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Impact of effective stress on permeability for carbonate fractured-vuggy rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 942-960页

作者： Ke Sun Huiqing Liu Juliana y.leung Jing Wang yabin Feng Renjie Liu Zhijiang Kang yun Zhang State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China School of Mining&Petroleum Engineering University of AlbertaEdmontonT6G 1H9Canada SINOPEC Petroleum Exploration and Production Research Institute Beijing100083China

To gain insight into the flow mechanisms and stress sensitivity for fractured-vuggy reservoirs,several core models with different structural characteristics were designed and fabricated to investigate the impact of effective stress on permeability for carbonate fractured-vuggy rocks(CFvR).It shows that the permeability performance curves under different pore and confining pressures(*** stress conditions)for the fractured core models and the vuggy core models have similar change *** ranges of permeability variation are significantly wider at high pore pressures,indicating that permeability reduction is the most significant during the early stage of development for fractured-vuggy *** each obtained effective stress coefficient for permeability(ESCP)varies with the changes in confining pressure and pore pressure,the effective stresses for permeability of four representative CFvR show obvious nonlinear characteristics,and the variation ranges of ESCP are all between 0 and ***,a comprehensive ESCP mathematical model considering triple media,including matrix pores,fractures,and dissolved vugs,was *** is proved theoretically that the ESCP of CFvR generally varies between 0 and ***,the regression results showed that the power model ranked highest among the four empirical models mainly applied in stress sensitivity characterization,followed by the logarithmic model,exponential model,and binomial *** concept of“permeability decline rate”was introduced to better evaluate the stress sensitivity performance for CFvR,in which the one-fracture rock is the strongest,followed by the fracture-vug rock and two-horizontalfracture rock;the through-hole rock is the *** general,this study provides a theoretical basis to guide the design of development and adjustment programs for carbonate fractured-vuggy reservoirs.

关键词： Effective stress Permeability Carbonate fractured-vuggy rocks Structure characteristics Stress sensitivity

A Simple Embedding Method for the Laplace-Beltrami Eigenvalue Problem onImplicit Surfaces

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Communications on Applied Mathematics and Computation 2024年第2期6卷 1189-1216页

作者： young Kyu Lee Shingyu leung Department of Mathematics The Hong Kong University of Science and TechnologyClear Water BayHong KongChina

We propose a simple embedding method for computing the eigenvalues and eigenfunctions of the Laplace-Beltrami operator on implicit *** approach follows an embedding approach for solving the surface eikonal *** replace the differential operator on the interface with a typical Cartesian differential operator in the surface *** proposed algorithm is easy to implement and *** will give some two-and three-dimensional numerical examples to demonstrate the effectiveness of our proposed approach.

关键词： Laplace-Beltrami operator Level set method Implicit representation Eigenvalues Numerical PDEs

Deep bed filtration model for cake filtration and erosion

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 355-372页

作者： L.I.KUZMINA y.v.OSIPOv A.R.PESTEREv Department of Applied Mathematics HSE UniversityMoscow 101000Russia Department of Computer Science and Applied Mathematics Moscow State University of Civil EngineeringMoscow 129337Russia

Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtration throughout the entire porous medium, are studied by different models. A unified approach for the transport and deposition of particles based on the deep bed filtration model is proposed. A variable suspension flow rate, proportional to the number of free pores at the inlet of the porous medium, is considered. To model cake filtration, this flow rate is introduced into the mass balance equation of deep bed filtration. For the cake filtration without deposit erosion,the suspension flow rate decreases to zero, and the suspension does not penetrate deep into the porous medium. In the case of the cake filtration with erosion, the suspension flow rate is nonzero, and the deposit is distributed throughout the entire porous medium. An exact solution is obtained for a constant filtration function. The method of characteristics is used to construct the asymptotics of the concentration front of suspended and retained particles for a filtration function in a general form. Explicit formulae are obtained for a linear filtration function. The properties of these solutions are studied in detail.

关键词： deep bed filtration cake filtration porous medium particle deposition and erosion analytical solution concentration front

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Changes of tropical cyclone size in three oceanic basins of the northern hemisphere from 2001 to 2021

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Frontiers of Earth Science 2024年第2期18卷 312-323页

作者： Banglin ZHANG Jeremy Cheuk-Hin leung Shengyuan LIU Jianjun XU Guangzhou Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction CMAGuangzhou 510640China College of Atmospheric Science Lanzhou UniversityLanzhou 730020China College of Ocean and Meteorology Guangdong Ocean UniversityZhanjiang 524088China CMA-GDOU Joint Laboratory for Marine Meteorology&South China Sea Institute of Marine Meteorology Guangdong Ocean UniversityZhanjiang 524088China

