Abstract: A method of controlling a chemical reaction is disclosed. The method may include feeding a solution at a first flow rate into a reactor and detecting a sound in the reactor using a sound sensor that is adjacent to the reactor. The sound sensor may convert the sound into a sound signal. After the sound signal is acquired, it is compared to a stored sound signal or a stored sound threshold to detect a reaction event. The method may include adjusting the flow rate of solutions into the reactor in response to the reaction event.

Abstract: An elastic matrix determination method for a laminated iron core, which can optimally determine a shear modulus in two planes including a laminating direction of the laminated iron core included in an elastic matrix in a constitutive equation representing a stress-strain relationship used for vibration analysis, and also provided is a vibration analysis method. When performing a vibration analysis of a laminated iron core formed by laminating steel sheets using a constitutive equation representing a stress-strain relationship in a matrix representation, a shear modulus in two planes including a laminating direction of the laminated iron core included in an elastic matrix in the constitutive equation is determined depending on an average tightening pressure in the laminating direction of the laminated iron core.

Abstract: Embodiments of the present disclosure provide systems, methods, and computer-readable storage media configured to monitor wind turbines and detect damage to one or more components of the wind turbines, such as damage to the blades. The techniques disclosed herein may utilize sensors (e.g., acoustic sensors) disposed within air cavities of one or more blades of the wind turbines to detect acoustic signals or acoustic energy caused by corrosive impacts (e.g., wind, dust, rain, hail, lightning, etc.) to the wind turbine. Information associated with the acoustic signals may be provided to and received by a processor used to determine whether one or more of the blades of the wind turbines have been damaged. The techniques disclosed herein may facilitate real-time or near-real-time monitoring of wind turbines for damage, which may enable more efficient operation and maintenance of wind turbines.

Abstract: A pressure testing method capable of determining with a higher accuracy whether a high-pressure tank is deteriorated. The pressure testing method tests the high-pressure tank that includes a liner and a fiber-reinforced resin layer covering the outer surface of the liner and that has been used while repeating charge and discharge of gas to and from the inside thereof after undergoing a pressure resistance test conducted at a pressure resistance test pressure. The method increases the internal pressure of the high-pressure tank filled with gas to a test pressure that is lower than the pressure resistance test pressure, so that a plurality of AE waveforms is extracted from output waveforms of an AE sensor that detects AE waves generated in the high-pressure tank, and determines whether the high-pressure tank is deteriorated, on the basis of the extracted AE waveforms.

Abstract: A monitoring apparatus for a human body includes a node network with at least one motion sensor and at least one acoustic sensor. A processor is coupled to the node network, and receives motion information and acoustic information from the node network. The processor determines from the motion information and the acoustic information a source of acoustic emissions within the human body by analyzing the acoustic information in the time domain to identify an event envelope representing an acoustic event, determining a feature vector related to the event envelope, calculating a distance between the feature vector and each of a set of predetermined event silhouettes, and identifying one of the predetermined event silhouettes for which the distance is a minimum.

Abstract: One example method includes receiving information indicating a population of wild insects within a geographic region; determining a number of wild insects per unit area within the geographic region; placing, based on the number of wild insects per unit area, one or more insect release points based on the number of wild insects per unit area, each insect release point indicating a release of a predefined quantity of insects; and generating an insect release route through the geographic region, the insect release route passing through each insect release point.

Abstract: A new vibration test-cell that allows a static load to be applied simultaneously with lateral vibration coupled with in-situ microscopy that allows for the ability to open a fatigue crack up to a desired gap, as well as generate acoustic emission (AE) from vibration excitation, micro-fracture events are captured by the AE measurement while the physical observation of the crack faying surfaces is performed in-situ with an optical microscope embedded in the test cell.

Abstract: A system and method for determining when a sand separator should be purged to remove solids from the sand separator. The system can include an acoustic sensor which detects the frequency of audible sound coming from the inner chamber of the vessel and generate a signature signal representative of the frequency of audible sound. There is a processor connected to the acoustic sensor and configured to compare the signature signal with a set frequency range of audible sound which in turn generates a signal indicating when the signature frequency and the set frequency are in overlapping relationship.

Abstract: An ultrasonic inspection apparatus includes: an acquisition unit acquiring a signal indicating a fundamental wave and a second harmonic of an ultrasonic wave, which are obtained by the ultrasonic wave being scanned over an inspection object through a medium, at each scanning position; a calculation unit calculating a value obtained by dividing a second harmonic amplitude by a square of a fundamental wave amplitude, at each scanning position; and an output unit outputting information on a defect of the inspection object, based on the value obtained by dividing the second harmonic amplitude by the square of the fundamental wave amplitude.

