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

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

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Quantitative and qualitative subgenomic RNA profiles of SARS-CoV-2 in respiratory samples: A comparison between Omicron BA.2 and non-VOC-D614G

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Virologica Sinica 2024年第2期39卷 218-227页

作者： Zigui Chen Rita Way yin Ng Grace Lui Lowell Ling Agnes S.y.leung Chit Chow Siaw Shi Boon Wendy C.S.Ho Maggie Haitian Wang Renee Wan yi Chan Albert Martin Li David Shu Cheong Hui Paul Kay Sheung Chan Department of Microbiology Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Medicine and Therapeutics Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Anaesthesia and Intensive Care Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Paediatrics Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Anatomical and Cellular Pathology Faculty of MedicineThe Chinese University of Hong KongHong KongChina Jockey Club School of Public Health and Primary Care Faculty of MedicineThe Chinese University of Hong KongHong KongChina Stanley Ho Centre for Emerging Infectious Diseases Faculty of MedicineThe Chinese University of Hong KongHong KongChina

The SARS-CoV-2 Omicron variants are notorious for their transmissibility,but little is known about their subgenomic RNA(sgRNA)*** study applied RNA-seq to delineate the quantitative and qualitative profiles of canonical sgRNA of 118 respiratory samples collected from patients infected with Omicron BA.2 and compared with 338 patients infected with non-variant of concern(non-VOC)-D614G.A unique characteristic profile depicted by the relative abundance of 9 canonical sgRNAs was reproduced by both BA.2 and non-VOCD614G regardless of host gender,age and presence of ***,such profile was lost in samples with low viral load,suggesting a potential application of sgRNA pattern to indicate viral activity of individual patient at a specific time point.A characteristic qualitative profile of canonical sgRNAs was also reproduced by both BA.2 and *** presence of a full set of canonical sgRNAs carried a coherent correlation with crude viral load(AUC¼0.91,95%CI 0.88–0.94),and sgRNA ORF7b was identified to be the best surrogate marker allowing feasible routine application in characterizing the infection status of individual *** potentials in using sgRNA as a target for vaccine and antiviral development are worth pursuing.

关键词： Coronavirus SARS-CoV-2 Omicron BA.2 Non-VOC-D614G RNA-seq Subgenomic RNA(sgRNA)

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Aluminum-air battery with cotton substrate:Controlling the discharge capacity by electrolyte pre-deposition

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Green Energy & Environment 2023年第3期8卷 757-766页

作者： Wending Pan yifei Wang Holly y.H.Kwok Dennis y.C.leung Department of Mechanical Engineering The University of Hong KongHong KongChina

Conventional Al-air battery has many disadvantages for miniwatt applications,such as the complex water management,bulky electrolyte storage and potential leakage ***,the self-corrosion of Al anode continues even when the electrolyte flow is stopped,leading to great Al *** tackle these issues,an innovative cotton-based aluminum-air battery is developed in this *** of flowing alkaline solution,cotton substrate pre-deposited with solid alkaline is used,together with a small water reservoir to continuously wet the cotton and dissolve the alkaline *** this manner,the battery can be mechanically recharged by replacing the cotton substrate and refilling the water reservoir,while the thick aluminum anode can be reused for tens of times until complete *** cotton substrate shows excellent ability for the storage and transportation of alkaline electrolyte,leading to a high peak power density of 73 mW cm^(-2) and a high specific energy of 930 mW h g^(-1).Moreover,the battery discharge capacity is found to be linear to the loading of pre-deposited alkaline,so that it can be precisely controlled according to the mission profile to avoid Al ***,a two-cell battery pack with common water reservoir is developed,which can provide a voltage of 2.7 V and a power output of 223.8 *** further scaling-up and stacking,this cotton-based Al-air battery system with low cost and high energy density is very promising for recharging miniwatt electronics in the outdoor environment.

