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  • 51.
    Berggren, Mats
    et al.
    Tiundaskolan, Uppsala.
    Isleborn, Helena
    Tiundaskolan, Uppsala.
    Haglund, Jesper
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013). SMEER; Institutionen för pedagogik, didaktik och utbildningsstudier, Uppsala universitet.
    Kärnkraftsdebatt ger möjlighet till kritiskt tänkande i högstadiefysiken2019Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    I skolans styrdokument betonas vikten av att elever ges möjlighet att utveckla sitt kritiska tänkande. Detta är inte minst angeläget i dessa tider av tillgång till sociala medier och spridande av så kallade alternativa fakta. Trots sin positiva klang finns det dock ingen etablerad konsensus kring vad kritiskt tänkande egentligen är. Inom ramen för ett skolutvecklingsprojekt i samverkan mellan Uppsala universitet och Tiundaskolan, en 4-9-skola i Uppsala, utforskar vi hur kritiskt tänkande kan uttryckas i undervisningspraktiken i ämnena svenska, historia, matematik och fysik. Som exempel har vi i fysikämnet designat, genomfört och analyserat en undervisningssekvens utifrån kärnkraft som tema, där elever i årskurs 9 gavs möjlighet att anamma olika åsikter och argument i frågan genom rollspel. Eleverna genomförde en debatt, där de representerade olika parter: boende nära Forsmark, miljöorganisationen Grön Fred, och företag som utvecklar kärnkraft, respektive vindkraft. Före och efter debatten skrev eleverna individuella texter där de argumenterade för sin personliga åsikt i frågan: Ska kärnkraften bevaras som den är, läggas ner, eller utvecklas? Vi fann att de genom debatten fick goda möjligheter att utveckla och visa kunskaper motsvarande flera kunskapskrav i kursplanen i fysik som annars sällan berörs i fysikklassrummet, såsom, för betyg A: ”Eleven kan samtala om och diskutera frågor som rör energi, teknik, miljö och samhälle och skiljer då fakta från värderingar och formulerar ställningstaganden med välutvecklade motiveringar samt beskriver några tänkbara konsekvenser.” Som exempel på naturvetenskapligt förankrade argument utnyttjade eleverna genererad energi per utsläppt mängd koldioxid som ett mått vid jämförelser mellan kärnkraft och andra energikällor. I de individuella texterna höll de flesta eleverna fast vid sina åsikter från innan de arbetade med temat även efteråt, men nu med fler och mer nyanserade argument.

  • 52.
    Bergh, Gustav
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Förslitning av fräsverktyg2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 53.
    Bergstrand, Fredrik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Konstruktion av en mobil nödduschanläggning: En produktutveckling åt Gia Premix AB2018Självständigt arbete på grundnivå (högskoleexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Projektet har utförts som ett examensarbete på uppdrag av Gia Premix AB som avslutning på programmet högskoleingenjör i maskinteknik vid Karlstads universitet under våren 2018.

     

    Examensarbetet behandlar framtagning och konstruktion av en mobil nödduschanläggning för breddning av Gia Premix sortiment. Projektet grundar sig i att företaget under senare tid sett behov av att ha en mobil nödduschanläggning i sitt sortiment. Då man inte har någon konstruktion i dagsläget valdes det att lägga detta som ett examensarbete. Arbetet behandlar alla ingående delar i projektet från bakgrund via metodval till konstruktion och slutsats.

     

    I konstruktionsdelen av produkten har hållfasthetsberäkningar genomförts för att kunna dimensionera material i konstruktionen, dessa har utförts både manuellt men även med hjälp av FEM-analys i datormiljö där geometrier var komplicerade. Framställning av komponenter har gjorts med hjälp av CAD och utifrån dessa har ett komplett ritningsunderlag tagits fram.

     

    Alla mål som var uppsatta för projektet är uppfyllda. Ett 40-tal ritningar har tagits fram för att ligga som grund för en framtida tillverkning av prototyp. Isolering av rör samt anslutning av duschenheter till pumpsystem avgränsades från projektet och kan återfinnas som förslag till lösningar under avsnittet förslag på vidare arbete. Målet kring att lämna förslag på lösningar till delarna som innefattas av avgränsningarna har uppfyllts med gott resultat.

  • 54.
    Bergstrom, Jens
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Burman, Christer
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Svensson, Jonas
    Atlas Copco Rock Drills AB, Klerkgatan 21, SE-70225 Orebro, Sweden..
    Jansson, Andreas
    Atlas Copco Rock Drills AB, Klerkgatan 21, SE-70225 Orebro, Sweden..
    Ivansson, Charlotta
    Atlas Copco Rock Drills AB, Klerkgatan 21, SE-70225 Orebro, Sweden..
    Zhou, Jing
    Atlas Copco Rock Drills AB, Klerkgatan 21, SE-70225 Orebro, Sweden..
    Valizadeh, Sima
    Atlas Copco Rock Drills AB, Klerkgatan 21, SE-70225 Orebro, Sweden..
    Very High Cycle Fatigue of Two Ductile Iron Grades2016Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 87, nr 5, s. 614-621Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two ductile iron grades, EN-GJS-600-3 a ferritic-pearlitic grade, and EN-GJS-600-10 a silicon strengthened ferritic nodular iron grade, are studied in the very high cycle fatigue range using a 20kHz ultrasonic test equipment. Fatigue strengths and SN-curves are achieved, and fracture surfaces and microstructures are investigated. The ferritic grade with higher ductility displays a lower fatigue strength at 10(8) load cycles than the ferritic-pearlitic grade, 142 and 167MPa, respectively. Examination of fracture surfaces shows that fatigue failures are controlled by micropores in both of the ductile iron grades, while the graphite nodule distributions do not seem to influence the difference in fatigue strengths. Prediction of the fatigue strengths, using a model for ductile iron proposed by Endo and Yanase, indicates a large potential for improvement in particular for the ferritic grade.

  • 55.
    Bergström, Jens
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Kazymyrovych, Vitaliy
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Burman, Christer
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Ekengren, Jens
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Test specimen geometry, stress calculation and mean stress in 20kHz testing in the very long fatigue life region2011Ingår i: VHCF5 5thInternational Conference on Very High Cycle Fatigue / [ed] Christina Berger, Hans-Jurgen Christ, Berlin: Deutcher Verband fur Materialforschung und prufung , 2011, s. 315-320Konferensbidrag (Refereegranskat)
  • 56.
    Bertoni, M. I.
    et al.
    Arizona State Univ, USA.
    Sarau, G.
    Germany.
    Fenning, D. P.
    Rinio, Markus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik. Frauenhofer ISE, Germany.
    Rose, V.
    USA.
    Maser, J.
    USA.
    Buonassisi, T.
    USA.
    Nano-XRF and micro-Raman Studies of Metal Impurity Decoration around Dislocations in Multicrystalline Silicon2012Ingår i: 2012 38TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC), New York, USA: IEEE, 2012, s. 1613-1616Konferensbidrag (Refereegranskat)
    Abstract [en]

    We push the resolution limits of synchrotron-based nano-X-ray fluorescence mapping below 100 nm to investigate the fundamental differences between benign and deleterious dislocations in multicystalline silicon solar cells. We observe that after processing recombination-active dislocations contain a high degree of nanoscale iron and copper decoration, while recombination-inactive dislocations appear clean. To study the origins of the distinct metal decorations around different dislocations we analyze as-grown samples as well as specimens at different stages of processing. We complement our X-ray studies with micro-Raman mapping to understand the relationship between metallic decoration and stress fields around dislocations.

