Different long-term acoustic memory and magnetoacoustic effects were observed in magnetostrictive materials at their inductive excitation by radiofrequency (RF) and magnetic pulses using pulsed NMR and magnetic video-pulse excitation techniques. Along it the stimulated domain-acoustic echo (DAE), possessing a long-term acoustic memory was inductively excited by three RF pulses in magnetite and magnetoelectric ferrite-piezoelectric layered composites using pulsed NMR technique with inductive and...
Topics: Domain-acoustic Echo, Magnetoacoustics, Magnetostriction, Magnetoelectrics, Pulsed NMR, Magnetic...
Different long-term acoustic memory and magnetoacoustic effects were observed in magnetostrictive materials at their inductive excitation by radiofrequency (RF) and magnetic pulses using pulsed NMR and magnetic video-pulse excitation techniques. Along it the stimulated domain-acoustic echo (DAE), possessing a long-term acoustic memory was inductively excited by three RF pulses in magnetite and magnetoelectric ferrite-piezoelectric layered composites using pulsed NMR technique with inductive...
Topics: Domain-acoustic Echo, Magnetoacoustics, Magnetostriction, Magnetoelectrics, Pulsed NMR, Magnetic...
186
186
Jun 11, 2011
06/11
by
Spirkovska, Lill
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Automation in the aviation domain has been increasing for the past two decades. Pilot reaction to automation varies from highly favorable to highly critical depending on both the pilot's background and how effectively the automation is implemented. We describe a user-centered approach for automation that considers the pilot's tasks and his needs related to accomplishing those tasks. Further, we augment rather than replace how the pilot currently fulfills his goals, relying on redundant displays...
Topics: MAGNETOACOUSTICS, FINITE ELEMENT METHOD, MATHEMATICAL MODELS, RAIL TRANSPORTATION, WHEELS,...
252
252
Jun 9, 2011
06/11
by
Cahoon, Donald R.; Stocks, Brian J.; Levine, Joel S.; Cofer, Wesley R., III; O'Neill, Katherine P
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Savannas consist of a continuous layer of grass interspersed with scattered trees or shrubs, and cover approx. 10 million square kilometers of tropical Africa. African savanna fires, almost all resulting from human activities, may produce as much as a third of the total global emissions from biomass burning. Little is known, however, about the frequency and location of these fires, and the area burned each year. Emissions from African savanna burning are known to be transported over the...
Topics: MAGNETOACOUSTICS, EMISSION SPECTRA, FERROMAGNETIC MATERIALS, TENSILE STRESS, MICROSTRUCTURE,...
Recent studies have shown that strong correlations are observed between the low frequencies (1-10 Hz) of quasiperiodic oscillations (QPOs) and the spectral power law index of several Black Hole (BH) candidate sources, in low hard states, steep power-law (soft) states and in transition between these states. The observations indicate that the X-ray spectrum of such state (phases) show the presence of a power-law component and are sometimes related to simultaneous radio emission indicated the...
Topics: NASA Technical Reports Server (NTRS), OSCILLATIONS, FREQUENCIES, BLACK HOLES (ASTRONOMY), RADIO...
The results of a calculation of the attenuation of ultrasonic waves in a metal when a dc magnetic field is present in a direction parallel to the polarization direction of a sound wave is de scribed. A principal part of the report includes tables of use to anyone interested in attenuation calculations. Graphical results for the case in question are included.
Topics: DTIC Archive, Grubin, Harold L, POLYTECHNIC INST OF BROOKLYN NY, *ACOUSTIC WAVES, *ULTRASONIC...
This paper describes a series of numerical simulations of field reversal in the Reversed Field Pinch, using an incompressible MHD model and a reference set of plasma conditions. Field reversal and maintenance are observed although at values of the pinch parameter O larger than in experiment. This discrepancy is shown to arise largely from the unrealistic resistivity profile in the reference conditions and may not be fundamental. Qualitative agreement with experiment is demonstrated in several...
Topics: DTIC Archive, Kirby,P, UKAEA CULHAM LAB ABINGDON (ENGLAND), *PINCH EFFECT, *MAGNETOHYDRODYNAMICS,...
