| 1. |
- Azeez, Ahmed, 1991-
(författare)
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High-Temperature Durability Prediction of Ferritic-Martensitic Steel
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Materials used for high-temperature steam turbine sections are generally subjected to harsh environments with temperatures up to 625 °C. The superior creep resistance of 9–12 % Cr ferritic-martensitic steels makes them desirable for those critical steam turbine components. Additionally, the demand for fast and frequent steam turbine start-ups, i.e. flexible operations, causes accelerated fatigue damage in critical locations, such as grooves and notches, at the high-temperature inner steam turbine casing. A durability assessment is necessary to understand the material behaviour under such high temperatures and repeated loading, and it is essential for life prediction. An accurate and less conservative fatigue life prediction approach is achieved by going past the crack initiation stage and allowing controlled growth of cracks within safe limits. Besides, beneficial load-temperature history effects, i.e. warm pre-stressing, must be utilised to enhance the fracture resistance to cracks. This dissertation presents the high-temperature durability assessment of FB2 steel, a 9-12 % Cr ferritic-martensitic steam turbine steel.Initially, isothermal low-cycle fatigue testing was performed on FB2 steel samples. A fatigue life model based on finite element strain range partitioning was utilised to predict fatigue life within the crack initiation phase. Two fatigue damage regimes were identified, i.e. plastic- and creep-dominated damage, and the transition between them depended on temperature and applied total strain. Cyclic deformation and stress relaxation behaviour were investigated to produce an elastic-plastic and creep material model that predicts the initial and mid-life cyclic behaviour of the FB2 steel.Furthermore, the thermomechanical fatigue crack growth behaviour of FB2 steel was studied. Crack closure behaviour was observed and accounted for numerically and experimentally, where crack growth rate curves collapsed into a single curve. Interestingly, the collapsed crack growth curves coincided with isothermal crack growth tests performed at the minimum temperature of the thermomechanical crack growth tests. In addition, hold times and changes in the minimum temperature of the thermomechanical fatigue cycle did not influence crack closure behaviour.Finally, warm pre-stressing effects were explored for FB2 steel. A numerical prediction model was produced to predict the increase in the apparent fracture toughness. Warm pre-stressing effects can benefit the turbine life by enhancing fracture resistance and allowing longer fatigue cracks to grow within safe limits.
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| 2. |
- Gustafsson, David, 1983-
(författare)
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Constitutive and fatigue crack propagation behaviour of Inconel 718
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this licentiate thesis the work done in the TURBO POWER project Influence of high temperature hold times on the fatigue life of nickel-based superalloys will be presented. The overall objective of this project is to develop and evaluate tools for designing against fatigue in gas turbine applications, with special focus on the nickel-based superalloy Inconel 718. Firstly, the constitutive behaviour of the material has been been studied, where focus has been placed on trying to describe the mean stress relaxation and initial softening of the material under intermediate temperatures. Secondly, the fatigue crack propagation behaviour under high temperature hold times has been studied. Focus has here been placed on investigating the main fatigue crack propagation phenomena with the aim of setting up a basis for fatigue crack propagation modelling.This thesis is divided into two parts. The first part describes the general framework, including basic constitutive and fatigue crack propagation behaviour as well as a theoretical background for the constitutive modelling of mean stress relaxation. This framework is then used in the second part, which consists of the four included papers.
