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Shear band evolution and acoustic emission characteristics of sandstone containing non-persistent flaws

Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 497-513页

作者： Shuting Miao Peng-Zhi pan Chuanqing Zhang Lei Huo State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China CASIC Research Institute of Intelligent Decision Engineering Wuhan430040China

Direct shear tests were conducted on sandstone specimens under different constant normal stresses to study the coalescence of cracks between non-persistent flaws and the shear sliding characteristics of the shear-formed *** image correlation and acoustic emission(AE)techniques were used to monitor the evolution of shear bands at the rock bridge area and microcracking *** experimental results revealed that the shear stresses corresponding to the peak and sub-peak in the stressdisplacement curve are significantly affected by the normal *** localization bands emerged at both the tip of joints and the rock bridge,and their extension and interaction near the peak stress caused a surge in the AE hit rate and a significant decrease in the AE b *** and curvilinear strain bands were detected at low normal stress,while high normal stress generally led to more microcracking events and longer coplanar cracks at the rock bridge ***,an increase in normal stress resulted in a higher AE count rate and more energetic AE events during friction sliding along the shearformed *** was observed that the elastic energy released during the crack coalescence at the prepeak stage was much greater than that released during friction sliding at the post-peak *** than 75%of AE events were located in the low-frequency band(0e100 kHz),and this proportion continued to rise with increasing normal ***,more AE events of low AF value and high RA value were observed in specimens subjected to high normal stress,indicating that greater normal stress led to more microcracks of shear nature.

关键词： Shear band evolution Acoustic emission(AE) Crack coalescence Normal stress Shear sliding

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Molecular Generation and Optimization of Molecular Properties Using a Transformer Model

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Big Data Mining and Analytics 2024年第1期7卷 142-155页

作者： Zhongyin Xu Xiujuan Lei Mei Ma Yi pan School of Computer Science Shaanxi Normal UniversityXi'an 710119China Faculty of Computer Science and Control Engineering Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Generating novel molecules to satisfy specific properties is a challenging task in modern drug discovery,which requires the optimization of a specific objective based on satisfying chemical ***,we aim to optimize the properties of a specific molecule to satisfy the specific properties of the generated *** Matched Molecular Pairs(MMPs),which contain the source and target molecules,are used herein,and logD and solubility are selected as the optimization *** main innovative work lies in the calculation related to a specific transformer from the perspective of a matrix *** intervals and state changes are then used to encode logD and solubility for subsequent *** the experiments,we screen the data based on the proportion of heavy atoms to all atoms in the groups and select 12365,1503,and 1570 MMPs as the training,validation,and test sets,*** models are compared with the baseline models with respect to their abilities to generate molecules with specific *** show that the transformer model can accurately optimize the source molecules to satisfy specific properties.

关键词： molecular optimization transformer Matched Molecular Pairs(MMPs) logD solubility

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Effect of Wave Nonlinearity on the Instantaneous Seabed Liquefaction

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China Ocean Engineering 2024年第1期38卷 93-103页

作者： WANG Zhao-jun SUI Ti-ti ZHANG Chi pan Jun-ning Key Laboratory of Port Waterway and Sedimentation Engineering of the Ministry of TransportNanjing Hydraulic Research InstituteNanjing 210024China Key Laboratory of Coastal Disaster and Protection(Hohai University) Ministry of EducationNanjing 210098China The National Key Laboratory of Water Disaster Prevention Nanjing 210098China

The nonlinear variation of wave is commonly seen in nearshore area,and the resulting seabed response and liquefaction are of high concern to coastal *** this study,an analytical formula considering the nonlinear wave skewness and asymmetry is adopted to provide wave pressure on the seabed *** liquefaction depth attenuation coefficient and width growth coefficient are defined to quantitatively characterize the nonlinear effect of wave on seabed *** on the 2D full dynamic model of wave-induced seabed response,a detailed parametric study is carried out in order to evaluate the influence of the nonlinear variation of wave loadings on seabed ***,new empirical prediction formulas are proposed to fast predict the maximum liquefaction under nonlinear *** indicate that(1)Due to the influence of wave nonlinearity,the vertical transmission of negative pore water pressure in the seabed is hindered,and therefore,the amplitude decreases significantly.(2)In general,with the increase of wave nonlinearity,the liquefaction depth of seabed decreases *** under asymmetric and skewed wave loading,the attenuation of maximum seabed liquefaction depth is the most significant among all the nonlinear wave ***,highly skewed wave can cause the liquefaction depth of seabed greater than that under linear wave.(3)The asymmetry of wave pressure leads to the increase of liquefaction width,whereas the influence of skewedness is not significant.(4)Compared with the nonlinear waveform,seabed liquefaction is more sensitive to the variation of nonlinear degree of wave loading.

