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Layered Structural PBAT Composite Foams for Efficient Electromagnetic Interference Shielding

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Nano-Micro Letters 2024年第2期16卷 273-286页

作者： Jianming Yang Hu Wang Yali zhang hexin zhang Junwei Gu School of Chemistry and Chemical Engineering Anhui University of TechnologyMa’anshanAnhui 243032People’s Republic of China Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710072ShaanxiPeople’s Republic of China School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003JiangsuPeople’s Republic of China

The utilization of eco-friendly,lightweight,high-efficiency and high-absorbing electromagnetic interference(EMI)shielding composites is imperative in light of the worldwide promotion of sustainable *** this work,magnetic poly(butyleneadipate-coterephthalate)(PBAT)microspheres were firstly synthesized via phase separation method,then PBAT composite foams with layered structure was constructed through the supercritical carbon dioxide foaming and scraping *** merits of integrating ferroferric oxideloaded multi-walled carbon nanotubes(Fe3O4@MWCNTs)nanoparticles,a microcellular framework,and a highly conductive silver layer have been judiciously orchestrated within this distinctive layered *** are consumed throughout the process of“absorption-reflection-reabsorption”as much as possible,which greatly declines the secondary radiation *** biodegradable PBAT composite foams achieved an EMI shielding effectiveness of up to 68 dB and an absorptivity of 77%,and authenticated favorable stabilization after the tape adhesion experiment.

关键词： Electromagnetic interference shielding Layered structure Supercritical carbon dioxide foaming Poly(butyleneadipateco-terephthalate) Microcellular

Morphology and Properties of PP In-reactor Alloys Prepared with a MgCl2/TiCl4/Diisobutyl Phthalate/Phosphate Tris-methylphenyl Ester Catalyst System

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Chemical Research in Chinese Universities 2018年第1期34卷 145-150页

作者： zhang Chunyu DONG Bo zhang hexin HU Yanming zhang Xuequan Key Laboratory of Synthetic Rubber of Chinese Academy of Sciences Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 P. R. China

A series of polypropylene（PP）/poly（ethylene-co-propylene） in-reactor alloys with different ethylene contents was prepared through a two-stage polymerization process using a MgCl2/TiCl4/diisobutyl phthalate/phosphate tris-methylphenyl ester catalyst system. The ethylene content, particle shape, fractured surface, and glass-transition temperature（Tg） of the obtained PP in-reactor alloys were characterized by means of nuclear magnetic resonance, scanning electron microscopy（SEM）, and dynamic mechamcal analysis（DMA）. The ethylene content of the PP alloys increased from 2.34% to 26.69% when the propylene/ethylene feed ratio was increased from 66/34 to 54/46（molar ratio）. Morevoer, the increment in ethylene content increased the notched Izod impact strength of the resulting PP alloys. The impact strength of the PP alloy with an ethylene content of 26.69% was 55.8 kJ/m^2, which is 12.7 times that of isotactic polypropylene. The results of DMA and SEM analysis reveal that ethylene-propylene random copolymer（EPR） in the PP alloy has a low Tg of ca. -50℃ and a high interface compatibility with the PP matrix. The excellent impact performance of the PP alloy can be attributed to the uniform dispersal of EPR in the alloy particles and PP matrix.

关键词： Polypropylene m-reactor alloy Phosphate Ziegler-Natta catalyst Ethylene-propylene random copolymer Toughening mechanism

Localization and mapping algorithm based on Lidar-IMU-Camera fusion

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Journal of Intelligent and Connected Vehicles 2024年第2期7卷 97-107页

作者： Yibing Zhao Yuhe Liang Zhenqiang Ma Lie Guo hexin zhang School of Mechanical Engineering Dalian University of TechnologyDalian 116024China Department of the Built Environment Technology University of EindhovenEindhoven 5600MBthe Netherlands

