| 1. |
- Bäckström, Erik, 1983-, et al.
(författare)
-
Storing keV negative ions for an hour : The lifetime of the metastable 2P1/2 level in 32S−
- 2015
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 114:14
-
Tidskriftsartikel (refereegranskat)abstract
- We use a novel electrostatic ion storage ring to measure the radiative lifetime of the upper level in the 3p 5 P 2 o 1/2 →3p 5 P 2 o 3/2 spontaneous radiative decay in S − 32 to be 503±54 sec . This is by orders of magnitude the longest lifetime ever measured in a negatively charged ion. Cryogenic cooling of the storage ring gives a residual-gas pressure of a few times 10 −14 mbar at 13 K and storage of 10 keV sulfur anions for more than an hour. Our experimental results differ by 1.3σ from the only available theoretical prediction.
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| 2. |
- Gatchell, Michael, et al.
(författare)
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Commissioning of the DESIREE storage rings - a new facility for cold ion-ion collisions
- 2014
-
Ingår i: XXVIII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2013). - : Institute of Physics (IOP). ; 488:1
-
Konferensbidrag (refereegranskat)abstract
- We report on the ongoing commissioning of the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. Beams of atomic carbon anions (C-) and smaller carbon anion molecules (C-2(-), C-3(-), C-4(-) etc.) have been produced in a sputter ion source, accelerated to 10 keV or 20 keV, and stored successfully in the two electrostatic rings. The rings are enclosed in a common vacuum chamber cooled to below 13 Kelvin. The DESIREE facility allows for studies of internally relaxed single isolated atomic, molecular and cluster ions and for collision experiments between cat-and anions down to very low center-of-mass collision energies (meV scale). The total thermal load of the vacuum chamber at this temperature is measured to be 32 W. The decay rates of stored ion beams have two components: a non-exponential component caused by the space charge of the beam itself which dominates at early times and an exponential term from the neutralization of the beam in collisions with residual gas at later times. The residual gas limited storage lifetime of carbon anions in the symmetric ring is over seven minutes while the 1/e lifetime in the asymmetric ring is measured to be about 30 seconds. Although we aim to improve the storage in the second ring, the number of stored ions are now sufficient for many merged beams experiments with positive and negative ions requiring milliseconds to seconds ion storage.
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| 3. |
- Gatchell, Michael, et al.
(författare)
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First results from the Double ElectroStatic Ion-Ring ExpEriment, DESIREE
- 2014
-
Ingår i: XXVIII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2013). - : Institute of Physics (IOP). ; 488
-
Konferensbidrag (refereegranskat)abstract
- We have stored the first beams in one of the rings of the double electrostatic ion-storage ring, DESIREE at cryogenic and at room temperature conditions. At cryogenic operations the following parameters are found. Temperature; T= 13K, pressure; p <10(-13) mbar, initial number of stored ions; N > 10(7) and storage lifetime of a C-2(-) beam; tau = 450 S.
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| 4. |
- Hartman, Henrik, et al.
(författare)
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First storage of ion beams in the Double Electrostatic Ion-Ring Experiment : DESIREE
- 2013
-
Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 84:5
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (Cn-, n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2- molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s +/- 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10-14 mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.
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| 5. |
- Thomas, Richard D., et al.
(författare)
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DESIREE : Physics with cold stored ion beams
- 2015
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Ingår i: DR2013. - : EDP Sciences. ; 84, s. 01004-01004
-
Konferensbidrag (refereegranskat)abstract
- Here we will briefly describe the commissioning of the Double ElectroStatic Ion Ring ExpEriment (DESIREE) facility at Stockholm University, Sweden. This device uses purely electrostatic focussing and deflection elements and allows ion beams of opposite charge to be confined under extreme high vacuum and cryogenic conditions in separate rings and then merged over a common straight section. This apparatus allows for studies of interactions between cations and anions at very low and well-defined centre-of-mass energies (down to a few meV) and at very low internal temperatures (down to a few K).
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| 6. |
- Thomas, Richard D., et al.
