Person

Stephan Neumann

M. Eng.

Head of Off-Highway

Picture of Stephan Neumann
Chair and Institute for Machine Elements and Systems Engineering

Address

Building: 1310

Room: 403

Schinkelstr. 10

52062 Aachen

Contact

WorkPhone
Phone: +49 241 80 90853
Fax Fax: +49 241 80 92256

Office Hours

n. Übereink.
 

Vita

Stephan Neumann, M.Eng. completed an apprenticeship as industrial mechanic and a further education as Master craftsman for car technology. From 2006 to 2011 he studied mechanical engineering with a specialization in "Design Technology and Renewable Energies" at the Beuth University of Applied Sciences Berlin. Beside his studies, he worked several years as a research assistant at the Fraunhofer Institute for Production Systems and Design Technology in the division of Virtual Product Creation. He completed his studies with a Master thesis at Fraunhofer IPK about maintenance oriented, three dimensional and condition based product models.

From 2011, Mr. Neumann worked as a research engineer at MSE (former IME) in the Off-Highway department. In his personal research, he focuses on the functionalization of surfaces using micro-structures. In 2014 he became head of the research group system-test.

From 2016 to 2019 Mr. Neumann worked at the "Chair for Wind Power Drives". There he led the WT-Bearing Center.NRW project.

In November 2019 Mr. Neumann became the head of the Off-Highway department.

 

