86 results about "Transverse relaxation" patented technology

A method for determining properties of a mixture of fluids includes: (a) acquiring a plurality of nuclear magnetic resonance measurements from the mixture of fluids, each of the plurality of nuclear magnetic resonance measurements having a different value in an acquisition parameter for which at least one relaxation selected from the group consisting of longitudinal relaxation and transverse relaxation affects magnitudes of the nuclear magnetic resonance measurements; (b) generating a model of the mixture of fluids; (c) calculating a synthesized nuclear magnetic data set based on the model; (d) comparing the synthesized nuclear magnetic data set with the nuclear magnetic resonance measurements; and (e) adjusting the model and repeating (c) and (d), if difference between the synthesized nuclear magnetic data set and the nuclear magnetic measurements is greater than a minimum.

The invention discloses a method for measuring the oil content of drilling fluid through low-field NMR (Nuclear Magnetic Resonance), suitable for measuring the content of crude oil with different densities in the drilling fluid. The method comprises the step of measuring the oil content of the drilling fluid by using the transverse relaxation time of the crude oil and the drilling fluid and different diffusion coefficients as main identification criteria, using the signal strength of NMR of the crude oil and the drilling fluid as a main observation object and using the transverse relaxation analysis of the drilling fluid and the correlation analysis of the diffusion coefficients and transverse relaxation as main measures. The method of the invention has the advantages of high measuring result accuracy, good stability, short time consumption, and the like, is easy to realize the online measurement of the oil content of the drilling fluid and provides reliable storage information of an oil layer for logging operation.

The invention relates to the field of magnetic resonance imaging technique, in particular to a magnetic resonance fast spin echo (FSE) imaging method, comprising the steps as follows: 1. phase coding gradient amplitude is reset, pre-scanning is carried out by FSE pulse sequence, the amplitude value of each etch signal peak on the echo chain is recorded; 2. the phase and inclination angle of convergence pulse is adjusted so as to lead the amplitude of each echo signal peak on the echo chain to achieve the maximum value, when the amplitude value Am and phase angle Phim of each echo signal peak are recorded; 3. the phase coding gradient is recovered, the scanning is carried out by the FSE pulse sequence, thus gaining the K space data; 4. according to the amplitude Am and Fai<m> of each echo signal peak gained in step 2, the K space data is corrected; 5. image reconstruction is carried out by the corrected K space data thus gaining the magnetic resonance images, etc. The magnetic resonance fast spin echo (FSE) imaging method solves the problems of echo amplitude phase oscillation and image blurring due to transverse relaxation of the prior art.

The invention relates to a device and a method for detecting gas-liquid diffusion processes by using an MRI technique, and belongs to the technical field of chemical engineering and petroleum engineering. The device comprises a magnetic resonance imaging system and a dual chamber pressure attenuation system. The magnetic resonance imaging system is provided with a rock core clamper in a magnetic resonance imaging instrument which is electrically connected with a data acquisition and processing system. According to the device and the method for detecting gas-liquid diffusion processes by using the MRI technique, proton density images, longitudinal and transverse relaxation and diffusion tensor distribution images of fluids in porous media can be measured in real time, visually and with no damage through the MRI technique. Quantitative analysis can be performed on porous medium porosity, permeability, saturation level and the like; an improved dual chamber pressure attenuation method can reduce the leakage rate, and confirm the initial gas density conveniently and accurately; and a magnetic suspension balance can monitor gas density changes in real time, and accordingly, deficiencies of traditional dual chamber pressure attenuation methods are compensated.

The invention relates to a method for testing tobacco water content based on a time-domain nuclear magnetic resonance inversion peak area. The method is characterized in that a CPMG sequence is used on a time domain time-domain nuclear magnetic resonance, 4-6 of the tobacco standard samples with different qualities are measured, a transverse relaxation spectrum of the standard sample is obtained by SIRT inversion of an original data, a primary peak area of the transverse relaxation spectrum is recorded, the water content of the standard sample is measured by using a microwave drying method, a standard curve of the primary peak area data and the water content of the standard sample is established, the sample with water content to be measured is measured, the obtained primary peak value is substituted into the standard curve, the water content of the to-be-measured sample is obtained, and the water content of the to-be-measured sample is obtained. The interference of an oil signal in a tobacco sample can be eliminated, influence of oil fraction in the tobacco is not generated, detection speed is fast, and the result is accurate. The sample preparation and solvent consumption are not required, the defect that the oil and water signals in the tobacco cannot be distinguished when a nuclear magnetic signal method is used for measuring water content of the tobacco, and the accuracy for measuring the water content of the tobacco oil-water signal sample is increased.

