Abstract: The present invention relates to a method of determining a lubrication parameter indicative of a lubrication condition of an oil-lubricated rolling element bearing. The method comprises measuring high-frequency structure-borne acoustic emissions generated by asperity contact between rolling contact surfaces of the bearing, to provide a measured signal. The emitted acoustic energy is then extracted from the measured signal and the lubrication parameter is determined from the acoustic energy. The determination is made on the basis of a power-law relation between acoustic energy and the lubrication parameter.

Abstract: A system for sensing and communicating in a pipeline that contains a fluid. An acoustic signal containing information about a property of the fluid is produced in the pipeline. The signal is transmitted through the pipeline. The signal is received with the information and used by a control.

Abstract: An acoustic emissions testing device includes a testing sample, an acoustic sensor communicably coupled to the testing sample, and a load that is exerted on the sample. The sensor detects one or more acoustic events occurring within the sample. The acoustic transmits data to a data recorder, which includes a processor and storage medium for executing instructions provided by a software residing within the storage medium. Upon executing the instructions on the transmitted data, the toughness of the sample is objectively determined and can be ranked comparatively to the toughness of other samples. The instructions provide for categorizing the data into possible acoustic event points and background data points, interpolating a background noise curve, determining the actual acoustic event points, and calculating the area under each actual acoustic event point. In some embodiments, a graphical representation of the cumulative area for each actual acoustic event point is plotted against the corresponding load.

Abstract: An acoustic emissions testing device includes a testing sample including a hard surface, an acoustic sensor, an indenter coupled to the hard surface, and a load. The load is exerted on the indenter, which transfers the load to the hard surface. The acoustic sensor is communicably coupled to the testing sample and detects one or more acoustic events occurring within the testing sample. An acoustic emissions testing system includes a data recorder coupled to the testing device. The data recorder records the data from testing device. Based upon the data received, the toughness of the sample is objectively determined and can be ranked comparatively to the toughness of other samples. The load is ramped up to a peak load, held for a period of time, and then ramped down.

Abstract: A method, system and apparatus for testing properties of a hard component. The apparatus includes a holder, a component, an indenter, a sensor holder, and an acoustic sensor. The holder includes a first end and a second end opposite the first end. The first end defines a first cavity extending towards the second end. The component is positioned in the first cavity. The indenter is positioned adjacent to a portion of the component and applies a load onto the component. The sensor holder includes an upper portion, a lower portion, and a second cavity therein. The upper portion is coupled to the second end. The sensor is positioned within the second cavity. In some embodiments, the apparatus includes a rod coupled to the lower portion. The rod has a lower acoustic impedance than the sensor holder, thereby allowing sound waves to pass through the sensor holder and not be reflected back into the sensor.

Abstract: A photoacoustic imaging apparatus performs imaging of an optical absorber. The photoacoustic imaging apparatus includes a light source, a detector configured to detect an acoustic wave generated from the optical absorber that has absorbed energy of light emitted from the light source, and a signal processing unit configured to form an image of the optical absorber. The signal processing unit stores information indicating whether a rate of change in pressure of the acoustic wave detected by the detector is positive or negative before performing a waveform process on the acoustic wave.

Abstract: An arrangement and method for determining and monitoring the state of a rolling bearing, wherein a first sensor signal is captured in the form of a sound emission signal in a first frequency band in the ultrasonic range during operation of the rolling bearing, a second sensor signal is captured in a second frequency band of lower frequency in the ultrasonic range, a first characteristic value for recently occurred damage is determined from the shape of the first sensor signal, a second characteristic value for recently occurred damage is determined from the shape of the second sensor signal, and the state of the rolling bearing is determined by comparing the first characteristic value to a reference value dependent on the speed of the rolling bearing and dependent on the second characteristic value to at least one second reference value dependent on the speed of the rolling bearing.

Abstract: The structural integrity of a safe-life aircraft component on an aircraft is measured and assessed by a processing unit. The component includes a load-bearing metal element that is free from cracks. In the method, acoustic emissions generated in the metal element are converted into electronic signals. The acoustic emissions converted include relevant acoustic emissions resulting from changes in the structure of the element that make the element more susceptible to the formation of cracks. The electronic signals are set to a processing unit. The processing unit processes over time the signals in conjunction with stored reference data that allows a measure of the structural integrity to be made. Information providing a measure of the structural integrity of the aircraft component is outputted. Thus, deterioration of the structure of the component can be detected and monitored before a crack occurs.

