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卓越音频技术缔造智慧广电视听新世界--FraunhoferIIS在CCBN成功展示了下一代广播电视音频标准和VR音频解决方案
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《有线电视技术》 2017年第4期27-28,共2页
2017年3月23日,来自德国的音频及媒体技术研究机构FraunhoferIIS在2017年中国国际广播电视信息网络展览会(CCBN)上展示了成功被ATSC3.0和DVB数字电视标准采纳的MPEG-H电视音频解决方案,以及为VR和移动设备设备带来最佳沉浸式声音体... 2017年3月23日,来自德国的音频及媒体技术研究机构FraunhoferIIS在2017年中国国际广播电视信息网络展览会(CCBN)上展示了成功被ATSC3.0和DVB数字电视标准采纳的MPEG-H电视音频解决方案,以及为VR和移动设备设备带来最佳沉浸式声音体验的FraunhoferCingo技术和能够显著简化VR沉浸式声音制作流程的CingoComposer软件。 展开更多
关键词 中国国际广播电视信息网络展览会 音频标准 CCBN 音频技术 VR poser软件 世界 视听
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全新的Fraunhofer电视节目交互和沉浸式音频系统
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作者 Albert Heuberger 《广播与电视技术》 2015年第A02期75-79,共5页
如今的电视观众可以通过各种各样的设备获取资讯内容,人们越来越多的关注电视声音的无干扰以及沉浸效果。与此同时,消费者更加习惯于新媒体所带来的更强的互动性以及更具个性化的服务。
关键词 音频系统 电视节目 沉浸式 交互 电视观众 电视声音 无干扰 个性化
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Impact of classification granularity on interdisciplinary performance assessment of research institutes and organizations 被引量:1
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作者 Jiandong Zhang Sonia Gruber Rainer Frietsch 《Journal of Data and Information Science》 2025年第2期61-79,共19页
Purpose:Interdisciplinary research has become a critical approach to addressing complex societal,economic,technological,and environmental challenges,driving innovation and integrating scientific knowledge.While interd... Purpose:Interdisciplinary research has become a critical approach to addressing complex societal,economic,technological,and environmental challenges,driving innovation and integrating scientific knowledge.While interdisciplinarity indicators are widely used to evaluate research performance,the impact of classification granularity on these assessments remains underexplored.Design/methodology/approach:This study investigates how different levels of classification granularity-macro,meso,and micro-affect the evaluation of interdisciplinarity in research institutes.Using a dataset of 262 institutes from four major German non-university organizations(FHG,HGF,MPG,WGL)from 2018 to 2022,we examine inconsistencies in interdisciplinarity across levels,analyze ranking changes,and explore the influence of institutional fields and research focus(applied vs.basic).Findings:Our findings reveal significant inconsistencies in interdisciplinarity across classification levels,with rankings varying substantially.Notably,the Fraunhofer Society(FHG),which performs well at the macro level,experiences significant ranking declines at meso and micro levels.Normalizing interdisciplinarity by research field confirmed that these declines persist.The research focus of institutes,whether applied,basic,or mixed,does not significantly explain the observed ranking dynamics.Research limitations:This study has only considered the publication-based dimension of institutional interdisciplinarity and has not explored other aspects.Practical implications:The findings provide insights for policymakers,research managers,and scholars to better interpret interdisciplinarity metrics and support interdisciplinary research effectively.Originality/value:This study underscores the critical role of classification granularity in interdisciplinarity assessment and emphasizes the need for standardized approaches to ensure robust and fair evaluations. 展开更多
关键词 Interdisciplinarity Paper-level classification system Organization evaluation
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A review on collisions between drones and aerostructures——Experimental studies,numerical simulation,and regulation
