226 results about "A wave amplitude" patented technology

A computer-based method for positioning an endovascular device in or near the heart using electrocardiogram (ECG) signals is provided. The computer-based method includes receiving an endovascular ECG signal, associated with an endovascular device, including a plurality of waveforms, each waveform having at least a P-wave component, processing the endovascular ECG signal, over a plurality of predetermined time periods, to calculate a P-wave amplitude and a spectral power for each predetermined time period, determining a maximum P-wave amplitude from the plurality of P-wave amplitudes, and an associated maximum spectral power from the plurality of spectral powers, associating the maximum P-wave amplitude and the maximum spectral power with a predetermined location in or near the heart, calculating a location of the endovascular device, for each predetermined time period, based on a ratio of the P-wave amplitude to the maximum P-wave amplitude and a ratio of the spectral power to the maximum spectral power, and displaying the location of the endovascular device to a user.

A wave amplitude modulator for modulating a transmitted electromagnetic wave includes one or multiple self-gated capacitively coupled pair(s) of electron layers such as semiconductor or semimetal layers. Two electrical contacts are placed to each layer of electrons of the self-gated pair(s), and a power source is electrically connected to them. The power source, by varying the voltage applied between layers of electrons, tunes the electron density thereof, thereby adjusting the optical conductivity thereof, and the change in the optical conductivity of the layers of electrons causes an amplitude modulation of the transmitted electromagnetic wave passing through the capacitively coupled layers of electrons.

A spring is formed of a relatively thin sheet of spring material which is constricted and held in place at each end forming a bell curve being located between two substantially planar members. As additional compressive force is applied in the vertical direction, the curve then compresses and starts to form sine waves. The greater the force, progressively higher the wave frequency with lower amplitude would form. When the force is removed, the flexible material returns to its original shape. The force needed to shift the curve (increase the number of waveform) increases at an exponential rate, as opposed to the linear rate of most normal springs. The maintenance force of new stable state is considerable less than the threshold force. Such a relatively flat spring with an exponential spring rate and self dampening through phase change has a number of useful applications for automotive and industrial use.

The invention relates to a PWM overmodulation method based on an optimized quasi sine flat modulating wave. The method is characterized in that firstly, one quasi sine flat wave is established to serve as the modulating wave, a triangular carrier wave is modulated, and then a three-phase PWM overmodulation algorithm is adopted for overmodulation. According to the method, three-phase PWM is generated by adopting the triangular carrier wave, the largest output linear voltage fundamental wave amplitude value of the three-phase PWM in a linear area is 19% higher than that of SPWM, and therefore the direct-current voltage use ratio is remarkably improved.

The invention discloses a method for detecting early-stage mechanical property degradation of a material by utilizing nolinear rayleigh wave, belonging to the field of nondestructive testing. The invention comprises the following steps: inputting frequency, periodicity and other parameters of a selected transmission signal to a signal generator to generate a required single sound signal, and determining the incident angle theta of the transmission signal according to the wave speed of a piece to be tested; collecting a non-linear Rayleigh wave signal in equal time intervals in the stretching or fatigue loading process of the piece to be tested; and carrying out Fourier transform to obtain basic wave amplitude and secondary harmonic amplitude, computing the ultrasound non-linear coefficient beta, and knowing the early-stage mechanical property degradation of the piece to be tested according to beta. In the invention, a sensor is directly arranged at the edge of the piece to be tested to transmit and receive Rayleigh wave to improve the excitation and receiving efficiencies of the signal and decrease the non-linear influence brought by the coupling of the sensor and the piece to be tested; and both the excitation and the receiving adopt the piezoelectric sensor, thus being more applicable to engineering actual situation, and realizing continuous on-line detection on the piece to be tested.

The invention discloses a system for measuring ship draft and river water level based on special micro wave amplitude and a water gauge, belonging to the measurement field of the ship draft and the river water level and solving the technical problem that a measurement field video image comprising high-precision ship draft or river water level data can be displayed in real time by just using one miniature video picture. In the system, a technology of displaying the average height of irregular wave surfaces, a special micro technology of wave amplitude and ship water gauge maker or river water gauge, a video image monitoring system technology, an automatic tracking and shooting target technology of miniature camera equipment and the like are mainly adopted. The system has the advantages that visual, real, objective, just, clear and high-precision measurement data and measuring field live action which can be put on records is provided in real time by the video image and can be transmitted outside. The system has low cost, is simple and practical, is convenient to operate, carry and maintain and is energy-saving and environmentally-friendly, and the automatic measurement of the ship draft and the water levels of the river and the like is easily achieved.

