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3D Printing of Periodic Porous Metamaterials for Tunable Electromagnetic Shielding Across Broad Frequencies

Nano-Micro Letters 2024年第12期16卷 533-552页

作者： Qinniu Lv Zilin Peng Haoran Pei Xinxing Zhang Yinghong Chen Huarong Zhang Xu Zhu Shulong Wu State Key Laboratory of Polymer Materials Engineering Polymer Research Institute of Sichuan UniversityNo.24 South Section 1Yihuan RoadChengdu 610065People’s Republic of China Baosheng Technology Innovation corporation limited No.1Suzhong RoadBaoying CountyYangzhou 225800People’s Republic of China

The new-generation electronic components require a balance between electromagnetic interference shielding efficiency and open structure factors such as ventilation and heat *** addition,realizing the tunable shielding of porous shields over a wide range of wavelengths is even more *** this study,the well-prepared thermoplastic polyurethane/carbon nanotubes composites were used to fabricate the novel periodic porous flexible metamaterials using fused deposition modeling 3D ***,the investigation focuses on optimization of pore geometry,size,dislocation configuration and material thickness,thus establishing a clear correlation between structural parameters and shielding *** experimental and simulation results have validated the superior shielding performance of hexagon derived honeycomb structure over other designs,and proposed the failure shielding size(D_(f)≈λ/8-λ/5)and critical inclined angle(θf≈43°-48°),which could be used as new benchmarks for tunable electromagnetic *** addition,the proper regulation of the material thickness could remarkably enhance the maximum shielding capability(85-95 dB)and absorption coefficient A(over 0.83).The final innovative design of the porous shielding box also exhibits good shielding effectiveness across a broad frequency range(over 2.4 GHz),opening up novel pathways for individualized and diversified shielding solutions.

关键词： Polymeric component 3D printing Tunable electromagnetic shielding Periodic porous metamaterials Honeycomb pore structure

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Unraveling engineering disturbance effects on deformation in red-bed mudstone railway cuttings:incorporating crack-facilitated moisture diffusion

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Journal of Mountain Science 2024年第5期21卷 1663-1682页

作者： HUANG Kang DAI Zhangjun YAN Chengzeng YAO Junkai CHI Zecheng CHEN Shanxiong State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China Faculty of Engineering China University of GeosciencesWuhan 430074China International Joint Research Center for Deep Earth Drilling and Resource Development China University of GeosciencesWuhan 430074China china Academy of Railway Sciences corporation limited Beijing 100081China

Red-bed mudstone, prevalent in southwest china, poses a formidable challenge due to its hydrophilic clay minerals, resulting in expansion, deformation, and cracking upon exposure to moisture. This study addresses uplift deformation disasters in high-speed railways by employing a moisture diffusion-deformation-fracture coupling model based on the finite-discrete element method(FDEM). The model integrates the influence of cracks on moisture diffusion. The investigation into various excavation depths reveals a direct correlation between depth and the formation of tensile cracks at the bottom of the railway cutting. These cracks expedite moisture migration, significantly impacting the temporal and spatial evolution of the moisture field. Additionally, crack expansion dominates hygroscopic deformation, with the lateral coordinate of the crack zone determining peak vertical displacement. Furthermore, key factors influencing deformation in railway cuttings, including the swelling factor and initial moisture content at the bottom of the cutting, are explored. The number of tensile and shear cracks increases with greater excavation depth, particularly concerning shear cracks. Higher swelling factors and initial moisture contents result in an increased total number of cracks, predominantly shear cracks. Numerical calculations provide valuable insights, offering a scientific foundation and directional guidance for the precise prevention, control, prediction, and comprehensive treatment of mudstone-related issues in high-speed railways.

关键词： Red-bed mudstone Railway cutting FDEM Moisture diffusion Deformation Crack

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KSKV:Key-Strategy for Key-Value Data Collection with Local Differential Privacy

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 3063-3083页

作者： Dan Zhao Yang You Chuanwen Luo Ting Chen Yang Liu Artificial Intelligence Development Research Center Institute of Scientific and Technical Information of ChinaBeijing100038China Industry Development Department NSFOCUS Inc.BeijingChina School of Information Science and Technology Beijing Forestry UniversityBeijing100083China School of Computer Science and Engineering University of Electronic Science and Technology of ChinaChengdu610054China Institute of Computing Technology China Academy of Railway Sciences Corporation LimitedBeijing10081China

