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Analysis of Chinese/English Codeswitching on Network Language by Figure/ground Theory
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作者 马玉波 《中国校外教育》 2011年第6期42-42,122,共2页
With the rapid development of network language,more and more phenomena of Chinese/English Codeswitching appear in our daily communications.Codeswitching research of the network language is a new aspect in the linguist... With the rapid development of network language,more and more phenomena of Chinese/English Codeswitching appear in our daily communications.Codeswitching research of the network language is a new aspect in the linguistic field.The paper starts from cognitive perspective to discuss the process of Chinese/English Codeswitching by Figure/ground theory. 展开更多
关键词 网络语言 言语交际 语码转换 汉语 英语
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汉语名词短语及存现句语序的“Ground-to-Figure”假说 被引量:1
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作者 郑晓行 《现代语文(下旬.语言研究)》 2015年第8期57-62,共6页
20世纪以来的汉语语序研究虽然取得了不少成果,但仍需要全面、系统和深入的研究。从"以运用为基础"的认知语言学研究范式来看,汉语句法结构通过概念隐喻在汉语使用者的日常空间思维的基础上生成,因此,汉语名词短语:"……... 20世纪以来的汉语语序研究虽然取得了不少成果,但仍需要全面、系统和深入的研究。从"以运用为基础"的认知语言学研究范式来看,汉语句法结构通过概念隐喻在汉语使用者的日常空间思维的基础上生成,因此,汉语名词短语:"……>名词整体(背景)>名词部分(图形)>……""……>名词大(背景)>名词小(图形)>……""……>名词空间/时间(背景)>名词对象(图形)>……"和存现句"……(NPloc/time)……(V)……(NP)……"等语序在汉语使用者的"Ground-to-Figure"的认知过程的基础上生成。在此基础上提出的汉语名词短语及存现句的"Ground-to-Figure"假说是一条汉语语序生成的重要机制,但不是唯一机制。 展开更多
关键词 汉语名词短语 存现句 语序 ground—to—figure
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Figure-9腔锁模全保偏掺铒光纤飞秒激光器
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作者 杨小亮 韦佳天 +2 位作者 吕宏伟 陈峰 刘志强 《光通信技术》 2023年第5期58-62,共5页
针对特殊应用领域对高可靠性、轻量化、输出功率大于100 mW、重频大于50 MHz的飞秒激光器的需求,设计了一种Figure-9腔锁模全保偏掺铒光纤飞秒激光器,通过在腔锁模振荡器中引入π/2相移偏置,降低了振荡器的自启动锁模阈值。实验结果表明... 针对特殊应用领域对高可靠性、轻量化、输出功率大于100 mW、重频大于50 MHz的飞秒激光器的需求,设计了一种Figure-9腔锁模全保偏掺铒光纤飞秒激光器,通过在腔锁模振荡器中引入π/2相移偏置,降低了振荡器的自启动锁模阈值。实验结果表明:当泵浦功率为130 mW时,振荡器可获得平均功率为12 mW、重频为85.89 MHz、脉冲宽度为249 fs的稳定锁模脉冲序列输出;采用一级正色后向泵浦散掺铒增益光纤放大器进行放大后,最终可获得平均功率为113 mW、脉冲宽度为107 fs的飞秒脉冲序列输出。 展开更多
关键词 保偏 figure-9腔 激光器 锁模 非线性放大光纤环
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汉语名词短语左递归现象的“Ground-to-Figure”假说——兼论Hauser,Chomsky&Fitch的FLN假说
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作者 郑晓行 曹杰旺 《淮南师范学院学报》 2016年第1期81-87,共7页
Hauser,Chomsky&Fitch(2002)把"语言器官"区分为FLB和FLN,并假设FLN只包含递归性,(递归性)是人类语言器官独有且唯一的构成要素,它使人类语言可以对"有限的手段进行无限运用"。按照他们的观点,类似汉语名词短... Hauser,Chomsky&Fitch(2002)把"语言器官"区分为FLB和FLN,并假设FLN只包含递归性,(递归性)是人类语言器官独有且唯一的构成要素,它使人类语言可以对"有限的手段进行无限运用"。按照他们的观点,类似汉语名词短语左递归现象均由FLN的递归性生成,这种观点明显不符合汉语实际,也不符合汉语使用者的认知过程。从完形心理学的图形-背景认知原则来说,汉语使用者在认知过程中遵循从背景到图形的顺序,不断切换关注中心,而语言表达也遵循从背景到图形的顺序与之对应,形成了语言使用者对外部事物的完形认知与语言完形表达的异质同构,这就是汉语名词左递归现象的"Ground-to-Figure"假说。汉语名词左递归现象植根于汉语使用者的空间认知,这种语言思维与空间思维之间的同一性关系也得到Lakoff(1987)提出的形式空间化假设的有力的支持,而形式空间化假设又被神经生理学和生物学的研究成果的证实:人类空间思维与语言思维在人类大脑神经系统中由同类结构生成。诸如汉语名词左递归现象的语言递归现象并不是由所谓的FLN的递归性生成,递归性也不是区域限定性的而是区域通用性的,不为FLN独有。从这个意义上说,Hauser,Chomsky&Fitch(2002)的FLN假说是错误的。 展开更多
关键词 汉语名词短语左递归现象 'ground-to-figure'假说 递归性 FLB FLN
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Comparative Analysis of Equal and Unequal Grounding Grid Configurations by Compression Ratio and Least Square Curve Fitting Techniques
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作者 M.Soni Abraham George 《Energy Engineering》 EI 2023年第3期597-616,共20页
The primary aim of the power system grounding is to safeguard the person and satisfying the performance of the power systemtomaintain reliable operation.With equal conductor spacing grounding grid design,the distribut... The primary aim of the power system grounding is to safeguard the person and satisfying the performance of the power systemtomaintain reliable operation.With equal conductor spacing grounding grid design,the distribution of the current in the grid is not uniform.Hence,unequal grid conductor span in which grid conductors are concentrated more at the periphery is safer to practice than equal spacing.This paper presents the comparative analysis of two novel techniques that create unequal spacing among the grid conductors:the least-square curve fitting technique and the compression ratio techniquewith equal grid configuration for both square and rectangular grids.Particle Swarm Optimization(PSO)is adopted for finding out one optimal feasible solution among many feasible solutions of equal grid configuration for both square and rectangular grids.Comparative analysis is also carried out between square and rectangular grids using the least square curve fitting technique as it results in only one unequal grid configuration.Simulation results are obtained by theMATLAB software developed.Percentage of improvement in ground potential rise,step voltage,touch voltage,and grid resistancewith variation in compression ratios are plotted. 展开更多
关键词 ground grid design ground potential rise grid resistance compression ratio least square curve fitting touch voltage step voltage PSO