Publications

Source Author(s)
[Journal Article]
Effect of Electrification on the Quantitative Reliability of an Offshore Crane Winch in Terms of Drive-Induced Torque Ripples
In: Modeling, identification and control : MIC, 44 (1), 1-16, 2023
[DOI: 10.4173/mic.2023.1.1]
Yousri, Mohamed (Corresponding author)
Jacobs, Georg (Corresponding author)
Neumann, Stephan (Corresponding author)
[Contribution to a book, Contribution to a conference proceedings]
Evaluating the Communication Infrastructure of a Digital Process Platform for Future Construction Sites
In: 2022 2nd International Conference on Computing and Machine Intelligence (ICMI) : [Proceedings], 1-6, 2022
[DOI: 10.1109/ICMI55296.2022.9873671]
Gannouni, Aymen (Corresponding author)
Otte, Thomas (Corresponding author)
Zhou, Hans Aoyang (Corresponding author)
Hosan, Arif (Corresponding author)
Odenthal, Jonas (Corresponding author)
et al.
[Contribution to a book, Journal Article]
Optimization Workflows for Linking Model-Based Systems Engineering (MBSE) and Multidisciplinary Analysis and Optimization (MDAO)
In: Applied Sciences, 12 (11), 5316, 2022
[DOI: 10.3390/app12115316]
Habermehl, Christian (Corresponding author)
Höpfner, Gregor
Berroth, Joerg Karl
Neumann, Stephan
Jacobs, Georg
[Contribution to a book, Contribution to a conference proceedings]
Towards a data-driven assistance system for operating segment erectors in tunnel boring machines
In: 2021 14th International Symposium on Computational Intelligence and Design (ISCID) : Proceedings. - 11-12 December 2021 Hangzhou, China, 263-267, 2021
[DOI: 10.1109/ISCID52796.2021.00068]
Zhou, Hans Aoyang (Corresponding author)
Gannouni, Aymen
Gentz, Christian Robert Maria
Trondle, Johannes
Neumann, Stephan
et al.
[Contribution to a book]
Daten von Land- und Baumaschinen gewinnbringend nutzen : Analyse derzeitiger Monetarisierungsmechanismen und Handlungsempfehlungen für die Zukunft
In: Monetarisierung von technischen Daten: Innovationen aus Industrie und Forschung / Daniel Trauth, Thomas Bergs, Wolfgang Prinz (Hrsg.), 471-520, 2021
[DOI: 10.1007/978-3-662-62915-4_25]
Lehmann, Benjamin Felix (Corresponding author)
Jacobs, Georg
Habermehl, Christian
Gentz, Christian Robert Maria
Neumann, Stephan
[Contribution to a book, Contribution to a conference proceedings]
Damage Diagnosis of Cardan Shafts in Mobile Mining Machines using Vibration Analysis
In: 19th Drive Train Technology Conference (ATK 2021) 9th-11th March 2021, Aachen, Germany, 012019, 1-12, 2021
[DOI: 10.1088/1757-899X/1097/1/012019]
Golafshan, Reza (Corresponding author)
Dascaliuc, Catalin
Jacobs, Georg
Roth, David Johannes
Berroth, Joerg Karl
et al.
[Contribution to a book, Contribution to a conference proceedings]
Optimization-based Component Sizing Method for Electrified Heavy-Duty Powertrain Concepts
In: 19th Drive Train Technology Conference (ATK 2021) : 9th-11th March 2021, Aachen, Germany / editorial board: Prof. Dr.-Ing. Georg Jacobs, Sebastian Stein, M.Sc, 012002, 1-15, 2021
[DOI: 10.1088/1757-899X/1097/1/012002]
Roth, David Johannes (Corresponding author)
Habermehl, Christian
Jacobs, Georg
Neumann, Stephan
Juretzki, Björn
et al.
[Journal Article]
Condition monitoring of roller bearings using acoustic emission
In: Wind energy science : WES, 6 (2), 367-376, 2021
[DOI: 10.5194/wes-6-367-2021]
Cornel, Daniel (Corresponding author)
Gutiérrez Guzmán, Francisco Gerardo Antonio
Jacobs, Georg
Neumann, Stephan
[Journal Article]
Impact of fiber versus steel ropes on the lifetime of crane winches
In: Modeling, identification and control : MIC, 41 (3), 129-139, 2020
[DOI: 10.4173/mic.2020.3.1]
Mohamed, Yousri (Corresponding author)
Jacobs, Georg (Corresponding author)
Neumann, Stephan (Corresponding author)
[Contribution to a book, Journal Article]
Influence of Drivetrain Hybridization on Transmission Lifetime
In: Applied Sciences, 10 (20), 7086, 2020
[DOI: 10.3390/app10207086]
