Mechanical Engineering Commons^™

Acoustic Nonlinearity Parameters For Transversely Isotropic Polycrystalline Materials, Christopher M. Kube, Joseph A. Turner

Department of Mechanical and Materials Engineering: Faculty Publications

This article considers polycrystalline materials with macroscopic elastic anisotropy and the effect of the anisotropy on the quadratic nonlinearity parameter used to describe second harmonic generation in solids. The polycrystal is assumed to have transversely isotropic elastic symmetry, which leads to a directional dependence of the nonlinearity parameters. Additionally, the anisotropy leads to second harmonic generation from an input shear wave. Estimates of the longitudinal and shear wave nonlinearity parameters are given as a function of single-crystal elastic constants, macroscopic anisotropy constants, and propagation direction. An inverse model is presented that relates measured nonlinearity parameters to the macroscopic anisotropy constants. …

Interfacial Electronic Structure At The Ch3nh3pbi3/Moox Interface, Peng Liu, Xiaoliang Liu, Lu Lyu, Haipeng Xie, Hong Zhang, Dongmei Niu, Han Huang, Cheng Bi, Zhengguo Xiao, Jinsong Huang, Yongli Gao

Department of Mechanical and Materials Engineering: Faculty Publications

Interfacial electronic properties of the CH₃NH₃PbI₃ (MAPbI₃)/M_oOx interface are investigated using ultraviolet photoemission spectroscopy and X-ray photoemission spectroscopy. It is found that the pristine MAPbI₃ film coated onto the substrate of poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate)/indium tin oxide by two-step method behaves as an n-type semiconductor, with a band gap of ~1.7 eV and a valence band edge of 1.40 eV below the Fermi energy (EF). With the MoOx deposition of 64A ° upon MAPbI3, the energy levels of MAPbI3 shift toward higher binding energy by 0.25 eV due to electron transfer …

The Operation Mechanism Of Poly(9,9-Dioctylfluorenyl-2,7-Diyl) Dots In High Efficiency Polymer Solar Cells, Chunyu Liu, Yeyuan He, Xinyuan Zhang, Zhiqi Li, Liang Shen, Zhihui Zhang, Wenbin Guo, Shengping Ruan

Department of Mechanical and Materials Engineering: Faculty Publications

The highly efficient polymer solar cells were realized by doping poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) dots into active layer. The dependence of doping amount on devices performance was investigated and a high efficiency of 7.15% was obtained at an optimal concentration, accounting for a 22.4% enhancement. The incorporation of PFO dots (Pdots) is conducted to the improvement of Jsc and fill factor mainly due to the enhancement of light absorption and charge transport property. Pdots blended in active layer provides an interface for charge transfer and enables the formation of percolation pathways for electron transport. The introduction of Pdots was proven an effective …

Surface Analytical Investigation On Organometal Triiodide Perovskite, Chengong Wang, Xiaoliang Liu, Congcong Wang, Zhengguo Xiao, Cheng Bi, Yuchuan Shao, Jinsong Huang, Yongli Gao

Department of Mechanical and Materials Engineering: Faculty Publications

In a little over a year, there has been an unexpected breakthrough and rapid evolution of highly efficient solid-state hybrid solar cells based on organometal trihalide perovskite materials. This technology has the potential to produce solar cells with the very highest efficiencies while retaining the very lowest cost. The authors have measured the electronic density of states of CH₃NH₃PbI₃ using ultraviolet photoemission spectroscopy (UPS), inverse photoemission spectroscopy (IPES), and x-ray photoemission spectroscopy (XPS). The valence band maximum and conduction band minimum positions are obtained from the UPS and IPES spectra, respectively, by linear extrapolation of …

Evaluation Of Peritoneal Microbubble Oxygenation Therapy In A Rabbit Model Of Hypoxemia, Nathan D. Legband, Jameel A. Feshitan, Mark A. Borden, Benjamin S. Terry

