双盘式磁力耦合器振动噪声分析与实验研究

为了在双盘式磁力耦合器设计阶段分析振动噪声特性,优化双盘式磁力耦合器设计,提出了一种利用模态叠加原理来分析其振动噪声的方法。双盘式磁力耦合器具有高转矩密度与高效率等优势,因此逐渐发展成为煤矿机械柔性传动装置。由于双盘式磁力耦合内部的转子磁场非正弦分布以及涡电流谐波等因素影响,双盘式磁力耦合器输出转矩中不可避免的存在波动。若根据计算得出的双盘式磁力耦合器的电磁振动噪声特点,在设计时选取振动噪声小的参数进行优化组合,可在实际中降低其电磁振动及噪声,有利于减少制造成本。本文结合双盘式磁力耦合器的结构特征,提出了一种模态叠加响应法计算电磁振动噪声,建立了其电磁径向力的解析模型,并在多物理场耦合作用下分析主要电磁径向力波在工作频率内的谐波响应,最后在额定功率为55 kW双盘式磁力耦合器实验台上进行试验验证。基于麦克斯韦张量法,建立了双盘式磁力耦合器的径向电磁力解析模型,并得出0阶与10阶电磁径向力波是产生振动噪声的最主要原因;利用多物理场耦合分析法进行谐波响应NVH特性分析,结果显示0阶力波的振动加速度与形变量均大于10阶力波的振动加速度与形变量,因此双盘式磁力耦合器的电磁振动主要来源于0阶力波;在额定功率为55 kW,最高转速为1 500 r/min的双盘式磁力耦合器实验台进行振动测试,试验结果显示在1 500 r/min时,试验得出的最大振动峰值及频率约为35 m/s^2和4 950 Hz,与有限元仿真结果的误差对应为6.3%和1.1%;而当变频电机的输入转速依次增大时,振动加速度的理论值、仿真值与试验值的曲线形态较为接近,误差较小;噪声估计值与实测值的最大误差仅为8.9%,基本验证了本文所提出模态叠加法的正确性。     

磁性纳米材料处理含铀废水的研究进展

磁性纳米材料具有较强的化学稳定性、可再生回收、良好的吸附性能和易于分离等优点，在去除水溶液中的铀酰离子方面有广泛的应用前景。然而，磁性纳米材料也存在易团聚、易氧化等不足，通过表面修饰或改性等方法可改善其不足，提高其对废水中铀酰离子的去除能力，改善其吸附效果。本文通过总结近年来的相关研究资料，概括了磁性纳米材料的种类，归纳总结并比较了不同种类磁性纳米材料对含铀废水的去除能力及优势与不足，探讨了磁性纳米材料在含铀废水处理中的应用并对其机理进行了分析，阐述了磁性纳米材料去除溶液中铀酰离子的影响因素，简述了目前磁性纳米材料在处理含铀废水中有待解决的问题，并对其在分离放射性元素方面的应用前景进行了展望。     

某贫磁赤铁矿石选矿工艺试验研究

为了使某矿山贫磁赤铁矿资源得到合理的开发利用，针对现开采部位矿石的性质和可选性问题，进行了工艺矿物学和可选性试验研究。试验结果表明：采用弱磁、强磁—阴离子反浮选工艺可得到精矿铁品位68.55%、精矿产率36.41%、金属回收率79.92%、尾矿品位9.86%的较好选别指标，说明矿石的可选性较好，为该矿石的合理开发利用提供了可靠的技术依据。     

机电复合作用下发电电动机磁极连接线建模及应力分析

针对抽水蓄能机组发电电动机转子磁极连接线现有设计校核往往仅考虑单一机械应力作用,提出计及机端短路故障的机电复合作用下发电电动机磁极连接线建模及应力分析方法。首先,基于有限元方法建立某抽水蓄能机组发电电动机转子结构有限元模型,得到磁极连接线不同工况下单一机械应力结果,然后建立机端三相短路故障下发电电动机电磁场有限元模型,得到计及故障下电磁力作用的机电复合应力结果。结果表明,磁极连接线飞逸工况下承受机械应力约为额定工况时的2倍,电磁力对磁极连接线不同区域影响不均,受力方向和大小的变化规律与机械应力不同,机电复合作用下会造成磁极连接线局部应力激增。     

Magneto-rotation-fibre-reinforced thermoelastic with gravity and energy dissipation

In this article, two theories of the generalized thermoelasticity Green-Naghdi theory (of type II and III) are applied, as well as the coupled theory to study the effect of magnetic field and rotation under influence of gravity on 2D problem of a fibre-reinforced thermoelastic. The normal mode analysis is used to obtain the expressions for the temperature, displacement components and the thermal stresses distributions. The resulting formulation is applied for two different concrete problems. The first concerns the case of a punch moving across the surface of semi-infinite thermoelastic half-space subjected to appropriate boundary conditions. The second deals with a thick plate subjected to a time-dependent heat source on each face. Numerical results are illustrated graphically for each problem considered. A comparison is made with the results predicted obtained by the two theories in the presence and absence of magnetic field, rotation and gravity field.     

