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Step-by-Step Numerical Prediction of Aerodynamic Noise Generated by High Speed Trains

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Chinese Journal of Mechanical Engineering 2022年第2期35卷 251-264页

作者： Tian Li Deng Qin Ning Zhou weihua zhang State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China

In this paper,the unsteady flow around a high-speed train is numerically simulated by detached eddy simulation method(DES),and the far-field noise is predicted using the Ffowcs Williams-Hawkings(FW-H)acoustic *** reliability of the numerical calculation is verified by wind tunnel *** superposition relationship between the far-field radiated noise of the local aerodynamic noise sources of the high-speed train and the whole noise source is *** the aerodynamic noise of high-speed trains is derived from its different components,a stepwise calculation method is proposed to predict the aerodynamic noise of high-speed *** results show that the local noise sources of high-speed trains and the whole noise source conform to the principle of sound source energy *** the head,middle and tail cars of the high-speed train as noise sources,different numerical models are established to obtain the far-field radiated noise of each aerodynamic noise *** far-field total noise of high-speed trains is predicted using sound source superposition.A step-by-step calculation of each local aerodynamic noise source is used to obtain the superimposed value of the far-field *** is consistent with the far-field noise of the whole train model’s aerodynamic *** averaged sound pressure level of the far-field longitudinal noise measurement points differs by 1.92 *** step-by-step numerical prediction method of aerodynamic noise of high-speed trains can provide a reference for the numerical prediction of aerodynamic noise generated by long marshalling high-speed trains.

关键词： High-speed train Aerodynamic noise Sound source superposition Numerical prediction

预训练模型驱动的固体火箭发动机总体优化设计

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推进技术 2024年第7期45卷 16-24页

作者：高经纬马帅超彭博武泽平张为华国防科技大学空天科学学院湖南长沙410073

优化设计是固体火箭发动机设计的重要手段。针对现有固体火箭发动机优化设计方法模型调用次数多、优化效率低的问题,提出预训练模型驱动的固体火箭发动机优化设计方法。基于已有设计案例,提出固体火箭发动机几何-性能参数映射方法,将已... 详细信息

优化设计是固体火箭发动机设计的重要手段。针对现有固体火箭发动机优化设计方法模型调用次数多、优化效率低的问题,提出预训练模型驱动的固体火箭发动机优化设计方法。基于已有设计案例,提出固体火箭发动机几何-性能参数映射方法,将已有仿真结果转化为目标需求下的训练样本,由此构建预训练模型。基于预训练模型进行初始样本点筛选和模型响应预测,结合多可信度代理模型技术,在较少仿真模型调用次数下定位问题全局最优,提升了固体火箭发动机总体优化效率。对翼柱形装药固体火箭发动机进行优化设计,结果表明,基于200个已有设计案例建立预训练模型,只需调用30次高精度仿真模型即可完成优化设计,相比于传统直接优化设计的64次模型调用可大幅减少仿真模型调用次数,提高了设计效率,验证了本方法的高效性和有效性。

关键词：固体火箭发动机优化设计代理模型多可信度模型案例映射

经内窥镜大隐静脉获取术在冠状动脉旁路移植术中应用的学习曲线

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中山大学学报（医学科学版） 2024年第2期45卷 319-323页

作者：张伟华张俭孙晓柯罗鸿马宁刘东海张新乔晨晖郑州大学第一附属医院心血管外科河南郑州450000

【目的】探讨内窥镜获取大隐静脉在冠状动脉旁路移植术中的应用并探讨学习曲线,重点关注初学者易发生的问题及对早期临床结果的影响。【方法】回顾性分析2013年7月至2014年4月在郑州大学第一附属医院心外科接受不停跳冠状动脉旁路移植... 详细信息

【目的】探讨内窥镜获取大隐静脉在冠状动脉旁路移植术中的应用并探讨学习曲线,重点关注初学者易发生的问题及对早期临床结果的影响。【方法】回顾性分析2013年7月至2014年4月在郑州大学第一附属医院心外科接受不停跳冠状动脉旁路移植术并使用内窥镜技术获取大隐静脉的83例患者的临床资料,按照手术时间的先后顺序分为A组(初学组20例)、B组(熟悉组20例)、C组(进步组20例)、D组(成熟组23例),分析各组之间患者围术期及随访结果差异,明确学习曲线周期。【结果】该组患者年龄为(60.22±8.06)岁,体质量为(69.77±11.66)kg,其中合并高血压24例、糖尿病26例、亚急性脑梗14例。A组相对于后三组获取大隐静脉长度与时间比值明显较小(P<0.001),静脉主干损伤数量明显较多(P=0.006),并且随访1年时静脉桥通畅率较低,但差异无统计学意义。【结论】内窥镜获取大隐静脉之前技术操作培训是必要的,能有效规避初学者造成的血管损伤,实际获取的过程中大概需要亲自操作20例,并认真总结技术技巧就可以较为熟练地进行相关操作。

