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  • Public defence: 2017-05-05 13:15 Delta, Västerås
    Jonsson, Markus
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    Processes on Integer Partitions and Their Limit Shapes2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with processes on integer partitions and their limit shapes, with focus on deterministic and stochastic variants on one such process called Bulgarian solitaire. The main scientific contributions are the following.

    Paper I: Bulgarian solitaire is a dynamical system on integer partitions of n which converges to a unique fixed point if n=1+2+...+k is a triangular number. There are few results about the structure of the game tree, but when k tends to infinity the game tree itself converges to a structure that we are able to analyze. Its level sizes turns out to be a bisection of the Fibonacci numbers. The leaves in this tree structure are enumerated using Fibonacci numbers as well. We also demonstrate to which extent these results apply to the case when k is finite.

    Paper II: Bulgarian solitaire is played on n cards divided into several piles; a move consists of picking one card from each pile to form a new pile. In a recent generalization, σ-Bulgarian solitaire, the number of cards you pick from a pile is some function σ of the pile size, such that you pick σ(h) < h cards from a pile of size h. Here we consider a special class of such functions. Let us call σ well-behaved if σ(1) = 1 and if both σ(h) and h − σ(h) are non-decreasing functions of h. Well-behaved σ-Bulgarian solitaire has a geometric interpretation in terms of layers at certain levels being picked in each move. It also satisfies that if a stable configuration of n cards exists it is unique. Moreover, if piles are sorted in order of decreasing size then a configuration is convex if and only if it is a stable configuration of some well-behaved σ-Bulgarian solitaire. If sorted configurations are represented by Young diagrams and scaled down to have unit height and unit area, the stable configurations corresponding to an infinite sequence of well-behaved functions (σ1, σ2, ...) may tend to a limit shape Φ. We show that every convex Φ with certain properties can arise as the limit shape of some sequence of well-behaved σn. For the special case when σn(h) = ceil(qnh) for 0 < qn ≤ 1 (where ceil is the ceiling function rounding upward to the nearest integer), these limit shapes are triangular (in case qn2n → 0), or exponential (in case qn2n → ∞), or interpolating between these shapes (in case qn2n → C > 0).

    Paper III: We introduce pn-random qn-proportion Bulgarian solitaire (0 < pn,qn ≤ 1), played on n cards distributed in piles. In each pile, a number of cards equal to the proportion qn of the pile size rounded upward to the nearest integer are candidates to be picked. Each candidate card is picked with probability pn, independently of other candidate cards. This generalizes Popov's random Bulgarian solitaire, in which there is a single candidate card in each pile. Popov showed that a triangular limit shape is obtained for a fixed p as n tends to infinity. Here we let both pn and qn vary with n. We show that under the conditions qn2pnn/log n → ∞ and pnqn → 0 as n → ∞, the pn-random qn-proportion Bulgarian solitaire has an exponential limit shape.

    Paper IV: We consider two types of discrete-time Markov chains where the state space is a graded poset and the transitions are taken along the covering relations in the poset. The first type of Markov chain goes only in one direction, either up or down in the poset (an up chain or down chain). The second type toggles between two adjacent rank levels (an up-and-down chain). We introduce two compatibility concepts between the up-directed transition probabilities (an up rule) and the down-directed (a down rule), and we relate these to compatibility between up-and-down chains. This framework is used to prove a conjecture about a limit shape for a process on Young's lattice. Finally, we settle the questions whether the reverse of an up chain is a down chain for some down rule and whether there exists an up or down chain at all if the rank function is not bounded.

  • Public defence: 2017-05-29 13:15 Kappa, Västerås
    Metri, Prashant G
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    Mathematical Analysis of Forced Convective Flow Due to Stretching Sheet and Instabilities of Natural Convective Flow2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The investigations presented in the thesis are theoretical studies of magnetohydrodynamic flows, heat and mass transfer in Newtonian/non-Newtonian cooling liquids, due to horizontal/vertical stretching sheet. The theoretical studies include the effect of magnetic field, uniform and non-uniform heat source/sink (flow and temperature dependent heat source/sink) effects. The considered problems include flow of viscous fluids in the presence of applied magnetic field and electric field with first order chemical reactions. The viscous incompressible Newtonian fluid flow in porous medium with Darcy-Forchheimmer model, electrically conducting fluid and nanofluid is studied. We introduce innovative techniques for finding solutions of highly nonlinear coupled boundary value problems such as Runge-Kutta method, Perturbation method and Differential Transform Method (DTM).

