Digital Commons Network^™

Abmscore: A Heuristic Algorithm For Forming Strategic Coalitions In Agent-Based Simulation, Andrew J. Collins, Gayane Grigoryan

Engineering Management & Systems Engineering Faculty Publications

Integrating human behavior into agent-based models has been challenging due to its diversity. An example is strategic coalition formation, which occurs when an individual decides to collaborate with others because it strategically benefits them, thereby increasing the expected utility of the situation. An algorithm called ABMSCORE was developed to help model strategic coalition formation in agent-based models. The ABMSCORE algorithm employs hedonic games from cooperative game theory and has been applied to various situations, including refugee egress and smallholder farming cooperatives. This paper discusses ABMSCORE, including its mechanism, requirements, limitations, and application. To demonstrate the potential of ABMSCORE, a new …

Numerical Analysis Of A Roadway Piezoelectric Harvesting System, Abdul Rahman Badawi

Mechanical & Aerospace Engineering Theses & Dissertations

Highways, streets, bridges, and sidewalks with heavy traffic dissipate a considerable amount of waste mechanical energy every day. Piezoelectric energy harvesting devices are a very promising technology that can convert the waste mechanical energy to clean and renewable energy to enhance the sustainability of infrastructures. Research efforts in large-scale energy harvesting have led to the advancement of piezoelectric devices to the point that large-scale implementation is starting to become more feasible. The energy harvested by these devices can be used in many ways such as providing heating or cooling, melting ice, monitoring structural conditions in bridges and tunnels, and powering …

Latent Choice Models To Account For Misclassification Errors In Discrete Transportation Data, Lacramioara Elena Balan

Civil & Environmental Engineering Theses & Dissertations

One of the most fundamental tasks when it comes to analyzing data using statistical methods is to understand the relationship between the explanatory variables and the outcome. Misclassification of explanatory variables is a common risk when using statistical modeling techniques. In this dissertation, we define ‘misclassification,’ as a response that is reported or recorded in the wrong category; for example, a variable is registered as a one when it should have the value zero. Misclassification can easily happen in any data; for example, in an interview setting where the respondent misunderstands the question or the interviewer checks the wrong box. …

Effects Of Sea Level Rise On Hydrology: Case Study In A Typical Mid-Atlantic Coastal Watershed, Xixi Wang, Rui Li, Homa Jalaeian Taghadomi, Shohreh Pedram, Xiao Zhao

Civil & Environmental Engineering Faculty Publications

Sea level rise (SLR) can negatively affect the hydrology of coastal watersheds. However, the relevant information is incomplete and insufficient in existing literature. The objective of this study is to present a modeling approach to predict long-term effects of SLR on changes of flood peak, flood stage, and groundwater table with an assumption that the historical climate would reoccur in the future. The study was conducted for a typical coastal watershed in southeast USA. The results indicate that sea level had been rising at a rate of 4.21 mm yr⁻¹ from 1948 to 1982 but at a faster rate …

Impact Of Trucking Network Flow On Preferred Biorefinery Locations In The Southern United States, Timothy M. Young, Lee D. Han, James H. Perdue, Stephanie R. Hargrove, Frank M. Guess, Xia Huang, Chung-Hao Chen

Electrical & Computer Engineering Faculty Publications

The impact of the trucking transportation network flow was modeled for the southern United States. The study addresses a gap in existing research by applying a Bayesian logistic regression and Geographic Information System (GIS) geospatial analysis to predict biorefinery site locations. A one-way trucking cost assuming a 128.8 km (80-mile) haul distance was estimated by the Biomass Site Assessment model. The "median family income," "timberland annual growth-to-removal ratio," and "transportation delays" were significant in determining mill location. Transportation delays that directly impacted the costs of trucking are presented. A logistic model with Bayesian inference was used to identify preferred site …

Multi-Scale Visualization Of Molecular Architecture Using Real-Time Ambient Occlusion In Sculptor, Manuel Wahle, Willy Wriggers

