The aluminum shielded room has been an important part of ultra-low-field magnetic resonance imaging(ULF MRI)based on the superconducting quantum interference device(SQUID). The shielded room is effective to attenuate ...The aluminum shielded room has been an important part of ultra-low-field magnetic resonance imaging(ULF MRI)based on the superconducting quantum interference device(SQUID). The shielded room is effective to attenuate the external radio-frequency field and keep the extremely sensitive detector, SQUID, working properly. A high-performance shielded room can increase the signal-to-noise ratio(SNR) and improve image quality. In this study, a circular coil with a diameter of 50 cm and a square coil with a side length of 2.0 m was used to simulate the magnetic fields from the nearby electric apparatuses and the distant environmental noise sources. The shielding effectivenesses(SE) of the shielded room with different thicknesses of aluminum sheets were calculated and simulated. A room using 6-mm-thick aluminum plates with a dimension of 1.5 m×1.5 m×2.0 m was then constructed. The SE was experimentally measured by using three-axis SQUID magnetometers, with tranisent magnetic field induced in the aluminum plates by the strong pre-polarization pulses. The results of the measured SE agreed with that from the simulation. In addition, the introduction of a 0.5-mm gap caused the obvious reduction of SE indicating the importance of door design. The nuclear magnetic resonance(NMR) signals of water at 5.9 kHz were measured in free space and in a shielded room, and the SNR was improved from 3 to 15. The simulation and experimental results will help us design an aluminum shielded room which satisfies the requirements for future ULF human brain imaging. Finally, the cancellation technique of the transient eddy current was tried, the simulation of the cancellation technique will lead us to finding an appropriate way to suppress the eddy current fields.展开更多
Carbon capture,utilization and storage (CCUS) is considered as a very important technology for mitigating global climate change.Carbon dioxide (CO2) injected into an underground reservoir will induce changes in its ph...Carbon capture,utilization and storage (CCUS) is considered as a very important technology for mitigating global climate change.Carbon dioxide (CO2) injected into an underground reservoir will induce changes in its physical properties and the migration of CO2 will be affected by many factors.Accurately understanding these changes and migration characteristics of CO2 is crucial for selecting a CCUS project site,estimating storage capacity and ensuring storage security.In this paper,the basic principles of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) technologies are briefly introduced in the context of laboratory experiments related to CCUS.The types of NMR apparatus,experimental samples and testing approaches applied worldwide are discussed and analyzed.Then two typical NMR core analysis systems used in CCUS field and a self-developed high-pressure,low-field NMR rock core flooding experimental system are compared.Finally,a summary of the current deficiencies related to NMR applied to CCUS field is given and future research plans are proposed.展开更多
3.0T magnetic resonance spectroscopic imaging is a commonly used method in the research of brain function in Alzheimer's disease.However,the role of 7.0T high-field magnetic resonance spectroscopic imaging in brai...3.0T magnetic resonance spectroscopic imaging is a commonly used method in the research of brain function in Alzheimer's disease.However,the role of 7.0T high-field magnetic resonance spectroscopic imaging in brain function of Alzheimer's disease remains unclear.In this study,7.0T magnetic resonance spectroscopy showed that in the hippocampus of Alzheimer's disease rats,the N-acetylaspartate wave crest was reduced,and the creatine and choline wave crest was elevated.This finding was further supported by hematoxylin-eosin staining,which showed a loss of hippocampal neurons and more glial cells.Moreover,electron microscopy showed neuronal shrinkage and mitochondrial rupture,and scanning electron microscopy revealed small size hippocampal synaptic vesicles,incomplete synaptic structure,and reduced number.Overall,the results revealed that 7.0T high-field nuclear magnetic resonance spectroscopy detected the lesions and functional changes in hippocampal neurons of Alzheimer's disease rats in vivo,allowing the possibility for assessing the success rate and grading of the amyloid beta(1–40) animal model of Alzheimer's disease.展开更多
