Engineering Commons^™

Non-Linear Finite Element Analysis And Optimization For Light Weight Design Of An Automotive Seat Backrest, Prasanna Balaji Thiyagarajan

All Theses

ABSTRACT
With the goal of reduced weight, free-size finite element based optimization with constraints on stresses and displacements of a commercially available automotive seat backrest frame manufactured from several stamped and welded low carbon ductile steel sheets is performed using OptiStruct linear optimization package from Altair under the loading requirements of mandatory ECE R-17 backrest-moment test and headrest test for vehicles sold in Europe. In the free-size optimization, sheet metal thickness in a finite element shell model of the backrest frame are design variables with stress and displacement limits as the constraints, with an objective to minimize mass. Using the …

Thermal And Structual Properties Of Candidate Moldable Glass Types, Scott Gaylord

All Theses

This thesis contains results of our efforts to develop a method for defining key glass material properties that must be known and modeled for the design and experimental validation of a precision glass molding (PGM) process for optical glasses. Viscosity, calorimetric, and thermal expansion properties of two commercial glass types N-BK7 and P-SK57 of SCHOTT were characterized to establish a proof-of-concept protocol for the experimental determination of meaningful material properties. Experimental results were determined in order to be incorporated into a computational model predicting final glass size and shape following a molding cycle. Experimental methods were confirmed on the two …

Preliminary Study On Optimization Of Data Distribution In Resource Sharing Systems, Grzegorz Chmaj, Krzysztof Walkowiak

Electrical & Computer Engineering Faculty Research

Grid structures are increasingly considered as very convergent with peer-to-peer networks. This paper presents a model of network acting both as grid and peer-to-peer network, used for data computation and distribution. Presented PPLC algorithm is a complete solution for both grid and peer-to-peer points of view. Problem formulation is presented, as well as solution heuristic algorithm and research results.

Cues For Cellular Assembly Of Vascular Elastin Networks, Chandrasekhar Kothapalli

All Dissertations

Elastin, a structural protein distributed in the extracellular matrix of vascular tissues is critical to the maintenance of vascular mechanics, besides regulation of cell-signaling pathways involved in injury response and morphogenesis. Thus, congenital absence or disease-mediated degradation of vascular elastin and its malformation within native vessels due to innately poor elastin synthesis by adult vascular cells compromise vascular homeostasis. Current elastin regenerative strategies using tissue engineering principles are limited by the progressive destabilization of tropoelastin mRNA expression in adult vascular cells and the unavailability of scaffolds that can provide cellular cues necessary to up-regulate elastin synthesis and regenerate faithful mimics …

Inferring Mechanical Resonances In Micro - And Nanocantilevers Using The Harmonic Detection Of Resonance (Hdr) Method To Develop A Novel Sensing Platform, Gayatri Keskar

All Dissertations

During the past two decades, advances in microelectromechanical systems (MEMS) have spurred efforts worldwide to develop sensing platforms based on smart microcantilevers. A microcantilever beam is one of the simplest MEMS structures which forms the basis for portable, fast and highly sensitive schemes that are capable of measuring small deflections in static or dynamic response due to changes in external parameters such as mass, pressure, charge, etc.
In this dissertation, I mainly focus on MEMS sensors with transducers in the form of microcantilevers. Variations in the microcantilever's response such as resonant frequency, amplitude, phase and quality factor when exposed to …

Kinetics Of Preferential Adsorption And Equilibrium Properties Of Interfacial Layers Formed From Polymer Chains That Tether By Multiple Ends, Jose Alonzo Calderon

All Dissertations

Due to their ability to straddle phase boundaries, polymer brushes represent a model system for studies of polymer-modified surfaces. The research presented in this dissertation focuses on understanding a special type of polymer brushes formed at the solid-fluid interface by self-assembly of block copolymer chains that have the ability to tether by multiple ends, thus creating loops on the surface. Specifically, I study the self-assembly of a series of poly(2-vinylpyridine)-polystyrene-poly(2-vinylpyridine) (PVP-b-PS-b-PVP) triblock copolymers and PVP-b-PS star block copolymers adsorbed from the selective solvent toluene onto silicon and mica surfaces. The triblock and star copolymers have different molecular weights and PS/PVP …

Performance Based Decisions Under Uncertainty And Risk, Sundeep Samson

All Dissertations

Decision making has became increasingly complex as risky decisions are made in uncertain environments. To minimize risk, the problem of quantifying risk becomes very significant. In our review of the literature, we found a number of different risk measures. A closer study reveals that most of these risk measures define both risk and uncertainty in many different ways.
In this dissertation, we model uncertainty and risk based on the Knightian definition of uncertainty and risk. We propose this alternative modeling paradigm and introduce our decision making methodology by solving an illustrative problem presented by a group of decision makers from …

