New Technologies In Underground Projects: Drill Core Scanning, Documentation And Analysis, Jens Wiegand

Shotcrete for Underground Support XII

No abstract provided.

The Effect Of Spraying On Fiber Content And Shotcrete Properties, Marc Jolin, J.-D. Lemay, N. Ginouse, B. Bissonnette, É. Blouin-Dallaire

Shotcrete for Underground Support XII

No abstract provided.

Influence Of Calcium Sulfoaluminate Cement On The Pullout Performance Of Reinforcing Fibers: An Evaluation Of The Micro-Mechanical Behavior, Robert B. Jewell

Theses and Dissertations--Civil Engineering

The objective of this research was to determine the influence of calcium sulfoaluminate (CSA) cement on reinforcing fibers by evaluating the fiber pullout behavior, and bonding characteristics, of a single fiber embedded in a cementitious paste matrix. Four types of fibers commonly used in industry were evaluated: 1) Polyvinyl alcohol; 2) Polypropylene; 3) Coated Steel; and 4) Plain Steel.

Upward trends in energy costs and potential greenhouse gas regulations favor an increased use of construction materials that require lower energy and lower CO₂ emissions to fabricate, such as CSA cement, as opposed to the production of ordinary portland cement …

Effects Of Magnetic Field On The Shape Memory Behavior Of Single And Polycrystalline Magnetic Shape Memory Alloys, Ali S. Turabi

Theses and Dissertations--Mechanical and Aerospace Engineering

Magnetic Shape Memory Alloys (MSMAs) have the unique ability to change their shape within a magnetic field, or in the presence of stress and a change in temperature. MSMAs have been widely investigated in the past decade due to their ability to demonstrate large magnetic field induced strain and higher frequency response than conventional shape memory alloys (SMAs). NiMn-based alloys are the workhorse of metamagnetic shape memory alloys since they are able to exhibit magnetic field induced phase transformation. In these alloys, martensite and austenite phases have different magnetization behavior, such as the parent phase can be ferromagnetic and martensite …

Shape Memory Behavior Of Single Crystal And Polycrystalline Ni-Rich Nitihf High Temperature Shape Memory Alloys, Sayed M. Saghaian

Theses and Dissertations--Mechanical and Aerospace Engineering

NiTiHf shape memory alloys have been receiving considerable attention for high temperature and high strength applications since they could have transformation temperatures above 100 °C, shape memory effect under high stress (above 500 MPa) and superelasticity at high temperatures. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf alloys have some drawbacks such as low ductility and high work hardening in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing.

Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti29.3Hf20, …

Development Of Multifunctional Shape Memory Polymer And Shape Memory Polymer Composites, Sesha Spandana Pulla

Theses and Dissertations--Mechanical and Aerospace Engineering

Shape memory polymers (SMPs) are an emerging class of active polymers that can be used on a wide range of reconfigurable structures and actuation devices. The present study comprehensively examines the unconstrained shape recovery abilities of an epoxy-based SMP. In doing so, epoxy based SMP is synthesized and thermo-mechanically characterized. Results show that the present SMP exhibits excellent shape recoveries under unconstraint conditions, for a range of fixing strains and temperatures. Additionally, the stress-strain behavior of the SMP is determined to be nonlinear, finite deformation at all regions. The strain energy based models have been used to capture the complicate …

Adsorption Behaviour Of Polyacrylic Acid On Cerium Oxide Nanostructures: Experimental And Predictive Model, Ali Haghighat Mesbahi

Electronic Theses and Dissertations

Cerium oxide-based slurries are crucial for chemical mechanical polishing (CMP) in electronic industry. For these slurry systems, poly(acrylic acid) (PAA) is heavily utilized to provide colloidal stability. Some of the important parameters in the colloid stability are molecular weight (MW) and concentration of stabilizer, size of the nanoparticle in the slurry and the pH of system. By determining the colloidal stability of a discrete number of slurry formulations and relating these to certain slurry component parameters, a possible model can be produced to predict the influence of these parameters on the particle stability. Direct quantification of colloidal stability is difficult, …

Porosity Removal Of Cm247 Ni-Base Superalloy Using Thermal Heat Treatment Without Applied Pressure, Chad Heinrich

