<p>The knowledge regarding early stages in polymer crystallisation remains inconclusive due to experimental limitations. The reason is that the initially formed polymer crystals rearrange rapidly at the crystallisation temperature. Faster experimental techniques or simulation would be suitable alternatives to approach the problem. Another possibility would be to use constrained polymer structures, in which crystal rearrangement would be slower. Star polymers with crystallisable arms may be structures sufficiently constrained to be captured in their early crystallisation stages.</p><p>This study reports the crystallisation behaviour of linear poly(c-caprolactone) (PCL) and star polymers based on dendritic cores with grafted PCL arms. Wide angle X-ray scattering proved that the crystal structures of the different polymers were the same. The samples were also studied by differential scanning calorimetry, finding that the star PCL’s had lower crystallinity, lower rate of crystal rearrangement and higher equilibrium melting point than the linear analogues. Polarized optical microscopy showed that the star polymers crystallized slower and had greater tendency to form spherulites and higher fold surface free energy than linear PCL. The single crystal morphology was more irregular in the star polymers as observed by transmission electron microscopy.</p><p>These findings confirm the constraining effect of the dendritic cores in the crystallisation of the PCL arms, which retard molecular rearrangement during crystallisation and turn the studied star polymers into excellent candidates to investigate the early stages in polymer crystallisation.</p>

In the past two decades, robotics and autonomous vehicles have received ever increasing research attention. For an autonomous robot to function fully autonomously alongside humans, it must be able to solve the same tasks as humans do, and it must be able to sense the surrounding environment. Two such tasks are addressed in this thesis, using data from laser range sensors. The first task is recognising that the robot has returned to a previously visited location, a problem called loop closure detection. Loop closure detection is a fundamental part of the simultaneous localisation and mapping problem, which consists of mapping an unknown area and simultaneously localise in the same map. In this thesis, a classification approach is taken to the loop closure detection problem. The laser range data is described in terms of geometrical and statistical properties, called features. Pairs of laser range data from two different locations are compared by using adaptive boosting to construct a classifier that takes as input the computed features. Experiments using real world laser data are used to evaluate the properties of the classifier, and the classifier is shown to compare well to existing solutions. The second task is keeping track of objects that surround the robot, a problem called target tracking. Target tracking is an estimation problem in which data association between the estimates and measurements is of high importance. The data association is complicated by things such as noise and false measurements. In this thesis, extended targets, i.e. targets that potentially generate more than one measurement per time step, are considered. The multiple measurements per time step further complicate the data association. Tracking of extended targets is performed using an implementation of a probability hypothesis density filter, which is evaluated in simulations using the optimal sub-pattern assignment metric. The filter is also used to track humans with real world laser range data, and the experiments show that the filter can handle the so called occlusion problem.

This thesis presents the design and the optimization of a wireless remote monitoring and control system utilizing the ZigBee protocol. From the system architecture point of view, the remote wireless monitoring and control system is mainly combined by 3 parts, the wireless sensor network, the message gateway and the web service. In order to increase the system flexibility and the reconfigurability, each part communicates with each other by using the standard communication protocols. The wireless sensor network of the system can be deployed in many different locations. The network includes the sensor module, the message relay, the control module and the network coordinator. The sensor module calculates the sensor information (e.g., temperature) periodically and sends the message to the network coordinator. If the radio link of the sensor module is not long enough to reach the coordinator, a message relay could be utilized in between to forward the message to the destination. Meanwhile, the message relay can be utilized as a control module as well. For example, when connected with the air conditioning system (radiator or ventilation), the control device can generate control signal to adjust the temperature and the relative humidity. The network coordinator is the root of the network. When the network coordinator receives the sensor information from the sensor module, it forwards the message to the connected gateway. On the other hand, the coordinator also receives the control command from the gateway. When the control command is received, the network coordinator forwards the control command to the corresponding control device of the wireless sensor network to execute the command. Generally speaking, it is the wireless sensor network part provides the sensor information and executes the control commands in the system. The gateway works as a translator and synchronizer between the wireless sensor network and the web service. It communicates with the wireless sensor network via the connection of the network coordinator. When receiving the sensor information from the wireless sensor network, the gateway forwards the message to the web service through the Internet. On the other hand, the gateway also receives control commands from the web service. When the gateway receives the control command from the web service, it forwards the command to the network coordinator of the wireless sensor network. Moreover, the gateway also works as a local monitoring and control agent. The gateway can be utilized to monitor and control the local sensor network without login to the web service. During the network deployment, the gateway needs to be equipped for each wireless sensor network. Different gateways can communicate with the web service via the Internet at the same time. The web service contains the sensor information uploaded from different locations. When the control command is received from the user configuration, the web service forwards the control command to the correct local server. From the user point of view, the web service is a website which can be accessed by a normal web browser. Users can register the website to apply for monitoring and control privilege. The monitoring function provides the graphical presentation of the sensor information from different locations. The control function of the system includes the ON/OFF control, temperature control and humidity control. In order to increase the system reliability, extra optimizations are developed in different parts of the system. In the wireless sensor network, the power consumption of the battery powered sensor module is optimized. A method is discovered to manage the network topology and the message forwarding pattern. Moreover, an alternative routing algorithm is designed which could be utilized by the coordinator to communicated with the sensor network. This method is verified to be much more efficient than the original algorithm utilized by the sensor network. Finally, a general purpose communication reliability enhancement framework is developed for the wireless sensor network. It helps the wireless sensor network to handle the exceptions without interference to the sensor network applications. In the gateway part, the Internet connection status is checked all the time. When the Internet connection is broken, sensor messages sent from the coordinators are buffered in the gateway to avoid the message lost. Finally, the remote monitoring and control system has received a nomination for the Swedish Embedded Award 2010 and been demonstrated at the Scandinavia Embedded Conference 2010 in Stockholm.

