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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Quantum Computational Speedup For The Minesweeper Problem

Terner, Olof, Urpi Hedbjörk, Villhelm January 2017 (has links)
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.
122

Compaction of Lattice Data : Improved Efficiency in Nuclear Core Calculation

Lundgren, Hanna January 2017 (has links)
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.
123

Development of a CFD Model for a Rotating Bed Reactor in Large Volumes

Lundberg, Karl January 2017 (has links)
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.
124

Introducing ISLE with an Inspiration from the Mythbusters

Ljunggren, Pär January 2018 (has links)
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.
125

Fysikundervisningens science fiction / Science fiction in physics education

Sjörs, Simon January 2017 (has links)
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.
126

Laborationen i fysikundervisningen : lärares mål med olika typer av laborationer och vilka av dessa mål eleverna uppnår

Luu, Thi Le Hang January 2016 (has links)
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.
127

Geometric Quantization

Hedlund, William January 2017 (has links)
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.
128

Fenomenet fysik som innehåll i förskolans verksamhet : Förskollärarnas uppfattning / The Phenomenon of Physics as a Part of the Preschool : The Preschool Teachers Perception

Eriksson, Nathalie January 2017 (has links)
The purpose of this study was to ascertain how preschool teachers think the subject of physics is shown in the preschool environment. A comparison was also conducted to see if there was any difference between the preschool teachers view of working with physics depending on when they were educated.   The study was conducted in the form of qualitative semi-structured interviews with active preschool teachers. The interviews were conducted in a calm environment and there was no disturbances. The interviews were used as a foundation to see if the preschool teachers thought they had sufficient knowledge in physics to be able to complete their work. A comparison was made between two newly graduated preschool teachers and two preschool teachers educated in the 1990s.   The results show that the preschool teachers think physics is an interesting subject, but they don’t work with it sufficiently. They believe the reason for that this is insufficient material, lack of time, conflicting colleagues and ignorance.
129

Modelling the Dynamics and Forcesof Wave Energy Converters using WEC-Sim

Johansson, David January 2020 (has links)
The waves traveling on the surface of the world’s oceans carry atremendous amount of energy. The ability to convert this energy forhuman use has the potential to help solves the worlds energy problem. Adirect-drive linear generator point absorber is a wave energy converter(WEC) that aims to reduce the complexity of the overall system andshelter the most vulnerable parts of the system by placing them on theseabed. This concept builds around the buoy moving up and down indifferent sea-states which leads to a correlating vertical movement of thestroke in the generator resulting in the conversion of mechanical energyto power. This report aims to explore the possibility to use the open codeWEC-Sim to model the Uppsala University direct-drive linear generatorWEC in extreme sea states and to identify the resulting extreme loads. Theconstructed WEC-Sim model constrained the buoys motion in heave andsurge and limited its range of motion by modeling the generators upperend-stop spring. Simulations were run for different sea-states and theresulting forces on the system were analyzed. The peak line force for thedifferent sea states was calculated and compared to previous studies. Theresults validated the model as they showed a good correlation for mostsea-states. It was only for larger significant wave heights that there was adivergence compared to the results in previous studies.
130

