bluuebunny/crossref_metadata_2025 huggingface dataset:
Organic Light-Emitting Diodes Using Multifunctional Phosphorescent Dendrimers with Iridium-Complex Core and Charge-Transporting Dendrons
Authors: Tsuzuki Toshimitsu , Shirasawa Nobuhiko , Suzuki Toshiyasu , Tokito Shizuo
Published: July 2005

We report a novel class of light-emitting materials for use in organic light-emitting diodes (OLEDs): multifunctional phosphorescent dendrimers that have a phosphorescent core and dendrons based on charge-transporting building blocks. We synthesized first-generation and second-generation dendrimers consisting of a fac-tris(2-phenylpyridine)iridium [Ir(ppy)3] core and hole-transporting phenylcarbazole-based dendrons. Smooth amorphous films of these dendrimers were formed by spin-coating them from solutions. The OLEDs using the dendrimer exhibited bright green or yellowish-green emission from the Ir(ppy)3 core. The OLEDs using the film containing a mixture of the dendrimer and an electron-transporting material exhibited higher efficiency than those using the neat dendrimer film. The external quantum efficiency of OLEDs using the film containing a mixture of the first-generation dendrimer and an electron-transporting material was as high as 7.6%.
Study of Dipolar Association in Binary System Acetyl Acetone in Aliphatic Alcohols
Authors: Acharya Swaroop , Mishra Sarmistha , Mohanty Gouranga Charan
Published: July 2005

The dielectric constant (ε
m) of binary mixtures of acetylacetone (HAA) with aliphatic alcohols viz. 1-pentanol, 1-butanol, 1-propanol has been measured at temperature 303.16 K and frequency 455 kHz. The data of dielectric constant are used to compute mutual correlation factor (g

a
b
), excess molar polarization (ΔP) and excess free energy of mixing (ΔG

a
b
) to study the molecular interaction. The study reveals that interaction is maximum for HAA + pentanol system and microheterogeneous β-clusters with antiparallel orientation of dissimilar molecules predominate in it.
Green- and White-Light-Emitting Devices Made from Poly(9,9-dioctylfluorene) by Maskless Dye Diffusion Technique
Authors: Tada Kazuya , Onoda Mitsuyoshi
Published: July 2005

Tuning the emission color of polymer light-emitting devices (PLEDs) based on a conjugated polymer poly(9,9-dioctylfluorene) (PDOF) through the maskless dye diffusion technique has been studied. The introduction of a green-light-emitting dye, Coumarin 6, into PDOF through this technique results in green light emission from the PLEDs without notable alteration of the external quantum efficiency. On the other hand, the introduction of a red-light-emitting dye, Nile red, which generates pure red light in a poly(N-vinylcarbazole) matrix, results in a white light emission from the PLEDs with an external quantum efficiency smaller than the original device. The onset voltages of emission were almost doubled for both cases, suggesting that both dyes play a role of carrier trap in the polymer. For emission mechanisms, it was suggested that the former case be governed by the efficient energy transfer from PDOF to Coumarin 6 or the direct recombination in Coumarin 6, while the latter case may include exciplex formation.
Methods of Measuring Energy Conversion Efficiency in Dye-sensitized Solar Cells
Authors: Koide Naoki , Chiba Yasuo , Han Liyuan
Published: July 2005

The current–voltage characteristics of dye-sensitized solar cells (DSCs) were measured and compared with those of crystalline silicon solar cells. It was found that the energy conversion efficiency of DSCs is dependent on voltage sweep direction and sampling delay time (T
d). Measurement of the transient photocurrent revealed that this dependence is due to the longer time constant of DSCs. This dependence was also confirmed in a simulation of current–voltage curves based on an equivalent circuit model of DSCs. Analysis of the current–voltage characteristics of polymer-based bulk heterojunction solar cells (BHSCs) and simulated measurements showed that the longer time constant is due to slow movement of ions in the electrolyte. To improve accuracy, the I–V measurement should be carried out from short circuit to open circuit with T
d of 100 ms or longer.
Preparation of Carbazole Polymer Thin Films by Electron-Assisted Deposition of 3-(N-Carbazolyl)propyl Acrylate
Authors: Katsuki Kiyoi , Kawakami Akira , Ogino Kenji , Tanaka Kuniaki , Usui Hiroaki
Published: July 2005

Polymeric thin films having carbazole pendant groups were prepared by physical vapor deposition of 3-(N-carbazolyl)propyl acrylate (CPA). The conventional vacuum evaporation of CPA formed thin films that consist mainly of small molecules. The evaporated films had needlelike crystallites in the as-deposited state, and underwent severe coalescence upon annealing at 125°C. The deposition polymerization of CPA was achieved by initiating polymerization by electron irradiation onto the monomer vapor by ionization-assisted deposition (IAD). Infrared analysis showed that the polymerization reaction was enhanced by increasing the electron current used for irradiation. The deposition polymerization was effective in improving the uniformity and thermal stability of the film. Photoluminescence analysis suggested that excimer formation can be suppressed by the deposition-polymerization of CPA. The deposited film was found to function as the hole transport layer of the organic light-emitting diode.
Quality of Anthracene Single Crystals Obtained by Physical Vapor Growth
Authors: Jo Sadaharu , Yoshikawa Hitoshi , Fujii Akane , Takenaga Mitsuru
Published: July 2005

