The Mechanism of Heating Rate on the Secondary Recrystallization Evolution in Grain Oriented Silicon Steel

Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the Zener factor,the diameter and number density of precipitates of interrupted testing samples were statistically calculated.The effect of precipitate ripening on the Goss texture and magnetic property was investigated.Data indicated that the trend of Zener factor was similar under different heating rates,first increasing and then decreasing,and that the precipitate maturing was greatly inhibited as the heating rate increased.Secondary recrystallization was developed at the temperature of 1010℃when a heating rate of 5℃/h was used,resulting in Goss,Brass and{110}<227>oriented grains growing abnormally and a magnetic induction intensity of 1.90T.Furthermore,increasing the heating rate to 20℃/h would inhibit the development of undesirable oriented grains and obtain a sharp Goss texture.However,when the heating rate was extremely fast,such as 40℃/h,poor secondary recrystallization was developed with many island grains,corresponding to a decrease in magnetic induction intensity to 1.87 T.At a suitable heating rate of 20℃/h,the sharpest Goss texture and the highest magnetic induction of 1.94 T with an onset secondary recrystallization temperature of 1020℃were found among the experimental variables in this study.The heating rate affected the initial temperature of secondary recrystallization by controlling the maturation of precipitates,leading to the deviation and dispersion of Goss texture,thereby reducing the magnetic properties.

Impact of Surface Sensible Heating over the Tibetan Plateau on the Western Pacific Subtropical High: A Land–Air–Sea Interaction Perspective

The impact of surface sensible heating over the Tibetan Plateau （SHTP） on the western Pacific subtropical high （WPSH） with and without air-sea interaction was investigated in this study. Data analysis indicated that SHTP acts as a relatively independent factor in modulating the WPSH anomaly compared with ENSO events. Stronger spring SHTP is usually fol- lowed by an enhanced and westward extension of the WPSH in summer, and vice versa. Numerical experiments using both an AGCM and a CGCM confirmed that SHTP influences the large-scale circulation anomaly over the Pacific, which features a barotropic anticyclonic response over the northwestern Pacific and a cyclonic response to the south. Owing to different background circulation in spring and summer, such a response facilitates a subdued WPSH in spring but an en- hanced WPSH in summer. Moreover, the CGCM results showed that the equatorial low-level westerly at the south edge of the cyclonic anomaly brings about a warm SST anomaly （SSTA） in the equatorial central Pacific via surface warm advection. Subsequently, an atmospheric Rossby wave is stimulated to the northwest of the warm SSTA, which in turn enhances the at- mospheric dipole anomalies over the western Pacific. Therefore, the air-sea feedbacks involved tend to reinforce the effect of SHTP on the WPSH anomaly, and the role of SHTP on general circulation needs to be considered in a land-air-sea interaction framework.

IMPACT OF THE HEATING OVER SOUTH ASIA UPON THE SUBTROPICAL HIGH OVER WEST-PACIFIC

A case is reported, during which the Subtropical High over the Western Pacific (hereafter, SHWP in abbreviation) shifted northwestward and met-yu at Chaniiang River valley ended. Several numerical experiments onSHWP activity influenced by the heating over south Asia monsoon area are carried out, and the statistic significance of the results is checked. The results indicate that the enhancement of positive heating over South Asia willmotivate a wave-like series of anomaly centers, which propagate northeastward from the maximum heating center.so that a strong positive potential height anomaly center will set up from North China to Japan at Day X resultingin the enhancement of SHWP. Comparison of the influence upon SHWP by the heating over south Asia monsoonarea with that over ITCZ area south to SHWP is also carried out. It is pointed out that the heating over South Asiamonsoon area tends to favor SHWP north\vard movement while the heating over ITCZ area tends to thvor SHWPwestward stretching. As for the time to begin to influence on SHWP, the heating over south Asia monsoon areafavors the enhancement of SHWP atter Day 3 while that over ITCZ south to SHWP effects atter Day 5.

