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Exploring pore-scale production characteristics of oil shale after CO_(2) huff‘n’puff in fractured shale with varied permeability

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International Journal of Coal Science & Technology 2024年第1期11卷 194-203页

作者： Tianhan Xu jian wang Yuhao Lu Danling wang Li Yu Ye Tian State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500SichuanChina Institute for Carbon Neutrality Southwest Petroleum UniversityChengdu610500SichuanChina Research Institute of Shenzhen Branch of CNOOC(China)Co. LtdShenzhen518000GuangdongChina PetroChina Huabei Oilfield Company Cangzhou062552HebeiChina

Recent studies have indicated that the injection of carbon dioxide(CO_(2))can lead to increased oil recovery in fractured shale reservoirs following natural *** advancements in understanding mass exchange processes in subsurface formations,there remains a knowledge gap concerning the disparities in these processes between the matrix and fractures at the pore scale in formations with varying *** study aims to experimentally investigate the CO_(2) diffusion behaviors and in situ oil recovery through a CO_(2) huff‘n’puff process in the Jimsar shale oil *** achieve this,we designed three matrix-fracture models with different permeabilities(0.074 mD,0.170 mD,and 0.466 mD)and experimented at 30 MPa and 91°*** oil concentration in both the matrix and fracture was monitored using a low-field nuclear magnetic resonance(LF-NMR)technique to quantify in situ oil recovery and elucidate mass-exchange *** results showed that after three cycles of CO_(2) huff‘n’puff,the total recovery degree increased from 30.28%to 34.95%as the matrix permeability of the core samples increased from 0.074 to 0.466 mD,indicating a positive correlation between CO_(2) extraction efficiency and matrix *** similar fracture conditions,the increase in matrix permeability further promoted CO_(2) extraction efficiency during CO_(2) huff‘n’***,the increase in matrix permeability of the core had the greatest effect on the extraction of the first-cycle injection in large pores,which increased from 16.42%to 36.64%.The findings from our research provide valuable insights into the CO_(2) huff‘n’puff effects in different pore sizes following fracturing under varying permeability conditions,shedding light on the mechanisms of CO_(2)-enhanced oil recovery in fractured shale oil reservoirs.

关键词： Shale reservoir Hydraulic fracturing CO_(2)huff‘n’puff NMR Production characteristics

Predicting Rock Burst in Underground Engineering Leveraging a Novel Metaheuristic-Based LightGBM Model

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 229-253页

作者： Kai wang Biao He Pijush Samui jian Zhou No.Three Engineering Co. Ltd.CCCC First Highway Engineering CompanyBeijing101102China department of Civil Engineering Faculty of EngineeringUniversiti MalayaKuala Lumpur50603Malaysia department of Civil Engineering National Institute of Technology PatnaBihar800005India School of Resources and Safety Engineering Central South UniversityChangsha410083China

Rock bursts represent a formidable challenge in underground engineering,posing substantial risks to both infrastructure and human *** sudden and violent failures of rock masses are characterized by the rapid release of accumulated stress within the rock,leading to severe seismic events and structural ***,the development of reliable prediction models for rock bursts is paramount to mitigating these *** study aims to propose a tree-based model—a Light Gradient Boosting Machine(LightGBM)—to predict the intensity of rock bursts in underground engineering.322 actual rock burst cases are collected to constitute an exhaustive rock burst dataset,which serves to train the *** population-basedmetaheuristic algorithms are used to optimize the hyperparameters of the LightGBM ***,the sensitivity analysis is used to identify the predominant factors that may incur the occurrence of rock *** results show that the population-based metaheuristic algorithms have a good ability to search out the optimal hyperparameters of the LightGBM *** developed LightGBM model yields promising performance in predicting the intensity of rock bursts,with which accuracy on training and testing sets are 0.972 and 0.944,*** sensitivity analysis discloses that the risk of occurring rock burst is significantly sensitive to three factors:uniaxial compressive strength(σc),stress concentration factor(SCF),and elastic strain energy index(Wet).Moreover,this study clarifies the particular impact of these three factors on the intensity of rock bursts through the partial dependence plot.

