Mechanical Engineering Commons^™

Computational Models Of Thermal Cycling In Chemical Systems, Carl Barratt, Dante Lepore, Matthew Cherubini, Pauline Schwartz

Mechanical and Industrial Engineering Faculty Publications

Computational models of chemical systems provide clues to counterintuitive interactions and insights for new applications. We have been investigating models of chemical reaction systems under forced, thermal cycling conditions and have found that some hypothetical processes generate higher yields under thermal cycling than under single, fixed temperature conditions. A simple kinetic model of an actual process, the two-temperature polymerase chain reaction that replicates DNA, is used to simulate the important features of a chemical system operating under thermal cycling. This model provides insights into the design of other chemical systems that may have important applications in chemistry, biochemistry and chemical …

Numerical Investigation Of Mechanical Durability In Polymer Electrolyte Membrane Fuel Cells, Ahmet Kusoglu, Michael H. Santare, Anette M. Karlsson, Simon Cleghorn, William B. Johnson

Mechanical Engineering Faculty Publications

The relationship between the mechanical behavior and water transport in the membrane electrode assembly (MEA) is numerically investigated. Swelling plays a key role in the mechanical response of the MEA during fuel cell operation because swelling can be directly linked to the development of stresses. Thus, in the model introduced here, the stresses and the water distribution are coupled. Two membranes are studied: unreinforced perfluorosulfonic acid (PFSA) and an experimental reinforced composite membrane. The results suggest that open-circuit voltage operations lead to a uniform distribution of stresses and plastic deformation, whereas under current-load operation, the stresses and the plastic deformation …

Automation Of Cad Model Based Assembly Simulations Using Motion Capture, Anup Madhav Vader

Masters Theses

"The manufacturing industry often uses text and video as a supplement for worker training procedures. Unfortunately, text is often difficult to follow and video lends itself to occlusion issues. CAD based animations of assembly operations can overcome these shortcomings while offering greater potential for operations analysis and simulation flexibility. However, creating such CAD based training simulations manually is a time intensive task and many a times fail to reveal the practical assembly issues faced in the real world. Thus, it is highly beneficial to be able to automate these simulations using motion capture from a physical environment. This thesis research …

Neural Mrac Based On Modified State Observer, Yang Yang

Masters Theses

"A new model reference adaptive control design method with guaranteed transient performance using neural networks is proposed in this thesis. With this method, stable tracking of a desired trajectory is realized for nonlinear system with uncertainty, and modified state observer structure is designed to enable desired transient performance with large adaptive gain and at the same time avoid high frequency oscillation. The neural network adaption rule is derived using Lyapunov theory, which guarantees stability of error dynamics and boundedness of neural network weights, and a soft switching sliding mode modification is added in order to adjust tracking error. The proposed …

Finite Element Modeling Of Bird Strikes And Parametric Evaluation Using Design Of Experiments (Doe), Venkata Varaha Raja Naga Prathyush Bheem Reddy

Masters Theses

"One of the major threats to Aviation industry is the in-flight impact of birds. Aircraft windshields are intensively vulnerable to damage and hence need a certification requirement for a proven level of impact resistance. Bird strike experiments are very expensive and henceforth explicit numerical modeling techniques have grown importance. This compilation mainly relies on the theory of hydrodynamic impact and addresses basic shockwave equations. A smooth particle hydrodynamics based approach is chosen and the numerical simulation is carried out using contact-impact coupling algorithm. The simulation is run using the nonlinear explicit finite element code LSDYNA ver.971, developed by Lawrence Livermore …

Climate And More Sustainable Cities: Climate Information For Improved Planning And Management Of Cities (Producers/Capabilities Perspective), C.S.B. Grimmond, Matthias Roth, Tim R. Oke, Y. C. Au, M. Best, R. Betts, Gregory R. Carmichael, Helen Cleugh, Walter F. Dabberdt, Rohinton Emmanuel, E. Freitas, K. Fortuniak, Steven Hanna, Petra M. Klein, Laurence S. Kalkstein, C. H. Liu, Alex Nickson, David Pearlmutter, David J. Sailor, James Voogt

Mechanical and Materials Engineering Faculty Publications and Presentations

In the last two decades substantial advances have been made in the understanding of the scientific basis of urban climates. These are reviewed here with attention to sustainability of cities, applications that use climate information, and scientific understanding in relation to measurements and modelling. Consideration is given from street (micro) scale to neighbourhood (local) to city and region (meso) scale. Those areas where improvements are needed in the next decade to ensure more sustainable cities are identified. High-priority recommendations are made in the following six strategic areas: observations, data, understanding, modelling, tools and education. These include the need for more …

Effect Of Electrical Double Layer On Electric Conductivity And Pressure Drop In A Pressure-Driven Microchannel Flow, Heng Ban, Bochuan Lin, Zhourui Song