RELATIONSHIPS BETWEEN THE POSITION VARIATION OF THE WEST PACIFIC SUBTROPICAL HIGH AND THE DIABATIC HEATING DURING PERSISTENT INTENSE RAIN EVENTS IN YANGTZE-HUAIHE RIVERS BASIN

By using NCEP/NCAR daily reanalysis data and daily precipitation data of 740 stations in China, relationships between the position variation of the West Pacific subtropical high (WPSH) and the diabatic heating during persistent and intense rains in the Yangtze-Huaihe Rivers basin are studied. The results show that the position variation of WPSH is closely associated with the diabatic heating. There are strong apparent heating sources and moisture sinks in both the basin (to the north of WPSH) and the north of Bay of Bengal (to the west of WPSH) during persistent and intense rain events. In the basin, Q 1z begins to increase 3 days ahead of intense rainfall, maximizes 2 days later and then reduces gradually, but it changes little after precipitation ends, thus preventing the WPSH from moving northward. In the north of Bay of Bengal, 2 days ahead of strong rainfall over the basin, Q 1z starts to increase and peaks 1 day after the rain occurs, leading to the westward extension of WPSH. Afterwards, Q 1z begins declining and the WPSH makes its eastward retreat accordingly. Based on the complete vertical vorticity equation, in mid-troposphere, the vertical variation of heating in the basin is favorable to the increase of cyclonic vorticity north of WPSH, which counteracts the northward movement of WPSH and favors the persistence of rainbands over the basin. The vertical variation of heating in the north of Bay of Bengal is in favor of the increase of anti-cyclonic vorticity to the west of WPSH, which induces the westward extension of WPSH.

Simulation of goaf heating law and the fire cooling effect during methane drainage in high level laneway

For spontaneous combustion possibilities under large flux methane drainage in the goal, dynamic permeability in combination with the Forchheimer nonlinear equation was used to solve the problem of 3D oxygen distribution, heating law in goaf and to forecast the effects of fire protection by taking the fifth section face of the No. 18 coal seam in Nanshan Coal Mine as the basis for this study. The results demonstrate that if the vertical position of the drainage laneway is so low as to cause serious air leakage, a high oxygen concentration area exists in the return side of the goaf, and there is also a high temperature region which has faster heating rate than in the other areas. The effect of methane drainage on goal heating can be alleviated dramatically by simultaneous plugging and nitrogen injection. The results show that gas data in the return side of the goaf must be detected carefully in the work face, which is of similar drainage arrangement. Therefore, comprehensive fire protection measures should be carried out if conditions permit.

Zero-voltage switching converter absorbing parasitic parameters for super high frequency induction heating

This paper presents a novel mega-Hz-level super high frequency zero-voltage soft-switching converter for induction heating power supplies. The prominent advantage of this topology is that it can absorb both inductive and capacitive parasitic components in the converter. The switch devices operate in a zero-voltage soft-switching mode. Consequently, the high voltage and high current spikes caused by parasitic inductors or capacitors oscillation do not occur in this circuit, and the high power loss caused by high frequency switching can be greatly reduced. A large value inductor is adopted between the input capacitor and the switches, thus, this novel converter shares the benefits of both voltage-type and current-type circuits simultaneously, and there are no needs of dead time between two switches. The working principles in different modes are introduced. Results of simulation and experiments operated at around 1 MHz frequency verify the validity of parasitic components absorption and show that this convener is competent for super high frequency applications.

Effect of laser heating on the microstructure and hardness of TRIP590advanced high strength steel used for roll forming

TRIP590 advanced high strength steel sheets were heated by laser with different powers.Changes of the microstructure and the hardness of TRIP590 steel under laser heating with different powers were investigated by metallographic microscope,scanning electron microscope,and hardness tester.The purpose was to study the effect of laser power on microstructure and hardness of TRIP590 steel.It is shown that the power of laser plays an important role on the microstructure and hardness of heated steel sheets.The results are helpful to determine suitable power for the laser auxiliary forming of Trip590 steel in order to obtain uniform microstructure and high hardness.

