Mechanical Engineering Commons^™

Alkaline Fuel Cell Engineering And Testing, James Brunton, David Kennedy, Eugene Coyle

Conference Papers

A fuel cell is a device that directly converts the chemical energy of reactants (a fuel and an oxidant) into low d. c. electricity [1]. Used in conjunction with other sustainable energy options, hydrogen and fuel cell technology can provide a realistic alternative to fossil fuels. Although research is continuing in many areas we are no closer now to commercialisation than ten to twenty years ago. This is due to a number of key reasons, some of which include efficiency, scale, accessories and power output. This paper outlines the benefits that could be derived from switching to a hydrogen based …

A Numerical Acoustic Fluid-Structure Model Of A Therapeutic Ultrasound Angioplasty Device, Graham Gavin, M.S. J. Hashmi, Finbar Dolan, Garrett Mcguinness

Conference Papers

Ultrasonic angioplasty involves the use of ultrasonic vibrations delivered to the distal-tip of small diameter wire waveguides and is an emerging technology the may have potential use in the treatment of complicated atherosclerotic plaques during cardiovascular surgery. Complicated plaques, including chronic total occlusions and calcified lesions, seriously reduce success rates during standard intervention involving guidewire access, followed by balloon dilation or stent delivery. The large amplitude (0-150 μm) wire waveguide distal-tip displacements in the low-frequency ultrasonic (18-45 kHz) range have been shown to disrupt plaque material by direct contact ablation and cavitation, acoustic streaming and pressure wave components in adjacent …

Including Embodied Energy Considerations At The Conceptual Stage Of Building Design, Y. Yohanis, Brian Norton

Articles

Elevated operating temperatures reduce the solar to electrical conversion efficiency of building integrated photovoltaic devices (BIPV). Phase change materials (PCM) can be used to passively limit this temperature rise although their effectiveness is limited by their low thermal conductivities and by crystallization segregation during solidification. This paper presents an experimental evaluation of the effects of convection and crystalline segregation in a PCM as a function of efficiency of heat transfer within the finned PV/PCM system. The thermal performances of bulk PCM with crystallization segregation for different internal fin arrangements are presented. It is noted that the addition of internal fins …

Test 1891: Kubota L5030 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1881: Mccormick Xtx 200/Mtx 185 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1875: Challenger Mt 635b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1878: Challenger Mt 665b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1883: Agco Lt75a Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1889: John Deere 8430t 16 Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Force Measurements On A Flapping And Pitching Wing At Low Reynolds Numbers, Kakkattukuzhy M. Isaac, Anthony Colozza, Jessica Rolwes

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Force measurements from experiments conducted in water on a flapping-and-pitching thin flat plate wing of semi-elliptic planform at low Reynolds numbers are reported. Time varying force data, measured using a force transducer, provide a means to understand the mechanisms that lead to enhanced performance observed in insect flight compared to fixed wing aerodynamics. Experimental uncertainties associated with low level (∼1N) fluid dynamic force measurements on flapping-and-pitching wings are addressed. a previously proposed pitching mode in which the leading edge and trailing edge switch roles to allow using cambered airfoils has been shown to be viable and may have advantages over …

Effects Of Welding Current In Gas Metal Arc Welding, Junling Hu, Tai Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In gas metal arc welding (GMAW), current is one of the most important factors affecting the mode of metal transfer, weld pool dynamics and subsequently the weld quality. in this paper, the comprehensive model recently developed by the authors was used to study the effects of different current levels on the droplet formation, plasma generation, metal transfer, and weld pool dynamics in GMA welding. Two welding currents were studied, including one low current and one high current. at each current level, the transient temperature and velocity distributions of the arc plasma and the molten metal, and the shapes of the …

Analysis Of Damage In Laminated Automotive Glazing Subjected To Simulated Head Impact, Shuangmei Zhao, Li Chai, S. D. Barbat, Lokeswarappa R. Dharani

