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Articles 1 - 13 of 13
Full-Text Articles in Engineering
Swarm-Based Design Of Proportional Integral And Derivative Controllers Using A Compromise Cost Function: An Arduino Temperature Laboratory Case Study, Paulo De Moura Oliveira, John Hedengren, Eduardo Solteiro Pires
Swarm-Based Design Of Proportional Integral And Derivative Controllers Using A Compromise Cost Function: An Arduino Temperature Laboratory Case Study, Paulo De Moura Oliveira, John Hedengren, Eduardo Solteiro Pires
Faculty Publications
Simple and easy to use methods are of great practical demand in the design of Proportional, Integral, and Derivative (PID) controllers. Controller design criteria are to achieve a good set-point tracking and disturbance rejection with minimal actuator variation. Achieving satisfactory trade-offs between these performance criteria is not easily accomplished with classical tuning methods. A particle swarm optimization technique is proposed to design PID controllers. The design method minimizes a compromise cost function based on both the integral absolute error and control signal total variation criteria. The proposed technique is tested on an Arduino-based Temperature Control Laboratory (TCLab) and compared with …
Using Reactive Dissipative Particle Dynamics To Understand Local Shape Manipulation Of Polymer Vesicles, Qinyu Zhu, Timothy R. Scott, Douglas R. Tree
Using Reactive Dissipative Particle Dynamics To Understand Local Shape Manipulation Of Polymer Vesicles, Qinyu Zhu, Timothy R. Scott, Douglas R. Tree
Faculty Publications
Biological cells have long been of interest to researchers due to their capacity to actively control their shape. Accordingly, there is significant interest in generating simplified synthetic protocells that can alter their shape based on an externally or internally generated stimulus. To date, most progress has been made towards controlling the global shape of a protocell, whereas less is known about generating a local shape change. Here, we seek to better understand the possible mechanisms for producing local morphological changes in a popular protocell system, the block copolymer vesicle. Accordingly, we have combined Dissipative Particle Dynamics (DPD) and the Split …
Mechanisms Of Asymmetric Membrane Formation In Nonsolvent-Induced Phase Separation, Jan Ulric Garcia, Tatsuhiro Iwama, Eva Y. Chan, Douglas R. Tree, Kris T. Delaney, Glenn H. Fredrickson
Mechanisms Of Asymmetric Membrane Formation In Nonsolvent-Induced Phase Separation, Jan Ulric Garcia, Tatsuhiro Iwama, Eva Y. Chan, Douglas R. Tree, Kris T. Delaney, Glenn H. Fredrickson
Faculty Publications
We report the first simulations of nonsolvent-induced phase separation (NIPS) that predict membrane microstructures with graded asymmetric pore size distribution. In NIPS, a polymer solution film is immersed in a nonsolvent bath, enriching the film in nonsolvent, and leading to phase separation that forms a solid polymer-rich membrane matrix and polymer-poor membrane pores. We demonstrate how mass-transfer-induced spinodal decomposition, thermal fluctuations, and glass-transition dynamics—implemented with mobility contrast between the polymer-rich and polymer-poor phases—are essential to the formation of asymmetric membrane microstructures. Specifically, we show that the competition between the propagation of the phase-separation and glass-transition fronts determines the degree of …
A Review Of Coal Heating Value Correlations With Application To Coal Char, Tar, And Other Fuels, Andrew P. Richards, Denver Haycock, Jacob F. Frandsen, Thomas H. Fletcher
A Review Of Coal Heating Value Correlations With Application To Coal Char, Tar, And Other Fuels, Andrew P. Richards, Denver Haycock, Jacob F. Frandsen, Thomas H. Fletcher
Faculty Publications
Accurately measuring a fuel’s heating value is one of the first steps in the classification of a new fuel. Heating values are widely used in coal combustion research and are becoming more useful in other fuel types as well. Many different empirical correlations to predict heating values based on primary organic (CHONS) elemental composition are found in the literature, many of which were originally created to predict heating values of parent coal, and some of which have been extended for biomass. However, no correlations exist for heating values of coal chars and tars. Thirteen literature heating value correlations (10 model …
Survey Of 8 Uav Set-Covering Algorithms For Terrain Photogrammetry, Joshua Hammond, Cory Vernon, Trent Okeson, Benjamin Barrett, Samuel Arce, Valerie Newell, Joseph Janson, Kevin Franke, John Hedengren
Survey Of 8 Uav Set-Covering Algorithms For Terrain Photogrammetry, Joshua Hammond, Cory Vernon, Trent Okeson, Benjamin Barrett, Samuel Arce, Valerie Newell, Joseph Janson, Kevin Franke, John Hedengren
