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Showing papers by "Nagoya Institute of Technology published in 1988"


Journal ArticleDOI
TL;DR: The effects of ArF excimer laser irradiation on dehydrated high-purity silica glass were investigated on both the optical-absorption bands due to oxygen-deficient centers (ODC) and the formation of E- center density, suggesting that there exist two types of ODC: ODC(I), which is responsible for the 7.6-eV band, and ODC (II), for the 5.0- eV band.
Abstract: The effects of ArF excimer laser irradiation on dehydrated high-purity silica glass were investigated on both the optical-absorption bands due to oxygen-deficient centers (ODC) and the formation of ${E}^{\ensuremath{'}}$ centers. With an intense uv flux from an excimer laser, an ${E}^{\ensuremath{'}}$-center density of the order of ${10}^{15}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ was created. The 7.6-eV absorption band remains at the original level, while the 5.0-eV absorption band having the 4.3-eV emission band decreased. Both bands were reduced by heat treatment in an ${\mathrm{O}}_{2}$ atmosphere. These results suggest that there exist two types of ODC: ODC(I), which is responsible for the 7.6-eV band, and ODC(II), for the 5.0-eV band. The concentrations of ODC(I) and ODC(II) were evaluated to be 1 \ifmmode\times\else\texttimes\fi{} ${10}^{18}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ through an analysis of the gas treatment data and of the order of ${10}^{14}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ through the growth curve of the ${E}^{\ensuremath{'}}$ centers, respectively. The structural origin of ODC(I) has been attributed to the Si-Si bond, judging from the fact that the peak energy and cross section of the absorption were in close agreement with those of the ${\mathrm{Si}}_{2}$${\mathrm{H}}_{6}$ molecule. Theoretical calculations on defect energy levels by O'Relly and Robertson supported the structural model for IDC(I) and suggested an unrelaxed oxygen vacancy for ODC(II). These assignments were also consistent with the results of a quenching experiment in which the fictive temperature of samples was changed; the equilibrium between concentrations of ODC(I) and ODC(II) shifted in a reasonable manner.

229 citations


Journal ArticleDOI
TL;DR: In this article, a two-equation level turbulence model is proposed for closed the energy equation, which does not require questionable assumptions for the turbulent Prandtl number, and is tested on a flat-plate boundary layer and the thermal entrance region of a pipe.
Abstract: A new proposal for closing the energy equation is presented at the two-equation level of turbulence modeling. The eddy diffusivity concept is used in modeling. However, just as the eddy viscosity is determined from solutions of the k and {var epsilon} equations, so they eddy diffusivity for heat is given as functions of temperature variance t{sup 2}, and the dissipation rate of temperature fluctuations {var epsilon}{sub t}, together wtih k and {var epsilon}. Thus, the proposed model does not require any questionable assumptions for the turbulent Prandtl number. Modeled forms of the t{sup 2} and {var epsilon} equations are developed to account for the physical effects of molecular Prandtl number and near-wall turbulence. The model is tested by application to a flat-plate boundary layer, the thermal entrance region of a pipe, and the turbulent heat transfer in fluids over a wide range of the Prandtl number. Agreement with the experiment is generally very satisfactory.

208 citations


Journal ArticleDOI
TL;DR: In this article, a detailed hot-wire measurement of a turbulent natural convection boundary layer is made paying close attention to the characteristics of the near-wall region which has not been clarified quantitatively.

188 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated defect formation in dehydrated silica glasses using various excimer lasers with different energies and found that the E' center probably originated from oxygen-deficient centers.
Abstract: Defect formation in dehydrated silica glasses was investigated using various excimer lasers with different energies. The ArF laser (6.4 eV) generates the E’ center more effectively than the KrF laser (5.0 eV), while the XeCl laser (4.0 eV) generated no centers. Defect generation was found to be proportional to the square of the laser photon density, indicating that it occurs dominantly due to a two‐photon process which makes band‐to‐band excitation possible. The E’ center probably originated from oxygen‐deficient centers. Contributions to the E’ center formation from a process involving direct absorption at the sites of intrinsic defects in SiO2 glass were discussed on the basis of the excitation energy dependence and a comparison with the effect of a low‐pressure mercury lamp.

