Abstract: An acoustic apparatus adapted to operate in a gas filled space from a first side of an object to be measured for making a non-contact thickness measurement thereof includes an electro acoustic transducer, a transceiver coupled with the electro acoustic transducer and adapted to excite electro acoustic transducer to output an acoustic signal towards the object to be measured and receive an acoustic response signal therefrom, and a signal processor adapted to process the response signal and determine a thickness of the object. The electroacoustic transducer has a transducer-to-gas acoustic interface, and the transceiver is adapted to operate the electroacoustic transducer so as to emit into a gas filled gap an acoustic broad band pulse towards the object and to receive an acoustic resonance response signal in the acoustic response signal at a level that allows acquisition of the resonance response signal above a predetermined signal to noise level.

Abstract: A system for monitoring the free play in aircraft control surfaces includes one or more accelerometers secured in or on the aircraft control surfaces and a computer system connected to the one or more accelerometers and to one or more control surface actuators to selectively activated to selectively activate a control surface and send a reading from the control surface to the computer system. The computer system includes means to plot the readings from the one or more accelerometers on the control surfaces to plot a curve of the free play in the selected control surface. The method of the invention utilizes the one or more accelerometers placed in or on the aircraft control surfaces and connects them to the aircraft's flight control computer or a similar computer to receive signals originated by vibrating the control surfaces and plotting curves of the free play measured in the control surfaces.

Abstract: A method for identifying an unfolded non-synchronous blade vibration frequency in blades on a rotating rotor using a plurality of probes spaced from each other about the rotor. A set of data is acquired from the probes during a predetermined number of rotor revolutions and is processed using a Fourier analysis to generate an output representative of frequencies and phase shift angles corresponding to blade vibrations. The phase shift angles are used to identify a subharmonic for a blade vibration frequency to provide an output identifying the vibration frequency. A space dispersion and time dispersion of probes is described to increase the accuracy of the subharmonic determination using the phase shift angles.

Abstract: A abnormality diagnosing apparatus used in a machine equipment including a rotating or sliding part relative to a stationary member includes a detecting portion 31 fixed to the rotating or sliding part or the stationary member and including a vibration sensor 32 and a temperature sensor 33, and a signal processing portion 81 for determining a state of the part from a detecting signal outputted by the detecting portion 31. The signal processing portion 81 determines presence or absence of a abnormality, or presence or absence of the abnormality and a degree of a damage of the part based on a combination of a measured result by the vibration sensor 32 and a measured result by the temperature sensor 33.

Abstract: A resonance shear measuring method capable of simple and rapid measurement by obtaining a resonance shear curve through Fourier transformation of a damping curve of an oscillation on one side surface of a sample during measurement of shear response from the sample is provided.

Abstract: Systems and methods for analyzing the resonant frequency of vibratory wires within vibratory wire gauges. The resonant frequency of the vibrating wire is determined by using an interface that digitizes the response of an excited wire in the gauge. A transform then converts the digitized data into a frequency spectrum. The resulting spectrum is used to estimate the resonant frequency of the vibrating wire. The resulting measurement or estimate of the resonant frequency can be used to measure or determine some physical characteristic of the device or structure or system connected to the gauge.

Abstract: The invention relates to a method of detecting damage in a bearing supporting at least one rotary shaft of an engine in rotation, the method consisting in: defining a measurement period corresponding to a range of speeds of rotation of the shaft during renewable activity at low speeds of operation of the engine; acquiring over the entire measurement period a vibratory signal representative of acceleration of components of the engine; sampling the vibratory signal as a function of the speed of rotation of the shaft during the measurement period; transforming the sampled vibratory signal into a frequency signal to obtain frequency spectrum lines as a function of the speed of rotation of the shaft; calculating the mean of the amplitudes of the spectrum lines; determining amplitude peaks around multiples of the theoretical frequency of a damaged roller; calculating the ratio between each amplitude peak and the amplitude level determined for a sound bearing; and comparing the ratio that is obtained with at least o

Abstract: The present invention provides a system and method for monitoring vibration of a power transformer. The system comprises at least one vibration sensor operably mounted to the outer case of a transformer for sensing vibration of the power transformer; a spectrum analyzer for processing the vibration signal from the vibration sensor, the spectrum analyzer generating a frequency spectrum of the vibration signal and calculating a velocity rating from the frequency spectrum; a diagnosing means for evaluating the velocity rating of the vibration signal, the diagnosing means assigning a vibration grade for each velocity rating, the diagnosing means finding the maximum velocity rating; and a means for dispatching a control message to an operator when the maximum velocity rating reaches a threshold value. It can be appreciated that the mechanical health of a large-sized transformer can be managed in a systematic and efficient manner during its operation.