Department of Mechanical and Materials Engineering: Faculty Publications

Alternative extrapulmonary oxygenation technologies are needed to treat patients suffering from severe hypoxemia refractory to mechanical ventilation. We previously demonstrated that peritoneal microbubble oxygenation (PMO), in which phospholipid-coated oxygen microbubbles (OMBs) are delivered into the peritoneal cavity, can successfully oxygenate rats suffering from a right pneumothorax. This study addressed the need to scale up the procedure to a larger animal with a splanchnic cardiac output similar to humans. Our results show that PMO therapy can double the survival time of rabbits experiencing complete tracheal occlusion from6.6 ± 0.6 min for the saline controls to 12.2 ± 3.0 min for the …

Efficiency Enhancement In Polymer Solar Cells With A Polar Small Molecule Both At Interface And In The Bulk Heterojunction Layer, Zhengguo Xiao, Qingfeng Dong, Qi Wang, Wenjing Tian, Hui Huang, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

The polar molecules, including ferroelectric materials with large dipole moments, have been applied as interfacial layers to increase the efficiency of organic solar cells by increasing the bounded charge separation, tuning the energy levels, etc. Here, we report a small polar molecule 2-cyano-3- (4-(diphenylamino) phenyl)acrylic acid (TPACA) that can be either blended in the active layer or at the polymer/electrode interface to increase the efficiency of organic solar cell devices after poling. It is found that the built-in potential of the device is increased by 0.2 V after poling under negative bias. Blending TPACA into the active layer has shown …

Towards Tuning The Mechanical Properties Of Three-Dimensional Collagen Scaffolds Using A Coupled Fiber-Matrix Model, Shengmao Lin, Lauren A. Hapach, Cynthia Reinhart-King, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Scaffold mechanical properties are essential in regulating the microenvironment of three-dimensional cell culture. A coupled fiber-matrix numerical model was developed in this work for predicting the mechanical response of collagen scaffolds subjected to various levels of non-enzymatic glycation and collagen concentrations. The scaffold was simulated by a Voronoi network embedded in a matrix. The computational model was validated using published experimental data. Results indicate that both non-enzymatic glycation-induced matrix stiffening and fiber network density, as regulated by collagen concentration, influence scaffold behavior. The heterogeneous stress patterns of the scaffold were induced by the interfacial mechanics between the collagen fiber network …

Electrospray Of An Energetic Ionic Liquid Monopropellant For Multi-Mode Micropropulsion Applications, Steven P. Berg, Joshua L. Rovey, Benjamin D. Prince, Shawn W. Miller, Raymond J. Bemish

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The multi-mode chemical-electric propulsion capable energetic ionic liquid propellant [Emim][EtSO4]-HAN is electro sprayed in a 100 µm capillary emitter to test the electric-mode performance of the propellant. The ionic liquid exhibits stable electrospray emission in both cation and anion extraction modes at a nominal extraction voltage of 3400 V. Near field measurements of current and mass flow rate distribution are taken at flow rates from 0.19 nL/s to 3.06 nL/s. Total emission current, as measured by Faraday cup and integrated, increases from 754 nA to 3195 nA for cation emission and from 552 nA to 2012 nA for anion emission. …

Stochastic Interdigitation As A Toughening Mechanism At The Interface Between Tendon And Bone, Y. Hu, Victor Birman, A. Demyier-Black, A. G. Schwartz, S. Thomopoulos, G. M. Genin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

A Novel In Situ Microscope For Studying Benthic Organisms, Andrew Mullen

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Coastal marine ecosystems such as coral reefs, kelp forests, sea grass beds and mangroves have significant societal value. As economic resources they support tourism, fisheries and storm protection while ecologically they host high biological diversity and productivity. Many basic biological, chemical, and physical processes taking place in these marine ecosystems occur at ‘micro-­‐scales’ less than a millimeter in size. Examples of significant micro-­‐scale activities include: coral bleaching of their single-­‐ celled symbiotic algae, larval settlement and attachment, competition between sessile organisms along thin interfaces, and fluxes of particles to and from the seafloor. It is also important to consider that …

System Integration Of Hydrogen Energy Technologies Using Renewable Energy Resources, Tarek A Mohammed Hamad

