Showing papers by "Japan Atomic Energy Research Institute published in 1995"
TL;DR: This model describes single-lane traffic flow on a ring and generalizes the asymmetric exclusion process models and calculates the so-called fundamental diagrams (flow vs. density) for parallel dynamics by means of an improved mean-field approximation.
Abstract: We investigate a probabilistic cellular automaton model which has been introduced recently. This model describes single-lane traffic flow on a ring and generalizes the asymmetric exclusion process models. We study the equilibrium properties and calculate the so-called fundamental diagrams (flow versus density) for parallel dynamics. This is done numerically by computer simulations of the model and by means of an improved mean-field approximation which takes into account short-range correlations. For cars with a maximum velocity of 1, the simplest nontrivial approximation gives the exact result. For higher velocities, the analytical results, obtained by iterated application of the approximation scheme, are in excellent agreement with the numerical simulations.
420 citations
TL;DR: A model based on quantum molecular dynamics incorporated with a statistical decay model (SDM) to describe various nuclear reactions in a unified way is proposed and a unified description of the three major reaction mechanisms, i.e., compound, preequilibrium, and spallation processes, is given.
Abstract: We propose a model based on quantum molecular dynamics (QMD) incorporated with a statistical decay model (SDM) to describe various nuclear reactions in a unified way. In this first part of the work, the basic ingredients of the model are defined and the model is applied systematically to the nucleon- (N-)induced reactions. It has been found that our model can give a remarkable agreement in the energy-angle double differential cross sections of (N,${\mathit{xN}}^{\ensuremath{'}}$) type reactions for incident energies from 100 MeV to 3 GeV with a fixed parameter set. A unified description of the three major reaction mechanisms of (N,${\mathit{xN}}^{\ensuremath{'}}$) reactions, i.e., compound, preequilibrium, and spallation processes, is given with our model.
316 citations
TL;DR: In this paper, the irradiation effect of polytetrafluoroethylene (PTFE) was examined by tensile test and thermal analysis in a wide range of irradiation temperature.
190 citations
TL;DR: The thermal ellipsoids also show large anisotropies, which correlate strongly with the directions of the movements of oxygen ions during the phase transition, and all positional parameters of the monoclinic phase approach those of the tetragonal structure.
Abstract: High-resolution neutron-diffraction experiments have been performed to study the structural changes of ${\mathrm{ZrO}}_{2}$ induced by ${\mathrm{CeO}}_{2}$ doping. The crystal structures of monoclinic [P${2}_{1}$/c, Z=4] and tetragonal [P${4}_{2}$/nmc, Z=2] phases for ${\mathrm{ZrO}}_{2}$--X mol % ${\mathrm{CeO}}_{2}$ (X=0, 2, 5, 8, 10, 12, and 15) have been refined by the Rietveld analysis of the diffraction patterns measured at 298 K. The unit-cell parameters change anisotropically with an increase of ${\mathrm{CeO}}_{2}$ content X. In the monoclinic phase ${\mathit{a}}_{\mathit{m}}$ and ${\mathit{c}}_{\mathit{m}}$ increase considerably while ${\mathit{b}}_{\mathit{m}}$ shows a rather small increase with increasing X where the suffix m denotes the monoclinic phase. The angle ${\mathrm{\ensuremath{\beta}}}_{\mathit{m}}$ decreases with increasing X. The thermal ellipsoids also show large anisotropies, which correlate strongly with the directions of the movements of oxygen ions during the phase transition. The unit-cell parameters and the atomic positions discontinuously change during the monoclinic-tetragonal phase change. The crystal structure of monoclinic phase approaches that of tetragonal phase with an increase of X: (1) the length of ${\mathit{a}}_{\mathit{m}}$ approaches that of ${\mathit{b}}_{\mathit{m}}$ with increasing X, (2) the angle ${\mathrm{\ensuremath{\beta}}}_{\mathit{m}}$ decreases with X, and (3) all positional parameters of the monoclinic phase approach those of the tetragonal structure.
123 citations
TL;DR: In this paper, the pore surface of a porous hollow-fibre membrane was used to collect proteins at a high rate and high capacity because of convective transport and multi-layering of proteins.