Abstract: An impact elastic wave test is conducted to measure propagating waves in a pipe to be examined, a frequency spectrum of the propagating waves is analyzed, and at least a spectral area value in a first frequency region and a spectral area value in a second frequency region of the frequency spectrum are evaluated, thereby determining a type of a deteriorated state of the buried pipe.

Abstract: Provided are an envelope processor 103, for obtaining an envelope for a detected signal; a FFT unit 104, for converting the envelope into a frequency spectrum; a peak detector 105, for smoothing the frequency spectrum by calculating a moving average, for further performing smoothing and differentiation for the spectrum, and detecting, as peaks, frequency points at which a sign of a differential coefficient is changed from positive to negative, for extracting peaks having a predetermined threshold value or greater, and for sorting the extracted peaks and detecting upper peaks; and a diagnosis processor T, for diagnosing an abnormality based on the detected peaks.

Abstract: A method for identifying an unfolded non-synchronous blade vibration frequency in blades on a rotating rotor using a plurality of probes spaced from each other about the rotor. A set of data is acquired from the probes during a predetermined number of rotor revolutions and is processed using a Fourier analysis to generate an output representative of frequencies and phase shift angles corresponding to blade vibrations. The phase shift angles are used to identify a subharmonic for a blade vibration frequency to provide an output identifying the vibration frequency. A space dispersion and time dispersion of probes is described to increase the accuracy of the subharmonic determination using the phase shift angles.

Abstract: Methods and systems for detecting wafer shift/slide in a semiconductor process chamber have been disclosed. The vibration amplitude is measured in terms of acceleration because an increase in vibrational acceleration correlates with an increase of displacement of a wafer. The vibration of a chamber is measured. External vibratory forces acting on the chamber may be transmitted to the wafer inside the chamber. The methods/systems determine if there is a net resultant force that may cause an unconstrained wafer to move from its original position in a chamber by measuring the relative chamber vibrations in three orthogonal directions. A tri-axial or three uni-axial accelerometers are mounted on a preferably exterior wall of the chamber to measure its vibration amplitude. The signal obtained as a function of time is then compared against a predetermined alarm amplitude to provide notification for corrective action.

Abstract: Degradation of the lubricant due to contamination of the lubricant with wear particles or moisture, which greatly affects the service life of rolling bearings, can be detected in a cost-effective manner through the use of a resonance frequency band signal or high-frequency signal of an accelerometer, and the service life of a rolling bearing can be estimated with high precision at an early stage on the basis of the detected state of the wear particles and lubricant.

Abstract: A system may be used to indicate a need for replacement of a vibrating structure and includes a sensor, an indicator, and a processor. The sensor senses a frequency of vibration of the vibrating structure. The indicator is controlled to provide an indication of the need for replacement of the vibrating structure. The processor compares the frequency of vibration of the vibrating structure to data that relates the vibration frequency of the vibrating structure to fatigue damage of the vibrating structure, and controls the indicator based on the comparison.

Abstract: An apparatus surely measures the vibration characteristic of a head gimbal assembly and has a wide range of resonance frequencies to be set, the apparatus has a first laser Doppler vibrometer to detect a vibration velocity of a shaker, a second laser Doppler vibrometer to detect a vibration velocity of a head of the head gimbal assembly fixed to a fixture, and a reflection mirror to orthogonally reflect a laser beam emitted from the first laser Doppler vibrometer toward the fixture fixed to the shaker, and the apparatus finds the vibration characteristic of the head gimbal assembly according to the detected vibration velocities.

