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 Physics, Mechanical, Engineering (2)
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 Aerospace engineering and engineering mechanics (1)
 Engineering mechanics (1)
 Barkhausen effects (1)
 Clickevoked otoacoustic emisssions (1)
 Ferromagnetic materials (1)
 Electrical hysteresis (1)
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 Blade (1)
 Annealing (1)
 Fiber amplifier (1)
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 Ferromagnetism (1)
 Elasticity (1)
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 Publication

 Retrospective Theses and Dissertations (6)
 Ames Laboratory Publications (4)
 Mechanical & Aerospace Engineering Theses & Dissertations (2)
 Duane D. Johnson (2)
 Faculty Publications (2)

 Alexander H. King (1)
 Electrical and Computer Engineering Faculty Publications (1)
 Electrical & Computer Engineering Faculty Publications (1)
 Materials Science and Engineering Publications (1)
 Electrical Engineering Faculty Publications (1)
 Journal of the Arkansas Academy of Science (1)
 Rocky Mountain Conference on Magnetic Resonance (1)
 ElectroOptics and Photonics Faculty Publications (1)
 Mechanical Engineering Faculty Publications (1)
 Dissertations, Theses, and Masters Projects (1)
 Jacek Smurzynski (1)
 Center for Nondestructive Evaluation Publications (1)
 Physics (1)
 Marc A. Fagelson (1)
 Publication Type
Articles 1  30 of 30
FullText Articles in Physics
OpticalFiber Preamplifiers For Ladar Detection And Associated Measurements For Improving The SignalToNoise Ratio, Michael S. Salisbury, Paul F. Mcmanamon, Bradley D. Duncan
OpticalFiber Preamplifiers For Ladar Detection And Associated Measurements For Improving The SignalToNoise Ratio, Michael S. Salisbury, Paul F. Mcmanamon, Bradley D. Duncan
ElectroOptics and Photonics Faculty Publications
In an effort to increase achievable postdetection signaltonoise ratios (SNRs) of continuouswave, 1gm allsolidstate ladar systems, a prototype rareearthdoped opticalfiber amplifier has been included in the optical return signal path of both a heterodyne and a directdetection ladar system. We provide numerical predictions for SNR increases according to our previously developed theory. We also detail our experimental efforts and provide the results of SNR measurements for four distinct cases: direct ladar detection with and without a fiber amplifier, and heterodyne ladar detection with and without a fiber amplifier. Experimentally measured increases in SNRs for ladar systems incorporating an opticalfiber amplifier ...
The Spectral Center Of Gravity Effect And Auditory Filter Bandwidth, Marc Fagelson, Linda M. Thibodeau
The Spectral Center Of Gravity Effect And Auditory Filter Bandwidth, Marc Fagelson, Linda M. Thibodeau
Marc A. Fagelson
Recent Developments In Modeling Of The Stress Derivative Of Magnetization In Ferromagnetic Materials, David C. Jiles, Michael K. Devine
Recent Developments In Modeling Of The Stress Derivative Of Magnetization In Ferromagnetic Materials, David C. Jiles, Michael K. Devine
Ames Laboratory Publications
The effect of changing stress on the magnetization of ferromagnetic materials leads to behavior in which the magnetization may increase, or decrease, when exposed to the same stress under the same external conditions. A simple empirical law seems to govern the behavior when the magnetization begins from a major hysteresis loop. The application of the law of approach, in which the derivative of the magnetization with respect to the elastic energy supplied dM/dW is proportional to the magnetization displacement M _{an}−M, is discussed.
Frequency Dependence Of Hysteresis Curves In Conducting Magnetic Materials, David C. Jiles
Frequency Dependence Of Hysteresis Curves In Conducting Magnetic Materials, David C. Jiles
Ames Laboratory Publications
An extension of the hysteresis model has been developed that takes into account the effects on the hysteresis curves of eddycurrents in electrically conducting media. In the derivation presented it is assumed that the frequency of the applied field is low enough (or the thickness of the material medium small enough) that the skin effect can be ignored so that the magnetic field penetrates uniformly throughout the material. In this case, the dc hysteresis equation is extended by the addition of a classical eddy‐current‐loss term depending on (i) the rate of change of magnetization with time, (ii) the ...