(författare)
-
The double electrostatic ion ring experiment : A unique cryogenic electrostatic storage ring for merged ion-beams studies
- 2011
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 82:6, s. 065112-
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the design of a novel type of storage device currently under construction at Stockholm University, Sweden, using purely electrostatic focussing and deflection elements, in which ion beams of opposite charges are confined under extreme high vacuum cryogenic conditions in separate rings and merged over a common straight section. The construction of this double electrostatic ion ring experiment uniquely allows for studies of interactions between cations and anions at low and well-defined internal temperatures and centre-of-mass collision energies down to about 10 K and 10 meV, respectively. Position sensitive multi-hit detector systems have been extensively tested and proven to work in cryogenic environments and these will be used to measure correlations between reaction products in, for example, electron-transfer processes. The technical advantages of using purely electrostatic ion storage devices over magnetic ones are many, but the most relevant are: electrostatic elements which are more compact and easier to construct; remanent fields, hysteresis, and eddy-currents, which are of concern in magnetic devices, are no longer relevant; and electrical fields required to control the orbit of the ions are not only much easier to create and control than the corresponding magnetic fields, they also set no upper mass limit on the ions that can be stored. These technical differences are a boon to new areas of fundamental experimental research, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology. For examples, studies of interactions with internally cold molecular ions will be particular useful for applications in astrophysics, while studies of solvated ionic clusters will be of relevance to aeronomy and biology.
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| 7. |
- Ainegren, Mats, 1963-, et al.
(författare)
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A Study of Skin-Close Heat and Moisture with Different Types of Backpacks in Cycling
- 2020
-
Ingår i: The 13th Conference of the International Sports Engineering Association. - Basel Switzerland : MDPI.
-
Konferensbidrag (refereegranskat)abstract
- The aim of this project was to evaluate effects of backpacks with different design intended for use during cycling on skin-close temperature and relative humidity, oxygen uptake, heart rate and aerodynamic drag. Seven subjects took part in the study cycling on a mountain bike mounted on a “smart trainer” placed on a force plate in a wind tunnel. Three series of experiments were carried out: without backpack, with conventional backpack and with a backpack having innovative rear panel design. As hypothesized, the results showed that an innovatively designed backpack with the ducts deflecting part of the airflow towards some areas of the user’s back provided lower temperature and relative humidity for the microclimate compared to a conventional backpack without airflow channels. Further, reference tests without any backpack resulted in the lowest temperature and humidity. However, no differences were found between the three tests for oxygen uptake, heart rate and aerodynamic drag.
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| 8. |
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| 9. |
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| 10. |
- Andreasson, Jakob, 1975, et al.
(författare)
-
Franck-Condon higher order lattice excitations in the LaFe(1-x)Cr(x)O3 (x=0, 0.1, 0.5, 0.9, 1.0) perovskites due to Fe-Cr charge transfer effects
- 2007
-
Ingår i: Physical Review B. ; 75, s. 104302-
-
Tidskriftsartikel (refereegranskat)abstract
- First and higher order lattice excitiations in the B-site disordered perovskites LaFe(1-x)Cr(x)O3 (x = 0, 0.1, 0.5, 0.9, 1) and La(0.835)Sr(0.165)Fe(0.5)Cr(0.5)O(3-d) are investigated using temperature dependent and polarised inelastic light scattering [lambda = 515 nm (2.41 eV) and 676 nm (1.83 eV)] on oriented crystallites.A peak at approximately 2.4 eV in the imaginary part of the dielectric function of LaFe(0.5)Cr(0.5)O3 is assigned to a charge transfer from Fe 3+ (d5) to Cr 3+ (d3) ions and coupled the appearance of an intense Ag-like mode at approximately 700 cm-1 in the Raman data. This excitation is identified as a symmetric oxygen breathing mode activated by the Fe-Cr charge transfer through an orbital coupling mechanism. Higher order scattering (up to 7th order) of the intrinsic Raman active symmetric breathing mode is also explained by an orbital mediated, electron-phonon coupling, similar to the Franck-Condon effect observed in the Jahn-Teller active perovskite structured manganite LaMnO3. These results show that the Franck-Condon mechanism is a more common mechanism for resonant higher order scattering in solids than previously believed and propose the LaFe(1-x)Cr(x)O(3) system as a model system for electron-phonon coupling and higher order Raman scattering in solids.
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| 11. |
- Andreasson, Jakob, et al.
