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1.
在简易磁屏蔽室中,用单通道的高温超导 rf SQUID梯度计构成心磁图(MCG)测量系统,依照MCG测定部位的约定,测得数例成人胸前多点MCG.不计心动周期随时间的变化,用数据分析软件对这些MCG数据进行分析处理, 得到包括了空间信息、可直观展示心脏电磁活动的二维心磁图谱(例如等磁图、时序等磁图、电流箭头图和时序电流箭头图等).  相似文献   

2.
本文研究了一种自建的低成本简易磁屏蔽室及其操控条件,提出了能被高温超导rf SQUID仪器所接受的简易磁屏蔽室,并且运用由该磁屏蔽室和rf SQUID梯度计所构成的组合系统测量了微弱的生物磁信号.研究结果表明,该磁屏蔽室能够有效降低电磁干扰,确保SQUID长时稳定工作,基于该磁屏蔽室的复合MCG测量系统具备捕捉微弱生物磁信号的能力,且所得信号具有可接受的信噪比.这将使得开发一种低造价的实用高温超导MCG测量系统成为现实.  相似文献   

3.
在简易磁屏蔽室中,用单通道的高温超导rf SQUID梯度计构成心磁图(MCG)测量系统,依照MCG测定部位的约定,测得数例成人胸前多点MCG.不计心动周期随时问的变化,用数据分析软件对这些MCG数据进行分析处理,得到包括了空间信息、可直观展示心脏电磁活动的二维心磁图谱(例如等磁图、时序等磁图、电流箭头图和时序电流箭头图等)  相似文献   

4.
本文研究了一种自建的低成本简易磁屏蔽室及其操控条件,提出了能被高温超导rf SQUID仪器所接受的简易磁屏蔽室,并且运用由该磁屏蔽室和rf SQUID梯度计所构成的组合系统测量了微弱的生物磁信号.研究结果表明,该磁屏蔽室能够有效降低电磁干扰,确保SQUID长时稳定工作,基于该磁屏蔽室的复合MCG测量系统具备捕捉微弱生物磁信号的能力,且所得信号具有可接受的信噪比.这将使得开发一种低造价的实用高温超导MCG测量系统成为现实.  相似文献   

5.
四面体磁梯度张量系统的载体磁干扰补偿方法   总被引:2,自引:0,他引:2       下载免费PDF全文
于振涛  吕俊伟  毕波  周静 《物理学报》2014,(11):139-144
针对搭载于水下无人航行器(UUV)的四面体磁梯度张量系统易受载体磁场干扰的问题,提出了一种载体磁干扰补偿方法.该方法在载体磁干扰产生机理的基础上,利用磁梯度张量差分测量算法融合四面体磁梯度张量系统中四个矢量磁力仪的载体磁干扰,建立了磁梯度张量系统载体磁干扰数学模型;然后在此数学模型的基础上提出了磁干扰补偿方法,并根据磁梯度张量9分量的数学关系提出了补偿参数辨识方法;最后通过仿真实验对方法进行了验证,结果表明该补偿方法可以有效补偿磁梯度张量系统95.9%的载体磁干扰.该方法利用补偿参数对磁梯度张量系统的输出值直接进行磁干扰补偿,从理论上解决了磁梯度张量系统中各个矢量磁力仪载体磁干扰的统一补偿问题.  相似文献   

6.
中国科学院上海微系统与信息技术研究所自主研制了9通道心磁图仪,可在闹市区的简易磁屏蔽环境中稳定工作.本系统包含9个信号通道和3个参考通道,通过采集人体的36点心磁信号,可提供等磁图、伪电流密度图等一系列磁成像,供医生解读.本文主要基于该系统进行了完整的性能测试与评估,测得该系统多周期时域噪声水平优于4pT,系统带宽为DC-40Hz,9个信号通道的磁场-电压转换系数约为2500pT/V、系统摆率达0.3×106Φ0/s.目前,该系统已经成功采集接近50余例志愿者的心磁数据,为临床研究提供了极具价值的医学信息.  相似文献   

7.
中国科学院上海微系统与信息技术研究所自主研制了9通道心磁图仪,可在闹市区的简易磁屏蔽环境中稳定工作.本系统包含9个信号通道和3个参考通道,通过采集人体的36点心磁信号,可提供等磁图、伪电流密度图等一系列磁成像,供医生解读.本文主要基于该系统进行了完整的性能测试与评估,测得该系统多周期时域噪声水平优于4pT,系统带宽为DC-40Hz,9个信号通道的磁场-电压转换系数约为2500pT/V、系统摆率达0.3×106Φ0/s.目前,该系统已经成功采集接近50余例志愿者的心磁数据,为临床研究提供了极具价值的医学信息.  相似文献   

