Abstract: The invention relates to a method for evaluating the condition of a machine (100) with a measuring point (90), which method is performed by a movable analysis apparatus (30). The method comprises the steps of producing a condition value, by means of measuring at the measuring point, which condition value is dependent on the actual condition of the machine, and storing the condition value in a writable information carrier (120) which is placed by, or in the vicinity of, the measuring point (90) so that the condition value subsequently can be used as a reference condition value. The invention further relates to an apparatus for performing the method and a device for cooperating with the analysis apparatus and for mounting by a measuring point on the machine (100).

Abstract: The present invention provides a method for signal vibration alert. The method of the present invention recognizes significant substantial swerves and corresponding substantial edge-to-edge differences by eliminating the adverse effect of noise among signals generated by an apparatus. When the frequency of the substantial edge-to-edge differences that exceed an acceptable range of the frequency limit is too large, the method of the present invention automatically generates an alert to indicate aberration in the apparatus such that the monitoring staff is informed and allowed to take necessary measures responding to the aberration.

Abstract: A method and system for monitoring the condition of a bearing mounted on a rotating shaft, particularly one present in an aircraft gas turbine engine, where the vibration sensor that monitors the bearing is remote therefrom but proximate to the rotating shaft. The vibration sensor obtains a broadband signal having frequencies that include the bearing defect peak of the monitored bearing. The broadband signal is analyzed to identify the presence of the bearing defect peak. If the bearing defect peak is present, the amplitude of this peak is quantified to determine whether degradation of the monitored bearing has at least reached a threshold criteria previously established.

Abstract: Stationary sensors are used to measure periodically the vibratory motions of portions of a body spinning in front of them, such as blades, and to try to determine their natural frequencies by spectral analyses. The sensors are collected together in several networks of different numbers and the determination includes a comparison of the spectra of the different networks via different operations of selection and rejection of lines. The process appreciably pushes back the limit of unambiguous frequency detection.

Abstract: A system for remote diagnosis of the state of wear of the suction and delivery valves of reciprocating compressors comprises at least one piezoelectric seismic sensor, applied to each cylinder of the compressor. The sensor transforms the vibrations generated by the noise of the valves into an electric signal. By appropriate amplification and filtering, the envelope of the resulting narrow band signal is obtained. The signal obtained is then digitized, and transmitted to a remote diagnostics center for monitoring.

Abstract: An externally-powerable sensor is described for detecting ultrasonic energy and for providing an accurate indication of the level of such energy to an external monitoring device over a wide dynamic range. A first electrical signal proportional to the detected ultrasonic energy is chopped by the output of a free-running multivibrator to generate a signal having a frequency differing from the frequency of the first signal by an amount within the audio frequency range. Such difference signal is selectively amplified to concentrate the spectral energy of the difference component in a lower portion of the audio range. A low pass filter extracts, from the so-concentrated difference signal, a modified audio signal whose frequency content is at the lower end, illustratively 0-6 KHz, of the spectrum of the concentrated difference signal. The output of the low pass filter is processed to generate a DC output current that is proportional to the detected ultrasonic energy level.

Abstract: The invention relates to a diagnostic system and method, especially for a valve (2) that can be actuated by a positioner (9) via a drive (6). The system utilizes a sensor (12) for recording structure-related sound and has a device (14) for evaluating a recorded measurement signal (13). A spectral region greater than 50 kHz is evaluated for conducting fault recognition. A fault indication signal is generated if the intensity of the measurement signal in this spectral region exceeds a defined threshold value. The sound caused by cavitation is primarily evaluated for conducting fault recognition.

Abstract: An ultrasound imaging method forms an image of an object using signals reflected from the object after transmitting an ultrasound pulse to the object. In the method, at a first step, a predetermined first spread spectrum signal is converted to the ultrasound signal at one or more transducers and the ultrasound signal is transmitted to the object. At a second step, pulse compression is performed on a reflected signal of the ultrasound signal reflected from the object to form a pulse compressed signal. And the pulse compressed signal is processed to produce a receive-focused signal and the image of the object from the receive-focused signal is generated.

Abstract: A method for detecting transverse mode vibrations in an ultrasonic hand piece/blade for determining the existence of unwanted vibration in the hand piece/blade. A tracking filter centered at the drive frequency of the generator, is used to monitor the drive frequency of the ultrasonic generator and attenuate the drive signal when it exceeds a predetermined level. The tracking filter has a wide pass band. Alternatively, a tracking filter having a pass band which is divided into several regions is used to avoid other longitudinal resonances, such as a resonance at a second harmonic, or other spectral features that would otherwise detract from the tracking accuracy of the filter.

