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A mesoscale model based on Monte-Carlo method for concrete fracture behavior study

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Science China(Technological Sciences) 2012年第12期55卷 3278-3284页

作者： ZHANG NaiLong guo xiaoming ZHU BiBo guo Li Department of Engineering Mechanics School of Civil EngineeringSoutheast UniversityNanjing 210096China Jiangsu Key Laboratory of Engineering Mechanics Southeast UniversityNanjing 210096China Daya Bay Nuclear Power Operations and Management Company Shenzhen 518110China

An aggregate generation and packing algorithm based on Monte-Carlo method is developed to express the aggregate random distribution in cement concrete. A mesoscale model is proposed on the basis of the algorithm. In this model, the concrete con- sists of three parts, namely coarse aggregate, cement matrix and the interracial transition zone （ITZ） between them. To verify the proposed model, a three-point bending beam test was performed and a series of two-dimensional mesoscale concrete mod- els were generated for crack behavior investigation. The results indicate that the numerical model proposed in this study is helpful in modeling crack behavior of concrete, and that treating concrete as heterogeneous material is very important in frac- ture modeling.

关键词： cement concrete fracture Monte-Carlo method aggregate generation and packing algorithm mesoscale models

A new depth-integrated non-hydrostatic model for free surface flows

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Science China(Technological Sciences) 2013年第4期56卷 824-830页

作者： guo xiaoming KANG Ling JIANG TieBing School of Hydropower and Information Engineering Huazhong University of Science and Technology

A new depth-integrated model deploying a non-hydrostatic pressure distribution is *** the pressure divided into hydrostatic and dynamic components,the horizontal momentum equations were obtained by integrating the Navier-Stokes equations from the bottom to the free *** vertical momentum equation,in which the convective and viscosity terms were omitted,was approximated by the Keller-box *** model has two ***,the dynamic pressure gradient terms were discretized semi-implicitly and the other terms were in explicit ***,the velocities expressed as the unknown dynamic pressure were substituted into the continuity equation,resulting in a five-diagonal symmetric matrix linear system that was solved by the conjugate gradient *** model was validated with the propagation of a solitary wave and sinusoidal wave,indicating that it can predict free surface flows well.

关键词： depth-integrated free surface non-hydrostatic pressure waves

Isotopic characteristics and source analysis of atmospheric ammonia during agricultural periods in the Xichuan area of the Danjiangkou Reservoir

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Journal of Environmental Sciences 2024年第2期136卷 460-469页

作者： Xiaoshu Chen Tongqian Zhao Chunyan Xiao xiaoming guo Feihong Chen Institute of Resources and Environment Henan Polytechnic UniversityJiaozuo 454000China

Nitrogen deposition is an important means of exogenous nitrogen input in reservoir *** activities around the reservoir lead to a sharp increase in the concentration of ammonia in the atmosphere,which poses a threat to the reservoir water *** the contribution of agricultural ammonia release to atmospheric NH_(x)(gaseous NH_(3)and particulate NH_(4)^(+)),in the reservoir area can provide a theoretical foundation for local reactive nitrogen *** collected atmospheric NH_(3)and NH_(4)^(+)samples during the agricultural periods and analyzed the isotopic characteristics of atmospheric NH_(x)and the contribution rates of different ammonia sources in the Xichuan area of the Danjiangkou *** results showed that the initialδ~(15)N values of NH_(3)(-30.0‰to–7.2‰)and particulate NH_(4)^(+)(–33‰to+4.9‰for finer and coarser particles,respectively)are different,and their contribution ratios from dissimilar ammonia sources are also different,among which NH_(4)^(+)is more susceptible to meteorological ***,since the atmospheric NH_(x)in the Xichuan area is mainly gaseous NH_(3),the final sources of atmospheric ammonia nitrogen source depend on gaseous NH_(3).Agricultural sources(59%-74%)were the main NH_(3)sources in this *** them,the fertilizer use emission was dominant;it had the highest contribution rate in summer during the agricultural period and a more prominent impact in areas with less human *** regulation of the application of high-ammonia releasing fertilizer,especially during the agricultural period in summer,is an effective way to reduce the threat of atmospheric ammonia to water health.

