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  • 1.
    Abrahamsson, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Using Function as a Service for Dynamic Application Scaling in the Cloud2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Function as a Service is a new addition to cloud services that allow a user to execute code in form of a function, in the cloud. All underlying complexity is handled by the cloud provider and the user only pay per use. Cloud services have been growing significantly over the past years and many companies want to take advantages of the benefits of the cloud. The cloud services deliver computing resources as a service over a network connection, often by the Internet. To use the benefit of the cloud, one can not just move an application to the cloud and think that it will solve itself. First of all, an application needs to be optimized to be able to take advantages of the cloud. Therefore, together with Tieto, a microservice architecture have been the main architectural pattern when Function as a Service has been evaluated. A major problem with applications, both application built with a monolithic and microservice architecture, is to handle great amounts of information flows. An application may have scaling issues when an information flow becomes too large.

    A person using Function as a Service does not have to buy, rent or maintain their own servers. However, Function as a Service has a certain memory and runtime restrictions, so an entire application cannot be applied to a Function as a Service. This thesis examines the possibility of using Function as a Service in different architectural environments and estimating the cost of it. Function as a Service is a new addition to cloud services, so cloud providers are also compared and evaluated in terms of the Function as a Service functionality. Function as a Service has been tested directly on various

    cloud platforms and even developed and executed locally, encapsulated in containers. The results show that Function as a Service is a good complement to an application architecture. The results also show that Function as a Service is highly flexible and cost-effective, and it is advantageous compared to physical servers and Virtual Machines. Depending on how a function is built, the developer can lower the cost even more by choosing the cloud supplier that fits best for their use. With the flexibility of Function as a Service, applications can handle greater information flow without bottlenecks in the infrastructure and therefore, becomes more efficient and cost-effective. 

  • 2.
    af Ekenstam, Love
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Modellering av signalbehandlingen i ett cochleaimplantat och utvärdering av modellen.2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A program that simulates the signal processing in a cochlear implant using the signal processing strategy ACE (Advanced Combination Encoder) was constructed. Its main purpose is to, in advance, predict and test different implant settings with the purpose to be able to predict individual patient's differences in implant settings.

     

    The program was validated using output signals processed by Cochlear Limited using their own Matlab Toolbox for implant research, NMT (Nucleus Matlab Toolbox). Identical signals were processed by the program and then compared with NMT:s output. The outputs, produced with several different identical settings matched each other well.

     

    The amplitude compression function, a vital part of the signal processing, also matched well, apart from a relative loss of strength at high input amplitudes. The program will now be used by the cochlear implant section at Uppsala University Hospital to try out individual settings for cochlear implant users. The hope for the future is that better implant settings will lead to improved speech and sound experience, especially, in the long run, with regards to music.

  • 3.
    Agerberg, Gösta
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Solving the Vehicle Routing Problem: using Search-based Methods and PDDL2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this project the optimization of transport planning has been studied. The approach was that smaller transport companies do not have the capability to fully optimize their transports. Their transport optimization is performed at a company level, meaning that the end result might be optimal for their company, but that potential for further optimization exists.

    The idea was to build a collaboration of transport companies, and then to optimize the transports globally within the collaboration. The intent was for the collaboration to perform the same driving assignments but at a lower cost, by using fewer vehicles and drivers, or travel shorter distance, or both combined. This should be achieved by planning the assignments in a smarter way, for example using a company's empty return journey to perform an assignment for another company.

    Due to the complexity of these types of problems, called Vehicle Routing Problem (VRP), shown to be NP-complete, search methods are often used. In this project the method of choice was a PDDL-based planner called LPG-td. It uses enforced hill-climbing together with a best-first search to find feasible solutions. The method was tested for scaling, performance versus another method and against time, as well as together with a real-life based problem.

    The results showed that LPG-td might not be a suitable candidate to solve the problem considered in this project. The solutions found for the collaboration were worse than for the sum of individual solutions, and used more computational time. Since the solution for the collaboration at most should be equal to the sum of individual solutions, in theory, this meant that the planner failed.

  • 4.
    Agnarsson, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Simulation of a radar in Flames: a ray based radar model2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report a radar model is modeled and implemented in a simulation framework

    called Flames. The focus is to investigate how and if electromagnetic waves emitted

    from the radar antenna can be simulated by different methods and how these

    methods can be implemented to work in real-time simulations. The radar model

    developed in this report is based on ray tracing and ray propagation techniques

    developed by the author. The model considers varying refractive indices that

    describes both standard atmospheres and atmospheres where ducting occur.

    Preparatory studies are also made to model ground reflection by ray tracing

    techniques. Other simulation techniques, such as the Finite-Difference Time-Domain

    method and the Split-Step Parabolic Equation method, are furthermore considered

    for radar simulation applications. The results show that ray tracing in conjunction

    with geometrical optics is a valid method for simulating electromagnetic waves in

    simple atmosphere models.

  • 5.
    Ahlgren Peters, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    A SIMULATION WITH FINITE ELEMENTS TO MODEL STEEL SHEET SLITTING: A Master Thesis in Engineering Physics2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A steel slitting process is simulated using FEM (Finite Element Method) in order to see potential defects along the edge in a steel sheet after it has been cut. The model's results were compared to microscope images of the steel sheet in order to verify accuracy. The purpose is conceptual and to find a model that successfully simulates a steel cutting process and (hopefully) how the edge depends on different parameters. The model developed seems to achieve this task, and a more thorough calibration of the model could result in (more) optimal parameters for the machine to use.

