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Main controlling factor and mechanism of gas-in-place content of the Lower Cambrian shale from different sedimentary facies in the western Hubei area, South China

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Petroleum Science 2024年第3期21卷 1488-1507页

作者： gang li Xian-Ming Xiao Bo-Wei Cheng Chen-gang Lu Yue Feng Dong-Sheng li School of Energy Resources China University of Geosciences(Beijing)Beijing100083China Frontiers Science Center for Deep-time Digital Earth China University of Geosciences(Beijing)Beijing100083 China

The Lower Cambrian shale gas in the western Hubei area,South China has a great resource prospect,but the gas-in-place(GIP)content in different sedimentary facies varies widely,and the relevant mechanism has been not well *** the present study,two sets of the Lower Cambrian shale samples from the Wells YD4 and YD5 in the western Hubei area,representing the deep-water shelf facies and shallowwater platform facies,respectively,were investigated on the differences of pore types,pore structure and methane adsorption capacity between them,and the main controlling factor and mechanism of their methane adsorption capacities and GIP contents were *** results show that the organic matter(OM)pores in the YD4 shale samples are dominant,while the inorganic mineral(IM)pores in the YD5 shale samples are primary,with underdeveloped OM *** pore specific surface area(SSA)and pore volume(PV)of the YD4 shale samples are mainly from micropores and mesopores,respectively,while those of the YD5 shale samples are mainly from micropores and macropores,*** methane adsorption capacity of the YD4 shale samples is significantly higher than that of the YD5 shale samples,with a maximum absolute adsorption capacity of 3.13 cm^(3)/g and 1.31 cm^(3)/g in average,*** with the shallow-water platform shale,the deep-water shelf shale has a higher TOC content,a better kerogen type and more developed OM pores,which is the main mechanism for its higher adsorption *** GIP content models based on two samples with a similar TOC content selected respectively from the Wells YD4 and YD5 further indicate that the GIP content of the deep-water shelf shale is mainly 34 m^(3)/t within a depth range of 1000—4000 m,with shale gas exploration and development potential,while the shallow-water platform shale has normally a GIP content oflittle shale gas *** the geological and geochemical conditions of shale gas formation a

关键词： Lower Cambrian shale Deep-water shelf facies Shallow-waterplat form facies Pore structure Methane adsorption Gas-in-place content Controlling factor

A Correlation-Based Stochastic Model for Massive MIMO Channel

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China Communications 2024年第1期21卷 175-187页

作者： Yang liu gang li Chengxiang Wang National Mobile Communications Research Laboratory School of Information Science and EngineeringSoutheast UniversityNanjing 211189China School of Internet of Things Engineering Jiangnan UniversityWuxi 214122China Pervasive Communication Research Center Purple Mountain LaboratoriesNanjing 211111China

In this paper,the channel impulse response matrix(CIRM)can be expressed as a sum of couplings between the steering vectors at the base station(BS)and the eigenbases at the mobile station(MS).Nakagami distribution was used to describe the fading of the coupling between the steering vectors and the *** measurements were carried out to evaluate the performance of this proposed ***,the physical implications of this model were illustrated and the capacities are *** addition,the azimuthal power spectrum(APS)of several models was ***,the channel hardening effect was simulated and *** showed that the proposed model provides a better fit to the measured results than the other CBSM,i.e.,Weichselberger ***,the proposed model can provide better tradeoff between accuracy and complexity in channel *** CIRM model can be used for massive MIMO design in the future communication system design.

关键词： CBSM channel capacity channel hardening channel modeling massive MIMO

Revealing Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles in oxygen/fluorine containing environments:A reactive molecular dynamics study meshing together experimental validation

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Defence Technology（防务技术） 2024年第4期34卷 313-327页

作者： gang li Chuande Zhao Qian Yu Fang Yang Jie Chen Institute of Chemical Materials China Academy of Engineering Physics(CAEP)P.O.Box 919-311Mianyang 621900SichuanChina

Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing *** instance,Al-O reaction is the most common pathway to release limited energy while Al-F reaction has received much attentions to enhance Al combustion ***,microscopic understanding of the Al-O/Al-F reaction dynamics remains unsolved,which is fundamentally necessary to further improve Al combustion *** this work,for the first time,Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles(n-Al)in oxygen/fluorine containing environments have been revealed via reactive molecular dynamics(RMD)simulations meshing together combustion *** RMD simulation systems of Al core/O_(2)/HF,n-Al/O_(2)/HF,and n-Al/O_(2)/CF4 with oxygen percentage ranging from 0%to 100%have been *** n-Al combustion in mixed O_(2)/CF_4 environments have been conducted by constant volume combustion *** results show that Al-O reaction exhibits kinetic benefits while Al-F reaction owns thermodynamic benefits for n-Al *** n-Al/O_(2)/HF,Al-O reaction gives faster energy release rate than Al-F reaction(1.1 times).The optimal energy release efficiency can be achieved with suitable oxygen percentage of 10%and 50%for n-Al/O_(2)/HF and n-Al/O_(2)/CF_4,*** combustion experiments,90%of oxygen percentage can optimally enhance the peak pressure,pressurization rate and combustion ***,Al-O reaction prefers to occur on the surface regions while Al-F reaction prefers to proceed in the interior regions of n-Al,confirming the kinetic/thermodynamic benefits of Al-O/Al-F *** synergistic effect of Al-O/Al-F reaction for greatly enhancing n-Al combustion efficiency is demonstrated at atomicscale,which is beneficial for optimizing the combustion performance of metallic fuel.

