Engineering Science and Materials Commons^™

Structure And Properties Of Graphene Nano Disks (Gnd) With And Without Edge-Dopants, Pubodee Ratana-Arsanarom

Dissertations, Master's Theses and Master's Reports - Open

Graphene is one of the most important materials. In this research, the structures and properties of graphene nano disks (GND) with a concentric shape were investigated by Density Functional Theory (DFT) calculations, in which the most effective DFT methods - B3lyp and Pw91pw91 were employed.

It was found that there are two types of edges - Zigzag and Armchair in concentric graphene nano disks (GND). The bond length between armchair-edge carbons is much shorter than that between zigzag-edge carbons. For C24 GND that consists of 24 carbon atoms, only armchair edge with 12 atoms is formed. For a GND larger …

Me-Em 2011 Annual Report, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering Annual Reports

Table of Contents

• ME-EM: 85 Years of Excellence
• Faculty & Staff
• Enrollment & Degrees
• Alumni
• Resources
• Graduates

Technique To Measure Heats Of Reaction Of Ti-B, Al-Ti-B, And Al-Ti-B4c Powder Blends, Andrew H. Baker

Dissertations, Master's Theses and Master's Reports - Open

In this research, a modification to initiation aid ignition in bomb calorimetry that involves systemically blending levels of boron and potassium nitrate initiation aids with a bulk structural energetic elemental power blend is developed. A regression is used to estimate the nominal heat of reaction for the primary reaction. The technique is first applied to the synthesis of TiB2 as a validation study to see if close proximity to literature values can be achieved. The technique is then applied to two systems of interest, Al-Ti-B, and Al-Ti-B4C. In all three investigations, x-ray diffraction is used to characterize the product phases …

Effect Of Fullerene Nano-Spheres On Evaporation Kinetics Of Fluids, Wenhu Wang

Browse all Theses and Dissertations

As the interest in fluid evaporation kinetics keeps increasing, it's inevitably noticed that fullerene nanospheres play an important role on it. In this study, we investigate the C60 nanospheres' effect on the evaporation kinetics and thermal transitions of different solvents (water, chlorobenzene) over the entire range of solubility. According to distinct polarity of different solvent, fullerene solution would behave differently, the trend of increasing in evaporation rate as the concentration increased was observed in aromatic solvents while the rate kept decreasing in water. The result of differential scanning calorimetry (DSC) and Raman spectroscopy provided an evidence about structuring in water …

Simulation Of Electrospun Nanofiber Deposition On Stationary And Moving Substrates, Linhua Liu, Yuris A. Dzenis

Department of Mechanical and Materials Engineering: Faculty Publications

Electrospinning produces continuous fibers with diameters from single nanometers to microns by jetting polymer solutions in high electric fields. Electrospun non-woven filamentary materials attract rapidly growing interest for broad range of applications. Properties of these materials depend on their nano- and microstructure that is determined in turn by the electric field and nanofiber collector. Despite critical importance, deposition of electrospun fibers on substrates has not yet been extensively studied theoretically and new methods of nanofiber collection continue to be developed mostly empirically. The objective of this Letter was to develop and demonstrate numerical simulation of electrospun nanofiber deposition on moving …

Modeling Of Solvent Evaporation From Polymer Jets In Electrospinning, Xiang-Fa Wu, Yury Salkovskiy, Yuris A. Dzenis

Department of Mechanical and Materials Engineering: Faculty Publications

Solvent evaporation plays a critical role in nanofiber formation in electrospinning. Here, we present a nonlinear mass diffusion-transfer model describing the drying process in dilute polymer solution jets. The model is used to predict transient solvent concentration profiles in polyacrylonitrile/ N,N-dimethylformamide (PAN/DMF) jets with the initial radii ranging from 50µm down to 100 nm. Numerical simulations demonstrate high transient inhomogeneity of solvent concentration over the jet cross-section in microscopic jets. The degree of inhomogeneity decreases for finer, submicron jets. The simulated jet drying time decreases rapidly with the decreasing initial jet radius, from seconds for microjets to single milliseconds for …

Preparation And Characterization Of Iron Oxide And Hydroxide Based Nanomaterials, Guillermo Carbajal Franco

Open Access Theses & Dissertations

Iron (Fe) oxides and hydroxides are common and abundant materials. They exhibit diverse crystal structures, properties and phenomena by virtue of which they find a wide range of scientific and technological applications. Controlled growth and manipulation of the specific structure and electronic behavior to meet the requirements of a given application is a challenging problem in view of many possible phases and composition of the resulting materials. The preparation method and experimental conditions will, therefore, significantly affect the properties and performance of Fe oxides and hydroxides. The goal of the project is to obtain Fe-based oxide/hydroxide catalytic materials and to …