Abstract: A method of characterizing the vibration of a plurality of rotating blades (12), such as turbine blades in a gas turbine engine, includes the steps of providing a single strain gauge (16A) on a single one (12A) of the blades and providing either one or two tip timing probes (22A, 22B) on a casing surrounding the blades. The data from the strain gauge (16A) allows the vibration of the single blade (12A) to be fully characterized while the data from the tip timing probes (22A, 22B) allows the amplitudes or velocities of vibration of all the blades to be determined. The relationship between the data from the tip timing probes for the single blade (12A) and the stress data from the strain gauge may be established. This relationship may then be assumed to apply to all the blades, thus allowing the stresses induced in all the blades by the vibrations to be determined.

Abstract: The invention relates to a process for analysis of roller bearings (15) which have been installed in machines, by means of a sensor (10) a signal being recorded which is produced by the rolling motion, and the signal amplitude is evaluated in order to determine the presence and optionally the depth of the damage in the roller bearing running surface (56). In doing so a dynamic model of the roller bearing in the machine is considered, in which at least the bilateral contact stiffnesses (4, 6) of the rolling elements are considered in order to determine the transfer function between the force caused by the damage and the corresponding sensor signal which is then taken into account in the signal amplitude evaluation. The invention furthermore relates to a corresponding analysis device.

Abstract: A method of verifying spindle bearing functionality prior to service, comprising: assembling a machine-tool spindle having an outer housing rotatably supporting an inner spindle shaft about a spindle axis by use of roller bearing sets, at least one set being compressed along the spindle axis to promote a resilient bearing preload force between the housing and shaft; suspending the housing of said assembly on a non-resonating flexible support, the spindle shaft being essentially isolated from the housing except for the preloaded rolling bearing set; sharply striking the inner spindle shaft along said spindle axis to induce an axially oscillating frequency; measuring the oscillating frequency in the shaft as it is affected by the degree of bearing preload of such at least one bearing set; and comparing the measured induced frequency to a known frequency analysis for the type of spindle assembly which is correlated to varying bearing preloads, the comparison indicating the spindle bearing functionality prior to

Abstract: An automated method for modeling spectral data is provided, wherein the spectral data generated by one of diffuse reflectance, clear transmission, or diffuse transmission. The method includes accessing a set of spectral data, the set of spectral data including, corresponding spectral data for each of a plurality of samples, the spectral data for each of the plurality of samples having associated therewith at least one constituent value, the at least one constituent value being a reference value for a target substance in the sample which is measured by a independent measurement technique. A plurality of data transforms are applied to the set of spectral data to generate, for each sample, a set of transformed and untransformed spectral data.

Abstract: A method and system for monitoring the condition of a bearing mounted on a rotating shaft, particularly one present in an aircraft gas turbine engine, where the vibration sensor that monitors the bearing is remote therefrom but proximate to the rotating shaft. The vibration sensor obtains a broadband signal having frequencies that include the bearing defect peak of the monitored bearing. The broadband signal is analyzed to identify the presence of the bearing defect peak. If the bearing defect peak is present, the amplitude of this peak is quantified to determine whether degradation of the monitored bearing has at least reached a threshold criteria previously established.

Abstract: An ultrasonic RFI source locator implements signal analysis to discriminate ultrasonic shocks emanating from power line equipment sources from ambient and other interference sources, as well as distinguish between specific type interference sources, such as corona and sparking discharge. The locator has a directional or contact ultrasonic sensor for receiving a signal representing the ultrasonic shocks from a targeted source, and includes signal processing circuitry to detect and compare the strengths of portions of the sensed signal that are modulated at whole integer multiples (harmonics) of an electrical power frequency (e.g., at 60 Hz and 120 Hz on a 60 Hz A/C power system, or 50 Hz and 100 Hz on a 50 Hz A/C power system) with each other, with the total signal and with selected non harmonic frequencies. The locator provides an operator indication of the result of this spectral analysis.

Abstract: The small tester is hand held by the writing pen body (21) when testing vibration with a housing mounted vibration probe (15) mechanically driving a piezo element (12), acted on by weight (11). The piezo element (12) has electrical connection (13) through an electronic circuit to an electronic display (22) indicating predetermined levels of vibration amplitude. The multi-level LED display (22) consists of four different coloured LED's where illumination of a specific coloured LED indicates a specific predetermined level of vibration amplitude. The electronic display (22) changing illumination of specific LED's from the lowest indicated level of vibration to just reach the highest indicated level of vibration is a nominal 6dB increase in vibration amplitude at predetermined frequencies.

