Engineering Commons^™

Wind-Induced Exchange In Semi-Enclosed Basins, Rosario Sanay

OES Theses and Dissertations

The wind-induced circulation over laterally varying bathymetry was investigated in homogeneous and in stratified systems using the three-dimensional Regional Ocean Model (ROMS). For homogeneous systems, the focus was to describe the influence of the earth's rotation on the lateral distribution of the flow with particular emphasis on the transverse circulation. Along-basin wind-stress with no rotation caused a circulation dominated by an axially symmetric transverse structure consisting of downwind flow over the shoals and upwind flow in the channel along the whole domain. Transverse circulation was important only at the head of the system where the water sank and reversed direction …

Photonic Crystals: Modeling And Simulation, Shangping Guo

Electrical & Computer Engineering Theses & Dissertations

Photonic crystals are periodic electromagnetic media in optical wavelength scale. They possess photonic band gaps (PBGs) that inhibit the existence of light within the crystals in certain wavelength range. Such band gaps produce many interesting optical phenomena. In this dissertation, the frequency (plane wave method, PWM) and time domain (finite difference time domain method, FDTD) methods are developed for their modeling and simulation.

The theory and algorithm of plane wave method are studied in detail and implemented in a unique and efficient approach. PWM is used to obtain the gap and mode information of ideal and defective photonic crystals. Several …

Development Of A Multicriteria Spatial Decision Support System With Application To The Economic Optimization Of Aircraft Based Weather Data Collection, Ganzague Erol Osman Ozan

Engineering Management & Systems Engineering Theses & Dissertations

This research is motivated by the economic optimization of the Troposherical Airborne Meteorological Data Reporting (TAMDAR), an aircraft-based meteorological data collection system. In the envisioned TAMDAR system, meteorological data collected by the onboard sensors of selected aircraft are transmitted to the ground as aircraft fly their missions. The data is processed by a national center, which disseminates the data to diverse users such as weather forecasters and aviation control centers. Substantial government funding is required for the implementation and operation of this new data acquisition system and data transmission expenditures constitute the largest portion of the costs. To achieve economic …

Nonlinear Response And Fatigue Estimation Of Aerospace Curved Surface Panels To Acoustic And Thermal Loads, Adam Przekop

Mechanical & Aerospace Engineering Theses & Dissertations

This work presents a finite element modal formulation for large amplitude free vibration of arbitrary laminated composite shallow shells. The system equations of motion are formulated first in the physical structural-node degrees of freedom (DOF). Then, the system is transformed into general Duffing-type modal equations with modal amplitudes of coupled linear bending-inplane modes. The linear bending-inplane coupling is due to the shell curvature as well as unsymmetric lamination stacking. Multiple modes, inplane inertia, and the first-order transverse shear deformation for composites are considered in the formulation. A triangular shallow shell finite element is developed from an extension of the triangular …

Hypersonic Boundary-Layer Stability Across A Compression Corner, Hongwu Zhao

Mechanical & Aerospace Engineering Theses & Dissertations

Stability of a hypersonic boundary-layer over a compression corner was investigated numerically. The three-dimensional compressible Navier-Stokes equations were solved using a fifth-order weighted essentially non-oscillating (ArENO) shock capturing scheme to study the shock wave and boundary-layer interactions. The boundary-layer stability was studied in three distinct regions: upstream of the separation region, inside the separation region and downstream of the separation region. After the mean flow field was computed, linear stability theory was employed to predict the unstable disturbance modes in different flow regions and also to find the most amplified disturbance frequency across the compression corner. Gortler instability computations were …

Optimization-Based Architecture For Managing Complex Integrated Product Development Projects, Hisham Mohamed El-Sayed Abdelsalam

Mechanical & Aerospace Engineering Theses & Dissertations

By the mid-1990's, the importance of early introduction of new products to both market share and profitability became fully understood. Thus, reducing product time-to-market became an essential requirement for continuous competition. Integrated Product Development (IPD) is a holistic approach that helps to overcome problems that arise in a complex product development project. IPD emphasis is to provide a framework for an effective planning and managing of engineering projects. Coupled with the fact that about 70% of the life cycle cost of a product is committed at early design phases, the motivation for developing and implementing more effective methodologies for managing …

