Planning algorithms have applications in many fields such as robotics, logistics, and more.Planning for terrain following flights can be to utilize features of the terrain to minimizethe risk of detection. The similar problem of terrain avoidance is applicable to planningthe movement for survey or search vehicles, where low and fixed altitude may be important.Common problems that arise when planning for terrain following flights is that the dynamics ofthe vehicle are difficult to model, the state space is only represented in an approximate mannerand detailed calculations of the subject are computationally expensive. This work presents aplanning algorithm for the vertical component of terrain following flight paths using methods ofenergy, where the path itself is modelled as an elastic band deformed by virtual forces to followthe terrain. Using linear internal equations of motion for the elastic band, the computationalcomplexity can be kept low. Similar ideas have been used for planning algorithms in otherworks, but novel to the method presented here is that complicated limitations to the dynamicsof the vehicle can be treated in an effective manner. This is achieved by an adaptive linearcombination of different models for the internal elastic forces.

Kinetic Monte Carlo(KMC) algorithm are used to simulate the evolution of Au cluster on the Au substrate . The morphology of the thin film and detailed diffusion mechanism can be demonstrated in this study. Molecular dynamics simulation (MD) is used to determine the energy barrier(activation energy) of an Au atom adsorbed on the clean surface of the substrate. Then, the thin cluster evolution process, surface reaction and surface diffusion of the Au atoms is modeled by KMC method. The morphologies of the clusters at different temperatures with different number of atoms are also investigated. The simulation results are compared with literature on experimental results to demonstrate the diffusion mechanism, which is difficultly observed in experiments. A three-dimensional KMC simulation model is used in this study. The results are compared with those from experiments in order to identity the reliability of this KMC model and to modify this model. Nudged Elastic band simulation is used to determine the adsorption energy barrier of an Au atom on a clean Au substrate surface. From the KMC result a surface diffusion of Au migration process is proposed. The effect of the substrate temperature, and the number of atoms duration on the morphology of the Au cluster is obtained. The simulation results show a pyramid structure is built and collapsed from the corner and edge atoms fellow suit and then the atoms of top layers do so as well. Then results indicate that it is possible to to produce nano-gold (metal)-pyramid from Au cluster s by 1, melting clusters in short period and then quenching them, or 2. Depositing Au atoms at lower temperature as well as 500 K with controlled rate.