(författare)
-
Franck-Condon higher order lattice excitations in the LaFe1-xCrxO3 (x=0, 0.1, 0.5, 0.9, 1.0) perovskites due to Fe-Cr charge transfer effects
- 2007
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75
-
Tidskriftsartikel (refereegranskat)abstract
- First and higher order lattice excitations in the B-site disordered perovskites LaFe1-xCrxO3 (x=0, 0.1, 0.5, 0.9, and 1) and La0.835Sr0.165Fe0.5Cr0.5O3-delta are investigated using temperature dependent and polarized inelastic light scattering [lambda=515 nm (2.41 eV) and 676 nm (1.83 eV)] on oriented crystallites. A peak at approximately 2.4 eV in the imaginary part of the dielectric function of LaFe0.5Cr0.5O3 is assigned to a charge transfer from Fe3+ (d(5)) to Cr3+ (d(3)) ions, coupled with the appearance of an intense A(g)-like mode at approximately 700 cm(-1) in the Raman data. This excitation is identified as a symmetric oxygen breathing mode activated by the Fe-Cr charge transfer through an orbital coupling mechanism. Higher order scattering (up to seventh order) of the intrinsic Raman active symmetric breathing mode is also explained by an orbital-mediated electron-phonon coupling, similar to the Franck-Condon effect observed in the Jahn-Teller active-perovskite-structured manganite LaMaO(3). These results show that the Franck-Condon mechanism is a more common mechanism for resonant higher order scattering in solids than previously believed and propose the LaFe1-xCrxO3 system as a model system for electron-phonon coupling and higher order Raman scattering in solids.
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| 12. |
- Botero, Carlos Alberto, et al.
(författare)
-
Microstructural and mechanical evaluation of a cr-mo-v cold-work tool steel produced via electron beam melting (Ebm)
- 2021
-
Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 14:11
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a highly alloyed cold work tool steel, Uddeholm Vanadis 4 Extra, was manufactured via the electron beam melting (EBM) technique. The corresponding material microstructure and carbide precipitation behavior as well as the microstructural changes after heat treatment were characterized, and key mechanical properties were investigated. In the as-built condition, the mi-crostructure consists of a discontinuous network of very fine primary Mo-and V-rich carbides dispersed in an auto-tempered martensite matrix together with ≈15% of retained austenite. Adjusted heat treatment procedures allowed optimizing the microstructure by the elimination of Mo-rich carbides and the precipitation of fine and different sized V-rich carbides, along with a decrease in the retained austenite content below 2%. Hardness response, compressive strength, and abrasive wear properties of the EBM-manufactured material are similar or superior to its as-HIP forged counterparts manufactured using traditional powder metallurgy route. In the material as built by EBM, an impact toughness of 16–17 J was achieved. Hot isostatic pressing (HIP) was applied in order to further increase ductility and to investigate its impact upon the microstructure and properties of the material. After HIPing with optimized protocols, the ductility increased over 20 J.
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| 13. |
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| 14. |
- Botero Vega, Carlos Alberto, et al.
(författare)
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Additive Manufacturing of a Cold-Work Tool Steel using Electron Beam Melting
- 2020
-
Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 19:5, s. 1-6
-
Tidskriftsartikel (refereegranskat)abstract
- Metal additive manufacturing (AM) is on its way to industrialization. One of the most promising techniques within this field, electron beam melting (EBM), is nowadays used mostly for the fabrication of high‐performance Ti‐based alloy components for the aerospace and medical industry. Among the industrial applications envisioned for the future of EBM, the fabrication of high carbon steels for the tooling industry is of great interest. In this context, the process windows for dense and crack‐free specimens for a highly alloyed (Cr–Mo–V) cold‐work steel powder are presented in this article. High‐solidification rates during EBM processing lead to very fine and homogeneous microstructures. The influence of process parameters on the resulting microstructure and the chemical composition is investigated. In addition, preliminary results show very promising mechanical properties regarding the as‐built and heat‐treated microstructure of the obtained material.
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| 15. |
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| 16. |
- Bäckström, Anders, 1944-, et al.
(författare)
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Thorleif Pettersson in memoriam
- 2010
-
Annan publikation (populärvet., debatt m.m.)abstract
- Minnesord över professor Thorleif Pettersson den 21 maj 2010 i Upsala Nya Tidning.
