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排序方式： 共有2399条查询结果，搜索用时 15 毫秒
41.
剥离石墨(EG)是一种很有前途的吸油剂,也是制备柔性石墨薄膜(FGFs)的中间产品.传统的乙二醇生产技术已成为节能减排的重要挑战.提出了一种简单有效的制备剥离石墨的方法,探讨了制备过程中H2SO4和H2O2的用量、室温剥离石墨(RTEG)的制备温度等影响因素.与高温剥离法(HTEG)相比,室温剥离石墨结构均匀,体积和表... 相似文献
42.
Bayesian Neural Networks for Uncertainty Analysis of Hydrologic Modeling: A Comparison of Two Schemes 总被引：2，自引：0，他引：2
Bayesian Neural Networks (BNNs) have been shown as useful tools to analyze modeling uncertainty of Neural Networks (NNs). This research focuses on the comparison of two BNNs. The first BNNs (BNN-I) use statistical methods to describe the characteristics of different uncertainty sources (input, parameter, and model structure) and integrate these uncertainties into a Markov Chain Monte Carlo (MCMC) framework to estimate total uncertainty. The second BNNs (BNN-II) lump all uncertainties into a single error term (i.e. the residual between model prediction and measurement). In this study, we propose a simple BNN-II, which uses Genetic Algorithms (GA) and Bayesian Model Averaging (BMA) to calibrate Neural Networks with different structures (number of hidden units) and combine the predictions from different NNs to derive predictions and uncertainty estimation. We tested these two BNNs in two watersheds for daily and monthly hydrologic simulations. The BMA based BNNs (BNN-II) developed here outperforms BNN-I in the two watersheds in terms of both accurate prediction and uncertainty estimation. These results indicate that, given incomplete understanding of the characteristics associated with each uncertainty source and their interactions, the simple lumped error approach may yield better prediction and uncertainty estimation. 相似文献
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44.
Xiaxin Gao;Jin Li;Wenqiang Yuan;Shuzhen Yan;Xiaodong Ma;Tiantian Li;Xuesong Jiang; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(44):2403099
Bottom-up patterning technology plays a significant role in both nature and synthetic materials, owing to its inherent advantages such as ease of implementation, spontaneity, and noncontact attributes, etc. However, constrained by the uncontrollability of molecular movement, energy interaction, and stress, obtained micropatterns tend to exhibit an inevitable arched outline, resulting in the limitation of applicability. Herein, inspired by auxin's action mode in apical dominance, a versatile strategy is proposed for fabricating precision self-organizing micropatterns with impressive height based on polymerization-induced acropetal migration. The copolymer containing fluorocarbon chains (low surface energy) and tertiary amine (coinitiator) is designed to self-assemble on the surface of the photo-curing system. The selective exposure under a photomask establishes a photocuring boundary and the radicals would be generated on the surface, which is pivotal in generating a vertical concentration difference of monomer. Subsequent heating treatment activates the material continuously transfers from the unexposed area to the exposed area and is accompanied by the obviously vertical upward mass transfer, resulting in the manufacture of a rectilinear profile micropattern. This strategy significantly broadens the applicability of self-organizing patterns, offering the potential to mitigate the complexity and time-consuming limitations associated with top-down methods. 相似文献
45.
Gongshuo Yu Xuesong Li Tao Bai Xiaobing He Jinlong Fan Jianbo Shang 《Journal of Nuclear Science and Technology》2020,57(5):599-606
ABSTRACTIn view of the complexity of current detection efficiency calibration of radioactive gas sources, a method using solid planar sources to be equivalent to gas sources was studied. For the 50 mL gas source box, an optimal equivalent scheme was selected by Monte Carlo Simulations. Then, the full-energy-peak efficiency curve of gas sources at the measurement position of 25 cm, with source-to-detector distance of 25 cm, was fitted by measuring solid planar sources with known activity. To verify the accuracy of the efficiency curve, 41Ar, 133Xe and 87Kr gases were produced and determined by length-compensated method. Then, their full-energy-peak efficiencies at 25 cm position away from the detector were directly calibrated. The percentage efficiency deviations between interpolation from the efficiency curve and direct calibration are all less than 2.5%, which proves the accuracy of the equivalent method. This calibration method is a general one and can be also used for some other radioactive sample measurements, such as non-destructive analysis of gaseous fission product samples with a suitable source-to-detector distance. 相似文献
46.
