横向电压型压力传感器的磁敏性及其消除法

横向电压型压力传感器的几何形状与霍尔器件相同因此也存在有磁敏性.本文用弱场近似的统计理论导出了非均匀掺杂薄层的霍尔电势表式,理论计算与实验结果相当一致.最后,介绍了一种实际上能完全消除磁场对压力传感器影响的方法,得到了很好的结果.     

Comparative Study of Dielectric and Magnetic Properties of Selected 3D Reticulated Ceramics and Their Same Composition Ceramic Disks

3-dimensional reticulated ceramics (3DRCs) and their same composition ceramic disks(SCCDs) were fabricated by sol-gel method, with the composition of SrO-6Fe2O3(30%), SiC(35%) and TiO2(35%), sintered at 1200℃ in N2. The dielectric and magnetic parameters of such 3DRCs and their SCCDs were measured respectively in a temperature range from room temperature to 800~C and in a frequency range from 2.6 GHz to 18 GHz. The results showed that the dielectric and magnetic loss of 3DRCs were obviously larger than those of their SCCDs in a wide rangeof temperature and the whole range of measuring frequency. The increase of dielectric loss of 3DRCs was much higher than that of magnetic loss compared to their SCCDs, which was found due to the 3D net structure extrinsic characteristics.     

Crystalline and electronic structure of Pu–Ce and Pu–Ce–Ga alloys stabilized in the δ phase

In the actinides series (which corresponds to the progressive filling of the 5f sub-shell), plutonium lies at the changeover for the behavior of the 5f electrons between the light actinides (up to Np) with delocalized 5f states, and the heavy actinides (from Am on) with localized 5f states. At this boundary, the expanded δ-phase exhibits an intermediate and thus controversial behavior of its 5f electrons. This high temperature δ-phase can be stabilized at and below room temperature by alloying with so-called deltagen solutes Ga, Al, Ce and Am. In this work, some Pu–Ce and Pu–Ce–Ga alloys were studied using several techniques (dilatometry, X-ray diffraction (XRD), extended X-ray absorption fine structure spectroscopy (EXAFS), electrical resistivity and magnetic susceptibility). It is found that the mechanism of δ-Pu stabilization is far from straightforward as both Pu 5f and Ce 4f electronic states are involved, inducing complex crystalline organization while no clear localization of the 5f states can be deduced from experimental results. Ternary Pu–Ce–Ga alloys show cooperative deltagen effects of Ce and Ga.     

永磁操动机构设计参数的调整

永磁操动机构的基本结构被确定之后,对它的运行性能进行细致地研究,对其结构参数作适当的调整,使其操作更合理。     

Magnetic Resonance Imaging of fluidized beds

This paper reviews recent developments in Magnetic Resonance Imaging (MRI) which enable it to follow particle motion in fluidized beds. Imaging with a spatial resolution of 400 μm and a temporal resolution of 1 ms is now feasible; particle velocities of order 1 m/s can be measured with good accuracy. The technique provides voidage fractions on a motion-picture basis and particle velocity fields. Limitations are: (i) the particles must contain appropriate atoms e.g. C or H; and (ii) currently the fluidized bed diameter cannot exceed 50 mm, though measurements from larger units will doubtless become available. MR studies on fluidized beds are described: results are reported for (i) air jets entering the bed (ii) bubbling and slugging beds and (iii) dispersion in a bubbling bed. The data are consistent with published measurements. Study (i) helps to resolve the longstanding puzzle about the behaviour of an air jet entering a fluidized or partly-fluidized bed, answering the question: does the entering air form bubbles or a continuous jet?     

