Publikationen

2021

• An analysis of top author citations in software engineering and a comparison with other fields

  Petersen, K. ., & Bin Ali, N. . (2021). An analysis of top author citations in software engineering and a comparison with other fields. Scientometrics, 126, 9147–9183.

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    • Petersen, Kai

  • Abteilung/Einrichtung

    • FLAIR - Flensburg Artificial Intelligence Research

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  • 2021
  • Journal Article
  • • Kai Petersen
    • Nauman Bin Ali

• Financial performance and firm efficiency of automotive manufacturers and their suppliers A longitudinal data envelopment analysis

  Brandenburg, M. ., & Hahn, G. J. (2021). Financial performance and firm efficiency of automotive manufacturers and their suppliers A longitudinal data envelopment analysis. Logistics Research, 14(1), 26. http://doi.org/10.23773/2021_01

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  A data envelopment analysis (DEA) is presented to assess evolutions of firm efficiency and financial performance in automotive supply chains. A sample of 32 decision-making units (DMUs), 17 globally operating original equipment manufacturers (OEMs) and 15 key suppliers from the automotive industry, is in focus of this analysis in which cost levels and capital requirements are put into relation to sales growth and profit. Cost of goods sold, operating capital, and net fixed assets represent the financial input of a company while sales growth and earnings before interest and taxes (EBIT) reflect the financial output. The financial performance of a firm is indicated by its efficiency, calculated by an input-oriented variable returns to scale model. A multiple linear regression analysis reveals which operational performance factors are predictors of financial performance. A longitudinal DEA approach that covers the years from 2003 to 2017 is chosen to reveal performance evolutions over time. In order to analyze the stability of relationships between efficient firms (peers) and inefficient ones (followers) over time, changes in the performance relationship network are assessed in a graph-theoretic approach. In this study, geographical and structural specifics of DMU groups are taken into account. The study reveals similarities and differences between OEMs and their suppliers regarding the importance of value drivers and detects periods of performance losses and recovery from the global economic crisis.

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    • Brandenburg, Marcus

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  • 2021
  • Journal Article
  • • Marcus Brandenburg
    • Gerd Hahn
  • • Automotive industry
    • Data Envelopment Analysis
    • Financial performance
    • Supply networks

• Subsurface renewable energy storage capacity for hydrogen, methane and compressed air – A performance assessment study from the North German Basin

  Gasanzade, F. ., Pfeiffer, W. T., Witte, F. ., Tuschy, I. ., & Bauer, S. . (2021). Subsurface renewable energy storage capacity for hydrogen, methane and compressed air – A performance assessment study from the North German Basin. Renewable and Sustainable Energy Reviews, 149, 111422. http://doi.org/https://doi.org/10.1016/j.rser.2021.111422

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  The transition to renewable energy sources to mitigate climate change will require large-scale energy storage to dampen the fluctuating availability of renewable sources and to ensure a stable energy supply. Energy storage in the geological subsurface can provide capacity and support the cycle times required. This study investigates hydrogen storage, methane storage and compressed air energy storage in subsurface porous formations and quantifies potential storage capacities as well as storage rates on a site-specific basis. For part of the North German Basin, used as the study area, potential storage sites are identified, employing a newly developed structural geological model. Energy storage capacities estimated from a volume-based approach are 6510 TWh and 24,544 TWh for hydrogen and methane, respectively. For a consistent comparison of storage capacities including compressed air energy storage, the stored exergy is calculated as 6735 TWh, 25,795 TWh and 358 TWh for hydrogen, methane and compressed air energy storage, respectively. Evaluation of storage deliverability indicates that high deliverability rates are found mainly in two of the three storage formations considered. Even accounting for the uncertainty in geological parameters, the storage potential for the three considered storage technologies is significantly larger than the predicted demand, and suitable storage rates are achievable in all storage formations.

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    • Witte, Francesco
    • Tuschy, Ilja

  • Profilbereich

    • Erneuerbare Energien und nachhaltige Entwicklung

  • Forschungsfeld

    • Wärme
    • Netzintegration

  • Fachbereich

    • Fachbereich 2: Energy and Life Science

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  • 2021
  • Journal Article
  • • Firdovsi Gasanzade
    • Wolf Pfeiffer
    • Francesco Witte
    • Ilja Tuschy
    • Sebastian Bauer
  • • Subsurface energy storage
    • Storage capacity
    • Exergy assessment
    • North German Basin
    • Geological porous media
    • Compressed air energy storage
    • Hydrogen gas storage
    • Methane gas storage
    • Achievable storage rate

• Connectivity is key: holistic sustainability assessment and reporting from the perspective of food manufacturers

  Küchler, R. ., & Herzig, C. . (2021). Connectivity is key: holistic sustainability assessment and reporting from the perspective of food manufacturers. British Food Journal. http://doi.org/10.1108/BFJ-03-2021-0317