Estimation Of The FreeChargeCarrier Concentration In FastIon Conducting Na2sB2s3 Glasses From An Analysis Of The FrequencyDependent, Ernest F. Hairetdinov, Nikolai F. Uvarov, Hitendra K. Patel, Steve W. Martin
Estimation Of The FreeChargeCarrier Concentration In FastIon Conducting Na2sB2s3 Glasses From An Analysis Of The FrequencyDependent, Ernest F. Hairetdinov, Nikolai F. Uvarov, Hitendra K. Patel, Steve W. Martin
Materials Science and Engineering Publications
ac and dc conductivities of fastion conducting xNa2S+(1x)B2S3 glasses in the composition range 0.001≤x≤0.1 were analyzed using the AlmondWest formula σ(ν)=σdc[1+(ν/νH)α]. The hopping frequency for free charge carriers νH, the dc conductivity σdc, and their respective activation energies were determined. The concentration of free charge carriers evaluated from the conductivities and estimated mobilities is in good agreement with the overall content of sodium cations in the glasses and it is proposed that this supports the concept of a strong and not weak electrolyte model for these ...
36th Rocky Mountain Conference On Analytical Chemistry
36th Rocky Mountain Conference On Analytical Chemistry
Rocky Mountain Conference on Magnetic Resonance
Program, abstracts, and information about the 36th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, cosponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 31  August 5, 1994.
Compositional ShortRange Ordering In Metallic Alloys: BandFilling, ChargeTransfer, And Size Effects From A FirstPrinciples AllElectron LandauType Theory, J. B. Staunton, Duane D. Johnson, F. J. Pinski
Compositional ShortRange Ordering In Metallic Alloys: BandFilling, ChargeTransfer, And Size Effects From A FirstPrinciples AllElectron LandauType Theory, J. B. Staunton, Duane D. Johnson, F. J. Pinski
Duane D. Johnson
Using a meanfield statistical description, we derive a general formalism to investigate atomic shortrange order in alloys based on a densityfunctional description of the finitetemperature, grand potential of the random alloy. This ‘‘firstprinciples,’’ Landautype approach attempts to treat several contributions (electronic structure, Fermi surface, electrostatics, magnetism, etc.) to the electronic energy on an equal footing. An important ingredient for the statistical averaging is the replacement of the molecular mean fields (Weiss fields) with Onsager cavity fields, which forces the diagonal part of the fluctuationdissipation theorem to be obeyed. To show its general applicability and usefulness, we apply the theory to ...
FirstPrinciples AllElectron Theory Of Atomic ShortRange Ordering In Metallic Alloys: D022 Versus L12Like Correlations, Duane D. Johnson, J. B. Staunton, F. J. Pinski
FirstPrinciples AllElectron Theory Of Atomic ShortRange Ordering In Metallic Alloys: D022 Versus L12Like Correlations, Duane D. Johnson, J. B. Staunton, F. J. Pinski
Duane D. Johnson
We use a ‘‘firstprinciples’’ concentrationwave approach based on a finitetemperature, electronic densityfunctional, meanfield, grand potential of the random alloy to investigate the hightemperature atomic shortrange order (ASRO) in Ni75V25 and Pd75V25 solid solutions. Experimentally, these similar alloys both develop D022type longrange order at low temperatures but different ASRO at high temperatures. Our calculations describe the measured ASRO well. We compare these results with those found for a hypothetical Co75Ti25 solid solution. Since this alloy orders directly from the melt into the L12 phase, it should exhibit strong L12like ASRO, as we find in our calculations. We analyze the features in ...
Direct Relation Between Fresnel's Interface Reflection Coefficients For The Parallel And Perpendicular Polarizations: Erratum 2, R. M.A. Azzam
Direct Relation Between Fresnel's Interface Reflection Coefficients For The Parallel And Perpendicular Polarizations: Erratum 2, R. M.A. Azzam
Electrical Engineering Faculty Publications
The record is set straight concerning two equations that determine the reflection phase shifts at a single interface from the intensity reflectances forp and spolarized light at one angle of incidence. These equations appeared previously in this journal [J. Opt. Soc. Am. 69, 1007 (1979); erratum, J. Opt. Soc. Am. 70, 261 (1980)].
