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Science China(Technological Sciences) 2022年第7期65卷 1613-1633页

作者： XIE ZhongLiang jiao Jian YANG Kang HE tao Department of Engineering Mechanics Northwestern Polytechnical UniversityXi'an 710072China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China School of Mechanical-Electric Engineering Xidian UniversityXi'an 710071China Wuhan Second Ship Design and Research Institute Wuhan 430205China

The paper studies the anti-eccentric load margin of a novel structure bearing lubricated by low viscosity medium. The lubrication dynamic model considering journal inclination angle is established. The effects of different speeds, loads, and tilted angles on the interface attributes of the bearing under typical working conditions are studied. The results show that the special structure bearing has self-stability margin of anti-tilted and anti-eccentric load. Particularly under different speed conditions, analyses show that the eccentric load has little influence on the static/dynamic characteristics of the bearing. Under the same conditions, the stability margin of the bearing is higher than that of traditional bearings. The research provides a theoretical basis for the application of such kinds of special structure bearings.

关键词： water-lubricated bearing tilted angle anti-eccentric load margin lubrication performance

Achieving ultra-broadband electromagnetic absorption of Ag regulated hollow Ag/CuO@CuS through balancing conduction loss and impedance matching

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Journal of Materials Science & Technology 2023年第13期144卷 81-92页

作者： Siyuan Zhang Jinlei tao Rui Sun Shipeng Hu Jian jiao Northwestern Polytechnical University Xi’an 710072China

Excellent impedance matching and high conduction loss are important factors for the preparation of high-performance electromagnetic wave(EMW)absorbing materials,but these two properties are of-ten contradictory.In this work,three absorbers with unique hollow structures,H-Ag/CuO@CuS,H-O-Ag/CuO@CuS,and H-P-Ag/CuO@CuS,are designed and synthesized by adopting hollow CuO@CuS with double shell as carrier and silver nitrate as the structural regulator.The more voids coming from hol-low structures,window-opened structures,and stacked pores improve the impedance matching of these absorbers,and the introduction of elemental Ag effectively regulates the conduction loss.Therefore,a balance between impedance matching and conduction loss is achieved to improve the reflection loss(RL)value and broadens the absorbing band of the absorbers.In comparison to H-Ag/CuO@CuS and H-O-Ag/CuO@CuS(hollow structure with open window)in which elemental Ag is uniformly dispersed in the CuO layer,H-P-Ag/CuO@CuS exhibits more excellent EMW absorption performance due to more voids and an optimized conductive network arising from Ag/CuO pieces distributed between the hol-low Ag/CuO@CuS particles and Ag distributed in the CuS layer.When the thickness is 2.3 mm,H-P-Ag/CuO@CuS provides an ultra-wide electromagnetic absorption band of 8.56 GHz(9.44-18 GHz),in which the RL<-10 dB and the minimum reflection loss of-41 dB.

关键词： Elemental sliver Impedance matching Conduction loss Electromagnetic wave absorption

Achieving efficient N_(2)electrochemical reduction by stabilizing the N2H*intermediate with the frustrated Lewis pairs

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Journal of Energy Chemistry 2022年第3期31卷 628-634,I0017页

作者： Zhe Chen Jingxiang Zhao Yan jiao tao Wang Lichang Yin Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016LiaoningChina Center of Artificial Photosynthesis for Solar Fuels School of ScienceWestlake UniversityHangzhou 310024ZhejiangChina College of Chemistry and Chemical Engineering and Key Laboratory of Photonic and Electronic Bandgap MaterialsMinistry of EducationHarbin Normal UniversityHarbin 150025HeilongjiangChina Centre for Materials in Energy and Catalysis(CMEC) School of Chemical Engineering and Advanced MaterialsThe University of AdelaideAdelaideSA5005Australia Department of Physics and Electronic Information Huaibei Normal UniversityHuaibei 235000AnhuiChina

Electrocatalytic nitrogen reduction reaction(eNRR)with sustainable energy under ambient conditions represents an attractive approach to producing ammonia,but the design of the-state-of-the-art electrocatalyst with high efficiency and selectivity still faces formidable challenges.In contrast to traditional eNRR catalyst design strategies focusing on N≡N triple bond activation,we herein theoretically proposed an alternative strategy to improve eNRR performance via stabilizing the N_(2)H^(*)intermediate using catalysts with the frustrated Lewis pairs(FLPs),i.e.,transition metal(TM)atoms and boron(B)atom co-doped 2D black phosphorus(TM-B@BP).Our density functional theory(DFT)results reveal that the TM atom donates electrons to the adsorbed N_(2)molecule,while B atom provides empty orbital to stabilize the adsorption of N_(2)H^(*)intermediate.This framework successfully identifies five promising candidates(i.e.,Ti-B@BP,V-B@BP,Cr-B@BP,Mn-B@BP and Fe-B@BP)with low theoretical limiting potentials(−0.60,−0.41,−0.45,−0.43 and−0.50 V,respectively)and high selectivity for eNRR.We believe that the intermediate stabilization strategy introduced in current work offers a new opportunity to achieve accelerated and cost-effective ammonia synthesis with electrocatalysis.