Doctoral Dissertations

"The objective of this work has two major tasks that investigation the use of CHHP system at the Missouri University of Science and Technology (Missouri S&T) campus and studying solid waste as renewable source of energy: current and future possibility in Libya. Task one has three major topics. In Topic I, Design of Combined Hydrogen, Heat and Power (CHHP) system for the campus using local resources and treated biogas can be used to generate CHHP using a Molten Carbonate Fuel Cell (MCFC). In Topic II, hydrogen recovery and cleaning system, Heat recovery and electric power usage, hydrogen compression, storage, and …

High-Resolution Bottom-Loss Estimation Using The Ambient-Noise Vertical Coherence Function, Lanfranco Muzi, Martin Siderius, Jorge E. Quijano, Stan E. Dosso

Electrical and Computer Engineering Faculty Publications and Presentations

The seabed reflection loss (shortly "bottom loss") is an important quantity for predicting transmission loss in the ocean. A recent passive technique for estimating the bottom loss as a function of frequency and grazing angle exploits marine ambient noise (originating at the surface from breaking waves, wind, and rain) as an acoustic source. Conventional beamforming of the noise field at a vertical line array of hydrophones is a fundamental step in this technique, and the beamformer resolution in grazing angle affects the quality of the estimated bottom loss. Implementation of this technique with short arrays can be hindered by their …

Local Alternative Sources For Cogeneration Combined Heat And Power System, Abdulhakim Amer Agll

Doctoral Dissertations

"Global demand for energy continues to grow while countries around the globe race to reduce their reliance on fossil fuels and greenhouse gas emissions by implementing policy measures and advancing technology. Sustainability has become an important issue in transportation and infrastructure development projects. While several agencies are trying to incorporate a range of sustainability measures in their goals and missions, only a few planning agencies have been able to implement these policies and they are far from perfect. The low rate of success in implementing sustainable policies is primarily due to incomplete understanding of the system and the interaction between …

Rigidly Foldable Origami Twists, Thomas A. Evans, Robert J. Lang, Spencer P. Magleby, Larry L. Howell

Faculty Publications

Rigid foldability is an important characteristic of origami structures that becomes significant with non-paper materials. A rigidly foldable origami tessellation is one where the sectors remain rigid and all deflection occurs at the crease lines. Many rigidly foldable patterns have only one degree of freedom, making them potentially useful for deployable structures. Methods have been developed to construct rigidly foldable origami tessellations using materials with finite thickness based on zero-thickness rigidly foldable patterns. [Tachi 11].

Origami methods have been considered for application in deployable structures such as solar panels [Miura 85] [Zirbel et al. 13] and sterile shrouds [Francis et …

Phase Transitions And In Situ Dynamics Of Crystal Grain Formation Of Alumina Nanotubes Templated By Vertically Aligned Carbon Nanotubes, L. F. Lampert, A. Barnum, S. W. Smith, J. F. Conley, Jun Jiao

Mechanical and Materials Engineering Faculty Publications and Presentations

Phase transitions of amorphous alumina (a-alumina) nanotubes grown by atomic layer deposition and templated by carbon nanotubes were investigated with thermal annealing, transmitted Kikuchi electron diffraction, electron-irradiation-induced crystallization, X-ray diffraction, and X-ray photoelectron spectroscopy. The resulting, engineered alumina nanotube arrays demonstrate a large range of tunable phases that are vital for understanding how alumina nanotube arrays can be applied for uses within biotechnology, catalysis, and other academic and industrial uses.

