Simulation based case studies for management training in the fields of production and supply chain Management

It is well known that interactive learning is much more efficient than classical learning with textbooks. With the broad propagation of computers, new opportunities for computer-based interactive learning are available. In particular, simulation based learning allows the student to learn based on experience. In economic and technical environments, where complex systems comprise numerous decision variables, conducting experiments can provide a deeper insights and an intuitive understanding to the student. In the present paper, a newly developed environment for computer-based interactive learning in the fields of production and supply chain training is described. The different steps from the evaluation of an appropriate electronic platform to the development of eight different case studies for the students are explained. The environment now provides an easily applicable and ready-to-use solution for university teachers and their students

Shape Holomorphy of the stationary Navier-Stokes Equations *

We consider the stationary Stokes and Navier-Stokes Equations for viscous, incompressible flow in parameter dependent bounded domains D T , subject to homogeneous Dirichlet (" no-slip ") boundary conditions on ∂D T. Here, D T is the image of a given fixed nominal Lipschitz domainˆDdomainˆ domainˆD ⊆ R d , d ∈ {2, 3}, under a map T : R d → R d. We establish shape holomorphy of Leray solutions which is to say, holomorphy of the map T → (ˆ u T , ˆ p T) where (ˆ u T , ˆ p T) ∈ H 1 0 (ˆ D) d ×L 2 (ˆ D) denotes the pullback of the corresponding weak solutions and T varies in W k,∞ with k ∈ {1, 2}, depending on the type of pullback. We consider in particular parametrized families {T y : y ∈ U } ⊆ W 1,∞ of domain mappings, with parameter domain U = [−1, 1] N and with affine dependence of T y on y. The presently obtained shape holomorphy implies summability results and n-term approximation rate bounds for gpc (" generalized polynomial chaos ") expansions for the corresponding parametric solution map y → (ˆ u y , ˆ p y) ∈ H 1 0 (ˆ D) d × L 2 (ˆ D)

Catalytic Low-Temperature Dehydration of Fructose to 5-Hydroxymethylfurfural Using Acidic Deep Eutectic Solvents and Polyoxometalate Catalysts

HMF synthesis typically requires high temperature and is carried out in aqueous solutions. In this work, the low-temperature dehydration of fructose to HMF in different deep eutectic solvents (DES) was investigated. We found a very active and selective reaction system consisting of the DES tetraethyl ammonium chloride as hydrogen bond acceptor (HBA) and levulinic acid as hydrogen bond donor (HBD) in a molar ratio of 1:2 leading to a maximum HMF yield of 68% after 120 h at 323 K. The DES still contained a low amount of water at the initial reaction, and water was also produced during the reaction. Considering the DES properties, neither the molar ratio in the DES nor the reaction temperature had a significant influence on the overall performance of the reaction system. However, the nature of the HBA as well as the acidity of the HBD play an important role for the maximum achievable HMF yield. This was validated by measured yields in a DES with different combinations of HBD (levulinic acid and lactic acid) and HBA (choline chloride and tetra-n-alkyl ammonium chlorides). Moreover, addition of vanadium containing catalysts, especially the polyoxometalate HPA-5 (H8PV5Mo7O40) leads to drastically increased reaction kinetics. Using HPA-5 and the DES tetraethyl ammonium chloride—levulinic acid we could reach a maximum HMF yield of 57% after only 5 h reaction time without decreasing the very high product selectivity

How climate change reallocates labour and capital within countries

The negative impact of climate change on local economic activity has been well studied. However, so far, we have lacked a clear understanding of how it affects the allocation of labour and capital. Christoph Albert, Paula Bustos, and Jacopo Ponticelli use new data on extreme weather events that occurred in Brazil during the last two decades and write that prolonged droughts cause the reallocation of capital and labour away from affected regions, effectively changing the structure of the economy in both directly affected areas and those integrated via labour and capital markets

RWTH ASR Systems for LibriSpeech: Hybrid vs Attention -- w/o Data Augmentation

We present state-of-the-art automatic speech recognition (ASR) systems employing a standard hybrid DNN/HMM architecture compared to an attention-based encoder-decoder design for the LibriSpeech task. Detailed descriptions of the system development, including model design, pretraining schemes, training schedules, and optimization approaches are provided for both system architectures. Both hybrid DNN/HMM and attention-based systems employ bi-directional LSTMs for acoustic modeling/encoding. For language modeling, we employ both LSTM and Transformer based architectures. All our systems are built using RWTHs open-source toolkits RASR and RETURNN. To the best knowledge of the authors, the results obtained when training on the full LibriSpeech training set, are the best published currently, both for the hybrid DNN/HMM and the attention-based systems. Our single hybrid system even outperforms previous results obtained from combining eight single systems. Our comparison shows that on the LibriSpeech 960h task, the hybrid DNN/HMM system outperforms the attention-based system by 15% relative on the clean and 40% relative on the other test sets in terms of word error rate. Moreover, experiments on a reduced 100h-subset of the LibriSpeech training corpus even show a more pronounced margin between the hybrid DNN/HMM and attention-based architectures.Comment: Proceedings of INTERSPEECH 201

