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Numerical modeling of fracture propagation of supercritical CO_(2)compound fracturing

Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2607-2628页

作者： Hao Chen yong Kang Wanchun jin Changhai Li Can Cai School of Mechanical Engineering Southwest Petroleum UniversityChengdu610500China Laboratory of High-pressure Jet Theory and Application Technology Southwest Petroleum UniversityChengdu610500China Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan UniversityWuhan430072China Sinopec International Petroleum Exploration and Production Corporation Beijing 100029China

The exploitation of shale gas is promising due to depletion of the conventional energy and intensification of the greenhouse *** this paper,we proposed a heat-fluid-solid coupling damage model of supercritical CO_(2)(SC-CO_(2))compound fracturing which is expected to be an efficient and environmentally friendly way to develop shale *** coupling model is solved by the finite element method,and the results are in good agreement with the analytical solutions and fracturing *** on this model,the fracture propagation characteristics at the two stages of compound fracturing are studied and the influence of pressurization rate,in situ stress,bedding angle,and other factors are *** results show that at the SC-CO_(2)fracturing stage,a lower pressurization rate is conducive to formation of the branches around main fractures,while a higher pressurization rate inhibits formation of the branches around main fractures and promotes formation of the main *** bedding and in situ stress play a dominant role in the fracture *** the in situ stress ratio(δ_(x)/δ_(y))is 1,the presence of bedding can reduce the initiation pressure and failure ***,it will cause the fracture to propagate along the bedding direction,reducing the fracture *** rocks without bedding,hydraulic fracturing has the lengthening and widening effects for SC-CO_(2)induced *** shale,fractures induced at the hydraulic fracturing stage are more likely to be dominated by in situ stresses and have a shorter reorientation ***,fracture branches propagating along the maximum principal stress direction may be generated around the main fractures induced by SC-CO_(2)at the hydraulic fracturing *** the branches converge with the main fractures,fracture zones are easily formed,and thus the fracture complexity and damage area can be significantly *** results are instructive for the design and application of SC

关键词： Compound fracturing Fracture propagation Finite element method Damage evolution

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Identification of FIR systems under difference-driven scheduled quantized observations

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Control Theory and Technology 2024年第2期22卷 163-172页

作者： Dong Liang Ruizhe Jia Fengwei jing yong Song jin Guo School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing100083China Key Laboratory of Knowledge Automation for Industrial Processes Ministry of EducationBeijing100083China National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing100083China

In networked system identification,how to effectively use communication resources and improve convergence speed is the focus of ***,there is an inherent contradiction between the two *** this paper,the event-driven communication is used to save communication resources for the identification of finite impulse response systems,and the input design is carried out to meet the requirements of convergence ***,a difference-driven communication is ***,the performance of the communication mechanism is analyzed,and the calculation method of its communication rate is *** that,according to the communication rate and the convergence rate of the identification algorithm,the input design problem is transformed into a constrained optimization problem,and the algorithm for finding the optimal solution is *** addition,considering the case that the output is quantized by multiple thresholds,the way to calculate its communication rate is given and the influence of threshold number on communication rate is ***,the effectiveness of the algorithm is verified by simulation.

关键词： System identification FIR system Difference-driven Quantized observation

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Influence of Micro/Nano-Ti Particles on the Corrosion Behavior of AZ31-Ti Composites

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 484-498页

作者： jinchao Jiao jin Zhang yong Lian Shengli Han Kaihong Zheng Fusheng Pan Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 10083China Beijing Key Laboratory for Corrosion Erosion and Surface Technology Beijing 100083China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 404100China

