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  • Public defence: 2017-12-15 10:00 Raspen, Eskilstuna
    Asadi, Narges
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Flexibility in assembly systems using product design2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Growing customer demands for product variety, new and rapid technological developments, and the short life cycle of products characterise the current volatile market. To maintain a competitive edge in the market, manufacturing companies need to accommodate flexibility in their assembly systems that are essential parts of the manufacturing systems with respect to cost, time, and creating product variety. Given the importance of establishing flexible assembly systems, the complexity raised by increasing product variety and the value of appropriate product designs to assembly systems highlight the pivotal role of product design in a flexible assembly system. Despite its significance to theory and practice, however, the characteristics of flexibility in an assembly system and its links to product design are still ambiguous and unexplored.

    The objective of this thesis is to expand the current knowledge of flexibility in assembly systems and using product design to support its achievement. To accomplish the objective and by adopting an interactive research approach, five case studies were conducted in the heavy machinery manufacturing industry. A literature review underpins all the case studies comprising one multiple and four single case studies.

    Through its findings, this research defines flexibility in an assembly system, identifies its dimensions, and pinpoints its enablers. Additionally, three requirements of a flexible assembly system for product design are identified: a common assembly sequence, similar assembly interfaces, and common parts. These requirements, if fulfilled in product design across distinct product families, reduce the perceived complexity and support various flexibility dimensions in the assembly system. Moreover, the development of a common assembly sequence and similar assembly interfaces, as the two key requirements of a flexible assembly system for product design, is described.

    Further, based upon developing understanding and knowledge about a flexible assembly system and its requirements for product design, a model and a framework are proposed. The model addresses the role of product design in achieving flexibility in an assembly system. To support the alignment of product design with the key requirements of a flexible assembly system during the product design process, the assembly-oriented framework details the development of these requirements. Through its outcomes, this thesis contributes to the research area of flexible assembly systems and sheds light on its interface with the engineering design field. Moreover, the proposed model and framework aim to assist assembly practitioners and product designers in establishing a flexible assembly system and aligning product design with its key requirements.

  • Public defence: 2017-12-15 13:15 Beta, Västerås
    Sellin, Linda
    Mälardalen University, School of Health, Care and Social Welfare, Health and Welfare.
    A personal-recovery-oriented caring approach to suicidality2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Persons who are subject to care due to suicidal thoughts and/or acts, are in a vulnerable situation, struggling with issues related to life and death as well as experiences of hopelessness and powerlessness. They may also experience themselves as a burden for their relatives. The relatives’ struggle for contributing to the loved person’s survival, can involve experiences of taking responsibility for things that are outside their control. Although research considering how suicidal persons and their relatives can be supported, when the person receives care in a psychiatric inpatient setting is sparse. There is also a need for research to form the basis for mental health nurses to enable caring interventions, with the potential of acknowledging the uniqueness of each individual person and their experiences. This thesis is based on a perspective of recovery as a process, where the persons experience themselves as capable of managing both challenges and possibilities in life and incorporate meaning into it. Experiences of being capable of managing problems in living are vital for this process. Thus, it is necessary to acknowledge the lifeworld as essential for personal recovery.

    The overall aim of this research  was to develop, introduce and evaluate a caring intervention, to support suicidal patients’ recovery and health, and to support patients’ and their relatives’ participation in the caring process. Considering the complexity of such a caring intervention and the importance of recognizing multiple aspects of the phenomenon (i.e., recovery in a suicidal crisis), this research was conducted from a lifeworld perspective based on phenomenological philosophy. Two studies with reflective lifeworld research approach (I, II), a Delphi study (III), and a single case study with QUAL>quan mixed methods research approach (IV) were conducted.

