In this thesis we explore in particular the dynamics of a special type of quasi-particle in pi-conjugated materials termed polaron, the origin of which is intimately related to the strong interactions between the electronic and the vibrational degrees of freedom within these systems. In order to conduct such studies with the particular focus of each appended paper, we simultaneously solve the time-dependent Schrödinger equation and the lattice equation of motion with a three-dimensional extension of the famous Su-Schrieffer-Heeger (SSH) model Hamiltonian. In particular, we demonstrate in Paper I the applicability of the method to model transport dynamics in molecular crystals in a region were neither band theory nor perturbative treatments such as the Holstein model and extended Marcus theory apply. In Paper II we expand the model Hamiltonian to treat the revolution of phenylene rings around the sigma-bonds and demonstrate the great impact of stochastic ring torsion on the intra-chain mobility in conjugated polymers using poly[phenylene vinylene] (PPV) as a model system. Finally, in Paper III we go beyond the original purpose of the methodology and utilize its great flexibility to study radiationless relaxations of hot excitons. / Report code: LiU-TEK-LIC-2007:4.

Since its discovery, in the 1940's, radar (Radio Detection and Ranging) has become an important ranging sensor in many areas of technology and science. Most of the military and many civilian applications are unimaginable today without radar. With technology development, radar application areas have become larger and more available. One of these applications is Synthetic Aperture Radar (SAR), where an airborne radar is used to create high resolution images of the imaged scene. Although known since the 1950's, the SAR methods have been continuously developed and improved and new algorithms enabling real-time applications have emerged lately. Together with making the hardware components smaller and lighter, SAR has become an interesting sensor to be mounted on smaller unmanned aerial vehicles (UAV's). One important thing needed in the SAR algorithms is the estimate of the platform's motion, like position and velocity. Since this estimate is always corrupted with errors, particularly if lower grade navigation system, common in UAV applications, is used, the SAR images will be distorted. One of the most frequently appearing distortions caused by the unknown platform's motion is the image defocus. The process of correcting the image focus is called auto-focusing in SAR terminology. Traditionally, this problem was solved by methods that discard the platform's motion information, mostly due to the off-line processing approach, i.e. the images were created after the flight. Since the image (de)focus and the motion of the platform are related to each other, it is possible to utilise the information from the SAR images as a sensor and improve the estimate of the platform's motion. The auto-focusing problem can be cast as a sensor fusion problem. Sensor fusion is the process of fusing information from different sensors, in order to obtain best possible estimate of the states. Here, the information from sensors measuring platform's motion, mainly accelerometers, will be fused together with the information from the SAR images to estimate the motion of the flying platform. Two different methods based on this approach are tested on the simulated SAR data and the results are evaluated. One method is based on an optimisation based formulation of the sensor fusion problem, leading to batch processing, while the other method is based on the sequential processing of the radar data, leading to a filtering approach. The obtained results are promising for both methods and the obtained performance is comparable with the performance of a high precision navigation aid, such as Global Positioning System (GPS). / LINK-SIC

The enormous competition in the telecommunications market results in the necessity of optimized and cost-efficient networks for the operators and service providers. Tracing users cost-efficiently is one of the major challenges in the study of location management of wireless cellular  networks. Tracking Area (TA) is a logical grouping of cells in Long Term Evolution (LTE) networks. TA manages and represents the location of User Equipments (UEs). One of the well-known performance consideration is the signaling overhead of tracking area update versus that for paging. This thesis deals with planning and optimization of tracking area configuration in LTE networks. TA design must be revised over time in order to adapt to changes and trends in UE location and mobility patterns. Re-optimization of the initial planning subject to different cost budgets is one of the problems considered in the thesis. By re-optimization, the design is successively improved by re-assigning some cells to TAs other than their original ones. To solve the resulting problem, an algorithm based on repeated local search is developed. By extending the line of research, the trade-off between the performance in terms of overall signaling overhead of the network and the reconfiguration cost is considered. This trade-off is modeled as a biobjective optimization problem to which the solutions are characterized by pareto-optimality. Solving the problem delivers a host of potential trade-offs among which the selection can be based on the preferences of a decision-maker. An integer programming model and a heuristic based on genetic algorithm are developed for solving the problem in large-scale networks. In comparison to earlier generations of cellular networks, LTE systems allow for a more flexible configuration of TA design by means of Tracking Area List (TAL). How to utilize this flexibility in applying TAL to large-scale networks remains unexplored. In this thesis, three approaches for allocating and assigning TA lists have been presented, and their performance is compared with each other, as well as with the standard location management scheme. Automatic reconfiguration is an important element in LTE. The network continuously collects UE statistics, and the management system adapts the network configuration to changes in UE distribution and demand. In this thesis an evaluation of dynamic configuration of TA design, including the use of TAL, has been performed and compared to the static configuration by using a case study.

