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Full-Text Articles in Entire DC Network
Ac Conductivity Relaxation Processes In Cacu₃Ti₄O₁₂ Ceramics: Grain Boundary And Domain Boundary Effects, Wei Li, Robert W. Schwartz
Ac Conductivity Relaxation Processes In Cacu₃Ti₄O₁₂ Ceramics: Grain Boundary And Domain Boundary Effects, Wei Li, Robert W. Schwartz
Materials Science and Engineering Faculty Research & Creative Works
The ac conductivity of CaCu₃Ti₄O₁₂ ceramics associated with electrical charge carrier motion (ions or vacancies) was investigated as a function of frequency at different temperatures. The long range migration of charge carriers within the ceramic is restricted by two kinds of insulating barriers, namely, grain boundaries and domain boundaries. The potential barriers associated with these boundaries lead to two anomalies in conductivity response and three frequency-dependent contributions to conductivity: long range diffusion of carriers, carrier migration localized within grains, and carrier migration localized within domains.
Microstructural Modification Of As-Cast Al-Si-Mg Alloy By Friction Stir Processing, Z. Y. Ma, S. R. Sharma, Rajiv S. Mishra
Microstructural Modification Of As-Cast Al-Si-Mg Alloy By Friction Stir Processing, Z. Y. Ma, S. R. Sharma, Rajiv S. Mishra
Materials Science and Engineering Faculty Research & Creative Works
Friction stir processing (FSP) has been applied to cast aluminum alloy A356 plates to enhance the mechanical properties through microstructural refinement and homogenization. the effect of tool geometry and FSP parameters on resultant microstructure and mechanical properties was investigated. the FSP broke up and dispersed the coarse acicular Si particles creating a uniform distribution of Si particles in the aluminum matrix with significant microstructural refinement. Further, FSP healed the casting porosity. These microstructural changes led to a significant improvement in both strength and ductility. Higher tool rotation rate was the most effective parameter to refine coarse Si particles, heal the …
Humidification Factors From Laboratory Studies Of Fresh Smoke From Biomass Fuels, D. E. Day, J. L. Hand, C. M. Carrico, Guenter Engling, W. C. Malm
Humidification Factors From Laboratory Studies Of Fresh Smoke From Biomass Fuels, D. E. Day, J. L. Hand, C. M. Carrico, Guenter Engling, W. C. Malm
Materials Science and Engineering Faculty Research & Creative Works
Measurements of smoke aerosol humidification factors were performed in a laboratory for different biomass fuel types and burn conditions. Two nephelometers simultaneously measured dry and humidified light scattering coefficients (bsp(dry) and bsp(RH), respectively), providing the first observations of the temporal evolution of the humidification factor (f(RH) = bsp(RH)/bsp(dry)) for fresh (minutes-old) smoke. Hygroscopic characteristics of the smoke aerosols varied with fuel type and fire conditions, with the mean f(RH) ranging from 1.01 to 1.95 for fresh minutes-old smoke for the relative humidity (RH) range of 70-94%. These f(RH) values exhibited temporal variability, with some fuels alternating from hygroscopic to nonhygroscopic …
Effect Of Friction Stir Processing On The Microstructure Of Cast A356 Aluminum, Z. Y. Ma, S. R. Sharma, Rajiv S. Mishra
Effect Of Friction Stir Processing On The Microstructure Of Cast A356 Aluminum, Z. Y. Ma, S. R. Sharma, Rajiv S. Mishra
Materials Science and Engineering Faculty Research & Creative Works
Friction stir processing (FSP) was applied to cast A356 Al to modify the as-cast microstructure. FSP homogenizes and refines the cast microstructure, completely eliminates porosity, and creates a microstructure with fine Si particles (0.25-0.42 μm) distributed in a fine grain aluminum matrix (3-4 μm). Further, FSP parameters significantly influence microstructural development in the processed zone of cast A356 Al. Generally, higher tool rotation rate creates a more homogeneous microstructure. at lower tool rotation rates, a macroscopically visible banded structure characterized by a low density of coarse particles, was detected in the nugget zone. However, FSP parameters did not significantly influence …
Composite (La, Sr)Mno3-Ysz Cathode For Sofc, Toshio Suzuki, Masanobu Awano, Piotr Jasinski, Vladimir Petrovsky, Harlan U. Anderson
Composite (La, Sr)Mno3-Ysz Cathode For Sofc, Toshio Suzuki, Masanobu Awano, Piotr Jasinski, Vladimir Petrovsky, Harlan U. Anderson
