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High-Temperature and Low-Frequency Acoustic Energy Absorption by a Novel Porous Metamaterial Structure

Acta Mechanica Solida Sinica 2021年第6期34卷 872-883页

作者： Qihang liu xuewei liu Chuanzeng Zhang Fengxian Xin Department of Civil Engineering University of SiegenSiegen57076Germany State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an710049China

In this paper,we propose a novel porous metamaterial structure with an improved acoustic energy absorption performance at high-temperature and in the low-frequency *** the proposed novel porous metamaterial structure,a porous material matrix containing periodically perforated cylindrical holes arranged in a triangular lattice pattern is applied,and additional interlayers of another porous material are introduced around these *** theoretical model is established by adopting the double porosity theory for the interlayer and the cylindrical hole which form an equivalent inclusion and then applying the homogenization method to the porous metamaterial structure formed by the equivalent inclusion and the porous *** temperature-dependent air and material parameters are considered in the extended theoretical model,which is validated by the finite element results obtained by COMSOL *** acoustic or sound energy absorption performance can be improved remarkably at very low frequencies and high ***,the underlying acoustic energy absorption mechanism inside the unit-cell is investigated by analyzing the distribution of the time-averaged acoustic power dissipation density and the energy dissipation ratio of each constituent porous *** results reveal that regardless of the temperature,the acoustic energy is mostly dissipated in the porous material with a lower airflow resistivity,while the acoustic energy dissipated in the porous material with a higher airflow resistivity also becomes considerable in the high-frequency *** novel porous metamaterial structure proposed in this paper can be efficiently utilized to improve the acoustic energy absorption performance at high temperature.

关键词： Novel porous metamaterial structure Double porosity theory Homogenization method Acoustic or sound energy absorption High temperature

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Effects of seepage pressure on the mechanical behaviors and microstructure of sandstone

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2033-2051页

作者： xuewei liu Juxiang Chen Bin liu Sai Wang Quansheng liu Jin Luo State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Faculty of Engineering China University of GeosciencesWuhan430074China Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province School of Civil EngineeringWuhan UniversityWuhan430072China

Surrounding rocks of underground engineering are subjected to long-term seepage pressure,which can deteriorate the mechanical properties and cause serious *** order to understand the impact of seepage pressure on the mechanical property of sandstone,uniaxial compression tests,P-wave velocity measurements,and nuclear magnetic resonance(NMR)tests were conducted on saturated sandstone samples with varied seepage pressures(i.e.0 MPa,3 MPa,4 MPa,5 MPa,6 MPa,7 MPa).The results demonstrate that the mechanical parameters(uniaxial compressive strength,peak strain,elastic modulus,and brittleness index),total energy,elastic strain energy,as well as elastic strain energy ratio,decrease with increasing seepage pressure,while the dissipation energy and dissipation energy ratio ***,as seepage pressure increases,the micro-pores gradually transform into meso-pores and *** increases the cumulative porosity of sandstone and decreases P-wave *** numerical results indicate that as seepage pressure rises,the number of tensile cracks increases progressively,the angle range of microcracks is basically from 50-120to 80-100,and as a result,the failure mode transforms to the tensile-shear mixed failure ***,the effects of seepage pressure on mechanical properties were *** results show that decrease in the effective stress and cohesion under the action of seepage pressure could lead to deterioration of strength behaviors of sandstone.

关键词： Rock mechanics Mechanical property Seepage pressure Numerical simulation Microcracks

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Gentianine protects hippocampal neurons in a rat model of recurrent febrile convulsion

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Neural Regeneration Research 2011年第15期6卷 1130-1135页

作者： xuewei liu Shumin liu Na Wang Fang Lu Min Cao Academy of Traditional Medicine Heilongjiang University of Traditional Chinese Medicine Harbin 150040 Heilongjiang Province China Postgraduate Department of Heilongjiang University of Traditional Chinese Medicine Harbin 150040 Heilongjiang Province China

Gentianine has been shown to have a protective effect on hippocampal CA1 neurons in rats subjected to recurrent febrile convulsion（FC）.The present study sought to explore the possible mechanism of gentianine by intraperitoneally injecting gentianine into rats with warm water-induced *** results revealed that neuronal organelle injury was slightly ameliorated in the hippocampal CA1 *** level of glutamate was decreased,but the level of γ-aminobutyric acid was increased,as detected by ninhydrin *** addition,glutamate acid decarboxylase expression in hippocampal CA1 was increased,as determined by *** results demonstrated that gentianine can ameliorate FC-induced neuronal injury by enhancing glutamate acid decarboxylase activity,decreasing glutamate levels and increasing γ-aminobutyric acid levels.