关键词： Danjiangkou reservoir Atmospheric ammonia nitrogen Isotope Ammonia source analysis Agricultural sources

Effect of copper precursors on CO oxidation catalyzed by CuO-CeO_(2) prepared by solvothermal method

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Journal of Rare Earths 2023年第12期41卷 1953-1962,I0005页

作者： Wen Jin Yanmin Liu Jun Yu xiaoming guo Dongsen Mao School of Chemical and Environmental Engineering Shanghai Institute of TechnologyShanghai201418China

In this paper,the CuO-CeO_(2) catalyst was prepared by a direct solvothermal *** effects of different copper salt precursors(copper nitrate,copper acetate,copper sulfate) on the catalytic performa nce of the prepared catalyst fo r CO oxidation were *** physical and chemical properties of the prepared catalysts were characterized by X-ray diffraction(XRD),Raman spectroscopy,N_(2)physical adsorption,inductively coupled plasma-atomic emission spectrometry(ICP-AES),X-ray photoelectron spectroscopy(XPS),temperature-programmed desorption analysis of CO(CO-TPD),in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs),and temperature-programmed reduction with H_(2)(H_(2)-TPR).The results show that the CuO-CeO_(2)catalyst prepared with copper acetate as precursor(CC-A) exhibits the best catalytic activity for CO oxidation at low temperatures,with T50and T90values of 62 and 78℃ respectively,which is mainly attributed to its large specific surface area,pore volume,CO adsorption capacity,and large amount and strong reactivity of surface ***,the CuO-CeO_(2) catalyst prepared with copper nitrate as precursor(CC-N) displays better stability and resistance to water or CO_(2) poisoning than CC-A.

关键词： Cuo-CeO_(2) Solvothermal method Copper precursor CO oxidation Rare earths

THE PRINCIPLE OF PROPORTIONALITY:SUMMARY AND CONSENSUS IN THE 6TH INTERNATIONAL CONFERENCE ON HUMAN RIGHTS PROTECTION UNDER PANDEMIC PREVENTION AND CONTROL,BEIJING(CHINA)2020

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Frontiers of Law in China-Selected Publications from Chinese Universities 2021年第1期16卷 122-141页

作者： guo xiaoming Law and Development McGill Faculty of LawMontrealCanada Human Rights Center Renmin University of ChinaBeijing 100872China

Against the backdrop of the COVID-19 pandemic and China’s regularized pandemic prevention and control,leading legal scholars from China,North America,and Eurasia participated in The 6th International Conference on Human Rights Protection under Pandemic Prevention and *** engaged in fruitful discussions on the normative necessity and practical relevance of the principle of proportionality in justifying their current governments’anti-pandemic *** on pandemic-related human rights conditions and rule of law challenges in global contexts,this article summarizes the participating scholars’speeches through the integrated lens of human rights and the jurisprudence of health law in the COVID-19 containment *** can be divided into six topical dimensions,involving normative utility,governance logic,reasonable limits,constitutional criteria,viable approaches,and post-pandemic challenges with respect to the principle of *** provide a more policy-relevant and theoretically sound framework for a community of common health for mankind,this article succinctly concludes with a series of overlapping consensus on the application of the principle of proportionality in the fight against the *** consensus,tentatively named the“Renmin Human Rights Consensus,”builds on five interrelated elements and generates five human rights assertions and a series of specific principles of health law.

关键词： anti-pandemic measures COVID-19 containment phase community of common health for mankind proportionality analysis human rights jurisprudence Renmin Human Rights Consensus

Low-temperature NH_(3)-SCR of NO_(x) over MnCeO_(x)/TiO_(2) catalyst:Enhanced activity and SO_(2) tolerance by modifying TiO_(2) with Al_(2)O_(3)

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Journal of Rare Earths 2021年第7期39卷 805-816,I0002页

作者： Gang Li Dongsen Mao Mengxi Chao Gehua Li Jun Yu xiaoming guo School of Chemical and Environmental Engineering Shanghai Institute of TechnologyShanghai 201418China