The invention relates to a non-linear Lamb wave method for measuring stress distribution in a metal sheet, and discloses a stress distribution detection method based on the non-linear Lamb wave mixingtechnology. The stress distribution detection method is suitable for stress distribution detection and positioning of a stress concentration area in plate structures, and belongs to the field of non-destructive detection. The non-linear Lamb wave method comprises the steps that firstly excitation frequencies of two fundamental frequency waves are determined according to a measured object and thenon-linear Lamb wave mixing resonance conditions; two rows of A0 mode waves are excited in opposite directions at the left end and the right end of the specimen, and a sum-frequency S0 signal is received at a certain position between the excitation signals to detect the non-linear mixing stress of the plate structure; by changing the excitation delay of the excitation signals, different positionsof the specimen are swept and checked in mixing, and the amplitude of the mixing wave is extracted; and finally, according to the change rule of sum-frequency difference signal amplitude with mixing position, the stress distribution of the metal plate can be detected, and the stress concentration area can be positioned.

The invention provides an adjustable amplitude automatic gain compensation method for ultrasonic thickness gauges, comprising: a, feeding back echo strength and setting a constant gain to obtain a reference gain voltage; b, in a measurement thickness range, using ultrasonic transmission to integrate reflected ultrasonic wave to obtain gain compensation voltage; c; laminating the gain compensation voltage and the reference gain voltage to generate a final gain control voltage. The invention further provides an adjustable amplitude automatic gain compensation circuit. Compared with the amplitude compensation curved line and deep gain compensation method applied in ultrasonic inspection, the adjustable amplitude automatic gain compensation method has high automatic degree and high response speed, and is closed relative to field test condition, thereby resolving the problems of prior compensation methods such as low automatic degree, low response speed and inconsistence to field test. The adjustable amplitude automatic gain compensation method utilizes the theory of integral circuit to generate a gain voltage curved line to design an ultrasonic thickness test amplitude automatic compensation circuit, and therefore, compared with other time and distance compensation methods, the method has the advantages of simple design, low cost and reliable application.

The present invention discloses a distribution line adaptive protection method and system based on traveling waves, belonging to the technical field of line protection. At measurement points, far awayfrom a bus, of a fault line, the fault phase initial current traveling waves of the single-phase grounding faults are large, and the non-fault phase is zero; at measurement points, close to the bus,of the fault line, the fault phase initial traveling wave amplitude of the single-phase grounding faults are twice of the non-fault phase, and the polarity is opposite. At the measurement points, faraway from the bus, of the fault line, the fault phase initial current traveling waves of the two-phase grounding faults are large, and the non-fault phase is zero; and at the measurement points, closeto the bus, of the fault line, the initial current traveling waves of the fault phase and the non-fault phase of the two-phase grounding faults have no obvious features. The distribution line adaptive protection scheme can perform accurate and reliable motions for all the types of short-circuit faults. The propagation of the initial traveling waves cannot be influence by a grounding resistance condition, and therefore, the protection scheme can respond to the high-resistance grounding faults.

The invention belongs to a dynamic pressure regulating technology, and relates to a dynamic pressure regulator based on the piezoelectric ceramic technology. The dynamic pressure regulator comprises a resonance pipeline, a piezoelectric stack and a voltage energized circuit, wherein the voltage energized circuit comprises a sine voltage signal generator, a power amplifier and an LC resonance circuit. The output end of the LC resonance circuit is connected with the piezoelectric stack which is positioned at the bottom of the resonance pipeline, the inside of the resonance pipeline is filled with liquid medium, and the top of the resonance pipeline is provided with a mounting hole for mounting a pressure sensor to be regulated. In the invention, the frequency of sine pressure wave in the resonance pipeline is convenient to adjust. The operating frequency of the dynamic pressure regulation is higher, and the sine pressure wave under resonance points has great amplitude and little degree of distortion. The amplitude of the sine pressure wave is not reduced along with the increase of the order of the resonance points, and the amplitude of the pressure wave under some high resonance points is even far greater than the amplitude of the pressure wave under low resonance points. The degree of distortion of the sine pressure wave is not increased along with the increase of the frequency.

