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Full-Text Articles in Physics

Genetic Algorithm Design Of Photonic Crystals For Energy-Efficient Ultrafast Laser Transmitters, Troy A. Hutchins-Delgado Nov 2018

Genetic Algorithm Design Of Photonic Crystals For Energy-Efficient Ultrafast Laser Transmitters, Troy A. Hutchins-Delgado

Shared Knowledge Conference

Photonic crystals allow light to be controlled and manipulated such that novel photonic devices can be created. We are interested in using photonic crystals to increase the energy efficiency of our semiconductor whistle-geometry ring lasers. A photonic crystal will enable us to reduce the ring size, while maintaining confinement, thereby reducing its operating power. Photonic crystals can also exhibit slow light that will increase the interaction with the material. This will increase the gain, and therefore, lower the threshold for lasing to occur. Designing a photonic crystal for a particular application can be a challenge due to its number of ...


The Relationship Between Electrical Conductivity And Magnetically Damped Motion, Kalem Akhtar Jun 2018

The Relationship Between Electrical Conductivity And Magnetically Damped Motion, Kalem Akhtar

The International Student Science Fair 2018

Varying electrical conductivities of different, non-magnetic metals appears to affect the magnitude of magnetically damped motion. To determine the relationship between magnetic damping and conductivity an experiment was designed using different length tubes of aluminium, copper and brass. The tubes had the same diameter and similar wall thickness. A short, cylindrical neodymium magnet was dropped through the tubes of and the time for the magnet to traverse the tube was recorded using a smartphone camera. These times allowed for the terminal velocity to be calculated for each metal length and the average terminal velocity for each metal was determined. This ...


Thermoelectric Magnetohydrodynamic Effects In Solidification Processes, Andrew Kao, Koulis Pericleous, Peter Lee, Biao Cai, Jianrong Gao Oct 2016

Thermoelectric Magnetohydrodynamic Effects In Solidification Processes, Andrew Kao, Koulis Pericleous, Peter Lee, Biao Cai, Jianrong Gao

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


Photonicstd-2d: Modeling Light Scattering In Periodic Multilayer Photonic Structures, Alexey Bondarev, Shaimaa Azzam, Zhaxylyk Kudyshev, Alexander V. Kildishev Aug 2016

Photonicstd-2d: Modeling Light Scattering In Periodic Multilayer Photonic Structures, Alexey Bondarev, Shaimaa Azzam, Zhaxylyk Kudyshev, Alexander V. Kildishev

The Summer Undergraduate Research Fellowship (SURF) Symposium

Efficient modeling of electromagnetic processes in optical and plasmonic metamaterials is important for enabling new and exciting ways to manipulate light for advanced applications. In this work, we put together a tool for numerical simulation of propagation of normally incident light through a nanostructured multilayer composite material. The user builds a unit cell of a given material layer-by-layer starting from a substrate up to a superstrate, splitting each layer further into segments. The segments are defined by width and material -- dielectric, metal or active medium. Simulations are performed with the finite difference time domain (FDTD) method. A database of common ...


Triad Computing, Madison Hanberry Apr 2016

Triad Computing, Madison Hanberry

Georgia State Undergraduate Research Conference

No abstract provided.


Calibration Of Air-Coupled Transducers For Absolute Nonlinear Ultrasonic Measurements, Nicholas Selby, David Torello, Jin-Yeon Kim, Laurence J. Jacobs Jan 2016

Calibration Of Air-Coupled Transducers For Absolute Nonlinear Ultrasonic Measurements, Nicholas Selby, David Torello, Jin-Yeon Kim, Laurence J. Jacobs

Review of Progress in Quantitative Nondestructive Evaluation

We describe a novel calibration technique of air-coupled transducers for nonlinear ultrasonic measurements through homogenous, isotropic media. Our calibration technique combines laser interferometrywith a model-based approach to derive a relationship between received force at the transducer face and the measured output voltage. Conventional nonlinear ultrasonic measurement techniques have relied upon contact receiving transducers that are heavily influenced by contact conditions (e.g. inconsistent coupling) and laser interferometers that are prohibitively expensive and rely on a mirror-finished surface or complicated optics. Air-coupled transducers are significantly less expensive than laser interferometers and are robust relative to surface conditions, but current calibration techniques ...


