670 results about "Wave speed" patented technology

An apparatus and methods for performing a circulatory measurement on an extremity, such as a hand, of a subject. The circulatory measurement results in the derivation of an output circulatory metric that may encompass blood pressure or various other circulatory metrics. An indicator of an input circulatory metric at a locus on the extremity is measured, such as a pulse transit time. To determine the pulse transit time, a first plethysmographic signal may be obtained at a first position on the extremity, while a second plethysmographic signal may be obtained at a second position on the extremity of the subject. A transit time characterizing a circulatory pressure wave is calculated based on the first and second plethysmographic signals, leading to derivation of a wave speed. A calibration is then applied to provide the circulatory measurement based at least on the derived wave speed and a measured indicator of a hydrostatic component of blood pressure. Calibration is provided, in certain described embodiments, by derivation of two calibration parameters, a gain and a pulse transit time at zero pressure. Methods for deriving the calibration parameters include performing measurements under distinct hydrostatic pressure conditions, and based upon a measured derivative with respect to pressure of the pulse wave velocity.

The present invention provides systems and methods to use a measured driving-point response of a nonlinear material to determine one or more elastic properties of the material. The present invention takes advantage of the full information represented by the transient component, the steady-state component, the anharmonic components, and the nonlinear response components of a measured driving-point response of a real nonlinear material, without limitation in the use of large-amplitude forces. The elastic properties are determined by forming and solving a time-domain system of linear equations representing a differential equation model of the driving-point motions of the material. Based on a single, short duration, large-amplitude driving point measurement, both linear and nonlinear properties can be determined; both large-amplitude and near-zero amplitude properties can be determined; and elastic-wave speed and elastic moduli and their variation with depth can be determined. The present invention also provides a system and a method to filter an input signal to either attenuate or preserve each of one or more selected harmonic components that are harmonics of a phase reference signal.

The invention discloses a method for locating fault of power distribution system with ineffectively grounded neutral point based on transient traveling wave, which can acquire required traveling wave signals and relatively higher detection reliability by arranging equipment only on both sides of circuit. According to the actual site condition, a non-contact electromagnetic field sensor is arranged in a transformer substation to acquire transient voltage and current traveling wave, a power distribution transformer arranged on the tail end of the circuit transmits voltage-variable traveling wave to solve the problem in acquisition of tail-end voltage traveling wave signals, and the type of the fault of the circuit can be rapidly recognized according to the amplitude and the polarity characteristics of a fault traveling wave recorded by the secondary side of the transformer. The invention provides a new fault search algorithm based on the midpoint of time to solve the problem of noncontinuous wave speed of aerial wire and cable. Accordingly, the proposal can achieve the assembly and the operation of the equipment without adding extra primary equipment of the system and powering off the circuit, thus saving the cost and reducing the complex degree of the project. Practical operation shows that the method can locate a fault within a range of plus or minus 100 m.

A method for measuring a mechanical property of a subject includes using an ultrasonic transducer to apply ultrasonic vibration pulses to a vibration origin in the subject in an on-off time sequence in order to impart a harmonic motion at a prescribed frequency to the subject, and when the vibration pulses are off, using the same transducer to apply ultrasonic detection pulses to a motion detection point and to receive echo signals therefrom in order to sense the harmonic motion on the subject at the motion detection point. From the harmonic signal information, a harmonic signal is detected and a characteristic such as amplitude or phase of the detected harmonic signal is measured. The mechanical property is calculated using the measured characteristic using for example a wave speed dispersion method.

The invention discloses an ultrasonic wave-based coal dust concentration dynamic detection system and coal dust concentration dynamic monitoring method of mine. Sixteen ultrasonic sensors are fixed on the inner wall of an inner ring in a uniform angle manner, and every ultrasonic sensor simultaneously has ultrasonic wave emitting and receiving functions; all signal wires are commonly connected to a multi-core plug on an outer ring, the multi-core plug is connected with a programmed multipath toggle switch through a shielded multi-core cable, the programmed multipath toggle switch is respectively connected with a voltage pulse generator and an ultrasonic data acquisition device through wires, the voltage pulse generator is connected with the ultrasonic data acquisition device through a wire, and the ultrasonic data acquisition device is connected with a data processing center through a wire. An existing single-emitting and single-receiving detection mode is improved to a cycle single-emitting multi-receiving CT detection mode, and an ultrasonic wave speed CT image and an absorption coefficient CT image are adopted to reflect the coal dust concentration distribution, so the detection accuracy is improved.

