自动过分相地面磁感应装置(磁轨枕)的研制

为了提高轨枕的承栽性能,延长轨枕的使用寿命,特选用混凝土轨枕作为磁感应装置(磁轨枕)的基座.将原Ⅲ型混凝土轨枕进行创新改良,在安装磁体位置增加了异形刚性支撑件,并且将其与轨枕内部钢筋焊接在一起,磁感应器采用n×n×n形式矩阵磁组.并确定了刚性支撑件的制作与安装、混凝土搅拌、钢丝张拉、振动成型和蒸汽养护工序的重要控制指标.检验结果表明,磁轨枕的外观质量、外形尺寸、静载强度、混凝土的脱模强度等均符合标准要求.     

配电干线周围工频磁场的简化计算方法

重载流配电干线是建筑物内主要的工频磁场源之一。为评估建筑物内的电磁环境,有时需要定量分析配电干线周围的磁场。本文总结出单芯电缆、多芯电缆、空气绝缘母线槽和全封闭母线槽等各种建筑物配电干线周围工频磁场的简化计算方法,并通过算例比较分析了配电干线的选择对磁场水平的影响。结论:从降低周围工频磁场的角度考虑,电缆干线应尽可能采用多芯电缆,母线槽干线则宜采用全封闭母线槽。     

Magnetic and electrical properties of RCu5.1In6.9 compounds

Magnetic and electrical properties of the RCu_5.1In_6.9 compounds with R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er were investigated in the temperature range 4.2–300 K. Additionally, for the compounds of Gd, Tb and Dy exhibiting magnetic anomalies at low temperatures, the magnetization versus magnetic field up to 14 T was measured at 4.2 K. Investigated compounds follow the Curie–Weiss law with relatively small values of the paramagnetic Curie temperature and the values of effective magnetic moment being in fair agreement with the values for the free ions. The electrical resistivity exhibits metallic character. The results are discussed in terms of the differences and similarities with other rare earth intermetallics.     

Crystal field analysis of EuCl3.6H2O

Absorption and magnetic circular dichroism (MCD) spectra of polycrystalline EuCl₃.6H₂O samples were recorded between 16 000 and 36 000 cm⁻¹ at ambient temperature and at 77 K. A total of 104 crystal field transitions has been observed in the spectra. The MCD spectrum resembles the first derivative of the absorption spectrum, indicating the presence of (pseudo) A-terms. The advantage of MCD is the possibility of detecting quasi-degenerate crystal field levels, which are not resolved in the absorption spectrum. The coordination polyhedron around Eu³⁺ is a distorted square antiprism (C.N.=8). In order to make the crystal field calculations more tractable, the real C₂ symmetry of the europium site is approximated by a C_2v symmetry. The energy levels of the 4f⁶ configuration of Eu³⁺ are parametrized in terms of 20 free ion parameters and 9 B_q^k crystal field parameters. J-mixing is taken into account.     

Electron paramagnetic resonance spectra of Pr ions doped in BaMO3 (M=Ce, Zr, Sn) and SrCeO3

The isotropic electron paramagnetic resonance (EPR) spectra of powders with Pr⁴⁺ doped in BaMO₃ (M=Ce, Zr, Sn) were measured at 4.2 K. A very large hyperfine interaction with the ¹⁴¹Pr nucleus was observed. The results were analyzed based on the weak field approximation, and the g values and hyperfine coupling constants A were obtained. The measured g values are much smaller than |−10/7|, showing that the crystal field effect on the behavior of a 4f electron is large. The value of |g| decreases from 0.741 (Pr⁴⁺–BaCeO₃) to 0.583 (Pr⁴⁺–BaSnO₃), which is caused by the increase of the crystal field due to the shrinking of the lattice. In contrast, the hyperfine coupling constants are almost constant: A=0.060(1) cm⁻¹. The anisotropic EPR spectra were measured for the case of Pr⁴⁺–SrCeO₃, which indicates that the octahedral array of oxygen ions about Pr⁴⁺ is considerably distorted for this system.     

Influence of HDDR treatment on magnetic properties of TbFe2- and DyFe2-based intermetallics

Magnetic properties of TbFe₂, DyFe₂, Tb(Fe_0.8M_0.2)₂ and Dy(Fe_0.8M_0.2)₂ with M=Co, Al, Si, Ga alloys affected by the Hydrogenation-Decomposition-Desorption-Recombination processing have been studied. After hydrogen treatment the coercive force H_c grows sharply, so HDDR-powders can be used as isotropic permanent magnets with the energy product up to 26 MG Oe at T=77 K. In Dy(Fe_0.8Al_0.2)₂ at T<10 K the stepwise magnetic reversal has been observed. The HDDR-treatment increases the critical field of magnetic reversal from 11 up to 18.4 kOe at 4.2 K. It is shown that the effect of the stepwise magnetic reversal is caused by a heat release in a sample during an avalanche motion of narrow domain walls.     

Molecular semiconductors for magnetometry and oximetry: lithium phthalocyanine radical

Lithium phthalocyanine (PcLi) is an intrinsic molecular semiconductor. This radical can crystallize in various crystalline phases, x, , β, which show different properties (conductivity, magnetism, oxygen sensitivity). The x and β polymorphs may be studied on single crystals. Thin films are obtained by sublimation under vacuum on glass or oriented substrates. These films present different types of organization and crystalline structures depending on the nature of the substrate, its temperature, subsequent heating and solvent treatments, etc. The only x-form shows the following properties: (i) the presence of channels in which the dioxygen molecules can migrate; (ii) a strong overlap between consecutive PcLi molecules in a stack and a very efficient spin diffusion revealed by a very narrow EPR line. The latter is strongly broadened in the presence of oxygen. This chemically stable system is then a very good candidate for magnetometry and oximetry applications, in particular in aggressive environments. Nevertheless, these exceptional properties are not yet observed on x-form thin films.     

直流螺管式电磁铁的动特性研究

本文采用分段磁路法，对直流螺管式电磁铁进行了磁路分析，在考虑漏磁，导磁体中涡流、导磁率的非线性等因素的基础上建立了动态数学模型，讨论了结构参数对动态性能的影响，并提出了缩短电磁铁动作时间的措施。     

A pilot-scale evaluation of magnetic ion exchange treatment for removal of natural organic material and inorganic anions

The objective of this research was to evaluate a magnetic ion exchange process (MIEX) for the removal of natural organic material (NOM) and bromide on a continuous-flow pilot-scale basis under different operating conditions and raw water characteristics. The most important operating variable was the effective resin dose (ERD), which is the product of the steady-state resin concentration in the contactor and the regeneration ratio. The raw water employed in this study had a moderate concentration of ultraviolet (UV)-absorbing substances and dissolved organic carbon (DOC), and a low turbidity, alkalinity, and concentration of competing anionic species. Experiments were conducted using the ambient raw water and raw water spiked with bromide, chloride, and sulfate. Substantial removal of UV-absorbing substances and DOC was achieved at ERDs as low as 0.16mL/L. Moderate bromide removal was achieved, depending on the ERD. Increasing the sulfate concentration resulted in decreased removal of UV-absorbing substances, DOC, and bromide. Consistent results were observed between the continuous-flow pilot plant tests and batch equilibrium studies.     

一种新型轧辊裂纹检测装置

以磁为激励源进行轧辊表面及内部裂纹缺陷的检测,基于磁荷理论的裂纹数学模型的建立和神经网络的分段循环逼迫的裂纹信号定量分析,实现了裂纹无损定量检测。经在铁磁材料上模拟实验取得了满意效果。