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| 3. |
- Andersén, Jimmie, 1981-
(författare)
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Ett politiskt bygge : - översiktsplaneringens innehållsmässiga utveckling
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Debate often describes the evolution of spatial planning as a process of neo-liberalisation. However, this evolution has not been studied from the perspective of planning in general in Sweden. Whether comprehensive planning is also undergoing neo-liberalisation is considered here based on these overarching research questions: - To what extent has spatial planning undergone neo-liberalisation?- How can the evolution of comprehensive planning be understood as a neo-liberalisation process?Answering these questions requires an understanding of the content characterising this planning, and of what a neo-liberalisation process entails. To achieve such an understanding, this dissertation examines how planning in general can be understood as both a political control system and a market-based land use regime.The discourse of comprehensive planning was studied by analysing 17 comprehensive plans adopted in five municipalities over the 1989–2014 period.Generally, these plans follow a few main evolutionary paths. Municipal comprehensive planning has transitioned from being instrumental, encountering few problems, to becoming increasingly abstract and all-encompassing. Comprehensive planning increasingly concerns how growth is to be achieved locally. This change is occurring in both form and content. Change in form refers to the fact that comprehensive planning has been encompassing more and more subject areas over time, whereas change in content refers to the increasingly market-based content of such planning.The research question regarding the extent to which spatial planning is undergoing neo-liberalisation is answered by the obvious trend towards neo-liberalisation. This trend is not pervasive, as countervailing tendencies are also present. Spatial planning is thus becoming internally contradictory, with earlier values persisting, albeit often in interaction with new ones.The question of how comprehensive planning can be understood as a neo-liberalisation process has a three-part answer:- As content in comprehensive plans, neo-liberalisation can be understood as a focus on market rationality. - As form in comprehensive plans, neo-liberalisation can be understood as policy production with content that assumes an ever more neo-liberal orientation. Comprehensive planning during the studied period has come to include more and more municipal areas of activity.- From a neo-liberal perspective, neo-liberalisation is understood as economic utility maximisation.Planning is becoming increasingly neo-liberalised, but not neo-liberal. That this has occurred as a result of increasingly comprehensive policy formulations is somewhat surprising. We are faced with the politicisation of planning in general, which is increasingly informed by market-based policy. This trend represents a comprehensive policy shift towards more neo-liberal planning content, accompanied by more policies. More principles are appearing, addressing how planning and development are to proceed compared with the content of pre-existing plans. The neo-liberalisation process is thus occurring via means that are contradictory from a neo-liberal perspective.
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| 4. |
- Magnusson, Dick
(författare)
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District Heating in a Liberalized Energy Market: A New Order? : Planning and Development in the Stockholm Region, 1978-2012
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation analyses how district heating systems in the Stockholm region have evolved and developed during the period 1978-2012. The thesis comprises four papers analyzing how district heating has been handled in municipal and regional planning. The examination explores how actors have worked together to create regional, interconnected district heating systems with economic, technological and environmental benefits. An investigation is undertaken on the effects of liberalization (and the subsequent commercialization of the district heating market) on the planning and cooperation of these systems. The impact on the present and future district heating market is also discussed.The dissertation shows that energy companies cooperated on a regional level to create interconnected regional systems. Through openness, the capacity to make high-level decisions and municipal legitimacy, the regional strategies could be implemented at the municipal level. This can be considered a form of regional planning from below that developed through the initiative of the municipalities. The regional energy planning authority Stoseb could therefore succeed where other regional planning authorities in the Stockholm region have previous failed, to gather and unite the municipalities into a regional force.This cooperation changed around the time of the liberalization of the energy market in 1996, which led to sales of several municipal energy companies and a subsequent concentration of ownership in the region. The organizational distance between energy companies and municipalities has increased and affected the communication between them. Regional cooperation could not be maintained and this has meant that opportunities and tools to implement energy strategies today are weaker than earlier. This is a case of ‘regional splintering’. The liberalization of the energy market thus had a major impact on the district heating sector.
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| 5. |
- Palmert, Frans, 1986-
(författare)
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Crack growth in single crystal nickel base superalloys under isothermal and thermomechanical fatigue
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work concerns the fatigue crack growth behaviour of nickel base single crystal superalloys. The main industrial application of this class of materials is in gas turbine blades, where the ability to withstand severe mechanical loading in combination with high temperatures is required. In order to ensure the structural integrity of gas turbine blades, knowledge of the fatigue crack growth behaviour under service-like conditions is of utmost importance. The aim of the present work is both to improve the understanding of the crack growth behaviour of single crystal superalloys and also to improve the testing and evaluation methodology for crack propagation under thermomechanical fatigue loading conditions. Single crystal superalloys have anisotropic mechanical properties and are prone to localization of inelastic deformation along the close-packed planes of the crystal lattice. Under some conditions, crystallographic crack growth occurs along these planes and this is a complicating factor throughout the whole chain of crack propagation life simulation; from material data generation to component calculation. Fatigue crack growth testing has been performed, both using conventional isothermal testing methods and also using thermomechanical fatigue crack growth testing. Experimental observations regarding crystallographic crack growth have been made and its dependence on crystal orientation and testing temperature has been investigated. Quantitative crack growth data are however only presented for the case of Mode I crack growth under isothermal as well as thermomechanical fatigue conditions. Microstructural investigations have been undertaken to investigate the deformation mechanisms governing the crack growth behaviour. A compliance based method for the evaluation of crack opening force under thermomechanical fatigue conditions was developed, in order to enable a detailed analysis of the test data. The crack opening force evaluation proved to be of key importance in the understanding of the crack driving force under different testing conditions.
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| 6. |
- Albrecht, Frederike, et al.
