Physics Commons^™

One-Dimensional Weakly Nonlinear Model Equations For Rossby Waves, David Henry, Rossen Ivanov

Articles

In this study we explore several possibilities for modelling weakly nonlinear Rossby waves in fluid of constant depth, which propagate predominantly in one direction. The model equations obtained include the BBM equation, as well as the integrable KdV and Degasperis-Procesi equations.

Electronic & Magnetic Properties Of Ba(Fe,Co)2as2 & Uru2si2, Travis J. Williams

Open Access Dissertations and Theses

This thesis details a collection of experiments performed on two condensed matter systems, Co-doped BaFe₂As₂ and URu₂Si₂. These two materials are related by their structural type (ThCr₂Si₂-type) serving as great examples of the diversity of material properties present in this family. They are also both superconducting materials and belong to the collection of strongly-correlated electron systems. The interest in studying the Ba(Fe,Co)₂As₂ group of materials is due to the high superconducting transition temperature in these (and related) materials, while the compound URu₂Si_{2 ...}

Phase Field Crystal Studies Of Strain-Mediated Effects In The Thermodynamics And Kinetics Of Interfaces, Jonathan F E Stolle

Open Access Dissertations and Theses

In this dissertation, the Phase Field Crystal (PFC) Method is used to study a number of problems in which interfaces and elastic effects play important roles in alloys. In particular, the three topics covered in this work are grain boundary thermodynamics in alloys, dislocation-mediated formation of clusters in binary and ternary alloys, and solutal effects in explosive crystallization. Physical phenomena associated with grain boundaries, such as Read-Shockley-like behaviour and Gibbs adsorp- tion theorem, were shown to be accurately captured in both PFC- and XPFC-type models. In fact, a connection between the solute segregation behaviour and physical properties of the system ...

Neutron Scattering Studies Of Magnetic Oxides Based On Triangular Motifs, Katharina Fritsch

Open Access Dissertations and Theses

The following dissertation presents neutron scattering studies on three specific magnetic insulating oxide materials whose lattice is based on triangular structural motifs. Each of the three materials studied, LuCoGaO₄, Co₃V₂O₈ and Tb₂Ti₂O₇, displays an interesting disordered ground state that is reached by different mechanisms: site disorder, geometric frustration, and quantum fluctuations induced by a transverse magnetic field. The main focus of this work is the characterization of the resulting magnetic ground states and magnetic excitations within these systems.

Chapters 3, 4 and 5 contain original work in the form ...

Development Of A Thgem Imaging Detector With Delay Line Readout, Andrei Hanu

Open Access Dissertations and Theses

Position sensitive detectors represent a class of particle detectors widely used in high-energy physics, astrophysics, biophysics and medicine for imaging the spatial distribution of various radioactive sources. In recent years, a new class of gas based detectors, so-called micropattern gas detectors (MPGDs), has emerged. While modern MPGDs rival solid state detectors in terms of spatial and temporal resolution, their cost of production is significantly lower. A Thick Gaseous Electron Multiplier (THGEM) imaging detector, with a two-dimensional delay line readout, has been constructed as a concept for a large area imaging detector with reasonable spatial resolution. The delay line based THGEM ...

Resonant Curved Piezoelectric Cantilever Fluid Diode Wings For Mass-Producible Flying Microrobots, Matthew D. Minnick

Open Access Dissertations and Theses

This work explores a new method of force generation for flying robots on the sub-cm wingspan scale: resonant curved piezoelectric cantilevers created using completely parallel MEMS fabrication. It theorizes that because a resonating curved beam has a different drag coefficient on the upstroke than the downstroke, it should act as a fluid diode: a partial one-way gate for fluids, and thereby generate an asymmetric force over a symmetric one-degree-of-freedom flapping cycle. It develops a simplified model for the large-amplitude resonant mode of thin circular arcs by analytically extending the resonant mode shape of straight cantilevers, shows that this shape is ...

