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A semi-analytical model for coupled flow in stress-sensitive multi-scale shale reservoirs with fractal characteristics

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Petroleum Science 2024年第1期21卷 327-342页

作者： Qian Zhang Wen-Dong Wang Yu-Liang Su Wei Chen Zheng-Dong lei lei Li Yong-Mao Hao Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Shale Oil Development Branch Changqing Oilfield CompanyPetroChinaQingyang745708GansuChina PetroChina Research Institute of Petroleum Exploration&Development Beijing100083China

A large number of nanopores and complex fracture structures in shale reservoirs results in multi-scale flow of oil. With the development of shale oil reservoirs, the permeability of multi-scale media undergoes changes due to stress sensitivity, which plays a crucial role in controlling pressure propagation and oil flow. This paper proposes a multi-scale coupled flow mathematical model of matrix nanopores, induced fractures, and hydraulic fractures. In this model, the micro-scale effects of shale oil flow in fractal nanopores, fractal induced fracture network, and stress sensitivity of multi-scale media are considered. We solved the model iteratively using Pedrosa transform, semi-analytic Segmented Bessel function, Laplace transform. The results of this model exhibit good agreement with the numerical solution and field production data, confirming the high accuracy of the model. As well, the influence of stress sensitivity on permeability, pressure and production is analyzed. It is shown that the permeability and production decrease significantly when induced fractures are weakly supported. Closed induced fractures can inhibit interporosity flow in the stimulated reservoir volume (SRV). It has been shown in sensitivity analysis that hydraulic fractures are beneficial to early production, and induced fractures in SRV are beneficial to middle production. The model can characterize multi-scale flow characteristics of shale oil, providing theoretical guidance for rapid productivity evaluation.

关键词： Multi-scale coupled flow Stress sensitivity Shale oil Micro-scale effect Fractal theory

Strong,tough,and thermally conductive nacre-inspired boron nitride nanosheet/epoxy layered nanocomposites

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Nano Research 2024年第2期17卷 820-828页

作者： Huagao Wang Rongjian Lu lei Li Cheng Liang Jia Yan Rui Liang Guoxing Sun lei Jiang Qunfeng Cheng School of Chemistry Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of EducationBeihang UniversityBeijing 100191China School of Chemistry and Materials Science University of Science and Technology of ChinaHefei 230026China Suzhou Institute for Advanced Research University of Science and Technology of ChinaSuzhou 215123China Department of Stomatology Fifth Medical CenterChinese PLA General HospitalBeijing 100039China Department of Engineering Science Faculty of Innovation EngineeringMacao University of Science and TechnologyAvenida Wai LongTaipaMacao 999078 China Joint Key Laboratory of the Ministry of Education Institute of Applied Physics and Materials EngineeringUniversity of MacaoAvenida da UniversidadeTaipaMacao 999078China Institute of Energy Materials Science(IEMS) University of Shanghai for Science and TechnologyShanghai 200093China

Thermally conductive polymer nanocomposites integrated with lightweight,excellent flexural strength,and high fracture toughness(KIc)would be of great use in many ***,achieving all of these properties simultaneously remains a great *** by natural nacre,here we demonstrate a lightweight,strong,tough,and thermally conductive boron nitride nanosheet/epoxy layered(BNNEL)*** of the layered structure and enhancing the interfacial interactions through hydrogen bonding and Si–O–B covalent bonding,the resulting nacre-inspired BNNEL nanocomposites show high fracture toughness of~4.22 MPa·m^(1/2),which is 7 folds as high as pure ***,the BNNEL nanocomposites demonstrate sufficient flexural strength(~168.90 MPa,comparable to epoxy resin),while also being lightweight(~1.23 g/cm^(3)).Additionally,the BNNEL nanocomposites display a thermal conductivity(κ)of~0.47 W/(m·K)at low boron nitride nanosheet loading of 2.08 vol.%,which is 2.7 times higher than that of pure epoxy *** developed nacre-inspired strategy of layered structure design and interfacial enhancement provides an avenue for fabricating high mechanical properties and thermally conductive polymer nanocomposites.

关键词： nacre-inspiration nanocomposites flexural strength fracture toughness(KIc) thermal conductivity

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Science China Mathematics 2024年第2期67卷 405-430页

作者： Junzhuo Gao lei Wang Heng Lian School of Statistics and Data Science&LPMC Nankai UniversityTianjin 300071China Department of Mathematics City University of Hong KongHong KongChina

In this paper, we consider the unified optimal subsampling estimation and inference on the lowdimensional parameter of main interest in the presence of the nuisance parameter for low/high-dimensionalgeneralized linear models (GLMs) with massive data. We first present a general subsampling decorrelated scorefunction to reduce the influence of the less accurate nuisance parameter estimation with the slow convergencerate. The consistency and asymptotic normality of the resultant subsample estimator from a general decorrelatedscore subsampling algorithm are established, and two optimal subsampling probabilities are derived under theA- and L-optimality criteria to downsize the data volume and reduce the computational burden. The proposedoptimal subsampling probabilities provably improve the asymptotic efficiency of the subsampling schemes in thelow-dimensional GLMs and perform better than the uniform subsampling scheme in the high-dimensional GLMs.A two-step algorithm is further proposed to implement, and the asymptotic properties of the correspondingestimators are also given. Simulations show satisfactory performance of the proposed estimators, and twoapplications to census income and Fashion-MNIST datasets also demonstrate its practical applicability.

