Applied Mechanics and Materials Vols. 556-562

Abstract: It is photoconductive antenna for terahertz generation and detection to be applied widely as a radiation resource. It has a significant application prospect in many areas such as terahertz imaging, spectrum detection and so on. In this paper, we proposed a 3-D radiation feature calculation method for terahertz photoconductive antenna using Finite Difference Time Domain (FDTD), and elaborated the influence of semiconductor drift current, diffusion current to electromagnetic field based on the radiation principle of photoconductive antenna. According to actual application condition, we simplified drift equation and continuity equation, and obtained the iteration equation of current density, electric field and magnetic field, and at last, we illustrated a calculation flow of radiation properties of photoconductive antenna.

Abstract: Power line interference (PLI) may lead to the signal-to-noise ratio (SNR) decline sharply on biomedical signals, including the electrocardiogram (ECG). The proposed method employs the relationship of frequency and weights in adaptive filter to track the frequency variation of PLI. Real ECG signals from MIT-BIH database was used in the experiment, and they were corrupt by an artificial PLI signal for experiment. Correction performances of the proposed method and traditional adaptive method were compared by SNR in the paper. The results showed that the proposed method is consistently superior to the traditional one when the power line interference is vary with time, and the proposed method can track the variation of power line interference effectively.

Abstract: For the low efficiency in generating candidate item sets of apriori algorithm, this paper presents a method based on property division to improve generating candidate item sets. Comparing the improved apriori algorithm with the other algorithm and the improved algorithm is applied to the power system accident cases in extreme climate. The experiment results show that the improved algorithm significantly improves the time efficiency of generating candidate item sets. And it can find the association rules among time, space, disasters and fault facilities in the power system accident cases in extreme climate. That is very useful in power system fault analysis.

Abstract: High speed analog signals output by test object in the field of testing and controlling is typical. This paper designed a high-speed AD data acquisition system responding to this situation. In the design of the system, data is first conditioned by the analog channel. FPGA is then employed to receive, decelerate, reorganize and store the high-speed LVDS data output by AD. Data is displayed in computer after being collected by ARM from FGPA. Real circuit designing demonstrated that the high-speed data acquisition system of AD based on 100M bandwidth of analog channel is workable.

Abstract: A switching power supply of high performance switches is designed in this thesis, which is able to supply stable power energy to switches. In the paper, I analyze the characteristic of switches load, and analyze the main circuit structure based on the study of basic principle of switches switching power supply. As a key point, I have designed a main circuit which adopts flyback Topological structure, such as, input circuit, rectification filter circuit, output circuit, feedback circuit, ancillary circuit of switches switching power supply and high-frequency transformer. The result of design is able to provide proper power supply for high performance switches.

Abstract: A new joint method is presented to estimate the 2-D DOA and polarization parameters of far-field sources based on four order cumulant. The method adopts L array, and every sensor consists of orthogonal dipole-pairs with the same coordinate axis direction, which measure the x-axis and y-axis electric-field components of the far-field signals. The method constructs four four-order cumulant matrixes by receiving polarized array data and does not require any spectral peak search and parameter pairing, can be applied to additive Gaussian white noise or color noise environment. The performance of the proposed method is verified by computer simulations.

Abstract: Ellipse expression is difficult to be found directly. And the detail form which is important for electrical field analysis has not been described. The arrangement mode of lines affect electrical field significantly. Hence, simulation of triangular and horizon arrangement are proceeded in this paper. The terms include rotation track, rotation direction and initial phase angle.

Abstract: Inverter technology as the key part of using new energy technology, can be very effective to new energy sources such as solar, battery and fuel cell energy conversion of ac electrical energy transform into ac power, and can be connected to the grid. Therefore, the inverter technology has an extremely important statue in modern society.

Abstract: In recent years, as the SVC device have also been used for DC ice melting system, the installment is still on the rise, it is necessary to study the loss situation. This paper firstly analyzed the theory of the loss of its each part of the device, and then finished a simulation based on the PSCAD software. We hope the research can give some value guidance on SVC assembled for the power grid.

Abstract: DC voltage, input voltage and current need testing for control circuit of general PFC circuit that makes circuit complex and high cost. And using of sensors decreases the reliability of circuit. Hence, simulation analysis of single phase APFC without DC voltage sensor is present in this paper.