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- Electrical and Computer Engineering Faculty Publications and Presentations (3)
- Electrical and Computer Engineering Faculty Research & Creative Works (3)
- Dissertations and Theses (2)
- Doctoral Dissertations (2)
- Faculty Publications (2)
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- Nicola Bowler (2)
- All Graduate Theses and Dissertations, Spring 1920 to Summer 2023 (1)
- LSU Master's Theses (1)
- Masters Theses (1)
- Orfeas Kypris (1)
- The 8th International Conference on Physical and Numerical Simulation of Materials Processing (1)
- Theses and Dissertations (1)
- Turkish Journal of Electrical Engineering and Computer Sciences (1)
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Articles 1 - 21 of 21
Full-Text Articles in Engineering
Nondestructive Electromagnetic Characterization Of Uniaxial Sheet Media Using A Two-Flanged Rectangular Waveguide Probe, Neil G. Rogers, Michael J. Havrilla, Milo W. Hyde Iv, Alexander G. Knisely
Nondestructive Electromagnetic Characterization Of Uniaxial Sheet Media Using A Two-Flanged Rectangular Waveguide Probe, Neil G. Rogers, Michael J. Havrilla, Milo W. Hyde Iv, Alexander G. Knisely
Faculty Publications
Excerpt: Recent advancements in fabrication capabilities have renewed interest in the electromagnetic characterization of complex media, as many metamaterials are anisotropic and/or inhomogeneous. Additionally, for composite materials, anisotropy can be introduced by load, strain, misalignment, or damage through the manufacturing process [1], [2]. Methods for obtaining the constitutive parameters for isotropic materials are well understood and widely employed [3]–[8]. Therefore, it is crucial to develop a practical method for the electromagnetic characterization of anisotropic materials.
Physics-Based Signal Processing Methods For Terahertz Non-Destructive Evaluation Of Layered Media, Scott G. Schecklman
Physics-Based Signal Processing Methods For Terahertz Non-Destructive Evaluation Of Layered Media, Scott G. Schecklman
Dissertations and Theses
In recent years Terahertz (THz) time domain spectroscopy has emerged as a promising new technology with potential applications in a variety of fields, including industrial manufacturing, security screening and medical imaging. Pulsed THz systems are uniquely suited for non-destructive evaluation (NDE) of the sub-surface layers of dielectric packaging and coating materials, because they provide high dynamic range over a wide bandwidth in the far infrared portion of the electromagnetic spectrum. Often the dielectric materials of the packaging and/or surface coating layers exhibit relatively low loss and abrupt changes in the refractive index at the layer boundaries can be observed as …
Passively-Coded Embedded Microwave Sensors For Materials Characterization And Structural Health Monitoring (Shm), Katelyn Rose Brinker
Passively-Coded Embedded Microwave Sensors For Materials Characterization And Structural Health Monitoring (Shm), Katelyn Rose Brinker
Masters Theses
"Monitoring and maintaining civil, space, and aerospace infrastructure is an ongoing critical problem facing our nation. As new complex materials and structures, such as multilayer composites and inflatable habitats, become ubiquitous, performing inspection of their structural integrity becomes even more challenging. Thus, novel nondestructive testing (NDT) methods are needed. Chipless RFID is a relatively new technology that has the potential to address these needs. Chipless RFID tags have the advantage of being wireless and passive, meaning that they do not require a power source or an electronic chip. They can also be used in a variety of sensing applications including …
Hardware Architectures For Compact Microwave And Millimeter Wave Cameras, Matthew Jared Horst
Hardware Architectures For Compact Microwave And Millimeter Wave Cameras, Matthew Jared Horst
Doctoral Dissertations
"Millimeter wave SAR imaging has shown promise as an inspection tool for human skin for characterizing burns and skin cancers. However, the current state-of-the-art in microwave camera technology is not yet suited for developing a millimeter wave camera for human skin inspection. Consequently, the objective of this dissertation has been to build the necessary foundation of research to achieve such a millimeter wave camera. First, frequency uncertainty in signals generated by a practical microwave source, which is prone to drift in output frequency, was studied to determine its effect on SAR-generated images. A direct relationship was found between the level …
Development Of Active Microwave Thermography For Structural Health Monitoring, Ali Foudazi
Development Of Active Microwave Thermography For Structural Health Monitoring, Ali Foudazi
Doctoral Dissertations
