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Coupled GIMP and CPDI material point method in modelling blast-induced three-dimensional rock fracture

International Journal of Mining Science and Technology 2022年第5期32卷 1097-1114页

作者： Duanying Wan Meng Wang Zheming Zhu Fei Wang Lei Zhou ruifeng liu Weiting Gao Yun Shu Hu Xiao MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu 610065China State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resources and HydropowerSichuan UniversityChengdu 610065China College of Civil and Architecture Engineering Panzhihua UniversityPanzhihua 617099China

Three-dimensional rock fracture induced by blasting is a highly complex problem and has received considerable attention in geotechnical engineering.The material point method is firstly applied to treat this challenging task.Some inherent weaknesses can be overcome by coupling the generalized interpolation material point(GIMP)and the convected particle domain interpolation technique(CPDI).For the media in the borehole,unchanged GIMP-type particles are used to guarantee a homogenous blast pressure.CPDITetrahedron type particles are employed to avoid the fake numerical fracture near the borehole for the rock material.A blasting experiment using three-dimensional single-borehole rock was simulated to examine the applicability of the coupled model under realistic loading and boundary conditions.A good agreement was achieved between the simulation and experimental results.Moreover,the mechanism of three-dimensional rock fracture was analyzed.It was concluded that rock particle size and material parameters play an important role in rock damage.The reflected tensile waves cause severe damage in the lower part of the model.Rayleigh waves occur on the top face of the rock model to induce a hoop failure band.

关键词： Material point method(MPM) Convected particle domain interpolation (CPDI) Generalized interpolation material point (GIMP) Rock fracture Blast

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Defects and asymmetries in the visual pathway of non-human primates with natural strabismus and amblyopia

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Zoological Research 2023年第1期44卷 153-168页

作者： Feng liu Zhong-Hao Wang Wanjing Huang Ying Xu Xuan Sang ruifeng liu Zhou-Yue Li Ya-Lan Bi Lei Tang Jing-Yi Peng Jia-Ru Wei Zhi-Chao Miao Jian-Hua Yan Sheng liu State Key Laboratory of Ophthalmology Zhongshan Ophthalmic CenterSun Yat-Sen UniversityGuangdong Provincial Key Laboratory of Ophthalmology and Visual ScienceGuangzhouGuangdong 510060China Guangdong-Hongkong-Macao Institute of CNS Regeneration Jinan UniversityGuangzhouGuangdong 510632China European Molecular Biology Laboratory European Bioinformatics Institute(EMBL-EBI)Wellcome Genome CampusCambridge CB101SDUK Translational Research Institute of Brain and Brain-Like Intelligence and Department of Anesthesiology Shanghai Fourth People’s Hospital Affiliated to Tongji University School of MedicineShanghai 200081China Guangdong Province Key Laboratory of Brain Function and Disease GuangzhouGuangdong 510080China

Strabismus and amblyopia are common ophthalmologic developmental diseases caused by abnormal visual experiences. However, the underlying pathogenesis and visual defects are still not fully understood. Most studies have used experimental interference to establish diseaseassociated animal models, while ignoring the natural pathophysiological mechanisms. This study was designed to investigate whether natural strabismus and amblyopia are associated with abnormal neurological defects. We screened one natural strabismic monkey(Macaca fascicularis) and one natural amblyopic monkey from hundreds of monkeys, and retrospectively analyzed one human strabismus case. Neuroimaging, behavioral,neurophysiological, neurostructural, and genovariation features were systematically evaluated using magnetic resonance imaging(MRI), behavioral tasks, flash visual evoked potentials(FVEP),electroretinogram(ERG), optical coherence tomography(OCT), and whole-genome sequencing(WGS), respectively. Results showed that the strabismic patient and natural strabismic and amblyopic monkeys exhibited similar abnormal asymmetries in brain structure, i.e., ipsilateral impaired right hemisphere. Visual behavior, visual function, retinal structure, and fundus of the monkeys were impaired. Aberrant asymmetry in binocular visual function and structure between the strabismic and amblyopic monkeys was closely related, with greater impairment of the left visual pathway.Several similar known mutant genes for strabismus and amblyopia were also identified. In conclusion,natural strabismus and amblyopia are accompanied by abnormal asymmetries of the visual system,especially visual neurophysiological and neurostructural defects. Our results suggest that future therapeutic and mechanistic studies should consider defects and asymmetries throughout the entire visual system.

