超磁致伸缩换能器磁场强度建模与线圈优化分析

磁场强度是决定换能器性能的关键变量,为了提高超磁致伸缩换能器(GMA)的磁场强度和输出位移,本文提出了一种新型的弓张式发音振子结构,用COMSOL软件建立二维模型,得到超磁致伸缩材料(GMM)棒内部磁场分布情况。由于弓结构内部空间受限,对激励线圈进行优化,讨论了导线经验模型、静态电阻和电感模型的适用性,建立了线圈的平均磁场模型,以线径为决策变量,计算了正弦响应下不同线径的振幅比和相位滞后。结果表明:该模型在计算电阻和电感时的相对误差分别小于5.3%和4.1%。在预测正弦响应时,计算振幅比的误差低于6.6%(在大多数条件下低于1.8%),计算滞后相位的误差低于3.4%。较宽的导线直径对提高磁场振幅有较大的帮助,但对磁场的相位滞后性影响很小。

日影偏离度与太阳平均磁场的关联

利用西藏羊八井空气簇射阵列1990年6月至1996年8月间观测到的10TeV宇宙线的太阳阴影位置，以及相同期间的太阳表面平均磁场的数值，研究了太阳阴影的偏离度与太阳平均磁场的关系，并结合简单的理论模型对这种关系进行了计算和解释．

一次导体偏心对罗氏线圈的干扰研究

笔者通过数学计算证明,在罗氏线圈骨架尺寸理想、匝数密度均匀的前提下,一次导体偏心并不会对罗氏线圈输出精度造成影响。为此笔者在相同的生产条件下制作了12只罗氏线圈并进行了测试,结果显示,在实际生产条件下制作的罗氏线圈,有一小部分线圈受到一次导体偏心的影响较小,而大部分线圈受到影响较大。最后,笔者通过增加电磁屏蔽措施,有效降低了这种不利影响,并使得罗氏线圈的输出精度完全满足工程用电流互感器的误差限值要求。

MHD from a Microscopic Concept and Onset of Turbulence in Hartmann Flow

We derive higher order magneto-hydrodynamic （MHD） equations from a microscopic picture using pro-jection and perturbation formalism. In an application to Hartmann flow we find velocity profiles flattening towards the center at the onset of turbulence in hydrodynamic limit. Comparison with the system under the effect of a uniform magnetic field yields difference in the onset of turbulence consistent with observations, showing that the presence of magnetic field inhibits onset of instability or turbulence. The laminar-turbulent transition is demonstrated in a phase transition plot of the development in time of the relative average velocities vs. Reynolds number showing a sharp increase of the relative average velocity at the transition point as determined by the critical Reynolds number.

Phase Diagram of Transverse Spin-2 Ising Model with Longitudinal Crystal Field

The transverse spin-2 Ising ferromagnetic model with a longitudinal crystal field is studied within themean-field theory.The phase diagrams and magnetization curves are obtained by diagonalizing the Hamiltonian H_i ofthe Ising system numerically,and the first order-order phase transitions,the first order-disorder phase transitions,andthe second-order phase transitions are discussed in details.Reentrant phenomena occur when the value of the transversefield is not zero and the reentrant diagram is given.

Using MATLAB Graphics Technology to Achieve the Visualization of Electromagnetic

When teaching electromagnetic fields and waves, the application of Matlab program to make simulation of electromagnetic distribution and the transmission of waves, which dynamicly shows the propagation of waves, helps students learn electromagnetic fields and electromagnetic waves. This article focuses on simulating the dynamic process of the propagation, reflection and refraction of uniform plane wave in a different medium.

Spin Polaron in a Diluted Parabolic Magnetic Quantum Well

Theoretical investigations of spin polaron in a quantum well in the spin doping superlattice systems Cd1-xinMnxinTe/Cd1-xMnxout Te are presented in this paper. A variational procedure within the effective mass approximation is employed in the presence of magnetic field to calculate the donor ionization energy. Spin polaronic shifts are estimated using a mean field theory. The results show that the donor binding energy （i） Increases with the reduction in well sizes （ii） Decreases with the magnetic field is increased for a given well width （ill） Increases to a maximum value at 90 A and then decreases as the size of the well increases beyond 90 A and （iv） Spin polaronic shifts to the donor binding energy not only decrease in a magnetic field but also with the well width. The results are compared with the existing available literature.

10 TeV宇宙线的太阳阴影研究

利用１９９５年１０月至１９９７年９月间西藏空气簇射阵列采集到的数据，再一次观测到了１０ＴｅＶ宇宙线的太阳阴影；仔细分析了１９９０年６月至１９９７年９月间观测到的１０ＴｅＶ宇宙线的太阳阴影位置，对其位置的偏移及变化行为给出了定性的解释；结合相同时期的太阳表面平均磁场强度，进一步证实了日影偏离度与太阳平均磁场的关联；利用较为完整的宇宙线成分测量数据，对日影偏离度与太阳平均磁场强度间的定量关系作了成分上的修正．

Revisit of short-term periodicities in solar mean magnetic field

Short-term variations of the solar mean magnetic field(SMMF) were investigated through re-analyzing the data from the Wilcox Solar Observatory during the last four solar activity cycles using continuous wavelet transforms.We demonstrated the time-variable characters of short-term periods of SMMF. Our results indicate that the SMMF has main periods of about 27 and 13.5 days not only in the minimum and maximum years of each activity cycle, but also in the increase and decrease of the solar cycle. The result is partly different from the conclusion that the SMMF has dominant period of about 27 days during the solar maxima and about 13.5 days during the solar minimum years(Ye et al. in Solar Phys 279:411–418, 2012). The entire time span of SMMF was investigated and discussed further.

Effects of the Next Nearest Neighbor Hopping on Superconductivity and Antiferromagnetism of Gossamer Superconductivity

The two dimensions hole-doped t-t '-J-U model was studied based on the Gutzwiller approach and the renormalized mean-field theory.The phase diagrams of gossamer superconductors and the effects of the next-nearestneighbor hopping(t ') on superconductivity and antiferromagnetism based on the t-t '-J-U model were investigated.The results show that the qualitative feature of the phase diagrams in the t-t '-J-U model is the same as in the case of the t-J-U model.The antiferromagnetic order coexists with the d-wave superconductivity(dSC) in the underdoped region below the doping δ≈ 0.1 and is enhanced by the t '.The dSC order is slightly suppressed by t ' in the underdoped region and greatly enhanced in the overdoped region.The dSC order is pushed to a larger doping region and the coexistence region of the AF and dSC extends to higher doping.

Cobalt(Ⅱ)/manganese(Ⅱ)-based molecular metamagnets

This mini-review covers recent progress in the field of cobalt(Ⅱ)/manganese(Ⅱ)-based molecular metamagnets, which can undergo magnetic phase transitions to a state with a net magnetic moment under the stimulation of external field. We simply discuss mean field theory describing these compounds and the important role of the magnetic anisotropy. The experimental properties of the known Co(Ⅱ)/Mn(Ⅱ) metamagnets are discussed, with emphasis on the variety of means by which the metamagnetic transitions have been observed and studied.

Nuclear current and antimagnetic rotation in ^(105)Cd

The effects of the nuclear current in the antimagnetic rotation band of 105Cd have been investigated in a fully self-consistent and microscopic way by using the tilted axis cranking relativistic mean-field model.It was found that the inclusion of nuclear current leads to a higher angular momentum and thus a larger kinetic moment of inertia at a given rotational frequency.As a consequence,the B(E2) values with current are always smaller than those without current.