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  • Public defence: 2017-09-26 13:15 Ada Lovelace, Linköping
    Dragisic, Zlatan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Completion of Ontologies and Ontology Networks2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The World Wide Web contains large amounts of data, and in most cases this data has no explicit structure. The lack of structure makes it difficult for automated agents to understand and use such data. A step towards a more structured World Wide Web is the Semantic Web, which aims at introducing semantics to data on the World Wide Web. One of the key technologies in this endeavour are ontologies, which provide a means for modeling a domain of interest and are used for search and integration of data.

    In recent years many ontologies have been developed. To be able to use multiple ontologies it is necessary to align them, i.e., find inter-ontology relationships. However, developing and aligning ontologies is not an easy task and it is often the case that ontologies and their alignments are incorrect and incomplete. This can be a problem for semantically-enabled applications. Incorrect and incomplete ontologies and alignments directly influence the quality of the results of such applications, as wrong results can be returned and correct results can be missed. This thesis focuses on the problem of completing ontologies and ontology networks.

    The contributions of the thesis are threefold. First, we address the issue of completing the is-a structure and alignment in ontologies and ontology networks. We have formalized the problem of completing the is-a structure in ontologies as an abductive reasoning problem and developed algorithms as well as systems for dealing with the problem. With respect to the completion of alignments, we have studied system performance in the Ontology Alignment Evaluation Initiative, a yearly evaluation campaign for ontology alignment systems. We have also addressed the scalability of ontology matching, which is one of the current challenges, by developing an approach for reducing the search space when generating the alignment.Second, high quality completion requires user involvement. As users' time and effort are a limited resource we address the issue of limiting and facilitating user interaction in the completion process. We have conducted a broad study of state-of-the-art ontology alignment systems and identified different issues related to the process. We have also conducted experiments to assess the impact of user errors in the completion process.

    While the completion of ontologies and ontology networks can be done at any point in the life-cycle of ontologies and ontology networks, some of the issues can be addressed already in the development phase. The third contribution of the thesis addresses this by introducing ontology completion and ontology alignment into an existing ontology development methodology.

    List of papers
    1. Completing the is-a structure in light-weight ontologies
    Open this publication in new window or tab >>Completing the is-a structure in light-weight ontologies
    2015 (English)In: Journal of Biomedical Semantics, ISSN 2041-1480, Vol. 6, 12Article in journal (Refereed) Published
    Abstract [en]

     Background: With the increasing presence of biomedical data sources on the Internet more and more research effort is put into finding possible ways for integrating and searching such often heterogeneous sources. Ontologies are a key technology in this effort. However, developing ontologies is not an easy task and often the resulting ontologies are not complete. In addition to being problematic for the correct modelling of a domain, such incomplete ontologies, when used in semantically-enabled applications, can lead to valid conclusions being missed.

    Results: We consider the problem of repairing missing is-a relations in ontologies. We formalize the problem as a generalized TBox abduction problem. Based on this abduction framework, we present complexity results for the existence, relevance and necessity decision problems for the generalized TBox abduction problem with and without some specific preference relations for ontologies that can be represented using a member of the EL family of description logics. Further, we present algorithms for finding solutions, a system as well as experiments.

    Conclusions: Semantically-enabled applications need high quality ontologies and one key aspect is their completeness. We have introduced a framework and system that provides an environment for supporting domain experts to complete the is-a structure of ontologies. We have shown the usefulness of the approach in different experiments. For the two Anatomy ontologies from the Ontology Alignment Evaluation Initiative, we repaired 94 and 58 initial given missing is-a relations, respectively, and detected and repaired additionally, 47 and 10 missing is-a relations. In an experiment with BioTop without given missing is-a relations, we detected and repaired 40 new missing is-a relations.

    National Category
    Computer Science Bioinformatics (Computational Biology)
    Identifiers
    urn:nbn:se:liu:diva-116628 (URN)10.1186/s13326-015-0002-8 (DOI)000353197200001 ()25883780 (PubMedID)
    Funder
    Swedish e‐Science Research CenterCUGS (National Graduate School in Computer Science)
    Available from: 2015-03-29 Created: 2015-03-29 Last updated: 2017-08-21
    2. Get my pizza right: Repairing missing is-a relations in ALC ontologies
    Open this publication in new window or tab >>Get my pizza right: Repairing missing is-a relations in ALC ontologies
    2012 (English)In: Second Joint International Semantic Technology Conference, Springer Berlin/Heidelberg, 2012, 17-32 p.Chapter in book (Refereed)
    Abstract [en]

    With the increased use of ontologies in semantically-enabled applications, the issue of debugging defects in ontologies has become increasingly important. These defects can lead to wrong or incomplete results for the applications. Debugging consists of the phases of detection and repairing. In this paper we focus on the repairing phase of a particular kind of defects, i.e. the missing relations in the is-a hierarchy. Previous work has dealt with the case of taxonomies. In this work we extend the scope to deal with ALC ontologies that can be represented using acyclic terminologies. We present algorithms and discuss a system.

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2012
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 (print), 1611-3349 (online) ; 7774
    Keyword
    ontologies, ontology engineering, ontology debugging, knowledge representation
    National Category
    Computer Science
    Identifiers
    urn:nbn:se:liu:diva-91435 (URN)10.1007/978-3-642-37996-3_2 (DOI)978-3-642-37995-6 (ISBN)978-3-642-37996-3 (ISBN)
    Funder
    Swedish e‐Science Research CenterSwedish Research Council, 2010-4759CUGS (National Graduate School in Computer Science)
    Available from: 2013-04-24 Created: 2013-04-24 Last updated: 2017-08-21
    3. Reducing the search space in ontology alignment using clustering techniques and topic identification
    Open this publication in new window or tab >>Reducing the search space in ontology alignment using clustering techniques and topic identification
    2015 (English)In: Proceedings of the 8th International Conference on Knowledge Capture, New York: ACM Digital Library, 2015, 21- p.Conference paper, Published paper (Refereed)
    Abstract [en]

    One of the current challenges in ontology alignment is scalability and one technique to deal with this issue is to reduce the search space for the generation of mapping suggestions. In this paper we develop a method to prune that search space by using clustering techniques and topic identification. Further, we provide experiments showing that we are able to generate partitions that allow for high quality alignments with a highly reduced effort for computation and validation of mapping suggestions for the parts of the ontologies in the partition. Other techniques will still be needed for finding mappings that are not in the partition.

    Place, publisher, year, edition, pages
    New York: ACM Digital Library, 2015
    Keyword
    Knowledge representation, data mining, ontology alignment
    National Category
    Computer Science
    Identifiers
    urn:nbn:se:liu:diva-121838 (URN)10.1145/2815833.2816959 (DOI)978-1-4503-3849-3 (ISBN)
    Conference
    8th International Conference on Knowledge Capture
    Funder
    CUGS (National Graduate School in Computer Science)Swedish e‐Science Research CenterEU, FP7, Seventh Framework Programme, FP7-IP-608142
    Available from: 2015-10-09 Created: 2015-10-09 Last updated: 2017-08-21
    4. Experiences from the Anatomy track in the Ontology Alignment Evaluation Initiative
    Open this publication in new window or tab >>Experiences from the Anatomy track in the Ontology Alignment Evaluation Initiative
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Background: One of the longest running tracks in the Ontology Alignment Evaluation Initiative is the Anatomy track which focuses on aligning two anatomy ontologies. The Anatomy track was started in 2005. In 2005 and 2006 the task in this track was to align the Foundational Model of Anatomy and the OpenGalen Anatomy Model. Since 2007 the ontologies used in the track are the Adult Mouse Anatomy and a part of the NCI Thesaurus. Since 2015 the data in the Anatomy track is also used in the Interactive track of the Ontology Alignment Evaluation Initiative.

