236 results about "Radiofrequency pulse" patented technology

The invention discloses a radio frequency on-chip test system and a radio frequency on-chip test method. The radio frequency on-chip test system comprises a probe temperature adjusting module, an instantaneous pulse acquisition module, a dynamic compensation module, a thermal isolation module, radio frequency measurement equipment and a bearing platform. Wherein the probe temperature adjusting module is used for independently adjusting the temperature of a probe to a target value; the instantaneous pulse acquisition module is used for transmitting a radio frequency pulse signal and acquiring a radio frequency parameter when the probe is in contact with the normal temperature calibration sheet; the dynamic compensation module dynamically corrects the radio frequency parameters based on the real-time temperature of the probe; the thermal isolation module is used for reducing heat exchange between the probe and the external environment; the radio frequency measuring equipment is used for collecting and analyzing the radio frequency parameters; the bearing platform is used for bearing the normal temperature calibration sheet or the device to be tested. Through the synergistic effect of multiple modules, the problem of test errors caused by temperature fluctuation is effectively solved, and the precision and stability of radio frequency on-chip test are remarkably improved.

The invention relates to the technical field of bolt axial force measurement, and discloses a bolt pre-tightening force calculation system, method and device, computer equipment and a medium. An electromagnetic ultrasonic transmitting and receiving device in the system is used for transmitting a radio frequency pulse signal for an electromagnetic ultrasonic transducer; the electromagnetic ultrasonic transducer is used for receiving the radio-frequency pulse signal transmitted by the electromagnetic ultrasonic transceiver and acting the radio-frequency pulse signal on the tested bolt, so that ultrasonic waves are generated by excitation inside the tested bolt; the controller is used for obtaining ultrasonic wave corresponding sound time based on the ultrasonic wave and the synchronous extrusion wavelet transform algorithm and calculating the pretightening force of the measured bolt based on the corresponding sound time, accurate calculation of the pretightening force of the bolt is achieved, the method can be directly used for pretightening force calculation of bolts with poor surface quality and high temperature, and the method has high interference resistance to noise and is suitable for popularization and application. The problem that accurate measurement of the bolt pre-tightening force cannot be achieved when accurate ultrasonic sound of bolt ultrasonic waves cannot be obtained is solved.

A method of double-contrast magnetic resonance fingerprinting including: optimizing, using Cramér-Rao lower bound (CRLB) via a computer system, radiofrequency (RF) pulse parameters in an MRF sequence; loading, via the computer system, the RF pulse parameters optimized into an MRI scanner; and capturing raw k-space data by selecting different signal contrast modules for dual-contrast encoding at varying repetition times (TR); reconstructing, via the computer system, at least one image including a plurality of pixels; defining, via the computer system, a dynamic range and step size for tissue parameters; and creating, via the computer system, a dictionary based on Bloch equations, the dynamic range, and the step size; and comparing, via the computer system, signal evolution for each of the plurality of pixels in the at least one image to the dictionary to determine quantitative parameters for each of the plurality of pixels, and generating a quantitative parameter map.

The invention provides a wind power tower drum defect detection surface wave sensor and a detection method thereof. The sensor comprises a shell, a magnetic attraction part and a transmitting and receiving integrated signal part. The magnetic attraction component adopts a U-shaped structure and is formed by connecting two ends of a strip-shaped magnet with a magnetizer respectively; and the receiving and transmitting integrated signal component is positioned at the opening end of the U-shaped structure of the magnetic component. The sensor is adsorbed on the surface of the outer wall of a tower drum, meanwhile, a near surface layer of the outer wall of the tower drum presents a strong bias magnetic field, radio frequency pulse current is introduced into a transmitting and receiving integrated signal component, a high-frequency dynamic magnetic field is induced on the near surface, surface waves in any direction are excited and received under the action of the two fields, and echo signals of the surface waves are analyzed. And judging whether the outer wall of the tower drum has defects. The sensor disclosed by the invention is small in size and capable of meeting mobile scanning, the propagation distance of the excited surface wave is long, the recognition precision is high, the working difficulty of tower drum defect detection is reduced, circumferential and axial defect detection is realized, and the detection efficiency is improved.

