Papers by Keyword: Electromagnetic Field (EMF)

Abstract: t is generally needed to know precisely spatial distribution of lightning electromagnetic fields in the lightning protection measurements. Therefore, the research on the lightning electromagnetic field is of practical significance. In this paper, the Maxwell equations were used to calculate and analyze the spatial distribution of lightning electromagnetic fields surrounding lightning current. And the expressions of lightning current electromagnetic fields were deduced under the assumption that the earth was under the condition of perfect conductor. The spatial distributions of the components of lightning electromagnetic fields have been plotted by Matlab. The results would provide fundamental theory for the research of lightning electromagnetic field and lightning protection measurements.

Abstract: Nowadays, since there are many artificial intelligence techniques introduced into our daily life, which brings us much convenience, its a real hope that our transportation can be improved by artificial intelligence. In this article, a smart car with the detecting and following ability is introduced. The whole system is composed of the road track signal device; the electromagnetic sensor; the power source manage device; the engine drive device and the parking position detecting device. By using the PID, Bang-Bang and fuzz control methods, the smart car can collect the signal automatically and control the car moving effectively. When there are specially designed roads with electromagnetic field, our smart cars can automatically drive themselves.

Abstract: In paper problem concerning inoculation of primary structure of Al with purity of 99,5% and 99,8% and AlSi2 alloy, which is realized mainly by intensification of liquid metal movement in mould is presented. In aim of realization of forced movement during the crystallization of liquid metal was used horizontal electromagnetic field produced by the induction coil (stirrer) supplied by current with elevated frequency. The degree of structure refinement was represented mainly by equiaxed crystals zone content on transverse section of ingot and average area of macro-grain in this zone. Effect of structure refinement obtained by influence of electromagnetic stirring was compared with refinement obtained by use of traditional inoculation, which consists in introducing of additives i.e. titanium, boron and strontium to metal bath. The results of studies and their analysis show possibility of effective refinement of pure Al and Al-Si alloy primary structure, only with use of horizontal electromagnetic field and without necessity of application of inoculants such a Ti and B. This method of inoculation is important, because inoculants decrease the degree of purity and electrical conductivity of pure Al. Moreover inoculants are reason of point cracks formation during rolling of ingots.

Abstract: Microwave power standard adopts calorimetry techniques to calibrate the effective efficiency of the thermistor mount. Correction factor is the key of calibration thermistor mount.The microwave power standard mainly adopted short-circuited mode to determine the correction factor so far, but it must consider the effects of microwave power absorbed by short plate to thermopile, so the method that how to get the power dissipated in the short plate is the key to calculating correction factor and its uncertainty. This paper presents a new method based on electromagnetic field theory to consider the short-circuit dissipation power. A detailed analysis of its superiority over the traditional method is shown. It reduces the uncertainty of the correction factor reasonably, in other words, reduces the uncertainty of the microwave power standard.

Abstract: Besides the already familiar mobile telephony macro base stations visible in our cities, there are also pico base stations inside many office buildings. This paper investigates the exposure to Electro Magnetic Fields (EMFs) produced by this equipment, in order to verify that the ICNIRP general public reference levels are met.

Abstract: Based on the interfacial reaction model between Ti and ZrO₂ in gravity field, taking account of the effect of electromagnetic field, a comprehensive numerical model for simulation of heat and mass transfer is established to study the interfacial reaction between liquid Ti and ZrO₂ in electromagnetic field. With the proposed model, numerical simulations are preformed to investigate the influences of pouring temperature, holding time on the oxygen concentration and reactive layer thickness in metal. The results show that both the oxygen concentration and the thickness of reactive layer in metal increase with increasing the holding time and the pouring temperature. The thickness of reactive layer in electromagnetic field is greater than that in gravity field.

Abstract: This paper presents three important electromagnetic parameters design principles in modeling a large canned motor such as the canned motor inside the nuclear reactor coolant pump. The performances of the canned motor within the nuclear reactor coolant pump are also analyzed by establishing the two-dimensional transient electromagnetic field model. The simulation result of magnetic flux density distribution of canned motor is very close to practical situation. Simultaneously the efficiency, power factor and break-down torque of canned motor are analyzed through two-dimensional electromagnetic field finite element method.

Abstract: In paper problem concerning inoculation of primary structure of aluminum with purity of 99,5% and 99,8%, which is realized mainly by intensification of liquid metal movement in mould is presented. In aim of realization of forced movement during the crystallization of liquid metal was used rotating electromagnetic field produced by the induction coil supplied by current with elevated frequency. The degree of structure refinement was represented by equiaxed crystals zone content on transverse section of ingot and average area of macro-grain in this zone. Effect of structure refinement obtained by influence of electromagnetic field was compared with refinement obtained by use of traditional inoculation, which consists in introducing of additives i.e. titanium, boron and carbon to metal bath. The results of studies and their analysis show possibility of effective refinement of pure Al primary structure, only with use of rotating electromagnetic field and without necessity of application of inoculants such a Ti, B and C. This method of inoculation is important, because inoculants decrease the degree of purity and electrical conductivity of pure Al. Moreover Ti and B are reason of point cracks formation during rolling of ingots.

Abstract: This paper has designed and produced an ac/dc permanent magnet synchronous generator which used in ac/dc power system independent. The design of the motor and the basic properties of the motor is discussed in this paper. In order to reduce the voltage regulation of the permanent magnet generator, installation of a soft magnetic material in the generator permanent magnetic pole tail, by increasing the motor load quadrature axis reactance drop improves motor voltage regulation. A prototype is made and test analysis, the generator voltage regulation rate of small, high efficiency, and the simulation result is consistent with the basic design to achieve the requirements.

Abstract: Recent laboratory experiments demonstrate that electrical conductivity of upper mantle (UM) minerals is greatly increased by small amounts of water or by partial melt. Determination of deep conductivity using electromagnetic (EM) methods can thus provide constraints on the presence of volatiles and melting processes in UM. Probing conductivity at UM depths requires EM data with periods of a few to one cycle per day. This is a challenging period range for EM studies due to the spatially complex ionospheric source that dominates at these periods. The idea of exploiting tidal signals for EM studies of the Earth is not new, but so far it was used only for interpretation of inland and transoceanic electric field data due to M2. Emphasis in this work is made on a discussion of sea bottom magnetic field of the same origin.