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Articles 1 - 13 of 13
Full-Text Articles in Chemical Engineering
Sexual Recombination And Increased Mutation Rate Expedite Evolution Of Escherichia Coli In Varied Fitness Landscapes, George Peabody, Hao Li, Katy Kao
Sexual Recombination And Increased Mutation Rate Expedite Evolution Of Escherichia Coli In Varied Fitness Landscapes, George Peabody, Hao Li, Katy Kao
Faculty Publications
Sexual recombination and mutation rate are theorized to play different roles in adaptive evolution depending on the fitness landscape; however, direct experimental support is limited. Here we examine how these factors affect the rate of adaptation utilizing a “genderless” strain of Escherichia coli capable of continuous in situ sexual recombination. The results show that the populations with increased mutation rate, and capable of sexual recombination, outperform all the other populations. We further characterize two sexual and two asexual populations with increased mutation rate and observe maintenance of beneficial mutations in the sexual populations through mutational sweeps. Furthermore, we experimentally identify …
Combined Model Predictive Control And Scheduling With Dominant Time Constant Compensation, Logan Beal, Junho Park, Damon Petersen, Sean C. Warnick, John Hedengren
Combined Model Predictive Control And Scheduling With Dominant Time Constant Compensation, Logan Beal, Junho Park, Damon Petersen, Sean C. Warnick, John Hedengren
Faculty Publications
Linear model predictive control is extended to both control and optimize a product grade schedule. The proposed methods are time-scaling of the linear dynamics based on throughput rates and grade-based objectives for product scheduling based on a mathematical program with complementarity constraints. The linear model is adjusted with a residence time approximation to time-scale the dynamics based on throughput. Although nonlinear models directly account for changing dynamics, the model form is restricted to linear differential equations to enable fast online cycle times for large-scale and real-time systems. This method of extending a linear time-invariant model for scheduling is designed for …
Insights On Osmotic Tolerance Mechanisms In Escherichia Coli Gained From An Rpoc Mutation, Yuqi Guo, James Winkler, Katy Kao
Insights On Osmotic Tolerance Mechanisms In Escherichia Coli Gained From An Rpoc Mutation, Yuqi Guo, James Winkler, Katy Kao
Faculty Publications
An 84 bp in-frame duplication (K370_A396dup) within the rpoC subunit of RNA polymerase was found in two independent mutants selected during an adaptive laboratory evolution experiment under osmotic stress in Escherichia coli, suggesting that this mutation confers improved osmotic tolerance. To determine the role this mutation in rpoC plays in osmotic tolerance, we reconstructed the mutation in BW25113, and found it to confer improved tolerance to hyperosmotic stress. Metabolite analysis, exogenous supplementation assays, and cell membrane damage analysis suggest that the mechanism of improved osmotic tolerance by this rpoC mutation may be related to the higher production of acetic acid …
Potential Benefits Of Combining Anomaly Detection With View Planning For Uav Infrastructure Modeling, R. Abraham Martin, Landen Blackburn, Joshua Pulsipher, Kevin W. Franke, John Hedengren
Potential Benefits Of Combining Anomaly Detection With View Planning For Uav Infrastructure Modeling, R. Abraham Martin, Landen Blackburn, Joshua Pulsipher, Kevin W. Franke, John Hedengren
Faculty Publications
This paper presents a novel method for UAV-based 3D modeling of large infrastructure objects, such as pipelines, canals and levees, that combines anomaly detection with automatic on-board 3D view planning. The study begins by assuming that anomaly detections are possible and focuses on quantifying the potential benefits of the combined method and the view planning algorithm. A simulated canal environment is constructed, and several simulated anomalies are created and marked. The algorithm is used to plan inspection flights for the anomaly locations, and simulated images from the flights are rendered and processed to construct 3D models of the locations of …
A Multi-Fluid Model For Microstructure Formation In Polymer Membranes, Douglas R. Tree, Kris T. Delaney, Hector D. Ceniceros, Tatsuhiro Iwama, Glenn H. Fredrickson
A Multi-Fluid Model For Microstructure Formation In Polymer Membranes, Douglas R. Tree, Kris T. Delaney, Hector D. Ceniceros, Tatsuhiro Iwama, Glenn H. Fredrickson
Faculty Publications
