Computational Engineering Commons^™

Employee-Task Assignments For Organization Modeling: A Review Of Models And Applications, Cansu Kandemir, Holly A. H. Handley, S. Long (Ed.), E.-H. Ng (Ed.), C. Downing (Ed.)

Engineering Management & Systems Engineering Faculty Publications

In this study, we present a review of task assignment problems in organizations, an area that has become more important as tasks become more complex and personnel skills become more specialized. The challenge is to design task assignments that meet all requirements and result in the best organizational performance. The consequences of poor design include failed tasks, reduced efficiency, and inability to meet deadlines. Moreover, inequity of workload between employees can cause lack of job satisfaction, loss of motivation and also boredom.

In general, work processes in organizations consist of different tasks, which require different expertise. Personnel usually have various …

Numerical Analysis Of Biodiesel Combustion In A Direct Injection Compression Ignition Engine, Kyle D. Morse

College of Graduate Studies: Theses & Dissertations

In this work, simulations of the combustion reaction within an optical Sandia/Cummins N14 direct-injection compression ignition engine are conducted. First, validation of the spray model against liquid and vapor penetration data was conducted using a trial and error method. Secondly, the overall engine model was validated against pressure and temperature data across high and low temperature combustion regimes. The third phase of the work was focused on creating a combustion model for biodiesel. The fourth and final phase was to test the biodiesel combustion model in the pertinent combustion regimes. The agreement with common trends in emissions of biodiesel combustion …

Importance Of Sources Using The Repeated Fusion Method And The Proportional Conflict Redistribution Rules #5 And #6, Florentin Smarandache, Jean Dezert

Branch Mathematics and Statistics Faculty and Staff Publications

We present in this paper some examples of how to compute by hand the PCR5 fusion rule for three sources, so the reader will better understand its mechanism. We also take into consideration the importance of sources, which is different from the classical discounting of sources.

Approximations To The Solution Of The Frank-Kamenetskii Equation In A Spherical Geometry, Moustafa A. Soliman

Chemical Engineering

In this paper, an approximate analytical solution for Frank-Kamenetskii equation modeling a thermal explosion in a sphere, is obtained. The approximate solution is obtained by perturbation methods in terms of small and large distance parameter. The approximate solution is compared with the numerical solution obtained from an initial value problem formulation to the original boundary value problem. The approximate solution obtained is valid for all values of the distance parameter. For the original boundary value problem and for a given Frank-Kamenetskii parameter, a nonlinear algebraic equation needs to be solved to be able to apply the approximate solution.

A Modified Orthogonal Collocation Method For Reaction Diffusion Problems, Moustafa A. Soliman, Yousef S. Al-Zeghayer, Abdelhamid M. Ajbar

Chemical Engineering

A low-order collocation method is often useful in revealing the main features such as concentration and temperature profiles and the effectiveness factor for porous catalyst particles. Two modifications are introduced in this paper to make the method more efficient. The first modification is to add an extra collocation point at the center of the particle. It is shown that such extra point introduces a single variable non-linear equation to be solved after obtaining the standard collocation method solution. In the second modification, the polynomial solution obtained from the application of the orthogonal collocation method is transformed to a rational function …

Model-Based Energy Analysis Of An Integrated Midrex-Based Iron/Steel Plant, Abdelhamid M. Ajbar, Khalid I. Alhumaizi, Moustafa A. Soliman, Emadadeen Ali

Chemical Engineering

This article presents modeling and simulations of an integrated plant for the production of steel using the direct reduced iron (DRI)=electric arc furnace (EAF) route. In a previous work (Alhumaizi et al., 2012), a comprehensive mathematical model of an iron plant based on MIDREX technology was developed, validated, and simulated. In this article, the model is extended to account for an empirical model of an EAF plant. Numerical simulations were carried out for the effect of different operating parameters of the integrated plant. Useful profiles as well as a summary table were compiled to illustrate the results of the sensitivity …

