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Efficient Inverse Method for Structural Identification Considering Modeling and Response Uncertainties

Chinese Journal of Mechanical Engineering 2022年第5期35卷 150-161页

作者： Lixiong Cao Jie Liu Cheng Lu Wei Wang State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

The inverse problem analysis method provides an effective way for the structural parameter ***,uncertainties wildly exist in the practical engineering inverse *** to the coupling of multi-source uncertainties in the measured responses and the modeling parameters,the traditional inverse method under the deterministic framework faces the challenges in solving mechanism and computing *** this paper,an uncertain inverse method based on convex model and dimension reduction decomposition is proposed to realize the interval identification of unknown structural parameters according to the uncertain measured responses and modeling ***,the polygonal convex set model is established to quantify the epistemic uncertainties of modeling ***,a space collocation method based on dimension reduction decomposition is proposed to transform the inverse problem considering multi-source uncertainties into a few interval inverse problems considering response *** transformed interval inverse problem involves the two-layer solving process including interval propagation and optimization *** order to solve the interval inverse problems considering response uncertainty,an efficient interval inverse method based on the high dimensional model representation and affine algorithm is further *** the coupling of the above two strategies,the proposed uncertain inverse method avoids the time-consuming multi-layer nested calculation procedure,and then effectively realizes the uncertainty identification of unknown structural ***,two engineering examples are provided to verify the effectiveness of the proposed uncertain inverse method.

关键词： Inverse problem Uncertainty quantification Dimension reduction decomposition Polygonal convex set Affine algorithm

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Enhancing Cross-Dataset Performance of Distracted Driving Detection With Score Softmax Classifier and Dynamic Gaussian Smoothing Supervision

IEEE Transactions on Intelligent Vehicles

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IEEE Transactions on Intelligent vehicles 2024年 1-14页

作者： Duan, Cong Liu, Zixuan Xia, Jiahao Zhang, Minghai Liao, Jiacai Cao, Libo State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha China Faculty of Engineering and IT University of Technology Sydney Australia College of Automotive and Mechanical Engineering Changsha China

Deep neural networks enable real-time monitoring of in-vehicle drivers, facilitating the timely prediction of distractions, fatigue, and potential hazards. This technology is now integral to intelligent transportation systems. Recent research has exposed unreliable cross-dataset driver behavior recognition due to a limited number of data samples and background noise. In this paper, we propose a Score-Softmax classifier, which reduces the model overconfidence by enhancing category independence. Imitating the human scoring process, we designed a two-dimensional dynamic supervisory matrix consisting of one-dimensional Gaussian-smoothed labels. The dynamic loss descent direction and Gaussian smoothing increase the uncertainty of training to prevent the model from falling into noise traps. Furthermore, we introduce a simple and convenient multi-channel information fusion method;it addresses the fusion issue among arbitrary Score-Softmax classification heads. We conducted cross-dataset experiments using the SFDDD, AUCDD, and the 100-Driver datasets, demonstrating that Score-Softmax improves cross-dataset performance without modifying the model architecture. The experiments indicate that the Score-Softmax classifier reduces the interference of background noise, enhancing the robustness of the model. It increases the cross-dataset accuracy by 21.34%, 11.89%, and 18.77% on the three datasets, respectively. The code is publicly available at https://***/congduan-HNU/SSoftmax. IEEE

关键词： Deep neural networks

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A novel imprecise stochastic process model for time-variant or dynamic uncertainty quantification

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Chinese Journal of Aeronautics 2022年第9期35卷 255-267页

作者： Jinwu LI Chao JIANG State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

This paper proposes a novel model named as “imprecise stochastic process model” to handle the dynamic uncertainty with insufficient sample information in real-world problems. In the imprecise stochastic process model, the imprecise probabilistic model rather than a precise probability distribution function is employed to characterize the uncertainty at each time point for a time-variant parameter, which provides an effective tool for problems with limited experimental samples. The linear correlation between variables at different time points for imprecise stochastic processes is described by defining the auto-correlation coefficient function and the crosscorrelation coefficient function. For the convenience of analysis, this paper gives the definition of the P-box-based imprecise stochastic process and categorizes it into two classes: parameterized and non-parameterized P-box-based imprecise stochastic processes. Besides, a time-variant reliability analysis approach is developed based on the P-box-based imprecise stochastic process model,through which the interval of dynamic reliability for a structure under uncertain dynamic excitations or time-variant factors can be obtained. Finally, the effectiveness of the proposed method is verified by investigating three numerical examples.

关键词： Dynamic reliability analysis Epistemic uncertainty Imprecise random variable Imprecise stochastic process P-box model Time-variant uncertainty

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A QoS-Aware DRL-Based Service Switching Approach for Vehicular Edge Computing

A QoS-Aware DRL-Based Service Switching Approach for Vehicul...