(författare)
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Patterns of Parliamentary Opposition : Empirical Evidence from the Deliberations in the German Bundestag’s Committee on European Union Affairs
- 2021
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Ingår i: Parliamentary Affairs. - : Oxford University Press. - 0031-2290 .- 1460-2482. ; 74:1, s. 230-251
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Tidskriftsartikel (refereegranskat)abstract
- This article examines patterns of oppositional behaviour in the German Bundestag’s Committee on European Union Affairs (EAC) for two separate legislative periods (2005–2009 and 2009–2013). The study makes two contributions to previous research. It, first, shed some much-needed empirical light on political opposition in the Bundestag by examining how much and what kind of opposition exists in the German EAC. Secondly, the article examines the differences in oppositional behaviour of the Members of Parliament between the two legislative periods following an institutional reform in 2009 that afforded the Bundestag with increased opportunity structures in Europen Union affairs.
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| 7. |
- Ewalds, Nina, 1958-
(författare)
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Internationell beskattning av pensionsförsäkringar : – det svenska skattesystemet i gränsöverskridande situationer
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The question at hand throughout this thesis is how the Swedish system for taxation of pension insurances – in both individual and occupational private pension schemes – interacts with other tax systems in an international context. This question includes several aspects. What are the outcomes when the Swedish system interacts with another Member State’s tax system in a cross-border situation? To what degree does the Swedish taxation of pension insurances live up to the underlying objectives of the system? Does the Swedish system constitute a restriction to free movement in the internal market for pension insurances? In order to be able to answer these and similar questions, a number of concrete situations that arise when the Swedish tax system meets a differently designed tax system of another Member State – Finland – are analysed. The Swedish taxation of pension insurances differs from that of a number of Member States as the Swedish system not only subjects the pension capital to a yield tax but also taxes the benefits upon disbursement to the beneficiary. In most other western European Member States – among them Finland – only the disbursed benefits are subjected to tax.The results of the situation into the tax consequences in cross-border situations show that the Swedish system for taxation of pension insurances is not functioning in an international context. Sweden only manages to maintain the reciprocity within its tax system in a few of the analysed situations. The taxpayers are subjected to double taxation – sometimes even triple taxation – which is not eliminated by double taxation agreements or by regulations on credit-of-tax in national law. In the internal market for pension insurances, free movement is restricted and from a strictly national perspective, the underlying objectives of the Swedish system are not achieved.
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| 8. |
- Karlsson, Christer, Professor, 1965-, et al.
(författare)
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Comparing oppositional behaviour in European Union affairs : empirical evidence from six member states
- 2022
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Ingår i: West European Politics. - : Taylor & Francis. - 0140-2382 .- 1743-9655. ; 45:2, s. 286-310
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Tidskriftsartikel (refereegranskat)abstract
- This article offers a comprehensive comparison of oppositional behaviour in European Union (EU) affairs in six countries: Austria, Denmark, Germany, Ireland, Sweden and the United Kingdom. By drawing on a unique data set of hand-coded statements made by Members of Parliament during European Affairs Committee (EAC) meetings it provides new knowledge on political opposition. The data uncover that there is more opposition expressed in EU affairs than has been assumed by previous research. The results also reveal that there exists considerable cross-national variation in oppositional behaviour during EAC deliberations in the six countries. The study finally shows that Eurosceptic parties are key drivers of opposition in EU affairs, especially when it comes to opposition directed at the EU political system.
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| 9. |
- Karlsson, Christer, Professor, 1965-, et al.
(författare)
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Dimensions of disagreement in EU affairs : is parliamentary opposition driven by left-right or European integration contestation?
- 2024
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Ingår i: West European Politics. - 0140-2382 .- 1743-9655.
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Tidskriftsartikel (refereegranskat)abstract
- This study provides new insights regarding how the EU dimension relates to the left-right dimension in national politics. It does so by examining to what extent parties’ oppositional behaviour in EU affairs in parliament is a function of their distance to the government, other parties, the voters and party supporters on the EU dimension and the left-right dimension, respectively. The results suggest that oppositional behaviour is determined by two parallel dynamics: When expressing opposition, political parties are receptive both to the positions of the government and other parties on the EU dimension, and to the positions of voters and supporters on the left-right dimension. Our results thus indicate that the politicization of EU affairs in national parliaments primarily is an elite phenomenon. In their relation to the voters and supporters, parties still primarily navigate along the traditional left-right dimension.
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| 10. |
- Karlsson, Christer, Professor, 1965-, et al.
