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  • Disputas: 2020-06-05 10:00 A1-068/Digital, Eskilstuna
    Osterman, Christer
    Mälardalens högskola, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Defining Gaps in Lean: Increasing the ability to solve problems in a production system2020Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In recent decades, Lean has grown in popularity and has spread around the world. Despite its popularity, many companies and organizations report difficulties, and the success rate is low. Lean is presented as a simple, holistic concept. Lean has been studied by many researchers from different perspectives. This has resulted in numerous views of Lean. Not all views are not equally well defined. A few have gaps. Three of these are the focus of this research. They are the Value – Value-add – Waste assumption (V-VA-W) resulting in challenges understanding process problems, the Jargon problem (JP) resulting in challenges understanding Lean practice and actually solving problems, and the System problem (SP) resulting in challenges developing solutions without negative effects for other parts of the system.

    Practices that developed into Lean evolved over many years, primarily at Toyota. Over time the experience of solving a massive number of small problems resulted in rules of thumb, which, much later, were codified as Lean principles. The ability to understand and solve problems at the group level of a process, therefore, serves as a measure of Lean gaps. The purpose of this research is to provide a better definition of the gaps in order to increase problem-solving ability at the group level of a process. In addition, a better definition of the gaps provides researchers with a deeper understanding of Lean.

    The thesis is based on four multiple case studies resulting in five papers. Each study provides a piece of the puzzle. The V-VA-W assumption can be better defined by including changeability in solutions, resulting in lower process costs when conditions change and evaluating the complexity of a process before defining waste. JP can be better defined through a balance of contextual adaptation of solutions while retaining the overall purpose of the production system and through synchronizing the understanding of Lean in the organization based on method utility. Finally, SP is defined through balancing requirements of a particular solution against how it affects the entire system, and also considering the application order of system elements as a consequence of a contextually dependent starting point. In total, a better understanding of the nature of problems and solutions together with an understanding of how the system interrelates creates the right conditions for a better understanding of the concept of Lean in general and, hopefully, a higher Lean integration.

    Fulltekst (pdf)
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  • Disputas: 2020-06-10 13:00 Sal Beta, Västerås
    Värnild, Astrid
    Mälardalens högskola, Akademin för hälsa, vård och välfärd, Hälsa och välfärd.
    Seriously injured road users in rural and urban road traffic in a Swedish region - a Vision Zero perspective2020Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Globally more than 50 million people are injured in road traffic every year. The incidence of road injuries is increasing while that of fatalities is decreasing. Road safety measures are being implemented in many countries to reduce the effects on public health. In highly motorized countries, the process is often managed by quantitative targets. Sweden has a target for 2020 based on Vision Zero: that no-one should be killed or seriously injured in road traffic. In Vision Zero, pedestrians in single crashes are not defined as road users, even when they move in the same areas as road users with vehicles. In this thesis the road space (pavements, tracks and roads) defines the road user.

    The aim of the thesis is to study the development of serious injuries in rural and urban areas during a period when Vision Zero was being implemented through government efforts to direct the process in Sweden. The thesis adopts a regional perspective. Three of the four studies in the thesis are cross-sectional studies with data from Region Västmanland during twelve to fifteen years, 2003–2017. Data are also based on analyses of ten regional infrastructure plans in Sweden for the period 2014–2025.

    On national roads in the region, the incidence of serious injuries decreased for car occupants, but on regional roads it increased. In urban areas the incidence for unprotected road users doubled on roads and more than doubled on tracks and pavements where the greatest number of unprotected road users are seriously injured. One factor in the increased incidence is the growing number of elderly people in the population caused by the large generation born in the 1940s and a lengthening lifespan. From 2012 the probability of being seriously injured increased for cyclists and pedestrians 80 years and older, and from 2015 for the group 65 years and older.

    In urban areas during the period, there was a shift in serious injuries for pedestrians and cyclists from less head injuries to more injuries in lower extremities. The probability of receiving serious injuries to the lower extremities increased fourfold from the age of 50 for both pedestrians and cyclists, but for cyclists the probability increased with age.

