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Syftet med denna litteraturstudie är att kartlägga vilka metoder som kan användas för att intressera elever för fysikämnet i grundskolan. Studien är avgränsad till fysik och fysikundervisning på grundskolan i både svensk och internationell litteratur. Utifrån syftet kunde en frågeställning formuleras:  Vilka metoder kan användas för att öka elevernas intresse och engagemang på fysik på grundskolan? Litteraturstudien bygger på systematiska sökningar som har gjorts i databaserna Google Scholar och ERIC. Resultatet visar att det finns flera faktorer som påverkar elevernas förståelser av fysik och några av dem är t.ex. elevernas hemförhållande och bakgrund, arbetsmetoder som används i undervisningen och vilka matematiska kunskapersnivåer som eleverna har. Resultaten i litteraturstudien visar även att elever behöver stöd i undervisningen med hjälp av olika metoder samt att föräldrarnas roll har en stor betydelse för elevers lärande i skolan. Resultatet ger också en stark koppling mellan elevernas upplevelser av svårighet och elevernas intresse för fysikämnet. Ju större intresse för ämnet, desto mindre svårt uppfattas det av eleverna.

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This thesis presents theoretical research on MAX phases (M=transition metal, A=A-group element, X=carbon and/or nitrogen), with focus on predictions of phase stability as well as of physical properties. The first part is an investigation of the phase stability of the MAX phases Ti2AlC, Ti3AlC2, and Ti4AlC3 at elevated temperatures, where the former two phases have been obtained experimentally. Phase stability calculations of MAX phases usually do not take temperature dependent effects such as electronic excitations and lattice vibrations into consideration due to significantly increased computational cost. The results have nevertheless so far been quite accurate, with good agreement between theory and experiments. Still, the question whether the inclusion of temperature into the calculations could significantly alter the results as compared to previous 0 K calculations needs to be investigated, since this has bearing on the reliability of future predictions of the stability of not yet known MAX phases. However, it is shown that for Tin+1AlCn, the different temperature dependent effects largely cancel each other. The results therefore suggest that to go beyond 0 K calculations for phase stability predictions of MAX phases is motivated only for borderline cases. The second part investigates the Mn2GaC MAX phase, which was recently predicted from theoretical phase stability calculations and subsequently synthesized. As a new member of the MAX phase family as well as being one of the first known MAX phases to exhibit magnetism, it is of interest to explore its physical properties. Here, we have used firstprinciples calculations to determine the electronic, vibrational and elastic properties. Analysis of the electronic band structure indicates anisotropy in transport properties, while the electronic and phonon density of states shows that the relative orientation of the Mn magnetic moments over the Ga layers affects the distribution of the electronic and vibrational states for both Mn and Ga. The Voigt bulk, Voigt shear, and Young's modulus is also investigated, together with the Poisson's ratio, the elastic anisotropy, and the  machinability via two machinability indices. In relation to experimental results of the moduli of other M2AC phases, the Voigt bulk and shear moduli are concluded to be fairly low, 157 and 93 GPa, respectively, while the magnitude of the Young's modulus at 233 GPa is intermediate. The Poisson's ratio, which is 0.25, on the other hand, is comparatively high. The phase is shown to be elastically quite isotropic, and, just as other M2GaC phases, also machinable. As all here investigated properties are affected by the choice of magnetic spin configuration, the results show the importance of identifying the correct magnetic ground state in future theoretical work on magnetic MAX phases. / <p>The series name of this thesis <em>Linköping Studies in Science and Technology Licentiate Thesis</em> is incorrect. The correct name is <em>Linköping Studies in Science and Technology Thesis</em>.</p>

