Mechanical Engineering Commons^™

Commissioning Of A Dynamic Mechanical Analyzerfor The Characterization Of Low Temperature Nitife Shape Memory Alloys, Maruthi Diwakar Nandiraju

Electronic Theses and Dissertations

NiTiFe shape memory alloys can undergo transformations between cubic, trigonal and monoclinic phases at low temperatures. The low hysteresis associated with the trigonal R-phase transformation make them candidates for actuator applications at low temperatures. However, the literature available on these alloys is limited and there is a need to establish processing structure-property correlations. This study was undertaken with the objective of determining and understanding such correlations in a Ni46.8Ti50Fe3.2 alloy. First, a dynamic mechanical analyzer (DMA) was successfully commissioned to facilitate mechanical testing between -150 and 600ºC. The experiments performed over selected ranges of stress and temperature probed a range …

Lattice Vibration Study Of Silica Nanoparticle In Suspension, Parveen Sachdeva

Electronic Theses and Dissertations

In recent years considerable research has been done in the area of "nanofluids". Nanofluids are colloidal suspensions of nanometer size metallic or oxide particles in a base fluid such as water, ethylene glycol. Nanofluids show enhanced heat transfer characteristics compared to the base fluid. The thermal transport properties of nanofluids depend on various parameters e.g. interfacial resistance, Brownian motion of particles, liquid layering at the solid-liquid interface and clustering of nanoparticles. In this work atomic scale simulation has been used to study possible mechanisms affecting the heat transfer characteristics of nanofluids. Molecular dynamics simulation for a single silica nanoparticle surrounded …

Oscillatory Flow As A Means Of Enhanced Species Separation: A Three Dimensional Time-Accurate Cfd Analysis, Jennifer Crain

Electronic Theses and Dissertations

A fluid that contains species in the presence of a concentration gradient generates unusual phenomena when it is forced into pulsatile motion. For example, each species in the fluid has an enhanced mass transport due to pure molecular diffusion. This enhancement takes place even if there is no net total flow over a cycle of the pulsatile motion. When more than one species in dilute amounts is present in an otherwise pure fluid, called a carrier, each species is transported at a different rate thereby causing a partial separation of the species. This idea traces back to hyperventilation studies done …

System Identification And Fault Detection Of Complex Systems, Dapeng Luo

Electronic Theses and Dissertations

The proposed research is devoted to devising system identification and fault detection approaches and algorithms for a system characterized by nonlinear dynamics. Mathematical models of dynamical systems and fault models are built based on observed data from systems. In particular, we will focus on statistical subspace instrumental variable methods which allow the consideration of an appealing mathematical model in many control applications consisting of a nonlinear feedback system with nonlinearities at both inputs and outputs. Different solutions within the proposed framework are presented to solve the system identification and fault detection problems. Specifically, Augmented Subspace Instrumental Variable Identification (ASIVID) approaches …

Test 1882: Mccormick Xtx 215 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1876: Challenger Mt 645b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1890: John Deere 8530 Ivt, Nebraska Tractor Test Lab, John Deere

Nebraska Tractor Tests

No abstract provided.

Test 1873: John Deere 8430 16 Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1874: John Deere 8430 Ivt, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1872: John Deere 5303 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 1886: John Deere 8230t 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 …

Nebraska Summary 559: Massey Ferguson 5470 Dyna 4 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 …

System Optimization For Realizing A Miniaturized Gas Chromatograph Sensor For Rapid Chemical Analysis, Abhinav Bhushan

LSU Doctoral Dissertations

Rapid and comprehensive on-site analysis of chemicals in applications ranging from industrial process control to homeland security is of significant importance to improve the environment and save human life. The need for sensors that are fast, reliable, and portable has never been greater. For the challenging task of on-site instrumentation, where power sources can be limited, shrinking the size of the device is the most effective way to conserve power. Although gas chromatography is a mature technique well suited for these applications, current instrumentation has deficiencies that limit its usage. Speed of analysis and non portability are severe hindrances to …

