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Hydrolytic dehydrogenation of ammonia borane catalyzed by poly(amidoamine) dendrimers-modified reduced graphene oxide nanosheets supported Ag_(0.3)Co_(0.7) nanoparticles

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Journal of Materials Science & Technology 2018年第12期34卷 2350-2358页

作者： Dandan Ke Jin Wang Hongming Zhang Yuan Li Lu Zhang Xin Zhao Shumin Han hebei Key Laboratory of Applied Chemistry School of Environmental and Chemical EngineeringYanshan University State Key Laboratory of Metastable Materials Science and Technology Yanshan University School of Materials and Metallurgy Inner Mongolia University of Science and Technology

Poly(amidoamine) dendrimers-modified reduced graphene oxide nanosheets(PAMAM/rGO) composite was selected as a carrier of heterogeneous Ag0.3Co0.7nanoparticles in order to obtain an excellent catalyst for ammonia borane(AB) hydrolysis. During the synthetic processes, GO could easily assembled with PAMAM by the electrostatic and hydrogen-bonding interactions. Structural characterization revealed that Ag0.3Co0.7bimetallic nanoparticles with uniform size distribution of 5 nm are well dispersed on PAMAM/rGO composite architecture. Ag0.3Co0.7@PAMAM/rGO was found to be a highly active and reusable catalyst in hydrogen generation from the hydrolysis of AB with a turnover frequency value(TOF) of 19.79 molH2min-1molM-1at 25.0±0.1℃ and retained 75.4% of their initial activity with a complete release of hydrogen in five runs. The relatively high TOF value and low apparent activation energy(34.21 kJ mol-1) make these Ag0.3Co0.7@PAMAM/rGO NPs as a high-efficient catalyst for catalytic dehydrogenation of AB facilitating the development of practically applicable energy storage materials.

关键词： Ammonia borane Reduced graphene oxide Ammonia borane Ag_(0.3)Co_(0.7) bimetallic nanoparticles Hydrolytic dehydrogenation

Instability of roll nonlinear system with structural clearance in rolling process

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Journal of Iron and Steel Research International 2023年第1期30卷 112-125页

作者： Jin-xing Cui Yan Peng Jin Wang National Engineering Research Center for Equipment and Technology of Cold Rolled Strip School of Mechanical EngineeringYanshan UniversityQinhuangdao 066004HebeiChina

The vibration instability of the nonlinear dynamic system of the rolls considering the structural clearance was theoretically investigated,which is caused by the roll assembly accuracy deviation in the hot rolling ***,the dynamic rolling force model was established based on the Wekbrod model under the influence of the roll grinding deviation and the stability of the deformation ***,the horizontal and vertical direction coupling dynamic model of the work roll was established considering the structural clearance between the roll and mill ***,the nonlinear dynamic equation was solved by the Runge-Kutta *** simulation results show that the dynamic system presents the nonlinear vibration characteristics,which shows that the instability of the system is a slowly varying response process with the characteristics of self-excited vibration and forced ***,the comparison results show the consistency between the simulation and the test.

关键词： Roll grinding accuracy Dynamic rolling force Structural clearance Collision Rolling mill instability

MPFracNet:A Deep Learning Algorithm for Metacarpophalangeal Fracture Detection with Varied Difficulties

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Computers, Materials & Continua 2023年第4期75卷 999-1015页

作者： Geng Qin Ping Luo Kaiyuan Li Yufeng Sun Shiwei Wang Xiaoting Li Shuang Liu Linyan Xue College of Quality and Technical Supervision Hebei UniversityBaoding071002China hebei Technology innovation Center for Lightweight of New Energy Vehicle Power System Baoding071002China National&Local Joint Engineering Research Center of Metrology Instrument and System Hebei UniversityBaoding071002China

