bluuebunny/crossref_metadata_2025 huggingface dataset:
Potamo of Alexandria and the Emergence of Eclecticism in Late Hellenistic Philosophy
Authors: Hatzimichali Myrto
Published: July 2011

Eclecticism is a concept widely used in the history of ancient philosophy to describe the intellectual stance of diverse thinkers such as Plutarch, Cicero and Seneca. In this book the historical and interpretative problems associated with eclecticism are for the first time approached from the point of view of the only self-described eclectic philosopher from Antiquity, Potamo of Alexandria. The evidence is examined in detail with reference to the philosophical and wider intellectual background of the period. Potamo's views are placed in the context of key debates at the forefront of late Hellenistic philosophical activity to which he contributed, such as the criterion of truth, the first principles in physics, the moral end and the interpretation of Aristotle's esoteric works. The emergence of eclecticism is thus treated in connection with the major shift in philosophical interests and methods that marked the passage from Hellenistic to Imperial philosophy.
Vowel Patterns in Language
Authors: Walker Rachel
Published: July 2011

Linguists researching the sounds of languages do not just study lists of sounds but seek to discover generalizations about sound patterns by grouping them into categories. They study the common properties of each category and identify what distinguishes one category from another. Vowel patterns, for instance, are analysed and compared across languages to identify phonological similarities and differences. This account of vowel patterns in language brings a wealth of cross-linguistic material to the study of vowel systems and offers theoretical insights. Informed by research in speech perception and production, it addresses the fundamental question of how the relative prominence of word position influences vowel processes and distributions. The book combines a cross-linguistic focus with detailed case studies. Descriptions and analyses are provided for vowel patterns in over 25 languages from around the world, with particular emphasis on minor Romance languages and on the diachronic development of the German umlaut.
Monkeys on the Edge
Authors: Fuentes Agustín
Published: July 2011

Long-tailed macaques (Macaca fascicularis) have a wide geographical distribution and extensively overlap with human societies across southeast Asia, regularly utilizing the edges of secondary forest and inhabiting numerous anthropogenic environments, including temple grounds, cities and farmlands. Yet despite their apparent ubiquity across the region, there are striking gaps in our understanding of long-tailed macaque population ecology. This timely volume, a key resource for primatologists, anthropologists and conservationists, underlines the urgent need for comprehensive population studies on common macaques. Providing the first detailed look at research on this underexplored species, it unveils what is currently known about the population of M. fascicularis, explores the contexts and consequences of human-macaque sympatry and discusses the innovative programs being initiated to resolve human-macaque conflict across Asia. Spread throughout the book are boxed case studies that supplement the chapters and give a valuable insight into specific field studies on wild M. fascicularis populations.
Good Governance for Pension Schemes
Authors: Thornton Paul , Fleming Donald
Published: July 2011

Regulatory and market developments have transformed the way in which UK private sector pension schemes operate. This has increased demands on trustees and advisors and the trusteeship governance model must evolve in order to remain fit for purpose. This volume brings together leading practitioners to provide an overview of what today constitutes good governance for pension schemes, from both a legal and a practical perspective. It provides the reader with an appreciation of the distinctive characteristics of UK occupational pension schemes, how they sit within the capital markets and their social and fiduciary responsibilities. Providing a holistic analysis of pension risk, both from the trustee and the corporate perspective, the essays cover the crucial role of the employer covenant, financing and investment risk, developments in longevity risk hedging and insurance de-risking, and best practice scheme administration.
The constructal law origin of the logistics S curve
Authors: Bejan A. , Lorente S.
Published: July 2011

The S curve is one of the most common phenomena in nature: the spreading of populations, tumors, contaminants, innovations, economic activity. Here we show that this phenomenon can be predicted entirely by recognizing in it a flow. The flow is not by diffusion alone, rather it is a combination of tree-shaped “invasion” by convection, followed by “consolidation” by diffusion perpendicular to the invasive lines. The S curve is not unique: its scales depend on the relative magnitude of the speed of the invading lines and the diffusivity perpendicular to the lines. Tree-shaped invasion covers the territory with diffusion much faster than line-shaped invasion. The predicted S-curve flow architecture unites the designs of spreading flows and collecting flows (e.g., mining, fossil fuel extraction, Hubbert peak) in all the realms of nature: animate, inanimate, and human-made.
Chemical speciation of adsorbed glycine on metal surfaces
Authors: Han Jeong Woo , James Joanna N. , Sholl David S.
Published: July 2011

Experimental studies have reported that glycine is adsorbed on the Cu(110) and Cu(100) surfaces in its deprotonated form at room temperature, but in its zwitterionic form on Pd(111) and Pt(111). In contrast, recent density functional theory (DFT) calculations indicated that the deprotonated molecules are thermodynamically favored on Cu(110), Cu(100), and Pd(111). To explore the source of this disagreement, we have tested three possible hypotheses. Using DFT calculations, we first show that the kinetic barrier for the deprotonation reaction of glycine on Pd(111) is larger than on Cu(110) or Cu(100). We then report that the presence of excess hydrogen would have little influence on the experimentally observed results, especially for Pd(111). Lastly, we perform Monte Carlo simulations to demonstrate that the aggregates of zwitterionic species on Pt(111) are energetically preferred to those of neutral species. Our results strongly suggest that the formation of aggregates with relatively large numbers of adsorbed molecules is favored under experimentally relevant conditions and that the adsorbate-adsorbate interactions in these aggregates stabilize the zwitterionic species.
The non-equilibrium charge screening effects in diffusion-driven systems with pattern formation
Authors: Kuzovkov V. N. , Kotomin E. A. , de la Cruz M. Olvera
Published: July 2011