A Statistical Evaluation Of Risk Priority Numbers In Failure Modes And Effects Analysis Applied To The Prediction Of Complex Systems, Anthony W. Dean

Engineering Management & Systems Engineering Theses & Dissertations

Complex systems such as military aircraft and naval ships are difficult to cost effectively maintain. Frequently, large-scale maintenance of complex systems (i.e., a naval vessel) is based on the reduction of the system to its base subcomponents and the use of manufacturer-suggested, time-directed, preventative maintenance, which is augmented during the systems lifecycle with predictive maintenance which assesses the system's ability to perform its mission objectives. While preventative maintenance under certain conditions can increase reliability, preventative maintenance systems are often costly, increase down time, and allow for maintenance-induced failures, which may decrease the reliability of the system (Ebeling, 1997). This maintenance …

Calibrating Expert Assessments Of Advanced Aerospace Technology Adoption Impact, Bruce A. Conway

Engineering Management & Systems Engineering Theses & Dissertations

This dissertation describes the development of expert judgment calibration methodology as part of elicitation of the expert judgments to assist in the task of quantifying parameter uncertainty for proposed new aerospace vehicles. From previous work, it has been shown that experts in the field of aerospace systems design and development can provide valuable input into the sizing and conceptual design of future space launch vehicles employing advanced technology. In particular (and of specific interest in this case), assessment of operations and support cost implications of adopting proposed new technology is frequently asked of the experts. Often the input consisting of …

Information System Product Development By Integration Of Kano's Customer Satisfaction Model With Quality Function Deployment, Afife Yesim Sireli

Engineering Management & Systems Engineering Theses & Dissertations

Product development of complex, innovative information technology related systems presents difficult challenges for technology managers, and new product failures are a significant problem. The main reason for this is insufficient decision-making due to the lack of a customer-oriented product development process in the information system (IS) companies, which is often related to deficiencies in cooperation between R&D and marketing departments. Integrating consumer requirements into the product design phase is an important factor for improving market success. Therefore, a product development decision model is needed for the managers of information system companies to make more accurate decisions about the characteristics of …

Evolution Of The Band Structure Of Β-In2 S3−3x O3x Buffer Layer With Its Oxygen Content, N. Barreau, S. Marsillac, J. C. Bernède, L. Assmann

Electrical & Computer Engineering Faculty Publications

The evolution of the band structure of β-In2 S3−3x O3x (BISO) thin films grown by physical vapor deposition, with composition x, is investigated using x-ray photoelectron spectroscopy. It is shown that the energy difference between the valence-band level and the Fermi level remains nearly constant as the optical band gap of the films increases. As a consequence, the difference between the conduction band level and the Fermi level increases as much as the optical band gap of the films. The calculation of the electronic affinity [ ] of the BISO thin films shows that it decreases linearly from 4.65 …

The Effects Of Intense Submicrosecond Electrical Pulses On Cells, Jingdong Deng, Karl H. Schoenbach, E. Stephen Buescher, Pamela S. Hair, Paula M. Fox, Stephen J. Beebe

Bioelectrics Publications

A simple electrical model for living cells predicts an increasing probability for electric field interactions with intracellular substructures of both prokaryotic and eukaryotic cells when the electric pulse duration is reduced into the submicrosecond range. The validity of this hypothesis was verified experimentally by applying electrical pulses (durations 100 μs– 60 ns, electric field intensities 3–150 kV/cm) to Jurkat cells suspended in physiologic buffer containing propidium iodide. Effects on Jurkat cells were assessed by means of temporally resolved fluorescence and light microscopy. For the longest applied pulses, immediate uptake of propidium iodide occurred consistent with electroporation as the cause of …

Use Of Eps-Filled Tires As Lightweight Construction Material, Sethapong Sethabouppha

Civil & Environmental Engineering Theses & Dissertations

The purpose of this research is to study the possibility of recycling discarded automobile tires as a lightweight construction material by injecting expanded polystyrene (EPS) into the hollow space of the tires. The observation from compression tests on used tires revealed that the tread wall of these tires bent toward their own center. This inward deformation should provide confining stress to the contained EPS, and thus the compressive strength of EPS-tire composite was expected to be higher than that of EPS.