Nuclear magnetic resonance(NMR) is one of the most powerful tools to explore new quantum states of condensed matter induced by high magnetic fields at a microscopic level. High magnetic field enhances the intensity of...Nuclear magnetic resonance(NMR) is one of the most powerful tools to explore new quantum states of condensed matter induced by high magnetic fields at a microscopic level. High magnetic field enhances the intensity of the NMR signal, and more importantly, can induce novel phenomena. In this article, examples are given on the field-induced charge density wave(CDW) in high-Tc superconductors and on the studies of quantum spin liquids. We provide a brief introduction to the high magnetic field NMR platform, the station 4 of the Synergetic Extreme Condition User Facility(SECUF), being built at Huairou, Beijing.展开更多
This paper analyses the heteronuclear Cosy Revamped by Asymmetric Z-gradient Echo Detection pulse sequence.General theoretical expressions of the pulse sequence with arbitrary flip angles were derived by using dipolar...This paper analyses the heteronuclear Cosy Revamped by Asymmetric Z-gradient Echo Detection pulse sequence.General theoretical expressions of the pulse sequence with arbitrary flip angles were derived by using dipolar field treatment and signals originating from heteronuclear intermolecular single-quantum coherences (iSQCs) in highly-polarized two spin-1/2 systems were mainly discussed in order to find the optimal flip angles.The results show that signals from heteronuclear iSQCs decay slower than those from intermolecular double-quantum coherences or intermolecular zero-quantum coherences.Magical angle experiments validate that the signals are from heteronuclear iSQCs and insensitive to the imperfection of radio-frequency flip angles.All experimental observations are in excellent agreement with theoretical predictions.The quantum-mechanical treatment leads to similar predictions to the dipolar field treatment.展开更多
The correlated spectroscopy revamped by asymmetric Z-gradient echo detection (CRAZED) sequence is modified to investigate intermolecular double-quantum coherence nuclear magnetic resonance signal dips in highly polari...The correlated spectroscopy revamped by asymmetric Z-gradient echo detection (CRAZED) sequence is modified to investigate intermolecular double-quantum coherence nuclear magnetic resonance signal dips in highly polarized spin systems. It is found that the occurrence of intermolecular double-quantum coherence signal dips is related to sample geometry, field inhomogeneity and dipolar correlation distance. If the field inhomogeneity is refocused, the signal dip occurs at a fixed position whenever the dipolar correlation distance approaches the sample dimension. However, the position is shifted when the field inhomogeneity exists. Experiments and simulations are performed to validate our theoretic analysis. These signal features may offer a unique way to investigate porous structures and may find applications in biomedicine and material science.展开更多
Strong and extremely homogeneous static magnetic field is usually required for high-resolution nu-clear magnetic resonance (NMR). However, in the cases of in vivo and so on, the magnetic field inho-mogeneity owing to ...Strong and extremely homogeneous static magnetic field is usually required for high-resolution nu-clear magnetic resonance (NMR). However, in the cases of in vivo and so on, the magnetic field inho-mogeneity owing to magnetic susceptibility variation in samples is unavoidable and hard to eliminate by conventional methods such as shimming. Recently, intermolecular multiple quantum coherences (iMQCs) have been employed to eliminate inhomogeneous broadening and obtain high-resolution NMR spectra, especially for in vivo samples. Compared to other high-resolution NMR methods, iMQC method exhibits its unique feature and advantage. It simultaneously holds information of chemical shifts, multiplet structures, coupling constants, and relative peak areas. All the information is often used to analyze and characterize molecular structures in conventional one-dimensional NMR spec-troscopy. In this work, recent technical developments including our results in this field are summarized; the high-resolution mechanism is analyzed and comparison with other methods based on interactions between spins is made; comments on the current situation and outlook on the research directions are also made.展开更多
