| 1. |
- Stöhr, Christian, 1977, et al.
(författare)
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Online and Blended Labs for Practical Mechanical Engineering
- 2023
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Ingår i: Proceedings of the 19th International CDIO Conference. - 9788230361863 ; , s. 805-819
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Konferensbidrag (refereegranskat)abstract
- Lab training is a key element in most engineering education programs in preparation for engineering profession tasks. Universities worldwide are exploring new possibilities and different forms to arrange online and blended labs as an alternative to pure campus training. This study compares online and blended lab setups in four cases of engineering education at European technical universities. The results show that online and blended labs can achieve similar learning outcomes, with blended labs being particularly effective in combining online learning with hands-on elements. Students reported high levels of satisfaction and teachers noted the benefits of online learning environments, but common challenges included ensuring student engagement, increased self-regulation requirements, and the high effort needed to design online or blended environments. The study provides course design guidelines and discusses implications for future research and implementation in universities worldwide.
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| 2. |
- Langer, Patrick, et al.
(författare)
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Simplification of complex structural dynamic models : A case study related to a cantilever beam and a large mass attachment
- 2021
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Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- Large attachments can dramatically affect the dynamic response of an assembled structure. In various industrial sectors, e.g., the automotive, aircraft, and shipbuilding industries, it is often necessary to predict the dynamic response of assembled structures and large attachments in early-stage engineering design. To deal with this, it is often the finite element method (FEM) that is used in the vibrational analysis. Despite the advent of large-scale computer availability, it is still common-place, and often necessary, to reduce the model-size with large attachments to acceptable levels for computer time-scale or memory-size limitations. This article discusses the simple methodology of replacing large and sometimes complicated attachments by using a simplified boundary condition. This methodology is well-known in certain sectors of computer-aided design, but here we are able to present a comprehensive discussion from laboratory measurements, finite element analysis and a simplified perspective. Given the availability of experimental data, the errors produced by these methodologies may then be determined by a structure that has a strictly defined geometry and known material properties within a certain tolerance. To demonstrate these effects, an experimental modal analysis is performed on a structure consisting of a beam and a large mass attachment, which is then validated by each of the finite element models that include the relevant approximate ideal boundary conditions. Various approximating boundary conditions are investigated, and quantifiable results are discussed. One of the conclusions confirms the recommendation that rotary inertia terms should be included as a boundary condition wherever possible when large attachments are approximated by an offset mass defined at a point.
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| 3. |
- Lygnerud, Kristina, et al.
(författare)
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Handbook for increased recovery of urban excess heat
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this book is to consolidate information from low temperature waste heat recovery demonstration sites. Apart from technical validation, the ReUseHeat project has generated knowledge about the urban waste heat potential in Europe, main stakeholders and different business aspects. Five stakeholder groups are targeted. These are urban waste heat owners, District Heating (DH) companies, policy makers, investors and customers. In the first chapter of the book, the concept of urban waste heat is introduced and the urban waste heat potential in Europe is presented. Thereafter (chapter two), information on business aspects is provided (stakeholders, value chain, risks, contracts and business model characteristics). Chapter three showcases the demonstrator concepts (waste heat recovery from data centre, hospital, metro and awareness creation about urban waste heat recovery) and performance data. Throughout the writing of the handbook, it was identified that it is important to compare the cost of different heating alternatives, to facilitate customer decision making. Therefore, a model was derived to compare costs of heating alternatives. It is presented in chapter four. Urban waste heat recovery is news. It is therefore important that stakeholders are made aware of the possibility to use the locally available heat and to start collaborating in new ways. To ensure as much stakeholder engagement as possible, the writing process of this book encompassed a six-month stakeholder involvement process. The stakeholder input is presented in chapter five. In chapter six, thoughts on the future development of district energy, policy implications and major learnings from the project are presented. This book was written within the ReUseHeat project. The work on the book was initiated after the first out of five years of activity to ensure that the consortium would be engaged in its development and to capture the knowledge generated on an ongoing basis. The final version of the book was ready and placed on the ReUseHeat webpage in September 2022. The project webpage remains in operation until 2024. The book not only exists in digital format. 600 copies were also printed and distributed to relevant stakeholders. All partners of the consortium have contributed to the writing of the book.