Due to small size and high occult,metacarpophalangeal fracturediagnosis displays a low accuracy in terms of fracture detection and locationin X-ray *** efficiently detect metacarpophalangeal fractures on Xrayimages as the second opinion for radiologists,we proposed a novel onestageneural network namedMPFracNet based ***,a deformable bottleneck block(DBB)was integrated into the bottleneckto better adapt to the geometric variation of the ***,an integrated feature fusion module(IFFM)was employed to obtain morein-depth semantic and shallow detail ***,Focal Loss andBalanced L1 Loss were introduced to respectively attenuate the imbalancebetween positive and negative classes and the imbalance between detectionand location *** assessed the proposed model on the test set andachieved an AP of 80.4%for the metacarpophalangeal fracture *** estimate the detection performance for fractures with different difficulties,the proposed model was tested on the subsets of metacarpal,phalangeal andtiny fracture test sets and achieved APs of 82.7%,78.5%and 74.9%,*** proposed framework has state-of-the-art performance for detectingmetacarpophalangeal fractures,which has a strong potential application valuein practical clinical environments.

关键词： Deep learning small object detection metacarpophalangeal fractures computer-aided diagnosis(CAD)

The electrochemical characteristics of AB_(4)-type rare earth-Mg-Ni-based superlattice structure hydrogen storage alloys for nickel metal hydride battery

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Journal of Magnesium and Alloys 2021年第6期9卷 2039-2048页

作者： Wenfeng Wang Xiaoxue Liu Lu Zhang Shuang Zhang Wei Guo Yumeng Zhao Hongming zhang Yuan Li Shumin Han State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004PR China School of Environmental and Chemical Engineering Yanshan UniversityQinhuangdao 066004PR China

Rare earth-Mg-Ni-based alloys with superlattice structures are new generation negative electrode materials for the nickel metal hydride *** them,the novel AB_(4)-type superlattice structure alloy is supposed to have superior cycling stability and rate *** its preparation is hindered by the crucial requirement of temperature and the special composition which is close to the other superlattice ***,we prepare rare earth-Mg-Ni-based alloy and study the phase transformation of alloys to make clear the formation of AB_(4)-type *** is found Pr_(5)Co_(19)-type phase is converted from Ce_(5)Co_(19)-type phase and shows good stability at higher temperature compared to the Ce_(5)Co_(19)-type phase in the range of 930-970℃.Afterwards,with further 5℃increasing,AB_(4)-type superlattice structure forms at a temperature of 975℃by consuming Pr_(5)Co_(19)-type *** contrast with A_(5)B_(19)-type alloy,AB_(4)-type alloy has superior rate capability owing to the dominant advantages of charge transfer and hydrogen ***,AB_(4)-type alloy shows long lifespan whose capacity retention rates are 89.2%at the 100;cycle and 82.8%at the 200;cycle,***_(4)-type alloy delivers 1.53 wt.%hydrogen storage capacity at room temperature and exhibits higher plateau pressure than Pr_(5)Co_(19)-type *** work provides novel AB_(4)-type alloy with preferable electrochemical performance as negative electrode material to inspire the development of nickel metal hydride batteries.

关键词： Nickel metal hydride batteries Hydrogen storage alloys AB_(4)-type superlattice structure Electrochemical performance Kinetics properties

Enhanced electrochemical properties of LaFeO_3 with Ni modification for MH–Ni batteries

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International Journal of Minerals,Metallurgy and Materials 2018年第10期25卷 1201-1207页

作者： Zhen-tao Dong Yuan Li Kai-liang Ren Shu-qin Yang Yu-meng Zhao Yong-jie Yuan Lu Zhang Shu-min Han State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Environmental and Chemical Engineering Yanshan University

In this work,we synthesized LaFeO_3–xwt%Ni(x=0,5,10,15)composites via a solid-state reaction method by adding Ni to the reactants,La_2O_3 and Fe_2O_***-emission scanning electron microscopy(FE-SEM)and energy-dispersive X-ray spectroscopy(EDS)results revealed that Ni powders evenly dispersed among the LaFeO_3 particles and apparently reduced their aggregation,which imparted the composites with a loose ***,the Ni formed a conductive network,thus improving the conductivity of the *** maximum discharge capacity of the LaFeO_3 electrodes remarkably increased from 266.8 mAh·g^(–1)(x=0)to 339.7 mAh·g^(–1)(x=10).In particular,the high-rate dischargeability of the LaFeO_3–10wt%Ni electrode at a discharge current density of 1500 mA·g^(-1) reached 54.6%,which was approximately 1.5 times higher than that of the pure LaFeO_*** a Ni-modified loose structure not only increased the charge transfer rate on the surface of the LaFeO_3 particles but also enhanced the hydrogen diffusion rate in the bulk LaFeO_3.

