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71.
针对三相整流负载产生的6k±1次谐波,提出静止坐标系下的改进型6k±1重复控制策略。同时将比例控制与改进型重复控制相结合,设计改进重复控制并联比例的复合控制结构。为减小改进重复控制中延时环节不为整数的影响,采用基于Lagrange插值近似的FIR滤波器逼近分数延时特性。最后对系统进行稳定性分析和详细设计方法进行推导。通过Matlab仿真验证改进重复控制策略能有效跟踪6k±1次谐波且具有良好的补偿效果,动态响应较快。 相似文献
72.
73.
Fan Zhang Chuan Zhang Duchao Lv Jun Zhu Weisheng Cao Shuanglin Chen Rainer Schmid-Fetzer 《Journal of Phase Equilibria and Diffusion》2018,39(5):562-570
In this work, high throughput calculation (HTC) is used to identify composition regions with good glass forming ability (GFA) in the Al-Cu-Zr, Cu-Ni-Zr, Cu-Ti-Zr, Cu-Ni-Ti-Zr, Al-Cu-Ni-Ti-Zr, Mg-Ca-Cu, and Mg-Ca-Ni systems. The predicted composition regions agree well with those observed by experiments in the ternary systems, while less satisfactory agreement is found in the Cu-Ni-Ti-Zr quaternary and the Al-Cu-Ni-Ti-Zr quinary systems. The possible causes that lead to the deviation in the higher order systems are discussed. The major advantage of the HTC method used in this study is that it is simple and can be easily applied to multicomponent systems. The color maps of liquidus temperature and solidification range obtained by HTC provide a valuable guidance to the experimentalists, thus they can focus on the composition regions with high potential of forming bulk metallic glasses, avoid unnecessary trial-and-error test and save time and cost. This approach can also be combined with other criteria to filter compositions with better GFA. 相似文献
74.
Jiaojiao Gao Jinpeng Song Ming Lv Lei Cao Juncai Xie 《Ceramics International》2018,44(15):17895-17904
TiC0.7N0.3-HfC cermet tool materials were fabricated by hot-press sintering. Effects of different metal additives (Ni, Co, Ni-Co and Ni-Mo), sintering temperature and holding time on the microstructures and mechanical properties of TiC0.7N0.3-HfC cermets were investigated. Results showed that Ni-Mo or Ni-Co as metal additives was better for the mechanical properties of TiC0.7N0.3-HfC cermets than only Ni or only Co as the metal additives and Ni-Mo better than Ni-Co. HfC particle dispersion existed in these four cermets and only in the TiC0.7N0.3-HfC-Ni-Mo cermet the core-rim structure obviously existed. TiC0.7N0.3-HfC-Ni-Mo cermet had significantly smaller grains than the other three cermets because Ni-Mo can significantly refine the grain. With the sintering temperature increasing from 1450?°C to 1650?°C, grains grew gradually; Vickers hardness and flexural strength decreased gradually and the fracture toughness increased firstly and then decreased. With the holding time increasing from 15?min to 60?min, grains grew gradually; Vickers hardness, flexural strength and the fracture toughness increased firstly and then decreased. TiC0.7N0.3-HfC-Ni-Mo cermets sintered at 1450?°C with 30?min holding time had the better comprehensive mechanical properties with flexural strength of 1346.41?±?31?MPa, fracture toughness of 8.46?±?0.23?MPa?m1/2 and Vickers hardness of 22.91?±?0.22?GPa. 相似文献
75.