Habermehl, Christian (Corresponding author)
Jacobs, Georg
Neumann, Stephan
Weißenfels, Kevin
[Report]
Schlussbericht DUETT - Diesel-Hybridfahrzeuge für eine umweltbewusste Mobilität: Eine vernetzte Systementwicklung in physischer und virtueller Umgebung, 2020
Habermehl, Christian
Jacobs, Georg
Neumann, Stephan
[Journal Article]
A modeling method for gear transmission efficiency in transient operating conditions
In: Mechanism and machine theory, 153, 103996, 2020
[DOI: 10.1016/j.mechmachtheory.2020.103996]
Habermehl, Christian (Corresponding author)
Jacobs, Georg
Neumann, Stephan
[Journal Article]
Availability Increase of Mobile Machinery through Condition Prognosis
In: ATZ heavyduty worldwide, 13 (2), 62-67, 2020
[DOI: 10.1007/s41321-020-0081-z]
Habermehl, Christian (Corresponding author)
Jacobs, Georg (Corresponding author)
Neumann, Stephan
Lehmann, Benjamin Felix
[Journal Article]
Verfügbarkeitssteigerung mobiler Arbeitsmaschinen durch Zustandsprognose
In: ATZheavy duty, 13 (2), 64-68, 2020
[DOI: 10.1007/s35746-020-0080-0]
Habermehl, Christian (Corresponding author)
Jacobs, Georg
Neumann, Stephan
Lehmann, Benjamin Felix
[Journal Article]
Reliability assessment of repairable phased-mission system by Monte Carlo simulation based on modular sequence-enforcing fault tree model
In: Eksploatacja i niezawodność = Maintenance and reliability, 22 (2), 272-281, 2020
[DOI: 10.17531/ein.2020.2.10]
Liu, Chenxi (Corresponding author)
Kramer, Achim (Corresponding author)
Neumann, Stephan (Corresponding author)
[Report]
Schlussbericht ProMaschinenDaten - Verfügbarkeitssteigerung mobiler Arbeitsmaschinen durch Prognose des Maschinenzustands auf Basis globaler Daten, 2020
Roth, David Johannes
Jacobs, Georg
Habermehl, Christian
Golafshan, Reza
Keller, Dennis
et al.
[Report]
Schlussbericht: Dezentrale kompakte Hydraulikversorgung durch High-Speed-Komponenten, 2020
Roth, David Johannes
Pietrzyk, Tobias
Jacobs, Georg
Schmitz, Katharina
Neumann, Stephan
[Contribution to a book, Journal Article]
Development of a Low-Friction Radial Shaft Seal : Using CFD Simulations to Optimise the Microstructured Sealing Lip
In: Lubricants : open access journal, 8 (4), 41, 2020
[DOI: 10.3390/lubricants8040041]
Keller, Dennis (Corresponding author)
Jacobs, Georg
Neumann, Stephan
[Report]
Entwicklung einer Prüfmethode zur Bewertung der Energieeffizienz von Radladern : Schlussbericht zum IGF-Vorhaben Nr. 19088N1 : Berichtszeitraum 01.01.2017 - 31.07.2019 : Forschungsvereinigung: Forschungskuratorium Maschinenbau e.V., Lyoner Straße 18, 60528 Frankfurt/Main, Forschungseinrichtung(en): Institut für Maschinenelemente und Systementwicklung, Schinkelstraße 10, 52062 Aachen, 2020
Gentz, Christian Robert Maria
Jacobs, Georg
Neumann, Stephan
[Contribution to a book, Contribution to a conference proceedings]
Acoustic response of roller bearings under critical operating conditions
In: Engineering assets and public infrastructures in the age of digitalization : proceedings of the 13th World Congress on Engineering Asset Management / Jayantha P. Liyanage, Joe Amadi-Echendu, Joseph Mathew, editors, 740-749, 2020
[DOI: 10.1007/978-3-030-48021-9_82]
Cornel, Daniel (Corresponding author)
Gutierrez Guzman, Francisco Gerardo Antonio
Jacobs, Georg
Neumann, Stephan
[Journal Article]
Load analysis of special operation conditions and implementation of derived load states in Bearing Robustness Test (BRT)
In: Journal of physics / Conference series, 1222, 012021, 2019
[DOI: 10.1088/1742-6596/1222/1/012021]
Hirt, Andreas (Corresponding author)
Jacobs, Georg
Neumann, Stephan
Kock, Stefan
Bosse, Dennis
[Journal Article]
Die Reibung dynamischer Elastomerdichtungen reduzieren : Simulationsgestützte Optimierung der mikrostrukturierten Dichtfläche
In: Jahrbuch ... Dichten, Kleben, Polymer, 2020, 154-170, 2019
Keller, Dennis
Jacobs, Georg
Kramer, Achim
Neumann, Stephan
[Contribution to a book, Contribution to a conference proceedings]
