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Acta Metallurgica Sinica(English Letters) 2018年第3期31卷 290-298页

作者： Ke Yang Xin-Hui Fan Bing Li Yan-Hong Li Xin wang xuan-xuan Xu School of Material and Chemical Engineering Xi'an Technological University

The crystallization kinetics of Cu43Zr48Al9 and（Cu43Zr48Al9）98Y2 bulk metallic glasses in non-isothermal and isothermal conditions was studied by differential scanning *** the non-isothermal and isothermal modes,the average activation energy of（Cu43Zra8Al9）98Y2 is larger than that of Cu43Zr48Al9,meaning the higher stability against crystallization of（Cu43Zr48Al9）*** addition,the average activation energies for Cu43Zr48Al9 and（Cu43Zr48Al9）98Y2 calculated using Arrhenius equation in isothermal mode are larger than the values calculated by Kissinger-Akahira-Sunose method in non-isothermal mode,indicating that the energy barrier is higher in isothermal *** Johnson-Mehl-Avrami model was used to analyze the crystallization kinetics in the non-isothermal and isothermal *** Avrami exponent n for Cu43Zr48Al9 is above 2.5,indicating that the crystallization is mainly determined by a diffusion-controlled three-dimensional growth with an increasing nucleation rate,while the Avrami exponent n for（Cu43Zr48Al9）98Y2 is in the range of 1.5-2.5 in the non-isothermal mode,implying that the crystallization is mainly governed by diffusion-controlled three-dimensional growth with decreasing nucleation ***,the Avrami exponents n for Cu43Zr48Al9 and（Cu43Zr48Al9）98Y2 are different in the non-isothermal and isothermal conditions,which imply different nucleation and growth behaviors during the crystallization processes.

关键词： Bulk metallic glass Yttrium addition Crystallization behavior Activation energy

Discrete element modeling of sand behavior in a biaxial shear test

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第9期9卷 1176-1183页

作者： Zhi-yi HUANG Zhong-xuan YANG Zhen-yu wang Department of Civil Engineering Zhejiang University Hangzhou 310027 China MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310027 China Department of Civil Engineering The University of Hong Kong Hong Kong China

The mechanical behavior of sand is very complex, and depends on factors including confining pressure, density, and drainage condition. A soil mass can be contractive or dilative when subjected to shear loading, and eventually reaches an ultimate state, referred to as the critical state in soil mechanics. Conventional approach to explore the mechanical behavior of sand mainly relies on the experimental tests in laboratory. This paper gives an alternative view to this subject using discrete element method (DEM), which has attracted much attention in recent years. The implementation of the DEM is carried out by a series of numerical tests on granular assemblies with varying initial densities and confining pressures, under different test configurations. The results demonstrate that such numerical simulations can produce correct responses of the sand behavior in general, including the critical state response, as compared to experimental observations. In addition, the DEM can further provide details of the microstructure evolutions during shearing processes, and the resulting induced anisotropy can be fully captured and quantified in the particle scale.

关键词： Granular soil behavior Critical state Microstructure Discrete element method (DEM)

Research on new type of fast-opening mechanism in steam turbine regulating system and optimization of operation tactic

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第5期9卷 633-639页

作者： Xiao-xiao LI xuan-yin wang Fu-shang LI The State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China Shandong Electrical Power Institute Jinan 250002 China

With the analysis on regulating system in 200 MW steam turbine, the necessity of appending the fast-opening function to the original system is set forth and a new type of fast-opening mechanism is devised. The mathematical model of system is built up. With the use of AMESIM software, the displacement curve of the piston, the force curve of the cartridge valve spool, the pressure curve and the flux curve in the regulation process are obtained based on simulation. The performances of three fast-opening systems composed of cartridge valves with different diameters are compared. Based on the analysis on factors that affect the execution time of fast-opening, the dead zone of the fast-opening system is put forward. To overcome the defect, dif- ferent operation modes are adopted for different zones. The result shows that with the increase of the valve diameter, the regulating time in the dead zone significantly exceeds the fast-opening time in the whole journey. Accordingly, the optimization operation tactic in the dead zone and the qualification conditions are brought forward. The fast-opening system composed of 32 mm cartridge valves is taken as an example with use of the tactic. The simulation result shows that the maximum regulating time is shortened by 509 ms.