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2023 IEEE International Conference on Unmanned Systems, ICUS 2023

作者： Wang, Xiaowei Qiu, Zixian Li, Yang Qin, Hongmao Gao, Ming Wuxi Intelligent Control Research Institute of Hunan University State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Changsha China State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Changsha China

ISBN: (纸本)9798350316308

To meet the requirements of low latency and high reliability of vehicular computing, vehicular services need to be offloaded to multi-access edge computing (MEC) servers. However, due to the mobility of connected vehicles and the limited coverage of roadside units (RSUs), vehicular services need to be adaptively switched. In order to ensure the quality of service (QoS) in the process of vehicular service switching, a service switching approach based on deep reinforcement learning is proposed in this paper. Firstly, the optimization problem model is established by considering the QoS, service migration cost, and latency. Secondly, the problem is decomposed into several subproblems and transformed into Markov decision processes (MDPs). Finally, a deep reinforcement learning-based algorithm is employed to find the optimal service migration strategy. Simulation results indicate that the proposed approach can effectively ensure the QoS compared to the baseline approaches. © 2023 IEEE.

关键词： Quality of service

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An in-situ cross-linked network PMMA-based gel polymer electrolyte with excellent lithium storage performance

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Journal of Materials Science & technology 2024年第32期199卷 197-205页

作者： Shaopan Qin Min Wu Hongshun Zhao Jianbin Li Maoyin Yan Yurong Ren Yanli Qi School of Materials Science and Engineering Jiangsu Province Engineering Research Center of Intelligent Manufacturing Technology for the New Energy Vehicle Power BatteryChangzhou Key Laboratory of Intelligent Manufacturing and Advanced Technology for Power BatteryChangzhou UniversityChangzhou 213164China

Gel polymer electrolytes(GPEs)effectively combine the advantages of high ionic conductivity and re-duce the risk of leakage associated with *** this study,a chemically cross-linked gel polymer electrolyte was prepared by in-situ polymerization using polymethyl methacrylate(PMMA)as a matrix and neopentyl glycol diacrylate(NPGDA)as cross-linking *** cross-linked structure of the GPE was preliminarily investigated,as well as the influence of the degree of cross-linking on its phys-ical *** GPE exhibited a superior conductivity of 1.391 mS cm^(-1) at 25℃.Herein,the Li|GPE|LiNi_(0.8) Co_(0.1) Mn_(0.1) O_(2) cell has an excellent capacity retention rate of 80.7%after 150 cycles at 0.5 C in addition to a high discharge specific capacity of 203 mAh g^(-1).The structure of the cathode ma-terial is shielded from the production of byproducts during the charging and discharging of lithium-ion batteries by the cross-linked PMMA GPE.

关键词： Lithium-ion batteries In-suit polymerization Gel polymer electrolyte Polymethyl methacrylate Cross-linked network

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Revealing the grain size dependent hot workability and deformation mechanisms in a Mg-Zn-Y alloy

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Journal of Magnesium and Alloys 2023年第4期11卷 1461-1471页

作者： Ruiqing Lu Zhiming Xu Fulin Jiang Shiwei Xu Dingfa Fu Hui Zhang Jie Teng College of Materials Science and Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

Despite the industrial significance of grain size for enhancing mechanical properties and formability,the in-depth deformation mechanisms at elevated temperature are still *** investigate the functions of grain size on hot workability and deformation mechanisms,three groups of Mg-1.2Zn-0.2Y alloy specimens with different grain sizes were hot compressed and then studied by combining constitutive model,processing map and microstructural *** results showed that the enhanced hot workability accompanying low deformation activation energy and small instability regime was obtained with refined grain *** hot deformation,the decreased grain size in Mg1.2Zn-0.2Y alloy mainly improved the plastic deformation homogeneity,especially for the weakened local straining around grain *** a result,the dynamic recrystallization nucleation and texture development at lower strain level were influenced by the initial grain *** higher strain magnitude,the growth and coarsening of dynamic recrystallized grains would further release strain localization and improve hot workability,while the texture was less ***,unlike the primary basal slip and deformation twinning in the specimen with coarse grain at low temperature,non-basal slips of dislocations were initiated with less deformation twins in the specimens with refined grain size.

关键词： Mg-Zn-Y alloy Hot workability Plastic deformation Grain size Texture

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Finite element modeling and injury criteria investigation for the lower leg of the Chinese human body under impact loads

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Theoretical & Applied Mechanics Letters 2024年第4期14卷 259-269页

作者： Xianping Du Xizheng Zhao Jianyin Lei Guanjun Zhang School of Ocean Engineering and Technology Sun Yat-Sen UniversityZhuhai 519082China Institute of Applied Mechanics College of Mechanical and Vehicle EngineeringTaiyuan University of TechnologyTaiyuan 030024China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

The widely used human body injury criteria were established based on the biomechanical response of the EuroAmerican human body,without considering the differences in anthropometry and injury characteristics among different races,particularly the Chinese human body which typically has the smaller body *** absence of such race specific design considerations negatively influences the injury prevention capability for these populations,and weakens the applicability of injury *** resolve these issues,this study aims to develop a lower leg finite element model of a 50th percentile Chinese *** model is built based on the medical images of an average size Chinese male with detailed ankle ligaments and lower leg muscles *** from sixty experiments available in the literature are used to validate its *** the validated model,the lower leg model is subjected to combined axial compression and bending loads to evaluate its injury *** with a typical Euro-American human body mode,the Chinese lower leg presents reduced mechanical tolerance,and the revised tibia index may be an appropriate injury criteria for the Chinese lower ***,the validated model reproduces the pedestrian lower leg fracture in a domestic accident.