Electromagnetic Modelling Of An Eddy-Current Position Sensor In For Use In A Fast Reactor, Tao Wu, John Bowler Jan 2016

Electromagnetic Modelling Of An Eddy-Current Position Sensor In For Use In A Fast Reactor, Tao Wu, John Bowler

Review of Progress in Quantitative Nondestructive Evaluation

In this article, we proposed a novel theoretical electromagnetic model of an eddy current probe used as a position sensor with respect to a tube in a fast reactor under standby conditions while immersed in a liquid metal coolant. In these circumstances the coil position cannot be guided by optical aids but electromagnetic sensing can be used. Initially, we derived analytical expressions for the quasi-static time-harmonic electromagnetic field of a circular current filament via the transverse magnetic potential expressed in terms of a single layer potential. This is then used to deduce the field of a circular sensor coil near ...


Pseudo-Pulse-Echo Mode Focused Rayleigh Wave Emats For High Resolution Imaging Of Surface-Breaking Defects, C. B. Thring, Y. Fan, R. S. Edwards Jan 2016

Pseudo-Pulse-Echo Mode Focused Rayleigh Wave Emats For High Resolution Imaging Of Surface-Breaking Defects, C. B. Thring, Y. Fan, R. S. Edwards

Review of Progress in Quantitative Nondestructive Evaluation

Electromagnetic Acoustic Transducers (EMATs) are useful in Non-Destructive Testing as they can be used at lift-off on hot, moving, and rusted surfaces while being relatively inexpensive and robust. Generation of ultrasound using EMATs is relatively inefficient, however, the amplitude of the signal at a defect can be greatly improved with the use of focusing. A focused Rayleigh wave EMAT has been designed, characterized, and used to size a range of surface breaking defects in aluminum. The EMAT has improved spatial resolution compared to unfocused designs and generates a strong signal (giving up to 30 dB SNR) at the focal point ...


Limited View Guided Wave Tomography Based On Full Waveform Inversion, Jing Rao, Madis Ratassepp, Zheng Fan Jan 2016

Limited View Guided Wave Tomography Based On Full Waveform Inversion, Jing Rao, Madis Ratassepp, Zheng Fan

Review of Progress in Quantitative Nondestructive Evaluation

Guided wave tomography offers good potential to estimate the remnant thicknesses of corrosion patches without scanning an ultrasonic transducer along the surface. It uses the dispersion characteristics of guided waves, and reconstructs the thickness map by the inversion of ultrasonic signals captured by a transducer array around the inspection area. A guided wave tomography method based on full waveform inversion (FWI) was developed for the corrosion mapping, which uses a numerical forward model to predict the scattering of guided wave through corrosion defects, and an iterative inverse model to reconstruct the corrosion profile.

In this study, the FWI method is ...


Compton Imaging Tomography For Nondestructive Evaluation Of Spacecraft Thermal Protection Systems, Volodymyr Romanov, Eric Burke, Victor Grubsky Jan 2016

Compton Imaging Tomography For Nondestructive Evaluation Of Spacecraft Thermal Protection Systems, Volodymyr Romanov, Eric Burke, Victor Grubsky

Review of Progress in Quantitative Nondestructive Evaluation

Novel nondestructive evaluation (NDE) systems based on a recently pioneered Compton Imaging Tomography (CIT) technique [1-4] are currently being developed by Physical Optics Corporation (POC). CIT provides high-resolution, three-dimensional, Compton scattered X-ray imaging of the internal structure of evaluated objects, using a set of acquired two-dimensional, Compton scattered X-ray images of consecutive cross sections of these objects. Unlike conventional computerized tomography, CIT requires only one-sided access to objects, has no limitation on the dimensions and geometry of such objects, and can be applied to large, multilayer, nonuniform objects. Also, CIT does not require any contact with objects during its application ...


Experimental Design And Construction For Critical Velocity Measurement In Spin-Orbit Coupled Bose-Einstein Condensates, Ting-Wei Hsu, Yong P. Chen Aug 2015

Experimental Design And Construction For Critical Velocity Measurement In Spin-Orbit Coupled Bose-Einstein Condensates, Ting-Wei Hsu, Yong P. Chen

The Summer Undergraduate Research Fellowship (SURF) Symposium

Quantum simulation using ultra-cold atoms, such as Bose-Einstein Condensates (BECs), offers a very flexible and well controlled environment to simulate physics in different systems. For example, to simulate the effects of spin orbit coupling (SOC) on electrons in solid state systems, we can make a SOC BEC which mimics the behavior of SOC electrons. The goal of this project is to see how the superfluid property of BECs change in the presence of SOC. In particular, we plan to measure the critical velocity of an 87Rb BEC with and without SOC by stirring it with a laser. This laser needs ...


