53results about How to "Avoid nonlinearity" patented technology

A sensor module (1) for measuring the distance to a target and / or the velocity of the target (50), the sensor module (1) comprising at least one laser source (100), at least one detector (200) being adapted to detect modulated laser light and at least one control element the control element (400) being adapted to vary the focus point of the laser light and / or the intensity of the laser light and / or the direction of the laser light. The control of the laser light emitted by the laser source (100) either by active optical devices as variable focus lenses or controllable attenuators or passive optical elements in combination with arrays of laser sources (100) and detectors (200) enable flexible and robust sensor modules.

The invention discloses a method for measuring an electro-optic phase modulator modulation factor, and relates to the technical field of the photoelectronic technique. In order to solve the problems that phase modulation signals cannot be directly detected on a photoelectric detector and nonlinearity cannot be omitted in PM-IM and FM-IM conversion processes, an optical fiber interferometer is adopted as a measuring device and composed of a beam splitter, an electro-optic phase modulator to be measured, an acousto-optic frequency shifter, an auxiliary electro-optic phase modulator and a beam combiner, wherein the electro-optic phase modulator to be measured is arranged on one interference arm of the optical fiber interferometer, the acousto-optic frequency shifter and the auxiliary electro-optic phase modulator are placed on the other interference arm of the optical fiber interferometer, and sinusoidal signals with different frequencies are loaded to the electro-optic phase modulator to be measured, the acousto-optic frequency shifter and the auxiliary electro-optic phase modulator respectively. Frequency response of the photoelectric detector is eliminated by setting a frequency relation of the loaded sinusoidal signals, self-calibration measurement is achieved, measuring accuracy of the electro-optic phase modulator modulation factor is improved, and the method has good application value.

The invention relates to a measuring method and system for d31 piezoelectric constant that adopts quasi-static method to testing d21 piezoelectric. The system is made up of energizing equipment and circuit equipment. The energizing equipment supplies acting force to testing sample by special stressing accessory. Circuit equipment supplies electric driving signal and taking amplifying and processing to low frequency alternating voltage signal, and display d31 piezoelectric constant. It has the advantages of easy to operate, rapid and accurate.

An apparatus and method are described for combining optical amplification and dispersion compensation in a Raman amplifier. A Dispersion-Managing Raman Amplifier (DMRA) combines Raman amplification with dispersion compensation by selecting the length and dispersion of the gain fiber to balance the dispersion of the link. This gain fiber is also single-mode at the signal and pump wavelengths. The pumping level is adjusted to balance the losses from the gain fiber and transmission link, while the pumping configuration is selected to remain within the 3 dB loss length for the pumping light. When the amplifier is split into two segments, the two segments may be joined by an isolator, a gain equalization element, and / or an optical add / drop multiplexer. For WDM transmission systems based on dispersion-shifted fiber (DSF), operation in the “violet band” between 1430–1530 nm is based on Raman amplification. By using a DMRA, a dispersion and nonlinearity managed system can be implemented. In particular, 4WM does not phase match in such a system, and modulation instability is absent in the transmission link. Furthermore, gain equalization can be added to the DMRA by cascading one or two Mach-Zehnder frequency filters. The invention also includes a method for symmetrically adding channels below and above the C-band, the gain tilt within the C-band can be minimized. Therefore, a roughly equal number of channels should be placed in the short-wavelength S-band and the long-wavelength L-band to minimize the Raman energy exchange in the C-band. Also, whereas C- and L-bands can be amplified using erbium-doped fiber amplifiers, the S-band can use either discrete or distributed Raman amplifiers. To minimize the interaction between pumps for different bands, alternate band pumps can be spatially dispersed and / or cross-polarized. The distributed Raman amplification can be achieved by pumping the transmission line with discrete laser diodes or by a Raman oscillator.

The invention provides a signal to noise ratio improving device and method for chirped pulse laser. The signal to noise ratio improving device and method for the chirped pulse laser solves the technical problems that an existing signal to noise ratio improving device for ultrashort pulse is low in transformation efficiency, parameters are hard to control, noise under ns and even ps cannot be restrained effectively, and cost is high are solved. A pockels cell and a specially designed n-level full-wave plate are inserted into one path in a Mach-Zehnder structured light path, a half wave plate is inserted into another path, and the pockels cell is driven to carry out scanning and filtering by adopting a conductive switch. The signal to noise ratio improving device and method for the chirped pulse laser have the advantages that conversion efficiency is high, the signal to noise ratio improving device can be used in a cascade connection mode, and an unnecessary nonlinearity function is avoided at the same time.