关键词： LaFeO3 nickel modification electrochemical performances MH–Ni batteries

Absorption enhancement of ultrathin crystalline silicon solar cells with frequency upconversion nanosphere arrays

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Communications in Theoretical Physics 2020年第1期72卷 118-123页

作者： Chenbo Wang Shuai Zhao Fei Bian Daxue Du Chunsheng Wang Zhaopeng Xu School of Information Science and Engineering the Key Laboratory for Special Fiber and Fiber Sensor of Hebei ProvinceYanshan UniversityQinhuangdao 066004China School of Environment and Chemical Engineering Yanshan UniversityQinhuangdao 066004China College of Vehicles and Energy Yanshan UniversityQinhuangdao 066004China

A design of ultrathin crystalline silicon solar cells patterned withα-NaEr0.2Y0.8F4 upconversion nanosphere(NSs)arrays on the surface was *** light trapping performance ofα-NaEr0.2Y0.8F4 NSs with different ratios of sphere diameter to sphere pitch was systematically studied by COMSOL *** influence of different NS diameters and ratio to the average optical absorption of ultrathin crystalline silicon solar cell was calculated,as well as the short circuit current *** results show that the average optical absorption of solar cells with 2.33μm silicon covered byα-NaEr0.2Y0.8F4 NSs of 100 nm in diameter and 5.2 in ratio has improved by 8.5%compared to planar silicon solar cells with the same thickness of *** light trapping performance of different thicknesses of silicon solar cells with the optimized configuration of NSs was also *** results indicate that our structure enhances the light *** presented model will be the basis for further simulations concerning frequency upconversion ofα-NaEr0.2Y0.8F4 materials.

关键词： solar cells nanostructure NaYF4:Er3+ light trapping

Effects of the hierarchical pyrolysis polyaniline on reversible hydrogen storage of LiBH4

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Progress in Natural Science:Materials International 2018年第4期28卷 529-533页

作者： Zhenmin Ding Yufei Ma DANDan Peng Lu Zhang Yumeng Zhao Yuan Li Shumin Han State Key Laboratory of Metastable Materials Science and Technology Yanshan University hebei Key Laboratory of Applied Chemistry School of Environmental and Chemical Engineering Yanshan University Lucky Healthcare Company Limited

In this work,LiBH;–20 wt%PP composite was prepared by ball-milling with as-synthesized hierarchical pyrolysis polyaniline（PP）and LiBH;,and the hydrogen sorption performance as well as catalytic mechanism of the composite was *** is found that the onset desorption temperature of the composite decreases to 75°C,almost 235°C lower than that of the milled LiBH;.Moreover,the composite could release 4.1 wt%H;and rehydrogenate a total of 4.4 wt%H;when the temperature raiseds up to 400°C,showing an outstanding reversibility,which even 3.9 wt%H;can be kept after five *** scanning electron microscopy（SEM）observation and X-ray diffraction（XRD）analysis,we found that the PP surface forms some nanoholes after hydrogenation-dehydrogenation cycles,which leads to the confinement of some LiBH;in the PP nanoporous structure,therefore,the hydrogen sorption kinetics and reversibility are significantly *** addition,we also found the oxygenic groups of the PP can react with LiBH;forming LiBO;and Li;BO;,where the containing Li–B–O bonds loaded in the porous structure of the PP catalyze the hydrogenation reaction of LiBH;.

