Ikata NPS (Nuclear Power Station) is tackling various problems, maintenance optimization, technical capability upgrading, encouraging talent, transferring technical knowledge, etc. with the aims of pursuing world-class technical capability and competitiveness. Referring to nuclear power plants in USA which have achieved high performance Ikata NPS changed the maintenance process and implemented condition based maintenance such as monitoring of vibration, lubricant and so on. So Ikata NPS could not only reduce the maintenance work volume but also improve the plant reliability by preventing any trouble proactively.

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In Japan, many of infra structures have been constructed after the World War II and the ages of them are more than 50 years. Many of bridge structures are also involved in the same situation. Considering current and future economical condition in Japan, Life Cycle Management is a very important key technology for bridge structures in order to keep the appropriate service level during the service life for users and tax payers under the limit budget of national and local government for maintenance. In this article, current states of life cycle management of bridge structures are introduced focusing on inspection and performance evaluation technologies of bridge members and systems.

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Authors have proposed a cantilever type of vibration energy harvester with piezocomposite for vibration condition monitoring applications of rotating machinery. Proposed energy harvester consisted of Macro-Fiber Composite (MFC) actuators in bimorph configuration. The dynamics of the vibration energy harvester can be modeled as a single degree-of-freedom, spring-mass-damper system with base excitation due to unbalance response of rotating machinery. Considering the electric circuit connected to the MFC, the equivalent two degree-of-freedom model is obtained. In this study, the energy balance equation is derived. The efficiency of vibration energy transfer to the electrical resistive load of the circuit is estimated by using the derived energy balance equation. The estimated generated maximum AC power is 105.3(μW) with the electrical resistive load 112.8(kΩ) at the resonant frequency of 26.25(Hz) under the excitation amplitude level 0.71(mm/s rms). It indicates that the impedance matching between MFC actuators and the electrical resistive load is effective for maximizing the AC power transfer of the vibration energy harvester. At this condition, input vibration power is calculated as 727(μW) from the energy balance equation, and then the efficiency of vibration energy transfer to the load is estimated as 17%.

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Many rotors are supported by an oil film bearing which has high stiffness. Since the gap of an oil film bearing is very small, we must suppress vibration as much as possible to prevent metal contact by an oil membrane break. Therefore the damping ratio is an important index to use when evaluating the rotor system stability. However it is difficult to identify the damping ratio under various conditions. In this paper, the damping ratio of oil film bearing rotor system is evaluated by using the tracking solver. This solver provides a continuous solution of damping ratio during rotation. We calculate the damping ratio of the oil film bearing with a dynamic vibration absorber which is developed for suppression of oil whip instability.

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In order to effectively identify faults of a rotating mechanics, a new kind of symptom parameter ------ Relative Ratio Symptom Parameter (RRSP) is proposed in this paper. Moreover, combined with Bayesian Network, the corresponding fault diagnosis system is built. In the paper, the vibration signals are monitored and measured and the relative ratio symptom parameter is calculated, of which the parameters whose identification index is bigger are chosen as the input of Bayesian Network, by observing and analyzing the output that is the probability of normal state and abnormal states, Bayesian Network in the mechanical fault diagnosis is proved to be effective by real data measured in each state of a rotating machine.

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The fault diagnosis by acoustic signals on reciprocal engine is more difficult than independent mechanical elements, because almost reciprocal engine is composed of great number of structural bodies and mechanical elements. Reciprocal engine find it hard to identify of fault elements to exist a number of noise sources within the engine. This paper experimentally examines the possibility of diagnose fault conditions about a four stroke outboard marine engine based on generated acoustic signals measured by two microphones. Artificially assumed fault condition in the outboard engine is concerning intake and exhaust valve spring. Identification of above the fault conditions has been carried out based on cross correlation function of close two points signals and paralleled ARX model (Auto Regressive with Extra Input) at diagnosed location within the engine. It is possible to diagnose above fault condition by the proposal SN ratio improvement method.

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Lubricating oil and hydraulic fluid deteriorate for the oxidation and contaminations from outside. The oil oxidation products repeat polycondensation and form oil-sludge including contaminations. But, the general oil analysis cannot analyze the situation of oil-sludge generation definitely. In this study, it was clarified that the judging oil-sludge generation was possible by using the separation oil-sludge from base oil by centrifugation and the comparison of laser transmittance before and after centrifugation.

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Degradation of oils is roughly classified into two types, one is caused by solid particles and the other is caused by oil oxidation products. Diagnosis methods for solid particles in oils have many standards and researches. However, there are few diagnosis methods for the oil oxidation products. In the present study, two themes were examined. At first, the filtration mechanism by a membrane filter was discussed using oxidized oils which were prepared in laboratory. Secondly, the transmittance of lights through the membrane patch was discussed using oxidized oils. As a result, we found that the color properties of reverse side of the membrane patch was different by the amount of the oil oxidation products, and we also found that the transmittance of lights through the membrane patch can distinguished the difference of a light color by deterioration level of the oil. They seem that these two new methods can evaluate the deterioration level of used oils. Furthermore, we developed new equipment for diagnosis of membrane patch color based on these results.