The invention discloses a permanent magnet synchronous motor low-speed domain rotor position identification method, so as to solve the problems that the traditional pulse signal injection method usesmultiple filters, the hysteresis effects are superimposed, the dynamic performance of the system is reduced, and the position estimation error is increased. A new low-speed position sensorless controlstrategy is proposed. In particular, on the basis of injection of a high-frequency pulse square wave voltage signal to a two-phase stationary coordinate system, through a generalized second-order integrator (SOGI), current in a beta axis is subjected to signal separation and amplitude demodulation, two paths of orthogonal signals including rotor position information are obtained, and through heterodyne and a rotor position observer, the rotor position information is extracted, and no filter is used during the whole signal demodulation process. The dynamic performance of the control system andthe accuracy of the rotor position estimation are effectively improved.

Apparatus for determining a utilized transmission capacity of a base transceiver station for transmitting a transmit signal, having a receiver, with which the transmit signal is receivable, and a detector for checking a number of utilizable transmit channels from the transmit signal for utilization thereof. The apparatus further includes a calculating unit for calculating the utilized transmission capacity based on a result of the check.

The invention discloses a quick initial alignment method for a moving base of an SINS (strapdown inertial navigation system) based on lie group description. The method comprises the following steps: replacing traditional quaternion description with lie group description to realize calculation of SINS attitude transformation; establishing a linear initial alignment model by using a lie group differential equation; establishing an augmented initial alignment model by taking gyroscopic drift as an augmented state quantity; and then realizing synchronous estimation of an initial attitude matrix and gyroscope constant drift by adopting a matrix-form Kalman filtering algorithm. According to the quick initial alignment method, the gyroscope constant drift is taken as the augmented quantity, and compared with a traditional initial alignment model, a more accurate augmented linear alignment model is established. The alignment method disclosed by the invention can realize one-step direct alignment of the SINS, greatly shortens the alignment time, is convenient for compensating errors in a strapdown resolving process, effectively improves the alignment precision, and is more suitable for practical engineering application.

The invention provides a prediction method for high-cycle fatigue life of a single crystal air film hole member, and relates to the technical field of porous mediums. The method comprises the steps ofdetermining a dangerous path according to a hole distribution mode of the single crystal air film hole member; building a crystal plasticity theory model, and inputting related parameters of the crystal plasticity theory model to a finite element model; outputting stress distribution of the dangerous path through the finite element model, and obtaining a maximum main stress amplitude and a maximum resolved shear stress amplitude on the dangerous path; and building a critical distance model, determining parameters of the critical distance model according to the maximum main stress amplitude and the maximum resolved shear stress amplitude, and performing calculation by an iterative program to obtain the high-cycle fatigue life of the single crystal air film hole member. According to the method, anisotropic material properties of single crystal and a deformation mechanism of crystal slip are considered; the difficult problem of high-cycle fatigue damage nonlinearity is solved; and a prediction result is small in dispersity and high in precision.

The invention provides a sigma-delta PLL frequency measuring circuit and method. The circuit comprises a rectifying circuit, a phase discriminator, a loop filter, an ADC and a delay link which are sequentially arranged from the input end. The output end of the delay link is fed back and input to the phase discriminator through a counter. The frequency measuring method comprises the steps that after the rectifying circuit filters and amplifies a signal to be detected, the signal to be detected is converted into a square signal with the frequency same as that of the signal to be detected; the phase discriminator measures the zero crossing point time difference of the square signal and an output signal of the counter, and a pulse current signal with the output area and the time in a direct proportion; after the integration and the filtering are carried out on an output current of the phase discriminator through the loop filter, the output current is converted into a voltage signal; the ADC converts analog voltage output by the loop filter into a digital signal; the delay link delays the digital signal output by the ADC, and therefore the frequency of the signal to be detected is determined; a counter output signal with the clock period and the delayed digital signal in a direct proportion is generated by the counter, and is output to the phase discriminator. The anti-noise capacity is strong in the process of measuring the frequency, the resolution ratio is high, and the frequency measurement can be achieved easily.

