vibration signals was developed. The pattern recognition method was applied in this technique. The feature of the technique is that various kinds of obtained measurement values were spectrum conversion for every measurement value on multidimensional vector space that is expressed as a Mahalanobis Distance corresponding to a state. This technique was applied to diagnosis of rolling element bearing condition, and was verified by test fixture in the course of progressing degradation of rolling element bearing condition, from the normal state to abnormal state as running short of oil or seizure.

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This paper describes a modeling of a smart flexible beam composed four piezoelectric materials due to monitor and detect the fault of the system using health monitoring technique. For example, the damage of piezoelectric materials and the breaking wire. A model of the smart flexible beam with the fault is expressed by a linear parameter varying system. The output signal of the object system is affected by damage of piezoelectric materials and breaking wire. Subspace state space identification is adopted in order to detect the fault in this paper. Numerical and experimental results indicates that the fault detection can be achieved by using proposed method.

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Because the crack or damage at the foundation of structure deteriorates the reliability of the structure itself and sometimes breakes the structure, we are requested to develop the technique for non-distructive monitoring of structures. In this paper, we proposed the monitoring technique based on the parameter identification of the structure and its fundation. After the structure was imaginary separeted from the fundation, parameters of the structure was identified. Then the spring constant of the fundation was estimated. We applied our technique to the pole and got the good identification results.

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So far, many techniques for detecting cracks in structures using dynamical response have been proposed. Most of them assume that the cracks are open crack, which does not close during vibration. However many of actual cracks are breathing crack which opens and closes during vibration. In a previous report the authors proposed a technique for detecting breathing cracks in a beam. It detects the cracks assuming the cracks may exist on the upper surface or lower surface of the beam. In this report the proposed techniqe is extended to determine simultaneously the surface on which breathing cracks exist. Numerical simulation is conducted to show the applicability of the proposed technique.

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Strange sounds generated by machines are expressed by onomatopoeia. And onomatopoeia expresses trouble or poor condition of the machines. Especially, many kinds of onomatopoeia are used for expressing strange sound of automobiles, and the relationship between onomatopoeia and the sources of strange sound is reported. In this study application of onomatopoeia for expressing strange sound is discussed. Onomatopoeia is language which people utter. Therefore it is necessary to clarify the relationship between the frequencies perceived to sound like the onomatopoeic word and uttered sounds. In this report, we paid attention to both the vowel and the consonant of uttered sound of onomatopoeia. As a result we found that the utterance time of a consonant changes by the mechanism of utterance. And the ratio of energy between the vowel and the consonant influences frequency of the sound that an onomatopoeia expresses.

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This paper concerns the retraining of learning machines that are trained! to classify abnormal operating conditions of mechanical systems. Detection of the emergence of new data classes is mainly discussed that can trigger reconstruction of the training data set and retraining of the classifier to obtain updated discriminants. In our approach, two self-organizing maps (SOM), one with short term memory representing the current tendency and the other with long term memory representing the acquired knowledge, are used to detect the changes in the data structure by mapping the reference vectors in the long term SOM onto those in the short term SOM. A simple example using the data collected from draw-texturing machines is provided.

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In order to encourage the spread of distributed energy systems, an autonomous diagnosis is effective for the supporting technology. The purpose of this study is to develop the autonomous diagnosis algorithm using the fieldbus, which makes it possible to share much information of field devices. The authors constructed an experimental apparatus of a hot water supply process, which is one of the key component of distributed energy systems, and a measurement and control system with fieldbus devices. In this paper, the integration algorithm of the process diagnosis on the basis of the calculation of the overall heat transfer coefficient and the device monitoring using the statuses in the FOUNDATION fieldbus was developed and its effectiveness was confirmed experimentally.

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This paper focuses on a way to control direct current flow in a thick-walled structure. We locally heat a part of the surface of a thick-walled pipe for controlling the direct current flow, which will be led to the back wall of the pipe, and sensitively detect an artificial slit on the inner surface of the pipe by means of the direct current potential drop technique.

