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91.
According to the characteristics of fluid-structure interaction(FSI) in the process of metal bellows inflating to disperse bomblets,a 3D dynamical FSI model(W model) which describes the interaction between a viscous compressible flow and a structure undergoing large deformationis established.Then the dynamic characteristics of the metal bellows deformation, the changing law of the internal flow field and the motion law of the bombs are acquired.Where the internal pressure and bombs'' moving law are approximate to interior ballistic results, which indicates the W model established reasonably.Besides, considering gaps existing atthe bellows'' tow ends, the dynamical FSI modelcontaining gaps(Y model) is also built.The results of the W and Y models are compared and the results show that the existence of the gaps has little influence to the flow field and the stress distributionin the bellows,but obviously reduces the separation speed of the bomblets about 10%. 相似文献
92.
人口红利促进经济增长,但是城乡收入差距却不断扩大。从人口红利的两个显著特征,高劳动参与率和总抚养比的下降两个途径提出理论假说。以中国1993—2012年的第二三产业总比重、城乡人力资本投资差异和城乡收入差距的时间序列数据,构建VECM 模型。实证结果表明:城乡收入差距长期受到产业结构的变动和城乡人力资本投资差异的共同作用;在滞后期内,第二三产业总比重的增加导致城乡收入差距缩小,城乡人力资本投资差异的扩大将导致城乡收入差距扩大。 相似文献
93.
铁心电抗器气隙等效导磁面积计算 总被引:1,自引:0,他引:1
以一台实际干式带气隙铁心电抗器为例,建立电抗器的三维电磁场仿真模型,给出仿真模型内的基本假设和边界条件;采用有限元分析,计算出了不同气隙下铁心电抗器的电感值和磁路中的磁感应强度矢量图,并与部分实测数据相对比,验证了仿真模型与仿真结果的正确性.然后,以铁心电抗器的电感量为主要研究对象,定量计算在不同气隙与不同铁心直径下电抗器的电感值,给出了电感值随气隙和铁心直径的变化曲线并对其拟合及定性分析.最后,结合铁心电抗器计算公式和基本假设,推算出气隙处磁通等效导磁面积扩大系数,研究气隙等效导磁面积扩大系数随气隙和铁心直径的变化关系.所得结论可以为此类电抗器的设计计算提供一定的技术支持. 相似文献
94.
基于用多刚体来离散化柔性体的基本思想,以Adams为编程平台,对某苗床温室卷膜进行了建模与仿真。首先在Matlab中通过编程得到了卷膜所在螺旋线上多个均匀分布的离散点的坐标值,再通过数据文件传输到Adams,然后在Adams中编程创建了多片卷膜,并在卷膜之间施加转动副和接触力来模拟其相互关系。经过仿真寻找某片卷膜的质心位置及速度随时间变化的规律,结果表明本文提出的建模方法具有一定的可行性。 相似文献
95.
Zemin He Ping Yu Haiyang Wang Jianjing Gao Yang Zhao Haiquan Zhang Yuzhen Zhao Zongcheng Miao 《Journal of the American Ceramic Society》2021,104(9):4389-4397
Ferroelectric BaTiO3 was combined with Ag nanoparticles for piezocatalytic and photocatalytic viewpoints. Microstructural characterization (X-ray diffraction and electron microscopy images) revealed that the Ag was successfully bounded with BaTiO3. X-ray photoelectron spectrum also confirmed the presence of Ag. Further, its performance was examined for dye degradation under visible light (for photocatalysis) and ultrasonication (for piezocatalysis). In both the catalysis processes, there was a significant improvement in Ag-loaded BaTiO3 sample-based catalytic reactions. Catalytic performance was evaluated for multiple cycles and was found consistent. Scavenger tests were also performed to understand catalytic reactions. 相似文献
96.
Zhenya Wang Hao Guo De Ning Xiaobai Ma Lirong Zheng Dmitry Smirnov Kai Sun Dongfeng Chen Limei Sun Xiangfeng Liu 《Journal of the American Ceramic Society》2021,104(11):5934-5945
Li4Ti5O12 (LTO) attracts great interest due to the “zero strain” during cycles but the poor electronic and ionic conductivity critically impede the practical application. Herein, we report a synergy strategy of tuning localized electrons to shift Fermi level and band gap by Mg/Zr co-doping and oxygen vacancy incorporation, which significantly improves Li+ and electronic transport. More importantly, the intrinsic synergistic mechanism has been revealed by neutron diffraction, X-ray absorption spectra, and first-principles calculations. The “elastic effect” of lattice induced by Mg/Zr co-doping allows LTO to accommodate more oxygen vacancies to a certain degree without a severe lattice distortion, which largely improves the electronic conductivity. Mg/Zr co-doping and oxygen vacancy incorporation effectively enhanced the dynamic characteristics of LTO electrode, achieving the excellent rate performance (90 mAh/g at 20C) and cycle stability (96.9% after 500 cycles at 10C). First-principles calculations confirm Fermi level shifts to the conduction band, and the band gap becomes narrowed due to the synergistic modulation, and the intrinsic mechanism of the enhanced electronic and Li-ion conductivity is clarified. This study offers some insights into achieving the fast Li+ insertion/extraction by tuning the crystal and electronic structure with lattice doping and oxygen vacancy engineering. 相似文献
97.
98.
Cu对Al-Zn系a1/(a1+a2)边界走向的影响 总被引:1,自引:0,他引:1
对平衡处理(300℃~340℃)后的Al-Zn及Al-Zn加Cu合金a1相成分进行了电子探针微区分析。确定了Cu对a1 a2溶解度间隙形状,即a1/(a1 a2)边界走向的影响。该边界随着Cu含量的增加,向低Zn侧偏移,而不是此前所确定的向高Zn侧偏移。这一结果支持近年的热力学计算结果,溶解度间隙呈“隧道形”,而不支持根据实测相图推测的“钟罩形”。 相似文献
99.
100.
Hyung-Jun Chang Heung Nam Han Sang-Hoon Joo Kwang-Hee Lee Kyu Hwan Oh 《International Journal of Machine Tools and Manufacture》2007,47(10):1573-1582
The hot roll pressing of iron powder with several rotating speeds was carried out on a pilot-plant scale. From these experiments, it was confirmed that the surface temperature of roller was increased with increasing its rotating speed. It was also known that the heat transfer coefficient between the iron powder and the roller surface is closely related with the rotating speed of roller. These results were quantitatively described by using a mathematical model which was derived based on the steady-state heat transfer during hot roll pressing. In addition, the densification behavior of iron powder during the hot roll pressing was simulated by a finite element model based on the arbitrary Lagrangian and Eulerian (ALE) method and a yield criterion for metal powder. From these models, the maximum critical rotating speed of roller during the hot roll pressing, in which the roller could hold out against the thermal fracture, could be determined. 相似文献