    The developed caring intervention is characterized by “communicative togetherness”. This means that the nurse and the patient together explore how the patient’s recovery can be supported, as a way for the patient to reconnect with self and important others, and thereby being strengthened when challenged by problems in living. It was also concluded that it is more appropriate to acknowledge this as a caring approach, rather than describe it as a specific caring intervention. The final description of the findings comprise a preliminary guide to a personal-recovery-oriented caring approach to suicidality (PROCATS). This description highlights six core aspects of the caring approach. The overall aim of the PROCATS is to support suicidal patients’ recovery and health processes, even at the very edge of life. Although the findings indicate that the caring approach has potential to support suicidal patients’ recovery as well as support their relatives’ participation, there is a need for further evaluation of the PROCATS in a wider context.

  • Public defence: 2017-12-19 09:00 Kappa, Västerås
    Becker, Matthias
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Consolidating Automotive Real-Time Applications on Many-Core Platforms2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Automotive systems have transitioned from basic transportation utilities to sophisticated systems. The rapid increase in functionality comes along with a steep increase in software complexity. This manifests itself in a surge of the number of functionalities as well as the complexity of existing functions. To cope with this transition, current trends shift away from today’s distributed architectures towards integrated architectures, where previously distributed functionality is consolidated on fewer, more powerful, computers. This can ease the integration process, reduce the hardware complexity, and ultimately save costs.

    One promising hardware platform for these powerful embedded computers is the many-core processor. A many-core processor hosts a vast number of compute cores, that are partitioned on tiles which are connected by a Network-on-Chip. These natural partitions can provide exclusive execution spaces for different applications, since most resources are not shared among them. Hence, natural building blocks towards temporally and spatially separated execution spaces exist as a result of the hardware architecture.

    Additionally to the traditional task local deadlines, automotive applications are often subject to timing constraints on the data propagation through a chain of semantically related tasks. Such requirements pose challenges to the system designer as they are only able to verify them after the system synthesis (i.e. very late in the design process).

    In this thesis, we present methods that transform complex timing constraints on the data propagation delay to precedence constraints between individual jobs. An execution framework for the cluster of the many-core is proposed that allows access to cluster external memory while it avoids contention on shared resources by design. A partitioning and configuration of the Network-on-Chip provides isolation between the different applications and reduces the access time from the clusters to external memory. Moreover, methods that facilitate the verification of data propagation delays in each development step are provided. 

  • Public defence: 2017-12-19 13:30 Kappa, Västerås
    Afshar, Sara
    Mälardalen University, School of Innovation, Design and Engineering.
    Lock-Based Resource Sharing for Real-Time Multiprocessors2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Embedded systems are widely used in the industry and are typically resource constrained, i.e., resources such as processors, I/O devices, shared buffers or shared memory might be limited in the system. Hence, techniques that can enable an efficient usage of processor bandwidths in such systems are of great importance. Locked-based resource sharing protocols are proposed as a solution to overcome resource limitation by allowing the available resources in the system to be safely shared. In recent years, due to a dramatic enhancement in the functionality of systems, a shift from single-core processors to multi-core processors has become inevitable from an industrial perspective to tackle the raised challenges due to increased system complexity. However, the resource sharing protocols are not fully mature for multi-core processors. The two classical multi-core processor resource sharing protocols, spin-based and suspension-based protocols, although providing mutually exclusive access to resources, can introduce long blocking delays to tasks, which may be unacceptable for many industrial applications. In this thesis we enhance the performance of resource sharing protocols for partitioned scheduling, which is the de-facto scheduling standard for industrial real-time multi-core processor systems such as in AUTOSAR, in terms of timing and memory requirements.

     

    A new scheduling approach uses a resource efficient hybrid approach combining both partitioned and global scheduling where the partitioned scheduling is used to schedule the major number of tasks in the system. In such a scheduling approach applications with critical task sets use partitioned scheduling to achieve higher level of predictability. Then the unused bandwidth on each core that is remained from partitioning is used to schedule less critical task sets using global scheduling to achieve higher system utilization. These scheduling schema however lacks a proper resource sharing protocol since the existing protocols designed for partitioned and global scheduling cannot be directly applied due to the complex hybrid structure of these scheduling frameworks. In this thesis we propose a resource sharing solution for such a complex structure. Further, we provide the blocking bounds incurred to tasks under the proposed protocols and enhance the schedulability analysis, which is an essential requirement for real-time systems, with the provided blocking bounds.

