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Numerical study of the effect of fatigue on impact performance of RC beams

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Science China(Technological Sciences) 2023年第2期66卷 346-362页

作者： LI Jie hao YiFei LIU ChunYuan XIAO dandan School of Civil Engineering Tianjin UniversityTianjin 300350China Tianjin Key Laboratory of Prefabricated Buildings and Intelligent Construction Hebei University of TechnologyTianjin 300401China

Some existing concrete structures not only face threats of possible explosions and impact,but also suffer from long-term fatigue loads induced by traffic or vibration of machines.Researchers have conducted extensive investigations on concrete structures against highly dynamic load,e.g.,blast or impact.However,the fatigue damage and performance deterioration of flexural members due to long-term cyclic loads throughout the service life have not been considered in the analysis of structures against highly dynamic loads.Studies have proven that fatigue damage resulted in degradation of concrete strength and modulus of elasticity(MoE),as well as a reduction in the strength of steel bars.The deteriorated materials caused a reduction in the residual capacity and stiffness of reinforced concrete(RC)structures under quasi-static loads.Therefore,ignoring the effect of fatigue may result in an overestimation of the performance of existing structures against blast or impact loads.This study numerically investigates the effect of fatigue on the impact performance of RC beams.The grid section method(GSM)is proposed to simulate RC beams with fatigue damage.The GSM is applied to divide the RC beam into compressive and tensile zones and assign deteriorated strength and MoE of concrete to corresponding zones according to the stress level.Numerical models of the RC beam with fatigue damage are established using LS-DYNA and validated against experimental results.The effect of different factors,including fatigue cycles,reinforcement ratio,concrete strength,and impact energy,on the impact behavior of RC beams is examined.Based on the results,the correction method is proposed to take into consideration of the fatigue damage in the estimation of RC beams against highly dynamic load.

关键词： impact fatigue grid section method numerical study

Air-stable synaptic devices based on bismuth triiodide and carbon nanotubes

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Nano Research 2022年第6期15卷 5435-5442页

作者： Dandan Hao Junyao Zhang Li Li Ben Yang Pu Guo Shiqi Zhang Jia Huang Interdisciplinary Materials Research Center School of Materials Science and EngineeringFrontiers Science Center for Intelligent Autonomous SystemsTongji UniversityShanghai 201804China Translational Research Institute of Brain and Brain-Like Intelligence Shanghai Fourth People’s Hospital Affiliated to Tongji UniversitySchool of Materials Science and EngineeringTongji UniversityShanghai 200434China

Artificial synaptic devices with the functions of emulating important biological synaptic behaviors are playing an increasingly important role in the development of neuromorphic computing systems.Single-walled carbon nanotubes(SWCNTs)with excellent electrical properties and high stability have been studied as active materials for synaptic devices.However,the performance of optical synaptic devices(OSDs)based on pure SWCNTs is limited by the weak light absorption property.Herein,bismuth triiodide(BiI_(3)),an environmentally stable and friendly optoelectronic material,is firstly combined with SWCNTs to fabricate OSDs with decent properties of perceiving and memorizing optical information.The OSDs can exhibit typical synaptic behaviors including excitatory postsynaptic current,paired-pulse facilitation,and short/long-term memory.Distinctively,the photoresponse of the OSD is independent of pulse light wavelength in the range of 365 to 650 nm,different from most of the previously reported OSDs,which usually have wavelength-dependent photo-response.Temperature-dependent photo-response behaviors of the devices are investigated.Importantly,the OSD without encapsulation holds good excitatory post-synaptic current(EPSC)behavior after being stored in the ambient environment for 170 days,indicating reliable environmental stability.Furthermore,an OSD array with nine synaptic devices is employed to mimic the human visual perception and memory functions.These results suggest the feasibility of BiI3/SWCNTs-based OSDs for the simulation of human visual memory.

