Abstract: The present invention relates to a method and apparatus of determining the rheological properties of a polymer flowing in a conduit. The invention provides a method of characterising a polymer under test, comprising: Detecting acoustic emissions from said polymer flowing in a conduit to provide acoustic emission data, comparing the acoustic emissions data obtained against acoustic emission data from a polymer, or a series of polymers, of known characteristics, and thereby characterising the polymer.

Abstract: Apparatus and method of measuring acoustic properties of a drumhead of a drum are disclosed. The acoustic properties are measured by exciting the drumhead with a source of energy and detecting the acoustic energy emitted by the drumhead. The acoustic energy emitted by the drumhead may be measured using a microphone or other acoustic sensor. The use of multiple energy sources provides isolation of acoustic energy and allows measurement of local resonance of the drumhead.

Abstract: A device and system are provided for monitoring acoustic emissions from machinery to indicate levels of detected sound waves. Each incorporates an acoustic sensing device which incorporates a housing assembly constructed for removable attachment between a surface mounting region of the machinery and a measuring instrument to define a coupled state. An acoustic emissions sensor is disposed in the housing assembly's interior to detect sound waves propagating through the surface mounting region and to produce detection signals for processing by the measuring instrument. A methodology for monitoring acoustic emissions is also provided.

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 vibration sensor mounted on a tree on the earth outputs a signal voltage corresponding to a sound from the earth. The signal voltage is continuously measured by a sound observing device and read into a data processing device. The data processing device has a forecasting unit which performs a long-term weather forecasting process based on the value of the signal voltage, i.e., a sound pressure level representing the magnitude of the sound pressure of the sound from the earth. Specifically, the forecasting unit forecasts long-term weather conditions such as warm and cold climates related to high and low temperatures three and six months after the measurement of the sound from the earth, based on changes in the sound pressure level of the measured sound.

Abstract: A system and method for testing at least one joint in a linkage includes a platform system, a torque system, an articulation assembly and a fault detection system. The platform system receives a first shaft connected to a first joint in the linkage and the torque system applies torque to the first joint without substantially rotating the first shaft or joint, a second shaft connected to a second joint in the linkage or the second joint. The articulation assembly receives the second shaft and moves the second joint in a substantially circular path without substantially rotating the first shaft or joint and the second shaft or joint. The fault detection system determines the condition of the linkage based upon detected signals emitted from the linkage while the first joint is torqued and the second joint is moved.

Abstract: Acoustic emission apparatus methods for detecting termite infestation including a probe and signal processing circuitry. The probe includes an piezoelectric transducer and is adapted to be inserted into a bore-hole of the wood under test. The waveguide intersects the high frequency extensional and shear waves produced by feeding and movement of termite propagating along the grain of the wood. The transducer output signal is filtered through high (HF) and low (LF) bandbase filters. Selected HF/LF values produce a signal which substantially eliminates extraneous Out-Of-Plane acoustic noise. One embodiment includes a multiple channel multiplexing system for monitoring insect treatment processes in structures such as homes and other buildings. The real time data is used to determine the effectiveness of treatments as well as the time required to produce an effective treatment for termite eradication.

Abstract: The invention encompasses an electrical apparatus. Such apparatus includes RFID circuitry on a first substrate, and sensor circuitry on a second substrate. A receiving structure is associated with one of the RFID circuitry and the sensor circuitry, and at least one connecting structure is associated with the other of the RFID circuitry and the sensor circuitry. The at least one connecting structure is removable received within the receiving structure. The invention also encompasses a method of forming an electrical apparatus. A first substrate and a second substrate are provided. The first substrate has RFID circuitry thereon, and the second substrate has sensing circuitry thereon. A receptacle is joined with one of the RFID circuitry and the sensor circuitry, and has at least one orifice extending therein. At least one prong is joined with the other of the RFID circuitry and the sensor circuitry.

