Engineering Commons^™

Mechanical Properties Of The Intervertebral Disc As An Estimator Of Postmortem Interval, Jennifer Noelle Jackson

Electronic Theses and Dissertations

Currently, forensic scientists are only able to determine time since death (or postmortem interval) up to the first 60 hours. This is based largely on insect activity. Herein, it is proposed to use the degradation of the intervertebral disc (IVD) after death to determine a relationship between the mechanical properties of cadaveric tissue and time since death in order to extend the 60-hour window. To that end, 1 fresh human spine and 6 pig spines were each separated into sections (6 human and 48 pig), with each section having one intact disc. The sections were buried, unearthed, and cleaned, leaving …

Correlation Of Acoustic Emission Parameters With Weight And Velocity Of Moving Vehicles, Amar Kolgaonkar

Electronic Theses and Dissertations

The thesis is motivated by the goal of doing initial investigation and experimentation for the development of Weigh-in-Motion (WIM) system using acoustic emission phenomenon. A great deal of research is going on for measuring the weight of moving vehicles. Weigh-in-motion of commercial vehicles is essential for management of freight traffic, highway infrastructure design and maintenance, and monitoring of heavy weight vehicles. The research work presents a methodology for correlating the weight of a moving vehicle with acoustic emission parameters (such as counts and energy). Furthermore, the correlation between the speed of vehicle with the acoustic emission parameters is developed. Preliminary …

Uv-Liga Compatible Electroformed Nano-Structured Materials For Micro Mechanical Systems, Bo Li

Electronic Theses and Dissertations

UV-LIGA is a microfabrication process realzed by material deposition through microfabricated molds. UV photolithography is conducted to pattern precise thick micro molds using UV light sensitive materials, mostly SU-8, and electroforming is performed to fabricate micro metallic structures defined by the micro molds. Therefore, UV-LIGA is a bottom-up in situ material-addition process. UV-LIGA has received broad attention recently than LIGA – a micro molding fabrication process using X-ray to pattern the micro molds. LIGA is an expansive and is limited in access. In comparing to LIGA, the UV-LIGA is a cost effective process, and is widely accessible and safe. Therefore, …

Adhesion Of An Axisymmetric Film Onto A Rigid Substrate: Application To A Mem-Rf-Switch, Ming-Fung Wong

Opportunities for Undergraduate Research Experience Program (OURE)

A solid mechanics model is constructed to discuss the mechanical aspect of a MEM-RF-switch. A thin circular membrane clamped at the perimeter is adhered to a rigid cylindrical flat punch. A tensile load applied to the punch causes an interfacial de lamination. Once the contact circle shrinks to 0.1758 - 0.3651 of the punch dimension depending on the magnitude of the tensile residual stress on the film, a spontaneous delamination, or "pull-off', occurs and the film snaps from the substrate at a critical load and punch displacement. The theoretical model has significant implications in MEMS that involves active moveable films.

Evaluation Of A Mechanical System For Reconstructing Soil On Surface Mined Land, John P. Fulton, Larry G. Wells

Biosystems and Agricultural Engineering Faculty Publications

The existence of excessive soil compaction has hindered the surface mining industry from returning land to pre−mining productivity after reclamation, especially on prime farmland soils. Heavy earthmoving equipment used during reclamation tends to generate root−limiting bulk densities that adversely affect plant growth thereby decreasing yields. Therefore, the purpose of this study was to evaluate a mechanism, called the ‘Soil Regenerator,’ which reconstructs soil media at minimum bulk density during surface mine reclamation. The prototype soil forming mechanism was mounted on the front of a conventional bulldozer. Soil was placed in long narrow windrows by a scraper or bulldozer. As the …

Vibrational Behavior Of The MN+1AxN Phases From First-Order Raman Scattering (M=Ti,V,Cr, A=Si, X=C,N), Jonathan E. Spanier, Surojit Gupta, Maher S. Amer, Michel W. Barsoum