     

    Chapter 1-2 gives a brief introduction. Chapter 3 focuses on Lie group analysis of MHD flow and heat transfer over a stretching sheet. The effects of viscous dissipation, uniform heat source/sink and MHD on heat transfer are addressed. In Chapter 4-6 we examined the laminar flow, thermocapillary flow of a nanoliquid thin film over an unsteady stretching sheet in presence of MHD and thermal Radiation in different situations. An effective medium theory (EMT) based model is used for the thermal conductivity of the nanoliquid.  Metal and metal oxide nanoparticles are considered in carboxymethyl cellulose (CMC) - water base liquid. In Chapter 7-9 we analyzed, heat and mass transfer in MHD, mixed convection, viscoelastic fluid flow, non-Darcian flow due to stretching sheet in presence of viscous dissipation, non-uniform heat source/sink and porous media have been investigated in different situations.  MHD and viscous dissipation have a significant influence on controlling of the dynamics. 

     

    In Chapter 10 the linear stability of Maxwell fluid-nanofluid flow in a saturated porous layer is examined theoretically when the walls of the porous layers are subjected to time-periodic temperature modulations. A modified Darcy-Maxwell model is used to describe the fluid motion, and the nanofluid model used includes the effects of the Brownian motion. The thermal conductivity and viscosity are considered to be dependent on the nanoparticle volume fraction.

    In Chapter 11 we studied MHD flow in a vertical double passage channel taking into account the presence of the first order chemical reactions. The governing equations are solved by using a regular perturbation technique valid for small values of the Brinkman number and a DTM valid for all values of the Brinkman number.

  • Public defence: 2017-06-08 13:00 Filen, Eskilstuna
    Axelsson, Karin
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Entrepreneurship in a School Setting: Introducing a Business Concept in a Public Context2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Entrepreneurship has during the last decades gained an immense interest in academia, politics and practice. It is argued from politics that more entrepreneurs are necessary for the economic development. In addition, nowadays entrepreneurship is also perceived as a solution to social and societal challenges. This drives a need for entrepreneurial people everywhere in society who can cope with the inconstant and uncertain world of today. As a consequence, there are around the world numerous educational initiatives trying to inspire and fuel an entrepreneurial mind-set. Here, educations of all kind become relevant contexts since they provide an opportunity to affect children, youth’s and adult’s interest and attitudes towards entrepreneurship, and as such give a possibility to reach a vast number of people.

    Sweden is no exception, and in 2009 the Swedish Government launched a ‘Strategy for entrepreneurship in the field of education’ in which entrepreneurship is said to run like a common thread throughout education. The main focus is that self-employment is to become as natural as being an employee. As such the Government took an active stand for implementing entrepreneurship in the school setting on a broad front, from preschool to adult education.

    This development can be seen as part of New Public Management; a development where concepts from the private sector are lent and transferred to the public sector. Thus, when introducing entrepreneurship in the Swedish educational system, this at the same time means introducing a traditional business concept in a public setting. Therefore, the overall aim of this thesis is to increase knowledge of and insights on how a business concept – entrepreneurship – is operationalised and constructed in a public setting.

    When placing entrepreneurship in new societal contexts other questions arise and complexity intensifies. In this qualitative research, the empirical context in focus are schools. It investigates how entrepreneurship is constructed among teachers in their work. But also how this business concept is included in a non-business setting by studying how the entrepreneurship strategy is operationalised in educational practice.

    As such the thesis and its findings contribute to the scientific discussions on societal entrepreneurship and entrepreneurship education, as well as on strategy and strategising in a public context. The research also aspire to serve inspiration, insights and food for thoughts on discussions and reflections on entrepreneurship within the school practice. 

    This compilation thesis include five papers. To be able to fulfil the aim this research use a broad theoretical base and multiple qualitative research methods. The combination of methods include semi-structured interviews, in-depth interview using the stimulated recall method, focus group interviews, participative meetings, observations, document studies, digital questionnaires, written inquiries, analysing texts and critical incidents questionnaires.