Abstract: A method and system for analyzing hydraulic turbine noise vibrations involves recording the noise of a hydraulic turbine either during operation or intentionally produced for testing from a remote site. A standard laptop computer is utilized by personnel at the turbine site to record the sound at different power outputs as specified by turbine experts with a standard Windows sound recording program that produce sound files. The sound files are compressed at the site and sent to the expert office location via Email. Once received at the expert location, the sound files are uncompressed and analyzed immediately by the turbine experts without the experts having had to travel to the remote site. The analysis is done with a software sound analyzer. The analyzed signals are used to diagnose the machine and address any unusual recorded noise.

Abstract: One embodiment of the present invention relates to an acoustic property analysis device that does not require the predetermination of the fast and slow axis of the material. The device generally includes at least two acoustic transducer elements that are positioned on a sample in a specific orientation relative to one another. The acoustic transducer elements are independently coupled to waveform generators. The independent waveform generators can generate particular waves in each of the acoustic transducer elements to produce a resulting wave having a known polarization. The resulting wave propagates through the sample and is affected by the particular anisotropic properties of the sample. The components of the resulting wave are generally affected differently by the anisotropic properties in the sample. For example, one of the component waves may propagate faster than another wave through a particular defect in the sample.

Abstract: The invention relates to a method of controlling the integrity of hollow fibre filtration units and of detecting leaks through a wholly or partially ruptured fibre. The inventive method is characterised in that it consists in: —emitting a noise or audible signal using an emitter located on one side of the membranes of the filtration units; —detecting the noise or audible signal emerging from a ruptured fibre on the other side of the membranes, regardless of whether or not a fluid is passing through said fibre; —amplifying the signal-noise thus obtained; —and comparing the resulting amplified signal to a threshold noise level in the same frequency range.

Abstract: A nondestructive acoustic emission testing system using electromagnetic excitation, comprises: a) an electromagnetic wave generator for generating electromagnetic waves that stimulate a test sample to generate acoustic energy; b) an acoustic energy sensor for detecting the acoustic energy and generating a first output signal that represents the acoustic energy; and c) a data processor for comparing the output signal with a reference and for generating a second output signal that represents a characteristic of the test sample.

Abstract: A method is used for checking the air noise of a motor vehicle, particularly of a passenger car, which air noise is generated by air flowing onto an outer skin of a vehicle body of the passenger car. In order to optimize this method, targeted air currents are applied by means of a blower to a stationary passenger car in areas where sealing devices extend between stationary vehicle body structures and movable vehicle body elements of the vehicle body, and the air noise occurring as a result of the air currents is measured subjectively and/or objectively. For the implementation of the method, a device is used in the case of which the blower comprising the outflow cross-section is a component of a flow device which is equipped with a blast nozzle for acting upon measuring points on the outer skin.

Abstract: A passive SAW strain sensor for remotely sensing strain within a surface has a receiving SAW correlator with a signal input interdigitated transducer and a plurality of adjacent successive spaced interdigitated output transducers on a piezoelectric substrate, and a transmitting SAW correlator having a plurality of adjacent successive spaced interdigitated output transducers and a signal output interdigitated transducer on a piezoelectric substrate. The transmitting SAW correlator is affixed to or embedded in the surface such that its substrate will be stressed when the surface is strained and the receiving SAW correlator is not affixed to or embedded in the surface. The output transducers of the receiving SAW correlator and the transmitting SAW correlator are spatially placed to define a unique frequency of sensitivity, and their outputs are coupled together.

Abstract: The present invention is for a system (11) or method for conditioned based monitoring of a bearing assembly. The system (11) comprises a sensor (13) placed in proximity to a bearing assembly (12). The sensor (13) generates a signal indicative of the amplitude and frequency of the vibrational movement of the bearing assembly. A process (14) in communication with the sensor (13) receives the signal from the sensor (13) and generates spectral data representative of the bearing vibrational movement. A database (15) comprises data representative of an amplitude threshold, for at least one predetermined frequency, characteristic of a bearing fault. The processor (15) compares the spectral data to the amplitude threshold and generates a signal indication of the bearing assembly.

Abstract: A system for detecting a sound level of vehicles comprising sensor units for detecting vehicles on a road and for measuring a sound level of a detected vehicle. A data processing unit is connected to the sensor units and has an identification recorder for operating the system by recording an identification of the vehicle detected if the sound level is above a given value.

