We propose a novel 3D navigation system for autonomous vehicle path-planning. The system processes a point-cloud data from an rgb-d camera and creates a 3D occupancy grid with adaptable cell size. Occupied grid cells contain normal distribution characterizing the data measured in the area of the cell. The normal distributions are then used for cell classification, traversability and collision checking. The space of traversable cells is then used for path-planning. The ability to work in three-dimensional space allows the usage of autonomous robots in highly structured environments with multiple levels, uneven surface or various elevated and underground crossings. That is important for the usage of robots in real- world scenarios, in urban areas or for disaster rescue missions. Powered by TCPDF (www.tcpdf.org)

In this work we present the problem of multi-agent path-finding with dynamic obstacles, a generalisation of multi-agent path-finding (MAPF) in which the environment contains randomly-moving dynamic obstacles. This generalisation can be though of as an abstraction of incomplete knowledge of the environment or as a simplification of the multi-agent path-finding where we do not include all agents in the cooperative planner. We adapt three planning algorithms for MAPF to work in an environment with dy- namic obstacles: Local-Repair A* (LRA*), Windowed Hierarchical Cooper- ative A* (WHCA*) and Operator Decomposition with Independence Detec- tion (OD/ID). In addition, we propose two heuristics for these algorithms in dynamic environments: Path Rejoining and Obstacle Predictor. In our experiments, we find that LRA* and WHCA* are best suited for the dy- namic environment. The Path Rejoining heuristic is successful in improving run-times at a small cost in makespan. Obstacle Prediction is capable of lowering the number of times a plan has to be found, but the overhead of our implementation outweighs any performance benefits in most cases. 1

This dissertation deals with the rise of new industries through entrepreneurial activities. The aim is to investigate how differences in contexts might encourage or discourage entrepreneurial activities. This contextualization of entrepreneurship enhanced our understanding of when, how and why entrepreneurial activities happen. Entrepreneurship is recognized to be a spatially uneven process and, in addition to previous research that has examined the actions of individual entrepreneurs, we also need to understand the context in which entrepreneurship occurs. We have a good understanding of how structural conditions like industry structure, organization structure and agglomeration effects influence the context, but we know little about how the social dimension of the context is the transmitting medium between structural conditions for entrepreneurship and the decision to act upon identified entrepreneurial opportunities. Following this line of argument, this dissertation is built on the assumption that entrepreneurship is a social phenomenon which gives strong arguments for including local culture in entrepreneurship research. The temporal persistence and the pronounced differences of culture and structural conditions between places reflect path-dependent processes. I therefore use regional path dependence as an interpretative lens to study the contextualization of entrepreneurship in two Swedish cities. Although each context is unique, some generalizations can be drawn from the four individual papers in this dissertation. The first is that industrial legacy leads to the formation of a distinct local culture and that the persistency of this culture influences the subsequent entrepreneurial activities in new local industries. The second is that this persistency of culture suggests that entrepreneurs who are outsiders, geographically or socially, are the driving forces for the emergence of new local industries. Finally, new industry emergence is a result of a combination of exogenous forces and initial local conditions, but it is the entrepreneurial individuals who translate these forces and conditions into entrepreneurial activities.

