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Repair tolerance assessment for aircraft composite structures using Bayesian updating

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Chinese Journal of Aeronautics 2024年第6期37卷 360-391页

作者： Xin LI Hongfu zuo Bin YANG School of Automotive and Rail Transit Nanjing Institute of TechnologyNanjing 211167China Civil Aviation Key Laboratory of Aircraft Health Monitoring and Intelligent Maintenance College of Civil AviationNanjing University of Aeronautics and AstronauticsNanjing 211106China

Detection and repair of composite damage is crucial to ensure the safety and reliability of aircraft structures.A novel approach to quantitatively evaluate the repair tolerance of composite structures in civil aircraft based on Bayesian updating is *** method incorporates historical damage inspection data to determine the prior distribution of damage size,which is then updated with newly collected damage size data using Bayesian *** Carlo simulation is employed to investigate the probability of failure and estimate maintenance costs,considering various factors such as the frequency and timing of damage events,damage detection,structural strength,gust loads,and maintenance expenses throughout the lifecycle of composite *** and economic factors are considered to establish a lower threshold for repairs and an upper threshold for maintenance based on the occurrence of accidental impact *** of the effectiveness and feasibility of a quantitative assessment method for repair tolerance is conducted using damage statistics data from civil aircraft routes utilizing the structural skin panels of composite outer *** results demonstrate that the method proposed in conjunction with extensive simulations and full utilization of field damage inspection data can effectively simulate unexpected impact damage situations that may occur during civil aircraft service and evaluate the reliability and economic feasibility of the repair of *** research findings hold significant theoretical and practical value for the preparation of documents for continued airworthiness of composite structures,including structural repair manuals and maintenance programs.

关键词： Composite structures Repair tolerance Maintenance Bayesian updating Probability of failure

Motion-pressure coupled control and simulation of long-endurance capability for multicapsule stratospheric airships

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Chinese Journal of Aeronautics 2024年第6期37卷 137-150页

作者： Zhiguang SHI Wei HUO Zongyu zuo School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Beijing Near Space Airship Technology Development Co. LtdBeijing 100070China

The current study focuses on the motion-pressure coupled control for a multicapsule stratospheric airship and transforms the path-tracking and heading-hold control of airships into guidance tracking with a time-varying weighted sum of longitudinal and lateral velocities by the definition of compound ***,an improved nonlinear predictive control method is provided to reduce the control energy consumption by the rolling optimization of controller parameters based on finite time intervals,ensuring infinite-time path-tracking ***,combined with the proposed cyclic regulation process of safe pressure between internal and external capsules,this study can fully reflect the force-thermal coupled rule of airships under the actions of atmospheric environment and maneuvering force,while evaluating the long-endurance capability of airships under the conditions of safe superheating and *** effectiveness of the motionpressure coupled controller was verified through numerical simulations,which can overcome the influence of environmental wind and achieve a tracking effect for the desired cruise path and compound *** airspeed provided during the cyclic circadian time caused the maximum superheating of the helium controlled within 30*** helium in the internal and external capsules achieved circadian *** equivalent micropore diameter of the capsule of 5 mm can achieve 55 days of long-endurance *** controller satisfies the requirements of cruise-flight application modes for multicapsule stratospheric airships with important engineering value.

关键词： Compound speed Nonlinear predictive control Cyclic pressure regulation Long-endurance capability Stratospheric airship

A Novel Prescribed-Performance Path-Following Problem for Non-Holonomic Vehicles

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1476-1484页

作者： Zirui Chen Jingchuan Tang Zongyu zuo Seventh Research Division Beihang University(BUAA)Beijing 100191China IEEE

The issue of achieving prescribed-performance path following in robotics is addressed in this paper,where the aim is to ensure that a desired path within a specified region is accu-rately converged to by the controlled *** this context,a novel form of the prescribed performance guiding vector field is introduced,accompanied by a prescribed-time sliding mode con-trol ***,the interdependence among the pre-scribed parameters is *** validate the effectiveness of the proposed method,numerical simulations are presented to demonstrate the efficacy of the approach.

