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Facile fabrication of graphene/g-C_(3)N_(4) for electromagnetic wave absorption

Nano Research 2024年第3期17卷 1687-1698页

作者： Qiang Su Yunfei He Dongdong Liu Daguang Li Long Xia Xiaoxiao Huang Bo Zhong School of Materials Science and Engineering Harbin Institute of Technology WeihaiWeihai 264209China weihai Yunshan Technology co. Ltd.Weihai 264200China State Key Laboratory on Integrated Optoelectronics College of Electronic Science&EngineeringJilin UniversityChangchun 130012China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

With the development of the miniaturization of electronic equipment and lightweight weapon equipment,there are new requirements for electromagnetic wave absorption material(EMWAM).EMWAM has outstanding electromagnetic wave absorption properties and lightweight characteristics beco.e an important direction of *** this study,graphene/g-C_(3)N_(4)(GGCN)EMWAM was first synthesized in situ by simple heat treatment,in which the g-C_(3)N_(4) had a porous structure and dispersed on the surface of *** impedance matching of the GGCN was well adjusted by decreasing the dielectric co.stant and attenuation co.stant due to the g-C_(3)N_(4) semico.ductor property and the graphite-like *** EMW loss mechanism of GGCN was also analyzed by simulating GGCN’s electric field mode distribution and resistance loss power *** analysis result shows that the distribution of g-C_(3)N_(4) among GGCN sheets can produce more polarization effects and relaxation effects by increasing the lamellar ***,the polarization loss of GGCN co.ld be increased successfully by porous g-C_(3)N_(4).Ultimately,the EMW absorption property of GGCN is optimized significantly,and GGCN exhibits excellent EMW absorption *** the thickness is 2 mm,the effective absorption bandwidth(EAB)can reach 4.6 GHz,and when the thickness is 4.5 mm,the minimum reflection loss(RLmin)at 4.56 GHz can reach-34.69 ***,the practical application of EMWAM was studied by radar cross-section(RCS)simulation,showing that GGCN has a good application prospect.

关键词： graphene/g-C_(3)N_(4) impedance matching simulation analysis dielectric loss excellent electromagnetic wave absorption

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Full waveform inversion based on hybrid gradient

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Petroleum Science 2024年第3期21卷 1660-1670页

作者： Chuang Xie Zhi-Liang Qin Jian-Hua Wang Peng Song Heng-Guang Shen Sheng-Qi Yu Ben-Jun Ma Xue-Qin Liu Qingdao Innovation and Development Base Harbin Engineering UniversityQingdao266000ShandongChina Qingdao Innovation and Development Center Harbin Engineering UniversityQingdao266000ShandongChina CNOOC Research Institute co. Ltd.Beijing100028China co.lege of Marine Geoscience Ocean University of ChinaQingdao266100ShandongChina weihai Sunfull Geophysical Exploration Equipment co. Ltd.Weihai264209ShandongChina

The low-wavenumber co.ponents in the gradient of full waveform inversion(FWI)play a vital role in the stability of the ***,when FWI is implemented in some high frequencies and current models are not far away from the real velocity model,an excessive number of low-wavenumber co.ponents in the gradient will also reduce the co.vergence rate and inversion *** solve this problem,this paper firstly derives a formula of scattering angle weighted gradient in FWI,then proposes a hybrid *** hybrid gradient co.bines the co.ventional gradient of FWI with the scattering angle weighted gradient in each inversion frequency band based on an empirical formula derived *** weighted hybrid mode,we can retain some low-wavenumber co.ponents in the initial lowfrequency inversion to ensure the stability of the inversion,and use more high-wavenumber co.ponents in the high-frequency inversion to improve the co.vergence *** results of synthetic data experiment demonstrate that co.pared to the co.ventional FWI,the FWI based on the proposed hybrid gradient can effectively reduce the low-wavenumber co.ponents in the gradient under the premise of ensuring inversion *** also greatly enhances the co.vergence rate and inversion accuracy,especially in the deep part of the *** the field marine seismic data experiment also illustrates that the FWI based on hybrid gradient(HGFWI)has good stability and adaptability.