Yong Chen Can-Can Zhang Lu Qin Chao-Bin Jiang Kang-Hui Liu Chao Ma Zhen-Tao Wu Rui-Kun Pan Wan-Qiang Cao Cong Ye Zhang Li 《Ceramics International》2018,44(15):18264-18270
The bismuth layer-structured Na0.5Bi4.5-xPrxTi4O15 (x?=?0, 0.1, 0.2, 0.3, 0.4, and 0.5) (NBT-xPr3+) ceramics were fabricated using the traditional solid reaction process. The effect of different Pr3+ contents on dielectric, ferroelectric and piezoelectric properties of Na0.5Bi4.5Ti4O15 ceramics were investigated. The grain size of Pr3+-doping ceramics was found to be smaller than that of pure one, the maximum dielectric constant and Curie temperature Tc gradually decreased with increasing Pr3+ contents, and the dielectric loss decreased at high temperature by Pr3+-doping. Moreover, the activation energy (Ea), resistivity (Z’), remanent polarization (2Pr) and piezoelectric constant (d33) increased by Pr3+-doping. The NBT-xPr3+ ceramics with x?=?0.3 achieved the optimal properties with the maximum dielectric constant of 1109.18, minimum loss of 0.00822 (250?kHz), Ea of 1.122?eV, Z’ of 7.9?kΩ?cm (725 ºC), d33 of 18 pC/N, 2Pr of 12.04 μC/cm2. The enhancement was due to the addition of Pr3+ which suppressed the decreasing of resistivity at high temperature and made it possible for NBT-xPr3+ ceramics to be poled in perpendicular direction, implying that it is a great improvement for Na0.5Bi4.5Ti4O15 ceramics in electrical properties. 相似文献
76.
Pengcheng Zhao Yu Xiang Yan Xu Yuehua Wen Wenfeng Zhang Xiayu Zhu Meng Li Zhaoqing Jin Hai Ming Gaoping Cao 《Ceramics International》2018,44(8):9105-9111
Garnet-type Li5La3Ta2O12 (LLTaO) solid electrolyte is a potential candidate component for future all-solid-state batteries due to its extraordinary stability against the reaction with molten lithium. In contrast with traditional cold isostatic pressing (CIP) method, which generally pursues ultra-high pressure, this paper tries to enhance the density and ionic conductivity of LLTaO by self-consolidation strategy without the assistance of any pressing operations. A LLTaO bulk with a relative density of 95% is obtained. SEM images reveal that the bulk sample is assembled by large dense particles in size of tens of microns indicating that the interstitial space among the particles has been dramatically minimized. Accordingly, the total ionic conductivity and the bulk ionic conductivity at 30?°C are promoted up about one order of magnitude higher to 2.63?× 10?5 S?cm?1 and 1.41?×?10?4 S?cm?1, respectively. Moreover, the lithium ionic migration network in the crystalline unit cell of LLTaO is first explored from its assembled way. A hexagon-like basic unit with tetrahedral Li1 joint sites and Li1- - Li1 edges is identified. The tetrahedral Li1 sites act as crucial junctions for the transportation of lithium ions. This work would significantly stimulate the development of LLTaO electrolyte membrane technology. 相似文献
77.
Zhentao Wang Yanwei Zeng Chuanming Li Zhupeng Ye Liangliang Cao Yuan Zhang 《Ceramics International》2018,44(9):10328-10334
Gd3+ and Fe3+ co-doped cerium oxide electrolytes, Ce0.9Gd0.1‐xFexO2-δ (x?=?0.00, 0.01, 0.03, 0.05, 0.07, 0.10), were prepared by co-precipitation for ultrafine precursor powders and sintering for densified ceramic pellets. The crystal and microscopic structures were characterized by XRD, FESEM and Raman spectroscopy and their electrical properties were studied by AC impedance spectroscopy and the measurement of single cell's outputs. In comparison with Ce0.9Gd0.1O1.95, the ceramic pellets of Ce0.9Gd0.1‐xFexO2-δ with a relative density of 95% can be obtained after sintered at 1000?°C for 5?h, showing a remarkably enhanced sintering performance with a sintering temperature reduction of 500?°C, which might be ascribed to the highly activated migration of constituent species in the cerium oxide lattice doped with Gd3+ and Fe3+ions. Moreover, the electrical conductivity of Ce0.9Gd0.1‐xFexO2-δ can be significantly enhanced depending on the mole fraction x, with Ce0.9Gd0.07Fe0.03O1.95 exhibiting the highest electrical conductivity of 38 mS/cm at 800?°C, about 36% higher than that of Ce0.9Gd0.1O1.95 electrolyte sintered at 1500?°C for 5?h. So, The Gd3+ and Fe3+ co-doped cerium oxide would be an excellent candidate electrolyte for ILT SOFCs due to its prominent sintering performance and enhanced electrical conductivity. 相似文献
78.
