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Visualization and characterization of experimental hydraulic fractures interacting with karst fracture-cavity distributions

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1667-1683页

作者： Hanzhi Yang Xin Chang Chunhe Yang Wuhao guo lei Wang guokai Zhao Yintong guo State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400044China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

Karst fracture-cavity carbonate reservoirs,in which natural cavities are connected by natural fractures to form cavity clusters in many circumstances,have become significant fields of oil and gas exploration and *** fracturing is considered as the best method for exploiting carbonate reservoirs;however,previous studies primarily focused on the effects of individual types of geological formations,such as natural fractures or cavities,on fracture *** this study,true-triaxial physical simulation experiments were systematically performed under four types of stress difference conditions after the accurate prefabrication of four types of different fracture-cavity distributions in artificial ***,the interaction mechanism between the hydraulic fractures and fracture-cavity structures was systematically analyzed in combination with the stress distribution,cross-sectional morphology of the main propagation path,and three-dimensional visualization of the overall fracture *** was found that the propagation of hydraulic fractures near the cavity was inhibited by the stress concentration surrounding the *** contrast,a natural fracture with a smaller approach angle(0°and 30°)around the cavity can alleviate the stress concentration and significantly facilitate the connection with the *** addition,the hydraulic fracture crossed the natural fracture at the 45°approach angle and bypassed the cavity under higher stress difference conditions.A new stimulation effectiveness evaluation index was established based on the stimulated reservoir area(SRA),tortuosity of the hydraulic fractures(T),and connectivity index(CI)of the *** findings provide new insights into the fracturing design of carbonate reservoirs.

关键词： Karst fracture-cavity reservoir Fracturing experiment Fracture propagation Cross-sectional morphology Stimulation effectiveness

Exploiting sound for emerging applications of extracellular vesicles

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Nano Research 2024年第2期17卷 462-475页

作者： Zhuhao Wu Hongwei Cai Chunhui Tian Zheng Ao lei Jiang Feng guo Department of Intelligent Systems Engineering Indiana UniversityBloomingtonIN 47405USA

Extracellular vesicles are nano-to micro-scale,membrane-bound particles released by cells into extracellular space,and act as carriers of biomarkers and therapeutics,holding promising potential in translational ***,the challenges remain in handling and detecting extracellular vesicles for disease diagnosis as well as exploring their therapeutic capability for disease ***,we review the recent engineering and technology advances by leveraging the power of sound waves to address the challenges in diagnostic and therapeutic applications of extracellular vesicles and biomimetic *** first introduce the fundamental principles of sound waves for understanding different acoustic-assisted extracellular vesicle *** discuss the acoustic-assisted diagnostic methods including the purification,manipulation,biosensing,and bioimaging of extracellular ***,we summarize the recent advances in acoustically enhanced therapeutics using extracellular vesicles and biomimetic ***,we provide perspectives into current challenges and future clinical applications of the promising extracellular vesicles and biomimetic nanovesicles powered by sound.

关键词： extracellular vesicles exosomes biomimetic nanovesicles acoustics disease diagnostics therapeutics

Roof collapse mechanism of weak surrounding rock for deep-buried tunnels under high geostress conditions

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Journal of Mountain Science 2024年第7期21卷 2408-2426页

作者： ZHANG Qi guo Xiaokang YAN Zhiguo lei Zhongdai SHEN Yixin School of Civil Engineering Southeast UniversityNanjing 211189China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

High geostress,a typical attribute of tunnels located at significant depths,is crucial in causing stress-induced failure and influencing the stability of the tunnel *** study developed an analytical method for the failure mechanism that occurs in deep-buried tunnel roofs,taking into account the influence of *** limit analysis theory was utilized for deriving analytical solutions about the geometry of the collapsing surface and the limit supporting *** collapsing surface obtained by the analytical solution was validated by the findings of the physical model test,which shows a high level of agreement with the actual *** extensive investigation was done to explore the effects of the lateral pressure coefficients,the tunnel buried depth,the geological conditions of the surrounding rock,the long-short axis ratio,and the size of the tunnel *** findings indicate that an increase in the lateral pressure coefficient from 0.5 to 1.5 results in a reduction in the height of the collapsing zone by 2.08 m and the width of the collapsing zone by 1.15 m,while simultaneously increases the limit supporting pressure by 18.9%.The proposed upper bound method accurately determines the limit supporting pressure and the geometry of the collapsing surface,which aligns well with the results acquired through numerical modelling and on-site monitoring in actual engineering *** proposed analytical method can serve as a reference for similar crown failure issues of deep-buried tunnels.

