112 results about "Response Amplitude" patented technology

A direct detector for terahertz radiation comprises a grating-gated field-effect transistor with one or more quantum wells that provide a two-dimensional electron gas in the channel region. The grating gate can be a split-grating gate having at least one finger that can be individually biased. Biasing an individual finger of the split-grating gate to near pinch-off greatly increases the detector's resonant response magnitude over prior QW FET detectors while maintaining frequency selectivity. The split-grating-gated QW FET shows a tunable resonant plasmon response to FIR radiation that makes possible an electrically sweepable spectrometer-on-a-chip with no moving mechanical optical parts. Further, the narrow spectral response and signal-to-noise are adequate for use of the split-grating-gated QW FET in a passive, multispectral terahertz imaging system. The detector can be operated in a photoconductive or a photovoltaic mode. Other embodiments include uniform front and back gates to independently vary the carrier densities in the channel region, a thinned substrate to increase bolometric responsivity, and a resistive shunt to connect the fingers of the grating gate in parallel and provide a uniform gate-channel voltage along the length of the channel to increase the responsivity and improve the spectral resolution.

The invention discloses a modal damping ratio rapid calculation method based on a pulse excitation response spectrum. The method comprises the following steps: firstly, determining excitation and vibration pick-up positions of a structure, wherein the excitation and vibration pick-up positions are on a node and a nodal line adjacent to a modal shape, and have remarkable responses under various test modal shapes; recording a vibration pick-up point response signal by a signal acquisition device, and performing discrete Fourier transform to obtain a response spectrum; extracting corresponding responses under a resonance (or peak) frequency an adjacent frequency thereof on the basis to obtain a stable response amplitude; and lastly, calculating relevant parameters such as a frequency ratio and a response ratio in order to realize identification of a modal damping ratio of the structure. Through adoption of the method, the technical problems that semi-power points are difficult to find accurately in a conventional semi-power method, a frequency response function needed for calculating the modal damping ratio cannot be acquired sometimes in a frequency domain method since certain excitation time domain signals are difficult to measure directly, and transient components are attenuated incompletely, operations are complicated and the like in response under contact type excitation in the prior art can be solved.

The invention discloses a force limit control vibration test system and a method utilizing the system for vibration test. The test system includes a vibration table, a force measuring device mounted at the upper part of the vibration table and used for placing a test piece, a vibration test control system and a data collecting and processing system, wherein the force measuring device includes an upper auxiliary tooling, a lower auxiliary tooling and a three-way force sensor arranged between the two auxiliary toolings; and the upper auxiliary tooling, the lower auxiliary tooling and the three-way force sensor are mechanically connected. In the method, as the signal-to-noise ratio of the force signal is higher than that of the acceleration signal, the precision of the force response amplitude limit satisfies 10% as required by GJB1027A, and is superior to the control precision of the conventional acceleration method.

The invention discloses an amplitude weighting-based ground penetrating radar back projection imaging method, which belongs to the field of radar imaging. The traditional back projection imaging method has the problem of insufficient clutter and noise suppression ability. According to the amplitude weighting-based ground penetrating radar back projection imaging method, as for any imaging point A, time delay is used for calculating a scattering response amplitude xA,k=rk(t), and t=tauA,k of the imaging point in each channel; a response amplitude corresponding to a point on hyperbolic echo is acquired through edge extraction to form a window function; weighting is carried out on the scattering response amplitude xA,k of each channel, and imaging on the A point is completed through coherent superposition; and all imaging points are traversed to complete the entire imaging process. The window function is used for carrying out weighting processing on the scattering amplitude, the target detection precision is improved, and the noise and clutter interference suppression ability is improved.

The invention relates to a road vanishing point detection method, in particular to a road vanishing point detection method based on video images, and belongs to the field of road detection. The problems that an existing detection method is high in error rate, a traditional voting algorithm is complex, most of time is consumed by the voting algorithm, and the calculation quantity is large when the multi-scale and multi-direction characteristics of Gabor wavelets are used for extracting textural features are solved. The road vanishing point detection method is characterized by including the steps that a frame of image data are input and converted into a gray level image, and fast Fourier transform is carried out; the textural response range is calculated based on a Gabor filter; the main direction of image textures is calculated; the number of votes of particles is calculated; the range of particle distribution is adjusted; a dynamic observation model for vanishing points is set up; particle filtering is performed, and the vanishing points are output. The road vanishing point detection method can be applied to computer vision systems including an autonomous navigation system of an intelligent walking robot or a pilotless automobile and the like.

A vibration change is detected by a touch signal probe having a vibrator (16) composed of a stylus support (10) and a stylus (13) attached thereto, and a vibrating/detecting means (12) provided to the stylus support (10) for applying vibration to the vibrator (16) and detecting a vibration condition changing when the stylus (13) touches a workpiece. The vibrator (16) is vibrated at a frequency equivalent to secondary intrinsic frequency (w2) to make resonance and the vibration change is detected by superposing a vibration component of primary intrinsic frequency (w1). Though the vibration at the secondary intrinsic frequency (w2) has high Q value, response amplitude is small. Accordingly, the vibration change is amplified by superposing the vibration component of the primary intrinsic frequency (w1).

