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Moment Redistribution Effect of the Continuous Glass Fiber Reinforced Polymer-Concrete Composite Slabs Based on Static Loading Experiment

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Structural Durability & Health Monitoring 2025年第1期19卷 105-123页

作者： zhao-Jun zhang Wen-Wei Wang Jing-Shui Zhen Bo-Cheng Li De-Cheng Cai Yang-Yang Du Hui Huang Offshore Oil Engineering Co.Ltd. Tianjin300461China Department of Bridge Engineering School of TransportationSoutheast UniversityNanjing211189China

This study aimed to investigate the moment redistribution in continuous glass fiber reinforced polymer(GFRP)-concrete composite slabs caused by concrete cracking and steel bar yielding in the negative bending moment *** experimental bending moment redistribution test was conducted on continuous GFRP-concrete composite slabs,and a calculation method based on the conjugate beam method was *** composite slabs were formed by combining GFRP profiles with a concrete layer and supported on steel beams to create two-span continuous composite slab *** methods,epoxy resin bonding,and stud connection,were used to connect the composite slabs with the steel *** experimental findings showed that the specimen connected with epoxy resin exhibited two moments redistribution phenomena during the loading process:concrete cracking and steel bar yielding at the internal *** contrast,the composite slab connected with steel beams by studs exhibited only one-moment redistribution phenomenon throughout the loading *** the concrete at the internal support cracked,the bending moment decreased in the internal support section and increased in the midspan *** the steel bars yielded,the bending moment further decreased in the internal support section and increased in the mid-span *** GFRP profiles do not experience cracking,there was no significant decrease in the bending moment of the mid-span *** test specimens experienced compressive failure of concrete at the mid-span *** results showed good agreement between the calculated and experimental values of bending moments in the mid-span section and internal support *** proposed model can effectively predict the moment redistribution behavior of continuous GFRP-concrete composite slabs.

关键词： Moment redistribution GFRP-concrete composite slabs bending moment experimental study analysis model

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Numerical Modeling of Friction Stir Welding Process by Using Rate-dependent Constitutive Model

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Journal of Materials Science & Technology 2007年第1期23卷 73-80页

作者： Hongwu zhang zhao zhang State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China

Rate-dependent constitutive model was used to simulate the friction stir welding process. The effect of the viscosity coefficient and the process parameters on the material behaviors and the stress distributions around the pin were studied. Results indicate that the stress in front of the pin is larger than that behind the pin. The difference between the radial/circumferential stress in front of the pin and that behind it becomes smaller when the material gets closer to the top surface. This difference increases with increasing the viscosity coefficient and becomes smaller when the welding speed decreases. The variation of the angular velocity does not significantly affect the difference.

关键词： Friction stir welding Finite element method Viscosity

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Fault detection and isolation for linear parameter-varying systems with time-delays: a geometric approach

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Science China(Information Sciences) 2023年第7期66卷 162-176页

作者： zhao zhang Xiao HE Department of Automation Tsinghua University

Fault detection and isolation(FDI) problems for linear parameter-varying(LPV) systems with state time-delays are studied in this paper. By defining the concept of unobservability subspace and designing its calculation algorithm, the geometric approach is introduced to the time-delay LPV systems. Utilizing Wirtinger-based integral inequality, we obtain a sufficient condition to solve the so-called H∞-based residual generation problem for the LPV systems. In this paper, we consider two cases: the time delay is known and the time delay is unknown but its estimated value can be obtained. Corresponding observers are proposed for both cases based on the geometric approach and H∞ techniques. Lyapunov-Krasovskii functional is utilized to handle the time-delays and Wirtinger’s inequality is employed to reduce conservatism. Numerical examples are presented to demonstrate the effectiveness of the proposed approach.

关键词： time-delay LPV systems geometric approach fault detection and isolation exact-memory rough-memory

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Resolution limit of mode-localised sensors

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Science China(Information Sciences) 2021年第4期64卷 198-207页

作者： zhao zhang Honglong CHANG Ministry of Education Key Laboratory of Micro/Nano Systems for Aerospace School of Mechanical EngineeringNorthwestern Polytechnical University

In recent years, the mode localisation phenomenon of weakly coupled resonators has been successfully utilised to improve the sensitivity of microelectromechanical system(MEMS) sensors. However,controversy remians about the resolution limits of mode-localised sensors. This paper asks two questions of the community: what are the resolution limits of the mode-localised sensors, and can the resolution improvement be obtained using mode-localised sensing? To answer these questions, we report a series of resolution models of mode-localised sensors. We conclude that mode-localised sensing can realise a higher measuring resolution by orders of magnitude when more than three resonators are weakly coupled, and this will lay the theoretical foundation for a breakthrough for the MEMS sensors industry.

