Papers by Keyword: Magnetic Field

Abstract: This study investigated the combined influence of stochastic surface roughness patterns and a magnetic field produced by an infinitely long wire on the distribution of hydrodynamic pressure in journal bearings lubricated with ferrofluids. According to our results, the magnetic field can raise the dimensionless pressure, improve the dimensionless load capacity and reduce the modified friction coefficient, especially at high eccentricity ratio. However, these bearing Characteristics are also influenced by surface roughness pattern depend on the length to diameter ratio λ, and the critical value of λ equal to 0.6, 0.95 and 1.8 in this study.

Abstract: Alloy electrodeposition with superimposed uniform magnetic field leads to Lorentz force generation. The Lorentz force is a factor which is able to modify the deposit structure, its texture, morphology and magnetic properties. The objective of the presented research was to show the composition, morphology and the surface roughness development of Fe-Ni binary alloys electrodeposited under the influence of the uniform magnetic field. The applied magnetic field caused increase of the paramagnetic element content in the alloys. The surface roughness decrease with an external magnetic field application was observed.

Abstract: Cu-Ag-Zr alloy is a newly developed copper alloy material with an excellent combination of high mechanical strength and high electrical conductivity. Magnetic field was used in the solidification of Cu-Ag-Zr alloy. The results showed that with the application of magnetic field, formerly coarse columnar grain turned into homogeneous equiaxed grain. After aging, the precipitate of Zr had an increment and became more refined due to the reduction of segregation. The tensile strength and microhardness of Cu-0.1Ag-0.3Zr alloy under magnetic field of 15 mT increased by 17% and 10%, respectively. The electrical conductivity, with a slight decrease, was still as high as 92.4 %IACS.

Abstract: This study examines the relation between the thickness of a specimen and the weight of an impactor for evaluating the shock absorption performance of magneto-rheological (MR) elastomers with and without a magnetic field. The shock absorption performance can be evaluated by calculating impact energy. The MR elastomer is a smart material and its mechanical properties change under the influence of a magnetic field. The drop impact test is performed to evaluate the amount of shock absorption of the MR elastomer for each test condition. Tests are also performed by varying the magnetic field during impact to improve the shock absorption performance of the MR elastomer, which is related to impact load. The results show a better shock absorption performance with a thicker MR elastomer, lighter impactor, and without a magnetic field. Also, the magnitude of impact and the time duration for stabilization are improved when the magnetic field is varied during the test.

Abstract: With the purpose of studying the main influence on the cylinder-typed magneto-rheological fluid (MRF) clutch, the relationship between the output of shear stress and its affecting factors is presented in this paper; through theoretical derivation from the Bingham Model and the cylinder-typed shear model, the stress born by the MRF in the clutch is analysed, and the affecting factors on the clutch is also simulated and verified through experiments. The study shows that as the magnetic field strengthens, the shear stress of the cylinder-typed MRF clutch grows linearly, with proportionality constant at 0.162; the increase of shear rate, relevant to the magnetic field strength, makes little difference to the torque output, with proportionality constant at 0.00026B. The results indicate that mechanical-electrical integration of clutch devices can be achieved through the control of magnetic field output of the electromagnet.

Abstract: The paper studies the processes occurring in low-temperature plasma in the magnetic field. It shows that the laser excitation of molecular oxygen can increase the fraction of singlet pairs formed as a result of collisions between oxygen and carbon molecules. This facilitates the separation of ¹²С and ¹³С isotopes.

Abstract: The atomic lines intensity of carbon and oxygen in low-temperature plasma are shown. Measurements are made at different distances from the electrode depending on the composition of the plasma forming gas mixture and external magnetic field presence.

Abstract: Rotor inter-turn short-circuit is a common fault in generator and it is a research hotspot to identify the fault at its early stage. Considering the disadvantage of circuit analytical method, this paper establishes a 2D transient finite element electromagnetic-circuit coupling model, and calculates the magnetic field at normal and fault situations through the powerful post-processing function of ANSOFT, then magnetic flux density cloud pictures and air-gap magnetic flux density curves of different operating conditions are got. Using MATLAB to analyze and deal with the air-gap flux density cures, we can get the differences of faults in different levels and different positions, which provide a basis for further study of rotor inter-turn short-circuit fault.

Abstract: Steroid microbial conversion system is a complex but controllable system with multiple factors involved. In the process of steroid microbial conversion, strain screening and selection is essential to improving productivity and reducing costs. However, good-quality strains need optimal environmental conditions to best play their roles. Therefore, environmental conditions can significantly affect the conversion rate in addition to the quality of the strains utilized. Microbial environment includes physiological and biochemical environment, physical and materialized environment and hydro-mechanical environment. For example, the composition, pH value and dissolved oxygen of culture medium affect the physiological and biochemical environment; gas-liquid interface and liquid-solid interface of culture media affect the physical and materialized environment; scattered and mixed conditions of culture system affect the hydro-mechanical environment. Representative physical factors and their applications in steroid microbial conversion system are briefly reviewed herein.

Abstract: Power systems as 10kV, 35kV and etc have a lot of high-voltage three-phase three-element combined transformer. At present, all of the combined transformers are verified according to single-phase verification method, but the results can’t reflect the true error characteristics of combined transformer. So, it is suggested to adopt three-phase verification method to verify combined transformer. However, when combined transformer is verified according to three-phase verification method, it has not been clear yet that what influence magnetic field generated by current has on voltage error. In this paper, through voltage error test on combined transformer with three-phase verification method at different current, it is discovered that magnetic field has a larger influence on voltage error in the presence of a magnetic field, with the increase of voltage, the influence of magnetic field on voltage error decreased gradually from larger values. The use of three-phase verification method and appropriate modification of current error limits are recommended when combined transformer is verified.