Hybrid approaches for mobile robot navigation

The work described in this thesis contributes to the efficient solution of mobile robot navigation problems. A series of new evolutionary approaches is presented. Two novel evolutionary planners have been developed that reduce the computational overhead in generating plans of mobile robot movements. In comparison with the best-performing evolutionary scheme reported in the literature, the first of the planners significantly reduces the plan calculation time in static environments. The second planner was able to generate avoidance strategies in response to unexpected events arising from the presence of moving obstacles. To overcome limitations in responsiveness and the unrealistic assumptions regarding a priori knowledge that are inherent in planner-based and a vigation systems, subsequent work concentrated on hybrid approaches. These included a reactive component to identify rapidly and autonomously environmental features that were represented by a small number of critical waypoints. Not only is memory usage dramatically reduced by such a simplified representation, but also the calculation time to determine new plans is significantly reduced. Further significant enhancements of this work were firstly, dynamic avoidance to limit the likelihood of potential collisions with moving obstacles and secondly, exploration to identify statistically the dynamic characteristics of the environment. Finally, by retaining more extensive environmental knowledge gained during previous navigation activities, the capability of the hybrid navigation system was enhanced to allow planning to be performed for any start point and goal point

GIS-based landform classification of Bronze Age archaeological sites on Crete Island

Various physical attributes of the Earth's surface are factors that influence local topography and indirectly influence human behaviour in terms of habitation locations. The determination of geomorphological setting plays an important role in archaeological landscape research. Several landform types can be distinguished by characteristic geomorphic attributes that portray the landscape surrounding a settlement and influence its ability to sustain a population. Geomorphometric landform information, derived from digital elevation models (DEMs), such as the ASTER Global DEM, can provide useful insights into the processes shaping landscapes. This work examines the influence of landform classification on the settlement locations of Bronze Age (Minoan) Crete, focusing on the districts of Phaistos, Kavousi and Vrokastro. The landform classification was based on the topographic position index (TPI) and deviation from mean elevation (DEV) analysis to highlight slope steepness of various landform classes, characterizing the surrounding landscape environment of the settlements locations. The outcomes indicate no interrelationship between the settlement locations and topography during the Early Minoan period, but a significant interrelationship exists during the later Minoan periods with the presence of more organised societies. The landform classification can provide insights into factors favouring human habitation and can contribute to archaeological predictive modelling

Tolerance on sphere radius for the calibration of the transfer function of coherence scanning interferometry

Although coherence scanning interferometry (CSI) commonly achieves a sub-nanometre noise level in surface topography measurement, the absolute accuracy is difficult to determine when measuring a surface that contains varying local slope angles and curvatures. Recent research has shown that it is possible to use a single sphere with a radius much greater than the source wavelength to calibrate the three-dimensional transfer function of a CSI system. A major requirement is the accurate knowledge of the sphere radius, but the three-dimensional measurement of a sphere with nanometre level uncertainty is a highly challenging metrology problem, and is not currently feasible. Perfect spheres do not exist and every measurement has uncertainty. Without having a quantitative understanding of the tolerance of the sphere radius, the calibration method cannot be used confidently for calibration of the transfer function of a CSI system that may be used in research laboratories or industry. In this paper, the effects of the tolerance of the radius of the calibration sphere on surface topography measurements are quantitatively analysed through a computational approach. CSI measurements of spherical, sinusoidal and rough surfaces are investigated in the presence of various degrees of radius error. A lookup table that relates the surface height error as a function of the radius error and surface slope angle is provided. The users may estimate the required tolerances of the sphere radius for their specific surface measurements if this calibration approach is used. The output of this paper provides a feasibility analysis for this calibration method for further development and applications