Faculty Publications
Remote sensing with unmanned aerial vehicles (UAVs) facilitates photogrammetry for environmental and infrastructural monitoring. Models are created with less computational cost by reducing the number of photos required. Optimal camera locations for reducing the number of photos needed for structure-from-motion (SfM) are determined through eight mathematical set-covering algorithms as constrained by solve time. The algorithms examined are: traditional greedy, reverse greedy, carousel greedy (CG), linear programming, particle swarm optimization, simulated annealing, genetic, and ant colony optimization. Coverage and solve time are investigated for these algorithms. CG is the best method for choosing optimal camera locations as it balances number of …
Automated 3d Reconstruction Using Optimized View-Planning Algorithms For Iterative Development Of Structure-From-Motion Models, Samuel Arce, Cory Vernon, Joshua Hammond, Valerie Newell, Joseph Janson, Kevin Franke, John Hedengren
Automated 3d Reconstruction Using Optimized View-Planning Algorithms For Iterative Development Of Structure-From-Motion Models, Samuel Arce, Cory Vernon, Joshua Hammond, Valerie Newell, Joseph Janson, Kevin Franke, John Hedengren
Faculty Publications
Unsupervised machine learning algorithms (clustering, genetic, and principal component analysis) automate Unmanned Aerial Vehicle (UAV) missions as well as the creation and refinement of iterative 3D photogrammetric models with a next best view (NBV) approach. The novel approach uses Structure-from-Motion (SfM) to achieve convergence to a specified orthomosaic resolution by identifying edges in the point cloud and planning cameras that “view” the holes identified by edges without requiring an initial model. This iterative UAV photogrammetric method successfully runs in various Microsoft AirSim environments. Simulated ground sampling distance (GSD) of models reaches as low as 3.4 cm per pixel, and generally, …
Model Predictive Control And Estimation Of Managed Pressure Drilling Using A Real-Time High Fidelity Flow Model, Junho Park, Cameron Price, David Pixton, Manuel Aghito, Roar Nybø, Knut Bjørkevoll, John Hedengren
Model Predictive Control And Estimation Of Managed Pressure Drilling Using A Real-Time High Fidelity Flow Model, Junho Park, Cameron Price, David Pixton, Manuel Aghito, Roar Nybø, Knut Bjørkevoll, John Hedengren
Faculty Publications
When drilling an oil or gas well, well pressures may be controlled using a technology called managed pressure drilling. This technology often relies on model predictive control schemes; however, practical limitations have generally led to the use of simplified controller models that do not optimally handle certain perturbations in the physical system. The present work reports on the first implementation of a highly accurate system model that has been adapted for real-time use in a controller. This real-time high-fidelity model approximates the results of offline high-fidelity models without requiring operation by model experts. The effectiveness of the model is demonstrated …
Chemical And Thermal Sintering Of Supported Metals With Emphasis On Cobalt Catalysts During Fischer−Tropsch Synthesis, Mahmood Rahmati, Mohammad-Saeed Safdari, Thomas H. Fletcher, Morris D. Argyle, Calvin H. Bartholomew
Chemical And Thermal Sintering Of Supported Metals With Emphasis On Cobalt Catalysts During Fischer−Tropsch Synthesis, Mahmood Rahmati, Mohammad-Saeed Safdari, Thomas H. Fletcher, Morris D. Argyle, Calvin H. Bartholomew
Faculty Publications
This comprehensive critical review combines, for the first time, recent advances in nanoscale surface chemistry, surface science, DFT, adsorption calorimetry, and in situ XRD and TEM to provide new insights into catalyst sintering. This work provides qualitative and quantitative estimates of the extent and rate of sintering as functions of nanocrystal (NC) size, temperature, and atmosphere. This review is unique in that besides summarizing important, useful data from previous studies, it also advances the field through addition of (i) improved or new models, (ii) new data summarized in original tables and figures, and (iii) new fundamental perspectives into sintering of …
Benchmark Temperature Microcontroller For Process Dynamics And Control, Junho Park, Ronald Abraham Martin, Jeffrey Kelly, John Hedengren
Benchmark Temperature Microcontroller For Process Dynamics And Control, Junho Park, Ronald Abraham Martin, Jeffrey Kelly, John Hedengren
Faculty Publications