关键词： Nitrogen reduction Electrocatalysis Intermediate stabilization strategy Density functional theory

Design of FeSiBPCu soft magnetic alloys with good amorphous forming ability and ultra-wide crystallization window

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Journal of Materials Science & Technology 2023年第16期147卷 124-131页

作者： Xingdu Fan tao Zhang Weiming Yang Junhua Luan Zengbao jiao Hui Li Jiangsu Key Laboratory for Advanced Metallic Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China Institute of Massive Amorphous Metal Science China University of Mining and TechnologyXuzhou 221116China Center for Advanced Structural Materials Department of Mechanical and Biomedical EngineeringCollege of Science and EngineeringCity University of Hong KongKowloonHong KongChina Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong KongChina School of Materials Science and Engineering Shanghai UniversityShanghai 200444China

The Fe_(81.3)Si_(4)B_(13–x)PxCu_(1.7) soft magnetic alloys with high Cu and proper P elements addition were synthesized with the aim of ensuring the amorphous forming ability(AFA)while expanding the crystallization window(CW).It is found that the atomic ratio of P/Cu of∼3 is advantageous for AFA whereas a small amount of P addition promotes the precipitation ofα-Fe grains and excessive P addition induces surface crystallization behavior of the present alloys.High Cu concentration can expand the annealing temperature(Ta)window whereas proper P addition effectively expands the annealing time(ta)window.The Fe_(81.3)Si_(4)B_(13-x)PxCu_(1.7) soft magnetic alloy was successfully synthesized with a large Ta window of up to 130°C and ta window of 90 min,which is a breakthrough for nanocrystalline alloys with high saturation magnetization.Microstructure analysis reveals that the ultra-wide CW is related to the unique nucleation mechanism,that is,theα-Fe grains are precipitated attaching to the Cu or CuP clusters and enveloping the Cu clusters,resulting in the high number density ofα-Fe nanocrystals.The ultra-wide CW promises the potential material in flexibly choosing the annealing process according to the performance.

关键词： Nanocrystalline alloys Amorphous forming ability Crystallization window Soft magnetic properties

Optimal design of a large dual-polarization microstrip reflectarray with China-coverage patterns for satellite communications

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Frontiers of Information Technology & Electronic Engineering 2020年第1期21卷 159-173页

作者： Gang ZHAO Yong-chang jiao Guan-tao CHEN National Key Laboratory of Antennas and Microwave Technology Xidian UniversityXi’an 710071China

A large dual-polarization microstrip reflectarray with China-coverage patterns in two operating bands is designed.To sufficiently compensate for the spatial phase delay differences in two operating bands separately,a three-layer rectangular patch element is addressed,which is suitable for the large dual-polarization reflectarray.Due to the complexly shaped areas and high gain requirements,there are more than 25000 elements in the reflectarray,making it difficult to design,due to more than 150000 optimization variables.First,the discrete fast Fourier transform(DFFT)and the inverse DFFT are used to establish a one-to-one relationship between the aperture distribution and the far field,which lays a foundation for optimizing the shaped-beam reflectarray.The intersection approach,based on the alternating projection,is used to obtain the desired reflection phases of all the elements at some sample frequencies,and a new method for producing a suitable initial solution is proposed to avoid undesired local minima.To validate the design method,a dual-polarization shaped-beam reflectarray with 7569 elements is fabricated and measured.The measurement results are in reasonable agreement with the simulation ones.Then,for the large broadband reflectarray with the minimum differential spatial phase delays in the operating band,an approach for determining the optimal position of the feed is discussed.To simultaneously find optimal dimensions of each element in two orthogonal directions,we establish a new optimization model,which is solved by the regular polyhedron method.Finally,a dual-band dual-polarization microstrip reflectarray with 25305 elements is designed to cover the continent of China.Simulation results show that patterns of the reflectarray meet the China-coverage requirements in two operating bands,and that the proposed optimization method for designing large reflectarrays with complexly shaped patterns is reliable and efficient.