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  As members of the food supply chain, food manufacturers acquire power and hold responsibility for the sustainable transformation of our food systems. Sustainability assessment and reporting frameworks function as instruments to shape sustainable transformation processes. Their suitability for food manufacturing companies and their connectivity with the up- and downstream food supply chain is investigated here. The first section of the study explores the need for holistic, company-based sustainability frameworks in the food manufacturing sector from the literature. The second part compares seven frameworks, in terms of content and supply chain connectivity. Food sector specificity demands the inclusion of topics specific to food systems. Furthermore, none of the investigated frameworks fulfils both food sector specificity and full connectivity with the up- and downstream supply chain. As a limitation to this work, comparison of the frameworks at topic-level instead of indicator-level is considered. The findings call for more harmonised and integrated sustainability assessment throughout the food supply chain. The framework a food manufacturer should apply depends on their motivation behind conducting the sustainability assessment and reporting. Evidence is provided from various perspectives and with regard to key issues such as content, certification and communication. No comparison between sustainability frameworks has been made yet from the supply chain perspective of food manufacturers.

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    • Fachbereich 2: Energy and Life Science

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  • 2021
  • Journal Article
  • • Rebekka Küchler
    • Christian Herzig

• Capturing shrinkage and neck growth with phase field simulations of the solid state sintering.

  Ivannikov, V. ., Thomsen, F. ., Ebel, T. ., & Willumeit-Römer, R. . (2021). Capturing shrinkage and neck growth with phase field simulations of the solid state sintering. Modelling and Simulation in Materials Science and Engineering, 29(7). http://doi.org/10.1088/1361-651X/ac1f87

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    • Thomsen, Fritz

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  • 2021
  • Journal Article
  • • Vladimir Ivannikov
    • Fritz Thomsen
    • Thomas Ebel
    • Regine Willumeit-Römer

• Grid Services and Stress Reduction with a Flywheel in the Rotor of a Wind Turbine

  Jauch, C. . (2021). Grid Services and Stress Reduction with a Flywheel in the Rotor of a Wind Turbine. Energies, 14. http://doi.org/10.3390/en14092556

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  Wind power penetration increases in most grids and the sizes of wind turbines increase. This leads to increasingly tough requirements, which are imposed on wind turbines, both from the grid as well as from economics. Some of these partially contradictory requirements can only be satisfied with additional control mechanisms in the wind turbines. In this paper, such a mechanism, i.e., a hydraulic–pneumatic flywheel system in the rotor of a wind turbine, is discussed. This flywheel system supports a wind turbine in providing grid services such as steadying the power infeed, fast frequency response, continuous inertia provision, power system stabilization, and low voltage ride-through. In addition, it can help mitigate the stress on the mechanical structure of a wind turbine, which results from varying operating points, imbalances in the rotor, gravitation that acts on the blades, in-plane vibrations, and emergency braking. The study presented in this paper is based on simulations of a publicly available reference wind turbine. Both the rotor blade design as well as the design of the flywheel system are as previously published. It is discussed how the aforementioned grid services and the stress reduction mechanisms can be combined. Finally, it is concluded that such a flywheel system broadens the range of control mechanisms of a wind turbine substantially, which is beneficial for the grid as well as for the wind turbine itself.

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    • Jauch, Clemens

  • Fachbereich

    • Fachbereich 2: Energy and Life Science

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  • 2021
  • Journal Article
  • • Prof. Dr. Clemens Jauch

• Implementation of Variable Blade Inertia in OpenFAST to Integrate a Flywheel System in the Rotor of a Wind Turbine

  Alhrshy, L. . (2021). Implementation of Variable Blade Inertia in OpenFAST to Integrate a Flywheel System in the Rotor of a Wind Turbine. Energies, 14. http://doi.org/10.3390/en14102783

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  In this paper, the integration of the dynamic behavior of the flywheel system into the load simulation tool OpenFAST is presented. The flywheel system enables a wind turbine to vary the inertia of its rotor blades to control the power production and, most importantly, to affect the vibratory behavior of wind turbine components. Consequently, in order to simulate the behavior of a wind turbine with a flywheel system in its rotor, the variable blade characteristics need to be considered in the load simulation tool. Currently, computer-aided engineering tools for simulating the mechanical loads of wind turbines are not designed to simulate variable blade inertia. Hence, the goal of this paper is to explain how variable inertias of rotor blades are implanted in such load simulation tools as OpenFAST. OpenFAST is used because of it is free, publicly available, and well documentation. Moreover, OpenFAST is open source, which allows modifications in its source code. This add-on in the load simulation is applied to correct rotor mass imbalance. It can also be applied in many cases related to the change in the inertia of wind turbine rotor blades during its operation as, for example, atmospheric ice accretion on the blades, smart blades, etc.