A method is described for determination of the content of at least one component of a sample by means of a nuclear magnetic resonance pulse spectrometer, with the magnetization of the sample being influenced by a sequence of radio-frequency pulses such that the signal amplitudes to be observed can be determined. The magnetization of the sample is initially saturated, and the signal amplitudes which are determined at each time by the longitudinal and transverse relaxation times T1 and T2 and / or T2* and / or T1p, from which a value for the content of the at least one component is determined, are measured at the same time in a cohesive experimental procedure.

The invention belongs to the field of building materials, and particularly relates to a method for rapidly and continuously representing cement hydration degrees by means of a low-field nuclear magnetic resonance technology. The method comprises the following steps that 1, slurry is prepared, weighing is conducted, the water content m<0> and the cement content m<c> in the cement slurry are calculated, the slurry is rapidly put in a low-field nuclear magnetic resonance instrument, and test is conducted after system parameters and sampling interval time are set; 2, a CPMG impulse sequence is adopted to collect nuclear magnetic resonance transverse relaxation decay signals at t moments in different hydration time; 3, first echo peak amplitudes I(t) of a decay curve at the t moments in the different hydration time are automatically collected, and an amplitude I<0> of a first collection point is recorded; 4, physical combined water amounts m(t) at the hydration t moments are determined through the specific value of the I(t) to the I<0>, and hydration degrees alpha(t) at the hydration t moments are obtained according to the formula in the specification; 5, a relation curve of the alpha(t) and t is drawn, and the hydration degrees at any hydration t moment can be read. According to the method for rapidly and continuously representing the cement hydration degrees by means of the low-field nuclear magnetic resonance technology, drying or stopping of hydration to samples is not needed, and in-situ detection and continuous monitoring to the cement hydration degrees can be achieved.

The invention provides a method for nondestructive detection of water and fat contents of yellow croaker. The method comprises 1, yellow croaker sample detection: acquiring a transverse relaxation signal through a CPMG sequence so that a yellow croaker sample transverse relaxation spectrum is obtained, 2, determination of yellow croaker water and fat contents, 3, building of yellow croaker water and fat content prediction models: building prediction models through the T2 relaxation spectrum as an independent variable and water and fast contents as dependent variables, and 4, signal data analysis and processing. The method researches correlation of the spectrum and ingredients, utilizes yellow croaker low field nuclear magnetic resonance relaxation data as a research object and yellow croaker water and fast contents as indexes to build the yellow croaker water and fat content PCR and PLSR prediction models and realizes fast detection of water and fat contents of the yellow croaker.

A nuclear magnetic resonance transverse relaxation measurement method without J-coupling-effect interference is suitable for a routine liquid magnetic resonance spectrometer. The nuclear magnetic resonance transverse relaxation measurement method without J-coupling-effect interference can eliminate the J-coupling-effect interference. The method comprises the steps of (1), measuring a pi / 2 nonselective RF pulse width required for exciting a sample; (2), introducing a nuclear magnetic resonance pulse sequence into the magnetic resonance spectrometer; (3), starting a transverse relaxation evolution module and a pure chemical shift decoupling module based on a perfect echo for the nuclear magnetic resonance pulse sequence, and setting experiment parameters of the transverse relaxation evolution module and the pure chemical shift decoupling module; (4), performing three-dimensional data sampling; and (5), after data sampling, performing related data after-processing operation, and obtaining a two-dimensional spectrum of which the direct dimension is the pure chemical shift information and the indirect dimension is the transverse relaxation time and error, namely a pure chemical shift-transverse relaxation time two-dimensional correlation spectrum.

