Mechanical Engineering Commons^™

Loss Enhanced Transmission And Collimation In Anisotropic Epsilon-Near-Zero Metamaterials, L. Sun, S. Feng, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We verify the extraordinary transmission enhancement and collimation induced by the material loss in anisotropic epsilon-near-zero metamaterials, and reveal the physical mechanism of this exotic electromagnetic phenomenon via the iso-frequency contour analysis. In addition, we demonstrate the possibility in realization of such loss enhanced transmission of Gaussian beam in realistic silver-germanium multilayered structures by applying full-wave numerical simulations.

A Method To Generate Pressure Gradients For Molecular Simulation Of Pressure-Driven Flows In Nanochannels, Zhi Liang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

One of the Difficulties in Molecular Simulation of Pressure-Driven Fluid Flow in Nanochannels is to Find an Appropriate Pressure Control Method. When Periodic Boundary Conditions (PBCs) Are Applied, a Gravity-Like Field Has Been Widely Used to Replace Actual Pressure Gradients. the Gravity-Fed Method is Not Only Artificial, But Not Adequate for Studying Properties of Fluid Systems Which Are Essentially Inhomogeneous in the Flow Direction. in This Paper, a Method is Proposed Which Can Generate Any Desired Pressure Difference to Drive the Fluid Flow by Attaching a "Pump" to the Nanofluidic System, While the Model is Still Compatible with PBCs. the …

Modeling, Analysis And Simulation Of Paste Freezing In Freeze-Form Extrusion Fabrication, Mingyang Li, Robert G. Landers, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During the freeze-form extrusion fabrication process for aqueous-based pastes, the sub-zero temperature environment aids the part in maintaining its shape by freezing the water present in the paste. The paste freezes very quickly when deposited on a substrate in a freezing environment. However, as the part’s height increases, the freezing time increases as the heat conduction rate to the substrate decreases. The freezing time can exceed the time required to extrude one layer of paste due to water’s high latent heat, thus leaving the extruded paste in its semi-liquid state and causing the part to deform or even collapse. Therefore, …

Comparison Of Compression Molding And Selective Laser Sintering Processes In The Development Of Composite Bipolar Plates For Proton Exchange Membrane Fuel Cells, Ehsan Taghipour, Ming-Chuan Leu, Nannan Guo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Bipolar plates are key components of Proton Exchange Membrane (PEM) fuel cells. They carry current away from the cell and withstand the clamping force of the stack assembly. Therefore, PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical strength, in addition to being light weight and low cost in terms of both applicable materials and production methods. In order to attain these goals, we have manufactured graphite-carbon- polymer composite plates using Compression Molding (CM), which is suitable for mass production, and Selective Laser Sintering (SLS), which is suitable for making prototypes. In this paper, the electrical …

The Applications Of Additive Manufacturing Technologies In Cyber-Enabled Manufacturing Systems, Sriram Praneeth Isanaka, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The application of networked sensors and control in various areas, such as smart grids and infrastructures, has become a recent trend, called cyber-physical systems. The Cyber Enabled Manufacturing (CEM) environment is to apply these technologies in manufacturing systems to handle a significantly greater magnitude of manufacturing data. Additive manufacturing techniques print or place material layer by layer to form a part, thus have a great potential to help accelerate CEM process by printing or embedding sensors and actuators in the proper locations. This paper summarizes the roles of additive manufacturing technologies to help establish a CEM environment.

Interactions Of An Additive Manufacturing Program With Society, Frank W. Liou, Ming-Chuan Leu, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive Manufacturing (AM) has shown considerable promise for the future but also proposes some challenges. Many AM barriers tend to be non-technical and instead are human-centric issues such as lack of education of practitioners in AM capabilities, cultural differences, vested interests, and potentially lack of imagination. It is highly desirable for all research and educational institutions to help address these issues. This paper summarizes the additive manufacturing research and education program at the Missouri University of Science and Technology (Missouri S&T) and its interactions with various constituents, including K-12 students, undergraduate and graduate students, distance students, and industry.