Experimental Investigation Of Mist Film Cooling And Feasibility Study Of Mist Transport In Gas Turbines, Reda M. Ragab

LSU New Orleans Theses and Dissertations

In the modern advanced gas turbines, the turbine inlet temperature may exceed 1500°C as a requirement to increase power output and thermal efficiency. Therefore, it is imperative that the blades and vanes are cooled so they can withstand these extreme temperatures. Film cooling is a cooling technique widely used in high-performance gas turbines. However, the film cooling effectiveness has almost reached plateau, resulting in a bottleneck for continuous improvement of gas turbines' efficiency.

In this study, an innovative cooling scheme, mist film cooling is investigated through experiments. A small amount of tiny water droplets with an average diameter about 10-15 …

A New Software Framework For Unstructured Mesh Representation And Manipulation, Craig R. Tanis

Masters Theses and Doctoral Dissertations

This research presents a unique new software framework for representing and manipulating unstructured meshes in parallel, for use in modern scientific simulation codes. Due to the central nature of the unstructured mesh, this framework provides a variety of functionality, desirable throughout the lifecycle of an application, such as IO, parallel partitioning, phantom node data updates, adaptive refinement, derefinement and load balancing. What makes the framework unique is a focus on generality: like a database, the user provides a programmatic schema defining the structure of the mesh, including topological descriptions of the valid mesh entities. The system extracts adjacency information from …

Stabilized Finite Elements For Compressible Turbulent Navier-Stokes, Jon Taylor Erwin

Masters Theses and Doctoral Dissertations

In this research a stabilized finite element approach is utilized in the development of a high-order flow solver for compressible turbulent flows. The Reynolds averaged Navier-Stokes (RANS) equations and modified Spalart-Almaras (SA) turbulence model are discretized using the streamline/upwind Petrov-Galerkin (SUPG) scheme. A fully implicit methodology is used to obtain steady state solutions or to drive unsteady problems at each time step. Order of accuracy is assessed for inviscid and viscous flows in two and three dimensions via the method of manufactured solutions. Proper treatment of curved surface geometries is of vital importance in high-order methods, especially when high aspect …

Extension Of A High-Order Petrov-Galerkin Implementation Applied To Non-Radiating And Radar Cross Section Geometries, William L. Shoemake

Masters Theses and Doctoral Dissertations

Capabilities of a high-order Petrov-Galerkin solver are expanded to include N-port systems. Tait-Bryan angles are employed to launch electro-magnetic waves in arbitrary directions allowing off axis ports to be driven. The transverse-electric (TE) formulation is added allowing waveguide geometries to be driven directly. A grid convergence study is performed on a coax-driven waveguide system. Physical data are matched to a hybrid-T junction (magic-T) electromagnetic waveguide structure to verify the TE driving formulation along with the Tait-Bryan angles and modified post-processing routines. A simple sphere case is used to exercise the radar cross section (RCS) routines and to examine the benefits …

2-D Cfd Design Of The Cross-Sectional Shape Of Arterial Stents, Kristen Karman

Masters Theses and Doctoral Dissertations

An approach for desigining arterial stents to maximize wall shear stress is presented. A cost equation to maximize wall shear stress is derived and then inverted into a minimization problem for the optimizer. A 2-D mixed-element finite-volume scheme for solving the compressible Navier-Stokes equations is implemented. A paramaterization of the cross- sectional shape of the stent wire using Hicks-Henne functions is described. The strategies used in the commercial optimization software, DAKOTA, to minimize the cost equation are described. The solver is validated using well known fluid flow test cases and is shown to match other published computed results for bloodflow …

Action Potential Simulation Of The Hirudo Medicinalis's Retzius Cell In Matlab, Zechari Ryan Tempesta

