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Mass-spring model for elastic wave propagation in multilayered van der Waals metamaterials

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Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1107-1118页

作者： Yabin jing Lifeng WANG Yuqiang gao State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

Multilayered van der Waals(vdW)materials have attracted increasing interest because of the manipulability of their superior optical,electrical,thermal,and mechanical properties.A mass-spring model(MSM)for elastic wave propagation in multilayered vdW metamaterials is reported in this *** dynamics(MD)simulations are adopted to simulate the propagation of elastic waves in multilayered vdW *** results show that the graphene/MoS_(2)metamaterials have an elastic wave bandgap in the terahertz *** MSM for the multilayered vdW metamaterials is proposed,and the numerical simulation results show that this model can well describe the dispersion and transmission characteristics of the multilayered vdW *** MSM can predict elastic wave transmission characteristics in multilayered vdW metamaterials stacked with different two-dimensional(2D)*** results presented in this paper offer theoretical help for the vibration reduction of multilayered vdW semiconductors.

关键词： multilayered van der Waals(vd W)metamaterial molecular dynamics(MD) mass-spring model(MSM) dispersion relation transmission characteristic

Advances in bio-inspired electrocatalysts for clean energy future

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Nano Research 2024年第2期17卷 515-533页

作者： jing-Wen Duan Mu Min-Rui gao Division of Nanomaterials&Chemistry Hefei National Laboratory for Physical Sciences at the MicroscaleDepartment of ChemistryUniversity of Science and Technology of ChinaHefei 230026China

Electrocatalysis can enable efficient energy storage and conversion and thus is an effective way to achieve carbon *** unique structure and function of organisms can offer many ideas for the design of electrocatalysts,which has become one of the most promising research ***,the understanding of the mechanism of bio-inspired electrocatalysis has become clearer,which has promoted the design of bio-inspired catalysts and catalytic *** bio-inspired catalysts(enzyme-like catalysts,layered porous catalysts,superhydrophobic/superhydrophilic surfaces,and so on)have been developed to enable efficient electrocatalytic ***,we discuss the key advances in the field of bio-inspired electrocatalysts progressed in recent ***,the role of bio-inspiration in increasing the intrinsic activity and number of active sites of catalysts is ***,the structure and mechanism of layered porous catalytic systems that mimic biological transport systems are comprehensively ***,the design of three-phase interfaces from micro-nanoscale to atomic scale is highlighted,including the wettability of the electrode surface and the transport system near the *** conclude the review by identifying challenges in bio-inspired electrocatalysts and providing insights into future prospects for the exciting research field.

关键词： bio-inspired electrocatalysts active sites layered porous structure three-phase interface

Recorded recurrent deep reinforcement learning guidance laws for intercepting endoatmospheric maneuvering missiles

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Defence Technology（防务技术） 2024年第1期31卷 457-470页

作者： Xiaoqi Qiu Peng Lai Changsheng gao Wuxing jing Department of Aerospace Engineering Harbin Institute of TechnologyHarbin150001China Shanghai Electro-Mechanical Engineering Institute Shanghai Academy of Spaceflight TechnologyShanghai201100China

This work proposes a recorded recurrent twin delayed deep deterministic(RRTD3)policy gradient algorithm to solve the challenge of constructing guidance laws for intercepting endoatmospheric maneuvering missiles with uncertainties and observation *** attack-defense engagement scenario is modeled as a partially observable Markov decision process(POMDP).Given the benefits of recurrent neural networks(RNNs)in processing sequence information,an RNN layer is incorporated into the agent’s policy network to alleviate the bottleneck of traditional deep reinforcement learning methods while dealing with *** measurements from the interceptor’s seeker during each guidance cycle are combined into one sequence as the input to the policy network since the detection frequency of an interceptor is usually higher than its guidance *** training,the hidden states of the RNN layer in the policy network are recorded to overcome the partially observable problem that this RNN layer causes inside the *** training curves show that the proposed RRTD3 successfully enhances data efficiency,training speed,and training *** test results confirm the advantages of the RRTD3-based guidance laws over some conventional guidance laws.

