AIT Austrian Institute of Technology

Reliable determination of the elastic moduli of metals can be quite demanding, especially as the apparent elastic modulus of metals is known to decrease with deformation. Traditionally, this dependence on plastic strain has been investigated through various tensile tests, but discrepancies persist across the different approaches. Here we compare several tensile test-based evaluation protocols based on loading-unloading experiments to measure the change in elastic moduli of the light metal alloys AZ31B, EN AW-6082, and Ti–6Al–4V during tensile deformation. Additionally, the initial Young’s modulus determination via tensile testing, three-point-bending experiments, contact-free laser ultrasonic zero-group-velocity plate resonance, and piezoelectric contact ultrasonic time-of-flight measurements were compared. The results reveal non-negligible differences in the strain-dependency of elastic moduli between the determination techniques. Additionally, the laser ultrasound measurements demonstrate an improved accuracy and repeatability for the determination of the initial elastic moduli of light metal sheets. The benefit of considering the reduction of the elastic moduli in finite element springback simulation of three-point-bending tests is demonstrated and the use of the chord modulus is found to be generally most appropriate.

We demonstrate the stable trapping of a levitated nanoparticle at the apex of an inverted potential using a combination of optical readout and electrostatic control. The feedback levitation on an inverted potential (FLIP) method stabilizes the particle at an intensity minimum. By using a Kalman-filter-based linear-quadratic-Gaussian (LQG) control method, we confine a particle to within $\sigma _x={9\pm 0.5}\,\textrm{nm}$ of the potential maximum at an effective temperature of 16(1) K in a room-temperature environment. Despite drifts in the absolute position of the potential maximum, we can keep the nanoparticle at the apex by estimating the drift from the particle dynamics using the Kalman filter. Our approach may enable new levitation-based sensing schemes with enhanced bandwidth. It also paves the way for optical levitation at zero intensity of an optical potential, which alleviates decoherence effects due to material-dependent absorption and is hence relevant for macroscopic quantum experiments.

Within the EU Horizon 2020 project SHOW (GA No 875530) auxiliary measures, via evaluating and adapting physical road infrastructure (for instance lane markings, traffic signs, sight distances), as well as via digital support were explored for their potential contribution to enabling automated shared mobility services on the road environment. This line of research was then followed up on in the EU Horizon Europe Project AUGMENTED CCAM (GA 101,069,717), tackling more specifically with PDI support for automated mobility. This chapter presents the activities and findings of these two projects in relation to physical infrastructure adaptations for automated vehicles for two pilot sites in Austria.

As vehicle automation advances, integrating automated vehicles into the existing transportation system is crucial, considering technical but also social factors. This chapter investigates two Austrian pilot sites, Graz and Pörtschach, by assessing user preferences through a novel “supertester” approach that included experiential elements as well as interviews, questionnaires and workshops. The supertester approach is a within-subjects empirical method in which the same group of individuals experiences various use cases. Employing this approach allowed a comparative analysis across diverse settings, use cases, vehicle types and user perspectives. The study underscores the critical role of fundamental safety functions and the relation between different vehicle types and corresponding expectations of passengers.

In many transdisciplinary research settings, a lack of attention to the values underpinning project aims can inhibit stakeholder engagement and ultimately slow or undermine project outcomes. As a research collective (The Careoperative), we have developed a set of four shared values through a facilitated visioning process, as central to the way we work together: care, reflexivity, inclusivity, and collectivity. In this paper, we explore the implications of a values-centered approach to collaboration in food system transformation research. The paper presents two cases that illustrate how researchers might approach centering values in practice. Where much research on food system transformation focuses on values of food system stakeholders, we contribute insights into the values of researchers in such transdisciplinary endeavors. Specifically, we argue that researchers working on sustainability transformations need to be better prepared to engage in such reflections and aspire to embody values aligned with the transformations they seek to research.

Driven by an exponential growth of data, neuromorphic computing has risen in popularity as a new method for high-performance computing. The adopted neural network (NN) model relies on parallel processing between neurons and synapses, which reduces the energy consumption and boosts the computational efficiency. Photonics empowers neuromorphic processors through its inherent parallelism, along with high speed and unique bandwidth characteristics. Yet, it requires to transfer each constituent of the NN model to the optical realm, including the challenging nonlinear part of an activation function. Towards this direction, we experimentally demonstrate a photonic rectified linear unit (ReLU) function by employing frequency coding of neural signals in combination with a periodic optical filter. Furthermore, we show that multiple neural sub-circuits can be collapsed over the proposed photonic ReLU hardware and further evaluate the possibility to integrate weighting functionality with the frequency-domain ReLU as a way to further simplify the optical NN. For these demonstrations, we accomplish a low penalty of 1-3% in terms of accuracy when transferring the Iris flower classification challenge from the digital to the optical realm. Finally, we introduce an efficient translucent interface between the linear and nonlinear circuits of a photonic neuron, utilizing an optical frequency-coder that is directly driven by the photocurrent of a preceding photodetector – without the need for electrical amplification.

