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A robust TDOA based solution for source location using mixed Huber loss

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Journal of Systems Engineering and Electronics 2021年第6期32卷 1375-1380页

作者： YOU Mingyi LU annan Science and Technology on Communication Information Security Control Laboratory No.36 Research Institute of China Elec-tronics Technology Group CorporationJiaxing 314033China No.36 Research Institute of China Electronics Technology Group Corporation Jiaxing 314033China

This paper proposes a source localization solution robust to measurement outliers in time differences of arrivals(TDOA)*** solution uses a piecewise loss function named as mixed Huber loss(MHL)proposed based on the classical Huber loss(HL)and its refined *** MHL is able to effectively mitigate the impact of all levels of measurement outliers by setting two triggering *** practice,appropriate triggering threshold values can be obtained through simulation given the level of measurement noise and a rough range of potential measurement outliers.A clustering based approach is proposed to further improve the robustness of localization solution against reference sensor related *** are included to examine the solution's performance and compare it with several *** proposed MHL based solution is shown to be superior to the classical solution and the *** solution is shown to be even robust to multiple measurement ***,the influence of range measurement outliers in the reference sensor can be effectively mitigated by the clustering based approach.

关键词： time differences of arrivals(TDOA) robust localization Huber loss(HL) outlier mitigation

Revising the unified hardening model by using a smoothed Hvorslev envelope

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 778-790页

作者： annan Zhou Yangping Yao School of Engineering Royal Melbourne Institute of Technology(RMIT) Department of Civil Engineering Beihang University

The original unified hardening(UH) model, in which a straight Hvorslev envelope was employed to determine the potential peak stress ratio of overconsolidated soils, is revised using a smoothed Hvorslev envelope(Hermite-Hvorslev envelope). The strength at the intersection between the straight Hvorslev envelope and the critical state surface(i.e. Mohr-Coulomb envelope) can be undefined due to the discontinuous change in the slope of the two linear strength envelopes mentioned above. A smoothed Hvorslev envelope is derived through Hermite interpolation to ensure a smooth change between the proposed Hvorslev envelope and the zero-tension surface as well as a smoothed transition between the proposed Hvorslev envelope and the critical state surface. The Hermite-Hvorslev envelope is then integrated into the original UH model, and then the UH models with four different functions of the Hvorslev envelope are compared with each other. The UH model revised by the Hermite-Hvorslev envelope can well predict the mechanical behaviors of normally consolidated and overconsolidated soils in drained and undrained conditions with the same parameters in the modified Cam-Clay model.

关键词： Constitutive model Clay Overconsolidation Hvorslev envelope Hermite interpolation

Constitutive model for overconsolidated clays

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Science China(Technological Sciences) 2008年第2期51卷 179-191页

作者： YAO YangPing HOU Wei ZHOU annan Department of Civil Engineering Beihang UniversityBeijing 100083China

Based on the relationships between the Hvorslev envelope,the current yield sur-face and the reference yield surface,a new constitutive model for overconsolidated clays is proposed. It adopts the unified hardening parameter,to which the potential failure stress ratio and the characteristic state stress ratio are introduced. The model can describe many characteristics of overconsolidated clays,including stress-strain relationships,strain hardening and softening,stress dilatancy,and stress path dependency. Compared with the Cam-clay model,the model only re-quires one additional soil parameter which is the slope of the Hvorslev envelope. Comparisons with data from triaxial drained compression tests for Fujinomori clay show that the proposed model can rationally describe overconsolidated properties. In addition,the model is also used to predict the stress-strain relationship in the isotropic consolidation condition and the stress paths in the undrained triaxial compression tests.

关键词： overconsolidated clays current yield surface reference yield surface unified hardening parameter Hvorslev envelope.