Materials Science and Engineering Faculty Research & Creative Works
(La, Sr) MnO3 (LSM)-Y doped ZrO2 (YSZ) composite was prepared using YSZ colloidal suspension (initial YSZ particle size ∼100 nm), YSZ and LSM polymer precursors on dense substrates at 800 °C annealing temperature. the results of a symmetrical LSM-YSZ composite cell test showed the area specific resistance for overpotential of 0.14 Ω cm2 at 800 °C, which indicated that the LSM-YSZ composite could be a potential candidate for cathode in SOFCs. the performance of the cell with the LSM-YSZ composite cathode and Ni-YSZ anode was investigated and the power density of about 0.26 W cm- 2 was obtained …
Mössbauer And Epr Spectra For Glasses And Glass-Ceramics Prepared From Simulated Compositions Of Lunar And Martian Soils, C. S. Ray, Signo Tadeu Dos Reis, W. M. Pontuschka, J. B. Yang, F. F. Sene, J. M. Giehl, Chang-Soo Kim, S. Sen
Mössbauer And Epr Spectra For Glasses And Glass-Ceramics Prepared From Simulated Compositions Of Lunar And Martian Soils, C. S. Ray, Signo Tadeu Dos Reis, W. M. Pontuschka, J. B. Yang, F. F. Sene, J. M. Giehl, Chang-Soo Kim, S. Sen
Materials Science and Engineering Faculty Research & Creative Works
In situ resource processing and utilization on planetary bodies is an important and integral part of NASA's space exploration program. within this scope and context, our general effort is primarily aimed at developing glass and glass-ceramic type materials using Lunar and Martian soils and exploring various application potentials of these materials for planetary surface operations. This paper reports the successful preparation of glasses from the melts of simulated composition of Lunar and Martian soils, and thermal and structural characterization using differential thermal analysis (DTA), Mössbauer and electron paramagnetic resonance (EPR) spectroscopy. Glass-ceramic materials were developed from these glasses using selective …
Applications Of A Hybrid Manufacturing Process For Fabrication And Repair Of Metallic Structures, Frank W. Liou, Kevin P. Slattery, Mary Kinsella, Joseph William Newkirk, Hsin-Nan Chou, Robert G. Landers
Applications Of A Hybrid Manufacturing Process For Fabrication And Repair Of Metallic Structures, Frank W. Liou, Kevin P. Slattery, Mary Kinsella, Joseph William Newkirk, Hsin-Nan Chou, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Since its appearance, rapid prototyping technology has been of interest to various industries that are looking for a process to produce/build a part directly from a CAD model in a short time. Among them, the direct metal deposition process is the only process which directly manufactures a fully dense metal part without intermediate steps. However, challenges of the direct metal deposition process include building overhang structures, producing precision surfaces, and making parts with complex structures. Coupled between the additive and the subtractive processes into a single workstation, the integrated process, or hybrid process, can produce a metal part with machining …
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part I: Extrusion Process Modeling, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part I: Extrusion Process Modeling, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A novel, solid freeform fabrication method has been developed for the manufacture of ceramic-based components in an environmentally friendly fashion. The method is based on the extrusion of ceramic slurries using water as the binding media. Aluminum oxide (Al2O3) is currently being used as the part material and solids loading as high as 60 vol. % has been achieved. This paper describes a novel manufacturing machine that has been developed for the extrusion of high solids loading ceramic slurries. A critical component of the machine is the deposition system, which consists of a syringe, a plunger, …
Comparison Of Thermal Properties Of Laser Deposition And Traditional Welding Process Via Thermal Diffusivity Measurement, Yu Yang, Omoghene Osaze Obahor, Yaxin Bao, Todd E. Sparks, Jianzhong Ruan, Jacquelyn K. Stroble, Robert G. Landers, Joseph William Newkirk, Frank W. Liou
