| 1. |
- Broman, David, 1977-
(författare)
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Safety, Security, and Semantic Aspects of Equation-Based Object-Oriented Languages and Environments
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the last two decades, the interest for computer aided modeling and simulation of complex physical systems has witnessed a significant growth. The recent possibility to create acausal models, using components from different domains (e.g., electrical, mechanical, and hydraulic) enables new opportunities. Modelica is one of the most prominent equation-based object-oriented (EOO) languages that support such capabilities, including the ability to simulate both continuous- and discrete-time models, as well as mixed hybrid models. However, there are still many remaining challenges when it comes to language safety and simulation security. The problem area concerns detecting modeling errors at an early stage, so that faults can be isolated and resolved. Furthermore, to give guarantees for the absence of faults in models, the need for precise language specifications is vital, both regarding type systems and dynamic semantics.This thesis includes five papers related to these topics. The first paper describes the informal concept of types in the Modelica language, and proposes a new concrete syntax for more precise type definitions. The second paper provides a new approach for detecting over- and under-constrained systems of equations in EOO languages, based on a concept called structural constraint delta. That approach makes use of type checking and a type inference algorithm. The third paper outlines a strategy for using abstract syntax as a middle-way between a formal and informal language specification. The fourth paper suggests and evaluates an approach for secure distributed co-simulation over wide area networks. The final paper outlines a new formal operational semantics for describing physical connections, which is based on the untyped lambda calculus. A kernel language is defined, in which real physical models are constructed and simulated.
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| 2. |
- Drobin, Kimi
(författare)
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Antibody-based bead arrays for high-throughput protein profiling in human plasma and serum
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Affinity-based proteomics utilizes affinity binders to detect target proteins in a large-scale manner. This thesis describes a high-throughput method, which enables the search for biomarker candidates in human plasma and serum. A highly multiplexed antibody-based suspension bead array is created by coupling antibodies generated in the Human Protein Atlas project to color-coded beads. The beads are combined for parallel analysis of up to 384 analytes in patient and control samples. This provides data to compare protein levels from the different groups.In paper I osteoporosis patients are compared to healthy individuals to find disease-linked proteins. An untargeted discovery screening was conducted using 4608 antibodies in 16 cases and 6 controls. This revealed 72 unique proteins, which appeared differentially abundant. A validation screening of 91 cases and 89 controls confirmed that the protein autocrine motility factor receptor (AMFR) is decreased in the osteoporosis patients.Paper II investigates the risk proteome of inflammatory bowel disease (IBD). Antibodies targeting 209 proteins corresponding to 163 IBD genetic risk loci were selected. To find proteins related to IBD or its subgroups, sera from 49 patients with Crohn’s disease, 51 with ulcerative colitis and 50 matched controls were analyzed. From these targeted assays, the known inflammation-related marker serum amyloid protein A (SAA) was shown to be elevated in the IBD cases. In addition, the protein laccase (multi-copper oxidoreductase) domain containing 1 (LACC1) was found to be decreased in the IBD subjects.In conclusion, assays using affinity-based bead arrays were developed and applied to screen human plasma and serum samples in two disease contexts. Untargeted and targeted screening strategies were applied to discover disease-associated proteins. Upon further validation, these potential biomarker candidates could be valuable in future disease studies.
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| 3. |
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| 4. |
- Hertz, Erik, 1956-
(författare)
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Parabolic Synthesis
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many consumer products, such as within the computer areas, computer graphics, digital signal processing, communication systems, robotics, navigation, astrophysics, fluid physics, etc. are searching for high computational performance as a consequence of increasingly more advanced algorithms in these applications. Until recently the down scaling of the hardware technology has been able to fulfill these higher demands from the more advanced algorithms with higher clock rates on the chips. This that the development of hardware technology performance has stagnated has moved the interest more over to implementation of algorithms in hardware. Especially within wireless communication the desire for higher transmission rates has increased the interest for algorithm implementation methodologies. The scope of this thesis is mainly on the developed methodology of parabolic synthesis. The parabolic synthesis methodology is a methodology for implementing approximations of unary functions in hardware. The methodology is described with the criteria's that have to be fulfilled to perform an approximation on a unary function. The hardware architecture of the methodology is described and to this a special hardware that performs the squaring operation. The outcome of the presented research is a novel methodology for implementing approximations of unary functions such as trigonometric functions, logarithmic functions, as well as square root and division functions etc. The architecture of the processing part automatically gives a high degree of parallelism. The methodology is founded on operations that are simple to implement in hardware such as addition, shifts, multiplication, contributes to that the implementation in hardware is simple to perform. The hardware architecture is characterized by a high degree of parallelism that gives a short critical path and fast computation. The structure of the methodology will also assure an area efficient hardware implementation.