Robustheitstest für Getriebewälzlagerungen in Windenergieanlagen
In: 13. VDI-Fachtagung Gleit- und Wälzlagerungen 2019 : Schweinfurt, 05.-06. Juni 2019 / VDI Produkt- und Prozessgestaltung, 233-244, 2019
[DOI: 10.18154/RWTH-2019-08170]
Oberdörfer, Sergej
Jacobs, Georg
Neumann, Stephan
[Contribution to a book, Contribution to a conference proceedings]
Determination of a Load Spectrum for a Robustness Test of WT Gearbox-Bearings
In: Conference for Wind Power Drives, CWD 2019 : Aachen 12th-13th of March : conference proceedings, Aachen, 12th-13th of March 2019 / Dirk Abel, Christian Brecher, Rik W. De Doncker, Kay Hameyer, Georg Jacobs, Antonello Monti, Wolfgang Schröder, Andreas Hirt, 2019
[DOI: 10.18154/RWTH-2019-04789]
Oberdörfer, Sergej
Jacobs, Georg
Kock, Stefan
Neumann, Stephan
Bosse, Dennis
[Contribution to a book, Contribution to a conference proceedings]
Test method for local load analysis of planetary bearings
In: Conference for Wind Power Drives, CWD 2019 : Aachen 12th-13th of March : conference proceedings, Aachen, 12th-13th of March 2019 / Dirk Abel, Christian Brecher, Rik W. De Doncker, Kay Hameyer, Georg Jacobs, Antonello Monti, Wolfgang Schröder, Andreas Hirt, 2019
[DOI: 10.18154/RWTH-2019-03710]
Kock, Stefan
Jacobs, Georg
Neumann, Stephan
Bosse, Dennis
Sedlatschek, Tobias
[Contribution to a book, Contribution to a conference proceedings]
Friction Reduction of dynamic Elastomer Seals by Microstructuring of the Seal Sliding Surface
In: Zylinderlaufbahn, Kolben, Pleuel 2018 : der Kurbeltrieb im Spannungsfeld unterschiedlicher Anforderungen : Baden Baden, 05. und 06. Juni 2018. VDI-Fachtagung / VDI-Gesellschaft Materials Engineering, 137-152, 2018
Keller, Dennis
Jacobs, Georg
Kramer, Achim
Neumann, Stephan
Paulkowski, D.
et al.
[Contribution to a book, Contribution to a conference proceedings]
Reibungsreduzierung dynamischer Elastomerdichtungen durch die simulationsgestützte Optimierung der mikrostrukturierten Dichtfläche
In: Sealing technology - beyond limitations : International Sealing Conference : 20th ISC : Stuttgart, Germany, Oct. 10-11, 2018 / eine Kooperation von IMA Uni Stuttgart, VDMA Fluidtechnik, 2018
Keller, Dennis
Jacobs, Georg
Kramer, Achim
Neumann, Stephan
[Conference Presentation]
Analysis of main influencing factors on critical loads at transmission bearings and identification of critical operation states
In: Wind Turbine Bearings 2018 Hamburg 2018-05-29 - 2018-05-31, 2018
[DOI: 10.18154/RWTH-2018-225887]
Hirt, Andreas (Corresponding author)
Jacobs, Georg
Neumann, Stephan
Bosse, Dennis
[Conference Presentation]
Robustness Test for Wind Turbine Gearbox Bearings
In: 7. International Conference The Science of Making Torque from Wind Milan 2018-06-20 - 2018-06-22, 2018
Kock, Stefan
Jacobs, Georg
Hirt, Andreas
Oberdörfer, Sergej
Neumann, Stephan
et al.
[Contribution to a conference proceedings, Journal Article]
Robustness Test for Wind Turbine Gearbox Bearings
In: Journal of physics / Conference Series, 1037, 052012, 2018
[DOI: 10.1088/1742-6596/1037/5/052012]
Kock, Stefan (Corresponding author)
Jacobs, Georg
Hirt, Andreas
Oberdörfer, Sergej
Neumann, Stephan
et al.
[Conference Presentation]
Reibungsreduzierung dynamischer Elastomerdichtungen durch Mikrostrukturierung der Dichtungsgleitfläche
In: 9. VDI-Fachtagung "Zylinderlaufbahn, Kolben, Pleuel 2018" Baden-Baden 2018-06-05 - 2018-06-06, 2018
Keller, Dennis
Jacobs, Georg
Kramer, Achim
Neumann, Stephan
Paulkowski, Dominik
et al.
[Contribution to a book, Contribution to a conference proceedings]
Reibungsreduzierung dynamischer Elastomerdichtungen durch Mikrostrukturierung der Dichtungsgleitfläche
In: Zylinderlaufbahn, Kolben, Pleuel 2018 : der Kurbeltrieb im Spannungsfeld unterschiedlicher Anforderungen : Baden Baden, 05. und 06. Juni 2018. VDI-Fachtagung / VDI-Gesellschaft Materials Engineering, 137-153, 2018
Keller, Dennis
Jacobs, Georg
