Engineering Commons^™

Techno-Economic And Fluid Dynamics Analysis For Growing Microalgae With The Intent Of Producing Biofuel Using A System Model, Leah R. Raffaeli

Electronic Theses and Dissertations

Techno-economic and systems studies on microalgal growth scenarios to date are abbreviated and missing a number of important variables. By including these variables in a detailed model integrating biology, chemistry, engineering, and financial aspects, a more defined systems analysis is possible. Through optimizing the model productivity based on the resulting net profit, the system analysis results in a more accurate assessment of environmental and economic sustainability of specific algal growth scenarios. Photobioreactor algal growth scenario optimization in the system model has resulted in realistic engineering design requirements based on algal growth requirements and fluid dynamics analysis. Results show feasibility for …

Identification Of Hemodynamically Optimal Coronary Stent Designs Based On Vessel Caliber, Timothy J. Gundert, Alison L. Marsden, Weiguang Yang, David S. Marks, John F. Ladisa

Biomedical Engineering Faculty Research and Publications

Coronary stent design influences local patterns of wall shear stress (WSS) that are associated with neointimal growth, restenosis, and the endothelialization of stent struts. The number of circumferentially repeating crowns N_C for a given stent de- sign is often modified depending on the target vessel caliber, but the hemodynamic implications of altering N_C have not previously been studied. In this investigation, we analyzed the relationship between vessel diameter and the hemodynamically optimal N_C using a derivative-free optimization algorithm coupled with computational fluid dynamics. The algorithm computed the optimal vessel diameter, defined as minimizing the area of stent-induced …

Feasibility Analysis Of Estrification Systems With Entrainers, Kang Wook Lee

Dissertations and Theses

(Ethyl Acetate) and IPA (Isopropyl Acetate) production systems are studied in terms of the feasibility analysis. It is not feasible to retrieve pure products by a simple reactive distillation for IPA production system because CCR (Critical Composition Region) covers the entire desired binary edge for IPA system. On the other hand, even though CCR does not cover the entire desired binary edge of the EA system completely, internal reflux ratio (IRR) analysis does not allow the production of the pure product via reactive distillation for EA production system. To overcome the restraints, external entrainers are utilized to take advantage of …

Comparative Study On Posture And Its Influences On Horizontal Ground Reaction Forces Generated By Muscles: Implications For Crouch Gait, Hoa Xuan Hoang

Masters Theses

Crouch gait decreases walking efficiency due to the increased knee and hip flexion during the stance phase of gait. Crouch gait is generally considered to be disadvantageous for patients with cerebral palsy; however, a crouched posture may afford biomechanical advantages that lead some patients to adopt a crouch gait.

To investigate one possible advantage of crouch gait, a musculoskeletal model created in OpenSim was placed in 15 different postures from upright to severe crouch during initial, middle, and final stance of the gait cycle. A series of optimizations were performed for each posture to maximize ground reaction forces for the …

Improving Cardiovascular Stent Design Using Patient-Specific Models And Shape Optimization, Timothy J. Gundert

Master's Theses (2009 -)

Stent geometry influences local hemodynamic alterations (i.e. the forces moving blood through the cardiovascular system) associated with adverse clinical outcomes. Computational fluid dynamics (CFD) is frequently used to quantify stent-induced hemodynamic disturbances, but previous CFD studies have relied on simplified device or vascular representations. Additionally, efforts to minimize stent-induced hemodynamic disturbances using CFD models often only compare a small number of possible stent geometries. This thesis describes methods for modeling commercial stents in patient-specific vessels along with computational techniques for determining optimal stent geometries that address the limitations of previous studies.

An efficient and robust method was developed for virtually …

A Study On Facility Planning Using Discrete Event Simulation: Case Study Of A Grain Delivery Terminal., Sarah M. Asio

Department of Industrial and Management Systems Engineering: Dissertations, Theses, and Student Research

The application of traditional approaches to the design of efficient facilities can be tedious and time consuming when uncertainty and a number of constraints exist. Queuing models and mathematical programming techniques are not able to capture the complex interaction between resources, the environment and space constraints for dynamic stochastic processes. In the following study discrete event simulation is applied to the facility planning process for a grain delivery terminal. The discrete event simulation approach has been applied to studies such as capacity planning and facility layout for a gasoline station and evaluating the resource requirements for a manufacturing facility. To …

The Conversion Of Low-Grade Heat Into Power Using Supercritical Rankine Cycles, Huijuan Chen

USF Tampa Graduate Theses and Dissertations

Low-grade heat sources, here defined as below 300 ºC, are abundantly available as industrial waste heat, solar thermal, and geothermal, to name a few. However, they are under-exploited for conversion to power because of the low efficiency of conversion. The utilization of low-grade heat is advantageous for many reasons. Technologies that allow the efficient conversion of low-grade heat into mechanical or electrical power are very important to develop.

This work investigates the potential of supercritical Rankine cycles in the conversion of low-grade heat into power. The performance of supercritical Rankine cycles is studied using ChemCAD linked with customized excel macros …

Validating Pareto Optimal Operation Parameters Of Polyp Detection Algorithms For Ct Colonography, Jiang Li, Adam Huang, Nicholas Petrick, Jianhua Yao, Ronald M. Summers, Maryellen L. Giger (Ed.), Nico Karssemeijer (Ed.)

Electrical & Computer Engineering Faculty Publications

We evaluated a Pareto front-based multi-objective evolutionary algorithm for optimizing our CT colonography (CTC) computer-aided detection (CAD) system. The system identifies colonic polyps based on curvature and volumetric based features, where a set of thresholds for these features was optimized by the evolutionary algorithm. We utilized a two-fold cross-validation (CV) method to test if the optimized thresholds can be generalized to new data sets. We performed the CV method on 133 patients; each patient had a prone and a supine scan. There were 103 colonoscopically confirmed polyps resulting in 188 positive detections in CTC reading from either the prone or …

Comparison Of Optimization Methodologies For Sustained-Yield Groundwater Pumping Planning In East Shore Area, Utah, Shu Takahashi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Combined simulation and optimization models, which are helpful for long-term groundwater planning of complex nonlinear aquifer systems, are developed using alternative modelling approaches. The models incorporate a representation of steady-state, quasi-three-dimensional head response to pumping within an optimization. An embedding model which describes exactly the nonlinear flow of an unconfined aquifer is presented. In contrast with the embedding models presented in the Utah State University Ground Water Model, it directly achieves the optimal solution without a "cycling." To address the nonlinearity of the flow system, response matrix models couple superposition with the cycling procedure. Their linear influence coefficients are generated …