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: Described herein is a technology for facilitating diagnosis of the operation of devices or machines based, at least in part, upon the acoustics of such.

Abstract: A palm-held acoustical sensing device provides improved accessibility within an engine compartment for sensing engine noise in order to perform diagnostics. Miniaturized electronics are provided within a compact housing that permits free use of the sensing device within an engine compartment, enabling access to engine components that have previously been accessible only with great difficulty. Clamping sensors having wider bandwidth than existing clamping sensors provide improved sensing capability and an electronics and battery housing having one or more sensor input jacks provides for attachment of multiple sensors, improved storage and a lower cost unit providing the advantages of both a flexible shaft sensing unit and a clamping unit.

Abstract: Methods and apparatus for atmospheric sounding using acoustic chirps are disclosed, the transmitted and echo chirps being compared in a mixer that yields frequency sums and differences. Preferably, the mixing is performed as a complex multiplication in the Fourier domain. In one system (1) a signal generator (5) such as a PC sound card drives a loudspeaker (3) that serves as a transmitter and echo pulses are detedcted by a microphone (4) that serves as a receiver. Chirps transmitted by the loudspeaker (3) travel by different paths (7a and 7b) due to reflection from TILS or thermal inversion layers (2a and 2b) at different altitudes. The transmitted and echo chirp signals are compared in a mixer (6) from which various outputs (8 and 9) can be generated. One output (8) might be the magnitude of the difference between the transmitted and echo chirp tones, instant by instant, which is indicative of the altitudes of the respective TILs.

Abstract: Acoustic emission apparatus methods for detecting termite infestation including a probe and signal processing circuitry. The probe includes an piezoelectric transducer and is adapted to be inserted into a bore-hole of the wood under test. The waveguide intersects the high frequency extensional and shear waves produced by feeding and movement of termite propagating along the grain of the wood.

Abstract: A friction force measurement apparatus which measure friction force between a fixed member fixed on a main body of a magnetic tape drive and a magnetic tape abrading the fixed member is characterized by being equipped with a vibration detector which is joined with the fixed member and a vicinity of the fixed member and detects vibration in abrasion of the magnetic tape with the fixed member, and a calculation device which calculates the friction force between the fixed member and the magnetic tape based on a signal from the vibration detector.

Abstract: A vibration testing device includes a computer system having: a measurement processing block for inputting an output of the monitoring sensor and processing the output; a model substituting block for modeling characteristics of the test piece, calculating a response quantity corresponding to a drive condition of an actuator, and inputting the calculation result to a numerical simulation block and the parameter changing block; the parameter changing block for comparing the calculation result of the model substituting block with the processing result of the measurement processing block, and changing the parameter; the numerical simulation block for calculating a vibration response in accordance with a previously input structure numerical model; and a waveform generating block for calculating a time function of a deformation to be applied to the test piece, and outputting the time block to the actuator controlling device.

Abstract: The present invention relates to a method and apparatus of determining the rheological properties of a polymer flowing in a conduit. The invention provides a method of characterising a polymer under test, comprising: Detecting acoustic emissions from said polymer flowing in a conduit to provide acoustic emission data, comparing the acoustic emissions data obtained against acoustic emission data from a polymer, or a series of polymers, of known characteristics, and thereby characteristing the polymer.

Abstract: Apparatus for non-destructively testing material to enable detection of any damage sites, comprising means for generating localised heating at any damage site in the material, and means for imaging the material to enable detection of any localised heating at the damage site.

Abstract: A device and system are provided for monitoring acoustic emissions from machinery to indicate levels of detected sound waves. Each incorporates an acoustic sensing device which broadly comprises a housing assembly constructed for removable attachment between a surface mounting region of the machinery and a measuring instrument to define a coupled state. An acoustic emissions sensor is disposed in the housing assembly's interior to detect sound waves propagating through the surface mounting region and to produce detection signals for processing by the measuring instrument. A methodology for monitoring acoustic emissions is also provided.