Capture Of Magnetic Inelastic Dark Matter In The Sun, Matthew Mccreadie

Open Access Dissertations and Theses

We consider the phenomenology of the Magnetic Inelastic Dark Matter model, specifically its capture and subsequent annihilation in the Sun. By using the most recent data from the IceCube and Super- Kamiokande neutrino detection experiments, we are able to put limits on the dipole moment of this WIMP candidate for masses ranging from 100 GeV to 10 TeV with a mass-splitting ranging from 0 to 200 keV. Limits are placed on a 100 GeV WIMP with magnetic dipole interactions as low as 2.6 × 10^−6µN for an inelastic parameter of 100 keV

Turbulence, Climate And Supercomputers, Georgios Matheou

The STEAM Journal

Turbulence is often referred to as the last mystery of classical physics. Although turbulence is ubiquitous and prominent in our daily lives – from the mixing of milk in a cup of coffee to the perpetual motion of the atmosphere and the resulting weather variation – our understanding of this complex phenomenon is comparatively very limited (e.g., Davidson et al., 2011).

In-Package Atmospheric Pressure Cold Plasma Treatment Of Strawberries, N. N. Misra, Paula Bourke, Patrick J. Cullen, Sonal Patil

Articles

The ability to generate low temperature plasma at atmospheric pressure offers new opportunities to decontaminate biological materials, including fresh foods. In this study, strawberries were treated with atmospheric cold plasma (ACP), generated with a 60 kV dielectric barrier discharge (DBD) pulsed at 50 Hz, across a 40 mm electrode gap, generated inside a sealed package containing ambient air (42% relative humidity). The current-voltage characteristics revealed that the plasma operated in the filamentary regime. The background microflora (aerobic mesophillic bacteria, yeast and mould) of strawberries treated for 5 min was reduced by 2 log 10 within 24 h of post-ACP treatment ...

Creating 'Reflection And Refraction', Tara Prescott

The STEAM Journal

This essay offers personal narrative about the creation of Reflecting and Refracting, a collage artwork integrating literary and scientific texts regarding light. Reflecting and Refracting was made specifically for the STEAM journal’s first issue and elements were incorporated into the issue’s collaborative cover image, Equations of Light. The current essay, however, is the first time the original artwork is being published in its entirety.

Spannungsfeld, Julian Voss-Andreae

The STEAM Journal

My design for a sculptural installation for the University of Minnesota’s new Physics and Nanotechnology Building is inspired by a view of the human body through the lens of quantum physics.

The German title of the installation (literally "tension field") originated in physics but is used in contemporary German almost exclusively in a metaphorical sense, implying a dynamic tension, often between polar opposites, that permeates everything in its vicinity.

Session D-4: Teaching Quantum Mechanics, Peter Dong

Professional Learning Day

Quantum mechanics is a part of modern life, playing a major role in chemistry, computing, nanotechnology, cryptography, and even biology. Many students are fascinated by the principles of quantum mechanics - and wave-particle duality is now in the Next Generation Science Standards. This course will present a basic introduction to quantum mechanics, accessible to middle or high school students, that will give students a taste of how strange and wonderful the universe really is (while also meeting the new standard). Teachers will be given slides and materials so they can teach the lesson themselves.

I. Accurate 50-200 Kev Proton Stopping Cross Sections In Solids Ii. Lateral Growth Of Si Wires On Si (100) Substrate, Sergey Dedyulin

University of Western Ontario - Electronic Thesis and Dissertation Repository

Medium energy ion scattering (MEIS) is used to determine the elemental depth profile in the first few hundred angstroms of a sample. The interpretation of MEIS spectra requires an accurate knowledge of the rate at which the ions lose their energy - the stopping cross section, ε. The rate of energy loss has been fairly well investigated, both experimentally and theoretically, in elemental and compound targets at high energies (E>400 keV/amu). However, in the medium ion energy range where stopping cross section typically has a maximum, experimental data are scarce while most of the existing theories fail to give ...

Using Acrylamide Based Photopolymers For Fabrication Of Holographic Optical Elements In Solar Energy Applications, Hoda Akbari, Izabela Naydenova, Suzanne Martin

Articles

A holographic device is under development that aims to improve light collection in solar cells. The aim is to explore the potential of using photopolymer Holographic Optical Elements (HOE) to collect light from a moving source, such as the sun, and re-direct it for concentration by a holographic lens.. A working range of 45 degrees is targeted for such a device to be useful in solar applications without tracking. A photopolymer HOE is capable of efficiently re-directing light, but the angular selectivity of a single grating is usually of the order of one degree at the thicknesses required for high ...