关键词： Reflectarray Dual-polarization Shaped beam Phase-only synthesis

Two-Stage Lesion Detection Approach Based on Dimension-Decomposition and 3D Context

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Tsinghua Science and Technology 2022年第1期27卷 103-113页

作者： Jiacheng jiao Haiwei Pan Chunling Chen tao Jin Yang Dong Jingyi Chen the College of Computer Science and Technology Harbin Engineering UniversityHarbin 150001China the School of Software Tsinghua UniversityBeijng 100084China

Lesion detection in Computed Tomography(CT) images is a challenging task in the field of computer-aided diagnosis.An important issue is to locate the area of lesion accurately.As a branch of Convolutional Neural Networks(CNNs),3D Context-Enhanced(3DCE) frameworks are designed to detect lesions on CT scans.The False Positives(FPs) detected in 3DCE frameworks are usually caused by inaccurate region proposals,which slow down the inference time.To solve the above problems,a new method is proposed,a dimension-decomposition region proposal network is integrated into 3DCE framework to improve the location accuracy in lesion detection.Without the restriction of "anchors" on ratios and scales,anchors are decomposed to independent "anchor strings".Anchor segments are dynamically combined in accordance with probability,and anchor strings with different lengths dynamically compose bounding boxes.Experiments show that the accurate region proposals generated by our model promote the sensitivity of FPs and spend less inference time compared with the current methods.

关键词： lesion detection Computed Tomography(CT) dimension-decomposition 3D context computer-aided diagnosis

Providing Guaranteed Network Performance across Tenants:Advances,Challenges and Opportunities

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China Communications 2021年第2期18卷 152-174页

作者： Chengyuan Huang jiao Zhang tao Huang Yunjie Liu State Key Laboratory of Networking and Switching Technology BUPTBeijingChina Purple Mountain Laboratories NanjingChina

The varied network performance in the cloud hurts application performance.This increases the tenant’s cost and becomes the key hindrance to cloud adoption.It is because virtual machines(VMs)belonging to one tenant can reside in multiple physical servers and communication interference across tenants occasionally occurs when encountering network congestion.In order to prevent such unpredictability,it is critical for cloud providers to offer the guaranteed network performance at tenant level.Such a critical issue has drawn increasing attention in both academia and industry.Many elaborate mechanisms are proposed to provide guaranteed network performance,such as guaranteed bandwidth or bounded message delay across tenants.However,due to the intrinsic complexities and limited capabilities of commodity hardware,the deployment of these mechanisms still faces great challenges in current cloud datacenters.Moreover,with the rapid development of new technologies,there are new opportunities to improve the performance of existing works,but these possibilities are not under full discussion yet.Therefore,in this paper,we survey the latest development of the network performance guarantee approaches and summarize them based on their features.Then,we explore and discuss the possibilities of using emerging technologies as knobs to upgrade the performance or overcome the inherent shortcomings of existing advances.We hope this article will help readers quickly Received:Apr.07,2020 Revised:Oct.23,2020 Editor:Haifeng Zheng understand the causes of the problems and serve as a guide to motivate researchers to develop innovative algorithms and frameworks.

关键词： cloud computing network performance guaranteed bandwidth guaranteed delay

Comparative Analysis of the Generalized Omega Equation and Generalized Vertical Motion Equation

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Advances in Atmospheric Sciences 2023年第5期40卷 856-873页

作者： Baofeng jiao Lingkun RAN Na LI Ren CAI tao QU Yushu ZHOU Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China Urumqi City Bureau of Meteorology Urumqi 830002China

Research on vertical motion in mesoscale systems is an extraordinarily challenging effort.Allowing for fewer assumptions,a new form of generalized vertical motion equation and a generalized Omega equation are derived in the Cartesian coordinate system(nonhydrostatic equilibrium)and the isobaric coordinate system(hydrostatic equilibrium),respectively.The terms on the right-hand side of the equations,which comprise the Q vector,are composed of three factors:dynamic,thermodynamic,and mass.A heavy rain event that occurred from 18 to 19 July 2021 in southern Xinjiang was selected to analyze the characteristics of the diagnostic variable in the generalized vertical motion equation(Qz)and the diagnostic variable in the generalized Omega equation(Qp)using high-resolution model data.The results show that the horizontal distribution of the Qz-vector divergence at 5.5 km is roughly similar to the distribution of the Qp-vector divergence at 500 hPa,and that both relate well to the composite radar reflectivity,vertical motion,and hourly accumulated precipitation.The Qz-vector divergence is more effective in indicating weak precipitation.In vertical cross sections,regions with alternating positive and negative large values that match the precipitation are mainly concentrated in the middle levels for both forms of Q vectors.The temporal evolutions of vertically integrated Qz-vector divergence and Qp-vector divergence are generally similar.Both perform better than the classical quasigeostrophic Q vector and nongeostrophic Q vector in indicating the development of the precipitation system.

