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Evaluation on the state of sand filling layer and the influence on segment deformation of immersed tunnels

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Underground Space 2024年第3期16卷 224-238页

作者： Ziyao Xu Ailan Che Chao Su School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China CCCC Second Harbor Engineering company Ltd. Wuhan 430040China

The immersed tunnel is considered an effective solution for traffic problems across rivers and *** sand filling layer,as an important part of immersed tunnel foundation treatments,directly affects segment attitude *** to difficulties in quality control of concealed construction and the complex hydrodynamic environment,the sand filling layer is prone to compaction defects,further leading to changes in segment ***,limited by structural concealment and state complexity,most studies consider the sand filling layer part of the foundation to study its impact on settlement while neglecting its influence on segment *** research proposes an evaluation method for the sand filling layer state based on elastic wave testing and the elastic wave characteristic parameters selected come from analysis of the time domain,frequency domain and time–frequency *** classifying the elastic wave characteristic parameters through the K-means clustering method,the relationship between the state of the sand filling layer and the elastic wave characteristic parameters is *** state of the sand filling layer is divided into dense,incompact,and void.A numerical model is established based on the Guangzhou BI-UT immersed tunnel with incompact and void sand filling layer states to simulate deformation and *** results indicate that the settlement of the tunnel segment is low in the eastern region and high in the western region due to the presence of a less dense sand filling layer,with a maximum differential settlement of 0.04 *** evaluation method plays a crucial role in guiding the construction of immersed tube tunnels.

关键词： Sand filling layer state Immersed tunnel Elastic wave test Clustering algorithm

CO_(2)flooding in shale oil reservoir with radial borehole fracturing for CO_(2)storage and enhanced oil recovery

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Petroleum Science 2024年第1期21卷 519-534页

作者： Jia-Cheng Dai Tian-Yu Wang Jin-Tao Weng Kang-Jian Tian Li-Ying Zhu Gen-Sheng Li State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China China National Oil and Gas Exploration and Development company Limited Beijing100034China

This study introduces a novel method integrating CO_(2)flooding with radial borehole fracturing for enhanced oil recovery and CO_(2)underground storage,a solution to the limited vertical stimulation reservoir volume in horizontal well fracturing.A numerical model is established to investigate the production rate,reservoir pressure field,and CO_(2)saturation distribution corresponding to changing time of CO_(2)flooding with radial borehole fracturing.A sensitivity analysis on the influence of CO_(2)injection location,layer spacing,pressure difference,borehole number,and hydraulic fractures on oil production and CO_(2)storage is *** CO_(2)flooding process is divided into four *** in layer spacing will significantly improve oil production rate and gas storage ***,serious gas channeling can occur when the spacing is lower than 20 *** the pressure difference between the producer and injector,the borehole number,the hydraulic fracture height,and the fracture width can also increase the oil production rate and gas storage *** analysis shows that layer spacing and fracture height greatly influence gas storage and oil *** outcomes are expected to provide a theoretical basis for the efficient development of shale oil reservoirs in the vertical direction.

关键词： Shale oil Radial borehole fracturing Embedded discrete fracture model Enhanced oil recovery Carbon storage

Thickening progression mechanism of silica fume-oil well cement composite system at high temperatures

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Petroleum Science 2024年第4期21卷 2793-2805页

作者： Hang Zhang Miao-Miao Hu Peng-Peng Li Guo-Qing Liu Qing-Lu Chang Jie Cao Ming Liu Wen-Hua Xu Xiu-Jian Xia Jin-Tang Guo School of Chemical Engineering and Technology Tianjin University Zhejiang Institute of Tianjin University Haihe Laboratory of Sustainable Chemical Transformations CNPC Engineering Technology R&D company Limited

This work studied the thickening progression mechanism of the silica fume-oil well cement composite system at high temperatures(110-180.C) in order to provide a theoretical guidance for the rational application of silica fume in the cementing engineering. Results showed that silica fume seldom affected the thickening progression of oil well cement slurry at 110-120.C, but when temperature reached above130.C, it would aggravate the bulging degree of thickening curves and significantly extend the thickening time, meanwhile causing the abnormal “temperature-based thickening time reversal” and“dosage-based thickening time reversal” phenomena in the range of 130-160.C and 170-180.C respectively. At 130-160.C, the thickening time of oil well cement slurry was mainly associated with the generation rate of calcium hydroxide(CH) crystal. The introduced silica fume would be attracted to the cement minerals' surface that were hydrating to produce CH and agglomerate together to form an“adsorptive barrier” to hinder further hydration of the inner cement minerals. This “adsorptive barrier”effect strengthened with the rising temperature which extended the thickening time and caused the occurrence of the “temperature-based thickening time reversal” phenomenon. At 170-180.C, the pozzolanic activity of silica fume significantly enhanced and considerable amount of C-S-H was generated, thus the “temperature-based thickening time reversal” vanished and the “dosage-based thickening time reversal” was presented.

