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针对Halbach阵列核磁共振主磁体的匀场问题,提出用拓扑优化法对主磁体进行主动垫补的方法.在使用相对密度法描述优化空间材料特性、使用连续性方法推导出拓扑优化灵敏度的基础上,用最速下降法优化垫补磁块的空间位置.数值计算结果表明,本方法能达到匀场的目的. 相似文献
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《仪表技术与传感器》2020,(2)
基于核磁共振的多相流测量,能有效克服传统多相流测量方法的局限性,是目前多相流研究领域的新方向。文中基于永磁阵列磁场理论,以磁通密度和均匀性为参数优化目标,采用COMSOL有限元软件进行Halbach磁体传感器的设计与仿真。仿真和理论分析表明,永磁源内外径比、组装块数、磁性材料是影响Halbach磁体性能的主要因素。本文针对2″油管的核磁共振多相流测量,优化和设计Halbach阵列参数,最终形成了性能优越、适用于2″油管的Halbach阵列传感器,解决了核磁共振多相流动态在线测量的重要技术问题。 相似文献
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在对磁传感器进行标定时,Maxwell线圈在磁梯度场均匀度要求高且对线圈空间尺寸有严格限制时并不适用,针对这个问题设计了一种具有高均匀度的磁梯度线圈作为磁传感器标定装置。应用内部级数法对单个轴对称线圈产生的磁场进行数理分析,进而得到其磁场梯度分布的一般特性,在此基础上计算出高均匀度磁梯度线圈的结构参数与均匀度。对线圈模型进行仿真分析并完成了磁梯度线圈装置的设计和制作。最后,根据仿真结果与实际测量得到的数据,验证了设计的正确性。 相似文献
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核磁共振成像是一种先进的影像检查方式,其广泛用于医学检查和化学检查领域。核磁共振系统主要由磁体部分、磁共振波谱仪部分及数据处理部分组成,而磁体部分主要是通过主磁体提供磁场进行工作。本文对核磁共振成像超导磁体设计方法进行了分析研究。 相似文献
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磁控溅射靶表面磁场分布与靶材刻蚀特性、薄膜沉积均匀性密切相关。为确定合适的磁控靶结构参数以改善靶材表面水平磁场分布均匀性,采用Comsol软件建立矩形平面磁控溅射靶三维模型,对靶材表面磁场分布进行模拟与分析,研究永磁体结构尺寸和磁轭尺寸对磁场分布的作用规律,得到靶材表面水平磁场分布均匀、水平磁感应强度范围合理的溅射靶结构参数。研究结果可提高磁控溅射靶磁场模拟准确性,对溅射靶结构参数的选择具有指导作用。 相似文献
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Sun LT Zhao HW Zhang ZM Wang H Ma BH Zhang XZ Li XX Feng YC Li JY Guo XH Shang Y Zhao HY 《The Review of scientific instruments》2007,78(5):053302
Two high magnetic field hexapoles for electron cyclotron resonance ion source (ECRIS) have successfully fabricated to provide sufficient radial magnetic confinement to the ECR plasma. The highest magnetic field at the inner pole tip of one of the magnets exceeds 1.5 T, with the inner diameter (i.d.)=74 mm. The other hexapole magnet provides more than 1.35 T magnetic field at the inner pole tip, and the i.d. is 84 mm. In this article, we discuss the necessity to have a good radial magnetic field confinement and the importance of a Halbach hexapole to a high performance ECRIS. The way to design a high magnetic field Halbach structure hexapole and one possible solution to the self-demagnetization problem are both discussed. Based on the above discussions, two high magnetic field hexapoles have been fabricated to be utilized on two high performance ECRISs in Lanzhou. The preliminary results obtained from the two ECR ion sources are given. 相似文献
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Sensitivity of a magnetic flowmeter relies on many factors like magnetic field strength, gap between electrodes, material properties, magnet temperature etc. For a given measuring conditions, a strong magnetic field source can produce highest sensitivity for the flowmeter. An economic design of magnetic field source would be to produce the strongest magnetic field from a given amount of magnetic material. In this paper, various magnet configurations are analyzed using FEM and the flowmeter sensitivity using such magnet configurations are compared. It is observed that magnets arranged in a Halbach fashion produce the highest sensitivity for the flowmeter using a given amount of magnetic material. The major challenge for the development of such a magnetic field source is its fabrication from its constituent magnets, combatting their huge attractive/repulsive forces (∼2500 N for our case). Therefore, a specific mechanical tool has been designed for assembling the magnetic field source and a robust assembly technique has been devised using numerical computations. The designed magnetic field source produces a peak magnetic field of 0.78 T in the pole cross section of 50 mm × 50 mm. 相似文献
