Engineering Commons^™

Impact Of Wireless Communication Delay On Load Sharing Among Distributed Generation Systems Through Smart Microgrids, Song Ci, Junjie Qian, Dalei Wu, Ali Keyhani

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Load sharing among distributed generation systems (DGS) is one of the most important topics in wireless-enabled smart microgrids, where a set of power inverters at different geographical locations work coordinately and collaboratively through wireless networks to meet the load requirement. Parallel power inverters operated in distributed generation systems rely on the underlying wireless communication channels to exchange power information among them for load sharing control. However, existing work in the area of load sharing has largely ignored the effect of wireless communication delay. Study has shown that the time-varying wireless communication delay may have a significant impact on the performance …

Manufacturing Process Modeling And Application To Intelligent Control, M. Laine Mears, Parakshit Mehta, Mathew Kuttolamadom, Carlos Montes, Joshua Jones, Wesley Salandro, Drew Werner

Publications

This paper reviews the major findings and intellectual contributions made over the past five years through research in the laboratory of Dr. Laine Mears at Clemson University. The focus of the laboratory’s work is in modeling of traditional and novel manufacturing processes, and application of such models to process control through model-based control strategies. Introducing intelligence to the manufacturing process through physical descriptions of the phenomena being controlled allows for more precise control as compared with reactive systems or those with simple feed-forward control schemes. For traditional processes, new approaches to process characterization allow for more precise control. For novel …

Saturated–Unsaturated Flow In A Compressible Leaky-Unconfined Aquifer, Phoolendra Mishra, Velimir Vesselinov, Kristopher Kuhlman

United States Department of Energy: Publications

An analytical solution is developed for three-dimensional flow towards a partially penetrating largediameter well in an unconfined aquifer bounded below by a leaky aquitard of finite or semi-infinite extent. The analytical solution is derived using Laplace and Hankel transforms, then inverted numerically. Existing solutions for flow in leaky unconfined aquifers neglect the unsaturated zone following an assumption of instantaneous drainage due to Neuman. We extend the theory of leakage in unconfined aquifers by (1) including water flow and storage in the unsaturated zone above the water table, and (2) allowing the finite-diameter pumping well to partially penetrate the aquifer. The …

Breaking Internal Waves On A Shelf Slope Using Numerical Simulations, Subhas K. Venayagamoorthy, Oliver B. Fringer

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The subject of internal waves interacting with bottom topographic features in the ocean has received much attention in the past few decades. This heightened interest is mainly due to a conjecture that breaking internal waves at boundaries can be a significant source of turbulence, leading to mixing and transport in the ocean. In this paper, we present results from high-resolution three-dimensional numerical simulations of an internal wave interacting with a shelf break in a linearly stratified fluid in order to highlight the instabilities that contribute to wave breaking over topography. The results show the development of a nonlinear internal bolus …

Business And Wealth Transfer In Nonmetropolitan Nebraska 2012 Nebraska Rural Poll Results, Rebecca J. Vogt, Cheryl A. Burkhart-Kriesel, Randolph L. Cantrell, Bradley Lubben, Odee Ingersoll, Shawn Kaskie

Rural Futures Institute: Publications

Includes

Executive Summary

Introduction

Businesses in the Community

Expected Number of Businesses in Local Community Five Years from Now by Community Size

Most Likely Outcome when Business Owner Leaves or Retires in Community

Business Exits and Transitions

Concern with Business Exits

Concern that Business Closings will Affect Ability to Get Needed Things by Occupation

Views of Community Strategies for Business Exits

Community Well-Being In Nonmetropolitan Nebraska 2012 Nebraska Rural Poll Results, Rebecca J. Vogt, Cheryl A. Burkhart-Kriesel, Randolph L. Cantrell, Bradley Lubben

Rural Futures Institute: Publications

Includes

Executive Summary

Trends in Community Ratings, 1996-2012

Community Change, 1996-2012

Expected Destination of Those Planning to Move: 1998-2012

Proportions of Respondents Very or Somewhat Satisfied with Each Service, 1997-2012

