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Andersson, M., Karlander, J., Sandberg, M. & Tibert, G. (2023). Admission to master programmes: What are the indicators for successful study performance?. In: Joel Midemalm, Amir Vadiee, Elisabeth Uhlemann, Fredrik Georgsson, Gunilla Carlsson-Kvarnlöf, Jonas Månsson, Kristina Edström, Lennart Pettersson och Pedher Johansson (Ed.), Bidrag från den 9:e utvecklingskonferensen för Sveriges ingenjörsutbildningar: . Paper presented at 9:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar (pp. 9-18). Västerås: Mälardalens universitet
Open this publication in new window or tab >>Admission to master programmes: What are the indicators for successful study performance?
2023 (English)In: Bidrag från den 9:e utvecklingskonferensen för Sveriges ingenjörsutbildningar / [ed] Joel Midemalm, Amir Vadiee, Elisabeth Uhlemann, Fredrik Georgsson, Gunilla Carlsson-Kvarnlöf, Jonas Månsson, Kristina Edström, Lennart Pettersson och Pedher Johansson, Västerås: Mälardalens universitet, 2023, p. 9-18Conference paper, Published paper (Refereed)
Abstract [en]

Admission of applicants to higher education in a fair, reliable, transparent, and efficient way is a real challenge, especially if there are more eligible applicants than available places and if there are applicants from many different educational systems. Previous research on best practices for admission to master’s programmes identified the key question about an applicant’s potential for success in studies, but was not able to provide an answer about how to rate the merits of the applicants. In this study, indicators for study success are analysed by comparing the study performance of 228 students in master’s programmes with their merits at the time of admission. The null hypothesis was that the applicant’s average grade at the time of admission is the only indictor for study success. After testing for potential bias using almost 20 possible other indicators, the null hypothesis had to be rejected for four indicators (in order of importance): (i) university ranking, (ii) length of bachelor’s studies within subject, (iii) English language test and (iv) subject matching between bachelor’s and master’s education. Evaluation of quality of prior education is tricky and results from this study clearly indicate that students from higher ranked universities possess better knowledge and stronger skills for our master’s programmes. Work is ongoing to improve the merit rating model by involving more master’s programmes at KTH and analysing performance data from a larger number of students.

Place, publisher, year, edition, pages
Västerås: Mälardalens universitet, 2023
Keywords
Master, admission, merit rating model, success indicators
National Category
Educational Sciences
Identifiers
urn:nbn:se:kth:diva-343154 (URN)
Conference
9:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar
Note

QC 20240209

Part of ISBN 978-91-7485-620-0

Available from: 2024-02-08 Created: 2024-02-08 Last updated: 2024-02-09Bibliographically approved
Griffin, D. & Tibert, G. (2022). Cislunar Orbital Transportation Study of Space Elevator Apex Anchor Releases. In: 73rd International Astronautical Congress, IAC 2022: . Paper presented at 73rd International Astronautical Congress, IAC 2022, Paris, France, Sep 18 2022 - Sep 22 2022. International Astronautical Federation, IAF
Open this publication in new window or tab >>Cislunar Orbital Transportation Study of Space Elevator Apex Anchor Releases
2022 (English)In: 73rd International Astronautical Congress, IAC 2022, International Astronautical Federation, IAF , 2022Conference paper, Published paper (Refereed)
Abstract [en]

As humans increasingly begin to expand beyond the threshold of Low Earth Orbit (LEO), moving supplies and astronaut safety within the vastness of space can become daunting. Limited by Tsiolkovsky's Rocket Equation, rockets are inefficient at moving material off planet as only a small percentile of the rocket's launch pad mass reaches orbital space. While commercial enterprises have greatly increased the rate of rocket launches, a human emergency occurring far from Earth raises the question of how to send aid. Space Elevators are an additional solution to overcoming the initial constraints posed by rockets. In a simplified manner, a Space Elevator is a permanent infrastructure for moving large elevators (climbers) along a tether that extends from the surface of the Earth into space. This research looks at the volume of space between Earth and the Moon, otherwise known as Cislunar Space, and the benefits that a Space Elevator would contribute. Specifically, a safety for astronauts beyond LEO by means of the Apex Anchor (space station located at the top of the Space Elevator) as well as mass distribution to the Moon by means of the Space Elevator. Mathematical and engineering details for the Space Elevator's construction or orbits for payloads are referenced but not calculated in this study.