118 citations
TL;DR: In this paper, the behavior of an intermetallic compound ZrCo with hydrogen at high temperature region was studied with respect to application utilizing the reversible hydrogenation, and the results suggest some operational precaution and limitation, and recovery treatment when the material is suspected to have lost some capacity by disproportionation reaction.
95 citations
TL;DR: The results suggest that the main part of conformation- dependent antigenic structure (conformational epitope) is easily lost by radiation, but some antigenicity, which is mostly due to the amino acid sequence-dependent antigenic structures (sequential epitopes), remains even at higher dose.
87 citations
TL;DR: The experimental results for angle-differential cross sections are well reproduced by exact relativistic calculations which yield significant deviations from standard sin[sup 2][theta] distributions, and lends support to the use of the nonrelativistic approach for practical purposes.
Abstract: The process of radiative electron capture (REC) in relativistic collisions of high-Z ions with low-Z gaseous and solid targets is studied experimentally and theoretically. The observed x-ray spectra are analyzed with respect to photon angular distributions as well as to total K-REC cross sections. The experimental results for angle-differential cross sections are well reproduced by exact relativistic calculations which yield significant deviations from standard ${\mathrm{sin}}^{2}$\ensuremath{\theta} distributions. Total cross sections for K-REC are shown to follow a simple scaling rule obtained from exact relativistic calculations as well as from a nonrelativistic dipole approximation. The agreement between these different theoretical approaches must be regarded as fortuitous, but it lends support to the use of the nonrelativistic approach for practical purposes.
70 citations
TL;DR: Saltelli et al. as discussed by the authors proposed two new sensitivity analysis techniques, modified Hora and Iman importance measure (HIM^*) and the iterated fractional factorial design (IFFD) to overcome limitations in existing methods.
67 citations
TL;DR: In this article, a model of the lysozyme crystallization process was given by time-resolved small angle neutron scattering from Lysozyme in supersaturated solution, where larger aggregates (Type I), with a radius greater than several hundred angstrom, co-exist with a much larger number of smaller particles (Type II), the radius of which is between 25 and 40 A.
65 citations
TL;DR: In this paper, the pyrolysis reaction mechanisms from the organic PCS to ceramic SiC were investigated by the analysis of gases evolved during heat treatment, and the first step was at 800-1,200 K where H{sub 2} and CH{sub 4} evolved by scission of Si-CH{sub 3} and Si-H and by rearrangement reactions.
Abstract: SiC fibers were synthesized from polycarbosilane (PCS) fibers by heat treatment after electron beam irradiation curing. The pyrolysis reaction mechanisms from the organic PCS to ceramic SiC were investigated by the analysis of gases evolved during heat treatment. There were two steps in the major reaction: the first step was at 800--1,200 K where H{sub 2} and CH{sub 4} evolved by scission of Si-CH{sub 3} and Si-H and by rearrangement reactions, and the second step was at 1,000--1,700 K where H{sub 2} evolved by reactions related to C atoms in the PCS main chain. H{sub 2} evolution in the first step was reduced with increasing oxygen content in the cured PCS fibers.
TL;DR: In this article, the authors investigated the suitability of lithium-containing ceramics for tritium breeding materials for fusion reactor blankets, particularly because of their safety advantages and compatibility with structures and beryllium.
TL;DR: In this article, a luminescence study of Ln(III) ion has revealed a linear correlation between the decay constant kobs (the reciprocal of the excited-state lifetime) and the number of water molecules nH2O in the first coordination sphere of complexes.
TL;DR: In this article, the release behavior of fission products from ZrC-coated UO 2 particles was studied by a postirradiation heating test at 1600°C (1873 K) for 4500 h and subsequent postheating examinations.