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.

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&amp;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&amp;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&amp;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.

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.

From its first appearance, wireless communications has changed thelife for many people worldwide. Currently, more than half of the world's population are using wireless devices for various purposes on a daily basis. While the early wireless systems could provide simple and specific low-rate services, today's systems can support a variety of more advanced services some of which require high data rate communications. This includes for example web-browsing and streaming multimedia applications. To meet the high demands on the current systems, many technical solutions have been proposed. Many of these solutions are powerful in the sense of boosting the system performance, but on the other hand, they impose a substantial control signaling overhead on the system. The control signaling refers to sending the control information that is necessary to establish and/or maintain the connection as opposed to the payload data that is transmitted during the connection. In this thesis, we are interested in evaluating the relations between the gain of deploying new techniques and the amount of control signaling overhead they incur. Moreover we are interested in finding efficient algorithms that can potentially reduce the control signaling overhead. More specifically, we first focus on the part of the control signaling overhead that concerns sending the scheduling assignments that describe how the channel resources are allocated among the users. We compare two ways for the signaling of scheduling assignments and we will study how different parameters such as scheduling granularity impact the control signaling overhead. We also provide two schemes that reduce the control signaling overhead substantially. We then provide an algorithm for fast blind identification of channel codes. This algorithm is very useful in improving the so-called blind decoding performance. This is essential since blind decoding is used to achieve adaptive modulation and coding in the control channel of some of the wireless communication systems such as 3GPP Long Term Evolution.

The ability to measure and quantify myocardial motion and deformation provides a useful tool to assist in the diagnosis, prognosis and management of heart disease. Myocardial motion can be measured by means of several different types of data acquisition. The earliest myocardial motion tracking technique was invasive, based on implanting radiopaque markers into the myocardium around the left ventricle, and recording the marker positions during the cardiac cycle by biplane cineradiography. Until recently, this was the only method with high enough spatial resolution of three-dimensional (3D) myocardial displacements to resolve transmural behaviors. However, the recent development of magnetic resonance imaging techniques, such as displacement encoding with stimulated echoes (DENSE), make detailed non-invasive 3D transmural kinematic analyses of human myocardium possible in the clinic and for research purposes. Diastolic left ventricular filling is a highly dynamic process with early and late transmitral inflows and it is determined by a complex sequence of many interrelated events and parameters. Extensive research has been performed to describe myocardial kinematics during the systolic phase of the cardiac cycle, but not by far the same amount of research has been accomplished during diastole. Measures of global and regional left ventricular kinematics during diastole are important when attempting to understand left ventricular filling characteristics in health and disease. This thesis presents methods for invasive and non-invasive quantification of cardiac kinematics, with focus on diastole. The project started by quantification of changes in global left ventricular kinematics during diastolic filling. The helical myocardial fiber architecture of the left ventricle produces both long- and short-axis motion as well as torsional deformation. The longitudinal excursion of the mitral annular plane is an important component of left ventricular filling and ejection. This was studied by analyzing the contribution of mitral annular dynamics to left ventricular filling volume in the ovine heart. In order to quantify strains for a specific body undergoing deformation, displacements for a set of internal points at a deformed configuration relative to a reference configuration are needed. A new method for strain quantification from measured myocardial displacements is presented in this thesis. The method is accurate and robust and delivers analytical expressions of the strain components. The developed strain quantification method is simple in nature which aids to bridge a possible gap in understanding between different disciplines and is well suited for sparse arrays of displacement data. Analyses of myocardial kinematics at the level of myocardial fibers require knowledge of cardiac tissue architecture. Temporal changes in myofiber directions during the cardiac cycle have been analyzed in the ovine heart by combining histological measurements of transmural myocardial architecture and local transmural strains. Rapid early diastolic filling is an essential component of the left ventricular function. Such filling requires a highly compliant chamber immediately after systole, allowing inflow at low driving pressures. Failure of this process can lead to exercise intolerance and ultimately to heart failure. A thorough analysis of the relation between global left ventricular kinematics and local myocardial strain at the level of myocardial fibers during early diastole in the ovine heart was performed by applying the method for strain quantification and the technique for computing temporal changes in myocardial architecture on measures of myocardial displacements and tissue architecture in the ovine heart. As data acquisition technologies develop, quantification methods for cardiac kinematics need to be adapted and validated on the new types of data. Recent improvements of DENSE magnetic resonance imaging enable non-invasive transmural strain analyses in the human heart. The strain quantification method was first tailored to displacement data from a surgically implanted bead array but has been extended to applications on non-invasive DENSE data measured in two and three dimensions. Validation against an analytical standard reveals accurate results and in vivo strains agree with values for normal human hearts from other studies. The method has in this thesis been used with displacement data from invasive marker technology and non-invasive DENSE magnetic resonance imaging, but can equally well be applied on any type of displacement data provided that the spatial resolution is high enough to resolve local strain variations.

