59 results about "Harmonic method" patented technology

The invention provides a method for regulating and controlling continuous generation of ultraviolet precise spectrums, having the characteristics that the chirp contents of single beam few-cycle pulses are regulated to generate ultraviolet precise spectrums in the forms of discrete spectrums, continuous spectrums, even-order spectrums and interference spectrums continuously during a higher harmonic method is used to generate ultraviolet precise spectrums; on the basis of stable generation of any form of ultraviolet precise spectrums, a second beam of few-cycle femtosecond light source are introduced to form a two-tone few-cycle femtosecond laser pulses; and the intensity, the chips, the polarization and the pulse width of the second beam of light source are changed and a beam combining piece is used to regulate the relative angles among lights in a two-tone field, thus realizing the real-time and multi-dimensional regulation and control on each form of selected ultraviolet precise spectrums. The method is simple and easy to operate and can be utilized to realize the multi-dimensional precise regulation and control.

The invention discloses a linear frequency modulation multi-beam laser heterodyne second harmonic method based glass thickness measuring device and method and belongs to the technical field of optical measurement. The linear frequency modulation multi-beam laser heterodyne second harmonic method based glass thickness measuring device and method aims at solving the problem that the measuring result is large in error due to the fact that only single to-be-measured parameter values are obtained through the existing glass thickness measuring method. The linear frequency modulation multi-beam laser heterodyne second harmonic method based glass thickness measuring device comprises to-be-measured sheet glass, a linear frequency modulation laser, a first planar mirror, a second planar mirror, a convergent lens, a photoelectric detector and a signal processing system. The linear frequency modulation multi-beam laser heterodyne second harmonic method glass thickness measuring method comprises opening the linear frequency modulation laser, enabling the linear frequency modulation laser to emit linearly polarized light, enabling the photoelectric detector to receive light beam signals and a DSP (Digital Signal Processor) to continuously collect electric signals output from the photoelectric detector and process collected difference frequency signals and obtaining the thickness of the to-be-measured sheet glass according to the relationship between the frequency and the thickness. The linear frequency modulation multi-beam laser heterodyne second harmonic method based glass thickness measuring device and method is used for measuring the glass thickness.

The invention discloses a method for measuring micro-impulse based on a multi-beam laser heterodyne second harmonic method and a torsion pendulum method, relates to a micro-impulse measurement method, and solves the problem of low measurement accuracy caused by poor effect of acquiring a laser difference frequency signal and low operation speed of signal processing in the conventional method for measuring the micro-impulse by using the multi-beam laser heterodyne second harmonic method. The multi-beam laser heterodyne second harmonic method is applicable to the micro-impulse measurement method; the measurement of the micro-impulse is converted into the measurement of a pendulum angle of torsion pendulum, and the size of the micro-impulse is obtained by directly measuring the pendulum angle of the torsion pendulum by using the multi-beam laser heterodyne second harmonic method, so measurement accuracy is effectively improved; when a rotating angle is smaller than 5 DEG, the measured micro-impulse has a linear relation with an incident angle, and a measurement error is smaller than 0.5 percent; requirements for measurement of the impulse of a laser micro-thruster can be met; and good measurement means can be provided for evaluation of the performance of the laser micro-thruster.

The invention provides a device and method for measuring micro impulse by means of a linear frequency modulation multi-beam laser heterodyne quadratic harmonic method and a torsional pendulum method, and belongs to the field of optics. The device and method are aimed to solve the problems that according to an existing laser interference method for measuring the micro impulse, accidental errors are large and measurement precision is low. Linearly polarized light emitted from a linear frequency modulation laser device is reflected through a first plane reflection mirror and a second plane reflection mirror and then enters a plane standard lens, light beams penetrating through the front surface of the plane standard lens are reflected by the rear surface and the front surface of the plane standard lens in the plane standard mirror for many times, then multiple beams of reflection light are obtained, the beams of reflection light penetrate through the front surface of the plane standard lens, then the beams of the reflection light and the light beams reflected through the front surface of the plane standard lens penetrate through a vacuum window and are converged to a photosensitive face of a photoelectric detector outside a vacuum chamber through a convergence lens, the photoelectric detector outputs electric signals to a signal processing system, and the signal processing system obtains the micro impulse borne by a standard beam according to the electric signals received continuously. The device and method are suitable for measuring the micro impulse.