  • 57.
    Biel, Anders
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Stigh, U.
    Högskolan Skövde.
    Comparison of J-integral methods to experimentally determine cohesive laws in shear for adhesives2019Ingår i: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 94, s. 64-75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-quality simulation methods demand accurate material models. In simulations an adhesive can be represented by a cohesive layer. A cohesive layer model utilizes a cohesive law to represent the homogenized mechanical behaviour of a layer with a thickness. In the current paper we use three experimental methods to measure the cohesive law in shear using the ENF-specimen; one of the methods is novel and is also useful for evaluation of experiments with the ELS-specimen. Two sets of experiments are performed, one with elastic substrates and one with plastically deforming substrates. Each experiment is evaluated using all three methods. The evaluation shows that all methods provide reasonable data; the results are similar if the substrates are elastic. With smaller specimens, the substrates deform plastically and one of the methods is identified as the most accurate.

  • 58.
    Bjornsson, Jonas
    et al.
    Univ Cambridge, Dept Appl Math & Theoret Phys, Cambridge CB3 0WA, England..
    Hwang, Stephen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik. Karlstad Univ, Dept Phys, SE-65188 Karlstad, Sweden..
    Gauged non-compact WZNW models, revisited2010Ingår i: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 832, nr 1-2, s. 52-88Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of the present paper is to investigate the necessary conditions for unitarity of the spectrum of non-compact gauged WZNW models to some depth. In particular, we would like to investigate the necessity of integer weights and level. We will learn that the problem is very complex and we have not found any simple and general way to formulate the necessary conditions. Instead one must resort to studying the problem almost case by case. The only nearly complete conditions that we will find, is for the case g = su(n, 1). Furthermore, the horizontal part of the case g = su(p, g) is nearly completed as well. In other cases, we will find conditions associated with certain subalgebras and nodes in the Dynkin diagram close to the one corresponding to the non-compact root. In these examples we can give conditions for the horizontal part of the algebra. As a by-product of our investigation we will prove some nice formulae of character identities and explicit branching functions for these representations. (C) 2010 Elsevier B.V. All rights reserved.

  • 59.
    Blazinic, Vanja
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Probing the effects of photodegradation of acceptor materials in polymer solar cells: bulk, surface, and molecular level2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Polymer solar cells (PSC) have reached record power conversion efficiencies of over 15%. The operational lifetime of PSCs, however, has to increase for their use in large area outdoor applications. In this work, a set of spectroscopic techniques (UV-vis, FTIR, NEXAFS, XPS) was used to study the impact of exposure to light and air (photo-oxidation) on the photoactive layer and its components. We focused on the electron acceptor components: the fullerene derivatives, PC60BM and PC70BM, and the polymer N2200. A comparative study of photo-oxidized PC60BM and PC70BM thin films by UV-vis and FTIR spectroscopy has shown that both materials undergo similar photochemical transformation, with the process being faster in PC60BM, due to the greater curvature of the C60 cage. Comparing experimental FTIR, XPS and NEXAFS spectra of the photo-oxidized PC60BM thin films with the calculated spectra for a large variety of photo-oxidation products, it was found that dicarbonyl and anhydride groups attach to the C60 cage during photo-oxidation. The study of photo-oxidized TQ1:PC70BM blend films by spectroscopic and J-V measurements shows that deterioration of the charge transport in PC70BM is the major contributor to the device performance degradation. Kelvin Probe measurements demonstrated that the charge transport deterioration was due to upward band bending and gap states being formed on the surface of photo-oxidized PC70BM. The TQ1:PC70BM blends films were further studied by AFM-IR in order to determine the lateral distribution of pristine components, as well as the photo-oxidation products. It was found that anhydride oxidation products of PC70BM are equally distributed over the blend film surface. The PC70BM is replaced with the polymer N2200 in the blend with TQ1. The photostability in air of the blend and its neat components was studied by UV-vis and FTIR spectroscopy. The spectra show that thermal annealing improves the photostability in air of both components.

  • 60.
    Blazinic, Vanja
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Ericsson, Leif
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Levine, Igal
    Hansson, Rickard
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Opitz, Andreas
    Moons, Ellen
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Impact of intentional photo-oxidation of a donor polymer and PC70BM on solar cell performance2019Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A short lifetime is the main factor hindering the wider implementation of low-cost organic photovoltaics in large-area and outdoor applications. Ingress of oxygen and water vapour through non-ideal encapsulation layers is a known cause of degradation for polymer/fullerene based solar cells. To better understand the origin of this performance degradation, we study the effect of intentional exposure of the photo-active layer to simulated sunlight (AM1.5) in air both on the solar cell performance and on the molecular semiconductor materials. Cathode-free thin films of a blend of the electron donor polymer poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1) and the electron acceptor fullerene derivative [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) were exposed to simulated sunlight in air. Fourier-transform infrared spectra demonstrate the formation of carbonyl photo-oxidation products in the blend films, as well as in the pristine polymer and fullerene films. Solar cells prepared with photo-oxidized active layers show increasingly degraded electrical performance (lower short circuit current, open circuit voltage and fill factor) with increasing exposure time. The increased diode ideality factor indicates that trap-assisted recombination hinders device operation after exposure. The external quantum efficiency decreases drastically with increasing exposure time over the whole photon energy range, while the UV-vis absorption spectra of the blend films only show a mild photo-induced bleaching. This demonstrates that not only the photo-induced degradation of the solar cell performance is not predominantly caused by the loss in light absorption, but charge transport and collection are also hampered. This is explained by the fact that photo-oxidation of PC70BM causes bonds in its conjugated cage to break, as evidenced by the decreased ∏* intensity in C1s-NEXAFS spectra of PC70BM films. This degradation of unoccupied states of PC70BM will hinder the transport of photo-generated electrons to the electrode. Surface photovoltage spectroscopy gives direct evidence for gap states at the surface of a PC70BM film, formed after 2 hours of exposure and resulting in upward band bending at the PC70BM/air surface. These observations indicate that the photo-oxidation of PC70BM is likely to be the main cause of the performance degradation observed when the photoactive layer of a TQ1:PC70BM solar cell is intentionally exposed to light in air.

  • 61.
    Blazinic, Vanja
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Ericsson, Leif
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Moons, Ellen
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Stability of TQ1:N2200 active layers for all-polymer solar cellsManuskript (preprint) (Övrigt vetenskapligt)
  • 62.
    Blazinic, Vanja
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Ericsson, Leif
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Muntean, Stela Andrea
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Moons, Ellen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Photo-degradation in air of spin-coated PC60BM and PC70BM films2018Ingår i: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 241, s. 26-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The fullerene derivatives PC60BM and PC70BM are widely used as electron accepting components in the active layer of polymer solar cells. Here we compare their photochemical stability by exposing thin films of PC60BM and PC70BM to simulated sunlight in ambient air for up to 47 h, and study changes in their UV–vis and FT-IR spectra. We quantify the photo-degradation by tracking the development of oxidation products in the transmission FT-IR spectra. Results indicate that PC60BM photodegrades faster than PC70BM. The rate of photo-oxidation of the thin films is dependent on the rate of oxygen diffusion in to the film and on the photo-oxidation rate of a single molecule. Both factors are dependent on the nature of the fullerene cage. The faster photo-oxidation of PC60BM than of PC70BM is in agreement with its slightly lower density and its higher reactivity. The use of PC70BM in solar cells is advantageous not only because of its absorption spectrum, but also because of its higher stability.