关键词： Full waveform inversion Hybrid gradient Scattering angle weighted Low-wavenumber co.ponent

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A Novel Model for the Prediction of Liquid Film Thickness Distribution in Pipe Gas-Liquid Flows

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Fluid Dynamics & Materials Processing 2024年第9期20卷 1993-2006页

作者： Yubo Wang Yanan Yu Qiming Wang Anxun Liu School of Thermal Engineering Shandong Jianzhu UniversityJinan250101China Shandong Technology Innovation Center of Carbon Neutrality Shandong Jianzhu UniversityJinan250101China weihai Haihe Technology co. Ltd.Weihai264200China

A model is proposed for liquid film profile prediction in gas-liquid two-phase flow,which is able to provide the film thickness along the circumferential direction and the pressure gradient in the flow direction.A two-fluid model is used to calculate both gas and liquid phases’flow *** seco.dary flow occurring in the gas phase is taken into acco.nt and a sailing boat mechanism is ***,energy co.servation is applied for obtaining the liquid film thickness distribution along the *** film thickness distribution is calculated acco.dingly for different cases;its values are co.pared with other models and available experimental *** a result,the newly proposed model is tested and good performances are *** liquid film thickness distribution in small pipes and inclined pipes is also studied,and regime transition is revealed by liquid film profile *** observed inflection point demonstrates that the liquid film thickness decreases steeply along the circumference,when the circle angle ranges between 30°and 50°for gas-liquid stratified flow with small superficial velocities.

关键词： Film thickness seco.dary flow void fraction pressure gradient regime transition

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Design of bionic water jet thruster with double-chamber driven by electromagnetic force

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International Journal of Mechanical System Dynamics 2024年第3期4卷 292-302页

作者： Chong Cao Yasong Zhang Chengchun Zhang Chun Shen Wen Cheng Zhenjiang Wei Zhengyang Wu Luquan Ren Key Laboratory of Bionic Engineering(Ministry of Education) Jilin UniversityChangchunChina weihai Junming Power Technology co.ltd. WeihaiChina

In response to the limitations of the single-chamber water jet thruster used in underwater vehicles mimicked by natural cephalopods,a novel approach involving a double-chamber water jet thruster has been *** thruster utilizes electromagnetic force to manipulate the diaphragm,thereby altering the volume of the upper and lower chambers to achieve water jet *** investigations were co.ducted to determine the tensile length-force characteristics of the diaphragm made of ***,key parameters of essential propulsion co.ponents,such as solenoid co.ls,electromagnets,and currents,were established based on the tensile length-force curve,and the propulsion capabilities of the system were evaluated through theoretical *** assessments indicate that the system does not produce reverse thrust regardless of whether the co.l moves up or *** experimental results demonstrate that the maximum peak propulsion force generated by the dual-chamber water jet thruster within a 3-s cycle is 0.253N.

关键词： water jet thruster diaphragm electromagnetic force

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A double-layer radiative co.ling co.ting that utilizes the refractive index difference between layers to achieve extremely high solar reflectivity

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Science China Technological Sciences 2024年第10期67卷 3182-3189页

作者： WANG FuQiang LI ChunZhe YANG ZhenNing XIE WeiXin LI Xiang XU ZengHui YAN YuYing CHENG ZiMing School of Energy Science and Engineering Harbin Institute of Technology School of New Energy Harbin Institute of Technology at Weihai China co.struction Eco.Environmental Protection Technology co. Ltd. Faculty of Engineering University of Nottingham

Passive daytime radiative co.ling（PDRC） technology has great potential in reducing co.ling energy co.sumption. In order to further improve the spectral performance of PDRC co.tings, current researchers mostly focus on the selection and size design of functional particles, while ignoring the optical properties enhancement effect caused by the interlayer binder. In this study, based on the principle that the refractive index difference between layers enhanced the backscattering performance of the solar spectrum, we proposed and manufactured a double-layer PDRC co.ting with polyvinylidene difluoride（PVDF） as the filmforming material in the upper layer and polydimethylsiloxane（PDMS） as the film-forming material in the lower layer, both filled with Al2O3and SiO2particles. The double-layer PDRC co.ting exhibited excellent spectral performance that a high solar reflectivity of 98% and an emissivity of 0.95 at the “atmospheric window” band. In co.parison, the solar spectrum reflectivity of the single-layer PDRC co.tings based on PVDF and PDMS of the same thickness was 95% and 94.7%, respectively. Outdoor tests showed that the PDRC co.ting achieved a temperature decrease of up to 7.1℃ under direct sunlight at noon time. In addition, the PDRC co.ting had excellent weather resistance, water resistance, and other basic properties. This article opens up a new idea and provides methodological guidance for the design of double-layer PDRC co.tings.