We develop a multi-fluid model for a ternary polymer solution using the Rayleighian formalism of Doi and Onuki, and give an efficient pseudo-spectral method for solving both the diffusion and momentum equations that result. Subsequently, we find that the numerical simulation is capable of describing systems at the micron length-scale and easily reaches millisecond time-scales. In addition, we characterize the model thermodynamics and kinetics including the (i) phase behavior, (ii) structure of the interfaces, (iii) mutual diffusion coefficients, (iv) bulk spinodal decomposition kinetics with and without hydrodynamics and (v) spinodal decomposition in the presence of an interface with a non-solvent …
Hybrid Concentrated Solar Thermal Power Systems: A Review, Kody M. Powell, Khalid Rashid, Kevin Ellingwood, Jake Tuttle, Brian D. Iverson
Hybrid Concentrated Solar Thermal Power Systems: A Review, Kody M. Powell, Khalid Rashid, Kevin Ellingwood, Jake Tuttle, Brian D. Iverson
Faculty Publications
Concentrated solar power (CSP), or solar thermal power, is an ideal technology to hybridize with other energy technologies for power generation. CSP shares technology with conventional power generation and can be readily integrated with other energy types into a synergistic system, which has many potential benefits including increased dispatchability and reliability, improved efficiency, reduced capital costs through equipment sharing, and the opportunity for flexible operation by alternating between energy sources. Another advantage of CSP technology is the ability to readily store via thermal energy storage (TES), making the intermittent solar resource dispatchable. A review of CSP hybridization strategies with coal, …
Comprehensive Model Of Single Particle Pulverized Coal Combustion Extended To Oxy-Coal Conditions, Troy Michael Holland, Thomas H. Fletcher
Comprehensive Model Of Single Particle Pulverized Coal Combustion Extended To Oxy-Coal Conditions, Troy Michael Holland, Thomas H. Fletcher
Faculty Publications
Oxy-fired coal combustion is a promising potential carbon capture technology. Predictive CFD simulations are valuable tools in evaluating and deploying oxy-fuel and other carbon capture technologies either as retrofit technologies or for new construction. However, accurate predictive simulations require physically realistic submodels with low computational requirements. In particular, comprehensive char oxidation and gasification models have been developed that describe multiple reaction and diffusion processes. This work extends a comprehensive char conversion code (CCK), which treats surface oxidation and gasification reactions as well as processes such as film diffusion, pore diffusion, ash encapsulation, and annealing. In this work several submodels in …
Optimal Combined Long-Term Facility Design And Short-Term Operational Strategy For Chp Capacity Investments, Jose Mojica, Damon Petersen, Brigham Hansen, Kody Powell, John Hedengren
Optimal Combined Long-Term Facility Design And Short-Term Operational Strategy For Chp Capacity Investments, Jose Mojica, Damon Petersen, Brigham Hansen, Kody Powell, John Hedengren
Faculty Publications
This work presents a detailed case study for the optimization of the expansion of a district energy system evaluating the investment decision timing, type of capacity expansion, and fine-scale operational modes. The study develops an optimization framework to find the investment schedule over 30 years with options of investing in traditional heating sources (boilers) or a next-generation combined heat and power (CHP) plant that provides heat and electricity. In district energy systems, the selected capacity and type of system is dependent on demand-side requirements, energy prices, and environmental costs. This work formulates capacity planning over a time horizon as a …
Modeling Effects Of Annealing On Coal Char Reactivity To O2 And Co2, Based On Preparation Conditions, Troy Michael Holland, Sham Bhat, Peter Marcy, James Gattiker, Joel D. Kress, Thomas H. Fletcher
Modeling Effects Of Annealing On Coal Char Reactivity To O2 And Co2, Based On Preparation Conditions, Troy Michael Holland, Sham Bhat, Peter Marcy, James Gattiker, Joel D. Kress, Thomas H. Fletcher
Faculty Publications
Oxy-fired coal combustion is a promising potential carbon capture technology. Predictive computational fluid dynamics (CFD) simulations are valuable tools in evaluating and deploying oxyfuel and other carbon capture technologies, either as retrofit technologies or for new construction. However, accurate predictive combustor simulations require physically realistic submodels with low computational requirements. A recent sensitivity analysis of a detailed char conversion model (Char Conversion Kinetics (CCK)) found thermal annealing to be an extremely sensitive submodel. In the present work, further analysis of the previous annealing model revealed significant disagreement with numerous datasets from experiments performed after that annealing model was developed. The …