For generating a uniform and steady magnetic field, Helmholtz coil is extensively used in nuclear magnetic resonance gyro(NMRG). Unfortunately, the volume of Helmholtz coil makes it inconvenient to miniaturize NMRG. T...For generating a uniform and steady magnetic field, Helmholtz coil is extensively used in nuclear magnetic resonance gyro(NMRG). Unfortunately, the volume of Helmholtz coil makes it inconvenient to miniaturize NMRG. This study introduces Braunbeck coil that can be used in magnetic field excitation system. Braunbeck coil can produce homogeneous magnetic field within a limit space, and occupy a small volume. In addition, this study presents mathematical expressions that can be used to calculate the area of uniform magnetic field. Experimental test verifies the effectiveness of the proposed design, and the results accord closely with the actual simulation.展开更多
The resistivity experimental measurements of core samples drilled from low permeability reservoirs of Ordos Basin,Northwest China,illustrate that the cementation factors are not agminate,but vary from 1.335 to 1.749.T...The resistivity experimental measurements of core samples drilled from low permeability reservoirs of Ordos Basin,Northwest China,illustrate that the cementation factors are not agminate,but vary from 1.335 to 1.749.This leads to a challenge for the estimation of water and hydrocarbon saturation.Based on the analysis of Purcell equation and assumption that rock resistivity is determined by the parallel connection of numerous capillary resistances,a theoretical expression of cementation factor in terms of porosity and permeability is established.Then,cementation factor can be calculated if the parameters of porosity and permeability are determined.In the field application,porosity can be easily obtained by conventional logs.However,it is a tough challenge to estimate permeability due to the strong heterogeneity of low permeability reservoirs.Thus,the Schlumberger Doll Research(SDR)model derived from NMR logs has been proposed to estimate permeability.Based on the analysis of the theoretical expressions of cementation factor and SDR model,a novel cementation factor prediction model,which is relevant to porosity and logarithmic mean of NMR T2spectrum(T2lm),is derived.The advantage of this model is that all the input information can be acquired from NMR logs accurately.In order to confirm the credibility of the novel model,the resistivity and corresponding laboratory NMR measurements of 27 core samples are conducted.The credibility of the model is confirmed by comparing the predicted cementation factors with the core analyzed results.The absolute errors for all core samples are lower than 0.071.Once this model is extended to field application,the accuracy of water and hydrocarbon saturation estimation will be significantly improved.展开更多
该文对不同发酵阶段的黄酒样品进行低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)检测,比较了陈酿时间、酒精度和品牌对黄酒低场核磁弛豫特性的影响,最后对9个品牌黄酒的LF-NMR弛豫信息进行了主成分分析。结果表明,发酵...该文对不同发酵阶段的黄酒样品进行低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)检测,比较了陈酿时间、酒精度和品牌对黄酒低场核磁弛豫特性的影响,最后对9个品牌黄酒的LF-NMR弛豫信息进行了主成分分析。结果表明,发酵后样品的单组分弛豫时间(T_(2W))显著缩短,而陈酿后黄酒的T_(2W)又相对延长。多组分弛豫图谱(T_(2))表明,对照组和浸米样品均只有1个峰。发酵后样品的T_(2)图谱均出现2个峰。从第一次发酵到煎酒期间,T_(21)和T_(22)不断缩短,而陈酿期间T_(21)和T_(22)相对延长。同一品牌及陈酿时间的黄酒,酒精度越大,体系的T_(2W),T_(21)和T_(22)越短;同一品牌及酒精度下,陈酿时间仅对T_(21)有一定影响。不同品牌黄酒因酿造工艺的区别而使弛豫分布有一定特点。主成分分析表明,不同酒精度、陈酿时间、品牌及种类的黄酒的弛豫特性的PCA分布及间距不同。说明应用LF-NMR技术可实现对不同工艺生产的黄酒的快速辨别。展开更多
大豆含油率的高低直接影响榨油与育种结果。为探究大豆含油率的最佳检测方法与构建含油率高低判别模型,该研究基于不同维度低场核磁共振(low field nuclear magnetic resonance,LF-NMR)技术,以国标法为对照,利用LF-NMR波谱和LF-NMR含油...大豆含油率的高低直接影响榨油与育种结果。为探究大豆含油率的最佳检测方法与构建含油率高低判别模型,该研究基于不同维度低场核磁共振(low field nuclear magnetic resonance,LF-NMR)技术,以国标法为对照,利用LF-NMR波谱和LF-NMR含油含水率软件检测大豆含油率;核磁共振成像(magnetic resonance imaging,MRI)结合深度学习,建立大豆含油率高低判别模型。引入低场二维核磁共振(low field two-dimensional nuclear magnetic resonance,LF-2D-NMR)技术,定性分析一维波谱中信号重叠无法区分组分的问题。试验结果表明,LF-NMR含油含水率软件能快速准确检测大豆含油率,T1-T2二维核磁图谱成功解决了自由水和油信号重叠问题。利用U-net++深度学习模型对MRI成像的矢状面、冠状面、横截面以及三面混合数据集进行训练,其中横截面评价指标与其他数据集相比更优,语义分割部分中平均交并比(mean intersection over union,mIoU)约0.9058,全局准确率0.9980,训练后的模型能够将MRI图像识别并分割,快速判别大豆含油率高低。试验证明,LF-NMR及MRI能够快速无损掌握大豆含油率信息,为大豆的高油育种提供了新思路和技术支持。展开更多
基金Project supported in part by the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB04020200)in part by the National Natural Science Foundation of China(Grant No.11204339)
