Calculation of Magnetic Field in J-TEXT with an Unsaturated Iron Core

A study of the magnetic field with an unsaturated iron core in tokamak equilibrium using a spool model is described in detail. The application of this model to the J-TEXT tokamak shows that the calculated results are in good agreement with those measured experimentally. At present this scheme is used to give the plasma configuration during J-TEXT＇s operation.

Analysis and Design of the Iron Core as the Arc Snubber in the EAST NBI System

A special winding iron-core is designed to act as the snubber for the neutral beam injection （NBI） power supply （PS） system in EAST, which will limit the fault current and energy caused by occasional sparking in the NBI ion source. 50-50 Ni-Fe is chosen as the high-frequency magnetization material for the iron-core. Equations for the snubber is derived from the design of the iron-core. The iron-loss factor and eddy-current losses are found to increase in a sample experiment at a frequency from 1 kHz to 20 kHz. A 1：10 miniature of the iron-core is tested and performs well with a fine capability.

New measurement of melting and thermal conductivity of iron close to outer core conditions

The amount of literature on both melting and thermal conductivity of iron at Earth’s core conditions is overwhelming and the discrepancies are very large.There is a broad range of experimental techniques each of which is flawed to a certain degree,which may explain the discrepancy.In this report,we present new data using a different method for determining the phase behavior and resistivity of iron in the laser-heated diamond cell by measuring the electrical resistance of both solid and liquid iron wires.The experiment avoids some of the major flaws of previous experiments,the most important of which is the detection of the onset of melting.These measurements confirm a shallow melting curve found earlier and the resistivity data imply a trend towards low thermal conductivity in the liquid outer core.

Raman Spectroscopic Core Scanning for Iron Ore Characterisation

Automated core scanning technologies for mineralogical characterisation of diamond core, drill chips pulps is now an established technique, particularly in the Australian iron ore industry, for mineral analysis in exploration and mining. Application of reflectance spectroscopy over the 400–2500 nm, visible to near-infrared wavelength range, has been used to characterise the iron ore oxide mineralogy of bedded iron deposit (BID) derived iron ores in India (Thangavelu et al., 2011) and Brazil (da Costa et al., 2009), and used to define the ore and gangue (e.g., clay) mineralogy in ironstone or channel iron deposits (CID) in the Pilbara region of Western Australia (e.g., Haest et al., 2012).

Effect of Carbon and Sulfur on Iron Melting at High Pressure:Implications for Composition and Evolution of the Planetary Terrestrial Cores

The presence of light element(s)in the Earth’s core is necessary in order to explain the observed density and velocity discrepancy for the core(Anderson and Ahrens,1994).O,Si,S,C and H were suggested as potential candidates based on cosmochemical considerations(Stevenson,1981).High-pressure experiment results,in conjunction with theoretical and cosmochemical evidences,argued that it is difficult for any one of them to account for the core

A Design Model of Core Snubber for EAST NBI

A transformer type iron core snubber, as a protective device against the stray capacitance during the breakdown in EAST, is analyzed in detail. Three kinds of topology are presented. Then with the analysis for equivalent circuit, the ranges of three key parameters, i.e., secondary side resistance, leakage inductance and snubber inductance, are determined. By con- sidering the saturation of the magnetic material, a design principle is Mso presented. A nearly 1：10 core snubber is tested. It is proved that a high permeability core with secondary resistor can restrain the discharge current effectively.

Preparation and characterization of Fe/SiO_2 core/shell nanocomposites

In a simple ethanol-water system,the magnetic α-Fe nanoparticles(with an average diameter of 10-40 nm)were prepared by reduction of Fe2 +using potassium borohydride in the presence of surfactant.Then the shell was formed by hydrolysis-condensation polymerization of tetraethylorthosilicate(TEOS)on the surface of the Fe particles.The samples were characterized by XRD,TEM,SAED,TG-DSC and VSM.The results indicate that a thin film of silica is coated on the surface of Fe particles through a Si-O-Fe bond.The coated shell of silica can effectively protect the Fe cores from being oxidized.

Formation mechanism of spheroidal carbide in ultra-low carbon ductile cast iron

The formation mechanism of the spheroidal carbide in the ultra-low carbon ductile cast iron fabricated by the metal mold casting technique was systematically investigated. The results demonstrated that the spheroidal carbide belonged to eutectic carbide and crystallized in the isolated eutectic liquid phase area. The formation process of the spheroidal carbide was related to the contact and the intersection between the primary dendrite and the secondary dendrite of austenite. The oxides of magnesium, rare earths and other elements can act as heterogeneous nucleation sites for the spheroidal carbide. It was also found that the amount of the spheroidal carbide would increase with an increase in carbon content. The cooling rate has an important influence on the spheroidal carbide under the same chemical composition condition.