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Consolidation of high replacement ratio stone column-reinforced ground:Analytical solutions incorporating clogging effect
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作者 Jinxin Sun Mengmeng Lu +1 位作者 Baolong Xu Jie Shan 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3311-3326,共16页
The utilization of stone columns has emerged as a popular ground improvement strategy,whereas the drainage performance can be adversely hampered by clogging effect.Despite the ample progress of calculation methods for... The utilization of stone columns has emerged as a popular ground improvement strategy,whereas the drainage performance can be adversely hampered by clogging effect.Despite the ample progress of calculation methods for the consolidation of stone column-improved ground,theoretical investigations into the clogging effect have not been thoroughly explored.Furthermore,it is imperative to involve the column consolidation deformation to mitigate computational error on the consolidation of composite ground with high replacement ratios.In this context,an analytical model accounting for the initial clogging and coupled time and depth-dependent clogging of stone columns is established.Then,the resulting governing equations and analytical solutions are obtained under a new flow continuity relationship to incorporate column consolidation deformation.The accuracy and reliability of the proposed model are illustrated by degradation analysis and case studies with good agreements.Subsequently,the computed results of the current study are juxtaposed against the existing models,and an in-depth assessment of the impacts of several crucial parameters on the consolidation behavior is conducted.The results reveal that ignoring column consolidation deformation leads to an overestimate of the consolidation rate,with maximum error reaching up to 16%as the replacement ratio increases.Furthermore,the initial clogging also has a significant influence on the consolidation performance.Additionally,the increment of depth and time-clogging factors a and b will induce a noticeable retardation of the consolidation process,particularly in the later stage. 展开更多
关键词 CONSOLIDATION Composite ground Stone column Clogging effect ground improvement Analytical model
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Perspectives in human brain plasticity sparked by glioma invasion:from intraoperative(re)mappings to neural reconfigurations
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作者 Sam Ng Hugues Duffau Guillaume Herbet 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第5期947-948,共2页
Exploring the aptitude of the human brain to compensate functional consequences of a lesion damaging its structural architecture is a key challenge to improve patient care in various neurological diseases,to optimize ... Exploring the aptitude of the human brain to compensate functional consequences of a lesion damaging its structural architecture is a key challenge to improve patient care in various neurological diseases,to optimize neuroscientifically-informed strategies of postlesional rehabilitation,and ultimately to develop innovative neuro-regenerative therapies.The term‘plasticity’,initially referring to the intrinsic propensity of neurons to modulate their synaptic transmission in a learning situation,was progressively transposed to brain injury research and clinical neurosciences.Indeed,in the event of brain damage,adaptive mechanisms of compensation allow a partial reshaping of the structure and activities of the central nervous system,thus permitting to some extent the maintenance of brain functions. 展开更多
关键词 PLASTICITY figuration consequences
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Pulses in ground motions identified through surface partial matching and their impact on seismic rocking consequence
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作者 Tang Yuchuan Wang Jiankang Wu Gang 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第1期35-50,共16页
In seismology and earthquake engineering,it is fundamental to identify and characterize the pulse-like features in pulse-type ground motions.To capture the pulses that dominate structural responses,this study establis... In seismology and earthquake engineering,it is fundamental to identify and characterize the pulse-like features in pulse-type ground motions.To capture the pulses that dominate structural responses,this study establishes congruence and shift relationships between response spectrum surfaces.A similarity search between spectrum surfaces,supplemented with a similarity search in time series,has been applied to characterize the pulse-like features in pulse-type ground motions.The identified pulses are tested in predicting the rocking consequences of slender rectangular blocks under the original ground motions.Generally,the prediction is promising for the majority of the ground motions where the dominant pulse is correctly identified. 展开更多