The invention discloses an incident wave control method for an electromagnetic-force Hopkinson pressure bar and torsion bar experiment loading device. The incident wave control method is used for solving the technical problem of the existing electromagnetic force based Hopkinson pressure bar and torsion bar experiment methods that the practicability is poor. The technical scheme is as follows: precise control is carried out on the amplitude and pulse width of loaded incident waves by using relationships between the electromagnetic-force incident waves and discharge voltage, discharge inductance, discharge capacity, discharge resistance and secondary coil thickness, so that the maximum pulse amplitude and rising edge slope of the incident waves are increased. According to the method disclosed by the invention, the underdamped working condition of an electromagnetic force stress wave generator is guaranteed through reducing the discharge resistance, so that the maximum amplitude and rising edge slope of the incident waves are increased; by adopting a cake-shaped discharge coil and a 10mm-thickness secondary coil, the maximum pulse amplitude of the incident waves is further increased and can reach 325MPa, and the precise control on the amplitude of the incident waves in the range of 10-325MPa and the pulse width of the incident waves in the range of 100-500 microseconds is realized.

The invention provides a column type multi-point nanometer friction microwave power generation device. The device comprises a hollow cylindrical floating drum, a solid cylinder and friction electric generator sets. The solid cylinder is located at a center position of the cylindrical floating drum, and there are at least four friction electric generator sets which are arranged in a gap between thecylindrical floating drum and the solid cylinder at equal intervals. The invention provides the column type multi-point nanometer friction microwave power generation device which is simple in structure, high in power generation efficiency and good in stability. A wave amplitude in a severe environment can be reduced by using a structure of the cylindrical floating drum to the greatest extent. Friction of relative motion of the friction electric generator sets and the relative motion of a spring are used to promote the friction between nanometer friction generator films so as to carry out waveenergy and electric energy conversion. The wave energy and electric energy conversion can be performed through using a wave amplitude difference between the floating drum and waves and the energy isprovided for coast power utilization facilities, and a purpose of emergency power supply or autonomous power supply is achieved.

The invention provides a method for measuring difference-frequency wave space distribution characteristics in a parameter sound field. Firstly, the parameter sound field is composed of two lines of high-frequency sound waves f1 and f2, an active area of the parameter sound field is measured, the parameter sound field is uniformly divided into n measuring grids, a difference-frequency wave amplitude value is measured on any one grid point A, then a low-frequency sound wave f3 is independently emitted, and the amplitude value of the sound wave at the point A is equal to the difference-frequency wave amplitude value; finally, the three lines of sound waves f1, f2 and f3 are emitted simultaneously, a power spectrum is obtained, and the phase position of a difference-frequency wave at the point can be obtained according to the f1 initial phase position corresponding to the minimum value of the power spectrum; the steps are repeated to measure the difference-frequency wave amplitude of other points and phase position information. According to the method, the distribution characteristics of the difference-frequency wave amplitude and the phase positions in the parameter sound field are described simultaneously, the problem that a difference-frequency wave phase position changing rule in the underwater parameter sound field is difficult to describe in an existing experimental method and an engineering technology is resolved, and a basis is laid for analyzing the characteristic of the sound parameter field.

The invention provides an output adjustment method for sound energy obtained by sound wave interaction in a nonlinear medium. The output adjustment method comprises the following steps of: (a) performing nonlinear interaction on a pump wave with the frequency of w3 and a weak signal wave with the frequency of omega1, and generating a resonance wave with the frequency of omega2; (b) respectively calculating amplitude values B1(x), B2(x) and B3(x) of the three waves at the displacement x after interaction according to the frequencies omega3, omega1 and omega2 of the pump wave, the weak signal wave and the resonance wave; and (c) adjusting the output energy of the three waves according to the change characteristics of the amplitude values B1(x), B2(x) and B3(x) of the pump wave, the weak signal wave and the resonance wave. According to the output adjustment method, the energy of the generated sound wave is changed according to a pulse rule on the basis of a basic theory of interaction of sound waves in optics and hydroacoustics; therefore, the output energy of each wave can be adjusted according to actual requirements.

