Engineering Commons^™

Greenhouse Gas Emissions Inventory Of The Centalized Renewable Energy System (Cres) At Nebraska Innovation Campus, Matan Gill, Adam Liska

Adam Liska Papers

The Centralized Renewable Energy System (CRES) at Nebraska Innovation Campus (NIC) is a heat-exchanger system that utilizes reclaimed, non-drinkable water from the nearby water treatment plant to heat and cool a projected 1.675 million square feet of office and lab space. A greenhouse gas emissions inventory was estimated for the CRES operating at full build-out of the campus in 2035, compared to conventional office space, being a control system with standard chiller and boiler configuration. The control system is estimated to emit 30,787 metric tons of carbon dioxide-equivalent per year (Mg CO₂e yr-1), whereas heating and cooling Nebraska …

Formal Design Concept And Participant Behavior Analysis For Crowdsourcing Design, Jihoon Kim

Wayne State University Dissertations

Crowdsourcing has emerged as a new design resource for conceptual design process and multiple crowdsourcing services provide an opportunity for design idea collection and concept generation by crowds. However, few formal methods are available to extract and evaluate design concepts from the activities of the design crowd. Scarcity of information and non-guaranteed quality of contributions are often challenges to be tackled. To overcome the challenges, the research aims to answer how a system systematically extracts and represents the explicit or implicit hidden design concepts from crowdsourcing design activities and how crowdsourcing design activities of participants are captured as design information …

A Prediction Modeling Framework For Noisy Welding Quality Data, Junheung Park

Wayne State University Dissertations

Numerous and various research projects have been conducted to utilize historical manufacturing process data in product design. These manufacturing process data often contain data inconsistencies, and it causes challenges in extracting useful information from the data. In resistance spot welding (RSW), data inconsistency is a well-known issue. In general, such inconsistent data are treated as noise data and removed from the original dataset before conducting analyses or constructing prediction models. This may not be desirable for every design and manufacturing applications since every data can contain important information to further explain the process. In this research, we propose a prediction …

Biases In Thorpe-Scale Estimates Of Turbulence Dissipation. Part I: Assessments From Large-Scale Overturns In Oceanographic Data, Benjamin D. Mater, Subhas K. Venayagamoorthy, Louis St Laurent, James N. Moum

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Oceanic density overturns are commonly used to parameterize the dissipation rate of turbulent kinetic energy. This method assumes a linear scaling between the Thorpe length scale LT and the Ozmidov length scale LO. Historic evidence supporting LTLO has been shown for relatively weak shear-driven turbulence of the thermocline; however, little support for the method exists in regions of turbulence driven by the convective collapse of topographically influenced overturns that are large by open-ocean standards. This study presents a direct comparison of LT and LO, using vertical profiles of temperature and microstructure shear collected in the Luzon Strait-a site characterized by …

Comparisons Of Horizontal-Axis Wind Turbine Wake Interaction Models, Jordan M. Wilson, Cole J. Davis, Subhas K. Venayagamoorthy, Paul R. Heyliger

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this study, Reynolds-averaged Navier-Stokes (RANS) simulations are performed using the k-ϵ and k-ω shear stress transport (SST) turbulence closure schemes to investigate the interactions of horizontal-axis wind turbine (HAWT) models in the neutrally stratified atmospheric boundary layer (ABL). A comparative study of actuator disk, actuator line, and full rotor models of the National Renewable Energy Laboratory (NREL) 5 MW reference turbine is presented. The open-source computational fluid dynamics (CFD) code open foam 2.1.0 and the commercial software ANSYS fluent 13.0 are used for simulations. Single turbine models are analyzed for turbulent structures and wake resolution in the downstream region. …

