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Recent Progress in Numerical Atmospheric Modeling in China 预览
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作者 Rucong YU Yi ZHANG +4 位作者 Jianjie WANG Jian LI Haoming CHEN Jiandong GONG Jing CHEN 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第9期938-960,共23页
This review summarizes the scientific and technical progress in atmospheric modeling in China since 2011,including the dynamical core,model physics,data assimilation,ensemble forecasting,and model evaluation strategie... This review summarizes the scientific and technical progress in atmospheric modeling in China since 2011,including the dynamical core,model physics,data assimilation,ensemble forecasting,and model evaluation strategies.In terms of the dynamical core,important efforts have been made in the improvement of the existing model formulations and in exploring new modeling approaches that can better adapt to massively parallel computers and global multiscale modeling.With regard to model physics,various achievements in physical representations have been made,especially a trend toward scale-aware parameterization for accommodating the increase of model resolution.In the field of data assimilation,a 4D-Var system has been developed and is operationally used by the National Meteorological Center of China,and its performance is promising.Furthermore,ensemble forecasting has played a more important role in operational forecast systems and progressed in many fundamental techniques.Model evaluation strategies,including key performance metrics and standardized experimental protocols,have been proposed and widely applied to better understand the strengths and weaknesses of the systems,offering key routes for model improvement.The paper concludes with a concise summary of the status quo and a brief outlook in terms of future development. 展开更多
关键词 NUMERICAL MODELING ATMOSPHERIC MODELING WEATHER and CLIMATE MODELING
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Efficient multi-response adaptive sampling algorithm for construction of variable-fidelity aerodynamic tables
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作者 Maxim TYAN Jae-Woo LEE 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第3期547-558,共12页
Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-res... Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-response adaptive sampling algorithm for simultaneous construction of multiple surrogate models in a time-efficient and accurate manner. The new algorithm uses the Jackknife cross-validation variance and a minimum distance metric to construct a sampling criterion function. A weighted sum of the function is used to consider the characteristics of multiple surrogate models. The proposed algorithm demonstrates good performance on total 22 numerical problems in comparison with three existing adaptive sampling algorithms. The numerical problems include several two-dimensional and six-dimensional functions which are combined into singleresponse and multi-response systems. Application of the proposed algorithm for construction of aerodynamic tables for 2 D airfoil is demonstrated. Scaling-based variable-fidelity modeling is implemented to enhance the accuracy of surrogate modeling. The algorithm succeeds in constructing a system of three highly nonlinear aerodynamic response surfaces within a reasonable amount of time while preserving high accuracy of approximation. 展开更多