Revenue And Order Management Under Demand Uncertainty, Kiran Chahar

All Dissertations

We consider a firm that delivers its products across several customers or markets, each with unique revenue and uncertain demand size for a single selling season. Given that the firm experiences a long procurement lead time, the firm must decide, far in advance of the selling season not only the markets to be pursued but also the procurement quantity. In this dissertation, we present several operational scenarios in which the firm must decide which customer demands to satisfy, at what level to satisfy each customer demand, and how much to produce (or order) in total.
Traditionally, a newsvendor approach to …

Similarity Metrics Applied To Graph Based Design Model Authoring, Srinivasan Anandan

All Dissertations

Model reuse is typically facilitated by search and retrieval tools, matching the sought model with models in a database. This research aims at providing similar assistance to users authoring design exemplars, a data structure to represent parametric and geometric design problems. The design exemplar represents design problems in the form of a bi-partite graph consisting of entities and relations. Authoring design exemplars for relatively complex design problems can be time consuming and error prone. This forms the motivation of developing a search and retrieval tool, capable of retrieving exemplars that are similar to the exemplar that a user is trying …

High Temperature Wetting And Multilayer Adsorption In Oxide Systems, Haijun Qian

All Dissertations

The primary objective of this thesis research is to greatly advance the knowledge of the formation mechanism and thermodynamic stability of a unique class of surficial amorphous films (SAFs) and analogous intergranular films (IGFs) via critical experiments and modeling. These quasi-liquid IGFs and SAFs films exhibit the following distinct characteristics: 1) self-regulating (equilibrium) thicknesses on the order of 1 nm, 2) structures and compositions that are neither found nor stable as bulk phases, and 3) thermodynamic stability below the bulk solidus lines.
The first part of this study examines anisotropic wetting of ZnO single crystals by Bi2O3-rich liquid with and …

Some Problems In Statistical Mechanics With Applications To Materials Science, Ethan Ballard

All Dissertations

In this work, some problems in statistical mechanics related to condensed matter physics and of general interst in materials science, physics, chemistry and polymer science are considered. In chapters 1-4, the work by E.M. Lifshitz on the group-theoretical refinements of the Landau theory of phase transitions is brought to completion. Based on mathematical results obtained by Yamabe, Osgood, Phillips, Sarnak, and Kholodenko analytical results for determinants were developed which allows for prediction of the symmetry of the phase after a phase transition provided that the symmetry prior to the phase transition is known. Numerical results are presented which are in …

Chitosan Derivatives For Tissue Engineering, Yongzhi Qiu

All Dissertations

Chitosan, a naturally occurring polysaccharide, and its derivatives have been widely explored for biomedical applications due to their biocompatibility and biodegradability. In our studies, we developed a series of chitosan derivatives through chemical modifications. These chitosan derivatives not only possess better processibility in scaffolds fabrication, but also show excellent potentials in tissue engineering applications, including blood vessel and bone tissue engineering.
The excellent antithrombogenic property is crucial for vascular engineering applications, especially in engineering small-diameter blood vessels. In our studies, chitosan was chemically modified by phthalization and the phthalized chitosan exhibited great antithrombogenic property. Through a wet- phase-inversion process, tubular …

The Effects Of Crumb Rubber Particles On Highway Noise Reduction - A Laboratory Study, Khaldoun Shatanawi

All Dissertations

Traffic noise is a major setback to the life quality of residents living in the vicinity of highways. Over the past 40 years, much legislation has been passed to regulate sound levels to which residents are exposed. Among the many approaches adopted to alleviate the problem, crumb rubber modified asphalt has been proposed as a measure to reduce highway traffic noise.
The use of crumb rubber modified asphalt to reduce traffic noise on pavements had not been evaluated in great detail prior to this study. This research investigates the effects of crumb rubber particles on asphalt pavement noise absorption ability. …

A Comprehensive Multiphysics, Multiscale Modeling Framework For Carbon Nanotube Fabrication Process By Chemical Vapor Deposition, Mahmoud Reza Hosseini

All Dissertations

Carbon nanotubes (CNTs) are among the most promising nanosize materials as evidenced by the attention they have received since their discovery in 1991 and a wide range of scientific and industrial applications. Each of these applications requires unique CNTs with specific length, diameter and chirality. However, control of these parameters is considered as one of the main challenges for large scale production of CNTs. Furthermore, these processes are not well designed so as to limit the number of CNT defect sites or the production of unwanted byproducts such as amorphous carbon. Therefore, it is crucial to develop a controlled CNTs …

The Spaceflight Environment And The Skeletal System, Eric Bandstra

All Dissertations

The spaceflight environment presents many challenges to the human body. Bone loss in astronauts is a well known consequence of reduced loading in the weightless environment of low-earth orbit. Recent studies have also indicated that spaceflight relevant types of radiation (at relatively high doses) have deleterious effects on trabecular bone. Both of these represent potential skeletal challenges during long-duration spaceflight. The objective of these studies is to examine the response of bone to models of the spaceflight environment.
Astronauts will likely absorb doses of protons and heavy ions during lengthy missions outside the Earth's magnetosphere. Following exposure to a range …