关键词： semiconducting single-walled carbon nanotubes bismuth triiodide optical synaptic devices stability human visual memory

Bactericidal efficacy of slightly acidic electrolyzed water(SAEW)against Listeria monocytogenes planktonic cells and biofilm on food-contact surfaces

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Food Quality and Safety 2022年第2期6卷 225-233页

作者： Jianxiong hao Junyi Zhang Xueqi Zheng dandan Zhao College of Food Science and Biology Hebei University of Science and TechnologyShijazhuangChina

In the present study,the bactericidal efficacy of slightly acidic electrolyzed water(SAEW)against Listeria monocytogenes(L.monocytogenes)planktonic cells and biofilm on food-contact surfaces including stainless steel and glass was systematically evaluated.The results showed that SAEW(pH 5.09 and available chlorine concentration(ACC)of 60.33 mg/L)could kill L.monocytogenes on food-contact surfaces completely in 30 s,a disinfection efficacy equal to that of NaCIO solutions(pH 9.23 and ACC of 253.53 mg/L).The results showed that long exposure time and high ACC contributed to the enhancement of the disinfection efficacy of SAEW on L.monocytogenes on food-contact surfaces.Moreover,the log reduction of SAEW treatment presented an increasing tendency within the prolonging of treatment time when SAEW was used to remove the L.monocytogenes bioflm formed on stainless steel and glass surfaces,which suggested that SAEW could remove L.monocytogenes bio-film effectively and its disinfection efficacy is equal to(in the case of stainless steel)or higher than(in the case of glass)that of high-ACC NaCIO solutions.In addition,the results of the crystal violet staining and scanning electron microscopy also demonstrated that SAEW treatment could remove the L.monocytogenes biofilm on food-contact surfaces.

关键词： Slightly acidic electrolyzed water Listeria monocytogenes,biofilm food-contact surface

Monolayer molecular crystals for low-energy consumption optical synaptic transistors

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Nano Research 2022年第8期15卷 7639-7645页

作者： Zhekun Hua Ben Yang Junyao Zhang Dandan Hao Pu Guo Jie Liu Lang Jiang Jia Huang Interdisciplinary Materials Research Center School of Materials Science and EngineeringFrontiers Science Center for Intelligent Autonomous SystemsTongji UniversityShanghai 201804China Beijing National Laboratory for Molecular Sciences Key Laboratory of Organic SolidsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China Translational Research Institute of Brain and Brain-Like Intelligence Shanghai Fourth People's Hospital Affiliated to Tongji UniversitySchool of Materials Science and EngineeringTongji UniversityShanghai 200434China

Artificial synaptic devices hold great potential in building neuromorphic computers.Due to the unique morphological features,twodimensional organic semiconductors at the monolayer limit show interesting properties when acting as the active layers for organic field-effect transistors.Here,organic synaptic transistors are prepared with 1,4-bis((5’-hexyl-2,2’-bithiophen-5-yl)ethyl)benzene(HTEB)monolayer molecular crystals.Functions similar to biological synapses,including excitatory postsynaptic current(EPSC),pair-pulse facilitation,and short/long-term memory,have been realized.The synaptic device achieves the minimum power consumption of 4.29 fJ at low drain voltage of−0.01 V.Moreover,the HTEB synaptic device exhibits excellent long-term memory with 109 s EPSC estimated retention time.Brain-like functions such as dynamic learning-forgetting process and visual noise reduction are demonstrated by nine devices.The unique morphological features of the monolayer molecular semiconductors help to reveal the device working mechanism,and the synaptic behaviors of the devices can be attributed to oxygen induced energy level.This work shows the potential of artificial neuroelectronic devices based on organic monolayer molecular crystals.