Wide band gap semiconductors, Zinc Oxide (ZnO), Gallium Nitride (GaN) and Silicon Carbide (SiC) have been emerged to be the most promising semiconductors for future applications in electronic, optoelectronic and power devices. They offer incredible advantages in terms of their optical properties, DC and microwave frequencies power handling capability, piezoelectric properties in building electromechanical coupled sensors and transducers, biosensors and bright light emission. For producing high quality devices, thermal treatment always plays an important role in improving material structural quality which results in improved electrical and optical properties. Similarly good quality of metal–semiconductor interface, sensitive to the semiconductor surface, is always required. In this thesis we report the study of the interface states density for Pd/Ti/Au Schottky contacts on the free-standing GaN and post fabrication annealing effects on the electrical and optical properties of ZnO/Si hetero-junction diodes. The determination of interface states density (NSS) distribution within the band gap would help in understanding the processes dominating the electrical behavior of the metal–semiconductor contacts. The study of annealing effects on photoluminescence, rectification and ideality factor of ZnO/Si hetero-junction diodes are helpful for optimization and realization to build up the confidence to commercialize devices for lightening. A comparison of device performance between the physical simulations and measured device characteristics has also been carried out for pd/ZnO Schottky diode to understand the behavior of the devices. This research work not only teaches the effective way of device fabrication, but also obtains some beneficial results in aspects of their optical and electrical properties, which builds theoretical and experimental foundation for much better and broader applications of wide band gap semiconductor devices.

The purpose of this thesis is to describe and analyse purchasing strategies and their interdependence with the production process and supplier relationships in industrialized housing. The thesis is a multiple case study of four Swedish industrialized timber-housing manufacturers. The case studies included interviews with top managers concerning purchasing, production and supplier relationships. Production is considered the heart of the company. Therefore, to gain an in-depth knowledge of how production affects purchasing and thus supplier relationships and vice versa, observations were made to study the production process. Many different parts and competences need to be coordinated in the creation of a house. In the West, the construction industry has been heavily criticized for low efficiency and effectiveness. Conclusions from the case studies showed that codevelopment, customization and secure deliveries are regarded highly by industrial house builders and to obtain them, long-term relationships with suppliers are preferred. Industrialized house builders are argued to have more long-term relationships with their suppliers than traditional on-site builders. Industrial house builders choose their suppliers based on the purchased products’ value-in-production rather than price. Product and process innovations created in collaboration with suppliers seem to be a way to enhance the production process of houses. Through the site resource of the factory, industrial house builders have the potential to refine their processes in win-win partnerships with suppliers for a more efficient and effective production of houses, as onsite work is harder to standardize and control.

In aircraft development, it is crucial to understand and evaluate behavior, performance, safety and other aspects of the systems before and after they are physically available for testing. Simulation models are used to gain knowledge in order to make decisions at all development stages. Modeling and simulation (M&S) in aircraft system development, for example of fuel, hydraulic and electrical power systems, is today an important part of the design process. Through M&S a problem in a function or system is found early on in the process. An increasing part of the end system verification relies on results from simulation models rather than expensive testing in flight tests. Consequently, the need for integrated models of complex systems, and their validation, is increasing. Not only one model is needed, but several interacting models with known accuracies and validity ranges are required. The development of computer performance and modeling and simulation tools has enabled large-scale simulation. This thesis includes four papers related to these topics. The first paper describes a modeling technique, hosted simulation, how to simulate a complete system with models from different tools, e.g. control software from one tool and the equipment model from another. The second paper describes the use of M&S in the development of an aircraft. The third and fourth papers describe how to increase knowledge of the model’s validity by sensitivity analysis and the uncertainty sources. In papers one and three an unmanned aerial vehicle is used as an example and in paper four a pressure regulator is the application.