SurfaceInduced Ordering In Asymmetric Block Copolymers, Y. Liu, W. Zhao, X. Zheng, Alexander H. King, A. Sing, M. H. Rafailovich, J. Sokolov, K. H. Dai, E. J. Kramer, S. A. Schwarz, O. Gebizlioglu, S. K. Sinha
SurfaceInduced Ordering In Asymmetric Block Copolymers, Y. Liu, W. Zhao, X. Zheng, Alexander H. King, A. Sing, M. H. Rafailovich, J. Sokolov, K. H. Dai, E. J. Kramer, S. A. Schwarz, O. Gebizlioglu, S. K. Sinha
Alexander H. King
The surfaceinduced ordering in thin films of asymmetric deuterated polystyrene (dPS) poly(viny1pyridine) (PVP) diblock and triblock copolymers of comparable polymerization index and PVP volume fraction  0.25) was studied using transmission electron microscopy, atomic force microscopy, secondary ion massspectrometry, and neutron reflectivity. The morphology of both di and triblock copolymer films was found to be cylindrical except for the layer adjacent to the silicon oxide surface, which due to the strong interaction of silica with PVP, was lamellar. The spacing between adjacent cylindrical layers was found to be consistent with mean field theory predictions. In the triblock copolymer films ...
Monitoring Neutron Embrittlement In Nuclear Pressure Vessel Steels Using Micromagnetic Barkhausen Emissions, Levent B. Sipahi, Madhav Rao Govindaraju, David C. Jiles
Monitoring Neutron Embrittlement In Nuclear Pressure Vessel Steels Using Micromagnetic Barkhausen Emissions, Levent B. Sipahi, Madhav Rao Govindaraju, David C. Jiles
Center for Nondestructive Evaluation Publications
In nuclear power plants, neutron embrittlement of pressure vessel steels has been one of the main concerns. The use of micromagnetic Barkhausen emissions is a promising method to monitor the variations in microstructural and subsurface stress states due to their influence on these emissions. Measurements of these emissions can reveal neutron irradiationdegradation in nuclear power plant components. Samples which were irradiated at differentneutron fluences and annealed at different temperatures were obtained from three reactor surveillance programs. The results of different neutron fluences and annealing procedures showed noticeable fractional changes in the magnetic Barkhausen effect signal parameter, ΔMBE/MBE, and in ...
Estimation Of Fatigue Exposure From Magnetic Coercivity, Z. J. Chen, David C. Jiles, J. Kameda
Estimation Of Fatigue Exposure From Magnetic Coercivity, Z. J. Chen, David C. Jiles, J. Kameda
Ames Laboratory Publications
An investigation of the effects of fatigue on A533B steel under constant load amplitude is reported in this paper. It was found that the plastic strain of the sample accumulated logarithmically with the number of stress cycles after initial fatigue softening. Based on the fact that plastic strain is often linearly related to the coercivity of material, at least for small changes of H _{c }, a phenomenological relationship has been developed and tested to correlate the number of stress cycles to this magnetic parameter. This result represents the first successful attempt to relate the fatigue exposure directly to a magnetic ...
Elastic Constants Of Bcc CuAlNi Alloys, Lluís Mañosa, M. Jurado, Antoni Planes, Jerel L. Zarestky, Thomas A. Lograsso, C. Stassis
Elastic Constants Of Bcc CuAlNi Alloys, Lluís Mañosa, M. Jurado, Antoni Planes, Jerel L. Zarestky, Thomas A. Lograsso, C. Stassis
Ames Laboratory Publications
We have measured the adiabatic elastic constants of two CuAlNi martensitic alloys using ultrasonic methods and we have compared the results to recent neutronscattering experiments. It is shown that the elastic behavior of CuAlNi alloys follows the same trends exhibited by other Cubased alloys; in particular, the TA2 longwavelength acoustic modes are softer than all other modes.