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作者 Michael May Tim Strohbach 《Defence Technology(防务技术)》 2025年第9期1-29,共29页
The increasing presence of drones seen on the battlefields in modern conflicts poses new threats to manned military aircraft or rotorcraft.In order to assess this potential threat,this manuscript first summarizes all ... The increasing presence of drones seen on the battlefields in modern conflicts poses new threats to manned military aircraft or rotorcraft.In order to assess this potential threat,this manuscript first summarizes all confirmed and suspected collisions between drones and aerostructures and the damage resulting from these collisions.Furthermore,this manuscript reviews experimental and numerical investigations on collision of drones with aerostructures.Additionally,some light is shed onto current regulation for drone operations intended to avoid collisions between drones and aircraft.Whilst these regulatory measures can prevent commercial aircraft to collide with drones,the authors believe that there is an inherent threat for civil and military rotorcraft due to their structural design and the fact that it is not possible to completely separate the airspace between drone operations and rotorcraft operations,in particular in the context of rescue missions in an urban or hostile environment.Furthermore,the stealth capability of 5th generation fighters may be compromised by damage suffered from collision with drones. 展开更多
关键词 DRONE UAV COLLISION Impact Aircraft ROTORCRAFT
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Index-adapting cladding light stripper for high-power thulium fiber lasers
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作者 Tilman Lühder Till Walbaum Thomas Schreiber 《Advanced Photonics Nexus》 2025年第6期45-55,共11页
Cladding light strippers(CLSs)are essential components for high-power monolithic fiber laser systems.Because they allow for bending of the fiber,which leads to an excellent stripping efficiency of light with a low ray... Cladding light strippers(CLSs)are essential components for high-power monolithic fiber laser systems.Because they allow for bending of the fiber,which leads to an excellent stripping efficiency of light with a low ray angle,refractive index-based CLSs have an advantage over the commonly used alternative approaches.However,conventional high-index CLSs overheat at relatively low input power as the maximum temperature,located in a hot-spot,increases linearly with the input power.This applies particularly to CLSs in thulium-based fiber systems,where very low power can already lead to extreme heat generation due to the high cladding material absorption around 2μm.Here,we investigate materials with a highly negative thermooptical coefficient combined with a refractive index closely above glass to distribute the stripped power and heat uniformly along an increased fiber length.Analyzing multiple CLS geometries for fiber diameters of 125 and 400μm,we show record-high maximum input powers for single-material CLSs of 21.8 W for the signal(2039 nm)and 675 W for the pump wavelength(793 nm).Transmitting excess light instead of overheating,this wavelength-adaptable self-protecting CLS concept is fast to apply onsite in the lab and reaches stripping efficiencies of>40 dB in the bent version. 展开更多
关键词 THULIUM cladding light stripper optical gel thermo-optical coefficient fiber laser
