Development of a real-time beam current monitoring system for microbeam scanning-PIXE analysis using a ceramic channel electron multiplier

Microbeam scanning-PIXE (micro-PIXE) analysis is a useful method for obtaining information of multi-elemental distribution in samples by two-dimensional images of sample surfaces such as mammalian cells, tissues, and other environmental monitoring species. In addition to elemental distribution information, quantitative analysis is in demand for further investigations of environmental and biomedical studies concerning heavy metals accumulated in terms of cells and sub-cellular organelles. To make quantitative analysis possible, a real-time beam monitoring system that gives a precise number of ions, and an output independent from a sample that enables one to keep a beam resolution of micrometer size is required. In this paper, we report on the development of beam current monitoring. The beam current was monitored using a ceramic channel electron multiplier (CEM) to detect secondary electrons induced from a 50 nm thick carbon film (10 μg/cm²). This carbon film was attached to a sample holder, which was set at the targeted sample position. The output value of the CEM was proportional to the Faraday cup installed just after the sample position. The beam resolution was measured using off-axis STIM by scanning a copper grid, and was estimated at 1.79 and 1.72 μm for the horizontal and vertical directions, respectively, sufficient for routine micro-PIXE analysis.     

Analysis of fuel pin behavior under slow-ramp type transient overpower condition by using the fuel performance evaluation code ‘FEMAXI-FBR’

FEMAXI-FBR has been developed as the one module of the core disruptive accident analysis code ‘ASTERIA-FBR’ in order to evaluate the mixed oxide (MOX) fuel performance under steady, transient and accident conditions of fast reactors consistently. On the basis of light water reactor (LWR) fuel performance evaluation code ‘FEMAXI-6’, FEMAXI-FBR develops specific models for the fast reactor fuel performance, such as restructuring, material migration during steady state and transient, melting cavity formation and pressure during accident, so that it can evaluate the fuel failure during accident. The analysis of test pin with slow transient over power test of CABRI-2 program was conducted from steady to transient. The test pin was pre-irradiated and tested under transient overpower with several % P ₀/s (P ₀: steady state power) of the power rate. Analysis results of the gas release ratio, pin failure time, and fuel melt radius were compared to measured values. The analysis results of the steady and transient performances were also compared with the measured values. The compared performances are gas release ratio, fuel restructuring for steady state and linear power and melt radius at failure during transient. This analysis result reproduces the measured value. It was concluded that FEMAXI-FBR is effective to evaluate fast reactor fuel performances from steady state to accident conditions.     

Effects of ultrasonic vibration on the wear characteristics of a carbon steel: Analysis of the wear mechanism

To explain the fact that the wear rate of a carbon steel subjected to ultrasonic vibration decreases with an increase in the amplitude of vibration, a simple equation for the wear rate was derived using the theories of adhesive wear and analytical results of vibration. Analytical predictions were in good agreement with experimental results. One of the main factors affecting the wear behaviour under vibration is the contact time between specimens during 1 cycle of vibration. The amount of oxygen adsorbed on rubbing surfaces with repeated dynamic contact loading also affects the wear rate. The activation energy of oxygen adsorption with vibration is considered to be lower than that found in the process of ordinary wear without vibration. The variation in hardness of worn surfaces due to repeated friction passes has little effect on the wear rate with vibration.     

Parallelization of genetic algorithm with sexual selection

We propose a parallel genetic algorithm with sexual selection. In genetic algorithms with sexual selection with one population, females keep their traits around local optima by using a lower mutation rate than that of the males, while the males change their traits actively. When a runaway process takes place, the transitions of the males' traits are biased toward a certain direction which depends on the bias of the females' preferences. If the population size is large, the search converges quickly. However, the large population size causes a decrease in search performance. In the proposed method with parallelization, the population size of each subpopulation is maintained adequately, and each subpopulation seeks its own direction of evolution independently. As a result, the proposed method makes a search converge quickly because the runaway process which leads to intermittent evolution tends to take place more quickly than one population model. We applied the proposed method to some test problems. In these problems, while the performance of conventional genetic algorithms was decreased by parallelization, the proposed method exhibited better performance with parallelization. Moreover, the performance of the proposed method is better than that of conventional methods. This capability of parallelization is a remarkable characteristic of sexual selection. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 42–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20029     

Manufacturing and material properties of ultralarge size forgings for advanced BWRPV

Ultralarge size forgings for the advanced boiling water reactor (ABWR) pressure vessel as represented by the bottom petal made from a 600 ton ingot have been developed. The bottom petal is a larger wall thickness ring with 10 integrated nozzles inside and outside the ring. The outer diameter is 7.8 m, the height is 1.8 m and the wall thickness if 1.1 m in the as-forged condition. A very high purity level of P 0.003% and S 0.003% can be obtained by the application of double-refining processes to all the molten steel. The forging shows a homogeneous chemical distribution, sound internal qualities and adequate impact properties.This paper summarizes the manufacturing technique and material properties of large size forgings such as the bottom petal, the shell with integrated skirt and the bottom dome.     