The Formation And Fate Of Internal Waves In The South China Sea, Matthew H. Alford, Thomas Peacock, Jennifer A. Mackinnon, Jonathan D. Nash, Maarten C. Buijsman, Luca A. Centurioni, Shenn-Yu Chao, Ming-Huei Chang, David M. Farmer, Oliver B. Fringer, Ke-Hsien Fu, Patrick C. Gallacher, Hans C. Graber, Karl R. Helfrich, Steven M. Jachec, Christopher R. Jackson, Jody M. Klymak, Dong S. Ko, Sen Jan, T. M. Shaun Johnson, Sonya Legg, I-Huan Lee, Ren-Chih Lien, Matthew J. Mercier, James N. Mourn, Ruth Musgrave, Jae-Hun Park, Andrew I. Pickering, Robert Pinkel, Luc Rainville, Steven R. Ramp, Daniel L. Rudnick, Sutanu Sarkar, Alberto Scotti, Harper L. Simmons, Louis C. St. Laurent, Subhas Karan Venayagamoorthy, Yu-Huai Wang, Joe Wang, Ying J. Yang, Theresa Paluszkiewicz, Tswen-Yung David Tang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Internal gravity waves, the subsurface analogue of the familiar surface gravity waves that break on beaches, are ubiquitous in the ocean. Because of their strong vertical and horizontal currents, and the turbulent mixing caused by their breaking, they affect a panoply of ocean processes, such as the supply of nutrients for photosynthesis¹, sediment and pollutant transport² and acoustic transmission³; they also pose hazards for man-made structures in the ocean⁴. Generated primarily by the wind and the tides, internal waves can travel thousands of kilometers from their sources before breaking⁵, making it …

Higher Education: Opinions And Participation Among Nonmetropolitan Nebraskans: 2015 Nebraska Rural Poll Results, Rebecca J. Vogt, Cheryl A. Burkhart-Kriesel, Randolph L. Cantrell, Bradley Lubben, L. J. Mcelravy

Rural Futures Institute: Publications

Includes

Executive Summary

Introduction

Education or Training Taken

Participation in Education or Training Activities during Past Two Years

Types of Education or Training Taken in Past Two Years

Satisfaction with Types of Education or Training

Satisfaction with Types of Education or Training

Opinions about Education

A Collaborative Adaptive Wiener Filter For Image Restoration Using A Spatial-Domain Multi-Patch Correlation Model, Khaled M. Mohamed, Russell C. Hardie

Electrical and Computer Engineering Faculty Publications

We present a new patch-based image restoration algorithm using an adaptive Wiener filter (AWF) with a novel spatial-domain multi-patch correlation model. The new filter structure is referred to as a collaborative adaptive Wiener filter (CAWF). The CAWF employs a finite size moving window. At each position, the current observation window represents the reference patch. We identify the most similar patches in the image within a given search window about the reference patch. A single-stage weighted sum of all of the pixels in the similar patches is used to estimate the center pixel in the reference patch. The weights are based …

Enhanced Mechanical Stability Of Interlayer Dielectrics With Self-Organized Molecular Pores, Akanksha Pandey

Material Science and Engineering Theses - Archive

In order to reduce resistance-capacitance delays in interconnect structures, ultralow-k films are used as interlayer dielectric materials. In most cases the preferred method to achieve the lower dielectric constant is the use of porous carbon doped silicon oxide (p-SiCOH) dielectrics. A downside of porosity in a dielectric layer during device fabrication is that it reduces the mechanical reliability of the dielectric and increases the susceptibility to adsorption of damaging materials. To overcome this and produce a material which can sustain the rigorous processes of fabrication, it is necessary to optimize the mechanical, thermal and chemical properties along with the electrical …

Enhanced Photocatalytic Performance Of Titania Nanobelts Decorated With Gold Particles Synthesized Using Stirring-Assisted Hydrothermal Method, Yi Shen

Material Science and Engineering Theses - Archive

In this thesis, anatase TiO2 nanobelts (TNBs) have been successfully obtained via an optimized stirring-assisted hydrothermal synthesis. The impact of stirring speed has been studied. Difference in morphology caused by stirring speed was observed by high resolution Field-Emission SEM (FE-SEM). Methylene Blue degradation test indicated that at certain stirring speed, i.e., 700 rpm, which was the highest, produced the best photoactivity than commercial P25 TiO2.Furthermore, Au decorated TNBs were obtained by a simple reduction reaction with Au-containing precursor. The Au-TNBs were founded to outperform in MB degradation the commercial P25 TiO2 and the pristine TNBs under both UV and visible …

Three-Dimensional Indeterminate Impacts In Legged Robotic Locomotion, Abhishek Chatterjee

Mechanical and Aerospace Engineering Theses - Archive

Legged robotic systems undergo a large number of impacts during walking or running tasks. These impacts occur over the surface of contact between the feet and the ground. If a rigid body assumption is held, these impacts can be analyzed by selecting a certain number of points on the impacting bodies. A minimum of three points are required for analyzing a surface contact on a plane. However, using a minimum number of points for analyzing surface impact would require an additional analysis for appropriately selecting these points. On the other hand, if a large number of evenly distributed impact points …

