三氮宾分子的磁性设计

采用量子化学GAUSSIAN94abinitioUHF方法和STD－3G基组设计了一系列三氮宾分子，讨论了分子的几何结构和取代基对其磁性的影响．计算结果表明，这些分子都具有铁磁性并有高自旋基态，有效交换积分值随取代基的变化而变化．其中一种具有较低的总能量和高的有效交换积分值的分子，可期望被合成．

异自旋中心三自由基分子的磁性设计

采用量子化学DFTUB3LYP方法 ,在 6 31G(d)基组水平上讨论了以 1,3,5 苯为铁磁耦合单元的异自旋中心三自由基体系 .结果表明 :对于异自旋三自由基体系 ,形成异自旋后对称性降低使部分占据的近简并轨道能级劈裂值增大 ,反铁磁耦合作用普遍增强 .由两个同自旋和一个异自旋中心构成的三自由基若保持较好的对称性 (C2v)可望表现铁磁耦合 .在通常情况下这类分子服从已有规律 :ΔEPOMO小 ,ΔED Q大 ,表现为稳定的四重态基态 ,且其稳定性与苯环 2 ,4 。

“磁性元件设计”课程思政教学改革实践

理工类专业课程开展课程思政教学设计需要深入研究技术知识与思政素材的结合点,针对不同素材采取不同的教学方法,以达到自然契合的实践目标。本文以“磁性元件设计”课程为例,对理工类专业课的课程思政教学,进行了探讨和设计。

慢工出细活——评AAD S3书架音箱

速度，绝对是我们这个时代的重要关键词之一。制造业、服装业，乃至涉及到消费行为的许许多多行业，在参与市场竞争时的一大法宝就是速度，有了它，商家不怕没有赚钱的机会。实际上，这个关键词并非如今人们的发明创造，早在上个世纪的五十年代，老福特就通过改进技术、支付高工资。

完美力学的脚踏健身车

健身车是健身房必不可少的运动器械,配合动感的旋律,在健身房挥汗如雨的骑上30-40分钟,减肥效果比跑步要好不少。Ciclotte健身车只有一个轮子,简炼的车身线条里完美融合了经典几何美学概念,整个车架完全由碳纤维制成,已经和主轮完美的融合在了一起。主轮采用了磁性设计,为驾驶者模拟完美的踏脚阻尼。把手、座椅的位置都是可调节的,下载一个对应的app就可以在“真实”的地形中骑行了。

步入微型世界

随着设计和材料的改变,继电器和开关的体积正日趋小型化。

Alloying behavior and characterization of(CoCrFeNiMn)_(90)M_(10)(M=Al,Hf)high-entropy materials fabricated by mechanical alloying

The alloying behavior and microstructures of the(CoCrFeNiMn)_(90)M_(10)(M=Al,Hf)high-entropy alloy(HEA)powders fabricated by mechanical alloying were studied.The CoCrFeNiMn)_(90)Al_(10) powders have duplex solid-solution structures.In contrast,nanocrystalline HfNi_(3) anchoring in amorphous structures is found in the(CoCrFeNiMn)_(90)Hf_(10) powders.The(CoCrFeNiMn)_(90)Al_(10) powders show better ferromagnetic behaviors,mainly explained by the facilitated motion of the magnetic domain induced by the coherent interface between duplex phases.Combined with our previous work,the rules of forming solid-solution and amorphous phase in as-milled HEA powders are preliminarily proposed.It is found that,compared with the as-cast HEA reported previously,the variation range of mixing enthalpy with atomic size difference of the solid-solution formed in as-milled HEA powders is broader.Moreover,the variation ranges between mixing enthalpy and entropy with atomic size difference of the amorphous phase in HEA powder become wider than those of high-entropy bulk metallic glass.

Discussion on dynamic reliability tolerance design technology of electromagnetic relay

Reliability tolerance design of electromagnetic relay during its design period plays an essential role in guaranteeing the consistencies of reliability and output characteristic. The reliability tolerance design can ensure that the products would work well under the influence of disturbing factors (including internal interference, external interference, and machining dispersion). Com- pared with static characteristic, dynamic characteristic of electromagnetic relay can describe its operating process better. This article researches influence of the three kinds of disturbing factors on the dynamic characteristic of electromagnetic relay based on calculating dynamic characteristic. Then, the dynamic reliability tolerance design method of electromagnetic relay is discussed considering three kinds of disturbing factors. Conclusions reached can help to assure the reliability of electromagnetic relay from the beginning of design.

Study on inverter fault-tolerant operation of PMSM DTC

This paper presents an investigation of inverter fault-tolerant operation for a permanent magnet synchronous motor （PMSM） direct torque control （DTC） system under various inverter faults. The performance of a faulty standard 6-switch inverter driven PMSM DTC system is analyzed. To avoid the loss or even disaster caused by the inverter faults, a topology-modified inverter with fault-tolerant capability is introduced, which is reconfigured as a 3-phase 4-switch inverter. The modeling of the 4-switch inverter is then analyzed and a novel DTC strategy with a unique nonlinear perpendicular flux observer and feedback compensation scheme is proposed for obtaining a continuous, disturbance-flee drive system. The simulation and experimental results demonstrate that the proposed inverter fault-tolerant PMSM DTC system is able to operate stably and continuously with acceptable static and pretty good dynamic performance.

