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Prescribed fast tracking control for flexible air-breathing hypersonic vehicles:An event-triggered case

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Chinese Journal of Aeronautics 2021年第11期34卷 200-215页

作者： Xingling SHAO Yi SHI Wendong ZHANG jiang zhao The Key Laboratory of Instrumentation Science&Dynamic Measurement Ministry of EducationNorth University of ChinaTaiyuan 030051China School of Instrument and Electronics North University of ChinaTaiyuan 030051China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

In this paper,a prescribed fast tracking control scheme is proposed for Flexible Airbreathing Hypersonic Vehicles(FAHV)subject to lumped disturbances and limited *** maintain tracking errors of velocity and altitude converge to a predefined region with a prescribed time and release the transient intense fluctuations encountered in classical Prescribed Performance Control(PPC)using a fast decaying rate,a tracking differentiator-based PPC is presented,where the reaching time and the maximum time differentiation of preselected envelopes can be regulated as a prior via fixing an acceleration factor,so that a guaranteed fast convergence speed can be realized with reduced ***,to avoid the excessive occupation of limited resources(energy and communication)and guarantee a remarkable tracking accuracy,switching event-triggered mechanisms are constructed for FAHV control realization,which provide a promising way to pursue a desired level of tracking performance with a low energy ***,Uncertainty and Disturbance Estimators(UDE)and Sigmoid function-based Tracking Differentiators(STD)are employed to provide disturbance estimation and reference derivation with a low computational ***,robust control laws are designed to compensate for the sampling error induced by event-triggered conditions,meanwhile Zeno phenomena can be effectively *** simulation results and comparisons validate the effectiveness of the proposed scheme.

关键词： Flexible air-breathing hypersonic vehicle Prescribed performance control Switching event-triggered Tracking differentiator Uncertainty and disturbance estimator

Predictor-based model reference adaptive roll and yaw control of a quad-tiltrotor UAV

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Chinese Journal of Aeronautics 2020年第1期33卷 282-295页

作者： Ningjun LIU Zhihao CAI jiang zhao Yingxun WANG School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100083China

An attempt is made to apply modern control technology to the roll and yaw control of a rudderless quad-tiltrotor Unmanned Aerial Vehicle(UAV)in the latter part of the flight mode transition,where aerodynamic forces on the tiltrotor’s wings start to take effect.A predictor-based adaptive roll and yaw controller is designed to compensate for system uncertainties and parameter changes.A dynamics model of the tiltrotor is built.A Radial-Basis Function(RBF)neural network and offline adaptation method are used to reduce flight controller workload and cope with the nonlinearities in the *** are conducted to verify the reference model response tracking and yaw-roll control decoupling ability of the adaptive controller,as well as the validity of the offline adaptation *** tests are conducted to confirm the ability of the adaptive controller to track different roll and yaw reference model *** decoupling of roll and yaw controls is also tested in flight via coordinated turn maneuvers with different rotor tilt angles.

关键词： Adaptive control Flight control Tiltrotor UAV VTOL

Fast level-flight to hover mode transition and altitude control in tiltrotor’s landing operation

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Chinese Journal of Aeronautics 2021年第1期34卷 181-193页

作者： Ningjun LIU Zhihao CAI Yingxun WANG jiang zhao Institute of Unmanned System Beihang UniversityBeijing 100083China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100083China

An attempt is made to implement a faster level-flight to hover mode transition in tiltrotor’s landing process for the purpose of shortening its landing time. A three-stage tiltrotor landing maneuver is designed, and corresponding control modules and algorithms are created based on the analysis of the flight dynamics and the required actions of tiltrotor’s landing operation. As the altitude control is vital for tiltrotor’s near-ground landing, an Extended State Observer(ESO) control module of the Active Disturbance Rejection Control(ADRC) is designed to reduce altitude fluctuations in the fast mode transition, which makes the designed maneuver workable at very low altitudes. Simulations are conducted to verify the effectiveness of the designed maneuver and the validity of ESO control in various flight conditions. Flight test results that finally prove the effectiveness of the desired fast transition maneuver are reported.

