H. M. Srivastava, J. A. Tenreiro Machado and Xiao-Jun Yang
Wenyu Hu, Zhao Wang, Xiaosong Yang and Jian J. Zhang
Xiao-Jun Yang, Dumitru Baleanu and J. A. Tenreiro Machado
S. Yang and J.-Gon. Kim
In future, more mobile devices with different frequencies will be used at the same time. Therefore, it is expected that the trouble caused by wave interference between devices will be further intensified. In order to prevent this trouble, investigation of selective frequency transmission or absorption material is required. In this paper, magnetic properties of nickel-zinc-copper ferrite nano powder was researched as wave absorber. (Nia-Znb)xCu1-xFe2O4(NZCF) nanoparticles were fabricated by the sol-gel method. The influence of copper substitution on lattice parameter change was analyzed by X-ray diffraction (XRD), particle size was analyzed by scanning electron microscopy (SEM), and Magnetic properties analyzed by vibrating sample magnetometer (VSM). The NZCF and Nickel-zinc ferrite (NZF) lattice parameter difference was 0.028 Å and particle size was calculated as 30 nm with the XRD peak. The VSM results of (Ni0.3-Zn0.3)0.6Cu1-0.6Fe2O4 annealed sample at 700°C for 3hous were 58.5 emu/g (Ms), 22.8 Oe (Hc). It was the most suitable magnetic properties for wave absorber in this investigation.
J. Yang, M. Dou and D. Zhao
Due to the star connection of the windings, the impact of the third harmonic which does not exist in three-phase permanent magnet synchronous motor (PMSM) cannot be ignored in five-phase PMSM. So the conventional sensorless control methods for three-phase PMSM cannot be applied for five-phase PMSM directly. To achieve the sensorless control for five-phase PMSM, an iterative sliding mode observer (ISMO) is proposed with the consideration of the third harmonic impact. First, a sliding mode observer (SMO) is designed based on the fivephase PMSM model with the third harmonic to reduce the chattering and obtain the equivalent signal of the back electromotive force (EMF). Then, an adaptive back EMF observer is built to estimate the motor speed and rotor position, which eliminates the low-pass filter and phase compensation module and improves the estimation accuracy. Meanwhile, by iteratively using the SMO in one current sampling period to adjust the sliding mode gains, the sliding mode chattering and estimation errors of motor speed and rotor position are further reduced. Besides, the stability of the SMO and the adaptive back EMF observer are demonstrated in detail by Lyapunov stability criteria. Experiment results verify the effectiveness of the proposed observer for sensorless control of five-phase PMSM.
X Chen, J Guo, J Huang, J Yang, T Jiang, D Sun and X Yu
Experiments were conducted from 1996 to 1998 at the Hefei Institute of Economics and Technology and at the Oriental Experimental Station of the Zhejiang Province (China). Seven F1 hybrids and three parental varieties of Oriental tobaccos were evaluated for the characteristics of photosynthetic and transpiration rates, esterase isozymes, resistance to black shank, quality and product potential from the 1996-1998 growing seasons. Tobacco leaves had higher photosynthetic rates and many differences among genotypes in the early stage of plant vigorous growth compared with more mature leaves. However, transpiration rates were lower in the younger leaves and greater in the more mature leaves. All the entries had four common bands (B1, B3, B4 and B6) of the esterase isoenzymes. Differences between entries resulted from in having or not having the B2 and B5 bands and color intensity differences of all the bands. These differences could be used to identify individual entries. The F1hybrids Samsun X Toy and Samsun X Argjiro, compared with the CK Samsun control, had obvious heterotic vigor in the characteristics of product, for yield, quality and resistance to black shank. The F1 hybrid Samsun X Toy maintained higher photosynthetic and transpiration rates in the two growth stages compared to other entries. However, the F1hybrid Samsun X Argjiro had higher photosynthetic rates and lower transpiration rates in the early growth stage and the two rates were lower in the later stage, but it maintained higher photosynthetic rates for the whole growth stage. Net photosynthetic rates had a significant positive correlation with yield product, quality and resistance to black shank of the Oriental tobacco F1hybrids.
