| 1. |
- Adolfsson, Caroline, et al.
(författare)
-
Collaborative introspection as a methodological tool of reflexivity - from multidisciplinary to transdisciplinary co-production
- 2021
-
Ingår i: International Transdisciplinarity Conference (ITD21), 13-17 Sept: Creating spaces and cultivating mindsets for learning and experimentation.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper explores reflexivity through "collaborative introspection" as a methodological tool for transcending a multidisciplinary dialogue and achieving transdisciplinary co-production of knowledge. Reflexivity is argued to be applicable for critically addressing assumptions and ideologies of the research team (Popa et al., 2015), joint problem framing (Pearce & Ejderyan, 2019), experimentation (Popa et al., 2015), or more generally as a focal area to be used for addressing challenges in transdisciplinary projects (Jahn, et al., 2012; Polk, 2015). However, discussions on reflexivity rarely place focus on how a reflexive dialogue can be used to gather empirical material in a collaborative manner, making use of the participating researchers’ subjectivity, personal experiences and understandings of a specific topic. The authors of this text are part of a transdisciplinary research team exploring the role of tourism in multicultural societies. The team involves researchers from the fields of design, marketing, tourism studies, human-computer interaction, and migration studies. In the project we collaborate with each other across disciplines in different case studies. However, we have experienced a tendency to fall back into our disciplinary silos, where we explore the same topic from our own disciplinary lenses. As an attempt to bring ourselves together we decided to go personal. Instead of looking at the role of tourism in multicultural societies from our disciplinary viewpoints, we dug into our memories of acting as tourists ourselves in a reflective session. More specifically, inspired by the tool Tell your story by means of an object (td-net, 2021), we shared and reflected upon our own tourism experiences through our core project concepts, which are diversity, inclusivity and integration. The dialogue that emerged forced us to focus on our research topic not as researchers who are expected to maintain objectivity but rather as individuals allowing ourselves to be subjective. This created a feeling of working ‘together’ instead of ‘with’ each other. The reflections created genuine and honest dialogue highlighting our national, cultural, gender and racial differences. The differences and similarities of our personal experiences depend on the social categories and identities that we are part of. Thus, by bringing our personal stories as empirical material, we created an opportunity to listen to each other beyond our disciplinary boundaries. It made us understand the layers of hierarchy, privilege and disadvantages that we face in our lives as individuals, and to understand instances of inclusion and exclusion in tourism at a deeper level. From our experience, we propose what we term "collaborative introspection" as a reflexive methodological tool for transdisciplinary research and practice. Collaborative introspection exercises challenge the commonly held idea of neutrality. It can be used as a tool for a transdisciplinary group to come together, transform thoughts and develop empathy and ethics in research. References: Jahn, T., Bergmann, M. & Keil, F. (2018). Transdisciplinarity: between mainstreaming and marginalization, Ecological Economics 79 Pearce, B. J., & Ejderyan, O. (2020). Joint problem framing as reflexive practice: honing a transdisciplinary skill. Sustainability science, 15(3), 683-698. Polk, M. (2015). Transdisciplinary co-production: Designing and testing a transdisciplinary research framework for societal problem solving. Futures, 65, 110-122. Popa, F., Guillermin, M., & Dedeurwaerdere, T. (2015). A pragmatist approach to transdisciplinarity in sustainability research: From complex systems theory to reflexive science. Futures, 65, 45-56. Td-net (2021, April 7). Tell your Story by Means of an Object. Retrieved from: https://naturalsciences.ch/co-producing-knowledge-explained/methods/td-net_toolbox/_tell_your_story_by_means_of_an_object_
|
|
| 2. |
- Backman, Anders, et al.
(författare)
-
easyADL – Wearable Support System for Independent Life despite Dementia
- 2006
-
Ingår i: ACM CHI 2006 Workshop onDesigning Technology for People with Cognitive Impairments.
-
Konferensbidrag (refereegranskat)abstract
- This position paper outlines the easyADL project, a two-year project investigating the possibility of using wearable technology to assist people suffering the dementia disease in performing Activities of Daily Living (ADL). An introduction to the egocentric interaction modeling framework is provided and the virtual reality based development methodology is discusssed.
|
|
| 3. |
- Balachandramurthi, Arun Ramanathan, 1989-, et al.
(författare)
-
Anisotropic fatigue properties of Alloy 718 manufactured by Electron Beam Powder Bed Fusion
- 2020
-
Ingår i: International Journal of Fatigue. - : Elsevier. - 0142-1123 .- 1879-3452. ; 141
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, Alloy 718 specimens manufactured by Electron Beam Powder Bed Fusion process are subjected to two different post-treatments to have different microstructural features. Low cycle fatigue testing has been performed both parallel and transverse to the build direction. EB-PBF Alloy 718 exhibits anisotropic fatigue behaviour; the fatigue life is better along the parallel direction compared to the transverse direction. The anisotropy in fatigue life is related to the anisotropy in the Young’s modulus. The pseudo-elastic stress vs. fatigue life approach is presented as a potential solution to handle anisotropy in fatigue life assessment of additively manufactured engineering components. © 2020 The Authors
|
|
| 4. |
- Balachandramurthi, Arun Ramanathan, et al.
(författare)
-
On the microstructure of laser beam powder bed fusion alloy 718 and its influence on the low cycle fatigue behaviour
- 2020
-
Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 13:22, s. 1-21
-
Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing of Alloy 718 has become a popular subject of research in recent years. Understanding the process-microstructure-property relationship of additively manufactured Alloy 718 is crucial for maturing the technology to manufacture critical components. Fatigue behaviour is a key mechanical property that is required in applications such as gas turbines. Therefore, in the present work, low cycle fatigue behaviour of Alloy 718 manufactured by laser beam powder bed fusion process has been investigated. The material was tested in as-built condition as well as after two different thermal post-treatments. Three orientations with respect to the building direction were tested to evaluate the anisotropy. Testing was performed at room temperature under controlled amplitudes of strain. It was found that defects, inclusions, strengthening precipitates, and Young’s modulus influence the fatigue behaviour under strain-controlled conditions. The strengthening precipitates affected the deformation mechanism as well as the cycle-dependent hardening/softening behaviour. The defects and the inclusions had a detrimental effect on fatigue life. The presence of Laves phase in LB-PBF Alloy 718 did not have a detrimental effect on fatigue life. Young’s modulus was anisotropic and it contributed to the anisotropy in strain-life relationship. Pseudo-elastic stress vs. fatigue life approach could be used to handle the modulus-induced anisotropy in the strain-life relationship.
|
|
| 5. |
- Emile-Geay, J., et al.
(författare)
-
Data Descriptor: A global multiproxy database for temperature reconstructions of the Common Era
- 2017
-
Ingår i: Scientific Data. - : Springer Science and Business Media LLC. - 2052-4463. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high-and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python. Since the pioneering work of D'Arrigo and Jacoby1-3, as well as Mann et al. 4,5, temperature reconstructions of the Common Era have become a key component of climate assessments6-9. Such reconstructions depend strongly on the composition of the underlying network of climate proxies10, and it is therefore critical for the climate community to have access to a community-vetted, quality-controlled database of temperature-sensitive records stored in a self-describing format. The Past Global Changes (PAGES) 2k consortium, a self-organized, international group of experts, recently assembled such a database, and used it to reconstruct surface temperature over continental-scale regions11 (hereafter, ` PAGES2k-2013'). This data descriptor presents version 2.0.0 of the PAGES2k proxy temperature database (Data Citation 1). It augments the PAGES2k-2013 collection of terrestrial records with marine records assembled by the Ocean2k working group at centennial12 and annual13 time scales. In addition to these previously published data compilations, this version includes substantially more records, extensive new metadata, and validation. Furthermore, the selection criteria for records included in this version are applied more uniformly and transparently across regions, resulting in a more cohesive data product. This data descriptor describes the contents of the database, the criteria for inclusion, and quantifies the relation of each record with instrumental temperature. In addition, the paleotemperature time series are summarized as composites to highlight the most salient decadal-to centennial-scale behaviour of the dataset and check mutual consistency between paleoclimate archives. We provide extensive Matlab code to probe the database-processing, filtering and aggregating it in various ways to investigate temperature variability over the Common Era. The unique approach to data stewardship and code-sharing employed here is designed to enable an unprecedented scale of investigation of the temperature history of the Common Era, by the scientific community and citizen-scientists alike.
|
|
| 6. |
|
|
| 7. |
- Jalaliniya, Shahram, et al.