Comparison Of Thermal Properties Of Laser Deposition And Traditional Welding Process Via Thermal Diffusivity Measurement, Yu Yang, Omoghene Osaze Obahor, Yaxin Bao, Todd E. Sparks, Jianzhong Ruan, Jacquelyn K. Stroble, Robert G. Landers, Joseph William Newkirk, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser deposition is an effective process for mold and die repair. In order to improve the part repair quality, the process impact on thermal diffusivity and thermal conductivity needs to be understood for laser deposited, welded and virgin H13. In this paper, H13 tool steel samples were made by laser deposition, welding and virgin H13 and then cut into pieces. Experiments were conducted to investigate the thermal diffusivity and conductivity. A laser flash method is used to test these samples. The future work and opportunities are also summarized.
Evaluation Of Mechanical Properties And Microstructure For Laser Deposition Process And Welding Process, Yaxin Bao, Jianzhong Ruan, Todd E. Sparks, Jambunathan Anand, Joseph William Newkirk, Frank W. Liou
Evaluation Of Mechanical Properties And Microstructure For Laser Deposition Process And Welding Process, Yaxin Bao, Jianzhong Ruan, Todd E. Sparks, Jambunathan Anand, Joseph William Newkirk, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser Aided Manufacturing Process (LAMP) can be applied to repair steel die/molds which are currently repaired using traditional welding process in industry. In order to fully understand the advantages of laser deposition repair process over traditional welded-repair process, the mechanical properties such as tensile strength and hardness of H13 tool steel samples produced by these two processes were investigated. The microstructure and fracture surface of the samples were analyzed using optical microscope and SEM (Scanning Electron Microscope). Moreover, depositions on substrates with different shapes were studied to evaluate the performance of LAMP on damaged parts with complicated geometric shape.
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part Ii: Extrusion Process Control, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part Ii: Extrusion Process Control, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Part I of this paper provided a detailed description of a novel fabrication machine for high solids loading ceramic slurry extrusion processes and presented an empirical model of the ceramic extrusion process, viewing ram velocity as the input and extrusion force as the output. A constant extrusion force is desirable as it correlates with a constant material deposition rate and, thus, good part quality. The experimental results used to construct the model demonstrated that a constant ram velocity will not necessarily produce a constant extrusion force. In some instances the extrusion force increased until ram motor skipping occurred, and process …
Freeze-Spray Processing Of Layered Ceramic Composites, Qiang Fu, Oratai Jongprateep, Ashlee Abbott, Fatih Dogan
Freeze-Spray Processing Of Layered Ceramic Composites, Qiang Fu, Oratai Jongprateep, Ashlee Abbott, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
Thermal gradients and associated stresses are critical in designing with ceramic composites having low thermal conductivity. In order to reduce the stresses from thermal gradients, compositional gradients are employed in designing of composite structures. This study addresses development of freeze-spray process to fabricate layered ceramic structures with controlled layer thickness and microstructural development. The composites were processed by spraying of ceramic slurries with low binder content and relatively high solids loadings (up to 40 vol%) on a cooled substrate. The frozen parts were freeze-dried and sintered at elevated temperatures. The relationship between microstructural development and thermal expansion behavior of Al …
Method For Fabricating Nanostructured Solid Oxide Fuel Cells And Cell Components, Harlan U. Anderson, X.-D. Zhou, Wayne Huebner
Method For Fabricating Nanostructured Solid Oxide Fuel Cells And Cell Components, Harlan U. Anderson, X.-D. Zhou, Wayne Huebner
Materials Science and Engineering Faculty Research & Creative Works
A method of fabricating a nanostructured solid oxide fuel cell includes dispersing ceria and doped ceria nanoparticles in a first colloidal solution, atomizing the first colloidal solution into a spray, depositing the spray onto a substrate to form a thin film electrolyte, dispersing a nanocomposite powder including ceria and CuO in the first solution, forming a second colloidal solution, atomizing the second colloidal solution into a second spray, and depositing the second spray over the thin film electrolyte as an interfacial layer.