    For pedestrians, pavements and tracks were associated with decreased probability of all injuries except for head injuries, but for cyclists this decrease is only seen for the most severe injuries. For pedestrians, the probability of getting injuries in more than one bodily region decreased on Vision Zero roads.

    Prioritized investments in regional plans are mostly justified by accessibility and increased walking and cycling, and only more sparsely by road safety. This reflects an imbalance in the government’s clarifications of the transport goals.

    In directives for regional planning and in support of the objectives of Agenda 2030, the government has argued for more active mobility. There is a need to include pedestrian falls in the category of single crashes in the work with Vision Zero. Increased walking and cycling justifies more road safety measures especially in urban areas in order to achieve the targets of Vision Zero. To achieve Vision Zero it is important that the concerned road authorities and regions are committed to the goals and fulfil their tasks. More active mobility in combination with an increased number of older people is a challenge for municipalities as road authorities in urban areas.

    Fulltekst (pdf)
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  • Disputas: 2020-06-12 10:00 Västerås Campus (+ Online/Zoom), Västerås
    Frasheri, Mirgita
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Modelling and Control of the Collaborative Behavior of Adaptive Autonomous Agents2020Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Research on autonomous agents and vehicles has gained momentum in the past years, which is reflected in the extensive body of literature and the investment of big players of the industry in the development of products such as self-driving cars. Additionally, these systems are envisioned to continuously communicate and cooperate with one another in order to adapt to dynamic circumstances and unforeseeable events, and as a result will they fulfil their goals even more efficiently.The facilitation of such dynamic collaboration and the modelling of interactions between different actors (software agents, humans) remains an open challenge.This thesis tackles the problem of enabling dynamic collaboration by investigating the automated adjustment of autonomy of different agents, called Adaptive Autonomy (AA). An agent, in this context, is a software able to process and react to sensory inputs in the environment in which it is situated in, and is additionally capable of autonomous actions. In this work, the collaborative adaptive autonomous behaviour of agents is shaped by their willingness to interact with other agents, that captures the disposition of an agent to give and ask for help, based on different factors that represent the agent's state and its interests.The AA approach to collaboration is used in two different domains: (i) the hunting mobile search problem, and (ii) the coverage problem of mobile wireless sensor networks. In both cases, the proposed approach is compared to state-of-art methods.Furthermore, the thesis contributes on a conceptual level by combining and integrating the AA approach -- which is purely distributed -- with a high-level mission planner, in order to exploit the ability of dealing with local and contingent problems through the AA approach, while minimising the requests for a re-plan to the mission planner.

    Fulltekst (pdf)
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  • Disputas: 2020-06-15 13:30 Delta (+ Online/Zoom), Västerås
    Marković, Filip
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Preemption-Delay Aware Schedulability Analysis of Real-Time Systems2020Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Schedulability analysis of real-time systems under preemptive scheduling may often lead to false-negative results, deeming a schedulable taskset being unschedulable. This is the case due to the inherent over-approximation of many time-related parameters such as task execution time, system delays, etc., but also, in the context of preemptive scheduling, a significant over-approximation arises from accounting for task preemptions and corresponding preemption-related delays. To reduce false-negative schedulability results, it is highly important to as accurately as possible approximate preemption-related delays. Also, it is important to obtain safe approximations, which means that compared to the approximated delay, no higher corresponding delay can occur at runtime since such case may lead to false-positive schedulability results that can critically impact the analysed system. Therefore, the overall goal of this thesis is:

    To improve the accuracy of schedulability analyses to identify schedulable tasksets in real-time systems under fixed-priority preemptive scheduling, by accounting for tight and safe approximations of preemption-related delays.

    We contribute to the domain of timing analysis for single-core real-time systems under preemptive scheduling by proposing two novel cache-aware schedulability analyses: one for fully-preemptive tasks, and one for tasks with fixed preemption points. Also, we propose a novel method for deriving safe and tight upper bounds on cache-related preemption delay of tasks with fixed preemption points. Finally, we contribute to the domain of multi-core partitioned hard real-time systems by proposing a novel partitioning criterion for worst-fit decreasing partitioning, and by investigating the effectiveness of different partitioning strategies to provide task allocation which does not jeopardize the schedulability of a taskset in the context of preemptive~scheduling.