磁力传动潜水电泵的磁损耗

磁力传动潜水电泵能够把电机和水介质隔离开 ,解决了因漏水而损坏电机的问题 ,但由于涡流和漏磁场的影响 ,泵的功率损耗增加了 11%～ 15 % ,而且由涡流引起的发热 ,将降低永磁体的性能和泵的使用寿命。本文对磁体采用优化磁化的方法 ,获得最大的磁梯度力 ,使泵的功率损耗降低 5 %～ 10 % ,磁体体积减小 13% ,降低了涡流热 ,使该泵的寿命与同型号普通潜水电泵相比提高 8倍左右。

Application of empirical mode decomposition in early diagnosis of magnetic memory signal

In order to eliminate noise interference of metal magnetic memory signal in early diagnosis of stress concentration zones and metal defects, the empirical mode decomposition method combined with the magnetic field gradient characteristic was proposed. A compressive force periodically acting upon a casing pipe led to appreciable deformation, and magnetic signals were measured by a magnetic indicator TSC-1M-4. The raw magnetic memory signal was first decomposed into different intrinsic mode functions and a residue, and the magnetic field gradient distribution of the subsequent reconstructed signal was obtained. The experimental results show that the gradient around 350 mm represents the maximum value ignoring the marginal effect, and there is a good correlation between the real maximum field gradient and the stress concentration zone. The wavelet transform associated with envelop analysis also exhibits this gradient characteristic, indicating that the proposed method is effective for early identifying critical zones.

Magnetism and Sound Velocities of Iron Carbide （Fe3C） under Pressure

The elastic property and sound velocity of FeaC under high pressure are investigated by using the spin-polarized generalized gradient approximation within density-functional theory. It is found that the magnetic phase transition from the ground ferromagnetic （FM） state to the nonmagnetic （NM） state occurs at ～73 GPa. Based on the predicted Hugoniot of Fe3C, we calculate the sound velocities of FM-Fe3C and NM-Fe3C from elastic constants. Compared with pure iron, NM-FeaC provides a better match of compressional and shear sound velocities with the seismic data of the inner core, supporting carbon as one of the light elements in the inner core.

Gradient Microstructure of K4169 Superalloy Prepared by Low Voltage Pulsed Magnetic Field Combined with Directional Solidification

The influence of the low voltage pulsed magnetic field(LVPMF)on the microstructure transition of K4169 superalloy was investigated.The gradient microstructure of K4169 superalloy composed of columnar grains,coarse grains,and fine grains was prepared through the combined method of LVPMF with directional solidification,which provided a new approach for the preparation of superalloy with gradient microstructure.The distribution of the Lorentz force and flow field under LVPMF effect was simulated,and therefore the microstructure transition mechanism was revealed.Results show that the microstructure transition should be attributed to the coupling effects of the Lorentz force and forced convection.

A Novel Magnetic Separation Oxygen-enriched Method and the Influence of Temperature and Magnetic Field on Enrichment

A novel oxygen-enriched method is presented. Using two opposite magnetic poles of two magnets with certain distance forms a magnetic space having a field intensity gradient near its borders. When air injected into the magnetic space outflows from the magnetic space via its borders, oxygen molecules in air will experience the interception effect of the gradient magnetic field, but nitrogen molecules will outflow without hindrance. Thereby the continuous oxygen enrichment is realized. The results show that the maximum increment of oxygen concentration reaches 0.49% at 298 K when the maximum product of magnetic flux density and field intensity gradient is 563T^2/m. The enrichment level is significantly influenced by the gas temperature and the magnetic field. The maximum increment of oxygen concentration drops to 0.16% when the gas temperature rises to 343 K, and drops to 0.09% when the maximum product of magnetic flux density and gradient is reduced to 101 T^2/m from 563 T^2/m.