关键词： nonlinear wave seabed response seabed liquefaction numerical simulation liquefaction prediction

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Co-influence of the start of thermal growing season and precipitation on vegetation spring green-up on the Tibetan Plateau

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Advances in Climate Change Research 2024年第2期15卷 327-337页

作者： Chen-Peng WANG Meng-Tian HUANG pan-Mao ZHAI State Key Laboratory of Severe Weather and Institute of Global Change and Polar Meteorology Chinese Academy of Meteorological SciencesBeijing 100081China University of Chinese Academy of Sciences Beijing 100049China

The climate in the Tibetan Plateau(TP)has undergone significant change in recent decades,mainly in thermal and water conditions,which plays a crucial role in phenological changes in vegetation spring ***,how the start of the thermal growing season(SOS-T)and the start of the rainy season(SORS)as key climatic factors affect vegetation green-up remains *** that these factors characterize thermal and water conditions required for vegetation green-up,this study investigated changes in the SOS-T and SORS from 1961 to 2022,using observation-based datasets with long time *** found that the SOS-T and SORS have advanced across the TP in 1961-2022 and have shown a spatial pattern of advancement in the east and delay in the west in ***,the co-effect of temperature and precipitation change on the start of vegetation growing season(SOS-V)in 2000-2022 was *** across TP,the SOS-V had an early onset of 1.3 d per decade during 2000-2022,corresponding to advanced SOS-T and ***,the SOS-V generally occurred nearly at the same time as the SOS-T in the high-altitude meadow region.A substantial delay in the SOS-V relative to the SOS-T was observed in the desert,shrub,grassland and forest regions and generally kept pace with the ***,for 50%of the vegetated regions on the TP,inter-annual variation in the delay in the SOS-V relative to the SOS-T was dominated by precipitation change,which was profound in warm-climate *** study highlights the co-regulation of precipitation and temperature change in the SOS-V in different vegetation cover regions in the TP,offering a scientific foundation for comprehending the impact of climate change and prospects for vegetation phenology on the TP.

关键词： Tibetan Plateau Start of growing season Temperature Precipitation Climate change

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Unstructured Road Extraction in UAV Images based on Lightweight Model

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 372-384页

作者： Di Zhang Qichao An Xiaoxue Feng Ronghua Liu Jun Han Feng pan School of Automation Beijing Institute of TechnologyBeijing 100081China Tianjin Institute of Maritime Navigation Instruments Tianjin 300130China The 716th Research Institute of China Shipbuilding Group Co. LtdJiangsu 222061China

There is no unified planning standard for unstructured roads,and the morphological structures of these roads are complex and *** is important to maintain a balance between accuracy and speed for unstructured road extraction *** road extraction algorithms based on deep learning have problems such as high model complexity,high computational cost,and the inability to adapt to current edge computing ***,it is best to use lightweight network *** the need for lightweight models and the characteristics of unstructured roads with different pattern shapes,such as blocks and strips,a TMB(Triple Multi-Block)feature extraction module is proposed,and the overall structure of the TMBNet network is *** TMB module was compared with SS-nbt,Non-bottleneck-1D,and other modules via *** feasibility and effectiveness of the TMB module design were proven through experiments and *** comparison experiment,using multiple convolution kernel categories,proved that the TMB module can improve the segmentation accuracy of the *** comparison with different semantic segmentation networks demonstrates that the TMBNet network has advantages in terms of unstructured road extraction.