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Pressure and temperature effects resulting from impact onto materials of different reactivity
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作者 Andreas Heine Matthias Wickert 《Defence Technology(防务技术)》 2025年第2期221-230,共10页
The pressure and temperature increase resulting from the impact of different threats onto target materials is analyzed with a unified laboratory-scale setup.This allows deriving qualitative information on the occurrin... The pressure and temperature increase resulting from the impact of different threats onto target materials is analyzed with a unified laboratory-scale setup.This allows deriving qualitative information on the occurring phenomenology as well as quantitative statements about the relative effects sizes as a function of target material and threat.The considered target materials are steel,aluminum,and magnesium.As threats,kinetic energy penetrator,explosively formed projectile,and shaped charge jet are used.For the investigated combinations,the measured overpressures vary by a factor of up to 5 for a variation of the material,by a factor of up to 7 for a variation of the threat,and by a factor larger than 15for a simultaneous variation of both.The obtained results as well as the experimental approach are relevant for the basic understanding of impact effects and risks due to material reactivity.The paper combines two main aims.Firstly,to provide a summary of own prior work in a coherent journal article and,secondly,to review and discuss these earlier results with a new perspective. 展开更多
关键词 Impact effects PRESSURE TEMPERATURE Risk assessment Material reactivity
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The hydrodynamic RAM effect:Review of historic experiments,model developments and simulation
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作者 Georg A.Heilig Michael May 《Defence Technology(防务技术)》 2025年第2期150-178,共29页
The Hydrodynamic Ram(HRAM)effect occurs when a high kinetic energy projectile penetrates a fluid filled area,e.g.,a liquid filled tank.The projectile transfers its momentum and kinetic energy to the fluid,what causes ... The Hydrodynamic Ram(HRAM)effect occurs when a high kinetic energy projectile penetrates a fluid filled area,e.g.,a liquid filled tank.The projectile transfers its momentum and kinetic energy to the fluid,what causes a sudden,local pressure rise,further expanding as primary shock wave in the fluid and developing a cavity.It is possible that the entire tank ruptures due to the loads transferred through the fluid to its surrounding structure.In the past decades,additionally to experimental investigations,HRAM has been studied using various computational approaches particularly focusing on the description of the Fluid-Structure Interaction(FSI).This article reviews the published experimental,analytical and numerical results and delivers a chronological overview since the end of World War II.Furthermore,HRAM mitigation measures are highlighted,which have been developed with the experimental,analytical and numerical toolboxes matured over the past 80 years. 展开更多
关键词 Fluid-structure-interaction(FSI) Euler-Lagrange-Coupling Hydrodynamic RAM effect HRAM
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Comparison of Different ANFIS Models for the Condition Monitoring of a Rack and Pinion Contact Using Methods of Explainable Artificial Intelligence
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作者 Tobias Biermann Jonathan Millitzer Karsten Schmidt 《Journal of Dynamics, Monitoring and Diagnostics》 2025年第3期148-159,共12页
