<p>The aim of the present work was to clarify the mechanisms of hydrogen removal during vacuum degassing. The main reason for this was because the primary source of hydrogen pick-up in steel-making is the moisture in the furnace atmosphere and the raw material charged into the ladle furnace. Previous studies showed that the presence of hydroxyl ions in the ladle slag results in hydrogen transfer from the slag back into the steel bath. The main focus of this thesis was therefore to gain deeper knowledge of the ladle slag and its properties. For this purpose a number of slag compositions were examined in order to clarify whether these slags were single liquids at 1858 K. 14 out of 27 compositions in the Al₂O₃ CaO MgO SiO₂system was completely melted. These results were in disagreement with the existing phase diagrams.</p><p>Water solubility measurements were carried out by employing a thermo gravimetric technique. The temperature was found to have negligible effect on the water solubilities. The experimental results showed that the water capacity values varied between 1x10³and 2x10³ in the majority of the composition range. However, for compositions close to CaO saturation the water capacity value could reach higher than 3x10³. The experimental determined water capacity was further used to develop a water capacity model for the quaternary slag system Al₂O₃CaO MgO SiO₂. The model was constructed by considering the affects of the binary interactions between the cations in the slag on the capacity of capturing hydroxyl ions. The model calculations agreed well with the experimental results as well as with the literature data.</p><p>An attempt was made to develop a preliminary process model for dehydrogenation by using the results from CFD calculation. For this purpose industrial sampling was made during vacuum treatment. The hydrogen concentrations decreases fast in the initial stages of the degassing, but is slowed down in the final stage. The model calculations fit the initial stage of the dehydrogenation process well. In the final stage of the process the predicted values are somewhat lower than the plant data. The results from the model prediction showed that a dynamic process model could be satisfactorily constructed using the results from CFD calculation.</p><p>The present work aimed at determining how big impact hydroxyl ions in the slag have on the final hydrogen concentration in the liquid steel. It was found that the effect is of less importance regarding the final concentration of the metal after the degassing treatment.</p>

<p>This thesis deals with physiological and mechanical properties of fast and slow twitch mouse muscles. It discusses isometric, concentric and eccentric contractions of mouse <i>extensor digitorum longus</i> ('EDL') and <i>soleus</i> ('SOL') muscles. This project primarily investigated the behaviors of muscles, to give better understanding and improved descriptions for the human system, when subjected to impact or sustained high loading conditions.</p><p>Muscle force has been shown to be length and activation dependent. The effect of passive or active length changes on muscle force production was studied. Isometric activation showed a maximal force at optimum length for each individual muscle, to which all experiments were related. This optimum length was stimulation frequency dependent and maximum produced force shifted towards shorter length with increasing frequency.</p><p>Active shortening of maximally stimulated muscle was shown to produce reduced force, but also a reduced isometric force (force depression) following shortening, regardless of the shortening conditions and the method of muscle stimulation.</p><p>Steady state force depression (Δ<i>F</i>_stdep) was correlated with the instant force depression Δ<i>F</i>_idep, pre-activation time, t0-t1 and the work (WS), performed by the muscle during shortening. It was positively correlated with the Δ<i>F</i>_idep when the shortening magnitude was varied ('VSM'). But in varying the shortening velocity ('VST'), it was negatively correlated with the instant force depression.</p><p>In active stretch, force was analogously enhanced during stretch, and this effect remained after stretch. Steady state force enhancement (Δ<i>F</i>_stenh)following muscle stretch was correlated with the instant force enhancement,Δ<i>F</i>_ienh, pre-activation time, t0-t1 and the work (WL), done on the muscle during stretch. It was positively correlated with Δ<i>F</i>_ienh when the stretch magnitude was varied ('VLM'). But in varying the stretch velocity ('VLT'), Δ<i>F</i>_stenh was negatively correlated with Δ<i>F</i>_ienh.</p><p>Furthermore, the rise time constant, (<i>Tr)</i> of redeveloped isometric forces following the</p><p>shortening and the fall time constant, (<i>Tf)</i> of the relaxed isometric force following muscle stretch were calculated. In VSM, <i>Tr</i> and<i> F</i>_stdep were positively correlated with each other, while in VST, they were negatively correlated. <i>Tf</i> and <i>F</i>_stenhwere negatively correlated in both VLM and VLT.</p>

