In this paper, the toroidal field B of a tokamak produced by separate coils has been calculated from the basic electrodynamic theory. As an example, the toroidal magnetic field B(R) in TEXT-U tokamak is plotted, and t...In this paper, the toroidal field B of a tokamak produced by separate coils has been calculated from the basic electrodynamic theory. As an example, the toroidal magnetic field B(R) in TEXT-U tokamak is plotted, and the curve is fitted well to the analysis formula B(R) = BoRo/R with a precision of several percents.展开更多
This paper analyzes the sources of heat losses in magnetic fluid bearings,proposes various cou-pling relationships of physical fields,divides the coupled heat transfer surfaces while ensuring the continuity of heat fl...This paper analyzes the sources of heat losses in magnetic fluid bearings,proposes various cou-pling relationships of physical fields,divides the coupled heat transfer surfaces while ensuring the continuity of heat flux density,and analyzes the overall heat dissipation pathways of the bearings.By changing parameters such as input current,rotor speed,and inlet oil flow rate,the study applies a multi-physics field coupling method to investigate the influence of different parameters on the temper-ature field and heat dissipation patterns of the bearings,which is then validated through experi-ments.This research provides a theoretical basis for the optimal design of magnetic fluid bearing sys-tems.展开更多
Field computation, an emerging computation technique, has inspired passion of intelligence science research. A novel field computation model based on the magnetic field theory is constructed. The proposed magnetic fie...Field computation, an emerging computation technique, has inspired passion of intelligence science research. A novel field computation model based on the magnetic field theory is constructed. The proposed magnetic field computation （MFC） model consists of a field simulator, a non-derivative optimization algo- rithm and an auxiliary data processing unit. The mathematical model is deduced and proved that the MFC model is equivalent to a quadratic discriminant function. Furthermore, the finite element prototype is derived, and the simulator is developed, combining with particle swarm optimizer for the field configuration. Two benchmark classification experiments are studied in the numerical experiment, and one notable advantage is demonstrated that less training samples are required and a better generalization can be achieved.展开更多
Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields we...Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields were generated from a circular array of solenoids and presented with accelerating or decelerating rotation velocities. The range of photon radiant flux density was in the order of 10-12 W·m-2. Microtubules preparations that had been exposed for only 2 min to a magnetic field configuration corresponding to the electric field pattern that induced long-term potentiation in neural tissue when applied as electric current displayed peaks of spectral power densities within 7 - 8 Hz, 9.5 Hz, 14 - 15 Hz, and 22 Hz bands. The major peak (9.4 Hz) bandwidth was approximately 0.1 Hz. While microtubule preparations exposed for 2 min to a 7 Hz sine-wave or in the absence of a field emitted an overall similar level of spectral power density, the peaks in power density were not present. Treatment with the LTP patterned fields, compared to the baseline or sine-wave fields primarily altered the frequency band in which the amplitude of the photon field was expressed. These results suggest that the photon emissions from microtubule preparations have the capacity to respond to specifically-patterned or geometric shapes of magnetic fields by altering spectral configurations rather than the absolute numbers of photons.展开更多
A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid （Pb）/ liquid （Sn） diffusion couples were investigated under various static magnetic fields. Results show that the...A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid （Pb）/ liquid （Sn） diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field （〈0.3 T）. When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level （0.8-5 T）, the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.展开更多
In this study,the evaporation characteristics and drying patterns of various sessile ferrofluid droplets on certain substrate under horizontal magnetic fields of controlled intensities are reported.The effects of drop...In this study,the evaporation characteristics and drying patterns of various sessile ferrofluid droplets on certain substrate under horizontal magnetic fields of controlled intensities are reported.The effects of droplet concentration and magnetic field intensity on the duration of each evaporation stage and drying patterns of droplets have been systematically investigated.It turned out that a plateau appears at the initial stage of evaporation in the absence of magnetic field and it was found that the plateau value is positively correlated with the concentration of ferrofluid droplets.Under the external magnetic field,the evaporation time of droplets decreases,the stage of contact line retreat extends,the stage of late pinning mode shortens,and the deposition area of ferrofluid droplet decreases compared to that of without magnetics field.The deposition area increases gradually and becomes more uniform with the increase of magnetic field.The decrease of friction force which is due to the decrease of the number of nanoparticles at the contact line under external magnetic field is the main reason for the observed phenomena.We found that the coffee ring and the uniform deposition inside the droplet will be destroyed when the magnetic field intensity is higher than a critical value.Our work has a significant reference value for the evaporation of sessile magnetic fluid droplets under the applied magnetic field,especially when the drying pattern needs to be precisely controlled,such as in spray or biomedicine.展开更多
文摘In this paper, the toroidal field B of a tokamak produced by separate coils has been calculated from the basic electrodynamic theory. As an example, the toroidal magnetic field B(R) in TEXT-U tokamak is plotted, and the curve is fitted well to the analysis formula B(R) = BoRo/R with a precision of several percents.
