Quantitative characterization of microcracking in A533B steel by acoustic emission

The initiation of microcracks at MsS inclusions and their coalescence during fracture toughness tests of ASTM A533B steel compact tension specimens were detected by an acoustic emission technique. The sources of emission, which are characterized by the crack size and orientation, fracture mode, and time history, are represented by a time-dependent moment tensor. Since the recorded waveforms are related to the moment tensor, the Green’s displacement functions of the specimen, and the transfer function of the recording system by a convolution integral in the theory of elastodynamics, the moment tensors are determined by techniques of deconvolution. Two types of sources were found: a tensile mode of crack caused by decohesion of MnS inclusion and the coalescence of microcracks with mixed tensile and shear modes. The dimensions and time durations of microcracks were also estimated in this study. T{upakanori} O{uphira}, Late Associate Professor of the Department of Metallurgy and Materials Science, University of Tokyo, Tokyo, Japan, died on December 9, 1987, at the age of 33 years. He had been a Visiting Scientist at Cornell University from 1984 through 1986 under the sponsorship of the Japan Society for the promotion of Science.     

Spontaneous behavior for cooperation through interaction: An emotionally intelligent robot system

This paper deals withspontaneous behavior for cooperation through interaction in a distributed autonomous robot system. Though a human gives the robots evaluation functions for the relation of cooperation among robots, each robot decides its behavior depending on its environment, its experience, and the behavior of other robots. The robot acquires a model of the behavior of the other robots through learning. Inspired by biological systems, the robot's behaviors are interpreted as emotional by an observer of the system. In psychology, the emotions have been considered to play important roles for generation of motivation and behavior selection. In this paper, the robot's behaviors are interpreted as follows: each robot feels frustration when its behavior decision does not fit its environment. Then, it changes its behavior to change its situation actively and spontaneously. The results show potential of intelligent behavior by emotions. This work was presented, in part, at the International Symposium on Artificial Life and Robotics, Oita, Japan, February 18–20, 1996     

Optimal design method with biomechanical analysis for a work environment reducing physical workload: illustration by application to work table height design

A work environment should be designed to minimise physical workload. We propose an optimal work environment design method to accomplish this, in which joint moment ratios were calculated by biomechanical analyses through digital human modelling (DHM) and were used to indicate physical workload. The work environment design problem was formulated as a multi-objective optimisation problem, minimising the average and maximum joint moment ratio values to determine the optimal work environment. Sequential approximate optimisation, which improves the accuracy of the response surface by sequentially adding new sampling points from a simulation, was applied to efficiently obtain a precise optimal solution. The proposed method was applied to designing a work table height for light assembly tasks. This method determined the optimal work table height considering the anthropometric diversity of workers from a relatively small number of subjects. Through this case study, the validity of the proposed method is discussed.     

Synthesis and Application of Stable Copper Oxide Nanoparticle Suspensions for Nanoparticulate Film Fabrication

Colloidal suspensions of copper oxide (CuO) nanoparticles were prepared by an alcothermal method, in which copper acetate was reacted with sodium hydroxide in the presence of acetic acid in ethanol at 78°C. The prepared suspension was stable for up to 1 month without stabilizers such as surfactants. Transmission electron microscopy analyses revealed that the suspension contained nanosized CuO particles of 5–10 nm size with a narrow size distribution. Nanoparticulate CuO films packed with grains smaller than 60 nm were fabricated on Si substrates by spin coating a suspension of CuO nanoparticles and subsequent heat treatment at 500°C.     

Tissue characterization of coronary plaque by kNN classifier with fractal-based features of IVUS RF-signal

We propose a tissue characterization method for coronary plaques by using fractal analysis-based features. Those features are obtained from radiofrequency (RF) signals measured by the intravascular ultrasound (IVUS) method. The IVUS method is used for the diagnosis of the acute coronary syndrome. In the proposed method, the fact that the complexity of the tissue structures is reflected in the RF signals is used. The effectiveness of the proposed method is verified through some experiments by using IVUS RF signals obtained from rabbits and human patients.     

Point mutation of alanine (31) to valine prohibits the folding of reduced lysozyme by sulfhydryl--disulfide interchange

In the preceding paper in this issue, we described the overproduction of one mutant chicken lysozyme in Escherichia coil.Since this lysozyme contained two amino acid substitutions (Ala³¹ValandAsn¹⁰⁶Ser)in addition to an extra methionine residue at theNH₂-terminus the substituted amino acid residues were convertedback to the original ones by means of oligonucleotide-directedsite-specific mutagenesis and in vitro recombination. Thus fourkinds of chicken lysozyme [Met^–1 Val³¹Ser¹⁰⁶-, Met^–1Ser¹⁰⁶-,Met^–1 Val³¹-and Met^–1 (wild type)] wereexpressed in E. coli. From the results of folding experimentsof the reduced lysozymes by sulfhydryl-disulfide interchangeat pH 8.0 and 38°C, follow ed by the specific activity measurementsof the folded en zymes, the following conclusions can be drawn:(i) an extra methionine residue at the NH₂-terminus reducesthe folding rate but does not affect the lysozyme activity ofthe folded enzyme; (ii) the substitution of Asn¹⁰⁶ by Ser decreasesthe activity to 58% of that of intact native lysozyme withoutchanging the folding rate; and (iii) the substitution of Ala³¹Val prohibits the correct folding of lysozyme. Since the wildtype enzyme (Met^–1-lysozyme) was activated in vitro withoutloss of specific activity, the systems described in this study(mutagenesis, overproduction, purification and folding of inactivemutant lysozymes) may be useful in the study of folding pathways,expression of biological activity and stability of lysozyme.     

How Does the Agents' Appearance Affect Users' Interpretation of the Agents' Attitudes: Experimental Investigation on Expressing the Same Artificial Sounds From Agents With Different Appearances

An experimental investigation into how the appearance of an agent such as a robot or PC affects people's interpretations of the agent's attitudes is presented. In general, people are said to create stereotypical agent behavioral models in their minds based on the agents' appearances, and these appearances significantly affect their way of interaction. Therefore, it is quite important to address with the following research question: How does an agent's appearance affect its interactions with people? Specifically, a preliminary experiment was conducted to select eight artificial sounds for which people can estimate two specific primitive attitudes (e.g., positive or negative). Then an experiment was conducted where the participants were presented with the selected artificial sounds through three kinds of agents: a MindStorms robot, AIBO robot, and laptop PC. In particular, the participants were asked to select the correct attitudes based on the sounds expressed by these three agents. The results showed that the participants had better interpretation rates when a PC presented the sounds and lower rates when the MindStorms and AIBO robots presented the sounds, even though the sounds expressed by these agents were the same. The results of this study contribute to the design policy of the interactive agents, such as, What types of appearances should agents have to effectively interact with people, and which kinds of information should these agents express to people?     

Effects of large-scale research funding programs: a Japanese case study

This study investigates the effects of large-scale research funding from the Japanese government on the research outcomes of university researchers. To evaluate the effects, we use the difference-in-differences estimator and measure research outcomes in terms of number of papers and citation counts per paper. Our analysis shows that the funding program led to an increase in the number of papers in some fields and an increase in the citation counts in the other fields. A comparison of our estimation results with assessment data obtained from peer reviews showed important differences. Since the characteristics of research vary according to the field, bibliometrics analysis should be used along with the peer review method for a more accurate analysis of research impact.