14 results about "Free induction decay" patented technology

The application relates to the technical field of magnetometers, and discloses a magnetic force sensor system based on free induction decay and a use method thereof.The sensor system comprises a laser generator, an atomic gas chamber, a strong magnetic field generator, a polarizer, an analyzer, and a first light detector, and a light splitting device is arranged between the laser generator and the atomic gas chamber, which can split the laser emitted by the laser generator into a first part of laser and a second part of laser, and make the first part of laser enter the atomic gas chamber and make the second part of laser enter a second light detector.Once the frequency of the laser generated by the laser generator changes, the proportion of the first part of laser and the second part of laser will change, and a feedback adjustment module feeds back and adjusts the laser generator according to the detection result of the second light detector, so that the laser emitted by the laser generator is the laser with a preset frequency, thereby realizing rapid and high-precision adjustment of the laser emitted by the laser generator, and further improving the detection precision of the whole magnetic force sensor system.

The invention relates to a computer-implemented method for acquiring magnetic resonance data with a magnetic resonance device (18), wherein a magnetic resonance sequence is used in which, during an equilibrium state in a sequence segment maintained by regular excitation modules (9, 9a - 9e) with at least one excitation pulse, both a first readout time window (11, 11a - 11e) immediately following an excitation module (9, 9a - 9e) for measuring magnetic resonance data of a free induction decay and second readout time windows (12, 12a - 12e), which are spaced at least the first readout duration of the first readout time window (11, 11a - 11e) from a last excitation module (9, 9a - 9e), which acts as a refocusing module for the penultimate excitation module (9, 9a - 9e), are used for measuring magnetic resonance data of a spin echo. become,wherein, between at least one pair consisting of a starting excitation module (9c) and a final excitation module (9d) that follow one another, a fat saturation module (15) with at least one high-frequency fat saturation pulse (16) is output in the magnetic resonance sequence during a preparation period (14).

A method for relaxation time determination includes delivering a series of radio frequency (RF) pulses in a sequence to a specimen having a magnetic resonance spin system. The pulses are separated by equal time intervals and the sequence has a duration comparable or greater than a spin-lattice relaxation time for the spin system. The method includes receiving a response after each RF pulse in the series. The response includes a free induction decay and spin echoes. The method includes generating a series of single point imaging (SPI) images from each response. Each SPI image of the series corresponds to an RF pulse in the series. The method includes converting SPI images to a spin-spin relaxation map and a spin-lattice relaxation map.

Computer-implemented method for recording MR data, including: executing a MR sequence having a sequence segment maintained in a steady state by regular excitation modules, each excitation module including an excitation pulse; for each excitation module, providing: a first read-out time window for measuring MR data of a free induction decay; and a second read-out time window, occurring after a last excitation module by at least a duration of the first read-out time window, the last excitation module acting as a refocusing module for the penultimate excitation module, wherein both read-out time windows follow an excitation module and are used to measure MR data of a spin echo; and outputting, in a preparation period between a pair of excitation modules comprising a beginning excitation module and a concluding excitation module that follow one another in the MR sequence, a fat saturation module including a RF fat saturation pulse.

Systems and techniques are provided for determining a time zero echo of a nuclear magnetic resonance (NMR) sequence. An example method includes obtaining, via an NMR tool in a borehole, echo waveforms associated with refocusing pulses and a free induction decay (FID) waveform associated with an excitation pulse; determining echo values based on the echo waveforms and an apparent time-zero echo value based on the FID waveform, the apparent time-zero echo value representing a time zero echo; applying a correction factor to the apparent time-zero echo value to yield a corrected time zero echo value; and determining a spectrum associated with a sample based on an inversion performed on the corrected time zero echo values and the set of echo values before or after a conversion of the corrected time zero echo value and the set of echo values to porosity units, the conversion of the corrected time zero echo value and the set of echo values being based on one or more conversion factors.

The invention discloses a conductive medium detection method and device, the method is suitable for a transient magnetic field exciter, and the method comprises the steps: responding to a detection demand of a detected area, and applying a background field to an atomic gas chamber along a first direction parallel to a magnetic field coil; starting the first detection light and controlling the first detection light to pass through the atomic gas chamber along a second direction; synchronously starting the pump light and the magnetic field coil according to a preset detection frequency, controlling the pump light to penetrate through the magnetic field coil to enter the atomic gas chamber, and controlling the magnetic field coil to send a pulsed magnetic field to the detected area; and synchronously closing the pump light and the magnetic field coil in a preset time window to obtain second detection light generated after the first detection light passes through the atomic gas chamber, so as to obtain free induction attenuation signals of atoms in the atomic gas chamber and a detection result of a transient eddy current magnetic field, and determining a detection result of the conducting medium in the detected area according to the detection result. And the detection precision and the response rate are improved.

The purpose of the present invention is to provide a biological component adsorption material that has high adsorption performance with respect to biological components, particularly with respect to cytokines, independently from the content and / or chemical structure of a ligand. The present invention provides a biological component adsorption material comprising water-insoluble material which comprises a base material that includes a scaffold polymer, a linker that is bound to the base material, and ligand that is bound to the linker, wherein the water-insoluble material exhibits a T2 relaxation time of retrained amorphous component of 0.0210-0.0270 ms, as seen in free induction decay (FID) observed with 1H-pulse NMR using a solid echo method.