关键词： A-optimality decorrelated score subsampling high-dimensional inference L-optimality massive data

Advances in non-invasive imaging of proteinopathies in animal models of neurodegenerative diseases

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Neural Regeneration Research 2024年第10期19卷 2115-2116页

作者： lei Cao Bin Ji Ruiqing Ni Changes Technology Corporation Ltd. ShanghaiChina Fudan University ShanghaiChina School of Pharmacy Fudan UniversityShanghaiChina Institute for Biomedical Engineering University of Zurich&ETH Zurich Institute for Regenerative MedicineUniversity of ZurichZurichSwitzerland

Neurodegenerative diseases,including Alzheimer's disease(AD),frontotemporal dementia,Parkinson's disease,and dementia with Lewy bodies,represent tremendous unmet clinical needs.A common feature of these diseases is the aberrant cerebral accumulation of pathological protein aggregates,affecting selectively vulnerable circuits in a disease-specific *** studies have established a relationship between abnormal aggregation and neuronal dysfunction or loss,suggesting multifactorial pathogenesis mechanisms in these neurodegenerative disorders.

关键词： diseases degenerative clinical

Collaborative Charging Scheduling in Wireless Charging Sensor Networks

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Computers, Materials & Continua 2024年第4期79卷 1613-1630页

作者： Qiuyang Wang Zhen Xu lei Yang School of Electrical and Electronic Engineering Wuhan Polytechnic UniversityWuhan430048China

Wireless sensor networks (WSNs) have the trouble of limited battery power, and wireless charging provides apromising solution to this problem, which is not easily affected by the external environment. In this paper, we studythe recharging of sensors in wireless rechargeable sensor networks (WRSNs) by scheduling two mobile chargers(MCs) to collaboratively charge sensors. We first formulate a novel sensor charging scheduling problem with theobjective of maximizing the number of surviving sensors, and further propose a collaborative charging schedulingalgorithm(CCSA) for WRSNs. In the scheme, the sensors are divided into important sensors and ordinary *** can adaptively collaboratively charge the sensors based on the energy limit ofMCs and the energy demandof sensors. Finally, we conducted comparative simulations. The simulation results show that the proposed algorithmcan effectively reduce the death rate of the sensor. The proposed algorithm provides a solution to the uncertaintyof node charging tasks and the collaborative challenges posed by multiple MCs in practical scenarios.

关键词： Wireless rechargeable sensor network mobile charger collaborative charging adaptive charging

A GMM approach in coupling internal data and external summary information with heterogeneous data populations

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Science China Mathematics 2024年第5期67卷 1115-1132页

作者： Jun Shao Jinyi Wang lei Wang Key Laboratory of Advanced Theory and Application in Statistics and Data Science(East China Normal University) Ministry of EducationShanghai 200062China School of Statistics East China Normal UniversityShanghai 200062China Department of Statistics University of Wisconsin-MadisonWI 53706USA School of Statistics and Data Science KLMDASRLEBPS and LPMCNankai UniversityTianjin 300071China

Because of advances in data collection and storage,statistical analysis in modern scientific research and practice now has opportunities to utilize external information such as summary statistics from similar studies.A likelihood approach based on a parametric model assumption has been developed in the literature to utilize external summary information when the populations for external and main internal data are assumed to be the *** this article,we instead consider the generalized estimation equation(GEE)approach for statistical inference,which is semiparametric or nonparametric,and show how to utilize external summary information even when internal and external data populations are not the *** approach is coupling the internal data and external summary information to form additional estimation equations and then applying the generalized method of moments(GMM).We show that the proposed GMM estimator is asymptotically normal and,under some conditions,is more efficient than the GEE estimator without using external summary *** of the asymptotic covariance matrix of the GMM estimators are also *** results are obtained to confirm our theory and quantify the improvements by utilizing external *** example is also included for illustration.

