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Full-Text Articles in Physics

Robust And Economical Autonomous Navigation Via Advanced Bayesian Methods, Ali H. Chaudry May 2012

Robust And Economical Autonomous Navigation Via Advanced Bayesian Methods, Ali H. Chaudry

Physics

A 2009 NASA SBIR grant awarded to Autonomous Exploration, Inc., was partially used to fund students at the University at Albany to help research whether autonomous navigation systems can be prepared at a much lower cost than is currently being done. Expensive and bulky sensors (the basis of current-generation navigation systems) can be avoided by using commercially available low-cost sensors; the disadvantages of these low-cost sensors can be eluded by using novel data-processing techniques such as Bayesian analysis. Integration of these methods can lead to low-cost navigation systems, and hence, rovers. Potential applications include extra-planetary surface exploration as well as …


Techniques For Improving Parameter Estimation In Esr, Troy R. Broderick May 2012

Techniques For Improving Parameter Estimation In Esr, Troy R. Broderick

Physics

This paper is to address the need for better estimates of the ESR spectral parameters of biological systems. In this paper I focus on models of spectral lineshapes and will be applying these techniques to more complicated lineshapes. Multifrequency ESR is a powerful technique for identifying and characterizing dynamic modes in natively unfolded biopolymers in general and loop regions in particular. I will introduce the reader to properties of ESR, formalisms and common techniques in the field. A common result for a simple ESR line is a Lorentzian distribution that is characterized by a mode and width. Information about the …


Modeling Of Megavoltage And Low Energy Focused X-Ray Beams Using Mcnp5, Hassan Abbas Jan 2012

Modeling Of Megavoltage And Low Energy Focused X-Ray Beams Using Mcnp5, Hassan Abbas

Legacy Theses & Dissertations (2009 - 2024)

In this thesis 6 and 18 MV photon beams for a Varian linear accelerator were simulated using a general purpose Monte Carlo code MCNP5 (Monte Carlo N-Particle Transport Code). The potential of MCNP5 is explored to calculate the dose in high dose gradient regions. In addition, MCNP5 was used to model another geometry, low energy focused x ray beams created with polycapillary optics, to explore their potential to provide a different skin-sparing technique for radiation therapy.


Information Theory Applied To Parameter Inference Of The Nuclear Resonance Absorption Lineshape Of A Hydrated Crystal, Kiel A. Hock Jan 2012

Information Theory Applied To Parameter Inference Of The Nuclear Resonance Absorption Lineshape Of A Hydrated Crystal, Kiel A. Hock

Legacy Theses & Dissertations (2009 - 2024)

Magnetic resonance absorption lineshapes can be difficult to calculate but there are simple model systems for which analytical expressions are available which makes model exploration much easier. One goal of this work is to quantify how well model parameters may be inferred from a signal using tools from information theory. Another goal is to equip ourselves with tools to assess the importance of missing parameters in our model. We do this by monitoring the partition function determined from a suitably defined probability mass function for various parameter values. The optimum parameter set makes the partition function a maximum which gives …


Conformal Field Theory And Its Application To The Ising Model, Joshua Edward Meyer Jan 2012

Conformal Field Theory And Its Application To The Ising Model, Joshua Edward Meyer

Legacy Theses & Dissertations (2009 - 2024)

The two-dimensional Ising model was originally solved by Onsager using statistical physics techniques. More recently, it has been found that the derivation of critical exponents and correlation functions can be greatly simplified by using the methods of Conformal Field Theory (CFT). We review these methods and apply them to the two-dimensional Ising model. The connection between the continuum limit Ising model and the field theory of free fermions is explained, resulting in a CFT on the plane with two non-trivial fields. Through the use of bosonization on the plane, the free-field correlation functions of the model are computed.


The Influence Of Copper Substrate Orientation On Graphene Growth, Zachary Robert Robinson Jan 2012

The Influence Of Copper Substrate Orientation On Graphene Growth, Zachary Robert Robinson

Legacy Theses & Dissertations (2009 - 2024)

This dissertation is focused on determining the influence of the copper substrate on graphene grown by \ac{CVD}. Graphene, which can be grown in single atomic layers on copper substrates, has potential applications in future electronic devices. One of the key issues for the use of graphene grown by chemical vapor deposition for device applications is the influence of defects on the transport properties of the graphene. For instance, growth on metal foil substrates results in multi-domain graphene growth because the foil substrates themselves have a variety of different surface terminations. Therefore, they don't serve as a very good template for …


Experimental And Theoretical Analysis Of Strain Engineered Aluminium Nitride On Silicon For High Quality Aluminium(X)Indium(Y)Gallium(1-X-Y)Nitride Epitaxy, Mihir Hemant Tungare Jan 2012

Experimental And Theoretical Analysis Of Strain Engineered Aluminium Nitride On Silicon For High Quality Aluminium(X)Indium(Y)Gallium(1-X-Y)Nitride Epitaxy, Mihir Hemant Tungare

Legacy Theses & Dissertations (2009 - 2024)

III-Nitrides on Si are of great technological importance due to the availability of large area, epi ready Si substrates and the ability to heterointegrate with mature silicon micro and nanoelectronics. The major roadblock with realizing this is the large difference in thermal expansion coefficients and lattice constants between the two material systems. A novel technique developed in our research lab shows the potential of simultaneous and substantial reduction in dislocation and crack density in GaN on Si (111). Research undertaken in the current doctoral dissertation, validates the superior GaN quality on Si obtained using our technique and determines the factors …