Yang Yang Hua Hao Lin Zhang Cheng Chen Zhiping Luo Zhen Liu Zhonghua Yao Minghe Cao Hanxing Liu 《Ceramics International》2018,44(10):11109-11115
BaTi1-xCaxO3-x [BTC100x] ceramics were synthesized via solid-state reaction method. Effect of Ca substitution on the structure, electrical and dielectric properties of BTC100x ceramics was systematically investigated. Calcined BTC100x powders were in tetragonal phase when x?≤?0.01, whereas transformed to cubic at x?>?0.01. Additionally, the diffraction peak (200) shifted to lower angles with increasing x, indicating increased unit cell volume. Meanwhile, Ba0.97Ca0.03TiO3 [BC3T] ceramic was prepared and studied, to compare with BaTi0.97Ca0.03O2.97 (BTC3). It was found that pure BaTiO3 [BT] and BC3T ceramics had the similar structural and dielectric properties, whereas BTC3 ceramic showed much difference,XRD patterns, Raman spectrum, impedance spectra and dielectric-temperature spectra provided strong evidence of Ca2+ substitution at Ti site in BT lattice. Finally, BTC100x ceramics were produced and dielectric properties were investigated. With increasing x, the Curie temperature decreased from 128?°C (BT) to 42?°C (BTC5). 相似文献
79.
Bao-Jia Li Yong-Ying Wang Li-Jing Huang Hai-Di Cao Qinghua Wang Nai-Fei Ren Hongtao Ding 《Ceramics International》2018,44(18):22225-22234
An ultrasonic-vibration-assisted laser annealing method was developed to enhance the performance of fluorine-doped tin oxide (FTO) thin films. The influences of ultrasonic vibration, laser scan line overlapping rate (LOR) and laser spot overlapping rate (SOR) on surface morphology, FTO layer thickness, RMS roughness, crystal structure and photoelectric properties of the FTO films were investigated. The results indicated that the presence of ultrasonic vibration during laser annealing could significantly enhance the film compactness, and using moderate LOR and SOR values resulted in significantly decreased FTO layer thicknesses and RMS roughnesses as well as slightly increased crystallite sizes, thus yielding significantly improved optical transmittance values and slightly enhanced electrical conductivity values. It was found that the optimal LOR and SOR values for ultrasonic-vibration-assisted laser annealing of the FTO films were 80% and 90%, respectively. The as-obtained film possessed the best overall photoelectric property with an average transmittance (400–800?nm) of 85.9%, a sheet resistance of 8.7?Ω/sq and a figure of merit of 2.51?×?10–2 Ω–1. This work may be of great significance in terms of performance optimization of transparent conducting oxide (TCO) thin films. 相似文献
80.
The in-situ fabrication of an electron-blocking layer between the Ba-containing anode and the ceria-based electrolyte is an effective approach in suppressing the internal electronic leakage in ceria-based solid oxide fuel cell (SOFC). To improve the thickness of the electron-blocking layer and to research the effect of the layer thickness on the improvement of SOFC, a Ba-containing compound (0.6NiO-0.4BaZr0.1Ce0.7Y0.2O3-δ) modified by Y stabilized zirconia (YSZ) was employed as a composite anode in this research. SEM analyses demonstrated that the thickness of the interlayer can be simply controlled by regulating the proportion of YSZ at anode. The in-situ formed interlayer in the cell with the anode modified by 20?mol% YSZ possesses a thickness of 0.9?µm which is more suitable for the cell achieving an enhanced performance. 相似文献