The Community and Its Attributes in 2012

Perceptions of Community Change by Community Size

Expected Community Change in Ten Years by Community Size

Satisfaction with Cellular Phone Service by Community Size

Difficulty or Ease of Leaving Community

Ease or Difficulty of Leaving Community by Length of Residence in Community

Feelings of Community Powerlessness by Community Size

Local Community Involvement Activities, 2002 and 2012

Distance from Goods and Services

Distance from …

Passive Wireless Antenna Sensors For Crack Detection And Shear/Compression Sensing, Irshad Mohammad

Mechanical and Aerospace Engineering Dissertations - Archive

Despite the fact that engineering components and structures are carefully designed against fatigue failures, 50 to 90% of mechanical failures are due to fatigue crack formation. The severity of the failure depends on both the crack length and its orientation with respect to the loading direction. Many types of sensors are available that can detect fatigue crack propagation. But, crack orientation detection has been rarely reported in the literature. We evaluated a patch antenna sensor capable of detecting crack propagation as well as crack orientation changes. The aim of the sensors would be to evaluate the real-time health condition of …

Illustration Of Fundamentals Of Mechanical Vibration Using Computable Document Format, Shiva Deshmukh

Mechanical and Aerospace Engineering Theses - Archive

The main objective of this study is focused on the better understanding of the basic concepts of mechanical vibrations and its free and ready availability to the entire student community all over the globe.In this study the concepts of vibrations are projected in the form of mathematical models. The mathematical models are designed using MATHEMATICA. These models are graphical in nature and can be animated at will. They are compiled and converted to the Computable Document Format referred as CDF.A very special function Manipulate is used in making the models. This function has given the models an ability to compute …

Photoelectrochemical Activity Of Titanium Dioxide Thin Films, Aida Mehdinezhad Roshan

Material Science and Engineering Theses - Archive

Titanium dioxide (TiO2) is considered as an oxide semiconductor with several unique properties, including environmental sensing capabilities, biocompatibility and photocurrent generation, long-term stability, cost efficiency, and chemical inertness. TiO2 thin films have a wide range of applications in dye-sensitized solar cells. TiO2 films have been deposited on two different substrates, aluminum and titanium. Two different methods used for deposition of the thin films namely: Plasma Electrolytic Oxidation (PEO) and Physical Vapor Deposition (PVD). In order to study the effect of roughness of the substrate on photocurrent generation of the deposited films, one group of substrates were “patterned” by Electrolytic Plasma …

Graph Theoretic Framework Based Cooperative Control And Estimation Of Multiple Uavs For Target Tracking, Mousumi Ahmed

Mechanical and Aerospace Engineering Dissertations - Archive

Designing the control technique for nonlinear dynamic systems is a significant challenge. Approaches to designing a nonlinear controller are studied and an extensive study on backstepping based technique is performed in this research with the purpose of tracking a moving target autonomously. Our main motivation is to explore the controller for cooperative and coordinating unmanned vehicles in a target tracking application.To start with, a general theoretical framework for target tracking is studied and a controller in three dimensional environment for a single UAV is designed. This research is primarily focused on finding a generalized method which can be applied to …

Lumped Parameter Modeling Of Fluid Line Dynamics With Turbulent Flow Conditions, Yi-Wei Huang

Mechanical and Aerospace Engineering Dissertations - Archive

A procedure for obtaining rational polynomial transfer functions representing ordinary differential equations for time domain transient response simulations of systems with fluid transmission lines with incompressible turbulent flow is formulated and presented. The method is based on the use of an inverse frequency least squares algorithm applied to the distributed parameter model for laminar flow with added lumped resistance to match the additional resistance associated with turbulence. Guidelines for using the algorithm are included with focus on the use of weighting parameters, the number of resonant modes to be included, and the bandwidth of the pressure/flow pulsation dynamics in the …

Computer Simulation, Fabrication And Characterization Of Inverse Frustum Nanosphere Metal Arrays For Fiber-Based Plasmonic Sensors, Jiaqi Wu

Material Science and Engineering Theses - Archive

In recent years, a number of metal nanostructures have attracted huge attention from scientists and researchers for its plasmonic property and surface enhanced Raman scattering effect. They have been utilized to monitor molecule adsorption, antibody-antigen reorganization event, and to enhance scattering for identification of molecules even in very low concentration. They both have also been exploited for real time biosensing.In this thesis, we are investigating a new plasmonic structure, inverse frustum nanosphere gold arrays, and exploring its optical fiber-based sensing application. The nanostructure was fabricated by electro-deposition of gold into pre-assembled templates, which are made of monodispered colloidal polystyrene nanospheres …