关键词：冠状动脉旁路移植术内窥镜微创大隐静脉学习曲线

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基于深度矩阵分解的无人感知系统信号补全方法研究

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汽车工程学报 2024年第5期14卷 801-811页

作者：钟岳徐峰张纬华中国人民解放军32184部队北京100071

针对当前无人车行驶过程中存在的异常信号测试手段缺乏问题,以可靠性行驶试验中受到环境干扰等导致的信号异常为例,利用感知系统中多传感器感知信号在时域和空域上的相关性,建立多传感器采集数据信息间的交叉数学模型,提出将传感器采集... 详细信息

针对当前无人车行驶过程中存在的异常信号测试手段缺乏问题,以可靠性行驶试验中受到环境干扰等导致的信号异常为例,利用感知系统中多传感器感知信号在时域和空域上的相关性,建立多传感器采集数据信息间的交叉数学模型,提出将传感器采集信号和各传感器分别作为信号矩阵的行列元素,通过此数值化方式将原始多传感器信号转化为可参数化的信号矩阵模型。还提出了一种基于矩阵补全和深度矩阵分解融合(MC+DMF)的方法恢复由于环境干扰等导致的部分异常信号,根据神经网络前向传播特性,将原始矩阵中的行向量(单个传感器在i时刻的各采集数据)和列向量(传感器向量)进行降维,降低失真信号矩阵在特征提取过程中的计算量,利用Hadamard乘积对特征提取后的损失函数正则化避免出现过拟合,将该方法运用至SODA10M和KITTI公开数据集中,并与传统的单一矩阵分解(MF)、概率矩阵分解(PMF)、带偏置的奇异值分解(Bias-SVD)方法进行均方根误差(MAE)对比试验,可有效检测到行驶过程中出现的异常信号传感器。结果表明,深度矩阵分解方法能极大地降低数据恢复误差和时间,相较于概率矩阵分解方法,其误差率低1%,恢复时间少约20.65%。

关键词：环境干扰异常信号矩阵补全多传感器融合深度矩阵分解

Gradient-based Kriging approximate model and its application research to optimization design

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Science China(Technological Sciences) 2009年第4期52卷 1117-1124页

作者： XUAN Ying XIANG JunHua zhang weihua zhang YuLin College of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China

In the process of multidisciplinary design optimization, there exits the calculation complexity problem due to frequently calling high fidelity system analysis models. The high fidelity system analysis models can be surrogated by approximate models. The sensitivity analysis and numerical noise filtering can be done easily by coupling approximate models to optimization. Approximate models can reduce the number of executions of the problem's simulation code during optimization, so the solution efficiency of the multidisciplinary design optimization problem can be improved. Most optimization methods are based on gradient. The gradients of the objective and constrain functions are gained easily. The gra- dient-based Kriging (GBK) approximate model can be constructed by using system response value and its gradients. The gradients can greatly improve prediction precision of system response. The hybrid optimization method is constructed by coupling GBK approximate models to gradient-based optimiza- tion methods. An aircraft aerodynamics shape optimization design example indicates that the methods of this paper can achieve good feasibility and validity.

关键词： Kriging approximation function gradient-based approximate model hybrid optimization method multidisciplinary design optimization

Dynamics of high speed wheel/rail system and its modelling

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Chinese Science Bulletin 2007年第11期52卷 1566-1575页

作者： zhang ShuGuang zhang weihua JIN XueSong Transportation Bureau of Railway Ministry of China Beijing 100844 China State Key Laboratory of Traction Power Southwest Jiaotong University Chengdu 610031 China

With the fast increasing of train speed the interactions among the train,the track,and the power cate-nary system become very strong. Such interactions are also strongly coupled with the action of high speed airflow due to the high speed running. Hence,the existing research methods and numerical al-gorithms of railway vehicle/track systems are not fully available for characterizing the transient dy-namic and long-term behaviors of train/track at higher speed. The present paper reviews the existing studies on coupling dynamics of railway vehicle/track,and clarifies their advantages and disadvan-tages and then puts forward an innovation stratagem for high speed railway based on rolling contact of wheel/rail systems. In the innovation stratagem,a comprehensive dynamic model of wheels/rails sys-tems is developed to simultaneously consider the track system,the train,the rolling contact of wheel/rail,the catenary/pantograph system,and the high speed airflow with the train. The motion equations of the subsystems and their coupling boundaries are given and discussed. For the reliability and safety of the high speed train in service,the long-term behavior of the structures of the train and the track is considered in the comprehensive model. Moreover,a generalized failure model,consider-ing the structures and the materials and working in the comprehensive dynamic model of wheels/rails system,as well as the simulation system of structure failure of the high speed train/track is established. Consequently,the present studies on the dynamics of the coupled vehicle/track will be further and largely extended.

