arXiv subjects

Alexander Richter

Publications and source records attributed to Alexander Richter.

4 recordsLinked to original sources

arXiv2026

Thermodynamic Modeling of Pure Elements from 0 K with Uncertainty Quantification using PyCalphad and ESPEI

Thermodynamic modeling of pure elements is the foundation of the CALPHAD modeling of engineering materials. Recently, multiple physics-based models have been proposed to describe Gibbs energy of pure elements down to 0 K, extending from 298.15 K in the current CALPHAD modeling. To enable their systematic and quantitative comparison and adoption, those thermodynamic models of pure elements are implemented into the open-source software packages PyCalphad and ESPEI in the present work for evaluation of model parameters and model fitness. PyCalphad and ESPEI are suitable tools for implementation of these models for high throughput CALPHAD modeling of multicomponent materials. Particularly, Markov Chain Monte Carlo used in ESPEI allows for uncertainty quantification of model parameters and model predictions. Through the remodeling of 41 pure elements, the present work demonstrates the quantitative comparison of modeling of pure elements with different models and enables the efficient development of multicomponent systems with continuously improved CALPHAD description of pure elements.

cond-mat.mtrl-sci↗

arXiv2025

MASSLOC: A Massive Sound Source Localization System based on Direction-of-Arrival Estimation

Acoustic indoor localization offers the potential for highly accurate position estimation while generally exhibiting low hardware requirements compared to Radio Frequency (RF)-based solutions. Furthermore, angular-based localization significantly reduces installation effort by minimizing the number of required fixed anchor nodes. In this contribution, we propose the so-called MASSLOC system, which leverages sparse two-dimensional array geometries to localize and identify a large number of concurrently active sources. Additionally, the use of complementary Zadoff-Chu sequences is introduced to enable efficient, beamforming-based source identification. These sequences provide a trade-off between favorable correlation properties and accurate, unsynchronized direction-of-arrival estimation by exhibiting a spectrally balanced waveform. The system is evaluated in both a controlled anechoic chamber and a highly reverberant lobby environment with a reverberation time of 1.6 s. In a laboratory setting, successful direction-of-arrival estimation and identification of up to 14 simultaneously emitting sources are demonstrated. Adopting a Perspective-n-Point (PnP) calibration approach, the system achieves a median three-dimensional localization error of 55.7 mm and a median angular error of 0.84 deg with dynamic source movement of up to 1.9 mps in the challenging reverberant environment. The multi-source capability is also demonstrated and evaluated in that environment with a total of three tags. These results indicate the scalability and robustness of the MASSLOC system, even under challenging acoustic conditions.

eess.AS↗

arXiv2024

Use Cases for Prospective Sensemaking of Human-AI-Collaboration

This study explores the potential of Human-AI Collaboration (HAIC) use cases as a tool for prospective sensemaking. Based on 14 interviews with executives of an automotive company, we identify and categorize HAIC use cases that can help organizations anticipate and strategically respond to the impact of HAIC. Feedback from the case company shows that our systematic mapping of HAIC use cases along the value chain and group tasks enables a structured understanding of the potential role of AI and underscores the importance of strategic foresight when integrating AI into organizational processes.

cs.HC↗

arXiv2024

Circumventing cracking in grading 316L stainless steel to Monel400 through compositional modifications

In joining Fe-alloys and Cu-containing alloys to access the high strength of steels and corrosion resistance of Cu-alloy, cracking is widely observed due to the significant Cu microsegregation during the solidification process, resulting in an interdendritic Cu-rich liquid film at the end of solidification. By fabricating functionally graded materials (FGMs) that incorporate additional elements like Ni in the transition region between these terminal alloy classes, the hot cracking can be reduced. In the present work, the joining of stainless steel 316L (SS316L) and Monel400 by modifying the Ni concentration in the gradient region was studied. A new hot cracking criterion based on hybrid Scheil-equilibrium approach was developed and validated with monolithic multi-layer samples within the SS316L-Ni-Monel400 three-alloy system and an SS316L to 55/45 wt% SS316L/Ni to Monel400 FGM sample fabricated by direct energy deposition (DED) process. The new hot cracking criterion, based on the hybrid Scheil-equilibrium approach, is expected to help design FGM paths between other Fe-alloys and Cu-containing alloys as well.

cond-mat.mtrl-sci↗