Principle and Feasibility of Electric or Magnetic Field Deflection-Projection Based Rapid Prototyping Technique

Rapid prototype manufacturing(RPM) is a new advanced manufacturing technology, which is based on the philosophy of materials increasing of lay by lay forming. Zero adventure rapid design/manufacturing can be realized with rapid prototypes of 3D CAD of products. Rapid prototyping has been an effective tool of R&D of new products. A novel rapid prototyping and manufacturing (RP&M) technique is brought forward. The principle of the process is to form layered sections and to make the prototype or part layer by layer by deflection projection of electric charged powder granules passing through electric or magnetic field and by controllable line and field scan of the powder granule beam. The feasibility issue of the process is theoretically and experimentally investigated.It shows that deflection projection of electric charged powder granules beam passing through electric field can be significant and feasible to the rapid prototyping technique.

Impact of Polymer Coating on the Flexural Strength and Deflection Characteristics of Fiber-Reinforced Concrete Beams

Liquid polymers(LP)have become an important structural material used in the construction industry in the last decade.This paper investigates the via­bility of using commercially available LPs as a coating material to improve the flexural strength of fiber-modified concrete beams.The scope included preparing rectangular prism concrete beams with a concrete mixture includ­ing fly ash and fiber and coating them with four different liquid polymers at a uniform thickness following the curing process while one set of sam­ples was maintained under the same conditions as a control group without coating.In addition,cylindrical samples were prepared to determine the compressive strength of the concrete mixture.Following the curing process in an unconfined open-air laboratory environment for another 28 days,con­crete samples were tested to determine the flexural strength and deflection characteristics under center point loading equipment.The results revealed that all four coating types enhanced both the flexural strength and the av­erage maximum deflection of the beams compared to the control group.While the enhancement in the flexural strength changed approximately between 5%and 36%depending on the coating type,the improvements in average maximum deflections varied between 3.7%and 28.4%.

Mn掺杂ZnS(110)表面的电子结构和磁性

采用基于密度泛函理论的第一性原理方法,研究Mn掺杂ZnS(110)表面的电子结构和磁性.计算分析不同掺杂组态的几何参数、形成能、磁矩、电子态密度以及电荷密度.结果表明:单个Mn原子掺杂,替位于表面第二层的Zn原子时体系形成能最低,说明该层是最稳定的掺杂位置.对于两个Mn原子的掺杂,当Mn与Mn之间呈反铁磁耦合时体系最稳定.体系的总磁矩和自由Mn原子的磁矩差别很小,但是Mn原子的局域磁矩却依赖于Mn原子的3d态和近邻S原子的3p态的杂化作用,即受周围S原子环境的变化影响较大.此外,分析电荷密度图得出Mn原子替换Zn原子后与S原子形成了更强的共价键.

矩形波激励对纳米晶合金高频磁化过程的微观影响机理

高频变压器工作时会面临占空比变化的激励情况,由于存在磁弛豫现象,矩形波占空比能通过改变铁心用材料纳米晶合金磁化时间,影响高频变压器能否达到饱和工作点。建立纳米晶合金微磁学模型,对该模型分别施加不同占空比D的矩形波激励,并定义了磁化速率v,从磁滞损耗P_(v)、v及磁矩偏转角速度ω三方面分析D对磁化过程的影响。结果表明,D=0.5时P_(v)最小,增大或减小D,都会导致P_(v)的增加,且满足两组不同占空比和为1的矩形波激励下,材料产生的P_(v)相同。若激励磁场处在上升沿,D=0.1时的v与ω最小,D=0.9时的v与ω最大;若处在下降沿,D=0.9时的v与ω最小,D=0.1时的v与ω最大。D会影响材料磁化时间,由于磁弛豫现象,改变磁化时间可决定材料能否达到饱和磁化状态,因此存在一个临界状态,该文将其定义为临界占空比D_(c)。结果表明,当D<0.5时D_(c1)的范围应处在0.2~0.21,D>0.5时D_(c2)的范围应处在0.8~0.81,为不同工况下高频变压器工作点的选取提供了参考依据。