关键词：铁轨火车悬链线故障模拟车轮

Effect of RANS Model on the Aerodynamic Characteristics of a Train in Crosswinds Using DDES

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Computer Modeling in Engineering & Sciences 2020年第2期122卷 555-570页

作者： Tian Li Zhiyuan Dai weihua zhang State-Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu610031China.

Detached eddy simulation has been widely applied to simulate the flow around trains in recent *** Reynolds-averaged Navier-Stokes(RANS)model for delayed detached eddy simulation(DDES)is an essential user *** effect of the RANS model for DDES on the aerodynamic characteristics of a train in crosswinds is investigated in this *** different DDES models are used,based on the Spalart-Allmaras model(SA),the realizable k-εmodel(RKE),and the shear stress transport k-ωmodel(SST).Results show that all DDES models can give relatively accurate predictions of pressure coefficient on almost all *** are only some specific differences in the small vortices,while similar flow patterns around trains could be *** SST based DDES model(SSTDDES)gives the most accurate numerical results among the three models for the surface *** variations in pressure on the leeward face play a key role in the variation of the side force.

关键词： Numerical simulation DES train aerodynamics crosswind RANS.

Research Progress of Aerodynamic Multi-Objective Optimization on High-Speed Train Nose Shape

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Computer Modeling in Engineering & Sciences 2023年第11期137卷 1461-1489页

作者： Zhiyuan Dai Tian Li weihua zhang Jiye zhang State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu610031China

The aerodynamic optimization design of high-speed trains(HSTs)is crucial for energy conservation,environmental preservation,operational safety,and speeding *** study aims to review the current state and progress of the aerodynamic multi-objective optimization of ***,the study explores the impact of train nose shape parameters on aerodynamic *** parameterization methods involved in the aerodynamic multiobjective optimization ofHSTs are summarized and classified as shape-based and disturbance-based ***,the advantages and limitations of each parameterizationmethod,aswell as the applicable scope,are briefly *** addition,the NSGA-II algorithm,particle swarm optimization algorithm,standard genetic algorithm,and other commonly used multi-objective optimization algorithms and the improvements in the field of aerodynamic optimization for HSTs are ***,this study investigates the aerodynamic multi-objective optimization technology for HSTs using the surrogate model,focusing on the Kriging surrogate models,neural network,and support vector ***,the construction methods of surrogate models are summarized,and the influence of different sample infill criteria on the efficiency ofmulti-objective optimization is ***,advanced aerodynamic optimization methods in the field of aircraft have been briefly introduced to guide research on the aerodynamic optimization of ***,based on the summary of the research progress of the aerodynamicmulti-objective optimization ofHSTs,future research directions are proposed,such as intelligent recognition technology of characteristic parameters,collaborative optimization of multiple operating environments,and sample infill criterion of the surrogate model.

关键词： High-speed train multi-objective optimization parameterization optimization algorithm surrogate model sample infill criterion

DavidⅠ与Bentall术用于急性主动脉夹层的单中心疗效分析

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临床荟萃 2024年第5期39卷 420-425页

作者：刘洋马宁张伟华郑州大学第一附属医院心血管外科河南郑州450052

目的比较单中心DavidⅠ与Bentall手术用于急性主动脉夹层的疗效。方法选取2020年1月至2022年12月于郑州大学第一附属医院心血管外科住院治疗的急性主动脉夹层患者28例,按照手术方法分为DavidⅠ组(n=13)和Bentall(n=15),DavidⅠ组采用Da... 详细信息

目的比较单中心DavidⅠ与Bentall手术用于急性主动脉夹层的疗效。方法选取2020年1月至2022年12月于郑州大学第一附属医院心血管外科住院治疗的急性主动脉夹层患者28例,按照手术方法分为DavidⅠ组(n=13)和Bentall(n=15),DavidⅠ组采用DavidⅠ手术,Bentall组采用Bentall手术。随访1年,比较2组围术期相关指标、心脏指标、并发症。结果与Bentall组比较,DavidⅠ组手术时间、转机时间、主动脉阻断时间更长(P0.05)。2组术前和术后1年左心室射血分数、升主动脉最大内径、左心室舒张末期内径差异均无统计学意义(P>0.05);与术前比较,DavidⅠ组术后1年左心室射血分数降低(P0.05)。结论DavidⅠ与Bentall手术应用于急性主动脉夹层治疗的早期指标,术后生存率、瓣膜相关并发症等无明显差异。Bentall手术的手术时间、转机时间、主动脉阻断时间更短。

关键词：主动脉夹层 DavidⅠ手术 Bentall手术疗效

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