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Novel damage constitutive models and new quantitative identification method for stress thresholds of rocks under uniaxial compression

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Journal of Central South University 2024年第8期31卷 2658-2675页

作者： Du, Kun Yi, Yang Luo, Xin-yao Liu, Kai Li, Peng Wang, Shao-feng School of Resources and Safety Engineering Central South University Changsha China Zhongnan Engineering corporation limited Power Construction Corporation of China Changsha China

Four key stress thresholds exist in the compression process of rocks, i. e., crack closure stress (σcc), crack initiation stress (σci), crack damage stress (σcd) and compressive strength (σc). The quantitative identifications of the first three stress thresholds are of great significance for characterizing the microcrack growth and damage evolution of rocks under compression. In this paper, a new method based on damage constitutive model is proposed to quantitatively measure the stress thresholds of rocks. Firstly, two different damage constitutive models were constructed based on acoustic emission (AE) counts and Weibull distribution function considering the compaction stages of the rock and the bearing capacity of the damage element. Then, the accumulative AE counts method (ACLM), AE count rate method (CRM) and constitutive model method (CMM) were introduced to determine the stress thresholds of rocks. Finally, the stress thresholds of 9 different rocks were identified by ACLM, CRM, and CMM. The results show that the theoretical stress - strain curves obtained from the two damage constitutive models are in good agreement with that of the experimental data, and the differences between the two damage constitutive models mainly come from the evolutionary differences of the damage variables. The results of the stress thresholds identified by the CMM are in good agreement with those identified by the AE methods, i.e., ACLM and CRM. Therefore, the proposed CMM can be used to determine the stress thresholds of rocks.

关键词： stress threshold acoustic emission damage constitutive model damage element quantitative method

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Development of a DFN-based probabilistic block theory approach for bench face angle design in open pit mining

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3047-3062页

作者： Jianhua Yan Xiansen Xing Zhihai Li Weida Ni Liuyuan Zhao Chun Zhu Yuanyuan He School of Earth Sciences and Engineering Hohai UniversityNanjing210098China POWERchina Huadong Engineering corporation limited Hangzhou311122China Zhejiang Huadong Construction corporation limited Hangzhou310004China The Seventh Geological Brigade of Hubei Geological Bureau Yichang443000China

In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation *** this reason,bench face angle,as one of the controlling parameters associated with block instabilities,should be carefully designed for sustainable *** study introduces a discrete fracture network(DFN)-based probabilistic block theory approach for the fast design of the bench face angle.A major advantage is the explicit incorporation of discontinuity size and spatial distribution in the procedure of key blocks *** proposed approach was applied to a granite mine in ***,DFN models were generated from a multi-step modeling procedure to simulate the complex structural characteristics of pit ***,a modified key blocks searching method was applied to the slope faces modeled,and a cumulative probability of failure was obtained for each ***,a bench face angle was determined commensurate with an acceptable risk level of *** simulation results have shown that the number of hazardous traces exposed on the slope face can be significantly reduced when the suggested bench face angle is adopted,indicating an extremely low risk of uncontrolled block instabilities.

关键词： Open pit mine Bench face angle Block theory Probabilistic approach Discrete fracture network modeling Fractured rock slope

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A Novel ISSA–DELM Model for Predicting Rock Mass Permeability

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2825-2848页

作者： Chen Xing Leihua Yao Yingdong Wang School of Engineering and Technology China University of Geosciences(Beijing)Beijing100083China Beijing Engineering corporation limited Beijing100024China

In pumped storage projects,the permeability of rock masses is a crucial parameter in engineering design and *** rock mass permeability coefficient(K)is influenced by various geological parameters,and previous studies aimed to establish an accurate relationship between K and geological *** study uses the improved sparrow search algorithm(ISSA)to optimize the parameter settings of the deep extreme learning machine(DELM),constructing a prediction model with flexible parameter selection and high ***,the Spearman method is applied to analyze the correlation between geological parameters.A sample database is built by comprehensively selecting four geological indexes:burial depth,rock quality designation(RQD),fracture density characteristic index(FD),and rock mass integrity designation(RID).Hence,the defects of the sparrow search algorithm(SSA)are enhanced using the improved strategy,and the initial input weights of the DELM are ***,the proposed ISSA–DELM model is employed to predict the permeability coefficient of rock mass in the entire study *** results showed that the predictive performance of the model is superior to that of the DELM and SSA–***,this model successfully provides insights into the distribution characteristics of rock mass permeability at engineering sites.