Biomechanical Analysis Of The Cornea To Improve Post Surgical Outcomes Through Finite Element Analysis, Salman Nasir Khan

Mechanical and Aerospace Engineering Dissertations - Archive

Vision deterioration is a major healthcare concern. It is estimated that one in three persons develops some form of vision reducing eye disease by the age of 65 and these numbers are expected to increase. Deterioration in visual acuity is due to ocular diseases that change the shape or clarity of the cornea. Health/shape of the cornea is extremely important as it determines the refractive power of the eye.This work studies ocular surgeries from a mechanical/structural engineering perspective. It begins by discussing laser in-situ keratomileusis (LASIK) surgery and explains the role of lasers in modifying the corneal shape to improve …

Design Of Cooling And Ventilation Of Telecommunication Shelter At High Altitude, Palak Patel

Mechanical and Aerospace Engineering Theses - Archive

Telecommunication shelters house information technology (IT), networking, power, and cooling equipment such as racks, power cabinets, batteries, fans, etc. For reliable operation of the IT and networking equipment, shelters need to satisfy or exceed minimum environmental guidelines for all equipment they contain. These guidelines typically contain specified operational temperature, maximum gaseous and particular contaminant levels. In this work, cooling and ventilation needs of a telecommunication shelter at an altitude of 9,678 feet are studied by modeling the system and simulating various operational and weather scenarios using FloVENT 10.1, a computational fluid dynamics (CFD) tool. The shelter contains two compartments: the …

Experimental And Computatonal Analysis Of The Effect Of Pcb Layer Copper Thickness And Prepreg Layer Stiffness On Solder Joint Reliability, Sanjay Mahesan Revathi

Mechanical and Aerospace Engineering Theses - Archive

The emphasis of this study is to find out how the solder joints of the BGA package are affected with change in the stack up PCB layer copper thickness and the prepeg layer stiffness. In general the effect of the PCB layer thickness is to increase the stress and strain range and to decrease the thermal fatigue life. Basically a PCB consists of different layers with different material properties (Eg: Cu, FR4 etc.).In this paper we deal with the PCB with 1-6-1 configuration (6 core layers and 1 prepeg layer on the top and bottom). A Prepeg is a fiber …

Study Of Hotspot Cooling For Integrated Circuits Using Electrowetting On Dielectric Digital Microfluidic System, Govindraj Shreyas Bindiganavale

Mechanical and Aerospace Engineering Dissertations - Archive

Thermal management in electronics is an ever-growing challenge which needs constant innovations to regulate hotspots in integrated circuits for safe operation within its Thermal Design Power (TDP) envelope. As the number of transistors increase due to advancements in photolithography to enable die shrink, portable electronics are on the rise and so is the demand for microscale cooling systems because conventional cooling components like heat sinks, heat pipes and fans are not capable of meeting design requirements for cooling solutions. In addition to the benefits enjoyed by microscale cooling systems like compact and lightweight design along with simple operation, electrowetting on …

Organic/Inorganic Guanidinium-Based Hybrid Anion Exchange Membranes For Alkaline Fuel Cells, Shambhavi Raju Sakri

Material Science and Engineering Theses - Archive

Organic-inorganic hybrid membranes are good alternatives to homogeneous ones to overcome the limitations posed by the individual constituent materials. These membranes pose promising applications in fuel cells with the combination of phenomenal functionality of organic polymers and stability of inorganic material. Introduction of inorganic materials into the polymer matrix is usually known to show an increase in mechanical properties of the membrane while, the organic part of the membrane, i.e., the polymer contributes towards the electrochemical properties. The properties of the individual materials combine to enhance the characteristic properties of the hybrid membranes. In this thesis we attempted to develop …

Accurate Three-Dimensional Characterization Of The Nonlinear Material Constitutive Properties For Laminated Composite Materials, Julia Elaine Cline

Mechanical and Aerospace Engineering Dissertations - Archive

Accurate and efficient full three-dimensional characterization of mechanical properties of composite materials, including stress-strain curves and strength characteristics, is essential for understanding complex deformation and failure mechanisms of composites and optimizing material qualification efforts. Non-contact full-field deformation measurement techniques such as digital image correlation (DIC) allowing for assessment of all surface strain components on the entire specimen surface, enable simpler experimental setups and material specimen designs for more efficient and accurate material characterization. This work presents a new method enabling simultaneous assessment of the shear stress-strain curves in all three principal material planes. The method uses a small rectangular plate …