Digital signal processing (DSP) has become a cornerstone of optical signal transmission. Today, a plethora of tasks inherent to a wide range of optical communication systems are being transferred to the digital domain to perform signal shaping, modulation and recovery. At the same time, optical-layer subsystems are kept as lean as possible, even though they are recognized for their ample bandwidth and high degree of energy efficiency. Towards exploring these gains, we propose and experimentally demonstrate the concept of a multi-functional photonic processing node that is tasked to decode partial-response formats, to demodulate multi-level signals, to generate high-frequency radio signal carriers, to cancel crosstalk in full-duplex transmission schemes involving non-orthogonal modulation formats, and to perform neuromorphic signal processing. As we will demonstrate, all these tasks can be accomplished with a rather small set of photonic toolbox elements dedicated to an efficient electro-optic frequency translation and spectral signal manipulation. We prove that the majority of the aforementioned functions can be executed with superior performance when compared to DSP-based methods and with great potential for energy- and footprint-efficiency.

Zusammenfassung Die Einführung digitaler Technologien in Organisationen verändert Arbeitspraktiken und bietet das Potenzial, geschlechtsspezifische Machtstrukturen zu verändern. Allerdings werden in der betrieblichen Praxis durch die männlich dominierte Technologieentwicklung geschlechtsspezifische Ungleichheiten häufig eher reproduziert als abgebaut. Um das transformative Potenzial zu nutzen, ist eine aktive Gestaltung digitaler Veränderungsprozesse entscheidend, unter möglichst umfassender Einbindung unterschiedlicher Beschäftigtengruppen. Partizipative Ansätze können dabei die Einbindung unterrepräsentierter Gruppen ermöglichen. Dieser Artikel präsentiert zwei Fallstudien, in welchen partizipative Ansätze erprobt wurden. Organisation A konnte durch die Digitalisierung eines Arbeitsprozesses die Produktivität zwar erheblich steigern, in einem partizipativen Workshop wurden aber die Herausforderungen für die Beschäftigten sichtbar. Machtverschiebungen zugunsten traditionell als männlich konnotierter Arbeitsbereiche und der Verlust informellen Wissens weiblicher Beschäftigter wurden sichtbar. In Organisation B wurde eine digitale Kollaborationsplattform eingeführt, die allerdings wenig genutzt wurde. Im Rahmen eines Workshops mit administrativem Personal wurde erst das Potenzial und der Wunsch nach Beteiligung dieser Gruppe bei der Einführung neuer Technologien deutlich. Auf Basis dieser beiden Fallstudien reflektieren wir die geschlechtsbezogenen partizipativen Zugänge und die angewandten Forschungspraktiken. Darauf aufbauend formulieren wir praktische Empfehlungen zur Nutzung partizipativer Methoden in einem digitalen Transformationsprozess unter Berücksichtigung geschlechtsspezifischer Aspekte.

In this work, novel PET‐based frontsheet materials with UV‐cured coatings were developed and investigated. UV‐curing urethane acrylates were selected as innovative, fluorine‐free coating systems. Polyurethane coatings exhibit excellent UV resistance, chemical and moisture resistance and, thus, high durability in outdoor applications. A homogeneous application without coating defects such as bubbles, voids or detachments was achieved. Material tests with cross‐cut tests showed no separation from the PET substrate. The water vapor transmission rates and the physical (optical and thermal) and chemical properties of the novel polymeric frontsheets were measured and compared with uncoated reference systems and products already on the market. The aging‐related changes after irradiation and humid heat storage were investigated and described in detail. Based on this comprehensive study, the newly developed frontsheets can be considered a suitable alternative to polymeric frontsheets with fluorine‐containing top layers.

This survey provides an overview of combining federated learning (FL) and control to enhance adaptability, scalability, generalization, and privacy in (nonlinear) control applications. Traditional control methods rely on controller design models, but real‐world scenarios often require online model retuning or learning. FL offers a distributed approach to model training, enabling collaborative learning across distributed devices while preserving data privacy. By keeping data localized, FL mitigates concerns regarding privacy and security while reducing network bandwidth requirements for communication. This survey summarizes the state‐of‐the‐art concepts and ideas of combining FL and control. The methodical benefits are further discussed, culminating in a detailed overview of expected applications, from dynamical system modelling over controller design, focusing on adaptive control, to knowledge transfer in multi‐agent decision‐making systems.