Mechanical and Materials Engineering Faculty Publications

We report on the Raman spectra of Ti₃SiC₂ (312), M2AlC(211) (M=Ti, V, Cr, and Nb) and Ti4AlN3 (413), as representative compounds from the family of Mn+1AXn phases. Intense and narrow first-order Raman peaks are observed, and we present an analysis of the spectra based on symmetry considerations and from results of first-principles calculations of phonon frequencies. The agreement between experimental and calculated mode energies is excellent. The identification of the modes enables application of Raman scattering as a diagnostic tool for the detailed study of the structural and physical properties of this family of compounds and their …

Dynamic Re-Optimization Of A Mems Controller In Presence Of Unmodeled Uncertainties, Nishant Unnikrishnan, S. N. Balakrishnan, Venkat Durbha

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Online trained neural networks have become popular in recent years in designing robust and adaptive controllers for dynamic systems with uncertainties in their system equations because of their universal function approximation property. This paper discusses a technique that dynamically reoptimizes a Single Network Adaptive Critic (SNAC) based optimal controller in the presence of unmodeled uncertainties. The controller design is carried out in two steps: (i) synthesis of a set of online neural networks that capture the uncertainties in the plant equations on-line (ii) re-optimization of the existing optimal controller to drive the states of the plant to a desired reference …

A Model Of Function-Based Representations, Michael Van Wie, Cari R. Bryant, Matt R. Bohm, Robert B. Stone, Daniel A. Mcadams

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The need to model and to reason about design alternatives throughout the design process demands robust representation schemes of function, behavior, and structure. Function describes the physical effect imposed on an energy or material flow by a design entity without regard for the working principles or physical solutions used to accomplish this effect. Behaviors are the physical events associated with a physical artifact (or hypothesized concept) over time (or simulated time) as perceived by an observer. Structure, the most tangible concept, partitions an artifact into meaningful constituents such as features, Wirk elements, and interfaces in addition to the widely used …

Intelligent Sensors: An Integrated Systems Approach, Ajay Mahajan, Sanjeevi Chitikeshi, Pavan Bandhil, Lucas Utterback, Fernando Figueroa

Mechanical Engineering Faculty Research

The need for intelligent sensors as a critical component for Integrated System Health Management (ISHM) is fairly well recognized by now. Even the definition of what constitutes an intelligent sensor (or smart sensor) is well documented and stems from an intuitive desire to get the best quality measurement data that forms the basis of any complex health monitoring and/or management system. If the sensors, i.e. the elements closest to the measurand, are unreliable then the whole system works with a tremendous handicap. Hence, there has always been a desire to distribute intelligence down to the sensor level, and give it …

Physical Intelligent Sensors, Pavan Bandhil, Sanjeevi Chitikeshi, Ajay Mohan Mahajan, Fernando Figueroa

Mechanical Engineering Faculty Research

This paper proposes the development of intelligent sensors as part of an integrated systems approach, i.e. one treats the sensors as a complete system with its own sensing hardware (the traditional sensor), A/D converters, processing and storage capabilities, software drivers, self-assessment algorithms, communication protocols and evolutionary methodologies that allow them to get better with time. Under a project being undertaken at the NASA s Stennis Space Center, an integrated framework is being developed for the intelligent monitoring of smart elements. These smart elements can be sensors, actuators or other devices. The immediate application is the monitoring of the rocket test …

Test 1841: Kubota M120dt Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1858: Mccormick Mtx 150 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Nebraska Summary 540: Agco Dt180a Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Laser Induced Fluorescence Photobleaching Anemometer For Microfluidic Devices, Guiren Wang

Faculty Publications

We have developed a novel, non-intrusive fluid velocity measurement method based on photobleaching of a fluorescent dye for microfluidic devices. The residence time of thefluorescent dye in a laser beam depends on the flow velocity and approximately corresponds to the decaying time of the photobleaching of the dye in the laser beam. The residence time is inversely proportional to the flow velocity. The fluorescence intensity increases with the flow velocity due to the decrease of the residence time. A calibration curve between fluorescence intensity and known flow velocity should be obtained first. The calibration relationship is then used to calculate …