Positioning and mapping technology is a difficult and hot topic in autonomous driving environment sensing *** a complex traffic environment,the signal of the Global Navigation Satellite System(GNSS)will be blocked,leading to inaccurate vehicle *** ensure the security of automatic electric campus vehicles,this study is based on the Lightweight and Ground-Optimized Lidar Odometry and Mapping on Variable Terrain(LEGO-LOAM)algorithm with a monocular vision system *** algorithm framework based on Lidar-IMU-Camera(Lidar means light detection and ranging)fusion was proposed.A lightweight monocular vision odometer model was used,and the LEGO-LOAM system was employed to initialize monocular *** visual odometer information was taken as the initial value of the laser *** the back-end opti9mization phase error state,the Kalman filtering fusion algorithm was employed to fuse the visual odometer and LEGO-LOAM system for *** visual word bag model was applied to perform loopback *** the test results into account,the laser radar loopback detection was further optimized,reducing the accumulated positioning *** real car experiment results showed that our algorithm could improve the mapping quality and positioning accuracy in the campus *** Lidar-IMU-Camera algorithm framework was verified on the Hong Kong city dataset *** with the LEGO-LOAM algorithm,the results show that the proposed algorithm can effectively reduce map drift,improve map resolution,and output more accurate driving trajectory information.

关键词： Lightweight and Ground-Optimized Lidar Odometry and Mapping on Variable Terrain(LEGO-LOAM) monocular vision system error state Kalman filter odometer

Constitutive Modeling and Dynamic Recrystallization Mechanisms of an Ultralow-carbon Microalloyed Steel During Hot Compression Tests

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Journal of Wuhan University of Technology(Materials Science) 2020年第5期35卷 946-957页

作者： LI Ning HUANG Yao HAN Renheng BAO Ziming ZHU Yanqing zhang hexin ZHAO Chengzhi Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationCollege of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China

The hot deformation behavior of an ultralow-carbon microalloyed steel was investigated using an MMS-200 thermal simulation test machine in a temperature range of 1073-1373 K and strain rate range of 0.01-10 *** results show that the flow stress decreases with increasing deformation temperature or decreasing strain *** strain-compensated constitutive model based on the Arrhenius equation for this steel was established using the true stress-strain data obtained from a hot compression ***,a new constitutive model based on the Z-parameter was proposed for this *** predictive ability of two constitutive models was compared with statistical *** results indicate the new constitutive model based on the Z-parameter can more accurately predict the flow stress of an ultralow-carbon microalloyed steel during hot *** dynamic recrystallization(DRX)nucleation mechanism at different deformation temperatures was observed and analyzed by transmission electron microscopy(TEM),and strain-induced grain boundary migration was observed at 1373 K/0.01 s^-1.

关键词： ultra-low carbon microalloyed steel hot deformation behavior constitutive modeling dynamic recrystallization

Preparation of graphene/MgCl_2-supported Ti-based Ziegler-Natta catalysts by the coagglomeration method and their application in ethylene polymerization

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Chinese Journal of Catalysis 2017年第1期38卷 131-137页

作者： hexin zhang Yanming Hu Xuequan zhang Department of Polymer Science and Engineering Kyungpook National University Daegu 702‐701 Korea Key Laboratory of Synthetic Rubber Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130012 Jilin China

We report a facile coagglomeration method for preparing graphene (G)/MgCl2‐supported Ti‐based Ziegler‐Natta catalysts. The effects of graphene feed ratio on catalyst morphology and ethylene polymerization behavior were examined. The synthesized catalyst exhibited very high activity for ethylene polymerization. The resultant polyethylene (PE)/G nanocomposites showed a layered morphology, and the graphene fillers were well dispersed in the PE matrix. In addition, the thermal stability and mechanical properties of PE were significantly enhanced with the introduction of a very small amount of G fillers (0.05 wt%). This work provides a facile approach to the production o fhigh‐performance PE.

关键词： Ziegler‐Natta catalyst Polyethylene Graphene Nanocomposite In‐situ polymerization

A YOLOv8-CE-based real-time traffic sign detection and identification method for autonomous vehicles

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Digital Transportation and Safety

Digital Transportation and Safety 2024年第3期3卷 82-91页

作者： Yuechen Luo Yusheng Ci hexin zhang Lina Wu School of Transportation Science and Engineering Harbin Institute of TechnologyHarbinChina School of Future Technology Harbin Institute of TechnologyHarbinChina School of Automobile and Traffic Engineering Heilongjiang Institute of TechnologyHarbinChina

Traffic sign detection in real scenarios is challenging due to their complexity and small size,often preventing existing deep learning models from achieving both high accuracy and real-time *** improved YOLOv8 model for traffic sign detection is ***,by adding Coordinate Attention(CA)to the Backbone,the model gains location information,improving detection ***,we also introduce EIoU to the localization function to address the ambiguity in aspect ratio descriptions by calculating the width-height difference based on ***,Focal Loss is incorporated to balance sample difficulty,enhancing regression ***,the model,YOLOv8-CE(YOLOv8-Coordinate Attention-EIoU),is tested on the Jetson Nano,achieving real-time street scene detection and outperforming the Raspberry Pi *** results show that YOLOv8-CE excels in various complex scenarios,improving mAP by 2.8%over the original *** model size and computational effort remain similar,with the Jetson Nano achieving an inference time of 96 ms,significantly faster than the Raspberry Pi 4B.

