@inproceedings{SchummJosephSchrollDeckeretal., author = {Schumm, Michael and Joseph, Saskia and Schroll-Decker, Irmgard and Niemetz, Michael and Mottok, J{\"u}rgen}, title = {Required competences in software engineering - pair programming as an instrument for facilitating life-long learning}, series = {15th International Conference on Interactive Collaborative Learning and 41st International Conference on Engineering Pedagogy, Villach}, booktitle = {15th International Conference on Interactive Collaborative Learning and 41st International Conference on Engineering Pedagogy, Villach}, doi = {10.1109/ICL.2012.6402229}, abstract = {The professional requirements in software engineering have become highly volatile due to the complexities of project development and rapid and innovative changes occurring in the field. Therefore, the development of inter-personal and social competences has gained central importance in the training of software developers. The following text will present a concept allowing to acquire competences by using Pair Programming as an instrument. Moreover, arrangements for learning and teaching will be presented facilitating the acquisition of these competences. By approaching the issue of competence acquisition on a technical as well as on an educational and social level, lifelong learning is facilitated and supported.}, language = {en} } @inproceedings{JosephSchummSchrollDeckeretal., author = {Joseph, Saskia and Schumm, Michael and Schroll-Decker, Irmgard and Niemetz, Michael and Mottok, J{\"u}rgen}, title = {Anmerkungen zur Kompetenz-Performanz-Relation: Software Engineering im Spannungsfeld der beruflichen Anforderungen}, series = {Tagungsband 5th Embedded Software Engineering Kongress, 3. bis 7. Dezember 2012, Sindelfingen}, booktitle = {Tagungsband 5th Embedded Software Engineering Kongress, 3. bis 7. Dezember 2012, Sindelfingen}, language = {de} } @inproceedings{NiemetzFuhrmannFarmbauer, author = {Niemetz, Michael and Fuhrmann, Thomas and Farmbauer, Michael}, title = {Comprehensive Amateur Radio Education including Public Outreach}, series = {IEEE Integrated STEM Education Conference (ISEC), 16-16 March 2019, Princeton, NJ, USA}, booktitle = {IEEE Integrated STEM Education Conference (ISEC), 16-16 March 2019, Princeton, NJ, USA}, publisher = {IEEE}, doi = {10.1109/ISECon.2019.8882078}, pages = {98 -- 103}, abstract = {An amateur radio lecture was developed and is conducted within the general education program of the Ostbayerische Technische Hochschule Regensburg. This course enables the students to participate in a variety of activities within the university. Different learning formats for communication engineering are carried out in combination with an amateur radio station of the university. Additionally, some of the projects serve as anchor points for increased visibility of the university in local society, e.g. by carrying out public events in connection with the local amateur radio community. It is seen that this course together with the amateur radio station have several positive effects for technical education and university visibility.}, language = {en} } @inproceedings{WetzelReindlMeieretal., author = {Wetzel, Daniel and Reindl, Andrea and Meier, Hans and Niemetz, Michael and Farmbauer, Michael}, title = {A Customized Python Interface for Windows OS for a Low Budget USB-to-CAN-Adapter}, series = {International Conference on Electrical, Computer and Energy Technologies (ICECET 2022): 20-22 July 2022, Prague, Czech Republic}, booktitle = {International Conference on Electrical, Computer and Energy Technologies (ICECET 2022): 20-22 July 2022, Prague, Czech Republic}, publisher = {IEEE}, address = {Piscataway, NJ, USA}, isbn = {978-1-66547-087-2}, doi = {10.1109/ICECET55527.2022.9872574}, pages = {5}, abstract = {Over the last three decades, the Controller Area Network (CAN) has become the dominant communication in embedded systems. Especially for automotive systems it offers advantages including high robustness, low error rate and high reliability combined with low power consumption. Therefore, learning the basics of this bus system is substantial in this field. Nowadays, various media about the functionality and use of CAN exist which make it easy to read into the topic. But often, theory alone is not sufficient. To deepen the understanding, practical implementation contributes significantly. However, affordable and easy-to-use CAN devices for training purposes are scarce. Existing equipment can be divided into expensive professional devices, which have many functions and inexpensive ones for hobbyists, which require difficult configurations. Therefore, a practical solution is a low-budget device equipped with an overlay which deals with the time consuming configurations. This paper covers the development of a python interface for a purchasable cost effective CAN device for Windows OS. The intention is to create an easy-to-use program that enables beginners to get in touch with CAN and collect practical experience. At the start, a brief explanation of the CAN functionality is given. After that, we introduce the hardware used in this project. Next, the software part covers the development of the interface and the integration of this interface into python-can. Furthermore, a virtual playground is introduced for testing purposes. Also, to demonstrate the functionality of the interface, a test program is executed in conjunction with a logic analyzer.}, language = {en} } @inproceedings{DiehlWolffFuhrmannetal., author = {Diehl, Andreas and Wolff, Lilli and Fuhrmann, Thomas and Niemetz, Michael and M{\"o}rtlbauer, Stefanie and Dirnberger, Sandra}, title = {Compact Freshmen Welcome Seminar for Engineering Students}, series = {Procedia - Social and Behavioral Sciences}, booktitle = {Procedia - Social and Behavioral Sciences}, number = {228}, publisher = {Elsevier}, doi = {10.1016/j.sbspro.2016.07.007}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-31034}, pages = {45 -- 52}, abstract = {The Faculty of Electrical Engineering and Information Technology of the OTH Regensburg developed and implemented a compact freshmen seminar for the afternoon of the first day of study. The intention of this seminar is to help the freshmen during their transition between school and study without losing lecture time in the first semester. The concept was tested with one small study group at the beginning of the summer semester 2015. To rate the impact of the seminar and to find aspects for continuous improvement an evaluation method was developed and used. Due to the good student resonance during the first run, this introduction seminar was held again in the winter semester 2015/16. It is planned to integrate this seminar as a regular session for all freshmen of the faculty curriculum and monitor the long-term effects of student motivation and success.