Place, publisher, year, edition, pages
International Astronautical Federation, IAF, 2022
Keywords
Astronaut safety, Cislunar space, Mass transportation, Space Elevator
National Category
Aerospace Engineering Astronomy, Astrophysics and Cosmology Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-335054 (URN)2-s2.0-85167627800 (Scopus ID)
Conference
73rd International Astronautical Congress, IAC 2022, Paris, France, Sep 18 2022 - Sep 22 2022
Note

QC 20230831

Available from: 2023-08-31 Created: 2023-08-31 Last updated: 2023-08-31Bibliographically approved
Matija, M., Mao, H., Tibert, G. & Dadbakhsh, S. (2022). Design and Development of Damping SandwichPanels for Satellite Housing Using AdditiveManufacturing. In: : . Paper presented at International Conference on Design for 3D Printing.
Open this publication in new window or tab >>Design and Development of Damping SandwichPanels for Satellite Housing Using AdditiveManufacturing
2022 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The present work investigates the performance of additively-manufactured sandwich structures with the goal of reducing the effect of vibrations on a spacecraft during launch, whilst minimizing mass. Additive manufacturing allows designers to implement custom and complex geometries, such as the sheet gyroid structures, inside sandwich panels. Accordingly, this work details the development of gyroid-based sandwich structures for damping. Several test specimens are designed, additively manufactured using ABS plastic, and their damping performances are evaluated based on both simulation and experiments. Damping values are identified using frequency response transfer functions. The results show that as theory predicts, adding more mass, through the added thickness of the gyroid reduces the amplitude of vibrations. However, on a damping-per-unit-mass basis, the experimental results are inconclusive mainly due to the measurements of vibrations in the center of the sandwich panels instead of the sides where the vibrations can be maximum. Therefore, simulations better illustrate the changes of the damping behavior at different applied frequencies. Lessons and experiences are summarized for future work, particularly in exploring the effects of varying other 3D printed composite meta-lattice sandwich structures for satellites. 

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-323991 (URN)
Conference
International Conference on Design for 3D Printing
Note

QC 20230220

Available from: 2023-02-17 Created: 2023-02-17 Last updated: 2023-02-27Bibliographically approved
Magnell, M., Delin, C., Rosén, A., Jerbrant, A., Tibert, G. & Casanueva, C. (2022). Integrating Gender Equality, Diversity, and Equal Conditions, in Engineering Education. In: Proceedings of the 18 th International CDIO Conference, hosted by Reykjavik University, Reykjavik Iceland, June13-15, 2022.: . Paper presented at 18th International CDIO Conference, Reykjavik Iceland, June 13-15, 2022.. Chalmers University of Technology
Open this publication in new window or tab >>Integrating Gender Equality, Diversity, and Equal Conditions, in Engineering Education
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2022 (English)In: Proceedings of the 18 th International CDIO Conference, hosted by Reykjavik University, Reykjavik Iceland, June13-15, 2022., Chalmers University of Technology , 2022Conference paper, Published paper (Refereed)
Abstract [en]

In engineering education, as well as in the society at large, there is an increasing focus on sustainability and sustainable development. The CDIO Standards and the CDIO Syllabus has been substantially updated to meet and drive these changes. Progressive engineering programs have by now made substantial progress in integrating environmental aspects of sustainability and sustainable development into the curriculum. However, the integration of social aspects is generally considered to be more difficult and is therefore lagging behind. This explorative research paper provides insights in efforts to integrate elements of gender equality, diversity and equal conditions (GDE) in three courses on bachelor’s, master’s, and doctoral level. The focus is on the development and implementation of reflective assignments, where a theoretical framework is used for characterizing different levels of reflection. The work has been performed by use of an action research approach that has involved close dialogue and collaboration between researchers, pedagogic developers, teachers, students, and education leaders. The paper hereby contributes with multiple perspectives on GDE integration, and significant challenges are discussed. The paper also contributes with concrete examples of reflective assignments, learning activities, and literature that can be useful also in other contexts.