Quality of anthracene single crystals obtained by the physical vapor growth with the horizontal arranged apparatus was examined by Laue method and atomic force microscopy (AFM). 10 mm size single crystals with minute strains could be obtained with 60 min growth time, and with 10–30 mg source material. Even in case of the occurrence of plane slips, the molecular arrangement can still keep energetically stable by the formation of quarter-monolayer (ML) steps.
High-Field NMR up to 30 T with a Hybrid Magnet
Authors: Hashi Kenjiro , Shimizu Tadashi , Goto Atsushi , Iijima Takahiro , Ohki Shinobu
Published: July 2005

NMR measurements up to 30 T were performed with the hybrid magnet installed in the National Institute for Materials Science (NIMS). The field profile and stability of superconducting, resistive and their hybrid magnets were measured using 63Cu NMR of a Cu metal. The field homogeneity of the hybrid magnet at 30 T is 186±4 ppm in the region ±5 mm from the field center along the z-axis. The magnetic field fluctuates with a total amplitude of about 30 G at 30 T (100 ppm). The present status of the hybrid magnet for high-resolution solid-state NMR measurements is discussed.
Using Mathematical Methods to Compensate for Problems Resulting from Differences in Material Properties for Remote-Field Eddy Current Testing in Tubes
Authors: Jeng Jin-Jhy
Published: July 2005

Remote-field eddy current (RFEC) testing is a nondestructive testing method. It has been comprehensively applied to detect wall loss in ferromagnetic tubes. According to our experience, the problem of variations in a material's electromagnetic characteristics often occurred in practice in carbon steel tubes. Therefore, if we fail to compensate for changes in electromagnetic characteristics during inspection, an error of evaluation will be generated. This study applied the skin-depth theory of RFEC and geometric relationships on the voltage plane to derive a compensatory model using a mathematical methodology. The new evaluation curve established on the basis of this mathematical methodology compensates for the error contributed by changing electromagnetic characteristics in the tube. The method offered by this study has proved to be reasonable, feasible and acceptable in terms of its mathematical derivation and in comparison with experimental result.
Precise Determination of Hydrostatic Pressure Correction Coefficient of Triple Point Cell of Water using Cryogenic Current Comparator Bridge
Authors: Nakanishi Masakazu , Sakurai Hirohisa
Published: July 2005

Applying a cryogenic current comparator bridge to resistance thermometry, the temperature distributions along the thermometer wells of two triple point cells of water are precisely measured using a standard platinum resistance thermometer with low measuring currents of about 0.1 mA. The average hydrostatic pressure coefficient of the two cells calculated from the temperature distributions is -0.854(38) mK/m. This value agrees well with the reported value of -0.856 mK/m, but is not consistent with the recommended value of the International Temperature Scale of 1990, -0.73 mK/m.
Development of Hybrid Thermistor Free of Magnetic Field Effect
Authors: Nara Koichi
Published: July 2005

A hybrid thermistor was developed to realize a thermometer which is practically free of the magnetic field effect. Its design involves placing two kinds of thermistors in a bridge configuration so that the magnetic field effects cancel each other. The effect of the magnetic fields on the proposed sensor was precisely studied using the triple point of water. The correction against the magnetic fields was smaller than 4 mK for the magnetic fields of up to 15 T.
New Topographic Method of Detecting Microdefects Using Weak-Beam Topography with White X-Rays
Authors: Kajiwara Kentaro , Kimura Shigeru , Chikaura Yoshinori
Published: July 2005

We describe a new topographic method of detecting microdefects in nearly perfect crystals. By this method, faint kinematical images of microdefects are observed with minimized dynamical background intensity using the interference effects of X-rays in a sample crystal. We demonstrate the capability of the method by observing “A-swirl” defects in floating-zone (FZ) silicon. The dynamical background intensity is markedly reduced, and weak kinematical images could be observed.
Fabrication Technique for Preparing Nanogap Electrodes by Conventional Silicon Processes
Authors: Hashioka Shingi , Tsuritani Hiroyuki , Obata Tsutomu , Kadosaki Masahiro , Fujiki Satoshi , Tanino Katsumi
Published: July 2005

A fabrication technique for preparing nanogap electrodes, such as a gold (Au) nano electrode, using conventional silicon (Si) processes–photolithography, etching, thermal oxidation and deposition–is proposed. Stencil substrates are prepared using the Si processes. Then, without requiring complicated technology, nanogap structures can be formed using the technique. Numerous kinds of materials can be selected as an electrode. The mass production of a sensing device for the detection of deoxyribonucleic acid (DNA), or a so-called DNA chip, can be realized at a low cost.
Feasibility of High-to-Low Design for Advanced Rewritable High-Density Digital Versatile Disc
Authors: Wang Ming-Wen , Chen Hon-Lun
Published: July 2005

The low-to-high reflective design has been widely adopted for the by advanced rewritable high-density digital versatile disc (HD DVD-ARW). Current DVD discs are all of high-to-low reflective design; therefore, we believe that this design can be utilized for the HD DVD-ARW disc. This note shows the structure of a high-to-low reflective design for a HD DVD-ARW. It indicates that the crystalline reflectivity is greater than the amorphous reflectivity. In order to achieve high-to-low reflective design, an optical simulation and sample test have been performed, including the design of the thickness of each layer, the measuring of reflectivity and modulation, and an eye-pattern test. The feasibility of the high-to-low HD DVD-ARW disc is successfully demonstrated.
Radiographic Characterization of Thermal Spray Jets Produced by Electrothermal Explosion of Ceramic Powders
Authors: Mizusako Fumiki , Tamura Hideki , Kondo Ken-ichi
Published: July 2005