关键词： Steam turbine Fast-opening Regulating system AMESIM

Stabilization of Cu/ZnO Based Catalysts by Nickel Additive in Methanol Decomposition

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Chemical Research in Chinese Universities 2001年第4期17卷 420-425页

作者： XI Jing-yu wang Zhi-fei LU Gong-xuan State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical PhysicsThe Chinese Academy of SciencesLanzhou 730000P.R.China

A series of Cu/Zn based catalysts with and without Ni, prepared by the co-precipitation method, has been studied for methanol decomposition. CO and H2 are the major products. The Cu/Zn catalysts show a low initial activity and a poor stability. The formation of the CuZn alloys was observed in the deactivated Cu/Zn catalysts which were used for methanol decomposition at 250 . When small amounts of Ni were added in the catalyst, the Cu/Zn/Ni(molar ratio 5/4/ x) catalysts showed a high activity at a low temperature. The activity and the stability of the catalyst depend on the nickel content. The activity of the Cu/Zn/Ni catalysts was maintained at a. relatively stable value of 78% conversion of methanol with 95% selectivity of H2, 93% selectivity of CO, and a more than 70% yield of hydrogen was obtained at 250 C when x >1. The stability of the Cu/Zn/Ni (molar ratio 5/4/x) catalysts showed the maximum (ca 88%) when x=1. The stabilization effect of nickel on the Cu/Zn based catalysts may lead to the increasing of the dispersion of active Cu species and the prevention of CuZn alloys formation.

关键词： Nickel Cu/Zn catalysts Stabilization Methanol Decomposition

Enhancing the thermal conductivity of nanofibrillated cellulose films with 1D BN belts formed by in-situ generation and sintering of BN nanosheets

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Journal of Advanced Ceramics 2023年第12期12卷 2257-2270页

作者： Baokai wang Zheng Zhao Mengyi Li Mengyang Niu Jialu Tian Chang Yu Shiqin Wan ming Yue Weiwei xuan Wenbin Cao Zhaobo Tian Kexin Chen Qi wang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China School of Microelectronics Southern University of Science and TechnologyShenzhen 518055China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

The rapid miniaturization and high integration of modern electronic devices have brought an increasing demand for polymer-based thermal management materials with higher thermal *** nitride nanosheets(BNNs)have been widely used as thermally conductive fillers benefiting from the extremely high intrinsic thermal ***,the small lateral size and weak interface bonding of BNNs enabled them to only form thermally conductive networks through physical overlap,resulting in high interfacial thermal *** address this issue,an innovative strategy based on interface engineering was proposed in this ***-aspect-ratio boron nitride belts(BNbs)were successfully synthesized by carbon thermal reduction nitridation method through the in-situ generation and sintering of *** surface of BNb showed the sintering of numerous smaller-sized BNNs,which precisely addresses the issue of weak interfacial bonding between *** this basis,the as-synthesized BNbs were combined with nano-fibrillated cellulose(NFC)to prepare NFC/BNb composite films through a facile vacuum filtration *** to the thermally conductive network formed by the horizontal oriented arrangement of BNb and their particular morphological advantages,the NFC/BNb films demonstrated significantly higher in-plane thermal conductivity than that of NFC/BNNs films,achieving the highest value of 19.119 W·m^(−1)·K^(−1) at a 20 wt%filling *** addition,the NFC/BNb films also exhibited superior thermal stability,mechanical strength,flexibility,and electrical insulation performance,suggesting the significant application potential of the designed BNb fillers in the thermal management field.

关键词： boron nitride(BN) thermal management materials vacuum filtration flexible thermally conductive films

Enhancing the Crystallization Performance of Poly(L-lactide) by Intramolecular Hybridizing with Tunable Self-assembly-type Oxalamide Segments

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Chinese Journal of Polymer Science 2021年第1期39卷 122-132,I0008页

作者： Man-Man Yu Wei-Jun Yang De-Yu Niu Xiao-Xia Cai Yun-xuan Weng Wei-Fu Dong ming-Qing Chen Peng-Wu Xu Yang wang Hong Chu Pi-ming Ma The Key Laboratory of Synthetic and Biological Colloids Ministry of EducationSchool of Chemical and Material EngineeringJiangnan UniversityWuxi 214122China Beijing Key Laboratory of Quality Evaluation Technology for Hygiene and Safety of Plastics Beijing Technology and Business UniversityBeijing 100048China