Cuinse2: Electronic Activities Of Grain Boundaries And Solar Cell Fabrication Studies, Mehmet Eray Erkan

Material Science and Engineering Dissertations - Archive

This dissertation is composed of three studies related to chalcopyrite solar cells. The first study is on electronic activities of grain boundaries (GBs) in CuInSe₂ (CIS). Despite being polycrystalline, chalcopyrite thin film solar cells have reached record power conversion efficiencies. This is against the classical understanding on the effect of GBs in semiconductor materials. Because GBs are expected to be recombination centers and barriers against the carrier flow, reducing the device efficiency. Therefore, a complete understanding on the electronic behavior of chalcopyrite GBs is missing. Moreover, the high efficiency chalcopyrite solar cells are grown with Na impurities which positively …

Solution To Three Dimensional Incompressible Navier-Stokes Equations Using Finite Element Method, Shrinivas Ganesh Apte

Mechanical and Aerospace Engineering Theses - Archive

A primitive variable mixed order formulation of finite element method for solving three dimensional incompressible Navier-Stokes equations is presented. The method of weighted residuals is used to obtain the approximate solutions of linear and nonlinear partial differential equations. The physical domain is discretized by using unstructured tetrahedral elements. Unequal order interpolation functions are used for pressure & velocity variables while the temporal discretization is carried out by using an implicit time marching scheme based on finite differencing.One of the major difficulties arising during the finite element solution of the incompressible Navier-Stokes equations is the efficient factorization/preconditioning of the resulting indefinite …

High Enthalpy Characterization Of The Uta Hypersonic Shock Tunnel, Raheem Temitope Bello

Mechanical and Aerospace Engineering Theses - Archive

In hypersonic wind tunnel testing, matching the flow enthalpy conditions for the hypersonic air-breathing corridor is of great importance in order to assure the validity of experimental results. The flow enthalpy of the UTA hypersonic shock tunnel is increased by a shock induced detonation driver. The detonation mixture consist of hydrogen and oxygen in stoichiometric quantities ( 2H2+O2 ? 2H2O). Experimental variations of pressure and the volume of the detonation section were performed to characterize the enthalpy limits, and overall performance of the UTA hypersonic shock tunnel. The UTA HST test section is designed for a nominal Mach number of …

Wear And Tribofilm Formation With Zinc-Free Antiwear Additives, Pradip Sairam Pichumani

Material Science and Engineering Theses - Archive

Engine oil is used in all internal combustion engines to lubricate the moving parts & mitigate the wear due to friction. Along with the mentioned two functions, engine oil also serves to protect the engine from corrosion, clean debris, improves sealing and serves in thermal conductivity. Engine oil is either derived from petroleum derivatives or made synthetically. A number of additives are added to the engine oil (Base oil) to improve its performance and longevity. Antioxidants, pour point depressants, viscosity index improvers, antifoaming agents, corrosion inhibitors, etc are some of the additives that are added to improve the engine oil‘s …

Experimental And Numerical Investigation Of Mass Transfer In Microreactors, Wei-Tsen Han

Mechanical and Aerospace Engineering Dissertations - Archive

In this work, two types of microreactors for reactions have been studied, which were involving multiple fluid phases: liquid-liquid (immiscible liquids) phase and gas-liquid phase. Investigation of mass transfer within reacting flows in microreactors has been carried out in these two multiphase systems. For the liquid-liquid phase, a microfluidic system was designed and fabricated to generate a slug flow pattern of immiscible liquids. This system was used to demonstrate the effect of the flow pattern on mass transfer and the effect on chemical reaction rate for a simple acid-base reaction. The reaction progression was tracked by measuring the pH along …

Experimental Identification Of Force Coefficients Of Hybrid Air Foil Bearings, Yu Ping Wang