Mechanical & Aerospace Engineering Faculty Publications

The modeling of large biomolecular assemblies relies on an efficient rendering of their hierarchical architecture across a wide range of spatial level of detail. We describe a paradigm shift currently under way in computer graphics towards the use of more realistic global illumination models, and we apply the so-called ambient occlusion approach to our opensource multi-scale modeling program, Sculptor. While there are many other higher quality global illumination approaches going all the way up to full GPU-accelerated ray tracing, they do not provide size-specificity of the features they shade. Ambient occlusion is an aspect of global lighting that offers great …

Dimensionless Criteria For Selecting Tidally-Influenced Advective-Dispersive Desalination Brine Mixing Plume Characterization Models, Alireza Shahvari

Civil & Environmental Engineering Theses & Dissertations

The very nature of requirements for implementing a desalination process is highly spatial due to the need to secure both a source for the operation and sink for brine dilution. Thus, the applicable coastal location is bound to natural tidal mixing characteristics and subjected to a near- or a far-field availability for source and sink. Mixing characteristics of coastal waters are very different from one point to another due to the spatiotemporal tidal characteristic in loco in a manner that it can vary from being highly advective to completely dispersive dominant. Once a location is identified, estimation of corresponding water …

Measurement System Characterization In The Presence Of Measurement Errors, Sean A. Como

Mechanical & Aerospace Engineering Theses & Dissertations

In the calibration of a measurement system, data are collected in order to estimate a mathematical model between one or more factors of interest and a response. Ordinary least squares is a method employed to estimate the regression coefficients in the model. The method assumes that the factors are known without error; yet, it is implicitly known that the factors contain some uncertainty. In the literature, this uncertainty is known as measurement error. The measurement error affects both the estimates of the model coefficients and the prediction, or residual, errors. There are some methods, such as orthogonal least squares, that …

The Reduction Of Storm Surge By Vegetation Canopies: Three-Dimensional Simulations, Y. Peter Sheng, Andrew Lapetina, Gangfeng Ma

Civil & Environmental Engineering Faculty Publications

Significant buffering of storm surges by vegetation canopies has been suggested by limited observations and simple numerical studies, particularly following recent Hurricanes Katrina, Rita, and Wilma. Here we simulate storm surge and inundation over idealized topographies using a three-dimensional vegetation-resolving storm surge model coupled to a shallow water wave model and show that a sufficiently wide and tall vegetation canopy reduces inundation on land by 5 to 40 percent, depending upon various storm and canopy parameters. Effectiveness of the vegetation in dissipating storm surge and inundation depends on the intensity and forward speed of the hurricane, as well as the …

Colonel Blotto Games And Lancaster's Equations: A Novel Military Modeling Combination, Andrew Collins, Patrick T. Hester

VMASC Publications

Military strategists face a difficult task when engaged in a battle against an adversarial force. They have to predict both what tactics their opponent will employ and the outcomes of any resultant conflicts in order to make the best decision about their actions. Game theory has been the dominant technique used by analysts to investigate the possible actions that an enemy will employ. Traditional game theory can be augmented by use of Lanchester equations, a set of differential equations used to determine the outcome of a conflict. This paper demonstrates a novel combination of game theory and Lanchester equations using …

Selection Of Source And Use Of Traffic Information In Emergency Situations, R. Michael Robinson, Asad Khattak

VMASC Publications

The access and the use of advanced traveler information systems (ATISs) by drivers during normal commuting have been extensively assessed and analyzed. Emergency managers and transportation officials have extended the results of studies of ATIS use under routine conditions to emergency scenarios under the assumption that drivers' responses to information under emergency conditions mimic those seen under normal driving conditions. A recent survey of potential hurricane evacuees suggests the need to revisit this assumption. Results indicate that although commercial radio reports and variable message signs continue to be the sources of traffic information cited the most frequently, other information sources …

Individualized Cognitive Modeling For Close-Loop Task Mitigation, Guangfan Zhang, Roger Xu, Wei Wang, Jiang Li, Tom Schnell, Mike Keller, Thomas E. Pinelli (Ed.)