关键词： Tiltrotor Transition Flight control VTOL UAV ADRC

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基于交叉注意力机制的多模态感知融合方法

中国公路学报 2024年第3期37卷 181-193页

作者：张炳力潘泽昊姜俊昭张成标王怿昕杨程磊合肥工业大学汽车与交通工程学院安徽合肥230041 安徽省智能汽车工程实验室安徽合肥230009

针对智能汽车道路目标检测任务中单一传感器感知能力有限、多传感器后融合处理复杂等问题,提出了一种基于Transformer交叉注意力机制的多模态感知融合方法。首先,利用交叉注意力机制能较好地融合多模态信息的优势,搭建了基于深度学习方... 详细信息

针对智能汽车道路目标检测任务中单一传感器感知能力有限、多传感器后融合处理复杂等问题,提出了一种基于Transformer交叉注意力机制的多模态感知融合方法。首先,利用交叉注意力机制能较好地融合多模态信息的优势,搭建了基于深度学习方式的端到端融合感知网络,用以接收视觉与点云检测网络的输出,并进行后融合处理。其次,对点云检测网络的三维目标信息进行高召回处理,与视觉图像检测器输出的道路目标信息一同作为网络的输入。最后,通过网络实现二维目标信息向三维信息的融合,输出对三维目标检测信息的修正,从而得到准确度更高的后融合检测信息。在KITTI公开数据集上的验证指标表明,通过所提融合方法引入二维检测信息后,相比较PointPillars、PointRCNN、PV-RCNN及CenterPoint四种基准方法,对车辆、骑行人、行人3种类别的综合平均提升分别为7.07%、2.82%、2.46%、1.60%。通过与基于规则的后融合方法对比,所提融合网络在行人和骑行人中等、困难样本检测上,分别有平均1.88%与4.90%的提升。进一步表明所提方法具有更强的适应性与泛化能力。最后,进行了实车试验平台的搭建及算法验证,选取实车试验场景进行可视化定性分析,在实际道路场景下验证了所提检测方法与网络模型。

关键词：汽车工程多模态融合交叉注意力机制三维目标检测后融合信息修正

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连云港市小学生科学素养现状调查与分析

连云港师范高等专科学校学报 2024年第2期41卷 100-104页

作者：王英周艳玮赵江连云港师范高等专科学校初等教育学院江苏连云港222006 连云港师范高等专科学校海洋港口学院江苏连云港222006

本研究以连云港市区、县镇和农村小学5-6年级的小学生为调查对象,基于4个科学素养模块编制问卷,对他们进行科学素养调查。调查结果显示,调查对象对科学精神内涵了解不深,崇尚科学、辨别信息真伪的能力不强,这表明小学科学课程的教学需... 详细信息

本研究以连云港市区、县镇和农村小学5-6年级的小学生为调查对象,基于4个科学素养模块编制问卷,对他们进行科学素养调查。调查结果显示,调查对象对科学精神内涵了解不深,崇尚科学、辨别信息真伪的能力不强,这表明小学科学课程的教学需要得到重视和改进。研究在评估连云港市小学生科学素养现状的基础上提出相关建议,为改进相关工作提供参考。

关键词：小学生科学素养连云港市调查

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大规格气阀电镦成形参数加载模式设计及应用

锻压技术 2024年第7期49卷 160-167页

作者：权国政余炎泽赵江许东晓戴魏魏重庆大学材料科学与工程学院重庆400044 南京中远海运船舶设备配件有限公司、江苏省船舶动力系统零件先进制造工程技术研究中心江苏南京211121

大规格气阀电镦过程是一个超长程、超长时塑性变形过程,如何通过设计电镦加载路径以实现变形和晶粒尺寸的协调控制是一个困难且重要的问题。针对此问题,基于电-热-力多场耦合分析理论和晶粒尺寸演变模型,建立了大规格气阀电镦成形过程... 详细信息