Abstract: A system for determining a trigger amplitude indicating a precursor to a material fracture in a specimen under test includes a microphone converting acoustic emission emitted by the specimen under test into electrical signals. A load is exerted upon the specimen under test and the acoustic emission are emitted when the load causes the specimen under test to undergo deformation prior to the material fracture. A control module is in electrical communication with the microphone and executes instructions to monitor the electrical signals generated by the microphone and filter the electrical signals generated by the microphone. The control module converts the electrical signals generated by the microphone into individual frequency components based on a fast Fourier Transform (FFT). The individual frequency components each include a peak intensity. The control module determines the trigger amplitude based on the peak intensity of the individual frequency components of the FFT.

Abstract: Provided is a water leakage detection method for detecting water leakage of a water pipe by a water leakage detection apparatus that includes a processor and a display device. The method includes: a first procedure of the processor acquiring a water leakage detection result of the water pipe in a district metered area, the district metered area being a range to be measured by a flow meter; a second procedure of the processor acquiring a water leakage detection result of the water pipe obtained based on measurement data of a vibration sensor terminal attached to the water pipe; and a third procedure of the processor outputting, a screen for displaying the water leakage detection result obtained based on the measurement data of the flow meter together with the water leakage detection result obtained.

Abstract: A system for controlling an operation of a machine including a plurality of actuators assisting one or multiple tools to perform one or multiple tasks, in response to receiving an acoustic mixture of signals generated by the tool performing a task and by the plurality of actuators actuating the tool, submit the acoustic mixture of signals into a neural network trained to separate from the acoustic mixture a signal generated by the tool performing the task from signals generated by the actuators actuating the tool to extract the signal generated by the tool performing the task from the acoustic mixture of signals, analyze the extracted signal to produce a state of performance of the task, and execute a control action selected according to the state of performance of the task.

Abstract: A rotating machine abnormality detection device of an embodiment includes a non-contact acoustic emission sensor, an analyzer, and a diagnoser. The non-contact acoustic emission sensor, arranged at a position spaced away by a predetermined distance from a measurement target acting as a rotating member or a measurement target rotatably supporting the rotating member, is configured to detect acoustic emission that occurs during rotation of the measurement target or the rotating member supported by the measurement target and propagates in an atmosphere. The analyzer is configured to perform time-frequency analysis on a detection signal of the non-contact acoustic emission sensor. The diagnoser is configured to detect occurrence of a rotation abnormality when a frequency component equal to or larger than a predetermined threshold value is present in a predetermined frequency band, based on an analysis result of the analyzer.

Abstract: A method of disrupting the normal behavior and natural development cycle of wood-boring insects by applying mechanical vibrations and detecting wood-boring insects by monitoring their vibration patterns.

Abstract: An image processing device disclosed in the present specification includes a display control unit configured to display, on a display unit, an image obtained by visualizing functional information related to optical characteristics of a subject based on a photoacoustic signal obtained by receiving a photoacoustic wave generated in the subject by irradiating the subject with light, and a correction unit configured to correct the functional information of the image displayed on the display unit based on a first image value of the functional information of the image displayed on the display unit and a second image value of the functional information.

Abstract: A method for real time crush testing of proppants including loading proppant into an apparatus comprising: a body with a chamber to accept a piston and proppant; a pressure piston; a pressure transducer located in the bottom of the chamber; and a displacement sensor; compressing the proppant with the pressure; calculating the amount of proppant material in the proppant pack; increasing pressure on the proppant pack until the sample is crushed; calculating proppant strength from at least the displacement sensor data. An apparatus includes a body with a chamber to accept a piston and proppant; a pressure piston; a pressure transducer located in the bottom of the chamber; and a displacement sensor.

Abstract: Methods, apparatus, and articles of manufacture are disclosed. An example pre-amplifier includes a demodulator to generate an oscillating signal having a measurement center frequency, combine an acoustic emission signal and the oscillating signal to generate a sideband acoustic emission signal, sample spectral data of the sideband acoustic emission signal at an intermediate center frequency in an intermediate frequency bandwidth, and generate demodulated acoustic emission data based on a mapping of the sampled spectral data to the measurement center frequency, the measurement center frequency different from the intermediate center frequency, and a transmitter to transmit the demodulated acoustic emission data to a computing device.