Master's Theses

Modification of Hodgkin and Huxley’s experimentally derived set of nonlinear differential equations was implemented to accurately simulate the action potential of the Hirudo Medicinalis’s Retzius cell in MATLAB under analogous conditions to those found in the Retzius cell environment. The voltage-gated sodium and potassium channel responses to changes in membrane potential, as experimentally determined by Hodgkin and Huxley, were manipulated to suit simulation parameters established by electrophysiological Retzius cell recordings. Application of this methodology permitted additional accurate simulation of the Hirudo Medicinalis’s P cell under analogous conditions to those found in the P cell environment. Further refinement of this technique …

Artist-Driven Fracturing Of Polyhedral Surface Meshes, Tyler Casella

Master's Theses

This paper presents a robust and artist driven method for fracturing a surface polyhedral mesh via fracture maps. A fracture map is an undirected simple graph with nodes representing positions in UV-space and fracture lines along the surface of a mesh. Fracture maps allow artists to concisely and rapidly define, edit, and apply fracture patterns onto the surface of their mesh.

The method projects a fracture map onto a polyhedral surface and splits its triangles accordingly. The polyhedral mesh is then segmented based on fracture lines to produce a set of independent surfaces called fracture components, containing the visible surface …

Improving Safety In Medical Devices From Concept To Retirements, Martin Mchugh, Fergal Mccaffery, Silvana Macmahon, Anita Finnega

Books/Book Chapters

As with many domains the use of software within the healthcare industry is on the rise [1, 2] within the last 20 years.

Higher-Order Petrov-Galerkin Methods For Analysis Of Antennas, Xueying Zhang

Masters Theses and Doctoral Dissertations

A temporally and spatially high-order accurate Petrov-Galerkin finite-element method is applied to the analysis of several antenna configurations. The method obtains numerical solutions of Maxwell's equations in the time domain using implicit time stepping and introduces energy into the domain using a Gaussian pulse to allow frequency-domain parameters to be computed over a range of frequencies with a single time-dependent solution. Verification cases for a monopole antenna and a microstrip patch antenna are used to examine the accuracy of the algorithm. Effects of varying antenna parameters on subsequent performance metrics are discussed based on the results from the simulations. Post-processing …

Validation Of Interpolative Interfaces For Rotorcraft Applications, Adam L. Cofer

Masters Theses and Doctoral Dissertations

The study uses computational methods to simulate fluid flow on the NASA ROBIN helicopter model and on a simplified rotor geometry previously tested at Mississippi State. The ROBIN model and the rotor are run using an unstructured grid. Results from the Tenasi flow solver are compared against both simulated and wind tunnel data. Tenasi is an unstructured, Reynolds Averaged Navier-Stokes (RANS) solver developed at the SimCenter: National Center for Computational Engineering, located at the University of Tennessee at Chattanooga. Steady-state results for the isolated ROBIN fuselage and unsteady results for both fuselage and rotor systems are computed. In the unsteady …

Physics-Based Point Placement By Particle Dynamics Simulation, Philip Wesley Fackler

Masters Theses and Doctoral Dissertations

A physics-based approach to point cloud distribution for mesh generation is investigated using inter-nodal attraction and repulsion forces based on the Lennard-Jones pair potential and a simplified particle dynamics simulation. This method produces smooth distributions of points which accurately correspond to desired scalar spacing fields. Resulting point distributions are triangulated using Lawson's algorithm and the quality of these resulting meshes is measured, demonstrating the effectiveness of the approach. Several features planned for future development for increasing the robustness and versatility of the proposed method are discussed.

Leveraging Apple Remote Desktop To Facilitate Classroom Critiques Of Digital Projects, Jerry C. Schnepp

Visual Communications and Technology Education Faculty Publications

Classroom critiquing of visual projects is an essential exercise to help students refine their work. Usually, instructors display student work on a large screen so that the class can offer comments and suggestions. However, problems arise because critiques are often mired by ambiguous or misunderstood language. Sometimes students are better shown than told. This presentation demonstrates how Apple Remote Desktop (ARD) can be used to project the display of any lab computer while the instructor and student share control. The student’s work can be interactively modified during a critique session, resulting in an engaging experience for the entire class.