Thermal spray jets composed of Zr–B–O molten particles produced by the electrothermal explosion of a mixed powder of Zr and B2O3 were quantitatively characterized of their velocity, volumetric mass density, and mass velocity by flash radiography, to investigate a unique characteristic of a coating formed by using such jets, i.e., the mixing of a substrate material with a coating. Yttria-stabilized zirconia balls were used as tracers of jet flow. Mass velocity, i.e., mass flow rate per unit cross section of the flow, in a cylindrical space in front of the virtual position of a substrate was calculated using the velocity of the tracers and the volumetric mass density of the jet. The maximum mass velocity in the present spraying was two orders of magnitude larger than that in conventional plasma spraying. Thus, the very high mass velocity probably contributes to the appearance of the unique characteristic.
Modeling of the Drying Process of Liquid Droplet to Form Thin Film
Authors: Ozawa Kin'ya , Nishitani Eisuke , Doi Masao
Published: July 2005

The drying process of thin films of polymer solutions or colloidal suspensions with a pinned contact line is investigated theoretically. The time evolution of the surface shape is calculated by taking into account of the solvent evaporation, the internal flow driven by surface tension, and the gelation (or solidification) of the fluid. It is shown that the final shape of the solidified film changes from dot-type to ring-type as the initial concentration of solute increases, or the evaporation rate decreases, but this is due to a rather intricate balance of the change of the solvent evaporation rate and the change of viscosity.
Numerical Local-Index-Integration Method of Efficient Beam Propagation Simulations
Authors: Kim Kyoung-Youm , Han Dongkyoon , Jung Suntae
Published: July 2005

A numerical local-index-integration (NLII) method of the efficient beam propagation simulation and modal analysis of optical waveguides is presented. This method can handle abrupt discontinuities in the refractive index profile quite effectively in a general way that it can be applied to the analysis of inhomogeneous waveguides having various types of index distribution, which conventional index-averaging methods have failed to handle.
Defect Effect on Electrical Transport of Multiwalled Carbon Nanotubes
Authors: Hsiou Yu-Feng , Chen Chiidong , Chan Ching-Hsu , Stobinski Leszek , Yang Ying-Jay
Published: July 2005

The low-temperature transport properties of individual multiwalled carbon nanotubes are investigated at low temperatures using the multiple-probe technique. A low-ohmic contact between an electrode and a tube is prepared to prevent the influence of contact. Measurements using two- and four-probe techniques show Coulomb oscillations with nearly the same periods, indicating that the tunneling barriers are inside the tubes between each pair of electrodes. The experiment and the theoretical simulation suggest the existence of local barriers being responsible for the formation of a chain of weakly coupled islands and for the observed Coulomb blockade characteristics.
Electronic Transport of a Carbon Nanotube Quantum Dot in Different Coupling Regimes
Authors: Maki Hideyuki , Ishiwata Yoichi , Suzuki Masaki , Ishibashi Koji
Published: July 2005

Electronic transport properties of weakly and strongly coupled carbon nanotube quantum dots are investigated using one device. After transition from a weakly coupled dot to a strongly coupled dot, both height increases and broadening of Coulomb peaks are observed due to increasing tunneling rate. From the measurements of Coulomb diamonds, twofold degeneracy is observed for a weakly coupled dot, and twofold and fourfold degeneracy is observed for a strongly coupled dot. The excitation lines due to the confined levels disappear after the transition to strong coupling.
Penetration-Depth Characteristics of Evanescent Fields at Metal Attenuated Total Reflection
Authors: Wakamatsu Takashi , Aizawa Kento
Published: July 2005

Evanescent waves generated on a metal surface at attenuated total reflection (ATR) were detected with a fluorescent-dye-coated probe tip. The field intensity of the metal ATR evanescent waves is considerably larger than that of total internal reflection (TIR) evanescent fields on a dielectric surface, but the ATR-field penetration depth depends only upon the incident angle of excitation light at a fixed wavelength; at the same incident angle, it is nearly the same value as that of the TIR fields.
Doping Effects on Thermoelectric Properties of Higher Manganese Silicides (HMSs, MnSi1.74) and Characterization of Thermoelectric Generating Module using p-Type (Al, Ge and Mo)-doped HMSs and n-Type Mg2Si0.4Sn0.6 Legs
Authors: Aoyama Ikuto , Kaibe Hiromasa , Rauscher Lutz , Kanda Toshio , Mukoujima Mika , Sano Seijiro , Tsuji Toshihide
Published: July 2005