Abstract: A system for monitoring and identifying states of a semiconductor device, the system including at least one acoustic sensor for sensing acoustic emission emitted by at least one semiconductor device operating at a voltage of less than or equal to 220 V, the at least one acoustic sensor outputting at least one acoustic emission signal and a signal processing unit for receiving the at least one acoustic emission signal from the at least one acoustic sensor and for analyzing the at least one acoustic emission signal, the signal processing unit providing an output based on the analyzing, the output being indicative at least of whether the at least one semiconductor device is in an abnormal operating state with respect to a normal operating state of the semiconductor device.

Abstract: A method for detecting a malfunction of an acoustic sensor coupled to an electrochemical generator includes applying an electrical signal at a given frequency and a given amplitude, termed the signal frequency and signal amplitude; measuring, by the acoustic sensor, an acoustic signal emitted by the electrochemical generator in response to the application of the electrical signal; and, when the amplitude of the acoustic signal is below a predetermined threshold value, and detecting a malfunction of the acoustic sensor.

Abstract: A method of detecting at least a blockage status in a porous member separating a measurement chamber of a device including a gas sensor positioned within the measurement chamber which is responsive to an analyte in an ambient environment to be sampled, includes emitting pressure waves from a pressure wave source which travel within the measurement chamber, measuring a first response via a first sensor responsive to pressure waves positioned at a first position within the measurement chamber, measuring a second response via a second sensor at a second position, different from the first position, and in fluid connection with the pressure wave source, determining the blockage status of the porous member based upon a functional relation of the first response and the second response.

Abstract: A multi-frequency acoustic velocity measurement device for a core includes: a fixing device, for fixing a core and heating and pressurizing the core according to a preset condition; a transmitting end acoustic wave probe, connected to a first end of a control unit and one end of the fixing device, and configured to transmit an acoustic wave signal to the core; a receiving end acoustic wave probe, connected to a second end of the control unit and the other end of the fixing device, and configured to receive the acoustic wave signal transmitted by the transmitting end acoustic wave probe; and the control unit, for controlling the transmitting end acoustic wave probe to transmit acoustic wave signals of different frequencies, receiving the acoustic wave signal received by the receiving end acoustic wave probe, and determining an acoustic velocity of the core according to the acoustic wave signal.

Abstract: A data storage unit 212 stores a plurality of pieces of abnormality data corresponding to operation state data of at least a robot in which an abnormality occurred in the past in association with environmental information and usage mode information. An abnormality data selection unit 218 narrows down the plurality of pieces of abnormality data stored in the data storage unit 212 to one or more pieces of the abnormality data based on the environmental information of a target robot and usage mode information of the target robot to select the abnormality data. A timing setting unit 220 sets a timing for notifying the abnormality sign based on the selected abnormality data and the operation state data corresponding to the selected abnormality data of the target robot. A notifying unit 126 notifies the abnormality sign related to the target robot at the timing set by the timing setting unit 220.

Abstract: A systematized multi-point sensors unit for a tire and a tire having the same are provided. More specifically, the systematized multi-point sensors unit includes: a sensor module composed of a plurality of sensors and attached onto an inner surface of a tire to monitor conditions of a tire and a road surface, and a connection member for connecting the plurality of sensors by wire, wherein the plurality of sensors are connected to each other by wire and arranged in a line in a manner of being perpendicular to a traveling direction of the tire.

Abstract: A method and apparatus for resolving individual signals in detector output data are disclosed. One inventive aspect includes a processing circuit configured to receive detector output data wherein the detector output data may be stepped data or non-stepped data; transform the detector output data to produce stepped data wherein the detector output data is received as non-stepped data; detect at least one signal at least partially based on the stepped data; and estimate a parameter associated with the signal, wherein estimating the parameter may preferably comprise estimating a signal energy or signal time of arrival associated with the signal.

Abstract: A machine bearing disposed on a rotatable member, such as may be present on a vehicle, is described. A method for monitoring a state of health of the machine bearing includes monitoring, via a microphone, an acoustic signal, and coincidently determining a rotational speed of the rotatable member associated with the machine bearing. The sound spectrum is correlated to the rotational speed of the rotating member, and a time-frequency analysis is executed to determine a sound spectrum. The sound spectrum is transformed to a residual spectrum. A first feature associated with a first frequency band and a second feature associated with a second frequency band are extracted from the residual spectrum. The state of health associated with the machine bearing is detected based upon the first and second features, and is communicated to a second controller.

