Coupled Numerical Simulation of Electromagnetic and Flow Fields in a Magnetohydrodynamic Induction Pump

Magnetohydrodynamic(MHD)induction pumps are contactless pumps able to withstand harsh environments.The rate of fluid flow through the pump directly affects the efficiency and stability of the device.To explore the influence of induction pump settings on the related delivery speed,in this study,a numerical model for coupled electromagnetic and flow field effects is introduced and used to simulate liquid metal lithium flow in the induction pump.The effects of current intensity,frequency,coil turns and coil winding size on the velocity of the working fluid are analyzed.It is shown that the first three parameters have a significant impact,while changes in the coil turns have a negligible influence.The maximum increase in working fluid velocity within the pump for the parameter combination investigated in this paper is approximately 618%.As the frequency is increased from 20 to 60 Hz,the maximum increase in the mean flow rate of the working fluid is approximately 241%.These research findings are intended to support the design and optimization of these devices.

STUDY ON TEMPERATURE FIELD INDUCED IN HIGH FREQUENCY INDUCTION HEATING

A mathematical model was established for the temperature field developed during high frequency induction heating （HFIH） by Maxwell＇s equations. It required solving the coupled equations of the electromagnetic and temperature fields. The numerical simudation was performed using FEMLAB. The comparison of the calculations using the proposed model with experimental results showed a very good correlation. The effects of the heating parameters in high frequency induction such as the distance between the plate and the coil, the applied current, the frequency, and the turns of the coil on the temperature profiles developed in the plate were also discussed using the established model.

SIMULATION OF TEMPERATURE FIELD IN ULTRA-HIGH FREQUENCY INDUCTION HEATING AND VERIFICATION

An experimental and numerical study on the temperature field induced in the ultra-high frequency induction heating is carried out.With an aim of predicting the thermal history of the workpiece,the influence factors of temperature field,such as the induction frequency,the dimension of coil and the gap between coil and workpiece,are investigated considering temperature-dependent material properties by using FLUX 2Dsoftware.The temperature field characteristic in ultra-high induction heating is obtained and discussed.The numerical values are compared with the experimental results.A good agreement between them is observed with 7.9% errors.

Temperature field evolution and heat transfer during continual local induction cladding

The evolution of temperature field of the continual motion induction cladding and the depth of heat affected zone are studied in this study.A three-dimensional finite element model for the point type continual induction cladding is established to investigate temperature distributions of fixed and motion induction cladding modes.The novel inductor is designed for cladding of curved surfaces.The modeling reliability is verified by the temperature measurements.The influence of process parameters on the maximum temperature and the generation and transfer of heat are studied.Quantitative calculation is performed to its melting rate to verify the temperature distribution and microstructures.The results show that a good metallurgical bond can be formed between the cladding layer and substrate.The melting rate gradually falls from the top of the cladding layer to the substrate,and the grain size in the substrate gradually rises.The heat affected zone is relatively small compared to integral heating.

Mathematical Multibody Model of a Soft Mounted Induction Motor Regarding Forced Vibrations Due to Dynamic Rotor Eccentricities Considering Electromagnetic Field Damping

The paper presents a mathematical multibody model of a soft mounted induction motor with sleeve bearings regarding forced vibrations caused by dynamic rotor eccentricities considering electromagnetic field damping. The multibody model contains the mass of the stator, rotor, shaft journals and bearing housings, the electromagnetic forces with respect of electromagnetic field damping, stiffness and internal (rotating) damping of the rotor, different kinds of dynamic rotor eccentricity, stiffness and damping of the bearing housings and end shields, stiffness and damping of the oil film of the sleeve bearings and stiffness and damping of the foundation. With this multibody model, the bearing housing vibrations and the relative shaft vibrations in the sleeve bearings can be derived.