In recent years,the research field of data collection under local differential privacy(LDP)has expanded its focus fromelementary data types to includemore complex structural data,such as set-value and graph ***,our comprehensive review of existing literature reveals that there needs to be more studies that engage with key-value data *** studies would simultaneously collect the frequencies of keys and the mean of values associated with each ***,the allocation of the privacy budget between the frequencies of keys and the means of values for each key does not yield an optimal utility *** the importance of obtaining accurate key frequencies and mean estimations for key-value data collection,this paper presents a novel framework:the Key-Strategy Framework forKey-ValueDataCollection under ***,theKey-StrategyUnary Encoding(KS-UE)strategy is proposed within non-interactive frameworks for the purpose of privacy budget allocation to achieve precise key frequencies;subsequently,the Key-Strategy Generalized Randomized Response(KS-GRR)strategy is introduced for interactive frameworks to enhance the efficiency of collecting frequent keys through group-anditeration *** strategies are adapted for scenarios in which users possess either a single or multiple key-value ***,we demonstrate that the variance of KS-UE is lower than that of existing *** claims are substantiated through extensive experimental evaluation on real-world datasets,confirming the effectiveness and efficiency of the KS-UE and KS-GRR strategies.

关键词： Key-value local differential privacy frequency estimation mean estimation data perturbation

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A Multiscale Reliability-Based Design Optimization Method for Carbon-Fiber-Reinforced Composite Drive Shafts

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1975-1996页

作者： Huile Zhang Shikang Li Yurui Wu Pengpeng Zhi Wei Wang Zhonglai Wang Yangtze Delta Region Institute(Huzhou) University of Electronic Science and Technology of ChinaHuzhou313001China Huzhou Key Laboratory of Green Energy Materials and Battery Cascade Utilization Huzhou CollegeHuzhou313000China SAIC Motor corporation limited Passenger Vehicle Co. Shanghai201804China School ofMechanical and Electrical Engineering University of Electronic Science and Technology of ChinaChengdu611731China

Carbon fiber composites,characterized by their high specific strength and low weight,are becoming increasingly crucial in automotive ***,current research primarily emphasizes layer count and orientation,often neglecting the potential of microstructural design,constraints in the layup process,and performance *** study,therefore,introduces a multiscale reliability-based design optimization method for carbon fiber-reinforced plastic(CFRP)drive ***,parametric modeling of the microscale cell was performed,and its elastic performance parameters were predicted using two homogenization methods,examining the impact of fluctuations in microscale cell parameters on composite material performance.A finite element model of the CFRP drive shaft was then constructed,achieving parameter transfer between microscale and macroscale through Python *** enabled an investigation into the influence of both micro and macro design parameters on the CFRP drive shaft’s *** Multi-Objective Particle Swarm Optimization(MOPSO)algorithm was enhanced for particle generation and updating strategies,facilitating the resolution of multi-objective reliability optimization problems,including composite material layup process *** studies demonstrated that this approach leads to over 30%weight reduction in CFRP drive shafts compared to metallic counterparts while satisfying reliability requirements and offering insights for the lightweight design of other vehicle components.

关键词： Multiscale reliability-based design optimization carbon-fabric-reinforced composite drive shaft

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Fabrication of Bio-inspired Superamphiphobic aluminum Alloy Surface with Oil-triggered Wenzel-Slippery Transition via Femtosecond Laser

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Journal of Bionic Engineering 2024年第3期21卷 1375-1387页

作者： Weijian Liu Feng Guan Fulin Zhang Chenrui Wang Wei Zheng Lu Zhai Zhaohua Lin Chunbao Liu AVIC Shenyang Aircraft corporation Shenyang110000China School of Mechanical and Aerospace Engineering Jilin UniversityChangchun130022China

Surface-tension-confined microfluidic devices are platforms for manipulating 2D droplets based on patterned surfaces with special *** have great potential for various applications,but are still in the early stages of development and face some challenges that need to be *** study,inspired by the Wenzel and slippery transition of rose petal,develops a Patterned Oil-triggered Wenzel-slippery Surface(POWS)to examine the microfluidic devices.A laser-chemical composite method is established to fabricate POWSs,which take rose-petal-like microstructures as wettability pattern and a superamphiphobic surface as the *** prepared POWSs switched between high adhesion superhydrophobic state and the slippery liquid-infused surface state through adding or removing the lubricant *** the high adhesion superhydrophobic state,the droplets can be sticked on the *** the slippery liquid-infused state,the droplet can slide along the wettability pattern as the designed route.A POWS-based droplet reactor is further constructed,on which,the droplets can be remotely controlled to move,mix and react,as *** a POWS,which manipulates droplets with surface tension controlled by the switchable wettability patterns,would be a promising candidate to construct multiple surface-tension-confined microfluidic *** addition,the fabrication technique and design principle proposed here may aid the development of various field related to the bio-inspired surfaces,such as water collection,desalination and high throughput analysis,etc.