Advances In Pultiple-Pulse Radio-Frequency-Gradient Imaging Of Solids, John Marohn, David N. Shykind, Margat H. Werner, Daniel P. Weitekamp Jan 1993

Advances In Pultiple-Pulse Radio-Frequency-Gradient Imaging Of Solids, John Marohn, David N. Shykind, Margat H. Werner, Daniel P. Weitekamp

Review of Progress in Quantitative Nondestructive Evaluation

Magnetic resonance imaging (MRI) has become the premier tool for the non-destructive evaluation of soft tissue in living systems [1]. Established liquid-state MRI strategies are generally found to be inappropriate for the imaging of rigid solids, because the linewidth for nuclear magnetic resonance in solids is orders-of-magnitude larger than in liquids. Methods currently under development for the NMR imaging of solids either involve the use of very large (fringe-field) magnetic field gradients to encode spatial information over very short periods of time [2], or employ multiple-pulse line-narrowing techniques that prolong a solid’s apparent transverse relaxation time [3–7]. In ...


Progress Towards The Application Of Laser-Ultrasonics In Industry, Jean-Pierre Monchalin Jan 1993

Progress Towards The Application Of Laser-Ultrasonics In Industry, Jean-Pierre Monchalin

Review of Progress in Quantitative Nondestructive Evaluation

Ultrasonic techniques are widely used in industry for thickness gauging, flaw detection and materials characterization. The ultrasonic waves are usually generated and detected by piezoelectric transducers and coupled to the inspected part either by direct contact or through a water bath or a water jet. Although widespread and generally cost effective, these conventional ultrasonic techniques suffer from essentially two severe limitations, which impact upon their use for on-line process control and the inspection of advanced materials.


Reception Of Laser Generated Ultrasound From A Cfrp Plate By An Air Matched Piezoelectric Composite Transducer, L. Scudder, D. A. Hutchins, G. Hayward Jan 1993

Reception Of Laser Generated Ultrasound From A Cfrp Plate By An Air Matched Piezoelectric Composite Transducer, L. Scudder, D. A. Hutchins, G. Hayward

Review of Progress in Quantitative Nondestructive Evaluation

Laser generated ultrasound is being investigated [1,2] for testing structures made of both conventional metals and carbon fibre reinforced polymer (CFRP). Laser interferometers are widely used in such work to detect the normal surface motion caused by ultrasonic pulses. Interferometers offer non-contact, remote and high-fidelity detection, together with a potential to cover large areas rapidly by optical scanning. However their cost is high and only in testing large and/or expensive structures may the cost be justified. A lower cost alternative, but with some compromise on the virtues of an interferometer, would be to use an air transducer as ...


Solid Rocket Motor Nde Using Nuclear Magnetic Resonance, Lowell Burnett, Dale R. Mckay, Erik M. Magnuson, E. J. Vanderheiden Jan 1993

Solid Rocket Motor Nde Using Nuclear Magnetic Resonance, Lowell Burnett, Dale R. Mckay, Erik M. Magnuson, E. J. Vanderheiden

Review of Progress in Quantitative Nondestructive Evaluation

Solid rocket motors (SRMs) are complex integrated structures. An integral part of an SRM is the adhesive liner, which is used to bond the propellant to the insulator covering the inner surface of the case. In order to ensure SRM performance and reliability, the adhesive liner must be properly cured, of the specified thickness, and free of contamination. The goal of this study is to demonstrate the feasibility of a nuclear magnetic resonance (NMR) method to ensure that these conditions are met.


Nuclear Quadrupole Resonance As A Non-Destructive Testing Tool, George Williams, Z. M. Saleh, P. Hari Jan 1993

Nuclear Quadrupole Resonance As A Non-Destructive Testing Tool, George Williams, Z. M. Saleh, P. Hari

Review of Progress in Quantitative Nondestructive Evaluation

Nuclear pure quadrupole resonance (NQR) is a resonance technique that provides distinctly different information from that provided by nuclear magnetic resonance (NMR). In NMR the splitting of the energy levels, and therefore the frequency observed, occurs because of the interaction of the nuclear magnetic moment with an external magnetic field. Information about the system under study comes from perturbations on this magnetic interaction. These perturbations lead to a broadening of the line, or to relaxation effects on the interchange of energy between the spins and the lattice, and among the spins. In NQR the primary interaction is between the electric ...