关键词： Geostress Deep-buried tunnels Collapse mechanism Pressure arch Limit analysis HoekBrown criterion

Joint computation offloading and parallel scheduling to maximize delay-guarantee in cooperative MEC systems

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Digital Communications and Networks 2024年第3期10卷 693-705页

作者： Mian guo Mithun Mukherjee Jaime Lloret lei Li Quansheng Guan Fei Ji School of Electronics and Information Guangdong Polytechnic Normal UniversityGuangzhouChina School of Artificial Intelligence Nanjing University of Information Science and TechnologyNanjingChina Universitat Politecnica de Valencia 46022ValenciaSpain South China University of Technology China

The growing development of the Internet of Things(IoT)is accelerating the emergence and growth of new IoT services and applications,which will result in massive amounts of data being generated,transmitted and pro-cessed in wireless communication *** Edge Computing(MEC)is a desired paradigm to timely process the data from IoT for value *** MEC,a number of computing-capable devices are deployed at the network edge near data sources to support edge computing,such that the long network transmission delay in cloud computing paradigm could be *** an edge device might not always have sufficient resources to process the massive amount of data,computation offloading is significantly important considering the coop-eration among edge ***,the dynamic traffic characteristics and heterogeneous computing capa-bilities of edge devices challenge the *** addition,different scheduling schemes might provide different computation delays to the offloaded ***,offloading in mobile nodes and scheduling in the MEC server are coupled to determine service *** paper seeks to guarantee low delay for computation intensive applica-tions by jointly optimizing the offloading and scheduling in such an MEC *** propose a Delay-Greedy Computation Offloading(DGCO)algorithm to make offloading decisions for new tasks in distributed computing-enabled mobile devices.A Reinforcement Learning-based Parallel Scheduling(RLPS)algorithm is further designed to schedule offloaded tasks in the multi-core MEC *** an offloading delay broadcast mechanism,the DGCO and RLPS cooperate to achieve the goal of delay-guarantee-ratio ***,the simulation results show that our proposal can bound the end-to-end delay of various *** under slightly heavy task load,the delay-guarantee-ratio given by DGCO-RLPS can still approximate 95%,while that given by benchmarked algorithms is reduced to intolerable *** simulation resul

关键词： Edge computing Computation offloading Parallel scheduling Mobile-edge cooperation Delay guarantee

Hollow Metal-Organic Framework/MXene/Nanocellulose Composite Films for Giga/Terahertz Electromagnetic Shielding and Photothermal Conversion

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Nano-Micro Letters 2024年第9期16卷 161-179页

作者： Tian Mai lei Chen Pei‑Lin Wang Qi Liu Ming‑guo Ma Research Center of Biomass Clean Utilization MOE Engineering Research Center of Forestry Biomass Materials and BioenergyBeijing Key Laboratory of Lignocellulosic ChemistryCollege of Materials Science and TechnologyBeijing Forestry UniversityBeijing 100083People’s Republic of China State Silica-Based Materials Laboratory of Anhui Province Bengbu 233000People’s Republic of China

With the continuous advancement of communication technology,the escalating demand for electromagnetic shielding interference(EMI)materials with multifunctional and wideband EMI performance has become *** the electrical and magnetic components and designing the EMI material structure have attracted extensive interest,but remain a huge ***,we reported the alternating electromagnetic structure composite films composed of hollow metal-organic frameworks/layered MXene/nanocellulose(HMN)by alternating vacuum-assisted filtration *** HMN composite films exhibit excellent EMI shielding effectiveness performance in the GHz frequency(66.8 dB at Kaband)and THz frequency(114.6 dB at 0.1-4.0 THz).Besides,the HMN composite films also exhibit a high reflection loss of 39.7 dB at 0.7 THz with an effective absorption bandwidth up to 2.1 ***,HMN composite films show remarkable photothermal conversion performance,which can reach 104.6℃under 2.0 Sun and 235.4℃under 0.8 W cm^(−2),*** unique micro-and macrostructural design structures will absorb more incident electromagnetic waves via interfacial polarization/multiple scattering and produce more heat energy via the local surface plasmon resonance *** features make the HMN composite film a promising candidate for advanced EMI devices for future 6G communication and the protection of electronic equipment in cold environments.

关键词： Metal-organic frameworks MXene Nanocellulose Electromagnetic shielding Photothermal conversion

A survey on semantic communications:Technologies,solutions,applications and challenges

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Digital Communications and Networks 2024年第3期10卷 528-545页

作者： Yating Liu Xiaojie Wang Zhaolong Ning MengChu Zhou lei guo Behrouz Jedari School of Communication and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing 400065China Baotou Vocational&Technical College Baotou 014035China School of Information and Electronic Engineering Zhejiang Gongshang UniversityHangzhou 310018China Department of Electrical and Computer Engineering New Jersey Institute of TechnologyNewarkNJ 07102USA Nokia Finland

Semantic Communication(SC)has emerged as a novel communication paradigm that provides a receiver with meaningful information extracted from the source to maximize information transmission throughput in wireless networks,beyond the theoretical capacity *** the extensive research on SC,there is a lack of comprehensive survey on technologies,solutions,applications,and challenges for *** this article,the development of SC is first reviewed and its characteristics,architecture,and advantages are ***,key technologies such as semantic extraction,semantic encoding,and semantic segmentation are discussed and their corresponding solutions in terms of efficiency,robustness,adaptability,and reliability are *** of SC to UAV communication,remote image sensing and fusion,intelligent transportation,and healthcare are also presented and their strategies are ***,some challenges and future research directions are presented to provide guidance for further research of SC.