This paper investigates the use of explainable artificial intelligence(XAI)and trustworthy artificial intelligence(TAI)methods for condition monitoring on a laser cutting machine.The focus is on the analysis of the ra... This paper investigates the use of explainable artificial intelligence(XAI)and trustworthy artificial intelligence(TAI)methods for condition monitoring on a laser cutting machine.The focus is on the analysis of the rack and pinion contact with wear being predicted by four differently derived adaptive-network-based fuzzy inference system(s)(ANFIS)models.Using both model-agnostic and model-specific parameters integrated in a weighted evaluation framework,the models are evaluated with respect to the effectiveness of explanations.This framework is based on the observation of the outputs of the individual layers of ANFIS,also focusing on aspects of two multivalued logics,namely fuzzy logic and support logic.The results show that the introduced weighted evaluation framework makes it possible to quantify the explainability of the individual models in terms of XAI and TAI.Finally,a preselection of a model for predicting the wear of the rack and pinion contact can be made. 展开更多
关键词 ANFIS condition monitoring rack and pinion contact XAI
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Feasibility study on the suitability of dielectric barrier discharge plasma treatment of desert sand for concrete production purposes
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作者 Yorick FENNER Martin BELLMANN +1 位作者 Andreas TUMMEL Christoph GERHARD 《Plasma Science and Technology》 2025年第1期111-117,共7页
Due to the continuously increasing building and construction industry,sand has become one of the most questioned raw materials worldwide.However,the available amount of sand suitable for concrete production is orders ... Due to the continuously increasing building and construction industry,sand has become one of the most questioned raw materials worldwide.However,the available amount of sand suitable for concrete production is orders of magnitude lower that the demand and consumption.Even though desert sand is sufficiently available,it is not usable for realizing stable concrete due to its surface shape.Against this background,the suitability of energy-efficient‘cold'dielectric barrier discharge plasma operated at atmospheric pressure for improving the properties of concrete produced from desert sand was investigated in this contribution.It is shown that such plasma treatment allows for a certain roughening and re-shaping of sand grains.As a result,the mass flow of treated sand is decreased due to an improved wedging of sand grains.This leads to a certain increase in compressive strength of concrete samples.Even though this increase is marginal,the suitability of the applied type of plasma for modification of the geometry and surface chemistry of sand grains was proven,showing its basic potential for the treatment and preconditioning of sand used for concrete,mortar or plastering. 展开更多
关键词 plasma treatment atmospheric pressure plasma SAND CONCRETE surface roughening mass flow compressive strength
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Coaxial method to investigate broadband dielectric properties of rocks over the 5 Hz to 3 GHz frequency range
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作者 Thierry Bore Yu-Jen Shen +5 位作者 Mehdi Serati Yoann Pascal Muhannad Al Kalbani Alexander Scheuermann Norman Wagner Markus Loewer 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第11期6837-6852,共16页