Breaking the curse of dimensionality in sparse polynomial approximation of parametric PDEs

The numerical approximation of parametric partial differential equations D(u,y)=0 is a computational challenge when the dimension d of of the parameter vector y is large, due to the so-called curse of dimensionality. It was recently shown that, for a certain class of elliptic PDEs with diffusion coefficients depending on the parameters in an affine manner, there exist polynomial approximations to the solution map u -> u(y) with an algebraic convergence rate that is independent of the parametric dimension d. The analysis used, however, the affine parameter dependence of the operator. The present paper proposes a strategy for establishing similar results for some classes parametric PDEs that do not necessarily fall in this category. Our approach is based on building an analytic extension z->u(z) of the solution map on certain tensor product of ellipses in the complex domain, and using this extension to estimate the Legendre coefficients of u. The varying radii of the ellipses in each coordinate zj reflect the anisotropy of the solution map with respect to the corresponding parametric variables yj. This allows us to derive algebraic convergence rates for tensorized Legendre expansions in the case where d is infinite. We also show that such rates are preserved when using certain interpolation procedures, which is an instance of a non-intrusive method. As examples of parametric PDE's that are covered by this approach, we consider (i) elliptic diffusion equations with coefficients that depend on the parameter vector y in a not necessarily affine manner, (ii) parabolic diffusion equations with similar dependence of the coefficient on y, (iii) nonlinear, monotone parametric elliptic PDE's, and (iv) elliptic equations set on a domain that is parametrized by the vector y. We give general strategies that allows us to derive the analytic extension in a unified abstract way for all these examples, in particular based on the holomorphic version of the implicit function theorem in Banach spaces. We expect that this approach can be applied to a large variety of parametric PDEs, showing that the curse of dimensionality can be overcome under mild assumptions

Mixed Reality UI Adaptations with Inaccurate and Incomplete Objectives

This position paper outlines a new approach to adapting 3D user interface (UI) layouts given the complex nature of end-user preferences. Current optimization techniques, which mainly rely on weighted sum methods, can be inflexible and result in unsatisfactory adaptations. We propose using multi-objective optimization and interactive preference elicitation to provide semi-automated, flexible, and effective adaptations of 3D UIs. Our approach is demonstrated using an example of single-element 3D layout adaptation with ergonomic objectives. Future work is needed to address questions around the presentation and selection of optimal solutions, the impact on cognitive load, and the integration of preference learning. We conclude that, to make adaptive 3D UIs truly effective, we must acknowledge the limitations of our optimization objectives and techniques and emphasize the importance of user control.Comment: Published in CHI 2023 Workshop on Future of Computational Approaches for Understanding and Adapting User Interfaces: ACM CHI Conference on Human Factors in Computing Systems, April 23, 2023, Hamburg, Germany, 6 page

Politikwissenschaftliche Polarforschung

Vor dem Hintergrund des nunmehr auch im deutschsprachigen Raum gestiegenen politikwissenschaftlichen Interesses an Polarforschung identifiziert dieser Beitrag aus drei Perspektiven Forschungsstränge, von denen Impulse für einen intensivierten Austausch zwischen politik- und naturwissenschaftlicher Polarforschung ausgehen könnten: die Makroperspektive nimmt Dynamiken und Regulierung des Erdsystems in den Blick; die Mesoperspektive die Organisation von Beziehungen zwischen Wissenschaft und Politik in institutionellen Designs und Prozessen; die Mikroperspektive schließlich das Zusammenspiel verschiedener Akteure bei der Politikgestaltung und -implementation.</p

mTORC2 sustains thermogenesis via Akt-induced glucose uptake and glycolysis in brown adipose tissue

Activation of non-shivering thermogenesis (NST) in brown adipose tissue (BAT) has been proposed as an anti-obesity treatment. Moreover, cold-induced glucose uptake could normalize blood glucose levels in insulin-resistant patients. It is therefore important to identify novel regulators of NST and cold-induced glucose uptake. Mammalian target of rapamycin complex 2 (mTORC2) mediates insulin-stimulated glucose uptake in metabolic tissues, but its role in NST is unknown. We show that mTORC2 is activated in brown adipocytes upon β-adrenergic stimulation. Furthermore, mice lacking mTORC2 specifically in adipose tissue (AdRiKO mice) are hypothermic, display increased sensitivity to cold, and show impaired cold-induced glucose uptake and glycolysis. Restoration of glucose uptake in BAT by overexpression of hexokinase II or activated Akt2 was sufficient to increase body temperature and improve cold tolerance in AdRiKO mice. Thus, mTORC2 in BAT mediates temperature homeostasis via regulation of cold-induced glucose uptake. Our findings demonstrate the importance of glucose metabolism in temperature regulation