| 1. |
- Adiels, Emil, 1989, et al.
(författare)
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The design , fabrication and assembly of an asymptotic timber gridshell
- 2019
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Ingår i: IASS Symposium 2019 - 60th Anniversary Symposium of the International Association for Shell and Spatial Structures; Structural Membranes 2019 - 9th International Conference on Textile Composites and Inflatable Structures, FORM and FORCE. - 9788412110104 ; , s. 736-743
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Konferensbidrag (refereegranskat)abstract
- This paper describes and discuss the design, fabrication and assembly of an asymptotic gridshell built of plywood laths. The overall question concerns how geometry, structural action, and ecient production can interplay and inform spatial design. The environment is a two-day workshop where architects, engineers and researchers with specialization in structural and digital design cooperate with undergraduate students in a compulsory parametric design and digital fabrication course. The gridshell shape is based on an Enneper surface of threefold rotational symmetry with a boundary baseplate inscribed within a circle of 4.5 m in radius. Utilizing the concept of asymptotic curves, which are surface curves whose osculating plane coincides with the tangent plane of the surface, the structure was built using planar straight laths of plywood made using manually operated drills and saws.
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| 2. |
- Adiels, Emil, 1989, et al.
(författare)
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The use of virtual work for the formfinding of fabric, shell and gridshell structures
- 2018
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Ingår i: Proceedings of the Advances in Architectural Geometry conference 2018. - 9783903015135 ; , s. 286-315
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Konferensbidrag (refereegranskat)abstract
- The use of the virtual work theorem enables one to derive the equations of static equilibrium of fabric, shell and gridshell structures from the compatibility equations linking the rate of deformation of a surface to variations in its velocity. If the structure is treated as a continuum there is no need to consider its micro-structure provided that the grid is fine compared to the overall geometry. Thus we can include fabrics, ribbed shells, corrugated shells and gridshells with a fine grid, such as the Mannheim Multihalle. The equilibrium equations are almost identical to those obtained by assuming that a shell is thin and of uniform thickness, but are more general in their application. Our formulation introduces the concept of geodesic bending moments which are relevant to gridshell structures with continuous laths. The virtual work theorem is more general than the energy theorems, which it in- cludes as a special case. Hence it can be applied to surfaces which admit some form of potential, including minimal surfaces and hanging fabrics. We can then use the calculus of variations for the minimization of a surface integral to define the form of a structure. Many existing formfinding techniques can be rewritten in this way, but we concen- trate on surfaces which minimize the surface integral of the mean curvature subject to a constraint on the enclosed volume, producing a surface of constant Gaussian curvature. This naturally leads to the more general study of conjugate stress and curvature directions, and hence to quadrilateral mesh gridshells with flat cladding panels and no bending moments in the structural members under own weight.
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| 3. |
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| 4. |
- Alégroth, Emil, 1984, et al.
(författare)
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JAutomate: A tool for system- and acceptance-test automation
- 2013
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Ingår i: Proceedings - IEEE 6th International Conference on Software Testing, Verification and Validation, ICST 2013. - : IEEE. - 9780769549682 ; , s. 439-446
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Konferensbidrag (refereegranskat)abstract
- System- and acceptance-testing are primarily performed with manual practices in current software industry. However, these practices have several issues, e.g. they are tedious, error prone and time consuming with costs up towards 40 percent of the total development cost. Automated test techniques have been proposed as a solution to mitigate these issues, but they generally approach testing from a lower level of system abstraction, leaving a gap for a flexible, high system-level test automation technique/tool. In this paper we present JAutomate, a Visual GUI Testing (VGT) tool that fills this gap by combining image recognition with record and replay functionality for high system-level test automation performed through the system under test's graphical user interface. We present the tool, its benefits compared to other similar techniques and manual testing. In addition, we compare JAutomate with two other VGT tools based on their static properties. Finally, we present the results from a survey with industrial practitioners that identifies testrelated problems that industry is currently facing and discuss how JAutomate can solve or mitigate these problems. © 2013 IEEE.
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| 5. |
- Alégroth, Emil, 1984-, et al.