Characterization Of Fracture Toughness In Amorphous Diamond Like Carbon Thin Films And Coatings, Ronaksinh Parmar

Material Science and Engineering Theses - Archive

Any material containing a crack when subjected to a certain amount of load, will eventually fail. This failure of material can be either time consuming (ductile) or instant (brittle) depending on the type of material and amount of load applied. For one to be able to study fracture toughness, it is important to study the material's failure rate and how long it can withstand load without failure once a crack has been initiated. Ductile materials demonstrate high fracture toughness while brittle materials show lower fracture toughness and fail instantly once a crack has been initiated. Characterization of fracture toughness in …

Structural Integrity Of Tsvs In 3d Package Under Thermal Loading, Parinda Patel

Mechanical and Aerospace Engineering Theses - Archive

In this advanced technological era, all electronic equipments tend to be light in weight, and have high performance with low power consumption and low prices. Gain in both performance and cost via Moore's law is starting becoming difficult post 28nm technology node. Three dimensional chips staking with TSV technology has gained momentum to meet such requirements of significant miniaturization and power reduction which result in increased performance. Vertically interconnected TSVs provide the shorter effective electrical interconnect path, resulting in reduced signal latency between strata and greater signal bandwidth. Moreover, TSVs offer high density integration, increased number of input/output terminals and …

Considerations For Generating Accurate Linear Transfer Functions For Laminar Flow Transmission Line Dynamics, Sina Jasteh

Mechanical and Aerospace Engineering Theses - Archive

Modeling fluid lines for applications such as hydraulic fracturing has been studied for many years, and we know that the inverse frequency method presents very accurate solutions for systems with lines in almost all laminar flow cases. However, utilizing this method is not easy for all users, and requires experience and understanding of the method. In this study a simplified method is introduced for accurately modeling the transients in lines which requires minimum experience in utilizing inverse frequency methods; the accuracy and limits of this simplified method are studied. Also, alternative approaches are presented which improved the accuracy of the …

Optimal Design Of A Parallel Beam System With Elastic Supports To Minimize Flexural Response To Harmonic Loading, Bret R. Hauser

Mechanical and Aerospace Engineering Theses - Archive

Mechanical systems subject to vibration are prevalent across many industries. Harmonic problems can be especially challenging to optimize due to the likelihood that the response will be multi-modal; influenced by system natural frequencies throughout the design space. Further, analysis of these systems often involves large and complex computer models which require significant resources to execute. A parallel beam system, as evaluated with Finite Element Modeling (FEM), is used as an example in this work to demonstrate a proposed method of identifying an optimum in a constrained, multi-modal response environment with consideration for Expensive Black Box Functions. The presented method leverages …

Effects Of Transverse Shear Deformation On Composite Beams With Various Laminate Configurations And Boundary Conditions, Wei-Tsen Lu

Mechanical and Aerospace Engineering Theses - Archive

Analytical methods are developed for determining deflection of composite beams under transverse load with various boundary conditions and laminate configurations. The present methods include development of expression for 1-D equivalent bending stiffness with and without presence of twisting curvature and prediction of the beam deflection accounting for transverse shear effect. Finite element analysis of 3-D ANSYS models is conducted by using Solid186 elements. The present analytical model is executed by using MATLAB program. Both analytical and FEM models were first validated by using isotropic material in the model and comparing the existing solutions. The composite beams with rectangular cross-section and …

Novel Neuro-Dynamic Methods For Solving Robotic Planning And Control Problems, Ghassan M. Atmeh

Mechanical and Aerospace Engineering Dissertations - Archive

Robotic systems are growing more complex to cater to the tasks they are required to solve. Irrespective of these tasks the problem of planning and control must be solved for all robotic systems. In this dissertation a general description of that problem is given along with the issues that it faces. This problem concerns planning a trajectory in the operational space of the robot, i.e. the space in which a task is to be executed. Then solving the inverse kinematics problem to compute the joint positions that correspond to that trajectory. And lastly, controlling the robot to track those joint …

Reduced-Order Analysis Of Dual Mode Supersonic Combustion Ramjet Propulsion System, Vijay Gopal

Mechanical and Aerospace Engineering Theses - Archive

High speed propulsion systems typically possess relatively simple geometry but the complexity involved in the flow characteristics makes their analysis a challenging task. The current research work introduces a reduced order analytical model for a steady operation of dual mode SCRamjet (Supersonic Combustion Ramjet) propulsion system at design and off-design conditions. The model hopes to reduce analysis time and complexity to carry out parametric sweep studies for preliminary design of SCRamjet engines. The analytical model splits the analysis of SCRamjet engine into five interactive components namely: inlet, isolator, injector, burner and nozzle. Each component is modelled using physics of gas-dynamics …

