This master’s thesis project investigates the utilization of a low-cost hyperspectral (HS) imaging rig to identify and classify drought stress in pine plants. Drought stress is a widespread environmental challenge affecting global forestry, requiring more resources as the industry grows and global warming rises. This provokes a need for affordable, and efficient monitoring methods. HS imaging, with its ability to capture a wide range of spectral information, offers promising methods for quick and precise measurements of plant stress. The project methodology is comprised of redesigning an existing HS imaging rig, with the camera employing push-broom technology, to yield precise and consistent HS images. This involved exploring the camera’s spectral range, designing components to ensure consistent artificial lighting using blackbody radiation sources, and calibrating the HS camera for focal depth and aberrations like smile and keystone. Two experiments were conducted to obtain the data for pine stress detection, first for two binary categories: Control, and 100% Drought, and later introducing a third semi-drought category in the second experiment. The data analysis encompassed preprocessing the HS images to correct the lighting intensity distributions and normalization of pixel values. Accompanied by filtering, resampling spectral data, and feature extraction facilitating consistent drought identification, and data management. To identify stress patterns in pine plants and temporal decay rates, methods such as spectral reflectance analysis, various vegetation indices (VI), and statistical learning techniques like discriminant analysis and logistic regression were evaluated for distinguishing between stressed and healthy plants. The results demonstrate the accuracy of the HS imaging rig in measuring spectral reflectances from plants, capturing changes between 550 − 670 nm in the visible spectrum and 750 − 890 nm in the near-infrared (NIR) spectrum due to increasing stress affecting chlorophyll levels. Both well-established VIs and empirically designed indices indicate reliable early detection. Comparing multiple VIs to statistical learning models shows similar performances in binary classification tasks. Feature selection methods using correlation matrices, and L1 penalty for logistic regression support stress effects visible in the data, paving the way for cost-effective strategies in sustainable forestry management.

Magnetic resonance imaging (MRI) utilizes the magnetic properties of tissues to generate image-forming signals. MRI has exquisite soft-tissue contrast and since tumors are mainly soft-tissues, it offers improved delineation of the target volume and nearby organs at risk. The proposed Magnetic Resonance-only Radiotherapy (MR-only RT) work flow allows for the use of MRI as the sole imaging modality in the radiotherapy (RT) treatment planning of cancer. There are, however, issues with geometric distortions inherent with MR image acquisition processes. These distortions result from imperfections in the main magnetic field, nonlinear gradients, as well as field disturbances introduced by the imaged object. In this thesis, we quantified the effect of system related and patient-induced susceptibility geometric distortions on dose distributions for prostate as well as head and neck cancers. Methods to mitigate these distortions were also studied. In Study I, mean worst system related residual distortions of 3.19, 2.52 and 2.08 mm at bandwidths (BW) of 122, 244 and 488 Hz/pixel up to a radial distance of 25 cm from a 3T PET/MR scanner was measured with a large field of view (FoV) phantom. Subsequently, we estimated maximum shifts of 5.8, 2.9 and 1.5 mm due to patient-induced susceptibility distortions. VMAT-optimized treatment plans initially performed on distorted CT (dCT) images and recalculated on real CT datasets resulted in a dose difference of less than 0.5%.  The magnetic susceptibility differences at tissue-metallic,-air and -bone interfaces result in local B0 magnetic field inhomogeneities. The distortion shifts caused by these field inhomogeneities can be reduced by shimming.  Study II aimed to investigate the use of shimming to improve the homogeneity of local  B0 magnetic field which will be beneficial for radiotherapy applications. A shimming simulation based on spherical harmonics modeling was developed. The spinal cord, an organ at risk is surrounded by bone and in close proximity to the lungs may have high susceptibility differences. In this region, mean pixel shifts caused by local B0 field inhomogeneities were reduced from 3.47±1.22 mm to 1.35±0.44 mm and 0.99±0.30 mm using first and second order shimming respectively. This was for a bandwidth of 122 Hz/pixel and an in-plane voxel size of 1×1 mm2.  Also examined in Study II as in Study I was the dosimetric effect of geometric distortions on 21 Head and Neck cancer treatment plans. The dose difference in D50 at the PTV between distorted CT and real CT plans was less than 1.0%. In conclusion, the effect of MR geometric distortions on dose plans was small. Generally, we found patient-induced susceptibility distortions were larger compared with residual system distortions at all delineated structures except the external contour. This information will be relevant when setting margins for treatment volumes and organs at risk.   The current practice of characterizing MR geometric distortions utilizing spatial accuracy phantoms alone may not be enough for an MR-only radiotherapy workflow. Therefore, measures to mitigate patient-induced susceptibility effects in clinical practice such as patient-specific correction algorithms are needed to complement existing distortion reduction methods such as high acquisition bandwidth and shimming.