关键词： ISSA DELM rock mass permeability coefficient geological parameter correlation analysis

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Fine-grained grid computing model for Wi-Fi indoor localization in complex environments

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Journal of Electronic Science and Technology 2024年第1期22卷 42-52页

作者： Yan Liang Song Chen Xin Dong Tu Liu School of Computer Engineering Chengdu Technological UniversityChengdu611730China HAN Networks corporation limited Beijing100094China

The fingerprinting-based approach using the wireless local area network(WLAN)is widely used for indoor ***,the construction of the fingerprint database is quite *** when the position of the access point(AP)or wall changes,updating the fingerprint database in real-time is *** appropriate indoor localization approach,which has a low implementation cost,excellent real-time performance,and high localization accuracy and fully considers complex indoor environment factors,is preferred in location-based services(LBSs)*** this paper,we proposed a fine-grained grid computing(FGGC)model to achieve decimeter-level localization *** points(RPs)are generated in the grid by the FGGC ***,the received signal strength(RSS)values at each RP are calculated with the attenuation factors,such as the frequency band,three-dimensional propagation distance,and walls in complex *** a result,the fingerprint database can be established automatically without manual measurement,and the efficiency and cost that the FGGC model takes for the fingerprint database are superior to previous *** proposed indoor localization approach,which estimates the position step by step from the approximate grid location to the fine-grained location,can achieve higher real-time performance and localization accuracy *** mean error of the proposed model is 0.36 m,far lower than that of previous ***,the proposed model is feasible to improve the efficiency and accuracy of Wi-Fi indoor *** also shows high-accuracy performance with a fast running speed even under a large-size *** results indicate that the proposed method can also be suitable for precise marketing,indoor navigation,and emergency rescue.

关键词： Fine-grained grid computing (FGGC) Indoor localization Path loss Random forest Reference points(RPs)

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Mussel-inspired PTW@PDA composites for developing high-energy gun propellants with reduced erosion and enhanced mechanical strength

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Defence Technology（防务技术） 2024年第2期32卷 675-690页

作者： Xijin Wang Zhitao Liu Pengfei Sun Feiyun Chen Bin Xu Xin Liao School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina china North Industries Group corporation limited Beijing 100045China

The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun *** address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing *** interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW *** to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded *** 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of *** the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic *** strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.

关键词： High energy gun propellant Potassium titanate whiskers Polydopamine modification Erosion inhibitors Mechanical reinforcing fillers

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Dynamic Scene Graph Generation of Point Clouds with Structural Representation Learning

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Tsinghua Science and Technology 2024年第1期29卷 232-243页

作者： Chao Qi Jianqin Yin Zhicheng Zhang Jin Tang School of Artificial Intelligence Beijing University of Posts and TelecommunicationsBeijing 100876China Standard and Metrology Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China

Scene graphs of point clouds help to understand object-level relationships in the 3D *** graph generation methods work on 2D structured data,which cannot be used for the 3D unstructured point cloud *** point-cloud-based methods generate the scene graph with an additional graph structure that needs labor-intensive manual *** address these problems,we explore a method to convert the point clouds into structured data and generate graphs without given ***,we cluster points with similar augmented features into groups and establish their relationships,resulting in an initial structural representation of the point ***,we propose a Dynamic Graph Generation Network(DGGN)to judge the semantic labels of targets of different *** dynamically splits and merges point groups,resulting in a scene graph with high *** show that our methods outperform other baseline *** output reliable graphs describing the object-level relationships without additional manual labeled data.