An introduction of computer software into mathematics classrooms makes the didactical situation more complex compared with previous learning environments (Blomhøj, 2005). A technological tool becoming a mathematic work tool in the hands of the students is a process that has turned up unexpectedly complex (Artigue, 2002). In addition to this problem, the teachers as the users of the tool go through the same process, while, at the same time, trying to integrate the tool into their teaching activities in a meaningful way. For these reasons it seems important to contribute to the research focused on the learning and teaching conditions in environments, where computer software is newly introduced, in order to better understand impacts of the introduction of different software in mathematics classrooms. In this study the dynamic mathematical software GeoGebra was used. GeoGebra is freely available for a number of platforms and has drawn much attention during the last years with growing user communities (www.GeoGebra.org). However, being generally available just recently, there are, comparatively, few studies on the use of GeoGebra in classroom settings. In this thesis the introduction and integration of GeoGebra was investigated in two studies with different perspectives. In the first study students’ work with GeoGebra in their mathematical activities related to the integral concept has been researched. In the second study teachers’ utilization of the didactical potential has been investigated. The results of the two studies show that GeoGebra as a mathematical tool in the hands of the students and the teachers can have a significant role in supporting their mathematical work if exploited in a, from a didactical perspective, adequate way. A learning and teaching environment based on GeoGebra bring with it a possibility to work with mathematical concepts in a broader way compared with blackboard based classrooms. GeoGebra’s facilities makes it possible to communicate mathematics in different ways and expressing mathematical concepts in different representations in a more direct way than in non dynamical environments. Communicating mathematics in different ways and expressing mathematics knowledge through different representations is of significant importance for students, not least in relation to the new curriculum for mathematics in Sweden (The Swedish National Agency for Education, 2011), where these aspects are explicitly named as aims for students to work towards. On the other hand, the investigations also showed that the introduction and the integration of GeoGebrawas a complex process for both the students and the teachers in this research. The introduction and integration of the software in the students’ mathematical activities made the didactical situation more complex and a differentiation of students’ work with the software was observed. For some students the use of the software seemingly supported their mathematical work, and at the same time for some students the result was the opposite; the use of the software was seen as a disturbing factor in their mathematical activities. When it comes to the study of teachers’ work with GeoGebra the investigations revealed that they encountered different types of obstacles that prevented them from utilizing the full didactical potential of the software in their teaching of mathematics. Three different types of obstacles were identified: technical - a teacher is not able to operate the software in the intended way; epistemological - a teacher is not aware of the didactical potential of GeoGebra and howto exploit it in in a way that supports students’ learning of integrals; didactical - a teacher is not aware of the complexity of technology based environments or he/she is aware of this aspect, but not comfortable with his/her competence in carrying out the process of integration of the software into his/her teaching without external help and support. Even if it is difficult to see the software detached from the context in this research, it seems that many of the obstacles perceived by the teachers in the experimental group, as well as difficulties students perceived in their work with the software, were related to the fact that they were inexperienced with the software and, consequently, lacked in knowledge in how to exploit its features in their mathematical activities. As it seems, the teachers would encounter the same obstacles every time they try to integrate a new, to them unfamiliar, software into their teaching practice. Also many of the students would experience same difficulties if they are not adequately supported in this process. Based on this, there are reasons to believe that problems with integration of GeoGebra into mathematics classrooms identified in this research would be similar in relation to integration of other dynamic mathematic software into mathematics classrooms, or even broader, other types of software as e.g. Computer Algebra Systems (CAS), as long as the integration considers the use of an unfamiliar software.