Abstract: Brittleness of a coating substance such as a coating film that is too brittle and/or too thin to be independently removed or handled is rated on the basis of an outcome of detection of acoustic emissions which are produced when a test film piece prepared by laminating a support with the coating substance is deformed by a compression transverse test device and detected by an AE sensor attached to the test film.

Abstract: An acoustic monitoring method and system in laser-induced optical breakdown (LIOB) provides information which characterize material which is broken down, microbubbles in the material, and/or the microenvironment of the microbubbles. In one embodiment of the invention, femtosecond laser pulses are focused just inside the surface of a volume of aqueous solution which may include dendrimer nanocomposite (DNC) particles. A tightly focused, high frequency, single-element ultrasonic transducer is positioned such that its focus coincides axially and laterally with this laser focus. When optical breakdown occurs, a microbubble forms and a shock or pressure wave is emitted (i.e., acoustic emission). In addition to this acoustic signal, the microbubble may be actively probed with pulse-echo measurements from the same transducer. After the microbubble forms, received pulse-echo signals have an extra pulse, describing the microbubble location and providing a measure of axial microbubble size.

Abstract: A network for detecting a substance includes at least two detectors that are capable of transmitting a signal, and a remote station capable of receiving the signal. The detectors are adapted to detect a substance and transmit data that indicates the presence of that substance to the remote receiving station.

Abstract: The invention provides an acoustic diagnosis/measurement apparatus/method using a pulse of electromagnetic force, capable of non-destructively and precisely diagnosing or measuring corrosion, adhesion, the. cover depth, and/or the diameter of a reinforcing iron rod in a structure made of reinforced concrete. A coil 12 is attached to a surface of a structure 11 including a conductor 11a and a non-conductive material 11b covering the conductor 11a. A current pulse is applied to the coil 12 thereby generating a magnetic field pulse. The magnetic field pulse causes an eddy current to be induced in the conductor 11a. The conductor 11a is oscillated by interaction between the eddy current and the magnetic field pulse. As a result, an acoustic signal is generated by the conductor 11a and the acoustic signal is converted into an eclectic signal by an acoustic transducer 14 disposed to the surface of the structure 11.

Abstract: A method for detecting an obstruction in a flow duct is provided. The method includes the steps of directing gas through at least one port of the flow duct, measuring a flow noise level of the gas directed through the at least one port, and comparing the noise level with a predetermined noise level. In the event that the flow noise level exceeds the predetermined noise level by at least a threshold amount, then the method includes the step of indicating the presence of an obstruction in the at least one port.

Abstract: An apparatus and method for monitoring and reporting downhole bit failure. Sensors are located on a sub assembly (which is separate from the drill bit itself but located above it on the drill string). Data from the sensors (preferably accelerometers) are collected in blocks, then analyzed in the frequency domain. The frequency domain is divided into multiple bands, and the signal power in each band is compared to that of another band to produce a ratio of powers. When a bit is operating at normal condition, most of the spectral energy of the bit vibration is found in the lowest frequency band. As a bearing starts to fail, it produces a greater level of vibration in the higher frequency bands. This change in ratios is used to determine probable bit failure. Bit failure can be indicated by a given ratio surpassing a given threshold, or by monitoring the standard deviation of the frequency ratios. When the standard deviation exceeds a certain value, a failure is indicated.

Abstract: A sensor for detecting stress waves for use in a stress wave analysis system. The stress waves are preferably detected in a narrow frequency range of 35-40 KHz. At this range, stress waves from friction and impact sources typically propagate through machine structures at detectable amplitudes. In order to maximize the signal to noise ratio of stress waves, relative to background noise and vibration, the sensor of the present invention is designed and calibrated with a frequency response and damping features that are specifically tailored for stress wave analysis. The sensor is a multi-functional sensor that can measure a number of logically related parameters for indicting the mechanical condition of a machine. It is often desirable to measure both friction and one or more other parameters appropriate for indication of a machine's health, where all of the measuring capability is contained in one sensor.