Abstract: An apparatus for monitoring the health of a compressor comprising at least one sensor operatively coupled to the compressor for monitoring at least one compressor parameter, a calibration system coupled to the at least one sensor, the calibration system performing time-series analysis on the monitored parameter, a processor system for processing and computing stall precursors from the time-series analyzed data, a comparator that compares the stall precursors with predetermined baseline data, and a controller operatively coupled to the comparator which initiates corrective actions to prevent a compressor surge and stall if the stall precursors deviate from the baseline data which represents predetermined level of compressor operability. The processor system preferably includes a frequency demodulator and a system for processing the frequency demodulated signals to extract stall precursor characteristics.

Abstract: The behavior of the bogie of a muliple-axle vehicle is monitored. Accelerations of at least two axles of the bogie are measured with acceleration sensors allocated to the axles. The sensor signals are subjected to a Fourier transformation in FFT units. The frequency profiles resulting from the Fourier transform are compared with profiles that are stored in memory. Differences that are detected are compared with threshold values and messages are correspondingly sent to the system that controls the vehicle. The monitoring system allows mechanical operating errors of the bogie to be detected independently of effects caused by the running surface upon which the vehicle travels.

Abstract: A method is disclosed for evaluating the physical properties of a sample, for example, the grain size in a polycrystalline material. An ultrasound field is generated in a local region of the sample with a non-contact source, such as a pulsed laser, such that the generated ultrasound diffuses away from said local region. After waiting until the generated ultrasound field has reached a diffusion regime, the resulting ultrasound field is measured with a non-contact detector. Parameters are adjusted in a mathematical model describing the predicted behaviour of the ultrasound field in the diffusion regime to fit the detected ultrasound field to the mathematical model. In this way, parameters dependent on the physical properties of the sample, such as the diffusion coefficient and absorption coefficient, can be derived. The grain size, for example, can be estimated from these parameters preferably by calibrating the diffusion coefficient to grain size.

Abstract: A diagnostic system for a valve (2) that can be actuated by a position controller via a drive. The diagnostic system includes a device (14) provided for recording, storing, and evaluating, body sound spectra on the valve. In order to enable a valve to be diagnosed in a particularly reliable manner, a body sound spectrum which is recorded when the intact valve (2) is slightly open is stored in the device (14) provided for recording, storing, and evaluating, whereby the valve can be closed for diagnostic purposes and the resemblance of the recorded body sound spectrum to the stored body sound spectrum is used as a criterion for evaluating a non-sealing condition of the valve.

Abstract: Control method and control apparatus are capable of preventing vibrations of the feed system and thereby maintaining its optimum operating state for a long run. The control apparatus (1) includes an operation command generator (3) for generating an operation command signal according to an NC program, a position controller (4) for generating a speed command signal by multiplying a deviation between an operation command signal and a current position signal by a positional loop gain, a speed controller (5) for generating an electric-current command signal by multiplying a deviation between a speed command signal and a current speed signal by a speed loop gain, a filtering processor (6) for eliminating frequency components of a predetermined frequency band from the electric-current command signal, and adjusting processor (20) for adjustment of the elimination frequency band in response to the detected vibration level and vibrational frequency.

Abstract: The invention relates to a method for evaluating the condition of a machine (100) with a measuring point (90), which method is performed by a movable analysis apparatus (30). The method comprises the steps of producing a condition value, by means of measuring at the measuring point, which condition value is dependent on the actual condition of the machine, and storing the condition value in a writable information carrier (120) which is place by, or in the vicinity of, the measuring point (90) so that the condition value subsequently can be used as a reference condition value. The invention further relates to an apparatus for performing the method and a device for co-operating with the analysis apparatus and for mounting by a measuring point on machine (100).

Abstract: An apparatus for monitoring the health of a compressor comprising at least one sensor operatively coupled to the compressor for monitoring at least one compressor parameter, a calibration system coupled to the at least one sensor, the calibration system performing time-series analysis on the monitored parameter, a processor system for processing and computing stall precursors from the time-series analyzed data, a comparator that compares the stall precursors with predetermined baseline data, and a controller operatively coupled to the comparator which initiates corrective actions to prevent a compressor surge and stall if the stall precursors deviate from the baseline data which represents predetermined level of compressor operability. The processor system preferably includes a frequency demodulator and a system for processing the frequency demodulated signals to extract stall precursor characteristics.