The invention provides a large-flow high-stability Mach number wind tunnel rapid adjusting system and method based on a temporary charging air source. The large-flow high-stability Mach number wind tunnel rapid adjusting system structurally comprises a temporary charging air source, a main valve, an auxiliary valve, a spraying pipe, a pressure sensor, a Mach number sensor and a control unit, and the auxiliary valve has the faster small-flow adjusting capacity and is connected with the main valve in parallel. The method comprises the following steps: (1) on the basis of 50% opening degree of an auxiliary valve, carrying out main valve manual adjustment on a characteristic Mach number point in a wind tunnel capability range to obtain a main valve opening degree and air source pressure relation curve cluster under a corresponding Mach number; (2) according to the instruction Mach number and the current air source pressure, obtaining the opening degree of a main valve through two-dimensional linear interpolation; and (3) carrying out closed-loop PID adjustment of the instruction Mach number by using the auxiliary valve, and maintaining the outlet Mach number. According to the invention, a composite control strategy of main valve feedforward and auxiliary valve closed-loop PID is adopted, and the problem that an outlet Mach number is not easy to stabilize due to continuous decrease of gas source pressure, poor repeatability of a main valve, strong nonlinearity and slow adjusting speed in a wind tunnel test is solved.

The invention discloses a strapdown inertial navigation system (SINS) swinging base self-aligning method based on Lie group optimal estimation. Lie group description is adopted instead of traditionalquaternion description to realize the calculation of SINS attitude transformation; a linear initial self-aligning filtering model based on the Lie group description is established by using a Lie groupdifferential equation; and a Lie group optimal estimation method is designed to determine an initial attitude matrix required by navigation. According to the method, the optimal estimation is directly performed on the initial attitude matrix by a Lie group optimal estimation algorithm, so that the initial attitude estimation problem is transformed into the optimal estimation problem of a SO(3) group; one-step direct self-alignment of the SINS is realized; the aligning time is shortened greatly; the problems of non-uniqueness and non-linearity generated by the traditional quaternion description of the initial attitude matrix are solved; the alignment accuracy is improved effectively; and the problem that the orthogonality of a rotation matrix cannot be ensured due to the additivity error and the calculation error in a Lie group filtering method is solved. The method has practical value in the practical engineering.

An experimental setup for bridge deck large-amplitude vertical-torsional coupled free vibration in wind tunnel test, which belongs to the technical field of wind tunnel test apparatus. The experimental setup includes the rigid model, the rigid circular rods, the lightweight rigid circular sprockets, the chains, the linear tensile vertical springs, the bearings, the sliders, and the guides. For the new setup, large-amplitude vertical-torsional coupled free vibration of a rigid deck model that failed in conventional testing device can be adapted by the vertical deformation of the springs without any lateral tilt. As a result, the possible nonlinear mechanical stiffness due to the springs tilt in conventional testing device is excluded. In addition, owing to the low rolling friction and damping between the sprockets and the chains, the mechanical damping ratio of the system are quite low and stable for very large-amplitude vibrations.

Disclosed is a bi-directional optical-amplifier module including first through fourth optical amplifiers, a mid-stage device for performing a desired signal processing for an upward or downward optical signal passing therethrough, a first optical-signal-path-setting device for supplying an optical signal inputted to a first input / output terminal of the bi-directional optical-amplifier module while outputting an optical signal outputted from the fourth optical amplifier to the first input / output terminal, a second optical-signal-path-setting device for supplying an optical signal inputted to a second input / output terminal of the bi-directional optical-amplifier module while outputting an optical signal outputted from the third optical amplifier to the second input / output terminal, a third optical-signal-path-setting device for outputting an optical signal outputted from the first optical amplifier to a first input / output terminal of the mid-stage device while supplying an optical signal outputted from the first input / output terminal of the mid-stage device to the fourth optical amplifier, and a fourth optical-signal-path-setting device for outputting an optical signal outputted from the second optical amplifier to a second input / output terminal of the mid-stage device while supplying an optical signal outputted from the second input / output terminal of the mid-stage device to the third optical amplifier.

A multi-stage optical amplifier that has an optical fiber with a first length of amplifier fiber and a second length of amplifier fiber. The optical fiber is configured to be coupled to a signal source that produces at least a signal wavelength λs and a pump source that produces a pump wavelength λp. Pump wavelength λp is less than signal wavelength λs. Signal input, signal output and pump input ports are each coupled to the optical fiber. A first lossy member is coupled to the optical fiber and positioned between the first and second lengths of amplifier fiber. A pump shunt is coupled to the signal input port and the signal output port.