Consolidation of partially saturated ground improved by impervious column inclusion:Governing equations and semi-analytical solutions

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第3期14卷 837-850页

作者： Lei Wang annan Zhou Yongfu Xu Xiaohe Xia School of Urban Railway Transportation Shanghai University of Engineering ScienceShanghai201620China Civil and Infrastructure Engineering Discipline School of EngineeringRMIT UniversityMelbourne3001Australia Department of Civil Engineering Shanghai Jiao Tong UniversityShanghai200240China

This study focuses on the consolidation behavior and mathematical interpretation of partially-saturated ground improved by impervious column *** constitutive relations for soil skeleton,pore air and pore water for partially saturated soils are proposed in the context of partially-saturated ground improved by impervious column *** equation and dissipation equations of excess pore air/water pressures for a partially saturated improved ground are then *** semi-analytical solutions for ground settlement and pore pressure dissipation are then obtained through the Laplace transform and validated by the existing solutions for two special cases in the literature and the numerical results obtained from the finite difference method.A series of parametric studies is finally conducted to investigate the influence of some key factors on consolidation of partially saturated ground improved by impervious column *** on the parametric study,it can be found that a higher value of the area replacement ratio or modulus of the pile results in a longer dissipation time of excess pore air pressure(PAP),a shorter dissipation time of excess pore water pressure(PWP),and a lower normalized settlement.

关键词： Semi-analytical solution Consolidation Partially saturated soil Ground improvement Impervious column inclusion

Parameters Identification of Tunnel Jointed Surrounding Rock Based on Gaussian Process Regression Optimized by Difference Evolution Algorithm

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Computer Modeling in Engineering & Sciences 2021年第6期127卷 1177-1199页

作者： annan Jiang Xinping Guo Shuai Zheng Mengfei Xu Highway and Bridge Institute Dalian Maritime UniversityDalian116026China

Due to the geological body uncertainty,the identification of the surrounding rock parameters in the tunnel construction process is of great significance to the calculation of tunnel *** ubiquitous-joint model and three-dimensional numerical simulation have advantages in the parameter identification of surrounding rock with weak planes,but conventional methods have certain problems,such as a large number of parameters and large time *** solve the problems,this study combines the orthogonal design,Gaussian process(GP)regression,and difference evolution(DE)optimization,and it constructs the parameters identification method of the jointed surrounding *** calculation process of parameters identification of a tunnel jointed surrounding rock based on the GP optimized by the DE includes the following ***,a three-dimensional numerical simulation based on the ubiquitous-joint model is conducted according to the orthogonal and uniform design parameters combing schemes,where the model input consists of jointed rock parameters and model output is the information on the surrounding rock displacement and ***,the GP regress model optimized by DE is trained by the data ***,the GP model is integrated into the DE algorithm,and the absolute differences in the displacement and stress between calculated and monitored values are used as the objective function,while the parameters of the jointed surrounding rock are used as variables and *** proposed method is verified by the experiments with a joint rock surface in the Dadongshan tunnel,which is located in Dalian,*** obtained calculation and analysis results are as follows:CR=0.9,F=0.6,NP=100,and the difference strategy DE/Best/1 is *** results of the back analysis are compared with the field monitored values,and the relative error is 4.58%,which is *** algorithm influencing factors are also discussed,and it is found that the local correlation

关键词： Gauss process regression differential evolution algorithm ubiquitous-joint model parameter identification orthogonal design

Advances in understanding the mechanisms of Arctic amplification

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Science China Earth Sciences 2024年第12期67卷 3814-3829页

作者： Jiefeng LI Chuanfeng ZHAO annan CHEN Haotian ZHANG Yikun YANG Department of Atmospheric and Oceanic Sciences School of PhysicsPeking UniversityBeijing 100871China

The near-surface temperatures in the Arctic are increasing at more than twice the global average rate,a phenomenon known as Arctic amplification(AA).In recent years,numerous studies using ground-based and satellite observations,along with model simulations,have explored the potential mechanisms behind AA,offering a variety of observational evidence and theoretical *** the understanding of AA drivers has improved,significant uncertainties remain in quantifying the contributions of different influential *** the basis of the latest research,this article thoroughly examines the factors driving rapid warming in the Arctic,including local feedbacks,atmospheric circulation,ocean currents,and aerosols,and compares quantitative results across *** analysis highlights the complex interplay of multiple factors contributing to AA,with no clear consensus on the relative contributions of each ***,the article underscores key challenges in current research,emphasizing the need for more reliable observational data,a deeper understanding of AA mechanisms,improved model parameterizations,and the disentanglement of interactions among driving factors,all of which are essential for future investigations.

