Adaptive and Collaborative Bathymetric Channel-Finding Approach for Multiple Autonomous Marine Vehicle

This paper reports an investigation into the problem of rapid identification of a channel that crosses a body of water using one or more Unmanned Surface Vehicles (USV). A new algorithm called Proposal Based Adaptive Channel Search (PBACS) is presented as a potential solution that improves upon current methods. The empirical performance of PBACS is compared to lawnmower surveying and to Markov decision process (MDP) planning with two state-of-the-art reward functions: Upper Confidence Bound (UCB) and Maximum Value Information (MVI). The performance of each method is evaluated through comparison of the time it takes to identify a continuous channel through an area, using one, two, three, or four USVs. The performance of each method is compared across ten simulated bathymetry scenarios and one field area, each with different channel layouts. The results from simulations and field trials indicate that on average multi-vehicle PBACS outperforms lawnmower, UCB, and MVI based methods, especially when at least three vehicles are used.Comment: (v1) Submitted to IEEE International Conference on Robotics and Automation (ICRA) 202

Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion

BACKGROUND: Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. METHODS: We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1) surface contact heating and (2) spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. RESULTS: The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. CONCLUSIONS: The heat transport system model of the skin was solved by exploiting the mathematical analogy between local thermal models and local electrical (charge transport) models, thereby allowing robust, circuit simulation software to obtain solutions to Kirchhoff's laws for the system model. Transport lattices allow systematic introduction of realistic geometry and spatially heterogeneous heat transport mechanisms. Local representations for both simple, passive functions and more complex local models can be easily and intuitively included into the system model of a tissue

Parameterization of a coarse-grained model of cholesterol with point-dipole electrostatics

© 2018, Springer Nature Switzerland AG. We present a new coarse-grained (CG) model of cholesterol (CHOL) for the electrostatic-based ELBA force field. A distinguishing feature of our CHOL model is that the electrostatics is modeled by an explicit point dipole which interacts through an ideal vacuum permittivity. The CHOL model parameters were optimized in a systematic fashion, reproducing the electrostatic and nonpolar partitioning free energies of CHOL in lipid/water mixtures predicted by full-detailed atomistic molecular dynamics simulations. The CHOL model has been validated by comparison to structural, dynamic and thermodynamic properties with experimental and atomistic simulation reference data. The simulation of binary DPPC/cholesterol mixtures covering the relevant biological content of CHOL in mammalian membranes is shown to correctly predict the main lipid behavior as observed experimentally

Promoting Interdisciplinary Integrated Design Education Through Mass Timber

14 pagesAn integrated design process ideally involves close coordination among the professionals designing architectural, structural, and mechanical systems, and with the construction team and manufacturers of building products; however, this process is not universally followed in practice, nor is it a common model for design education, either in architecture or in engineering. New developments in the United States in mass timber products present a unique opportunity to advance interdisciplinary integrated design processes both in practice and in schools. As architects and engineers explore this field, they are finding that in order to understand material possibilities and limitations and better manage project delivery schedules they need to work in integrated teams from the start, including close coordination with manufacturers, fabricators and construction professionals. Faculty in the University of Oregon (UO)’s Department of Architecture have modelled this integrated practice method in a series of design studios focused on mass timber systems in which student teams either work with architecture faculty and interdisciplinary consultants or with teams of structural engineering students and architecture and engineering faculty. To further this integrated practice model, an interdisciplinary MS degree in mass timber design is being developed by UO’s Architecture Department and Oregon State University (OSU)’s Department of Wood Science and Engineering for architecture, structural engineering and construction management students with a professional undergraduate degree. The students will be working on projects in interdisciplinary teams with interdisciplinary faculty teams, preparing the next generation of professionals to be well equipped for a future of integrated design practice

Adaptive Collaborative Channel Finding Approaches for Autonomous Marine Vehicles

This thesis presents an investigation into the problem of rapid identification of a channel that crosses a body of water, using one or more Autonomous Marine Vehicles (AMVs). A new algorithm called Proposal Based Adaptive Channel Search (PBACS) is presented as a potential solution that improves upon current methods. The empirical performance of PBACS is compared to lawnmower surveying and to Markov decision process (MDP) planning with two state-of-the-art reward functions: Upper Confidence Bound (UCB) and Maximum Value Information (MVI). The performance of each method is evaluated through comparison of the time it takes to identify a continuous channel through an area, using one, two, three, or four Autonomous Surface Vehicles (ASVs). The performance of each method is compared across ten simulated bathymetry scenarios and one field area, each with different channel layouts. The results from simulations and field trials presented in this thesis indicate that on average multi-vehicle PBACS outperforms lawnmower, UCB, and MVI based methods, with two main exceptions. One case is when lawnmower start locations are aligned with a straight channel, which can happen for any number of vehicles. The lawnmower outperforms other approaches in this case. However, this alignment on an unknown bathymetry would happen purely by chance, while PBACS identifies the channel regardless of any alignment. The second case is when the shape of the channel is curved, and no straight path exists. In this case, PBACS outperforms other approaches only when more than two vehicles are used.S.M