Selective transalkylation of naphthalene and ethylnaphthalene over solid acid catalysts

A high 2,6-diethylnaphthalene (2,6-DEN) isomer ratio (62%) and a good 2,6-DEN yield (46 mol%) were obtained by the transethylation of 2-ethylnaphthalene with tetraethylbenzenes over H-Y zeolite catalyst. Steric hindrance and electron density at the substitution sites of naphthalene are two influential factors for excellent selectivity. Silica-alumina catalyst, which cannot be expected to possess shape selectivity, also demonstrated a high 2,6-DEN selectivity.     

Theory and experiment on thermal shock fracture of initially corner-cracked nozzle

The phenomenon of the pressurized thermal shock on the reactor pressure vessel is expected to occur in the case of such an accident as the small loss of the coolant accident in the PWR nuclear plant. In order to study the structural integrity of the reactor pressure vessel under the pressurized thermal shock, the cleavage thermal shock fracture experiment was conducted here using an initially corner-cracked nozzle type specimen made of the pressure vessel steel A508 class 3. The fracture mechanics analysis was performed to asses bthe crack behaviors in the experiment using the time dependent stress intensity factor deduced from the three-dimensional J integral with the thermal effect.     

Elastic-plastic analysis on stable crack growth for center cracked plate: a benchmark study

For the evaluation of the accuracy of the finite element method in the elastic-plastic stable crack growth analysis, a benchmark test using a center cracked specimen of Type 304 stainless steel is performed. Six groups in the Japan Society of Mechanical Engineers participate in this project and provide six numerical solutions for the given problem using different solution methods and computer codes assuming the plane stress condition. The criterion for the crack extension used here is the experimental relationship between the gauge displacement and the crack extension amount at the specimen surface. The results of the numerical analyses and the experiment are compared with each other with regard to the global deformation behavior and the J-integral value before the crack initiation as well as during the crack extension. Discussion is made about the sources of scattering between the numerical solutions and the experiment.     

Quantitative nondestructive evaluation with ultrasonic method using neural networks and computational mechanics

This paper describes an inverse analysis method using hierarchical neural networks and computational mechanics, and its application to the quantitative nondestructive evaluation with the ultrasonic method. The present method consists of three subprocesses. First, by parametrically changing the location and size of a defect hidden in solid, elastic wave propagation in the solid is calculated with the dynamic finite element method. Second, the back-propagation neural network is trained using the calculated relationships between the defect parameters and the dynamic responses of solid surface. Finally, the trained network is utilized to determine appropriate defect parameters from some measured dynamic responses of solid surface. The accuracy and efficiency of the present method are discussed in detail through the identification of size and location of a defect hidden in solid.This work is financially supported by the Grant-in-Aid for the scientific research of the Ministry of Education, Japan.     

Fracture behavior of cracked Type 304 stainless steel pipes under tensile and thermal loadings

Because of frequent discoveries of stress corrosion cracking in BWR primary piping systems, it became an urgent problem to evaluate the possibility of unstable fracture of flawed stainless steel pipes. To understand the fundamental fracture property as well as the behavior under actual plant conditions, the authors performed the following four types of tests on the cracked Type 304 stainless steel plates or pipes.

1. 1. Plate fracture test under tensile loading.

2. 2. Pipe fracture test under tensile loading.

3. 3. Leak-before-break test under high-compliance loading.

4. 4. Thermal shock test.

These test revealed quite high resistance of the flawed stainless steel pipes against unstable fracture.     

Noncontact pulse wave detection by two-band infrared video-based measurement on face without visible lighting

In this paper, we propose a novel noncontact pulse wave monitoring method that is robust to fluctuations in illumination through use of two-band infrared video signals. Because the proposed method uses infrared light for illumination, the method can be used to detect a pulse wave on a human face without visible lighting. The corresponding two-band pixel values in the video signals can be separated into hemoglobin and shading components by application of a separation matrix in logarithmic space for the two pixel values. Because the shading component has been separated, the extracted hemoglobin component is then robust to fluctuations in the illumination. The pixel values in the region of interest were spatially averaged over all the pixels of each frame. These averaged values were then used to form the raw trace signal. Finally, the pulse wave and the corresponding pulse rate were obtained from the raw trace signal through several signal processing stages, including detrending, use of an adaptive bandpass filter, and peak detection. We evaluated the absolute error rate for the pulse rate between the estimated value and the ground truth obtained using an electrocardiogram. In the experiments, we found that the performance of the proposed method was greatly improved compared with that of conventional methods using single-band infrared video.     

Evaluation of induction heating stress improvement (IHSI) treatment applied to nuclear primary piping

A new technique, IHSI (induction heating stress improvement), has been developed to reduce the tensile welding residual stress in the surface of steel piping for nuclear power plants, so reducing the susceptibility to stress corrosion. It is shown in this paper that the technique is effective and safe even if it is applied to piping which contains a small initial crack which is impossible to detect by ultrasonic inspection.     

A meshless method with conforming and nonconforming sub‐domains

An accurate and easy integration technique is desired for the meshless methods of weak form. As is well known, a sub‐domain method is often used in computational mechanics. The conforming sub‐domains, where the sub‐domains are not separated nor overlapped each other, are often used, while the nonconforming sub‐domains could be employed if needed. In the latter cases, the integrations of the sub‐domains may be performed easily by choosing a simple configuration. And then, the meshless method with nonconforming sub‐domains is considered one of the reasonable choices for computational mechanics without the troublesome integration. In this paper, we propose a new sub‐domain meshless method. It is noted that, because the method can employ both the conforming and the nonconforming sub‐domains, the integration for the weak form is necessarily accurate and easy by selecting the nonconforming sub‐domains with simple configuration. The boundary value problems including the Poisson's equation and the Helmholtz's equation are analyzed by using the proposed method. The numerical solutions are compared with the exact solutions and the solutions of the collocation method, showing that the relative errors by using the proposed method are smaller than those by using the collocation method and that the proposed method possesses a good convergence. Copyright © 2016 John Wiley & Sons, Ltd.