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In the steel plant, many equipments, machine elements and structures operate under a severe condition. Condition monitoring and diagnostic technology supported steel plant maintenance for many years. This report explains about the current state of steel plant maintenance and application of condition monitoring technology: particularly condition monitoring system, lubrication diagnosis and structural health monitoring.

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Evaluation of a lubrication condition of ball bearing becomes an important issue for safe operation of a machine. In this paper, an application of ultrasonic technique is attempted for a purpose of evaluating the lubrication conditions. Quantitative measurement of a dent size which forms the origin of flaking is important for an evaluation of lubrication conditions. The width of indentation having 0.45mm on a raceway surface of an inner ring becomes possible with the observation of the change in echo height reflected from a boundary surface between housing and outer ring of the ball bearing. Furthermore, it can be possible to evaluate an insufficiency of oil in ball bearing by the observation of reflection echo height variation from a contact surface of outer ring and ball. When a sufficiently oil is supplied to the inlet of contact surface between them, the echo height increases locally. However, degree of its increase becomes lower when oil supply is insufficient, and does not appear at all with running out of oil. A time lag between the bottom of valley in echo height variation and the sound axis of ultrasonic probe decreases gradually as supply of oil becomes insufficient, and it becomes zero by running out of oil at a contact surface.

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This study investigates an evaluation method to analyze the rolling behavior in ball bearings by an ultrasonic technique. The analysis uses the time interval T_I, which is defined as the duration between the two adjacent minimum peaks of the ultrasonic wave pulse echo intensity, as an evaluation basis. Since T_I corresponds with the duration between one passing and the next passing of individual balls through the highest loading area in the bearing, its value can present the actual rolling behavior of the balls. This study proposes a reasonable manner to extract each value, rather than averaged one, of T_I and compares the values of T_I obtained by the proposed manner with the results provided by Fourier analysis of the changes in ultrasonic wave pulse echo intensity with time.

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From the viewpoint of monitoring and maintenance (especially condition-based maintenance) of machinery, it is extremely important to recognize and quantify friction and wear phenomena, such as the progress of wear and the state of friction at interfaces. An acoustic emission (AE) is intimately related to the deformation and fracture of materials and the AE-based method is useful in obtaining large quantities of information relating to friction and wear phenomena. Accordingly, the AE method, unlike other estimation methods in current use, permits direct estimations and is very effective for the in-process monitoring of the state of rubbing surfaces. For the recognition and quantification of friction and wear phenomena, it is necessary to elucidate the relationship between AE signals and friction and wear phenomena. However, little is known regarding the relationship between AE and friction and wear phenomena, because of the complexity of such phenomena. To mitigate the complexity, not only experiments by repeated rubbing (a typical experimental method), but also experiments with the simplified friction systems have been performed in this study. As a result, the features of the AE parameters and the AE frequencies were revealed for the quantitative evaluation of wear state.

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In order to assess the sliding-rolling contact fatigue lives of surface-hardened sintered rollers from the view point of linear fracture mechanics, the crack propagation behavior has been investigated under a sliding-rolling contact condition. The surface-hardened rollers which have three kinds of artificial defects were fatigue tested, and the crack propagation rate was measured. The crack propagated from the hole was almost parallel to the roller surface. Therefore, the crack propagation under a sliding-rolling contact condition was supposed to be in the mode II. The parameters m and C in Paris's law were obtained from this experiment. Using these parameters, the fatigue lives of the surface hardened sintered roller were estimated. The estimated fatigue lives were almost the same as the experimental ones. The fatigue lives of the sintered rollers depend mainly on the pore distribution and the hardness. The relationship between the parameters in Paris's law and the hardness obtained in this paper might help to assess the sliding-rolling contact fatigue life.

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Today, it is normal for a bearing operating under good lubrication conditions to achieve an actual life of more than 10 times the life calculated using Lundberg-Palmgren's theory (L-P theory). Conversely, in the case of the lubricant with debris, the life of the bearing is actually less than the life calculated using L-P theory. These phenomena are considerable issue for the life design of bearings used in various machines. To solve this problem, the following life equation was developed. L_<able> = a_1 a_<NSK> L_<10> where a_1 is life modification factor for reliability, a_<NSK> is life modification factor for fatigue limit and lubrication condition, L_<10> is basic rating life based on the L-P theory. This new bearing life equation shows good agreement with actual life results.

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In order to evaluate and maintain the wire rope life, we introduce and propose two systems. First is SEMSOR (Sales & Excellent Maintenance System Of Ropes ) that contains wire rope tester, position measurement tool, control unit and Internet transmission system. Second is REXS (Rope EXchange Support system) that can calculate the rope life from the load data etc. Two systems have been applied to many site of crane and expected to refrain from occurring accident concerning for wire ropes on the crane.