Abstract: A method and apparatus for determining stress levels of membrane masks that may be used in membrane-based lithographic techniques is presented. A piezoelectric plate (30) is used to induce vibrations into the membrane mask (35), where the frequency and amplitude of the vibrations induced in the membrane layer (50) are optically sensed. By comparing the stimulus applied to the piezoelectric plate (30) with the response sensed optically in a gain phase analyzer (80), a frequency graph (110) associated with the membrane layer (50) is constructed such that resonant frequencies are easily determined. These resonant frequencies can then be used to calculate the stress associated with the membrane layer (50).

Abstract: Rolling stock equipment is disclosed that has a predictive diagnostic system to enable condition-based maintenance. The rolling stock equipment has vibration transducers on key equipment. Data from the transducers is periodically sampled. The data is analyzed to determine if a fault condition exists by comparing the vibration signatures to defined threshold levels. If a threshold level is exceeded, a fault warning is produced to alert maintenance staff that preventative maintenance should be performed.

Abstract: The geometry of a cavity in a cast, molded or machined part is compared to that of a reference part. Measuring the amplitude or phase shift of an acoustic wave traveling through the sealed cavity, at a multiplicity of predetermined frequencies, forms an acoustic spectrum, unique to the geometry of the cavity. The acoustic spectrum of the part under test is compared to the acoustic spectrum obtained from the corresponding cavity in a reference part.

Abstract: A method and system for determining material properties of a cross-section of an anisotropic sample material. An ultrasonic signal is applied to the surface of the anisotropic sample material, which comprises multiple constituent material layers, such that a characteristic medium wave is induced within each of the constituent materials. Each of these characteristic medium waves is sampled over a time interval to obtain a test waveform. This resultant test waveform is then spectrum analyzed utilizing cepstrum noise filtration, such that the material properties of said anisotropic sample material may be determined.

Abstract: Within the scope is a method for detecting the variator slip in continuously variable transmission (CVT transmission). The tribologic slip is detected by monitoring a rotating variator according to vibration and a subsequent evaluation.

Abstract: A high-speed bearing vibrational analysis system for testing a bearing includes a bearing holding member to accommodate a shaft and the bearing. The bearing holding member is adapted to rotate the bearing at high-speeds. The shaft is inserted into an accommodation portion of the bearing holding member. A vibration sensor is in contact with the bearing to detect vibrations of the bearing, while it is rotated at high speeds, and to transmit data for analysis. A computer system is provided for executing a software program that receives and analyzes the data from the vibration sensor.

Abstract: A method for determining the operational condition of a rotary machine is disclosed. The method comprises the steps of monitoring the machine under a baseline operating condition and collecting baseline vibrational data. A preselected number of baseline parameters are calculated from the baseline vibrational data. Next, a first baseline operational indicator is calculated from the baseline parameters, and the baseline parameters and the first baseline operational indicator are stored in a memory location. The machine is then monitored under a subsequent operating condition, and subsequent vibrational data is collected during the subsequent operating condition. A preselected number of subsequent operating parameters is calculated from the subsequent vibrational data, and a first subsequent operational indicator is calculated from the preselected number of subsequent operating parameters. Finally, the baseline data is compared to the subsequent operating data to determine the condition of the machine.

Abstract: A transmitter of audible sound waves is disposed at one end of a communicating hole of a cast molded article such as a cylinder block, and a receiver of audible sound waves is disposed at the other end of the communicating hole. The quality of the communicating hole is determined by receiving audible sound waves from a transmitter which have passed through the communicating hole and computing and processing a frequency spectrum of the received audible sound waves based on a reference frequency spectrum.

Abstract: An apparatus and associated method for detecting impending earthquakes includes at least one sensor, and preferably multiple sensors, for mounting on a building or other like structure, and include a transducer for converting vibration signals to electronic impulses. The signals are transmitted to a solid state detection circuit, which distinguishes between extraneous signals and signals indicative of the P-waves which signal an impending earthquake. Discrimination between relevant and non-relevant may be achieved by selecting a minimum amplitude and duration of signals within a selected frequency range, and triggering an alarm when the selected minimums are exceeded. Where multiple sensors are deployed, temporal overlap between selected signals can be assessed for further discrimination.

