Quantum annealing (QA) is an optimization process in quantum computing similar to the probabilistic metaheuristic simulated annealing (SA). The QA process involves encoding an optimization problem into an energy landscape, which it then traverses in search for the point of minimal energy representing the global optimal state. In this thesis two different implementations of QA are examined, one run on a binary quadratic model (BQM) and one on a discrete quadratic model (DQM). These are then compared to their traditional counterpart: SA, in terms of performance and accuracy when solving the graph coloring problem (GCP). Regarding performance, the results illustrate how SA outperforms both QA implementations. However, it is apparent that these slower execution times are mostly due to various overhead costs that appear because of limited hardware. When only looking at the quantum annealing part of the process, it is about a hundred times faster than the SA process. When it comes to accuracy, both the DQM-implementation of QA and SA provided results of high quality, whereas the BQM-implementation performed notably worse, both by often not finding the optimal values and by sometimes returning invalid results. / Quantum annealing (QA) är en kvantbaserad optimeringsprocess som liknar den probabilistiska metaheuristiken simulated annealing (SA). QA går ut på att konvertera ett optimeringsproblem till ett energilandskap, som sedan navigeras för att hitta punkten med lägst energi, vilket då motsvarar den optimala lösningen på problemet. I denna uppsats undersöks två olika implementationer av QA: en som använder en binary quadratic model (BQM) och en som använder en discrete quadratic model (DQM). Dessa två implementationerna jämförs med deras traditionella motsvarighet: SA, utifrån både prestanda och korrekthet vid lösning av graffärgningsproblemet (GCP). När det gäller prestanda visar resultaten att SA är snabbare än båda QA implementationerna. Samtidigt är det tydligt att denna prestandaskillnad framförallt beror på diverse förberedelser innan exkueringen startar på kvantdatorn, vilka är krävande på grund av olika hårdvarubegränsningar. Om man endast betraktar kvantprocesserna visar vår studie att QA implementationerna är ungefär hundra gånger snabbare än SA. Gällande korrekthet gav både DQM-implementationen av QA och SA resultat av hög kvalitet medan BQM-implementationen presterade betydligt sämre. Den gjorde detta dels genom att inte skapa optimala resultat och genom att returnera otillåtna lösningar.

No description available.

No description available.

No description available.

No description available.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

<p>Recrystallisation annealing, a repeated heat treatment between different stages of cold rolling of martensitic chromium steel strip, is successful when neither high rolling forces nor wear of the working rolls occur during the subsequent cold rolling. Mechanical properties as tensile strength, yield, elongation or hardness have been, by tradition, the criteria that described the quality of the annealing process. In recent years, the development of the measurement equipment in the rolling mills and of the instruments for material investigations has accentuated more and more the role played by the microstructural properties in the evaluation of the heat treatment. Two microstructural characteristics of the degree of annealing are, firstly and most important, the recrystallisation degree, and, secondly, the secondary carbide density.</p><p>The sample manufacturing and heat treatment, modelling and microstructure investigations by light optical- (LOM) and scanning electron microscopy (SEM) described in this article were carried out at Sandvik Materials Technology’s R&D Department and Bell Furnace Line in Sandviken, Sweden, while microstructure investigations and evaluation by scanning electron microscopy with field emission gun (FEG-SEM) and electron back scatter diffraction (EBSD) were done at the Corrosion and Metals Research Institute (KIMAB) in Stockholm, Sweden.</p><p>The first part of this work shows that, in contrast to the traditional methods LOM and SEM, that use chemical etching for the preparation of the samples, EBSD can successfully characterise recrystallised structures in annealed martensitic chromium steels. Unlike conventional microscopy with LOM and SEM, EBSD is able to reveal the grain geometry, as well as to separate and identify the different phases in this kind of steels (ferrite, M23-, M6-carbides). Important parameters such as grain size, particle size and recrystallised fraction can be measured with high accuracy. This information can be used to understand, evaluate, control and even predict the recrystallisation annealing of martensitic chromium steel.</p><p>The second part of this work presents how the results from microstructure description by EBSD can be directly used in relatively simple empirical models for determination of recrystallisation degree as function of the annealing parameters and the deformation history. EBSD was applied to evaluate the degree of recrystallisation in a series of annealing tests, with the purpose to model recrystallisation temperature in two types of martensitic chromium steel strip, a traditional one and one alloyed with molybdenum, cold rolled with different amounts of reduction and annealed with different temperatures, soaking times and heating rates. The empirical quadratic models were built with Umetrics’ software for experimental design, MODDEÒ 8.0 and they defined the recrystallisation degree (limits for LAGB and HAGB were set to 1.5° and 7.5° for the first grade and 2.5° and 10° for second one) and the secondary carbides density as functions of annealing temperature, soaking time and cold reduction (the factor heating rate was removed as nonsignificant). To be observed that these empirical models were fit much better for the recrystallisation degree than for the secondary carbides density.</p><p>The modelling work described above, together with the implementation of online physical temperature models in the bell annealers may lead to an increased productivity in the production plant by shortening the annealing cycle and minimising scrap and thus to an economical gain of ca 1,5 MSEK per year at Sandvik Materials Technology.</p><p> </p>

No description available.

No description available.

No description available.