The effect of Al Doping on the thermoelectric properties of higher manganese silicides, MnSi1.74 (HMSs) parallel and perpendicular to the c-axis was investigated. It was found that Al doping increased electrical conductivity and decreased thermoelectric power parallel to the c-axis, because Al doping of the Si site increased carrier density according to the valence control rule. Al doping was also effective for lowering thermal conductivity and raising the figure of merit parallel to the c-axis. After optimizing the Al content (y=0.0035), the thermoelectric properties of (Al, Ge and Mo)-doped HMSs parallel and perpendicular to the c-axis were evaluated and compared to those of nondoped and Al-doped HMSs. Two types of thermoelectric module consisting of n-type Mg2Si0.4Sn0.6 and p-type (Al, Ge and Mo)-doped HMSs legs parallel (or perpendicular) to the c-axis were fabricated, and their thermoelectric performances were compared to each other. The discrepancy between the measured maximum output power and the value estimated from the thermoelectric data of constituent materials was well explained by the resistance of a porous Al electrode. The measured heat flux of the module was also compared to the estimated heat flux. The maximum energy conversion efficiency of the module parallel to the c-axis was clearly higher than that perpendicular to the c-axis, because of a higher output power and a lower heat flux, and was higher than 7% at ΔT=520 K (303–823 K).
Carbon Nanofiber Composite as a Catalytic Hydrazine Decomposition Support for Satellite Propulsion
Authors: Vieira Ricardo , Bernhardt Pierre , Ledoux Marc-Jacques , Pham-Huu Cuong
Published: July 2005

The aim of this work is to determine the catalytic performance characteristics of iridium on a carbon nanofiber support with macroscopic shaping in the catalytic decomposition of hydrazine. The obtained performance characteristics obtained are compared with those of a commercial catalyst, Shell 405. Catalytic experiments are carried out in a 2 N microthruster placed inside a vacuum chamber in order to reproduce natural conditions.
Development of Substrate Structures and Processes for Practical Applications of Various Surface Acoustic Wave Devices
Authors: Kadota Michio
Published: July 2005

The author and coengineers have developed, put to practical use, mass-produced, and commercialized various surface acoustic wave (SAW) devices. Their success depended largely on the development of SAW substrate materials, SAW device structures, and the processes of producing with the cooperation of many engineers. The author reports the development and practical applications of several SAW devices: (1) ZnO/glass structure SAW filters for video intermediate frequency (VIF) for televisions (TVs) or video cassette recorders (VCRs), (2) small resonators and filters using Bleustein-Gulyaev-Shimizu (BGS) wave's edge reflection on ceramic substrates, (3) small filters using shear horizontal leaky SAWs on heavy-density-metal electrode/quartz structures, (4) ZnO/quartz structure SAW filters, and (5) SAW duplexers with excellent temperature characteristics for personal communication services (PCSs) in the US.
Digital Equivalent Circuits for Acoustic Field Based on Discrete Huygens' Modeling
Authors: Tsuchiya Takao , Kagawa Yukio
Published: July 2005

A digital equivalent circuit for a three-dimensional acoustic field is developed on the basis of the discrete Huygens' model (DHM) in which the propagation and scattering of waves are simulated as the sequences of impulses scattering as Huygens' principle states. The scattering matrix of a DHM element for propagation velocity variation is first derived. Applying the z transformation to the scattering matrix, the transfer function in the z-domain is then derived. The transmission characteristic is numerically discussed in comparison with the analog equivalent circuit model.
Ion Trapping Phenomenon in UVSOR Electron Storage Ring
Authors: Mochihashi Akira , Katoh Masahiro , Hosaka Masahito , Hayashi Kenji , Yamazaki Jun-ichiro , Takashima Yoshifumi , Hori Yoichiro
Published: July 2005

A vertical betatron tune shift depending on beam current under multibunch condition was observed in the UVSOR electron storage ring. Vertical tune increased as beam current decreased, and the slope of the tune shift depended on the condition of the vacuum in the ring. Such a change in vertical tune was explained by a change in the stability condition of trapped ions with beam current. The experimental results were discussed with analytic and tracking calculations.
Analysis of Propagation of Ultrasonic Pulses in Dispersive Media Using Group Delay Concept
Authors: Sugasawa Shinobu
Published: July 2005

A new analytical technique of the propagation of ultrasonic pulses in dispersive or nondispersive media is proposed. First, on the basis of the concept of group delay, we develop the theory as follows: (1) group delay is deduced directly from the Fourier transform of waveforms, and (2) cross-correlation theory is extended to a total measurement system which may include, for example, a sensor, couplant, amplifier, and A/D converter. Then, a fundamental result that the group delay between wave motions generated in a medium is exactly the same as that of corresponding waveforms observed by an observer is obtained. Next, this result is applied to improve the conventional pulse-echo method, and it is shown that by preparing two specimens of the same material but with different thicknesses, correct group delay in propagation can be obtained even though no physical or mechanical constants of the couplant or sensor may be known. In order to apply the results to the pulse-echo method, measurements of phase and group velocity in synthetic fused silica were also attempted.
Reflection and Refraction of Elastic Waves in Solids at Finite Temperatures up to Melting Points
Authors: Sugiyama Masaru , Chaki Mikio
Published: July 2005

On the basis of the recently proposed thermo-mechanical continuum model for elastic solids, several quantities characterizing reflection and refraction in solids, that is, amplitude ratios among incident, reflected and refracted waves, reflectivity, transmissivity, critical angle and temperature gap at an interface, are analyzed and discussed in a wide temperature range including a melting point as a limiting case.
Directional Trimming of Radiated Ultrasonic Beam Using Decentered Annular Transducer Array
Authors: Masuyama Hiroyuki , Mizutani Koichi , Nagai Keinosuke
Published: July 2005