关键词： Arctic amplification Sea ice Driving mechanisms Local feedbacks Poleward transport

Discontinuous mechanical behaviors of existing shield tunnel with stiffness reduction at longitudinal joints

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Frontiers of Structural and Civil Engineering 2023年第1期17卷 37-52页

作者： Xiang LIU Qian FANG annan JIANG Dingli ZHANG Jianye LI Liaoning Key Laboratory of Marine Environmental Bridge and Tunnel Engineering Dalian Maritime UniversityDalian 116026China Key Laboratory for Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China

An analytical model is proposed to estimate the discontinuous mechanical behavior of an existing shield tunnel above a new tunnel. The existing shield tunnel is regarded as a Timoshenko beam with longitudinal joints. The opening and relative dislocation of the longitudinal joints can be calculated using Dirac delta functions. Compared with other approaches, our method yields results that are consistent with centrifugation test data. The effects of the stiffness reduction at the longitudinal joints (α and β), the shearing stiffness of the Timoshenko beam GA, and different additional pressure profiles on the responses of the shield tunnel are investigated. The results indicate that our proposed method is suitable for simulating the discontinuous mechanical behaviors of existing shield tunnels with longitudinal joints. The deformation and internal forces decrease as α, β, and GA increase. The bending moment and shear force are discontinuous despite slight discontinuities in the deflection, opening, and dislocation. The deflection curve is consistent with the additional pressure profile. Extensive opening, dislocation, and internal forces are induced at the location of mutation pressures. In addition, the joints allow rigid structures to behave flexibly in general, as well as allow flexible structures to exhibit locally rigid characteristics. Owing to the discontinuous characteristics, the internal forces and their abrupt changes at vulnerable sections must be monitored to ensure the structural safety of existing shield tunnels.

关键词： tunnel–soil interaction discontinuous analysis longitudinal joints existing shield tunnel Timoshenko beam Dirac delta function

Real-time analysis and prediction of shield cutterhead torque using optimized gated recurrent unit neural network

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第4期14卷 1232-1240页

作者： Song-Shun Lin Shui-Long Shen annan Zhou Department of Civil Engineering School of Naval ArchitectureOceanand Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Key Laboratory of Intelligent Manufacturing Technology Department of Civil and Environmental EngineeringCollege of EngineeringShantou UniversityShantou515063China Discipline of Civil and Infrastructure School of EngineeringRoyal Melbourne Institute of Technology(RMIT)MelbourneVictoria 3001Australia Department of Civil and Environmental Engineering National University of Singapore117576Singapore

An accurate prediction of earth pressure balance(EPB)shield moving performance is important to ensure the safety tunnel excavation.A hybrid model is developed based on the particle swarm optimization(PSO)and gated recurrent unit(GRU)neural *** is utilized to assign the optimal hyperparameters of GRU neural *** are mainly four steps:data collection and processing,hybrid model establishment,model performance evaluation and correlation *** developed model provides an alternative to tackle with time-series data of tunnel *** from that,a novel framework about model application is performed to provide guidelines in practice.A tunnel project is utilized to evaluate the performance of proposed hybrid *** indicate that geological and construction variables are significant to the model *** analysis shows that construction variables(main thrust and foam liquid volume)display the highest correlation with the cutterhead torque(CHT).This work provides a feasible and applicable alternative way to estimate the performance of shield tunneling.

关键词： Earth pressure balance(EPB)shield tunneling Cutterhead torque(CHT)prediction Particle swarm optimization(PSO) Gated recurrent unit(GRU)neural network

Generalized non-linear strength theory and transformed stress space

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Science China(Technological Sciences) 2004年第6期47卷 691-709页

作者： YAO Yangping LU Dechun ZHOU annan ZOU Bo Department of Civil Engineering Beihang UniversityBeijing 100083China

Based on the test data of frictional materials and previous research achievements in this field, a generalized non-linear strength theory (GNST) is proposed. It describes non-linear strength properties on the π-plane and the meridian plane using a unified formula, and it includes almost all the present non-linear strength theories, which can be used in just one material. The shape of failure function of the GNST is a smooth curve between the SMP criterion and the Mises criterion on the π-plane, and an exponential curve on the meridian plane. Through the transformed stress space based on the GNST, the combination of the GNST and various constitutive models using p and q as stress parameters can be realized simply and rationally in three-dimensional stress state. Keywords generalized non-linear strength theory (GNST) - transformed stress - constitutive model - application

关键词： generalized non-linear strength theory (GNST) transformed stress constitutive model application