关键词： Guiding vector field non-holonomic vehicle path following prescribed performance sliding mode control

Single and combined effects of secondary polyethylene microplastic on the growth of Pak choi and the soil microbiome composition

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Frontiers of Environmental Science & Engineering 2024年第5期18卷 1-12页

作者： Jiamin Hu Zhenwen Xie Jiane zuo State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing100084China Tsinghua Shenzhen International Graduate School Tsinghua UniversityShenzhen518055China

It has been confirmed that microplastics(MPs)are present in the *** study simulated secondary PE-MPs via aging and mechanical processes to evaluate their effects on Pak choi(Brassica rapa L.)over 21 *** common pollutants,dichlorodiphenyltrichloroethane(DDT)and naphthalene,were used in the combined toxicity *** results indicated that the growth of Pak choi was significantly inhibited after exposure to secondary PE-MPs,and the combined effects were antagonistic,owing to the adsorption capacity of secondary PE-MPs to DDT and *** stress in Pak choi can be markedly affected,leading to oxidative damage to plant *** moisture content,soil bulk density,soil density,cation exchange capacity(CEC),and FDA hydrolase in the planted soils increased in the treated groups,and the TOC content changed *** also found that the microbial composition of the soil in the DDT and naphthalene groups showed more significant alterations than that in the other *** diversity analysis showed that species diversity increased in the combined groups but indicated a clear downward trend in the single MPs *** study suggests that secondary PE-MPs harm the growth of Pak choi and can change soil properties,revealing the harm to the ecosystem of MPs in the soil.

关键词： Secondary PE-MPs Combined effects Oxidative stress Soil properties Bacterial community

政府创新投入可以促进市场创新投入吗——基于我国内地63所教育部直属高校科技创新数据的实证研究

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科技进步与对策 2022年第8期39卷 10-18页

作者：周志远左月华邹宇湖北省人民政府办公厅湖北武汉430071 华中科技大学经济学院湖北武汉430074 浙江核新同花顺网络信息股份有限公司浙江杭州310000

高校是我国重要的创新研发主体,高校经费主要来源于政府和市场,这两种异质性研发创新投入关系值得关注。选取2005-2018年我国内地63所教育部直属高校科技创新数据,采用面板VAR模型和个体固定效应模型,从动态和静态两个方面对高校科技创... 详细信息

高校是我国重要的创新研发主体,高校经费主要来源于政府和市场,这两种异质性研发创新投入关系值得关注。选取2005-2018年我国内地63所教育部直属高校科技创新数据,采用面板VAR模型和个体固定效应模型,从动态和静态两个方面对高校科技创新投入中政府创新投入与市场创新投入的关系进行实证检验。结果发现,在高校科技创新活动中,政府创新投入对市场创新投入存在积极影响,这种促进作用存在两期左右的滞后期,且只在短期内显著;从长期看,政府投入对市场投入的促进作用不显著。

关键词：政府创新投入市场创新投入高校科技创新信号效应知识溢出效应

转板对高新技术企业创新的影响--基于融资约束视角

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财经论丛 2022年第2期 38-47页

作者：左月华刘蒙刘晓军华中科技大学经济学院湖北武汉430074

我国资本市场不同板块间转板制度的缺失不利于支持高新技术企业发展。本文以新三板高新技术企业为样本,利用倾向得分匹配和倍差法结合的方法进行实证检验,考察新三板高新技术企业的成功转板能否促进创新及其背后的作用机制。实证结果表... 详细信息

我国资本市场不同板块间转板制度的缺失不利于支持高新技术企业发展。本文以新三板高新技术企业为样本,利用倾向得分匹配和倍差法结合的方法进行实证检验,考察新三板高新技术企业的成功转板能否促进创新及其背后的作用机制。实证结果表明,新三板高新技术企业转板进入场内市场可显著促进企业创新。机制检验表明,转板会通过放松企业融资约束的方式来促进企业创新,具体包括企业的股票流动性、“上市信用”认可和营运资金稳定性三个渠道。