Place, publisher, year, edition, pages
Chalmers University of Technology, 2022
Keywords
Gender equality, Diversity, Equal conditions, Sustainable development, Reflective writing, Optional standards for sustainable development, Standards: 1, 2, 3, 7, 11
National Category
Learning
Identifiers
urn:nbn:se:kth:diva-316353 (URN)2-s2.0-85145927185 (Scopus ID)
Conference
18th International CDIO Conference, Reykjavik Iceland, June 13-15, 2022.
Note

Part of ISBN 9789935965561

QC 20220818

Available from: 2022-08-16 Created: 2022-08-16 Last updated: 2023-08-14Bibliographically approved
Shahryarifard, M., Golzar, M. & Tibert, G. (2021). Toward thermal stimulation of shape memory polymer composite bistable tape springs. Smart materials and structures, 30(2)
Open this publication in new window or tab >>Toward thermal stimulation of shape memory polymer composite bistable tape springs
2021 (English)In: Smart materials and structures, ISSN 0964-1726, E-ISSN 1361-665X, Vol. 30, no 2Article in journal (Refereed) Published
Abstract [en]

Due to their tailored thermomechanical behavior and functionality, shape memory polymer matrix composites (SMPCs) are attractive as deployable structures in aerospace applications. An analytical model based on the classical laminate theory, together with the principle of minimum potential energy is developed to capture the thermo- viscoelastic behavior of a bistable tape spring (BiTS). These tape springs are known to snap between two stable configurations by different stimulus. Here, a shape memory polymer as the matrix of a fiber-reinforced polymer BiTS is introduced to actuate the snap-back. Experimental characterization was performed to obtain the time-temperature dependent properties of a Polyurethane SMPC. The time-temperature superposition principle was employed to convert the thermal effects to a viscoelastic response. Five BiTSs were manufactured and exposed to two different thermo-viscoelastic cycles to verify the model for long-term and high-temperature behaviors. The results show that the model can estimate the coiling radius and the degree of stability of the BiTS in the coiled configuration. Analytical results, supported by experimental results, show that the temperature could initiate the snap-back in BiTS. However, time-temperature history has a significant effect on the bistability and can convert a monostable tape spring to a BiTS and vice versa.

Place, publisher, year, edition, pages
IOP Publishing, 2021
National Category
Applied Mechanics Composite Science and Engineering
Research subject
Materials Science and Engineering; Aerospace Engineering
Identifiers
urn:nbn:se:kth:diva-290186 (URN)10.1088/1361-665X/abd342 (DOI)000607947800001 ()2-s2.0-85100332549 (Scopus ID)
Note

QC 20210215

Available from: 2021-02-13 Created: 2021-02-13 Last updated: 2024-02-12Bibliographically approved
Shahryarifard, M., Golzar, M. & Tibert, G. (2021). Viscoelastic bistable tape spring behavior modeled by a two-dimensional system with rigid links, springs and dashpots. Composite structures, 258, Article ID 113181.
Open this publication in new window or tab >>Viscoelastic bistable tape spring behavior modeled by a two-dimensional system with rigid links, springs and dashpots
2021 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 258, article id 113181Article in journal (Refereed) Published
Abstract [en]

Bistable composite tape springs are often used as deployable structures in aerospace applications because of their ability to be tailored for compact size, deployed lengths and stiffness. Analytical studies of the coupling between stress-strain and moment-curvature of thin curved shells have been used to estimate the total stored strain energy in different tape spring configurations. The strain energy as function of the curvatures reveals the fundamental stability behavior of the tape springs in the different configurations. The present study investigates the minimum strain energy path between two stable equilibrium points and the passage through the unstable saddle point along this path. For a coiled fiber reinforced composite tape spring, the strain energy level for the local minimum and the saddle points will change with respect to time due to viscoelastic effects. To explain the fundamental mechanical behavior of viscoelastic bistable tape springs, a two-dimensional (2D) model composed of rigid links, elastic springs and viscous dampers was proposed. It was shown how the 2D model can be made strain energy-equivalent to a shell model with respect to the minimum strain energy paths. The 2D model was able to capture the fundamental behavior of viscoelastic tape springs during both snap-through and snap-back paths.