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针对普通谐波齿轮传动需由电机经波发生器输入运动和动力,空间利用率低、惯性大、高速响应差的问题,提出一种由超磁致伸缩材料驱动的有源谐波电机。致动器作为谐波电机动力源及换能装置,对其磁场强度、均匀性、漏磁及空间限制等均有严格要求,据此提出分段内置式永磁结构布局,充分利用空间并改善均匀性;通过对偏置磁场和驱动磁场强度及均匀性影响因素研究,优化致动器参数;随后利用有限元法建立致动器模型并对磁场特性仿真分析;根据优化结构研制出超磁致伸缩谐波电机致动器样机,并对其输出特性试验研究。理论分析与试验结果表明,分段内置式永磁结构漏磁极小,所提出的设计理论和方法,保证了磁场强度和均匀性的同时也保证了致动器工作在准线性范围内,输出规律符合啮合要求,易于实现精准控制,为超磁致伸缩谐波电机走向实际应用奠定了基础。 相似文献
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A low cost auxiliary system consisting of He cryostat, superconducting magnet, and sample holder assembly with field probe has been constructed. The system meets the requirements of NMR on strongly paramagnetic or ordered magnetic materials, which are accurate temperature settings over a wide range, high NMR frequencies, high and accurate magnetic fields of moderate homogeneity, and exact crystal orientations in the fields. The following values are achieved: The temperature setting in the range 1.7-400 K varies less than 0.5% for 10 min, which is the typical recording time of a spectrum. The distance from the NMR oscillator to the sample is only 55 cm (wavelength of approximately 550 MHz radiation), giving a tolerable He evaporation rate of 0.35 l/h. The maximum field at 4.2 K is 43.2 kG, which can be measured with an accuracy better than +/-100 ppm. The homogeneity at maximum field over a central sphere 8 mm in diameter is 5 G. The uncertainty on the crystal orientation in the field is +/-1/2 degree. 相似文献
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针对一种新型磁力微加速度开关设计方案,建立了该开关系统的动力学方程,给出了影响开关动作的永磁力、表面接触力计算公式。采用四阶Runge-Kutta法对加速度激励下开关工作过程中永磁力、质量块与触点接触压力等参数的变化规律进行了仿真,对接触压力进行了极差分析和方差分析。选取微加速度开关的3个结构参数(悬臂梁宽度、质量块质量和永磁铁体积)作为关键因素,基于全面析因试验方法设计了该开关27种不同结构参数的水平组合,结果表明:微加速度开关3个结构参数中对接触可靠性影响大小的顺序为永磁铁体积V、悬臂梁宽度w、质量块质量m;可靠性最高的最佳结构参数水平组合为W3m3V1,即W=0.70mm、m=2.00g、V=5.38mm^3;在置信度为99%的情况下,悬臂梁宽度W、永磁铁体积V和质量块质量m对微加速度开关接触可靠性均有显著的影响。 相似文献
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Bing Tu Desheng Li Enhuai Lin Bin Luo Jian He Lezhi Ye Jiliang Liu Yuezhong Wang 《Frontiers of Mechanical Engineering in China》2010,5(4):446-449
Rotation magnetic beacons magnetic field strength is very important to drill parallel horizontal twin wells in steam assisted
gravity drainage (SAGD). This paper analyzes a small magnet with a diameter of 25.4 mm. At each end, there is a length of
12.6 mm with permanent magnet, and in the middle, there is a length of 78mm with magnetic materials. The magnetic field strength
generated by the magnetic material of 1J12, 1J50, and 1J79 is analyzed, respectively. ANSOFT software is used to simulate
the magnetic field strength generated by different magnetic materials above, which also be tested through experimental methods.
The comparison of the simulation and experimental results show that experimental and simulation results are basically consistent,
and the results can meet the specific requirements of engineering applications. 相似文献
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软启动永磁涡流联轴器的设计与参数分析 总被引:1,自引:0,他引:1
系统地介绍了永磁涡流联轴器的工作原理与特点。根据等效模型,应用法拉第电磁感应定律算出永磁联轴器的转矩。通过大量的ANSYS Maxwell 3D仿真,对永磁联轴器关键参数(磁铁尺寸、磁铁数量、铜盘厚度、气隙等)与转矩特性的关系进行了分析,为设计提供了有力的依据。应用上述分析结果,设计了一种新型结构并具有延迟启动功能的功率为7.5kW、转速为1500r/min的联轴器,样机的实验结果达到了设计要求。计算与仿真方法为该类联轴器的设计提供了参考。 相似文献