关键词： adjustment for heterogeneity constraint data integration generalized method of moments summarystatistic

Quality assessment of friction-stir-welded aluminum alloy welds via three-dimensional force signals

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Advances in Manufacturing 2024年第1期12卷 61-75页

作者： Ji-Hong Dong Yi-Ming Huang Jia-lei Zhu Wei Guan Xu-Kai Ren Huan-Wei Yu lei Cui Beijing Institute of Petrochemical Technology Beijing102617People’s Republic of China Beijing Academy of Safety Engineering and Technology Beijing102617People’s Republic of China AVIC Manufacturing Technology Institute Beijing100024People’s Republic of China Tianjin Key Laboratory of Advanced Joining Technology School of Materials Science and EngineeringTianjin UniversityTianjin300350People’s Republic of China Shaoxing Special Equipment Testing Institute Shaoxing Key Laboratory of Special Equipment Intelligent Testing and EvaluationShaoxing312071ZhejiangPeople’s Republic of China

An online detection technology must be developed for realizing the real-time control of friction stir *** this study,the three-dimensional force exerted on a material during friction stir welding was collected synchronously and the relationship between the forces and welding quality was *** results indicated that the fluctuation period of the traverse force was equal to that of the lateral force during the stable welding *** phase difference between two horizontal forces wasπ/*** values of the horizontal forces increased with welding speed,whereas their amplitudes remained the *** proposed force model showed that the traverse and lateral forces conformed to an elliptical curve,and this result was consistent with the behavior of the measured *** variational mode decomposition was used to process the plunge *** intrinsic mode function that represented the real fluctuation in the plunge force varied at the same frequency as the spindle rotational *** tunnel defects occurred,the fluctuation period features were consistent with those obtained during normal welding,whereas the ratio parameter defined in this study increased significantly.

关键词： Friction stir welding(FSW) Three-dimensional force model Variational mode decomposition Tunnel defect

Improved Double Deep Q Network-Based Task Scheduling Algorithm in Edge Computing for Makespan Optimization

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Tsinghua Science and Technology 2024年第3期29卷 806-817页

作者： lei Zeng Qi Liu Shigen Shen Xiaodong Liu School of Computer Science Nanjing University of Information Science and TechnologyNanjing 210044China School of Software Nanjing University of Information Science and TechnologyNanjing 210044China School of Information Engineering Huzhou UniversityHuzhou 313000China School of Computing Edinburgh Napier UniversityEdinburghEH105DTUK

Edge computing nodes undertake an increasing number of tasks with the rise of business ***,how to efficiently allocate large-scale and dynamic workloads to edge computing resources has become a critical *** study proposes an edge task scheduling approach based on an improved Double Deep Q Network(DQN),which is adopted to separate the calculations of target Q values and the selection of the action in two networks.A new reward function is designed,and a control unit is added to the experience replay unit of the *** management of experience data are also modified to fully utilize its value and improve learning *** learning agents usually learn from an ignorant state,which is *** such,this study proposes a novel particle swarm optimization algorithm with an improved fitness function,which can generate optimal solutions for task *** optimized solutions are provided for the agent to pre-train network parameters to obtain a better cognition *** proposed algorithm is compared with six other methods in simulation *** show that the proposed algorithm outperforms other benchmark methods regarding makespan.

关键词： edge computing task scheduling reinforcement learning makespan Double Deep Q Network(DQN)

Research progress in performance improvement strategies and sulfur conversion mechanisms of Li-S batteries based on Fe series nanomaterials

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Nano Research 2024年第9期17卷 8045-8067页

作者： Ziyang Huang Zhenghua Wang lei Zhou Jun Pu Key Laboratory of Functional Molecular Solids(Ministry of Education) College of Chemistry and Materials ScienceAnhui Provincial Engineering Laboratory for New-Energy Vehicle Battery Energy-Storage MaterialsAnhui Normal UniversityWuhu 241000China School of Energy and Power Engineering Jiangsu UniversityZhenjiang 212013China Department of Electrical Engineering Eindhoven University of TechnologyEindhoven MB 5600The Netherlands

Lithium-sulfur(Li-S)batteries hold the potential to revolutionize energy storage due to the high theoretical capacity and energy ***,the commercialization process is seriously hindered by the rapid capacity decay and low utilization of sulfur,caused by the inevitable slow dynamics and the“shuttle effect”.The incorporation of metal-based electrocatalysts into sulfur cathodes shows promise in promoting the conversion of lithium polysulfides(LiPSs),reducing the“shuttle effect”,and enhancing cell kinetics and cycle *** these,Fe-based materials,characterized by environmental friendliness,low cost,abundant reserves,and high activity,are extensively used in sulfur cathode *** article reviews the advancements of Fe-based materials in enhancing Li-S batteries in recent *** from single/multi-component Fe-based metal compounds and single/bimetallic atoms,the influence of different Fe coordination environments on the conversion mechanism of LiPSs is *** is hoped that this review and the proposed prospects can further stimulate the development and application of the Fe element in Li-S batteries in the future.

关键词： Li-S batteries Fe-based nanomaterials shuttle effect reaction kinetics