10 results about "Unipolar pulse" patented technology

The invention relates to the technical field of meteorological observation, in particular to a parameter measurement method and device based on a dual-band mode, equipment and a storage medium. Generating a dual-band excitation signal according to the aligned sine wave signal; analyzing the echo signal according to a preset gain coefficient, a time difference method and a preset attitude compensation formula to obtain a reconstructed quasi-unipolar pulse, an actual wind speed, a horizontal wind direction angle, a pitch angle, a three-dimensional wind speed vector, a roll angle and a real wind direction; acquiring real-time air pressure, and correcting a preset standard state sound velocity according to a preset sound velocity correction formula and the real-time air pressure to obtain a corrected sound velocity; according to the scheme, a dual-band signal attached to a medium is generated, after efficient transmission analysis, high-resolution pulses and multi-dimensional wind field parameters are obtained by means of gain, a time difference method, attitude compensation and the like, the sound velocity is corrected in combination with air pressure, comprehensive, accurate and rapid updating of data are considered, and the measurement reliability is improved.

The invention discloses a method for improving corrosion resistance of a pure aluminum surface in a NaCl solution, and relates to the technical field of high-current pulsed ion beams, an experiment is carried out on a TEMP-6 type HIPIB device, and a polymer anode unipolar pulse mode external magnetic insulation ion diode is adopted to generate 70% C and 30% H ion beams for an irradiation experiment; the ion beam parameters are as follows: the acceleration voltage is 300kV, the pulse width is 70-80ns, the beam density is 100A / cm < 2 >, the irradiation frequency is five times, and the background vacuum degree of a vacuum chamber during irradiation is 10 <-3 > Pa.

Aspects of this disclosure relate to driving a capacitive micromachined ultrasonic transducer (CMUT) with a pulse train of unipolar pulses. The CMUT may be electrically excited with a pulse train of unipolar pulses such that the CMUT operates in a continuous wave mode. In some embodiments, the CMUT may have a contoured electrode.

The application discloses a variable frequency motor rotating speed and direction measuring system and a measuring method. The measuring system comprises a driving power supply, a first sampling branch and a second sampling branch, the input ends of the first sampling branch and the second sampling branch are connected with a first phase power line and a second phase power line respectively, the first sampling branch and the second sampling branch comprise a current-voltage conversion unit, an amplification filtering unit and a square wave rectification unit connected in sequence respectively, the square wave rectification unit rectifies and outputs a unipolar pulse wave signal, a single-chip microcomputer collects a first pulse wave signal output by the first sampling branch and a second pulse wave signal output by the second sampling branch in a digital filtering mode by using an ADC mode, and obtains a first digital sequence and a second digital sequence, and the single-chip microcomputer obtains the rotating speed and direction of the variable frequency motor according to the first digital sequence and the second digital sequence. The application can directly use the electric signal of the driving power supply to measure the rotating speed and direction of the motor, and the environment is simple to construct and has good consistency.

The invention discloses an antenna switch based on a radio frequency transmission line and an avalanche diode and a control method of the antenna switch. An antenna comprises a signal source, the avalanche diode, a receiver and the radio frequency transmission line. The control method comprises the following steps: transmitting a unipolar pulse signal through a signal source to perform reverse breakdown conduction on a first avalanche diode, a second avalanche diode and a third avalanche diode, and transmitting the signal to an output end and a second radio frequency transmission line through a first radio frequency transmission line; the second radio frequency transmission line reflects the unipolar pulse signal, delays a preset time and transmits the unipolar pulse signal to the output end of the first radio frequency transmission line, and the output end forms a bipolar pulse waveform which is radiated outwards through the antenna. According to the invention, automatic switching of the antenna switch between transmitting and receiving can be realized without a peripheral control circuit. The antenna switch based on the radio frequency transmission line and the avalanche diode and the control method thereof can be widely applied to the technical field of transceiving antenna switch control.