In this paper,we present a novel approach to study the electrical properties of intact rock by combining impedance and vector network analyzer measurements in the frequency range from 5 Hz to 3 GHz.For the firsttime,t... In this paper,we present a novel approach to study the electrical properties of intact rock by combining impedance and vector network analyzer measurements in the frequency range from 5 Hz to 3 GHz.For the firsttime,this study enables electrical characterization of the exact same rock sample over nine orders of magnitude in frequency range,utilizing a coaxial cell apparatus with specificallyprepared rock samples.Three types of rocks(basalt,sandstone and granite)with low to intermediate porosity(12.24%,16.9%and 7.49%,respectively)were characterized at varying saturation levels.The relaxation behavior of the samples was quantifiedusing an advanced phenomenological model incorporating both the dielectric constant and electrical conductivity in the form of Debye and Cole-Cole representations.Across the frequency range,three distinct relaxation processes were identified:a high-frequency water process and two interfacial processes related to interactions between the aqueous pore solution and mineral particles(membrane relaxation and Maxwell-Wagner effects).Additionally,an apparent direct current conductivity was observed.This comprehensive broadband analysis represents a further step toward the in situ characterization of rocks using electromagnetic fieldmeasurement methods and demonstrates advancements in both methodology and understanding of rock properties compared to existing studies. 展开更多
关键词 Dielectric spectroscopy ROCKS Coaxial transmission line Complex permittivity Complex conductivity
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Single-sideband modulation for dynamically reconfigurable multiwavelength interferometry
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作者 Leonard Voßgrag Annelie Schiller +4 位作者 Tobias Seyler Markus Fratz Alexander Bertz Daniel Carl Ingo Breunig 《Advanced Photonics Nexus》 2025年第4期119-127,共9页
Single-wavelength interferometry achieves high resolution for smooth surfaces but struggles with rough industrially relevant ones due to limited unambiguous measuring range and speckle effects.Multiwavelength interfer... Single-wavelength interferometry achieves high resolution for smooth surfaces but struggles with rough industrially relevant ones due to limited unambiguous measuring range and speckle effects.Multiwavelength interferometry addresses these challenges using synthetic wavelengths,enabling a balance between extended measurement range and resolution by combining several synthetic wavelengths.This approach holds immense potential for diverse industrial applications,yet it remains largely untapped due to the lack of suitable light sources.Existing solutions are constrained by limited flexibility in synthetic-wavelength generation and slow switching speeds.We demonstrate a light source for multiwavelength interferometry based on electro-optic single-sideband modulation.It reliably generates synthetic wavelengths with arbitrary values from centimeters to meters and switching time below 30 ms.This breakthrough paves the way for dynamic reconfigurable multiwavelength interferometry capable of adapting to complex surfaces and operating efficiently even outside laboratory settings.These capabilities unlock the full potential of multiwavelength interferometry,offering unprecedented flexibility and speed for industrial and technological applications. 展开更多