关键词： febrile convulsion gentianine hippocampal neurons neuroprotective effect glutamate γ-aminobutyric acid neural regeneration

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A real-time prediction method for tunnel boring machine cutter-head torque using bidirectional long short-term memory networks optimized by multi-algorithm

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第3期14卷 798-812页

作者： Xing Huang Quantai Zhang Quansheng liu xuewei liu Bin liu Junjie Wang Xin Yin State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Key Laboratory of Geotechnical and Structural Engineering Safety of Hubei Province School of Civil EngineeringWuhan UniversityWuhan430072China The 2nd Engineering Company of China Railway 12th Bureau Group Taiyuan030032China

Based on data from the Jilin Water Diversion Tunnels from the Songhua River(China),an improved and real-time prediction method optimized by multi-algorithm for tunnel boring machine(TBM)cutter-head torque is ***,a function excluding invalid and abnormal data is established to distinguish TBM operating state,and a feature selection method based on the SelectKBest algorithm is ***,ten features that are most closely related to the cutter-head torque are selected as input variables,which,in descending order of influence,include the sum of motor torque,cutter-head power,sum of motor power,sum of motor current,advance rate,cutter-head pressure,total thrust force,penetration rate,cutter-head rotational velocity,and field penetration ***,a real-time cutterhead torque prediction model’s structure is developed,based on the bidirectional long short-term memory(BLSTM)network integrating the dropout algorithm to prevent ***,an algorithm to optimize hyperparameters of model based on Bayesian and cross-validation is *** stopping and checkpoint algorithms are integrated to optimize the training ***,a BLSTMbased real-time cutter-head torque prediction model is developed,which fully utilizes the previous time-series tunneling *** mean absolute percentage error(MAPE)of the model in the verification section is 7.3%,implying that the presented model is suitable for real-time cutter-head torque ***,an incremental learning method based on the above base model is introduced to improve the adaptability of the model during the TBM *** of the prediction performance between the base and incremental learning models in the same tunneling section shows that:(1)the MAPE of the predicted results of the BLSTM-based real-time cutter-head torque prediction model remains below 10%,and both the coefficient of determination(R^(2))and correlation coefficient(r)between measured and

关键词： Tunnel boring machine(TBM) Real-time cutter-head torque prediction Bidirectional long short-term memory (BLSTM) Bayesian optimization Multi-algorithm fusion optimization Incremental learning

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Experimental and numerical investigation on failure characteristics and mechanism of coal with different water contents

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International Journal of Coal Science & Technology 2023年第4期10卷 325-342页

作者： xuewei liu Haixiao Chen Bin liu Sai Wang Quansheng liu Yong Luo Jin Luo State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China Faculty of Engineering China University of GeosciencesWuhan 430074China Ping’an Mining Engineering Technology Research Institute Co. Ltd.Huainan 232001China

Water injection, as a widely used technique to prevent coal burst, can restrain the fractured coal seam and released the energy storage. In this study, laboratory tests were frstly carried out on standard coal specimens with fve diferent water contents (i.e., 0%, 0.6%, 1.08%, 1.5%, 2.0%, and 2.3%). The failure mode, fragment size, and energy distribution characteristics of coal specimens were investigated. Experimental results show that strength, elastic strain energy, dissipated energy, brittleness index, as well as impact energy index decrease with increasing water content. Besides, the failure mode transitions gradually from splitting ejection to tensile-shear mixed failure mode as water content increases, and average fragment size shows positively related to water content. Moreover, scanning electron microscope tests results indicate that water in coal sample mainly causes the mineral softening and defects increase. Furthermore, a numerical model containing roadway excavation was established considering the water on coal burst prevention. Modelling results revealed that water injection can reduce degree of coal burst and ejection velocity of coal blocks, while it will raise up the depth of crack zone and surface displacement of roadway. Combined with laboratory tests and numerical results, the micro mechanism, energy mechanism, and engineering signifcance of water injection on coal burst prevention were fnally analyzed.

