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China Foundry 2024年第4期21卷 379-386页

作者： yang Liao Ye-yuan Hu Kosuke Ikeda Ryoji Okabe Rui-fen Wu Ryota Ozaki qing-yan Xu Key Laboratory for Advanced Materials Processing Technology School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Composite Laboratory Research&Innovation Center Mitsubishi Heavy Industries Ltd.Nagasaki 8510392Japan

Polypropylene is commonly used as a binder for ceramic injection molding,and rapid cooling is often encountered during ***,the crystallization behavior of polypropylene shows a strong dependence on cooling rate due to its semi-crystalline ***,the influence of cooling rate on the quality of final product cannot be *** this study,the fast differential scanning calorimetry(FSC)test was performed to study the influence of cooling rate on the non-isothermal crystallization behavior and non-isothermal crystallization kinetics of a copolymer polypropylene(PP BC03B).The results show that the crystallization temperatures and crystallinity decrease as the cooling rate *** addition,two exothermic peaks occur when cooling rate ranges from 30 to 300 K·s^(-1),indicating the formation of another crystal ***,Ozawa and Mo equations were used to explore the non-isothermal crystallization kinetics,and it can be concluded that the Mo method is suitable for this study.

关键词： cooling rate crystallization temperature crystallinity non-isothermal crystallization kinetics FSC copolymer polypropylene

Exploring a new path of green and efficient utilization of sinter return fine to produce composite pellets

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Journal of Iron and Steel Research International 2024年第7期31卷 1610-1622页

作者： yan-biao Chen Wen-guo Liu Hao Guo Jing-song Wang qing-guo Xue Hai-bin Zuo State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China MCC Capital Engineering and Research Incorporation Limited Beijing 100176China

Efficient utilization of sinter return fine is an important measure to reduce cost,increase efficiency,save energy and reduce emission.A new path of green and efficient utilization of return fine was proposed to produce composite *** metallurgical properties of composite pellets under the condition of hydrogen-rich blast furnace were *** experimental results indicate that the coated concentrate was consolidated for the composite pellets through normal Fe_(2)O_(3) *** the surface of core return fine,the liquid phase formed due to its low-melting point,assimilated the adjacent concentrate,and then consolidated with the temperature *** with regular pellets,the com-pressive strength and reduction swelling index of composite pellets were decreased,but the reducibility index and softening-melting properties were *** addition,the reduction degradation index of composite pellets was sig-nificantly higher than that of ***,adding composite pellets was conducive to indirect reduction in blast furnace,reducing fuel ratio and improving production *** to the effect of the roasting system on the metallurgical properties,the roasting temperature and time were determined as 1250℃and 30 min,*** composite pellets can be produced under the traditional pelletizing process.

关键词： Sinter Return fine Composite pellet Roasting system Metallurgical property Hydrogen-rich blast furnace

Current status of Mycoplasma pneumoniae infection in China

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World Journal of Pediatrics 2024年第1期20卷 1-4页

作者： Chao yan Guan-Hua Xue Han-qing Zhao yan-Ling Feng Jing-Hua Cui Jing Yuan Department of Bacteriology Capital Institute of PediatricsNo.2Yabao RoadBeijing 100020People's Republicof China

Mycoplasma pneumoniae(***)is one of the most important pathogens for community-acquired pneumonia worldwide,especially in children and adolescents[1,2].*** is easily transmitted through droplets or direct contact in densely populated,enclosed,or poorly ventilated *** incubation period is 1-3 weeks,and it is contagious from the incubation period to a few weeks after clinical symptom *** infection can occur in any season,and there are differences in the epidemic seasons among regions in China[3].The most suitable culture temperature for *** is between 35℃C and 37 C,and therefore,hot weather may make it survive longer in the environment and spread *** is more common in autumn and winter in northern China,while it is more prevalent in summer and autumn in southern China.