Flow Simulations About SteadyComplex And Unsteady Moving Configurations Using StructuredOverlapped And Unstructured Grids, James Charles Newman Iii
Flow Simulations About SteadyComplex And Unsteady Moving Configurations Using StructuredOverlapped And Unstructured Grids, James Charles Newman Iii
Mechanical & Aerospace Engineering Theses & Dissertations
The limiting factor in simulating flows past realistic configurations of interest has been the discretization of the physical domain on which the governing equations of fluid flow may be solved. In an attempt to circumvent this problem, many Computational Fluid Dynamic (CFD) methodologies that are based on different grid generation and domain decomposition techniques have been developed. However, due to the costs involved and expertise required, very few comparative studies between these methods have been performed. In the present work, the two CFD methodologies which show the most promise for treating complex threedimensional configurations as well as unsteady moving boundary ...
Rank Conditioned Rank Selection Filters For Signal Restoration, Russell C. Hardie, Kenneth E. Barner
Rank Conditioned Rank Selection Filters For Signal Restoration, Russell C. Hardie, Kenneth E. Barner
Electrical and Computer Engineering Faculty Publications
A class of nonlinear filters called rank conditioned rank selection (RCRS) filters is developed and analyzed in this paper. The RCRS filters are developed within the general framework of rank selection(RS) filters, which are filters constrained to output an order statistic from the observation set. Many previously proposed rank order based filters can be formulated as RS filters. The only difference between such filters is in the information used in deciding which order statistic to output. The information used by RCRS filters is the ranks of selected input samples, hence the name rank conditioned rank selection filters. The number ...
Click‐Evoked Otoacoustic Emissions In Normal‐Hearing Children, Jacek Smurzynski
Click‐Evoked Otoacoustic Emissions In Normal‐Hearing Children, Jacek Smurzynski
Jacek Smurzynski
Gravity And Electromagnetism In Noncommutative Geometry, Giovanni Landi, Nguyen Ai Viet, Kameshwar C. Wali
Gravity And Electromagnetism In Noncommutative Geometry, Giovanni Landi, Nguyen Ai Viet, Kameshwar C. Wali
Physics
We present a unified description of gravity and electromagnetism in the framework of a Z 2 noncommutative differential calculus. It can be considered as a “discrete version” of KaluzaKlein theory, where the fifth continuous dimension is replaced by two discrete points. We derive an action which coincides with the dimensionally reduced one of the ordinary KaluzaKlein theory.
Using The Cern ProgramLibrary Graphics And Interactive Data Display, Morgan T. Burks, Wilson H. Howe, Christine A. Byrd, Wilfred J. Braithwaite
Using The Cern ProgramLibrary Graphics And Interactive Data Display, Morgan T. Burks, Wilson H. Howe, Christine A. Byrd, Wilfred J. Braithwaite
Journal of the Arkansas Academy of Science
Small scale Monte Carlo programming is growing rapidly due to the ease with which complex problems may be formulated by any programmer. These programmers may choose to exploit graphics and interactive displays available in the program library developed and maintained by CERN (the Center for European Nuclear Research). This paper outlines the use of graphics and interactive data display features of the CERN program library, developed for visualizing simulated data events in particle detectors. One example uses GEANT, CERN's Monte Carlo modeling program, to simulate 300 MeV/c protons incident on a silicon slab. Display packages for GEANT are ...
Reflection HighEnergy ElectronDiffraction Study Of Surface Disorder And Anomalous Expansion Of Pb(100), D. Tang, H. E. ElsayedAli
Reflection HighEnergy ElectronDiffraction Study Of Surface Disorder And Anomalous Expansion Of Pb(100), D. Tang, H. E. ElsayedAli
Electrical & Computer Engineering Faculty Publications
The temperaturedependent surface structural behavior of Pb(100) is studied using reflection highenergy electron diffraction. Anomalous surface expansion for temperatures between room temperature to about 500 K is observed. A high density of surface vacancies appears at temperatures above ~ 500 K. © 1994 The American Physical Society.
