Engineering Science and Materials Commons^™

Self-Biased Circulators For High Power Applications, Alexander S. Sokolov

Electrical and Computer Engineering Master's Theses

Self-biased circulators exploit the properties of high anisotropy magnetic field in hexagonal ferrites, thus allowing operation without biasing magnets and a significant size and weight reduction. Although first self-biased circulators were demonstrated more than 20 years ago, all the prototypes constructed so far are unsuitable for practical applications.

An attempt to design a self-biased circulator from scratch was made. Novel exceptionally low dielectric loss and high heat conductivity ceramic materials were developed and innovative substrate synthesis techniques were employed. Low temperature cofiring of green body ferrite compacts and dielectric ceramic slurries were mastered, resulting in solid composite substrates.

Original device ...

Designing Meaningful Molecular Dynamics (Md) Simulations: The Lithiation Of Silicon, María Camila Rincon, Alejandro Strachan, Hojin Kim, David Guzman, Mathew Cherukara

The Summer Undergraduate Research Fellowship (SURF) Symposium

Molecular dynamics (MD) is used to understand the properties of materials by following the time evolution of the system and exploring the interactions between its constituent atoms. MD simulation allows making reliable predictions of various properties of materials; however, designing useful computer experiments is a complex task that requires the appropriate selection of interatomic interactions (force fields) and other conditions. In this work we discuss some aspects of molecular dynamics that would help the inexperienced users design reliable simulations. The simulation of the lithiation process of silicon is taken as an example for better understanding.

Compression Testing And Failure Modes Of Steel-Concrete Composite (Sc) Structures For Nuclear Containment, Patrick Michael Wanamaker, Amit H. Varma

The Summer Undergraduate Research Fellowship (SURF) Symposium

Although being able to provide much cleaner power than burning coal and other fossil fuels, nuclear power plants are still a tough sell to the general public due to their history of being spontaneously dangerous. The containment structures surrounding these nuclear plants, however, can play a huge role in reducing the risks associated with them. Relatively new designs for these containment assemblies, known as SC (steel-concrete composite) structures, aim to increase the strength and durability of the containment facilities while keeping costs down. By varying the spacing between shear studs, the ratio of concrete to steel, and the ratio of ...

Code Optimization For Phase Field Method, Sergio Andres Monsalve, Marisol Koslowski

The Summer Undergraduate Research Fellowship (SURF) Symposium

The Phase field model method for studying grain dislocation at atomic level after applying an external force to the materials being tested, enables simulate the behavior of different materials after applying stress. With the appropriate numerical method the simulation could change drastically the complexity of the algorithm. Finding the most accurate and stable numerical method for the phase field model give us a considerable improving in the performance of the code used to simulate the phase field dynamic dislocation in larger and more complex simulations can be performed. We made an statistic comparison between the different methods, comparing stability and ...

Modelling Microstructural Evolution In Materials Science, Nana Ofori-Opoku

Open Access Dissertations and Theses

Continuum atomistic and mesoscopic models are developed and utilized in the context of studying microstructural evolution and phase selection in materials systems. Numerous phenomena are examined, ranging from defect-solute interaction in solid state systems to microstructural evolution under external driving conditions. Emphasis is placed on the derivation and development of models capable of self consistently describing the intricate mechanisms at work in the systems undergoing these phenomena.

Namely, grain growth dynamics are studied in nanocrystalline systems under external driving conditions using a newly developed phase-field-crystal model, which couples an additional free energy source term to the standard phase-field-crystal model. Such ...

The Role Of Mechanically Induced Erk Phosphorylation In Stem Cell Adipogenesis, Daniel E. Menter

Engineering Mechanics Dissertations & Theses

Mechanical cell stimulation has only recently been highlighted for its ability to direct cell function and fate. The development of techniques to apply controlled mechanical stimulation to cells has allowed researchers to examine the effects of forces on cell behavior. These studies have shown that cells, and in particular, stem cells are very sensitive to mechanical stimuli. While the potential impact of mechanical forces has been demonstrated by these studies, there have not been many studies that compare the differing effects of stimulation profiles and methods. Further, molecular mechanosensing mechanisms have not been identified. In this work, we compared the ...

