检索结果-南通市图书馆

Supervised learning with probability interpretation in airfoil transition judgment

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第1期36卷 91-104页

作者： Binbin WEI yongwei gao Dong LI Lei DENG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China

Transition prediction has always been a frontier issue in the field of aerodynamics.A supervised learning model with probability interpretation for transition judgment based on experimental data was developed in this paper.It solved the shortcomings of the point detection method in the experiment,that which was often only one transition point could be obtained,and comparison of multi-point data was necessary.First,the Variable-Interval Time Average(VITA)method was used to transform the fluctuating pressure signal measured on the airfoil surface into a sequence of states which was described by Markov chain model.Second,a feature vector consisting of one-step transition matrix and its stationary distribution was extracted.Then,the Hidden Markov Model(HMM)was used to pre-classify the feature vectors marked using the traditional Root Mean Square(RMS)criteria.Finally,a classification model with probability interpretation was established,and the cross-validation method was used for model validation.The research results show that the developed model is effective and reliable,and it has strong Reynolds number generalization ability.The developed model was theoretically analyzed in depth,and the effect of parameters on the model was studied in detail.Compared with the traditional RMS criterion,a reasonable transition zone can be obtained using the developed classification model.In addition,the developed model does not require comparison of multi-point data.The developed supervised learning model provides new ideas for the transition detection in flight experiments and other experiments.

关键词： Classification model Hidden Markov model Markov chain model Supervised learning Transition judgment

Variable slip window technology in transition detection on pitching airfoil

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第4期33卷 1166-1180页

作者： Binbin WEI yongwei gao Dong LI Lei DENG School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China

In the pitching motion,the unsteady transition and relaminarization position plays an important role in the dynamic characteristics of the airfoil.In order to facilitate the computer to automatically and accurately calculate the position of the transition and relaminarization,a Variable Slip Window Technology(VSWT)suitable for airfoil dynamic data processing was developed using the S809 airfoil experimental data in this paper and two calculation strategies,i.e.,global strategy and single point strategy,were proposed:global strategy and single point strategy.The core of the VSWT is the selection of the window function h and the parameters setting in the h function.The effect of the VSWT was evaluated using the dimensionless pulse strength value(INB),which can be used to evaluate the signal characteristics,of the root mean square(RMS)value of the fluctuating pressure.It is found that:the h function characteristics have a significant influence on the VSWT.The suitable functions are Hn function constructed in this paper and step function.For the left boundary of the magnified area,the step function can obtain the largest INB value,but the robustness is not good.The H1 function(Gaussian-like function,n=1)can show higher robustness while ensuring a large INB value.The two computing strategies,which are single point strategy and global strategy,have their own advantages and disadvantages.The former strategy,that is the single point strategy,can achieve a higher INB value,but the RMS magnification at the feature position needs to be known in advance.Although the INB value obtained by the latter strategy,that is the global strategy,is slightly smaller than the calculation results of the former strategy,it is not necessary to know the RMS magnification at the feature position in advance.So the global strategy has better robustness.The experimental data of NACA0012 airfoil was used to further validate the developed VSWT in this paper,and the results show that the VSWT developed in this paper can still double the INB value o

关键词： Data processing Dynamic characteristics Pitching airfoil Transition and relaminarization Variable slip window technology(VSWT)

A conceptual design for deflection device in VTDP system

在线全文

学校读者我要写书评

暂无评论

Advances in Aerodynamics 2021年第1期3卷 29-48页

作者： yongwei gao Jianming Zhang Long Wang Bingzhen Chen Binbin Wei School of Aeronautics Northwestern Polytechnical University127 West Youyi RoadBeilin DistrictXi’anShaanxi 710072People’s Republic of China

The effectiveness of the Vectored Thrust Ducted Propeller(VTDP)system is not high currently,especially the lateral force is not large enough.Thus,a conceptual design for a deflection device of a VTDP system was proposed to achieve effective hovering control.The magnitude of the lateral force that was applied to maintain balance while hovering was examined.A comparison between the experimental and numerical results for the 16H-1 was made to verify the numerical simulation approach.The deflection devices of the X-49 and the proposed design were analyzed using numerical simulations.The results indicated that a larger lateral force and lower power consumption were presented in the proposed design.The results of this article provide a new idea for the design of the VTDP system.