Adding Ti particles to magnesium alloy simultaneously enhances its strength and ***,how these particles influence on Mg alloy’s corrosion performance is seldom *** corrosion behavior of AZ31-Ti composites containing titanium nanoparticles(1.5 and 5 wt%)and micron particles(10 wt%)prepared by powder metallurgical in 3.5 wt%NaCl solution was *** results indicate that Ti particles serve as the primary location for the cathodic hydrogen reduction reaction,resulting in intense galvanic corrosion between the Ti and Mg *** nanoparticles distributed at the interface of the original AZ31 powder were in a discontinuous mesh structure,thus failing to act as a barrier against *** corrosion products with the existence of numerous cracks gradually peel off during the corrosion process and cannot protect the *** average corrosion rate P_(w) of AZ31,AZ31-1.5%Ti,AZ31-5%Ti,and AZ31-10%Ti after 7 days of immersion is 27.55,105.65,283.67,and 99.35 mm/y,***,AZ31-Ti composites can be considered as potential candidates for degradable fracturing ***,it is recommended to improve their corrosion resistance through surface treatment.

关键词： AZ31-Ti composite Nano-Ti Micro-Ti Corrosion behavior Scanning Kelvin probe force microscopy(SKPFM)

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Influence of pressure disturbance wave on dynamic response characteristics of liquid film seal for multiphase pump

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Petroleum Science 2024年第3期21卷 2048-2065页

作者： Qing-Ping Li jin-Ya Zhang Jia-Xiang Zhang yong-Xue Zhang CNOOC Research Institute Company Limited Beijing100028China State Key Laboratory of Natural Gas Hydrate Beijing100028China College of Mechanical and Transportation Engineering China University of PetroleumBeijing2249China

Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump *** mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation ***(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh *** results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually *** the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely *** maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance *** mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial *** with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and *** actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.

关键词： Multiphase pump Liquid film seal Pressure disturbance wave Dynamic response characteristics

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Achieving full mutualism with massive passive devices for multiuser MIMO symbiotic radio

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Science China(Information Sciences) 2024年第9期67卷 196-212页

作者： jingran XU Zhuoyin DAI yong ZENG Shi jin Tao JIANG National Mobile Communications Research Laboratory Southeast University Purple Mountain Laboratories Research Center of 6G Mobile Communications School of Cyber Science and Engineering and Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology

Symbiotic radio(SR) is one of the attractive communication technologies to facilitate largescale Internet of Things(IoT) connections with enhanced energy and spectrum efficiency, where passive backscatter devices(BDs) modulate their information over the radio frequency(RF) signals emitted by the active primary transmitters(PTs). Meanwhile, the primary transmission can be strengthened with the additional multipaths created by BDs. To capitalize to a greater extent on the mutualism relationship between the two types of communication, this paper studies multiple-input multiple-output(MIMO) SR communication systems including multiple PTs and massive BDs. We derive the achievable rate expressions of each PT and BD, as well as the sum rate expressions of primary and secondary communication, *** asymptotic analysis is given to derive the active and passive communication rates with a large number of BDs. Furthermore, for the general case with a finite number of BDs, we study the precoding optimization problem to maximize the sum rate of primary communication, while ensuring that the sum rate of secondary communication and the individual rate for each PT and BD in the prescribed active and passive user sets satisfy the specified thresholds. Simulation results are presented to verify the analytical studies.

关键词： multiuser MIMO SR backscattering massive backscatter devices asymptotic analysis active and passive communication

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Highly efficient capture of thorium ion by citric acid-modified chitosan gels from aqueous solution

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Chinese Chemical Letters 2024年第5期35卷 361-365页

作者： Linshan Peng Qihang Peng Tianxiang jin Zhirong Liu yong Qian State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China Jiangxi Province Key Laboratory of Polymer Micro/Nano Manufacturing and Devices East China University of TechnologyNanchang 330013China

A novel citric acid-modified chitosan gel(CSCA)was synthesized through a simple one-step process and was used to extract thorium ions from *** CSCA samples with varying chemical compositions were analyzed using SEM with mapping EDS,FT-IR,and static water contact angle measurements,and their adsorption behaviors were studied in *** results showed that the adsorption performance of CSCA improves with the increase of CA content in the *** possesses an impressive capacity for thorium adsorption of 279.8 mg/***,it showed an ultra-fast adsorption rate and reached equilibrium within 30 *** terms of recyclability,the CSCA still retained more than 86%of its initial adsorption capacity after 6 cycles of *** functional theory(DFT)analysis reveals that the good selectivity of this material towards thorium ions should be attributed to the high density of adsorption sites and strong interaction between carboxyl groups and thorium *** work could be beneficial in the design and synthesis of new polymer materials for extracting thorium.