(författare)
-
A Wearable Personal Assistant for Surgeons : Design, Evaluation, and Future Prospects
- 2017
-
Ingår i: EAI Endorsed Transactions on Pervasive Health and Technology. - : EAI. - 2411-7145. ; 3:12
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present our body-and-mind-centric approach for the design of wearable personal assistants (WPAs) motivated by the fact that such devices are likely to play an increasing role in everyday life. We also report on the utility of such a device for orthopedic surgeons in hospitals. A prototype of the WPA was developed on Google Glass for supporting surgeons in three di↵erent scenarios: (1) touch-less interaction with medical images, (2) tele-presence during surgeries, and (3) mobile access to Electronic Patient Records (EPR) during ward rounds. We evaluated the system in a clinical simulation facility and found that while the WPA can be a viable solution for touch-less interaction and remote collaborations during surgeries, using the WPA in the ward rounds might interfere with social interaction between clinicians and patients. Finally, we present our ongoing exploration of gaze and gesture as alternative input modalities for WPAs inspired by the hospital study.
|
|
| 8. |
- Jalaliniya, Shahram, et al.
(författare)
-
Symbiotic Attention Management in the Context of Internet of Things
- 2017
-
Ingår i: UbiComp '17 Proceedings of the 2017 ACM International Joint Conference on Pervasive and Ubiquitous Computing and Proceedings of the 2017 ACM International Symposium on Wearable Computers. - New York, NY, USA : Association for Computing Machinery (ACM). ; , s. 941-946
-
Konferensbidrag (refereegranskat)abstract
- In this position paper we stress the need for considering the nature of human attention when designing future potentially interruptive IoT and propose to let IoT devices share attention-related data and collaborate on the task of drawing human attention in order to achieve higher quality attention management with less overall system resources. Finally, we categorize some existing strategies for drawing people’s attention according to a simple symbiotic (human- machine) attention management framework.
|
|
| 9. |
- Jernsand, Eva Maria, 1967, et al.
(författare)
-
Tourism memories : a collaborative reflection on inclusion and exclusion
- 2023
-
Ingår i: Tourism Recreation Resarch. - : Taylor & Francis. - 0250-8281 .- 2320-0308. ; 48:6, s. 820-830
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to explore how people’s differentiated privileged and marginalised positions in society create instances of inclusion and exclusion in tourism. Eight authors utilised their diverse disciplinary and theoretical bases to engage in individual autoethnography and collaborative reflections of their personal experiences of being tourists and hosts. Through our Western and non-Western, White and non-White experiences, we reveal experiences from a multitude of perspectives, and problematise the dominant White racial frame. The methodology illustrates unquestioned privileges and feelings of discomfort when personally faced with exclusionary practices and creates an understanding of how individuals have different experiences of enchantment and the tourist gaze. The experience of marginalisation is serial and dialectical, which illustrates the complexity of tourism. The paper contributes to an enhanced and multifaceted understanding of tourism experiences and proposes measures to reveal issues of exclusion. Also, the use of autoethnography and collaborative reflection as methodological tools provide opportunities for researchers and practitioners to engage in reflexive conversation on discriminatory practices, and how they hinder certain individuals and groups from enjoying tourism products and services.
|
|
| 10. |
- Kadish, David, et al.
(författare)
-
Towards Situation Awareness and Attention Guidance in a Multiplayer Environment using Augmented Reality and Carcassonne
- 2022
-
Ingår i: CHI PLAY 2022 - Extended Abstracts of the 2022 Annual Symposium on Computer-Human Interaction in Play. - New York, NY, USA : ACM. - 9781450392112 ; , s. 133-139
-
Konferensbidrag (refereegranskat)abstract
- Augmented reality (AR) games are a rich environment for researching and testing computational systems that provide subtle user guidance and training. In particular computer systems that aim to augment a user's situation awareness benefit from the range of sensors and computing power available in AR headsets. The main focus of this work-in-progress paper is the introduction of the concept of the individualized Situation Awareness-based Attention Guidance (SAAG) system used to increase humans' situating awareness and the augmented reality version of the board game Carcassonne for validation and evaluation of SAAG. Furthermore, we present our initial work in developing the SAAG pipeline, the generation of game state encodings, the development and training of a game AI, and the design of situation modeling and eye-tracking processes.
|
|
| 11. |
- Leland, Caroline, et al.
(författare)
-
Missing Rings, Synchronous Growth, and Ecological Disturbance in a 36-Year Pitch Pine (Pinus rigida) Provenance Study
- 2016
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:5
-
Tidskriftsartikel (refereegranskat)abstract
- Provenance studies are an increasingly important analog for understanding how trees adapted to particular climatic conditions might respond to climate change. Dendrochronological analysis can illuminate differences among trees from different seed sources in terms of absolute annual growth and sensitivity to external growth factors. We analyzed annual radial growth of 567 36-year-old pitch pine (Pinus rigida Mill.) trees from 27 seed sources to evaluate their performance in a New Jersey Pine Barrens provenance experiment. Unexpectedly, missing rings were prevalent in most trees, and some years-1992, 1999, and 2006-had a particularly high frequency of missing rings across the plantation. Trees from local seed sources (<55 km away from the plantation) had a significantly smaller percentage of missing rings from 1980-2009 (mean: 5.0%), relative to northernmost and southernmost sources (mean: 9.3% and 7.9%, respectively). Some years with a high frequency of missing rings coincide with outbreaks of defoliating insects or dry growing season conditions. The propensity for missing rings synchronized annual variations in growth across all trees and might have complicated the detection of potential differences in interannual variability among seed sources. Average ring width was significantly larger in seed sources from both the southernmost and warmest origins compared to the northernmost and coldest seed sources in most years. Local seed sources had the highest average radial growth. Adaptation to local environmental conditions and disturbances might have influenced the higher growth rate found in local seed sources. These findings underscore the need to understand the integrative impact of multiple environmental drivers, such as disturbance agents and climate change, on tree growth, forest dynamics, and the carbon cycle.
|
|
| 12. |
- Lundbäck, Andreas, et al.