  • 6.
    Ahlkrona, Josefin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Implementing Higher Order Dynamics into the Ice Sheet Model SICOPOLIS2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ice sheet modeling is an important tool both for reconstructing past ice sheets and predicting their future evolution, but is complex and computationally costly. It involves modeling a system including the ice sheet, ice shelves and ice streams, which all have different dynamical behavior. The governing equations are non-linear, and to capture a full glacial cycle more than 100,000 years need to be simulated. To reduce the problem size, approximations of the equations are introduced. The most common approximation, the Shallow Ice Approximation (SIA), works well in the ice bulk but fails in e.g. the modeling of ice streams and the ice sheet/ice shelf coupling. In recent years more accurate models, so-called higher order models, have been constructed to address these problems. However, these models are generally constructed in an ad hoc fashion, lacking rigor. In this thesis, so-called Second Order Shallow Ice Approximation (SOSIA) equations for pressure, vertical shear stress and velocity are implemented into the ice sheet model SICOPOLIS. The SOSIA is a rigorous model derived by Baral in 1999 [3]. The numerical solution for a simple model problem is compared to an analytical solution, and benchmark experiments, comparing the model to other higher order models, are carried out. The numerical and analytical solution agree well, but the results regarding vertical shear stress and velocity differ from other models. It is concluded that there are problems with the model implemented, most likely in the treatment of the relation between stress and strain rate.

     

  • 7.
    Ahlström, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Characterizing the state of water in an amorphous magnesium carbonate using Dielectric spectroscopy2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the industry of today, materials which can adsorb and hold large amounts of water are playing an important role. Here, the free and bound water carrying capacity of an amorphous magnesium carbonate is investigated. It is also determined how these parameters depend on the relative humidity of the surrounding environment. To do this, the technique of dielectric spectroscopy is employed. Along with the water binding properties, the concentration of charge carriers and the diffusion coefficient was determined. A smaller part of around 10-30 % of the water adsorbed was shown to behave as free water in the material. The concentration of charge carriers was calculated to be in an order of magnitude of 1018-1022 m-3 for the higher relative humidity environments. The diffusion coefficient was shown to be about 5*10-9 m2/s for the adsorption spectrum. This value is in good agreement with the value for OH- ions in water.

  • 8.
    Ahnesjö, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tomographic reconstruction of subchannel void measurements of nuclear fuel geometries2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Westinghouse FRIGG loop in Västerås, Sweden, has been used to study the distribution of steam in the coolant flow of nuclear fuel elements, which is known as the void distribution. For this purpose, electrically heated mock-ups of a quarter BWR fuel bundles in the SVEA-96 geometry were studied by means of gamma tomography in the late 1990s. Several test campaigns were conducted, with good results, but not all the collected data was evaluated at the time. In this work, tomographic raw data of SVEA-96 geometry is evaluated using two different tomographic reconstruction methods, an algebraic (iterative) method and filtered back-projection. Reference objects of known composition (liquid water) are used to quantify the decrease in attenuation arising from the presence of the void, which is used to create a map of the void in the horizontal cross sections of the fuel at various axial locations. The resulting detailed void distributions are averaged over subchannels and the subchannel steam core for comparison with simulations. The focus of this work is on the void distribution at high axial locations in the fuel, in fuel bundles with part-length fuel-rods. Measurements in the region above the part-length rods are compared with simulations and the reliability of each method is discussed. The algebraic method is found to be more reliable than the filtered back-projection method for this setup. A reasonable agreement between measurements and predictions is shown. The void, in both cases, appears to be slightly lower in the corner downstream the part-length rods.

  • 9.
    Aiesh, Basel
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Centre for Image Analysis.
    Measurement of dispersion barriers through SEM images2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis digital image analysis is applied to Scanning Electron Microscope imagesof dispersion barriers to measure specific properties. The thin barriers are used asprotection for paperboard packaging and are made of polymers and fillers. The orientation, area, length and density distributions of the fillers determine the functionality and quality of the barrier. Methods built on image analysis tools are developed with the objective to measure these quantities. Input for the methods are Scanning Electron Microscope images showing the cross-section of the barriers. To make the images relevant for the methods they are preprocessed by reducing noise and distinguishing fillers from the background.

    For measuring the orientation distribution of the fillers two different methods are implemented and compared. The first one is based on a structure tensor and the other one applies a covariance matrix. The structure tensor is preferable because of its flexibility and better performance for complex images. The area and length distributions are measured by applying mathematical morphology together withsoft-clipping. The density distribution is obtained by filtering the underlying image twice with a uniform filter which creates a heat map.

    The developed methods are evaluated by applying them on fabricated binary test images with known properties. The methods are very accurate when applied on simple test images but for more complex test images with greater variation the accuracy decreases. However, for most applications the results are still on an acceptable level.

  • 10.
    Al Kanale, Ahmed
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Investigation of recovery of stellar magnetic field geometries from simulated spectropolarimetric data2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Powerful remote sensing techniques can covert time variability of polarization profiles of stellar spectral lines into vector magnetic fields maps of stellar surfaces. These techniques are widely applied to interpret observations but have been tested using only simplistic tests. It would be of interest to test magnetic inversion methods using polarization spectra simulated for realistic and physical models of stellar magnetic fields provided by recent 3D numerical simulations. Doppler Imaging is a method to reconstruct vector magnetic field maps of stellar surfaces from variation of polarization profiles. The work in this thesis presents numerical experiments to evaluate the performance of Magnetic Doppler Imaging (MDI) code INVERS10. The numerical experiments showed that in given high-resolution observations in four Stokes parameters, the code is capable of reconstructing magnetic field vector distributions, over the stellar surface, simultaneously and without any prior assumptions about the magnetic field geometry. Input data consists of polarization measurements in the line profiles and the reconstruction is performed by solving the regularized inverse problem. Right results were obtained by testing different type of models covering simple, complex and unusual complex magnetic field distribution. Whilst using incomplete Stokes parameter datasets containing only Stokes I and V profiles, the INVERS10 code was able to reconstruct a global stellar magnetic fields of only simple models and give accurate and reliable results. Testing the code with different inclination and azimuth angle successfully gave the lowest deviation when same values are used from the true map.