Mechanical and Aerospace Engineering Theses - Archive

Successful applications for air foil bearings in small to midsize turbo-machinery have been acknowledged. Air foil bearings do not require oil lubricant thus they are capable of operating under much higher temperature than oil-lubricated bearings and they entail less maintenance costs if well-designed. However, when rotor size increases beyond 100 mm in diameter, reliability becomes an issue due to comparable increase in rotor weight with respect to increase in load capacity of the bearing. Furthermore, dry rubbing during starts and stops also causes concerns due to typical slow acceleration and deceleration characteristics of large turbo-machinery. The concept of hybrid air …

Experimental Feasibility Study Of Radial Injection Cooling Of Three-Pad Radial Air Foil Bearings, Suman K. Shrestha

Mechanical and Aerospace Engineering Theses - Archive

Air foil bearings use ambient air as a lubricant allowing environment-friendly operation. When they are designed, installed, and operated properly, air foil bearings are very cost effective and reliable solution to oil-free turbomachinery. Because air is used as a lubricant, there are no mechanical contacts between the rotor and bearings and when the rotor is lifted off the bearing, near frictionless quiet operation is possible. However, due to the high speed operation, thermal management is one of the very important design factors to consider. Most widely accepted practice of the cooling method is axial cooling, which uses cooling air passing …

Thermal Behavior Of Dielectric Materials During Rapid Heating, Daipayan Sarkar

Mechanical and Aerospace Engineering Theses - Archive

The objective of this research is to understand the temperature variation in dielectric materials of different geometry. The work is divided into three major segments. The Thermal Wave model has been taken into consideration as the classical Fourier law of heat conduction breaks down when a dielectric material of sub-micron geometry is heated rapidly. The first partof the work discusses primarily about the temperature distribution in a semi-infinite dielectric material, followed by the temperature profile in a finite body (plate) and finally mathematical formulation is presented for a two-layered body. The thermal wave equation is used because in dielectric materials …

Mitigation Of Hot-Spots In High-End Microprocessors Using Bulk And Thin Film Thermoelectric Coolers, Agat Hirachan

Mechanical and Aerospace Engineering Theses - Archive

Due to localized high heat fluxes, hot-spots are created in silicon chips. Cooling of the hot-spots is one of the major thermal challenges in today's integrated circuit (IC) industry. Many researches have been conducted to find ways to cool hot-spots using different techniques as uniform heating is highly desired. First part of the thesis focuses on cooling of hot-spot using conventional thermoelectric cooler (Melcor_CP1.0-31-05L.1) and a micro heat pipe. A chip package with conventional integrated heat spreader and heat sink was designed. Hot-spot was created at the center of the silicon die with background heat at rest of the area. …

Dynamic Performance Of Offset-Preloaded Two Pad Foil Bearings, Shrikant Ashok Yadav

Mechanical and Aerospace Engineering Theses - Archive

Commercial application of the air foil bearing (AFB) in microturbomachinary have been acknowledged. Absence of external pressurizing and lubricating system makes them light and compact. Simple construction, low friction drag and reliability at high speed operations are few more advantages of the AFBs. With all these advantages AFB proves to be the suitable option for oil-free small turbomachinery which includes micro gas turbines with shaft power less than 1000hp. Micro gas turbine generators are typically two shaft configuration with power generation capacity less than 500KW. Although many micro gas turbines with AFBs have been developed, due to the proprietary nature …

Dynamic Mode Decomposition Of Detonation Waves, Rahul Kumar

Mechanical and Aerospace Engineering Theses - Archive

Dynamic mode decomposition is applied to study the self-excited fluctuations supported by transversely unstable detonations. The focus of this study is on the effect of forcing on the limit cycle solutions. Using DMD, only the most coherent modes are analyzed. The most coherent modes in this case are the fundamental and the fourth harmonic. The analysis is based on the coherency of the self-excited detonation modes due to turbulence. Analysis reveals coherency is significantly affected with a turbulent Mach number greater than 0.3 and also the regions downstream of the shock are more affected by turbulence than the region just …

Trajectory Generation And Constrained Control Of Quadrotors, Carlos Alberto Tule

Mechanical and Aerospace Engineering Theses - Archive

Unmanned Aerial Systems, although still in early development, are expected to grow in both the military and civil sectors. As part of the UAV sector, the quadrotor helicopter platform has been receiving a lot of interest from various academic and research institutions because of their simplistic design and low cost to manufacture, yet remaining a challenging platform to control. Four different controllers were derived for the trajectory generation and constrained control of a quadrotor platform. The rst approach involves the linear version of the Model Predictive Control (MPC) algorithm to solve the state constrained optimization problem. The second approach uses …

