| 1. |
- Abbas, Nadeem, et al.
(författare)
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Architectural Reasoning Support for Product-Lines of Self-adaptive Software Systems : A Case Study
- 2015
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Ingår i: Software Architecture: 9th European Conference, ECSA 2015, Dubrovnik/Cavtat, Croatia, September 7-11, 201. - Cham : Springer. - 9783319237275 - 9783319237268 ; , s. 20-36
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Konferensbidrag (refereegranskat)abstract
- Software architecture serves as a foundation for the design and development of software systems. Designing an architecture requires extensive analysis and reasoning. The study presented herein focuses on the architectural analysis and reasoning in support of engineering self-adaptive software systems with systematic reuse. Designing self-adaptive software systems with systematic reuse introduces variability along three dimensions; adding more complexity to the architectural analysis and reasoning process. To this end, the study presents an extended Architectural Reasoning Framework with dedicated reasoning support for self-adaptive systems and reuse. To evaluate the proposed framework, we conducted an initial feasibility case study, which concludes that the proposed framework assists the domain architects to increase reusability, reduce fault density, and eliminate differences in skills and experiences among architects, which were our research goals and are decisive factors for a system's overall quality.
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| 2. |
- Abbas, Nadeem, 1980-, et al.
(författare)
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Harnessing Variability in Product-lines of Self-adaptive Software Systems
- 2015
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Ingår i: Proceedings of the 19th International Conference on Software Product Line. - New York, NY, USA : ACM Press. - 9781450336130 ; , s. 191-200
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Konferensbidrag (refereegranskat)abstract
- This work studies systematic reuse in the context of self-adaptive software systems. In our work, we realized that managing variability for such platforms is different compared to traditional platforms, primarily due to the run-time variability and system uncertainties. Motivated by the fact that recent trends show that self-adaptation will be used more often in future system generation and that software reuse state-of-practice or research do not provide sufficient support, we have investigated the problems and possibly resolutions in this context. We have analyzed variability for these systems, using a systematic reuse prism, and identified a research gap in variability management. The analysis divides variability handling into four activities: (1) identify variability, (2) constrain variability, (3) implement variability, and (4) manage variability. Based on the findings we envision a reuse framework for the specific domain and present an example framework that addresses some of the identified challenges. We argue that it provides basic support for engineering self-adaptive software systems with systematic reuse. We discuss some important avenues of research for achieving the vision.
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| 3. |
- Abrahamsen, Rune, et al.
(författare)
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Dynamic Response of Tall Timber Buildings Under Service Load : The DynaTTB Research Program
- 2020
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Ingår i: EURODYN 2020, XI international conferece on structural dynamics. - : National Technical University of Athens. - 9786188507210 ; , s. 4900-4910
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Konferensbidrag (refereegranskat)abstract
- Wind-induced dynamic excitation is becoming a governing design action determin-ing size and shape of modern Tall Timber Buildings (TTBs). The wind actions generate dynamic loading, causing discomfort or annoyance for occupants due to the perceived horizontal sway – i.e. vibration serviceability failure. Although some TTBs have been instrumented and meas-ured to estimate their key dynamic properties (natural frequencies and damping), no systematic evaluation of dynamic performance pertinent to wind loading has been performed for the new and evolving construction technology used in TTBs. The DynaTTB project, funded by the Forest Value research program, mixes on site measurements on existing buildings excited by heavy shakers, for identification of the structural system, with laboratory identification of building elements mechanical features coupled with numerical modelling of timber structures. The goal is to identify and quantify the causes of vibration energy dissipation in modern TTBs and pro-vide key elements to FE modelers.The first building, from a list of 8, was modelled and tested at full scale in December 2019. Some results are presented in this paper. Four other buildings will be modelled and tested in spring 2020.
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| 4. |
- Abrahamsen, Rune, et al.