A method and apparatus for detecting and locating leaks in buried pipes is disclosed in which ground penetrating radar, induction, acoustic, and vacuum excavation systems are selected based on soil conditions and then employed in selected combinations. The conductivity and wave speed of the soil are used in the selection process and in the process of detecting and locating a leak based on the measurements obtained from the selected combination of detection systems.

The invention discloses an intelligent positioning method of mine microquake sources, which is a microquake resource intelligent positioning system which comprehensively considers various influencing factors and targets, and integrates with sensors distribution-noise wave filtration-microquake source positioning analysis-three-dimensional display in to a whole. The method realizes the real-time analysis and the forecast of the incubation, the development and the occurrence of mine underground geological disaster through a self-developed procedure, solves the defects that the traditional sensors distribution method is not systematic, the noise wave filtration is incomplete, the microquake wave speed model is not exact and the positioning method is easily diffused, and has the characteristics of friendly operation interface, good noise wave filtration performance, exact, convenient and fast microquake source positioning analysis, visual and pictorial result display, and wide application range. The method has wide application value in the fields of mineral engineering, water conservancy and electric power engineering, petroleum engineering, soil engineering and underground engineering and the like.

The invention discloses a fault positioning method for a transmission line and belongs to the technical field of power systems. The fault positioning method comprises the following steps: arranging a Rogowski coil-based broadband core-through traveling wave detection device on the high-voltage transmission line; acquiring a current traveling wave signal of a three-phase line; performing singular value detection by applying the phase mode conversion and wavelet mode maximum principle; accurately identifying the traveling wave line mode wave head, and accurately determining the wave head arrival time by using a GPS high-precision clock; and measuring the wave speed of real-time traveling wave mode on line according to different wave head time difference information to realize accurate fault positioning. The fault positioning method has the advantages of effectively avoiding two main factors influencing the traveling wave fault positioning precision, along with high positioning precision and accurate and reliable fault positioning result.

A circular ring wave pool having an island in the center, the pool water depth becomes deeper the farther away from the island to the outside pool wall. A plurality of wave generators encompass the entire outer wall deep side of the pool. All wave generators point directly to the center of the island. Wave generators are synchronized in their action to produce waves that travel around the circular ring shaped pool in an endless loop therefore creating a traveling surfing wave that never ends. Many waves can be generated simultaneously creating a plurality of endless waves moving around the island. The sloping beach is at an angle to create a hollow tube breaking wave depending on wave speed and size. Hundreds of surfers can be in the pool at the same time all sitting out past the wave breakpoint waiting for an available wave to pass.

The invention provides an exoskeleton wearable upper limb rehabilitation robot, which comprises a shoulder joint exoskeleton, an elbow joint exoskeleton, a wrist joint exoskeleton and a hand exoskeleton, wherein the shoulder joint exoskeleton has two degrees of freedom; the elbow joint exoskeleton has two degrees of freedom; the wrist joint exoskeleton has one degree of freedom; and the hand exoskeleton has three degrees of freedom, namely the robot have eight degrees of freedom. The exoskeleton wearable upper limb rehabilitation robot is driven by using a harmonic wave speed reducer and a disc type motor serving as a high-power motor to realize zero-rotation error and the good fit of driving and joints of patients. The exoskeleton wearable upper limb rehabilitation robot can be driven by a storage battery, the problem of limit of activity range in the conventional rehabilitation device is solved, and the robot is portable.