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During vehicle accidents, occupant's head impacting on windshield or side window is commonly observed. Any attempt to design glazing that minimizes injury to and death of occupants during a vehicle accident requires a thorough understanding of the mechanical behavior of automotive glazing subjected to head impact loads. A continuum damage mechanics (CDM) based constitutive model is developed and implemented into an axisymmetric finite element model to study the failure and impact resistance of laminated automotive glazing subjected to simulated head impact. An anisotropic elastic damage tensor with a linear damage evolution law is chosen to model the failure of the …

Neural Network Approach For Obstacle Avoidance In 3-D Environments For Uavs, Vivek Yadav, Xiaohua Wang, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper a controller design is proposed to get obstacle free trajectories in a three dimensional urban environment for unmanned air vehicles (UAVs). The controller has a two-layer architecture. In the upper layer, vision-inspired Grossberg neural network is proposed to get the shortest distance paths. In the bottom layer, a model predictive control (MPC) based controller is used to obtain dynamically feasible trajectories. Simulation results are presented for to demonstrate the potential of the approach.

Nonlinear Control Concepts For A Ua, Vijayakumar Janardhan, Derek Schmitz, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A reconfigurable flight control method is developed to be implemented on an Unmanned Aircraft (UA), a thirty percent scale model of the Cessna 150. This paper presents the details of the UA platform, system identification, reconfigurable controller design, development, and implementation on the UA to analyze the performance metrics. A Crossbow Inertial Measurement Unit provides the roll, pitch, and yaw accelerations and rates along with the roll and pitch. The 100-400 mini-air data boom from SpaceAge Control provides the airspeed, altitude, angle of attack, and the side slip angles. System identification is accomplished by commanding preprogrammed inputs to the control …

Dynamic Re-Optimization Of A Spacecraft Attitude Controller In The Presence Of Uncertainties, Nishant Unnikrishnan, S. N. Balakrishnan, Radhakant Padhi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Online trained neural networks have become popular in recent years in the design of robust and adaptive controllers for dynamic systems with uncertainties due to their universal function approximation capabilities. This paper discusses a technique that dynamically reoptimizes a Single Network Adaptive Critic (SNAC) based optimal controller in the presence of unmodeled plant uncertainties. The SNAC based optimal controller designed for the nominal plant model no more retains optimality in the presence of uncertainties/unmodeled dynamics that may creep up in the system equations during operation. This calls for a strategy to re-optimize the existing SNAC controller with respect to the …

Experimental Simulation Of Lightning Optical Emissions In Clouds, Anil Ogale, Kunal Mitra, Arindam Banerjee

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The objective of the study is to experimentally determine the information content of lightning optical emissions through clouds. Clouds affect the amplitude of lightning signals and the apparent dimensions of the optical source. Multiple scattering from the cloud media also alters the shape of the temporal profile of the lightning signal. The goal is to provide accurate estimates of the arrival time delay and temporal pulse width broadening of output signals emitted from clouds for different cloud and lightning parameters. Experiments conducted in the laboratory yield a temporally broadened pulse with an overall decrease in the peak and a delay …

Optimal Impulse Control Of Systems With Control Constraints And Application To Hiv Treatment, Vivek Yadav, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, conditions for optimal impulse control of an impulsive system with constraints on control are derived. These hold for a system whose states can be changed instantaneously at discrete times with impulses while a continuous control is being applied between those times. The conditions derived are applied to the problem of optimal HIV treatment. Simulation results are presented to show the treatment procedure. The results obtained show that the intervention method developed leads to good results.

Robust Shape Design Techniques For Steady-State Metal Forming Processes, Jalaja Repalle

Browse all Theses and Dissertations

Metal forming is a process that transforms a simple shape of a workpiece into a predetermined complex shape through the application of compressive/tensile forces exerted by dies. In the design of a forming process, the only factors that are known are the final component shape and the material with which it is to be made. Then the engineer has to design a process to make defect-free product, subject to limitations of shape, material properties, cost, time, and other such factors. The design cycle can be enhanced if performance sensitivity information is available that could be used with any commercially available …

Test 1871: John Deere 5203 Diesel 9-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1870: John Deere 5103 Diesel 9-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1884: John Deere 8130 Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1888: John Deere 8330t Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1887: John Deere 8330 Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1885: John Deere 8230 Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Study Of Heat Transfer Characteristics Of Impinging Air Jet Using Pressure Andn Temperature Sensitive Luminescent Paint, Quan Liu