关键词： YOLOv8-CE-based Real-time Traffic Signs Detection

Study on Ground Fissures and Land Subsidence Induced by Seepage Deformation in Xi'an

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Meteorological and Environmental Research 2018年第6期9卷 53-61页

作者： zhang Jianjun zhang hexin zhang Maosheng Tao Hong Dong Yin Xu Chaomei Key Laboratory of Mine Geological Hazards Mechanism and Control Xi'an 710054China Shaanxi Institute of Geo-Environment Monitoring Xi'an 710054China China University of Geosciences(Beijing) Beijing 100083China Xi'an Center of Geological Survey China Geological SurveyXi'an 710054China

There are lots of theories about the causation of ground fissures in Xi’an,such as the tectonics theory,the excessive groundwater exploitation theory and the compositive theory. Based on the construction of the geologic environment monitoring network in Guanzhong urban agglomeration,the latest survey of ground fissures and land subsidence in Yuhuazhai in Xi’an shows that the extensive piping and quicksand in self-supply wells is a factor to induce ground fissures and land subsidence. It is suggested that the seepage deformation caused by high hydraulic gradient leads to sand gushing and changes some aquifers into the composite aquifer,which is the main factor to induce ground fissures and land subsidence. The development characteristics of ground fissures and land subsidence caused by seepage deformation were summarized. The results will supply new schemes and methods for the causation of land subsidence and ground fissures in Xi’an and lay out a clear road map of measures to control land subsidence and ground fissures.

关键词： Seepage deformation Land subsidence Ground fissures Xi'an Composite aquifer

Dirichlet空间上一类积分算子的约化子空间

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数学物理学报（A辑） 2021年第3期41卷 595-602页

作者：张核心河北师范大学数学科学学院石家庄050024

刻画了n移位算子加带特定权的Volterra算子T_(1)在Dirichlet空间上的相似性,利用算子理论技巧证明了T_(1)在Dirichlet空间上的作用和乘法算子M_(p)在空间S(D)上的作用相似,进一步证明了当p(z)=z^(n)时相应的算子T_(2)有2^(n)个约化子空间.

关键词： Dirichlet空间 Volterra算子 n移位算子约化子空间

TiO_2/SiO_2复合气凝胶的制备与传热特性

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哈尔滨工程大学学报 2012年第3期33卷 389-393页

作者：张贺新方双全哈尔滨工程大学材料科学与化学工程学院黑龙江哈尔滨150001

针对SiO2气凝胶红外遮光性能差的问题,以纳米二氧化钛作为掺杂剂,以正硅酸乙酯(TEOS)为原料,采用溶胶-凝胶工艺和非超临界干燥方法制备了不同TiO2掺杂量的纳米孔改性SiO2气凝胶复合材料,研究了pH值和乙醇含量对凝胶时间的影响,并采用SEM... 详细信息

针对SiO2气凝胶红外遮光性能差的问题,以纳米二氧化钛作为掺杂剂,以正硅酸乙酯(TEOS)为原料,采用溶胶-凝胶工艺和非超临界干燥方法制备了不同TiO2掺杂量的纳米孔改性SiO2气凝胶复合材料,研究了pH值和乙醇含量对凝胶时间的影响,并采用SEM、TEM和BET方法分别对凝胶的表面形貌和孔结构进行了分析表征.结果表明,当pH为6时,乙醇/TEOS为8:1(摩尔比)时,可得到掺杂均匀、完整的TiO2/SiO2凝胶;热处理后的复合气凝胶具有网状纳米孔结构;当掺杂量小于5%时,干凝胶平均孔径为20～50 nm,比表面积均大于1 000 m2/g.通过红外透过率及消光性能比较,TiO2掺杂SiO2干凝胶复合材料的红外光屏蔽功能较纯SiO2气凝胶提高了50%.

关键词： TiO2/SiO2气凝胶非超临界干燥光屏蔽传热特性