BWL, insb. Wirtschaftsinformatik

Verschiedene Maßnahmen zum angestrebten Klimaschutz gehen mit einer verstärkten Verwendung elektrischer Energie einher. Dabei stellt sich bei der Nutzung volatiler regenerativer Energiequellen wie Sonne und Wind die Herausforderung einer räumlichen und zeitlichen Abstimmung von Erzeugung und Verbrauch elektrischer Energie. Batteriespeicher können hier einen effektiven Beitrag leisten (z.B. in Haushalten, im Verkehrssektor und in der Industrie). Im Hinblick auf die Wirtschaftlichkeit erfordert dies eine zielgerichtete Dimensionierung und Betriebsführung entsprechender Batterie-Energie-Speichersysteme (BESS) unter Berücksichtigung der für den Verschleiß und die Alterung von (Lithiumionen-)Batterien relevanten Faktoren. Hierbei wird zwischen der nutzungsabhängigen (zyklischen) und der altersabhängigen (kalendarischen) Degradation unterschieden, welche die noch verfügbare Kapazität (gemäß State of Health, SoH) und damit die Lebensdauer und entsprechende Kosten von Batterien nicht-linear beeinflussen. In der Literatur finden sich hierzu unterschiedliche Annahmen und Ansätze, wie sich die Verwendung von Batterien auf den SoH auswirkt und wie ein wirtschaftlicher Einsatz von Batterien unter Berücksichtigung der Degradationseffekte gestaltet werden kann. Dieser Beitrag gibt einen Überblick über diese Problematik unter Berücksichtigung neuerer Arbeiten aus der Literatur und dort noch nicht ausreichend adressierter Aspekte. Es wird ein integratives Modell für die Auslegung und den Betrieb von BESS entwickelt, welches die Auswirkungen beider Degradationsarten auf die Dimensionierung und Nutzung eines BESS einbezieht. Dabei wird berücksichtigt, dass ein abnehmender SoH bei gleichbleibendem Energiebedarf zu einer höheren Degradation führt, da dann die Zyklenanzahl zunimmt und das BESS schneller degeneriert. Darüber hinaus ist zu beachten, dass die Betriebsführung von BESS mit verschiedenerlei Unsicherheiten behaftet ist (sowohl bei der Erzeugung als auch beim Verbrauch, was sich auch in dynamischen Preisen im Stromnetz zeigt). Das formulierte Basiskonzept zur wirtschaftlichen Auslegung des Batteriebetriebs soll die Grundlage für weiterführende stochastische sequenzielle Entscheidungsverfahren und zugehörige Analysen bilden, die zu einer kosteneffizienten Dimensionierung und Betriebsführung von BESS beitragen.

Increasing amounts of data and simulations in scientific areas enforce the need of improved software performance. The maintaining scientific staff is often not primarily trained for this purpose or lacks personnel and time to address software performance issues. A particular aim of the dtec.bw-funded project hpc.bw is to tackle some of these shortcomings. A pillar of the hpc.bw agenda is the offer of a low-threshold consultancy and development support focused on performance engineering. This paper provides an insight on our related activities. We illustrate the structure of our annual calls for short-term performance engineering projects, we outline our results at the example of the performance engineering project “benEFIT - Numerical simulation of non-destructive testing in concrete”, and we draw a first conclusion on the current procedure.

The dtec.bw project CoupleIT! – IT-based sector coupling: Digitally controlled fuel cell and electrolyzer technologies for stationary and mobile applications is an interdisciplinary approach to combine a wide range of competencies from disciplines as varied as electrical power systems, economic and social sciences, computer sciences and networks as well as sustainable development and social acceptance research. As such, this article is composed of individual contributions, constituting the main chapters that showcase general approaches and motivations but also concrete results. This compendium article starts in with a delineation of the motivation behind research in so-called microgrids composed of fuel cell and electrolyzer components and a presentation of the microgrid architecture opted for in this project. Chapter two goes into more detail on the side of electrical engineering and the feasibility of a parallel operation of inverters in microgrids to achieve the ability for an upscaling. Chapter three highlights economic and technological factors for an economically viable and grid-maintaining deployment of a hydrogen-based energy system. In addition, degradation of Li-ion batteries is discussed against the background of their flexible operation in a microgrid and other scenarios. Chapter four grants a glimpse into the field of computer science and the possibility to use artificial intelligence and neural networks for a new way to simulate the behaviour of matter on atomic and molecular scales. This approach holds potential to increase the efficiency of fuel cells by improving the molecular design of fuel cell membranes used within this project. Chapter five elucidates the intricacies of secure communication within one but also between multiple microgrids, an important aspect for achieving a resilient system. Chapter six concludes this compendium by highlighting the human perspective seen from the field of psychological acceptance research nested in the broader context of sustainable development. Among other things, areas of potential barriers to a public acceptance of hydrogen technology are identified and ways to overcome those barriers proposed. This interdisciplinary round trip starts with electrical engineering (chapters one and two), economic and social sciences (chapter three), followed by computer sciences (chapter four) and computer networks (chapter five) whence the baton is passed for one last time to the field of sustainable development and psychological acceptance research (chapter six).

In the scope of the dtec.bw project hpc.bw, innovative HPC hardware resources were procured to investigate their performance for HSU-relevant compute-intensive software. Benchmarks for different software packages were conducted, and respective results are reported and documented in the following, considering the Intel Xeon architecture used in the HPC cluster HSUper, AMD EPYC 7763 and ARM FX700.