Klassrumsbedömning i matematik på gymnasienivå är en licentiatstudie med en intention att närma sig, fånga upp samt förstå och tolka lärares ageranden, tankar, upplevelser och reflektioner inom och om bedömningen i matematik i gymnasiet. En annan avsikt är delvis att fylla i luckan mellan det målrelaterade kursbedömningssystemet och det praktiska fältet med en kvalitativ forskningsstudie om lärarerfarenheter från gymnasiets matematikkurser.Studien kan inte på något sätt betraktas som uttömmande. Den är selektiv till sin natur. Det finns många andra faktorer som också påverkar de deltagande lärarnas handlingar, funderingar och beslut inom bedömningsfältet av vilka endast ett fåtal berörs av studien. Det finns även så många matematiklärare utanför studien. Lägg likaså till mer eller mindre involverade och intresserade organisationer och institutioner.Intervjuer och fokusgruppsamtal med ett antal matematiklärare från diverse gymnasieskolor har spelats in och detaljerat analyserats genom transkriberingar. Den metodanalytiska och den teoretiska ansatsen från grundad teori har succesivt lett till urskiljandet av åtta typer av bedömningsstrategier: den intuitiva, den inväntande, den kontinuerliga, den likvärdiga, den målinriktade, den provinriktade, den undervisningskopplade samt självbedömningsstrategin och till en teori om hur lärare beskriver och reflekterar om bedömning i matematik på gymnasiet. Strategierna uppvisar en rikedom i lärarnas resonemang om bedömning. Teorin har avslutningsvis fört studien till ett antal begrepp och tillhörande kategoriseringar som har underättat förstaelsen av lärarnas handlingar och resonemang inom matematikbedömningen på gymnasiet. / Classroom Assessment in Mathematics at secondary school level is a licentiate study with the intention to approach and interpret teachers’ actions, thoughts and experiences of assessment in mathematics. Another intention of the study is to, through qualitative research on teachers’ experiences of the mathematical courses, bridge the gap between the target-related course system and teachers ́ practical work. Finally, the intent is to provide qualitative formative feedback of the course assessment regarding teachers ́ evaluation strategies. A more qualitative feedback from evaluation, analysis, discussion and reflection will undoubtedly lead to improved mathematics assessment.There are many other factors that also affect teachers’ activities, thoughts and decisions within the assessment area of which few are only concerned within the study. In the present study, interviews and focus-group discussions have been conducted with a group of secondary mathematics teachers. All interviews were tape recorded and detailed analysed in order to give an insight into teachers ́ thoughts and action and further, their experiences of assessing students ́ mathematic knowledge. The analytic and theoretical method of the grounded theory has gradually led to eight assessment strategies and a theory of how the teachers describe and reflect on assessment in mathematics at upper secondary school. Those strategies were: the intuitive, the awaited, the continuous, the equivalent, the target-related, the test-oriented, the instruction-connected and self-assessment strategy. Finally the theory that was grounded out of the data brought a number of concepts and their categorizations. In turn the concepts and the categorizations have facilitated the understanding of the teachers’ activities and thinking in mathematics assessment at upper secondary school.The study gives an important insight into teachers ́ assessment strategies and the reason for their actions, something which has implication for mathematics education in upper secondary school as well as teacher education practices.

Thermal barrier coating systems (TBCs) are used in gas turbines to prevent high-temperature degradation of metallic materials in the combustor and turbine. One of the main concerns regarding TBCs is poor reliability, and accurate life prediction models are necessary in order to fully utilise the beneficial effects of TBCs. This research project aims at developing deeper understanding of the degradation and failure mechanisms acting on TBCs during high temperature exposure, and to use this knowledge to improve life assessments of TBCs. The present work includes a study on the influence of coating interface morphology on the fatigue life of TBCs and a study on the influence of some different heat treatments on the adhesive properties of TBCs. The influence of coating interface morphology on fatigue life has been studied both experimentally and by modelling. Large interface roughness has been found experimentally to increase fatigue life of TBCs. The modelling work do, to some extent, capture this behaviour. It is evident, from the study, that interface morphology has a large impact on fatigue life of TBCs. Three thermal testing methods, that degrade TBCs, have been investigated: isothermal oxidation, furnace cycling and burner rig test. The degraded TBCs have been evaluated by adhesion tests and microscopy. The adhesion of TBCs has been found to depend on heat treatment type and length. Cyclic heat treatments, (furnace cycling and burner rig test), lower the adhesion of TBCs while isothermal oxidation increases adhesion. The fracture surfaces from the adhesion tests reveal that failure strongly depends on the pre-existing defects in the TBC.

In this thesis, we investigate two problems in robustness analysis of uncertain systems with structured uncertainty. The first problem concerns the robust finite frequency range H2 analysis of such systems. Classical robust H2 analysis methods are based on upper bounds for the robust H2 norm of a system which are computed over the whole frequency range. These bounds can be overly conservative, and therefore, classical robust H2 analysis methods can produce misleading results for finite frequency range analysis. In the first paper in the thesis, we address this issue by providing two methods for computing upper bounds for the robust finite-frequency H2 norm of the system. These methods utilize finitefrequency Gramians and frequency partitioning to calculate upper bounds for the robust finite-frequency H2 norm of uncertain systems with structured uncertainty. We show the effectiveness of these algorithms using both theoretical and practical experiments.