文摘The aluminum shielded room has been an important part of ultra-low-field magnetic resonance imaging(ULF MRI)based on the superconducting quantum interference device(SQUID). The shielded room is effective to attenuate the external radio-frequency field and keep the extremely sensitive detector, SQUID, working properly. A high-performance shielded room can increase the signal-to-noise ratio(SNR) and improve image quality. In this study, a circular coil with a diameter of 50 cm and a square coil with a side length of 2.0 m was used to simulate the magnetic fields from the nearby electric apparatuses and the distant environmental noise sources. The shielding effectivenesses(SE) of the shielded room with different thicknesses of aluminum sheets were calculated and simulated. A room using 6-mm-thick aluminum plates with a dimension of 1.5 m×1.5 m×2.0 m was then constructed. The SE was experimentally measured by using three-axis SQUID magnetometers, with tranisent magnetic field induced in the aluminum plates by the strong pre-polarization pulses. The results of the measured SE agreed with that from the simulation. In addition, the introduction of a 0.5-mm gap caused the obvious reduction of SE indicating the importance of door design. The nuclear magnetic resonance(NMR) signals of water at 5.9 kHz were measured in free space and in a shielded room, and the SNR was improved from 3 to 15. The simulation and experimental results will help us design an aluminum shielded room which satisfies the requirements for future ULF human brain imaging. Finally, the cancellation technique of the transient eddy current was tried, the simulation of the cancellation technique will lead us to finding an appropriate way to suppress the eddy current fields.
基金supported by the Open Research Fund of State Key Laboratory of Geomechanics and GeotechnicalEngineering, IRSM, CAS (Grant No. Z017002)the National Natural Science Foundation of China (Grant Nos. 41872210 and 41274111)financial support from the China-Australia Geological Storage of CO_2 (CAGS) Project funded by the Australian Government under the auspices of the China-Australia Joint Coordination Group on Clean Coal Technology
文摘Carbon capture,utilization and storage (CCUS) is considered as a very important technology for mitigating global climate change.Carbon dioxide (CO2) injected into an underground reservoir will induce changes in its physical properties and the migration of CO2 will be affected by many factors.Accurately understanding these changes and migration characteristics of CO2 is crucial for selecting a CCUS project site,estimating storage capacity and ensuring storage security.In this paper,the basic principles of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) technologies are briefly introduced in the context of laboratory experiments related to CCUS.The types of NMR apparatus,experimental samples and testing approaches applied worldwide are discussed and analyzed.Then two typical NMR core analysis systems used in CCUS field and a self-developed high-pressure,low-field NMR rock core flooding experimental system are compared.Finally,a summary of the current deficiencies related to NMR applied to CCUS field is given and future research plans are proposed.
基金supported by the National Natural Science Foundation of China,No.81141013a grant for Talents in Beijing,No.2011D003034000019
文摘3.0T magnetic resonance spectroscopic imaging is a commonly used method in the research of brain function in Alzheimer's disease.However,the role of 7.0T high-field magnetic resonance spectroscopic imaging in brain function of Alzheimer's disease remains unclear.In this study,7.0T magnetic resonance spectroscopy showed that in the hippocampus of Alzheimer's disease rats,the N-acetylaspartate wave crest was reduced,and the creatine and choline wave crest was elevated.This finding was further supported by hematoxylin-eosin staining,which showed a loss of hippocampal neurons and more glial cells.Moreover,electron microscopy showed neuronal shrinkage and mitochondrial rupture,and scanning electron microscopy revealed small size hippocampal synaptic vesicles,incomplete synaptic structure,and reduced number.Overall,the results revealed that 7.0T high-field nuclear magnetic resonance spectroscopy detected the lesions and functional changes in hippocampal neurons of Alzheimer's disease rats in vivo,allowing the possibility for assessing the success rate and grading of the amyloid beta(1–40) animal model of Alzheimer's disease.