  • 11.
    Alex, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Optimization of RIA-calculations: Simulating Falling Control Rods at Forsmark Nuclear Power Plant2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report accounts for investigations of ways to reduce the calculation times forsimulations of falling control rods in boiling water reactors done prior to everyreactor startup, known as RIA-calculations. Two methodologies to lower thecalculation times have been proposed, developed and implemented in a set ofmatlab-scripts, which are fully compatible with the previously used methodology.The new methodologies have been applied on 17 authentic power cycles at the threeForsmark reactors, whereby a reduction in calculation times by 70 to 90 % could bedemonstrated while still confidently maintaining the analysis performance. Thesimulations made and the basis of the new methodologies are described in detail inthis report, and possible steps to further lower the calculation times are alsoproposed.

  • 12.
    Alexandersson, Ilona
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Comet Ion Tail Observations Far From the Nucleus2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    On may 1, 1996, Ulysses spacecraft crossed the ion tail of comet Hyakutake, revealing an ion tail length of more than 3 times the Sun-Earth distance. The signatures of an ion tail, especially the ion tail far from the nucleus, are not well explored and many question marks remain. This report summarizes previous observations of spacecraft - ion tail crossings and what signatures that can be expected, as well as signatures of other known solar wind structures. A data analysis is made of possible ion tail encounters from Rosetta spacecraft measurements, Ulysses spacecraft measurements and Earth-orbiting spacecraft measurements. A search from Venus Express data to detect ion tails of sungrazing comets is presented.

  • 13.
    Al-Husseiny, Zeid
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Energy Efficient LTE Site Operation: with Antenna Muting and dynamic Psi-Omni2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To allow access to the network at all times a base station has to continuously stay active. While being active, a base station does not usually transmit data constantly. Typically, the base stations either send out lots of data or barely anything at all, yet, the network is actively drawing power the whole time. Succeeding in lowering the power consumed when the data rate is often so low would therefore lead to great benefits, both economically and environmentally, as well as new prospects of innovation in engineering. The process of how to dynamically change from a capacity optimized mode to an energy optimized mode as well as when to do this change is studied in this thesis for LTE.

    By using methods such as antenna muting and psi-omni coverage, the power consumption can decrease. These solutions however also decreases performance, and has to be activated with great care in mind not to cause any major impact on user performance. The dynamic configuration is dependent on the load of the system, changing to an energy efficient mode when traffic is low and to a capacity optimized mode when the network needs to supply high data rates.

    Simulations show that most energy savings can be found in rural and urban environments. Dynamic antenna muting achieved, summarizing macro environments, 24.9% energy savings with 95.27% downlink data rates compared to the reference case of using sector mode continuously i.e MIMO. In the same environments, dynamic psi-omni coverage together with antenna muting achieved energy savings of 43.8% with 89.3% downlink data rates compared to typical sector mode. Traffic rates are based on future demands in Europe by 2015, assuming that 20% of the subscribers are downloading 900 MB/h and the other 80% subscribers, at 112.5 MB/h. 

  • 14.
    Almquist, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Numerical wave propagation in large-scale 3-D environments2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    High-order accurate finite difference methods have been applied to the acoustic wave equation in discontinuous media and curvilinear geometries, using the SBP-SAT method. Strict stability is shown for the 2-D wave equation with general boundary conditions. The fourth-order accurate method for the 3-D wave equation has been implemented in C and parallelized using MPI. The implementation has been verified against an analytical solution and runs efficiently on a large number of processors.

  • 15.
    Amanda, Nordhamn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Design and implementation of a demonstrator for a Bluetooth Low Energy based fleet service system for hand-held gardening and forestry products2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today, large companies specialized in forestry or park maintenance may own very large machine fleets consisting of hundreds of trimmers, chainsaws and brush cutters. Husqvarna Group, whose core business lies within high-end forestry and gardening products, has noticed that such companies tend to buy cheaper, low quality forestry and gardening products. The reason is thought to be that the companies lack a proper overview of the service status and utilization levels of their machines, leading to insufficient service, causing machines to break prematurely and making it hard to motivate investments in more expensive products. Hence, the companies usually adopt a consumerist approach, and buy cheaper products that are thrown away upon breaking.

    To make their products more attractive to machine park owners, Husqvarna want to explore the area of Internet of Things and equip their machines with sensing and communication capabilities. Collected data could be used to provide an overview of machine usage and service requirements to the machine parks owners, and could make it easier for machine park owners to dimension their machine fleet. In addition to this, a machine monitoring system where specific operator behavior can be tracked could enable identification of operators who consistently mistreat their machines by, for example, running the machine engine at non-optimal rotation speeds.

    In this master's thesis, a demonstrator of the working principle of a Bluetooth Low Energy based Fleet Service System is designed and implemented, complete with an evaluation of if received signal strength indicator (RSSI) is a good enough distance estimator to determine which operator operates a certain machine. 

    Experiments carried out indicate that while RSSI is not a good estimator of distance, it could be used to determine the operator in closest proximity given that operators are not allowed to work closer than within a 10 m radius of each other.