关键词 digital holography electro-optic modulation INTERFEROMETRY
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Application of a Regional Data Set of the Housing Sector for Hydrogen Storage-Supported Energy System Planning
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作者 Steffen Schedler Michael Bareev-Rudy +1 位作者 Stefanie Meilinger Tanja Clees 《Energy Engineering》 2025年第5期1755-1770,共16页
Germany aims to achieve a national climate-neutral energy system by 2045.The residential sector still accounts for 29%of end energy consumption,with 74%attributed to the direct use of fossil fuels for heating and hot ... Germany aims to achieve a national climate-neutral energy system by 2045.The residential sector still accounts for 29%of end energy consumption,with 74%attributed to the direct use of fossil fuels for heating and hot water.In order to reduce fossil energy use in the household sector,great efforts are being made to design new energy concepts that expand the use of renewable energies to supply electricity andheat.Onepossibility is toconvertparts of the natural gas grid to a hydrogen-based gas grid to deliver and store energy for urban quarters of buildings,especially with older building stock where electrification of heat via heat pumps is difficult due to technical,acoustical,and economic reasons.A comprehensive dataset was generated by a bottom-up analysis with open governmental and statistical data to determine regional building types regarding energy demand,solar potential,and existing grid infrastructure.The buildings’connections to the electricity,gas,and district heating networks are considered.From this,a representative sample dataset was chosen as input for a newly developed energy system model based on energy flow simulation.The model simulates the interaction of hydrogen generation(HG)(from excess solar energy by electrolysis),storage in a metal-hydride storage(MHS)tank,and hydrogen use in a connected fuel cell(FC),forming a local PVPtGtHP(Photovoltaic Power-to-Gas-to-Heat-and-Power)network.Next to the seasonal hydrogen storage path(HSP),a battery will complete the system to forma hybrid energy storage system(HESS).Paired with seasonal time series for PV power,electricity and heat demand,and a model for connection to grid infrastructure,the simulation of different hydrogen applications and MHS placements aims to analyze operating times and energy share of the systems’equipment and existing infrastructure.The method to obtain the data set together with the simulationmodel presented can be used by energy planners for cities,communities,and building developers to analyze the potentials of a quarter or region and plan a transition towards a more energy-efficient and sustainable energy system. 展开更多
关键词 Hydrogen storage hybrid energy storage system simulation housing sector energy share
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Ensemble modelling for smart conservation strategies for forest reptile species at their range edges in Europe amidst climate change
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作者 Oksana Nekrasova Mihails Pupins +5 位作者 Volodymyr Tytar AndrisČeirāns Oleksii Marushchak ArtursŠkute Kathrin Theissinger Jean-Yves Georges 《Geography and Sustainability》 2025年第2期97-107,共11页