Abstract: An ultrasonic testing method and apparatus which includes synthesizing impulse response images using specially constructed waveforms. The apparatus includes a waveform generator, transducers for transmitting and receiving the ultrasonic signals and a digital signal processor or computer for efficiently processing the captured signal data to form the desired impulse response signals.

Abstract: Device and method for detecting anomaly of an air conditioner, the method including the steps of (1) detecting an acoustic emission signal from a compressor in the air conditioner during operation of the air conditioner, (2) detecting parameters of particular components from the detected acoustic emission signal, and (3) comparing the detected parameters to respective references, to determine anomaly of the air conditioner on the whole, whereby permitting the most reliable detection of anomaly of the air conditioner.

Abstract: A diagnostic system includes a vibration sensor mounted on a machine to measure vibrations. Vibration signals from the sensor are processed and analyzed by the system. From a known critical frequency of a vibration-generating component, the system measures the amplitude of the vibration signal at more than one harmonic frequency of the known critical frequency and compares the amplitudes to amplitudes at adjacent harmonic frequencies. When a relatively large amplitude is found at a harmonic frequency, that is a harmonic frequency near a resonant frequency of the physical path between the vibration sensor and the vibration-generating component, the system analyzes the shape and magnitude of the vibration signal around that harmonic frequency to evaluate the condition of the machine.

Abstract: A method for measuring the ripeness and the texture of a fruit, the method comprising a step for applying a vibration having sequentially hanging frequencies to a fruit to be measured, a step for measuring the intensity of the vibration applied to the fruit and the intensity of the vibration of the fruit, a step for measuring the weight of the fruit, a step for finding the transfer functional characteristic of the fruit by performing frequency analysis based on the intensity of the vibration applied to the fruit and the intensity of the vibration of the fruit, and computing the secondary resonance frequency f0 (i.e.

Abstract: A stencil generator for automatically constructing a stencil representative of signals having similar characteristics includes a boundary extractor and a component generator. The boundary extractor is operable to (i) receive a frequency spectrum of a signal, and (ii) obtain from the received frequency spectrum a plurality of characteristic frequency boundaries for the signal. The component generator is coupled to the boundary extractor and is operable to (i) receive the frequency spectrum, (ii) receive the plurality of characteristic frequency boundaries from the boundary extractor, and (iii) define a plurality of stencil components based upon the plurality of characteristic frequency boundaries and the frequency spectrum.

Abstract: A portable electronic vibration measurement device, detects a large number of structure-borne sound signals using a predetermined sequence of a plurality of specific individual measurements each plurality of measurements taken at a different sampling frequency.

Abstract: A vibration coupling stud for use in a vibration monitoring system includes digital memory and temperature sensing devices. Data is transferred between the vibration coupling stud and a vibration monitor. Data stored in the stud may include measuring point identification, prior measurement data, machine or bearing part numbers, and alarm limits.

Abstract: A route based ultrasonic monitoring method for use by an operator in detecting when the ultrasonic sound produced by a device indicates the presence of a leak or machinery defect. The route based ultrasonic monitoring method uses a central processing location to store testing information concerning which machines to test and how to configure a portable ultrasonic sensing device to test them. At the appropriate time, the testing information is loaded from the central processing location into the portable processing and storage unit. The operator is then prompted by the portable processing and storage unit to proceed to a test location. Once at the test location, the portable processing and storage unit provides the testing information to the portable ultrasonic sensing device. The test is then performed by the operator with the portable ultrasonic sensing device and the test results are downloaded from the portable sensing device to the portable processing and storage unit.

Abstract: Disturbances of a periodic nature, such as those occurring in a rotating device can be attenuated by a cancellation function. A cancellation signal is produced by extracting one or more frequency components (harmonics) from a disturbance. A set of weighting coefficients are generated by an artificial neural network based on information derived from the selected frequency components of the periodic disturbance signal. The artificial neural network algorithm adapts in real time to shifts in the magnitude and phase of the disturbance frequencies selected for attenuation at the sensor location. In turn, these coefficients are applied to a function of a similar number of components and applied to the rotating device. Over a period of time, feedback and adaptation will attenuate the disturbance at the selected frequencies.

Abstract: Non-synchronous vibrations in blades on a rotating wheel, such as a turbine wheel, are measured using Fourier analysis adjusted to correct for uneven sampling produced by a pair of probes spaced from each other about the wheel by a probe angle (PA) other than 180.degree.. The Fourier transform matrix is phase shifted by an amount which is a function of the PA which is other than 180.degree., and the harmonic in which the mode of non-synchronous vibration is expected to be found. A scaling factor in the form of an inverse correction factor is applied to the frequency spectra produced by the phase shifted Fourier transform matrix to generate an output representative of the frequency and amplitude of the true excitation frequency which can be presented on a display.