关键词 velocity pulse ground motion surface similarity ROCKING OVERTURNING
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An efficient physics-guided Bayesian framework for predicting ground settlement profile during excavations in clay
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作者 Cong Tang Shuyu He Wanhuan Zhou 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1411-1424,共14页
Recently,the application of Bayesian updating to predict excavation-induced deformation has proven successful and improved prediction accuracy significantly.However,updating the ground settlement profile,which is cruc... Recently,the application of Bayesian updating to predict excavation-induced deformation has proven successful and improved prediction accuracy significantly.However,updating the ground settlement profile,which is crucial for determining potential damage to nearby infrastructures,has received limited attention.To address this,this paper proposes a physics-guided simplified model combined with a Bayesian updating framework to accurately predict the ground settlement profile.The advantage of this model is that it eliminates the need for complex finite element modeling and makes the updating framework user-friendly.Furthermore,the model is physically interpretable,which can provide valuable references for construction adjustments.The effectiveness of the proposed method is demonstrated through two field case studies,showing that it can yield satisfactory predictions for the settlement profile. 展开更多
关键词 Bayesian updating EXCAVATIONS ground settlement profile Simplified model UNCERTAINTY
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Ground threat prediction-based path planning of unmanned autonomous helicopter using hybrid enhanced artificial bee colony algorithm
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作者 Zengliang Han Mou Chen +1 位作者 Haojie Zhu Qingxian Wu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第2期1-22,共22页
Unmanned autonomous helicopter(UAH)path planning problem is an important component of the UAH mission planning system.Aiming to reduce the influence of non-complete ground threat information on UAH path planning,a gro... Unmanned autonomous helicopter(UAH)path planning problem is an important component of the UAH mission planning system.Aiming to reduce the influence of non-complete ground threat information on UAH path planning,a ground threat prediction-based path planning method is proposed based on artificial bee colony(ABC)algorithm by collaborative thinking strategy.Firstly,a dynamic threat distribution probability model is developed based on the characteristics of typical ground threats.The dynamic no-fly zone of the UAH is simulated and established by calculating the distribution probability of ground threats in real time.Then,a dynamic path planning method for UAH is designed in complex environment based on the real-time prediction of ground threats.By adding the collision warning mechanism to the path planning model,the flight path could be dynamically adjusted according to changing no-fly zones.Furthermore,a hybrid enhanced ABC algorithm is proposed based on collaborative thinking strategy.The proposed algorithm applies the leader-member thinking mechanism to guide the direction of population evolution,and reduces the negative impact of local optimal solutions caused by collaborative learning update strategy,which makes the optimization performance of ABC algorithm more controllable and efficient.Finally,simulation results verify the feasibility and effectiveness of the proposed ground threat prediction path planning method. 展开更多
关键词 UAH Path planning ground threat prediction Hybrid enhanced Collaborative thinking
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Thermal performance of cast-in-place piles with artificial ground freezing in permafrost regions
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作者 WANG Xinbin CHEN Kun +3 位作者 YU Qihao GUO Lei YOU Yanhui JIN Mingyang 《Journal of Mountain Science》 SCIE CSCD 2024年第4期1307-1328,共22页
During the construction of cast-in-place piles in warm permafrost,the heat carried by concrete and the cement hydration reaction can cause strong thermal disturbance to the surrounding permafrost.Since the bearing cap... During the construction of cast-in-place piles in warm permafrost,the heat carried by concrete and the cement hydration reaction can cause strong thermal disturbance to the surrounding permafrost.Since the bearing capacity of the pile is quite small before the full freeze-back,the quick refreezing of the native soils surrounding the cast-in-place pile has become the focus of the infrastructure construction in permafrost.To solve this problem,this paper innovatively puts forward the application of the artificial ground freezing(AGF)method at the end of the curing period of cast-in-place piles in permafrost.A