关键词： Unstructured road Lightweight model Triple Multi-Block(TMB) Semantic segmentation net

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Performance and enhanced oil recovery efficiency of an acid-resistant polymer microspheres of anti-CO2 channeling in low-permeability reservoirs

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Petroleum Science 2024年第4期21卷 2420-2432页

作者： Hai-Zhuang Jiang Hong-Bin Yang Ruo-Sheng pan Zhen-Yu Ren Wan-Li Kang Jun-Yi Zhang Shi-Long pan Bauyrzhan Sarsenbekuly State Key Laboratory of Deep Oil and Gas China University of Petroleum (East China) School of Petroleum Engineering China University of Petroleum (East China) Oil and Gas Engineering Research Institute School of Energy and Petroleum Industry Kazakh-British Technical University

CO2flooding is a vital development method for enhanced oil recovery in low-permeability reservoirs,However,micro-fractures are developed in low-permeability reservoirs,which are essential oil flow channels but can also cause severe CO2gas channeling ***,anti-gas channeling is a necessary measure to improve the effect of *** kind of anti-gas channeling refers to the plugging of fractures in the deep formation to prevent CO2gas channeling,which is different from the wellbore *** microspheres have the characteristics of controllable deep plugging,which can achieve the profile control of low-permeability fractured *** acidic environments with supercritical CO2,traditional polymer microspheres have poor expandability and plugging *** on previous work,a systematic evaluation of the expansion performance,dispersion rheological properties,stability,deep migration,anti-CO2channeling and enhanced oil recovery ability of a novel acid-resistant polymer microsphere（DCNPM-A） was carried out under CQ oilifield conditions（salinity of85,000 mg/L,80℃,pH=3）.The results show that the DCNPM-A microsphere had a better expansion performance than the traditional microsphere,with a swelling rate of *** microsphere dispersion with a concentration of 0.1%-0.5% had the advantages of low viscosity,high dispersion and good injectability in the low permeability fractured *** the acidic environment of supercritical CO2,DCNPM-A microspheres showed excellent stability and could maintain strength for over 60 d with less *** core experiments,DCNPM-A microspheres exhibited delayed swelling characteristics and could effectively plug deep *** a plugging rate of 95%,the subsequent enhanced oil recovery of CO2flooding could reach 21.03%.The experimental results can provide a theoretical basis for anti-CO2channeling and enhanced oil recovery in low-permeability fractured reservoirs.

关键词： Low-permeability reservoir Anti-CO 2 channeling Polymer microsphere Acid resistance

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Experimental and numerical study of hypervelocity impact damage on composite overwrapped pressure vessels

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Defence Technology（防务技术） 2024年第1期31卷 58-72页

作者： Yong-pan Duan Run-Qiang Chi Bao-Jun pang Yuan Cai Hypervelocity Impact Research Center Harbin Institute of TechnologyHarbin150080China College of Science Heilongjiang University of Science and TechnologyHarbin 150022China

Ground-based tests are important for studying hypervelocity impact(HVI)damage to spacecraft pressure vessels in the orbital debris *** analyzed the damage to composite overwrapped pressure vessels(COPVs)in the HVI tests and classified the damage into non-catastrophic damage and catastrophic *** proposed a numerical simulation method to further study non-catastrophic damage and revealed the characteristics and mechanisms of non-catastrophic damage affected by impact conditions and internal *** fragments of the catastrophically damaged COPVs were collected after the *** crack distribution and propagation process of the catastrophic ruptures of the COPVs were *** findings contribute to understanding the damage characteristics and mechanisms of COPVs by HVIs.

关键词： Orbital debris Hypervelocity impact Composite overwrapped pressure vessels Damage mechanisms

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Light demand characteristics,production performance,and changes in the feeding patterns of broilers

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International Journal of Agricultural and Biological Engineering 2024年第2期17卷 68-73页

作者： Shouyi Wang Guoping Jiang Chenghao pan Thebano Santos Yasser Elhadidi Ahmed Jado Shufang Jin Jinming pan College of Biosystems Engineering and Food Science Zhejiang UniversityHangzhou 310058China Infinova(Hangzhou)Information System Technology Co. Ltd.Hangzhou 310012China Center of Information Technology"Renato Archer"(CIT) Ministry of ScienceTechnologyInnovation and CommunicationCEP:13069-901 Campinas(SP)Brazil Department of Agricultural Engineering Mansoura UniversityMansoura 35516Egypt