    Results: In this paper we focus on the Anatomy track in the years 2007-2016 and the Anatomy part of the Interactive track in 2015-2016. We describe the data set and the changes it went through during the years. Further, we give an overview of all systems that participated in the track and the techniques they have used. We discuss the performance results of the systems and summarize the general trends.

    Conclusions: About 50 systems have participated in the Anatomy track. Many different techniques were used. The most popular matching techniques are string-based strategies and structure-based techniques. Many systems also use auxiliary information. The quality of the alignment has increased for the best performing systems since the beginning of the track and more and more systems check the coherence of the proposed alignment and implement a repair strategy.Further, interacting with an oracle is beneficial.

    Keyword
    ontologies, ontology matching, OAEI, anatomy
    National Category
    Computer Science
    Identifiers
    urn:nbn:se:liu:diva-139775 (URN)
    Funder
    Swedish e‐Science Research CenterCUGS (National Graduate School in Computer Science)EU, FP7, Seventh Framework Programme, FP7-IP-608142
    Available from: 2017-08-21 Created: 2017-08-21 Last updated: 2017-08-30
    5. User validation in ontology alignment
    Open this publication in new window or tab >>User validation in ontology alignment
    Show others...
    2016 (English)In: The Semantic Web - ISWC 2016: 15th International Semantic Web Conference, Kobe, Japan, October 17–21, 2016, Proceedings, Part I / [ed] Paul Groth, Elena Simperl, Alasdair Gray, Marta Sabou, Markus Krötzsch, Freddy Lecue, Fabian Flöck and Yolanda Gil, Cham, Switzerland: Springer Publishing Company, 2016, 200-217 p.Chapter in book (Refereed)
    Abstract [en]

    User validation is one of the challenges facing the ontology alignment community, as there are limits to the quality of automated alignment algorithms. In this paper we present a broad study on user validation of ontology alignments that encompasses three distinct but interrelated aspects: the profile of the user, the services of the alignment system, and its user interface. We discuss key issues pertaining to the alignment validation process under each of these aspects, and provide an overview of how current systems address them. Finally, we use experiments from the Interactive Matching track of the Ontology Alignment Evaluation Initiative (OAEI) 2015 to assess the impact of errors in alignment validation, and how systems cope with them as function of their services.

    Place, publisher, year, edition, pages
    Cham, Switzerland: Springer Publishing Company, 2016
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 9981
    Keyword
    knowledge representation, user interfaces, ontology engineering, ontology alignment
    National Category
    Computer Science
    Identifiers
    urn:nbn:se:liu:diva-131806 (URN)10.1007/978-3-319-46523-4_13 (DOI)000389086500013 ()9783319465227 (ISBN)9783319465234 (ISBN)
    Funder
    Swedish e‐Science Research CenterCUGS (National Graduate School in Computer Science)EU, FP7, Seventh Framework Programme, FP7-IP-608142
    Available from: 2016-10-07 Created: 2016-10-07 Last updated: 2017-08-25Bibliographically approved
    6. Integrating Ontology Debugging and Matching into the eXtreme Design Methodology
    Open this publication in new window or tab >>Integrating Ontology Debugging and Matching into the eXtreme Design Methodology
    2015 (English)In: Proceedings of the 6th Workshop on Ontology and Semantic Web Patterns (WOP 2015) / [ed] Eva Blomqvist; Pascal Hitzler; Adila Krisnadhi; Tom Narock; Monika Solanki, Rheinisch-Westfaelische Technische Hochschule Aachen University , 2015Conference paper, Published paper (Refereed)
    Abstract [en]

    Ontology design patterns (ODPs) and related ontology development methodologies were designed as ways of sharing and reusing best practices in ontology engineering. However, while the use of these reduces the number of issues in the resulting ontologies defects can still be introduced into the ontology due to improper use or misinterpretation of the patterns. Thus, the quality of the developed ontologies is still a major concern. In this paper we address this issue by describing how ontology debugging and matching can be integrated in a state-of-the-art ontology development methodology based on ontology design patterns- the eXtreme Design methodology, and show the advantages in a case study based on a real world ontology.

    Place, publisher, year, edition, pages
    Rheinisch-Westfaelische Technische Hochschule Aachen University, 2015
    Series
    CEUR Workshop Proceedings, ISSN 1613-0073 ; 1461
    National Category
    Media and Communication Technology
    Identifiers
    urn:nbn:se:liu:diva-121794 (URN)
    Conference
    6th Workshop on Ontology and Semantic Web Patterns (WOP 2015), Bethlehem, Pensylvania, USA, October 11, 2015
    Funder
    EU, FP7, Seventh Framework Programme, FP7-IP-608142CUGS (National Graduate School in Computer Science)Swedish e‐Science Research Center
    Available from: 2015-10-06 Created: 2015-10-06 Last updated: 2017-08-21Bibliographically approved
  • Public defence: 2017-09-29 09:15 ACAS, A-huset, Linköping
    Kanda, Wisdom
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Stimulating the diffusion of environmental technologies through export2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Contemporary environmental problems represent complex societal challenges, and as these problems become increasingly global, the international diffusion of environmental technologies is essential. One way to diffuse technologies internationally is through export. Despite the potential benefits from the adoption of environmental technologies, their export is stifled by externalities and free-rider problems.

    From this background, the aim of this thesis is to analyse how to stimulate the diffusion of environmental technologies through export. This aim is operationalised using four research questions, which focus on governmental initiatives to promote environmental technology export and their perceived effectiveness among targeted firms, obstacles to and drivers for export among municipally owned companies, the use of international city networks to facilitate environmental technology export and components of business concepts for environmental technology export. These questions are explored in the Swedish context using document analyses, interviews and internet surveys in a compilation thesis which consists of a cover essay and an appendix of five scientifically peer-reviewed and published journal articles.

    The conclusions are that governmental export promotion initiatives are often generic for all kinds of exporters, including environmental technologies, and comprise financial support, information provision, education and training, and trade and mobility-related programs, often with little incorporation of the specific characteristics of environmental technologies which many exporters perceive as ineffective. Municipally owned companies experience different barriers to and drivers for engaging in international activities compared to privately owned companies, and are often involved in international projects which are not always commercial export. International city networks serve as important arenas for bi-directional information sharing and learning regarding market characteristics, environmental challenges and potential solutions, building legitimacy for technologies and their suppliers. Regarding components of business concepts for the export of environmental technologies, regulation, legitimacy and private-public partnership are identified as particularly important based on the complexity and systemic nature of environmental technologies.

    Altogether, this thesis makes a contribution by conceptualising the export of environmental technologies with emphasis on technology characteristics, the technology supplier including their business concepts, obstacles to and drivers for export, technology adopters and their characterisation, communication channels and the diffusion context. For policy makers, a dynamic approach to environmental technology export promotion, in which specific attributes of environmental technologies and their suppliers are considered along their international business development, is suggested as a complement to existing generic initiatives. The possibility to provide such support should be reconciled with resource effectiveness, heterogeneity among companies and the complementary role of governmental interventions to market initiatives. Finally, partnerships between publicly and privately owned companies are suggested as particularly relevant since they build on the long-term experience, functioning proof-of-concept and legitimacy of publicly owned companies together with the competitiveness and flexibility of privately owned companies. These attributes could help overcome the liabilities of foreignness and newness, as well as resource constraints which challenge environmental technology export.