field test on the AGF was conducted at the Beiluhe Observation and Research Station of Frozen Soil Engineering and Environment(34°51.2'N,92°56.4'E)in the Qinghai Tibet Plateau(QTP),and then a 3-D numerical model was established to investigate the thermal performance of piles using AGF under different engineering conditions.Additionally,the long-term thermal performance of piles after the completion of AGF under different conditions was estimated.Field experiment results demonstrate that AGF is an effective method to reduce the refreezing time of the soil surrounding the piles constructed in permafrost terrain,with the ability to reduce the pile-soil interface temperatures to below the natural ground temperature within 3 days.Numerical results further prove that AGF still has a good cooling effect even under unfavorable engineering conditions such as high pouring temperature,large pile diameter,and large pile length.Consequently,the application of this method is meaningful to save the subsequent latency time and solve the problem of thermal disturbance in pile construction in permafrost.The research results are highly relevant for the spread of AGF technology and the rapid building of pile foundations in permafrost. 展开更多
关键词 Permafrost engineering Cast-in-place pile Artificial ground freezing Thermal performance.
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Ground settlement and tunnel response due to twin-curved shield tunnelling in soft ground with small clear distance
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作者 Yao Hu Haoran Tang +4 位作者 Yinggang Xu Huayang Lei Peng Zeng Kai Yao Yabo Dong 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3122-3135,共14页
Twin curved tunnels are often encountered in shield tunnelling,where significant complexities in densely exploited underground space are observed.In this study,the ground settlement and tunnel deformation due to twin-... Twin curved tunnels are often encountered in shield tunnelling,where significant complexities in densely exploited underground space are observed.In this study,the ground settlement and tunnel deformation due to twin-curved shield tunnelling in soft ground were investigated using numerical simulation and field monitoring.Different curvature radii of twin curved tunnels and subsequent effects of tunnel construction were considered to reveal the tunnelling effect on ground surface settlement and tunnel deformation.The results show that the settlement trough yields one offset towards inside of curved shield tunnelling.The location of settlement trough and maximum settlement were affected by curvature radius but except for the shape and width of settlement trough.Adjacent parallel twin-curved shield tunnelling could increase the offset of existing settlement trough and maximum settlement.Then,an empirical prediction of surface settlement trough due to twin-curved shield tunnelling with same tunnel diameters in soft clay was proposed,which was applicable to curvature radius less than 800 m.Finally,a minimum radius of 600 m of curvature tunnel was proposed in terms of allowable convergence deformation of tunnel.The result could provide guidance on safety evaluation for twin curved shield tunnelling construction. 展开更多
关键词 Shield tunnelling Curvature radius ground settlement Tunnel deformation Numerical simulation
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Artificial ground freezing of underground mines in cold regions using thermosyphons with air insulation
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作者 Ahmad F.Zueter Mohammad Zolfagharroshan +1 位作者 Navid Bahrani Agus P.Sasmito 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第5期643-654,共12页
Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying availabl... Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying available cold wind in cold regions.This is achieved by a static heat transfer device called thermosyphon equipped with an air insulation layer.A refrigeration unit can be optionally integrated to meet additional cooling requirements.The introduction of air insulation isolates the thermosyphon from ground zones where freezing is not needed,resulting in:(1)steering the cooling resources(cold wind or refrigeration)towards zones of interest;and(2)minimizing refrigeration load.This design is demonstrated using well-validated mathematical models from our previous work based on two-phase enthalpy method of the ground coupled with a thermal resistance network for the thermosyphon.Two Canadian mines are considered:the Cigar Lake Mine and the Giant Mine.The results show that our proposed design can speed the freezing time by 30%at the Giant Mine and by two months at the Cigar Lake Mine.Further,a cooling load of 2.4 GWh can be saved at the Cigar Lake Mine.Overall,this study provides mining practitioners with sustainable solutions of underground AGF. 展开更多