关键词： Water content Coal burst Failure mode Energy Numerical simulation

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Further studies on the numerical simulation of bubble plumes in the cold seepage active region

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Acta Oceanologica Sinica 2016年第1期35卷 118-124页

作者： LI Canping GOU Limin YOU Jiachun liu xuewei OU Chuling Guangdong Province Key Laboratory for Coastal Ocean Variation and Disaster Prediction (GLOD) Guangdong Ocean University Laboratory of Ocean Remote Sensing and Information Technology Guangdong Ocean University School of Ocean Sciences China University of Geosciences (Beijing) School of Geophysics and Information Technology China University of Geosciences (Beijing)

Using the occurrence characteristics of bubble plumes in the South China Sea as a reference, this paper continues to study the seismic responses produced by bubble plumes in the cold seepage active region. To make the plume modelling scheme more reasonable, we modified the original modelling scheme and reconstructed a plume water body model based on the variation of its radius as bubbles rise in seawater. The plume seismic records of shot gathers were obtained by forward simulation. The seismic records of single shot show obvious characteristics of a scattering wave field and the periodic characteristics of the model. Seismic records of shot gathers were processed using prestack depth migration. The boundary of its imaging section has a good convergence effect. The migration sections can be imaged distinctly with higher accuracy. The aforementioned studies once again laid a foundation for the further study of the seismic responses produced by plumes. They also gradually probed a more suitable seismic data processing method for plumes and provided a theoretical guidance for the identification of plumes.

关键词： plume cold seepage gas hydrate scattered wave numerical simulation

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Isolation of Immune-Relating 185/333-1 Gene from Sea Urchin(Strongylocentrotus intermedius) and Its Expression Analysis

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Journal of Ocean University of China 2016年第1期15卷 163-170页

作者： WANG Yinan DING Jun liu Yang liu xuewei CHANG Yaqing Key Laboratory of Mariculture & Stock Enhancement in North China Sea Ministry of AgricultureDalian Ocean University

The 185/333 gene family involved in the immune response of sea *** 185/333 c DNA was isolated from Strongylocentrotus intermedius,and named as Si185/*** full-length c DNA was 1246 bp in length with a 906 bp open reading frame encoding a protein of 301 *** molecular weight of the deduced protein was approximately 33.1 k D with an estimated PI of p H ***185/333-1 had high identities(70%–86%) to most of Sp185/*** extraordinary identity of 92% was found between Si185/333-1 and Sp185/333 C5 alpha(ABR22474).Moderate identities(63%–64%) were displayed between Si185/333-1 and He185/***185/333-1 had similar structure to Sp185/333.A signal-peptide,a gly-rich region and a his-rich region were found in its secondary *** motif was found in gly-rich region at position 116–*** was no transmembrane region in Si185/*** element pattern of Si185/333-1 is different from any available pattern that identified in Sp185/***185/333-1 clustered together with pattern C Sp185/333 in phylogenetic *** Si185/333-1 m RNA could be detected in tissues including peristomial membrane,coelomocytes,muscle of Aristotles lantern,gut and tube feet,with the highest expression level detected in peristomial membrane and a relatively low expression in ovary and *** temporal expression of Si185/333-1 in peristomial membrane and coelomocytes were up-regulated after bacterial,β-D-glucan and ds RNA challenges,reaching the maximum at 12 h *** up-regulation was more obvious in coelomocytes,and bacterial challenge triggered the highest *** results proved that 185/333-1 gene was involved in the immune defense of ***,while more studies were necessary for its function in *** immunity.