关键词 Adaptive sampling Aerodynamic DATABASE Multi-response system Surrogate MODELING VARIABLE FIDELITY MODELING
Insight of surface treatments for CMOS compatibility of InAs nanowi
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作者 Daya S. Dhungana Anne Hemeryck +3 位作者 Nicolo Sartori Pier-Francesco Fazzini Filadelfo Cristiano Sebastien R. Plissard 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第3期581-586,共6页
A CMOS compatible process is prese nted in order to grow self-catalyzed InAs nano wires on silic on by molecular beam epitaxy. The crucial step of this process is a new in-situ surface preparation under hydrogen (gas ... A CMOS compatible process is prese nted in order to grow self-catalyzed InAs nano wires on silic on by molecular beam epitaxy. The crucial step of this process is a new in-situ surface preparation under hydrogen (gas or plasma) during the substrate degassing combined with an in-situ arsenic ann eali ng prior to growth. Morphological and structural characterizati ons of the InAs nano wires are prese nted and growth mecha nisms are discussed in detail. The major in flue nee of surface termi nation is exposed both experime ntally and theoretically using statistics on ensemble of nanowires and density functional theory (DFT) calculations. The differences observed between Molecular Beam Epitaxy (MBE) and Metal Organic Vapor Phase Epitaxy (MOVPE) growth of I nAs nano wires can be explai ned by these differe nt surfaces termi nations. The transition between a vapor solid (VS) and a vapor liquid solid (VLS) growth mechanism is presented. Optimized growth conditions lead to very high aspect ratio nano wires (up to 50 nm in diameter and 3 micron in len gth) without passi ng the 410℃ thermal limit, which makes the whole process CMOS compatible. Overall, our results suggest a new method for surface preparation and a possible tuning of the growth mechanism using different surface termi nations. 展开更多
关键词 Ⅲ-Ⅴ SEMICONDUCTORS on silicon INAS NANOWIRES self-catalyzed GROWTH hydrogen preparation GROWTH MODELING density functional theory (DFT) MODELING
新工科背景下“数字电路与Verilog设计”教学改革 预览
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作者 蔡苗 蔡红娟 周斌 《科教导刊》 2019年第20期126-127,共2页
基于技术发展、课程建设、能力培养的需要,以夯实理论基础、强化学生的现代电子技术应用能力为目标,将传统数电课程与EDA课程进行整合,从课程整合原则、课程设置目的、Verilog教学内容设计、教学安排、教学方法等方面深入阐述了'数... 基于技术发展、课程建设、能力培养的需要,以夯实理论基础、强化学生的现代电子技术应用能力为目标,将传统数电课程与EDA课程进行整合,从课程整合原则、课程设置目的、Verilog教学内容设计、教学安排、教学方法等方面深入阐述了'数字电路与Verilog设计'课程改革方案。经两轮试点验证,获得了良好的教学效果,具备一定的科学性和较强的推广性。 展开更多
关键词 数字电路 硬件描述语言 建模 教学改革
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一种重型载货汽车翻转支架的设计改进与验证分析 预览
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作者 刘言言 《机械工程师》 2019年第10期132-133,共2页
通过故障分析制定设计改进方案,并通过计算机模拟分析软件和台架试验做验证。该改进已经过市场验证,有效降低了产品的市场故障索赔成本,为同类产品设计验证提供了参考。
关键词 翻转支架 建模 有限元分析
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造型之后:关于宋元景德镇湖田窑青白釉人物瓷塑造像的几点思考 预览
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作者 赵兰涛 邓和清 《陶瓷学报》 CAS 北大核心 2019年第1期114-119,共6页
景德镇湖田窑创烧于五代,历经宋、元,结束于明代万历时期,有近700多年烧造历史,是研究景德镇制瓷工艺历史发展与变迁的一个绝佳窑厂。其中宋元时期湖田窑青白釉人物瓷塑内涵丰富,有其自身特有造型体系和审美魅力,本文依据湖田窑窑址考... 景德镇湖田窑创烧于五代,历经宋、元,结束于明代万历时期,有近700多年烧造历史,是研究景德镇制瓷工艺历史发展与变迁的一个绝佳窑厂。其中宋元时期湖田窑青白釉人物瓷塑内涵丰富,有其自身特有造型体系和审美魅力,本文依据湖田窑窑址考古出土的文物和有明确纪年的墓葬出土瓷塑,从原料、工艺技术、艺术内涵等方面来探究宋元湖田窑青白釉人物瓷塑的造型特征。 展开更多
关键词 湖田窑 青白瓷塑 造型
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以RSEI模型为基础的环境质量评价 预览
