Mechanical Engineering Commons^™

Investigation Of Aluminum Equation Of State Generation, Aaron Ward

Master's Theses (2009 -)

There are many forms and methods to construct equations of state, EOSs. These methods are usually tailored for the particular problem of interest. Here, the EOSs of interest are those used in modeling shock responses. These EOSs cover a wide range of physical characteristics such as detonation and explosions, armor and anti-armor materials, and space structures protection. Aluminum will be the primary focus of this work. Aluminum was chosen because it has been studied in great length in the shock regime and is a common component in shock experiments and space type vehicles.

Effective Approach For Estimating Turbulence-Chemistry Interaction In Hypersonic Turbulent Boundary Layers, L. (Lian) Duan, M. P. Martín

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An effective approach for estimating turbulence-chemistry interaction in hypersonic turbulent boundary layers is proposed, based on "laminar- chemistry" Reynolds-averaged Navier-Stokes mean flow solutions. The approach combines an assumed probability density function with a temperature fluctuation scaling, which provides the second moment for specifying the shape of the probability density function. As a result, the effects of temperature fluctuation on chemical production rates can be estimated without solving an additional moment evolution equation. The validity of this method is demonstrated using direct-numerical-simulation data. This approach can be used to identify regions with potentially significant turbulence-chemistry interaction in hypersonic boundary layers and …

Effectiveness Of Group Kickboxing As A Means To Improve Gait And Balance In Individuals With Ms, Kurt Jackson, Kimberly Edginton Bigelow, Christina Cooper, Harold L. Merriman

Mechanical and Aerospace Engineering Faculty Publications

In recent years, there has been a particular emphasis on identifying and delivering appropriate therapeutic interventions that address the significant balance and gait impairments that affect individuals with multiple sclerosis (MS). Group interventions implemented in community settings have been especially of interest, including tai chi classes. Recently, the authors conducted a preliminary study to examine whether group kick-boxing, which requires more vigorous movements, might be a feasible intervention. Initial findings showed promise and led the authors to pursue a more rigorous follow-up study, with the objective of determining whether a 5-week group kickboxing class improved clinical measures of balance and …

2011 (Fall) Ensi Informer Magazine, Morehead State University. Engineering Sciences Department

ENSI Informer Magazine Archive

The ENSI Informer Magazine published in the fall of 2011.

Thickness-Shear And Thickness-Twist Vibrations Of An At-Cut Quartz Mesa Resonator, Huijing He, Jinxi Liu, Jiashi Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We study thickness-shear and thickness-twist vibrations of an AT-cut quartz plate mesa resonator with stepped thickness. The equations of anisotropic elasticity are used with the omission of the small elastic constant c56. An analytical solution is obtained using Fourier series from which the resonant frequencies, mode shapes, and energy trapping are calculated and examined. The solution shows that a mesa resonator exhibits strong energy trapping of thickness-shear and thickness-twist modes, and that the trapping is sensitive to some of the structural parameters of the resonator.

In Vivo Three-Dimensional Blood Velocity Profile Shapes In The Human Common, Internal, And External Carotid Arteries, Alexey Kamenskiy, Yuris A. Dzenis, Jason N. Mactaggart, Anastasia Desyatova, Iraklis I. Pipinos

Department of Mechanical and Materials Engineering: Faculty Publications

Objective: True understanding of carotid bifurcation pathophysiology requires a detailed knowledge of the hemodynamic conditions within the arteries. Data on carotid artery hemodynamics are usually based on simplified, computer-based, or in vitro experimental models, most of which assume that the velocity profiles are axially symmetric away from the carotid bulb. Modeling accuracy and, more importantly, our understanding of the pathophysiology of carotid bifurcation disease could be considerably improved by more precise knowledge of the in vivo flow properties within the human carotid artery. The purpose of this work was to determine the three-dimensional pulsatile velocity profiles of human carotid arteries. …

Exploration Of Nde Properties Of Amb Supported Rotors For Structural Damage Detection, Jerzy T. Sawicki, Dmitry L. Storozhev, John D. Lekki

Mechanical Engineering Faculty Publications

Recent advancements in actuator technology, power electronics, sensors, and signal processing have created a rapid development of smart machine technologies for rotating machinery. Ranging from machine condition monitoring and diagnostics to full active control of machine behavior, the integration of electrical and computer systems has produced significant advances in machine performance and reliability. Magnetic bearings are a typical mechatronics product. The hardware is composed of mechanical components combined with electronic elements such as sensors and power amplifiers and an information processing part, usually in the form of a microprocessor. In addition, an increasingly important part is software, which specifies the …