The effects of non-equilibrium charge screening in mixtures of oppositely charged interacting molecules on surfaces are analyzed in a closed system. The dynamics of charge screening and the strong deviation from the standard Debye-Hückel theory are demonstrated via a new formalism based on computing radial distribution functions suited for analyzing both short-range and long-range spacial ordering effects. At long distances the inhomogeneous molecular distribution is limited by diffusion, whereas at short distances (of the order of several coordination spheres) by a balance of short-range (Lennard-Jones) and long-range (Coulomb) interactions. The non-equilibrium charge screening effects in transient pattern formation are further quantified. It is demonstrated that the use of screened potentials, in the spirit of the Debye-Hückel theory, leads to qualitatively incorrect results.
The impact of pre‐admission morbidity level on 3‐year mortality after intensive care: a Danish cohort study
Authors: CHRISTIANSEN C. F. , CHRISTENSEN S. , JOHANSEN M. B. , LARSEN K. M. , TØNNESEN E. , SØRENSEN H. T.
Published: July 2011

Background: Chronic diseases are common among intensive care unit (ICU) patients and may worsen their prognosis. We examined the prevalence and impact of pre‐admission/index morbidity among ICU patients compared with a general population cohort.

Methods: Our study encompassed all 28,172 adult patients admitted to ICUs in northern Denmark in 2005–2007 and 281,671 age‐ and sex‐matched individuals from the general population. We used a nationwide hospital registry to obtain a 5‐year history of 19 chronic diseases and computed Charlson Comorbidity Index (CCI) for each study participant and grouped them into low (CCI=0), moderate (CCI=1–2), and high (CCI=3+) morbidity levels. We computed mortality and mortality rate ratios (MRRs) adjusted for confounders, and compared the mortality between ICU patients and the general population cohort.

Results: Low, moderate, and high pre‐admission morbidity levels were present in 51.5%, 34.1%, and 14.4% of ICU patients, respectively. In these groups, 30‐day mortality was 10.8%, 18.4%, and 26.7%, respectively. Three‐year mortality was 21.3%, 43.1%, and 63.2%, respectively. The adjusted 30‐day MRR was 1.30 [95% confidence intervals (CI): 1.21–1.39] and 1.86 (95% CI: 1.71–2.01) for ICU patients with moderate and high morbidity levels, both compared with a low morbidity level. The general population had a lower morbidity level and mortality at all morbidity levels throughout the study period. Interaction between ICU admission and high morbidity level added 5.1% to the mortality during the second and third year of follow‐up.

Conclusion: A high pre‐admission morbidity level was frequent among ICU patients and associated with a worsened prognosis. Morbidity had more impact on mortality among ICU patients compared with a general population cohort.
Theoretical Study on Magnetoelectric and Thermoelectric Properties for Graphene Devices
Authors: Kageshima Hiroyuki , Hibino Hiroki , Nagase Masao , Sekine Yoshiaki , Yamaguchi Hiroshi
Published: July 2011

Two of our recent theoretical efforts on elucidating the functions of graphene are reported. A first-principles calculation of the growth process of graphene islands on SiC(0001) shows that an embedded structure is energetically preferable. Island with this embedded structure do not have any broken dangling bonds at their edges. Their electronic states clearly show that they surely act as islands. Islands with zigzag edges have edge-localized states, which causes magnetoelectric effects. Graphene is also expected as a highly efficient material for thermoelectric elements according to a theoretical study. If the carrier scattering sources are adequately suppressed, the thermoelectric figure of merit greatly exceeds 1 at temperatures higher than 300 K with the Fermi energy fixed around the Dirac point. Since graphene is cheaper, resource abundant, more harmless, higher in melting temperature, and much lighter in density, than the present typical material, BiTe/Sb, many new applications could be considered.
Theoretical Study of Population Inversion in Graphene under Pulse Excitation
Authors: Satou Akira , Otsuji Taiichi , Ryzhii Victor
Published: July 2011

We study theoretically the population inversion in intrinsic graphene under optical pulse excitation at room temperature. We develop the theoretical model of carrier relaxation dynamics based on the rate equations derived from the quasi-classical Boltzmann equation. We take into account the energy relaxation and recombination by the intra and interband optical phonon (OP) scattering, and we assume that the carrier–carrier (CC) scattering is dominant so that the carrier distribution is always the quasi-Fermi distribution. Using the model developed, we demonstrate that the population inversion can be achieved under the pulse excitation even in the limiting case of the dominant CC scattering.
Preparation and Characterization of (Ba0.8Sr0.2)TiO3–Al2O3 Composite Oxide for Thin Film Capacitor
Authors: Jang Joo-Hee , Kim Tae-Yoo , Lee Chang-Hyoung , Zhang JingJing , Park Eun-Mi , Park Chan , Suh Su-Jeong
Published: July 2011

