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Dynamic properties of low-density expandable polystyrene concrete materials

Defence Technology(防务技术) 2025年第1期43卷 94-108页

作者： Jue Han Hualin Fan Army Engineering University of PLA Nanjing 210007China Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Aerospace StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China Henan International Joint Laboratory of Dynamics of Impact and Disaster of Engineering Structures Department of Civil EngineeringNanyang Institute of TechnologyNanyang 473004China

Expanded polystyrene(EPS)concrete,known for its environmental friendliness,energy absorption capacity,and low impedance,has significant potential application in the fields of wave absorption and vibration *** study designed and prepared EPS concrete materials with four levels of ***-static uniaxial compression and Split Hopkinson Pressure Bar(SHPB)impact tests were conducted to obtain stress-strain curves,elastic moduli,failure modes,energy absorptions,and strain rate effects of the EPS concrete under quasi-static and dynamic loading *** influences of density on various performance indicators were *** combining the Zhu-Wang-Tang(ZWT)constitutive model with a modified elastic-brittle model,a modified dynamic constitutive model was *** accuracy of the model was validated by the experimental *** results indicate that the addition of EPS particles enhances the ductility of the EPS *** EPS concrete has significant strain rate effect,which gets stronger as density *** modifiedconstitutive model accurately characterizes the dynamic stress-strain curves of the EPS concrete.

关键词： EPS concrete Impact behavior Constitutive model SHPB test

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Inverse-time Backup Protection Based on Unified Characteristic Equation for Distribution Networks with High Proportion of Distributed Generations

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 202-212页

作者： Nana Chang Guobing Song Zhongxue Chang Yuping Zheng Xingang Yang the School of Electrical Engineering Xi’an Jiaotong UniversityXi’anChina State Key Laboratory of Smart Grid Protection and Control NARI Group CorporationNanjingChina Electric Power Research Institute of State Grid Shanghai Electric Power Company ShanghaiChina

The setting work of backup protection using steady-state current is tedious,and mismatches occasionally occur due to the increased proportion of distributed generations(DGs)connected to the power ***,there is a practical need to study a backup protection technology that does not require step-by-step setting and can be adaptively *** paper proposes an action sequence adaptive to fault positions that uses only positive sequence fault component(PSFC)*** the influence of DGs,the unified time dial setting can be obtained by selecting specific *** protection performance is improved by using the adjacent upstream and downstream protections to meet the coordination time interval in the case of metallic faults at the near-and far-ends of the ***,the expression and implementation scheme for inverse-time backup protection(ITBP)based on the unified characteristic equation is *** results show that this scheme can adapt to DG penetration scenarios and can realize the adaptive coordination of multi-level relays.

关键词： Inverse-time backup protection(ITBP) distributed generation(DG) positive sequence fault component(PSFC)voltage unified characteristic equation adaptive coordination

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High-speed train positioning based on a combination of Beidou navigation, inertial navigation and an electronic map

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Science China(Information Sciences) 2023年第7期66卷 237-252页

作者： Hui YANG Shuai-Qiang DONG Chun-Hua XIE School of Electrical and Automation Engineering East China Jiaotong University Key Laboratory of Advanced Control & Optimization of Jiangxi Province East China Jiaotong University State Key Laboratory of Performance Monitoring Protecting of Rail Transit Infrastructure East China Jiaotong University

To date, the studies on the combination positioning of high-speed trains have made great progress, but the positioning accuracy of these methods is relatively low. Map-matching positioning can improve positioning accuracy, but information transmission is time-consuming. Few studies incorporate it into combination positioning. To solve the problem, this paper proposes a high-speed train positioning method based on combining a Beidou navigation system, an inertial navigation system, and an electronic map. First, the combination positioning problem is transformed into a multi-objective optimization problem, which weights the direction similarity and distance error to form a fitness function and converts the railway line and the maximum error range of each positioning system into constraints. Second, an improved differential evolution algorithm is proposed to solve this problem. By referencing the gray wolf algorithm,the differential evolution algorithm updates individuals by varying toward the direction of multiple optimal values. Then, a new combination positioning algorithm for high-speed trains is proposed. In the simulation,the increase in positioning speed and accuracy is analyzed and validated. Compared to the current algorithms, the proposed algorithm performs better. The proposed method has practical value for improving the reliability and safety of train operations.