8.
心磁图(Magnetocardiography)是一种无创性记录和分析心脏电磁场的方法.由于心磁场强度极其弱小,必须使用超导量子干涉仪(SQUID)才能检测,其中心磁信号消噪处理十分重要.本文对心磁测量中的消噪进行了研究,在小波分析的基础上,提出使用小波包分析方法消噪,通过实验发现小波包分析消噪能获得很好的效果.  相似文献   

9.
静止无功发生器(Static Var Generator, SVG)具有提高系统功率因数、动态改善电能质量、稳定电网以及节能降耗、降低运行成本等优点.针对其优点,作为水冷磁体电源的使用需求,考虑将高压链式SVG技术作为磁体电源无功补偿的方案,以实现无功动态补偿.本文主要介绍了链式串联SVG的工作原理,对其参数进行设计并利用PSCAD进行仿真实验,实验验证了方案的可行性,为强光磁关键技术预研项目14 MW水冷磁体电源无功补偿装置提供了理论支持.  相似文献   

10.
静止无功发生器(Static Var Generator, SVG) 具有提高系统功率因数、 动态改善电能质量、 稳定电网以及节能降耗、 降低运行成本等优点. 针对其优点, 作为水冷磁体电源的使用需求, 考虑将高压链式 SVG 技术作为磁体电源无功补偿的方案, 以实现无功动态补偿. 本文主要介绍了链式串联 SVG 的工作原理, 对其参数进行设计并利用 PSCAD 进行仿真实验, 实验验证了方案的可行性, 为强光磁关键技术预研项目14 MW 水冷磁体电源无功补偿装置提供了理论支持  相似文献   

11.
SQUID gradiometer techniques are widely used in noise cancellation for biomagnetic measurements.An appropriate gradiometer baseline is very important for the biomagnetic detection with high performance.By placing several magnetometers at different heights along the vertical direction,we could simultaneously obtain the synthetic gradiometers with different baselines.By using the traditional signal-to-noise ratio(SNR) as a performance index,we successfully obtain an optimal baseline for the magnetocardiography(MCG) measurement in a magnetically shielded room(MSR).Finally,we obtain an optimal baseline of 7 cm and use it for the practical MCG measurement in our MSR.The SNR about 38 dB is obtained in the recorded MCG signal.  相似文献   

12.
Kang Yang 《中国物理 B》2022,31(7):70701-070701
For a magnetocardiography (MCG) system inside a magnetically shielded room (MSR), the residual field should be further suppressed to obtain high-quality MCG signals. In this paper, a compensation system has been developed based on the bi-planar coil and the proportional-integral-derivative (PID) controller. The bi-planar coil, derived from the target-field theory and the Tikhonov regularization method, is utilized to generate magnetic field with high uniformity in the pre-defined target region. And the PID controller is introduced to provide dynamic compensation current for the coil, according to the residual field change monitored by a reference SQUID magnetometer. The measurement results show that the noise suppression ratio (NSR) can reach above 20 dB in the low-frequency range from 0.1 Hz to 50 Hz. The DC component and the fluctuation of the residual field in time-domain can be respectively suppressed to 0 pT and 4 pT, indicating that this proposed compensation method is useful for the MCG measurement.  相似文献   

13.
Magnetocardiography(MCG)measurement is important for investigating the cardiac biological activities.Traditionally,the extremely weak MCG signal was detected by using superconducting quantum interference devices(SQUIDs).As a room-temperature magnetic-field sensor,optically pumped magnetometer(OPM)has shown to have comparable sensitivity to that of SQUIDs,which is very suitable for biomagnetic measurements.In this paper,a synthetic gradiometer was constructed by using two OPMs under spin-exchange relaxation-free(SERF)conditions within a moderate magnetically shielded room(MSR).The magnetic noise of the OPM was measured to less than 70 fT/Hz1/2.Under a baseline of 100 mm,noise cancellation of about 30 dB was achieved.MCG was successfully measured with a signal to noise ratio(SNR)of about 37 dB.The synthetic gradiometer technique was very effective to suppress the residual environmental fields,demonstrating the OPM gradiometer technique for highly cost-effective biomagnetic measurements.  相似文献   

14.
We present a new filter scheme for magnetocardiogram (MCG) signal processing based on the quasi-periodic characteristic of the signals. The key points of this scheme are to determine the exact numbers of data points in each cardiac cycle by using electrocardiogram (ECG) data acquired simultaneously with the MCG signal and to normalize the MCG data sequence in each cycle into an identical length. Compared with conventional filters, the scheme has the advantage of more powerful noise suppression with less signal distortion. The desire for having high quality output signals from raw MCG data acquired in a simple shielded room or even in unshielded environment may be realized with the scheme.  相似文献   

