检索结果-南通市图书馆

International Journal of Minerals,Metallurgy and materials 2024年第10期31卷 2233-2243页

作者： Guonan ma Shize Zhu Dong Wang Peng Xue Bolüxiao Zongyi ma Shi-changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Centre of Excellence for Advanced materials Dongguan 523808China

A high-zinc composite,12vol%SiC/Al-13.3 Zn-3.27 Mg-1.07Cu(wt%),with an ultra-high-strength of 781 MPa was success-fully fabricated through a powder metallurgy method,followed by an extrusion *** effects of solid-solution and aging heat treat-ments on the microstructure and mechanical properties of the composite were extensively *** with a single-stage sol-id-solution treatment,a two-stage solid-solution treatment(470℃/1 h+480℃/1 h)exhibited a more effective solid-solution strengthen-ing owing to the higher degree of solid-solution and a more uniform *** to the aging hardness curves of the com-posite,the optimized aging parameter(100℃/22 h)was *** the aging temperature and time resulted in finer and more uniform nanoscale precipitates but only yielded a marginal increase in tensile *** fractography analysis revealed that intergranu-lar cracking and interface debonding were the main fracture mechanisms in the ultra-high-strength SiC/Al-Zn-Mg-Cu *** regions,such as the SiC/Al interface containing numerous compounds and the precipitate-free zones at the high-angle grain boundaries,were identified as significant factors limiting the strength enhancement of the *** compounds,including MgO,MgZn2,and Cu5Zn8,reduced the interfacial bonding strength,leading to interfacial debonding.

关键词： metal matrix composites heat treatment interfacial reaction mechanical properties fracture mechanism

Experimental Study on Engineering Behavior of Solidified Soil for Scour Repair and Protection

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第4期38卷 625-635页

作者： WU xiao-ni LI Ru-yu SHU jian TANG Chao CHEN Jin-jian WANG Hui-li jianG Hai-li WANG xiao State Key Laboratory of Ocean Engineering Department of Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Road and Bridge Group Co. Ltd.Shanghai 200433China Shanghai Engineering Research Center of Urban Infrastructure Renewal Shanghai 200032China jiangsu Kunze Technology Co. Ltd.Nanjing 210000China

A new scour countermeasure using solidified slurry for offshore foundation has been proposed *** solidified slurry is pumped to seabed area around foundation for scour protection or pumped into the developed scour holes for scour repair as the fluidized material solidifies *** the pumping operation and solidification,the engineering behaviors of solidified slurry require to be considered synthetically for the reliable application in scour repair and protection of ocean engineering such as the pumpability related flow value,flow diffusion behavior related rheological property,anti-scour performance related retention rate in solidification and bearing capacity related strength property after *** this study,a series of laboratory tests are conducted to investigate the effects of mix proportion(initial water content and binder content)on the flow value,rheological properties,density,retention rate of solidified slurry and unconfined compressive strength(UCS).The results reveal that the flow value increases with the water content and decreases with the binder *** the solidified slurry exhibits Bingham plastic behavior when the shear rate is larger than 5 s^(-1).The Bingham model has been employed to fit the rheology test results,and empirical formulas for obtaining the density,yield stress and viscosity are established,providing scientific support for the numerical assessment of flow and diffusion of solidified *** rate of solidified slurry decreases with the water flow velocity and flow value,which means the pumpability of solidified slurry is contrary to anti-scour *** unconfined compressive strength after solidification reduces as the water content increases and binder content decreases.A design and application procedure of solidified soil for scour repair and protection is also proposed for engineering reference.

关键词： scour repair and protection solidified soil pumpability strength flow properties anti-scour performance

Core-shell heterostructure engineering of CoP nanowires coupled NiFe LDH nanosheets for highly efficient water/seawater oxidation

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第8期35卷 549-553页

作者： Guo-Hong Gao Run-Ze Zhao Ya-Jun Wang xiao ma Yan Li jian Zhang Ji-Sen Li School of Chemistry Chemical Engineering and MaterialsJining UniversityQufu 273155China Institute of Physical Education Jining UniversityQufu 273155China Key Laboratory of Advanced Energy materials Chemistry(Ministry of Education) Nankai UniversityTianjin 300071China

Searching for efficient nonprecious metal-based catalysts toward oxygen evolution reaction(OER)are of significance for seawater ***,a core-shell-structured hybrid of cobalt phosphide nanowires@NiFe layered double hydroxide nanosheets grown on conductive nickel foam(CoP@NiFe LDH/NF)is prepared by a feasible approach at low *** charming structure can provide numerous phosphide/hydroxide heterogenous interfaces,expose abundant active sites,and boost elec-tron/mass transfer,synergistically enhancing catalytic OER *** employed as an electrocatalyst toward the OER,the resultant CoP@NiFe LDH/NF only requires a small overpotential of 287 mV to pro-vide 300 ma/cm^(2)current density as well as long-time durability in 1.0 mol/L KOH *** regula-tion of electronic states and surface reconstruction synergistically contribute to highly efficient seawater *** work provides an opportunity to construct efficient and inexpensive electrocatalysts for hydrogen production.