Barium strontium titanate–alumina composites were fabricated using a sol–gel and anodizing process for high performance thin film capacitors and the properties of the films were studied. The (Ba0.8Sr0.2)TiO3 (BST) films were formed by spin coating and subsequent annealing at 150–550 °C. The respective annealed films were anodized in a neutral borate solution. The capacitance density increased with increasing annealing temperature up to 450 °C but decreased at 550 °C. The capacitance density was approximately 28.46% higher with the BST coating than without the BST layer.
Estimation of Interfacial Fixed Charge at Al2O3/SiO2 Using Slant-Etched Wafer for Solar Cell Application
Authors: Ahn Youngkyoung , Choudhury Sakeb Hasan , Lee Daeseok , Sadaf Sharif Md. , Siddik Manzar , Jo Minseok , Park Sungeun , Kim Young Do , Kim Dong Hwan , Hwang Hyunsang
Published: July 2011

Al2O3 with a negative fixed charge prepared by atomic layer deposition has been reported to improve surface passivation properties for Si-solar cell applications. The high negative fixed charge at the SiO2/Al2O3 interface facilitates a low surface recombination velocity and a high effective lifetime, which result in greater performance. In this study, we adopted an effective method using a slant-etched sample with various thicknesses of SiO2 to estimate the charge densities of both the bulk and interface of Al2O3 deposited by atomic layer deposition. We found a direct correlation between lifetime and total charge density in Al2O3, which are strong functions of film thickness and annealing condition.
Polarization-Sensitive Reading Method for High-Density Optical Data Storage
Authors: Yasui Toshifumi , Saiki Toshiharu
Published: July 2011

A method is proposed for reading sub-diffraction-limited recording marks to achieve higher-density optical data storage. We utilize polarization rotation of light reflected from a recording medium owing to the inhomogeneous distribution of the transverse field perpendicular to the polarization direction of focused reading beam. Even if the readout beam simultaneously illuminates several marks, the mark pattern can still be identified by detecting the change in the polarization of the reflected signal light in addition to its intensity. The feasibility of the method was demonstrated by performing a numerical calculation and an experiment with a model recording medium.
Preparation and Characterization of Co/Pd Epitaxial Multilayer Films with Different Orientations
Authors: Tobari Kousuke , Ohtake Mitsuru , Nagano Katsumasa , Futamoto Masaaki
Published: July 2011

Co/Pd multilayer films were prepared on fcc-Pd underlayers of (001), (111), and (011) orientations hetero-epitaxially grown on MgO single-crystal substrates at room temperature by ultrahigh-vacuum rf magnetron sputtering. The structural and magnetic properties vary depending on the underlayer orientation. A multilayer film consisting of fct-Co(001) and fcc-Pd(001) single-crystal layers is formed on a Pd(001)fcc underlayer, whereas epitaxial multilayer films consisting of Co and Pd layers with fcc(111) and fcc(011) orientations are obtained on Pd(111)fcc and Pd(011)fcc underlayers, respectively. For the film grown on the Pd(001)fcc underlayer, sharp interfaces are formed between the Co and Pd layers. On the other hand, atomic mixing is observed at the Co/Pd interface for the films grown on the Pd(111)fcc and Pd(011)fcc underlayers. The CoPd-alloy layers are formed around these interfaces. The CoPd-alloy formation is enhanced in the order of (001) < (111) < (011). The multilayer films grown on the Pd(111)fcc and Pd(011)fcc underlayers show perpendicular magnetic anisotropies, whereas the film grown on the Pd(001)fcc underlayer is easily magnetized in in-plane directions. The magnetic properties are delicately affected by the crystallographic structures of Co/Pd multilayer films.
Electrical Investigation of Notch Width Dependence of Domain Wall Structure in Co/Ni Nanowires
Authors: Kondou Kouta , Hiramatsu Ryo , Koyama Tomohiro , Nakatani Yoshinobu , Chiba Daichi , Fukami Shunsuke , Ishiwata Nobuyuki , Ono Teruo
Published: July 2011

We have investigated the notch width dependence of the domain wall structure by measuring the wall resistances in Co/Ni nanowires with perpendicular magnetization. Wall resistance was abruptly increased below a notch width of 43 nm. By comparing the experimental results with theoretical calculations of wall resistance and the micromagnetic simulation of wall energy, this increase in wall resistance was found to be caused by the change in the wall structure from the Bloch to Néel wall caused by the decreased notch width.
ON-State Reliability of Solid-Electrolyte Switch under Pulsed Alternating Current Stress for Programmable Logic Device
Authors: Banno Naoki , Sakamoto Toshitsugu , Tada Munehiro , Miyamura Makoto , Okamoto Koichiro , Hada Hiromitsu , Aono Masakazu
Published: July 2011

In this paper, we describes the ON-state reliability of a nonvolatile solid-electrolyte switch for a programmable logic device (PLD). The ON-state requirement for this application is different from that of a Cu via or an interconnect, since the pulsed-AC current is applied to the switch when the voltage changes in the interconnect. We experimentally demonstrate a recovering phenomenon in the migration under AC stress and propose an appropriate ON-state resistance of 800 Ω to satisfy the requirement for a current density criterion that goes beyond the 28-nm technology node (hp28). The ON-state duration of the crossbar switch under the pulsed-AC current of 1 GHz is estimated to be over 10 years at an ambient of 150 °C.
Molten KOH Etching with Na2O2 Additive for Dislocation Revelation in 4H-SiC Epilayers and Substrates
Authors: Yao Yong-Zhao , Ishikawa Yukari , Sugawara Yoshihiro , Saitoh Hiroaki , Danno Katsunori , Suzuki Hiroshi , Kawai Yoichiro , Shibata Noriyoshi
Published: July 2011