关键词： double-layer radiative co.ling co.ting spectral modulation interlayer refractive index solar energy radiative transfer

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Multi-scale modeling for prediction of mechanical performance in brazed GH99 thin-walled structure

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Chinese Journal of Aeronautics 2024年第7期37卷 550-563页

作者： Yazhou LIU Shengpeng HU Yanyu SONG Wei FU Xiaoguo SONG Ning GUO Weimin LONG State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Shandong Institute of Shipbuilding Technology Weihai 264209China China Machinery Intelligent Equipment Innovation Research Institute(Ningbo)co. Ltd.Ningbo 315700China

Superalloy thin-walled structures are achieved mainly by brazing,but the deformation process of brazed joints is non-uniform,making it a challenging research *** paper reco.ds a thorough investigation of the effect of brazing parameters on the microstructure of joints and its mechanical properties,which mainly inquires into the deformation and fracture mechanisms in the shearing process of GH99/BNi-5a/GH99 *** macrosco.ic-microsco.ic deformation mechanism of the brazing interface during shearing was studied by Crystal Plasticity(CP)and Molecular Dynamics(MD)on the basis of the optimal brazing *** experimental results show that the brazing interface is mainly formed by(Ni,Cr,co.(s,s)and possesses a shear strength of approximately 546 *** shearing fracture of the brazed joint occurs along the brazing seam,displaying the characteristics of intergranular *** simulations show that dislocations disassociate and transform into fine twinning with increased *** simulated the shear deformation process of the brazed *** multiscale simulation results are co.sistent with the experimental *** mechanical properties of thin-walled materials for brazing are predicted using MD and CP methods.

关键词： Multi-scale modeling Brazing Shear mechanisms Crystal plasticity GH99 superalloy

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Multi-network-region traffic co.perative scheduling in large-scale LEO satellite networks

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Journal of Systems Engineering and Electronics 2024年第4期35卷 829-841页

作者： LI Chengxi WANG Fu YAN Wei CUI Yansong FAN Xiaodong ZHU Guangyu XIE Yanxi YANG Lixin ZHOU Luming ZHAO Ran WANG Ning School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China The 6th Research Institute of China Electronics co.poration Beijing 102209China China Satellite Network Share Operation co. LtdBeijing 100876China weihai Electronic Information Technology co.prehensive Research Center of the Ministry of Industry and Information Technology weihai 264200 China

A low-Earth-orbit(LEO)satellite network can provide full-co.erage access services worldwide and is an essential candidate for future 6G ***,the large variability of the geographic distribution of the Earth’s population leads to an uneven service volume distribution of access ***,the limitations on the resources of satellites are far from being able to serve the traffic in hotspot *** enhance the forwarding capability of satellite networks,we first assess how hotspot areas under different load cases and spatial scales significantly affect the network throughput of an LEO satellite network ***,we propose a multi-region co.perative traffic scheduling *** algorithm migrates low-grade traffic from hotspot areas to co.dspot areas for forwarding,significantly increasing the overall throughput of the satellite network while sacrificing some latency of end-to-end *** algorithm can utilize all the global satellite resources and improve the utilization of network *** model the co.perative multi-region scheduling of large-scale LEO *** on the model,we build a system testbed using OMNET++to co.pare the proposed method with existing *** simulations show that our proposed method can reduce the packet loss probability by 30%and improve the resource utilization ratio by 3.69%.

关键词： low-Earth-orbit(LEO)satellite network satellite co.munication load balance multi-region scheduling latency optimization

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基于实际预压载作业的自升式平台环境载荷图谱绘制新思路

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哈尔滨工程大学学报（英文版） 2024年第1期23卷 209-221页

作者：孙承猛林海花张志刚孙洪源周立师 Naval Architecture and Port Engineering co.lege Shandong Jiao Tong UniversityWeihai 264209China School of Ocean Engineering Harbin Institute of TechnologyWeihai 264209China China Merchants Jinling Shipyard(weihai)co. Ltd.Weihai 264207China

The environmental load chart is an important technical support required for the jack-up drilling platform to facilitate its adaptation to different operating waters and ensure the safety of *** chart is a crucial part of the platform operation *** chart data are closely related to external factors such as water depth,wind,wave,and current co.ditions of the working water,as well as to the structural characteristics of the platform itself and the number of variable *** study examines the platform state under extreme wind,wave,and current co.ditions during *** addition,this study focuses on the difference between the ultimate reaction force of the pile leg during preloading and the reaction force of the pile leg without co.sidering any environmental load before ***,the relationship between the difference and the new reaction force of the pile leg caused by the co.bination of different environmental co.ditions is established to facilitate the co.struction of a new form of environmental load *** newly formed chart is flexible and simple;thus,it can be used to evaluate the environmental adaptability of the platform in the target well location and provides the preloading target demand or variable load limit acco.ding to the given environmental ***,the platform can perform personalized preloading operations,thereby improving its capability to co.e with co.plex geological co.ditions,such as reducing punch-through *** co.dition reduces the load on jacking system devices and increases its service life.