关键词： Endoatmospheric interception Missile guidance Reinforcement learning Markov decision process Recurrent neural networks

Exhaust hood performance and its improvement technologies in industrial buildings:A literatu rereview

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Building Simulation 2024年第1期17卷 23-40页

作者： jing Zhang Jian Wang Jun gao Weimin Zhang Architectural Engineering Institute Jinhua PolytechnicJinhua 321017China Institute of HVAC Engineering Schoolof Mechanical EngineeringTongji UniversityShanghai 200092China Tongji Architectural Design(Group)Co .LtdShanghai 200092China

The pollutant control performance of exhaust hoods plays a crucial role in the indoor air quality and energy consumption of ventilation systems in industrial *** better understand the impact of local ventilation on the industrial indoor environment,this paper presents a literature review of exhaust hood performance and its improvement *** create an index for evaluating the performance of exhaust hoods,the capture velocity,capture efficiency,flow ratio of pollutant emissions and exhaust airflow and energy consumption are first introduced.A number of factors affecting exhaust hood performance are assessed such as hood type,hood opening size,exhaust rate,installation distance,pollution source emission and environmental *** to structural improvement methods,the use of active airflow is a more effective way to improve the exhaust hood *** most commonly used methods for determining the exhaust rate are the controlled speed method and the flow ratio *** use of an exhaust hood with an appropriate exhaust rate and jet parameters(for an active air-assisted hood)can effectively improve the pollutant control performance and reduce the energy consumption that would be wasted on the redundant exhaust *** more information focused on exhaust hood performance,this work suggests more effective strategies for improving indoor air quality and reducing energy consumption in industrial buildings.

关键词： industrial ventilation exhaust hood capture efficiency exhaust rate performance improvement

Room temperature self-healing liquid metals:capabilities,applications and challenges

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International Journal of Smart and Nano Materials 2024年第3期15卷 469-501页

作者： Chen Hua Jianye gao jing Liu Key Lab of Cryogenic Science and Technology Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijingChina School of Future Technology University of Chinese Academy of SciencesBeijingChina School of Biomedical Engineering Tsinghua UniversityBeijingChina

Self-healing materials span diverse application fields,including flexible electronics,soft robotics,and energy ***,conventional self-healing materials pose a challenge in achiev-ing the delicate balance between flexibility and electrical ***,they also suffer from prolonged healing times,incomplete healing,and high manufacturing *** metals possess excellent self-healing capabilities owing to their unique combination of fluidic and metallic properties,high surface tension,and reversible solid-liquid phase change at room temperature,offering an intriguing material option for addressing the challenges associated with flexibility and elec-trical *** this review article,we comprehensively examine the domain of self-healing liquid metals from the standpoint of typical mechanisms underlying self-healing pro-cesses,as well as practical strategies employed for achieving such ***,we explore representative applications that showcase the potential of these materials while aiming to provide a valuable reference for advancing and enhancing the field of self-healing *** pro-spect along this direction is made.

关键词： Self-healing Liquid metal Smart materials

Core shift limitation in investment casting process of hollow turbine blade

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Chinese Journal of Aeronautics 2024年第8期37卷 513-526页

作者： Kang CUI Lin jing Ruisong JIANG Longnv YU Xiao gao Automation and Software Engineering Shanxi UniversityTaiyuan 030006China Key Laboratory of High Performance Manufacturing for Aero Engine Ministry of Industry and Information TechnologySchool of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China School of Mechanical Engineering Sichuan UniversityChengdu 610065China

The deviation in wall thickness caused by core shift during the investment casting process significantly impacts the strength and service life of hollow turbine *** address this issue,a core shift limitation method is developed in this ***,a shift model is established based on computational fluid dynamics and motion simulation to predict the movement of the ceramic core in investment casting ***,utilizing this model,an optimization method for fixturing layout inside the refractory ceramic shell is devised for the ceramic *** casting experiment demonstrates that by utilizing the optimized fixture layout,not only can core shift during the investment casting pouring process be effectively controlled,but also the maximum wall thickness error of the blade can be reduced by 42.02%.In addition,the core shift prediction is also validated,with a prediction error of less than 26.9%.