Kramer, Achim
Neumann, Stephan
Paulkowski, Dominik
et al.
[Contribution to a conference proceedings]
A sensitivity analysis of planetary- and high speed shaft bearing loads for typical operating conditions of wind turbines
In: [Wind Europe Conference & Exhibition, 2017-11-28 - 2017-11-30, Amsterdam, Netherlands], 2017
[DOI: 10.18154/RWTH-2018-221577]
Hirt, Andreas (Corresponding author)
Jacobs, Georg
Neumann, Stephan
Bosse, Dennis
[Poster]
A Sensitivity analysis of planetary- and high speed shaft bearing loads in wind turbines
In: Wind Europe Conference and Exhibition Amsterdam 2017-11-28 - 2017-11-30, 2017
[DOI: 10.18154/RWTH-2018-221576]
Hirt, Andreas
Jacobs, Georg
Neumann, Stephan
Bosse, Dennis
[Contribution to a book]
Reliability Evaluation of Drivetrains : Challenges for Off‐Highway Machines
In: System Reliability / edited by Constantin Volosencu, 147-164, 2017
[DOI: 10.5772/intechopen.70280]
Wöll, Lothar Christof (Corresponding author)
Schick, Katharina
Jacobs, Georg
Kramer, Achim
Neumann, Stephan
[Contribution to a conference proceedings]
Reibungsreduktion dynamischer Elastomerdichtungen durch Lasermikrostrukturierung und plasmapolymere Beschichtung
In: [6. ATZ-Fachtagung Tribologie "Reibungsminimierung im Antriebsstrang"], 2017
[DOI: 10.18154/RWTH-2017-10646]
Keller, Dennis (Corresponding author)
Jacobs, Georg (Corresponding author)
Kramer, Achim (Corresponding author)
Neumann, Stephan (Corresponding author)
Paulkowski, Dominik (Corresponding author)
et al.
[Journal Article]
Reduzierung von Lagerschäden im Antriebsstrang von Windenergieanlagen : WEA-Lagerzentrum.NRW
In: Ingenieur-Spiegel : Fachmagazin für Ingenieure / [Hellblaue Ausgabe], 2017 (4), 7-11, 2017
[DOI: 10.18154/RWTH-2017-09861]
Neumann, Stephan
Jacobs, Georg
[Journal Article]
Determination of Hydraulic Losses in Radial Cylindrical Roller Bearings Using CFD Simulations
In: Tribology international, 113, 507-509, 2017
[DOI: 10.1016/j.triboint.2017.05.015]
Feldermann, Achim
Fischer, Dennis
Neumann, Stephan
Jacobs, Georg
[Contribution to a conference proceedings, Journal Article]
Determination of hydraulic losses in radial cylindrical roller bearings using CFD simulations
In: Tribology international, 113, 245-251, 2017
[DOI: 10.1016/j.triboint.2017.03.020]
Feldermann, Achim
Fischer, Dennis (Corresponding author)
Neumann, Stephan
Jacobs, Georg
[Contribution to a book, Contribution to a conference proceedings]
Comprehensive reliability model of a passenger car gearbox
In: Antriebstechnisches Kolloquium : ATK 2017 : Aachen 07.-08. März : Tagungsband, Aachen 07.-08. März / herausgegeben von Univ.-Prof. Dr.-Ing. Georg Jacobs (Institut für Maschinenelemente und Maschinengestaltung) ; IME, Institut für Maschinenelemente und Maschinengestaltung, RWTH Aachen University ; Editor: Felix M. Schlüter, 387-403, 2017
Kamper, Tim (Corresponding author)
Hwang, Dong-Hwan
Juretzki, Björn
Neumann, Stephan
Wöll, Lothar Christof
[Contribution to a book, Contribution to a conference proceedings]
Einfluss der Wellenhöhe auf die Zuverlässigkeit einer Offshore-Winde
In: Antriebstechnisches Kolloquium ATK 2017 : Aachen 07.-08.März : Tagungsband : Aachen, 07.-08. März 2017 / herausgegeben von Univ.-Prof. Dr.-Ing. Georg Jacobs (Institut für Maschinenelemente und Maschinengestaltung) ; Institut für Maschinenelemente und Maschinengestaltung, RWTH Aachen University, 57-70, 2017
Wöll, Lothar Christof
Jacobs, Georg
Feldermann, Achim
Neumann, Stephan
Straßburger, Felix
[Journal Article]
CFD simulation of elastohydrodynamic lubrication problems with reduced order models for fluid-structure interaction
In: Tribology : materials, surfaces & interfaces, 11 (1), 30-38, 2017
[DOI: 10.1080/17515831.2017.1279846]
Feldermann, Achim (Corresponding author)
Neumann, Stephan
Jacobs, Georg
[Contribution to a book]
Reibungs- und Leckagereduzierung bei dynamischen Kontaktdichtungen
