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Identification of dynamic models for the short-term temperature prediction in a single room

IFAC-PapersOnLine 2018年第2期51卷 79-84页

作者： Paschke, Fabian Zaiczek, Tobias Fraunhofer IIS/EAS Fraunhofer Institute for Integrated Circuits Division Engineering of Adaptive Systems Dresden Germany

This contribution illustrates an approach for the generation of a linear dynamic discrete time model for the short term prediction of the room temperature in a single conference room. The model is extracted from recorded measurement data by means of system identification. After a brief description of the considered room and the modeling approach the model is validated by statistical analysis and by its prediction performance. © 2018

关键词： Model predictive control

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Advances in Modeling of the Kerf Formation considering the Primary and Deflection Jets for the Abrasive Water Jet Technology

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Procedia CIRP 2021年 102卷 156-161页

作者： Eckart Uhlmann Harald Kruggel-Emden Constantin Männel Enrico Barth Darius Markauskas Technische Universität Berlin Institute for Machine Tools and Factory Management (IWF) Pascalstr. 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology (IPK) Pascalstr. 8-9 10587 Berlin Germany Technische Universität Berlin Mechanical Process Engineering and Solids Processing Ernst-Reuter-Platz 1 10587 Berlin

Processing of difficult to machine materials is a promising application for abrasive water jet kerf cutting and milling. However, due to the large number of interactions of an energy-bound cutting process, a precise prediction of the material removal is crucial for its application. Based on an analytical approach, a material removal simulation model is introduced considering the primary and deflecting jet impacts to rapidly predict various cutting situations. The model describes fundamental cutting mechanisms considering the water jet’s material removal rate and is calibrated for titanium aluminides. The model allows for a comprehensive kerf prediction and thus potentially accelerates the process design improving the productivity and quality for abrasive water jet kerf cutting and milling.

关键词： Waterjet machining Titanium aluminides AWJ milling Modeling AWJ deflection

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A single T-gate makes distribution learning hard

arXiv

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arXiv 2022年

作者： Hinsche, Marcel Ioannou, Marios Nietner, Alexander Haferkamp, Jonas Quek, Yihui Hangleiter, Dominik Seifert, Jean-Pierre Eisert, Jens Sweke, Ryan Dahlem Center for Complex Quantum Systems Freie Universität Berlin Berlin14195 Germany University of Maryland & NIST College ParkMD20742 United States Department of Electrical Engineering and Computer Science TU Berlin Berlin10587 Germany Helmholtz-Zentrum Berlin für Materialien und Energie Berlin14109 Germany Fraunhofer Heinrich Hertz Institute Berlin10587 Germany

The task of learning a probability distribution from samples is ubiquitous across the natural sciences. The output distributions of local quantum circuits form a particularly interesting class of distributions, of key importance both to quantum advantage proposals and a variety of quantum machine learning algorithms. In this work, we provide an extensive characterization of the learnability of the output distributions of local quantum circuits. Our first result yields insight into the relationship between the efficient learnability and the efficient simulatability of these distributions. Specifically, we prove that the density modelling problem associated with Clifford circuits can be efficiently solved, while for depth d = nΩ(1) circuits the injection of a single T-gate into the circuit renders this problem hard. This result shows that efficient simulatability does not imply efficient learnability. Our second set of results provides insight into the potential and limitations of quantum generative modelling algorithms. We first show that the generative modelling problem associated with depth d = nΩ(1) local quantum circuits is hard for any learning algorithm, classical or quantum. As a consequence, one cannot use a quantum algorithm to gain a practical advantage for this task. We then show that, for a wide variety of the most practically relevant learning algorithms – including hybrid-quantum classical algorithms – even the generative modelling problem associated with depth d = ω(log(n)) Clifford circuits is hard. This result places limitations on the applicability of near-term hybrid quantum-classical generative modelling algorithms. © 2022, CC BY-NC-SA.

关键词： Learning algorithms

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5G Internet of Radio Light Positioning System for Indoor Broadcasting Service

5G Internet of Radio Light Positioning System for Indoor Bro...

