descriptions were regularly printed in a column called the ‘letter box’ and experts gave technical advices on their basis. Two decades later things had changed: While listening was still a central means for detecting faults, it was reserved to the ‘trained ears’ of car mechanics only. Instead the professionals made a mock of drivers who listened to their cars: the trade journal ‘Krafthand’ told the story of a car owner who claimed that his car was making a strange splashing noise. But during the inspection the mechanics couldn’t find any faults. Later it was discovered that the sound was merely the echo of avenue trees, which irritated the driver while going past. The moral of articles like this one was, that the ears of ordinary motorists lacked the necessary training to listen to their automobiles. The paper will argue that the observed change of the notion of listening to cars can be explained by using Pierre Bourdieu’s ‘praxeology’: e.g., by conceptualising the here roughly sketched conversion as a symbolic struggle between motorists and auto mechanics about who is the real car sound expert. Then, the stories in the trade journal can be read as descriptions of the auto mechanics habitus, or more precisely: their bodily hexis (Bourdieu 1987: 739). The ability to diagnose malfunctions by listening to the sound of broken-down automobiles became part of the incorporated bodily knowledge of car mechanics. The struggle can thus be interpreted as a negotiation of status: the claim for the exclusive right to listen is then part of the sociotechnical distinction between lay motorists and expert car mechanics. The recurring descriptions of the motorists’ ‘bad ears’ are part of a discursive construction of normal motorists as lay users. Narrations like these are told to exclude motorists from the expert discourse. However motorists always heard their cars while driving, and they still had to listen whether their cars were running well. That is, on a practical level, mechanics couldn’t prevent users from listening, only on a symbolic level they denied access to the realm of car sound as means for technical diagnosis. Due to this contradictory status of listening as an indispensable means to detect malfunctions and listening as an expert tool for detailed diagnosis, users contested the expert authority of auto mechanics. For analyzing the role of listening in automobility I’ll investigate trade journals for auto mechanics, special interest journals for motorists, car manuals and technical handbooks. I’ll take into account editorials, articles and requests for reader’s experiences, advertisements and cartoons. As methodological means I’ll use thick description, and embed the struggle between motorists and mechanics into the historical context of early German automobility, e.g., the change in car functions and properties. For analyzing the empirical findings I’ll refer to the vocabulary of the theory of social practices

Silent by Design? Tesla’s Model S and the Discourse on Electric Vehicle Sound

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