The invention discloses a high-spatial-resolution distributed optical fiber sound wave sensing system based on FPGA real-time demodulation. The system comprises a narrow linewidth laser source module, a first coupler, a high-bandwidth sweep frequency signal modulation module, a circulator, a coherent receiving and photoelectric conversion module and an FPGA integrated module. A laser source emitted by the narrow linewidth laser source module is divided into about 10% of reference light and about 90% of detection light through the first coupler. The FPGA integrated module is connected with the high-bandwidth sweep frequency signal modulation module, and transmits a sweep frequency radio frequency pulse signal and a frequency shift radio frequency pulse signal to the high-bandwidth sweep frequency signal modulation module; the high-bandwidth sweep frequency signal modulation module is connected with the sensing optical fiber through the circulator so as to output sweep frequency optical pulses; the sensing optical fiber is connected with the coherent receiving and photoelectric conversion module through the circulator to transmit Rayleigh backscattered light; the coherent receiving and photoelectric conversion module is connected with the FPGA integrated module, and the FPGA integrated module carries out signal processing to obtain vibration information on the optical fiber.

The invention discloses a radio frequency and pulse radio frequency switchable power amplification circuit which comprises a crystal oscillator circuit, a radio frequency signal amplification circuit, a radio frequency and pulse radio frequency switching control circuit, an E-type control signal amplification circuit, two parallel AB-type power amplification circuits and a power synthesis and filter circuit. A radio frequency signal is generated by the crystal oscillator, and a pulse radio frequency signal or a radio frequency signal is output by adjusting the frequency and the duty ratio of the pulse control signal. Subsequently, the signals are amplified by the E-type power amplification circuit and are divided into a group of AB-type power amplification circuit control signals with equal amplitude and 180-degree phase difference by the transmission line transformer. The AB type power amplification circuit is formed by connecting two paths in parallel, each path is composed of four sets of AB type push-pull output modules, and each set is composed of two radio frequency MOSFETs to form AB type push-pull output. And finally, the power synthesis magnetic device performs power synthesis and filtering output. According to the high-power radio-frequency power supply, rapid switching between a high-power power supply radio-frequency mode and a pulse radio-frequency mode is realized, stable output under different output modes is ensured, and the applicability of the high-power radio-frequency power supply under complex conditions is improved.

The invention discloses a magnetron sputtering coating method with uniform coating and high target material utilization rate, and belongs to the technical field of film preparation, and the method realizes high-precision coating through whole-process collaborative optimization of pretreatment, sputtering, deposition and post-treatment. The substrate is cleaned in cooperation with radio-frequency pulse focusing bombardment; an electromagnetic coil group containing a temperature compensation coil is used for target sputtering, a magnetic field is dynamically adjusted in combination with laser profile sensing and a PID self-adaptive algorithm, and a direct current pulse-radio frequency composite power supply is matched to solve the target problem; in the deposition stage, a quartz crystal instrument is used for closed-loop film thickness control, metal film pulse gas supply and compound film reaction gas phase adjustment; gradient temperature rise is carried out according to data of an X-ray stress meter in post-treatment, and argon is used for dynamic protection and impurity prevention. According to the magnetron sputtering coating method with uniform coating and high target material utilization rate, the uniformity of coating and the target material utilization rate are improved, and the technological adaptability and stability of coating are improved.

The invention relates to the technical field of nuclear magnetic resonance, and discloses a frequency spectrum measurement method, device and equipment in nuclear magnetic resonance and a storage medium, a target sample is arranged in a uniform magnetic field, the target direction of the target sample is consistent with the uniform magnetic field, and the target sample is provided with a gradient coil; the method comprises the following steps: applying a linear gradient magnetic field in a target direction of a target sample; determining a uniform area of the radio frequency coil according to the bandwidth of the radio frequency pulse signal; during the period of receiving the nuclear magnetic resonance echo signal, the magnetic field size of the linear gradient magnetic field is adjusted under the condition of the target turning angle until the region of the nuclear magnetic resonance echo signal is constrained in the uniform region of the radio frequency coil, and a target linear gradient magnetic field is obtained; obtaining a target nuclear magnetic resonance echo signal according to the target linear gradient magnetic field; and performing inversion on the target nuclear magnetic resonance echo signal to obtain a T1-T2 spectrum. The problem of T1 end trailing caused by traditional T1-T2 measurement is solved, and the measurement precision is greatly improved.