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作者 孔海燕 赵颖 +2 位作者 陈珂 张兰真 邢昱 《环境研究与监测》 2019年第1期52-55,共4页
自然生态环境是人类赖以生存和社会持续发展重要的基础条件,人类在生活和生产活动中从自然生态环境中索取重要的物质来源,同时也向自然生态环境排放各种污染物质,给自然生态环境带来了破坏。随着近年来科技进步,卫星遥感技术日新月异,... 自然生态环境是人类赖以生存和社会持续发展重要的基础条件,人类在生活和生产活动中从自然生态环境中索取重要的物质来源,同时也向自然生态环境排放各种污染物质,给自然生态环境带来了破坏。随着近年来科技进步,卫星遥感技术日新月异,给环境监测提供了很大帮助。遥感技术具有快速和实时的优势,能获取很大范围内的地表自然生态环境信息,因此在自然生态环境日常监测工作中被广泛应用,是一种科学评估自然生态环境行之有效的现代化技术手段。 展开更多
关键词 RSEI模型 环境质量评价 指标获取 建模 分析
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Improvement of groundwater resources potential by artificial recharge technique:A case study of Charf El Akab aquifer in the Tangier region,Morocco 预览
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作者 SADIKI Moulay Lhassan EL MANSOURI Bouabid +3 位作者 BENSEDDIK Badr CHAO Jamal KILI Malika EL MEZOUARY Lhoussaine 《地下水科学与工程:英文版》 2019年第3期224-236,共13页
In arid and semi-arid zones,water is the most vulnerable resource to climate change.In fact,various techniques such as artificial recharge are adopted to restore aquifers and to ensure aquifer sustainability in relati... In arid and semi-arid zones,water is the most vulnerable resource to climate change.In fact,various techniques such as artificial recharge are adopted to restore aquifers and to ensure aquifer sustainability in relation to the accelerated pace of exploitation.Morocco is a Mediterranean country highly vulnerable to climate change,many of its main aquifers are subjected to excessive drawdowns.This technique is practiced to increase potentiality of these aquifers.In the Northwestern area of Morocco,the significant development experienced by Tangier City in the industrial,tourism,and commercial sectors will lead to increased water requirements-up to 5 067 L/s(159.8 mm^3)by 2030.However,the Charf El Akab aquifer system,subject to artificial recharge,is the only groundwater resource of Tangier region;hence,a rational management context is needed to ensure aquifer sustainability,and optimized exploitation under the background of differing constraints,such as increased water requirements,and climate change impacts.This work aims to respond,for the first time,to the Charf El Akab aquifer overexploitation problem,and to evaluate the future scenarios of its exploitation in the event of failure of one of the superficial resources.This work also presents a synthesized hydrodynamic modeling based on the results of the numerical simulations carried out using Feflow software for 2004(date of cessation of injections)and 2011(date of resumption of these facilities),making it possible to evaluate the impact of the artificial recharge on the piezometric level of the aquifer on a spatiotemporal scale.Finally,the exploitation scenarios have shown that the aquifer of Charf El Akab will not adequatly provide for the region's water requirements on the future horizon,entailing an optimal management of water resources in the region and an intentionally increased recharge rate. 展开更多
关键词 Artificial RECHARGE CLIMATE change Numerical modeling Chaf EL Akab FEFLOW EXPLOITATION scenarios
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汽车发动机水泵通用化设计优势与方法 预览
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作者 张烑 赵立宏 《内燃机与配件》 2019年第5期1-2,共2页