Electronic Theses and Dissertations

Blade and vane components made with Ni-base superalloys play a vital role in hot section of gas turbine engines. Removal of porosity in cast Ni-base superalloys is a critical process consideration since porosity from casting process can have deleterious effects on the performance and integrity of superalloy component. Still, the cost-efficient processing of Ni-base superalloys that are technologically acceptable, or superior, can contribute significantly to the life-cycle cost of gas turbine engines. The purpose of this thesis was to explore the possibility of eliminating the hot isostatic pressing cycle in a CM247 Ni-base superalloy processing. For cast CM247, conventional processing …

Phase Transformations And Microstructural Evolution In The U-10 Wt.% Mo Alloy With Various Zr Additions At 900c And 650c, Nicholas Eriksson

Electronic Theses and Dissertations

The Reduced Enrichment for Research and Test Reactor (RERTR) now known as the Material Minimization and Management Reactor Control program (MMMRC) seeks to replace the use of highly enriched uranium (HEU) fuels used in research and test nuclear reactors around the world. The low enriched uranium (LEU) fuels must have fissionable uranium densities comparable to the HEU fuels. After extensive investigation by various researchers around the world, the U-Mo alloys were selected as a promising candidate. The Mo alloyed with U allows for the stabilization of the face-centered cubic ?-U phase, which demonstrated favorable irradiation behavior. However, deleterious diffusional interaction …

The Future Of Carbon-Based Scaffolds In Foot And Ankle Surgery, Jarema S. Czarnecki, Khalid Lafdi, Panagiotis A. Tsonis

Chemical and Materials Engineering Faculty Publications

Autologous grafts have been the gold standard in tissue replacement and the most accurate means of recapitulating both the biological and mechanical properties of tissue. However, autologous grafts have had complications and drawbacks. Skin grafting, a prime example of an autologous tissue graft, has been limited by the size of graft, availability, and secondary donor site morbidity. Use of cadaveric tissues circumvents several limitations of autologous grafts; however, sterilization processes used to reduce the risk of disease transmission potentially weaken tissues and eliminate living cells and some growth factors from scaffolds, making them suboptimal tissue replacements. Chemical cross-linkage of tissue …

Effects Of Disorder State And Interfacial Layer On Thermal Transport In Copper/Diamond System, Vikas Sinha, Jaime J. Gengler, Christopher Muratore, Jonathan E. Spowart

Chemical and Materials Engineering Faculty Publications

The characterization of Cu/diamond interface thermal conductance (h_c) along with an improved understanding of factors affecting it are becoming increasingly important, as Cu-diamond composites are being considered for electronic packaging applications. In this study, ∼90 nm thick Cu layers weredeposited on synthetic and natural single crystal diamond substrates. In several specimens, a Ti-interface layer of thickness ≤3.5 nm was sputtered between the diamond substrate and the Cu top layer. The h_c across Cu/diamond interfaces for specimens with and without a Ti-interface layer was determined usingtime-domain thermoreflectance. The h_c is ∼2× higher for similar interfacial layers on …

Self-Assembly Kinetics Of Microscale Components: A Parametric Evaluation, Jose Miguel Carballo

USF Tampa Graduate Theses and Dissertations

The goal of the present work is to develop, and evaluate a parametric model of a basic microscale Self-Assembly (SA) interaction that provides scaling predictions of process rates as a function of key process variables. At the microscale, assembly by “grasp and release” is generally challenging. Recent research efforts have proposed adapting nanoscale self-assembly (SA) processes to the microscale. SA offers the potential for reduced equipment cost and increased throughput by harnessing attractive forces (most commonly, capillary) to spontaneously assemble components. However, there are challenges for implementing microscale SA as a commercial process. The existing lack of design tools prevents …

Understanding The Role Of Colloidal Particles In Electroporation Mediated Delivery, Alisha Peterson

USF Tampa Graduate Theses and Dissertations

Electroporation (EP) is a physical non-viral technique used to deliver therapeutic molecules across the cell membrane. During electroporation an external electric field is applied across a cell membrane and it causes pores to form. These pores then allow the surrounding media containing the therapeutics to diffuse across the membrane. This technique has been specifically studied as a promising gene and drug delivery system. Colloidal particles have also proven to be promising for a variety of biological applications including molecular delivery, imaging, and tumor ablation, due to their large surface area and tunable properties. In more recent years researchers have explored …