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| 17. |
- Bäckström, Mikael, et al.
(författare)
-
A New Wind Tunnel Facility Dedicated to Sports Technology Research and Development
- 2016
-
Ingår i: Procedia Engineering. - : Elsevier. ; , s. 62-67
-
Konferensbidrag (refereegranskat)abstract
- It is desirable to test sportswear and sports equipment at exactly the same conditions experienced during use. Although outdoor tests are in many cases the most adequate, they are at the same time quite complex, demand special measurement technology and wearable equipment. Results of such tests are often hard to interpret due to large variations because of rapidly varying ambient conditions and individual specifics of human objects, among other factors, which are hard or impossible to control. One common alternative is provided through indoor tests made in a stable, controlled environment. Controlling such parameters as temperature, wind speed and direction, air humidity with indoor facilities intended to replicate ambient conditions, and designed to house large objects, is a complex undertaking. Furthermore, replicating seasonal conditions complicates matters even more. A significant amount of research and development related to the operation of sports and other related equipment at high speeds and windy conditions has been carried out in wind tunnels with different degrees of climatic realism. However, the majority of such facilities are designed and constructed for the automotive industry, the aerospace industry and for marine research. A new wind tunnel facility, opened in March 2015 at the Sports Tech Research Centre at Mid Sweden University, is currently among the very few facilities in the world designed under the direct control of sports technology specialists and dedicated primarily to research and development within sports, outdoor clothing and footwear as well as equipment development and testing. The main goal when constructing this dedicated facility has been to successfully replicate ambient conditions for training and equipment testing in environments with controlled wind speed, temperature (+4 to +35°C) and precipitation (from fine mist to heavy downfall). The wind tunnel facility houses the largest moving belt in Sweden (5 m long and 2.7 m wide) which can be adjusted for leveled, uphill and downhill motion. The moving belt is placed in a 10 m2 test section in which the wind speed can be adjusted to match belt speed or independently up to 55 km/h (without narrowing the test section). A fog and rain system, mounted in the test section, can generate rainy conditions varying from fine mist to heavy monsoon. It is also possible to open the facility in order to allow experiments to be performed in wide range of outdoor, ambient conditions. This paper presents the basic parameters of the new wind tunnel facility. As this facility is open for wider international cooperation, we also report the general directions of current research and the future work planned to be carried out at this facility.
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| 18. |
- Bäckström, Mikael, et al.
(författare)
-
A step towards integrated supervisory control of complex machining processes
- 1998
-
Ingår i: Changing the ways we work : shaping the ICT-solutions for the next century : proceedings of the Conference on Integration in Manufacturing, Göteborg, Sweden, 6-8 October 1998. - Amsterdam : IOS press. - 9051994265 ; , s. 817-
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Konferensbidrag (refereegranskat)
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| 19. |
- Bäckström, Mikael, et al.
(författare)
-
An approach to integrated process monitoring and quality control of advanced machining
- 1999
-
Ingår i: Life cycle approaches to production systems : management, control, and supervision; preprints; ASI '99; Advanced Summer Institute '99, ICIMS-NOE; September 22 - 24, 1999, Leuven, Belgium. - Leuven, Belgien. ; , s. 150-
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Konferensbidrag (refereegranskat)
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| 20. |
- Bäckström, Mikael, 1963-, et al.
(författare)
-
Critical Factors Influencing Loss of Time after Shooting - A Case Study Performed During the 2008 IBU Biathlon World Championships
- 2009
-
Ingår i: The Impact of Technology on Sport III. - 9781921426391 ; , s. 33-37
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The final result during a biathlon race is a composition of skiing, shooting and in some cases penalty time or rounds. One of the most decisive parts of the competition is the shooting component. The shooting component itself can be subdivided into separate parts: Actions just before shooting, the shooting itself and actions after the shooting. In the case of a slow approach to the firing line partially caused by dismounting of ski poles, time loss is tactically accepted by some skiers – heart rate decreases and a mental focus can be obtained. A slow departure from the firing line and the subsequent loss of time is on the contrary absolutely not desirable. A part of the lost time after shooting is observed to be related to mounting the ski poles. Modern ski poles can be divided into three groups of strap systems: 1. Simple loop; 2. Strap with Velcro fastener; 3. Click-in (typically Leki). The paper presents a case study aimed at finding how the ski pole strapping system influences time loss after shooting. The study was performed during the IBU Biathlon World Championship 2008 in Östersund, Sweden. Time measurements were made over a defined distance allowing the athletes to approach cruising speed after the last shot in a series. The measurements for each athlete have been normalized relative his/her racing performance. The results clearly indicate time differences between strap systems. In some cases the differences could mean achieving podium place or not.