Abstract: In order to create a method for checking workpieces with at least one interior space, which is easy and quick to carry out, it is proposed that the method comprises the following steps:

Abstract: Formed Laser Sources (FLS) using pulsed laser light for generation of ultrasonic stress waves are combined with air-coupled detection of ultrasound to provide for the hybrid non-contact, dynamic and remote ultrasonic testing of structural materials, especially railroad tracks. Using this hybrid technique, multimode and controlled frequency and wavefront surface acoustic waves, plate waves, guided waves, and bulk waves are generated to propagate on and within the rail tracks. The non-contact, remote nature of this methodology enables high-speed, full access inspections of rail tracks. The flexibility and remote nature of this methodology makes possible the detection of critical cracks that are not easy, or impossible to detect, with current inspection techniques available to the railroad industry. For purpose of field testing, the equipment of the present invention can be located above the top surface of the rail.

Abstract: A vibration sensor mounted on a tree on the earth outputs a signal voltage corresponding to a sound from the earth. The signal voltage is continuously measured by a sound observing device and read into a data processing device. The data processing device has a forecasting unit which performs a long-term weather forecasting process based on the value of the signal voltage, i.e., a sound pressure level representing the magnitude of the sound pressure of the sound from the earth. Specifically, the forecasting unit forecasts long-term weather conditions such as warm and cold climates related to high and low temperatures three and six months after the measurement of the sound from the earth, based on changes in the sound pressure level of the measured sound.

Abstract: Method for measuring friction in a hair sample, comprising: (a) providing a friction member; (b) drawing it through the hair, generating a frictional noise signal; and (c) capturing the signal by a noise sensor. Device suitable for use in said method, comprising comb means having a plurality of tines and a noise sensor arranged to capture frictional noise generated by passage of comb means through the hair. System for assessing the level of damage in a hair sample, comprising: (a) defining hair categories; (b) associating with each category a standard trace representative of the frictional noise signal generated when a standard sample in that category is subjected to said method; (c) assigning the sample to one of the categories; (d) carrying out said method on the sample; (e) visually displaying the frictional noise signal generated as a trace; (f) and comparing the sample's trace with the standard trace associated with the category.

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: A diagnostic apparatus and method for sensing a signal emanating from a machine and determining a periodic machine event based on the emanated signal. The apparatus includes analog to digital processing components for digitizing the sensed signal, producing a digitized signal. The apparatus also includes a transform algorithm, memory, an analysis algorithm, and a display. The transform algorithm transforms the digitized signal to generate power spectral density and autocorrelation data which is stored in the memory. The analysis algorithm includes criteria for analyzing the stored power spectral density and autocorrelation data to determine a period machine event based at least in part upon the autocorrelation data. The display displays the periodic machine event to a user. In the event of a suspected defect or fault, the device alerts the user. The user may then elect to proceed with repairs or undertake advanced analysis of the suspected fault as economy dictates.

Abstract: An ultrasonic transducer (108) for use in medical imaging comprises a substrate (300) having first and second surfaces. The substrate (300) includes an aperture (301) extending from the first surface to the second surface. Electronic circuitry (302) is located on the first surface. A diaphragm (304) is positioned at least partially within the aperture (301) and in electrical communication with the electronic circuitry (302). The diaphragm (304) has an arcuate shape, formed by applying a differential pressure, that is a section of a sphere. A binder material (314) is in physical communication with the diaphragm (304) and the substrate (300).

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: A flexible piezoelectric-based transducer, mounted on a circumference of a rotating object senses acoustical energy traversing portions of the object. In a preferred embodiment, the transducer is affixed, using a suitable adhesive, within the enclosed portion of a wheel/tire assembly. The transducer senses acoustical energy, e.g., ultrasonic transmissions, generated by the tire contacting the road surface at its contact patch and, without need of external power, translates it to an electrical current and communicates it for further processing. Because the acoustical impedance of the tire casing changes with temperature, hot spots within the tire, as well as other characteristics of the tire's operation, can be detected. Further, any Doppler shift which occurs due to the rotating medium may be compensated for since the rate of tire rotation may be made known via a speed sensor. A position sensor may also be employed to indicate the position of the hot spot.