关键词： monolayer molecular crystals synaptic devices organic field-effect transistors optical synaptic transistors

Lead-free perovskites-based photonic synaptic devices with zero electric energy consumption

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Science China(Information Sciences) 2024年第6期67卷 433-441页

作者： Dandan Hao Di YANG Haixia LIANG Jia HUANG Fukai SHAN College of Electronics and Information Qingdao University Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of Sciences School of Materials Science and Engineering Tongji University National Key Laboratory of Autonomous Intelligent Unmanned Systems Tongji University

The von Neumann bottleneck is a critical limitation in synaptic devices. Therefore, artificial synaptic devices resembling biological neuromorphic synapses have been developed to overcome the von Neumann bottleneck. However, synaptic devices require voltages, which results in considerable energy consumption. Here, photonic synaptic devices with the vertical structure of indium tin oxide(ITO)/SnO2/Al2O3/CsBi3I10/Au are fabricated, which can work in the self-powered mode owing to the photovoltaic effect endowed by a vertical multilayer structure. Several fundamental synaptic functions, such as excitatory postsynaptic current, paired-pulse facilitation, short-term plasticity(STP), long-term plasticity(LTP), pulse-frequency-dependent plasticity, transition of STP to LTP, and the learning experience are emulated. Moreover, Morse-coded external light information is decoded by self-powered photonic synaptic devices. The results indicate that self-powered photonic synaptic devices based on lead-free perovskites exhibit great potential for efficient neuromorphic computing and optical wireless communication.

关键词： photonic synaptic devices lead-free perovskites zero energy consumption synaptic plasticity Morse code

Reliability Analysis of Heterogeneous Sensor-Cloud Systems against Targeted Attacks

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China Communications 2022年第8期19卷 181-197页

作者： hao Peng Zhen Qian Guangquan Xu Kejie Mao Kangtian Li dandan Zhao Department of Computer Science and Engineering Zhejiang Normal UniversityJinhua Zhejiang 321004China Key Laboratory of Intelligent Education Technology and Application of Zhejiang Province Zhejiang Normal UniversityJinhua Zhejiang 321004China The Big Data School Qingdao Huanghai UniversityQingdao Shandong 266427China College of Intelligence and Computing Tianjin UniversityTianjin 300072China

Based on the wide application of cloud computing and wireless sensor networks in various fields,the Sensor-Cloud System(SCS)plays an indispensable role between the physical world and the network world.However,due to the close connection and interdependence between the physical resource network and computing resource network,there are security problems such as cascading failures between systems in the SCS.In this paper,we propose a model with two interdependent networks to represent a sensor-cloud system.Besides,based on the percolation theory,we have carried out a formulaic theoretical analysis of the whole process of cascading failure.When the system’s subnetwork presents a steady state where there is no further collapse,we can obtain the largest remaining connected subgroup components and the penetration threshold.Theoretically,this result is the critical maximum that the coupled SCS can withstand.To verify the correctness of the theoretical results,we further carried out actual simulation experiments.The results show that a scale-free network priority attack’s percolation threshold is always less than that of ER network which is priority attacked.Similarly,when the scale-free network is attacked first,adding the power law exponentλcan be more intuitive and more effective to improve the network’s reliability.

关键词： sensor-cloud systems targeted attacks heterogeneous networks reliability analysis system security

A Security Enhancement Model Based on Switching Edge Strategy in Interdependent Heterogeneous Cyber-Physical Systems

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China Communications 2022年第2期19卷 158-173页

作者： dandan Zhao Can Liu Guangquan Xu Zhiguo Ding hao Peng Juan Yu Jianmin Han Zhejiang Normal University Jinhua 321004China Qingdao Huanghai University Qingdao 266427China Tianjin University Tianjin 300350China Key Laboratory of Intelligent Education Technology and Application of Zhejiang Province Zhejiang Normal UniversityJinhua 321004China

With the advent of cross-domain interconnection,large-scale sensor network systems such as smart grids,smart homes,and intelligent transportation have emerged.These complex network systems often have a CPS(Cyber-Physical System)architecture and are usually composed of multiple interdependent systems.Minimal faults between interdependent networks may cause serious cascading failures between the entire system.Therefore,in this paper,we will explore the robustness detection schemes for interdependent networks.Firstly,by calculating the largest giant connected component in the entire system,the security of interdependent network systems under different attack models is analyzed.Secondly,a comparative analysis of the cascade failure mechanism between interdependent networks under the edge enhancement strategy is carried out.Finally,the simulation results verify the impact of system reliability under different handover edge strategies and show how to choose a better handover strategy to enhance its robustness.The further research work in this paper can also help design how to reduce the interdependence between systems,thereby further optimizing the interdependent network system’s structure to provide practical support for reducing the cascading failures.In the later work,we hope to explore our proposed strategies in the network model of real-world or close to real networks.