Stress Analysis In Curved Composite Due To Thermal Loading, Jared Cornelius Polk

Mechanical and Aerospace Engineering Theses - Archive

Many structures in aircraft, cars, trucks, ships, machines, tools, bridges, and buildings, consist of curved sections. These sections vary from straight line segments that have curvature at either one or both ends, segments with compound curvatures, segments with two mutually perpendicular curvatures or Gaussian curvatures, and segments with a simple curvature. With the advancements made in multi-purpose composites over the past 60 years, composites slowly but steadily have been appearing in these various vehicles, compound structures, and buildings. These composite sections provide added benefits over isotropic, polymeric, and ceramic materials by generally having a higher specific strength, higher specific stiffnesses, …

Using Gpu-Based Computing To Accelerate Finite Element Problems, Jacob Watt

Mechanical and Aerospace Engineering Theses - Archive

Historically Graphics Processing Units (GPU) have been used for offloading graphical visualization and made popular in use for video games, but with the development of NVIDIA's CUDA architecture and programing language there has been an increase in the use of GPUs in general purpose (GPGPU) programing. Problems involving large systems of linear equations, such as the Finite Element Analysis (FEA), can benefit greatly from the parallel computing capabilities of GPUs. In my thesis I will solve Poisson's equation and discuss the advantages and disadvantages of the massively parallel environment of GPUs. I will show that on a unstructured grid that …

Determination Of Factors To Improve Effectiveness Of Triangulation Members For A Formula Sae Race Car Frame, Vikram Nair

Mechanical and Aerospace Engineering Theses - Archive

This thesis suggests which factors have significant effect on the torsional and flexural stiffness of a space frame without contributing excessively to its weight. These factors are used as design variables to display the interaction plots generated by performing a Design of Experiments (DOE) using the Hyperstudy tool in Hyperworks by Altair®. The DOE will also provide a mathematical model which can help predict the responses by varying several factors in the design. The node - element models are created in ANSYS classic and are analyzed for various load cases that are representative of the loads on a formula SAE …

Characterization Of Uta Hypersonic Shock Tunnel, Derek Glenn Leamon

Mechanical and Aerospace Engineering Theses - Archive

Characterization of a hypersonic shock tunnel was performed under low enthalpy conditions. A rake was designed and fabricated to measure pitot pressure and heat flux at three axial locations in the test section. Pitot pressures at three locations provided an indication of the inviscid core. Thin film RTD sensors with a fast response time were fabricated to measure the heat flux under these low enthalpy conditions. The Cook-Felderman algorithm was used to estimate the heat flux from the temperature history. Results for the first millisecond of test time showed a probe tip surface temperature increase of 15-20 K and a …

Computational Study Of Heat Transfer Enhancement For A Dimpled Surface In A Channel, Abhijit Paranjape

Mechanical and Aerospace Engineering Theses - Archive

Heat transfer augmentation techniques have gained great importance in different engineering applications to deal with thermal management issues. In this work, a numerical investigation was carried out to see the effects of spherical dimple arrays on heat transfer characteristics in a channel. These effects were observed for dimples on the bottom wall of the channel for laminar airflows. The effects of a 21×7 staggered array and a 19×4 inline array on the bottom wall were investigated using a 3D steady viscous computational fluid dynamics package with an unstructured grid. The heat transfer characteristics were studied as a function of the …

Spur Gear Analysis Using Mathcad, Jaydeep K. Panchal

Mechanical and Aerospace Engineering Theses - Archive

In gear manufacturing applications, it is required to calculate surface stress and bending stress with minimum error. This thesis represents engineering calculation of bending and surface compression of external teethed involute spur gear. One may change the input values to calculate the engineering data for gears. The freedom of changing input values gives the capability to program to calculate for factor, Y; and the bending geometry factor, J to analyze spur gear geometry. Here the engineering gear calculation has been done by developing program in Mathcad software. The program is designed to calculate surface and bending stress data by input …