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Vibration safety assessment and parameter analysis of buried oil pipelines based on vibration isolation holes under strong surface impact 被引量:1
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作者 Wang Guobo Mei Hua +4 位作者 Wang Jianning He Wei Yin Yao Zhai Yuxin Zuo Pengfei 《Earthquake Engineering and Engineering Vibration》 2025年第1期69-82,共14页
Strong surface impact will produce strong vibration,which will pose a threat to the safety of nearby buried pipelines and other important lifeline projects.Based on the verified numerical method,a comprehensive numeri... Strong surface impact will produce strong vibration,which will pose a threat to the safety of nearby buried pipelines and other important lifeline projects.Based on the verified numerical method,a comprehensive numerical parameter analysis is conducted on the key influencing factors of the vibration isolation hole(VIH),which include hole diameter,hole net spacing,hole depth,hole number,hole arrangement,and soil parameters.The results indicate that a smaller ratio of net spacing to hole diameter,the deeper the hole,the multi-row hole,the hole adoption of staggered arrangements,and better site soil conditions can enhance the efficiency of the VIH barrier.The average maximum vibration reduction efficiency within the vibration isolation area can reach 42.2%.The vibration safety of adjacent oil pipelines during a dynamic compaction projection was evaluated according to existing standards,and the measurement of the VIH was recommended to reduce excessive vibration.The single-row vibration isolation scheme and three-row staggered arrangement with the same hole parameters are suggested according to different cases.The research findings can serve as a reference for the vibration safety analysis,assessment,and control of adjacent underground facilities under the influence of strong surface impact loads. 展开更多
关键词 vibration isolation hole buried oil pipeline strong surface impact vibration velocity vibration safety assessment
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Impact of Surface Passivation on the Electronic Structure and Optical Properties of the Si1-xGex Nanowires 被引量:1
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作者 赖信 张析 +1 位作者 张依兮 向钢 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第2期119-122,共4页
The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires (NWs) passivated with different functional groups (-H, -F and-OH) are investigated by using first-principles calculations. ... The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires (NWs) passivated with different functional groups (-H, -F and-OH) are investigated by using first-principles calculations. The results show that surface passivation influences the characteristics of electronic band structures significantly: the band gap widths and types (direct or indirect) of the Si1-xGe, NWs with different terminators show complex and robust variations, and the effective masses of the electrons in the NWs can be modulated dramatically by the terminators. The study of optical absorption shows that the main peaks of the parallel polarization component of Si1-x Gex NWs passivated with the functional groups exhibit prominent changes both in height and position, and are red-shifted with respect to those of corresponding pure Si NWs, indicating the importance of both the terminators and Ge concentrations. Our results demonstrate that the electronic and optical properties of Si1-xGex NWs can be tuned by utilizing selected functional groups as well as particular Ge concentrations for customizing purposes. 展开更多
关键词 110 OH x)Ge_x Nanowires impact of surface Passivation on the Electronic Structure and Optical Properties of the Si Ge
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Defect-free surface of quartz glass polished in elastic mode by chemical impact reaction 被引量:1
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作者 彭文强 关朝亮 李圣怡 《Journal of Central South University》 SCIE EI CAS 2014年第12期4438-4444,共7页
Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom c... Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom can be recovered back to its original position without any defects introduced. Based on surface hydroxylation and chemisorption theory, material removal mechanism of quartz glass in the elastic mode is analyzed to obtain defect-free surface. Elastic contact condition between nanoparticle and quartz glass surface is confirmed from the Hertz contact theory model. Atoms on the quartz glass surface are removed by chemical bond generated by impact reaction in the elastic mode, so no defects are generated without mechanical process. Experiment was conducted on a numerically controlled system for nanoparticle jet polishing, and one flat quartz glass was polished in the elastic mode. Results show that scratches on the sample surface are completely removed away with no mechanical defects introduced, and microroughness(Ra) is decreased from 1.23 nm to 0.47 nm. Functional group Ce — O — Si on ceria nanoparticles after polishing was detected directly and indirectly by FTIR, XRD and XPS spectra analysis from which the chemical impact reaction is validated. 展开更多