}, language = {en} } @misc{ReindlErikssonNiemetzetal., author = {Reindl, Andrea and Eriksson, Lars and Niemetz, Michael and Sangyoung, Park and Meier, Hans}, title = {Control Concepts for a Decentralized Battery Management System Decentralized Battery Management System Global Control Level}, series = {16th International Renewable Energy Storage Conference (IRES2022), 20 to 22 September 2022, D{\"u}sseldorf}, journal = {16th International Renewable Energy Storage Conference (IRES2022), 20 to 22 September 2022, D{\"u}sseldorf}, publisher = {Eurosolar}, language = {en} } @inproceedings{HobelsbergerDumkeMottoketal., author = {Hobelsberger, Martin and Dumke, Reiner and Mottok, J{\"u}rgen and Niemetz, Michael and Wirrer, Gerhard}, title = {An Experience-Based Repository of Reusable Components for an Component-Based Automotive Software System}, series = {Applied Software Measurement, proceedings of the joined International Conferences on Software Measurement IWSM/MetriKon/Mensura 2010, 10.-12. November 2010, Stuttgart, Germany}, booktitle = {Applied Software Measurement, proceedings of the joined International Conferences on Software Measurement IWSM/MetriKon/Mensura 2010, 10.-12. November 2010, Stuttgart, Germany}, pages = {218 -- 240}, language = {en} } @inproceedings{AlfransederKrapfMaderetal., author = {Alfranseder, Martin and Krapf, Tobias and Mader, Ralph and Niemetz, Michael and Mottok, J{\"u}rgen and Siemers, Christian}, title = {An Efficient Partitioning Strategy for Runnables in Weakly Dependent Tasks on Embedded Multi-Core Systems}, series = {Embedded real-time software and systems (ERTS² 2014), Feb 2014, Toulouse, France}, booktitle = {Embedded real-time software and systems (ERTS² 2014), Feb 2014, Toulouse, France}, abstract = {With multi-core controllers entering the area of automotive control ECUs, strategies for parallelizing the control- algorithms come into focus. This paper deals with a special part of automotive powertrain software, called state transitions. Since dependencies between runnables executed there are weak, the transitions provide a good basis for parallelization. We present a strategy of how to distribute efficiently the execution of runnables to different cores while taking care of inner and outer dependencies. The strategy is accompanied by two case studies demonstrating the performance of the concept. The first one is carried out to find the most efficient strategies of parallelize state transitions based on randomly generated, simulated state transitions. In the second one, the developed partitioning strategies are applied to a real software project for an automotive powertrain system.}, language = {en} } @inproceedings{AlfransederMuchaSchmidhuberetal., author = {Alfranseder, Martin and Mucha, Matthias and Schmidhuber, Stefan and Sailer, Andreas and Niemetz, Michael and Mottok, J{\"u}rgen}, title = {A modified synchronization model for dead-lock free concurrent execution of strongly interacting task sets in embedded systems}, series = {2013 International Conference on Applied Electronics (AE 2013), IEEE, 10-12 September 2013, Pilsen, Czech Republic}, volume = {18}, booktitle = {2013 International Conference on Applied Electronics (AE 2013), IEEE, 10-12 September 2013, Pilsen, Czech Republic}, pages = {13 -- 18}, abstract = {Global scheduling algorithms are very promising for application in embedded real-time systems using multi-core controllers. In this paper we want to make a first step forward to apply such scheduling methods on real existing systems. Especially a new resource model is necessary to avoid deadlocks, as this goal can not be achieved by using the standard OSEK Priority Ceiling Protocol when shared global resources are in use. We also introduce the new metric mean Normalized Blocking Time in order to be able to compare locking mechanisms according to the timing effects of their blocking behavior. Finally we give a simulative application example of the new metric by the use of two different kinds of semaphore models and an example task set typical for existing embedded real-time systems in the automotive powertrain environment.}, language = {en} } @inproceedings{ReindlMeierNiemetz, author = {Reindl, Andrea and Meier, Hans and Niemetz, Michael}, title = {Scalable, Decentralized Battery Management System Based on Self-organizing Nodes}, series = {Architecture of computing systems - ARCS 2020: 33rd international conference, Aachen, Germany, May 25-28, 2020, proceedings}, volume = {12155}, booktitle = {Architecture of computing systems - ARCS 2020: 33rd international conference, Aachen, Germany, May 25-28, 2020, proceedings}, editor = {Brinkmann, Andr{\´e} and Karl, Wolfgang and Lankes, Stefan and Tomforde, Sven and Pionteck, Thilo and Trinitis, Carsten}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-030-52793-8}, doi = {10.1007/978-3-030-52794-5_13}, pages = {171 -- 184}, abstract = {Due to the transition to renewable energy sources and the increasing share of electric vehicles and smart grids, batteries are gaining in importance. Battery management systems (BMSs) are required for optimal, reliable operation. In this paper, existing BMS topologies are presented and evaluated in terms of reliability, scalability and flexibility. The decentralisation of BMSs and associated advantages are shown. A scalable, reconfigurable BMS based on a distributed architecture of self-organized, locally controlled nodes is proposed. For distributed system control, producers, batteries and consumers each are equipped with a local microcontroller based control unit, which monitors and controls the local parameters with its own computing and communication resources. Features, advantages and challenges to overcome of the proposed approach are described.