Modelling and numerical investigation of the residual stress state in a green metal powder body

Die pressing of metal powder results in a green body. After release from the die, the green body must have enough strength to be handled, to endure transport to a sintering furnace and heating to the sintering temperature. Drilling, turning and milling, which are common operations in the green state, require a green body of high strength, with no defects and excellent mechanical properties. A plane strain finite element model is used to analyse pressing of metal powder into a rectangular bar. The powder behavior is described by a “cap” model, which is implemented as a user material subroutine in the non-linear finite element program LS-DYNA. To improve modelling of strength in the green state a new non-linear density dependent failure envelope has been used. The model is adjusted to the properties of a water atomised metal powder from Höganäs AB. To resolve the severe stress gradient at the side surface of the green body, the smallest element size was chosen to be 65 μm. The aim of this work is to numerically capture and understand the development of the residual axial stress in particular at the side surface. The influence of kinematics, friction, compacting pressure and die taper are studied. Results from the numerical study show that the thickness of the compressive stress region close to the side surface of the green body varies between 50 μm and 600 μm along the surface. Compacting pressure, “upper punch hold down” and die taper geometry all have a significant influence on the residual stress state while die wall friction has only a small influence. The numerical results are in agreement with results from X-ray and neutron diffraction measurements.     

The effect of Zn ion substitution on electromagnetic properties of low-temperature fired Z-type hexaferrite

The influence of Zn substitution on the densification, microstructure, lattice parameters and electromagnetic properties of planar Z-type hexaferrites, which have stoichiometric composition of Ba₃Co_2(10.8−x)Zn_2xCu_0.4Fe₂₄O₄₁, were investigated. The results show that the Zn²⁺ substitution has no obvious effect on the densification, but Z-type hexagonal phase can form and demonstrate typical planar anisotropic characteristics of soft magnetic materials (σ_r6.20 emu/g) in the range of x0.25. The of lattice parameters of planar a (0.588 nm) and axial c (5.25 nm) remain stable. At the certain temperatures, the sintered hexaferrites with an optimal density of about 4.62 g/cm³ show better electromagnetic properties for x=0.15 than the samples without Zn²⁺ incorporation: initial permeability of about 9.0, cut-off frequency of above 800 MHz, resisitivity of above 3.20 Ω cm and dielectric constant of less than 35.     

核磁共振岩屑分析技术的实验及应用研究

提出了一种利用核磁共振技术进行现场岩屑油层物理参数定量分析的新方法。对比分析了核磁共振岩屑与岩心分析的异同，对核磁共振现场岩屑分析的可行性进行了室内实验研究，同时给出了利用核磁共振技术确定岩屑孔隙度、渗透率等重要油层物理参数的方法，该方法利用流体在不同岩石孔隙中的弛豫特性来获得岩石物性参数；在青海油田、吉林油田、冀东油田开展了核磁共振岩屑分析技术现场应用研究，将现场核磁共振岩屑分析得到的孔隙度、渗透率等储集层参数与常规取心分析及核磁测井得到的相应结果进行了对比分析。图3表3参7     

对南华褶皱系东西部磁性显著差异的认识

本文从岩石物性，地质及航磁△Ｔ磁场等特征出发，分析证实了南华褶皱系东西部存在显著差异，综合分析了造成这种差异的三种地质因素，推测东西部岩浆并非同源，对本区今年物探工作有一定的参考意义。     

用中子粉末衍射方法研究Ho2Fe17系列化合物的磁结构

在中子三轴谱仪上用中子粉末衍射方法测定了室温下样品Ａ（Ｈｏ２Ｆｅ１３Ａｌ４Ｃ）、Ｂ（Ｈｏ２Ｆｅ１３Ｇａ４Ｃ２）、Ｃ（Ｈｏ２Ｆｅ９Ｇａ４Ａｌ４）和Ｄ（Ｈｏ２Ｆｅ９Ｇａ６Ａｌ２）的晶体结构和磁结构。衍射数据用Ｉｚｕｍｉ的Ｒｉｅｔｖｅｌｄ分析程序ＲＩＥＴＡＮ进行轮廓精修处理，确定了替代原子Ｇａ、Ａｌ和间隙原子Ｃ的占位及占位数以及磁性原子Ｈｏ、Ｆｅ的原子磁矩的大小和方向。样品Ａ、Ｂ和Ｄ显亚铁磁性，Ｃ显顺磁