Abstract: The invention relates to a method and to a device for sound emission analysis, wherein vibrations occurring during the use of a component, during the testing of a component or during the processing of a work piece by means of chipping, welding, forming, joining and/or separating or the like are registered and evaluated, wherein a vibration spectrum is recorded at different times or continuously and subjected to a multi-dimensional evaluation.

Abstract: An electrically passive device and method for in-situ acoustic emission, and/or releasing, sampling and/or measuring of a fluid or various material(s) is provided. The device may provide a robust timing mechanism to release, sample and/or perform measurements on a predefined schedule, and, in various embodiments, emits an acoustic signal sequence(s) that may be used for triangulation of the device position within, for example, a hydrocarbon reservoir or a living body.

Abstract: The present invention relates to a method for non-destructive investigation of the bottom of metallic tank structures, comprising the following steps: a) positioning an acoustic sensor at a point of contact between the tank wall and the bottom; b) submitting the structure to induced acoustic emission signals caused by a source of energy in close proximity with the position of the acoustic sensor; c) collecting data by the sensor and recording it; d) moving to a different position at an interval of 0.1-1.

Abstract: A computer implemented method, apparatus, and computer usable program code for testing a material. A signal is sent into the material using the transmitter. The signal has a frequency range that falls within a selected frequency range to form a transmitted signal. An actual response to the transmitted signal is received at a sensor. A simulated response of the material to the transmitted signal is generated using a functional model capable of modeling responses of the material to different frequency ranges falling within the selected frequency range. The simulated response is compared to the actual response to determine if a change has occurred in the material.

Abstract: A method of measuring an otoacoustic emission (OAE) is provided. The method comprises generating a frequency OAE graph with N plot lines, by performing frequency sweeping on N signals having different levels, wherein N is a natural number of at least 2; and when there are plot lines that overlap each other in the frequency OAE graph, compensating values of the N plot lines of the frequency OAE graph in a predetermined frequency section including a frequency section where the plot lines overlap each other.

Abstract: Apparatus for monitoring the cure of a bone cement material which is provided in a container. The apparatus includes a radiation source from which radiation is directed towards cement in the container and a sensor for detecting radiation from the radiation source which has passed through cement in the container, and for generating a signal according to the intensity of the detected radiation. A data processor is used in monitoring changes in the intensity of radiation that is detected by the sensor due to changes in the opacity of cement in the container to radiation from the source as the cement cures.

Abstract: The technology is based on subjecting the meat sample to an ultrasonic signal, of a specific frequency, and detects its reflected component. The detected signal will be analyzed using a fully developed and commercially available digital signal processing techniques to extracted ultrasonic parameters that can be directly related to elastic properties of the sample under investigation (piece of meat) and hence used to distinguish among the meats in question.

Abstract: According to one embodiment, a limpness detecting device includes a transmitting unit to irradiate an acoustic wave towards a conveyed sheet to excite a Lamb wave, a first receiving unit to detect a leaky wave of the Lamb wave emitted from a front surface of the sheet, a second receiving unit to detect a leaky wave of the Lamb wave emitted from a back surface of the sheet, a comparison data calculating unit to calculate comparison data based on the signal detected by the first receiving unit and the signal detected by the second receiving unit, and an intactness judgment unit to compare the comparison data calculated by the comparison data calculating unit with a preset standard value and judge whether the sheet is an intact bill or not, based on a result of the comparison.

Abstract: A new analytical technique, instrument and method of testing a material utilising same is provided. The method of analysing a test material comprises the steps of (vii) inducing an acoustic emission from a vessel containing a solvent and measuring said emissions; (viii) dissolving a known amount of the test material in the solvent; measuring changes in resonance and absorbance frequencies before and after dissolution to produce a broadband acoustic resonant dissolution emission profile.

Abstract: A system and method for determining the operating state of a curable composition utilizes an acoustic wave or signal transmitted into a container holding the composition. In one embodiment, characteristics of a reflected component of the acoustic signal are measured and correlated to pre-determined values indicative of one or more operating states, or degrees of curing, of the composition. In another embodiment, characteristics of a transmitted component of the acoustic signal are measured and correlated. The characteristics include, for example, the speed of sound through the curable composition or the attenuation of the acoustic signal reflected by or transmitted through the composition.