(författare)
-
Modeling and Experimental Measurement with Synchrotron Radiation of Residual Stresses in Laser Metal Deposited Ti-6Al-4V
- 2016
-
Ingår i: Proceedings of the 13th World Conference on Titanium. - Hoboken, NJ, USA : John Wiley & Sons, Inc.. - 9781119293668 - 9781119296126 ; , s. 1279-1282
-
Konferensbidrag (refereegranskat)abstract
- There are many challenges in producing aerospace components by additive manufacturing (AM). One of them is to keep the residual stresses and deformations to a minimum. Another one is to achieve the desired material properties in the final component. A computer model can be of great assistance when trying to reduce the negative effects of the manufacturing process. In this work a finite element model is used to predict the thermo-mechanical response during the AM-process. This work features a physically based plasticity model coupled with a microstructure evolution model for the titanium alloy Ti -6Al-4V. Residual stresses in AM components were measured non-destructively using high-energy synchrotron X-ray diffraction on beam line ID15A at the ESRF, Grenoble. The results are compared with FE model predictions of residual stresses. During the process, temperatures and deformations was continuously measured. The measured and computed thermal history agrees well. The result with respect to the deformations agrees well qualitatively. Meaning that the change in deformation in each sequence is well predicted but there is a systematic error that is summing so that the quantitative agreement is lost.
|
|
| 13. |
|
|
| 14. |
- Lundbäck, Andreas, et al.
(författare)
-
Modelling and Simulation of Metal Deposition on a Ti-6al-4v Plate
- 2015
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There are many challenges in producing aerospace components by metal deposition (MD). One of them is to keep the residual stresses and deformations to a minimum. Anotherone is to achieve the desired material properties in the final component. A computer model can be of great assistance when trying to reduce the negative effects of the manufacturing process. In this work a finite element model is used to predict the thermo-mechanical response during the MD-process. This work features a pysically based plasticity model coupled with a microstructure evolution model for the titanium alloy Ti-6Al-4V. A thermally driven microstructure model is used to derive the evolution of the non-equilibrium compositions of α-phases and β-phase. Addition of material is done by activation of elements. The method is taking large deformations into consideration and adjusts the shape and position of the activated elements. This is particularilly important when adding material onto thin and flexible structures. The FE-model can be used to evaluate the effect of different welding sequenses. Validation of the model is performed by comparing measured deformations, strains, residual stresses and temperatures with the computed result. The deformations, strains and temepratures are measured during the process. The deformations are measured with a LVDT-gauge at one location. The strains are measured with a strain gauge at the same location as the deformations. The temperature is measured at five locations, close to the weld and with an increasing distance of one millimeter between each thermo couple. The residual stresses in MD component were measured non-destructively using high-energy synchrotron X-ray diffraction on beam line ID15A at the ESRF, Grenoble.
|
|
| 15. |
- Neikter, Magnus, 1988-, et al.
(författare)
-
Fatigue Crack Growth of Electron Beam Melted Ti-6Al-4V in High-Pressure Hydrogen
- 2020
-
Ingår i: Materials. - : MDPI. - 1996-1944. ; 13:6
-
Tidskriftsartikel (refereegranskat)abstract
- Titanium-based alloys are susceptible to hydrogen embrittlement (HE), a phenomenon that deteriorates fatigue properties. Ti-6Al-4V is the most widely used titanium alloy and the effect of hydrogen embrittlement on fatigue crack growth (FCG) was investigated by carrying out crack propagation tests in air and high-pressure H2 environment. The FCG test in hydrogen environment resulted in a drastic increase in crack growth rate at a certain Δ K, with crack propagation rates up to 13 times higher than those observed in air. Possible reasons for such behavior were discussed in this paper. The relationship between FCG results in high-pressure H2 environment and microstructure was investigated by comparison with already published results of cast and forged Ti-6Al-4V. Coarser microstructure was found to be more sensitive to HE. Moreover, the electron beam melting (EBM) materials experienced a crack growth acceleration in-between that of cast and wrought Ti-6Al-4V.
|
|
| 16. |
- Neikter, Magnus, 1988-, et al.
(författare)
-
Tensile properties of 21-6-9 austenitic stainless steel built using laser powder-bed fusion
- 2021
-
Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 14:15
-
Tidskriftsartikel (refereegranskat)abstract
- Alloy 21-6-9 is an austenitic stainless steel with high strength, thermal stability at high temperatures, and retained toughness at cryogenic temperatures. This type of steel has been used for aerospace applications for decades, using traditional manufacturing processes. However, limited research has been conducted on this alloy manufactured using laser powder-bed fusion (LPBF). Therefore, in this work, a design of experiment (DOE) was performed to obtain optimized process parameters with regard to low porosity. Once the optimized parameters were established, horizontal and vertical blanks were built to investigate the mechanical properties and potential anisotropic behavior. As this alloy is exposed to elevated temperatures in industrial applications, the effect of elevated temperatures (room temperature and 750◦C) on the tensile properties was investigated. In this work, it was shown that alloy 21-6-9 could be built successfully using LPBF, with good properties and a density of 99.7%, having an ultimate tensile strength of 825 MPa, with an elongation of 41%, and without any significant anisotropic behavior. © 2021 by the authors.
|
|
| 17. |
- Ovesdotter Alm, Cecilia, et al.
(författare)
-
Workshop on Invisible AI-driven HCI Systems : When, Why and How
- 2020
-
Ingår i: NordiCHI '20: Proceedings of the 11th Nordic Conference on Human-Computer Interaction, Extended Abstract. - New York, NY, USA : ACM Digital Library. - 9781450375795
-
Konferensbidrag (refereegranskat)abstract
- The InvisibleAI (InvAI’20) workshop aims to systematically discuss a growing class of interactive systems that invisibly remove some decision-making tasks away from humans to machines, based on recent advances in artificial intelligence (AI), data science, and sensor or actuation technology. While the interest in the affordances as well as the risks of hidden pervasive AI are high on the agenda in public debate, discussion on the topic is needed within the human-computer interaction (HCI) community. In particular, we want to gather insights, ideas, and models for approaching the use of barely noticeable AI decision-making in systems design from a human-centered perspective, so as to make the most out of the automated systems and algorithms that support human activity both as designers and users. Concurrently, these systems should safeguard that humans remain in charge when it counts (high stakes decisions, privacy, monitoring lack of explainability and fairness, etc.). What to automate and what not to automate is often a system designer’s choice [8]. By taking the established concept of explicit interaction between a system and its user as a point of departure, and inviting authors to provide examples from their own research, we aim to stimulate dynamic discussion while keeping the workshop concrete and system design-focused. The workshop especially directs itself to participants from the interaction design, AI, and HCI communities. The targeted scientific outcome of the workshop is an up-to-date ontology of invisible AI-HCI systems and hybrid human-AI collaboration mechanisms, and approaches. Additionally, we expect that the workgroups and the roundtables will provide starting points shaping continued discussions, new collaborations, and innovative scientific contributions that springboard from the workgroups’ findings. The focus of the proposed workshop involves the bridging of two spaces of computational research that impact user experiences and societal domains (HCI and AI). Thus, the proposed workshop topic aligns well with the theme of this year’s NordiCHI conference which is Shaping Experiences, Shaping Society.
|
|
| 18. |
- Pederson, Thomas, et al.
(författare)
-
A situative space model for distributed multimodal interaction
- 2008
-
Konferensbidrag (refereegranskat)abstract
- This workshop paper presents a body-centered model of human-environment interaction based on proximal and perceptional relationships between the human actor and objects of interest (physical objects, virtual objects, and mediators). The model is applied to a real world scenario and also discussed as a tool for designing a distributed multimodal interaction infrastructure.
|
|
| 19. |
- Pederson, Thomas, et al.
(författare)
-
A situative space model for mobile mixed-reality computing
- 2011
-
Ingår i: IEEE pervasive computing. - New York, NY : IEEE Computer Society. - 1536-1268 .- 1558-2590. ; 10:4, s. 73-83
-
Tidskriftsartikel (refereegranskat)abstract
- This article proposes a situative space model that links the physical and virtual realms and sets the stage for complex human-computer interaction defined by what a human agent can see, hear, and touch, at any given point in time.
|
|
| 20. |
- Pederson, Thomas, et al.