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227
Jun 9, 2011
06/11
by
Huang, J.; Minnis, P.; Lin, B.; Yi, Y.; Ayers, J. K.; Khaiyer, M. M.; Arduini, R.; Fan, T.-
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A more rigorous multilayered cloud retrieval system has been developed to improve the determination of high cloud properties in multilayered clouds. The MCRS attempts a more realistic interpretation of the radiance field than earlier methods because it explicitly resolves the radiative transfer that would produce the observed radiances. A two-layer cloud model was used to simulate multilayered cloud radiative characteristics. Despite the use of a simplified two-layer cloud reflectance...
Topics: ASYMMETRY, MAGNETIC FIELDS, MAGNETIC DOMAINS, RESIDUAL STRESS, FERROMAGNETISM, HEAT TREATMENT,...
It is shown that the entire Fermi surface can be mapped by using geometric resonances in the sound attenuation in tilted magnetic fields and the drift velocity of the carriers along the magnetic field simultaneously determined. The general features of the phenomena considered do not prove dependent on the particular models used in our calculations. In addition to the results specifically pertaining to tilted fields, when the assumptions of equal effective masses and relaxation times are dropped...
Topics: DTIC Archive, SPECTOR, HAROLD N, CHICAGO UNIV IL, *ACOUSTIC ATTENUATION, *SOLID STATE PHYSICS,...
This effort produced a novel image-processing algorithm which has allowed successful identification and accurate track of solar plumes in Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) data and, moreover, enabled the first direct measurements of transverse waves in solar polar plumes. This image-processing technique has allowed direct measurement of the transverse displacements, periods and velocity-amplitudes of 596 distinct oscillations in the 171 channel (over a 4 hour...
Topics: DTIC Archive, NORTHUMBRIA UNIV NEWCASTLE UPON TYNE (UNITED KINGDOM), *SOLAR WIND, ALGORITHMS,...
The magnetoacoustic measurement technique has been used successfully for residual stress measurements in laboratory samples. However, when used to field test samples with complex geometries, such as railroad wheels, the sensitivity of the method declines dramatically. It has been suggested that the decrease in performance may be due, in part, to an insufficient or nonuniform magnetic induction in the test sample. The purpose of this paper is to optimize the test conditions by using finite...
Topics: NASA Technical Reports Server (NTRS), MAGNETOACOUSTICS, FINITE ELEMENT METHOD, MATHEMATICAL MODELS,...
One of the critical elements related to the practicality of any NDE technique is its reproducibility under nominally the same inspection conditions. The results of certain test methodologies, however, are not always repeatable and understanding the origin of the irreproducibility is often as critical as obtaining reproducible results. One example is the characterization of residual stress in structural ferromagnets using the magnetoacoustic (MAC) method. Although it has not been widely...
Topics: NASA Technical Reports Server (NTRS), NONDESTRUCTIVE TESTS, MAGNETIC MEASUREMENT, MAGNETOACOUSTICS,...
This grant has supported a number of different activities related to the primary Air Force grant F49620-95- 1-0008, Environmental Conditions Responsible for Solar Activity. Under this AASERT grant, students Frankie Liu and Aaron Birch approached several problems relevant to solar activity. Liu calculated the coronal magnetic field from vector magnetograph data when the field is assumed to be force-free but not current-free. Liu solved the problem by the method of simulated annealing. This...
Topics: DTIC Archive, Radoski, Henry, STANFORD UNIV CA CENTER FOR SPACE SCIENCE AND ASTROPHYSICS, *MAGNETIC...
Two types of ferromagnets, pure iron and steel with varying geometry and microstructural properties, were prepared for the present study of magnetoacoustic emission (MAE). The purpose was to separate the effects of structural property variations from changes caused by differences in the sample geometry. The position and shape of the leading MAE sub-burst and its variation among the samples are explained by magnetic anisotropy and the results of numerical simulations which utilized the concept...
Topics: NASA Technical Reports Server (NTRS), MAGNETOACOUSTICS, ANISOTROPY, NUMERICAL ANALYSIS,...