Abstract: The method decomposes the radio frequency signal into sub-bands by filtering, for example with a time-frequency transform. From the coefficients acquired through decomposition a matrix of spectral coefficients is obtained, from which local estimators are obtained, constituted in particular by the coefficients of the interpolating polynomials. The statistical distribution of the local estimators is evaluated in windows overlaid on the ultrasound frame. The conformation of the distribution histograms of the spectral coefficients provides a parameter which, combined with the local estimators, provides weighted local estimators, which contain spectral information useful in the identification of specific structures in the organ subjected to ultrasound analysis.

Abstract: A diagnostic vibration analyzing system and method for measuring and characterizing both linear and torsional vibrations in a vehicle or a piece of industrial equipment (collectively a “vehicle”). An electronic control unit and a plurality of sensors cooperate to measure accelerations sensed by a vehicle operator. These measured accelerations, when combined with sensed rotational velocities, can be used to pinpoint likely sources of driveline vibrations. Once the sources of driveline vibrations are identified, they are graphically displayed to a user for remedial action.

Abstract: A method for detecting squeaking noises within a sound signal generated during operation of a motor vehicle or during operation of a component thereof is described; in this method the sound signal is detected; an amplitude spectrum of the sound signal representing the amplitude distribution in a frequency range is generated at a minimum of two points in time and the existence of a squeaking noise is detected by analysis of the at least two amplitude spectra.

Abstract: A chatter boundary system includes a measuring module, a comparison module, and a boundary module. The measuring module measures and collects samples of undulations in a manufactured part. The comparison module classifies a sound signal generated by the undulations as either noisy or quiet. The boundary module determines a continuous boundary between the noisy and quiet undulations based on the samples and the sound signal.

Abstract: A method of analyzing variations in an indicator of the behavior of a mechanism, in which noise is extracted, and any discontinuities from an indicator in order to obtain a trend, variations in the trend are compared with one or more reference values; and a fault of the mechanism is indicated as a function of the result of the comparison. Any outlier data in the indicated data are search for and subtracted, and any edge data are extracted from the data obtained from the search operation.

Abstract: A method for analyzing vibration including: acquiring a vibration signal; isolating a vibration signal event in the acquired signal; determining a frequency of a damped sinusoid of the vibration signal event, wherein the damped sinusoid characterizes the vibration signal event, and using the characteristic damped sinusoid to identify an occurrence of the vibration signal event in another vibration signal.

Abstract: A method and system provides for acoustic sensing of structures, including a general shape and/or configuration of the structure and movement within the structure. Acoustic waves are used to characterize structures, including any activity within. As waves from a sound source travel into the structure, they resonate within cavities and connecting tunnels or halls. This acoustic resonance is received at an acoustic receiver. The received signal is analyzed in comparison to the generated signal, and properties of the structure are determined, including the size and shape of the structure, as well as movement of objects within the structure.

Abstract: Parametric ultrasonic measurements which characterize the structure of tissue, using information from an ultrasonic signal beyond amplitude information, are obtained by combining multiple ultrasonic signals acquired at different angles, thereby reducing the variance of the calculations. Such angular compounding may be applied to detecting scatterer size, spacing, density, and attenuation.

Abstract: A device for measuring thickness of an object has a vibration generator for generating vibrations in the object, a vibration detector for detecting vibrations generated in the object by the vibration generator and a frequency analyzer for calculating resonance frequency of the object. The vibration generator includes a light-emitting part which emits light towards the object to irradiate and to be absorbed by the object. A plurality of vibration detectors may be used and the frequency analyzer may include a sound speed analyzer for calculating speed of sound inside the object from vibrations detected by these plurality of vibration detectors.

Abstract: A process is performed for testing the quality of a unit such as an electromotor, which has at least one mobile part, which is mobile within a given frequency range with varying frequencies and is capable of exciting the unit to oscillate. In the method, a frequency of the mobile part at least within a first interval of the frequency range is varied with a first rate of change. The frequency of the mobile part within at least a second interval of the frequency range is varied with a second rate of change. The second rate of change is lower than the first rate of change. The oscillation amplitude of the unit is recorded and the unit is assessed as useful or unusable by evaluation of the recorded oscillation amplitude.

