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Investigation of influence factors on CO_(2) flowback characteristics and optimization of flowback parameters during CO_(2) dry fracturing in tight gas reservoirs

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Petroleum Science 2023年第6期20卷 3553-3566页

作者： xiao-Mei Zhou Lei Li Yong-Quan Sun Ran Liu Ying-chun Guo Yong-mao Hao Yu-Liang Su National Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Shengli Oil Field Dongsheng Jinggong Petroleum Development(GROUP)Stock Co. Ltd.Dongying257000ShandongChina Exploration and Development Research Institute of Shengli Oilfield Company SinopecDongying257000ShandongChina

CO_(2) dry fracturing is a promising alternative method to water fracturing in tight gas reservoirs,especially in water-scarce areas such as the Loess *** CO_(2) flowback efficiency is a critical factor that affects the final gas production ***,there have been few studies focusing on the flowback characteristics after CO_(2) dry *** this study,an extensive core-to-field scale study was conducted to investigate CO_(2) flowback characteristics and CH_(4) production ***,to investigate the impact of core properties and production conditions on CO_(2) flowback,a series of laboratory experiments at the core scale were ***,the key factors affecting the flowback were analyzed using the grey correlation method based on field ***,taking the construction parameters of Well S60 as an example,a dual-permeability model was used to characterize the different seepage fields in the matrix and fracture for tight gas *** production parameters after CO_(2) dry fracturing were then *** results demonstrate that CO_(2) dry fracturing is more effective than slickwater fracturing,with a 9.2%increase in CH_(4) *** increase in core permeability plays a positive role in improving CH_(4) production and CO_(2) *** soaking process is mainly affected by CO_(2) diffusion,and the soaking time should be controlled within 12 *** the flowback pressure gradient results in a significant increase in both CH_(4) recovery and CO_(2) flowback ***,an increase in CO_(2) injection is not conducive to CH_(4) production and CO_(2) *** on the experimental and field data,the important factors affecting flowback and production were comprehensively and effectively *** results show that permeability is the most important factor,followed by porosity and effective *** flowback efficiency and the influence of proppant reflux,the injection volume should

关键词： CO_(2)fracturing Tight gas reservoir Fracturing fluid flowback Parameter optimization

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Generation of Maximally Entangled States for Many Two-Level Atoms in a Thermal Cavity

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Communications in Theoretical Physics 2007年第3期47卷 557-560页

作者： JIANG chun-Lei FANG mao-Fa College of Physics and Information Science Hunan Normal University Changsha 410081 China

We propose a scheme for generating maximally entangled states for two or more two-level atoms in a thermal cavity. The cavity frequency is large-detuned from the atomic transition frequency, so the Hamiltonian can be expressed as an effective form. The photon-number-dependent parts in the effective Hamiltonian are cancelled with the assistance of a strong classical field, thus the scheme is insensitive to both the cavity decay and the thermal field. The scheme can be used to generate multi-atom Bell-state and Greenberger-Horne-Zeiliner （GHZ） state.

关键词： entanglement GHZ state large-detune

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Hierarchically 1D CdS decorated on 2D perovskite-type La_(2)Ti_(2)O_(7) nanosheet hybrids with enhanced photocatalytic performance

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Rare Metals 2021年第5期40卷 1067-1076页

作者： Liang mao xiao-Yan Cai Ming-Shan Zhu School of Materials Science and Physics China University of Mining and TechnologyXuzhou 221116China Jiangsu Province Engineering Laboratory of High Efficient Energy Storage Technology and Equipment China University of Mining and TechnologyXuzhou 221116China School of Environment Jinan UniversityGuangzhou 511443China

In this paper,a heterojunction of hierarchically one-dimensional(1D)cadmium sulfide(CdS)nanowires decorated on the two-dimensional(2D) La_(2)Ti_(2)O_(7) (LTO)has been fabricated by a simple two-step hydrothermal *** structure,morphology and surface chemical composition of CdS/LTO were studied by a variety of characterizations,in which the X-ray photoelectron spectroscopy(XPS)results showed a strong interaction between CdS and LTO through S-O *** typeⅡband alignment of CdS/LTO for favorable electron transfer from CdS to LTO and hole transfer from LTO to CdS was clarified by ultraviolet-visible(UV-Vis)diffuse reflectance spectroscopy and Mott-Schottky(M-S)plot *** the absence of any co-catalyst,H2 production from water splitting and Rhodamine B(RhB)decomposition in aqueous solution were carried out to evaluate the photocatalytic activities,showing that the photocatalytic performance of CdS/LTO was superior to that of pure LTO and CdS under visible light and simulated *** optimal CdS content in the CdS/LTO system was determined to be 7.5 wt%.The present results show an effective pathway to design a 1D/2D heterojunction photocatalyst in the face of overwhelming problems of energy crisis and environmental pollution.