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| 5. |
- Markkanen, Peter, 1964-
(författare)
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"Tekniken utan en lärare är ingenting" : En studie om användande av teknik i geometriundervisning
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Målet med denna avhandling är att bidra med kunskap om hur digital teknik kan bidra till att utveckla matematikundervisning. I studien riktades intresset mot undervisning i tredimensionell geometri som skedde med stöd av interaktiva skrivtavlor. Syftet varatt studera hur läraren utnyttjar tekniken för att skapa matematiska situationer vilka kan möjliggöra lärande. Studien har en etnografisk inriktning där forskaren under fem veckor följdeen lärares teknikunderstödda undervisning i en klass i årskurs 9. Det empiriska materialet samlades in genom videounderstödd observation, intervju med läraren, fokusgruppsintervjuer med elever samt elevtester. Detta materialanalyserades med fokus på desätt på vilka läraren utnyttjar tekniken för att lyfta fram och arbetamed det matematiska innehållet. Resultatet visar att läraren utnyttjar flertalet strategier som tekniken erbjuder för att representera det matematiska innehållet och med teknikens hjälp växla mellan olika representationsformer, t.ex. genom att bearbeta, flytta och klona geometriska figurer. Läraren är överlag positiv till användande av teknik i matematikundervisningen, och de fördelar med tekniken som hon lyfter fram är att den hjälper och understödjerhenne utifrån de behov som uppstår i undervisningen och ger henne fler verktyg att belysa sådant som en del elever kan ha svårt att få syn på. Resultatet visar även att det fordras mycket arbete av läraren att sätta sig in i teknikens möjligheter och anpassa dessa till den egna undervisningen. Även eleverna är positiva till undervisning som sker med stöd av teknik då de menar att det hjälper dem att skapa sig en förståelse för tredimensionell geometri. Detta stärks av resultaten på det uppföljandetest som genomfördes efter arbetsområdet vilket visar att eleverna på ett påtagligt sätt utvecklat sin förståelse för geometriska begrepp.
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| 6. |
- Nilsson, Anders, 1973-
(författare)
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Dimensions and projections
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns dimensions and projections of sets that could be described as fractals. The background is applied problems regarding analysis of human tissue. One way to characterize such complicated structures is to estimate the dimension. The existence of different types of dimensions makes it important to know about their properties and relations to each other. Furthermore, since medical images often are constructed by x-ray, it is natural to study projections.This thesis consists of an introduction and a summary, followed by three papers.Paper I, Anders Nilsson, Dimensions and Projections: An Overview and Relevant Examples, 2006. Manuscript.Paper II, Anders Nilsson and Peter Wingren, Homogeneity and Non-coincidence of Hausdorff- and Box Dimensions for Subsets of ℝn, 2006. Submitted.Paper III, Anders Nilsson and Fredrik Georgsson, Projective Properties of Fractal Sets, 2006. To be published in Chaos, Solitons and Fractals.The first paper is an overview of dimensions and projections, together with illustrative examples constructed by the author. Some of the most frequently used types of dimensions are defined, i.e. Hausdorff dimension, lower and upper box dimension, and packing dimension. Some of their properties are shown, and how they are related to each other. Furthermore, theoretical results concerning projections are presented, as well as a computer experiment involving projections and estimations of box dimension.The second paper concerns sets for which different types of dimensions give different values. Given three arbitrary and different numbers in (0,n), a compact set in ℝn is constructed with these numbers as its Hausdorff dimension, lower box dimension and upper box dimension. Most important in this construction, is that the resulted set is homogeneous in the sense that these dimension properties also hold for every non-empty and relatively open subset.The third paper is about sets in space and their projections onto planes. Connections between the dimensions of the orthogonal projections and the dimension of the original set are discussed, as well as the connection between orthogonal projection and the type of projection corresponding to realistic x-ray. It is shown that the estimated box dimension of the orthogonal projected set and the realistic projected set can, for all practical purposes, be considered equal.
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| 7. |
- Nilsson, Daniel
(författare)
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Bioenergy from Swedish forests : A Study of extraction methods, quality and effects for forest owners
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The forest constitutes a very important element of renewable natural resources and makes a significant contribution to the Swedish bioeconomy. Biofuels are Sweden’s largest source of energy; of all the energy we use, 32% comes from biofuels, and of this approximately 85% comes from the forest and the forestry sector. In spite of this, logging residues constitute only a small component, compared to for example byproducts from sawmills and pulpindustry, and there is considered to be great potential for increasing their use.In 2019 the Swedish Forestry Agency issued new recommendations for logging residue harvest and ash recycling. This was a further development of the 2008 recommendations, which formed the foundation for how forest fuel producers work today, and were based on several decades of research into, for example, the impact on forest productivity and technological development of machinery. This practice of logging residue harvest aims to yield a dry and defoliated fuel where the needles are left at the clear felled area.However, if we are to increase the use of green renewable energy from forestry, it is very important to understand how different procurement systems affect the handling and storability of fuels from a quality perspective. It is also of great importance to understand, from the forest owners’ perspective, how removal of additional products from forestry influences nutritional balance and long-term productivity. If harvesting of logging residues does not affect long-term productivity, it is up to small-scale private forest owners to decide if removal of logging residues will be performed on their land. This thesis addresses some of these issues regarding removal of logging residues from the point of tree harvest up to the point of delivery to the energy conversion industry when the fuel chips are measured.Regarding different methods of handling of logging residues, the traditional method – dry-stacking – was compared with the, fresh-stacking method. The logging residues investigated came from stands that mainly consisted of Norway spruce (Picea abies (L.) Karst). The loads investigated in Paper 3 also came from logging of spruce-dominated forests. Both methods aim to dry the logging residues to an acceptable moisture content for delivery to the energyconversion industry. For the later part in the supply chain, moisture content measurements of logging residues were compared during a winter and summer season.The results of the studies indicate that the two methods do not create results that differ from what is allowed by the Swedish Forestry Agency and that they are quite similar with respect to dry mass- and nutrient removal from the clearfelled area. The results also show that similar yields and distributions of material are obtained from the logging residues with different stacking methods; in addition, the final felling itself, combined with the work performed by the forwarder operator, has a greater impact on the result than the method chosen for residue stacking of the logging residues. For the individual clear-felled area and the individual forest owner the increased removal associated with freshstacked logging residue has no major impact, however from a national perspective this small increase in removed logging residues may yield a supplement of between 0.5 – 1 TWh of green energy annually.Regardless of treatment, the studies indicated that the delivered fuel chips will have similar characteristics. The moisture content measurement techniques currently in use are sufficiently accurate and reliable. However, if the forest owner is unlucky and an error in measurement occurs or comminution and delivery happens during an especially wet period they may suffer a significant financial loss; indeed, it is generally not under the individual forest owners’ control when the logging residues are comminuted and delivered.