The invention provides a method which uses transient online diagnosis coupling frequency response to position the leakage of natural gas pipeline, and relates to a natural gas pipeline failure detection and positioning method which can solve the problems that the existing method for detecting and positioning the leakage of the natural gas pipeline can not detect in real time, has long detection period, low positioning precision and high error report rate; real-time pressure value and real-time flux value are respectively collected at the upstream and downstream of the pipeline; the real-time downstream pressure value and the real-time flux value when the pipeline runs stably are reduced by the practical real-time pressure value and the practical real-time flux value at the downstream; if both of the two differences exceed the valve value, the leakage is considered to occur, otherwise the values are collected again; an excitation pressure wave is generated at the downstream end of the pipeline and the wave speed of the response wave of the excitation pressure wave is gained; according to the wave speed of the excitation pressure response wave and the time difference when the excitation pressure response wave is transmitted to the upstream and the downstream, the position of the leakage point is gained. The measurement and collection of the values are completed by normal equipments and the method can be used both in the built pipeline or pipelines under construction.

The invention discloses a system for testing rock damage and permeability under the coupling effect of temperature stress and circumferential seepage. The system comprises a frozen-heave force test device and a permeation test device, wherein the permeation test device comprises a pressure chamber for loading a rock test piece to be tested, a pressure loading device, a permeation pressure increasing and measuring device, a water bath heating device, an ultrasonic damage test device and a data acquisition device. The invention further discloses a method for testing rock damage and permeability under the coupling effect of temperature stress and circumferential seepage. The method comprises the following steps: carrying out repeated freezing-thawing tests on a rock by the frozen-heave force test device, measuring the frozen-heave force change of the rock test piece, putting the rock into the pressure chamber, applying a pressure to the rock test piece by the pressure loading device, and testing a rock permeation coefficient k and ultrasonic wave speed transmission time t under the action of flowing liquid with different temperatures and pressures so as to make a research on rock damage and permeability.

The invention discloses a fault single end positioning method of a power transmission line based on traveling wave multi-scale information, which comprises the following steps of: selecting different phases as reference phases according to different fault types and carrying out phase-mode transformation on a fault current traveling wave signal of the power transmission line to obtain a fault current traveling wave mode signal for fault positioning; carrying out continuous wavelet transformation on the mode signal, extracting modulus maximums of wave heads of first and second traveling waves on each wavelet transformation coefficient and corresponding moments of the modulus maximums and judging a section where the fault occurs and determining frequency components of the wave heads of the first and the second traveling waves for positioning according to wavelet transformation modulus maximums to obtain mode wave speeds of the two traveling waves with different frequency components and arrival moments of the wave heads; and finally comprehensively calculating the fault distance of the power transmission line in combination with the mode wave speeds and the arrival moments of the two traveling waves. In the fault single end positioning method of the power transmission line, the frequency components, the mode wave speeds and the arrival moments of the wave heads of the traveling waves are accurately determined by utilizing the multi-scale information of the traveling waves so as to accurately calculating the fault distance of the power transmission line.

The invention relates to a single-end fault ranging method based on initial reversed-polarity directional traveling wave detection, which can effectively realize single-end traveling wave fault ranging and has high reliability and high accuracy. The method comprises the following steps: (1) when a traveling wave fault ranging device is started, testing the arriving time t1 of the line modular component of the initial traveling wave of a fault, and extracting traveling wave signals in the time interval [0, 2L / v], wherein L indicates the length of the line, and v indicates the wave speed of theline module component; (2) testing the initial reversed-polarity directional traveling wave in the time interval, calculating the difference of the arriving time of the line modular component of the initial reversed-polarity directional traveling wave and the arriving time of the line modular component of the initial traveling wave of the fault, determining whether the fault is a nearby fault or a remote fault with reference to Curve Chart 3, and accordingly determining the section with the fault point; (3) judging the properties of the second arriving wave head through the determined fault section; and (4) determining final ranging results through the initial traveling wave and the wave head of the second traveling wave of the fault.

The invention relates to a robot joint based on harmonic reducers, which comprises a motor, an encoder connected with the motor, a harmonic reducer connected with a rotor of the motor, and a transmission mechanism connected with the harmonic reducer; wherein, the harmonic reducer comprises a wave generator, a flexible wheel outside the wave generator, a fixed steel wheel outside the flexible wheel and a rotary steel wheel; the transmission mechanism comprises a housing fixedly connected with the fixed steel wheel of the harmonic reducer and an end cover fixedly connected with the rotary steel wheel of the harmonic reducer; a bearing is arranged between the housing and the end cover. The robot joint has the advantages of high drive ratio, high reliability, compact structure, ability to substitute the robot joint in the prior art, gradual decrease with the size of the harmonic reducer, higher applicability to joint transmission of miniature robots, and wide application prospect.