关键词： winter weather autumn

Configuring single-layer MXene nanosheet onto natural wood fiber via C-Ti-C covalent bonds for high-stability Li-S batteries

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Journal of Energy Chemistry 2024年第8期95卷 701-711,I0016页

作者： yangyang Chen Yu Liao Ying Wu Lei Li Zhen Zhang Sha Luo Yiqiang Wu yan qing College of Materials Science and Technology Central South University of Forestry and TechnologyChangsha 410004HunanChina

Lithium-sulfur batteries(LSBs)are considered promising candidates for next-generation battery technologies owing to their outstanding theoretical energy density and ***,the low conductivity and polysulfide shuttling effect of S cathodes severely hamper the practical performance of ***,in situ-generated single layer MXene nanosheet/hierarchical porous carbonized wood fiber(MX/PCWF)composites are prepared via a nonhazardous eutectic activation strategy coupled with pyrolysis-induced gas *** unique architecture,wherein single layer MXene nanosheets are constructed on carbonized wood fiber walls,ensures rapid polysulfide conversion and continuous electron transfer for redox *** C-Ti-C bonds formed between MXene and PCWF can considerably expedite the conversion of polysulfides,effectively suppressing the shuttle *** impressive capacity of 1301.1 m A h g^(-1)at 0.5 C accompanied by remarkable stability is attained with the MX/PCWF host,as evidenced by the capacity maintenance of 722.6 m A h g^(-1)after 500 ***,the MX/PCWF/S cathode can still deliver a high capacity of 886.8 m A h g^(-1)at a high S loading of 5.6 mg cm^(-2).The construction of two-dimensional MXenes on natural wood fiber walls offers a competitive edge over S-based cathode materials and demonstrates a novel strategy for developing high-performance batteries.

关键词： Lithium-sulfur batteries S cathodes MXene nanosheets Wood fiber C-Ti-C bonds

Spatial construction of ultrasmall Pt-decorated 3D spinel oxidemodified N-doped graphene nanoarchitectures as high-efficiency methanol oxidation electrocatalysts

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Rare Metals 2024年第1期43卷 186-197页

作者： Qi Zhang Min-Min yan Wen-Fa Du Chen-Yu Yin Jian Zhang Lu yang Yun-qing Kang Hai-yan He Hua-Jie Huang College of Mechanics and Materials Hohai UniversityNanjing 210098China New Energy Technology Engineering Lab of Jiangsu Province College of ScienceNanjing University of Posts&Telecommunications(NUPT)Nanjing 210023China International Center for Materials Nanoarchitectonics(WPIMANA) National Institute for Materials ScienceTsukuba 305-0044IbarakiJapan

Direct methanol fuel cell technology recently becomes the focus of both academic and engineering circles,which stimulates the exploitation and utilization of advanced electrode catalysts with high activity and long ***,we demonstrate a robust bottom-up approach to the spatial construction of three-dimensional(3D) spinel manganese-cobalt oxide-modified N-doped graphene nanoarchitectures decorated with ultrasmall Pt nanoparticles(Pt/MnCo_(2)O_(4)-NG) via a controllable selfassembly *** incorporation of MnCo_(2)O_(4)nanocrystals provides abundant hydroxyl sources to promote the oxidative removal of CO-like byproducts on Pt sites,while the existence of 3D porous N-doped graphene networks facilitates the transportation of both ions and electrons in the hybrid system,thus giving rise to remarkable synergetic coupling effects during the methanol oxidation ***,the optimized Pt/MnCo_(2)O_(4)-NG nano architecture expres ses exceptional electrocatalytic properties with a large electrochemically active surface area of 99.5 m^(2)·g^(-1),a high mass activity of1508.3 mA·mg^(-1),strong toxicity resistance and reliable long-term durability,which have obvious competitive advantages over those of conventional Pt/carbon black,Pt/carbon nano tube,Pt/graphene,and Pt/N-doped graphene catalysts with the same Pt usage.