关键词： MEMS mode-localised sensors resolution limit 2-degree-of-freedom higher degree-of-freedom

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CMOS phase-locked loops in ISSCC 2023

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Journal of Semiconductors 2023年第5期44卷 17-18页

作者： zhao zhang State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

High-performance phase-locked loops(PLL)are widely used in modern system-on chips(So C)including the ultrahigh-speed wireless/wireline communication(e.g.5G/6G transceivers,over-100-Gbps Ser Des transceivers),high resolution mm-wave radars,ultra-low power internet-of-thing(Io T),and high-sampling-rate data *** the 2023 IEEE International Solid-State Circuits Conference(ISSCC 2023).

关键词： ISSCC transceiver wireless

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A Variance Reducing Stochastic Proximal Method with Acceleration Techniques

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Tsinghua Science and Technology 2023年第6期28卷 999-1008页

作者： Jialin Lei Ying zhang zhao zhang School of Mathematical Science Zhejiang Normal UniversityJinhua 321004China

We consider a fundamental problem in the field of machine learning—structural risk minimization,which can be represented as the average of a large number of smooth component functions plus a simple and convex(but possibly non-smooth)*** this paper,we propose a novel proximal variance reducing stochastic method building on the introduced *** method achieves two proximal operator calculations by combining the fast Douglas–Rachford splitting and refers to the scheme of the FISTA algorithm in the choice of momentum *** show that the objective function value converges to the iteration point at the rate of O(1/k)when each loss function is convex and *** addition,we prove that our method achieves a linear convergence rate for strongly convex and smooth loss *** demonstrate the effectiveness of the proposed algorithm,especially when the loss function is ill-conditioned with good acceleration.

关键词： composite optimization Variance Reduction(VR) fast Douglas–Rachford(DR)splitting proximal operator

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Communication-efficient federated continual learning for distributed learning system with Non-IID data

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Science China(Information Sciences) 2023年第2期66卷 94-113页

作者： zhao zhang Yong zhang Da GUO Shuang zhao Xiaolin ZHU School of Electronic Engineering Beijing University of Posts and Telecommunications Beijing Key Laboratory of Work Safety Intelligent Monitoring Beijing University of Posts and Telecommunication

Due to the privacy preserving capabilities and the low communication costs, federated learning has emerged as an efficient technique for distributed deep learning/machine learning training. However, given the typical heterogeneous data distributions in the realistic scenario, federated learning faces the challenge of performance degradation on non-independent identically distributed(Non-IID) data across clients. Therefore, we propose federated continual learning to improve the performance on Non-IID data by introducing the knowledge of the other local models. Specifically, we propose a novel federated continual learning method called Fed SI, adapting the synaptic intelligence method to the federated learning scenario. Furthermore,in order to reduce the communication overheads, we propose the bidirectional compression and error compensation(BCEC) algorithm to produce the communication-efficient federated continual learning method,called CFedSI. Specifically, the proposed BCEC algorithm compresses both the uplink and the downlink transmission data and utilizes the error compensation locally to ensure training divergence. Experiments show that CFedSI improves the accuracy on Non-IID data by up to 46% with KDDCUP’99 dataset, 23%with CICIDS2017 dataset, 22% with MNIST dataset, and 8% with FashionMNIST dataset, along with the reduced communication overheads.