The invention discloses a satellite-ground synchronization method for an on-satellite processing beam-hopping satellite communication system, and belongs to the technical field of satellite communication. By periodically inserting the beam hopping plan corresponding to the beam position into the downlink frame, the ground terminal can be effectively assisted to realize the fast access of the uplink in the beam hopping environment. In addition, in combination with the working principle of the phased-array antenna, the satellite-borne time transmission method oriented to phased-array antenna beam hopping application is provided, and the time reference consistency among multiple phased-array antennas and between each wave position receiving beam and each wave position transmitting beam is effectively ensured. The synchronous control time sequence of the phased-array antenna is provided, the beam switching serial data and the wave speed switching control pulse signal are separately transmitted, the beam switching serial data are sent in advance before the beam switch control pulse is sent, the protection time in the beam switching process is shortened, and the transmission efficiency of the beam hopping application is effectively improved.

The invention provides a method for carrying out ultrasonic inspection on residual stress of an aluminium alloy pre-stretching board by water immersion, belonging to the field of non-destructive inspection. The method comprises the following steps of preparing a reference block; carrying out measurement and calibration; measuring the residual stress. In the method, the water immersion method is adopted, and the temperatures in stress calibration and stress measurement processes can be ensured to be consistent by controlling the water temperature not to be changed, thus eliminating the effects of temperature difference on the ultrasonic wave speed and eliminating temperature errors; besides, an automatic scanning frame is adopted instead of manual scanning, so that the distance between a probe and the surface of a material to be measured in the measurement process can be ensured not to be changed, thus eliminating the effects of coupling condition difference on sound propagation time and eliminating the coupling errors. The method is beneficial to non-destructive evaluation of the near surface residual stress of the aluminium alloy pre-stretching board.

The invention discloses a high-speed rail health monitoring system based on ultrasonic guide wave and a wireless network. A vehicle-mounted center processing and decision module sends a detection instruction to an ultrasonic guide wave exciting module through a wireless network transmission module; the ultrasonic guide wave exciting module generates excitation wave; the ultrasonic guide wave is generated in a rail and transmitted to an ultrasonic guide wave signal receiving and storage module; the receiving and storage module digitalizes ultrasonic guide wave signals, stores the signals and transmits the signals to the vehicle-mounted center processing and decision module; and the ultrasonic guide wave signals are filtered and enveloped, features of a wave packet arrived by the ultrasonic guide wave are extracted, the attribute and the actual wave speed of the wave packet in the waveform signals are judged and compared with undamaged condition information in a database, damage features in the waveform signals are extracted, whether damage exists in a high-speed rail or not is judged, the damage degree is judged, and the position of the damage is assessed. Through the system, the detection speed and the detection capability of micro damage of the rail are improved, and the time for occupying the high-speed rail is reduced.

The invention relates to a system and a method for distribution network fault locating based on an improved double-terminal traveling wave method. The system comprises a terminal measurement module and a control center host computer, wherein the terminal measurement module is composed of a sensor module, a microprocessor module, a wireless communication module and a power supply module. The method comprises the following steps: a current traveling wave signal measured by a current transformer is calculated to obtain each current phase with a time scale; the phase current is decoupled, and a line mode component is selected as a traveling wave propagation mode for fault locating; an obtained traveling wave signal is uploaded to the control center host computer; the head of a travelling wave is detected, and rapid intrinsic mode decomposition is carried out on the line mode component; the arrival time of the travelling wave is determined; the wave speed is measured; and a fault is located. By adopting the system and the method of the invention, higher detection accuracy is achieved, the consistency of wave speeds of a fault traveling wave in three line sections formed by a fault point and three measuring points is ensured, and accurate online fault traveling wave speed determination is realized.

