K-edge X-ray absorption fine structures of oxides, carbide and nitrides of rare earth elements (Ce, Pr, Nd, Gd and Tb) were measured by use of the beamline BL01B1 in SPring8. Significant chemical shifts of the edge energy were detected. Spectra worth being analized by an ordinary EXAFS method were obtained and the results of EXAFS analyses were in excellent agreement with those of XRD.
A finite element method (FEM) analysis has been performed to evaluate the low cycle fatigue life of the surface modified low carbon steel by quenching and tempering treatment. It was found that the equivalent plastic strain range of the surface modified steel, which has modifying layer with a thickness of 0.5mm, was smaller than that of non-surface modified steel at the surface portion of the specimen. The low cyde fatigue life appears to be improved by the surface treatment.
This paper discusses the differences among the directional fracture criteria, based on the directional fracture approach (DFA). These criteria are the directional maximum circumferential tensile stress criterion (σ θ ), directional maximum square circumferential tensile stress criterion (σ 2 θ ), directional maximum energy release rate criterion (G), directional minimum total strain energy density criterion (S) and directional volumetric-distortion strain energy density criterion (S VD ). The comparisons include the hypotheses of all criteria, mechanisms, critical fracture directions, critical fracture loads, critical fracture increments, final propagation paths and critical stress intensity factors. The current criteria already recorded the best results against the old theories for cracks of isotropic materials in linear elastic fracture mechanics LEFM under both tension and compression. The comparisons are made mainly to determine the best methods in applying these criteria to different types of crack modes through a new treatment considering the mechanism conditions of the cracking process.
Some states in a sequential circuit can not be reached by any input sequence. A state is said to be unreachable if it has no transition from any other state. A test generator wastes a time if tries to bring a state of a circuit to an unreachable state. Therefore the information about unreachable states in the circuit is useful for reducing test generation time. We have reported that obtaining strongly unreachable states, which are part of unreachable states, is useful to simplify the sequential circuit. In this paper, we present a procedure to identify strongly unreachable states for the circuit which is described by the gate-level and whose state transition table is not given. The input functions of flip-flops are used to identify the invalid combination of state values. Since the procedure to identify unreachable states requires large memory for the circuits with many flip-flops, we also present a procedure to partition the set of flip-flops in order to restrict the number of flip-flops. Experimental results for benchmark sequential circuits show the effectiveness of the proposed procedure.
The phases of iron nitride nanograins dispersed in a silver matrix were determined by Fe-K edge X-ray absorption near edge structure (XANES) method, which overcame difficulties caused by the ultrafine grain size and the shielding effect of the matrix. The two phases of γ'-Fe 4 N and e-Fe 2-4 N were clearly distinguished by comparing their XANES spectra with those of reference materials well characterized by XRD.
Extremely low cycle fatigue (ELCF) tests were carried out at room temperature under the strain controlled condition on the notched low carbon steel specimens with root radii of 20, 2 and 0.4 mm, which were denoted as R20, R2 and R0.4 series respectively. The fracture mode transition that crack initiation site changes from the surface to the internal of the specimen with increasing the applied plastic strain range was found to occur in R20 series. In R2 and R0.4 series, not the fracture mode transition but the surface cracking fracture mode was observed. In order to elucidate the reason why the fracture mode transition occurred, dominant factors for ELCF properties were considered. Based on the Coffin's theoretical concept, it is assumed that ELCF properties are evaluated by the value of equivalent plastic strain range (Δ e Peq ) where fracture occurs, which is estimated by finite element method (FEM) analysis. As a result of applying the assumption to the fatigue test results, the assumption would be valid to the fracture mode transition and fatigue life evaluation. It is concluded that the value of Δ e Peq where fracture occurs is the dominant factors for ELCF properties.