关键词： Rock burst prediction LightGBM coati optimization algorithm pelican optimization algorithm partial dependence plot

Autonomous multi-drone racing method based on deep reinforcement learning

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Science China(Information Sciences) 2024年第8期67卷 35-48页

作者： Yu KANG jian DI Ming LI Yunbo ZHAO Yuhui wang department of Automation University of Science and Technology of China Institute of Advanced Technology University of Science and Technology of China Institute of Artificial Intelligence Hefei Comprehensive National Science Center College of Automation Engineering Nanjing University of Aeronautics and Astronautics

Racing drones have attracted increasing attention due to their remarkable high speed and excellent maneuverability. However, autonomous multi-drone racing is quite difficult since it requires quick and agile flight in intricate surroundings and rich drone interaction. To address these issues, we propose a novel autonomous multi-drone racing method based on deep reinforcement learning. A new set of reward functions is proposed to make racing drones learn the racing skills of human experts. Unlike previous methods that required global information about tracks and track boundary constraints, the proposed method requires only limited localized track information within the range of its own onboard sensors. Further, the dynamic response characteristics of racing drones are incorporated into the training environment, so that the proposed method is more in line with the requirements of real drone racing scenarios. In addition, our method has a low computational cost and can meet the requirements of real-time racing. Finally, the effectiveness and superiority of the proposed method are verified by extensive comparison with the state-of-the-art methods in a series of simulations and real-world experiments.

关键词： autonomous multi-drone racing deep reinforcement learning Markov game racing drone sim-to-real

Biomimetic soft robotic wrist with 3-DOF motion and stiffness tunability based on ring-reinforced pneumatic actuators and a particle jamming joint

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Science China(Technological Sciences) 2024年第3期67卷 774-790页

作者： HU TeTe LU Xinjiang YI jian wang YuHui XU Du State Key Laboratory of Precision Manufacturing for Extreme Service Performance School of Mechanical and Electrical EngineeringCentral South UniversityChangsha 410083China

The human wrist, a complex articulation of skeletal muscles and two-carpal rows, substantially contributes to improvements in maneuverability by agilely performing three-degree-of-freedom(3-DOF) orienting tasks and regulating stiffness according to variations in interaction forces. However, few soft robotic wrists simultaneously demonstrate dexterous 3-DOF motion and variable stiffness;in addition, they do not fully consider a soft-rigid hybrid structure of integrated muscles and two carpal *** this study, we developed a soft-rigid hybrid structure to design a biomimetic soft robotic wrist(BSRW) that is capable of rotating in the x and y directions, twisting around the z-axis, and possessing stiffness-tunable capacity. To actuate the BSRW, a lightweight soft-ring-reinforced bellows-type pneumatic actuator(SRBPA) with large axial, linear deformation(η_(lcmax)=70.6%,η_(lemax)=54.3%) and small radial expansion(η_(demax)=3.7%) is designed to mimic the motion of skeletal muscles. To represent the function of two-carpal rows, a compact particle-jamming joint(PJJ) that combines particles with a membrane-covered ballsocket mechanism is developed to achieve various 3-DOF motions and high axial load-carrying capacity(>60 N). By varying the jamming pressure, the stiffness of the PJJ can be adjusted. Finally, a centrally positioned PJJ and six independently actuated SRBPAs, which are in an inclined and antagonistic arrangement, are sandwiched between two rigid plates to form a flexible,stable, and compact BSRW. Such a structure enables the BSRW to have a dexterous 3-DOF motion, high load-carrying ability,and stiffness tunability. Experimental analysis verify 3-DOF motion of BSRW, producing force of 29.6 N and 36 N and torque of2.2 Nm in corresponding rotations. Moreover, the range of rotational angle and stiffness-tuning properties of BSRW are studied by applying jamming pressure to the PJJ. Finally, a system combining a BSRW and a soft enclosing gripper is proposed to demo

关键词： pneumatic soft actuators particle jamming robotic wrist soft robotics stiffness-tunable

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Trend of Storm Surge Induced by Typical Landfall Super Typhoons During 1975–2021 in the Eastern China Sea

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Journal of Ocean University of China 2024年第2期23卷 277-286页