The invention discloses an NMR relaxation semaphore calibrating device and method for an aquo-complex sediment by combining an X-CT technology. The device comprises a reaction kettle, an NMR testing system, an X-CT scanning system, an aquo-complex synthesizing system, a temperature pressure control system and a vacuumizing saturated system. The vacuumizing saturated system is connected to the reaction kettle for vaccumizing saturated treatment of the sediment in the reaction kettle. The NMR testing system and the X-CT scanning system are used for scanning and testing microporous structures ofthe aquo-complex sediment and analyzing the behavior characteristics of the aquo-complex sediment in pore scale in the forming and decomposing processes. By means of the device, calibration of nuclearmagnetism transverse relaxation semaphore and the behavior measurement and analysis in the pore scale can be integrated, thereby laying a technical foundation for discussing a micromechanism of basicphysical parameter change of the aquo-complex sediment.

A single-scan synchronous magnetic resonance diffusion and T2 imaging method based on overlapping echoes, relates to magnetic resonance imaging. Four echoes are produced by using a small angle excitation pulse and two echo chain samplings with two identical deflection angles, and each echo chain collects two echo signals. There is an evolution time and a pair of diffusion gradients after the firstexcitation pulse, due to which the transverse relaxation times and diffusion weights of the two echo signals in the first sampling are different. A shifting gradient of frequency dimension and phasedimension is added after each excitation pulse so that the signals generated by the different excitation pulses are different in position in the k-space. Two echo signals are re-converged with one refocusing pulse after finishing the first sampling, and then the second sampling is performed, in which two echo signals with the same transverse relaxation time and different diffusion weights can be obtained. The sampled signal is reconstructed using deep learning to obtain quantitative T2 and ADC images, and T2 and ADC images can be obtained in a single-scan.

An embodiment in accordance with the present invention provides a new acquisition scheme for T2-weighted BOLD fMRI. It employs a T2 preparation module to induce the BOLD contrast, followed by a single-shot 3D fast gradient echo (GRE) readout with short echo time (TE<2 ms). The separation of BOLD contrast generation from the readout substantially reduces the “dead time” due to long TE required in spin echo (SE) BOLD sequences. This approach termed “3D T2prep-GRE,” can be implemented with any magnetic resonance imaging machine, known to or conceivable by one of skill in the art. This approach is expected to be useful for ultra-high field fMRI studies that require whole brain coverage, or focus on regions near air cavities. The concept of using T2 preparation to generate BOLD contrast can be combined with many other fast imaging sequences at any field strength.

The invention discloses a quantitative evaluation method for the generating efficiency of natural gas hydrate in rocks on the basis of low field nuclear magnetic resonance. According to the method, the advantage that the low field nuclear magnetic resonance is sensitive to a hydrogenous fluid and insensitive to a hydrogenous solid in the rocks is fully used, transverse relaxation signals of complete water-bearing rocks and natural gas hydrate contained rocks are measured, and transverse relaxation signals are converted to be T2 spectrums by adopting a regularized inversion algorithm, the areasof the T2 spectrums are respectively calculated, and the generating efficiency of natural gas hydrate in rocks can be determined according to changes of the areas of the T2 spectrums. The quantitative evaluation method provided by the invention can effectively overcome the defect, in the prior art, of low accuracy caused by that the saturability of the natural gas hydrate is formerly used for evaluating natural gas hydrate in seabed rocks, effectively improves the natural gas hydrate detection efficiency, and has an important significance on quantitative evaluation and prediction of natural gas hydrate quantity.

The invention discloses a detection method of change rule of plastisol moulding degree of nitro-cotton (NC) in a high-solid-content propellant. The method includes the steps of: a) firstly aging the propellant at a certain temperature for different times t to obtain a series of samples, and processing the samples into blocks being not more than 15*10*10 (mm*mm*mm) in size, and placing the sample blocks in special test tubes and performing low field nuclear magnetic detection to obtain transverse relaxation times T2 of the samples; and b) with the T2 as y-coordinate and t as x-coordinate, drawing a T2-t curve, which can reflect the change rule of the plastisol moulding degree of the NC in the samples with the t. The method, during detection, is free of change on spatial status of the NC and can actually show the plastisol moulding degree of the NC. The change rule of the plastisol moulding degree of the NC in the propellant with the t can serve as a basis of determining security service life of the propellant. The method also is a researching mean, wherein formula of the propellant can be regulated or manufacturing process can be improved by comparing the plastisol moulding degree of the NC in the propellants having similar formulas or being prepared through different technologies.