In this study the changes of tropical cyclone(TC)size from 2001 to 2021 are analyzed based on linear and quadratic curve fittings of the National Hurricane Center(NHC)/Joint Typhoon Warning Center(JTWC)best track data,based on the radius of maximum wind(RMW)and the average radius of 34-kt wind(AR34),in three oceanic basins of the North Atlantic(NATL),the Western North Pacific(WPAC)and the Eastern North Pacific(EPAC).The computations are done separately for two categories of tropical cyclones:tropical storms(TS)and hurricanes(HT).Size changes of landfalling and non-landfalling TCs are also *** show that there is a great inter-basin variability among the changes in TC *** conclusions include:1)overall,the inner cores of TSs have become larger in all three basins,with the increasing tendencies being significant in the NATL and WAPC,while those of HTs mostly get smaller or remain similar;2)meanwhile,comparatively large inter-basin differences are observed for the TC outer core sizes,and the sizes of landfalling TCs;3)particularly,a significant decrease in landfalling HT outer core size is observed over the EPAC;4)in contrast,significant increases in landfalling TS inner core size are found over the NATL and *** presented analysis results could benefit future research about TC forecasts,storm surge studies,and the cyclone climate and its changes.

关键词： tropical cyclone storm size frequency intensity duration

Translating bacteriophage-derived depolymerases into antibacterial therapeutics:Challenges and prospects

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Acta Pharmaceutica Sinica B 2024年第1期14卷 155-169页

作者： Honglan Wang yannan Liu Changqing Bai Sharon Shui yee leung School of Pharmacy the Chinese University of Hong KongHong Kong SARChina Emergency Medicine Clinical Research Center Beijing Chao-Yang HospitalCapital Medical UniversityBeijing 100020China Department of Respiratory Shenzhen University General HospitalShenzhen University Clinical Medical AcademyGuangdong 518055China

Predatory bacteriophages have evolved a vast array of depolymerases for bacteria capture and *** depolymerases are enzymes responsible for degrading diverse bacterial surface *** are exploited as antibiofilm agents and antimicrobial adjuvants while rarely inducing bacterial resistance,making them an invaluable asset in the era of antibiotic *** depolymerases have been investigated preclinically,with evidence indicating that depolymerases with appropriate dose regimens can safely and effectively combat different multidrug-resistant pathogens in animal infection ***,some formulation approaches have been developed for improved stability and activity of ***,depolymerase formulation is limited to liquid dosage form and remains in its infancy,posing a significant hurdle to their clinical translation,compounded by challenges in their applicability and *** development must address these obstacles for clinical ***,after unravelling the history,diversity,and therapeutic use of depolymerases,we summarized the preclinical efficacy and existing formulation findings of recombinant ***,the challenges and perspectives of depolymerases as therapeutics for humans were assessed to provide insights for their further development.

关键词： Phage-derived polysaccharide depolymerases Bacteriophage proteins Bacterial capsules Polysaccharide capsules Antibiotic resistance Biofilms Antibacterial therapy Antimicrobial adjuvants Combination treatment

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Spatiotemporal variations of sand hydraulic conductivity by microbial application methods

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 268-278页

作者： viroon Kamchoom Thiti Khattiwong Treesukon Treebupachatsakul Suraparb Keawsawasvong Anthony Kwan leung Excellent Centre for Green and Sustainable Infrastructure Department of Civil EngineeringSchool of EngineeringKing Mongkut’s Institute of Technology Ladkrabang(KMITL)Bangkok10520Thailand Department of Biomedical Engineering School of EngineeringKing Mongkut’s Institute of Technology Ladkrabang(KMITL)Bangkok10520Thailand Department of Civil Engineering Thammasat School of EngineeringThammasat UniversityPrathumthani10200Thailand Department of Civil and Environmental Engineering The Hong Kong University of Science and Technology(HKUST)Hong KongChina

The spatiotemporal distributions of microbes in soil by different methods could affect the efficacy of the microbes to reduce the soil hydraulic *** this study,the specimens of bio-mediated sands were prepared using three different methods,***,mixing,and pouring a given microbial so-lution onto compacted sand *** hydraulic conductivity was measured by constant-head tests,while any soil microstructural changes due to addition of the microbes were observed by scan-ning electron microscope(SEM)and mercury intrusion porosimetry(MIP)*** amount of dextran concentration produced by microbes in each type of specimen was quantified by a *** show that dextran production increased exponentially after 5-7 d of microbial settling with the supply of culture *** injection and mixing methods resulted in a similar amount and uniform dis-tribution of dextran in the *** pouring method,however,produced a nonuniform distri-bution,with a higher concentration near the specimen *** the supply of culture medium discontinued,the dextran content near the surface produced by the pouring method decreased dramatically due to high competition for nutrients with foreign *** dextran concentration was negatively and correlated with hydraulic conductivity of bio-mediated soils exponentially,due to the clogging of large soil pores by *** hydraulic conductivity of the injection and mixing cases did not change significantly when the supply of culture medium was absent.

