| 34711. |
- Linderholt, Andreas, 1968-, et al.
(författare)
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Optimizing the informativeness of test data used for computational model updating
- 2005
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Ingår i: Mechanical systems and signal processing. - : Elsevier. - 0888-3270 .- 1096-1216. ; 19:4, s. 736-750
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Tidskriftsartikel (refereegranskat)abstract
- In advance of a computational model updating or an error localisation, it can be advantageous to make a preparatory error localisation using data from a nominal analytical model. The purpose is then to select parameters for quantifying model errors and also to design effective tests for determining the best parameter setting. For successful subsequent error localisation, the test data must be informative with respect to the model parameters chosen when such data become available after test. The demand for test data informativeness puts requirements on the experiment with regard to spatial resolution of sensors, bandwidth of excitation, signal-to-noise ratios, etc.Optimising a test design is a huge task, sometimes impossible in practice, due to its combinatorial nature. The number of possible sensor/actuator placement combinations grows rapidly as the number of sensor and actuator candidates increases. For industrial sized problems, finding a sub-optimal solution may be a more realistic target. Such solutions are sought in this work.The aim of this study is to quantify data informativeness, shown to relate to the Fisher information matrix, with respect to physical parameters that are used in error localisation and model updating. Deterministic finite-element models in combination with stochastic noise models are used for assessing data informativeness, and a procedure for test design optimisation with respect to this is devised.
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| 34712. |
- Linderoth, Henrik, et al.
(författare)
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Perceived potential of BIM – the mediating role of practice.
- 2017
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Ingår i: Proceedings International Conference on Civil and Building Engineering Informatics (ICCBEI), Taiwan, April 19-21..
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Konferensbidrag (refereegranskat)abstract
- BIM is claimed to be one of the most promising developments in the industry and many researchers and practitioners seem to agree on BIM’s potential applicability in- and benefits for construction. However, what the potential, or full potential is, is a bit unclear. As well as for other Information and Communication Technologies (ICT), an objective full potential for BIM does not exist due to technology and knowledge development. But is there some alternative concept instead of potential that better capture the technologies enabling features and the interpretive dimensions? The concept of IT-affordance has been used to describe the appropriation of open ended flexible technologies and is described as: a potential for action that emerges out of the interrelationships among the technical features of a system, people’s ability and predisposition to use these features in certain ways, and the organizational context within which this takes place. The aim of the paper is to explore how the blend of technology’s features, people’s abilities and predispositions, and the organizational context influence the perceived potential for action (PPA). This will be achieved by a survey to three different groups: practitioners with and without experience of BIM-use, and last year’s bachelor students in civil engineering. It is concluded that experience of technology has a positive impact on PPA, but a blend of experiences from BIM use in practice and circumstances in practice has a strong negative moderating effect on users PPA. Among practitioners with experience of BIM, the PPA is aligned with the project logic. this is, PPA is strongly predicted by perceptions of BIM as mean for supporting decisions for cost reduction, at the same time as lack of internal competence is perceived as a constraint.
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| 34713. |
- Linderoth, Henrik, 1962-, et al.
(författare)
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What is the “Potential” of new ICT and how are Perceptions Shaped by Experience of Use and Practice? - The Case of Building Information Modelling
- 2016
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Ingår i: The 27th Australasian Conference on Information Systems. - 9781741282672
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Konferensbidrag (refereegranskat)abstract
- The emergence of new open ended ICT (Information and communication Technology). is often accompanied by optimistic predictions about the technologies inherent capabilities, or “potential”, to solve a wide array organizational related problems. In the building and construction industry, BIM – Building Information Modelling – is such an example. However, unrealistic expectations about a technology is also a determinant for failed implementations, but at the same time ICT-induced transformation of organizations and industries is a well-known phenomenon. This research in progress paper has two interlinked explorative aims. First, how can the “potential” of a technology be captured? Second, how does experience of practice and experience of technology use shape the perceived potential of a technology. The data is collected via a survey to practitioners, with and without BIM-experiences, in medium sized contractor companies, and last year’s bachelor students in civil engineering. The total number of respondents was 205. In order to achieve the first aim, it is needed to inquire how users and prospective users’ perception of a technology’s “potential” can be captured? It can be claimed that constructs used when adoption of open ended ICT is studied, implicitly or explicitly, emphasize a status quo, then a transformation of organizational processes and structures. The results show that one alternative for measuring perceived “potential” is to measure respondents’ perceptions about how useful different applications are in practice. However, this scale needs to be developed in order to become more applicable different industries. Based on the measurement of perceived “potential” the results indicate that experience of practice had a negative impact on the perceived “potential”, whereas experience of technology had a positive impact compared to respondents with experience of practice but no experience of technology. It is concluded that further research is needed on which factors these shape the perceived potential when experienced technology user also gain an increased experience of practice.