关键词： Hollow turbine blade Wall thickness Ceramic core Shift prediction Fixturing layout optimization

Research on the IL-Bagging-DHKELM Short-Term Wind Power Prediction Algorithm Based on Error AP Clustering Analysis

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Computers, Materials & Continua 2024年第6期79卷 5017-5030页

作者： jing gao Mingxuan Ji Hongjiang Wang Zhongxiao Du School of Electric Power Shenyang Institute of EngineeringShenyang100083China

With the continuous advancement of China’s“peak carbon dioxide emissions and Carbon Neutrality”process,the proportion of wind power is *** the current research,aiming at the problem that the forecasting model is outdated due to the continuous updating of wind power data,a short-term wind power forecasting algorithm based on Incremental Learning-Bagging Deep Hybrid Kernel Extreme Learning Machine(IL-Bagging-DHKELM)error affinity propagation cluster analysis is *** algorithm effectively combines deep hybrid kernel extreme learning machine(DHKELM)with incremental learning(IL).Firstly,an initial wind power prediction model is trained using the Bagging-DHKELM ***,Euclidean morphological distance affinity propagation AP clustering algorithm is used to cluster and analyze the prediction error of wind power obtained from the initial training ***,the correlation between wind power prediction errors and Numerical Weather Prediction(NWP)data is introduced as incremental updates to the initial wind power prediction *** the incremental learning process,multiple error performance indicators are used to measure the overall model performance,thereby enabling incremental updates of wind power *** examples show the method proposed in this article reduces the root mean square error of the initial model by 1.9 percentage points,indicating that this method can be better adapted to the current scenario of the continuous increase in wind power penetration *** accuracy and precision of wind power generation prediction are effectively improved through the method.

关键词： Short-term wind power prediction deep hybrid kernel extreme learning machine incremental learning error clustering

Effect of two-step solid solution on microstructure andδphase precipitation of Inconel 718 alloy

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2199-2207页

作者： Enyu Liu Qingshuang Ma Xintong Li Aoxue gao jing Bai Liming Yu Qiuzhi gao Huijun Li School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao 066004China School of Materials Science&Engineering Tianjin UniversityTianjin 300354China School of Mechanical Materials and Mechatronic EngineeringUniversity of WollongongWollongongNSW 2522Australia

Inconel 718 is the most popular nickel-based superalloy and is extensively used in aerospace,automotive,and energy indus-tries owing to its extraordinary thermomechanical *** effects of different two-step solid solution treatments on microstructure andδphase precipitation of Inconel 718 alloy were studied,and the transformation mechanism fromγ″metastable phase toδphase was *** precipitates were statistically analyzed by X-ray *** results show that theδphase content firstly increased,and then decreased with the temperature of the second-step solid *** changes in microstructure andδphase were studied by scanning electron microscopy and transmission electron *** intragranularδphase formed in Inconel 718 alloy at the second-[100]_(δ)[011]γ step solid solution temperature of 925℃,and its orientation relationship withγmatrix was determined as//and(010)_(δ)//(111)γ.Furthermore,the Vickers hardness of different heat treatment samples was measured,and the sample treated by second-step solid solution at 1010℃ reached the maximum hardness of HV 446.84.

关键词： Inconel 718 alloy two-step solid solution treatment δphase γ″-δtransformation

Study on thermal cycling ageing resistance of performances of polypropylene/elastomer/boron nitride nanocomposites for high voltage direct current cable insulation

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High Voltage 2024年第3期9卷 556-565页

作者： jing Li Yu gao Zheng Song Baixin Liu Chenyi Guo Yu Chen Junguo gao Boxue Du School of Electrical and Information Engineering Tianjin UniversityTianjinChina State Grid Tianjin Chengxi Electric Power Supply Branch TianjinChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbinChina

The influences of thermal cycling ageing on structures and insulation performances of polypropylene(PP)/elastomer/boron nitride(BN)nanocomposites are *** Melt blending method was used to prepare the nanocomposites,in which propylene-based elastomer(PBE)or ethylene-octene copolymer elastomer(EOC)was contained for ***,the samples were treated using a thermal cycling process with a temperature range from-30 to 150℃,and the number of thermal cycles was set from 0 to *** electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry and X-ray diffraction measurements were taken to facilitate the comprehension of structural ***,measurements were taken to assess the trap distribution and direct current(DC)breakdown strength of the *** obtained results revealed that following thermal cycling ageing,the morphology and crystallinity of PP/PBE/BN remained almost *** contrast,PP/EOC/BN exhibited substantial microstructural damage accompanied by a significant reduction in *** the number of thermal cycles increased,the trap level and DC breakdown strength of PP/PBE/BN were maintained at high levels,while those of PP/EOC/BN initially remained stable but then experienced a sharp *** is sug-gested that the addition of BN nanoparticles enhances the thermal cycling ageing resis-tance of the PP/PBE blend,whereas it weakens this resistance of the PP/EOC blend.

关键词： cycling resistance thermal