The invention relates to an ultrasonic flaw detection method which comprises the steps as follows: (I) selecting two transverse wave ultrasonic probes with K; (II) respectively connecting the two ultrasonic probes with an ultrasonic flaw detector, and measuring the practical K values and incidence points of the ultrasonic probes with a test block CSK-I A; (III) placing one ultrasonic probe in a test block CSK-III A, adjusting the maximal echo of a phi 1*6 hole with depth of 10 mm to be 80% of reference wave, detecting the holes with depths of 20 mm, 30 mm and 40 mm, connecting the points corresponding to the wave crests to obtain a phi 1*6 distance-amplitude curve, and then increasing by 9 db; (IV) carrying out the operation of the step (III) on the other one ultrasonic probe; (V) fixing the two ultrasonic probes in parallel at oppositely directions; and (VI) carrying out detection by adopting sawtooth type scanning within the range of 2*K*T mm on two sides of welded seam. The ultrasonic flaw detection method can detect the flaws at different directions at one time.

The invention relates to a structural concentration modal parameter recognition method based on Moret wavelet transformation. A wavelet amplitude curve and a wavelet phase curve are analyzed by using an improved modal parameter recognition method on the basis of the Moret wavelet transformation theory so that various orders of modal frequency and modal damping of a structure are calculated. According to the invention, criterions of civil engineering structure concentration modals are quantitatively defined, a method for determining structural frequency according to wavelet accumulating energy spectrum is provided, a wavelet center frequency optimizing algorithm is established, and the process of carrying out the damping ratio recognition on applied wavelet transformation is improved. On the basis, the invention provides a full set of flow of the structural concentration modal parameter recognition method based on the Moret wavelet transformation. The method has the advantages of improving the precision of wavelet transformation recognition structural modal parameters, effectively avoiding the influence caused by end effects, and overcoming the subjectivity, the experience and theblindness of selecting a wavelet transformation centre frequency and a wavelet amplitude fitting region, thereby being capable of being widely applied and popularized.

The invention relates to a continuous and nondestructive method for recognizing a layer structure in a tree, and can detect and image structures and abnormity in trees. Echo data are obtained at first by using radar waves to detect trees. When the radar waves are transmitted in wood, different dielectric constants in the wood affect radar wave transmitting speed, amplitude intensity, reflection time and the like. Dielectric constants of different dielectric layers (a bark, a splint wood and a heartwood) inside the tree are different, echo signal amplitude and reflection time of the radar waves are different. The dielectric constants of the various layers are estimated by a layer-by-layer inversion method, and electromagnetic wave transmitting speed is determined; and echo time delay of the various layers is obtained by a Hilbert detection method. Thicknesses of the various layers are determined on the basis of the echo time delay and the transmitting speed. According to the characteristics that a reflection wave amplitude value and value of difference between dielectric constants of adjacent interfaces are directly proportional, and reflection wave time delay depends on the property and the position of dielectric, the position and the shape of a rotten part in the tree can be determined by analyzing echo signal time delay and amplitude.

The invention discloses a device and a method for measuring the height of a micro-amplitude liquid surface wave in real time. The device comprises a laser, a transparent liquid tank, a photoelectric position sensor, a translation frame, a rocker, a screw, a slide rail, an oscilloscope and a fixed nut; the fixed nut is fixed on the slide rail; the screw is screwed with the fixed nut by screw threads; one end of the screw is sleeved with the translation frame arranged on the slide rail; the screw can rotate at the sleeving position and can drive the translation frame to translate; the other end of the screw is fixedly connected with the rocker; the top and the bottom of the translation frame are respectively provided with horizontally extended frame arms; the photoelectric position sensor and the laser are arranged on the inner lateral surfaces of the two frame arms in an up-and-down over-against manner; the signal output end of the photoelectric position sensor is connected with the oscilloscope. The device and the method are used for carrying out non-contact high-accuracy real-time measurement on the characteristics of the liquid surface wave, such as the wave amplitude and frequency of the micro-amplitude liquid surface wave, and solve the problem that in the prior art, a laser refraction method cannot accurately measure the wave amplitude of the micro-amplitude liquid surface wave.