关键词 Artificial ground freezing Underground mining Sustainable mining THERMOSYPHON Air insulation Cold regions
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Neural network study of the nuclear ground-state spin distribution within a random interaction ensemble
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作者 Deng Liu Alam Noor A +1 位作者 Zhen-Zhen Qin Yang Lei 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第3期216-227,共12页
The distribution of the nuclear ground-state spin in a two-body random ensemble(TBRE)was studied using a general classification neural network(NN)model with two-body interaction matrix elements as input features and t... The distribution of the nuclear ground-state spin in a two-body random ensemble(TBRE)was studied using a general classification neural network(NN)model with two-body interaction matrix elements as input features and the corresponding ground-state spins as labels or output predictions.The quantum many-body system problem exceeds the capability of our optimized NNs in terms of accurately predicting the ground-state spin of each sample within the TBRE.However,our NN model effectively captured the statistical properties of the ground-state spin because it learned the empirical regularity of the ground-state spin distribution in TBRE,as discovered by physicists. 展开更多
关键词 Neural network Two-body random ensemble Spin distribution of nuclear ground state
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Crack mechanism of ground fissures in loess layer of Fenwei Basin, China
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作者 LI Cong LU Quanzhong +2 位作者 WANG Feiyong LUO Wenchao XU Qiang 《Journal of Mountain Science》 SCIE CSCD 2024年第5期1683-1696,共14页
The Fenwei Basin, covered by loess, experiences severe ground fissure disasters. These disasters disrupt the continuity of the loess and pose significant threats to engineering construction safety along transportation... The Fenwei Basin, covered by loess, experiences severe ground fissure disasters. These disasters disrupt the continuity of the loess and pose significant threats to engineering construction safety along transportation routes. Nevertheless, the crack characteristics and the influence zone of ground fissures in the loess layer remain inadequately investigated. To effectively prevent and control ground fissure disasters, physical model tests and the PFC(particle flow code) numerical simulation method are used to investigate the crack mechanism of buried ground fissures in the loess layer. The results show that there are two main cracks in the layer profile, which have a Y-shape morphology. As the dip angle of the preset cracks increased from 60° to 90°, the main deformation zone at the surface gradually shifted towards the footwall. The process of crack propagation from depth to surface is divided into five stages. Additionally, the results confirm the accuracy of the width of the rupture zone d2in the footwall calculated by the cantilever beam theory. These findings can offer theoretical guidance for determining the avoidance distance of ground fissures in loess regions, as well as for implementing disaster prevention and corresponding control measures for various stages of buried ground fissure propagation. 展开更多
关键词 ground fissure Fenwei Basin Physical model test Particle flow code Crack propagation
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Chinese Liandong(Serial Verb) Constructions from the Perspective of Figure-Ground Relation
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作者 刘鹏 《海外英语》 2011年第1X期253-254,256,共3页
Empty categories,which lack phonological form and hence are not visible in the phonetic representation of the sentence,have both syntactic and semantic properties.Null subjects PRO and pro are base-generated empty cat... Empty categories,which lack phonological form and hence are not visible in the phonetic representation of the sentence,have both syntactic and semantic properties.Null subjects PRO and pro are base-generated empty categories.This thesis,based on Chomsky's theory about empty categories and research achievements made by Chinese scholars,attempts to analyze the liandong(Serial Verb) construction from Figure and Ground perspective. 展开更多
关键词 PRO Liandong(Serial) VERB construction figure-ground
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Characteristics of Lightning Activity in Southeast China and its Relation to the Atmospheric Background
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作者 支树林 朱杰 +1 位作者 刘岩 毛梦妮 《Journal of Tropical Meteorology》 SCIE 2024年第1期76-88,共13页