Abstract: A measuring system for structure-born noise measurement of machine elements in machine housings. The measuring system is fixed to the machine housing via a lubrication hold opening. A mounting pin with a continuous bore hole. A housing receives a printed circuit board provided with electronic components for signal evaluation. A vibration snesor and vibration sensor housing rotationally mounted in relation to the mounting pin when the mounting pin is screwed into the lubrication hold opening. The vibration sensor housing is rotationally fixed to the machine housing in a non-positive fit via a metal bushing when the mounting pin is screwed in an end position. The vibration sensor is located adjacent to the metal bushing whereby structure-born noise is directly transferred from the machine housing to the vibration sensor via the metal bushing.

Abstract: A method for determining vibration amplitude limits of a mechanical device. The method comprises identifying a mechanical device and a frequency range for a spectrum to be analyzed, retrieving vibration spectra comprising individual spectrum for the mechanical device and the frequency range, calculating frequency for the individual spectrum, and identifying the individual spectrum with the smallest number of frequency lines. In addition, the method comprises calculating noise bandwidths and a largest noise bandwidth, removing outlier data, calculating conditional kernel density, and calculating vibration amplitude limits to detect faults in the mechanical device.

Abstract: In a method and apparatus for engraving printing cylinders in an electronic engraving machine, an engraving control signal is formed from an image signal that represents tonal values of cups to be engraved and from a periodic raster signal for generating a printing raster. An engraving stylus of an engraving element controlled by the engraving control signal engraves a printing form in the form of cups arranged in the printing raster in a rotating printing cylinder. For checking of the functionability of the engraving stylus, test cups are engraved simultaneously when engraving the printing form. A respective measurement interval is defined for selected test cups. The raster signal is respectively eliminated from the engraving control signal for the duration of the measurement interval, and the remaining engraving control signal is investigated for harmonics characteristic of damage to the engraving stylus.

Abstract: In a method and apparatus for engraving printing cylinders in an electronic engraving machine, an engraving control signal is formed from an image signal, which represents the tonal values of the cups to be engraved, and from a raster signal for generating a printing raster. An engraving stylus of an engraving element controlled by the engraving control signal engraves a printing form engraving line by engraving line in the form of cups arranged in the printing raster in a rotating printing cylinder. Functionability of the engraving stylus is continuously checked during engraving of the printing cylinder by a digital filtering of the engraving control signal in an engraving stylus monitoring device. When damage is found, a control signal is generated that aborts the engraving, or acoustically or optically signals the identified damage to the engraving stylus.

Abstract: A configurable vibration sensor having a sensor circuit, an analog-to-digital converter and a processor is provided. The sensor circuit employs a vibration sensing element and a variable bandwidth filter controllable by the processor. In addition to the variable bandwidth filter, other configurable elements may also be employed in the sensor circuit, including a variable gain amplifier. These configurable elements allow the configurable vibration sensor to be configured for different vibration measurement applications when measuring vibrations from vibrating structures such as machinery and the like.

Abstract: Determining whether a device is defective by analyzing the sound signals generated by the device. Digital samples are generated to represent the sound signals. Digital samples are transformed from the time domain to the frequency domain to generate a frequency spectrum. By comparing the levels of intensity at a corresponding frequency to the threshold levels of intensity, defective devices can be determined.

Abstract: A sensor circuit, method, and system for conversion of a high-impedance, broad frequency range signal from a transducer into two low-impedance signals, one containing high-frequency components and another containing low-frequency components of the input signal. The transducer can be a piezoelectric (PE) transducer transforming motion or vibration into a high-impedance electrical signal with a broad frequency range. A low-frequency circuit output can contain the frequencies in the linear region of the transducer's frequency band. The high-frequency output can contain the natural resonance frequency of the transducer. The circuit includes a low-frequency filter amplifier module and a high-frequency filter amplifier module, both amplifier modules having negative feedback, high input impedance, and low output impedance; the outputs may include a DC bias. The circuit may also include a source follower isolating the filter amplifier modules from each other.

Abstract: An acoustic wave sensor utilizes one or more acoustic waves trapped in an acoustic wave cavity to detect the presence of one or more substances on a surface of the acoustic wave cavity. To detect the presence of ice, a trapped torsional acoustic wave is used. To detect water, an acoustic wave with flexural or compressional components is used. The sensor includes a number of transducers adjacent the acoustic wave cavity where a controller drives different sets of the transducers to generate different acoustic waves.