(författare)
-
Framing the Next-Generation ‘Desktop’ using Proximity and Human Perception
- 2008
-
Ingår i: ACM CHI 2008 Conference Workshop on User Interface Description Languages for Next-Generation User Interfaces.
-
Konferensbidrag (refereegranskat)abstract
- Personal computing, and therefore Human-Computer Interaction (HCI), is becoming a seamlessly integrated part of everyday activity down to the point where "computing" is inseparable from "activity". A modelling problem occurs in these emerging mobile and ubiquitous computing situations because it is hard to determine the spatial and operational limits of an ongoing activity, for the human performing the activity, for the computer system monitoring and/or supporting it, as well as for the modeller observing it. Also, it is an open issue how to model the causal relations between physical (real world) and virtual (digital world) phenomena that these "intelligent environments" can be programmed to maintain, whether defined by software engineers or the end-users themselves. We propose a modeling framework that addresses the above mentioned issues and present our initial attempts to create a User Interface Description Language (UIDL) based on the framework.
|
|
| 21. |
- Pederson, Thomas, 1971-
(författare)
-
From Conceptual Links to Causal Relations — Physical-Virtual Artefacts in Mixed-Reality Space
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a set of concepts and a general design approach for designing Mixed Reality environments based on the idea that the physical (real) world and the virtual (digital) world are equally important and share many properties. Focus is on the design of a technology infrastructure intended to relieve people from some of the extra efforts currently needed when performing activities that make heavy use of both worlds. An important part of the proposed infrastructure is the idea of creating Physical-Virtual Artefacts, objects manifested in the physical and the virtual world at the same time.The presented work challenges the common view of Human-Computer Interaction as a research discipline mainly dealing with the design of “user interfaces” by proposing an alternative or complementary view, a physical-virtual design perspective, abstracting away the user interface, leaving only physical and virtual objects. There are at least three motives for adopting such a design perspective: 1) people well acquainted with specific (physical and virtual) environments are typically more concerned with the manipulation of (physical and virtual) objects than the user interface through which they are accessed. 2) Such a design stance facilitates the conceptualisation of objects that bridge the gap between the physical and the virtual world. 3) Many physical and virtual objects are manifested in both worlds already today. The existing conceptual link between these physical and virtual objects has only to be complemented with causal relations in order to reduce the costs in crossing the border between the physical and the virtual world.A range of concepts are defined and discussed at length in order to frame the design space, including physical-virtual environment gap, physical-virtual activity, physical-virtual artefact, and physical-virtual environment.Two conceptual models of physical-virtual space are presented as a result of adopting the physical-virtual design perspective: for the analysis of object logistics in the context of physical-virtual activities, and for describing structural properties of physical-virtual space respectively. A prototype system offering some degree of physical-virtual infrastructure is also presented.
|
|
| 22. |
- Pederson, Thomas, et al.
(författare)
-
Towards a model for egocentric interaction with physical and virtual objects
- 2010
-
Ingår i: Proceedings of the 6th Nordic Conference on Human-Computer Interaction. - New York, USA : ACM Press. - 9781605589343 ; , s. 755-758
-
Konferensbidrag (refereegranskat)abstract
- Designers of mobile context-aware systems are struggling with the problem of conceptually incorporating the real world into the system design. We present a body-centric modeling framework (as opposed to device-centric) that incorporates physical and virtual objects of interest on the basis of proximity and human perception, framed in the context of an emerging "egocentric" interaction paradigm.
|
|
| 23. |
- Pederson, Thomas, et al.
(författare)
-
Towards an activity-aware wearable computing platform based on an egocentric interaction model
- 2007
-
Ingår i: Proceedings of the 4th International Symposium on Ubiquitous Computing Systems. - Berlin/Heidelberg : Springer Berlin/Heidelberg. - 9783540767718 ; , s. 211-227
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we present our egocentric interaction model for recognizing and supporting everyday human activities. We explain how it allows designers of ubiquitous computing systems to view physical (real) and virtual (digital) objects as residing in one single space and how sets of objects in the vicinity of a specific human actor can be classified based on human perceptual characteristics such as what can be observed and what can be manipulated. We also propose a wearable computer architecture that is based on the egocentric interaction model which potentially could facilitate the development of Ubiquitous Computing applications by letting an operating system take care of maintaining communication with worn and instrumented sensors as well as computing devices. Finally, we present our first steps in implementing an activity-aware wearable support system for people suffering mild dementia based on the proposed model and architecture.
|
|
| 24. |
- Rashid, Md. Jayedur, 1979-
(författare)
-
Extending a networked robot system to include humans, tiny devices, and everyday objects
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In networked robot systems (NRS), robots and robotic devices are distributed in the environment; typically tasks are performed by cooperation and coordination of such multiple networked components. NRS offer advantages over monolithic systems in terms of modularity, flexibility and cost effectiveness, and they are thus becoming a mainstream approach to the inclusion of robotic solutions in everyday environments. The components of a NRS are usually robots and sensors equipped with rich computational and communication facilities. In this thesis, we argue that the capabilities of a NRS would greatly increase if it could also accommodate among its nodes simpler entities, like small ubiquitous sensing and actuation devices, home appliances, or augmented everyday objects. For instance, a domestic robot needs to manipulate food items and interact with appliances. Such a robot would benefit from the ability to exchange information with those items and appliances in a direct way, in the same way as with other networked robots and sensors. Combining such highly heterogeneous devices inside one NRS is challenging, and one of the major challenges is to provide a common communication and collaboration infrastructure. In the field of NRS, this infrastructure is commonly provided by a shared middleware. Unfortunately, current middlewares lack the generality needed to allow heterogeneous entities such as robots, simple ubiquitous devices and everyday objects to coexist in the same system. In this thesis we show how an existing middleware for NRS can be extended to include three new types of “citizens” in the system, on peer with the other robots. First, we include computationally simple embedded devices, like ubiquitous sensors and actuators, by creating a fully compatible tiny version of the existing robotic middleware. Second, we include augmented everyday objects or home appliances which are unable to run the middleware on board, by proposing a generic design pattern based on the notion of object proxy. Finally,we go one step further and include humans as nodes in the NRS by defining the notion of human proxy. While there exist a few other NRS which are able to include both robots and simple embedded devices in the same system, the use of proxies to include everyday objects and humans in a generic way is a unique feature of this work. In order to verify and validate the above concepts, we have implemented them in the Peis-Ecology NRS model. We report a number of experiments based on this implementation, which provide both quantitative and qualitative evaluations of its performance, reliability, and interoperability.
|
|
| 25. |
- Squillaci, Linda, et al.
(författare)
-
Extending powder particle size distribution of laser powder bed fusion Ti-6Al-4V : investigation of single tracks and multilayer experiments
- 2023
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper explores the effects of varying process parameters (i.e., laser power, laser scanning speed, hatch distance) on the characteristics of single tracks, triple tracks and cubes, in order to provide answers to Research Question 1. A full factorial DoE approach was adopted to produce the experiments. Data was extracted from different sources to find correlations between tracks and multilayer geometries. A digital microscope was used to obtain height profiles, whilst polished/etched cross sections cut parallel to the build direction were imaged using a LOM to obtain measurements of track height, width, melt pool depth, subsurface porosity and residual defect content in cubes. Track height was found to exceed the recoated value of 70μm for both single and triple tracks. The width of single tracks showed a clear upward trend when displayed against VED, showing a lateral expansion as energy input increased. It was also revealed that single tracks expand laterally as they grow above the substrate, indicating swelling. The melt pool depth showed a steady upward trend when plotted against LED, though less systematic than track width. A martensitic microstructure was detected, with hierarchical α’ needles growing at prescribed crystallographic directions within vertical prior-β grains. A large portion of spatter particles and unmelted powder granules were detected on the substrate and tracks, with many accumulating on the side of the tracks forming a denudation zone.
|
|
| 26. |
- Surie, Dipak, et al.