The invention discloses a subnanosecond pulse source device with continuously adjustable width, and the device comprises a driving module which is used for carrying out the continuous time delay adjustment of one path of sine excitation signal distributed by a power divider through changing the voltage of a voltage-controlled phase shifter, and carrying out the continuous time delay adjustment of the other path of sine excitation signal distributed by the power divider through combining with the other path of sine excitation signal distributed by the power divider. A double-channel square wave signal with continuous and adjustable relative time delay is generated to drive a Gaussian pulse generator module; the Gaussian pulse generator module is used for generating two paths of subnanosecond negative pulse signals under the triggering of the two-channel square wave signals with continuously adjustable relative time delay, and the time interval continuously changes along with the time delay adjustment of the voltage-controlled phase shifter; the pulse synthesis and polarity selection module is used for performing polarity conversion on one sub-nanosecond negative pulse signal to obtain a positive pulse signal; performing power synthesis on the positive pulse signal and the other sub-nanosecond negative pulse signal to obtain a bipolar pulse; and a subnanosecond-level unipolar pulse signal with continuously adjustable width is obtained through detection.

The application relates to a method for operating an inverter that has an H4 bridge circuit having a first half-bridge and a second half-bridge for converting an input-side direct voltage into an output-side alternating voltage and is configured for supplying electrical power of a direct voltage source with a variable potential relative to a ground potential, for example, of a photovoltaic generator with a leakage capacitance with respect to ground, to an alternating voltage grid. The method includes unipolar pulse-width-modulated clocking for each of the two half-bridges for the half-wave generation of substantially sinusoidal half-bridge voltages, and modifying the clocking of the half-bridges in a transition region around a zero crossing of the output-side alternating voltage to damp a leakage current (IA) that flows through the leakage capacitor to ground. The application also relates to an inverter and to a computer program product.

The invention relates to the technical field of electric power engineering, discloses a cable fault identification method based on bipolar pulse square wave excitation, and solves the problems that in the prior art, when a cable fault point is identified, sine waves are used for excitation, the frequency is single, and detail changes are difficult to capture. The bipolar pulse square wave is used as the excitation signal, compared with sine wave and square wave signals, the bipolar pulse square wave has rich harmonic component characteristics, the high-frequency impedance characteristic of the shielding cable in the broadband range can be effectively obtained, and compared with unipolar pulse square waves, the bipolar pulse square wave has the advantage of being wider in harmonic distribution range. After the excitation signal is injected into the shielded cable, the response signal of the shielded cable is collected to obtain the real impedance spectrum, and the real impedance spectrum and the standard impedance spectrum generated based on the transmission line model are compared and analyzed to identify and position the fault point, so that the cable fault point can be identified in a wider frequency range; and detail change capture of the cable under excitation is realized.

This disclosure presents an active filtering method and apparatus for a single-phase inverter based on current slope control. The method includes: first, using unipolar pulse width modulation (PWM) technology, converting the DC power supply voltage through an L-type grid-connected single-phase bridge inverter to generate a PWM output voltage. During PWM generation, the relationship between factors affecting the slope change of the output current is analyzed to generate a current slope change law. Then, based on the current slope change law, an active filtering single-phase inverter is used to compensate for voltage changes across the inductor, ensuring control of the current slope during DC-DC conversion. This disclosure optimizes the filter inductor design at the cost of adding an additional bridge circuit, reducing the filter inductance value by 5 to 10 times. This achieves a significant reduction in filter size while maintaining unaffected harmonic suppression.

The invention discloses an ultrahigh-frequency ultrasonic transducer capable of generating quasi-unipolar pulses, and belongs to the technical field of ultrasonic transducers. The transducer comprises a backing layer, a high-frequency piezoelectric layer and a combined layer which are sequentially arranged from bottom to top. The combined layer comprises an acoustic decoupling layer, a first high-frequency matching layer, a second high-frequency matching layer, an ultrahigh-frequency piezoelectric layer, an ultrahigh-frequency polymer matching layer and an ultrahigh-frequency metal matching layer. A penetrating cavity is arranged between the first high-frequency matching layer and the second high-frequency matching layer, and an acoustic decoupling layer, an ultrahigh-frequency piezoelectric layer, an ultrahigh-frequency polymer matching layer and an ultrahigh-frequency metal matching layer are sequentially arranged in the penetrating cavity in a stacked mode. During working, the high-frequency piezoelectric layer and the ultrahigh-frequency piezoelectric layer can be driven to generate forward waves of high-frequency ultrasonic waves and ultrahigh-frequency ultrasonic waves respectively by reasonably adjusting electric excitation parameters, and the forward waves of the high-frequency ultrasonic waves and the ultrahigh-frequency ultrasonic waves are superposed, so that quasi-unipolar pulses with sharp main lobes and low side lobe levels are synthesized. The problem of pulse trailing of the ultrahigh frequency transducer is effectively solved, the axial resolution is remarkably improved, and meanwhile high detection sensitivity is kept.