The invention discloses a method for characterizing porous structure of cement-hardened paste by utilizing low-field nuclear magnetic resonance cryoporometry technology. The method comprises the following steps: a) preparing a test sample as required; b) putting the test sample into a low-field nuclear magnetic resonance instrument sample room with temperature changing function, and acquiring the nuclear magnetic resonance transverse relaxation attenuation semaphore I (T) of the test sample in different temperature range (-30DEG C to 1DEG C) by adopting CPMG pulse sequence according to certain temperature intervals; c) performing bracketing to the completely tested test sample, gradually drying and testing the linear relationship of nuclear magnetic resonance transverse relaxation attenuation semaphore and the quality of the test sample, to obtain a slope k; d) calculating the pore volume of the test sample in unit mass through a formula; and e) obtaining the differential pore size distribution curve and logarithmic differentiation pore size distribution curve of the test sample respectively through the formula. By adopting the method, the pore size distribution situation of cement-hardened paste of 1nm to 1000nm can be accurately measured.

The present invention is a non-destructive testing method for peanut varieties based on nuclear magnetic resonance technology. The specific steps are as follows: select a number of peanut samples, respectively perform nuclear magnetic resonance transverse relaxation scanning on the peanut samples through a CPMG sequence, and process them with a one-dimensional inverse Laplacian algorithm. Obtain the signal quantity of the sample unit mass; use the principal component analysis method to process the peak point data of the CPMG sequence of each peanut sample, and obtain the principal component scatter diagram of each peanut sample; take the unknown variety peanut and use the same CPMG sequence to analyze the unknown variety peanut The sample is scanned by nuclear magnetic resonance transverse relaxation, and the measured CPMG sequence peak point data is obtained for principal component analysis, and the variety of the unknown peanut sample is determined by comparing the principal component scatter diagram of each peanut sample obtained in step S2. The method of the invention has outstanding advantages such as fast analysis speed, high analysis efficiency, no pollution to the environment, no impact on the health of experiment operators, etc., and can provide reliable basis for analyzing and identifying peanut varieties.

The invention relates to a core oil / water calibration method based on a nuclear magnetic resonance transverse relaxation spectrum line (see Fig. 1 for the block diagram of the operation procedure). According to the method, in the process of saturating a core with oil / water before a core flooding experiment, the corresponding relationship between the oil / water mass or volume in the core and the peak area of a nuclear magnetic resonance T2 relaxation signal is tested, that is, a more accurate calibration result of the oil / water mass or volume and the signal amplitude is obtained without affecting the experimental operation procedure, so that the calibration is achieved. By using the calibration result, the change of the oil / water mass or volume in the core can be directly obtained by testingthe T2 relaxation spectrum line in the core flooding process, and the mass / volume and the recovery ratio of the produced oil / water can be further determined. According to the scheme of the invention,the key information of a nuclear magnetic resonance core flooding experiment is calibrated in real time based on the nuclear magnetic resonance T2 relaxation spectrum and the actual core flooding experiment, so that the accuracy and reliability of the experimental data can be improved, and the interference to the subsequent core flooding experiment cannot occur.

The invention discloses a brand-new nuclear magnetic resonance echo mechanism based magnetic resonance imaging method. The method includes: turning dispersion-phase spins to a longitudinal plane, andsubstituting transverse relaxation with longitudinal relaxation to reduce signal relaxation attenuation; combining with a brand-new echo generating mechanism to obtain completely gathered echo on a transverse plane to keep signals as far as possible, so that a signal-to-noise ratio of an imaging sequence is substantially increased. The method has advantages that the defect of respective signal loss of traditional echo sequences (spin echoes and stimulated echoes) is overcome, optimal echo signals are formed, sequence schemes comprehensively superior to the spin echoes and the stimulated echoesare provided for echo sequence applying diffusion imaging and flow imaging, the signal-to-noise ratio of images is increased to obtain high-quality images, and accordingly an accurate and reliable quantitative measurement method is provided for magnetic resonance in bulk diffusion and flow imaging, and a promising application prospect in biological medical research and clinical diagnosis is achieved.

