| 1. |
- Kerren, Andreas, 1971-, et al.
(författare)
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Multi-Scale Trend Visualization of Long-Term Temperature Data Sets
- 2014
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Ingår i: Proceedings of SIGRAD 2014, Visual Computing, June 12-13, 2014, Göteborg, Sweden. - : Linköping University Electronic Press. - 9789175192123 ; , s. 91-94
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Konferensbidrag (refereegranskat)abstract
- The analysis and presentation of climate observations is a traditional application of various visualization approaches. The available data sets are usually huge and were typically collected over a long period of time. In this paper, we focus on the visualization of a specific aspect of climate data: our visualization tool was primarily developed for providing an overview of temperature measurements for one location over decades or even centuries. In order to support an efficient overview and visual representation of the data, it is based on a region-oriented metaphor that includes various granularity levels and aggregation features.
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| 2. |
- Ibragimov, Nail H., et al.
(författare)
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Utilization of photon orbital angular momentum in the low-frequency radio domain
- 2007
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 99:8
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Tidskriftsartikel (refereegranskat)abstract
- We show numerically that vector antenna arrays can generate radio beams that exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (1 GHz), digital techniques can be used to coherently measure the instantaneous, local field vectors and to manipulate them in software. This enables new types of experiments that go beyond what is possible in optics. It allows information-rich radio astronomy and paves the way for novel wireless communication concepts.
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| 3. |
- Ståhle, Per, et al.
(författare)
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Interface instabilities of growing hydrides
- 2016
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Ingår i: Procedia Structural Integrity. - : Elsevier BV. - 2452-3216. ; 2, s. 589-596
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Tidskriftsartikel (refereegranskat)abstract
- Formation of metal hydrides is a serious complication that occur when hydride forming metals such as zirconium, niobium, vanadium and magnesium are exposed to long term hydrogen environment. The main concern is that the hydride, as being a brittle material, has very poor fracture mechanical properties. Formation of hydride is associated with transportation of hydrogen along the gradients of increasing hydrostatic stress, which leads to crack tips and other stress concentrators, where it forms the hydride. In the present study the thermodynamics of the evolving hydrides is studied. The process is driven by the release of free strain, chemical, and gradient energies. A phase field model is used to capture the driving forces that the release of the free energy causes. The study gives the conditions that lead to hydride advancement versus retreat and under which conditions the metal-hydride interface becomes unstable and develops a waviness. The spatial frequency spectrum leading to instability is found to depend on the ratio of the elastic strain energy density and parameters related to the interface energy.
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| 4. |
- Olsson, Pär, et al.
(författare)
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Ab initio and classical atomistic modelling of structure and defects in crystalline orthorhombic polyethylene : Twin boundaries, slip interfaces, and nature of barriers
- 2017
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Ingår i: Polymer. - : Elsevier Ltd. - 0032-3861 .- 1873-2291. ; 121, s. 234-246
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Tidskriftsartikel (refereegranskat)abstract
- We study the stability of twin boundaries and slip in crystalline orthorhombic polyethylene by means of density functional theory (DFT), using a nonempirical, truly nonlocal density function, and by means of classical molecular dynamics (MD). The results show that, in accordance with experimental observations, there is a clear preference to chain slip over transverse slip for all considered slip planes. The activation energy for pure chain slip lies in the range 10–20 mJ/m2 while that for transverse slip corresponds to 40–280 mJ/m2. For the (11¯0)-slip plane the energy landscape is non-convex with multiple potential energy minima, indicating the presence of stable stacking faults. This suggests that dissociation of perfect dislocations into partials may occur. For the two low-energy twin boundaries considered in this work, {110} and {310}, we find that the former is more stable than the latter, with ground state energies corresponding to 8.9 and 28 mJ/m2, respectively. We have also evaluated how well the empirical MD simulations with the all-atom optimized potential for liquid MD simulations (OPLS-AA) and the coarse-grained united atom (UA) potential concur with the DFT results. It is found that an all-atom potential is necessary to partially capture the γ-surface energy landscapes obtained from the DFT calculations. The OPLS-AA predicts chain slip activation energies comparable with DFT data, while the transverse slip energy thresholds are low in comparison, which is attributed to weak close ranged monomer repulsion. Finally, we find that the H-H interaction dominates the slip activation. While not explicitly represented in the UA potential, its key role is revealed by correlating the DFT energy landscape with changes in the electron distributions and by MD simulations in which components of the OPLS-AA intermolecular potential are selectively silenced. © 2017 Elsevier Ltd
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| 5. |
- Alahyari, Hiva, 1979, et al.
(författare)
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A study of value in agile software development organizations
- 2017
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Ingår i: Journal of Systems and Software. - : Elsevier BV. - 0164-1212 .- 1873-1228. ; 125, s. 271-288
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Tidskriftsartikel (refereegranskat)abstract
- The Agile manifesto focuses on the delivery of valuable software. In Lean, the principles emphasise value, where every activity that does not add value is seen as waste. Despite the strong focus on value, and that the primary critical success factor for software intensive product development lies in the value domain, no empirical study has investigated specifically what value is. This paper presents an empirical study that investigates how value is interpreted and prioritised, and how value is assured and measured. Data was collected through semi-structured interviews with 23 participants from 14 agile software development organisations. The contribution of this study is fourfold. First, it examines how value is perceived amongst agile software development organisations. Second, it compares the perceptions and priorities of the perceived values by domains and roles. Third, it includes an examination of what practices are used to achieve value in industry, and what hinders the achievement of value. Fourth, it characterises what measurements are used to assure, and evaluate value-creation activities. (C) 2016 Elsevier Inc. All rights reserved.