电工钢磁性检测方法国家标准应用问题和解决方案

通过对电工钢交流磁性检测方法现行国家标准（爱泼斯坦方圈法和标准单片法）在应用中存在的问题进行了梳理和解析，认为主要问题包括次级电压波形失真时需修正比总损耗、约定的有效磁路长度并非实际有效磁路长度以及磁性测量系统校准方法缺失等，并提出了采用数字反馈控制技术控制次级电压波形无需修正比总损耗、取向硅钢单片法测量时采用475 mm有效磁路长度以及磁性测量系统综合校准方案等一些解决方案。     

Nano and Microtechnologies for the Study of Magnetotactic Bacteria

Magnetotactic bacteria (MTB) naturally synthesize magnetic nanoparticles that are wrapped in lipid membranes. These membrane‐bound particles, which are known as magnetosomes, are characterized by their narrow size distribution, high colloidal stability, and homogenous magnetic properties. These characteristics of magnetosomes confer them with significant value as materials for biomedical and industrial applications. MTB are also a model system to study key biological questions relating to formation of bacterial organelles, metal homeostasis, biomineralization, and magnetoaerotaxis. The similar size scale of nano and microfluidic systems to MTB and ease of coupling to local magnetic fields make them especially useful to study and analyze MTB. In this Review, a summary of nano‐ and microtechnologies that are developed for purposes such as MTB sorting, genetic engineering, and motility assays is provided. The use of existing platforms that can be adapted for large‐scale MTB processing including microfluidic bioreactors is also described. As this is a relatively new field, future synergistic research directions coupling MTB, and nano‐ and microfluidics are also suggested. It is hoped that this Review could start to bridge scientific communities and jump‐start new ideas in MTB research that can be made possible with nano‐ and microfluidic technologies.     

Automatic brain tissue segmentation in MR images using hybrid atlas forest based on confidence-weighted probability matrix

The segmentation of specific tissues in an MR brain image for quantitative analysis can assist the disease diagnosis and medical research. Therefore, a robust and accurate method for automatic segmentation is necessary. Atlas-based-method is a common and effective method of automatic segmentation where an atlas refers to a pair of image consist of an intensity image and its corresponding label image. Apart from the general multi-atlas-based methods, which propagate labels through the single atlas then fuse them, we proposed a hybrid atlas forest based on confidence-weighted probability matrix to consider the atlases set as a whole and treat each voxel differently. In the framework, we first register the atlas to the image space of target and calculate the confidence of voxels in the registered atlas. Then, a confidence-weighted probability matrix is generated and it augments to the intensity image of the atlas or target for providing spatial information of the target tissue. Third, a hybrid atlas forest is trained to gather the features and correlation information among the atlases in the dataset. Finally, the segmentation of the target tissues is predicted by the trained hybrid atlas forest. The segment performance and the components efficiency of the proposed method are evaluated on the two public datasets. Based on the experiment results and quantitative comparisons, our method can gather spatial information and correlation among the atlases to obtain an accurate segmentation.     

Mutual effects of chemical reaction and thermal radiation on MHD peristaltic transport of Jeffrey nanofluids: Tumor tissues treatment

As thermal radiation is one of the fundamental means of heat transfer, therefore, this study analyzes the impacts of thermal radiation and magnetic field on the peristaltic transport of a Jeffrey nanofluid in a nonuniform asymmetric channel. Further, Two models of viscosity are debated: Model (I), in which all parameters dependent on viscosity behave as a constant (as treated before in nanofluid research); Model (II), in which these known parameters are considered to vary with the temperature of the flow. Under the condition of long wavelength and low Reynolds number, the problem is rearranged. The resulting system of partial differential equations (PNE) is solved with aid of Mathematica 11. Furthermore, the streamline graphs are presented by significance of trapping bolus phenomenon. To emphasize the quality of solutions, comparisons between the previous results and recent published results by Reddy et al. have been made and signified. The comparisons are shown in Table 1 and are found to be in good agreement. As the thermal radiation increases, the diameter of nanoparticles rises (thermal radiation is a diminishing function of temperature, and with a decrease in the temperature, the diameter of the nanoparticles increases, that is, the size of nanoparticles increases and they become more active near malignant tumor tissues). Therefore, its work as agents for radiation remedy, produce limited radiation quantities, and selectively target malignant tumor for controlled mutilation (radiotherapy of oncology). Such a model is appropriate for the transportation of physiological flows in the arteries with heat and mass transfer (blood flow models).