Newton-Cartan Gravity and Torsion

We compare the gauging of the Bargmann algebra, for the case of arbitrary torsion, with the result that one obtains from a null-reduction of General Relativity. Whereas the two procedures lead to the same result for Newton-Cartan geometry with arbitrary torsion, the null-reduction of the Einstein equations necessarily leads to Newton-Cartan gravity with zero torsion. We show, for three space-time dimensions, how Newton-Cartan gravity with arbitrary torsion can be obtained by starting from a Schroedinger field theory with dynamical exponent z=2 for a complex compensating scalar and next coupling this field theory to a z=2 Schroedinger geometry with arbitrary torsion. The latter theory can be obtained from either a gauging of the Schroedinger algebra, for arbitrary torsion, or from a null-reduction of conformal gravity.Comment: 21 page

Raw data for the article "Combining STPA and BDD for Safety Analysis and Verification in Agile Development: A Controlled Experiment"

<p>These files include the raw data of pre-questionnaire, operation report, post-questionnaire and hypothesis testing in the experiment. </p

Evolution of cooperation from a random initial state with limited resource.

<p>The snapshots are taken at MCS = 0 (a), 1 (b), 8 (c) and 1024 (d). The system size <i>L</i> = 100 and <i>b</i> = 1.1, <i>c</i> = 1.01.</p

The cooperation on square lattice with limited resource.

<p>(a) The number of dead individuals on the <i>c</i> − <i>b</i> parameter plane. (b) The average characteristic parameter on the <i>c</i> − <i>b</i> parameter plane. (c) The standard deviation of <i>CP</i> on the <i>c</i> − <i>b</i> parameter plane. (d) The average characteristic parameter on the <i>c</i> − <i>b</i> parameter plane in a small parameters region(1.0 < <i>c</i> < 1.4,1.0 < <i>b</i> < 1.4). Each data point is an average of 100 independent realizations.</p

Tuning Multistep Biocatalysis through Enzyme and Cofactor Colocalization in Charged Porous Protein Macromolecular Frameworks

Spatial organization of biocatalytic activities is crucial to organisms to efficiently process complex metabolism. Inspired by this mechanism, artificial scaffold structures are designed to harbor functionally coupled biocatalysts, resulting in acellular materials that can complete multistep reactions at high efficiency and low cost. Substrate channeling is an approach for efficiency enhancement of multistep reactions, but fast diffusion of small molecule intermediates poses a major challenge to achieve channeling in vitro. Here, we explore how multistep biocatalysis is affected, and can be modulated, by cofactor–enzyme colocalization within a synthetic bioinspired material. In this material, a heterogeneous protein macromolecular framework (PMF) acts as a porous host matrix for colocalization of two coupled enzymes and their small molecule cofactor, nicotinamide adenine dinucleotide (NAD). After formation of the PMF from a higher order assembly of P22 virus-like particles (VLPs), the enzymes were partitioned into the PMF by covalent attachment and presentation on the VLP exterior. Using a collective property of the PMF (i.e., high density of negative charges in the PMF), NAD molecules were partitioned into the framework via electrostatic interactions after being conjugated to a polycationic species. This effectively controlled the localization and diffusion of NAD, resulting in substrate channeling between the enzymes. Changing ionic strength modulates the PMF–NAD interactions, tuning two properties that impact the multistep efficiency oppositely in response to ionic strength: cofactor partitioning (colocalization with the enzymes) and cofactor mobility (translocation between the enzymes). Within the range tested, we observed a maximum of 5-fold increase or 75% decrease in multistep efficiency as compared to free enzymes in solution, which suggest both the colocalization and the mobility are critical for the multistep efficiency. This work demonstrates utility of collective behaviors, exhibited by hierarchical bioassemblies, in the construction of functional materials for enzyme cascades, which possess properties such as tunable multistep biocatalysis

Human treadmill walking position data, 3 markers

Compressed file contains text files with human walking position data for 3 markers, 10 subjects, 3 trials. See readme.txt and original article for more details

Supplemental Material, eitc_children_appendixtables_PFR_final_(1) - Effects of Higher EITC Payments on Children’s Health, Quality of Home Environment, and Noncognitive Skills

<p>Supplemental Material, eitc_children_appendixtables_PFR_final_(1) for Effects of Higher EITC Payments on Children’s Health, Quality of Home Environment, and Noncognitive Skills by Susan Averett, and Yang Wang in Public Finance Review</p