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The Effects Of Solvent Mixture On The Thermal And Mechanical Properties Of Solvent Cast Poly-Lactic Acid (Pla) Film, Jeremy Hughes 2011 Clemson University

The Effects Of Solvent Mixture On The Thermal And Mechanical Properties Of Solvent Cast Poly-Lactic Acid (Pla) Film, Jeremy Hughes

All Theses

CH 1 ABSTRACT
The objective of this study was to investigate the effects of various solvents on the crystallinity and thermal expansion stability of PLA film. Three different PLA films were produced by the solvent casting technique; PLA in chloroform (PLA-C), PLA in methylene chloride (PLA-M), and PLA in methylene chloride: acetonitrile = 50: 50 (PLA-MA). The PLA-MA had higher % crystallinity, 46.15, than the PLA-C, 24.03, and the PLA-M, 14.25. With this increase in crystallinity, the PLA-MA had improved thermal expansion stability as shown by very low accumulated dimensional changes at 20-100 ¡C. Wide angle x-ray diffraction identified ...


Development Of A Structured Concrete Thermocline Thermal Energy Storage System, Bradley M. Brown 2011 University of Arkansas, Fayetteville

Development Of A Structured Concrete Thermocline Thermal Energy Storage System, Bradley M. Brown

Theses and Dissertations

The past couple of decades have shown a concern when considering the way the world obtains its power. The focus has been switching from fossil fuels that have been used for hundreds of years to renewable energy sources, such as the sun. Solar energy is readily and infinitely available for harnessing. One problem with solar energy, though, is its inability to be used during the night time and during cloud covered weather. A solution to this problem is the use of energy storage mechanisms. For solar plants that use solar thermal energy (concentrating solar power plants), thermal energy storage (TES ...


In-Situ Ellipsometry Characterization Of Anodically Grown Silicon Dioxide And Lithium Intercalation Into Silicon, Eric A. Montgomery 2011 University of Nebraska-Lincoln

In-Situ Ellipsometry Characterization Of Anodically Grown Silicon Dioxide And Lithium Intercalation Into Silicon, Eric A. Montgomery

Theses, Dissertations, and Student Research from Electrical & Computer Engineering

In this thesis, in-situ ellipsometry and electroanalytical investigations of two electrochemical processes are reported: including the formation of anodically grown silicon dioxide and the intercalation of lithium into silicon. Analysis of the ellipsometry data shows that the anodically grown silicon dioxide layer is uniform and has similar properties as thermally grown silicon dioxide. The lithium-ion intercalation data reveals non-uniform thin film formation, which requires further studies and development of appropriate ellipsometric optical models.

Advisers: Eva Schubert and Mathias Schubert


Relationship Between Impact Energy And Fracture Toughness Of Prestressed Concrete Railway Sleepers, Sakdirat Kaewunruen, Alexander Remennikov 2011 RailCorp

Relationship Between Impact Energy And Fracture Toughness Of Prestressed Concrete Railway Sleepers, Sakdirat Kaewunruen, Alexander Remennikov

Alex Remennikov

The prestressed concrete sleepers (or railroad ties), which are installed in railway track systems as the crosstie beam support, are designed to carry and transfer the wheel loads from the rails to the ground. It is well known that railway tracks are subject to impact loading conditions, which are attributable to the train operations with either wheel or rail abnormalities such as flat wheels, dipped rails, etc. These loads are of very high magnitude but short duration. In addition, there exists the potential of repeated load experience during the design life of prestressed concrete sleepers. Prestressed concrete has played a ...


Dynamic Design Guidelines For Prestressed Concrete Sleepers, Alexander Remennikov, Martin H. Murray, Sakdirat Kaewunruen 2011 University of Wollongong

Dynamic Design Guidelines For Prestressed Concrete Sleepers, Alexander Remennikov, Martin H. Murray, Sakdirat Kaewunruen

Alex Remennikov

Current design philosophy, outlined in AS 1085.14, is based on the analysis of permissible stresses resulting from quasi-static wheel loads and essentially the static response of concrete sleepers. In general, cracking can incur when the bottom fibre stress is larger than tensile strength of concrete. Premature cracking of prestressed concrete sleepers has been detected in railway tracks. The major cause of cracking is the infrequent but high-magnitude wheel loads produced by a small percentage of “out-of-round” wheels or railhead surface defects, which are crudely accounted for in AS 1085.14 by a single load factor. Based on the current ...


Dc Pulsed Atmospheric Pressure Plasma Jet Image Information, Denis P. Dowling, F T. O'Neill, Vladimir Milosavljevic, Victor J. Law 2011 University College Dublin

Dc Pulsed Atmospheric Pressure Plasma Jet Image Information, Denis P. Dowling, F T. O'Neill, Vladimir Milosavljevic, Victor J. Law

Articles

This paper presents optical imaging and optical emission spectroscopy (OES) data of an atmospheric-pressure plasma jet. It is shown how the visual information and OES information of the air discharge are related as the blown arc extends from the nozzle (2-4 mm) with a molecular nitrogen rotational temperature on the order of 1700 K and the flowing afterglow beyond this region is dominated by the cooler (300-K) NO-O chemiluminescent reaction that produces NO2 species.