    List of papers
    1. Promoting the export of environmental technologies: An analysis of governmental initiatives from eight countries
    Open this publication in new window or tab >>Promoting the export of environmental technologies: An analysis of governmental initiatives from eight countries
    2016 (English)In: Environmental Development, ISSN 2211-4645, E-ISSN 2211-4653, Vol. 17, 73-87 p.Article in journal (Refereed) Published
    Abstract [en]

    Export represents a means for the diffusion of environmental technologies with potential socio-economic and environmental benefits. However, environmental technology providers experience export barriers which stifle export and thus several governments continue to formulate export promotion initiatives towards this sector. Although export promotion is identified as essential in the environmental technology policy literature, it is yet to receive attention as to which initiatives are available in different countries including their potential relevance for environmental sustainability. Such knowledge is fundamental for policy learning and transfer including identification of good practices.

    To address this knowledge gap, we use market failure and comparative public policy theories to analyse export promotion initiatives from export promotion and export credit agencies across eight countries in Asia, Europe, and North America. Three major conclusions emerge: (1) governmental initiatives to promote environmental technology export can be categorised under financial aid, information provision, education and training, and trade mobility programs; (2) policy choices regarding promotion initiatives are mediated by the institutional context and interests of policy actors (3) relevant aspects of such initiatives for environmental sustainability include the incorporation of particular environmental technology characteristics in initiative formulation, and the prioritisation between different technology and markets types for implementation.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keyword
    Environmental technology; Export promotion, Market failure, Comparative public policy, Technology policy
    National Category
    Environmental Management
    Identifiers
    urn:nbn:se:liu:diva-122234 (URN)10.1016/j.envdev.2015.09.009 (DOI)
    Projects
    Megatech project
    Funder
    VINNOVA
    Available from: 2015-10-24 Created: 2015-10-24 Last updated: 2017-08-23Bibliographically approved
    2. Governmental export promotion initiatives: awareness, participation, and perceived effectiveness among Swedish environmental technology firms
    Open this publication in new window or tab >>Governmental export promotion initiatives: awareness, participation, and perceived effectiveness among Swedish environmental technology firms
    2015 (English)In: Journal of Cleaner Production, ISSN 0959-6526, Vol. 98, 222-228 p.Article in journal (Refereed) Published
    Abstract [en]

    Some countries rely heavily on exports as an essential component of their economic competitiveness. With the current trends in economic globalization, promoting exports has become a common strategy to boost economic growth. Exports of environmental technologies represent a new window of opportunity for economic growth and a contribution to global sustainability. With this in mind, national governments have designed initiatives that aim to promote exports within this sector. To address their objectives, governments provide initiatives to promote foreign commerce with their environmental technology sector. This article assesses the awareness, participation, and perceived effectiveness of such governmental initiatives to promote exports among Swedish environmental technology firms. An Internet survey was sent to 693 Swedish environmental technology companies, previously identified and classified, with a 25% response rate. The responses show a relatively high export orientation although a majority of the respondents claimed they were unaware of governmental initiatives that fit their particular export needs. The companies that did find appropriate governmental initiatives showed a high level of participation in such initiatives, but only a few of these participants could relate their participation to actual exports. The findings suggest there is a need to design support instruments based on the particular characteristics of the environmental technology sector rather than to offer generic solutions for such export promotion.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keyword
    Environmental technology, Technology diffusion, Market failures, Perceived effectiveness, Firm-level analysis
    National Category
    Environmental Management
    Identifiers
    urn:nbn:se:liu:diva-102196 (URN)10.1016/j.jclepro.2013.11.013 (DOI)000356194300023 ()
    Projects
    Megatech
    Funder
    VINNOVA
    Available from: 2013-12-03 Created: 2013-12-03 Last updated: 2017-08-23
    3. Export of environmental technologies by publicly-owned companies: Approaches, drivers and obstacles among Swedish municipal companies
    Open this publication in new window or tab >>Export of environmental technologies by publicly-owned companies: Approaches, drivers and obstacles among Swedish municipal companies
    2016 (English)In: European Planning Studies, ISSN 0965-4313, E-ISSN 1469-5944, Vol. 24, no 12, 2175-2196 p.Article in journal (Refereed) Published
    Abstract [en]

    This article focuses on the export of environmental technology by publicly-owned companies. The export of such technologies has the potential to contribute to economic competitiveness and environmental sustainability. However, research on this emerging topic has so far largely focused on privately-owned SMEs compared to publicly-owned companies. Using interviews with twelve Swedish municipally-owned companies which develop such systems and a survey with thirty-six others, we analyse their approaches, drivers for and obstacles to export. These companies use a combination of different approaches such as subsidiaries, independent projects, licensing and private-public partnerships to engage in export. However, in contrast to private companies which are often driven by internal factors such as extra sales, these municipally-owned companies are largely motivated by external factors such as customer requests and opportunities to contribute to environmental sustainability. Furthermore, their main export barriers relate to differences between the business culture and political systems in their home and target markets. Their export experiences are influenced by their municipal ownership, the types of technologies they develop and the institutional contexts within which they operate. This study reveals an actor type struggling to find a balance between domestic obligations and commercialization in international markets.

    Place, publisher, year, edition, pages
    Taylor & Francis Group, 2016
    Keyword
    publicly-owned companies, global sustainability, large technical systems, technology diffusion, export, waste management
    National Category
    Business Administration
    Identifiers
    urn:nbn:se:liu:diva-133042 (URN)10.1080/09654313.2016.1251881 (DOI)000390144900005 ()
    Note

    Funding agencies: Tekniska Verkens Industrial Ecology Research Programme under the BMEX project (Business Models for Market Expansion of Swedish Municipal Companies)

    Available from: 2016-12-08 Created: 2016-12-08 Last updated: 2017-08-23Bibliographically approved
    4. Analyzing international city networks for sustainability: A study of five major Swedish cities
    Open this publication in new window or tab >>Analyzing international city networks for sustainability: A study of five major Swedish cities
    2016 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 134, no part A, 61-69 p.Article in journal (Refereed) Published
    Abstract [en]

    This article studies five Swedish cities, their membership in international city networks, the different motivations for such membership, and their administrations’ expected and perceived benefits. Particular focus is put on sustainability, environmental technology, and municipal companies as potential beneficiaries of such network membership. This study is motivated by the fact that city networks can potentially contribute to global sustainability goals by accelerating the diffusion of innovations, giving members access to bidirectional information flows, improving the user-producer relationship, and providing legitimacy in the potential recipient regimes.

    The study relies on a documentation review, the collection of data from the websites of the studied cities and numerous international city networks, and interviews with city officials responsible for international city networks. It was found that four of the five studied cities are active members of international networks for sustainability, but also that there are large gaps between the two largest cities and the rest when it comes to the number of memberships and the geographical outreach they have through the networks they belong to.