关键词： Chinese human body Lower limb model Impact load Injury tolerance Tibia index

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Tensile Properties and Wear Resistance of Mg Alloy Containing High Si as Implant Materials

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Journal of Renewable Materials 2023年第4期11卷 1977-1989页

作者： Mengqi Cong Yang Zhang Yunlong Zhang Xiao Liu Yalin Lu Xiaoping Li Key Laboratory of Advanced Materials Design and Additive Manufacturing of Jiangsu Province Jiangsu University of TechnologyChangzhou213001China

Magnesium alloy has been considered as one of the third-generation biomaterials for the regeneration and support of functional bone *** a regeneration implant material with great potential applications,in-situ Mg_(2)Si phase reinforced Mg-6Zn cast alloy was comprehensively studied and expected to possess excellent mechanical properties via the refining and modifying of Mg_(2)Si *** present study demonstrates that the primary and eutectic Mg_(2)Si phase can be greatly modified by the yttrium(Y)*** size of the primary Mg_(2)Si phases can be reduced to~20μm with an addition of 0.5 wt.%*** phenomenon is mainly attributed to the poisoning effect of the Y ***,wear resistance and tensile properties of the ternary alloy have also been improved by the Y ***-6Zn-4Si-0.5Y alloy exhibits optimal tensile properties and wears *** ultimate tensile strength and the elongation of the alloy with 0.5 wt.%Y are 50%and 65%higher than those of the ternary alloy,*** Y addition(1.0 wt.%)deteriorates the tensile properties of Mg-Zn-Si *** improvement of the tensile properties is mainly due to the modification of primary and eutectic Mg_(2)Si phases as well as the solid solution strengthening of the Y *** study provides a certain implication for the application of Mg-Zn-Si alloys containing Y elements as regeneration implants.

关键词： Magnesium alloys Mg2Si phase microstructure regeneration mechanical properties

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Unveiling deformation behavior and damage mechanism of irradiated high entropy alloys

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Journal of Materials Science & technology 2024年第29期196卷 71-87页

作者： Shuo Wang Yang Chen Jia Li Bin Liu Ruiqian Zhang Peter K Liaw Qihong Fang State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610213China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996USA

The oxide dispersion strengthening(ODS)high entropy alloy(HEA)exhibits the high elevated temperature performance and radiation resistance due to severe atomic lattice distortion and oxide particles dispersed in matrix,which is expected to become the most promising structural material in the next generation of nuclear energy ***,microstructure and damage evolution of irradiated ODS HEA under loading remain elusive at submicron scale using the existing simulations owing to a lack of atomic-lattice-distortion information from a micromechanics ***,the random field theory informed discrete dislocation dynamics simulations based on the results of high-resolution transmission electron microscopy are developed to study the dislocation behavior and damage evolution in ODS HEA considering the influence of severe lattice distortion and nanoscale oxide ***,the damage behavior shows an unusual trend of the decreasing-to-increasing transition with the continuous loading *** are two main types of damage micromechanics generated in irradiated ODS HEA:the dislocation loop damage in which the damage is controlled by irradiation-induced dislocation loops and their evolution,the strain localization damage in which the damage comes from the dislocation multiplication in the local plastic *** oxide particle hinders the dislocation movement in the main slip plane,and the lattice distortion induces the dislocation sliding to the secondary slip plane,which promotes the dislocation cross-slip and dislocation loop annihilation,and thus reduces the material damage in the elastic damage *** findings can deeply understand atomic-scale damage mechanism and guide the design of ODS HEA with high radiation resistance.

关键词： Oxide dispersion strengthening High entropy alloy Radiation Dislocation Damage model

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Acoustic fault signal extraction via the line-defect phononic crystals

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Frontiers of Mechanical Engineering 2022年第1期17卷 148-158页

作者： Tinggui CHEN Bo WU Dejie YU State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

Rotating machine fault signal extraction becomes increasingly important in practical engineering ***,fault signals with low signal-to-noise ratios(SNRs)are difficult to extract,especially at the early stage of fault *** this paper,2D line-defect phononic crystals(PCs)consisting of periodic acrylic tubes with slit are proposed for weak signal *** defect band,namely,the formed resonance band of line-defect PCs enables the incident acoustic wave at the resonance frequency to be trapped and enhanced at the resonance *** noise can be filtered by the band *** a result,fault signals with high SNRs can be obtained for fault feature *** effectiveness of weak harmonic and periodic impulse signal detection via line-defect PCs are investigated in numerical and experimental *** the numerical and experimental results indicate that line-defect PCs can be well used for extracting weak harmonic and periodic impulse *** work will provide potential for extracting weak signals in many practical engineering applications.

关键词： phononic crystals line-defect fault signal extraction acoustic enhancement

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