Advanced Materials Research Vols. 926-930

Abstract: According to previous studies on electrostatic filament deflectors (EFD), the uniformity of spunbond materials can be significantly improved using EFD. In this study, the electric field of EFD was stimulated using Comsol Multiphysics. It was found that appropriate needle-needle distance, and short distances between filaments and needles were beneficial to the uniformity of spunbond. It was also demonstrated that EFD can improve uniformity of spunbond significantly.

Abstract: As a result of using converter and the other power electronic devices on the side of doubly-fed induction generator (DFIG) rotor, it will produce a large amount of harmonic current at runtime. In order to reduce the harmonic pollution to power network, DFIG uses a variety of harmonic suppression measures. This paper introduces the working principle of DFIG and the harmonic suppression, at the same time, the effect of harmonic suppression through the Matlab simulation is analyzed.

Abstract: Passive filter design usually aim to limit harmonic voltage in reasonable level in power system, and choose minimal capacitor volume for the sake of cost. However, the effect of inductance in transformer is not considered in general principles from relevant references. The paper takes the inductance into consideration on designing parameters of Passive filter, improved the general method. The simulation results prove that the filter designed by improved method operates more outstanding than the general method.

Abstract: Hydroxayapatite coating was prepared on titanium (Ti) substrate by pulsed electrochemical method. Fourier Transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to investigate the microstructure of the coatings. The results showed that Hydroxyapatite coating was successful prepared on titanium substrate by pulsed electrochemical method.

Abstract: Magnetic resonance wireless power transmission technology is based on the phenomenon of resonant coupling to realize non-contact power transmission via near magnetic field. Based on the mutual coupling model of resonance system, the influence laws of system transmission parameters, such as coil coupling coefficients, load resistance, etc., on the transmission performance are theoretically studied in this paper. The research results shows that the power high-efficiency and high-quality transmission does not depend on the large coil loop coupling coefficient and the working frequencies of maximum power and maximum efficiency transmission do not coincide at most condition. Transmission systems with a high resonance frequency can produce high power and efficiency transmission over short distances. In addition, by increasing the coil diameter or wire diameter can improve the system quality factor, and optimize the energy transmission performance.

Abstract: Using the full-potential linerized augumented plane-wave method based on the density function theory, we theoretically predict the Heusler compound Lu₂FePb is a new three-dimensional topological insulator system. We also point out that the spin-orbit coupling is not the leading cause but an account can add further fuel to the band inversion.

Abstract: Geometric structure and electronic structure of wurtzite ZnO have been calculated adopting first principle plane wave ultrosoft pseudo potential method based on density functional theory, and band structure, electronic state density, differential charge distribution of ZnO have been subjected to systematic analysis, the results of which show that ZnO is a type of wide gap and direct gap semiconductor, with conduction band bottom and valence band top at the point Γ of Brillouin zone and valence band top showing obvious triply degenerateΓ7、Γ9、Γ7,while conduction band bottom beingΓ7. electronic structure calculation shows that Zn 3d narrow orbit between-6 and-4 eV has been fully filled with electrons and that O 2p wide orbit between-4 and 0 eV has also been fully filled with electron. In addition, charge density calculation shows that ZnO is metal oxide semiconductor with hybrid bond characterized by high ionicity and low covalent bond, accordingly, the above mentioned findings are superior to value of calculation mentioned in some documents.

Abstract: This paper used STM32F103VET6 as the core processor, SD card to store the image file. In addition, the host controller read, write, operate and decode the image data stored in the SD card with the SPI communication mode. Then it will send the processed data to the indication controller. And finally display the photos with TFT-LCD. The function keys send interruption requests to the processor by external interrupting. With different interrupt handler, the processor can show and switch images in the digital photo frame in different ways so as to realize the various functions of the digital photo frame.

Abstract: In order to improve the detection distance of laser proximity fuze without increasing laser power, the capability of laser fuze receiving weak laser echo signal must be improved. An avalanche photodiode (APD), which had the advantages of high sensitivity, low noise, with inner gain, was used as photodetector in laser fuze system to improve the capability of laser fuze detecting weak signal. The equivalent noise model of APD photoelectric conversion was analyzed, and the low-noise preamplifier and voltage amplification circuit matching the avalanche photodiode were designed. The noise ratio and frequency bandwidth of amplification circuit were analyzed and calculated, also the simulation and experimental verification were accomplished. The results showed that the circuit has wide bandwidth and high signal to noise ratio,which meets the requirements of subsequent processing circuitry of laser fuze.

Abstract: This paper deals with a detailed study of ESD failure mode and how to strengthen of the VDMOS used for power applications. The ESD post-zapped failure of power VDMOS transistors due to HBM, MM, and CDM stresses are examined in this work. Through standard failure analysis techniques by using EMMI and SEM were applied to identify the failure locations. The MM failure mode in this power MOSFET was caused by the gate oxide breakdown near n⁺ region in the source end as an ESD zapping. And, the ESD failure damage under HBM and CDM stresses were caused by the gate material molten near the gate pad and tunneled through the oxide layer into silicon epitaxial layer. Furthermore, the ESD robustness designs of power VDMOS transistors are also addressed in this work. The first ESD incorporated design is Zener diodes back-to-back clamping the gate-to-source pad, and on the other hand, another one excellent design contains two Zener diodes clamping the gate-to-source and gate-to-drain terminals of a VDMOS, respectively.