}, language = {en} } @inproceedings{HerboldReindlMeieretal., author = {Herbold, Florian and Reindl, Andrea and Meier, Hans and Niemetz, Michael and Kr{\"a}mer, Stefan}, title = {Secure Software Updates: Challenges and Solutions for Embedded IoT Systems}, series = {Proceedings of the 9th Embedded Systems Workshop: July 1-3, 2021 Horomerice, Czech Republic}, booktitle = {Proceedings of the 9th Embedded Systems Workshop: July 1-3, 2021 Horomerice, Czech Republic}, editor = {Kub{\´a}tov{\´a}, Hana and Fišer, Petr and Boreck{\´y}, Jaroslav}, isbn = {978-80-01-06858-8}, pages = {5 -- 13}, abstract = {The invention of the internet made the development of intelligent networking of millions of embedded systems possible. This enabled smart buildings, power grids and cities as well as applications in the fields of health, agriculture and industry. These systems frequently perform safety-critical applications and operations. This makes it urgent to protect these sensible systems as effectively as possible. Especially firmware updates are often the weak point in the systems. If unauthorised persons gain access to the system during the update, malware can be injected or sensitive data can be read and stolen. This paper describes the challenges of secure firmware updates. To protect an embedded system from potential attackers, the concepts integrity, authenticity and confidentiality have to be adhered during the update process. Otherwise, there is an increased risk of modifying or reverse engineering the firmware image. Likewise, inadequately protected software can enable the installation of third-party firmware as well as the installation of firmware on a third-party system. Threat prevention is presented with solutions derived from functional safety and IT security. Aspects of protection against errors in the transmission of updates and against attacks aiming to compromise the system are explained. Finally, a possible sequence of a secure update process is examined in detail for a real embedded system implementation. For this purpose, the preparation, transmission and installation of a firmware update in the bootloader are discussed}, language = {en} } @inproceedings{AbkeBruneHauptetal., author = {Abke, J{\"o}rg and Brune, Philipp and Haupt, Wolfram and Hagel, Georg and Landes, Dieter and Mottok, J{\"u}rgen and Niemetz, Michael and Pfeiffer, Volkhard and Studt, Reimer and Schroll-Decker, Irmgard and Sedelmaier, Yvonne}, title = {Evelin - ein Forschungsprojekt zur systematischen Verbesserung des Lernens von Software Engineering}, series = {Tagungsband 5th Embedded Software Engineering Kongress, 3. bis 7. Dezember 2012, Sindelfingen}, booktitle = {Tagungsband 5th Embedded Software Engineering Kongress, 3. bis 7. Dezember 2012, Sindelfingen}, isbn = {978-3-8343-2407-8}, pages = {653 -- 658}, language = {de} } @inproceedings{ReindlMeierNiemetzetal., author = {Reindl, Andrea and Meier, Hans and Niemetz, Michael and Park, Sangyoung}, title = {Decentralized Battery Management System with Customized Hardware Components}, series = {IEEE 19th Student Conference on Research and Development (SCOReD), Sustainable Engineering and Technology towards Industry Revolution: 23-25 Nov. 2021, Kota Kinabalu, Malaysia}, booktitle = {IEEE 19th Student Conference on Research and Development (SCOReD), Sustainable Engineering and Technology towards Industry Revolution: 23-25 Nov. 2021, Kota Kinabalu, Malaysia}, publisher = {IEEE}, doi = {10.1109/SCOReD53546.2021.9652737}, pages = {350 -- 355}, abstract = {With an increasing number of sold electric vehicles (EVs), a large number of used batteries will be at disposal. How to deal with these resources is one of the major challenges in reducing the environmental impact of batteries throughout their entire life cycle. Heterogeneous cell parameters due to the different usage histories are a challenge for second-life use. The effort and cost of remanufacturing required to test and assemble a new battery pack is a further concern. Systems that combine battery packs/modules without full reassembly offer advantages such as cost and reusability. A decentralized battery management system (DBMS) provides a suitable architecture for such systems involving different types of batteries. In this paper, an architecture for a decentralized, battery state-dependent control is shown. The proposed DBMS supports various types of batteries, is scalable and flexibly adaptable for a wide range of applications. Despite the significant advantages, there are increased requirements to meet for the hardware implementation and the applied control strategies. Therefore, the necessary hardware components and their requirements are described and the hardware implementations are provided.}, language = {en} } @article{SchoepeHaenninenNiemetz, author = {Schoepe, Wilfried and H{\"a}nninen, Risto and Niemetz, Michael}, title = {Breakdown of Potential Flow to Turbulence Around a Sphere Oscillating in Superfluid 4He Above the Critical Velocity}, series = {Journal of low temperature physics}, volume = {178}, journal = {Journal of low temperature physics}, publisher = {Springer Nature}, doi = {10.1007/s10909-014-1265-7}, pages = {383 -- 391}, abstract = {The onset of turbulent flow around an oscillating sphere in superfluid 4He is known to occur at a critical velocity where is the circulation quantum and is the oscillation frequency. But it is also well known that initially in a first up-sweep of the oscillation amplitude, can be considerably exceeded before the transition occurs, thus leading to a strong hysteresis in the velocity sweeps. The velocity amplitude where the transition finally occurs is related to the density of the remanent vortices in the superfluid. Moreover, at temperatures below ca. 0.5 K and in a small interval of velocity amplitudes between and a velocity that is about 2 \% larger, the flow pattern is found to be unstable, switching intermittently between potential flow and turbulence. From time series recorded at constant temperature and driving force, the distribution of the excess velocities is obtained and from that the failure rate. Below 0.1 K we also can determine the distribution of the lifetimes of the phases of potential flow. Finally, the frequency dependence of these results is discussed.