Intermediate Layers In Tandem Organic Solar Cells, Yongbo Yuan, Jinsong Huang, Gang Li

Department of Mechanical and Materials Engineering: Faculty Publications

Tandem structures can boost the efficiency of organic solar cell to more than 15%, compared to the 10% limit of single layer bulk heterojunction devices. Design and fabricating of intermediate layers plays a very important role to achieve high device performance. This article will review the main experimental progresses of tandem organic solar cells, and focus on the intermediate layers (charge recombination layers) in both thermal evaporated and solution processed organic tandem solar cell devices.

A Model Of Giant Vacuole Dynamics In Human Schlemm’S Canal Endothelial Cells, Ryan M. Pedrigi, David Simon, Ashley Reed, W. Daniel Stamer, Darryl R. Overby

Department of Mechanical and Materials Engineering: Faculty Publications

Aqueous humour transport across the inner wall endothelium of Schlemm’s canal likely involves flow through giant vacuoles and pores, but the mechanics of how these structures form and how they influence the regulation of intraocular pressure (IOP) are not well understood. In this study, we developed an in vitro model of giant vacuole formation in human Schlemm’s canal endothelial cells (HSCECs) perfused in the basal-to-apical direction (i.e., the direction that flow crosses the inner wall in vivo) under controlled pressure drops (2 or 6 mmHg). The system was mounted on a confocal microscope for time-lapse en face imaging, and cells …

Freeze-Thawing Of Polyester/E-Glass As An Evaluation Of An Astm International Test Standard Proposal, Stefan Mauritz Strandlund

Electronic Theses and Dissertations

American Composites Manufacturers Association (ACMA) reported in 2009 that the four major sectors currently utilizing fiber reinforced polymers (FRP) are construction, corrosion, marine, and transportation in descending order of total FRP shipped. All of these sectors are known to be billion dollar industries and they are all involved with applications subjected to freezing and thawing. FRP encompass many characteristics that are beneficial to these sectors and also in resisting this exposure. ASTM International has yet not developed a standard to test FRP materials resistance to freeze-thaw (FT) cycling exposure. The D20.18.02 committee of the ASTM is in the process of …

Variable Block Size Motion Compensation In The Redundant Wavelet Domain, Ahmed Abdelgadir Suliman

Dissertations

Video is one of the most powerful forms of multimedia because of the extensive information it delivers. Video sequences are highly correlated both temporally and spatially, a fact which makes the compression of video possible. Modern video systems employ motion estimation and motion compensation (ME/MC) to de-correlate a video sequence temporally. ME/MC forms a prediction of the current frame using the frames which have been already encoded. Consequently, one needs to transmit the corresponding residual image instead of the original frame, as well as a set of motion vectors which describe the scene motion as observed at the encoder. The …

Solving The Partial Differential Equation Of Vibrations With Interval Parameters Using The Interval Finite Difference Method, Brenda G. Medina

Open Access Theses & Dissertations

Accuracy and efficiency are among the main factors that drive today's innovative disciplines. As technology rapidly advances, efficiency takes on new meanings but what about accuracy? How accurate is accurate? Human error, uncertainties in measurement, and rounding errors are just some causes of inaccuracy. Interval Computations is an area that allows for such issues to be taken into account; for each measurement attained (for example), an interval can be built by considering the error associated with the measurement, and such an interval can be utilized in the mathematical computations of interest.

We consider the partial differential equation (PDE) of vibrations …

Calibration Of Alumina-Epoxy Nanocomposites Using Piezospectroscopy For The Development Of Stress-Sensing Adhesives, Amanda L. Stevenson

Electronic Theses and Dissertations

A non-invasive method to quantify the stress distribution in polymer-based materials is presented through the piezospectroscopic calibration of alumina-epoxy nanocomposites. Three different alumina volume fraction nanocomposites were created and loaded under uniaxial compression in order to determine the relationship between applied stress and the frequency shift of the R-lines produced by alumina under excitation. Quantitative values for six piezospectroscopic coefficients were obtained which represent the stress-sensing property of the nanocomposites. The results were applied to an alumina-filled adhesive in a single lap shear configuration demonstrating the capability of the technique to monitor R-line peak positions with high spatial resolution and …