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Radar sensors has been known for their usage in military applications but during the last decade commercial radar sensors have been implemented for usage in for example advanced driver-assistance system. One common implementation for advanced driver-assistance system is the adaptive cruise control technology implemented in vehicles to help it adapt the velocity based on the distance to a detected vehicle in front. The development of the commercial radar sensors have made radar sensors cheaper and more accessible. The goal of this thesis is to investigate the civil market to see if there are any radar sensors available that could be of interest to use for applications in proximity fuzes. A proximity fuze can be used in projectiles to initiates its explosion when the projectile is positioned an optimal distance from the target where the distance can be estimated by using a radar system. Investigation of the civil market was made by performing a literature study by looking into articles about civil use applications for frequency modulated continuous wave radars and pulsed Doppler radars operating with a frequency in the GHz-area. In the literature study, five interesting frequencies were identified for the frequency modulated continuous wave radar: 24 GHz, 35 GHz, 77 GHz, 94 GHz and 122 GHz. For each article different properties regarding the sensors’ performance was investigated. Example of a few of the properties investigated was the sensor’s limitation of maximum range, angle and velocity. Based on the literature study’s result a 77 GHz radar sensor included in an evaluation kit was ordered and used to perform a proof-of-concept where the radar sensor’s performance was evaluated. The proof-of-concept was made by analyzing if the radar sensor could detect a drone at distances between 5 m and 20 m at rest or moving with a velocity of approximately 3 m/s. Two scenarios were tested for the drone and the sensor. In the first scenario, possible background clutter was eliminated while the second scenario included some background clutter. The sensor was able to detect the drone at all positions when moving or at rest, but for the second scenario there were some difficulties to get a clear detection of the target at 10 m and 20 m distance. Distance and angle measurements were performed on a metal plate having a larger radar cross section than the drone. The evaluation kit was able to detect the object at distances between 5 m and 20 m and when the object was placed 10 m away from the sensor in both x- and y-direction i.e. 45 ° from the sensor. From these results it could be concluded that radar sensors used for automotive applications has potential to be used for proximity fuze applications but further tests have to be made before a definitive conclusion can be made. The sensor has to be tested for higher velocities than 500 m/s and for larger distances to be able to determine if this type of sensor could be applied in proximity fuzes. / Radarsensorer har länge använts inom militära applikationer men har på senare tid introducerats på den civila marknaden i form av exempelvis adaptiva farthållare i fordon. Radarsensorn hjälper fordonet att detektera avståndet till fordonet framför samt medför att den kan korrigera hastigheten för att hålla ett säkert avstånd och minska risken för olyckor. Utvecklingen inom den civila marknaden har lett till att radarsensorer idag är både billiga och lättillgängliga. Syftet med detta examensarbete har varit att undersöka den civila marknaden för att se om det finns någon tillgänglig radarsensor som skulle kunna användas för applikationer i zonrör. Marknaden genomsöktes genom att genomföra en litteraturstudie där artiklar innehållande information om frekvensmodulerade kontinuerlig våg radar och pulsad Doppler radar som opererar med en frekvens i GHz-området studerades. Faktorer och egenskaper som tillgänglighet, räckvidd och spridningsvinkel var några av de egenskaper som analyserades. I denna studie hittades fem intressanta frekvenser för frekvensmodulerad kontinuerlig våg radar som används inom olika applikationer på den civila marknaden, 24 GHz, 35 GHz, 77 GHz, 94 GHz och 122 GHz. Baserat på litteraturstudiens resultat beslutades att en 77 GHz radarsensor skulle utvärderas genom fysiska tester för att utvärdera radarsensorns prestanda. Först undersöktes om radarsensorn kunde detektera en drönare på avstånd upp till 20 m i en miljö med eller utan störningar i omgivningen. Tester genomfördes för drönaren när den befann sig i vila eller i rörelse med en hastighet på ungefär 3 m/s. Radarsensorn lyckades detektera testobjektet under samtliga avstånd, hastigheter och miljöer men hade vissa svårigheter att få en tydlig detektering av objektet i miljön innehållande bakgrundsstörningar. Tester genomfördes också på en metallplatta med större radarmålarea än drönaren. Radarsensorn lyckades detektera testobjektet på ett avstånd upp till 20 m och när objektet befann sig 10 m från sensorn i både x- och y-riktning d.v.s. 45 ° från utvärderingsmodulen. Utifrån dessa resultat framkom det att radarsensorer utformade för autonoma applikationer har potential att användas i zonrörs-tillämpningar men att vidare tester för längre avstånd och högre hastigheter måste genomföras innan en slutgiltig slutsats kan dras.

This paper which is a thesis for the title teknologie licentiat is a summary text of several works performed by the author regarding spectroscopic measurements on spent nuclear fuel. Methods for determining the decay heat of spent nuclear fuel by means of gammaray spectroscopy and for verifying the integrity of nuclear fuel by means of tomography is presented. A summary of work performed regarding gammaray detector technology for studies of fission gas release is presented.

Defects such as mold and bacterial stains can appear on cheese. Manually detecting defects is a time-consuming, cost-ineffective, and ergonomically unsatisfactory process for a dairy because the quality technicians must inspect each cheese before packaging. Instead, dairies would prefer an automatic detection system, but it is unclear whether reliable options are available. One potential approach is hyperspectral image analysis, which can interpret and classify chemical information from a sample. We collected hyperspectral images from a dairy using a short-wave infrared (SWIR) camera and compared three prediction models: a PLS-discriminant analysis with the software Breeze from the analysis company Prediktera and two classifiers based on a convolutional neural network and a support vector machine, both coded in Python. We found mold and lactobacilli stains using all methods, but dirt was more challenging to detect. Also, the methods had issues with false positives of lactobacilli stains. To improve accuracy, we recommend collecting more data, especially samples with lactobacilli stains and dirt, and using more non-defect cheese for validation. To find smaller defects, we propose that future work should test a visible and near-infrared (VNIR) camera with higher resolution. Though PLS-discriminant analysis did not achieve the highest accuracy, it was not far off and had the most time-effective predictions. Since Breeze already integrates PLS-discriminant analysis, it should remain in focus, but for higher accuracy Prediktera should continue to explore other methods such as neural networks.

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