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| 21. |
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| 22. |
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| 23. |
- Bäckström, Mikael, et al.
(författare)
-
Development of a multi-tooth approach to tool condition monitoring in milling
- 1998
-
Ingår i: Insight. - 1354-2575 .- 1754-4904. ; 40:8, s. 548-552
-
Tidskriftsartikel (refereegranskat)abstract
- The need to develop reliable, adequate and cost-efficient methods for tool condition monitoring in milling has been emphasized by industry for a long time. The development of such methods has to deal with many difficulties such as complex machining conditions and a large number of available process variables. The paper presents the development of a multi-tooth approach to tool condition monitoring applied to milling where the inherent methods have been evaluated in experimental studies. Non-traditional methods such as multivariate techniques have been used to handle the large amount of process information that become accessible during machining. The developed methods are applied on different aspects of tool condition monitoring where the results obtained create opportunities for future research.
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Bäckström, Mikael, et al.
(författare)
-
Integration of real-time quality control and process monitoring
- 2000
-
Ingår i: The 33rd CIRP International Seminar on Manufacturing Systems : the manufacturing systems in its human context : a tool to extend the global welfare : 5-7 June, 2000, Stockholm, Sweden : proceedings.. - Sth. : KTH, Inst.för farkost och flyg. ; , s. 438-, s. 414-419
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Konferensbidrag (refereegranskat)
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| 28. |
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| 29. |
- Bäckström, Mikael, 1963-
(författare)
-
On Monitoring and Control of Machining Processes
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis presents several aspects related to the industrial and academic activities associated with monitoring and control of the machining process and machine tools A survey of the industrial situation identified some key factors for a successful implementation of monitoring and control techniques. Applicable, relatively simple, systems for cutting-process monitoring and adaptive control are available on the commercial market today but the degree of industrial utilisation of the technique is low because the systems are experienced as hard to operate and use, and are at the same time considered unreliable. In order to promote a higher degree of industrial utilisation more work has to be devoted raising the performance of the system solutions. An Integrated Supervisory Process Control (ISPC) concept is presented as an approach dealing with multi-purpose control requirements utilising the individual advantages of several sensors and modelling techniques. The ISPC system is supposed to operate as a conceptual integration of sensors, process models and different control modules. Two prototype systems, based on five-axis machining centres, for real-time control of the machining process are outlined. Different strategies for monitoring and control are developed, implemented and experimentally tried out, and the studies conducted demonstrate results that encourage further research work devoted to verification of the proposed control concept. The results obtained in the initial experiments utilising methods for process control and monitoring, such as double exponential smoothing technique (DES), multivariate monitoring applied to signal tracking and artificial neural networks applied to cutting torque control, reveal that the different techniques have potential to improve the performance of monitoring and control tasks, thus contributing to the creation of more sophisticated and reliable solutions in the ISPC concept.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Bäckström, Mikael, 1963-, et al.
(författare)
-
People and Skis
- 2006
-
Ingår i: Science-First Hand. - Novosibirsk : INFOLIO Publishing House. - 1810-8520. ; :3, s. 110-125
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 34. |
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| 35. |
- Bäckström, Mikael, et al.
(författare)
-
QFD as a tool to improve quality control in a complex manufacturing environment
- 2004
-
Ingår i: Asian Journal on Quality. - : Emerald. - 1598-2688. ; 5:1, s. 10-22
-
Tidskriftsartikel (refereegranskat)abstract
- The paper outlines a comprehensive three‐step approach to the development of advanced strategies for quality control of a complex machining process. The research framework is a developed concept for Integrated Supervisory Process Control. The promising results obtained demonstrate a non‐traditional approach to the deployment of quality and productivity requirements set by the system users, whereby the efficiency and systematization of the development of quality control strategies can be significantly improved.