Mechanical and Aerospace Engineering Faculty Publications

The effect of an electrical double layer (EDL) on microchannel flow has been studied widely, and a constant bulk electric conductivity is often used in calculations of flow rate or pressure drop. In our experimental study of pressure-driven micropipette flows, the pipette diameter is on the same order of magnitude as the Debye length. The overlapping EDL resulted in a much higher electric conductivity, lower streaming potential, and lower electroviscous effect. To elucidate the effect of overlapping EDL, this paper developed a simple model for water flow without salts or dissolved gases (such as CO₂) inside a two-dimensional …

An Analytical Model For Rotator Cuff Repairs, A. Aurora, Jorge E. Gatica, Antonie J. Van Den Bogert, J. A. Mccarron, Kathleen A. Derwin

Mechanical Engineering Faculty Publications

Background

Currently, natural and synthetic scaffolds are being explored as augmentation devices for rotator cuff repair. When used in this manner, these devices are believed to offer some degree of load sharing; however, no studies have quantified this effect. Furthermore, the manner in which loads on an augmented rotator cuff repair are distributed among the various components of the repair is not known, nor is the relative biomechanical importance of each component. The objectives of this study are to (1) develop quasi-static analytical models of simplified rotator cuff repairs, (2) validate the models, and (3) predict the degree of load …

Applications Of Pattern Classification To Time-Domain Signals, Crystal Ann Bertoncini

Dissertations, Theses, and Masters Projects

Many different kinds of physics are used in sensors that produce time-domain signals, such as ultrasonics, acoustics, seismology, and electromagnetics. The waveforms generated by these sensors are used to measure events or detect flaws in applications ranging from industrial to medical and defense-related domains. Interpreting the signals is challenging because of the complicated physics of the interaction of the fields with the materials and structures under study. often the method of interpreting the signal varies by the application, but automatic detection of events in signals is always useful in order to attain results quickly with less human error. One method …

Computational Study Of Fluid-Valve Interaction Involving Deep Vein Thrombosis, Upendra Parimi

Open Access Theses & Dissertations

The venous valves in veins carry on the important function of eliminating the retrograde (re-verse) flow of blood in veins and help the veins to carry on their work effectively. The abnormal functioning of venous valves can cause deep vein thrombosis (DVT) which is a phenomena caused by clotting in deep veins. The importance of the thesis work lies in understanding the role of blood flow dynamics in Deep Vein Thrombosis (DVT). Elderly People and pregnant women are the ones who are most likely to develop DVT. It was determined from previous studies that women in their postpartum period are …

Analysis Of Wake Vortices Of A Medium Range Twin-Propeller Military Cargo Aircraft Using Statistically Designed Experiments, Burhan Sahin

Mechanical & Aerospace Engineering Theses & Dissertations

An experimental study was initiated to analyze the trajectories of the streamwise vortices behind the wing tip and flap of a medium range and propeller driven twin-engine military cargo aircraft. The model used for the experimental study was a generic, high wing and half model of a propeller driven aircraft and mounted within Old Dominion University's Low Speed Wind Tunnel where the wind tunnel flow speed was set to constant value of 9 m/sec. The main purpose of the study was to reach regression models for the motion and vorticity strength of both vortices under varying factors such as angle …

Influence Of Interactions Between Turbulence And Radiation On Transmissivities In Hypersonic Turbulent Boundary Layers, A. M. Feldick, L. (Lian) Duan, M. F. Modest, M. P. Martín, D. A. Levin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In the current paper, a high-fidelity large eddy simulation solver is coupled to our modified line-by-line radiative transport equation solver to study the effects of absorption turbulence-radiation interations in a hypersonic turbulent boundary layer, representative of the Orion CEV entering Earth's atmosphere, at peak heating condition. The turbulent and radiation fields represent extreme conditions typical of Orion, as the simulated boundary layer represents the region of high turbulence coupled to region of highest incident radiation. A simplification in the calculation of molecular spectra with a single temperature property database in allows for tractable calculation of spectral properties. A comparison of …

Direct Numerical Simulation Of Hypersonic Turbulent Boundary Layers. Part 2. Effect Of Wall Temperature, L. (Lian) Duan, I. Beekman, M. P. Martín

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we perform direct numerical simulation (DNS) of turbulent boundary layers at Mach 5 with the ratio of wall-to-edge temperature T w/T ℘ from 1.0 to 5.4 (Cases M5T1 to M5T5). The influence of wall cooling on Morkovin's scaling, Walz's equation, the standard and modified strong Reynolds analogies, turbulent kinetic energy budgets, compressibility effects and near-wall coherent structures is assessed. We find that many of the scaling relations used to express adiabatic compressible boundary-layer statistics in terms of incompressible boundary layers also hold for non-adiabatic cases. Compressibility effects are enhanced by wall cooling but remain insignificant, and the …

