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91.
Decoupled two‐grid finite element method for the time‐dependent natural convection problem I: Spatial discretization
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Tong Zhang JinYun Yuan ZhiYong Si 《Numerical Methods for Partial Differential Equations》2015,31(6):2135-2168
In this article, a decoupled two grid finite element method (FEM) is proposed and analyzed for the nonsteady natural convection problem using the coarse grid numerical solutions to decouple the nonlinear coupled terms, and the corresponding optimal error estimates are derived. Compared with the standard Galerkin FEM and the usual two‐grid FEM, our algorithm not only keeps good accuracy but also saves a lot of computational cost. Some numerical examples are provided to verify the performances of the decoupled two‐grid FEM. Both theoretical analysis and numerical experiments show the efficiency and effectiveness of the decoupled two‐grid FEM for the nonsteady natural convection problem. © 2015 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 2135–2168, 2015 相似文献
92.
D. Zhao T. Shi C. Chen Z. Si Q. Duan L. Shi 《Russian Journal of Coordination Chemistry》2014,40(4):224-231
Three Mn(II) complexes of [MnL(Bipy)(H2O)] n (I), [Mn3(Phen)2(HL)2(L)2]n (II), and [Mn(Phen)2(HL)(OH)] (III), where L = 4,4′-(2-acetylpropane-1,3-diyl)dibenzoic acid, Bipy = 2,2′-bipyridine, and Phen = 1,10-phenanthroline, were hydrothermally synthesized and characterized by single crystal X-ray diffractions, infrared spectroscopy, thermogravimetric analyses, and magnetic analyses. Complexes I and II are one dimensional (1D) coordination polymers which can form the supramolecules with the help of the intermolecular hydrogen bond interactions. Finally, the landé factors are simulated by magentochemical analysis to be 2.15 and 1.80 for I and II with S = 5/2, respectively. 相似文献
93.
Meng-Yue Jiang Li Yu Yi-Cheng Zhou Jing Jia Xue-Jian Si Wen-Wen Dong Zheng-Fang Tian Jun Zhao Dong-Sheng Li 《无机化学与普通化学杂志》2020,646(5):268-274
A novel three-dimensional (3D) d-f heterometallic metal-organic framework (MOF) formulated as [EuCd1.5L2(H2O)3] · 2H2O ( 1 ) [H3L = 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid] was successfully synthesized and characterized. Structural analysis displays that 1 features a 3D (3, 12)-connected framework constructed by [Eu2Cd3(tetrazole)4(COO)8] units. The powder X-ray diffraction measurement of 1 immersed in different solvents reveals that 1 possess good solvent stability. It is worth noting that 1 displays highly selective detection for ronidazole (RDZ) and 4-nitrophenol (4-NP) through luminescence quenching. The possible mechanism of luminescent sensing is also well discussed. 相似文献
94.
以3-异丙基苯乙酮(1)为原料,经3步反应合成了花青醛[3-(3-异丙基苯基)丁醛(4)],并优化了反应条件。确定合成3-(3-异丙基苯基)-2-丁烯酸乙酯(2)的最优条件为:n(1)/n(磷酰基乙酸三乙酯)/n(氢化钠)=5/6/6,于室温反应12 h,收率84.5%;合成3-(3-异丙基苯基)-1-丁醇(3)的最佳条件为:n(2)/n(硼氢化钠)/n(六水合二氯化钴)/n(二异丙基胺)=10/20/1/2,于55 ℃反应24 h,收率87.8%;合成4的最优条件为: n(3)/n(乙酸酐)/n(亚硝酸钠)=5/4/15,投料顺序为:乙酸酐、3、亚硝酸钠,反应时间为2 min,收率91.0%。产物结构经1H NMR, 13C NMR和MS(ESI)确证。 相似文献
95.