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| 36. |
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| 37. |
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| 38. |
- Bäckström, Mikael, et al.
(författare)
-
Sports Technology Education at Mid Sweden University
- 2013
-
Ingår i: 6TH ASIA-PACIFIC CONGRESS ON SPORTS TECHNOLOGY (APCST). - : Elsevier. ; , s. 214-219
-
Konferensbidrag (refereegranskat)abstract
- In present paper we would like to share some experiences of building new education in Sports Technology at MidSweden University and the results of 10 years of successfully running it in Östersund. The Sports Technologyeducation at Mid Sweden University started at Campus Östersund in 2003 as a part of the curriculum of theEngineering Department. This specialization was initially at the three-year Bachelor level, and later it was extendedto an additional two-year Master level. Aiming at the quality of Sports Technology education, three keystones areunderlying its process, representing the solid knowledge base, capacity to be flexible in problem solving and the usean innovative approaches. The Department unites researches with a background in both natural sciences andengineering disciplines, having a wide experience of working with and within the industry, equally active in researchand teaching. The unique constellation of the profiles forming the Department include not only the SportsTech®group, being “the backbone”, but also the Ecology and Eco-technology, and Quality Technology groups bringing theexcellence and extra competence needed to assure the quality of the Sports Technology education. We were the firsthigher education institution in Sweden to give this kind of education program and now some other SwedishUniversities have followed us. Our success can be measured by a number of graduates taking good jobs in theindustry. We also enjoy a steady flow of new students coming from all parts of Sweden, and Sports Technologyeducation stays among the most desirable ones in the country.
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| 39. |
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| 40. |
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| 41. |
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| 42. |
- Bäckström, Åsa, 1966-, et al.
(författare)
-
Routes and roots to knowing in Shaun White’s snowboarding road trip : A mycorrhizaic approach to multisensory emplaced learning in exergames
- 2019
-
Ingår i: Scandinavian Sport Studies Forum. - Malmö : Department of Sport Sciences, Malmö University. - 2000-088X. ; 10, s. 251-278
-
Tidskriftsartikel (refereegranskat)abstract
- This article explores learning during game-play of a snowboarding video game intrigued by questions raised in the wake of the increasing mediatisation and digitisation of learning. Correspondingly, we answer to calls for more suitable metaphors for learning to cater for the entangled learning processes that changes related to the increase of digital media may infer. Using a short term sensory ethnography approach, we elaborate on the idea of multisensory emplaced learning and propose an organic metaphor – mycorrhiza – to both methodology and learning. Mycorrhiza refers to a symbiotic relationship between fungi and roots of plants in its environment where fungi are the visible effects of the mycorrhiza. The metaphor provides a way to start to unpack sensory, visual and embodied aspects of learning in the complexities of the digital age. By elaborating on the mycorrhizaic concepts fungus, soil, growth, mycelia and symbiosis we show three interrelated ways of moving through this game: (i) a social and cultural route, (ii) a competitive route, and (iii) an experiential route. With help of the metaphor we discern the symbiotic relations between what appeared in our empirical material as visual and other human and non-human aspects of emplacement.
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| 43. |
- Cai, D. Q., et al.
(författare)
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A study of control chart for adjusted processes
- 1999
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Ingår i: The 26th International Conference on Computers & Industrial Engineering (the 26th C & IE) : December 15-17, 1999, Melbourne, Australia. ; , s. 443-447, s. 443-447
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Konferensbidrag (refereegranskat)
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| 44. |
- Carlsson, Peter, et al.
(författare)
-
Cross-Country Ski
- 2015
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Ingår i: The Engineering Approach to Winter Sports. - New York, NY : Springer. - 9781493930197 ; , s. 107-152
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Cross-country skiing, biathlon and ski orienteering are competitive sports with practitioners who are mostly from countries in the northern hemisphere. The competition season is during the time when the ground is covered with snow, which roughly extends from mid-November to late March. During the rest time of the year, which is a long preparatory period of training for the skiers before the competition season, the skiers use roller skis for dryland training with the aim of imitating skiing on snow. Furthermore, over the last few decades, fairly specific indoor testing methods for cross-country skiers have become possible due to the development of treadmills that allow roller skiing using classical and freestyle techniques.
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| 45. |
- Cronskär, Marie, et al.