Reptile fauna should be considered a conservation objective,especially in respect of the impacts of climate change on their distribution and range’s dynamics.Investigating the environmental drivers of reptile species... Reptile fauna should be considered a conservation objective,especially in respect of the impacts of climate change on their distribution and range’s dynamics.Investigating the environmental drivers of reptile species richness and identifying their suitable habitats is a fundamental prerequisite to setting efficient long-term conservation measures.This study focused on geographical patterns and estimations of species richness for herpetofauna widely spread Z.vivipara,N.natrix,V.berus,A.colchica,and protected in Latvia C.austriaca,E.orbicularis,L.agilis inhabiting northern(model territory Latvia)and southern(model territory Ukraine)part of their European range.The ultimate goal was to designate a conservation network that will meet long-term goals for survival of the target species in the context of climate change.We used stacked species distribution models for creating maps depicting the distribution of species richness under current and future(by 2050)climates for marginal reptilepopulations.Using cluster analysis,we showed that this herpeto-complex can be divided into“widespread species”and“forest species”.For all forest species we predicted a climate-driven reduction in their distribution range both North(Latvia)and South(Ukraine).The most vulnerable populations of“forest species”tend to be located in the South of their range,as a consequence of northward shifts by 2050.By 2050 the greatest reduction in range is predicted for currently widely spread Z.vivipara(by 1.4 times)and V.berus(by 2.2 times).In terms of designing an effective protected-area network,these results permit to identify priority conservation areas where the full ensemble of selected reptile species can be found,and confirms the relevance of abioticmulti-factor GIS-modelling for achieving this goal. 展开更多
关键词 Edge of area Stacked species distribution models Suitable habitats Priority conservation areas
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1961-2015年内蒙古高原内陆河东部流域极端降水时空变化特征分析 被引量:20
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作者 李玮 段利民 +4 位作者 刘廷玺 格日勒吐 高瑞忠 Buren Scharaw 于长翔 《资源科学》 CSSCI CSCD 北大核心 2017年第11期2153-2165,共13页
掌握极端降水时空变化特征对流域水文生态等相关研究具有重要的指导意义。本文以内蒙古高原内陆河东部流域1961—2015年0.5°×0.5°降水格点数据为基础,采用M-K法、主成分分析和相关分析等气候诊断法,对6个极端降水指数的... 掌握极端降水时空变化特征对流域水文生态等相关研究具有重要的指导意义。本文以内蒙古高原内陆河东部流域1961—2015年0.5°×0.5°降水格点数据为基础,采用M-K法、主成分分析和相关分析等气候诊断法,对6个极端降水指数的时空变化特征进行分析,并研究了极端降水事件对ENSO事件的响应。结果表明:1961—2015年内蒙古高原中部内陆河流域极端降水指数的年际变化趋势总体以下降为主,其中CDD(连续无雨日数)下降的区域占整个流域的91%,除CDD外其余指数均呈"东高西低"的空间分布格局,SDII(雨强)均值介于(3.8~5.3)mm/d之间,空间差异较小;R95P(强降水量)在强降水事件中具有0.96的最高载荷,对该事件具有指示作用;当发生厄尔尼诺事件时,流域持续干旱情况加剧,出现拉尼娜现象时,流域易发生洪涝灾害。 展开更多
关键词 内陆河流域 极端降水 时空变化 ENSO事件 内蒙古高原
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选区激光熔化制备TiC_x/Ti纳米复合材料的致密化及显微组织 被引量:7
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作者 李闯 顾冬冬 +1 位作者 沈以赴 孟广斌 《中国有色金属学报》 EI CAS CSCD 北大核心 2011年第7期1554-1561,共8页
利用选区激光熔化(SLM)工艺制备TiCx增强Ti基纳米复合材料试件;通过X射线衍射仪和场发射扫描电子显微镜等研究激光线能量密度η(激光功率与扫描速率之比)对选区激光熔化试件的致密化过程、物相及显微组织的影响规律,并讨论激光快速熔凝... 利用选区激光熔化(SLM)工艺制备TiCx增强Ti基纳米复合材料试件;通过X射线衍射仪和场发射扫描电子显微镜等研究激光线能量密度η(激光功率与扫描速率之比)对选区激光熔化试件的致密化过程、物相及显微组织的影响规律,并讨论激光快速熔凝过程中TiC0.625层片状纳米结构的形成机理。结果表明:当激光线能量密度η为1 100 J/m时,成形试件的致密度可达95.6%;其内部增强体为层片状纳米结构,平均厚度为54 nm,且在Ti基体中分布均匀。增强相TiCx以亚化学计量TiC0.625形式存在,具有立方晶体结构。 展开更多
关键词 选区激光熔化 线能量密度 致密度 显微组织 TiC0.625
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半干旱草原型流域径流变化特征及其影响因子定量分析 被引量:9
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作者 段利民 李玮 +2 位作者 刘廷玺 罗艳云 Buren Scharaw 《干旱区资源与环境》 CSSCI CSCD 北大核心 2017年第10期125-130,共6页
