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81.
82.
可见光催化具有无污染、节能、优秀的官能团兼容性及良好的化学选择性,目前已经作为重要的有机合成手段之一,绿色化学在氧气与可见光的结合下得到了极大的发展,本文从白藜芦醇及其类似物的合成、芳构化反应和α位醛酮羰基的取代反应催化几个方面简略阐述了可见光催化需氧氧化在有机合成中的应用方式。 相似文献
83.
利用高频感应热氢等离子体强化还原制备超细铜粉,考察了加料速率、还原氢气流量、氢气分布位置、反应区空间、冷却温度等因素对铜粉颗粒性能的影响,对制备的铜粉颗粒进行氧含量、XRD晶体结构、松装密度、粒度分布和比表面积的表征。结果表明,优化的工艺条件为反应区内径100 mm,加料速率4 g/min,淬火气氩气气量500 L/h,氢气气量500 L/h并通入少量载气,由氢等离子电离产生的氢自由基可强化反应实现瞬时还原,不仅可控制铜粉形貌,还能有效控制铜粉颗粒大小;利用该方法制备出粒径分布100?200 nm、分散性好的超细球形铜粉颗粒。该方法操作简便、产品纯度高、气氛可控、对环境污染小。 相似文献
84.
AbstractWith the rapid progress of information technologies, cars have been made increasingly intelligent. This allows cars to act as cognitive agents, i.e., to acquire knowledge and understanding of the driving habits and behavioral characteristics of drivers (i.e., driving behavioral fingerprint) through experience. Such knowledge can be then reused to facilitate the interaction between a car and its driver, and to develop better and safer car controls. In this paper, we propose a novel approach to extract the driver’s driving behavioral fingerprints based on our conceptual framework Experience-Oriented Intelligent Things (EOIT). EOIT is a learning system that has the potential to enable Internet of Cognitive Things (IoCT) where knowledge can be extracted from experience, stored, evolved, shared, and reused aiming for cognition and thus intelligent functionality of things. By catching driving data, this approach helps cars to collect the driver’s pedal and steering operations and store them as experience; eventually, it uses obtained experience for the driver’s driving behavioral fingerprint extraction. The initial experimental implementation is presented in the paper to demonstrate our idea, and the test results show that it outperforms the Deep Learning approaches (i.e., deep fully connected neural networks and recurrent neural networks/Long Short-Term Memory networks). 相似文献
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86.
通过力学性能测试得到发泡硅橡胶应力应变曲线,结合Ogden(Foam) 3阶超弹本构模型,建立发泡硅橡胶静密封系统的有限元仿真模型,得到大压缩量下发泡硅橡胶的von Mises应力及接触压力分布情况。仿真结果表明:大压缩量下发泡硅橡胶对称中心线位置的von Mises应力、接触压力值较大,在橡胶边缘和靠近限位环处接触应力数值有突增。开展140℃热空气老化试验,测定老化后发泡硅橡胶应力应变曲线,结合有限元仿真模型分析发泡硅橡胶老化后von Mises应力、接触压力的变化规律。结果表明:经过热空气老化后,在一定载荷下发泡硅橡胶等效应力和接触压力均呈增大的趋势。 相似文献
87.
Chenglong Zhang Jingming Fei Lei Guo Jianxing Yu Binbin Zhang Zheng Yan Fuxing Ye 《Ceramics International》2018,44(8):8818-8826
LaPO4 powders were produced by a chemical co-precipitation and calcination method. The ceramic exhibited a monazite structure, kept phase stability at 1400?°C for 100?h, and had low thermal conductivity (~ 1.41?W/m?K, 1000?°C). LaPO4/Y2O3 partially stabilized ZrO2 (LaPO4/YSZ) double-ceramic-layer (DCL) thermal barrier coatings (TBCs) were fabricated by air plasma spray. The LaPO4 coating contained many nanozones. Thermal cycling tests indicated that the spallation of LaPO4/YSZ DCL TBCs initially occurred in the LaPO4 coating. The failure mode was similar to those of many newly developed TBCs, probably due to the low toughness of the ceramics. LaPO4/YSZ DCL TBCs were highly resistant to V2O5 corrosion. Exposed to V2O5 at 700–900?°C for 4?h, La(P,V)O4 formed as the corrosion product, which had little detrimental effect on the coating microstructure. At 1000?°C for 4?h, a minor amount of LaVO4 was generated. 相似文献
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89.
Chao Wen Alexander G. Banshchikov Yury Y. Illarionov Werner Frammelsberger Theresia Knobloch Fei Hui Nikolai S. Sokolov Tibor Grasser Mario Lanza 《Advanced materials (Deerfield Beach, Fla.)》2020,32(34):2002525
Mechanically exfoliated 2D hexagonal boron nitride (h-BN) is currently the preferred dielectric material to interact with graphene and 2D transition metal dichalcogenides in nanoelectronic devices, as they form a clean van der Waals interface. However, h-BN has a low dielectric constant (≈3.9), which in ultrascaled devices results in high leakage current and premature dielectric breakdown. Furthermore, the synthesis of h-BN using scalable methods, such as chemical vapor deposition, requires very high temperatures (>900 °C) , and the resulting h-BN stacks contain abundant few-atoms-wide amorphous regions that decrease its homogeneity and dielectric strength. Here it is shown that ultrathin calcium fluoride (CaF2) ionic crystals could be an excellent solution to mitigate these problems. By applying >3000 ramped voltage stresses and several current maps at different locations of the samples via conductive atomic force microscopy, it is statistically demonstrated that ultrathin CaF2 shows much better dielectric performance (i.e., homogeneity, leakage current, and dielectric strength) than SiO2, TiO2, and h-BN. The main reason behind this behavior is that the cubic crystalline structure of CaF2 is continuous and free of defects over large regions, which prevents the formation of electrically weak spots. 相似文献
90.