关键词： Thorium Adsorption Citric acid Chitosan DFT calculation

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Effect of Shape and Placement of Twisted Pin Fins in a Rectangular Channel on Thermo-Hydraulic Performance

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Journal of Thermal Science 2024年第5期33卷 1773-1793页

作者： LI yong ZHANG jin ZHANG Yingchun ZHANG Jiajie MA Suxia SUNDEN Bengt XIE Gongnan College of Electrical and Power Engineering Taiyuan University of TechnologyTaiyuan 030024China Key Laboratory of Cleaner Intelligent Control on Coal&Electricity Ministry of EducationTaiyuan 030024China Shanxi Provincial Key Laboratory of High Efficiency Heat Storage and Low Carbon Heat Supply Taiyuan 030008China School of Energy and Power Engineering North University of ChinaTaiyuan 030051China Department of Energy Sciences Lund UniversityP.O.Box 118Lund SE 22100Sweden School of Marine Science and Technology Northwestern Polytechnical UniversityXi'an 710072China

To enhance the thermo-hydraulic performance of cooling channels,this investigation examines the influence of distinct cross-sectional shapes(i.e.,triangular,rectangular,and hexagonal)of twisted pin fins and their arrangements in straight and cross *** ambient air cooling test platform was established to numerically and experimentally investigate the flow and heat transfer characteristics of 360°twisted pin fins at Re=*** findings reveal that straight rows exhibit higher Nu values than cross rows for triangular and rectangular twisted pin fins,and Nu increases with *** contrast,for hexagonal twisted pin fins,only straight rows at Re=19000 exhibit superior overall thermal performance compared to cross ***,the heat transfer performance of the cooling channel with hexagonal twisted fins surpasses both triangular and rectangular configurations,especially at high Reynolds numbers(Re=22800).Although the heat transfer coefficient of the cooling channel with hexagonal twisted fins is significantly enhanced by 132.71%compared to the flat channel,it also exhibits the highest thermal resistance and relative friction among the three types of twisted fins,the maximum of which are 2.14 and ***,the hydrothermal performance factor(HTPF)of the cooling channels with different types of twisted pin fins depends on the Reynolds number and arrangement *** Re=15200,the highest HTPF achieved for the cross-row hexagonal twisted pin fins is 0.99.

关键词： twisted pin fin cross arrangement heat transfer pressure drop HTPF

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Engineering g-C_(3)N_(4)based materials for advanced photocatalysis:Recent advances

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Green Energy & Environment 2024年第2期9卷 166-197页

作者： Xin-Lian Song Lei Chen Li-Jiao Gao jin-Tao Ren Zhong-yong Yuan National Institute for Advanced Materials School of Materials Science and EngineeringSmart Sensing Interdisciplinary Science CenterNankai UniversityTianjin300350China Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Nankai UniversityTianjin300071China

Photocatalysis driven by abundant yet intermittent solar energy has considerable potential in renewable energy generation and environmental *** outstanding electronic structure and physicochemical properties of graphitic carbon nitride(g-C_(3)N_(4)),together with unique metal-free characteristic,make them ideal candidates for advanced photocatalysts *** review summarizes the up-to-date advances on g-C_(3)N_(4)based photocatalysts from ingenious-design strategies and diversified photocatalytic ***,the advantages,fabrication methods and limitations of each design strategy are systemically *** order to deeply comprehend the inner connection of theory–structure–performance upon g-C_(3)N_(4)based photocatalysts,structure/composition designs,corresponding photocatalytic activities and reaction mechanisms are jointly discussed,associated with introducing their photocatalytic applications toward water splitting,carbon dioxide/nitrogen reduction and pollutants degradation,***,the current challenges and future perspectives for g-C_(3)N_(4)based materials for photocatalysis are briefly *** design strategies and limitations are also instructive for constructing g-C_(3)N_(4) based materials in other energy and environment-related applications.