关键词： Vectored thrust ducted propeller Conceptual design Wind tunnel experiment Numerical simulation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

从冬奥会术语谈英汉词典的修订

辞书研究 2024年第1期 76-86,I0002页

作者：黄锦鸿高永伟复旦大学外文学院上海200433

《英汉大词典》《新世纪英汉大词典》应适当收录《冬奥会体育项目名词》中的一些常用术语。文章探讨了上述两部词典和《冬奥会体育项目名词》在冬奥会术语收录和翻译上存在的问题,结合若干实例,从术语及其译名的动态性与系统性、术语译... 详细信息

《英汉大词典》《新世纪英汉大词典》应适当收录《冬奥会体育项目名词》中的一些常用术语。文章探讨了上述两部词典和《冬奥会体育项目名词》在冬奥会术语收录和翻译上存在的问题,结合若干实例,从术语及其译名的动态性与系统性、术语译名的确切性、译名的规范化与常用性、术语在不同学科或分支学科之间的定名四个方面提出英汉词典和术语手册在冬奥会术语改进上的建议,以期对它们在今后的修订中进一步提高其整体质量和实用价值有所裨益。

关键词：冬奥会术语英汉词典术语收录译名词典修订

在线全文

学校读者我要写书评

暂无评论

多体分离中初始扰动发展模式的理论分析

航空学报 2024年第12期45卷 82-94页

作者：魏斌斌高永卫孙博张亚龙胡淑玲郝礼书西安交通大学航天航空学院西安710049 西北工业大学航空学院西安710072

以载机-无人机分离系统为研究对象,基于六自由度运动方程,首次建立了初始扰动发展理论分析模型,得到了扰动幅值发展的显式表达,并首次给出了扰动分布的发展模式。研究表明:在对建立的理论分析模型进行求解时,对加速度/角加速度在初始时... 详细信息

以载机-无人机分离系统为研究对象,基于六自由度运动方程,首次建立了初始扰动发展理论分析模型,得到了扰动幅值发展的显式表达,并首次给出了扰动分布的发展模式。研究表明:在对建立的理论分析模型进行求解时,对加速度/角加速度在初始时刻进行三阶Taylor展开即可对扰动发展模式进行准确描述。扰动幅值在速度扰动方向上以线性增长模式为主导,增长率为速度初始扰动的标准差;扰动幅值在其他方向上呈非线性增长模式。扰动施加方向上的分布发展基本模式是初始分布;在其他方向上,加速度/角加速度在初始时刻的Taylor展开零阶项与初始分布一致,但高阶项显著偏离初始分布,随着时间的推进,高阶项逐渐主导整体的扰动分布,并致其逐渐偏离初始分布。

关键词：多体分离初始扰动扰动发展理论蒙特卡罗打靶无人机

基于误差反向传播神经网络的机弹分离轨迹预测研究

在线全文

学校读者我要写书评

暂无评论

气动研究与试验

气动研究与试验 2024年第2期2卷 59-65页

作者：胡豹高永卫昔华倩西北工业大学航空学院陕西西安710072

载机投放炸弹或发射导弹的机弹分离过程对于飞行安全和任务完成具有重要意义。为了从有限的试验或计算数据中尽可能全面、细致地预测分离轨迹,根据某型飞机投弹的计算流体力学模拟结果,基于误差反向传播(BP)神经网络方法,研究确定了模... 详细信息

载机投放炸弹或发射导弹的机弹分离过程对于飞行安全和任务完成具有重要意义。为了从有限的试验或计算数据中尽可能全面、细致地预测分离轨迹,根据某型飞机投弹的计算流体力学模拟结果,基于误差反向传播(BP)神经网络方法,研究确定了模型的隐藏层层数、隐藏层神经元数目和训练函数,建立了分离过程中导弹的空气动力学性能预测模型。经与风洞试验结果对比验证,本文基于BP神经网络的机弹分离轨迹预测方法可行,为类似问题的研究提供参考思路。