Anisotropy Of The Reynolds Stress Tensor In The Wakes Of Wind Turbine Arrays In Cartesian Arrangements With Counter-Rotating Rotors, Nicholas Hamilton, Raúl Bayoán Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

A 4 × 3 wind turbine array in a Cartesian arrangement was constructed in a wind tunnel setting with four configurations based on the rotational sense of the rotor blades. The fourth row of devices is considered to be in the fully developed turbine canopy for a Cartesian arrangement. Measurements of the flow field were made with stereo particle-image velocimetry immediately upstream and downstream of the selected model turbines. Rotational sense of the turbine blades is evident in the mean spanwise velocity W and the Reynolds shear stress −vw. The flux of kinetic energy is shown to be of greater …

Thermodynamic Grain Size Stabilization Models: An Overview, Mostafa Saber, Carl C. Koch, Ronald O. Scattergood

Mechanical and Materials Engineering Faculty Publications and Presentations

Grain boundaries in a nanocrystalline microstructure produce an increase in the excess free energy of the system. Grain growth is a consequence of the thermodynamic driving force reducing this excess. Thermodynamic stabilization is an approach based on eliminating the driving force by suitable alloy additions that can produce a metastable equilibrium state at the nanoscale grain size, as opposed to kinetic stabilization where the grain growth mobility is restricted by pinning and/or drag mechanisms. The present paper reviews and compares various models proposed for thermodynamic stabilization.

Estimation Of Transient Temperature Distribution During Quenching, Via A Parabolic Model, Diego E. Lozano, Gabriela Martinez-Solis, Rafael David Mercado-Solis, Rafael Colás, George E. Totten

Mechanical and Materials Engineering Faculty Publications and Presentations

A material-independent model to estimate the transient temperature distribution in a test probe quenched by immersion is presented in this study. This model is based on the assumption that, under one-dimensional unsteady heat conduction, the radial temperature distribution at the end of an interval belongs to the equation of a parabola. The model was validated using AISI 304 stainless steel test probes (Φ8×40 mm and Φ12×60 mm) quenched from 850 to 900 °C in water and in water-based NaNO2 solutions at 25 °C and in canola oil at 50 °C. Additionally, square test probes (20×20×100 mm) were quenched from 550 …

Relationship Between Product Quality And Customer Satisfaction, Albert Vitales Cruz

Walden Dissertations and Doctoral Studies

The National Safety Council (NSC) estimated that over 35,000 people died in U.S. traffic accidents. About 3.8 million traffic crash injuries requiring medical attention occurred in 2013, and the number of deaths was about the same over the last 5 years. The NSC found that product recalls, car repairs, injuries, and deaths were due to unsafe product designs or inferior product quality. These statistics underscore the challenge of producing quality vehicles while satisfying customers. The purpose of this nonexperimental study was to examine relationships among product (vehicle) quality, product cost, product safety, and consumer satisfaction. The hypotheses inquired the extent …

Design Studies Of Infrastructural Development For Applications Of Hydrogen Energy Technologies, Yousif M. H. Hamad

Doctoral Dissertations

"Countries around the world are trying to reduce their energy consumption, fossil fuel usage, and greenhouse gas (GHG) emissions. According to the International Energy Outlook 2012 released by the U.S. Energy Information Administration (EIA), the estimated fuel economy and greenhouse gas emissions standards proposed for light-duty vehicles for model years 2017-2025 has an increase of 44% in fuel economy and a reduction of 34% in GHG emissions. The use of alternative fuel vehicles and renewable energy sources are, therefore, inevitable toward achieving this goal. Biogas has untapped potential as an alternative energy source. This immediately available resource would allow countries …

Spatial And Temporal Modulation Of Heat Source Using Light Modulator For Advanced Thermography, Arvindvivek Ravichandran

Masters Theses

"Thermography is a Non-Destructive Testing (NDT) method that has found increasing use in industry and research. It has the advantages of being non-contact and be able to interrogate a large surface simultaneously. Active thermography using flash lamps as heat source has been demonstrated for identifying blind holes and delamination in composites. Despite these advancements, active thermographic approach fails to defects like cracks. Under uniform illumination heat flow is predominantly 1D and can easily circumvent a narrow feature. This can be overcome by using a focused light/laser source onto the surface to impose a 3D heat flux. The disadvantage is that …

Spectral Radiation Analysis Of Premixed Oxy-Syngas And Oxy-Methane Flames, Naznin Jahan Afrose

Open Access Theses & Dissertations

Oxy-fuel combustion has potential to be an impeccable enhancement of current combustion techniques. For a hydrocarbon burning with oxygen the resulting exhaust stream is composed mainly of carbon dioxide and water vapor. This exhaust allows for easier carbon capture and sequestration since the water can be condensed out. Another advantage is the significant reduction of NOx since much of the nitrogen found in air-combustion systems is eliminated. These processes also provide a higher theoretical efficiency which is advantageous. Although beneficial many of the exhaust gas products radiative characteristics are unknown. Motivated by this, this paper focuses on the spectral radiation …

Multi-3d System: Advanced Manufacturing Through The Implementation Of Material Handling Robotics, Jose Luis Coronel Jr.