Comparative Kinetics of Iron Ore Dissolution in Aqueous HCl-HNO₃System

The dissolution kinetics of the dissolution of iron ore in aqueous HCl/HNO3solution was studied. The elemental composition of the ore was carried out using the inductively coupled plasma-optical emission spectrophotometer (ICP-OES). The result showed that the iron ore contain;Fe (62.1%), O (21.7%), Cu (11.1%), Mg (2.39%), Na (1.51%), Mn (1.47%), K (0.78%), Ca (0.58%) and Zn (0.01%). It was determined that the dissolution rate increased with increased solution concentration, temperature, time and decreased particle size of the ore. The optimum conditions for effective dissolution of 88% of the iron ore were found to be 8 Mof the solution, 353 K, 100 min and ore particle size of less than 75 μm. The kinetic evaluation of the dissolution process was studied using three different shrinking core models (SCM);Film diffusion: kft =XB;interfacial chemical reaction krt =?1-(1-XB)1/3?and ash/product layer diffusion :??for spherical materials was performed. The results obtained showed that the rate determining step for the dissolution process was the product layer diffusion and therefore, the reaction followed this mechanism. The apparent activation energy (Ea) and the order of reaction were found to be 20.48 kJ/mol and 0.7 respectively.

甜玉米芯多糖铁配合物的工艺优化及体外活性

甜玉米芯多糖(SCP80)与三氯化铁共热合成了甜玉米芯多糖铁配合物(SCP),在单因素实验基础上,采用响应面法优化了SCP制备工艺。通过SEM、XRD、TG、纳米粒度及Zeta电位分析仪、UV-Vis和FTIR对SCP进行了形貌和结构表征,并测定了其体外抗氧化及降糖活性。结果表明,50 mL质量浓度为1 g/L的SCP80水溶液合成SCP的最佳合成工艺为:反应温度75℃、反应时间64.6 min、pH=8.5、m(SCP80)∶m(柠檬酸三钠)=3.64∶1。在该条件下制备的SCP中铁质量分数为27.89%±0.35%。与SCP80相比,SCP表面更光滑,粒径从43.8 nm(SCP80)增至164.0 nm,具有更好的热稳定性,更好的清除羟基自由基能力和还原能力,质量浓度为4.0 g/L的SCP对羟基自由基的清除率为57.51%;SCP对α-淀粉酶半抑制浓度(IC_(50))为(1.20±0.11) g/L,对α-葡萄糖苷酶的IC_(50)为(0.92±0.07) g/L,其体外降糖活性明显优于SCP80。

新能源驱动电机铁芯防锈包装存在问题及解决方案

针对新能源电机用铁芯储运过程中的防锈包装要求,分析电机用铁芯防锈包装现状,系统梳理当前电机用铁芯防锈包装存在问题,提出解决方案,明确电机用铁芯防锈包装未来发展趋势,为进一步提升新能源电机用铁芯防锈包装洁净度及可靠性提供参考。

一种适用于随钻核磁天线的磁芯材料

介绍了一种随钻核磁天线的铁粉芯磁芯材料,该材料具备高饱和磁通密度,并具备较低的介电损耗,并具备高绝缘强度,并在强磁环境下不产生磁致伸缩效应,较好的解决了随钻核磁测井仪探头敏感区域设计需求。

Effects of cooling rate on vermicular graphite percentage in a brake drum produced by onestep cored wire injection

In this research, a vermicular graphite cast iron brake drum was produced by cored wire injection in a one-step method. Silica sand and low-density alumina-silicate ceramic were used as molding materials in order to investigate the effect of cooling rate on percentage of vermicular graphite and mechanical properties of the brake drum casting. Several thermocouples were inserted into the casting in the desired positions to measure the temperature change. By means of one-step cored wire injection, the two residual concentrations of Mg and RE were effectively controlled in the ranges of 0.013%-0.017% and 0.019%-0.025%, respectively, which are crucial for the production of vermicular graphite cast iron and the formation of vermicular graphite. In addition, the cooling rate had a significant effect on the vermicular graphite percentage. In the case of the silica mold brake drum casting, there was an obvious difference in the cooling rate with the wall change, leading to a change in vermicular graphite percentage from 70.8% to 90%. In the low-density alumina-silicate ceramic mold casting, no obvious change in temperature was detected by the thermocouples and the percentage of the vermicular graphite was stable at 85%. Therefore, the vermicular graphite cast iron brake drum with a better combination of mechanical properties could be obtained.

