Jun.-Prof. Dr.-Ing. Sulamith Frerich
Institute of Thermo and Fluid Dynamics
- Enhancing Engineering Education by Virtual Laboratories: A Comparison Between Two Different Approaches
Keddi, D. and Frerich, S.
Advances in Intelligent Systems and Computing 1231 AISC (2021)The aim of this contribution is to compare two different settings of two virtual laboratories. Both of them are situated in the context of chemical engineering. One of them is used as online preparation for international students, while the other is implemented in lectures and seminars as demonstrating unit of subjects related to porous materials. While the online preparation for international students has already been at use, the demonstration unit is still work in progress. The students benefit from this kind of digital preparation to a high degree. Theoretical knowledge is available on an individual level, and they can choose time and place when to attend the courses. Many students mastered their course, understood the underlying concepts, and also exceeded usual expectations with their final reports. Regarding their comments, the implemented visualizations were highly appreciated, and the students also rated the set-ups as affirmative. However, a reasonable amount of participants complained about the absence of a real person in charge throughout the experiment, as they have experienced it in hands-on laboratories on site. Although it was found that virtual laboratories are an appropriate way to explain scientific topics, it can be observed that the actual implementation is still facing some issues. This contribution gives an overview of experiences made and discusses the potential for future applications of virtual laboratories in engineering education. © 2021, Springer Nature Switzerland AG.
view abstract 10.1007/978-3-030-52575-0_30
- How to Design Digitalized Laboratories?: Lessons Learned from Implementing Virtual and Remote Labs
Strenger, N. and Frerich, S.
Advances in Intelligent Systems and Computing 1231 AISC (2021)This contribution is showing ways to overcome issues on the way to digitalized laboratories in engineering education. The results presented in this paper were gained throughout a long-term study: 10 different laboratories were surveyed over a time period of 8 years. A non-standardized survey method was chosen for this evaluation, including a semi-structured guideline with open questions developed during several phases of pre-testing. The didactics and technical concepts of the laboratories are addressed, as well as challenges encountered during implementation and operation. Key findings of the whole study were identified by looking at didactical set-ups, technical aspects, and project managing topics. Although some aspects of hands-on experiments on-site were easily conveyed into virtual or remote laboratories, others needed to overcome severe impairments. However, personal commitment and financial support were identified as important success factors. By addressing original learning objectives as well as technical challenges that arose during set-up and digitalization of the laboratories, the results of this contribution clearly emphasize the connection between didactical purposes and technical realization. In some cases, both virtual and remote laboratories needed additional assistance in rephrasing learning objectives and adapting them throughout the process. © 2021, Springer Nature Switzerland AG.
view abstract 10.1007/978-3-030-52575-0_8
- Remote Lab meets Virtual Reality - Enabling immersive access to high tech laboratories from afar
Trentsios, P. and Wolf, M. and Frerich, S.
Procedia Manufacturing 43 (2020)Virtual Reality is currently one of the strongest trends in the consumer and gaming industry, while the typical Remote Lab in engineering education uses traditional 2D visualization options for desktop PCs. In this paper those two domains were combined by establishing state-of-the-art frontends for an existing engineering education Remote Lab. As the whole nature of this approach is experimental, the authors aimed at a variable degree of immersion and established two different approaches for the creation of a virtual environment. The first approach is to display the representation of the physical laboratory with 360°-images in a Street View type fashion. The second approach is a completely reconstructed virtual 3D-model of the existing physical laboratory. Both approaches were realized with the Unity engine and tested in the concerning laboratory. © 2020 The Authors. Published by Elsevier B.V.
view abstract 10.1016/j.promfg.2020.02.104
- Development of a method to measure the thermal conductivity of pressurised solutions containing dense gases using 11000 g/mol polydimethylsiloxane and carbon dioxide as example fluid
Lang, S. and Pollak, S. and Frerich, S.
Fluid Phase Equilibria 490 (2019)The development of a method to measure the thermal conductivity of mixtures containing pressurised gases is presented. As example fluid, we use carbon dioxide mixed with a linear polydimethylsiloxane (PDMS) with a molecular weight of 11000 g/mol. Experiments were carried out at 25 °C, 40 °C and 60 °C in a pressure range of up to 16 MPa. Thermal conductivity was measured in a high-pressure view cell using two different sensors: a cylindrical needle sensor and a short hot wire. Both sensors are based on the principle of a transient linear heat source. Their applicability was compared and evaluated. Rather low molecular weight polydimethylsiloxane was chosen as model substance to close the data gap regarding the thermal conductivity of gas saturated solutions, pressurised with carbon dioxide. All experiments were carried out under isothermal conditions. It was the aim of the present work to develop and to test an adequate measuring instrument; this involves the selection and implementation of appropriate auxiliary equipment, too. © 2019 Elsevier B.V.
view abstract 10.1016/j.fluid.2019.03.005
- Framework for Augmented Reality Scenarios in Engineering Education
Neges, M. and Wolf, M. and Kuska, R. and Frerich, S.
