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 ...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.展开更多
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 t...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.展开更多
This research introduces an equivalent circuitmodel and a computational method to address complex mechanical motion issues through electromechanical analogies.The study initially refines core vibration characteristics...This research introduces an equivalent circuitmodel and a computational method to address complex mechanical motion issues through electromechanical analogies.The study initially refines core vibration characteristics using single-and multi-degree-of-freedom models,subsequently establishing equivalent circuit models for these various degrees of freedom.However,employing high degree-of-freedom models for detailed modelling of the core proves overly cumbersome.The research advocates for a distributed equivalent circuit model to more accurately represent the core's layered structure,thus facilitating enhanced core modelling.Moreover,the study formulates a mechanical wave transmission equation pertinent to the vibration of the iron core,which constitutes the foundation of the distributed mechanical vibration model.This model comprehensively assesses the impact of three critical factors on core vibration:the non-linearity of winding resistance,the elec-tromechanical coupling coefficient,and the dynamic stiffness of the core.A case study elucidates the distinct influences of each factor on vibration characteristics.Furthermore,this study derives vibration calculations from a 60-day overload ageing test conducted on a 10 kV transformer under 135℃overloadconditions.The methodology involves integrating measured compression force values and the calculated dynamic stiffness of the core into an equivalent circuit model.Subsequent analysis compares the results from the equivalent circuit model with experimental measurements.These comparisons indicate an agreement between the calculated and measured values in the time-frequency domain,thereby con-firming the accuracy of the equivalent circuit model calculations.展开更多
High-temperature superconducting(HTS)technology provides an alternative approach to achieve compact transformers.Addressing AC loss in the HTS winding is crucial for HTS transformer applications.Most numerical AC loss...High-temperature superconducting(HTS)technology provides an alternative approach to achieve compact transformers.Addressing AC loss in the HTS winding is crucial for HTS transformer applications.Most numerical AC loss studies on HTS transformers have neglected the influence of iron cores.This work carries out an AC loss study to explore the impact of an iron core on the HTS windings in a 3-phase HTS 1 MVA transformer coupled with it.AC loss simulations for the transformer winding both with and without the iron core are conducted by adopting the three-dimensional(3D)T-A homogenization method.When the iron core is incorporated,the saturation magnetic fields of iron materials,flux diverters(FDs)with different geometries,and variations in turn spacings in the LV winding composed of Roebel cables are considered to investigate their influence on the AC loss of the transformer winding.The inclusion of the iron core leads to a 1.2%increase in AC loss for the transformer winding while simulating at the rated current.We attribute this slight difference to the non-inductive winding structure of the transformer winding,where a strong magnetic field generated in the space between the LV and HV windings effectively shields the influence of the iron core.展开更多
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 whic...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.展开更多
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 exp...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).展开更多
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 equival...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.展开更多
The flux cored wires with different amounts of rare earth （RE） oxides additions for hardfacing （harden-face-welding） the workpieces of high chromium cast iron were studied in this work.The morphology of carbides i...The flux cored wires with different amounts of rare earth （RE） oxides additions for hardfacing （harden-face-welding） the workpieces of high chromium cast iron were studied in this work.The morphology of carbides in hardfacing metal was observed,and the type of the carbides was determined by optical microscopy,scanning electron microscopy （SEM）,energy dispersive spectrometer （EDS） and X-ray diffraction （XRD）.Based on the data of effect of RE on carbides morphology,the refined reason for carbide by RE oxide was discussed with the misfit theory.The results showed that,the microstructure of hardfacing metal was composed of martensite,residual austenite and M7C3 carbides.With the increasing amount of RE oxide additions,the volume fraction and roundness of the carbides were increased,however,the area and perimeter of carbides were decreased.It indicated that carbides in hardfacing metal could be refined and spheroidized by adding RE oxides in flux cored wires.展开更多
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 fo...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.展开更多
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 ...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.展开更多
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 spectrophotom...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.展开更多
基金supported by National Basic Research Program ('973'Program)of China (No.2008CB717805)
文摘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.