  • 16.
    Anbo, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Identification of extreme load cases for a surface drill rig by means of MBS simulations2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis is Atlas Copco Craelius’ first step in incorporating numericalmethods in load case analysis during the development process. Atlas Copco needs toconstantly evolve and refine their methods in the design process to remain as thenumber one manufacturer of mining and construction equipment. Poor knowledge ofloads results either in structural failures or in oversized structures, both very costlyfor Atlas Copco.The main goal of this thesis is to examine the potential in MBS software by using it toidentify extreme load cases in one of Atlas Copco Craelius’ surface drill rigs, Mustang5. The MBS-software ADAMS View is used to build a model of the Mustang 5 drill rigand evaluate simulation results. The rig model is subject to motions which representreal case scenarios. The feed positioning possibilities are examined thoroughly since it was expected that the positioning has impact on the load levels. 25 different feedpositioning are simulated.The main conclusion is that the load levels are highly dependent on the feedpositioning. For example, the load levels in the boom raising cylinder can increaseseven times, if the rig is operated with the most unfavorable positioning compared tothe recommended. It could also be concluded that not only one positioning isextreme in terms of loads; it depends on which part of the boom system is beingobserved. Thus, several positioning cases have to be taken into consideration in orderto optimize the design of parts in the boom system.

  • 17.
    Andersson, Axel
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Optimized Tuning of Parameters for HVDC Dynamic Performance Studies2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    HVDC (High Voltage Direct Current) is used all over the world for transmission of electric power due to lower losses compared to traditional HVAC (High Voltage Alternating Current). However, the procedure of converting AC into DC puts great demand on the control system of the converter stations. These control systems need to be tuned properly to give the HVDC system the correct dynamics to handle variations in the network load and other disturbances. In this thesis, it was investigated if optimization algorithms can be used for tuning of the control parameters. Focus was on three parts of the control system, the Current Control Amplifier, Voltage Dependent Current Order Limiter and the Rectifier Alpha Minimum Limiter. The Nelder & Mead Simplex method was used and several different objective functions were tested, including combinations of integral square error, integral absolute error, rise time and overshoot. Several different fault cases and scenarios were tested and results of the optimization were compared to the manually tuned control system. It was found that the results of the optimization were comparable with the manually tuned parameters for many of the cases tested. The biggest issue encountered was that the optimization algorithm often finds a local minimum in the objective function, leading to a suboptimal solution. This issue could be solved by running the optimization several times, using different initial values. It is concluded that using optimization algorithms could be a useful tool for tuning of the HVDC control system.

  • 18.
    Andersson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Mathematical Optimization of Radiation Therapy Goal Fulfillment2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cancer is one of the deadliest diseases today, and with increasingly larger and older populations, cancer constitutes an enormous contemporary and future challenge. Luckily, advances in technology and medicine are continuously contributing to a decrease in cancer mortality, and to the reduction of treatment side effects. The aim of this Master's thesis is to be a part of these advances, thereby increasing the survival chances and well-being of future cancer patients.

    The thesis regards specifically the improvement of radiation therapy, a form of treatment utilized in both curative and palliative cancer care. In radiation therapy, ionizing radiation is directed at cancerous cells in the body. The radiation prevents the further proliferation of malignant cells by damaging their DNA. However, the radiation is also harmful to healthy cells. It is therefore of utmost importance that the irradiation of the patient is done in such a way to spare the critical organs in the vicinity of the tumor.

    To obtain the best possible treatment, mathematical optimization algorithms are utilized. Using physical models of how radiation travels in the body, it is possible to calculate what effect the irradiation of the patient will have. To quantify the quality of the treatment, mathematical functions are used, which evaluate the radiation dose under certain criteria. Once these functions are defined, algorithms can be applied that find the optimal treatment with regard to the given criteria.

    The formulation of these functions and their properties is the main focus of this thesis. Using clinical evaluation criteria previously used to assess treatments, a framework for optimizing functions that directly correlate to the clinical goals is constructed. The framework is examined and used to generate radiation therapy plans for three cancer patients. In each of the cases, the constructed treatment plans demonstrate high quality, often better than or comparable to the plans created by experienced dose planners using existing tools.

    A particularly interesting application of the developed framework is the automatic generation of treatments. This relies on the clinician giving the clinical goals as input to the algorithm. A plan is then generated with maximal goal fulfillment. This eliminates the tedious and time consuming process of parameter tuning to achieve a satisfactory plan. Several studies have demonstrated the ability of automatic planning to retain the plan quality while substantially improving planning efficiency.

  • 19.
    Andersson, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction.
    Seamless Automatic Projector Calibration of Large Immersive Displays using Gray Code2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Calibrating multiple projectors to create a distortion free environment is required in many fields e.g. simulators and the calibration may be done in a series different ways.

    This report will cover an automatic single camera projector calibration algorithm.The algorithm handles multiple projectors and can handle projectors covering bigger field of view than a camera by supporting image stitching. A proof of concept blending algorithm is also presented. The algorithm includes a new developed interpolation method building on spline surfaces and an orientation calculation algorithm that calculates the orientation difference between two camera views.

    Using the algorithm to calibrate, gives pixel accuracy of less than 1 camera pixel after interpolation and the relation between two views are calculated accurately. The images created using the algorithm is distortion free and close to seamless.

    The algorithm is limited to a controlled projector environment and calibrates the projectors for a single viewpoint. Furthermore, the camera needs to be calibrated positioned in the sweet spot although it can be arbitrary rotated.