作者： LUO Feng wang Yi TAO Aifeng SHI jian wang Yongzhi ZHANG Chi College of Harbour Coastal and Offshore EngineeringHohai UniversityNanjing 210098China Nantong Ocean and Coastal Engineering Research Institute Hohai UniversityNantong 226000China Key Laboratory of Ministry of Education for Coastal Disaster and Protection Hohai UniversityNanjing 210098China College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China The First Institute of Oceanography MNRQingdao 266061China

Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast and thus cause casualties,economic losses,and environmental *** a 3D tidal model,we reconstructed the typhoon(TY)wind field to simulate the storm surge induced by typical *** TY activity was then analyzed using historical *** showed a downtrend of varying degrees in the annual frequency of STYs and TCs in the Western North Pacific(WNP)Basin,with a significant trend change observed for TCs from 1949 to 2021.A large difference in the interannual change in frequency was found between STYs and TCs in the WNP and Eastern China Sea(ECS).Along the coast of EC,the frequency of landfall TCs showed a weak downtrend,and the typical STYs showed reverse micro growth with peak activity in ***,Fujian,and Taiwan were highly vulnerable to the frontal hits of typical *** by climate change,the average lifetime maximum intensity(LMI)locations and landfall locations of typical STYs in the ECS basin showed a significant poleward migration *** addition,the annual average LMI and accumulated cyclone energy showed an uptrend,indicating the increasing severity of the disaster *** by the typical STY activity in the ECS,the maximum storm surge area also showed poleward migration,and the coast of North China faced potential growth in high storm surge risks.

关键词： storm surge super typhoons tropical cyclones eastern China Sea poleward migration

Snowpack variations and their hazardous effects under climate warming in the central Tianshan Mountains

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Advances in Climate Change Research 2024年第3期15卷 442-451页

作者： jian-Sheng HAO Yan wang Lan-Hai LI Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences(CAS)Beijing 100101China Xinjiang Key Laboratory of Water Cycle and Utilization in Arid Zone Urumqi 830011China State Key Laboratory of desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China Tianshan Snowcover and Avalanche Observation and Research Station of Xinjiang Xinyuan 835800China CAS Research Center for Ecology and Environment of Central Asia Urumqi 830011China

Climate change alters snowpack evolution,which in turn influences the likelihood of snow avalanches and flood *** lack of systemic observational data on key snow characteristics in high mountains remains a scientific challenge in terms of systematically elucidating the dynamic chain of variations in climate-snowpack-snow *** restricts our understanding and poses challenges in the prediction of snow-related disaster *** such,this study analysed the variations of temperature and snowfall and the physical characteristics of snowpacks based on ground-based observations from the Kunse River Valley situated in the Tianshan Mountains from 1967 to *** results reveal that the temperature increased significantly by 0.32°C per decade(pdecade(pdepths increased along with an increase in peak snow water equivalent,thus indicating a higher frequency of extremely scarce or abundant snow *** low snowpack temperature gradient and earlier snowmelt dates in spring lead to earlier occurrences of snowmelt floods and wet *** the risks of these events increase,they pose greater threats to farmlands,road transportation,water-electricity infrastructure and several other human ***,these insights are critical for providing vital information that can deepen our understanding of the impact of climate change on snowpack characteristics and improve management strategies for snow-related disaster prevention and mitigation.

关键词： Climate change Snowpack variations Snow-related disaster Tianshan Mountains

Efficacy of scraping therapy on blood pressure and sleep quality in stage Ⅰ and Ⅱ essential hypertension: A systematic review and meta-analysis

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Journal of Integrative Medicine 2024年第1期22卷 12-21页

作者： Zheng-gang Zhu jian-ru wang Xiao-yan Pan School of Nursing Hunan University of Chinese MedicineChangsha 410208Hunan ProvinceChina School of Health Sciences Universiti Sains MalaysiaKubang Kerian 16150KelantanMalaysia department of Cardiovascular Medicine the First Affiliated Hospital of Henan University of Chinese MedicineZhengzhou 450000Henan ProvinceChina