Place, publisher, year, edition, pages
Elsevier, 2021
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-286338 (URN)10.1016/j.compstruct.2020.113181 (DOI)000609370200008 ()2-s2.0-85096533830 (Scopus ID)
Note

QC 20201208.

QC 20210408.

Available from: 2020-11-25 Created: 2020-11-25 Last updated: 2022-06-25Bibliographically approved
Mallol, P., Mao, H. & Tibert, G. (2018). Experiments and simulations of the deployment of a bistable composite boom. Journal of Spacecraft and Rockets, 55(2), 292-302
Open this publication in new window or tab >>Experiments and simulations of the deployment of a bistable composite boom
2018 (English)In: Journal of Spacecraft and Rockets, ISSN 0022-4650, E-ISSN 1533-6794, Vol. 55, no 2, p. 292-302Article in journal (Refereed) Published
Abstract [en]

The rapidly growing use of small satellites for space missions requires deployable systems to be highly storable yet large and with adequate mechanical properties when deployed. This paper focuses on the modeling and simulation of a meter-class passively deployable boom, based on the self-contained linear meter-class deployable boom, exploiting the bistable nature of composite shells. Experimental tests were performed on a boom prototype suspended in a gravity offloading system. The strain energy level, deployment time, and spacecraft displacements calculated from the finite element method agree well with analytical analyses, confirming the theoretical accuracy of the finite element method. Because friction and strain energy relaxation were not included in the model, the finite element simulations predicted deployment times up to five times shorter than those of the gravity offloaded boom experiments. The quick deployment and violent end-of-deployment shock created boom deployment dynamics that were not seen in the experiments. The observed differences between the finite element model and the tests were mainly due to inaccurate material and friction models.

Place, publisher, year, edition, pages
American Institute of Aeronautics and Astronautics Inc., 2018
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-225495 (URN)10.2514/1.A33906 (DOI)000428346600004 ()2-s2.0-85044458459 (Scopus ID)
Note

QC 20180406

Available from: 2018-04-06 Created: 2018-04-06 Last updated: 2022-12-12Bibliographically approved
Yuan, Y., Tibert, G. & Ivchenko, N. (2017). Attitude reconstruction of suborbital small spacecrafts using a global optimization method. Acta Astronautica
Open this publication in new window or tab >>Attitude reconstruction of suborbital small spacecrafts using a global optimization method
2017 (English)In: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030Article in journal (Other academic) Submitted
Abstract [en]

Attitude motion of suborbital payloads is closely related to the quality of scientic measurements. In this paper, attitude reconstruction of suborbital payloads in terms of yaw-pitch-roll Euler angle is studied, according to measurements of magnetic fields from a magnetometer and angular velocities from a gyro sensor. To avoid complex dynamical modelling, the kinematic equations were used. The Euler angles were established by using an global optimization method. Moreover, the Euler angles were estimated by employing Unscented Kalman Filter (UKF) technique. The comparison of the optimized results to the ones from the UKF shows that the global optimization method provides higher accuracy than the UKF.

National Category
Aerospace Engineering
Identifiers
urn:nbn:se:kth:diva-206849 (URN)
Note

QC 20170509

Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2024-03-15Bibliographically approved
Mao, H., Ganga, P. L., Ghiozzi, M., Ivchenko, N. & Tibert, G. (2017). Deployment of Bistable Self-Deployable Tape Spring Booms Using a Gravity Offloading System. Journal of Aerospace Engineering, 30(4)
Open this publication in new window or tab >>Deployment of Bistable Self-Deployable Tape Spring Booms Using a Gravity Offloading System
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2017 (English)In: Journal of Aerospace Engineering, ISSN 0893-1321, E-ISSN 1943-5525, Vol. 30, no 4Article in journal (Refereed) Published
Abstract [en]

