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利用双金属接力催化策略合成环状有机化合物研究进展
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作者 许珈铭 向羽 +1 位作者 林维晟 苗志伟 《大学化学》 CAS 2024年第3期239-257,共19页
环状有机化合物在有机化学、药物化学和材料科学领域具有广泛应用,过渡金属催化的成环反应是制备多种环状化合物的有效方法之一。近年来科学家在研究单一过渡金属催化成环反应体系的基础上,进一步开发了金属/金属组合的接力催化体系,双... 环状有机化合物在有机化学、药物化学和材料科学领域具有广泛应用,过渡金属催化的成环反应是制备多种环状化合物的有效方法之一。近年来科学家在研究单一过渡金属催化成环反应体系的基础上,进一步开发了金属/金属组合的接力催化体系,双金属接力催化体系因其可以促进单一金属催化体系无法实现的转化而受到了极大的关注。本文综述了近五年来利用双金属接力催化策略实现环状有机化合物合成的研究进展,并对该领域的发展前景进行了展望。 展开更多
关键词 双金属接力催化 环状化合物 合成
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Axial Assembled Correspondence Network for Few-Shot Semantic Segmentation
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作者 Yu Liu Bin Jiang jiaming xu 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2023年第3期711-721,共11页
Few-shot semantic segmentation aims at training a model that can segment novel classes in a query image with only a few densely annotated support exemplars.It remains a challenge because of large intra-class variation... Few-shot semantic segmentation aims at training a model that can segment novel classes in a query image with only a few densely annotated support exemplars.It remains a challenge because of large intra-class variations between the support and query images.Existing approaches utilize 4D convolutions to mine semantic correspondence between the support and query images.However,they still suffer from heavy computation,sparse correspondence,and large memory.We propose axial assembled correspondence network(AACNet)to alleviate these issues.The key point of AACNet is the proposed axial assembled 4D kernel,which constructs the basic block for semantic correspondence encoder(SCE).Furthermore,we propose the deblurring equations to provide more robust correspondence for the aforementioned SCE and design a novel fusion module to mix correspondences in a learnable manner.Experiments on PASCAL-5~i reveal that our AACNet achieves a mean intersection-over-union score of 65.9%for 1-shot segmentation and 70.6%for 5-shot segmentation,surpassing the state-of-the-art method by 5.8%and 5.0%respectively. 展开更多
关键词 Artificial intelligence computer vision deep convolutional neural network few-shot semantic segmentation
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Mechanical Test and Meso-Model Numerical Study of Composite Rubber Concrete under Salt-Freezing Cycle
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作者 Mingkai Sun Yanan Wang +3 位作者 Pingwei Jiang Zerong Song Zhan Gao jiaming xu 《Journal of Renewable Materials》 SCIE EI 2023年第2期643-668,共26页
A composite rubber concrete(CRC)was designed by combining waste tire rubber particles with particle sizes of 3~5 mm,1~3 mm and 20 mesh.Taking the rubber content of different particle sizes as the influencing factors,t... A composite rubber concrete(CRC)was designed by combining waste tire rubber particles with particle sizes of 3~5 mm,1~3 mm and 20 mesh.Taking the rubber content of different particle sizes as the influencing factors,the range and variance analysis of the mechanical and impermeability properties of CRC was carried out by orthogonal test.Through analysis,it is concluded that the optimal proportion of 3~5 mm,1~3 mm,and 20 mesh particle size composite rubber is 1:2.5:5.5 kinds of CRC and 3 kinds of ordinary single-mixed rubber concrete(RC)with a total content of 10%~20%were designed under this ratio,and the salt-freezing cycle test was carried out with a concentration of 5%Na 2 SO4 solution.The physical and mechanical damage laws during 120 salt-freezing cycles are obtained,and the corresponding damage prediction model is established according to the experimental data.The results show that:on the one hand,the composite rubber in CRC produces a more uniform“graded”structure,forms a retractable particle group,and reduces the loss of mechanical properties of CRC.On the other hand,colloidal particles with different particle sizes are used as air entraining agent to improve the pore structure of concrete and introduce evenly dispersed bubbles,which fundamentally improves the durability of concrete.Under the experimental conditions,the CRC performance is the best when the overall content of composite rubber is 15%. 展开更多
关键词 Waste rubber composite rubber concrete orthogonal test mechanical properties DURABILITY
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低温烟气脱硝催化剂制备工艺及性能探究 被引量:2
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作者 徐家明 皇甫林 +4 位作者 史玉婷 郭洪范 高士秋 李长明 余剑 《过程工程学报》 CAS CSCD 北大核心 2022年第7期863-872,共10页
为了满足低温脱硝催化剂工业化的需求,对以相同组成的氧化物粉末、工业偏钛酸、水热偏钛酸为前驱体制备的脱硝催化剂的催化性能进行了考察,并利用X射线衍射、N2吸附-脱附、热重分析、机械强度等手段对催化剂的表面结构及性质进行表征分... 为了满足低温脱硝催化剂工业化的需求,对以相同组成的氧化物粉末、工业偏钛酸、水热偏钛酸为前驱体制备的脱硝催化剂的催化性能进行了考察,并利用X射线衍射、N2吸附-脱附、热重分析、机械强度等手段对催化剂的表面结构及性质进行表征分析。结果表明,随焙烧温度升高,各催化剂的活性先升高后降低,催化剂以水热偏钛酸为原料制备的催化剂(催化剂C)更适宜于工业应用,其拥有较好的低温活性、抗压强度及成型率;经过550℃焙烧10 h后催化剂的纵向抗压强度为1.06MPa,在250℃时NO转化率为97.79%。此外,对该催化剂进行脱硝活性评价及宏观动力学分析并考察了1~3 m/s气速下催化剂活性在不同烟气温度下的脱硝性能,结果表明,随气速增加催化剂的脱硝性能逐渐降低;根据Eley-Rideal机理,建立动力学方程,推算出该催化剂的反应速率常数k,并根据Arrhenius公式求得催化剂C的SCR脱硝反应活化能为32.15 kJ/mol,指前因子A为15.37×10^(3)L/(g·min),为实际工业烟气SCR脱硝系统设计提供参考。 展开更多
关键词 SCR 低温脱硝 选择性催化还原 蜂窝体催化剂 反应动力学
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