Lecture Notes in Networks and Systems 47 (2019)The goal of the presented approach is to show a method suitable for better integration of real-time sensor data into practical education, without leaving the students to sort out the digital content by themselves. The authors want to empower teachers on-site to show their students relevant sensory data, effectively controlling the content the students can use and explore themselves. The students are enabled to find individual approaches towards the learning scenario, take different perspectives of the plant into account and try several virtual steps before the experiment is undertaken by themselves. The two main functions of the presented framework are the authoring of augmented reality content and controlling the augmented reality content of the student’s smart devices via the teacher’s master view. The authors created a simple setup phase, which is usable on-site, utilizing only one device in the master view mode. For students, the usage is even simpler, as their content is controlled via the master view. The framework technically supports an unlimited number of student clients to be controlled by one teacher view. The functionality has been established and validated with two experimental setups, both situated within the context of chemical engineering education. © 2019, Springer International Publishing AG, part of Springer Nature.
view abstract 10.1007/978-3-319-95678-7_68
- Solubility of pressurised carbon dioxide in three different polydimethylsiloxanes
Lang, S. and Frerich, S. and Pollak, S.
Fluid Phase Equilibria 491 (2019)We present an experimental investigation into the binary phase behaviour of carbon dioxide and three different linear polydimethylsiloxanes (PDMS) with molecular weights of 4800 g/mol, 11000 g/mol and 18000 g/mol. Experiments were carried out at 25 °C, 40 °C and 60 °C and at pressures of up to 30 MPa. Solubilities were measured with the help of a high pressure view cell using two different techniques, the observation of cloud points, and a static analytic method based on sampling under phase equilibrium conditions. Rather low molecular weight polydimethylsiloxanes were chosen to close the existing data gap regarding the behaviour of these compounds with carbon dioxide. All experiments in the present work were carried out under isothermal conditions. Hence, diagrams of the p-x type are used for displaying the measured data at constant temperatures. © 2019 Elsevier B.V.
view abstract 10.1016/j.fluid.2019.03.009
- Supercritical CO 2 - assisted production of PLA and PLGA foams for controlled thymol release
Milovanovic, S. and Markovic, D. and Mrakovic, A. and Kuska, R. and Zizovic, I. and Frerich, S. and Ivanovic, J.
Materials Science and Engineering C 99 (2019)Amorphous, medical grade poly(D,L-lactic acid) (PLA) and poly(D,L-lactic-co-glycolic acid) (PLGA) were used to develop systems for controlled release of a natural bioactive substance - thymol. Supercritical carbon dioxide (scCO 2 ) was successfully used both as an impregnation medium for thymol incorporation into the polymer matrix and a foaming agent in a single-step batch process. Impregnation of samples using low to moderate scCO 2 densities (273 kg/m 3 and 630 kg/m 3 ) and short processing times (2 h and 4 h) enabled thymol loading of 0.92%–6.62% and formation of microcellular foams upon system depressurization. Thymol effect on structural and thermal properties on foamed samples was proven by FTIR and DSC. The effect of CO 2 under elevated pressure on the neat polymers was analysed by high pressure DSC. Foaming of polymers with lower molecular weight by CO 2 of higher density yielded foams with smaller pores. All tested foams released thymol in a controlled manner in phosphate buffered saline (PBS) at 37 °C within 3 to 6 weeks. Higher loading and lower cell density favoured thymol release rate, while its concentration in PBS for the tested period depended on foam interaction with the medium. Representative PLGA foam sample with the highest thymol loading (6.62%) showed controlled thymol release within 72 h in mediums having pH values from 1.1 to 7.4. © 2019 Elsevier B.V.
view abstract 10.1016/j.msec.2019.01.106
- Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design
Kuska, R. and Milovanovic, S. and Frerich, S. and Ivanovic, J.
Journal of Supercritical Fluids 144 (2019)Thermal properties of extrusion and injection grade polylactic acid (PLA) were analysed using high pressure differential scanning calorimetry (HP-DSC) under CO2 pressures of up to 50 MPa. The greatest depression of melting point and degree of crystallinity of the samples occurred at 20–30 MPa (∼97–115 °C). Batch and semi-continuous processes for supercritical foaming and impregnation of PLA with thymol or thyme extract were performed at 30 MPa and 100–110 °C to prevent thymol degradation, decrease heating requirements and ease polymer processing. At these conditions, PLA foams containing 5.6% or 1.1% of thymol and 0.7% of thyme extract were obtained using static or dynamic batch impregnation and semi-continuous extraction-impregnation process for 7 h, respectively. DSC and HP-DSC analyses revealed more pronounced effect of scCO2 plasticizing than foaming on PLA crystallinity. Neat and impregnated PLA foams with pores size of 15-200 μm have potential for food packaging, biomedical and insulation applications. © 2018 Elsevier B.V.
view abstract 10.1016/j.supflu.2018.10.008
- Special Issue - 15th European meeting on supercritical Fluids
Petermann, M. and Weidner, E. and Frerich, S. and Kareth, S. and Kilzer, A. and Pollak, S.