Viscoelastic Effects On A Polyetherimide Cylinder With Constant Radial Deformation, Louis Edward Parkman

Mechanical and Aerospace Engineering Theses - Archive

The relaxation of an axisymmetric radially crimped joint is analyzed with the inner component being formed from the engineering grade polymer ULTEM^TM 1000 polyetherimide. Creep and Relaxation tests were performed at several temperatures in order to use Time Temperature Superposition theory to assemble a master curve for predictions at long times based on short time testing. The master curves for each test were fit to the appropriate Prony Series and all coefficients are tabulated for re-use. The elastic theory for the classic thick walled cylinder was reviewed and the conversion from elasticity to viscoelasticity was demonstrated. Strength predictions are …

Development Of A Numerical Tool To Study The Mixing Phenomenon Occurring During Mode One Operation Of A Multi-Mode Ejector-Augmented Pulsed Detonation Rocket Engine, Joshua Dawson

Mechanical and Aerospace Engineering Theses - Archive

A novel multi-mode implementation of a pulsed detonation engine, put forth by Wilson et al. [2], consists of four modes; each specifically designed to capitalize on flow features unique to the various flow regimes. This design enables the propulsion system to generate thrust through the entire flow regime. The multi-mode ejectoraugmented pulsed detonation rocket engine operates in mode one during take-o_ conditions through the acceleration to supersonic speeds. Once the mixing chamber internal flow exceeds supersonic speed, the propulsion system transitions to mode two. While operating in mode two, supersonic air is compressed in the mixing chamber by an upstream …

Use Of A Windbreaker To Mitigate High Speed Wind Loading On A Modular Data Center, Prasad Pramod Revankar

Mechanical and Aerospace Engineering Theses - Archive

The data centers that are located in open regions are subjected to various environmental risks. Earthquakes and very strong winds have the greatest effect on the structural integrity of the data centers. As the wind blows against the external structure, there is a buildup of pressure against the external structure which is translated to the supporting structure. Certain components of the data center like the inlet and exhaust dampers cannot withstand high wind speeds. Various kinds of fences have been used as windbreakers to prevent wind induced damage to objects. A windbreaker basically acts as a barrier to the upstream …

The Configurator: A Novel Approach To Enterprise Configuration Of Complex Software Systems, Thomas K. Wang

Mechanical and Aerospace Engineering Theses - Archive

Software systems are ubiquitous within aerospace technology. They are essentially the guidance, navigation, and control (GNC) of aircraft and satellites. Software systems are a primary component of satellite ground control systems, as well. Similarly, radar systems heavily utilize software systems. The design of aerospace software systems presents challenges outside of traditional aerospace or computer science domains. Mission operability and design constraints are balancing factors critical to the implementation phase of ground control software systems. Therefore, design decisions can often complicate the system architecture. Complexities within the architecture inevitably lead to challenges in the system integration phase. Numerous software source code …

Performance Evaluation Of Compliant Foil Seal, Sashidhar Raghuraman

Mechanical and Aerospace Engineering Theses - Archive

The concept of foil bearings has gained large acceptance in the industry and is been applied for various rotating equipment including air cycle machines, cryogenic turbo-expanders, centrifugal compressors and gas turbine engines. The ever-increasing demand for maintenance free and durable components has led to the development of compliant foil seals (CFS). Labyrinth and Brush seals have been widely employed for reducing the leakage flow at high pressure and temperature conditions, to enhance the overall performance of the system. Increase in the radial clearance to compensate the lack of their capability to accommodate the higher rotor orbits results in more leakage. …

Design And Structural Of A Fence Used For Protecting Modular Data Center From High Speed Wind, Nikhil Baviskar

Mechanical and Aerospace Engineering Theses - Archive

Various data centers built in an open area are occasionally susceptible to different kinds of natural calamities. Wind, either from any of the sources like hurricane, tornado or storm is one of those ecological dangers with high speed flow. These high speed winds can be responsible for downed power lines, trees and collapsing of buildings as well, the wind may adversely impact a data center’s structure. Windbreaker or wind fence is basically used to reduce the high speed of the wind resulting in the protection of structures or objects behind it. Some modular data centers which encounter problems of high …