关键词： electronic map multi-objective optimization differential evolution algorithm Beidou navigation system high-speed train positioning

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An Aerial–Wall Robotic Insect That Can Land, Climb, and Take Off from Vertical Surfaces

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Research 2024年第1期2023卷 149-163页

作者： Qian Li Haoze Li Huan Shen Yangguang Yu Haoran He Xincheng Feng Yi Sun Zhiyuan Mao Guangming Chen Zongjun Tian Lida Shen Xiangming Zheng Aihong Ji College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjingChina College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjingChina State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjingChina

Insects that can perform flapping-wing flight,climb on a wall,and switch smoothly between the 2 locomotion regimes provide us with excellent biomimetic ***,very few biomimetic robots can perform complex locomotion tasks that combine the 2 abilities of climbing and ***,we describe an aerial–wall amphibious robot that is self-contained for flying and climbing,and that can seamlessly move between the air and *** adopts a flapping/rotor hybrid power layout,which realizes not only efficient and controllable flight in the air but also attachment to,and climbing on,the vertical wall through a synergistic combination of the aerodynamic negative pressure adsorption of the rotor power and a climbing mechanism with bionic adhesion *** the basis of the attachment mechanism of insect foot pads,the prepared biomimetic adhesive materials of the robot can be applied to various types of wall surfaces to achieve stable *** longitudinal axis layout design of the rotor dynamics and control strategy realize a unique cross-domain movement during the flying–climbing transition,which has important implications in understanding the takeoff and landing of ***,it enables the robot to cross the air–wall boundary in 0.4 s(landing),and cross the wall–air boundary in 0.7 s(taking off).The aerial–wall amphibious robot expands the working space of traditional flying and climbing robots,which can pave the way for future robots that can perform autonomous visual monitoring,human search and rescue,and tracking tasks in complex air–wall environments.

关键词： robot smoothly Vertical

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Ultralow-Energy-Barrier H_(2)O_(2)Dissociation on Coordinatively Unsaturated Metal Centers in Binary Ce-Fe Prussian Blue Analogue for Efficient and Stable Photo-Fenton Catalysis

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Energy & Environmental Materials 2023年第6期6卷 427-435页

作者： Wenting Zheng Hui Guo Changqing Zhu Cailiang Yue Wenlei Zhu Fuqiang Liu Zhaoxu Chen State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China Institute of Theoretical and Computational Chemistry Key Laboratory of Mesoscopic Chemistry of MOESchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

The low intrinsic activity of Fenton catalytic site and high demand for light-energy input inhibit the organic-pollution control efficiency of photo-Fenton ***,through structural design with density functional theory(DFT)calculations,Ce is predicted to enable the construction of coordinatively unsaturated metal centers(CUCs)in Prussian blue analogue(PBA),which can strongly adsorb H_(2)O_(2)and donate sufficient electrons for directly splitting the O-O bond to *** a substitution-co-assembly strategy,binary Ce-Fe PBA is then prepared,which rapidly degrades sulfamethoxazole with the pseudo-first-order kinetic rate constant exceeding reported values by 1-2 orders of ***,the photogenerated electrons reduce Fe(Ⅲ)and Ce(Ⅳ)to promote the metal valence cycle in CUCs and make sulfamethoxazole degradation efficiency only lose 6.04%in 5 ***,by introducing rare earth metals into transition metal-organic frameworks,this work guides the whole process for highly active CUCs from design and construction to mechanism exploration with DFT calculations,enabling ultrafast and stable photo-Fenton catalysis.

