Analysis Of Various Classification Techniques For Computer Aided Detection System Of Pulmonary Nodules In Ct, 2017 University of Dayton

#### Analysis Of Various Classification Techniques For Computer Aided Detection System Of Pulmonary Nodules In Ct, Barath Narayanan Narayanan, Russell C. Hardie, Temesguen Messay

*Russell C. Hardie*

Lung cancer is the leading cause of cancer death in the United States. It usually exhibits its presence with the formation of pulmonary nodules. Nodules are round or oval-shaped growth present in the lung. Computed Tomography (CT) scans are used by radiologists to detect such nodules. Computer Aided Detection (CAD) of such nodules would aid in providing a second opinion to the radiologists and would be of valuable help in lung cancer screening. In this research, we study various feature selection methods for the CAD system framework proposed in FlyerScan. Algorithmic steps of FlyerScan include (i) local contrast enhancement (ii ...

Recursive Non-Local Means Filter For Video Denoising, 2017 University of Dayton

#### Recursive Non-Local Means Filter For Video Denoising, Redha A. Ali, Russell C. Hardie

*Russell C. Hardie*

In this paper, we propose a computationally efficient algorithm for video denoising that exploits temporal and spatial redundancy. The proposed method is based on non-local means (NLM). NLM methods have been applied successfully in various image denoising applications. In the single-frame NLM method, each output pixel is formed as a weighted sum of the center pixels of neighboring patches, within a given search window. The weights are based on the patch intensity vector distances. The process requires computing vector distances for all of the patches in the search window. Direct extension of this method from 2D to 3D, for video ...

Block Matching And Wiener Filtering Approach To Optical Turbulence Mitigation And Its Application To Simulated And Real Imagery With Quantitative Error Analysis, 2017 University of Dayton

#### Block Matching And Wiener Filtering Approach To Optical Turbulence Mitigation And Its Application To Simulated And Real Imagery With Quantitative Error Analysis, Russell C. Hardie, Michael Armand Rucci, Barry K. Karch, Alexander J. Dapore

*Russell C. Hardie*

We present a block-matching and Wiener filtering approach to atmospheric turbulence mitigation for long-range imaging of extended scenes. We evaluate the proposed method, along with some benchmark methods, using simulated and real-image sequences. The simulated data are generated with a simulation tool developed by one of the authors. These data provide objective truth and allow for quantitative error analysis. The proposed turbulence mitigation method takes a sequence of short-exposure frames of a static scene and outputs a single restored image. A block-matching registration algorithm is used to provide geometric correction for each of the individual input frames. The registered frames ...

Simulation Of Anisoplanatic Imaging Through Optical Turbulence Using Numerical Wave Propagation With New Validation Analysis, 2017 University of Dayton

#### Simulation Of Anisoplanatic Imaging Through Optical Turbulence Using Numerical Wave Propagation With New Validation Analysis, Russell C. Hardie, Jonathan D. Power, Daniel A. Lemaster, Douglas R. Droege, Szymon Gladysz, Santasri Bose-Pillai

*Russell C. Hardie*

We present a numerical wave propagation method for simulating imaging of an extended scene under anisoplanatic conditions. While isoplanatic simulation is relatively common, few tools are specifically designed for simulating the imaging of extended scenes under anisoplanatic conditions. We provide a complete description of the proposed simulation tool, including the wave propagation method used. Our approach computes an array of point spread functions (PSFs) for a two-dimensional grid on the object plane. The PSFs are then used in a spatially varying weighted sum operation, with an ideal image, to produce a simulated image with realistic optical turbulence degradation. The degradation ...