Systems Approach To Producing Electrospun Polyvinylidene Difluoride Fiber Webs With Controlled Fiber Structure And Functionality, Brian D. Bell

USF Tampa Graduate Theses and Dissertations

Polyvinylidene difluoride (PVDF) is a functional polymeric material that can be used for a wide variety of applications. There are many new future applications that were recently suggested for electrospun PVDF fibers. Electrospinning is a process capable of producing nano to micro sized PVDF fibers in a web. It is important to control the structure of the web during electrospinning because by controlling the structure of the web it is possible for the PVDF fiber web to have increased performance in comparison to other common forms of PVDF.

While past scientific literature focused on applications of PVDF fibers, little was …

Computational Study Of Microstructure-Propertymechanism Relations In Ferroic Composites, Fengde D. Ma

Dissertations, Master's Theses and Master's Reports - Open

Ferroic materials, as notable members of smart materials, have been widely used in applications that perform sensing, actuation and control. The macroscopic property change of ferroic materials may become remarkably large during ferroic phase transition, leading to the fact that the macroscopic properties can be tuned by carefully applying a suitable external field (electric, magnetic, stress). To obtain an enhancement in physical and/or mechanical properties, different kinds of ferroic composites have been fabricated. The properties of a ferroic composite are determined not only by the properties and relative amounts of the constituent phases, but also by the microstructure of individual …

Modeling And Simulation Of Microstructures, Mechanisms, And Diffraction Effects In Energy Materials: Ferroelectrics And Lithium Ion Battery Cathode Materials, Jie Zhou

Dissertations, Master's Theses and Master's Reports - Open

Ferroelectric materials, as a large family exploited for the application of sensors, transducers and random access memories, open up a remarkable ground both for fundamental science and industry. Dielectric and piezoelectric properties are of the most interest in ferroelectric materials, which motivate research to enhance ferroelectric properties based on various application purposes. Among the multitudinous candidates in ferroelectric family, pseudo binary solid solutions with ABO₃ lattice structure attract special attention in virtue of their large strain response when applying external loading. Furthermore, existence of morphological phase boundary (MPB) on their phase diagrams shed light on tuning material compositions to …

Structures, Properties And Functionalities Of Magnetic Domain Walls In Thin Films, Nanowires And Atomic Chains: Micromagnetic And Ab Initio Studies, Liwei D. Geng

Dissertations, Master's Theses and Master's Reports - Open

Structures, properties and functionalities of magnetic domain walls in thin film, nanowires and atomic chains are studied by micromagnetic simulations and ab initio calculations in this dissertation. For magnetic domain walls in thin films, we computationally investigated the dynamics of one-dimensional domain wall line in ultrathin ferromagnetic film, and the exponent α = 1.24 ± 0.05 is obtained in the creep regime near depinning force, indicating the washboard potential model is supported by our simulations. Furthermore, the roughness, creep, depinning and flow of domain wall line with commonly existed substructures driven by magnetic field are also studied. Our simulation results …

Effect Of Nanofiber Morphology On Pvdf Air Filter Performance, Andrew W. Marton

Williams Honors College, Honors Research Projects

Poly(vinylidene fluoride) (PVDF) can be formed into small nanofibers by electrospinning that are useful for a variety of applications. Air filters produced with PVDF are known to capture ionic particles with high efficiency. Existing studies have focused on the effects of electrospinning conditions on nanofiber morphology. In this study fibers were generated with varying morphologies. Air filters were then made from each sample and then characterized by TSI. Air filters were found to have increased resistances relative to their capture efficiencies according to particle diameter. Capture efficiencies did not correlate strongly with particle diameter, and the presence of beads in …

Design Of The University Of Akron's 2015 Fsae Electric Vehicle Braking System, Nicholas D. Galbincea

Williams Honors College, Honors Research Projects

The following report encompasses the design of the 2015 University of Akron’s FSAE formula electric braking system. The system is one based on hydraulic braking and designed for a one man performance racing vehicle. The objective of the system is to convert the kinetic energy of the vehicle into thermal energy, allowing the vehicle to decelerate optimally and safely. The design includes three major categories: calculation and evaluation of the hydraulic system in order to select calipers and master cylinders, the design of the pedal box, and the design of the rotors.