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作者： Shi, Lina Shi, Dayu Zhang, Xun Meunier, Benjamin Zhang, Hequn Wang, Zhan Vladimirescu, Andrei Li, Wei Zhang, Yue Cosmas, John Ali, Kareem Jawad, Nawar Zetik, Rudolf Legale, Eric Satta, Matteo Wang, Jintao Song, Jian Department of Electronic and Computer Engineering Institute Supérieur d'Electronique de Paris Paris75006 France Department of Electronic and Computer Engineering Brunel University UxbridgeUB8 3PH United Kingdom Department of Engineering University of Leicester LeicesterLE1 7RH United Kingdom Department of Engineering Viavi Solutions StevenageSG1 2AN United Kingdom Department Wireless Distribution Systems Fraunhofer Institute for Integrated Circuits IIS Fraunhofer-Gesellschaft Zur Foerderung der Angewandten Forschung E.V. Erlangen91058 Germany Research and Development Department Issy Média Issy-Les-Moulineaux92130 France Department of Electronic Engineering Research Institute of Information Technology Tsinghua National Laboratory of Information Science and Technology Tsinghua University Beijing100084 China

Many features of 5G are definitely important to the broadcasting service, including diverse content services such as follow-me TV, video-on-demand, but also gaming, Virtual reality (VR) and Augmented reality (AR) and many others. Meanwhile, those services depend more and more on the user's position accuracy, especially in indoor environment. With the increase of broadcasting data traffic indoors, to obtain a highly accurate position is becoming a challenge because of the impact of radio interference. In order to support a high-quality indoor broadcasting service, a high-accuracy positioning, radiation-free, and high-capacity communication system is urgently needed. In this paper, a 5G indoor positioning system is proposed for museums. It utilizes unlicensed visible light of the electromagnetic spectrum to provide museum visitors with high-accuracy positioning, multiple forms of interaction services, and high-resolution multimedia delivery on a mobile device. The geographic data and the location-related data integrated into the 5G New Radio (NR) waveform are detailed. A general-purpose system architecture is provided and some basic techniques to enhance system performance are also investigated. A preliminary demonstration is built in the laboratory environment. It supports over 45.25 Mbps data rate and a mean positioning error of 0.18 m. © 1963-12012 IEEE.

关键词： Location based services

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Nanofabricated and Integrated Colour Centres in Silicon Carbide with High-Coherence Spin-Optical Properties

Nanofabricated and Integrated Colour Centres in Silicon Carb...

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Frontiers in Optics + Laser Science 2021, FiO+LS 2021 - Part of Frontiers in Optics, FiO 2021

作者： Babin, Charles Stöhr, Rainer Morioka, Naoya Linkewitz, Tobias Steidl, Timo Wörnle, Raphael Liu, Di Vorobyov, Vadim Denisenko, Andrej Hentschel, Mario Gobert, Christian Berwian, Patrick Astakhov, Georgy Knolle, Wolfgang Majety, Sridhar Saha, Pranta Radulaski, Marina Son, Nguyen Tien Ul-Hassan, Jawad Kaiser, Florian Wrachtrup, Jörg 3rd Institute of Physics University of Stuttgart Institute for Quantum Science and Technology IQST Pfaffenwaldring 57 Stuttgart70569 Germany Institute for Chemical Research Kyoto University Kyoto Uji611-0011 Japan 4th Institute of Physics IQST Research Centre SCoPE University of Stuttgart Stuttgart70569 Germany Fraunhofer Institute for Integrated Systems and Device Technology IISB Schottkystr. 10 Erlangen91058 Germany Helmholtz-Zentrum Dresden-Rossendorf Institute of Ion Beam Physics and Materials Research Dresden01328 Germany Leipzig04318 Germany Department of Electrical and Computer Engineering University of California DavisCA95616 United States Department of Physics Chemistry and Biology Linköping University LinköpingSE-58183 Sweden

We demonstrate robust spin-optical properties of silicon vacancy centers in 4H-SiC after Helium-ion implantation and integration in nanophotonic-waveguides. For the latter, we show controlled operations on nuclear spi... 详细信息

ISBN: (纸本)9781557528209

关键词： Silicon carbide

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On the Systematic Construction of Lyapunov Functions for Polynomial systems

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PAMM 2023年第1期23卷

作者： Lars Natkowski Daniel Gerbet Klaus Röbenack Fraunhofer Institute for Transportation and Infrastructure Systems IVI Zeunerstraße 38 01069 Dresden Germany Institute of Control Theory Faculty of Electrical and Computer Engineering TU Dresden Georg-Schumann-Straße 7A 01187 Dresden Germany

Lyapunov functions are a widely used tool to evaluate stability properties of nonlinear dynamical systems' equilibria. In this paper quantifier elimination is used to construct Lyapunov functions for polynomial systems from a parametric ansatz. Because the existing algorithms for quantifier elimination are inherently computationally expensive, a strategy is to simplify the quantifier elimination problem beforehand. A method is presented that may help simplifying the problem of finding suitable Lyapunov functions by deriving easier to evaluate necessary conditions. Finally, the introduced method is applied to an example system to show local asymptotic stability of an equilibrium point by constructing a Lyapunov function.