关键词： Ce substitution coordinatively unsaturated metal centers photo-Fenton Prussian blue analogue

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Towards Safe Autonomous Driving:Decision Making with Observation‑Robust Reinforcement Learning

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Automotive Innovation 2023年第4期6卷 509-520页

作者： Xiangkun He Chen Lv State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchunChina School of Mechanical and Aerospace Engineering Nanyang Technological University639798 NanyangSingapore

Most real-world situations involve unavoidable measurement noises or perception errors which result in unsafe decision making or even casualty in autonomous *** address these issues and further improve safety,automated driving is required to be capable of handling perception ***,this paper presents an observation-robust reinforcement learning against observational uncertainties to realize safe decision making for autonomous ***,an adversarial agent is trained online to generate optimal adversarial attacks on observations,which attempts to amplify the average variation distance on perturbed *** addition,an observation-robust actor-critic approach is developed to enable the agent to learn the optimal policies and ensure that the changes of the policies perturbed by optimal adversarial attacks remain within a certain ***,the safe decision making scheme is evaluated on a lane change task under complex highway traffic *** results show that the developed approach can ensure autonomous driving performance,as well as the policy robustness against adversarial attacks on observations.

关键词： Autonomous vehicle Robust reinforcement learning Safe decision making Adversarial attack

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Numerical study of a trapezoidal bypass dual throat nozzle

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Chinese Journal of Aeronautics 2023年第3期36卷 42-62页

作者： Shuai HUANG Jinglei XU Kaikai YU Yangsheng WANG Ruifeng PAN Kuangshi CHEN Yuqi ZHANG State Key Laboratory of Mechanics and Control of Aeronautics and Astronautics Structures Nanjing 210016China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Province Key Laboratory of Aerospace Power System Nanjing 210016China

Bypass Dual Throat Nozzle(BDTN)is a novel type of fluidic thrust vectoring *** improve the infrared stealth performance of BDTN,a nozzle based on BDTN is proposed and numerically *** cross-section along the x-axis of the novel nozzle becomes a trapezoid,which is named“BDTN-TRA.”The main numerical simulation results show that BDTN-TRA can produce a thrust vectoring angle when the upper or lower bypass valve is *** angle difference between the two conditions mentioned above is usually approximately 1°-2°.Even if the two bypasses are closed,BDTN-TRA can produce a small thrust vectoring angle at around 3°-5°.When the sidewall angle increases from 60°to 90°,the thrust coefficient and thrust vectoring angle under each work condition usually decrease.A larger aspect ratio indicates better *** the aspect ratio increases over 7.2,the performance of BDTN-TRA is quite close to that of BDTN with rectangular cross-sections at the same aspect *** features will benefit the control and trimming for future aircraft design,especially for the flying wing layout *** but not least,BDTN-TRA has a more extraordinary mixing performance compared with *** distributions of static temperature and axial velocity along the x-axis of BDTN-TRA with sidewall angle of 60°decrease faster than those of *** the total temperature of the inlet equals 1600 K,the static temperature difference between BDTN-TRA with sidewall angles of 60°and 90°is over 360 K at twice the length of the nozzle downstream of the nozzle exit,which is the reflection for excellent infrared stealth for the fighter.

关键词： Bypass dual throat nozzle Infrared stealth performance Mixing performance Trapezoidal cross-sections Thrust vectoring

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On Klein tunneling of low-frequency elastic waves in hexagonal topological plates

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Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1139-1154页

作者： Yuxin YAO Yuansheng MA Fang HONG Kai ZHANG Tingting WANG Haijun PENG Zichen DENG School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical UniversityXi’an710072China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian116024Liaoning ProvinceChina

Incident particles in the Klein tunnel phenomenon in quantum mechanics can pass a very high potential *** the concept of tunneling into the analysis of phononic crystals can broaden the application *** this study,the structure of the unit cell is designed,and the low frequency(<1 k Hz)valley locked waveguide is realized through the creation of a phononic crystal plate with a topological phase transition *** defect immunity of the topological waveguide is verified,that is,the wave can propagate along the original path in the cases of impurities and ***,the tunneling phenomenon is introduced into the topological valley-locked waveguide to analyze the wave propagation,and its potential applications(such as signal separators and logic gates)are further explored by designing phononic crystal *** research has broad application prospects in information processing and vibration control,and potential applications in other directions are also worth exploring.