基金the National Natural Science Foundation of China(No.52075468)the Natural Science Foundation of Hebei Province(No.E2020203052)+1 种基金the Key Scientific Research Projects of North China University of Technology(No.ZD-YG-202306-23)the Tangshan Science and Technology Project(No.23130201E).
文摘This paper analyzes the sources of heat losses in magnetic fluid bearings,proposes various cou-pling relationships of physical fields,divides the coupled heat transfer surfaces while ensuring the continuity of heat flux density,and analyzes the overall heat dissipation pathways of the bearings.By changing parameters such as input current,rotor speed,and inlet oil flow rate,the study applies a multi-physics field coupling method to investigate the influence of different parameters on the temper-ature field and heat dissipation patterns of the bearings,which is then validated through experi-ments.This research provides a theoretical basis for the optimal design of magnetic fluid bearing sys-tems.
基金supported by the National Natural Science Foundation of China(60903005)the National Basic Research Program of China(973 Program)(2012CB821206)
文摘Field computation, an emerging computation technique, has inspired passion of intelligence science research. A novel field computation model based on the magnetic field theory is constructed. The proposed magnetic field computation （MFC） model consists of a field simulator, a non-derivative optimization algo- rithm and an auxiliary data processing unit. The mathematical model is deduced and proved that the MFC model is equivalent to a quadratic discriminant function. Furthermore, the finite element prototype is derived, and the simulator is developed, combining with particle swarm optimizer for the field configuration. Two benchmark classification experiments are studied in the numerical experiment, and one notable advantage is demonstrated that less training samples are required and a better generalization can be achieved.
文摘Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields were generated from a circular array of solenoids and presented with accelerating or decelerating rotation velocities. The range of photon radiant flux density was in the order of 10-12 W·m-2. Microtubules preparations that had been exposed for only 2 min to a magnetic field configuration corresponding to the electric field pattern that induced long-term potentiation in neural tissue when applied as electric current displayed peaks of spectral power densities within 7 - 8 Hz, 9.5 Hz, 14 - 15 Hz, and 22 Hz bands. The major peak (9.4 Hz) bandwidth was approximately 0.1 Hz. While microtubule preparations exposed for 2 min to a 7 Hz sine-wave or in the absence of a field emitted an overall similar level of spectral power density, the peaks in power density were not present. Treatment with the LTP patterned fields, compared to the baseline or sine-wave fields primarily altered the frequency band in which the amplitude of the photon field was expressed. These results suggest that the photon emissions from microtubule preparations have the capacity to respond to specifically-patterned or geometric shapes of magnetic fields by altering spectral configurations rather than the absolute numbers of photons.
基金financially supported by the National Natural Science Foundation of China (Nos. 51201029, 51071042 and 51374067)the Fundamental Research Funds for the Central Universities (Nos. N130409002, N130209001 and N130709001)+1 种基金the China Postdoctoral Science Foundation (No. 2012M520637)the National Basic Research Program of China (No. 2012CB619506)
文摘A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid （Pb）/ liquid （Sn） diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field （〈0.3 T）. When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level （0.8-5 T）, the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.
基金The authors gratefully acknowledge the financial support of the National Natural Science Foundation of China(Grants No.52025061 and 51961130386)Royal Society-Newton Advanced Fellowship(Grant No.NAF/R1/191163)This work was also supported by the China Fundamental Research Funds for the Central Universities.
文摘In this study,the evaporation characteristics and drying patterns of various sessile ferrofluid droplets on certain substrate under horizontal magnetic fields of controlled intensities are reported.The effects of droplet concentration and magnetic field intensity on the duration of each evaporation stage and drying patterns of droplets have been systematically investigated.It turned out that a plateau appears at the initial stage of evaporation in the absence of magnetic field and it was found that the plateau value is positively correlated with the concentration of ferrofluid droplets.Under the external magnetic field,the evaporation time of droplets decreases,the stage of contact line retreat extends,the stage of late pinning mode shortens,and the deposition area of ferrofluid droplet decreases compared to that of without magnetics field.The deposition area increases gradually and becomes more uniform with the increase of magnetic field.The decrease of friction force which is due to the decrease of the number of nanoparticles at the contact line under external magnetic field is the main reason for the observed phenomena.We found that the coffee ring and the uniform deposition inside the droplet will be destroyed when the magnetic field intensity is higher than a critical value.Our work has a significant reference value for the evaporation of sessile magnetic fluid droplets under the applied magnetic field,especially when the drying pattern needs to be precisely controlled,such as in spray or biomedicine.