Abstract: A low cost, low power and lightweight swept sine wave analysis system that is affordable to engineers, university laboratories and students, providing accurate magnitude and phase response measurements over a wide bandwidth is described. An analog mixer mixes a local oscillator signal with an amplified input signal allowing AC signal coupling between input stages. This minimizes errors due to DC and low frequency drift. A computer graphical interface is used for controlling the acquisition hardware in real time, displaying results on the computer screen, and making the graphical results and numerical results immediately available for inclusion in documentation or spreadsheet applications.

Abstract: In a method for determining the state of a road during driving of a motor vehicle, the sound which is generated when a vehicle tire rolls on an underlying surface is sensed. A frequency signal is determined by means of a sound level signal which describes the sound, and is divided into at least two sub-zones by means of at least one limiting frequency. The sub-zones are each assigned to an associated frequency band, and an intensity value is determined for each of at least two frequency bands from the assigned sub-zone of the frequency signal. The intensity value is characteristic of the sound intensity which is present in a frequency band. An intensity ratio is formed from two intensity values by dividing the first intensity value of the first frequency band by the second intensity value of the second frequency band, and is used to determine the state of a road.

Abstract: A system and method for determining at least one parameter related to a train traversing on a railway track is provided.

Abstract: A tool and method to identify a defect in a vehicle through a vibration frequency is provided. To identify the defect in a vehicle, a sensor senses a vibration frequency and generates a signal in response to the vibration frequency. In addition, a signal spectrum analyzer communicates with the sensor and identifies the defect in response to the signal.

Abstract: A method and a device for detection, classification and densimetric quantification of grain-eating insects, of one or several families of insects simultaneously present, in stocks of cereals and the like, which includes detecting insects through noises and sound and/or infrasonic vibrations emitted by the insects. It also includes carrying out the following operations: recording the real noises in the stock, eliminating known spurious noises, detecting on the resulting envelope energy curve windows corresponding to energy peaks and determining therefrom the mean frequency, the spectral width and the global energy, comparing the mean frequency and the width of each of the windows to that of windows with similar known and listed characteristics, so as to operate a taxonomic classification, finally, comparing the mean frequency and the global energy of each of the windows, to those of windows with known and listed characteristics, to operate a densimetric quanitification.

Abstract: A device for the testing and monitoring of the function of a shock wave or pressure wave source is provided. The testing and monitoring device is characterized in that a passive non-linear transmission element transforms very short shock wave pulses received by it, the shock wave pulses typically having pulse durations lasting a few microseconds, into a considerably lower frequency range, whose oscillations are then sensed and evaluated.

Abstract: An output signal that accords with a rotation speed of a brake rotor of a respective wheel is output by a vehicle wheel speed sensor. A noise frequency identification portion identifies a frequency component that corresponds to brake noise from this output signal. It is possible, for example, to identify a frequency component that corresponds to brake squeal by performing fast Fourier transform (FFT) calculation for the vehicle wheel speed. Further, a noise detection portion determines that brake noise is being generated when the frequency component identified by the noise frequency identification portion is equal to or more than a predetermined value.

Abstract: A method and apparatus for sensing and measuring stress waves. The method comprises the steps of: a.) sensing motion, where the motion comprises a stress wave component and a vibration component; b.) separating the stress wave component from the vibration component with a high pass filter to create a signal proportional to the stress wave; c.) amplifying the signal to create an amplified signal; d.) processing the amplified signal with a sample and hold peak detector over a predetermined interval of time to determine peaks of the amplified signal over said predetermined period of time; e.) creating an output signal proportional to the determined peaks of the amplified signal; and, f.) repeating steps d.) and e.). The invention also includes an apparatus for implementing the method of the invention.

Abstract: A system for monitoring mechanical waves from a machine which in operation has moving particulate matter therein, the system including at least one sensor located on the machine at a location away from the central axis of the machine, the sensors being for sensing acoustic waves and including a transmitter for transmitting signals representing the sensed mechanical waves to a receiver at a location remote from the sensor(s), a data processor connected to the receiver for receiving signals from the receiver which signals represent the mechanical waves and processing the signals to produce output signals for display on a display means, wherein the output signals for display represent one or more parameters indicative of mechanical waves emitted from the machine over a predetermined period of time.