关键词： LiBH4 Pyrolysis polyaniline Complex hydride Hydrogen storage materials Reversible de/hydrogenation

Hot deformation behavior and the processing map of Zr–1.0Be alloy in single α phase

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Progress in Natural Science:Materials International 2015年第5期25卷 496-502页

作者： Zhihao Feng Xiaojun Jiang Yunkai Zhou Chaoqun Xia Xinyu Zhang Mingzhen Ma Riping Liu State Key Laboratory of Metastable Materials Science and Technology Yanshan University

The hot deformation behavior,hot workability and dynamic recrystallization evolution of Zr-1.0（wt%） Be alloy in single a phase were investigated by conducting hot compression *** strain rates ranging from 10-3s-1to 10° s-1and testing temperatures varying from 650 ℃to 850℃ were *** stress was found to increase with increasing strain rate and decrease with the increment of the deformation temperature.A constitutive equation of flow behavior was established to describe the dependence of flow stress on strain rate and deformation *** activation energy for deformation of Zr-1.0Be alloy was determined to be Q= 301 kJ/*** processing map of Zr-1.0Be alloy was constructed at strain rates ranging from 10-3s-1to 10° s-1and deformation temperatures varying from 650 ℃ to 850 ℃ at the true strain of 0.7.A processing map was used to identify the best domains of thermal processing,including a domain at a temperature of 650 ℃ and strain rate of 10-3s-1as well as another domain at deformation temperatures ranging from 800 ℃ to 850 ℃ and strain rates varying from 10-3s--1to *** analysis of *** alloy showed that the flow instability and kink were very obvious at low temperatures and high strain *** high temperatures and low strain rates,the dynamic recrystallization became the main softening mechanism during hot working.

关键词： Zr alloy Hot deformation Constitutive equation Microstructure Dynamic recrystallization

Multi-Classification of Polyps in Colonoscopy Images Based on an Improved Deep Convolutional Neural Network

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Computers, Materials & Continua 2023年第6期75卷 5837-5852页

作者： Shuang Liu Xiao Liu Shilong Chang Yufeng Sun Kaiyuan Li Ya Hou Shiwei Wang Jie Meng Qingliang Zhao Sibei Wu Kun Yang Linyan Xue College of Quality and Technical Supervision Hebei UniversityBaoding071002China hebei Technology innovation Center for Lightweight of New Energy Vehicle Power System Baoding071002China National&Local Joint Engineering Research Center of Metrology Instrument and System Hebei UniversityBaoding071002China College of Electronic Information Engineering Hebei UniversityBaoding071002China Department of Orthopedics Affiliated Hospital of Hebei UniversityBaoding071002China State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics Center for Molecular Imaging and Translational MedicineDepartment of Laboratory MedicineSchool of Public HealthXiamen UniversityXiamen361102China

Achieving accurate classification of colorectal polyps during colonoscopy can avoid unnecessary endoscopic biopsy or *** study aimed to develop a deep learning model that can automatically classify colorectal polyps histologically on white-light and narrow-band imaging(NBI)colonoscopy images based on World Health Organization(WHO)and Workgroup serrAted polypS and Polyposis(WASP)classification criteria for colorectal ***-light and NBI colonoscopy images of colorectal polyps exhibiting pathological results were firstly collected and classified into four categories:conventional adenoma,hyperplastic polyp,sessile serrated adenoma/polyp(SSAP)and normal,among which conventional adenoma could be further divided into three sub-categories of tubular adenoma,villous adenoma and villioustublar adenoma,subsequently the images were re-classified into six *** this paper,we proposed a novel convolutional neural network termed Polyp-DedNet for the four-and six-category classification tasks of colorectal *** on the existing classification network ResNet50,Polyp-DedNet adopted dilated convolution to retain more high-dimensional spatial information and an Efficient Channel Attention(ECA)module to improve the classification performance *** eliminate gridding artifacts caused by dilated convolutions,traditional convolutional layers were used instead of the max pooling layer,and two convolutional layers with progressively decreasing dilation were added at the end of the *** to the inevitable imbalance of medical image data,a regularization method DropBlock and a Class-Balanced(CB)Loss were performed to prevent network ***,the 5-fold cross-validation was adopted to estimate the performance of Polyp-DedNet for the multi-classification task of colorectal *** accuracies of the proposed Polyp-DedNet for the four-and six-category classifications of colorectal polyps were 89.91%±0.92%and 85.13%±1.10%,respectively.

关键词： Colorectal polyps four-and six-category classifications convolutional neural network dilated residual network