Engineering Commons^™

Evolutionary View Planning For Optimized Uav Terrain Modeling In A Simulated Environment, Ronald A. Martin, Ivan Rojas, Kevin W. Franke, John Hedengren

Faculty Publications

This work demonstrates the use of genetic algorithms in optimized view planning for 3D reconstruction applications using small unmanned aerial vehicles (UAVs). The quality of UAV site models is currently highly dependent on manual pilot operations or grid-based automation solutions. When applied to 3D structures, these approaches can result in gaps in the total coverage or inconsistency in final model resolution. Genetic algorithms can effectively explore the search space to locate image positions that produce high quality models in terms of coverage and accuracy. A fitness function is defined, and optimization parameters are selected through semi-exhaustive search. A novel simulation …

Generation Of Vector Partially Coherent Optical Sources Using Phase-Only Spatial Light Modulators, Milo W. Hyde Iv, Santasri Bose-Pillai, David G. Voelz, Xifeng Xiao

Faculty Publications

A simple and flexible optical system for generating electromagnetic or vector partially coherent sources or beams is presented. The alternative design controls field amplitude (beam shape), coherence, and polarization using only spatial light modulators. This improvement makes the apparatus simpler to construct and significantly increases the flexibility of vector partially coherent source generators by allowing many different types of sources to be produced without changing the physical setup. The system’s layout and theoretical foundations are thoroughly discussed. The utility and flexibility of the proposed system are demonstrated by producing a vector Schell-model and non-Schell-model source. The experimental results are compared …

Predictive Modeling Of A Buoyancy-Operated Cooling Tower Under Unsaturated Conditions: Adjoint Sensitivity Model And Optimal Best-Estimate Results With Reduced Predicted Uncertainties, Federico Di Rocco, Dan Gabriel Cacuci

Faculty Publications

Nuclear and other large-scale energy-producing plants must include systems that guarantee the safe discharge of residual heat from the industrial process into the atmosphere. This function is usually performed by one or several cooling towers. The amount of heat released by a cooling tower into the external environment can be quantified by using a numerical simulation model of the physical processes occurring in the respective tower, augmented by experimentally measured data that accounts for external conditions such as outlet air temperature, outlet water temperature, and outlet air relative humidity. The model’s responses of interest depend on many model parameters including …

A Multi-Value Sequence Generated By Power Residue Symbol And Trace Function Over Odd Characteristic Field, Yasuyuki Nogami, Satoshi Uehara, Kazuyoshi Tsuchiya, Nasima Begum, Hiroto Ino, Robert Morelos-Zaragoza

Faculty Publications

This paper proposes a new multi-value sequence generated by utilizing primitive element, trace, and power residue symbol over odd characteristic finite field. In detail, let p and k be an odd prime number as the characteristic and a prime factor of p-1, respectively. Our proposal generates k-value sequence T={ti | ti=fk(Tr(ωi)+A)}, where ω is a primitive element in the extension field $\F{p}{m}$, Tr(⋅) is the trace function that maps $\F{p}{m} \rightarrow \f{p}$, A is a non-zero scalar in the prime field $\f{p}$, and fk(⋅) is a certain mapping function based on k-th power residue symbol. Thus, the proposed sequence has …

Dual Role Of Sb Ions As Electron Traps And Hole Traps In Photorefractive Sn2P2S6 Crystals, Brant E. Kananen, Eric M. Golden, Sergey A. Basun, D. R. Evans, A. A. Grabar, I. M. Stoika, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton

Faculty Publications

Doping photorefractive single crystals of Sn₂P₂S₆ with antimony introduces both electron and hole traps. In as-grown crystals, Sb³⁺ (5s²) ions replace Sn²⁺ ions. These Sb³⁺ ions are either isolated (with no nearby perturbing defects) or they have a charge-compensating Sn²⁺ vacancy at a nearest-neighbor Sn site. When illuminated with 633 nm laser light, isolated Sb³⁺ ions trap electrons and become Sb²⁺ (5s²5p¹) ions. In contrast, Sb³⁺ ions with an adjacent Sn vacancy trap holes during illumination. The hole is primarily …

Integrated Design Of Downwind Land-Based Wind Turbines Using Analytic Gradients, Andrew Ning, Derek Petch

Faculty Publications

Wind turbines are complex systems where component-level changes can have significant system-level effects. Effective wind turbine optimization generally requires an integrated analysis approach with a large number of design variables. Optimizing across large variable sets is orders of magnitude more efficient with gradient-based methods as compared to gradient-free method, particularly when using exact gradients. We have developed a wind turbine analysis set of over 100 components where 90% of the models provide numerically exact gradients through symbolic differentiation, automatic differentiation, and adjoint methods. This framework is applied to a specific design study focused on downwind land-based wind turbines.