Journal of Supercritical Fluids 132 (2018)
view abstract 10.1016/j.supflu.2017.10.031
- Supercritical CO2 impregnation of PLA/PCL films with natural substances for bacterial growth control in food packaging
Milovanovic, S. and Hollermann, G. and Errenst, C. and Pajnik, J. and Frerich, S. and Kroll, S. and Rezwan, K. and Ivanovic, J.
Food Research International 107 (2018)Biodegradable polymers with antibacterial properties are highly desirable materials for active food packaging applications. Thymol, a dietary monoterpene phenol with a strong antibacterial activity is abundant in plants belonging to the genus Thymus. This study presents two approaches for supercritical CO2 impregnation of poly(lactic acid)(PLA)/poly(ε-caprolactone)(PCL) blended films to induce antibacterial properties of the material: (i) a batch impregnation process for loading pure thymol, and (ii) an integrated supercritical extraction-impregnation process for isolation of thyme extract and its incorporation into the films, operated in both batch or semi-continuous modes with supercritical solution circulation. The PCL content in films, impregnation time and CO2 flow regime were varied to maximize loading of the films with thymol or thyme extract with preserving films’ structure and thermal stability. Representative film samples impregnated with thymol and thyme extract were tested against Gram (−) (Escherichia coli) and Gram(+) (Bacillus subtilis) model strains, by measuring their metabolic activity and re-cultivation after exposure to the films. The film containing thymol (35.8 wt%) showed a strong antibacterial activity leading to a total reduction of bacterial cell viability. Proposed processes enable fast, controlled and organic solvent-free fabrication of the PLA/PCL films containing natural antibacterial substances at moderately low temperature, with a compact structure and a good thermal stability, for potential use as active food packaging materials. © 2018 Elsevier Ltd
view abstract 10.1016/j.foodres.2018.02.065
- GoING.ábroad:: A discipline-specific approach to promote the mobility of German engineering students
Strenger, N. and Petermann, M. and Frerich, S.
IEEE Global Engineering Education Conference, EDUCON (2017)The GoING Abroad program was designed by the project ELLI - Excellent Teaching and Learning in Engineering Science - at the Ruhr Universität Bochum in Germany in order to increase the international mobility of engineering students. A regular information session combines subject-specific information with student experiences and introduces contact persons at the university and engineering faculties. The format is accompanied by information material such as a newsletter, a website and a brochure. Starting in spring 2013, over 350 students have participated in the sessions and subscribed to the newsletter. This short paper explains the special requirements and according setup of a program that aims at increasing outbound mobility by encouraging engineering students to spend a study semester or an internship abroad. It shows how different stakeholders in internationalization can be brought together with a common objective to reduce mobility barriers and to distribute outgoing placements efficiently among students. It gives an overview of participation structure and evaluation results of the 9 info sessions conducted during the last four years. The program's overall performance will be considered as well as its acceptance among students and faculty employees. © 2017 IEEE.
view abstract 10.1109/EDUCON.2017.7942852
- Remote labs in ELLI: Lab experience for every student with two different approaches
Kruse, D. and Frerich, S. and Petermann, M. and Ortelt, T.R. and Tekkaya, A.E.
IEEE Global Engineering Education Conference, EDUCON 10-13-April-2016 (2016)With the goal of extending the possibilities for practical experience in engineering tasks, the project ELLI (Excellent Teaching and Learning in Engineering Sciences) follows the idea of providing virtual and remote labs for students, teachers and even interested people from different disciplines, countries or skill levels. To integrate these labs into the existing curriculum and to get students and teachers used to this tool are challenging processes. Moreover, the technical development of the remote labs is as much important as the integration to an e-learning environment. Two different approaches for the development and the integration are described. © 2016 IEEE.