A novel etching solution using molten KOH with Na2O2 additive (KN etching) for dislocation revelation in 4H-SiC epilayers and substrates has been proposed. Threading screw and edge dislocations (TSDs and TEDs) have been clearly revealed as hexagonal etch pits differing in pit size, and basal plane dislocations (BPDs) as seashell-shaped pits. KN etching has provided a solution to the problem that KOH etching is not effective for dislocation identification in n+-4H-SiC. The influences of SiC off-axis angles, carrier concentrations, and growth techniques on the effectiveness of KN etching have also been investigated. It has been shown that KN etching is applicable to SiC epilayers and substrates with any off-axis angle from 0 to 8° and electron concentrations from 1015 to 1019 cm-3.
Epitaxial Growth and Characterization of Rocksalt ZnO Thin Films with Low-Level NiO Alloying
Authors: Katayama Shota , Hayashi Hiroyuki , Oba Fumiyasu , Tanaka Isao
Published: July 2011

Thin films of ZnO alloyed with NiO have been grown on MgO(100) substrates using pulsed-laser deposition. An undoped film exhibits a wurtzite structure with its (1010) plane parallel to the MgO(100) surface. The rocksalt phase forms when the Ni concentration is more than 9 cation %. NiO-alloyed rocksalt ZnO films are epitaxially grown on the substrates with the cube-on-cube orientation relationship and show the single-domain structure with a rather flat surface. The direct optical band gap of the rocksalt films only slightly changes with an increase in Ni concentration up to 36 cation %.
Assessment and Extendibility of Chemically Amplified Resists for Extreme Ultraviolet Lithography: Consideration of Nanolithography beyond 22 nm Half-Pitch
Authors: Kozawa Takahiro , Oizumi Hiroaki , Itani Toshiro , Tagawa Seiichi
Published: July 2011

The major resist properties, namely, resolution, line edge roughness (LER), and sensitivity have trade-off relationships. The relationships among them are determined by the pattern formation efficiency. Because of these trade-off relationships, the assessment of resist performance has been a difficult task. The extraction of parameters associated with pattern formation efficiency is important for the proper assessment of resist materials. In this study, we improved the resist model and analysis procedure for the parameter extraction and assessed state-of-the-art extreme ultraviolet (EUV) resists. Using extracted parameters, we evaluated the expected resist performance upon exposure to a next-generation exposure tool with high numerical aperture (NA). Furthermore, assuming the technical limits of resist materials, the extendibility of chemically amplified resists was examined. It was found that the resist requirements (10 mJ cm-2 sensitivity and 1 nm LER) for the 16 nm node are achievable at NA=0.35, although they were comparable to the assumed technical limit.
Design of Pickup Coil Made of Litz Wire and Cooled at 77 K for High Sensitive Measurement of AC Magnetic Fields
Authors: Enpuku Keiji , Hirakawa Shintaro , Momotomi Ryuji , Matsuo Masaaki , Yoshida Takashi , Kandori Akihiko
Published: July 2011

We studied the performance of a copper pickup coil for high sensitive measurements of ac magnetic fields. The coil was made of Litz wire to prevent the skin effect, and was cooled at 77 K to reduce thermal noise. We first obtained an analytical expression for the coil resistance by analyzing the eddy current loss of the coil. The analytical result explains well the measured dependences of the coil resistance on the frequency, number of turns of the coil (N), and filament diameter of the Litz wire (df). Next, we show the design of the pickup coil. When appropriate values are selected forNanddf, we can expect the magnetic field noiseSB1/2< 10 fT/Hz1/2forf> 1 kHz andSB1/2< 2 fT/Hz1/2forf> 10 kHz for the pickup coil with diameter of 50 mm. The experimental results agreed with the designed values.
Monolithic Piezoelectric Sensor for Measurement of Triaxial Forces Applied to Bridge by String Vibration
Authors: Takarada Jun , Wakatsuki Naoto , Mizutani Koichi
Published: July 2011

We propose a piezoelectric sensor to investigate string vibration. This sensor has a square pyramidal structure and five electrodes on each surface, and enables us to measure triaxial forces. Measuring triaxial forces from a single sensor enables us to obtain complex vibration mechanisms, such as the string vibration of musical instruments. We designed the sensor to serve as a bridge of musical instruments and to measure triaxial forces applied by string vibration directly. A previously proposed sensor, which also serves as the bridge, has a problem regarding its charge sensitivity. To improve charge sensitivity, the newly proposed sensor is designed to have large electrodes by devising its structure. The sensitivity of the newly proposed sensor is compared with that of the previously proposed sensor using a finite element method. The sensitivity of the proposed sensor becomes higher than that of the previous sensor. In particular, the sensitivity of the proposed sensor in the horizontal direction becomes about 2.5 times higher than that of the previous one. The reason for this is that the new sensor is applied with a piezoelectric shear effect to measure its sensitivity in the horizontal direction, while the previous one is applied with a longitudinal effect. The constant of the piezoelectric shear effect is generally about two times higher than that of the longitudinal effect. Moreover, we obtain the sensitivity of the proposed sensor in the experiment. The experimental results suggest that the triaxial force can be measured by calculating the pseudo-inverse matrix of the measured sensitivity.
Quantitative Measurement of Focused Ultrasound Pressure Field Using Subtraction Shadowgraph
Authors: Omura Ryosuke , Shimazaki Yuta , Yoshizawa Shin , Umemura Shin-ichiro
Published: July 2011