考虑磁畴偏转的无取向硅钢应力各向异性磁致伸缩特性模拟

无取向硅钢铁心的电磁振动是电机噪声的根本来源,采用夹件固定铁心可有效抑制其振动,但夹紧力施加不当会加剧铁心振动,原因为应力使无取向硅钢的磁畴取向发生偏转而引起磁致伸缩形变增大,形成应力各向异性。因此,为了获得准确的应力加载方法,需建立考虑磁畴偏转的无取向硅钢应力各向异性磁致伸缩模型。首先,求解自由能模型并计算能量极值点的分布,模拟无取向硅钢在磁场和应力作用下的磁畴偏转路径;其次,用磁晶各向异性能、应力各向异性能以及磁场能贡献的总和表示无磁滞磁化强度,将自由能模型与考虑磁滞的磁致伸缩模型相结合,通过无取向硅钢磁致伸缩特性测试获取模型参数并进行参数依赖性分析;最后,模拟应力与磁场作用下不同磁化方向的无取向硅钢的磁滞特性和磁致伸缩特性,通过仿真结果与实验结果的对比验证了该模型的准确性。结果表明,应力的增大会使无取向硅钢磁致伸缩应变值减小,同一应力下,磁致伸缩应变的大小会随磁化角度的增大而增大,该文所提出的应力各向异性磁致伸缩模型可以有效模拟此种变化规律。

基于配重修正的极轻型植入物磁致位移力测试方法

美国材料实验协会(American Society of Testing Materials,ASTM)F2052-21标准(对应中文标准YY/T 0987.2)规定了磁共振环境中医疗器械磁致位移力的标准测试方法,在国际上被广泛接受和应用。该方法是用细线将被测植入物悬挂于磁场中,测量悬线相对竖直方向的偏转角,从而计算磁致位移力相对重力的大小。然而,当该方法应用于极轻型植入物测试时,很难满足悬线质量小于植入物质量的1%的要求。该文提出了一种基于配重修正的极轻型植入物磁致位移力测试方法:使用质量超出待测植入物质量的1%的悬线和夹持物,按照标准方法测量偏转角度,再使用待测植入物质量在被测物总质量中的占比对偏转角度进行修正,从而获得准确的测量结果。该文对配重修正法进行了理论计算和实验验证,结果表明,所提出的配重修正法能够有效测量极轻型植入物的磁致位移力偏转角。

110°消色差磁偏系统

描述了HM 1 6医用电子直线加速器的 1 1 0°消色差磁偏系统。该系统由 3块二极磁铁构成 ,其中的 2块是极性相反的小偏转角磁铁 ,1块是 1 1 0°偏转磁铁。 3块磁铁均采用C型结构 ,全部线包串联供电。

110°偏转角定子绕线多磁极偏转系统

介绍了１１０°偏转角定子绕线的多磁极偏转系统的计算机辅助设计方法，该方法应用ＥＭＡＳ（ｅｌｅｃｔｒｏｎｉｃ－ｍａｇｎｅｔｉｃｆｉｅｌｄａｎａｌｙｓｉｓｓｙｓｔｅｍ）与表面磁荷法相结合计算磁场，应用局部法优化偏转系统，得到了会聚特性良好，具有较高偏转灵敏度的１１０°偏转角的多磁极偏转系统．

Europium isotope enrichment by magnetic deflection of a polarized atomic beam

Polarized atomic beam has found many applications in studying atomic scattering processes, producing polarized nuclei, measuring surface parameters, verifying the parity violation principle and enriching isotopes. Previous researches, however, were all concentrated on alkali atoms, no work on the production and application of the polarized beam of the multivalence-electron atoms has been reported. As an effort to extend our method of isotope enrichment by magnetic deflection of a polarized atomic beam from alkali atoms to more complicated multivalence-electron atoms, recently we produced a partially polarized europium atomic beam by a single laser optical pumping and observed obvious isotope enrichment effect through the method.

Stability and electronic structure studies of LaAlO_3/SrTiO_3 (110) heterostructures

The first-principles calculations are employed to investigate the stability, magnetic, and electrical properties of the oxide heterostructure of LaAIO3/SrTiO3 （110）. By comparing their interface energies, it is obtained that the buckled interface is more stable than the abrupt interface. This result is consistent with experimental observation. At the interface of LaAIO3/SrTiO3 （110） heterostructure, the Ti-O octahedron distortions cause the Ti tzg orbitals to split into the two- fold degenerate dxz/dyz and nondegenerate dxy orbitals. The former has higher energy than the latter. The partly filled two-fold degenerate t2g orbitals are the origin of two-dimensional electron gas, which is confined at the interface. Lattice mismatch between LaA103 and SrTiO3 leads to ferroelectric-like lattice distortions at the interface, and this is the origin of spin-splitting of Ti 3d electrons. Hence the magnetism appears at the interface of LaAIO3/SrTiO3 （110）.