INTRODUCTION: Smoking is the leading cause of preventable death in the United States and has been shown to be harmful to human health. Among alternative tobacco products, e-cigarettes have been widely regarded as the safest substitute to the traditional cigarette. However, debate remains about their safety and possible ill effects. AIM: The purpose of this study was to assess characteristics associated with e-cigarette use (everyday/some days/no use) and examine factors related to former smokers replacing a traditional smoking habit with e-cigarette use (yes/no). METHODS: A secondary data analysis was conducted with the Public Use Files (PUFs) for the Population Assessment of Tobacco and Health (PATH) Study, a nationally representative, longitudinal cohort study of tobacco use. Bivariate and multivariable unweighted and weighted generalized linear models were developed for value and comparative purposes, as well as multilevel models to account for within geographical region clustering. Ordinal logistic regression was used to analyze the ordinal e-cigarette use outcome, and logistic regression with the e-cigarette smoking status of former smokers outcome. RESULTS: Covariates associated with e-cigarette use included having rules that allowed smoking non-combustible tobacco inside the home (everyday vs no use: OR = 0.33, CI = 0.27-0.41; somedays vs no use: OR = 0.58, CI = 0.53-0.64), older than 35 years old (everyday vs no use: OR = 0.63, CI = 0.52-0.75; somedays vs no use: OR = 0.86, CI = 0.76-0.96), and positive or neutral self-opinion on tobacco (everyday vs no use: OR = 0.88, CI = 0.73-1.05; somedays vs no use: OR = 1.38, CI = 1.22-1.55). Factors related to e-cigarette use in former smokers included rules allowing non-combustible tobacco products inside the home (Weighted: OR = 0.19, CI = 0.15-0.24; Unweighted: OR = 0.15, CI = 0.12-0.19; Mixed: OR = 0.19, CI = 0.15-0.24), aged 18-35 years (Weighted: OR = 1.45, CI = 1.16-1.80; Unweighted: OR = 2.91, CI = 2.27-3.72; Mixed: OR = 1.45, CI = 1.16-1.80), and not having any health insurance (Weighted: OR = 0.57, CI = 0.44-0.75; Unweighted: OR = 0.47, CI = 0.34-0.64; Mixed: OR = 0.57, CI = 0.44-0.75). DISCUSSION: Family tolerance of smoking and one’s self-opinion on tobacco were factors found to be strongly associated with e-cigarette use. The prevalence of e-cigarette use among young adults raises concerns and necessitates a multi-disciplinary approach to monitor and intervene. Further study is needed to better understand e-cigarette smoking consumption behavior and effects.

Master of Science / Department of Mechanical and Nuclear Engineering / Dale E. Schinstock / The goal of this research is to develop methods and tools for generating flight plans for an unmanned aerial vehicle (UAV). A method of generating flight plans is needed to describe data collection missions, such as taking aerial photographs. The flight plans are two-dimensional and exist in a plane a fixed distance above the Earth. Since the flight areas are typically small, the Earth's curvature is not accounted for in flight plan generation. Designed to completely cover a specified field area, the plans consist of a series of line and arc segments and are described in a format that is recognized by the Piccolo autopilot used by the Kansas State University Autonomous Vehicle Systems (AVS) Lab. Grids are designed to cover the field area, and turn maneuvers are designed to ensure efficient flight plans. The flight plan generation process is broken into several parts. Once a field area is defined, path lines covering this area are calculated. Optimal turn maneuvers are calculated to smoothly connect the path lines in a continuous flight plan. Two methods of determining path line order are discussed. One method flies the lines in the order that they are arranged spatially; the other method decides line order by calculating the shortest turn maneuver to another path line. After the flight plan is generated, a text file is created in a format that is readable for the autopilot. In order to easily generate flight plans, a graphical user interface (GUI) has been created. This GUI allows a user to easily generate a flight plan without modifying any code. The flight plan generation software is used to build example flight plans for this thesis. These flight plans were flown with an UAV and test results are presented.

Industrial metal forming operations generally require several deformation steps in order to create the final product. The mechanical behavior of materials undergoing strain path changes can be very different from those deformed in a given direction to fracture. The work presented here employed laser drilled model materials to better understand the effect of pre-strains and strain path changes on void growth and linkage leading to fracture is studied. The experimental results show that increasing pre-strain results in faster void growth which was justified in terms work hardening rate in the sample. Scanning electron microscope images revealed that the ductility of the sample decreased with increasing pre-strain but only slightly compared to the large decrease in far field strain at failure. This suggests that pre-strain affects strain localization significantly and to a lesser extent the ductility. Finally a finite element model has been built to predict the linkage between voids.

Cold rolled aluminum is a widely used metal in industry. The forming limit diagram (FLD) which is commonly used to predict safe deformation parameters currently fails to predict the uniform elongation after non-proportional strain path often found in industrial operations. In this work, a non-proportional strain path change in aluminum alloy 3104 going from plane strain tension to uniaxial tension was investigated. Plane strain tensile tests have been carried out to various pre-strains (3%, 6% and 9%), followed by uniaxial tensile tests at various orientation with respect to the tensile direction (0°, 45° and 90°). Digital image correlation (DIC) was employed to analyze the strain distribution in the sample during deformation. The mechanical response was studied as a function of pre-strain and reloading angle to quantify the effect of strain path change on AA3104.