关键词： Cadmium sulfide Lanthanum titanium oxide Heterojunction H_(2)production Dyes degradation

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Thermal insulation performance of 7YSZ TBCs adjusted via Al modification

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Rare Metals 2023年第3期42卷 994-1004页

作者： Jun-Gui Zhang Xi Tan Xiu-Juan Fan Jie mao chun-Ming Deng Min Liu Ke-Song Zhou xiao-Feng Zhang Institute of New Materials The Key Lab of Guangdong for Modern SurfaceEngineering TechnologyGuangdong Academy of SciencesNational Engineering Laboratory of Modern Materials Surface Engineering TechnologyGuangzhou 510651China

ZrO_(2)-7 wt% Y_(2)O_(3)(7YSZ)thermal barrier coatings(TBCs)with three different structures were prepared by atmospheric plasma spraying(APS),electron beam physical vapor deposition(EB-PVD)and plasma spray-physical vapor deposition(PS-PVD).Al films were deposited onto the top 7YSZ TBCs by magnetron sputtering,and the Al-deposited 7YSZ TBCs were subjected to vacuum heat *** effects of Al modification on the thermal insulation properties of 7YSZ TBCs were *** results showed that Al modification could significantly improve the thermal insulation of 7YSZ TBCs at 1000℃.Moreover,the maximum improvement of thermal insulation for PS-PVD 7YSZ TBCs was approximately 100℃,but the improvement decreased with increasing *** is mainly because with increasing temperature,the rate of radiation heat transfer increases,and the effects of convection heat transfer and thermal conductivity on thermal insulation are *** the same temperature,Al modification of PS-PVD7YSZ TBCs provides better temperature insulation than those of APS 7YSZ TBCs and EB-PVD 7YSZ TBCs because of its wider and deeper inter-columnar *** the temperature was 12000C,Al modification still caused a good insulation effect in PS-PVD 7YSZ TBCs;the improvement was approximately 50℃,but in APS and EB-PVD 7YSZ TBCs,the insulation effect disappeared.

关键词： Al modification Thermal barrier coatings(TBCs) Thermal insulation Inter-columnar gap

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6AZO-CONTAINING SELF-ASSEMBLY ULTRA-THIN FILMS AND THEIR PHOTOVOLTAIC PROPERTIES

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Chinese Journal of Polymer Science 2005年第1期23卷 23-27页

作者： mao-fengZhang Qiao-hongYao chun-huiHuang Wei-xiaoCao CollegeofChemistryandMolecularEngineering PekingUniversityBeijing100871China StateKeyLaboratoryofRareEarthMaterialsChemistryandApplications PekingUniversityBeijing100871China

A kind of azo-containing resin(Azo-R)was synthesized by a simple way through the coupling reaction of 2-nitro-N-methyldiphenylamine-4-diazoresin(NDR)with phenol,and a new covalentely attached multilayer film from Azo-R asH-donor and photosensitive diazoresin,diphenylamine-4-diazoresin(DR)as H-acceptor via H-bonding attraction by self-assembly technique has been *** the decomposition of diazonium group of DR under exposure to UVlight,the H-bonds between the layers of the film convert to covalent bonds and the film becomes very stable toward polarsolvents or electrolyte aqueous *** the UV-irradiated azo-containing films can be used to measure photocurrentin a conventional three-electrode photoelectrochemical cell using KCl as supporting *** was confirmed that theazo-containing multilayer film is responsible for the photocurrent generation.

关键词： Azo-containing resin Self-assembly film Photovoltaic property.

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Precise Asymptotics in Limit Theorems for a Supercritical Branching Process with Immigration in a Random Environment

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Acta Mathematica Sinica,English Series 2024年第8期40卷 1850-1874页

作者： chun mao HUANG Rui ZHANG Zhi Qiang GAO Department of Mathematics Harbin Institute of Technology(Weihai)Weihai 264209P.R.China School of Mathematical Sciences Beijing Normal UniversityBeijing 100875P.R.China

Let(Zn)be a supercritical branching process with immigration in an independent and identically distributed random *** necessary moment conditions,we show the exact convergence rate in the central limit theorem on log Zn and establish the corresponding local limit theorem by using the moments of the natural submartingale and the convergence rates of its *** similar approach and with the help of a change of measure,we also present the so-called integrolocal theorem and integral large deviation theorem to characterize the precise asymptotics of the upper large deviations.

关键词： Branching process with immigration random environment central limit theorem large deviation

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A Physicoempirical Model for Soil Water Simulation in Crop Root Zone

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Pedosphere 2011年第4期21卷 512-521页

作者： SHANG Song-Hao mao xiao-Min State Key Laboratory of Hydroscience and Engineering Department of Hydraulic Engineering Tsinghua University Beijing 100084 (China) Center for Agricultural Water Research in China College of Water Conservancy and Civil Engineering China Agricultural University Beijing 100083 (China)

To predict soil water variation in the crop root zone, a general exponential recession （GER） model was developed to depict the recession process of soil water storage. Incorporating the GER model into the mass balance model for soil water, a GER-based physicoempirical （PE-GER） model was proposed for simulating soil water variation in the crop root zone. The PE-GER model was calibrated and validated with experimental data of winter wheat in North China. Simulation results agreed well with the field experiment results, as well as were consistent with the simulation results from a more thoroughly developed soil water balance model which required more detailed parameters and inputs. Compared with a previously developed simple exponential recession （SER） based physicoempirical （PF^SER） model, PE-GER was more suitable f0r application in a broad range of soil texture, from light soil to heavy soil. Practical application of PE-GER showed that PE-GER could provide a convenient way to simulate and predict the variation of soil water storage in the crop root zone, especially in case of insufficient data for conceptual or hydrodynamic models.