}, language = {en} } @inproceedings{ReindlSingerMeieretal., author = {Reindl, Andrea and Singer, Thomas and Meier, Hans and Niemetz, Michael and Park, Sangyoung}, title = {Framework to Test DC-DC Converters Developed for a Decentralized Battery Management System}, series = {2021 International Conference on Applied Electronics (AE): 7-8 Sept. 2021, Pilsen, Czech Republic}, booktitle = {2021 International Conference on Applied Electronics (AE): 7-8 Sept. 2021, Pilsen, Czech Republic}, publisher = {IEEE}, doi = {10.23919/AE51540.2021.9542882}, pages = {1 -- 6}, abstract = {DC- DC converters control the power flow and thus the power distribution between the components on different voltage levels. They are essential for (dis)charging batteries and influence the safety and stability of the entire battery management system (BMS). Therefore, testing the functionality and the reliability of DC-DC converters is crucial. This is especially true for decentralized battery management systems (DBMS), where multiple nodes communicate to collectively control the system. The used DC-DC converters are modified to parameterize them during operation via microcontroller interfaces. Integrating the communication into the control loop requires an analysis of the control behavior due to additional delays. Therefore, this paper proposes a framework to test DC-DC converters considering the control and communication perspectives. The response time, the control accuracy and stability of these DC-DC converters, e.g., under continuous and abrupt load changes, are measured in automated tests. The dedicated software framework simulates the DBMS and stimulates the hardware components (e.g. electronic loads, data acquisition) via respective interfaces (CAN, RS232). This allows the test of various DC-DC converters with flexibly adaptable load and power generation profiles. An initial application validates the test framework by verifying the aforementioned aspects and thus the applicability of a DC-DC converter within the DBMS.}, language = {en} } @inproceedings{FuhrmannNiemetz, author = {Fuhrmann, Thomas and Niemetz, Michael}, title = {Planned Chaos in Electrical Engineering Education}, series = {6th International Conference on Higher Education Advances (HEAd'20): 02.06.2020 - 05.06.2020, Valencia}, booktitle = {6th International Conference on Higher Education Advances (HEAd'20): 02.06.2020 - 05.06.2020, Valencia}, publisher = {Universitat Polit{\`e}cnica de Val{\`e}ncia}, isbn = {9788490488119}, doi = {10.4995/head20.2020.10989}, abstract = {This paper presents the idea to intentionally introduce planned chaos into electrical engineering lectures and lab courses to improve students' learning success. The reason to present this idea are several personal experiences in daily teaching. If students experience some uncertainty in their study program, it is seen that they have higher challenges and therefore higher learning success in managing uncertain situations. In these ways, students acquire methodical and social competences to deal with uncertainty and achieve productive results in an unstable working environment. If, however, the chaos is too large, students are over-strained with the situation, distracted from the actual learning targets and consequently learning results will be worse, drop-out rates will increase and they will be frustrated. The beneficial level of uncertainty depends on the student culture, academic progress and personality characteristics. The competence to deal with complex situations is essential for later professional life where unexpected circumstances occur regularly. Introducing planned chaos into lectures and lab courses has not to be confused with a missing didactic concept and is no justification for a bad preparation. Planned chaos is a demanding concept for professors to find the right implementation for an optimized learning outcome. These described findings are experienced from practical work and student evaluations.}, language = {en} } @inproceedings{ReindlMeierNiemetz, author = {Reindl, Andrea and Meier, Hans and Niemetz, Michael}, title = {Software Framework for the Simulation of a Decentralized Battery Management System Consisting of Intelligent Battery Cells}, series = {2019 IEEE Student Conference on Research and Development (SCOReD), 15-17 Oct. 2019, Bandar Seri Iskandar, Malaysia}, booktitle = {2019 IEEE Student Conference on Research and Development (SCOReD), 15-17 Oct. 2019, Bandar Seri Iskandar, Malaysia}, doi = {10.1109/SCORED.2019.8896284}, pages = {75 -- 80}, abstract = {Conventional battery management systems typically adopt hierarchical master-slave architectures. With regard to an uninterruptible power supply, the most significant disadvantage of central structures is the dependency of the errorfree function of the superior master board. The decentralized battery management system presented in this paper, consisting of consumers, generators and intelligent battery cells, is controlled without any central coordination authority. For this purpose, an intelligent control algorithm and a leader election algorithm are implemented on the microcontrollers of the battery cells. To test different control and election strategies, a software framework is presented for the complete simulation of the decentralized battery management system consisting of equal participants.}, language = {en} } @article{SteinkirchnerFuhrmannNiemetz, author = {Steinkirchner, Alfons and Fuhrmann, Thomas and Niemetz, Michael}, title = {Channel Coded Processor for Enhanced Safety}, series = {International Journal of Future Computer and Communication (IJFCC)}, volume = {6}, journal = {International Journal of Future Computer and Communication (IJFCC)}, number = {2}, publisher = {International Association of Computer Science and Information}, address = {Singapore}, issn = {2010-3751}, doi = {10.18178/ijfcc.2017.6.2.489}, pages = {58 -- 62}, abstract = {Several concepts are known for improving processor safety, all of them having their pros and cons. Some are very resource intensive, others have limited capabilities regarding the provided error safety. In this paper we use research on channel coding of noisy communication channels known from communication theory as an analogy to random bit errors in processors. We incorporate this knowledge into processor design to suggest a new error correction concept by using channel coding in processors. The new concept of a Channel Coded Processor could provide effective implementation of redundancy by the channel coding that enables error correction. The concept could also create a complete chain of redundancy in all areas and components of the processor ranging from the code compiler through the processing hardware to the output of the information.