关键词： Biomaterials Bio-inspired surface Oil-triggered wenzel-slippery transition Superhydrophobicity Femtosecondlaser

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Revenue management method and critical techniques of railway passenger transport

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Railway Sciences 2024年第5期3卷 636-649页

作者： Xinghua Shan Xiaoyan Lv Jinfei Wu Shuo Zhao Junfeng Zhang Institute of Computing Technologies China Academy of Railway Sciences Corporation LimitedBeijingChina

Purpose–Revenue management(RM)is a significant technique to improve revenue with limited *** the macro environment of dramatically increasing transit capacity and rapid railway transport development in china,it is necessary to involve the theory of RM into the operation and decision of railway passenger ***/methodology/approach–This paper proposes the theory and framework of generalized RM of railway passenger transport(RMRPT),and the thoughts and methods of the main techniques in RMRPT,involving demand forecasting,line planning,inventory control,pricing strategies and information systems,are all studied and *** involved methods and techniques provide a sequential process to help with the decision-making for each stage of *** corresponding techniques are integrated into the information system to support practical businesses in railway passenger ***–The combination of the whole techniques devotes to railway benefit improvement and transit resource utilization and has been applied into the practical operation and organization of railway passenger ***/value–The development of RMRPT would provide theoretical and technical support for the improvement of service quality as well as railway benefits and efficiency.

关键词： Revenue management Railway passenger transport Demand forecasting Line planning Inventory control Pricing strategy

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Integrated Frequency-constrained Scheduling Considering Coordination of Frequency Regulation Capabilities from Multi-source Converters

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 261-274页

作者： Jiaming Li Ying Qiao Zongxiang Lu Wei Ma Xin Cao Rongfu Sun the Department of Electrical Engineering Tsinghua UniversityBeijing 100084China the china Suntien Green Energy limited Company Shijiazhuang 050011China the State Grid Jibei Electric Power Company Beijing 100054China

As the proportion of renewable energy(RE)increases,the inertia and the primary frequency regulation(FR)capability of the power system ***,ensuring frequency security in the scheduling model has become a new technical requirement in power systems with a high share of *** to a shortage of conventional synchronous generators,the frequency support of multi-source converters has become an indispensable part of the system frequency resources,especially variable-speed wind turbine generation(WTG)and battery energy storage(BES).Quantitative expression of the FR capability of multi-source converters is necessary to construct frequency-constrained scheduling ***,the frequency support performance of these converter-interfaced devices is related to their working states,operation modes,and parameters,and the complex coupling of these factors has not been fully exploited in existing *** this study,we propose an integrated frequency-constrained scheduling model considering the coordination of FR capabilities from multi-source *** FR control strategies and variable FR parameters for WTG with or without reserved power are modeled,and multi-target allocation of BES capacity between tracking dispatch instruction and emergency FR is ***,the variable FR capabilities of WTG and BES are embedded into the integrated frequency-constrained scheduling *** nonlinear constraints for frequency security are precisely linearized through an improved iteration-based *** effectiveness of the proposed model is verified in a modified IEEE 24-bus standard *** results suggest that the coordinated participation of BES and WTG in FR can effectively reduce the cost of the scheduling model while meeting frequency security constraints.

关键词： Battery energy storage(BES) wind turbine generation(WTG) frequency regulation(FR) frequency security power system scheduling

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Phase-engineering modulation of Mn-based oxide cathode for constructing super-stable sodium storage

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Journal of Energy Chemistry 2024年第1期88卷 421-427,I0010页

作者： Quanqing Zhao Ruru Wang Ming Gao Bolin Liu Jianfeng Jia Haishun Wu Youqi Zhu Chuanbao Cao Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education School of Chemistry and Materials ScienceShanxi Normal UniversityTaiyuan 030032ShanxiChina Metals and Chemistry Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China Research Center of Materials Science Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green ApplicationsBeijing Institute of TechnologyBeijing 100081China