关键词 defect-free surface chemical impact reaction nanoparticle jet polishing elastic mode
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Northern Hemisphere Sudden Stratospheric Warming and Its Downward Impact in Four Chinese CMIP6 Models 被引量:4
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作者 Jian RAO Siming LIU Yuanhao CHEN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2021年第2期187-202,共16页
Using the World Meteorological Organization definition and a threshold-based classification technique,simulations of vortex displacement and split sudden stratospheric warmings(SSWs)are evaluated for four Chinese mode... Using the World Meteorological Organization definition and a threshold-based classification technique,simulations of vortex displacement and split sudden stratospheric warmings(SSWs)are evaluated for four Chinese models(BCC-CSM2-MR,FGOALS-f3-L,FGOALS-g3,and NESM3)from phase 6 of the Coupled Model Intercomparison Project(CMIP6)with the Japanese 55-year reanalysis(JRA-55)as a baseline.Compared with six or seven SSWs in a decade in JRA-55,three models underestimate the SSW frequency by~50%,while NESM3 doubles the SSW frequency.SSWs mainly appear in midwinter in JRA-55,but one-month climate drift is simulated in the models.The composite of splits is stronger than displacements in both the reanalysis and most models due to the longer pulse of positive eddy heat flux before onset of split SSWs.A wavenumber-1-like temperature anomaly pattern(cold Eurasia,warm North America)before onset of displacement SSWs is simulated,but cold anomalies are mainly confined to North America after displacement SSWs.Although the lower tropospheric temperature also displays a wavenumber-1-like pattern before split SSWs,most parts of Eurasia and North America are covered by cold anomalies after split SSWs in JRA-55.The models have different degrees of fidelity for the temperature anomaly pattern before split SSWs,but the wavenumber-2-like temperature anomaly pattern is well simulated after split SSWs.The center of the negative height anomalies in the Pacific sector before SSWs is sensitive to the SSW type in both JRA-55 and the models.A negative North Atlantic Oscillation is simulated after both types of SSWs in the models,although it is only observed for split SSWs. 展开更多
关键词 sudden stratospheric warming CMIP6 surface impact model simulation
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Jump rule for edge impacts of rolling prisms 被引量:1
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作者 Zhen Zhao Nannan Wang Caishan Liu 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2018年第6期425-430,I0006,共7页
We study experimentally and theoretically the planar dynamics of purely rolling prisms on a rough ramp, where the rolling motion is interrupted intermittently by edge impacts. The experiments were carried out for pris... We study experimentally and theoretically the planar dynamics of purely rolling prisms on a rough ramp, where the rolling motion is interrupted intermittently by edge impacts. The experiments were carried out for prisms made of different materials and having different geometries. We found that the angular velocities of the rolling prisms are material-independent, but they change significantly with their geometry. We modelled the dynamics of edge impacts by considering a socalled detachment front propagating across the contact interface. The detachment front represents the moving boundary between a detached region and a stress region that coexist within the interface plane. The theoretical analysis indicates that the detachment front can be characterized by a scale number, whose value converges to 0.4050 for prisms having large number of edges. A new jump rule for edge impacts is then developed, by which we can accurately reproduce the experimental observations, and explain why the motion of the prism is material-independent. 展开更多
关键词 surface impact Jump rule Experiments
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Two-year measurements of surface ozone at Dangxiong,a remote highland site in the Tibetan Plateau 被引量:6
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作者 Weili Lin Xiaobin Xu +3 位作者 Xiangdong Zheng Jaxi Dawa Ciren Baima Jin Ma 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2015年第5期133-145,共13页