}, language = {en} } @inproceedings{FuhrmannNiemetz, author = {Fuhrmann, Thomas and Niemetz, Michael}, title = {Transdisciplinary Bachelor Course Connecting Business and Electrical Engineering}, series = {4th International Conference on Higher Education Advances (HEAd'18), 2018, Universitat Polit{\`e}cnica de Val{\`e}ncia, Val{\`e}ncia}, booktitle = {4th International Conference on Higher Education Advances (HEAd'18), 2018, Universitat Polit{\`e}cnica de Val{\`e}ncia, Val{\`e}ncia}, doi = {10.4995/HEAd18.2018.8056}, abstract = {The OTH Regensburg has a broad variety of study programs in technical, business, social and health sciences. Up to now there is no integral connection in the bachelor curricula between business and technical faculties except for some small subjects. The scope of this project is to develop a new course specialization which connects engineering and business thinking. Electrical engineering students should learn basics of business science and how managers think. Business students should vice versa learn fundamentals of engineering and how engineers solve problems. Students from both faculties work together in projects where they act like start-up companies developing a new product and bringing it into the market. It is seen a transdisciplinary effect: These projects gain innovative results between the disciplines compared to student projects of one isolated discipline. Evaluation results from the first two cohorts indicate high student satisfaction, high learning success as well as directions for further improvement.}, language = {en} } @inproceedings{NiemetzFuhrmann, author = {Niemetz, Michael and Fuhrmann, Thomas}, title = {Wie k{\"o}nnen wir Professorinnen und Professoren ein {\"u}berfachliches Studium vermitteln?}, series = {Tagungsband zum 3. Symposium zur Hochschullehre in den MINT-F{\"a}chern (MINT-Symposium), N{\"u}rnberg 25. und 26.09.2017}, booktitle = {Tagungsband zum 3. Symposium zur Hochschullehre in den MINT-F{\"a}chern (MINT-Symposium), N{\"u}rnberg 25. und 26.09.2017}, abstract = {Die Transdisziplinarit{\"a}t ist als wichtiger Innovationsmotor in aller Munde, entstehen doch an den Schnittstellen und in den Zwischenr{\"a}umen der etablierten Wissenschaften neue Ideen und damit die zuk{\"u}nftige Wertsch{\"o}pfung unserer Industrie. Wir alle wurden in der Welt von gestern sozialisiert, f{\"u}r die meisten T{\"a}tigkeiten in der Industrie war tiefes und spezialisiertes Fachwissen essentiell und auch ausreichend. Wir wurden zu Spezialisten ausgebildet und aufgrund dieser Kompetenz in der Arbeitswelt gesch{\"a}tzt und auch auf unsere Professuren berufen. Doch ist dies eine ausreichende Basis, um unsere Absolventinnen und Absolventen auf die neue komplexe Welt ubiquit{\"a}r verf{\"u}gbaren und durchsuchbaren Wissens ad{\"a}quat vorzubereiten? K{\"o}nnen wir mit unserem Mindset aus der Vergangenheit die ben{\"o}tigten {\"u}berfachlichen Kompetenzen f{\"u}r die Zukunft vermitteln? Diese selbstkritische Auseinandersetzung ist schmerzhaft, doch nur durch diese Analyse k{\"o}nnen wir unsere alten Denkmuster in engen Fachdisziplinen ablegen und zu einem neuen vernetzten Denken f{\"u}r eine zukunftsgerichtete Lehre kommen.}, language = {de} } @inproceedings{BlankBrunnerFuhrmannetal., author = {Blank, M. and Brunner, Stefan and Fuhrmann, Thomas and Meier, Hans and Niemetz, Michael}, title = {Embedded Linux in engineering education}, series = {2015 IEEE Global Engineering Education Conference (EDUCON), 18-20 March 2015, Tallinn, Estonia}, booktitle = {2015 IEEE Global Engineering Education Conference (EDUCON), 18-20 March 2015, Tallinn, Estonia}, publisher = {IEEE}, doi = {10.1109/EDUCON.2015.7095964}, pages = {145 -- 150}, abstract = {With the availability of cost effective embedded Linux solutions and the increasing complexity of embedded devices because of growing calculation power and communication demand, Linux is getting increasingly interesting as an operating system for the design of embedded control solutions. This is the case for almost all technical applications in electrical engineering like energy distribution systems, high level communication, signal processing or industrial automation. In the engineering master courses at the OTH Regensburg, a lecture is offered introducing students to Linux with a strong focus on embedded applications. This paper describes the concept of the lecture including the laboratory set up and gives some examples of embedded Linux projects performed by students.}, language = {en} } @article{NiemetzHaenninenSchoepe, author = {Niemetz, Michael and H{\"a}nninen, Risto and Schoepe, Wilfried}, title = {On the Transition from Potential Flow to Turbulence Around a Microsphere Oscillating in Superfluid 4He}, series = {Journal of low temperature physics}, volume = {187}, journal = {Journal of low temperature physics}, number = {3-4}, publisher = {Springer Nature}, doi = {10.1007/s10909-017-1745-7}, pages = {195 -- 220}, abstract = {The flow of superfluid around a translationally oscillating sphere, levitating without mechanical support, can either be laminar or turbulent, depending on the velocity amplitude. Below a critical velocity that scales as and is temperature independent below 1 K, the flow is laminar (potential flow). Below 0.5 K, the linear drag force is caused by ballistic phonon scattering that vanishes as until background damping, measured in the empty cell, becomes dominant for K. Increasing the velocity amplitude above leads to a transition from potential flow to turbulence, where the large turbulent drag force varies as . In a small velocity interval \% above , the flow is unstable below 0.5 K, switching intermittently between both patterns. From time series recorded at constant temperature and driving force, the lifetimes of both phases are analyzed statistically. We observe metastable states of potential flow which, after a mean lifetime of 25 min, ultimately break down due to vorticity created by natural background radioactivity. The lifetimes of the turbulent phases have an exponential distribution, and the mean increases exponentially with . We investigate the frequency at which the vortex rings are shed from the sphere. Our results are compared with recent data of other authors on vortex shedding by moving a laser beam through a Bose-Einstein condensate. Finally, we show that our observed transition to turbulence belongs to the class of "supertransient chaos" where lifetimes of the turbulent states increase faster than exponentially.