131 citations



Journal ArticleDOI
TL;DR: In this paper, an orthogonal series expansion for the three-dimensional joint probability density function (p.d.f.) is developed using the cumulants and Hermite polynomials.
Abstract: Various types of moments of velocity and scalar fluctuations of the first to the fourth order have been measured and analysed. First, an orthogonal series expansion for the three-dimensional joint probability density function (p.d.f.) is developed using the cumulants and Hermite polynomials. This p.d.f. is found to provide satisfactory predictions for the statistical characteristics, including triple products, of turbulent momentum and scalar transfer. Next, the conditional sampling and averaging technique is employed to investigate the statistical characteristics of coherent turbulent transfer processes of momentum and scalar. Conditional p.d.f.s are developed for various moments of velocity and scalar up to the third order. It is shown that the present p.d.f.s can predict the detailed role of coherent motions in the dynamics of wall turbulent shear flows and in the relevant process of scalar transport by turbulence. In particular, the importance of coherent motions in the turbulent diffusion process of Reynolds-stress components and scalar fluxes is demonstrated for the first time by the present theory.

97 citations


Journal ArticleDOI
TL;DR: In this article, the reliability of Reynolds stress and turbulent heat flux measurements is verified by the excellent agreement with the indirect measurements estimated by integrating momentum and thermal energy equations with measured mean velocity and mean temperature.

97 citations


Journal ArticleDOI
TL;DR: The present investigation enables one to evaluate the protonic conductivity and the activation energy at a unit proton concentration of a given glass specimen from an ir spectrum of the glass plate, respectively.
Abstract: Simple relations between protonic conductivity ($\ensuremath{\sigma}$) and the peak wave number (${\ensuremath{ u}}_{\mathrm{OH}}$) of O-H infrared absorption band, and between activation energy for the electrical conduction and the wave number (${\ensuremath{ u}}_{\mathrm{OH}}$) were found in oxide glasses containing no alkali- and/or transition-metal ions. The present investigation enables one to evaluate the protonic conductivity and the activation energy at a unit proton concentration of a given glass specimen from an ir spectrum of the glass plate, respectively.

92 citations


Journal ArticleDOI
TL;DR: In this article, the effect of fiber waviness on the elastic moduli of flexible composites is investigated theoretically and experimentally, and the constitutive relations for the longitudinal and transverse tensile behavior have been developed for these models.
Abstract: The effect of fiber waviness on the elastic moduli of flexible composites is investigated theoretically and experimentally. The flexible composites examined are composed of con tinuous fibers with sinusoidal waviness in an elastomeric matrix. Both iso-phase and random-phase fiber arrangements are used for this study. The constitutive relations for the longitudinal and transverse tensile behavior have been developed for these models. Tensile tests have been conducted to verify the constitutive relations. Carbon fiber and silicone elastomer were used for the experiments. Techniques for specimen fabrication as well as photoelastic tests are also presented. Experimental results show good agreement with the theoretical predictions.

72 citations


Journal ArticleDOI
02 Oct 1988
Abstract: The authors present a method for the software control of a brushless DC motor using parameter identification. Not only speed and current controls, but also a real-time identification of the motor parameter can be implemented by the software, implemented on the digital signal processor (DSP) TMS320C25. The unique current control is performed according to an instantaneous voltage equation of the d-q model of the motor. The control accuracy depends on the motor parameters, so parameter identification with regard to armature inductance and EMF (electromotive force) constant is necessary. The identification algorithm has been verified by both simulation and experiment. The control program, including parameter identification, is of 2.5 K words, and the processing time is 99 mu s. >

71 citations


Journal ArticleDOI
TL;DR: In this paper, an extensive computer simulation (molecular dynamics) has been done for the calculation of PVT data of Lennard-Jones fluids and their binary equimolar mixture in a wide range of pressures and temperatures.

Journal ArticleDOI
TL;DR: Indium-mediated reformatsky reaction gave good yields of β-hydroxyesters under very mild reaction conditions as discussed by the authors, but it was not suitable for β-carotenoids.

Journal ArticleDOI
TL;DR: In this article, the degree of transportation of beryllium with H2O is measured under the upper mantle P/T conditions in order to examine the incorporation of 10Be in subduction zone magmas.
Abstract: The degree of transportation of beryllium with H2O is measured under the upper mantle P/T conditions in order to examine the incorporation of 10Be in subduction zone magmas. 5.4±0.3% of original beryllium in the starting serpentinite is extracted with H2O from the system through the dehydration reaction of serpentine at 850°C and 1.5 GPa. It follows that the partial melting of oceanic lithosphere including 10Be-rich sediment layer is not necessarily required for inclusion of the isotope in island-arc lavas. We suggest that the dehydration processes in the subducted slab and mantle wedge materials dragged downward by the slab subduction govern the concentration of 10Be in arc lavas.