  • 20.
    Andersson, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Individualized mathematical modeling of neural activation in electric field2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Deep Brain Stimulation (DBS) is a treatment of movement disorders such as Parkinson's disease and essential tremor. Today it has been used in more than 80.000 patients. Electrical stimulation is administered by an implanted pulse generator through an electrode surgically placed in a target brain area specific to the treated disease. Opposed to alternative purely surgical treatment procedures, DBS is reversible and can be turned off.

    In this project, the aim is to individualise an already existing computational model of DBS, but also to look at optimisation of the treatment by developing a neuron model. It has been executed the following way. To localise the target area for the electrode, Magnetic Resonance Imaging (MRI) is used. An MRI image consists of volume elements called voxels. By analysing these voxels, it is possible to set up a coordinate system for the position of different parts of the brain. To build up an individualised model of the DBS, an MRI image is segmented into tissues of different conductivity thus resulting in a more accurate description of the electrical field around the electrode. To visualize the stimuli coverage for the medical staff, the MRI image of the target area, the electrode, and the electrical field produced by the stimuli are depicted in the same figure. From the results, we can draw the conclusion that this method works well for individualising the computational model of DBS, but it has only been used on one MRI scan so far so it needs further testing to obtain more data to compare with.

    The neuron model is a temporospatial mathematical model of a single neuron for the prediction of activation by a given electrically applied field generated by a DBS lead. The activation model is intended to be part of a patient-specific model of an already existing computational model of DBS. The model originate from a neuron model developed by Hodgkin and Huxley (HH). The original HH model only takes into account one compartment and, to make the neuron model more accurate, it is combined with a cable model. The simulation results obtained with the model have been validated against an established and widely accepted neuron model. The results correlated highly to each other with only minor differences. To see how position and orientation impact on activation, the developed HH model was tested for different pulse widths, distances from the lead, and rotations of the neuron relative to the lead. A larger pulse width makes activation more likely and so does a larger amplitude. Thicker neurons are more likely to get activated, neurons closer to the lead and also neurons perpendicular to the lead. From the results we can draw the conclusion that this method is a good way to stimulate neural activation of a single neuron. In future research, it might be possible to compare results from the neuron model with patient's response to treatment.

  • 21.
    Andersson, Jonathan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Radiology.
    Methods for automatic analysis of glucose uptake in adipose tissue using quantitative PET/MRI data2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Brown adipose tissue (BAT) is the main tissue involved in non-shivering heat production. A greater understanding of BAT could possibly lead to new ways of prevention and treatment of obesity and type 2 diabetes. The increasing prevalence of these conditions and the problems they cause society and individuals make the study of the subject important.

    An ongoing study performed at the Turku University Hospital uses images acquired using PET/MRI with 18F-FDG as the tracer. Scans are performed on sedentary and athlete subjects during normal room temperature and during cold stimulation. Sedentary subjects then undergo scanning during cold stimulation again after a six weeks long exercise training intervention. This degree project used images from this study.

    The objective of this degree project was to examine methods to automatically and objectively quantify parameters relevant for activation of BAT in combined PET/MRI data. A secondary goal was to create images showing glucose uptake changes in subjects from images taken at different times.

    Parameters were quantified in adipose tissue directly without registration (image matching), and for neck scans also after registration. Results for the first three subjects who have completed the study are presented. Larger registration errors were encountered near moving organs and in regions with less information.

    The creation of images showing changes in glucose uptake seem to be working well for the neck scans, and somewhat well for other sub-volumes. These images can be useful for identification of BAT. Examples of these images are shown in the report.

  • 22.
    Andersson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Industrial Engineering & Management.
    Development of models for quantifying the environmental impact of demand response in electrical power distribution2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report some possible consequences of introducing demand response in the electric power grid are studied. Demand response is a part of the Smart Grid, which is a technology being developed to use our electric power grids more efficiently. Demand response programs aim to move people’s power usage over different times of the day, for example to distribute the power usage more evenly throughout the day or to permit a larger share of renewable, intermittent power sources in the system without making the delivery of electric power less stable.  A distribution system operator (DSO) can encourage customers to shift their power usage between different hours by various tariffs, for example by using time-differentiated or power dependent tariffs.

     

    In this thesis, the change in power losses and possible environmental impact of introducing due to a power shift is studied. Power input curves from a DSO, Sala-Heby Energi AB, are studied and modified to simulate a power shift with an evened out electric power usage. The studies made show that in the best-case scenario, that is a electric power usage evened out to 100% each day, the power losses in the whole grid can be reduced with 2.6%. The environmental study shows that the result varies greatly with what method is chosen to do the calculations. The results are presented in kg CO2-equivalents (CO2e), and depending on method used they can either decrease or increase. The environmental study show that the environmental impact from the power usage is more dependent on the shift in power usage between hours than the decrease in electric power losses. 

  • 23.
    Andersson, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Investigations of domain-wall motion using atomistic spin dynamics2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, current driven domain-wall motion is studied using atomistic simulations with the exchange coupling modeled by the Heisenberg Hamiltonian under the nearest-neighbor approximation. The investigations may be divided into two parts, each concerned with how different aspects of the systems affect the domain-wall motion. The first part deals with domain-wall width dependence of the velocity in a three dimensional geometry with simple cubic crystal structure and uniaxial anisotropy. Results from this part showed that the velocity has a minor domain-wall width dependence. For a fixed current density, the velocity increased with domain-wall width, though only from 61.5 a/ns to 64.5 a/ns as the domain-wall width was increased from 3 to 25 atoms.