Performance Of Control Room Operators In Alarm Management, Dileep Buddaraju

LSU Master's Theses

Pipelines transport millions of barrels of petroleum products every day. These systems have significant safety concerns. The BP oil spill in the Gulf of Mexico, while concerned with oil and gas extraction rather than distribution, shares many of the same safety and reliability issues as distribution systems, and demonstrates the significant potential for major disasters in the pipeline industry. In this work, a research study is being conducted to further understanding of the role of operators in the management of alarm systems and to measure the performance of operators in handling abnormal situations like pressure loss, liquid inflow/outflow variation and …

The Transient Wave Effect And Real Losses Correlation-Frequency, Temporal, And Spatial Analysis, Dina Sa Knight

LSU Master's Theses

Water distribution systems are prone to transients since pumps need to be started and stopped, pumps may have sudden flow changes, human blunders can occur, equipment may fail, or other unavoidable natural events may ensue. Surge modeling techniques are available to calculate variations in pressure, under extreme or normal operating conditions, serving as a tool to predict extreme events in order to design a suitable system and, or, to aid in the implementation of proper measures to mitigate transients. However, modeling an entire water network system may not be cost effective and may require extensive research and time especially in …

An Euler Solver For Nonlinear Water Waves Using A Modified Staggered Grid And Gaussian Quadrature Approach, Qi Fan

LSU Master's Theses

A structured, finite-volume Euler solver for non-hydrostatic, free surface flows is developed to simulate coastal nonlinear dispersive water waves. A semi-implicit projection method which splits the pressure term into hydrostatic and non-hydrostatic parts is employed. A vertically shifted, staggered grid is designed to accommodate a new Gaussian discharge calculator and to facilitate the enforcement of a non-hydrostatic free-surface boundary condition. The Gaussian discharge calculator on the shifted grid increases the dispersion accuracy compared to traditional approaches that calculate discharges on a regular staggered grid. Numerical results are presented to demonstrate the improvements of these methods.

Solving Evolution Equations For Triad Interaction Of Shallow Water Waves, Qian Zhang

LSU Master's Theses

This study focuses on solving the evolution equations for triad interaction in shallow water waves. First, the evolution equations based on Boussinesq-type equations with Pad¨¦ approximant of the exact linear phase velocity using multi-scale perturbation analysis are derived. Next, methods of solving the complex equation directly, splitting the complex function into amplitude and phase functions, and splitting complex function into real and imaginary parts are implemented to solve the evolution equations. Then the fourth-order Runge-Kutta (RK4) numerical scheme is employed to solve the evolution equations, and corresponding numerical results of three wave interaction are presented demonstrating the sensitivity of the …

Effects Of Silicon Content And Cooling Rate On Mechanical Properties Of Heavy Section Ductile Cast Iron , Meghan Haycock

Dissertations, Master's Theses and Master's Reports - Open

The effects of Si and cooling rate are investigated for their effect on the mechanical properties and microstructure. Three alloys were chosen with varying C and Si contents and an attempt to keep the remainder of the elements present constant. Within each heat, three test blocks were poured. Two blocks had chills – one with a fluid flowing through it to cool it (active chill) and one without the fluid (passive) – and the third block did not have a chill. Cooling curves were gathered and analyzed. The mechanical properties of the castings were correlated to the microstructure, cooling rate …

Processing And Mechanical Properties Of Cast Aluminum Containing Scandium, Zirconium, And Ytterbium , Nicholas D. Johnson

Dissertations, Master's Theses and Master's Reports - Open

A series of aluminum alloys containing additions of scandium, zirconium, and ytterbium were cast to evaluate the effect of partial ytterbium substitution for scandium on tensile behavior. Due to the high price of scandium, a crucible-melt interaction study was performed to ensure no scandium was lost in graphite, alumina, magnesia, or zirconia crucibles after holding a liquid Al-Sc master alloy for 8 hours at 900 °C in an argon atmosphere. The alloys were subjected to an isochronal aging treatment and tested for conductivity and Vickers microhardness after each increment. For scandium-containing alloys, peak hardnesses of 520-790 MPa, and peak tensile …

High Temperature, Low Cycle Fatigue Of A Hybrid Particulate/Fiber Aluminum Metal-Matrix Composite , Justin Clark

Dissertations, Master's Theses and Master's Reports - Open

The effect of shot particles on the high temperature, low cycle fatigue of a hybrid fiber/particulate metal-matrix composite (MMC) was studied. Two hybrid composites with the general composition A356/35%SiC particle/5%Fiber (one without shot) were tested. It was found that shot particles acting as stress concentrators had little effect on the fatigue performance. It appears that fibers with a high silica content were more likely to debond from the matrix. Final failure of the composite was found to occur preferentially in the matrix. SiC particles fracture progressively during fatigue testing, leading to higher stress in the matrix, and final failure by …