15.
In ultra-low-field magnetic resonance imaging (ULF MRI), superconductive sensors are used to detect MRI signals typically in fields on the order of 10-100 μT. Despite the highly sensitive detectors, it is necessary to prepolarize the sample in a stronger magnetic field on the order of 10-100 mT, which has to be switched off rapidly in a few milliseconds before signal acquisition. In addition, external magnetic interference is commonly reduced by situating the ULF-MRI system inside a magnetically shielded room (MSR). With typical dipolar polarizing coil designs, the stray field induces strong eddy currents in the conductive layers of the MSR. These eddy currents cause significant secondary magnetic fields that may distort the spin dynamics of the sample, exceed the dynamic range of the sensors, and prevent simultaneous magnetoencephalography and MRI acquisitions. In this paper, we describe a method to design self-shielded polarizing coils for ULF MRI. The experimental results show that with a simple self-shielded polarizing coil, the magnetic fields caused by the eddy currents are largely reduced. With the presented shielding technique, ULF-MRI devices can utilize stronger and spatially broader polarizing fields than achievable with unshielded polarizing coils.  相似文献   

16.
显微红外光谱分析技术是将红外光谱仪和显微镜结合发展而来的分析技术。该技术样品处理简单,可用于微区分析和微量分析,并且能反映样品的本质特征。人参包括林下山参、园参和野山参,而我国禁止采挖野山参。因此,药典只收录了林下山参和园参。该工作使用显微红外光谱技术,结合判别分析建立了对林下山参和园参的无损识别模型。收集了20个林下山参和24个园参后,采集了其显微红外光谱。其中,33个样品被随机划分为校正集,11个为验证集。建立模型时,优化了预处理方法、主成分数、建模波段和扫描部位。最后,使用多元散射校正+Savitzky-Golay平滑的预处理方法、3932.14~669.18 cm-1的波段、4个主成分数和芦头部位建立了最优的判别分析模型,准确率达到100%。结果表明,结合判别分析的显微红外光谱技术,样品处理简单、快速、无损、有效,可用于林下山参和园参的无损识别。  相似文献   

17.
Recent experiments suggested that PdZn alloy on ZnO support is a very active and selective catalyst for methanol steam reforming (MSR). To gain insight into MSR mechanism on this catalyst, plane-wave density functional theory calculations were carried out on the initial steps of MSR on both PdZn and ZnO surfaces. Our calculations indicate that the dissociation of both methanol and water is highly activated on flat surfaces of PdZn such as (111) and (100), while the dissociation barriers can be lowered significantly by surface defects, represented here by the (221), (110), and (321) faces of PdZn. The corresponding processes on the polar Zn-terminated ZnO(0001) surfaces are found to have low or null barriers. Implications of these results for both MSR and low temperature mechanisms are discussed.  相似文献   

18.
近红外光谱法无损识别林下山参及其生长年限   总被引:1,自引:0,他引:1  
对不同生长年限的林下山参96支(其中,十五年生24支,十二年生72支)和园参177支。采集近红外光谱后,应用主成分分析-马氏距离法进行判别分析。采用原始光谱,经过预处理后,在全光谱范围内分别选择合适的主成分数,对林下山参和园参以及不同生长年限的林下山参分别建立了判别分析模型。所建立的两组模型对验证集的正确判别率均为100%。表明该方法准确可靠、快速无损,可实际用于林下山参的质量控制。  相似文献   

19.
Portal vein imaging is an important method for investigating portal venous disorders. However, the diagnostic requirements are not usually satisfied when using single imaging techniques. Diagnostic accuracy can be improved by combining different imaging techniques. Contrast agents that can be used for combined imaging modalities are needed. In this study, the feasibility of using microbubbles containing gadolinium (MCG) as contrast agents for both phase contrast imaging (PCI) and magnetic resonance imaging (MRI) are investigated. MCG were made by encapsulating sulfur hexafluoride (SF6) gas with gadolinium and lyophilized powder. Absorption contrast imaging (ACI) and PCI of MCG were performed and compared in vitro. MCG were injected into the main portal trunk of living rats. PCI and MRI were performed at 2 min and 10 min after MCG injection, respectively. PCI exploited the differences in the refractive index and visibly showed the MCG, which were not detectable by ACI. PCI could facilitate clear revelation of the MCG‐infused portal veins. The diameter of the portal veins could be determined by the largest MCG in the same portal vein. The minimum diameter of clearly detected portal veins was about 300 µm by MRI. These results indicate that MCG could enhance both PCI and MRI for imaging portal veins. The detection sensitivity of PCI and MRI could compensate for each other when using MCG contrast agents for animals.  相似文献   

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