    The second part of the investigations deals with phenomena involving mixed cubic and uniaxial anisotropy, the non-adiabaticity parameter as well as the geometry of the system. The discussion includes an account of how the spin-transfer and cubic anisotropy torques contribute to the motion for different values of the non-adiabaticity parameter. In comparing a one dimensional atomic chain and a three dimensional system with simple cubic crystal structure, but otherwise with the same material properties, results showed a difference in how the two systems responded to currents. This difference is not accounted for by the micromagnetic theory, and its origin was unable to be determined.

  • 24.
    Appelgren, Filiph
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Power System Software Development: with possible SCADA System Integration2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order for power system operators (such as TRANSCO) to maintain and operatethe transmission grid in a safe, secure and effcient way, automatic tools such asSCADA systems is necessary to meet demand at all times. The main purpose of thisthesis was to develop a software/prototype at the load despatch centre at TRANSCOwith the ability to monitor and communicate with power plants. The software issupposed to work in a real-time electronic market. The power plant operators candeclare their availability and capability parameters of their generating and producingunits to TRANSCO and LDC operators can send load despatch instructions to thepower plants (such as load changes and other ancillary instructions). The prototypealso has a compliance monitoring application that validates unit outputs againstdespatched instructions. If the output is outside a specific interval, a transgressionwarning is sent to the power plant informing them that they should adjust their unitoutput against the target load. If further transgression is continued, the operator atLDC can re-declare the units availability on the power plants behalf and issue a newload despatch instruction to the unit. The re-declared availability level will be valid allthe way back to when the unit issued the last availability declaration.The software was successfully developed and could perform all tasks that it wassupposed to in a satisfactory way. In order to make the development as sufficient andeffective as possible, a "dummy" power plant was created and was used to simulateunit outputs and plant operator behaviour. As the time was too short, the SCADAintegration was never investigated and was left to whom is taken over after this thesishas ended.

  • 25.
    Arfwedson, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Creating a usable analysis application built on an existing visualization platform2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The advances in research on wireless communications has lead up to the current success of 4G mobile broadband and is currently focusing on designing the upcoming even more advanced fifth generation (5G) networks. The type of research behind this typically generates large quantities of data and requires efficient analysis in order to achieve tangible results. To enable this analysis, visualization of the data is used to give the researchers the needed insights. For this master thesis project an existing platform will be analyzed with the goal of, by utilizing the platform, creating a powerful, useful analysis application with the necessary and desired tools. The platform can access data produced from research simulations and visualize them through different types of useful charts. However, it has up until now lacked some important functionality, mainly letting the user modify and alter the visualization to aid in the analysis. It furthermore requires knowledge and experience before being useful. To solve this, there existed a need of extending the platform with new tools and functionality to give the user more control and possibilities and to simplify the usage. The thesis resulted in a functioning analysis application that gives the user many necessary features to effectively analyze data. The result fulfilled the set requirements with improved and added views, extended tools and optimized performance.

  • 26.
    Arfwedson, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Improving eciency of EMC ImmunityMonitoring of RBS using a FPGA basedinstrument2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A test system for Immunity testing of Ericsson's LTE radiobase station (RBS) was built using a National Instruments(NI) PXI chassis tted with a vector signal transceiver (VST)module and a PC controller module. A program made in Lab-VIEW and MATLAB was run on the controller module in thePXI chassis. The tasks of the program was, on one hand, tocontrol the VST which was used to record the signal emittedfrom the RBS and on the other hand, to process the signal anddetermine its quality by acquiring the bits transmitted. Functionalityenabling the VST to transmit a given signal was alsoincluded in the program. The built system performed up toninety times faster than the old system but lacked turbo decodingnecessary to correctly determine bit error ratio (BER)and block error ratio (BLER). The performance of the systemleaves room for adding time consuming processes such as turbodecoding later on and by examining the undecoded bits the signalquality can still be measured. The program handles both1tx and 2tx signals.

  • 27.
    Astrid, Berghult
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computing Science.
    A practical comparison between algebraic and statistical attacks on the lightweight cipher SIMON2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the summer of 2013 NSA released a new family of lightweight block ciphers called SIMON. However they did not publish any assessment of the security of SIMON. Since then only a few papers on this topic have been released and none of them have included an algebraic analysis. Moreover only one paper described a practical implementation of the attack. This master thesis aims to implement a practical attack, both algebraic and differential, on SIMON. In doing so we are able to make a comparison between the two different attack methods. The algebraic attack was executed with SAT-solver CryptoMiniSat2 and could break 7 rounds. The differential attack was implemented in three steps. First we created a difference distribution table (DDT) and then we identified a differential by a search algorithm for the DDT. In the last step we designed a key recovery attack to recover the last round key. The attack could break 13 rounds for a 9 round differential. With a simple expansion on the key recovery attack it has the potential to break even more rounds for the same 9 round differential. This indicate that algebraic cryptanalysis might not be such a strong tool since it could only break 7 rounds. Furthermore, if a generic algebraic attack does not work on SIMON it has little or no chance of being successful on a more complex cipher. In other words this algebraic attack may serve as a benchmark for the efficiency of generic algebraic attacks.

  • 28.
    Augustsson, Louise
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction.
    Study and Analysis of Convolutional Neural Networks for Pedestrian Detection in Autonomous Vehicles2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The automotive industry is heading towards more automation. This puts high demands on many systems like Pedestrian Detection Systems. Such systems need to operate in real time with high accuracy and in embedded systems with limited power, memory resources and compute power. This in turn puts high demands on model size and model design. Lately Convolutional Neural Networks (ConvNets) have dominated the field of object detection and therefore it is reasonable to believe that they are suited for pedestrian detection as well. Therefore, this thesis investigates how ConvNets have been used for pedestrian detection and how such solutions can be implemented in embedded systems on FPGAs (Field Programmable Gate Arrays). The conclusions drawn are that ConvNets indeed perform well on pedestrian detection in terms of accuracy but to a cost of large model sizes and heavy computations. This thesis also comes up with a design proposal of a ConvNet for pedestrian detection with the implementation in an embedded system in mind. The proposed network performs well on pedestrian classification and the performance looks promising for detection as well, but further development is required.