Rydberg electromagnetically induced transparency and Autler–Townes splitting in a weak radio-frequency electric field

We utilize an electromagnetically induced transparency(EIT) of a three-level cascade system involving Rydberg state in a room-temperature cell, formed with a cesium 6 S_(1/2)–6 P_(3/2)–66 S_(1/2) scheme, to investigate the Autler–Townes(AT)splitting resulting from a 15.21-GHz radio-frequency(RF) field that couples the |66 S_(1/2) → |65 P_(1/2) Rydberg transition.The radio-frequency electric field induced AT splitting, γAT, is defined as the peak-to-peak distance of an EIT-AT spectrum.The dependence of AT splitting γAT on the probe and coupling Rabi frequency, ?_p and ?_c, is investigated. It is found that the EIT-AT splitting strongly depends on the EIT linewidth that is related to the probe and coupling Rabi frequency in a weak RF-field regime. Using a narrow linewidth EIT spectrum would decrease the uncertainty of the RF field measurements.This work provides new experimental evidence for the theoretical framework in [J. Appl. Phys. 121, 233106(2017)].

Comparison of Hsps Expression after Radio-frequency Field Exposure in Three Human Glioma Cell Lines

Objective To investigate and compare the effect of radio-frequency （RF） field exposure on expression of heat shock proteins （Hsps） in three human glioma cell lines （MO54, A172, and T98）. Methods Cells were exposed to sham or 1950 MHz continuous-wave for 1 h. Specific absorption rates （SARs） were 1 and 10 W/kg. Localization and expression of Hsp27 and phosphorylated Hsp27 （（78） Ser） （p-Hsp27） were examined by immunocytochemistry. Expression levels of Hsp27, p-Hs27, and Hsp70 were determined by Western blotting. Results The Hsp27 was primarily located within the cytoplasm, p-Hsp27 in both cytoplasm and nuclei of MO54, A172, and T98 cells. RF field exposure did not affect the distribution or expression of Hsp27. In addition, Western blotting showed no significant differences in protein expression of Hsp27 or HspT0 between sham- and RF field-exposed cells at a SAR of 1 W/kg and 10 W/kg for 1 h in three cells lines. Exposure to RF field at a SAR of 10 W/kg for 1 h slightly decreased the protein level of phosphorylated Hsp27 in MO54 cells. Conclusion The 1950 MHz RF field has only little or no apparent effect on Hsp70 and Hsp27 expression in MO54, A172, and T98 cells.

Spin-polarized pairing induced by the magnetic field in the Bernal bilayer graphene

Recent experimental findings have demonstrated the occurrence of superconductivity in Bernal bilayer graphene when induced by a magnetic field.In this study,we conduct a theoretical investigation of the potential pairing symmetry within this superconducting system.By developing a theoretical model,we primarily calculate the free energy of the system with p+ip-wave parallel spin pairing,p+ip-wave anti-parallel spin pairing and d+i d-wave pairing symmetry.Our results confirm that the magnetic field is indeed essential for generating the superconductivity.We discover that the p+ip-wave parallel spin pairing leads to a lower free energy for the system.The numerical calculations of the energy band structure,zero-energy spectral function and density of states for each of the three pairing symmetries under consideration show a strong consistency with the free energy results.

Bifurcations and chaos in indirect field-oriented control of induction motors

Stability of indirect field-oriented control (IFOC) of induction motor drives is greatly influenced by estimated value of rotor time constant. By choosing estimation error of rotor time constant as bifurcation parameter, the conditions of generating Hopf bifurcation in IFOC drives are analyzed. Dynamic responses and Lyapunov exponents show that chaos and limit cycles will arise for some ranges of load torque with certain PI speed controller setting. Stable drives are required for conventional applications, but chaotic rotation can promote efficiency or improve dynamic characteristics of drives. Thus, the study may be a guideline for designing a stable system or an oscillating system.

Effects of induction heating temperature fields on 321 stainless tubes during the expansion process

Expansion is an important operation in the hot extrusion production line of seamless steel tubes, which is to produce proper hollow billets for extrusion. The billet goes through induction heating before expanded to acquire a proper temperature. In this study, the effects of three types of inhomogeneous temperature fields on 321 stainless tubes during the expansion process were simulated. The results have indicated that it was an optimum temperature filed for expansion, where the temperature varied linearly along radial direction and the temperature was lower on the inner surface. This temperature field is beneficial to improving the stability of expansion and ensuring dimensional accuracy and increasing the utilization rate of tubular billet material.