"Active Microwave Thermography (AMT) is an integrated nondestructive testing and evaluation (NDT&E) method that incorporates aspects of microwave NDT and thermography techniques. AMT uses a microwave excitation to generate heat and the surface thermal profile of the material or structure under test is subsequently measured using a thermal camera (or IR camera). Utilizing a microwave heat excitation provides advantages over traditional thermal excitations (heat lamps, etc.) including the potential for non-contact, selective and focused heating. During an AMT inspection, two heating mechanisms are possible, referred to as dielectric and induction heating. Dielectric heating occurs as a result of the interaction …
An Electronic Portable Device Design To Spectroscopically Assess Fruit Quality, Ali̇ Sarikaş, Merve Doğruyol Başar
An Electronic Portable Device Design To Spectroscopically Assess Fruit Quality, Ali̇ Sarikaş, Merve Doğruyol Başar
Turkish Journal of Electrical Engineering and Computer Sciences
As a rapid and nondestructive sensing technique, reflection spectroscopy is useful in monitoring and managing horticultural production; in other words, the ripening of fruits and vegetables can be evaluated using reflection spectroscopy. Based on laboratory data obtained from an ultraviolet/visible/near-infrared (UV/Vis/NIR) spectrophotometer with a diffuse reflectance accessory, we developed a prototype handheld device. The device operates at a range of 400 nm to 1100 nm (blue, green, red, and NIR). LEDs, photodiodes, a microcontroller, digital-to-analog converters, a graphical LCD display, and a keypad were used for instrumentation. With our user-friendly software interface, measurements can be performed and controlled in real …
Nondestructive Testing And Structural Health Monitoring Based On Adams And Svm Techniques, Gang Jiang, Yi Ming Deng, Ji Tai Niu
Nondestructive Testing And Structural Health Monitoring Based On Adams And Svm Techniques, Gang Jiang, Yi Ming Deng, Ji Tai Niu
The 8th International Conference on Physical and Numerical Simulation of Materials Processing
No abstract provided.
Physics-Based Imaging Methods For Terahertz Nondestructive Evaluation Applications, Gabriel Paul Kniffin
Physics-Based Imaging Methods For Terahertz Nondestructive Evaluation Applications, Gabriel Paul Kniffin
Dissertations and Theses
Lying between the microwave and far infrared (IR) regions, the "terahertz gap" is a relatively unexplored frequency band in the electromagnetic spectrum that exhibits a unique combination of properties from its neighbors. Like in IR, many materials have characteristic absorption spectra in the terahertz (THz) band, facilitating the spectroscopic "fingerprinting" of compounds such as drugs and explosives. In addition, non-polar dielectric materials such as clothing, paper, and plastic are transparent to THz, just as they are to microwaves and millimeter waves. These factors, combined with sub-millimeter wavelengths and non-ionizing energy levels, makes sensing in the THz band uniquely suited for …
A Clamped Dual-Ridged Waveguide Measurement System For The Broadband, Nondestructive Characterization Of Sheet Materials, Milo W. Hyde Iv, Michael J. Havrilla
A Clamped Dual-Ridged Waveguide Measurement System For The Broadband, Nondestructive Characterization Of Sheet Materials, Milo W. Hyde Iv, Michael J. Havrilla
Faculty Publications
A novel two-port probe which uses dual-ridged waveguides for the nondestructive, broadband characterization of sheet materials is presented. The new probe is shown to possess approximately 2 to 3 times the bandwidth of traditional coaxial and rectangular/circular waveguide probe systems while maintaining the structural robustness characteristic of rectangular/circular waveguide probe systems. The theoretical development of the probe is presented, namely, by applying Love’s equivalence theorem and enforcing the continuity of transverse fields at the dual-ridged waveguide apertures, a system of coupled magnetic field integral equations is derived. The system of coupled magnetic field integral equations is solved using the method …
Experimental Verification Of The Linear Relationship Between Stress And The Reciprocal Of The Peak Barkhausen Voltage In Astm A36 Steel, Orfeas Kypris, Ikenna Nlebedim, David Jiles
Experimental Verification Of The Linear Relationship Between Stress And The Reciprocal Of The Peak Barkhausen Voltage In Astm A36 Steel, Orfeas Kypris, Ikenna Nlebedim, David Jiles
Orfeas Kypris
This study presents an experimental validation of a model theory for determining the relationship between a nondestructive measurement parameter and a property of interest. It was found that the reciprocal of the peak envelope amplitude of the Barkhausen emission voltage follows a linear relationship with stress. A linear relationship between stress and the reciprocal of the root mean square voltage was also obtained. These observations represent an important step towards improving the use of Barkhausen signals for magnetic non-destructive evaluation of stress as a function of depth in ferromagnetic load bearing structures.