By using a decentered annular transducer array, the directional trimming of radiated ultrasonic beams is examined. In the proposed method, the number of array elements for decentering is minimized, so the decentering operation is more simplified in comparison with that in the conventional decentering method. From the results of the calculation for the examination of the aspect of the radiated beam, it is shown that the center of the generated narrow beam moves at a sound axial distance from the sound source that is determined by the actual decentered element, and that the slippage of the center of the beam is proportional to the decentering ratio of the decentered element. From these results, the directional trimming of the radiated beam is confirmed. The technique presented here is highly simplified; thus, its applicability should be high in the production of practical sound sources.
Behavior of Director Orientation near Interface of Nematic Liquid-Crystal Cell Evaluated Using Shear Horizontal Wave Propagation
Authors: Moritake Hiroshi , Kim Jaeki , Yoshino Katsumi , Toda Kohji
Published: July 2005

The nematic liquid-crystal director orientation in the vicinity of a glass plate is investigated in relation to the acoustic phase delay change of a shear horizontal (SH) wave propagating in a cell structure. The relationships between the phase delay change and the electric field applied to the liquid-crystal layer are given for various layer thicknesses of the liquid-crystal layer, comparing with the penetration depth of the mechanical displacement. The phase-velocity change of the SH wave observed upon applying an electric field is related to the change of the liquid-crystal director angle near the interface with the glass plate, which is independent of the thickness of the liquid-crystal layer. The decay time of the director reorientation under application and removal of applied voltage is nearly independent of the applied electric field and the thickness of the liquid-crystal layer. The present method using an SH wave propagating in the liquid-crystal cell is favorable for estimating the liquid-crystal director orientation in the region very near the substrate glass.
Acoustic Study of Martensitic Phase Transformation in TiNbAl Shape Memory Alloy
Authors: Tarumi Ryuichi , Yonemoto Tomohiro , Ogi Hirotsugu , Hirao Masahiko , Inamura Tomonari , Hosoda Hideki , Miyazaki Shuichi
Published: July 2005

Martensitic phase transformation from the β to the α'' phase (and vice versa) in a TiNbAl alloy system has been studied by ultrasound spectroscopy. Resonance frequencies and corresponding internal frictions are measured from ambient temperature to 12 K by electromagnetic acoustic resonance (EMAR) and resonant ultrasound spectroscopy (RUS) coupled with laser Doppler interferometry. Both in the cooling and heating processes, we observed a marked decrease in resonance frequency and an increase in internal friction approaching the transformation temperatures. The analysis of temperature dependence in the elastic moduli indicates that lattice anharmonicity in the longitudinal acoustic mode may play a dominant role in the martensitic phase transformations.
Three-Dimensional Measurement for Absolute Value of Polarization Angle by Scanning Nonlinear Dielectric Microscopy
Authors: Sugihara Tomoyuki , Odagawa Hiroyuki , Cho Yasuo
Published: July 2005

A technique for measuring the absolute value of ferroelectric polarization angles by scanning nonlinear dielectric microscopy (SNDM) is proposed and demonstrated. In this experiment, a periodically poled LiNbO3(PPLN), which has a three-dimensional domain structure, is observed. The measured polarization angles agreed well with the actual polarization orientations, and the obtained values of polarization angles allowed an accurate visualization of the microdomain structure in PPLN. Through this experiment, we confirmed that 3D SNDM, which can measure in both the vertical and lateral polarization directions, is a useful technique for the absolute evaluation of the three-dimensional polarization direction.
Direct Observation of Sinusoidal Ultrasonically Induced Birefringence in Liquid Crystal in the Isotropic Phase
Authors: Matsuoka Tatsuro , Mizutani Yoshitaka , Koda Shinobu
Published: July 2005

Direct observation of sinusoidal ultrasonically induced birefringence was successfully carried out in 4-cyano-4'-pentylbiphenyl in the isotropic phase. The temperature dependence of the birefringence per unit intensity was compared with the estimated value using the theoretical expression for ultrasonically induced birefringence based on the de Gennes' phenomenological theory for translational-reorientational coupling. The agreement of the experimental results with those from the estimation validates the theoretical treatment.
Real-Time Measurement of Acoustic Properties of Coating Material Using Surface Wave and Plate Wave
Authors: Horie Kunihiro , Nishihira Morimasa , Imano Kazuhiko
Published: July 2005

A real-time measurement method for the variation of the acoustic properties of coating materials painted on a metal plate surface was studied experimentally. An experimental system, which detects in-phase difference and quadrature-phase difference, was devised. Surface waves or plate waves were transmitted and received on the aluminum plate with water-based paint using a pair of angle probes, and the amplitude and phase difference of the received wave signal were measured by real-time monitoring. The attenuation and phase shift of the received wave signals were calculated by comparing the acoustic properties with and without the paint. The state change of the paint was successfully monitored in real time from the attenuation and phase shift of the plate wave.
Behaviors of Dielectric Superlattice Thin Films Composed of Silicate Glass Nanolayers
Authors: Uno Takehiko , Noge Satoru , Shimotori Hirotaka
Published: July 2005

We report on the piezoelectricity, anomalous photovoltaic effect and photoluminescent characteristics of super-lattice films composed of silica glass nanolayers. It was clarified that layer boundaries of the superlattice structure were effective for inducing piezoelectricity. Furthermore, we observed an anomalous photovoltaic effect in the silica superlattice film. White light emission upon ultraviolet irradiation was observed in both the asdeposited and thermal-treated films.
Experimental Study of Acoustic Properties of (0-3) Composite Materials for Intermediate Layer or Backing of Ultrasonic Transducers
Authors: Sugawara Keisuke , Nishihira Morimasa , Imano Kazuhiko
Published: July 2005