}, language = {en} } @inproceedings{HaenninenNiemetzSchoepe, author = {H{\"a}nninen, Risto and Niemetz, Michael and Schoepe, Wilfried}, title = {Transition to turbulence in oscillatory superflows}, series = {ETC 2013 - 14th European Turbulence Conference 2020: 2 September 2013 - 4 September 2013, Lyon, France}, booktitle = {ETC 2013 - 14th European Turbulence Conference 2020: 2 September 2013 - 4 September 2013, Lyon, France}, abstract = {The flow of superfluid helium-4 at very low temperatures around an oscillating microsphere has been studied in detail. At small oscillation amplitudes the drag force is linear in velocity amplitude. Above a critical velocity amplitude vc a transition from potential flow to turbulent flow is signaled by a large and nonlinear drag force that scales as (v2 - v2 c ), where vc is found to be independent of temperature (below 1 K) and of driving force. Interestingly, the critical velocity is found to scale as vc ~ √κω, where κ = h/m ≈ 10-7 m2/s (h is Planck's constant and m is the mass of a helium-4 atom) is the circulation quantum of the superfluid vortices and ω/2π is the oscillation frequency ranging from about 120 Hz to 700 Hz. We also observe slightly above vc that the flow pattern is unstable and switches intermittently between potential flow and turbulence. From time series recorded at constant drive and temperature we have investigated the statistical properties of this switching phenomenon. In this talk the universal law vc ~ √κω will be discussed in detail. It can be derived theoretically in various ways: firstly, from a qualitative but very general argument based on the "superfluid Reynolds number" Rs = vl/κ where v is the flow velocity and l is a characteristic length scale, secondly, and in more detail, from Kopnin's equation of the time dependence of the vortex line density, and, finally, we have obtained this law rigorously by dynamical scaling of the equations of motion of vortex dynamics.}, language = {en} } @inproceedings{MeierReindlWetzeletal., author = {Meier, Hans and Reindl, Andrea and Wetzel, Daniel and Niemetz, Michael}, title = {Comparative Analysis of CAN, CAN FD and Ethernet for Networked Control Systems}, series = {Embedded World 2021 Exhibition \& Conference: 1.-5.3.2021, digital, conference proceedings}, booktitle = {Embedded World 2021 Exhibition \& Conference: 1.-5.3.2021, digital, conference proceedings}, publisher = {WEKA Fachmedien}, abstract = {Networked control systems as e.g., battery management systems, smart grids or vehicular systems, consist of sensors, actuators and controllers with a communication network in the control loop. The data rate and the reliability of the underlying communication network are key factors since delays or message losses directly affect the system control. In addition, the processor load caused by the communication is significant as it influences the calculation of system states and the setting of control parameters. The power consumption of the communication network has a further impact on the energy efficiency of the respective application. In this paper, the communication technologies Controller Area Network (CAN), Controller Area Network Flexible Data-rate (CAN FD) and Ethernet are compared in the context of networked control systems with focus on a decentralized battery management system. First, the message processing time and the processor load are measured. With regard to energy efficiency, the maximum power consumption is determined. The Bit Error Rates (BER) and the Residual Error Rates (RER) are calculated to evaluate the reliability. Finally, the receive FIFO load under high traffic conditions is examined. Index Terms—Networked control systems, decentralized battery management system, microcontrollers, communication systems, Ethernet, Controller Area Network (CAN), Controller Area Network Flexible Data-rate (CAN FD) energy efficiency, energy consumption, bit error rate, residual error rate, processor load.}, language = {en} } @inproceedings{KoernerReindlMeieretal., author = {K{\"o}rner, Patrick and Reindl, Andrea and Meier, Hans and Niemetz, Michael}, title = {A Theoretical Comparison of Different Virtual Synchronous Generator Implementations on Inverters}, series = {2022 24th European Conference on Power Electronics and Applications (EPE'22 ECCE Europe): 05-09 September 2022, Hannover, Germany}, booktitle = {2022 24th European Conference on Power Electronics and Applications (EPE'22 ECCE Europe): 05-09 September 2022, Hannover, Germany}, publisher = {IEEE}, pages = {9}, abstract = {The goal to overcome the global climate crisis leads to a rising demand for the usage of Renewable Energy Sources (RES). Decentralized control strategies are needed to allow the integration of RES into the grid. The Virtual Synchronous Generator (VSG) is proposed as a method to add virtual inertia to the grid by emulating the rotating mass of a Synchronous Generator (SG) on the control algorithm of an inverter. This paper presents the VSG control structure as well as the mathematical description in a unified form. Due to the fact that classical droop control can be seen as a special form of the VSG, their correlation is highlighted by evaluating the steady state output characteristics of the inverter. Furthermore, a theoretical comparison between different VSG topologies, including the VISMA-Method 2 and the synchronverter, is given. In order to achieve better voltage stability, principles to add virtual impedance to the inverter's output are described.}, language = {en} } @inproceedings{FuhrmannNiemetz, author = {Fuhrmann, Thomas and Niemetz, Michael}, title = {Ideas on Digitally Supported Individualization of Teaching and Learning for Evolving Competency Requirements}, series = {Ninth International Conference on Higher Education Advances (HEAd 23), Val{\`e}ncia, June 19, 2023 - June 22, 2023}, booktitle = {Ninth International Conference on Higher Education Advances (HEAd 23), Val{\`e}ncia, June 19, 2023 - June 22, 2023}, publisher = {Universitat Polit`ecnica de Val`encia}, issn = {2603-5871}, doi = {10.4995/HEAd23.2023.16232}, pages = {1399 -- 1406}, abstract = {The world is changing rapidly, mainly due to the digitalization of all areas of living. A huge amount of information is accessible via the Internet, and since it is no longer possible for individual humans to keep track of it, artificial intelligence (AI) is analyzing this data. In this rapidly changing world, students have to be educated for a successful career during their whole working life. These boundary conditions lead to completely new challenges for the education of students that are unprecedented in this form. Digitalization in education can help to cope with these challenges but can only be a means, not a goal. Personal interaction with students remains the most important task in education to address individual weaknesses and further develop strengths and talents. With the increasing amount of openly available information and the consequently increasing diversity of experiences within the group of students, differentiation is advancing to become the key to successful education. Digitization can help with this challenging task and support communication between students and their experienced instructors. But computers cannot replace human interaction and attempts to improve teaching efficiency by replacing this communication with electronic means endangers the learning success for complex concepts. This article analyzes education demands and possibilities for digitally supported teaching and learning.