  • 29.
    Axelsson, Joel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Industrial Engineering & Management.
    Optimerad elnätstariff för prosumenter2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis was to form a tariff that is economicallyadvantageous for owners of solar panels connected to the grid. On thepower distribution grid company Sala-Heby Energi Elnät AB practices atariff based on the avarage value of the five highest power peaks permounth on weekdays between 7 am to 7 pm. To investigate if anothertariff structure could be more economically advantageous for ownersof solar panels, three different types of tariff structures weretested; Power tariff, Energy tariff and Power combined with Energytariff. For all these, different parameters were changed and theprices were optimized by linear optimization. The data that was used,was collected from a representative selection of the availablehousehold costumers. Also data from available solar electricityproduction establishments was collected and virtual solar panels wasinstalled to the households, to investigate the savings of theinvestigated tariff structures. The conclusion was that an energytariff with a charged time between 9 am to 5 pm on weekdays and freehours during low load times of the days was the alternative that wasmost economically advantageous for costumers with solar panels. Inavarage, one could save 600 SEK during April-October with this tariffstructure. Though, this tariff can be disadvantageous for housholdcostumers and also imply an economical risk for SHE.

  • 30.
    Backlund, Ludvig
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computing Science.
    A technical overview of distributed ledger technologies in the Nordic capital market.2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis examines how Distributed Ledger Technologies (DLTs) could be utilized in capital markets in general and in the Nordic capital market in particular. DLTs were introduced with the so called cryptocurrency Bitcoin in 2009 and has in the last few years been of interest to various financial institutions as a means to streamline financial processes. By combining computer scientific concepts such as public-key cryptography and consensus algorithms DLTs make it possible to keep shared databases with limited trust among the participators and without the use of a trusted third party. In this thesis various actors on the Nordic capital market were interviewed and their stance on DLTs were summarized. In addition to this a Proof of Concept of a permissioned DLT application for ownership registration of securities was constructed. It was found that all the interviewees were generally optimistic about DLTs potential to increase the efficiency of capital markets. The technology needs to be adopted to handle the capital markets demand for privacy and large transaction volumes, but there is a general agreement among the interviewees that these issues will be solved. The biggest challenge for an adoption of DLTs seem to lie in that of finding a common industry-wide standard.

  • 31.
    Bahceci, Ertin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    High performance computing and visualization of football match results - from algorithms built up using methods from modeling complex systems2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The evaluation of football players during and after a football match is an important field of study for football trainers and also people in academia. In this project some of the achieved theoretical results are implemented. Scientific findings are put into a context where the broader general public is able to understand the research. The ultimate goal is to produce visualizations such that they can be integrated into an application called Twelve where an everyday user can access them.

  • 32.
    Bahceci, Mesut
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Simulation of an Electrical Machine: with superconducting magnetic bearings2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis investigates if there is an induction motor configuration that can be used with a flywheel energy storage system, that uses passve superconducting magnetic bearings (SMBs). The configurations should be able to be designed with induction motor building blocks that are commercially available. The method used to investigate this was simulations of different induction motor configurations in the finite element analysis software COMSOL.

    The simulations show that when larger air-gaps than that of a commercial IM unit are used it is possible to use SMBs in the IM. SMBs have the advantage of having zero resistance which makes it possible to store energy without resistance losses. However it was found that by using and IM with SMBs the generated power would be lower than that of a commercial unit.

  • 33.
    Barck, Ivan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Lind, Joar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Jansson, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Crowdfunding i start up-företag: En fallstudie om delägarbaserad crowdfunding som finansieringsmetod2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study was performed to examine the performance of an equity based crowdfunding campaign, as well as seeking to describe the risks, complications and the opportunities that this kind of funding brings. The study was conducted by an empirical case study of a company that was about to initiate an equity based crowdfunding campaign.

    The conclusion is that the planning of an equity based crowdfunding campaign is time consuming and requires knowledge in many different areas. Therefore it is important to identify in which areas skills and resources already are available within the company, and where it must be obtained through a learning process.

    The report also highlights that equity based crowdfunding, because of legal restrictions surrounding the issue of unlisted shares, can not be marketed as other types of crowdfunding. This leads to the conclusion that those who invest in equity based crowdfunding do not necessarily belong to the crowd that crowdfunding is generally associated with. Arguments can be made that this crowdfunding model rather resemble traditional angel networks.

    A technical study was also made about the company's products. The result of the technical study can be used by customers to get a clearer understanding of the company's products, but also by the company itself as a good insight into how their products work in practice and to develop the existing products.

  • 34.
    Barkefors, Annea
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    3D Synthetic Aperture Technique for Ultrasonic Imaging2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The group for non-destructive testing at Uppsala University has recently implemented the phase shift migration method, which is a method to focus images acquired unfocused using ultrasound. However, their work has been limited to 2D data, while for many applications the gathered data is 3D. This project has extended the old implementation to 3D data. The new implementation has been done in two different ways, giving one algorithm that works fast but needs much RAM, and one algorithm that takes long time but works on smaller computers, not demanding as much memory. The fast algorithm works faster than the time it takes to acquire the raw data, which makes real-time use realistic. To test the performance of the two algorithms with respect to image improvement, both against each other and against the previous 2D implementation, a number of experiments were carried out, which showed that, apart from processing time, the two new algorithms were equal in performance. The experiments also showed that the obtained resolution in both x- and y-directions matched the theoretical discussion.