Electronic Theses and Dissertations

Luminescent coating measurement system is a relatively new technology for quantitative pressure and temperature measurement. Usually referred to as Pressure Sensitive Paint (PSP) and Temperature Sensitive Paint (TSP), luminescent coatings contain sensor molecules, which undergoes a luminescent transition when excited with light of proper wavelength. The reaction is pressure and/or temperature sensitive. The image of TSP or PSP coated model surface can be captured with a scientific grade camera and then processed to obtain full field temperature and pressure distribution with very high fidelity. The preparation time of the technique is short. The measurement system offers an economic alternative to …

Preliminary Study On The Impact Of Impingement On The Effectiveness Of Film Cooling In The Presence Of Gas Path Pressure Gradient, Anil Peravali

Electronic Theses and Dissertations

Impingement is the most commonly used method of cooling in the hot stages of gas turbines. This is often combined with film cooling to further increase the cooling performance. The mainstream flow where in the coolant films discharge often has large stream wise pressure variations. All existing studies on coupled film and impingement cooling concentrated on the effect of the film depletion on the impingement heat transfer. This study investigates the impact of impingement on film cooling, where the jets impinging on a flat plate are depleted through arrays of film cooling holes in the presence of pressure gradient in …

A Fluid Structure Interaction Model Of Intracoronary Atherosclerotic Plaque Rupture, Eric Teuma-Melago

Electronic Theses and Dissertations

Plaque rupture with superimposed thrombosis is the primary cause of acute coronary syndromes of unstable angina, myocardial infarction and sudden death. Although intensive studies in the past decade have shed light on the mechanism that causes unstable atheroma, none has directly addressed the clinical observation that most myocardial infarction (MI) patients have moderate stenoses (less than 50%). Considering the important role the arterial wall compliance and pulsitile blood flow play in atheroma rupture, fluid-structure interaction (FSI) phenomenon has been of interest in recent studies. In this thesis, the impact is investigated numerically of coupled blood flow and structural dynamics on …

Experiments In Pool Boiling Heat Transfer And Nucleationdynamics Of High Pressure Refrigerants, Daniel Joo

Electronic Theses and Dissertations

A high pressure pool boiling experiment of pressurized R134a is designed and built, utilizing thermochromatic liquid crystal techniques. Liquid crystals thermo-chromatography uses encapsulated liquid crystals that are sensitive to temperature. When exposed to hot temperatures the crystal reflect a blue/violet color, and when exposed to cooler temperatures it reflects a red/orange color. The color value or hue is proportional to its temperature. Using this technique this experiment is capable of studying the physics and thermodynamics of refrigerants under nucleate pool boiling. The main objective of this experiment was the design of the experimental setup. Various designs were tested and validated, …

Economic Evaluation Of Integrating Biodiesel Production With A Dry Mill Ethanol Plant, Steven Bly

The Journal of Undergraduate Research

Biodiesei is produced by adding methyl ester products to diesel fuel. Base catalyzed transesterification of oil with methanol is the primary process used today. Current dry mill ethanol production facilities allow the com oil to pass through the process where it becomes part of the dried distiller's grain with solubles (DDGS), a lower valued feed co-product. This study evaluated the economic feasibility of integrating a biodiesel production facility with existing and/or new dry mill ethanol plants. The following methods for com oil separation were considered; hexane extraction of com oil from the dried distiller's grain stream, initial germ separation and …

Design And Performance Evaluation Of An Integrated Miniature Single Stage Centrifugal Compressor And Permanent Magnet Synchronous Motor, Dipjyoti Acharya

Electronic Theses and Dissertations

An attempt has been made in this present work to design, fabricate and performance evaluate an integrated single stage centrifugal compressor and permanent magnet synchronous motor which is a key component of the reverse brayton cycle cryocooler. An off the shelf compressor – the driven and electric motor – the driver was not available commercially to suffice the requirements of the reverse brayton cryocooler. The integrated compressor-motor system was designed and tested with air as the working fluid at mass flow rate of 7.3 grams per sec, with a compression ratio of 1.58 and driven by a 2 KW permanent …