Differential Tilt Variance Effects Of Turbulence In Imagery: Comparing Simulation With Theory, 2017 Air Force Research Laboratory

#### Differential Tilt Variance Effects Of Turbulence In Imagery: Comparing Simulation With Theory, Daniel A. Lemaster, Russell C. Hardie, Szymon Gladysz, Matthew D. Howard, Michael Armand Rucci, Matthew E. Trippel, Jonathan D. Power, Barry K. Karch

*Russell C. Hardie*

Differential tilt variance is a useful metric for interpreting the distorting effects of turbulence in incoherent imaging systems. In this paper, we compare the theoretical model of differential tilt variance to simulations. Simulation is based on a Monte Carlo wave optics approach with split step propagation. Results show that the simulation closely matches theory. The results also show that care must be taken when selecting a method to estimate tilts.

Second Order Phase Transition Temperature Of Single Crystals Of Gd5si1.3ge2.7 And Gd5si1.4ge2.6, 2017 Iowa State University

#### Second Order Phase Transition Temperature Of Single Crystals Of Gd5si1.3ge2.7 And Gd5si1.4ge2.6, Ravi L. Hadimani, Yevgen Melikhov, Deborah L. Schlagel, Thomas A. Lograsso, Kevin W. Dennis, R. William Mccallum, David C. Jiles

*Thomas A. Lograsso*

Gd5(Six Ge 1−x)4 has mixed phases in the composition range 0.32 < x < 0.41, which have not been widely studied. In this paper, we have synthesized and indexed single crystal samples of Gd5Si1.3 Ge 2.7 and Gd5Si1.4 Ge 2.6. We have investigated the first order and second orderphase transition temperatures of these samples using magnetic moment vs. temperature andmagnetic moment vs. magnetic field at different temperatures. We have used a modified Arrott plot technique that was developed and reported by us previously to determine the “hidden” second order phase transition temperature of ...

Gd5(Si,Ge)4 Thin Film Displaying Large Magnetocaloric And Strain Effects Due To Magnetostructural Transition, 2017 Iowa State University

#### Gd5(Si,Ge)4 Thin Film Displaying Large Magnetocaloric And Strain Effects Due To Magnetostructural Transition, Ravi L. Hadimani, Joao H. B. Silva, Andre M. Pereira, Devo L. Schlagel, Thomas A. Lograsso, Yang Ren, David C. Jiles, Joao P. Araújo

*Thomas A. Lograsso*

Magnetic refrigeration based on the magnetocaloric effect is one of the best alternatives to compete with vapor-compression technology. Despite being already in its technology transfer stage, there is still room for optimization, namely, on the magnetic responses of the magnetocaloric material. In parallel, the demand for different magnetostrictive materials has been greatly enhanced due to the wide and innovative range of technologies that emerged in the last years (from structural evaluation to straintronics fields). In particular, the Gd5(Six Ge1−x)4 compounds are a family of well-known alloys that present both giant magnetocaloric and colossal magnetostriction effects. Despite their ...

A Graph-Based Formulation For Computational Characterization Of Bulk Heterojunction Morphology, 2017 Iowa State University

#### A Graph-Based Formulation For Computational Characterization Of Bulk Heterojunction Morphology, Olga Wodo, Srikanta Tirthapura, Sumit Chaudhary, Baskar Ganapathysubramanian

*Srikanta Tirthapura*

To improve the efficiency of organic solar cells, it is essential to understand the role of morphology and to tailor fabrication process to get desired morphologies. In this context, a comprehensive set of computational tools to quantify and classify the 2D/3D heterogeneous internal structure of thin films is invaluable. We present a graph-based framework to efficiently compute a broad suite of physically meaningful morphology descriptors. These morphology descriptors are further classified according to the physical subprocesses within OSCs – photon absorption, exciton diffusion, charge separation, and charge transport. This approach is motivated by the equivalence between a discretized 2D/3D ...

Computational Eddy-Current Probe Model For Composites, Metals And Semiconductors, 2017 Sabbagh Associates, Inc.

#### Computational Eddy-Current Probe Model For Composites, Metals And Semiconductors, L. David Sabbagh, John R. Bowler, Harold A. Sabbagh

*John R. Bowler*

A comprehensive computer code for research and design studies in electromagnetic NDE is now at an advanced stage of development. It has the capability of predicting the impedance characteristics of fully three-dimensional eddy-current probes in the presence of metals, semiconductors and advanced composites. By using a combination of the conjugate gradient method applied to a matrix and fast Fourier transform techniques, the resulting algorithm is both efficient in CPU time and has modest storage requirements. The theoretical model was presented in [1].