view abstract 10.1109/EDUCON.2016.7474595
- Biopolymer foaming with supercritical CO2 - Thermodynamics, foaming behaviour and mechanical characteristics
Journal of Supercritical Fluids 96 (2015)Polymer foams, especially those based on biodegradable polymers, are in high demand for energy saving applications, for example as thermal insulations or packaging materials. To understand and predict the quality and material properties of polymer foams, concise knowledge of the factors influencing the foaming behaviour, especially pressure and temperature, is required. Therefore, three biodegradable polyesters, namely poly (lactide) (PLA), poly (butylene succinate) (PBS) and a blend of poly (lactide) and poly (hydroxy butyrate) (PLA-PHB), have been subjected to a direct foaming procedure using compressed carbon dioxide as blowing agent, studying the influence of saturation temperature (ranging from 95 °C to 175°C) and applied pressure (ranging from atmospheric pressure to 30 MPa) on the resulting foam material. As these results are strongly depending on the melting behaviour of the polymers, all three polymers were subjected to calorimetric analysis in a scanning transitiometer that allows for applying pressure levels of up to 45 MPa. The created porous materials were characterized by determining their density, porosity and morphology, using SEM analysis. Their mechanical behaviour was investigated by using compressive strength tests. It is shown that the quality of the produced foam structures and its properties is strongly depending on the foaming conditions. In order to obtain foams with a high quality, the saturation temperature and pressure have to be adapted to the phase transition liquid-solid of the polymer-gas system. The results obtained via scanning transitiometer represent the SLG-line of the binary systems polymer and CO2, and their influence on the foaming behaviour enabled the identification of ideal foaming conditions for the three polymers regarded in this study. © 2014 Elsevier B.V. All rights reserved.
view abstract 10.1016/j.supflu.2014.09.043
- Retaining talent, addressing diverse requirements: Academic writing for engineering students
Janssen, T. and Strenger, N. and Frerich, S. and Peters, F.
IEEE Global Engineering Education Conference, EDUCON 2015-April (2015)In the light of the anticipated and much-discussed shortage of skilled labor and university graduates in the STEM fields, attracting students for technological studies is an important strategic aim of German universities and engineering faculties. Currently, the so-called 'doppelter Abiturjahrgang' (a result of reducing school years from 13 to 12) plays into their hands by releasing twice the amount of high school graduates into the study and work market in Germany. Still, dropout rates among students of engineering sciences are higher than in other subject fields and, consequently, universities and employers are losing potential engineering graduates despite the fact that the total number of enrollments increased. Among the factors considered to be responsible for university dropout are lacks of social and academic integration. Furthermore, formats such as mass lectures that are often part of undergraduate studies in engineering prevent teaching approaches that deal with individual requirements of students. However, a more individual approach is what the increasing diversity among university students would call for. Against the backdrop of an increasingly heterogeneous student body, academic writing presents one of the biggest challenges in engineering studies. In order to support students during their first semesters but also in writing their final theses, the project ELLI is currently implementing a multi-level concept to foster academic writing in engineering studies. At the Ruhr-University Bochum, quantitative and qualitative research was done among students and faculty members of the three engineering faculties, based on which a guidebook for writing final theses was developed. Moreover, a seminar for academic writing for undergraduate engineering students was designed, which will take place for the first time in the winter term of 2014. © 2015 IEEE.
view abstract 10.1109/EDUCON.2015.7095945
- Student exchange programs in engineering sciences between USA and Germany
Strenger, N. and Petermann, M. and Frerich, S.
IEEE Global Engineering Education Conference, EDUCON (2014)In the Unites States of America (USA), as well as in Germany, the international mobility of students in engineering sciences is rather low in comparison to students of other disciplines. While the USA are the most attractive host country for German engineering students, American students' interest in coming to Germany is not equally great. Facing different teaching languages and semester times, summer school formats seem to be a good solution for German universities to attract students from the USA. However, summer schools might not always be the most suitable way of providing possibilities for the development of international skills. At the Ruhr University Bochum, the project ELLI works on the further development of student exchange programs in engineering education. This short paper represents work in progress. It gives an overview of the context of student exchange in and between the USA and Germany and describes the results of one case study that was made in Bochum. © 2014 IEEE.
view abstract 10.1109/EDUCON.2014.6826233
- Virtual Labs and Remote Labs: Practical experience for everyone
Frerich, S. and Kruse, D. and Petermann, M. and Kilzer, A.
IEEE Global Engineering Education Conference, EDUCON (2014)Laboratory experiences should be available for a great number of students in engineering education, especially at times when the number of students is even more increasing. Virtual Labs and Remote Labs are innovative tools used for improvement. They are either simulating experiments (Virtual Labs) or remotely operated plants (Remote Labs). At Ruhr-University Bochum, the implementation of eight new labs was supported by the project ELLI (excellent teaching and learning in engineering sciences). Didactical concepts as well as sustainable implementations were among the criteria of the independent jury's decision. After their setup, the management of the variety of labs is the next step. This short paper reports the work in progress in the year 2013, the whole process is to be continued and improved. © 2014 IEEE.
view abstract 10.1109/EDUCON.2014.6826109
virtual and remote labs