Patents
Literature
Hiro is an intelligent assistant for R&D personnel, combined with Patent DNA, to facilitate innovative research.
Hiro

204 results about "Group velocity" patented technology

The group velocity of a wave is the velocity with which the overall envelope shape of the wave's amplitudes—known as the modulation or envelope of the wave—propagates through space. For example, if a stone is thrown into the middle of a very still pond, a circular pattern of waves with a quiescent center appears in the water, also known as a capillary wave. The expanding ring of waves is the wave group, within which one can discern individual wavelets of differing wavelengths traveling at different speeds. The shorter waves travel faster than the group as a whole, but their amplitudes diminish as they approach the leading edge of the group. The longer waves travel more slowly, and their amplitudes diminish as they emerge from the trailing boundary of the group.

Super-Resolution Formation Fluid Imaging

Cross-well electromagnetic (EM) imaging is performed using high-power pulsed magnetic field sources, time-domain signal acquisition, low-noise magnetic field sensors, spatial oversampling and super-resolution image enhancement and injected magnetic nanofluids. Inter-well images are generated mapping electromagnetic (EM) signal speed (group velocity) rather than conductivity maps. EM velocity maps with improved resolution for both native and injected fluids are provided.
Owner:SAUDI ARABIAN OIL CO

Ultrasonic Lamb wave-based butt weld nondestructive testing method

The invention concretely relates to an ultrasonic Lamb wave-based butt weld nondestructive testing method and belongs to the ultrasonic guided-wave nondestructive testing field. An excitation source is loaded at the end of a weld joint. Two piezoelectric patches are pasted on the upper surface and the lower surface of a plate symmetrically and excited. The generated weld joint guided-wave mode propagating along the weld joint has high energy and slow attenuation, and the long-distance testing problem can be solved. The testing system is shown in the figure, and composed of a function generator (1), a power amplifier (2), piezoelectric patches (3), an oblique incidence-type piezoelectric ultrasonic sensor (4), an oscilloscope (5) and a computer (6). By utilizing the testing system, when the ultrasonic Lamb wave encounters flaws of the weld joint, flaw echoes are generated. According to the time difference between the excitation waveforms and the waveforms of flaw echoes and the group velocity of the weld joint guided-wave mode, the distance from the flaws to the excitation source can be obtained, and therefore the effective locating of weld joint flaws can be achieved.
Owner:BEIJING UNIV OF TECH

Method for nondestructive detecting length of high speed highway guardrail upright post by ultrasonic guided wave

A method of using ultrasonic guided wave to detect the length of grate column of half buried under different highway roadbed, belongs to nondestructive testing field. The method is to determine parameters of grate column before buried calculate group velocity dispersion curve of grate column before buried; select detection frequency from the curve and input the arbitrary function generator to form a single audio signal through the power amplifier module, switch modules, guided wave transceiver components, stimulate the vertical axisymmetric guided wave mode in the vertical column; the guided wave modal generate end echo when encounter the end of the column, the end echo is sent to oscilloscope through guided wave transceiver components and switch modules, determine the corresponding time of end echo, obtain the group velocity from the group velocity dispersion curve, multiple the group velocity with the echo time, divided by 2 to obtain the length of column. The present invention has the advantages of do not need to consider surrounding medium of column, high detection accuracy and of low cost.
Owner:BEIJING UNIV OF TECH

Methods and apparatus for extracting first arrival wave packets in a structural health monitoring system

Methods and apparatus for extracting the first arrival wave packet of an acoustic signal in a structural health monitoring (SHM) system include receiving an acoustic signal transmitted between two transducers thereof. Electromagnetic cross-talk is removed from the signal. Signal amplitude threshold values used for picking out the first arrival wave packet are chosen based on signal characteristics or chosen adaptively as the value that leads to the minimum variance of the group velocity estimates of all the actuation-sensing transducer pairs. The group velocity is estimated as the known actuator-sensor distance divided by the propagation time of the first wave packet of which the envelope exceeds a candidate threshold value. The first arrival wave packet is determined as the signal segment where the signal envelope first exceeds the chosen amplitude threshold and the segment length exceeds a specified threshold of time width.
Owner:ACELLENT TECH

Methods and apparatus of entangled photon generation using four-wave mixing

A non-linear optical device is provided. The device comprises an optical disk or ring microresonator fabricated from a material that exhibits an optical nonlinearity able to produce degenerate four-wave mixing (FWM) in response to a pump beam having a pump frequency in a specified effective range. The microresonator is conformed to exhibit an angular group velocity minimum at a pump frequency within the specified effective range such that there is zero angular group velocity dispersion at the pump frequency. We refer to such a pump frequency as the “zero dispersion frequency”. In embodiments, excitation of the resonator by a pump beam of sufficient intensity at the zero-dispersion frequency causes the resonator to emit a frequency comb of entangled photon pairs wherein the respective frequencies in each pair are symmetrically placed about the zero-dispersion frequency.
Owner:NAT TECH & ENG SOLUTIONS OF SANDIA LLC

System and method for detecting thickness of industrial boiler scale based on SH (Shear) wave

The invention relates to a method for detecting the thickness of industrial boiler scale by utilizing an SH (Shear) wave which is sensitive to an attachment on the surface of a plate layer, belonging to the field of nondestructive inspection of ultrasonic guided waves. In the method, firstly, a dispersion curve with different scale thicknesses is drawn by utilizing a dispersion equation for SH wave propagation in a double-layer structure to obtain a variation curve of SH0 modal group velocity changing along with the increase of the thickness of the scale, and then a high detection frequency and a low detection frequency respectively corresponding to thinner scales and thicker scales are further obtained. A detection system is shown as the drawing and comprises a function generator (1), a power amplifier (2), a change-over switch (3), an EMAT (Electromagnetic-Acoustic Transducer) sensor (4), an oscillometer (5) and a computer (6). The group velocity of an SH0 modal in a structure formed by a boiler and scales can be measured by the system, and the thickness of the scale can be obtained according to the corresponding curve of the group velocity and the scale thickness by the calculation, thereby the online and nondestructive testing on the thickness of the industrial boiler scale is realized.
Owner:BEIJING UNIV OF TECH

Bunting position and energy measurement method based on wave propagation time and energy function

The invention relates to a bunting position and energy measurement method based on a wave propagation time and energy function. According to the method, a plurality of sensors are arranged below a touch equipment perception panel so as to response a blast wave signal generated by bunting; blast wave signal energy and arrival time therefore are detected; according to a principle that the blast wave group velocity is similarly equal in each direction on the aspects of isotropic or quasi-isotropic structure, the bunting position is analyzed and calculated; and according to the relationship that the bunting dynamics and the blast wave signal energy are in direct proportion, the blunting energy is analyzed and calculated. According to the bunting position and energy measurement method based on the wave propagation time and energy function, which is disclosed by the invention, the method in the prior art that a group sensor, such as an array sensor, needs to be arranged to sense the bunting dynamics is changed, and the amount of required sensors is reduced so as to reduce the total weight, the complexity and the energy consumption of the touch equipment, and the cost is greatly lowered. The bunting position and energy measurement method based on the wave propagation time and energy function can be used for electronic equipment with a propagation panel, such as a touch screen, a game control panel and a shooting target, and performs the functions of assisting or replacing the traditional positioning method based on the technology, such as resistance and capacitance.
Owner:BEIJING TAIFANG TECH CO LTD
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products