关键词： Al-O/Al—F reaction Kinetic benefits Thermodynamic benefits Molecular dynamics Combustion

Density-based ship detection in SAR images:Extension to a self-similarity perspective

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Chinese Journal of Aeronautics 2024年第3期37卷 168-180页

作者： Xueqian WANG gang li Zhizhuo JIANG Yu liU You HE Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China

Nonlocal self-similarity is an important property of Synthetic Aperture Radar(SAR)images to characterize the repetitiveness of features embodied by SAR images within nonlocal areas and has been used for enhancement of SAR *** SAR ship detectors often independently handle small sub-images cropped from a large marine SAR image and do not exploit the nonlocal self-similarity *** this paper,we propose a new ship detector from the perspective of nonlocal self-similarity in SAR images to improve the ship detection performance,basically including three stages:prescreening,intra-cue calculation,and inter-cue *** the prescreening stage,we design a new Histogram-based Density(HD)feature to rapidly select candidate sub-images potentially containing ship targets from a large SAR *** the intra-cue calculation stage,target cues within a single candidate sub-image are *** the inter-cue calculation stage,thanks to the nonlocal self-similarity among different candidate sub-images in terms of density features,we innovatively extract a weighted superpixel-HD map to obtain accumulated intracues across all the candidate ***,for each candidate sub-image,we fuse its inter-cue and intra-cue to obtain final detection *** results based on real SAR images show that our newly proposed method provides a better target-to-clutter contrast and ship detection performance than those of other state-of-the-art detection approaches.

关键词： Ship detection Synthetic aperture radar(SAR) Density Self-similarity Histogram

Characterization of geological uncertainties from limited boreholes using copula-based coupled Markov chains for underground construction

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Underground Space 2024年第3期16卷 94-105页

作者： Fan Wang Heng li gang li Zheng-Jun You Elton J.Chen National Center of Technology Innovation for Digital Construction Huazhong University of Science and TechnologyWuhan 430074China Department of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430074China Department of Building and Real Estate The Hong Kong Polytechnic UniversityKowloon 999077Hong KongChina Shanghai Tunnel Engineering Co. Ltd.Shanghai 200032China Wuhan Metro Group Co.Ltd. Wuhan 430070China

This paper proposes an efficient method for quantifying the stratigraphic uncertainties and modeling the geological formations based on *** Markov chains are used to describe the soil transitions along different directions,and the transition probability matrices(TPMs)of the Markov chains are analytically expressed by *** copula expression is efficient since it can represent a large TPM by a few unknown *** to the analytical expression of the TPMs,the likelihood function of the Markov chain model is given in an explicit *** estimation of the TPMs is then re-casted as a multi-objective constrained optimization problem that aims to maximize the likelihoods of two independent Markov chains subject to a set of parameter *** the method which determines the TPMs by counting the number of transitions between soil types,the proposed method is more statistically ***,a random path sampling method is presented to avoid the directional effect problem in *** soil type at a location is inferred from its nearest known neighbors along the cardinal directions.A general form of the conditional probability,based on Pickard’s theorem and Bayes rule,is presented for the soil type *** proposed stratigraphic characterization and simulation method is applied to real borehole data collected from a construction site in Wuhan,*** is illustrated that the proposed method is accurate in prediction and does not show an inclination during simulation.

关键词： Geological stratigraphy Markov chain Transition probability matrix Statistical method Copula

2000 Experience Chinese Culture in the United States──An Interview with Director-General li gang

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China & The World Cultural Exchange 2000年第6期66卷 10-12页

作者： li Shengxian

From the 24th of last August to the 17th of last September, the 2000 Experience Chinese Culture in the United States,a major activity sponsored jointly by the Chinese Ministryof Culture and the Information Office unde... 详细信息

关键词： In li Experience Chinese Culture in the United States An Interview with Director-General li gang

Transition metal clusters with precise numbers of atoms anchored on graphdiyne as multifunctional electrocatalysts for OER/ORR/HER:a computational study

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Rare Metals 2024年第7期43卷 3107-3117页

