228results about "Fluid pressure measurement by acoustic means" patented technology

A sensor head characterizes unsteady pressures in a fluid flowing within a pipe, as may be caused by one or both of acoustic waves propagating through the fluid within the pipe and/or pressure disturbances that convect with the fluid flowing in the pipe. The sensor head comprises a rigid support structure and at least one transducer attached to the rigid support structure. The rigid support structure holds the transducer in contact with an outer surface of the pipe. The at least one transducer senses relative movement between the outer surface of the pipe and the support structure and provides a signal indicative of unsteady pressures within the fluid at a corresponding axial position of the pipe in response to the relative movement. The support structure may be attached to each transducer in an array of transducers, and may include a handle secured thereto for manipulating the sensor head into contact with the pipe. Output signals from the transducers are provided to a processing unit, which processes the output signals to provide a signal indicative of at least one parameter of the flow process.

An apparatus and methods for acoustically analyzing a fluid sample and determining one or more properties of the sample are disclosed by the present invention. The apparatus comprises a chamber, a transmitter positioned within the chamber for transmitting an acoustic signal through the fluid, a reflector movably positioned within the fluid inside the chamber for reflecting the acoustic signal, and a receiver positioned within the chamber for detecting reflections of the acoustic signal. The methods employ the use of a transmitter, a reflector movably positioned within the fluid inside the chamber, and a receiver to characterize the fluid sample based on one or more of its acoustic properties.

Disclosed is a pressure measuring system for a vacuum chamber, in particular, a pressure measuring system for a vacuum chamber using ultrasonic wave. In this regard, there is provided a pressure measuring system for a vacuum chamber using ultrasonic wave, comprising a vacuum chamber 10 formed with desired vacuum at the inside thereof; ultrasonic wave-emitting means mounted close to an outer peripheral surface of the vacuum chamber 10 for emitting an ultrasonic wave 62 to the inside of the vacuum chamber 10; ultrasonic wave-receiving means for receiving a reflection wave 64 reflected after the striking of the ultrasonic wave 62 emitted from the ultrasonic wave-emitting means to the vacuum chamber; reflection wave-detecting means for detecting the reflection wave 64 from the ultrasonic wave-receiving means; and amplitude-analyzing means for analyzing the amplitude of the reflection wave 64 detected by the reflection wave-detecting means.

A perceptual weighting device for producing a perceptually weighted signal in response to a wideband signal comprises a signal pre-emphasis filter, a synthesis filter calculator, and a perceptual weighting filter. The signal pre-emphasis filter enhances the high frequency content of the wideband signal to thereby produce a pre-emphasized signal. The signal pre-emphasis filter has a transfer function of the form: P(z)=1−μz⁻¹, wherein μ is a pre-emphasis factor having a value located between 0 and 1. The synthesis filter calculator is responsive to the pre-emphasized signal for producing synthesis filter coefficients. Finally, the perceptual weighting filter processes the pre-emphasized signal in relation to the synthesis filter coefficients to produce the perceptually weighted signal. The perceptual weighting filter has a transfer function, with fixed denominator, of the form: W(z)=A(z/γ₁)/(1−γ₂z⁻¹) where 0<γ₂<γ₁≦1.

The invention discloses a structure of two resonant micro pressure sensor chips and a method of manufacturing the same. The structure of two resonant micro pressure sensor chips comprises a pressure inductive diaphragm with one or two rigid cores, a double-end clamped support beam and a cover plate 3. Under the function of fluid pressure, the diaphragm with rigid cores deforms to exert the double-end clamped support beams on the surface of the diaphragm to change resonant frequency upon the function of axial stress. Fluid pressure can be reflected by measuring the change in the resonant frequency of the double-end clamped support beam. The silicon resonant micro pressure sensor of the invention has higher signal-to-noise ratio, resolution, sensitivity and measurement precision and the output of the invention is the frequency signal.