  • Public defence: 2017-12-20 10:00 Verktyget, Eskilstuna
    Ahlskog, Mats
    Mälardalen University, School of Innovation, Design and Engineering. Eskilstuna.
    The fuzzy front end of manufacturing technology development: Exploring the link between the known and the unknown2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    It is well known that a way of competing on a global market is through the introduction of new manufacturing technologies in the production system that can improve product quality as well as contribute to reducing manufacturing time, reduced product price and in the end increased profits. Manufacturing companies that develop and introduce new manufacturing technologies can differentiate themselves from others and thus achieve increased competitiveness.

    The fuzzy front end of manufacturing technology development is characterized by a high degree of technology uncertainty and challenges due to the lack of access to relevant knowledge, lack of a structured development process, and enough resources that are working with development of new manufacturing technologies.

    In the literature only a few empirical studies that explore the fuzzy front end of manufacturing technology development can be found. Prior research highlights that little is actually known about what should be done in the fuzzy front end of manufacturing technology development projects, and thus more research is needed. Supporting the fuzzy front end of manufacturing technology development is important to facilitate a successful introduction of new manufacturing technologies, fast time-to-volume and long-term production system development.

    Based on the above-mentioned importance of developing new manufacturing technology, the objective of the research presented in this thesis is to explore the fuzzy front end of manufacturing technology development. In order to fulfil the objective, empirical data were collected from five case studies conducted in the manufacturing industry. During the empirical studies four important parts were studied: organising, knowledge development, collaboration and the development process.

    The main findings revealed that development of new manufacturing technology is often conducted in collaboration with external partners and many ad hoc decisions are taken due to lack of a predefined development process for the fuzzy front end of manufacturing technology development. In addition, in the fuzzy front end access to relevant manufacturing knowledge is important and knowledge needs to be developed in order to reduce technology uncertainty.

    In order to support the fuzzy front end of manufacturing technology development projects, a supporting framework has been developed. The proposed framework is an elaboration of results from the research questions addressed and can be used as a guideline to overcome the challenges observed in the fuzzy front end of manufacturing technology development projects. The framework is built on two important dimensions for innovations, degree of technology uncertainty and degree of novelty. The critical factors identified in the analysis are embedded in the proposed framework as central parts in the fuzzy front end of manufacturing technology development.

  • Public defence: 2018-01-12 10:15 Gamma, Västerås
    Bucaioni, Alessio
    Mälardalen University, School of Innovation, Design and Engineering.
    A Model-driven Development Approach with Temporal Awareness for Vehicular Embedded Systems2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Considering the ubiquitousness of software in modern vehicles, its increased value and development cost, an efficient software development became of paramount importance for the vehicular domain. It has been identified that early verification of non functional properties of  vehicular embedded software such as, timing, reliability and safety, is crucial to efficiency. However, early verification of non functional properties is hard to achieve with traditional software development approaches due to the abstraction and the lack of automation of these methodologies.

     

    This doctoral thesis aims at improving efficiency in vehicular embedded software development by minimising the need for late, expensive and time consuming software modifications with early design changes, identified through timing verification, which usually are cheaper and faster. To this end, we introduce a novel model-driven approach which exploits the interplay of two automotive-specific modelling languages for the representation of functional and execution models and defines a suite of model transformations for their automatic integration.

     

    Starting from a functional model (expressed by means of EAST-ADL), all the execution models (expressed by means of the Rubus Component Model) entailing unique timing configurations are derived. Schedulability analysis selects the set of the feasible execution models with respect to specified timing requirements. Eventually, a reference to the selected execution models along with their analysis results is automatically created in the related functional model to allow the engineer to investigate them.

     

    The main scientific contributions of this doctoral thesis are i) a metamodel definition for the Rubus Component Model, ii) an automatic mechanism for the generation of Rubus models from EAST-ADL, iii) an automatic mechanism for the selection and back-propagation of the analysis results and related Rubus models to design level and iv) a compact notation for visualising the selected Rubus models by means of a single execution model.