Abstract: According to an embodiment, an apparatus for detecting a characteristic of a pump includes: a housing having a first planar surface and a second planar surface opposite the first planar surface, a mount structure located on the second planar surface, wherein the mount structure is configured to facilitate attachment of the apparatus on an external surface of the triplex pump, and wherein the mount structure avoids penetrating an inside surface of the triplex pump. Advantageously, apparatus is a non-invasive device and does not involve modifications to the pump nor opening the lid of the pump.

Abstract: A method for measuring fracture characteristics of adhesive polymeric material comprises: (i) bonding a sample to a rigid substrate; (ii) cooling the sample from a first temperature to a second temperature such that thermally-induced stresses are generated within the sample, wherein the thermally-induced stresses generate an inward-growing three-dimensional spiral crack within the sample; (iii) detecting, by three or more AE piezoelectric sensors, mechanical transient waves generated during development of the inward-growing three-dimensional spiral crack within the sample and determining the accurate 3D geometry of the spiral using source location technique; (iv) visualizing the two-dimensional spiral cracking pattern deposited on a surface of the rigid substrate and measuring the precise width of the crack; (v) determining, using the detected mechanical waves and the visualized deposited sample, AE-based fracture characteristics of the sample; and (vi) reporting the determined one or more fracture characteri

Abstract: A machine tool includes: a main spindle that holds a work piece; a tool holding unit that holds a tool for processing the work piece; a detection unit that detects vibration generated during processing of the work piece; and a processor that controls machining of the work piece performed by the tool, in which the processor compares a detected value detected by the detection unit with a predefined threshold value, interrupts the machining by releasing contact between the work piece and the tool at time of generation of chatter vibration or when there is a sign of the generation of the chatter vibration in which the detected value exceeds the threshold value, and analyzes the chatter vibration while the machining is being interrupted on basis of the detected value detected by the detection unit before the interruption.

Abstract: Bandwidth-selectable acoustic emission apparatus and methods for transmitting time-averaged signal data are described. An example apparatus includes an integrated external preamplifier device having a bandwidth-selectable analog filter and a data extractor. The integrated external preamplifier device is to receive an analog acoustic emission signal generated via an acoustic emission sensor operatively coupled to the integrated external preamplifier device. The bandwidth-selectable analog filter is to filter the analog acoustic emission signal based on a software-programmed bandwidth to generate a filtered analog acoustic emission signal. The data extractor is to extract a time-averaged analog signal from the filtered analog acoustic emission signal, and to transmit the time-averaged analog signal from the integrated external preamplifier device to an external data acquisition system.

Abstract: Integrated acoustic emission transducer apparatus and methods are described. An example integrated external preamplifier device includes a data extractor, a process variable determiner, a status indication determiner, and a presentation device. The integrated external preamplifier device receives an acoustic emission signal generated via an acoustic emission sensor operatively coupled to the integrated external preamplifier device. The data extractor extracts signal data from the acoustic emission signal. The process variable determiner determines process variable data based on the extracted signal data. The process variable data includes at least one of flow rate data, flow capacity data, flow area data, flow velocity data, mass accumulation data, or volume accumulation data. The status indication determiner determines status indication data based on the process variable data.

Abstract: A rig management system is disclosed. The rig management system may gather, from a set of sensors, data that includes: vibration data related to vibration of a valve associated with a pump of a hydraulic fracturing rig during operation of the pump, and pump speed data related to a speed of the pump during operation of the pump. The rig management system may process the data to identify a trend related to the vibration data, wherein the vibration data has been normalized based on the pump speed data. The rig management system may determine a remaining useful life of the valve based on the trend and threshold data that identifies a set of thresholds related to the vibration of the valve. The rig management system may determine that the remaining useful life satisfies a threshold. The rig management system may schedule an operation to be performed on the valve.

Abstract: A state monitoring system for monitoring state of a gear device having a plurality of gear pairs has a meshing frequency determination device. The meshing frequency determination device includes a maximum-peak-amplitude calculation unit that calculates a maximum peak amplitude from a detected meshing vibration, in estimated frequency ranges and a set harmonic region, and selects such estimated frequencies that a difference in maximum peak amplitude between a plurality of estimated frequency ranges, is less than or equal to a predetermined multiple, and a meshing frequency determination unit that determines an estimated frequency having a total value of maximum peak amplitudes calculated in the plurality of estimated frequency ranges, within a predetermined time, being the k-th (k is a natural number) greatest among the selected estimated frequencies, as a meshing frequency of a gear pair having the k-th highest tooth surface speed.

