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Electronic Commerce Research - We consider a platform providing free content for users and earning profit from the sale of advertising. The platform can collect and analyze personal data to... 相似文献
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采用缓冲溶液法制备出NiO—GDC复合粉末,该粉末压制、烧结后再经氰气气氛还原得到Ni—GDC金属陶瓷阳极。使用XRD,TEM,SEM对NiO—GDC和Ni—GDC的物相、形貌进行了观察分析,测定了阳极还原前后的相对密度、总孔隙率及开孔隙率。实验结果表明,由于NiO转变为Ni,有O的火上,使得还原后试样的相对密度明显下降,而孔隙率由15.4%提高到29.6%,且开孔隙率达到23.1%,可满足阳极作为燃料扩散通道的作用。多孔结构的Ni—GDC金属陶瓷阳檄有望成为中混固体氧化物燃料电池的阳极材料。 相似文献
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Bing Zheng Yuchen Yue Jianling Ni Xucong Zhou Yongrui He Xiaoman Gui Han Shen Yanan Jing Jince Zhao Jianqi Zhang Yuan Zhang Jingxia Wang Lei Jiang Lijun Huo 《Advanced functional materials》2023,33(28):2300981
With the development of organic solar cells (OSCs), the high-performance and stable batch variance are becoming a new challenge for designing polymer donors. To obtain high photovoltaic performance, adopting polymers with high molecular weight as donors is an ordinary strategy. However, the high molecular weight need to subtly control the reaction time and state, inevitably caused batch-to-batch variations. Herein, a strategy of steric effect is applied to benzodifuran (BDF)-based polymer by introducing different positions of Cl atom, producing two polymers PBDFCl-1 and PBDFCl-2. The more twisted side chains conformation not only achieve the control of moderate molecular weight for PBDFCl-2, but also easily form molecular stacking through adopting BDF unit and maintain sufficient polymeric crystallinity. Due to the optimized stacking mode and good blend miscibility, PBDFCl-2-based device exhibitsa more elegant power conversion efficiency (PCE) of 17.00% compared to PBDFCl-1-based device. This is the highest efficiency record for BDF-based binary OSCs. Meanwhile, the PCE device variation of the different molecular weights for PBDFCl-2 is little, indicating the reduction of the batch variation. Therefore, smartly using steric effect of Cl atom in strong crystalline BDF unit can form efficient molecular stacking regulations and realize the coordination of high-performance and stable batch variance. 相似文献
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Yongrui?QinEmail author Quan?Z.?Sheng Nickolas?J.?G.?Falkner Lina?Yao Simon?Parkinson 《World Wide Web》2017,20(5):915-937
Since today’s real-world graphs, such as social network graphs, are evolving all the time, it is of great importance to perform graph computations and analysis in these dynamic graphs. Due to the fact that many applications such as social network link analysis with the existence of inactive users need to handle failed links or nodes, decremental computation and maintenance for graphs is considered a challenging problem. Shortest path computation is one of the most fundamental operations for managing and analyzing large graphs. A number of indexing methods have been proposed to answer distance queries in static graphs. Unfortunately, there is little work on answering such queries for dynamic graphs. In this paper, we focus on the problem of computing the shortest path distance in dynamic graphs, particularly on decremental updates (i.e., edge deletions). We propose maintenance algorithms based on distance labeling, which can handle decremental updates efficiently. By exploiting properties of distance labeling in original graphs, we are able to efficiently maintain distance labeling for new graphs. We experimentally evaluate our algorithms using eleven real-world large graphs and confirm the effectiveness and efficiency of our approach. More specifically, our method can speed up index re-computation by up to an order of magnitude compared with the state-of-the-art method, Pruned Landmark Labeling (PLL). 相似文献
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特高压直流输电阀控动模试验系统设计 总被引:1,自引:0,他引:1
针对近年国内特高压直流输电工程中换流阀控制设备的实际运行工况,设计了一套完整的特高压直流输电工程阀控动模试验系统,整个试验系统包括整流侧换流阀、整流侧阀控(valve control equipment,VCE)、逆变侧换流阀、逆变侧VCE、控制与监视后台系统.该试验系统直接采用工程用晶闸管来搭建微型换流阀,相比实际工程用换流阀,减少了每个单阀的晶闸管数量,其他换流阀设计参数与实际工程相同,相较于采用实时数字仿真(real-time digital simulator,RTDS)系统模拟换流阀参数的方式,更有利于换流阀及输电线路参数的精确获取与处理,对阀控功能的验证更加有效.最后对许继集团研制的VCE800阀控系统进行了试验,验证结果表明该阀控动模试验系统可以满足特高压直流工程阀控设备联调需要. 相似文献