  • Public defence: 2017-06-09 13:00 Beta, Västerås
    Arkkukangas, Marina
    Mälardalen University, School of Health, Care and Social Welfare, Health and Welfare.
    Evaluation of the Otago Exercise Programme with or without motivational interviewing: Feasibility, experiences, effects and adherence among older community-dwelling people2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Falls and injuries related to falls are one of the most common health problems among older people and are becoming increasingly more frequent. Regular exercise has been identified as one of the most effective fall-prevention activities for older people; however, awareness of the impact of exercise programmes and adherence to recommended exercise among the elderly population is generally low. Research examining how an exercise programme is administered to and experienced by elderly community-dwelling people is needed.

    The overall aim of this thesis was to investigate the feasibility, experiences and effects of and adherence to the fall-preventive Otago Exercise Programme (OEP) with or without motivational interviewing (MI) among community-dwelling people aged 75 years or older.

    Four studies were performed from October 2012 to May 2016 in a sample of 175 people. Both quantitative and qualitative research methods were used. The methods included the feasibility for conducting a randomized controlled trial (RCT) (I), individual face-to-face interviews (II), an RCT (III) and a prospective cohort study (IV). The intervention was given to two groups. The participants who received OEP with or without MI were compared with a control group that received standard care.

    The feasibility of performing an exercise intervention with or without MI was acceptable from the perspective of the participating physiotherapists. From the perspective of the older participants performing the exercise with behavioural change support, the inclusion of monitored exercises in everyday life and daily routines was important. The participants also expressed experiencing more strength, improved physical functioning and greater hope for an extended active life during old age.

    From the short-term perspective, there were significant improvements within the OEP combined with MI group in terms of physical performance, fall self-efficacy, activity level, and handgrip strength. Improved physical performance and fall self-efficacy were also found within the control group; however, corresponding differences did not occur in the OEP group without MI. There were no significant differences between the study groups after 12 weeks of regular exercise. Adherence to the exercises in the pooled exercise group was 81% at the 12-week follow-up.

    At the 52-week follow-up, the behavioural factors being physically active and obtaining behavioural support in terms of MI had a significant association with adherence to the exercise programme.

    These studies provide some support for the combination of OEP with MI as the addition of MI was valuable for achieving adherence to the exercise programme over time in older community-dwelling people.

     

  • Public defence: 2017-06-15 13:15 Delta, Västerås
    Gusdal, Annelie K
    Mälardalen University, School of Health, Care and Social Welfare, Health and Welfare.
    Family caregiving for persons with heart failure: Perspectives of family caregivers, persons with heart failure and registered nurses2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Heart failure is a growing public health problem associated with significant morbidity and mortality. Family support positively affects outcomes for the person with heart failure while also leading to caregiver burden. Registered nurses have a key role in supporting and meeting the needs of family caregivers.

    The overall aim was to explore the situation and needs of family caregivers to a person with heart failure, and explore requisites and ways of supporting and involving family caregivers in heart failure nursing care.

    Two interview studies, one web survey study and one intervention study were conducted between 2012 and 2017. A total of 22 family caregivers, eight persons with heart failure and 331 registered nurses participated in the studies.

    Family caregivers' daily life was characterized by worry, uncertainty and relational incongruence but salutogenic behaviours restored new strength and motivation to care. Family caregivers experienced that their caregiving was taken for granted by health care professionals. Family caregivers expressed a need for a permanent health care contact and more involvement in the planning and implementation of their near one’s health care together with health care professionals. Registered nurses acknowledged family caregivers’ burden, lack of knowledge and relational incongruence. A registered nurse was suggested as a permanent health care contact to improve continuity and security. Registered nurses neither acknowledged family caregivers as a resource nor their need for involvement. Registered nurses working in primary health care centres, in nurse-led heart failure clinics, with district nurse specialization, with education in cardiac nursing care held the most supportive attitudes toward family involvement in heart failure nursing care. Family health conversations via telephone in nurse-led heart failure clinics were found to successfully support and involve families. The conversations enhanced nurse-family relationship and relations within the family. They also provided registered nurses with new, relevant knowledge and understanding about the family as a whole. Family health conversations via telephone were feasible to both families and registered nurses, although fewer and shorter conversations were preferred by registered nurses.