Framework For Probabilistic Analysis Of Recurrent Landslides: A Case Study Of El Berrinche, Raul Flores

All Dissertations

Assessment of slope stability or landslide is a complex geotechnical problem that involves much uncertainty. To consider combined effects of the uncertainties in soil parameters and changes in pore water pressure, reliability theory may be employed. In this dissertation study, a reliability-based framework for the probabilistic analysis of recurrent landslides is developed.
Generally, the stability of a slope is analyzed deterministically with methods of limit equilibrium and a factor of safety is computed. This approach is referred to as the deterministic approach. However, a deterministic analysis alone may not be sufficient in assessing the risk level of a landslide in …

Aerodynamic Analysis Of A Generic Fighter With A Chine Fuselage/Delta Wing Configuration Using Delayed Detached-Eddy Simulation, Tiger L. Jeans, David R. Mcdaniel, Russell M. Cummings, William H. Mason

Aerospace Engineering

The Modular Transonic Vortex Investigation (MTVI) program at NASA Langley Research Center investigated the transonic characteristics of generic fighter configurations with chined fuselages and delta wings. Previous experiments show that the fuselage and leading edge vortex interactions are detrimental to the vehicle’s aerodynamic characteristics for angles of attack greater than 23º at low angles of sideslip. This is largely due to abrupt asymmetric vortex breakdown, which leads to pronounced pitch-up and significant nonlinearities in lateral stability that could result in roll departure. An improved understanding of the exact origins of this nonlinear behavior would improve future fighter design, and predictive …

Moore, Mary (Taylor) Leiper, 1885-1973 (Sc 1714), Manuscripts & Folklife Archives

Manuscript Collection Finding Aids

Finding aid and scan (Click on "Additional Files" below) for Manuscripts Small Collection 1714. Letter from Mary Leiper Moore, Bowling Green, Kentucky to Ben Johnson, Bardstown, Kentucky, 27 September 1938, related to covered bridges at Bowling Green and Bardstown. Includes copy of an act passed by the Kentucky General Assembly authorizing reconstruction of bridges destroyed by Confederate guerrilla Billy Magruder.

An Evaluation Of Proposed Formula 1 Aerodynamic Regulations Changes Using Computational Fluid Dynamics, Robert L. Perry, David D. Marshall

Aerospace Engineering

This report evaluates the proposed FIA Formula 1 World Championship aerodynamics rules changes intended to increase on track passing for the 2009 season. Two full Formula 1 cars were modeled under close drafting conditions, both under the current regulations and the proposed 2009 regulations to determine whether or not the FIA's goals of reducing down force by 50% and improving sensitivity to leading car wakes would be met. Under the current regulations, a car following another at 2.4 car lengths loses approximately 17% of it down force compared to isolation. The new regulations were counter productive and ineffective, failing both …

A Real-Time Traffic Condition Assessment And Prediction Framework Using Vehicle-Infrastructure Integration (Vii) With Computational Intelligence, Yongchang Ma

All Dissertations

This research developed a real-time traffic condition assessment and prediction framework using Vehicle-Infrastructure Integration (VII) with computational intelligence to improve the existing traffic surveillance system. Due to the prohibited expenses and complexity involved for the field experiment of such a system, this study adopted state-of-the-art simulation tools as an efficient alternative.
This work developed an integrated traffic and communication simulation platform to facilitate the design and evaluation of a wide range of online traffic surveillance and management system in both traffic and communication domain. Using the integrated simulator, the author evaluated the performance of different combination of communication medium and …

Flexural Behavior And Design Of The New Built-Up Litesteel Beams, Sivapathasunderam Jeyaragan, Mahen Mahendran

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

A new cold-formed steel beam, known as the LiteSteel Beam (LSB), has the potential to transform the low-rise building industry. The new beam is effectively a channel section with two rectangular hollow flanges and a slender web, and is manufactured using a simultaneous cold-forming and electric resistance welding process. Built-up LSB sections are expected to improve their flexural capacity and to increase their applications. They are also likely to mitigate the detrimental effects of lateral distortional buckling observed with single LSB members of intermediate spans. However, the behaviour of built-up beams is not well understood. Currently available design rules based …

Innovative Composite Cold Formed Steel Floor Joist System, D. M. Fox, R. M. Schuster, M. Strickland

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Presented in this paper is a new, unique and innovative composite cold formed steel floor system developed by iSPAN Technologies, called the “iSPAN Composite Floor System”. The joist sections are fabricated by fastening two cold-rolled flange chord elements with cold-driven rivets to a flat web element. This makes it possible to create a section where the flange chord elements can be of a different steel thickness with respect to the web element, resulting in a most efficient structural cross section and numerous design alternatives. The joist sections have lip-reinforced web openings spaced at 4 ft o.c. along the joist length …

Experimental And Numerical Studies Of The Shear Behaviour Of Litesteel Beams, P. Keerthan, M. Mahendran

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.