  • Public defence: 2018-01-12 13:00 Delta, Västerås
    Zhou, Jiale
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    An Ontological Approach to Safety Analysis of Safety-Critical Systems2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Safety-critical systems (SCSs) have become an intrinsic part of human dailylife in multiple domains, such as automotive, avionics, and rail industries. Suchsystems are not only required to implement the functionality they should provide, but also have to satisfy a set of safety requirements in order to ensure themitigation of hazardous consequences.

    It is fundamental that safety requirements are defined based on the resultsissued from safety analysis. Various studies have asserted that most significant flaws in the safety requirements are related to the omission of hazards andcauses associated with the identified hazards in early stages of SCSs development. The main drawbacks of the current practice applied in safety analysis,lie in that:

    due to the lack of a common understanding of the hazard concept,the hazards and their causes are typically identified in accordance to theintuition and experience of the analysts and,

    analysts are inclined to identify generic causes for a certain hazarddescription, for example, “Design flaw, Coding error, and Human error”and,

    there is an essential need to formalize the experience of the analystsin a structured way, in order to save effort and,

    since traditional safety analysis techniques are usually based on wellknown system behaviors represented by models, such as automata andsequence diagrams, a new approach is needed when such behavioralmodels are not available.

    These considerations motivate us to formulate the following general researchquestion: How can safety analysis, within the context of safety-critical systems, be conducted to reduce the omission of potential hazards and their causes inearly stages of the system development life-cycle?

    In this thesis, we propose an ontological approach to safety analysis forsafety-critical systems, which mainly consists of four pieces of work:

    we propose an ontological interpretation of the hazard concept, calledthe Hazard Ontology (HO), to define an explicit representation of theknowledge of hazards and their relations with the system under analysisand existing environment and,

    we propose an approach to identify hazards in early stages of thesafety-critical systems development, based on the HO and,

    we propose an approach to identify the causes associated with a certain hazard description for safety-critical systems, based on the HO and,

    we propose a heuristic approach to safety requirements elicitation,based on the HO.

  • Public defence: 2018-01-19 13:15 Zeta, Västerås
    Lindvall, Jannika
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    Critical features and impacts of mathematics teacher professional development programs: Comparing and characterizing programs implemented at scale2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim of this thesis is to contribute to the knowledge base on conceptualizations and impacts of teacher professional development (PD) programs. This is done by studying the case of two large-scale teacher PD programs. The first was mandatory for all public elementary school mathematics teachers in a larger Swedish municipality, and the second has been completed by 76% of all elementary school mathematics teachers in Sweden. In the municipality, and during the time frame in which this study was conducted, it was possible to make a comparison between teachers participating in different programs. Data on the programs’ impacts on teachers, instruction, and student achievement were gathered both immediately and one year after the teachers’ participation in one of them. In other words, the context of the study created an opportunity to respond to recent calls for studies that (a) examine the impacts of PD programs implemented on a larger scale, (b) adhere to PD programs’ impacts on teachers, instruction, and student achievement, (c) examine the sustainability of PD programs’ impacts, and (d) attend to variations within and between PD programs’ impacts. The results show that the studied programs are highly similar if characterized according to established research frameworks on what constitutes critical features of teacher PD. At the same time, they demonstrate different impacts, both between the programs and within them. These results suggested an elaboration of two of the five critical features of teacher PD: Content Focus and Coherence. Through the development and application of a more finely grained tool to characterize the programs’ Content Focus, differences between their characteristics were detected. Together with a systematic review of the PD research literature on Coherence, these results formed a basis for discussing plausible reasons for the difference in the programs’ impacts as well as elaborating on the critical features of Content Focus and Coherence. In summary, the thesis contributes: (a) empirical results in relation to large-scale teacher PD programs’ impacts; (b) methodological results in the form of tools for characterizing PD programs’ Content Focus and Coherence; and (c) theoretical results, as it examines established frameworks for characterizing teacher PD programs by using them in practice and, in light of the results, also suggests an elaboration of them.