Thickness-Shear And Thickness-Twist Vibrations Of An At-Cut Quartz Mesa Resonator, Huijing He, Jinxi Liu, Jiashi Yang 2011 University of Nebraska-Lincoln

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

Mechanical & 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 2011 University of Nebraska Medical Center

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

Mechanical & 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 ...


Construction Of The Next Generation Of Energy Efficient Light Boxes - Sponsored By Bayer Environmental Science, Gregory Keith Bartley Jr. 2011 University of Tennessee, Knoxville

Construction Of The Next Generation Of Energy Efficient Light Boxes - Sponsored By Bayer Environmental Science, Gregory Keith Bartley Jr.

Gregory Keith Bartley Jr.

This short presentation includes an overview of features that went into constructing a new type of light box technology utilizing low-power usage LEDs and Low Density flexible Polymers. This light box was constructed for digital image analysis of plant health and ground cover using a Canon Powershot G12 camera and Sigma Scan Digital Image Analysis Software.


Electronic And Magnetic Excitations In Graphene And Magnetic Nano-Ribbons, Maher Zakaria Ahmed Selim 2011 The University of Western Ontario

Electronic And Magnetic Excitations In Graphene And Magnetic Nano-Ribbons, Maher Zakaria Ahmed Selim

Electronic Thesis and Dissertation Repository

The discovery of graphene - a 2D material with superior physical properties - in 2004 was important for the intensive global research to find alternatives to three-dimensional (3D) semiconductor materials in industry. At the same time there have been exciting advances for 2D magnetic materials on the nanometer scale. The superior properties of graphene are mainly attributed to its crystal structure and its relatively short-range interactions. These properties show that natural and artificial 2D materials are promising for new applications.

In this thesis we have carried out a comprehensive investigation of the effects of the 2D lattice structures, the roles of nearest ...


Two-Scale Microstructure Dynamics, Arkadi Berezovski, Mihhail Berezovski, Juri Engelbrecht 2011 Tallinn University of Technology

Two-Scale Microstructure Dynamics, Arkadi Berezovski, Mihhail Berezovski, Juri Engelbrecht

Publications

Wave propagation in materials with embedded two different microstructures is considered. Each microstructure is characterized by its own length scale. The dual internal variables approach is adopted yielding in a Mindlin-type model including both microstructures. Equations of motion for microstructures are coupled with the balance of linear momentum for the macromotion, but not coupled with each other. Corresponding dispersion curves are provided and scale separation is pointed out.


Vibration-Based Health Monitoring Of Multiple-Stage Gear Train And Differential Planetary Transmission Involving Teeth Damage And Backlash Nonlinearity, Andrew Patrick Sommer 2011 California Polytechnic State University - San Luis Obispo

Vibration-Based Health Monitoring Of Multiple-Stage Gear Train And Differential Planetary Transmission Involving Teeth Damage And Backlash Nonlinearity, Andrew Patrick Sommer

Master's Theses and Project Reports

The objective of this thesis is to develop vibration-based fault detection strategies for on-line condition monitoring of gear transmission systems. The study divides the thesis into three sections. First of all, the local stresses created by a root fatigue crack on a pinion spur gear are analyzed using a quasi-static finite element model and non-linear contact mechanics simulation. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. The second section is dedicated to fixed axis power trains. Torsional vibration ...


Coordination Of Multirobot Teams And Groups In Constrained Environments: Models, Abstractions, And Control Policies, Nora Ayanian 2011 University of Pennsylvania

Coordination Of Multirobot Teams And Groups In Constrained Environments: Models, Abstractions, And Control Policies, Nora Ayanian

Publicly Accessible Penn Dissertations

Robots can augment and even replace humans in dangerous environments, such as search and rescue and reconnaissance missions, yet robots used in these situations are largely tele-operated. In most cases, the robots' performance depends on the operator's ability to control and coordinate the robots, resulting in increased response time and poor situational awareness, and hindering multirobot cooperation.

Many factors impede extended autonomy in these situations, including the unique nature of individual tasks, the number of robots needed, the complexity of coordinating heterogeneous robot teams, and the need to operate safely. These factors can be partly addressed by having many ...


Hydrometallurgical Process For Extraction Of Metals From Electronic Waste-Part Ii: Development Of The Processes For The Recovery Of Copper From Printed Circuit Boards (Pcb), Zeljko J. Kamberovic 2011 Faculty of Technology and Metallurgy, University of Belgrade, Serbia

Hydrometallurgical Process For Extraction Of Metals From Electronic Waste-Part Ii: Development Of The Processes For The Recovery Of Copper From Printed Circuit Boards (Pcb), Zeljko J. Kamberovic

Zeljko J Kamberovic

Rapid technological development induces increase of generation of used electric and electronic equipment waste, causing a serious threat to the environment. Waste printed circuit boards (WPCBs), as the main component of the waste, are significant source of base and precious metals, especially copper and gold. In recent years, most of the activities on the recovery of base and precious metals from waste PCBs are focused on hydrometallurgical techniques as more exact, predictable and easily controlled compared to conventional pyrometallurgical processes. In this research essential aspects of the hydrometallurgical processing of waste of electronic and electrical equipment (WEEE) using sulfuric acid ...


