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Decay of the 2D Periodic Stationary Viscous Surface Waves

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Acta Mathematica Sinica,English Series 2018年第12期34卷 1837-1862页

作者： yun Rui zheng School of Mathematical Sciences Qufu Normal University

We consider the evolution of viscous fluids in a 2D horizontally periodic slab bounded above by a free top surface and below by a fixed fiat bottom. This is a free boundary problem. The dynamics of the fluid are governed by the incompressible stationary Navier-Stokes equations under the influence of gravity and the effect of surface tension. We develop the global theory of solutions in low regularity Sobolev spaces for small data by nonlinear energy estimates.

关键词： Free boundary problems global existence Navier Stokes equations

Non-synchronous blade vibration analysis of a transonic fan

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Chinese Journal of Aeronautics 2023年第1期36卷 178-190页

作者： yun zheng Qingzhe GAO Hui YANG School of Energy and Power Engineering Beihang UniversityBeijing 100191China Jiangxi Research Institute Beihang UniversityNanchang 330096China

This study numerically investigates the aeromechanic behavior of a transonic fan model with a flat tip-leading-edge on the NASA rotor 67 test ***-passage unsteady calculations at a near stall operating point of 82%design speed show that the dominant frequencies of mass flow were not the harmonics of the rotor rotational frequency.A full-annulus fluid–structure interaction analysis was subsequently carried out to examine the unsteady flows and their interactions with blade *** results show that the modal displacement of the backward traveling seventh nodal diameter of the second torsion mode grew exponentially,which reveals that the blade vibration was *** vibration pattern indicates that the aerodynamic mode was resonant with the structural vibration *** the rotor tip,the circumferential vortical propagation induced by interactions among the main flow,tip leakage flow,and tip clearance vortex was the source of aerodynamic *** clarify the mechanism of the non-synchronous vibration,the coupling between aerodynamic disturbance and structural response,i.e.,aliasing,was *** frequency spectra of the fluctuating pressure show that an aerodynamic Back-ward Traveling Wave(BTW)was co-aliased to a structural BTW due to the propagation of the cir-cumferential *** correlation between the frequency and free convective speed of the aerodynamic disturbance determined the directions of aliasing.

关键词： Aerodynamic disturbance Aliasing Blade vibration Circumferential vortical propagation Traveling wave

Studies on the Quantitative Structure-activity Relationship of Substituted Biphenyls by Density Function Theory (DFT)

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Chinese Journal of Structural Chemistry 2007年第2期26卷 229-233页

作者： HAN Xiang-yun zheng Qing Department of Chemical Engineering YanchengInstitute of Technology Jiangsu 224003 China

Geometrical configurations of 16 substituted biphenyls were computed at the B3LYP/6-311G^＊＊ level with Gaussian 98 program. Based on linear solvation energy theory, lgKow as well as the structural and thermodynamic parameters obtained at this level was taken as theoretical descriptors, and corresponding equation predicting the toxicity of Daphnia magna （-lgEC5o） was thus obtained, in which three parameters were contained, i.e., n-octanol/water partition coefficients （lgKow）, dipole moment of the molecules（ μ） and entropy （S°）. For this equation, R^2 = 0.9582, q^2 = 0.8921 and SD = 0.102. The absolute t-scores of three variables are larger than the standard one in the confidence range of 95%, which confirms the creditability and stability of this model.

关键词： substituted biphenyl linear solvation energy theory,DFT method Daphnia magna toxicity

一株同步硝化反硝化菌株的筛选及其生物电化学脱氮性能研究

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南京农业大学学报 2025年第1期48卷 133-143页

