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Numerical Analysis of Perforation during Hydraulic Fracture Initiation Based on Continuous-Discontinuous Element Method

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 2103-2129页

作者： Rui Zhang Lixiang wang Jing Li Chun Feng Yiming Zhang School of Civil and Transportation Engineering Hebei University of TechnologyTianjin300401China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou310018China Jinyun Institute Zhejiang Sci-Tech UniversityLishui321400China

Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing *** perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas *** this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CDEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design *** model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical ***-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation *** simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation *** findings show that perforations generated by the 39g DP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation ***,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.

关键词： Hydraulic fracturing real perforation shape breakdown pressure perforation layout design CDEM

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A Matching Algorithm with Reinforcement Learning and Decoupling Strategy for Order Dispatching in On-Demand Food Delivery

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Tsinghua Science and Technology 2024年第2期29卷 386-399页

作者： Jingfang Chen Ling wang Zixiao Pan Yuting Wu Jie Zheng Xuetao Ding Department of Automation Tsinghua UniversityBeijing 100084China Department of Delivery Technology MeituanBeijing 100102China

The on-demand food delivery(OFD)service has gained rapid development in the past decades but meanwhile encounters challenges for further improving operation *** order dispatching problem is one of the most concerning issues for the OFD platforms,which refer to dynamically dispatching a large number of orders to riders reasonably in very limited decision *** solve such a challenging combinatorial optimization problem,an effective matching algorithm is proposed by fusing the reinforcement learning technique and the optimization ***,to deal with the large-scale complexity,a decoupling method is designed by reducing the matching space between new orders and ***,to overcome the high dynamism and satisfy the stringent requirements on decision time,a reinforcement learning based dispatching heuristic is *** be specific,a sequence-to-sequence neural network is constructed based on the problem characteristic to generate an order priority ***,a training approach is specially designed to improve learning ***,a greedy heuristic is employed to effectively dispatch new orders according to the order priority *** real-world datasets,numerical experiments are conducted to validate the effectiveness of the proposed *** results show that the proposed algorithm can effectively solve the problem by improving delivery efficiency and maintaining customer satisfaction.

关键词： order dispatching on-demand delivery reinforcement learning decoupling strategy sequence-to-sequence neural network

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On Designs of Decentralized Reputation Management for Permissioned Blockchain Networks

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1755-1773页

作者： Jinyu Chen Long Shi Qisheng Huang Taotao wang Daojing He School of Electronic and Optical Engineering Nanjing University of Science and TechnologyNanjing210094China School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen518055China College of Electronics and Information Engineering Shenzhen UniversityShenzhen518060China School of Computer Science and Technology Harbin Institute of TechnologyShenzhen518055China

In permissioned blockchain networks,the Proof of Authority(PoA)consensus,which uses the election of authorized nodes to validate transactions and blocks,has beenwidely advocated thanks to its high transaction throughput and fault ***,PoA suffers from the drawback of centralization dominated by a limited number of authorized nodes and the lack of anonymity due to the round-robin block proposal *** a result,traditional PoA is vulnerable to a single point of failure that compromises the security of the blockchain *** address these issues,we propose a novel decentralized reputation management mechanism for permissioned blockchain networks to enhance security,promote liveness,and mitigate centralization while retaining the same throughput as traditional *** paper aims to design an off-chain reputation evaluation and an on-chain reputation-aided ***,we evaluate the nodes’reputation in the context of the blockchain networks and make the reputation globally verifiable through smart ***,building upon traditional PoA,we propose a reputation-aided PoA(rPoA)consensus to enhance securitywithout sacrificing *** particular,rPoA can incentivize nodes to autonomously form committees based on reputation authority,which prevents block generation from being tracked through the randomness of reputation ***,we develop a reputation-aided fork-choice rule for rPoA to promote the network’s ***,experimental results show that the proposed rPoA achieves higher security performance while retaining transaction throughput compared to traditional PoA.

关键词： Blockchain reputation management PoA throughput security decentralization

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MPI/OpenMP-Based Parallel Solver for Imprint Forming Simulation

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 461-483页

作者： Yang Li Jiangping Xu Yun Liu Wen Zhong Fei wang School of Mechanical Engineering Jiangsu UniversityZhenjiang212016China School of Mechanical Engineering Wuhan Polytechnic UniversityWuhan430023China Shenyang Mint Company Limited Shenyang110092China

In this research,we present the pure open multi-processing(OpenMP),pure message passing interface(MPI),and hybrid MPI/OpenMP parallel solvers within the dynamic explicit central difference algorithm for the coining process to address the challenge of capturing fine relief features of approximately 50 *** such precision demands the utilization of at least 7 million tetrahedron elements,surpassing the capabilities of traditional serial programs previously *** mitigate data races when calculating internal forces,intermediate arrays are introduced within the OpenMP *** helps ensure proper synchronization and avoid conflicts during parallel ***,in the MPI implementation,the coins are partitioned into the desired number of *** division allows for efficient distribution of computational tasks across multiple *** simulation examples are conducted to compare the three solvers with serial programs,evaluating correctness,acceleration ratio,and parallel *** results reveal a relative error of approximately 0.3%in forming force among the parallel and serial solvers,while the predicted insufficient material zones align with experimental ***,speedup ratio and parallel efficiency are assessed for the coining process *** pureMPI parallel solver achieves a maximum acceleration of 9.5 on a single computer(utilizing 12 cores)and the hybrid solver exhibits a speedup ratio of 136 in a cluster(using 6 compute nodes and 12 cores per compute node),showing the strong scalability of the hybrid MPI/OpenMP programming *** approach effectively meets the simulation requirements for commemorative coins with intricate relief patterns.