The results and findings of the proceeding report …

Reusable Adhesive Tapes From Electrospun Polymer Fibers, Vishal K. Chaurasia

Williams Honors College, Honors Research Projects

Many emerging applications demand an adhesive that has reusable properties. The adhesive must exhibit high adhesion strength to various surfaces and be able to be removed easily and then reapplied with minimal to no loss in adhesion strength. This work aims to tackle this problem by creating an adhesive tape fabricated by electrospinning polymer solutions onto a substrate. Electrospun adhesive nano/micro fibers have the ability to display the reusable characteristics desired. Several adhesive custom formulations were first developed and optimized for electrospinning. Then these formulations were successfully electrospun on to various substrates after much fine tuning of electrospinning parameters. The …

Nylon-6 Fabric Nanocomposite Resistance Temperature Detectors - Effects Of Oxidant, Mwcnt, And Nylon-6 Concentration, Rebecca Howdyshell

Williams Honors College, Honors Research Projects

Abstract

The purpose of this honors project is to construct and test temperature detectors, which can be used for the advancement of exercise devices, prosthetic sockets, or medical applications. Resistance Temperature Detectors (RTDs) are an effective way to measure temperature due to the dependence of the RTD material’s resistance on temperature. The focus of this project was to develop an RTD for prosthetic socket or exercise applications, where the RTD is in close contact with the skin of the user. Generally, RTDs are constructed from platinum, copper, or nickel. However, metal RTDs have a tendency to be large and rigid, …

The Examination Of Stress Corrosion Cracking In High Strength Carbon Steel Through Combined Mechanical-Electrochemical Testing, Jacob Sines

Williams Honors College, Honors Research Projects

Through the analysis of materials and environments seen in industry a better understanding of the fundamentals behind degradation mechanisms can be observed. The scope of this project was to better understand the fundamentals behind the degradation of high strength pipeline steels in a lab setting to simulate an environment seen in industry. Specifically the degradation mechanisms of high and nearly neutral pH stress corrosion cracking were examined in environments that simulated oil and gas pipelines buried in soil. Experimentation was carried out utilizing X65 carbon steel specimen, a Gamry potentiostat, a CORTEST proof ring, a CORTEST slow strain rate machine, …

Rheology Of Cross-Linked Polymers And Polymer Foams: Theory And Experimental Results, John Herman

Wayne State University Dissertations

Typical polymers have a time-dependent response to loading which results in stress relaxation or creep. Models using springs/dashpots or Volterra integrals are capable of predicting the material response, but place little or no emphasis on the reasoning behind the response. This research proposes a microscopic reasoning behind polymer chain movement, while developing a model to predict the creep and stress relaxation of a polymer foam. Based on the theorized slip/stick of polymer chains as they slide past each other, this model successfully predicts the behavior of a PMI polymer foam under tensile loads. This model lends insights into polymer microscopic …

Composition- And Pressure-Induced Ferroelectric To Antiferroelectric Phase Transitions In Sm-Doped Bifeo₃ System, Fei Xue, Linyun Liang, Yijia Gu, Ichiro Takeuchi, Sergei V. Kalinin, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

A three-dimensional phenomenological model is proposed to describe both ferroelectricity and antiferroelectricity based on the Ginzburg-Landau-Devonshire theory. Its application to the multiferroic Sm-doped BiFeO₃ system describes the temperature-, pressure-, and composition-induced ferroelectric to antiferroelectric phase transitions. The constructed temperature-composition and temperature-pressure phase diagrams show that compressive hydrostatic pressure and Sm doping have similar effects on the ferroelectric and antiferroelectric phase transitions. It is also indicated from the temperature-pressure phase diagram that the experimentally observed phase of BiFeO₃ under the hydrostatic pressure from 3 GPa to 10 GPa is a PbZrO₃-like antiferroelectric phase.