    This thesis highlights the divergence between family caregivers’ experiences and needs, and registered nurses’ perceptions about family caregivers’ situation and attitudes toward the importance of family involvement. It adds to the knowledge on the importance to acknowledge family caregivers as a resource and to support and involve them in heart failure nursing care. One feasible and successful way is to conduct Family health conversations via telephone in nurse-led heart failure clinics.

  • Public defence: 2017-06-16 09:00 Beta, Västerås
    Stålberg, Anna
    Mälardalen University, School of Health, Care and Social Welfare.
    Facilitating participation: A joint use of an interactive communication tool by children and professionals in healthcare situations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Children’s right to participation in situations that matter to them is stated in law and convention texts and is emphasized by the children themselves in research studies, too. When actively involved, their perspective is visualized. Children’s use of interactive technology has increased considerably during the last decade. The use of applications and web sites are becoming a regular occurrence in paediatric healthcare.

    The overall aim was to develop and test, together with children, an interactive communication tool meant to facilitate young children’s participation in healthcare situations.

    To understand children’s varied perceptions of their involvement in healthcare situations, interviews, drawings and vignettes were used in a phenomenographic approach (I). A participatory design iteratively evaluated evolving prototypes of an application (II). Video observations and hermeneutics captured the meanings of the participation cues that the children demonstrated when they used the application in healthcare situations (III). A quantitative approach was used to identify patterns in the children’s cue use (IV). In total, 114 children in two clinical settings and in a preschool were involved.

    The result showed that the children perceived themselves, their parents and the professionals as actors in a healthcare situation, although all were perceived to act differently (I). The children contributed important information on age-appropriateness, usability and likeability in the iterative evaluating phases that eventually ended up in the application (II). When using the application in healthcare situations, the cues they demonstrated were understood as representing a curious, thoughtful or affirmative meaning (III). Curious cues were demonstrated to the highest extent. The three-year-olds and the children with the least experience of healthcare situations demonstrated the highest numbers of cues (IV).

    Conclusion: when using the application, the children demonstrated a situated participation which was influenced by their perspective of the situation and their inter-inter-action with the application as well as the health professional. The children’s situated participation provided the professionals’ with additional ways of guiding the children based on their perspectives.

  • Public defence: 2017-06-19 13:15 Kappa, Västerås
    Ray, Apala
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. ABB Corporate Research.
    On Pre-deployment Assessment and Security Bootstrapping of Industrial Communication Networks2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The severity of cyber threats towards existing and future industrial systems has resulted in an increase of security awareness in the industrial automation domain. Compared to traditional information systems, industrial communication systems have different performance and reliability requirements. The safety and availability requirements can also sometimes conflict with the system security design of plants. For instance, it is not acceptable to create a secure system that may take up additional time to establish security and as a consequence disrupt the production in plants. Similarly, a system that requires authentication and authorization procedures before an emergency action may not be suitable in industrial plants. On the other hand, lack of security can hamper safety of a plant. Therefore, there is a need for improvement of the security workflow in industrial plants, so that the practical realization of security can be achieved. This includes secure device deployment and secure data communication inside the industrial plants. Furthermore, the industrial plant networks are heterogeneous in terms of hardware, software, and protocols. This complicates security assessment of industrial networks.

     

    In this thesis, the focus is on achieving a secured communication infrastructure for heterogeneous industrial networks. The initial trust establishment is the starting point for enabling a secure communication infrastructure. A framework for the initial trust establishment for industrial devices that can support key management using the existing trust of employees in a plant is proposed. With the help of a proof-of-concept implementation and security analysis, it is shown that the proposed framework is feasible to implement and satisfies the security objectives. After establishing initial trust within industrial devices, assessing heterogeneous security properties based on the network architecture is another focus of this thesis. A model to estimate the security assurance of nodes in a heterogeneous network, where all devices are not having the same level of security mechanisms, is given. Along with cyber security requirements of industrial plants, it is also necessary to consider other important requirements of plants in terms of network performance. In this thesis, identification of an optimized path between two systems in a heterogeneous network in terms of the network performance and the network security is explored. The applicability of this balancing approach has been demonstrated in a specific case of smart grid application where security, network capacity and reachability need to be optimal for successful network operation.