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991.
Yean‐Ren Hwang 《中国工程学刊》2013,36(5):635-639
Abstract It is well known that using differential geometric methods, the reachability of nonlinear systems can be checked via Lie algebra. Normally, the resultant checking condition is state dependent and requires complicated recursive Lie bracket operations. In this paper, it is shown that for dyadic bilinear systems, the reachability property is actually state independent, and hence a global property of the system. Specifically, it is proved that the Lie algebra condition is equivalent to the rank conditions of two constant matrices. As examples, the reachability of two real‐world systems is examined through the new checking condition. 相似文献
992.
Mahboubeh Kiani Zitani Touradj Ebadzadeh Sara Banijamali Reza Riahifar Christian Rüssel Tilman Zscheckel Haishen Ren 《Ceramics International》2018,44(4):4016-4026
In the present research, the Li2ZnTi3O8(LZT) ceramics were synthesized throughout solid-state ceramic processing, then mixed with bismuth borate (BiBO) glass prepared based on conventional melt quenching method. Wetting behavior of BiBO glass on the LZT ceramic substrate was monitored by hot stage microscopy. Afterward, dielectric LZT ceramics containing different amounts of BiBO glass (0.25–6 wt%) were sintered at various temperatures. X-ray diffraction and electron back scatter diffraction examinations revealed the presence of two crystalline phases of Li2ZnTi3O8 and Bi2Ti2O7. The maximum value of relative density (above 95%) was obtained in the case of specimens contained more than 5 wt% glass. The microwave dielectric properties of the finally sintered BiBO glass containing LZT ceramics were as follows: dielectric constant (εr) = 21.44–25.09, quality factor (Q × f) = 10839–54708 GHz and temperature coefficient of resonant frequency (τf) = (? 15.58) ? (? 12.86)ppm/°C. 相似文献
993.
The adhesion of a punch to a linear elastic, confined layer is investigated. Numerical analysis is performed to determine the equivalent elastic modulus in terms of layer confinement. The size of the layer relative to the punch radius and its Poisson’s ratio are found to affect the layer stiffness. The results reveal that the equivalent modulus of a highly confined layer depends on its Poisson’s ratio, whereas, in contrast, an unconfined layer is only sensitive to the extent of the elastic film. The solutions of the equivalent modulus obtained from the simulations are fitted by an analytical function that, subsequently, is utilized to deduce the energy release rate for detachment of the punch via linear elastic fracture mechanics. The energy release rate strongly varies with layer confinement. Regimes for stable and unstable crack growth can be identified that, in turn, are correlated to interfacial stress distributions to distinguish between different detachment mechanisms. 相似文献
994.
995.
Kai Liang Saimeng Jin Hengzhi Chen Jingzheng Ren Weifeng Shen Shun'an Wei 《中国化学工程学报》2020,28(2):518-525
Coal fly ash is an industrial solid waste generated from coal preparation during the processing and cleaning of coal for electric power generation. Comprehensive investigation on the reutilization of waste heat of activated coal fly ash is of great economic significance. The method of recovering the waste heat, proposed in this study,is the transfer of heat from activated coal fly ash to gas with the movement of air using the packed bed, providing valuable energy sources for preheating the raw coal fly ash to reduce the overall energy consumption. The investigation is carried on the heat transfer characteristics of gas–solid(activated coal fly ash) phases and air temperature fields of the packed bed under some key conditions via computational fluid dynamics. A two dimensional geometry is utilized to represent key parts of packed bed. The distribution mechanism of the temperature field for gas phase is analyzed based on the transient temperature contours at different times. The results show that the obtained rule of gas–solid heat transfer can effectively evaluate the influences of operating parameters on the air temperature in the packed bed. Simultaneously, it is found that no temperature differences exist in the hot air at the outlet of the packed bed. The investigation provides guidance for the design and optimization of other similar energy recovery apparatuses in industries. 相似文献
996.
997.
Changbai Long Huiqing Fan Wei Ren Jinyan Zhao 《Journal of the European Ceramic Society》2019,39(14):4103-4112
This work reports the existence of double polarization hysteresis (P–E) loop in Aurivillius-phase ferroelectric Bi4Ti3O12 (BiT) and reveals dramatic influence of small compositional variations on the electrical properties of it. The double polarization hysteresis is a characteristic of the interaction of defects with domain walls. This characteristic becomes more pronounced in Bi-deficient and Mg-doped BiT due to an increase in oxygen vacancy concentration at the lattices. Normal and saturated P–E loop is recalled by Nb donor doping, and associated composition Bi4Ti2.97Nb0.03O12.015 (BiT-0.03Nb) shows high remnant polarization (Pr = 12.5 μC/cm2) and large field-induced strain (S33 = 5.6 × 10?4). In addition, this doping results in bulk conductivity (σb) of BiT decreasing dramatically and associated activity energy (Ea) increasing significantly. In contrast, high oxide ion conductivity is induced with Mg2+ acceptor doping, and at 600 °C the optimum composition has ionic conductivity of ?0.65 × 10?2 S cm?1 in the bulk. 相似文献
998.
Xinghong Duo Lingchuang Bai Jun Wang Jintang Guo Xiangkui Ren Shihai Xia Wencheng Zhang Abraham Domb Yakai Feng 《Frontiers of Chemical Science and Engineering》2021,15(1):220-220
The authors regret that there was an error in our publication.Considering Lingchuang Bai made great contributions to this work,Xinghong Duo and Lingchuang Bai should be co-first authors,but there was no statement that“Xinghong Duo and Lingchuang Bai contributed equally to this work”.The authors would like to apologize for any inconvenience caused. 相似文献
999.
Cheng-Cai Zhao Rui-Lin Lin Min-Min Dai Xin Xu Lin-Lin Zhu Jia-Xiang Xue Jian-Han Zhai Hai-Bin Ma Wei-Ming Guo Hua-Tay Lin Qi-Sen Ren Ye-Hong Liao 《Journal of the European Ceramic Society》2021,41(3):2157-2161
Joining of SiC ceramics was successfully achieved at a relatively low temperature of 1500 °C without any pressure using pure polycarbosilane (PCS) as the joining material, which was distributed homogenously on the surface of SiC monolith through a screen printing method. The XRD pattern shows that the pyrolysis product of PCS is single-phase SiC. The interlayer thickness of the SiC joint is approximately 2 μm. This ultra-thin interlayer with lower possibility of the existence of defects contributes to the average shear strength of 105.8 ± 10.4 MPa, higher than that of other works using other preceramic polymers to the best of our knowledge. Due to the simplicity, low cost and high joining strength, the screen printing method using PCS as the joining material has good practicality in SiC ceramics joining. 相似文献
1000.