基金Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB07020200)the National Key Research and Development Program of China(Grant Nos.2016YFA0300502 and 2015CB921304)the National Natural Science Foundation of China(Grant No.11634015)
文摘Nuclear magnetic resonance(NMR) is one of the most powerful tools to explore new quantum states of condensed matter induced by high magnetic fields at a microscopic level. High magnetic field enhances the intensity of the NMR signal, and more importantly, can induce novel phenomena. In this article, examples are given on the field-induced charge density wave(CDW) in high-Tc superconductors and on the studies of quantum spin liquids. We provide a brief introduction to the high magnetic field NMR platform, the station 4 of the Synergetic Extreme Condition User Facility(SECUF), being built at Huairou, Beijing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos 20573084 and 10575085)the Nation Science Foundation of Fujian,China(Grant No A0610005)the Program for New Century Excellent Talents in University of Ministry of Education of China
文摘This paper analyses the heteronuclear Cosy Revamped by Asymmetric Z-gradient Echo Detection pulse sequence.General theoretical expressions of the pulse sequence with arbitrary flip angles were derived by using dipolar field treatment and signals originating from heteronuclear intermolecular single-quantum coherences (iSQCs) in highly-polarized two spin-1/2 systems were mainly discussed in order to find the optimal flip angles.The results show that signals from heteronuclear iSQCs decay slower than those from intermolecular double-quantum coherences or intermolecular zero-quantum coherences.Magical angle experiments validate that the signals are from heteronuclear iSQCs and insensitive to the imperfection of radio-frequency flip angles.All experimental observations are in excellent agreement with theoretical predictions.The quantum-mechanical treatment leads to similar predictions to the dipolar field treatment.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10875101 and 11074209)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090121110030)
文摘The correlated spectroscopy revamped by asymmetric Z-gradient echo detection (CRAZED) sequence is modified to investigate intermolecular double-quantum coherence nuclear magnetic resonance signal dips in highly polarized spin systems. It is found that the occurrence of intermolecular double-quantum coherence signal dips is related to sample geometry, field inhomogeneity and dipolar correlation distance. If the field inhomogeneity is refocused, the signal dip occurs at a fixed position whenever the dipolar correlation distance approaches the sample dimension. However, the position is shifted when the field inhomogeneity exists. Experiments and simulations are performed to validate our theoretic analysis. These signal features may offer a unique way to investigate porous structures and may find applications in biomedicine and material science.
基金Supported by the National Natural Science Foundation of China (Grant Nos.20573084,10575085 and 10774125)
文摘Strong and extremely homogeneous static magnetic field is usually required for high-resolution nu-clear magnetic resonance (NMR). However, in the cases of in vivo and so on, the magnetic field inho-mogeneity owing to magnetic susceptibility variation in samples is unavoidable and hard to eliminate by conventional methods such as shimming. Recently, intermolecular multiple quantum coherences (iMQCs) have been employed to eliminate inhomogeneous broadening and obtain high-resolution NMR spectra, especially for in vivo samples. Compared to other high-resolution NMR methods, iMQC method exhibits its unique feature and advantage. It simultaneously holds information of chemical shifts, multiplet structures, coupling constants, and relative peak areas. All the information is often used to analyze and characterize molecular structures in conventional one-dimensional NMR spec-troscopy. In this work, recent technical developments including our results in this field are summarized; the high-resolution mechanism is analyzed and comparison with other methods based on interactions between spins is made; comments on the current situation and outlook on the research directions are also made.
基金the National Natural Science Foundation of China(Nos.30800235 and 31271069)the Shanghai Aerospace Science and Technology Innovation Fund(No.SAST2016084)+1 种基金the Medical Engineering and Science Interdisciplinary Fund of Shanghai Jiao Tong University(No.YG2013MS24)the Shanghai Sailing Program(No.17YF1408200)
文摘For generating a uniform and steady magnetic field, Helmholtz coil is extensively used in nuclear magnetic resonance gyro(NMRG). Unfortunately, the volume of Helmholtz coil makes it inconvenient to miniaturize NMRG. This study introduces Braunbeck coil that can be used in magnetic field excitation system. Braunbeck coil can produce homogeneous magnetic field within a limit space, and occupy a small volume. In addition, this study presents mathematical expressions that can be used to calculate the area of uniform magnetic field. Experimental test verifies the effectiveness of the proposed design, and the results accord closely with the actual simulation.
