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11.
Yue-Ming?Li Wen?ChenEmail author Qing?Xu Jing?Zhou Hua-Jun?Sun Mei-Song?Liao 《Journal of Electroceramics》2005,14(1):53-58
The ternary lead-free piezoelectric ceramics system of (1 – x) [0.88Na0.5Bi0.5TiO3-0.12K0.5Bi0.5TiO3] – xNaNbO3(x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by conventional solid state reaction method. The crystal structure, dielectric, piezoelectric properties and P-E hysteresis loops were investigated. The crystalline structure of all compositions is mono-perovskite phase ascertained by XRD, and the lattice constant was calculated from the XRD data. Temperature dependence of dielectric constant r and dissipation factor tan measurement revealed that all compositions experienced two phase transitions: from ferroelectric to anti-ferroelectric and from anti-ferroelectric to paraelectric, and these two phase transitions have relaxor characteristics. Both transition temperatures Td and Tm are lowered due to introduction of NaNbO3. P-E hysteresis loops show that 0.88Na0.5Bi0.5TiO3-0.12K0.5Bi0.5TiO3 ceramics has the maximum Pr and Ec corresponding to the maximum values of electromechanical coupling factor Kp and piezoelectric constant d33. The piezoelectric constant d33 and electromechanical coupling factor Kp decrease a little, while the dielectric constant 33T/0 improves much more when the concentration of NaNbO3 is 8 mol%. 相似文献
12.
针对监督分类中的特征选择问题, 提出一种基于量子进化算法的包装式特征选择方法. 首先分析了现有子集评价方法存在过度偏好分类精度的缺点, 进而提出基于固定阈值和统计检验的两种子集评价方法. 然后改进了量子进化算法的进化策略, 即将整个进化过程分为两个阶段, 分别选用个体极值和全局极值作为种群的进化目标. 在此基础上, 按照包装式特征选择遵循的一般框架设计了特征选择算法. 最后, 通过15个UCI数据集分别验证了子集评价方法和进化策略的有效性, 以及新方法相较于其它6种特征选择方法的优越性. 结果表明, 新方法在80%以上的数据集上取得相似甚至更好的分类精度, 在86.67%的数据集上选择了特征个数更小的子集. 相似文献
13.
知识图谱补全能让知识图谱变得更加完整.现有的知识图谱补全工作大多会假设知识图谱中的实体或关系有充足的三元组实例.然而,在通用领域,存在大量长尾三元组;在垂直领域,较难获得大量高质量的标注数据.本文针对这一问题,提出了一种基于知识协同微调的低资源知识图谱补全方法.本文通过已有的结构化知识来构造初始的知识图谱补全提示,并提出一种协同微调算法来学习最优的模板、标签和模型的参数.本文的方法同时利用了知识图谱中的显式结构化知识和语言模型中的隐式事实知识,且可以同时应用于链接预测和关系抽取两种任务.实验表明,本文的方法在3个知识图谱推理数据集和5个关系抽取数据集上都取得了目前最优的性能. 相似文献
14.
Kailong Hu Tingting Yu Yanyi Zhang Xiaorong Lin Yilu Zhao Guoqiang Xie Xingjun Liu Xi Lin Jun-ichi Fujita Hua-Jun Qiu Yoshikazu Ito 《Advanced functional materials》2021,31(38):2103632
Catalyzing oxygen reduction reaction (ORR) and accelerating oxygen diffusion are two key challenges for the requirements of the cathode catalysts in the metal-air batteries. A promising strategy for improving both ORR performance and mass diffusion simultaneously is to build carbon-based catalysts with ORR-active chemical dopants and 3D interconnected porosity. Herein, a 3D nanoporous N-doped carbon with bicontinuous porosity and interconnected open-pore channels is reported, which is prepared by a polyaniline-assisted template method. The polyaniline can efficiently inhibit the surface diffusion-caused template coarsening, achieving a small pore size of 35 nm. The small porous morphology gives rise to a high N-dopant concentration up to 7.20 at.%, which in turn exhibits a commercial Pt/C-comparable ORR performance together with satisfied durability in alkaline media. Using these nanoporous carbon catalysts as air electrodes, an all-solid-state flexible Al-air battery is assembled with the measured maximum power density reaching 130.5 mW cm−2, as compared to 106.2 mW cm−2 when the commercial Pt/C standard is used. This study provides an efficient method to synthesize 3D N-doped carbon with bicontinuous nano-sized pore channels for wide-ranging applications in portable and flexible devices. 相似文献
15.
The recycling technology of photocatalyst powdery has hardly been mature in the photocatalytic ox-idation so far.In this work,the hollow TiO2 microspheres with ... 相似文献
16.
Jin-Jin Zhao Xiao Su Zhou Mi Ying Zhang Yan-Jun Hu Hua-Jun Guo Yi-Nan Jiao Yu-Xia Zhang Yan Shi Wei-Zhong Hao Jing-Wei Wu Yi Wang Cun-Fa Gao Guo-Zhong Cao 《稀有金属(英文版)》2022,(1):96-105
Organic–inorganic hybrid perovskite solar cells,one of the most promising photovoltaic devices,have made great progress in their efficiency and preparation technology.In this study,uniform,highly conductive LinNiOx(0≤n≤1;03+-Ni2+ as the interfacial passivation.Depending on the amount of lithium doping,controlled interfacial oxidation was induced by Ni3+.The Li0.32NiOxinhibited charge recombination,reduced the defect density,and enhanced the photocurrent density.A maximum power conversion efficiency of 20.44%was obtained by Li0.32NiOx.Further,in the long-term,in-air stabilities of unencapsulated Lin-NiOx perovskite solar cells were demonstrated. 相似文献
18.
A gated viewing laser radar has an excellent performance in underwater low light level imaging,and it also provides a viable solution to inhibit backscattering.In this paper,a gated viewing imaging system according to the demand for real-time imaging is presented,and then the simulation is used to analyze the performance of the real-time gated viewing system.The range accuracy performance is limited by the slice number,the width of gate,the delay time step,the initial delay time,as well as the system noise and atmospheric turbulence.The simulation results indicate that the highest range accuracy can be achieved when the system works with the optimal parameters.Finally,how to choose the optimal parameters has been researched. 相似文献
19.
采用等离子体增强化学气相沉积法制备了具有纳米结构的碳化钨薄膜, 采用XRD、EDS、SEM方法表征了薄膜的表面形貌、化学组成和物相结构. 这种碳化钨纳米晶薄膜具有巨大的电化学比表面积、很好的电催化活性和电化学稳定性. 通过测试和计算表明, 几何面积为1cm2碳化钨薄膜/泡沫镍电极、碳化钨薄膜/镍电极的电化学比表面积分别为83.21和64.13cm2; 该薄膜电极材料的a值为0.422~0.452V, 接近低超电势材料; 析氢交换电流密度为4.02~4.22×10-4A/cm2; 当超电势为263mV时, 其析氢反应的活化能为45.62~45.77kJ/mol. 相似文献
20.