Irshad, M., Britto, R., & Petersen, K. (2021). Adapting Behavior Driven Development (BDD) for large-scale software systems. Journal of Systems and Software, 177, 110944.
Chirvi, M., Huber, H.-P., & Schneider, C. (2021). Biased Preferences for Wealth Taxation: The Case of Misperceived Tax Burden Consequences. TRR 266 Working Paper Series.
Abstract
The individual capacity to form personal preferences constitutes an essential element of thedemocratic process. At the same time, policies with far-reaching consequences often require profound expertise. Taxation is such an example. Due to its complex character, bounded rationality might induce biases causing other outcomes than intended. This paper quantifies shifts in stated preferences for wealth taxation caused by misperceived burden consequences of commonly politically discussed tax parameters: tax allowances and tax rates. For this, we conducted a randomized survey experiment with over 1,200 respondents in Germany. In a 2 by 2 design, our respondents were randomly selected to indicate both their preferred tax allowance and tax rate for either a yearly or a one-time wealth tax. Our treatment group was provided with easy-to-understand information on the resulting effective lifetime tax burden for the respective instrument. We find the preferred effective tax rate to drop by almost 15 percentage points for a yearly wealth tax if our participants are fully informed, whereas we do not find this effect for the one-time wealth tax. In terms of informed preferences our respondents preferthe yearly wealth tax over a one time wealth tax if misperceptions are resolved: the preferred effective tax burden of a yearly wealth tax is about 25 percentage points higher (40.0% vs.15.2%). While not being able to fully explain the source of this difference, we argue that both the total burden as well as the reasonability of single payments might be factors that form preferences for tax parameters.
Pfeiffer, W. T., Witte, F., Tuschy, I., & Bauer, S. (2021). Coupled power plant and geostorage simulations of porous media compressed air energy storage (PM-CAES). Energy Conversion and Management, 249, 114849. http://doi.org/https://doi.org/10.1016/j.enconman.2021.114849
Abstract
Porous media compressed air energy storage (PM-CAES) systems that use porous geological formations such as sandstone may provide large storage capacities in future energy systems based primarily on fluctuating renewable energy sources. In CAES systems, the instantaneous power and stored energy are closely linked to the storage pressure and the mass flow rate achievable in the geological reservoir. Therefore, a coupled simulator that accurately represents the power plant, the geostorage site, and their interactions during all potential PM-CAES system operation modes is presented in this paper. Using adiabatic and diabatic power plant topology test designs, strong feedback between the achievable storage rates and capacities of the chosen power plant design and geostorage site are found, thus confirming the benefit of this integrated modelling approach. Using a generic, highly cyclic load profile for daily peak shaving with charging and discharging rates of 100 MW and an adiabatic power plant topology, it is found that all discharging targets can be met but the achievable charging rates decrease to approximately 95 MW due to increased pressure in the geostorage after approximately 10 cycles. When a diabatic power plant design is considered, a long-term decrease in the geostorage pressure is found. Correspondingly, the charging power always meets the specifications, while the discharging power decreases slowly from the 20th storage cycle onwards to 79 MW in the 31st cycle. The newly developed simulation tool thus allows one to predict achievable power rates and geostorage pressures for PM-CAES systems, enabling the identification of efficient PM-CAES designs.
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
Abstract
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.
Lenz, F., Fock, M., Kramer, T., Petersen, Y., & Teistler, M. (2021). A virtual reality game to support visuospatial understanding of medical X-ray imaging. In 2021 IEEE 9th International Conference on Serious Games and Applications for Health (SeGAH). Dubai, United Arab Emirates.
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
Wohlin, C., Papatheocharous, E., Carlson, J., Petersen, K., egroth, E. A., Axelsson, J., … others,. (2021). Towards evidence-based decision-making for identification and usage of assets in composite software: A research roadmap. Journal of Software: Evolution and Process, 33, e2345.
Ebbers, I. (2021). Entrepreneurship Education als Beitrag zur Weiterung der Horizonte.
Abstract
[... Der Beitrag] verfolgt die Frage, wie eine Entrepreneurship Education, verstanden als Erziehung zum unternehmerisches Denken und Handeln, im Rahmen allgemein-bildender Beschulung und mit dem Ziel einer allgemeinbildenden Wirksamkeit so angelegt werden kann, dass sie einen Beitrag zur Horizontweitung der Lernenden leisten kann. Um diese Frage beantworten zu können, soll im weiteren Verlauf der Bildungsbegriff nach Klafki genutzt werden. Er bezieht sich hier im Wesentlichen auf vier Aufgaben der Bildung, welche im Folgenden vor dem Hintergrund der hier gemeinten Entrepreneurship Education genauer betrachtet werden sollen. (DIPF/Orig.).
Gloe, A., Jauch, C., Craciun, B., Zanter, A., & Winkelmann, J. (2021). Influence of Continuous Provision of Synthetic Inertia on the Mechanical Loads of a Wind Turbine. Energies, 14(16), 5185. http://doi.org/10.3390/en14165185
Abstract
In many electrical grids, the share of renewable energy generation increases. As these generators are typically connected to the grid via inverters, the level of grid inertia decreases. Such grids may therefore suffer from high rates of change of frequency during power imbalances. Modern wind turbines can help in controlling the frequency in such grids by providing synthetic inertia. A controller to provide synthetic inertia with wind turbines was developed at the Wind Energy Technology Institute in collaboration with Suzlon Energy. For this controller the influence of providing synthetic inertia on the mechanical loads of the wind turbine is assessed for different grid frequency scenarios. Such a scenario-based load analysis has not been published before, especially as the scenarios are derived from real measurements. The effect of the loads strongly depends on the analyzed grid frequency behavior. Ten months of high quality grid frequency measurements of the Indian grid are analyzed in order to derive inputs for the load calculation. Different types of grid frequency abnormities are identified and categorized with respect to their severity. Based on the observed occurrences of the grid frequency abnormities, realistic scenarios for the load calculations are chosen. The load calculations are performed for a state-of-the-art Suzlon wind turbine generator. The load increases caused by the supply of synthetic inertia are calculated for individual components assuming an otherwise undisturbed power production of the wind turbine in turbulent wind. Furthermore, a hardware-in-the-loop test bench is used to show how the measured grid frequencies are actually perceived by the control system of a typical wind turbine. The original frequency data were recorded with high quality measurement equipment, which is faster and more accurate than a multi-function relay, often used in wind turbines. For exemplary time traces, the effect of the reduced measurement accuracy on the reaction of the wind turbine is shown. This aspect has not been investigated in the literature yet. The results show that wind turbines can provide synthetic inertia without a considerable effect on the lifetime of the wind turbine. However, there are still problems with providing synthetic inertia reliably at high power operating points, which have to be solved.