关键词： Graphitic carbon nitride g-C_(3)N_(4) Design strategies Photocatalysis Photocatalysts Reaction mechanism

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Secure symbol level precoding for cell-free network based on band-region constraint of the eavesdropper’s receiving signal

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High Technology Letters 2024年第3期30卷 304-309页

作者： LI Zewen jin yong FU Chunling PENG Xin HU Zhentao School of Artifical Intelligence Henan UniversityZhengzhou 450000P.R.China School of Physics and Electronics Henan UniversityKaifeng 475000P.R.China

A symbol level secure precoding scheme based on band-region constraint of the eavesdropper’s receiving signal is proposed to enhance the energy efficiency of cell-free multiple-input multiple-output(MIMO)networks in the presence of an eavesdropper while guaranteeing the quality of service(QoS)of user and the security of ***,to lighten its high computational complexity,original problem is divided into several cascade sub-problems firstly,and then those sub-problems are handled by combining Lagrangian dual function and improved Hooke-Jeeves method *** ex-periment with other secure symbol-level precoding schemes demonstrate that proposed scheme can achieve the lower power consumption with almost same symbol error rate and QoS of user.

关键词： cell-free symbol-level precoding(SLP) physical layer security(PLS) multi-ple-input multiple-output(MIMO) band-region constraint

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Analysis of lymph node metastasis and survival prognosis in early gastric cancer patients: A retrospective study

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World Journal of Gastrointestinal Surgery 2024年第6期16卷 1637-1646页

作者： Dong-Yuan Liu jin-jin Hu yong-Quan Zhou Ai-Rong Tan Department of General Surgery The 971st Hospital of Chinese People's Liberation ArmyQingdao 266071Shandong ProvinceChina Department of Chest Surgery Feicheng People's HospitalFeicheng 271600Shandong ProvinceChina Department of Gastrointestinal Surgery Zhongshan Hospital of Fudan UniversityShanghai 200032China Department of Oncology Qingdao Municipal HospitalQingdao 266000Shandong ProvinceChina

BACKGROUND Early gastric cancer(EGC)is a common malignant tumor of the digestive system,and its lymph node metastasis and survival prognosis have been *** retrospectively analyzing the clinical data of EGC patients,we can better under-stand the status of lymph node metastasis and its impact on survival and *** To evaluate the prognosis of EGC patients and the factors that affect lymph node METHODS The clinicopathological data of 1011 patients with EGC admitted to our hospital between January 2015 and December 2023 were collected in a retrospective cohort *** were 561 males and 450 *** mean age was 58±11 *** patient underwent radical *** status of lymph node metastasis in each group was determined according to the pathological examination results of surgical *** outcomes were as follows:(1)Lymph node metastasis in EGC patients;(2)Analysis of influencing factors of lymph node metastasis in EGC;and(3)Analysis of prognostic factors in patients with *** distributed measurement data are expressed as mean±SD,and a t test was used for comparisons between *** data are expressed as absolute numbers or percentages,and the chi-square test was used for comparisons between *** data were compared using a nonparametric rank sum test.A log-rank test and a logistic regression model were used for univariate analysis.A logistic stepwise regression model and a Cox stepwise regression model were used for multivariate *** Kaplan-Meier method was used to calculate the survival rate and construct survival curves.A log-rank test was used for survival *** Analysis of influencing factors of lymph node metastasis in *** results of the multifactor analysis showed that tumor length and diameter,tumor site,tumor invasion depth,vascular thrombus,and tumor differentiation degree were independent influencing factors for lymph node metastasis in patients with EGC(odds ratios=1.80,1.49,2.6

关键词： Gastric neoplasms Lymph node metastasis Prognosis Influencing factor Retrospective study

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