关键词： Non-human primates Natural disease models Strabismic patients Strabismus Amblyopia

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Climate change and village adaptation impact on reliability of irrigation wells in China

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Chinese Journal of Population,Resources and Environment 2016年第3期16卷 215-226页

作者： ruifeng liu College of Economics and Management Henan Agricultural University

This paper builds a water supply reliability econometric model to analyze climate changes and adaptation impact factors on water supply reliability of irrigation wells by using 100 villages' three-year(2010-2012) field survey data of five middle and eastern provinces of China.The results show that long-run climate change factors,adaptation measures,village-level organizations of irrigation management,as well as extreme climate factors affect the water supply reliability of irrigation wells significantly.Meanwhile,there are significant differences impacting different crops and provinces.This paper suggests that agriculture meteorological disaster monitoring and warning systems should be strengthened by increasing irrigation facilities construction and maintenance,promoting reform of agricultural irrigation water management system,and developing various forms of peasant cooperation organization in order to improve agricultural production capacity to adapt to climate change.

关键词： Climate change water supply reliability irrigation wells groundwater resources China

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中国青藏高原M≥6.0地震的辐射能量测定

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地震学报 2024年第3期46卷 442-457页

作者：孔韩东刘瑞丰边银菊刘伟中国地震局地球物理研究所北京100081 中国地震局第二监测中心西安710054

地震辐射能量主要由高频体波携带,与震源动态特征直接相关,能够有效地弥补地震矩和矩震级对震源动态过程和高频成分描述的不足,为地震应急和灾害评估提供更为全面的参考。本文使用自主研发的地震辐射能量测定软件测定了中国青藏高原自1... 详细信息

地震辐射能量主要由高频体波携带,与震源动态特征直接相关,能够有效地弥补地震矩和矩震级对震源动态过程和高频成分描述的不足,为地震应急和灾害评估提供更为全面的参考。本文使用自主研发的地震辐射能量测定软件测定了中国青藏高原自1990年以来M≥6.0浅源地震的地震辐射能量,并初步分析了中国青藏高原地区浅源地震的能量释放规律。研究结果表明:(1)利用该软件测定的中国青藏高原地区的34例浅源地震所得的测定结果稳定可靠。在一般情况下,地震的矩震级M_(W)与能量震级M_(e)并不相等,为了更全面地评估地震动效应,不仅需要考虑地震断层错动的静态特征,还需要考虑震源的动态特性。因此,在表示震源特性时,矩震级M_(W)和能量震级M_(e)各有特点,优势互补。(2)改则地震和尼玛地震的能量震级分别为6.47和6.00,地震辐射能量分别为1.26×10^(14) J和0.25×10^(14) J。两次震源位置相近、矩震级相同的地震,所释放的能量相差5倍之多。为了探究改则地震与尼玛地震能量释放差异的原因,我们通过S变换对两次地震的波形进行了时频分析。结果表明,震源动态过程的不同导致了地震辐射能量释放过程的差异。因此能量震级和地震辐射能量等动态震源参数比矩震级更适合描述震源的动态过程和地震的潜在破坏性。(3)结合地震矩资料得到中国青藏高原地区浅源地震的平均能矩比为1.9×10^(-5),是全球浅源地震平均能矩比的1.6倍。能矩比的大小与震源机制有关,走滑型地震的平均能矩比高于倾滑型地震。(4)中国青藏高原浅源地震的能矩比分布存在区域特征,东部和西部平均能矩比分别为2.25×10^(-5)和1.62×10^(-5),东部明显高于西部。能矩比的区域性差异与地质构造背景有关,地震辐射能量能够反映该地区的地质构造状态。同一区域内地震的能矩比也存在差别,中国青藏高原地区浅源地震的能矩比范围为5.03×10^(-6)—4.80×10^(-5),反映了不同断层上发生的地震能量释放过程存在差异。因此,为全面反映地震的震源特性有必要进行能量震级和矩震级的联合测定。

关键词：中国青藏高原地震辐射能量能量震级能矩比矩震级动态震源参数

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Investigation on Fracture Properties of Single-Flawed Tunnel Model Under Medium-to-Low-Speed Impacts

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Acta Mechanica Solida Sinica 2020年第2期33卷 205-225页

作者： Lei Zhou Zheming Zhu ruifeng liu Yong Fan Yuqing Dong Peng Ying State Key Laboratory of Hydraulics and Mountain River Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Key Laboratory of Deep Underground Science and Engineering(Ministry of Education) College of Architecture and EnvironmentSichuan UniversityChengdu 610065China