(författare)
-
A Smart Home Experience using Egocentric Interaction Design Principles
- 2012
-
Ingår i: 15TH IEEE International Conference On Computational Science And Engineering (CSE 2012) / 10TH IEEE/IFIP International Conference On Embedded And Ubiquitous Computing (EUC 2012). - 9781467351652 ; , s. 656-665
-
Konferensbidrag (refereegranskat)abstract
- The landscape of ubiquitous computing comprising of numerous interconnected computing devices seamlessly integrated within everyday environments introduces a need to do research beyond human-computer interaction: in particular incorporate human-environment interaction. While the technological advancements have driven the field of ubiquitous computing, the ultimate focus should center on human agents and their experience in interacting with ubiquitous computing systems offering smart services. This paper describes egocentric interaction as a human body-centered interaction paradigm for framing human-environment interaction using proximity and human perception. A smart home environment capable of supporting physical-virtual activities and designed according to egocentric interaction principles is used for exploring the human experience it offers, yielding positive results as a proof of concept.
|
|
| 27. |
- Surie, Dipak, 1981-, et al.
(författare)
-
Activity recognition based on intra and extra manipulation of everyday objects
- 2007
-
Ingår i: Proceedings of the 4th International Symposium on Ubiquitous Computing Systems. - Berlin/Heidelberg : Springer Berlin/Heidelberg. - 3540767711 - 9783540767718 ; , s. 196-210
-
Konferensbidrag (refereegranskat)abstract
- Recognizing activities based on an actor's interaction with everyday objects is an important research approach within ubiquitous computing. We present a recognition approach which complement objects grabbed or released information with the object's internal state changes (as an effect of intra manipulation) and the object's external state changes with reference to other objects (as an effect of extra manipulation). The concept of Intra manipulation is inspired by the fact that many everyday objects change their internal state when manipulated by the human actor, while extra manipulation is motivated by the fact that humans commonly rearrange the spatial relations between everyday objects as part of their activities. A detailed evaluation of our prototype activity recognition system in virtual reality (VR) environment is presented as a "proof of concept". We have obtained a recognition precision of 92% on the activity-level and 81% on the action-level among 15 everyday home activities. Virtual reality was used as a test-bed in order to speed up the design process of our activity recognition system, allowing us to compensate for the limitations with currently available sensing technologies and to compare the contributions of intra manipulation and extra manipulation for activity recognition.
|
|
| 28. |
- Surie, Dipak, 1981-, et al.
(författare)
-
Activity recognition using an egocentric perspective of everyday objects
- 2007
-
Ingår i: Proceedings of the 4th International Conference on Ubiquitous Intelligence and Computing. - : Springer Berlin/Heidelberg. ; , s. 246-257
-
Konferensbidrag (refereegranskat)abstract
- This paper presents an activity recognition approach based on the tracking of a specific human actor’s current object manipulation actions, complemented by two kinds of situational information: 1) the set of objects that are visually observable (inside the “observable space”) and 2) technically graspable (inside the “manipulable space”). This “egocentric” model is inspired by situated action theory and offers the advantage of not depending on technology for absolute positioning of neither the human nor the objects. Applied in an immersive Virtual Reality environment, the proposed activity recognition approach shows a recognition precision of 89% on the activity-level and 76% on the action-level among 10 everyday home activities.
|
|
| 29. |
- Surie, Dipak, 1981-, et al.
(författare)
-
An activity-centered wearable computing infrastructure for intelligent environment applications
- 2007
-
Ingår i: Proceedings of the International Conference on Embedded and Ubiquitous Computing. - Berlin/Heidelberg : Springer Berlin/Heidelberg. - 9783540770916 ; , s. 456-465
-
Konferensbidrag (refereegranskat)abstract
- There are many research efforts that focus on converting everyday environments into intelligent and computationally active environments that support and enhance the abilities of its occupants in executing their activities. Such environments must have the ability to recognize the activities performed by its occupant, maintain a real-time model of the environment, address the occupant's privacy and personalization issues, and provide interaction capabilities in a way the occupant would with other people. In this paper we present an activity-centered wearable computing infrastructure for designing intelligent environment applications based on the occupant's usage and storage of everyday objects in that environment. Four components namely object manager, situative space monitor, activity recognizer and egocentric interaction manager are introduced and described in detail. A prototypical intelligent home environment capable of supporting 15 Activities of Daily Living with an activity recognition precision of 92% is presented as a "proof of concept" in a virtual reality (VR) simulated home environment.
|
|
| 30. |
- Surie, Dipak, et al.
(författare)
-
Egocentric interaction as a tool for designing ambient ecologies : the case of the easy ADL ecology
- 2012
-
Ingår i: Pervasive and Mobile Computing. - : Elsevier. - 1574-1192 .- 1873-1589. ; 8:4, s. 597-613
-
Tidskriftsartikel (refereegranskat)abstract
- The visions of ambient intelligence demand novel interaction paradigms that enable designers and system developers to frame and manage the dynamic and complex interaction between humans and environments populated with physical (real) and virtual (digital) objects of interest. So far, many proposed approaches have adhered to a device-centric stance when including virtual objects into the ambient ecology; a stance inherited from existing interaction paradigms for mobile and stationary interactive devices. In this article, we introduce egocentric interaction as an alternative approach, taking the human agent's body and mind as the center of reference. We show how this interaction paradigm has influenced both the conception and implementation of the easy ADL ecology, comprising of smart objects, a personal activity-centric middleware attempting to simplify interaction given available resources, ambient intelligence applications aimed at everyday activity support, and a human agent literally in the middle of it all.
|
|
| 31. |
- Surie, Dipak, 1981-
(författare)
-
Egocentric interaction for ambient intelligence
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ambient intelligence refers to the vision of computationally augmented everyday environments that are sensitive, adaptive and responsive to humans and intelligently support their daily lives. Ambient ecologies are the infrastructures of ambient intelligence. To enable system developers to frame and manage the dynamic and complex interaction of humans with ambient ecologies consisting of a mixture of physical (real) and virtual (digital) objects, novel interaction paradigms are needed. Traditional interaction paradigms like the WIMP (windows, icon, menus, and pointing devices) paradigm for desktop computing operate in a closed world, unaware of the physical, social and cultural context. They restrict human perception and action to screen, mouse and keyboard with the assumption that human attention will be fully devoted to interaction with the computer. Emerging interaction paradigms for ambient intelligence are typically centered on specific devices, specific computing environments or specific human capabilities. Also, many of them are driven by technological advancements rather than viewing the human agent as their starting point. A principled, theoretical approach centered in the individual human agent, their situation and activities that are comprehensive and integrated while at the same time instrumental in the design of ambient ecologies has been lacking. This thesis introduces egocentric interaction as an approach towards the modeling of ambient ecologies with the distinguishing feature of taking the human agent’s body, situation and activities as center of reference, as opposed to the more common device-centric approaches in facilitating human-environment interaction. Egocentric interaction is encapsulated in a number of assumptions and principles such as situatedness, the proximity principle, the physical-virtual equity principle, perception and action instead of “input” and “output,” and activity-centeredness. A situative space model is proposed based on some of these principles. It is intended to capture what a specific human agent can perceive and not perceive, reach and not reach at any given moment in time. The situative space model is for the egocentric interaction paradigm what the virtual desktop is for the WIMP interaction paradigm: more or less everything of interest to a specific human agent is assumed and supposed to happen here. In addition, the conception and implementation of the easy ADL ecology based on egocentric interaction, comprising of smart objects, a personal activity-centric middleware, ambient intelligence applications aimed at everyday activity support, and a human agent literally in the middle of it all is described. The middleware was developed to address important challenges in ambient intelligence: (1) tracking and managing smart objects; (2) tracking a human agent’s situative spaces; (3) recognizing human activities and actions; (4) managing and facilitating human-environment interaction; and (5) to ease up the development of ambient intelligence applications. The easy ADL ecology was first simulated in immersive virtual reality, and then set up physically as a living laboratory to evaluate: (1) the technological and technical performance of individual middleware components, (2) to perform a user experience evaluation assessing various aspects of user satisfaction in relation to the support offered by the easy ADL ecology, and (3) to use it as a research test bed for addressing challenges in ambient intelligence. While it is problematic to directly compare the “proof-of-concept” easy ADL ecology with related research efforts, it is clear from the user experience evaluation that the subjects were positive with the services it offered.