关键词：新三板高新技术企业转板倾向得分匹配倍差法融资约束创新

Three-dimensional limit variation analysis on the ultimate pullout capacity of the anchor cables based on the Hoek-Brown failure criterion

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Journal of Mountain Science 2024年第3期21卷 1036-1047页

作者： zuo Shi ZHAO Lianheng HU Shihong College of Civil Engineering Changsha UniversityChangsha 410022China Hunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering Structure Key Laboratory of Heavy-Haul Railway Engineering StructureMinistry of EducationCentral South UniversityChangsha 410075China College of Civil Engineering Central South UniversityChangsha 410075China

Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous *** study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock *** three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis *** numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in *** results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.

关键词： Anchor cable Ultimate pullout capacity(UPC) Failure model Variation analysis Hoek-Brown failure criterion

An Improved UNet Lightweight Network for Semantic Segmentation of Weed Images in Corn Fields

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Computers, Materials & Continua 2024年第6期79卷 4413-4431页

作者： Yu zuo Wenwen Li School of Information and Control Engineering Jilin Institute of Chemical TechnologyJilin132022China School of Mechanical and Control Engineering Baicheng Normal UniversityBaicheng137000China

In cornfields,factors such as the similarity between corn seedlings and weeds and the blurring of plant edge details pose challenges to corn and weed *** addition,remote areas such as farmland are usually constrained by limited computational resources and limited collected ***,it becomes necessary to lighten the model to better adapt to complex cornfield scene,and make full use of the limited data *** this paper,we propose an improved image segmentation algorithm based on ***,the inverted residual structure is introduced into the contraction path to reduce the number of parameters in the training process and improve the feature extraction ability;secondly,the pyramid pooling module is introduced to enhance the network’s ability of acquiring contextual information as well as the ability of dealing with the small target loss problem;and lastly,Finally,to further enhance the segmentation capability of the model,the squeeze and excitation mechanism is introduced in the expansion *** used images of corn seedlings collected in the field and publicly available corn weed datasets to evaluate the improved *** improved model has a total parameter of 3.79 M and miou can achieve 87.9%.The fps on a single 3050 ti video card is about *** experimental results show that the network proposed in this paper can quickly segment corn weeds in a cornfield scenario with good segmentation accuracy.

关键词： Semantic segmentation deep learning UNet pyramid pooling module

A Dual-Task Learning Approach for Bearing Anomaly Detection and State Evaluation of Safe Region

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 229-241页

作者： Yuhua Yin Zhiliang Liu Bin Guo Mingjian zuo School of Mechanical and Electrical Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Qingdao International Academician Park Research Institute Qingdao 266041China

Predictive maintenance has emerged as an effective tool for curbing maintenance costs,yet prevailing research predominantly concentrates on the abnormal *** the ostensibly stable healthy phase,the reliance on anomaly detection to preempt equipment malfunctions faces the challenge of sudden anomaly *** address this challenge,this paper proposes a dual-task learning approach for bearing anomaly detection and state evaluation of safe *** proposed method transforms the execution of the two tasks into an optimization issue of the hypersphere *** leveraging the monotonicity and distinguishability pertinent to the tasks as the foundation for optimization,it reconstructs the SVDD model to ensure equilibrium in the model’s performance across the two *** experiments verify the proposed method’s effectiveness,which is interpreted from the perspectives of parameter adjustment and enveloping *** the meantime,experimental results also show two deficiencies in anomaly detection accuracy and state evaluation *** theoretical analysis inspires us to focus on feature extraction and data collection to achieve *** proposed method lays the foundation for realizing predictive maintenance in a healthy stage by improving condition awareness in safe regions.

关键词： Bearing condition monitoring Anomaly detection Safe region Support vector data description