In this work, hydroxyl-terminated oxalamide compounds N^(1),N^(2)-bis(2-hydroxyethyl)oxalamide(OXA1) and N^(1),N^(1)′-(ethane-1,2-diyl)bis(N^(2)-(2-hydroxyethyl)oxalamide(OXA2) were synthesized to initiate the ring-opening polymerization of L-lactide for preparation of oxalamide-hybridized poly(L-lactide)(PLA_(OXA)), i.e., PLA_(OXA1) and PLA_(OXA2). The crystallization properties of PLA were improved by the self-assembly of the oxalamide segments in PLA_(OXA) which served as the initial heterogeneous nuclei. The crystal growth kinetics was studied by HoffmanLauritzen theory and it revealed that the nucleation energy barrier of PLA_(OXA1) and PLA_(OXA2) was lower than that of PLA. Consequently, PLA_(OXA) could crystallize much faster than PLA, accompanied with a decrease in spherulite size and half-life crystallization time by 74.8% and 86.5%(T=125 ℃), respectively. In addition, the final crystallinity of PLA_(OXA1) and PLA_(OXA2) was 6 and 8 times higher, respectively, in comparison with that of neat PLA under a controlled cooling rate of 10 ℃/min. The results demonstrate that the hybridization of oxalamide segments in PLA backbone will serve as the self-heteronucleation for promoting the crystallization rate. The higher the content of oxalamide segments(PLA_(OXA2) compared with PLA_(OXA1)) is, the stronger the promotion effect will be. Therefore, this study may provide a universal approach by hybridizing macromolecular structure to facilitate the crystallization of semi-crystalline polymer materials.

关键词： Poly(L-lactide) Oxalamide compounds Self-heteronucleation Crystallization kinetics

Passive particles driven by self-propelled particle:The wake effect

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Chinese Physics B 2024年第4期33卷 500-507页

作者：郑凯选汪静文王世锋聂德明 Institute of Fluid Mechanics China Jiliang UniversityHangzhou 310018China Department of Mechanical Engineering Hangzhou Vocational&Technical CollegeHangzhou 310018China

This work focuses on numerically studying hydrodynamic interaction between a passive particle and a self-propelled particle,termed a squirmer,by using a two-dimensional lattice Boltzmann method(LBM).It is found that the squirmer can capture a passive particle and propel it simultaneously,provided the passive particle is situated within the squirmer's *** research shows that the critical capture distance,which determines whether the particle is captured,primarily depends on the intensity of the squirmer's *** stronger dipolarity of squirmer results in an increased critical capture ***,the Reynolds number is found to have minimal influence on this ***,the passive particle,when driven by the squirmer's wake,contributes to a reduction in the squirmer's *** results in a mutual acceleration for both *** findings can provide valuable perspectives for formulating the principles of reducing the drag of micro-swimmers and help to achieve the goal of using micro-swimmers to transport goods without physical tethers.

关键词： lattice Boltzmann method(LBM) self-propelled particles particle-laden flow

Climatology of Wind-Seas and Swells in the China Seas from Wave Hindcast

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Journal of Ocean University of China 2020年第1期19卷 90-100页

作者： QIAN Chengcheng JIANG Haoyu wang xuan CHEN Ge North China Sea Marine Forecasting Center of State Oceanic Administration Qingdao 266100China Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and TechnologyQingdao 266000China College of Information Science and Engineering Ocean University of ChinaQingdao 266100China College of Marine Science and Technology China University of GeosciencesWuhan 430000China College of Ocean Science and Engineering Shanghai Maritime UniversityShanghai 200000China

The wind-sea and swell climates in the China Seas are investigated by using the 27-yr Integrated Ocean Waves for Geophysical and other Applications(IOWAGA)hindcast data.A comparison is made between the significant wave height from the IOWAGA hindcasts and that from a jointly calibrated altimetry dataset,showing the good performance of the IOWAGA hindcasts in the China Seas.A simple but practical method of diagnosing whether the sea state is wind-sea-dominant or swell-dominant is proposed based on spectral *** from the characteristics of wind-seas and swells in the open ocean,the wave fields in the enclosed seas such as the China Seas are predominated by wind-sea events in respect of both frequencies of occurrences and energy weights,due to the island sheltering and limited *** energy weights of wind-seas in a given location is usually more significant than the occurrence probability of wind-sea-dominated events,as the wave energy is higher in the wind-sea events than in the swell events on average and extreme wave heights are mostly related to *** most energetic swells in the China Seas(and other enclosed seas)are‘local swells’,having just propagated out of their generation ***,the swells coming from the West Pacific also play an important role in the wave climate of the China Seas,which can only be revealed by partitioning different swell systems in the wave spectra as the energy of them is significantly less than the‘local swells’.