汽车水泵是汽车动力系统发动机的重要冷却系统,发动机温度过高会使机油润滑能力下降,导致机件磨损加剧,温度高到一定值会导致发动机拉缸或烧瓦等严重故障出现,最终导致发动机烧毁报废,可见对其进行研究让其即达到使用标准又提高生产效... 汽车水泵是汽车动力系统发动机的重要冷却系统,发动机温度过高会使机油润滑能力下降,导致机件磨损加剧,温度高到一定值会导致发动机拉缸或烧瓦等严重故障出现,最终导致发动机烧毁报废,可见对其进行研究让其即达到使用标准又提高生产效率是非常具有社会价值的,本文介绍了水泵通用化设计的优势,简述了一种汽车发动机水泵通用化设计的方式、方法与思路,即通过只改变叶轮与蜗壳实现水泵通用化,利用Excel表格建立计算程序,Creo软件建立绘图模型,并对其进行了CFD模拟数据分析以验证设计的可靠性完成水泵的通用化设计。 展开更多
关键词 通用化设计 EXCEL表格 建模 性能 分析
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极限载荷分析法的有限元模型比较 预览
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作者 张福君 齐赞 《锅炉制造》 2019年第2期56-58,共3页
本文对某圆筒开孔接管结构的三种有限元模型进行了极限载荷分析,在相同载荷和约束的条件下计算了三种模型的极限载荷值,结果表明:忽略焊角高度的有限元模型与精确模型的极限载荷值比较吻合,壳单元与实体单元的计算结果非常接近,在采用... 本文对某圆筒开孔接管结构的三种有限元模型进行了极限载荷分析,在相同载荷和约束的条件下计算了三种模型的极限载荷值,结果表明:忽略焊角高度的有限元模型与精确模型的极限载荷值比较吻合,壳单元与实体单元的计算结果非常接近,在采用极限载荷法进行压力防塑性垮塌破分析时,可以采用壳单元进行计算,以节省机时。 展开更多
关键词 极限载荷分析 有限元 建模 壳单元
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智慧课堂的数据流动机制与生态系统构建
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作者 晋欣泉 邢蓓蓓 +1 位作者 杨现民 狄璇 《中国远程教育》 CSSCI 北大核心 2019年第4期74-81,91,93共10页
数据是生成课堂智慧的基础,掌握智慧课堂的数据流动是充分发挥数据教学价值的重要前提。文章通过对智慧课堂研究现状梳理分析总结存在的问题,并基于智慧课堂教学模式从课前、课中与课后三方面阐述了智慧课堂数据流动机制。在此基础上,... 数据是生成课堂智慧的基础,掌握智慧课堂的数据流动是充分发挥数据教学价值的重要前提。文章通过对智慧课堂研究现状梳理分析总结存在的问题,并基于智慧课堂教学模式从课前、课中与课后三方面阐述了智慧课堂数据流动机制。在此基础上,以信息生态学理论为指导,构建了由教学主体、教学资源、课堂环境和教学数据等要素构成的智慧课堂生态系统,包含核心层、交互层、基础层和汇聚层,指出该系统具备的三大核心特征:数据流转,实现贯通性课堂设计;数据增值,激发师生创造活力;数据决策,追求教学效益最大化。文章最后提出四条智慧课堂生态系统的构建策略:强化课堂即时反馈,实现教学数据的闭环运行;培养师生数据素养,促进课堂数据效能的发挥;强化智能感知分析,实现教学环境的智能运行;丰富智慧环境给养,满足师生多样化教学需求,为打造高效能的智慧课堂提供新思路。 展开更多
关键词 教育大数据 智慧课堂 课堂数据 数据流动 课堂生态 生态系统 构成要素 模型构建
Asymptotic analysis of a mat hematical model of the atherosclerosis development
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作者 Taras Mel'nyk 《生物数学学报:英文版》 2019年第2期49-75,共27页
A mathematical model,which takes into account new experimental results about diverse roles of macrophages in the atherosclerosis development,is proposed.Using technic of upper and lower solutions,the existence and uni... A mathematical model,which takes into account new experimental results about diverse roles of macrophages in the atherosclerosis development,is proposed.Using technic of upper and lower solutions,the existence and uniqueness of its positive solution are justified.After the nondimensionalization,small parameters are found and the multiscale analysis of the corresponding perturbed problem is performed when those parameters tend to zero.In particular,the limit two-dimensional problem,which is a coupled system of reaction-diffusion equations and ordinary differential equations,is derived;the asymptotic approximation is constructed;the uniform pointwise estimate for the difference between the solution of the original problem and the solution of the limit problem as well as the respective L^2-estimates for the fluxes are proved. 展开更多
关键词 Modeling of ATHEROSCLEROSIS ASYMPTOTIC APPROXIMATION reaction DIFFUSION system
福自何处来?--作品"福星如意壶"的创作解构 预览
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作者 鲍雯君 《中国陶瓷工业》 CAS 2019年第2期60-62,共3页
紫砂文化在历史上曾有过两次较为兴盛的时期,一次是明清时代;一次则是近代对外贸易时期。当代紫砂沐浴改革开放的春风,又一次迎来了发展的高峰。这一次推动紫砂前进的是一种全新的动力,是来自于代表传统文化的旧有紫砂与代表未来新一代... 紫砂文化在历史上曾有过两次较为兴盛的时期,一次是明清时代;一次则是近代对外贸易时期。当代紫砂沐浴改革开放的春风,又一次迎来了发展的高峰。这一次推动紫砂前进的是一种全新的动力,是来自于代表传统文化的旧有紫砂与代表未来新一代紫砂的设计创作的交融形成的动力。作品"福星如意壶"便是从中国传统的"福"文化出发,基于当代新设计思维的一次尝试。 展开更多
关键词 紫砂 福文化 设计 造型
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Ocean ecosystem discrete time dynamics generated by l-Vol terra operators
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作者 U.A.Rozikov S.K.Shoyimardonov 《生物数学学报:英文版》 2019年第2期77-100,共24页