关键词： Al-air battery Cotton-based Electrolyte pre-deposition Capacity control Miniwatt electronics

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Mechanistic study of vacuum UV catalytic oxidation for toluene degradation over CeO_(2) nanorods

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Green Energy & Environment 2022年第3期7卷 533-544页

作者： Muyan Wu yingguang Zhang Haibao Huang Dennis y.C.leung Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina School of Environmental Science and Engineering Sun Yat-sen UniversityGuangzhou510275China

The present study specifically investigates vacuum ultraviolet (VUV) catalytic oxidation for toluene degradation over CeO_(2) *** effects of ultraviolet photocatalytic oxidation (UV-PCO) and ozone catalytic oxidation (OZCO) were manifested in the results of toluene removal and COx generation,while the combination of UV-PCO andOZCO (UV-OZCO) did not lead to improvement of *** the processes contribute to ozone decomposition,but no obvious synergetic effects of the different processes can be *** analysis results indicated that more toluene was oxidized into by-products,such as benzyl alcohol and benzaldehyde,by UV-OZCO rather than forming *** hydroxyl radical (·OH) and superoxide radical (·O_(2)^(-)) were found in all the processes of the VUV-PCO-OZCO system(combination of VUV photolysis,UV-PCO,OZCO and UV-OZCO processes).In the UV-OZCO process,the formation of hydroxyl radical was promoted,while that of superoxide radical was impeded,resulting in lower mineralization level of *** mechanistic study of toluene degradation over CeO_(2) nanorods in the VUV-PCO-OZCO system revealed that with the formation of·O_(2)^(-)and·OH,toluene is first oxidized to intermediates,followed by further ring–opening reaction and,finally,degradation into CO_(2) and H_(2)***_(2) nanorods function as both ozonation catalyst and photocatalyst,and the redox pair of Ce^(3+)and Ce^(4+)are interconvertible and can keep a balance.

关键词： toluene catalytic vacuum

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Advances in Atmospheric Sciences 2022年第1期39卷 67-79页

作者： Paxson K.y.CHEUNG Wen ZHOU Dongxiao WANG Marco y.T.leung Guy-Carpenter Asia-Pacific Climate Impact Centre School of Energy and EnvironmentCity University of Hong KongHong KongChina Department of Atmospheric and Oceanic Sciences&Institute of Atmospheric Sciences Fudan UniversityShanghai 200438China School of Marine Sciences Sun Yat-sen UniversityGuangdong 510275China

This study focuses on the temporal variation of dissimilarity in heat content(HC)anomalies in the upper 300 m of ocean(HC300A)in the equatorial Pacific(±10°N)and its response to the El Ni?o-Southern Oscillation(ENSO).The HC300A anomalies are derived from four ocean reanalyses that are commonly used in ENSO studies and are compared using a simple differencing *** dissimilarity in HC300A is found to vary closely with the magnitude of ENSO(regardless of phase),meaning that it tends to be greater during strong ENSO ***,the dissimilarity among ocean reanalyses persists after the event *** effect is more pronounced after strong *** persistence of the dissimilarity after ENSO events is a result of a late maturation of the ENSO signal,its persistence,and the interruption of the signal decay due to follow-up ENSO *** combined effect of these three factors slows down the decay of HC300A in the region and hence results in the slow decay of *** is also found that areas with a significant spread in vertical temperature profiles collocate with the ENSO signal during warm ENSO ***,differences in subsurface process reconstruction are a significant factor in the dissimilarity among ocean reanalyses during warm ENSO events.