Open Access Theses & Dissertations

Since the rise of additive manufacturing (AM), innovation has been at the forefront. Additive Manufacturing systems that incorporate complex processes are steadily being developed. One example is the Multi3D System, which was designed to integrate the ability to print multi-material parts with that of embedding electronics. To achieve this automated process, the Multi3D incorporates a six-axis robotic arm to transfer a build platform containing a printed part, to various manufacturing stations (two fused deposition modeling (Stratasys, FDM400mc) systems and a computer numerical control router (Techno CNC Router). The robot is a Yaskawa Motoman MH50 chosen for its payload capacity of …

Addressing New Skills Needed For The Automotive Industry Through A Motorsports Educational Pathway, Vukica M. Jovanovic, Mileta M. Tomovic, Alok K. Verma, Nathan Luetke, Steve Branch

Engineering Technology Faculty Publications

The automotive industry has higher-skilled positions available that need engineers and engineering technologists qualified and capable to work in a high-paced, advanced manufacturing sector. Various educational programs across the country offer programs related to the motorsports area at the Associate of Science level. There are also various articu-lation agreements that enable students to continue their education to the baccalaureate level. These programs try to fill in the gap related to the skills shortage in systems and new design methods and processes. The main strength of such educational pathways is that students, who are trained to work as technicians with an …

Offshore Turbine Arrays: Numerical Modeling And Experimental Validation, Thomas Kroll, William Hall, Ian Gagnon

Honors Theses and Capstones

The interaction between wind turbines in a large wind farm needs to be better understood to reduce array losses and improve energy production. A numerical test bed for an array of offshore wind turbines was developed in the open-source computational fluid dynamics (CFD) framework OpenFOAM. It provides a computational tool which can be used in combination with physical model turbine array studies in the Flow Physics Facility (FPF) at UNH as well as other test facilities.

Turbines were modeled as actuator disks with turbulence sources to reduce computational cost. Both k-ϵ and k-ω SST turbulence models were utilized to capture …

Modeling And Preliminary Characterization Of Passive, Wireless Temperature Sensors For Harsh Environment Applications Based On Periodic Structures, Diego Ivan Delfin Manriquez

Open Access Theses & Dissertations

Wireless temperature sensing has attained significant attention in recent years due to the increasing need to develop reliable and affordable sensing solutions for energy conversion systems and other harsh environment applications. The development of next generation sensors for energy production processing parameters, such as temperature and pressure, can result in better performance of the system. Particularly, continuous temperature monitoring in energy conversion systems can result in enhancements such as better system integrity, less pollution and higher thermal efficiencies. However, the conditions experienced in these system components hinder the performance of current solutions due to the presence of semi-conductor materials and …

An Improved Sin-Hyperbolic Constitutive Model For Creep Deformation And Damage, Mohammad Shafinul Haque

Open Access Theses & Dissertations

Inspection and maintenance of industrial gas turbines (IGTs) cost millions of dollars. Growing demand of obtaining higher IGT efficiency leads to higher temperature and pressure operating conditions. Long exposure of turbine components at elevated temperature and pressure

makes creep damage critically important to consider during planning, designing and operating conditions. Effective and economic maintenance requires accurate creep deformation, damage

evolution and rupture life prediction information. Creep prediction models are used to determine the state of the turbine components and to schedule the inspection, maintenance and replacement time periods. The more accurate the prediction model, the less is the overall cost …