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| 34714. |
- Linderoth, Jonas, 1970, et al.
(författare)
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Should I stay or should I go? A Study of Pickup Groups in Left 4 Dead 2
- 2014
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Ingår i: Transactions of the Digital Games Research Association. - 2328-9422. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- In this article we report an autoethnographic study of pickup groups (PUGs) in the game Left 4 Dead 2 (L4D2). The study focuses on how PUGs as social arenas are constituted by their participants and the role game design plays in structuring interaction. We use Goffman’s idea that activities are surrounded by a metaphorical frame together with an understanding of gameplay design patterns in order to analyze inclusion and exclusion, social positions and the relation between the game context and the players’ “wider worlds.” In the case of L4D2 the design pattern of Symbiotic Player Relationships creates a social situation that puts extra pressure on the players to perform well and leads to issues of identity. By negotiating the boundary between their in-game identity, based on gaming skill, and other social relations outside of the game context, players can constitute a more stable game session. The study concludes with the tentative suggestion that positive perceptions of other players’ out-of-game identity can save a game from falling apart, yet negative perceptions of other players’ values and out-of-game identities pose no threat to the game activity.
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| 34715. |
- Linderoth, Jonas, 1970, et al.
(författare)
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Should I stay or should I go? Boundary maintaining mechanisms in Left 4 Dead 2
- 2012
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Ingår i: Proceedings of DiGRA Nordic 2012 Conference: Local and Global: Games in Culture and Society.
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Konferensbidrag (refereegranskat)abstract
- In this paper we report an ethnographic study of Pick Up Groups (PUGs) in the game Left 4 Dead 2. Our aim with the study is to contribute with a deeper understanding of how these new social arenas are constituted by its’ participants and the role game design plays in structuring these encounters. As a deliberate attempt to go beyond the discussion in the game studies field about formalism versus play studies, we use both concepts from micro-sociology as well as concepts from the field of game design as our analytical framework. Our results shows that the dynamics of a PUG can be understood in relation to how players uphold and negotiate the boundary between the their in-game-identity based on their gaming skill and a other social relations outside of the game context.
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| 34716. |
- Linderälv, Christopher, 1986, et al.
(författare)
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A Unifying Perspective on Oxygen Vacancies in Wide Band Gap Oxides
- 2018
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 9:1, s. 222-228
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Tidskriftsartikel (refereegranskat)abstract
- Wide band gap oxides are versatile materials with numerous applications in research and technology. Many properties of these materials are intimately related to defects, with the most important defect being the oxygen vacancy. Here, using electronic structure calculations, we show that the charge transition level (CTL) and eigenstates associated with oxygen vacancies, which to a large extent determine their electronic properties, are confined to a rather narrow energy range, even while band gap and the electronic structure of the conduction band vary substantially. Vacancies are classified according to their character (deep versus shallow), which shows that the alignment of electronic eigenenergies and CTL can be understood in terms of the transition between cavity-like localized levels in the large band gap limit and strong coupling between conduction band and vacancy states for small to medium band gaps. We consider both conventional and hybrid functionals and demonstrate that the former yields results in very good agreement with the latter provided that band edge alignment is taken into account.
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| 34717. |
- Linderälv, Christopher, 1986, et al.