    Some city officials claim that it is easier to be active in national networks than in international networks, due to time requirements and coordination among so many members. However, city officials see benefits for their municipal companies when they are members of international networks, and these companies are usually independent when it comes to choosing and administering their memberships. It was found that it is difficult to measure direct benefits from network membership, and link improvements in the studied cities to participation in a particular network (with the exception of groups created for a specific infrastructure project, reported as “networks” by the administrations). In addition, there is no apparent direct correlation between membership and diffusion of environmental solutions from municipal companies. However, the administrations expect indirect benefits such as gaining legitimacy and access to milieus where they can share information and best practices, which could lead to the improvement of both local and global environmental conditions.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keyword
    Legitimacy;Information Flows;Knowledge Sharing;Municipal Companies;Environmental Technology
    National Category
    Environmental Management
    Identifiers
    urn:nbn:se:liu:diva-121814 (URN)10.1016/j.jclepro.2015.09.093 (DOI)000382409700007 ()
    Note

    Funding agencies: Swedish Governmental Agency for Innovation Systems (VINNOVA); Swedish Energy Agency; Tekniska Verken AB

    Available from: 2015-10-07 Created: 2015-10-07 Last updated: 2017-08-23
    5. Components of business concepts for the diffusion of large scaled environmental technology systems
    Open this publication in new window or tab >>Components of business concepts for the diffusion of large scaled environmental technology systems
    2016 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 128, 156-167 p.Article in journal (Refereed) Published
    Abstract [en]

    Strategies for sustainable development are arguably part of the most discussed issues among political and corporate actors. These discussions are spurred by global challenges such as climate change, urbanization, and critical natural resource depletion. Sustainable development will require deep structural and wide-reaching changes in current institutions, technologies, and businesses. Furthermore, new approaches are needed to facilitate the development, diffusion, and implementation of environmental technologies. In the academic discourse different concepts, e.g., ecodesign and Product/Service System design, have been proposed within the framework of sustainable development. To deliver even more system-wide environmental improvements, these concepts have been challenged to be expanded in focus beyond products and services to include large technical systems encompassing non-technological dimensions. Motivated by these, the goal of this article is twofold. First, to offer an expanded view on ecodesign of product/service systems using a perspective of large technical systems. Second, to propose and discuss important components to consider when developing business concepts for the diffusion of large scaled environmental technology systems such as district heating supply, waste management, and renewable energy systems. Using qualitative semi-structured interviews and company documentation analysis, this study examines five companies that develop and diffuse large scaled environmental technology systems. As a result of these case studies, we propose components of business concepts that incorporate both technological and non-technological dimensions. Our proposed business concept components are: market (including regulation), finance, resources, activities, partnership (especially public-private partnership), ownership and responsibility, and legitimacy. Regulation, public-private partnership, and legitimacy are particularly important in the diffusion of large scaled environmental technology systems.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keyword
    Large technical systems, Business model, Technology diffusion, Product/Service System, Ecodesign
    National Category
    Environmental Management
    Identifiers
    urn:nbn:se:liu:diva-122235 (URN)10.1016/j.jclepro.2015.10.040 (DOI)000378568800013 ()
    Projects
    BMEX project
    Note

    Funding agencies: We are grateful to Tekniska Verken's Industrial Ecology Research Programme for their financial support to undertake this study as part the BMEX project (Business Models for Market Expansion of Swedish Municipal Companies). We also want to express our sincere gratitude to the interviewees for making time to participate in the interviews. Special thanks also go to Sahar Sadri of Linkoping University for taking part in conducting the interviews.

    Available from: 2015-10-24 Created: 2015-10-24 Last updated: 2017-08-23Bibliographically approved
  • Public defence: 2017-09-29 13:00 Belladonna, ing 76/78, Linköping
    Wennerholm, Carina
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Medicine and Health Sciences.
    Risks for cardiovascular disease in middle-aged women in different social environments2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: The importance of the social environment and human life conditions for public health was early recognized in community medicine. Despite major reductions in recent decades, cardiovascular diseases (CVD) is one of the leading causes of mortality and morbidity for both genders in all European countries. 

    Aim: The overall aim of this thesis was to increase our knowledge of factors in the social environment and of individual psychosocial factors that could explain why some women in working ages are affected by cardiovascular diseases.

    Methods: The Swedish sample comes from the urban population in two major cities in a region in the south-east of Sweden, the Twin cities. According to their social history they could be labelled a “blue-collar” and a “white-collar” city. Cardiovascular morbidity data in all papers for the Twin cities was derived from a computerized population-based administrative Health Care Register (HCR). In Paper IV, we made a comparative study between Sweden and Scotland, the Scottish data comes from the Scottish Health Survey.

    Results: In Paper I, the cumulative incidence of different cardiovascular diagnoses for younger and also elderly men and women were significantly higher in the population of the blue collar city in all ages and for both sexes. The qualitative interviews of women after an MI, in Paper II, the findings revealed a broad picture of social factors, life circumstances, personalities and, not least, psychosocial factors that are important to middle-aged women who have suffered an MI. Paper III demonstrated that women with a high level of the personality trait “being a Good Girl” reported significantly more psychosocial risk factors for CVD and more commonly report chest pain without seeking medical care, no increased incidence for various CVD-diagnoses were found. The comparative study (Paper IV) clearly showed that Scottish middle-aged women are – relative to Swedish women - particularly affected by a worse profile of CVD risks, even after adjustment for education.  

    Conclusions: The social environment is of importance for cardiovascular risks and cardiovascular morbidity and mortality. This has been shown in Swedish Twin cities context and also in comparative studies between Swedish and Scottish women. The thesis gives strong implications for an upstream public health approach initiating long-term community intervention program in the blue collar city and among Scottish middle-aged women.

    List of papers
    1. Cardiovascular disease occurrence in two close but different social environments
    Open this publication in new window or tab >>Cardiovascular disease occurrence in two close but different social environments
    Show others...
    2011 (English)In: INTERNATIONAL JOURNAL OF HEALTH GEOGRAPHICS, ISSN 1476-072X, Vol. 10, no 5Article in journal (Refereed) Published
    Abstract [en]

    Background: Cardiovascular diseases estimate to be the leading cause of death and loss of disability-adjusted life years globally. Conventional risk factors for cardiovascular diseases only partly account for the social gradient. The purpose of this study was to compare the occurrence of the most frequent cardiovascular diseases and cardiovascular mortality in two close cities, the Twin cities. Methods: We focused on the total population in two neighbour and equally sized cities with a population of around 135 000 inhabitants each. These twin cities represent two different social environments in the same Swedish county. According to their social history they could be labelled a "blue-collar" and a "white-collar" city. Morbidity data for the two cities was derived from an administrative health care register based on medical records assigned by the physicians at both hospitals and primary care. The morbidity data presented are cumulative incidence rates and the data on mortality for ischemic heart diseases is based on official Swedish statistics. Results: The cumulative incidence of different cardiovascular diagnoses for younger and also elderly men and women revealed significantly differences for studied cardiovascular diagnoses. The occurrence rates were in all aspects highest in the population of the "blue-collar" twin city for both sexes. Conclusions: This study revealed that there are significant differences in risk for cardiovascular morbidity and mortality between the populations in the studied different social environments. These differences seem to be profound and stable over time and thereby give implication for public health policy to initiate a community intervention program in the "blue-collar" twin city.