Design Of A High Intensity Turbulent Combustion System, Mohammad Arif Hossain

Open Access Theses & Dissertations

In order to design next generation gas turbine combustor and rocket engines, a systematic study of flame structure at high intensity turbulent flow is necessary. The fundamental study of turbulent premixed combustion has been a major research concern for decades. The work is focused on the design and development of a high intensity turbulent combustion system which can be operated at compressible (0.3 < M < 0.5), preheated (T0=500K) and premixed conditions in order to investigate the 'Thickened Flame' regime. An air-methane mixture has been used as the fuel for this study. An optically accessible backward-facing step stabilized combustor has been designed for a maximum operating pressure of 6 bar. A grid has been introduced with different blockage ratios (BR = 54%, 61% & 67%) in order to generate turbulence inside the combustor for the experiment. Optical access is provided via quartz windows on three sides of the combustion chamber. Finite Element Analysis (FEA) is done in order to verify the structural integrity of the combustor at rated conditions. In order to increase the inlet temperature of the air, a heating section was designed to use commercially available in-line heaters. Separate cooling subsystems have been designed for chamber cooling and exhaust cooling. The LabVIEW software interface has been selected as the control mechanism for the experimental setup. A 10 kHz Time Resolved Particle Image Velocimetry (TR-PIV) system and a 3 kHz Planer Laser Induced Fluorescence (PLIF) system have been integrated with the system in order to diagnose the flow field and the flame respectively. The primary understanding of the flow field inside the combustor was achieved through the use of Detached Eddy Simulation (DES) by using commercially available software package ANSYS FLUENT. Preliminary validation is done by 10 kHz TR-PIV technique. Both qualitative and quantitative analysis have been done for CFD and experiment. Major flow parameters such as average velocity, fluctuation of velocity, kinetic energy, and turbulent intensity have been calculated for two distinct Reynolds number (Re = 815 & 3500). PIV results are compared with CFD results which show significant agreement with each other.

Thermal Shock Studies On Carbon-Carbon Composites: Experimentation And Analysis, Alma Lucia Leanos

Open Access Theses & Dissertations

The oxidation behavior of C/C composites under thermal shock conditions in air is understood and predicted experimentally and by computational efforts. In Chapter. 1, both compressive properties and oxidation behavior of pristine and thermal shock exposed 2D C/C composite specimens were examined. Pristine test specimens were exposed to thermal shock conditions with temperatures ranging from 400°C to 1000°C in an oxidizing environment, followed by compression tests on pristine and thermal shock exposed specimens to obtain their compressive responses.

Similarly, in Chapter. 2, the influence of thermal shock conditions on both, the extent of carbon materials decomposition and the through-thickness compressive …

Fluid Flow Characterization Of High Turbulent Intensity Compressible Flow Using Particle Image Velocimetry, Marco Efrain Quiroz

Open Access Theses & Dissertations

A high turbulent intensity combustion chamber has been designed in order to operate with compressible (0.3 < M < 0.5) and preheated (T=500K) air-methane combustion. These conditions will allow the investigation of different flame regimes; most notably the proposed "Thickened Flame" regime. Initial design and flow validation has been completed in order to begin further experimentation. A 10 kHz Time Resolved Particle Image Velocimetry (TR-PIV) system and a 3 kHz Planer Laser Induced Fluorescence (PLIF) system have been integrated with the system in order to diagnose the flow field and the flame respectively. The exhaust and chamber cooling subsystems were designed to comply with safety regulations, and the control systems were set up in a way that allows automated (LabVIEW) and user controlled sequencing. This work's main purpose is to characterize and map the flow properties at maximum flow conditions (M > 0.3) in order to map the following; flow structures, kinetic energy at different length scales, velocity fluctuations and turbulent intensity. PIV measurements are carried out for three different volumetric flow rates (ð???Ì? = 25 scfm, 55 scfm, and 115 scfm) and three different grid geometries for each (BR= 67%, 61%, and 54%). Upon finding that the main flow structure consisted of jets caused by the grid at higher flowrates, experiments were done with a grid BR = 67% which was thinner (50% of original …