Accuracy Of The Image Technique For Calculating Electro-Magnetic Field Induced At The Surface Of A Ferromagnetic Metal, S. Sadeghi, D. Mirshekar-Syahkal Jan 1993

Accuracy Of The Image Technique For Calculating Electro-Magnetic Field Induced At The Surface Of A Ferromagnetic Metal, S. Sadeghi, D. Mirshekar-Syahkal

Review of Progress in Quantitative Nondestructive Evaluation

Recently, the surface magnetic field measurement (SMFM) technique for the detection and sizing of surface breaking cracks in ferromagnetic metals was introduced [1–5]. In this technique a rectangular coil or a set of U-shaped wires excited by a high frequency ac current produces the eddy current in the area under inspection. The location, depth and width of a crack in the test area are obtained by interpreting the measurements on a tangential component of the magnetic field at the metal surface using a mathematical modeling. The mathematical modeling assumes that in the absence of crack, the magnetic field at ...


Experiments With Double Microwave Apertures, John Basart, Zhong Zhang Jan 1993

Experiments With Double Microwave Apertures, John Basart, Zhong Zhang

Review of Progress in Quantitative Nondestructive Evaluation

One of the significant characterizations of microwave imaging is the spatial resolution. The relative long wavelength of microwaves as compared to ultrasonic waves and x-rays necessarily means that aperture arrays (real-time or synthetic) are required for high-resolution microwave imaging. Certain limitations on resolution apply regardless of how the array is realized. Types of antenna arrays fall into two broad categories: Phased arrays which are usually operated in real time by scanning a beam past an object, and aperture synthesis in which data are collected with one or more antennas and later processed to produce an image. In NDE we are ...


The Use Of Optical Beam Deflection (Obd) Technique In The Thermal Diffusivity Characterization Of Polymer Foils, J. Rantala, Lanhua Wei, P. K. Kuo, J. Jaarinen, M. Luukkala, R. L. Thomas Jan 1993

The Use Of Optical Beam Deflection (Obd) Technique In The Thermal Diffusivity Characterization Of Polymer Foils, J. Rantala, Lanhua Wei, P. K. Kuo, J. Jaarinen, M. Luukkala, R. L. Thomas

Review of Progress in Quantitative Nondestructive Evaluation

The rapid progress in development of new materials has also created more demands on their testing and characterization methods. In spite of the wide use of different plastics, there is a lack of methods to measure thermal diffusivity of polymers and other low-diffusivity materials. The diffusivity determination of oriented polymers is of particular interest: the drawing of a polymer foil orients the molecular chains, which strengthens the foil mechanically and also causes anisotropy to thermal conductivity making it higher parallel to the drawing direction than perpendicular to it. Anisotropy ratios as high as 100 have been reported [1]. The diffusivity ...


Reluctance Variation As A Result Of Lift Off For An Ac Magnetic Bridge, William F. Schmidt, Otto H. Zinke Jan 1993

Reluctance Variation As A Result Of Lift Off For An Ac Magnetic Bridge, William F. Schmidt, Otto H. Zinke

Review of Progress in Quantitative Nondestructive Evaluation

To optimize the sensitivity and minimize lift-off effects of electromagnetic NDE devices requires an understanding of the source and distribution of electromagnetic fields. This understanding is particularly difficult when conductive devices other than the sample are in the vicinity of the field. Such is the case with the modified AC magnetic bridge [1] which has a conducting insert in the vicinity of the gap in proximity to the sample.


Seeing With Light, Sound, Microwaves, X-Rays, Gamma Rays, Etc., Glen Wade Jan 1990

Seeing With Light, Sound, Microwaves, X-Rays, Gamma Rays, Etc., Glen Wade

Review of Progress in Quantitative Nondestructive Evaluation

It is common to regard humans as being able to see only with light, but about a hundred years ago at the beginning of the modern era, along came x-rays and sonograms. By now technology has made it possible for us to see in a great many different ways. Important views such as underground pools of oil, tumors in the brain, fine structure in the rings of Saturn, ship wreckage on the bottom of the ocean, cracks in the ice packs of the Arctic, all these views and many more, completely unperceivable one hundred years ago, are available to us ...