|
|
| 32. |
- Surie, Dipak, et al.
(författare)
-
Human cognition as a foundation for the emerging egocentric interaction paradigm
- 2012
-
Ingår i: Human-Computer Interaction: The Agency Perspective. - Berlin/Heidelberg : Springer Berlin/Heidelberg. - 9783642256905 ; , s. 349-374
-
Bokkapitel (refereegranskat)abstract
- This chapter presents an “egocentric interaction paradigm” (EIP) centered on human agents rather than on the notion of user. More specifically, this paradigm is based on perception, action, intention and attention capabilities and limitations of human agents. Traditional and emerging interaction paradigms are typically related to a specific computing environment, devices or human capabilities. The novelty of the proposed approach stems from aiming at developing a comprehensive and integrated theoretical approach, centered on individual human agent. Development in Human-Computer Interaction (HCI) has been closely related to the understanding and utilization of natural human skills and abilities. This work attempts to understand and model a human agent, and in particular their cognitive capabilities in facilitating HCI. The EIP is based on principles like situatedness and embodiment, the physical-virtual equity principle, and the proximity principle. A situative space model built upon our understanding of human cognition is described in detail, followed by our experience in exploring the egocentric interaction paradigm in the easy ADL home.
|
|
| 33. |
- Surie, Dipak, et al.
(författare)
-
Situative space tracking within smart environments
- 2010
-
Ingår i: Proceedings of the 6th International Conference on Intelligent Environments, IE 2010. - Washington, DC, USA : IEEE Computer Society. - 9780769541495 ; , s. 152-157
-
Konferensbidrag (refereegranskat)abstract
- This paper describes our efforts in modeling and tracking a human agent’s situation based on their possibilities to perceive and act upon objects (both physical and virtual) within smart environments. A Situative Space Model is proposed. WLAN signal-strength-based situative space tracking system that positions objects within individual situative spaces (without tracking their absolute positions) distributed across multiple modalities like vision, audio, and touch is presented. As a proof-of-concept, a preliminary evaluation of the tracking system was performed by two subjects within a living-laboratory smart home environment where a global tracking precision of 83.4% and a recall of 88.6% were obtained.
|
|
| 34. |
- Surie, Dipak, 1981-, et al.
(författare)
-
The easy ADL home: A physical-virtual approach to domestic living
- 2010
-
Ingår i: Journal of Ambient Intelligence and Smart Environments. - Amsterdam, The Netherlands : IOS Press. - 1876-1364 .- 1876-1372. ; 2:3, s. 287-310
-
Tidskriftsartikel (refereegranskat)abstract
- Smart environments worthy of the name need to capture, interpret, and support human activities that take place within their realms. Most existing efforts tend to focus on either real world activities or activities taking place in the virtual world accessed through digital devices. However, as digital computation continues to permeate our everyday real world environments, and as the border between physical and digital continues to blur for the human agents acting in these environments, we need system design approaches that can cope with human activities that span the physical-virtual gap. In this paper, we present such an approach and use it for designing a smart home intended to support Activities of Daily Living (ADL). The easy ADL home is designed based on a wearable personal server that runs a personal ADL support middleware and a set of computationally augmented everyday objects within the easy ADL home. An initial qualitative study of the system involving 20 subjects revealed a highly positive attitude (score 4.37 out of 5) towards the system's capability of co-locating and synchronizing physical and virtual events throughout the everyday activity scenarios, while classical usability aspects in particular related to the gesture-based input (score 2.89 out of 5) leaves room for improvement.
|
|
| 35. |
- Surie, Dipak, et al.
(författare)
-
Wireless sensor networking of everyday objects in a smart home environment
- 2008
-
Ingår i: Proceedings of the International Conference on Intelligent Sensors, Sensor Networks and Information Processing, 2008. - : IEEE Computer Society. - 9781424429578 ; , s. 189-194
-
Konferensbidrag (refereegranskat)abstract
- Within a smart home environment the information processing is supposed to be thoroughly integrated into everyday objects. This introduces the need to keep track of the everyday objects and their state changes produced based on the userpsilas interaction with them. Such information is useful in recognizing the userpsilas activities, situations, etc. In this paper we present a ZigBee communication protocol based wireless sensor networking of 42 everyday objects (embedded with 81 simple state change sensors of 8 sensor types) in a living laboratory smart home environment. The system was evaluated in a realistic setup with background noise. The sensing module has shown promising results with an overall system precision of 91.2% and a recall of 98.8% in keeping track of the state changes to everyday objects. The signal strength measure above the acceptable limit of >10 dB to obtain reliable data communication was found to be 97.5% checked at 8 different locations in a home environment. Finally the transmission-reception range was evaluated to be 33 m with a single wall obstruction and 19 m with multiple wall obstruction in an indoor environment.
|
|
| 36. |
- Thalavai Pandian, Karthikeyan, 1985-, et al.
(författare)
-
Elevated-Temperature Tensile Properties of Low-Temperature HIP-Treated EBM-Built Ti-6Al-4V.
- 2022
-
Ingår i: Materials. - : MDPI. - 1996-1944. ; 15:10
-
Tidskriftsartikel (refereegranskat)abstract
- Evaluation of the high-temperature tensile properties of Ti-6Al-4V manufactured by electron beam melting (EBM) and subjected to a low-temperature hot isostatic pressing (HIP) treatment (800 °C) was performed in this study. The high-temperature tensile properties of as-built and standard HIP-treated (920 °C) materials were studied for comparison. Metallurgical characterization of the as-built, HIP-treated materials was carried out to understand the effect of temperature on the microstructure. As the HIP treatments were performed below the β-transus temperature (995 °C for Ti-6Al-4V), no significant difference was observed in β grain width between the as-built and HIP-treated samples. The standard HIP-treated material measured about 1.4×-1.7× wider α laths than those in the modified HIP (low-temperature HIP)-treated and as-built samples. The standard HIP-treated material showed about a 10-14% lower yield strength than other tested materials. At 350 °C, the yield strength decreased to about 65% compared to the room-temperature strength for all tested specimens. An increase in ductility was observed at 150 °C compared to that at room temperature, but the values decreased between 150 and 350 °C because of the activation of different slip systems.
|
|
| 37. |
- Thalavai Pandian, Karthikeyan, 1985-, et al.