TL;DR: In this paper, the scattered energy spectra of monochronized synchrotron-radiation photons were measured using high-purity Ge detectors to obtain incoherent scattering function (S) in the 1.14x2.28-A$
Abstract: The scattered-energy spectra of monochronized synchrotron-radiation photons toward 90\ifmmode^\circ\else\textdegree\fi{} by C, Al, Fe, Cu, Au, and Pb samples were measured using high-purity Ge detectors to obtain incoherent scattering function (S) in the 1.14x2.28-A${\mathrm{\r{}}}^{\mathrm{\ensuremath{-}}1}$ region. The multiple-scattering intensity was evaluated by a Monte Carlo calculation while considering the Doppler broadening of the Compton-scattered photons and the photon linear polarization. The measured S of C, Al, Fe, and Cu agreed with that based on the Waller-Hartree theory (${\mathit{S}}^{\mathit{W}\mathit{H}}$), as well as that based on a relativistic impulse approximation (${\mathit{S}}^{\mathit{I}\mathit{A}}$) within the experiment error (2.5%). The measured S of high-Z atoms (Au and Pb) agrees with ${\mathit{S}}^{\mathit{I}\mathit{A}}$ and is smaller than ${\mathit{S}}^{\mathit{W}\mathit{H}}$ by 3--6 %.
02 Sep 1995-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: The JAERI light-ion microbeam apparatus for high-resolution ion beam analysis was constructed and installed on a beam line of 3 MV single-ended electrostatic accelerator with a high voltage stability of ± 1 × 10−5 as mentioned in this paper.
Abstract: The JAERI light-ion microbeam apparatus for high-resolution ion beam analysis was constructed and installed on a beam line of 3 MV single-ended electrostatic accelerator with a high voltage stability of ± 1 × 10−5. In a performance test of the apparatus, the spot size of 0.4 × 0.4 μm2 in FWHM has been achieved so far by using 2 MeV helium ion beam with a target beam current of 77 pA. The light-ion microbeam apparatus and the accelerator system and the beam size measurement using 2 MeV helium ions is described. The ion beam optical design for submicron microbeam is also discussed.
TL;DR: In this article, the negative-ion-based neutral beam injection (NBI) system for JT-60U has been proposed and shown to demonstrate a mega-amp level NB current drive at high plasma density and to study high energy beam heating in reactor-grade plasmas.
TL;DR: In this paper, a polymer chain containing a diethylamino group was grafted onto the pore surface of a porous hollow-fiber membrane by radiation-induced graft polymerization.
TL;DR: In this paper, the authors investigated the synergistic extraction of trivalent lanthanides using thenoyltrifluoroacetone (HTTA) and crown ether (CE).
Abstract: Synergistic extraction of trivalent lanthanides(Ln) was investigated using thenoyltrifluoroacetone(HTTA) and crown ether(CE). Characteristic ion-pair extraction of the lighter Ln(III) was observed with 1,2-dichloroethane containing HTTA and 18-crown-6 or dicychlohexano-18-crown-6, in which the cationic complex, Ln(TTA)2CE+, was formed and extracted. Remarkable increases of an extractability and a selectivity were attained in the synergistic ion-pair extraction of the lighter Ln ions, which could be elucidated on the basis of size-fitting effect in the complex formation of the lighter Ln ions with CE.
TL;DR: In this article, a series of experiments to investigate melt-coolant interactions have been performed as part of the ALPHA program at JAERI, where melt simulating a molten core was dropped into a pool of water and volume fractions of the melt, water and steam in the mixing region prior to the occurrence of spontaneous steam explosions were quantified.
TL;DR: In this paper, six methods were used to evaluate the heat resistance of polyvinyl alcohol (PVA) hydrogel prepared by a combination of electron beam irradiation and acetalization of PVA.
TL;DR: In this article, the de Haas-van Alphen (dHvA) oscillation in both the normal and superconducting mixed states of CeRu 2 was observed.
Abstract: We have observed the de Haas-van Alphen (dHvA) oscillation in both the normal and superconducting mixed states of CeRu 2 . The dHvA amplitude in the mixed state is extremely reduced for the large cyclotron orbit or the carrier with a large cross-sectional area of the Fermi surface compared to the small one. We have detected three dHvA branches, ranging from 6×10 5 Oe to 2.3×10 7 Oe. The origin of these branches is well explained by the 4 f -itinerant band model.
TL;DR: In this article, butylacetate and xylene were irradiated with electron beam in the dose range of 0-10 kGy at ambient temperature and the removal efficiencies measured by FID and gas chromatography.