一起低端换流变压器油中缓慢产生乙炔故障分析

本文作者分析了一起低端换流变压器运行中产生乙炔气体的故障,介绍了现场检查情况,分析认为铁心紧固件松动是引起故障的原因,提出了现场维修理方案并实施,最后消除了故障。

非晶合金-取向硅钢组合铁心结构设计及其磁-振动特性分析

非晶合金和取向硅钢是制作配电变压器铁心常用的两种软磁材料,各有优劣。采用非晶合金-取向硅钢组合铁心结构可以综合两者的优势。该文以非晶合金和取向硅钢铁心并排的组合结构为基础,选取组合铁心的取向硅钢占比和尺寸参数为自由变量,提出一种基于自由参数扫描法的组合铁心结构设计方法。首先,根据非晶合金-取向硅钢组合铁心结构特点,建立组合铁心的等效双非线性磁路模型;其次,采用磁路法迭代求解组合铁心的磁通密度分布,并制定组合铁心的结构设计流程;最后,根据结构设计结果制作了组合铁心的实验模型,采用实验和有限元仿真结合的方法分析了其磁-振动特性,验证了所提设计方法的准确性,并与传统纯非晶合金和纯取向硅钢铁心进行对比分析,阐述了组合铁心的优势。

一种变压器硅钢卷料精准排样的设计与实现

为提高变压器硅钢卷材纵剪利用率,本文作者讨论了一种二维下料问题,提出了一种改进型动态规划算法,可以将计算精度与计算量优化结合,使卷材排样利用率逼近最优。

核壳式球形铁基磁性磨料的制备及其抛光性能

[目的]混合式和镶嵌式磁性磨料的尺寸效应,以及磨粒出刃高度不一致所引起的抛光硬冲击问题亟待解决。[方法]将不规则铝粉与球形羰基铁粉均匀混合,通过加热扩散在接触界面生成金属间化合物并均匀分布在球形羰基铁粉表面,从而形成铁/铝核壳式球形磁性磨料,随后用它对氟化钙基片进行抛光。[结果]通过单因素试验优选出制备该核壳式铁基磁性磨料的最佳工艺参数为:反应时间4 h,反应温度770℃,Al含量质量分数12%。X射线衍射(XRD)、扫描电镜(SEM)观察、能谱(EDS)分析和磁化强度测试表明所得磁性磨料以羰基铁粉为内核,Fe Al、Fe_(3)Al、Fe_(0.4)Al_(0.6)等金属间化合物为壳,粒度符合正态分布,磨料相外壳分布均匀且出刃高度较为一致。氟化钙晶体经铁/铝核壳式磁性磨料抛光后表面变得光滑、平坦,粗糙度均方根值由初始的1.102μm下降到33 nm。[结论]所制备的核壳式球形铁基磁性磨料可用于软脆材料的磁力抛光。

非晶合金铁芯粘接-冲裁-叠压工艺研究

针对非晶合金在室温状态下冷加工性能不佳导致难以对其进行常规冲裁加工,严重限制其在电机领域的应用的问题,提出了一种粘接-冲裁-叠压工艺,以提高非晶合金的室温冲裁能力。首先,将多片非晶合金叠压粘结成具有一定厚度的坯料,然后对非晶合金坯料进行冲裁,最终将冲裁后的成品叠压成铁芯产品。试验证明,该工艺生产的非晶合金成品断面光洁,毛刺高度低于5μm,表面质量满足叠压要求,叠压后的成品满足电机铁芯的制造要求,解决了非晶合金在室温下冲裁质量较差、毛刺较高等问题。

基于电磁-热-力多物理场仿真的铁心电抗器结构参数分层优化方法研究

为了解决干式铁心电抗器多目标优化设计存在的不足,提出一种基于灵敏度分析的分层优化方法。首先,根据铁心电抗器的结构参数建立仿真模型,获得了电抗器电磁、温升和振动特性,在此基础上,基于多物理场仿真和拉丁超立方试验设计方法,结合灵敏度分析技术,得出结构参数对电抗器各性能目标的影响规律;其次,建立了铁心电抗器多目标优化模型,将优化目标与结构参数划分为2个层次,进行降维处理;最后,采用响应面法(RSM)和NSGA-Ⅱ算法分别获得了分层后最佳的铁心和绕组结构参数,并通过仿真验证优化方法的有效性。结果表明该方法能有效提高干式铁心电抗器的各项性能同时控制成本和损耗,可为铁心电抗器向质量效益型和绿色低碳型转变提供借鉴和参考。

基于COMSOL的电磁选针器性能优化

为了分析各种材料属性对电磁选针器的影响,文中利用COMSOL中的电磁仿真模块,建立电磁选针器仿真模型,分析不同永磁体材料、铁芯材料和线圈匝数对选针器动态响应过程的影响,并进行仿真。仿真结果表明,不同的永磁体剩余磁通量和矫顽力不同,剩余磁通量和矫顽力越大,其保持力矩越大,摆动到位时间越快;铁芯材料的相对磁导率越大,其保持力矩越大,摆动到位时间越快;线圈匝数越多,其保持力矩越大,摆动到位时间越快。