作者： Xin-Yang liu Jing-Wei liu gang li Jing-Xiang Zhao College of Chemistry and Chemical Engineering Harbin Normal UniversityHarbin 150025China

Subnanometer metal clusters play an increasingly important role in heterogeneous catalysis due to their high catalytic activity and *** this work,by means of the density functional theory(DFT) calculations,the catalytic activities of transition metal clusters with precise numbers of atoms supported on graphdiyne(TM_(1-4)@GDY,TM=V,Cr,Mn,Fe,Co,Ni,Cu,Ru,Rh,Pd,Ir,Pt) were investigated for oxygen evolution reactions(OER),oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER).The computed results reveal that the Pd_(2),Pd_(4) and Pt_(1) anchored graphdiyne can serve as trifunctional catalysts for OER/ORR/HER with the overpotentials of 0.49/0.37/0.06,0.45/0.33/0.12 and 0.37/0.43/0.01 V,respectively,while Pd_(1) and Pt_(2)@graphdiyne can exhibit excellent catalytic performance for water splitting(OER/HER) with the overpotentials of 0.55/0.17 and 0.43/0.03 *** addition,Ni_(1) and Pd_(3) anchored GDY can perform as bifunctional catalysts for metal-air cells(OER/ORR) and fuels cells(ORR/HER) with the overpotentials of 0.34/0.32 and 0.42/0.04 V,***,by precisely controlling the numbers of atoms in clusters,the TM_(1-4) anchored graphdiyne can serve as promising multifunctional electrocatalysts for OER/ORR/HER,which may provide an instructive strategy to design catalysts for the energy conversation and storage devices.

关键词： Density functional theory Graphdiyne Single-cluster catalysts Multifunctional electrocatalysts Overpotential

On uniqueness and existence of conformally compact Einstein metrics with homogeneous conformal infinity. Ⅱ

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Science China Mathematics 2024年

作者： gang li School of Mathematics Shandong University

In this paper,we show that for an Sp（k+1）-invariant metric ■ on S4k+3（k 1） close to the round metric,the conformally compact Einstein （CCE） manifold （M,g） with (S4k+3,[■]) as its conformal infinity is unique up to ***,by the result in li et al.（2017）,g is the Graham-Lee metric (see Graham and Lee （1991）) on the unit ball B1?R4k+*** also give an a priori estimate of the Einstein metric *** a byproduct of the a priori estimates,based on the estimate and Graham-Lee and Lee’s seminal perturbation results(see Graham and Lee （1991） and Lee （2006）),we directly use the continuity method to obtain an existence result of the non-positively curved CCE metric with prescribed conformal infinity (S4k+3,[■]) when the metric■ is Sp（k+1）-*** also generalize the results to the case of conformal infinity (S15,[■]) with■ a Spin（9）-invariant metric in the appendix.

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Study of the blocking mechanism in gravel packing based on CFD-DEM

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Particuology 2024年第7期90卷 164-178页

作者： Fucheng Deng Lei Wen gang li Baitao Fan Ning Gong Shenghong Chen Yangtze University Jingzhou434023China Guangzhou Institute of Energy Conversion Chinese Academy of Sciences510640China CNOOC Research Institute Ltd Beijing100028China Tianjin Branch of CNOOC Ltd Tianjin300459China CNOOC Ener Tech-Drilling&Production Co Tianjin300457China

Gravel packing sand control(GPSC),as the optimization of mechanical sand control technology,is widely used in the deep water completion and sand control of loose sandstone heavy oil reservoirs and highly *** explore the blocking mechanism of GPSC,the influence of its structural parameters on the blocking of GPSC is *** paper establishes a particle element model based on computational fluid dynamics-discrete element method coupling using the discrete element method and establishes a fluid flow model combined with computational fluid dynamics to realize their full coupling *** sand control experiments were carried out using a micro visual sand control simulation device to verify the blocking *** blocking mechanism is analyzed from the microscopic point of view,and then,the influence of sand control structure parameters on the blocking in GPSC design is *** results show the following:(1)the blocking process of GPSC can be divided into three stages:an initial stage,sand accumulation stage,and equilibrium stage.(2)There are two main types of gravel packing *** first type of blocking is blocking on the surface of the gravel *** particles on the surface of gravel layer mainly exist in the form of large particle size blocking gravel pores and sand particles bridging each *** second type of blockage is the blockage inside the gravel *** particles mainly exist in the form of internal mud cakes and adsorption on gravels inside the gravel layer.(3)To ensure the sand control performance of the gravel layer,the gravel layer thickness is designed between 23 and 28 *** displacement or pressure of the on-site packing pump should be increased to ensure that the gravel layer packing solidity ranges between 59%and 62%.In the design of GPSC,it should be ensured that the median particle size of gravel is 5–6 times the median particle size of *** study provides an effective technical reference for the

关键词： CFD-DEM Blocking the process Blocking mechanism Structural parameter