Abstract: The present disclosure discloses a detecting device and method for acoustic emission on high-frequency motion rubbing pair surface. A linear reciprocating slide system with high efficiency and high conductivity is designed based on the method. Reciprocating linear slide system is the main structure of the detection device which is is composed of probe plate, tight clips, vacuum cover, slip wire and insulation box. The reciprocating slide solves the problem of data distortion caused by high frequency jitter when connecting ordinary data lines, and can realize stable and reliable connection between high frequency reciprocating rubbing experiment and acoustic emission detection equipment. The acoustic emission probe on the surface of rubbing pair connects with the preamplifier by linear reciprocating slide.

Abstract: Circuitry for determining the direction of incidence of an acoustic signal in an integrated circuit. An electronic circuit includes a packaged integrated circuit. The packaged integrated circuit includes a die. The die includes a plurality of acoustic transducers spaced apart on the die, and a measurement circuit. The plurality of acoustic transducers includes at least a first acoustic transducer and a second acoustic transducer. The measurement circuit is coupled to at least the first acoustic transducer and the second acoustic transducer. The measurement circuit is configured to determine for the first acoustic transducer, a first time at which the first acoustic transducer detects an acoustic signal propagating in the die; and determine for the second acoustic transducer, a second time at which the second acoustic transducer detects the acoustic signal propagating in the die.

Abstract: A method for determining a quality of a friction stir welded seam is described. The method involves applying an impact to a welded plate and comparing its damping capacity with the damping capacity of a geometrically equivalent defect-free plate. Damping capacities that differ by a small percent difference indicate that the welded plate is also defect-free. This method is particularly advantageous when dealing with small defects, which produce miniscule changes in natural frequency which may not be measureable.

Abstract: A device for evaluating the condition of a wooden structure, including: a shaft; a distance sensor coupled to the shaft; and an image capture device coupled to the shaft, the distance sensor being configured to measure a location of the image capture device in the wooden structure.

Abstract: A method and apparatus of condition monitoring and detection of vibration generated from at least two different sources using a single sensor/transducer is provided. The method and apparatus provides switchably adapting signal processing, such as amplification and frequency filtering, to one at a time of the at least two different signal sources. An example of which is vibration sources. This adapts the analogue signal from the sensor/transducer to the analogue to digital converter and any further optional analogue signal processing, so that it is possible to maximize use of available dynamic range of these and without any saturation of these. Suitably, the signal processing to analyze the vibration signals is also appropriately adapted to the vibration source in question.

Abstract: Process to monitor unwanted formation of a polymer, having internal mechanical strain, wherein said formation of polymer generates acoustic emissions due to the sudden break of the polymer, wherein the number of said acoustic emissions increases over time when there is formation of said unwanted polymer formation, wherein said acoustic emissions is detected by a resonant piezo electric transducer having a resonant frequency centred on the second harmonic of said acoustic emission.

Abstract: Methods and systems for detecting pests, such as termites, in living organisms, such as trees. Certain embodiments of the current invention utilize time domain reflectometry to detect the pests. Other embodiments of the current invention utilize microwave-coupled transmission spectrometry antenna array transmitters, and receivers to detect the pests.

Abstract: A method and an apparatus for verifying compliance with a dental appliance therapy for a human patient is described. At least one parameter of a dental appliance worn by the human patient is periodically measured and compliance with the dental appliance therapy is determined by performing a spectral analysis of the measured parameter.

Abstract: Provided is a state diagnosis system, which is applied to a rolling guide device in which a moving member including an endless circulation path for rolling elements is freely movable along a track member, and which is configured to appropriately recognize a state of a rolling surface of the track member. The state diagnosis system includes: a sensor configured to detect a physical quantity exhibited when the moving member is moving along the track member; a signal processing unit configured to process an output signal from the sensor to output analysis data; and a determination processing unit configured to compare the analysis data with threshold value data to determine whether or not the rolling guide device has an abnormality.

Abstract: Methods and systems for conducting downhole operations including collecting downhole dynamic event data using a downhole tool, wherein the downhole dynamic event data is time-domain data, processing the collected downhole dynamic event data using a computing system located downhole to convert the time-domain data into frequency-domain data, and extracting digital filter coefficients from the frequency-domain data.