The acoustic properties of composite materials used for an intermediate layer or backing of an ultrasonic transducer are studied experimentally. (0-3) composite materials are formed from a mixture of epoxy resin and tungsten powder for various weight ratios and their acoustic properties are measured. The experimental results are compared with the results predicted by different models, which are based on the elastic-wave scattering theory, to verify if the measured acoustic properties agree with theoretical estimations. For the ultrasonic velocities, the estimations of the Devaney model were closest to the experimental results. The weight fractions of tungsten powder for the composite materials, which have objective acoustic properties, can easily be estimated by theoretical calculations using the Devaney model.
(Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-BaTiO3-Based Lead-Free Piezoelectric Ceramics
Authors: Makiuchi Yoichi , Aoyagi Rintaro , Hiruma Yuji , Nagata Hajime , Takenaka Tadashi
Published: July 2005

The piezoelectric properties of lead-free x(Bi1/2Na1/2)TiO3-y(Bi1/2K1/2)TiO3-zBaTiO3 [BNBKy:z(x); y:z = 4:1 and 2:1, x+y+z=1] with tetragonal compositions were investigated, focusing on the secondary phase transition T
2 from the ferroelectric to antiferroelectric phases. Although the T
2 temperatures of BNBK near the MPB composition remained at about 115°C, T
2 rapidly shifted to a higher temperature of 200°C or higher for the off-MPB composition [x≤0.75 for BNBK4:1(x) and x≤0.78 for BNBK2:1(x)]. The piezoelectric activities of off-MPB compositions decreased with decreasing the amount (x) of BNT. The larger piezoelectric constant d
33=135 pC/N, the higher secondary phase transition temperature T
2=197°C, and the coupling factor k
33=0.45 with a good temperature dependence were obtained for BNBK2:1(0.78).
Photoacoustic and Photoluminescence Characterization of Passivated and Unpassivated Mn-Doped ZnS Nanoparticles
Authors: Cruz Almira Briones , Shen Qing , Toyoda Taro
Published: July 2005

In this study, passivated and unpassivated nanocrystalline ZnS with varying Mn2+ concentrations (ZnS:Mn) were synthesized and their photoacoustic (PA) and photoluminescence (PL) characteristics were studied. The PA intensity peak for the nanocrystalline ZnS was found to be blue-shifted compared with that for the bulk material due to quantum confinement effects. The difference of the PA signals of doped ZnS and undoped ZnS yielded the Mn2+ optical absorption spectra. The intensity of the PA peak increased linearly with Mn concentration. The PL spectra showed a peak position at 2.08 eV corresponding to the d–d transition of Mn2+. For the unpassivated sample, a decrease in the PL intensities for higher Mn concentrations was observed. This could be attributed to concentration quenching. Addition of acrylic acid as a passivator led to an increase in PL intensity for all Mn concentrations and prevented the decrease in the PL intensity for higher Mn concentrations. These could be attributed to the surface passivation, which reduces the nonradiative recombination probabilities, thus increasing PL intensities.
In Situ Monitoring of Solid-Liquid Interface of Aluminum Alloy Using High-Temperature Ultrasonic Sensor
Authors: Ihara Ikuo , Burhan Dikky , Seda Yoshihisa
Published: July 2005

A high temperature ultrasonic sensor with a titanium buffer rod has been applied to the in situ monitoring of the solid-liquid interface of an aluminum alloy (Al-12.6%Si) during unidirectional solidification at 700°C. The ultrasonic sensor consists of a conventional piezoelectric transducer, a titanium buffer rod as an acoustic waveguide and a cooling system. Its length is approximately 300 mm. This ultrasonic sensor, because of the unique characteristics of titanium, provides not only good acoustic coupling to molten aluminum but also high-corrosion resistance. Pulse echo measurements in the molten aluminum alloy are performed using the sensor at 2.25 MHz. A clear reflected echo from a stable solid-liquid interface of the aluminum alloy has been successfully monitored. In addition, the reflected echo from the growing interface during unidirectional solidification has also been monitored. The growth rate of the interface was determined to be 0.12 mm/s from the monitored echo.
Impedance Estimations from Bunch Lengthening in the Pohang Light Source
Authors: Ko Joung-Moo , Chung Suk-Min , Kim Eun-San , Park Chong-Do , Naito Takashi
Published: July 2005

Bunch lengthening in the Pohang Light Source storage ring has been investigated. With the three kinds of impedance models, the impedances of the storage ring are estimated by fitting the solutions of the Haïssinski equation and the measured bunch lengthening. The ring impedances estimated by a series R+L impedance model indicate an inductance of L=13.7±3.5 nH and a resistance of R=743±84 Ω. The behaviors of the measured bunch lengthening are compared with those obtained from the estimated impedances. These results show a good agreement. The threshold beam current is estimated to be 7.4 mA. The scaling law for the bunch lengthening above microwave instability threshold is obtained as σ
x
=0.437I
1/3.35. Using the Keil–Schnell criterion, longitudinal broadband impedance of the ring is estimated to be 0.24 Ω.
Resonant Ultrasound Microscopy with Isolated Langasite Oscillator for Quantitative Evaluation of Local Elastic Constant
Authors: Ogi Hirotsugu , Tian Jiayong , Tada Toyokazu , Hirao Masahiko
Published: July 2005