In this project a qutrit tripod system is studied to implement quantum gates using non-Abelian geometric phases, allowing for holonomic quantum computation which in turn results in more robust computations. First, a general foundation of the theory is presented. This includes the relevant theory of matrices in Hilbert space, as well as theory of the quantum mechanics used in the report. The method is then described in depth, showing how the pulse area is fixed. Using properties of the Hamiltonian as well as the time-evolution operator of the tripod system the computational subspace can be derived. These findings are combined to show how the computational subspace evolves in time, resulting in the unitary matrix used to form quantum gates. Using educated guesses to find the necessary parameters or utilizing iterative methods to find the parameters are the two main approaches used for constructing the considered gates. Three of the suggested quantum gates are successfully implemented through educated guesses, namely X, T and Z using an angle parametrization of the phase and amplitude of the pulses. The last desired gate is the Hadamard-gate, but the implementation of said gate required numerical approximation. The reasons as to why this is the case, are later discussed.

No description available.

Energy resolution characteristics of silicon surface barrier detector signals amplified by different preamplifiers and spectroscopic amplifiers have been studied. The characterization has been done using alpha particles from an 241Am source and spontaneous fission fragments from two Cf sources. The alpha and spontaneous fission activities of the sources have been measured and the isotopic compositions, ages, and initial activities of the two Cf sources have been calculated using the results from the activity measurements. 82.3% and 82.5% of the spontaneous fission activity of the two sources is found to originate from 252Cf. Heavy ion detection properties of two Si detector setups have been determined by measuring spontaneous fission fragments from one of the Cf sources in coincidence. The mass distribution of fission fragments is derived from the pulse spectra of the coincidence measurements. The conditions for future time resolution measurements have been established. Inquiries on commercially available ultra-thin Si detectors have been made. The purpose is to upgrade detector telescopes to lower the energy threshold of ΔE-ΔE-E identification of particles from neutroninduced nuclear reactions. Three manufacturers of Si detectors with thickness 20-25 µm and active area around 450 mm2 have been listed together with properties of the three offered detectors.

This thesis uses theoretical studies, and numerical simulations to provide results of the experimental reach to detect the QCD axion as dark matter in a Non-standard cosmological background. Assuming that the QCD axion constitutes the full CDM abundance of the universe, this thesis elaborates on its potential detection from experimental setups for the mass window of the axion. The set of results that is obtained here are the relic CDM energy density of axions produced by the vacuum realignment mechanism and the CDM energy density of axions produced from the decay of a network of cosmic strings. This thesis provides results regarding the possibility to detect a primordial gravitational wave relic, which is possible within some favorable cosmological scenarios for the background.

A black body is an ideal object that absorbs all incident electromagnetic radiation and simultaneously emits radiation that only depends on the temperature. The radiation is described by Planck's radiation law and its maximum by Wien's displacement law. The aim of this project is to study Planck's and Wien's laws in the frequency and wavelength domains, by theoretical studies and numerical studies in the programming language Python. Planck's law can be derived by regarding a cavity where the internal radiation either can be regarded as waves or as a gas of photons. In this study, the main focus lies in the derivation assuming radiation can be treated as waves, which uses the Maxwell-Boltzmann distribution. This derivation is also used when the radiation is simulated numerically in Python. The numerical studies use the stochastic method "hit and miss" to generate the different properties of the emitted radiation. Planck's law occurs in many different forms, the differences between some of them is explained in this project. When transforming between the domains one must use a Jacobian. If this is forgotten Wien's law, which is derived from Planck’s law, efficiently shows how the peaks of the correct and the transformed curves are at different positions. The results show that Planck's law accurately can be derived numerically. Even though the chosen method successfully reproduces the Planck distribution the program can be improved by using the inverse transform method for sampling. To study this subject further one could consider deriving and simulating the Maxwell-Boltzmann distribution. / En svart kropp är intressant att undersöka på grund av dess unika förmåga att absorbera och emittera elektromagnetisk strålning. Dessvärre kan den svarta kroppen vara svår att föreställa sig. Det vedertagna knepet för att illustrera detta fenomen är att tänka sig en låda inuti vilken det finns fotoner, och därmed energi. Fotoner kan som bekant betraktas som vågor likväl som partiklar och turligt nog spelar det ingen roll vilket sätt man väljer, svartkroppsstrålningen kan studeras ur båda dessa infallsvinklar. Tänker man sig också att det finns ett mycket litet hål i lådans vägg är det lätt att inse att fotonerna kommer att lämna lådan ur detsamma. Det är denna strålning som är svartkroppsstrålning. Svartkroppsstrålningen är fördelad enligt Plancks strålningslag som vanligtvis härleds med hjälp av teorin kring statistisk fysik som appliceras på den tänkta lådan. Detta görs även i denna studie, såväl som en numerisk simulering i programmeringsspråket Python. Ett program för studier av svartkroppsstrålning, vars främsta syfte är att simulera denna med utgångspunkt i samma låda, har skapats och förväntas kunna hjälpa den intresserade att skaffa sig förståelse för egenskaperna hos Plancks lag. För detta program används med framgång den stokastiska metoden "hit and miss" som tillåter användaren att sampla slumptal från en given fördelning. Utöver Plancks lag studeras också Wiens lag. Wiens lag beskriver vid vilken frekvens strålningen kommer att ha sitt maximum och härleds ur Plancks lag. Plancks lag förekommer i många olika former vilka beskriver olika fysikaliska storheter. I denna studie utreds dessa. Att transformera mellan de olika formerna av lagen är inte så simpelt som man kan luras att tro, utan kräver viss matematisk eftertanke. Det visar sig vara avgörande att använda en mycket viktig transformationsfaktor kallad Jacobian. Detta ger såklart också konsekvenser för Wiens lag som kommer att se olika ut beroende på vilken form av Plancks lag den härleds ur.