关键词： Bio-mediated soil Dextran Hydraulic conductivity Leuconostoc mesenteroides Microbial application Microstructure

Modelling smear effect of vertical drains using a diameter reduction method

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 279-290页

作者： Zhichao Shen Siau Chen Chian Siew Ann Tan Chun Fai leung School of Marine Science and Engineering South China University of TechnologyGuangzhouChina Department of Civil and Environmental Engineering National University of SingaporeSingapore

vertical drains are used to accelerate consolidation of clays in ground improvement *** zones exist around these drains,where permeability is reduced due to soil disturbance caused by the installation *** solution is widely used in practice to consider the effects of drain discharge capacity and smear on the consolidation *** this study,a computationally efficient diameter reduction method(DRM)obtained from the Hansbo solution is proposed to consider the smear effect without the need to model the smear zone *** by analytical and numerical results,a diameter reduction factor is analytically derived to reduce the diameter of the drain,while achieving similar solutions of pore pressure dissipation profile as the classical full model of the smear zone and *** the DRM,the excess pore pressure u obtained from the reduced drain in the original un-disturbed soil zone is accurate enough for practical applications in numerical *** performance of DRM is independent of soil material *** also show equally accurate performance of DRM under conditions of multi-layered soils and coupled radial-vertical groundwater flow.

关键词： Consolidation vertical drain Smear effect Pore pressure Soil improvement

RepDNet:A re-parameterization despeckling network for autonomous underwater side-scan sonar imaging with prior-knowledge customized convolution

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Defence Technology（防务技术） 2024年第5期35卷 259-274页

作者： Zhuoyi Li Zhisen Wang Deshan Chen Tsz leung yip Angelo P.Teixeira Department of Logistics and Maritime Studies The Hong Kong Polytechnic UniversityChina State Key Laboratory of Maritime Technology and Safety Wuhan University of TechnologyChina School of Transportation and Logistics Engineering Wuhan University of TechnologyChina National Engineering Research Center for Water Transport Safety Wuhan University of TechnologyChina Centre for Marine Technology and Ocean Engineering(CENTEC) Instituto Superior TecnicoUniversidade de LisboaPortugal

Side-scan sonar(SSS)is now a prevalent instrument for large-scale seafloor topography measurements,deployable on an autonomous underwater vehicle(AUv)to execute fully automated underwater acoustic scanning imaging along a predetermined ***,SSS images often suffer from speckle noise caused by mutual interference between echoes,and limited AUv computational resources further hinder noise *** approaches for SSS image processing and speckle noise reduction rely heavily on complex network structures and fail to combine the benefits of deep learning and domain *** address the problem,Rep DNet,a novel and effective despeckling convolutional neural network is *** DNet introduces two re-parameterized blocks:the Pixel Smoothing Block(PSB)and Edge Enhancement Block(EEB),preserving edge information while attenuating speckle *** training,PSB and EEB manifest as double-layered multi-branch structures,integrating first-order and secondorder derivatives and smoothing *** inference,the branches are re-parameterized into a 3×3 convolution,enabling efficient inference without sacrificing *** DNet comprises three computational operations:3×3 convolution,element-wise summation and Rectified Linear Unit *** on benchmark datasets,a real SSS dataset and Data collected at Lake Mulan aestablish Rep DNet as a well-balanced network,meeting the AUv computational constraints in terms of performance and latency.

关键词： Side-scan sonar Sonar image despeckling Domain knowledge Re-parameterization

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Centrifuge study on behavior of raft foundation after tunnelling in soft clay

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Underground Space 2024年第4期17卷 161-169页

作者： Jian yu Jiaming Liu Chun Fai leung Maosong Huang Qi Wen Jorgin Tan Department of Geotechnical Engineering Key Laboratory of Geotechnical and Underground Engineering of Ministry of EducationTongji UniversityShanghai 200092China Centre for Offshore Research and Engineering Department of Civil and Environmental EngineeringNational University of Singapore119077Singapore Land Transport Authority 219428Singapore

Ground losses due to tunneling would induce settlement of nearby raft *** study the change in behavior of the raft foundations over time due to tunnel excavation in soft clay,a series of centrifuge model tests were *** results reveal that the raft stiffness has a significant influence on the development of the gap between the raft and the *** width of the gap beneath the flexible foundation would increase over time,leading to a further increase in tensile strain after excavation,whereas the gap for raft foundations with a large stiffness would reduce with time,causing a gradual decrease in tensile *** modification factor(MF)design approach is also evaluated with the test results and demonstrates that the MF design approach would underestimate the tensile strain of the flexible raft and provide a relatively conservative prediction for larger stiffnesses.

关键词： Tunnelling Raft Clay Deflection ratio Centrifuge test