Semi-Empirical Model For Fire Spread In Shrubs With Spatially-Defined Fuel Elements And Flames, Dallan Prince, Chen Shen, Thomas H. Fletcher
Semi-Empirical Model For Fire Spread In Shrubs With Spatially-Defined Fuel Elements And Flames, Dallan Prince, Chen Shen, Thomas H. Fletcher
Faculty Publications
A semi-empirical model was developed which forms shrub geometries from distinct fuel elements (e.g. leaves) and describes flame spread from element to element. Ignition, flame growth and flame decay patterns were based on combustion data of single leaves. Extension of the model to various heating conditions was achieved by scaling the flame growth parameters using physics-based heat transfer models. The resulting model offers a novel approach to examine fire spread and to explicitly describe both distinct fuel elements and fire behavior. This approach balances computational speed and modeling detail while providing a unique perspective into fire spread phenomena. Comparisons of …
Modeling Soot Oxidation And Gasification With Bayesian Statistics, Alexander Jon Josephson, Neal D. Gaffin, Sean T. Smith, Thomas H. Fletcher, David Lignell
Modeling Soot Oxidation And Gasification With Bayesian Statistics, Alexander Jon Josephson, Neal D. Gaffin, Sean T. Smith, Thomas H. Fletcher, David Lignell
Faculty Publications
This paper presents a statistical method for model calibration using data collected from literature. The method is used to calibrate parameters for global models of soot consumption in combustion systems. This consumption is broken into two different submodels: first for oxidation where soot particles are attacked by certain oxidizing agents; second for gasification where soot particles are attacked by H2O or CO2 molecules. Rate data were collected from 19 studies in the literature and evaluated using Bayesian statistics to calibrate the model parameters. Bayesian statistics are valued in their ability to quantify uncertainty in modeling. The calibrated consumption model with …
Model For The Evolution Of Pore Structure In A Lignite Particle During Pyrolysis. 2. Influence Of Cross-Linking Reactions, Molten Metaplast, And Molten Ash On Particle Surface Area, He Yang, Thomas H. Fletcher, Sufen Li, Haoquan Hu, Lijun Li
Model For The Evolution Of Pore Structure In A Lignite Particle During Pyrolysis. 2. Influence Of Cross-Linking Reactions, Molten Metaplast, And Molten Ash On Particle Surface Area, He Yang, Thomas H. Fletcher, Sufen Li, Haoquan Hu, Lijun Li
Faculty Publications
A model for the evolution of the pore structure in a lignite particle during pyrolysis was established previously based on the chemical percolation devolatilization (CPD) model, using coal polymer network parameters to calculate the surface area and porosity of the particle. In this paper, to get the accurate surface area of coal particle at high pyrolysis temperature, the previous model was improved by considering the effects of cross-linking reactions, molten Metaplast, and ash. The good agreement of the predicted surface area with experiments at temperature below 1200 K in the previous model is maintained, and model accuracy is improved at …
Study Potential Of Indigenous Pseudomonas Aeruginosa And Bacillus Subtilis In Bioremediation Of Diesel-Contaminated Water, Mohammad-Saeed Safdari, Hamid-Reza Kariminia, Zahra Ghobadi Nejad, Thomas H. Fletcher
Study Potential Of Indigenous Pseudomonas Aeruginosa And Bacillus Subtilis In Bioremediation Of Diesel-Contaminated Water, Mohammad-Saeed Safdari, Hamid-Reza Kariminia, Zahra Ghobadi Nejad, Thomas H. Fletcher
Faculty Publications
Petroleum products which are used in a wide variety of industries as energy sources and raw materials have become a major concern in pollution of terrestrial and marine environments. The purpose of this study was to assess the potential of indigenous microbial isolates for degradation of diesel fuel. Two most proficient bacterial strains among five isolated strains from polluted soil of an industrial refinery were studied. The isolates then were identified as Pseudomonas aeruginosa and Bacillus subtilis using biochemical tests and 16S rRNA gene sequence analyses. P. aeruginosa showed higher biodegradation efficiency than B. subtilis in shaking flask containing diesel-contaminated …