文摘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.
基金Science and Technology Project of State Grid Corporation of China,Grant/Award Number:5500-202113135A-0-0-00。
文摘This research introduces an equivalent circuitmodel and a computational method to address complex mechanical motion issues through electromechanical analogies.The study initially refines core vibration characteristics using single-and multi-degree-of-freedom models,subsequently establishing equivalent circuit models for these various degrees of freedom.However,employing high degree-of-freedom models for detailed modelling of the core proves overly cumbersome.The research advocates for a distributed equivalent circuit model to more accurately represent the core's layered structure,thus facilitating enhanced core modelling.Moreover,the study formulates a mechanical wave transmission equation pertinent to the vibration of the iron core,which constitutes the foundation of the distributed mechanical vibration model.This model comprehensively assesses the impact of three critical factors on core vibration:the non-linearity of winding resistance,the elec-tromechanical coupling coefficient,and the dynamic stiffness of the core.A case study elucidates the distinct influences of each factor on vibration characteristics.Furthermore,this study derives vibration calculations from a 60-day overload ageing test conducted on a 10 kV transformer under 135℃overloadconditions.The methodology involves integrating measured compression force values and the calculated dynamic stiffness of the core into an equivalent circuit model.Subsequent analysis compares the results from the equivalent circuit model with experimental measurements.These comparisons indicate an agreement between the calculated and measured values in the time-frequency domain,thereby con-firming the accuracy of the equivalent circuit model calculations.
基金New Zealand Ministry of Business,Innovation and Employment(MBIE)Strategic Science Investment Fund“Advanced Energy Technology Platforms”under contract No.RTVU2004.
文摘High-temperature superconducting(HTS)technology provides an alternative approach to achieve compact transformers.Addressing AC loss in the HTS winding is crucial for HTS transformer applications.Most numerical AC loss studies on HTS transformers have neglected the influence of iron cores.This work carries out an AC loss study to explore the impact of an iron core on the HTS windings in a 3-phase HTS 1 MVA transformer coupled with it.AC loss simulations for the transformer winding both with and without the iron core are conducted by adopting the three-dimensional(3D)T-A homogenization method.When the iron core is incorporated,the saturation magnetic fields of iron materials,flux diverters(FDs)with different geometries,and variations in turn spacings in the LV winding composed of Roebel cables are considered to investigate their influence on the AC loss of the transformer winding.The inclusion of the iron core leads to a 1.2%increase in AC loss for the transformer winding while simulating at the rated current.We attribute this slight difference to the non-inductive winding structure of the transformer winding,where a strong magnetic field generated in the space between the LV and HV windings effectively shields the influence of the iron core.
基金supported by the National Science Foundation (No. 1248553)
文摘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.
文摘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).
基金supported in part by Auxiliary Heating Project of EAST upgradein part by Ph. D foundation of State Education Ministry of China(No. 20060248012)
文摘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.
基金Project supported by One Hundred Excellent Talents of Hebei Province of China and Key Project of Science and Technology of Hebei Province (09215106D)
文摘The flux cored wires with different amounts of rare earth （RE） oxides additions for hardfacing （harden-face-welding） the workpieces of high chromium cast iron were studied in this work.The morphology of carbides in hardfacing metal was observed,and the type of the carbides was determined by optical microscopy,scanning electron microscopy （SEM）,energy dispersive spectrometer （EDS） and X-ray diffraction （XRD）.Based on the data of effect of RE on carbides morphology,the refined reason for carbide by RE oxide was discussed with the misfit theory.The results showed that,the microstructure of hardfacing metal was composed of martensite,residual austenite and M7C3 carbides.With the increasing amount of RE oxide additions,the volume fraction and roundness of the carbides were increased,however,the area and perimeter of carbides were decreased.It indicated that carbides in hardfacing metal could be refined and spheroidized by adding RE oxides in flux cored wires.
文摘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.
基金financially supported by the Hebei Province Science and Technology Support Program(No.14211007D)
文摘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.
文摘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.