Pseudo-spectral optimal solvers are used to optimize numerically a performance index of a dynamical system with differential constraints. Although these solvers are commonly used for space vehicles and space launchers for trajectory optimization, few experimental papers exist on optimal control of small airships. The objective of this thesis is to evaluate the use of a pseudo-spectral optimal control solver for generating dynamically constrained, minimal time trajectories. A dynamical model of a small airship is presented, with its experimental virtual mass, drag and motor experimentally modeled. The problems are solved in PSOPT, a pseudo-spectral optimal control code. Experimental tests with a small scale model are performed to evaluate the generated paths. Although drift occurs, as a consequence of an open loop control, the vehicle is capable of following the path. This results of this thesis may find uses in verifying how close to optimal discreet path planners are, to plan complex trajectories on short distances, or to generate dynamic maneuverer such as take-off or landing. Ultimately, improving path planning of small airships will improve their safety, maneuverability and flight-time, which makes them fit for scientific monitoring, for search and rescue, or as mobile telecommunications platforms.

Stress corrosion cracking (SCC) of alloy 600 is regarded as one of the most important challenges to nuclear power plant operation worldwide. This study investigates two heats of alloy 600 (forged control rod drive mechanismnozzle and rolled divider plate) in order to obtain a better understanding of the effects of the material parameter on the SCC phenomenon. The experimental approach was designed to determine the effect of the manufacturing process (forged vs. rolled), the cold-work (as-received vs. cold-worked) and the strain path (monotonic vs. complex) on SCC of alloy 600. Specimens with different strain paths have been produced from two materials representative of plant components and tested in high temperature (360°C) high pressure primary water environment. The manufacturing process has been proven to have a great effect on the stress corrosion cracking behaviour of alloy 600. Indeed, the SCC susceptibility assessment has demonstrated that the rolled materialis resistant to SCC even after cold work, whereas the forged material is susceptible in the as-received state. Microstructural characterisations have been undertaken to explain these differences in SCC behaviour. The carbide distribution is the main microstructural parameter influencing SCC but the misorientation, in synergy with the carbide distribution, has been proven to give a better representation of the materials SCC susceptibilities.

Enzymes are immensely powerful and efficient heterogenous catalysts which are essential for life. As essential to life as enzymes are, it is still not well understood exactly how they enhance the rate of their catalyzed reactions up to 19 orders of magnitude over their solution phase counterpart reactions. Recent research has focused on sub--picosecond motions coupled to the reaction coordinate, called rate--promoting vibrations, which are important components of several well--known enzymatic mechanisms and build upon previous models of enzyme activity. Herein I present two studies which are expressly focused on providing tools and knowledge to understand how dynamics affects enzymatic reactions. First, I present a method for the calculation of kinetic isotope effects from first principles, using transition path sampling and centroid molecular dynamics. This method allows for the calculation of kinetic isotope effects without the assumptions necessitated by transition state theory or free energy perturbation methods. It was found that this method could calculate the primary H/D kinetic isotope effect of the conversion of benzyl alcohol to benzaldehyde in yeast alcohol dehydrogenase to within the margin of error of experimentally measured kinetic isotope effects of the same reaction. Second, I examined the role that evolution plays in the preservation of these rate--promoting vibrations, by performing a transition path sampling study of two lactate dehydrogenases, those of Plasmodium falciparum and Cryptosporidium parvum, which evolved through separate gene duplication events from a common malate dehydrogenase ancestor. It was found that though both lactate dehydrogenases share the same rate--promoting vibration, and indeed share the rate--promoting vibration found in other lactate dehydrogenases, the sequence variations in lactate dehydrogenase from P. falciparum causes a diminished contribution of the motions to the reaction coordinate. The studies presented in this dissertation contribute to the our understanding of enzymes on an atomistic level, as well as providing tools necessary for designing novel de novo enzymes and targeted drugs for enzymes of disease--causing organisms.