作者：田瑞瑞付欢郑云黄新琦周俊雍晓雨南京工业大学生物与制药工程学院江苏南京211816 南京师范大学地理科学学院江苏南京210023

[目的]本文旨在获得具有高效脱氮性能的异养硝化-好氧反硝化(heterotrophic nitrification-aerobic denitrification,HN-AD)功能菌株,构建生物电化学-同步硝化反硝化(bio-electrochemical systems-simultaneous nitrification and denitrification,BES-SND)耦合系统,实现脱氮效率的提升。[方法]从活性污泥中筛选HN-AD菌株,鉴定后通过摇瓶试验分析其脱氮性能。然后进一步研究碳源、C/N、溶解氧等外界因素对菌株同步硝化反硝化性能的影响。将菌株接种到微生物燃料电池(microbial fuel cells,MFC)的生物阴极,分析低C/N条件下BES-SND体系的脱氮性能。[结果]从活性污泥中筛选出一株具有同步硝化反硝化性能的HN-AD菌株,命名为Alcaligenes aquatilis N3。确定该菌株发生SND反应的最适碳源为乙酸钠、C/N值为20、溶解氧为3.70 mg·L^(-1)。在BES-SND脱氮体系中,C/N值分别为2、4、6、8时,菌株*** N3的总氮去除率分别为20.51%、26.67%、37.76%和48.50%。在C/N=2的试验条件下,BES-SND系统的总氮去除速率在第5天仍为1.79 mg·L^(-1)·d^(-1)。[结论]在低碳环境下,*** N3菌株依然可以在BES-SND耦合脱氮体系中实现脱氮,降低了脱氮过程对碳源的依赖性,具有一定的实际环境应用潜力。

关键词：同步硝化反硝化异养硝化-好氧反硝化生物电化学低C/N值微生物燃料电池

Effect of Stitching on Plain and Open-hole Strength of CFRP Laminates

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Chinese Journal of Aeronautics 2012年第3期25卷 473-484页

作者： zheng yun CHENG Xiaoquan YASIR Baig School of Economics and Management Beihang University Beiiing l OO191. China School of Aeronautical Science and Engineering Beihang University Beijing 100191 China

Experimental and analytical investigation is conducted to explore the effects of stitching on plain （without hole） and open-hole compressive and tensile strength of uniweave T300/QY9512 laminates under different environmental conditions （20 ℃/dry and wet, 150 ℃/dry and wet）. Strength performance of stitched composite laminates is also studied using finite element analysis （FEA） model and compared with the experimental results to validate the model. It is found that under similar environmental conditions, the open-hole compressive strength of stitched laminate is decreased and open-hole tensile strength increased as compared to the unstitched laminates. Predicted tensile and compressive strengths are found to be in a good agreement with the test results and the relative error in all cases is less than 15%.

关键词： composite materials stitching finite element method resin film infusion hygrothermal

A field study of advanced municipal wastewater treatment technology for artificial groundwater recharge

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Journal of Environmental Sciences 2006年第6期18卷 1056-1060页

作者： PI yun-zheng WANG Jian-long Laboratory of Environmental Technology Institute of Nuclear and New Energy Tsinghua University Beijing 100084 China

Field studies were conducted to investigate the advanced treatment of the municipal secondary effluent and a subsequent artificial groundwater recharge at Gaobeidian Wastewater Treatment Plant, Beijing. To improve the secondary effluent quality, the combined process of powdered activated carbon adsorption, flocculation and rapid sand filtration was applied, which could remove about 400 dissolved organic carbon （DOC） and 70% adsorbable organic halogens. The results of liquid size exclusion chromatography indicate that in the adsorption unit the removed organic fraction was mainly low molecular weight compounds. The fractions removed by the flocculation unit were polysaccharides and high molecular weight compounds. The retention of water in summer in the open recharge basins resulted in a growth of algae. Consequently, DOC increased in the polysaccharide and high molecular weight humic substances fraction. The majority of the DOC removal during soil passage took place in the unsaturated area. A limited reduction of DOC was observed in the aquifer zone.

关键词： artificial groundwater recharge soil aquifer treatment dissolved organic carbon

Plasma spray coating on interconnector toward promoted solid oxide fuel cells and solid oxide electrolysis cells

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Frontiers in Energy 2024年第3期18卷 390-398页

作者： Junwen CAO yun zheng Wenqiang ZHANG Bo YU Institute of Nuclear and New Energy Technology(INET) Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing 100084China Department of Chemical Engineering University of WaterlooWaterlooOntario N2L 3G1Canada Institute of New Energy Materials and Engineering School of Materials Science and EngineeringFuzhou UniversityFuzhou 350108China