Measurements of surface O3 and carbon monoxide(CO) were made from September 2009 to August 2011 at Dangxiong(30.48°N, 91.10°E, 4187 m a.s.l.), a remote highland site in a southern valley of the Nyainq... Measurements of surface O3 and carbon monoxide(CO) were made from September 2009 to August 2011 at Dangxiong(30.48°N, 91.10°E, 4187 m a.s.l.), a remote highland site in a southern valley of the Nyainqêntanglha Mountains in the Tibetan Plateau, China. The monthly mean O3 mixing ratio ranged from 29.1 to 51.4 ppb, with an average of 38.5 ppb, and the maximum value was observed in May. The average diurnal cycle of O3 concentration showed a minimum in early morning and a maximum in the afternoon, with a broader "high platform" from the late morning to the late afternoon, and resembled that of surface wind speed. The concentration of surface O3 was highly significantly correlated with tropospheric column O3 over the regions surrounding Dangxiong and with that of surface O3 observed at a site north of the Nyainqêntanglha Mountains, suggesting a good regional representativeness of surface O3 at Dangxiong. In the afternoon when stronger winds blew, surface air showed distinct features of free-atmospheric air, with higher O3, lower CO, and lower relative humidity(RH). The negative O3-CO and O3-RH correlations in most months indicate a significant influence of air masses from the free troposphere. Trajectory analysis suggests that air masses originating from the south of the site make a negative net contribution to surface O3 and a positive contribution to CO and humidity, and those from the northwest sector contribute conversely to the respective quantities. 展开更多
关键词 surface ozone Tibetan Plateau impact of transport and vertical mixing
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Exploring the effects of angle of incidence on stabbing resistance in advanced protective textiles:Novel experimental framework and analysis
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作者 Mulat Alubel Abtew François Boussu Irina Cristian 《Defence Technology(防务技术)》 2025年第2期67-82,共16页
Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and... Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and performance of different types of protective textiles.Three distinct structures of 3D woven textiles and 2D plain weave fabric made with similar high-performance fiber and areal density were designed and manufactured to be tested.Two samples,one composed of a single and the other of 4-panel layers,from each fabric type structure,were prepared,and tested against stabbing at[0○],[22.5○],and[45○]angle of incidence.A new stabbing experimental setup that entertained testing of the specimens at various angles of incidence was engineered and utilized.The stabbing bench is also equipped with magnetic sensors and a UK Home Office Scientific Development Branch(HOSDB)/P1/B sharpness engineered knives to measure the impact velocity and exerted impact energy respectively.A silicon compound was utilized to imprint the Back Face Signature(BFS)on the backing material after every specimen test.Each silicon print was then scanned,digitized,and precisely measured to evaluate the stab response and performance of the specimen based on different performance variables,including Depth of Trauma(DOT),Depth of Penetration(DOP),and Length of Penetration(LOP).Besides,the post-impact surface failure modes of the fabrics were also measured using Image software and analyzed at the microscale level.The results show stab angle of incidence greatly influences the stab response and performance of protective textiles.The outcome of the study could provide not only valuable insights into understanding the stab response and capabilities of protective textiles under different angle of incidence,but also provide valuable information for protective textile manufacturer,armor developer and stab testing and standardizing organizations to consider the angle of incidence while developing,testing,optimizing,and using protective textiles in various applications. 展开更多
关键词 2D/3D woven fabrics impact protective fabric Drop tower perforation test Stab resistance testing protocol Angle of incidence Multi-layer panels Soft body armor impact surface damage
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Microstructure and mechanical properties of TC4 titanium alloy K-TIG welded joints 被引量:19
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作者 Shu-wan CUI Yong-hua SHI Cheng-shi ZHANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第2期416-425,共10页
The 12 mm-thick Ti−6Al−4V(TC4)titanium alloy plates were welded using keyhole tungsten inert gas(K-TIG)welding at various heat inputs.The microstructure,grain boundary(GB)characteristics and mechanical properties of t... The 12 mm-thick Ti−6Al−4V(TC4)titanium alloy plates were welded using keyhole tungsten inert gas(K-TIG)welding at various heat inputs.The microstructure,grain boundary(GB)characteristics and mechanical properties of the weld metal zone(WMZ)were analyzed.The test results show that the K-TIG welds are well formed,and no obvious defects are observed when the heat input is 2.30−2.62 kJ/mm.When the heat input gradually increases,αlaths increase in length,andα′phase and residualβphase are reduced.The electron backscatter diffraction(EBSD)test results indicate that the high-angle GB proportion in the WMZ increases with the increase of heat input.The tensile strength of the WMZ gradually decreases and the elongation of the WMZ increases when the heat input increases from 2.30 to 2.62 kJ/mm.The impact toughness of the WMZ increases as the heat input increases. 展开更多