The invention provides a micro-earthquake focus rapid positioning method based on an arrival time difference database, and belongs to the earthquake focus positioning technology field. The micro-earthquake focus rapid positioning method comprises the steps that a geological numerical model of a monitoring area is established, and mesh division is carried out, and every mesh point is adopted as a characteristic earthquake focus point; by combining with the characteristic earthquake focus point, a sensor position coordinate, and an earthquake focus wave speed, a characteristic earthquake focus point arrival time difference database is established; by using a waveform information acquisition system, the time of the earthquake source waves arriving at different sensors is extracted from waveform signals received from the sensors; the arrival time difference between any two sensors is calculated, and the arrival time difference matrix of the earthquake focus is established, and the matching searching of the arrival time difference matrix and the characteristic earthquake focus point arrival time difference database is carried out to realize the real-time rapid positioning of the earthquake focus. During an actual micro-earthquake monitoring project, the characteristic earthquake focus point arrival time difference database is established in advance, and the function optimization iteration solution of the earthquake focus is not required, and therefore time required by the earthquake focus positioning is greatly reduced, and rock mass engineering dynamic disaster early warning time is effectively reduced.

The invention relates to the field of two-phase / multi-phase flow measurement, aims to realize the non-intrusive and high precision synchronization acquisition of the flow parameters of a liquid film in (outside) a pipeline and temperature field distribution, and is used for the deep study of a liquid film flow characteristic, a heat transfer characteristic and the like. The employed technical scheme is that according to the liquid film temperature field and flow field simultaneous measurement method based on laser induced fluorescence, when a liquid film with dissolved fluorescent dye forms a dynamic liquid film in a pipeline inner / outer wall or a flat panel, a liquid film fluorescence image is taken through a high speed camera, for a same taken fluorescence image, based on a high speed calibration parameter, the geometric feature of the liquid film fluorescence image is accurately extracted, and flow field characteristics comprising a liquid film thickness and a velocity are obtained. At the same time, based on a calibrated temperature-fluorescence intensity calibration curve, laser intensity calibration and a fluorescence intensity extraction method, a liquid film fluorescence image brightness is accurately extracted, and the instantaneous and time averaged temperature field distribution of the liquid film are obtained. The method is mainly applied to a two-phase / multi-phase flow measurement occasion.

The invention discloses a method and a device for synchronously measuring rock sound wave and acoustic emission. The method comprises the following steps: A, putting sealing pressing ends for transmitting and receiving a sound wave signal at two ends of a rock sample, and keeping a longitudinal wave probe and a transverse wave probe inside the sealing pressing ends identical in the vertical direction; B, arranging and fixing an acoustic emission receiving probe outside the rock test sample; C, starting a sound wave and acoustic emission testing system, and starting a rock pressure machine for a loading experiment till the rock sample is damaged; D, performing aftertreatment on acquired data to obtain the number and the position and the ultrasonic speed change information of acoustic emission events of the rock; and E, respectively connecting a sound wave testing device and an acoustic emission testing device with experiment pressure machine base adapters, and connecting with a data acquisition and processing system through corresponding adapters. The method is feasible and simple and convenient to operate, synchronous acquisition of sound wave and acoustic emission information in rock mechanics tests is achieved, and positioning of a rock acoustic emission position is achieved.

The invention discloses a modularization mechanical arm joint with variable freedom. Modularization design idea is introduced into the design of a light mechanical arm, and through a plurality of mechanical arm joints, modularization mechanical arms with different freedom degrees can be formed by splicing. The modularization mechanical arm joint comprises an output flange shaft formed by an output flange and an output shaft, a harmonic wave speed reducer, a hollow shaft motor, a braking device and a double-coded-disc locating mechanism. The harmonic wave speed reducer and the output flange are fixed. Meanwhile, the harmonic wave speed reducer and a hollow shaft of the hollow shaft motor are fixed. The hollow shaft rotates, and after speed reducing through the harmonic wave speed reducer, the output flange is driven to rotate. The braking device is used for carrying out emergency braking during an emergency situation. The double-coded-disc locating mechanism is used for obtaining the speed information of the hollow shaft and the position information of the output shaft. Control of the parts is achieved through a servo driving circuit. The modularization mechanical arm joint has the advantages that the mechanical arm can have strong environment adaptation capacity, and high function expandability, flexibility and adaptability are achieved.