In: Technik Jahrbuch 2016 Industriearmaturen Dichtungen / Editor: Wolfgang Mönning, 153-157, 2016
Neumann, Stephan
Jacobs, Georg
Straßburger, Felix
[Journal Article]
Modular System Modeling for Quantitative Reliability Evaluation of Technical Systems
In: Modeling, identification and control : MIC, 37 (1), 19-29, 2016
[DOI: 10.4173/mic.2016.1.2]
Neumann, Stephan (Corresponding author)
Wöll, Lothar Christof
Feldermann, Achim
Straßburger, Felix
Jacobs, Georg
[Conference Presentation]
Reducing Friction and Leakage by Means of Microstructured Sealing Surfaces - Example Mechanical Face Seal
In: 10. International Fluid Power Conference Dresden 2016-03-08 - 2016-03-10, 2016
Wolking, Sebastian
Neumann, Stephan (Corresponding author)
Jacobs, Georg
Feldermann, Achim
Straßburger, Felix
[Contribution to a conference proceedings]
Reducing Friction and Leakage by Means of Microstructured Sealing Surfaces - Example Mechanical Face Seal
In: [10th International Fluid Power Conference, 10. IFK, 08.03.2016-10.03.2016, Dresden, Germany], 493-506, 2016
Neumann, Stephan (Corresponding author)
Jacobs, Georg
Feldermann, Achim
Straßburger, Felix
[Contribution to a book, Contribution to a conference proceedings]
CFD Modeling of Elastohydrodynamic Lubrication Using Reduced FE-Models
In: [European Conference on Tribology 2015, Ecotrib 2015, 2015-06-03 - 2015-06-05, Lugano, Switzerland], 3-3, 2015
Feldermann, Achim (Corresponding author)
Neumann, Stephan
Jacobs, Georg
[Conference Presentation]
CFD Modeling of Elastohydrodynamic Lubrication with Reduced Order Models for Fluid-Structure Interaction
In: 1. International Conference on Tribology Turkeytrib Istanbul 2015-10-07 - 2015-10-09, 2015
Feldermann, Achim (Corresponding author)
Neumann, Stephan
Jacobs, Georg
[Contribution to a conference proceedings, Journal Article]
CFD Modelling of Elastohydrodynamic Lubrication Using High-Pressure Rheology Models
In: Tribological Journal BULTRIB, 5, 2015
Feldermann, Achim (Corresponding author)
Neumann, Stephan
Jacobs, Georg
[Conference Presentation]
CFD Modeling of Elastohydrodynamic Lubrication Using Reduced FE-Models
In: European Conference on Tribology Lugano 2015-06-03 - 2015-06-05, 2015
Feldermann, Achim (Corresponding author)
Neumann, Stephan
Jacobs, Georg
[Contribution to a book, Journal Article]
Funktionalisierung der Gleitflächen von Laufwerkdichtungen
In: Dichtungstechnik Jahrbuch, 2016, 260-274, 2015
Neumann, Stephan (Corresponding author)
Feldermann, Achim
Straßburger, Felix
Jacobs, Georg
[Journal Article]
Reibungs- und Leckagereduzierung bei dynamischen Kontaktdichtungen
In: Dichtungstechnik, 18 (2), 34-38, 2015
Neumann, Stephan (Corresponding author)
Straßburger, Felix
Jacobs, Georg
[Contribution to a book, Contribution to a conference proceedings]
Funktionalisierung der Gleitflächen von Gleitringdichtungen durch Mikrostrukturen zur Reduzierung von Reibung und Leckage
In: [Schadensfälle und ihre Vermeidung Vorträge des XIX. Dichtungskolloquiums am 23./24.09.2015 / Herausgeber: Alexander Riedl], 188-204, 2015
[DOI: 10.18154/RWTH-2015-05325]
Neumann, Stephan (Corresponding author)
Jacobs, Georg
Feldermann, Achim
Straßburger, Felix
[Journal Article]
Laufwerkdichtungen werden leistungsfähiger : Die Funktionalisierung der Gleitflächen von Gleitringdichtungen macht durch neue Verfahren Fortschritte
In: Dicht! : Trialog der Dichtungs- und Klebetechnik, 9 (1), 14-15, 2015
Neumann, Stephan (Corresponding author)
Jacobs, Georg
Armbrüster, Stefan
Eifel, Stephan
[Contribution to a book, Contribution to a conference proceedings]
Simulation einer mikrostrukturierten Laufwerkdichtung als flexibles Mehrkörpersystem mit Kopplung zur Elastohydrodynamik
In: Sealing technology - hidden high tech : 18th ISC, International Sealing Conference ; Stuttgart, Germany, October 08 - 09, 2014 : 18th ISC, Internationale Dichtungstagung / Fluidtechnik; IMA Uni Stuttgart, 482-503, 2014
Neumann, Stephan
Straßburger, Felix
Jacobs, Georg