Abstract: A vibration recorder for detecting leaks in a pipeline network includes a sensor operable to receive vibration signals from a pipeline network, and a communication port connected to an automatic meter reader/transmitter (“AMRT”). A processor connected to the communication port and to the sensor is programmed to process the vibration signals and to send data regarding the processed vibration signals to the AMRT using the communication port. The vibration recorder may also include metering functions, and, in some implementations, may also incorporate the functions of the AMRT.

Abstract: A device and a method are provided for quality testing sheet metal parts, particularly deep-drawn parts. The device has a pulse generator (20) that excites the sheet metal part (2) to oscillate, a sound sensor (19) that picks up the sound profile, and an evaluation unit that compares the recorded sound profile with a reference curve and generates a signal with which the sheet metal parts are classified. To increase the suitability of a generic device or generic method for use in an automated production system, a testing device (4) is integrated into a press line in a clock cycle controlled fashion. Sheet metal parts whose recorded sound profile does not lie in a tolerance range of the reference curve can be eliminated by a sorting device.

Abstract: Disclosed is a vehicle sensor (4) for detecting impact sound, including a measured-value sensor (4.1) for detecting an impact sound. The measured-value sensor (4.1) includes several individual, separate measured-value sensing elements (4.1.x), each of which is coupled to a vehicle structure (5) in such a way that impact sound waves are transmitted by the vehicle structure (5) to the measured-value sensing elements (4.1.x).

Abstract: The present invention relates to a method and apparatus for non-invasive monitoring of brain density variations. At least two ultrasonic pulses having different frequencies are provided into the brain for transmission therethrough. The reflected ultrasonic pulses are then sensed and the sensed signal data are then processed for determining at least two phase differences between the phases of the at least two reflected ultrasonic pulses and the phases of the at least two provided ultrasonic pulses. A phase of at least a beat frequency is determined in dependence upon the at least two phase differences. Data indicative of a brain density variation are determined based on the at least two phase differences and the at least a beat frequency.

Abstract: An acoustic emission test sensor fixing device, comprising a radial positioning mechanism, supporting mechanisms, bases, acoustic emission test sensor mounting mechanisms, and parallelism adjusting members, wherein the supporting mechanism comprises a main supporting arm and an auxiliary supporting arm, with one end of the auxiliary supporting arm is fixedly connected to or hinged with the main supporting arm and the other end is provided with kink shaft members which are symmetrical about the auxiliary supporting arm; and the bases are provided with plugholes which form revolute pairs with the auxiliary supporting arm.

Abstract: A universal acoustic emission test sensor fixing device includes a radial positioning mechanism, supporting mechanisms, bases, acoustic emission test sensor mounting mechanisms, and parallelism adjusting members, in which the supporting mechanism includes a main supporting arm and an auxiliary supporting arm, with one end of the auxiliary supporting arm fixedly connected to or hinged with the main supporting arm and the other end being provided with a ball head, and a parallelism adjusting member mounting mechanism is provided at the joint of the main supporting arm and the auxiliary supporting arm, and the base is provided with a spherical hole.

Abstract: A structural integrity monitoring system includes a structure, at least two vibration monitoring devices mounted to the structure. Each of the at least two vibration monitoring devices outputs a vibration response signal. The structural integrity monitoring system also includes a controller operatively connected to each of the at least two vibration monitoring devices. The controller is configured to calculate a predicted vibration response based upon a vibration mode shape and the vibration response signal. The controller then compares the predicted vibration response against a measured vibration response to detect changes in the structure.

Abstract: A confocal photoacoustic microscopy system includes a laser configured to emit a light pulse, a focusing assembly configured to receive the light pulse and to focus the light pulse into an area inside an object, an ultrasonic transducer configured to receive acoustic waves emitted by the object in response to the light pulse, and an electronic system configured to process the acoustic waves and to generate an image of the area inside the object. The focusing assembly is further configured to focus the light pulse on the object in such a way that a focal point of the focusing assembly coincides with a focal point of the at least one ultrasonic transducer.

Abstract: Pulverizer coal flow pipes feed a mixture of air and coal to burners in electric utility coal fire facilities. A method and apparatus for sensing relative coal flow in the pipes uses acoustic emission (AE) sensors to detect flow in each pipe. Sensed relative flow in the pipes is used to balance flow in the pipes and to further adjust pipe coal flow. Sensed flow is used with control parameters of a furnace to maximize power plant efficiency and to ensure compliance with emissions requirements.