Modeling And Development Of A Mems Device For Pyroelectric Energy Scavenging, Salwa Mostafa 2011 University of Tennessee - Knoxville

Modeling And Development Of A Mems Device For Pyroelectric Energy Scavenging, Salwa Mostafa

Doctoral Dissertations

As the world faces an energy crisis with depleting fossil fuel reserves, alternate energy sources are being researched ever more seriously. In addition to renewable energy sources, energy recycling and energy scavenging technologies are also gaining importance. Technologies are being developed to scavenge energy from ambient sources such as vibration, radio frequency and low grade waste heat, etc. Waste heat is the most common form of wasted energy and is the greatest potential source of energy scavenging.

Pyroelectricity is the property of some materials to change the surface charge distribution with the change in temperature. These materials produce current as ...


The Effect Of Barrier Properties Of Non-Foil Retort Films On Shelf Life Of Oxygen Sensitive Foods, Mahalaxmi Dharman 2011 Clemson University

The Effect Of Barrier Properties Of Non-Foil Retort Films On Shelf Life Of Oxygen Sensitive Foods, Mahalaxmi Dharman

All Theses

A simulated food product sensitive to oxygen, which was a mixture of tomato paste, water, and corn oil (2:2:1), was filled into five different barrier coated pouches, a foil barrier and a low barrier pouch. These pouches were thermally processed at 250¡F for 30 minutes and stored in darkness under accelerated conditions (45±2¡C and 50±2%RH) for up to 180 days.
The simulant was analyzed for lipid oxidation by TBARS and lycopene degradation by colorimetry (L*,a*,b* values and Hue angle). The oxygen permeability (OP) in all the pouches increased by 5 to ...


Effect Of Different Oxygen Barrier Pouches On The Quality Of Retorted Carrots, Sarah Khor 2011 Clemson University

Effect Of Different Oxygen Barrier Pouches On The Quality Of Retorted Carrots, Sarah Khor

All Theses

Thermally processed (TP) baby carrots were packaged in pouches with varying oxygen transmission rate (OTR) pouches. The pouches were four layer laminate (PET-Nylon-Barrier-CPP) with barrier layer being foil, aluminum oxide (AlOx), ethylene vinyl alcohol (EVOH), and nylon. Retort pouches were placed in boxes that were stored in an environmental chamber (43 °C, 50%RH). The objective of the study was to determine an alternative barrier retort pouch that is microwavable and still had similar barrier functions to foil for baby carrots and determine how the alternative compare with regard to shelf life. Instrumental analysis of color (L*, a*, b*) and ...


Cushop: A Simulated Shopping Environment Fostering Consumer-Centric Packaging Design & Testing, Charles Tonkin 2011 Clemson University

Cushop: A Simulated Shopping Environment Fostering Consumer-Centric Packaging Design & Testing, Charles Tonkin

All Dissertations

Consumer product packaging provides product damage protection, extends product shelf life, and communicates product usage instructions to the consumer. Its collective contribution to the waste stream is notorious, but its role in product salability is much less understood. Consumers now make the majority of product purchase decisions while present at the shelf, and since they do it very quickly (within 5-8 seconds), and do not appear to adhere to strong brand loyalty as was once more common, packaging (and more specifically, its aesthetics and contrast with its competitors) plays a dominant role in the decision-making process. It is difficult, however ...


Effects Of Mass Layer Dimension On A Finite Quartz Crystal Microbalance, Y. P. Kong, Jinxi Liu, Huijing He, Jiashi Yang 2011 Shijiazhuang Tiedao University

Effects Of Mass Layer Dimension On A Finite Quartz Crystal Microbalance, Y. P. Kong, Jinxi Liu, Huijing He, Jiashi Yang

Mechanical & Materials Engineering Faculty Publications

In this paper, we investigate free thickness-shear and thickness-twist vibrations of a finite crystal resonator of AT-cut quartz carrying a thin mass layer at the central portion of its top surface operating as a quartz crystal microbalance. 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 vibration confinement by the mass layer are calculated and examined.


Friction Bit Joining Of 5754 Aluminum To Dp980 Ultra-High Strength Steel: A Feasibility Study, Britney Weickum 2011 Brigham Young University - Provo

Friction Bit Joining Of 5754 Aluminum To Dp980 Ultra-High Strength Steel: A Feasibility Study, Britney Weickum

Theses and Dissertations

In this study, the dissimilar metals 5754 aluminum and DP980 ultra-high strength steel were joined using the friction bit joining (FBJ) process. The friction bits were made using one of three steels: 4140, 4340, or H13. Experiments were performed in lap shear, T-peel, and cross tension configurations, with the 0.070" thick 5754 aluminum alloy as the top layer through which the friction bit cut, and the 0.065" thick DP980 as the bottom layer to which the friction bit welded. All experiments were performed using a computer controlled welding machine that was purpose-built and provided by MegaStir Technologies. Through ...


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