Background Scraping therapy is widely used in treating stage I and II essential hypertension in ***,there has been no systematic evaluation of the efficacy of scraping therapy on blood pressure and sleep quality in stage I and II essential *** strategy Seven electronic databases(PubMed,Scopus,Cochrane Library,Web of Science,EBSCO,China National Knowledge Infrastructure and Wanfang Data electronic databases)were searched from inception to december *** on the principle of combining subject words with text words,the search strategy was constructed around search terms for“scraping therapy,”“scraping,”“Guasha,”“Gua sha,”“hypertension,”and“high blood pressure”during the database *** criteria Randomized controlled trials(RCTs)were included if they recruited patients with stage I and II essential hypertension and included a scraping therapy *** intervention group received antihypertensive drugs and scraping therapy,while the control group only took antihypertensive *** extraction and analysis Review Manager 5.4.0 and STATA 15.1 were used to enter all the relevant outcome variables to conduct the *** quality of the selected RCTs was assessed using the PEDro *** sensitivity analysis was carried out by iteratively excluding individual studies and repeating the analysis to determine the stability of the findings and identify any studies with greater influence on the *** analysis was performed to find the source of *** plots were used to evaluate the publication bias of included *** Nine RCTs including 765 participants were ***-analysis showed that scraping therapy combined with medication had an advantage over the use of medication alone in lowering systolic blood pressure(mean difference[MD]=?5.09,95%confidence interval[CI]=?6.50 to?3.67,P<0.001)and diastolic blood pressure(MD=?2.66,95%CI=?3.17 to?2.14,P<0.001).Subgroup analysis showed tha

关键词： Scraping therapy Essential hypertension Efficacy Blood pressure Sleep quality Systematic review Meta-analysis

Global Spherically Symmetric Solutions for a Coupled Compressible Navier–Stokes/Allen–Cahn System

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Acta Mathematica Sinica,English Series 2024年第8期40卷 2037-2064页

作者： Chang Ming SONG jian Lin ZHANG Yuan Yuan wang department of Applied Mathematics School of Mathematics and Information ScienceZhongyuan University of TechnologyZhengzhou 450007P.R.China

In this paper,we consider the global spherically symmetric solutions for the initial boundary value problem of a coupled compressible Navier–Stokes/Allen–Cahn system which describes the motion of two-phase viscous compressible *** prove the existence and uniqueness of global classical solution,weak solution and strong solution under the assumption of spherically symmetry condition for initial dataρ0 without vacuum state.

关键词： Diffuse interface model global solutions Navier-Stokes equations Allen-Cahn equation spherically symmetry

Enhanced plasticity of spontaneous coagulation cast oxide ceramic green bodies

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Journal of Advanced Ceramics 2024年第5期13卷 568-578页

作者： Juanjuan wang Jin Zhao Junyan Mao Wenlong Liu Haohao Ji jian Zhang Shiwei wang State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

In the preparation of large-sized ceramics,the use of a green body with relatively high plasticity is crucial to minimize the risk of cracking during *** achieve this goal,glycerol and polyethylene glycol(PEG)were utilized as plasticizers in the shaping of green bodies of oxide ceramics through spontaneous coagulation casting(SCC).This study investigated the effects of plasticizers and particle sizes ranging from the submicron to nanoscale on the slurry viscosity,drying shrinkage of wet gels,and mechanical properties of green *** plasticity of the green bodies was assessed by measuring the impact toughness and flexural stress‒strain *** incorporating an appropriate plasticizer,the peak width of the flexural stress‒strain curve for dried green bodies from particles of different sizes was nearly twice that without plasticizers,and the impact toughness was enhanced by approximately 71%,34%,and 41%when the particle size decreased from the submicron scale to the nanoscale(0.45μm,0.18μm,and 50 nm,respectively).The drilling test revealed that there was nearly no cracking around the holes in the green bodies with *** plasticity mechanism of the green bodies was examined based on ultraviolet–visible(UV–Vis)spectroscopy and scanning electron microscopy(SEM).It was discovered that plasticizers might mitigate the brittleness of green bodies by adjusting the interactions between molecules and modifying the gel network properly.

关键词： green body plasticity plasticizer particle size impact toughness stress-strain curve