A new inspection technology called magneto-optic/eddy current imaging was investigated. The magneto-optic imager makes readily visible irregularities and inconsistencies in airframe components. Other research observed in electromagnetics included (1) disbond detection via resonant modal analysis; (2) AC magnetic field frequency dependence of magnetoacoustic emission; and (3) multi-view magneto-optic imaging. Research observed in the thermal group included (1) thermographic detection and...
Topics: NASA Technical Reports Server (NTRS), EDDY CURRENTS, ELECTROMAGNETISM, IMAGING TECHNIQUES, INFRARED...
Volume I of the Proceedings of the 2000 Physical Acoustics Summer School contains verbatim transcriptions of the lectures given at the summer school. Volume II of these proceedings contains copies of the transparencies used by the lecturers and Volume III contains background materials that were sent to student and discussion leader participants prior to the summer school.
Topics: DTIC Archive, Bass, Henry E, NATIONAL CENTER FOR PHYSICAL ACOUSTICS UNIVERSITY MS, *ACOUSTICS,...
Volume I of the Proceedings of the 2000 Physical Acoustics Summer School contains verbatim transcriptions of the lectures given at the summer school. Volume II of these proceedings contains copies of the transparencies used by the lecturers and Volume III contains background materials that were sent to student and discussion leader participants prior to the summer school.
Topics: DTIC Archive, Bass, Henry E, NATIONAL CENTER FOR PHYSICAL ACOUSTICS UNIVERSITY MS, *ACOUSTICS,...
Our recent study has proved a strong correlation between the low-frequency AC applied magnetic field amplitude dependence of the asymmetry of the magnetoacoustic emission (MAE) burst and the strength of the domain wall-defect interaction in iron-base ferromagnets. For the present study the AC magnetic field frequency dependence of the asymmetry has been investigated in the range of 1 to 200 Hz. When represented by the third moment of the rectified acoustic emission pulses, the asymmetry becomes...
Topics: NASA Technical Reports Server (NTRS), ALTERNATING CURRENT, MAGNETOACOUSTICS, FIELD EMISSION,...
No abstract available
Topics: NASA Technical Reports Server (NTRS), FERROMAGNETIC MATERIALS, MAGNETOSTRICTION, MAGNETOACOUSTICS,...
This article reviews magnetomechanical acoustic emission (MAE) that can be used in developing nondestructive testing techniques for residual stress measurements and microstructural characterization. Effects of metallurgical and magnetic parameters on MAE are considered drawing from basic studies on nickel and iron as well as from applied research on rail and wheel steels. Some of the observed features of MAE can be explained in terms of the domain theory. Practical applications require...
Topics: DTIC Archive, Ono, Kanji, CALIFORNIA UNIV LOS ANGELES DEPT OF MATERIALS SCIENCE AND ENGINEERING,...
Contents: Fundamentals of Magnetostriction; Technology of Magnetostrictive Transducer Related to Material Requirements; Single Crystal Saturation Magnetostriction; Magnetostrictive Material Requirements for Sonar Transducers; Processing Control of Magnetic Properties for Magnetostrictive Transducer Applications; General Discussion of Scientific Opportunities in Magnetostrictive Material for Transducers.
Topics: DTIC Archive, Gardner,Frank S, OFFICE OF NAVAL RESEARCH BOSTON MASS, *MAGNETOSTRICTION,...
The purpose of this survey is to create an accurate residual magnetic contour map of the Magnetic Observatory area at Stennis Space Center. Measurements were completed covering the observatory grounds. A map of the magnetic residuals is presented.
Topics: DTIC Archive, Estes, C R, NAVAL OCEANOGRAPHIC AND ATMOSPHERIC RESEARCH LAB STENNIS SPACE CENTER MS,...
The Fermi surface of indium was investigated using the Doppler-shifted acoustic cyclotron resonance method. The measurements are sensitive to small changes in the shape of the Fermi surface and, hence, are a good measure of the deviations of the Fermi surface from the free-electron model. The attenuation of short pulses of longitudinal sound, with a frequency between 100 MHz and 300 MHz, in single crystal indium was measured in the presence of a varying magnetic field. Values of the magnetic...
Topics: DTIC Archive, Hayden,Stephen C, PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB,...