Numerical Analysis Of Heat Transfer In Pulsating Turbulent Flow In A Pipe, Xuefeng Wang, Nengli Zhang

Department of Mechanical and Materials Engineering: Faculty Publications

Convection heat transfer in pulsating turbulent flow with large velocity oscillating amplitudes in a pipe at constant wall temperature is numerically studied. A low-Reynolds-number (LRN) k–ε turbulent model is used in the turbulence modeling. The model analysis indicates that Womersley number is a very important parameter in the study of pulsating flow and heat transfer. Flow and heat transfer in a wide range of process parameters are investigated to reveal the velocity and temperature characteristics of the flow. The numerical calculation results show that in a pulsating turbulent flow there is an optimum Womersley number at which heat transfer is …

Advances In In-Situ Calibration Of Attitude And Doppler Sensors For Precision Oceanographic Submersible Navigation, James C. Kinsey

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

This paper reviews the development and experimental evaluation of three techniques for estimating the alignment matrix of Doppler sonars, which are commonly used for precision navigation of oceanographic submersibles, employing sensors commonly employed aboard these vehicles. Most previously reported methods addressed the problem of single degree of freedom alignment using bottom-lock Doppler sonar data and global positioning system (GPS) navigation data. This paper reviews three techniques for three degree of freedom calibration of attitude and Doppler sonar sensors, using sensor data available to vehicles at full ocean depth. The first technique provides a general linear least-square estimate of the alignment …

Test 2333: Challenger Mt555b Techstar Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Stochastic Optimal Control With Neural Networks And Application To A Retailer Inventory Problem, Zhongwu Huang, Xiaohua Wang, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Overwhelming computational requirements of classical dynamic programming algorithms render them inapplicable to most practical stochastic problems. To overcome this problem a neural network based Dynamic Programming (DP) approach is described in this study. The cost function which is critical in a dynamic programming formulation is approximated by a neural network according to some designed weight-update rule based on Temporal Difference(TD)learning. A Lyapunov based theory is developed to guarantee an upper error bound between the output of the cost neural network and the true cost. We illustrate this approach through a retailer inventory problem.

Heat Transfer Model For The Ignition Of Metal Powder On A Heated Filament, Trent Stanton Ward

Theses

The thermal processes leading to ignition of metal powders in environments that experience rapid temperature changes are currently poorly understood. In this research, a methodology for studying and quantification of such processes is developed. In the experimental case study, the ignition temperature of Mg powder coated on the surface of an electrically heated filament is detected optically at different heating rates. To interpret the results, a heat transfer model has been developed for a multilayer powder coating on top of an electrically heated filament. The coating is modeled using a hexagonal close packed geometry and the heat transfer equations are …

Test 1846: Challenger Mt765b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1859: Challenger Mt755b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1860: Challenger Mt835b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1861: Challenger Mt845b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1847: Challenger Mt865b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Unsteady Tip Leakage, Bow Shock, Igv Wake Interaction In A Compressor, Xuedong Zhou, J. Mitch Wolff

Mechanical and Materials Engineering Faculty Publications

Unsteady aerodynamic analysis of Inlet Guide Vane (IGV)/rotor interaction is conducted with a commercial CFD solver, STAR-CD. 12% and 26% IGV axial chord IGV/Rotor spacing configurations were examined for 100% corrected speed at choke, peak efficiency and near stall conditions to investigate bow shock/tip leakage interaction within blade rows. Comparison with IGV surface unsteady pressure experimental data indicates good agreement at the IGV trailing edge across the span for both spacing configurations; therefore, validating the modeling of the high speed, highly loaded transonic compressor. The strongest effect on the tip clearance flow physics was caused by decreasing the axial spacing. …

Test 1879: Challenger Mt875b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Nebraska Summary 546: Massey Ferguson 8460 Diesel Dyna-Step Transmission, 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 543: Dt240a Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Nebraska Tractor Test 1849: Agco Gt55a Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Nebraska Tractor Test 1850: Agco Gt75a Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.