A series of TiO_(2)-Al_(2)O_(3) composites with Al/Ti molar ratios of 0.1,0.2,and 0.4 were synthesized by a coprecipitation method and used as supports to prepare supported MnCeO_(x) catalysts by an impregnation *** physico-chemical properties of the samples were extensively characterized by N_(2) physisorption,X-ray diffraction,Raman spectroscopy,scanning electron micro scopy and energy-dispersive Xray spectroscopy element mapping,X-ray photoelectron spectroscopy,H_(2)-temperature programmed reduction,ammonia temperature programmed desorption,and in-situ diffuse reflectance infrared Fourier transform *** catalytic activity and resistance to water vapor and SO_(2) of the asprepared catalysts for the SCR of NO_(x) with NH_(3) were evaluated at 50-250℃ and GHSV of 80000 mL/(gcat·h).The results reveal that MnCeO_(x)/TiO_(2)-Al_(2)O_(3) exhibits higher activity and better SO_(2) tolerance than MnCeO_(x)/TiO_(2).Combining with the characterization results,the enhanced activity and SO_(2) tolerance of MnCeO_(x)/TiO_(2)-Al_(2)O_(3) can be mainly attributed to higher relative concentrations of Mn4+and chemisorbed oxygen species,stronger reducibility,and larger adsorption capacity for NH_(3) and NO,which originate from the larger specific surface area and pore volume,higher dispersion of Mn and Ce species compared with MnCeO_(x)/TiO_(2).Moreover,in situ DRIFTS was used to investigate the reaction mechanism,and the results indicate that the NH_(3)-SCR reaction over MnCeO_(x)/TiO_(2) and MnCeO_(x)/TiO_(2)-Al_(2)O_(3) takes place by both the E-R and L-H mechanisms.

关键词： Low-temperature NH_(3)-SCR MnCeO_(x)/TiO_(2)catalyst TiO_(2)-Al_(2)O_(3)mixed oxide SO_(2)tolerance Rare earths

Non-Oxidative Aromatization of CH4-C_3H_8 over La-Promoted Zn/HZSM-5 Catalysts

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Journal of Natural Gas Chemistry 2006年第1期15卷 52-57页

作者： Lihe Zheng Dong Xuan Jianjun guo Hui Lou xiaoming Zheng Institute of Catalysis Chemistry Department Zhejiang University Hangzhou 310028 China

The non-oxidative aromatization of mixed CH4 with C3H8 over La-promoted Zn/HZSM-5 catalysts was studied in a fixed-bed reactor at 823 K with space velocity 600 h^-1 and CH4/C3H8 （mol ratio）=5：l. The propane conversion and the aromatic selectivities were up to 99% and 60% over the catalyst respectively, while methane conversion had an induction period with the highest conversion of 30%. The structure and surface acidity of the catalysts were characterized by XRD, NH3-TPD and TG-DTA. The influences of reaction and regenerative conditions on the activity and selectivity were also investigated.

关键词： aromatization methane propane regeneration La Zn HZSM-5

Free Boundary Problem of Non-steady State Seepage Flow

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Communications in Nonlinear Science and Numerical Simulation 1999年第1期4卷 43-47页

作者： xiaoming guo Ying SUN and Yinghe SHE (Departmant of Engineering Mechanics, Southeast University, Naming Z10096,China) E-mail: xmguo@*** Departmant of Engineering Mechanics Southeast University Nanjing 210096 China

Along with the vigorous developing construction, the number of various underground engineerings is greatly increasing. Such as: the foundations of dams and high- rise multistoried houses, subways and tunnels, water and oil wells etc., where the close attention is always payed to the seepage behaviour in the media around the structures. The Variational inequality formulation and its FEM solution for the free boundary problem of 2D steady state seepage flow was given by the *** this paper a further investigation is made on the non-steady state seepage problem, taken the seepage flow of wells as an example. The presented approach-Variational inequality and its FEM solution- is also very beneficial to the non-steady state problems, where the transient free boundary can also be defined directly without conventional iterations.

关键词： seepage non-steady state, variational inequality

Research progress on bulk nanobubbles

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Particuology 2022年第1期20卷 99-106页

作者： Le Sun Fenghua Zhang xiaoming guo Zhengming Qiao Yi Zhu Nuo Jina Yan Cui Weimin Yang College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China Preparation Office of Zhangzhou Base of National Marine Technology Center Xiamen 361007China

There are still fundamental problems lying in the basic research of bulk *** the bulk nanobubbles reported in the literature nano scale bubbles or contaminants in fact?At present,there is not yet sufficient experimental evidence to show that the bulk nanoparticles are only gas bubbles but not other nano scale *** they are indeed nanobubbles,what causes the bulk nanobubbles observed in the literature to be much more stable than being predicted by the Epstein-Plesset theory?This paper firstly discusses the contradiction between the traditional theory prediction and the observed lifetime of the bulk nanobubbles,and then discusses whether the so-called nanobubbles are gas *** review the existing typical models,and the influence of different conditions on the stability of bulk nanobubbles,for paving the road to a clear understanding of the stability mechanism of bulk *** addition,the representative production methods and characterization methods of bulk nanobubbles are discussed in order to offer some guidance to their wide range of commercial applications.

关键词： Bulk nanobubbles Nano scale contaminants Typical model Stability mechanism