The present disclosure provides systems and methods for removing electromagnetic interference from low-field magnetic resonance images. In one aspect, a method can include projecting a low-field strength magnetic field toward an object of interest located within a field of view and transmitting a radio frequency pulse sequence to a radio frequency coil assembly configured to selectively excite magnetization in the object of interest within the field of view. The method can further include receiving an output signal from the radio frequency coil assembly during a signal acquisition period and receiving a sample signal from the radio frequency coil assembly during an interference period. The method can further include comparing the output signal and the sample signal to identify an interference component and adjusting the output signal based on the interference component.

The invention belongs to the field of particle accelerator microwaves, and particularly relates to a C-band compact spherical microwave pulse compression device which comprises a shell, a dual-polarization mode coupler and a circular waveguide, a spherical energy storage cavity is formed in the shell, and the circular waveguide and the spherical energy storage cavity are communicated through a coupling hole; the dual-polarization mode coupler comprises a rectangular waveguide, a butterfly-shaped matching section and a cylindrical matching section. According to the klystron radio frequency pulse compression circuit, the radio frequency pulse with the pulse width of 2.5 microseconds of the klystron can be compressed to 300ns, the average power gain in a single pulse is more than 4 times, the peak power gain is 6.3 times, and the compression efficiency is about 54%. According to the dual-polarization mode coupler, the functions of power distribution, mode conversion and polarization mode generation are synchronously realized, a TE10 mode in a rectangular waveguide is converted into two polarization TE11 modes which are equal in amplitude and orthogonal in phase, and then the two orthogonal TE114 modes are excited in a spherical energy storage cavity.

A magnetic resonance imaging (MRI) apparatus that includes a multi-resonance transmit / receive (T / R) switch, one switch design having a top side and a bottom side of a microstripline based hybrid coupler, a first pin diode, a second pin diode, four vertical transmission lines and six horizontal transmission lines arranged in a bended manner on the microstripline. The top side is associated with a first port and a second port, and electrically connected to the first pin diode and the second pin diode. The bottom side is associated with a third port and a fourth port, and electrically connected with the first pin diode and the second pin diode. The switch receives radio frequency (RF) pulses of different frequencies transmitted to and received from an MRI RF coil where the different frequencies are received concurrently and without tuning by the multi-resonance T / R switch from the MRI RF coil.

The present disclosure relates to a target volume tracking method and a computer device. The method includes: determining an isocenter location corresponding to the target volume in a scout image of an object, and obtaining the spatial position of the treatment head in the radiotherapy device, and then determining the at least one slice on the scout image based on the isocenter location and the spatial position, so as to control the magnetic resonance scanner to radiate a RF pulse which excites the at least one slice to obtain a tracking image of the object; the tracking image includes the target volume.

The invention relates to a computer-implemented method for operating a magnetic resonance device (20) during a recording process according to a recording protocol, which comprises a plurality of sequence sections (1) of a magnetic resonance sequence in at least one repetition, wherein each sequence section (1) comprises a preparation module (8) and a readout module (10), and each readout module (10) comprises a plurality of readout submodules (2), in each of which radio-frequency pulses (12, 13) precede readout periods (6) for recording magnetic resonance data, wherein - in each readout module (10) at least one navigator submodule (11) is used to record navigator data of the sequence section (1), - for each sequence section (1), correlation information is determined by comparing the navigator data record of the sequence section (1) with at least one navigator data record of a further sequence section (1), and - the correlation information is evaluated to select sequence sections (1) whose magnetic resonance data are discarded and / or to assign a weighting to the magnetic resonance data of at least some of the sequence sections (1) before reconstructing a magnetic resonance image.