Interconnector is a critical component to construct solid oxide cells (SOCs) stack. Oxidation of metallic interconnectors and Cr poisoning caused by oxidation are important factors that lead to long-term performance degradation of SOCs. Coating on the interconnector surface is an important approach to inhibit the oxidation and Cr migration of the interconnector. Herein, (La0.75Sr0.25)0.95MnO3–δ (LSM) and Mn1.5Co1.5O4 (MCO) are used to fabricate the coatings of interconnector. Two advanced thermal spray technology, atmospheric plasma spraying (APS) and low-pressure plasma spray (LPPS), are adopted for the coating preparation. The electrochemical performance, rising and cooling cycle stability, and Cr diffusion inhibition performance of the coatings are tested and evaluated. The result indicates that MCO can generate more uniform and denser coatings than LSM. In addition, MCO coatings prepared by LPPS shows the best electrochemical performance, rising and cooling cycle stability, and Cr diffusion inhibition. The initial area specific resistance (ASR) is 0.0027 Ω·cm2 at 800 °C. After 4 cooling cycle tests, the ASR increases to 0.0032 Ω·cm2 but lower than other samples. Meanwhile, the relative intense of Cr at the interface of SUS430 with MCO coatings fabricated by LPPS is lower than that of MCO fabricated by APS after 4 rising and cooling cycle operations, showing more favorable Cr diffusion inhibition performance.

关键词： interconnector coating plasma spray electrochemical performance Cr diffusion inhibition solid oxide cells(SOCs)

Research Overview of the Best Versions of A Dream in Red Mansions since the 20th Century

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学术界 2014年第7期 271-275页

作者： zheng yun School of Literature Fujian Normal University Fuzhou Fujian 350007

There are many different versions of A Dream in Red Mansions and some versions are different from the others in content,which has drawn great attention from the academic circle. Since the 20 th century,different scholars have different views upon which is best among the 13 versions of A Dream in Red Mansions. Some believe that the versions that showthe real writing of Cao Xueqin are the best; while others believe that the versions with the vivid description and artistic influence are the best,and there are still others who stick to both the two views. This paper attempts to overviewsuch researches for almost a century,which is undoubtedly meaningful for the further study of A Dream in Red Mansions in the future.

关键词：红楼梦版本综述艺术感染力学术界曹雪芹

Synthesis of Ferrocene-Modified Carbon Nitride Photocatalysts by Surface Amidation Reaction for Phenol Synthesis

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Chinese Journal of Chemistry 2014年第6期32卷 498-506页

作者： Xiangju Ye yun zheng Xinchen Wang State Key Laboratory of Photocatalysis on Energy and Environment College of ChemistryFuzhou UniversityFuzhouFujian 350002China

A polymeric Fc-CO-NH-C_(3)N_(4)(Fc-CN)material was synthesized by amidation reaction of ferrocenecarboxylic acid(Fc-COOH)with NH_(2)groups on the surface of mesoporous graphitic carbon nitride(MCN).The properties of the as-synthesized samples were characterized by X-ray diffraction,Fourier transform infrared spectroscopy,UV-Vis diffuse reflectance spectra,N2 adsorption-desorption isotherm,photoluminescence spectroscopy,transmis-sion electron microscopy,electron paramagnetic resonance,(photo)electrochemical measurement and X-ray photo-electron *** resultant catalysts were investigated as heterogeneous catalysts for the selective oxida-tion of benzene to phenol using H_(2)O_(2)as a green oxidant under visible light *** results reveal that Fc-modified samples can not only extend the visible light absorption,but also accelerate the bulk-to-surface charge transfer and separation via surface dyadic structures,both of which are favorable for phenol production from ben-zene photocatalytic hydroxylation with H_(2)O_(2).Under the optimal conditions,up to 16.9%phenol yield(based on benzene)is obtained by Fc-CN/1.5-5 sample,and the corresponding Fe content is about 0.64 wt%.Furthermore,after the second run,no significant decrease of the activity(in term of TOF)and the selectivity is found in Fc-CN/_(1.0)-5 *** with the experimental results and Fenton-chemistry,a possible photocatalytic reaction mecha-nism on the hydroxylation of benzene to phenol at neutral medium with visible light is proposed.

关键词： carbon nitride ferrocenecarboxylic acid benzene oxidation photocatalysis phenol