关键词： Silica fume Oil well cement Thickening time reversal Pozzolanic reaction Adsorptive barrier CH and C−S−H

Optimal Scheduling Strategy of Source-Load-Storage Based onWind Power Absorption Benefit

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Energy Engineering 2024年第7期121卷 1823-1846页

作者： Jie Ma Pengcheng Yue Haozheng Yu Yuqing Zhang Youwen Zhang Cuiping Li Junhui Li Wenwen Qin Yong Guo State Grid Henan Economic Research Institute Zhengzhou450000China Zaozhuang Power Supply company State Grid Shandong Electric Power CompanyZaozhuang277000China Key Laboratory of Modern Power SystemSimulation and Control&Renewable Energy Technology Ministry of EducationNortheast Electric Power UniversityJilin132012China

In recent years,the proportion of installed wind power in the three north regions where wind power bases are concentrated is increasing,but the peak regulation capacity of the power grid in the three north regions of China is limited,resulting in insufficient local wind power consumption ***,this paper proposes a two-layer optimal scheduling strategy based on wind power consumption benefits to improve the power grid’s wind power consumption *** objective of the uppermodel is tominimize the peak-valley difference of the systemload,which ismainly to optimize the system load by using the demand response resources,and to reduce the peak-valley difference of the system load to improve the peak load regulation capacity of the *** lower scheduling model is aimed at maximizing the system operation benefit,and the scheduling model is selected based on the rolling *** load-side schedulingmodel needs to reallocate the absorbed wind power according to the response speed,absorption benefit,and curtailment penalty cost of the two DR dispatching ***,the measured data of a power grid are simulated by MATLAB,and the results show that:the proposed strategy can improve the power grid’s wind power consumption capacity and get a large wind power consumption benefit.

关键词： Wind power consumption two-layer optimal demand response rolling scheduling wind curtailment penalty

Unconventional photon blockade in the two-photon Jaynes–Cummings model with two-frequency cavity drivings and atom driving

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Chinese Physics B 2024年第2期33卷 164-168页

作者：刘欣田梦雨崔晓宁张馨鹤 School of Physics and Technology University of JinanJinan 250022China Marketing Service Center(Center of Metrology) State Grid ShanDong Electric Power CompanyJinan 250001China

In a two-frequency cavity driving and atom driving atom-cavity system,we find the photon blockade *** a truncated eigenstates space,we calculate the zero-delay second-order correlation function of the cavity mode analytically and obtain an optimal condition for the photon *** including three transition pathways,we find that higher excitations of the cavity mode can be further suppressed and the zero-delay second-order correlation function can be reduced *** on the master equation,we simulate the system evolution and find that the analytical solutions match well with the numerical *** scheme is robust with small fluctuations of parameters and may be used as a new type of single photon source.

关键词： photon blockade single photon source quantum interference

Acid-rock reaction kinetics in a two-scale model based on reaction order correction

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Petroleum Science 2024年第3期21卷 2089-2101页

作者： Xue-Song Li Ning Qi Ze-Hui Zhang Lian Liu Xia-Qing Li Xu-Hang Su School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Key Lab of Unconventional Oil&Gas Development Ministry of EducationChina University of Petroleum(East China)Qingdao26650ShandongChina SINOPEC Northwest Oilfield Branch company Urumqi830011XinjiangChina Petroleum Engineering Technology Research Institute SINOPEC Shengli Oilfield CompanyDongying257000ShandongChina

The reaction order plays a crucial role in evaluating the response rate of ***,the conventional two-scale model typically assumes that the reaction order is constant as one,which can lead to significant deviations from *** address this issue,this study proposes a novel multi-order dynamic model for acid-rock reaction by combining rotating disk experimental data with theoretical *** numerical simulations,this model allows for the investigation of the impact of acidification conditions on different orders of reaction,thereby providing valuable insights for on-site *** analysis reveals that higher response orders require higher optimal acid liquid flow rates,and lower optimal H+diffusion coefficients,and demonstrate no significant correlation with acid ***,it is recommended to increase the displacement and use high-viscosity acid for reservoirs with high calcite content,while reducing the displacement and using low-viscosity acid for reservoirs with high dolomite content.