Electrical & Computer Engineering Faculty Publications

An accurate real-time operator functional state assessment makes it possible to perform task management, minimize risks, and improve mission performance. In this paper, we discuss the development of an individualized operator functional state assessment model that identifies states likely leading to operational errors. To address large individual variations, we use two different approaches to build a model for each individual using its data as well as data from subjects with similar responses. If a subject's response is similar to that of the individual of interest in a specific functional state, all the training data from this subject will be used …

Simulations Of Nanopore Formation And Phosphatidylserine Externalization In Lipid Membranes Subjected To A High-Intensity, Ultrashort Electric Pulse, Q. Hu, R. P. Joshi, K. H. Schoenbach

Bioelectrics Publications

A combined MD simulator and time dependent Laplace solver are used to analyze the electrically driven phosphatidylserine externalization process in cells. Time dependent details of nanopore formation at cell membranes in response to a high-intensity (100kV∕cm), ultrashort (10ns) electric pulse are also probed. Our results show that nanosized pores could typically be formed within about 5ns. These predictions are in very good agreement with recent experimental data. It is also demonstrated that defect formation and PS externalization in membranes should begin on the anode side. Finally, the simulations confirm that PS externalization is a nanopore facilitated event, rather than the …

Models, Composability, And Validity, Eric Werner Weisel

Computational Modeling & Simulation Engineering Theses & Dissertations

Composability is the capability to select and assemble simulation components in various combinations into simulation systems to satisfy specific user requirements. The defining characteristic of composability is the ability to combine and recombine components into different simulation systems for different purposes. The ability to compose simulation systems from repositories of reusable components has been a highly sought after goal among modeling and simulation developers. The expected benefits of robust, general composability include reduced simulation development cost and time, increased validity and reliability of simulation results, and increased involvement of simulation users in the process. Consequently, composability is an active research …

Improved Energy Model For Membrane Electroporation In Biological Cells Subjected To Electrical Pulses, R. P. Joshi, Q. Hu, K. H. Schoenbach, H. P. Hjalmarson

Bioelectrics Publications

A self-consistent model analysis of electroporation in biological cells has been carried out based on an improved energy model. The simple energy model used in the literature is somewhat incorrect and unphysical for a variety of reasons. Our model for the pore formation energy E(r) includes a dependence on pore population and density. It also allows for variable surface tension, incorporates the effects of finite conductivity on the electrostatic correction term, and is dynamic in nature. Self-consistent calculations, based on a coupled scheme involving the Smoluchowski equation and the improved energy model, are presented. It is shown that E(r) becomes …

Mechanism For Membrane Electroporation Irreversibility Under High-Intensity, Ultrashort Electrical Pulse Conditions, R. P. Joshi, K. H. Schoenbach

Bioelectrics Publications

An improved electroporation model is used to address membrane irreversibility under ultrashort electric pulse conditions. It is shown that membranes can survive a strong electric pulse and recover provided the pore distribution has a relatively large spread. If, however, the population consists predominantly of larger radii pores, then irreversibility can result. Physically, such a distribution could arise if pores at adjacent sites coalesce. The requirement of close proximity among the pore sites is more easily satisfied in smaller organelles than in outer cell membranes. Model predictions are in keeping with recent observations of cell damage to intracellular organelles (e.g., mitochondria), …

Theoretical Predictions Of Electromechanical Deformation Of Cells Subjected To High Voltages For Membrane Electroporation, R. P. Joshi, Q. Hu, K. H. Schoenbach, H. P. Hjalmarson