(författare)
-
Fatigue behavior of low-temperature hot isostatic pressed electron beam powder bed fusion manufactured Ti-6Al-4 V
- 2023
-
Ingår i: Journal of Alloys and Compounds. - : Elsevier. - 0925-8388 .- 1873-4669. ; 962
-
Tidskriftsartikel (refereegranskat)abstract
- Ti-6Al-4 V finds application in the fan and compressor modules of gas turbine engines due to its high specific strength. Ti-6Al-4 V components manufactured using one of the additive manufacturing (AM) techniques, the electron beam powder bed fusion (PBF-EB) process, has been an active area of research in the past decade. The fatigue life of such PBF-EB built Ti-6Al-4 V components is improved by hot isostatic pressing (HIP) treatment typically performed at about 920 ˚C. The HIP treatment at 920 ˚C results in coarsening of α laths and reduced static strength and therefore a low-temperature HIP treatment is performed at about 800 ˚C to limit the impact on static mechanical properties. In the present work, the low cycle fatigue and fatigue crack growth behavior of such a modified HIP (low-temperature HIP) treated material is assessed and compared with the respective data for the standard HIP-treated material. The modified HIP-treated material has fatigue performance comparable to the standard HIP-treated material. This work suggests that the modified HIP treatment improves the static mechanical properties without significantly impacting the fatigue performance. Also, fatigue life predictions were made from the measured defect size at the crack initiation site using a linear elastic fracture mechanics tool. The life predictions show good agreement with the experimental values for defects greater than the intrinsic crack length, where life is well predicted by large-crack growth methodology.
|
|
| 38. |
- Thalavai Pandian, Karthikeyan, 1985-
(författare)
-
Microstructure and mechanical properties of Ti-6Al-4V manufactured by electron beam powder bed fusion
- 2024
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ti-6Al-4V is an α+β titanium alloy that is widely used in aerospace engine applications due to its high specific strength. Typically, Ti-6Al-4V components are manufactured by conventional manufacturing processes such as castings or forgings. An alternative to conventional manufacturing processes is additive manufacturing (AM), which can be used to manufacture Ti-6Al-4V components, with increased geometrical complexity and potentially lower buy-to-fly ratio. AM material have been shown to have similar static mechanical properties as conventionally manufactured material, but the fatigue properties can be affected by the as-built surface quality and the defects in the AM material. Among several AM processes, the fatigue properties of electron beam powder bed fusion (PBF-EB) manufactured material have been primarily impacted by the as-built surface asperities. Therefore, for fatigue-critical applications, the as-built surfaces are typically removed by post-build treatment, making it challenging to manufacture net-shape geometries directly. Exploring ways to improve the surface quality of PBF-EB manufactured Ti-6Al-4V will reduce the post-finishing needs and increase sustainability. In the current thesis the effect of different contour settings on the as-built surface roughness and fatigue properties have been investigated.The results indicate that increasing the number of contours and melting the contours prior to the hatch positively affect the surface roughness. Among several roughness parameters, the parameter related to surface valley depths has a statistically significant influence on the fatigue life. Moreover, advanced characterization techniques such as x-ray computed tomography are needed to capture the hidden valleys open to the surface. Fatigue life prediction using these hidden valley depths resulted in life estimations comparable to experimental results.After eliminating the as-built surface asperities, defects in the bulk become critical for fatigue, typically addressed by post-build heat treatment such as hot isostatic pressing (HIP). HIP treatment of conventionally cast Ti-6Al-4V is typically performed at 920 ˚C, 100 MPa for 2 hours. This same HIP treatment has also viii been adapted for PBF-EB manufactured Ti-6Al-4V, which results in coarsening of α laths and reduction of yield strength compared to as-built material. Lowering the HIP treatment temperature to 800 ˚C and increasing the pressure to 200 MPa has recently been proven to close the porosity to a high degree while sustaining the as-built yield strength. However, the fatigue performance of the low-temperature HIP treatment needs to be evaluated which is performed in the current thesis. Even though the low-temperature HIP material had the lowest minimum life cycles to failure, the overall fatigue performance is comparable with that of the standard HIP material. Further, in aerospace engine applications, Ti-6Al-4V normally has a maximum operating temperature of 350 ˚C, therefore the elevated temperature tensile performance has also been investigated in this work. At 350 ˚C, the yield strength decreases to about 65% compared to the room temperature strength for all tested materials. An increase in ductility was observed at 150 ˚C compared to that at room temperature, but the ductility decreased between 150 – 350 ˚C because of the activation of different slip systems.
|
|
| 39. |
- Thalavai Pandian, Karthikeyan, 1985-
(författare)
-
Microstructure and mechanical properties of low-temperature hot isostatic pressed Ti-6Al-4V manufactured by electron beam melting
- 2022
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ti-6Al-4V manufactured by electron beam melting Keywords: Additive manufacturing, high-temperature tensile properties, low cycle fatigue, neutron diffraction, fatigue crack growth ISBN: 978-91-89325-27-2 (Printed) 978-91-89325-26-5 (Electronic) Ti-6Al-4V is the most widely used α+β titanium alloy in aerospace engine applications due to its high specific strength. Typically, the alloy is manufactured as castings or forgings and then machined to final geometry. These conventional manufacturing processes do however generate a lot of waste material, whereas additive manufacturing (AM) can potentially produce a near-net-shape geometry directly from the feedstock. In the past decade, electron beam melting (EBM), one of the powder bed fusion techniques, has been widely researched to build Ti[1]6Al-4V components. Still, the as-built material can contain defects such as gas pores that require post-processing, such as hot isostatic pressing (HIP) to produce nearly fully dense components. HIP treatment of conventionally cast Ti-6Al-4V is normally performed at 920 ˚C, 100 MPa for 2 hours. This same HIP treatment has then been adapted also for EBM-manufactured Ti-6Al-4V, which however results in coarsening of α laths and reduction of yield strength. Therefore, finding a more appropriate HIP treatment for this new type of Ti-6Al-4V material, i.e. EBM manufactured, would be of great benefit for the industry. Lowering the HIP treatment temperature to 800 ˚C and increasing the pressure to 200 MPa has recently been proven to close the porosity to a high degree while sustaining the high yield strength. In this thesis, the high-temperature tensile properties of EBM-manufactured Ti[1]6Al-4V subjected to a low-temperature (800 ˚C) HIP treatment were evaluated and compared with standard HIP-treated (920 ˚C) materials. Metallurgical characterization of the as-built, HIP-treated materials have been carried out to understand the effect of temperature on the microstructures. The standard HIP[1]treated material measured about 1.4x - 1.7x wider α laths than those in the low[1]temperature HIP treated and as-built samples, respectively. The standard HIP[1]treated material showed about 10 - 14% lower yield strength than other HIP treated materials. At 350 ˚C the yield strength decreases to about 65% compared to the room temperature strength for all tested materials. An increase in ductility vi programvaran NASGRO där livsförutsägelserna visade god överensstämmelse med experimentella livscykler i de flesta fall. vii Abstract Title: Microstructure and mechanical properties of low-temperature hot isostatic pressed Ti-6Al-4V manufactured by electron beam melting Keywords: Additive manufacturing, high-temperature tensile properties, low cycle fatigue, neutron diffraction, fatigue crack growth ISBN: 978-91-89325-27-2 (Printed) 978-91-89325-26-5 (Electronic) Ti-6Al-4V is the most widely used α+β titanium alloy in aerospace engine applications due to its high specific strength. Typically, the alloy is manufactured as castings or forgings and then machined to final geometry. These conventional manufacturing processes do however generate a lot of waste