A comparison of soft magnetic composites designed from different ferromagnetic powders and phenolic resins

Soft magnetic composites （SMCs） were prepared from three different ferromagnetic powder particles： iron powder ASC 100.29, spherical FeSi particles and vitroperm （Fe73CulNb3Si16B7） flakes. Two types of hybrid organic-inorganic phenolic resins modified with either silica nanoparticles or boron were used to design a thin insulating layer perfect- ly covering the ferromagnetic particles. Fourier transform infrared （FTIR） spectrometry confirmed an incorporation of silica or boron into the polymer matrix, which manifested itself through an improved thermal stability of the hybrid resins verified by thermogravimetric-differential scanning calorimetry （TG-DSC） analysis. The core-shell particles prepared from the ferromagnetic powder particles and the modified hybrid resins were further compacted to the cylindrical and toroidal shapes for the mechanical, electrical and magnetic testing. A uniform distribution of the resin between the ferromagnetic particles was evidenced by scanning electron microscope （SEM） analysis, which was also reflected in a rather high value of the electrical resistivity. A low porosity and extraordinary high values of mechanical hardness and flexural strength were found in SMC consisting of the iron powder and phenolic resin modified with boron. The coercive fields of the prepared samples were comparable with the commercial SMCs.

Automatic Control System for Magnetic Separators Based on PLC

To make magnetic separator more excellent in beneficiation, an advanced automatic control system for magnetic separator was designed. This paper designs automatic control system for magnetic separators, combination with PLC and technology of vary frequency. This system can wholly supervise and control the parameters of work course of magnetic separators.

An experiment discovery about gravitational force changes in materials due to temperature variation

The authors discovered in first time that the weight of materials or its gravitational force by earth related to its temperature and its ferromagnetism. An experiment was designed to elevate the temperatures of six different materials （Au, Ag, Cu, Fe, Al, Ni） up to 600 ℃and precisely measured their weights. It is found all the materials weigh about 0.33 ‰ - 0. 82 ‰ less. For example the weight of silver sample weighted by a precision electronic scale in a manner of special design decreases about 0.8 ‰, when its temperature is elevated to 600 ℃. Thus different metals＇ gravitational forces or weights are adjusted with temperature variation.

钕铁硼永磁体在磁过滤机磁回路中的应用及初次工艺试验

本文提供了用钕铁硼永磁体制造磁过滤机的磁回路的试验结果。文中叙述了通过由两块反向磁块组装的回路,进一步提高空气工作间隙中的磁感应强度的方法。研究结果表明,组装的这种磁回路的分离区域体积较大,适合工业应用。在所有的试验中,空气间隙中间的磁感应强度与间隙宽度具有相关性。应用新的磁过滤机对陶瓷悬浊液进行了分选试验。文中列举了工业试验结果。

Nonlinear Control of Magnetic Bearings

In this paper, recent results controling nonlinear systems with output tracking error constmints are applied to the design of new tracking controllers for magnetic bearings. The proposed controllers can force the rotor to track a bounded and sufficiently smooth reference trajectory asymptotically and guarantee non-contactedness betweea the rotor and the stator of the magnetic beadngs. Simulation results are included to illustrate the effectiveness of the propsed controllers.

Microstructure ＆ texture evolution and magnetic properties of high magnetic-induction 6.5% Si electrical steel thin sheet fabricated by a specially designed rolling route

Electrical steel sheets with 6.5%(mas fraction) Si with good shapes and superior magnetic inductions were successfully produced by a specially designed processing route including ingot casting, hot rolling and warm rolling both with interpass thermal treatment, and final annealing. The sheets were of 0.2 mm and 0.3 mm thick over 140 mm width. A detailed study of the microstructural and textural evolutions from the hot rolling to annealing was carried out by optical microscopy, X-ray diffraction and electron backscattered diffraction. The hot rolled sheet characterized by near-equiaxed grains was dominated by the mixture of <001>//ND fiber(λ-fiber), <110>//RD fiber(α-fiber) and <111>//ND fiber(γ-fiber) textures owing to the partial recrystallization and strain induced boundary migration(SIBM) during the hot rolling interpass thermal treatment. The static recovery and SIBM during the warm rolling interpass thermal treatment result in large and elongated warm rolling grains. The warm rolling texture is dominated by obvious λ, Goss and strong γ-fiber textures. The application of the interpass thermal treatment during hot and warm rolling significantly enhances the impact of SIBM during annealing, which is responsible for the formation of the moderate λ-fiber, some near-λ fiber texture components and the obviously weakened γ-fiber texture in the annealed sheet, leading to a higher magnetic induction compared to the commercially produced 6.5% Si steel by chemical vapor deposition(CVD).