关键词： the China Seas wind-sea swell wave climate WAVEWATCH Ⅲ

Understanding the Activity Performance of Comets 38P/Stephan-Oterma,64P/Swift-Gehrels and C/2017 M4(ATLAS)through Broadband Photometric Observations

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Research in Astronomy and Astrophysics 2024年第8期24卷 147-156页

作者： xuan Zhang Jin-Zhong Liu Le-Tian wang Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China

In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and *** extracted morphological features through image enhancement techniques and calculated the dust activity parameter,Afρ,along with dust mass loss rates and coma color indices using broadband photometric *** morphological analysis uncovered a spectrum of dust characteristics among the observed comets,ranging from a significant twisted structure in comet 38P/Stephan-Oterma’s coma to the regular coma envelope surrounding comet 64P/*** Afρvalues varied between 148.8±0.3 cm for 64P/Swift-Gehrels and1118.5±6.2 cm for C/2017 M4(ATLAS)(measured within a reference aperture radius ofρ=6″),indicating a range from moderate to high activity *** mass loss rates were estimated from 328.1 kg s^(-1)for comet 64P/Swift-Gehrels to 1395.5 kg s^(-1)for comet C/2017 M4(ATLAS).The color indices of comets 38P/Stephan-Oterma and C/2017 M4(ATLAS)closely resemble the average colors of active short-period comets and active longperiod comets,*** contrast,64P/Swift-Gehrels exhibits a significantly bluer hue than typical Jupiter family comets.

关键词： comets general-comets individual(38P/Stephan-Oterma,64P/Swift-Gehrels,C/2017 M4(ATLAS))-techniques photometric

The Early Permian Woniusi Flood Basalts from the Baoshan Terrane, SW China: Petrogenesis and Geodynamic Implications

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Acta Geologica Sinica(English Edition) 2020年第6期94卷 2091-2114页

作者： CAO Jun ZHANG Gaizhi wang xuan CHEN Jun State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China Shandong Key Laboratory of Depositional Mineralization&Sedimentary Minerals Shandong University of Science and TechnologyQingdaoShandong 266590China School of Earth Sciences East China University of TechnologyNanchang 330013China State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China

The Woniusi flood basalts from the Baoshan terrane,SW China,represent a significant eruption of volcanic rocks which were linked to the Late Paleozoic rifting of the Cimmeria from the northern margin of East ***,the precise mechanism for the formation and propagation of the rifting is still in *** we report 40 Ar/39 Ar dating,whole-rock geochemistry,and Sr-Nd-Pb isotopes for the Woniusi basalts from the Baoshan terrane of SW China,with the aim of assessing if a mantle plume was related to the formation of the continent Cimmeria.40 Ar/39 Ar dating of the Woniusi basalts yielded ages of 279.3±1.1 Ma and 273.9±1.5 Ma,indicating they were emplaced during the Early ***-rock geochemistry shows that these basalts have subalkaline tholeiitic affinity,low Ti O2(1.2-2.2 wt%),and fractionated chondrite-normalized LREE and nearly flat HREE patterns[(La/Yb)N=2.86-5.77;(Dy/Yb)N=1.21-1.49]with noticeable negative Nb and Ta anomalies on the primitive mantle-normalized trace element ***ε(Nd)(t)values(-4.76 to+0.92)and high(206 Pb/204 Pb)i(18.40-18.66)along with partial melt modeling indicates that the basalts were likely derived from a sub-continental lithospheric mantle(SCLM)source metasomatized by subduction-related *** the basis of a similar emplacement age to the Panjal basalts and Qiangtang mafic dykes and flood basalts in the Himalayas,combined with a tectonic reconstruction of Gondwana in the Early Permian,we propose that the large-scale eruption of these basalts and dykes was related to an Early Permian mantle plume that possibly initiated the rifting on the northern margin of East Gondwana.

关键词： geochemistry flood basalts Early Permian Baoshan Gondwana