}, language = {en} } @inproceedings{ReindlWetzelNiemetzetal., author = {Reindl, Andrea and Wetzel, Daniel and Niemetz, Michael and Meier, Hans}, title = {Leader Election in a Distributed CAN-Based Multi-Microcontroller System}, series = {2023 3rd International Conference on Electrical, Computer, Communications and Mechatronics Engineering (ICECCME), 19-21 July 2023, Tenerife, Canary Islands, Spain}, booktitle = {2023 3rd International Conference on Electrical, Computer, Communications and Mechatronics Engineering (ICECCME), 19-21 July 2023, Tenerife, Canary Islands, Spain}, publisher = {IEEE}, address = {Piscataway, NJ, USA}, isbn = {979-8-3503-2297-2}, doi = {10.1109/ICECCME57830.2023.10252250}, pages = {1 -- 8}, abstract = {In a distributed system, functionally equivalent nodes work together to form a system with improved availability, reliability and fault tolerance. Thereby, the purpose is to achieve a common control objective. As multiple components cooperate to accomplish tasks, coordination between them is required. Electing a node as the temporary leader can be a possible solution to perform coordination. This work presents a self-stabilizing algorithm for the election of a leader in dynamically reconfigurable bus topology-based broadcast systems with a message and time complexity of O(1). The election is performed dynamically, i.e., not only when the leader node fails, and is criterion-based. The criterion used is a performance related value which evaluates the properties of the node regarding the ability to perform the tasks of the leader. The increased demands on the leader are taken into account and a re-election is started when the criterion value drops below a predefined level. The goal here is to distribute the load more evenly and to reduce the probability of failure due to overload of individual nodes. For improved system availability and reduced fault rates, a management level consisting of leader, assistant and co-assistant is introduced. This reduces the number of required messages and the duration in case of non-initial election. For further reduction of required messages to uniquely determine a leader, the CAN protocol is exploited. The proposed algorithm selects a node with an improved failure rate and a reduced message and hence time complexity while satisfying the safety and termination constraints. The operation of the algorithm is validated using a hardware test setup.}, language = {en} } @inproceedings{ReindlLausserErikssonetal., author = {Reindl, Andrea and Lausser, Florian and Eriksson, Lars and Park, Sangyoung and Niemetz, Michael and Meier, Hans}, title = {Control Oriented Mathematical Modeling of a Bidirectional DC-DC Converter - Part 1: Buck Mode}, series = {28th International Conference on Applied Electronics (AE) 2023, Pilsen, 6-7 September 2023}, booktitle = {28th International Conference on Applied Electronics (AE) 2023, Pilsen, 6-7 September 2023}, editor = {Pinker, Jiř{\´i}}, publisher = {University of West Bohemia}, address = {Pilsen}, isbn = {979-8-3503-3554-5}, doi = {10.1109/AE58099.2023.10274168}, pages = {1 -- 7}, abstract = {Parallel connection of different batteries equipped with bidirectional DC-DC converters offers an increase of the total storage capacity, the provision of higher currents and an improvement of reliability and system availability. To share the load current among the DC-DC converters while maintaining the safe operating range of the batteries, appropriate controllers are needed. The basis for the design of these control approaches requires knowledge of both the static and dynamic characteristics of the DC-DC converter used. In this paper, the small signal analysis of a DC-DC converter in buck mode is shown using the circuit averaging technique. The paper gives an overview of all required transfer functions:. The control and line to output transfer functions for CCM and DCM relevant for average current mode control as well as for voltage control are derived and their poles and zeros are determined. This provides the basis for stability consideration, analysis of the overall control structure and controller design.}, language = {en} } @inproceedings{FuhrmannNiemetz, author = {Fuhrmann, Thomas and Niemetz, Michael}, title = {Analysis and Improvement of Engineering Exams Toward Competence Orientation by Using an AI Chatbot}, series = {Towards a Hybrid, Flexible and Socially Engaged Higher Education: Proceedings of the 26th International Conference on Interactive Collaborative Learning (ICL2023), Volume 1}, booktitle = {Towards a Hybrid, Flexible and Socially Engaged Higher Education: Proceedings of the 26th International Conference on Interactive Collaborative Learning (ICL2023), Volume 1}, publisher = {Springer Nature}, address = {Cham}, isbn = {9783031519789}, issn = {2367-3370}, doi = {10.1007/978-3-031-51979-6_42}, pages = {403 -- 411}, abstract = {ChatGPT is currently one of the most advanced general chatbots. This development leads to diverse challenges in higher education, like new forms of teaching and learning, additional exam methods, new possibilities for plagiarism, and many more topics. On the other side with the development of advanced AI tools, pure knowledge will be less and less important, and demands from industry will change toward graduates with higher competencies. Education has therefore to be changed from knowledge-centered toward competence centered. The goal of this article is to use ChatGPT for analyzing and improving the competence orientation of exams in engineering education. The authors use ChatGPT to analyze exams from different engineering subjects to evaluate the performance of this chatbot and draw conclusions about the competence orientation of the tested exams. The obtained information is used to develop ideas for increasing the competence orientation of exams. From this analysis, it is visible that ChatGPT gives good performance mainly where knowledge is tested. It has, however, much more problems with transfer questions or tasks where students need creativity or complex insights for finding new solutions. Based on this result, exams and also lectures can be optimized toward competence orientation.