Masahiko Hirao

Bio: Masahiko Hirao is an academic researcher from Osaka University. The author has contributed to research in topics: Electromagnetic acoustic transducer & Resonance. The author has an hindex of 35, co-authored 211 publications receiving 4292 citations. Previous affiliations of Masahiko Hirao include Ebara Corporation.

EMATs for Science and Industry: Noncontacting Ultrasonic Measurements

Abstract: Preface. Introduction: Noncontact Ultrasonic Measurements. Brief Historical Sketch of EMAT. Electromagnetic Acoustic Resonance - EMAR. Part I: Development of EMAT Techniques. 1: Coupling Mechanism. 1.1. Background. 1.2. Generation Mechanism. 1.3. Receiving Mechanisms. 1.4. Comparison with Measurements. 2 : Available EMATS. 2.1. Bulk-Wave EMATs. 2.2. Longitudinal-Guided-Wave EMAT for Wires and Pipes. 2.3. PPM EMAT. 2.4. Meander-Line Coil SH-Wave EMAT. 2.5. SH-Wave EMAT for Chirp Pulse Compression. 2.6. Axial-Shear-Wave EMAT. 2.7. SH-Wave EMAT for Resonance in Bolt Head. 2.8. Rayleigh-Wave EMAT. 2.9. Line-Focusing EMAT. 2.10. Trapped-Torsional-Mode EMAT. 2.11. EMATs for High Temperature Measurements. 3: Brief Instruction To Build EMATs. 3.1. Coil. 3.2. Magnets. 3.3. Impedance Matching. Part II: Resonance Spectroscopy with EMATs -EMAR-. 4: Principles of EMAR for Spectral Response. 4.1. Through-Thickness Resonance. 4.2. Spectroscopy with Analog Superheterodyne Processing. 4.3. Determination of Resonance Frequency and Phase Angle. 5: Free-Decay Measurement For Attenuation And Internal Friction. 5.1. Difficulty of Attenuation Measurement. 5.2. Isolation of Ultrasonic Attenuation. 5.3. Measurement of Attenuation Coefficient. 5.4. Correction for Diffraction Loss. 5.5. Comparison with Conventional Technique. Part III: Physical-Acoustics Studies. 6: In-Situ Monitoring Of Dislocation Mobility. 6.1. Dislocation-Damping Model for Low Frequencies. 6.2. Elasto-Plastic Deformation in Copper. 6.3. Point-Defect Diffusion toward Dislocations in Deformed Aluminum. 6.4. Dislocation Damping after Elastic Deformation in Al-Zn Alloy. 6.5. Recovery and Recrystallization in Aluminum. 7: Elastic Constants and Internal Friction of Advanced Materials. 7.1. Mode Control in Resonance Ultrasound Spectroscopy by EMAR. 7.2. Inverse Calculation for Cij and Qij-1. 7.3. Monocrystal Copper. 7.4. Metal-Matrix Composites (SiCf/Ti-6Al-4V). 7.5. Lotus-Type Porous Copper. 7.6. Ni-Base Superalloys. 7.7. Thin Films. 7.8. Piezoelectric Material (Langasite: La3Ga5SiO14). 8: Nonlinear Acoustics. Part IV: Industrial Applications. 9: On-Line Texture Monitoring Of Steel Sheets. 9.1. Texture of Polycrystalline Metals. 9.2. Mathematical Expressions of Texture and Velocity Anisotropy. 9.3. Relation between ODCs and r-Values. 9.4. On-Line Monitoring with Magnetostrictive-Type EMATs. 10: Acoustoelastic Stress Measurements. 10.1. Nonlinear Elasticity. 10.2. Acoustoelastic Response of Solids. 10.3. Birefringence Acoustoelasticity. 10.4. Practical Stress Measurements with EMAR. 10.5. Monitoring Bolt Axial Stress. 11: Measurements On High-Temperature Steels. 11.1. Velocity Variation at High Temperatures. 11.2. Solidification-Shell Thickness of Continuous Casting S

An SH-wave EMAT technique for gas pipeline inspection

Abstract: An EMAT technique has been developed to detect corrosion defects on the outer surfaces of steel pipelines. A periodic-permanent-magnet (PPM) EMAT is placed inside the pipe, which generates and receives the SH guided waves traveling in the circumferential direction with the axial polarization. Wheels installed on the PPM-EMAT facilitate the linear movement in the axial direction and are useful for a quick inspection. At each point in scanning, the amplitude and phase shift of the round-trip signals in the SH0 and SH1 modes are measured using a superheterodyne phase-sensitive detector. They respond uniquely to surface defects and provide relevant information for locating axial positions of defects and evaluating the depth. The amplitude and phase shift of the SH1 mode are more sensitive to the presence of the defects than those of the SH0 mode. This technique is useful even if the protective resin coating is tightly glued on the pipes and lowered the signal intensity.

Complete mode identification for resonance ultrasound spectroscopy.