To produce EPS-filled tire prototypes for this study, EPS type II, with density of 24 kg/m3, was injected into …

Implementation And Testing Of Unsteady Reynolds-Averaged Navier-Stokes And Detached Eddy Simulation Using An Implicit Unstructured Multigrid Scheme, Juan A. Palaez

Mechanical & Aerospace Engineering Theses & Dissertations

Investigation and development of the Detached Eddy Simulation (DES) technique for the computation of unsteady flows on unstructured grids are presented. The motivation of the research work is driven by the ultimate goal of predicting separated flows of aerodynamic importance, such as massive stall or flows over complex non-streamlined geometries. These cases, in which large regions of massively separated flow are present, represent a challenge for conventional Unsteady Reynolds-Averaged Navier-Stokes (URANS) models, that in many cases, cannot produce solutions accurate enough and/or fast enough for industrial design and applications. A Detached Eddy Simulation model is implemented and its performance compared …

Numerical Studies On Supersonic Mixing And Combustion Phenomena, Tarek M. Abdel-Salam

Mechanical & Aerospace Engineering Theses & Dissertations

A numerical study is conducted to investigate the mixing, combustion, and flow characteristics of different scramjet-combustor configurations. Three-dimensional models for the combustors have been used. Numerical results are obtained using a finite volume computational fluid dynamics (CFD) code with unstructured grids with sizes between 200,000 and 400,000 cells.

In the first part of the current study, the effects of the side angle of the fuel injectors in both mixing and combustion processes are investigated. Raised (compression) and relieved (expansion) wall-mounted ramps are used with side angles of 0 (unswept), 5, and 10 degrees. Results are obtained for nonreacting flows as …

Two Dimensional Numerical Simulation Of Highly-Strained Hydrogen-Air Opposed Jet Laminar Diffusion Flames, Kyu C. Hwang

Mechanical & Aerospace Engineering Theses & Dissertations

In this study, a detailed 2-D numerical technique is utilized to investigate the structure, and flame extinction and restoration characteristics of laminar hydrogen-air opposed jet diffusion flames, using both plug (uniform) and parabolic inflow boundary conditions for 3 millimeter jet tubes, spaced 6 millimeters apart and imbedded in low velocity coflows.

First, by using the most recent of two chemical kinetic models, excellent agreement was obtained between calculated distributions of temperature and major species, and published UV laser Raman scattering measurements, for 50% and 100% hydrogen-air flames over a range of input strain rates. Agreement with measured OH profiles was …

Fuzzy System Identification Based Upon A Novel Approach To Nonlinear Optimization, Raymond Scott Starsman

Electrical & Computer Engineering Theses & Dissertations

Fuzzy systems are often used to model the behavior of nonlinear dynamical systems in process control industries because the model is linguistic in nature, uses a natural-language rule set, and because they can be included in control laws that meet the design goals. However, because the rigorous study of fuzzy logic is relatively recent, there is a shortage of well-defined and understood mechanisms for the design of a fuzzy system. One of the greatest challenges in fuzzy modeling is to determine a suitable structure, parameters, and rules that minimize an appropriately chosen error between the fuzzy system, a mathematical model, …

Dynamics Of Phase Transitions On Low-Index Metal Surfaces, Bo Lin

Electrical & Computer Engineering Theses & Dissertations

The surface superheating and phase transitions at the low-index surface of metal were investigated using conventional continuous and 100-ps time-resolved reflection high-energy electron diffraction. Three metal surfaces, In(111), Au(110) and Pb(111), have been investigated in this work. The high temperature behavior of the In(111) surface was investigated using reflection high-energy electron diffraction with 100-ps temporal resolution. The change of surface vacancy density on In(111) is observed from 300 K to near the bulk melting point. The vacancy-formation energy of In(111) surface is estimated from experimental results. The surface vacancy density is observed to increase with temperature; however, the average random …

Field Emission Based Sensors Using Carbon Nanotubes, Changkun Dong

Physics Theses & Dissertations

A number of sensitive applications would be greatly benefited by the development of better cold cathodes that employ the electron field emission process. Among the many kinds of field emitters that could be tried, carbon nanotubes (CNT) have a number of distinct advantages because of their unique geometrical structure, chemical inertness, mechanical stiffness, and high thermal and electrical conductivities. This dissertation describes research in which CNT cathodes were fabricated and their emission characteristics were measured.