Dynamic fractures occur frequently in geophysical processes and engineering applications.It is thus essential to study crack and failure behaviors,such as crack time-to-initiation,crack growth rate and arrest period under dynamic loading.In this study,impact experiments were implemented by utilizing the single-flawed tunnel specimens under drop-hammer impacts.Four brittle materials,i.e.,green sandstone,red sandstone,black sandstone and polymethyl methacrylate,were selected to make single-flawed tunnel specimens.Strain gauges and crack extension gauges were employed to measure the crack extension parameters.The properties of crack growth rate,crack time-to-initiation and arrest period of these four brittle materials were discussed and analyzed.The corresponding numerical simulation was performed by using the commercial software AUTODYN.The numerical results of crack growth rate and crack time-to-initiation agreed with the impact test results.The commercial software ABAQUS was applied to compute the dynamic stress intensity factors.The results show that both the dynamic initiation fracture toughness and the crack growth rate increase with the elastic moduli of these four types of brittle materials under the same loading conditions,whereas the crack time-to-initiation decreases with the increase in elastic moduli of the brittle materials under the same loading conditions.

关键词： Single-flawed tunnel Impact loading Crack growth rate Crack time-to-initiation Initiation fracture toughness

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Preliminary study of lateral variation in crustal structure of Northeast China from teleseismic receiver functions

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Earthquake Science 2011年第1期24卷 15-25页

作者： Youlin Chen ruifeng liu Zhibin Huang Li Sun Array Information Technology Maryland 20770 USA China Earthquake Networks Center Beijing 100045 China

We conducted comprehensive receiver function analyses for a large amount of high-quality broadband teleseismic waveforms data recorded at 19 China National Digital Seismic Network （CNDSN） stations deployed in Northeast China. An advanced H-κ domain search method was adopted to accurately estimate the crustal thickness and vp/vs ratio. The crust has an average thickness of about 34.4 km. The thinnest crust occurs in the central region of Northeast China, while the thickest crust is beneath the Yanshan belt. The vp/vs ratio is relatively uniform with an average of about 1.733. The highest vp/vs ratio is found beneath the Changbaishan, likely associated with its volcanic activities. We found significant lateral heterogeneity beneath three stations CN2, MDJ, and MIH located along the Suolon suture from the back-zimuthal dependence of Moho depth. The velocity modeling from receiver functions indicated complicated Earth structure beneath these stations with large crust-mantle transition zone, noticeable velocity jump in upper mantle, and low velocity zone in middle crust. Dipping velocity interface in the crust with strike approximately parallel to the Suolon suture and down-dip to the south or southeast might explain the observed lateral heterogeneity.

关键词： Moho crust receiver function lateral heterogeneity

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彩色多普勒超声对糖尿病足患者下肢动脉病变的应用价值分析

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糖尿病新世界 2024年第1期27卷 179-181,189页

作者：刘瑞锋临沂老年医院超声科山东临沂276000

目的对糖尿病足患者下肢动脉病变诊断中行彩色多普勒超声的应用价值进行分析。方法选取2022年4月—2023年4月临沂老年医院收治的90例糖尿病足患者为研究对象,按照糖尿病足分级标准分为坏疽组(n=42)、非坏疽组(n=48),均提供彩色多普勒... 详细信息

目的对糖尿病足患者下肢动脉病变诊断中行彩色多普勒超声的应用价值进行分析。方法选取2022年4月—2023年4月临沂老年医院收治的90例糖尿病足患者为研究对象,按照糖尿病足分级标准分为坏疽组(n=42)、非坏疽组(n=48),均提供彩色多普勒超声诊断,对彩色多普勒超声的应用价值进行评价。结果坏疽组的左侧和右侧下肢动脉病变内径(股动脉、股浅动脉、股深动脉、胫后动脉、腘动脉、足背动脉)均小于非坏疽组,差异有统计学意义(P均<0.05)。坏疽组的股动脉血流参数(舒张期末血流速度、收缩期最大峰值血流速度、搏动指数、阻力指数)与腘动脉血流参数(舒张期末血流速度、收缩期最大峰值血流速度、搏动指数、阻力指数)显著小于非坏疽组,差异有统计学意义(P均<0.05)。结论彩色多普勒在糖尿病足的临床诊断中具有较高的临床应用价值,可以为临床诊治提供参考。

关键词：彩色多普勒超声糖尿病足下肢动脉病变诊断

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Focal mechanism of Luding M 6.8 earthquake, September 2022 and analysis of the loading role of the tectonic stress on the seismogenic fault