Abstract: This study is devoted to deducing exact elastic constants of an anisotropic solid material without using any advance information on the elastic constants by incorporating a displacement-distribution measurement into resonant ultrasound spectroscopy (RUS). The usual RUS method measures free-vibration resonance frequencies of a solid and compares them with calculations to find the most suitable set of elastic constants by an inverse calculation. This comparison requires mode identification for the measured resonance frequencies, which has been difficult and never been free from ambiguity. This study then adopts a laser-Doppler interferometer to measure the displacement-distribution patterns on a surface of the vibrating specimen mounted on pinducers; comparison of the measured displacement distributions with those computed permits us to correctly identify the measured resonance frequencies, leading to unmistakable determination of elastic constants. Because the displacement patterns are hardly affected by the elastic constants, an exact answer is surely obtained even when unreasonable elastic constants are used as initial guesses at the beginning of the inverse calculation. The usefulness of the present technique is demonstrated with an aluminum alloy and a langasite crystal.

Contactless mode-selective resonance ultrasound spectroscopy: Electromagnetic acoustic resonance

Abstract: A noncontacting resonant-ultrasound-spectroscopy (RUS) method for measuring elastic constants and internal friction of conducting materials is described, and applied to monocrystalline copper. This method is called electromagnetic acoustic resonance (EMAR). Contactless acoustic coupling is achieved by energy transduction between the electromagnetic field and the ultrasonic vibrations. A solenoidal coil and static magnetic field induce Lorentz forces on specimen surfaces without using a coupling agent. By changing the field direction, a particular set of vibration modes can be selectively excited and detected, an advantage in identifying the vibration modes of the observed resonance peaks. Contactless coupling allows the measure of intrinsic internal friction free from energy loss associated with contact coupling. The elastic constants and internal friction measured by EMAR are compared with those by the usual RUS method for a rectangular-parallelepiped copper monocrystal. Both methods yielded the same ela...

Recent developments in stainless steels

Abstract: This article presents an overview of the developments in stainless steels made since the 1990s. Some of the new applications that involve the use of stainless steel are also introduced. A brief introduction to the various classes of stainless steels, their precipitate phases and the status quo of their production around the globe is given first. The advances in a variety of subject areas that have been made recently will then be presented. These recent advances include (1) new findings on the various precipitate phases (the new J phase, new orientation relationships, new phase diagram for the Fe–Cr system, etc.); (2) new suggestions for the prevention/mitigation of the different problems and new methods for their detection/measurement and (3) new techniques for surface/bulk property enhancement (such as laser shot peening, grain boundary engineering and grain refinement). Recent developments in topics like phase prediction, stacking fault energy, superplasticity, metadynamic recrystallisation and the calculation of mechanical properties are introduced, too. In the end of this article, several new applications that involve the use of stainless steels are presented. Some of these are the use of austenitic stainless steels for signature authentication (magnetic recording), the utilisation of the cryogenic magnetic transition of the sigma phase for hot spot detection (the Sigmaplugs), the new Pt-enhanced radiopaque stainless steel (PERSS) coronary stents and stainless steel stents that may be used for magnetic drug targeting. Besides recent developments in conventional stainless steels, those in the high-nitrogen, low-Ni (or Ni-free) varieties are also introduced. These recent developments include new methods for attaining very high nitrogen contents, new guidelines for alloy design, the merits/demerits associated with high nitrogen contents, etc.

Electrochemical Sensors and Biosensors

Abstract: This review covers advances in electrochemical and biochemical sensor development and usage during 2010 and 2011 In choosing scholarly articles to contribute to this review, special emphasis was placed on work published in the areas of reference electrodes, potentiometric sensors, voltammetric sensors, amperometric sensors, biosensors, immunosensors, and mass sensors In the past two years there have been a number of important papers, that do not fall into the general subsections contained within the larger sections Such novel advances are very important for the field of electrochemical sensors as they open up new avenues and methods for future research Each section above contains a subsection titled “Other Papers of Interest” that includes such articles and describes their importance to the field in general For example, while most electrochemical techniques for sensing analytes of interest are based on the changes in potential or current, Shan et al1 have developed a completely novel method for performing electrochemical measurements In their work, they report a method for imaging local electrochemical current using the optical signal of the electrode surface generated from a surface plasmon resonance (SPR) The electrochemical current image is based on the fact that the current density can be easily calculated from the local SPR signal The authors demonstrated this concept by imaging traces of TNT on a fingerprint on a gold substrate Full articles and reviews were primarily amassed by searching the SciFinder Scholar and ISI Web of Knowledge Additional articles were found through alternate databases or by perusing analytical journals for pertinent publications Due to the reference limitation, only publications written in English were considered for inclusion Obviously, there have been more published accounts of groundbreaking work with electrochemical and biochemical sensors than those covered here This review is a small sampling of the available literature and not intended to cover every advance of the past two years The literature chosen focuses on new trends in materials, techniques, and clinically relevant applications of novel sensors To ensure proper coverage of these trends, theoretical publications and applications of previously reported sensor development were excluded We want to remind our readers that this review is not intended to provide comprehensive coverage of electrochemical sensor development, but rather to provide a glimpse of the available depth of knowledge published in the past two years This review is meant to focus on novel methods and materials, with a particular focus on the increasing use of graphene sheets for sensor material development For readers seeking more information on the general principles behind electrochemical sensors and electrochemical methods, we recommend other sources with a broader scope2, 3 Electrochemical sensor research is continually providing new insights into a variety of fields and providing a breadth of relevant literature that is worthy of inclusion in this review Unfortunately, it is impossible to cover each publication and unintentional oversights are inevitable We sincerely apologize to the authors of electrochemical and biochemical sensor publications that were inadvertently overlooked