Eddy Current Probe Impedances Due To Interaction With Advanced Composites, 2017 Sabbagh Associates, Inc.

#### Eddy Current Probe Impedances Due To Interaction With Advanced Composites, John R. Bowler, Harold A. Sabbagh, L. David Sabbagh

*John R. Bowler*

Electromagnetic fields in uniaxial conductors have been studied in order to examine the induced current distributions excited by external alternating current sources. The problem is motivated by the need to evaluate eddy current testing techniques for the inspection of composites such as graphite-epoxy or boron-epoxy. In particular it is important to understand how eddy currents behave in anisotropic materials, especially uniaxial conductors in which the conductivity in the axial direction may be several hundred times greater than the transverse conductivity [1].

Prediction And Analysis Of Transient Eddy-Current Probe Signals, 2017 University of Surrey

#### Prediction And Analysis Of Transient Eddy-Current Probe Signals, J. R. Bowler

*John R. Bowler*

In eddy-current nondestructive evaluation, the electromagnetic field is usually excited by a probe carrying a time-harmonic current and flaw information inferred from the amplitude and phase of the probe signal. In principle, transient excitation of eddy-currents would seem to offer great advantages since the probe response contains the equivalent information of a spectrum of frequencies. This paper explores a number of basic transient solutions due to normal air-cored coils and shows how the induced emf in a coil is related to its coupling coefficient.

Inversion Of Eddy Current Probe Impedance Data For Crack Reconstruction, 2017 University of Surrey

#### Inversion Of Eddy Current Probe Impedance Data For Crack Reconstruction, John Bowler, D. J. Harrison, S. J. Norton

*John R. Bowler*

The aim of eddy current inversion is to reconstruct an unknown flaw from probe signals measured as a function of probe position and frequency or time. In seeking the solution of an inverse problem, one can take advantage of an ability to solve forward problems by using predictions of probe signals calculated with a tentative estimate of the flaw. A well known inversion strategy adopted here for eddy current inversion, is that of varying the flaw estimate iteratively until the disparity between predicted and observed probe signals is minimized. Then the model flaw which gives the optimum predictions of the ...

Eddy Current Field Theory For A Flawed Conducting Half-Space, 2017 University of Surrey

#### Eddy Current Field Theory For A Flawed Conducting Half-Space, John R. Bowler

*John R. Bowler*

By using dyadic Green’s functions the electromagnetic field in an unflawed conducting half-space can be found for a general alternating current source distribution. A crack in the conductor gives rise to a secondary source which may be represented as a surface distribution of current dipoles. An integral equation for the secondary source distribution is derived and the dipole density evaluated numerically for a rectangular subsurface crack.

Eddy-Current Probe Interaction With Subsurface Cracks, 2017 University of Surrey

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

*John R. Bowler*

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 ...

Pulsed Eddy-Current Measurements For The Characterization Of Thin Layers And Surface Treatments, 2017 Iowa State University

#### Pulsed Eddy-Current Measurements For The Characterization Of Thin Layers And Surface Treatments, M. J. Johnson, John R. Bowler

*John R. Bowler*

By using a transient excitation, eddy-current probes exhibit a diffuse pulse-echo response in the presence of stratified conductors. The response has been investigated in order to evaluate pulsed eddy-current signals due to a single conducting layer over a uniform substrate of dissimilar conductivity. The aim of the investigation is to assess the feasibility of measuring the thickness and quality of surface treatments including the diffusion of aluminum into nickel parts and the case hardening of steel components.