The application provides a denoising method for magnetic resonance spectrum based on a transformer, and relates to the technical field of signal processing and artificial intelligence, which comprises the following steps: obtaining a free induction decay signal (FID) containing noise and a corresponding label signal, and constructing a training data set; converting the FID into a frequency domain signal through fast Fourier transform and performing amplitude normalization; projecting the real part and the imaginary part of the frequency domain signal into a high-dimensional feature space respectively; and feeding the two channels into a multi-layer transformer encoder based on a multi-head self-attention mechanism respectively to capture long sequence global correlation. The encoding output is separated and decoded to recover the real part and the imaginary part respectively, and the recovered complex frequency domain signal is obtained by combination. During the training process, a complex mean square error is used as a loss function, and a dynamic learning rate scheduling and an early stopping mechanism are combined to improve the convergence stability and the model training efficiency.

To provide a deterioration sign diagnosis method and a deterioration sign diagnosis system of a resin material capable of easily diagnosing a sign of deterioration of the resin material.SOLUTION: The resin material deterioration sign diagnosis method according to the embodiment includes measuring a resin material by a nuclear magnetic resonance apparatus capable of non-destructive observation, acquiring free induction decay curve data, obtaining a spin-spin relaxation time, evaluating a change in molecular mobility of the resin material based on the spin-spin relaxation time, and diagnosing a deterioration sign of the resin material.SELECTED DRAWING: Figure 5

The present invention provides a film having a low coefficient of linear expansion. A film according to the present invention contains an organopolysiloxane, and the signal intensity of the free induction decay associated with spin-spin relaxation of all protons at room temperature was measured for the film using the CPMG technique for solid state NMR, a fitting process according to formula (I) was performed using the signal intensity, and among three components A, B, and C, in order of shortest relaxation time, the relaxation time T2c of the component C was 2.0 milliseconds or less.

This invention relates to a method for measuring the wax content of crude oil using nuclear magnetic resonance (NMR), comprising: heating the crude oil sample to be tested to a homogeneous fluid state and then injecting it into a sample tube; cooling the sample tube in a low-temperature environment to allow complete precipitation of paraffin wax in the crude oil; placing the cooled sample tube in an NMR instrument and acquiring NMR signals using a free induction decay sequence; performing a two-component fitting on the acquired NMR signals to obtain the initial signal amplitudes A1 and A2 of the solid and liquid phases, and calculating the ratio x between the initial signal amplitudes of the solid and liquid phases based on A1 and A2; calculating the mass ratio y between the solid and liquid phases using a pre-established calibration model y=k·x; and calculating the wax content c of the crude oil sample to be tested based on the solid-liquid mass ratio y. This invention also relates to a corresponding system. The method and system for measuring the wax content of crude oil using NMR of this invention effectively solve the problems of long testing time and environmental unfriendliness associated with the national standard method.

The invention discloses a seasonal river water environment quality evaluation method based on chemical research service data, and the method comprises the following steps: 1, deploying a low-field nuclear magnetic resonance online detection device on each sampling section, applying a radio frequency excitation pulse to a water sample entering a detection cavity, and collecting a free induction attenuation signal; collecting the one-dimensional nuclear magnetic resonance spectrum vectors of the sampling sections according to seasonal division to form a nuclear magnetic resonance spectrum data set; 2, constructing a one-dimensional convolutional neural network model, and forming a pollutant feature matrix corresponding to each sampling section in each season; and step 3, establishing classic domain matter elements and joint domain matter elements corresponding to each water quality grade according to a water environment quality standard, and summarizing water environment quality evaluation grades of each sampling section in each season to form a seasonal river water environment quality comprehensive evaluation result. According to the invention, on-site rapid detection and automatic spectrogram analysis of organic pollutants are realized, and the problem of poor timeliness of traditional off-line detection is overcome.

The invention discloses a rubidium atom magnetometer based on free induction attenuation and a magnetic field measurement method. The magnetometer physical probe comprises a VCSEL laser, an optical shaping unit composed of a convex lens, a polaroid and a 1 / 4 wave plate, a rubidium atom gas chamber, a radio frequency coil assembly and a photoelectric detector. The circuit part comprises a signal conditioning circuit and an oscillation feedback circuit. The method comprises the following steps: working in a periodic pulse mode, firstly starting a laser and radio frequency coil in a period, and performing optical pumping and polarization on rubidium atoms by using left-hand circularly polarized light and a polarized magnetic field along an optical axis; then, the polarized magnetic field is rapidly closed within microsecond magnitude time, so that the atoms spin and freely precession in the external magnetic field to be measured, and an FID signal is generated; after being detected by the photoelectric detector, the signals are fed back to the radio frequency coil through amplification and phase locking processing, and self-oscillation with the frequency locked at the atomic Larmor precession frequency is formed; and measuring the oscillation frequency and calculating the external magnetic field intensity according to the gyromagnetic ratio. The invention has the advantages of high sensitivity, large bandwidth, fast response and small volume.

The application discloses a kind of atomic magnetometer vector magnetic field measurement method and measuring device, it is related to quantum precision measurement technical field.The method includes: alkali metal atom in atomic gas chamber is optically pumped to establish spin alignment state;Pulse radio frequency magnetic field is applied to induce atom to generate free induction decay signal;Based on the reference free induction decay signal collected when not applying additional bias magnetic field, the environmental background magnetic field modulus is determined;Known intensity additional bias magnetic field is sequentially applied in three orthogonal axes, and based on the additional free induction decay signal under corresponding state, the total magnetic field modulus corresponding to each orthogonal axis is determined;Combining geometric relationship demodulation obtains the vector component of environmental magnetic field on each orthogonal axis.The present application does not need complex optical modulation equipment, while maintaining single-beam compact configuration, high-precision three-dimensional vector magnetic field measurement is realized, and system power consumption and hardware complexity are significantly reduced.