Uv-Liga Micro-Fabrication Of Inertia Type Electrostatic Transducers And Their Application, Seok Jae Jeong

LSU Doctoral Dissertations

This dissertation discusses the design, working principles, static & dynamic analysis and simulation, mechanics of material, applied MEMS technology, micro-fabrication, and experimental testing of two types of micro-transducers: micro-power relay and micro-accelerometer. Several possible design concepts were proposed, and the advantages and disadvantages of electrostatic working principles were also discussed. Transducers presented in this research used electrostatic force as a driving force in the micro-relay and capacitance as a sensing parameter in the micro-accelerometer. There was an analogy between the micro-relay and the micro-accelerometer in their theoretical approach and fabrication processes. The proposed micro-transducers (micro-relay and micro-accelerometer) were fabricated using …

Theory Of Curvature-Dependent Disjoining Pressure And Its Application To Liquid Films, Jin Zhang

LSU Doctoral Dissertations

A liquid film of thickness h < 100 nm is subject to additional intermolecular forces, which are collectively called disjoining pressure Pi. Since Pi dominates at small film thicknesses, it determines the stability and wettability of thin films. Current theory for uniform films gives Pi = Pi(h). It becomes unbounded as h -> 0. We present a theory of curvature-dependent disjoining pressure. The new Pi depends on the curvature hxx, slope hx, and h. When this theory is implemented for Lennard-Jones liquid films, the new Pi is bounded as h -> 0. We show that this Pi captures three regimes of drop behavior (complete wetting, partial wetting, and pseudo partial wetting) without altering the signs of the long and short-range interactions. We also find that a drop with a uniform film is linearly stable, whereas a drop without a uniform film is unstable. Evaporating thin films is …

Tribological Aspects Of Journal Bearings Focusing On The Stribeck Curve, Xiaobin Lu

LSU Doctoral Dissertations

The dissertation focuses on the frictional characteristics of journal bearings as represented by the Stribeck curve. The behavior of lift-off speed and the factors that affect it are explored. An equation is proposed for predicting the lift-off speed. The comparison between the experimental results of oil- and grease-lubricated journal bearings with a mixed elastohydrodynamic lubrication model for line contacts is indicative of good agreement in the mixed lubrication regime. Efforts are made to modify the surface profile of bushing by putting dimples on its surface. Experimental results show that with proper dimensions of dimples, the friction performance of journal bearings …

Jet Impingement Cooling Configurations For Gas Turbine Combustion, Eric Ian Esposito

LSU Master's Theses

Impinging jets are commonly used to enhance heat transfer in modern gas turbine engines. Impinging jets used in turbine blade cooling typically operate at lower Reynolds numbers in the range of 10,000 to 20,000. In combustor liner cooling, the Reynolds numbers of the jets can be as high as 60,000. The present study is aimed at experimentally testing two different styles of jet impingement geometries to be used in backside combustor cooling. The higher jet Reynolds numbers lead to increased overall heat transfer characteristics, but also an increase in crossflow caused from spent air. The crossflow air has the effect …

Numerical Solution Of Flow Resistance In Outflow Pathway And Intravitreal Drug Delivery In Vitrectomised Eyes, Jyoti Gururaj Kathawate

LSU Master's Theses

In this study, numerical computations of the ocular fluid dynamics in a human eye are presented with a perspective of understanding the mechanisms of increased flow resistance. In the present study, the TM is represented as a multilayered-graded porous structure with specific pore size and void fraction. The flow patterns and pressure distribution in anterior chamber are analyzed to delineate key flow mechanism; the shear stresses on the lens, iris and IW of SC are also examined to locate the maximum values. Inside the human eye, the largest pressure drop occurs across JCT and IW of SC. The highest pressure …

Pulsed Vertical Jet In Cross Flow At Mean Blowing Ratios 0.35 And 0.45, Pierre-Emmanuel Jacques Joseph Bouladoux

