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目前压电加速计的磁灵敏度的测试方法采用ISO/5347-19-1993《振动与冲击传感器的校准方法磁灵敏度测试》,这种方法不能去除传感器自转产生固有振动信号的干扰,难以保证测量结果的准确性。本文分析了压电加速度传感器磁灵敏度产生原理,针对当前国际标准存在的问题,提出一种三维的压电加速度传感器磁灵敏度测试方法。利用该方法对压电加速度传感在不同磁场强度下和固定磁场下多个维度的信号输出进行测量。测量数据显示传感器磁灵敏度随磁场强度增大呈非线性增大规律,且传感器的磁灵敏度具有空间矢量。结果表明多维测试方法能够有效测量传感器磁灵敏的空间矢量,克服了传统测量方法信噪比低的缺点,减小了测量误差。 相似文献
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磁偏转质谱计是根据离子在磁分析器中运动时,不同质荷比的离子有不同的偏转半径原理来实现质量分离的。磁场大小和分布对质谱计的性能影响较大,因而设计时需要对质谱计磁场分布进行精确计算。应用有限元法建立了计算质谱计磁分析器磁场的物理模型,并利用这一模型计算了磁分析器磁感应强度在空间的分布情况。结果表明,在半径分别为20 mm和50 mm的1/4圆弧轨道上,其磁场分布规律类似。由于边缘磁场效应,在磁铁边界区域约3 mm范围内,磁感应强度基本呈直线下降,这一结果为磁分析器的结构优化和边缘场补偿提供了理论依据。 相似文献
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受扭轴类零件磁记忆信号的初步研究 总被引:2,自引:1,他引:2
金属磁记忆检测技术是通过测试构件在外载荷作用过程中形成的表面微弱磁场的变化来监测其损伤状态的。利用该技术,研究了受扭磁性轴类构件的磁记忆检测信号特征,并探讨了磁场环境对构件在扭矩作用下磁记忆信号的影响。结果表明,磁记忆检测信号与构件的损伤状态之间具有明显的相关性,磁场环境对改善金属磁记忆检测效果具有较好的作用。 相似文献
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在施加不同磁场强度及方向的稳恒磁场环境中,采用离子束溅射沉积法,在玻璃衬底上制备SmFe-B超磁致伸缩薄膜(GMF)。使用LS-7010M-KC激光微位移传感器与交变梯度磁强计(AGM)分别测试薄膜悬臂梁磁偏转量与磁滞回线,以研究制备时施加稳恒磁场对薄膜磁致伸缩性能及软磁性能的影响。利用微磁学软件OOMMF,模拟研究了在外加相同实验磁场强度下,施加不同稳恒磁场强度对Sm-Fe-B薄膜磁矩分布的影响。实验研究结果表明,施加稳恒磁场下制备的薄膜样品,其饱和磁致伸缩性能明显优于无磁场环境所制备的样品;在实验条件下,薄膜样品的磁致伸缩性能随着施加稳恒磁场强度的增大而提高。模拟与实验研究结果均表明,Sm-Fe-B GMF的易磁化轴与沉积过程中所施加的稳恒磁场方向一致。在特定的悬臂梁结构应用中,薄膜沉积过程中通过改变施加不同稳恒磁场方向与其强度大小,可获得达到所需易磁化轴方向且具有较大磁偏转量的薄膜元件。 相似文献
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蒋峰 《功能材料与器件学报》2014,(5):164-169
利用退火处理后的Co66.3Fe3.7Si12B18非晶带作为敏感元件,研制出一种基于非晶带巨磁阻抗效应的磁场测量仪。设计了传感器的信号处理电路及测量仪的硬件电路,并给出实验结果。实验表明,该测量仪能够检测-260—+260A/m范围内的微弱磁场,可应用于地球磁场、环境磁场等微弱磁场检测领域。 相似文献
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心磁检测对于心脏相关疾病的诊断具有独特优势,在用于测量心脏磁场的传感器(下称心磁传感器)的研制过程中,需要在模拟心磁的磁场环境下进行测试工作。基于此,设计了一个用于心磁传感器测试系统的亥姆赫兹线圈,它可以产生磁感应强度为pT级的动态磁场,模拟心磁环境,以满足心磁传感器测试的需求。根据亥姆赫兹线圈的磁场产生原理,使用磁屏蔽筒对环境磁场进行屏蔽,通过计算确定了线圈尺寸、线圈匝数、导线长度及导线横截面直径等参数。使用COMSOL Multiphysics仿真软件对亥姆赫兹线圈产生的静态磁场的分布均匀性以及通入线圈电流变化时磁场的动态特性进行仿真分析。仿真结果表明,所设计的亥姆赫兹线圈满足设计要求,能够产生磁场强度为100 pT左右、均匀度小于5%、波形实时性好的类心脏磁场波形,为心磁传感器的测试提供了良好的测试环境。所设计的亥姆赫兹线圈能够用于心磁传感器的测试工作,为心磁传感器的实际应用奠定了基础。 相似文献
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A feasibility study is being carried out on the operation of a SQUID gradiometer without any balancing techniques in a non-shielded environment. This paper compares empirically the performances of second and third order gradiometers; it also presents a general procedure for the design of third order gradiometers, taking into account the measured spatial dependence of the magnetic field of the human heart.The performance of a third order gradiometer is very promising for a noisy environment; it has a better low frequency noise rejection than the second order gradiometers tested, and needs no external balancing. 相似文献
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Kosuke Sato Akihiro Tsuchiya Tai Oshima Noriko Y. Yamasaki Toshimitsu Morooka 《Journal of Low Temperature Physics》2008,151(1-2):345-350
We report on the performance of two types of SQUID gradiometers developed for the readout of magnetic calorimeters. Our previously
developed low dissipation SQUID gradiometer optimized for low temperature operation has demonstrated the flux noise level
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under a magnetic field of 2.5 mT and 150 mK. With a cylindrical Au:Er paramagnetic sensor mounted inside the octagonal pickup
washer of the SQUID gradiometer, we succeeded in detecting X-ray signals. However, our achieved energy resolution was 47.2±2.1 eV
at 5.9 keV limited by the high operating temperature of 150 mK and by a magnetic field, small for that temperature, due to
the limited critical current of the field coils. Based on these results, we fabricated new arrays of SQUID gradiometer by
tuning the line width and the number of turns of the field coils and shunt resistance to realize a lower noise level and a
larger magnetic field. Furthermore, arrays of SQUID gradiometer with meander patterned pickup washer was fabricated which
provides a stronger coupling between the paramagnetic sensor and the pickup washer, and a larger magnetic field at the sensor.