Multi-walled carbon nanotubes (MWNT) were grown by chemical vapor deposition (CVD) on various substrates: Ni and Hastelloy gauze, 304 stainless steel (SS) plates, and Ni-coated …

Performing Interactively A Thermo-Fluids Laboratory Experiment In The Virtual Domain, Sushil K. Chaturvedi, Ali O. Akan, Tarek M. Abdel-Salam, A. Priyadershini

Mechanical & Aerospace Engineering Faculty Publications

This paper deals with the development of an experiment in the virtual domain for the undergraduate thermo-fluids laboratory in the mechanical engineering program. A physical experiment titled "Venturimeter as a Flow Measuring Device" is replicated as a computer-based experiment as part of the ongoing effort at Old Dominion University to develop web-based laboratories that would provide students hands-on experience in the virtual domain. A web-based module is developed that allows experimentation and data taking in a virtual setting much like in the physical experiment. This module incorporating the virtual venturimeter has been used by students to take data for several …

Report On The Third Acm/Ieee Joint Conference On Digital Libraries (Jcdl), Michael L. Nelson

Computer Science Faculty Publications

The Third ACM/IEEE Joint Conference on Digital Libraries (JCDL 2003) was held on the campus of Rice University in Houston, Texas, May 27 - 31. Regarding the merging of the ACM and IEEE conference series, in the JCDL 2002 conference report published last year in D-Lib Magazine Edie Rasmussen noted, "Perhaps by next year...no one will remember that it wasn't always so" [1]. Judging by the number of participants I met who did not know that the ACM and IEEE used to hold separate digital library conferences, Rasmussen's prediction has come to pass.

Numerical Techniques For Excitation And Analysis Of Defect Modes In Photonic Crystals, Shangping Guo, Sacharia Albin

Electrical & Computer Engineering Faculty Publications

Two numerical techniques for analysis of defect modes in photonic crystals are presented. Based on the finite-difference time-domain method (FDTD), we use plane wave incidences and point sources for excitation and analysis. Using a total-field/scattered-field scheme, an ideal plane wave incident at different angles is implemented; defect modes are selectively excited and mode symmetries are probed. All modes can be excited by an incident plane wave along a non-symmetric direction of the crystal. Degenerate modes can also be differentiated using this method. A proper arrangement of point sources with positive and negative amplitudes in the cavity flexibly excites any chosen …

Common Data Administration, Data Management, And Data Alignment As A Necessary Requirement For Coupling C4isr Systems And M&S Systems, Andreas Tolk

Computational Modeling & Simulation Engineering Faculty Publications

Within the application domain of military simulation systems, training and exercises as well as support to real operations require the coupling of the simulation system delivering the needed functionality with the Command, Control, Computing, Communications, Intelligence, Surveillance, and Reconnaissance (C4ISR) system providing the necessary data. The solution to this challenge is to build appropriate interfaces. Although in long term a more integrated approach will be necessary, in short and mid term, gateways and interfaces are likely to remain the standard. However, in order to succeed with the respective efforts, at least on the data level of interoperability, a common solution …

Jsb Composability And Web Services Interoperability Via Extensible Modeling & Simulation Framework (Xmsf), Model Driven Architecture (Mda), Component Repositories, And Web-Based Visualization, Don Brutzman, Andreas Tolk

Computational Modeling & Simulation Engineering Faculty Publications

"Study Report prepared for the U. S. Air Force, Joint Synthetic Battlespace Analysis of Technical Approaches (ATA) Studies & Prototyping"

Overview: This paper summarizes research work conducted by organizations concerned with interoperable distributed information technology (IT) applications, in particular the Naval Postgraduate School (NPS) and Old Dominion University (ODU). Although the application focus is distributed modeling & simulation (M&S) the results and findings are in general easily applicable to other distributed concepts as well, in particular the support of operations by M&S applications, such as distributed mission operations. The core idea of this work is to show the necessity of …

Anisotropy And Its Relation To Liquefaction Resistance Of Granular Material, Isao Ishibashi, Omer F. Capar