关键词： Semantic communication Semantic coding Semantic extraction Semantic communication framework Semantic communication applications

Fracture mechanism of inclusions in thick plate center under tensile loading

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Journal of Iron and Steel Research International 2024年第5期31卷 1196-1209页

作者： lei Hu Li-qin Zhang Feng Hu guo-hong Zhang Kuan Zheng Collaborative Innovation Center for Advanced Steels Wuhan University of Science and TechnologyWuhan430081HubeiChina Department of Applied Physics Wuhan University of Science and TechnologyWuhan430081HubeiChina Analysis and Testing Center Wuhan University of Science and TechnologyWuhan430081HubeiChina

Segregation of solute atoms in the center of thick plates of the tempered steel can cause an inhomogeneous structural transformation and generate micron-sized inclusions,which leads to lamellar tearing of thick plate and decreases the plasticity and *** formation and fragmentation mechanisms of micron-sized inclusions,like MnS and(Nb,Ti)C,in the center of thick plates were investigated by using thermodynamic calculations,finite element simulations,and electron backscatter diffraction characterization *** results show that micron-sized inclusions nucleate and grow in the liquid phase,and under tensile loading,they exhibit three fragmentation *** local stress during the fragmentation of inclusions is lower than the critical fracture stress of adjacent grains,and phase boundaries can effectively impede crack propagation into the *** existence of a low proportion of high-angle grain boundaries(58.1%)and high Kernel average misorientation value(0.534°)in the segregation band promotes inclusions fragmentation and crack *** difference in crack initiation and propagation direction caused by the morphology of inclusions and physical properties,as well as different matrix arrest abilities,is the main reasons for the diversity of inclusion fragmentation.

关键词： Thick plate Inclusion Finite element simulation Critical fracture stress Fracture mechanism

Potential evaluation and implementation strategy for pocket park construction in high-density urban areas: A case study in Dalian, China

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Frontiers of Architectural Research 2024年第2期13卷 319-334页

作者： Jing dong Ruonan guo Fei guo Jun Cai School of Architecture and Fine Art Dalian University of TechnologyDalian 116024China

As an important element of urban renewal in highly urbanized areas, pocket parks with small size, flexible layout and daily accessibility are becoming a major component of green infrastructure and the mainstay of outdoor recreation space expansion in high-density urban centers. Nevertheless, the absence of a comprehensive framework for evaluating the potential of pocket park construction (PPC), one that integrates diverse influencing factors on a macro scale, has resulted in the random installation of such spaces, often failing to optimize the utilization of urban land. Addressing this critical lacuna, we propose an approach to evaluate PPC potential from a city-scale perspective, which is used to support the determination of which land units should be prioritized for PPC. A complete and feasible workflow was also established to identify potential land units, construct an index system for PPC combining demand and supply levels, quantitatively calculate indices based on remote sensing (RS) and geographic information system (GIS), accurately evaluate PPC potential using an entropy-weighted TOPSIS model, and develop targeted renewal strategies. A case study in Dalian, China, demonstrated the applicability and implications of the workflow. The results showed that it is flexible and easy to adapt to different local contexts, allowing evaluators to introduce parameters considering the availability of local data, and will help decision makers to build pocket parks in the most effective plots, providing a strong reference for high-quality development in other high-density urban centers facing the contradiction between ecological construction and land scarcity.

关键词： Pocket park Potential evaluation Urban renewal High-density urban areas

Effects of dimethyl ether and ethanol additions on soot transition in ethylene counterflow diffusion flames

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Science China(Technological Sciences) 2024年第4期67卷 1094-1112页

作者： guo LinGe YING YaoYao CHEN Chen ZHAO Xuan LIU dong MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China Advanced Combustion Laboratory School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China

This paper investigates the effect of blending dimethyl ether(DME)and ethanol on the soot transition periods in ethylene counterflow diffusion flames by using a novel optical diagnostic *** soot critical transition point in different conditions is identified experimentally and *** kinds of flames are carried out to gain the soot critical transition point in counterflow diffusion flames by changing oxygen fraction(Xo)and changing volume flow rates of fuel and oxidizer(Qv).The red-green-blue(RGB)ratio method is used to precisely identify the soot critical transition point,and chemical kinetic simulations are performed to analyze the detailed reaction *** results show that compared to the ethylene flame,the soot critical transition point occurs at a higher Xoand a lower Qvwhen DME or ethanol is *** addition of DME and ethanol can inhibit soot formation,due to the degree of soot formation reaction being lower than the degree of the oxidation reaction in the blending flames.

关键词： optical diagnosis sooting tendency counterflow diffusion flame dimethyl ether ethanol