The invention belongs to the field of nondestructive testing ultrasonic flaw detection, and discloses a method used for detecting welding quality of welding which is carried out in an intermediate layer connection manner. According to the method, ultrasonic longitudinal wave reflection type liquid immersion technology is adopted; a focus is focused on a connection interface, sensitivity is maintained unchanged; a scanning mechanism is moved along different axial directions on a detecting surface; echo wave amplitudes of the connection interface are observed; a welding complete zone with a lowest echo wave amplitude is found; sensitivity is adjusted to a value that the echo wave amplitude of the welding complete zone accounts for 45 to 55% of full screen amplitude; scanning on a whole workpiece is carried out with the sensitivity value; and calculation and evaluation on the workpiece are carried out based on a defect determination criterion, wherein according to the defect determination criterion, the echo wave amplitude of the connection interface is more than 80% of the full screen amplitude. No extra reference test piece is needed by the method; detection cost is reduced greatly; ultrasonic detection processes are simplified; detection time is saved; and detection efficiency is increased.

The invention provides an experimental measurement method for medium-high frequency acoustic performance of a large-pipe-diameter silencer. According to the experimental measurement method for the medium-high frequency acoustic performance of the large-pipe-diameter silencer, due to the fact that a hollow pipeline and a tail end silencer are arranged at the tail end of an experimental facility, wherein the hollow pipeline and the tail end silencer have different impedances, the boundary conditions can be changed, and an equation set representing the relation between the amplitude value of a front incident acoustic wave and the amplitude value of a front reflection acoustic wave of the silencer to be tested and an equation set representing the relation between the amplitude value of a rear incident acoustic wave and the amplitude value of a rear reflection acoustic wave of the silencer to be tested are set up. On the basis of the existing silencer transmission loss measurement principle and the experimental facility, an inlet-and-outlet measurement pipe section which is composed of two rigid concentric round pipes is designed, and due to the fact that the plane wave cut-off frequency of the annular pipe structure and the plane wave cut-off frequency of the inner pipe with the smaller diameter of the inlet-and-outlet measurement pipe section are much larger than the plane wave cut-off frequency of an inlet-and-outlet pipeline of an existing silencer, the measurement frequency range of the transmission loss of the large-pipe-diameter silencer is expanded. According to the experimental measurement method for the medium-high frequency acoustic performance of the large-pipe-diameter silencer, a non-reflection end does not need to be designed, and the medium-high frequency acoustic characteristics of the large-pipe-diameter silencer can be accurately measured.

The aim of the invention is to modify prior art converters for surface acoustic waves in such a way that, despite an essentially homogeneous amplitude profile, other weighting factors can also be realized as 0 or ±1. The invention considers converters of the prior art that consist of prong groups which are comprised of at least two prongs, are arranged on a piezoelectric substrate, and which are assembled to form collector electrodes. According to the invention at least some of the prong groups are constructed in such a way that they differ from the remaining prong groups with regard to the wave amplitude excited thereby. In order to fulfil the aim of the invention, a combination of the following features is provided: a) the prongs form, in their entirety, a structure which tapers in a prong direction, and; b) at least some of the prong groups (21; 23; 31; 33), designated as structured prong groups, are subdivided, in a prong direction, into a number of subconverters (231; 232; 331; 332) and these subconverters are electrically connected in series. The invention can be used in components which function on the basis of surface acoustic waves, for example, in broadband band-pass filters and in delay lines.

A simplified sine wave sampling circuit relates to the technical field of sampling circuits. The simplified sine wave sampling circuit comprises an inverting closed-loop amplifying circuit composed of an operational amplifier U1A, an input resistor RA and a feedback resistor RB. Specifically, the non-inverting input end of the operational amplifier U1A takes reference voltage, the inverting input end of the operational amplifier U1A is connected with the sampling end through the input resistor RA and connected with the amplification circuit output end through the feedback resistor RB, a divider resistor RC is connected between the amplification circuit output end and the ground, and a diode D1 is connected between the inverting input end of the operational amplifier U1A and the amplification circuit output end in series. Compared with the prior art, the sine wave sampling circuit is simplified, sine wave voltage can be reduced to a required range through a first-level operational amplifier, the circuit is simplified, positive half wave input and negative half wave input are both converted into positive voltage output, and amplitude range of voltage half wave output to analog to digital (AD) sampling port of a digital signal processor (DSP) is two times of that in the prior art, and sampling accuracy is improved by one time.