Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Aerospace Engineering

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 7651 - 7680 of 11126

Full-Text Articles in Engineering

Aircraft Operations Based Mission Requirements, Robert A. Mcdonald Jan 2012

Aircraft Operations Based Mission Requirements, Robert A. Mcdonald

Aerospace Engineering

The mission capabilities of aircraft in the current commercial fleet are a combined result of many factors. The launch customer for each aircraft has a voice in determining the requirements. The manufacturer desires to best position the aircraft in the market considering their own aircraft and their competitors aircraft it will replace and compete with. Consequently, anyone considering the development of an aircraft to compete with or replace an aircraft in-service must do more than simply choose to meet the capabilities of that aircraft. This is especially true when unconventional systems are considered; the fundamental trade-offs for these systems may …

Go to article

High Performance Modeling Of Atmospheric Re-Entry Vehicles, Alexandre Martin, Leonardo C. Scalabrin, Iain D. Boyd Jan 2012

High Performance Modeling Of Atmospheric Re-Entry Vehicles, Alexandre Martin, Leonardo C. Scalabrin, Iain D. Boyd

Mechanical Engineering Faculty Publications

Re-entry vehicles designed for space exploration are usually equipped with thermal protection systems made of ablative material. In order to properly model and predict the aerothermal environment of the vehicle, it is imperative to account for the gases produced by ablation processes. In the case of charring ablators, where an inner resin is pyrolyzed at a relatively low temperature, the composition of the gas expelled into the boundary layer is complex and may lead to thermal chemical reactions that cannot be captured with simple flow chemistry models. In order to obtain better predictions, an appropriate gas flow chemistry model needs …

Go to article

Modeling Of Heat Transfer Attenuation By Ablative Gases During The Stardust Re-Entry, Alexandre Martin, Iain D. Boyd Jan 2012

Modeling Of Heat Transfer Attenuation By Ablative Gases During The Stardust Re-Entry, Alexandre Martin, Iain D. Boyd

Mechanical Engineering Faculty Publications

The great majority of modern space vehicles designed for planetary exploration use ablative materials to protect the payload against the high heating environment experienced during re-entry. In order to properly model and predict the aerothermal environment of the vehicle, it is imperative to account for the gases produced by ablation processes. In the case of charring ablators, where an inner resin is pyrolyzed at a relatively low temperature, the composition of the gas expelled into the boundary layer is complex and may lead to thermal chemical reactions that cannot be captured with simple flow chemistry models. In order to obtain …

Go to article

Effect Of Applied Magnetic Field On Shock Boundary Layer Interaction, Ovais U. Khan, Alexandre Martin Jan 2012

Effect Of Applied Magnetic Field On Shock Boundary Layer Interaction, Ovais U. Khan, Alexandre Martin

Mechanical Engineering Faculty Publications

The governing magneto-hydrodynamic (MHD) equations contain classical fluid dynamics equations along with coupled Maxwell’s magnetic induction equations. These equations model both advection and diffusion effects of electromagnetic field. However, available literature indicates that some previous investigations neglect the diffusion of magnetic field and considered only ideal MHD equations for modeling a typical MHD problem. In this work, the effects of magnetic field diffusion term also known as viscous magnetic term have been investigated over flow structure. Low magnetic Reynolds number approximation and ideal full MHD set of equations have been considered and solved using a four-stage modified Runge-Kutta scheme augmented …

Go to article

Defining, Teaching, And Assessing Engineering Design Skills, Nikos J. Mourtos Jan 2012

Defining, Teaching, And Assessing Engineering Design Skills, Nikos J. Mourtos

Faculty Publications

The paper discusses a systematic approach for defining, teaching, and assessing engineering design skills. Although the examples presented in the paper are from the field of aerospace engineering, the principles apply to engineering design in general. What makes the teaching of engineering design particularly challenging is that the necessary skills and attributes are both technical and non-technical and come from the cognitive as well as the affective domains. Each set of skills requires a different approach to teach and assess. Implementing a variety of approaches for a number of years at SJSU has shown that it is just as necessary …

Go to article

Encyclopedia Of Mathematics And Society: 'Engineering Design', Kimberly Edginton Bigelow Jan 2012