The invention relates to a method and device for extracting and using a secondary side harmonic wave of a distribution transformer, and belongs to the technical field of power. The method comprises the steps: harmonic monitoring and analysis, harmonic separation and extraction, and harmonic recycling; the analysis and processing of a harmonic wave are carried out in a power distribution network at the step of harmonic monitoring and analysis, so that a technician adjusts related parameters. The step of harmonic separation and extraction comprises two steps: separation and extraction. The resonance filtering principle of a passive power filter is employed in the step of separation, so as to separate a characteristic subharmonic from a power circuit; the coupling principle of a mutual induction coil is employed for the step of extraction, so as to lead a harmonic current to a subsequent circuit for extraction. The harmonic current is converted into DC electric energy for storage at the step of harmonic recycling, thereby achieving the recycling of the harmonic electric energy. According to the invention, the method and device enable the harmonic electric energy to be separated, extracted and stored, can reduce the impact on a power grid from harmonic, improve the quality of electric energy, achieve the complete use of the electric energy, and are of great significance to the energy-saving and loss-reducing research.

The invention relates to a voltage feed-forward control method suitable for parallel connection of a plurality of stationary synchronous compensators. The method includes the following steps of (1) determination of number of the stationary synchronous compensators: the number N of the stationary synchronous compensators in operation is determined by detecting the reactive component Iq of a system; (2) net-side impedance detection: the net-side impedance Zg is detected by means of an active injection harmonic method; and (3) feed-forward signal generation: the final feed-forward voltage Uff of the stationary synchronous compensators is obtained based on the net-side impedance Zg detected in the step (2), compensation point voltage Upcc, and current Ipcc. Compared with the prior art, the voltage feed-forward control method has the advantages of wide application, good robustness, and low loss.

The invention discloses a method for measuring the incident angle of laser by a multi-beam laser heterodyne quadratic harmonic method, relating to a device and method for measuring an incident angle of laser, and solving the problem of relative low measurement precision due to poor laser difference frequency signal quality and low signal treatment computing speed when a multi-beam laser heterodyne method is adopted for measuring the incident angle of laser at present. In the invention, a vibration mirror is added on an optical path, and the vibration mirror does uniformly accelerated motion to carry out frequency modulation on light incoming to the front surface of the vibration mirror at different moments, and angle information to be tested is loaded to frequency difference of quadratic harmonics of heterodyne signals, thereby further obtaining the incident angle information of the laser. The invention is suitable for measuring the incident angle of laser.

The invention discloses a method and system for evaluating early loosening of a composite material bolt connection structure, including: obtaining the second-order nonlinear coefficient and sideband nonlinear coefficient of the ultrasonic response of the composite material bolt connection structure; building a nonlinear ultrasonic monitoring system to determine the optimum Optimum response frequency and acoustic modulation signal parameters; carry out nonlinear ultrasonic testing experiments on bolted joint structures in different pre-tightening states, and obtain high-frequency response signals of one sending and one receiving and acoustic modulation response signals of two sending and one receiving respectively; The processing and analysis are carried out to obtain the variation rules of the above two parameters under different pretension states of the bolts, and a regression model based on machine learning algorithms is constructed; based on the model, the early loosening of the composite bolted connection structure is evaluated. The invention combines the two nonlinear ultrasonic detection methods of the harmonic wave method and the acoustic modulation technology, and has a more remarkable and accurate monitoring effect on the early state of bolt loosening.