In this study, the measurement of focused ultrasound pressure field by the subtraction shadowgraph method was investigated. Conventional shadowgraph is known as a fast, noninvasive, but qualitative method of ultrasound pressure field measurement. On the other hand, the subtraction shadowgraph method in this paper can provide quantitative projection images, from which the ultrasound pressure field can be reconstructed. Subtraction shadowgraph images of a focused ultrasound field were obtained, it was converted to the projection of the refractory distribution, and the focused ultrasound pressure field was reconstructed from the projection by computed tomography algorithm. The result was compared with that of hydrophone measurement, and successful reconstruction of the axi-symmetric pressure distribution of the focal field was confirmed in both lateral and axial cross sections.
Precise Measurement of Pipe Wall Thickness in Noncontact Manner Using a Circumferential Lamb Wave Generated and Detected by a Pair of Air-Coupled Transducers
Authors: Nishino Hideo , Asano Tadashi , Taniguchi Yuta , Yoshida Kenichi , Ogawa Hitoshi , Takahashi Masakazu , Ogura Yukio
Published: July 2011

In this paper, we present a novel method of accurately estimating pipe wall thickness by detecting the minute difference in the angular wave number of a circumferential (C-) Lamb wave. A C-Lamb wave circling along a circumference of a pipe is transmitted and received by a pair of noncontact air-coupled ultrasonic transducers. For the accurate detection of the angular wave number, a large number of tone-burst cycles are used so as to superpose the C-Lamb wave on itself along its circumferential orbit. In this setting, the amplitude of the superposed region changes considerably with the angular wave number, from which the wall thickness can be estimated. This method is very useful to monitor the integrity of piping in high-temperature environments because of its noncontact nature. The principle of the method and experimental verification are shown.
Analysis of Reflection Powers from a Perfectly Matched Layer for Elastic Waves in the Frequency Domain Finite Element Model
Authors: Shimada Takao , Hasegawa Koji , Sato Shingo
Published: July 2011

A perfectly matched layer (PML) is useful for truncating the computation region of scattering problems in a finite element analysis (FEA). The approximation of the open region with thick layer and discretization of it with finite elements generates reflection waves from PML boundary. However, reflection powers generated by finite element discretization have not been quantified for elastic waves. In this paper, we explain the reflection from PMLs by discretized wave number analysis of elastic plane-wave scattering, and demonstrate that the results of discretized wave number analysis give satisfactory approximations of FEA.
A Method for Estimating the Location of the Drill-Bit During Horizontal Directional Drilling Using a Giant-Magnetostrictive Vibrator
Authors: Tamura Junpei , Kawamura Youhei , Mochiji Hidemi , Sasaki Naoto , Mizutani Koichi , Okawa Hirokazu
Published: July 2011

Horizontal directional drilling (HDD) is a commonly used method for laying pipelines that avoids the need to make an open cut. However, the location of the drill-bit underground must be known at all times when using this method. As conventional electromagnetic wave-based methods are known to have several problems, for example buildings in the line of construction, the moisture content of the ground and the presence of steel towers near the construction site. Herein we suggest a new method based on the propagation of elastic waves in the ground. Thus, measurement of the elastic waves generated by a giant-magnetostrictive vibrator by sensors set on the ground allows us to obtain the differences in arrival time of this wave at each sensor by applying a cross-correlation analysis to the waveforms detected. Finally, an approximate three-dimensional (3D) location method based on these differences was designed.
Estimation for Amplitude Decrease of Discretized Hydrophone Output Voltage by Imperfect Synchronous Averaging Using External Trigger
Authors: Yoshioka Masahiro , Kikuchi Tsuneo
Published: July 2011

An estimation using a theoretical formula for the amplitude decrease of discretized hydrophone output voltage due to imperfect synchronous averaging using an external trigger in our ultrasonic field parameter calibration is described. The estimation formula is derived from a statistically expected value considering the temporal difference of the trigger as a random variable with a uniform distribution in the range of the sampling period. As a result of comparing the formula and the measured hydrophone output voltage amplitude for ultrasound up to 20 MHz, it is confirmed that the formula can estimate the amplitude decrease and be used for correction to obtain accurate ultrasonic field measurement.
Study of Relationship between Layer Profile of SiO2 and Characteristics of Surface Acoustic Wave Devices in SiO2/Al/LiTaO3 System
Authors: Takayama Ryoichi , Nakanishi Hidekazu , Iwasaki Yukio , Nakamura Hiroyuki , Goto Rei
Published: July 2011