The invention provides a method for nondestructively testing trepang autolysis on basis of a nuclear magnetic resonance technique. The method comprises the following steps: carrying out nuclear magnetic resonance signal collection on the trepang under the same parameters by adopting a magnetic resonance imaging analyzer and utilizing a CMPG sequence, thereby acquiring a transverse relaxation spectrum; and then judging the change of the content of free water in the trepang according to the degree of left shifting of T2 relaxation peak. According to the method for analyzing the water content change in the trepang autolysis process through low-field nuclear magnetic resonance provided by the invention, the transverse relaxation time spectrum T2 and the magnetic resonance imaging of the fresh bowel-cut trepang are taken as main analyzing basis, so as to quickly judge the water content change in the trepang autolysis process. The method provided by the invention has the advantages that the accuracy of the measuring result is high, the consumed time is short, the sample is free from being damaged, the inner visible information of the sample can be supplied, and the like. The reliable information is supplied to the detection for the autolysis process of the bowel-cut trepang and the change in the quality during the autolysis process of the bowel-cut trepang.

The invention relates to a texture quality non-destructive testing method in a sea cucumber heating process. The texture quality non-destructive testing method includes the steps: A) establishing a low field nuclear magnetic resonance transverse relaxation spectrum information database in the sea cucumber heating process; B) establishing a texture information database in the sea cucumber heating process; C) analyzing correlation information between the low field nuclear magnetic resonance transverse relaxation spectrum information obtained in the step A) and the texture information obtained in the step B); D) carrying out low field nuclear magnetic resonance testing on to-be-detected sea cucumber, to obtain transverse relaxation spectrum information; and E) comparing the transverse relaxation spectrum information obtained in the step D) with the low field nuclear magnetic resonance relaxation spectrum database information in the sea cucumber heating process established in the step A), selecting similar low field nuclear magnetic resonance relaxation spectrum database information as a reference value, according to the correlation information, which is obtained in the step C), between the low field nuclear magnetic resonance transverse relaxation spectrum information and the texture information, referring to the information of the texture information database established in the step B), and speculating to obtain a texture characteristic speculation value of the sample sea cucumber.

The invention discloses a bone mineral density detection equipment and detection method based on a magnetic resonance T2 relaxation time spectrum. A bone mineral density is detected based on the magnetic resonance T2 relaxation time spectrum. The detection equipment comprises a computer control terminal, a one-board magnetic resonance controller unit, a signal amplification and switch control unit and a magnet unit. According to the bone mineral density detection equipment and detection method, water molecule magnetic resonance transverse relaxation deamplification is measured firstly, the corresponding T2 relaxation time spectrum is obtained through a mathematical inversion method, structural characteristics of pores among bone trabeculae are determined by analyzing all peak values on the T2 relaxation time spectrum, and biological bone mineral density data is obtained through a regression analysis data processing method finally. The bone mineral density detection equipment and detection method can be applied to identification of osteoporosis, the functions of rapidly and nondestructively analyzing and measuring the bone mineral density, evaluating the bone quality and the like are achieved, and the bone mineral density detection equipment and detection method have the advantages of being safe and harmless to organisms, simple in equipment structure, small in size, light in weight, high in measurement precision, easy and convenient to operate, high in repeatability of measurement method and the like.

A method for quantifying bitumen and / or water in a sample comprising bitumen, water and solids using a time-domain nuclear magnetic resonance pulse spectrometer is provided comprising the steps of: initially saturating the magnetization of the sample so that essentially no magnetization remains in the +Z axis; subjecting the sample to a sequence of radio-frequency pulses optimized for the measurement of bitumen and water in the sample; allowing the recording of the transverse relaxation (T2) echo trains after incremental longitudinal relaxation to produce a raw TD-NMR data set for the sample; and determining the amount of bitumen and water by means of a partial least squares optimization based chemometric model relating TD-NMR data sets obtained from a training set of samples comprising bitumen, water and solids to the training samples' corresponding reference values obtained from a standard analysis method for determining bitumen and water.