The Mn-based oxide cathode with enriched crystal phase structure and component diversity can provide the excellent chemistry structure for Na-ion ***,the broad application prospect is obstructed by the sluggish Na^(+)kinetics and the phase transitions upon ***,we establish the thermodynamically stable phase diagram of various Mn-based oxide composites precisely controlled by sodium content tailoring strategy coupling with co-doping and solid-state *** chemical environment of the P2/P'3 and P2/P3 biphasic composites indicate that the charge compensation mechanism stems from the cooperative contribution of anions and *** from the no phase transition to scavenge the structure strain,P2/P'3 electrode can deliver long cycling stability(capacity retention of 73.8%after 1000 cycles at 10 C)and outstanding rate properties(the discharge capacity of 84.08 mA h g^(-1)at 20 C)than P2/P3 ***,the DFT calculation demonstrates that the introducing novel P'3 phase can significantly regulate the Na^(+)reaction dynamics and modify the local electron configuration of *** effective phase engineering can provide a reference for designing other high-performance electrode materials for Na-ion batteries.

关键词： Sodium ion battery Oxide cathode Phase engineering Phase diagram Na~+kinetic

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Implication of community-level ecophysiological parameterization to modelling ecosystem productivity:a case study across nine contrasting forest sites in eastern china

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Journal of Forestry Research 2024年第1期35卷 1-11页

作者： Minzhe Fang Changjin Cheng Nianpeng He Guoxin Si Osbert Jianxin Sun School of Ecology and Nature Conservation Beijing Forestry UniversityBeijing 100083China Research Institute of Energy Saving Environmental ProtectionOccupational Safety and HealthChina Academy of Railway Sciences Corporation LimitedBeijing 100081China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China

Parameterization is a critical step in modelling ecosystem ***,assigning parameter values can be a technical challenge for structurally complex natural plant communities;uncertainties in model simulations often arise from inappropriate model *** we compared five methods for defining community-level specific leaf area(SLA)and leaf C:N across nine contrasting forest sites along the North-South Transect of Eastern china,including biomass-weighted average for the entire plant community(AP_BW)and four simplified selective sampling(biomass-weighted average over five dominant tree species[5DT_BW],basal area weighted average over five dominant tree species[5DT_AW],biomass-weighted average over all tree species[AT_BW]and basal area weighted average over all tree species[AT_AW]).We found that the default values for SLA and leaf C:N embedded in the Biome-BGC v4.2 were higher than the five computational methods produced across the nine sites,with deviations ranging from 28.0 to 73.3%.In addition,there were only slight deviations(<10%)between the whole plant community sampling(AP_BW)predicted NPP and the four simplified selective sampling methods,and no significant difference between the predictions of AT_BW and AP_BW except the Shennongjia *** findings in this study highlights the critical importance of computational strategies for community-level parameterization in ecosystem process modelling,and will support the choice of parameterization methods.

关键词： Biome-BGC Community traits Forest Ecosystems Model parameterization

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Study on physical and mechanical properties of cement asphalt emulsified mortar under track slab

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Railway Sciences 2024年第2期3卷 227-238页

作者： Tao Wang Shaoliang Wu Hengqiong Jia Shanqing Peng Haiyan Li Piyan Shao Zhao Wei Yi Shi china Academy of Railway Sciences corporation limited Metals and Chemistry Research InstituteBeijingChina

Purpose–During the construction process of the china Railway Track System(CRTS)I type filling layer,the nonwoven fabric bags have been used as grouting templates for cement asphalt(CA)emulsified *** porous structure of nonwoven fabrics endowed the templates with breathability and water *** standard requires that the volume expansion rate of CA mortar must be controlled within 1%–3%,which can generate expansion pressure to ensure that the cavities under track slabs are filled ***,the expansion pressure caused some of the water to seep out from the periphery of the filling bag,and it would affect the actual mix proportion of CA *** differences in physical and mechanical properties between the CA mortar under track slabs and the CA mortar formed in the laboratory were studied in this *** relevant results could provide important methods for the research of filling layer materials for CRTS I type and other types of ballastless tracks in ***/methodology/approach–During the inspection of filling layer,the samples of CA mortar from different working conditions and raw materials were taken by uncovering the track slabs and drilling *** physical and mechanical properties of CA mortar under the filling layer of the slab were systematically analyzed by testing the electrical flux,compressive strength and density of mortar in different parts of the filling ***–In this paper,the electric flux,the physical properties and mechanical properties of different parts of CA mortar under the track slab were *** results showed that the density,electric flux and compressive strength of CA mortar were affected by the composition of raw materials for dry powders and different parts of the filling *** addition,the electrical flux of CA mortar gradually decreased within 90 days’*** electrical flux of samples with the thickness of 54 mm was lower than 500 ***,the impermeability and durability of CA

关键词： CA mortar Electric flux Compressive strength Density

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