关键词： ocean reanalysis ocean heat content intercomparison ENSO equatorial Pacific

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Low-cost and efficient Mn/CeO_(2) catalyst for photocatalytic VOCs degradation via scalable colloidal solution combustion synthesis method

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Journal of Materials Science & Technology 2022年第21期116卷 169-179页

作者： yingguang Zhang Muyan Wu yifei Wang Xiaolong Zhao Dennis y.C.leung Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen 518000China

Colloidal solution combustion synthesis(CSCS)is a simple and easy method for mass-production of crystalline nanomaterials with tunable pore *** this work,mesoporous Mn/CeO_(2) catalysts were fabricated via CSCS method coupled with a dip-coating process and used for photocatalytic oxidation(PCO)of *** vacuum ultraviolet(VUV)irradiation,a high toluene removal efficiency of about 92%was achieved with a toluene reaction rate of about 118μmol/g/h in a continuous flow reactor.A possible degradation pathway was proposed based on the analysis of intermediates by Fourier transform infrared photoluminescence spectra(FTIR)and *** temperature-programmed reduction(H_(2)-TPR),Brunauer-Emmett-Teller(BET)surface areas,photoluminescence spectra(PL)spectra and X-ray photoelectron spectroscopy(XPS)were carried out to analyze physical and chemical properties of the *** with Mn_(x)Ce_(1-x)O_(2) catalysts synthesized by one step CSCS method,Mn/CeO_(2) has a higher photocatalytic activity,which is attributed to the presence of higher contents of Ce^(3+),Mn^(2+)and Mn^(3+)*** presence of higher contents of these species plays a key role in the activity enhancement of toluene oxidation and ozone *** method is facile,efficient and scalable,and it may become a promising industrial application technology for catalyst synthesis in the near future.

关键词： Mesoporous CeO_(2) Manganese modification Scalable synthesis Photocatalysis VOCs abatement

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Extended Impact of Cold Air Invasions in East Asia in Response to a Warm South China Sea and Philippine Sea

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Advances in Atmospheric Sciences 2023年第3期40卷 531-540页

作者： Marco y.-T.leung Dongxiao WANG Wen ZHOU yuntao JIAN School of Marine Sciences Sun Yat-Sen UniversityZhuhai 519082China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China Department of Atmospheric and Oceanic Sciences&Institute of Atmospheric Sciences Fudan UniversityShanghai 200438China Guy Carpenter Asia-Pacific Climate Impact Centre Center for Ocean Research in Hong Kong and Macao(CORE)School of Energy and EnvironmentCity University of Hong KongHong KongChina

During boreal winter,the invasion of cold air can lead to remarkable temperature drops in East Asia which can result in serious socioeconomic ***,we find that the intensity of strong synoptic cold days in the East China Sea and Indochina Peninsula are *** enhanced synoptic cold days in these two regions are attributed to surface warming over the South China Sea and Philippine Sea(SCSPS).The oceanic forcing of the SCSPS on the synoptic cold days in the two regions is verified by numerical *** warming of the SCSPS enhances the baroclinicity,which intensifies meridional wind and cold advection on synoptic *** leads to a more extended region that is subject to the influence of cold invasion.

关键词： ocean warming extra-tropical cyclones baroclinicity temperature whiplash

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An Extreme Drought over South China in 2020/21 Concurrent with an Unprecedented Warm Northwest Pacific and La Niña

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Advances in Atmospheric Sciences 2022年第10期39卷 1637-1649页

作者： Weijie FENG Marco y.-T.leung Dongxiao WANG Wen ZHOU Oscar y.W.ZHANG School of Marine Sciences Sun Yat-Sen UniversityZhuhai 519082China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China Department of Atmospheric and Oceanic Sciences&Institute of Atmospheric Sciences Fudan UniversityShanghai 200433China Guy Carpenter Asia-Pacific Climate Impact Centre School of Energy and EnvironmentCity University of Hong KongHong KongChina

An extreme drought appeared in South China from October 2020 to March *** that time,sea surface temperatures exhibited an unprecedented warm center over the northwest Pacific(NWP)and a cold center over the tropical eastern Pacific(La Niña).This study demonstrates the combined effects of an exceptionally warm NWP and a moderate La Niña are closely linked to the anomalous drought in South *** sea surface temperature anomaly in these two regions induced a steeper horizontal geopotential height gradient over South *** a result,anomalous northeasterly winds prevailed over South China,altering water vapor transport and moisture convergence.A simplified atmospheric general circulation model also verifies the influence of the NWP warm anomaly on South China *** study points out that the sea surface temperature variation in the NWP was important to the occurrence of extreme drought in South China from October 2020 to March 2021.