Freeze-Form Extrusion Fabrication Of Functionally Graded Material Composites Using Zirconium Carbide And Tungsten, Ang Li, Aaron S. Thornton, Bradley K. Deuser, Jeremy Lee Watts, Ming-Chuan Leu, Greg Hilmas, Robert G. Landers

Materials Science and Engineering Faculty Research & Creative Works

Ultra-high-temperature ceramics are being investigated for future use in aerospace applications due to their superior thermo-mechanical properties, as well as their oxidation resistance, at temperatures above 2000⁰C. However, their brittleness makes them susceptible to thermal shock failure. As graded composites, components fabricated as functionally-graded materials (FGMs) can combine the superior properties of ceramics with the toughness of an underlying refractory metal. This paper discusses the grading of two materials through the use of a Freeze-form Extrusion Fabrication (FEF) system to build FGM parts consisting of zirconium carbide (ZrC) and tungsten (W). Aqueous-based colloidal suspensions of ZrC and W were developed …

Experimental Study Of Polymer Electrolyte Membrane Fuel Cells Using A Graphite Composite Bipolar Plate Fabricated By Selective Laser Sintering, Nannan Guo, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Selective Laser Sintering (SLS) can be used to fabricate graphite composite bipolar plates with complex flow fields for Polymer Electrolyte Membrane (PEM) fuel cells. The additive manufacturing process can significantly reduce the time and cost associated with the research and development of bipolar plates as compared to other fabrication methods such as compression molding. In this study, bipolar plates with three different designs, i.e., parallel in series, interdigitated, and bio-inspired, were fabricated using the SLS process. The performance of these SLS-fabricated bipolar plates was studied experimentally within a fuel cell assembly under various operating conditions. The effect of temperature, relative …

Reduction Of Solid-Solid Thermal Boundary Resistance By Inserting An Interlayer, Zhi Liang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An Effective Method is Proposed to Greatly Improve the Thermal Transport Across the Interface between Two Solids with Dissimilar Phonon Spectra. If the Two Solids Have Similar Crystal Structure and Lattice Constant, It is Predicted from the Molecular Dynamics Modeling that an over 50% Reduction of the Thermal Boundary Resistance Can Be Achieved by Inserting a 3-Unit-Cell-Thick Interlayer Whose Debye Temperature is Approximately the Square Root of the Product of the Debye Temperatures of the Two Solids. on the Other Hand, If the Two Solids Have a Large Difference in Lattice Constant, It is Found the Interfacial Atomic Restructuring Plays …

Phase Resolved Near-Field Mode Imaging For The Design Of Frequency-Selective Surfaces, Edward C. Kinzel, J. C. Ginn, R. L. Olmon, D. J. Shelton, B. A. Lail, I. Brenner, M. B. Sinclair, M. B. Raschke, G. D. Boreman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

A Nanoporous Silicon Nitride Membrane Using A Two-Step Lift-Off Pattern Transfer With Thermal Nanoimprint Lithography, Bhargav P. Nabar, Zeynep Çelik-Butler, Brian H. Dennis, Richard E. Billo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nanoimprint lithography is emerging as a viable contender for fabrication of large-scale arrays of 5500 nm features. A fabrication process for the realization of thin nanoporous membranes using thermal nanoimprint lithography is presented. Suspended silicon nitride membranes were fabricated by low-pressure chemical vapor deposition (LPCVD) in conjunction with a potassium hydroxide-based bulk micromachining process. Nanoscale features were imprinted into a commercially available thermoplastic polymer resist using a prefabricated silicon mold. The pattern was reversed and transferred to a thin aluminum oxide layer by means of a novel two-stage lift-off technique. The patterned aluminum oxide was used as an etch mask …

Hybrid Bioreactor For Reduction Of Capital Costs, David J. Bayless

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A bioreactor with first and second containers has translucent sidewalls housing a plurality of planar membranes over which a slurry of water and photosynthetic microorganisms flows. A light collector is mounted adjacent a gap between the first and second containers for receiving incident light and conveying the light through optical waveguides, such as fibers, to distributors. The distributors are mounted in the first and second containers near a lower end of the substrates so that photons incident on the optical waveguides are conveyed through the optical waveguides to the light distributors and then to the lower ends of the substrates …