    Publikationen är tillgänglig i fulltext från 2020-04-07 11:29
  • 63.
    Boudreau, Jonna
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Mossberg, Magnus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Barbier, Christophe
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Experiments to Find On-line Measurements of the Structure of the Tissue Paper SurfaceArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure of tissue paper has great influence on the quality of the resulting paper produced. One method of measuring the crepe wavelength on-line is sought in order to improve process control as well as to promote greater precision and uniform quality of the end product. In this study, a probe was used to read the surface of the paper whilst the paper travelled at a low speed. Light from a light emitting diode was emitted at a specific angle and collected at the corresponding reflecting angle, from the paper surface.

     

    Focusing the lenses at 45º angle produced results matching closest to the expected wavelength, and such measurements were made on a numerous commercial papers to validate the method. The collected signal contains a lot of information from the surface of the paper and from reflected signals inside the paper. The signal was processed using a mathematical approach to extract the most common wavelengths for each paper. The measured wavelength was found to closely match measurements made with commercial off-line equipment. This new method has a good initial potential to work on-line, however further investigation regarding the effects of high speeds upon the sampling still has to be carried out. 

  • 64.
    Bovin, Jimmy
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Rapid Exchange Solution (RES): En mekanisk omlastningslösning för horisontell överföring av containrar mellan olika transportmedel2013Självständigt arbete på grundnivå (högskoleexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete genomfördes våren 2013 på Karlstads universitet där TD Rail & Industry i Västerås stod som uppdragsgivare. Projektet innefattade att kartlägga nuvarande omlastningslösningar av enhetslaster mellan järnvägstransporter och vägtransporter, och utarbeta en konceptuell omlastningslösning med fokus på att öka järnvägstransporternas flexibilitet gentemot vägtransporterna. Där vikten lades på att utarbeta ett välarbetat helhetskoncept.

    Projektet genomfördes med designprocessen som grund och innehöll bland annat momenten; förstudie, kravspecificering, idégenerering, konceptval m.m.

    Resultatet blev en vidareutveckling av det redan befintliga systemet CCT som bygger på horisontell överföringsteknik och möjliggör därför omlastning av enhetslaster direkt under kontaktledning. Skillnaden mellan RES och CCT är att man tagit bort ombyggnationen av tågvagn och lastbilschassi, som var en av CCTs stora svagheter, genom två hydrauliska ”teknikplattor”. Tack vare detta tillsammans med sin låga investeringskostnad/driftkostnad öppnar RES nya möjligheter för omlastning på fler strategiska punkter direkt utmed järnvägsnätet och därmed ökar järnvägstransporternas flexibilitet.

    Som vidareutveckling av RES föreslås ett samarbete med CCT där man initialt utför mer detaljerade beräkningar på teknikplattorna.

  • 65.
    Brink, Helen
    et al.
    Karlstads universitet.
    Kilbrink, Nina
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Institutionen för pedagogiska studier (from 2013). Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013), Science, Mathematics and Engineering Education Research (SMEER).
    Gericke, Niklas
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Teaching modelling using digital tools in secondary technology education: Teachers’ experiences2019Ingår i: Proceedings PATT37: Developing a knowledge economy through technology and engineering education / [ed] S. Pulé and M. de Vries, 2019, s. 95-102Konferensbidrag (Refereegranskat)
    Abstract [en]

    Models can be used for communicating and for sharing information. In technology education in Swedish compulsory school, pupils have long created models using simple materials to test their designs, such as cardboard and wooden sticks. Models have also been used by teachers to assess pupils’ technology knowledge in particular areas (Elmer & Davies, 2000). We live in a world where technology is highly developed, where digital technology plays an important role and where models are created in digital environments (Kress, 2010). Technology as a school subject undergoes the same development, which can be seen in the technology syllabus (Skolverket, 2011). However, there is a lack of research on technology teachers’ experiences of teaching modelling using digital tools. According to previous research, teachers’ experiences of a phenomenon (Marton & Tsui, 2004) along with their pedagogical and technological knowledge (Mishra & Koehler, 2006) affect how they plan their lessons. The aim of this pilot study is therefore to examine secondary school teachers’ experiences of teaching modelling using digital tools, thereby contributing to understanding this area of technology education. The study takes a phenomenographic approach (Marton & Booth, 1997) and is based on semi-structured interviews with teachers. The interviews are analyzed, focusing on how technology teachers experience teaching modelling using digital tools. Their different experiences are divided into categories. So far, four categories have been identified: a) Modelling using digital tools as inspiration, b) Handling the modelling software as the object of learning, c) Handling 3D printing as the object of learning and d) Modelling for teaching technological content. A tentative result is that teachers have different aims and purposes when teaching modelling using digital tools.

  • 66.
    Brumboiu, Iulia Emilia
    et al.
    KTH Royal Institute of Technology.
    Ericsson, Leif
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Blazinic, Vanja
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Hansson, Rickard
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Opitz, Andreas
    Humboldt-Universität zu Berlin.
    Brena, Barbara
    Uppsala Universitet, Physics and Astronomy.
    Moons, Ellen
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    The Photooxidation of PC60BM: New Insights from SpectroscopyManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In the quest towards more durable solution-processed solar cells, the stability of the active layer materials under operation conditions is important. While lifetimes of several years have been demonstrated for encapsulated organic solar cells, it is generally known that degradation events can be accounted for by air components (O2 and/or water vapour) leaking into the cell through a non-ideal sealing. Here we present a fundamental study of intentional photo-degradation of the electron-acceptor PC60BM ([6,6]-phenyl-C61-butyric acid methyl ester) in air, with the purpose of improving the understanding of the electronic effects of fullerene photo-oxidation. We have studied spincoated thin films of PC60BM by X-ray Photoelectron Spectroscopy, Near-edge X-ray Absorption Fine Structure spectroscopy, and Fourier Transform Infrared Spectroscopy, before and after exposing them to simulated sunlight in air. The changes observed in the spectra obtained by these complementary methods were compared with calculated spectra of a large set of possible oxidation products of PC60BM where oxygen atoms have been attached to the C60 cage. The best fit with experimental IR spectra of photodegraded PC60BM films was obtained for a linear combination of calculated spectra for two degradation products, a dicarbonyl and an anhydride, both with open cages with 58 carbon atoms, and the pristine PC60BM molecule. From this comparison, we conclude that the conjugation of the fullerene cage is disturbed by the formation of several carbonyl-based derivatives on the C60 cage, accompanied by a transition from sp2 to sp3-hybridized carbon. The π* resonance in the C1s NEXAFS spectrum was found to be a very sensitive probe for small changes to the fullerene cage, and FT-IR was needed in combination with O1s NEXAFS, to identify the oxidation products.