Computer Simulation Study Of Slipper Lubrication In Hydraulic Machines, Jordyn B. Miller, Monika Ivantysynova

The Summer Undergraduate Research Fellowship (SURF) Symposium

Hydraulic pumps and motors are vital components used in many applications today. Specifically, the axial piston pump is important because it is reliable, relatively compact, and has a high horsepower-to-weight ratio. These features make this type of pump very advantageous in hydraulic systems. Maintaining proper lubrication between surfaces in an axial pump, such as the slipper and swashplate, is imperative in order to have smooth operation of the system and prevent metal-to-metal contact. The aim of this research is to find the optimal slipper design and fluid film thickness to simultaneously maintain a balanced pressure and decrease power loss in …

Direct Simulation Monte Carlo Simulation Toolkit For Equilibrium (0d) And Planar Couette Flow (1d), Austin I. Saragih, Alina A. Alexeenko

The Summer Undergraduate Research Fellowship (SURF) Symposium

Visualized simulation tool of Direct Simulation Monte Carlo (DSMC) is essential in aeronautical engineering and gas dynamics, by presenting information that can educate engineers and scientists to preliminarily understand the molecular gas dynamics and direct simulation of gas flows. Two educational tools and models are described for rarified gas flows and simulated particle collisions. A 0-Dimensional DSMC in approach to translational equilibrium was developed to simulate the speed distribution over time and the comparison between the final distribution and the Maxwell-Boltzmann distribution. A 1-Dimensional DSMC for Planar Couette flow was also developed to calculate the number of strikes of the …

Data Workflow In Large Scale Simulations Of Blood Flow In Aneurysms, Paolo Di Achille, Jay D. Humphrey

Yale Day of Data

Aneurysms are responsibile for significant morbidity and mortality, and there is a need for an increased understanding of all the aspects of the natural history of these lesions. We are currently working to extend our analyses with the goal of creating models of aneurysmal progression that are able to predict rupture risk through the description of the evolving geometry, structure, properties, and loads.

Realization of patient specific models of the blood circulation necessitates a complex computationally and data intensive procedure that starts from the collection of medical images in a clinical setting and encompasses several stages of data processing on …

Parallel Implementations Of The Frank-Wolfe Algorithms For The Traffic Assignment Problem, Shawn Eugene Allen

Computational Modeling & Simulation Engineering Theses & Dissertations

Transportation planners seek to understand how to best invest limited resources for future transportation network development. The traffic assignment problem is one algorithm of great importance to planners because it provides insight into how traffic will flow within the network. The Frank-Wolfe algorithm is a traditional solution method for this optimization problem, but it has been characterized by its slow rate of convergence and poor computational performance. This thesis examines and implements several modern advancements in this algorithm which are designed to improve the rate of convergence.

In addition to algorithm changes, another method to improve the performance of an …

Using Real Property Layouts To Study The Foreclosure Contagion Effect In Real Estate With Agent-Based Modeling And Simulation, Daniele Vernon-Bido

Computational Modeling & Simulation Engineering Theses & Dissertations

Foreclosures in the United States increased sharply from 2007 to 2009. These foreclosures had a spillover effect on neighboring property values causing additional foreclosures. This is known as the foreclosure contagion effect.

Recent studies have quantified the discount attributed to foreclosure contagion using equation-based techniques. However, the discount varied between studies and markets. Further studies using agent-based modeling and simulation have demonstrated the relationship between the discounts, the time a foreclosure remains on the market, the prevailing interest rates and the average property values.