基金supported by the Major National Oil&Gas Specific Project of China(No.2011ZX05044)
文摘The resistivity experimental measurements of core samples drilled from low permeability reservoirs of Ordos Basin,Northwest China,illustrate that the cementation factors are not agminate,but vary from 1.335 to 1.749.This leads to a challenge for the estimation of water and hydrocarbon saturation.Based on the analysis of Purcell equation and assumption that rock resistivity is determined by the parallel connection of numerous capillary resistances,a theoretical expression of cementation factor in terms of porosity and permeability is established.Then,cementation factor can be calculated if the parameters of porosity and permeability are determined.In the field application,porosity can be easily obtained by conventional logs.However,it is a tough challenge to estimate permeability due to the strong heterogeneity of low permeability reservoirs.Thus,the Schlumberger Doll Research(SDR)model derived from NMR logs has been proposed to estimate permeability.Based on the analysis of the theoretical expressions of cementation factor and SDR model,a novel cementation factor prediction model,which is relevant to porosity and logarithmic mean of NMR T2spectrum(T2lm),is derived.The advantage of this model is that all the input information can be acquired from NMR logs accurately.In order to confirm the credibility of the novel model,the resistivity and corresponding laboratory NMR measurements of 27 core samples are conducted.The credibility of the model is confirmed by comparing the predicted cementation factors with the core analyzed results.The absolute errors for all core samples are lower than 0.071.Once this model is extended to field application,the accuracy of water and hydrocarbon saturation estimation will be significantly improved.
文摘该文对不同发酵阶段的黄酒样品进行低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)检测,比较了陈酿时间、酒精度和品牌对黄酒低场核磁弛豫特性的影响,最后对9个品牌黄酒的LF-NMR弛豫信息进行了主成分分析。结果表明,发酵后样品的单组分弛豫时间(T_(2W))显著缩短,而陈酿后黄酒的T_(2W)又相对延长。多组分弛豫图谱(T_(2))表明,对照组和浸米样品均只有1个峰。发酵后样品的T_(2)图谱均出现2个峰。从第一次发酵到煎酒期间,T_(21)和T_(22)不断缩短,而陈酿期间T_(21)和T_(22)相对延长。同一品牌及陈酿时间的黄酒,酒精度越大,体系的T_(2W),T_(21)和T_(22)越短;同一品牌及酒精度下,陈酿时间仅对T_(21)有一定影响。不同品牌黄酒因酿造工艺的区别而使弛豫分布有一定特点。主成分分析表明,不同酒精度、陈酿时间、品牌及种类的黄酒的弛豫特性的PCA分布及间距不同。说明应用LF-NMR技术可实现对不同工艺生产的黄酒的快速辨别。
文摘大豆含油率的高低直接影响榨油与育种结果。为探究大豆含油率的最佳检测方法与构建含油率高低判别模型,该研究基于不同维度低场核磁共振(low field nuclear magnetic resonance,LF-NMR)技术,以国标法为对照,利用LF-NMR波谱和LF-NMR含油含水率软件检测大豆含油率;核磁共振成像(magnetic resonance imaging,MRI)结合深度学习,建立大豆含油率高低判别模型。引入低场二维核磁共振(low field two-dimensional nuclear magnetic resonance,LF-2D-NMR)技术,定性分析一维波谱中信号重叠无法区分组分的问题。试验结果表明,LF-NMR含油含水率软件能快速准确检测大豆含油率,T1-T2二维核磁图谱成功解决了自由水和油信号重叠问题。利用U-net++深度学习模型对MRI成像的矢状面、冠状面、横截面以及三面混合数据集进行训练,其中横截面评价指标与其他数据集相比更优,语义分割部分中平均交并比(mean intersection over union,mIoU)约0.9058,全局准确率0.9980,训练后的模型能够将MRI图像识别并分割,快速判别大豆含油率高低。试验证明,LF-NMR及MRI能够快速无损掌握大豆含油率信息,为大豆的高油育种提供了新思路和技术支持。