Method Of Preparing A Solid Oxide Fuel Cell, Greg Hilmas, Dustin Beeaff
Method Of Preparing A Solid Oxide Fuel Cell, Greg Hilmas, Dustin Beeaff
Materials Science and Engineering Faculty Research & Creative Works
A solid oxide fuel cell having a multichannel electrode architecture and method for preparing the same, the method including forming a first carbon laden composition, including a first thermoplastic binder, into a rod, applying a first zirconia laden composition, including a second thermoplastic binder, onto the rod to form a composite feed rod, extruding the composite feed rod to form a controlled geometry filament, bundling the extruded composite feed rod to form a multicellular feed rod, extruding the multicellular feed rod to form a multicellular rod, cutting the multicellular rod into multicellular discs, applying a zirconia laden material to one …
Inelastic Deformation Behavior Of La0.6sr0.4feo3 Perovskite, Nina Orlovskaya, Harlan U. Anderson, Mykola Brodnikovskyy, Mykola Lugovy, Michael John Reece
Inelastic Deformation Behavior Of La0.6sr0.4feo3 Perovskite, Nina Orlovskaya, Harlan U. Anderson, Mykola Brodnikovskyy, Mykola Lugovy, Michael John Reece
Materials Science and Engineering Faculty Research & Creative Works
Inelastic deformation behavior of the rhombohedral La0.6Sr0.4FeO3 perovskite is reported. Such behavior is very similar to the ferroelastic deformation of LaCoO3 or lead zirconate titanate perovskites, except that no twin structure was found to exist in La0.6Sr0.4FeO3. the possible mechanisms responsible for such nonlinear deformation behavior are discussed. © 2006 American Institute of Physics.
Application Of Chip-Level Emc In Automotive Product Design, Kuifeng Hu, H. Weng, Daryl G. Beetner, David Pommerenke, James L. Drewniak, K. Lavery, Jason Whiles
Application Of Chip-Level Emc In Automotive Product Design, Kuifeng Hu, H. Weng, Daryl G. Beetner, David Pommerenke, James L. Drewniak, K. Lavery, Jason Whiles
Electrical and Computer Engineering Faculty Research & Creative Works
Integrated circuits (ICs) are often the source of the high-frequency noise that drives electromagnetic emissions from electronic products. A case study is presented where emissions from a printed circuit board containing an automotive microcontroller are reduced significantly through analysis of the coupling mechanisms from the chip to the board and attached cables. Noise generated by the IC is explored through measurements in a semi-anechoic chamber and TEM cell, through near-field scans, and through modifications to the printed circuit board. Noise is driven by the IC through both power and I/O connections. Results show that a ferrite in series with I/O …
Dielectric Constant Of Particles Determined By Impedance Spectroscopy, Vladimir Petrovsky, Abhishek Manohar, Fatih Dogan
Dielectric Constant Of Particles Determined By Impedance Spectroscopy, Vladimir Petrovsky, Abhishek Manohar, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
Electrical characterization of slurries prepared by mixing dielectric powders with solvents can be used to estimate dielectric properties of the particles. In particular, dielectric constant of the particles can be calculated from effective dielectric constant of the slurry measured at high frequency by using the Lorentz-Lorenz or similar equations based on mixing rules. Unfortunately, this approach leads to high margin of errors in dielectric constant estimation and is very sensitive to any slurry nonidealities such as sedimentation or agglomeration of particles. Impedance spectroscopy techniques are introduced to measure dielectric properties of particles at different frequency ranges. Dielectric constant of strontium …
Cerium-Based Spontaneous Coating Process For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Matthew O'Keefe, Eric L. Morris, Scott A. Hayes, Paul Yu, Alex Williams, Berny F. Rivera Vasquez, Xuan Lin
Cerium-Based Spontaneous Coating Process For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Matthew O'Keefe, Eric L. Morris, Scott A. Hayes, Paul Yu, Alex Williams, Berny F. Rivera Vasquez, Xuan Lin
Chemistry Faculty Research & Creative Works
A cerium-based coating for corrosion resistance is applied by exposing a cleaned aluminum-based component to a corrosion-inhibiting cerium solution containing cerium ions in the presence of an oxidizing agent. The coating deposits spontaneously without an external source of electrons.