(författare)
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Dynamic response of tall timber buildings under service load : results from the dynattb research program
- 2023
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Ingår i: World Conference on Timber Engineering 2023 (WCTE 2023). - : Curran Associates, Inc.. - 9781713873297 ; , s. 2907-2914
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Konferensbidrag (refereegranskat)abstract
- Wind-induced dynamic excitation is a governing design action determining size and shape of modern Tall Timber Buildings (TTBs). The wind actions generate dynamic loading, causing discomfort or annoyance for occupants due to the perceived horizontal sway, i.e. vibration serviceability problem. Although some TTBs have been instrumented and measured to estimate their key dynamic properties (eigenfrequencies, mode shapes and damping), no systematic evaluation of dynamic performance pertinent to wind loading had been performed for the new and evolving construction technologies used in TTBs. The DynaTTB project, funded by the ForestValue research program, mixed on site measurements on existing buildings excited by mass inertia shakers (forced vibration) and/or the wind loads (ambient vibration), for identification of the structural system, with laboratory identification of building elements mechanical features, coupled with numerical modelling of timber structures. The goal is to identify and quantify the causes of vibration energy dissipation in modern TTBs and provide key elements to finite element models. This paper presents an overview of the results of the project and the proposed Guidelines for design of TTBs in relation to their dynamic properties.
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| 5. |
- Ali, Sharafat, Associate Professor, 1976-, et al.
(författare)
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Effect of composition on the thermal properties and structure of M-Al-Si-O-N glasses, M = Na, Mg, Ca
- 2024
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Ingår i: Progress in Solid State Chemistry. - : Elsevier. - 0079-6786 .- 1873-1643. ; 74
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Forskningsöversikt (refereegranskat)abstract
- The primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 degrees C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg), crystallization temperature (Tc), glass stability, viscosity, and thermal expansion coefficient (alpha). The findings indicate that increasing the aluminum content leads to higher glass transition, crystallization temperatures, and viscosities. In contrast, fragility values increase with the Al contents, while modifier elements and silicon content influence thermal expansion coefficient values. FTIR analysis revealed that in all glasses, the dominant IR bands are attributed to the presence of Q2 and Q3 silicate units. The effect of Al is observed as a progressive polymerization of the silicate network resulting from the glass-forming role of Al2O3. In most samples, the Q4 silicate mode was also observed, strongly related to the high Al content. Overall, the study shows that the complexity of composition-property correlations where the structural changes affect the properties of Mg/Ca-based oxynitride glasses has potential implications for their use in various technological fields.
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| 6. |
- Amiandamhen, Stephen, 1983-, et al.
(författare)
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Recycling sawmilling wood chips, biomass combustion residues, and tyre fibres into cement-bonded composites : Properties of composites and life cycle analysis
- 2021
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Ingår i: Construction and Building Materials. - : Elsevier Ltd. - 0950-0618 .- 1879-0526. ; 297
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the properties and sustainability of cement-bonded composites containing industrial residues such as wood chips, tyre fibres and biomass combustion residues, i.e. bottom ash (BA) and fly ash (FA). The effect of cement-to-raw material (wood/tyre fibre) ratio (C/RM) and the aggregate content (BA and FA) on thermal and mechanical properties of the composites were investigated. Scanning electron microscopy (SEM) and life cycle analysis (LCA) were also conducted. The results revealed that as the aggregate content increased in wood composites, the mechanical properties also increased. The mean thermal conductivity and volumetric heat capacity of tyre composite samples were 0.37 W/mK and 1.2 MJ/m3K respectively, while the respective values for wood composite samples were 0.29 W/mK and 0.81 MJ/m3K. SEM analysis showed adequate bonding between wood/tyre fibres and cement matrix. LCA revealed that the materials share of the total primary energy use was about 60% for all analysed composites. © 2021 The Author(s)
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| 7. |
- Axelsson, Jakob, et al.
(författare)
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Characteristics of software ecosystems for Federated Embedded Systems : A case study
- 2014
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Ingår i: Information and Software Technology. - : Elsevier BV. - 0950-5849 .- 1873-6025. ; 56:11, s. 1457-1475
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Tidskriftsartikel (refereegranskat)abstract
- Context Traditionally, Embedded Systems (ES) are tightly linked to physical products, and closed both for communication to the surrounding world and to additions or modifications by third parties. New technical solutions are however emerging that allow addition of plug-in software, as well as external communication for both software installation and data exchange. These mechanisms in combination will allow for the construction of Federated Embedded Systems (FES). Expected benefits include the possibility of third-party actors developing add-on functionality; a shorter time to market for new functions; and the ability to upgrade existing products in the field. This will however require not only new technical solutions, but also a transformation of the software ecosystems for ES. Objective This paper aims at providing an initial characterization of the mechanisms that need to be present to make a FES ecosystem successful. This includes identification of the actors, the possible business models, the effects on product development processes, methods and tools, as well as on the product architecture. Method The research was carried out as an explorative case study based on interviews with 15 senior staff members at 9 companies related to ES that represent different roles in a future ecosystem for FES. The interview data was analyzed and the findings were mapped according to the Business Model Canvas (BMC). Results The findings from the study describe the main characteristics of a FES ecosystem, and identify the challenges for future research and practice. Conclusions The case study indicates that new actors exist in the FES ecosystem compared to a traditional supply chain, and that their roles and relations are redefined. The business models include new revenue streams and services, but also create the need for trade-offs between, e.g., openness and dependability in the architecture, as well as new ways of working. © 2014 The Authors. Published by Elsevier B.V.