The invention relates to the field of electronic devices, and discloses a humidity sensor, an electronic device and a respiration detection system and method. The humidity sensor is made of a sensitive thin film material sensitive to water vapor, response time can be greatly shortened, response amplitude is increased, several seconds to several minutes of the response time of a humidity sensor in the prior art are shortened below 0.1 second, the humidity (water vapor content) in environment gas can be measured, and real-time respiration monitoring is possible. Furthermore, the humidity sensor is adopted in the electronic device or the respiration detection system, the water vapor content in respiration can be monitored in real time, and therefore physical conditions are monitored and the guidance is provided for respiration exercise.

The invention relates to a servo system control method based on relay feedback, belonging to the technical field of motion control. The method comprises the following steps of: controlling a servo system for the first time by using a relay with an initial amplitude value to acquire a rotation rate after initial motion time; acquiring a relay amplitude value corresponding to the upper limit and the lower limit of the rotation rate according to the motion information of the first time, and respectively carrying out motion control on the servo system for the second time and the third time under the amplitude value through the relay in a time delay mode to acquire a stable response amplitude and a stable response cycle; identifying system model parameters and a dry friction magnitude according to the motion information of the second time and the third time; and carrying out optimization of control parameters and feedforward compensation of dry friction based on the identified parameters. The method of the invention can be used for quickly optimizing controller parameters and realizing effective compensation of friction, thereby improving the control accuracy of the servo system.

A transmitter using quadrature modulation includes a rectangular to polar converter for converting data symbols into a polar form, where each polar symbol has a magnitude signal and an angle signal. Digital phase modulation circuitry includes an all digital PLL circuit for generating a phase modulated RF carrier signal responsive to the angle signal frequency control word (FCW) and a carrier frequency FCW. A digitally controlled amplifier for amplifying the phase modulated signal is controlled by a digital amplitude control circuitry for controlling the gain of the digitally controlled amplifier responsive to the magnitude signal.

The invention relates to the field of digital signal processing, and discloses a method and a system for converting time domain signals into frequency domain signals. According to the method, the time domain signals are subjected to curve smoothening and are then regenerated into approximate simulation signals to be transmitted to a resonance system carrying out damped forced simple harmonic vibration, and in addition, the resonance intensity of the resonance system is calculated and is used as the intensity of the frequency domain signals. Any frequency point can be selected for calculation, so when only the signals of one special frequency point or several special frequency points need to be calculated, the calculation quantity is much lower than that of the traditional calculation method. Further, a time-frequency distribution diagram is obtained through calculating the frequency domain signal intensity change process, and the frequency domain signal intensity of the frequency point can be obtained through superimposing the frequency domain signal intensity at the corresponding moments of all sampling points of the corresponding frequency points, so the time domain signals are successfully converted into the frequency domain signals. The calculation is carried out on each sampling point one by one, so the time response can reach up to the sampling period, and in addition, the response amplitude is adjustable.

A spread spectrum communication system includes a channel encoder configured for modulating a carrier signal with data to form an information signal. A spreading sequence generator is configured for generating a spreading sequence having a phase angle dependent upon a chaotic sequence and contiguously distributed over a predetermined range. The chaotic sequence also has a magnitude which is selectively dependent upon the pseudo-random number or chaotic sequence. The invention also includes a multiplier configured for forming a spread spectrum signal by multiplying the information signal by the spreading sequence. The spreading sequence generator is responsive to a magnitude control signal for controlling the selective dependency of said magnitude. The magnitude can be constant to form a constant amplitude zero autocorrelation signal. Alternatively, the magnitude can be allowed to vary in selectively controlled chaotic or pseudo-random manner to vary a peak to average power ratio.

The invention provides a disturbance mixed injection impedance frequency sweep control method. A impedance frequency sweep control device related to the method comprises a disturbance mixed injectionunit and a disturbance control unit. By adopting the impedance sweep frequency control method, a primary disturbance signal with settable duration and amplitude can be injected through the disturbancemixed injection device. By comparing the ratio of the primary disturbance response amplitude to the fundamental wave amplitude in advance, a disturbance injection mode meeting the precision and the system stability is selected as secondary disturbance injection. The disturbance control unit is used to collect the response of the grid-connected equipment under the secondary disturbance, and calculate impedance of grid-connected equipment. The method is simple to realize, and can be used to effectively select the disturbance injection mode with high precision and small influence on the system stability. The impedance sweep frequency control device can be used to realize voltage and current disturbance injection. A basis is provided for impedance-based stability analysis.