  • 67.
    Brumboiu, Iulia Emilia
    et al.
    Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden.
    Ericsson, Leif K.E.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Hansson, Rickard
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Moons, Ellen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Eriksson, Olle
    Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden.
    Brena, Barbara
    Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden.
    The influence of oxygen adsorption on the NEXAFS and core-level XPS spectra of the C60 derivative PCBM2015Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 142, s. 054306-Artikel i tidskrift (Refereegranskat)
  • 68.
    Buchberger, Igor
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Strings, Gravitons, and Effective Field Theories2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis concerns a range of aspects of theoretical physics. It is composed of two parts. In the first part we motivate our line of research, and introduce and discuss the relevant concepts. In the second part, four research papers are collected. The first paper deals with a possible extension of general relativity, namely the recently discovered classically consistent bimetric theory. In this paper we study the behavior of perturbations of the metric(s) around cosmologically viable background solutions. In the second paper, we explore possibilities for particle physics with low-scale supersymmetry. In particular we consider the addition of supersymmetric higher-dimensional operators to the minimal supersymmetric standard model, and study collider phenomenology in this class of models. The third paper deals with a possible extension of the notion of Lie algebras within category theory. Considering Lie algebras as objects in additive symmetric ribbon categories we define the proper Killing form morphism and explore its role towards a structure theory of Lie algebras in this setting. Finally, the last paper is concerned with the computation of string amplitudes in four dimensional models with reduced supersymmetry. In particular, we develop general techniques to compute amplitudes involving gauge bosons and gravitons and explicitly compute the corresponding three- and four-point functions. On the one hand, these results can be used to extract important pieces of the effective actions that string theory dictates, on the other they can be used as a tool to compute the corresponding field theory amplitudes.

  • 69.
    Buchberger, Igor
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik. Karlstads Univ, Teoret Fys, S-65188 Karlstad, Sweden..
    Fuchs, Jürgen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    On the Killing form of Lie Algebras in Symmetric Ribbon Categories2015Ingår i: SIGMA. Symmetry, Integrability and Geometry, ISSN 1815-0659, E-ISSN 1815-0659, Vol. 11, artikel-id 017Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As a step towards the structure theory of Lie algebras in symmetric monoidal categories we establish results involving the Killing form. The proper categorical setting for discussing these issues are symmetric ribbon categories.

  • 70.
    Calles, Linus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Development of ergonomic seating for dental operator chair2017Självständigt arbete på grundnivå (högskoleexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This report covers the examination of course Degree of Bachelor of Science in Innovation and Design MSGC12. The course is given on the Innovation and Design Program at the Faculty of Health, Science and Technology at Karlstad University. The course corresponds to 22.5 credits and extends over the spring semester in 2017. Examiner is Leo de Vin and supervisor is Kristina Gullander.

    The project is carried out on behalf of Support Design AB, which manufactures and distributes handmade ergonomic chairs. The company is aiming primarily at the dental and medical industry, where they have discovered a great interest in flexible and ergonomic chairs. There are today competing brands that manufacture chairs whose seats are similar to Support Designs. The company now wishes to expand its range of seating in order to differ from market competitors. Need for a more concrete foundation in research on sitting in the dental sector is also something they are looking for.

    The assignment therefore consists of developing an ergonomically designed seat for dental operator chairs, which has a strong foundation in research on sitting in the dental industry and has got a unique design.

    The project's pre-study starts with a literature study, with a large emphasis on trying to define what a good and ergonomic sitting posture is. This is done to provide a basis for a subsequent analysis of interviews and observations by dental staff. To survey the needs of the users, 15 interviews are performed with dental staff to gain an insight into their views of the workplaces and existing operator chairs. Structured observations are carried out at 11 patient visits in connection with the interviews to find motion patterns and review their work positions. The result of the preliminary study shows that many in dental care experience or has experienced work-related pain, especially shoulders, neck and back. A wide legged and relatively ergonomic working position is commonly observed in narrow operating rooms.

     

    The project results in 15 different concepts where four qualify for prototype manufacturing and testing. One concept is perceived to be the most comfortable while another is perceived to be the most unique. One concept meets ergonomic criteria best and another does not meet all the important requirements that the pre-study generated. 

  • 71.
    Carlson, Philip
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik, Science, Mathematics and Engineering Education Research (SMEER).
    Konstruktions- och Materialförbättring hos Superkritiska Ventiler2015Självständigt arbete på grundnivå (högskoleexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
  • 72.
    Castellanos, Sergio
    et al.
    Massachusetts Institute of Technology, Camebridge, MA, USA.
    Hofstetter, Jasmin
    Massachusetts Institute of Technology, Camebridge, MA, USA.
    Kivambe, Maulid
    Massachusetts Institute of Technology, Camebridge, MA, USA.
    Rinio, Markus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Lai, Barry
    Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, USA.
    Buonassisi, Tonio
    Massachusetts Institute of Technology, Camebridge, MA, USA.
    Inferring Dislocation Recombination Strength in Multicrystalline Silicon via Etch Pit Geometry Analysis2014Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Dislocations limit solar cell performance bydecreasing minority carrier diffusion length, leading to inefficientcharge collection at the device contacts. However, studieshave shown that the recombination strength of dislocationclusters within millimeters away from each other can vary byorders of magnitude. In this contribution, we present correlations between dislocation microstructure and recombination activity levels which span close to two orders of magnitude. We discuss a general trend observed: higherdislocation recombination activity appears to be correlated witha higher degree of impurity decoration, and a higher degree ofdisorder in the spatial distribution of etch pits. We present anapproach to quantify the degree of disorder of dislocationclusters. Based on our observations, we hypothesize that therecombination activity of different dislocation clusters can bepredicted by visual inspection of the etch pit distribution andgeometry.

  • 73.
    Castellanos, Sergio
    et al.
    Massachusetts Institute of Technology, Massachusetts, USA.
    Kivambe, Maulid
    Massachusetts Institute of Technology, Massachusetts, USA.
    Hofstetter, Jasmin
    Massachusetts Institute of Technology, Massachusetts, USA.
    Rinio, Markus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Lai, Barry
    Argonne Photon Source, Illinois, USA.
    Buonassisi, Tonio
    Massachusetts Institute of Technology, Massachusetts, USA.
    Variation of dislocation etch-pit geometry: An indicator of bulk microstructure and recombination activity in multicrystalline silicon2014Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, nr 18, s. 1-7, artikel-id 183511Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dislocation clusters in multicrystalline silicon limit solar cell performance by decreasing minoritycarrier diffusion length. Studies have shown that the recombination strength of dislocation clusterscan vary by up to two orders of magnitude, even within the same wafer. In this contribution, wecombine a surface-analysis approach with bulk characterization techniques to explore theunderlying root cause of variations in recombination strength among different clusters. We observethat dislocation clusters with higher recombination strength consist of dislocations with a largervariation of line vector, correlated with a higher degree of variation in dislocation etch-pit shapes(ellipticities). Conversely, dislocation clusters exhibiting the lowest recombination strength containmostly dislocations with identical line vectors, resulting in very similar etch-pit shapes. Thedisorder of dislocation line vector in high-recombination clusters appears to be correlated withimpurity decoration, possibly the cause of the enhanced recombination activity. Based on ourobservations, we conclude that the relative recombination activity of different dislocation clustersin the device may be predicted via an optical inspection of the distribution and shape variation ofdislocation etch pits in the as-grown wafer.

