Measuring and testing – Vibration – By mechanical waves
Patent
1997-04-01
1998-08-25
Williams, Hezron E.
Measuring and testing
Vibration
By mechanical waves
364554, 364550, 73 405A, 73660, G08B 2100, G06F 1546, G06F 1710, G05B 1302
Patent
active
057984590
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a subject identification method, a subject identification apparatus, and a subject identification system, which are adapted for performing an examination as to whether any change exists on an subject, such as whether or not the subject is the same one or the same type of one, whether the subject is placed under the same condition, or whether the subject is in the same state, or adapted for performing an estimation of a degree of the change on the subject.
BACKGROUND ART
Hitherto, there have been proposed in various fields various schemes for detecting a malfunction or a failure of devices, products, facilities and the like.
Hereinafter, there will be explained, by way of example, a scheme in which leakage of a gas, such as inflammable gas, toxic gas and the like, or a liquid, which are treated in manufacturing devices and facilities of a gas manufacturing plant, an oil manufacturing plant and a chemical plant, is detected on the basis of a leakage signal having an ultrasonic frequency band which may emanate when the above-mentioned gas or liquid is leaked through microapertures of instruments, laying pipes or the like, for example, eroded apertures due to the aged deterioration, and the malfunction of the facilities is detected in accordance with the presence or absence of the leakage.
Hitherto, in the above-mentioned equipments and plants, as a scheme of detecting leakage of inflammable gas and toxic gas, there is generally used a concentration type gas sensor established permanently. The concentration type gas sensor adopts a scheme in which the leaked gas is only detected when it reaches a certain detected concentration level or more. Accordingly, there is a need to install the concentration type gas sensor in a place where the gas is prone to stay. However, this scheme involves such drawbacks that it is difficult to select such a place, and a detection precision varies under the influence of the direction of the wind. Specifically, in a case where a leakage occurs far from a place where the gas sensor is installed, it happens that a large amount of gas is leaked owing to a diffusion in addition to the influence of the wind until the gas concentration reaches a detection level. In view of the foregoing, in order to earlier detect a leakage with the concentration type gas sensor, there is a need to provide a lot of concentration type gas sensors.
As another technology of leakage detection, an instrument (an ultrasonic leakage detector) for catching and detecting ultrasounds, which emanate when gas is ejected through microapertures, comes onto the market. As a scheme in which the above-mentioned technology is further developed so as to detect a leakage source, Japanese Utility Model Application Laid Open Gazette No. Sho.60-146834 discloses a technology in which a paraboloidal body is partitioned with segments so that ultrasonic sensors are accommodated into the associated partitions, respectively, and a position of the leakage source is detected in accordance with a turn-on condition of the monitor lamp of the display of the associated one of the respective sensors.
However, in any types of technology mentioned above, in which ultrasounds involved in the leakage are caught, it is possible to catch the ultrasounds when there is no ultrasonic noises other than leakage sounds. Thus, those types of technology are effective only in a place having environment, which is not subjected to the ultrasonic noises, such as pipe lines installed in an uncultivated field. On the contrary, there will exist a limitless number of ultrasonic noises on the plants and the manufacturing devices which need a leakage sensing technology. Those ultrasonic noises are as follows: leakage sounds of normal steam emanated from valve stems, such as a trip & throttle valve and a governing valve, which constitute a pump driving steam turbine in a manufacturing device; leakage sounds of normal steam emanated from a turbine rotor shaft seal packing of the turbine; leakage sounds of normal
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patent: 5623402 (1997-04-01), Johnson
Ohba Ryoji
Tamanoi Yoshihito
Japan as represented by President of Hokkaido University
Koa Oil Company Limited
Miller Rose M.
Williams Hezron E.
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