During X-ray examinations a large part of the radiation is scattered from the patient, contributing to larger radiation doses to medical staff operating inside the examination room. Ionizing radiation contributes to the risk of developing cancer and hereditary diseases but also to the risk of developing cataract.   The aim of this thesis was to investigate the radiation environment and construct three-dimensional maps of the dose distribution, in a Computed Tomography (CT) room during examinations.    Air kerma was measured with real time dosimeters while irradiating an anthropomorphic phantom, using the X-ray tube voltages 100, 120 and 140 kV. The effective dose received by protected and unprotected medical staff inside the CT room during radiation exposure was estimated by using spectra from scattered X-ray radiation, a simulation of X-ray spectra and the dose evaluation program PCXMC. The equivalent dose to the eye lens was estimated by using spectra from scattered X-ray radiation and tabulated conversion factors from air kerma to the personal dose equivalent at 0.07 mm depth, Hp(0.07). From the estimated values of the effective dose and equivalent eye lens dose received by medical staff inside the room, three-dimensional dose distribution maps were constructed. The shielding effectiveness of a lead apron regularly used in the room was examined using tube voltages of 100, 120 and 140 kV.   The radiation dose distributions have a maximum closest to the irradiated phantom for most heights except at eye level where the maximum is shifted outwards along the patient table due to strong shielding by the gantry at eye level. The strong shielding of the gantry is noticed for all energy levels and at all heights but is exceptionally noticeable at eye level. The shielding of the patient table is strongest for the lower heights but is also noticeable at eye level which may seem surprising since there were no objects between the phantom and that point. The dose distribution along directions with minimal shielding seems to follow the inverse square law well. The lead apron is effective but its efficiency decreases for higher photon energies which is expected.   From information about the frequency and durations of CT-guided procedures, the estimated annual effective dose is 1.6-2.3 mSv for protected and 14.3-19.8 mSv for unprotected personnel at the operator position. The estimated annual equivalent eye lens dose is 4.7-7.8 mSv at the operator position. All annual doses at the operator position are below the annual threshold values of 20 mSv set by the ICRP.

No description available.

Quantum computing is a young but intriguing field of science. It combines quantum mechanics with information theory and computer science to potentially solve certain formerly computationally expensive tasks more efficiently. Classical computers are based on bits that can take on the value zero or one. The values are distinguished by voltage differences in transistors. Quantum computers are instead based on quantum bits, or qubits, that are represented physically by something that exhibits quantum properties, like for example electrons. Qubits also take on the value zero or one, which could correspond to spin up and spin down of an electron. However, qubits can also be in a superposition state between the quantum states corresponding to the value zero and one. This property is what causes quantum computers to be able to outperform classical computers at certain tasks. One of these tasks is searching through an unstructured database. Whereas a classical computer in the worst case has to search through the whole database in order to find the sought element, i.e. the computation time is proportional to the size of the problem, it can be shown that a quantum computer can find the solution in a time proportional to the square root of the size of the problem. This report aims to illustrate the advantages of quantum computing by explicitly solving the classical Windows game Minesweeper, which can be reduced to a problem resembling the unstructured database search problem. It is shown that solving Minesweeper with a quantum algorithm gives a quadratic speedup compared to solving it with a classical algorithm. The report also covers introductory material to quantum mechanics, quantum gates, the particular quantum algorithm Grover's algorithm and complexity classes, which is necessary to grasp in order to understand how Minesweeper can be solved on a quantum computer.

Westinghouse Electric Sweden AB’s three-dimensional reactor core simulation program POLCA uses a large number of tables containing various fuel dependent data, such as cross sections, pin power maps with power distribution etc. POLCA uses quadratic and linear interpolation to extract the values needed for the simulation. However, finding the correct values to interpolate between takes time. This master thesis describes a method of compacting the tables by removing values, in order to shorten the needed simulation time. This is done so that no significant accuracy is lost in the interpolations. The method also finds deviant values and replaces these with new, interpolated values. The thesis shows that approximately 90 % of all values can be removed without losing significant accuracy. These results are however heavily dependent on the choice of accuracy loss criterion; a lower allowance for accuracy loss lowers the amount of values which can be removed sharply.