In a general aspect, a radar method includes transmitting an outgoing series of RF pulses toward a target region. The radar method also includes receiving an incoming series of RF pulses that is based on the outgoing series of RF pulses after passing through the target region. The radar method additionally includes producing, by operation of a vapor cell system, output signals that are based on incoming series of RF pulses and the laser signals interacting with a vapor of the vapor cell system. The radar method also includes operations of a signal processing system, such as generating response data, determining a Doppler shift, and determining a velocity of an object in the target region. The response data includes transient response data that represents transient responses of a vapor in the vapor cell system to respective phase changes in the incoming series of RF pulses.

The invention relates to the technical field of auxiliary medical treatment, and discloses a cold spraying control method of a radio frequency treatment system and the radio frequency treatment system. The method comprises the following steps: determining a first temperature change rate and a second temperature change rate of skin tissue in a current treatment area; wherein the first temperature change rate represents the temperature response of the skin tissue of the current treatment area to the refrigeration pulse, and the second temperature change rate represents the temperature response of the skin tissue of the current treatment area to the radio frequency pulse; and according to the first temperature change rate and the second temperature change rate, the single-time cold spraying duration of the current refrigeration pulse is determined. According to different responses of the skin tissue to temperature changes, the cold spraying duration is dynamically adjusted, it can be ensured that the temperature of the skin tissue is always kept within a safe and effective range, and it is ensured that the skin tissue in the current treatment area is prevented from being damaged while effective radio frequency treatment is conducted on the skin tissue.

The present disclosure describes a device, system, and methods for low-field magnetic resonance (MR) imaging. For example, a method for low-field MR imaging can include projecting a primary static magnetic field in a field of view, projecting a secondary static magnetic field to pre-polarize a first fluid moving toward the field of view, and acquiring a first image of the first fluid in the field of view based on a first RF pulse sequence. The method can further include projecting a tertiary static magnetic field to pre-polarize a second fluid moving toward the field of view and acquiring a second image of the second fluid in the field of view based on a second RF pulse sequence. The first image can be subtracted from the second image to generate a flow image of an object of interest positioned in the field of view.

The present disclosure provides an example method for using an MRI system electrically coupled to a computing device. The method includes generating, via the MRI system, an echo-shifted echo-planar imaging with blip up / down acquisition (“esEPI-BUDA”) pulse sequence including a first radiofrequency (“RF”) pulse and a second RF pulse, the first RF pulse followed by a first echo-train that is interleaved with the first and the second RF pulses, and the second RF pulse followed by a second echo-train such that the first and the second echo-trains have opposite phase-encoding blip gradient polarities to traverse echo planar imaging (“EPI”) k-space in a reversed order. In response to the pulse sequence being generated, the MRI system acquires two k-space datasets within a single shot and corrects image distortion, via the MRI system, based on the two acquired k-space datasets.

The invention relates to the technical field of radio frequency starting of medical cyclotrons, in particular to a radio frequency starting method and system of a medical cyclotron, and the method comprises the steps: carrying out the frequency sweeping when a radio frequency pulse in the medical cyclotron is started, and converting a radio frequency signal which is continuously adjusted in the frequency sweeping process into a radio frequency digital signal; analyzing noise characteristics formed after the radio frequency digital signals are converted into the radio frequency digital signals, and filtering noise interference in the radio frequency digital signals; the method specifically comprises the steps of calculating noise intensity at a current moment; acquiring a frequency sweeping rate sequence; calculating the Kalman gain at the current moment; filtering the radio frequency digital signal at the current moment by adopting a Kalman filtering method; and controlling the starting frequency of a radio frequency circuit in the medical cyclotron according to the filtered radio frequency digital signal at the current moment. According to the invention, the frequency sweeping operation is more accurate when the radio frequency of the medical cyclotron is started, and the tuning effect of the medical cyclotron is improved.

A time-efficient diffusion magnetic resonance imaging systems and methods are provided that can produce multiple diffusion-weighted images with different b-values in one repetition time, and / or multiple diffusion-weighted images with different diffusion times in one repetition time, both by utilizing a train of stimulated echoes. Each stimulated echo in the train of stimulated echoes is generated by a re-excitation radio-frequency (RE) pulse with a variable flip angle, following an initial 90° excitation RE pulse and a subsequent 90° restoration RE pulse.