Abstract: Sensor assembly for measuring a load on a bearing having at least one bearing ring (11), the at least one bearing being provided with a cavity (12) for holding the sensor assembly. The sensor assembly comprises a series mounting between opposing sides (17, 18) of the cavity (12), the series mounting comprising a piezoelectric plate (16) and a spring (19) with spring stiffness k. Alternatively, the sensor assembly further comprises a body (14) with mass in mounted between the piezoelectric plate (16) and the spring (13), to allow simultaneous load measurement and health monitoring.

Abstract: A system and method for determining at least one parameter related to a train traversing on a railway track is provided.

Abstract: A micro acoustic spectrum analyzer for determining the frequency components of a fluctuating sound signal comprises a microphone to pick up the fluctuating sound signal and produce an alternating current electrical signal; at least one microfabricated resonator, each resonator having a different resonant frequency, that vibrate in response to the alternating current electrical signal; and at least one detector to detect the vibration of the microfabricated resonators. The micro acoustic spectrum analyzer can further comprise a mixer to mix a reference signal with the alternating current electrical signal from the microphone to shift the frequency spectrum to a frequency range that is a better matched to the resonant frequencies of the microfabricated resonators. The micro acoustic spectrum analyzer can be designed specifically for portability, size, cost, accuracy, speed, power requirements, and use in a harsh environment.

Abstract: A method for compensating for a mechanical oscillation which has a frequency spectrum which can be approximately represented by a number of discrete frequency components, at a machine shaft via at least one actuator acting directly or indirectly upon the machine shaft. At least upon one of the discrete frequency components of the mechanical oscillation is superposed by the actuator, independently of the other frequency components, at least one substantially harmonic torque of the same frequency having a specific amplitude and phase in such a manner that the amplitude of the oscillation of the machine shaft at the this frequency is reduced.

Abstract: Output-only modal testing of an object. Vibrations are excited in said object and measured by a number of vibration sensitive detectors. From the data of the measurements, a spectral density matrix function is determined. From this density matrix, auto spectral densities for the individual modes are identified performing a decomposition based on the Singular Value Decomposition technique. From the auto spectral densities of the individual modes, natural frequencies and damping ratios for the modes can be estimated, and from the singular vectors of the Singular Value Decomposition, the modes shapes can be estimated.

Abstract: A method and device for detecting stenoses in a tubular line system during an extracorporeal hemotherapy. The tubular line system has an arterial branch going out from the patient and leading to a hemotherapeutic unit, and a venous branch going out from the hemotherapeutic unit and leading to the patient, where an oscillating pressure signal is generated in the tubular line system, and the oscillating pressure signal is measured. To detect stenoses, the frequency spectrum of the oscillating pressure signal is analyzed, in response to a change in the frequency spectrum. This method is based on the principle that, in response to the existence of a stenosis, the dynamic performance of the tubular line system changes, the higher frequency components of the pressure signal generated by the rollers of the blood pump, which propagates across the tubular line system, being attenuated due to the compliance of the line system.

Abstract: A diagnostic vibration analyzing system and method for measuring and characterizing the torsional vibrations in a vehicle or a piece of industrial equipment (collectively a “vehicle”). An electronic control unit and sensor cooperate to measure speed fluctuations occurring between the passing of adjacent teeth of a rotating gear. These time measurements are the basis for displacement, velocity and acceleration calculations which, combined with driveshaft rotational order information, can be used to pinpoint the source of excessive driveline torsional vibrations. The use of multiple sensors can maximize per test the information available for analysis. The use of multiple sensors in a substantially simultaneous manner can isolate particular components in the tested vehicle.

Abstract: A method for compensating for a mechanical oscillation which has a frequency spectrum which can be approximately represented by a number of discrete frequency components, at a machine shaft via at least one actuator acting directly or indirectly upon the machine shaft. At least upon one of the discrete frequency components of the mechanical oscillation is superposed by the actuator, independently of the other frequency components, at least one substantially harmonic torque of the same frequency having a specific amplitude and phase in such a manner that the amplitude of the oscillation of the machine shaft at the this frequency is reduced.