LSU Master's Theses

This thesis deals with a pulsed vertical jet transverse to a cross flow (U_∞=1.6m/s) at mean blowing ratios 0.35 and 0.45. First the reasons of this study are explained and the previous work in the field is described. Then the experimental setup, the experimental procedures and the data processing are detailed. The system (wind tunnel and jet) is characterized before studying the Jet in Cross Flow (JICF). The JICF is explored under unforced and forced conditions through LASER sheet visualizations and constant temperature anemometry (CTA) measurements using hot-wire sensors. Blowing ratios ranging from 0.150 to 0.600 are studied …

Two-Phase Flow In High Aspect Ratio, Polymer Microchannels For Reagent Delivery Applications, Estelle Evans

LSU Master's Theses

Multiphase flow in microfluidics is an increasingly growing field, especially in biotechnology. For instance, a steady-state slug flow would benefit lab-on-a-chip drug delivery methods. This flow would not only use minute amounts of reagents, but it would also decrease the sample processing time. Thus, researching a steady-state plug flow in a microchannel is beneficial to the drug delivery field. Five PMMA, directly-milled microchannels [2: Aspect Ratio 1 (with and without pressure ports, 2): Aspect ratio 2 (with and without pressure ports), and 1: Aspect Ratio 3 (without pressure ports)] were manufactured. These channels were then cleaned, and a PMMA cover …

Simulations Of A Modified Micro-Scale Electrophoretron, Nada Elmajdoub

LSU Master's Theses

This paper presents theoretical analysis and numerical simulations of a modified micro-scale electrophoretron adapted for cycling reaction applications (PCR, LDR...). The electrophoretron consists of a closed-loop microchannel. If one part of the length of the channel has an electroosmotic mobility of an opposite sign than the remaining part, a continuous cyclic motion of the fluid can be sustained if a potential difference is applied on two electrodes strategically placed along the channel. Conservation of mass leads to the formation of a pressure gradient and a related hydrodynamic flow. Under appropriate combination of design parameters, the combined Electroosmotic -hydrodynamic flow contributes …

Modeling Fabrication And Characterization Of A Bio-Micro Thermoelectric Device For Highly Localized Temperature Control, Aparna Prabhakar

LSU Master's Theses

There is an ever expanding interaction between the fields of micro-electromechanical systems (MEMS) and biology to develop devices to monitor, control and act on living systems. Particularly in the field of cryobiology, there is a need to monitor and control temperature at the cellular level. An important step towards achieving this aim is to fabricate an array of microscale thermoelectric actuators. As a first step for towards achieving such localized control of temperatures in cells and tissues, an array of individually addressable micro-thermoelectric coolers (µTECs) were modeled, characterized, and fabricated. Prefabrication experimentation and modeling were carried out to understand the …

Modeling Of Fiber Reinforced Polymer Confined Concrete Cylinders, Indrani V. Volety

LSU Master's Theses

Fiber Reinforced Polymer (FRP) confined concrete columns have been developed for new construction and rebuilding of concrete piers/piles in engineering structures. Design of these FRP confined concrete columns requires an accurate estimate of the performance enhancement due to the confinement mechanism. Therefore, the key is to develop a confinement model, a model that relates the confined concrete strength with the unconfined concrete strength and the confining pressure provided by the FRP. Due to its closed-form expression and ease of application, design-oriented confinement models predominate in designing FRP confined concrete columns. Design oriented models are directly based on the interpretation of …

Molecular Dynamics Simulation Study Of Grain Boundary Migration In Nanocrystalline Pd, Shengyu Wang

LSU Master's Theses

We present a new methodology for measuring the grain boundary mobility for curved boundaries using molecular-dynamics simulation of grain growth in a small, specifically tailored Pd nanocrystalline structure. In the model system, the boundaries move under the forces provided by their curvature and in the presence of the triple junctions. As a consequence of grain boundary migration the boundary area per unit volume is reduced and the mean grain size of grains increases with time. Our investigation shows that at elevated temperatures the activation energy for grain growth in this specifically tailored microstructure is very close to that of grain …