Pan Nanofibers And Nanofiber Reinforced Composites, Cheng Ren

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

Nanomaterials play an important role in the development of nanotechnology. They possess unique mechanical, physical, and chemical properties coupled with small size and ultrahigh surface area that can provide critical advantages for applications. Continuous nanofibers attract special interest due to their dual nano-macro nature and ability to bridge scales. Nanofibers are being considered for a broad range of applications spanning advanced filters, separation membranes, ultrasensitive sensors, micro/nano actuators, nanoprobes, tissue engineering scaffolds, protective and smart closing, and multifunctional composites. Most of these applications require certain mechanical properties and robustness. However, the literature on the mechanical behavior of nanofibers and ...

The Equi-Biaxial Fatigue Characteristics Of Epdm Under True (Cauchy) Stress Control Conditions, Mark Johnson, Ray Ekins, Niall Murphy, Steven Jerrams, John Hanley

Conference Papers

ABSTRACT: Strain amplitude control is most often employed when carrying out fatigue testing of rubber components. Often the design engineer requires fatigue test data that is based on load amplitude control. This is analogous to engineering or nominal stress amplitude control. This usually makes it easy to maintain the load within the specified test limits during extended testing. Values of true stress and strain can be obtained from this approach, but the magnitudes of the maximum true stresses in these tests increase with accumulated cycles, whereas the equivalent maximum engineering stress values remain constant. This is easily demonstrated in the ...

Low Velocity Impact Tower Feasibility, Setup, And Impact Testing Of Carbon Fiber Reinforced Epoxy Thermoset And Peek Thermoplastic Matrix Composites, Brent Plehn

Materials Engineering

A low velocity impact tower was donated to Cal Poly's Materials Engineering Department along with four fiber reinforced polymer matrix composites. The tower was set up in building 192 in the Mechanical Testing Laboratory. Improvements were made to the tower including adding velocity detection capabilities, making loose hardware inclusive, adding an extra tower arm for better consistency, adding a double jawed clamp for faster testing, and rerouting the tower's compressed air system to improve performance. A standard operating procedure was drafted, tested, and redrafted for impact testing composite panels. The four composite panels consisted of two quasi-isotropic 16 ...

Beach Wheelchair Project, Rory Aronson, Joshua Marcum, Samuel Coyne, Alex Hayes, Alexa Colburn, Max Hessel, Benedikt Strauss, Marvin Rimmele, Marco Pietsch

Mechanical Engineering

The Beach Wheelchair, Sandcrawler, is a machine intended to help give people with disabilities the full beach experience. The non-profit organization Bridge II Sports sponsored this project, and tasked us with developing the design and fabricating a prototype. This chair has several features including a linkage mechanism that raises and lowers a chair relative to an external frame, hand crank drive with Gates Carbondrive belt and sprockets, buoyant Wheeleez balloon tires, and much more.

Sci-Tech Book News Reviews, Susan Fingerman

Sci-Tech News

No abstract provided.

The Effects Of A Collaborative Problem-Based Learning Experience On Students’ Motivation In Engineering Capstone Courses, Brett D. Jones, Cory M. Epler, Parastou Mokri, Lauren H. Bryant, Marie C. Paretti

Interdisciplinary Journal of Problem-based Learning

We identified and examined how the instructional elements of problem-based learning capstone engineering courses affected students’ motivation to engage in the courses. We employed a two-phase, sequential, explanatory, mixed methods research design. For the quantitative phase, 47 undergraduate students at a large public university completed a questionnaire that measured the components of the MUSIC Model of Academic Motivation (Jones, 2009): empowerment, usefulness, success, situational interest, individual interest, academic caring, and personal caring. For the qualitative phase that followed, 10 students answered questions related to the MUSIC components. We identified several instructional elements that led to motivating opportunities that affected students ...

College Of Engineering Senior Design Competition Spring 2013, University Of Nevada, Las Vegas

Senior Projects (COE)

Senior Design Experience

Part of every UNLV engineering student's academic experience, the Senior Design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs and prototypes a product in this required element of the curriculum. Working in teams, the senior design project encourages students to use everything learned in the engineering and computer design programs to create a practical, real world solution to an engineering challenge.

Beyond the classroom ...

Because of the requirement to work in teams, students also build good communication skills, presentation skills and even business writing skills. They also have to ...