A Multi-Regulator Sliding Mode Control Strategy For Output-Constrained Systems, Hanz Richter

Mechanical Engineering Faculty Publications

This paper proposes a multi-regulator control scheme for single-input systems, where the setpoint of a regulated output must be changed under the constraint that a set of minimum-phase outputs remain within prescribed bounds. The strategy is based on a max–min selector system frequently used in the aerospace field. The regulators used for the regulated and limited outputs are of the sliding mode type, where the sliding variable is defined as the difference between an output and its allowable limit. The paper establishes overall asymptotic stability, as well as invariance properties leading to limit protection. The design methodology is illustrated with …

Effect Of Stretch Orientation And Rolling Orientation On The Mechanical Properties Of 2195 Al-Cu-Li Alloy, Omar S. Es-Said, C. J. Parrish, C. A. Bradberry, J. Y. Hassoun, R. A. Parish, A. Nash, N. C. Smythe, K. N. Tran, T. Ruperto, E. W. Lee, D. Mitchell, C. Vinquist

Mechanical Engineering Faculty Works

Sheets of 2195 aluminum-lithium alloy were solution-treated at 507 A degrees C for 30 min. One set was stretched to 3-5% in the 0A degrees, 45A degrees, and 90A degrees angle with respect to the original rolling direction. Two other sets were rolled 6% reduction in thickness and 24% reduction in thickness in the 0A degrees, 45A degrees, and 90A degrees angle with respect to the original rolling direction. All specimens were aged at 143 A degrees C for 36 h. A second group of samples was rolled at 24 and 50% reduction in thickness after a solution treatment of …

Rational Efficiency Of A Heat Exchanger, Jim Mcgovern, Brian P. Smyth

Articles

The authors propose a new and unique definition for the rational efficiency of a heat exchanger. This new rational efficiency is defined in terms of its sub-rational efficiencies: a heat transfer rational efficiency and a friction rational efficiency for each of the fluid systems comprising the heat exchanger. The heat transfer rational efficiency is based on the definition of a mean temperature for the heat source and a mean temperature for the heat sink and reflects the exergy supplied and the exergy received, due to heat transfer only. The friction rational efficiency for each fluid system of the heat exchanger …

Investigating Polymer-Tool Steel Interfaces To Predict The Work Of Adhesion For Demoulding Force Optimisation, Kevin Delaney, David Kennedy, Giuliano Bissacco

Conference Papers

Demoulding parts from replication tools is a critical stage of replication processes such as injection moulding and hot embossing. This challenge increases as part size decreases since components and associated replication cores become more fragile and liable to damage. Understanding interfacial characteristics between a polymer and the tool surface is critical to optimise the demoulding of such parts from replication tools. The strength of the polymer-tool interaction is characterised by the adhesion energy and is specific for a particular polymer-tool pair. It’s magnitude depends upon the tool material, the chemical structure of the polymer, the processing conditions and the surface …

Inverted Pendulum Swing Up Controller, David Kennedy, James Conlon

Conference Papers

The inverted pendulum is a classic control problem. The system is open – loop unstable and continuously wants to reach equilibrium by falling over. The system must be stabilised by means of feedback. The developed inverted pendulum system is shown in Figure 1.

In order to balance the pendulum in the inverted position the pivot must be moved continuously to correct the falling pendulum. This is similar to trying to vertically balance a broom on your hand. This interesting control problem is fundamentally the same as those involved in rocket or missile propulsion. The rocket has to balance on its …

Performance Analysis Of Solar Walls In Minnesota: Final Project Report, Patrick A. Tebbe, Saeed Moaveni, Louis Schwartzkopf

Mechanical and Civil Engineering Department Publications

A study of unglazed transpired solar collectors (referred to as solar walls for this report), has been undertaken. Several installations in the Twin Cities, MN region have been identified, researched, and studied. A combination of weather stations, data logging systems, and building energy management systems were used to collect experimental data on four buildings. Performance calculations were then performed for these buildings and compared with various performance/modeling tools.