Downwind machines …

Fabrication Of High Performing Pemfc Catalyst-Coated Membranes With A Low Cost Air-Assisted Cylindrical Liquid Jets Spraying System, Xiong Peng, Travis Omasta, William Rigdon, William E. Mustain

Faculty Publications

In this work, a low cost air-assisted cylindrical liquid jets spraying (ACLJS) system was developed to prepare high-performance catalyst-coated membranes (CCMs) for proton exchange membrane fuel cells (PEMFCs). The catalyst ink was flowed from a cylindrical orifice and was atomized by an air stream fed from a coaxial slit and sprayed directly onto the membrane, which was suctioned to a heated aluminum vacuum plate. The CCM pore architecture including size, distribution and volume can be controlled using various flow parameters, and the impact of spraying conditions on electrode structure and PEMFC performance was investigated. CCMs fabricated in the fiber-type break-up …

Material Selection Shape Factors For Compliant Arrays In Bending, David T. Fullwood, Todd G. Nelson, Jared T. Bruton, Nathan E. Rieske, M. Patrick Walton, Larry L. Howell

Faculty Publications

Similar to the general class of metamaterials, compliant arrays (CAs) are engineered from an array of subelements that combine to produce a response that is typically not available from a at panel made of a single material. As such, analysis and design of CA systems requires the integration of both the material and geometrical properties of the array. This paper proposes a convenient and efficient method of combining these essential elements using analytically derived shape factors for bending modes. The approach is validated experimentally, and used to demonstrate large regions of previously inaccessible property combinations in material selection charts that …

Formal Performance Guarantees For Behavior-Based Localization Missions, Damian Lyons, Ron Arkin, Shu Jiang, Matt O'Brien, Feng Tang, Peng Tang

Faculty Publications

Abstract— Localization and mapping algorithms can allow a robot to navigate well in an unknown environment. However, whether such algorithms enhance any specific robot mission is currently a matter for empirical validation. In this paper we apply our MissionLab/VIPARS mission design and verification approach to an autonomous robot mission that uses probabilistic localization software.

Two approaches to modeling probabilistic localization for verification are presented: a high-level approach, and a sample-based approach which allows run-time code to be embedded in verification. Verification and experimental validation results are presented for two different missions, each using each method, demonstrating the accuracy …

Benchmarking Approach For Empirical Comparison Of Pricing Models In Drms, Seif Azghandi, Kenneth M. Hopkinson, Kennard R. Laviers

Faculty Publications

emand response management systems often involve the use of pricing schemes to motivate the efficient use of electrical power. Achieving this efficiency requires the detection of electrical power patterns. The detection of these patterns normally involves use of non-linear, quasi-non-linear, and at times linear data pattern detection models. The behavioural disparities of these models and specifically when used for a specific set of data make it hard to select the most efficient model. The contribution of this study is devising an empirical benchmark (reference) ( perfect ) control pricing (PCP) model through which various models are compared in order to …

Wind Power: Frustrating Yet Inevitable, Garth Woodruff

Faculty Publications

No abstract provided.

Methodology For Simulation And Analysis Of Complex Adaptive Supply Network Structure And Dynamics Using Information Theory, Joshua V. Rodewald, John M. Colombi, Kyle F. Oyama, Alan W. Johnson

Faculty Publications

Supply networks existing today in many industries can behave as complex adaptive systems making them more difficult to analyze and assess. Being able to fully understand both the complex static and dynamic structures of a complex adaptive supply network (CASN) are key to being able to make more informed management decisions and prioritize resources and production throughout the network. Previous efforts to model and analyze CASN have been impeded by the complex, dynamic nature of the systems. However, drawing from other complex adaptive systems sciences, information theory provides a model-free methodology removing many of those barriers, especially concerning complex network …

Measuring Vapor Intrusion: From Source Science Politics To A Transdisciplinary Approach, Peter C. Little, Kelly G. Pennell

Faculty Publications

Investigation of indoor air quality has been on the upswing in recent years. In this article, we focus on how the transport of subsurface vapors into indoor air spaces, a process known as ‘vapor intrusion’, (VI) is defined and addressed. For environmental engineers and physical scientists who specialize in this emerging indoor environmental exposure science, VI is notoriously difficult to characterize, leading the regulatory community to seek improved science-based understandings of VI pathways and exposures. Yet despite the recent growth in VI science and competition between environmental consulting companies, VI studies have largely overlooked the social and political field in …