This study uses agent-based modeling and simulation (ABMS) to explore the differences that varying neighborhood densities …

Binaural Spatialization For 3d Immersive Audio Communication In A Virtual World, Davide Andrea Mauro, Rufael Mekuria, Michele Sanna

Computer Sciences and Electrical Engineering Faculty Research

Realistic 3D audio can greatly enhance the sense of presence in

a virtual environment. We introduce a framework for capturing,

transmitting and rendering of 3D audio in presence of other

bandwidth savvy streams in a 3D Tele-immersion based virtual

environment. This framework presents an efficient implementation

for 3D Binaural Spatialization based on the positions of current

objects in the scene, including animated avatars and on the fly

reconstructed humans. We present a general overview of the

framework, how audio is integrated in the system and how it can

exploit the positions of the objects and room geometry to render

realistic …

Examples Where The Conjunctive And Dempster’S Rules Are Insensitive, Florentin Smarandache, Jean Dezert, Valeri Kroumov

Branch Mathematics and Statistics Faculty and Staff Publications

In this paper we present several counter-examples to the Conjunctive rule and to Dempster rule of combinations in information fusion.

Adaptive Co-Scheduler For Highly Dynamic Resources, Kartik Vedalaveni

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

There are many kinds of scientific applications that run on high throughput computational (HTC) grids. HTC may utilize clusters opportunistically, only running on a given cluster when it is otherwise idle. These widely dispersed HTC clusters are heterogeneous in terms of capability and availability, but can provide significant computing power in aggregate. The scientific algorithms run on them also vary greatly. Some scientific algorithms might use high rates of disk I/O and some might need large amounts of RAM. Most schedulers only consider cpu availability, but unchecked demand on these associated resources that aren’t managed by resource managers may give …

Creating A Package In R, Brit Schneiders, Eric Archer

STAR Program Research Presentations

In a time of increasingly efficient technology and data production, scientists are producing data faster than it can be analyzed. Therefore, user accessibility to data analysis is becoming more and more critical. In general, researchers have a set of raw data and want an efficient means to their final analysis. A package serves as that means by creating a set of functions and making them accessible to the user. Often, a user has a small piece of code to run (a single R script, for example), and that script requires the use of certain functions, which are contained in a …

Network Dynamics Of Visual Naming, Christopher R. Conner

Dissertations and Theses (Open Access)

Recognition and naming of objects and actions are fundamental components of language. They involve several different systems working in coordination to accomplish a complex behavior. During visual naming, sensory and semantic processing are carried out by dedicated cortical substrates in the temporal and occipital lobes, while response selection and articulatory planning are handled by prefrontal cortex. Despite decades of research using lesion analysis, functional MRI and electro-encephalography, the precise dynamics involved remain unknown due to the inadequate spatio-temporal resolution of these methodologies. Of particular interest is the organization of semantic knowledge and the degree of serial and parallel organization of …

Preconditioning Methods For Ideal And Multiphase Fluid Flows, Ashish Gupta

Masters Theses and Doctoral Dissertations

The objective of this study is to develop a preconditioning method for ideal and multiphase multispecies compressible fluid flow solver using homogeneous equilibrium mixture model. The mathematical model for fluid flow going through phase change uses density and temperature in the formulation, where the density represents the multiphase mixture density. The change of phase of the fluid is then explicitly determined using the equation of state of the fluid, which only requires temperature and mixture density. The method developed is based on a finite-volume framework in which the numerical fluxes are computed using Roe’s [1] approximate Riemann solver and the …

Computational Investigation Of The Effects Of Casing Treatments On The Performance Of A Turbofan, Weiyang Lin

Masters Theses and Doctoral Dissertations

A computational survey focused on modifications to the casing near the rotor blade tip is carried out for the purpose of enhancing the performance and increasing the stall margin of a model turbofan stage in transonic operating conditions. The study is divided into three phases. During the first phase two types of casing treatments, inward protruding rings and circumferential grooves, were tested with relatively coarse grids. In the second phase, a grid resolution study is carried out with the results from this phase influencing the choices for the third stage. In the third phase, a comprehensive study is performed to …