Prediction Of Eddy-Current Probe Impedance Due To Surface Cracks In Ferromagnetic Steels, 2017 University of Surrey

#### Prediction Of Eddy-Current Probe Impedance Due To Surface Cracks In Ferromagnetic Steels, N. Harfield, John R. Bowler

*John R. Bowler*

Ferromagnetic steels usually have a high value of relative permeability which means that, for frequencies commonly used in eddy-current non-destructive evaluation, the electromagnetic skin-depth is typically much smaller than the depth of a crack. This behavior allows the use of approximate, thin-skin theories to describe the interaction between induced eddy-currents and surface-breaking cracks in steel. Thin-skin approximations are also appropriate for use with non-magnetic materials at sufficiently high frequency. Auld et al [1] treated the high-frequency, surface-crack problem in aluminium using a magnetic scalar potential formulation. The surface impedance boundary condition was applied to the field on the crack faces ...

Measurement And Calculation Of Transient Eddy-Currents In Layered Structures, 2017 University of Surrey

#### Measurement And Calculation Of Transient Eddy-Currents In Layered Structures, John R. Bowler, D. J. Harrison

*John R. Bowler*

In transient eddy-current inspection, an electromagnetic field pulse is excited in a conductor by causing a step change in the current through a coil. As this pulse propagates into the material, it is broadened by dispersion and scattered by discontinuities in the conductivity and permeability of the conductor. Subsurface defects cause part of the pulse to be scattered back to the surface of the conductor where it can be observed as a transient signal in the time domain, either as an EMF across the coil, or by direct measurement of the magnetic field using, for example, a Hall sensor. The ...

Highly Directional Receiver And Source Antennas Using Photonic Band Gap Crystals, 2017 Iowa State University

#### Highly Directional Receiver And Source Antennas Using Photonic Band Gap Crystals, Rana Biswas, Gary L. Tuttle, Ekmel Ozbay, Burak Temelkuran, Mihail Sigalas, Kai-Ming Ho

*Gary Tuttle*

A directional antenna made with photonic band gap structures has been presented. The directional antenna is formed with two photonic band gap structures oriented back to back and separated from each other by a distance to form a resonant cavity between the photonic band gap structures. An antenna element is placed in the resonant cavity. The resonant frequency of the cavity is tuned by adjusting the distance between the photonic band gap structures. The resonant cavity can be asymmetrical or symmetrical.

Ferromagnetism Of Magnetically Doped Topological Insulators In Crxbi2− Xte3 Thin Films, 2017 Iowa State University

#### Ferromagnetism Of Magnetically Doped Topological Insulators In Crxbi2− Xte3 Thin Films, Yan Ni, Z. Zhang, Ikenna C. Nlebedim, M. Ravi Hadimani, Gary L. Tuttle, David C. Jiles

*Gary Tuttle*

We investigated the effect of magnetic doping on magnetic and transport properties of Bi2Te3thin films. CrxBi2−xTe3 thin films with x = 0.03, 0.14, and 0.29 were grown epitaxially on mica substrate with low surface roughness (∼0.4 nm). It is found that Cr is an electron acceptor in Bi2Te3 and increases the magnetization of CrxBi2−xTe3. When x = 0.14 and 0.29,ferromagnetism appears in CrxBi2−xTe3 thin films, where anomalous Hall effect and weak localization of magnetoconductance were observed. The Curie temperature, coercivity, and remnant Hall resistance of thin films increase with increasing Cr concentration ...

Implementation Of Range Autofocus For Sar Radar Imaging, 2017 Kennesaw State University

#### Implementation Of Range Autofocus For Sar Radar Imaging, Nicholas J. Testin, Philip Davis

*Honors College Capstones and Theses*

The range calculation for an FMCW radar depends on accurate linear modulation. In some circumstances, linear modulation may not be available and must be corrected for. This paper describes an autofocus technique used to correct for phase error due to non-linearities in the components of a FMCW radar. Also described here is the algorithm used in calculating the phase error and application of the phase correction with triangle modulation. Known errors were calculated at certain distances and applied to correcting the phase of data taken at similar distances. The results given were generated using a SAR working outside linear ranges.