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| 4. |
- Salvador, Christian Mark, 1989, et al.
(författare)
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Indoor ozone/human chemistry and ventilation strategies
- 2019
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Ingår i: Indoor Air. - : Hindawi Limited. - 1600-0668 .- 0905-6947. ; 29:6, s. 913-925
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to better understand and quantify the influence of ventilation strategies on occupant-related indoor air chemistry. The oxidation of human skin oil constituents was studied in a continuously ventilated climate chamber at two air exchange rates (1 h-1 and 3 h-1 ) and two initial ozone mixing ratios (30 and 60 ppb). Additional measurements were performed to investigate the effect of intermittent ventilation ("off" followed by "on"). Soiled t-shirts were used to simulate the presence of occupants. A time-of-flight-chemical ionization mass spectrometer (ToF-CIMS) in positive mode using protonated water clusters was used to measure the oxygenated reaction products geranyl acetone, 6-methyl-5-hepten-2-one (6-MHO) and 4-oxopentanal (4-OPA). The measurement data were used in a series of mass balance models accounting for formation and removal processes. Reactions of ozone with squalene occurring on the surface of the t-shirts are mass transport limited; ventilation rate has only a small effect on this surface chemistry. Ozone-squalene reactions on the t-shirts produced gas-phase geranyl acetone, which was subsequently removed almost equally by ventilation and further reaction with ozone. About 70% of gas-phase 6-MHO was produced in surface reactions on the t-shirts, the remainder in secondary gas-phase reactions of ozone with geranyl acetone. 6-MHO was primarily removed by ventilation, while further reaction with ozone was responsible for about a third of its removal. 4-OPA was formed primarily on the surfaces of the shirts (~60%); gas-phase reactions of ozone with geranyl acetone and 6-MHO accounted for ~30% and ~10%, respectively. 4-OPA was removed entirely by ventilation. The results from the intermittent ventilation scenarios showed delayed formation of the reaction products and lower product concentrations compared to continuous ventilation.
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| 5. |
- Sheikhi, Shahram, et al.
(författare)
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Blended Laboratories for Joining Technology
- 2023
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Ingår i: Proceedings of the International CDIO Conference. - 2002-1593. ; , s. 166-178
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Konferensbidrag (refereegranskat)abstract
- Laboratory training is an essential part of most Engineering Education programs and amplified by the Covid-19 crisis, educational institutions are increasingly exploring blended and online laboratories as an alternative or complement to pure on-side learning environments. In this paper, we report on the (re-) design, implementation and evaluation of a blended laboratory concept in joining technology. The laboratory consists of three interlinked pillars and builds conceptually on the flipped classroom approach. We evaluate student learning and satisfaction as well as teacher experiences in the new learning design based on student evaluations and performance data as well as teacher reflections. The results show that the new laboratory improved the average grade of students by 12% compared to the traditional set-up, which we attribute to the increase in active learning. Students also report high satisfaction with the new format and appreciate the flexibility and accessibility of the online learning materials. Qualitative analysis indicates, however, that successful participation in the flipped format is coupled to high degree of self-regulated learning skills. Further, teachers partly had difficulties to ensure active participation in the synchronous online sessions. Despite these issues, we conclude that the presented flipped laboratory concept is an excellent format to combine the advantages of online learning with the hands-on experience of physical laboratory work. By utilizing the benefits of online learning, this format reduces the time students spend passively listening to lectures and more than doubles the time spent on active learning and practice.
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| 6. |
- Langer, Judith, et al.
(författare)
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Present and Future of Surface-Enhanced Raman Scattering
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 14:1, s. 28-117
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Forskningsöversikt (refereegranskat)abstract
- The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article. ©
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