Vibration Monitoring Via Nano-Composite Piezoelectric Foam Bushings, David T. Fullwood, Evan T. Bird, A Jake Merrell, Brady K. Anderson, Cory N. Newton, Parker G. Rosquist, Anton E. Bowden, Matthew K. Seeley

Faculty Publications

Most mechanical systems produce vibrations as an inherent side effect of operation. Though some vibrations are acceptable in operation, others can cause damage or signal a machine’s imminent failure. These vibrations would optimally be monitored in real-time, without human supervision to prevent failure and excessive wear in machinery. This paper explores a new alternative to currently-used machine-monitoring equipment, namely a piezoelectric foam sensor system. These sensors are made of a silicone-based foam embedded with nano- and micro-scale conductive particles. Upon impact, they emit an electric response that is directly correlated with impact energy, with no electrical power input. In the …

Development And Optimization Of Voltammetry For Real Time Analysis Of Multi-Component Electrorefiner Salt, Chao Zhang, Devin Rappleye, Michael F. Simpson

Faculty Publications

Normal pulse voltammetry was performed on LiCl-KCl-UCl3- MgCl2 molten salt mixtures while varying parameters such as pulse time, relaxation potential, and interval time. Concentrations of UCl3 up to 7 wt% were tested with a fixed 1.5 wt% MgCl2 concentration. The correlation between diffusion limited partial current density to UCl3 concentration exhibited an excellent fit to a 2nd order polynomial. A similar fit was obtained for the correlation between MgCl2 concentration and the diffusion limited partial current density at a fixed UCl3 concentration of 1.0 wt%.

Polynomial Chaos For The Computation Of Annual Energy Production In Wind Farm Layout Optimization, Santiago Padrón, Andrew P.J. Stanley, Jared Thomas, Juan Alonso, Andrew Ning

Faculty Publications

Careful management of wake interference is essential to further improve Annual Energy Production (AEP) of wind farms. Wake effects can be minimized through optimization of turbine layout, wind farm control, and turbine design. Realistic wind farm optimization is challenging because it has numerous design degrees of freedom and must account for the stochastic nature of wind. In this paper we provide a framework for calculating AEP for any relevant uncertain (stochastic) variable of interest. We use Polynomial Chaos (PC) to efficiently quantify the effect of the stochastic variables—wind direction and wind speed—on the statistical outputs of interest (AEP) for wind …

Electronic Properties Of Mos2/Moox Interfaces: Implications In Tunnel Field Effect Transistors And Hole Contacts, Santosh Kc, Roberto Longo, Rafik Addou, Robert Wallace, Kyeongjae Cho

Faculty Publications

In an electronic device based on two dimensional (2D) transitional metal dichalcogenides (TMDs), finding a low resistance metal contact is critical in order to achieve the desired performance. However, due to the unusual Fermi level pinning in metal/2D TMD interface, the performance is limited. Here, we investigate the electronic properties of TMDs and transition metal oxide (TMO) interfaces (MoS2/MoO3) using density functional theory (DFT). Our results demonstrate that, due to the large work function of MoO3 and the relative band alignment with MoS2, together with small energy gap, the MoS2/MoO3 interface is a good candidate for a tunnel field effect …

Investigation Of Shadowing Effects In Typical Propagation Scenarios For High Speed Railway At 2350 Mhz, Liu Liu, Cheng Tao, David W. Matolak, Tao Zhou, Houjin Chen

Faculty Publications

Based on realistic measurements in China, shadowing characteristics at the frequency of 2350 MHz were investigated in typical High-Speed Railway environments. After confirming that the measured shadowing satisfies wide-sense stationarity (assessed via the reverse arrangement test method), we quantify the shadowing correlation. Three types of correlation models are compared for the shadowing characterization, and the Normalized Mean Square Error is used to determine the best matching model: a single decaying exponential function. Decorrelation distances were found to be 11.9 m, 17.7 m, and 8.3 m in our three HSR scenarios, respectively. The results should be useful for the evaluation and …

Landmark Detection With Surprise Saliency Using Convolutional Neural Networks, Feng Tang, Damian Lyons, Daniel Leeds

Faculty Publications

Abstract—Landmarks can be used as reference to enable people or robots to localize themselves or to navigate in their environment. Automatic definition and extraction of appropriate landmarks from the environment has proven to be a challenging task when pre-defined landmarks are not present. We propose a novel computational model of automatic landmark detection from a single image without any pre-defined landmark database. The hypothesis is that if an object looks abnormal due to its atypical scene context (what we call surprise saliency), it then may be considered as a good landmark because it is unique and easy to spot by …