(författare)
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Do Members of Parliament Express More Opposition in the Plenary than in the Committee? : Comparing Frontstage and Backstage Behaviour in Five National Parliaments
- 2024
-
Ingår i: Parliamentary Affairs. - : Oxford University Press. - 0031-2290 .- 1460-2482. ; 77:1, s. 173-195
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Tidskriftsartikel (refereegranskat)abstract
- This study attempts to break new ground by systematically comparing oppositional behaviour of Members of Parliament (MPs) in the two key arenas found in parliament: the plenary and the committee. Do MPs express more opposition frontstage in the plenary than backstage in the committee when discussing European affairs? The article sheds new light on political opposition in parliament by using a dataset of hand-coded statements made by MPs during plenary debates and European Affairs committee deliberations in five national parliaments. The results lend strong support to the main hypothesis that MPs express more opposition during plenary debates than committee deliberations.
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| 11. |
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| 12. |
- Karlsson, Christer, Professor, 1965-, et al.
(författare)
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Hur mycket opposition finns det i svensk EU-politik?
- 2019
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Ingår i: EU i riksdagen. - Stockholm : Svenska institutet för europapolitiska studier (Sieps). - 9789186107826 ; , s. 37-60
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Karlsson, Christer, Professor, 1965-, et al.
(författare)
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Is Oppositional Behaviour in European Union Affairs Gendered? Evidence from Plenary Debates and Committee Deliberations in Four Legislatures
- 2024
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Ingår i: Journal of Common Market Studies. - : John Wiley & Sons. - 0021-9886 .- 1468-5965. ; 62:2, s. 412-429
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Tidskriftsartikel (refereegranskat)abstract
- Is oppositional behaviour in legislatures gendered? Despite a growing literature on gender and legislative behaviour, there is a conspicuous absence of research on differences between female and male members of parliament (MPs) when it comes to one of the key aspects of parliamentary debates: the voicing of opposition. This article connects the literature on gender and legislative behaviour with opposition scholarship. We examine the role of gender for oppositional behaviour in four legislatures with a focus on debates concerning European Union affairs. Our results show that female MPs generally are equally likely to express opposition as their male colleagues. This result, however, is conditioned by government status. Whilst there is no significant difference between the proportion of opposition expressed by female and male MPs from opposition parties, we find that male MPs representing government parties express more than twice as much opposition as their female colleagues.
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| 14. |
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| 15. |
- Persson, Thomas, 1969-, et al.
(författare)
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Drivers of parliamentary opposition in European Union politics: institutional factors or party characteristics?
- 2024
-
Ingår i: Journal of European Public Policy. - : Informa UK Limited. - 1350-1763 .- 1466-4429. ; 31:3
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Tidskriftsartikel (refereegranskat)abstract
- A vital political opposition is one of the cornerstones of democracy, yet we know surprisingly little about the conditions that shape it. In this paper, we offer a comprehensive assessment of the drivers of parliamentary opposition in European Union (EU) politics in five countries: Denmark; Germany; Ireland; Sweden; and the United Kingdom. Based on an extensive hand-coded data set of 7,520 statements made by members of parliament (MPs) during both plenary sessions and deliberations during European Affairs Committee (EAC) meetings, we examine how institutions and party characteristics shape two types of oppositional behaviour: the expression of critique and the presentation of alternatives. We find that both factors are important for understanding to what extent, and how, opposition is voiced in national parliaments. Oversight institutions’ strength and a party’s degree of Euroscepticism jointly function as significant determinants of the likelihood that MPs will express opposition in the form of critique. However, when it comes to the likelihood of offering alternatives, oversight institutions’ strength fails to explain variations in the share of alternatives, while degree of Euroscepticism remains a significant predictor.
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| 16. |
- Persson, Thomas, 1969-, et al.
(författare)
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Eurosceptic Challenger Parties and Political Opposition in European Union Politics : Part of the Problem or Part of the Solution?
- 2019
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Ingår i: Scandinavian Political Studies. - : John Wiley & Sons. - 0080-6757 .- 1467-9477. ; 42:3-4, s. 245-269
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Tidskriftsartikel (refereegranskat)abstract
- Despite extensive research on Eurosceptic challenger parties, our knowledge of their influence on political opposition has so far been sparse. In this article we make an in-depth assessment of parliamentary EU opposition, based on 4,264 statements made by national parliamentarians in the European Affairs Committees (EACs) of Denmark and Sweden. Our analysis shows that the presence of Eurosceptic challenger parties in the national parliamentary arena impacts patterns and practices of EU opposition significantly. A greater presence of ‘hard’ Eurosceptic parties in parliament is associated with more opposition in EU politics. These parties deliver a vast majority of the polity-oriented opposition towards the EU and present more policy alter- natives than mainstream parties. The findings presented have implications for our understand- ing of national parliamentary EU opposition as well as for the assessment of the impact of Eurosceptic challenger parties on the process of European integration.
