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- Swarén, Mikael, et al.
(författare)
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Testing method for objective evaluation of cross-country ski poles
- 2013
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Ingår i: Sports Engineering. - : Springer Science and Business Media LLC. - 1369-7072 .- 1460-2687. ; 16:4, s. 255-264
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to develop an objective classification method for cross-country ski poles. A test device was designed to expose different pole models to maximal loading and impact tests. A load cell measured the axial forces in the pole shafts, and a laser distance meter measured shaft deflection when a load was applied via the wrist strap. In the loading tests, each shaft reached a plateau where no more force could be transferred. This maximal force transfer (MFT) value was a characteristic measure for flexural rigidity and thereby also strength. The developed test method enables a loading that is more similar to real-life skiing than a standard three-point bending test. Results show that the introduction of shaft indices for buckling strength is beneficial for comparison purposes. The MFT is a relevant parameter used in the characterization of poles.
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| 4. |
- Ahmed, Samih, et al.
(författare)
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Post-Tensioned Stress Ribbon Systems in Long Span Roofs
- 2019
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Ingår i: 20th Congress of IABSE, New York City 2019. - : International Association for Bridge and Structural Engineering. - 9783857481659 ; , s. 534-540
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Konferensbidrag (refereegranskat)abstract
- Cable systems have numerous advantages, such as: large column-free areas, and reduced materials consumption, which reduces the load and the cost. Nevertheless, they are rarely used in long span roofs due to large deflections, and the insufficient space for end supports, or/and back-stayed cables. This work suggests the use of post-tension stress ribbon system in long span roofs in order to reduce the pull-out forces, deflections and concrete stresses compared to a conventional cable system. A comparison is carried out through meticulous and accurate finite element simulations, using SAP2000, implemented for the new +200m roof of Västerås Travel Center (Sweden), which will become one of the longest cable suspended roofs in the world, if not the longest. Results confirm the suitability and superiority of stress ribbon systems as it reduces concrete stresses, deflections, pull-out forces and vertical reactions. These reductions are found highly correlated to the applied prestressing forces.
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- Davies Forsman, Lina, et al.
(författare)
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Fatal bupivacaine overdose through intrathecally positioned epidural catheter
- 2013
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Ingår i: Scandinavian Journal of Forensic Science. - : Walter de Gruyter. - 1503-9552. ; 19:1, s. 10-12
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Tidskriftsartikel (refereegranskat)abstract
- We describe a fatality due to an intrathecally positioned epidural catheter and an infusion rate of bupivacaine set 10 times higher than planned. The undetected misplacement, despite safety routines, is discussed along with the toxicological findings and new information on the intrathecal distribution of bupivacaine. From a clinical point of view, the human factor, in combination with an indistinct decimal point on the pump, was considered as the reason for the unfortunate overdose. In continuous epidural infusion of local anesthetics, the importance of guidelines and informed staff in managing complications of epidural lumbar infusion as well as careful monitoring of the vital functions is essential. Guidelines are also vital during the procedure of insertion of epidural catheters. When using combined spinal and epidural anaesthesia, we believe that an epidural catheter should be inserted, and its position tested, prior to spinal anesthesia. The case also illustrates the need of innovative investigation techniques to confirm the suspicion of unusual manifestations of inadvertent drug effects. Segmental analysis, together with analyses in a control case, enabled us to elucidate the high and varying tissue concentrations in the central nervous system.
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- Dijkstra, Erik J.
(författare)
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Constrained Optimization for Prediction of Posture
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ability to stand still in one place is important in a variety of activities of daily living. For persons with motion disorders, orthopaedic treatment, which changes geometric or biomechanical properties, can improve the individual'sposture and walking ability. Decisions on such treatment require insight in how posture and walking ability are aected, however, despite expectations based on experience, it is never a-priori known how a patient will react to a treatment. As this is very challenging to observe by the naked eye, engineering tools are increasingly employed to support clinical diagnostics and treatment planning. The development of predictive simulations allows for the evaluation of the eect of changed biomechanical parameters on the human biological system behavior and could become a valuable tool in future clinical decision making. In the first paper, we evaluated the use of the Zero Moment Point as a computationally inexpensive tool to obtain the ground reaction forces (GRFs) for normal human gait. The method was applied on ten healthy subjects walking in a motion analysis laboratory and predicted GRFs are evaluated against the simultaneously measured force plate data. Apart from the antero-posterior forces, GRFs are well-predicted and errors fall within the error ranges from other published methods. The computationally inexpensive method evaluated in this study can reasonably well predict the GRFs for normal human gait without using prior knowledge of common gait kinetics. The second manuscript addresses the complications in the creation and analysis of a posture prediction framework. The fmincon optimization function in MATLAB was used in conjunction with a musculoskeletal model in OpenSim. One clear local minimum was found in the form of a symmetric standing posture but perturbation analyses revealed the presence of many other postural congurations, each representing its own unique local minimum in the feasible parameter space. For human postural stance, this can translate to there being many different ways of standing without actually noticing a difference in the efforts required for these poses.