大规格气阀电镦过程是一个超长程、超长时塑性变形过程,如何通过设计电镦加载路径以实现变形和晶粒尺寸的协调控制是一个困难且重要的问题。针对此问题,基于电-热-力多场耦合分析理论和晶粒尺寸演变模型,建立了大规格气阀电镦成形过程有限元模型;设计了电流和镦粗力的多级加载路径,研究了不同加载模式对电镦成形件的形状、温度和晶粒尺寸的影响规律。结果表明,增大电流可使温度显著升高,进而导致晶粒粗化,而较大的镦粗力可使温度降低,从而起到细化晶粒的作用。通过协调电流和镦粗力的峰值位置和水平可获得形状圆滑、晶粒细小的电镦件。此外,基于BP神经网络模型和案例推理方法,开发了大规格气阀电镦工艺加载模式设计系统,实现了电镦工艺参数加载模式的智能化设计。

关键词：气阀电镦组织演化参数加载路径多场多尺度耦合

转速及倾角对组合桨功率和微观混合性能影响研究

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高技术通讯 2024年第9期34卷 995-1002页

作者：范玉涛陈律名江兆陈冰冰浙江工业大学化工机械设计研究所杭州310023 浙江工业大学机械工程学院杭州310023 浙江工业大学过程装备及其再制造教育部工程研究中心杭州310023 上海通华不锈钢压力容器工程有限公司上海200000

为了研究多层搅拌桨片倾斜角度以及转速对反应器功率和微观混合性能的影响规律,对装配不同多层搅拌桨的搅拌反应器内的流体流动和微观混合性能进行了实验和数值模拟研究,在反应器内引入碘化物-碘酸盐平行竞争反应体系来评估搅拌釜内的... 详细信息

为了研究多层搅拌桨片倾斜角度以及转速对反应器功率和微观混合性能的影响规律,对装配不同多层搅拌桨的搅拌反应器内的流体流动和微观混合性能进行了实验和数值模拟研究,在反应器内引入碘化物-碘酸盐平行竞争反应体系来评估搅拌釜内的微观混合性能。此外,提出了表征反应器微观混合性能的离集指数(X_(S))和流场湍流特性之间的关联式,结果表明,模拟值与实验值吻合程度较高。当叶片倾角较小(φ≤30°)时,叶片倾角对釜内微观混合性能影响较小;而当叶片倾角较大(φ≥45°)时,釜内微观混合性能随叶片倾角的增加而显著减小。X_(S)与log(ε)之间基本呈线性关系。

关键词：搅拌釜化学反应计算流体力学(CFD) 微观混合

Large Deviations for Parameter Estimators of Some Time Inhomogeneous Diffusion Process

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Acta Mathematica Sinica,English Series 2011年第11期27卷 2245-2258页

作者： Shou jiang zhao Fu Qing GAO School of Mathematics and Statistics Wuhan University Wuhan 430072 P. R. China School of Science China Three Gorges University Yichang 443002 P. R. China

The goal of this paper is to study large deviations for estimator and score function of some time inhomogeneous diffusion process. Large deviation in the non-steepness case with explicit rate functions is obtained by ... 详细信息

关键词： Parameter estimation large deviations time inhomogeneous diffusion process

Positioning a fluorescent probe at the core of a glassy star polymer for detection of local dynamics

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Chinese Chemical Letters 2018年第3期29卷 374-380页

作者： Desheng Li Jingfa Yang jiang zhao Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

Accessing local dynamics within a single macromolecule is the key to understand the physical origin of the viscoelasticity and especially the glass transition. In order to extract specific information on the dynamics of the branch point of a star polymer around its glass transition temperature, four-arm star poly （n-butyl methacrylate） with a fluorescent core was synthesized using perylene diimide as initiator and polymerization conducted via atom transfer radical polymerization. The process is found to be effective in positioning the fluorophore at the branch point with the fluorophore intact, which allows the successful application of single molecule fluorescence defocus imaging in examining the local site- sensitive dynamics. The power spectra of rotation trajectories, the population of rotating fluorophores as well as the distribution of angular displacement were used to revel the difference in local dynamics between branch point and the arm＇s end. It is discovered that the local dynamics at the core of the star polymer is much less activated than that at the arm＇s end. The results demonstrate the strong effect dues to the topological constrain at the branch point and the more free space at the arm＇s end.

关键词： Perylene diimide Star polymer Glass transition Fluorescence defocus imaging Local dynamics