Comparison Of Lock-In And Pulse-Phase Thermography For Defect Characterization In Frp Composites Applied To Concrete, Jeff Brown, Sai Harsha Chittineni

Publications

Thermal imaging is a well-established technique for the non-destructive evaluation of FRP composites applied to reinforced concrete. Defect characterization using IR thermography, however, remains a topic of on-going research, and there are currently no universally accepted standards for data collection or interpretation. This research involved large scale thermography inspection of two FRP strengthened bridge girders that were removed from service after approximately 10 years of service in a potentially corrosive marine environment. Trial inspections were performed on test areas where defects could be identified using sounding methods. Two procedures showed the most promise for identifying and characterizing defects: sinusoidal (lock-in …

Angiogenic Effect Of Bioactive Borate Glass Microfibers And Beads In The Hairless Mouse, Richard J. Watters, Roger F. Brown, D. E. Day

Biological Sciences Faculty Research & Creative Works

The purpose of this project was to investigate the angiogenic mechanism of bioactive borate glass for soft tissue repair in a 'hairless' SKH1 mouse model. Subcutaneous microvascular responses to bioactive glass microfibers (45S5, 13-93B3, and 13-93B3Cu) and bioactive glass beads (13-93, 13-93B3, and 13-93B3Cu) were assessed via: noninvasive imaging of skin microvasculature; histomorphometry of microvascular densities; and quantitative PCR measurements of mRNA expression of VEGF and FGF-2 cytokines. Live imaging via dorsal skin windows showed the formation at two weeks of a halo-like structure infused with microvessels surrounding implanted borate-based 13-93B3 and 13-93B3Cu glass beads, a response not observed with …

Designed Synthesis Of Nanoporous Organic Polymers For Selective Gas Uptake And Catalytic Applications, Pezhman Arab

Theses and Dissertations

Design and synthesis of porous organic polymers have attracted considerable attentions during the past decade due to their wide range of applications in gas storage, gas separation, energy conversion, and catalysis. Porous organic polymers can be pre-synthetically and post-synthetically functionalized with a wide variety of functionalities for desirable applications. Along these pursuits, we introduced new synthetic strategies for preparation of porous organic polymers for selective CO₂ capture.

Porous azo-linked polymers (ALPs) were synthesized by an oxidative reaction of amine-based monomers using copper(I) as a catalyst which leads to azo-linkage formation. ALPs exhibit high surface areas of up to 1200 …

Biological Materials: Part A. Temperature-Responsive Polymers And Drug Delivery And Part B. Polymer Modification Of Fish Scale And Their Nano-Mechanical Properties, Xu Xiang

Dissertations, Master's Theses and Master's Reports - Open

This research has three parts. Two parts deal with novel nanoparticle assemblies for drug delivery, and are described in Part A, while the third part looks at properties of fish scales, an abundant and little-used waste resource, that can be modified to have value in medical and other areas.

Part A describes fundamental research into the affects of block sequence of amphiphilic block copolymers prepared from on a new and versatile class of monomers, oligo(ethylene glycol) methyl ether acrylate (OEGA) and the more hydrophobic di(ethylene glycol) methyl ether methacrylate (DEGMA). Polymers from these monomers are biologically safe and give polymers …

Measurements Of Rf Properties Of Thin Film Nb3Sn Superconducting Multilayers Using A Calorimetric Technique, S. Sosa-Guitron, A. Gurevich, J. Delayen, E. Chang Beom, C. Sundahl, G. V. Eremeev

Physics Faculty Publications

Results of RF tests of NB₃SN thin film samples related to the superconducting multilayer coating development are presented. We have investigated thin film samples of Nb₃Sn/Al₂O₃/Nb with Nb₃Sn layer thicknesses of 50 nm and 100 nm using a Surface Impedance Characterization system. These samples were measured in the temperature range 4 K-19 K, where significant screening by Nb₃Sn layers was observed below 16-17 K, consistent with the bulk critical temperature of Nb₃Sn.

Laser Surface And Sub-Surface Repair During Metal Additive Manufacturing, Prudvi Teja Ravi

Masters Theses

"This study examines the use of laser surface treatment to repair surface and subsurface defects. Numerical analysis was performed on laser surface melting using Gaussian heat distribution equations to analyze the depth of the melt pool created by the phenomena. Concurrently, a process map was developed with a planned set of experiments by varying the ranges of laser power and travel speed to determine the dimensions of the melt pool across the gamut. The data generated from both the process studies and the numerical analysis was then used to determine the ideal operating ranges of the process parameters to repair …