  • 74. Chavhan, Sudam D.
    et al.
    Hansson, Rickard
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Ericsson, Leif
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Beyer, Paul
    Hofmann, Alexander
    Brütting, Wolfgang
    Opitz, Andreas
    Moons, Ellen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Low temperature processed NiOx hole transport layers for efficient polymer solar cells2017Ingår i: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 44, s. 59-66Artikel i tidskrift (Refereegranskat)
  • 75.
    Ciammaruchi, Laura
    et al.
    Parc Mediterani de la Technologia, ICFO.
    Hansson, Rickard
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Moons, Ellen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Galagan, Yulia
    TNO Solliance, Eindhoven, Netherlands.
    Stability of organic solar cells with PCDTBT donor polymer: An interlaboratory study2018Ingår i: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 33, nr 13, s. 1909-1924Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work is part of the interlaboratory collaboration to study the stability of organic solar cells containing PCDTBT polymer as a donor material. The varieties of the OPV devices with different device architectures, electrode materials, encapsulation, and device dimensions were prepared by seven research laboratories. Sets of identical devices were aged according to four different protocols: shelf lifetime, laboratory weathering under simulated illumination at ambient temperature, laboratory weathering under simulated illumination, and elevated temperature (65 degrees C) and daylight outdoor weathering under sunlight. The results generated in this study allow us to outline several general conclusions related to PCDTBT-based bulk heterojunction (BHJ) solar cells. The results herein reported can be considered as practical guidance for the realization of stabilization approaches in BHJ solar cells containing PCDTBT.

  • 76.
    Cirillo, Emilio N.M.
    et al.
    Sapienza Universit`a di Roma, Italy.
    Colangeli, Matteo
    Moons, Ellen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Muntean, Adrian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Muntean, Stela Andrea
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    van Stam, Jan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    A lattice model approach to the morphology formation from ternary mixtures during the evaporation of one component2019Ingår i: The European Physical Journal Special Topics, ISSN 1951-6355, E-ISSN 1951-6401, Vol. 228, nr 1, s. 55-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stimulated by experimental evidence in the field of solution-born thin films, we study the morphology formation in a three state lattice system subjected to the evaporation of one component. The practical problem that we address is the understanding of the parameters that govern morphology formation from a ternary mixture upon evaporation, as is the case in the fabrication of thin films from solution for organic photovoltaics. We use, as a tool, a generalized version of the Potts and Blume-Capel models in 2D, with the Monte Carlo Kawasaki-Metropolis algorithm, to simulate the phase behaviour of a ternary mixture upon evaporation of one of its components. The components with spin 1, −1 and 0 in the Blume-Capel dynamics correspond to the electron-acceptor, electron-donor and solvent molecules, respectively, in a ternary mixture used in the preparation of the active layer films in an organic solar cell. Furthermore, we introduce parameters that account for the relative composition of the mixture, temperature, and interaction between the species in the system. We identify the parameter regions that are prone to facilitate the phase separation. Furthermore, we study qualitatively the types of formed configurations. We show that even a relatively simple model, as the present one, can generate key morphological features, similar to those observed in experiments, which proves the method valuable for the study of complex systems.

  • 77.
    Daane, Abigail R.
    et al.
    Department of Physics, South Seattle College,Seattle, Washington.
    Haglund, Jesper
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Robertson, Amy D.
    Department of Physics, Seattle Pacific University, Seattle, Washington.
    Close, Hunter G.
    Department of Physics, Texas State University, San Marcos, Texas.
    Scherr, Rachel E.
    Department of Physics, Seattle Pacific University, Seattle, Washington.
    The pedagogical value of conceptual metaphor for secondary science teachers2018Ingår i: Science Education, ISSN 0036-8326, E-ISSN 1098-237X, Vol. 102, nr 5, s. 1051-1076Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The abstract nature of energy encourages metaphorical language. In educational settings, teachers and students use conceptual metaphors subconsciously to express their ideas about what energy is or how it functions in particular scenarios. However, research on scientific analogies and metaphors has predominantly focused on explicit instructional analogies, rather than implicit, everyday metaphor. In professional development for secondary science teachers, we sought to make explicit the embeddedness and ubiquity of conceptual metaphor in everyday language and in scienceparticularly, in energyto expand teachers' understanding of their students' ideas. In our microcase study, we observed and video recorded four secondary teachers discussing metaphor. We used interaction analysis methods, focusing on how both discursive and nonverbal interactions between people, objects, and environment change over time, to analyze the collected data. We found evidence of teachers' (1) learning about conceptual metaphor theory and (2) finding value in understanding conceptual metaphor in educational settings. In particular, teachers acknowledged that if they identify implicit metaphors in students' science language, they will better understand students' ideas about energy. We present possible mechanisms for teacher learning about and valuing of energy metaphor; we also suggest how to support teachers in noticing and valuing metaphors for energy instruction.

  • 78.
    Dahlin, Cecilia
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    De yngsta barnens möten med fysikaliska fenomen i förskolan: En undersökning om hur pedagogerna ger de yngsta barnen möjlighet att utforska och undersöka enkla fysikaliska fenomen2014Självständigt arbete på avancerad nivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Skolinspektionen visar i skolverkets kvalitetsgranskning, rapport 2012:7 att majoriteten av pedagogerna i Svenska förskolorna behöver utvidga sina kunskaper om hur de kan arbeta med naturvetenskap och hur de kan stimulera och utmana barnens nyfikenhet och lärande inom området. Studier visar även att förskollärare ofta är oroliga för att ställa frågor och svara på frågor om naturvetenskap på grund av egna kunskapsbrister. I studien har jag begränsat mig till att endast undersöka hur de yngsta barnen får möjlighet att utveckla förståelse och kunnande om fysikaliska fenomen. Syftet med studien är att synliggöra om och hur pedagoger går tillväga för att skapa möten mellan barnen och fysikaliska fenomen, för att främja förståelse och kunskap. Studiens resultat baseras på kvalitativa intervjuer med tio stycken förskollärare.

    Resultatet visar att majoriteten av respondenterna gav barnen möjligheter att utveckla förståelse och kunskap om fysikaliska fenomen. Antigen genom planerade aktiviteter eller oplanerade aktiviteter, men de fanns även de som inte gav barnen den möjligheten alls. Resultatet visar även att respondenterna inte uppfattade barnens utforskande som ett vetenskapligt utforskande. Inte heller att deras arbete gav stöd till barnen att utveckla sina förmågor att arbeta vetenskapligt genom att hjälper barnen i att öva på att ställa produktiva frågor, ställa hypoteser och sedan undersöka dem, vilket utgör grunden i ett vetenskapligt arbetsätt. 

  • 79.
    Daouacher, Maria
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik, Science, Mathematics and Engineering Education Research (SMEER).
    Rearward facing travel for every child's safety2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This study was made within the Child Safety group at Volvo Car Corporation.  The purpose of this bachelor thesis was to study the different aspects of rearward facing child restraint systems, which is the safest way for small children to travel, in order to suggest improvements in the development of child restraint systems. The studies included scientific articles regarding child safety and fatally injured children in car accidents, both in Sweden and internationally. The overall aim is to find factors that enables the increase in usage of rearward facing child restraint systems, including the increase of usage time to as long as possible.