A vacuum sealed SAW pressure sensor is disclosed herein, which includes a sensing element configured as a SAW device (e.g., SAW resonator or SAW delay line) supported by a thin diaphragm. The substrate material can be implemented as a quartz wafer (i.e., a “base” wafer). The SAW device can be configured on one side of the wafer and the diaphragm etched on the opposite side. A quartz micromachined pressure sensor can thus be realized, which operates based on a variation of the surface wave velocity of a SAW device situated on the thin diaphragm. The SAW sensor is generally sealed in a vacuum and diaphragm sustains the sensor, thereby implementing a sensor on a wafer scale while allowing for a cost reduction per chip.

The invention relates to an ultra-high-voltage direct-current transmission line neural network double end fault location method based on the high frequency amount attenuation characteristic, and belongs to the technical field of relaying protection on high-voltage direct-current transmission systems. According to the method, on the basis of the attenuation characteristic generated when faults are spread on a line with high frequency amount, the mathematic relations between the fault distances and the ratio of a head wave amplitude value of a traveling wave of a fault voltage reaching a rectifying side range unit to a head wave amplitude value of a traveling wave of a fault voltage reaching an inversion side range unit are derived; the ratio of head wave amplitude values of traveling waves of fault voltages detected by rectifying side range units in different frequency bands to head wave amplitude values of traveling waves of fault voltages detected by inversion side range units in different frequency bands are selected to serve as an input sample set of a BP neural network, the fault distances serve as an output sample set, the neural network is trained to generate a fault location neural network model; after the fault location neural network model is formed, testing samples are input the trained model to obtain the fault location result. The method avoids the problem that wave speed is difficult to determine with a traditional double-end traveling wave fault location method.

A fiber grating strain sensing system is used to locate and characterize a high speed environmental event that destroys one or more fiber grating strain sensors as it passes them. The system is very suitable for the detection and characterization of a high intensity pressure wave such as a blast wave due to a detonation. A fiber grating strain sensor is oriented so that the high speed environmental effect passes over it and its reflective spectral profile changes as portions of the fiber grating strain sensor are destroyed. The reflective spectral profile from one or more fiber grating strain sensors are then mixed with the spectral profile of an optical filter onto a high speed output detector. A reference detector may be used to normalize the output signal. The spectral profiles of the fiber grating strain sensors and optical filter may be arranged in several ways that are effective including substantially matching both profiles, establishing opposite spectral slopes and utilization of an optical filter with a substantially flat spectral profile.

Tightening of a bolt is controlled by monitoring the change in round trip time of propagating longitudinal ultrasonic waves through the bolt and the reflection of these waves at the end of the bolt. The round trip time of the longitudinal waves through bolt is continuously measured and monitored in real-time. Elongation of the bolt as it is being tightened is determined based on the change in the round trip time of the longitudinal waves, which provides the level of bolt tension and joint clamp load. In determining the bolt elongation, an elongation-dependent wave speed has been formulated and used in-real time. When the elongation of the bolt reaches a predetermined level, tightening is automatically stopped.

The invention discloses a method for intravascular ultrasound multi-slice shear wave elastography. The method comprises the following steps of recording an original ultrasound echo signal of a tissue to be detected; enabling an interventional ultrasound array probe to generate acoustic radiation force by virtue of a short-pulse signal controlled by a computer; emitting ultrasonic pulse beams for many times to accept and detect a propagation process of shear waves generated by the acoustic radiation force; analyzing the propagation speed of the shear waves in the tissue to be detected to obtain a wave speed distribution image of the shear waves in the tissue; performing wave speed mapping on the shear waves at each position in the tissue to be detected to obtain a quantitative elastic image of the intravascular tissue. The method has the advantages of real time performance, quantification, high speed, high resolution and the like; a multi-array element intravascular transducer array is used for performing vascular wall tissue elastic information quantitative analysis to excite and track the shear waves; the further popularization and application of intravascular elastography are favorably promoted, and the early diagnosis capability of people in cardiovascular diseases is enhanced.