关键词： scene graph generation structural representation point cloud

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The reservoir characteristics and their controlling factors of the sublacustrine fan in the Paleogene Dongying Formation, Bohai Sea,china

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Journal of Palaeogeography 2024年第1期13卷 127-148页

作者： Xiao-Jun Pang Guan-Min Wang Meng Zhao Qing-Bin Wang Xue-Fang Zhang School of Geosciences China University of Petroleum(East China)QingdaoShandong 266580China Tianjin Branch of china National Offshore Oil corporation limited Tianjin 300459China

Sublacustrine fan is an important element in continental lacustrine basins and is significant for reservoir exploration. Oil and gas resources have been found in the sublacustrine fan sandstone reservoirs of the Paleogene Dongying Formation in the Bohai Sea. In this study, the characteristics of the sublacustrine fan reservoirs and the controlling factors are studied using information from logging, cores, physical properties,casting thin sections, X-ray diffraction of clay minerals, vitrinite reflectance, rock pyrolysis, manometry data,and 3D seismic data. The sublacustrine fans of the Dongying Formation in the LD10, QHD34, and BZ21 structures show high-quality reservoirs with porosity >15 % and permeability >5 m D. The main controlling factors of the high-quality reservoirs are attributed to the favorable sedimentary facies type and negligible compaction,and cementation, substantial dissolution of K-feldspar, overpressure, and the development of faults and fractures. A high-quality sublacustrine fan reservoir model has been established to explain how these factors affected the physical properties. The favorable targets for oil and gas exploration in the Dongying Formation of Bohai Sea include undercompacted sandy debris flow reservoirs showing the dissolution of K-feldspar, and the reservoirs which are connected to the source rocks by faults. This study provides insights to establish the relationship between sedimentology, diagenesis and reservoir quality. The results of this study are significant for the exploration and development of the sublacustrine fan sandstone reservoirs in the Bohai Sea and analogous sandstone reservoirs elsewhere.

关键词： Sublacustrine fan High-quality reservoir Dissolution Overpressure Fault Bohai Sea

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Multi-scale Modeling and Finite Element Analyses of Thermal Conductivity of 3D C/SiC Composites Fabricating by Flexible-Oriented Woven Process

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 275-288页

作者： Zheng Sun Zhongde Shan Hao Huang Dong Wang Wang Wang Jiale Liu Chenchen Tan Chaozhong Chen Nanjing University of Aeronautics and Astronautics Nanjing 210016China School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China CRRC Institute corporation limited Beijing 100070China

Thermal conductivity is one of the most significant criterion of three-dimensional carbon fiber-reinforced SiC matrix composites(3D C/SiC).Represent volume element(RVE)models of microscale,void/matrix and mesoscale proposed in this work are used to simulate the thermal conductivity behaviors of the 3D C/SiC *** entirely new process is introduced to weave the preform with three-dimensional orthogonal *** 3D steady-state analysis step is created for assessing the thermal conductivity behaviors of the composites by applying periodic temperature boundary *** RVE models of cuboid,hexagonal and fiber random distribution are respectively developed to comparatively study the influence of fiber package pattern on the thermal conductivities at the ***,the effect of void morphology on the thermal conductivity of the matrix is analyzed by the void/matrix *** prediction results at the mesoscale correspond closely to the experimental *** effect of the porosities and fiber volume fractions on the thermal conductivities is also taken into *** multi-scale models mentioned in this paper can be used to predict the thermal conductivity behaviors of other composites with complex structures.