This study seeks to calculate the generation and propagation of Magneto-Acoustic Gravity (M.A.G.) waves in the solar atmosphere and their effect on the heating of the chromosphere and corona. A computer program has been written, which is capable of integrating the equations of motion of such waves, which are inherently three-dimensional. To simplify the equations, without seriously distorting the nature of the motions, we impose a fixed horizontal modal structure consisting of 6 waves...
Topics: DTIC Archive, Stein,R f, BRANDEIS UNIV WALTHAM MASS DEPT OF PHYSICS, *SOLAR CORONA, *SOLAR...
The primary purpose of this program was to use nonlinear techniques to study electron dynamics and kinetics in semiconductors. Possible applications of nonlinear interactions were also considered. These investigations have combined theory and experiment. The statement of work for the contract included the following tasks: (A) Study impurity dynamics and electron delocalization in Ge and Si; (B) Generate infrared radiation via coherent excitation of collective modes; (C) Observe and Study...
Topics: DTIC Archive, Wolff,P A, MASSACHUSETTS INST OF TECH CAMBRIDGE, *Semiconductors, *Nonlinear systems,...
197
197
May 28, 2011
05/11
by
Wong, Sun; Prather, Michael J.; Rind, David H
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The 6-year wind archives from the Goddard Institute for Space Studies/Global Climate-Middle Atmosphere Model (GISS/GCMAM) were in- put to the GISS/Harvard/Irvine Chemical Transport Model (G/H/I CTM) to study the seasonal and interannual variability of the budgets and distributions of nitrous oxide (N2O) and trichlorofluoromethane (CCl3F), with the corresponding chemical loss frequencies recycled and boundary conditions kept unchanged from year to year. The effects of ozone feedback and...
Topics: INTERPLANETARY MAGNETIC FIELDS, LONGITUDE, ANGLES (GEOMETRY), MAGNETOHYDRODYNAMICS,...
Volume I of the Proceedings of the 2000 Physical Acoustics Summer School contains verbatim transcriptions of the lectures given at the summer school. Volume II of these proceedings contains copies of the transparencies used by the lecturers and Volume III contains background materials that were sent to student and discussion leader participants prior to the summer school.
Topics: DTIC Archive, Bass, Henry E, NATIONAL CENTER FOR PHYSICAL ACOUSTICS UNIVERSITY MS, *ACOUSTICS,...
240
240
Aug 2, 2010
08/10
by
Plaza-Rosado, Heribert
texts
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Thermal neutron activation analyses were carried out for various space systems components to determine gamma radiation dose rates and food radiation contamination levels. The space systems components selected were those for which previous radiation studies existed. These include manned space vehicle radiation shielding, liquid hydrogen propellant tanks for a Mars mission, and a food supply used as space vehicle radiation shielding. The computational method used is based on the fast neutron...
Topics: FAILURE ANALYSIS, CONTRACTION, COOLING, DISTORTION, HEAT TREATMENT, MAGNETOACOUSTICS, RIMS,...
The invention is a method and apparatus for characterizing residual uniaxial stress in a ferromagnetic test member by distinguishing between residual stresses resulting from positive (tension) forces and negative (compression) forces by using the distinct and known magnetoacoustic (MAC) and a magnetoacoustic emission (MAE) measurement circuit means. A switch permits the selective operation of the respective circuit means.
Topics: NASA Technical Reports Server (NTRS), CHARACTERIZATION, FERROMAGNETIC MATERIALS, MAGNETOACOUSTICS,...
An acoustic wave propagating in a conductive medium in the presence of a magnetic field will induce electric potential fields and currents, and, associated with the electric currents, secondary magnetic fields. This interaction is of interest because it occurs in acoustic propagation through sea water in the presence of the earth's magnetic field, and at ultra-low frequency (ULF), acoustic waves should be detectable. A Green's function solution in an infinite medium is developed, with an...
Topics: DTIC Archive, Klaus,Robert Franz, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *MAGNETIC INDUCTION,...
An extensive study of magnetoacoustic emission (MAE) properties has been performed over the past several years. As a result, the dependence of the spectral characteristics of MAE on certain microstructural variations and uniaxially applied stress in a particular type of low carbon steel are now well known. The embrittlement-causing concentration of certain atomic species, e. g., tin, sulphur, phosphorous etc., at the grain boundaries of this steel creates strong potential barriers resisting the...