Two-dimensional metallic behavior at polar MgO/BaTiO_3(110) interfaces

The first-principles calculations are employed to investigate the electrical properties of polar MgO/BaTiO3（110）interfaces. Both n-type and p-type polar interfaces show a two-dimensional metallic behavior. For the n-type polar interface,the interface Ti3d electrons are the origin of the metallic and magnetic properties. Varying the thickness of Ba TiO3 may induce an insulator–metal transition, and the critical thickness is 4 unit cells. For the p-type polar interface, holes preferentially occupy the interface O 2p y state, resulting in a conducting interface. The unbalance of the spin splitting of the O 2p states in the interface Mg O layer leads to a magnetic moment of about 0.25μB per O atom at the interface.These results further demonstrate that other polar interfaces, besides LaAlO3/SrTiO3, can show a two-dimensional metallic behavior. It is helpful to fully understand the role of polar discontinuity on the properties of the interface, which widens the field of polar-nonpolar interfaces.

Experiment of gas plasma plume deflection by magnetic control

To investigate the deflection effect of gas plasma plume controlled by magnetic field,a novel experimental scheme was presented.The Cs2CO3 catalytic ionization seeds were injected into the combustion chamber to obtain gas plasma on a high temperature magneto hydrodynamic(MHD)experiment rig.The plasma jet was deflected under the action of an external magnetic field,resulting in a thrust-vector effect.Particle image velocimetry(PIV)collected two-dimensional images of jet flow field.Through image processing and velocity vector analysis,the jet deflection angle can be obtained quantitatively.At 1800-2500 K,the jet deflection was verified experimentally under the condition of 0.45 T magnetic field strength.The results indicate that the jet deflection angle increases gradually with the increase of gas temperature,and above 2200 K,the jet deflection angle increase obviously.In the process of gas plasma jet,it is feasible to realize the jet deflection controlled by MHD by adding an external magnetic field.

110kV输变电工程电磁环境影响预测及分析评价

以上海市某110 kV输变电工程为实例,采用类比监测及理论计算的方法,预测110 kV输变电工程运行对其周围电磁环境的影响。监测及预测结果表明,在满足一定变电站建设和输电线路架线要求的前提下,110 kV输变电工程其附近的电磁环境影响符合环境保护要求。

Angle measurement technology based on magnetization vector for narrow space applications

With the wide application of laser in the field of skin plastic surgery, micro laser galvanometer scanner has made great progress in this field with its portability. However, the measurement method used to measure the deflection angle of laser galvanometer in the narrow space of scanner with high precision remains to be studied. In this paper, an angle measurement method based on magnetic field is proposed, and the effect of the shapes of permanent magnets(PMs) on the measurement is studied by theoretical and experimental study under the condition that the maximum available space for the PMs is a 10 mm side cube. An angle measuring experimental device is set up, and the contrast experiment is carried out with different PMs which are the same as simulation. The experimental results show that cylindrical PM is more suitable than other PMs, which is consistent with the simulation results, and the maximum nonlinearity error is 0.562%. This method has the advantages of small volume,non-contact measurement, small moment of inertia, good dynamic response and no external excitation for the PMs, so it has a broad application prospect in micro laser galvanometer scanner.

混凝土电杆在110kV四回直线线路中的应用

介绍了应用在110kV四回直线线路中的环形混凝土电杆的设计方法,并对其实际应用作了经济分析,结果表明,110kV直线采用四回路混凝土单杆架空线路具有较好的经济优势。

光学电流传感层叠抗外磁干扰技术研究

直通光路型磁光式光学电流传感器(magneto-optical current sensor,MOCS)因具有体积小,测量准确度高等多种优点,在智能电网中有广阔应用前景。然而,由于无法构成闭合光路,外磁场干扰一直是制约直通光路型磁光式光学电流传感器实用化的重要因素。为解决此问题,该文提出光学电流传感层叠抗外磁干扰技术。首先通过定义非连续积分路径,积分张角等概念,推导出电流位于非连续闭合路径内外时对应的磁场积分表达式,进而建立适用于含任意数量磁光传感单元、按对称多边形方式布置的MOCS所受外磁干扰分析的数学模型,提出闭合路径中心偏转模型,并得出最佳中心偏转角。在此基础上提出一种新型的层叠式MOCS结构,基本抗御传感结构外任意位置电流给MOCS带来的磁场干扰。其次,提出通用的层叠式MOCS测量误差分析方法,从理论上证明层叠式MOCS满足工程需求及标准。分别建立层叠式MOCS数值仿真模型及COMSOL有限元仿真模型。仿真结果表明,在不同干扰条件下,层叠式MOCS的测量误差均低于0.2%,证明此结构能够有效降低存在外磁干扰时MOCS的测量误差。最后,设计并搭建相应的层叠式MOCS实验平台并进行相应实验。实验结果表明,新型层叠式MOCS在多种干扰情况下其测量误差均小于0.2%,证明了所提数学模型正确性及层叠式结构应用于提高MOCS抗外磁干扰能力时的有效性。