The invention discloses a polarization four-step phase shifting method for digital speckle interferometry. According to the polarization four-step phase shifting method for digital speckle interferometry, polarization beam splitting prisms, a beam expander, quarter wave plates and polarizers are adopted to establish a polarization four-step phase shifting optical path; in a phase shifting process,two polarizers are rotated, so that 0-degree, 90-degree, 180-degree and 270-degree four-step phase shifting can be realized, and corresponding speckle images are acquired; and a random phase field atan initial moment is restored through a four-step phase shifting algorithm. Compared with a traditional time phase shifting method, the method replaces piezoelectric ceramics with two rotatable polarizers, and therefore, the hysteresis, nonlinearity and creep interference of the piezoelectric ceramics can be avoided, stable speckle images can be acquired, and accurate random phase extraction canbe realized.

The invention discloses a low-voltage compensation device and method of an energy-saving power distribution network. The device is divided into a rectification part, an inversion part and a bypass unit, wherein the rectification part comprises a relay QF1, a filtering capacitor C1, an AC reactor L1, an IGBT tube G1, a rectification diode and a photovoltaic cell panel, the inversion part comprisesa relay QF2, an IGBT tube G2, an IGBT tube G3, an inversion inductor L2 and a filtering capacitor C2, and the bypass unit comprises a bidirectional thyristor SCR. With the adoption of a series voltagecompensation mode, the problem of low voltage of the power distribution network is solved, and the device only needs to provide a part of load power; with the adoption of a transformerless DC seriesmode, the problems of loss and non-linearity of the transformer are prevented; combined with photovoltaic power generation, a working mode is switched, and the problem of extremely low voltage of a plurality of voltage regulation devices simultaneously running at access points is solved; and meanwhile, photovoltaic power generation is fully utilized, the effect of energy saving and emission reduction is achieved.

A pulse-wave measurement apparatus includes a pressure detecting capacitor which changes its capacitance according to the pressure within an artery; an operational amplifier which is connected at its inverting input terminal to one end of the pressure detecting capacitor and also is connected at its non-inverting input terminal to a reference voltage; a charge transfer capacitor; a switch which is connected to the inverting input terminal of the operational amplifier; and a voltage setting portion which is connected to the switch and to the output of the operational amplifier. The voltage setting portion is adapted to connect the other end of the switch to the output of the operational amplifier or to disconnect the other end of the switch from the output of the operational amplifier and applies a predetermined voltage to the other end of the switch.

The invention discloses a water level detection system with a pressure compensation function. The water level detection system comprises a detecting end and a data processing terminal connected with the same. The detecting end comprises a first control module, a signal collection module and a data transmission module, wherein the signal collection module and the data transmission module are connected with the first control module. The data processing terminal comprises a second control module, a key input module, a pressure compensation module, an alarm module and a display module, wherein the key input module, the pressure compensation module, the alarm module and the display module are connected with the second control module. The second control module comprises a computing unit, a parameter comparison unit and a control unit.

The invention discloses an SINS strapdown inertial navigation system shaking base self-alignment method based on Lie group optimal estimation, which adopts Lie group description to replace traditionalquaternion description to realize calculation of SINS attitude transformation, and utilizes a Lie group differential equation to establish a linear initial alignment filtering model based on the Liegroup description. And performing equivalent transformation on the state-related error by utilizing the left multiplication invariance of the plum group and the exponential mapping between the plum group and the plum algebra, establishing an equivalent state-independent plum algebra filtering equation, and estimating the initial attitude through the equivalent equation. According to the method, the state-dependent noise under the Lie group model is equivalent to the state-independent noise under the Lie algebra, compared with a traditional Lie group model, a more accurate Lie group linear alignment model is established, and the problems of non-uniqueness and nonlinearity caused by the fact that a traditional quaternion describes an initial attitude matrix are avoided. The method greatly shortens the alignment time, effectively improves the alignment precision, and is more suitable for practical engineering application.