Document Flash Thermography, Cory A. Larsen
Document Flash Thermography, Cory A. Larsen
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
This thesis presents the application of ash thermography techniques to the analysis of documents. The motivation for this research is to develop the ability to non-destructively reveal covered writings in archaeological artifacts such as the Codex Selden or Egyptian car- tonnage. Current common signal processing techniques are evaluated for their effectiveness in enhancing subsurface writings found within a set of test documents. These processing techniques include: false colorization, contrast stretching, histogram equalization, median altering, Gaussian low-pass altering, layered signal reconstruction and thermal signal reconstruction (TSR), several contrast image definitions, differential absolute contrast (DAC), correlated contrast, derivative images, principal component thermography …
Inverse Scattering Image Quality With Noisy Forward Data, Thomas J. Sorensen
Inverse Scattering Image Quality With Noisy Forward Data, Thomas J. Sorensen
Theses and Dissertations
Image quality metrics for several inverse scattering methods and algorithms are presented. Analytical estimates and numerical simulations provide a basis for poor image quality diagnostics. The limitations and noise behavior of reconstructed images are explored analytically and empirically using a contrast ratio. Theoretical contrast ratio estimates using the canonical PEC circular cylinder are derived. Empirical studies are conducted to confirm theoretical estimates and to provide examples of image quality vs SNR for more complex scatterer profiles. Regularized sampling is shown to be more noise sensitive than tomographic reconstructive methods.
Microwave And Millimeter Wave Nondestructive Testing And Evaluation -- Overview And Recent Advances, Sergey Kharkovsky, R. Zoughi
Microwave And Millimeter Wave Nondestructive Testing And Evaluation -- Overview And Recent Advances, Sergey Kharkovsky, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
This article focuses on three recent applications of microwave and millimeter wave NDT&E techniques that involve novel instrumentation development and measurements, including: 1) disbond detection in strengthened concrete bridge members retrofitted with carbon fiber reinforced polymer (CFRP) composite laminates; 2) corrosion and precursor pitting detection in painted aluminum and steel substrates; and 3) detection of flaws in spray-on foam insulation and the acreage heat tiles of the Space Shuttle through focused and synthetic imaging techniques. These applications have been performed at the Applied Microwave Nondestructive Testing Laboratory (amntl) at the University of Missouri-Rolla.
Oct-Based Elastography For Large And Small Deformations, Donald D. Duncan, Sean J. Kirkpatrick, Ruikang K. Wang
Oct-Based Elastography For Large And Small Deformations, Donald D. Duncan, Sean J. Kirkpatrick, Ruikang K. Wang
Electrical and Computer Engineering Faculty Publications and Presentations
We present two approaches to speckle tracking for optical coherence tomography (OCT)-based elastography, one appropriate for small speckle motions and the other for large, rapid speckle motions. Both approaches have certain advantages over traditional cross-correlation based motion algorithms. We apply our algorithms to quantifying the strain response of a mechanically inhomogeneous, bi-layered polyvinyl alcohol tissue phantom that is subjected to either small or large dynamic compressive forces while being imaged with a spectral domain OCT system. In both the small and large deformation scenarios, the algorithms performed well, clearly identifying the two mechanically disparate regions of the phantom. The stiffness …
Imaging The Mechanical Stiffness Of Skin Lesions By In Vivo Acousto-Optical Elastography, Sean J. Kirkpatrick, Donald D. Duncan, Ruikang K. Wang, Molly Kulesz-Martin, Ken Lee
Imaging The Mechanical Stiffness Of Skin Lesions By In Vivo Acousto-Optical Elastography, Sean J. Kirkpatrick, Donald D. Duncan, Ruikang K. Wang, Molly Kulesz-Martin, Ken Lee
Electrical and Computer Engineering Faculty Publications and Presentations
Optical elastography is an imaging modality that relies on variations in the local mechanical properties of biological tissues as the contrast mechanism for image formation. Skin lesions, such as melanomas and other invasive conditions, are known to alter the arrangement of collagen fibers in the skin and thus should lead to alterations in local skin mechanical properties. We report on an acousto-optical elastography (AOE) imaging modality for quantifying the mechanical behavior of skin lesions. The method relies upon stimulating the tissue with a low frequency acoustic force and imaging the resulting strains in the tissue by means of quantifying the …
Comparison Of Near-Field Millimeter-Wave Probes For Detecting Corrosion Precursor Pitting Under Paint, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, Russell A. Austin
Comparison Of Near-Field Millimeter-Wave Probes For Detecting Corrosion Precursor Pitting Under Paint, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, Russell A. Austin
Electrical and Computer Engineering Faculty Research & Creative Works