Advantages Of Gan Based Light-Emitting Diodes With A P-Ingan Hole Reservoir Layer, Taiping Lu, Shuti Li, Chao Liu, Kang Zhang, Yiqin Xu, Jinhui Tong, Lejuan Wu, Hailong Wang, Xiaodong Yang, Yian Yin, Guowei Xiao, Yugang Zhou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A p-type InGaN hole reservoir layer (HRL) was designed and incorporated in GaN based light-emitting diodes (LEDs) to enhance hole injection efficiency and alleviate efficiency droop. The fabricated LEDs with p-type HRL exhibited higher light output power, smaller emission energy shift and broadening as compared to its counterpart. Based on electrical and optical characteristics analysis and numerical simulation, these improvements are mainly attributed to the alleviated band bending in the last couple of quantum well and electron blocking layer, and thus better hole injection efficiency. Meanwhile, the efficiency droop can be effectively mitigated when the p-InGaN HRL was used.

Study Of Turbulence-Radiation Interaction In Hypersonic Turbulent Boundary Layers, L. (Lian) Duan, M. P. Martín, A. M. Feldick, M. F. Modest, D. A. Levin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations are conducted to investigate the effect of turbulence-radiation interaction in hypersonic turbulent boundary layers, representative of the Orion crew exploration vehicle at the peak heating condition during reentry. Both the effects of emission and absorption are considered by solving the radiative transfer equation using the tangent slab approximation and a spectral model with line-by-line accuracy. Nondimensional governing parameters to measure the significance of turbulence-radiation interaction are proposed, and the direct numerical simulation fields with and without radiation coupling are used to assess turbulence-radiation interaction. Is it found that the fluid medium within the boundary layer is optically …

Electronic Musical Instrument To Generate Musical Tones To Imitate A Stringed Instrument, M. Nakagawa, Shun Takai, Shun Takai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Provided are an electronic musical instrument, computer Storage device, and method for generating tone. A sound source in an electronic musical instrument generates a first tone at a first pitch in response to a first tone generation instruction received by an input device of the electronic musical instrument. A second tone generation instruction is received to generate a second tone at a second pitch while generating the first tone at the sound source. A determination is made of a pitch difference of the first and the second pitches. The sound source is controlled to generate the second tone and to …

Electronic Musical Instrument, M. Nakagawa, Shun Takai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Provided are an electronic musical instrument, computer storage device, and method generating tones for held notes. Indication is made of held notes having pitches as held in response to receiving note-on information for the held notes from an input device of an electronic musical instrument while receiving hold information from a hold device of the electronic musical instrument. Note-on information is received for a received note having a pitch while generating the pitches for the held notes. Selection is made of one of the held notes to release according to a first selection criteria in response to determining that the …

Adjusting A Level At Which To Generate A New Tone With A Current Generated Tone, M. Nakagawa, Shun Takai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Provided are a tone control device and a method for adjusting a volume level at which to generate a new tone and at least one current tone according to a target volume level and a current volume level. A note-on event associated with a received volume level is received from an input device. A current volume level is processed to determine a new volume level in response to receiving the note-on event while generating at least one current tone at the current volume level. The at least one current tone and a new tone associated with the received note-on event …

Biological Evaluation Of A Novel Tissue Engineering Scaffold Of Layered Double Hydroxides (Ldhs), Fateme Fayyazbakhsh, Mehran Solati-Hashjin, M. A. Shokrgozar, S. Bonakdar, Y. Ganji, N. Mirjordavi, S. A. Ghavimi, P. Khashayar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Bone Tissue Engineering (BTE) Composed of Three Main Parts: Scaffold, Cells and Signaling Factors. Several Materials and Composites Are Suggested as a Scaffold for BTE. Biocompatibility is One of the Most Important Property of a BTE Scaffold. in This Work Synthesis of a Novel Nanocomposite Including Layered Double Hydroxides (LDH) and Gelatin is Carried Out and its Biological Properties Were Studied. the Co-Precipitation (PH=11) Method Was Used to Prepare the LDH Powder, using Calcium Nitrate, Magesium Nitrate and Aluminum Nitrate Salts as Starting Materials. the Resulted Precipitates Were Dried. X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron …

Numerical Study Of Pressure Fluctuations Due To High-Speed Turbulent Boundary Layers, Lian Duan, Meelan M. Choudhari, Minwei Wu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by fully developed turbulence in supersonic turbulent boundary layers with an emphasis on both pressure fluctuations at the wall and the acoustic fluctuations radiated into the freestream. The wall and freestream pressure fields are first analyzed for a zero-pressure gradient boundary layer with Mach 2.5 and Reynolds number based on momentum thickness of approximately 2835. The single and multi-point statistics reported include the wall pressure fluctuation intensities, frequency spectra, space-time correlations, and convection velocities. Single and multi-point statistics of surface pressure fluctuations show good agreement with measured data …

Microlens Array Light Trapping In Cdte/Cds Solar Cells, Patrick Michael Margavio

Masters Theses

"In light of the continued rise in fossil fuel costs, alternative energy sources, such as solar technology, are increasingly important. Concentrating photovoltaic systems are promising for future efficient and cost effective competition with fossil fuels. A microlens array is employed to a CdTe/CdS semiconducting solar cell to increase efficiency via light trapping. Since the microlens array will cause a local increase in incident light intensity, it should cause a corresponding increase in efficiency. The solar cell is deposited layer by layer. The CdS layer is chemically deposited. The CdTe layer is deposited using a novel additive manufacture technique: laser melting …

Manufacturing And Characterization Of Soy-Based Polyurethane Composites, Rama Bhadra Raju Vuppalapati

Doctoral Dissertations

"The major cost drivers for composites are raw materials and manufacturing process. Automated manufacturing processes like pultrusion and low cost bio-based raw materials can significantly lower the cost of composites. Polyurethane (PU) resin systems are being introduced in the pultrusion industry as they have higher performance characteristics and manufacturing feasibility when compared to conventional resin systems such as polyester and vinyl ester. PU resin systems are generally characterized as aromatic and aliphatic. Aliphatic PU has lower mechanical properties than the aromatic resin system due to its chemical structure. Nano materials can be used to increase the mechanical properties of aliphatic …

Development Of A Technique For Testing Of Tensile Properties With Miniature Size Specimens For Metal Additive Manufacturing, Sujitkumar Dongare

Masters Theses

"The study of mechanical properties of metals provides a basis to decide on the capability of a particular metal for a task and also to make predictions about its life. The concepts of stress, strain and strength of materials are employed in practically every engineering discipline. Mechanical properties such as stiffness, yield strength, tensile strength, ductility, toughness, impact resistance, creep resistance, fatigue resistance and others, influence the design, fabrication and service life of equipment. Therefore, more than one property is considered for the material selection process for an application. For complete understanding of any material and its feasibility for a …

A Planning Tool To Predict The Welding Angle In Laser Metal Deposition, Sriram Prabhu

Masters Theses

"Research in Laser Metal Deposition (LMD) has been done rigorously in the past. However, the main challenge that still exists is the production of complex part geometries having overhang features. Production of such features requires individual tracks with a high aspect ratio and wider bead angle. The use of destructible/ non-destructible support structures involves costly post production operations which increase production cost. Tilting or moving the deposition surface can be useful to create overhangs but are applicable only to special cases. Since such techniques have to be used by the manufacturing community, the techniques need to be simple in calculation …

Generic Kinematic Simulation For Verification Of Laser Deposition Tool Paths, Sweta Dhaveji Chakravadhanula