A resonant-ultrasound-microscopy method has been developed for measuring the local Young's modulus of a material. This method detects the effective Young's modulus through the resonance frequency of a langasite (La3Ga5SiO14) oscillator touching the specimen. Because the vibration of the oscillator is induced and detected with a solenoid coil in noncontacting, wireless, and electrodeless way, it is affected only by its contact with the specimen, achieving an absolute measurement. Elastic-constant mapping was performed on cross sections of a duplex stainless steel and a NbTi/Cu superconducting wire. Analysis with the static contact stiffness predicts the frequency change smaller than that measured, and the necessity of considering the dynamic contact stiffness is discussed.
Nonlinear Ultrasonic Wave Detection by Electromagnetic Acoustic Transducer [EMAT] for Guided Wave
Authors: Murayama Riichi , Yamaguchi Kazuhiro
Published: July 2005

When an ultrasonic wave is injected into a crack, if the width of the crack opening is of almost the same order as the displacement of the ultrasonic wave, the crack may be closed or opened. As a result, the waveform of the received ultrasonic wave is different from that of the incident ultrasonic wave. Therefore, regarding the incident ultrasonic wave, its harmonic frequency components or ultrasonic velocity changes as it penetrates the crack. However, the nonlinearity of a solid material is very small compared with that of a liquid medium, and a liquid medium with a high nonlinear efficiency had to be used as a coupling medium. We then attempted to apply an electromagnetic acoustic transducer (EMAT), which does not require a coupling medium. In addition, we studied the conditions under which the EMAT could alternately drive a Lamb wave and a shear horizontal (SH)-plate wave to detect nonlinearity in an ultrasonic wave. Although we observed an increase in the higher frequency components when a Lamb wave was perpendicularly injected into a V-shaped slit, this was not observed when using the SH-plate wave. Conversely, when a Lamb wave and an SH-plate wave were injected in parallel into the V-shaped slit, the received signal characteristics of the SH-plate wave were not affected by the Lamb wave; the received signal characteristics of the SH-plate wave were monitored for any change. This is indicates that the new nonlinear ultrasonic wave detection method can also provide information on the direction of a crack.
Ultrasonic Fog Detector for Greenhouse with Evaporative Fog Cooling System
Authors: Mizutani Koichi , Futamata Riku , Itoga Kazuya , Ishii Masahisa
Published: July 2005

To improve the spray control of evaporative fog cooling systems in greenhouses, we propose an ultrasonic fog detector. Conventional evaporative fog cooling systems have not been equipped with fog detectors and spray control has not been sufficient. The effect of fog on the amplitude and phase of ultrasonic waves between a loudspeaker and a microphone was electrically measured by quadrature detection. From the laboratory experiment using a sound probe with a 300 mm base line, the phase of the propagation characteristics showed marked lowering only while fog exists along the propagation path. In a greenhouse experiment using a sound probe with a 740 mm base line, similar results are obtained. In these experiments, the existence or nonexistence of fog was detected by the sound probe at the frequency of 40 kHz.
High-Density Single-Poly Electrically Erasable Programmable Logic Device for Embedded Nonvolatile Memory Applications
Authors: Lee Kung-Hong , King Ya-Chin
Published: July 2005

A novel electrically erasable programmable logic device (EEPLD) memory cell with new program and erase operations fabricated by a standard complementary metal–oxide–semiconductor (CMOS) logic process is presented. The cell which consists of two metal–oxide–semiconductor field effect transistor (MOSFET) transistors in series is programmed by select-gate-controlled drain avalanche hot hole injection and erased by channel hot electron injection. The cell exhibits good programming and erasing characteristics along with endurance up to 105 cycles, and 1000 h of data retention at 150°C. A new self-converged programming scheme is investigated for multilevel or analog storage. Without a P-well or an N-well serving as a coupling gate, the novel cell provides the smallest area size per bit reported for a single-poly nonvolatile memory. With its small cell size and full compatibility with the standard CMOS logic process, the novel EEPLD can be easily adopted in highly integrated VLSI systems.
A Simple Technique for Realizing an Ultrasonic Anemometer Using a Loudspeaker
Authors: Kudo Kousuke , Mizutani Koichi , Itoga Kazuya
Published: July 2005

We describe a simple technique for the realization of a two-dimensional ultrasonic anemometer using a loudspeaker. The ultrasonic anemometer was realized in order to reduce the number of acoustic transducers. Two sound propagation paths were configured by the loudspeaker, a microphone and an acoustic reflector. The number of loudspeakers was reduced to one by using a reflected sound from the acoustic reflector. The propagation path of the reflected sound (reflected path) was tilted at an angle 45 deg from the propagation path of the direct sound (direct path). The reflected path was received at the microphone after reflection at the acoustic reflector. Experiments were performed under winds of 4.0 m/s and 5.5 m/s at the center of the measurement area. The lengths of the direct and the reflected paths were 0.5 m and 0.71 m. The wind velocities were 2.8 m/s and 3.0 m/s, respectively. Results showed that the ultrasonic anemometer measured mean wind velocities in the measurement area.
Application of Air-Coupled Ultrasound to Noncontact Surface Roughness Evaluation
Authors: Sukmana Deden Dian , Ihara Ikuo
Published: July 2005