Aircraft structural components such as wings and fuselages are constantly exposed to harsh environments, which make them susceptible to corrosion initiation and growth. To complicate matters, corrosion is normally hidden under paint and primer and cannot be visually detected until significant corrosion has occurred, causing the paint to blister. Corrosion of this type is usually preceded by the presence of corrosion precursor pitting. Hence, early detection of pitting is a critical issue in the maintenance of an aircraft and its structural components. Near-field microwave nondestructive testing techniques have been successfully used for detection of corrosion under paint, including very small …
Blind Multiridge Detection And Reconstruction Using Ultrasonic Signals, Rekha Katragadda
Blind Multiridge Detection And Reconstruction Using Ultrasonic Signals, Rekha Katragadda
LSU Master's Theses
Time-frequency signal analysis has been widely applied in the modern radar, acoustic, sonar and ultrasonic signal processing techniques. Recently, the nondestructive testing (NDT) techniques via the ultrasonic instrumentation have shown the striking capability of the quality control for the material fabrication industry. In this thesis, we first provide a general mathematical model for the ultrasonic signals collected by pulse-echo sensors and then design a totally blind, novel, signal processing NDT technique relying on neither a priori signal information nor any manual effort. The signature signal can be blindly extracted by using the automatic optimal frame size selection for further modeling …
Performance Analysis Of A Maximum-Likelihood Speckle Motion Estimator, Donald D. Duncan, Sean J. Kirkpatrick
Performance Analysis Of A Maximum-Likelihood Speckle Motion Estimator, Donald D. Duncan, Sean J. Kirkpatrick
Electrical and Computer Engineering Faculty Publications and Presentations
Presented herein is a performance analysis of a maximum likelihood estimator for calculating small speckle motions. Such estimators are important in a variety of speckle techniques used in non-destructive evaluation. The analysis characterizes the performance (bias and RMS deviation) of the estimator as a function of the signal-to-noise ratio. This SNR parameter is a convenient surrogate for decorrelation of sequential speckle patterns such as are seen in biological tissues. Although the particular estimator is predicated on speckle motions that are a small fraction of a pixel, accurate performance is demonstrated for instantaneous motions of up to ±0.8 pixel/record. Beyond this …
Theory Of Thin-Skin Eddy-Current Interaction With Surface Cracks, Nicola Harfield, John R. Bowler
Theory Of Thin-Skin Eddy-Current Interaction With Surface Cracks, Nicola Harfield, John R. Bowler
Nicola Bowler
Eddy-current non-destructive evaluation is commonly performed at relatively high frequencies at which the skin depths are significantly smaller than the dimensions of a typical crack. A thin-skin analysis of eddy currents is presented in which the electromagnetic fields on the crack faces are described in terms of a potential which obeys a two-dimensional Laplace equation. Solutions of this equation for defects in both magnetic and non-magnetic materials are determined by applying thin-skin boundary conditions at the crack perimeter. The impedance change of an eddy-current coil due to the defect is then calculated by numerical evaluation of one-dimensional integrals over the …
Low‐Frequency Perturbation Theory In Eddy‐Current Non‐Destructive Evaluation, Nicola Harfield, Y. Yoshida, John R. Bowler
Low‐Frequency Perturbation Theory In Eddy‐Current Non‐Destructive Evaluation, Nicola Harfield, Y. Yoshida, John R. Bowler
Nicola Bowler
A method is presented by which series solutions for the impedance change in an eddy‐current test probe due to closed cracks in a non‐magnetic, conducting half‐space can be derived at low frequency. The series solution is applicable for flaws whose dimensions are much smaller than the electromagnetic skin‐depth. The problem is formulated using an approach in which the flaw is represented by an equivalent distribution of current dipoles. The electric field scattered by the flaw is then written as an integral, over the flaw, of the product of the dipole density distribution and an appropriate Green’s function. Terms in the …
Microwave Nondestructive Detection And Evaluation Of Disbonding And Delamination In Layered-Dielectric Slabs, R. Zoughi, Sasan Bakhtiari
Microwave Nondestructive Detection And Evaluation Of Disbonding And Delamination In Layered-Dielectric Slabs, R. Zoughi, Sasan Bakhtiari
Electrical and Computer Engineering Faculty Research & Creative Works
A microwave nondestructive technique for detection and evaluation of disbonding and delamination in layered-dielectric-slabs backed by a conducting plate is discussed. The theoretical development begins by considering an incident wave illuminating such a medium and then formulating the characteristics of the wave reflected by the metal plate. An effective reflection coefficient is determined in this way whose phase characteristics are used in the detection and evaluation of delaminations in the media. The characteristics of this phase as a function of several parameters such as delamination dielectric constant and thickness, slab dielectric constant, and thickness and the frequency of operation are …