Battery Free Wireless Sensor Networks: Theory And Applications, Ali Abedi

WiSe-Net Laboratory

One of the major hurdles in wide spread use of wireless sensor networks is power consumption, i.e., the battery limitations. For several years, researchers tried to minimize power consumption of wireless nodes by designing more efficient data collection, transmission, storage, and processing methods. In this position paper, we will review the paradigm changing battery-free wireless sensing, which was originally designed for monitoring NASA’s inflatable lunar habitat and ended up being commercialized for monitoring jet engines, brain injury detection, and indoor navigation. Theory and practical applications presented in this paper will cover basic research in a University lab to ...

In-Package Nonthermal Plasma Degradation Of Pesticides On Fresh Produce, N. N. Misra, Shashi Kishor Pankaj, Tony Walsh, Finbarr O'Regan, Paula Bourke, Pj Cullen

Articles

In-package nonthermal plasma (NTP) technology is a novel technology for the decontamination of foods and biological materials. This study presents the first report on the potential of the technology for the degradation of pesticide residues. A cocktail of pesticides, namely Azoxystrobin, Cyprodinil, Fludioxonil and Pyriproxyfen was tested on strawberries. The concentrations of these pesticides were monitored in priori and post- plasma treatment using GC-MS/MS. An applied voltage and time dependent degradation of the pesticides was observed for treatment voltages of 60, 70 and 80 kV and treatment durations ranging from 1 to 5 min, followed by 24 h in-pack ...

The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre

Charles G. Torre

We give a set of local geometric conditions on a spacetime metric which are necessary and sufficient for it to be a null electrovacuum, that is, the metric is part of a solution to the Einstein-Maxwell equations with a null electromagnetic field. These conditions are restrictions on a null congruence canonically constructed from the spacetime metric, and can involve up to five derivatives of the metric. The null electrovacuum conditions are counterparts of the Rainich conditions, which geometrically characterize non-null electrovacua. Given a spacetime satisfying the conditions for a null electrovacuum, a straightforward procedure builds the null electromagnetic field from ...

Deposition And Analysis Of Copper Indium Disulfide For Photovoltaic Applications, Frederick Wade

Macalester Journal of Physics and Astronomy

Thin Film semiconductors were created through the methods of electrochemistry to produce a copper, indium and sulfur metal alloy that could be placed on a stainless steel substrate. We observed other properties regarding the relative indium to copper relationships and both the macro and micro structure of the final product. X-­‐ray diffraction, SEM imaging, and atomic absorption spectroscopy data suggest a relatively intact metal alloy, but also an inaccurate ratio of indium to copper.

Photometric And Spectroscopic Analysis Of Young, Nearby Open Cluster Collinder 70, Clara M. Thomann

Macalester Journal of Physics and Astronomy

We present the results of a wide-field (80’ x 80’) photometric and spectroscopic survey of the young open cluster Collinder 70, which is also known as the ORI OB 1b association, centered on the central star of Orion’s belt, ε Ori (Alnilam). Seventy Coll 70 spectroscopy targets were selected from BVRIc color magnitude diagrams for observation using the CTIO HYDRA multi-object spectrograph; we aimed to identify targets exhibiting H" in emission and a strong lithium 6708Å line in absorption. About a third of our targets (23/70 stars) are consistent with being youthful members of Coll 70. Intermediate resolution ...

Monte Carlo Simulation For Silicon On Silane Hwcvd For Thin Film Solar Cells, Annaleigh Smith

Macalester Journal of Physics and Astronomy

Thin film solar cells offer a viable alternative to crystal silicon solar cells. They are expected to be cheaper to fabricate because they use material more efficiently, and are deposited in a process which can create larger area solar cells [1]. However, a high deposition rate is necessary for economic viability. A Monte Carlo simulation can model the molecular interactions in hot wire chemical vapor deposition and track the position and velocity distribution of molecular species in the gas [2]. Determining the flux on the substrate can help us to increase deposition rate by adjusting control parameters accordingly [3]. As ...