In this paper, we describe our study of the relationship between the layer profile of SiO2 and the characteristics of surface acoustic wave (SAW) devices in the SiO2/Al/LiTaO3 system. SiO2 coating is a well-known technology to improve the temperature coefficient of frequency (TCF) of a SAW filter, but the characteristics of the SAW filter deteriorate simultaneously. In this study, we focus on the SiO2 layer profile as one of the causes of this deterioration and try to improve the characteristics of the SAW filter with the SiO2/Al/LiTaO3 structure by changing the SiO2 layer profile. The relationship between the layer profile and the characteristics of SAW resonators has been investigated by finite element method (FEM)/spectrum domain analysis (SDA). To confirm the simulation results, we fabricated several SAW resonators with different profiles of the SiO2 layer by changing deposition conditions. As a result, the simulation results were in good agreement with the experimental results, and the enhanced characteristics of the SAW resonator and filter with a low insertion loss, a steep skirt characteristic, and a low TCF of approximately -15 ppm/K have been realized.
Measurement of Amount of Generated Acoustic Cavitation: Investigation of Spatial Distribution of Acoustic Cavitation Generation Using Broadband Integrated Voltage
Authors: Uchida Takeyoshi , Takeuchi Shinichi , Kikuchi Tsuneo
Published: July 2011

We have been developing a measurement technique for the amount of generated acoustic cavitation using broadband integrated voltage (BIV), calculated from high-frequency components of broadband noise in the output signal of a cavitation sensor. BIV is a signal caused by the effect of bubbles produced by acoustic cavitation. In this study, one dimension distribution of cavitation generation in a water vessel was measured in terms of BIV and sound pressure. The results show that the peak positions of BIV and sound pressure were different. Although the sound pressure was high at the center position generating the flow toward the surface of water, BIV was low because no cavitation bubbles were trapped. Hence, BIV has potential use in the measurement of the spatial distribution of cavitation generation more accurately than sound pressure.
Estimation of Cavitation Sensor with Hydrothermally Synthesized Lead Zirconate Titanate Film on Titanium Cylindrical Pipe: Spatial Distribution of Acoustic Cavitation Field and Basic Characteristics of Cavitation Sensor
Authors: Shiiba Michihisa , Kawashima Norimichi , Uchida Takeyoshi , Kikuchi Tsuneo , Kurosawa Minoru , Takeuchi Shinichi
Published: July 2011

We developed a small cavitation sensor by the deposition of a hydrothermally synthesized lead zirconate titanate (PZT) polycrystalline film on a Ti hollow cylindrical pipe. The spatial distributions of acoustic cavitation generated in a vessel of 150 kHz sonoreactor were measured by using our cavitation sensor. We estimated the spatial distribution of acoustic cavitation by using the broad band integrated voltage (BIV) calculated from the output signal of our cavitation sensor. A similar spatial distribution of the BIV to a sonochemical luminescence pattern could be observed in the measured results. Our fabricated cavitation sensor could be applied to the measurement of sound pressure in a high-intensity ultrasound field with acoustic cavitation for a period longer than 150 without damage. We measured the spatial distribution and directivity of the receiving sensitivity for the characterization of our cavitation sensor. It is suggested from the measured results that the BIV and the cavitation signal included in the output signal from the cavitation sensor are based on the acoustic cavitation generated in the cylindrical hollow of our cavitation sensor.
Phase Change Nanodroplets and Microbubbles Generated from Them as Sources of Chemically Active Cavitation
Authors: Kawabata Ken-ichi , Maruoka Takashi , Asami Rei , Umemura Shin-ichiro
Published: July 2011

Aiming at a multidisciplinary tumor treatment with thermal and chemical mechanisms, the effect of phase change nanodroplets (PCNDs) on inducing reactive chemical species through cavitation was evaluated in vitro. By using the reaction yield of the oxidation of iodide ions to tri-iodide ions as a measure, the effect of PCNDs and PCND-derived microbubbles were investigated. The presence of PCNDs reduced the intensity threshold for chemical reaction by at least 40%. Furthermore, the threshold with PCND-derived microbubbles was 5 times lower than that with PCNDs alone. The interval of exposing the phase change trigger, which is used to generate microbubbles from PCNDs, was found to be shorter than 0.01 s for efficient induction of a chemical reaction. The reaction yields were independent of PCND concentration, thus PCND-derived microbubbles are not considered to work directly in the generation of chemical species undergoing the reaction.
Arsenite Oxidation and Treatment by Ultrasound/Iron in Aqueous Solutions
Authors: Cui Mingcan , Jang Min , Lee Seban , Kweon Boyoun , Yun Seong-Taek , Khim Jeehyeong
Published: July 2011

The oxidation and treatment of arsenite [As(III)] with ultrasound (US) and Fe(II) was investigated in aqueous solutions. The oxidation of As(III) into As(V), over 99.1%, was obtained by US450kHz. The kinetics of As(III) oxidation were interpreted using the modified pseudo-first-order kinetic model. The half life of As(III) was approximately 3.47 ×10-2 s for the US450kHz/Fe(II)0.4mg/L reaction and depended on the iron concentration. The arsenic removal capacity of complexed and coprecipitated FeAsO4(s) was estimated to be 16.12 mg per g of iron oxide. It is concluded that the sonochemical treatment of As(III) solution in the presence of Fe(II) is a simple and viable technique for the oxidation of As(III) into arsenate [As(V)] and the treatment of total arsenic.
Sonochemical Oxidation of Arsenite in Aqueous Phase
Authors: Cui Mingcan , Lee Seban , Jang Min , Kweon Boyoun , Jo Hoyoung , Khim Jeehyeong
Published: July 2011

