TY - GEN AB - In the Bogoliubov-Fr\"ohlich model, we prove that an impurity immersed in a Bose-Einstein condensate forms a stable quasi-particle when the total momentum is less than its mass times the speed of sound. The system thus exhibits superfluid behavior, as this quasi-particle does not experience friction. We do not assume any infrared or ultraviolet regularization of the model, which contains massless excitations and point-like interactions. AU - Hinrichs, Benjamin AU - Lampart, Jonas ID - 51376 T2 - arXiv:2311.05361 TI - A Lower Bound on the Critical Momentum of an Impurity in a Bose-Einstein Condensate ER - TY - JOUR AU - Fuchs, Christian ID - 46749 IS - 6 JF - Theory and Society TI - A Marxist-Humanist Perspective on Stuart Hall's Communication Theory VL - 52 ER - TY - JOUR AU - Burmeister, Sascha Christian AU - Guericke, Daniela AU - Schryen, Guido ID - 47431 JF - Flexible Services and Manufacturing Journal TI - A Memetic NSGA-II for the Multi-Objective Flexible Job Shop Scheduling Problem with Real-time Energy Tariffs ER - TY - CONF AU - Lenz, Cederic AU - Henke, Christian AU - Trächtler, Ansgar ID - 48570 T2 - 2023 IEEE 21st International Conference on Industrial Informatics (INDIN) TI - A Methodical Approach to Hybrid Modelling for Contextual Anomaly Detection on Time-Series Data ER - TY - JOUR AB - AbstractCold‐box sand (CBS) belongs to the granular materials and consists of sand and a binder. The behavior of CBS is simulated with a micropolar model, whereby the additional degree of freedom of the model describes the rotation of the sand grains. The model is used to generate a shear band under pressure for three different meshes, where the force‐displacement curves of the three meshes converge so that no mesh dependence occurs. Another requirement of the model is the consideration of asymmetric behavior for compression and tension. Due to the additional degree of freedom the implicit implementation of the micropolar continuum is very time‐consuming. Therefore, an explicit implementation is considered as an alternative possibility. This paper compares the advantages and disadvantages of both methods and the results for both calculations. AU - Börger, Alexander AU - Mahnken, Rolf ID - 52219 JF - PAMM KW - Electrical and Electronic Engineering KW - Atomic and Molecular Physics KW - and Optics SN - 1617-7061 TI - A micropolar model accounting for asymmetric behavior of cold‐box sand in relation to tensile and compression tests ER - TY - JOUR AU - Kurock, Ricarda AU - Teichert, Jeannine AU - Meister, Dorothee M. AU - Gerhardts, Lara AU - Buhl, Heike M. AU - Bonanati, Sabrina ID - 48370 IS - 14 JF - Journal of Adolescence TI - A mixed-methods study of the quality of parental support during adolescents' information-related Internet use as a co-construction process VL - 1 ER - TY - JOUR AB - I study the effect of heterogeneous beliefs about asset prices on the long-term behavior of financial markets. Starting from the ideas of Abreu and Brunnermeier (Citation2003), a two-dimensional system of differential equations is developed. The first dynamic variable is the asset price growth rate. The second dynamic variable is the number of investors who believe that asset prices are abnormally high. In a phase plane analysis, I find both stable and unstable equilibria, depending on the spread of information and the response to other agents’ beliefs. If individuals try to increase their returns while perceiving more overpricing, these equilibria can be spirals or even approach limit cycles. Although I intend to study general price patterns, abnormally high asset prices can be caused by financial bubbles. In this model, bubbles can emerge and deflate both in cycles or directly, or they can grow until they burst. Further, I analyze market behavior after a central bank increases the interest rate. This can lead to new stable equilibria, but the emergence and bursting of bubbles cannot be prevented. AU - Burs, Carina ID - 49309 IS - 2 JF - Cogent Economics & Finance KW - asset pricing KW - subjective information KW - stability conditions KW - monetary policy KW - risk aversion SN - 2332-2039 TI - A model of cycles and bubbles under heterogeneous beliefs in financial markets VL - 11 ER - TY - JOUR AB - We present strong enhancement of third harmonic generation in an amorphous silicon metasurface consisting of elliptical nano resonators. We show that this enhancement originates from a new type of multi-mode Fano mechanism. These ‘Super-Fano’ resonances are investigated numerically in great detail using full-wave simulations. The theoretically predicted behavior of the metasurface is experimentally verified by linear and nonlinear transmission spectroscopy. Moreover, quantitative nonlinear measurements are performed, in which an absolute conversion efficiency as high as ηmax ≈ 2.8 × 10−7 a peak power intensity of 1.2 GW cm−2 is found. Compared to an unpatterned silicon film of the same thickness amplification factors of up to ~900 are demonstrated. Our results pave the way to exploiting a strong Fano-type multi-mode coupling in metasurfaces for high THG in potential applications. AU - Hähnel, David AU - Golla, Christian AU - Albert, Maximilian AU - Zentgraf, Thomas AU - Myroshnychenko, Viktor AU - Förstner, Jens AU - Meier, Cedrik ID - 44097 IS - 1 JF - Light: Science & Applications KW - tet_topic_meta SN - 2047-7538 TI - A multi-mode super-fano mechanism for enhanced third harmonic generation in silicon metasurfaces VL - 12 ER - TY - GEN AB - Sparsity is a highly desired feature in deep neural networks (DNNs) since it ensures numerical efficiency, improves the interpretability of models (due to the smaller number of relevant features), and robustness. In machine learning approaches based on linear models, it is well known that there exists a connecting path between the sparsest solution in terms of the $\ell^1$ norm,i.e., zero weights and the non-regularized solution, which is called the regularization path. Very recently, there was a first attempt to extend the concept of regularization paths to DNNs by means of treating the empirical loss and sparsity ($\ell^1$ norm) as two conflicting criteria and solving the resulting multiobjective optimization problem. However, due to the non-smoothness of the $\ell^1$ norm and the high number of parameters, this approach is not very efficient from a computational perspective. To overcome this limitation, we present an algorithm that allows for the approximation of the entire Pareto front for the above-mentioned objectives in a very efficient manner. We present numerical examples using both deterministic and stochastic gradients. We furthermore demonstrate that knowledge of the regularization path allows for a well-generalizing network parametrization. AU - Amakor, Augustina Chidinma AU - Sonntag, Konstantin AU - Peitz, Sebastian ID - 51159 T2 - arXiv TI - A multiobjective continuation method to compute the regularization path of deep neural networks ER - TY - JOUR AU - Kruse, Stephan AU - Greitens, Jan C. AU - Schwabe, Tobias AU - Kneuper, Pascal AU - Kurz, Heiko G. AU - Scheytt, J. Christoph ID - 47126 JF - IEEE Microwave and Wireless Technology Letters TI - A Narrowband Four-Quadrant Electro-Optical Mixer for Microwave Photonics ER -