Abstract: A device (10) for measuring the running behavior of a gear pair having a rolling device (12) which comprises one spindle (15, 16) per gear (13, 14) and has at least one drive (17; 18) for driving one of the gears (13, 14). Furthermore, a structure-borne noise sensor (20), a sequence controller (30), and a speed sensor system (23, 24) are provided. The sequence controller (30) is designed in such way that a combined test of the gear pair may be performed, in which, in a first search run, a specific installation position is ascertained using structure-borne noise testing and subsequently a single-flank working test is performed at the specific installation position.

Abstract: Provided is a method of predicting failure in geotechnical structures using an AE method instead of a conventional displacement or stress measuring method, which belongs to a field of rock mechanics and geotechnical engineering. The method is a measurement technology for identifying signs of failure in geotechnical structures using Acoustic Emission (AE) signals generated by damage in the geotechnical structure and also providing management standard for failure prediction.

Abstract: Embodiments of methods and systems for monitoring stator winding vibration of a rotating electric machine are provided. According to one example embodiment, a system includes at least one sensor including at least one conductive sensor antenna deposited on a first side of at least one layer of a printed circuit board substrate and positioned to substantially face a stator winding, and a non-conductive shield mounted to an opposing side of the printed circuit board substrate and positioned to substantially face away from the stator winding. The system further includes an alternating current power source in communication with the sensor and operable to deliver current to the conductive sensor antenna. A signal processing unit may be in communication with the sensor, operable to measure a load on the sensor antenna and to transmit vibration data to a controller responsive to the load on the sensor antenna.

Abstract: An ultrasonic sensor includes an ultrasonic detecting element, an acoustic matching member, and an oscillation damping member. The ultrasonic detecting element detects an ultrasonic wave. The acoustic matching member has a receiving surface that is adapted on a side of the certain object to be exposed to a space, in which the detected body exists. The receiving surface receives the ultrasonic wave reflected by the detected body. The acoustic matching member is made of a material having an acoustic impedance larger than that of air and smaller than that of the ultrasonic detecting element. The oscillation damping member is disposed between an attachment portion and the acoustic matching member. The attachment portion is adapted for attaching the ultrasonic sensor to the certain object. The oscillation damping member damps transmission of oscillation from the certain object to the acoustic matching member.

Abstract: A device for estimating machining dimensions of a machine tool which employs tool members each being rotatably driven by a driving unit includes: a vibration sensor; a characteristics extracting unit for extracting amounts of characteristics from an output of the vibration sensor; a neural network for classifying the amounts of characteristics into categories; and a conversion unit. Amounts of characteristics of generated output by racing the tool member are used for training the neural network, and inputted again to the trained competitive learning neural network to excite neurons so that the relationships between Euclidean distances and machining dimensions of workpieces are registered in the conversion unit.

Abstract: A method for detection of a leak in a fluid affected component of a piston machine includes obtaining a vibration signal from a vibration sensor disposed proximate to at least one valve block of the piston machine. The vibration signal includes vibration generated by valves in the valve block. The method further includes presenting the obtained vibration signal for analysis by at least one of a human or a computer, analyzing the obtained vibration signal with respect to revealing a malfunction related to a fluid affected component of the piston machine, and selecting the obtained vibration signal emitted from the valve block during the closed periods of the valves for presentation.

Abstract: An automated crack detection system and method for determining a crack initiation potential of a vehicle closure includes a vehicle closure operatively mounted to a vehicle. One or more specific locations on the vehicle closure are identified for monitoring and one or more sensors are mounted on the vehicle closure at the one or more specific locations identified. A signal analyzer assembly is linked to the one or more sensors for receiving acoustic emission signals therefrom when the vehicle closure is repeatedly opened and closed. The signal analyzer assembly compares the signals received to a predetermined threshold to determine a crack initiation potential of said vehicle closure.

Abstract: There is described a diagnosis method and a system including a structure-born noise sensor which transmits, in a bandpass filtered manner, a measuring signal based on the mechanical resonance frequency and capacity thereof and on an inductance and an evaluating device in which the frequency, at which the measuring signal level exceeds a predetermined threshold value, is defined and which is used for producing an error signal, when the frequency exceeds a second predetermined threshold value. As far as the diagnosis performance requires a small number of electronic components and a low power supply, the diagnostic is integrated into existing devices, in particular into process instrumentation field devices for which a restricted quantity of operating power is available. The method and the system are used for identifying a valve leakage with the aid of an electro-pneumatic positional regulator.