(författare)
-
Application of electron beam melting to titanium hip stem Implants
- 2008
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Konferensbidrag (refereegranskat)abstract
- The Free Form Fabrication Process (FFF) is nowadays an accepted technology widely used for prototyping and manufacturing. However, it is still in an expansive phase and new applications like direct manufacturing of implants are evolving continuously. Present work describes the possibilities provided by the electron beam melting (EBM) method for orthopedics; in particular hip stem implant manufacturing. The conventional machining used for individually adapted prostheses typically involves advanced milling with the drawback of removing up to 80% of the material. This paper addresses the economic feasibility of using an additive approach for the manufacturing of typical orthopedic implants. The studied implants were manufactured from biocompatible Ti-6Al-4V alloy using both EBM and conventional CNC technologies and compared according to material consumption, manufacturing time and cost.
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| 46. |
- Cronskär, Marie, et al.
(författare)
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Implementation of digital design and solid free-form fabrication for customization of implants in trauma orthopaedics
- 2012
-
Ingår i: Journal of medical and biological engineering. - : Taiwanese Society of Biomedical Engineering. - 1609-0985. ; 32:2, s. 91-96
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Tidskriftsartikel (refereegranskat)abstract
- Bone plates for the fixation of complex fractures in proximity to joints often have to be reshaped to follow the bone contour. Good adhesion of the screws in areas where the bone is osteoporotic is also a challenge. One possible solution to these issues is to tailor-make plates by creating a digital three-dimensional model of the fracture from a computed tomography (CT) scan, digitally reducing the fracture, designing a plate, and finally manufacturing it directly from the digital model with solid free-form fabrication (SFF) technology. This study designs a custom plate for a distal tibia fracture, and investigates and refines the procedure from the CT scan to the final implant, with the aim of making it usable in trauma orthopaedics. The bone plate is manufactured using electron beam melting (EBM) technology. The challenges of bone plate design using digitalization and SFF are discussed. The virtual models created by the engineer while digitally reducing the fracture and modeling the plate are valuable for the physician while planning the surgery. A combination of surgery planning and digital plate design improves the surgeon's preparations and ensures correspondence between the plan and the designed implant. The proposed procedure, with the approximate required time in brackets, includes the separation of bone in the DICOM file (60 min), the reduction of fracture (5-30 min), revision (30 min), modelling of the plate (30-120 min), confirmation (30 min), manufacturing with SFF (10 h), post-processing (60 min), and finally cleaning and sterilization (90 min). The whole procedure requires about three working days.
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| 47. |
- Cronskär, Marie, et al.
(författare)
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Modeling of fractured clavicles and reconstruction plates using CAD, finite element analysis and real musculoskeletal forces input
- 2013
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Ingår i: WIT Transactions on Biomedicine and Health. - : WIT Press. - 9781845647063 ; , s. 235-243
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Konferensbidrag (refereegranskat)abstract
- This study focuses on the treatment options for clavicle fractures, more specifically the cases with a need for internal fixation: non-unions and some complex fractures. Enhancing the understanding of the loading of the bone and fixation device enables treatment options to be improved. The aim of the study was to develop a method for the realistic simulation of stresses and displacements in the bone and fixation device and to use this method to make comparisons between a conventional reconstruction plate and a customized plate, designed from patient-specific computed tomography (CT) data. In an earlier study, a finite element (FE) mesh of the clavicle geometry was created from CT data, subjected to muscle forces and other boundary conditions from a multibody musculoskeletal model and imported into the FE solver. In this study, a solid 3D model of the same clavicle geometry was created and the mesh was replaced by the solid model to make the FE-model more suitable for the comparison of different plates. An LCP Reco-Plate 3.5 straight, 6 holes (by Synthes) was compared with a customized plate which was designed to follow the anatomy of the bone. The LCP-Reco plate has tapered reconstruction segments throughout the plate to allow for the plate reshaping during surgery. The customized plate was designed without such segments and with a lower width than the LCP plate. The two different plates showed stresses and displacements of similar magnitudes. The customized plate had a more even stress distribution while the LCP plate had higher stress concentrations in the middle of the plate and on the edges of the tapered reconstruction segments. To the authors' best knowledge, this is the first FE model of a clavicle bone with plate and it may, upon further development, serve as a useful instrument for improved clavicle fixation.