<p>Lead chalcogenides and tin chalcogenides and their alloys are IV−VI family semiconductors with unique material properties compared with similar semiconductors. For instance, Pb<i>Y </i>(<i>Y </i>= S, Se, and Te) are narrow-gap semiconductors with anomalous negative pressure coefficient and positive temperature coefficient. It is known that this behavior is related with the symmetry of wave functions in first Brillouin zone L-point, which moves the edges of valence band maximum and conduction band minimum towards each other with pressure increasing. SnTe has opposite behavior since its wavefunction symmetry is different from Pb<i>Y</i>. Therefore, by alloying PbTe and SnTe one can change and control the band gap energy and its pressure or temperature dependence. These chalcogenides alloys have therefore a huge potential in industrial low-wavelength applications and have been attracted the attention of researchers.</p><p>This thesis comprises theoretical studies of Pb<i>Y</i>, Sn<i>Y</i> (<i>Y </i>= S, Se and Te) and the Pb₁−<i>x</i>Sn<i>x</i>Te alloys (<i>x</i>= 0.00, 0.25, 0.50, 0.75, and 1.00) by means of a first-principles calculation, using the full-potential linearized augmented plane waves method and the local density approximation.</p><p>The optical properties of Pb₁−<i>x</i>Sn<i>x</i>Te alloys are investigated in terms of the dielectric function <i>ε</i>(<i>ω</i>) = ε₁(<i>ω</i>) + <i>iε</i><i>2</i><i>(ω</i>). We find strong optical response in the 0.5–2.0 eV region arising from optical absorption around the LW-line of the Brillouin zone. The calculated linear optical response functions agree well with measured spectra from ellipsometry spectroscopy performed by the Laboratory of Applied Optics, Linköping University. The calculations of the electronic band-edges of the binary PbY and SnY compounds, show similar electronic structure and density-of-states, but there are differences of the symmetry of the band-edge states at and near the Brillouin zone L-point. PbY have a band gap of E<i>g</i><i> </i>0.15−0.30 eV. However, SnY are zero-gap semiconductors<i> E</i><i>g</i> = 0 if the spin-orbit interaction is excluded. The reason for this is that the lowest conduction band and the uppermost valence band cross along the LW line. When including in Pb<i>Y</i>. Although Pb<i>Y</i> and Sn<i>Y </i>have different band-edge physics at their respective equilibrium lattice constants, the change of the band-edges with respect to cell volume is qualitatively the same for all six chalcogenides. The calculations show that the symmetry of band edge at the L-point changes when lattice constant varies and this change affects the pressure coefficient. the spin-orbit interaction a gap <i>E</i><i>g</i><i> </i>≈ 0.2 eV is created, and hence this gap is induced by the spin-orbit interaction. At the L-point, the conduction-band state is a symmetric state and the valence-band state is antisymmetric thereby the L-point pressure coefficient ⁺₄L−₄Lp<i>E</i><i>g</i>∂∂/)L( in SnY is a positive quantity. In contrast to Sn<i>Y</i>, the Pb<i>Y</i> compounds have a band gap both when spin-orbit coupling is excluded and included; this gap is at the L-point, and the conduction-band state has and the valence-band state has symmetry, and thereby this band edge yields the characteristic negative pressure coefficient ⁺₄L−₄Lp<i>E</i><i>g</i>∂∂/)L(</p>

No description available.

<p>In our daily life we are surrounded by different kind of risks and we constantly strive for better methods to quantify and in the prolongation manage these risks. Every activity involves some risks and there are some kinds of risks and some level of risks that we are unwilling to accept. We all like to live a life that is free from risks, but that is impossible.</p><p>The word risk has a lot of different interpretations. In this thesis we shall let risk stand for the combination of random or uncertain events with negative consequences for human health, life and welfare and for the environment together with some measures of the likelihood of such events. We believe this is the prevailing concept or understanding of risk; as the probability of an event followed by some negative consequences or activities of that event.</p><p>In risk analysis one tries to recognize the nature of various risks and to assess the magnitude of the risks. In the risk analysis it is very important to know what system to consider and this is not self evident in many cases. The situation is clearly different for planning and/or building a system compared with running the same system in a real time state. The system that is going to be the subject to the risk analysis must be clearly defined and the limitations and the boundaries of the system must be set. It is very important to ensure that all persons involved in a risk analysis have a common understanding of the system being considered, including relevant operations.</p><p>During the past decades many studies have been carried out on risk related topics and the society has showed a significant interest in the field of risk analysis. Risk analysis is the interdisciplinary field of science that combines results and knowledge of probability theory, mathematical statistics, engineering, medicine, philosophy, psychology, economics and other applied disciplines.</p><p>In this thesis we will give some examples of different risk analyses carried out basically within two areas. The first part of the thesis (paper 1- paper V) describes different risk analyses carried out in the area of transportation. This is an area with large differences between the different modes of transportation in respect to, for example number of users, number of accidents, magnitude of the accidents and accessible data. The latter part of the thesis (paper VI and paper VII) describes two risk analyses carried out in the field of medicine. Medicine is a science, which has used methods from the area of risk analysis for a long time. The different papers will be used to discuss risk analysis as a tool in decision-making.</p> / QC 20100616