Direct Detection Of No Produced By High-Temperature Surface-Catalyzed Atom Recombination, Dušan A. Pejaković, Jochen Marschall, Lian Duan, Maria P. Martin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The surface-catalytic recombination of oxygen and nitrogen atoms to form nitric oxide was confirmed by the direct detection of product NO molecules, using single-photon laser-induced fluorescence spectroscopy. Experiments were performed from room temperature to 1200 K in a quartz diffusion-tube sidearm reactor enclosed in a high temperature tube furnace. Atomic nitrogen was generated using a microwave discharge, and atomic oxygen was produced via the rapid gas-phase titration reaction N + NO → O + N2. The use of isotopically labeled titration gases 15N16O and 15N18O allowed for the unambiguous identification of nitric oxide produced by the O + N surface …

Simulation Algorithm And Validation Of A Photovoltaic Water Pumping System, I. Odeh, Y. Yohannis, Brian Norton

Articles

A photovoltaic (PV) water pumping system has been modelled using TRNSYS considering a power supply, a direct current (DC)/alternating current (AC) inverter, an AC induction motor, a centrifugal pump, a well, a water storage tank, and an overflow protection device. The model emulates actual pumping head curves, uses numerical methods to determine pump system working points, and includes a storage tank as a component in the system. It simulates PV-powered water pumping systems, constant voltage tracking, voltage frequency modulation, and maximum power point tracking algorithms; variable inverter frequency with variable motor efficiency, variable inverter frequency with constant motor efficiency, and …

A Study Of Friction Testing Methods Applicable To Demoulding Force Prediction For Micro Replicated Parts, Kevin Delaney, David Kennedy, G. Bissacco

Conference Papers

For replication processes to be deemed successful it must be possible to remove the replicated parts from the tool after processing. With decreasing part and feature size the challenge of demoulding replicated parts increases since the resulting parts and replication tooling used are more delicate and can be easily damaged. Predictive demoulding force models can be used to optimise the part, tool and process parameters to maximise the likelihood of success. Developing accurate models for this process requires knowledge of the dominant interfacial contributions to friction and knowledge of the size scale at which the dominant contributions operate together with …

Pvd And Cvd Coatings For The Metal Forming Industry, Simon Montgomery, David Kennedy, Noel O'Dowd

Conference Papers

Metal forming applications are, by their very nature, taxing on the tools and machines used to achieve a finished component. Material degradation and wear is of critical importance in any such operation as a failing in the tool or machine has the potential to cause health hazards and/or significant monetary losses. The wear of material is due to the contact of two opposing surfaces and their subsequent motion relative to each other. It can take many forms some examples of which are: a two or three body abrasive type, a rolling fatigue type or an adhesion type.

Much research has …

A Comparison Of Case-Based Reasoning And Regression Analysis Approaches For Cost Uncertainty Modeling, Karan Banga

Masters Theses

"This thesis presents case-based reasoning approach for estimating the cost and modeling cost uncertainty of a new product in the concept selection stage. Case-based reasoning (CBR) is an approach which uses old cases/experiences to understand and solve new problems. The CBR approach consists of creating a knowledge-base (or database) containing past cases (products), defining a new case (concept), retrieving cases similar to the new case, and adjusting the solution of the retrieved cases to the new case. The first paper compares case-based reasoning, in studying the effects of varying design attribute specifications on cost estimation accuracy and cost distribution reliability. …

Integration And Characterization Of An Electrical Storage System For A Hydrogen Fuel Cell Plug-In Hybrid Electric Vehicle, Edward Alexei Anculle Arauco

Masters Theses

"Hydrogen fuel cell hybrid vehicles are an advance technology that promises to solve the energy crisis in transportation and green houses emissions. Even more, Plug-in or extended range vehicles can add diversity in energy sources. Extended range vehicles have the capability to extract energy from the grid and hence reduce the cost of operation of the vehicle. EcoCAR: the NeXt Challenge is a Noth [sic] American competition with seventeen schools participating across North America. Missouri S&T is developing a Fuel Cell Plug-in Hybrid electric vehicle which has a large lithium-ion battery able to store 16 kWh. The fuel cell powertrain …

A Real-Time Visualization Of An/Pss-14 Audio Alert Signals For Land Mine Detection Validation, Nitin Kolekar

Masters Theses

"The central idea of the current research is visualization of audio alerts from AN/PSS-14. A visualization device connected to the arm of PSS-14 will show real-time display of MD and GPR Audio Alert signals from PSS-14. This visualization device displays both amplitude-time and spectral frequency-time formats of the signals. The latter format achieves visual separation of combined, simultaneous, MD and GPR alerts. The joint occurrence of MD and GPR signals in a specific time window confirms the presence of landmine. This window is defined by the time of occurrence of MD peak and time of occurrence GPR diffraction from onset …