TL;DR: In this paper, the melting points of the fractionated samples showed pseudoeutectic changes with minimum breaking point at ca. 30 mol% 3HV, and the crystal lattice of the copolymer was of either P(3HB)-co-3HV type depending on whether the 3-HV composition was lower or higher than this range, respectively.
TL;DR: In this paper, the 1987 evaluation for A=118 moss chain (87Ta12) has been revised using experimental decoy and reaction data available before November 1992 for nuclides 118 Pd and 118 Ag data published until February 1993 have been used.
TL;DR: Graft copolymerization of methyl methacrylate (MMA) or 2-hydroxyethyl methacelate (HEMA) onto poly(3-hydroxbutyrate) (PHB) and its copolymers was carried out by using simultaneous radiation and pre-radiation techniques from a 60Co γ-rays source as discussed by the authors, and the degree of grafting (X g) of MMA onto both polymers increased as the irradiation dose increased.
Abstract: Graft copolymerization of methyl methacrylate (MMA) or 2-hydroxyethyl methacrylate (HEMA) onto poly(3-hydroxybutyrate) (PHB) and its copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) {P(HBHV)} was carried out by using simultaneous radiation and preirradiation techniques from a 60Co γ-rays source. Degree of grafting (X g) of MMA onto both polymers increased as the irradiation dose increased. The X g for PHB graft-polymerized by simultaneous radiation was lower than that for the copolymer of 24 mol% HV content (24 M sample). On the contrary, X g of PHB graft-polymerized after preirradiation was higher than that of the 24 M sample. The X g depended on differences in regularity in the crystalline regions or crystallinity and rate of radical decay. Crystalline regions of PHB remained almost unchanged after grafting, while crystalline regions of the 24 M sample were partially destroyed by the introduction of grafting. Glass transition temperatures of both grafted polymers increased up to 8°C. The ...
TL;DR: In this article, the local transport analysis of JT-60U plasmas has been carried out for NBI heated L-mode phase, and the properties of the one fluid thermal diffusivity, χ eff, χ e, the electron thermal diffusion and the ion thermal diffusion have been compared.
Abstract: Nondimensional local transport analysis of JT-60U plasmas has been carried out for NBI heated L-mode phase. Plasmas with the same poloidal cross section and almost the same profiles of nondimensional parameters such as ν * , β th , q , T e / T i except for ρ * are compared. The ρ * dependence of the one fluid thermal diffusivity, χ eff , the electron thermal diffusivity, χ e , and the ion thermal diffusivity, χ i , has been examined. The property of χ eff is between the weak gyroBohm type diffusion and the Bohm type diffusion in the region a /3≤ r ≤2 a /3, which is consistent with the results of the global confinement study done before. We have also found that χ e is weak gyroBohm type diffusion while χ i tends to be Bohm like diffusion.
TL;DR: In this paper, a novel porous membrane was prepared by radiation-induced graft polymerization of an epoxy-group-containing vinyl monomer, glycidyl methacrylate, and subsequent addition of phenol and water.
TL;DR: In this article, a toroidal asymmetry factor of 2.5 is estimated from the requirements of the fracture of the carbon-fiber composite tiles in the JT-60U tokamak.
Abstract: A poloidal halo current due to a vertical displacement event (VDE) is observed in experimentally simulated VDE discharges and density limit disruptions in the JT-60U tokamak. In the case of a clockwise I{sub p} and B{sub T} discharge, the halo current flows into the vacuum vessel from the inside separatrix and goes back to the plasma from the outside separatrix. A maximum halo current is produced by a change in the poloidal flux generated by plasma current decay. A toroidal asymmetry factor of 2.5 is estimated from the requirements of the fracture of the carbon-fiber composite tiles. The toroidal asymmetry is caused by the poloidal field (PF) that is produced by the toroidal field (TF) ripple, the deformation of the vacuum vessel, the setting error between the vacuum vessel and the TF and PF coils, the low-n mode during current quench, etc. To consider this asymmetry, in JT-60U, one must estimate the total halo current as nearly 26% of the plasma current just before a current quench. 25 refs., 10 figs.