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H.-C. Yang Shu-Yu Wang Chin-Hao Chen J.-T. Jeng Jau-Han Chen H.-E Horng 《Journal of Low Temperature Physics》2003,131(3-4):509-520
In the work, we studied the noise characteristics of electronic gradiometers in unshielded environments. In the off-axis electronic gradiometers for biomagnetic measurements, we optimized low frequency noise and performed two-dimensional magnetic mapping of magnetic signal from human heart. The measured magnetocardiography (MCG) signal was averaged according to the simultaneously recorded electrocardiography signal to further enhance the signal-to-noise ratio. The off-axis configuration in our gradiometer system offers the flexibility for multichannel SQUID-based MCG applications. In the study of the SQUID microscope for circuit detection in unshielded environment, we fabricated SQUIDS, considered the design of cryostat, and used the lock-in technique to examine the circuit board. We also examined the magnetic field pattern from the magnetized magnetic thin film. 相似文献
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An electronic measuring system is described, by which capabilities of balancing superconducting gradiometers can be checked at room temperature before connecting them to SQUIDs. 相似文献
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S. Brabetz R. Weidl F. Klemm L. Dörrer F. Schmidl P. Seidel 《Journal of Low Temperature Physics》1997,106(3-4):527-532
We investigated different types of high-Tc DC-SQUID gradiometers with the aim to develop an one-channel heart monitoring system for non-invasive measurements in unshielded
environment. This system could be used to obtain information about the patients condition in serial examinations and in emergency
cases fast and stable. Step-edge and bicrystal Josephson junctions were used to prepare planar galvanically coupled thin film
gradiometers and magnetometers. These sensors were used to carry out measurements in well-shielded and non-shielded environment
and we compared the different noise properties and field gradient resolutions. With different types and sizes of high-Tc DC-SQUID sensors magnetocardiograms were measured in a magnetically shielded room. The influence of antenna configurations,
SQUID parameters, and cooling conditions on the measurement of magnetocardiograms will be discussed. We investigated possibilities
to suppress the earth magnetic field (with pairs of Helmholtz coils) and for noise field compensation in unshielded environment. 相似文献
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J.E. Zimmerman 《低温学》1980,20(1):3-10
This is the third of a seven part series on the potential applications of superconductivity in space. Superconducting quantum interference devices (SQUIDs) are used in highly-sensitive magnetometers and gradiometers. They are superior to all other magnetic sensors in sensitivity, frequency response, range, and linearity. They are potentially useful for measuring low-level magnetic field variations in space, such as fluctuations in the solar wind and small- or large-scale spacial anomalies of planetary fields. They are useful also as galvanometers and amplifiers, particularly for applications requiring extreme voltage sensitivity such as, for example, low-impedance bolometer amplifiers. In connection with low-frequency sensors, superconductivity provides some adjunct devices, namely perfect magnetic shields and flux transformers, the latter being used for a number of purposes including construction of fairly elaborate gradiometer pickup-loop arrays. 相似文献
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Co-based alloys were investigated as candidates for sputtered thin-film magnetic tape media. Magnetic media on polymeric substrates having acceptable magnetic properties were obtained by applying NiAl/CrMn underlayers prior to CoCrPt deposition with a nonmagnetic CoCrTa intermediate layer. Typical sputtered tape media deposited on traditional polymeric substrates at room temperature revealed sideband modulation noise and large intergranular exchange coupling. A substantial improvement in surface roughness by utilizing smooth polymeric substrates eliminated this modulation noise and accounted for the signal dependent broad-band noise power. This suggests that transition noise is a dominant component of medium noise in sputtered tape media. Additionally, substrate bias is shown to be effective in producing grain decoupling that is necessary for good signal-to-noise ratio. 相似文献
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We present a new application of superconductive magnetic gradiometry to a geophysical problem. Changing stresses in the earth's crust produce magnetic variations through the piezomagnetic effect. Seismic wave stress fluctuations cause magnetic variations measurable by a superconductive gradiometer. Their magnitude depends both on the wave stress and on the ambient stress. Measurements repeated over time can monitor changes in the ambient stress of magnetic strata near earthquake faults. Estimates of the signal size expected from the sources used in seismic surveying show that they comfortably exceed the sensitivity limits of present-day superconductive magnetic gradiometers. A first field trial of the method, conducted in the Whipple Mountains near Parker, AZ, in November 1985, shows magnetic gradient fluctuations several pT/m in amplitude coincident with the passage of seismic waves. However, ground motion can excite mechanical resonances in the gradiometer that contaminate the signal. The field trial points the way to refinements that lead to suppression of interference from ground motion. 相似文献
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