A pressure sensor includes: a supporting body which has an opening; a pressure detecting portion which includes a supporting film provided on the supporting body and having a diaphragm portion closing the opening, and a piezoelectric body provided on the diaphragm portion and deflecting to output an electric signal; a frame body which has, on the pressure detecting portion, a cylindrical cavity along a film thickness direction of the supporting film, and is formed, in plan view when viewed from the film thickness direction of the supporting film, at a position where a cylindrical inner peripheral wall of the cavity overlaps with the opening, or outside of the opening; a sealing film which closes the frame body; and a silicone oil which is filled in an inner space formed of the cylindrical inner peripheral wall of the cavity, the sealing film, and the pressure detecting portion.

A pressure sensor (52) for a harsh environment such as the combustion chamber (58) of a gas turbine engine (50). The pressure sensor includes an acoustic waveguide (60) having a sensing portion (66) exposed to the combustion gas in the combustion chamber. Modulations in an acoustic signal passing through the acoustic waveguide are sensed and correlated to pressure fluctuations in the combustion gas. The sensing portion of the waveguide includes a core acoustic waveguide element (42) covered by a coating material (44). The coating material not only protects the core from the harsh environment, but it also improves the efficiency of the transfer of energy from the combustion gas into the waveguide because it provides a stepped transition from the acoustic impedance of the gas to the acoustic impedance of the core material. The protective coating may have a plurality of layers (46, 48) and/or it may include a graded material (78, 80) having an acoustic impedance value that varies across its depth.

The invention provides a signal processor that receives a signal containing information about an acoustic signal that is generated by at least one acoustic transmitter, that travels through an aerated fluid in a container, and that is received by at least one acoustic receiver arranged in relation to the container, including inside the container; and determines the gas volume fraction of the aerated fluid based at least partly on the speed of sound measurement of the acoustic signal that travels through the aerated fluid in the container. The signal processor also sends an output signal containing information about the gas volume fraction of the aerated fluid. The signal processor may be configured together with at least one acoustic transmitter, the at least one acoustic receiver, or both.

A conduit (106), with geometry designed to enhance pressure sensitivity, is vibrated at resonance in two modes along different cross-sectional axes (a, b). Measuring the change in the frequency ratio squared of the modes yields a substantially linear relationship to pressure that is substantially immune to other material properties and other environmental factors. Moments of inertia in different cross-sectional axes are related to pressure as a result of the elliptical or oral cross section of the conduit (106).

The invention belongs to the technical field of ultrasonic cavitation detection and signal analysis, and relates to a method and a device for separating and detecting focused ultrasonic cavitation signals. An ultrasonic transducer of a device emits cavitation detecting signals in a pulse-inversion mode, and another ultrasonic transducer receives acoustic signals diffused by ultrasonic cavitation and movement of microbubbles; a transducer of another device generates cavitation signals in the pulse-inversion mode; for each cavitation detecting experiment, the detection method extracts background signals when the cavitation does not happen, respectively calculates power spectrums of the acquired cavitation acoustic signals and the background signals, calculates the subtracted power spectrum estimation and phase position estimation, and converts the power spectrum estimation and the phase position estimation into time domain signals to filter noise of a system; and an ICA method separates target signals such as broadband noise component, subharmonic and the like in cavitation acoustic signals from other signal components and extracts characteristic parameters of the cavitation acoustic signals. The detection method has high sensitivity and can perform quantitative analysis.

A speech compression system capable of encoding a speech signal into a bitstream for subsequent decoding to generate synthesized speech is disclosed. The speech compression system optimizes the bandwidth consumed by the bitstream by balancing the desired average bit rate with the perceptual quality of the reconstructed speech. The speech compression system comprises a full-rate codec, a half-rate codec, a quarter-rate codec and an eighth-rate codec. The codecs are selectively activated based on a rate selection. In addition, the full and half-rate codec are selectively activated based on a type classification. Each codec is selectively activated to encode and decode the speech signals at different bit rates emphasizing different aspects of the speech signal to enhance overall quality of the synthesized speech. The overall quality of the system is strongly related to the excitation. In order to enhance the excitation, the system contains a fixed codebook comprising several subcodebooks. The invention reveals a way to apply a pitch enhancement efficiently and differently for different subcodebooks without using additional bits. The technique is particularly applicable to selectable mode vocoder (SMV) systems.