关键词： security enhancement switching edge strategy interdependent systems cyber-physical systems

LFM Radar Source Passive Localization Algorithm Based on Range Migration

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Journal of Beijing Institute of Technology 2024年第2期33卷 130-140页

作者： dandan Li Deyi Wang hao Huan Beijing Key Laboratory of Fractional Signals and Systems School of Information and ElectronicsBeijing Institute of TechnologyBeijing 100081China Beijing Aerospace Automatic Control Institute Beijing 100854China

Traditional single-satellite passive localization algorithms are influenced by frequency and angle measurement accuracies,resulting in error estimation of emitter position on the order of kilometers.Subsequently,a single-satellite localization algorithm based on passive synthetic aper-ture(PSA)was introduced,enabling high-precision positioning.However,its estimation of azimuth and range distance is considerably affected by the residual frequency offset(RFO)of uncoopera-tive system transceivers.Furthermore,it requires data containing a satellite flying over the radia-tion source for RFO search.After estimating the RFO,an accurate estimation of azimuth and range distance can be carried out,which is difficult to achieve in practical situations.An LFM radar source passive localization algorithm based on range migration is proposed to address the dif-ficulty in estimating frequency offset.The algorithm first provides a rough estimate of the pulse repetition time(PRT).It processes intercepted signals through range compression,range interpola-tion,and polynomial fitting to obtain range migration observations.Subsequently,it uses the changing information of range migration and an accurate PRT to formulate a system of nonlinear equations,obtaining the emitter position and a more accurate PRT through a two-step localization algorithm.Frequency offset only induces a fixed offset in range migration,which does not affect the changing information.This algorithm can also achieve high-precision localization in squint scenar-ios.Finally,the effectiveness of this algorithm is verified through simulations.

关键词： passive localization range migration residual frequency offset

Observation of CO2^++ dication in the dayside Martian upper atmosphere

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Earth and Planetary Physics 2020年第4期4卷 396-402页

作者： hao Gu Jun Cui dandan Niu LongKang Dai JianPing Huang XiaoShu Wu YongQiang hao Yong Wei State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao 999078China School of Atmospheric Sciences Sun Yat-Sen UniversityZhuhai Guangdong 519082China Key Laboratory of Lunar and Deep Space Exploration Chinese Academy of SciencesBeijing 100101China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China School of Earth and Space Sciences Beijing UniversityBeijing 100871China Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China School of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

Doubly charged positive ions(dications)are an important component of planetary ionospheres because of the large energy required for their formation.Observations of these ions are exceptionally difficult due to their low abundances;until now,only atomic dications have been detected.The Neutral Gas and Ion Mass Spectrometer(NGIMS)measurements made on board the recent Mars Atmosphere and Volatile Evolution mission provide the first opportunity for decisive detection of molecular dications,CO2^++in this case,in a planetary upper atmosphere.The NGIMS data reveal a dayside averaged CO2^++distribution declining steadily from 5.6 cm^−3 at 160 km to below 1 cm^−3 above 200 km.The dominant CO2^++production mechanisms are double photoionization of CO2 below 190 km and single photoionization of CO2^+at higher altitudes;CO2++destruction is dominated by natural dissociation,but reactions with atmospheric CO2 and O become important below 160 km.Simplified photochemical model calculations are carried out and reasonably reproduce the data at low altitudes within a factor of 2 but underestimate the data at high altitudes by a factor of 4.Finally,we report a much stronger solar control of the CO2^++density than of the CO2+density.

关键词： MAVEN Martian ionosphere dication