Bistable tape springs are suitable as deployable structures thanks to their high packaging ratio, self-deployment ability, low cost, light weight, and stiffness. A deployable booms assembly composed of four 1-m long bistable glass fiber tape springs was designed for the electromagnetically clean 3U CubeSat Small Explorer for Advanced Missions (SEAM). The aim of the present study was to investigate the deployment dynamics and reliability of the SEAM boom design after long-term stowage using onground experiments and simulations. A gravity offloading system (GOLS) was built and used for the onground deployment experiments. Two booms assemblies were produced and tested: a prototype and an engineering qualification model (EQM). The prototype assembly was deployed in a GOLS with small height, whereas the EQM was deployed in a GOLS with tall height to minimize the effects of the GOLS. A simple analytical model was developed to predict the deployment dynamics and to assess the effects of the GOLS and the combined effects of friction, viscoelastic relaxation, and other factors that act to decrease the deployment force. Experiments and simulations of the deployment dynamics indicate significant viscoelastic energy relaxation phenomena, which depend on the coiled radius and stowage time. In combination with friction effects, these viscoelastic effects decreased the deployment speed and the end-of-deployment shock vibrations. 

Place, publisher, year, edition, pages
Journal of Aerospace Engineering: , 2017
Keywords
Bi-stable tape spring, CubeSat Boom, Viscoelasticity, Gravity offloading system
National Category
Aerospace Engineering
Research subject
Aerospace Engineering
Identifiers
urn:nbn:se:kth:diva-206545 (URN)10.1061/(ASCE)AS.1943-5525.0000709 (DOI)000399893000007 ()2-s2.0-85018756963 (Scopus ID)
Projects
SEAM
Funder
EU, FP7, Seventh Framework Programme, 607197
Note

QC 20170508

Available from: 2017-05-05 Created: 2017-05-05 Last updated: 2024-03-15Bibliographically approved
Mao, H., Shipsha, A. & Tibert, G. (2017). Design and Analysis of Laminates for Self-Deployment of Viscoelastic Bistable Tape Springs after Long-Term Stowage. Journal of applied mechanics, 84(7), Article ID 071004.
Open this publication in new window or tab >>Design and Analysis of Laminates for Self-Deployment of Viscoelastic Bistable Tape Springs after Long-Term Stowage
2017 (English)In: Journal of applied mechanics, ISSN 0021-8936, E-ISSN 1528-9036, Vol. 84, no 7, article id 071004Article in journal (Refereed) Published
Abstract [en]

Bistable tape springs are ultrathin fiber-reinforced polymer composites, which could self-deploy through releasing stored strain energy. Strain energy relaxation is observed after long-term stowage of bistable tape springs due to viscoelastic effects and the tape springs might lose their self-deployment abilities. In order to mitigate the viscoelastic effects and thus ensure self-deployment, different tape springs were designed, manufactured, and tested. Deployment experiments show that a four-layer, [â '45/0/90/45], plain weave glass fiber tape spring has a high capability to mitigate the strain energy relaxation effects to ensure self-deployment after long-term stowage in a coiled configuration. The two inner layers increase the deployment force and the outer layers are used to generate the bistability. The presented four-layer tape spring can self-deploy after more than six months of stowage at room temperature. A numerical model was used to assess the long-term stowage effects on the deployment capability of bistable tape springs. The experiments and modeling results show that the viscoelastic strain energy relaxation starts after only a few minutes after coiling. The relaxation shear stiffness decreases as the shear strain increases and is further reduced by strain energy relaxation when a constant shear strain is applied. The numerical model and experiments could be applied in design to predict the deployment force of other types of tape springs with viscoelastic and friction effects included.

Place, publisher, year, edition, pages
ASME Press, 2017
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-209528 (URN)10.1115/1.4036672 (DOI)000404714700004 ()2-s2.0-85019723210 (Scopus ID)
Note

QC 20170620

Available from: 2017-06-20 Created: 2017-06-20 Last updated: 2024-03-18Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6802-8331

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