Civil & Environmental Engineering Faculty Publications

This research establishes quantitative relationships between soil's anisotropy and liquefaction resistance for granular materials. Uniform medium density (D_r = 50%) sand specimens were prepared using three different sample preparation techniques (air pluviated (AP), moist tamped (NIT), and moist vibrated (MV)) to create different initial soil fabrics. Undrained cyclic triaxial tests were then performed to determine the liquefaction resistance of each soil specimen. On the same specimens in the triaxial cell, vertical and horizontal compression wave velocities and vertical shear wave velocity (V_s) were measured using piezoelectric bender elements. Anisotropic (transversely isotropic) elastic constants of the soil specimens were …

An Air-Filter Sensor For Home-Used Air Conditioners, Cheng Y. Lin, Gary R. Crossman, Alok K. Verma

Engineering Technology Faculty Publications

This paper presents a successful senior project of instrumentation developed in a Mechanical Engineering Technology senior capstone course. Students were encouraged to approach the problem of designing an air-filter sensor and to propose an optimum and practical solution for the problem. Work includes conceptual design and analysis, implementation, tests and modifications. When an air filter is used in a home air conditioner, inhabitants often forget when to replace it until the cooling or heating capacity is obviously reduced. If the filter remains in service, the efficiency of the cooling/heating system will continue decreasing while the electricity bill will significantly increase. …

Protocols For Disease Classification From Mass Spectrometry Data, Michael Wagner, Dayanand Naik, Alex Pothen

Mathematics & Statistics Faculty Publications

We report our results in classifying protein matrix-assisted laser desorption/ionizationtime of flight mass spectra obtained from serum samples into diseased and healthy groups. We discuss in detail five of the steps in preprocessing the mass spectral data for biomarker discovery, as well as our criterion for choosing a small set of peaks for classifying the samples. Cross-validation studies with four selected proteins yielded misclassification rates in the 10-15% range for all the classification methods. Three of these proteins or protein fragments are down-regulated and one up-regulated in lung cancer, the disease under consideration in this data set. When cross-validation studies …

Academic Fleet Renewal- Two Years Later, Larry Atkinson

CCPO Publications

(First paragraph) In November 2000, I wrote a Soapbox article on fleet renewal for Sea Technology. It is a little unsettling to see how slowly ideas move towards implementation. Nevertheless, we are making progress. In this editorial I will note a bit of that progress and try to guess where we will be in two more years.

Simple Plane Wave Implementation For Photonic Crystal Calculations, Shangping Guo, Sacharia Albin

Electrical & Computer Engineering Faculty Publications

A simple implementation of plane wave method is presented for modeling photonic crystals with arbitrary shaped ‘atoms’. The Fourier transform for a single ‘atom’ is first calculated either by analytical Fourier transform or numerical FFT, then the shift property is used to obtain the Fourier transform for any arbitrary supercell consisting of a finite number of ‘atoms’. To ensure accurate results, generally, two iterating processes including the plane wave iteration and grid resolution iteration must converge. Analysis shows that using analytical Fourier transform when available can improve accuracy and avoid the grid resolution iteration. It converges to the accurate results …

Plasma Interaction With Microbes, M. Laroussi, D. A. Mendis, M. Rosenberg

Electrical & Computer Engineering Faculty Publications

The germicidal effects of a non-equilibrium atmospheric pressure plasma generated by a novel resistive barrier discharge on representatives of the two classes of bacteria (Gram-negative and Gram-positive) are discussed. The plasma exposure, while being lethal to both bacterial classes, also produced gross structural damage in the Gram-negative E. coli while none was observed in the more structurally robust Gram-positive Bacillus subtilis. An electrophysical process involving the role of the electrostatic tension on a charged body in a plasma is invoked to explain both observations. Since the efficacy of this electrophysical process depends not only on the tensile strength of …

Study Of A Growth Instability Of Γ-In[Sub 2]Se[Sub 3], C. Amory, J. C. Bernede, S. Marsillac

Electrical & Computer Engineering Faculty Publications

γ-In[sub 2]Se[sub 3] thin film are deposited for various substrate temperatures in the range of 523–673 K. This study shows that at 573 and 673 K the thin films are well crystallized with grains aligned along the c axis. Between these temperatures, a domain of instability appears where the γ-In[sub 2]Se[sub 3] thin films have a randomly orientation and the c-lattice parameter increases. The presence of the metastable phase κ-In[sub 2]Se[sub 3], during the growth, can explain the existence of this domain of instability. The insertion of Zn during the preparation process allows us to stabilize the phase κ at …