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Earthquake Research Advances 2023年第3期3卷 1-10页

作者： Yansong Hu Zhenyue Li ruifeng liu Zibo Wang Institute of Geophysics China Earthquake AdministrationBeijingChina

To reveal the seismogenic mechanism of the Luding earthquake, we employed the 118 China Seismic Network stations to collect the P-wave polarity data from each station, which was then used in the P-wave first motion approach to calculate the focal mechanism solution of the M6.8 Luding earthquake that occurred on September 5,2022. We have also studied the loading effect of tectonic stress on the Luding earthquake fault based on the stress field data for the research area. The results indicate that this earthquake was a strike-slip type, the nodal plane I:strike 167°, dip angle 78°, slip angle 2°;Nodal plane II: strike 77°, dip angle 88°, slip angle 168°. The two fault planes’ instability coefficients of the Luding earthquake are examined considering the region’s background stress field’s condition. The nodal plane I in the Moho circle is discovered to practically coincide with the Coulomb failure line and the tangent point of the Moho circle, indicating that this nodal plane has a high instability coefficient compared to the nodal plane II. The conclusion is that the nodal plane I has a higher likelihood of being the seismogenic fault plane, which is congruent with the seismogenic fault plane suggested by the aftershock distribution, the earthquake radiation energy distribution of a single station, and seismic intensity distribution.The Luding earthquake’s focal mechanism is highly like the theoretical focal mechanism of the fault situated at the location where the Coulomb failure line intersects the Mohr circle, demonstrating that background stress is what caused the earthquake. The substantial fault instability and similarity between the solved and theoretical focal mechanisms make it easier to comprehend the loading effect of tectonic stress on the Luding earthquake fault.

关键词： Luding M 6.8 earthquake P-wave first motion Focal mechanism Background stress

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小农户与新型农业经营主体有机衔接意愿研究--以河南省林州市为例

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中国农机化学报 2024年第5期45卷 299-309页

作者：王剑刘瑞峰梁飞李幸子马恒运河南农业大学经济与管理学院郑州市450002

充分发挥新型农业经营主体对小农户引领、示范和带动作用,是破解“小农困境”、促进小农户对接现代农业有效举措。基于河南省林州市444名农户微观调查数据,运用Logistic回归模型对小农户衔接对象选择意愿和持续衔接意愿的影响因素开展... 详细信息

充分发挥新型农业经营主体对小农户引领、示范和带动作用,是破解“小农困境”、促进小农户对接现代农业有效举措。基于河南省林州市444名农户微观调查数据,运用Logistic回归模型对小农户衔接对象选择意愿和持续衔接意愿的影响因素开展实证研究。研究结果表明:农户年龄、农户受教育年限、外出务工经历、农业收入占比、农产品类型、农业技术服务、农产品品牌化程度、政策宣传等变量是影响小农户衔接对象选择意愿主要因素;外出务工经历、农业技术服务、衔接内容约定方式、机械化投入、收益满意程度等变量对小农户持续衔接意愿均具有显著正向影响。为促进小农户与新型农业经营主体更加高效衔接,应尊重小农户衔接意愿,鼓励其因地制宜、因时制宜地选择衔接对象和方式;引导小农户与新型农业经营主体在衔接过程中发挥各自优势,共同发展生产,面对市场;培育新型职业农民,创造条件鼓励小农户实现自主转型发展。

关键词：新型农业经营主体小农户农业现代化有机衔接选择意愿

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Probing the fractional topological charge of a vortex light beam by using dynamic angular double slits

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Photonics Research 2016年第5期4卷 187-190页

作者： Jing Zhu Pei Zhang Dongzhi Fu Dongxu Chen ruifeng liu Yingnan Zhou Hong Gao Fuli Li Laboratory of Quantum Information and Quantum Optoelectronic Devices Shaanxi ProvinceXian Jiaotong University Key Laboratory of Quantum Information University of Science and Technology of ChinaChinese Academy of Science

Vortex beams with fractional topological charge(FTC) have many special characteristics and novel applications.However, one of the obstacles for their application is the difficulty of precisely determining the FTC of fractional vortex beams. We find that when a vortex beam with an FTC illuminates a dynamic angular double slit(ADS), the far-field interference patterns that include the information of the FTC of the beam at the angular bisector direction of the ADS vary periodically. Based on this property, a simple dynamic ADS device and data fitting method can be used to precisely measure the FTC of a vortex light beam with an error of less than 5%.

关键词： Probing the fractional topological charge of a vortex light beam by using dynamic angular double slits

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