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Hardware-in-the-loop test of learning-based controllers for grid-supportive building heating operation

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IFAC-PapersOnLine 2020年第2期53卷 17107-17112页

作者： Lilli Frison Sweetin Paul Torsten Koller David Fischer Gianluca Frison Joschka Boedecker Peter Engelmann Fraunhofer Institute for Solar Energy Systems ISE Freiburg Germany Neurorobotics Lab Dept. of Computer Science University of Freiburg Germany Dept. of Microsystems Engineering University of Freiburg Germany

While MPC is the state-of-the-art approach for building heating control with proven cost savings and improvement in energy flexibility, in practice, buildings are operated by simple rules-based controllers which are not able to accomplish an energy efficient and flexible operation. This paper explores the suitability of deep neural networks for approximating optimal economic MPC strategies for this task. In particular, we develop a convolutional neural network controller and test it in a closed-loop simulation against MPC and an improved predictive rule-based controller. The learned controller is easy to implement and fast to process on standard building control hardware. The feasibility, performance and robustness of the learned controller is validated in a realistic hardware-in-the-loop test setup for the demand-responsive operation of a heat pump combined with a storage tank.

关键词： Learning-based Control Neural Network Control Economic MPC Energy Storage Operation Planning Building Automation Smart Grids

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Fundamentals, materials, and machine learning of polymer electrolyte membrane fuel cell technology

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Energy and AI 2020年第1期1卷 187-218页

作者： Yun Wang Bongjin Seo Bowen Wang Nada Zamel Kui Jiao Xavier Cordobes Adroher Renewable Energy Resources Laboratory(RERL) Department of Mechanical and Aerospace EngineeringThe University of CaliforniaIrvineCA 92697-3975United States State key Laboratory of Engines Tianjin University135 Yaguan RoadTianjin 300350China Fraunhofer Institute for Solar Energy Systems ISE FreiburgGermanyHeidenhofstrasse 279110 General Motors Japan Ltd. Higashi-Shinagawa-kuTokyo140-8687Japan

Polymer electrolyte membrane(PEM)fuel cells are electrochemical devices that directly convert the chemical energy stored in fuel into electrical energy with a practical conversion efficiency as high as 65%.In the past years,significant progress has been made in PEM fuel cell *** 2019,there were over 19,000 fuel cell electric vehicles(FCEV)and 340 hydrogen refueling stations(HRF)in the U.S.(~8,000 and 44,respectively),Japan(~3,600 and 112,respectively),South Korea(~5,000 and 34,respectively),Europe(~2,500 and 140,respectively),and China(~110 and 12,respectively).Japan,South Korea,and China plan to build approximately 3,000 HRF stations by *** 2019,Hyundai Nexo and Toyota Mirai accounted for approximately 63%and 32%of the total sales,with a driving range of 380 and 312 miles and a mile per gallon(MPGe)of 65 and 67,*** of PEM fuel cells play a crucial role in the technological advancement to improve fuel cell performance/durability and reduce *** key aspects for fuel cell design,operational control,and material development,such as durability,electrocatalyst materials,water and thermal management,dynamic operation,and cold start,are briefly explained in this *** learning and artificial intelligence(AI)have received increasing attention in material/energy *** review also discusses their applications and potential in the development of fundamental knowledge and correlations,material selection and improvement,cell design and optimization,system control,power management,and monitoring of operation health for PEM fuel cells,along with main physics in PEM fuel cells for physics-informed machine *** objective of this review is three fold:(1)to present the most recent status of PEM fuel cell applications in the portable,stationary,and transportation sectors;(2)to describe the important fundamentals for the further advancement of fuel cell technology in terms of design and control optimization,cos

关键词： Pem Fuel cell Fundamental Material Machine learning Artificial intelligence Physics-informed