    Place, publisher, year, edition, pages
    BioMed Central, 2011
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-66880 (URN)10.1186/1476-072X-10-5 (DOI)000286525800001 ()
    Note
    Original Publication: Carina Wennerholm, Björn Grip, AnnaKarin Johansson, Hans Nilsson, Marja-Liisa Honkasalo and Tomas Faresjö, Cardiovascular disease occurrence in two close but different social environments, 2011, INTERNATIONAL JOURNAL OF HEALTH GEOGRAPHICS, (10), 5. http://dx.doi.org/10.1186/1476-072X-10-5 Licensee: BioMed Central http://www.biomedcentral.com/Available from: 2011-03-22 Created: 2011-03-21 Last updated: 2017-09-18
    2. Life before myocardial infarction - a qualitative study of middle-aged women
    Open this publication in new window or tab >>Life before myocardial infarction - a qualitative study of middle-aged women
    2014 (English)In: Health, ISSN 1949-4998, E-ISSN 1949-5005, Vol. 6, 2765-2774 p.Article in journal (Refereed) Published
    Abstract [en]

    The health burden of myocardial infarction is rising for middle-aged women and they are underrepresented in research of cardiovascular diseases. The aim of this qualitative study was to explore how life had been for middle-aged women before they suffered a myocardial infarction (MI). Through a health care register, we identified all women (n = 46) under 65 years of age in a defined region in southeast Sweden who had suffered an MI the past 2 years and a strategic selection of n = 16 women from these was made. These selected women were interviewed and their narratives were interpreted by qualitative content analysis. The qualitative interviews generated five general themes: “Serious life events”, “Negative affectivity”, “Loneliness”, “Being a good girl” and “Lack of control”. The interviews revealed that many of these women had been exposed to extreme and repeated traumatic life events in their lives. Many had a cynical attitude towards others, felt lonely and experienced a lack of social support. Many of these women endeavored to “be a good girl”, which was a special psychosocial phenomenon found. This study uncovered that these women before they suffered an MI were affected by a variety of psychosocial factors. The study stresses the importance of psychosocial risk factors in the assessment of middle-aged women’s risk profile for MI. A general conclusion for clinical practice is that in the assessment of the individual risk for myocardial infarction for middle-aged women, potential psychosocial factors might also be considered.

    Place, publisher, year, edition, pages
    Wuhan, Hubei Province, China: Scientific Research Publishing, 2014
    National Category
    Family Medicine
    Identifiers
    urn:nbn:se:liu:diva-115734 (URN)10.4236/health.2014.620316 (DOI)
    Available from: 2015-03-18 Created: 2015-03-18 Last updated: 2017-09-18Bibliographically approved
    3. Two tales of cardiovascular risks-middle-aged women living in Sweden and Scotland: a cross-sectional comparative study
    Open this publication in new window or tab >>Two tales of cardiovascular risks-middle-aged women living in Sweden and Scotland: a cross-sectional comparative study
    Show others...
    2017 (English)In: BMJ Open, ISSN 2044-6055, E-ISSN 2044-6055, Vol. 7, no 8, e016527Article in journal (Refereed) Published
    Abstract [en]

    OBJECTIVES: To compare cardiovascular risk factors as well as rates of cardiovascular diseases in middle-aged women from urban areas in Scotland and Sweden.

    DESIGN: Comparative cross-sectional study.

    SETTING: Data from the general population in urban areas of Scotland and the general population in two major Swedish cities in southeast Sweden, south of Stockholm.

    PARTICIPANTS: Comparable data of middle-aged women (40-65 years) from the Scottish Health Survey (n=6250) and the Swedish QWIN study (n=741) were merged together into a new dataset (n=6991 participants).

    MAIN OUTCOME MEASURE: We compared middle-aged women in urban areas in Sweden and Scotland regarding risk factors for cardiovascular disease (CVD), CVD diagnosis, anthropometrics, psychological distress and lifestyle.

    RESULTS: In almost all measurements, there were significant differences between the countries, favouring the Swedish women. Scottish women demonstrated a higher frequency of alcohol consumption, smoking, obesity, low vegetable consumption, a sedentary lifestyle and also more psychological distress. For doctor-diagnosed coronary heart disease, there were also significant differences, with a higher prevalence among the Scottish women.

    CONCLUSIONS: This is one of the first studies that clearly shows that Scottish middle-aged women are particularly affected by a worse profile of CVD risks. The profound differences in CVD risk and outcome frequency in the two populations are likely to have arisen from differences in the two groups of women's social, cultural, political and economic environments.

    Place, publisher, year, edition, pages
    London: BMJ Publishing Group Ltd, 2017
    Keyword
    cardiovascular risk factors, comparative study, lifestyle, middle-aged women, psychological distress, public health
    National Category
    Public Health, Global Health, Social Medicine and Epidemiology
    Identifiers
    urn:nbn:se:liu:diva-140935 (URN)10.1136/bmjopen-2017-016527 (DOI)28790040 (PubMedID)2-s2.0-85027162863 (Scopus ID)
    Available from: 2017-09-18 Created: 2017-09-18 Last updated: 2017-09-20Bibliographically approved
  • Public defence: 2017-09-29 13:15 Ada Lovelace, Hus B, Linköping
    Hammar, Karl
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering. Tekniska Högskolan i Jönköping.
    Content Ontology Design Patterns: Qualities, Methods, and Tools2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Ontologies are formal knowledge models that describe concepts and relationships and enable data integration, information search, and reasoning. Ontology Design Patterns (ODPs) are reusable solutions intended to simplify ontology development and support the use of semantic technologies by ontology engineers. ODPs document and package good modelling practices for reuse, ideally enabling inexperienced ontologists to construct high-quality ontologies. Although ODPs are already used for development, there are still remaining challenges that have not been addressed in the literature. These research gaps include a lack of knowledge about (1) which ODP features are important for ontology engineering, (2) less experienced developers' preferences and barriers for employing ODP tooling, and (3) the suitability of the eXtreme Design (XD) ODP usage methodology in non-academic contexts.

    This dissertation aims to close these gaps by combining quantitative and qualitative methods, primarily based on five ontology engineering projects involving inexperienced ontologists. A series of ontology engineering workshops and surveys provided data about developer preferences regarding ODP features, ODP usage methodology, and ODP tooling needs. Other data sources are ontologies and ODPs published on the web, which have been studied in detail. To evaluate tooling improvements, experimental approaches provide data from comparison of new tools and techniques against established alternatives.

    The analysis of the gathered data resulted in a set of measurable quality indicators that cover aspects of ODP documentation, formal representation or axiomatisation, and usage by ontologists. These indicators highlight quality trade-offs: for instance, between ODP Learnability and Reusability, or between Functional Suitability and Performance Efficiency. Furthermore, the results demonstrate a need for ODP tools that support three novel property specialisation strategies, and highlight the preference of inexperienced developers for template-based ODP instantiation---neither of which are supported in prior tooling. The studies also resulted in improvements to ODP search engines based on ODP-specific attributes. Finally, the analysis shows that XD should include guidance for the developer roles and responsibilities in ontology engineering projects, suggestions on how to reuse existing ontology resources, and approaches for adapting XD to project-specific contexts.