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| 8. |
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| 9. |
- Nilsson, Peter, 1982
(författare)
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Laser-welded corrugated core steel sandwich panels for bridge application
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The design of steel bridge decks has remained unchanged since the introduction of orthotropic decks. Orthotropic decks are expensive to produce, mainly due to high labor-costs. Furthermore, several joints (within the deck and between the deck and the surrounding structure) are highly fatigue sensitive, and the deck has a low stiffness in the transverse direction (i.e. perpendicular to the longitudinal stiffeners). This has in many cases led to premature deterioration and high maintenance costs. This thesis has a focus on laser-welded corrugated core steel sandwich bridge decks that have an increased stiffness-to-weight ratio and a more industrialized production with less complex detailing compared to conventional orthotropic steel decks. These enhancements lead to a more attractive solution with respect to economic and environmental sustainability.Structural analysis of a three-dimensional corrugated core sandwich panel using numerical methods is computationally heavy. In particular, the structural behavior of such panel in the transverse direction is rather complex. For that reason, this thesis is aimed at developing methods for simplified analysis incorporating homogenized beam and plate theories. Focus is put on predicting the stiffness and load effects in the direction transverse to the corrugation. A second aim of this thesis is to investigate the impact of variation of the production-dependent geometric parameters of the core-to-face joints of corrugated core steel sandwich panels on fatigue-relevant stresses in the vicinity of the laser stake welds.In order to utilize a simplified approach for static analysis of a corrugated core steel sandwich panel, a new analytical formulation for the transverse shear stiffness in the weak direction of the panel is presented in this thesis. To ensure that this stiffness property yields accurate predictions, the rotational rigidity of the weld region is simulated by a rotational spring. The magnitude of this spring is determined by a closed-form solution based on numerical and regression analyses. Both the transverse shear stiffness and the rotational spring is verified by numerical analyses and experiments. Furthermore, the impact of the variation of the production-dependent parameters is studied in this thesis by an extensive parametric study incorporating two-dimensional continuum numerical models. Numerical results are presented and discussed in detail. As an example, the parametric study shows that a misalignment between the weld-line and core direction can lead to a large increase of the fatigue-relevant stresses.
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| 10. |
- Nilsson, Peter, 1976
(författare)
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On Traffic Situation Predictions for Automated Driving of Long Vehicle Combinations
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The introduction of longer vehicle combinations for road transports than are currently allowed is an important viable option for achieving the environmental goals on transported goods in Sweden and Europe by the year 2030. This thesis addresses how driver assistance functionality for high-speed manoeuvring can be designed and realized for prospective long vehicle combinations. The main focus is the derivation and usage of traffic situation predictions in order to provide driver support functionalities with a high driver acceptance. The traffic situation predictions are of a tactical character and include a time horizon of up to 10 s.Data collection of manual and automated driving with an A-double combination was carried out in a moving-base driving simulator. The driving scenario was comprised of a relatively curvy and hilly single-lane Swedish county road (180). The driving trajectories were analysed and complemented with results from optimization. Based on observations of utilized accelerations it was proposed that the combined steering and braking should prioritize a smooth and comfortable driving experience.It was hypothesized that high driver acceptance of driver assistance functionality including automated steering and propulsion/braking, can be realized by utilizing driver models inspired by human cognition as an integrated part in the generation of traffic situation predictions. A longitudinal and lateral driver model based on optic information was proposed for lane-change manoeuvring.The driver model was implemented in a real-time framework for automated driving of an A-double combination on a multiple lane one-way road. Simulations showed that the framework gave reasonable results for maintain lane and lane change manoeuvres at constant and varying longitudinal velocities.
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