| 1. |
- Kinene, Alan, 1991-
(författare)
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Models for the Procurement of Subsidized Air Services : Conventional Aircraft and the Adoption of Electric Aircraft
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In liberalized air transportation markets, governments often adopt subsidy schemes through which they ensure air services along routes that are deemed commercially non-viable but economically and socially essential. The objective of these subsidized air service routes is to ensure a minimum level of services to outlying communities or remote regions that are difficult to access—by other modes of transportation—from the capital, other main cities or a hub airport yet can not be served commercially due to thin demand. Through these subsidy schemes, transportation authorities offer compensation—usually in form of subsidies—to airlines in exchange for air services. Subsidized air services face two main criticisms: their misuse, for example selecting routes that may sufficiently be served by other modes of transportation; and the excessive subsidies spent by transportation authorities. Addressing these criticisms is key for the planning of socially and economically efficient subsidized air service networks. However, decision support models to address these criticisms are scant in both literature and current practice. Furthermore, past studies have naturally focused on models specific to the existing aircraft technology (i.e, conventional aircraft) with no attention towards electric aircraft yet, (1) their uptake appears faster today than predicted, and (2) they are expected to be more environmentally friendly with zero CO2 emissions during operation) and cheaper to operate than conventional aircraft.This thesis develops decision support models using the conventional aircraft as well as electric aircraft. Specifically, the thesis contributes with optimization models that can be used by transportation authorities to select the routes to subsidize, to set appropriate level of service requirements that should be met by the airlines (while either minimizing the subsidies or total social cost), and to strategically plan for the adoption of electric aircraft on subsidized routes. The usefulness of the models is demonstrated through applications to the subsidized air service network in Sweden, and this gives three main insights. First, transportation authorities can use an optimization model to improve accessibility of outlying regions to given destinations and at lower subsidy cost. Second, having a requirement on the maximum airfare but not the minimum number of flights provides an appropriate set of service requirements that should be met by the airlines. Third, leveraging the many currently under-utilized regional airports during the adoption of electric aircraft has accessibility and infrastructure-investment benefits; however, the isolated adoption of a homogeneous fleet of electric aircraft with limited seat capacity, slow speed and short range capabilities is not sufficient to serve remote regions. In the short run—at least until the the battery technology develops further—a hybrid network consisting of both these electric aircraft and the larger, faster and longer range conventional aircraft can be leveraged to provide a better services to the people.
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| 2. |
- Pettersson, Oskar, 1984-
(författare)
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Towards a Mobile Learning Software Ecosystem
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ability to carry communication services around, combined with the ubiquitous presence of computing technology, affects everything we do from how we pay for things to how we expect to interact with public institutions such as schools. There are now plenty of systems that convey education by utilizing mobile devices. As an extension of technology moving towards ubiquity, there are efforts aiming to bring this to an educational use as well. Efforts in this direction are channelized in the field of mobile learning. The speed of technological development, and the possibilities it brings introduces a large number of challenges when implemented in educational settings. These challenges can be related to for example pedagogical aspects, tools, implementations and organizations. Recent developments including the notions of learning ecosystems, learning landscapes and organizations suggest that the domain of mobile learning can be negatively affected from the lack of a systematic reuse approach. This thesis pursues these challenges by investigating how systematic reuse can be promoted in mobile learning systems. A collection of five peer-reviewed publications that elaborates on the different stages of the research process pursuing the main research question forms the core of this thesis. This research process includes a survey stage, elaborating on different aspects related to reuse and mobile learning, an analysis stage that resulted in a descriptive model and several additional domain models; and finally a stage where the descriptive model is refined into a reference model for mobile learning ecosystems. The outcomes of these activities and the analysis of these results provide some fundamental building blocks regarding how to approach the challenge of reuse in mobile learning systems. The proposed reference model can be considered as the first step towards the creation of a common vocabulary that can be used to compare Software Ecosystems within the domain of mobile learning.