A fiber gas sensor including a core fiber comprising at least one Bragg grating region, a fiber cladding in contact with the core fiber along an entire length of the core fiber, and a sensing matrix structure disposed upon the outer surface of the fiber cladding along a portion of the length of the fiber cladding and surrounding the fiber Bragg grating region. The sensing matrix structure comprising a bonding layer disposed on the outer surface of the fiber cladding layer, a nano-structured trampoline matrix layer disposed on the outer surface of the bonding layer and a capping layer disposed on the outer surface of the matrix layer. The thermally modulated response amplitude of the fiber gas sensor is found to linearly depend upon the gas molecular weight, and can be directly used to determine heat specific capacity ratio of Cp/Cv.

The invention provides a method for testing the vibration fatigue performance of metal in an axial resonance state. The method comprises steps: selecting a test piece, pasting a strain gauge, and measuring a response acceleration-strain/stress relationship of the test piece in a resonance state; in combination with the planned stress level, calculating the response acceleration of the test piece during formal test; carrying out the modal test on the test piece to obtain an inherent frequency point and a response amplitude ratio of axial vibration; setting the excitation frequency according tothe inherent frequency point, and calculating an excitation acceleration according to the response amplitude ratio measured by the test; finely adjusting a real-time excitation acceleration value in the test so that target response acceleration change is +/-2%; setting a resonance search and resonance residence program to keep the test piece in a resonance state in the test process, and stopping the test when the response acceleration of the test piece is suddenly reduced or the test piece is broken; and obtaining the cycles of the vibration system when the test is stopped. The method is advantaged in that the axial fatigue test is carried out on a metal material in a vibration mode, and the test period can be greatly shortened.

The invention relates to a phase modulation operation capability test method and system for wind turbine generators. The phase modulation operation capability for wind turbine generators includes a leading phase operation capability and a lagging phase operation capability. The test method can generate voltage disturbance by switching a dynamic reactive power compensator installed in a field station so as to test the response time and the response amplitude of each wind turbine generator with the phase modulation operation capability to voltage disturbance. The test system includes a voltage/current acquisition terminal and a data recording and analysis system based on Labview. The system can test the phase modulation operation situation of a plurality of wind turbine generators at the same time, and compares the motion time sequence and the motion amplitude for phase modulation operation for each wind turbine generator, and then automatically generates a test report. The phase modulation operation capability test method and system for wind turbine generators has the advantages of being high in test efficiency and being high in test accuracy, and can greatly promote popularization of phase modulation operation for wind turbine generators and improve the reactive adjusting capability of a wind power station.

Disclosed is a beam overlap verification system and method for phased array ultrasonic inspection. A scan plan for the ultrasonic inspection defines a suitable probe, wedge and calibration block having machined defects for the geometry to be inspected, and makes a beam definition which defines a set of ultrasonic beams emitted by the phased array. An intersection amplitude unit records the response amplitudes from each defect at predetermined intersection points of adjacent beam pairs as the probe and wedge are manually scanned across the calibration block. An overlap verification module determines the −6 dB overlap of all adjacent beam pairs which are relevant to the geometry to be inspected, and verifies that the beam overlap conforms to the required coverage according to the ASME or other relevant codes. In this way, coverage is experimentally verified during calibration prior to inspection of a known geometry, such as a weld.

A system and method are disclosed for calibrating non-linear behavior using attenuated stimuli and responses which allows for calibration with unknown stimulus and less expensive sources and receivers. The device under test is stimulated with a signal and then an attenuated version of the same signal, so that non-linear differences between responses can be attributed to the device rather than the signal source. Alternatively, or in conjunction with attenuation of the stimulus, the output of the device at different response amplitudes can be selectively attenuated such that the receiver measures approximately the same amplitude. This allows non-linear differences between measurements to be attributed to the device rather than the receiver. Two or more different signal sources can also be used, where responses are measured for each signal individually and then for at least one linear combination of signals.

The invention discloses a Buck-Boost circuit fault feature extraction method under variable conditions, comprising: first, obtaining two frequency domain characteristics of a Buck-Boost circuit; and secondly, obtaining a circuit state monitoring signal, utilizing discrete dyadic wavelet transform to obtain circuit frequency domain response amplitude frequency characteristics, and based on obtained amplitude frequency characteristics, utilizing a cat-swarm algorithm to identify parameters of each component, and using circuit component parameter values as fault characteristic parameters. The method does not relate to external parameters, thereby realizing Buck-Boost circuit fault feature extraction under variable conditions.

The invention provides an estimating method and the device for wireless channel in orthogonal frequency division multiplexing communication system. It judges if the OFDM symbol at reception end is front series or not, if it is front series, the method carries on the LS estimation based on front series; then selects key paths, (a) compares the channel impulsion response coefficient amplitude and the preset threshold, and selects an element of channel impulsion response which is not less than the threshold as the key path, the other transmission paths are abandoned, or (b) selects the element which is preset in quantity and has the maximal channel impulsion response amplitude as the key transmission path, abandons other paths; if it is not front series, it is OFDM data symbol, and carries on LS estimation based on guiding frequency in OFDM symbol to the selected transmission path. The obtained amplitude value and phase are the terminal channel estimation value.