Abstract: A displacement detecting apparatus includes a scale having a graduation of predetermined pitches, a sensor which is displaceable with respect to the scale and detects a period signal corresponding to the pitch. Interpolating sections interpolate the periodic signal from the sensor by different resolutions. One of the interpolating sections outputs a first interpolation signal of m (positive integer) phases shifted by a phase difference .theta.1, and the other interpolating sections outputs a second interpolation signal of n (positive integer) phases shifted by a phase difference .theta.2.

Abstract: A spectrum analyzer measures a time difference between two or more signals with different carrier frequencies or a time delay between two or more signals with the same carrier frequency. The spectrum analyzer includes at least two measurement channels, each of the measurement channels has a frequency mixer, a local oscillator and an IF (intermediate frequency) filter for mixing an input signal to be measured with a local signal of the local oscillator to produce an IF signal which passes through the IF filter, and a demodulator provided in one of the measurement channels to demodulate the IF signal produced from the input signal to generate a trigger signal to start an operation of the other measurement channel.

Abstract: 051545044A method and apparatus for compressing, storing and transmitting measurement data correlative to machine status is disclosed in which the measurement data is continuously sensed, sampled and processed to extract significant spectral elements including magnitude and phase information from each successive period of the originally measured data and to store those spectral elements in a memory means from an initial period of significant spectral elements and each successive period of significant spectral elements which have changed since the previous period for developing a compressed data history correlative to a continuous history of the status of the machine being monitored and from which continuous signals can be regenerated and analyzed for any earlier historical time.

Abstract: A vibration coupling stud for use in a vibration monitoring system includes digital memory and temperature sensing devices. Data is transferred between the vibration coupling stud and a vibration monitor. Data stored in the stud may include measuring point identification, prior measurement data, machine or bearing part numbers, and alarm limits.

Abstract: An ultrasonic stroboscope is used to inspect an object rotating at a first frequency to determine if the rotating object has any defects. The ultrasonic stroboscope includes a first acoustic transducer spaced apart from the rotating object. The first transducer is configured to radiate ultrasonic energy at the rotating object at a second frequency. The second frequency is substantially related to a sub-harmonic of the first frequency so that the rotating object appears acoustically substantially still. A second acoustic transducer is used to sense a reflection of the ultrasonic energy from a defect in the rotating object. The second transducer translates the sensed reflection into at least one reflection signal. A user interface is coupled to the reflection signal.

Abstract: The disclosed invention senses a machine's vibration spectrum, converts the vibration signal into a frequency-domain vibration spectrum, and analyzes the vibration spectrum to generate a narrowband alarm limit envelope against which the vibration spectrum of a previously uncharacterized machine may be compared. The limit envelope is generated from the test vibration spectrum of the machine which is the subject of the test, thus providing a performance benchmark against which to compare the vibration level of the previously uncharacterized machine. A limit envelope is also generated from a test vibration spectrum which has been designated as a reference or baseline spectrum. Further, a limit envelope is generated based upon a mean spectrum which is generated by combining several test vibration spectra. A limit envelope is also generated based upon mean and standard deviation spectra when a statistically significant number of test spectra are available.

Abstract: An apparatus and method for determining the dynamic response of a physical structure is disclosed. A single sheet of a piezoelectric polymer film, preferably polyvinylidene fluoride, or PVDF, is coated on one side with a thin layer of conductive material to serve as a ground electrode. The other side of the sheet is coated with a thin layer or conductive material in a non-contiguous pattern of individual electrodes defining an array of discrete piezoelectric transducers. Sensor leads are connected to each individual electrode and lead to a signal processor which includes associated software for determining from the processed electrical signals relative strain amplitudes of the surface area of a physical structure onto which the sheet is attached. The resulting output can be used to record strain time histories for later processing or, more simply, to show the time-averaged, steady state strain response of a structure.

Abstract: An apparatus for determining a road pavement surface condition over a wide area has a road noise sensor (12). A temporal frequency analyzer (18) converts a road noise signal from the road noise sensor (12) to a temporal frequency signal. A processing circuit (20) receives the temporal frequency signal from the temporal frequency analyzer (18) and analyzes the temporal frequency signal to determine the road pavement surface condition.