The objective of this research is to assess critically the experimental rate data for sonochemical oxidation of arsenite [As(III)] at different frequencies and powers in the aqueous phase. The oxidative conversion of As(III) into arsenate [As(V)] was >90% in the range of 283 to 450 kHz. With a power density of 69 W L-1, the oxidation of As(III) for 40 min at 283 kHz showed a second-order rate constant of 7.1×102 M-1 s-1, whereas it was 3.8×103 M-1 s-1 at 450 kHz. As calculated by the calorimetric method, the power transferred into samples was in the range of 7–34.5 W with the two frequencies of 283 or 450 kHz. Approximately 100% oxidation efficiency was obtained with a frequency of 450 kHz and 34.5 W. As the pretreatment process, oxidation by sonication has potential applications to groundwater contaminated with both As(III) and As(V).
Dispersion Effect of Nanoparticle According to Ultrasound Exposure Using Focused Ultrasound Field
Authors: Kim Jungsoon , Kim Moojoon , Chu Minchul
Published: July 2011

The dispersion effect of a focused ultrasonic field is investigated in aqueous suspensions of TiO2 and Al2O3 nanoparticles under various exposure conditions. Within a narrow time range, the effect was proportionally enhanced with exposure time. However, the nanoparticles agglomerated again with long-time exposure. For the TiO2 nanoparticles, the optimum exposure time was 10 min at an acoustic power of 28.1 W. For the Al2O3 particles, the optimum exposure time was 3 min at an acoustic power of 11.2 W.
Experimental Attempts for Deep Insertion in Ultrasonically Forced Insertion Process
Authors: Ono Satoshi , Aoyagi Manabu , Tamura Hideki , Takano Takehiro
Published: July 2011

In this paper, we describe two attempts of obtaining deep insertion in an ultrasonically forced insertion (USFI) process. One was to correct the inclination of an inserted rod by passively generated bending vibrations. The inclination causes a partial plastic deformation, which decreases the holding power of processing materials. Two types of horn with grooves for excitation of bending vibrations were examined. The other was to make differences in vibration velocity and the phase of a rod and a metal plate by damping the vibration of a metal plate by using a rubber sheet. As results, the attempts proposed in this study were confirmed to be effective to obtain a deep insertion.
Ultrasonic Atomization Amount for Different Frequencies
Authors: Yasuda Keiji , Honma Hiroyuki , Xu Zheng , Asakura Yoshiyuki , Koda Shinobu
Published: July 2011

The mass flow rate of ultrasonic atomization was estimated by measuring the vaporization amount from a bulk liquid with a fountain. The effects of ultrasonic frequency and intensity on the atomization characteristics were investigated when the directivities of the acoustic field from a transducer were almost the same. The sample was distillated water and the ultrasonic frequencies were 0.5, 1.0, and 2.4 MHz. The mass flow rate of ultrasonic atomization increased with increasing ultrasonic intensity and decreasing ultrasonic frequency. The fountain was formed at the liquid surface where the effective value of acoustic pressure was above atmospheric pressure. The fountain height was strongly governed by the acoustic pressure at the liquid surface of the transducer center. At the same ultrasonic intensity, the dependence of ultrasonic frequency on the number of atomized droplets was small. At the same apparent surface area of the fountain, the number of atomized droplets became larger as the ultrasonic frequency increased.
Improvements in Controllability of Ultrasonic Linear Motors by Longitudinal-Bending Multilayered Transducers with Independent Electrodes
Authors: Takano Masahiro , Hirosaki Kenichi , Takimoto Mikio , Ichimura Satoru , Nakamura Kentaro
Published: July 2011

Ultrasonic motors are nonlinear in input–output characteristics, which causes problems for precise control. To obtain good controllability and realize low-cost fabrication, we proposed an ultrasonic linear motor using a multilayered transducer with independent electrode sets for the first longitudinal mode and the second bending mode. We can change the shape of the vibration locus at the friction head arbitrarily by independently controlling the amplitude and phase of each vibration component. Controllability in the proposed motor was investigated by changing the shape of the vibration locus. In the proposed motor, the nonlinear part of the input–output characteristics is suppressed to 1/20 of that in conventional ultrasonic motors. As a result, a good positioning resolution of 20 nm and a low-speed drive of 0.1 mm/s were obtained with a simple closed-loop control system.
Improvement of Characteristics of Noncontact Ultrasonic Motor Using Acoustically Coupled Two Air Gaps
Authors: Yamayoshi Yasuhiro , Hirose Seiji
Published: July 2011

The improvement of the rotational characteristics of a noncontact ultrasonic motor using a flexural traveling wave vibration disk was experimentally tried using an acoustic reflector and a double-disk rotor. By attaching the acoustic reflector over the single-disk rotor, a revolution speed of about 2300 rpm was obtained, which was about 1.4 times the maximum value without the reflector. Using a double-disk rotor instead of a single-disk rotor, a revolution speed of about 2800 rpm was achieved. From the observation of the air flow in the air gap, it was confirmed that the increase in revolution speed is attributed to the acoustic streaming induced in the air gap newly formed by the reflector and the double-disk rotor. The acoustic streaming in the new air gap is caused by the acoustic coupling between the double air gaps through the open edges of the air gaps.
Fundamental Study of Detecting Internal Defect in Building Materials Using High-Intensity Aerial Ultrasonic Waves with Finite Amplitude
Authors: Osumi Ayumu , Doi Kazuki , Ito Youichi
Published: July 2011

