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Articles 1 - 8 of 8
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Lignin Yield Maximization Of Lignocellulosic Biomass By Taguchi Robust Product Design Using Organosolv Fractionation, Anton Friedrich Astner
Lignin Yield Maximization Of Lignocellulosic Biomass By Taguchi Robust Product Design Using Organosolv Fractionation, Anton Friedrich Astner
Masters Theses
Lignin, a byproduct of the organosolv pretreatment process using lignocellulosic biomass from switchgrass (Panicum virgatum) and tulip poplar (Liriodendron tulipifera) is currently being explored for its potential use in the production of value-added chemicals and biobased polymers. Pretreatment is one of the most expensive processing steps in cellulosic biomass conversion. Optimization of the process is one of the major goals of the biomass-toethanol conversion process. Taguchi Robust Product Design (TRPD) provides an effective engineering experimental design method for optimizing a system and designing products that are robust to process variations. Given the results of several preliminary …
Fatigue Behavior Of High-Entropy Alloys, Michael Alexander Hemphill
Fatigue Behavior Of High-Entropy Alloys, Michael Alexander Hemphill
Masters Theses
Research was performed on the Al9Co18.2Cr18.2Cu18.2Fe18.2Ni18.2 [subscripts atomic percent] and Al7.5Cr22.5Fe35Mn20Ni15 high-entropy alloys (HEAs) in an attempt to study their fatigue behavior. The present investigation shows encouraging fatigue-resistance characteristics due to their high fatigue lives of various samples at relatively high stresses. The current results indicate that the fatigue behavior of HEAs compares favorably to many conventional alloys, such as steels, titanium alloys, and advanced bulk metallic glasses with a fatigue-endurance limit of the Al9Co18.2Cr18.2 …
Processing, Microstructures, And Mechanical Behavior Of High-Entropy Alloys, Zhi Tang
Processing, Microstructures, And Mechanical Behavior Of High-Entropy Alloys, Zhi Tang
Masters Theses
Recently, high-entropy alloys (HEAs) have attracted increasing attentions because of their unique compositions, microstructures, and adjustable properties. In this work, microstructure and phase composition of the AlCoCrFeNi high-entropy alloy (HEA) were studied in as-cast and heat-treated conditions. Using a combination of Electron Backscatter Diffraction (EBSD), X-ray energy spectroscopy analysis, and synchrotron X-ray diffraction techniques, two nonequilibrium phases were identified in the as-cast condition: BCC_A2 and B2. Long-term heat treatment transformed these nonequilibrium phases into four equilibrium phases: FCC_A1, BCC_A2, B2, and σ [sigma] phase. The electron microscopic results were consistent with thermodynamic simulations of the equilibrium …
Development And Use Of A Simple Test Method To Evaluate Reheat Cracking Sensitivity In The Weld Deposit Region Of A Submerged Arc Weld, Maxwell Calder Trent
Development And Use Of A Simple Test Method To Evaluate Reheat Cracking Sensitivity In The Weld Deposit Region Of A Submerged Arc Weld, Maxwell Calder Trent
Masters Theses
Several fabricators have recently noted the occurrence of reheat cracking in the weld deposits of 2¼[ two and one fourth]Cr‑1Mo‑¼[one fourth]V (22V) during the fabrication of pressure vessels used in the petrochemical industry. Due to increased oversight now required during fabrication of already expensive pressure vessels, studies have commenced worldwide in an effort to identify root causes and formulate mitigating actions to weld reheat cracking issues. The Materials Joining Group (MJG) at the University of Tennessee at Knoxville (UTK) have adapted an existing reheat cracking test originally developed for use with alloys similar to 22V. This original C‑Ring test was …
Pretreatment And Pyrolysis Of Rayon-Based Precursor For Carbon Fibers, Kokouvi Akato
Pretreatment And Pyrolysis Of Rayon-Based Precursor For Carbon Fibers, Kokouvi Akato
Masters Theses
In this work, two rayon fibers were investigated as carbon fiber precursors. A detailed consideration has been applied to a domestically produced cellulose fiber to carbon fiber (CF) transition. This transition of precursor to carbon fiber can be subdivided into two stages: pyrolysis (thermal decomposition) of cellulose in air and high temperature treatment in an inert atmosphere. The specific objectives were to investigate the stabilization stage of the produced rayon with respect to changes taking place during thermal decomposition, and to evaluate the effects on the properties of the carbonized fiber. Changes taking place during the conversion process of the …
Reduced Leak Calibration Uncertainties By The Outgassing Quantification Method, Philip Mason Carper
Reduced Leak Calibration Uncertainties By The Outgassing Quantification Method, Philip Mason Carper
Masters Theses
Standard leaks are used throughout industry for various applications, such as gas transfer, calibration of mass spectrometers, and calibration of leak detectors. The ability to provide a controlled delivery of gases at relatively low flow rates makes standard leaks a popular choice for calibration standards. This ability also allows for precise quantities of gas to accumulate over time. The accumulation of gas from standard leaks is used as a “transfer standard” for making in-process adjustments to measurement instrumentation. With the advent of tighter quality control constraints, the quantification and control of leak rates is becoming an increasingly important matter, placing …
Compatibility Evaluation Of Glass/Epoxy Insulation For Use In Iter’S Central Solenoid Superconducting Electromagnets, Carolyn Grace Kidwell
Compatibility Evaluation Of Glass/Epoxy Insulation For Use In Iter’S Central Solenoid Superconducting Electromagnets, Carolyn Grace Kidwell
Masters Theses
A variety of glass fiber types are being considered for use as insulation material in the central solenoid superconducting electromagnets for the International Thermonuclear Experimental Reactor (ITER). Before these materials can be used, a compatibility of these glass products with an epoxy matrix has to be characterized. In this study, three candidate glass types (1581, 7781, and 38050) were considered and their compatibility with a DGEBF epoxy matrix was determined via three-point flexure tests at room temperature (295K) and liquid nitrogen temperature (77K) and constant load flexure creep tests at room temperature. The material variables among these glass products were …
Thermodynamic Analysis Of Polyethylene Glycol Thiol-Ene Click Chemistry And Surface Modification Of Bacterial Cellulose, Kaan Serpersu
Thermodynamic Analysis Of Polyethylene Glycol Thiol-Ene Click Chemistry And Surface Modification Of Bacterial Cellulose, Kaan Serpersu
Masters Theses
Polyethylene glycol (PEG) has been one of the extensively studied polymers for medical applications. However, the use of PEG can require complicated and low efficiency reactions which can impose limits to potentially useful medical solutions. Click chemistry has recently emerged as a way to avoid these pitfalls by utilizing reactions that are highly efficient and require simple reaction conditions. One such reaction is known as the Michael-addition thiol-ene click reaction (TECC). The combination of PEG with TECC has received some study, but has not been thermodynamically characterized as a click reaction. In this work PEG-TECC reaction kinetics were studied by …