Benchmarking the performance of one’s application in high performance computing (HPC) systems is critically important for reducing runtime and energy costs. Yet, accessing the plethora of relevant metrics that impact performance is often challenging, particularly for users without hardware experience. In this paper, we introduce the novel benchmarking tool xbat developed by MEGWARE GmbH. xbat requires no setup from the user side, and it allows the user to run, monitor and evaluate their application from the tool’s web interface, consolidating the entire benchmarking process in an approachable, intuitive workflow. We demonstrate the capabilities of the tool using benchmark applications of varying complexity and show that it can manage all aspects of the benchmarking workflow in a seamless manner. In particular, we focus on the open-source molecular dynamics research software ls1 mardyn, and the closed-source optimisation package Gurobi. Both packages present unique challenges. Mixed-integer programming solvers, such as those integrated in the Gurobi software, exhibit significant performance variability, so that seemingly innocuous parameter changes and machine characteristics can affect the runtime drastically, and ls1 mardyn comes with an auto-tuning library AutoPas, that enables the selection of various node-level algorithms to compute molecular trajectories. Focusing on these two packages, we showcase the practicality, versatility and utility of xbat, and share its current and future developments.

Da sich die Entwicklung von E-Government in Deutschland seit Jahren in einer Stagnation befand, verabschiedete die Bundesregierung im Jahr 2013 das sogenannte E-Government-Gesetz, flankiert von unterschiedlichen Initiativen. In den Jahren zuvor hatte sich im Bereich der Informationstechnologie mit Enterprise-Content-Management-Systemen eine neue Art von Plattform etabliert, die sich insbesondere zur Abbildung dokumentengestützter Prozesse und somit auch der digitalen Verwaltung nutzen lässt. Die Einführung eines solchen Systems im Zusammenhang mit einer Umgestaltung der Organisation hin zu einer durchgreifenden Digitalisierung ist ein komplexes Projekt mit vielen Wechselwirkungen. Da bürokratische Organisationen durch grundsätzlich vergleichbare Wirkmechanismen gekennzeichnet sind, wird in dieser Arbeit ein Rahmenmodell entwickelt, das die Einführung von Enterprise-Content-Management-Systemen in bürokratische Organisationen zum Zwecke einer elektronischen Verwaltungsarbeit umfassend abbildet und somit zur Vereinfachung, Standardisierung und Koordinierung dieser Projekte beitragen soll. Aufbauend auf rechtlichen Rahmenbedingungen, vergleichbaren Rahmenmodellen anderer Problemklassen und unter Nutzung von Expertenwissen sowie Nutzervorstellungen wird in dieser Arbeit unter Zuhilfenahme der Design-Science-Forschungsmethodik ein entsprechendes Rahmenmodell als Artefakt entwickelt, vorgeschlagen und anschließend im Rahmen einer Fallstudie empirisch evaluiert.

Recently, new benchmark instances (MMLIB) have been presented by Van Peteghem and Vanhoucke (2014). These instances have been designed in such way that the well known pre-processing procedure of Sprecher et al. (1997) does not have any impact on any instance. We developed a technique that could be applied to the new data set to reduce the number of modes per activity. Computational results show that the procedure is highly effective in reducing the number of modes. A reduction was possible for 2,026 of the 4,320 MMLIB instances.

Battery electric freight vehicles have the potential to mitigate the local urban road freight transport emissions, but their numbers are still insignificant. Logistics companies often consider electric vehicles as too costly compared to vehicles powered by combustion engines. The current literature suggests that increasing the mileage can maximize the competitiveness of electric freight vehicles. In this manuscript we develop a generic model to determine the cost-optimal balance between a high utilization of electric freight vehicles – which often have low operational costs – and their required expensive battery replacements. Our work relies on empirical findings of the real-world energy consumption from a large German field test with vehicles of 7.5 and 12 tons, respectively. Our results suggest that increasing the range to the technical maximum by intermediate (quick) charging and multi-shift usage is not the most cost-efficient strategy in every case. A low daily mileage is more cost-efficient at high energy prices or consumptions, relative to the diesel prices or consumptions, or if the battery is not safeguarded by a long battery warranty. In practical applications our model may help companies to choose the most suitable electric vehicle for the application purpose, or the optimal trip length from a given set of options. For policymakers, our analysis provides insights on the relevant parameters that may either reduce the cost-gap at lower daily mileages, or increase the utilization of electric urban freight vehicles, in order to abate the negative impact of urban road freight transport on the environment.

In this work we consider the Coach Trip with Shuttle Service Problem (CTSSP), which is a routing problem where passengers have to be transported from bus stops to a central hub with a fleet of coaches and shuttles. The capacity of each vehicle must not be exceeded and for each group of passengers waiting at a bus stop there is a maximal travel time that must not be exceeded while travelling to the hub. Shuttles can use bus stops as transfer points to drop their passengers from which they have to be picked up by a coach. Coaches must end their trip at the hub while shuttles can stop at any bus stop. The goal is to minimize costs. The costs consist of travelling costs of the used vehicles plus fixed costs for the usage of the shuttles. We prove the computational complexity of the problem and present a novel mathematical model for the CTSSP. This model is implemented in CPLEX and the optimal solution of the "example" instance of the VeRoLog Solver Challenge 2015 is shown.