Electronic dynamic behavior in inductively coupled plasmas with radio-frequency bias

The inflexion point of electron density and effective electron temperature curves versus radio-frequency （RF） bias voltage is observed in the H mode of inductively coupled plasmas （ICPs）. The electron energy probability function （EEPF） evolves first from a Maxwellian to a Druyvesteyn-like distribution, and then to a Maxwellian distribution again as the RF bias voltage increases. This can be explained by the interaction of two distinct bias-induced mechanisms, that is： bias- induced electron heating and bias-induced ion acceleration loss and the decrease of the effective discharge volume due to the sheath expansion. Furthermore, the trend of electron density is verified by a fluid model combined with a sheath module.

Energy Distribution of Ions Incident on Radio-Frequency Biased Electrodes in External Magnetic Field

A radio-frequency （rf） plasma sheath model in an oblique magnetic field is established and the energy distribution of ions （IED） incident on the rf sheath biased electrodes is numerically investigated. The simulation results reveal that the external magnetic field can have a decisive impact on the ion flux and energy distribution of the sheath. The ion energy can be transferred between the perpendicular and parallel components under the action of a magnetic field.

Influence of Discharge Parameters on Tuned Substrate Self-Bias in an Radio-Frequency Inductively Coupled Plasma

The tuned substrate self-bias in an rf inductively coupled plasma source is controlled by means of varying the impedance of an external LC network inserted between the substrate and the ground. The influencing parameters such as the substrate axial position, different coupling coils and inserted resistance are experimentally studied. To get a better understanding of the experimental results, the axial distributions of the plasma density, electron temperature and plasma potential are measured with an rf compensated Langmuir probe; the coil rf peak-to-peak voltage is measured with a high voltage probe. As in the case of changing discharge power, it is found that continuity, instability and bi-stability of the tuned substrate bias can be obtained by means of changing the substrate axial position in the plasma source or the inserted resistance. Additionally, continuity can not transit directly into bi-stability, but evolves via instability. The inductance of the coupling coil has a substantial effect on the magnitude and the property of the tuned substrate bias.

Effects of Foods on Maturity and Spawning Induction Methods on Ovulation of Rice Field Eel Monopterus albus(Zuiew,1793)in Thua Thien Hue Province,Vietnam

Adult rice field eels with 125.52±27.99 g body weight corresponding to 44.79±5.93 cm in length were maturity cultured in a 5 m^2 cement tank without mud for three months with density 30 eels/m^2.Eel broodstocks were fed with three types of food including:sea fish(T1),commercial pellet food(T2)and mixed food—50%sea fish and 50%commercial pellet food(T3).Result showed that the maximum gonadosomatic index(GSI)of female eels fed by sea fish(2.89%±0.67%)was higher than both commercial pellet food(1.62%±0.62%)and mixed food(2.03%±0.82%)(P<0.05),while,GSI of male eels was 1.27%±0.31%,0.68%±0.23%and 1.14%±0.41%(P>0.05).Maturity rate of female fed by sea fish(88.91%±9.64%)was higher than commercial pellet food(61.12%±9.64%)(P<0.05).The maturity rate of male eels was rather low and there was not significantly different among treatments(P>0.05).Then.the eels were induced for spawning with two kinds of hormones,including T1:human chorionic ganadotropin(HCG)at 1,500 IU/kg,T2:luteinzing hormone-releasing hormone(LHRH-a)at 150μg/kg and domperidon 10 mg/kg,and T3:control without hormone.The results of spawning induction methods showed that the reproduction rate of female eels induced by LHRH-a and HCG hormones were higher than that by natural reproduction method(P<0.05).Others,the survival rate of fry eels after 5 d using natural reproduction method(92.65%±2.54%)was higher than both using LHRH-a(67.77%±1.91%)and HCG(68.65%±1.23%)hormones(P<0.05).The average diameter of eggs was 3.40-3.41 mm and the length of newly hatched eels was 1.72±0.19 cm.