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| 17. |
- Persson, Thomas, 1969-, et al.
(författare)
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The influence of Eurosceptic challenger parties on mainstream party behaviour : Is oppositional behaviour contagious?
- 2023
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Ingår i: Party Politics. - : Sage Publications. - 1354-0688 .- 1460-3683. ; 29:1, s. 100-111
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has looked at how Eurosceptic challenger parties can cause mainstream parties to change their policy positions and bring about adjustments to their programmes. We explore whether this contagion effect extends to the parliamentary behaviour of mainstream parties in European Union (EU) affairs. The empirical analysis is based on a large-scale study of 6215 statements made by national parliamentarians in the European Affairs Committee of Sweden between 1995 and 2016. A dynamic panel analysis of the data shows that the oppositional behaviour of Eurosceptic challenger parties has a significant impact on the opposition statements made in EU affairs by mainstream parties. These findings have important implications for the general understanding of factors that drive national EU opposition.
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| 18. |
- Persson, Ulf, 1950-, et al.
(författare)
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Letter to the Editor : [About Institute Mittag-Leffler]
- 2021
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Ingår i: Notices of the American Mathematical Society. - Provicence, RI : American Mathematical Society (AMS). - 0002-9920 .- 1088-9477. ; 68:3, s. 319-320
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 19. |
- Schwartz, Christofer, et al.
(författare)
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On-board Satellite Data Processing to Achieve Smart Information Collection
- 2022
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 9781510651524
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Konferensbidrag (refereegranskat)abstract
- Nowadays, it is a reality to launch, operate, and utilize small satellites at an affordable cost. However, bandwidth constraint is still an important challenge. For instance, multispectral and hyperspectral sensors generate a significant amount of data subjected to communication channel impairments, which is addressed mainly by source and channel coding aiming at an effective transmission. This paper targets a significant further bandwidth reduction by proposing an on-the-fly analysis technique on the satellite to decide which information is effectively useful for specific target applications, before coding and transmitting. The challenge would be detecting clouds and vessels having the measurements of red-band, green-band, blue-band, and near infrared band, aiming at sufficient probability of detection, avoiding false alarms. Furthermore, the embedded platform constraints must be satisfied. Experiments for typical scenarios of summer and winter days in Stockholm, Sweden, are conducted using data from the Mimir’s Well, the Saab AI-based data fusion system. Results show that non-relevant content can be identified and discarded, pointing out that for the cloudy scenarios evaluated, up to 73.1% percent of image content can be suppressed without compromising the useful information into the image. For the water regions in the scenarios containing vessels, results indicate that a stringent amount of data can be discarded (up to 98.5%) when transmitting only the regions of interest (ROI).
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| 20. |
- Schwartz, Christofer, et al.
(författare)
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Satellite Image Compression Guided by Regions of Interest
- 2023
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 23:2
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Tidskriftsartikel (refereegranskat)abstract
- Small satellites empower different applications for an affordable price. By dealing with a limited capacity for using instruments with high power consumption or high data-rate requirements, small satellite missions usually focus on specific monitoring and observation tasks. Considering that multispectral and hyperspectral sensors generate a significant amount of data subjected to communication channel impairments, bandwidth constraint is an important challenge in data transmission. That issue is addressed mainly by source and channel coding techniques aiming at an effective transmission. This paper targets a significant further bandwidth reduction by proposing an on-the-fly analysis on the satellite to decide which information is effectively useful before coding and transmitting. The images are tiled and classified using a set of detection algorithms after defining the least relevant content for general remote sensing applications. The methodology makes use of the red-band, green-band, blue-band, and near-infrared-band measurements to perform the classification of the content by managing a cloud detection algorithm, a change detection algorithm, and a vessel detection algorithm. Experiments for a set of typical scenarios of summer and winter days in Stockholm, Sweden, were conducted, and the results show that non-important content can be identified and discarded without compromising the predefined useful information for water and dry-land regions. For the evaluated images, only 22.3% of the information would need to be transmitted to the ground station to ensure the acquisition of all the important content, which illustrates the merits of the proposed method. Furthermore, the embedded platform’s constraints regarding processing time were analyzed by running the detection algorithms on Unibap’s iX10-100 space cloud platform.
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| 21. |
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