The average thermal expansion coefficient of UFe 2 was estimated from the high temperature X-ray diffraction, and the heat capacity of UFe 2 was evaluated with the thermal expansion data, the Debye temperature and the bulk modulus. The changes in the longitudinal sound velocities in UFe 2 , UNi 2 , URu 3 , URh 3 , UPd 3 and UNi 5 with temperature were measured by an ultrasonic pulse-echo method. The temperature dependence of the Young's, shear and bulk moduli in the intermetallic compounds was estimated from the sound velocities. The elastic moduli decreased as the temperature increased, except for UFe 2 .
From the experience of the serious damages of concrete piers due to the Great Hanshin Earthquake, the strengthening for the existing concrete piers against such a large earthquake has become a more important maintenance work. By strengthening, both the ductility and the flexural strength of the strengthened pier must be well increased. In this paper, a strengthening method for concrete piers using partial concrete lining jacket covered by carbon fiber sheets is investigated. The test specimens are loaded statically with alternating horizontal bads. A total of 11 specimens are loaded until failure. The results show that the combination of the partial concrete lining and the carbon fiber sheet covering in the hoop direction improves both of the load carrying capacity and the ductility of RC piers.
DNA computing is a novel method of computing proposed by L. M. Adleman [Science 266 (1994) 1021], in which the data is encoded in the sequences of oligonucleotides. Massively parallel reactions between oligonucleotides are expected to make it possible to solve huge problems. In this study, reliability of the ligation process employed in the DNA computing is tested by estimating the error rate at which wrong oligonucleotides are ligated. Ligation of wrong oligonucleotides would result in a wrong answer in the DNA computing. The dependence of the error rate on the number of mismatches between oligonucleotides and on the combination of bases is investigated.
GaAs is treated with PH 3 and N 2 plasmas. Electron traps induced by these plasma treatments are investigated by isothermal capacitance transient spectroscopy. The EL2 trap (E C -0.86eV) is detected in the as-grown GaAs. On the other hand, electron traps induced in phosphidized and nitridated GaAs are designated as the T P1 trap (E C -0.26eV) and the T N1 trap (E C -0.66eV), respectively. It is found that the T P1 trap is changed to another trap with an energy level as shallow as 0.16eV below the conduction band edge and a capture cross section as small as 1.8 X 10 -21 cm 2 by treating with N 2 plasma subsequently after PH 3 plasma treatment.
The linear thermal expansion coeffident, the compressibility, and the molar specific heat of UO 2 were studied by a molecular dynamics (MD) technique in the temperature range of 300-1600K. The Morse-type potential function added to the Busing-Ida type potential was used. The calculated linear thermal expansion coefficient was lower than almost all the values of experimental data, but is found to increase with temperature similar to the real uranium dioxide. The calculated compressibility was slightly higher than that of the experimental data, but increased with temperature rise. This means that the MD cell becomes soft by rising temperature similar to the real material. The calculated molar specific heat of UO 2 at the constant pressure agreed with those of the experimental data at high temperatures. This result indicates that the potential function used in the present study well describes the change in the internal energy of UO 2 with temperature. From these results, the molecular dynamics calculation is applicable to evaluate the thermal properties of UO 2 .
Sulfur-doped boron nitride (BN) films have been grown by plasma-assisted chemical vapor deposition (PACVD) method. Fourier transform infrared absorption (FTIR) spectra with absorption band at 800cm -1 and 1380cm -1 suggest deposition of hexagonal BN (h-BN). The electrical resistivity is estimated to be 4.9× 10 2 Ωcm and optical energy bandgap is evaluated to be 5.9eV from the absorption spectrum measured in the ultraviolet-visible region. The electron emission occurs at an electric field as low as 10V/ μm for the S-doped BN film. It is found that no degradation of this value occurs for the BN film treated with O 2 plasma for 15min.