  • Public defence: 2017-09-29 13:15 TEMCAS, Hus Tema, Linköping
    Littmarck, Sofia
    Linköping University, Department of Thematic Studies, Department of Child Studies. Linköping University, Faculty of Arts and Sciences.
    Barn, föräldrar, välfärdsstat: Den politiska debatten om föräldrautbildning och föräldrastöd 1964-20092017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The political debate concerning parent education and parenting support between 1964 and 2009 has been scrutinized in this study in the light of the development of and changes in the welfare state. The investigation is based upon the analysis of official government inquiries and parliamentary papers dealing with parent education and parenting support. This study analyzes the different choices in the organization of welfare relevant to children and the family for which political actors have argued, and it examines the views on the relations between children, parents, family and the welfare state that were expressed in the argumentation. Parent education and parenting support aim at changing the living conditions of children by means of the parents. The study shows that the interest in this type of investment has been shared by both the political left and center-right, but from different arguments and political visions on how welfare for children and families with children should be organized, as well as from different views of the role of parent education and parenting support in the welfare.

  • Public defence: 2017-10-03 10:15 C3, Hus C, Linköping
    Ryberg, Ann-Britt
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering. Combitech AB, Trollhättan, Sweden.
    Metamodel-Based Multidisciplinary Design Optimization of Automotive Structures2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Multidisciplinary design optimization (MDO) can be used in computer aided engineering (CAE) to efficiently improve and balance performance of automotive structures. However, large-scale MDO is not yet generally integrated within automotive product development due to several challenges, of which excessive computing times is the most important one. In this thesis, a metamodel-based MDO process that fits normal company organizations and CAE-based development processes is presented. The introduction of global metamodels offers means to increase computational efficiency and distribute work without implementing complicated multi-level MDO methods.

    The presented MDO process is proven to be efficient for thickness optimization studies with the objective to minimize mass. It can also be used for spot weld optimization if the models are prepared correctly. A comparison of different methods reveals that topology optimization, which requires less model preparation and computational effort, is an alternative if load cases involving simulations of linear systems are judged to be of major importance.

    A technical challenge when performing metamodel-based design optimization is lack of accuracy for metamodels representing complex responses including discontinuities, which are common in for example crashworthiness applications. The decision boundary from a support vector machine (SVM) can be used to identify the border between different types of deformation behaviour. In this thesis, this information is used to improve the accuracy of feedforward neural network metamodels. Three different approaches are tested; to split the design space and fit separate metamodels for the different regions, to add estimated guiding samples to the fitting set along the boundary before a global metamodel is fitted, and to use a special SVM-based sequential sampling method. Substantial improvements in accuracy are observed, and it is found that implementing SVM-based sequential sampling and estimated guiding samples can result in successful optimization studies for cases where more conventional methods fail.

    List of papers
    1. Multidisciplinary design optimisation methods for automotive structures
    Open this publication in new window or tab >>Multidisciplinary design optimisation methods for automotive structures
    2017 (English)In: International Journal of Automotive and Mechanical Engineering, ISSN 2229-8649, Vol. 14, no 1, 4050-4067 p.Article in journal (Refereed) Published
    Abstract [en]

    Multidisciplinary design optimisation (MDO) can be used as an effective tool to improve the design of automotive structures. Large-scale MDO problems typically involve several groups who must work concurrently and autonomously in order to make the solution process efficient. In this article, the formulations of existing MDO methods are compared and their suitability is assessed in relation to the characteristics of automotive structural applications. Both multi-level and single-level optimisation methods are considered. Multi-level optimisation methods distribute the design process but are complex. When optimising automotive structures, metamodels are often required to relieve the computational burden of detailed simulation models. The metamodels can be created by individual groups prior to the optimisation process, and thus offer a way of distributing work. Therefore, it is concluded that a single-level method in combination with meta-models is the most straightforward way of implementing MDO into the development of automotive structures. If the benefits of multi-level optimisation methods, in a special case, are considered to compensate for their drawbacks, analytical target cascading has a number of advantages over collaborative optimisation, but both methods are possible choices.

    Place, publisher, year, edition, pages
    Pekan, Malaysia: Universiti Malaysia Pahang Publishing, 2017
    Keyword
    Multidisciplinary design optimisation, single-level optimisation methods, multilevel optimisation methods, automotive structures
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-140876 (URN)10.15282/ijame.14.1.2017.17.0327 (DOI)
    Available from: 2017-09-14 Created: 2017-09-14 Last updated: 2017-09-19Bibliographically approved
    2. A metamodel-based multidisciplinary design optimization process for automotive structures
    Open this publication in new window or tab >>A metamodel-based multidisciplinary design optimization process for automotive structures
    2015 (English)In: Engineering with Computers, ISSN 0177-0667, E-ISSN 1435-5663, Vol. 31, no 4, 711-728 p.Article in journal (Refereed) Published
    Abstract [en]

    Automotive companies continuously strive to design better products faster and more cheaply using simulation models to evaluate every possible aspect of the product. Multidisciplinary design optimization (MDO) can be used to find the best possible design taking into account several disciplines simultaneously, but it is not yet fully integrated within automotive product development. The challenge is to find methods that fit company organizations and that can be effectively integrated into the product development process. Based on the characteristics of typical automotive structural MDO problems, a metamodel-based MDO process intended for large-scale applications with computationally expensive simulation models is presented and demonstrated in an example. The process is flexible and can easily fit into existing organizations and product development processes where different groups work in parallel. The method is proven to be efficient for the discussed example and improved designs can also be obtained for more complex industrial cases with comparable characteristics.

    Place, publisher, year, edition, pages
    Springer, 2015
    Keyword
    Multidisciplinary design optimization (MDO); metamodel-based design optimization (MBDO); automotive structures
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-88135 (URN)10.1007/s00366-014-0381-y (DOI)000360859000004 ()
    Available from: 2013-01-30 Created: 2013-01-30 Last updated: 2017-09-14Bibliographically approved
    3. Spot weld reduction methods for automotive structures
    Open this publication in new window or tab >>Spot weld reduction methods for automotive structures
    2016 (English)In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 53, no 4, 923-934 p.Article in journal (Refereed) Published
    Abstract [en]

    Spot welds are commonly used to join steel sheets in automotive structures. The number and layout of these spot welds are vital for the performance of the structure. However, reducing the number of spot welds will cut both production time and cost. This article presents three different methods of reducing the number of spot welds in automotive structures: ranking-based selection, topology optimization and size optimization of a parameterized model. The methods are compared in a simple example and it is found that the latter two methods have the best potential of reducing the number of spot welds. Topology optimization requires less preparation and computational effort as compared to size optimization of a parameterized model. However, the method is primarily suitable for studies where load cases involving linear systems are judged to be most important. Otherwise, size optimization of a parameterized model is probably a better choice. The topology optimization approach is successfully demonstrated in a full-scale industrial application example and confirms that the method is useful within contemporary product development.

    Place, publisher, year, edition, pages
    SPRINGER, 2016
    Keyword
    Spot weld optimization; Multidisciplinary design optimization (MDO); Topology optimization; Size optimization; Metamodels; Automotive structures
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-127430 (URN)10.1007/s00158-015-1355-4 (DOI)000373023800018 ()
    Note

    Funding Agencies|Vinnova FFI project

    Available from: 2016-05-01 Created: 2016-04-26 Last updated: 2017-09-14
  • Public defence: 2017-10-03 13:15 Ada Lovelace, hus B, Linköping
    Ståhlberg, Simon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Methods for Detecting Unsolvable Planning Instances using Variable Projection2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this thesis we study automated planning, a branch of artificialintelligence, which deals with construction of plans. A plan is typically an action sequence that achieves some specific goal. In particular, we study unsolvable planning instances, i.e. there is no plan. Historically, this topic has been neglected by the planning community, and up to recently the International Planning Competition has only evaluated planners on solvable planning instances. For many applications we can know, e.g. by design, that there is a solution, but this cannot be a general assumption. One example is penetration testing in computer security, where a system inconsidered safe if there is no plan for intrusion. Other examples are resource bound planning instances that have insufficient resources to achieve the goal.