Abstract: Methods, systems, and media for providing sound level information for a particular location are provided. In some embodiments, the method comprises: receiving, from a user device, a request for sound level indications associated with a geographic region; in response to receiving the request, identifying a plurality of locations associated with the geographic region; identifying, for each location in the plurality of locations, at least one sound level reading corresponding to the location; generating, for each location in the plurality of locations, sound level indications based on the at least one sound level reading corresponding to the location; and transmitting at least one of the sound level indications and an identifier of at least one location in the plurality of locations corresponding to the at least one of the sound level indications to the user device.

Abstract: According to an embodiment, a detection system includes a plurality of first sensors, a second sensor, a first calculator, and a second calculator. Each of the first sensors is configured to detect an elastic wave generated from a structure, and convert the elastic wave into a detection signal. The second sensor is configured to detect a noise propagating from surroundings, and convert the noise into a reference signal. The first calculator is configured to calculate a plurality of difference detection signals based on the respective detection signals and the reference signal. The second calculator is configured to calculate a position of a generation source of the elastic wave from the plurality of difference detection signals.

Abstract: An elevator system (100) includes an elevator drive system (101) including a tension member (103) supporting an elevator car (106) under tension and a monitoring system (102). The monitoring system includes a vibration sensor (111) for detecting vibration of at least one of the tension member and the elevator car and an analysis unit (112) for determining a level of wear and life of the tension member based on the vibration of the tension member detected by the vibration sensor.

Abstract: Methods or systems for identifying seismic or acoustic signals of interest originating with moving motorized vehicles or footstep movement or stationary or moving machinery. A related system for monitoring an area includes a plurality of sensing devices each comprising a frame and a piezo-electric sensor element. A monitoring device is coupled to receive information from each of the sensing devices. One method includes providing a processing chain coupled to receive signal data from a sensor device which receives the signals, including a detection stage, a Joint Time Frequency (JTF) domain stage, and a classification stage. The detection stage identifies presence of signals that emerge from the background. The JTF domain stage estimates the state of the signals of interest over time. The classification stage assesses the previously derived information to form a decision about source identity. In one embodiment, the detector stage performs detections on a single cycle basis.

Abstract: According to an embodiment, a structure evaluation system includes a plurality of sensors, a position locator, a velocity calculator, and an evaluator. The sensors detect an elastic wave generated from a structure. The position locator derives a wave source distribution of the elastic waves generated from the structure, on the basis of the elastic waves. The velocity calculator derives a propagation velocity of the elastic wave generated from the structure, on the basis of the elastic waves. The evaluator evaluates the soundness of the structure on the basis of the wave source distribution and the propagation velocity of the elastic waves.

Abstract: Embodiments of the present invention provide a system and method for accurate, field-ready, non-destructive, and three-dimensional plant root characterization using acoustic signals. The system is portable, fast, precise, and can be used in field conditions, including moist soil, to visualize root structure or mass distribution, without damaging growing crops. The system may also be applied to characterize other underground objects, such as pipes, building foundations, archaeological artifacts, or mineral ores. During operation, the system generates a source acoustic signal. The system sends the source acoustic signal to an actuator acoustically coupled directly to a plant. The system obtains a response acoustic signal from an underground transducer monitoring a root of the plant. The system analyzes the response acoustic signal according to a model and based on the source acoustic signal. The system then determines, based on the analyzed response acoustic signal, a physical configuration of the plant root.

Abstract: Methods and systems for determining crack propagation length using a technique based on acoustic signature are disclosed. An acoustic signature is measured and recorded at a first location via acoustic wave generated by structural vibrations caused by a harmonic loading with predefined magnitude acted at a second location on the structure. Structure contains an unknown length of crack propagation inside. Unknown length is determined by comparing the measured and recorded acoustic signature with numerically-computed acoustic signatures stored in a database, which contains at least one relationship of the numerically-computed acoustic signatures versus respective crack propagation lengths at various stages of numerically-simulated crack propagation trajectory.

Abstract: A system for quality monitoring of additive manufacturing includes an acoustic emission (AE) sensor configured to be attached to an additive manufacturing substrate and to output a sensor signal indicative of acoustic vibrations received at the AE sensor and an AE module. The AE module is configured to receive the sensor signal from the AE sensor and process the sensor signal to determine at least one characteristic of an additive manufacturing process and/or an additively manufactured article.