Abstract: A method for measuring a mechanical property of a subject includes using an ultrasonic transducer to apply ultrasonic vibration pulses to a vibration origin in the subject in an on-off time sequence in order to impart a harmonic motion at a prescribed frequency to the subject, and when the vibration pulses are off, using the same transducer to apply ultrasonic detection pulses to a motion detection point and to receive echo signals therefrom in order to sense the harmonic motion on the subject at the motion detection point. From the harmonic signal information, a harmonic signal is detected and a characteristic such as amplitude or phase of the detected harmonic signal is measured. The mechanical property is calculated using the measured characteristic using for example a wave speed dispersion method.

Abstract: A method of monitoring integrity of a pump. The method may include recording timing information of the pump during operation while simultaneously sampling acoustic data with a high speed equidistant acquisition mechanism or at a rate based on the speed of the pump in operation. The acquisition of acoustic data is followed by evaluation thereof. Such techniques may improve resolution of acquired data while substantially increasing processor capacity for evaluation. A pump integrity monitor for carrying out such techniques is also described.

Abstract: Document inspection system comprising a transport system for transporting documents along a transport path (12) through an inspection station. At least one ultrasonic inspection apparatus at the inspection station, the apparatus including ultrasonic transmitting and receiving transducers (42,44) arranged on opposite sides of the transport path, and a processing system for monitoring ultrasonic signals received by the receiving transducer. An ultrasonic absorbing material (300) is provided around the transducers and facing the transport path for absorbing ultrasound reflected by a document. Document guide apparatus (312,314), having a lower coefficient of friction than the absorbing material, extends partially over the absorbing material (300) so as to prevent documents contacting the absorbing material in use while leaving the absorbing material exposed to the transport path at least adjacent the transducers.

Abstract: The present invention relates to a process to monitor unwanted formation of a polymer having internal mechanical strain wherein acoustic emission generated by said polymer formation is detected by one or more acoustic sensors attached to a piece of equipment. In a preferred embodiment the device to carry-out the process comprises: a resonant piezo-electric transducer attached to a piece of equipment, optionally a conditioner unit, connected to the previous transducer, said conditioner unit comprising means for filtering and an operational preamplifier, optionally a unit, connected to said conditioner unit, in which there is at least one adjustable threshold level (unless the conditioner unit comprises said adjustable threshold level), optionally a pulse counter connected to the conditioner unit comprising at least one adjustable threshold level. The invention is particularly useful for monitoring the unwanted popcorn polymers made from butadiene or isoprene.

Abstract: The present invention relates to an ultrasonic stress measurement method of measuring a residual stress of a measuring target layer in a measuring object using an ultrasonic wave, the method comprising, setting a plurality of vibration modes according to a number of degree of freedom of the measuring target layer in the measuring object, performing, for each vibration mode, a measurement operation of emitting an ultrasonic wave corresponding to the set vibration mode to the measuring target layer, receiving the ultrasonic wave reflected by the measuring target layer, and measuring an eigenfrequency of the measuring target layer, and measuring the residual stress of the measuring target layer based on plural measurement data of the eigenfrequency with respect to each vibration mode obtained by the measurement operation. The residual stress of the measuring object thus can be measured at higher accuracy.

Abstract: A parameter-free method to analyze sensor signals incorporates two or more of frequency demodulation, amplitude demodulation and phase demodulation of the raw signal data. The resulting signal is transformed to a frequency domain, and target fault characteristics from the demodulated signal are identified. The method is used to detect faults in bearings, gears and other mechanical components.

Abstract: An apparatus and methods for identifying a defect and/or an operating characteristic of a system being monitored (and/or one or more of the system's components) are described. In an embodiment, orthogonally related data monitored by two or more detectors may be fused to determine whether a component of a system is defective and/or malfunctioning. Additionally or alternatively, data from a first detector may be determined to be accurate using non-orthogonally related data outputted by a second detector. Both types of determinations may be made with minimal or no false indications, which lowers the cost of operating the system being monitored.