An impact acoustic method and an infrared method are often used to detect peeling in building materials such as concrete and tile. However, both of these methods are susceptible to human error and require long measurement times. In this study, we examine a new method that uses high-intensity aerial ultrasonic waves to detect peeling in building materials. Specifically, we have developed a noncontact method of detecting defects in building materials by analyzing the vibration of an object excited with high-intensity aerial ultrasonic waves of finite amplitude at a frequency of 26.8 kHz. We prepared artificial peeling samples consisting of tile and concrete plates. The results indicated that there is clearly a large difference in vibration velocity and distortion rate between the area with artificial peeling and the area without peeling. Therefore, it is possible to detect peeling of building materials by this method.
Effect of Ultrasonic Wave Irradiation Sequence in Microhollow Production Produced by Bubble Cavitation
Authors: Yamakoshi Yoshiki , Miwa Takashi
Published: July 2011

Sonoporation, which makes micropores through a cell membrane by bubble cavitation, improves the efficacy in ultrasonic wave drug delivery systems. However, the effects of bubble cavitation are affected largely by bubble condition, such as bubble density and bubble aggregation, just before the irradiation of a high-intensity ultrasonic wave. Aiming at preparing a specific bubble condition in bubble cavitation, a method which uses the frequency modulation of a pumping ultrasonic wave was proposed. In this paper, the effects of the ultrasonic wave irradiation sequence are evaluated under different flow velocities and bubble densities. The spatial correlation between microbubble clouds produced by the pumping ultrasonic wave and the microhollows produced by the bubble cloud cavitation is also discussed.
Estimation of Scatterer Diameter by Normalized Power Spectrum of High-Frequency Ultrasonic RF Echo for Assessment of Red Blood Cell Aggregation
Authors: Fukushima Taku , Hasegawa Hideyuki , Kanai Hiroshi
Published: July 2011

Red blood cell (RBC) aggregation, as one of the determinants of blood viscosity, plays an important role in blood rheology, including the condition of blood. RBC aggregation is induced by the adhesion of RBCs when the electrostatic repulsion between RBCs weakens owing to increases in protein and saturated fatty acid levels in blood, excessive RBC aggregation leads to various circulatory diseases. This study was conducted to establish a noninvasive quantitative method for assessment of RBC aggregation. The power spectrum of ultrasonic RF echoes from nonaggregating RBCs, which shows the frequency property of scattering, exhibits Rayleigh behavior. On the other hand, ultrasonic RF echoes from aggregating RBCs contain the components of reflection, which have no frequency dependence. By dividing the measured power spectrum of echoes from RBCs in the lumen by that of echoes from a posterior wall of the vein in the dorsum manus, the attenuation property of the propagating medium and the frequency responses of transmitting and receiving transducers are removed from the former spectrum. RBC aggregation was assessed by the diameter of a scatterer, which was estimated by minimizing the square difference between the measured normalized power spectrum and the theoretical power spectrum. In this study, spherical scatterers with diameters of 5, 11, 15, and 30 µm were measured in basic experiments. The estimated scatterer diameters were close to the actual diameters. Furthermore, the transient change of the scatterer diameters were measured in an in vivo experiment with respect to a 24-year-old healthy male during the avascularization using a cuff. The estimated diameters (12–22 µm) of RBCs during avascularization were larger than the diameters (4–8 µm) at rest and after recirculation. These results show the possibility of the use of the proposed method for noninvasive assessment of RBC aggregation.
Stability of Quantitative Evaluation Method of Liver Fibrosis Using Amplitude Distribution Model of Fibrotic Liver
Authors: Igarashi Yu , Yamaguchi Tadashi , Hachiya Hiroyuki
Published: July 2011

In the clinical diagnosis of liver fibrosis using ultrasound B-mode images, there are some differences between individual doctors' diagnosis results. Hence, the realization of a quantitative diagnosis method using ultrasonic echo signals is strongly required. The probability density function (PDF) of the echo signal envelope is an important factor for ultrasound tissue characterization (TC). To realize the quantitative diagnosis of the stage of liver fibrosis, we proposed an amplitude distribution model using two Rayleigh distributions. We have been studying the possibility of the quantitative estimation of liver fibrosis by using this model. In this paper, we present the evaluation results of liver fibrosis for clinical data using the amplitude distribution model. Then, we present the stability of the quantitative estimation method of liver fibrosis using the amplitude distribution model by a simulation, and compare the results using the simulation and clinical data. Stability evaluation has enabled the estimation of the progress of liver fibrosis considering statistical dispersion.
Experiment on Effect of Screening Hydrophone for Reduction of Flow-Induced Ambient Noise in Ocean
Authors: Lee Seongwook , Kim Seong-Ryul , Lee Yong-Kuk , Yoon Jong Rak , Lee Phil-Ho
Published: July 2011

Experimental results, measured in a shallow sea with tidal current for reducing the flow-induced low-frequency ambient noise, are represented. The hydrophone screened with 3-cm-thick 10 ppi open-cell foam showed the reduction of flow-induced ambient noise up to 24 dB below 50 Hz at the current speed of 56 cm/s. The attenuation of acoustic energy caused by the screen, estimated based on the measurements of ship noise in situ and hydrophone sensitivity in a water tank, is considered to be less than 1 dB at 2–10 kHz band when the thickness of the foam is less than 3 cm.