Predictive Modeling Of A Paradigm Mechanical Cooling Tower Model: Ii. Optimal Best-Estimate Results With Reduced Predicted Uncertainties, Ruixian Fang, Dan Gabriel Cacuci, Madalina Badea

Faculty Publications

This work uses the adjoint sensitivity model of the counter-flow cooling tower derived in the accompanying PART I to obtain the expressions and relative numerical rankings of the sensitivities, to all model parameters, of the following model responses: (i) outlet air temperature; (ii) outlet water temperature; (iii) outlet water mass flow rate; and (iv) air outlet relative humidity. These sensitivities are subsequently used within the “predictive modeling for coupled multi-physics systems” (PM_CMPS) methodology to obtain explicit formulas for the predicted optimal nominal values for the model responses and parameters, along with reduced predicted standard deviations for the predicted model parameters …

Predictive Modeling Of A Paradigm Mechanical Cooling Tower: I. Adjoint Sensitivity Model, Dan Gabriel Cacuci, Ruixian Fang

Faculty Publications

Cooling towers discharge waste heat from an industrial process into the atmosphere, and are essential for the functioning of large energy-producing plants, including nuclear reactors. Using a numerical simulation model of the cooling tower together with measurements of outlet air relative humidity, outlet air and water temperatures enables the quantification of the rate of thermal energy dissipation removed from the respective process. The computed quantities depend on many model parameters including correlations, boundary conditions, material properties, etc. Changes in these model parameters will induce changes in the computed quantities of interest (called “model responses”). These changes are quantified by the …

Imaging Right Ventricular Function To Predict Outcome In Pulmonary Arterial Hypertension, Alessandro Bellofiore, Melanie Brewis, Rebecca Vanderpool, Naomi Chesler, Martin Johnson, Robert Naeije, Andrew Peacock

Faculty Publications

Right ventricular (RV) function is a major determinant of outcome in pulmonary arterial hypertension (PAH). However, uncertainty persists about the optimal method of evaluation.MethodsWe measured RV end-systolic and end-diastolic volumes (ESV and EDV) using cardiac magnetic resonance imaging and RV pressures during right heart catheterization in 140 incident PAH patients and 22 controls. A maximum RV pressure (Pmax) was calculated from the nonlinear extrapolations of early and late systolic portions of the RV pressure curve. The gold standard measure of RV function adaptation to afterload, or RV–arterial coupling (Ees/Ea) was estimated by the stroke volume (SV)/ESV ratio (volume method) or …

Thermal Management Using Mems Bimorph Cantilever Beams, Ronald A. Coutu Jr., Robert S. Lafleur, John P. Walton, Laverne A. Starman

Faculty Publications

This paper examines a passive cooling technique using microelectromechanical systems (MEMS) for localized thermal management of electronic devices. The prototype was designed using analytic equations, simulated using finite element methods (FEM), and fabricated using the commercial PolyMUMPs™ process. The system consisted of an electronic device simulator (EDS) and MEMS bimorph cantilever beams (MBCB) array with beams lengths of 200, 250, and 300 μm that were tested to characterize deflection and thermal behavior. The specific beam lengths were chosen to actuate in response to heating associated with the EDS (i.e. the longest beams actuated first corresponding to the hottest portion of …

Using The Gauge Condition To Simplify The Elastodynamic Analysis Of Guided Wave Propagation, Bhuiyan Yeasin Md, Victor Giurgiutiu

Faculty Publications

In this article, gauge condition in elastodynamics is explored more to revive its potential capability of simplifying wave propagation problems in elastic medium. The inception of gauge condition in elastodynamics happens from the Navier-Lame equations upon application of Helmholtz theorem. In order to solve the elastic wave problems by potential function approach, the gauge condition provides the necessary conditions for the potential functions. The gauge condition may be considered as the superposition of the separate gauge conditions of Lamb waves and shear horizontal (SH) guided waves respectively, and thus, it may be resolved into corresponding gauges of Lamb waves and …

Scenario Analysis For Techno-Economic Model Development Of U.S. Offshore Wind Support Structures, Rick Damiani, Andrew Ning, Ben Maples, Aaron Smith, Katherine Dykes