Abstract: A method for creating at least one input parameter for an algorithmic system to evaluate damage in a structure may include: (a) Determining a plurality of damage index factors using first signal information relating to a first signal transmitted through the structure before the damage is imposed, and second signal information relating to a second signal transmitted through the structure after the damage is imposed. (b) determining a plurality of condensed damage index factors using the plurality of damage index factors. (c) Correlating selected of the condensed damage index factors with selected measured dimensions relating to the damage to determine a correlation index for selected combinations of the condensed damage index factors and the dimensions. (d) Selecting the at least one input parameter from among the selected condensed damage index factors having a correlation index meeting at least one predetermined criterion.

Abstract: An ultrasonic sensor attached to a certain object, includes an ultrasonic detecting element, an acoustic matching member, and a reflection limiting member. The ultrasonic detecting element detects an ultrasonic wave. The acoustic matching member has a receiving surface that is adapted on a side of the certain object to face toward the detected body. The reflection limiting member is disposed to a side portion of the acoustic matching member between the receiving surface and an opposing surface of the acoustic matching member. The reflection limiting member limits the ultrasonic wave, which transmits inside the acoustic matching member, from being reflected by the side portion.

Abstract: A system for determining the source of vibration of a nipped roll assembly includes: a first substantially cylindrical roll; a mating structure positioned relative to the first roll to form a nip therewith; a plurality of annular nip condition sensor units mounted on the first roll; each of the annular nip condition sensor units being positioned at different axial locations along the first roll and configured to provide nip condition signals from the nip, the signals indicating a nip condition at multiple circumferential locations; and a processor associated with the sensor units that receives signals from the sensor units. The processor is configured to convert the signals from the sensor units into nip condition readings for the multiple circumferential locations at each axial location. Such a system can detect irregularities in a roll or the mating structure that can cause undesired vibration.

Abstract: There are provided a method and an apparatus for detecting damage to a high-pressure tank, with which a sign of failure of a high-pressure tank containing a high-pressure fluid can be detected early and non-destructively. An acoustic emission sensor (AE sensor) 1 is used for the non-destructive detection of a sign of failure that occurs upon filling a high-pressure tank 2 with a fluid. One AE signal detected by the AE sensor 1 is counted as one hit, the hit rate indicating the change in hits over time is found, and a sign of failure is detected from the change in the hit rate. When microcracks develop in the high-pressure tank 2, and a plurality of these microcracks join together and grow into a single, macroscopic crack, the hit rate of the AE signal no longer increases with respect to an increase in the internal pressure of the high-pressure tank 2, eventually reaching a saturation state. The hit rate in this saturation state is used to determine that there is a sign of failure.

Abstract: There is described a diagnosis method and system including a sensor for structure-borne noise which emits a measuring signal in a bandwidth-filtered manner due to its mechanical resonant frequency, capacitance and inductance. The system also includes an evaluation device in which the measuring signal is undersampled and which outputs an error signal should the undersampled measuring signal exceed a defined threshold value. The system requires only a small number of electronic components and only a little power supply capacity. The system thereby allows diagnosis to be carried out without complication in existing devices, especially in field devices of process instrumentation for which only a limited amount of operating power is available. The method and system are especially advantageous for the recognition of valve leakage with an electropneumatic position controller.

Abstract: The invention relates to a method for evaluating pressure containers made of a composite material by acoustic emission testing. The method comprises the steps: (a) determining a sufficient number of internal pressure-dependent acoustic emission characteristics (AE characteristics) of pressure containers from identical production that have been classified as being without defects in predetermined phases of a time-controlled pressure acting upon the pressure container (AE test procedure) with one or more acoustic emission channels (AE channels) using acoustic emission sensors (AE sensors) of a predetermined position (one AE characteristic per AE sensor or AE channel.

Abstract: A Stall Warning System (SWS) utilizing the detection and analysis of stress waves, (i.e., ultrasound) emitted by combustion and/or turbulent flow processes of an apparatus, such as a turbine engine, for example. Upon detection of an impending stall condition, the SWS can inform the operator, inform another electronic device (computer, etc.) and/or latch the event for review by maintenance personnel.

Abstract: An AE detector has an AE sensor and a destruction judging section. The destruction judging section judges it as a warning of destruction of a bearing when there are a predetermined number or more of points defined by parameters calculated based on signals from the AE sensor in a predetermined region of a parameter space defined by a plurality of parameters which can be created based on the signals from the AE sensor.