An LAMOST astronomical telescope focal panel movement realizing mechanism is characterized in that a rotary movement mechanism, a tilted movement mechanism and a focusing movement mechanism are set as a co-movement mechanism, wherein, a large gear and a circular guide rail are fixedly connected on a base; six matched slide blocks are distributed on the circular guide rail; the slide blocks are connected with pinions through connecting plates; each pinion is meshed with the large gear; a drive motor is arranged on a shaft; the slide blocks are respectively connected with supporting rods through left single rod joint bearings; each supporting rod is connected on a focal panel through a right single rod joint bearing; every two supporting rods are arranged as one group in a V-shaped form, and one end of each of the two supporting rods leans against the connecting points of the focal panel through the right single rod joint bearings; three groups of connecting points are distributed in the same circle on the focal panel by 120 degrees; and the other end of each of the two supporting rods has a certain distance through the locations of the two slide blocks connected with the left single rod joint bearing on the circular guide rail. The invention not only simplifies the mechanical structure and the control system, but also improves the stability of the system.

The invention discloses a micro-motion platform for improving the resolution of a linear motor based on a flexible inclined beam. The micro-motion platform is provided with a base, six inclined beam components, two transition plates, an input plate, an output plate and two guide beam components. An output rod is mounted on the output plate of the micro-motion platform, and an output shaft of the linear motor is connected with the input plate of the micro-motion platform so as to apply the drive force to the micro-motion platform. The micro-motion platform disclosed by the invention has the functions of a two-level speed reducer in the same plane, improves the resolution of the linear motor by use of the motion reducing principle, and overcomes the shortcoming of lower resolution of the linear motor.

The invention provides a film bulk acoustic resonator, a filter and a preparation method of the film bulk acoustic resonator, belongs to the technical field of electronic manufacturing, and can at least partially solve the problems that an existing resonant filter has certain limitation in power bearing capacity, when the input power is increased, heat dissipation of a device is limited, the temperature of the device rises, the frequency of the device drifts, nonlinearity is generated, and the performance of the device is affected. According to the invention, SiC is used as a substrate material; the electrodes of the resonator are connected with the SiC substrate, and heat caused by high input power is dissipated in time by utilizing high thermal conductivity of the SiC substrate, so thattemperature rise of the device is avoided, the problems of frequency drift and nonlinearity of the device caused by temperature rise of the device are further avoided, and the performance of the device is improved.

The invention provides a novel real scene three-dimensional color data acquisition and display method. The novel real scene three-dimensional color data acquisition and display method utilizes a high-speed out-of-focus projector for projecting stripes to the surface of a measured object, and performs out-of-focus operation on a high-speed out-of-focus projector projection pattern; the out-of-focusprojection pattern is a binary image; a high-speed color video camera is used for receiving a synchronous signal of the high-speed defocusing projector, acquiring a deformed stripe image subjected toobject surface topography modulation and transmitting acquired data to a computer for data acquisition and processing; the computer processes an image shot by means of the video camera, solves the phase of stripes in a shot image, calibrates the whole measuring system to obtain a corresponding relation between pixel points on the video camera and pixel points on the projector is obtained, color textures and three-dimensional data of the object are obtained by adopting a decoding algorithm, and the color textures and the three-dimensional data are transmitted to a computer in a display instrument by means of a network.

The invention discloses a steel plate inner surface defect identification method based on fractional order wavelet transform, which is used for improving the detection accuracy of the shape and depth of the steel plate inner surface defect by using a signal processing method. The method comprises the following steps: collecting and storing an ultrasonic detection signal of the steel plate inner surface defect through a related sensor; performing fractional order Fourier transform on the obtained related signals, searching an optimal fitness value through a chicken flock algorithm by using an inter-class and intra-class distance ratio as a fitness function so as to realize optimal order selection of the fractional order Fourier transform, and then performing wavelet transform on the processed signals; taking the energy ratio of each component obtained by decomposition as a feature vector matrix, and testing a test sample set by using a random forest classification model, and the result shows that the shape and depth of the steel plate inner surface defect can be effectively identified.

The invention discloses a water level detection system for supplying power based on a voltage-stabilized source. The water level detection system comprises a detection end and a data processing terminal connected with the detecting end. The detecting end comprises a first control module, a signal acquisition module and a data transmission module. The signal acquisition module and the data transmission module are connected with the first control module. The data processing terminal comprises a second control module, a pressure compensation module, a display module and a voltage-stabilized source circuit. The pressure compensation module, the display module and the voltage-stabilized source circuit are connected with the second control module. The voltage-stabilized source circuit provides electric energy required for the second control module, the pressure compensation module and the display module.