The invention relates to NFC device detection. A device operating in a card emulation mode detects a first near field communication burst emitted by an external device. The first near field communication burst includes a first pulse of duration Tw. The device operating in card analog mode transmits a radio frequency pulse in response to an external device as a result of detecting a first pulse of a first near field communication burst. The duration of the radio frequency pulse is less than or equal to the duration Tw and is transmitted within a period of time less than or equal to 10 [mu] s from the leading edge of the first pulse of the first near field communication burst.

A method for optimization of an RF pulse for exciting spins in a slab in a magnetic resonance examination is provided. The RF pulse is to be played out with a coil having a plurality of independent parallel transmit elements. The method includes receiving complex B1+ field sensitivity maps for the plurality of parallel transmit elements and dividing the slab into at least two sub-slabs. For each sub-slab, B1+ shimming is performed to optimize the RF shim settings for the plurality of parallel transmit elements. The optimized RF shim settings are combined for each sub-slab to create a multiband RF pulse that simultaneously excites the spins in the complete slab.

The invention discloses a preparation method of a low-temperature plasma plating and permeating modified layer on the surface of a metal mold. The preparation method comprises the following steps: S1, precise pretreatment of a base body: sequentially carrying out mechanical grinding and polishing and ultrasonic cleaning on the base body, and then drying and putting the base body in a vacuum chamber; s2, plasma activation: after vacuumizing, introducing mixed gas of argon and hydrogen, generating glow discharge under the action of a pulse power supply, and performing sputtering activation on the surface of the substrate; s3, gradient transition layer plasma deposition is conducted, specifically, a pulse direct-current plasma source is adopted, a Ti target and a Cr target serve as sputtering sources, and a transition layer with components changing in a gradient mode is prepared; s4, plating and permeating a multi-element synergistic functional layer: preparing the functional layer by adopting a radio frequency-pulse direct-current composite plasma source, namely a Ti target, a Cr target, a Si-Al alloy target and a rare earth element target through synergistic sputtering; and S5, post-treatment optimization: performing vacuum cooling to room temperature after low-temperature annealing treatment to obtain a final modified layer. The permeation modified layer prepared by the method has high binding force, high hardness, high wear resistance and salt spray corrosion resistance.

The utility model discloses a radio frequency device for regulating and controlling skin temperature, which comprises a radio frequency signal generator for transmitting a radio frequency pulse signal and a pulse excitation signal for regulating and controlling the skin temperature; the electrode is used for receiving the radio-frequency pulse signal and generating a radio-frequency heat effect into the skin; the temperature sensor is arranged on the electrode or near the electrode and is used for detecting real-time temperature data of the skin in real time; the controller is used for controlling the radio frequency signal generator to output the pulse excitation signal for exciting the skin to reach the target temperature through one or more times based on the difference value between the temperature data and the target temperature; at least one of duty ratio, voltage and power of the pulse excitation signal is different from that of the radio frequency pulse signal, and the pulse width of the pulse excitation signal is smaller than that of the radio frequency pulse signal. When the real-time temperature data of the skin is abnormal in temperature rise, the skin is stimulated by one or more pulse excitation signals, so that the problem of abnormal temperature rise of the skin is effectively solved.

Method for magnetic resonance imaging, MRI, comprising obtaining an image acquisition sequence comprising RF pulses and magnetic field gradients configured to encode spatial information in a part of an object; obtaining an acoustic noise cancelling signal corresponding to the obtained image acquisition sequence at a first position; generating the image acquisition sequence; wherein the magnetic fields gradients are generated by gradient coils configured for three orthogonal directions respectively; and converting, by an acoustic transducer, simultaneously with the image acquisition sequence, the predetermined noise cancelling signal to an acoustic noise cancelling signal at the first position. The noise cancelling signal is obtained based on an acoustic transfer function and the magnetic field gradients of the image acquisition sequence, wherein the acoustic transfer function is obtained by training a neural network on a plurality of generic image acquisition sequences followed by transfer learning with calibration image acquisition sequences obtained during a calibration state before the generating of the image acquisition sequence.