Bioelectrics Publications

An electromechanical analysis based on thin-shell theory is presented to analyze cell shape changes in response to external electric fields. This approach can be extended to include osmotic-pressure changes. Our calculations demonstrate that at large fields, the spherical cell geometry can be significantly modified, and even ellipsoidal forms would be inappropriate to account for the deformation. Values of the surface forces obtained from our calculations are in very good agreement with the 1–10 mN/m range for membrane rupture reported in the literature. The results, in keeping with reports in the literature, demonstrate that the final shape depends on membrane thickness. …

Self-Consistent Simulations Of Electroporation Dynamics In Biological Cells Subjected To Ultrashort Electrical Pulses, R. P. Joshi, Q. Hu, R. Aly, K. H. Schoenbach, H. P. Hjalmarson

Bioelectrics Publications

The temporal dynamics of electroporation of cells subjected to ultrashort voltage pulses are studied based on a coupled scheme involving the Laplace, Nernst-Plank, and Smoluchowski equations. A pore radius dependent energy barrier for ionic transport, accounts for cellular variations. It is shown that a finite time delay exists in pore formation, and leads to a transient overshoot of the transmembrane potential V_mem beyond 1.0 V. Pore resealing is shown to consist of an initial fast process, a 10⁻⁴s delay, followed by a much slower closing at a time constant of about 10 ⁻¹s. This establishes a …

Thermal Lattice Boltzmann Simulation For Multispecies Fluid Equilibration, Linda L. Vahala, Darren Wah, George Vahala, Jonathan Carter, Pavol Pavlo

Electrical & Computer Engineering Faculty Publications

The equilibration rate for multispecies fluids is examined using thermal lattice Boltzmann simulations. Two-dimensional free-decay simulations are performed for effects of velocity shear layer turbulence on sharp temperature profiles. In particular, parameters are so chosen that the lighter species is turbulent while the heavier species is laminar-and so its vorticity layers would simply decay and diffuse in time. With species coupling, however, there is velocity equilibration followed by the final relaxation to one large co- and one large counter-rotating vortex. The temperature equilibration proceeds on a slower time scale and is in good agreement with the theoretical order of magnitude …

Study Of Human Factors Variables In Battle Outcome Prediction Models, David Andrew Glovier

Engineering Management & Systems Engineering Theses & Dissertations

Over time there have been many improvements in models that are used to predict the outcome of battles. Currently there is much supposition and speculation surrounding the use of human performance related factors as additional inputs to battle simulation models to improve their accuracy. However there is no conclusive scientific evidence which shows that these factors do make a significant difference. This study investigates the use of factors that may impact on the human performance directly or indirectly in battle prediction models. These factors consist of traditional human factors and external factors that may influence the human performance. The research …

The Study Of Wave-Blocking And Current Effects On Nonlinear Interactions Of Shallow-Water Waves Using Advanced Boussinesq Models, Qin Chen

Civil & Environmental Engineering Theses & Dissertations

The first part of this work focuses on the derivation of enhanced Boussinesq-type equations for the combined motion of waves and currents in shallow water areas.

The strategy proposed in this work is to couple two known methods which are the sponge layer concept suitable for short waves and Sommerfeld radiation condition for currents. This coupling method provides satisfactory non-reflective boundaries for the simulation of fully coupled wave/current motion as demonstrated by the numerical experiments. We verify the model against the well known solutions based on the existing theories and good agreement has been observed. The numerical results confirm the …

The Progressive Failure Analysis Of Cut Slope In Anisotropic Strain Softening Soils, Jong Woon Choi

Civil & Environmental Engineering Theses & Dissertations

The failure phenomena in earth structures such as slopes and embankments on clay foundations are a consequence of the formation of failure surfaces.

A finite difference computer code, FLAC (Itasca Consulting Group, 1993), with the isotropic Mohr-Coulomb plasticity model, is used to analyze the undrained progressive failure of a strain softening soil during a slope excavation process. The focus of the study is on the short-term stability of slopes. In the first series of analyses, which are aimed at the evaluation of anisotropic strength effect on slope stability, the isotropic Mohr-Coulomb plasticity model is slightly modified to implement the anisotropic …