This article introduces a unified structure for broadband and multi-band graphene-based absorbers. The absorption process relies on multiple circular graphene disks positioned on a glass surface. The absorber’s functionality can be adjusted from broad-band to multi-band by varying its height. To thoroughly assess its performance, we employed two theoretical frameworks: the transmission line model (TLM) and the Finite Element Method (FEM). Additionally, we conducted optical analysis using various incident wave polarizations. To validate our findings, we simulated the structure in the CST Studio simulator. The analysis reveals that the structure achieves over 90% absorption in the broad-band phase. Furthermore, it exhibits five absorption peaks: 28.1%, 99.9%, 98.1%, 94%, and 76% at frequencies of 0.3, 1, 2, and 2.7 THz, respectively, in the multi-band absorption phase.

Lithium-ion batteries, due to their high energy density, compact size, long lifetime, and low environmental impact, have achieved a dominant position in everyday life. These attributes have made them the preferred choice for powering portable devices such as laptops and smartphones, power tools, and electric vehicles. As technology advances rapidly, the demand for even more efficient energy storage devices continues to rise. In lithium-ion batteries, anodes play a crucial role, with lithium titanate oxide standing out as a highly promising material. This anode is favored for its exceptional cycle stability, safety features, and fast charging capabilities. The impressive cycle stability of lithium titanate oxide is largely due to its zero-strain nature, meaning it undergoes minimal volume changes during lithium-ion insertion and extraction. This stability enhances the anode’s durability, leading to longer battery life. In addition, the lithium titanate oxide anode operates at a voltage of approximately 1.55 V vs. Li⁺/Li, significantly reducing the risk of dendrite formation, a major safety concern that can cause short circuits and fires. The material’s spinel structure, with its large active surface area, further allows fast electron transfer and ion diffusion, facilitating fast charging. This review explores the characteristics of lithium titanate oxide, the various synthesis methods employed, and its integration with carbon materials to enhance cycle stability, coulombic efficiency, and safety. It also proposes strategies for optimizing lithium titanate oxide properties to create sustainable anodes with reduced environmental impact using eco-friendly routes.

Background Obesity is a complex, diverse and multifactorial disease that has become a major public health concern in the last decades. The current classification systems relies on anthropometric measurements, such as BMI, that are unable to capture the physiopathological diversity of this disease. The aim of this study was to redefine the classification of obesity based on the different H-NMR metabolomics profiles found in individuals with obesity to better assess the risk of future development of cardiometabolic disease. Materials and methods Serum samples of a subset of the Di@bet.es cohort consisting of 1387 individuals with obesity were analyzed by H-NMR. A K-means algorithm was deployed to define different H-NMR metabolomics-based clusters. Then, the association of these clusters with future development of cardiometabolic disease was evaluated using different univariate and multivariate statistical approaches. Moreover, machine learning-based models were built to predict the development of future cardiometabolic disease using BMI and waist-to-hip circumference ratio measures in combination with H-NMR metabolomics. Results Three clusters with no differences in BMI nor in waist-to-hip circumference ratio but with very different metabolomics profiles were obtained. The first cluster showed a metabolically healthy profile, whereas atherogenic dyslipidemia and hypercholesterolemia were predominant in the second and third clusters, respectively. Individuals within the cluster of atherogenic dyslipidemia were found to be at a higher risk of developing type 2 DM in a 8 years follow-up. On the other hand, individuals within the cluster of hypercholesterolemia showed a higher risk of suffering a cardiovascular event in the follow-up. The individuals with a metabolically healthy profile displayed a lower association with future cardiometabolic disease, even though some association with future development of type 2 DM was still observed. In addition, H-NMR metabolomics improved the prediction of future cardiometabolic disease in comparison with models relying on just anthropometric measures. Conclusions This study demonstrated the benefits of using precision techniques like H-NMR to better assess the risk of obesity-derived cardiometabolic disease.

Ti-6Al-4V has a wide range of applications, but long lead times and low-efficiency processing of the material leads to limitations. Through additive manufacturing, such as wire-arc directed energy deposition, higher processing efficiency, and lower lead times are possible. To fully realize the benefits, an important parameter for application is the fatigue performance, which needs to be better documented and performance shortcomings improved. Currently, available results on fatigue performance of wire-arc directed energy deposition of Ti-6Al-4V are limited. Therefore, wire-arc directed energy deposition of Ti-6Al-4V was used with the following approach. Samples were characterized using scanning electron microscopy and optical light microscopy, and mechanically tested for tensile and fatigue performance. Minimal pore density and a fine α microstructure within coarsened epitaxial columnar β-grains was observed. Additionally, elemental burn-off and oxygen contamination was assessed, showing a loss of 0.2 wt.% aluminum during processing and no oxygen pick-up. Compared to other cold metal transfer-based wire-arc directed energy deposition results available in the literature, the results present significant improvements. Fractography indicated mixed fracture modes, which are likely due to the macro-zones of α having varying orientations. Our work provides an advancement in fatigue performance and processing, further showing the potential of the technology.