Fusion pellet implosion by direct laser irradiation was investigated by means of time- and space-resolved spectroscopic measurements. Deuterium fuel gas was seeded with a small amount of Ar in order to observe influence of temporal variation of argon line emissions and their spatial extent on low modal non-uniformity imposed artifidally by changing a pellet irradiation condition. The experimental results were compared with two-dimensional hydro-code simulations, which were post-processed with an X-ray spectrum analysis code. The experimental results for a focal condition d/R = - 4 (d is the distance between the focus point and the center of pellet with radius R) were well replicated when a velocity perturbation of 20 percent of the average is supplied for the mode number 6, whereas those for the d/R=-3 showed earlier appearance of the Ar line emissions than the simulations. These results are examined in terms of shell breaking due to the low-modal non-uniformity.
The multiband method was applied to S n method in order to analyze the reaction rate distributions in the blanket region of a fast reactor. The multiband S n formulation led to the direction dependence in total cross sections, with which the difference in the penetration rate for each direction was considered. As a test calculation, the U-238 capture rate distribution in a prototype fast reactor was calculated. The reaction rate in the blanket region obtained from the present method became larger than the commonly used multigroup method by 2% at maximum. The present result shows the same tendency as the continuous energy Monte Carlo method.
Many measurements of daylight and solar radiation have been carried out at many stations in the world since 1991. For the speedy processing of a large volume of observed data, it is essential to establish a moderate method to calculate the sun position. In order to identify the accurate position of the moving sun, it is necessary to refer to the values of the sun declination and the equation of time. In this paper, regression equations which derive the sun declination and the equation of time as a function of mean solar time are developed according to the principle of the sun movement on a celestial sphere. They include two astronomical constants; the one revolution year ( = 365.2422 days) and the inclination of the axis of the earth (= 23.439 degree).
An improved correlated sampling method was developed. By using this method, the reactivity can be correctly evaluated compared with the conventional method, because the change of the neutron source distribution caused by the perturbation is taken into consideration in the improved method. Both the conventional and the improved methods were introduced into a continuous energy Monte Carlo code. Through the numerical tests, was found that the two methods give reasonable results even in a case of a small perturbation, and there is a small effect of using the improved correlated sampling method at least in the range of our calculations.
Magnetoresistance has been measured in InAs/AlGaSb quantum wells and wires. Weak oscillatory structures due to magnetophonon effects have been observed for N = 1 and N= 2 resonances. The resonance magnetic field for N=2 in quantum wires is found to be lower than that in quantum wells, which is attributed to the effects of high electron density and asymmetric density of states in quasi-one-dimensional systems.
Beam quality : To increase the filling factor of a laser beam pattern, avoiding generation of high spatial-frequencies, we intend to use serrated aperture for which we optimized the shape. This paper starts with a theoretical approach of the serration effects. This study has given us the method to reach very high filling factor up to 86% with less than 2 % contrast on the laser intensity pattern.
Monte Carlo simulation for one- and two-dimensional electron channel formed in GaAs/AlGaAs heterojunction is performed to study how the drift-velocity depends on the dimensionality of electrons. The electronic states are evaluated via the self-consistent calculation. For evaluating the drift-velocity, only electronlongitudinal-optical-phonon scattering is taken into account. The calculated drift-velocity for one-dimensional electron gas is found to be smaller than that for two-dimensional electron gas.
In order to clarify the phase relationship between UN and Me (Me:Ru, Rh, Pd), the starting materials containing UN and Me with the molar ratio of 1:3 were heated at temperatures from 873 K to 1673 K at nitrogen pressures from vacuum ( 10 -2 Pa) to 1 atm. Powder X-ray diffraction and SEM observation, EDX analysis were made for identification of the products. The reactions between UN and Ru and between UN and Rh produced URu 3 (Cu 3 Au type) and URh 3 (Cu 3 Au type) as intermetallic compounds, respectively. In the reaction between UN and Pd, UPd 4 phase (U:18 ∼ 20 at. %, Cu 3 Au type) was formed in addition to UPd 3 (TiNi 3 type).