Simulations Of A New Continuous Steelmaking Process, Jorg Annie Peter, Kent D. Peaslee, D. G. C. Robertson
Simulations Of A New Continuous Steelmaking Process, Jorg Annie Peter, Kent D. Peaslee, D. G. C. Robertson
Materials Science and Engineering Faculty Research & Creative Works
A new continuous steelmaking process has been designed in an effort to reduce meltshop costs and increase productivity beyond the possibilities of current EAF-LMF-CC meltshops. This paper discusses possible operational performance based on industrially-verified kinetic, thermodynamic, and heat-transfer models. Dynamic simulations predict variations in steel chemistry and temperature, resulting from steel treatment and upsets. Savings in costs are projected because of increased metallic yield, lower energy requirements, more efficient use of deoxidants and alloys, fewer man-hours per ton, and decreased capital investment.
2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla
2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla
Undergraduate Research Conference at Missouri S&T
No abstract provided.
Method And Apparatus For Solder-Less Attachment Of An Electronic Device To A Textile Circuit, James A. Zollo, Bonnie Bachman, Alan R. Beatty, Stephen O. Bozzpme, Nitin B. Desai, Ronald J. Kelley, Rami C. Levy
Method And Apparatus For Solder-Less Attachment Of An Electronic Device To A Textile Circuit, James A. Zollo, Bonnie Bachman, Alan R. Beatty, Stephen O. Bozzpme, Nitin B. Desai, Ronald J. Kelley, Rami C. Levy
Economics Faculty Research & Creative Works
A method and apparatus form electrical connections between electronic circuits and conductive threads (102, 104, 106, 108) that are interwoven into textile material (130). Electronic circuits (128), such as semiconductor dies, are connected to a carrier (132) and electrical connections (136) are made to conductive connection areas (110, 112, 114, 116) on the carrier (132). Conductive stitching (202, 204, 206, 208) provides electrical contacts for both the conductive connection areas (110, 112, 114, 116) on the carrier (132) and the conductive threads (102, 104, 106, 108) that are interwoven into the textile material (130). Optionally, a thin, flexible substrate material …
Method For Preparation Of Nanometer Cerium-Based Oxide Particles, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson
Method For Preparation Of Nanometer Cerium-Based Oxide Particles, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson
Materials Science and Engineering Faculty Research & Creative Works
The invention comprises novel undoped and doped nanometer-scale CeO2 particles as well as a novel semi-batch reactor method for directly synthesizing the novel particles at room temperature. The powders exhibited a surface area of approximately 170 m2/g with a particle size of about 3-5 nm, and are formed of single crystal particles that are of uniform size and shape. The particles’ surface area could be decreased down to 5 m2/g, which corresponds to a particle size of 100 nm, by thermal annealing at temperatures up to 1000° C. Control over the particle size, size distribution …
The Phase Stability Of Cerium Species In Aqueous Systems Iii. The Ce(Iii/Iv)-H2o-H2o2/O2 System Dimeric Ce(Iv) Species, Pu Yu, Thomas J. O'Keefe
The Phase Stability Of Cerium Species In Aqueous Systems Iii. The Ce(Iii/Iv)-H2o-H2o2/O2 System Dimeric Ce(Iv) Species, Pu Yu, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
Equilibria and thermodynamic data for cerium dimer species were calculated for both the Ce-H2O-O2 and Ce-H2O-H2O2 systems. It was found that Ce (IV) has a tendency to form dimers, especially when the total cerium concentration is higher than 0.001 M. There are three major soluble dimer forms considered in this paper: (CeOCe)6+,(CeOCe)(OH)5+, and (CeOCe)(OH)24+, all having very similar standard potentials (E0 Ce(IV)dimer/Ce(III)01.66∀0.02V). When they coexist in solution, the concentration ratio of the Ce (IV) dimer to Ce3+ depends on the total cerium concentrations, the …