     

    Swedish accident data, obtained by the Swedish Traffic Data Acquisation, was studied. It was found that the fatally injured children during car accidents in Sweden between the years 2000-2016 commonly were involved in extraordinarily accident scenarios with an outcome independent of how they were restrained. The literature study and the survey that was made were both supporting the statement of inconvenience while using rearward facing child restraint systems. The inconvenience often corresponded to different types of misuse. The main issue with rearward facing according to the responding parents was lack of leg space, both for their child but also for the driver and the front seat passenger. These issues made some parents turning their children forward facing at early age, whereas they could still fit in the rearward facing child restraint system.

     

    One key in order to increase the global use of rearward facing child restraint systems lies in changes of the materials and design. A more lightweight and compact design is suggested, providing a more spacious travel environment for the children and easier mounting for the parents. The need of education is apparent, preferable by means of social media due to the easiness of sending information globally with low cost.

  • 80.
    De Vin, Leo
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Plagiering: en moralisk fråga eller en pedagogisk utmaning?2012Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Artikeln beskriver plagiat men även otillåtet samarbete. Uppfattningarna om vad som räknas till plagiat varierar dock. Plagiat är inte lika med fusk, för fusk krävs uppsåt att vilseleda. Plagiat uppstår ofta när studenter känner tidspress eller osäkerhet. Lärare brukar upptäcka indikeringar på möjligt plagiat på manga olika sätt, det är relativt sällan att antiplagieringsverktyg larmar utan att läraren redan har fått misstankar. Sättet som plagiat hanteras på beror på ett antal faktorer, till exempel om studenten vet om korrekt källhantering eller ej. Inte alla fall av plagiat blir ärenden för disciplinsnämnden. Som lärare kan man förebygga plagiat på olika sätt. Dels handlar det om information och träning för studenter, dels handlar det om utformning av examinationsuppgifter, till exempel variation av uppgifter och muntlig återkoppling.

  • 81.
    De Vin, Leo
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Simulation, Models, and Results: Reflections on their Nature and Credibility2015Ingår i: Proceedings of Flexible Automation and Intelligent Manufacturing, FAIM2015, Wolverhampton, UK / [ed] Chike F. Oduoza, Wolverhampton, UK: The Choir Press , 2015, s. 148-155Konferensbidrag (Refereegranskat)
    Abstract [en]

    Simulation tools are widely used across the product, process and resource domains of product- and production development. This paper discusses the nature of simulation models and the wide use of simulation models .It uses virtual manufacturing, in particular discrete event simulation project methodology, as an example to elucidate important aspects of simulation, in particular human roles and some selected project phases of which verification and validation in relation to the simulation’s intended purpose are discussed in particular. The paper uses the NASA CAS model for credibility assessment of simulations to arrive at a schematic representation of how overall credibility as composed of aspect related to the model, the data, and the model’s use.

  • 82.
    De Vin, Leo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Jacobsson, Lasse
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Karlstad Lean Factory: An instructional factory for game-based lean manufacturing training2017Ingår i: Production & Manufacturing Research, ISSN 2169-3277, Vol. 5, nr 1, s. 268-283Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simulation for training lean manufacturing ranges from simple paper-based or LEGO®-based games to larger scale simulation environments, for instance push car assembly. Some models for game-based learning are discussed and a model for lean manufacturing training is adopted . Many types of simulation may be suitable for teaching some basic elements of Lean manufacturing to students, but they are often less suitable for training industry workers in applying Lean manufacturing in their work environment. The latter group is more used to intuitive learning than to formal instruction. Thus, it is important that a training environment for this group more realistically represents the work environment; otherwise training transfer will be limited. For this reason, a lean training environment that includes materials processing stations as well as assembly areas was created. The stations exhibit some realistic behaviour such as stochastic breakdowns. Based on a comparison between factory workers and university students, five hypotheses for testing in future work are proposed.

  • 83.
    De Vin, Leo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Jacobsson, Lasse
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Odhe, JanErik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Game-based Lean Production training of university students and industrial employees2018Ingår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 25, s. 578-585Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Production simulation games are increasingly popular for training students and industrial employees in Lean Production principles. They range from paper- or desktop-based games to full scale simulators and proper manufacturing machinery. This paper reports on experiences from using both desktop games and a full scale simulator. Desktop games are suitable when training people who already have a fair understanding of lean principles. Shop floor workers usually have difficulties in seeing analogies between desktop games and their work environment. For both students and industrial workers, training effects and immersion tend to be higher when using full scale simulators.

  • 84.
    De Vin, Leo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Jacobsson, Lasse
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Odhe, JanErik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Simulator-assisted lean production training2019Ingår i: Production & Manufacturing Research, ISSN 2169-3277, Vol. 7, nr 1, s. 433-447Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Lean Production training and education, simulators are often used.These can take the form of for instance desktop games, computersimulations, or full-scale simulators. Many training participants perceivemodels for experiential learning and for continuous improvementprocesses as complex and abstract. Based on experiences from trainingsessions in a full-scale simulator Karlstad Lean Factory®, a unifiedmodelfor learning and improvementwork is presented. Thismodel stimulatestraining transfer and is perceived as intuitive. It also shows instructionalscaffolding as a learning method. Suggestions for future work includeinvestigating synergy with Smart Manufacturing and the use of LeanProduction simulators for innovative product realisation.

  • 85.
    De Vin, Leo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Jacobsson, Lasse
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Odhe, JanErik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Simulator-Assisted Lean Production Training and Education2018Ingår i: Advaces in manufacturing technology / [ed] P. Thorvald and K. Case, Amsterdam: IOS Press, 2018, Vol. XXXII, s. 487-492Konferensbidrag (Refereegranskat)
    Abstract [en]

    In Lean Production training and education, simulators are often used. These can take the form of for instance desktop games, computer simulations, or full-scale simulators. Most evidence of training transfer from the training environment to the work situation is anecdotal, and as such is assessment of training transfer a research gap. Experiences from training sessions in Karlstad Lean Factory® are presented, including a combination with computer simulation. A unified model for learning and improvement work is presented. Some suggestions for future work include investigating synergy with Smart Manufacturing and/or innovative product realization.

  • 86.
    De Vin, Leo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Jacobsson, Lasse
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Odhe, JanErik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Wickberg, Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Lean Production Training for the Manufacturing Industry: Experiences from Karlstad Lean Factory2017Ingår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 11, artikel-id 1019-1026Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Both literature and manufacturing companies state that simulators for providing training in lean production to industrialemployees must be similar to the work environment. This motivated the design of Karlstad Lean Factory, which is a trainingenvironment that realistically resembles an industrial environment. It is a full-scale training facility that incorporates acombination of materials processing and assembly. Parameters such as processing times, breakdown intervals and repair typescan be set. Examples of basic and more advanced training scenarios are given. Experiences from training groups of industrialemployees are described; inhomogeneity of these groups requires some specific attention.