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In this study, we estimated the damage pattern in a CFRP cross-ply laminate containing an open hole using an embedded Fiber Bragg Gratings (FBG) sensor. The damage pattern near the hole was investigated by finite element an alysis with cohesive elements, and the reflection spectrum of the embedded FBG sensor was analyzed from the strain distribution obtained in the damage analysis. Based on the above analysis, the damage pattern expressed by the residual strength distribution of the cohesive elements was optimized as an inverse problem, while the spectrum shape was adopted as the objective function. The damage pattern estimated from the measured spectrum agreed with the observation.

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In order to analyze the crack closure of a fatigue crack, nonlinear ultrasound is applied. In introduction of fatigue crack we develop the crack opening monitoring procedures using TOFD method to obtain the reliable result about the relation between crack opening displacement and nonlinear ultrasound. Longitudinal ultrasonic wave of 6.4MHz in frequency with large amplitude incident to three point bending aluminum alloy specimen. Normal probe and angle probe are fabricated for nonlinear ultrasound measurement. As the results, in addition to secondary superharmonics of 12.8 MHz in frequency, especially in angle probe measurement, remarkable subharmonics of 3.2MHz in frequency was observed. Mechanism of subharmonics was also investigated.

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Cracking in longitudinal welded high-energy piping in fossil power plants has been a potential problem for over 20 years. Ultrasonic examination is one technique that helps detect cracking at stages early enough to implement corrective measures. Current ultrasonic methods range from traditional pulse echo techniques, which require a traditional raster scan, to recent Time of Flight Diffraction (TOFD) and phased array techniques. These cutting-edge methods continue to improve, both in terms of cost and the amount of quality information. This report discusses the development of an ultrasonic inspection system and the applicability of the TOFD and phase array techniques to the detection and sizing of cracking, and the concept of a defect characterization approach in heat affected zones in welded high-energy piping.

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Electromagnetic acoustic resonance (EMAR) is a contactless resonant method with an electromagnetic acoustic transducer (EMAT). This method is free from extra energy losses, resulting in the measurement of intrinsic ultrasonic attenuation in solids. In this study, the EMAR was applied to detect the creep damage of a nickel-based super-alloy, Waspaloy. The material was exposed to the temperature of 1073K at various stresses. We measured ultrasonic attenuation for 1-6-MHz frequency range as the creep advanced. The attenuation coefficient exhibits much larger sensitivity to the damage accumulation than the velocity. It shows a maximum around 35-40% of the whole life, which is interpreted as resulting from microstructural changes, especially, dislocation mobility and coarsening ofγ'-precipitates. This is supported by SEM and TEM observations for the dislocation structure and γ'-precipitates. This technique has a potential to assess thp damage advance and to predict the creep life of metals.

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In the thermoelastic stress analysis, stress distribution is measured by lock-in infrared thermography, which correlates temperature change due to the thermoelastic effect with reference loading signal. Loading signal from external source, such as load-cell, strain gage or displacement gage, is usually employed as a reference signal in the conventional technique. In this study, a self-reference lock-in thermography was newly developed, in which a reference signal was constructed by using the same sequential data on thermoelastic temperature change. Temperature change in a region of interest was correlated with that in a remote area for reference signal construction. The lock-in algorithm based on the least squares method was employed for signal processing under random loading. It enabled us to measure the distribution of relative intensity of applied stress under random loading without using any external loading signal. Proposed self-reference lock-in thermography was applied for crack identification based on the detection of significant thermoelastic temperature change due to the stress singularity in the vicinity of crack tips. It was found that significant temperature change was observed at the crack tip in the self-reference lock-in thermal image, demonstrating the feasibility of the proposed technique.

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A head of the golf wood club is hollow, and its thickness at the contact point to a ball is very small as like 2mm in order to get a high repulsive power. Although the lost wax method, which is one of manufacturing methods, is easy to mold it, there is fear of producing micro shrinkages. The micro shrinkages can give rise to early fracture in service, depending on their sizes and locations. In this study, in order to investigate whether the infrared thermograpy with pulsed heating can be applicable to detect their micro shrinkages near the surface, some test pieces with a small hole were prepared, and some experiments and nonsteady heat conduction analysis were carried out. The results show that it is easy to detect for the defects whose diameteris 1mm when the defects exist very near the surface as like 0.2mm.

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