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| 3. |
- Abramian, David, 1992-
(författare)
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Modern multimodal methods in brain MRI
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Magnetic resonance imaging (MRI) is one of the pillars of modern medical imaging, providing a non-invasive means to generate 3D images of the body with high soft-tissue contrast. Furthermore, the possibilities afforded by the design of MRI sequences enable the signal to be sensitized to a multitude of physiological tissue properties, resulting in a wide variety of distinct MRI modalities for clinical and research use. This thesis presents a number of advanced brain MRI applications, which fulfill, to differing extents, two complementary aims. On the one hand, they explore the benefits of a multimodal approach to MRI, combining structural, functional and diffusion MRI, in a variety of contexts. On the other, they emphasize the use of advanced mathematical and computational tools in the analysis of MRI data, such as deep learning, Bayesian statistics, and graph signal processing. Paper I introduces an anatomically-adapted extension to previous work in Bayesian spatial priors for functional MRI data, where anatomical information is introduced from a T1-weighted image to compensate for the low anatomical contrast of functional MRI data. It has been observed that the spatial correlation structure of the BOLD signal in brain white matter follows the orientation of the underlying axonal fibers. Paper II argues about the implications of this fact on the ideal shape of spatial filters for the analysis of white matter functional MRI data. By using axonal orientation information extracted from diffusion MRI, and leveraging the possibilities afforded by graph signal processing, a graph-based description of the white matter structure is introduced, which, in turn, enables the definition of spatial filters whose shape is adapted to the underlying axonal structure, and demonstrates the increased detection power resulting from their use. One of the main clinical applications of functional MRI is functional localization of the eloquent areas of the brain prior to brain surgery. This practice is widespread for various invasive surgeries, but is less common for stereotactic radiosurgery (SRS), a non-invasive surgical procedure wherein tissue is ablated by concentrating several beams of high-energy radiation. Paper III describes an analysis and processing pipeline for functional MRI data that enables its use for functional localization and delineation of organs-at-risk for Elekta GammaKnife SRS procedures. Paper IV presents a deep learning model for super-resolution of diffusion MRI fiber ODFs, which outperforms standard interpolation methods in estimating local axonal fiber orientations in white matter. Finally, Paper V demonstrates that some popular methods for anonymizing facial data in structural MRI volumes can be partially reversed by applying generative deep learning models, highlighting one way in which the enormous power of deep learning models can potentially be put to use for harmful purposes.
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| 4. |
- Johansson, Helena, 1971-
(författare)
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Mathematical Reasoning : In physics and real-life context
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is a compilation of four papers in which mathematical reasoning is examined in various contexts, in which mathematics is an integral part. It is known from previous studies that a focus on rote learning and procedural mathematical reasoning hamper students’ learning of mathematics. The aims of this thesis are to explore how mathematical reasoning affects upper secondary students’ possibilities to master the physics curricula, and how real-life contexts in mathematics affect students’ mathematical reasoning. This is done by analysing the mathematical reasoning requirements in Swedish national physics tests; as well as by examining how mathematical reasoning affects students’ success on the tests/tasks. Furthermore, the possible effect of the presence of real-life contexts in Swedish national mathematics tasks on students’ success is explored; as well as if the effect differs when account is taken to mathematical reasoning requirements. The framework that is used for categorising mathematical reasoning, distinguishes between imitative and creative mathematical reasoning, where the latter, in particular, involves reasoning based on intrinsic properties. Data consisted of ten Swedish national physics tests for upper secondary school, with additional student data for eight of the tests; and six Swedish national mathematics tests for upper secondary school, with additional student data. Both qualitative and quantitative methods were used in the analyses. The qualitative analysis consisted of structured comparisons between representative student solutions and the students’ educational history. Furthermore, various descriptive statistics and significance tests were used. The main results are that a majority of the physics tasks require mathematical reasoning, and particularly that creative mathematical reasoning is required to fully master the physics curricula. Moreover, the ability to reason mathematically creatively seems to have a positive effect on students’ success on physics tasks. The results indicate additionally, that there is an advantage of the presence of real-life context in mathematics tasks when creative mathematical reasoning is required. This advantage seems to be particularly notable for students with lower grades.
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| 5. |
- Sebelius, Sofia, 1980-
(författare)
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Idrottsläraryrkets strävan efter mål och status
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish school system has undergone a significant change and development during the last 180 years. The Physical Education Teacher Education (PETE) has made its own development journey, from training gymnastics directors with a particular focus on floor gymnastics and fencing, to becoming a university education with its foundation in sports science.Despite the significant changes in the school's governance and the development of PETE, the same development does not seem to have taken place for the professional practice of Physical Education (PE) teachers. The PE teachers seem to have difficulties formulating what the knowledge objective of the PE subject is. There also seem to be difficulties in formulating how learning in the PE subject should take place. A certain reproduction of traditional values takes place, and the PE teaching profession is described and experienced as marginalised. Based on this, the dissertation's aim is to create an understanding of the PE teachers’ pursuit of purpose and status and what that pursuit entails. To achieve this aim, two studies have been conducted. Based on the perspective that PE teachers function as street-level bureaucrats, the first study aims to understand what governs their professional practice and how they manage it. The aim of the second study is to understand which continuities exist in the language used about the PE teaching profession and what it means for the professional claims of the PE teaching profession.By analysing the language within and about the PE teacher profession, the dissertation creates an understanding of PE teachers' pursuit of purpose and status and what that pursuit entails. The thesis shows that PE teachers in their professional practice are Problem Solvers, Comfort Creators and Organisers. It further identifies continuities in the language about the PE teacher profession gathered within the themes of Strength, Liveliness and Status. Finally, the dissertation describes how the PE teacher profession uses social closure in its professional claim.
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