关键词 K-TIG welding heat input α′phase high-angle grain boundary Charpy impact fracture surface
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TRACKING METHODS FOR FREE SURFACE AND SIMULATION OF A LIQUID DROPLET IMPACTING ON A SOLID SURFACE BASED ON SPH 被引量:4
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作者 LI Da-ming XU Ya-nan +2 位作者 LI Ling-ling LU Hui-jiao BAI Ling 《Journal of Hydrodynamics》 SCIE EI CSCD 2011年第4期447-456,共10页
With some popular tracking methods for free surface, simulations of several typical examples are carried out under various flow field conditions. The results show that the Smoothed Particle Hydrodynamics (SPH) metho... With some popular tracking methods for free surface, simulations of several typical examples are carried out under various flow field conditions. The results show that the Smoothed Particle Hydrodynamics (SPH) method is very suitable in simulating the flow problems with a free surface. A viscous liquid droplet with an initial velocity impacting on a solid surface is simulated based on the SPH method, and the surface tension is considered by searching the free surface particles, the initial impact effect is considered by using the artificial viscosity method, boundary virtual particles and image virtual particles are introduced to deal with the boundary problem, and the boundary defect can be identified quite well. The comparisons of simulated results and experimental photographs show that the SPH method can not only exactly simulate the spreading process and the rebound process of a liquid droplet impacting on a solid surface but also accurately track the free surface particles, simulate the free-surface flow and determine the shape of the free surface due to its particle nature. 展开更多
关键词 Smoothed Particle Hydrodynamics (SPH) method viscous liquid droplet impacting on a solid surface free surface
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IMPACTS OF SURFACE FRICTION AND OROGRAPHICAL FORCING ON THE EAST ASIA COASTAL CYCLOGENESIS
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作者 陈受钧 《Acta meteorologica Sinica》 SCIE 1989年第1期102-107,共6页
Some numerical simulations from real data were carried out to examine the impacts of surface friction and orographic forcing on the East Asia coastal cyclogenesis.The results show that the decreasing of the surface fr... Some numerical simulations from real data were carried out to examine the impacts of surface friction and orographic forcing on the East Asia coastal cyclogenesis.The results show that the decreasing of the surface friction over the ocean is essential for the cyclone development and the mechanical forcing of Qinghai-Xizang Plateau acts a damping effect in the initial stage of the cyclone. 展开更多
关键词 EVP impactS OF surface FRICTION AND OROGRAPHICAL FORCING ON THE EAST ASIA COASTAL CYCLOGENESIS
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Simulations of helicopter ditching using smoothed particle hydrodynamics 被引量:4
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作者 G.Oger A.Vergnaud +9 位作者 B.Bouscasse J.Ohana M.Abu Zarim M.De Leffe A.Bannier L.Chiron Y.Jus M.Gamier S.Halbout D.Le Touze 《Journal of Hydrodynamics》 SCIE EI CSCD 2020年第4期653-663,共11页
The present work has been performed in the context of the European H2020 project increased SAfety and Robust certification for ditching of Aircrafts and Helicopters(SARAH)dedicated to improving the safety during aircr... The present work has been performed in the context of the European H2020 project increased SAfety and Robust certification for ditching of Aircrafts and Helicopters(SARAH)dedicated to improving the safety during aircraft ditching,together with a better understanding of the physics involved during those crucial events.Both numerical and experimental aspects are explored during this project.The present study focuses on the application of the smoothed particle hydrodynamics(SPH)method to the simulation of helicopter ditching,as this method has proved to be particularly adapted to free surface impact cases.Simulations are performed for three different impact configurations,for which the numerical solutions are compared with the experimental results(forces and kinematics)obtained at the wave basin of Ecole Centrale Nantes on a mock-up shape provided by Airbus Helicopters.Elements of sensitivity analysis are also provided when needed,to assess the role of some parameters involved in the helicopter behavior and the fluid pressure forces exerted during the impact. 展开更多
关键词 Helicopter ditching smoothed particle hydrodynamics(SPH) Free surface impact wave impact numerical vs experimental solutions
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