Masters Theses

"The development of 3D visual simulation tool for machine simulation is a key approach in saving time and reducing cost. It is an important step before a manufacturing operation is performed on a part, as a tool to detect collision and validate the operation results. There are several kinds of manufacturing equipment being used and hence there is a need for the development of a generalized method to visually simulate a variety of machines. This paper presents the research conducted on describing machine configuration in a generic format which not only gives useful information, but can also be used as …

Investigating The Effects Of Internally Trapped Residuals On The Performance Of A Homogeneous Charge Compression Ignition (Hcci) Engine, Aaron David Attebery

Masters Theses

"Homogeneous charge compression ignition (HCCI) combustion introduces great opportunity for decreased emissions along with greater engine efficiencies. Implementing an innovative combustion mode such as HCCI presents a great challenge for the engine research community. One such challenge is controlling the innate cyclic variability from this chemical kinetics controlled auto-ignition event when transitioning to or from a SI operating mode. This work includes the study of cycle-to-cycle dynamics that occur within the partial burn regime of an HCCI engine as it approaches the misfire limit. Within this regime there are many successive incomplete combustion events that will impact the next cycle …

5-Axis Tool Path Generation With Collision Detection For Finish Machining Of Freeform Surfaces, Jomy Francis

Masters Theses

"Research in the field of Tool path generation for freeform surfaces has been done intensively in the past. However, the main challenge that still exists is the computational efficiency related to the tool path generation. Tool path generation for freeform surface involves instantaneous calculation of new tool orientations which does not collide with the neighboring surfaces. Since the collision check of tool and neighboring surface is done repetitively at every instant of the tool, the calculations at every instant are to be computationally as easy as possible.

This thesis is composed of one paper. Paper I presents a novel extension …

Generating Tones With A Vibrato Effect, M. Nakagawa, Shun Takai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Provided are a method, computer storage device, and tone control device for generating tones with a vibrato effect. A determination is made of a key depression interval comprising a difference of a current time of a current note from a previous time of a previous note. A performance mode is set to a single tone mode, in which only one note is generated, or a polyphonic mode, in which multiple notes are simultaneously generated, based on the determined key depression interval. The tone is generated to output the current note with a first modulation magnitude in response to determining that …

The Risk Mitigation Strategy Taxonomy And Generated Risk Event Effect Neutralization Method, Daniel A. Krus

Doctoral Dissertations

"In the design of new products and systems, the mitigation of potential failures is very important. The sooner in a product's design mitigation can be performed, the lower the cost and easier to implement those mitigations become. However, currently, most mitigations strategies rely on the expertise of the engineers designing a product, and while models and for failure modes do exist to help, there are no guidelines for performing product changes to reduce risk. To help alleviate this, the risk mitigation strategy taxonomy is created from an empirical collection of mitigation strategies used in industry for failure mitigation, creating a …

Transient Growth And Instability Control Using Iteration-Varying Filter Ilc In Flexible Dual Flywheel System, Tong Mu

Masters Theses

"In the field of precision motion control, many industrial systems have flexible modes. This is especially true for very high performance nanopositioning systems where traditional bearing systems are replaced with flexible structures in order to eliminate sliding friction. The precision motion control is difficult in flexible systems because the rapid phase transition around the resonant frequency must be accurately modeled in order to actively control the resonant motion. In order to experimentally study the effectiveness of various control algorithms on flexible systems, a dual-flywheel flexible system is constructed. The mechatronics system design strategy is presented in this thesis. The control …

Force Sensing Of An Asymmetric Dielectric Barrier Discharge Using Mechanical Resonators, Mark Dawson Emanuel

Masters Theses

"Dielectric barrier discharge (DBD) plasma actuators are of great interest in flow control research and application. DBD plasma actuators are low-cost, lightweight, high voltage devices that have the capability of generating small amounts of thrust on the order of a few tenths of a gram. The thrust is created by rapidly pulsing plasma discharges which correlate to the frequency of the applied alternating current waveform, in the low kilohertz range.

Plasma actuators experience a reactant force generated by the pulsed plasma charging and then expelling air away from the charged surface. This force fluctuates with time as the plasma is …