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Characterization of thin-film structures of silicon heterojunction solar cells with inline reflectance spectroscopy

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AIP Conference Proceedings 2023年第1期2826卷

作者： Saravana Kumar Henri Vahlman Sebastian Pingel Ioan Voicu Vulcanean Anamaria Steinmetz Jonas Haunschild Stefan Rupitsch Stefan Rein Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstr. 2 D-79110 Freiburg Germany Department of Microsystems Engineering University of Freiburg Georges-Köhler-Allee 106 D-79110 Freiburg Germany

In this work, we explore reflectance spectrophotometry as a fast, inline-compatible quality-assurance method to extract thin-film layer thicknesses on silicon heterojunction (SHJ) solar cell precursors. We develop an optical model based on the transfer-matrix method (TMM) and so-called rigorous polarization ray-tracing technique for the model-based fitting of experimental reflectance spectra. First, individual layers of both amorphous silicon (a-Si) and indium-doped tin-oxide (ITO) on planar surfaces are measured with both an inline and an offline spectrophotometer to compare the fit results and to understand the quality of the optical constants that are necessary as input parameters to perform the model-based fitting. We find that using effective optical constants based on spectral ellipsometry (SE) results in reliable fitted a-Si stack and ITO thicknesses in the case of individual layers on planar surfaces. Second, we analyze single layers of ITO on a textured surface, finding a reasonable agreement with a mean relative deviation of 5% between the thickness values based on inline and offline reflectance spectra. We also compare the results of the reflectance fits to thicknesses extracted from scanning electron microscopy (SEM) images, finding a mean relative deviation of 10.7% between the two methods. Third, we perform a reflectance analysis of a-Si/ITO stacks on textured surfaces typical for SHJ solar cells and find that while the ITO thickness can be fitted to an accuracy of 4% in mean relative deviation compared to SEM images, the a-Si stack thicknesses are overestimated by 18–51% compared to reference measurements based on SE. Subsequently, we discuss the reasons for the deviations between the model-based reflectance fitting and the reference methods, and consider possibilities to improve the agreement.

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Two-fluid mobility model from coupled hydrodynamic equations for simulating laser-driven semiconductor switches

arXiv

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arXiv 2025年

作者： Wu, Qile Sojka, Antonín Price, Brad D. Agladze, Nikolay I. Yadav, Anup Pain, Sophie L. Murphy, John D. Niewelt, Tim Sherwin, Mark S. Physics Department University of California Santa BarbaraCA93106 United States Institute for Terahertz Science and Technology University of California Santa BarbaraCA93106 United States School of Engineering University of Warwick CoventryCV4 7AL United Kingdom Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstraße 2 Freiburg79110 Germany Department of Sustainable Systems Engineering University of Freiburg Emmy-Noether-Straße 2 Freiburg79110 Germany

We introduce a two-fluid mobility model incorporating fundamental aspects of electron-hole (eh) scattering such as momentum conservation for simulating laser-driven semiconductor switches (LDSSs). Compared to previous works that use Matthiessen’s rule, the two-fluid mobility model predicts distinct AC responses of e-h plasmas in semiconductors. Based on the two-fluid mobility model, we develop a theory with very few adjustable parameters for simulating the switching performance of LDSSs based on high-purity indirect-gap semiconductors such as silicon (Si). As a prototypical application, we successfully reproduce experimentally measured reflectance at around 320 GHz in a laser-driven Si switch. By injecting e-h plasmas with densities up to 1020 cm−3, we reveal the importance of carrier-screening effects in e-h scattering and Auger recombination for carrier densities above the critical carrier density for exciton-plasma Mott transition. Our results also suggest a way to characterize the intrinsic momentum-relaxation mechanism, e-h scattering, and the intrinsic e-h recombination mechanism in indirect-gap semiconductors, Auger recombination. We reassess the ambipolar Auger coefficient of high-purity Si with high injection levels of e-h plasmas up to 1020 cm−3 and find a minimal value of 1.8 × 10−41 cm6/ns. The value is more than one order of magnitude smaller than the ambipolar Auger coefficient widely used for simulating LDSSs, 3.8 × 10−40 cm6/ns, which was deduced from minority-carrier lifetime in highly doped silicon more than four decades ago. Copyright © 2025, The Authors. All rights reserved.

关键词： Injection lasers

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