Abstract: The invention encompasses an electrical apparatus. Such apparatus comprises a first substrate having first circuitry supported thereby. The first circuitry defines at least a portion of a radio frequency identification device. At least one first electrical node is supported by the substrate and in electrical connection with the first circuitry. The apparatus further comprises an input device comprising a second substrate and second circuitry on the second substrate. The second circuitry is in electrical communication with at least one second electrical node. Neither of the first nor second electrical nodes is a lead, and the second electrical node is adhered to the first electrical node to electrically connect the input device with the radio frequency identification device. The invention also encompasses a termite-sensing apparatus. Additionally, the invention encompasses methods of forming electrical apparatuses, and methods for sensing termites.

Abstract: A method for detecting an obstruction in a flow duct is provided. The method includes the steps of directing gas through at least one port of the flow duct, measuring a flow noise level of the gas directed through the at least one port, and comparing the noise level with a predetermined noise level. In the event that the flow noise level exceeds the predetermined noise level by at least a threshold amount, then the method includes the step of indicating the presence of an obstruction in the at least one port.

Abstract: An acoustic monitoring device has at least two acoustic sensors with a triggering mechanism and a multiplexing circuit. After the occurrence of a triggering event at a sensor, the multiplexing circuit allows a recording component to record acoustic emissions at adjacent sensors. The acoustic monitoring device is attached to a solid medium to detect the occurrence of damage.

Abstract: Internal combustion engines and electric motors in motor vehicles generate, at all operating points, airborne emissions and solid-borne emissions, which are superimposed in the interior of the vehicle and perceived as engine noise by the occupants. To differentiate quantitatively between airborne and solid-borne portions of engine noise, sound measurement are made in the vehicle interior and engine compartment both with air and when the engine compartment is flooded with a gas having different acoustic characteristics than air. From analysis of the two measurements, the solid-borne portion and the airborne portion of the engine noise can be determined with a high degree of precision.

Abstract: A system for monitoring the flow of a fluid such as water in a pipe, including a remote pressure sensor operably connected to the pipe for sensing the pressure of the fluid at the location of the pressure sensor. An acoustic transmitter is placed proximate the remote pressure sensor for transmitting the output of the sensors by an acoustic signal transmitted through the fluid in the pipe to an acoustic receiver that generates a control signal in response thereto control a pressure control valve for adjusting the pressure in the pipe in response. The system is intended for a water distribution networks that include a plurality of pipes, with a remote pressure sensor, transmitter, receiver and control device for at least some of the plurality of pipes.

Abstract: Thermoplastic welding is an emerging technology targeted at significantly reducing the manufacturing cost of aerospace structure by eliminating fasteners and the touch labor associated with fasteners to prepare, install, and inspect the assemblies. Quality welds are highly dependent upon achieving appropriate temperatures everywhere along the bond line. The present invention is a system that evaluates the quality of the welds involving inputting an EM pulse to the embedded susceptor and listening to the acoustic response that the pulse generates to determine weld quality from the sound.

Abstract: A crack detection method and system capable of detecting cracks on a scale of about 5 &mgr;m or greater, useful for detecting cracks in sol-gel tubes. An electromagnetic radiation signal is transmitted from a sensor to a body in which cracking may occur. The signal is reflected back to and received by the sensor. An output voltage from the sensor is measured which is proportional to a signal characteristic change between the transmitted and received signals. Signal characteristics such as frequency, phase, and amplitude may be monitored. The signal characteristic change may result from one or more mechanisms selected from the group consisting of microscopic motion of the body, media transition and fluid movement.

Abstract: There is disclosed a system for detecting defects in wheels, tires, bearing and supporting mechanisms of a vehicle. A plurality of microphones is installed in different locations of the vehicle to receive noises or sounds when the vehicle is in motion. The electrical signals converted from the noises or sounds by each microphone are fed to an amplifier and filter circuit. The amplified signals are fed to a loudspeaker located preferably in the compartment of the driver. By sequentially monitoring the levels of the amplified and filtered signals from each microphone or in a pair of microphones, defects in the wheels, tires and bearings can be detected before the occurrence of further damages or accidents. The levels of the amplified signals from each microphone may be displayed simultaneously by an array of light emitting devices.