Eddy-Current Probe Interaction With Subsurface Cracks, John R. Bowler Jan 1987

Eddy-Current Probe Interaction With Subsurface Cracks, John R. Bowler

Review of Progress in Quantitative Nondestructive Evaluation

Electric current will flow around on open crack in a conductor and give rise to very abrupt variations in the field. If the crack has a negligible opening it acts as a surface barrier where the field is virtually discontinuous. Effectively the crack is then equivalent to a layer of current dipoles with the dipole orientation normal to the surface and pointing upstream. An integral equation for the dipole density has been derived for an idealised subsurface crack using the Green’s function method [1]. Numerical solutions have been found by assuming a piecewise constant dipole density and satisfying boundary ...


Optical Range Finder, G. Q. Xiao, D. B. Patterson, G. S. Kino Jan 1987

Optical Range Finder, G. Q. Xiao, D. B. Patterson, G. S. Kino

Review of Progress in Quantitative Nondestructive Evaluation

Recently, a great deal of interest has been shown in making accurate range measurements with good transverse definition. This capability makes it possible, in machine vision systems, to extract geometrical shape information from the images. In robot position sensing, it is important to determine the absolute distance instead of distance change so that noncontinuous measurements can be made without the need for calibration at start-up. A third application of great importance is to measure the shape and size of machined parts with a noncontacting sensor.


The Effect Of Oxygen On The Ion-Acoustic Signal Generation Process, F. G. Satkiewicz, J. C. Murphy, J. W. Maclachlan, L. C. Aamodt Jan 1987

The Effect Of Oxygen On The Ion-Acoustic Signal Generation Process, F. G. Satkiewicz, J. C. Murphy, J. W. Maclachlan, L. C. Aamodt

Review of Progress in Quantitative Nondestructive Evaluation

Thermal wave imaging (TWI) describes a family of methods for materials characterization based on temperature changes induced by an external source. The source can be a laser [1,2,3] or an electron [4,5,6] beam modulated to produce time-varying surface and bulk temperatures in the specimen. Recently, ion sources have been used for excitation [7,8,9] and share some imaging features in common with laser and electron sources. All three types of sources have the ability to detect buried defects in opaque solids and to locate tightly closed cracks [10]. However, the fundamental physical mechanisms of signal ...


Magnetic Resonance Imaging In Medicine: Quantitative Tissue Characterization, Gary H. Glover Jan 1985

Magnetic Resonance Imaging In Medicine: Quantitative Tissue Characterization, Gary H. Glover

Review of Progress in Quantitative Nondestructive Evaluation

The medical community has long practiced the art of nondestructive evaluation in its various diagnostic imaging branches. Only within about the last decade, however, has there been an attempt to provide quantitative information to the clinical radiologist. The most important example of a system providing such information is the computed x-ray tomography (CT) scanner. The resulting digitally created images portray maps of an approximation to the electron density at discrete sampling points within the subject. Density resolution of the order of 0.1% and spatial resolution reaching 0.5 mm have become readily available.


Geological Fracture Mapping Using Electromagnetic Geotomography, A. L. Ramirez, F. J. Deadrick, R. J. Lytle Jan 1983

Geological Fracture Mapping Using Electromagnetic Geotomography, A. L. Ramirez, F. J. Deadrick, R. J. Lytle

Review of Progress in Quantitative Nondestructive Evaluation

This article describes the evaluation of a new geophysical technique used to map fractures between boreholes: electromagnetic geotomography used in conjunction with salt water tracers. An experiment has been performed in a granitic rock mass. Geotomographic images have been generated and compared with borehole geophysical data: neutron logs, acoustic velocity logs, caliper logs and acoustic televiewer records. Comparisons between the images and the geophysical logs indicate that clusters of fractures were detected but single fractures were not.


Studies Of Electromagnetic Sound Generation For Nde, Thomas J. Moran Jan 1974

Studies Of Electromagnetic Sound Generation For Nde, Thomas J. Moran

Review of Progress in Quantitative Nondestructive Evaluation

This paper will first provide a brief review of the physics of the electromagnetic generation process in metals and semiconductors and secondly, a discussion of the goals of our present project involving the application of this technique to NDE.