H Yang, J Liu, K Li, X Yin, X Tan and J Wang
3-Oxo-α-ionol ethyl carbonate, a precursor of megastigmatrienones was prepared by reduction of α-ionone to α-ionol, followed by esterification with ethyl chloroformate and then by oxidation with t-butyl chromate. The total yield was about 23%. Infrared (IR) and mass spectra of this compound were determined. Upon smoking, cigarettes to which 0.002% by weight of the titled compound was added had an improved and more harmonious flavor. The smoke was sweeter and had a cleaner after taste. Experimental results suggest that the title compound added to the tobacco pyrolyzes to form megastigmatrienones during smoking.
H. Rudianto, G.J. Jang, S.S. Yang, Y.J. Kim and I. Dlouhy
Premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder was analyzed as matrix in this research. Gas atomized powder Al-9Si with 20% volume fraction of SiC particles was used as reinforcement and added into the alloy with varied concentration. Mix powders were compacted by dual action press with compaction pressure of 700 MPa. High volume fraction of SiC particles gave lower green density due to resistance of SiC particles to plastic deformation during compaction process and resulted voids between particles and this might reduce sinterability of this mix powder. Sintering was carried out under ultra high purity nitrogen gas from 565°-580°C for 1 hour. High content of premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder gave better sintering density and reached up to 98% relative. Void between particles, oxide layer on aluminum powder and lower wettability between matrix and reinforcement particles lead to uncompleted liquid phase sintering, and resulted on lower sintering density and mechanical properties on powder with high content of SiC particles. Mix powder with wt90% of Alumix 431D and wt10% of Al-9Si-vf20SiC powder gave higher tensile strength compare to another mix powder for 270 MPa. From chemical compositions, sintering precipitates might form after sintering such as MgZn2, CuAl2 and Mg2Si. X-ray diffraction, DSC-TGA, and SEM were used to characterize these materials.
H.S. Yang, D.H. Jang and K.J. Lee
FeCrAl is comprised essentially of Fe, Cr, Al and generally considered as metallic substrates for catalyst support because of its advantage in the high-temperature corrosion resistance, high mechanical strength, and ductility. Oxidation film and its adhesion on FeCrAl surface with aluminum are important for catalyst life. Therefore various appropriate surface treatments such as thermal oxidation, Sol, PVD, CVD has studied. In this research, PEO (plasma electrolytic oxidation) process was applied to form the aluminum oxide on FeCrAl surface, and the formed oxide particle according to process conditions such as electric energy and oxidation time were investigated. Microstructure and aluminum oxide particle on FeCrAl surface after PEO process was observed by FE-SEM and EDS with element mapping analysis. The study presents possibility of aluminum oxide formation by electro-chemical coating process without any pretreatment of FeCrAl.
S. Yang, K.-Pil. Jeong, S.-Y. Park and J.-Gon. Kim
Due to the rapid development of the information communication industries, it is expected that next-generation mobile communication devices in the data communication environment will be used at the same time in the L~X band (1–12 GHz). To mutual electric wave interference prevention, research on wave absorbers in L~X band is needed. In this paper, barium ferrite was researched as L~X band wave absorber. The Barium ferrite (BaM, Ba ferrite) substituted by divalent ions (Co2+, Cu2+, Ni2+, Zn2+) and tetravalent ion (Ti4+). The substituted Ba ferrite nanoparticles were fabricated by sol-gel process. Lattice parameter, particle size, magnetic properties, and reflection loss were analyzed by X-ray diffraction (X-RD), a Vibrating Sample Magnetometer (VSM), and a Network Analyzer. Lattice parameter of Ba ferrite was changed 0.0005 to 0.0078 Å in a-b direction, and 0.0187 to 0.0445 Å in c-direction by substituted elements, and it influenced on magnetic anisotropy. In addition, Co-Ti substitution elements influenced that coercive force decrease 5,739 to 2,240 Oe. Moreover, reflection loss frequencies were shifted from 16.3 GHz to 14.4 and 17.4 GHz by substituted elements Co-Ti and Zn-Ti.