关键词： topological metamaterial elastic wave Klein tunneling valley-locked waveguide

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Leaching kinetics and permeability of polyethyleneimine added ammonium sulfate on weathered crust elution-deposited rare earth ores

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Journal of Rare Earths 2024年第8期42卷 1610-1619,I0008页

作者： Huifang Yang Aoyang Sha Zhengyan He Chenjie Wu Yuanlai Xu Jingjing Hu Zhigao Xu Ru'an Chi Key Laboratory for Green Chemical Process of Ministry of Education School of Resources&Safety EngineeringWuhan Institute of TechnologyWuhan 430073China Key Laboratory of Resources Conversion and Pollution Control of the State Ethnic Affairs Commission College of Resources and Environmental ScienceSouth-Central MinzuUniversityWuhan430074China

At present,in-situ leaching of weathered crust elution-deposited rare earth ores(WCE-DREOs) encounter with problems such as long leaching cycles,slow infiltration rate and low product *** order to solve the above problems,the conventional leaching agent ammonium sulfate((NH_(4))_(2)SO_(4)) was compounded with polymeric surfactant polyethyleneimine(PEI) to form a composite leaching *** effects of leaching temperature,PEI *** rate and pH on leaching kinetics and permeability of rare earths(RE) and aluminum(AI) in orebody were *** is found that with temperature increasing,the time required to reach leaching equilibrium for both RE and Al is shortened,the apparent activation energies of RE and AI are 14.79 and 13.45 kJ/mol,respectively,and the leaching processes are in accordance with the outer diffusion control,When the concentrations of(NH_(4))_(2)SO_(4) and PEI in the composite leaching agent are 2.0 wt% and 0.4 wt%;the time required to reach leaching equilibrium for RE and AI is about 50% shorter than that using(NH_(4))_(2)SO_(4) alone,and the leaching efficiencies of RE are slightly higher than that of *** increasing the temperature and flow rate of the composite leaching agent can improve the leaching efficiencies of RE and Al,but pH has neglected effects on the leaching efficiencies of *** PEI concentrations below 0,4 wt%, the addition of PEI promotes the leaching of RE and *** column leaching studies of the WCE-DREO,the addition of 0.4 wt% PEI to the traditional leaching agent(NH_(4))_(2)SO_(4) has no impact on the leaching efficiencies of ***,it can significantly increase the infiltration rate of WCE-DREO,shortening the leaching time per 10 mL effluent from about 30 min for(NH_(4))_(2)SO_(4) leaching system to 20 min for the composite leaching *** leaching time is shortened by one-third,and the leaching cost is reduced,which can provide theoretical guidance for the development and commercial implementa

关键词： Polyethyleneimine Kinetics Rare earths Permeability Activation energy

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Optimal Design of the Modular Joint Drive Train for Enhancing Cobot Load Capacity and Dynamic Performance

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Chinese Journal of Mechanical engineering 2024年第3期37卷 26-40页

作者： Peng Li Zhenguo Nie Zihao Li Xinjun Liu Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua UniversityBeijing 100084China

Automation advancements prompts the extensive integration of collaborative robot(cobot)across a range of *** to the commonly used design approach of increasing the payload-to-weight ratio of cobot to enhance load capacity,equal attention should be paid to the dynamic response characteristics of cobot during the design process to make the cobot more *** this paper,a new method for designing the drive train parameters of cobot is ***,based on the analysis of factors influencing the load capacity and dynamic response characteristics,design criteria for both aspects are established for cobot with all optimization design criteria normalized within the design ***,with the cobot in the horizontal pose,the motor design scheme is discretized and it takes the joint motor diameter and gearbox speed ratio as optimization design ***,all the discrete values of the optimization objectives are obtained through the enumeration method and the Pareto front is used to select the optimal solution through multi-objective *** on the cobot design method proposed in this paper,a six-axis cobot is designed and compared with the commercial *** result shows that the load capacity of the designed cobot in this paper reaches 8.4 kg,surpassing the 5 kg load capacity commercial cobot which is used as a *** minimum resonance frequency of the joints is 42.70 Hz.

关键词： Multi-objective optimization Modular joint drive train design Load capacity Dynamic response performance

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