NUMERICAL EXPERIMENT OF MEDIUM-RANGE CHANGE OF THE SUBTROPICAL HIGH Ⅰ.THE INFLUENCE OF THE HEATINGSOURCE OVER TIBET PLATEAU

The medium-range change of the subtropical high of June 1979 and its influences of the heating sources over Tibet Plateau are studied by using a global circulation spectrum-model. The analyses of the simulation results show that the heating sources over Tibet Plateau play an important role in the process of frontogenesis. the intensity of frontal zone and the upper-tropospheric westerly jet associated with it. When there are heating sources over Tibet Plateau. both the frontal zone and westerly jet are stronger. There are very important mutual relations between the sensible heating and latent heating. After the sensible heating and latent heating are isolated.it departs much from reality that the significance of them are

Analysis of heating effect on the process of high deposition rate microcrystalline silicon

A possible heating effect on the process of high deposition rate microcrystalline silicon has been studied. It includes the discharge time-accumulating heating effect, discharge power, inter-electrode distance, and total gas flow rate induced heating effect. It is found that the heating effects mentioned above are in some ways quite similar to and in other ways very different from each other. However, all of them will directly or indirectly cause the increase of the substrate surface temperature during the process of depositing microcrystalline silicon thin films, which will affect the properties of the materials with increasing time. This phenomenon is very serious for the high deposition rate of microcrystalline silicon thin films because of the high input power and the relatively small inter-electrode distance needed. Through analysis of the heating effects occurring in the process of depositing microcrystalline silicon, it is proposed that the discharge power and the heating temperature should be as low as possible, and the total gas flow rate and the inter-electrode distance should be suitable so that device-grade high quality deposition rate microcrystalline silicon thin films can be fabricated.

NUMERICAL EXPERIMENT OF MEDIUM-RANGE CHANGE OF THE SUBTROPICAL HIGH Ⅱ. THE INFLUENCE OF THE HEATINGSOURCE OVER WESTERN TROPICAL PACIFIC

Numerical experiments are carried out using a global spectral model to study the role of an ideal heating source over the western tropical Pacific region in a medium-term weather process that marks the western advancement of the subtropical high in mid-June 1979. The result has indicated that the effect of the ideal heating source is evident in about 4 days after the inclusion in the high and the circulation at mid-and high-latitudes over the eastern part of China; the disturbance produced over the tropical ocean first transfers towards the northwest along the easterly flow on the southern edge of the subtropical high and then divides into two branches as it moves over the westerly over the mid-latitude area, one continuing the journey northwestward and the other turning to the northeast by east, resulting in changes in the subtropical high and the westerly through combined action.

SUBTROPICAL HIGH, LATENT HEATING BY CONVECTION AND ASSOCIATION WITH DISSIPATION AND MAINTENANCE OF SOUTH CHINA SEA TYPHOONS

Numerical modeling and experiments are conducted for the South China Sea typhoons Helen (1995) and Willie (1996) with an auto-adaptive mesh model. It is shown that durating the stage of dissipation the typhoons are mainly related with the subtropical high rather than the topography. The high is sensitive to the intensity change of the typhoon so that the former weakens as the latter strengthens and vice versa. Maintaining the typhoon as a main factor, the release of latent heat is in reversed proportion with the subtropical high in terms of the intensity. It is found that the storm tends to be maintained if it moves close to the westerly trough after landfall.

Influence of rapid heating process on the microstructure and tensile properties of high-strength ferrite–martensite dual-phase steel

Three low-carbon dual-phase （DP） steels with almost constant martensite contents of 20vo1% were produced by intercritical annealing at different heating rates and soaking temperatures. Microstructures prepared at low temperature （1043 K, FH1） with fast-heating （300 K/s） show banded ferrite/martensite structure, whereas those soaked at high temperature （1103 K, FH2） with fast heating reveal blocky martensite uniformly distributed in the fine-grained ferrite matrix. Their mechanical properties were tested under tensile conditions and compared to a slow-heated （5 K/s） reference material （SH0）. The tensile tests indicate that for a given martensite volume fraction, the yield strength and total elongation values are noticeably affected by the refinement of ferrite grains and the martensite morphology. Metallographic observations reveal the formation of microvoids at the ferrite/martensite interface in the SH0 and FH2 samples, whereas microvoids nucleate via the fracture of banded martensite particles in the FH1 specimen. In addition, analyses of the work-hardening behaviors of the DP microstructures using the differential Crussard-Jaoul technique demonstrate two stages of work hardening for all samples.