Cette thèse aborde l'étude du vieillissement thermique du système Fe-Cr. Nous avons étudié le mécanisme de diffusion de la lacune dans le cadre de la théorie de la fonctionnelle de la densité (Density Functional Theory - DFT) et examiné la capacité d'un potentiel empirique de la classe EAM (Embedded Atom Method) à reproduire les résultats DFT. Nous avons montré que l'énergie de migration de la lacune dépend fortement de l'environnement atomique du point de col où les interactions chrome-chrome et chrome-lacune déterminent en partie l’énergie de point de col. Nous avons proposé trois approches pour la paramétrisation d'un modèle Monte Carlo Cinétique (MCC) atomique : l’une entièrement basée sur le potentiel EAM, les autres partiellement basées sur nos calculs DFT. Les simulations par MCC du vieillissement thermique des alliages Fe-20% at. Cr et Fe-25% at. Cr à 773 K montrent la formation de précipités riches en chrome dont la croissance avec le temps suit une loi de puissance avec un exposant 1/3, en accord avec la théorie de Lifshitz-Slyozov-Wagner. La paramétrisation des simulations par MCC entièrement basée sur le potentiel EAM prédit une taille moyenne des précipités supérieure à celle observée expérimentalement, alors que cette dernière est sous-estimée par les paramétrisations partiellement basées sur nos calculs DFT. Ce désaccord semble avoir une origine cinétique plutôt que thermodynamique. La composition de la phase riche en chrome varie au cours de la séparation de phase, indiquant ainsi que la démixtion se produit par nucléation non-classique ou par décomposition spinodale. Des précipités interconnectés sont plus susceptibles de se former dans le système Fe-25% at. Cr plutôt que dans l’alliage Fe-20% at. Cr suggérant ainsi que, lorsque la concentration en soluté augmente, le mécanisme de démixtion se rapproche de la décomposition spinodale. / In this thesis, we address the study of the microstrucutre evolution of the Fe-Cr system under thermal ageing. The vacancy diffusion mechanism was investigated in the framework of the density functional theory (DFT) and the capability of a recently developed embedded atom method (EAM) empirical cohesive model to reproduce the DFT results was examined. We have shown that the vacancy migration energy strongly depends on the saddle point atomic environment where the chromium-chromium and the chromium-vacancy interactions partially determine the saddle point energy. We proposed three approaches for the parameterisation of an atomistic kinetic Monte Carlo (AKMC) model: one fully based on the EAM potential, the others partially based on our DFT calculations. The AKMC simulations of the thermal ageing of the Fe-20 at.%Cr and Fe-25 at.%Cr alloys at 773 K show the formation of chromium-rich precipitates whose growth with time follows a power law with exponent 1/3. This is consistent with the Lifshitz-Slyozov-Wagner theory of coarsening. The AKMC parameterisation fully based on the EAM potential predicts a mean precipitate size higher than the experimentally observed one, whereas the parameterisations partially based on our DFT calculations underestimate it. This disagreement seems to have a kinetic rather than thermodynamic origin. The composition of the precipitating phase varies during the phase separation thus indicating that the unmixing is driven by either a non-classical nucleation or a spinodal decomposition. Interconnected precipitates are more likely to form in the Fe-25 at.%Cr alloy than in the Fe-20 at.%Cr thus suggesting that, as the solute concentration increases, the spinodal decomposition is more likely to occur.

Under senare år har vi med hjälp av robotar som använder rörelseplanering kunnat automatisera olika processer och uppgifter. Idag finns det väldigt få strategier för lokal rörelseplanering vid jämförelse med global rörelseplanering. Syftet med det här projektet har varit att analysera tre strategier för lokal rörelseplanering, dessa har varit Dynamic Window Approach (DWA), Elastic Band (Eband) och Timed Elastic Band (TEB).I projektet har styrkor, svagheter, beteenden och förbättringsmöjligheter för respektive strategi studerats närmare genom att utföra olika simulerade tester. I testerna mätes tid för att nå mål, antal kollisioner och antalet gånger som målet nåddes. Under projektet användes en virtuell allriktad robot från ABB för att testa strategierna. Testerna genomfördes på ett så rättvist sätt som möjligt, där alla strategier fick samma antal försök och hade samma information om robotens begränsningar.Resultatet visar att TEB är den snabbaste strategin, följt av DWA och sista Eband som var den långsammaste strategin. TEB var också den strategi som presterade bäst vid dynamiska hinder, däremot var den också den strategi som kolliderade mest i testerna, medan Eband kolliderade minst. / In recent years, we have been able to automate various processes and tasks with the help of robots that use motion planning. Today, there are very few strategies for local motion planning when compared to global motion planning. The purpose of this project has been to analyze three strategies for local motion planning, these have been Dynamic Window Approach (DWA), Elastic Band (Eband) and Timed Elastic Band (TEB).In the project, strengths, weaknesses, behaviours and opportunities for improvement for each strategy have been studied in more detail by performing various simulated tests. The tests measure time to reach the goal, the number of collisions and the number of succeeding attempts. During the project, a virtual omni-directional robot from ABB was used to perform the tests. The tests were performed in as fair a way as possible, where all strategies got the same number of attempts and had the same information about the robot's limitations.The results show that TEB is the fastest strategy, followed by DWA and last Eband that was the slowest strategy. TEB was also the strategy that performed best in dynamic obstacles, however, it was also the strategy that collided most of the tests, while Eband collided the least.