Journal ArticleDOI
TL;DR: In this article, a mathematical model is developed to predict the transverse elastic moduli of unidirectional fiber composites, where the fiber and matrix materials are assumed to exhibit transverse isotropy, and the elastic interactions among fibers are also considered.
Abstract: A mathematical model is developed to predict the transverse elastic moduli of unidirectional fiber composites. Two cases of fiber/matrix interfacial bondings are investigated: perfect bonding and complete debonding,i.e., no transferring of tensile stress on surfaces where the fiber and matrix materials are separated. Fibers are assumed to exhibit transverse isotropy, and the elastic interactions among fibers are also considered. In the analysis of the completely debonded case, the cavity formation model is adopted and the original fiber and surrounding cavities are replaced by an imaginary anisotropic inclusion. Closed form solutions of effective elastic moduli are obtained for transverse tensile and compressive moduli, and transverse shear moduli. The limiting case of fiber-like voids is also studied. Numerical results are presented for two metal matrix composites, where the optimal wetting between the fiber and matrix is difficult to be obtained and hence the interfacial bonding and transverse property have been major concerns.

Journal ArticleDOI
TL;DR: Oxygen nonstoichiometry of the YBa2Cu3O7-x phase has been determined for between 200 to 850°C and oxygen partial pressure of 10 to 30×10-4 atm by thermogravimetric measurements.
Abstract: Oxygen nonstoichiometry of the YBa2Cu3O7-x phase has been determined for between 200 to 850°C and oxygen partial pressure of 10 to 30×10-4 atm by thermogravimetric measurements Values of the partial molar enthalpy of oxygen were estimated The stable region of the orthorhombic phase was suggested to expand at lower temperatures

Journal ArticleDOI
TL;DR: In this paper, a widely spaced comb-like polymers with side-chains with teeth appeared on every four main-chain carbon atoms were synthesized as copolymers of styrene, or α-methylstyrene with alkyl acrylates.
Abstract: Widely spaced comb-like polymers in which teeth (alkyl side-chains) appear on every four main-chain carbon atoms were synthesized as copolymers of styrene, or α-methylstyrene with alkyl acrylates, alkyl methacrylates, or dialkyl itaconates. Alkyl groups were dodecyl, tetradecyl, hexadecyl, and octadecyl. The long alkyl side-chains of these comb-like polymers crystallized as in conventional comb-like polymers but the extent of crystallization varied with cumulative substitution of phenyl and methyl groups on the copolymer main-chains. This is due to the influence of these substituents on the flexibility of the main-chain.

Journal ArticleDOI
TL;DR: A large part of the response from catfish retinal neurons evoked by a white-noise modulated light stimulus is reconstructed by the linear and the second-order nonlinear components, which shows that the first- and second- order kernels represent the major response characteristics.
Abstract: A large part of the response from catfish retinal neurons evoked by a white-noise modulated light stimulus is reconstructed by the linear and the second-order nonlinear components, which shows that the first- and second-order kernels represent the major response characteristics In catfish retina, amacrine cells are classified as type-C and type-N cells Type-C cells produce a stable and stereotyped second-order kernel that can be reproduced by squaring an underdamped first-order kernel This is a linear filter followed by a static nonlinearity and is modeled by a cascade of the Wiener structure A second-order kernel from the other class of amacrine cells, type-N cells, is reproduced by a simple linear filtering of type-C cell response This is a static non-linearity sandwiched between two linear filters and is modelled by a cascade of the Korenberg structure These findings may greatly simplify future attempts to reconstruct retinal circuitry and may give some insight into the process of complex signal processing in the inner part of the vertebrate retina