Reduction of Dislocation Densities of Ge Layers Grown on Si Substrates by Using Microwave Plasma Heating and Fabrication of High Hole Mobility MOSFETs on Ge Layers

We have developed a microwave plasma heating technique to rapidly heat the transition metal. W/SiO2 layers were deposited on Ge/Si heterostructures. By heating the W, dislocations in Ge layers originated from lattice mismatch between Ge and Si crystals were reduced drastically. We have fabricated p- MOSFETs on Ge/Si substrates and realized higher mobility of about 380 cm2/ Vs than that of Si p-MOSFET.

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.

Heating and Life Problem of High Power Density Induction Motor

An induction motor with its speed modulated by frequency features wide transfer speed range, high systematie efficiency, simple structure and long life, and it therefore becomes one of the best driving motors used in electrical vehicles. The present research trend of it is high power, high speed, high efficiency and long life. How to meet the above requirements by using the electromagnetic design, structure design and beat design, becomes a matter that needs to be resolved now. In this paper, the characters of the motor in operation are analyzed, all kinds of factors that relate to life are laid out, its heating and loss are discussed and analyzed. The key reasons affecting the motor life are presented, and different characters of a high induction motor are compared with these of a general induction motor. A design idea is described, that is : we should consider how to improve the efficiency and reliability as well as bow to reduce the heating by changing the electromagnet, structure, dissipation and operation of the motor. How to reduce its losses and to improve its dissipation has been presented in the paper.

The Microstructure and Mechanical Properties of the Low Carbon Microalloy Steel by High Voltage Electropulse Heating

The low carbon microalloy steel samples were heated to different temperatures by high voltage electropulse discharge heating method. The temperature of sample increases with the discharge current density. Microstructures were observed by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show that coexist microstructure of ultrafine ferrite grain and martensite can be obtained by proper high voltage electropulse discharge heating process parameter. The tensile testing indicate that better mechanical properties were obtained, including 758MPa yield strength, 796MPa ultimate strength and 12% total elongation.

Microstructure evolution and thermal expansion of Cu-Zn alloy after high pressure heat treatment

The thermal expansion coefficients of Cu-Zn alloy before and after high pressure treatment were measured by thermal expansion instrument in the temperature range of 25？700 ℃,and the microstructure and phase transformation of the alloy were examined by optical microscope,X-ray diffractometer（XRD） and differential scanning calorimeter（DSC）.Based on the experimental results,the effects of high pressure treatment on the microstructure and thermal expansion of Cu-Zn alloy were investigated.The results show that the high pressure treatment can refine the grain and increase the thermal expansion coefficient of the Cu-Zn alloy,resulting in that the thermal expansion coefficient exhibits a high peak value on the α-T curve,and the peak value decreases with increasing the pressure.

Evaluation of ultra-fine grained tungsten under transient high heat flux by high-intensity pulsed ion beam

Pure tungsten, oxide dispersion strengthened tungsten and carbide dispersion strengthened tungsten were fabricated by high-energy ball milling and spark plasma sintering process. In order to evaluate the properties of the tungsten alloys under transient high heat flues, four tungsten samples with different grain sizes were tested by high-intensity pulsed ion beam with a heat flux as high as 160 MW/（m^2·s^-1/2）. Compared with the commercial tungsten, the surface modification of the oxide dispersion strengthened tungsten by high-intensity pulsed ion beam is completely different. The oxide dispersion strengthened tungsten shows inferior thermal shock response due to the low melting point second phase of Ti and Y2O3, which results in the surface melting, boiling bubbles and cracking. While the carbide dispersion strengthened tungsten shows better thermal shock response than the commercial tungsten.