05 Fakultät Informatik, Elektrotechnik und Informationstechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6
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Item Open Access High‐performance MEMS shutter display with metal‐oxide thin‐film transistors and optimized MEMS element(2023) Al Nusayer, Sheikh Abdullah; Schalberger, Patrick; Baur, Holger; Kleber, Florian; Fruehauf, NorbertActive matrix prestressed microelectromechanical shutter displays enable outstanding optical properties as well as robust operating performance. The microelectromechanical systems (MEMS) shutter elements have been optimized for higher light outcoupling efficiency with lower operation voltage and higher pixel density. The MEMS elements have been co-fabricated with self-aligned metal-oxide thin-film transistors (TFTs). Several optimizations were required to integrate MEMS process without hampering the performance of both elements. The optimized display process requires only seven photolithographic masks with ensuring proper compatibility between MEMS shutter and metal-oxide TFT process.Item Open Access Deep learning based soft sensors for industrial machinery(2020) Maschler, Benjamin; Ganssloser, Sören; Hablizel, Andreas; Weyrich, MichaelA multitude of high quality, high-resolution data is a cornerstone of the digital services associated with Industry 4.0. However, a great fraction of industrial machinery in use today features only a bare minimum of sensors and retrofitting new ones is expensive if possible at all. Instead, already existing sensors’ data streams could be utilized to virtually ‘measure’ new parameters. In this paper, a deep learning based virtual sensor for estimating a combustion parameter on a large gas engine using only the rotational speed as input is developed and evaluated. The evaluation focusses on the influence of data preprocessing compared to network type and structure regarding the estimation quality.Item Open Access Steered fiber orientation : correlating orientation and residual tensile strength parameters of SFRC(2022) Medeghini, Filippo; Guhathakurta, Jajnabalkya; Tiberti, Giuseppe; Simon, Sven; Plizzari, Giovanni A.; Mark, PeterAdding steel fibers to concrete improves the post-cracking tensile strength of the composite material due to fibers bridging the cracks. The residual performance of the material is influenced by fiber type, content and orientation with respect to the crack plane. The latter is a main issue in fiber-reinforced concrete elements, since it significantly influences the structural behavior. The aim of this research is to develop a tailor-made composite material and casting method to orient fibers in order to optimize the performance of the material for structural applications. To this aim, a mechanized concreting device that induces such preferred fiber orientation is designed and fabricated. It uses vibration and a series of narrow channels to guide and orient fibers. A composite with oriented fibers is produced using a hybrid system of macro and micro fibers and high-performance concrete. From the same concrete batch, specimens are cast both with and without the fiber orientation device, obtaining different levels of fiber orientation. Three-point bending tests are performed to measure and compare the residual tensile strength capacities with standard specimens cast according to EN 14651. Elements with favorable fiber orientation show a significant increase in residual tensile strength with respect to the standard beams. Finally, computed tomography and an electromagnetic induction method are employed to better assess the orientation and distribution of fibers in the beams. Their results are in good agreement and enable to link the residual tensile strength parameters with fiber orientation.Item Open Access Multi-method model for the investigation of disassembly scenarios for electric vehicle batteries(2023) Baazouzi, Sabri; Grimm, Julian; Birke, Kai PeterDisassembly is a pivotal technology to enable the circularity of electric vehicle batteries through the application of circular economy strategies to extend the life cycle of battery components through solutions such as remanufacturng, repurposing, and efficient recycling, ultimately reintegrating gained materials into the production of new battery systems. This paper aims to develop a multi-method self-configuring simulation model to investigate disassembly scenarios, taking into account battery design as well as the configuration and layout of the disassembly station. We demonstrate the developed model in a case study using a Mercedes-Benz battery and the automated disassembly station of the DeMoBat project at Fraunhofer IPA. Furthermore, we introduce two disassembly scenarios: component-oriented and accessibility-oriented disassembly. These scenarios are compared using the simulation model to determine several indicators, including the frequency of tool change, the number and distribution of robot routes, tool utilization, and disassembly time.Item Open Access Two-dimensional hole gases in SiGeSn alloys(2022) Oehme, Michael; Kasper, Erich; Weißhaupt, David; Sigle, Eric; Hersperger, Tim; Wanitzek, Maurice; Schwarz, DanielTwo-dimensional hole gases are demonstrated in modulation doped SixGe1-x-ySny quantum wells (QWs), which are embedded in Si0.2Ge0.8 barrier layers. The modulation doped QW structures are fabricated with molecular beam epitaxy on a thin (100 nm) virtual SiGe substrate on a (001) oriented Si substrate. The virtual substrate (VS) concept utilizes the Si diffusion into an as- grown thin, strain relaxed Ge layer during a following annealing step. The lateral lattice spacing of the SiGe-VS could be varied by the annealing temperature in the range between 830 °C and 860 °C. Half-hour anneal at 848 °C results in nearly strain free growth for the following Si0.2Ge0.8 barrier layer. Boron doping above an undoped 10 nm spacer on top of the 15 nm QW provides a reservoir for hole transfer from the barrier to the well. Electrical conductivity, sheet hole density ps and mobility are measured as function of temperature. In all investigated SixGe1-x-ySny channels the Hall measurements show the typical freeze out of holes outside the QW. Alloy scattering dominates the low-temperature mobility by adding Sn or Si to the Ge reference well. A linear relationship for the charge transfer from the modulation doping into the undoped SixGe1-x-ySny channel as function of the lattice mismatch between the channel material and the matrix material could be found at low-temperatures (8 K). An analytical model for this charge transfer confirms the nearly linear relationship by considering the triangular shape of the potential in modulation doped QW structures.Item Open Access User-friendly, requirement-based assistance for production workforce using an asset administration shell design(2020) Al Assadi, Anwar; Fries, Christian; Fechter, Manuel; Maschler, Benjamin; Ewert, Daniel; Schnauffer, Hans-Georg; Zürn, Michael; Reichenbach, MatthiasFuture production methods like cyber physical production systems (CPPS), flexibly linked assembly structures and the matrix production are characterized by highly flexible and reconfigurable cyber physical work cells. This leads to frequent job changes and shifting work environments. The resulting complexity within production increases the risk of process failures and therefore requires longer job qualification times for workers, challenging the overall efficiency of production. During operation, cyber physical work cells generate data, which are specific to the individual process and worker. Based on the asset administration shell for Industry 4.0, this paper develops an administration shell for the production workforce, which contains personal data (e.g. qualification level, language skills, machine access, preferred display and interaction settings). Using worker and process specific data as well as personal data, allows supporting, training and instating workers according to their individual capabilities. This matching of machine requirements and worker skills serves to optimize the allocation of workers to workstations regarding the ergonomic workplace setup and the machine efficiency. This paper concludes with a user-friendly, intuitive design approach for a personalized machine user interface. The presented use-cases are developed and tested at the ARENA2036 (Active Research Environment for the Next Generation of Automobiles) research campus.Item Open Access Understanding the impact of surface roughness : changing from FTO to ITO to PEN/ITO for flexible perovskite solar cells(2023) Holzhey, Philippe; Prettl, Michael; Collavini, Silvia; Mortan, Claudiu; Saliba, MichaelSo far, single-junction flexible PSCs have been lacking in efficiency compared to rigid PSCs. Recently, > 23% have been reported. We therefore focus on understanding the differences between rigid and flexible substrates. One often neglected parameter is the different surface roughness which directly affects the perovskite film formation. Therefore, we adjust the layer thickness of SnO2 and the perovskite layers. Furthermore, we introduce a PMMA layer between the perovskite and the hole transporting material (HTM), spiro-MeOTAD, to mitigate shunting pathways. In addition, the multication perovskite Rb0.02Cs0.05FA0.77MA0.16Pb(I0.83Br0.17)3 is employed, resulting in stabilized performances of 16% for a flexible ITO substrate and 19% on a rigid ITO substrate.