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- Eriksson, Anders, et al.
(författare)
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Supporting Organizational Readiness when Implementing Robot in a Collaborative Environment
- 2021
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Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728129891
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Konferensbidrag (refereegranskat)abstract
- Industry 4.0 brings several technologies that might be useful for manufacturers to become more competitive. One of these technologies is robots in collaborative environments (RCE), which operate fenceless together with the operators. The interest of these robots in the manufacturing sector has been getting more attention recently. Nevertheless, manufacturers should determine their organization's readiness for implementing RCE successfully. Therefore, this paper presents results from a case study conducted at a manufacturing company in Sweden. The case study approach allowed for insights into how manufacturers can approach RCE organizational readiness. The investigated case company was in the process of acquiring a robot in a collaborative environment. The resulting list of critical factors contains aspects concerning four areas to support organizational readiness for RCE, namely, communication, knowledge, organizational, and resistance. By addressing the critical factors presented in the list, manufacturers can identify critical organizational readiness aspects when implementing RCE.
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| 8. |
- Hansson, Linnea J., et al.
(författare)
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Autoplant—Autonomous Site Preparation and Tree Planting for a Sustainable Bioeconomy
- 2024
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Ingår i: Forests. - : MDPI. - 1999-4907. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable forestry requires efficient regeneration methods to ensure that new forests are established quickly. In Sweden, 99% of the planting is manual, but finding labor for this arduous work is difficult. An autonomous scarifying and planting machine with high precision, low environmental impact, and a good work environment would meet the needs of the forest industry. For two years, a collaborative group of researchers, manufacturers, and users (forest companies) has worked together on developing and testing a new concept for autonomous forest regeneration (Autoplant). The concept comprises several subsystems, i.e., regeneration and route planning, autonomous driving (path planning), new technology for forest regeneration with minimal environmental impact, automatic plant management, crane motion planning, detection of planting spots, and follow-up. The subsystems were tested separately and integrated together during a field test at a clearcut. The concept shows great potential, especially from an environmental perspective, with significantly reduced soil disturbances, from approximately 50% (the area proportion of the area disturbed by disc trenching) to less than 3%. The Autoplant project highlights the challenges and opportunities related to future development, e.g., the relation between machine cost and operating speed, sensor robustness in response to vibrations and weather, and precision in detecting the size and type of obstacles during autonomous driving and planting.
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| 9. |
- Jonas, Örtegren, et al.
(författare)
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Cone motion viscosity and optical second harmonic generation of ferroelectric liquid crystalline dendrimers
- 2001
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Ingår i: Liquid crystals (Print). - : Informa UK Limited. - 0267-8292 .- 1366-5855. ; 28:6, s. 861-868
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Tidskriftsartikel (refereegranskat)abstract
- We report second harmonic generation in a ferroelectric liquid crystalline trimer and ferroelectric liquid crystalline dendrimers of first, second and third generation. Thin cells were filled with the compounds by capillary forces at elevated temperature, and cooled from the surface stabilized ferroelectric state to below the glass transition temperature, while kept in an electric field. The cone motion viscosity and the threshold electric field for unwinding of the helix axis of the chiral tilted smectic mesophases were studied separately at elevated temperature, and these data were used to optimize the preparation of the films. The measured response time was between 0.3 and 3 ms, which corresponds to a cone motion viscosity between 0.5 and 50 Pa s. Second harmonic generation was studied both at elevated temperature with an electric field and at room temperature with and without electric field. The first generation dendrimer exhibited a strong increase in the second order non-linear optical response with time at room temperature. The d(23)-coefficient of this dendrimer was approximately four times larger than for the other macromolecules and was 0.045 pm V-1. The relatively large d-coefficient of the first generation dendrimer is ascribed to crystallization, which improved the orientation of the molecular dipoles.
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| 10. |
- Jones, Geraint H., et al.
(författare)
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The Comet Interceptor Mission
- 2024
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Ingår i: Space Science Reviews. - : Springer Nature. - 0038-6308 .- 1572-9672. ; 220:1
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Tidskriftsartikel (refereegranskat)abstract
- Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum Δ V capability of 600 ms − 1 . Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule.
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