Structural And Magnetic Properties Of La Mn₁₋ₓfeₓo₃ (0 < X < 1.0), X.-D. Zhou, L. R. Pederson, Qingsheng Cai, Jinbo Yang, B. J. Scarfino, M. Kim, William B. Yelon, William Joseph James, Harlan U. Anderson, C. Wang
Structural And Magnetic Properties Of La Mn₁₋ₓfeₓo₃ (0 < X < 1.0), X.-D. Zhou, L. R. Pederson, Qingsheng Cai, Jinbo Yang, B. J. Scarfino, M. Kim, William B. Yelon, William Joseph James, Harlan U. Anderson, C. Wang
Materials Science and Engineering Faculty Research & Creative Works
Electronic, structural, and magnetic properties of Mn-doped lanthanum ferrites were studied by neutron diffraction, superconducting quantum interference device, and impedance spectroscopy. Neutron diffraction refinements were performed with the constraint of full La occupancy, which showed the presence of excess oxygen when x < 0.4. Mixed valent Mn cations and cation vacancies, therefore, exist in all the samples. The samples with x > 0.7 are magnetically ordered at room temperature with orthorhombic symmetry (Pbnm). When x < 0.3 the structure is rhombohedral and magnetically disordered above 16 K. The majority carriers, electron holes, correspond to high oxidation states of Mn. The carrier concentration is determined from the Seebeck coefficients, and is a function of temperature and Fe concentration. The measurements of conductivity and Seebeck coefficients show polaron hopping at elevated temperatures.
Fusion Of Microwave And Eddy Current Data For A Multi-Modal Approach In Evaluating Corrosion Under Paint And In Lap Joints, Kapil Gupta, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, R. Joe Stanley, Ajay Padwal, Matthew O'Keefe, Donald D. Palmer, J. Blackshire, Gary Steffes, N. Wood
Fusion Of Microwave And Eddy Current Data For A Multi-Modal Approach In Evaluating Corrosion Under Paint And In Lap Joints, Kapil Gupta, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, R. Joe Stanley, Ajay Padwal, Matthew O'Keefe, Donald D. Palmer, J. Blackshire, Gary Steffes, N. Wood
Electrical and Computer Engineering Faculty Research & Creative Works
Critical aircraft structures are susceptible to hidden corrosion. Find-it and fix-it approaches are inefficient as it relates to managing the problems associated with corrosion. More comprehensive corrosion information may be obtained using data fusion from several detection and evaluation methods. To this end, microwave, conventional and pulsed eddy current data from a multi-layer corroded panel, representing an aircraft lap joint, are fused and used as inputs to a structural analysis model to obtain a comprehensive snapshot of the corroded environment. This paper presents the data fusion algorithm and the structural analysis model along with a discussion of the results.
Millimeter Wave Imaging Of Corrosion Under Paint: Comparison Of Two Probes, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, Matthew O'Keefe, Ajay Padwal, Donald D. Palmer
Millimeter Wave Imaging Of Corrosion Under Paint: Comparison Of Two Probes, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, Matthew O'Keefe, Ajay Padwal, Donald D. Palmer
Electrical and Computer Engineering Faculty Research & Creative Works
Critical aircraft structures are susceptible to harsh environmental conditions that cause corrosion of these structural components. It is of great importance to detect corrosion under paint, particularly in its early stages. Millimeter wave nondestructive evaluation methods have shown great potential for detecting corrosion under paint and evaluating its properties. This paper presents and compares the results of using two distinct millimeter wave detection methods; namely a standard single probe and a newly developed differential probe for detecting corrosion under paint.