Faculty Publications

Challenging bathymetry and soil conditions of future U.S. offshore wind power plants might promote the use of multimember, fixed-bottom structures (or “jackets”) in place of monopiles. Support structures affect costs associated with the balance of system (BOS) and operation and maintenance. Understanding the link between these costs and the main environmental design drivers is crucial in the quest for a lower levelized cost of energy (LCOE), and it is the main rationale for this work. Actual cost and engineering data are still scarce; hence, we evaluated a simplified engineering approach to tie key site and turbine parameters (e.g., water depth, …

Direct Bandgap Cross-Over Point Of Ge1-YSnY Grown On Si Estimated Through Temperature-Dependent Photoluminescence Studies, Thomas R. Harris, Mee-Yi Ryu, Yung Kee Yeo, Buguo Wang, C. L. Senaratne

Faculty Publications

Epitaxial Ge_1-ySn_y (y = 0%–7.5%) alloys grown on either Si or Ge-buffered Si substrates by chemical vapor deposition were studied as a function of Sn content using temperature-dependent photoluminescence (PL). PL emission peaks from both the direct bandgap (Γ-valley) and the indirect bandgap (L-valley) to the valence band (denoted by E_D and EID, respectively) were clearly observed at 125 and 175 K for most Ge_1-ySn_y samples studied. At 300 K, however, all of the samples exhibited dominant E_D emission with either very weak or no measureable E_ID emission. At 10 K, …

A New Open Source Platform For Lowering The Barrier For Environmental Web App Development, Nathan R. Swain, Scott D. Christensen, Alan D. Snow, Herman Dolder, Gonzola Espinoza-Dávalos, Erfan Goharian, Norman L. Jones, E. James Nelson, Daniel P. Ames, Steven J. Burian

Faculty Publications

The interactive nature of web applications or “web apps” makes them a well-suited medium for conveying complex scientific concepts to lay audiences and creating decision support tools that harness cutting edge modeling techniques and promote the work of environmental scientists and engineers. Despite this potential, the technical expertise required to develop web apps represents a formidable barrier—even for scientists and engineers who are skilled programmers. This paper describes four hurdles that contribute to this barrier and introduces an approach to overcoming these hurdles. We present an open source implementation of this approach, a development and hosting environment for environmental web …

Open-Loop Electrowetting Actuation With Micro-Stepping, Qi Ni, Daniel E. Capecci, Nathan B. Crane

Faculty Publications

Microfluidic-driven mechanical actuation opens new possibilities for positioning and manipulating delicate small components. However, existing microfluidic actuation methods are not well-suited to positioning with high resolution. This paper reports a method for precise, open-loop control of droplet position in finite steps by varying the duty cycle of the input signal in electrowetting actuation. When wetted to a solid object, both the droplet and the solid can be actuated. Unlike conventional electrowetting actuation methods, positioning resolution in our proposed method can be much smaller than the size of the underlying electrodes without requiring closed loop feedback control system. Using a leaky …

Performance Of Dynamically Simulated Reference Patterns For Cross Correlation Ebsd, Brian Jackson, Jordan Christensen, Saransh Singh, Marc De Graef, David T. Fullwood, Eric Richards Homer, Robert Wagoner

Faculty Publications

High-resolution (or \cross-correlation") electron backscatter diffraction analysis (HR-EBSD) utilizes cross-correlation techniques to determine relative orientation and distortion of an experimental electron backscatter diffraction pattern (EBSP) with respect to a reference pattern. The integrity of absolute strain and tetragonality measurements of a standard Si/SiGe material have previously been analyzed using reference patterns produced by kinematical simulation. While the results were promising, the noise levels were significantly higher for kinematically produced patterns, compared to real patterns taken from the Si region of the sample. This paper applies HR-EBSD techniques to analyze lattice distortion in a Si/SiGe sample, using recently developed dynamically simulated …

Application Of Voltammetry For Electroanalytical Measurement Of Concentrations In Lacl3-Mgcl2 Mixtures In Eutectic Licl-Kcl, Zhonghang Wang, Devin Rappleye, C S. Yang, Michael Simpson

Faculty Publications

For electroanalytical measurement of molten chloride salts, various voltammetry methods have been used on mixtures of MgCl₂ and LaCl₃ in eutectic LiCl-KCl. These salt mixtures are of primary interest to spent nuclear fuel electrorefining systems. MgCl₂ is used as a surrogate for PuCl₃, while LaCl₃ represents rare earth fission product salts. Cyclic voltammetry scans with these salt mixtures exhibited extra peaks, presumably due to underpotential deposition of La(III) ions onto Mg. Quantitatively, the current contribution from each peak was best determined using normal pulse voltammetry and fit to the Cottrell equation. This yielded linear …