关键词： distributed learning system federated learning continual learning model compression error compensation

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Characteristic model-based H2/H∞ robust adaptive control during the re-entry of hypersonic cruise vehicles

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Science China(Information Sciences) 2015年第1期58卷 201-221页

作者： HUANG Huang zhang zhao Beijing Institute of Control Engineering Science and Technology on Space Intelligent Control Laboratory

This paper aims at introducing H2 and H∞robustness into the well-known characteristic modelbased golden-section adaptive control law, and applying the robust adaptive control scheme to the attitude control of hypersonic cruise vehicles that are subject to external disturbances and aerodynamic coefficients uncertainties. When maneuvering at ultra high speeds, the attitude system of the hypersonic cruise vehicle is extremely sensitive to external disturbances and aerodynamic coefficients variations, and therefore the adaptiveness and the robustness of the attitude system are crucial during the controller design. To enhance the robustness of the existing golden-section adaptive control law, a golden-section robust adaptive control law is proposed. Compared to the existing control law where the design of the parameter λ depends on experience and is carried out offline, linear matrix inequality-based synthesis of λ is proposed such that the closed-loop system is stable with guaranteed H2 and H∞performance. It is suitable for online computing and provides a time-varyingλ(k) that is adjusted towards the optimal H2 and H∞performance. When being applied to the attitude control of hypersonic vehicles during re-entry, the adaptive nature of the proposed control law provides the attitude system the capability to accommodate large flight conditions, and its H2 and H∞robustness brought by λ(k)guarantees satisfying tracking performance in the presence of disturbances including both external disturbance and absolute aerodynamic coefficients errors.

关键词： golden-section adaptive control characteristic model H2 and H∞analysis hypersonic vehicle attitude control

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From Liquid to Solid‑State Lithium Metal Batteries:Fundamental Issues and Recent Developments

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Nano-Micro Letters 2024年第2期16卷 68-125页

作者： zhao zhang Wei‑Qiang Han School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027People’s Republic of China

The widespread adoption of lithium-ion batteries has been driven by the proliferation of portable electronic devices and electric vehicles,which have increasingly stringent energy density *** metal batteries(LMBs),with their ultralow reduction potential and high theoretical capacity,are widely regarded as the most promising technical pathway for achieving high energy density *** this review,we provide a comprehensive overview of fundamental issues related to high reactivity and migrated interfaces in ***,we propose improved strategies involving interface engineering,3D current collector design,electrolyte optimization,separator modification,application of alloyed anodes,and external field regulation to address these *** utilization of solid-state electrolytes can significantly enhance the safety of LMBs and represents the only viable approach for advancing *** review also encompasses the variation in fundamental issues and design strategies for the transition from liquid to solid *** noteworthy is that the introduction of SSEs will exacerbate differences in electrochemical and mechanical properties at the interface,leading to increased interface inhomogeneity—a critical factor contributing to failure in all-solidstate lithium metal *** on recent research works,this perspective highlights the current status of research on developing high-performance LMBs.

关键词： Lithium metal batteries All-solid-state lithium metal battery Li dendrite Solid electrolyte Interface

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International Journal of Disaster Risk Science 2020年第4期11卷 466-483页

作者： Jing zhang zhao zhang Fulu Tao Key Laboratory of Environmental Change and Natural Hazards of the Ministry of Education Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China Institute of Geographical Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China

Rainfall-relatedhazards—deficitrainand excessive rain—inevitably stress crop production,and weather index insurance is one possible financial tool to mitigate such agro-metrological *** this study,we investigated where two rainfall-related weather indices—anomaly-based index(AI)and humidity-based index(HI)—could be best used for three main crops(rice,wheat,and maize)in China’s main agricultural zones.A county is defined as an“insurable county”if the correlation between a weather index and yield loss was *** maize-cropping counties,both weather indices identified more insurable counties for deficit rain than for excessive rain(AI:172 vs 63;HI:182 vs 68);moreover,AI identified lower basis risk for deficit rain in most agricultural zones while HI for excessive *** rice,the number of AIinsurable counties was higher than the number of HI-insurable counties for deficit rain(274 vs 164),but lower for excessive rain(199 vs 272);basis risks calculated by two weather indices showed obvious difference only in Zone ***,more wheat-insurable counties(AI:196 vs 71;HI:73 vs 59)and smaller basis risk indicate that both weather indices performed better for excessive rain in wheatplanting *** addition,most insurable counties showed independent yield loss,but did not necessarily result in effective risk *** study is a primary evaluation of rainfall-related weather indices for the three main crops in China,which will be significantly helpful to the agricultural insurance market and governments’policy making.

关键词： Agricultural insurance China Deficit rain Excessive rain Risk pooling Weather index

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