Static Induction Devices with Planar Type Buried Gate

Based on the surface-gate and buried-gate structures,a novel buried-gate structure called the planar type buried-gate (PTBG) structure for static induction devices (SIDs) is proposed.An approach to realize a buried-gate type static induction transistor by conventional planar process technology is presented.Using this structure,it is successfully avoided the second epitaxy with a high degree of difficulty and the complicated mesa process in conventional buried gate.The experimental results demonstrate that this structure is desirable for application in power SIDs.Its advantages are high breakdown voltage and blocking gain.

Characteristics of Controlled Bridge Circuit and Its Application in Magnetic Field Induction Measurement

The article designs a new type of bridge circuit with a controlled source—when the resistance on the bridge arm of the controlled source bridge circuit meets the bridge balance condition, and the bridge branch contains only one Current-Controlled Current Source (CCCS), a Voltage-Controlled Current Source (VCCS), a Current-Controlled Voltage Source (CCVS), or a Voltage-Controlled Voltage Source (VCVS), the circuit is called a controlled bridge circuit, which has the characteristics of bridge balance. Due to the relationship between the controlled source and the bridge arm, the sensitivity of the components on the bridge is higher mathematically and logically. When applied to measurement, engineering, automatic control, and other fields, the controlled bridge circuit has higher control ac-curacy. Mathematical derivation and simulation results prove the correctness of the bridge balance conclusion and the special properties of this bridge when applied to the measurement field.

Magnetic field-dependent inductance properties based on magnetorheological elastomer

Magnetorheological(MR)materials are a class of smart material,whose the mechanical/rheological state can be controlled under a magnetic field.Magnetorheological materials are typically fluids,gels,or elastomers.In this study,anisotropic and isotropic magneto-rheological elastomer(MRE)samples were fabricated using a silicone rubber matrix with carbonyl iron particles as filler particles.The magnetic field-dependent inductance properties of these samples were studied using inductors specially designed for the analysis.The effect of the filler particle content,fabrication conditions,and inductance properties were characterized using a self-built system in both constant and transient magnetic fields.These factors show a significant effect on the inductance properties of the MRE inductor under an applied magnetic field.The anisotropic MRE inductor was more sensitive than the inductor based on an isotropic MRE.Owing to the presence of a constant magnetic field,the inductance value of the MRE inductor decreased with an increase in the external magnetic field.An attempt in elucidation of the mechanism is reported here.This study may enable the MRE to be widely used in practical applications such as monitoring magnetic field or detecting the filler particle content inside MR materials.

Electromagnetic characteristics of cold crucible in an induction coil for melting purpose

The electromagnetic characteristics of cold wall crucible, especially its field strength and distribution, were evaluated experimentally, in which the effects of parameters as input power and position were also discussed. The results showed that the magnetic induction intensity （B） increased with the increase of the input power. Along the radial direction inside the cold crucible, B is the strongest at the edges, and gradually attenu- ated from the edges to the center. While along the axial direction, B is the strongest at the center, and gradually attenuated from the center to the edges. Corresponding with the calculation on electromagnetic field distribution inside the coil without cold crucible, the effects of cold crucible on the electromagnetic field have been reduced by comparing measured and calculated results. However, it was also found that the value of B strength will be decreased to about 50% of its original proposition without cold crucible due to the electromagnetic shielding effect, which will be the understanding for mehing turns in cold crucible.

Trace amounts of impurities in electrolytic manganese metal by sector field inductively coupled plasma mass spectrometry

An analytical method, using sector field inductively coupled plasma mass spectrometry （SF-ICP-MS） for rapid simultaneous determination of Be, Na, Mg, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, As, Sn, Sb, Pb and Bi in electrolytic manganese metal, was described. At the beginning, the samples were decomposed by HNO3 and H2504, and then analyzed by SF-ICP-MS. Most of the spectral interferences could be avoided by measuring in different mass resolution modes. The matrix effects due to the excess of sulfuric acid and Mn were evaluated. Correction of matrix effects was conducted by using the internal standard elements. The optimum condition for the determination was investigated and discussed. The detection limit is in the range of 0.001-0.169 gg/L. The current method is applied to the determination of trace impurities in electrolytic manganese metal. And experiments show that good results can be obtained much faster, more accurately and conveniently by current method.