Vibration Performance Of Lightweight Floor Systems Supported By Cold-Formed Steel Joists, B. W. Davis, L. Xu

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

A study investigating dynamic characteristics of full-scale floor systems was performed for several laboratory-constructed and in situ floors. Floors were constructed with cold-formed steel joists and designed for residential mid-rise applications. Typical construction details including span, subfloor, topping, strongback and framing condition were varied, and their influence on fundamental frequency, damping ratio and deflection at mid-span compared. Changes in construction details which significantly increased floor mass, regardless of added stiffness, were found to lower the fundamental frequency. Adding a strongback with restrained ends provided a significant increase in fundamental frequency, stiffness and damping ratio. Laboratory tested floor systems were generally …

Statistical Methods For Polarimetric Imagery, Daniel A. Lemaster

Theses and Dissertations

Estimation theory is applied to a physical model of incoherent polarized light to address problems in polarimetric image registration, restoration, and analysis for electro-optical imaging systems. In the image registration case, the Cramer-Rao lower bound on unbiased joint estimates of the registration parameters and the underlying scene is derived, simplified using matrix methods, and used to explain the behavior of multi-channel linear polarimetric imagers. In the image restoration case, a polarimetric maximum likelihood blind deconvolution algorithm is derived and tested using laboratory and simulated imagery. Finally, a principal components analysis is derived for polarization imaging systems. This analysis expands upon …

Contingency Analysis Using Synchrophasor Measurements, Megan Vutsinas

All Theses

The rapid progress of synchrophasor technology greatly promotes many applications of wide-area measurement systems. Traditionally, contingency analysis is based on off-line studies conducted long in advance. This is becoming increasingly unreliable for real-time operations. New technologies, which rely on accurate, high resolution, and real-time monitoring of actual system conditions using phasor measurements are needed to support the real-time operations. In this research an algorithm is developed, using phasor measurements, that allows real-time analysis and correction of contingencies in power systems. The focus is specifically on overloaded lines. An off-line study performed with POWERWORLD software is used for contingency analysis, and …

Tooth Engagement Evaluation Of Involute Spline Couplings, Robert R. Robins

Theses and Dissertations

Spline couplings are used in applications involving high torque; however, due to variations in teeth clearances, all teeth in spline couplings do not engage simultaneously, causing some of the teeth to carry a disproportionately large portion of the total load. Variations in tooth-to-tooth clearances mean the first pair of teeth to engage will carry more load and fail sooner. This has lead to an industry practice of designing splines around the criteria that only 25-50% of the teeth on a spline coupling will engage and carry the load, and the load is generally assumed to be uniformly distributed. This research …

Role Of Food Neophobia, Food Attitudes And Written Information On The Acceptance Of Novel Fish Products : A Cross-Cultural Study, Koei Kudo

Dissertations and Theses

The present research used an integrative and multi-disciplinary approach to investigate the relations among food attitudes, food neophobia and acceptance of novel and familiar albacore tuna dishes for Japanese and U.S. consumers.

A pilot study selected seasonings and cooking methods that were familiar or novel to each culture, and identified the most relevant health benefits of omega-3 fatty acids (FA).

The main study employed a self-reported, web-based questionnaire where back-translation maximized the cross-cultural equivalency of US and Japanese versions. Scales of food neophobia (Crystallized Neophobia Scale, or CNS) and attitudes towards foods (Health-, Pleasure- and Convenience-Oriented Food Attitudes Scale, or …

Ceas E-News 08.12.2008, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

Sunseeker team wins sportsmanship award and more at 2008 NASC

High-Impact, Energy-Absorbing Vehicle Barrier System : United States Patent 7,410,320 B2, Ronald K. Faller, Dean L. Sicking, John R. Rohde, John D. Reid, Robert W. Bielenberg, James C. Holloway, Karla A. Polivka

Department of Mechanical and Materials Engineering: Faculty Publications

A high-impact, energy-absorbing vehicle barrier system generally includes a substantially rigid outer containment wall coupled via strap assemblies with an energy-absorbing inner impact wall, and energy-absorbing cartridges strategically positioned between the impact wall and containment wall. The impact wall is constructed of a number of tubes coupled with one another to present a substantially smooth, unifonn surface to passing vehicles. The energy-absorbing cartridges generally consist of a foam member or a number of foam sheets which compress and crush between the containment wall and impact wall to absorb energy from an errant vehicle striking the face of the impact wall, …