关键词： sea urchin Strongylocentrotus intermedius 185/333 immune

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Numerical Simulation of Slurry Diffusion in Fractured Rocks Considering a Time-Varying Viscosity

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Fluid Dynamics & Materials Processing 2024年第2期20卷 401-427页

作者： Lei Zhu Bin liu xuewei liu Wei Deng Wenjie Yao Ying Fan School of Civil Engineering Architecture and EnvironmentHubei University of TechnologyWuhan430068China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

To analyze the effects of a time-varying viscosity on the penetration length of grouting,in this study cement slur-ries with varying water-cement ratios have been investigated using the Bingham’sﬂuidﬂow equation and a dis-crete element method.Aﬂuid-solid coupling numerical model has been introduced accordingly,and its accuracy has been validated through comparison of theoretical and numerical *** different fracture forms(a single fracture,a branch fracture,and a fracture network),the inﬂuence of the time-varying viscosity on the slurry length range has been investigated,considering the change in the fracture *** results show that under different fracture forms and the same grouting process conditions,the inﬂuence of the time-varying viscosity on the seepage length is 0.350 m.

关键词： Time-varying viscosity binghamﬂuids UDEC numerical simulation grout penetration length aperture

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On the Development of an Effective Pressure Driving System for Ultra-Low Permeability Reservoirs

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Fluid Dynamics & Materials Processing 2021年第6期17卷 1067-1075页

作者： Yapu Zhang Zhengming Yang Dajian Li xuewei liu Xinli Zhao Research Institute of Petroleum Exploration&Development PetroChinaBeijing100083China College of Engineering Science University of Chinese Academy of SciencesBeijing100049China Oil and Gas Technology Research Institute of PetroChina Changqing Oilfield Company Xi’an070000China

Given its relevance to the exploitation of ultra-low permeability reservoirs,which account for a substantial proportion of the world’s exploited and still unexploited reserves,in the present study the development of an adequate water injection system is *** to the poor properties and weak seepage capacity of these reservoirs,the water injection pressure typically increases continuously during water *** this research,the impact on such a process of factors as permeability,row spacing,and pressure gradient is evaluated experimentally using a high-pressure large-scale outcrop *** this basis,a comprehensive evaluation coefficient is introduced able to account for the effective driving pressure.

关键词： Ultra-low permeability reservoir physical simulation effective development water flooding effective driving coefficient

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Sound absorption performance of gradiently slit-perforated double-porosity materials

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Chinese Journal of Acoustics 2021年第1期40卷 1-17页

作者： MA Xiaowen liu xuewei XIN Fengxian State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an 710049 MOE Key Laboratory for Multifunctional Materials and Structures Xi'an Jiaotong UniversityXi’an 710049

A gradiently slit-perforated double-porosity material is proposed by introducing macro-scale periodic gradient slit-perforations into traditional porous materials with *** material is one kind of multiscale material since it includes two scales of matrix micro-pore size and slit-perforation size.A theoretical model is developed for the sound absorption of the gradiently slit-perforated double-porosity *** the model,the material is divided into lots of thin layers and each layer is approximated to be straight slit-perforated *** equivalent density and dynamic compressibility of each thin layer are given by using the low or high permeability contrast double-porosity *** the sound pressure and particle velocity relations between adjacent thin layers are obtained by employing the transfer matrix ***,the surface acoustic impedance and the sound absorption of the gradiently slit-perforated porous material can be calculated.A finite element model is further established to validate the accuracy of the theoretical *** the considered frequency range of 100-3000 Hz,the simulation results agree well with theoretical *** influence of multiscale structural parameters on the sound absorption performance of the porous materials is analyzed theoretically and *** is proved that the multiscale structure design can significantly improve the sound absorption performance of porous *** to the slit-perforation gradient,the slit-perforation width plays a more significant influence on sound *** sound absorption enhancement mechanism of the multiscale structure design is revealed by the analysis of the sound pressure and energy dissipation distributions in the *** work provides a multiscale structural design method for improving the sound absorption performance of traditional porous materials at broadband frequency.

关键词： absorption gradient perforated

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