Encyclopedia Of Mathematics And Society: 'Engineering Design', Kimberly Edginton Bigelow

Mechanical and Aerospace Engineering Faculty Publications

Engineers design everything from automobiles and bridges to prosthetic limbs and sporting equipment. Designing is different from simply building in that it requires the adherence to a very systematic, yet iterative, process known as the “engineering design process.” This process is to engineers what the scientific method is to scientists-guiding steps that help ensure that the end result is the best it can be. When a new product is created without following the steps of the engineering design process, there is a higher likelihood that the product designed will lack some important aspect: the end product may not appropriately account …

Go to article

Geochemical Evaluation Of High Sulfate Levels In Ponca Creek, Northeastern Nebraska, Jon C. Atkinson Jan 2012

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, …

Go to article

Specialized System Identification For Parafoil And Payload Systems, Michael Ward, Mark Costello, Nathan Slegers Jan 2012

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 …

Go to article

Evaluation Of Multibody Parafoil Dynamics Using Distributed Miniature Wireless Sensors, Chrystine M. Gorman, Nathan Slegers Jan 2012

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 …

Go to article

Ua94/6/8 Student / Alumni Personal Papers Wku Terry Wilcutt, Wku Archives Jan 2012

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.

Go to article

Cfd Study On Aerodynamic Effects Of A Rear Wing/Spoiler On A Passenger Vehicle, Mustafa Cakir Jan 2012

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 …

Go to article

Vision-Based Testbeds For Control System Applicaitons, Robert Sivilli Jan 2012

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 …

Go to article

Passive Wireless Antenna Sensors For Crack Detection And Shear/Compression Sensing, Irshad Mohammad Jan 2012

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 …

Go to article

Illustration Of Fundamentals Of Mechanical Vibration Using Computable Document Format, Shiva Deshmukh Jan 2012

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 …

Go to article

Graph Theoretic Framework Based Cooperative Control And Estimation Of Multiple Uavs For Target Tracking, Mousumi Ahmed Jan 2012

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 …

Go to article

Lumped Parameter Modeling Of Fluid Line Dynamics With Turbulent Flow Conditions, Yi-Wei Huang Jan 2012

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 …

Go to article

Solution To Three Dimensional Incompressible Navier-Stokes Equations Using Finite Element Method, Shrinivas Ganesh Apte Jan 2012

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 …

Go to article

High Enthalpy Characterization Of The Uta Hypersonic Shock Tunnel, Raheem Temitope Bello Jan 2012

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 …

Go to article

Experimental And Numerical Investigation Of Mass Transfer In Microreactors, Wei-Tsen Han Jan 2012

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 …

Go to article

Experimental Identification Of Force Coefficients Of Hybrid Air Foil Bearings, Yu Ping Wang Jan 2012

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 …

Go to article

Experimental Feasibility Study Of Radial Injection Cooling Of Three-Pad Radial Air Foil Bearings, Suman K. Shrestha Jan 2012

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 …

Go to article

Thermal Behavior Of Dielectric Materials During Rapid Heating, Daipayan Sarkar Jan 2012

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 …

Go to article

Mitigation Of Hot-Spots In High-End Microprocessors Using Bulk And Thin Film Thermoelectric Coolers, Agat Hirachan Jan 2012

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. …

Go to article

Dynamic Performance Of Offset-Preloaded Two Pad Foil Bearings, Shrikant Ashok Yadav Jan 2012

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 …

Go to article

Dynamic Mode Decomposition Of Detonation Waves, Rahul Kumar Jan 2012

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 …

Go to article

Trajectory Generation And Constrained Control Of Quadrotors, Carlos Alberto Tule Jan 2012

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 …

Go to article

Stress Analysis In Curved Composite Due To Thermal Loading, Jared Cornelius Polk Jan 2012

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, …

Go to article

Using Gpu-Based Computing To Accelerate Finite Element Problems, Jacob Watt Jan 2012

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 …

Go to article

Determination Of Factors To Improve Effectiveness Of Triangulation Members For A Formula Sae Race Car Frame, Vikram Nair Jan 2012

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 …

Go to article

Characterization Of Uta Hypersonic Shock Tunnel, Derek Glenn Leamon Jan 2012

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 …

Go to article

First Prev Next Last