Den roterande bäddreaktornSpinChem® RBR S2 kan fyllas med solida partiklar och sänkas ned och roteras ien vätska. Detta gör att kemiska reaktioner mellan vätskan och partiklarna iRBR:en kan äga rum.Flödet från en RBR S2 i en 76 dm3 stor vattentank undersöktes med hjälp avsimuleringar i ANSYS Fluent 18.0. Den tid som krävdes för ett färgämne attsprida sig jämnt i vattentanken på grund av flödet från RBR:en mättes i ettexperiment och jämfördes med motsvarande simuleringar. Mixningstiderna frånexperimentet visade att det krävdes i genomsnitt 161 s för färgämnet att blijämnt fördelat, medan simuleringarna överskattade denna tid med ungefär 89 %.En simuleringsmodell för att avgöra hur mycket av en vätska som varit i kontaktmed partiklarna i RBR:en efter en given tid togs fram och testades.Simuleringarna visade att ungefär 8660 s krävdes för att 95 % av vätskan ivattentanken skulle ha varit i kontakt med partiklarna. Denna tid verifieradesdock inte med experiment. / The rotating bed reactorSpinChem® RBR S2 can be filled with solid particles and submerged into a liquidwhere it is rotated, which allows for chemical reactions to occur between theliquid and the particles.The flow in a 76 dm3 large tank of water due to the rotating RBR S2 wasinvestigated using simulations performed in ANSYS Fluent 18.0. The timerequired for a colouring agent to become uniformly mixed in the tank due to theflow from the device was measured in a practical experiment and was compared tosimulations. The mixing times obtained in the practical experiment were onaverage approximately 161 s, whereas the times obtained in the simulationoverpredicted this with approximately 89 %.A simulation model for determining how much of a liquid has been in contactwith the particles in the RBR after a given amount of time was suggested andtested. The simulation results showed that approximately 8660 s was requriedfor 95 % of the liquid to be in contact with the porous bed, although this timewas not verified experimentally.

The purpose of this paper was to analyse how the ISLE method and the TV-show theMythbusters correspond to one another, to the Swedish upper secondary physics curriculum andPopper’s philosophy about research methods.The study aims to respond to the following research questions: 1. How do the structures of the Mythbusters and ISLE relate to one another? 2. What are the possibilities and potential benefits and drawbacks of implementingISLE with a Mythbusters approach in physics education? 3. To what extent do the Mythbusters and ISLE approaches present natural sciencepractices that are in line with Popper’s view of the nature of science? The paper shows that the structures of the Mythbusters and ISLE approaches to teaching andproblem solving relate via their focus upon scientific methods. Both give, to some degree, thepeople that interact with them confidence and tools to be able to analyse events they observe.The analysis found some isolated parts of correspondence between the Mythbusters andPopper’s view of nature and science. ISLE, however, is pervaded by Popper’s ideas of scientificmethods, where the main assumption is that you cannot prove anything, you may only try tofalsify it and thereby give the hypothesis a higher corroboration.Even though the creator of ISLE motivates the reasoning of choosing the falsification andcorroboration as main ingredients in a way that differs from Popper’s arguments, its essence ofthe concepts is still there.If an instructor were to include the Mythbusters, with for example using myths that the showtreated as an hypothesis, when implementing ISLE in a physics education course, the coursewould correspond quite well will Karl Popper’s idea of falsification and corroboration. It is alsogiven an implication that the students perform better when the TV-show is used as tool to learnabout scientific methods. The inclusion of Mythbusters as a resource for learning can serve as abridge between popular culture, everyday phenomena and school physics, which can potentiallyhave a positive impact on student motivation.

Science fiction och populärmedia är en stor del av vardagen i dagens samhälle. Elever konsumerar den typen av media på egen tid och söker sig till den för underhållning utanför skolans väggar, möjligen utan att reflektera över vad det är som konsumeras. Den här studien fokuserar på science fiction och hur de välproducerade medierna tas emot och reflekteras kring av konsumenterna, som i det här fallet är elever. Finns det möjlighet för lärare inom fysik eller någon annan naturvetenskap att utnyttja det intresse och den pseudovetenskap, som dessa medier kan förmedla, i skolan? Elever har en bild av vad fysik är i skolans värld efter hur fysikundervisningen är upplagd och syftet för arbetet är att undersöka möjliga sätt som de olika världarna kan mötas. Det riktar sig mot att utvärdera en undersökning gjord i en elevgrupp bestående av 6 fysikstuderande elever på gymnasiet. Kärnan i undersökningen är att se vilka typer av diskussioner som uppstår efter visning av ett eller flera filmklipp från populära spelfilmer, innehållande fysiska moment. De fysiska momenten är sekvenser som kan förklaras med den fysik vi har idag eller så kan det vara orimliga sekvenser som inte går att förklara. Eftersom den här typen av media ofta bygger på att skapa känslor hos konsumenten så förekommer det att verklighetsförankringen ofta försvinner. Det teoretiska ramverk som undersökningen håller sig till utgår i konceptet ägandeskap av lärande och syftar till hur elever utvärderar sina egna idéer och tar ansvar för att följa upp tidigare funderingar eller frågor som de själva uttryckt. På så vis kan eleverna själva förhoppningsvis se värdet av kritiskt tänkande och även att eleverna kan minnas vad de lärt sig över en längre tid. / Science fiction or rather popular media is a major part of everyday life in today's society. Students consume this media in their spare time and watch it for entertainment, possibly without even reflecting over the consumed content. This paper will focus on science fiction and how the well-produced media is received and reflected upon by the consumers, in this case upper-secondary physics students. Is there an opportunity for physics teachers or other natural sciences teachers to make good use of the interest and the pseudo science, that these media can convey, at school? Pupils have an idea of what physics is in school considering how physics education is laid out and the purpose of this work is to explore possible ways that these different worlds can meet. The work is aimed at evaluating a one hour session done with a student group consisting of 6 physics students in high school. The essence of the survey is to see what types of discussions occur after viewing one or more movie clips containing different physical phenomena. The physical events are shown in movieclips and can be explained by the physics we have today or there may be unrealistic events that cannot be explained. This kind of popular media is often based on creating emotional connections with the consumer which can take away the connection to reality and the real world physics. The theoretical framework that the study was based on is the concept of ownership of learning, this aims to consider how students evaluate their own ideas and take responsibility for following up on previous ideas or questions that they themselves expressed. That way the students hopefully find value in critical thinking and the retention of knowledge might increase.