Comparison Of Computational And Experimental Aerodynamics: Results For A Wmu Solar Car Model, Yang Yang, William W. Liou

The Hilltop Review

Three-dimensional numerical simulations using FLUENT [1] were performed to model the airflow over the Sunseeker, an award-winning solar car that was designed and built at Western Michigan University. Converged numerical solutions on three different grids are reported and compared with the available experimental data, which include the lift and the drag coefficients. Also reported are the results obtained by using the second-order upwinding discretization on one of the grids. The comparison shows that the computed lift coefficients agree well with the experimental data for all the three grids and the different orders of numerical methods, indicating that the pressure field …

Toward The Design Of A Statically Balanced Fully Compliant Joint For Use In Haptic Interfaces, Levi Clifford Leishman

Theses and Dissertations

Haptic interfaces are robotic force-feedback devices that give the user a sense of touch as they interact with virtual or remote environments. These interfaces act as input devices, mapping the 3-dimensional (3D) motions of the user's hand into 3D motions in a slave system or simulated virtual world. A major challenge in haptic interfaces is ensuring that the user's experience is a realistic depiction of the simulated environment. This requires the interface's design to be such that it does not hinder the user's ability to feel the forces present in the environment. This "transparency" is achieved by minimizing the device's …

Microstructure Evolution In 304l Stainless Steel Subjected To Hot Torsion At Elevated Temperature, Jian Lu

Theses and Dissertations

The current study focus on investigating a relationship between processing variables and microstructure evolution mechanism in 304L stainless steel subjected to hot torsion. The Gleeble 3800 with Mobile Torsion Unit (MTU) is utilized in the current study to conduct hot torsion test of 304L stainless steel. Samples are rotated at 1100℃ in the shear strain rate range of 0.02s-1 to 4.70s-1 and the shear strain range of 0.5 to 4. Orientation imaging microscopy (OIM) technique is used to collect and analyze the microstructure. At low strains (≤1) and strain rate (0.02s-1), average grain size remains relatively constant, but the lengths …

Pandaa: Physical Arrangement Detection Of Networked Devices Through Ambient-Sound Awareness, Zheng Sun, Aveek Purohit, Kaifei Chen, Shijia Pan, Trevor Pering, Pei Zhang

Zheng Sun

Future ubiquitous home environments can contain 10s or 100s of devices. Ubiquitous services running on these devices (i.e. localizing users, routing, security algorithms) will commonly require an accurate location of each device. In order to obtain these locations, existing techniques require either a manual survey, active sound sources, or estimation using wireless radios. These techniques, however, need additional hardware capabilities and are intrusive to the user. Non-intrusive, automatic localization of ubiquitous computing devices in the home has the potential to greatly facilitate device deployments.

This paper presents the PANDAA system, a zero-configuration spatial localization system for networked devices based on …

Pandaa: Physical Arrangement Detection Of Networked Devices Through Ambient-Sound Awareness, Zheng Sun, Aveek Purohit, Kaifei Chen, Shijia Pan, Trevor Pering, Pei Zhang

Aveek Purohit

Future ubiquitous home environments can contain 10s or 100s of devices. Ubiquitous services running on these devices (i.e. localizing users, routing, security algorithms) will commonly require an accurate location of each device. In order to obtain these locations, existing techniques require either a manual survey, active sound sources, or estimation using wireless radios. These techniques, however, need additional hardware capabilities and are intrusive to the user. Non-intrusive, automatic localization of ubiquitous computing devices in the home has the potential to greatly facilitate device deployments.

This paper presents the PANDAA system, a zero-configuration spatial localization system for networked devices based on …

Vortex Shedding From Elongated Bluff Bodies, Zachary J. Taylor

Electronic Thesis and Dissertation Repository

As the spans of suspension bridges increase, the structures become inherently flexible. The flexibility of these structures, combined with the wind and particular aerodynamics, can lead to significant motions. From the collapse due to flutter of the Tacoma Narrows Bridge to the case of vortex-induced vibrations (VIV) of the Storebælt Bridge, it is evident that a better understanding of the aerodynamics of these geometries is necessary. The work herein is motivated by these two problems and is presented in two parts.

In the first part, the focus is on the physical mechanisms of vortex shedding. It is shown that the …

Semiconducting Nanowire Solar Cells For Enhanced Energy Harvesting, Dong Rip Kim

Link Foundation Energy Fellowship Reports

Solar cells are attractive candidates for generating clean and renewable energy. Nanowires (NWs) due to their unique electrical and optical properties offer new opportunities to solar cells for reduced cost and improved efficiency. Although SiNWs have been already demonstrated as promising solar cell elements1 , to harness the full potential of SiNWs, SiNW solar cells require further characterizations and optimizations, including device integrations of SiNWs and surface treatments of SiNWs. Herein we report three main research results to characterize and optimize the performance of SiNW solar cells: 1) single and tandem axial p-i-n SiNW solar cells, 2) direct growth of …