Energy, U.S. Department Of, Bert Chapman

Libraries Faculty and Staff Scholarship and Research

Provides information about the U.S. Department of Energy (DOE) and its predecessor agencies and how DOE influences federal energy policy and scientific research in the western U.S.

Plastic Deformation Of Astm A36 Steel Using Two-Stage Light Gas Gun, Shawoon Kumar Roy

College of Engineering: Graduate Celebration

To characterize material deformation in high velocity impact. To validate material models for computation simulation purposes.

This ongoing research is an attempt to study the plastic deformation of A36 steel plate (0.5” thick) under hypervelocity impact. Plastic deformation of the target plate was simulated using finite element software LS-DYNA.

Numerical Characterization Of The Hydrodynamics And Thermal Behavior Of Air Flow In A "Flex-Duct" Air Distribution System, Samad Gharehdaghi, Samir Moujaes

College of Engineering: Graduate Celebration

The aim of this research paper is to compute the hydrodynamic and heat transfer characteristics of the air flow inside a flexible duct used for residential/small commercial buildings. Various new information which manufacturers do not provide usually are produced numerically among which heat transfer coefficient, needed for estimating heat loss, is a principal one. Circulation zones in depressions are found to exist. It is shown that these regions act as an insulator and decrease the heat loss along the duct. The results show that fully developed conditions exist much earlier with regard to the inlet for both hydrodynamic and ...

Analysis Of Bolted Joints Under Medium And High Impact Loading, Deepak Sankar Somasundaram, Mohamed Trabia, Brendan Otoole

College of Engineering: Graduate Celebration

• Develop test fixture for medium impact study on bolted joints
• Create FEA model that can replicate the experiment
• Develop test fixture for high impact loading
• Create FEA model and select material properties that can produce results that
  closely match experiments.
• Compare different modeling techniques for high impact loading

Single Crystal Silicon Substrate Prepared By Vapour-Liquid Interface Growth, Hao-Ling Yu

Open Access Dissertations and Theses

Preparing silicon wafers is a tedious multi-step process that includes etching, polishing, and cleaning. The minimum wafer thickness attainable in current high volume wafer production processes is generally 160 to 300 μm, and the kerf loss for these processes is up to 40% of the total volume. Thin silicon wafers (~30 to 100μm) are very expensive to produce and the wafering process is not cost effective due to the high amount of material loss (more than 80% at these dimensions) during the process and the risk of breakage of the wafers during wafering. In this thesis, a new method called ...

Mechanics Of Blast Loading On Post-Mortem Human And Surrogate Heads In The Study Of Traumatic Brain Injury (Tbi) Using Experimental And Computational Approaches, Shailesh Govind Ganpule

Engineering Mechanics Dissertations & Theses

Blast induced neurotrauma (BINT) has been designated as the “signature injury” to warfighters in the recent military conflicts. The occurrence of traumatic brain injury (TBI) in blasts is controversial in the medical and scientific communities because the manifesting symptoms occur without visible injuries. Whether the primary blast waves alone can cause mechanical insult that is comparable to existing traumatic brain injury thresholds is still an open question, and this work is aimed to address this issue.

In the first part of this dissertation, mechanics of primary blast loading on Realistic Explosive Dummy (RED) head with and without helmets is studied ...

High-Stress Shear-Induced Crystallization In Isotactic Polypropylene And Propylene/Ethylene Random Copolymers, Zhe Ma, Lucia Fernandez-Ballester, Dario Cavallo, Tim Gough, Gerrit W. M. Peters

Mechanical & Materials Engineering Faculty Publications

Crystallization of an isotactic polypropylene (iPP) homopolymer and two propylene/ethylene random copolymers (RACO), induced by high-stress shear, was studied using in situ synchrotron wide-angle X-ray diffraction (WAXD) at 137 °C. The “depth sectioning” method (Fernandez-Ballester, Journal of Rheology 53:5 (2009), pp. 1229−1254) was applied in order to isolate the contributions of different layers in the stress gradient direction and to relate specific structural evolution to the corresponding local stress. This approach gives quantitative results in terms of the specific length of fibrillar nuclei as a function of the applied stress. As expected, crystallization becomes faster with increasing ...