关键词： Cobalt phosphide NiFe layered double hydroxide Interfacial engineering Oxygen evolution reaction Seawater oxidation

Two-stage aging treatment to accelerate aging kinetics without impairing strength in B_4C/7A04Al composite

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第8期67卷 2485-2492页

作者： CHEN YunTao ma GuoNan ZHU ShiZe WANG Dong xiao BoLv ma ZongYi Shi-Changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Centre of Excellence for Advanced materials Dongguan 523808China

Aging treatments are the key process to obtain satisfactory strength for 7xxxAl alloys and their composites. However, traditional single-stage(SS) aging is time-consuming to reach a peak strength condition. In this study, an efficient 120℃ + 160℃ two-stage(TS) aging treatment was proposed on a B_4C/7A04Al composite fabricated via powder metallurgy(PM) technology, which could acquire similar peak-aging strength but only took about 15% of the time compared to traditional 120℃ SS aging. The evolution of precipitation during the TS aging was investigated, as well as those of the 7A04Al alloys for comparison. In the second stage aging process, the higher aging temperature accelerated the nucleation of η′ phases inside the grains and thus increased the density of precipitates. Moreover, the short aging time limited the coarsening of precipitates and the broadening of precipitatefree zones. The above factors were beneficial for quickly obtaining satisfactory precipitation strengthening effects. The B_4C/7A04Al composite exhibited slower aging kinetics than the 7A04Al alloy in the TS aging. Mg elements consumption by the chemical reaction between B impurities introduced by B_4C particles and the Al matrix was considered to potentially retard the aging kinetics of the B_4C/7A04Al composite. Nevertheless, the precipitation sequence was not affected.

关键词： aluminum matrix composites aging treatment powder metallurgy mechanical properties precipitation

Echo State Network Based on Improved Knowledge Distillation for Edge Intelligence

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2024年第1期33卷 101-111页

作者： jian ZHOU Yuwen jianG Lijie XU Lu ZHAO Fu xiao College of Computer Nanjing University of Posts and Telecommunications jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks

Echo state network(ESN) as a novel artificial neural network has drawn much attention from time series prediction in edge intelligence. ESN is slightly insufficient in long-term memory, thereby impacting the prediction performance. It suffers from a higher computational overhead when deploying on edge devices. We firstly introduce the knowledge distillation into the reservoir structure optimization, and then propose the echo state network based on improved knowledge distillation(ESN-IKD) for edge intelligence to improve the prediction performance and reduce the computational overhead. The model of ESN-IKD is constructed with the classic ESN as a student network, the long and short-term memory network as a teacher network, and the ESN with double loop reservoir structure as an assistant network. The student network learns the long-term memory capability of the teacher network with the help of the assistant network. The training algorithm of ESN-IKD is proposed to correct the learning direction through the assistant network and eliminate the redundant knowledge through the iterative pruning. It can solve the problems of error learning and redundant learning in the traditional knowledge distillation process. Extensive experimental simulation shows that ESN-IKD has a good time series prediction performance in both long-term and short-term memory, and achieves a lower computational overhead.

关键词： Knowledge engineering Training Performance evaluation Computational modeling Time series analysis Artificial neural networks Reservoirs

同方期刊数据库

Control of fine particulate nitrate during severe winter haze in“2+26”cities

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第2期136卷 261-269页

作者： Chuang Qin xiao Fu Tao Wang jian Gao Jiaqi Wang Institute of Environment and Ecology Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Department of Civil and Environmental Engineering Hong Kong Polytechnic UniversityHong Kong 99907China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 10084China

The“2+26”cities,suffering the most severe winter haze pollution,have been the key region for air quality improvement in *** prominent nitrate pollution is one of the most challenging environmental issues in this region,necessitating development of an effective control ***,we use observations,and state-of-the-art model simulations with scenario analysis and process analysis to quantify the effectiveness of the future SO_(2)-NO_(X)-VOC-NH_(3) emission control on nitrate pollution mitigation in“2+26”*** on a serious winter haze episode,we find that limited NO_(X)emission reduction alone in the short-term period is a less effective choice than VOC or NH_3emission reduction alone to decrease nitrate concentrations,due to the accelerated NO_(X)-HNO_(3)conversion by atmospheric oxidants and the enhanced HNO_(3)to NO_(3)^(-)partition by ammonia,although deep NO_(X)emission reduction is essential in the long-term *** synergistic NH_(3) and VOC emission control is strongly recommended,which can counteract the adverse effects of nonlinear photochemistry and aerosol chemical feedback to decrease nitrate *** extra benefits will be reduced if the synergistic NH_(3) and VOC reduction is delayed,and thus reducing emission of multiple precursors is urgently required for the effective control of increasingly severe winter nitrate pollution in“2+26”cities.