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| 48. |
- Cronskär, Marie
(författare)
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On customization of orthopedic implants - from design and additive manufacturing to implementation
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral thesis is devoted to studying the possibilities of using additive manufacturing (AM) and design based on computed tomography (CT), for the production of patient-specific implants within orthopedic surgery, initially in a broad perspective and, in the second part of the thesis focusing on customized clavicle osteosynthesis plates. The main AM method used in the studies is the Electron Beam Melting (EBM) technology. Using AM, the parts are built up directly from 3D computer models, by melting or in other ways joining thin layers of material, layer by layer, to build up the part. Over the last 20 years, this fundamentally new way of manufacturing and the rapid development of software for digital 3D reconstruction of anatomical models from medical imaging, have opened up entirely new opportunities for the design and manufacturing of patient-specific implants. Based on the information in a computed tomography (CT) scan, both digital and physical models of the anatomy can be created and of implants that are customized based on the anatomical models. The main method used is a number of case studies performed, focusing on different parts of the production chain, from CT-scan to final implant, and with several aims: learning about the details of the different steps in the procedure, finding suitable applications, developing the method and trying it out. The first study was on customized hip stems, focusing on the EBM method and its special preconditions and possibilities. It was followed by a study of bone plates, designed to follow the patient-specific bone contour, in this case a tibia fracture including the whole production chain. Further, four cases of patient-specific plates for clavicle fracture fixation were performed in order to develop and evaluate the method. The plates fit towards the patient’s bone were tested in cooperation with an orthopedic surgeon at Östersund hospital. In parallel with the case studies, a method for finite element (FE) analysis of fixation plates placed on a clavicle bone was developed and used for the comparative strength analysis of different plates and plating methods. The loading on the clavicle bone in the FE model was defined on a muscle and ligament level using multibody musculoskeletal simulation for more realistic loading than in earlier similar studies. The initial studies (papers I and II) showed that the EBM method has great potential, both for the application of customized hip stems and bone plates; in certain conditions EBM manufacturing can contribute to significant cost reductions compared to conventional manufacturing methods due to material savings and savings in file preparation time. However, further work was needed in both of the application areas before implementation. The studies on the fracture fixation using patient-specific clavicle plates indicated that the method can facilitate the work for the surgeon both in the planning and in the operating room, with the potential of a smoother plate with a better fit and screw positioning tailored to the specific fracture (paper VI). However, a large clinical trial is required to investigate the clinical benefit of using patient-specific plates. The FE simulations showed similar stress distributions and displacements in the patient-specific plates and the commercial plates (papers III to VI). To summarize: the results of this thesis contribute to the area of digital design and AM in patient-specific implants with broad basis of knowledge regarding the technologies used and areas in which further work is needed for the implementation of the technology on a larger scale. Further, a method has been developed and initially evaluated for implementation in the area of clavicle fracture fixation, including an approach for comparing the strength of different clavicle plates.
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| 49. |
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| 50. |
- Cronskär, Marie, et al.
(författare)
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Patient-Specific Clavicle Reconstruction Using Digital Design and Additive Manufacturing
- 2015
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Ingår i: Journal of mechanical design (1990). - : ASME Press. - 1050-0472 .- 1528-9001. ; 137:11
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Tidskriftsartikel (refereegranskat)abstract
- There is a trend toward operative treatment for certain types of clavicle fractures and these are usually treated with plate osteosynthesis. The subcutaneous location of the clavicle makes the plate fit important, but the clavicle has a complex shape, which varies greatly between individuals and hence standard plates often have a poor fit. Using computed tomography (CT) based design, the plate contour and screw positioning can be optimized to the actual case. A method for patient-specific plating using design based on CT-data, additive manufacturing (AM), and postprocessing was initially evaluated through three case studies, and the plate fit on the reduced fracture was tested during surgery (then replaced by commercial plates). In all three cases, the plates had an adequate fit on the reduced fracture. The time span from CT scan of the fracture to final implant was two days. An approach to achieve functional design and screw-hole positioning was initiated. These initial trials of patient-specific clavicle plating using AM indicate the potential for a smoother plate with optimized screw positioning. Further, the approach facilitates the surgeon's work and operating time can be saved.
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