Redox Stable Electrodes For Hydrogen Producing Solid Oxide Electrolyzer, Yong Wook Sin, Vladimir Petrovsky, Harlan U. Anderson
Redox Stable Electrodes For Hydrogen Producing Solid Oxide Electrolyzer, Yong Wook Sin, Vladimir Petrovsky, Harlan U. Anderson
Materials Science and Engineering Faculty Research & Creative Works
This report focuses on a study which measured the electrical conductivity of LSCrM, LSCr and LSM as a function of oxygen activity and temperature to evaluate the chemical and mechanical stability of the materials as an electrode in a solid oxide fuel-fed electrolyzer cell (SOFEC). the LSCrM symmetrical cell was fabricated using La0.75Sr0.25Cr0.5Mn0.5O3 (LSCrM) powder and evaluated using electrical conductivity, impedance spectroscopy, current density and power density as a function of temperature. during the evaluation, symmetrical cell tests and fuel cell tests were performed as a function of temperature. Silver (Ag) …
Maxwell-Wagner Relaxations And Their Contributions To The High Permittivity Of Calcium Copper Titanate Ceramics, Wei Li, Robert W. Schwartz
Maxwell-Wagner Relaxations And Their Contributions To The High Permittivity Of Calcium Copper Titanate Ceramics, Wei Li, Robert W. Schwartz
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Calcium copper titanate ceramics were fabricated by cold isostatic pressing at various calcination and sintering conditions. Depending on fabrication condition, three electrical responses were observed in the combined modulus and impedance plots, indicating the presence of two Maxwell-Wagner relaxations. These electrical responses show different response to temperature and applied field. The activation energies, as well as the driving force factors, were calculated for these relations. The determined activation energy values are in the range of 0.57 to 0.65 eV. The contribution of Maxwell-Wagner relaxations to the high permittivity of CCTO and related materials is briefly discussed.
Segmental Mobility Of Chain Ends In Poly(Methyl Acrylate)-D3, Burak Metin, Frank D. Blum
Segmental Mobility Of Chain Ends In Poly(Methyl Acrylate)-D3, Burak Metin, Frank D. Blum
Chemistry Faculty Research & Creative Works
Better control of polymeric materials can be achieved with a thorough understanding of the dynamics of their constituents. In the present study, we consider polymer chains as composed of chain middles and chain ends. Even though chain ends do not comprise much of the sample by mass, they may play a crucial role in the ultimate properties of the polymers. Although chain ends have been assigned a higher mobility, as compared to chain middles, there have not been a large number of experimental studies that directly probe their mobility. Among those, the studies of Kitahara et al.1 and Miwa et …
Modeling Of Dielectric Mixtures Containing Conducting Inclusions With Statistically Distributed Aspect Ratio, Marina Koledintseva, Sandeep K. R. Chandra, Richard E. Dubroff, Robert W. Schwartz
Modeling Of Dielectric Mixtures Containing Conducting Inclusions With Statistically Distributed Aspect Ratio, Marina Koledintseva, Sandeep K. R. Chandra, Richard E. Dubroff, Robert W. Schwartz
Electrical and Computer Engineering Faculty Research & Creative Works
An analytical model of composites made of a dielectric base and randomly oriented metal inclusions in the form of nanorods is presented. This model is based on the generalized Maxwell Garnett (MG) mixing rule. In this model, the nanorod particles are modeled as prolate spheroids with a statistically normal distribution of their aspect ratios. It is shown that parameters of the distribution laws affect the frequency characteristics of the composites both at microwave and optical frequencies. The results of computations are represented.