关键词： Nitrate Winter haze pollution Emission reduction “2+26”cities

A Possible X-ray Quasi-periodic Oscillation in the Narrow-line Seyfert 1 Galaxy Mrk 142

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第6期24卷 191-200页

作者： xiao-Gu Zhong jian-Cheng Wang Yong-Yun Chen xiao-Ling Yu College of Physics and Electronic Engineering Qujing Normal UniversityQujing 655011China Yunnan Observatories Chinese Academy of SciencesKunming 650216China

A possible quasi-periodic oscillation(QPO) at frequency 7.045 × 10^(-5) Hz is found in the narrow-line Seyfert 1galaxy Mrk 142 in the data of XMM-Newton collected on 2020 April *** find that the QPO signal is statistically significantly larger than the 5σ level and highly coherent with quality factor Q > 5 at the 0.3–10 keV band by using the method of the Lomb–Scargle Periodogram,the Weighted Wavelet Z-transform and the *** analyze the data in 0.3–0.6 keV,0.6–1 keV,1–3 keV and 3–10 keV energy bands,and find obvious QPO signals at 0.3–0.6 keV and 1–3 keV *** then analyze the time-average spectra and time variability at the QPO frequency of 7.045 × 10^(-5) Hz,and use a model to fit *** find that the QPO signal mainly comes from the X-ray hot corona.

关键词： X-rays:galaxies galaxies:Seyfert accretion accretion disks radiation mechanisms:general

Surface-phonon-polariton-enhanced photoinduced dipole force for nanoscale infrared imaging

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第5期11卷 227-235页

作者： jian Li Junghoon Jahng Xuezhi ma Jing Liang Xue Zhang Qianhao Min xiao-Liang Wang Shuangjun Chen Eun Seong Lee Xing-Hua Xia State Key Lab of Analytical Chemistry for Life Science School of Chemistry and Chemical Engineering Nanjing University Hyperspectral Nano-Imaging Team Korea Research Institute of Standards and Science Institute of materials Research and Engineering Agency for ScienceTechnology and Research College of materials Science and Engineering Nanjing Tech University

The photoinduced dipole force(Pi DF) is an attractive force arising from the Coulombic interaction between the light-induced dipoles on the illuminated tip and the sample. It shows extreme sample-tip distance and refractive index dependence, which is promising for nanoscale infrared(IR) imaging of ultrathin samples. However, the existence of Pi DF in the mid-IR region has not been experimentally demonstrated due to the coexistence of photoinduced thermal force(Pi TF), typically one to two orders of magnitude higher than Pi DF. In this study, we demonstrate that, with the assistance of surface phonon polaritons, the Pi DF of c-quartz can be enhanced to surpass its Pi TF, enabling a clear observation of Pi DF spectra reflecting the properties of the real part of permittivity. Leveraging the detection of the Pi DF of phonon polaritonic substrate, we propose a strategy to enhance the sensitivity and contrast of photoinduced force responses in transmission images, facilitating the precise differentiation of the heterogeneous distribution of ultrathin samples.

关键词： surface phonon polariton photoinduced dipole force nanoscale infrared imaging ultrathin sample

Quantitatively Evaluating the Erosion and Preservation of Supergene Oxide Zones:Evidence from the Yulong Porphyry Cu Deposit,Eastern Tibetan Plateau

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Earth Science 2024年第1期35卷 280-282页

作者： xiao-Dong Deng jian-Wei Li State Key Laboratory of Geological Processes and Mineral Resources and School of Earth ResourcesChina University of GeosciencesWuhan 430074China

*** and erosion of sulfide ore deposits are important for understanding the post-mineralization processes that have significant effects on the preservation of primary orebodies(Velasco et al.,2013;Braxton et al.,2009;Brimhall et al.,1985).Supergene oxide zones are often developed in sulfide ore deposits,and are mainly composed of iron oxides and hydroxides zones in weathering profile(Andrew,1984;Thornber et al.,1981).

关键词： Eastern Tibetan weathering

MicroED as a powerful technique for the structure determination of complex porous materials

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2024年第3期43卷 41-54页

作者： Chao ma Cong Lin jian Li State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringNanjing UniversityNanjing210023China Department of Applied Biology and Chemical Technology The Hong Kong Polytechnic UniversityKowloonHong Kong China

Porous materials have garnered significant attention in recent *** the intrinsic relationship between their structures and properties requires precise knowledge of their atomic ***-crystal X-ray diffraction(SCXRD)has traditionally been the primary method for elucidating such structures,but it demands large,high-quality crystals,often exceeding 5μm in *** growth of these crystals can be a time-consuming process,especially for one-and two-dimensional *** explore structures at the nanoscale,MicroED(microcrystal electron diffraction(ED))offers unprecedented insights into the realm of *** revolutionary technique enables researchers to uncover intricate details within nanoscale structures,promising to reshape our fundamental understanding of *** this review,we delve into the applications of MicroED in the study of various porous materials,including zeolites,metal-organic frameworks(MOFs),and covalent organic frameworks(COFs).We emphasize the pivotal role of MicroED in nanomaterial characterization,enabling precise crystallographic analysis and phase identification.

关键词： Atomic structure MicroED Porous materials Three-dimensional electron diffraction