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| 6. |
- Berntsson Svensson, Richard, et al.
(författare)
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Prioritization of quality requirements : State of practice in eleven companies
- 2011
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Ingår i: 2011 IEEE 19th International Requirements Engineering Conference, RE 2011; Trento; 29 August 2011 through 2 September 2011. - Trento : IEEE. - 9781457709234 ; , s. 69-78, s. 69-78
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Konferensbidrag (refereegranskat)abstract
- Requirements prioritization is recognized as an important but challenging activity in software product development. For a product to be successful, it is crucial to find the right balance among competing quality requirements. Although literature offers many methods for requirements prioritization, the research on prioritization of quality requirements is limited. This study identifies how quality requirements are prioritized in practice at 11 successful companies developing software intensive systems. We found that ad-hoc prioritization and priority grouping of requirements are the dominant methods for prioritizing quality requirements. The results also show that it is common to use customer input as criteria for prioritization but absence of any criteria was also common. The results suggests that quality requirements by default have a lower priority than functional requirements, and that they only get attention in the prioritizing process if decision-makers are dedicated to invest specific time and resources on QR prioritization. The results of this study may help future research on quality requirements to focus investigations on industry-relevant issues.
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| 7. |
- Ding, Jianguo
(författare)
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Intrusion Detection, Prevention, and Response System (IDPRS) for Cyber-Physical Systems (CPSs)
- 2015
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Ingår i: Securing Cyber Physical Systems. - Boca Raton, US : Taylor & Francis Group. - 9781498700986 - 9781498700993 - 9780429091049 ; , s. 371-392
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Bokkapitel (refereegranskat)abstract
- Cyber-physical systems (CPSs) are integrated physical, engineered, andsocial systems whose operations are monitored, coordinated, controlled, and integratedby a computing and communication core. Due to the dynamic structure ofCPSs, the security measurements are often complex. Given this fact, the objectiveof this chapter is to present the intrusion detection, prevention, and response system(IDPRS) for such a dynamic environment.
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| 8. |
- Gosson, Maurice de
(författare)
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The Principles of Classical and Quantum Mechanics
- 2002
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Ingår i: Hardcover. - London-Singapore : Imperial College Press.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This book is devoted to a symplectic approach of classical and quantum mechanics
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| 9. |
- Gren, Lucas, 1984-, et al.
(författare)
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Is it possible to disregard obsolete requirements? a family of experiments in software effort estimation
- 2021
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Ingår i: Requirements Engineering. - : Springer Science and Business Media Deutschland GmbH. - 0947-3602 .- 1432-010X. ; :3, s. 459-480
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Tidskriftsartikel (refereegranskat)abstract
- Expert judgement is a common method for software effort estimations in practice today. Estimators are often shown extra obsolete requirements together with the real ones to be implemented. Only one previous study has been conducted on if such practices bias the estimations. We conducted six experiments with both students and practitioners to study, and quantify, the effects of obsolete requirements on software estimation. By conducting a family of six experiments using both students and practitioners as research subjects (N= 461), and by using a Bayesian Data Analysis approach, we investigated different aspects of this effect. We also argue for, and show an example of, how we by using a Bayesian approach can be more confident in our results and enable further studies with small sample sizes. We found that the presence of obsolete requirements triggered an overestimation in effort across all experiments. The effect, however, was smaller in a field setting compared to using students as subjects. Still, the over-estimations triggered by the obsolete requirements were systematically around twice the percentage of the included obsolete ones, but with a large 95% credible interval. The results have implications for both research and practice in that the found systematic error should be accounted for in both studies on software estimation and, maybe more importantly, in estimation practices to avoid over-estimations due to this systematic error. We partly explain this error to be stemming from the cognitive bias of anchoring-and-adjustment, i.e. the obsolete requirements anchored a much larger software. However, further studies are needed in order to accurately predict this effect. © 2021, The Author(s).
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| 10. |
- Hatamian, Majid, et al.
(författare)
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A privacy and security analysis of early-deployed COVID-19 contact tracing Android apps
- 2021
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Ingår i: Empirical Software Engineering. - : Springer Nature. - 1382-3256 .- 1573-7616. ; 26:3
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Tidskriftsartikel (refereegranskat)abstract
- As this article is being drafted, the SARS-CoV-2/COVID-19 pandemic is causing harm and disruption across the world. Many countries aimed at supporting their contact tracers with the use of digital contact tracing apps in order to manage and control the spread of the virus. Their idea is the automatic registration of meetings between smartphone owners for the quicker processing of infection chains. To date, there are many contact tracing apps that have already been launched and used in 2020. There has been a lot of speculations about the privacy and security aspects of these apps and their potential violation of data protection principles. Therefore, the developers of these apps are constantly criticized because of undermining users’ privacy, neglecting essential privacy and security requirements, and developing apps under time pressure without considering privacy- and security-by-design. In this study, we analyze the privacy and security performance of 28 contact tracing apps available on Android platform from various perspectives, including their code’s privileges, promises made in their privacy policies, and static and dynamic performances. Our methodology is based on the collection of various types of data concerning these 28 apps, namely permission requests, privacy policy texts, run-time resource accesses, and existing security vulnerabilities. Based on the analysis of these data, we quantify and assess the impact of these apps on users’ privacy. We aimed at providing a quick and systematic inspection of the earliest contact tracing apps that have been deployed on multiple continents. Our findings have revealed that the developers of these apps need to take more cautionary steps to ensure code quality and to address security and privacy vulnerabilities. They should more consciously follow legal requirements with respect to apps’ permission declarations, privacy principles, and privacy policy contents.
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