Raman spectroscopy in neurosurgery

Bergqvist, Saga January 2020 (has links)
Brain tumors or brain cancer is a disease than affects people of all ages. The median age of a person living with a brain tumor is 60 years, it is however a disease that affects children and young adults in high grade. Brain cancer is the second most common type of cancer among children and is also the most common cause of cancer related death among this group. To ensure that the damages on the brain is as small as possible, it is important that a tumor can be diagnosed and removed as early as possible. Previous methods of diagnosis is based on biopsy where a part of the tumor is removed and examinated by a pathologist. This is a time consuming process that also is biased by the human factor, there is therefore a need for a method that can be used \textit{in situ} with an unbiased result. One method that have shown great promise is photensitation with 5-Aminolevoluic acid (5-ALA). However, this method have shown to only work properly on tumors of high malignancy in adults. As a comlpiment to photosentisation, Raman spectroscopy have shown good promise in previous studies.  This study was conducted to investigate the use of Raman spectroscopy as a tool for \textit{in situ} brain tumor diagnostics. The use of Raman spectroscopy was tested by comparing two previously performed studies, where they looked at a number of Raman bands from biological markers that are known to change in cancerous tissue as well as the intensity ratio between some Raman bands.  A measurement system for Raman spectroscopy was designed and built at Luleå University of Technology where the system were evaluated on tissue samples from conventional meat i.e. pork and beef to ensure that is was possible to achieve spectroscopic information of protein and lipid content in tissue. The measurement system was then transported to Linköpings University where the measurements on six brain tissue samples where performed. The samples came from five different tumors of which one tumor was thought to come from a high malignant tumor based on preliminary histopathological analysis and four from low malignant or benign tumors. Two samples where obtained from the high malignant tumor that was photosentisized with 5-Aminolevoluic acid and one of the samples where illuminated with blue light prior to the Raman spectroscopic measurements.  The spectroscopic data was pre-processed before analysis using conventional methods. The analysed spectra from the brain tissue samples showed presence of the Raman bands associated with brain tissue. It was also possible to see Raman bands associated with 5-ALA in the samples that had been photosentisized, however when the tissue had been illuminated with blue light it was also possible to see distinct Raman bands associated with brain tissue. One tissue sample also showed presence of reduced Neuroglobin (NGB). The composition of NGB is also known to change in tumorous tissue and could therefore be used in future work as a biological marker for brain tumors. When comparing the results obtained in this study with the two previously performed, one of the studies showed that two samples were from a tumor of high malignancy and the other from low malignant or benign tumors. This result was in accordance with the preliminary histopathological assessment of the brain tissue samples. When comparing the results to the other study, the results where contradictory and indicated that all tissue samples where from low malignant or benign tumors.  The conclusion of this work is that Raman spectroscopy is possible to use as a tool for brain tumor diagnostics. It would be desirable to use this method in combination with 5-ALA staining since the Raman bands from brain tissue could be resolved when the tissue had been illuminated with blue light. / Hjärntumörer kan drabba människor i alla åldrar, medelåldern för människor som lever med en hjärntumör är 60 år, men det är ett tillstånd som även drabbar barn och unga i stor utsträckning. Hjärntumörer är den näst vanligaste cancerformen hos barn och är även den främsta orsaken till cancerrelaterad död i den åldergruppen. För att minimera skadorna på hjärnan är det viktigt att en tumör kan lokaliseras och tas bort så tidigt som möjligt. De metoder som används idag bygger framför allt på biopsi, där en del av tumören tas bort och undersöks av en histopatalog. Det är en process som tar lång tid och även påverkas av den mänskliga faktorn, det finns därmed ett behov av en metod som kan avändas \textit{in situ} som ger ett resultat som inte påverkas av den mänskliga faktorn. En metod som har visat lovande resultat är fotosensibilisering med 5-Aminolevulinsyra (5-ALA). Desvärre har den metoden bara visat sig fungera bra för högmaligna tumörer hos vuxna. Som ett komplement till fotosensibilisering har Ramanspektroskopi visat lovande resultat i tidigare genomförda studier.  Det här arbetet genomfördes för att undersöka användningen av Ramanspektroskopi som ett verktyg för diagnostisering av hjärntumörer. Som grund användes två tidigare genomförda studier där de undersökte Ramanband från biologiska markörer i hjärnvävnad som ändras i cancerogen vävnad. De undersökte även hur den biokemiska sammansättningen av hjärnvävnaden ändrades genom att jämföra intensiteten av olika Ramanband.  Ett mätsystem för Ramanspektroskopi designades och byggdes upp på Luleå Tekniska Universitet där det även testades på vävnad från kött (fläsk och biff). Därefter transporterades mätsystemet till Linköpings Universitet för att genomföra mätningar på sex olika vävnadsprov från fem hjärntumörer av olika malignitet. Baserat på en preliminär histopatalogisk bedömning var en av tumörerna högmalignt och de fyra andra tumörerna var antingen lågmalignta eller benigna. Två av proverna som undersöktes kom från den högmalignta tumören som även var fotosensibilierad med 5-Aminolevulinsyra, varav ett av proverna var belyst med blått ljus innan de Ramanspektroskopiska mätningarna genomfördes.  Innan resultatet från Ramanspektroskopiska mätningarna analyserades behandlades datan med konventionella metoder i MatLab. I de resulterade spektrumen gick det att se tydliga Ramanband associerade med hjärnvävnad. Det gick även att se Ramanband associerade med 5-ALA i de två prover som var fotosensibiliserade och i det provet som var belyst med blått ljus innan de spektroskopiska mätningarna gjordes gick det även att se tydliga Ramanband associerade med hjärnvävnad. När resultatet analyserades gick det även att se spektra associerat med reducerat Neuroglobin (NGB) i ett av proverna. Sammansättningen av NGB är också någonting som ändras i cancerogen vävnad och skulle därför också kunna användas som en bilogisk markör för hjärntumörer i framtida studier.  När resultaten från den här studien jämfördes med de tidigare studierna indikerade den ena studien att två av vävnadsproverna kom från en högmalignt tumör och att de resterande fyra från lågmaligna eller benigna tumörer, vilket stämmer överens med den preliminära diagnosticeringen av tumörerna. När resultatet istället jämfördes med den andra studien stämde inte resultatet lika bra med den preliminära diagnosticeringen av tumörerna. Metoden presenterad av Zhou m.fl. indikerade att alla tumörer kom från lågmaligna eller benigna tumörer.  Slutsaten av det här arbetet är att Ramanspektroskopi skulle kunna användas som en metod för diagnosticering av hjärntumörer. Metoden skulle även fungera bra som ett komplement till fotosensibilisering med 5-ALA eftersom att det var möjligt att se Ramanband associerade med hjärnvävnad när vävnaden hade belysts med blått ljus.

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