Die vorliegende Arbeit befasst sich mit dem Versuch der Optimierung von Simulated Annealing. Genauer gesagt, werden Simulationsergebnisse für einfache Spinglassysteme in Abhängigkeit von verschiedenen Nachbarschaftsmodellen berechnet – jeweils unter Verwendung des optimalen Abkühlverlaufs. Ziel ist es, eine Faustregel für die dynamische Anpassung der Nachbarschaftsbeziehung während einer Annealing-Simulation zu finden. / The thesis at hand presents an attempt to optimize simulated annealing. In particular, annealing results are computed based on different move class definitions for Ising spin systems while simultaneously applying an existing algorithm to determine the optimal temperature schedule for each case. The aim is to find a rule of thumb for dynamic adjustment of the move class during an annealing run.

Silicon carbide (SiC), is a wide band gap (2.4 eV < Eg < 3.3 eV) semiconducting material well known for its potential applications in high-temperature, high-power, high-frequency or hard radiation resistant devices. In this thesis, we are broadening elementary knowledge about this material. We identify energy levels in the material, using Photo-Hall effect spectroscopy supported by the temperature dependency of classic Hall effect measurement and temperature dependent photoluminescence. This knowledge is essential to allow SiC application as a radiation detector.

2D semiconductors are one of the most promising materials for next-generation electronics. Realizing continuous 2D monolayer semiconductors with single-crystalline structure at the wafer scale is still a challenge. We developed an epitaxial phase conversion (EPC) process to meet these requirements. The EPC process is a two-step process, where the sulfurization process was carried out on pre-deposited Mo-containing films. Traditionally, two-step processes for 2D MoS2 and other chalcogenides have suffered low-quality film and non-discontinuity at monolayer thickness. The reason was regarded as the low lattice quality of precursor film. The EPC process solves these problems by carefully preparing the precursor film and carefully controlling the sulfurization process. The precursor film in the EPC process is epitaxial MoO2 grown on 2″ diameter sapphire substrate by pulsed laser deposition. This epitaxial precursor contains significantly fewer defects compared to amorphous precursor films. Thus fewer defects are inherited by the EPC MoS2 film. Therefore, EPC MoS2 film quality is much better. The EPC prepared monolayer MoS2 devices to show field-effect mobility between 10 ~ 30 cm2·V-1s-1, which is the best among the two-step process. We also developed a CLAP method further to reduce the defects in the precursor oxide film; thus, in-plane texture in the thicker MoS2 film was eliminated, and a single-crystalline structure was obtained in the wafer-scale MoS2 films. The potentially feasible technique to further improve the 2D film quality is pointed out for our next research plan. Meanwhile, the epitaxial phase conversion process was proposed to be as a universal growth method. Last but not least, we demonstrate several potential applications of the wafer-scale single-crystalline MoS2 film we developed, such as logic circuits, flexible electronics, and seeding layer of van der Waal or remote epitaxial growth.

Procedural level generation is a novel area of research within the field of computer graphics and game development. However, current research and implementations of procedural generation for cooperative games is sparse. Further study is required to validate the use of automatic level creation and to test additional methods of optimization for cooperative games. Additionally, despite many recent developments, many areas within the field of virtual reality remain underexplored. We propose a mathematically defined total cost function for controlling a procedural level generation algorithm for cooperative virtual reality games. This cost term controls an algorithm which gradually improves a generated solution over a series of iterations, bringing it to an optimal state. We present here two games with procedurally created levels and gameplay elements using this mathematical total cost function, as well as proposed experiments to validate the effectiveness of this content in encouraging cooperation and potential use cases for this technology.

Stainless steel family grades are very famous for their combined corrosion resistance and high mechanical properties. These properties can be improved further by decreasing the content of impurities like carbon and oxygen. The main purpose of this research work is to study the possibility of stainless steel powder decarburization by vacuum annealing. The influence of different process parameters like treatment time, temperature, fraction size and depth of the powder layer on the decarburization process was analyzed. The investigation results showed that it is possible to achieve extra low values of carbon and oxygen in steel powder by processing it with optimum process parameters.