We consider a discrete-time dynamical system generated by a nonlinear operator(with four real parameters a,b,c,d)of ocean ecosystem.We find conditions on the parameters under which the operator is reduced to a l-Volte... We consider a discrete-time dynamical system generated by a nonlinear operator(with four real parameters a,b,c,d)of ocean ecosystem.We find conditions on the parameters under which the operator is reduced to a l-Volterra quadratic stochastic operator mapping two-dimensional simplex to itself.We show that if cd(c+d)=0,then(under some conditions on a,b)this l-Volterra operator may have up to three or a countable set of fixed points;if cd(c+d)≠0,then the operator has up to three fixed points.Depending on the parameters,the fixed points may be attracting,repelling or saddle points.The limit behaviors of trajectories of the dynamical system are studied.It is shown that independently on values of parameters and on initial(starting)point,all trajectories converge.Thus,the operator(dynamical system)is regular.We give some biological interpretations of our results. 展开更多
关键词 QUADRATIC stochastic OPERATOR VOLTERRA OPERATOR l-Volterra OPERATOR ECOSYSTEM modeling
国际社交媒体谣言治理的议题与研究动向
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作者 刘丽颖 陆小聪 《传媒观察》 2019年第2期98-104,共7页
文章以2008年以来十年间EBSCO数据库收录的243篇文献作为研究对象,通过数量、国家、主题分布的比较以及主题内容的归类分析,探究国际社交媒体谣言治理的研究动向。分析表明社交媒体谣言治理已经成为发达国家的重要研究课题,运用自动化... 文章以2008年以来十年间EBSCO数据库收录的243篇文献作为研究对象,通过数量、国家、主题分布的比较以及主题内容的归类分析,探究国际社交媒体谣言治理的研究动向。分析表明社交媒体谣言治理已经成为发达国家的重要研究课题,运用自动化手段探索谣言分类、识别和过滤技术,研究谣言传播与扩散机制,以及谣言研究在社会危机事件传播、政治危机传播、公共卫生危机等方面的应用是国际学界关注的主要领域。 展开更多
关键词 国际社交媒体 谣言治理 模型建构 国际研究动态
基于UG建模的侧抽芯方法 预览
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作者 任艳霞 靳峰峰 +2 位作者 李秀副 赵会娟 孙海燕 《现代职业教育》 2019年第13期228-229,共2页
以一个需侧向抽芯的产品为载体,介绍以Mold Wizard为基础分模方法,产生主型芯、芯腔,利用建模环境中的拉伸等基础建模特征分离侧抽芯的方法。对初学者来说,该分模方法简单易懂,易操作,有利于提高模具的设计精度。
关键词 分模 侧抽芯 建模
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高空悬挑模板支撑架施工技术 预览
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作者 江宇冠 王国晖 黄春霞 《江苏建材》 2019年第A01期97-98,105共3页
分析了某工程高空悬挑模板支撑架施工过程中遇到的问题和解决办法,同时运用BIM三维技术进行施工模拟,顺利完成了高空悬挑模板支撑架体施工。
关键词 悬挑模板支撑架 高大模板 建模 连墙件
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Data-Driven Microstructure and Microhardness Design in Additive Manufacturing Using a Self-Organizing Map 预览
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作者 Zhengtao Gan Hengyang Li +5 位作者 Sarah JWolff Jennifer L.Bennett Gregory Hyatt Gregory J.Wagner Jian Cao Wing Kam Liu 《工程(英文)》 2019年第4期730-735,共6页
To design microstructure and microhardness in the additive manufacturing(AM)of nickel(Ni)-based superalloys,the present work develops a novel data-driven approach that combines physics-based models,experimental measur... To design microstructure and microhardness in the additive manufacturing(AM)of nickel(Ni)-based superalloys,the present work develops a novel data-driven approach that combines physics-based models,experimental measurements,and a data-mining method.The simulation is based on a computational thermal-fluid dynamics(CtFD)model,which can obtain thermal behavior,solidification parameters such as cooling rate,and the dilution of solidified clad.Based on the computed thermal information,dendrite arm spacing and microhardness are estimated using well-tested mechanistic models.Experimental microstructure and microhardness are determined and