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Articles 1 - 22 of 22
Full-Text Articles in Mechanical Engineering
Loss Enhanced Transmission And Collimation In Anisotropic Epsilon-Near-Zero Metamaterials, L. Sun, S. Feng, Xiaodong Yang
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
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 …
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
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 …
Modeling, Analysis And Simulation Of Paste Freezing In Freeze-Form Extrusion Fabrication, Mingyang Li, Robert G. Landers, Ming-Chuan Leu
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
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 …
Experimental Study Of Polymer Electrolyte Membrane Fuel Cells Using A Graphite Composite Bipolar Plate Fabricated By Selective Laser Sintering, Nannan Guo, Ming-Chuan Leu
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 …
The Applications Of Additive Manufacturing Technologies In Cyber-Enabled Manufacturing Systems, Sriram Praneeth Isanaka, Frank W. Liou
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
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.
Reduction Of Solid-Solid Thermal Boundary Resistance By Inserting An Interlayer, Zhi Liang, Hai-Lung Tsai
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
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
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
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
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
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
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 …
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
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
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 …
Electronic Musical Instrument, M. Nakagawa, Shun Takai
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
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 …
Generating Tones With A Vibrato Effect, M. Nakagawa, Shun Takai
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 …
Effects Of Riblets On Skin Friction And Heat Transfer In High-Speed Turbulent Boundary Layers, Lian Duan, Meelan M. Choudhari
Effects Of Riblets On Skin Friction And Heat Transfer In High-Speed Turbulent Boundary Layers, Lian Duan, Meelan M. Choudhari
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Direct numerical simulations of spatially developing turbulent boundary layers over riblets are conducted to examine the effects of riblets on skin friction and heat transfer at high speeds. Zero-pressure gradient boundary layers under two flow conditions (Mach 2.5 with Tw/Tr = 1 and Mach 7.2 with Tw/Tr = 0.5) are considered. Simulations are conducted for boundary-layer flows over a clean surface and symmetric V-groove riblets. The DNS results at Mach 2.5 confirm the few existing experimental observations and show that a drag reduction of approximately 7% can be achieved for riblets with proper spacing. The comparisons in turbulence statistics and …
Design Of Metallic Bipolar Plates For Pem Fuel Cells, Sriram Praneeth Isanaka, Austin Das, Frank W. Liou
Design Of Metallic Bipolar Plates For Pem Fuel Cells, Sriram Praneeth Isanaka, Austin Das, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This project focused on the design and production of metallic bipolar plates for use in PEM fuel cells. Different metals were explored and stainless steel was found out to be best suited to our purpose. Following the selection of metal, it was calculated that to produce 0.7 W of power, the bipolar plate should have an active surface of 25cm2. The bipolar plates were designed with different flow field patterns and manufactured. Different flow field patterns that were used were the straight design, serpentine, multiple serpentine, pintype, interdigitated design and other custom designs. These plates were then assembled along with …