关键词： Platinum MnCo_(2)O_(4) 3D graphene Electrocatalysts Methanol oxidation

Electronic control seed-metering system for precision seeding maize based on fuzzy PID

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International Journal of Agricultural and Biological Engineering 2024年第4期17卷 217-226页

作者： Xiaoshun Zhao Hongpeng Zhao Zehe Wang Jincai Li Huali Yu qing yan State Key Laboratory of North China Crop Improvement and Regulation Hebei Agricultural UniversityBaoding 071001HebeiChina College of Mechanical and Electrical Engineering Hebei Agricultural UniversityBaoding 071001HebeiChina

Aiming at the problem of poor uniformity of maize sowing caused by ground wheel slip,an electronic control seed-metering system(ECSMS)for maize single seed precision sowing was designed and a mathematical model for motor control of the ECSMS was *** PID parameters were set by Z-N method and fuzzy *** fuzzy PID control design and Simulink simulation were completed by MATLAB,which reduced response time of the system by 0.23 s and improved the control *** on the JPS-12 test bench show that the qualification index(QI)of maize seed-metering device with the ECSMS increases by 4.47%,the multiples index(MI)decreases by 1.96%,the miss index(MIX)decreases by 2.81%,and the coefficient of variation(CV)of qualified seed spacing decreases by 5.06%,and the sowing uniformity has been greatly *** results of the soil-tank test bench show that the system has good sowing uniformity and *** the QI is 96.74%,the MI is 2.15%,the MIX is 1.10%,and the CV of qualified seed spacing is 16.24%.Under different setting seed spacing and different sowing operation speed,the change range of seeding quality index was within 10%.The results of field sowing test show that the QI was 84.21%,the MI was 2.63%,the MIX was 7.89%,and the CV of qualified seed spacing was 22.15%,which meet the requirements of JB/T 10293-2013‘Specification for single seed planters(precision planters)’and the agronomic requirements for maize precision *** system runs stably and reliably in practical operation and has good operation performance.

关键词： maize seed-metering system electronic control precision sowing parameters tuning fuzzy PID control simulink simulation

Comprehensive evaluations of heat transfer performance with conjugate heat dissipation effect in high-speed rotating free-disk modeling of aero-engines

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Fundamental Research 2024年第3期4卷 611-623页

作者： Aqiang Lin Gaowen Liu Ran Chang yan Chen qing Feng School of Power and Energy Northwestern Polytechnical UniversityXi'an 710129China Shaanxi Key Laboratory of Thermal Science in Aero-engine System Northwestern Polytechnical UniversityXi'an 710072China Research&Development Institute of Northwester

Thermal boundary conditions of the turbine disk cavity system are of great importance in the design of secondary air systems in *** study aims to investigate the complex heat transfer mechanisms of a rotating turbine disk under high-speed conditions.A high-speed rotating free-disk model with Dorfman empirical solutions is developed to evaluate the heat transfer performance considering various ***,the influence of compressibility,variable properties,and heat dissipation is determined using theoretical and numerical *** particular,a novel combined solution method is proposed to simplify the complex heat transfer *** results indicate that the heat transfer performance of a free disk is primarily influenced by the rotating Mach number,rotating Reynolds number,Rossby number,and wall temperature *** heat transfer temperature and Nusselt number of the free disk are strongly correlated with the rotating Mach number and rotating Reynolds *** reveals that heat dissipation is a critical factor affecting the accurate evaluation of the heat transfer performance of the turbine ***,the combined solution method can serve as a reference for future investigations of flow and heat transfer in high-speed rotating turbine disk cavity systems in aero-engines.

关键词： Aero-engine Rotating turbine disk Dimensional analysis Compressibility Heat dissipation Dorfman empirical solution

Study on the local time asymmetry of the Earth's ring currents based on multiple low-Earth-orbit satellite magnetic observations

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Science China Technological Sciences 2024年第11期67卷 3354-3364页

作者： OU JiaMing JIANG Yi yan qing State Key Laboratory of Lunar and Planetary Sciences Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute Macau University of Science and Technology Macau Institute of Space Technology and Application