Journal ArticleDOI
TL;DR: In this paper, the laminar-turbulent transition of the Taylor-Gortler (TG) vortex flow in the clearance between two concentric spheres with only the inner sphere rotating (spherical Couette flow) is investigated by velocity measurement and simultaneous spectral and flow-visualization measurements by measuring the intensity of light scattered by the aluminium flakes used in flow visualization in the case of a relatively small ratio of the clearance to inner-sphere radius (clearance ratio β = 0.14).
Abstract: The laminar—turbulent transition of the Taylor—Gortler (TG) vortex flow in the clearance between two concentric spheres with only the inner sphere rotating (spherical Couette flow) is investigated by velocity measurement and simultaneous spectral and flow-visualization measurements by measuring the intensity of light scattered by the aluminium flakes used in flow visualization in the case of a relatively small ratio of the clearance to inner-sphere radius (clearance ratio β = 0.14). An azimuthal velocity component has been measured by a constant-temperature hotwire anemometer at two different colatitudes (meridian angles) θ; θ = 80° and 90° (the equator). A critical Reynolds number, some transition Reynolds numbers, flow regimes and flow states are obtained by the simultaneous spectral and flow-visualization measurements. The flow state is expressed by the number of toroidal TG vortex cells N, that of spiral TG vortex pairs Sp, the wavenumber of the travelling azimuthal waves on the toroidal TG vortices m and the wavenumber of shear waves SH. The mean velocity distribution and the characteristic values of the fluctuating velocity, such as autocorrelation coefficient, power spectrum and turbulence intensity (r.m.s. value), are considered over a great range of Reynolds number Re. Three kinds of fundamental frequencies of the velocity fluctuation are discovered and their characteristics are clarified by means of the velocity measurement and the simultaneous spectral and flow-visualization measurements. The three kinds of fundamental frequencies expressed by fS, fW and fH correspond to the spiral TG vortices, the travelling azimuthal waves and the shear waves, respectively. These fundamental frequencies are independent of both θ and wall distances from the inner sphere, but depend strongly on Re. Although the rotation frequency of the travelling azimuthal waves (or wave speed) in the circular Couette flow decreases monotonically with increasing Reynolds number until it reaches a plateau, the values of the rotation frequencies of the spiral TG vortices, the travelling azimuthal waves and the shear waves in the spherical Couette flow, fS/SP, fW/m and fH/SH, are nearly constant as the Reynolds number is increased, and differ slightly from one another.

Proceedings ArticleDOI
12 Feb 1988
TL;DR: A new type of high speed range finder system that is based on the principle of triangulation range-finding, with a novel custom range sensor consisting of a 2D array of discrete photo-detectors attached to an individual memory element.
Abstract: We present a new type of high speed range finder system that is based on the principle of triangulation range-finding. One of the unique elements of this system is a novel custom range sensor. This sensor consists of a 2D array of discrete photo-detectors. Each photo-detector is attached to an individual memory element. A slit-ray is used to illuminate the object which is then imaged by the sensor. The slit-ray is scanned at a constant angular velocity, so elapsed time is a direct function of the direction of the slit source. This elapsed time is latched into each individual memory element when the corresponding detector is triggered. The system can acquire the basic data required for range computation without repeatedly scanning the sensor many times. The slit-ray scans the entire object once at high speed. The resulting reflected energy strip sweeps across the sensor triggering the photo-detectors in succession. The expected time to acquire the data is approximately 1 millisecond for a 100x100 pixel range data. The sensor is scanned only once at the end of data acquisition for transferring the stored data to a host processing computer. The range information for each pixel is obtained from the location of the pixel and the value of time (direction of the slit source) stored in the attached memory element. We have implemented this system in an abbreviated manner to verify the method. The implementation uses a 47 x 47 array of photo-transistors. Because of the practical difficulty of hooking up the entire array to individual memories and the magnitude of the hardware involved, the implementation uses only 47 memories corresponding to a row at a time. The sensor is energized a row at a time and the laser scanned. This yields one row of data at a time as we described before. In order to obtain the whole image, we repeat this procedure as many times as we have rows, i.e, 47 times. This is not due to any inherent limitation of the method, but due to implementational difficulties in the experimental system. This can be rectified when the sensor is emitted to custom VLSI hardware. The time to completely obtain a frame of data (47 x47) is approximately 80 milliseconds. The depth measurment error is less than 1.0%.


Journal ArticleDOI
TL;DR: In this article, an infinite plate with a cracked circular hole under uniform heat flux in any direction was analyzed for thermal stress, heat flux, and temperature distributions. And the closed solutions were obtained for the temperature and thermal stress analyses.
Abstract: Analyses of thermal stress, heat flux, and temperature distributions are carried out for an infinite plate with a cracked circular hole under uniform heat flux in any direction. The stress intensity factor and the singularity of the heat flux at the crack tip are also obtained. The rational mapping function and the dislocation method are used for the analyses. The closed solutions are obtained for the temperature and thermal stress analyses.