This paper presents the feasibility of ultrasonic roughness evaluation using air-coupled ultrasound. An experiment has been conducted using broadband air-coupled capacitance transducers with a center frequency of 0.5 MHz in pitch-catch mode. Specimens with a relatively large range of root-mean-square roughness, Rq, from 0.04 µm to 244 µm, are used. The reflected ultrasonic waves from the specimens were measured in a specular configuration and the relationship between the amplitude of the coherent component of the reflected wave and the surface roughness was obtained. A Kirchhoff-based scattering model was used to investigate the experimental results. The results show that the amplitude of the coherent component decreases significantly with surface roughness in the range of normalized roughness less than 100 µm·MHz.
Reflection-Type Ultrasonic Phase Conjugate Imaging System with a Waveguide
Authors: Ohno Masahiro , Kato Takahiro , Kokubo Akira , Yamamoto Ken
Published: July 2005

A reflection-type ultrasonic C-mode imaging system with an ultrasonic phase conjugator and a waveguide has been built, and images at 10 MHz have been obtained for metal samples with surface undulations. Surface or sub-surface elastic properties were visualized with a small influence of the surface roughness. The waveguide worked to enlarge the effective aperture of the phase conjugator, to smooth the incident-angle dependence of the phase conjugate reflectivity, and to improve the signal-to-noise ratio of the phase conjugate signals. Schlieren images of the ultrasonic fields in the system are also presented.
B/A Measurement for Liquid Media Using an LN Transducer with Inverted-Domain Layer
Authors: Saito Shigemi , Yamamoto Akira , Nakamura Kiyoshi
Published: July 2005

A system to measure the acoustic nonlinearity parameter B/A for a liquid medium utilizing a high-frequency focusing Gaussian source has been developed. The 19 MHz sound source employing a LiNbO3 (LN) plate with a ferroelectric inversion layer can emit and receive double frequency sound of 38 MHz. An LN plate with a twisted star-shape electrode is attached to a synthetic silica lens whose radius is much larger than the aperture size and thickness to generate a focused Gaussian beam. Linear properties such as the density, sound speed and attenuation coefficient are determined through a comparison of the pressure amplitude reflected from the solid surface located at the focal plane and the reflector distance to maximize the signal amplitude with those for the case in which the medium is replaced by distilled water. Furthermore, the ratio of the second harmonic amplitude in a sound returned from the reflector set at the focal plane and that in the case of distilled water yields the B/A value through a calculation containing the linear property obtained in advance. The measured result for the linear property and the B/A value of various alcohol samples shows a reasonable agreement with the literature values.
Three-Dimensional Image Sensing in Air by Thermally Induced Ultrasonic Emitter Based on Nanocrystalline Porous Silicon
Authors: Tsubaki Kenji , Yamanaka Hiroshi , Kitada Kosaku , Komoda Takuya , Koshida Nobuyoshi
Published: July 2005

Ultrasonic three-dimensional (3-D) image sensing in air is successfully demonstrated by combining a novel thermally induced ultrasonic emission from nanocrystalline porous silicon (nc-PS) device with a condenser microphone array. The nc-PS ultrasonic emitter is composed of a patterned heater electrode, an nc-PS layer, and a single-crystalline silicon (c-Si) substrate. In this device, an ideal probe signal can be generated with little reverberation under impulse operation, since the acoustic output shows a flat frequency response in a wide range due to a quick thermo-acoustic conversion at the device surface without any mechanical vibrations. The 3-D object is detected with a spatial resolution considerably higher than that in the case of conventional techniques based on piezoelectric transducers. It is also shown that the device is available for the detection of several objects with different acoustic reflectance coefficients.
Boron-Rich Semiconducting Boron Carbide Neutron Detector
Authors: Harken Andrew D. , Day Ellen E. , Robertson Brian W. , Adenwalla Shireen
Published: July 2005

Data on the neutron detection capabilities of a variety of boron carbide/Si heterojunction diodes is presented. The pulse height spectra are compared with previously measured conversion layer devices and the variations in shape and position of the peaks are discussed.
Mode-Shape Visualization of High-Frequency Piezoelectric Devices Using Synchronized Laser System
Authors: Watanabe Yasuaki , Tsuno Koudai , Tsuda Teruyoshi , Goka Shigeyoshi , Sekimoto Hitoshi
Published: July 2005

A full-field-view laser stroboscopic system that visualizes surface mode shapes in piezoelectric resonators has been developed. The system presented is based on stroboscopic laser irradiation, laser speckle, and two-dimensional correlation image processing. We employed a high-speed laser diode synchronized to the resonator motion to develop an in-plane vibrational distribution visualizer that is capable of operation above 10 MHz. The detection sensitivity of the proposed system is ten times better than that of previous laser speckle systems.
Measurement of Concentration in Particle Suspensions Using a Converged Ultrasonic Impulse with a Broad Frequency Bandwidth
Authors: Tai Hidekazu , Kobayashi Tsutomu , Tsuzuki Kaoru
Published: July 2005

As a method to measure the concentration and acoustical properties of fine particle suspensions, we proposed a new procedure using ultrasonic attenuation, which is based on the attenuation of ultrasonic waves passing through a liquid specimen. In order to carry out the experiment, we used a focused ultrasonic impulse with a broad frequency bandwidth using a plano-concave transducer instead of a continuous wave as is utilized in the conventional method. As specimens, we used some substances composed of fine particles, the acoustic properties or sizes of which differ. As a result, it was revealed that the particle concentration and acoustical properties could be instantaneously measured easily from the attenuation information in the frequency spectrum of ultrasonic pulses. It was also clarified that the plano-concave transducer had more useful features for the measurements than polyvinylidene fluoride (PVDF) transducers.