Based on the lightning observation data from the Fengyun-4A(FY-4A)Lightning Mapping Imager(FY-4A/LMI)and the Lightning Imaging Sensor(LIS)on the International Space Station(ISS),we extract the“event”type data as the... Based on the lightning observation data from the Fengyun-4A(FY-4A)Lightning Mapping Imager(FY-4A/LMI)and the Lightning Imaging Sensor(LIS)on the International Space Station(ISS),we extract the“event”type data as the lightning detection results.These observations are then compared with the cloud-to-ground(CG)lightning observation data from the China Meteorological Administration.This study focuses on the characteristics of lightning activity in Southeast China,primarily in Jiangxi Province and its adjacent areas,from April to September,2017–2022.In addition,with the fifth-generation European Centre for Medium-Range Weather Forecasts reanalysis data,we further delved into the potential factors influencing the distribution and variations in lightning activity and their primary related factors.Our findings indicate that the lightning frequency and density of the FY-4A/LMI,ISS-LIS and CG data are higher in southern and central Jiangxi,central Fujian Province,and western and central Guangdong Province,while they tend to be lower in eastern Hunan Province.In general,the high-value areas of lightning density for the FY-4A/LMI are located in inland mountainous areas.The lower the latitude is,the higher the CG lightning density is.High-value areas of the CG lightning density are more likely to be located in eastern Fujian and southeastern Zhejiang Province.However,the high-value areas of lightning density for the ISS-LIS are more dispersed,with a scattered distribution in inland mountainous areas and along the coast of eastern Fujian.Thus,the mountainous terrain is closely related to the high-value areas of the lightning density.The locations of the high-value areas of the lightning density for the FY-4A/LMI correspond well with those for the CG observations,and the seasonal variations are also consistent.In contrast,the distribution of the high-value areas of the lightning density for the ISS-LIS is more dispersed.The positions of the peak frequency of the FY-4A/LMI lightning and CG lightning contrast with local altitudes,primarily located at lower altitudes or near mountainsides.K-index and convective available potential energy(CAPE)can better reflect the local boundary layer conditions,where the lightning density is higher and lightning seasonal variations are apparent.There are strong correlations in the annual variations between the dew-point temperature(Td)and CG lightning frequency,and the monthly variations of the dew-point temperature and CAPE are also strongly correlated with monthly variations of CG lightning,while they are weakly correlated with the lightning frequency for the FY-4A/LMI and ISS-LIS.This result reflects that the CAPE shows a remarkable effect on the CG lightning frequency during seasonal transitions. 展开更多
关键词 LIGHTNING satellite and ground detections atmospheric background Southeast China
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Physical and numerical investigations of target stratum selection for ground hydraulic fracturing of multiple hard roofs
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作者 Binwei Xia Yanmin Zhou +2 位作者 Xingguo Zhang Lei Zhou Zikun Ma 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第5期699-712,共14页
Ground hydraulic fracturing plays a crucial role in controlling the far-field hard roof,making it imperative to identify the most suitable target stratum for effective control.Physical experiments are conducted based ... Ground hydraulic fracturing plays a crucial role in controlling the far-field hard roof,making it imperative to identify the most suitable target stratum for effective control.Physical experiments are conducted based on engineering properties to simulate the gradual collapse of the roof during longwall top coal caving(LTCC).A numerical model is established using the material point method(MPM)and the strain-softening damage constitutive model according to the structure of the physical model.Numerical simulations are conducted to analyze the LTCC process under different hard roofs for ground hydraulic fracturing.The results show that ground hydraulic fracturing releases the energy and stress of the target stratum,resulting in a substantial lag in the fracturing of the overburden before collapse occurs in the hydraulic fracturing stratum.Ground hydraulic fracturing of a low hard roof reduces the lag effect of hydraulic fractures,dissipates the energy consumed by the fracture of the hard roof,and reduces the abutment stress.Therefore,it is advisable to prioritize the selection of the lower hard roof as the target stratum. 展开更多
关键词 Target stratum selection ground hydraulic fracturing Hard roof control Fracture network Material point method
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The deterministic condition for the ground reaction force acting point on the combined knee valgus and tibial internal rotation moments in early phase of cutting maneuvers in female athletes
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作者 Issei Ogasawara Ken Ohta +4 位作者 Gajanan S.Revankar Shoji Konda Yohei Shimokochi Hideyuki Koga Ken Nakata 《Journal of Sport and Health Science》 SCIE CAS CSCD 2024年第3期376-386,共11页