关键词： Reaction order Two-scale model Wormhole propagation Carbonate rocks Numerical simulation

A Simple and Effective Surface Defect Detection Method of Power Line Insulators for Difficult Small Objects

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Computers, Materials & Continua 2024年第4期79卷 373-390页

作者： Xiao Lu Chengling Jiang Zhoujun Ma Haitao Li Yuexin Liu State Grid Jiangsu Electric Power Co. Ltd.Nanjing210024China State Grid Changzhou Power Supply company Changzhou213003China

Insulator defect detection plays a vital role in maintaining the secure operation of power *** address the issues of the difficulty of detecting small objects and missing objects due to the small scale,variable scale,and fuzzy edge morphology of insulator defects,we construct an insulator dataset with 1600 samples containing flashovers and *** a simple and effective surface defect detection method of power line insulators for difficult small objects is ***,a high-resolution featuremap is introduced and a small object prediction layer is added so that the model can detect tiny ***,a simplified adaptive spatial feature fusion(SASFF)module is introduced to perform cross-scale spatial fusion to improve adaptability to variable multi-scale ***,we propose an enhanced deformable attention mechanism(EDAM)*** integrating a gating activation function,the model is further inspired to learn a small number of critical sampling points near reference *** the module can improve the perception of object *** experimental results indicate that concerning the dataset of flashover and breakage defects,this method improves the performance of YOLOv5,YOLOv7,and *** practical application,it can simply and effectively improve the precision of power line insulator defect detection and reduce missing detection for difficult small objects.

关键词： Insulator defect detection small object power line deformable attention mechanism

Research on a Monte Carlo global variance reduction method based on an automatic importance sampling method

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Nuclear Science and Techniques 2024年第5期35卷 200-215页

作者： Yi-Sheng Hao Zhen Wu Shen-Shen Gao Rui Qiu Hui Zhang Jun-Li Li Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging of Ministry of Education Beijing 100084China Nuctech company Limited Beijing 100084China

Global variance reduction is a bottleneck in Monte Carlo shielding *** global variance reduction problem requires that the statistical error of the entire space is *** study proposed a grid-AIS method for the global variance reduction problem based on the AIS method,which was implemented in the Monte Carlo program *** proposed method was validated using the VENUS-Ⅲ international benchmark problem and a self-shielding calculation *** results from the VENUS-Ⅲ benchmark problem showed that the grid-AIS method achieved a significant reduction in the variance of the statistical errors of the MESH grids,decreasing from 1.08×10^(-2) to 3.84×10^(-3),representing a 64.00% *** demonstrates that the grid-AIS method is effective in addressing global *** results of the selfshielding calculation demonstrate that the grid-AIS method produced accurate computational ***,the grid-AIS method exhibited a computational efficiency approximately one order of magnitude higher than that of the AIS method and approximately two orders of magnitude higher than that of the conventional Monte Carlo method.

关键词： Monte Carlo Global variance reduction Reactor shielding Automatic importance sampling

A fuse-based DC circuit breaker with vacuum interrupter enhanced by an external transverse magnetic field

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High Voltage 2024年第3期9卷 710-720页

作者： Yu Xiao Yi Wu Yifei Wu Fei Yang Mingzhe Rong Zhuo Yang State Key Laboratory of Electrical Insulation and Power Equipment School of Electric EngineeringXi'an Jiaotong UniversityXi'anChina State Grid Shaanxi Electric Power company Limited Xi'anChina

Due to the increasing power system capacity,the interruption of large fault currents has gradually become a major challenge in power *** the moment,such currents are interrupted mainly via circuit breakers based on the method of active current ***,these types of circuit breakers tend to be costly and *** possible alternative—a fuse-based circuit breaker with current commutation process enhanced by an external transverse magnetic field(ETMF)—is proposed by the *** main advantage lies in the fast current commutation achieved by an ETMF-enhanced three-stage increase of the vacuum arc *** study of the current commutation process is mainly represented by the authors,and the influencing factors of the current commutation—contact opening speed and ETMF current—are *** last,the proposed circuit breaker is verified by an experiment,whose results show that a short-circuit current of 42 kA can be interrupted within just 2 ms.

关键词： vacuum transverse interrupt