共查询到20条相似文献,搜索用时 78 毫秒
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对快速富里叶变换算法的计算进行了优化,介绍了计算优化的方法和计算效率,在各种计算机上进行计算对比,计算速度平均提高了7到10倍。 相似文献
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物理计算难就难在物理量多且关系错综复杂,而一张类似生活中交通地图的辅助工具"计算地图",能够把各个物理量的关系一览无余地呈现在计算者面前,从而很好地为物理计算导航.文章分别介绍了什么是计算地图、计算地图的作用及其导航原理分析,以及绘制计算地图时要遵循的原则. 相似文献
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The Halbach cylinder is a construction of permanent magnets used in applications such as nuclear magnetic resonance apparatus, accelerator magnets and magnetic cooling devices. In this paper the analytical expression for the magnetic vector potential, magnetic flux density and magnetic field for a two dimensional Halbach cylinder are derived. The remanent flux density of a Halbach magnet is characterized by the integer p. For a number of applications the force and torque between two concentric Halbach cylinders are important. These quantities are calculated and the force is shown to be zero except for the case where p for the inner magnet is one minus p for the outer magnet. Also the force is shown never to be balancing. The torque is shown to be zero unless the inner magnet p is equal to minus the outer magnet p. Thus there can never be a force and a torque in the same system. 相似文献
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Journal of Nanoparticle Research - A new instrument based on a magnetic force produced by an alternating magnetic field gradient, which is obtained through Maxwell coils, inside a constant field... 相似文献
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一种高温超导磁悬浮装置 总被引:1,自引:0,他引:1
本文介绍一个基于倒挂吸引式(EMS)原理的高温超导磁悬浮试验装置.这个装置由高温超导磁体、单臂梁金属导轨、位置传感器、控制电路等组成.绕制超导磁体线圈所用的是Bi-2223/Ag高温超导线材.超导磁体工作在激磁电流为3.2A时,在5mm的空气间隙中产生0.21T的磁通密度,与单臂梁金属导轨可产生72N的垂直悬浮力.通过引入压控电流源,利用常规的超前一滞后校正实现了该磁悬浮装置的稳定悬浮和鲁棒控制,在负载变化87.5%的情况下仍能实现超导磁悬浮装置的稳定悬浮.该试验装置首次验证了高温超导线圈的可控性问题,为进一步探索高温超导线圈用于磁悬浮轨道交通系统的可行性打下了基础. 相似文献
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毕延芳 《核聚变与等离子体物理》1985,(2)
聚变堆的纵场线圈通常采用无弯矩的恒张力线圈,即D形线圈,这是种尺寸巨大且场强高的纵场线圈,其受电磁力的作用机械支撑问題甚突出。 恒张力线圈的概念最初由File等人提出。最初的D形轮廓线(通常称为PrincetonD)是根据纵场场强与半径成反比(即B_θ∝1/R)的简化条件求解的,也就是假定整个环形纵场线圈沿环向连续均匀地分布。但实际上,纵场线圈总是做成分立的。因为诸如各种注入、加热和抽真空等通道需在线圈之间插入,目前的趋势是在满足等离子体外缘磁场纹波要 相似文献
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Angular dependence of vertical force and torque when magnetic dipole moves vertically above flat high-temperature superconductor 下载免费PDF全文
The interaction between a permanent magnet (PM) assumed as a magnetic dipole and a flat high-temperature superconductor (HTS) is calculated by the advanced frozen-image model. When the dipole vertically moves above the semi-infinite HTS, the general analytical expression of vertical force and that of torque are obtained for an arbitrary angle between the magnetization direction of the PM and the c axis of the HTS. The variations of the force and torque are analyzed for angle and vertical movements in both zero-field cooling (ZFC) condition and field cooling (FC) condition. It is found that the maximum vertical repulsive or attractive force has the positive or negative cosine relation with the angle. However, the maximum torque has the positive or negative sine relation. From the viewpoint of the rotational equilibrium, the orientation of the magnetic dipole with zero angle is deemed to be an unstable equilibrium point in ZFC, but the same orientation is considered as a stable equilibrium point in FC. In addition, both of the variation cycles of the maximum force and torque with the angle are π. 相似文献
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S. Bornemann J. Minár J. B. Staunton J. Honolka A. Enders K. Kern H. Ebert 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(3):529-534
We present results of magnetic torque calculations using the fully relativistic
spin-polarized Korringa-Kohn-Rostoker approach applied to small Co and Fe
clusters deposited on the Pt(111) surface. From the magnetic torque one can
derive amongst others the magnetic anisotropy energy (MAE). It was found that
this approach is numerically much more stable and also computationally less
demanding than using the magnetic force theorem that allows to calculate the
MAE directly. Although structural relaxation effects were not included our
results correspond reasonably well to recent experimental data. 相似文献
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Taylor JB 《Physical review letters》2003,91(11):115002
Ripples in the confining field may exert a torque on a rotating plasma. Time reversal symmetry implies that this torque should vanish for an ideal plasma. However, even in an apparently ideal plasma, singularities can give rise to a nonzero torque. This torque is evaluated for a simple configuration. Although the primary force is magnetic, an essential contribution arises from other nonlinear terms in the equations of motion. The net force is confined to the singular layer, in the direction of the ripple wave vector and related to the energy absorbed in the layer. 相似文献
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托卡马克聚变堆中环向磁场超导线圈的磁弹性弯曲与稳定性 总被引:1,自引:0,他引:1
本文针对托卡马克装置中超导载流磁体的磁弹性弯曲与稳定性问题,运用Biot-Savart定律和曲梁弯曲理论,给出了其环向磁场的超导载流线圈结构在自身电流产生的磁力作用下的磁弹性力学模型。所得到的控制方程反映了磁场与线圈变形之间的非线性耦合作用,全面描述了结构的轴向拉伸、绕轴扭转、面内弯曲和面外弯曲等各种变形模式。本文采用半解析半数值方法对控制方程进行了定量求解,获得了有关线圈形变和内力分布的定量结果。通过其面外弯曲变形与外加电流的非线性关系,应用Southwel图,给出了线圈在磁弹性相互作用下发生磁弹性失稳的临界电流值,并讨论了临界电流随环向磁场线圈个数变化的规律 相似文献