A New Method To Determine Radiative Properties Of Rough Solid Surfaces, Raghu Nandan Mutukulla

LSU Master's Theses

The radiative properties of the rough surfaces are important both from fundamental and practical standpoint. Thus, there is a need to determine the effect of roughness on radiative properties of materials accurately, as these properties effect the performance of electronic devices, communication devices, optical sensors, and furnaces, amongst others. The effects of roughness are assessed by measuring the reflection coefficients from the carbon rod surfaces and steel 1086 samples over the range of angles 25 to 75 in the visible range and near infrared region. Different levels of roughness are induced on the surfaces by utilizing different grid size sand-paper …

Heat Transfer And Flow Characteristics Inside A Gas Turbine Combustor, Yap-Sheng Goh

LSU Master's Theses

Heat transfer and flow characteristics inside a typical can-annulus gas turbine combustor are investigated. This is the first study in a public domain to focus on the convective heat loads to combustor liner due to swirling flow generated by swirler nozzles. The objectives of this study are to physically design an experimental combustor test model, to perform local accurate heat transfer and flow measurements, and to better understand the fundamental thermo-fluid dynamic effects inside a combustor equipped with a swirler nozzle provided by Solar Turbines Inc. The local temperature and heat transfer distribution were determined to locate the heat transfer …

Thermal Management Of Micro Gas Chromatographs, Chetan Ramesh

LSU Master's Theses

Gas chromatography is an analytical technique for separating and analyzing individual components in a gas mixture. Applications of gas chromatographs (GCs) include chemical analysis, environmental maintenance, green house gases monitoring, and forensic analysis when used in conjunction with mass spectrometry. There has been a tremendous interest in miniaturization of gas chromatograph systems because of significantly reduced size, portability, fast response times, low power consumption and low cost. Isothermal analysis is a chromatographic analysis at one column temperature. In temperature programming, a linear increase of column temperature with time is used during the course of the analysis. Temperature programming facilitates separation …

Experimental Analysis Of Mechanical Seal Design With Enhanced Thermal Performance, Ainsworth Gidden

LSU Master's Theses

For industries that use pumps and mixers in their process operations, it is of paramount importance to control the leakage from these equipments. The leakage presents safety hazards and economic loss. It is widely believed that the majority of downtime associated with a pump or a mixer is the result of a mechanical seal failure. Therefore, it is important for these industries to have a mechanical seal that is a reliable performer and enables a longer operational life than what exist in the market at present. The aim of this research was to design and test a mating ring with …

A Thermodynamic Model For Wear In Sliding Contact, Susheel Brahmeshwarkar

LSU Master's Theses

Consideration of wear, an irreversible phenomenon, is a very important criterion in design. The knowledge of wear and its behavior enables one to make major considerations to conceptualize and design efficient machinery components with enhanced performance and reliability. The present work deals with the introduction of a novel approach of correlating wear with the thermodynamic properties of the system. The approach involves relating wear to thermodynamic entropy flow in the system using the laws of thermodynamics. This relation is verified experimentally and theoretically by considering a sliding contact in a disk-on-disk configuration for two sets of contacting materials namely Bronze …

Mesoscale Simulation Of Grain Boundary Diffusion Creep In The Presence Of Grain Growth, Lucian Zigoneanu

LSU Master's Theses

Grain-boundary (GB) diffusion creep (Coble creep) is the dominant deformation mechanism for the fine-grained materials under low stress and at elevated temperature. During creep deformation the grains become elongated in the tensile direction because of atoms diffusion along GBs from places in compression to those in tension. Consequently, the GB diffusion rate depends on the normal stress gradient along the boundaries. It is widely accepted that the GB migration generally plays two important roles during Coble creep: one leading to the decrease of the creep rate due to the increase of the grain size by GB migration mediated grain growth …