Thesis: B.S., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 1980 / Includes bibliographical references. / by Evan Joseph Hammerman. / B.S. / B.S. Massachusetts Institute of Technology, Department of Materials Science and Engineering

The university timetabling problem is an NP-complete problem which schools all over the world face every semester. The aim of the problem is to schedule sets of events such as lectures and seminars into certain time slots without violating numerous specified constraints. This study aimed to automate this process with the help of simulated annealing and compare the results with a genetic algorithm. The input data sets were inspired by the Royal Institute of Technology in Stockholm. The results showed a great run time difference between the two algorithms where the simulated annealing performed much better. They also showed that even though the simulated annealing algorithm was better during all stages, the genetic algorithm had a much better performance in early stages than it had in latter. This led to the conclusion that a more optimized, hybrid algorithm could be created from the two algorithms provided that the genetic algorithm could benefit from the improvements suggested in previous research. / Universitetsschemaläggningsproblemet är ett NP-fullständigt problem som skolor över hela världen måste hantera innan varje termin. Syftet med problemet är att schemalägga händelser, såsom föreläsningar och seminarier, utan att bryta flertalet fördefinierade villkor. Denna studie hade som mål att automatisera denna process med hjälp av algoritmkonstuktionsmetoden simulerad glödgning och sedan jämföra resultatet med en genetisk algoritm. De datamängder som användes är inspirerade av den verkliga situationen på KTH. Resultaten visar stora tidsmässiga skillnader där algoritmen baserad på simulerad glödgning går snabbare. De visar dock också att den genetiska algoritmen har en bättre prestanda i tidigare stadier än i senare. Detta ledde till slutsatsen att en mer optimerad hybridalgoritm kan skapas av de två algoritmerna, förutsatt att den genetiska algoritmen kan dra nytta av förbättringar som föreslagits i tidigare forskning.

A growing world population means an increase in crop demand. At the same time climate change threatens food security as crops may become maladapted to a new environment. We need to adapt crops to increase crop yield and become resistant to a changed environment to meet this. Crop wild relatives (CWR), which have a genetic relatedness with our crops, will be of importance as a genetic resource for crop adaption and needs to be protected. Vaccinium myrtillus is one of the prioritized species on the Nordic countries CWR priority list. Here I report PCR protocols that can be used for amplifying microsatellites, or SSRs, within V. myrtillus for use in analyses of genetic diversity within and between populations. PCRs with varying annealing temperatures (Ta) were performed. An optimal Ta for the primer pair was found for four SSR loci, and for four SSR loci, an approved Ta was found. These eight primer pairs can be used to amplify SSRs for analyses of the genetic diversity between V. myrtillus populations. This is needed to evaluate which populations to focus on in conservation programmes to ensure a broad genetic diversity usable in crop adaptation to meet increasing crop demand and climate change.

This dissertation is concerned with the unconstrained global optimization of nonlinear problems. These problems are not easy to solve because of the multiplicity of local and global minima. In this dissertation, we first study the pattern search method for local optimization. We study the pattern search method numerically and provide a modification to it. In particular, we design a new pattern search method for local optimization. The new pattern search improves the efficiency and reliability of the original pattern search method. We then designed two simulated annealing algorithms for global optimization based on the basic features of pattern search. The new methods are therefore hybrid. The first hybrid method is the hybrid of simulated annealing and pattern search. This method is denoted by MSA. The second hybrid method is a combination of MSA and the multi-level single linkage method. This method is denoted by SAPS. The performance of MSA and SAPS are reported through extensive experiments on 50 test problems. Results indicate that the new hybrids are efficient and reliable.

Quantum annealing represents an essential milestone towards the goal of adiabatic quantum computing. In quantum annealing, the computation involves finding the ground state of a classical Ising-like Hamiltonian realized as interactions between qubits. Quantum fluctuations are introduced to allow the wavefunction of the qubits to explore the energy landscape, the hope being that the wavefunction finds a minimum energy configuration and possibly giving the result of the computation. While quantum annealing likely may not be as powerful as adiabatic quantum computing, it is possible that it may be better at optimization compared to analogous classical algorithms. In physical realizations of quantum annealing, there are still questions as to the role of quantum fluctuations in the operation of a device given the short coherence times of the individual qubits. These questions have consistently posed a serious theoretical challenge making it difficult to verify experimental results. Here we simplify the problem by considering a system of qubits with ferromagnetic interactions, modeling the decoherence effects as classical noise in the transverse-field of each qubit. We compare the calculations to data collected from a system of manufactured qubits produced by D-wave Systems by performing a finite-size scaling analysis that captures the competition between quantum fluctuations of the transverse-field and bit-flip errors from the noise. We argue that on time-scales larger than the single-qubit decoherence time, the device produces the expected quantum fluctuations for the many-body system. Using this finite-size scaling, one can diagnose sources of noise in the system. Hopefully, in the near future, these devices will not only be realizing coherent quantum annealing but will likely be useful as another example of synthetic quantum matter.