Systems and methods for measuring environmental conditions of a sensing location, where a sensor including a measuring surface and a wire coupled in tension to the measuring surface over which ultrasonic signals may be transmitted and sensed. Signal analysis of ultrasonic signals transmitted over the tensioned wire are analyzed to measure one or more environmental conditions acting on the measuring surface.

A pressure sensor for use in measuring the pressure within fluids. The sensor comprises a medium whose material has a low coefficient of thermal expansion. The pressure can be measured by observing how signals pass through the medium at some unknown pressure and then comparing the observations to how the signals pass through the medium at a known pressure. The signals can be acoustic waves or light waves.

The invention relates to an integrated surface acoustic wave wireless pressure sensor applied to a TPMS, comprising two SAW reflection delay lines which are encapsulated for integration with a JSR membrane by a nickel conducting cylinder and a conducting adhesive, and a matched network connected with a wireless antenna, wherein, the first SAW reflection delay line comprises a single-phase unidirectional energy converter for controlling electrode width, and 3 short-circuit gate reflectors applied to pressure detection; and the second SAW reflection delay line comprises 11 short-circuit gate reflectors, wherein, 8 reflector are used for 8-bit electronic tags, and the other 3 reflectors are used for temperature detection. In the sensor, an EWC/SPUDT receives an electromagnetic wave signal from a wireless reading unit by the wireless antenna and transforms the signal into an SAW signal which is propagated along the surface of a piezoelectric substrate and is respectively reflected by the reflectors, the reflected acoustic wave is retransformed into the electromagnetic wave signal by the EWC/SPUDT and is returned to the wireless reading unit by the wireless antenna, and finally temperature and pressure detection in a tire is realized at the same time by evaluation of a phase change of time-domain response via a signal processing method.

The invention provides a vibrating cylinder transducer for measuring the pressure or density of a fluid medium comprising: a cylindrical vibrator, in use having at least one surface coupled to a fluid medium to be measured; a drive means for vibrating the cylindrical vibrator; a sensor for detecting the resonant frequency of the cylindrical vibrator; and an output coupled to the sensor, the output configured to provide an output signal indicative of the pressure and/or the density of the fluid medium; wherein the surface coupled to the fluid medium is coated in a corrosion resistant polymer layer. Preferably the corrosion resistant polymer layer is formed from parylene.

Various methods and systems are provided for diagnosing an exhaust gas recirculation valve based on crankcase pressure. In one example, a method comprises indicating a condition of a valve disposed in a first exhaust passage downstream from a cylinder exhaust valve based at least in part on a crankcase pressure.

The invention relates to a sensor (1) and a method for measuring pressure, variation in sound pressure, a magnetic field, acceleration, vibration, or the composition of a gas. The sensor (1) comprises an ultrasound transmitter (2), and a cavity (4) arranged in connection with it. According to the invention, the sensor (1) comprises a passive sensor element (3, 3') located at the opposite end of the cavity (4) to the ultrasound transmitter (2), the distance of which from the ultrasound transmitter (2) is selected in such a way that the resonance condition is met at the ultrasound frequency used, the ultrasound transmitter (2) comprises a light-construction diaphragm oscillator (9), which is thus well connected to the surrounding medium, and the sensor includes means for measuring the interaction between the ultrasound transmitter (2) and the cavity (4).

The invention relates to a device and a method for detecting a fault in a measurement device comprising a resonator and means for measuring a resonant frequency of the resonator. According to the invention, the device further includes means delivering information (S₃) representative of the quality factor of the resonator (3) at the resonant frequency.