compared with the simulated values for validation.To visualize process-structure-properties(PSPs)linkages,the simulation and experimental datasets are input to a data-mining model-a self-organizing map(SOM).The design windows of the process parameters under multiple objectives can be obtained from the visualized maps.The proposed approaches can be utilized in AM and other data-intensive processes.Data-driven linkages between process,structure,and properties have the potential to benefit online process monitoring control in order to derive an ideal microstructure and mechanical properties. 展开更多
关键词 Additive manufacturing Data science Multiphysics modeling Self-organizing map MICROSTRUCTURE MICROHARDNESS Ni-based superalloy
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Geometric error analysis of an over-constrained parallel tracking mechanism using the screw theory
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作者 Jiateng ZHANG Binbin LIAN Yimin SONG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第6期1541-1554,共14页
This paper deals with geometric error modeling and sensitivity analysis of an overconstrained parallel tracking mechanism. The main contribution is the consideration of overconstrained features that are usually ignore... This paper deals with geometric error modeling and sensitivity analysis of an overconstrained parallel tracking mechanism. The main contribution is the consideration of overconstrained features that are usually ignored in previous research. The reciprocal property between a motion and a force is applied to tackle this problem in the framework of the screw theory. First of all, a nominal kinematic model of the parallel tracking mechanism is formulated. On this basis, the actual twist of the moving platform is computed through the superposition of the joint twist and geometric errors. The actuation and constrained wrenches of each limb are applied to exclude the joint displacement. After eliminating repeated errors brought by the multiplication of wrenches, a geometric error model of the parallel tracking mechanism is built. Furthermore,two sensitivity indices are defined to select essential geometric errors for future kinematic calibration. Finally, the geometric error model with minimum geometric errors is verified by simulation with SolidWorks software. Two typical poses of the parallel tracking mechanism are selected, and the differences between simulation and calculation results are very small. The results confirm the correctness and accuracy of the geometric error modeling method for over-constrained parallel mechanisms. 展开更多
关键词 ERROR model simulation GEOMETRIC ERROR modeling Over-constrained PARALLEL MECHANISM Screw theory Sensitivity analysis
轮式装载机工作装置液压系统的仿真分析
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作者 罗剑 《国外电子测量技术》 2019年第5期62-64,共3页
为了给装载机液压系统的节能优化改进提供理论支撑,以ZL30B型轮式装载机工作装置的液压系统为研究对象,完成了对系统的建模仿真分析。首先介绍了系统工作原理,然后利用AMEsim软件中的标准液压库元件完成对安全阀、多路阀动臂液压缸、转... 为了给装载机液压系统的节能优化改进提供理论支撑,以ZL30B型轮式装载机工作装置的液压系统为研究对象,完成了对系统的建模仿真分析。首先介绍了系统工作原理,然后利用AMEsim软件中的标准液压库元件完成对安全阀、多路阀动臂液压缸、转斗液压缸以及定量泵的建模,采用Planar Mechanical库元件实现对反转六杆式工作机构的建模,同时明确了工作装置各液压缸的相对位置。最后在此基础上进行了仿真,通过仿真数据与实测数据的比对,证明了构建的工作装置液压系统模型能够准确反映系统的性能。除此之外,忽略管路沿程压力损失及多路阀的节流作用的情况下,系统的实测效率为16.3%,而通过计算获得的工作效率为12.2%,所以认定构建的模型可以较好地表征系统的工作效率。从而最终验证了工作装置液压系统仿真模型的准确性。 展开更多
关键词 轮式装载机 AMESIM 建模 工作装置 仿真
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