(författare)
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High-Throughput Characterization of Transition Metal Dichalcogenide Alloys: Thermodynamic Stability and Electronic Band Alignment
- 2022
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 34, s. 9364-9372
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Tidskriftsartikel (refereegranskat)abstract
- Alloying offers a way to tune many of the properties of the transition metal dichalcogenide (TMD) monolayers. While these systems in many cases have been thoroughly investigated previously, the fundamental understanding of critical temperatures, phase diagrams, and band edge alignment is still incomplete. Based on first-principles calculations and alloy cluster expansions, we compute the phase diagrams of 72 TMD monolayer alloys and classify the mixing behavior. We show that ordered phases in general are absent at room temperature but that there exist some alloys that have a stable Janus phase at room temperature. Furthermore, for a subset of these alloys, we quantify the band edge bowing and show that the band edge positions for the mixing alloys can be continuously tuned in the range set by the boundary phases.
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| 34718. |
- Linderälv, Christopher, 1986, et al.
(författare)
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Luminescence Quenching via Deep Defect States: A Recombination Pathway via Oxygen Vacancies in Ce-Doped YAG
- 2021
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 33:1, s. 73-80
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Tidskriftsartikel (refereegranskat)abstract
- Luminescence quenching via nonradiative recombination channels limits the efficiency of optical materials such as phosphors and scintillators and therefore has implications for conversion efficiency and device lifetimes. In materials such as Ce-doped yttrium aluminum garnet (YAG:Ce), quenching shows strong dependence on both temperature and activator concentration, limiting the fabrication of high-intensity white-light emitting diodes with high operating temperatures. Here, we reveal by means of first-principles calculations an efficient recombination mechanism in YAG:Ce that involves oxygen vacancies and gives rise to thermally activated concentration quenching. We demonstrate that the key requirements for this mechanism to be active are localized states with strong electron-phonon coupling. These conditions are commonly found for intrinsic defects such as anion vacancies in wide band gap materials. The present findings are therefore relevant to a broad class of optical materials and shine light on thermal quenching mechanisms in general.
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| 34719. |
- Linderälv, Christopher, 1986, et al.
(författare)
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Vibrational signatures for the identification of single-photon emitters in hexagonal boron nitride
- 2021
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 103:11
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Tidskriftsartikel (refereegranskat)abstract
- Color centers in hexagonal boron nitride (h-BN) are among the brightest emission centers known, yet the origins of these emission centers are not well understood. Here, using first-principles calculations in combination with the generating function method, we systematically elucidate the coupling of specific defects to the vibrational degrees of freedom. We show that the line shape of many defects exhibits strong coupling to high frequency phonon modes and that CN, CB, CB-CN dimer, and VB can be associated with experimental line shapes. Our detailed theoretical study serves as a guide to identify optically active defects in h-BN that can suit specific applications in photonic-based quantum technologies, such as single photon emitters, hybrid spin-photon interfaces, or spin-mechanics interfaces.
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| 34720. |
- Lindfeldt, Erik, 1982, et al.
(författare)
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Estimation of microscale strain fields in a pearlitic steel using DIC and in-situ SEM
- 2014
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Ingår i: Proceedings of 14th European Mechanics of Materials Conference - EMMC14.
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Konferensbidrag (refereegranskat)abstract
- In this contribution the Digital Image Correlation (DIC) technique is used to identify strain fields within a pearlitic microstructure from in-situ obtained SEM images. Typically this is done using a synthetic speckle but in this study the intensity field variations, related to themicrostructure of pearlite, are used as a natural speckle.As a means to avoid subsets with inadequate information content (in terms of intensity field variations) a tracebility criterion is introduced. This criterion is based on the eigenvalues of the Hessian of the autocorrelation function. A pertaining algorithm, which can be used to identify high quality subsets (in terms of tracebility) within a certain Region Of Interest (ROI),is also presented. By using the obtained irregular subsets grids together with synthetically deformed images thedisplacement and deformation gradient errors (both local and average) are studied as a function of the applied loading for various subset sizes.
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