Mitt arbete gjordes för att ta reda på vilken typ av laboration som är vanligast i fysikundervisningen på gymnasiet, vilka mål lärare har med olika typer av laborationer, samt vilka av målen elever själva tycker att de har uppnått i samband med laboration. Uppdelning och indelandet av laborationerna är grundat på tillvägagångssättet i dess utförande. Denna undersökning behandlar framförallt deduktiv respektive induktiv laboration. Undersökningen genomfördes på en gymnasieskola och de berörda eleverna går på ett naturvetenskapligt program. De fick svara på två enkäter, en vid deduktiv laboration och en vid induktiv laboration, medan lärarna intervjuades. Resultatet visar att den vanligaste laborationen som används i fysikundervisningen är den deduktiva laborationen. Lärarna vill uppnå fyra huvudmål: länka teori till praktik, utveckla praktiska och experimentella färdigheter, förmedla vetenskapliga metoder, öka motivationen. Detta resultat stämmer väl överens med tidigare forskningrapporter och böcker från min litteraturgenomgång. Resultatet av enkäterna visar att eleverna själva tycker att de uppnår lärarens viktigaste mål med laborationerna, men deras egen bedömning stämmer inte överens med vad de verkligen kan. Detta bekräftar också tidigare forskningsresultat. Eleverna har svårt att uppnå laborationernas mål.

We formulate a process of quantization of classical mechanics, from a symplecticperspective. The Dirac quantization axioms are stated, and a satisfactory prequantizationmap is constructed using a complex line bundle. Using polarization, it isdetermined which prequantum states and observables can be fully quantized. Themathematical concepts of symplectic geometry, fibre bundles, and distributions are exposedto the degree to which they occur in the quantization process. Quantizationsof a cotangent bundle and a sphere are described, using real and K¨ahler polarizations,respectively.

In composite materials, transverse shear modulus is a critical moduli parameter for designing complex composite structures. For dependable mathematical modeling of mechanical behavior of composite materials, an accurate estimate of the moduli parameters is critically important as opposed to estimates of strength parameters where underestimation may lead to a non-optimal design but still would give one a safe one. Although there are mechanical and empirical models available to find transverse shear modulus, they are based on many assumptions. In this work, the model is based on a three-dimensional elastic finite element analysis with multiple cells. To find the shear modulus, appropriate boundary conditions are applied to a three-dimensional representative volume element (RVE). To improve the accuracy of the model, multiple cells of the RVE are used and the value of the transverse shear modulus is calculated by an extrapolation technique that represents a large number of cells. Comparing the available analytical and empirical models to the finite element model from this work shows that for polymeric matrix composites, the estimate of the transverse shear modulus by Halpin-Tsai model had high credibility for lower fiber volume fractions; the Mori-Tanaka model was most accurate for the mid-range fiber volume fractions; and the Elasticity Approach model was most accurate for high fiber volume fractions. Since real-life composites have voids, this study investigated the effect of void fraction on the transverse shear modulus through design of experiment (DOE) statistical analysis. Fiber volume fraction and fiber-to-matrix Young’s moduli ratio were the other influencing parameters used. The results indicate that the fiber volume fraction is the most dominating of the three variables, making up to 96% contribution to the transverse shear modulus. The void content and fiber-to-matrix Young’s moduli ratio have negligible effects. To find how voids themselves influence the shear modulus, the transverse shear modulus was normalized with the corresponding shear modulus with a perfect composite with no voids. As expected, the void content has the largest contribution to the normalized shear modulus of 80%. The fiber volume fraction contributed 12%, and the fiber-to-matrix Young’s moduli ratio contribution was again low. Based on the results of this work, the influences and sensitivities of void content have helped in the development of accurate models for transverse shear modulus, and let us confidently study the influence of fiber-to-matrix Young’s moduli ratio, fiber volume fraction and void content on its value.