关键词： general exponential recession model irrigation scheduling recession process soil texture

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Effective Thermal Conductivity for 3D Five-Directional Braided Composites Based on Microstructural Analysis

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第1期36卷 128-138页

作者： ZHAO xiao mao Junkui JIANG Hua Key Laboratory of Aerospace Power System College of Energy and Power EngineeringNanjing University of Aeronautics and Astronautics Cummins(China) Investment Co. Ltd. Commercial Aircraft Corporation of China Ltd.

A method for predicting effective thermal conductivities(ETCs) of three-dimensional five-directional(3D5D) braided composites is presented. The effective thermal conductivity prediction method contains a digital image processing technology. Multiple scanning electron microscopy(SEM)images of composites are analyzed to obtain actual microstructural features. These actual microstructural features of 3D5D braided composites are introduced into representative volume element(RVE) modeling. Apart from applying actual microstructural features,compression effects between yarns are considered in the modeling of RVE,making the RVE more realistic. Therefore,the ETC prediction method establishes a representative unit cell model that better reflects the true microstructural characteristics of the 3D5D braided composites. The ETCs are predicted with the finite element method. Then thermal conductivity measurements are carried out for a 3D5D braided composite *** comparing the predicted ETC with the measured thermal conductivity, the whole process of the ETC prediction method is proved to be effective and accurate,where a relative error of only 2.9 % is ***,the effects of microstructural features are investigated,indicating that increasing interior braiding angles and fiber fill factor can lead to higher transverse ETCs. Longitudinal ETCs decrease with increasing interior braiding angles,but increase with increasing fiber fill factor. Finally,the influence of variations of microstructure parameters observed in digital image processing are investigated. To explore the influence of variations in microstructural features on variations in predicted ETCs,the actual probability distributions of microstructural features obtained from the 3D5D braided composite sample are introduced into the ETC investigation. The results show that,compared with the interior braiding angle,variations in the fiber fill factor exhibit more significant effects on variations in ETCs.

关键词： effective thermal conductivity digital image processing variation 3D five-directional braided composites

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Takesaki-Takai Duality Theorem in Hilbert C^＊-Modules

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Acta Mathematica Sinica,English Series 2004年第6期20卷 1079-1088页

作者： mao Zheng GUO xiao Xia ZHANG LMAM Department of Mathematics Peking University Department of Mathematics Yantai University

In this paper,we generalize the Takesaki-Takai duality theorem in Hilbert C~*-modules; that is to say,if (H,V,U) is a Kac-system,where H is a Hilbert space,V is a multiplicative unitary operator on H(?)H and U is a unitary operator on H,and if E is an (?)-compatible Hilbert (?)-module, then E×(?)×(?)K(H),where K(H) is the set of all compact operators on H,and (?) and (?) are Hopf C~*-algebras corresponding to the Kac-system (H,V,U).

关键词： Coaction Crossed product Multiplicative unitary operator Hilbert C~*-module

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A new species of the genus Kurixalus(Anura:Rhacophoridae)from Sichuan Province,southwestern China

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Zoological Research 2022年第1期43卷 90-94页

作者： chun-Peng Guo mao-Jun Zhong Ka Wah Leung xiao-Yi Wang Jun-Hua Hu Chengdu Institute of Biology Chinese Academy of SciencesChengduSichuan 610041China University of Chinese Academy of Sciences Beijing 100049China

Combining morphological and molecular data,we describe a new amphibian species of the genus Kurixalus Ye,Fei,&Dubois,1999 from the Qionglai Mountain within the western margin of the Sichuan Basin in *** qionglaiensis *** be diagnosed based on a combination of the following morphological characters:medium-sized within genus(snout-vent length(SVL)in males 28.9−33.3 mm);tympanum distinct,subequal to half of eye diameter;snout pointed,prominence on tip;iris golden with brown spots;slight nuptial pad on first finger in males;background coloration of dorsal surface brown,lateral body and femoral yellow;white,dark brown edged triangular markings on cheek;chin shaded dark brown;pair of large symmetrical dark patches on chest;belly clouded brown and scattered black spots;toes moderately webbed,formulaⅠ2-2Ⅱ1.5-2.5Ⅲ1.5-2.5Ⅳ2.5-1.5Ⅴ;tibia length slightly shorter than half of SVL,tibiotarsal articulation reaching posterior border of eye;single external vocal sac *** on the 16S rRNA gene,the genetic distance between the new species and its sister taxon ***(Kuramoto&Wang,1987)was 4%.At present,the new species is known only from a single location at an elevation of~600 m in Pingle Town,Qionglai City,Sichuan,southwestern *** location can represent a new northernmost geographical limit of the genus Kurixalus.

关键词： southwestern sized scattered

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