Standard benchmarks are important repositories to establish comparisons between competing model and control methods, especially when a new method is proposed. This paper presents details of an Arduino micro-controller temperature control lab as a benchmark for modeling and control methods. As opposed to simulation studies, a physical benchmark considers real process characteristics such as the requirement to meet a cycle time, discrete sampling intervals, communication overhead with the process, and model mismatch. An example case study of the benchmark is quantifying an optimization approach for a PID controller with 5.4% improved performance. A multivariate example shows the quantified performance improvement …
Comparison Of Pyrolysis Of Live Wildland Fuels Heated By Radiation Vs. Convection, Mohammad-Saeed Safdari, Elham Amini, David R. Weise, Thomas H. Fletcher
Comparison Of Pyrolysis Of Live Wildland Fuels Heated By Radiation Vs. Convection, Mohammad-Saeed Safdari, Elham Amini, David R. Weise, Thomas H. Fletcher
Faculty Publications
During wildland fires, which include both planned (prescribed fire) and unplanned (wildfire) fires, live and dead plants may be subject to both radiative and convective heat transfer mechanisms. In this study, the pyrolysis of 14 live plant species native to the forests of the southern United States was investigated using a flat-flame burner (FFB) apparatus under three heating modes in order to mimic pyrolysis of plants during wildland fires. The heating modes were: (1) radiation-only, where the plants were pyrolyzed under a moderate heating rate of 4 °C s−1 (radiative flux of 50 kW m−2); (2) convection-only, where the FFB …
Modeling The Influence Of Changes In Aliphatic Structure On Char Surface Area During Coal Pyrolysis, He Yang, Thomas H. Fletcher, Yang Li, Lijun Jin, Sufen Li, Yan Shang, Haoquan Hu
Modeling The Influence Of Changes In Aliphatic Structure On Char Surface Area During Coal Pyrolysis, He Yang, Thomas H. Fletcher, Yang Li, Lijun Jin, Sufen Li, Yan Shang, Haoquan Hu
Faculty Publications
The influence of changes in aliphatic structure on char surface area during coal pyrolysis was modeled, and the effect was introduced to a previous char surface area model for lignite pyrolysis established based on the chemical percolation devolatilization (CPD) model. The modified model can predict not only the N2 and CO2 char surface area during rapid pyrolysis of three lignites but also the CO2 char surface area of two high-volatile bituminous coals; the agreement of the modified model with experiments is improved at high temperatures. The decrease in aliphatic chain length can reduce adsorption positions around aromatic core, and decrease …
Evaluation Of Nox‑Reduction Measures For Iron-Ore Rotary Kilns, Rikard Ekland, Thomas Allguren, Christian Fredriksson, Denver Haycock, Colson Johnson, Jacob Fransen, Thomas H. Fletcher, Klas Andersson
Evaluation Of Nox‑Reduction Measures For Iron-Ore Rotary Kilns, Rikard Ekland, Thomas Allguren, Christian Fredriksson, Denver Haycock, Colson Johnson, Jacob Fransen, Thomas H. Fletcher, Klas Andersson
Faculty Publications
The grate-kiln process is employed for sintering and oxidation of iron-ore pellets. In this process, a fuel (typically coal) is combusted with a large amount of excess air in a rotary kiln, and the high air-to-fuel ratio leads to significant NOx formation. The current Article is an assessment of NOx reduction measures that have been tested in pilot-scale and in full-scale by the Swedish iron-ore company Luossavaara-Kiirunavaara Aktiebolag (LKAB). The results show that the scaling between the full-scale kiln and the pilot-scale kiln is crucial, and several primary measures that reduce NOx significantly in pilot-scale achieve negligible reduction in full-scale. …
Chemical And Thermal Sintering Of Supported Metals With Emphasis On Cobalt Catalysts During Fischer−Tropsch Synthesis, Mahmood Rahmati, Mohammad-Saeed Safdari, Thomas H. Fletcher, Morris D. Argyle, Calvin H. Bartholomew
Chemical And Thermal Sintering Of Supported Metals With Emphasis On Cobalt Catalysts During Fischer−Tropsch Synthesis, Mahmood Rahmati, Mohammad-Saeed Safdari, Thomas H. Fletcher, Morris D. Argyle, Calvin H. Bartholomew
Faculty Publications
This comprehensive critical review combines, for the first time, recent advances in nanoscale surface chemistry, surface science, DFT, adsorption calorimetry, and in situ XRD and TEM to provide new insights into catalyst sintering. This work provides qualitative and quantitative estimates of the extent and rate of sintering as functions of nanocrystal (NC) size, temperature, and atmosphere. This review is unique in that besides summarizing important, useful data from previous studies, it also advances the field through addition of (i) improved or new models, (ii) new data summarized in original tables and figures, and (iii) new fundamental perspectives into sintering of …