关键词： 3D C/SiC composites Finite element analyses Multi-scale modeling Thermal conductivity

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Morphogenesis and Molecular Phylogeny of a Marine Urostylid Ciliate Apokeronopsis wrighti(Protista, Ciliophora, Hypotrichia)

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Journal of Ocean University of china 2024年第4期23卷 1067-1075页

作者： LIAN Chunyu LI Ping ZHANG Tengteng SHAO Chen Department of Zoology College of Life SciencesShaanxi Normal UniversityXi’an 710119China Powerchina Northwest Engineering corporation limited Xi’an 710065China

Hypotrichs are one of the highly differentiated ciliated lineages which play important roles in ecological, environmental,evolutionary and basic biological studies. In the present study, we investigated the living characteristics, infraciliature, nuclear apparatus, ontogenesis and phylogenetic position of a marine hypotrichous ciliate, Apokeronopsis wrighti Long et al., 2008, which was isolated from coastal waters in Shenzhen, china. The new isolate resembles the type population in terms of morphological characteristics, morphometrics, and SSU rRNA gene sequence that is with a 99.7% similarity. Ontogenesis of A. wrighti is characterized by oral primordium for the proter as well as marginal and dorsal kineties anlagen in both filial products formed de novo, and the cirral row arranged along the paroral and endoral arises from several anterior frontoventral-transverse cirral streaks. Phylogenetic analyses based on SSU and concatenated gene data suggest that five species of Apokeronopsis form a monophyletic clade, and the genus Apokeronopsis is closely related to Thigmokeronopsis and Metaurostylopsis.

关键词： 18S rRNA gene Apokeronopsis ciliated protists multi-gene ontogenesis systematics Urostylida

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Experimental study of the effects of a multistage pore-throat structure on the seepage characteristics of sandstones in the Beibuwan Basin:Insights into the flooding mode

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Petroleum Science 2024年第2期21卷 1044-1061页

作者： Lei Wang Xiao Lei Qiao-Liang Zhang Guang-Qing Yao Bo Sui Xiao-Jun Chen Ming-Wei Wang Zhen-Yu Zhou Pan-Rong Wang Xiao-Dong Peng Zhanjiang Branch China National Offshore Oil Corporation(CNOOC)LimitedZhanjiang524057GuangdongChina Faculty of Earth Resources China University of Geosciences(Wuhan)Wuhan430074HubeiChina School of Resources and Safety Engineering Chongqing UniversityChongqing400044China School of Engineering University of ManchesterManchester M139WJUK Hainan Branch China National Offshore Oil Corporation(CNOOC)LimitedHaikou570311HainanChina

To investigate the relationship between grain sizes, seepage capacity, and oil-displacement efficiency in the Liushagang Formation of the Beibuwan Basin, this study identifies the multistage pore-throat structure as a crucial factor through a comparison of oil displacement in microscopic pore-throat experiments. The two-phase flow evaluation method based on the Li-Horne model is utilized to effectively characterize and quantify the seepage characteristics of different reservoirs, closely relating them to the distribution of microscopic pores and throats. It is observed that conglomerate sandstones at different stages exhibit significant heterogeneity and noticeable differences in seepage capacity, highlighting the crucial role played by certain large pore throats in determining seepage capacity and oil displacement efficiency. Furthermore, it was found that the displacement effects of conglomeratic sandstones with strong heterogeneity were inferior to those of conventional homogeneous sandstone, as evidenced by multiple displacement experiments conducted on core samples with varying granularities and flooding systems. Subsequently, core-based experiments on associated gas flooding after water flooding were conducted to address the challenge of achieving satisfactory results in a single displacement mode for reservoirs with significant heterogeneity. The results indicate that the oil recovery rates for associated gas flooding after water flooding increased by 7.3%-16.4% compared with water flooding alone at a gas-oil ratio of approximately 7000 m^(3)/m^(3). Therefore, considering the advantages of gas flooding in terms of seepage capacity, oil exchange ratio, and the potential for two-phase production, gas flooding is recommended as an energy supplement mode for homogeneous reservoirs in the presence of sufficient gas source and appropriate tectonic angle. On the other hand, associated gas flooding after water flooding is suggested to achieve a more favorable develop

关键词： Beibuwan Basin Multistage pore-throat structure Multistage seepage characteristics Microscopic visualization Heterogeneity Gas/water flooding Flooding mode

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