Background:Combined knee valgus and tibial internal rotation(VL+IR)moments have been shown to stress the anterior cruciate ligament(ACL)in several in vitro cadaveric studies.To utilize this knowledge for non-contact A... Background:Combined knee valgus and tibial internal rotation(VL+IR)moments have been shown to stress the anterior cruciate ligament(ACL)in several in vitro cadaveric studies.To utilize this knowledge for non-contact ACL injury prevention in sports,it is necessary to elucidate how the ground reaction force(GRF)acting point(center of pressure(CoP))in the stance foot produces combined knee VL+IR moments in risky maneuvers,such as cuttings.However,the effects of the GRF acting point on the development of the combined knee VL+IR moment in cutting are still unknown.Methods:We first established the deterministic mechanical condition that the CoP position relative to the tibial rotational axis differentiates the GRF vector’s directional probability for developing the combined knee VL+IR moment,and theoretically predicted that when the CoP is posterior to the tibial rotational axis,the GRF vector is more likely to produce the combined knee VL+IR moment than when the CoP is anterior to the tibial rotational axis.Then,we tested a stochastic aspect of our theory in a lab-controlled in vivo experiment.Fourteen females performed 60˚cutting under forefoot/rearfoot strike conditions(10 trials each).The positions of lower limb markers and GRF data were measured,and the knee moment due to GRF vector was calculated.The trials were divided into anterior-and posterior-CoP groups depending on the CoP position relative to the tibial rotational axis at each 10 ms interval from 0 to 100 ms after foot strike,and the occurrence rate of the combined knee VL+IR moment was compared between trial groups.Results:The posterior-CoP group showed significantly higher occurrence rates of the combined knee VL+IR moment(maximum of 82.8%)at every time point than those of the anterior-CoP trials,as theoretically predicted by the deterministic mechanical condition.Conclusion:The rearfoot strikes inducing the posterior CoP should be avoided to reduce the risk of non-contact ACL injury associated with the combined knee VL+IR stress. 展开更多
关键词 Center of pressure Deterministic condition Foot strike pattern Injury mechanism Moment of ground reaction force
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Heat transfer and temperature evolution in underground mininginduced overburden fracture and ground fissures: Optimal time window of UAV infrared monitoring
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作者 Yixin Zhao Kangning Zhang +2 位作者 Bo Sun Chunwei Ling Jihong Guo 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第1期31-50,共20页
Heat transfer and temperature evolution in overburden fracture and ground fissures are one of the essential topics for the identification of ground fissures via unmanned aerial vehicle(UAV) infrared imager. In this st... Heat transfer and temperature evolution in overburden fracture and ground fissures are one of the essential topics for the identification of ground fissures via unmanned aerial vehicle(UAV) infrared imager. In this study, discrete element software UDEC was employed to investigate the overburden fracture field under different mining conditions. Multiphysics software COMSOL were employed to investigate heat transfer and temperature evolution of overburden fracture and ground fissures under the influence of mining condition, fissure depth, fissure width, and month alternation. The UAV infrared field measurements also provided a calibration for numerical simulation. The results showed that for ground fissures connected to underground goaf(Fissure Ⅰ), the temperature difference increased with larger mining height and shallow buried depth. In addition, Fissure Ⅰ located in the boundary of the goaf have a greater temperature difference and is easier to be identified than fissures located above the mining goaf. For ground fissures having no connection to underground goaf(Fissure Ⅱ), the heat transfer is affected by the internal resistance of the overlying strata fracture when the depth of Fissure Ⅱ is greater than10 m, the temperature of Fissure Ⅱ gradually equals to the ground temperature as the fissures’ depth increases, and the fissures are difficult to be identified. The identification effect is most obvious for fissures larger than 16 cm under the same depth. In spring and summer, UAV infrared identification of mining fissures should be carried out during nighttime. This study provides the basis for the optimal time and season for the UAV infrared identification of different types of mining ground fissures. 展开更多
关键词 Heat transfer Overburden fracture ground fissures Infrared thermal imaging Unmanned aerial vehicle(UAV) COMSOL simulation
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