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Automatically detecting a learner's stalled situation or deadlock in an educational support system using computers is very useful. This paper proposes a method for detecting such a deadlock on the basis of the record of a learner's operations and evaluates it by tests on human subjects. Specifically, it uses the moving variance of the operational time intervals to detect a deadlock. As a result, in about 80% of the practice problems with self-declarations of a deadlock by the subjects, the deadlock could be detected at a point in time prior to the self-declarations. In addition, deadlocks were detected by the proposed method in three cases in which states close to a deadlock had been determined from questions after the completion of the practice problems, even though there were no self-declarations. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(7): 63–75, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10256 [ABSTRACT FROM AUTHOR]

We studied the factors which determine the difficulty of practice problems in a computer language textbook. These problems have special features, which are that the amount of knowledge required to solve a problem is large and there is more than one way to find the solution. Moreover, if we give the textbook to learners in order to evaluate the difficulty of the practice problems, we have to take account of the fact that the learner may have trouble understanding and absorbing the explanatory part of the textbook. This, in turn, means that our analysis would need a very complex model. We overcame this by setting certain experimental conditions and so were able to limit our analysis to such factors as the deduction required to solve the problems. Furthermore, we undertook an analysis of factors which can be measured formally. To put this concretely, we studied the relationship between these formal factors and the error rate by means of an experiment using an actual beginner-level C language textbook. The results revealed that the number of inferences provided the best quantitative representation of the difficulty. In addition, we extracted special cognitive loading factors by conducting an error analysis of specific problems which included some deviation from the formal factors. We then made our model more accurate by including these factors among those which were found to be significant. In this way, we estimated the difficulty of the practice problems quantitatively, and showed the effectiveness of our proposed method. © 2000 Scripta Technica, Syst Comp Jpn, 31(4): 87–97, 2000 [ABSTRACT FROM AUTHOR]

A flame-resistant optical fiber with a stainless steel sheath is proposed. As a result of the flame test (IEEE 383 Standard) on a 12-fiber optical fiber cable based on the proposal, it was found that only the corrosion-protective paint on the stainless steel surface, which was exposed to the flame, was burned (burn length 30 to 45 cm). During this IEEE 383 Standard Flame Test, the fiber did not show any increase of optical loss. However, the optical lose began to increase within a certain period of time after the flame test, and the period is longer when the softening temperature of the secondary coating material is lower. The stainless steel surface should be coated with corrosion-resistance paint. As a result of the corrosion test, the chromate treatment is suitable for surface treatment. Vinyliden fluoride paint, dicarbolic acid paint with glycidyl acrylic or oil-free melamine polyester paint are effective for corrosion protection. [ABSTRACT FROM AUTHOR]

Aerial cable lines running in forests are often damaged by animals. This paper introduces an animal-resistant cable design by analyses of the fracture of metals when a shearing force is applied. As a result of the analyses, it is understood that when shearing forces are applied repeatedly to a metal plate without strain relaxation (similar to the case in which animals attack the cables), the metal does not fracture as long as the shearing energy is below a critical energy. This critical energy can be estimated from tensile strain at the yield point and the tensile stress at the fracture point. Therefore, it is possible to realize an animal-resistant metal sheath by making the critical energy higher than the shearing energy which an animal can apply on one impact. It wa found that the animal-resistant cable designed and fabricated by this method could withstand animal attacks. [ABSTRACT FROM AUTHOR]