Journal ArticleDOI
TL;DR: In this paper, the authors present des comportements caracteristiques lors du grossissement: dedoublement des precipites, tres faible vitesse de grossissements, deceleration de la vitese degrossissement for une taille donnee, variations de la fonction de distribution de la taille avec la tail-le des particules and the fraction volumique des precipite.
Abstract: Presentation des comportements caracteristiques lors du grossissement: dedoublement des precipites, tres faible vitesse de grossissement, deceleration de la vitesse de grossissement pour une taille donnee, variations de la fonction de distribution de la taille avec la taille des particules et la fraction volumique des precipites. Explication de ces phenomenes par le diagramme de bifurcation donnee theoriquement sur la base de l'energie totale de la microstructure


Journal ArticleDOI
TL;DR: The structure of physalin M, isolated from Physalis alkekengi var. francheti was determined as 7-deoxyphysalin L by spectroscopic studies and chemica correlation with a known compound as mentioned in this paper.
Abstract: The structure of physalin M, isolated from Physalis alkekengi var. francheti was determined as 7-deoxyphysalin L by spectroscopic studies and chemica correlation with a known compound. Physalin M exhibitec weak cytotoxicity against tumor cells.

Journal ArticleDOI
TL;DR: In this article, the allylation of aldehydes and ketones with allyl iodide was studied and α, β-Unsaturated carbonyl compounds underwent only 1,2-addition.
Abstract: Gallium metal readily prompted the allylation of aldehydes and ketones with allyl iodide. α, β-Unsaturated carbonyl compounds underwent only 1,2-addition.


Journal ArticleDOI
TL;DR: The thermal reactions of hydrated hexagonal RPO4·nH2O (R=Tb or Dy, n=0.5 to 1) were studied at 20° to 1800°C in air under atmospheric pressure as discussed by the authors.
Abstract: The thermal reactions of hydrated hexagonal RPO4·nH2O (R=Tb or Dy, n=0.5 to 1) were studied at 20° to 1800°C in air under atmospheric pressure. The hydrated hexagonal forms were dehydrated at 180° to 250°C. Thereafter, no significant changes in structure were seen up to 800°C (R=Tb) or 700°C (R=Dy). The water corresponding to nH2O was zeolitic water. Anhydrous hexagonal RPO4 gradually transformed into the monazite structure at 900°C (R=Tb) or 800°C (R=Dy), then into the xenotime structure at temperatures above 1100°C (R=Tb) or 900°C (R=Dy).

Journal ArticleDOI
Tetsuo Soga1, Y. Kohama1, K. Uchida1, M. Tajima1, T. Jimbo1, M. Umeno1 
TL;DR: In this article, GaP and GaAs are characterized by double crystal X-ray diffraction, photoluminescence and transmission electron microscopy and the thermal cycle growth is employed for GaAs on Si to reduce the dislocation density.

Journal ArticleDOI
TL;DR: In this paper, the problem of partitioning students into groups from both the viewpoints of the students and the laboratories is considered and a method which incorporates new procedures into the MODI method for solving the transportation problem is proposed.

Journal ArticleDOI
TL;DR: In this article, the structure of the 1-butadienyloxytrimethylsilane (BdTMS) was revealed by NMR and IR analyses as 1,4-trans addition mode of diene.
Abstract: As requirement for the synthesis of new C4-type periodic polymers, group transfer polymerization of 1-butadienyloxytrimethylsilane (BdTMS) was examined. Equimolar Benzaldehyde (BAld)–ZnCl2 catalysts in benzene at 20°C were effective to give a soluble polymer in organic solvents. The structure of the polymer was revealed by NMR and IR analyses as 1,4-trans addition mode of diene. Dispersities (Mw/Mn) of molecular weight distribution evaluated by GPC reduced to about 1.5, clearly differing from about 3 in the case of ZnCl2 alone. SnCl4 or (C2H5)3Al2Cl3 without BAld polymerized BdTMS rapidly, accompanying gelation even at −78°C. Living propagation in BdTMS/BAld/ZnCl2 system was confirmed by the incremental monomer addition method. In NMR-monitoring the equimolar reaction of BdTMS/BAld catalyzed by ZnCl2 in C6D6, it was found that an aldol adduct appeared at the first stage and then a formyl group regenerated in the adduct began to react with the monomer.