关键词：轨迹预测机弹分离预测模型 BP神经网络安全边界

Aerosol transportation in horizontal channels w让h gravitational effects

在线全文

学校读者我要写书评

暂无评论

Particuology 2019年第3期17卷 159-168页

作者： yongwei gao Ke Zhong Yanming Kang School of Environmental Science and Engineering Donghua University Shanghai 201620 China School of Physics and Electronic-Electrical Engineering Ningxia University Yinchuan 750021 China

Aerosol particle deposition in a narrow horizontal channel with gravitational effects is studied in the laminar flow regime. A general explic让 solution for predicting the aerosol transportation in the channel is obtained theoretically. The characteristics of the asymmetric concentratio n profiles and their dependence on gravitational settling are analyzed for different settings of the diffusion and sedimentation parameters. Aerosol deposition on the channel walls, which is influenced by a combination of mechanisms, is also analyzed. The results are compared with those from simplified models obtained in previous studies in which only diffusion or gravity was considered. The analysis reveals that the literature results regarding this aspect may be simplified with the present solution under specific conditions.

关键词： Exact solution Combined deposition Gravitational effect Horizontal channel Asymmetric distribution

迟发性鸟氨酸氨甲酰转移酶缺乏症1例的OTC基因变异分析

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国计划生育学杂志 2024年第2期32卷 379-381页

作者：祖丽胡玛尔·日夏提罗燕飞孙光辉高永伟米热古丽·买买提新疆医科大学第一附属医院乌鲁木齐830054

目的:对1例迟发型鸟氨酸氨甲酰转移酶缺乏症(OTCD)患儿的临床特点及OTC基因变异进行分析,提高对鸟氨酸氨甲酰转移酶缺乏症的认识。方法:对2023年2月20日本院收治的1例OTCD患儿及父母外周血样,采用高通量测序的方法进行全外显子测序(WES)... 详细信息

目的:对1例迟发型鸟氨酸氨甲酰转移酶缺乏症(OTCD)患儿的临床特点及OTC基因变异进行分析,提高对鸟氨酸氨甲酰转移酶缺乏症的认识。方法:对2023年2月20日本院收治的1例OTCD患儿及父母外周血样,采用高通量测序的方法进行全外显子测序(WES),对候选致病变异进行Sanger测序验证及生物信息学分析变异蛋白结构。结果:患儿OTC基因第4外显子存在c.356G>A(p.Gly119Asp)变异。根据美国医学遗传学与基因组学学会变异相关指南,判定为可能致病性变异(PM1+PM2_Supporting+PP3_Strong),在多个正常人群数据库的频率为0,采用Sanger测序技术对先证者及其父母OTC基因变异验证。先证者的变异经一代测序技术证实,生母携带此杂合变异。结论:OTC基因变异可能是此例迟发型OTCD患儿的遗传学病因。c.356G>A的发现丰富了OTC基因的变异谱。提示基因检测在代谢疾病中的重要性。

关键词：鸟氨酸氨甲酰转移酶缺乏症 OTC基因血尿有机酸分析全外显子组测序

在线全文

学校读者我要写书评

暂无评论

赫美玲《英汉官话词典和翻译手册》谱系研究

国际汉学 2022年第2期 153-162,206页

作者：高永伟复旦大学外文学院

来华人士所编的双语词典在我国早期双语词典编纂史上产生了巨大的影响。赫美玲在1916年所编的《英汉官话词典和翻译手册》,在词典史上起到了承前启后的作用。本文从词典学的角度出发,以词典谱系学为基础,论述赫美玲词典从蓝本到修订版... 详细信息

来华人士所编的双语词典在我国早期双语词典编纂史上产生了巨大的影响。赫美玲在1916年所编的《英汉官话词典和翻译手册》,在词典史上起到了承前启后的作用。本文从词典学的角度出发,以词典谱系学为基础,论述赫美玲词典从蓝本到修订版的演变,剖析该词典在收词和翻译方面的特点和不足,总结其作用与影响。

关键词：赫美玲《英汉官话词典和翻译手册》双语词典词典谱系