<p>Syftet med undersökningen är att kartlägga vilken kompetens en grupp pedagoger har inom matematikområdet och vilken kompetensutveckling de frågar efter, samt att se hur matematikutveckling kan få betydelse för de yngre barnens intresse och lärande av matematik.</p><p>Vi har använt oss av kvalitativa intervjuer med sammanlagt 10 pedagoger i förskola, förskoleklass och skolår 1.</p><p>I undersökningen framkommer att de pedagoger som fått kompetensutveckling efterfrågar mer, men också att de inte får tillräckligt med tid till att förmedla kunskapen till sina kollegor. Pedagogerna visar stor medvetenhet om sitt uppdrag från läroplanerna och vikten av att lägga en matematisk grund hos barnen. Resultatet visar på en ökad medvetenhet och kunskap hos dem som fått kompetensutveckling inom matematik i de flesta kategorier vi presenterar. Vår tolkning är att detta kan vara en effekt av den kompetensutveckling, det så kallade matematikpilotprojektet och matematiknätverk, som en del pedagoger genomgått i X kommun. Det märks däremot inte någon tydlig skillnad när det gäller att ta tillvara på matematiken i vardagen. Enligt vår undersökning är pedagogerna medvetna om matematiken i vardagen, men inte dess betydelse för att väcka barnens intresse för matematik.</p>

Detta examensarbete på C-nivå behandlar design av en snöskoter. Uppdragsgivaren är företaget SnoWolverine som vill utveckla en snöskoter med tre drivband varav två placerade i fronten. Den omfattande informationsinsamling som har skett under arbetets gång har visat att en trebandad skoter, som har utmärkt framkomlighet, har en stor marknad. De lösningar som finns på marknaden, främst fyrhjuling med bandsats, har alla kompromisser. Produktutvecklingsverktyg som funktionsanalys och QFD har använts i processen. Stort fokus har legat på utveckling av formspråket för snöskoter och utvecklingen av smarta funktioner som efterfrågas av målgruppen. Resultatet är en kraftfull snöskoter med ett kompakt utseende. Främre boggin är gjord så utrymmessparande som möjligt och designad för att vara robust. Unika funktioner är bland annat en vindtunnel som fungerar som vindruta, frontbåge med vinschfäste, utfällbar sadel och förvaringslösningar.

Examensarbetet är utfört i samarbete med företaget Mil Tech i Västerås. Arbetet har gått ut på att konvertera en redan existerande turbojetmotor med dragkraft på 110 Newton till en turboaxelmotor där effekten tas ut via en axel. Konverteringen av turbojetmotorn till en turboaxelmotor sker genom att konstruera en modul bestående av ett friturbinsteg som fästes på turbojetmotorn. Arbetets fokus har legat på att få en lättillverkad och enkel moduluppbyggt friturbinsteg som med få medel kan fästas direkt på turbojetmotorns utloppsdel utan att behöva modifiera turbojetmotorn. Det moduluppbyggda friturbinsteget innehåller alla de mekaniska detaljer som gör en konvertering från turbojetdrift till turboaxeldrift möjlig. Arbetet har inletts med att ta fram termodynamiska beräkningar för att avgöra motorns prestanda och motorns fysikaliska krav på design, konstruktion, material och hållfasthet. Examensarbetet innehåller solidmodeller samt konstruktionsritningar som gör det möjligt att utifrån detta bygga en fungerande friturbinmodul.

No description available.

Denna uppsats behandlar synen på kultur inom utvecklingsprojektet tusenet. Tusenet är ett projekt mellan Sverige och Turkiet och en del av Turkietprogrammet, som syftar till att underlätta och främja Turkiets medlemskap i EU samt att fördjupa de svensk-turkiska relationerna. Då denna uppsats bygger på kvalitativa intervjuer vill vi skapa förståelse snarare än att komma fram till några absoluta sanningar. Studien är baserad på sex stycken kvalitativa intervjuer med representanter från de svenska deltagarna i tusenet. Även en mindre omfattande telefonintervju för att utreda projektnamnet har utförts. Syftet med denna uppsats är att studera de medverkande aktörernas uppfattningar angående bilder av Turkiet, andra kulturer och utveckling. Syftet är även att kartlägga de medverkandes inställningar, och försöka utreda om det finns faktiska (eller endast inbillade) skillnader mellan turkar och svenskar.