A method and apparatus for locating a leak which produces a continuous acoustic emission having background noise and spikes, comprises continuously monitoring the acoustic emissions using spaced apart detectors which produce signals having background noise and spikes corresponding to those of the continuous acoustic emissions. The spikes of one signal are offset in time with respect to the spikes of the other signal, which corresponds to the difference in travel time of the acoustic signals to each of the detectors. By measuring the offset between the spikes, the relative position of the acoustic emission, and thus the relative position of the leak, can be determined with respect to the position of the detectors. To facilitate separating the spikes from the background noise, a floating detection threshold value is applied to the signals for eliminating the background noise.

Acoustic emission leak source location

A method of detecting a leakage of fluid is disclosed, in which a leaking sound, which is produced when the pipe is broken and propagates through the pipe, is detected by a couple of acoustic sensors (A, B) mounted to a pipe (C) through which fluid flows at portions separated from each other with a proper distance, the amplitudes of a plurality of different frequency components extracted from the output signals of the acoustic sensors are obtained and then a leaking location of fluid in the pipe and a leaking amount of fluid are determined on the basis of these amplitudes.

Method of detecting a leakage of fluid

An apparatus and method for determining the location of a pipe leak detects the pipe leak sound at a first remote location and at a second remote location, and generates first and second signals indicative of the sound. A time lay between the first and second signals is calculated at each of a plurality of frequencies. Integer multiplies of an associated period are added to each time lag to form a plurality of potential time delays at each of the plurality of frequencies. The plurality of potential time delays at all of the plurality of frequencies are stored in a memory. The time delay value which occurs most frequently is selected from the memory and is utilized to calculate the location of the sound source relative to the first and second locations. The invention can also be employed to determined the location of a sound source other than a pipe leak.

Method and apparatus for determining the location of a sound source

A leak detector is proposed for fluid systems serving intermittent loads. The device generates a signal representative of the minimum level of flow occurring from time to time, this level of flow being taken as the rate of leakage. On the basis of this signal, the device generates outputs indicative of the presence and relative magnitude of leakage. A preferred form of the device monitors flow with a thermal fluid flow detector which is adapted to be removably mounted on a distribution system pipe and to be sufficiently inexpensive to permit wide application of the device to small fluid distribution systems, such as residential water systems.

Leak detector for fluid distribution systems serving intermittent loads

PURPOSE: To control vehicle speed and steering by executing the instructions in a memory sequentially according to the signals fed from a sensor which detects the speed and direction of a vehicle. CONSTITUTION: Vehicle speed, vehicle running angle instruction, and the like based on the travel distance are written in a memory 1. A speed control system 2 compares the vehicle speed instruction from the memory 1 with the real vehicle speed fed from a pulse pick-up 3 fitted on an axle 7, determines the deviation, and controls a drive motor 4. A steering control system 5 compares the instruction from the memory 1 with the angle signal from a direction sensor 6 which detects the vehicle running angle, and conducts steering control so as to cause the vehicle running angle to accord with the instructed value. COPYRIGHT: (C)1979,JPO&Japio

Unmanned vehicle system

PURPOSE:To make it possible to change arbitrarily a monitor section without change of the arrangement interval of sensors, by delaying one of detection outputs of two sets of acoustic emission (AE) sensors by a prescribed time and by deciding the phase difference between this output and the other by comparison CONSTITUTION:The phase difference between the receiving detection output of AE sensor 11b and the receiving detection output of AE sensor 11a which is delayed in delay circuit 13 of phase deciding part 15 by prescribed time T1 is decided by deciding circuit 14, and circuit 14 generates a decision pulse only when the phase of the delayed detection output advances, and generation position P of the AE wave signal is detected by signal processing circuit 16 to monitor the AE wave signal Consequently, only when distance D1 from sensor 11a to detection point P is shorter than distance D1 from sensor 11b, the position of detection point P is detected, and the monitor region is limited to prevent the influence of noise and so on In this case, detection points different in distances D1 and D2 can be determined on the basis of expressions I and II by changing time T1, and the monitor section can be changed arbitrarily without change of the arrangement position of sensors Here, V is the AE wave propagation speed, and L is the delay equivalent distance

Ae monitor unit

PURPOSE:To make the detection of leakage positions from piping simple and inexpensive by disposing respectively different numbers of thermocouples in a plurality of measuring positions along the piping, connecting said thermocouples in series and providing an electromotive force measuring instrument between both terminals thereof. CONSTITUTION:Junction points of the strands 2a 2b of thermocouples are disposed, e.g., 1 at the A point, 2 at the B point, 4 at the C point and 8 at the D point, respectively in proximity to piping 1. The junction pints of the strands 2b 2a are disposed respectively in the ordinary temperature region at each point. If at this time any temperature change occurs at the A point, the change for one of thermoelectromotive force for one piece occurs between terminals 4a, 4b and if the temperature change of the same quantity occurs at the B point, a twice larger power change occurs at the B point. This becomes 4 times at the C point and 8 times at the D point. If the temperature changes when leakage occurs in the piping are beforehand empirically measured and the change in thermoelectromotive force per piece of the thermocouples by these is measured, the leakage position may be detected from the change in the electromotive force between 4a, 4b.

Leakage position detector

PURPOSE:To make it possible to discriminate an AE wave easily from an impulsive noise signal, by measuring the duration width of the signal received by an AE sensor and by deciding this signal as an AE wave signal only when the duration width above is longer than a prescribed time width CONSTITUTION:Many noise signals are received besides an AE wave signal by AE sensor 1, and signals are sent to duration width mesuring circuit 4, and pulse signals corresponding to respective duration width of noise signals and the AE wave signal are output from comparator 6 and are sent to deciding circuit 9 Mask circuit 10 does not output a pulse signal when the signal received by AE sensor 1 is the noise signal, but circuit 10 outputs the pulse signal when the received signal is an AE wave signal, and AE wave processing circuit 8 is operated by this pulse signal, and thus, erroneous detection of the AE wave generation position and so on dependent upon noise signals can be prevented

Ae wave discriminating unit

PURPOSE:To provide a method of guiding a driverless movable vehicle within a nuclear reactor for inspection, and in which the vehicle is guided without rail or guide tape through control of the angle of the direction of progress on the basis of a magnetic needle mounted on the vehicle and pointing in the direction of the terrestrial magnetism

Shinomiya Yasuo

Papers

Ae monitor unit

Leakage position detector

Ae wave discriminating unit

Method of guiding movable vehicle

Abnormality detecting device of inside of reactor container