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The cranes have been developing and progressing as the carrier machinery. In order to operate the cranes safety, they are designated the specific machinery by the occupational safety and health law and obligated the permission of production & issue of inspection, various inspection taking out the cranes license regular maintenance management to operate the crane On the other hand the cranes have been used for a long time after production currently a lot of cranes designed & produced by old standard & rule have been existed. So it is necessity to manage the cranes maintenance after understanding the designs requirement. I would like to introduce some example for cranes maintenance management or the history of cranes standard & rule.

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This paper describes the experimental study of nappe oscillation at a weir. We present characteristic of low frequency noise and how to suppress low frequency noise by nappe oscillation. Its sound can be suppressed by setting equipment at the lower end of a falling water sheet. Experimental results show the effectiveness of the equipment on suppression of low frequency noise.

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The inspection for CUI (Corrosion Under Insulation) of Oil-Plant and Pettrochemical-Plant spend high cost and heavy effort, Because of it's need sub-constraction. We have developed "Neutron Moisture Meter" using 252Cf neutron source for moisture under heat insulation of pipe and tower. The experimental results using prototype have demonstrated that prototype detect moisture under insulation, well. As soon as we will start using a general purpose "Low Noise Neutron Moisture Meter" on site.

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The purpose of this study is making 3D maps for obstacles recognition of guide dog robots. It is necessary that the robots recognize surrounding obstacles for working on the real environment. In order to recognize surrounding obstacles, the robots should have 3D maps of concerning the anticipated route where the robots will pass. We used a laser range sensor (LSR) for making 3D maps. The LSR is made rotated by a servo motor, so 3D data is measured by this rotating LSR. It was identified whether it is space that can be passed with the remodeled LSR for each individual space, and kept the aggregation as 3D grid data. By this way, we could make a 3D grid map of real environment such as the garden in university. And we have confirmed to be able to recognize the height information, for example the height of a stone wall and branches over the head.

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This study have aimed at building a remote health monitoring system by using the smart washer that be capable of self-exciting and self-measuring. This method is expected the automation of the inspection for the bolted joint, because periodic and high frequency evaluation and diagnosis can be realized from a remote server if a smart washer installed previously in the bolted joint. This paper describes the introduction of the WEB based remote health monitoring system and the method of the bolt loosening evaluation with supervisor.

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To avoid failures of an air-conditioner, we need suitable condition monitoring technique. Unfortunately, an air-conditioner has many parameters in it, i.e., inlet temperature, outlet temperature of a condenser or an evaporator, pressure at each component and input power to compressor and so on. Furthermore, we need expensive sensors to measure pressure. It is very difficult to monitor so many parameters from viewpoint of cost, setup in an air-conditioner and calculation cost of diagnosis technique. This is one of reasons why we must select suitable parameters for diagnosis. In this paper, we checked suitable parameters to monitor the condition of an air-conditioner by experiment. And then we applied neural network, i.e., NN, and support vector machine, i.e., SVM, with two types of kernel function to diagnose its failure. We also checked the effect of parameters on diagnosis performance to reduce the number of input parameter for NN or SVM. Finally, we selected several parameters for input data and showed good diagnosis ability of SVM with polynomial kernel.

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This study concerns a electromagnetic vibration energy harvester with a nonlinear oscillator. A vibrational energy harvester is an energy-harvesting device that is designed to collect extra energy from vibrating equipments, which is ordinarily discarded as heat. A conventional energy harvester is equipped with a linear oscillator, and designed so as to get large power by matching the natural frequency of the oscillator to the frequency of the input vibration to make a resonance. The problem is, however, that, if the input frequency changes even in a slight amount, the performance can become extremely worse because of the high-Q design. In this study, a vibration energy harvester using a nonlinear oscillator is proposed, which is designed to generate larger electric power for larger frequency range. This harvester consists of a nonlinear oscillator with hardening spring, a convertor, and a self-excitation circuit with a variable resistance of which value is controlled from negative to positive as a function of the amplitude of the response. This controlled resistance enables the oscillator to be entrained by the excitation in a large amplitude solution. In this paper, the impedance matching condition of the load resistance is particularly focused on to improve the regenerated power when entrained in a large amplitude solution. It is suggested that the impedance matching condition of the nonlinear energy harvester may be much different from that of the linear one, and the lower impedance may provide the higher regenerated power.

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Recently, the safety of food is valued. The consumer demands to specify in what situation farm products have been grown, and is doing various approachs that the producer, the distributor, and the distributor respond to it. In addition, a cheap environmental monitor system is hoped for for the spread in the future because it is tried to measure and to use weather information and information in the state of the soil for the labour for farming by research laboratories etc.The environmental monitor system for agriculture was developed based on such a demand, and it set it up in Mie Prefecture. This system acquires the image, the temperature, humidity, the quantity of solar radiation, latitude, the longitude, and the high degree, collects with the server in the remote place, and is open to the public on the web. Agricultural Cloud will be expected to be constructed by centering on such a system in the future.

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