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    • Alhrshy, Laurence

  • Forschungsprojekt

    • Schwungrad

  • Abteilung/Einrichtung

    • Wind Energy Technology Institute

  • Fachbereich

    • Fachbereich 2: Energy and Life Science

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  • 2021
  • Journal Article
  • • Laurence Alhrshy

• Grid Support with Wind Turbines: The Case of the 2019 Blackout in Flensburg

  Gloe, A. ., Jauch, C. ., & Räther, T. . (2021). Grid Support with Wind Turbines: The Case of the 2019 Blackout in Flensburg. Energies, 14(6), 1697. http://doi.org/10.3390/en14061697

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  The work presented in this paper aims to show how modern wind turbines can help to control the frequency in a small grid which suffers from large power imbalances. It is shown for an exemplary situation, which occurred in Flensburg’s distribution grid in 2019: a major blackout, which occurred after almost two hours in islanding operation, affecting almost the entire distribution grid, which supplies approximately 55,000 households and businesses. For the analysis, a wind turbine model and a grid support controller developed at the Wind Energy Technology Institute are combined with real measurements from the day of the blackout to generate a fictional yet realistic case study for such an islanding situation. For this case study, it is assumed that wind turbines with grid support functionalities are connected to the medium voltage distribution grid of the city. It is shown to what extent wind turbines can help to operate the grid by providing grid frequency support in two ways: By supplying synthetic inertia only, where the wind turbines can help to limit the rate of change of frequency in the islanded grid directly after losing the connection to the central European grid. In combination with the primary frequency control capabilities of the wind turbines (WTs), the disconnection of one gen set in the local power station might have been avoided. Furthermore, wind turbines with primary frequency control capabilities could have restored the grid frequency to 50 Hz shortly after the islanding situation even if the aforementioned gen-set was lost. This would have allowed connecting a backup medium voltage line to the central European grid and thereby avoiding the blackout.

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    • Gloe, Arne
    • Jauch, Clemens

  • Forschungsprojekt

    • Grenzland INNOVATIV Schleswig-Holstein

  • Abteilung/Einrichtung

    • Wind Energy Technology Institute

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  • 2021
  • Journal Article
  • • Arne Gloe
    • Prof. Dr. Clemens Jauch
    • Thomas Räther
  • • WETI

• \# Covid-19: An Exploratory Investigation of Hashtag Usage on Twitter

  Petersen, K. ., & Gerken, J. M. (2021). \# Covid-19: An Exploratory Investigation of Hashtag Usage on Twitter. Health Policy.

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    • Petersen, Kai
    • Gerken, Jan

  • Abteilung/Einrichtung

    • FLAIR - Flensburg Artificial Intelligence Research

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  • 2021
  • Journal Article
  • • Kai Petersen
    • Jan Gerken

• Arbeiten Frauen aufgrund des Ehegattensplittings weniger? — Eine empirische Untersuchung für Deutschland

  Chirvi, M. . (2021). Arbeiten Frauen aufgrund des Ehegattensplittings weniger? — Eine empirische Untersuchung für Deutschland. Steuer Und Wirtschaft, 98(2). http://doi.org/10.9785/stuw-2021-980207

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  Der Beitrag soll zur Klärung der Frage beitragen, ob das Ehegattensplitting, wie vielfach behauptet wird, einen negativen Einfluss auf das Arbeitsverhalten verheirateter Frauen hat. Hierzu kommt für Deutschland erstmals ein von Quasi-Experimenten inspirierter Ansatz zum Einsatz, bei dem anhand des allgemeinen Effekts der Heirat auf das Erwerbsverhalten der heiratenden Frauen die Wirkung des Ehegattensplittings geschätzt wird. Die Veränderung des Arbeitsverhaltens heiratender Frauen wird dabei der Veränderung bei jenen Frauen gegenübergestellt, die im gleichen Zeitraum weiterhin mit ihrem festen Partner zusammenleben, ohne zu heiraten (Kontrollgruppe). Die Ergebnisse sprechen eindeutig gegen einen unmittelbaren negativen Effekt des Ehegattensplittings auf das Erwerbsverhalten von Frauen. Jedoch reduzieren heiratende und zeitgleich ein Kind bekommende Frauen ihre Erwerbstätigkeit stärker als gebärende Frauen in der Kontrollgruppe. In Folge einer lediglich teilweisen Abschaffung des Ehegattensplittings, die in den Entwürfen zu Parteiprogrammen zur Bundestagswahl 2021 teilweise gefordert wird, sind sogar noch geringere Effekte auf das Arbeitsverhalten zu erwarten.

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    • Chirvi, Malte

  • Fachbereich

    • Fachbereich 4: Wirtschaft

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  • 2021
  • Journal Article
  • • Malte Chirvi