With advancements in computer technology and processing power, the ability to examine chemical systems using theory continues to be more practicable. Using ab initio methods, such as density functional theory, we are now able to routinely simulate hundreds of atoms. This system size allows us to directly simulate surfaces and nano-materials that are industrially relevant. With the expansion of accessible systems comes the opportunity to develop new computational methods to extract their chemical properties. Of particular interest is bridging the time scale gap between simulation and experiment. The evolution of a system chemical in time can be directly simulated using classical dynamics, however, molecules vibrate on the order of femtoseconds and interesting transitions tend to happen on much longer time scales: milliseconds to seconds. In condensed phase chemical systems these interesting transitions are hindered by energy barriers so state to state dynamics are dominated by rare evens. Luckily, rare event transitions tend to happen through mountain passes in the potential energy landscape. Within harmonic transition state theory, the transition states between minima can be characterized by saddle points. Finding saddle points is a challenging problem which has not been satisfactorily solved; nevertheless, there are algorithms currently being used despite their deficiency. In particular, my work strives to improve the efficiency and stability of the nudged elastic band method and compare its performance to similar algorithms on a variety of test systems. In addition, I present a method to predict how energy-based chemical properties change with respect to the chemical composition of the system. This is achieved by taking a derivative of the property with respect to the atomic numbers of the atoms present in the system. The accuracy and predictive quality of these derivatives are assessed for both model and industrially relevant systems. With this information, we can follow these derivatives to optimize a desired property in the space of chemical composition. This method is a step toward using theory to rationally design compounds with desirable properties. / text

Irradiation induces a high concentration of defects in the structural materials of nuclear reactors, which are typically of body-centered cubic Iron (BCC Fe) and its alloys. The primary effect of irradiation is hardening which is caused by the blocking of dislocations with defects and defect clusters like point defects, self-interstitial loops, and voids. The dislocation-defect interactions are atomistic in nature due to the very small length and time scales involved, i.e., of the order of nanometers and picoseconds. To predict the effect of dislocation-defect interactions on the macroscopic mechanical and plastic behavior of the material, it is critically important to develop robust coupling schemes by which accurate atomic level physics of the rate-limiting kinetic processes can be informed into a coarse-grained model such as crystal plasticity. In this thesis we will develop an atomistically informed constitutive model. Relevant atomistic processes are identified from molecular dynamics simulations. The respective unit process studies are conducted using atomistic reaction pathway sampling methods like Nudged Elastic Band method. Stress-dependent activation energies and activation volumes are computed for various rate-liming unit processes like thermally activated dislocation motion via kinkpair nucleation, dislocation pinning due to self interstitial atom, etc. Constitutive laws are developed based on transition state theory, that informs the atomistically determined activation parameters into a coarse-grained crystal plasticity model. The macroscopic deformation behavior predicted by the crystal plasticity model is validated with experimental results and the characteristic features explained in the light of atomistic knowledge of the constituting kinetics. We also investigate on unique irradiation induced defects such as stacking fault tetrahedra, that are formed under non-irradiated condition. This thesis also includes our work on materials with internal interfaces that can resist irradiation induced damage. Overall, the research presented in this thesis involves the implementation and development of novel computational paradigm that encompasses computational approaches of various length and time scales towards robust predictions of the mechanical behavior of irradiated materials.

The minimum energy paths and transition states for the first two pyrolysis reactions of the tannin building blocks gallic acid and (+)-catechin were calculated by combining density functional theory with the climbing-image nudged elastic band method. For both investigated, the combined pyrolysis reaction was found to be endothermic across the full investigated temperature range and exergonic for temperatures of 1000 K and above when evaluated with the quantum chemical 'gold standard' approach CCSD(T). In the case of gallic acid, the dehydrogenation of pyrogallol was identified as the rate-determining pyrolysis step, whereas the catechol split-off was determined to be the rate-determining step of (+)-catechin pyrolysis. Additionally, simulated Raman spectra were able to explain the presence of subtle shoulder peaks in the spectrum of the binder Carbores®P. Another series of spectra assisted the identification of an ellagic acid pyrolysis product.