  • 35.
    Barkino, Iliam
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Summary Statistic Selection with Reinforcement Learning2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Multi-armed bandit (MAB) algorithms could be used to select a subset of the k most informative summary statistics, from a pool of m possible summary statistics, by reformulating the subset selection problem as a MAB problem. This is suggested by experiments that tested five MAB algorithms (Direct, Halving, SAR, OCBA-m, and Racing) on the reformulated problem and comparing the results to two established subset selection algorithms (Minimizing Entropy and Approximate Sufficiency). The MAB algorithms yielded errors at par with the established methods, but in only a fraction of the time. Establishing MAB algorithms as a new standard for summary statistics subset selection could therefore save numerous scientists substantial amounts of time when selecting summary statistics for approximate bayesian computation.

  • 36.
    Bashir, Hussam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Calculation of Wave Propagation for Statistical Energy Analysis Models2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the problems of applying Statistical Energy Analysis (SEA) tomodels that include solid volumes. Three wave types (Rayleigh waves, Pressure wavesand Shear waves) are important to SEA and the mathematics behind them is explainedhere. The transmission coefficients between the wave types are needed for energytransfer in SEA analysis and different approaches to solving the properties of wavepropagation on a solid volume are discussed. For one of the propagation problems, asolution, found in Momoi [6] is discussed, while the other problem remains unsolveddue to the analytical difficulties involved.

  • 37.
    Bengtsson Bernander, Karl
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction.
    A Method for Detecting Resident Space Objects and Orbit Determination Based on Star Trackers and Image Analysis2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Satellites commonly use onboard digital cameras, called star trackers. A star tracker determines the satellite's attitude, i.e. its orientation in space, by comparing star positions with databases of star patterns. In this thesis, I investigate the possibility of extending the functionality of star trackers to also detect the presence of resident space objects (RSO) orbiting the earth. RSO consist of both active satellites and orbital debris, such as inactive satellites, spent rocket stages and particles of different sizes.

    I implement and compare nine detection algorithms based on image analysis. The input is two hundred synthetic images, consisting of a portion of the night sky with added random Gaussian and banding noise. RSO, visible as faint lines in random positions, are added to half of the images. The algorithms are evaluated with respect to sensitivity (the true positive rate) and specificity (the true negative rate). Also, a difficulty metric encompassing execution times and computational complexity is used.

    The Laplacian of Gaussian algorithm outperforms the rest, with a sensitivity of 0.99, a specificity of 1 and a low difficulty. It is further tested to determine how its performance changes when varying parameters such as line length and noise strength. For high sensitivity, there is a lower limit in how faint the line can appear.

    Finally, I show that it is possible to use the extracted information to roughly estimate the orbit of the RSO. This can be accomplished using the Gaussian angles-only method. Three angular measurements of the RSO positions are needed, in addition to the times and the positions of the observer satellite. A computer architecture capable of image processing is needed for an onboard implementation of the method.

  • 38.
    Berg, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Ice navigation with ice compressionin the Gulf of Finland2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Safe winter navigation is a hot topic. Not only is the traffic density increasing but theenvironmental considerations are also getting bigger. An oil leakage from a big oiltanker can be of catastrophic proportions in the wrong area and more trafficincreases the risk of an accident. A project that aims for safer winter navigation isSafeWIN. The aim of this project is to develop a forecasting system for compressiveice and thus make winter navigation safer.This thesis is part of above mentioned project and aims to investigate what influenceice compression and ice class has on winter navigation. Vessels are exclusivelyAFRAMAX size tankers sailing on Primorsk in the Gulf of Finland during 2006. Transitdata comes from AIS tracks recorded by the Swedish Maritime Administration. Adatabase with tanker transits has been created and this information is the source forthe studies in this thesis. Included in the database are wind data, ice particulars andtransit information such as speed, and time at different activities during the transit.Average values for a transit has been investigated for comparison and to get a pictureof an average transit.Velocity, waiting time and time with assisting icebreaker are parameters that arebelieved to show how a tanker performs in winter navigation. These parameters arecompared with ice compression and ice class separately to see if there is acorrelation. Ice compression has also been investigated for correlation towards windforce to see if stronger wind generates stronger compression.Using the velocity in different ice compressions an estimate of ice resistance that stemfrom ice compression has been extracted by means of Lindqvist’s formula.

  • 39.
    Berglund, Albin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Evolution of Cavity Tip Vortices in High-Pressure Turbines2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This degree project in applied physics studies the tip gap flows over the rotor blades of a high-pressure turbine. The rotor blade used in the study has an improved design that utilizes both a cavity tip and an uneven profiling to reduce turbine loss. The designed rotor blade is shown to admit a 21% lower leakage mass flow rate across the tip gap than a reference rotor blade with a flat tip. By studying the designed rotor blade using transient CFD, the flow field of the tip gap region has been studied through one blade passage. The flow field characteristics of particular interest are the leakage mass flow rate across the tip gap region, which is proportional to turbine loss, and the characteristic vortices that reside within the cavity tip. By using post-processing scripts, the leakage mass flow rate has been calculated for every time step across one blade passage, showing a strong time dependence. The characteristic vortices are found using two different vortex detection algorithms, and their respective vorticity magnitude is shown to depend on the leakage mass flow rate. The simulation shows that the vorticity magnitude is increasing above a threshold of leakage mass flow rate, and that it is decreasing under this threshold. This effect is shown to destabilize the leakage mass flow rate, increasing its amplitude over its period of one blade passage.