The azimuthal morphology of Earth's ring currents has consistently shown asymmetry during extreme space weather events at low latitudes, particularly during geomagnetic storms. A dawn-dusk pattern has been detected during the storm main phase through near-Earth and in-situ magnetic measurements. This asymmetry is believed to arise from asymmetric solar windmagnetosphere coupling and is linked to the closure of the ring current. Recent evidence has confirmed the existence of asymmetric ring currents during quiet times and the storm recovery phase. This phenomenon may be closely related to the evolution of ring currents, including plasma injection and decay processes. In this study, the local time asymmetry of the ring current is estimated using data from low-Earth-orbit Swarm and Macao Science Satellite-1(MSS-1) missions. Spherical harmonics models are developed to quantify the magnetic field of ring currents through external Gauss coefficients during both quiet periods and the storm recovery phase. Several features of dawn-dusk asymmetry are observed in various cases in different months.(1) The maximum difference in magnetic value across local time ranges from 3 to 10 nT, showing relative invariance compared with various Sym-H levels.(2) Stronger magnetic signals are detected at the premidnight sector during quiet times and at the afternoon sector during the storm recovery phase.(3) Magnetic perturbations remain at a lower level during the postmidnight and morning sectors. Although the pattern of local time asymmetry differs between quiet times and the recovery phase,dawn-dusk asymmetry remains the most pronounced feature, affecting the trapping and loss of charged particles in the inner magnetosphere. Combining Swarm and MSS-1 magnetic observations can enable convenient monitoring of the detailed azimuthal local time effects of the ring current at various disturbance levels in the future.

关键词： Earth’s ring currents local time asymmetry, SHA model Macao Science Satellite-1

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Silurian integrative stratigraphy,biotas,and paleogeographical evolution of the qinghai-Tibetan Plateau and its surrounding areas

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Science China Earth Sciences 2024年第4期67卷 1005-1035页

作者： Zhongyang CHEN qing CHEN Guangxu WANG Xiang FANG Peng TANG Guanzhou yan Wenwei YUAN Bing HUANG Xiaole ZHANG Kui yan Yuandong ZHANG Yi WANG State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of SciencesNanjing 210008China University of Chinese Academy of Sciences Beijing 100049China

The Silurian palaeontology and stratigraphy of the qinghai-Tibetan Plateau have been studied for more than100 *** the launch of the Second Tibetan Plateau Scientific Expedition and Research,it is necessary to update the summaries of the Silurian stratigraphy and fossil assemblages of the qinghai-Tibetan Plateau and their correlation with its surrounding *** this study,we have selected 33 sections from the qinghai-Tibetan Plateau and its surroundings areas,summarised the available data in terms of stratigraphic regionalisation,lithostratigraphy,chronostratigraphy,and biostratigraphy,and divided the study area into four stratigraphic provinces:the Xizang-Western Yunnan-Western Sichuan Province,the KunlunQilian Province,the South China Province,and the Tarim *** general,the Silurian strata in the qinghai-Tibetan Plateau is more complete than those in other areas of *** studies of the vertebrate faunas,sporomorph assemblages,and brachiopod faunas of the study area indicate a closer geographical relationship between the South China,Tarim,and Indochina palaeoplates,than previously *** with the surrounding areas where Silurian strata have been extensively studied,the study of Silurian strata in the main part of the qinghai-Tibetan Plateau is still in the preliminary *** the future,it is necessary to conduct research on the age,distribution,and resource potential of basal Silurian black shales to provide new directions for shale gas exploration and development in *** shallow marine strata of the middle to upper Silurian require further *** that the Silurian System in the qinghai-Tibetan Plateau is more complete,it has the potential to supplement and improve the study of the carbon isotope stratigraphy of the Silurian in China.

关键词： qinghai-Tibetan Plateau Silurian Stratigraphic regionalisation Lithostratigraphy Biostratigraphy Palaeogeographical evolution

Solitons and Their Biperiodic Pulsation in Ultrafast Fiber Lasers Based on CB/GO

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Chinese Physics Letters 2024年第8期41卷 28-32页

作者： Zhen-Tao Ju Zhi-Zeng Si Xin yan Chao-qing Dai College of Optical Mechanical and Electrical EngineeringZhejiang A&F UniversityLin’an 311300China

The carbon black(CB)is introduced to manufacture CB/graphene oxide(GO)composite material to mitigate limitations of GO as a saturable absorber with the excellent performance in ultrafast fiber *** a central wavelength of 1555.5 nm,the stable mode-locked pulse with width of 656 fs,repetition rate of 20.16 MHz,and high signal-to-noise ratio of 82.07 dB is experimentally ***,experimental observations for pulsation phenomena of vector biperiodic solitons combining period-1 and period-17,period-2 and period-32,period-3 and period-36 are verified via simulations.

关键词： fiber periodic absorber