研究引起径流变化的主要驱动因子对流域水文水资源与生态相关研究具有重要的指导意义。以典型草原型流域-锡林河流域1970-2014年径流及气象数据为基础,采用Mann-Kendall法、弹性系数法定量分析了气候变化及人类活动对径流变化的贡献程... 研究引起径流变化的主要驱动因子对流域水文水资源与生态相关研究具有重要的指导意义。以典型草原型流域-锡林河流域1970-2014年径流及气象数据为基础,采用Mann-Kendall法、弹性系数法定量分析了气候变化及人类活动对径流变化的贡献程度。结果表明:近45a来锡林河流域年径流量呈显著下降的趋势,在1979、1986和1998年发生突变。1980-1986年人类活动对径流减少的贡献率为46.57%;1987-1998年人类活动对径流增加的贡献率高达91.46%,气候变化的贡献率仅为8.54%;1999-2014年人类活动对径流减少的贡献率为66.16%。整体而言,人类活动是锡林河流域径流变化的主要驱动力。 展开更多
关键词 草原型流域 径流 气候变化及人类活动 MANN-KENDALL法 弹性系数法
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锡林河流域植被叶面积指数时空变化特征及其对地形因子的响应 被引量:15
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作者 段利民 李玮 +3 位作者 罗艳云 刘廷玺 Buren Scharaw 于长翔 《水土保持研究》 CSCD 北大核心 2019年第3期224-231,共8页
为了摸清欧亚大陆大草原重要的组成部分锡林河流域在外界环境和人类活动干扰下植被的时空变异规律及其与地形因子的响应关系,利用遥感影像数据及基于大气阻抗植被指数(ARVI)的统计模型,反演了1985—2015年4个典型代表年份的LAI,从长时... 为了摸清欧亚大陆大草原重要的组成部分锡林河流域在外界环境和人类活动干扰下植被的时空变异规律及其与地形因子的响应关系,利用遥感影像数据及基于大气阻抗植被指数(ARVI)的统计模型,反演了1985—2015年4个典型代表年份的LAI,从长时间尺度上分析了LAI的时空变化特征以及地形因子对其空间分布格局的影响。结果表明:近30 a,锡林河流域LAI总体呈上升趋势,多年平均值为0.8~1.5,从上游至下游逐渐降低。植被恢复状况空间差异明显,主要发展态势为恢复。LAI在0.78~0.82,0.82~0.86所占面积比例随着海拔、坡度的升高而降低,在东南方向上的面积占比大于其他方向;LAI在0.92~1.5,1.5~3.0所占面积比例随着海拔、坡度的升高而增大,在西、西南方向上的面积占比大于其他方向。高程对LAI的直接影响效应为0.438,远大于坡度和坡向对LAI的影响。本研究可为草原型流域陆面过程及生态水文研究提供理论基础和科学依据,对于天然生态系统的健康维持、退化生态系统的恢复重建等也具有一定的参考价值。 展开更多
关键词 植被指数 地形因子 转移矩阵 趋势分析
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高沉积率激光金属沉积Inconel 718的孔隙率控制 被引量:7
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作者 仲崇亮 付金宝 +1 位作者 丁亚林 Andres Gasser 《光学精密工程》 EI CAS CSCD 北大核心 2015年第11期3005-3011,共7页
为降低高沉积率激光金属沉积(Laser Metal Deposition,LMD)工艺中材料的孔隙率,研究了以镍基高温合金Inconel 718(IN718)为粉末沉积材料的高沉积率LMD工艺中主要工艺参数对材料孔隙率的影响,以及通过调整工艺参数降低材料孔隙率的方法... 为降低高沉积率激光金属沉积(Laser Metal Deposition,LMD)工艺中材料的孔隙率,研究了以镍基高温合金Inconel 718(IN718)为粉末沉积材料的高沉积率LMD工艺中主要工艺参数对材料孔隙率的影响,以及通过调整工艺参数降低材料孔隙率的方法。以目标沉积率为2kg/h的LMD工艺为基础,通过参数固化和分离的手段开展了高沉积率LMD的镀层实验,研究了主要工艺参数即激光功率、扫描速度及送粉量对LMD镀层材料孔隙率的影响,分析了不同参数下各镀层的横截面孔隙率及镀层孔隙率。实验显示:当激光功率从1 440 W增加到4 214 W时,镀层材料的孔隙率从约1.5%降低至0.02%左右;当扫描速度为500mm/min至5 000mm/min时,镀层材料孔隙率始终保持为0.07%至0.18%左右;当送粉量从0.64kg/h增加至6.48kg/h时,镀层材料孔隙率从约0.01%增加至0.84%左右。可见在高沉积率LMD工艺中,扫描速度对材料孔隙率无明显影响,而提高激光功率、限制送粉量均可有效降低LMD材料孔隙率,提高横截面孔隙率的一致性。 展开更多
关键词 激光加工 激光金属沉积 增材制造 孔隙率 INCONEL 718
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晶体塑性模型描述多晶体循环加载中的Bauschinger效应 被引量:2
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作者 郑黎 张士宏 +2 位作者 何维均 宋鸿武 Dirk Helm 《材料科学与工艺》 EI CAS CSCD 北大核心 2014年第6期78-84,共7页
为了研究循环加载过程中织构对多晶材料Baushinger效应的影响,利用经典晶体塑性模型及含随动硬化的晶体塑性模型模拟AA6104铝合金循环加载力学行为.研究了多晶体中晶粒取向差异对材料宏观塑性行为的影响.详细分析了经典晶体塑性模型可... 为了研究循环加载过程中织构对多晶材料Baushinger效应的影响,利用经典晶体塑性模型及含随动硬化的晶体塑性模型模拟AA6104铝合金循环加载力学行为.研究了多晶体中晶粒取向差异对材料宏观塑性行为的影响.详细分析了经典晶体塑性模型可描述多晶体循环加载Bauschinger效应机理,定量分析了多晶有限元模型中晶体取向差异对模拟结果的影响.结果表明多晶体中由于晶粒取向差异而造成的晶粒间相互作用力使得多晶体模型宏观卸载时晶粒内的残余应力是产生Bauschinger效应的主要原因,采用含随动硬化的晶体塑性模型能够较好地模拟具有织构的AA6014铝合金的循环加载过程. 展开更多
关键词 Bauschinger效应 循环加载 晶体塑性模型 数值模拟 随动硬化
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手动式电磁定位及图像导航的短径癌症放射治疗系统 被引量:5
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作者 陈为 Georgios Sakas 彭群生 《计算机辅助设计与图形学学报》 EI CSCD 北大核心 2002年第9期870-876,共7页
提出一个用于高剂量短径癌症放射治疗的手动式电磁定位及图像导航系统 .该系统主要由 4个模块组成 :预处理、术前规划、术内导航和术后计划 .它们分别对应高剂量短径癌症放射治疗的 4个流程 :在术前规划阶段 ,用户可交互地设计探针放置... 提出一个用于高剂量短径癌症放射治疗的手动式电磁定位及图像导航系统 .该系统主要由 4个模块组成 :预处理、术前规划、术内导航和术后计划 .它们分别对应高剂量短径癌症放射治疗的 4个流程 :在术前规划阶段 ,用户可交互地设计探针放置位置以及三维重建病灶轮廓 ;在手术进行过程中 ,六自由度的电磁式定位技术实时而精确地跟踪探针位置 ,高质量的可视化技术指引医生完成手术探针放置任务 ;手术探针全部放置完毕后 ,术后计划模板计算剂量分布并利用后装机设备进行放射治疗 .初步实验表明 ,计算机辅助的探针定位比手工定位精度提高 2~ 3倍 ,手术时间减少 5倍以上 。 展开更多
关键词 手动式电磁定位 图像导航 短径癌症放射治疗系统 体绘制 医学可视化 肿瘤
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