Topics: NASA Technical Reports Server (NTRS), MAGNETOACOUSTICS, EMISSION SPECTRA, FERROMAGNETIC MATERIALS,...
We present a method for solving plasma magnetohydrodynamic (MHD) problems arising from the interaction of plasmas with magnetic fields in stellar atmospheres. Our approach, in contrast to previous methods, is not based on solving equations for the magnetic field and plasma velocity but rather studies the evolution of the electric current and density (and the related gas pressure). We have applied the method to several studies involving linearized departures from static, current-free equilibria....
Topics: NASA Technical Reports Server (NTRS), FREE ENERGY, MAGNETIC FIELD CONFIGURATIONS,...
In this report, the analysis and programming for various problems in the field of Electromagnetic propagation and antenna design are considered. The scope of our work extended into a variety of technical areas. Among the technical areas are: Magneto-acoustic surface waves, Signal analysis, Polar VLF propagation, Ionospheric pulse reflections, Detection and tracking of targets, and Antenna Design. (Author)
Topics: DTIC Archive, O'Brien ,John, ARCON CORP WALTHAM MA, *ELECTROMAGNETIC WAVE PROPAGATION, *ANTENNA...
It has been well known that the pattern of the magnetoacoustic emission (MAE) burst observed during the sweep over one half-cycle of the hysteresis loop becomes asymmetric depending on the strength of the magnetic domain wall-defect interaction and the state of residual stresses in a ferromagnet. The ascending asymmetry due to the former has been observed at a very low frequency (.7 Hz) of applied AC magnetic field at a given amplitude. The descending asymmetry due to uniaxial compressive...
Topics: NASA Technical Reports Server (NTRS), ASYMMETRY, MAGNETOACOUSTICS, CHARACTERIZATION, ACOUSTIC...
A new ultrasonic approach for monitoring the anelastic behavior of metals and alloys was presented. The approach poses some problems related to separating the temperature dependence of the anelastic phenomena from the natural wave velocity s susceptibility to temperature changes. However, these effects can be distinguished and separated without much difficulty. Due to its high sensitivity to microstructural changes, the new technique will be quite valuable when used in conjunction with strain...
Topics: NASA Technical Reports Server (NTRS), ANELASTICITY, ULTRASONICS, METALS, ALLOYS, MAGNETOACOUSTICS,...
A parallel shock wave structure is modelled as a region of interpenetrating streams of cold unshocked and hot shocked ions. Our liner dispersion theory predicts that unstable whistlers can stand and therefore grow to large amplitude at the leading edge of weak and intermediate strength shocks. Magnetosonic instabilities and their role in the structure of perpendicular shock waves were also studied. Since these instabilities are not stationary in the shock layer, they cannot play a principal...
Topics: DTIC Archive, Cipolla,John W, Golden,Kenneth I, Pavel,Arthur L, Silevitch,Michael B, NORTHEASTERN...
A method and apparatus for testing steel components for temperature embrittlement uses magneto-acoustic emission to nondestructively evaluate the component are presented. Acoustic emission signals occur more frequently at higher levels in embrittled components. A pair of electromagnets are used to create magnetic induction in the test component. Magneto-acoustic emission signals may be generated by applying an AC current to the electromagnets. The acoustic emission signals are analyzed to...
Topics: NASA Technical Reports Server (NTRS), ELECTROMAGNETS, EMBRITTLEMENT, MAGNETIC INDUCTION, MAGNETIC...
We have studied the heating of the solar chromosphere and transition region by acoustic waves. We find they are incapable of transporting sufficient energy through the chromosphere to heat the transition region and corona. We are developing a radiative fluid dynamic computer code to study acoustic heating of the chromosphere and the effect of acoustic waves on line profiles. In order to study heating by other types of wave motions we have analyzed the wave vector surface of the...
Topics: DTIC Archive, Stein,Robert F, MICHIGAN STATE UNIV EAST LANSING DEPT OF ASTRONOMY AND ASTROPHYSICS,...