反冲质子卡阈中子探测靶室偏转磁场设计

准确测量脉冲辐射场特征参数对研究核装置反应过程、开展核技术应用具有重要意义。为解决ICF聚变初级中子等高能中子的精确测量及面临的伴随X/γ干扰问题,研究了反冲质子高能量卡阈中子探测靶室的γ和中子灵敏度随偏转磁场的变化。首先,分析了中子探测靶室的X/γ干扰主要来源,在密封窗口处和靶腿位置分别设置清扫磁场和偏转磁场,降低探测器对X/γ和次级电子的响应。然后,详细计算了靶室灵敏度随所加磁感应强度和方向的变化。模拟结果表明:在密封窗口处设置高强度清扫磁场可一定程度降低靶室对X/γ灵敏度,在靶腿处设置偏转磁场对X/γ响应的抑制效果更好;靶腿处偏转磁场使聚乙烯靶上产生的次级电子向靶腿内侧方向偏转时效果更优;偏转磁场对中子灵敏度的影响与靶室反冲质子卡阈能量和磁场方向有关,强偏转磁场会使系统的高能中子灵敏度响应曲线发生显著变化,在应用中必须仔细考虑。最后,精细测量了探测靶室靶腿内偏转磁场的3维分布,计算了靶室中子和X/γ灵敏度随射线能量的变化。理论计算数据与CPNG-400高压倍加器14.9 MeV准单能中子灵敏度标定结果对比,相对偏差小于3%,理论值与实验结果评价在不确定度范围内一致。

网格型螺线管线圈单管逆变无线电能传输系统研究与设计

无线电能传输系统磁耦合机构发生偏移和偏转时,存在耦合系数和效率急剧下降的问题。该文面向中小功率无线充电应用,设计了一种单磁通回路网格型螺线管(GFSP)磁耦合机构,磁场均匀分布兼具抗偏移和抗偏转性能。此外针对补偿拓扑构建了一种单管逆变P#LCC-S谐振网络拓扑结构,在保留传统LCC-S补偿网络性能的同时有效简化电路结构。首先,建立磁动势模型,揭示机构不同空间位置磁场分布规律,并对机构参数进行优化;其次,建立双路P#LCC-S谐振网络电路等效模型,推导出在发射线圈激励电流恒定及输出电压恒定状态下的谐振元件参数配置条件;最后,搭建一台300 W实验样机,分别在XOY平面偏移±120 mm,Z轴偏移50~100 mm,绕Z轴偏转0°~90°范围内,样机的耦合系数保持率始终高于50%,传输效率大于80%,从而验证了所提出系统的有效性与可行性。

低频脉冲磁场对TIG搭接焊电弧及焊缝成形的影响

薄板搭接接头较其它接头焊缝成形难以控制,焊接过程中加入磁场可以有效改善焊缝成形。本文研究了外加低频脉冲纵向磁场对TIG搭接焊电弧及焊缝成形的影响。利用高速摄像机拍摄磁场作用下的TIG焊电弧,利用显微镜测量焊缝的熔宽与熔深,测定电弧轴线相对于焊枪轴线的偏转角度。结果表明,在外加脉冲纵向磁场的作用下,电弧沿着焊枪轴线发生旋转运动,并且随着脉冲频率的增加,电弧的旋转运动加快;磁场频率为100 Hz时,熔宽和熔深达到最大值,熔宽为10.87 mm,熔深为5.36 mm;电弧的偏转角度最大,偏转角为41°。

绝缘子清洗机器人静磁场分析及优化

绝缘子清洗机器人在绝缘子串上开展清洗作业时,可能会影响输电线路上的静磁场环境,导致周围静磁场产生变化,其磁场强度可能越限。因此需要开展机器人绝缘子串清洗作业的静磁场分析。针对机器人清洗110 kV输电线路上的水平悬式绝缘子情况,基于ANSYS有限元分析软件分析机器人到达绝缘子串3处位置时的静磁场强度大小以及分布情况;同时为了降低机器人对周围静磁场环境的影响,对机器人的制作材料进行了优化。静磁场分析结果表明,在110 kV输电线的输送功率为10~50 MW范围内,机器人移动到绝缘子串3处位置时的磁感应强度均达到了限值;比较了铝质材料和镀铜材料的静磁场强度,结果表明,机器人制造材料更换为磁导率相对较低的镀铜材料时,可以减少周围磁场强度的大小,缩小机器人移动到不同位置时的磁场强度相对变化量,降低机器人对输电线路电磁环境的影响。