}, language = {en} } @inproceedings{ReindlLangerMeieretal., author = {Reindl, Andrea and Langer, Tobias and Meier, Hans and Niemetz, Michael}, title = {Comparative Reliability Analysis for Single and Dual CAN (FD) Systems}, series = {27th 2022 International Conference on Applied Electronics (AE): 6-7 September 2022, Pilsen, Czech Republic}, booktitle = {27th 2022 International Conference on Applied Electronics (AE): 6-7 September 2022, Pilsen, Czech Republic}, publisher = {IEEE}, isbn = {9781665494816}, doi = {10.1109/AE54730.2022.9920078}, pages = {1 -- 6}, abstract = {Modern cyber-physical systems, such as autonomous vehicles, advanced driver assistance systems, automation systems and battery management systems, result in extended communication requirements regarding the reliability and the availability. The Controller Area Network (CAN) is a broadcast-based protocol which is still used as a standard for serial communication between individual microcontrollers due to its reliability and low power consumption. In addition, it provides mechanisms for detecting transmission errors and retransmitting messages in the event of an error. The enhancement CAN Flexible Data-Rate (CAN FD) offers increased data rates and transmission rates in order to meet the data throughput requirements. In this paper, the mechanisms for reliable data transmission in a CAN FD network are analyzed. To improve reliability, a second identical CAN-FD network is added to the system, using the additional CAN interface already available on common microcontrollers. The redundant communication network is examined in terms of failure rates and the mean time to failure. The reliability over the operation time is calculated for the single and the redundant version of the CAN FD network using the failure rate limits of the ASIL levels.}, language = {en} } @inproceedings{ReindlLangNiemetzetal., author = {Reindl, Andrea and Lang, Andreas and Niemetz, Michael and Meier, Hans}, title = {Switching and Averaging Models of a Bidirectional, Half-Bridge Based DC-DC converter with Load Distribution}, series = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, booktitle = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, publisher = {OJS}, doi = {10.3384/ecp204683}, abstract = {Batteries are used in numerous applications such as mobile devices, electric vehicles, home storage systems and islanded microgrids. Bidirectional DC-DC converters are vital for the integration of batteries, for the power conversion during (dis)charge and the battery management. Modeling of these is helpful, especially for the design of larger, more complex systems consisting of multiple DC-DC converters in parallel. Due to the high switching frequencies, the simulation of DC-DC converters is associated with increased computational time and effort. In this paper, three models of different complexity and accuracy are proposed for a bidirectional DC-DC converter consisting of two phase-shifted half-bridges. Two switching models, which differ mainly in the way the mosfets are driven, account for the individual switching operations and exhibit high accuracy. An averaging model replaces the switching elements with current and voltage sources providing the mean values. It is particularly suitable for multiple components and longer simulation durations. The dynamic behavior of the models is analyzed using the step responses of the load current. For validation, these are compared with the theoretical transfer function. The three models are analyzed comparatively in terms of computational time and effort. The calculation time of the averaging model has been reduced by two thirds compared to the strictly complementary switching model and by 96\% relative to the model with diode emulation mode. The averaging model requires only one third of the computation time of the complementary switching model and only 3.5\% of that of the model with diode emulation. Recommendations for the use of the models are given and a possible use case is shown. Two parallel connected DC-DC converters with load current sharing between them are simulated using the averaging model.}, language = {en} } @inproceedings{FuhrmannNiemetz, author = {Fuhrmann, Thomas and Niemetz, Michael}, title = {Fostering democratic attitude within engineering education}, series = {11th International Conference on Higher Education Advances (HEAd'25)}, booktitle = {11th International Conference on Higher Education Advances (HEAd'25)}, publisher = {Editorial Universitat Polit{\`e}cnica de Val{\`e}ncia (edUPV)}, address = {Valencia}, doi = {10.4995/HEAd25.2025.20093}, pages = {879 -- 886}, abstract = {According to the education ideal advocated by Wilhelm von Humboldt, education should be a holistic process to develop the whole human being and should not be narrowed toward job training. For example, in democratic societies, education should be directed to fostering a democratic mindset of students to strengthen pluralistic democracy. It is always possible to introduce a general course into a study program that deals with democratic education from a theoretical point of view. But by introducing such a course, the time spent on technical subjects will be reduced. The other major disadvantage of such solutions is that democratic education is seen to be separated from technical education. But in the contrary, democracy should be included in the whole life as a general way of thinking and cooperation between individuals. Therefore, ideas and lecture experiences are presented in this article on how democratic education can be integrated into all engineering subjects as an elementary educational design concept. Students should be led toward a general democratic attitude by practical application. To achieve this, democratic learning environments can be established in all types of courses like lectures, seminars, and labs. This includes, for example, the design of exercises, the presentation of the theoretical content, and the interaction between professors and students as well as the interaction between the students themselves as induced by the teaching activities. Also in exams, elements to promote democratic thinking are possible: Exams should be not directed to learning only content but toward understanding, creativity, and problem-solving competence. They should include, where possible, the fact that correct technical solutions are not unique but that a multiverse of solutions exists, with each solution featuring various strengths and weaknesses. This not only sensitizes the students for the need for (e.g. socially or environmentally) responsible technical design choices but also allows them to find optimized solutions for the engineering challenges at hand. In sum, lecturers should be aware that a democratic learning environment is a demanding process, as students must be taken as serious partners in a joint learning process and surprises are to be expected.}, language = {en} }