The invention provides a quick caviar quality detection method based on the low-field nuclear magnetic resonance technology. The quick caviar quality detection method comprises the following steps that spawns of sturgeon are collected, pickled and poured into cans, and caviar is obtained and stored at minus 4 DEG C for 11 months; the spawns and stored caviar samples are subjected to low-field nuclear magnetic resonance analysis in all the stages, and a low-field nuclear magnetic resonance transverse relaxation spectrum information database is established; the actual fat content, the actual moisture content and the actual color difference value of all the samples are measured, and an information database for the moisture content, the fat content and the color difference value in the pickling and storage processes of caviar is established; a detection model is established, correlation analysis is carried out, and the quality of a spawn or caviar sample to be detected is judged. The method is short in consumed time, high in accuracy and good in repeatability, an organic reagent is not needed, the samples do not need to be pretreated, visualized information of the internal structure of food can be obtained, and meanwhile the speculation values of the physical and chemical indexes in the caviar storage process can be speculated.

The invention discloses a novel D-T2 pulse applying method based on a pulse gradient magnetic field. Even magnetic field design is adopted in a main instrument magnetic field, the pulse gradient magnetic field is applied to a tested region through a gradient coil, and the pulse gradient and lasting time can be adjusted; a data acquisition pulse time sequence is divided into two windows on a time axis, the lasting time of the first window is fixed to be t0, and the shortest instrument echo interval is used for acquiring a CPMG pulse time sequence of the second window; spectrum unfolding is conducted on echo signals acquired in the two windows through an inversion algorithm so that a D-T2 two-dimensional distribution map of reservoir stratum pore fluid can be acquired. The method has the two unique advantages that firstly, a diffusion coefficient measurement range is large; secondly, the transverse relaxation resolution ratio is high, D-T2 two-dimensional nuclear magnetic resonance acquisition parameters are set more flexibly through unique double-variant design, and the method can well suitable for the changes of the nuclear magnetic resonance property of the reservoir stratum pore fluid.

The invention relates to a method for testing the rosin content of pine sawn timber based on time domain nuclear magnetic resonance. The method is characterized by comprising the steps that a CPMG sequence is used on a time domain nuclear magnetic resonance spectrometer, different-quality standard samples of the vacuum-dried pine sawn timber of a certain tree species are measured, original nuclearmagnetic resonance relaxation attenuation curves of obtained test samples are subjected to inversion calculation to obtain transverse relaxation distribution spectrums of the standard samples, the total area of the transverse relaxation distribution spectral peak of each standard sample is recorded, then the rosin content in the standard samples is determined through a Soxhlet extraction method,a standard curve of the total area of the transverse relaxation distribution spectral peak and the rosin content of the standard samples is established, then the sample with the rosin content to be detected is measured, the obtained total area of the relaxation distribution spectral peak is substituted into the standard curve, the rosin content of the to-be-detected sample is obtained, and then the proportion of the rosin content of the to-be-detected sample can be solved. According to the method, the detecting speed is high, the result is accurate, and a complex chemical solvent extraction experiment is not needed.

A magnetic resonance imaging (MRI) method for imaging components with short transverse relaxation times (T2) is provided, in which a human or an animal heart is subjected to a segmented spoiled gradient echo (SPGR) sequence. Each segment of this SPGR sequence comprises a plurality of basic sequence elements in each of which a radiofrequency (RF) pulse and a frequency encoding gradient moment kx are applied, in order to generate an MRI signal at an echo time TE1. The RF pulses and the frequency encoding gradient moments kx are applied such, that in different basic sequence elements the MRI signal is generated at varying echo times TE1, in order to reduce the effective echo time in the center of k-space. The segments of the SPGR sequence are synchronized with at least one measured cycle indicator reflecting the timing of the cardiac cycles. The MRI signals generated by the SPGR sequence are used for reconstructing at least one first cardiac image.