Predicting terrain trafficability of deformable terrain is a difficult task with applications in e.g, forestry, agriculture, exploratory missions. The currently used techniques are neither practical, efficient, nor sufficiently accurate and inadequate for certain soil types. An online method which predicts terrain trafficability is of interest for any vehicle with purpose to reduce ground damage, improve steering and increase mobility. This thesis presents a novel approach for predicting the model parameters used in modelling a virtual terrain. The model parameters include particle stiffness, tangential friction, rolling resistance and two parameters related to particle plasticity and adhesion. Using multi-body dynamics, both vehicle and terrain can be simulated, which allows for an efficient exploration of a great variety of terrains. A vehicle with access to certain sensors can frequently gather sensor data providing information regarding vehicle-terrain interaction. The proposed method develops a statistical model which uses the sensor data in predicting the terrain model parameters. However, these parameters are specified at model particle level and do not directly explain bulk properties measurable on a real terrain. Simulations were carried out of a single tracked bogie constrained to move in one direction when traversing flat, homogeneous terrains. The statistical model with best prediction accuracy was ridge regression using polynomial features and interaction terms of second degree. The model proved capable of predicting particle stiffness, tangential friction and particle plasticity, with moderate accuracy. However, it was deduced that the current predictors and training scenarios were insufficient in estimating particle adhesion and rolling resistance. Nevertheless, this thesis indicates that it should be possible to develop a method which successfully predicts terrain model properties.

In this work, regression models for the wake field entering a propeller at certain axial andnominal position have been proposed. Wakes are non-uniform flows following a body immersedin a viscous fluid. We have proposed models for the axial and tangential velocity distribution asfunctions of ship hull and propeller measures. The regression models were modelled using Fourierseries and parameter estimations based on skewed-Gaussian and sine functions. The wake fieldis an important parameter in propeller design. The regression models are based on experimentaldata provided by the Rolls-Royce Hydrodynamic Research Center in Kristinehamn. Also we havestudied the flow in the axial velocity distribution in the propeller plane using the coherent structurecoloring method. The coherent structure coloring is used to study coherent patterns by looking atfluid particle kinematics. Using this type of analysis, we observed that the velocity distributionbehaves kinematically similar in the different regions of the wake distribution, which according tothe coherent structure coloring indicate coherence. / I det här arbetet, har regressionsmodeller för medströmsfältet in i en propeller vid viss axielloch nominell position utvecklats. Medströmsfältet är ojämn strömning efter en kropp nedsänkt i enviskös vätska. Vi har föreslagit modeller för axiell och tangentiell hastighetsfördelning som funktionerför fartygsskrov-och propeller-parametrar. Regressionsmodellerna modellerades med hjälpav Fourier-serier och parameterskattning baserade på skeva Gaussfördelningar och sinusfunktioner.Medströmsfältet är en viktig parameter i propeller design. Regressionsmodellerna är baserade påexperimentella data från Rolls-Royces Hydrodynamiska Forskningscenter i Kristinehamn. Vi harockså studerat flödet i axialhastighetsfördelningen i propellplanet med hjälp av den koherenta struktureringsfärgmetoden.Den koherenta struktureringsfärgmetoden används för att studera koherentamönster genom att titta på vätskepartikelkinematik. Med hjälp av denna typ av analys observeradevi att hastighetsfördelningen uppför sig kinematiskt lika i de olika regionerna i medströmsfältet,vilket enligt koherenta strukturfärgmetoden indikerar koherens.

The Swedish energy power system is in the middle of a paradigm shift where the increased share of intermittent energy sources place higher demand on the ability to regulate and balance the generation and consumption of electricity. Demand flexibility, which means that consumers can adjust their energy consumption, is a promising solution to manage the imbalance in the power system. Electric heat pumps in residential buildings are recognized to have potential to serve as a flexible load. In this thesis, an aggregated multi-family residential building model is developed to generate heat load profiles for a larger number of buildings which facilitate an assessment of the heat pump flexibility. The flexibility assessment is performed for a local distribution grid area with 174 buildings and an electricity price region in Sweden with 10 146 buildings with heat pumps. The flexibility assessment analyses the heat pump load deviation between a base load case and a case where the heat pumps receive an off-signal. The assessment takes into consideration seven flexibility parameters and is conducted for ambient temperatures between -20°C and 15°C. The thermal inertia of multi-family residential buildings facilitates a load shift with a duration of 4.4 to 9.8 hours depending on the ambient temperature. The maximal average power reduction for one hour of 10 MW in a distribution grid and 169 MW in an electricity price region illustrates the potential of using heat pumps as a demand flexibility solution in the electricity grid.