(författare)
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Practitioners' best practices to Adopt, Use or Abandon Model-based Testing with Graphical models for Software-intensive Systems
- 2022
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Ingår i: Empirical Software Engineering. - : SPRINGER. - 1382-3256 .- 1573-7616. ; 27:5
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Tidskriftsartikel (refereegranskat)abstract
- Model-based testing (MBT) has been extensively researched for software-intensive systems but, despite the academic interest, adoption of the technique in industry has been sparse. This phenomenon has been observed by our industrial partners for MBT with graphical models. They perceive one cause to be a lack of evidence-based MBT guidelines that, in addition to technical guidelines, also take non-technical aspects into account. This hypothesis is supported by a lack of such guidelines in the literature. Objective: The objective of this study is to elicit, and synthesize, MBT experts' best practices for MBT with graphical models. The results aim to give guidance to practitioners and aspire to give researchers new insights to inspire future research. Method: An interview survey is conducted using deep, semi-structured, interviews with an international sample of 17 MBT experts, in different roles, from software industry. Interview results are synthesised through semantic equivalence analysis and verified by MBT experts from industrial practice. Results: 13 synthesised conclusions are drawn from which 23 best-practice guidelines are derived for the adoption, use and abandonment of the technique. In addition, observations and expert insights are discussed that help explain the lack of wide-spread adoption of MBT with graphical models in industrial practice. Conclusions: Several technical aspects of MBT are covered by the results as well as conclusions that cover process- and organizational factors. These factors relate to the mindset, knowledge, organization, mandate and resources that enable the technique to be used effectively within an organization. The guidelines presented in this work complement existing knowledge and, as a primary objective, provide guidance for industrial practitioners to better succeed with MBT with graphical models.
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| 6. |
- Alégroth, Emil, 1984, et al.
(författare)
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Transitioning manual system test suites to automated testing: An industrial case study
- 2013
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Ingår i: Proceedings - IEEE 6th International Conference on Software Testing, Verification and Validation, ICST 2013. - : IEEE. - 9780769549682 ; , s. 56-65
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Konferensbidrag (refereegranskat)abstract
- Visual GUI testing (VGT) is an emerging technique that provides software companies with the capability to automate previously time-consuming, tedious, and fault prone manual system and acceptance tests. Previous work on VGT has shown that the technique is industrially applicable, but has not addressed the real-world applicability of the technique when used by practitioners on industrial grade systems. This paper presents a case study performed during an industrial project with the goal to transition from manual to automated system testing using VGT. Results of the study show that the VGT transition was successful and that VGT could be applied in the industrial context when performed by practitioners but that there were several problems that first had to be solved, e.g. testing of a distributed system, tool volatility. These problems and solutions have been presented together with qualitative, and quantitative, data about the benefits of the technique compared to manual testing, e.g. greatly improved execution speed, feasible transition and maintenance costs, improved bug finding ability. The study thereby provides valuable, and previously missing, contributions about VGT to both practitioners and researchers. © 2013 IEEE.
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| 7. |
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| 8. |
- Anderås, Emil, 1982-
(författare)
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Advanced MEMS Pressure Sensors Operating in Fluids
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today’s MEMS technology allows manufacturing of miniaturized, low power sensors that sometimes exceeds the performance of conventional sensors. The pressure sensor market today is dominated by MEMS pressure sensors.In this thesis two different pressure sensor techniques are studied. The first concerns ways to improve the sensitivity in the most commonly occurring pressure sensor, namely such based on the piezoresistive technique. Since the giant piezoresistive effect was observed in silicon nanowires, it was assumed that a similar effect could be expected in nano-thin silicon films. However, it turned out that the conductivity was extremely sensitive to substrate bias and could therefore be controlled by varying the backside potential. Another important parameter was the resistivity time drift. Long time measurements showed a drastic variation in the resistance. Not even after several hours of measurement was steady state reached. The drift is explained by hole injection into the buried oxide as well as existence of mobile charges. The piezoresistive effect was studied and shown to be of the same magnitude as in bulk silicon. Later research has shown the existence of such an effect where the film thickness has to be less than around 20 nm. The second area that has been studied is the pressure sensitivity of in acoustic resonators. Aluminium nitride thin film plate acoustic resonators (FPAR) operating at the lowest-order symmetric (S0), the first-order asymmetric (A1) as well as the first-order symmetric (S1) Lamb modes have been theoretically and experimentally studied in a comparative manner. The S0 Lamb mode is identified as the most pressure sensitive FPAR mode. The theoretical predictions were found to be in good agreement with the experiments. Additionally, the Lamb modes have been tested for their sensitivities to mass loading and their ability to operate in liquids, where the S0 mode showed good results.Finally, the pressure sensitivity in aluminium nitride thin film bulk wave resonators employing c- and tilted c-axis texture has been studied. The c-axis tilted FBAR demonstrates a substantially higher pressure sensitivity compared to its c-axis oriented counterpart.
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| 9. |
- Anderås, Emil, et al.
(författare)
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Drift in thin film SOI piezoresistors
- 2010
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Ingår i: Proc. of EUROSOI Workshop, 2010 Jan 25-27, Grenoble, France. ; , s. 71-72
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Konferensbidrag (refereegranskat)
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| 10. |
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