H＆Y磁性滤镜框

这款可重复使用的滤镜框拥有磁性设计，可配合楣应滤镜架使用100mm和150mm规格滤镜。www．hy-filter．shop售价约合人民币204元起。

Effect of nanoheat stimulation mediated by magnetic nanocomposite hydrogel on the osteogenic differentiation of mesenchymal stem cells

Hyperthermia has been considered as a promising healing treatment in bone regeneration. We designed a tissue engineering hydrogel based on magnetic nanoparticles to explore the characteristics of hyperthermia for osteogenic regeneration. This nanocomposite hydrogel was successfully fabricated by incorporating magnetic Fe_3O_4 nanoparticles into chitosan/polyethylene glycol(PEG) hydrogel, which showed excellent biocompatibility and were able to easily achieve increasing temperatures under an alternative magnetic field(AMF). With uniformly dispersed nanoparticles, the composite hydrogel resulted in high viability of mesenchymal stem cells(MSCs), and the elevated temperature contributed to the highest osteogenic differentiation ability compared with direct heat treatment applied under equal temperatures. Therefore, the nanoheat stimulation method using the magnetic nanocomposite hydrogel under an AMF may be considered as an alternative candidate in bone tissue engineering regenerative applications.

Conditions for magnetic and electronic properties of ultrathin Ni–Fe hydroxide nanosheets as catalysts:a DFT+U study

The effects of cation ordering and surface compensating anions on the magnetic structure and catalytic properties of unilamellar Ni-Fe hydroxide nanosheets are studied by using the density functional theory （DFT） plus U method. Fe-segregation in the nanosheets yields magnetic domains with different spin alignments, while the surface compensating anions affect the local moments and valence states of the Fe atoms. The two conditions do not radically change the super-exchange nature of interactions between the paramagnetic metal centers, hut facilitate the formation of various magnetic superlattices in the nanosheets. The calculated free energy change of the intermediates shows that the most stable magnetic structure of Ni-Fe hydrox- ide nanosheets exhibits superior catalytic activity towards oxygen reduction/evolution reactions, which is indicative of magnetic catalyst. This is due to the cycle transition between Fe2＋ and Fe~~ ions in the reactions, which determines the sequence of cleavage of the O-H bond and the release of the OH group, controlling the rate-limiting steps of the reaction. The relationship of magnetism and catalytic activity of Ni-Fe hydroxide nanosheets is established by the valence state change of the Fe ions, which will be helpful to open the way for the design of hydroxide/layered double hydroxides （LDHs）-based magnetic catalysts.

Generating strongly basic sites on magnetic nano-stirring bars:Multifunctional integrated catalysts for transesterification reaction

Mass transfer and catalyst recovery are two crucial issues in solid base catalysis,while the cumbersome operation steps and the associated time and energy penalties are still inevitable for conventional catalysts.Achieving the technical upgrades through catalyst design is desirable but challenging because of the difficulty in satisfying diverse demands of different steps.In this work,a magnetically responsive solid base catalyst with the rod-like nanostructure was developed.The rod-like solid base catalysts are composed of Fe_(3)O_(4) cores,silica shells and calcium oxide active sites.The functions of magnetic recovery and stirring were integrated into the catalyst,which applies in both the general catalytic processes and microchannel reactors given their nanoscales.When applied to the synthesis of dimethyl carbonate by onestep transesterification of methanol and ethylene carbonate,an apparent enhancement on turnover frequency value(33.1 h^(−1))was observed for nano-stirring compared with that tested without stirring(12.1 h^(−1))within 30 min.The present catalysts may open up new avenues in the development of advanced solid base catalysts.

Design of molecule-based magnetic conductors

Enabling the use of rationally designed thin films in technological devices is a recognized goal in materials science. However, constructing such thin films using highly ordered supramolecular architectures with well-controlled size and growth direction has remained an elusive target. Here, we introduce a layer-by- layer protocol to grow hybrid thin films of molecule-based magnetic conductors comprising arachidic acid and donor bis（ethylenedioxy）tetrathiafulvalene （BEDO-TTF） as the organic component and Cu/Gd complexes as the inorganic component. The construction of layered hybrid thin films was achieved at ambient conditions by employing the Langmuir-Blodgett method, which provides good control over film thickness and packing of molecules in the monolayer. As demonstrated by X-ray diffraction, these films are crystalline with distinct organic and inorganic sublattices, where the BEDO-TTF molecular layer is interfaced with the inorganic layer. Due to the flexibility of the Langmuir-Blodgett deposition technique, this result indicates a route toward the preparation of well-ordered films with various functionalities, determined by the choice of the inorganic compound that is combined with the π-unit of BEDO-TFF. Moreover, the ability to deposit films on a variety of substrates establishes the potential for lower-cost device fabrication on inexpensive substrates.