Geochemical Evaluation Of High
Sulfate Levels In Ponca Creek,
Northeastern Nebraska,
2012
Air Force Center for Engineering and the Environment
Geochemical Evaluation Of High Sulfate Levels In Ponca Creek, Northeastern Nebraska, Jon C. Atkinson
United States Air Force: Publications
Most surface water and shallow groundwater occurring in northeastern Nebraska are of the calcium bicarbonate type, with minor concentrations (e.g., 10–200 mg/L) of sulfate (SO4). Examination of historical water quality data (major cations and anions) for Ponca Creek, a predominantly ephemeral streamin northeastern Nebraska, revealed that SO4 concentrations ranged from about 110 to almost 1000mg/L and contribute to a calcium sulfate hydrochemical facies. Consequently, most SO4 concentrations were above the U.S. Environmental Protection Agency secondary maximum contaminant level in drinking water of 250 mg/L. Sulfate concentrations for the same period for a nearby stream, Verdigre Creek, …
Specialized System Identification For Parafoil And Payload Systems,
2012
Georgia Institute of Technology - Main Campus
Specialized System Identification For Parafoil And Payload Systems, Michael Ward, Mark Costello, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
There are a number of peculiar aspects to parafoil and payload systems that make it difficult to apply conventional system identification procedures used for aerospace systems. Parafoil and payload systems are unique because typically there is very little sensor information available, the sensors that are available are separated from the canopy by a complex network of flexible rigging, the systems are very sensitive to wind and turbulence, the systems exhibit a number of nonlinear behaviors, and the systems exhibit a high degree of variability from flight to flight. The current work describes a robust system identification procedure developed to address …
Evaluation Of Multibody Parafoil Dynamics Using Distributed Miniature Wireless Sensors,
2012
University of Alabama - Huntsville
Evaluation Of Multibody Parafoil Dynamics Using Distributed Miniature Wireless Sensors, Chrystine M. Gorman, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Guided parafoils arc composed of two primary bodies, a payload and parafoil. The payload encompasses the majority ofthe ovcrdll system mass; however, the parafoil generates the majority of aerodynamic loads and is the sole source of control. Despite the canopy being the source of control, the sensor systems used for guidance are located away from the parafoil. Many multi body models exist in literature and use different degrees of freedom to represent parafoil-payload relative motion. However, in many cases, simulations are used to investigate how the relative motion between bodies affects the overall dynamics without experimental validation determining the accuracy …
Ua94/6/8 Student / Alumni Personal Papers Wku Terry Wilcutt,
2012
Western Kentucky University
Ua94/6/8 Student / Alumni Personal Papers Wku Terry Wilcutt, Wku Archives
WKU Archives Collection Inventories
Records created by and about Terry Wilcutt and manned space flights.
Cfd Study On Aerodynamic Effects Of A Rear Wing/Spoiler On A Passenger Vehicle,
2012
Santa Clara University
Cfd Study On Aerodynamic Effects Of A Rear Wing/Spoiler On A Passenger Vehicle, Mustafa Cakir
Mechanical Engineering Master's Theses
Aerodynamic characteristics of a racing car are of significant interest in reducing car-racing accidents due to wind loading and in reducing the fuel consumption. At the present, modified car racing becomes more popular around the world. Sports cars are most commonly seen with spoilers, such as Ford Mustang, Subaru Impreza, and Chevrolet Corvette. Even though these vehicles typically have a more rigid chassis and a stiffer suspension to aid in high-speed maneuverability, a spoiler can still be beneficial. One of the design goals of a spoiler is to reduce drag and increase fuel efficiency. Many vehicles have a fairly steep …
Vision-Based Testbeds For Control System Applicaitons,
2012
University of Central Florida
Vision-Based Testbeds For Control System Applicaitons, Robert Sivilli
Electronic Theses and Dissertations
In the field of control systems, testbeds are a pivotal step in the validation and improvement of new algorithms for different applications. They provide a safe, controlled environment typically having a significantly lower cost of failure than the final application. Vision systems provide nonintrusive methods of measurement that can be easily implemented for various setups and applications. This work presents methods for modeling, removing distortion, calibrating, and rectifying single and two camera systems, as well as, two very different applications of vision-based control system testbeds: deflection control of shape memory polymers and trajectory planning for mobile robots. First, a testbed …
Passive Wireless Antenna Sensors For Crack Detection And Shear/Compression Sensing,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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 …
Graph Theoretic Framework Based Cooperative Control And Estimation Of Multiple Uavs For Target Tracking,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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 …
Solution To Three Dimensional Incompressible Navier-Stokes Equations Using Finite Element Method,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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 …
Experimental And Numerical Investigation Of Mass Transfer In Microreactors,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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,
2012
University of Texas at Arlington
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 …