Made available in DSpace on 2014-06-11T19:22:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-10Bitstream added on 2014-06-13T18:49:42Z : No. of bitstreams: 1 fosco_lc_me_prud.pdf: 905074 bytes, checksum: 4682160d9d51bca48d98f5cdd23c2d6d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A inflamação sistêmica é um fator relevante na disfunção dos músculos esqueléticos de indivíduos com doença pulmonar obstrutiva crônica (DPOC). Esta disfunção pode ser revertida parcialmente por meio de treinamento físico que, contudo, provoca respostas imunes dependentes de vários fatores, entre eles, o tipo, a intensidade e a duração do exercício. Objetivo: avaliar respostas inflamatórias, bem como níveis de força muscular e valores de massa magra em pacientes com DPOC sem tratamento prévio, comparando dois protocolos de treinamento resistido. Casuística e métodos: 24 indivíduos com diagnóstico de DPOC confirmado por espirometria foram alocados em dois grupos: 12 indivíduos realizaram um treino resistido tradicional (RT) e 12 indivíduos, treino resistido com cordas elásticas (RE). A frequencia do treinamento foi de três vezes por semana, com duração de oito semanas consecutivas. Para a quantificação dos níveis plasmáticos do Fator de Necrose Tumoral alfa (TNF-α), Interleucina 1β (IL-1β) e Interleucina 10 (IL-10)... / Systemic inflammation is an important factor in skeletal muscle dysfunction in patients with chronic obstructive pulmonary disease (COPD). This dysfunction can be reversed partially by means of physical training, however, that causes immune responses depend on various factors including the type, intensity and duration of exercise. Objective: Objective: To evaluate the inflammatory responses, as well as levels of muscle strength and fat-free mass values in COPD patients without prior treatment, comparing two protocols of resistance training. Casuistic and methods: 24 subjects with a diagnosis of COPD confirmed by spirometry were divided into two groups: 12 patients underwent conventional resistance training (RT) and 12 subjects, resistance training with elastic bands (RE); the training was executed three times a week during eight consecutive weeks. For the quantification of plasma levels of tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β) and interleukin 10 (IL-10) ... (Complete abstract click electronic access below)

Title: Evaluation of training effect with elements of proprioceptive neuromuscular facilitation on shooting velocity by female handball players of the 1st league in the Czech Republic Objectives: The aim of this study is to determine, whether completing an exercise program based on elements of proprioceptive neuromuscular facilitation and using elastic band resistance can influence shooting velocity by female handball players. Methods: In this randomized control study 25 female handball players, who are playing the 1st league in Havlíčkův Brod, were divided into experimental (n = 13) and control group (n = 12). Both groups underwent an initial shooting velocity measurement (PRE) using radar gun Stalker Pro II. Then experimental group completed 6-week exercise program, based on D2 flexion and extension from proprioceptive neuromuscular facilitation against elastic band resistance. The control group did not perform any exercise like that. Both groups otherwise completed the same training program during the preparatory phase. After that the shooting velocity was again measured (POST). The results were statistically processed in the Jamovi using two-way repeated measures ANOVA. Results: There was a statistically significant improvement in shooting velocity of the control and experimental groups in the...

High temperature hydrogen attack (HTHA) is a damage mechanism that only affects carbon steel and low alloy material. Most of the data regarding HTHA are experimental-driven. Even though this approach has been successful, there are still much more things that the oil and gas industry does not understand about HTHA. The regions that were considered safe (below the Nelson curves) have experienced catastrophic failure. Our research consists of performing Molecular Dynamics (MD) and the Nudge Elastic Band (NEB) calculation of HTHA to better understand the atomistic behavior of this damage mechanism.