    The main theme of this thesis is to use variable projection to prove unsolvability of planning instances. We implement and evaluate two planners: the first checks variable projections with the goal of finding an unsolvable projection, and the second builds a pattern collection to provide dead-end detection. In addition to comparing the planners to existing planners, we also utilise a large computer cluser to statistically assess whether they can be optimised further. On the benchmarks of planning instances that we used, it turns out that further improvement is likely to come from supplementary techniques rather than optimisation. We pursued this and enhanced variable projections with mutexes, which yielded a very competitive planner. We also inspect whether unsolvable variable projections tend to be composed of variables that play different roles, i.e. they are not 'similar'. We devise a variable similarity measure to rate how similar two variables are on a scale, and statistically analyse it. The measure can differentiate between unsolvable and solvable planning instances quite well, and is integrated into our planners. We also define a binary version of the measure, namely, that two variables are isomorphic if they behave exactly the same in some optimal solution (extremely similar). With the help of isomorphic variables we identified a computationally tractable class of planning instances that meet certain restrictions. There are several special cases of this class that are of practical interest, and this result encompass them.

  • Public defence: 2017-10-06 10:15 Ada Lovelace, Hus B, ingång 27, Linköping
    Simon, Daniel
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Fighter Aircraft Maneuver Limiting Using MPC: Theory and Application2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Flight control design for modern fighter aircraft is a challenging task. Aircraft are dynamical systems, which naturally contain a variety of constraints and nonlinearities such as, e.g., maximum permissible load factor, angle of attack and control surface deflections. Taking these limitations into account in the design of control systems is becoming increasingly important as the performance and complexity of the aircraft is constantly increasing.

    The aeronautical industry has traditionally applied feedforward, anti-windup or similar techniques and different ad hoc engineering solutions to handle constraints on the aircraft. However these approaches often rely on engineering experience and insight rather than a theoretical foundation, and can often require a tremendous amount of time to tune.

    In this thesis we investigate model predictive control as an alternative design tool to handle the constraints that arises in the flight control design.

    We derive a simple reference tracking MPC algorithm for linear systems that build on the dual mode formulation with guaranteed stability and low complexity suitable for implementation in real time safety critical systems.

    To reduce the computational burden of nonlinear model predictive control we propose a method to handle the nonlinear constraints, using a set of dynamically generated local inner polytopic approximations. The main benefit of the proposed method is that while computationally cheap it still can guarantee recursive feasibility and convergence.

    An alternative to deriving MPC algorithms with guaranteed stability properties is to analyze the closed loop stability, post design. Here we focus on deriving a tool based on Mixed Integer Linear Programming for analysis of the closed loop stability and robust stability of linear systems controlled with MPC controllers.

    To test the performance of model predictive control for a real world example we design and implement a standard MPC controller in the development simulator for the JAS 39 Gripen aircraft at Saab Aeronautics. This part of the thesis focuses on practical and tuning aspects of designing MPC controllers for fighter aircraft. Finally we have compared the MPC design with an alternative approach to maneuver limiting using a command governor.

  • Public defence: 2017-10-06 13:15 ACAS, A-huset, Linköping, Sweden
    Lång, Elisabeth
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Short- and Long-Term Influences of Education, Health Indicators, and Crime on Labor Market Outcomes: Five Essays in Empirical Labor Economics2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of this thesis is to improve the understanding of how several individual characteristics, namely education (years of schooling), health indicators (height, weight, smoking, alcohol consumption, and exercise), criminal behavior, and crime victimization, influence labor market outcomes in the short and long run. The first part of the thesis consists of three studies in which I adopt a within-twin-pair difference approach to analyze how education, health indicators, and earnings are associated with each other over the life cycle. The second part of the thesis includes two studies in which I use field experiments in order to test the employability of exoffenders and crime victims.

    The first essay, Learning for life?, describes an analysis of the education premium in earnings and health-related behaviors throughout adulthood among twins. The results show that the education premium in earnings, net of genetic inheritance, is rather small over the life cycle but increases with the level of education. The results also show that the education premium in health-related behaviors is mainly concentrated on smoking habits. The influences of education on earnings and health-related behaviors seem to work independently of each other, and there are no signs that health-related behaviors influence the education premium in earnings or vice versa.

    The second essay, Blowing up money?, details an analysis of the association between smoking and earnings in two different historical social contexts in Sweden: the 1970s and the 2000s. I also consider possible differences in this association in the short and long run as well as between the sexes. The results show that the earnings penalty for smoking is much stronger in the 2000s as compared to the 1970s (for both sexes) and that it is larger in the long run as compared to the short run (for men).

    The third essay, Two by two, inch by inch, describes an analysis of the height premium among Swedish twins. The results show that the height premium is relatively constant over the life cycle and that it is larger below median height for men and above median height for young women. The estimates are similar for monozygotic and dizygotic twins, indicating that environmentally and genetically induced height differences are similarly associated with earnings over the life cycle.

    The fourth essay, The employability of ex-offenders, published in IZA Journal of Labor Policy (2017), 6:6, details an analysis of whether male and female exoffenders are discriminated against when applying for jobs in the Swedish labor market. The results show that employers do discriminate against exoffenders but that the degree of discrimination varies across occupations. Discrimination against ex-offenders is pronounced in female-dominated and high-skilled occupations. The magnitude of discrimination against exoffenders does not vary by applicants’ sex.

    The fifth essay, Victimized twice?, describes an analysis of whether male and female crime victims are discriminated against when applying for jobs in the Swedish labor market. This study is the first to consider potential hiring discrimination against crime victims. The results show that employers do discriminate against crime victims. The discrimination varies with the sex of the crime victim and occupational characteristics and is concentrated among high-skilled jobs for female crime victims and among femaledominated jobs for male crime victims.

    List of papers
    1. The employability of ex-offenders: a field experiment in the Swedish labor market
    Open this publication in new window or tab >>The employability of ex-offenders: a field experiment in the Swedish labor market
    2017 (English)In: IZA Journal of Labor Policy, ISSN 2193-9004, E-ISSN 2193-9004, Vol. 6, no 1, 1-23 p.Article in journal (Refereed) Published
    Abstract [en]

    This paper presents the findings of a field experiment on hiring discrimination against ex-offenders in the Swedish labor market. Matched pairs of written job applications for fictitious male and female applicants with and without a past conviction of assault were sent to employers for nine different occupations. Results show that discrimination against ex-offenders exists, but the extent of it varies across occupations. The past conviction of assault was associated with 7–18 percentage point lower probability of receiving a positive employer response. Discrimination against ex-offenders was pronounced in female-dominated and high-skilled occupations. The magnitude of discrimination against ex-offenders did not vary by applicants’ sex.