  • 87.
    De Vin, Leo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Ng, Amos
    Högskolan i Skövde.
    Editorial2009Ingår i: International Journal of Sustainable Engineering, ISSN 1939-7038, E-ISSN 1939-7046, Vol. 2, nr 2, s. 79-79Artikel i tidskrift (Övrigt vetenskapligt)
  • 88.
    De Vin, Leo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Ng, AmosThorvald, PeterSullivan, WilliamAhmad, Munir
    Proceedings of the 18th International Conference on Flexible Automation and Intelligent manufactring: FAIM 2008 June 30th – July 2nd, 2008 University of Skövde, Sweden2008Proceedings (redaktörskap) (Övrigt vetenskapligt)
  • 89.
    De Vin, Leo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Odhe, JanErik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Jacobsson, Lasse
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Säfström, Mattias
    IUC Värmland / Stål & Verkstad.
    Lean Production Simulators: From Training Environments to Innovation Testbeds2019Ingår i: Advances in Manufacturing Technology XXXIII / [ed] Y. Jin and M. Price, Amsterdam: IOS Press, 2019, s. 461-466Konferensbidrag (Refereegranskat)
    Abstract [en]

     Models for continuous improvement processes and for game-based learning currently have some drawbacks. Based on work with Karlstad Lean Factory®, a dual model for game-based learning and improvement processes is presented. This model also shows instructional scaffolding, and there is evidence that its use stimulates training transfer. A natural step is to extend the use of fullscale lean production simulators to a novel use as innovation testbeds. This can lower the threshold for production innovation in SMEs. A small case study shows how this novel use can be organised, with several benefits for the company.

  • 90.
    De Vin, Leo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Solis, JorgeKarlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Proceedings of the 14th Mechatronics Forum International Conference Mechatronics 20142014Proceedings (redaktörskap) (Refereegranskat)
  • 91.
    Deekoo, Maryam
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    NTA-Lådor i kemiundervisning: Elevers förståelse av kemi vid två typer av undervisning i årskurs 4.2019Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This study is about pupils’ perception and interest in the chemistry topic and their understanding of the content of the lessons. This is made by studying pupils’ understanding and motivation based on two lessons in chemistry, a theoretical lesson and a practical lesson. The pupils’ get more curious about the subject of chemistry and environment when working with NTA-box. Eight pupils divided into two groups with four in each, have been interviewed in this study. The pupils in the first group have read a factual text in the science book about red cabbage juice and answered some questions about it. The second group have examined the chemical properties of some substances with the help of red-cabbage juice. The results from the pupil’s answers has shown that motivation of second group was higher, because most pupils thought that laboratory work is fun and they have learned a lot from the studies. However, the pupils who have read the book have been able to understand the text and explain their answers in a clear way.

  • 92.
    Denker, Richard
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Dimensioning and control for heat pump systems using a combination of vertical and horizontal ground-coupled heat exchangers2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A model has been developed which simulates a system consisting of a horizontal and vertical ground-coupled heat exchanger connected in parallel to the same heat pump. The model was used in computer simulations to investigate how the annual minimum and mean fluid temperatures at the heat pump varied as several parameters of the combined system were changed. A comparison was also made between different control settings for fluid flow rate distribution between the two exchangers. For the case when the flow rate distribution was not controlled, the effect of viscosity differences between a colder and warmer exchanger was investigated. The short term effects of letting the vertical heat source rest during the warm summer months was then tested. Lastly, the results of the model was compared to a simple 'rule of thumb' that have been used in the industry for this kind of combined system. The results show that using a combined system might not always result in increased performance, if the previously existing exchanger is a vertical ground-coupled heat exchanger. The effects of viscosity differences on the flow distribution seems to be negligible, especially for high net flows. Controlling the fluid flow rates seems to only be worth the effort if the the pipe lengths of the two combined exchangers differ heavily. Letting the vertical ground-coupled heat exchanger rest during summer was shown to in some cases yield an increased short-term performance in addition to the already known positive long term effects. The rule of thumb was shown to recommend smaller dimensions for combination systems than the more realistic analytical model.

  • 93.
    Dolo, Gilbert
    et al.
    University of Cape Town, Sydafrika.
    Haglund, Jesper
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013). SMEER.
    Schönborn, Konrad J.
    Linköpings universitet.
    Thermal cameras as a semiotic resource for inquiry in a South African township school context2018Ingår i: Designs for Learning, ISSN 1654-7608, Vol. 10, nr 1, s. 123-134Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inquiry-based approaches to science education are central to recent South African primary and secondary school curricula, but have been found challenging to adopt in disadvantaged township contexts. It is therefore important to find ways of introducing inquiry-based approaches, where pupils are encouraged to investigate phenomena they are interested in and to engage in true dialogue, as opposed to teacher-led triadic dialogue. We typically experience thermal phenomena through the sense of touch, but infrared (IR) cameras provide an additional opportunity to experience heat-related phenomena through the visual sense. Previously, in a Swedish context, we have found that hand-held IR cameras allow for strong pedagogical affordances and inspire pupils to engage in inquiry in the area of thermal science. In the present case study, grade 7 and 8 pupils (13–14 years old) in two South African township schools were introduced to IR cameras during predict-observe-explain (POE) exercises on heat conduction. The results revealed that if pupils had a sufficient conceptual understanding of heat conduction beforehand, they were capable of engaging in true dialogue in relation to the exercises and interpreting the thermal camera visual imagery. However, if pupils did not show such understanding, it was tempting for them and the facilitator to resort to triadic dialogue.

  • 94.
    Dou, Yangpeng
    et al.
    China.
    Peng, Junjun
    China.
    Li, Wei
    China.
    Li, Ming
    China.
    Liu, Huihong
    China.
    Zhang, Hanmin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Effects of reducibility of graphene oxide nanosheets on preparation of AgNPs/GO nanocomposites and their electrocatalytic performance2015Ingår i: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 17, nr 12, s. 1-10, artikel-id 489Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silver nanoparticles/graphene oxide (AgNPs/GO) nanocomposites were prepared in a solution of AgNO3 and GO. The GO serves not only as a reductant but also as a substrate to support the as-reduced silver nanoparticles. The reducibility of GO was investigated by analyzing the influence factors such as pH, duration, the reaction temperature, and the weight ratio of AgNO3 and GO in the AgNP/GO nanocomposite mixture, which were evaluated by the UV–vis absorption spectroscopy. The results demonstrated that Ag nanoparticles with an average diameter of 5–10 nm were uniformly dispersed on the surface of GO nanosheets under the optimum synthesis conditions of pH between 8 and 11, weight ratio of AgNO3 and GO between 55 % and 60 %, and at 80 °C for 6 h. Moreover, the obtained AgNPs/GO nanocomposites exhibit good electrocatalytic activity for the reduction of p-nitrophenol to 4-(hydroxyamino) phenol.