Residual stresses in finished parts have often been regarded as factors contributing to premature part failure and geometric distortions. Currently, residual stresses in welded structures and railroad components are being investigated. High residual stresses formed in welded structures due primarily to the differential contractions of the weld material as it cools and solidifies can have a profound effect on the surface performance of the structure. In railroad wheels, repeated use of the...
Topics: NASA Technical Reports Server (NTRS), FAILURE ANALYSIS, FERROMAGNETIC MATERIALS, INCONEL...
The Voyager spacecraft (V1 and V2) observed electrons of 6-14 MeV in the heliosheath which showed several incidences of flux variation relative to a background of gradually increasing flux with distance from the Sun. The increasing flux of background electrons is thought to result from inward radial diffusion. We compare the temporal electron flux variation with dynamical phenomena in the heliosheath that are obtained from our MHD simulations. Because our simulation is based on V2 observed...
Topics: NASA Technical Reports Server (NTRS), HELIOSPHERE, INTERPLANETARY SHOCK WAVES,...
Magnetic measurements have been made above ocean waves from a stable platform at sea. The results are consistent with the theory of magnetic fields associated with ocean waves. The theory offers the potential to reduce or eliminate ocean wave noise in MAD (Magnetic Anomaly Detection).
Topics: DTIC Archive, Ochadlick, Andrew R., Jr, NAVAL AIR DEVELOPMENT CENTER WARMINSTER PA SENSORS AND...
Magnetoacoustic emission (MAE) is a phenomenon where acoustic noise is generated due to the motion of non-180 magnetic domain walls in a ferromagnet with non-zero magnetostrictive constants. MAE has been studied extensively for many years and has even been applied as an NDE tool for characterizing the heat treatment of high-yield low carbon steels. A complete theory which fully accounts for the magnetoacoustic response, however, has not yet emerged. The motion of the domain walls appears to be...
Topics: NASA Technical Reports Server (NTRS), MAGNETOACOUSTICS, PROBABILITY THEORY, COMPUTERIZED...
A hydroacoustic projector has been constructed with a ferrofluid as the magneto-acoustic transduction material. It has a toroidal shape; a dc magnetic bias field magnetizes the particles, and an ac field causes bulk movement of the fluid inside the toroid, as contrasted with magnetostriction. The construction of a prototype projector is described. As predicted by theory, the frequency of the acoustic field without bias field is predominantly double that of the exciting frequency; with bias...
Topics: DTIC Archive, Ptak,Mark S, FLORIDA INST OF TECH MELBOURNE, *ACOUSTIC MEASUREMENT, *FLEXURAL...
A list of the interplanetary (IP) shocks observed by WIND from its launch (in November 1994) to May 1997 is presented. Forty two shocks were identified. The magnetohydrodynamic nature of the shocks is investigated, and the associated shock parameters and their uncertainties are accurately computed using a practical scheme which combines two techniques. These techniques are a combination of the "pre-averaged" magnetic-coplanarity, velocity-coplanarity, and the Abraham-Schrauner-mixed...
Topics: NASA Technical Reports Server (NTRS), INTERPLANETARY MAGNETIC FIELDS, MAGNETIC CLOUDS, SOLAR...
The irradiation effects of reactor vessel steels were studied by magneto-acoustic emission (MAE). MAE is a new method of non-destructive evaluation. It is generated primarily by domain wall motions during magnetization of ferromagnetic materials in the alternating magnetic field. Since MAE activity is sensitive to the microstructural changes, it is applied to determine the status of steel samples exposed to neutron irradiation. Two commercial steels, A302B plate and A533B weld, and two model...
Topics: DTIC Archive, Kwon, Oh-Yang, CALIFORNIA UNIV LOS ANGELES DEPT OF MATERIALS SCIENCE AND ENGINEERING,...
This investigation was aimed at studying acoustic emission for applications to residual stress measurements and for the evaluation of structural integrity of engineering structures. Effects of microstructure, composition and prior cold working on magnetomechanical acoustic emission(MAE) have been studied. Magnetization behavior, magnetostriction and Barkhausen noise are affected by stress as well as other parameters. These responses have been measured simultaneously in order to identify the...
Topics: DTIC Archive, Ono, Kanji, CALIFORNIA UNIV LOS ANGELES DEPT OF MATERIALS SCIENCE AND ENGINEERING,...