关键词： drought in South China ENSO northwest Pacific warming

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Solid-state Al-air battery with an ethanol gel electrolyte

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Green Energy & Environment 2023年第4期8卷 1117-1127页

作者： yifei Wang Wending Pan Kee Wah Leong Shijing Luo Xiaolong Zhao Dennis y.C.leung School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhenChina Department of Mechanical Engineering The University of Hong KongHong KongChina

Hydrogel electrolyte is especially suitable for solid-state Al-air batteries targeted for various portable applications, which may, however, lead to continuous Al corrosion during battery standby. To tackle this issue, an ethanol gel electrolyte is developed for Al-air battery for the first time in this work, by using KOH as solute and polyethylene oxide as gelling agent. The ethanol gel is found to effectively inhibit Al corrosion compared with the water gel counterpart, leading to stable Al storage. When assembled into an Al-air battery, the ethanol gel electrolyte achieves a much improved discharge lifetime and specific capacity, which are 5.3 and 4.1 times of the water gel electrolyte at 0.1 mA cm^(-2), *** studying the gel properties, it is found that a lower ethanol purity can improve the battery power output, but at the price of decreased discharge efficiency. On the contrary, a higher polymer concentration will decrease the power output, but can bring extra benefit to the discharge efficiency. As for the gel thickness, a moderate value of 1 mm is preferred to balance the power output and energy efficiency. Finally, to cater the increasing market of flexible electronics, a flexible Al-air battery is developed by impregnating the ethanol gel into a paper substrate, which can function normally even under serious deformation or damage.

关键词： Al-air battery Gel electrolyte Ethanol gel Al corrosion Polyethylene oxide

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Compressive properties of a novel slurry-infiltrated fiber concrete reinforced with arc-shaped steel fibers

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第6期24卷 543-556页

作者： Hedong LI yabiao LI yunfeng PAN P.L.NG Christopher K.y.leung Xin ZHAO School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Civil Engineering The University of Hong KongHong Kong 999077China Faculty of Civil Engineering Vilnius Gediminas Technical UniversityVilnius LT-10223Lithuania Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong Kong 999077China School of Civil Engineering and Architecture Zhejiang University of Science and TechnologyHangzhou 310023China

Slurry-infiltrated fiber concrete(SIFCON)is a sort of strain hardening cement-based composite material,typically made with 5%–20%steel *** study focused on a novel type of SIFCON in which hooked-end steel fibers were replaced by arc-shaped steel *** quasi-static compressive properties of the SIFCON were first *** results suggested that using arc-shaped steel fibers in lieu of hooked-end steel fibers increased the quasi-static compressive strength by 47.1%and the strain at peak stress by 56.3%.We attribute these improvements to new crack-resisting mechanisms,namely“fiber crosslock”,“dual bridging”,and“confinement loops”,when the arc-shaped steel fibers are introduced into *** high impact resistance is a special property of SIFCON that is of practical significance,the dynamic compressive properties of arc-shaped steel fiber SIFCON were studied by using an 80-mm-diameter split Hopkinson pressure bar(SHPB).The results showed that the dynamic compressive strength,dynamic increase factor(DIF),and dynamic toughness of SIFCON all increased with the strain *** SIFCON incorporating arc-shaped steel fibers proved to have significant advantages in structural applications requiring high impact resistance.

关键词： Slurry-infiltrated fiber concrete(SIFCON) Arc-shaped steel fiber Quasi-static compressive properties Spilt Hopkinson pressure bar(SHPB) Dynamic compressive properties

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