  • 95.
    Dzogbewu, Thywill
    et al.
    Department of Mechanical and Mechatronic Engineering, Bloemfontein, Central University of Technology, Free State, South Africa.
    Yadroitsev, Igov
    Department of Mechanical and Mechatronic Engineering, Bloemfontein, Central University of.
    Krakhmalev, Pavel
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Yadroitsava, Inna
    Department of Mechanical and Mechatronic Engineering, Bloemfontein, Central University of.
    Du Plessis, Anton
    University of Stellenbosch.
    Optimal process parameters for in-situ alloyed Ti15Mo structures by Direct Metal Laser Sintering2017Ingår i: Solid Freeform Fabrication 2017: Proceedings of the 28th Annual InternationalSolid Freeform Fabrication Symposium – An Additive Manufacturing Conference, Austin: University of Texas , 2017, s. 75-96Konferensbidrag (Refereegranskat)
  • 96.
    Edvardsson, Elisabet
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Band structures of topological crystalline insulators2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Topological insulators and topological crystalline insulators are materials that have a bulk band structure that is gapped, but that also have toplogically protected non-gapped surface states. This implies that the bulk is insulating, but that the material can conduct electricity on some of its surfaces. The robustness of these surface states is a consequence of time-reversal symmetry, possibly in combination with invariance under other symmetries, like that of the crystal itself. In this thesis we review some of the basic theory for such materials. In particular we discuss how topological invariants can be derived for some specific systems. We then move on to do band structure calculations using the tight-binding method, with the aim to see the topologically protected surface states in a topological crystalline insulator. These calculations require the diagonalization of block tridiagonal matrices. We finish the thesis by studying the properties of such matrices in more detail and derive some results regarding the distribution and convergence of their eigenvalues.

  • 97.
    Edvardsson, Elisabet
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Quasicrystals: Classification, diffraction and surface studies2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Quasicrystal is the term used for a solid that possesses an essentially discrete diffraction pattern without having translational symmetry. Compared to periodic crystals, this difference in structure gives quasicrystals new properties that make them interesting to study -- both from a mathematical and from a physical point of view. In this thesis we review a mathematical description of quasicrystals that aims at generalizing the well-established theory of periodic crystals. We see how this theory can be connected to the cohomology of groups and how we can use this connection to classify quasicrystals. We also review an experimental method, NIXSW (Normal Incidence X-ray Standing Waves), that is ordinarily used for surface structure determination of periodic crystals, and show how it can be used in the study of quasicrystal surfaces. Finally, we define the reduced lattice and show a way to plot lattices in MATLAB. We see that there is a connection between the diffraction pattern and the reduced lattice and we suggest a way to describe this connection.

  • 98.
    Ekhagen, Sebastian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Stability of electron acceptor materials for organic solar cells: a work function study of C60/C70 derivatives and N22002019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Thin films of the fullerenes PC60BM and PC70BM and the non-fullerene N2200, three popular electron acceptor materials in organic photovoltaics, have been studied, using both the Kelvin probe method as well as ultraviolet photoelectron spectroscopy. With these methods the work function was measured, as well as the highest occupied molecular orbital (HOMO) onset. Additionally band bending effects were studied by illuminating the samples while measuring the work function with the Kelvin probe so called surface photovoltage. Sample of each material was exposed to either air and simulated sunlight or N2 and simulated sunlight, for different length of time, to observe how the materials work function evolves after exposure to the different conditions. It was observed that, as expected from previous studies, that PC60BM was less photo-stable than PC70BM. Additionally, the work function of PC60BM changed significantly by storage in N2. Each material after exposure for 24h to air and light, was annealed and measured with the Kelvin probe. A restoring effect was observed,  for the non-fullerene material N2200. All three materials developed an increasing surface photovoltage, which suggest increased band bending, when exposed to air and light, indicating that due phot-oxidization, charges are redistributed at the surface of the film. The fullerenes showed a larger surface photovoltage effect than the non-fullerene materials. A difference between the work function values obtained from the Kelvin probe method and the ultraviolet photoelectron spectroscopy could be seen, however the exact reason for this couldn't be isolated within this thesis, but was discussed.

  • 99.
    Ekström, Camilla
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Vibrationsdämpning av svarvbom2014Självständigt arbete på grundnivå (yrkesexamen), 180 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Rapporten består utav en teoretisk undersökning kring hur vibrationer i en svarvbom vid resonans kan dämpas på ett enkelt sätt. CS Produktion, för vilka undersökningen gjorts, har velat öka sin invändiga bearbetning från 1,5 m till 2,5 m. Med så långa överhäng på en bom är det risk för resonansvibrationer som ger dålig ytfinhet och kan i värsta fall skada maskin och personal. Bom och infästning har arbetats fram i ett tidigare arbete, efter arbetet kvarstod utvecklandet av en lösning för dämpningen av bommen.

    Problemet har undersökts teoretiskt avseende två möjligheter, utifrån om störfrekvensen träffar en eller flera egenfrekvenser för bommen. Störfrekvensen uppstår från den skärande bearbetningen och måste mätas upp för att senare kunna avgöra vilket av de två fallen som är lämpligt att utgå ifrån.

    Den första modellen för en träff av egenfrekvensen är en inre stång med en vikt i den fria änden av stången, med den andra änden inskruvad i bommens ändplatta. Anordningen beräknas så att egenfrekvensen sammanfaller med bommens egenfrekvens som är i riskområdet för resonans. Den inre anordningen fungerar som massdämpare.

    Den andra modellen för flera träffar av egenfrekvenserna har två lösningar som beror på hur bommen beter sig vid ingrepp. Grunden är ett inre rör som kan liknas vid en mindre version av bommen för att den ska få liknande egenskaper. Röret beräknas så att det får likvärdiga egenfrekvenser som bommen och kommer då följa modellen för ett system med två frihetsgrader vid resonans. För varje egenfrekvens på bommen ger röret en vibrationsdämpande effekt vid resonansområdena.

    Projektet visar att empiriska mätningar behöver göras för att med säkerhet kunna avgöra hur problemet ska avhjälpas. Med mätningar kan också koncepten vidareutvecklas, alternativt ligga till grund för att ta fram mer avancerade lösningar.

  • 100.
    Emanuelsson, Christian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Electronic Structure and Film Morphology Studies of PTCDI on Metal/Semiconductor Surfaces2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Organic semiconductors have received increasing attention over the last decades as potential alternatives for inorganic semiconductors. The properties of these films are highly dependent on their structural order. Of special interest is the interface between the film and its substrate, since the structure of the interface and the first few layers decide the growth of the rest of the film. The interface structure is determined by the substrate/molecule interactions, the intermolecular interactions and the growth conditions.

    In this thesis, thin films of the organic semiconductor PTCDI have been studied using complementary microscopy and spectroscopy techniques on two metal-induced surface reconstructions, Ag/Si(111)-√3×√3 and Sn/Si(111)-2√3×2√3. These surfaces were chosen because they have different reactivities and surface periodicities. On the weakly interacting Ag-terminated surface, the film growth is mainly governed by the intermolecular interactions. This leads to well-ordered films that grow layer-by-layer. The interaction with the substrate is through electron charge transfer to the molecules from the substrate. This results in two different types of molecules with different electronic structure, which are identified using both STM images and PES spectra. On the more strongly interacting Sn-terminated surface the molecules adsorb in specific adsorption geometries and form 1D rows. At around 0.5 ML coverage the rows also interact with each other and form a 4√3×2√3 reconstruction and beyond one ML coverage the growth is characterized as island growth. The interaction with the substrate is mainly due to heavy electron charge transfer from the Sn atoms in the substrate to the C atoms in the imide group, but also the N atoms and the perylene core in PTCDI are involved. In these systems, the interactions with the surfaces result in new states inside the HOMO-LUMO gap, and the intermolecular interactions are dominated by O···H and O···H-N hydrogen bondings.

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