关键词： generalized Omega equation generalized vertical motion equation Q vector heavy rain

Compositionally complex coherent precipitation-strengthened high-entropy alloys:a critical review

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Rare Metals 2022年第6期41卷 2002-2015页

作者： Jin-Xiong Hou Bo-Xuan Cao Bo Xiao Zeng-Bao jiao tao Yang Department of Materials Science and Engineering City University of Hong KongHong Kong 999077China Hong Kong Institute for Advanced Study City University of Hong KongHong Kong 999077China Department of Mechanical Engineering.The Hong Kong Polytechnic University Hong Kong 999077China

The coherent precipitation-strengthened high-entropy alloys(CPS-HEAs)as a new type of structural materials are expected to possess many unique mechanical properties,such as the outstanding strength-ductility com-bination at cryogenic and room temperatures.Apart from this,most of their strengths can even be well retained at elevated temperatures.The compositionally complex matrix and nanoprecipitation phases,as well as the coherent interfaces between them,can potentially bring novel merits of these CPS-HEAs,including sluggish dif-fusion,excellent thermal stability,and controlled magnetic properties.Note that the ductile coherent L1_(2)-nanoparticles can improve the strength of alloys without too much reduction of plasticity,while the coherent B2-nanoparticles strengthened HEAs display completely brittle failure upon tensile test at room temperature.An overview of the alloy design,microstructure evolution,oxidation resistance,mechanical and magnetic properties of CPS-HEAs are briefly discussed here.The advantages of multicomponent coherent precipitation-strengthened HEAs as well as the limitations in this field are also summarized.In addition,this review also points out the future research directions and prospects.

关键词： High-entropy alloys Coherent precipitation strengthening Multicomponent intermetallic Mechanical properties Magnetic properties

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Phyton-International Journal of Experimental Botany 2022年第9期91卷 2005-2016页

作者： Yanqing Wu jiao Liu Yuhan Tang Daqiu Zhao Jun tao Joint International Research Laboratory of Agriculture and Agri-Product Safety The Ministry of Education of ChinaInstitutes of Agricultural Science and Technology DevelopmentYangzhou UniversityYangzhou225009China Jiangsu Key Laboratory of Crop Genetics and Physiology College of Horticulture and Plant ProtectionYangzhou UniversityYangzhou225009China

The ornamental and commercial values of herbaceous peony(Paeonia lactiflora Pall.)are directly related to its flower pattern.However,the molecular mechanisms underlying the type formation of P.lactiflora flowers have not been studied in great detail.Previous studies identified,using integrated multipleomics analysis,revealed that APETALA2(AP2)is an important candidate gene that modulates type formation of P.lactiflora flowers.To further reveal the expression mechanism of AP2 in P.lactiflora petals,we examined the profile of AP2 expression in the inner and outer petals of‘ZiFengyu’at various developmental stages using qRT-PCR and BSP+Miseq methylation analysis.Based on our data,the AP2 levels in the outer petals were obviously increased,relative to the inner petals.In addition,the S3 levels at the bloom stage were significantly higher than at the flower-bud stage S1,thereby promoting bloom stage S2,while declining stage S4.Using chromosome walking,the 2000 bp of the 5′-end upstream promoter region was achieved.This region harbored a CpG island(−665∼−872 bp),with multiple essential transcription factor binding sites(TFBS)such as NF-kappa B,GATA-1,Sp1,and C/EBP.Methylation sequencing revealed 7 methylated CpG sites in the CpG island region of the AP2 promoter,thereinto,the methylation ratio of the CpG-3 site in the inner petals was significantly higher than in the outer petals.Correlation analysis revealed a negative association between the level of methylation(CpG-3,CpG-6),and AP2 mRNA expression.CpG-3 was located on the Sp1 transcription factor binding site.Thus,we speculated that the CpG-3 methylation may inhibit transcription factor Sp1 binding to the gene promoter,thereby regulating AP2 expression.Herein,we examined the role of AP2 in the determination of flower patterns in P.lactiflora.Our conclusion will provide theoretical guidance for the molecular breeding of the flower pattern in P.lactiflora.

关键词： Herbaceous peony APETALA2(AP2) developmental expression DNA methylation