Chao Liu Deze Zeng Hong Yao Xuesong Yan Linchen Yu Zhangjie Fu 《Concurrency and Computation》2020,32(3)
Graph data processing has been widely applied in a variety of domains such as industry, science, social network, and so on. It therefore has stimulated many efforts devoted to this area. To embrace the fast development trend of big graph data, graph data processing based on Pregel‐like systems has been regarded as one of the most promising ways and has widely attracted the attention of researchers. However, it still remains in its early stage and there still exist many challenges. In Pregel, the superstep synchronization is time consuming as the graph data iteration operation requires multiple synchronizations. Furthermore, the graph data partition strategy adopted by Pregel fails to support load balancing, therefore causing the increase of network I/O overhead as the scale of graph data grows. To address these issues, this paper presents an efficient computational framework for graph data processing based on the bulk synchronous parallel model. The global synchronization control mechanism is improved by determining the start time of the next round of superstep through counting the number of global message files. Furthermore, an improved graph data partition mechanism based on a balanced hash method is proposed to reduce the communication overhead between different partitions of sub‐graph computational tasks. We also re‐design the PageRank algorithm to verify the effectiveness of the proposed framework. Experimental results on different real‐world datasets verify the efficiency of our proposed framework as it outperforms Giraph (an open source Pregel‐like system) by 58%−69%, and achieves 10×−17× performance improvement over Hadoop. 相似文献
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48.
本文采用一种新的数字图像相关方法测量带有半导体电热膜的远红外陶瓷热胀系数.该方法将有限元的位移模式引入,更适合于微细观领域的高精度测量,可以得到热胀系数随温度变化的曲线.结果表明,陶瓷基体和电热膜均表现出各向异性的热膨胀.在基体和膜热胀系数数值较接近的方向,降温时膜收缩而基体继续膨胀;在基体和膜的热胀系数变化规律一致的方向上,数值上膜的热胀系数要比基体的热胀系数大得多.若已知陶瓷基体和电热膜的应力应变本构关系,就可以根据测试结果计算陶瓷基体与电热膜之间的热应力及残余应力. 相似文献
49.
Linzhi Zhang Hongjie Xu Xiaodong Ma Zixing Shi Jie Yin Xuesong Jiang 《Advanced Materials Interfaces》2016,3(15)
The interaction between building blocks in the polymer hybrids plays an important role in their performance and functions. Herein, a novel multifunctional polymer hybrid with tunable charge transfer (CT) interaction between π‐electron‐poor naphthalenediimide (NDI) containing polyimide (PI) and π‐electron‐rich anthracene (AN) ended polyhedral oligomer silsesquioxane (POSS‐AN) is reported (name the polymer hybrid “PI@POSS‐AN”), in which the presence of CT interaction between NDI and AN and its controllable feature are confirmed by UV−vis and fluorescence spectra. A new absorption band at 500 nm in the visible region appears and the emission maxima of the CT complexes are distinctly red‐shifted to 645 nm, while the fluorescence of NDI (493 nm) and AN (481 nm) are significantly quenched in the polymer hybrids. The resulting hybrid films are transparent and homogeneous, exhibit the enhanced thermal and mechanical performance with the increasing content of POSS‐AN. Thanks to the reversible photodimerization of AN, CT interaction between NDI and AN can be on‐off controlled in situ by UV light and heating, and rewritable fluorescence micro‐patterns with red and green emission can be obtained. In addition, the cross‐linked polymer hybrids possess healability and reprocessing performance. 相似文献
50.
Yingjie Luo Yiwei Zhang Cimin Tao Hongfei Ni Xuesong Liu Yong Chen Yongjiang Wu Hang Song Tengfei Xu 《International journal of molecular sciences》2022,23(20)
Imidazolium-based ionic liquids are wildly used in natural product adsorption and purification. In this work, one typical polymeric ionic liquid (PIL) was synthesized by using L-proline as the anion, which exhibited excellent adsorption capacity toward tea polyphenol epigallocatechin gallate (EGCG). The adsorption conditions were optimized with the response surface method (RSM). Under the optimum conditions, the adsorption capacity of the PIL for EGCG can reach as high as 552 mg/g. Dynamics and isothermal research shows that the adsorption process of EGCG by the PIL particularly meets the quasi-second-order kinetic equation and monolayer adsorption mechanism. According to thermodynamic parameter analysis, the adsorption process is endothermic and spontaneous. The results of theoretical calculation by molecular docking also demonstrated the interaction mechanisms between EGCG and the ionic liquid. Considering the wide application of imidazolium-based ionic liquids in component adsorption and purification, the present study can not only be extended to other similar experimental mechanism validation, but also be representative for guiding the synthesis of PIL and optimization of adsorption conditions. 相似文献