A Fringe Center Detection Technique Based On A SubPixel Resolution, And Its Applications Using Sinusoidal Gratings, Ming Chang, Paul P. Lin, Wen Chih Tai
A Fringe Center Detection Technique Based On A SubPixel Resolution, And Its Applications Using Sinusoidal Gratings, Ming Chang, Paul P. Lin, Wen Chih Tai
Mechanical Engineering Faculty Publications
A common problem in optical profilometry is the accuracy in locating fringe centers. This paper presents an accurate fringe center detection technique based on subpixel resolution using the fringe projection method. An optimum reconstruction filter is developed which has low sensitivity to noise. In fringe center detection, computer simulation results of using onepixel and subpixel resolutions are compared. The detection technique is then applied to radius measurement of cylindrical objects and surface profile measurement of diffuse objects. The experimental results thus obtained through the proposed optimum reconstruction filter show significant improvement in measurement accuracy.
Connection Between Nmr And Electrical Conductivity In Glassy Chalcogenide Fast Ionic Conductors , KyungHan Kim
Connection Between Nmr And Electrical Conductivity In Glassy Chalcogenide Fast Ionic Conductors , KyungHan Kim
Retrospective Theses and Dissertations
Pulsed Nuclear Magnetic Resonance measurements and electric conductivity measurements have been performed in glassy fast ionic conductors, lithium thiogermanates ( xLi2S+(1x)GeS2) and lithium thioborates ( xLi2S+(1x)B2S3) in order to investigate the microscopic mechanism of ion dynamics. Both 7Li nuclear spin lattice relaxation rate (NSLR) versus temperature at several resonance frequencies (4 MHz to 135 MHz) and conductivity, [sigma]([omega]) versus temperature, in the frequency range from 1 Hz to 4 MHz have been measured. The 7Li NSLR show BPPtype behavior with strong asymmetry of the bell shaped curve on the two sides of the maximum. A sizable dependence ...
A ClosedForm Integration Method For StateSpace TimeDomain Analysis Of Electronic Circuits And Systems , Bruce Alan Alspaugh
A ClosedForm Integration Method For StateSpace TimeDomain Analysis Of Electronic Circuits And Systems , Bruce Alan Alspaugh
Retrospective Theses and Dissertations
While most traditional circuit simulation programs such as SPICE rely upon numerical integration techniques to perform transient analysis, this dissertation presents an alternative approach that relies on closedform integration. Traditional numerical approaches offer no hope of finding an analytical solution, even if it is known that the solutions will be in a simple functional form. By using closedform methods, the computer can find the exact analytical solution to the network and completely avoid problems associated with numerical approximations, determining appropriate integration step sizes, stiff systems of differential equations, or accumulated global error. Computer run time is independent of the amount ...
Active Noise Control In A ThreeDimensional Space , Jihe Yang
Active Noise Control In A ThreeDimensional Space , Jihe Yang
Retrospective Theses and Dissertations
In this research, a new approach is presented for optimizing the performance of active noise control in threedimensional space. The work focuses on the critical role of determining the locations for secondary sources in active noise suppression. A systematic technique is proposed for estimating optimal locations of secondary sources on the boundary of a threedimensional domain for both local and global active control of harmonic sound fields. The theoretical foundation of this work is Huygen's principle. The indirect boundary element method (IBEM) which is a numerical implementation of Huygen's principle is employed as a basis for the numerical ...
Magnetization Studies Of Oxides Related To The High Temperature Cuprate Superconductors , Zhaorong Wang
Magnetization Studies Of Oxides Related To The High Temperature Cuprate Superconductors , Zhaorong Wang
Retrospective Theses and Dissertations
An Oxford Instruments Faraday magnetometer, capable of operating in the temperature range between 1.5 K and 1000 K, and magnetic field range between 0 T to 8 T, with a sensitivity of 3x10[superscript]8 cm[superscript]3G, was assembled and calibrated. The pumping station which supported this magnetometer was designed and built. Software for reducing the raw data and generating calibration files was written. The magnetic properties of several oxides related to the high temperature cuprate superconductors BaCuO[subscript]2+x, La[subscript]2CuO[subscript]4, Sr[subscript]2IrO[subscript]4, Sr[subscript]2RhO[subscript]4, Sr[subscript ...