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| 8. |
- Bengtsson, Charlotte, et al.
(författare)
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Conformity assessment for machine graded timber by using output control
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the Nordic countries machine strength grading of structural timber is becoming increasingly important. A new standard, EN 14081, which allows CE-marking of strength graded structural timber was recently accepted. This standard allows both machine control and output control as methods for controlling the graded timber. Machine control is most commonly used in Europe. The project reported here deals with output control. This method is commonly used in for example USA. Theoretical studies carried out within this project show that applying output control gives higher yield, especially in high strength classes. A document describing the implementation of the output control procedure is written and given in Appendix 1 of this report.
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| 9. |
- Blomqvist, Lars, 1962-, et al.
(författare)
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Distortion in laminated veneer products exposed to relative-humidity variations : Experimental studies and finite-element modelling
- 2019
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Ingår i: BioResources. - Raleigh, NC : North Carolina State Univ Dept Wood & Paper Sci. - 1930-2126. ; 14:2, s. 3768-3779
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Tidskriftsartikel (refereegranskat)abstract
- A shortcoming of the laminated bending process is that the product may become distorted after moulding. This study focused on the influence of fibre orientation deviation for individual veneers on the distortion of a moulded shell. The distortion of 90 cross-laminated shells of the same geometrical shape, consisting of seven peeled birch veneers, were studied under relative humidity variation. All the veneers were straight-grained in the longitudinal-tangential plane, but to simulate a deviation in fibre orientation, some of the individual veneers were oriented at an angle of 7° relative to the main orientation of the other veneers in the laminate. A finite element model (FEM) was applied to study the possibility of predicting the results of a practical experiment. The study confirms the well-known fact that deviation in fibre orientation influences shape stability. The results also show how the placement of the abnormal veneer influences the degree of distortion. From this basic knowledge, some improvements in the industrial production were suggested. However, the FE model significantly underestimated the results, according to the empirical experiment, and it did not show full coherence. The survey shows the complexity of modelling the behaviour of laminated veneer products under changing climate conditions and that there is a great need to improve the material and process data to achieve accurate simulations. Examples of such parameters that may lead to distortion are density, annual ring orientation in the cross section of the veneer, the orientation of the loose and tight sides of the veneer, and parameters related to the design of the moulding tool.
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| 10. |
- Blomqvist, Lars, 1962-, et al.
(författare)
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Stress distribution in veneers under lamination and simultaneously bending : an experimental and numerical investigation
- 2023
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis Group. - 1748-0272 .- 1748-0280. ; 18:3, s. 995-1002
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Tidskriftsartikel (refereegranskat)abstract
- Laminated veneer products (LVPs) are veneers glued together into a predetermined shape. Experimental and numerical investigations were performed under lamination and simultaneously bending of veneer laminate to study the stress distribution in the laminate. Laminates of different thicknesses were made of peeled veneers of European beech. The veneers were coated with adhesive, inserted in a mould which had the shape of a semicircle, and finally pressed at 20 degrees C to a laminate. Two Teflon-polymer films including sensors for measurement of the contact pressure were placed on both sides of the laminate to measure the local contact pressure (contact stress) between the laminate and the mould. At the beginning of the bending process, the contact stresses were locally distributed over the laminate in a similar pattern as in a three-point bending; after the laminate was further bent, the stress distribution rearranged to be as in four-point bending. In the end of the moulding, the local contact stresses increased over the entire laminate and reached a 'peak-value' over bent area in the middle part of the mould. A finite-element model was created to study the bending process. Regarding the overall development of the contact stress variations, the experimental and the numerical results agreed.
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