    Place, publisher, year, edition, pages
    Springer, 2017
    Keyword
    Ex-offenders, Field experiments, Labor market discrimination
    National Category
    Economics
    Identifiers
    urn:nbn:se:liu:diva-140652 (URN)10.1186/s40173-017-0084-2 (DOI)
    Available from: 2017-09-06 Created: 2017-09-06 Last updated: 2017-09-06
  • Public defence: 2017-10-06 13:15 Ada Lovelace (former Visionen), B building, Linköping
    La Cognata, Cristina
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    High order summation-by-parts based approximations for discontinuous and nonlinear problems2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Numerical approximations using high order finite differences on summation-byparts (SBP) form are investigated for discontinuous and fully nonlinear systems of partial differential equations. Stability and conservation properties of the approximations are obtained through a weak imposition of interface and boundary conditions with the simultaneous-approximation-term (SAT) technique. The SBP-SAT approximations replicate the continuous integration by parts rule. From this property, well-posedness and integral properties of the continuous problem are mimicked, and energy estimates leading to stability are obtained.

    The first part of the thesis focuses on the simulations of discontinuous linear advection problems. An artificial interface is introduced, separating parts of the spatial domain characterized by different wave speeds. A set of flexible stability conditions at the interface are derived, which can be adapted to yield conservative or non-conservative approximations. This model can be interpreted as a simplified version of nonlinear problems involving jumps at shocks, or as a prototypical of wave propagation through different materials.

    In the second part of the thesis, the vorticity/stream function formulation of the nonlinear momentum equation for an incompressible inviscid fluid is considered. SBP operators are used to derive a new Arakawa-like Jacobian with mimetic properties by combining different consistent approximations of the convection terms. Energy and enstrophy conservation is obtained for periodic problems using schemes with arbitrarily high order of accuracy. These properties are crucial for long-term numerical calculations in climate and weather forecasts or ocean circulation predictions.

    The third and final contribution of the thesis is dedicated to the incompressible Navier-Stokes problem. First, different completely general formulations of energy bounding boundary conditions are derived for the nonlinear equations. The boundary conditions can be used at both far field and solid wall boundaries. The discretisation in time and space with weakly imposed initial and boundary conditions using the SBP-SAT framework is proved to be stable and the divergence free condition is approximated with the design order of the scheme. Next, the same formulations are considered in a linearised setting, whereupon the spectra associated with the initial boundary value problem and its SBP-SAT discretisation are derived using the Laplace-Fourier technique. The influence of different boundary conditions on the spectrum and in particular the convergence to steady state is studied.

    List of papers
    1. Well-posedness, stability and conservation for a discontinuous interface problem
    Open this publication in new window or tab >>Well-posedness, stability and conservation for a discontinuous interface problem
    2016 (English)In: BIT Numerical Mathematics, ISSN 0006-3835, E-ISSN 1572-9125, Vol. 56, no 2, 681-704 p.Article in journal (Refereed) Published
    Abstract [en]

    The advection equation is studied in a completely general two domain setting with different wave-speeds and a time-independent jump-condition at the interface separating the domains. Well-posedness and conservation criteria are derived for the initial-boundary-value problem. The equations are semi-discretized using a finite difference method on Summation-By-Part (SBP) form. The relation between the stability and conservation properties of the approximation are studied when the boundary and interface conditions are weakly imposed by the Simultaneous-Approximation-Term (SAT) procedure. Numerical simulations corroborate the theoretical findings.

    Place, publisher, year, edition, pages
    Springer, 2016
    Keyword
    Interface – Discontinuous coefficients problems – Initial boundary value problems – Well-posedness – Conservation – Stability – Interface conditions – High order accuracy – Summation-by-parts operators
    National Category
    Computational Mathematics
    Identifiers
    urn:nbn:se:liu:diva-121468 (URN)10.1007/s10543-015-0576-7 (DOI)000376580200016 ()
    Available from: 2015-09-21 Created: 2015-09-21 Last updated: 2017-09-05Bibliographically approved
    2. A new high order energy and enstrophy conserving Arakawa-like Jacobian differential operator
    Open this publication in new window or tab >>A new high order energy and enstrophy conserving Arakawa-like Jacobian differential operator
    2015 (English)In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 301, 167-177 p.Article in journal (Refereed) Published
    Abstract [en]

    A new high order Arakawa-like method for the incompressible vorticity equation in two-dimensions has been developed. Mimetic properties such as skew-symmetry, energy and enstrophy conservations for the semi-discretization are proved for periodic problems using arbitrary high order summation-by-parts operators. Numerical simulations corroborate the theoretical findings.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keyword
    Non-linear problems; Summation-by-parts operators; Jacobian; Mimetic schemes; High-order schemes; Stability; Finite difference
    National Category
    Mathematics
    Identifiers
    urn:nbn:se:liu:diva-121469 (URN)10.1016/j.jcp.2015.08.028 (DOI)000362379300010 ()
    Available from: 2015-09-21 Created: 2015-09-21 Last updated: 2017-09-05
    3. Energy Stable Boundary Conditions for the Nonlinear Incompressible Navier-Stokes Equations
    Open this publication in new window or tab >>Energy Stable Boundary Conditions for the Nonlinear Incompressible Navier-Stokes Equations
    2017 (English)Report (Other academic)
    Abstract [en]

    The nonlinear incompressible Navier-Stokes equations with boundary conditions at far fields and solid walls is considered. Two different formulations of boundary conditions are derived using the energy method. Both formulations are implemented in both strong and weak form and lead to an estimate of the velocity field. Equipped with energy bounding boundary conditions, the problem is approximated by using difference operators on summation-by-parts form and weak boundary and initial conditions. By mimicking the continuous analysis, the resulting semi-discrete as well as fully discrete scheme are shown to be provably stable, divergence free and high-order accurate.

    Place, publisher, year, edition, pages
    Linköping University Electronic Press, 2017. 31 p.
    Series
    LiTH-MAT-R, ISSN 0348-2960 ; 2017:9
    Keyword
    Navier-Stokes equations, incompressible, boundary conditions, energy estimate, stability, summation-by-parts, high-order accuracy, divergence free
    National Category
    Computational Mathematics
    Identifiers
    urn:nbn:se:liu:diva-139730 (URN)LiTH-MAT-R--2017/09--SE (ISRN)
    Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2017-09-05Bibliographically approved
    4. Spectral analysis of the incompressible Navier-Stokes equations with different boundary conditions
    Open this publication in new window or tab >>Spectral analysis of the incompressible Navier-Stokes equations with different boundary conditions
    2017 (English)Report (Other academic)
    Abstract [en]

    The influence of boundary conditions on the spectrum of the incompressible Navier-Stokes equations is studied. The spectra associated to different types of boundary conditions are derived using the Fourier-Laplace technique. In particular, the effect of various combinations of generalized in- and outgoing variables on the convergence to the steady state is investigated. The boundary conditions are analysed in both the continuous and semi-discrete problems. In the latter, high-order schemes in summation-by-parts form with weakly imposed boundary conditions are used to approximate the equations. Numerical calculations are performed and show that the discrete behaviour agrees with the theoretical analysis.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2017. 34 p.
    Series
    LiTH-MAT-R, ISSN 0348-2960 ; 2017:10
    Keyword
    Incompressible flows, Navier-Stokes, Fourier-Laplace technique, summation-by-parts, weak boundary conditions
    National Category
    Computational Mathematics
    Identifiers
    urn:nbn:se:liu:diva-139729 (URN)LiTH-MAT-R--2017/10—SE (ISRN)
    Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2017-09-05Bibliographically approved