Characterization And Analysis Of Viscoelastically Loaded Thin Film Piezoelectric Resonators Incorporated In An Oscillator Microsensing System , Ronald Patrick O'Toole
Characterization And Analysis Of Viscoelastically Loaded Thin Film Piezoelectric Resonators Incorporated In An Oscillator Microsensing System , Ronald Patrick O'Toole
Retrospective Theses and Dissertations
In the recent advancement of piezoelectric resonator technology, there has been a large growth in the application of these devices for chemical sensing. These sensors operate by detecting changes in their environment which perturb the electrical  acoustic operation and in turn can be harnessed by means of supporting electronics and signal processing to monitor various processes. Examples include remote environmental monitoring, chemical process control, and commercial gas phase detectors. In this dissertation, the chemical sensing theory and properties of piezoelectric resonators such as the bulkacoustic wave thinfilm resonator (TFR) and the quartz crystal microbalance (QCM) are developed. This analysis concentrates ...
SubMicron Scale Conduction Processes On Clean Surfaces , Kevin R. Kimberlin
SubMicron Scale Conduction Processes On Clean Surfaces , Kevin R. Kimberlin
Retrospective Theses and Dissertations
Fundamental electrical conductance measurement has been studied insitu in two dimensions in the Ag/Si(111) system as a function of the incident adatom flux rate with a four probe technique. A conductance study in a three dimensional conical structure was also carried out with field emission techniques. Field emission is now well established and has been used in this case to characterize a novel geometry for use in flat panel displays to replace cathode ray tube monitors. For the two dimensional study on Ag/Si(111), the origin of conduction is still unclear, as both transport by means of ...
Models For Water Outgassing From Metal Surfaces, Minxu Li
Models For Water Outgassing From Metal Surfaces, Minxu Li
Dissertations, Theses, and Masters Projects
In this study, the outgassing rate from an electropolished stainless steel surface following exposures to H{dollar}\sb2{dollar}O vapor under various conditions was measured. The results of the experiments showed that the outgassing rate is proportional to {dollar}p\sb0\sp{lcub}n{rcub}{dollar}, where {dollar}p\sb0{dollar} is the H{dollar}\sb2{dollar}O exposure pressure and n is about 0.25. The outgassing rate is not as strongly dependent on the system temperature as one would expect if the temperature is kept the same during exposure and pumpdown. The outgassing rate is also a ...
Development Of Strength Theories For Random Fiber Composites, Victor Giurgiutiu
Development Of Strength Theories For Random Fiber Composites, Victor Giurgiutiu
Faculty Publications
A ressessment of existing theories for calculating the strength of random and quasirandom fiber composites is presented. Fundamental aspects regarding the physical model, macromechanics analysis, fiber distribution functions, generalized failure criterion, and progressive versus sudden failure models are covered first. Progressive ductile failure, progressive brittle failure, and sudden brittle failure are treated in detail. In each case, the original theory is briefly reviewed, and then its extensions accompanied by numerical examples are presented. Several limitations originally imposed by Hahn, such as the monotonically nonincreasing requirement on the failure strain curve, are lifted and the mathematical formulations are generalized. Some common ...
Several Considerations Regarding The Variable Length Blade Rotor, Bogdan Popescu, Victor Giurgiutiu
Several Considerations Regarding The Variable Length Blade Rotor, Bogdan Popescu, Victor Giurgiutiu
Faculty Publications
No abstract provided.
Multigrid Acceleration Of TimeDependent Solutions Of NavierStokes Equations, Sarafa Oladele Ibraheem
Multigrid Acceleration Of TimeDependent Solutions Of NavierStokes Equations, Sarafa Oladele Ibraheem
Mechanical & Aerospace Engineering Theses & Dissertations
Recent progress in Computational Fluid Dynamics is encouraging scientists to look at fine details of flow physics of problems in which natural unsteady phenomena have hitherto been neglected. The acceleration methods that have proven very successful in steady state computations can be explored for time dependent computations. In this work, an efficient multigrid methods is developed to solve the timedependent Euler and NavierStokes equations. The BeamWarming ADI method is used as the base algorithm for time stepping calculations. Application of the developed algorithm proved very efficient in selected steady and unsteady test problems. For instance, the inherent unsteadiness present in ...