material, whereas additive manufacturing (AM) can potentially produce a near-net-shape geometry directly from the feedstock. In the past decade, electron beam melting (EBM), one of the powder bed fusion techniques, has been widely researched to build Ti[1]6Al-4V components. Still, the as-built material can contain defects such as gas pores that require post-processing, such as hot isostatic pressing (HIP) to produce nearly fully dense components. HIP treatment of conventionally cast Ti-6Al-4V is normally performed at 920 ˚C, 100 MPa for 2 hours. This same HIP treatment has then been adapted also for EBM-manufactured Ti-6Al-4V, which however results in coarsening of α laths and reduction of yield strength. Therefore, finding a more appropriate HIP treatment for this new type of Ti-6Al-4V material, i.e. EBM manufactured, would be of great benefit for the industry. Lowering the HIP treatment temperature to 800 ˚C and increasing the pressure to 200 MPa has recently been proven to close the porosity to a high degree while sustaining the high yield strength. In this thesis, the high-temperature tensile properties of EBM-manufactured Ti[1]6Al-4V subjected to a low-temperature (800 ˚C) HIP treatment were evaluated and compared with standard HIP-treated (920 ˚C) materials. Metallurgical characterization of the as-built, HIP-treated materials have been carried out to understand the effect of temperature on the microstructures. The standard HIP[1]treated material measured about 1.4x - 1.7x wider α laths than those in the low[1]temperature HIP treated and as-built samples, respectively. The standard HIP[1]treated material showed about 10 - 14% lower yield strength than other HIP treated materials. At 350 ˚C the yield strength decreases to about 65% compared to the room temperature strength for all tested materials. An increase in ductility viii was observed at 150 ˚C compared to that at room temperature, but the ductility decreased between 150 - 350 ˚C because of activation of different slip systems. The low cycle fatigue (LCF) behavior of such a modified HIP (low-temperature HIP) material is assessed at two different strain levels and compared with the corresponding LCF properties for the standard HIP material. Even though the modified HIP material had lowest minimum life cycles to failure, the overall fatigue performance is comparable with that of the standard HIP material. Also, fatigue life predictions were made from the measured defect size at the crack initiation site using NASGRO. The calculated life predictions showed good agreement with the experimental values in most cases. In-situ neutron diffraction measurements on tensile test specimens were conducted, at both room temperature and at 350˚ C, for the standard and modified HIP-treated materials. The objective was to gain essential insights on how the crystal lattice strains relate to the macroscopic strengths in these specific microstructures. This investigation helped to understand the load partitioning between different slip planes and constituent phases in the microstructure at different temperatures.
|
|
| 40. |
- Tobisková, Nicole, et al.
(författare)
-
Augmented Reality for AI-driven Inspection? : A Comparative Usability Study
- 2023
-
Ingår i: Procedia CIRP. - : Elsevier. - 2212-8271 .- 2212-8271. ; 119, s. 734-739
-
Tidskriftsartikel (refereegranskat)abstract
- Inspection in Aerospace industry can, as well as many other industrial applications, benefit from using Augmented Reality (AR) due to its ability to superimpose helpful digital information in 3D, leading to fewer errors and decreased mental demand. However, each AR device has advantages and disadvantages, and not all AR devices are suitable for use in industrial settings. We compare a tripod-fitted-adjustable-arm tablet-based AR solution (Apple iPad Pro) to head-mounted AR (Microsoft HoloLens 2) and a traditional, computer screen-based human-machine interface (HMI), all three designed to guide operators based on previously performed AI-based image analysis. Following an iterative design process with three formative evaluations, a final field test in a real industrial shop floor engaging 6 professional inspectors revealed an overall preference for the tripod-fitted iPad variant which receiving the best scores in most dimensions covered in both a usability-focused SUS questionnaire (score 71) and a NASA-RTLX form focused on perceived workload. More specifically, the tripod-fitted iPad was considered more usable (SUS) than the classic computer display HMI (M=5.83, SD=4.92, p=0.034, N=6); the temporal demand (NASA-RTLX) was considered lower using the iPad compared to both HoloLens 2 and the HMI (M=6.67, SD=4.08, p=0.010; M=10.83, SD=9.70, p=0.040, N=6), respectively.
|
|
| 41. |
- Tobisková, Nicole, et al.
(författare)
-
Head-Mounted Augmented Reality Support for Assemblers of Wooden Trusses
- 2023
-
Ingår i: Procedia CIRP. - : Elsevier. - 2212-8271 .- 2212-8271. ; 119, s. 134-139
-
Tidskriftsartikel (refereegranskat)abstract
- Wooden-house assembly is an area where still a big part of the work is done manually. In this case study, pairs of operators compose large wooden pieces together based on paper-print instructions complemented by visual guidance in the shape of laser marks projected from lasers mounted in the ceiling, based on Computer-aided design (CAD) data. Augmented Reality (AR) head-mounted displays (HMD) offer a unique platform for providing instructions and additional information superimposed in the work environment and thus can provide guidance in a cognitively ergonomic way. A particular advantage compared to other computing platforms is that the operators have free hands and can perform the manual work and follow guidance simultaneously. We present an evaluation of a prototype that dynamically transforms a CAD data file with design and measurements of wooden trusses to be manufactured, into an AR-based guidance system developed in Unity for Microsoft HoloLens 2 devices. We used an iterative participatory design process for prototyping and think-aloud protocol combined with observations for evaluation, involving professional assemblers in different stages of the process. Participants found the solution to potentially save time in their everyday work and simplify the task by offering increased visibility of the marks compared to the existing laser projection. Large-scale deployment of the system is still facing design challenges of which some are also discussed in the paper.
|
|
| 42. |
- Tobisková, Nicole, et al.
(författare)
-
Multimodal Augmented Reality and Subtle Quidance for Industrial Assembly : A Survey and Ideation Method
- 2022
-
Ingår i: Lecture Notes in Computer Science. - Cham : Springer Science+Business Media B.V.. - 0302-9743 .- 1611-3349. ; 13318 LNCS, s. 329-349
-
Tidskriftsartikel (refereegranskat)abstract
- Industrial manual assembly is a relatively established use case for emerging head-mounted Augmented Reality (AR) platforms: operators get visual support in placing pieces depending on where they are in the assembly process. However, is vision the only suitable sensory modality for such guidance? We present a systematic review of previous work done on multimodal guidance and subtle guidance approaches, confirming that explicit visual cues dominate. We then outline a three-step method for generating multisensory guidance ideas intended for real-world task support based on task observation that led to identification of 18 steps in truss assembly, brainstorming AR guidance approaches related to assembly and maintenance, and mapping of brainstorming results to the observed task. We illustrated the use of the method by deploying it on our current mission in producing AR guidance approaches for an industrial partner involved in designing and assembling wooden trusses. In this work, we went beyond the standard visual AR guidance in two ways, 1) by opening for guidance through auditory, tactile, and olfactory sensory channels, 2) by considering subtle guidance as alternative or complement to explicit information presentation. We presented a resulting set of multisensory guidance ideas, each tied to one of the 18 steps in the observed truss assembly task. To mention a few which we intend to investigate further: smell for gradual warning about non-imminent potential hazardous situations; 3D sound to guide operators to location of different tools; thermos-haptics for subtle notifications about contextual events (e.g., happening at other assembly stations). The method presented helped us to explore all modalities and to identify new possibilities. More work is needed to understand how different modalities can be combined and the impact of different modality distractions on task performance. © 2022, Springer Nature Switzerland AG.
|
|