关键词： Jack-up Environmental load chart Preloading Geometrically nonlinear effect Punch through

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FDSC-YOLOv8:Advancements in Automated Crack Identification for Enhanced Safety in Underground Engineering

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co.puter Modeling in Engineering & Sciences 2024年第9期140卷 3035-3049页

作者： Rui Wang Zhihui Liu Hongdi Liu Baozhong Su Chuanyi Ma Key Laboratory of co.puting Power Network and Information Security Ministry of EducationShandong Computer Science Center(National Supercomputer Center in Jinan)Qilu University of Technology(Shandong Academy of Sciences)Jinan250353China School of Qilu Transportation Shandong UniversityJinan250100China Geotechnical and Structural Engineering Center Shandong UniversityJinan250061China Shandong Lairong High-Speed Railway co. Ltd.Weihai264200China Shandong High-Speed Group co. Ltd.Jinan250014China

In underground engineering,the detection of structural cracks on tunnel surfaces stands as a pivotal task in ensuring the health and reliability of tunnel ***,the dim and dusty environment inherent to under-ground engineering poses co.siderable challenges to crack *** paper proposes a crack segmentation algorithm termed as Focused Detection for Subsurface Cracks YOLOv8(FDSC-YOLOv8)specifically designed for underground engineering structural ***,to improve the extraction of multi-layer co.volutional features,the fixed co.volutional module is replaced with a deformable co.volutional ***,the model’s receptive field is enhanced by introducing a multi-branch co.volutional module,improving the extraction of shallow features for small ***,the Dynamic Snake co.volution module is inco.porated to enhance the extraction capability for slender and weak ***,the co.volutional Block Attention Module(CBAM)module is employed to achieve better target *** FDSC-YOLOv8s algorithm’s mAP50 and mAP50-95 reach 96.5%and 66.4%,acco.ding to the testing data.

关键词： Crack segmentation improved YOLOv8 engineering applications feature extraction

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Application of New Type Pre-classification Hydrocyclone with Centrifugal Volute in Grinding Process

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Journal of Chemistry and Chemical Engineering 2013年第12期7卷 1213-1218页

作者： Xueqi Cui Shuli Wang Jun Suo Lei Wang Jimin Zheng weihai haiwang cyclone co. ltd Weihai 264203 China

Hydrocyclone is widely used in closed-circuit grinding process. However, in the first classification operation of co.rse particles with high pulp density, the shortco.ings of traditional cyclone are that the grinding cycle load is much high, the apex of cyclone is easily to be blocked and classification efficiency is less. Specifically, the problems of traditional cyclone used in grinding process are as follows：（1） Mill utilization factor is low and its handling capacity is small; （2） co.rse particles mixing in cyclone overflow affects the following separation process and fine particles mixing in underflow causes over-grinding, which affects the total reco.ery rate of valuable minerals; （3） High grinding cycle load leads to large amount of high-density slurry pumping, which causes high energy co.sumption and severe wear of cyclones, pipelines and pumps. The applications of new type pre-classification hydrocyclone with centrifugal volute in the first classification process of iron mine mill are introduced in the paper. Pulp particles fed in the centrifugal volute are arranged in advance, so that co.rse particles can be far away from the overflow pipe, which can reduce the short circuit current to avoid co.rse particles entering overflow and improve classification efficiency and accuracy of cyclone. The strong points of the new cyclone in the co.rse classification operation are as follows：（1） Finer overflow and less fine particles mixing in underflow improves classification efficiency more than 10%; （2） Lower ball mill load cycle improves ball capacity more than 10%; （3） Grinding energy co.sumption reduces by more than 20% and cyclone feed pump reduces energy co.sumption by more than 12%. In short, new type pre-classification cyclone with centrifugal volute solves the problems of fine particles mixing in underflow, high grinding cycle load and less classification efficiency in the co.rse classification operation. Therefore, it has broad application prospects in ferr

关键词： Centrifugal volute hydrocyclone pre-classification.

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