This thesis focuses on improving and extending the available toolset for Eulerian, i.e. grid based, free surface fluid animation and level set based surface tracking in the context of computer graphics and visual effects. More specifically three novel methods are presented each aimed towards reducing the amount of computer memory required for producing high resolution animations of incompressible free surface fluids. Each method is primarily developed for, but not limited to, the popular Stable Fluids method. Eulerian free surface fluid animation has historically required a large amount of computer memory, especially when high resolution results are desired. This problem has recently been addressed through the development of dynamic computational grids like the Dynamic Tubular Grid (DT-Grid) for level set computations. However, when animating free surface fluids a large amount of tracker particles are often added to the level set geometry in order to provide more accurate tracking of fluid surfaces. As a result the particle level set (PLS) method typically requires two orders of magnitude more memory than a DT-Grid level set. In order to reduce the gap in memory requirement between the level set and the particles this thesis introduces a fast and efficient compression method for such tracker particles. This compression is optionally combined with a specialized external memory algorithm that allows particle and level set data to be efficiently streamed back and forth between primary memory and secondary storage devices such as hard disk drives. The particle compression scheme is able to reduce the size of a DT-Grid particle level set by more than 65% while only inducing a 5% penalty to performance. If combined with the external memory algorithm particle level sets of virtually any size and resolution can be used in free surface fluid animations. The induced performance penalty of the combined scheme depends on the performance of the external storage device, however when using a traditional hard disk drive a 70% increase in simulation time was measured. This thesis also presents a purely Eulerian alternative to the PLS method through the introduction of a dual resolution level set representation. The method replaces the tracker particles with a level set of higher resolution, thus significantly increasing surface tracking accuracy compared to the unaided level set. The scheme is able to produce high quality results using up to 94% less memory than a PLS. The core component of the method is the Spatially Adaptive Morphology (SAM) filter which connects the high resolution representation of the level set with the lower resolution fluid, thus providing plausable animation also for small and/or thin surface features. A sheet preserving extension to the SAM filter is also presented that is able to preserve thin sheets of fluid indefinitely if so desired. Although this method adds mass to the simulation it is highly useful for animating phenomena like splashes, fountains and waterfalls. The final method presented in this thesis concerns the efficient local animation of oceans and other very large free surface fluids.For such scenarios large amounts of memory and computation time can be saved by only computing accurate fluid physics in a local fluid region immediately surrounding a point of interest. The fluid outside this region can then be animated using less accurate but significantly faster and less memory demanding models. However, for this approach to be accurate the local fluid must be contained in such a way that it behaves as if still part of a larger fluid. This thesis enables the local simulation of a larger body of fluid by introducing three different non-reflective boundary conditions for free surface fluid animation using a modified Stable Fluids method. Two simple wave dampening boundaries are presented as well as a significantly more advanced wave absorbing boundary based on the Perfectly Matched Layer (PML) approach. All three boundaries are shown to be effective in preventing wave reflection given large enough boundary regions. However the PML boundary is significantly more efficient, typically absorbing waves at a fraction of the distance required by the other two methods.