The invention relates to a longitudinal relaxation time calculation method, nuclear magnetic resonance imaging equipment and a storage medium, and the method comprises the steps: executing a pulse sequence, and collecting a first multi-echo signal; the pulse sequence comprises a radio frequency pulse and a readout gradient, and the radio frequency pulse comprises a first excitation pulse and a plurality of second excitation pulses in a repetition time of the pulse sequence; the first multi-echo signal is a multi-echo signal acquired after executing a second excitation pulse; performing image reconstruction on the first multi-echo signal to obtain a multi-echo image; calculating target signal intensity according to a signal attenuation function and the information of the multi-echo image; and calculating the longitudinal relaxation time according to the target signal intensities of the plurality of repetition times. According to the invention, after a small number of first excitation pulses are applied, accurate longitudinal relaxation time distribution is obtained, and the problem of low calculation efficiency in the prior art is solved.

The present invention relates to the field of auxiliary medical technology, and discloses a cold spray control method for a radio frequency treatment system and a radio frequency treatment system. The method comprises: determining a first temperature change rate and a second temperature change rate of the skin tissue in the current treatment area; wherein the first temperature change rate characterizes the temperature response of the skin tissue in the current treatment area to the cooling pulse, and the second temperature change rate characterizes the temperature response of the skin tissue in the current treatment area to the radio frequency pulse; and determining the duration of a single cold spray of the current cooling pulse based on the first temperature change rate and the second temperature change rate. The present invention dynamically adjusts the cold spray duration based on the different responses of the skin tissue to temperature changes, thereby ensuring that the temperature of the skin tissue is always maintained within a safe and effective range, ensuring that while the skin tissue is effectively treated with radio frequency, damage to the skin tissue in the current treatment area is avoided.

The embodiment of the invention provides a magnetic resonance imaging method and system. The method may include acquiring magnetic resonance imaging data of a target object. Magnetic resonance imaging data may be acquired by applying a magnetic resonance imaging pulse sequence to a target object. The magnetic resonance imaging pulse sequence may include a single radio frequency pulse for exciting a first substance in a target object and suppressing a second substance in the target object. The method may further include reconstructing a magnetic resonance image of the target object based on the magnetic resonance imaging data.

A disclosed etching method includes (a) preparing a substrate on a substrate support in a chamber. The substrate includes a multilayer film including a plurality of first films and a plurality of second films that are alternately stacked with the plurality of first films, and a mask disposed on the multilayer film. The etching method further includes (b) etching one or more first films among the plurality of first films. The etching method further includes (c) etching one or more second films among the plurality of second films. In each of the (b) and (c), a pulse of a source radio frequency power for plasma generation and a pulse of an electric bias for ion attraction are intermittently or periodically supplied.

The invention relates to a preparation method of a high-hardness ultra-smooth TiN coating, which comprises the following steps: putting a workpiece into a vacuum chamber, vacuumizing the vacuum chamber, and then introducing Ar to carry out ion cleaning on the surface of the workpiece; sequentially depositing a Cr layer and a Ti layer on the surface of the workpiece by adopting a radio frequency sputtering technology; a TiN layer is prepared on the surface of a workpiece by adopting a pure ion plating technology, when pure ion plating is carried out, mixed gas of Ar and N is introduced into a vacuum chamber, auxiliary ionization is carried out on the mixed gas in the vacuum chamber, negative bias voltage is applied to the workpiece, the ionization rate of a Ti target is improved by adopting a radio-frequency pulse power supply, and an ion beam is filtered by using a bent pipe magnetic filter. According to the TiN coating prepared through the method, the hardness can be stably higher than 3000 HV, the binding force on a high-speed steel base material is larger than 50 N, and the binding force with the base material is remarkably improved; the N content in the prepared TiN coating is larger than 45%, the ionization degree is very high, compactness is good, and the surface roughness Ra is smaller than 10 nm.

A computer-implemented method for operating a magnetic resonance device during the acquisition of magnetic resonance data from an examination region of an examination object may use a magnetic resonance sequence. The MR sequence may include a saturation section in which, by means of a saturation radiofrequency pulse which is generated when a saturation gradient pulse is applied, a saturation with respect to a spin species that is to be imaged is performed in at least one first saturation region. The saturation radiofrequency pulse may be designed as a multiband pulse by means of which, in addition, in at least one second saturation region, the magnetization with respect to a second spin species that is not to be captured is saturated.