Poultry is a light-sensitive animal and the light environment has an important influence on the growth and development of these *** studies have mainly focused on the effects of the light environment on various physiological indicators of poultry but seldom explored the light demand characteristics of broilers under free *** experiment mainly studied the light demand characteristics of broilers under a yellow LED light environment and the influence of different breeding densities[low-density(2.5 broilers/m^(2)),high-density(7.5 broilers/m^(2))]on the production performance and diet characteristics of *** showed that the production performance indexes of low-density groups are higher than those of high-density *** feed and water consumption in the light area of the two experimental groups were significantly higher than those in the dark area,which means that the broilers showed a great preference for the light ***,as the age of the broilers increased,the food and water consumption of the broilers decreased,indicating that broilers had a lower preference for light in the middle and late stages of *** statistical results for the residence frequency distribution characteristics showed that broiler chickens had different light requirements at different growth stages under the condition of active selection:1)low-density breeding environment:23.8L(light):0.2D(dark)for chicks and 22.3L:1.7D for adult broilers;2)high-density breeding environment:22.6L:1.4D for chicks and 15.0L:9.0D for adult *** study will provide a reference for the optimization and control of light environment in broiler breeding.

关键词： broiler light-demand characteristics production performance feeding pattern

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A modified stochastic finite-fault method for estimating strong ground motion:Validation and application

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Earthquake Science 2024年第1期37卷 36-50页

作者： Xinjuan He Hua pan Institute of Geophysics China Earthquake AdministrationBeijing 100081China

We developed a modified stochastic finite-fault method for estimating strong ground *** adjustment to the dynamic corner frequency was introduced,which accounted for the effect of the location of the subfault relative to the hypocenter and rupture propagation direction,to account for the influence of the rupture propagation direction on the subfault dynamic corner *** comparing the peak ground acceleration(PGA),pseudo-absolute response spectra acceleration(PSA,damping ratio of 5%),and duration,the results of the modified and existing methods were compared,demonstrating that our proposed adjustment to the dynamic corner frequency can accurately reflect the rupture directivity *** applied our modified method to simulate near-field strong motions within 150 km of the 2008 MW7.9 Wenchuan earthquake *** modified method performed well over a broad period range,particularly at 0.04-4 *** total deviations of the stochastic finite-fault method(EXSIM)and the modified EXSIM were 0.1676 and 0.1494,*** modified method can effectively account for the influence of the rupture propagation direction and provide more realistic ground motion estimations for earthquake disaster mitigation.

关键词： stochastic finite-fault method dynamic corner frequency Wenchuan earthquake rupture propagation direction

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Effect of Polyvinyl Alcohol in Inner Aqueous Phase on Stability of Millimeter-scale Capsules

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 506-511页

作者：黄乐平 LI Shidong ZHANG Jiabei pan Chenchen 赵瑾朝 School of Material Science and Engineering Wuhan Textile UniversityWuhan 430200China Hubei Provincial Engineering Laboratory for Clean Production and High Value Utilization of Bio-Based Textile Materials Wuhan Textile UniversityWuhan 430200China

The millimeter-scale capsules with controllable morphology,ultra-low permeability and excellent mechanical stability were fabricated by *** of inner phase was adjusted to control the morphology and properties of the *** detail,as the concentration of polyvinyl alcohol(PVA)increased from 0 to 8% in the inner phase of the capsules,the diameter of capsules decreased from 3.33 ± 0.01mm to 2.97 ± 0.01 mm,the shell thickness of capsules decreased from 0.183 ± 0.004 mm to 0.155 ± 0.003 *** the capsules had round shape and high ***,the capsules with 2% PVA in the inner phase had remarkably decreased water permeability and good morphological ***,the end-time of water losing of the capsules was up to 49 days,while the dehydrated capsules maintained spherical appearance,and crushing force of the capsules was up to 13.73 ± 0.79 N,which ensured stability during processing and *** research provides a new strategy for stable encapsulation of small molecules.

关键词： capsule millimeter-scale millifluidics polyvinyl alcohol viscosity

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