Yuxiang Chen Ke Gong Feng Jiao Xiulian Pan Guangjin Hou Rui Si Xinhe Bao 《Angewandte Chemie (International ed. in English)》2020,59(16):6529-6534
Despite significant progress achieved in Fischer–Tropsch synthesis (FTS) technology, control of product selectivity remains a challenge in syngas conversion. Herein, we demonstrate that Zn2+‐ion exchanged ZSM‐5 zeolite steers syngas conversion selectively to ethane with its selectivity reaching as high as 86 % among hydrocarbons (excluding CO2) at 20 % CO conversion. NMR spectroscopy, X‐ray absorption spectroscopy, and X‐ray fluorescence indicate that this is likely attributed to the highly dispersed Zn sites grafted on ZSM‐5. Quasi‐in‐situ solid‐state NMR, obtained by quenching the reaction in liquid N2, detects C2 species such as acetyl (‐COCH3) bonding with an oxygen, ethyl (‐CH2CH3) bonding with a Zn site, and epoxyethane molecules adsorbing on a Zn site and a Brønsted acid site of the catalyst, respectively. These species could provide insight into C?C bond formation during ethane formation. Interestingly, this selective reaction pathway toward ethane appears to be general because a series of other Zn2+‐ion exchanged aluminosilicate zeolites with different topologies (for example, SSZ‐13, MCM‐22, and ZSM‐12) all give ethane predominantly. By contrast, a physical mixture of ZnO‐ZSM‐5 favors formation of hydrocarbons beyond C3+. These results provide an important guide for tuning the product selectivity in syngas conversion. 相似文献
96.
Kai Wu Kang Li Sha Chen Ya‐Jun Hou Yu‐Lin Lu Jing‐Si Wang Mei‐Juan Wei Mei Pan Cheng‐Yong Su 《Angewandte Chemie (International ed. in English)》2020,59(7):2639-2643
A nanocage coupling effect from a redox RuII‐PdII metal–organic cage (MOC‐16) is demonstrated for efficient photochemical H2 production by virtue of redox–guest modulation of the photo‐induced electron transfer (PET) process. Through coupling with photoredox cycle of MOC‐16, tetrathiafulvalene (TTF) guests act as electron relay mediator to improve the overall electron transfer efficiency in the host–guest system in a long‐time scale, leading to significant promotion of visible‐light driven H2 evolution. By contrast, the presence of larger TTF‐derivatives in bulk solution without host–guest interactions results in interference with PET process of MOC‐16, leading to inefficient H2 evolution. Such interaction provides an example to understand the interplay between the redox‐active nanocage and guest for optimization of redox events and photocatalytic activities in a confined chemical nanoenvironment. 相似文献
97.
Si‐Hua Hou Adriana Y. Prichina Mengxi Zhang Guangbin Dong 《Angewandte Chemie (International ed. in English)》2020,59(20):7848-7856
To show the synthetic utility of the catalytic C?C activation of less strained substrates, described here are the collective and concise syntheses of the natural products (?)‐microthecaline A, (?)‐leubehanol, (+)‐pseudopteroxazole, (+)‐seco‐pseudopteroxazole, pseudopterosin A–F and G—J aglycones, and (+)‐heritonin. The key step in these syntheses involve a Rh‐catalyzed C?C/C?H activation cascade of 3‐arylcyclopentanones, which provides a rapid and enantioselective route to access the polysubstituted tetrahydronaphthalene cores presented in these natural products. Other important features include 1) the direct C?H amination of the tetralone substrate in the synthesis of (?)‐microthecaline A, 2) the use of phosphoric acid to enhance efficiency and regioselectivity for problematic cyclopentanone substrates in the C?C activation reactions, and 3) the direct conversion of serrulatane into amphilectane diterpenes by an allylic cyclodehydrogenation coupling. 相似文献
98.
99.
Nonlinear Dynamics - Intelligent fault diagnosis provides great convenience for the prognostic and health management of the rotating machinery. Recently, the multiscale diversity entropy has been... 相似文献
100.
Jian Jiao Min Chen Shengxin Sun Weijie Si Xiaobin Wang Weijie Ding Xincan Fu An Wang Chunlong Yang 《中国化学》2021,(2):323-329
To screen novel antifungal agents targeting the succinate dehydrogenase(SDH),a series of pyrazole-4-carbohydrazides were rationally designed,synthesized,and characterized under the guidance of the structures of succinate dehydrogenase inhibitors(SDHIs).Bioassay results in vitro indicated that most of the target compounds exhibited excellent activity against Rhizoctonia solani(R.solani),Fusarium graminearum(F.graminearum),Botrytis cinerea(B.cinerea)and Colletotrichum capsica(C.cinerea).Compounds 7d,7l,7t and 7x were identified as the most promoting candidates,and their anti-F.graminearum EC50 values were as low as 0.56,0.47,0.46 and 0.49μg/mL,respectively,presenting the similar antifungal activity as that of the commonly used fungicide carbendazim(0.43μg/mL).The 3D-QSAR models were built for a systematic structure-activity relationship profile to explore more potent pyrazole-4-carbohydrazides as novel fungicides.Molecular docking of 7d,7l and 7r with SDH was performed to reveal the binding modes in active pocket and analyze the interactions between the molecules and the SDH protein. 相似文献