关键词： Hybrid MPI/OpenMP parallel computing MPI OpenMP imprint forming

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The short and long-term effect of polystyrene nanoplastics on nitrifying sludge at high nitrite concentrations

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Journal of Environmental Sciences 2024年第1期135卷 222-231页

作者： Xiaolong wang Jialu Huang Zhiqiang Qi Ruiqin Kang Chao Du Da Li School of Chemical and Environmental Engineering Anyang Institute of TechnologyAnyang 455000China Henan Licheng Environmental Technology Co. Ltd.Anyang 455000China State Key Laboratory of Urban Water Resource and Environment School of EnvironmentHarbin Institute of TechnologyHarbin 150090China

The effect of nanoplastics(NPs)on nitrite oxidation bacteria(NOB)community in treating high-strength wastewater remains unclear,which seriously affects the stability of nitrogen removal *** this study,highly active nitrifying sludge was enriched and exposed to 50nm polystyrene NPs(PS-NPs)for short-term(1,100,500,and 1000 mg/L,1.5 hr)and long-term(1,10,100 mg/L,40 days)at high nitrite *** contrast to previous studies,our results showed that the exposures to PS-NPs had little effect on nitrifying *** long-term exposure,the protein/polysaccharide ratios in extracellular polymeric substances(EPS)were positively correlated with PS-NPs concentrations(0.78–0.99).The produced reactive oxygen species(ROS)were gradually removed,and PS-NPs higher than 10 mg/L caused damage to membrane ***-term exposure for 40 days increased the community diversity and caused significant differences between the control and exposed *** control group were dominated by Nitrobacter and Exiguobacterium,while the exposure group was dominated by Bacillus,Mycobacterium,and Nitrospira.A noticeable shift in the NOB community from Nitrobacter(26.5%to 3.4%)to Nitrospira(1.61%to 14.27%)was observed.A KEGG analysis indicated a decrease in cell growth and death,cell motility and energy *** appeared that NOB could adapt to PS-NPs stress through enhanced secretion and removal of oxidative ***,this study provided new insights into the response mechanism of NOB to PS-NPs exposure.

关键词： Nanoplastics Nitrifying activity Extracellular polymeric substance(EPS) Exposure Community analysis

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Post-treatment of Ti-MWW zeolite with potassium fluoride for propylene epoxidation

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Frontiers of Chemical Science and Engineering 2024年第8期18卷 37-47页

作者： Xintong Li Xianchen Gong Jilong wang Shengbo Jin Hao Xu Peng Wu State Key Laboratory of Petroleum Molecular&Process Engineering Shanghai Key Laboratory of Green Chemistry and Chemical ProcessesSchool of Chemistry and Molecular EngineeringEast China Normal UniversityShanghai 200062China

Epoxidation of propylene to propylene oxide(PO)with hydrogen peroxide(HPPO)is an environmentally friendly and cost-efficient process in which titanosilicates are used as ***-MWW is a potential industrial catalyst for this process,which involves the addition of HPPO to *** silanol groups generated during secondary crystallization unavoidably result in ring-opening of PO and inefficient decomposition of HPPO,which diminish the PO selectivity and the lifespan of *** address this issue,we conducted post-treatment modifications of the structured Bf-Ti-MWW catalyst with potassium fluoride aqueous *** quenching the silanol groups with potassium fluoride and implanting electron-withdrawing fluoride groups into the Ti-MWW framework,both the catalytic activity and HPPO utilization efficiency were ***,the ring opening reaction of PO was *** a continuous fixed-bed liquid-phase propylene epoxidation reaction,the KF-treated structured Ti-MWW catalyst displayed an exceptionally long lifespan of 2700 h,with a PO yield of 590 g·kg^(-1)·h^(-1).

关键词： titanosilicates Ti-MWW propylene epoxidation structured catalyst KF modification

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Edge modes in finite-size systems with different edge terminals

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Chinese Physics B 2024年第10期33卷 381-387页

作者： Huiping wang Li Ren Xiuli Zhang Liguo Qin School of Mathematics Physics and StatisticsShanghai University of Engineering ScienceShanghai 201620China

We investigate the behavior of edge modes in the presence of different edge terminations and long-range(LR)***,we mainly focus on such model crystals with two different types of structures(type I:“…-P-Q-P-Q-…”and type II:“…=P-Q=P-Q=…”),where P and Q represent crystal lines(CLs),while the symbols“-”and“=”denote the distance between the nearest neighbor(NN)*** on the lattice model Hamiltonian with LR hopping,the existence of edge modes is determined analytically by using the transfer matrix method(TMM)when different edge terminals are taken into *** findings are consistent with the numerical results obtained by the exact diagonalization *** also notice that edge modes can exhibit different behaviors under different edge *** result is helpful in solving novel edge modes in honeycomb crystalline graphene and transition metal dichalcogenides with different edge terminals.