Long-term clinical outcome of extracorporeal shock wave lithotripsy monotherapy for staghorn calculi

The thickness (TBmt) and fiber pennation angle (TBpen) of triceps brachii as well as isokinetic force developed during elbow extension were measured in Olympic athletes to investigate the relationship between muscle fiber pennation and force generation capability. The subjects were male members of the 1996 Japanese Olympic team who competed in seven different events; 9 wrestlers, 16 soccer players, 11 sprinters, 5 judo athletes, 7 gymnasts, 9 rowers and 18 baseball players. The TBmt and TBpen, measured by a B-mode ultrasound, ranged between 29 mm and 50 mm and between 11 degrees and 30 degrees, respectively, and on average were larger in the judo athletes, wrestlers and gymnasts compared to the other groups. A significant correlation (r=0.580, p < 0.05) was found between TPpen and TBmt per unit of the upper arm length, and so the observed event-related differences in TBpen tended to reflect the differences in TBmt. The isokinetic forces relative to the cross-sectional area (CSA) estimated from TBmt, measured at two constant velocities of 1.05 rad/s (F1.05/CSA) and 3.14 rad/s (F3.14/ CSA), were negatively correlated to the CSA; r=-0.617 (p < 0.05) for F1.05/CSA and r=-0.635 (p < 0.05) for F3.14/CSA. In addition, low but significant negative correlations existed between TBpen and both F1.05/CSA (r=-0.365, p < 0.05) and F3.14/ CSA (r=-0.336, p <0.05). Even when the effect of TBpen was statistically normalized, the F1.05/CSA and F3.14/CSA were still negatively correlated to the CSA, r=-0.530 (p < 0.05) for F1.05/ CSA and r=-0.561 (p < 0.05) for F3.14/CSA. Therefore, at least in the Olympic athletes tested in this study, the magnitude of the pennation angles reflects muscle size, but it does not seem to be a factor that explains extensively the lower F/CSA in athletes with large muscle size.     

Formation of an Orientation Preference Map – Gradual Inhibition Method

Formation of an orientation preference map due to external visual stimuli in the primary visual area of the cerebral cortex is investigated in a two-layered neural network model, where a cluster learning rule is used together with ordinary Hebbian learning rule. We succeed in solving directly a set of simultaneous equations by numerical iterations using a gradual inhibition method. Previously, an alternative solution was found by applying a Self-Consistent Monte Carlo (SCMC) method. The gradual inhibition method in an iterative procedure can give a more precise solution efficiently with fewer computational tasks than the SCMC method.     

A method for selecting similar learning data in the prediction of time series using neural networks

This paper explores a method of improving the predictive performance by the multi-layer feedforward neural network in time series predicting. For the similar data selective learning method, we propose a method of weighting the distance by a power function of correlation coefficients for the time series (CSDS method). The results of numerical experiments show that with the case of a time series whose nature is rather choppy or chaotic, using the CSDS method appropriately is considerably effective to improve the predictive performance and its performance is considerably better than that by the previously proposed other methods.     

Predicting the Heating Temperature of Soymilk Products Using Fluorescence Fingerprints

A novel measurement technique using fluorescence fingerprints (FFs) was developed to measure the degree of heat treatment applied to soymilk. FFs are a set of fluorescence spectra acquired at consecutive excitation wavelengths. Soymilk was heated at 50, 60, 70, 80, or 90 °C, for 10 min, and the samples were measured both in the liquid and freeze-dried forms. Partial least squares (PLS) regression models were constructed to predict heating temperature from the FFs of liquid soymilk and freeze-dried soymilk. Heating temperatures were predicted from soymilk FFs with root-mean-square errors of prediction (RMSEP) and R ²P of 7.20 °C and 0.92 and from freeze-dried soymilk FFs with RMSEP and R ²P of 9.00 °C and 0.89, respectively. The fluorescence of aromatic amino acids and Maillard products mainly contributed to the prediction models. FF measurement proved to be effective for the objective control of the soymilk heating process.     

Electrical conductivity of Nd1−x Ca x Sc1−y Mg y O3 perovskite-type oxides

The electrical conductivities of Nd_1−x Ca _x Sc_1−y Mg _y O₃ were measured in the temperature range from 673 to 1273 K under both wet and dry conditions. The optimum Ca²⁺ doping concentration to the Nd³⁺ site in NdScO₃ was found to be the range from 5 to 10%. Hole conduction was predominant under dry and highly oxidized conditions of P(O₂) > 10⁻² kPa in the temperature range from 973 to 1273 K, and proton conduction was predominant under wet and reduced conditions in the temperature range from 673 to 973 K. Oxide ion conduction was predominant under wet and reduced conditions in the temperature range from 1073 to 1273 K. The Mg²⁺ doping concentration limit for the Sc³⁺ site to hold a single crystal phase was 2%, and this doping enhanced hole conduction.