关键词： edge modes long-range hopping different edge terminals

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High Impedance Fault Detection Based on Attention Mechanism and Object Identification

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 197-207页

作者： Yongjie Zhang Xiaojun wang Yiping Luo Dahai Zhang Sohrab Mirsaeidi Jinghan He School of Electrical Engineering Beijing Jiaotong UniversityBeijing 100044China

Detection of high impedance faults(HIFs)has been traditionally a main challenge in the protection of distribution systems,since they do not generate enough current to be reliably detected by conventional over-current ***-based methods are alternative HIF detection methods which avoid threshold settings by training a classification or regression ***,most of them lack interpretability and are not compatible with various distribution *** paper proposes an object detection-based HIF detection method,which has higher visualization and can be easily applied to different ***,based on the analysis of HIFs,a Butterworth band-pass filter is designed for HIF harmonic feature ***,based on the synchronized data provided by distribution-level phasor measurement units,global HIF feature gray-scale images are formed through combining the topology information of the distribution *** further enhance the feature information,a locally excitatory globally inhibitory oscillator region attention mechanism(LEGIO-RAM)is proposed to highlight the critical feature regions and inhibit useless and fake ***,an object detection network based You Only Look Once(YOLO)v2 is established to achieve fast HIF detection and section *** obtained results from the simulation of the proposed approach on three different distribution networks and one realistic distribution network verify that the proposed method is highly effective in terms of reliability and generalization.

关键词： Attention mechanism distribution-level phasor measurement units high impedance faults object detection

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Screening of transition metal oxides for electrocatalytic nitrate reduction to ammonia at large currents

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Nano Research 2024年第5期17卷 3902-3910页

作者： Qiongfei Wu Weijie Zhu Dongxu Ma Chao Liang Zhoucheng wang Hanfeng Liang State Key Laboratory of Physical Chemistry of Solid Surfaces Tan Kah Kee Innovation LaboratoryCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China College of Chemical Engineering Tianjin UniversityTianjin 300072China

Electrochemical nitrate reduction reaction(NO_(3)RR)towards ammonia,as an emerging and appealing technology alternative to the energy-intensive Haber-Bosch process and inefficient nitrogen reduction reaction,has recently aroused wide concern and ***,the current research of the NO_(3)RR towards ammonia lacks the overall performance comparison of various *** this,we here make a comparison of 12 common transition metal oxide catalysts for the NO_(3)RR under a high cathodic current density of 0.25 A·cm^(-2),wherein Co_(3)O_(4) catalyst displays the highest ammonia Faradaic efficiency(85.15%)and moderate activity(ca.-0.25 V *** hydrogen electrode).Other external factors,such as nitrate concentrations in the electrolyte and applied potential ranges,have also been specifically investigated for the NO_(3)RR.

关键词： nitrate reduction reaction ammonia production transition metal oxides Co_(3)O_(4)

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Diverse atomic structure configurations of metal-doped transition metal dichalcogenides for enhancing hydrogen evolution

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Nano Research 2024年第5期17卷 3586-3602页

作者： Longlu wang Yuxin Zhang Chen Gu Haoxuan Yu Yanling Zhuang Zechao Zhuang College of Electronic and Optical Engineering and College of Flexible Electronics(Future Technology) Jiangsu Province Engineering Research Center for Fabrication and Application of Special Optical Fiber Materials and DevicesNanjing University of Posts and TelecommunicationsNanjing 210023China Department of Chemical Engineering Columbia UniversityNew YorkNY 10027USA

Doping foreign metal atoms into the substrate of transition metal dichalcogenides(TMDs)enables the formation of diverse atomic structure configurations,including isolated atoms,chains,and ***,it is very important to reasonably control the atomic structure and determine the structure-activity relationship between the atomic configurations and the hydrogen evolution reaction(HER)*** numerous studies have indicated that doping can yield diverse atomic structure configurations,there remains an incomplete understanding of the relationship between atomic configurations within the lattice of TMDs and their ***,diverse atomic structure configurations of adsorptive doping,substitutional doping,and TMDs alloys are *** structure-activity relationship between different atomic configurations and HER performance can be determined by micro-nanostructure devices and density functional theory(DFT)*** diverse atomic structure configurations are of great significance for activating the inert basal plane of TMDs and improving the catalytic activity of ***,we have summarized the current challenges and future opportunities,offering new perspectives for the design of highly active and stable metal-doped TMDs catalysts.

关键词： transition metal dichalcogenides(TMDs) dopant effect diverse atomic structure configurations hydrogen evolution reaction(HER)

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